Clutch-to-clutch shifting in automatic transmission

In a shift control for an automatic transmission drivingly coupled with an engine, the automatic transmission including an input shaft drivingly coupled with the engine, an apply element, and a release element, the automatic transmission effecting shifting by initiating engagement of the apply element during release of the release element, a method of controlling engagement of the apply element, comprising the steps of:

• determining a revolution speed of the input shaft and generating a revolution speed indicative signal indicative of said revolution speed detected;
• determining a derivative of said input shaft revolution speed indicative signal and generating an actual derivative indicative signal indicative of said derivative determined;
• repeating increment of a target derivative value after a first moment when said actual derivative indicative signal fails to be greater than a first predetermined value, said target derivative value being increased from a second predetermined value that is lower than said first predetermined value;
• executing an open loop control after said first moment to a second moment when said actual derivative indicative signal fails to be greater than said target derivative value, said open loop control being such that a hydraulic fluid pressure applied to the apply element is increased toward a predetermined hydraulic pressure level at which the apply element is in a slidable engagement state;
• keeping said target derivative value unchanged for a predetermined period of time after said second moment and resuming increment of said target derivative value after elapse of said predetermined period of time;
• and
• executing a feedback control after said second moment, said feedback control being such that the hydraulic fluid pressure applied to the apply element is controlled in such a direction as to decrease a deviation of said actual derivative indicative signal from said target derivative value toward zero.

In a shift control for an automatic transmission drivingly coupled with an engine, the automatic transmission including an input shaft drivingly coupled with the engine, an apply element, and a release element, the automatic transmission effecting shifting by initiating engagement of the apply element during release of the release element, a method of controlling engagement of the apply element, comprising the steps of:

• determining a revolution speed of the input shaft and generating a revolution speed indicative signal indicative of said revolution speed detected;
• determining a derivative of said input shaft revolution speed indicative signal and generating an actual derivative indicative signal indicative of said derivative determined;
• scheduling a target derivative value variable with respect to time;
• executing an open loop control after a first moment when said actual derivative indicative signal fails to be greater than a first predetermined value to a second moment when said actual derivative indicative signal fails to be greater than said target derivative value, said open loop control being such that a hydraulic fluid pressure applied to the apply element is increased toward a predetermined hydraulic pressure level at which the apply element is in a slidable engagement state;
• and
• executing a feedback control after said second moment, said feedback control being such that the hydraulic fluid pressure applied to the apply element is controlled in such a direction as to decrease a deviation of said actual derivative indicative signal from said target derivative value toward zero.

A method of a shift control for an automatic transmission drivingly coupled with an engine, the automatic transmission including an input shaft drivingly coupled with the engine, an apply element, and a release element, the automatic transmission effecting shifting by initiating engagement of the apply element during release of the release element, the method comprising the steps of:

• determining a revolution speed of the input shaft and generating a revolution speed indicative signal indicative of said revolution speed detected;
• determining a derivative of said input shaft revolution speed indicative signal and generating an actual derivative indicative signal indicative of said derivative determined;
• executing a first feedback control wherein a hydraulic fluid pressure applied to the release element is controlled in such a direction as to reduce a deviation between said actual derivative indicative signal and a first predetermined value toward zero;
• executing increment of a hydraulic fluid pressure applied to the apply element until a first moment when said actual derivative indicative signal fails to be greater than a second predetermined value that is less than said first predetermined value;
• repeating increment of a target derivative value after said first moment, said target derivative value being increased from a third predetermined value that is less than said second predetermined value;
• executing an open loop control after said first moment to a second moment when said actual derivative indicative signal fails to be greater than said target derivative value, said open loop control being such that hydraulic fluid pressure applied to the apply element is increased toward a predetermined hydraulic pressure level at which the apply element is in a slidable engagement state;
• keeping said target derivative value unchanged for a predetermined period of time after said second moment and resuming increment of said target derivative value after elapse of said predetermined period of time;
• and
• executing a feedback control after said second moment, said feedback control being such that the hydraulic fluid pressure applied to the apply element is controlled in such a direction as to decrease a deviation of said actual derivative indicative signal from said target derivative value toward zero.