Hydraulic control apparatus for automatic transmission

A hydraulic control apparatus for an automatic transmission, comprising:

• a plurality of friction engagement elements;
• a plurality of hydraulic servos engaging and disengaging respectively the plurality of friction engagement elements;
• hydraulic pressure supply means for generating a predetermined hydraulic pressure, and supplying the predetermined hydraulic pressure to the hydraulic servo of the predetermined friction engagement element selected in correspondence to a speed to be achieved;
• a switching valve including an input section where the hydraulic pressure generated by the hydraulic pressure supply means is input and an output section for outputting a hydraulic pressure other than the hydraulic pressure generated by the hydraulic pressure supply means in order to supply to the predetermined hydraulic servo;
• and
• valve switching means for further switching over the switching valve in a state where there is no hydraulic pressure input to the input section, and the switching valve switches over to output the other hydraulic pressure.

A hydraulic control apparatus for an automatic transmission, comprising:

• a plurality of hydraulic servos engaging and disengaging respectively a plurality of friction engagement elements;
• a solenoid and a control valve combination that supplies the hydraulic servo of a predetermined friction engagement element selected in correspondence to a speed to be achieved with hydraulic pressure;
• and
• an apply control valve that supplies a predetermined hydraulic servo with a hydraulic pressure other than the hydraulic pressure supplied by the solenoid and the control valve combination, in the case that the solenoid and the control valve combination is put in a first unsupplied state where the solenoid and the control valve combination can not supply the hydraulic servo of the predetermined friction engagement element with hydraulic pressure, and for not supplying the predetermined hydraulic servo with the other hydraulic pressure, in the case that the solenoid and the control valve combination is put in a second unsupplied state where the solenoid and the control valve combination does not supply the hydraulic servo of the predetermined friction engagement element with hydraulic pressure.

A hydraulic control apparatus for an automatic transmission, comprising:

• a plurality of friction engagement elements;
• a plurality of hydraulic servos engaging and disengaging respectively the plurality of friction engagement elements;
• a solenoid and a control valve combination that supplies a predetermined hydraulic pressure, and supplying the predetermined hydraulic pressure to the hydraulic servo of the predetermined friction engagement element selected in correspondence to a speed to be achieved;
• a switching valve including an input section where the hydraulic pressure supplied by the solenoid and the control valve combination is input and an output section for outputting a hydraulic pressure other than the hydraulic pressure supplied by the solenoid and the control valve combination in order to supply to the predetermined hydraulic servo;
• and
• a valve switching solenoid that further switches over the switching valve in a state where there is no hydraulic pressure input to the input section, and the switching valve switches over to output the other hydraulic pressure.