Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Impeller-turbine type fluid circuit in series with planetary...
Patent
1991-11-22
1994-03-08
Wright, Dirk
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Impeller-turbine type fluid circuit in series with planetary...
74866, F16H 5916
Patent
active
052922880
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a speed-changing hydraulic oil pressure control apparatus of an automatic transmission for an automobile.
BACKGROUND ART
In an automatic transmission for an automobile, the output of an engine is input in a gear type transmission through a torque converter, and in the gear type transmission, the speed is changed by coupling and disconnection of transmission elements such as a clutch and a band brake.
For example, in the case where the speed is changed to the second speed from the first speed, a shift valve is changed over by a speed-changing instruction to increase the band brake pressure above a predetermined value and bring about a torque phase (the state where one pair of friction elements slip but the other pair of friction elements are completely engaged with each other). Then, the band brake pressure is further increased to transfer the torque phase to an inertia phase (the state where both of the two pairs of friction elements slip) causing a change of revolution (see FIG. 6).
At the detection of the timing of the speed change, the transfer of the phase to the inertia phase from the torque phase is detected by the start of falling of the revolution of the engine, and the hydraulic oil pressure is changed and controlled so that an optimum value of hydraulic oil pressure is obtained for each phase.
However, in this conventional apparatus, since the transfer of the phase to the inertia phase from the torque phase is detected by the start of falling of revolution of the engine and the control is performed based on the result of the detection, a problem of a delay of the response of the oil pressure arises, and the oil pressure is not changed immediately at the transfer of the phase to the inertia phase from the torque phase and the controllability is very low.
Under this background, it is a primary object of the present invention to solve the above-mentioned problem and to detect the transient state of the speed change at a proper timing while taking the response delay of the hydraulic oil pressure into consideration.
SUMMARY
In accordance with the present invention, there is provided a speed-changing hydraulic oil pressure control apparatus of an automatic transmission for an automobile, comprising a gear type transmission connected to an output shaft of an engine through a torque converter, where the transition state of the speed change is detected to control the hydraulic oil pressure of speed-changing elements in the transmission, said apparatus being comprising (a) means for detecting the output torque of the transmission, (b) means for detecting the input revolution number of the torque converter, (c) means for detecting the output revolution number of the torque converter, (d) means for estimating the input torque of the transmission from said input revolution number and output revolution number, and (e) means for detecting the transition state of the speed change from said input torque and said output torque.
The reasons for the adoption of the above-mentioned structure will now be described.
The output torque of the transmission greatly decreases from the point just before the transfer to the inertia phase from the torque phase, but such decrease is not caused in the input torque of the transmission estimated from the input revolution number and output revolution number of the torque converter. Accordingly, by comparing the input torque and output torque of the transmission, the transfer to the torque phase from the inertia phase can be detected in advance. Therefore, if the control is performed based on the result of this detection, the response delay of the hydraulic oil pressure can be sufficiently cancelled.
The transmission input torque-estimating means can be constructed by means for computing the speed ratio e of the output revolution number, or speed, Nt of the torque converter to input revolution number, or speed, Ne of the torque converter (e=Nt/Ne), means for retrieving predetermined torque ratio t and torque capacity coefficien
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Kamada Kazuki
Kashiwabara Masuo
Sekiguchi Hideki
Tanaka Yoshikazu
Japan Electronic Control Systems Co. Ltd.
Wright Dirk
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