Hydraulic Control System For Automatic Transmission

6. The hydraulic control system for an automatic transmission according to claim 3, wherein:

Pneumatic Drives: System Design, Modelling and Control

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  • 35. A recording medium for use in a hydraulic control system for an automatic transmission comprising an input shaft which receives power from an engine output shaft, an output shaft which is connected to vehicle wheels, a plurality offrictional engagement elements for selectively changing torque transfer from the input shaft to the output shaft between plural torque transfer paths, hydraulic servos that engage and disengage the frictional engagement elements, said hydraulic controlsystem performing an up-shift to a predetermined gear ratio by engaging a first frictional engagement element in the plurality of frictional engagement elements and disengaging a second frictional engagement element in the plurality of frictionalengagement elements, said recording medium being readable by a computer which receives input signals from a hydraulic operating means which controls at least hydraulic pressures applied to hydraulic servos for the first frictional engagement element andthe second frictional engagement element and from sensors which monitor various vehicle operating parameters and which outputs a hydraulic control signal, said recording medium comprising, encoded thereon:

    33. The hydraulic control system for an automatic transmission according to claim 1 wherein said disengagement side hydraulic controller calculates base pressures based on an absolute value of the calculated input torque.

  • The invention relates to a hydraulic control system for an automatic transmission. More specifically, it relates to a hydraulic control system which performs a clutch to clutch shift in which one frictional engagement element is engaged and ananother frictional engagement element is disengaged at the same time to effect a shift to a predetermined gear ratio.

    32. The hydraulic control system for an automatic transmission according to claim 1 wherein said predetermined value for calculated input torque is a calculated input torque corresponding to a base pressure of 0.

    Citing PatentFiling datePublication dateApplicantTitle
    EP0059427A2 *Feb 24, 1982Sep 8, 1982Nissan Motor Co., Ltd.Shift device of hydraulic control system for automatic transmission
    EP0116898A1 *Feb 8, 1984Aug 29, 1984Nissan Motor Co., Ltd.Transmission control system including select shock suppressing arrangement
    EP0133619A1 *Jul 29, 1983Mar 6, 1985Nissan Motor Co., Ltd.Line pressure control of hydraulic control system for automatic transmission
    US4563918 *Jul 29, 1983Jan 14, 1986Nissan Motor Co., Ltd.Line pressure control of hydraulic control system for automatic transmission
    US4580466 *Feb 15, 1984Apr 8, 1986Nissan Motor Co., Ltd.Transmission control system including select shock suppressing arrangement

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    A conventional hydraulic control system for an automatic transmission is described in Japanese Kokai publication Hei 6-323415. In an up-shift by a clutch to clutch shift, the hydraulic control system detects the power on state or the power offstate before the shift starts. Then, shift control is provided in accordance with one of plural predetermined control logics which correspond to the various vehicle driving states, based on the one detected vehicle driving state. In this prior arthydraulic control system, the output torque is detected by a sensor and then it is determined if the input torque of the transmission is a positive value or a negative value. When the input torque is a positive value, that is to say, when the vehicledriving state is the power on state, the shift is effected by controlling the engagement side pressure, and the disengagement side pressure is controlled so that a disengagement side frictional engagement element is disengaged at the end of a torquephase. When the input torque is a negative value, that is to say, when the vehicle driving state is the power off state, the shift is effected by controlling the disengagement side pressure, and the engagement side pressure is controlled so that theengagement side pressure is increased at the end of the shift. By these control schemes, shifts are performed smoothly without shock in the power on state and in the power off state, and a sensation of speed reduction during the power off state isavoided.

Hydraulic control system for automatic ..

Therefore, an object of the invention is to provide a hydraulic control system for an automatic transmission which uses a common control logic in both a power on state and a power off state, and which prevents both a feeling of a speed reductionin the power off state and the engine racing which otherwise occurs when the vehicle driving state is changed from the power off state to the power on state.