Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1988-03-01
1989-07-25
Wright, Dirk
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74869, B60K 4118
Patent
active
048502510
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a hydraulic control device suitable for a multiple-speed automatic transmission mounted in a motor vehicle. Specifically, the present invention relates to a so-called neutral control device which operates when a vehicle stops while a manual valve is in D range.
DESCRIPTION OF THE PRIOR ART
An automatic transmission in general, experiences so-called creeping by dragging torque generated by a torque converter when a vehicle stops while a manual valve is in D range. This means that a driver has to keep pressing the brake to hold the vehicle at a stop. This causes fatigue in a driver and fuel efficiency of an engine is deteriorated.
Under such circumstances, a control device utilizing a low torque transmission to prevent such creeping by automatically shifting to a higher speed-stage has been proposed.
Another device to prevent such creeping by disconnecting the forward clutch at the time when a vehicle stops has also been proposed (Japanese Pat. Nos. 59-34053, 57-107045). However the device which shifts to a higher speed-stage can prevent creeping under normal idling during the warm-up of the engine and due to a large load being applied, fuel efficiency is still deteriorated.
And, the device which disconnects a forward clutch requires exclusive shift valves and solenoid valves. This makes the device complicated. Furthermore, the device disconnecting the forward clutch again connects such a clutch at the start-up of the engine; however, to prevent shift shock, more accumulator(s) modulator valve(s) and solenoid valve(s) are necessary. This makes the device complicated and large; and thus, a cost-increase and a decline in reliability are inevitable.
In addition to the above, once the forward clutch is disconnected, no bridle means operates to allow the vehicle to start on even a slight slope. Accordingly, it is desirable for a creeping prevention device to incorporate a hill-stop device; however, as indicated above, this device requires additional brake(s) and shift valves, and so the overall structure of the automatic transmission will be complicated.
SUMMARY OF THE INVENTION
Considering the problems above, an object of the present invention is to provide a hydraulic control device for an automatic transmission which operates to prevent creeping by utilizing a shift valve for a high speed-stage which is free at the time when a vehicle stops, to decrease a shift shock at start-up and delay of response, and to enable a hill-stop.
Of plural shift valves, a shift valve (1) ((4-5) shift valve, for example) for a high speed-stage which is out of use during low speed running has a port (b) communicating with line pressure open to a port (g) communicating with a forward clutch hydraulic servo (C.sub.1) during forward running. And a solenoid valve (2) to operate the shift valve (1) is controlled by signals issued at the start-up and the stop of the vehicle. When the vehicle stops, the application of line pressure (P.sub.L) to forward clutch hydraulic servo (c.sub.1) ceases. When the vehicle runs, line pressure (P.sub.L) is applied to the forward clutch hydraulic servo (C.sub.1).
Furthermore, said shift valve (1) defines the following ports: a port (i) communicating with line pressure; a port (f) which communicates with a drain; and a port (e) which communicates with a brake hydraulic servo (B.sub.1) (2nd coast brake, for example) to regulate the movement of the vehicle. When the vehicle stops, line pressure (P.sub.L)is applied to the brake hydraulic servo (B.sub.1), and when the vehicle runs, line pressure in the brake hydraulic servo (B.sub.1) is drained.
In addition, the shift valve has a port (c) to which modulator pressure (M.sub.0) is applied from a modulator valve (3). The modulator valve (3) is controlled by a controlling means of the modulator valve (3) (for example, a linear solenoid throttle valve). The modulator pressure (M.sub.0) suitably modulated by the modulator valve (3) is applied to the forward clutch hydraulic servo (C.sub.1) but when the
REFERENCES:
patent: 4274307 (1981-06-01), Iwanaga et al.
patent: 4308765 (1982-01-01), Iwanaga et al.
patent: 4334441 (1982-06-01), Iwanaga et al.
patent: 4503733 (1985-03-01), Hasegawa
patent: 4603604 (1986-08-01), Nishikawa et al.
patent: 4625591 (1986-12-01), Nishikawa
patent: 4644826 (1987-02-01), Kubo et al.
patent: 4648289 (1987-03-01), Kubo et al.
patent: 4660442 (1987-04-01), Nishikawa et al.
Kuwayama Yoshinari
Miura Masakatsu
Yokoyama Fumitomo
Aisin-Warner Kabushiki Kaisha
Wright Dirk
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