Interrelated power delivery controls – including engine control – Transmission control – With clutch control
Patent
1994-05-04
1995-10-03
Marmor, Charles A.
Interrelated power delivery controls, including engine control
Transmission control
With clutch control
477 86, 477 90, 477 99, F16H 5968
Patent
active
054547687
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a clutch system for a vehicle.
The applicant's earlier patent GB2088007 and pending PCT patent application WO92/08065 describe clutch control systems for achieving progressive engagement of a vehicle clutch to provide a smooth clutch take up from a vehicle at rest condition.
The control logic of the above clutch control systems can prove disadvantageous in a hill start situation and can result in inadvertent rolling of a vehicle parked on an incline at start up when the vehicle is left in gear to supplement, or instead of using, the parking brake. Furthermore in such systems, if the engine cannot be started due to failure or partial failure of the self starting system, the engine cannot be started by any of the commonly accepted emergency starting means such as push-starting or tow-starting.
It is an object of the present invention to provide a clutch control system which mitigates the above problems.
According to the present invention there is provided a clutch control system for a vehicle having an engine, a gearbox having plurality of gear ratios, and a clutch providing a drive connection between the engine and the gearbox, the control system comprising a clutch actuation means for controlling the state of engagement of the clutch, a control unit which receives signals from a plurality of vehicle operating parameter sensors including a gear sensor which indicates that a gear ratio is engaged in the gearbox, the control unit processing these signals to produce a command signal for operation of the clutch actuating means, and an electrical power supply circuit for the control unit, the control system being characterised in that if on activation of the electrical power supply circuit to power-up the control unit the control unit receives a signal from the gear sensor indicating that a gear ratio is engaged in the gearbox, the control unit inhibits disengagement of the clutch by the clutch actuation means.
The control unit may also be arranged to inhibit operation of an engine starter circuit of the vehicle when clutch disengagement is inhibited.
Preferably the engine starter circuit includes a starter inhibit relay which is operated to inhibit operation of the starter circuit.
The control unit preferably deactivates the starter inhibit relay on receiving a signal that neutral has been selected in the gearbox.
Preferably an engine starter circuit activation sensor is provided and the control unit commands disengagement of the clutch on receipt of a signal from the starter circuit activation sensor indicating an attempt to start the engine when a gear ratio is engaged.
For a vehicle having a gear lever for selection of the operative ratio, the gear lever is preferably provided with a load sensor which indicates to the control unit when the gear lever is moved and the control unit on receipt of a gear lever movement signal from the load sensor commands the clutch actuation means to disengage the clutch.
The invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is a schematic drawing of a control system according to the present invention, and
FIGS. 2 and 3 are block diagrams showing the logic steps used in a microprocessor of a control unit used in the control system of FIG. 1.
Referring to FIG. 1 a motor vehicle comprises an engine 10 and a gearbox 12 coupled through a clutch 14 via a gearbox input shaft 15. Fuel is supplied to the engine by a throttle 16 which includes a throttle valve 18 operated by accelerator pedal 19. The clutch 14 is actuated by a release fork 20 which is operated by a slave cylinder 22. The operative ratio of the gearbox is selected by a gear lever 24 having a load sensor 25 which senses when loads are applied to the gear lever to make ratio selections.
The clutch control system includes a series of sensors for sensing the state of the vehicle. The engine speed is monitored by an engine speed sensor 26 including a transducer which produces an engine speed signal Ve. The state of the throttl
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patent: 4671397 (1987-06-01), Asagi et al.
patent: 4807135 (1989-02-01), Tami
patent: 5005687 (1991-04-01), Kurihara et al.
patent: 5072815 (1991-12-01), Javis
Jones Charles J.
Shepherd Paul V.
Automotive Products plc
Germain Lee A.
Kwon Peter
Marmor Charles A.
Milliken Paul E.
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