Automatic transmission control method and control apparatus, and automatic transmission system

A control apparatus for an automatic transmission, the automatic transmission comprising a plurality of friction elements for changing an operating state of a speed change mechanism depending on a vehicle driving state, wherein the automatic transmission is configured to perform a speed change by, among the plurality of friction elements, disengaging a given disengagement-side friction element and concurrently engaging other engagement-side friction element, the control apparatus comprising:

• a pre-charge device for, based on a speed change command, pre-charging operating oil to the engagement-side friction element;
• an oil pressure holding device for, after the operating oil pre-charge by the pre-charge device, holding an operating pressure at an oil pressure less than an oil pressure during the pre-charge, for a given period of time;
• and
• a pressure raising device for, after the oil pressure holding operation by the oil pressure holding device, raising the operating pressure to cause the engagement-side friction element to be engaged,
• wherein the pre-charge device, the oil pressure holding device and the pressure raising device are provided as a means to engage the engagement-side friction element during the speed change,
• and wherein the control apparatus further comprises a pre-charge period setting device for setting a period for the operating oil pre-charge by the pre-charge device, the pre-charge period setting device being configured to predict a timing at which the engagement-side friction element is to be engaged by the devices for engaging the engagement-side friction element, while actually measuring a timing at which the engagement-side friction element has been actually engaged by the devices, and set the pre-charge period to allow a difference between the timings to become smaller, wherein the pre-charge device is operable, during a next speed change, to perform the pre-charge with respect to the engagement-side friction element, for the pre-charge period set by the pre-charge period setting device.

An automatic transmission system comprising:

• a plurality of friction elements for changing an operating state of a speed change mechanism depending on a vehicle driving state;
• a hydraulic actuator for driving each of the friction elements;
• an oil pressure control circuit having an oil pressure control valve for controlling an oil pressure against the hydraulic actuator;
• an oil pressure detection device for detecting that the oil pressure against the hydraulic actuator is equal to or greater than a predetermined engagement pressure;
• and
• a control unit configured to receive an input of a signal from the oil pressure detection device, and control the oil pressure control valve, the control unit being operable:
• based on a speed change command, to control the oil pressure control valve to pre-charge operating oil to a given engagement-side friction element among the plurality of friction elements;
• after the operating oil pre-charge, to control the oil pressure control valve to hold an operating pressure at an oil pressure less than an oil pressure during the pre-charge, for a given period of time;
• and after the oil pressure holding operation, to control the oil pressure control valve to raise the operating pressure to cause the engagement-side friction element to be engaged, wherein the control unit is operable to predict a timing at which the engagement-side friction element is to be engaged, while actually measuring, based on the signal from the oil pressure detection device, a timing at which the engagement-side friction element has been actually engaged, and set the operating oil pre-charge period to allow a difference between the timings to become smaller, and wherein the control unit is operable, during a next speed change, to control the oil pressure control valve to pre-charge operating oil to the hydraulic actuator of the engagement-side friction element, for the set pre-charge period.