Jatco Corporation

Goh Endo

Osamu Sato

Masami Suzuki

Yuuji Saitou

Seiji Okazaki

In gear shift control apparatus and method for an automatic transmission, a first frictional engagement element is, in turn, released, a second frictional engagement element is, in turn, engaged to perform the gear shift to another gear stage, a command hydraulic pressure to the second frictional engagement element is temporarily reduced when a parameter indicating a degree of progress of the gear shift detected during the gear shift to the other gear stage has reached to a predetermined value representing an inertia phase finish immediate prior region at a time of an inertia phase developed during a replacement gear shift, an reduction quantity of the command hydraulic pressure is set whenever a predetermined time has elapsed on a basis of the parameter detected whenever the predetermined time has elapsed in the inertia phase finish immediate prior region to progressively reduce the command hydraulic pressure.

Gear shift control apparatus and method for automatic transmission

A hydraulic control apparatus for an automatic transmission, including a sequential shift control means for performing sequential shift control in a case where it is necessary to execute the second shift during execution of the first shift. The sequential shift control includes starting reduction of hydraulic fluid pressure in the third friction element when a parameter that varies in accordance with a degree of progress of the first shift has reached a predetermined value, and performing piston stroke control that includes outputting a high hydraulic pressure command as a hydraulic fluid pressure to the second friction element when the selector valve is switched from the second position to the first position, and subsequent to completion of outputting of the high hydraulic pressure command, outputting a low hydraulic pressure command that is lower than the high hydraulic pressure command.

Hydraulic control apparatus for automatic transmission

During control of a shift of a first friction engagement element from an engaged state into a disengaged state and a shift of a second friction engagement element from a disengaged state into an engaged state for a gear shift to a first target gear from a second target gear, a desired torque capacity of the first friction engagement element is set based on an actual transmission gear ratio by interpolation from values of the desired torque capacity corresponding to at least first and second reference transmission gear ratios, wherein the first reference transmission gear ratio is a transmission gear ratio at start of an inertia phase of the shift control. When the first reference transmission gear ratio is between the actual transmission gear ratio and the second reference transmission gear ratio, the desired torque capacity is set to the value corresponding to the first reference transmission gear ratio.

Automatic transmission control apparatus and method

When it is judged that a vehicle speed detected by a vehicle speed sensor is equal to or lower than a predetermined very low value, that is, for example, 5 km/h, the hydraulic pressure applied to an engaging-side frictional element is sharply increased, sharply reduced and then held higher than a given value capable of effecting a piston stroke of a corresponding piston unit until a time when the piston stroke is completed. Upon completion of the piston stroke, the hydraulic pressure is increased to a maximum value in a time that is smaller or shorter than that set when the detected vehicle speed is higher than the predetermined very low value.

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Yokohama, Japan

Goh Endo