Hydraulic pressure control apparatus for automatic transmission

摘要

A structure in which a hydraulic-pressure control applied pressure for controlling each engagement element of an automatic transmission is realized by using an electric signal such that combinations of engagement which encounter a tie-up in case of a failure of the signal lead to interlocking are inhibited to prevent deterioration in the durability of each engagement element. An automatic transmission incorporates a planetary gear transmission mechanism using selective engagement of at least five engagement elements to realize six gear ratios, and a hydraulic-pressure control apparatus for controlling the engagement element of the transmission mechanism. Valves (75,76,78) are provided which inhibit combinations of engagement of two or more engagement elements of the five engagement elements for interlocking the transmission mechanism.