LUBRICATING STRUCTURE FOR FRICTION ENGAGEMENT ELEMENT OF AUTOMATIC TRANSMISSION

摘要

In a transmission case (20) of an automatic transmission (1), a friction engagement element (CLx) is provided radially outside of a peripheral wall portion (32) of a clutch drum (30) and configured to be engaged and released in the axial direction by a piston (40), and also a piston (70) is provided radially inside of the peripheral wall portion (32) and configured to move forward and backward in the axial direction to engage and release a friction engagement element (CLz) in the axial direction. A first peripheral wall portion (321) of the peripheral wall portion (32) includes through-holes (321a) communicating a radially inside of the first peripheral wall portion (321) with a radially outside of the first peripheral wall portion (321). A through-hole (87) is provided radially inside of the piston (70) as a feed port for lubricating oil. The piston (70) includes a communication passage (79) radially passing through the piston (70) and communicating the through-hole (87) with the through-holes (321a). A larger quantity of lubricating oil is supplied through the communication passage (79) and the through-holes (321a) to the radially outside of the clutch drum (30) when the piston (70) is in an initial position in which the friction engagement element (CLz) is in a released state. Accordingly, the friction engagement element (CLx) located outside of the peripheral wall portion (32) can be sufficiently lubricated.