CONTROL DEVICE FOR AUTOMATIC TRANSMISSION

摘要

PROBLEM TO BE SOLVED: To prevent the lowering of a release side hydraulic pressure in engagement shifting between frictional engagement elements of an automatic transmission. SOLUTION: A release valve 24 for changing over a feed passage of the hydraulic pressure to a control valve is disposed in an upstream of the oil passage of the control valve 25 for controlling the hydraulic pressure of a first frictional engagement element B-3, the hydraulic pressure from a first oil passage 201e capable of feeding hydraulic pressure in attaining a first speed gear stage via the release valve and a second oil passage 201b capable of feeding the hydraulic pressure in attaining the first and the second speed gear stage is made to possible via the release valve, and only when shifting from the first speed gear stage to the second speed gear stage, the feeding of the hydraulic pressure to the control valve 25 is changed over the second oil passage 201b. This constitution can eliminate changeover of the feed oil passage to the control valve 25 in shifting from the first speed gear stage to the second speed gear stage so a to prevent the lowering of the hydraulic pressure in releasing the first frictional engagement element B-3 with the hydraulic pressure of a second frictional engagement element B-2 set to an original pressure.