Patent ID: 9746072
Date: 2017-08-29
CPC Classifications: F15B,F16H

Claim:
1. An oil pressure control device that controls a supply pressure of oil supplied to an oil pressure chamber of a friction element of an automatic shift for a vehicle, the friction element having a piston that defines the oil pressure chamber and that is able to move by the supply pressure, a return spring that presses the piston against the supply pressure, and a first engagement board and a second engagement board engaged with or disengaged from each other by the piston between a non-engagement state and a non-sliding engagement state via a sliding engagement state, the oil pressure control device comprising: an electromagnetic valve that controls the supply pressure using a spool which reciprocates according to an energizing amount; and a control part that controls the energizing amount based on an instruction value of the supply pressure, wherein the control part defines a first oscillatory wave part in which the energizing amount is controlled by superimposing a first waveform with a first frequency on a second waveform with a second frequency higher than the first frequency during a first period while in the sliding engagement state and an instruction value of the supply pressure are kept constant, and the first oscillatory wave part controls the spool to reciprocate with the first frequency and a first amplitude which are changeable according to a driving condition of the vehicle during the first period while in the sliding engagement state and the instruction value of the supply pressure are kept constant.