JP2000145908A - Continuously controllable wrapping transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To freely increase the pressure bonding force of a conical disc to a wrapping member, continuously control a wrapping transmission, device and decrease the number of structural members to reduce the cost by constructing a discharge conduit opened to a pressure medium reservoir and/or the pressure medium reservoir to be loaded by back pressure. SOLUTION: A conical disc pair 1 of the input side A and a conical disc pair 2 of the output side B are respectively provided with axially movable disc parts 1a, 2a and axially immovable disc parts 1b, 2b, and a wrapping member 3 is wrapped between both disc pairs 1, 2. To vary the effective diameter of each disc pair 1, 2, control members including cylinder units 4, 5 are provided, and cylinder units 6, 7 are provided operationally in parallel to the cylinder units 4, 5. Pressure load or pressure release to the pressure chambers 6a, 7a of the cylinder units 6, 7 by a reservoir are performed through a control valve 10 formed by fitting a slider 44 to a valve casing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a continuously adjustable winding transmission, in particular a winding transmission for motor vehicles, which is connected on the input side to a drive element and on the output side at least one drive gear. A pair of conical disks, each connected to a drive shaft for the purpose of mounting an endless winding member for drivingly connecting the two conical disk pairs,
At least one hydraulic adjusting member is axially movable and at least one hydraulic adjusting element is used to adjust the transmission ratio and / or the transmission of the moment. Of a type intended to be loaded.

[0002]

2. Description of the Related Art Such a wrapping transmission is already known from DE-A.
OS 19544644, DE-OS 19546
No. 293 and DE-OS 19546294. Each of these three configurations has a so-called torque feeler arranged in a force transmission path between the drive member and the pair of conical disks on the input side. The torque feeler controls the conical disk pressing force or the pressing moment to tension the wrapping member in relation to the rotational moment and the transmission ratio to be transmitted.
In this case, a suitable adjusting element is loaded with a pressure medium provided by a pressure supply for this purpose in order to axially load the winding means.

When such a transmission is loaded from the output side at the peak moment of rotation, for example by a block of gears or the like, a clutch arranged in particular between the first pair of discs and the drive unit Are not fully engaged and the required rotational moment cannot be transmitted,
It is possible that the winding member slides on the conical disk.

[0004]

The object of the present invention is to provide a continuously adjustable winding transmission which can increase the pressing force or the pressing moment of the conical disk against the winding member in appropriate circumstances. It is another object of the present invention to provide an apparatus which requires a minimum amount of additional components and can be manufactured cost-effectively.

[0005]

SUMMARY OF THE INVENTION An object of the invention is to provide a pair of conical disks, each coupled to a drive member on one input side and coupled to a drive shaft for at least one drive gear on the output side. The problem is solved by a continuously adjustable winding transmission which is provided for tensioning an endless winding means for drivingly connecting the two conical disk pairs. In this case, at least one conical disk of a pair of conical disks can be moved axially, and in each case at least one hydraulic adjusting element is used to adjust the transmission ratio and / or the transmission of moment. It can be loaded with pressure by supplying a medium. In this case, the pressure is regulated by a control valve arranged between the pressure supply device and the adjusting member, and a discharge conduit is provided for a pressure medium that is not required, which opens into a pressure medium reservoir. The discharge conduit and / or the pressure medium reservoir can be loaded with back pressure.

[0006] Such a continuously adjustable winding transmission is preferably designed in such a way that two adjusting members are provided for each conical disk pair. In this case, in each case one adjusting element supplies mainly pressure for transmitting the moment, and in each case one adjusting element supplies pressure for adjusting the transmission ratio. The control valve is then controlled to adjust the transmission ratio. This is particularly advantageous when it is desired to react the wrapping transmission quickly and when the wrapping transmission has a high crimping force. The two adjusting members that effect the crimping of the wrapping member can be connected to one another such that both adjusting members exert substantially the same crimping force on the wrapping member. In this case, the adjusting member for adjusting the transmission ratio can be designed small, and the transmission ratio can be changed more quickly. For this purpose, the adjusting element for providing the crimping force and the adjusting element for providing the transmission ratio are advantageously supplied with a pressure medium by means of a pressure medium supply, for example a pump.

[0007] The pressure medium is supplied as a differential pressure by a control valve which can advantageously be configured as a differential pressure valve. Excess pressure medium is led from the control valve via a discharge line to a pressureless tank or to a pressure medium reservoir. In this case, a control, for example a pressure limiting valve, is preferably arranged between the outlet of the control valve and the discharge line, so that a blocking pressure is generated when the excess pressure medium is withdrawn. This damping pressure causes an increase in pressure in the supply passage from the outlet side of the control valve and thus in the adjusting member which loads the axially movable cone.

[0008] It is further advantageous that the pressure limiting valve is configured to be adjustable so that a constant pressure can be pre-selected or the valve can be adjusted or controlled so that the control unit can operate the pressure limiting valve in advance. The goal is to provide a selected or controlled pressure.

According to another inventive concept, one embodiment is
It can be provided that the pressure loading at the outlet of the control valve takes place at a pressure prepared for supplying pressure medium to the proportional valve. For example, the supply pressure of an arbitrary proportional valve provided in the winding transmission can be involved. In this case, the supply line can be connected to the discharge line of the control valve. The supply line of the proportional valve, which advantageously controls the control valve, can be involved in the pressure rise. This allows the discharge conduit or outlet of the control valve to be at a constant pressure, for example 3-8 × 1
0 ⁵ Pa in can be loaded, whereby it is possible to increase regardless of the operating condition of the pressing force as well.

Another possibility of increasing the pressure at the outlet of the control valve is to do this with a damping pressure generated in the suction jet pump. In this case, the blocking pressure can be independent of the predetermined operating state of the winding transmission. For example, a suction jet pump can be operated when the clutch arranged between the drive unit and the input-side pair of conical disks slips or rubs, so that a damping pressure can be built up. This is advantageous because, under appropriate operating conditions, for example when starting or braking on grounds of different adhesion, a sudden torque peak occurs.

[0011] A further advantage is that any combination of the above-mentioned possibilities for increasing the pressure is possible. The rise in pressure at the outlet of the control valve is therefore effected either by connection to a pressure supply line for the proportional valve or via a pressure limiting valve in the discharge line of the control valve and the rise in pressure in the event of a torque peak occurs. To this end, additional pressure can also be created by connecting the suction jet pump with a damping pressure conduit.

Alternatively, the back pressure can be predetermined by the control unit by additionally or selectively calculating or inferring an adjustment value in connection with the at least one operating parameter. In this case, the operating parameters can be sensor signals, which are generated from sensors which detect non-constant wheel rotations or wheel blocks and are appropriately prepared, for example, in corresponding driving conditions, for example, on different ground When the vehicle suddenly generates a rotational moment peak when the vehicle is driven on the vehicle, the pressure can be increased in the conical disk that can move in the axial direction.

Furthermore, another operating parameter can be a regulation value or a signal from another control unit, which can be, for example, an anti-block or anti-slip regulation system or a system for regulating the driving characteristics. In this case, the signal is faster than a moment feeler mechanically arranged in the transmission path between the set of conical disks and the drive unit, especially if the clutch does not transmit the required rotational moment or none at all. Given, and thus can react more quickly to rotational moment peaks.

According to another inventive concept, the pressure on the discharge line of the control valve is effected by means of a valve which controls the flow in the discharge line in relation to the rotational moment impact occurring on the output drive shaft. be able to. For this purpose, a chamber for forming an axially displaceable rotary mass and a valve volume, which is arranged on the drive shaft in a restricted and rotatable manner, is provided with a discharge conduit to the pressure reservoir and a control valve. An arrangement consisting of a supply conduit can be used. In this case, the rotary mass controls the conduit cross section of the conduit between the control valve and the pressure medium reservoir with axial movement upon a rotational moment impact.
Advantageously, the rotary mass is rotatable with the drive shaft in a mutually restricted manner by means of a screw, so that in the case of rapid changes in the rotational speed of the output drive shaft, the rotary mass is mounted rotatably on the drive shaft. Due to the mass, a relative rotation of the two parts takes place, so that an axial movement of the rotating mass takes place by means of a rotation along a thread, which can also be designed only in the form of a ramp. This axial movement is likewise used to reduce the cross-section of the conduit between the control valve and the pressure medium reservoir, for example, to increase the pressure in the set of conical disks by closing and effecting a dam. Can be.

In this case, it is advantageous for the rotary mass to be pivoted against the effective return action of the energy storage device in the axial direction in the event of a rotational moment impact. This energy accumulator returns the rotary mass to the starting position again after a rotational moment impact, and thus reverses again the rise in the crimping moment of the conical disk. For this purpose, the energy storage device can be configured, for example, as a coil spring, a disk spring or a diaphragm spring, and can be configured to act in a compression direction or a tension direction depending on the arrangement.

[0016] Advantageously, the chamber in which the supply conduit opens and the control process of narrowing or closing the conduit takes place is formed by the rotating mass and the drive shaft. In this case, both parts are sealed tightly to one another at the required pressure. In a further preferred embodiment, a fixed casing part, for example a part of the transmission casing, can form a chamber. In this case, the supply can take place via this housing part, so that the supply which pivots on the conduit can be stopped.

If, of course, one supply of the conduit is provided by a rotating mass and the other supply of the conduit is provided by an output drive shaft, the action of narrowing or closing the conduit can also take place without axial movement. . In this case, the openings face each other and are pivoted relative to one another, for example by means of at least one circumferentially acting energy storage device, in relation to a rotational moment impact whose magnitude is predetermined by the size of the energy storage device, and thus the conduit. The position is fixed so as to determine the flow through. When normal operation is achieved without a torque peak on the output side, the energy storage device separates the openings again. The openings can be provided as advantageously configured control edges.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wrapping transmission or a conical-disk wrapping transmission partially shown in FIG. 1 comprises a pair of conical disks 1 which are arranged non-rotatably on a shaft A on the input side and an output. And a pair of conical disks 2 which are non-rotatably arranged on the side B. Each conical disk pair has axially movable disk portions 1a, 2a and one axially immovable disk portion 1b, 2b, respectively. A winding member in the form of a chain 3 is provided between the two disk pairs for transmitting the rotational moment.

The disk pair 1 can be tensioned via an adjusting member 4 configured as a piston cylinder unit. The pair of conical disks 2 can be tensioned in an analogous manner to the chain 3 via the adjusting member 5.

Operatively in parallel with the piston-cylinder units 4, 5, a further piston / cylinder unit 6, 7 is provided in each case. These piston / cylinder units 6, 7 serve to change the transmission ratio of the transmission. The pressure chambers 6a, 7a of the piston / cylinder units 6, 7 are filled with a pressure medium, for example oil, according to the required transmission ratio or a change in the required transmission ratio, or the pressure chambers 6a, 7a are empty. To be.
For this purpose, the pressure chambers 6a, 7a are connected to a pressure medium supply, for example a pump 8, or to a discharge line 9 as required. When the transmission ratio changes, the pressure chamber 6
a, 7a is filled with a pressure medium. That is, the volumes of the pressure chambers 6a and 7a are enlarged. On the other hand, the other pressure chambers 7a, 6a are at least partially emptied. That is, the volumes of the pressure chambers 7a and 6a are reduced. Pressure chamber 6
This pressure loading or release of a, 7a is effected via a control valve 10.

The control valve 10 is a valve guided back by pressure, and has a slider 44 in the valve casing. In this case, a spring 43 applies an axial force on the slider 44 and a closing device 45 is used to close the slider 44 inside the valve housing.

The valve 10 has various connections. In this case, a connection to the pressure-medium pump 8 or the positive-displacement valve 24 is realized via a connection conduit 46. Further, a reservoir or a non-pressure tank 47 is connected to the valve 10 via the connection pipe 9. Between the tank 47 and the control valve 10, a pressure limiting valve 45 is arranged in the connecting line 9 to increase the back pressure in the discharge line 9. Adjusting member 6 of conical disk pair 1 and 2
a, 7a are connected to the valve 10 via connecting conduits 48, 49. In this case, the conduit 48 is preferably connected to the pair of conical disks on the input side and the conduit 49 is connected to the pair of conical disks on the output side. The connection 42 is used to control the valve 10 with the pre-control pressure in the pressure chamber 41. The pre-control pressure in the pressure chamber 41 can be controlled by the proportional valve 40.

The slider 44 is configured to have a passage 51 in a partial area in the axial direction. The passage 51 is designated by reference numeral 5.
It is open in the radial direction at the location indicated by 2. Another slider 53 is movably arranged in this axial hole. Therefore, the slider 53 can move relatively to the slider 44. In this case, the slider 53
Can be sealed to the slider 44.

The operation of the control valve 10 is as described below. In the illustrated stop position (left side) of valve 10, conduit 49 is connected to conduit 9 and conduit 46 is connected to conduit 4.
8 is connected. As the slider moves axially to the right due to the pressure loading of the chamber 41, the conduit 46 is first blocked and then the conduit 48 is connected to the conduit 9. As the control piston 44 continues to move, the conduit 49 is separated from the conduit 9 and finally the conduit 49 is connected to the conduit 46.

If the pump conduit 46 is connected to the conduit 48, the pressure in the chamber 57 will be at the ring surfaces 50,55.
Act on. In this case, the ring surface 50 is larger,
The axial force component acts against the spring 43, providing an equilibrium between the two forces. When damming pressure is applied to the chamber 41, the piston 44 moves axially and the pressure supplied by the pump is reduced by the control edge at the ring face 50. When the damming pressure is further increased, the conduit 48 is connected to the conduit 9 and the connecting conduit 49 is connected to the conduit 46 to the pump 8. As a result, the passage 56 is likewise filled with a pressure medium and the slider 53 is axially loaded and supported by the member 45. In this case, a force proportional to the pressure and the cross section of the axial bore 56 is generated in the slider 44 towards the pressure chamber 41, whereby a first form of pressure return guide is realized.

When the pressure in the pressure chamber 41 is appropriately selected and the spring force of the spring 43 loads the slider 44 axially toward the pressure chamber 41 and the slider is loaded to the left, the conduit 48 and the conduit 46 A fluid connection is created between This is because the notch 57 forms the connection. As a result, the conduit 49 is connected to the conduit 9. With this slider arrangement, the conduit 48 is loaded with pressure. In this case, the conduit 49 is released. As a result, an axial force directed at the spring is exerted on the slider. In this case, this force is proportional to the area difference of the cross section between the area 55 and the area 50 and is proportional to the pressure in the area 57, while the force in the direction toward the pressure chamber 41 loads the piston 53. This force is multiplied by the cross-sectional area of bore 56 and is proportional to the pressure in conduit 49. This achieves a second form of pressure return guidance.

The tank 46 and the control valve 10 operated without pressure
A pressure control valve 45 provided in the discharge conduit 9 between the pressure control valve and the pressure control valve 45 discharges the pressure medium coming from the conduit 9 to the tank 47 without pressure only when the limit pressure set by the pressure control valve is exceeded. The regulation is effected in the form of a fixedly regulated back pressure which is effective for the entire operating time, but more advantageously this pressure is made controllable and the pressure limiting valve 45 is externally controlled. For example, the control is performed by an electric, hydraulic or pneumatically operated actor. As a result of the connection of the pressure limiting valve 45, the control valve 10 is additionally loaded with a regulated pressure, for example 3-8 × 10 ⁵ Pa, on the pressure limiting valve.
This results in a pressure offset at the adjustment member 6a or 7a connected to the discharge conduit 9. To this, the regulating circuit, which acts on both pressure returns in the valve 10, reacts with a pressure increase in the regulating member connected to the pump 8;
The two adjusting members 6a, 7a are loaded with the same pressure, that is to say with the adjusted pressure on the pressure limiting valve 45, so that the tension of the chain 3 is improved.

As a result, the conical disks 1a, 1b, 2a, 2
Because of the increased frictional engagement between b and the chain, this increased crimp can be applied to the expected or generated rotational moment peaks, e.g. by means of sensor signals, characteristic lines and similar judgments. It is advantageous to control and limit the pressure control valve with a control unit with a reference.

In order to generate at least the pressure associated with the moment, a rotary moment feeler 11 based on the hydromechanical principle is provided. This rotational moment feeler 11 transmits all the introduced rotational moment to the conical disk pair 1. The rotational moment feeler 11 has a cam disk 12 that is immovable in the axial direction but is rotatable only on the axis A, and a cam disk 13 that is movable in the axial direction. Each of the cam disk 12 and the cam disk 13 has a rising ramp, and an expanding body in the form of a sphere 14 is provided between the rising ramps. The cam disk 13 can move in the axial direction on the axis A, but cannot rotate with respect to this axis.

In order to produce the pressure necessary for tensioning the conical disc winding transmission, which is modulated at least in relation to the moment via the rotational moment feeler 11, the pump 8 is connected to the connecting lines 18, 19. , 20 are connected to the pressure chamber 15 of the rotational moment feeler 11. The pump 8 is further connected to the pressure chamber 7a of the piston-cylinder unit 7 in the second pair of disks 2 via a connecting conduit 21 originating from a conduit 20.

Pressure chamber 15 of rotational moment feeler 11
Is connected to the pressure chamber 4a of the piston cylinder unit 4 via at least one passage.

Therefore, the first pressure chamber 15 and the pressure chamber 4a
Is always connected. Furthermore, at least the outflow passage 22 is provided in the shaft A, and this outflow passage 22 is connected to the pressure chamber 15 or can be connected to the pressure chamber 15. The oil flowing out of the pressure chamber 15 via the valve point 23 acting as a throttle can be used for lubricating and / or cooling the components. A ramp or cam disc 13 which is movable in the axial direction on axis A,
A closed area cooperating with the outflow passage 22 is formed. This closing area can more or less close the outlet passage 22 in relation to at least the generated rotational moment. The closed area thus forms a valve or throttle in connection with the outlet passage 22. At least both discs 12,13
The outflow opening or outflow passage 22 is suitably opened and closed via the disk 13 acting as a control piston in connection with the rotational moment occurring during the rotation. As a result, at least a pressure generated by the pump 18 corresponding to the generated moment is generated in the pressure chamber 15. The pressure chambers 15 are connected to the pressure chambers 5a via passages or conduits 20, 21 in addition to the pressure chambers 4a, so that a corresponding pressure is generated in these pressure chambers 4a, 5a.

Based on the fact that the piston-cylinder devices 4 and 5 are connected in parallel with the piston-cylinder devices 6 and 7, the pressure sent from the rotational moment feeler 11 can be applied to the axially movable disks 1a and 1a. In addition to the force generated in 2a, it forms a force acting on these disks 1a, 2a to adjust or change the transmission ratio of the transmission based on the pressure present in the chambers 6a, 7a.

The pressure chambers 1 which are operatively parallel in the event of a pressure load
5 and 16 can be connected to each other or separated from one another in relation to the change in the transmission ratio of the conical transmission. This connection or disconnection can be made in connection with the axial movement of the disk 1a. For this purpose, the disk 1a is used as a valve part, and a considerable coupling passage can be provided in the shaft A and in the components of the disk pair or the rotary moment feeler 11. Advantageously, only the first pressure chamber 15 is loaded with pressure over at least approximately the entire deceleration sub-region (UD or underdrive region) of the transmission region of the transmission. Both pressure chambers 15,1
The connection of 6 takes place in an advantageous manner at least approximately at the transition of the transmission region of the transmission into the speed-up region (OD or overdrive region). Therefore, both pressure chambers 1
The connection or disconnection between 5 and 16 advantageously takes place with a transmission ratio of approximately 1: 1 of the transmission. Thus, the torque sensor 11 can produce a pressure modulation related to the transmission ratio superimposed on the pressure modulation related to the torque. In practice, the modulation associated with the transmission ratio of pressure or pressure level is performed in two stages.

From the preceding functional description, it can be seen that the axial force generated by the ball ramps provided on the disks 12, 13 over the entire transmission subregion (underdrive) in which the transmission is shifted to deceleration. However, while being supported by the axially effective surface formed by the pressure chamber 15, the disk 13 has a ball ramp over the entire transmission range (overdrive) in which the transmission is shifted to an increased speed. The axial forces generated by the pressure chambers are received on both axially acting surfaces of the pressure chambers 15,16. Thus, for the same input moment, the pressure generated by the rotational moment feeler 11 when shifting the transmission to deceleration is less than the pressure generated by the rotational moment feeler 11 when shifting the transmission to increase speed. Will also be higher. In this case, the transmission is designed in such a way that the switching point for connection or disconnection between the two pressure chambers 15, 16 is located in the region of a transmission ratio of about 1: 1.

As regards further structural features and operational features of the wrapping transmission with the rotary moment feeler 11, German Patent Application DE-OS 444 333.
See No. 2. This document describes another configuration of a rotational moment feeler that can be used in an advantageous manner in connection with the present invention. Furthermore, in connection with the present invention, it is also possible to use a rotational moment feeler such as is known from the state of the art mentioned at the outset. Although a single-stage rotational moment feeler can be used, in order to improve the efficiency of the transmission, as described above, at least the transmission ratio or the transmission-related change in the transmission ratio is required over the entire transmission range of the transmission. Advantageously, not only a two-stage or multi-stage pressure modulation but also a stepless pressure modulation is present.

As can be seen from FIG. 1, the pressure medium can be supplied to all the adjusting members 4, 5, 6, 7 and the rotational moment feeler 11 by a single pump 8. Behind the pump 8, a volume flow restriction valve 24 is first arranged. In this case, volume flow restriction, ie, valve 24, is not necessary. This is the case, for example, when a pump 8 is used which is variable with respect to the volume to be conveyed. A valve 10 for adjusting the transmission ratio and a valve 25 for adjusting the pressure are connected behind the volume limiting valve 24. Valve 25 is provided to increase the pressure in front of valve 10 or in conduits 18,19. Depending on the valve 25, the pressure in the conduit 19 or in front of the valve 10 causes the transmission ratio regulating valve 10
On the one hand with the adjusting member 6 and on the other hand with the adjusting member 7
The working pressure in both conduits 26, 27 connecting the two is controlled to be greater than the higher required pressure. The pressure-increasing valve 25 is connected on the one hand via the line 20 to the rotational moment feeler 11 and the adjusting member 4, and on the other hand to the adjusting member 5 via the line 21. Valve 2
The connection between 5 and the adjusting member 4 does not necessarily have to be made via the rotational moment feeler 11. Conduit 20,2
The pressure present or generated in the pressure chambers 1 or the pressure chambers 4 a, 5 a is related to the pressure sent from the rotary moment feeler 11 or the rotary moment transmitted by the rotary moment feeler 11. In order to ensure a satisfactory operation of the transmission, the pressure in front of the valve 10, ie in the conduit 19 or 18, regulates the transmission required in the conduits 26, 27 or in the pressure chambers 6a, 7a. It is kept higher than the higher pressure. The pressure required to adjust the transmission is determined by the torque
It is possible to be higher than the pressure sent from. This means that under many operating conditions or driving conditions, the pressure provided by the rotational moment feeler is too low for the rapid adjustment of the transmission ratio of the conical-disk winding transmission required for satisfactory operation. Means that. This is the case, for example, when braking with a small engine moment, i.e. in the case of rapid deceleration and in the case where an adjustment speed with a high transmission ratio is required. Due to the fact that the torque to be transmitted by the torque sensor is too small, the torque sensor delivers a relatively small pressure. This pressure is insufficient to ensure the necessary quick adjustment of the transmission ratio of the transmission. In this operating condition, in order to set or ensure a sufficiently high pressure in front of the valve 10, ie in the conduits 18, 19, and thus in at least one of the conduits 26, 27, the pressure-increasing valve 25 has a rotational moment. Feeler 11 or conduit 2
0, 21 and the valve 10 or the conduit 19. Via this valve 25, it is ensured that the pressure in the conduit 19 or the valve 10 is higher by a predetermined value than the higher of the two pressures in the conduits 26, 27. For this purpose, the valve 25 must be at least connected to the line 1 under the corresponding operating conditions.
Between 9 and 20, there is a control member 28 which causes the throttling effect of the valve 25. The control member 28 is controlled or actuated by directing the pressure formed in the conduits 26, 27 back as shown.

The direct return guide is on the one hand a conduit 26, 2
7, and on the other hand via conduits 29, 30 connected to the Or regulating member formed by valve 28. Valves 25 and 28 each have sliders 31, 32 received in holes. These sliders 3
1, 32 can be moved axially independently, i.e. independently of one another. The slider 31 is supported by the slider 32 via a spacer pin 33. One pressure chamber 34, 35 is provided on each side of the slider 32.
These pressure chambers 34, 35 are connected to suitable conduits 29, 30. As a result, the pressure chamber 35 is disposed between the sliders 31 in the axial direction. Conduit 2
At 7, and thus also at the conduit 30, if a higher pressure acts, this pressure acts on the pressure chamber 35 and thus directly on the slider 31 of the valve 25. On the other hand, if the pressure in the conduit 26 and thus also in the conduit 29 is higher than the pressure in the conduit 27 or 30, the pressure created in the pressure chamber 34 will cause the slider 32 to move, thereby also 31 is loaded or actuated in the closing direction.
As a result, the valve 28 or the slider 32 functions as an Or member. This means that only a force corresponding to the higher pressure in the conduits 26, 27 is transmitted to the slider 31 or the pressure-increasing valve 25 at all times.

Furthermore, the valve devices 25 and 28 have an energy storage device formed by a spiral spring 36.
The energy storage device is biased, the energy storage device being supported on the one hand via a plate 37 on the valve housing and on the other hand on the slider 31. Spring 3
A spacer pin 33 is provided in 6. Spring 36
Is set so that the pressure in the conduit 19 and thus the pressure in front of the transmission ratio valve 10 does not fall below a predetermined pressure. As a result, a minimum pressure always exists before the transmission ratio valve 10. The spring 36 of the slider 31
Another pressure chamber 38 exists on the opposite side. This pressure chamber 38 is connected to a conduit 39, which itself likewise opens into a conduit 18 or 19. Accordingly, a pressure corresponding to the pressure in the conduit 18 or 19 is generated in the conduit 39. As a result, a suitable axial force is generated in the slider 31 in the pressure chamber 38 against the force generated by the spring 36. When the required minimum pressure is reached in the conduits 18 or 19, depending on the connecting conduit 39 and the pressure chamber 38, the connection to the conduits 20, 21 or the rotational moment feeler 11 is released. Because the slider 31 is pressure-loaded on both sides,
A pressure equilibrium or difference between the highest pressure occurring in 6 and 27 and the pressure occurring in conduits 18, 19 or in valve 10 is provided. The spring 36 or the valves 25 and 28 is the desired pressure between the maximum pressure occurring in the conduit 26 or 27 and the pressure before the valve 10 in addition to the minimum pressure occurring in the conduit 18 or 19 or before the transmission ratio valve 10. Determine the difference.

The valve 10 is actuated by a control pressure set by a proportional valve 40. For this, the valve 10 is connected to the conduit 4
2 and a pressure chamber 41 connected to the proportional valve 40 via the pressure chamber 41. A preload spring or a return spring 43 is arranged on the side opposite to the pressure chamber 41. In the case of a pressure-free chamber 41, the slider 44 is connected via a spring 43, on the one hand, between the conduit 27 and the discharge conduit 9, and on the other hand, between the conduit 26 and the conduit 19 or 18. Is brought to a position where As a result, the conduit 27 is pressure-free in practice, whereas in the conduit 26 the pressure is applied via the force balance between the pressure acting on the ring surface and the spring force of the spring 43,
The adjustment is then made via a suitable equilibrium position of the piston 44, whereby an adjustment in the "overdrive" direction is made.

When pressure is applied to the chamber 41, the slider 44
Is moved to the right against the force of the spring 43,
The valve 10 is correspondingly adjusted or controlled in accordance with the equilibrium between the blocking pressure in 1 and the pressure acting on the surfaces 56,50. If the pressure in the chamber 41 is full, on the one hand the conduit 27 is connected to the conduit 18 or 19 and on the other hand the conduit 26 is connected to the discharge conduit 9. This results in a regulated pressure at the pressure limiting valve 45, which is added to the regulated supply pressure in the conduit 27, whereas the conduit 2
6 is loaded only with the pressure regulated at the pressure limiting valve 45. As a result, the transmission is adjusted in the direction of "underdrive".

By appropriate adjustment of the pressure in the pressure chamber 41 or in the conduit 42, the pressure in the conduits 26, 27 is selectively adjusted between the discharge pressure and the maximum supply pressure.

The pressure in conduits 26 and 27 is regulated by proportional valve 40 in relation to the desired transmission ratio. The proportional valve 40 is controlled via an electronic control which processes various parameters, for example the transmission ratio of the transmission, or which has as input values. The transmission ratio of the transmission is determined, for example, by detecting and comparing the input-side rotational speed, for example, the rotational speed of the shaft A and the output-side rotational speed, for example, the rotational speed of the shaft B. Other parameters that can be taken into account are the position of the gas pedal or the amount of fuel supplied, the negative pressure in the intake system of the engine, the load condition of the drive engine and the like.

In an advantageous manner, the valve 10 can be formed by a 4/3 valve. This 4/3 valve can be configured as a quadrilateral slide valve. Instead of a hydraulically controlled transmission ratio valve 10, an electrically or pneumatically controlled magnet valve can also be used. A directional control valve with an electromagnetic actuator can be used in an advantageous manner. In this case, the directional control valve can likewise have a return spring.

The invention is therefore not limited to the embodiment shown, but rather to the valves 10, 24, 25 and 28 described.
Instead of this, it is also possible to use valves which are controlled in other ways or to combine these valves or to guarantee the described function of the individual valves by using correspondingly corresponding valves. For example, the transmission ratio valve 10 is connected to the conduits 26 and 27 and the conduit 18.
Alternatively, it may be replaced by a valve which forms a connection with 19 and is appropriately controlled.

FIG. 2 shows a part of one device in the form of a variant of the winding transmission shown in FIG. In this case, it should be understood that components not shown or described are the same as those in FIG.

Control valve 11 with conduits 148, 149 for loading the regulating members provided for transmission ratio control
0 has a discharge conduit 109 which is connected to a supply conduit 142 of a proportional valve 140 which controls the control valve 110. In this manner, both discharge conduits 10
9a, 109b are loaded with additional pressure. In this case, the conduit 148 or 149 connected to the supply conduit 146
In the above, a suitable pressure increase is made by the pump 108 indirectly. The pressure increase in the line 149 or 148 connected to the supply line 109, which is pressure-loaded by the pressure-reducing mechanism of the valve 10 acting in a regulating manner, is compensated again by the increase in pressure in the line connected to the pump 108. You.

For example, a valve 160 is provided for preparing a constant pressure that can be adjusted in the range of 3-8 × 10 ⁵ Pa. The valve 160 has a return connection loop 162 with throttles 161 and 161a. This return connection loop 162 regulates the flow to conduits 109, 142 for pressure regulation and stabilization by axial movement of piston 163 in response to the pressure generated by pump 108.

Such an arrangement is provided for preparing a constant pressure for increasing the pressing pressure. Proportional valve 14
Since a small pressure medium flow of constant pressure is supplied to the zero via the throttle 164, the proportional valve 140 can control the valve 110 with the control pressure changed thereby. Openings 165 and 166 are provided in the wrapping transmission to supply additional components.

FIG. 3 shows a variation of the winding transmission shown in FIG. 1 in a modified configuration for increasing the pressure in the discharge conduit at valve 210. In the embodiment shown, the required pressure is taken from-in the direction of flow-the blocking pressure generated in the conduit 268 in front of the suction jet pump 267. In this case, the conduit 268 is connected to the discharge conduit 209 of the valve 210. This pressure rise is converted according to the embodiment of FIGS.

The suction jet pump 267 is connected to the conduit 2
The check valve 2 due to the blocking pressure generated at 68 or the suction jet thereby generated in the conduit 271
A pressure medium is sucked from the reservoir 270 against the action of 69,
This is conveyed in a conduit 271, for example, to a cooling device.

In this case, the blocking pressure in conduit 268 only occurs when valve 272 is open. This is because the bypass conduit 273 bypassing the valve 272 is provided with a restriction 274.
This is because the throttle 274 has an opening that can be compared with the nozzle of the suction jet pump. The supply conduit 275 conveys the pressure medium to the valve 272 with residual pressure from the process occurring in the wrapping transmission, for example from the adjusting element of the disk crimp associated with the moment or from a rotational moment feeler or the like. This valve 272
The pressure medium is supplied to the inlet of the pump 208-advantageously bypassing the fines filter 276-or directed to a conduit 268 for cooling.

Control of valve 272 is undertaken by proportional valve 277. The proportional valve 277 is supplied with a constant pressure via a conduit 278 and is controlled by a control unit (not shown). Control is performed hydraulically by applying a pressure to chamber 279 proportional to the axial adjustment distance of valve 272. The proportional valve 277 is provided, for example, when a clutch that can be disposed between the driving member and the input-side disk pair slips,
Is switched to conduit 268 and the pressure medium coming from conduit 275 coming from the cooler not shown
Via 8, a supply is provided to the clutch from the reservoir 270 in order to extract frictional energy in the conduit 271 under the supply of another pressure medium.

The use of this damping pressure to load the conduit 209 with pressure is particularly advantageous insofar. Because of the slipping of the clutch, the connection of the drive unit cannot be made completely, so that the rotational moment peak on the output side causes a large acceleration in the disc pair without the traction moment of the drive unit, This acceleration can lead to slippage of the chain. In this operating state, temporarily
By increasing the pressure in the discharge conduit 109 of the valve 210, additional crimping and tensioning of the chain is achieved.

FIG. 4 shows a sectional view of a control valve for controlling the pressure of the regulating device, for example, a device 300 for increasing the pressure at the control valve 10 of FIG. In this case, the pressure limiting valve 45 is removed, and instead the device 300 is inserted in the conduit 9 between the pressure medium reservoir 47 and the control valve 10. For this purpose, the conduit 9 (FIG. 1) is connected to the supply conduit 309 and the discharge conduit 347 is connected to the pressure medium reservoir 47 (FIG. 1).

The device 300 is arranged on a drive shaft B on the output side of the conical disk winding transmission and has a rotary mass 350 rotatably arranged on a shoulder 351 of the drive shaft B. . In this case, the rotating mass 350 has an internal thread 352, which forms a positive connection with the external thread 353 of the drive shaft B, so that the rotating mass 350 is When the rotary mass is relatively rotated based on the inertia of the rotary shaft, the rotary mass 350 moves in the axial direction along the threads of the threads 353 and 352. In an advantageous manner, the positive connection between the two components B, 350 is, for example, one of the components A
Or both components which are formed in consideration of the required turning distance by means of a threaded key at 350 and correspondingly notched grooves in the complementary component, or on which a guide element, for example a ball, is mounted B, 350 can also be formed by grooves cut out.

The axial movability of the rotating mass is limited in one direction by a stopper shoulder 354 provided on the drive shaft B and in the other direction axially by the casing 3.
It is limited by a stop 357 provided on the sliding ring 355, which bears on the shoulder 56, and is provided on the ring shoulder. In this case, the sliding ring 355 compensates for different rotational speeds of the casing 356 and the rotating mass 350.

The casing 356, which is fixed with respect to the drive shaft B and the rotary mass 350, can be fixed and fixedly connected to or a part of a transmission casing (not shown). , This casing 356
Forms a chamber 358 with the rotating mass 350 and the drive shaft B. In this case, these parts are mutually connected to the sealing member 35.
It is tightly sealed via 9,360.

The rotating mass 350 is axially loaded by the energy storage device 361 in order to fix the equilibrium state when the drive shaft B stops and rotates uniformly. In the illustrated embodiment, the rotating mass 350 is a coil compression spring 3 supported on the drive shaft B.
It is fixed to the stopper 354 by 61. The known spring receiver which couples components B, 350 is not shown.

The mode of operation of the device 300 will be described below with reference to FIGS. In this case, it is assumed that the device 300 is arranged instead of the pressure limiting valve 45.

In a normal operation state where there is no rotational moment impact acting on the drive shaft B, the rotating mass 350 rotates in the same phase as the drive shaft B. In this case, the force constant of the energy storage device 361 changes when the rotational speed of the drive shaft B changes.
Are set so as not to have a relative rotation with respect to the drive shaft B based on friction generated between the drive shaft B and the rotating mass 350. The control valve 10 is supplied by a pump 8 with a pressure medium for creating a pressure force associated with the transmission ratio of the conical disk pair 1, 2, and excess pressure medium is supplied to the pressure reservoir 4.
It is led out via conduit 9 at 7.

For example, when a rotational moment impact is generated by an impact load of the drive gear, relative rotation with respect to the drive shaft B occurs due to the inertia of the rotating mass 350. This causes the rotating mass 350 to move axially along the thread lead against the action of the energy storage device 361. In this case, in this embodiment, the threads 352, 35
The third thread lead is oriented opposite to the direction of rotation of the drive shaft.

By the axial movement of the rotating mass 350,
The rotating mass 350 approaches the sliding ring 355, if necessary, until it comes into contact, with the connection 309 of the pressure medium from the conduit 9 to the connection to the pressure medium reservoir.
7 is reduced in relation to the magnitude of the rotational moment impact. This likewise produces an increased pressure on the control valve 10 which leads to an increase in the pressure of the pair of conical disks 1,2. When the rotational moment impact is reduced, the rotating mass is returned to the stopper 354 again by the action of the energy storage device 361.

The embodiment of the pressure increasing device 400 of FIG.
Is similar in principle to the embodiment 300 of FIG.
At the same time, it has a rotating mass 450 arranged in a notch 458, which is a chamber for the pressure medium. Therefore, room 458
Is formed only by the drive shaft B and the rotary mass 450, and is provided in the drive shaft B with a supply portion 4 from a control valve (the control valve 10 in FIG. 1).
09 and a discharge portion 447 to a pressure medium reservoir (the pressure medium reservoir 47 in FIG. 1) extending along the rotation axis.

Between the drive shaft B and the rotary mass 450 there is provided a thread 453 or equivalent, for example as described with reference to FIG. By these means, the rotating mass 4
Reference numeral 50 denotes an energy storage device 461 configured as a coil compression spring when rotated relatively to the drive shaft B.
In the axial direction against the action of In this case, the rotating mass 450 is provided with a stopper shoulder 4 provided on the drive shaft B for a stopper ring 450a which is enlarged radially outward.
It is restricted and movable in the axial direction by the stopper 54 and the stopper 455 of the cover 452. The rotating mass 450 has a protrusion 457 extending in the axial direction at the height of the rotation shaft.
7 cooperates with the discharge conduit 447 from the supply conduit 409 to the discharge conduit 447 during the axial movement of the rotating mass 450.
Acts as a control edge that controls the flow of pressure medium to the

When the drive shaft on the output side is suddenly decelerated based on the rotational moment impact, the rotary mass is further rotated from the equilibrium state determined by the stopper 455 by the coil compression spring 461 due to the inertia, and the screw thread is formed. It is moved axially along the 453 screw lead. As a result, the hydraulic cross section of the discharge conduit 447 is narrowed by the projection 457 and, in extreme cases, closed. Thereby, the control valve 10
, And consequently the crimping force on the pair of conical disks 1, 2 (FIG. 1) is raised shortly until the rotational moment impact subsides. After the rotational shock has subsided, the return action of the coil compression spring 461 on the rotating mass 450 causes the conduit cross-section at the discharge conduit 447 to be fully expanded, and the crimping pressure increased in relation to the magnitude of the rotational moment shock. The pressure is returned to the normal pressure.

The devices 300 and 400 in FIGS. 4 and 5 and / or alternatively the pressure limiter 45 and / or the pressure conduits 109 (FIG. 2) and 209 (FIG. 3) in FIG. Can be connected to other discharge conduits leading to the For example, the described pressure increasing means 300, 400, 4
At least one of the five or rotational moment feelers 1
The conduits 109, 209 which conduct the higher pressure between the pressure member 1 (FIG. 1) and the adjusting member 6 (FIG. 1) and / or between the rotational moment feeler 11 and the pressure medium reservoir are advantageously connected. it can. This increases the pressure in the crimping chamber and thus leads to an increased crimping of the wrapping means 3.

The following patent application, namely DE-OS195
No. 44644, DE-OS 19546293, DE-
OS19546294, DE-OS19721036
The contents of the specification are fully contained in the present patent application.

The claims filed in this application are proposals and do not imply a waiver of achieving protection of another patent. Applicant reserves the right to apply for a patent for any other feature previously disclosed merely herein in the specification text and / or drawings.

Citation of other claims used in dependent claims suggests a further development of an independent claim with the features of each dependent claim. In other words, this does not mean an abandonment of the independent and specific protection of the features of the cited dependent claims.

The subject matter of these dependent claims also constitutes an independent invention having a configuration independent of the subject matter of the preceding dependent claim.

The present invention is not limited to the embodiments described in the specification. Rather, many changes and modifications are possible within the framework of the invention, in particular the features or members or methods described or shown in connection with the description and examples throughout the specification and claims. Variations of embodiments, members and combinations and materials that result in new objects or new method steps or sequence of method steps due to features that are inventive and can be combined by combining with steps or altering these features or elements or method steps, Manufacturing, inspection and working methods are also possible.

[Brief description of the drawings]

FIG. 1 shows a continuously adjustable winding transmission with a pressure limiting valve for increasing the back pressure at the control valve.
The figure which showed the part.

FIG. 2 shows a section of a continuously adjustable winding transmission having a connection to the supply line of a proportional valve for increasing the back pressure at the control valve.

FIG. 3 shows a part of a continuously adjustable winding transmission with a connection to a suction jet pump for increasing the back pressure of the control valve.

FIG. 4 is a cross-sectional view of the upper half of one embodiment of an apparatus for increasing pressure at the outlet of a control valve.

FIG. 5 is a cross-sectional view of another embodiment of the device for increasing the pressure at the outlet of the control valve.

[Explanation of symbols]

1 conical disk pair, 2 conical disk pair, 3 winding member, 4 adjusting member (piston cylinder unit),
5 adjustment member (piston cylinder unit), 6 piston cylinder unit, 7 piston cylinder unit, 8 pump, 9 discharge conduit, 10 control valve,
11 Rotary moment feeler, 12 Disk, 1
3 discs, 15 pressure chambers, 16 pressure chambers, 18
Conduit, 19 conduit, 20 conduit, 21 conduit, 2
4 volume limiting valve, 25 pressure increasing valve, 26 conduit,
27 conduits, 28 control means, 29 conduits, 3
0 conduit, 31 slider, 32 slider, 3
3 Spacer pin, 34 pressure chamber, 35 pressure chamber,
36 spring, 40 proportional valve, 41 chamber, 42 conduit, 43 return spring, 44 slider, 45 pressure limiting valve, 46 connection, 47 tank, 48
Connection, 49 connection, 51 passage, 53 slider, 55 ring surface, 108 pump, 109
Discharge conduit, 110 control valve, 140 proportional valve,
142 supply conduit, 146 conduit, 148 conduit,
149 conduit, 160 valve, 161 throttle, 1
61a throttle, 162 return connection, 163 piston, 165 opening, 166 opening, 208 pump, 209 discharge conduit, 210 valve, 267 suction jet pump, 268 conduit, 269
Check valve, 270 reservoir, 271 conduit, 272
Valve, 273 bypass conduit, 274 throttle, 275
Supply conduit, 276 fine substance filter, 277
Proportional valve, 278 conduit, 279 chambers, 300 units, 309 supply conduit, 347 discharge conduit, 35
0 rotating mass, 351 shoulder, 352 female thread,
353 Male thread, 354 Stopper shoulder, 355
Sliding ring, 356 casing, 357 stopper, 358 chamber, 359 sealing member, 360
Sealing member, 361 Coil tension spring, 400
Pressure riser, 409 supply conduit, 447 discharge conduit, 450 rotating mass, 452 cover, 453
Thread, 454 stopper shoulder, 455 stopper, 457 protrusion, 458 chamber, 461 energy storage

Continued on the front page (72) Inventor Günter Ebinger Germany Reinmünster-Stolhofen im Erlengrund 9 (72) Inventor Ludger Holtmann Karlsruhe Karlstrasse 82 Germany 82

Claims (28)

[Claims] 1. A continuously adjustable slewing gear, in particular a slewing gear for a motor vehicle, comprising a drive shaft connected to a drive member on the input side and at least one drive gear on the output side. A pair of conical discs, each of which is connected to an endless winding member for drivingly connecting the two conical disc pairs, at least one cone of one conical disc pair The disc is movable in the axial direction and is pressure-loaded with a supply of pressure medium by at least one hydraulic adjusting element in each case for adjusting the transmission ratio and / or the transmission of the moment. The pressure is regulated by means of at least one control valve arranged between the pressure supply device and the regulating member, and an opening in the pressure medium reservoir is provided for the hydraulic pressure medium that is not required. Exhaust Continuously adjustable winding transmission, characterized in that the outlet line and / or the pressure medium reservoir can be loaded with back pressure, in the form of an outlet line. 2. Two adjusting members are provided for each pair of conical disks, one adjusting member for supplying pressure for transmitting the moment and one adjusting member for controlling the transmission ratio. 2. The wrapping transmission according to claim 1, wherein the transmission is adapted to supply an adjusting pressure and the control valve controls an adjusting member for adjusting the transmission ratio. 3. The wrapping transmission according to claim 1, wherein the control valve is a differential pressure valve, and supplies a differential pressure to the adjustment member that controls a transmission ratio. 4. The winding transmission according to claim 1, wherein the pressure load is performed at least by using a pressure limiting valve. 5. The winding transmission according to claim 1, wherein the pressure limiting valve is adjustable and / or controllable. 6. The wrapping transmission according to claim 1, wherein the adjustment of the pressure limiting valve is performed mechanically, hydraulically, electrically or pneumatically. 7. The pressure valve according to claim 1, wherein the pressure load is at least provided at a pressure which is provided for supplying a solenoid-operated switching valve, for example a proportional valve or a PWM valve. The wrapping transmission according to the item. 8. The winding transmission according to claim 1, wherein the electromagnetic switching valve controls a control valve. 9. The winding as claimed in claim 1, wherein the supply conduit of the proportional valve is connected to the discharge conduit of the control valve to the pressure medium reservoir or to the pressure medium reservoir. Hanging transmission. 10. The method according to claim 10, wherein the pressure load is performed at least with a damming pressure generated by a suction jet pump.
In particular, a winding transmission according to any one of the preceding claims. 11. The suction pressure of the suction jet pump is generated only in a predetermined operating state, whereby the back pressure is generated during the operating state.
The winding transmission according to any one of claims 1 to 10. 12. When the clutch disposed between the driving member and the pair of conical disks on the input side slips or rubs, the suction jet pump generates a blocking pressure.
A wrapping transmission according to any one of the preceding claims. 13. The device according to claim 1, wherein the pressure load is controlled by a device which controls the flow in the discharge line in relation to the rotational moment shock occurring on the output drive shaft. The wrapping transmission according to the item. 14. Apparatus for pressure-loading said control valve is at least a rotating mass which is constrained and rotatably arranged on said drive shaft and is axially shiftable, and discharges to a pressure reservoir. A chamber for forming a valve volume having a conduit and a supply conduit from the control valve, wherein the rotating mass shifts axially upon a rotational moment impact between the control valve and the pressure medium reservoir. 14. The winding transmission according to claim 1, which controls a conduit cross section of the conduit. 15. The wrapping transmission according to claim 1, wherein the rotary mass and the drive shaft are rotatable with each other restricted via a thread. 16. The winding transmission according to claim 1, wherein the rotating mass is pivoted against an axially effective return action of the energy storage device. 17. The winding transmission according to claim 1, wherein the energy storage device is a coil compression spring or a coil tension spring. 18. The winding transmission according to claim 1, wherein the chamber is formed by the rotating mass and the drive shaft. 19. The wrapping transmission according to claim 1, wherein the chamber is formed by the rotating mass, the drive shaft and a stationary casing part. 20. The winding transmission according to claim 1, wherein the pressure load is controlled by a control unit. 21. The control according to claim 1, wherein the control is performed in relation to the pressure required at the adjusting member.
The winding transmission according to any one of the preceding claims. 22. An adjustment value for said back pressure is provided in advance by a control device, said adjustment value being related to the required pressure at said adjustment member and being calculated from at least another operating parameter. Or estimated,
22. A wrapping transmission according to any one of the preceding claims. 23. The winding transmission according to claim 1, wherein the further operating parameter is a sensor signal or another provided adjustment value. 24. The sensor signal is generated by a sensor that detects rotation of at least one drive gear.
A wrapping transmission according to any one of claims 1 to 23. 25. The winding transmission according to claim 1, wherein the sensor detects uneven gear rotation or a gear block. 26. The winding transmission according to claim 1, wherein the sensor signal is generated by a sensor for detecting slippage of the winding member on the conical disk. . 27. The wrapping transmission according to claim 1, wherein the sensor signal is formed from a difference in rotation between the two conical disk pairs, so that an unavoidable difference in rotation is compensated for in the transmission. apparatus. 28. A continuously adjustable winding transmission,
A winding transmission, in particular for a motor vehicle, comprising a pair of conical disks, each of which is connected on the input side to a drive element and on the output side to a drive shaft for at least one drive gear, is a biconical circle. For tensioning an endless wrapping member for drivingly connecting the plate pairs, wherein at least one of the conical disks of one conical disk pair is axially movable and has a transmission ratio and / or momentum. The pressure of the pressure medium is supplied by at least one hydraulic control element in order to regulate the transmission of the pressure, the pressure being supplied by at least one pressure supply device and the pressure supply device In the form of regulation by means arranged between the regulating member and a discharge conduit to a pressure medium reservoir for receiving excess pressure medium and / or the pressure medium reservoir is negatively influenced by back pressure. Possible, characterized in that a continuously adjustable belt-driven.