Hydraulic pressure control apparatus for vehicle with automatic transmission

Abstract

The invention relates to a hydraulic pressure control apparatus for a vehicle with an automatic transmission, so as to improve the restarting response of the vehicle with the automatic transmission which effectively makes use of the idling stop of an accumulator. A hydraulic pressure loop of the automatic transmission is connected with the accumulator via an electromagnetic cut valve. At the time (t1) when an engine is restarted from the idling stop, the electromagnetic cut valve is switched to the ON position, and hydraulic pressure is discharged from the accumulator to a main pressure hydraulic way, so as to compensate the hydraulic pressure of an oil pump. A stroke sensor for detection of the stroke amount of a piston of the accumulator is attached in the accumulator. When a change in the amount of the stroke is reversed from such a direction as to discharge the hydraulic pressure to such a direction as to supply the hydraulic pressure, the electromagnetic cut valve is switched to the OFF position at the time (t3). In this way, during the time period in which the hydraulic pressure from the oil pump is increased, the hydraulic pressure is not supplied to accumulator, so that the hydraulic pressure from the oil pump can be supplied to hydraulic pressure loop exclusively so as to increase the hydraulic pressure. As a result, a stroke reducing process in a clutch can be allowed to quickly proceed to thereby obtain a high response ability.

Description

technical field [0001] The present invention relates to a hydraulic control device for a vehicle equipped with an automatic transmission that performs an idling stop. Background technique [0002] An automatic transmission includes clutches and brakes (hereinafter only represented by clutches) as a plurality of engagement devices that operate by pressing friction plates with hydraulic pressure in its gear train, and realizes a plurality of shift speeds through the combination of engagement and release of the engagement devices. For example, a low clutch (LOW / C) and a high clutch (HIGH / C) are provided, and the low clutch is engaged in the first forward speed, and the low clutch is released and the high clutch is engaged in the high third speed. [0003] The clutch has an oil pressure chamber and a piston stroked by the oil pressure supplied to the oil pressure chamber. During its operation, there are the following stages: a filling stroke up to the idling interval where the p...

AI Technical Summary

Problems solved by technology

Therefore, there is a problem that it is difficult to obtain a smooth start characteristic with high responsiveness.

[0011] This can be said to be the following reason. The accumulator is in the pressure storage state only by a predetermined amount of elastic deformation of the elastic body that urges the piston, and the pressure storage state that changes every moment cannot be managed.

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