Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Katsuhiro Hatta

Kenjiro Fujita

Katsutoshi Usuki

Toshitaka Naruse

Takeo Hiramatsu

Shigeyuki Yoshida

Yasuhiro Nakajima

Yuichi Tanaka

Shift control method for an automatic transmission

A speed change control apparatus for an automatic transmission includes a transmission control unit for controlling gear-changing. The control unit discriminates a fluid temperature/rotational speed zone based on the hydraulic fluid temperature and the engine speed at the start of gear-changing, and detects a time period from the end of dead-stroke elimination of an engagement-side hydraulic clutch to the start of actual gear-changing. In the case that a condition for executing learning correction is satisfied and if a time period from the end of the dead-stroke elimination to the start of the actual gear-changing is longer than an upper limit, the control unit increases a learning-correction time with which a dead-stroke-elimination time for the discriminated temperature/speed zone is calculated. The learning-correction time is decreased if such a time period is shorter than a lower limit. By carrying out the learning correction for various temperature/speed, occurrences of degraded shift response and shift shocks resulting from the presence of individual difference of the automatic transmission and an increase or decrease in the engine speed or fluid temperature can be prevented.

Speed change control apparatus for an automatic transmission

Speed change control method for an automatic transmission

A speed change control apparatus of an automatic transmission has a transmission control unit. When determining a fault of a power-on/off determining section on the basis of engine load information from an engine control unit, the transmission control unit controls an oil pressure controller by regarding an engine as being in a power-on state in upshifting and by regarding the engine as being in a power-off state in downshifting. As a result, in either of upshifting and downshifting, the moment when a disengagement-side friction element of the transmission begins to slip and the moment when an engagement-side friction element is engaged are made proper. This makes it possible to surely prevent undesired rise in the engine rotation during the speed change in upshifting and inability in speed change in downshifting, which are caused by a fault of the power-on/off determining section.

During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while a higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nt)' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)' coincides with the change rate (Nir)', and also the transmission torque through the lower-speed clutch is feedback-controlled such that the change rate (Nt)' coincides with the change rate (Nia)', thereby carrying out downshift.

Method and apparatus for speed change control of an automatic

During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while a higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nt)' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)' coincides with the change rate (Nir)'. Further, the transmission torque through the lower-speed clutch is feedback-controlled such that the change rate (Nt)' coincides with the change rate (Nia)', thereby carrying out downshift.

Method and apparatus for speed change control of an automotive automatic

During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nia)' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)' coincides with the change rate (Nir)'. Further the transmission torque through the lower-speed clutch is feedback-controlled such that the change rate (Nt)' coincides with the change rate (Nia)', thereby carrying out downshift.

A speed change control and apparatus of an automotive automatic transmission causes a turbine rotational speed to change toward a synchronous rotational speed associated with a desired gear stage by engaging a connection-side clutch while disengaging a release-side clutch, to thereby carry out gear-changing. To reduce a speed change shock, a speed change time is rendered stabilized irrespective of vehicle running state, by carrying out feedback control such that the time-dependent change rate (Ns)' of a rotational speed difference between clutch plates and clutch discs of the connection-side clutch becomes equal to a target slip rotational speed change rate (Ni)'.

Speed change control apparatus and method of an automotive automatic

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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Uji, Japan

Katsuhiro Hatta