GB2335244A

GB2335244A - A method of testing an automated clutch

Info

Publication number: GB2335244A
Application number: GB9824805A
Authority: GB
Inventors: Thilo Reichel
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1997-11-19
Filing date: 1998-11-13
Publication date: 1999-09-15
Anticipated expiration: 2018-11-13
Also published as: IT1303910B1; BR9804676A; ITMI982496A1; DE19850977A1; GB9824805D0; JPH11241733A; GB2335244B; FR2771173A1; DE19850977B4; FR2771173B1

Abstract

An automated clutch is engaged/disengaged by a slave cylinder 56 operated by a master cylinder 56 which is actuated by an actuator 24 comprising an electric motor 40 driving a worm wheel 42 and crank drive 44. A position sensor 28 detects a rotary position of the electric motor 40 and thereby the position of piston 50 in master cylinder 56. Testing is accomplished by suppling a predetermined current to the motor 40 which results in a sequence of signals from the sensor 28, this sequence of signals is compared with stored ideal values, entered in an electronic control device (26, fig 1), and any deviation is regarded as a fault which is displayed by a fault indicator/display of the control device (26, fig 1) or by a diagnosis device connected to the control device (26, fig 1). In another embodiment, the position of the actuator 24 is associated with the output capacity, eg torque, slip etc, of the clutch and any deviation between a stored capacity and a detected capacity is recorded as a fault in the control device.

Description

2335244 Method for testing an automated clutch device The invention

relates to a method for testing an automated clutch device, more particularly a clutch device mounted in the drive train of a motor vehicle and having a control device containing a microprocessor. an electrically operated actor governed by the control device, a motion transfer device between the actor and operating member of the clutch as well as a path sensor for detecting the position of the operating member.

Automated clutches have gained increasingly more interest in recent times. Such clutches in conjunction with manual shift transmissions lead to considerable improvements in operating comfort. In addition a drop in fuel consumption is achieved since owing to the lower expense connected with a gear change the vehicle is more frequently driven in the most fuel- saving gear. In conjunction with automated manual shift transmissions the comfort of conventional automatic transmissions is achieved with clutches of this kind without this increase in comfort leading to an increased fuel consumption which is generally the case with conventional automatic transmissions.

Automated clutches have indeed reached a high state of development and are extraordinarily reliable. Nevertheless the importance of comfortably monitoring their functional reliaJility during operation and maintenance service in the event of a diagnosis is high.

The object of the invention is to provide a method for testing an automated clutch device of the kind alreadydescribed by means of which faulty functioning can be reliably detected without increased expense.

SP2281.P3 12 November 1998 2 - Claim 1 characterises a first solution to the problem. According to this claim the actor is biased for test purposes with a predetermined current, the time change of the position of the actor with the predetermined current is detected and deviations between the measured time change and the stored ideal values are identified as faults.

The method according to the invention can be used in various extremely flexible ways for testing purposes.

Claims

Claims
2 to 4 are directed to advantageous ways of carrying out the method

according to the invention.

is With the features of claim 5 it is ensured that the actor is in no way supplied with further current if an end stop is reached. Any further supply of current could lead to damage to the actor or clutch device.

A further solution to the object of the invention is characterised in claim 6. With this method during normal operation of the clutch device an entry is made in a faulty memory which in the event of maintenance can be readily retrieved or results in a display in the switch board of a motor vehicle.

Claims 7 and 8 indicate further advantageous ways of carrying out the method according to claim 6.

Claim 9 relates to a dev according to the invention.

ce for carrying out the method According to the invention the object of the invention is 35 achic-.,-ed through a method for testirig an automated clutch SP2281.P3 12 November 1998 is provided, more particularly mounted in the drive train of a motor vehicle and has a control device containing a microprocessor, an electrically operated actor governed by the control device, a motion transfer device between the actor and an operating lever of the clutch and a position sensor for detecting the position of the actor, wherein the actor is biased for testing purposes with a predetermined current, the time change of the actor with the given current supply is determined and deviations between the measured time change and stored ideal values are identified as faults. This clutch device is thus contained in the vehicle and can be tested there with the method according to the invention. It is expedient if the time period which the actor requires to pass through a predetermined stretch is analysed. It is also expedient if the speed curve of the position change of the actor is analysed. It is also advantageous if the predetermined current supply of the actor is carried out in the case of partial systems of the motion transfer device connected up to the actor. Furthermore it is expedient if positions detected by the position sensor are recognised as end stops of the clutch whereby the current supply to the actor is switched off when these are passed, and a diagnosis system is provided for the position sensor which diagnoses predetermined events as faults of the position sensor during which process the predetermined current supply of the actor for test purposes is blocked when a fault exists in the position sensor.

device wherein the clutch device Furthermore, with methods or devices for testing an automated clutch device, more particularly a clutch device mounted in the drive train of a motor vehicle, which clutch device has a control device containing a microprocessor, an electrically operated actor governed by SP2281.P3 12 November 1998 the control device, a motion transfer device between the actor and an operating lever of the clutch, and a position sensor for detecting the position of the actor, it is advantageous if predetermined states of the clutch device are detected by associating the position of the actor with its output capacity and/or slip of the clutch and/or torque acting on the clutch input and a fault entry is made in a memory of the control device if a predetermined state lies outside of a predetermined 10 setting interval of the actor.

It is also advantageous if a fault entry is made if the bite point of the clutch is sensed outside of a predetermined setting interval.

is It is also expedient if a fault entry is made if the friction value of the clutch lining lies outside of a predetermined range.

The invention further relates to a device for carrying out a method according to the invention.

The invention will now be explained in further detail with reference to the diagrammatic illustrations in the 25 drawings in which:

Figure 1 is a view of a drive train of a motor vehicle; and Figure 2 shows details of a clutch device contained in the drive train according to Figure 1.

According to Figure 1 the drive train of a motor vehicle has an internal combustion engine 2 which is connected by a clutch 4 to a gearbox 6 which in turn is connected by a SP2281.P3 12 November 1998 - 5 Cardan shaft 8 and differential 10 to the driven rear wheels 12. The front wheels 14 of the motor vehicle are not driven in the illustrated example.

The structure of the clutch 4 is known per se and contains inter alia a clutch disc 16 which is connected rotationally secured to the crankshaft of the internal combustion engine 2, as well as a pressure plate 18 which is connected rotationally secured to the input shaft of the gearbox 6 and can be released from friction engagement with the clutch disc 16 by means of an operating lever 20 against the force of a plate spring.

The gearbox 6 is a conventional manual shift transmission which can be shifted by means of a shift lever 22.

For operating the operating lever 20 an actor 24 is provided, more particularly an electric motor, which is governed by an electronic control device 26. The structure of the electronic control device 26 is known per se and contains a micro processor with associated memory devices, interfaces etc. Its input is connected to a position sensor 58 for detecting the position of the actor 24 or operating lever 20 so that an ideal position of the operating lever 20 can be regulated extremely accurately with the control device 26.

Furthermore the control device 26 is connected to a sensor 29 for detecting the gear of the transmission 6, a sensor 30 for detecting a wheel speed and through a data line 31, for example a CAN-bus to an engine control device 22 whose structure is likewise known per se and contains a micro processor, memory devices, interfaces etc.

SP2281.P3 12 November 1998 b Operating parameters of the internal combustion engine, such as their temperature from a temperature sensor 34, the speed from a speed sensor 36 and the position of a throttle valve or load control member from a load sensor 38 are supplied to the inputs of the engine control device 32. Outputs 39 of the control device 32 control the operation of the internal combustion engine.

Figure 2 illustrates details of the clutch operation according to Figure 1:

The actor which is marked overall by 24 contains an electric motor 40 which drives through a worm gear 42 a crank drive 44 from which a linearly guided crank rod 46 projects which is connected to a piston rod 48 which belongs to the piston 50 of a master cylinder 52.

The rotary position of the electric motor 40 and thus the position of the piston 50 is detected by means of the position sensor 28 which is formed as an incremental sensor and which during rotation of the worm connected to the drive shaft of the electric motor 40 about a relevant predetermined angular amount sends out an impulse.

The master cylinder 52 is connected through a lead 55 to a slave cylinder 56 in which a piston 58 operates whose piston rod 60 operates the operating lever 20 of the clutch 4. The wall of the master cylinder 52 has a snifting bore 67 which is connected to a supply container 68 for hydraulic fluid. A relaxation or compensation spring 69 is provided in the actor 24 to relieve the electric motor 40 and the hydraulic system of the forces of the clutch resetting spring (not shown).

SP2281.P3 12 November 1998 7 - The construction and method of functioning of the clutch operation are known per se and will therefore not be described in further detail. The electric motor 40 can be controlled for eXample by pulse width modulation wherein with constant pulse level the pulse width determines the torque and the pulse direction determines the rotary direction of the motor.

For clutch devices of the described kind which can also be used in connection with an automated manual shift transmission, a high functioning diagnosis is required for a rapid fault search, detection of the state of wear of the clutch device and for guaranteeing functional reliability. It is thereby expedient to supply the actor 24 or its electric motor 40 with current in a predetermined example with predetermined the crank rod way for diagnosis purposes, by way of voltage impulses of constant level and pulse width, and to analyse the movement of 46 and operating lever 20 by means of the 20 position sensor 28.

When a predetermined current is supplied a predetermined sequence of output signals of the position sensor 28 recorded in a memory of the control device 26 corresponds 25 to a satisfactory operating state of the clutch device. In the event of deviations of the time sequence of the output signals of the position sensor 28 from the ideal curve this is regarded as a fault and displayed in a fault indicator or display of the control device or a diagnosis 30 device connected up to same.

It is thereby possible to determine the process time which the actor 24 requires to operate the clutch 4 about a predetermined path stretch or to analyse the time sequence SP2281.P3 12 November 1998 of the impulses of the position sensor 28 in detail with high resolution.

For a more accurate analysis of the operating device it is possible for example to separate the slave cylinder 56 and to replace it by a springloaded cylinder so that only the master cylinder 52 can be checked for satisfactory functioning. The slave cylinder 56 can then be connected whereby the operating lever 20 is replaced by a spring so that after the master cylinder the slave cylinder is checked for satisfactory functioning. The operating lever 20 is then connected so that the overall system is checked.

It is evident that other measuring sequences are possible within which for example the mostly longer lead 55 or hydraulic stretch can be targeted and checked or the actor 24 alone can be checked. No external sensors are required for measurements since all the necessary values can be stored in the control device.

service The dynamic requirements can be established in experiments, stored in the form of ideal values and then readily checked to ensure they are met by customer Through the variable fittings of the system (actor, actor + master cylinder, actor + master cylinder + hydraulic stretch etc) it is possible to deal with individual problems inside the entire device.

The control device 26 of Figure 1 can also be replaced by an external control device, for example a diagnosis unit of customer service. This diagnosis unit can itself contain test routines and associated stored ideal values with a current supply for the actor. It can be connected 35 to the actor 24 located in the vehicle or also to actors SP2281.P3 12 November 1998 located outside of the vehicle which are connected where applicable to further structural groups of the clutch device. Thus the method according to the invention can be used for testing part or complete systems inside and 5 outside a motor vehicle.

During operation of the clutch in the vehicle a running fault diagnosis is carried out whereby for example faults of the position sensor 28 are sensed if its signal sequence or evaluation does not meet certain criteria or an end stop is not recognised, for example by counting beyond a certain counting state with a simultaneously increased output capacity of the engine 40. With the presence of such a faulty state in the control device 26 a diagnosis-controlled current supply to the actor 24 is advantageously interrupted so that it cannot lead to damage to the actor or operating device if the diagnosis is carried out in the vehicle.

It is evident that the method according to the invention can also be used with modified actors and transfer members between the actor and clutch. The method is possible through mere programming of the computer in the control device 26 and/or diagnosis unit which is attached to the control device 26 or is connected up directly to the actor 24. It is evident that the position sensor 28 can also be fitted on the operating lever 20 or a further position sensor can be attached there.

With the clutch device depicted it is possible to detect in normal operation the bite point of the clutch. This is the point at which the clutch 4 is closed so far that for example on driving off in the vehicle or after a shift process a predetermined moment is transferred from the 35 internal combustion engine 2 to the transmission 6. The SP2281.P3 12 November 1998 - engine moment can be retrieved from a characteristic field which indicates the moment of the internal combustion engine in dependence on its speed and position of the load setting member, for example a throttle valve. The relevant bite point is detected by evaluating the signal of the position sensor 28 in the control device 26. The bite point changes for example with increasing clutch wear. If it lies outside of a predetermined area then this is advantageously registered as a fault in the control device 26 which fault can then be retrieved by means of a diagnosis device.

The friction value of the clutch can be determined by calculating the clutch slip (speed difference between speed of the internal combustion engine and the input shaft of the gearbox 6, calculable from the wheel speed and overall transmission ratio) in dependence on the position of the clutch (for example clutch fully closed or clutch opened from the closed position by a predetermined stroke or closed from the bite point by a predetermined stroke) and the torque of the internal combustion engine. If the friction value is outside of a predetermined area stored in the control device 26 then this also advantageously leads to a fault entry which can be retrieved with diagnosis. It is evident that further deviations from ideal values or ideal areas, for example also as a result of the fact that air is present in the hydraulic transmission system, can be detected and lead to fault entries in the memory of the control device 26.

With a method for testing an automated clutch device, more particularly a clutch device mounted in the drive train of motor vehicle and which has a control device containing microprocessor, an electrically operated actor governed by the control device, a motion transfer device between SP2281.P3 12 November 1998 - 11 the actor and operating lever of the clutch, and a position sensor for detecting the position of the actor, the actor is biased for test purposes with a predetermined current, the time change of the actor with the predetermined current supply is detected and deviations between the measured time change and stored ideal values are identified as faults.

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.

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 SP2281.P3 12 November 1998 process steps or sequence of process steps insofar as these refer to manufacturing, test and work processes.

SP2281.P3 12 November 1998 13 - Claims 1. Method for testing an automated clutch device, more particularly a clutch device mounted in the drive train of a motor vehicle and having a control device containing a microprocessor, an electrically operated actor governed by the control device, a motion transfer device between the actor and an operating lever of the clutch, as well as a position sensor for detecting the position of the actor, wherein the actor for testing purposes is biased by a predetermined current, the time change of the actor with the predetermined current is detected and deviations between the measured time change and stored ideal values are identified as faults.

is 2. Method as claimed in Claim 1, wherein the time length required for the actor to travel through a predetermined stretch is analysed.
3. Method as claimed in any preceding claim, wherein the speed curve of the position change of the actor is analysed.
4. Method as claimed in any preceding claim, wherein the predetermined current supply to the actor is carried out when parts of the system of the motion transfer device are connected to the actor.
5. Method as claimed in any preceding claim, wherein 30 positions detected by the position sensor are identified as end stops of the clutch whereby the current supply to the actor is switched of f when these are passed, and a diagnosis system is provided for the position sensor which diagnoses predetermined events as faults in the position sensor, during which process the predetermined current SP2281.P3 12 November 1998 14 supply to the actor for test purposes is blocked when a fault exists in the position sensor.
6. Method for testing an automated clutch device, more particular a clutch device mounted in the drive train of a motor vehicle, which clutch device has a control device containing a microprocessor, an electrically operated actor governed by the control device, a motion transfer device between the actor and an operating lever of the clutch and a position sensor for detecting the position of the actor, wherein predetermined states of the clutch device are detected by associating the position of the actor with its output capacity and/or slip of the clutch and/or torque acting on the clutch input and a fault entry is made in the memory of the control device when a predetermined state lies outside of a predetermined setting interval of the actor.
7. Method as claimed in Claim 6, wherein a fault entry is made when the bite point of the clutch is sensed outside of a predetermined setting interval.
8. Method as claimed in Claim 6 or Claim 7, wherein a fault entry is made when the friction value of the clutch lining is outside of a predetermined area.
9. Device for carrying out a method more particularly as claimed in any one of the preceding claims.
10. Method for testing an automated clutch device, more particularly a clutch device mounted in the drive train of motor vehicle and having a control device which contains microprocessor and an electrically operated actor which is governed by the control device characterised by its SP2281.P3 12 November 1998 special method of operation and design according to the present application documents.
11. Method for testing an automated clutch device substantially as herein described with reference to the accompanying drawings.
12. Device for testing an automated clutch device substantially as herein described with reference to the accompanying drawings.

SP2281.P3 12 November 1998