Interrelated power delivery controls – including engine control – Transmission control – With clutch control
Patent
1998-05-22
2000-08-15
Bonck, Rodney H.
Interrelated power delivery controls, including engine control
Transmission control
With clutch control
74335, 192 358, 192 524, B60K 4128, B60K 4122
Patent
active
061028290
DESCRIPTION:
BRIEF SUMMARY
This invention relates to gear change mechanisms and associated equipment used in automobiles.
In our prior patent application WO 95/02775 we have described a gear change mechanism and associated clutch and throttle mechanisms whereby gear changes may be effected automatically upon the driver initiating a gear change operation.
The present invention is concerned with providing an improved and modified gear change mechanism and associated mechanisms. However the mechanisms to be described may find application independently of the arrangement described in said earlier application.
In one aspect the invention provides a vehicle gear change mechanism comprising a prime mover, a change speed gearbox, clutch means through which drive is transmitted from the prime mover to the gearbox, a gearbox actuator for effecting a change of gear ratio to the gearbox, the actuator being power operated, and control means for controlling the operation of the actuator in accordance with a selected change of gear ratio, the control means controlling the operation of the actuator such that the force supplied by the actuator to effect a gear change is varied so that over part of the movement of the actuator during which gear engagement takes place, the force is less than during another part of the movement of the actuator.
By this means the gear engagement may be achieved more smoothly and with less likelihood that the gearbox will become damaged, that jerky gear changes will be made, and that the gear engagement will be unduly forced. In particular the force applied during engagement of a gear is reducible over that part of the gear change in which the synchromesh is being engaged. The arrangement is intended to assist in enabling better equality of gear speeds to be achieved during engagement.
Preferably the actuator is hydraulically operated and the control means controls the operation of the operator according to the hydraulic pressure applied to the actuator whereby the hydraulic pressure applied to the actuator, and hence to operate a gear change, is reduced during gear engagement, the position of the actuator being monitored by the control means.
Conveniently the supply of hydraulic pressure fluid to the actuator is interrupted during gear engagement.
In one arrangement supply means for supplying hydraulic fluid to the actuator includes a control valve and a hydraulic accumulator or other compliant or yieldable means located downstream of the control valve, and a pressure sensor downstream of the control valve, whereby on interrupting the hydraulic supply by operation of the control valve a reduced pressure is available from the hydraulic accumulator, the valve being opened and closed with reference to the pressure sensed by the pressure sensor, the position of the actuator, and in accordance with the control means.
It will be appreciated that downstream of the valve the fluid pressure will decay, when the valve is not open, due to leakage past seals etc., or when movement of the actuator takes place, thereby giving rise to the reduced pressure.
Alternatively, the means for supplying hydraulic fluid to the actuator includes a pressure regulator to selectively reduce the hydraulic pressure downstream of the regulator which is applied to the actuator.
In another aspect of the invention the clutch means is hydraulically operated and the control means effects operation of the clutch means during a gear change selection, the clutch means being hydraulically powered towards a clutch disengaged position and biased towards an engaged position, movement towards an engaged position being controlled by the control means through a pressure release valve.
An object of this arrangement is to be able to eliminate the need for manual operation of the clutch whereby automatic gear changes can be effected using an automatic clutch.
The key to successful clutch engagement is to replicate a smooth manually operated clutch release and, according to the invention, this is achieved by control means controlling operation of a pressure release valv
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patent: 5191804 (1993-03-01), Genise
patent: 5697251 (1997-12-01), Lorriette et al.
patent: 5722297 (1998-03-01), Tischer et al.
Patent Abstracts of Japan vol. 9 No. 311 publication No. JP60146953 Feb. 8, 1985 Gear Shift Control for Automatic Car Speed Changer.
Broadbent Roland J.
Muddell Giles D.
Bonck Rodney H.
Prodrive Holdings Limited
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