GB2328993A

GB2328993A - Clutch control unit which controls clutch torque in dependence on engine torque

Info

Publication number: GB2328993A
Application number: GB9811739A
Authority: GB
Inventors: Michael Salecker
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1997-06-04
Filing date: 1998-06-02
Publication date: 1999-03-10
Anticipated expiration: 2018-06-02
Also published as: GB2328993B; GB9811739D0; DE19823766A1; FR2764247A1; DE19823766B4; FR2764247B1

Abstract

A clutch control unit 13a controls a torque transferable by clutch 3 in dependence on an engine torque produced by engine 2. The clutch torque is regulated within a predefined tolerance band around the engine torque and the tolerance band is dependent on a gear transmission ratio set in gearbox 4 by a shift lever 18. Sensors 19a. 19b detect the ratio and/or shift intent and outputs this information to control unit 13a which also receives signals from other sensors, eg throttle valve sensor 15, speed senor 15, tacho sensor 17 etc. The clutch torque Mkuppl is proportional to the engine torque Mmotor over a proportionality factor k and/or a summand B so that the clutch torque Mkuppl is greater than the engine torque Mmotor Proportionality factor k and/or the summand B may vary according to the gear ratio selected, for example k could be greater in a higher than in a lower gear so that the clutch torque in first gear may be in a range of 1.02 and 1.25 times the engine torque. Gearbox 4 may be an automatic gearbox of, for example, a planetaary type or of a CVT variety.

Description

2328993 DEVICE FOR CONTROLLING A TORQUE TRANSFERABLE BY A CLUTCH The

invention relates to a device and method for controlling the torque transferable by an automated clutch in the drive train of a motor vehicle with an engine and gearbox with a shift element for selecting the gear transmission ratio and a sensor for detecting the gear transmission ratio, the engine provides on the output side an ensuing engine torque, with an operating unit, such as an actor controllable by a control unit for controlling the torque transferable by the clutch.

Devices of this kind are known from DE-OS 195 04 847. With devices of this kind a so-called torque matching is advantageous, that is a control of the torque transferable by the clutch proportional to the ensuing engine torque or within a tolerance band around the ensuing engine torque, since the operation, engagement or disengagement of the clutch can take place very quickly in the case of such a clutch and thus the reaction times can be reduced.

By adjusting the clutch torque proportional to the engine torque or within a tolerance band around the engine torque it is possible to obtain a clear improvement in the load change behaviour. This improvement of the load change behaviour can be reached through short-term slip phases which occur on the clutch.

An object of the present invention is to provide a device of the above kind and a method for same which in permanent operation only experiences a slightly increased load in respect of the actor. Furthermore a device of the above kind is to be provided which improves the devices according to the prior art and which at the same time ensures a high operating reliability.

2 This is achieved with a device according to the invention in that the control unit controls the torque transferable by the clutch in dependence on the ensuing engine torque wherein the clutch torque is controlled within a predefinable tolerance band around the ensuing engine torque and the tolerance band is dependent on the gear transmission ratio.

Since the vibration amplitude of the jolting vibration in the event of vibrations caused by jumps in the engine torque depends on the stiffness and damping reduced on the excited side the jolting vibrations are dependent on the gear. Through the gear-dependent torque matching or the gear-dependent over-pressing of the clutch, such as the tolerance band which is selected dependent on gear, it is possible to achieve increased comfort.

It is advantageous if the width of the tolerance band is dependent on gear. It is particularly expedient if the torque transferable by the clutch is proportional to the engine torque through a proportionality factor k and/or a summand B. Thus the torque Mkuppl transferable by the clutch could be controlled as follows:

Mkuppl k Mmotor + B' It is further advantageous if the torque transferable by the clutch is greater by a predefinable amount than the ensuing engine torque.

It is likewise expedient if the tolerance band is greater in a higher gear than in a lower gear. It is likewise expedient if a proportionality factor and/or a summand is greater in a higher gear than in a lower gear. It can thereby also be advantageous if the width of the tolerance band is the same in individual gears and is a different size in other gears. This is expedient particularly in those gears in which the vehicle has a particular tendency to vibrations in the drive train.

It is particularly advantageous if the transferable torque is in f irst gear in the area of 1. 02 and 1. 25 times the ensuing engine torque. Furthermore it is expedient if the transferable torque is in the highest gear in the range from 1.5 and 2.5 times the ensuing engine torque. The intermediate gears between the lowest gear and highest gear are preferably selected stepped. Individual gears can thereby also have the same values of the tolerance band or proportionality factors.

According to a further idea according to the invention it is expedient if the maximum rise per time unit of the torque transferable by the clutch is selected as a function of the gear transmission ratio.

It is likewise advantageous if the maximum rise per unit time of the torque transferable by the clutch is less in a lower gear than in a higher gear.

According to a further idea according to the invention it can be advantageous with a method for controlling such as controlling or regulating an automated clutch if a device of the above kind is used.

The invention will now be explained by way of example with reference to the drawings in which:

Figure 1 is a diagrammatic illustration of a vehicle; 1 Figure 2 is a block diagram; and Figure 3 is a diagram.

Figure 1 shows diagrammatically a vehicle 1 with a drive unit 2 such as an engine or internal combustion engine. Furthermore an automatically operated clutch 3 and gearbox 4 are shown in the drive train of the vehicle. In this embodiment the clutch is mounted in the force flow between the engine and gearbox wherein a drive torque of the engine is transferred through the clutch to the gearbox and f rom the gearbox 4 on the output side to an output shaft 5 and to an axis 6 and wheels 6a on the output side.

The clutch 3 is designed as a friction clutch, multi-plate clutch, magnetic powder clutch or converter bridging clutch wherein the clutch can be a self-adjusting, wearcompensating clutch. The gearbox 4 is shown as a manual shift gearbox such as a step change gearbox. According to the idea according to the invention the gearbox can however also be an automated shift transmission which can be shifted automatically by means of at least one actor. By automated shift trAnsmission is meant also an automated gearbox which is shifted with a break in the pulling power and the shift process of the- gear transmission ratio is carried out controlled by means of at least one actor.

Furthermore an automated gearbox can also be used wherein an automatic gearbox is a gearbox substantially without break in the pulling force during the shift processes and which as a rule is comprised of planetary gear stages.

Furthermore an infinitely adjustable gearbox, such as for example cone pulley belt contact gearbox can be used. The automatic gearbox can also be formed with a clutch 3, such as a friction clutch, mounted on the output side. The clutch can furthermore be formed as a starting clutch and/or turning set clutch for reversing the direction of rotation and/or safety clutch with a deliberately controllable transferable torque. The clutch can be a dry friction clutch or a wet running friction clutch which runs f or example in a f luid. It can also be a torque converter.

The clutch 3 has a drive side 7 and an output side 8 wherein a torque is transferred f rom the drive side 7 to the output side 8 by the clutch disc 3a being force-biased by means of the pressure plate 3b, plate spring 3c and disengagement bearing 3e as well as the flywheel 3d. For this biasing the disengagement lever 20 is operated by means of an operating device such as actor.

The control of the clutch 3 is carried out by means of a control unit 13 such as a control apparatus which can comprise the control electronics 13a and an operating unit such as an actor 13b. In another advantageous design the actor and control electronics can also be mounted in two different structural units such as housings.

The control unit 13 can contain the control and power electronics for controlling the electric motor 12 of the actor 13b. It can thereby be reached for example that the system requires as a single structural space the structural space for the actor with electronics. The actor consists of a drive motor 12, such as electric motor, wherein the electric motor 12 acts on the master cylinder 11 through a gearbox such as a worm gear or spur wheel gear or crank gear or threaded spindle gear. This action on the master cylinder can take place directly or through a rod linkage.

SP2163. P3 01106/98 6 The movement of the output part of the actor, such as master cylinder piston 11a is detected with a clutch path sensor 14 which detects the position or setting or speed or acceleration of a value which is proportional to the position or engagement position respectively of the speed or acceleration of the clutch. The master cylinder 11 is connected to the slave cylinder 10 through a pressurised medium pipe 9 such as hydraulic pipe. The output element loa of the slave cylinder is in active connection with the disengagement lever or disengagement means 20 so that a movement of the output part 10a of the slave cylinder 10 causes the disengagement means 20 to be likewise moved or tilted in order to control the torque transferable by the clutch 3.

The actor 13b for controlling the transferable torque of the clutch 3 can be operated by pressurised medium, i.e. it can be equipped with pressurised medium master and slave cylinders. The pressurised medium can be for example a hydraulic fluid or a pneumatic medium. The operation of the pressurised medium master cylinder can be provided by an electric motor wherein the electric motor 12 can be controlled electronically. The drive element of the actor 13b can also be apart from an electric motor drive element any other type of drive element for example operated by pressurised medium.

Furthermore magnetic actors can also be used to set the position of an element.

In the case of a friction clutch the control of the transferable torque is carried out in that the contact pressure of the friction linings of the clutch disc takes place deliberately between the flywheel 3d and pressure plate 3b. Through the position of the disengagement means 35 20, such as disengagement fork or central disengagement 7 - member it is possible to deliberately control the force biasing of the pressure plate or friction linings respectively whereby the pressure plate can thereby be moved between two end positions and set and fixed anywhere between same. one end position corresponds to a fully engaged clutch position and the other end position to a fully disengaged clutch position. In order to control a transferable torque which is less for example than the engine torque momentarily arising, it is possible to control for example a position of the pressure plate 3b which lies in an intermediate area between the two end positions. The clutch can be fixed in this position by means of the deliberate control of the disengagement means 20. Transferable clutch torques can however also be controlled which lie defined above the engine torques momentarily arising. In such a case the engine torques actually arising can be transferred whereby the torque irregularities in the drive train in the form of for example torque peaks can be damped and/or insulated.

Furthermore to control such as steer or regulate the torque transferable by the clutch, sensors are used which monitor at least at times the relevant values of the overall system and which supply the condition values, signals and measured values which are necessary for control and which are processed by the control unit whereby a signal connection can be provided or exist with other electronics units, such as for example engine electronics or an electronics of an anti-lock braking system (ABS) or an anti-slip regulating system (ASR). The sensors detect for example speeds, such as wheel speeds, engine speeds, the position of the load lever, the throttle valve position, the gear position of the gearbox, a shift intent and further characteristic values specific to the vehicle. The actual or ensuing engine torque can be detected or calculated. Furthermore this ensuing engine torque can be provided by an engine control through a data bus.

Figure 1 shows that a throttle valve sensor 15, an engine speed sensor 16, as well as a tacho sensor 17 are used and supply measured values and information to the control apparatus. The electronics unit, such as computer unit of the control unit 13a processes the system input values and 10 sends control signals to the actor 13b.

The gearbox is formed as a step change gearbox wherein the transmission ratio stages are changed by a shift lever or the gearbox is operated or controlled by this shift lever. Furthermore at least one sensor 19b is mounted on the service lever such as shift lever 18 of the manual shift gear to detect the shift intent and/or gear position and forward same to the control apparatus. The sensor 19a is attached to the gearbox and detects the actual gear position and/or shift intent. The shift intent recognition using at least one of the two sensors 19a, 19b can take place in that the sensor is a force sensor which detects the force acting on the shift lever. Furthermore the sensor can however also be formed as a path or position sensor wherein the control unit detects the shift intent from the time change of the position signal.

The control unit is in signal connection at least at times with all the sensors and evaluates the sensor signals and system input values in the manner and way where the control unit sends control or regulating commands to the at least one actor in dependence on the actual operating point. The drive element 12 of the actor such as electric motor receives from the control unit which controls the clutch operation a setting value in dependence on measured values and/or system input values and/or signals of the attached sensor unit. To this end a control program is implemented in the control device as hard and/or software which evaluates the incoming signals and calculates or determines the output values from comparisons and/or functions and/or characteristic fields.

a The control device 13 advantageously has an implemented torque determining unit, a gear position determining unit, slip determining unit and/or an operating state determining unit or is in signal connection with at least one of these units. These units can be implemented by control programs as hardware and/or as software so that by means of the incoming sensor signals the torque of the drive unit 2 of the vehicle 1, the gear position of the gearbox 4 as well as the slip which prevails in the clutch and the actual operating state of the vehicle can be determined. The gear position determining unit detects from the signals of the sensors 19a and 19b the gear actually engaged. The sensors are thereby attached on the shift lever and/or on the setting means inside the gearbox, such as for example a central shift shaft or shift rod and these detect for example the position and/or the speed of these component parts. Furthermore a load lever sensor 31 can be mounted on the load lever 30 such as accelerator pedal which detects the load lever position. A further sensor 32 can function as an idling switch i.e. with an activated accelerator pedal, such as load lever this idling switch 32 is switched on and when a signal is not activated it is switched off so that through this digital information it is possible to detect whether the load lever such as accelerator pedal is activated. The load lever sensor 31 detects the degree of operation of the load lever.

- 10 Figure 1 shows in addition to the accelerator pedal 30 such as load lever and the sensors connected therewith a brake operating element 40 for operating the operating brake or the parking brake, such as brake pedal, hand brake lever or hand or foot operated operating element of the parking brake. At least one sensor is mounted on the operating element 40 and monitors its activation. The sensor 41 is for example formed as a digital sensor, such as switch wherein this detects that the operating element is activated or not activated. A signal device such as a brake light can be in signal connection with this sensor which signals that the brake is operated. This can take place both for the operating brake and for the parking brake. The sensor can however also be formed as an analogue sensor wherein a sensor of this kind such as for example a potentiometer determines the degree of operation of the operating element. This sensor can also be in signal connection with a signal device.

Figure 2 shows a block circuit diagram for illustrating the invention. The control process is started in block 101. In block 102 it is asked whether the f irst gear is engaged. If this is not the case then in block 103 it is asked whether the second gear is engaged. If this is not the case it is assumed that one of the gears 3 to 5 or 6 is engaged, neutral is not engaged and a driving situation exists. In this case in block 104 the factor k is selected at k = 1. 75. If however f irst gear is engaged, then at 105 k is selected at k = 1.05. If second gear is engaged then at 106 k is selected at k = 1.25.

Then at 107 the torque Mk,ppl transferable by the clutch is selected at MkuPP1 = (k A) M,,.,, before at 108 the process is terminated. A gear-dependent torque-matching thus exists. The value A determines the width of the tolerance band. It can lie in the range from 0. 05 to 1 wherein the width A can also be dependent on gear. A summand B can likewise be added to the term on the right hand side of the equation. This equation provides the ideal clutch torque which is to be controlled.

Instead of the torque transferable by the clutch, the maximum time rise or gradient dMkuppl/dt can likewise be selected dependent on gear, thus only block 107 is to be completed or modified accordingly. The equation in block 107 can read for example as follows:

dMkuppl/dt = K Mkuppl-max + C Figure 3 shows a diagram illustrating the engine torque M.O,., 201 and the torque Mkupp, transferable by the clutch at 203 as well as the tolerance band shown with the lower limit 202a and the upper limit 202b as a function of the time t. The engine torque 201 thus rises monotonously.

The tolerance band with the lower limit and the upper limit substantially follows this engine torque. The controlled torque transferable by the clutch lies within this tolerance band. For t < to first gear is engaged for example. For t > to third gear is engaged for example.

From to the value of the upper limit of the tolerance band 204 rises to a higher value and the torque transferable by the clutch follows this increase in the limit in controlled manner. The difference 205 between the lower limit and upper limit can be used as a width of the tolerance band.

12 - It is particularly expedient if the upper limit and lower limit deviate from the engine torque by a variable amount.

The patent claims filed with the application are proposed wordings without prejudice for obtaining wider patent protection. The applicant retains the right to claim further features disclosed up until now only in the description and/or drawings.

References used in the sub-claims refer to further designs of the subject of the main claim through the features of each relevant sub-claim; they are not to be regarded as dispensing with obtaining an independent subject protection for the features of the sub-claims referred to.

is The subjects of these sub-claims however also form independent inventions which have a design independent of the subjects of the preceding claims.

The invention is also not restricted to the embodiments of the description. Rather numerous amendments and modifications are possible within the scope of the invention, particularly those variations, elements and combinations and/or materials which are inventive for example through combination or modification of individual features or elements or process steps contained in the drawings and described in connection with the general description and embodiments and claims and which through combinable features lead to a new subject or to new process steps or sequence of process steps insofar as these refer to manufacturing, test and work processes.

- 13

Claims

1. Device for controlling the torque transferable by an automated clutch in the drive train of a vehicle with an engine and gearbox with a shift element for selecting the gear transmission ratio and a sensor for detecting the gear transmission ratio, the engine provides on the output side a controllable instantaneous engine torque, with an operating unit, such as an actor, controllable by a control unit for controlling the torque transferable by the clutch, characterised in that the control unit controls the torque transferable by the clutch in dependence on the engine torque wherein the clutch torque is controlled within a predefinable tolerance band around the instantaneous engine torque and the tolerance band is dependent on the gear transmission ratio.

2. Device according to claim 1 characterised in that the width of the tolerance band is dependent on gear.

3. Device according to claim 1 characterised in that the torque transferable by the clutch is proportional to the engine torque over a proportionality factor and/or a summand.

4. Device according to claim 1 characterised in that the torque transferable by the clutch is greater by a predefinable amount than the ensuing engine torque.

5. Device according to claim 1 characterised in that the tolerance band is greater in a higher gear than in a lower gear.

6. Device according to one of the claims 3, characterised in that the proportionality factor and/or the summand is greater in a higher gear than in a lower gear.

is

7. Device according to one of the preceding claims, characterised in that the transferable torque is in first gear in the range of 1.02 and 1.25 times the ensuing engine torque.

8. Device according to one of the preceding claims, characterised in that the transferable torque is in the highest gear in the range of 1.5 and 2. 5 times the ensuing engine torque.

9. Device more particularly according to one of the preceding claims, characterised in that the maximum rise per unit time of the torque transferable by the clutch is selected as a function of the gear transmission ratio.

10. Device according to claim 9 characterised in that the maximum rise per unit time of the torque transferable by the clutch is less in a lower gear than in a higher gear.

11. Method for controlling or regulating the torque transferable by an automated clutch, more particularly by means of a device according to one of the preceding claims.

12. Device for controlling the torque transferable by an automated clutch in the drive train of a vehicle substantially as herein described with reference to the accompanying drawings.

- is -

13. A method for controlling or regulating the torque transferable by an automated clutch substantially as herein described with reference to the accompanying drawings.