Abstract: Provided is a valve timing adjustment device that suppresses slippage of an assist spring, prevents disengagement, and facilitates assembly of the assist spring. A valve timing adjustment device adjusts an opening timing and closing timing of an intake valve or an exhaust valve of an internal combustion engine. In the assist spring, the inner peripheral end portion is formed in a non-bent shape, the outermost periphery is in contact with the rib, a second winding is in contact with the inner peripheral end portion, and there is no contact between windings from the second winding to the outermost periphery.

Abstract: Provided is a valve timing adjustment device that suppresses slippage of an assist spring, prevents disengagement, and facilitates assembly of the assist spring. A valve timing adjustment device adjusts an opening timing and closing timing of an intake valve or an exhaust valve of an internal combustion engine. In the assist spring, the inner peripheral end portion is formed in a non-bent shape, the outermost periphery is in contact with the rib, a second winding is in contact with the inner peripheral end portion, and there is no contact between windings from the second winding to the outermost periphery.

Abstract: A valve timing adjustment device includes: a center bolt being bottomed cylindrical; a spool disposed in a hollow portion of the center bolt so as to be linearly movable; an oil supply path including a region that is formed inside a cylindrical wall of the center bolt and along the longitudinal direction of the center bolt; a first annular groove formed on the inner periphery of the center bolt and communicating with the oil supply path; and a second annular groove formed on the outer periphery of the spool, disposed to face the first annular groove, and communicating with the oil supply path via the first annular groove. The oil supply path is capable of selectively, communicating with either a first work port or a second work port via the first annular groove and the second annular groove depending on the position of the spool that is linearly moving.

Abstract: A VVT includes: a cylindrical case to rotate synchronously with a crankshaft; a rotor housed in the case and to rotate synchronously with a camshaft; a first cover that has a first through hole and closes one opening of the case; a second cover that has a second through hole and closes another opening of the case; a first fastening member that fixes, in a state of passing through the first through hole, the first cover and the case; and a second fastening member that fixes, in a state of passing through the second through hole, the second cover and the case.

Abstract: A case for rotating integrally with a crankshaft of an engine; a rotor housed in the case, to be rotated integrally with a camshaft of the engine by fastening the rotor coaxially to the camshaft with a center bolt; and a groove provided around an axis of the rotor on an opposite side of the rotor to the camshaft, and having an inner wall intersecting a rotation direction of the rotor are provided.

Abstract: A case for rotating integrally with a crankshaft of an engine; a rotor housed in the case, to be rotated integrally with a camshaft of the engine by fastening the rotor coaxially to the camshaft with a center bolt; and a groove provided around an axis of the rotor on an opposite side of the rotor to the camshaft, and having an inner wall intersecting a rotation direction of the rotor are provided.