GB2330888A

GB2330888A - Clutch control method wherein two signals are synchronized

Info

Publication number: GB2330888A
Application number: GB9819198A
Authority: GB
Inventors: Thomas Jaeger; Claudio Castro
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1997-09-04
Filing date: 1998-09-04
Publication date: 1999-05-05
Anticipated expiration: 2018-09-04
Also published as: ITMI981956A0; IT1302179B1; FR2767884A1; FR2767884B1; GB2330888B; ITMI981956A1; GB9819198D0; BR9803386A; DE19832939A1

Abstract

A clutch is controlled by a control device 26 coupled, via a data line 30 or CAN bus, to an engine control device 32 which receives signals from sensors, eg temperature sensor 34, speed sensor 36, throttle valve sensor 38 etc. These signals are fed by the engine control device 32 to the control device 26 which calculates a combustion torque signal, indicative of the torque produced by engine 2, that is stored in a memory of the control device 26 for a predetermined time delay. A signal from the speed senor 36 is relayed to the control device 26 where it is filtered, eg by a non-recursive filter, and then differentiated to produce an acceleration signal that is used to calculate dynamic torque produced by inertia masses of the engine 2. This calculated dynamic torque also has a predetermined time delay relative to the dynamic torque actually occurring. The combustion torque time delay and the dynamic torque time delay are the same, ie synchronized, so they are used in the control device 26 to calculate a control signal, representative of total torque acting at the clutch, which controls an actuator 24 of the clutch.

Description

2330888 Method for the synchronisation of at least two signals The

invention relates to a method for synchronising at least two signals of which at least a second signal has a predetermined time delay relative to a first signal wherein a control signal derived from the signals is used for controlling, regulating or adapting further processes. This relates more particularly to the operation of a controlled or regulated operation of an automated clutch 10 or an automated transmission in the drive train of a motor vehicle. The control or regulation can be an adaptive or regulation which automatically implements from values in the operating behaviour by characteristic values of the control or control deviations adapting regulation In motor vehicles the expense for electronic controls and regulations is constantly increasing. The clutch arranged in the drive train between a drive motor and gearbox, for example, is increasingly operated automatically whereby an actor operating the clutch is controlled by a control device according to the operating conditions of the vehicle. An automated disengagement and re- engagement of the clutch during a gear change, an engagement during a starting process of the vehicle from stationary or a disengagement of the clutch during a braking process when stationary is thereby controlled or regulated for example. Likewise a control or regulation of the torque transferable by the clutch to the engine torque provided by the engine can be carried out within a tolerance band or a slip regulation, thus a regulation of the difference between the drive speed of the clutch and output speed of the clutch.

Automated clutches of this kind on the one hand increase the operating comfort of motor vehicles quite considerably. On the other hand they help to reduce fuel consumption because, particularly in conjunction with automated shift transmissions, the vehicle is more frequently driven in the most favourable gear for fuel economy. The automated clutch is thereby operated in a driving mode from reasons of low energy consumption of the actor, short time requirement for operation and comfort so that it is substantially only closed so far as is necessary so that no or no inadmissibly high slip occurs. The knowledge of the engine torque acting at the clutch is advantageous for a rapid control of the clutch.

The engine torque active at the clutch is made up from the combustion torque, such as engine torque, arising through combustion of the charge in the internal combustion engine, and a dynamic torque arising in the event of speed changes of the internal combustion engine as a result of the inertia masses. The combustion torque is derived for example from at least one of the operating parameters of the internal combustion engine, such as setting of the load control member, accelerator pedal position, throttle valve position, injection time, injection angle, speed, temperature etc. The dynamic torque acting as a result of the inertia of the internal combustion engine and which plays a particular role in the slip phases of the clutch as a result of the sudden speed change of the engine, requires a determination of the speed acceleration of the engine. This value is obtained by differentiation of the engine speed signal. As a result of the roughening-up character of a differentiation a smoothing of the engine speed signal by filtering is advantageous or even necessary prior to differentiation. The time delays, which each applicable filter algorithm entails, lead when calculating the torque active at the clutch to errors which have a significant effect on the control of the torque transferable by the clutch.

The object of the invention is to provide a method which makes it possible to avoid errors in a control or regulation or with an adaptation process of for example the transmission behaviour of control or regulation paths which are caused in that of at least two signals used for control, regulating or adaptation, one is time-delayed relative to at least another. This time delay can be produced for example by filtering at least one signal by means of a filter.

This is achieved with the features of the main claim or the subsidiary claims 2 and 3. According to the invention the time stagger of the two signals is compensated in that the first signal opposite which the second signal is delayed by a predetermined time length, is delayed by the same time length so that the two signals used for producing the control signal are synchronised or of the same time.

The first signal is advantageously stored and retrieved with the predetermined time delay from the memory and then combined with the second signal.

Claims

Claim 5 characterises the way of carrying out the method according to the

invention, which is suitable for the most varied of problems, when used for controlling an automated clutch.

Claim 6 provides a further development of the method according to claim 5 in an advantageous way since the time delays conditioned by filtering and differentiation are - 4 known and accordingly the first signal or combustion torque signal can be delayed by the predetermined time length.

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

Figure 1 is a diagram of a drive train of a motor vehicle; shows the curves which indicate the delay of a calculated acceleration of the engine speed relative to the actual acceleration of the engine speed; shows the curves which illustrate the errors which result through the time delays when calculating the engine acceleration; and is a block circuit diagram showing the delay of a signal.

Figure 2 Figure 3 Figure 4 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 the gearbox 6 which in turn is connected by a Cardan shaft 8 and differential 10 to the driven rear wheels 12. The front wheels 14 of the motor vehicle are not driven in this illustrated example.

The clutch 4 is known per se in its construction and contains inter alia a clutch disc 16 which is connected ratationally secured to the crankshaft of the internal combustion engine 2, 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.

- 5 The gearbox 6 is a commercially available manual shift transmission which can be shifted by a gearshift lever 22.

construction For operating the operating lever 20 an actor 24 is provided, for example an electric step motor which is controlled by an electronic control device 26. The electronic control device 26 is known per se in its and contains a micro processor with 10 associated memory units, interfaces etc. Its input is connected to a position sensor 58 for detecting the position of the actor 24 or of the operating lever 20 so that an ideal position of the operating lever 20 and thus of the transferable clutch torque can be regulated with 15 the control device 26 with extreme accuracy.

The control device 26 is further connected by a data line 30, such as a CAN bus.to an engine control device 32 which is likewise known per se in its construction and contains a micro processor, memory devices, interfaces etc.

To the inputs of the engine control device 32 are supplied the operating parameters of the internal combustion engine, for example the 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. The outputs 40 of the control device 32 control the operation of the internal combustion engine, such as ignition timing, injection amount, exhaust discharge rate etc.

As already explained it is necessary for a suitable control or regulation. of the clutch 4 to know the torque acting from the engine on the clutch 4. An ideal position of the clutch or operating lever 20 is calculated from this torque in the control device 26 and can depend where applicable on further parameters such as engaged gear, wheel speed, clutch slip etc and determines the operating lever 20 and thus the torque transferable by the clutch.

In order to obtain the required information the control device 26 is connected by the data line 30 to the engine control device 32. The data required to calculate the combustion torque produced by the internal combustion engine 2 as a result of combustion, such as the position of the throttle valve and speed or a signal proportional to the engine torque or a signal representing same are supplied to the engine control device 26 through the data line 30. Particularly in the case of sudden speed changes the dynamic torque produced by the inertia masses of the internal combustion engine and which have to be added to the combustion torque when decreasing speed and subtracted from the combustion torque when increasing speed, cannot be disregarded.

In order to calculate the speed acceleration dw/dt of the engine the engine speed signal detected by the speed sensor 36 and sent through the data line 30 to the control device 26 is first filtered or smoothed. For f iltering and subsequent diff erentiation of the signal it is possible to use for example a time-discrete, non-recursive filter. A compensating straight line which is optimised according to the method of the smallest error square is thereby placed for example by four measuring points. As a result of the data rate of the data line 30 the engine speed signal is only renewed every 20 ms when using a CAN bus. From the rise in the compensating straight lines it is possible to determine the change in the engine speed dn per unit time dt (control interrupt 10 ms).

7 The following equation is produced with the said values:

dn = [3rl,,.,(t)-3n,,t(t-3dt) +rl,,.,(t-dt)-rl,,,.t(t-2dt)1/20 dw/dt =(dn/dt)(27r/60)=dn/dt1047/100.

The maximum swivel time of the nonrecursive filter is produced from the time intervals between the input speed signals considered. If in the input speed signal n.., great changes in speed occur then as a result of the filtering a time displacement occurs of the calculated speed acceleration relative to the actual speed acceleration.

This situation is shown in Figure 2 where the time is given on the abscissa and the speed or speed acceleration is given on the ordinate.

The solid curve shows the speed path of the internal combustion engine wherein the case illustrated is for example changing down. The dashed curve represents the calculated speed acceleration. The dotted curve represents the actual speed acceleration. As can be seen, a time delay of about 50 ms exists between the calculated and actual speed accelerations.

This time displacement of the calculated speed acceleration relative to the speed acceleration which actually occurs leads to errors when calculating the dynamic equilibrium on the engine or the torque acting on the gearbox, particularly during the slip phases. The order of this error can be 30 Nm, as shown in Figure 3.

In Figure 3 the abscissa is again the time, the left - 8 ordinate indicates the speed acceleration and the right ordinate indicates a dynamic torque. The solid curve relates to the speed acceleration and indicates the relevant difference between the calculated acceleration and the actual speed acceleration dotted curve is calculating the acceleration and combustion engine combustion engine. dynamic torque in order of 30 Nm.

speed The calculated from the dashed curve by dynamic torque D from the speed the- moment of inertia of the internal which is known in a known internal As can be seen, the error of the the illustrated example extends to the This error, as indicated is conditioned in that the calculated dynamic torque D only exists at a time which is delayed by about 50 ms from the dynamic torque actually occurring. In order nevertheless to take into appropriate account the total torque acting at the clutch from the engine for controlling or regulating or adapting characteristic lines of the operation of the clutch, the combustion torque is included with the same delay in the calculation of the control signal for the actor 24 in the control device 26. This is shown in Figure 3 which illustrates how the combustion torque calculated from the data sent from the engine control device 32 (solid curve) is delayed by 50 ms (dashed curve) and then added to the dynamic torque (dotted curve) in order to produce the overall torque which is used for operating the actor 24.

The calculations of the speed acceleration and dynamic torque depicted, for which also other algorithms can be used, as well as the delay of the combustion torque signal can take place purely by software in the control device 26. Likewise additional hardware chips known per se can be used to this effect.

Figure 4 shows a block circuit diagram 100 for explaining the delay of a signal. In block 101 the combustion torque Me(t) of the internal combustion engine is determined or retrieved from an engine control electronics, which determines this value, or for example is detected through a CAN data bus. The same applies for the engine speed n,,., in block 102. The signal of the combustion torque Me(t) is stored interim in block 103 in an intermediate memory such as RAM memory as Mspeicher (t) The following representation of the stored values thereby applies with a time delay of 40 ms with the one signal:

Mr (t-40 MS) (t - 3 Oms) peicher Mspeicher Mspeicher (t-30 ms) = M,peicher(t-20MS) mr (t20 MS) (t - 1 Oms) pei,h,r = Mspeicher M,,peicher (t-10 ms) Neicher In block 104 the speed acceleration dw/dt is determined:

dn = Dri.,,,(t) - 3n..t (t-3dt) + n.,,t(t-dt)- n.,,(t-2dt)1/20 dw/dt = (cln/dt)(27c/60) = dn/dt1047/100.

In block 105 the torque Mk (t-40ms) adjoining the clutch at 25 time point (t-40ms) is determined at:

M,(t-40ms) = M,peicher(t-40MS)-J..cc>rdw/dt with the mass moment of inertia i.c,,,,, of the engine.

In block 106 this engine torque adjoining the input part of the clutch is used again as Mk for controlling, regulating or adaptation.

1 - 10 If more than two signals are to be processed together in a further method step and which are delayed to different amounts then the method described above can be applied in that the signals are synchronised so that the signals which are delayed by lesser amount are each delayed through the intermediate memory deliberately to the maximum amount of the existing delay. Time differences are thereby compensated which arise through filtering, calculations or other measures with regard to individual signals which are then processed together.

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 process steps or sequence of process steps insofar as these refer to manufacturing, test and work processes.

12 Claims 1. Method for synchronising at least two signals of which at least a second signal has a predetermined time delay compared to a first signal, wherein a control signal derived from these signals is used for controlling, regulating or adapting further processes, characterised in that the first signal is delayed by the predetermined time delay and the control signal is derived from the delayed first signal and at least the second signal.

2. Method for synchronising two signals of which a second signal has a first predetermined time delay relative to a first signal, wherein a control signal derived from the two signals is used for controlling, regulating or adapting further processes characterised in that the first signal is delayed by the predetermined time delay and the control signal is derived from the delayed first signal and the second signal.

3. Method according to one of claims 1 to 3 characterised in that the first signal is stored and retrieved with the predetermined time delay.

4. Method according to one of claims 1 to 4 characterised in that the first signal is a combustion torque signal, such as engine torque signal derived from operating parameters of an internal combustion engine, that the second signal is a dynamic torque signal derived from speed changes in the internal combustion engine, and that the control signal derived from the delayed first signal and the second signal is a signal controlling the operation of an automated clutch.

- 13 5. Method according to claim 5 characterised in that the second signal is derived by filtering the measured engine speed signal and differentiation of the filtered engine speed signal.

6. Method for synchronising at least two signals of which at least a second signal and where applicable further signals have a predeterminable time delay compared to a first signal wherein a control signal derived from the signals is used for controlling, regulating or adapting further processes, characterised by its special configuration and method of operation according to the present application documents.

7. Method for synchronising at least two signals substantially as herein described with reference to the accompanying drawings.