| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control device for an automatic transmission which prevents a hydraulic switch for detecting an oil pressure of an engagement element from being affected by oil vibration of a line pressure. SOLUTION: In the automatic transmission, a solenoid pressure is made to act on one end side of a spool of a pressure regulating valve 45, and a second brake pressure, and an oil pressure passing a change-over valve 46 and urging force of a spring 53 are made to act on the other end side of the spool. A pilot pressure is made to act on one end side of a spool of the change-over valve 46 and a solenoid pressure and a spring force are made to act on the other end side of the spool. When the solenoid pressure is equal to or higher than a predetermined value, that is, when a second brake B2 is under engagement, the pressure regulating valve 45 supplies to the second brake B2 the second brake pressure which is determined by regulating the line pressure by Hi-gain. Therefore, when the second brake B2 is engaged, since the second brake pressure in which the oil vibration is attenuated by regulating the line pressure is supplied to the second brake B2, the line pressure containing large oil vibration does not directly act on the hydraulic switch 50, so that the durability of the hydraulic pressure can be improved. COPYRIGHT: (C)2005,JPO&NCIPI |
