Patent ID: 8465396
Filing Date: 2013-06-18
Classification: F16H,Y10T

Abstract:
1. An automatic transmission which includes a planetary gear and a plurality of friction elements and realizes a plurality of gear positions by changing engaged states of the plurality of friction elements, the plurality of friction elements including a reverse friction element which is engaged when a selector is in an R position and released when the selector is in a D position in which an engine brake is not activated, the automatic transmission comprising: a hydraulic pressure source; a switching valve and a manual valve arranged between the hydraulic pressure source and the reverse friction element and adapted to switch oil passages in conjunction with a selector operation, the switching valve being switched later than the manual valve; a first oil passage connecting the reverse friction element and the switching valve; a second oil passage connecting the hydraulic pressure source and the manual valve; a third oil passage connecting the switching valve and the manual valve; and a control unit which controls the switching of the switching valve; wherein: the manual valve disconnects the second and third oil passages when the selector is in the D position or the N position and causes the second and third oil passages to communicate when the selector is in the R position; and the control unit switches the switching valve to disconnect the first and third oil passages when the selector is in the D position or the N position and a vehicle equipped with the automatic transmission is driving at a vehicle speed equal to or lower than a predetermined vehicle speed.