摘要:
A speed change control method and apparatus for a vehicular automatic transmission having a first-speed clutch for establishing a first speed and a second-speed clutch for establishing a second speed, includes subjection of at least a duty ratio Dr of a second-speed solenoid valve for supplying oil pressure to the second-speed clutch to feedback control, so that the first-speed clutch is engaged while disengaging the second-speed clutch. This thereby increases a turbine rotational speed Nt toward the first-speed synchronous rotational speed. Further, an upper limit value Dmax of the duty ratio Dr is set, and the duty ratio Dr is subject to feedback control within a resultant duty ratio range. This thereby prevents the duty ratio Dr from being set at an excessive value caused by a delay in the rise of the oil pressure. As a result, even if a depression of an accelerator pedal is suddenly increased during a downshifting process, an interlock problem can be prevented, thereby ensuring smooth speed change.
摘要:
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.
摘要:
A speed change control method and apparatus for an automotive automatic transmission includes a controller, which selects a shift pattern in which shift lines are set as a function of both throttle opening and vehicle speed when the temperature of operating oil of the transmission is higher than a predetermined temperature, and selects a shift pattern in which shift lines are set as a sole function of the vehicle speed when the operating oil temperature is lower than or equal to the predetermined temperature. The controller refers to the selected shift pattern, and determines a gear to be established, in accordance with a corresponding one or both of the vehicle speed and the throttle opening detected by sensors, to thereby reduce the frequency in occurrence of shift shock when the operating oil temperature is low.
摘要:
In a shift control method, when a speed ratio of an automatic transmission is shifted from a third speed ratio to a first speed ratio before stoppage of a vehicle, a down shift line 3-1 in a shift pattern is shifted to a high-speed side to initiate shifting under a power-OFF condition. A third brake is released by setting the duty ratio of an electromagnetic valve of the third brake at 0% to establish a free condition (neutral condition) in an output shaft of a second transmission. While the duty ratio of an electromagnetic valve of a second clutch in a first transmission mechanism is set at 0%, the duty ratio of an electromagnetic valve of a second brake is gradually increased, so that the shifting from the second clutch to the second brake is made, and the first transmission mechanism is operatively shifted from the third speed ratio to a speed ratio corresponding to the first speed ratio. Then, the third brake is engaged again upon completion of the shifting and after mechanical engagement of a one-way clutch. Consequently, it is possible to reduce shocks in shifting the speed of the vehicle.
摘要:
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.
摘要:
A shift control method for an automotive automatic transmission is provided, which reduces a shift shock particularly at the time of a skip down-shift, and shortens a required shifting time period. An electronic control unit of a shift control apparatus releases the engagement of a clutch of a subsidiary transmission mechanism and engages a one-way clutch so as to establish a gear position not used in the normal speed change when a shift command from the fifth shift position to the third shift position is issued, gradually decreasing a valve opening duty ratio of an electromagnetic valve associated with a brake of a main transmission mechanism from an initial value D.sub.HLi before this gear position is established, determines an average turbine rotation speed changing rate dD.sub.TAVE /dt from the detected turbine rotation speed (S203), and learning correction of the initial value D.sub.HLi is made if the changing rate deviates from a target range (S204-S208).
摘要:
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.
摘要:
A speed change control method for an automatic transmission, which can achieve a smooth skip downshifting even when a driver depresses an accelerator pedal slowly in kickdown. An electronic control unit 6 calculates, at the time when a predetermined time period elapses from the time when a downshifting command from a fourth speed to a third speed is outputted, a difference between the throttle valve opening degree .theta..sub.t1 at that time and the throttle valve opening degree .theta..sub.ts at the time when the downshifting command is outputted, and a change rate (.dwnarw..sub.t1)' of the throttle valve opening degree at the time when the predetermined time period elapses. If the calculated difference is larger than the threshold value .DELTA..theta. and the calculated change rate is higher than the threshold value .DELTA.(.theta.)' (S10, S11), the electronic control unit 6 outputs a command for canceling the command for downshifting from the fourth speed to the third speed, which has already been outputted (S12), and outputs a command for downshifting from the fourth speed to a second speed (S13).
摘要:
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)'.
摘要:
A speed change control method for an automatic transmission is provided, which is capable of reducing a shift shock and a required shifting time period. A skip down-shift from a first shift position to a second shift position is effected by way of a third shift position which is not used in a normal shifting. If it is determined that a difference (N.sub.TM -N.sub.T) between the present turbine rotation speed N.sub.T and the synchronous rotation speed N.sub.TM for the third shift position becomes smaller than a threshold value .DELTA.N.sub.FM during the shifting from the first shift position to the third shift position, a control for releasing a friction engaging element 23, corresponding to a releasing side speed-changing element of the third shift position, is started prior to establishment of the third shift position, whereby a time period for establishing the third shift position is shortened, so that a shift shock and a required shifting time period are reduced.