Line pressure controller for automatic transmission

Claim 1

A line pressure controller for an automatic transmission having a hydraulic pressure supply circuit for supplying line pressure to frictional engaging elements which are arranged to be engaged/disengaged so as to change the speed; and regulation means for regulating said line pressure, said controller comprising: load detection means for detecting the engine load; start detection means for detecting the start of the speed change operation performed in said automatic transmission; completion detection means for detecting the substantial completion of said speed change operation performed by said automatic transmission; time supervisory means which receives the output from said completion detection means for supervising a predetermined lapse of time period after said substantial completion of said speed change operation has been detected; and first and second control means for compensating/controlling said line pressure, wherein said first control means receives the output from said completion detection means and from said time supervisory means so as to control said regulation means in such a manner that said line pressure is lowered after said predetermined lapse of time period from the start of the operation for changing the engaging state of said frictional engagement elements to said substantial completion of said speed change operation; and said second control means receives the output from said completion detection means, from said time supervisory means and from said load detection means so as to control said regulation means in such a manner that said line pressure lowering control performed by said first control means is cancelled and said line pressure is raised if said engine load has been enlarged by a predetermined value after said predetermined lapse of time after said substantial completion of said speed change operation.