Patent ID: 9121459
Filing Date: 2015-09-01
Classification: F16D,F16H

Abstract:
1. A driving force transmitting apparatus comprising: a rotating shaft having an axial direction and being rotatable around the axial direction; a frictional engagement device including a frictional engagement unit which is disposed around the rotating shaft and which includes first and second friction members that are alternately stacked in the axial direction; a piston member that is movable in the axial direction to press the frictional engagement unit so that the first and second friction members are engaged with each other; a piston housing that contains the piston member; a piston chamber which is defined between an inner surface of the piston housing and the piston member and in which an oil pressure to move the piston member toward the frictional engagement unit is generated; an oil pressure sensor configured to detect the oil pressure of operating oil in the piston chamber; an attachment hole which opens in a back surface of the piston housing and to which the oil pressure sensor is attached such that a sensor axial direction of the oil pressure sensor extends along the back surface of the piston housing; an operating-oil receiving chamber which is provided in the piston housing and in which a detection portion of the oil pressure sensor is disposed; a bubble removing chamber to remove bubbles accumulated in the operating-oil receiving chamber, the bubble removing chamber being provided in the piston housing at a position adjacent to the operating-oil receiving chamber; and a bubble discharging groove which is connected to the bubble removing chamber and via which the bubbles are discharged.