WO2008028673A1

WO2008028673A1 - Liquid-cooled eddy current brake

Info

Publication number: WO2008028673A1
Application number: PCT/EP2007/007823
Authority: WO
Inventors: Andreas Seiwald
Original assignee: Andreas Seiwald
Priority date: 2006-09-08
Filing date: 2007-09-07
Publication date: 2008-03-13
Also published as: AT505585A3; AT505585A2

Abstract

Liquid-cooled eddy current brake for retarding a shaft and axis, respectively, of a vehicle or a drive of all kind by a claw pole rotor as a magnetic-field-transmitting and force-taking unit, driven by said shaft and axis, respectively, a unit formed as a stator and an induct ring formed as a stator, in which one of said three components comprises the inducing component of the eddy current brake, one of said three components comprises the induced component of the eddy current brake and one of said components comprises the force-transmitting component of the eddy current brake, in which the inducing components and the induced component of the eddy current brake are arranged statically and fixedly, respectively, and the force-transmitting components are arranged dynamically and rotatably, respectively. The present invention also discloses a liquid-cooled eddy current brake having a first and a second chamber comprising liquid, wherein the liquid level can be adjusted with respect to the operation status of the brake. The first chamber comprising the rotor, has a low liquid level in towed operation, however, the first chamber has a high liquid level in braking operation.

Description

LIQUID-COOLED EDDY CURRENT BRAKE

The present application claims the priority of the Austrian patent application A 1501/2006 filed on September 8^th, 2006.

The invention relates to a liquid-cooled eddy-current brake for braking a shaft and an axis, respectively of a vehicle or a drive system of any kind, having a claw-pole rotor (rotor), which is driven by a shaft and an axis, respectively, in one module and a stator in two modules. Wherein one of said three modules comprises the inducing component of the eddy-current brake, wherein one of said three modules performs the transmission of the magnetic field to the induced module and transmits the generated braking torque to a shaft and wherein one of said three modules comprises the induced component of the eddy-current brake.

A liquid-cooled eddy-current brake is already known from EP-B 1-331 559. In consideration of these techniques the rotor comprises the inducing component of the eddy-current brake with the energising coils. The stator comprises an induction ring made of a ferromagnetic material as an inducing component of the eddy-current brake. Conduits are provided at the outside of this induction ring, where cooling water is passed through cooling the induct ring.

An additional technical feature of said brake is that the required energizing current of the coils can only be switched on by a generator connected and downstream, respectively. These technical disadvantages are considerable, as the generator provides the required current only from a specific revolution speed (> 500 min^"1). Hence on the one hand, the effect desired for eddy- current brakes is that large braking torque at low revolution speed can not be achieved because of the generator that is required. Furthermore such brakes can only be manufactured with a large technical expense and have a bad effect on the installation length, additionally. Additionally the rotor can only be operated in dry mode, because the coils and the current feed cables are generally not suitable for the component rotating in a liquid bath. In order to provide a high magnetic effect, small spacings (e.g. air gaps and slits, respectively) are essential to electrodynamic machines and brakes between stator and rotor. In general small air gaps do not generate any problems during dry operation of the rotor, provided that the necessary mechanical stiffness of the components is given. Even at high revolution speed, narrow air gaps do not have an appreciable effect on the tow drag of rotating components.

The tow drag acts fundamentally contrarian, if the rotating components operate in an liquid bath, e.g. an oil bath. The narrower the gap and the higher the revolution speed, the higher is the tow drag and the power loss resulting therefrom. Moreover the immersion depth of the rotating components into the liquid bath determines the power loss decisively. The higher immersion depth is, the higher is the power loss. There is also an effect to the power loss from the viscosity of the lubricant, but this is not part of the present invention.

Due to essential parameters, e.g. extreme small-sized spacings between the induct rung and the claw poles, the present invention provides an effective means, to decrease the power loss in towed operation to an acceptable level together with an effective cooling in braking operation.

It is essential to maintain a high immersion depth and a high liquid-level, respectively, in braking operation in order to provide an efficient cooling of the inner side of the induct ring. However, in towed operation it is essential to maintain a small immersion depth and a low liquid-level, respectively in order to reduce tow drags to a minimum.

In consequence a low liquid-level significantly reduces the power loss in towed operation, because the cooling of the induct ring at the inner side is not needed in this case.

It is an object of the invention to avoid the disadvantages of said known liquid-cooled eddy- current brake and to provide an eddy-current brake of said category, with essentially enhanced and simplified inducing components and induced components. In result, as few limitations as possible, or no limitations should be present with respect to setting up, employment and function. This object is solved by an eddy-current brake having the features of claim 1.

Hence the present invention provides a liquid-level adjustment- system for an eddy current brake, at least a first 43 and a second chamber 42 within the housing 1 of the eddy-current brake (retarder housing) and at least a first 50 and second channel 51 in order to provide a primary liquid closed loop. Within this primary liquid closed loop a liquid is transported from the second chamber 42 via the first channel 50 into the first chamber 43. Further the liquid is transported back from the first chamber 43 via the second channel 51 to the second chamber42, wherein said transportation back into the second chamber 42 is performed by e.g. the rotor itself. The rotor of the eddy current brake runs within the first chamber 43. Said liquid is adapted for cooling the inside of the first chamber 43 and is also adapted for lubrication of the mechanical parts inside of the first chamber, i.e. in a preferred embodiment said liquids can be oil or water.

Further the present invention provides at least one secondary liquid closed loop having at least one heat exchanger 56. The heat exchanger 56 collects heat from the primary liquid closed loop, e.g. when the liquid of the primary liquid closed loop runs through said heat exchanger 56, in order to cool the liquid of primary closed loop. Preferably the stator housing 1 itself acts as a heat exchanger 56. Said secondary liquid closed loop further comprises at least one secondary sensor device 37 comprising one or more sensors, e.g. a temperature sensor for measuring values within the secondary liquid closed loop. The induct ring 10 of the eddy current brake is adapted to form a divider between the primary and the secondary liquid loop so that the liquids in both liquid closed loops can not be mixed. Preferably the induct ring 10 of the eddy current brake is further adapted to comprise a heat exchanger 56 in order to absorb heat at its inner side, i.e. from the first chamber 50, and to transmit said heat to its outer side and into the secondary liquid loop.

With respect to said liquids, it is more preferable to use oil within the primary liquid closed loop and to use water within the secondary closed loop. The inside of the first chamber 43 at least comprises the rotor of the eddy current brake, but can also comprise e.g. further gearings or revolution-speed increasors 47. Further the present invention provides at least one primary sensor device 38 comprising one or more sensors, e.g. temperature sensor, for measuring values within the first chamber, at least one control device 34, e.g. a continuous-flow controller, comprising a valve 44 for controlling the flow through the first channel 50 in response to received information from the primary sensor device 38. The sensor device can also be adapted for measuring pressure, liquid level, viscosity, syncrisis of the liquid, volume of the liquid, flow speed of the liquid or a combination thereof. Said valve is located in the said first channel 50, wherein said first channel 50 is adapted to provide a liquid flow from said second chamber 42 to said first chamber 43. Further a second channel 51 is provided to connect the first chamber 43 with the second chamber 42 in order to form a primary liquid closed loop. Hence the liquid is able to flow and to be transported, respectively from the second chamber 42 via the first channel 50 into the second chamber 43, and the liquid is then able to flow and to be transported, respectively from the first chamber 43 to the back to the second chamber 42 via the second channel 51.

According to the present invention the first chamber 43 provides a liquid-bath wherein the rotor of the eddy current brake runs. Preferably the rotor is formed as a claw pole rotor and the second chamber 42 is formed as a liquid-collecting chamber. The first channel 50 connects the second chamber 42 to the first chamber 43 in order to allow a liquid to flow from the second chamber 42 to the first chamber 43. The second channel 51 connects the first chamber 43 to the second chamber 42, in order to allow a liquid to flow from the first chamber 43 to the second chamber 42. This system is forming a primary liquid closed loop. The number of chambers and channels is not restricted and has to be adapted corresponding to the respective applications. It is also an option to form a system according to the invention that provides multiple eddy-current brakes and/or multiple chambers and channels, respectively, both serial and parallel.

Additional advantageous embodiments of the invention are defined by the dependent claims and are illustrated in the following with the figures 1 to 12: Fig. 1 shows a front view of the embodiment integrated in the gearing; Fig. 2 shows a sectional view along the line A-A of Fig. 1 ; Fig. 3 shows a front view of the flangable and the freely-installable embodiment; Fig. 4 shows a sectional view along the line A-A of Fig. 3; - Fig. 5 shows a front view of the embodiment having a transmission gearing;

Fig. 6 shows a sectional view along the line A-A of Fig. 5; Fig. 7 shows a view across the current feed cables to the coil and details about an air gap;

Fig. 8 shows a front view of the magnetic bodies in respect of the fastening of the spacer sleeve;

Fig. 9 shows a sectional view along the line A-A of Fig. 8 with respect of the air-gap arrangement;

Fig. 10 shows a view about the distribution of the magnetic flux;

Fig. 11 shows a schematic diagram of the employment of Fig. 5 and Fig. 6; - Figs. 12 a to d show schematic diagrams of different assembly embodiments;

Fig. 13 shows an assembly view of an embodiment of the present invention;

Fig. 14a shows a sectional view of an embodiment of the present invention in towed operation;

Fig. 14b shows details of Fig. 14a in towed operation according to an embodiment of the present invention;

Fig. 15a shows a sectional view of an embodiment of the present invention in braking operation;

Fig. 15b shows details of Fig. 15a in braking operation according to an embodiment of the present invention; - Fig. 16a shows a side view with indicated partition of first and second chambers according to an embodiment of the present invention;

Fig. 16b shows a front view with indicated liquid levels according to an embodiment of the present invention;

Fig. 17 shows a detailed sectional view of the pump with control piston according to another embodiment of the present invention comprising a pump device; Fig. 18a shows a detailed sectional view of the control piston according to another embodiment of the present invention in towed operation;

Fig. 18b shows a detailed sectional view of the control piston according to another embodiment of the present invention in braking operation; - Fig. 19 shows a sectional view with indicated flow directions according to another embodiment of the present invention;

Fig. 20a shows a schematic view of an embodiment of the present invention comprising bypass-borings

Fig. 20b shows a schematic view of an embodiment of the present invention comprising a pump device and a bypass- channel.

Fig. 21 shows an exploded view of a revolution-speed increasor, which is applicable to the eddy current brake of the present invention.

Fig. 22 shows an exploded view of the rotor, particularly the claw pole rotor according to the an embodiment of the present invention. - Fig. 23 shows en exploded view of an embodiment of the present invention.

Fig. 24 shows a sectional view of an eddy current brake according to the present invention.

Fig. 25a shows a sectional view of an embodiment according to the present invention as an "inline-outpuf'-retarder type - Fig. 25b a shows a sectional view of an embodiment according to the present invention as a "wheel-hub"-retarder type. This retarder-type is applicable for front drives and is mounted between rear-wheel-hubs.

Fig. 25c a shows a sectional view of an embodiment according to the present invention as an "driveline"-retarder type for cardan mounting. - Fig. 25d a shows a sectional view of an embodiment according to the present invention as an "outline-outpuf'-retarder type.

Fig. 25e a shows a sectional view of an embodiment according to the present invention as an "inline-inpuf'-retarder type comprising a clutch bell 71.

The induct unit is formed by an induct shaft 2, an energizing coil 3, a coil body 4 and the bolts 5. The induct shaft 2 is screwed together with a housing cap or flange 1 and tensioning nut 14 in a non-contortable manner at one side, while the other side does not have a non-contortable supporting. Thus the induct shaft 2 is additionally forming a support of the rolling element bearings 1 1 and 12, preferably deep-groove ball bearings, for the claw-pole rotor.

The energizing coil 3 including coil body 4 is mounted in the centre of the induct shaft 2 with the bolts 5 in a non-contortable manner. The feeding lines and coil wires, respectively are guided through a conduit E into the inside of the induct shaft 2 and from there they are guided by means of a longitudinal groove F in the bearing seat to the back of the rolling element bearing 12, and then they continue within a protective pipe 23 to the outside of the housing to the control element (Fig. 7). Hence the cables and coil wires, respectively, are not exposed to a mechanical load during the operation in the liquid bath (e.g. shown in Fig. 5 and 6). The induct shaft 2 is made of a ferromagnetic material, preferably pure iron. The energizing coil 3 is preferably made of copper or aluminium, the coil body 4 and the bolt 5 are made of an insulating material having a high heat resistance. In this embodiment it is provided that the energizing coil 3 is arranged between the claw-pole halves 6, 7 for achieving a very high effectiveness.

The claw-pole rotor is forming the dynamic magnetic-field transmission-unit. This one comprises a front claw pole half 6 and a back claw-pole half 7. Both claw-pole halves 6 and 7 are braced together by spacer sleeves 8, which are made of a non-magnetic, but well-weldable material (Fig. 8 and detail E) and additionally by screws 9, preferably stainless steel. The spacer sleeves 8 may also be connected to the claw-pole halves 6 and 7 by other means like gluing, beading or screwing, too. From the technical point of view, spacer sleeves 8 may also be made of ferromagnetic material, which would not affect the functioning with respect to mechanical resistance, but would result in magnetic losses in the air gap by shearing, which in turn causes power losses of the brake.

The claw-pole halves 6 and 7 are made of a ferromagnetic material, preferably pure iron, and are made of massive metal (either milled, forged, punched, cast)or made of layered sheets.

The claw-pole rotor is built up simple and robust and allows a high revolution speed even when having large diameter. There are several operating versions possible, e.g. dry mode or liquid mode, as the claw-pole rotor needs neither coils nor cable lines in order to fulfil its function. Thus even in cold operation damage of the coil and feeding lines caused by viscous lubricant and coolant may not occur.

The induct unit is forming the induct ring 10. This one is moved over the claw-pole halves 6, 7 and is supported within and screwed together, respectively with the housing cap (supporting component) lin a non-contortable manner. Function bound eddy-currents are generated within the induct ring 10 and thus this is the heat generating component, which has to be cooled. Hence the induct ring 10 is preferably located within a sealed housing, in which a cooling conduit is provided, through which the coolant flows, which cools down the outer casing of part 10. The induct ring is preferably made of ferromagnetic material, e.g. pure iron. It is also possible to manufacture the induct ring 10 of a good conducting material and not out of ferromagnetic material, e.g. copper, brass or aluminium. Furthermore it is also possible to manufacture the induct ring 10 of a multi -metal-combination; however, the particular metal share is not limited in any way, so that it is arbitrary and depends on the particular specification of the brake.

In the context of the present invention it is also possible to design eddy-current brakes for large brake torques and small overall size. This is achieved by adding a transmission gearing (Fig. 5 and 6) (i = arbitrary) to the claw-pole rotor to converse the torque and thus operate the brake at a high revolution speed (e.g. 15000 min^"1).

On the one hand the claw-pole rotor generates an alternating magnetic field within the induct ring 10 by pole claws, whose number can be variable, on the other hand the claw-pole rotor transmits the generated brake torque and brake force, respectively, to a shaft and drive system, respectively. The polarity within the individual claw-poles is alternating different, i.e. there exists a plus-terminal / negative-terminal relationship (north/south). Preferably the pole-claws overlap, wherein the overlap is not well-defined, so that it can be variable and with different amount, or it is possible that there is no having a particular magnetic restriction. Thus an initial constant magnetic field is generated within the induct shaft 2, is conducted across extreme small distances (Fig. 7, detail B Sj or Fig. 9 s_v and Sh) via the pole-surfaces of the claw-pole half 6 (Fig. 7, detail C s_a) into the induct ring 10, and is transmitted there into an alternating magnetic field. The magnetic flux is conducted back to the induct shaft 2 via the other claw-pole half 7 and thus closing the magnetic circuit (Fig. 10). It is advantageous that there are no restrictions with respect to installation and different versions of employment, respectively. This is accomplished in that the induct shaft 2 is optionally formed as massive shaft or hollow shaft. In the hollow shaft embodiment a drive shaft 13 (Fig. 2) is put through it. The high magnetism in the centre of the induct shaft 2 causes a magnetisation o the drive shaft 13 as a disadvantage for the system, and it further causes the generation of alternating magnetic fields at the gearwheels of the gearing. The results are eddy-currents, which damage the gear edges, which can result in a breakdown of the gearing. Hence an embodiment of the invention provides for a magnetic decoupling of the drive shaft 13. A non-magnetic material, e.g. stainless steel (austenitic microstructure), titanium or other materials is applicable in dependence of the load level of the drive shaft.

A ferromagnetic material with high coercive field force and with an accordingly low permeability is also possible, which is however only conditionally good for magnetic decoupling. According to the construction only one end of the induct shaft 2 can be supported in a non-contortable manner. Thus one end of said shaft and the stub of said shaft 2, respectively protrudes into the ambiance. In contrast thereto the claw pole rotor is supported at both sides by the induct shaft 2, however even though being supported on both sides it is able to dodge radially, at the unsupported side of part 2. Even with small concentricity aberration the strong magnetic fields would pull the induct shaft together with the claw pole rotor towards the induct ring, , which would result in damages of the components by abrasion. Thus one embodiment of the invention provides a third support in the form of a rolling element bearing, which is supported by another stator (gearing-housing or bearing cap) at the outer ring of the bearing. The inner ring of the bearing braces at the coupling flange 17. It is also possible to achieve a rotatable bearing by a shaft 13 as gearing input shaft or gearing output shaft as well as by bearings already present. So a torsion-free and torsion-rigid second supporting bearing is provided without overdetermination of the bearings. The stator-housing and the bearing cap, respectively, can be adjusted to the load of the support bearing 18 with respect to the mechanical stiffness. Therefore the concentricity aberration is balanced without overloading the supporting bearing.

In all embodiments (e.g. see Fig. 2), all pole faces from the induct shaft 2 to the claw pole halves 6, 7 are aligned with radial surfaces only, the magnetic force in the air gap aligns thereto, thus also extending in radial direction only, which in turn is the reason for being able to decrease the air gaps s, and s_a to a minimum. This raises the magnetic flux density considerably, as the magnetic resistance determines the quality of the magnetic circle. The magnetic resistance and the sheared permeability μ_eff can be calculated from the equation l/μ_eff = l/μ_r + Ϊ_L/I_E- Thus, the air gap (the air gap is defined as the distance between two or more magnets) also determines the necessary power of the coil resulting therefrom and the overall size and current consumption of the energising coil 3. Further an axial loading of the roller element bearings 11 and 12 does not occur. The advantage: radial ball bearings can be used which are much easier to maintain than tapered roller bearings.

It is also possible to align the pole surfaces at the induct shaft 2 and the claw pole halves 6 and 7 according to Fig. 9 with the radial and axial aligned surfaces. The disadvantage of that kind of design is, that the air gaps s_v and Sh have to be constructed considerable larger because of the tolerance-caused axial displacement of the components with respect to each other. This means a higher magnetic overall-resistance and a decreased braking power at the same coil power. The fabrication of the induct shaft 2 and the claw pole halves 6, 7 as well as the assembling of them is also much more complex, costly, the tolerances have to be kept low and it is not possible to check the air gap after assembling.

Referring to the assembling types:

Fig. 1 and 2 show a version of the brake, which is inserted into an existing housing and is fastened by screwing. The drive shaft 13 extends through the brake and is coupled to either a clutch or to a connector of a drive unit. Opposite to the drive side, the force closure to the downstream unit (drive shaft or gearing) is established by a driving collar cogging or a shaft cogging. The considerable advantage results in the downstream gearing can be used as a braking torque converter that the lubrication of the gearing may be used as a common lubrication and as the entire gearing-housing-surface may be used for heat dissipation for cooling the lubricant oil. An prerequisite for said embodiment results in that the respective housing has to be adapted for that purpose.

Fig. 3 and 4 show a version of the brake that on the one hand may be mounted into the drive section, and on the other hand at on the rear side of the gearing or at the front side of the differential gear (driving unit). In contrast to the brake as described in Fig.1 and 2, this version of the brake acts self-sustaining with respect to the common driving units or transmission units, i.e. just minor adaptations are necessary in order to install the brake. The disadvantage can be seen in the greater complexity of the construction.

Fig. 5 and 6 show a version of the brake with transmission gearing with extreme small external dimensions, low weight and high brake torque. This type of brakes is intended for the coupling to wheel hubs at the rear-axles (Fig. 11). Right this technique allows vehicles having a front drive to be equipped with eddy current brakes.

Fig. 11 shows a cooling circuit of the liquid cooling of the eddy current brakes 24. In Fig. 11 the reference number 24 indicates the eddy current brakes (retarder), 25 indicates the drive motor, 26 indicates the cooler and 27 indicates a check valve. A temperature sensor is shown by 28. The flow-cooling-pipe has got the reference number 29 and the runback-cooling-pipe has got the reference number 30. The heat exchanger is indicated by 31.

Fig. 12 a-c schematically show the different assembling versions. Fig. 12a shows an "inline- output"-retarder-type. The retarder 24 is mounted on the rear side of the gearing 32 and is directly connected to the cardan shaft 33. Fig. 12b shows an "inline-output"-retarder-type. The retarder 25 is mounted at the gearing input. This type does not allow such a big brake torque like the output-retarder, but in return the gears are used as brake torque converters. Fig 12c shows an "outline-output"-retarder-type. The retarder 24 is mounted on the side at the gearing output. The transmission of the breaking force to the cardan shaft results from a pair of cogwheels. This type allows extreme big brake torques and is suitable for heavy-duty applications. Fig. 12d shows an "inline - driveline"-retarder type. The retarder 24 is mounted in-between the cardan shaft 33, which connects the gearing 32 with a rear axle (not shown). This type is mainly designed for retrofit-applications, i.e. for upgrading an existing system.

Each of said three types of brakes are based on the identical technique, they only differ in the respective assembling version and mounting version, respectively. Fig. 21 shows an exploded view of a revolution-speed increasor 47, which is applicable to the eddy current brake of the present invention comprising an adapter 58 with sun gear, planetary gearing 59 with drive shaft 20, retaining ring 60, ring gear 61, gearing housing 62. However, other kinds of revolution-speed increasors are also applicable to the eddy current brake according to the present invention.

Fig. 22 shows an exploded view of the rotor, particularly the claw pole rotor according to an embodiment of the present invention comprising retaining ring 63 for ball-bearing 64, ball- bearing 64, screws 65, connection ring rear 66, power supply lines 67, a rear claw pole half 7, energising coil 3, sealing ring 68 for shaft, support disc 69, sliding bearing 70, induct shaft 2, also called magnetic field transducer, front claw pole half 6 and connection ring front 72.

Fig. 23 shows en exploded view of an embodiment of the eddy current brake according to the present invention comprising an induct ring 10, sealing rings 74 for sealing the induct ring 10, o-ring 73, screws 75 for an adapter plate 76, an adapter plate 76 and corresponding o-ring 77 and a tensioning nut 14.

The eddy current brake of the present invention is also provided with an electronic power module (EPM) 41, which is adapted to control and operate the eddy current brake.

Fig. 13 shows an assembly view of an embodiment of the present invention. A first 35 and a second connection 36 is provided to the stator housing for guiding the liquid of the secondary liquid closed loop. A first 38 and a second sensor device 37 is mounted at the stator housing 1 and the second liquid closed loop. A claw pole rotor preferably comprising a multi-part stabilization device and a coil line 40 is inserted into the stator housing 1, which already comprises the induct coil (not shown). An electronic power module (EPM) 41 is fixed at the stator housing 1.

According to the present invention the rotor of the eddy current brake is adapted to transport liquid from the first chamber 43 via the second channel 51 into the second chamber 42 by its rotation. This can be achieved by the centrifugal forces or by particular designs of the rotor and/or the rotor housing or by a combination thereof.

a) level-adjustment via bypass-boring 46 in towed operation

In a preferred embodiment according to the present invention, the control device 34 further comprises a valve 44 having at least one bypass-boring 46 close to or within its valve cap 45. Said bypass-boring 46 is forming a permanent passage so that liquid continuously flows from the second chamber 43 to the first chamber 42.

Fig. 14a shows a sectional view of an embodiment of the present invention in towed operation comprising a stator housing 1, a energizing coil 3 a revolution-speed increasor 47, a first channel 50 a second channel 51, an EPM 41, a first chamber 43 a second chamber 42, a valve 44 and an induct ring 10.

Fig. 14b shows details of Fig. 14a in towed operation according to an embodiment of the present invention comprising a first chamber 43, a second chamber 42, a first channel 50, a valve 44 and bypass-borings 46.

The arrows indicate a permanent liquid flow through the bypass-borings from the second chamber 42 via the first channel 50 into the first chamber 43 comprising the rotor and the revolution-speed increasor 47. Said bypass-borings 46 limit said liquid flow from the second chamber 42 to the first chamber 43 to a predetermined amount of liquid.

The dimensions of said bypass-boring 46 limit the flow from the second chamber 42 to the first chamber 43 at a predetermined flow rate and the flow of the liquid through said bypass- boring 46 correspond to the amount of liquid that is transported back from the first chamber 43 to the second chamber 42 via the second channel 51 by the rotating rotor by e.g. catapulting, with said predetermined flow rate. As a reason of this the liquid-level within the first chamber 43 decreases until a predetermined level is achieved. This is because the immersion depth of the rotor into the liquid bath of the first chamber 43 decreases with decreasing liquid-level and thus the amount of liquid sent back to the second chamber 42 also decreases automatically. In other words, the rotor is just able to transport back the liquid that is mechanically touched or driven by itself. Hence a low immersion depth of the rotor in the liquid bath will cause small transportation rate from the first chamber 43 to the second chamber 42, and a high immersion depth will cause a high transportation rate from the first chamber 43 to the second chamber 42. If the rotor is not able to perform said transportation of liquid, an additional device can be installed and adapted for this purpose.

As a reason of this, the flow through the permanent passages, i.e. the bypass-borings 46 causes a balance between the liquid sent back to the second chamber 42 and the liquid which flows into the first chamber 42 at a desired liquid level. Said desired liquid level is thus adjustable by the design of said at least one bypass-boring 46 alone. It is preferred to get a desired permanent low liquid level within the first chamber 43 and A, preferably not exceeding the half of the rotor from the bottom. More preferably said low level is just enough to provide sufficient lubrication to the moving parts of said eddy current brake and the parts inside the first chamber 43, i.e. preferably said low liquid-level is tangent to the surface of the rotor.

Thus the second chamber 42 comprises more liquid than the first chamber 43, B and this disequilibrium of amount of liquid between first 43 and second chambers 42 is maintained by the rotation of the rotor, which permanently transports liquid back to the second chamber 42.

b) level-adjustment via bypass-boring 46 in braking operation

If the braking operation is initiated as well as at receiving predetermined values or parameters formed of said values at the control device 34, the sensor device causes the control device to open the valve 44 having said at least one bypass-channel 46, e.g. at a predetermined temperature in the first chamber 43 or at a predetermined parameter like a difference or a quotient composed of values from said primary 38 and secondary sensor devices 37. Preferably the valve 44 is opened when the temperature of the secondary liquid closed loop exceeds the temperature of the inside of the first chamber 43 by 10°C, i.e. when the temperature difference between the value of secondary sensor device 37 and the primary sensor device 38 is at least 10⁰C. With opening of said valve 44 the flow restriction from the second chamber 42 into the first chamber 43 is abolished and a maximum amount of liquid flows from the second chamber 42 into the first chamber 43, since the second chamber 42 incorporates more liquid than the first chamber 43 and as long as the liquid level in the second chamber 42 and B is higher than the liquid level on the first chamber 43 and A.

Fig. 15a shows a sectional view of an embodiment of the present invention in braking operation comprising a stator housing 1 , a energizing coil 3 a revolution-speed increasor 47, a first channel 50 a second channel 51, an EPM 41, a first chamber 43 a second chamber 42, a valve 44 and an induct ring 10. Fig. 15b shows details of Fig. 15a in braking operation according to an embodiment of the present invention. The valve 44 has opened the first channel 50 so that a maximum liquid flow can pass through said first channel 50 and can get from the second chamber 42 to the first chamber 43. The arrows indicate said maximum liquid flow in braking operation.

Thus if for example heat increases during braking operation, the first chamber 43 is flooded with liquid and therefore cooled by a maximum heat transmission from the rotor and stator of the first chamber 43 via the liquid to the induct ring 10, which addition can also ally form a heat exchanger, absorbing heat from the first chamber 43 and dissipating said heat by the secondary liquid closed loop.

The maximum achievable liquid flow from the second chamber 42 to the first chamber 43 raises the liquid level within the first chamber 43 and the gearing-area. Indeed the towed losses increase considerably, but this is an additional positive effect to the whole eddy current brake and retarder system, respectively, in braking operation. Heat is transmitted from the primary liquid closed loop to the secondary liquid closed loop via the at least one heat exchanger 56, which preferably provides cooling fins and/or thin-walled liquid channels. The control device 34 is also able to close the valve 44 again, if desired, when e.g. the braking operation is ended or the measured values such as temperature(s), and parameters composed of them, respectively, correspond to a predetermined value. The system operates completely autarkic; high temperature in the first chamber 43 causes high flow-capacity and high heat-dissipation to the secondary liquid closed loop and further causes a high liquid-level within the first chamber 43, where the rotor runs and where the gearing area can also be provided. All components loaded by temperature, are cooled efficiently.

Fig. 16b shows a front view with indicated liquid levels according to an embodiment of the present invention. A and B represent the liquid level in the first and second chambers 42 during towed operation, wherein A represents the liquid level in the first chamber 43 during towed operation and B represents the liquid level in the second chamber 42 during towed operation. Due to the rotation of the rotor the liquid is transported into the second chamber 42 until a equilibrium state between the transportation into the second chamber 42 and the feed flow into the first chamber 43 is achieved. C represents the liquid levels of both the first and second chamber 42s 42, 43 in braking operation since the valve 44 has opened and the liquid levels of first and second chambers 42 are balanced C. The liquid levels are also automatically balanced if the eddy current brake is completely turned off, i.e. when the rotor does not rotate any more and the transporting of liquid back to the second chamber 42 stops while the permanent liquid flow through the bypass-borings will balance the liquid level slowly.

Fig 16 a shows a side view of the eddy current brake and retarder, respectively according to the present invention, where first and second chambers 42 are indicated. The arrows explicitly point to a drawn parting line between the first chamber 43 and the second chamber 42.

Recapitulatory Fig. 20a shows a schematic view of the principle of this embodiment of the present invention comprising bypass-borings.

c) level-adjustment via pump device 48 in towed and braking operation The invention provides another solution for said problem by providing another embodiment according to the present invention, based on the same inventive step. Liquid-level-adjustment can also be implemented by a pump device 48, preferably a gear pump or a vane pump, in combination with a control device 34 comprising a valve 55, preferably a check valve or a control piston 48.

Particularly said embodiment of the present invention is shown in Fig. 17, comprising a stator housing 1, a pump device, a control device 34 with a valve e.g. a control piston 55, a first channel 50, a bypass-channel 49, an outlet of the pump device 54, an inlet of the pump device 53 and a suction channel 52.

According to this embodiment the present invention also provides first and second chambers 42. The first chamber 43 also provides a liquid-bath wherein the rotor of the eddy current brake runs. Preferably the rotor is formed as a claw pole rotor and the second chamber 42 is formed as a liquid-collecting chamber. At least one pump device 48 is provided, whose liquid inlet 53 is connected to the second chamber 42 via a suction channel 52 and whose first part of its liquid outlet 54 is connected to the first chamber 43 via an at least first channel 50. The second part of the liquid outlet 54 is connected to the second chamber 42 via at least one bypass-channel 49. This bypass-channel 49 is controlled by a control device 34 having said valve 55, wherein said valve 55 is adapted to open or close said bypass-channel 49.

This system is also forming a primary liquid closed loop. The number of chambers and channels is also not restricted and has to be adapted corresponding to the respective applications. It is also possible to form a system according to the invention that provides multiple eddy-current brakes and/or multiple chambers and channels, respectively both serial and parallel.

According to the present invention the rotor of the eddy current brake is adapted to transport liquid from the first chamber 43 via the second channel 51 into the second chamber 42 by its rotation. This can be achieved by the centrifugal forces or by particular designs of the rotor and/or the rotor housing or by a combination thereof. Fig. 18a shows a detailed sectional view of the control piston according to this embodiment of the present invention in towed operation. The arrows are indicating the liquid flow from the outlet 54 of the pump device 48 into the first channel 50 and the bypass-channel 49, respectively.

In towed operation the pump device 48 aspirates liquid by a suction channel 52, which connects the second chamber 42 to the liquid inlet of the pump device 48, and pumps it back to the second chamber 42 via a bypass-channel 49. Said bypass-channel 49 connects a first part of the liquid outlet of the pump device 48 with the second chamber 42. A control device 34 controls a valve, preferably a control piston or a check valve, which is installed in said bypass-channel 49, to be in an open position and thus the bypass-channel 49 is open. The liquid pressure that is generated by the pump device 48 at the liquid outlet of the pump is balanced via said bypass-channel 49 with the second chamber 42. Further a first channel 50 is provided connecting a second part of the liquid outlet of the pump device 48 with the first chamber 43. This first channel 50 is adapted to provide a low liquid flow to the first chamber 43. The dimensions of said first channel 50 determine the amount of liquid that is pumped into the first chamber 43, wherein the said amount of liquid is can be predetermined. Preferably said amount of liquid is just sufficient to provide a suitable lubrication to the moving elements within the first chamber 43 when the eddy current brake is in towed operation.

Further said amount of liquid fed to the first chamber 43 is transported back to the second chamber 42 again by the rotor or by a pump or both via a second channel 51 , which connects the first chamber 43 with the second chamber 42. It is obvious that different embodiments of the present invention can be combined if this is desired, i.e. in this embodiment the first channel 50 can also be provided with a valve having bypass-borings like in an above mentioned embodiment.

The dimensions of the bypass-channel 49 are adapted to maintain low liquid pressure at the liquid outlets of the pump device 48 and this requires just a low, still tolerable pump power during towed operation. This embodiment is also provided with a secondary liquid closed loop having at least one heat exchanger 56 and sensor devices like the first embodiment. A first sensor device is adapted to measure values within the first chamber 43 and second sensor device is adapted to measure values in the secondary liquid closed loop.

Fig. 18b shows a detailed sectional view of the control piston 55 according to this embodiment of the present invention in braking operation. The arrows indicate the liquid flow from the outlet of the pump device 54 into the first channel 50. While the control piston 55 of the control device 34 is closing the bypass-channel 49, the first channel 50 is still open and still connected to the outlet of the pump device 48 54, so that liquid is pressed into the first channel 50 in braking operation.

In braking operation the control device 34 closes said valve in reaction of a braking instruction of a user or in reaction of measured values or parameters from the sensor devices. Then the bypass-channel 49 is closed. The liquid pressure, which is generated at the liquid outlet of the pump device 48 increases since a liquid pressure balance via the bypass-channel 49 is not possible any more. As a reason of this the entire power of the pump device 48 pumps liquid through said first channel 50 into the first chamber 43, preferably at predetermined locations within the first chamber 43, e.g. into cavities between the shaft and deflector, which automatically results in a high pressure liquid injection. From there the liquid is directly injected into e.g. the gap between the rotor and the induct ring 10 by predetermined feeding conduits 57 distributed across the periphery of the shaft and with high liquid pressure. High braking power of the eddy current brake and retarder, respectively and thus its resulting heat is transmitted from the induct ring 10 to a secondary liquid closed loop via at least one heat exchanger 56. This technique allows extreme high pump-performances and high pressures, as the drive-power of the pump benefits the braking-power.

Fig. 19 shows a sectional view with indicated flow directions according to another embodiment of the present invention from step a to step f. At step a, the liquid is transferred from the first channel 50 by the pump device 48 into a heat exchanger 56. Step b indicated the feeding of the liquid into the heat exchanger 56. Then the liquid passes the heat exchanger 56 and heat is transferred from said liquid to said heat exchanger 56. At step c the liquid leaves the heat exchanger 56 and is transferred to feeding conduits 57 at predetermined locations within the first chamber 43. Then the liquid is injected into the first chamber 43 at step d, particularly into gaps and slits, respectively, between rotor and stator and induct ring 10, respectively, at predetermined locations within the first chamber 43. At step e the liquid spreads over the surface of the rotor and drops back into the second chamber 42 at step f.

Recapitulatory Fig. 20b shows a schematic view of the principle of this embodiment of the present invention comprising a pump device 48 and a bypass-channel 49.

Fig. 24 shows a sectional view of an eddy current brake according to the present invention. The guiding of the power supply lines within the eddy current brake is protected by a cable protection tube 23. This cable protection tube 23 is located in the induct shaft and magnetic field transducer, respectively 2. This location is possible since the induct shaft 2is not part of the rotating elements but part of the static elements of the eddy current brake. Thus, in an embodiment of the present invention, the power is supplied axle-sided into the energising coil 3. As a result of this, the power supply of the eddy current brake according to the present invention can be connected fixedly. Therefore, no sliding contacts are needed according to the present invention. Additionally, the power supply lines and coil lines 40, respectively, do not run the risk of contacting any liquids of primary or secondary liquid closed loops.

Hence the first solution of above said problem of the invention is based on bypass-borings together with the opening of a valve while the second solution is based on a pumping system together with a closing of a valve.

In an preferred embodiment of the present invention the rotor, preferably a claw pole rotor, and the induct ring 10 as well as the magnetic field, are aligned axially. It is also possible to align the magnetic field assembling radially.

The claw poles of the rotor and their blades, respectively, are subjected to strong radial outward-deformation due to the strong magnetic fields and the extensive centrifugal forces. Thus, claw poles are not applicable to eddy current brakes due to said reasons in prior art. However, with respect to the high power density and the simple design, claw pole rotors outclass the single pole rotors.

For this reasons the present invention provides a stabilization device made of non-magnetic material to stabilize the pole blades, which prevents radial outward-deformation in spite of the high magnetic fields and the centrifugal forces. Said stabilization device can be formed one-piece or multi-part. One embodiment of the present invention comprises a multi-part stabilization device, particularly a two-piece stabilization device having fixing means.

At the front and the rear, two connection rings made of non-magnetic material are screwed together respectively once with the flange ring and once with the pole blade. The connection ring prevents radial deformation. The cross-section of the connection rings is aligned with the present tractive force in such a manner that an overexpansion within the material can be prevented.

The combination of different metals in the induct ring 10 is additionally provided with a corrosion protection, at desired areas of the eddy current brake or at the whole eddy current brake. This causes long-lasting and constant-good convection properties. However, the kind of corrosion protection and the area to be provided with is dependent on the different fields of applications and the corresponding application conditions. Thus the corrosion protection has to be adapted accordingly.

Due to the design the rotors of windmills and wind turbines, respectively already take benefit from low wind forces. However, these wind turbines have an overrun of power from major wind forces, which can not be absorbed by the generator any more. Thus windmills have to be turned off at higher wind speeds. Hence valuable energy is lost. Efforts to efficiently use retarders and eddy current brakes, respectively, of prior art for windmills, failed, since the retarders of prior art can not provide the required high brake torque at low revolution speed. Additionally, this would result in massive thermal problems due to the inefficient air-cooling- technique according to prior art. Therefore the present invention provides a water-cooled eddy current brake with revolution- increasor, wherein the retarder is located radially around the revolution-increasor-gearing in order to achieve the required brake torque. Hence about the fourfold brake torque is achievable with low effort, e.g. 4000 Nm per retarder, taken four times results in 16000 Nm of brake torque. Additionally the brake-power is relatively low due to the low revolution- speed of the rotor hub, so that thermal problems can be prevented.

On the one hand aircrafts have small-sized brakes with respect to their overall weight, which abrade quickly. On the other hand it has to be considered that said overall weight is an essential criterion for dimensioning of the brake disks. Thus importance is just attached to the categorical function when they are developed while the sustained-action brake features are neglected. This technical problem can be solved by high-performance retarder technology according to the present invention, when a person skilled in the art applies the present invention to the respective specifications of the aircraft industry, particularly with respect to the high brake torque of the present invention in combination with minimal size and weight.

Using the retarder of the present invention in combination with a power reclamation system in a hybrid system:

Nowadays hybrid systems are getting more and more important, because the fuel-saving effect is perceptible compared with common petrol-engined or diesel-engined vehicles. Although the electric drive by an three-phase-motor as well as the power generation via three-phase-generator has essential disadvantages. The battery just stores and emits direct current. At driving the translating from direct current into alternating current is inhered with enormous technical costs and power-losses. This means that much more power drawn from the battery than needed for the drive, while the rest is lost heat. Another problem is the low sustained-action brake effort due to the volitional sub-dimensioning of the engine with respect to the quite high weight of the vehicle. The generator just generates sufficient brake force as long as the battery is not charged completely. The brake force decreases considerably the fuller the battery is charged and the brake force disappears completely, if the battery is fully charged. In order to eliminate said disadvantages the present invention is adaptive in a combined system, wherein the electric motor and the generator are additionally coupled to retarder. If the brake force of the generator decreases, the retarder takes over its braking-task. This kind of system is advantageous in the area of commercial vehicles, particularly in the area of passenger transportation, when the sustained-action brake requirements have to be accomplished.

The present invention discloses a liquid-cooled eddy current brake and retarder, respectively for retarding a shaft and axis, respectively, of a vehicle or a drive of all kind by a claw pole rotor as a magnetic-field-transmitting and force-taking unit, driven by said shaft and axis, respectively, a unit formed as a stator and an induct ring 10 formed as a stator, in which one of said three components comprises the inducing component of the eddy current brake, one of said three components comprises the induced component of the eddy current brake and one of said components comprises the force-transmitting component of the eddy current brake, characterized in that the inducing components and the induced component of the eddy current brake are arranged statically and fixedly, respectively, and the force-transmitting components are arranged dynamically and rotatably, respectively.

The eddy current brake is further characterized in that the induct shaft 2 is non-contortably connected at one side to a housing or a support flange 1 and the bearing of the claw pole rotor is effected by the induct shaft 2. The eddy current brake is further characterized in that one end of the induct shaft 2 comprises an additional rotatable bearing 18 by means of further mechanical supplying means. The eddy current brake is further characterized in that the magnetic field can be transmitted across a gap (S_J, s_v, S_h), arranged in radial or axial direction, from the induct shaft 2 via the claw pole rotor further via a gap (s_a), which is arranged in radial direction, to the induct ring 10.

The eddy current brake is further characterized in that the transmission of the magnetic field from the induct shaft 2 to the front claw pole half 6 and back via the rear claw pole half 7 into the induct shaft 2 is carried out in form of a constant magnetic field, in which the direction of the flow can also be inverse. The eddy current brake is further characterized in that the claw pole rotor 6, 7 generates a differing polarity over the respective pole surfaces of the pole claws and thereby a alternating magnetic field can be generated within the induct ring 10. The eddy current brake is further characterized in that the induct ring 10 comprises a multi-metal-combination in order to determine the depth of magnetic penetration, wherein the respective metal-portion is variable.

The eddy current brake is further characterized in that the energising coil 3 is non-contortably supported on the induct shaft 2. The eddy current brake is further characterized in that in that the energising coil 3 is arranged between the claw pole halves 6, 7. The eddy current brake is further characterized in that bores and conduits E, respectively or cavities and longitudinal grooves F, respectively are provided in the induct shaft 2 for the lines of the power supply to the energising coil(s) 3.

The eddy current brake is further characterized in that a protection tube 23 is provided for protecting the coil supply lines. The eddy current brake is further characterized in that the induct shaft 2 is selectively formed as a solid shaft or as a hollow shaft. The eddy current brake is further characterized in that another shaft 13 is positioned through the central bore of the induct shaft 2, which serves for driving. The eddy current brake is further characterized in that the shaft 13, which serves as drive shaft is formed of a non-magnetic steel or of a non-magnetic material, which is adapted to the load. The eddy current brake is further characterized in that a transmission gearing is connected upstream the claw pole rotor for increasing the revolution speed.

The eddy current brake is further characterized in that the cogwheel assembly of the transmission gearing can be directly coupled to the coupling flange 13 by a detachable shaft connection or an additional cogwheel. The eddy current brake is further characterized in that the detachable shaft connection or the sun gear of a planetary gear set is also selectively provided as support bearing for the induct shaft 2.

The present invention also discloses an eddy current brake further comprising a primary liquid closed loop, wherein the primary liquid closed loop comprises a first chamber 43 providing a liquid bath at least a second chamber 42 at least a first channel 50 from the second chamber 42 into the first chamber 43 at least a second channel 51 from the first chamber 43 to the second chamber 42 at least a control device 34 that controls the flow rate of liquid from the second chamber 42 through the first channel 50 to the first chamber 43, wherein the control device 34 comprises a valve which is installed in the first channel 50.

The eddy current brake is further characterized in that the valve is closed, partly opened or completely opened by the control device 34. The eddy current brake is further characterized in that the valve comprises at least one bypass-boring, which is still permeable, when the valve is closed , so that liquid is able to flow from the first chamber 43 to the second chamber 42. The eddy current brake is further characterized in that said bypass-boring is dimensioned in a manner that the liquid level of the liquid bath in the first chamber 43 is maintained at a low level by limiting the inflow from the second chamber 42 into the first chamber 43.

The eddy current brake is further characterized in that the bypass-boring is configured in a manner that the amount of inflow from the second chamber 42 through the bypass-boring into the first chamber 43 corresponds to a predetermined amount. The eddy current brake is further characterized in that the at least one bypass-boring is configured in a manner that the amount of inflow of the liquid from the second chamber 42 into the first chamber 43 is limited to an amount of liquid, that corresponds to an amount of liquid which is transported back from the first chamber 43 through the second channel 51 into the second chamber 42.

The present invention also discloses an eddy current brake and retarder, respectively further comprising a primary liquid closed loop, wherein the primary liquid closed loop comprises a first chamber 43 providing a liquid bath at least a second chamber 42 at least one pump device 48, whose liquid input is connected to the second chamber 42 via an suction channel and whose first part of its liquid output is connected to the first chamber 43 via an at least first channel 50 at least a second channel 51 from the first chamber 43 into the second chamber 42 at least one bypass-channel 49 which connects the second part of the liquid output of the pump device 48 to the second chamber 42 at least one control device 34, which controls the flow rate of the liquid of the liquid output through the bypass-channel 49 into the second chamber 42, wherein the control device 34 comprises a valve, which is installed in the bypass-channel 49.

The eddy current brake is further characterized in that the first channel 50 is configured in a manner that the amount of inflow of the liquid from the second chamber 42 via the pump device 48 through the second chamber 42 into the first chamber 43 corresponds to a predetermined amount. The eddy current brake is further characterized in that the rotor is configured additionally in a manner so that the rotor transports liquid from the first chamber 43 via the second channel 51 back to the second chamber 42 by rotation. The eddy current brake is further characterized in that the rotor is positioned in the first chamber 43 in a manner that a low liquid level in the first chamber 43 does not exceed the half height of the rotor. The eddy current brake is further characterized in that the rotor at least touches the liquid level of the liquid bath in the first chamber 43 or at least partly dips into the liquid bath. The eddy current brake is further characterized in that the amount of liquid transported back to the second chamber 42 is determined by the immersion depth of the rotor into the liquid bath.

The eddy current brake is further characterized in that the amount of liquid transported back to the second chamber 42 is larger at large immersion depth of the rotor into the liquid bath than at small immersion depth of the rotor into the liquid bath. The eddy current brake is further characterized in that large immersion depth of the rotor into the liquid bath corresponds to a high liquid level in the first chamber 43 and small immersion depth of the rotor into the liquid bath corresponds to a low liquid level in the first chamber 43. The eddy current brake is further characterized in that the amount of liquid transported back to the second chamber 42 via the second channel 51 can not exceed a predetermined amount of liquid.

The eddy current brake is further characterized in that at a predetermined value the amount of liquid, which is transported back to the second chamber 42 by the rotor corresponds to the amount of inflow of the liquid from the second chamber 42 through the bypass-boring and the first channel 50, respectively. The eddy current brake is further characterized in that the valve is closed, partly opened or completely opened by the control device 34. The eddy current brake is further characterized in that the pump device 48 is driven by the rotor mechanically. The eddy current brake is further characterized in that the pump device 48 is configured to generate liquid pressure at the liquid output.

The eddy current brake is further characterized in that the bypass-channel 49 is configured to relieve the pressure at the liquid output of the pump device 48 by liquid pressure equalisation with the second chamber 42, when the valve is at least partly opened. The eddy current brake is further characterized in that one or more outlet locations of the first channel 50 are arranged to inject liquid directly into the first chamber 43 at predetermined locations. The eddy current brake is further characterized in that the inject pressure of the liquid via the first channel 50 into the first chamber 43 is higher, when the valve is closed, than when the valve is at least partly opened. The eddy current brake is further characterized in further comprising a first sensing device, which comprises one or more sensors and is adapted to measure values in the first chamber 43. The eddy current brake is further characterized in that the sensor device at least comprises a temperature sensor.

The eddy current brake is further characterized in that the sensor device is configured to cause the control device 34 to open or close the valve, when one or more measured values respectively correspond to one or more predetermined values. The eddy current brake is further characterized in further comprising a secondary liquid closed loop having at least a heat exchanger 56 in order to take heat from the primary liquid closed loop. The eddy current brake is further characterized in that the secondary liquid closed loop comprises a second sensor device, which comprises one or more sensors and is adapted to measure values in the secondary liquid closed loop. The eddy current brake is further characterized in that the sensor device is configured to open or close the valve, when a parameter composed of the values of the first and second sensor devices correspondents to a predetermined value.

The eddy current brake is further characterized in that said parameter is a difference or a quotient.

The eddy current brake is further characterized in that the values measured by the sensor device comprise temperature, pressure, liquid level, viscosity, syncrisis of the liquid, volume of the liquid, flow speed of the liquid or a combination thereof. The present invention also discloses a method for controlling a liquid level in a liquid cooled eddy current brake having a rotor and a stator, comprising maintaining a first liquid level in a first chamber 43, when the eddy current brake is not activated, and maintaining a second liquid level in a first chamber 43, when the eddy current brake is activated.

The method is further characterized in maintaining of a first liquid level in the first chamber 43, when the eddy current brake is not activated, comprises closing of a valve in a first channel 50 from the second chamber 42 to the first chamber 43, wherein the valve comprises at least one bypass-boring, which form a defined and permanent opening permanent feeding a constant amount of liquid from the second chamber 42 into the first chamber 43 comprising a liquid bath having a liquid level and the rotor running therein, via the first permanent opening transporting back a part of the amount of liquid from the first chamber 43 to the second chamber 42 by the rotor, wherein the part of the amount of liquid transported back to the second chamber 42 depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber 42 is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber 42 is not less than the permanently fed constant amount of liquid self- controlled balancing of the part of liquid transported back and the continuously fed amount of liquid as soon as a predetermined value of the liquid level in the first chamber 43 is achieved.

The method is further characterized in maintaining of a second liquid level in the first chamber 43, when the eddy current brake is activated, comprises at least partly opening of a valve in a first channel 50 from the second chamber 42 to the first chamber 43, wherein the valve comprises at least one bypass-boring, which form a defined and permanent opening, in order to feed a maximum amount of liquid to the first chamber 43, wherein said maximum amount of liquid is larger than the amount of liquid fed through the bypass-boring alone permanent feeding a constant amount of liquid from the second chamber 42 into the first chamber 43 comprising a liquid bath having a liquid level and the rotor running therein, via the first permanent opening transporting back a part of the amount of liquid from the first chamber 43 to the second chamber 42 by the rotor, wherein the part of the amount of liquid transported back to the second chamber 42 depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber 42 is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein said maximum amount of liquid fed to the first chamber 43 is not less than the permanently amount of liquid transported back to the second chamber 42 self-controlled balancing of the part of liquid transported back and the maximum amount of liquid fed to the first chamber 43 as soon as a predetermined value of the liquid level in the first chamber 43 is achieved, wherein the predetermined value is higher than when the valve is closed.

The method is further characterized in maintaining of a first liquid level in the first chamber 43, when the eddy current brake is not activated, comprises opening a valve in a bypass- channel 49 from the liquid output of a pump device 48 to the second chamber 42 wherein the liquid input of the pump device 48 is connected to the second chamber 42 and wherein the liquid output of the pump device 48 is connected to the bypass-channel 49 as well as to a first channel 50 to the first chamber 43 balancing of the liquid pressure, which is generated by the pump device 48 at the liquid output, by the bypass-channel 49 permanent feeding a constant amount of liquid through the first channel 50 into the first chamber 43 comprising a liquid bath having a liquid level, and the rotor running therein transporting back a part of the amount of liquid from the first chamber 43 to the second chamber 42 by the rotor, wherein the part of the amount of liquid transported back to the second chamber 42 depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber 42 is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber 42 is not less than the permanently fed constant amount of liquid self-controlled balancing of the part of liquid transported back and the continuously fed amount of liquid as soon as a predetermined value of the liquid level in the first chamber 43 is achieved. The method is further characterized in maintaining of a second liquid level in the first chamber 43, when the eddy current brake is not activated, comprises at least partly closing a valve in a bypass-channel 49 from the liquid output of a pump device 48 to the second chamber 42 wherein the liquid input of the pump device 48 is connected to the second chamber 42 and wherein the liquid output of the pump device 48 is connected to the bypass- channel 49 as well as to a first channel 50 to the first chamber 43 generating a liquid pressure at the liquid output by the pump device 48 injecting of a maximum amount of liquid by the liquid pressure via the first channel 50 into the first chamber 43 transporting back a part of the amount of liquid from the first chamber 43 to the second chamber 42 by the rotor, wherein the part of the amount of liquid transported back to the second chamber 42 depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber 42 is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein maximum amount of liquid injected to the first chamber 43 is not less than the permanently amount of liquid transported back self-controlled balancing of the part of liquid transported back and the maximum amount of liquid injected into the first chamber 43 as soon as a predetermined value of the liquid level in the first chamber 43 is achieved.

List of reference numbers:

1 stator-housing or housing-cap

2 induct shaft

3 energising coil

4 coil body

5 bolt

6 front claw pole half

7 rear claw pole half

8 spacer sleeve

9 screw

10 induct ring

11 rolling element bearing front

12 rolling element bearing rear

13 drive shaft

14 tensioning nut

15 shaft sealing

16 gearing housing

17 coupling flange

18 support bearing for induct shaft

19 transmission gearing

20 drive shaft

21 bearing for drive shaft

22 front cap

23 cable-protection tube

24 eddy current brake

25 drive motor

26 cooler

27 check valve

28 temperature sensor

29 flow-cooling-pipe 30 runback-cooling-pipe

31 heat exchanger

32 gearing

33 cardan shaft 34 control device

35 inlet for liquid of the secondary liquid closed loop

36 outlet for liquid of the secondary liquid closed loop

37 secondary sensor device for secondary liquid closed loop

38 primary sensor device for primary liquid closed loop 39 stabilisation device

40 coil line

41 electronic power module (EPM)

42 second chamber

43 first chamber 44 valve having bypass-borings

45 valve cap

46 bypass-boring

47 revolution speed increasor

48 pump device 49 bypass-channel

50 first channel

51 second channel

52 suction channel

53 inlet of the pump device 54 outlet of the pump device

55 valve and control piston, respectively, in the bypass-channel

56 heat exchanger

57 feeding conduit

58 adapter with sun gear 59 planetary gearing

60 retaining ring

61 ring gear 62 gearing housing

63 retaining ring for claw pole rotor

64 ball-bearing

65 screw 66 connection ring rear

67 power supply lines

68 sealing ring for shaft

69 support disc

70 sliding bearing 71 clutch bell

72 connection ring front

73 o-ring

74 sealing rings for sealing the induct ring

75 screw for adapter plate 76 adapter plate

77 o-ring for adapter plate

A liquid level in the first chamber during towed operation

B liquid level in the second chamber during towed operation

C liquid level in both chambers during braking operation and idleness

Claims

Claims:

1. Liquid-cooled eddy current brake for retarding a shaft and axis, respectively, of a vehicle or a drive of all kind by a claw pole rotor as a magnetic-field-transmitting and force-taking unit, driven by said shaft and axis, respectively, a unit formed as a stator and an induct ring formed as a stator, in which one of said three components comprises the inducing component of the eddy current brake, one of said three components comprises the induced component of the eddy current brake and one of said components comprises the force-transmitting component of the eddy current brake, characterized in that the inducing components and the induced component of the eddy current brake are arranged statically and fixedly, respectively, and the force-transmitting components are arranged dynamically and rotatably, respectively.

2. Eddy current brake according to claim 1 , characterized in that the induct shaft (2) is non-contortably connected at one side to a housing or a support flange (1) and the bearing of the claw pole rotor is effected by the induct shaft (2).

3. Eddy current brake according to claim 1 and 2, characterized in that one end of the induct shaft (2) comprises an additional rotatable bearing (18) by means of further mechanical supplying means.

4. Eddy current brake according to one of claim 1 to 3, characterized in that the magnetic field can be transmitted across a gap (s,, s_v, Sh), arranged in radial or axial direction, from the induct shaft (2) via the claw pole rotor further via a gap (s_a), which is arranged in radial direction, to the induct ring (10).

5. Eddy current brake according to claim 4, characterized in that the transmission of the magnetic field from the induct shaft (2) to the front claw pole half (6) and back via the rear claw pole half (7) into the induct shaft (2) is carried out in form of a constant magnetic field, in which the direction of the flow can also be inverse.

6. Eddy current brake according to claim 4 or 5, characterized in that the claw pole rotor (6, 7) generates a differing polarity over the respective pole surfaces of the pole claws and thereby a alternating magnetic field can be generated within the induct ring (10).

7. Eddy current brake according to claim 6, characterized in that the induct ring (10) comprises a multi-metal-combination in order to determine the depth of magnetic penetration, wherein the respective metal-portion is variable.

8. Eddy current brake according to one of claim 1 to 7, characterized in that the energising coil (3) is non-contortably supported on the induct shaft (2).

9. Eddy current brake according to one of claim 1 to 8, characterized in that the energising coil (3) is arranged between the claw pole halves (6, 7).

10. Eddy current brake according to claim 8 or 9, characterized in that bores and conduits (E), respectively or cavities and longitudinal grooves (F), respectively are provided in the induct shaft (2) for the lines of the power supply to the energising coil(s) (3).

11. Eddy current brake according to claim 10, characterized in that a protection tube (23) is provided for protecting the coil supply lines.

12. Eddy current brake according to claim 1 to 11, characterized in that the induct shaft (2) is selectively formed as a solid shaft or as a hollow shaft.

13. Eddy current brake according to claim 12, characterized in that another shaft (13) is positioned through the central bore of the induct shaft (2), which serves for driving.

14. Eddy current brake according to claim 12 or 13, characterized in that the shaft (13), which serves as drive shaft is formed of a non-magnetic steel or of a non-magnetic material, which is adapted to the load.

15. Eddy current brake according to one of claim 1 to 14, characterized in that a transmission gearing is connected upstream the claw pole rotor for increasing the revolution speed.

16. Eddy current brake according to claim 15, characterized in that the cogwheel assembly of the transmission gearing can be directly coupled to the coupling flange (13) by a detachable shaft connection or an additional cogwheel.

17. Eddy current brake according to claim 15, characterized in that the detachable shaft connection or the sun gear of a planetary gear set is also selectively provided as support bearing for the induct shaft (2).

18. Eddy current brake according to claim 1 to 17 further comprising a primary liquid closed loop, wherein the primary liquid closed loop comprises: a first chamber providing a liquid bath; at least a second chamber; at least a first channel from the second chamber into the first chamber; at least a second channel from the first chamber to the second chamber; at least a control device that controls the flow rate of liquid from the second chamber through the first channel to the first chamber, wherein the control device comprises a valve which is installed in the first channel.

19. Eddy current brake according to claim 18, wherein the valve is closed, partly opened or completely opened by the control device.

20. Eddy current brake according to claim 18 or 19, wherein the valve comprises at least one bypass-boring, which is still permeable, when the valve is closed , so that liquid is able to flow from the first chamber to the second chamber.

21. Eddy current brake according to claim 20, wherein said bypass-boring is dimensioned in a manner that the liquid level of the liquid bath in the first chamber is maintained at a low level by limiting the inflow from the second chamber into the first chamber.

22. Eddy current brake according to claim 21, wherein the bypass-boring is configured in a manner that the amount of inflow from the second chamber through the bypass-boring into the first chamber corresponds to a predetermined amount.

23. Eddy current brake according to claim 21 to 24, wherein the at least one bypass- boring is configured in a manner that the amount of inflow of the liquid from the second chamber into the first chamber is limited to an amount of liquid, that corresponds to an amount of liquid which is transported back from the first chamber through the second channel into the second chamber.

24. Eddy current brake according to claim 1 to 17 further comprising a primary liquid closed loop, wherein the primary liquid closed loop comprises: a first chamber providing a liquid bath; at least a second chamber; at least one pump device, whose liquid input is connected to the second chamber via an suction channel and whose first part of its liquid output is connected to the first chamber via an at least first channel; at least a second channel from the first chamber into the second chamber; at least one bypass-channel which connects the second part of the liquid output of the pump device to the second chamber; at least one control device, which controls the flow rate of the liquid of the liquid output through the bypass-channel into the second chamber, wherein the control device comprises a valve, which is installed in the bypass-channel.

25. Eddy current brake according to claim 24, wherein the first channel is configured in a manner that the amount of inflow of the liquid from the second chamber via the pump device through the second chamber into the first chamber corresponds to a predetermined amount.

26. Eddy current brake according to claim 18 to 25, wherein the rotor is configured additionally in a manner so that the rotor transports liquid from the first chamber via the second channel back to the second chamber by rotation.

27. Eddy current brake according to claim 18 to 26, wherein the rotor is positioned in the first chamber in a manner that a low liquid level in the first chamber does not exceed the half height of the rotor.

28. Eddy current brake according to claim 18 to 27, wherein the rotor at least touches the liquid level of the liquid bath in the first chamber or at least partly dips into the liquid bath.

29. Eddy current brake according to claim 25 to 28, wherein the amount of liquid transported back to the second chamber is determined by the immersion depth of the rotor into the liquid bath.

30. Eddy current brake according to claim 29, wherein the amount of liquid transported back to the second chamber is larger at large immersion depth of the rotor into the liquid bath than at small immersion depth of the rotor into the liquid bath.

31. Eddy current brake according to claim 29 or 30, wherein large immersion depth of the rotor into the liquid bath corresponds to a high liquid level in the first chamber and small immersion depth of the rotor into the liquid bath corresponds to a low liquid level in the first chamber.

32. Eddy current brake according to claim 26 to 31, wherein the amount of liquid transported back to the second chamber via the second channel can not exceed a predetermined amount of liquid.

33. Eddy current brake according to claim 26, wherein at a predetermined value the amount of liquid, which is transported back to the second chamber by the rotor corresponds to the amount of inflow of the liquid from the second chamber through the bypass-boring and the first channel, respectively.

34. Eddy current brake according to claim 24 to 33, wherein the valve is closed, partly opened or completely opened by the control device.

35. Eddy current brake according to claim 24 to 34, wherein the pump device is driven by the rotor mechanically.

36. Eddy current brake according to claim 24 to 35, wherein the pump device is configured to generate liquid pressure at the liquid output.

37. Eddy current brake according to claim 24 to 36, wherein the bypass-channel is configured to relieve the pressure at the liquid output of the pump device by liquid pressure equalisation with the second chamber, when the valve is at least partly opened.

38. Eddy current brake according to claim 24 to 37, wherein one or more outlet locations of the first channel are arranged to inject liquid directly into the first chamber at predetermined locations.

39. Eddy current brake according to claim 38, wherein the inject pressure of the liquid via the first channel into the first chamber is higher, when the valve is closed, than when the valve is at least partly opened.

40. Eddy current brake according to claim 18 to 39, further comprising a first sensing device, which comprises one or more sensors and is adapted to measure values in the first chamber.

41. Eddy current brake according to claim 18 to 40, wherein the sensor device at least comprises a temperature sensor.

42. Eddy current brake according to claim 18 to 41, wherein the sensor device is configured to cause the control device to open or close the valve, when one or more measured values respectively correspond to one or more predetermined values.

43. Eddy current brake according to claim 18 to 42, further comprising a secondary liquid closed loop having at least a heat exchanger in order to take heat from the primary liquid closed loop.

44. Eddy current brake according to claim 43, wherein the secondary liquid closed loop comprises a second sensor device, which comprises one or more sensors and is adapted to measure values in the secondary liquid closed loop.

45. Eddy current brake according to claim 43 or 44, wherein the sensor device is configured to open or close the valve, when a parameter composed of the values of the first and second sensor devices correspondents to a predetermined value.

46. Eddy current brake according to claim 45, wherein said parameter is a difference or a quotient.

47. Eddy current brake according to claim 40 to 46, wherein the values measured by the sensor device comprise temperature, pressure, liquid level, viscosity, syncrisis of the liquid, volume of the liquid, flow speed of the liquid or a combination thereof.

48. Method for controlling a liquid level in a liquid cooled eddy current brake having a rotor and a stator, comprising: maintaining a first liquid level in a first chamber, when the eddy current brake is not activated, and maintaining a second liquid level in a first chamber, when the eddy current brake is activated.

49. Method according to claim 48, wherein the maintaining of a first liquid level in the first chamber, when the eddy current brake is not activated, comprises: closing of a valve in a first channel from the second chamber to the first chamber, wherein the valve comprises at least one bypass-boring, which form a defined and permanent opening; permanent feeding a constant amount of liquid from the second chamber into the first chamber comprising a liquid bath having a liquid level and the rotor running therein, via the first permanent opening; transporting back a part of the amount of liquid from the first chamber to the second chamber by the rotor, wherein the part of the amount of liquid transported back to the second chamber depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber is not less than the permanently fed constant amount of liquid; self-controlled balancing of the part of liquid transported back and the continuously fed amount of liquid as soon as a predetermined value of the liquid level in the first chamber is achieved.

50. Method according to claim 48, wherein the maintaining of a second liquid level in the first chamber, when the eddy current brake is activated, comprises: at least partly opening of a valve in a first channel from the second chamber to the first chamber, wherein the valve comprises at least one bypass-boring, which form a defined and permanent opening, in order to feed a maximum amount of liquid to the first chamber, wherein said maximum amount of liquid is larger than the amount of liquid fed through the bypass-boring alone; permanent feeding a constant amount of liquid from the second chamber into the first chamber comprising a liquid bath having a liquid level and the rotor running therein, via the first permanent opening; transporting back a part of the amount of liquid from the first chamber to the second chamber by the rotor, wherein the part of the amount of liquid transported back to the second chamber depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein said maximum amount of liquid fed to the first chamber is not less than the permanently amount of liquid transported back to the second chamber; self-controlled balancing of the part of liquid transported back and the maximum amount of liquid fed to the first chamber as soon as a predetermined value of the liquid level in the first chamber is achieved, wherein the predetermined value is higher than when the valve is closed.

51. Method according to claim 48, wherein the maintaining of a first liquid level in the first chamber, when the eddy current brake is not activated, comprises: opening a valve in a bypass-channel from the liquid output of a pump device to the second chamber wherein the liquid input of the pump device is connected to the second chamber and wherein the liquid output of the pump device is connected to the bypass-channel as well as to a first channel to the first chamber; balancing of the liquid pressure, which is generated by the pump device at the liquid output, by the bypass-channel; permanent feeding a constant amount of liquid through the first channel into the first chamber comprising a liquid bath having a liquid level, and the rotor running therein; transporting back a part of the amount of liquid from the first chamber to the second chamber by the rotor, wherein the part of the amount of liquid transported back to the second chamber depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber is not less than the permanently fed constant amount of liquid; self-controlled balancing of the part of liquid transported back and the continuously fed amount of liquid as soon as a predetermined value of the liquid level in the first chamber is achieved

52. Method according to claim 48, wherein the maintaining of a second liquid level in the first chamber, when the eddy current brake is not activated, comprises: at least partly closing a valve in a bypass-channel from the liquid output of a pump device to the second chamber wherein the liquid input of the pump device is connected to the second chamber and wherein the liquid output of the pump device is connected to the bypass-channel as well as to a first channel to the first chamber; generating a liquid pressure at the liquid output by the pump device; injecting of a maximum amount of liquid by the liquid pressure via the first channel into the first chamber; transporting back a part of the amount of liquid from the first chamber to the second chamber by the rotor, wherein the part of the amount of liquid transported back to the second chamber depends on the immersion depth of the rotor in the liquid bath, and wherein the part of the amount of liquid transported back to the second chamber is larger at high immersion depth of the rotor in the liquid bath than at small immersion depth of the rotor in the liquid bath, and wherein maximum amount of liquid injected to the first chamber is not less than the permanently amount of liquid transported back; self-controlled balancing of the part of liquid transported back and the maximum amount of liquid injected into the first chamber as soon as a predetermined value of the liquid level in the first chamber is achieved.