Actuating device

Abstract

Actuating device for actuating a clutch (38) for coupling a drive shaft of a motor vehicle engine with a transmission input shaft of a motor vehicle transmission, with an actuator (12) for triggering an actuation of the clutch (38), wherein the actuator (12) has an extendable actuator plunger (14), a master cylinder (20) which can be actuated directly or indirectly by the actuator tappet (14) for imposing a pressure change in a pressure chamber connected to the master cylinder (20) hydraulic line (24) connected to the displacement of an actuating element (40) of the clutch (38) and a compensation spring (32) provided outside the actuator (12) for increasing a maximum actuating force that can be exerted by the actuator tappet (14) on the master cylinder (20).

Description

[0001] The invention relates to an actuating device with the aid of which a clutch for coupling a drive shaft of a motor vehicle engine to a transmission input shaft of a motor vehicle transmission can be actuated, as well as to a clutch system with such an actuating device.

[0002] DE 10 2011 084 840 A1 discloses a motor vehicle drivetrain in which an actuating element of a friction clutch, designed as a lever spring, can be pivoted by an actuating device. The actuating element engages a pressure plate of the friction clutch, so that the pressure plate can be axially displaced when the actuating element is pivoted to open and close the friction clutch. Additionally, a compensation spring supported on a clutch housing engages the axially displaceable pressure plate, the spring force of which can influence the required actuating force for actuating the friction clutch.

[0003] There is a constant need to be able to adapt clutch systems cost-effectively to different load conditions of different drive trains.

[0004] The object of the invention is to demonstrate measures that enable a cost-effective adaptation of clutch systems to different load conditions of different drive trains.

[0005] The object is achieved according to the invention by an actuating device having the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which may each individually or in combination represent an aspect of the invention.

[0006] According to the invention, an actuating device for actuating a clutch for coupling a drive shaft of a motor vehicle engine to a transmission input shaft of a motor vehicle transmission is provided with an actuator for triggering an actuation of the clutch, wherein the actuator has an extendable actuator tappet, a master cylinder which can be actuated directly or indirectly by the actuator tappet for imposing a pressure change in a hydraulic line connected to a master cylinder for displacing an actuating element of the clutch and a compensation spring provided outside the actuator for influencing, in particular increasing, a maximum actuating force which can be acted upon by the actuator tappet on the master cylinder.

[0007] The compensation spring can act directly or indirectly on the actuator tappet and / or a master piston of the master cylinder that can be retracted into the master cylinder in order to influence the actuating force acting on the master cylinder or the master piston of the master cylinder. With the help of the compensation spring, the actuating pressure arriving at the master cylinder, the pressure in the hydraulic line, and the actuating pressure in a slave cylinder connected to the hydraulic line, which acts on the clutch to open and / or close the clutch, can be influenced outside the clutch. This makes it possible, in particular, to actuate a clutch that requires a particularly high actuating force for a specific motor vehicle drivetrain.Furthermore, it is possible to use the same actuator for different required actuation forces on the clutch, and to compensate for differences in the required actuation force and the force that can be applied by the actuator using the compensation spring. If the actuator provides too little force at least in part of the travel range, the compensation spring can apply an additional force to achieve a correspondingly higher actuation force on the clutch. If the actuator provides too much force at least in part of the travel range, the compensation spring can apply an opposing force to achieve a correspondingly lower actuation force on the clutch.The compensation spring is located outside the actuator and not inside the actuator, so that by replacing the compensation spring, the clutch system consisting of the clutch, the actuating device, and the hydraulic system can be easily adapted to different load conditions, such as those that may arise for different drive trains. This adaptation does not require any design changes to the interior of the clutch or actuator, so that the clutch system can be easily configured using cost-effective standard components, and only the easily accessible compensation spring needs to be replaced depending on the application. The simple replacement of the easily accessible compensation spring located outside the clutch and the actuator enables cost-effective adaptation of clutch systems to different load conditions of different drive trains.

[0008] The compensation spring can be supported on a stationary component, for example a clutch bell housing or a housing of the actuator. The compensation spring acts with its spring force on the extendable actuator tappet of the actuator and / or a master piston of the master cylinder, so that the spring force of the compensation spring already contributes to the actuating force acting on the master cylinder. The master cylinder is connected to a slave cylinder via the hydraulic line. The slave cylinder has, for example, a slave piston, in particular an annular one, which can be extended as a result of a pressure change in the slave cylinder and which can act on an actuating element of the clutch. The actuating element of the clutch is, for example, an axially displaceable actuating pot and / or a pivotable lever, for example a lever spring designed as a disc spring.The actuating element can, for example, act directly or indirectly on a pressure plate of a clutch configured as a friction clutch in order to frictionally press a clutch disc between the pressure plate and a counterplate of the friction clutch. This allows torque to be transmitted between the counterplate and the clutch disc, so that the drive shaft of the motor vehicle engine can be coupled to the at least one transmission input shaft of the motor vehicle transmission. Since the compensation spring already acts on the actuator tappet at the force output of the actuator and / or on the master piston at the force input of the master cylinder, the spring force acting on the compensation spring can also be captured by a possibly provided force transmission of the hydraulic path formed by the master cylinder, the hydraulic line, and the slave cylinder.The actuator can be actuated, in particular, by a transmission control of an automatic transmission and / or by actuating a clutch pedal of a manual transmission to extend or retract the actuator tappet. For example, the actuator has an electric actuator motor to displace the actuator tappet and provide a significant portion of the actuating force acting on the master cylinder. The hydraulic line can have a compensating reservoir, in particular communicating with the master cylinder and / or the hydraulic line, in order to compensate for volume changes of a hydraulic medium, in particular oil.

[0009] In particular, the compensation spring acts on the actuator tappet and / or a master piston of the master cylinder via a compensation lever, wherein an angular position of the compensation lever depends on a displacement of the actuator tappet in the actuator. The spring force of the compensation spring acting on the actuator tappet or the master piston can be additionally translated via the compensation lever. This allows the compensation spring to exert a non-linear force on the actuator tappet and / or the master cylinder indirectly via the compensation lever. By appropriately selecting the relative arrangement and orientation of the compensation lever and the compensation spring, the spring force of the compensation spring acting on the actuator tappet and / or the master cylinder can be deliberately adjusted via the stroke of the actuator tappet in order to achieve a specific characteristic curve of the actuating force depending on the stroke of the actuator tappet.This can, for example, prevent peaks in the required actuating force that would otherwise occur and exceed the maximum actuator force. For example, it is possible to use the actuator force to preload the compensation spring in a stroke range of the actuator plunger where only a low actuating force is required, and to release the energy stored in the compensation spring in a stroke range of the actuator plunger where a particularly high actuating force is required, possibly exceeding the maximum actuator force.

[0010] Preferably, the compensation lever is pivotably mounted at a laterally spaced location from the actuator tappet. The compensation lever can thus be mounted on one side, whereby the lever effect can be adjusted by the distance between the connection of the compensation spring and the support of the compensation lever and the distance between the connection of the actuator tappet or the master piston and the support of the compensation lever. It is also possible for a first lever element connected to the compensation spring to be mounted on the support, while a second lever element connected to the actuator tappet or the master piston is mounted on the support, whereby the first lever element and the second lever element are connected to one another via a common bearing shaft mounted in the support. In this case, the compensation lever is formed by the first lever element, the second lever element, and the bearing shaft.The first lever element and the second lever element can thus be arranged in particular at an angle different from 180° to one another and / or substantially parallel to one another, for example in order to design the compensation lever as an angle lever and to form a space-saving arrangement.

[0011] Particularly preferably, the compensation lever is mounted on the actuator tappet or the master piston so that it can be displaced and rotated along its longitudinal extent. The actuator tappet can, for example, be extended out of the actuator or retracted into the actuator in a substantially tangential direction relative to a rotational axis of the compensation lever. During the stroke movement of the actuator tappet, the distance between the connection of the compensation lever to the actuator tappet or to the master piston and the rotational axis can change. However, the compensation lever can be displaced along its longitudinal direction on the actuator tappet or on the master piston so that the stroke movement of the actuator tappet cannot be blocked by the compensation lever. For this purpose, the compensation lever or at least the second lever element of the compensation lever can be mounted on the actuator tappet or on the master piston so that it can be displaced along its longitudinal extent.However, along the longitudinal extension of the actuator tappet, the compensation lever strikes the actuator tappet or the master piston, so that a force component of the compensation spring can act on the actuator tappet or the master piston via the compensation lever in the longitudinal direction of the actuator tappet, influencing the actuating force on the master cylinder. Furthermore, this can change the effective lever arm between the rotational axis of the compensation lever and the actuator tappet or the master piston, which can result in a non-linear characteristic curve of the spring force of the compensation spring acting on the actuator tappet or the master piston.This allows the spring force of the compensation spring acting on the actuator tappet or on the master piston to be deliberately adjusted via the stroke of the actuator tappet in order to achieve a specific characteristic curve of the actuating force depending on the stroke of the actuator tappet.

[0012] In particular, the compensation spring and the actuator are mounted on a common mounting plate. The mounting plate can, for example, be part of a clutch bell housing, which, as a motion-resistant component, covers at least part of the clutch. The actuator can thus be installed as a single mounting unit with the compensation spring. Furthermore, the characteristic curve of the actuating force provided by the actuator and the compensation spring as a function of the actuator plunger's stroke can be verified before installing the actuator.

[0013] Preferably, the compensation spring is preloaded in a minimally extended position of the actuator plunger. This allows the compensation spring to provide a spring force right at the beginning of the actuator plunger's stroke.

[0014] Particularly preferably, the compensation spring exerts a spring force in the direction of an extension direction of the actuator plunger and / or opposite to the extension direction of the actuator plunger between a minimally extended position of the actuator plunger and a maximally extended position of the actuator plunger in order to adjust a characteristic curve of the actuating force acting on the master cylinder. In particular, the force direction of the compensation spring can change between the minimally extended position of the actuator plunger and the maximally extended position of the actuator plunger between the extension direction and the opposite direction. Depending on the application, the compensation spring can merely shift the level of the actuating force on the master cylinder upwards or downwards and / or, through a corresponding characteristic curve, even out the required actuating force by mitigating pressure peaks.

[0015] The invention further relates to a clutch system for a drive train of a motor vehicle, comprising a clutch, in particular a friction clutch, for coupling a drive shaft of a motor vehicle engine to a transmission input shaft of a motor vehicle transmission, and an actuating device, which can be designed and developed as described above, for actuating the clutch. The simple replacement of the easily accessible compensation spring provided outside the clutch and the actuator enables cost-effective adaptation of clutch systems to different load conditions of different drive trains.

[0016] In particular, the clutch has a return spring for setting the clutch to a defined initial position, wherein the return spring preloads the compensation spring at least partially, in particular substantially completely, in the initial position. The compensation spring can thus be preloaded indirectly by the return spring via the hydraulic path, without requiring the actuator to be operated counter to the extension direction of the actuator plunger. Part of the spring force exerted by the return spring in the initial position can be compensated by the compensation spring, so that a correspondingly lower actuator force is required from the actuator to move the clutch out of the initial position.

[0017] Preferably, the clutch is open in the defined initial position to interrupt the flow of torque or closed to transmit torque. The clutch can thus be configured as "normally open" or "normally closed." The actuating device can be used for a pulled and / or a pushed-in friction clutch. The force curve of the actuating force can be suitably adjusted using the compensation spring.

[0018] The invention will be explained below by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below can represent an aspect of the invention both individually and in combination. They show: Fig. 1: a schematic perspective view of an actuating device, Fig. 2: a schematic diagram of a first embodiment of a clutch system in an unactuated position, Fig. 3: a schematic diagram of the coupling system from Fig. 2 in an actuated position, Fig. 4: a schematic diagram of the clutch system of Fig. 2 and Fig. 3 occurring forces, Fig. 5: a schematic diagram of a second embodiment of a clutch system in an unactuated position, Fig. 6: a schematic diagram of the coupling system from Fig. 5 in an actuated position and Fig. 7: a schematic diagram of the clutch system of Fig. 5 and Fig. 6 occurring forces.

[0019] The Fig. The actuating device 10 shown in Figure 1 comprises an actuator 12 with an extendable actuator plunger 14, which can act on a master piston 18 of a master cylinder 20 via a joint 16. The master cylinder 20 is part of a hydraulic line 22, in which the master cylinder 20 is hydraulically connected to a slave cylinder 26 via a hydraulic line 24. The slave cylinder 26 can extend an annular slave piston 28 in order to displace a pressure plate of a friction clutch, for example via a pivotable lever spring, whereby a drive shaft of a motor vehicle engine can be coupled to a transmission input shaft of a motor vehicle transmission in a drive train of a motor vehicle. A compensation tank 30 is connected to the hydraulic line 22 in order to absorb hydraulic oil displaced from the hydraulic line 22 and to add required hydraulic oil.In addition, a compensation spring 32 is provided outside the actuator 12, which acts on the actuator tappet 14 and / or the master piston 18 via a compensation lever 34 in order to adjust an actuating force acting on the master cylinder 20.

[0020] In the Fig. 2 and Fig. 3 illustrated clutch system 36 actuates the actuating device 10 from Fig. 1 shows a friction clutch 38 that is configured as "normally open" and is open when no actuating force is applied. The friction clutch 38 has an actuating element 40, which is designed, for example, as a pivotable lever spring configured as a disc spring, wherein the pivoting of the lever spring is achieved by changing the conicity of the disc spring. The pivoting of the actuating element 40 can displace a pressure plate 42 in order to frictionally press a clutch disc 44 between the pressure plate 42 and a counterplate 46, whereby a torque can be transmitted between the drive shaft and the transmission input shaft.A return spring 48, which is supported, for example, on the counter-plate 46 and is designed in particular as a leaf spring, engages the pressure plate 42 and can automatically move the pressure plate 42 into an initial position corresponding to the open position of the friction clutch 38 if no actuating force is introduced from the actuating system 10 via the actuating element 40.

[0021] In the illustrated embodiment, the compensation spring 32 and the cantilevered compensation lever 34 are arranged relative to one another in such a way that when the actuator plunger 14 is extended from the actuator 12, the pre-tensioned compensation spring 32 initially acts on the master cylinder 26 with a force component opposite to the extension direction of the actuator plunger 14 and, later in the stroke movement of the actuator plunger 14, in the direction of the extension direction of the actuator plunger 14. The connection of the compensation spring 32 to the compensation lever 34 is pivoted between the extreme positions of the actuator plunger 14 in such a way that the portion of the force direction of the compensation spring 32 running in the longitudinal direction of the actuator plunger 14 is reversed. As in Fig. 4, in which a force 50 is plotted over a stroke 52, a compensation spring characteristic curve 54 of the compensation spring 32 changes from a positive value opposite to the extension direction of the actuator plunger 14 to a negative value in the direction of the extension direction of the actuator plunger 14. A clutch characteristic curve 56 to be applied by the actuating device 10 increases sharply towards the end of the stroke 52 due to the spring force of the return spring 48 that has to be overcome and the required contact pressure that has to be applied in the friction clutch 38 and even exceeds a maximum possible actuator force 58. The maximum possible actuator force 58 is, however, high enough to be able to compress the compensation spring 32 at the beginning of the stroke 52.After the change in the spring force that can be applied by the compensation spring 32 in the direction of the extension direction of the actuator tappet 14, an actuator force curve 60 of the actuator 12 and a negated compensation spring characteristic curve 62 of the compensation spring 32 can add up to an actuating force acting on the master cylinder 26 or the master piston 28 of the master cylinder 26, which is large enough to be able to map the clutch characteristic curve 56 even at the end of the stroke 52 of the actuator tappet 14.

[0022] In the Fig. 5 and Fig. 6 illustrated clutch system 36 actuates the actuating device 10 from Fig. 1 compared to that in Fig. 2 and Fig. 3, the clutch system 36 comprises a friction clutch 38 which is designed as "normally closed" and is closed when the actuating force is not applied. Furthermore, the compensation spring 32 is fastened together with the actuator 12 to a common mounting plate 64. The spring force of the compensation spring 32 essentially only points in the direction of the extension direction of the actuator plunger 14. The spring force of the pre-tensioned compensation spring 32 and the actuator force of the actuator 12 can thus add up to a common actuating force, whereby a force level of the clutch characteristic curve 56 that lies above the maximum possible actuator force 58 can be achieved, as shown in Fig. 7 shown. List of reference symbols 10 Actuating device 12 Actuator 14 actuator tappets 16 joint 18 master pistons 20 master cylinders 22 hydraulic line 24 Hydraulic line 26 slave cylinders 28 slave pistons 30 expansion tanks 32 Compensation spring 34 compensation levers 36 Coupling system 38 Friction clutch 40 Actuating element 42 Pressure plate 44 Clutch disc 46 Counter plate 48 Return spring 50 power 52 stroke 54 Compensation spring characteristic curve 56 Clutch characteristic curve 58 maximum possible actuator force 60 Actuator force curve 62 negated compensation spring characteristic curve 64 mounting plate

Claims

[1] Actuating device for actuating a clutch (38) for coupling a drive shaft of a motor vehicle engine with a transmission input shaft of a motor vehicle transmission, with an actuator (12) for triggering an actuation of the clutch (38), wherein the actuator (12) has an extendable actuator plunger (14), a master cylinder (20) which can be actuated directly or indirectly by the actuator tappet (14) for imposing a pressure change in a pressure chamber connected to the master cylinder (20) hydraulic line (24) connected to the displacement of an actuating element (40) of the clutch (38) and a compensation spring (32) provided outside the actuator (12) for increasing a maximum actuating force that can be exerted by the actuator tappet (14) on the master cylinder (20). [2] Actuating device according to claim 1 characterized bythat the compensation spring (32) acts on the actuator tappet (14) and / or on a master piston (18) of the master cylinder (20) via a compensation lever (34), wherein an angular position of the compensation lever (34) is dependent on a displacement of the actuator tappet (14) in the actuator (12). [3] Actuating device according to claim 2 characterized by that the compensation lever (34) is pivotally mounted at a laterally spaced distance from the actuator tappet (14). [4] Actuating device according to claim 2 or 3 characterized by that the compensation lever (34) is rotatably mounted on the actuator tappet (14) or the master piston (18) so as to be displaceable along its longitudinal extent. [5] Actuating device according to one of claims 1 to 4 characterized by that the compensation spring (32) and the actuator (12) are fastened to a common mounting plate (64). [6] Actuating device according to one of claims 1 to 5 characterized bythat the compensation spring (32) is pre-tensioned in a minimally extended position of the actuator plunger (14). [7] Actuating device according to one of claims 1 to 6 characterized by that the compensation spring (32) exerts a spring force in the direction of an extension direction of the actuator tappet (14) and / or counter to the extension direction of the actuator tappet (14) between a minimally extended position of the actuator tappet (14) and a maximally extended position of the actuator tappet (14) for setting a characteristic curve of the actuating force acting on the master cylinder (20). [8] Clutch system for a drive train of a motor vehicle, with a clutch (38), in particular a friction clutch (38), for coupling a drive shaft of a motor vehicle engine to a transmission input shaft of a motor vehicle transmission and an actuating device (10) according to one of claims 1 to 7 for actuating the clutch (38). [9] Coupling system according to claim 8 characterized by that the clutch (38) has a return spring (48) for setting the clutch (38) into a defined starting position, wherein the return spring (48) prestresses the compensation spring (32) at least partially, in particular substantially completely, in the starting position. [10] Coupling system according to claim 8 or 9 characterized by that the clutch (38) is open in the defined initial position to interrupt a torque flow or closed to transmit torque.

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