Automatic transmission control device

An automatic transmission for use in an automobile having a throttle valve, comprising:

• a rotatable engine shaft;
• a rotatable output shaft;
• a plurality of friction engaging devices disposed between the engine shaft and the output shaft to control gear ratios;
• means for determining whether a power-on down shift operation is from a one stage upper gear or whether the power-on down shift operation is from at least a two stage upper gear;
• and
• control means for controlling engagement and disengagement of each of the friction engaging devices to effect power-on down shift operations during which an engagement side friction engaging device is caused to engage while a disengagement side friction engaging device is caused to disengage, said control means changing a time when the engagement side friction engaging device begins to engage so that when the means for determining determines that the power-on down shift operation is from a one stage upper gear the engagement side friction engaging device begins to engage after a first time and so that when the means for determining determines that the power-on down shift operation is from at least a two stage upper gear the engagement side friction engaging device begins to engage after a second time that is different from said first time.

An automatic transmission comprising:

• an engine shaft which is rotatable at a rotational speed;
• an output shaft which is rotatable at a rotational speed;
• a plurality of friction engaging devices disposed between the engine shaft and the output shaft to control gear ratios;
• and
• control means for controlling engagement and disengagement of each of the friction engaging devices so that during a power-on down shift operation a rotating engagement side friction engaging device is caused to engage while a disengagement side friction engaging device is caused to disengage, said control means including means for synchronizing the rotational speed of the engine shaft with the rotational speed of the engagement side friction engaging device during a power-on down shift operation by selecting a time when the engagement side friction engaging device begins to engage after the disengagement side friction engaging device has become disengaged, said means for synchronizing selecting the time when the engagement side friction engaging device begins to engage on the basis of the gear ratio from which the power-on down shift operation is being made and the gear ratio to which the power-on down shift operation is being made.