DE19652831B4 - Pressure fluid feed system for the supply of high pressure manifolds - Google Patents

Abstract

Pressure fluid supply system, in particular for the supply of high pressure manifolds (common rail systems) such. B. of injection systems for internal combustion engines, with a supplied by a low-pressure feed pump high-pressure stage, the excess amount of pressurized fluid by means of a leakage and / or Druckfluidbegrenzungseinrichtung in a return line (188; 189; 288; 289; 388; 389; 489; 589) throttled and whose pump unit (190; 290; 390; 490; 590) is incorporated in a cooling oil flow (186; 187; 286; 287; 396; 397; 387; 496; 497; 487; 596; 597; 587), wherein Shut off the connection between the low pressure feed pump (110; 210; 310; 410; 510) and the high pressure stage (190; 290; 390; 490; 590) a directional control valve (171; 271; 394; 494; 595) is disposed therethrough characterized in that the return flow line (188; 189; 288; 289; 388; 389; 489; 589) and / or the cooling oil flow (287) flowing from the pump unit (190; 290; 390; 490; 590) at least partially into the suction side ( 155; 255; 355; 455; 555) of the high pressure pump (190; 290; 390; 490; 590) downstream of the low pressure feed pump (110; 10, 310, 410; 510) can be fed in ...

Description

The The invention relates to a pressurized fluid supply system, in particular for the supply of high pressure manifolds (common rail systems) such. B. from Injection systems for Internal combustion engines, according to the preamble of claim 1

Such a pressurized fluid feed system is z. B. from the DE 41 26 640 A1 known. In addition to the injection system usually also includes a number of preferably electromagnetically actuated injectors, which are controlled according to the current operating mode and the present load profile of the internal combustion engine. The system pressure in the common high-pressure manifold (common rail) is adjusted by a preferably electrically adjustable pressure limiting valve (DBE valve) integrated in the pump housing, the excess amount of pressurized fluid being throttled via this DBE valve via a return line to the tank. While the low-pressure feed pump, which is usually formed by a vane or a roller cell pump, only a small mechanical and thermal stress is exposed, the pump of the high-pressure stage is regularly a very high mechanical and thus thermal stress. In the pressurized fluid supply system according to DE 41 26 640 A1 Therefore, it is envisaged that those areas of the pump main stage, which are subject to increased thermal and / or mechanical stress, are included in a cooling oil flow, which is derived from the excess fluid amount of the low-pressure feed pump and fed to the tank.

The DE 69 16 890 U discloses a pressurized fluid supply system in which the cooling oil flow is not connected back into the fuel tank, but via a return line to the suction line or to the suction of the low-pressure feed pump, whereby a separate return line to the fuel tank is avoided.

Out DE 195 40 549 A1 a combined injection and engine braking system for a multi-cylinder internal combustion engine is known. The injection and engine braking system has a plurality of valve assemblies, each of which is connected to another cylinder and in normal driving an injection unit and in braking operation, a hydraulic actuator on the respective cylinder is clock-connected to the pressure line.

A pressurized fluid feed system similar to the DE 41 26 640 A1 is from the DE 44 01 074 A1 is known and will be described below with reference to the 6 described in more detail:
6 shows a schematic section of the housing of the high pressure stage of the pressurized fluid supply system. The low pressure feed pump is designated by the reference numeral 10 designated. It is designed for example as a vane pump or roller-cell pump and can by an electric motor 11 are driven. The reference number 12 denotes a fuel tank of the motor vehicle, from which a low-pressure feed pump 10 Fuel, preferably gasoline or diesel fuel, sucks and this over a line 13 to a connecting piece 14 a high pressure pump 15 promotes, which is designed as a radial piston pump and directly to the internal combustion engine, that is arranged on the internal combustion engine and is driven by this.

The high-pressure pump has a plurality of equiangularly spaced star-shaped in a pump housing 20 arranged cylinders 21 with the central axes 22 , A central, pot-like interior 23 of the pump housing 20 is through a stopper 24 locked. In a hole 25 of the plug 24 and in one in the interior 23 opening blind hole 27 of the pump housing 20 is a pump shaft coupled to the internal combustion engine, not shown 28 at two spaced bearing sections 29 and 30 stored. Between the two bearing sections 29 and 30 points the pump shaft 28 one from the interior 23 recorded eccentric section 35 on, which is formed by a cylinder whose axis 36 around the eccentricity measure E to the axis 37 the pump shaft 28 is offset. On the eccentric section 35 is a lifting ring 39 rotatably mounted, the outside with a corresponding number of flats 40 is provided, all the same distance from the axis 36 of the eccentric 35 have, with equal angular distances over the outer surface of the cam ring 39 are distributed, and perpendicular to the individual cylinder axes 22 aligned and the cylinders concerned 21 assigned. With three at an angular distance of 120 ° star-shaped in the pump housing 20 arranged cylinders 21 Each adjacent flattening together form an angle of 60 °.

Every cylinder 21 has a central cylinder bore 41 with the axis 22 and takes in this exact fit a pump piston 42 on the inside over the cylinder 21 protrudes. At the protruding portion is on each pump piston 42 a sliding shoe 43 attached by a piston spring 44 which is between the sliding shoe 43 and an outer shoulder of the cylinder 21 is clamped against one of the flattenings 40 is pressed.

When the pump shaft 28 turns, retains the stroke ring 39 due to under the force of the piston springs 44 on the flats 40 resting sliding shoes 43 his orientation. Indeed revolves his axis 36 around the axis 37 the pump shaft 28 , The individual flattenings 40 are thus also moved on a circular path parallel to itself and thereby cause in interaction with the piston springs 44 a reciprocating motion of the individual pump pistons 42 in the cylinder bores 41 , The cam ring 39 opposite end face of a pump piston 42 limited a displacement 45 in the cylinder 21 , whose volume varies with the movement of the pump piston 42 changes. During a movement of the pump piston 42 radially inward and enlarged displacement 45 is thus sucked into this fuel. During the pressure stroke of the pump piston following this suction stroke 42 the fuel is displaced from the displacer under pressure.

To control these operations are for each cylinder 21 a suction valve 50 and a pressure valve 51 provided, both of which work in the manner of a check valve. The valve seats of the two valves 50 and 51 are for example on a single valve plate 52 formed between a cylinder 21 facing inside of a cylinder head 53 and the cylinder head 53 facing back of the cylinder 21 is trapped. The cylinder head 53 Holds the cylinder 21 in the pump housing 20 and with the latter is outside the cylinder 21 screwed.

To the suction valve 50 a cylinder 21 reaches fuel via a channel 54 in the corresponding cylinder head 53 and one in the area of the plug 24 in the interior 23 opening radial channel 55 of the pump housing 20 , Overall, one of the number of cylinders 21 corresponding number of channels 55 in the pump housing 20 available. In the same level as the channels 55 there is an annular groove 56 outside at the stopper 24 over which the channels 55 with a channel 57 of the housing 20 are connected, which radially into a bore 58 of the housing 20 flows from the outside radially into the interior 23 leads and into which the connecting piece 14 is used. About the pressure valve 51 will fuel over a canal 59 in every cylinder head 53 and a channel 60 in the case 20 , which has a central axial recess 61 in the pump housing 20 is connected, a pressure connection 62 fed by one of the three channels 60 emanates. In the central recess 61 is a pressure relief valve 63 used, which is electromagnetically adjustable and with the pressure in the connection 62 a certain pressure can be set. About the pressure relief valve 63 (DBE valve) flowing fuel passes through a to a nozzle 64 connected return line 65 to the fuel tank 12 back.

In order to ensure that a defect in the low-pressure feed pump or an injection nozzle consequential damage to the system itself or to the internal combustion engine can be largely avoided, is in the pressurized fluid supply system according to 6 arranged in the connection between the low pressure feed pump and the high pressure pump, a directional control valve, with which the connection can be shut off in the event of a defect. In detail serves - as from the 6 visible - the housing bore 58 between the connection piece 14 and one immediately at its mouth in the interior 23 seated support plate 70 as a valve bore of a directional control valve 71 and slidably takes as a control piston 75 trained valve member of the directional control valve 71 on. The pump housing 20 is therefore also the case of the directional control valve 71 , With this, the connection between the channel 57 of the pump housing 20 and the connecting piece 14 be shut off. This is between the spool 72 and the support plate 70 a helical compression spring 73 clamped the control piston 72 towards the hole in the hole 58 located end face of the connecting piece 14 loaded in the closing direction. In the opening direction of the directional control valve 71 acts on the control piston 72 the one in the line 13 and in the union 14 prevailing pressure, normally the feed pressure. The force of the helical compression spring 73 is relatively small, so that the control piston 72 by the feed pressure against the force of the helical compression spring 73 towards the support plate 70 to be moved. So if in the connection piece 14 Supply pressure prevails, so is the channel 57 for drilling 58 open. The directional valve 71 it is open. Below the pressure in the connection piece 14 However, a certain value, so pushes the helical compression spring 73 the control piston 72 against the connecting piece 14 , and the channel 57 is to the lead 13 shut off. The directional valve 71 is closed.

Out 6 is still apparent that the bore 58 and the support plate 70 in the area of the plug 24 extend through, so by the support plate 70 captive in the hole 58 is held.

Both the support plate 70 as well as the control piston 72 have a continuous axial bore 74 respectively. 75 in the control piston 72 a throttle point 76 having. From the connection piece 14 So can fuel through the throttle 76 in the interior 23 reach. Even if the helical compression spring 73 is compressed to block, the flow of the fuel is not obstructed, since the throttle point 76 and the axial bore 74 in the support plate 70 condition within the turns of the helical compression spring. The interior 23 is via a dashed housing bore 77 with the downstream side of the pressure relief valve 63 So with the return line 65 connected, so that when promoting low-pressure Spei sepumpe 10 a continuous flow of liquid through the interior 23 is maintained, and the pressure on the support plate 70 opposite side of the control piston 72 lower than the feed pressure. The sum of the spring force and the force generated by the lower pressure are smaller than those generated by the feed pressure and the control piston 72 Acting force.

That from the axial bore 76 outflowing fluid can - in accordance with the configuration of the pump assembly according to DE 41 26 640 A1 - Are also specifically carried out in an additional purge stream so that the mechanically and / or thermally particularly highly stressed areas of the high-pressure pump are included in the discharge flow path of the pre-funded excess pressure fluid. This then runs preferably in the axial direction from one side of the housing to the other end. There are thus preferably the bearings of the pump shaft, the eccentric section 35 , the bearing of the cam ring 39 as well as the flattenings 40 involved in a cooling flow at the bottom of the blind hole 27 is merged and from there via a radial channel 81 and a stitch channel 82 to a collection room 83 which leads over the neck 64 connected to the tank.

From the above description it follows that in normal operation, when the low-pressure feed pump delivers fuel, the directional control valve 71 is open. Fuel can over the channel 57 , the ring groove 56 and the channels 55 and 54 to the suction valves 50 the cylinder 21 reach. During the suction stroke of the pump piston 22 fuel flows into the enlarging displacement chambers 45 , During the compression stroke, the fuel passes through the pressure valve 51 into the channels 49 and 60 as well as in the recess 61 and the pressure connection 62 repressed. Fuel not required by the internal combustion engine flows via the pressure limiting valve 63 to the reservoir 12 back.

The delivery rate of the low-pressure feed pump is greater than the maximum delivery of the high-pressure pump, so that there is always an excess amount passing through the throttle point 76 of the control piston 72 of the directional valve 71 in the above-described cooling section and in the interior 23 flows and from there over the hole 77 and the line 65 also to the fuel tank 12 flowing back. It carries heat from the high-pressure pump 15 from.

If there is a defect in the low-pressure food pump 10 decreases the feed pressure, so that the directional control valve 71 closes and the channel 57 both to the low pressure feed pump 10 as well as to the interior 23 shut off. The high-pressure pump can only the part of the suction between the directional control valve 71 and the suction valves 50 leersaugen. Then the risk is low that from the actuated low-pressure feed pump 10 or from the interior 23 Solid particles in the cylinders 21 , to the pressure relief valve 63 or get to the injectors of the engine and damage these parts.

On the other hand z. For example, if an error is detected on an injection nozzle, the electric motor becomes 11 the low pressure feed pump 10 off. After the consequent drop in pressure in the connection piece 14 closes the directional valve 71 , so that in turn after a very short time the fuel supply to the engine is interrupted and greater damage can be avoided.

These known pressure fluid feed systems for common rail systems thus operate very reliable. However, sometimes there is the problem of excessive heating of the fuel. This in turn requires the use of more expensive Cooling systems, which are not only expensive, but the energy efficiency deteriorate the pump assembly.

Of the The invention is therefore based on the object, a pressurized fluid feed system of the type described above in such a way that with low, Device-technical effort of energy efficiency on is improved.

These The object is solved by the features of claim 1.

According to the invention by the throttling or by the cooling of the pump unit thermally loaded pressure fluid is no longer passed to the tank as before, but initially returned within the pump and immediately compressed again. This part of the medium thus no longer pollutes the heat balance in the tank, resulting in significant savings on the cooling system. The structure of the pump assembly, in particular the safety directional control valve according to DE 44 01 074 A1 or the cooling flow of the high pressure pump according to DE 41 26 640 A1 can be maintained largely unchanged and without functional impairment. Because the engine of the pump is further cooled by an oil flow, the higher input temperature of the compressed fluid to be compressed does not adversely affect the operation of the high pressure pump, in addition by appropriate shaping of the individual components of the high pressure pump can be ensured that a good heat dissipation or Heat radiation is given by the high-pressure pump. This results in the additional advantage that the recycled amount of thermally loaded pressure fluid simultaneously, for example, by skillful introduction into the Saugtrakt can be used to reduce the drive power of the low-pressure feed pump. This succeeds, for example, when the introduction of the recirculated pressure fluid similar to the principle of a jet pump, as z. B. in Zumischeinrichtungen find in fire extinguishing systems use. Another particular advantage is the fact that adjusts itself with the inventive redesign of the pressurized fluid supply system at the same time faster heating of the high pressure system, which is particularly at low outdoor temperatures at which the motor vehicle is operated, is of particular advantage. Finally, there is another advantage in terms of energy optimization of the system in that the temperature in the common high-pressure line (common rail) and thus the temperature of the leakage pressure fluid is higher than hitherto, so that when using a cooler in the drain line to the tank higher cooling efficiencies due to the larger temperature difference can be achieved.

Of the inventive structure The pressure fluid supply system is for different variants of the pressurized fluid supply applicable. So is to shut off the connection between the low pressure feed pump and the high-pressure stage be provided a directional control valve, with which the Operational safety of the system components in the event of malfunction of the low-pressure feed pump elevated becomes.

there will be the feed of the over the return line throttled pressure fluid and / or the outflowing cooling oil flow made via the directional control valve. The directional valve is thus transferred a double function, and it is ensured that at Shut down the directional control valve, the amount of pressurized fluid sucked by the high-pressure pump still be kept to a minimum.

The inventive design of the pressurized fluid supply system is for constant pressure high pressure pumps displacement equally applicable as for High pressure pumps with adjustable flow rate and suction throttle control. An advantageous Design of the pressurized fluid feed system using a high pressure pump with constant displacement is the subject of claim 2.

If the pressure relief valve is integrated into the pump housing, it is advantageous, the return line the pressure relief valve to lead directly over the directional control valve. at open directional control valve Thus, the throttled, thermally loaded fuel in the separate suction chamber downstream. the directional valve fed and the compression supplied by the high-pressure pump. It suffice for this purpose - as in claim 15 indicated, minor Constructional reconstruction measures at the directional control valve to ensure the double function of the valve.

It but it is also possible the pressure relief valve - accordingly Claim 4 - outside of the housing to install the pump set in the common high pressure line, and in this case, only the coolant flow from the pump unit via the To guide way valve. This has the advantage that on the pump no return connection required is. At the same time, the feed quantity from the low-pressure feed pump and thus their power consumption is reduced. The heat balance the fuel remains improved. Because according to this Variant the throttle volume of the pressure fluid from the pressure relief valve and the leakage of the injectors are summarized can surrender in the tank that flows to the tank Drain line higher Temperatures, reducing the cooling efficiency then possibly raised. Used in the drain line cooler can be. The cooling is more effective.

The directional control valve can still be equipped with comparable functions, as in the pump assembly according to DE 44 01 074 A1 the case is. Advantageous embodiments of the directional control valve are the subject matter of claims 5 to 14.

If the pump housing the high-pressure pump and the housing for the Directional valve is, so there is an immediate local Assignment between directional control valve and high-pressure pump. This can do that Volume of Speisetrakts the high-pressure pump, that of this the interruption of the connection to the low-pressure feed pump yet can be vacuumed, kept very small.

The Training according to claim 7 has the advantage that the Directional valve under the effect of the restoring force automatically assumes a blocking position when the feed pressure drops.

According to claim 10, the directional valve, with which the connection between the low pressure feed pump and the high pressure pump can be shut off, also used around the interior of the high pressure pump from the entrance to the displacement chamber shut off. So there is only one valve needed to interrupt the various connections.

It is also advantageous if the pressure in the interior of the high pressure pump is kept lower than the feed pressure, which is the subject of claim 12. In this way, a defined flow direction of the pressure fluid is present, and it is ensured that no possible with fixed Particles polluted fuel from the interior into the displacement of a pump piston passes. The pressure drop between the feed tract, between the low-pressure feed pump and the high-pressure pump and the interior can, for. B. be prepared by a throttle in the connection between the feed tract and the interior. Even with a check valve can be under utilization of its function as a pressure difference valve to generate a pressure drop between the feed tract and the interior. If such a pressure drop is present, so in the sense of a simple construction advantageously according to claim 12, the valve member of the directional control valve in the closing direction of the pressure in the interior acted upon. The higher feed pressure may still keep the directional control valve open. A separation of the space on the other side of the valve member from the interior and a separate connection to the return line is then not necessary.

If the high-pressure pump from a pump with adjustable delivery (Claim 17) is formed, it is preferably the feed of the thermally loaded excess pressure fluid upstream of the throttle valve, the throttle control of the flow rate is used. In this variant, a fuel cooler in each case omitted. At the same time, the oil flow decreases, from the fuel tank over a mostly existing fine filter are fed to the fuel pump must, considerably.

Around to keep the thermal stress of the pump is small, according to claim 18 preferably a flushing oil line branched off downstream of the throttle valve, which via a throttle to the pump unit guided is and their flushing oil after the Flow through of the pump set to the suction area of the low pressure feed pump is returned.

If the repatriation of the Flushing oil according to claim 19 done so that they is fed into the suction line of the low-pressure feed pump, so there is the particular advantage that no return line at all more is needed to the tank.

If the directional control valve according to claim 23 an emergency stop switch position has, then the required supply pressure for the pump can be reduced. For example, if a simple solenoid is used, the feed pressure is about halved.

Preferably the EMERGENCY STOP switch position is held by means of an electromagnet, the pressure of the force acting on the valve body low pressure counteracts.

below are schematic examples of several embodiments closer to the invention explained. Show it:

1 a schematic representation of a hydraulic circuit for implementing a first embodiment of the pressurized fluid supply system of the present invention;

2 in one of the 1 corresponding principle representation of the circuit of a second embodiment of the invention; and

3 to 5 Circuit diagrams to illustrate other embodiments of the invention, in which case high-pressure stages are used, which include a pump with adjustable flow rate and Saugdrosselsteuerung.

In the figures, those components which are the components of already described variants, such. B. the components of the pump assembly according to 6 correspond, provided with similar reference numerals, but preceded by the numbers "1" to "5".

The pressurized fluid feed system according to 1 , which for supplying a common high-pressure line 159 ie the common rail with a plurality of injectors 184 serves, has a low pressure feed pump 110 containing the fluid, ie fuel and in particular diesel fuel from a tank 112 sucks. For this purpose is a drive motor 111 provided in the form of a small electric motor. In the line 113 thus prevails when operating the low-pressure feed pump 110 a feed pressure of, for example, 1 bar overpressure, by a pressure relief valve 185 is adjustable. The supply of the suction line 155 the schematically indicated high-pressure pump 190 via a directional valve 171 , which is essentially the function of the directional control valve 71 the known pump arrangement according to 6 has, ie with sufficient delivery pressure in the line 113 is open and beyond a throttle point 176 and an axial bore 174 is capable of an interior 123 the high pressure pump 190 in a cooling oil flow with the supply line 186 and a drain line 187 included.

The operation of the high-pressure pump corresponds to that of the above with reference to the 6 described pump unit, ie it is a suction valve 150 and a pressure valve 151 provided over which the common rail 159 is fed. The high pressure feed line in the high pressure pump is with 159a designated. The housing of the high pressure pump 190 is indicated by a dotted line, so that it has a suction port AS and a high-pressure port AH. With dashed lines are the suction and pressure sides the other displacer of the high-pressure pump 190 indicated.

The pressure in the common rail 159 and thus the pressure in the high-pressure feed line 159a is controlled by the pressure relief valve (DBE) 163 adjusted, which is electromagnetically adjustable. In the embodiment shown, the DBE valve is located 163 within the dot-dash line 120 . 124 that the housing of the high pressure pump 190 suggests. The discharge line of the pressure relief valve 163 is with 188 designated. Leakage pressure fluid of the individual injectors 184 is via a common return line 189 to the tank 112 guided.

The peculiarity of the embodiment according to 1 is that the discharge line 188 the pressure relief valve or the DBE valve 163 not directly connected to the tank, but inside the pump housing 120 . 124 is recirculated so that it is in a separate suction downstream of the directional control valve 171 is initiated, that he immediately back from the high pressure pump 190 can be compressed. In other words, the discharge line 188 is via the directional control valve 171 with a feed connection 188a and a drain port 188b guided and behind the directional control valve 171 in the suction line 155 fed. That via the DBE valve 163 throttled pressure fluid, which is warmed up, ie thermally loaded, thus no longer burdened the heat balance in the tank 112 , Overheating of the engine or the drive unit of the pump 190 can be excluded, however, because the pump 190 continue over the lines 186 . 187 is cooled by an oil stream. Moreover, the traversed with the warmer fuel lots can be designed so that a good heat dissipation or heat radiation is given.

1 shows the position of a control piston 172 of the directional valve 171 in the closed state of the valve, ie in the event that the pressure in the feed line 113 is too low to the valve 171 to open. In this switching position is also the inlet connection 188a from the drain connection 188b separated. If the Niederduck feed pump 110 Fluid, ie fuel, is the control piston 172 against the force of a spring 173 according to 1 shifted upwards, causing the valve 171 is opened.

The control piston 172 has another control edge in the form of an annular recess 191 , which upon displacement of the control piston 172 according to 1 upwards in alignment with the connections 188a and 188b is brought so that it succeeds over the DBE valve 163 throttled heated fuel via the directional control valve 171 in the suction line 155 feed. In this case, by a suitable introduction of the discharge line 188 in the intake tract 155 the high pressure pump 190 the effect similar to a jet pump (see description of the jet pump or a water jet air pump in "Willi Bohl: technical fluid mechanics" in particular Figure 4.15) can be achieved, whereby it succeeds, the drive power of the low-pressure feed pump 110 to reduce. Because the directional valve 171 in the closed state also the discharge line 188 locks, is still in case of failure of the low-pressure feed pump 110 made sure that from the high pressure pump 190 circulated fluid has a minimal volume.

From the above description it follows that by the reintroduction of the heated, ie thermally loaded, throttled pressure fluid via the discharge line 188 a higher temperature of the pressure fluid in the common rail is achieved, and in less time, which proves to be advantageous for the operation of the injection system at low outside temperatures. With this higher temperature of the common rail, the temperature of the leakage fluid in the return flow line also increases 189 , If in this line thus a cooler 192 is installed, it can work with higher temperature differences and thus operated with a better thermal efficiency. The system is thus further optimized thermally.

Another variant of the pressurized fluid feed system is in 2 shown. This embodiment differs from the variant according to 1 in that a different type of recirculation of a partial flow of thermally loaded pressure fluid to the suction side of the high-pressure pump is selected. Specifically, here is the pressure relief valve 263 no longer in the pump housing 220 . 224 integrated, but in the common high pressure line, ie in the common rail 259 , On the other hand, recirculation takes place through the high-pressure pump 290 running cooling oil flow, ie the fluid in the drain line 287 that now optionally have a filter 287a to the connection 288a is guided. The directional valve 271 otherwise identical to the valve 171 the embodiment according to 1 educated. A special feature is that an emergency stop magnet 293 is provided, which allows the force of the biasing spring 273 to reduce so that the required supply pressure in the line 213 can be halved in about. The pressure relief valve 285 is modified accordingly, ie equipped with a different spring.

The over the pressure relief valve 263 throttled amount of pressurized fluid is the return line 289 upstream of a radiator 292 fed. Thus, the throttling amount of the DBE valve and the hot leakage amount of the injectors 284 upstream of the radiator 292 summarized, which again gives the possibility of more effective cooling.

Also in the embodiment according to 2 thus results in an improvement of the heat balance of the fuel. An additional advantage is that on the pump 190 no return connection is required. The power consumption of the pre-feed pump, ie the low-pressure feed pump 210 can by the recirculation of the cooling oil flow through the line 287 be kept smaller.

The invention has been described in pump assemblies with high pressure pumps 190 . 290 described with constant flow. However, it is clear that the principle according to the invention is not limited to such arrangements. In the following, embodiments are described which operate with high-pressure pumps whose flow rate is adjustable.

The high pressure pump 390 according to 3 is a throttle valve 394 upstream, so that the high pressure pump can be operated with a Saugdrossel control. The throttle valve 394 is designed for example as a continuously adjustable directional control valve, which is electrically adjustable against the force of a return spring. The supply of the high-pressure pump 390 done by a low pressure feed pump 310 , being between the low pressure feed pump 310 and the throttle valve 394 a filter 395 is provided.

For energy optimization or to reduce the thermal load of the tank system is in this variant, the hot leakage fluid of the injectors 384 via the return flow line 389 recirculated, ie in the feed line 313 upstream of the filter 395 fed. From the feeders 313 branches a flushing oil pipe 396 off, which has a throttle 397 to the pump unit of the high-pressure pump 390 is guided. The drain line 387 is to the tank 312 guided. It can be seen that a fuel cooler can be omitted here. The oil flow coming from the fuel tank 312 via a fine filter, not shown, to the low-pressure feed pump 310 must be promoted, is significantly reduced.

If the system according to 3 in the high pressure area to be secured by a pressure control valve, it is advantageous, the throttled flow rate of such a pressure control valve together with the leakage oil of the injectors 384 feed back into the low-pressure circuit. This is with the dashed lines in 3 indicated. The pressure control valve is with 398 denotes, and it can be seen that the discharge line 388 with the return line 389 is merged. The variant according to 4 differs from the embodiment according to 3 essentially only in that the drain line 487 for the flushing oil not to the tank 412 but to the suction line 499 the low pressure feed pump 410 is guided. This has the advantage that no return line to the tank 412 more is needed. Otherwise, the components of the embodiment according to 3 are used, the description of which is omitted here to avoid repetition.

The same applies to the embodiment according to 5 , that of the 3 also largely corresponds. Only the drive for the low-pressure feed pump 510 is varied. It is understood that the embodiments of the 4 and 5 also with a pressure control valve in the high pressure region of the pressure fluid feed system similar to the pressure control valve 389 the embodiment according to 3 can be equipped.

Of course they are Deviations from the previously described embodiments possible, without to leave the basic idea of the invention. While described at the embodiments either the return line the leakage and / or the pressure limiting device or from the Pump unit outflowing Cooling oil flow at least partially recirculated to the suction side of the high pressure pump downstream of the low pressure feed pump can, of course, be also take care be worn that both Fluid from the return line as well as the effluent from the pump unit cooling oil flow completely or at least partially returned to the suction side of the high-pressure pump.

The Invention thus provides a pressurized fluid supply system, in particular for the Supply of high-pressure manifolds (common rail systems), for example of injection systems for Internal combustion engines, one of which is a low pressure feed pump supplied high-pressure stage is provided. The excess pressure fluid quantity of the high pressure stage is by means of a leakage and / or pressure limiting device in a return line throttled. At the same time, the pump set is included in a cooling oil flow. to energetic optimization of the pressurized fluid feed system is the backflow and / or the flow of cooling oil flowing from the pump unit at least partially fed back into the suction side of the high pressure pump downstream of the low pressure feed pump. This results in a much lower heat load on the fuel system and at the same time a faster heating of the high pressure system at low outside temperatures.

Claims (25)

Pressure fluid feed system, in particular for the Supply of high pressure manifolds (common rail systems) such. B. of injection systems for internal combustion engines, with a supplied from a low-pressure feed pump high-pressure stage, the excess amount of pressurized fluid by means of a leakage and / or Druckfluidbegrenzungseinrichtung in a return line ( 188 ; 189 ; 288 ; 289 ; 388 ; 389 ; 489 ; 589 ) is throttled and their pump unit ( 190 ; 290 ; 390 ; 490 ; 590 ) in a cooling oil stream ( 186 ; 187 ; 286 ; 287 ; 396 ; 397 ; 387 ; 496 ; 497 ; 487 ; 596 ; 597 ; 587 ), wherein to shut off the connection between the low-pressure feed pump ( 110 ; 210 ; 310 ; 410 ; 510 ) and the high pressure stage ( 190 ; 290 ; 390 ; 490 ; 590 ) a directional control valve ( 171 ; 271 ; 394 ; 494 ; 595 ), characterized in that the return line ( 188 ; 189 ; 288 ; 289 ; 388 ; 389 ; 489 ; 589 ) and / or the pump unit ( 190 ; 290 ; 390 ; 490 ; 590 ) flowing cooling oil flow ( 287 ) at least partially into the suction side ( 155 ; 255 ; 355 ; 455 ; 555 ) of the high-pressure pump ( 190 ; 290 ; 390 ; 490 ; 590 ) downstream of the low pressure feed pump ( 110 ; 210 ; 310 ; 410 ; 510 ) can be fed and that the feed of the via the return line ( 188 ; 189 ; 288 ; 289 ) throttled pressure fluid and / or the outflowing cooling oil flow ( 287 ) via the directional control valve ( 171 ; 271 ) he follows ( 1 and 2 ) Pressure fluid feed system according to claim 1, characterized in that the high-pressure pump is a pump ( 190 ; 290 ) with constant displacement volume, and that in the high-pressure stage, a pressure relief valve (DBE) ( 163 ; 263 ) is provided, which is preferably infinitely and electrically adjustable and over which the excess amount of pressurized fluid can be throttled. Pressure fluid feed system according to claim 2, characterized in that the pressure relief valve ( 163 ) into the pump housing ( 120 ; 124 ) is integrated, and that the return line ( 188 ) via the directional control valve ( 171 ) is guided. ( 1 ). Pressure fluid feed system according to claim 2, characterized in that the pressure relief valve ( 263 ) outside the housing ( 220 ; 224 ) of the pump engine in the common high pressure line (common rail 259 ) and that of the pump engine ( 290 ) flowing coolant flow ( 287 ) via the directional control valve ( 271 ) is guided. ( 2 ). Pressure fluid feed system according to one of claims 1 to 4, characterized in that the directional control valve ( 171 ; 271 ) an adjustable valve member ( 172 ; 272 ) in a direction of a spring element ( 173 ; 273 ) is acted upon. Pressure fluid feed system according to claim 5, characterized in that the pump housing ( 120 ; 220 ) of the high-pressure pump and the housing for the directional control valve ( 171 ; 273 ). Pressure fluid feed system according to claim 5 or 6, characterized in that the directional control valve ( 171 ; 271 ) in a valve bore axially movable valve member ( 172 ; 272 ), which is acted upon by a restoring force in the opening direction from the feed pressure, Pressure fluid feed system according to claim 7, characterized in that of the low-pressure feed pump ( 110 ; 210 ) ago the inflow to the directional control valve ( 171 ; 271 ) axially in the valve bore and the valve member ( 172 ; 272 ) and that a suction channel ( 155 ; 255 ) of the high-pressure pump ( 190 ; 290 ) on the jacket of the valve bore emanating from this. Pressurized fluid feed system according to claim 8, characterized in that a connecting piece is inserted into the valve bore and that the connecting piece has at one end a stop for the valve member ( 172 ; 272 ) forms in the closing direction. Pressure fluid feed system according to one of claims 1 to 9, characterized in that the high-pressure pump ( 190 ; 290 ) a piston pump with at least one pump piston through which the volume of a displacement chamber is variable, and with a located in an interior lifting element, in particular a radial piston pump with at least one preferably internally rotatable on a rotatable driven eccentric shaft radial piston is that of the low pressure feed pump ( 110 ; 210 ) conveyed excess amount of fluid through the interior is derived and that the interior by a valve ( 171 ; 271 ) can be shut off to the entrance into the displacement. Pressure fluid feed system according to claim 10, characterized in that the interior space in front of the directional control valve ( 171 ; 271 ) to the connecting line ( 113 ; 155 ; 213 ; 255 ) between low-pressure feed pump ( 110 ; 210 ) and high pressure pump ( 190 ; 290 ) is connected and through the directional control valve ( 171 ; 271 ) can be shut off to the entrance to the displacement. Pressure fluid feed system according to claim 10 or 11, characterized in that means ( 176 ; 276 ) are provided to reduce the pressure in the interior compared to the feed pressure, and that the valve member ( 172 ; 272 ) of the directional valve ( 171 ; 271 ) can be acted upon in the closing direction by the pressure in the interior. Pressure fluid feed system according to claim 12, characterized in that the means for reducing the pressure in the interior by a throttle ( 176 ; 276 ) are formed. Pressurized fluid feed system according to one of claims 11 to 13, characterized in that the interior space through the valve member ( 172 ; 272 ) of the directional valve ( 171 ; 271 ) through to the connecting line ( 113 ; 155 ; 213 ; 255 ) between low-pressure feed pump ( 110 ; 210 ) and high pressure pump ( 190 ; 290 ) connected. Pressurized fluid feed system according to one of claims 7 to 13, characterized in that the valve member ( 172 ; 272 ) for the suction side of the high-pressure pump ( 190 ; 290 ) to be fed thermally loaded pressure fluid (DT) an additional control edge ( 191 ; 291 ), which together with the control edge for the feed pump ( 110 ; 210 ) coming pressure line ( 113 ; 213 ) is auf- and zuueruerbar. Pressure fluid feed system according to claim 15, characterized in that the additional control edge ( 191 ; 291 ) of a circumferential recess in the valve member ( 172 ; 272 ) is formed in the aufsteuernden state in overlap with a feed ( 188a ; 288a ) and a drain connection ( 188b ; 288b ) is for the thermally stressed pressure fluid. Pressure fluid feed system according to claim 1 or 10, characterized in that the high pressure pump ( 390 ; 490 ; 590 ) by a pump with adjustable flow, z. B. by an upstream suction throttle valve ( 394 ; 494 ; 594 ) is formed, and that the supply of the thermally loaded excess pressure fluid upstream of the throttle valve ( 394 ; 494 ; 594 ) he follows. Pressure fluid feed system according to claim 17, characterized in that upstream of the throttle valve ( 394 ; 494 ; 594 ) a flushing oil line ( 396 ; 496 ; 596 ), preferably before the supply of the thermally loaded excess pressurized fluid branches, which via a throttle ( 397 ; 497 ; 597 ) to the pump engine ( 390 ; 490 ; 590 ) is guided and their flushing oil after flowing through the pump engine, the suction area ( 312 ; 412 ; 499 ) of the low pressure feed pump ( 310 ; 410 ; 510 ) is returned. Pressure fluid feed system according to claim 18, characterized in that the flushing oil into the suction line ( 499 ) of the low pressure feed pump ( 410 ) is fed. Pressure fluid feed system according to one of claims 17 to 19, characterized in that the leakage fluid of the common high-pressure line ( 359 ) and / or the components supplied by it, such. B. the injectors ( 384 ) and the outflowing excess pressure fluid of a pressure valve ( 398 ) downstream of the high pressure pump ( 390 ) in a common return line ( 389 ) are summarized. Pressure fluid feed system according to claim 20, characterized in that the pressure valve is a pressure regulating valve ( 398 ) and preferably in the housing ( 320 ; 324 ) of the high-pressure pump ( 390 ) is integrated. Pressure fluid feed system according to one of claims 17 to 21, characterized in that the throttle valve ( 394 ; 494 ; 594 ) is a continuously adjustable directional control valve. Pressure fluid feed system according to one of claims 1 to 22, characterized in that the directional control valve ( 271 ) has an emergency stop switch position. Pressurized fluid feed system according to claim 23, characterized in that the EMERGENCY-OFF switching position by means of an electromagnet ( 293 ) is durable, the pressure of the on the valve body ( 272 ) counteracts acting low pressure. Pressurized fluid feed system according to one of Claims 1 to 24, characterized in that the recycled, thermally loaded fluid is conveyed via a filter device ( 287a ) is guided.

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