GB2315836A

GB2315836A - Automatic clutch having a control device which activates an emergency routine

Info

Publication number: GB2315836A
Application number: GB9719204A
Authority: GB
Inventors: Burkard Kremmling; Michael Salecker; Martin Zimmermann
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1993-08-03
Filing date: 1994-08-01
Publication date: 1998-02-11
Anticipated expiration: 2014-08-01
Also published as: GB2310473B; GB2310473A; GB9719204D0; GB2315836B; GB9706152D0

Abstract

An automatic clutch control device activates an emergency routine when, for example, a voltage supply defect, proportional valve defect, pump relay defect or hydraulic supply failure is detected. On detection of such failure/s the control device initiates a system shut down, ie a software emergency shutdown and/or a hardware emergency shutdown, which closes the clutch. In other situations, such as a faulty sensor, emergency software is run which retains normal clutch operation during gear changes and a tip-in and back-out control is blocked. When failures occur such as a processor failure, clutch path sensor fault or a fault of several sensors the control device automatically switches from software emergency running to hardware emergency running which, for example, switches on a warning light and/or, depending on engine speed, closes the clutch. Hardware emergency running also opens the clutch at small throttle valve angles and closes the clutch at large throttle valve angles.

Description

2315836 Motor vehicle The invention relates to motor vehicles which have

an automatic clutch provided in the torque path between the combustion engine and a stepped gear change, as well as at least one switching and control unit or regulator for same. These have become known by the term "Electronic Clutch Management" or IIECMII in short, eg in connection with DE-OS 40 11 850.

The object of the present invention is to increase the safety of vehicles equipped with such systems by making the driver aware through the invention not to get out of the vehicle leaving the gear engaged in certain operating 15 conditions, such as when the vehicle is stationary with the engine running and gear engaged, such as for example when stopping in front of the garage (in the corresponding operating state the clutch is in the ready position because the accelerator is not operated), because in this case, in 20 the event of a fault in the disengagement system, eg a drop in pressure in the hydraulic system of the automatic clutch the clutch would close. Furthermore the comfort of the vehicle is to be increased, by, for example when changing gear, being able to transfer the engine torque more 25 sensitively to the drive wheels, and furthermore starting off on icy roads should become much easier. The object of the invention is also to make such systems and thus vehicles equipped with same more economical, to make the control regulation more finely sensitive and faster-acting and in 30 the event of faults to make these known to the driver and/or the workshop by storing such faults in for example a fault memory store, preferably a non-volatile fault memory store. Furthermore the electronic hardware used should be simplified and capable of universal use, the number of 35 senders and/or receivers should be kept as low as possible SP1427.P3C September 9, 1997 and furthermore the smallest possible alterations need have to be made when fitting an ECM in vehicles.

According to the invention, there is provided a motor vehicle with an automatic clutch in the torque path between an engine and gearbox and with at least one control device, such as an electronic clutch management system therefor, wherein upon failure of the system an emergency routine such as a software emergency shutdown and/or hardware emergency shutdown is activated.

Further features and details of the invention will become apparent from the following description and from the dependent Claims 2 to 29.

The invention will now be explained in further detail with reference to the embodiments shown in the drawings.

Figure 1 thereby shows the arrangement of the hydraulic 20 system components with transducer cylinder 1, receiver cylinder 2 with the hydraulic pipe 3 connecting same, and the supply container 4 on one side as the brake f luid circuit 5 and on the other the hydraulic circuit of the vehicle 6, consisting of the engine 7 with pump 8, pressure restrictor valve 9, filters 10 and 11 and non-return valve 12. This hydraulic circuit also contains an accumulator 13, a pressure sensor 14, the 4/3-way valve (proportional valve) and the transducer cylinder 16 of the hydraulic circuit of the vehicle. The piston rod 17 of the cylinder 16 is at the same time the input piston rod for the piston cylinder unit 1. The piston rod 17 is used to operate a rotary potentiometer 18 which produces and sends out a signal for the clutch position. The piston rod 19 of the receiver cylinder unit 2 operates the clutch operating lever 20 which 35 in turn operates a disengagement bearing 21 through which SP1427.P3C September 9, 1997 3 the plate spring 22 (shown diagrammatically) of the clutch 23 (likewise shown diagrammatically) is operated.

The pipe 24 connecting the cylinder unit 1 with the supply 5 container 4 opens into the cylinder unit 1 through the snifting bore 25 shown in further detail in Figures 2 and 3.

IMPLEMENTATION IN DETAIL The torque build up when starting up is determined by three independent calculations. These are the prediction regulator, the disengagement strategy and the crawl regulator. Each of these regulators calculates an ideal torque wherein the maximum torque is adopted as the resulting starting torque.

is SP1427.P3C September 9, 1997 Flow diagram of the starting regulation Starting (init nu = nschl "I 1Odec. Rampe = 0] YM-s NO .__Ierator:o::7!! MRsoff Prediction regulator MRsoll = Disengagement routine no = MAX (1200. nanf) no i nmot NO MRsdLn2 (%=4. r42 - (no - nmot)/106 MRsofl.n2 0 YES Brake V Gp = Erm NO 0 YES NO Slope Slope 02 Nm Slope - Skmoe Q2 tn tr I GP-detecian Ml:tsollnZ = MAXNRscllxg, Sope) MRS01 MRSOU.n2 -Y',Zs!77 Slope = 0 Isoff KUPP_KVIVIRsoff) celerator not oPerated no, e t operat!5 Gp-detecton NO nu + inc 600 nmot YES 0 YES NO nu = nu + Inc nu = MAX(600. nu = MAX(200.

nsc.hl - 10'de--) nu - dec) Fig. 1: Sauc-,oc;ram of the crawl regulator embedded in "dr,lng" rate SP1427.P3C September 9, 1991 - 5 Here the following applies:

n, lower speed barrier (rpm) n. upper speed barrier (rpm) n.,,, starting up speed (rpm) n, engine speed (rpm) n.,hl filtered slip between engine and gearbox (rpm) MRSoll ideal friction torque (Nm) MRsoll,n 2 ideal friction torque of crawl regulator (Nm) inc=4 increment for change in lower barrier (rpm) dec=4 decrement for change in lower barrier (rpm) When first starting off the crawl regulator is initialised is as follows:

- lower barrier nu to ideal slip + offset - slope to torque = 0 The crawl regulator is comprised of a n 2 -regulator which calculates its torque in dependence on the engine value and a value reset to the gearbox speed, and of a time-dependent torque slope with a rise of 20 Nm/s. The maximum torque is adopted as the crawl torque.

The torque of the slope is built up when there is no throttle and no brake operated. if the foot brake is operated or the hand brake tightened then the torque breaks down with the same gradient with which the torque was previously built up. The slope serves to close the clutch in the event of longer crawling in each case when the torque of the n 2 -regulator, conditioned through the increasingly reducing slip, passes to nil. The n 2 regulator alone would set a fixed slip which in the event of longer crawling could lead to an unacceptably high wear on the clutch.

SP1427.P3C September 9, 1997 The ideal friction torque of the starting-up regulation with prediction regulator is indirectly dependent on the throttle valve. If the accelerator is pressed down then as a rule S the prediction regulator is operated. Otherwise the disengagement routine predetermines the path of the ideal torque. Thus in the event of an interrupted start the disengagement routine is activated in order to break down the torque of the prediction regulator to the crawling torque.

The n' regulator has the following algorithm:

MRsoll,n 2 = (nschl - nu) 2. (n. - n,,,.,).

The upper barrier n,, has the result that the torque breaks is down as the engine speed increases, thus when pressing down the accelerator, and on exceeding this barrier is set completely to nil. This means that a torque is immediately built up through the n 2 - regulator which is however exceeded when accelerating after a short time by the prediction regulator and is solely determined by this. A prerequirement for a "comfortable,, adoption through the prediction regulator is a small difference between the gradients of the two ideal torques in the transfer point.

The lower barrier n,, takes care of the torque build-up when crawling, so long as the accelerator is not depressed, and for a torque break-down when the brake is operated. The barrier is initialised when entering the state "starting up" to the actual slip + offset. The additional offset serves 30 for the ideal clutch position to proceed from the stroke to the engagement point according to an e-function and thereby for the actual clutch position to cause no torque overswing. The reduction in the lower barrier ri,, when understepping a boundary engine speed of 1000 1/min with no accelerator 35 activation, leads to an increase in the ideal torque. In SP1427.P3C September 9, 1997 order to prevent a possible stalling of the engine there is a lower engine speed of 600 1/min at which the decrementing is adjusted by n,, and the ideal torque is increased no further.

If the prediction regulator takes over the regulation as a result of a higher ideal torque then the slope is initialised to nil so long as the prediction regulator provides the higher ideal torque. Similarly also n,, is increased to its maximum when the accelerator pedal is activated, and thus the ideal friction torque of the n' regulator is broken down in order to ensure a safe adoption of the prediction regulator. Furthermore in the event of an interrupted start where the ',starting" is not abandoned, the is n-regulator is initialised internally.

2. ENGAGEMENT POINT DETECTION In the present embodiment the clutch position is measured on the transducer cylinder (GZ) in the hydraulic block and not on the receiver cylinder (NZ) on the gearbox bell (see the drawing in enclosure 1).

The temperature -dependent volume expansion of the brake fluid column between GZ and NZ falsifies the relationship of the actual clutch position (on the NZ) and the measured clutch position (on the GZ) so long as the clutch is at least partially open and thus the snifting bore in the GZ is not released.

When the clutch is closed, the system is "newly compensated" through a volume compensation through the sni fting bore in the GZ.

SP1427.P3C september 9, 1997 Even after a few minutes stationary the volume change as a result of the temperature effects can cause several millimetres lift in the GZ.

When the clutch is opened the clutch position in the GZ is constantly regulated, ie when the brake fluid column warms up the piston moves in the NZ and the clutch is opened further (danger of overpressing the clutch!).

The control unit realizes nothing of this process. The next starting process would therefore be severely affected:

Basically an engagement paint accepted with a 0.5 mm error can already be traced subjectively in the case of all strategies (crawling, starting, reengagement, disengagement is to gear-change or stationary).

2.1 ENGAGEMENT POINT STRATEGY:

In order to have the engagement point always set as accurately as possible the following strategy is programmed 20 into the control unit. A difference is made between a lIGPstationaryn, a nGp-push" (are recorded in the background) and a current (is used for regulation) engagement point.

If the vehicle is set stationary with the engine running 25 then there are principally two possibilities:

1. The driver has engaged the neutral gear position.

2. The driver has engaged gear and has a foot on the brake (or the handbrake is tightened) so that the vehicle does not crawl forwards.

In the first case there is the possibility of closing the clutch and thereby releasing the snifting bore so that volume compensation can take place. For this the clutch is SP1427.P3C September 9, 1997 cyclically closed for 1 second (eg every 3 0 seconds). on releasing the switching intent or leaving the neutral position the process is interrupted and the clutch immediately opened. If the volume compensation has ended 5 then the actual engagement point is set the same as the npush engagement point".

In the second case no snifting can take place. Therefore the engagement point is updated periodically (eg every 30 seconds). The clutch is thereby closed slowly (torque build-up as when crawling) until the engine speed shows a reduction of 80 1/min. The engagement point thereby detected is recorded as the nstationary engagement point".

Should the engine speed not reach the required reduction then for safety reasons the detection is stopped after a certain time (of eg 1.27 seconds). This time corresponds to the calculation of an engagement point displacement of 0.5 mm and is adopted as such. This is also the maximum deviation possible fixed in the program of + 0.5 mm between the detected ',stationary engagement point" and the current engagement point (for a more detailed description see Section 2.2.1)

After detection the torque is again slowly broken down to 25 nil (as when stopping crawling). If the clutch is again opened to engagement point + offset then the current engagement point is set the same as the "stationary engagement point".

If the driver now wants to drive or crawl forwards then the current engagement point is already adopted for this motion. If at the end of the journey or gear change the clutch'is closed for a minimum of 1 second and is thus 'Isniftedll, then SP1427.P3C September 9, 1997 as above (Case 1) the 'I push engagement point 11 is adopted as the current engagement point.

The detection of the "Push engagement point" is carried out during push engagement. The condition here is that the last 'Isnifting11 must be set back a maximum time (eg 30 seconds) which however means practically no restriction since this is normally always the case. The maximum permissible change of the "push engagement point" to the current engagement point 10 would be restricted to 0.2 mm.

The "push engagement point" is stored as the adaptive parameter when switching off the system and is adopted as the current engagement point when activated.

is Changing over a newly detected engagement point may only take place when the clutch is either fully open or fully closed since during a coupling process a sudden change in the engagement point would cause a sudden change in the 20 transferrable torque.

2.2 Engagement point detections 2.2.1 Engagement point detection when stationary The engagement point detection when stationary is carried out by analysing the speed path and estimating the engagement point therefrom.

When crawling forwards, under certain starting conditions as a result of the action of the crawl regulator, the clutch always begins to close with the same relatively constant speed.

SP1427.P3C September 9, 1997 By closing the clutch the engine speed drops as soon as torque is transferred on the condition that the accelerator is not applied and the idling regulator has not yet responded. Starting from an idling speed fluctuation of 50 1/min, with the correct engagement point and a level road surface a speed drop of 80 1/min is always achieved within roughly the same time span. If the engagement point in the vehicle is moved to the left in comparison with the clutch characteristic line implemented in the computer (see diagram 10 below), then this time span increases since the actor must cover a larger path from the starting position "zero point + stroke,, with constant adjustment speed. When the engagement point is moved to the right then the time span is decreased.

is 1200- Cumh ciaracteristic 1COO SCO E Z b (D ECO Engagement Paint E UNMI 400 2GO 0-- + 1 0 2 3 4 7 Stroke Imm] SP1427.P3C September 9, 1997 The engagement point displacement can now be calculated from the difference between the nominal time span and the measured time span t- t,, ..) and the initial adjustment speed i.-CM# GP t - tnom) inom The engagement point detection can be carried out both when the foot brake is operated and when the hand brake is operated.

Each engagement point detection can only be carried out when slipping the clutch. In order to keep the wear on the clutch to a minimum the engagement point detection when stationary is therefore only carried out every 30 seconds at maximum.

The entire algorithm which is written as its own sub-routine should constantly be called up "when driving". The initialisation for this is always called up when entering into "driving" as well as also during "driving" when the RAMPE is nil, ie crawling has not yet begun. The updated algorithm is shown in the following structogram.

Initialisation:

CC)NS-jAW 1 norn 2.3. trorn = 1.1. trnax - 1315 (nt I b(j nMor.r I+ U) 505 ' so U n ke - open) GP) 30) Y=:NO FLAG - TRUE FIAG - FALSE rirmt rnerke " %01 Y-S FLAG L1 NO 1 n=t, SO YES NO NO W. VrrM YES rampe 1 tmu NO (rarr.pe "O.CC5 -;mrn C-P 0.5 tGP = C) tc-p 0 FLAG - FALS-E FLAG - FALSE FLAG FALSE' SP1427.P3C Rg, 2: scr=.cgrarn for irie engagernent point detectcn when smtcnary september 9, 1997 engine speed rlmt,merke fixed' engine speed when entering into the engagement point detection for determining the speed drop [rpm] nj, idling speed [rpm] nf vehicle speed [km/h] GP relative engagement point displacement (in relat ion to the last detected engagement point) [mm] 1 1 nom starting adjustment speed of clutch (nominally fixed from measured values) [MM/S1 t.' Adjustment time (nominally fixed from measured values) until engine has dropped as the crawl regulator starts to work from the idling speed to the reference point n,,,,= 650 1/min, [s] tu maximum time to breaking off engagement point detection, significantly owing to restriction of GP to O,Smm, [s) tGP Time span variable, is initialised in the event of 'Isnifting" and at end of engagement point detection, [s] rampe slope from crawl regulator, serves here as time span variable FLAG logical variable; allows engagement point detection when the entry conditions are no longer fulfilled; is negated as soon as the engagement point detection is concluded LL idling switch; if TRUE then "no accelerator" The starting conditions encountered here Cengine speed approximately idling speed, vehicle practically stationary) limit the frequency of the engagement point detection.' However the nominal adjustment speed I',,, can only be SP1427.P3C September 9, 1997 reached under these starting conditions with a correct engagement point (reproducibility!).

2.2.2 Push engagement point detection when re-coupling If the engine speed af ter a gear change lies below the gearbox speed then the slowing engine is accelerated during the following engagement of the gearbox. This process takes place with each reverse switching with engine thrust operation and also in part during high-speed changing in the upper gears.

The basic idea of the detection now lies in transferring to the clutch at the time when the engine speed path has a minimum (stationary state, no engine acceleration), exactly that torque which corresponds to the instant drag torque of the engine (see the drawing in enclosure 2).

The drag torque can be detected from the characteristic field in dependence on the engine speed and assigned to a corresponding clutch position through the clutch characteristic line.

From this clutch position it is reset to the position in which a torque =0 is transferred.

Conversion So that the detection can proceed logically some conditions are linked (see structogram):

the filtered slip must be constazitly negative (nGetr > riMotor) up to the time when the Gp, is detected; SP1427.P3C September 9, 1997 the LL-switch must be active (DK= 0) so that the drag torque is not compensated by the engine torque; the engine speed must not be below 1300 1/min because otherwise the idling regulator may accelerate the engine (drag torque from characteristic field then not available);.

furthermore the engine speed must not exceed 2800 1/min so that the push torque is not too big (detection' should take place as close as possible to the engagement point so that the characteristic line errors have less influence.); the Gp is detected at the time when the engine gradient is passing through zero. The gradient must thereby not exceed about 83 1/S2 in order to rule out is faulty measurements; the new value may differ from the detected Gp by 0.2 mm max.

&nmotcr.k nmomr.k - nm=rk- l C-car engagd YES NO Cp-don sdU actve YES NO A (detected sip. Cj A A 0 (13C0 U/Min A c 2= U ICASS (A, r==.k),411 YES -2 NWO Gph=--- CI='i Pazh Cur=i rath (f mcrcrm.(t)) ASS (GokL.rZ - Gp) 0.2r7..r-n j: -okIrZ Gp) - I YES NO CIrk= C-P 5"C-3mc;%cuz - C.0) QZ-, 1 1 1 Fag 7.7 L.Rag 7.1 1 (Go dere=cn ccrr-.cleret cr carnot te camed cut) C) SP1427.P3C September 9, 1997 2.2.3 Pull engagement point detection when recoupling The pull engagement point detection when recoupling can take place for example in that the surface between the engine speed and a value reset to the gear speed is integrated over the time. If the surface exceeds a fixed maximum value then the engagement point is moved into the clutch closing direction. If the surface understeps a fixed minimum value then the engagement point is moved into the clutch opening direction.

3. SAFETY PHILOSOPHY OF =RAULIC ACTUATOR 3.1 System monitoring is A detailed FMEA of the ECM system was carried out. This showed that it is necessary to differentiate between 3 types of breakdown:

Breakdown of the sensor Processor breakdown or breakdown of several sensors Breakdown of voltage supply, end steps or hydraulic supply.

The ECM system recognizes two different emergency running stages, software emergency circuit and hardware emergency circuit. The system control light shows whether an emergency running is active.

More serious faults are indicated by a rapid flashing light flashing frequency about 4 Hz) This is the pase when:

pressure drops hardware emergency switching is activated, ie in the event of SP1427.P3C September 9, 1997 - processor failure - clutch position fault - multiple sensor error Less serious faults are indicated by a permanent light.

This applies with simple sensor faults, with the exception of the "clutch position,' fault.

The warning light indicates to the driver that the 10 functioning systems have broken down or are only operating to a restricted amount.

Table 1 illustrates the various emergency running stages with a description of the effects on the clutch control.

is 3.1.1 Sensor breakdown Plausibility controls of the sensor signals are constantly taking place. If a fault is detected then a corresponding emergency program is switched on. This software emergency circuit (see Section 3.2.1) allows the basic functions to continue, ie the automatic clutch operation for driving and changing gear. However comfort restrictions must be accepted here. If several sensor faults occur at the same time then the hardware emergency circuit is activated (see Section 3.2.2).

3.1.2 Processor breakdown The processor is monitored by an external watchdog. If as a result of a program crash the processor can no longer reset the watchdog timer then the watchdog triggers a processor reset. With a reset the clutch control is SP1427.P3C September 9, 1997 automatically switched over to a fixedly wired control circuit, the socalled hardware emergency circuit.

3.1.3 Failure of voltage supply, end steps or hydraulic 5 power In the event of these serious faults a system shut down takes place which causes closing of the clutch.

Case Emergency step Vehicle reaction occurs when 1 'normar ECM-control automated coupling when driving and - no fault (no emergency running during gear change active) - special clutch control for optimising dp4n and back-out reactions in vehicle 2 software emergency - "normal" automatic dutch function when fault of one sensor (apart from running driving and during gear change with dutch-path sensor error) reduced comfort - Tip-in and back-out control blocked (ie dutch remains closed) 3 hardware emergency - starter lock released - processor failure running electropump time controlled for onloff - dutch path sensor fault switching - fault of several sensors - at engine speed < 300 llmin ==> dutch dosed at engine speeds > 400 llmin ==> dutch position dependent on throttle angle:

- at small throttle valve angle, dutch is opened - at large throttle valve angle, the dutch is dosed - warning light switched on 4 System shut down dutch dosed - voltage supply defect (cable, voltage regulator) proportional valve end step defect - pump relay end step defect - failure of hydraulic supply.

TABLE 1: ECM Safety Philosophy 3.2 EMERGENCY CIRCUITS is 3.2.1 Software emergency circuit SP1427.P3C September 9, 1997 If at least one fault is entered in the current fault memory then the flag 11 SW- emergency" is set and the warning light shows permanent light (Exception: in the event of "pressure drop,' rapid flashing light with about 4 Hz flashing 5 frequency).

The operating mode 11 dragging" is blocked. The other measures and consequences with the various faulty conditions are listed in Table 2.

These fault measures are rescinded if the flag 11SWemergency" is cancelled. This occurs if there is no longer any current fault and the neutral gear position is engaged or the clutch is closed. Cancelling the fault measures only is in the non-critical states "neutral position" or "clutch close& prevents the switching back to the normal operation being perceptible to the driver.

The exceptions here are the faults:

gear position and idling switch which are immediately reset as soon as the relevant fault no longer exists. With these types of faults the cancellation of the replacement value in the event of the fault no longer being present is also then uncritical if the neutral position is not engaged.

Type of fault Measures Effects 1. Engine speed signal Changeover to engine None secondary speed 2. Gearbox input speed Replacement value nc, = 0 minTemperature protection measures signal come into effect Gear recognition restricted Driving protection for high gears out of (difference only made between force 1 st gear, 2nd gear and neutral Clutch opens when accelerator pedal not activated (freewheel action) Recoupling in the train uncomfortable SP1427.P3C September 9, 1997 CNertuming protection not operative 3. Tacho speed signal Replacement value nF' 0 min' - smoother coupling behaviour at high Gear recognition restricted (as gears 2) 4. Throttle valve signal Replacement value aDK = 50 Starting speeds not dependent on throttle valve angle Recoupling not adapted (either too hard or too soft depending on situation) Rapid uncomfortable disengagement 5. Gear position Replacement value set to 1 st Softer coupling behaviour at high gears transducer signal gearrange Gearbox chatter and gearbox damage Starter block deactivated possible or provokable 6. Pressure sensor 50% switch on time - pump 'none signal cycle activated 7. Switching intent Switching intent flag = "false" Increased amount of shift force to switch signals set change into neutral gear position 8. Idling switch signal Idling switch = 'false" set at DK Driving off poorly metered (still only > 50 crawling or driving with DK > 5 possible TABLE 2: Measures and consequences with various fault situations in the software emergency circuit.

3.2.2 Hardware emergency circuit The system contains a f ixed-wired emergency control. In order to maintain the system pressure the electro-pump is controlled with a fixed beat (ie 10 seconds on, 10 seconds off, 10 seconds on...). Below a minimum engine speed (stationary engine) the clutch is closed (parking lock, security against accidental rolling). When the engine is running the clutch is controlled directly through the throttle valve signal. Thus the clutch is opened with a small throttle valve angle and closes with a large throttle valve angle. The pulse width modulated signal of the throttle valve is used directly to control the valve.

The emergency control allows the car to be driven with a low risk of danger up to the next halt. Driving is however not 20 possible in all cases since the closing process of the clutch can indeed be controlled through the accelerator SP1427.P3C September 9, 1997 pedal but the ability to meter out fuel is however very restricted.

Starting the engine is blocked when the emergency control is active. Deactivating the starter lock is only possible by plugging in a bridging plug (see Section 3.2.3).

The hardware emergency circuit becomes active when the system detects a multiple sensor fault (see Section 3.1) or the clutch position signal is destroyed or breaks down. A special operating state of the software control (Shut down) ensures the system control is transferred to the fixedly wired emergency control. The hardware emergency r = ing is in this case not reversible and can only be lifted by is switching off the controlunit (ignition off, driver's door closed).

The correct functioning of the software control is monitored by a socalled "watchdog". If the processor does not send a trigger signal to the externally fitted "watchdog" circuit at regular intervals then this circuit triggers the hardware emergency control and the processor is restarted (reset). If the processor works correctly again after renewed high speed running then the hardware emergency running is rescinded in this case.

The hardware emergency control is generally active in the high speed running phase of the software system up to about 100 ms after switching on the control unit.

On encountering the conditions: engine speed, 500 min-1 and (foot brake or handbrake) operated SP1427.P3C September 9, 1997 an engine shut-down is activated in the hardware emergency control which acts for a max. of 3 seconds. (See Section 3.3 for detailed description of this function).

If with the activated hardware emergency running the starter block bridge is plugged in and an attempt is made to start up, then if the foot or handbrake is operated, the engine shut-down comes into effect. Since however the engine shutdown only lasts for a maximum of 3 seconds the engine can 10 nevertheless be started.

3.2.3 Deactivation of the starter blockade The starter blockade can be circumvented by placing the is bridging plug in the "starter release" socket.If the starter block bridge is pushed in then the system warning light rapid flashing light comes on (flashing frequency about 4 Hz). If the starter block bridge is removed again immediately after the engine starts up then the system 20 warning light flashes until the control device switches off the next time.

3.3 DIAGNOSIS FUNCTION The basis of self diagnosis is fault recognition.

All input and output signals are checked for faults. In the case of the input signals an omission of the physically sensible signal area leads to a fault being entered in the fault memory.

In the case of output signals the logical level is checked to agree with the re-measured level.

SP1427.P3C September 9, 1997 In addition in the case of the input signals a check is made for functional errors such as overlong pump switch-on times (pump cycle) unacceptable deviations between ideal and actual clutch position (clutch position sensor) comparison of engine speeds DME 1 and DME 2 check on valve flow for physically sensible range check whether during a gear change the two switching intent signals are active simultaneously ==> fault "switching intent" is detected check on LL-switch in dependence on throttle valve reciprocal monitoring of gear input and tacho speed.

Each detected fault is entered in a fault memory. The fault is rated a numerical value between 1 and 8. Number 1 means the fault current exists. Higher numbers show when the fault last occurred. On switching off the system the numerical states of all the faults not currently adjacent are increased by 1 and then stored. Number level 2 thus signifies that the fault occurred during the penultimate operating phase but is currently no longer present. A fault level between 2 and 7 is to be interpreted accordingly (eg 5: faults no longer appeared in the last 5 operating phases). Number level 8 signifies that the fault has occurred at least once since the last cancellation of the fault memory but no longer during the last 7 operating phases.

Faults which have not occurred remain unrecorded.

3.3.1 Reading the fault memory SP1427.P3C September 9, 1997 The output of the fault memory is produced through a flashing code by means of the system warning light. In order to prepare the diagnosis output the bridging plug is set to the "diagnosis" socket. The diagnosis output begins when the ignition is switched on by operating the foot brake pedal (longer than 2.5 sec).

At the beginning of the diagnosis output a light phase flashes on for 2. 5 seconds. The flashing code output of the fault recorded in the fault memory then begins. The fault code is in three parts, the first two numbers designate the type of fault (see Table 3). The third position contains the relevant fault number. The individual number pulses are separated by a short dark phase and the is individual positions through central and different fault entries by long dark phases.

After the output has run through once the warning light goes out. A new output can be triggered by operating the foot brake. During the diagnosis output the operation of the foot brake is ignored (ie no new output is started).

After pulling out the bridging plug from the "diagnosis" socket the ignition is switched on and the fault memory cancelled.

3.4 ENGINE S= DOWN During operation with extreme engagement point displacement:

when difference zero - engagement point < 3 mm or difference maximum stroke - engagement point < lmm SP142.P3C September 9, 1997 then switch off engine Note: this can only happen when the vehicle is stationary for a longer time with the gear engaged.

With software emergency running: when:

engine speed < 500 1/min and supply pressure p < 50 bar (no cable break) and foot brake operated or supply pressure p < 50 bar (no cable break) and handbrake operated and flag,engine already running" then: switch off engine Note: The link with the flag,engine already running" is necessary since otherwise the engine shut down could also be active when starting the engine.

With hardware emergency running: when engine speed < 500 1/min and foot brake or handbrake operated then switch off engine Note: if the starter were operated in the hardware emergency running (starter block bridged) then when the brake is operated the engine shut down is active. Since the signal is accepted a maximum of 3 sec by the DME then the engine starts up with a 3 sec delay.

BACKGROUND FOR ACTIVE ENGINE S=DOWN WITH EXTREME

ENGAGEMENT POINT DISPLACEMENT Problem: When driving, changes in temperatures can create situations where an unintended closing of the, SP1427.P3C September 9, 1997 1 clutch can occur as a condition of the design.

Situation 1: The vehicle is moved at high speed. The high driving speed requires a very good cooling of the hydraulic pipe. In the following the vehicle is held stationary then the hydraulic pipe heats up severely. As a result of the expansion of the brake fluid between the transducer and receiver cylinder, the transducer cylinder is moved successively in the direction of zero. Here the danger exists that in the event of particularly severe temperature increase (without driving) or when next driving off the transfer of the bore for fluid compensation (11snifting boren) in the transducer cylinder causes uncontrolled closing of the clutch.

Solution: Switch off engine as soon as the danger of an uncontrolled driving exists. Thus the clutch is closed and a fluid exchange takes place through the 'Isnifting bore,, whereby normal driving becomes possible again when restarting the engine.

Situation 2: The vehicle is brought into the disengaged state with a severely heated hydraulic pipe.

By cooling the hydraulic pipe the clutch is slowly closed. This is recognised by the engagement point adaption and moves the transducer cylinder in the clutch,opening" direction. It is now however conceivable here that the clutch path which the transducer cylinder has available is not adequate. if' SP1427.P3C september 9, 1997 the transducer cylinder is at the stop the clutch is slowly closed as a result of the cool down.

Solution: Switch off engine as soon as the transducer cylinder reaches the maximum stroke. The clutch is closed and the fluid exchange through the snifting bore can take place.

The invention is not restricted to the embodiments described and illustrated but also includes those variations which can be achieved by combining individual features or elements described or illustrated in conjunction with the various embodiments and processes. The applicant reserves the right to claim as being of inventive importance further features disclosed up until now only in the description or in the drawings.

This application is divided from application no 9415534.8 which describes and claims a motor vehicle with a device for controlling an automatic clutch mounted in the torque path between an internal combustion engine and a gearbox, wherein the control device is arranged, when the vehicle is stationary or practically stationary with a gear engaged and the engine running and with the accelerator (fuel supply measuring element) not operated, to steadily close the clutch so that at least a sufficient torque is transferred to cause the vehicle to crawl.

Also divided from application No 9415534.8 is application 9706152.7 which describes and claims a motor vehicle with an internal combustion engine and a gearbox and an automatic clutch mounted in the torque flow and at least one control device for the clutch, as well as with a hydraulic system with sender cylinder, receiver cylinder and a hydraulic line SP1427.P3C september 9, 1997 between sender and receiver cylinders, a hydraulic fluid and a device for volume compensation and a snifting bore, characterised in that the clutch is closed controlled at least from time to time and a volume compensation of the 5 hydraulic fluid is carried out.

SP1427.P3C September 9, 1997

Claims

PATENT CLAIMS

1 Motor vehicle with an automatic clutch in the torque path between an engine and gearbox and with at least one control device, such as an electronic clutch management system therefor, wherein upon failure of the system an emergency routine such as a software emergency shutdown and/or hardware emergency shutdown is activated.

2. motor vehicle as claimed in Claim 1, wherein an emergency and/or a failure is indicated.

3. Motor vehicle as claimed in Claim 1 or Claim 2, wherein an emergency and/or a f ailure is indicated by a control indicator or warning lamp.

4. Motor vehicle as claimed in Claim 3, wherein an emergency and/or a failure is indicated by a blinking light or a steady light of the control indicator.

5. Motor vehicle as claimed in any preceding claim, wherein a failure of the electronic clutch management system will be indicated on the occurrence of a sensor error, on a sensor breakdown, clutch position error, pressure drop of the hydraulic system, on simple or multiple sensor errors, on processor breakdown, on breakdown of the voltage supply, the hydraulic system or the output stages.

6. Motor vehicle as claimed in any preceding claim, wherein an error is entered in an error store, and when the error is corrected the error store is reset.

7. Motor vehicle as claimed in any prec'eding claim, wherein a processor of the control device is monitored by an SP1427. P3C September 9, 1997 external watchdog, so that in the event of a processor breakdown, a processor reset is carried out.

8. Motor vehicle as claimed in Claim 7, wherein on a processor reset, there is a switching over to a hardware emergency system.

9. Motor vehicle as claimed in any preceding claim, wherein on the occurrence of an emergency at a motor speed 10 < 300 1/min, the clutch is closed.

10. Motor vehicle as claimed in any preceding claim, wherein on the occurrence of an emergency at a motor speed > 400 1/min, the clutch position is controlled in dependence on the throttle flap angle.

11. Motor vehicle as claimed in Claim 10, wherein at small throttle flap angles the clutch is opened and at large throttle flap angles the clutch is closed.

12. motor vehicle as claimed in any preceding claim, wherein in an emergency a hydraulic pump associated with the automatic clutch is time controlled, such as cycled or switched on and off.

13. Motor vehicle as claimed in any preceding claim, wherein in an emergency the starter lock is released so that starting of the engine is blocked.

14. Motor vehicle as claimed in any preceding claim, wherein in an emergency with the system switching off, the clutch is closed.

SP1427.P3C September 9, 1997 31 -

15. Motor vehicle as claimed in any preceding claim, wherein a plausibility check takes place the sensor signals to and f rom the control device.

16. Motor vehicle as claimed in Claim 15, wherein replacement values for the sensor signals are used from the sensor errors recognised by the plausibility check.

17. Motor vehicle as claimed in Claim 16, wherein an auxiliary motor rotation is switched on upon an error of the engine rotation signal.

18. Motor vehicle as claimed in Claim 16, wherein a replacement value rl,; is introduced upon an error = 0 min is of the gearbox input rotation signal nG,,.

19. Motor vehicle as claimed in Claim 16, wherein upon an error of the tacho rotation signal n, a replacement value n. = 0 is introduced.

20. Motor vehicle as claimed in Claim 16, wherein a replacement value a,,, , = S is introduced upon an error of the throttle flap signal a,,,,.

21. Motor vehicle as claimed in any preceding claim, wherein all input signals and/or output signals of the control device are tested for errors.

22. Motor vehicle as claimed in Claim 21, wherein a departure from the physically sensible signal area of the input signal leads to an error entry in the error store.

23. Motor vehicle as claimed in Claim 21 or Claim 22, wherein the logical level of the output signal is checked for agreement with a pre-determined level.

SP1427.P3C Septernber 9, 1997

24. Motor vehicle as claimed in any preceding claim, wherein error signals resulting from failures are stored in an error store with a plurality of counter values.

25. Motor vehicle as claimed in Claim 24, wherein upon currently appearing errors, the error store is assigned a first counter value 1.

26. motor vehicle as claimed in any one of Claims 23 to 25, wherein the contents of the error store can be displayed.

SP1427.P3C January 5, 1998

26. Motor vehicle as claimed in Claim 24 or Claim 25, wherein upon the presence of an error and on switching off of the system, the counter state is incremented and stored.

27. Motor vehicle as claimed in any one of Claims 24 to 26, wherein the contents of the error store can be displayed.

28. Motor vehicle as claimed in any one of the preceding claims, wherein during operation of the vehicle at extreme engagement point slipping, for example, at a difference maximum stroke - engagement point < 1 mm or at a difference lower point - engagement point < 3 mm the engine is switched off.

29. Motor vehicle as claimed in any preceding claim, wherein in the case where the sender cylinder has reached its maximum stroke, the engine is switched off, the clutch is closed and a fluid exchange takes place through the snifting tube.

SP1427.P3C September 9, 1997 Amendments to the clakns have bow filed as follows 3'2:p - PATENT CLAIMS 1. Motor vehicle with an electronic clutch management system comprising an internal combustion engine, a gearbox, an automatic clutch in the torque path of the vehicle and at least one control device for controlling the automatic clutch, wherein upon an emergency or a failure of the system a software emergency routine and/or a hardware emergency routine is activated, wherein an emergency or failure of the system will be indicated on the occurrence of a sensor error, on a sensor breakdown, clutch position error, pressure drop of the hydraulic system, on simple or multiple sensor errors, on processor breakdown, on breakdown of the voltage supply, the hydraulic system or the output stages, 15 wherein an error is entered in an error store. 2. Motor vehicle as claimed in Claim 1, wherein an emergency and/or a failure is indicated. 20 3. Motor vehicle as claimed in Claim 1 or Claim 2, wherein an emergency and/or a failure is indicated by a control indicator or warning lamp. 4. Motor vehicle as claimed in Claim 3, wherein an 25 emergency and/or a failure is indicated by a blinking light or a steady light of the control indicator. 5. Motor vehicle as claimed in any preceding claim, wherein an error is entered in an error store, and when the 30 error is corrected the error store is reset.

6. Motor vehicle as claimed in any preceding claim, wherein a processor of the control device is monitored by an external watchdog, so that in the event of a processor breakdown, a processor reset is carried out.

SP1427.P3C January 5, 1998 7. Motor vehicle as claimed in Claim 6, wherein on a processor reset, there is a switching over to a hardware emergency system.

8. Motor vehicle as claimed in any preceding claim, wherein on the occurrence of an emergency at a motor speed < 300 1/min, the clutch is closed.

9. Motor vehicle as claimed in any preceding claim, wherein on the occurrence of an emergency at a motor speed > 400 1/min, the clutch position is controlled in dependence on the throttle flap angle.

10. Motor vehicle as claimed in Claim 9, wherein at small throttle flap angles the clutch is opened and at large throttle flap angles the clutch is closed.

11. Motor vehicle as claimed in any preceding claim, wherein in an emergency a hydraulic pump associated with the automatic clutch is time controlled, such as cycled or switched on and off.

12. Motor vehicle as claimed in any preceding claim, wherein in an emergency the starter lock is released so that starting of the engine is blocked.

13. Motor vehicle as claimed in any preceding claim, wherein in an emergency with the system switching off, the clutch is closed.

14. Motor vehicle as claimed in any preceding claim, wherein a plausibility check takes place the sensor signals to and from the control device.

SP1427.P3C January 5, 1998 7J,4, 15. Motor vehicle as claimed in Claim 14, wherein replacement values for the sensor signals are used from the sensor errors recognised by the plausibility check.

16. Motor vehicle as claimed in Claim 15, wherein an auxiliary motor rotation is switched on upon an error of the engine rotation signal.

17. Motor vehicle as claimed in Claim 15, wherein a replacement value rl,,,t = 0 min' is introduced upon an error of the gearbox input rotation signal nG, 18. Motor vehicle as claimed in Claim 15, wherein upon an error of the tacho rotation signal n, a replacement value n. = 0 is introduced.

19. Motor vehicle as claimed in Claim 15, wherein a replacement value %, = 5 is introduced upon an error of the throttle flap signal a,,,,.

20. Motor vehicle as claimed in any preceding claim, wherein all input signals and/or output signals of the control device are tested for errors.

21. Motor vehicle as claimed in Claim 20, wherein a departure from the physically sensible signal area of the input signal leads to an error entry in the error store.

22. Motor vehicle as claimed in Claim 20 or Claim 21, wherein the logical level of the output signal is checked for agreement with a pre-determined level.

23. Motor vehicle as claimed in any preceding claim, wherein error signals resulting from failures are stored in an error store with a plurality of counter values.

SP1427.P3C January 5, 1998 5(0 24. motor vehicle as claimed in Claim 23, wherein upon currently appearing errors, the error store is assigned a first counter value 1.

25. Motor vehicle as claimed in Claim 23 or Claim 24, wherein upon the presence of an error and on switching off of the system, the counter state is incremented and stored.