192 clutches and power-stop control – Transmission control and clutch control – Interrelated
Patent
1993-07-09
1995-06-27
Bonck, Rodney H.
192 clutches and power-stop control
Transmission control and clutch control
Interrelated
477 84, 477180, F16D 4806, B60K 4122
Patent
active
054272157
DESCRIPTION:
BRIEF SUMMARY
This invention is concerned with the control of the clutch in a vehicle which has a semi automatic or fully automatic transmission.
Patents GB 2 088 007, and GB 2 079 888 describe means for controlling a vehicle clutch when taking up from rest which use the concept of a closed loop control whereby the engine speed is controlled so as to equal a pre-calculated reference speed by varying the degree of engagement of the clutch. By this means it is possible to ensure that the vehicle moves off smoothly from rest, either gently or vigorously according to the drivers wishes, whether the vehicle is on the flat or mounting a hill.
Patent application WO 89/10282 describes a control system which includes control of the clutch during a gear change, and patent application WO 89/03318 describes the control of the clutch during normal driving in a manner which eliminates driveline shock due to sudden changes of throttle. Both of these patent applications describe systems which calculate a degree of engagement of the clutch intended to give an optimum slip torque, but due to inherent variability in the performance of the friction material of the clutch facing the final effect may be slightly too harsh or too soft. It is the object of the present invention to extend the concept of the closed loop control of the first mentioned patents to the control of the clutch in general driving in non-takeup gears to improve the smoothness of the ride during gear changes, sudden throttle manipulations and other disturbances.
Other systems are known in which the engine speed is compared with the driven plate speed directly, and which then attempt to set this difference at a finite value such as 150 rpm. It is a further advantage of the system here described that by comparing engine speed with a correctly chosen reference the difference should be close to zero, which means that the scaling of the parameter representing the difference can be more advantageously chosen, enabling the control system to work with greater accuracy. If the system is implemented in a microprocessor the calculations within the speed loop need to be repeated at a greater frequency than other calculations. The design of the loop so that error is near zero without further calculations is of assistance in minimising the calculation that has to be done within the loop.
The present invention provides a clutch control system for a vehicle having a clutch actuation means, a transmission and an engine, the system comprising sensing means including an engine speed sensor for producing an engine speed signal variable with the speed of the engine and a clutch position sensor for producing a clutch position signal variable with the state of engagement of the clutch; reference signal generating means for generating a reference signal; and a control means operable in a first mode wherein the control means compares the reference signal with the engine speed signal and operates the clutch actuation means so that the engine speed signal tends to approach the reference signal, and a second mode wherein the clutch actuation means is not controlled by a reference signal, the control means being arranged to switch between the two modes in response to signals from the sensing means.
Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic representation of a clutch control system according to the invention;
FIG. 2 is a graph showing variation in time of various parameters within the system of FIG. 1 during a gear change;
FIG. 3 is a graph showing variation in time of various parameters within the system of FIG. 1 following a sudden demand for torque by a driver;
FIGS. 4a and 4b are graphs showing variation in time of various parameters within the system of FIG. 1 when the driven plate speed exceeds a maximum safe engine speed; and
FIG. 5 is a graph showing variation in time of various parameters within the system of FIG. 1 when the engine speed falls below a set value.
Ref
REFERENCES:
patent: 4413714 (1983-11-01), Windsor
patent: 4558772 (1985-12-01), Grimes et al.
patent: 4623052 (1986-11-01), Watanabe et al.
patent: 4646891 (1987-03-01), Braun
patent: 4674609 (1987-06-01), Sturges et al.
patent: 4712658 (1987-12-01), Grunberg
patent: 4800497 (1989-01-01), Koori et al.
patent: 4874070 (1989-10-01), Nellums et al.
Automotive Products plc
Bonck Rodney H.
Germain Lee A.
Milliken Paul E.
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