HK1069361A - Drive train - Google Patents

Description

Power transmission system

Technical Field

The invention relates to a drivetrain having a friction clutch arranged in a power path between an internal combustion engine and a transmission, the friction clutch having an input part connected to the internal combustion engine and at least one output part connected to a transmission input shaft of the transmission, and a release device for the clutch.

Background

The friction clutch is actuated in a manner known per se by means of a hydraulic release system which consists of a manually or automatically actuated actuating cylinder and an output cylinder of the release clutch, the two cylinders being connected by a hydraulic line. In so-called positive-pressure clutches, the clutch is disengaged in the state of no force application of the clutch, and the frictional engagement for connecting the internal combustion engine to the transmission is achieved by the delivery cylinder being actuated under pressure and holding the output cylinder. In particular with double clutches, in which a common input member is branched into two output members each having a transmission input shaft, it is advantageous to arrange the clutches in this way. If one of the two or two release devices fails, for example due to loss of pressure medium, the clutches are continuously opened and the transmission is not locked, as is the case with clutches which are normally closed in the force-free state.

Friction clutches of the type mentioned above are usually used in automatic transmissions (ASG) or dual clutch transmissions (PSG) in addition to manual transmissions, and are usually controlled by a control unit, in which the engagement and disengagement of the clutches and gears are automatically actuated. If such a control device fails, it can happen according to the control strategy used: the clutch position of one clutch or of both clutches in a dual clutch transmission is "frozen", so that the operation of the internal combustion engine can no longer be controlled in dependence on the transmission output speed and thus on the wheel speed, i.e. for example, the operation of the internal combustion engine is no longer possible for maintaining the auxiliary group when the motor vehicle is stationary.

Disclosure of Invention

The object of the present invention is therefore to provide a drivetrain which can disengage a clutch which is no longer open in the event of a failure of the transmission control. This task should be simple to implement, cost-effective and easy to install. As few new parts as possible should be used. Furthermore, it should be avoided: when the transmission control device fails, the driver must undergo unusual operation in order to avoid interference with the driving conditions.

This task will be achieved by: a powertrain having a friction clutch in an energy path between an internal combustion engine and a transmission, the friction clutch having: an input component, at least one output component which can be disconnected with the input component and at least one separation device; wherein the at least one output part is decoupled from the input part in the force-free state and is in frictional engagement with the input part by means of the at least one decoupling device, and the at least one decoupling device is formed by a delivery cylinder and an output cylinder which is functionally connected to the delivery cylinder via a hydraulic line, and a pressure relief device is provided in the hydraulic line between the delivery cylinder and the output cylinder, which device, when actuated from the outside, restores the pressure exerted between the delivery cylinder and the output cylinder.

The concept according to the invention is particularly advantageous for a double clutch in which a ring element, which is connected in a rotationally fixed manner to the input element, is actuated by a release device, the output element being frictionally coupled to the input element, and at least one release device having the pressure relief device. It will be appreciated that it is advantageous for both separating devices to have a pressure relief device.

The external actuation is that the driver can influence the disengagement state of the two clutches when the control of the transmission and the automatic clutch fails, when he actuates the actuating device for actuating the pressure relief device. It is particularly advantageous here that, in the case of a dual clutch, the two pressure reduction devices can be operated by means of a single operating device. It is also advantageous if the driver actuates the actuating device in dependence on a habit. For example, the actuation of the pressure relief device can be combined with an actuation of a selector lever for selecting a motor vehicle operating program, for example for selecting a transmission drive stage or for setting a parking brake position, wherein the actuation of the pressure relief device takes place as a function of the selector lever position. The depressurisation means can be operated, for example, in the selection position "neutral" or "parking brake"; in the forward or reverse driving position, the operation of the pressure reducing device is stopped when a manual operating program is predefined, in which the driving range or gear is shifted up or down by the movement of the selector lever.

The transmission of the signal from the operating device to the pressure reduction device can be mechanical, for example by means of flexible shafts or tie rods; hydraulically, for example by means of a delivery/output cylinder arrangement; or electrically (by means of electrical lines), for example by means of at least one switch arranged on the operating device, which is connected to a solenoid valve on the pressure-reducing device. It is understood that these functional connection means may also be formed in combination or in another way.

In one embodiment, the pressure-reducing device advantageously has an inlet from the inlet side of the delivery cylinder and an outlet to the outlet side of the delivery cylinder. Between which a chamber with a desirably negligible dead volume is arranged, which can be enlarged by means of an axially movable piston in dependence on the pressure prevailing in the hydraulic line. It will be appreciated that the piston is sealed against the chamber by sealing means, for example sealing rings such as O-rings or groove rings, as is known from delivery and output cylinders. The axial movement of the piston is prevented by a fixing device as long as the pressure-reducing device should not be operated. The securing device is in operative contact with the functional connection of the actuating device, for example a pin can be provided on the flexible shaft, which pin is inserted radially in relation to the piston axis and is inserted into the piston by the movement of the flexible shaft. Alternatively or additionally, the piston can be fixed by other means, such as electrical means, for example an electromagnet or a piezo element.

The two pressure relief devices can advantageously be mounted in a housing and/or combined in the housing of a delivery cylinder or delivery cylinder. In a particularly advantageous manner, the pressure relief device can be combined in a structural unit consisting of an electric actuator, such as an electric motor or a piezoelectric element, a transmission for converting the rotation of the electric motor into a translational movement of the transmission cylinder, and the transmission cylinder, wherein the entire combination of two such structural units for actuating the two clutches can also be advantageous, for example, as a result of which the installation space and the housing parts can be saved.

In a further preferred embodiment, the operating device operates the pressure relief device by means of a functional device in such a way that: when the functional connection is switched on without current, the pressure relief device is operated, i.e. according to the present expression the pressure relief device can achieve a pressure equalization in the hydraulic line. The main advantage of this is that the pressure relief device can still fulfil its function and open the clutch in the event of a simultaneous failure of the control device and the operating device, for example due to a total failure of the power supply. For this purpose, the pressure reduction device can be formed directly using solenoid valves or piezoelectric elements, for example, by reducing the pressure in the pressure medium line by moving a slide or piston.

In addition, the use of an electrically operated pressure reducing device has the advantage that, in particular, the release of the pressure reducing device is avoided when the selector lever is switched back and forth rapidly between the operating sequences "forward" and "reverse", for example when the operating sequence "neutral" is passed during this selection. In this case, or always in the "neutral" operating program, the release can also be delayed. A delay time between 0.1 and 1 second has proved advantageous.

It will be understood that the proposed volume compensation device is also advantageous for a clutch, by means of which auxiliary units, such as air conditioning compressors or electric machines for starting internal combustion engines, auxiliary drives or exclusively driving motor vehicles and/or for generating electrical energy can be coupled into the drive train. In this case, it is advantageous in the case of a dual clutch transmission to provide an auxiliary group which can be decoupled from one of the two transmission input shafts and/or from the crankshaft.

Drawings

The invention will be described in detail below with the aid of the accompanying figures 1 to 4.

The attached drawings are as follows:

FIG. 1 is a schematic diagram of a powertrain system according to the present invention, an

Figures 2 through 4 are examples of a pressure relief device in various operating states.

Detailed Description

Fig. 1 shows a schematic representation of a drivetrain 100 with an internal combustion engine 40 and a downstream transmission 30, which is provided here as a dual clutch transmission with two transmission input shafts 9a, 9 b. In the energy transmission path between the internal combustion engine 40 and the transmission 30, a dual clutch 2 is provided, which has an input part 3, which is connected in a rotationally locked manner to the crankshaft of the internal combustion engine and is usually embodied in a rigid manner as a so-called Flexplate (Flexplate) -as shown in fig. 1-as an axially elastic or as a double high-mass flywheel, and two output parts 4a and 4b, each of which is connected in a rotationally locked manner to a transmission input shaft 9a and 9b as so-called clutch disks having friction linings, which are in frictional engagement with the input part 3. For this purpose, the input part 3 has an axially fixedly mounted pressure plate 10c, which is provided on both sides with friction engagement surfaces, and is connected in a rotationally locking manner to annular disk parts 10a, 10b, which are each provided with a friction engagement surface, for an output part, are axially displaceable and are connected in a rotationally locking manner to the input part 3. By axial displacement of the annular disc members 10a, 10b a frictional engagement with the friction surfaces of the output members 4a, 4b will be established. In the unstressed state, these friction surfaces are spaced apart from the contact plate 10c, for example by leaf springs, in such a way that no frictional engagement occurs, i.e. the two clutches 2a, 2b associated with the output members 4a, 4b are positive-pressure clutches.

The clutches 2a, 2b are each engaged by axial movement of the release levers 4c and 4 d. The levers 4c and 4d are held in this state by the respective clutch actuation device 5a, 5b until clutch disengagement is required. For both clutches, as is known per se, one setting device may be provided each, but it is also possible to apply a common setting device to both clutches. It is understood that other clutch forms and configurations thereof, such as a positive-action clutch, may also be advantageously used within the meaning of the invention.

The two friction clutches 2a, 2b are to be operated by means of separating devices 5a, 5b, which each consist of: a delivery cylinder 6a, 6b, preferably operated in a known manner by means of an electric actuator 21a, 21 b; an output cylinder 8a, 8b, which can preferably be designed as a ring cylinder arranged concentrically around the transmission input shaft 9a, 9b, a cylinder distributed over the circumference around the transmission input shaft or a cylinder arranged essentially parallel to the transmission input shaft via a lever mechanism; and conduits 7a, 7b connecting the output cylinders 8a, 8b with the delivery cylinders 6a, 6 b.

In the conduits 7a, 7b, a pressure relief device 1 is combined, which comprises in one housing a pressure relief device 1a, 1b for each separation device 5a, 5 b. It is understood that the two pressure reduction devices 1a, 1b can also be embodied separately and can be combined, for example, in one component of a separating system, for example in the delivery cylinders 6a, 6b or the delivery cylinders 8a, 8 b. The decompression device 1 can be controlled by a driver from the outside, for example. For this purpose, the driver can use an operating device 11, which in the illustrated embodiment is a selector lever, for selecting the operating program of the motor vehicle with functions such as parking brake P, reverse gear R, neutral gear N, forward gear D and manual key shift (Tipp-Schaltung) +, -.

The operating requirements of the operating device 11 are transmitted to the pressure relief device 1 by means of a functional connection 12, which may be a flexible shaft or an electrical connection, here in the example shown a functional connection acting on two fixing devices 18, which prevent volume equalization and, in the case of operation, enable volume equalization.

The operating principle of the power transmission system 100 shown in fig. 1 is as follows:

the transmission control device 50 controls a transmission actuating device which, depending on the driving situation, disengages or engages a gear in the transmission and for this purpose controls actuators, such as electric motors 21a, 21b, in a coordinated manner in order to actuate the clutches 2a, 2b, so that the drive train 100 can be operated completely automatically or the driver can shift gears by means of the automated clutch 2 by pressing a selector lever in the +, -position. If the cylinders 6a and 6b are in their rest position, i.e. the clutches 2a, 2b are open, the pressure in the separating devices 5a, 5b is equalized with atmospheric pressure by communication with an equalization tank, not shown. A possible pressure drop. When the actuating cylinders 6a, 6b are actuated, the connection to the equalization tank is closed, the pressure in the lines 7a, 7b is increased and the friction clutches 2a, 2b are actuated. In the event of a malfunction of the control device 50 in this case, the actuating cylinders 6a, 6b will remain in their instantaneous position, whereby the clutches 2a, 2b remain in frictional engagement depending on the position of the lever mechanisms 4c, 4 d. To now decouple the internal combustion engine 40 from the transmission 30, the driver actuates the operating device 11 and thus the pressure reducing device 1, so that the pressure built up in the lines 7a, 7b drops and the clutches 2a, 2b open. In a particularly advantageous manner, different positions of the operating device 11 are used as selector lever (Schalthebel) in order to operate the pressure-reducing device. If the decompression device 1 is substantially in the neutral N and parking brake P position, the driver is therefore not forced to make such a decision: that is, the actuating device must be actuated to a certain state, but the volume compensation device 1 is actuated together in those states in which the driver is actuating the selector lever anyway, for example in the parking position or in the neutral driving position.

Fig. 2 shows a pressure reduction device 1a for the separation device 5a of fig. 1 by way of a detailed embodiment. The housing 22 has a connection 13 from the delivery cylinder side and a connection 14 to the delivery cylinder side and is mounted in the hydraulic line 7 a. Between the two connections 13, 14, a chamber 15 is formed with a predetermined, desired minimum dead volume, which is delimited by a piston 16. The piston 16 is received in the other chamber 26 and the two chambers 15, 26 are sealed from each other by a sealing means 20, which may be an annular seal such as a groove ring seal or an O-ring. In the inserted state, the piston 16 is held in its axial position by a fixing device 18, which in the embodiment shown is configured as a pin 18 projecting into the piston, which pin serves as the front end of the flexible shaft 12, said flexible shaft passing through a sleeve 19. The sleeve 19 can have a sealing effect and can also serve as a jacket for receiving the flexible shaft 12. In order to reduce the dead volume of the chamber 15, the piston 16 is loaded with a force which is exerted by an energy accumulator 17, here a helical spring. A bore 27 for pressure equalization is provided in the housing 22. It will be appreciated that other or alternative means of applying force to the piston, such as the orifice 27 may be closed or pressurized, may be provided in order to reduce the dead volume of the chamber 15, with the accumulator 17 being sized or removable accordingly. In a particular embodiment, the opening 27 can be acted upon by a pressure which is provided by the pressure supply, for example by the operating device 11 (fig. 1) by means of a hydraulic switch.

Fig. 2 shows the decompression device 1a in a fixed state. Fig. 3 shows the decompression device 1a in an operating state, in which the flexible shaft 12 is pulled back and the corresponding securing device 18 is thereby disengaged, i.e. the securing device is pulled out of a groove 28 of the piston 16, so that, in the case of a pressure prevailing in the duct 7a, a pressure acting on the piston 16 which is greater than the spring force of the energy accumulator 17 moves the piston 16 and thereby the chamber 15 receives an increase in volume, which results in the clutch 2a (fig. 1) being disengaged.

Fig. 4 shows a state in which the line 7a is pressureless, for example when a delivery cylinder 6a is in a rest position in which the line 7a is connected to the equalization vessel. In this case, the securing device is also released by means of the operating device 11 (fig. 1) via the flexible shaft 12, since, for example, the driver selects the parking brake or neutral position when the control part 50 is functionally active, but in these positions the position of the piston 16 does not change, since it is held in its position by the energy accumulator 17. Whereby the volume of the chamber 15 remains constant. It should be noted that, when the energy accumulator 17 is designed accordingly, in particular by means of the mass of the piston 16 and/or the hysteresis of the sealing device 20, the decompression device 1a can simultaneously act as a so-called peristaltic filter (Kribbelfilter) for damping vibrations in the line 7a, which vibrations are caused by axial vibrations of the internal combustion engine and are transmitted via the clutch.

Claims (21)

1. A drivetrain having a friction clutch for decoupling a transmission from an internal combustion engine, the friction clutch having: an input element, at least one output element which can be decoupled from the input element, and at least one decoupling device, wherein the at least one output element is decoupled from the input element in the force-free state and forms a frictional engagement with the input element by means of the at least one decoupling device, and the at least one decoupling device is formed by a delivery cylinder and an output cylinder which is operatively connected to the delivery cylinder via a hydraulic line, characterized in that: in the hydraulic line between the delivery cylinder and the delivery cylinder, a pressure relief device is provided which, when operated from the outside, reduces the pressure exerted between the delivery cylinder and the delivery cylinder.

2. The powertrain system of claim 1, wherein: the friction clutch is designed as a dual clutch having an input part and having output parts each connected to a transmission input shaft in a rotationally fixed manner, wherein in each case one release device actuates an axially displaceable ring part connected to the input part in a rotationally fixed manner.

3. The powertrain system of claim 2, wherein: the two separation devices are respectively provided with a pressure reducing device.

4. The power transmission system according to one of claims 1 to 3, characterized in that: the pressure reducing device can be operated by the driver by means of an operating device.

5. The power transmission system according to claim 3 or 4, characterized in that: the two pressure reduction devices can be operated by means of a single operating device.

6. The powertrain system according to one of claims 1 to 5, characterized in that: two pressure relief devices for a dual clutch are mounted in a housing.

7. The powertrain system according to one of claims 1 to 6, characterized in that: at least one pressure reduction device is combined in one delivery cylinder or output cylinder.

8. The powertrain system of claim 4, wherein: the operating device is a selector lever operatively connected to the pressure relief device for the driver to adjust the operating program of the transmission.

9. The powertrain system of claim 8, wherein: the pressure relief device is operated in accordance with the position of the selector lever.

10. The powertrain system of claim 9, wherein: the operation of the pressure reduction device is at least in the working sequence: neutral (N) and/or parking brake (P).

11. The powertrain system of claim 9, wherein: at the selection position: in forward (D) or reverse (R) or in a manual operating sequence (+, -), the operation of the pressure reducing device is stopped.

12. The powertrain system according to one of claims 1 to 11, characterized in that: the pressure reducing device has an inlet on the input side and an outlet on the output side and, between them, a chamber with a dead volume which can be enlarged against the action of an energy accumulator by means of an axially movable piston which is sealed off from the chamber, if the pressure prevailing in the pressure line and acting on the piston is greater than the axial force of the energy accumulator acting on the piston and the axial displacement of the piston is released by the functional connection.

13. The power transmission system according to one of claims 8 to 12, characterized in that: the function connecting device is a flexible shaft connected with the operating device.

14. The power transmission system according to one of claims 8 to 12, characterized in that: the functional connection is an electrical functional connection, which is an operating pin that is connected to an electrically operated switch provided on the operating device.

15. The drivetrain of claim 14, wherein: the functional connection device acts on an electrically actuated pin which is connected to a switch provided on the actuating device.

16. The drivetrain of claim 14, wherein: the functional connection acts on an electrically operated valve which is connected to a switch provided on the operating device.

17. The power transmission system according to one of claims 14 to 16, characterized in that: the electrically functional connection is connected to an electric valve which directly forms the pressure reduction device.

18. The powertrain system according to one of claims 14 to 17, wherein: the electrically functional connection operates the voltage reduction device in a currentless state.

19. The power transmission system according to one of claims 9 to 18, characterized in that: when the position of the selector lever moved through the working-program neutral gear (N) is rapidly switched between the working-program forward gear (D) and the reverse gear (R), the operation of the pressure reducing device is not performed.

20. The powertrain system according to one of claims 9 to 19, characterized in that: the operation of the pressure reducing device is delayed for a predetermined delay time after the selection of the operating program neutral (N).

21. The drivetrain of claim 20, wherein: the delay time is in the range between 0.1 and 1 second.