DE19706855A1 - Device for angular positioning of automotive camshaft with respect to cam wheel - Google Patents

Abstract

A camshaft (1) is linked to a drive wheel (2) which controls the opening and shutting timing of valves in an internal combustion engine. The shaft and wheel are linked by an adjustment unit (18) which is eccentric with respect to the shaft (1) axis (7). The adjustment unit (18) is a beam link connecting to two axles, the first axle being coupled with the shaft and the second being coupled with the drive wheel. The second axle 20 is located radial to the shaft and moveable in a circumferential direction.

Description

The invention relates to a device for angular adjustment a shaft, especially a camshaft, with respect to its type drive wheel, especially for phase shifting valve opening Opening and closing times for internal combustion engines, with the help one arranged in the power flow between the drive wheel and shaft Actuator.

To in an internal combustion engine with one or more cams wave the position of the timing relative to the piston movement - in terms of optimizing performance and consumption - change To make derbar is provided in DE-OS 19 47 362 in Camshaft drive the camshaft with increasing rotation to arrange the number of adjusting members that lag behind. The adjusting element is known as a centrifugal force adjustment limb trained.

EP 0 163 046 B1 describes a corresponding device for Angle adjustment of a shaft relative to a rotatable on the Shaft arranged drive wheel proposed hydraulic To provide funds. In the known, the wave should be at least one Have piston-cylinder pair. The position of each cylinder assigned piston determines the measure of the phase of the drive rads in relation to the shaft.

In a device for pha described in EP 0 607 509 B1  This is the displacement of the shaft relative to the drive wheel Measure of the adjustment also pre-selected by hydraulic means will give. In the known between a first Anla surface (on the shaft) and a second contact surface (on the An drive wheel) two directly in tight packing concentric adjacent rows of balls are provided. With help of a Piston should one row of balls axially into the other row of balls he can be pushed in by the arc distance between the he most and second contact surface to change. With functional one would have the ability with a small adjustment range (maximum equal to a ball diameter) one - of size depending on the adjustment path - adjustment angle of multiple Can reach greatness. When testing the well-known teaching but it turned out that the geome provided trie is practically excluded, in a row with one Large number of balls pressed against each other a second row of Push in balls of the same size because the two displacement forces acting on the balls occur in pairs cancel each other out.

The invention is based, for a device for angular adjustment of a shaft in relation to its drive wheel an arranged in the power flow between the drive wheel and shaft To create actuator, with the help of simple and space-saving design a sufficiently large angle adjustment is made possible. In a further embodiment, this is supposed to appropriate angle adjustment element with the help of a two-position Initiators, e.g. B. hydraulic piston, on the power flow between Drive wheel and shaft can be switched.

The solution according to the invention is that the Stell element arranged eccentrically with respect to the axis of the shaft is not. Some improvements and further refinements of the Invention are described in the subclaims.

Since the actuator in the power flow between the drive wheel and Wel le, a relay is sufficient when applying the invention  Active rotation or pivoting of the control element around the shafts axis to the desired angular position of the shaft relative to To reach the drive wheel. - It becomes with this consideration provided that the speed of the drive wheel in fixed loading drawing to the speed of the crankshaft of the machine. The The angular position or phase of the camshaft is changed so relative to the drive wheel. The term shaft and drive wheel is also used for on the shaft or on the drive wheel brought flanges used. The terms radial, axial and in Unless otherwise stated, the circumferential direction refers is basically on the shaft axis or drive wheel axis.

According to another invention is used as an (eccentric) control element preferably a rocker connecting two pivot axes is preferred see, the one, first pivot axis of the rocker with the Shaft and the other, second pivot axis with the drive wheel only radially displaceable with respect to the shaft axis is coupled. The second swing axis of the swing arm is there at the same time radially and circumferentially with respect to the Axis of the shaft movably supported on the shaft.

If you apply a force in the direction of rotation to such a swing arm the engine, e.g. B. by a circumferential (in relation to the wel lenachse centric) cam, is exercised (with a Rotation through 360 °) the only radially movable, first swivel axis the rocker once radially back and forth with respect to the shaft axis forth and the other, second pivot axis of the rocker becomes a guided around on an ellipse line. This corresponds to the one ellipse axis of the radial movement of the first Swing axis of the swing arm and the other ellipse axis there the measure of the angular adjustment to be achieved according to the invention in front. The first pivot axis of the rocker should, preferably in Shape of a pin or the like driver, movable in a radial slot of the shaft (shaft slot) who stored the while the second pivot axis - also preferred in Shape of a pin - movable in a radial slot of the Drive wheel (drive wheel slot) should engage.  

Spatially around the elliptical movement of the second pivot axis enable, is preferably in one to the rocker adjacent shaft part, especially on a shaft flange, a window (wave window) is provided, the dimensions of which are in Rich radius and circumference for the elliptical orbit are sufficient. The radial and circumferential at the same time (with respect to the shaft) movable, second pivot axis of the Swing arm can then through the window into the radial slot of the drive wheel.

The control element according to the invention can according to the invention be formed in one or more parts in different ways. An actuating element is preferred which has the shape of a one-piece gene (in particular semicircular or fully circular) semi- or Full ring. If necessary, the half ring should be on NEN longitudinal ends or the full ring at about diametrically opposite lying points each form one of the swivel axes the pin for engagement in the respective slot of the shaft or drive wheel.

Such a circle half-ring or full circle should be according to white teren invention in an eccentric circular groove in relation cam mounted centrally on the shaft - slidable in the groove circumferential direction - to be positioned. The Cam then forms a directly on the actuator acting actuating means, e.g. B. for pivoting the swing arm connecting both swivel axes. If the swingarm with its first pivot axis in the radial shaft slot and with the second swivel axis - through the wave window - engages in the radial drive wheel slot and when the Swing cam in its eccentric groove is rotated around the shaft or drive wheel axis both pivot axes in their radial slot only in radial direction that in the slot of the drive wheel but gripping second pivot axis also leads to the world lenfenster a movement in the circumferential direction relative to the shaft  tung from. This movement in the circumferential direction causes it angular adjustment of the shaft in accordance with the invention their drive wheel.

Since it is relative movements above, the Slots and windows can also be exchanged kinematically, that means for example the window can alternatively also in the Drive wheel or provided in a flange of the drive wheel be so that the corresponding pin through this window engages in a radial slot of the shaft. In a ver the camshaft is basically the engine with the hal ben speed of rotation of the crankshaft. This drive Should generally not be by the means according to the invention be impaired. The result is that for each because the phase shift desired by angular adjustment Camshaft currently braked against the drive wheel or should be accelerated.

Since the control element according to the invention during normal operation of the The machine rotates with the number of revolutions of the drive wheel unbalance problems occur without countermeasures. For one The aforementioned can be balanced or evenly distributed Cam that the actuator in the eccentric groove records, be advantageous. A practically exact comparison Division of mass (with respect to the axis) is achieved if the control element is circular and the eccentric circular groove essentially like that taken for making the groove Fills the mass so that the cam comes into question the rotational speed appears exactly balanced. That will be with achieved, for example, when the cam and the actuator element of about the same material if the groove has an approximately rectangular cross section and if the Cross section of the control element is also rectangular and as large is that the desired pivotal movement of the actuator in the groove is just still possible.

According to another invention, this can be done in the eccentric circle  only mounted actuator from two or more individual parts, in particular from a large number of individual balls or rollers, consist. The roller axes should then be perpendicular to the the circular groove spanned plane or parallel to the shaft axis stand. If necessary, for example, two of the individual parts (preferably rollers) protrude from the circular groove in such a way that they have the pivot axes described above and thus in engaging the radial slots of the drive wheel and shaft Form cones.

As a further alternative, who can be provided according to the invention with an eccentric groove for receiving the control element deviating from the circle in a (again) with respect to the shaft has a centrally mounted cam see and the actuator from a variety of - just like before - in the groove guided individual parts, especially Ku gels or roles. One of those Circular deviating groove can be formed when the Stellele benefits from a multitude of individual parts, if a special (e.g. non-linear dependency on Swivel angle of the cam disc and the angle adjuster reached tion of the shaft in relation to the drive wheel is desired.

During normal operation of the respective shaft, the drive wheel, the control element - with the cam if necessary - and the shaft is so tightly coupled to each other that it is exactly same speed - the speed of the drive wheel - rotate. This fixed coupling is used for an angular adjustment to the posi tive or negative phase shift of the shaft rotation right solved briefly relative to the drive wheel rotation.

In a preferred exemplary embodiment, a switchable planetary gear set dependent on the motor drive Ring gear and driving wheel (center wheel) are provided if at In normal operation the drive wheel runs loose with the drive wheel. A cam disc that contains the control element can be coupled to the shaft. For the angle adjustment who  the then - preferably by an unspecified piston stroke Min minimum size (two-position piston) at the same time the fixed size (none Relative rotation) coupling of cam and wel le solved and the drive wheel synchronized with the shaft. The drive wheel takes this during synchronization Ring gear with. If this is then coupled to the cam disc the ring gear rotates as there are fewer teeth than the driving gear has, the cam by a predetermined angle relative to the drive wheel. As a result of this filming the Cam disc that is possibly eccentrically posi in it tioned actuator by a predetermined amount pivots such that the actuator with the help of his Swivel axes or pins the right angle adjustment of the shaft caused relative to the drive wheel.

A major advantage of this - described in more detail below NEN - adjusting device is that the Synchronisie tion of the drive wheel with the shaft and loosening the fixed Coupling of shaft and cam with a suitable design tion with an extraordinarily small, e.g. B. include only mm the, actuation stroke of only two positions (yes-no) piston are possible. For the measure of the relative adjuster lung is not an accurately sized one difficult controllable (e.g. hydraulic) actuation stroke of the piston, but rather the time during which the driving wheel is with the shaft is synchronized and the shaft and cam are not are coupled.

To activate or switch on the effect (angle adjustment) the actuator according to the invention also come with other drives be, for example a drive via a hydraulic element, such as Cylinders, rotary lobes, etc. in question. The direction of rotation of the tax The element can be constant, but the direction of rotation can also be designed reversing.

Based on the schematic representation of exemplary embodiments some details of the invention are explained. Show it:

Figure 1 is a vertical section through an inventive device for angular adjustment of a camshaft relative to its drive wheel.

Fig. 2 is a section along the line II-II of Fig. 1;

Fig. 3 is a schematic representation of a Stellele element in two positions;

. Fig. 4 is a comparison of Figure 1 is modified design of the cam disc with adjusting element containing coupling between the drive wheel and shaft;

Figure 5 shows a further modification of the cam with the actuator containing clutch between the drive wheel and shaft. and

FIGS. 6 and 7 show two different forms of a gene not kreisförmi groove for ball or roller rows as actuating element a cam.

In Figs. 1 and 2, an embodiment of a device for angular adjustment of a shaft 1 (in particular camshaft) is described relative to its drive wheel 2. The drive wheel 2 can have, for example, a toothed ring 3 on the circumference, which is driven in a conventional manner by the crankshaft of the machine in question via a chain (not shown). A shaft flange 4 is permanently connected to the shaft 1 . With the shaft flange 4 , a piston 5 - with the help of an (axial) tongue and groove connection 6 , which is displaceable in the direction of the shaft axis 7 - so connected that the piston 5 follows each rotation of the shaft 1 exactly. The shaft 1 is in a housing 8 , for. B. on the cylinder head. In the same as the housing 8 fixed motor part 9 is a pressure medium supply 10 , by means of which the piston 5 in the direction of movement 11 against the restoring force of a spring 12 can be switched back and forth.

In the exemplary embodiment according to FIG. 1, the piston 5 has two coupling surfaces 13 and 14 , which can optionally be coupled to adjacent components, namely on the one hand with the drive wheel 15 of a planetary gear set with ring gear 16 and which can be engaged or engaged in the power flow between drive wheel 2 and shaft 1 on the other hand with the cam disc 17 , which receives a control element 18 according to the invention ( FIG. 2) with pivot axes or pins 19 and 20 . The pin 19 is guided in a radial slot 21 of the shaft flange 4 . The pin 20 is guided in a radial slot 22 of the drive wheel 2 . In the exemplary embodiment according to FIGS. 1 and 2, the adjusting element 13 is located in a circular groove 23 which runs eccentrically with respect to the center of the cam disk 17 . The center point of the cam disk 17 lies in the shaft axis 7 .

The adjusting element 18 according to FIG. 2 can preferably be designed or referred to as a rocker. For an explanation of the rocker movement, reference is also made to FIG. 3. There, on the cam 17, two extreme positions 18 a and 18 b of the actuating element 18 are shown in principle. Accordingly, the extreme positions of the pin 19 with 19 a and 19 b are designated as those of the pin 20 with 20 a and 20 b. While the pin 19 moves when the cam 17 rotates on the radial straight line 24 , the pin 20 is moved along an elliptical line 25 . In order to make room for this, a window F is provided in the shaft flange 4 ( FIG. 2). In general, only the direction of rotation 26 of the motor is suitable for the rotation of the cam disk 17 . If the pin 20 moves from the position 20 a to the position 20 b, since the pin 20 is supported in the slot 22 of the drive wheel 2 , which may be permanently driven, the shaft 1 with the aid of the pin 19 which is in the shaft slot 21 intervenes to the Win wel pivoted relative to the drive wheel 2 . The length of the straight lines 24 and the dimension of the angle w determine the minimum size of the window F in the direction of radius or circumference.

During normal operation of the device according to the invention, the shaft 1 is non-rotatably coupled to the drive wheel 2 . This fixed coupling provide the pin 19 and 20 of the actuating element 18 , which is arranged in the frictional connection between the shaft 1 and drive wheel 2 . A prerequisite for this is a connection on the coupling surface 14 between the piston 5 and the cam disk 17 .

If an angular adjustment of the shaft 1 relative to the drive wheel 2 is desired, ei ne force in the direction of movement 11 is exerted on the piston 5 via the pressure medium supply 10 , so that it is uncoupled from the cam disk 17 on the coupling surface 13 and (practically at the same time) on the Coupling surface 13 is switched to the drive wheel 15 . As a result, the drive wheel 15 is synchronized with the piston 5 and thus with the shaft 1 . At the same time, the drive wheel 15 constantly meshes with the teeth of the ring gear 16 . This is e.g. B. connected via a radial groove and Fe derverbindung with the cam 17th The cam disc 17 can (in the exemplary embodiment on the circumference 27 ) rotate freely with respect to the drive wheel 2 . Since the drive wheel 15 has fewer teeth than the ring gear 16 , it has a correspondingly larger number of revolutions. When synchronizing the driving wheel 15 with the shaft 1 , this is currently rotated faster than the drive wheel 2 . This relative rotation causes a rotation of the cam disk 17 and thus a pivoting of the actuating element 18 and in turn thereby a change in the phase of the shaft 1 with respect to that of the drive wheel 2 . The relative rotation is continued until the degree of the desired phase shift is reached.

In the exemplary embodiment, a sensor 28 is provided for measuring the result or for switching off the synchronization of drive wheel 15 and shaft 1 , which detects the position of the pin 20 and switches off the pressure medium flow at the feed 10 at the given time, so that the spring 12 two-position piston 5 brings back to its original position in which the drive wheel 15 runs loose and the clutch face 14 of the Kol ben 5 connects with the cam 17th

FIG. 4 shows some components that have been modified compared to FIG. 1. All other components of FIG. 1 can be adopted unchanged in the embodiment of FIG. 4. The WE sentliche difference between FIG. 1 and FIG. 4, represents in that, between the cam 17 and the drive wheel 2, a brake element 29, and constantly ensures between cam 17 and shaft flange 4 a brake member 30 for driving contact. This contact is sufficient for normal operation, but is interrupted by force, while the piston 5 is synchronized with the drive wheel 15 by its movement in the direction 11 . Everything else then works as described with reference to FIGS. 1 and 2 ben.

Fig. 5 shows a further embodiment with a change compared to Fig. 1. Only the parts changed compared to Fig. 1 are shown in Fig. 5. In the exemplary embodiment according to FIG. 5, the driving wheel 15 is constantly synchronized with a coupling 31 or the like with the shaft flange 4 and thus with the shaft 1 . Without further ado, it would drive the connection to the cam 17 as previously connected via a radial groove-Fe derverbindung 32 ring gear 16 and the cam 17 (constantly) and thus constantly change the angle between shaft 1 and drive wheel 2 . However, is adjustment This permanent angle of FIG. 5 is normally prevented for this purpose is guided in normal operation through the supply line 10 the pressure medium in the direction of the piston 5 ', so that it is coupled to the coupling surface 33 with the ring gear 16 of. As a result, the piston 5 ', the ring gear 16 and the drive wheel 15 rotate at the same speed and thus also at the speed of the shaft 1 , which is - because of the actuating element 18 with pin 19 and pin 20 switched into the power flow - the speed of the Drive wheel 2 . The other parts of the exemplary embodiment according to FIG. 5 correspond to those according to FIG. 1.

FIGS. 6 and 7 show two embodiments of an adjustment element 18 formed as a ball or roller row '. In both cases, the grooves 34 and 35 provided in the cam disk 17 have a circumference that deviates from the circular shape. In Fig. 6, one can e.g. B. speak of an egg shape, in Fig. 7 of a heart shape. The eccentricity of the groove 34 , 35 in FIGS. 6 and 7 is determined not only by the position but also by the shape of the rods 34 and 35 . In the drawings shown, the elements shown at the end of the ball or roller row 18 'are drawn dark to show that this can be the pin 19 , 20 corresponding elements.

There is a device for angular adjustment of a shaft GE compared to their drive wheel with the help of a force flow between the drive wheel and shaft arranged actuator be written. The actuator is to allow for simple and space-saving design an angular adjustment in a large Winkelbe rich, without the need for specially controlled means to drive. According to the invention - as drawn in FIGS. 1, 2, 4 and / or 5 - an actuating element is arranged eccentrically with respect to the axis of the shaft. It should preferably be designed as a swing arm comprising two pivot axes.

Reference list

1

wave

2nd

drive wheel

3rd

Sprocket

4th

Shaft flange

5

piston

6

Tongue and groove connection (axial)

7

Shaft axis

8th

casing

9

Engine part

10th

Pressure medium supply

11

Direction of movement

12th

feather

13

Coupling surface (

17th

)

14

Coupling surface (

15

)

15

Driving wheel

16

Ring gear

17th

Cam

18th

Actuator

19th

,

20th

Pins, swivel axes

21

radial slot (

4th

)

22

radial slot (

2nd

)

23

Circular groove

24th

Straight

25th

ellipse

26

Direction of rotation

27

Scope (

17th

)

28

sensor

29

,

30th

Braking element

31

Dome toothing

32

Tongue and groove connection (radial)

33

Coupling surface

34

Groove (

Fig.

6)

35

Groove (

Fig.

7)
F window
w angle

Claims (17)

1. Device for angular adjustment of a shaft ( 1 ) with respect to its drive wheel ( 2 ) with the aid of an adjusting element ( 18 ) arranged in the power flow between the drive wheel ( 2 ) and shaft ( 1 ), characterized in that the adjusting element ( 18 ) is eccentric with respect to the axis ( 7 ) of the shaft ( 1 ) is arranged. 2. Device according to claim 1, characterized in that a rocker connecting two pivot axes ( 18 , 19 ) is provided as the adjusting element ( 18 ), the one, first pivot axis with the shaft ( 1 ) and the other, second pivot axis with the drive wheel ( 2 ) each - with respect to the shaft axis ( 7 ) - is coupled only radially. 3. Apparatus according to claim 2, characterized in that the second pivot axis ( 20 ) of the actuating element ( 18 ) is mounted to the same radially and in the circumferential direction of the shaft ( 1 ) movable to this. 4. Apparatus according to claim 2 or 3, characterized in that - each in the form of a pin or the like - he ste pivot axis ( 19 ) of the actuating element ( 18 ) movable in egg nen radial slot ( 21 ) of the shaft ( 1 ) and second pivot axis ( 20 ) movably engage in a radial slot ( 22 ) of the drive wheel ( 2 ). 5. The device according to at least one of claims 2 to 4, characterized in that the at the same time radially and circumferentially movable, second pivot axis ( 20 ) of the actuating element ( 18 ) is mounted so that it with a complete radial back and forth movement ( 24 ) of the other pivot axis ( 19 ) of the actuating element ( 18 ) approximately circumscribes an ellipse ( 25 ). 6. The device according to at least one of claims 2 to 5, characterized in that the simultaneously radially and circumferentially movable, second pivot axis ( 20 ) of the actuating element ( 18 ) through an adjacent shaft part ( 4 ) provided window (F) in the slot ( 22 ) of the drive wheel ( 2 ) engages. 7. The device according to at least one of claims 2 to 6, characterized in that the adjusting element ( 18 ) has the shape of a one-piece half or full ring. 8. The device according to claim 7, characterized in that the half ring at its longitudinal ends or the full ring at diametrically opposite points each one of the pivot axes forming pin ( 19 , 20 ) or the like for engagement in the slot ( 21 ) of the shaft ( 1st ) or in the slot ( 22 ) of the drive wheel ( 2 ). 9. The device according to at least one of claims 7 or 8, characterized in that for receiving the half or full ring ( 18 ) an eccentric circular groove ( 23 ) on a total with respect to the shaft ( 1 ) together centrally mounted cam ( 17th ) is provided. 10. The device according to claim 9, characterized in that the cam ( 17 ) with groove ( 23 ) and therein the actuating element ( 18 ) is balanced overall for trouble-free concentricity. 11. The device according to at least one of claims 1 to 10, characterized in that for receiving the actuating element ( 18 ) an eccentric circular groove ( 23 ) in a generally centric and relative to the actuating element ( 18 ) on the shaft axis ( 7 ) rotatably mounted cam ( 17 ) it is provided that the actuating element ( 18 ) at diametrically opposite points each has an axially jumping pin or similar driver ( 19 , 20 ) be that the one, the first pin ( 19 ) in a radial shaft slot ( 21 ) one with the shaft ( 1 ) connected shaft flange ( 4 ) protrudes radially so that the shaft flange ( 4 ) approximately diametrically opposite the shaft slot ( 21 ) has a window (F) whose radial extension is at least approximately equal to the radial shaft slot length and its extension in the circumferential direction (with respect to the shaft axis 7 ) is at least equal to an intended minimum Winkelver, and that the second Za Plfen ( 20 ) in the region axially adjacent to the window (F) into a radial slot ( 22 ) of a drive flange connected to the drive wheel ( 2 ) - radially displaceable with respect to the shaft axis ( 7 ) or drive wheel axis. 12. The device according to at least one of claims 9 to 11, characterized in that the Stellele element ( 18 ) mounted in the eccentric circular groove ( 23 ) consists of two or more individual parts. 13. The apparatus according to claim 12, characterized in that the actuating element ( 18 ) consists of individual balls or rollers ( 18 '). 14. The device according to at least one of claims 1 to 13, characterized in that for receiving the actuating element ( 18 ) has an eccentric groove ( 34 , 35 ) with a shape deviating from the circle in an overall centrally mounted cam with respect to the shaft ( 1 ) ( 17 ) is provided and that the adjusting element ( 18 ') consists of a plurality of individual parts guided in the groove ( 34 , 35 ), in particular balls or rollers ( FIGS. 6 and 7). 15. The device according to at least one of claims 1 to 14, characterized in that the window (F) is assigned a sensor ( 28 ) for determining the position of the second pin ( 20 ). 16. The device according to at least one of claims 1 to 15, characterized in that the cam ( 17 ) for the exact setting of the Win angle or the phase between the drive wheel ( 2 ) and shaft ( 1 ) on the shaft drive or motor drive is switchable . 17. The apparatus according to claim 16, characterized in that a planetary gear set ( 15 , 16 ) which can be latched into the power flow between the drive wheel ( 2 ) and shaft ( 1 ) is provided as the motor drive-dependent drive of the cam disc ( 17 ) (FIGS . 1, 4 , 5)