Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Toshitaka Naruse

Katsuhiro Hatta

Shigeyuki Yoshida

Yuichi Tanaka

Yasuhiro Nakajima

A shift control method for an automatic transmission of an automotive vehicle comprises a preliminary stage which is executed for eliminating the play in mechanism of a low/reverse brake of the automatic transmission at a shifting, particularly at a shifting of the transmission from the neutral position to a running position when the vehicle is at rest, and an engagement stage which is executed subsequently to the preliminary stage for operating the brake substantially. In the preliminary and engagement stages, the fluid pressure supplied to the brake is controlled in accordance with the precontrol pattern and the main control pattern, respectively. The shift control method further comprises a step of correcting a factor defining the precontrol pattern such that the time required from the start of the engagement stage to the start of a substantial shifting of the automatic transmission coincides with an ideal reference time, and a step of correcting the initial value of the fluid pressure supplied to the engaging element at the start of the main control pattern such that the rate of change in the rotational speed of the input shaft of the transmission during the period from the start of the substantial shifting to the end of same coincides with an ideal reference rate.

Shift control method for an automatic transmission of an automotive

A gear shift control system according to this invention includes a throttle opening sensor, a vehicle speed sensor and a controller for delivering a shift command signal to an automatic transmission. The controller is previously stored with shift lines, which divide the respective regions of gear-shift stages, on the basis of the throttle opening and the vehicle speed. The controller delivers the shift command signal to the transmission when any of the shift lines is crossed by a shift point which is defined by the throttle opening and the vehicle speed. Taking account of the changing rate of the throttle opening, the past throttle opening, and the acceleration of the vehicle, however, the controller calculates a decision value which is indicative of the running state of the vehicle, on the basis of the fuzzy theory. When the decision value exceeds a predetermined value, the controller corrects the shift lines depending on the running state.

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Kyoto, Japan

Toshitaka Naruse