There is provided a variable valve timing system, including: a camshaft rotatably supported by a support wall of an engine; a variable valve device configured to advance or retard the camshaft by a hydraulic pressure; and an oil control valve. A thrust stopper is formed on an outer peripheral surface of the camshaft. A bearing surface of the support wall is formed with an advance groove through which oil for advancing the camshaft is to pass, a retard groove through which oil for retarding the camshaft is to pass, and an accommodation groove configured to accommodate the thrust stopper. At the bearing surface, the retard groove is positioned on one wall surface side of the support wall, the accommodation groove is positioned on the other wall surface side of the support wall, and the advance groove is positioned between the retard groove and the accommodation groove.

A hydraulic fluid control valve (HFCV) configured to recirculate an exiting hydraulic fluid from a first hydraulic actuation chamber to a second hydraulic actuation chamber is provided. The HFCV includes a selectively movable spool having an inner fluid chamber configured to receive and deliver the exiting hydraulic fluid to one or both of either a sump or one of the first or second hydraulic actuation chambers.

A fluid control valve includes: a sleeve in a bottomed cylindrical shape, including an inlet, communication ports, an inner peripheral surface, and an inflow annular groove recessed from the inner peripheral surface in a region facing the inlet; a spool slidably disposed on the inner peripheral surface in the sleeve to open and close the communication ports; a C-shaped leaf spring formed by bending a leaf spring into an annular shape with two ends facing each other to form a notch and disposed in the inflow annular groove capable of being contracted in diameter to open and close the inlet; and a restricting part provided on the sleeve for restricting diameter contraction of the C-shaped leaf spring beyond a predetermined inner diameter and for restricting a position of the notch in a region away from the inlet.

A camshaft phaser is provided that includes a rotor, a stator, and a locking cover. The rotor is selectively locked to the stator via a locking assembly arranged within a locking bore of the rotor. Contaminant particles that enter a first locking end of the bore are exited out a second venting end of the bore via a contaminant particle exit pathway.

A fluid control valve unit includes: a fluid control valve including a sleeve that defines an axis and a spool slidably disposed in the sleeve; a passage member including an inner peripheral surface to which the sleeve is fitted, passages, an annular receiving part facing one end of the sleeve, an opening adjacent to the annular receiving part, and an annular groove formed adjacent to the other end of the sleeve and recessed from the inner peripheral surface; a filter member including an elastic part sandwiched between the one end of the sleeve and the annular receiving part and exerting a biasing force in the axial direction; and a snap ring fitted in the annular groove for receiving the other end of the sleeve and detachably receiving the spool.

A hydraulic fluid control valve (HFCV) configured to recirculate an exiting hydraulic fluid from a first hydraulic actuation chamber to a second hydraulic actuation chamber is provided. The HFCV includes a selectively movable spool having an outer annulus configured to receive and deliver the exiting hydraulic fluid to one or both of either a sump or one of the first or second hydraulic actuation chambers.

An oil passage portion forms a part of an oil supply passage inside. A check valve part includes a valve seat portion press-fitted into the oil passage portion. The check valve part allows flow of hydraulic oil from a hydraulic oil supply source to a hydraulic chamber, and restricts flow of the hydraulic oil from the hydraulic chamber to the hydraulic oil supply source. A filter is provided downstream of the valve seat portion in the oil supply passage so as to collect a foreign matter in the oil supply passage.

An engine includes at least one cylinder, a first intake valve and a second intake valve associated with the cylinder, to control a flow of intake air from a first intake duct and a second intake duct, respectively. The two intake ducts communicate with a common intake manifold, so as to receive air at the same pressure. During the intake stage, in each cylinder operating cycle, initially an opening and closing movement of only the first intake valve is activated, while the second intake valve remains closed and, subsequently, an opening and closing movement of only said second intake valve is activated, while the first intake valve remains closed. In this way, the two air flows at the same pressure entering the cylinder give rise to a high turbulent kinetic energy, to the advantage of combustion efficiency and reduction of harmful exhaust emissions.

An annular groove has: a side peripheral surface that is shaped in a ring form and is formed such that the side peripheral surface inwardly extends from a bottom surface of the annular groove in a radial direction of a tubular member and is joined to an inner peripheral wall of the tubular member; and a specific shape surface that is formed along at least a part of the side peripheral surface between a bottom surface side end part and an inner peripheral wall side end part of the side peripheral surface such that a diameter of the specific shape surface is progressively reduced in an axial direction of the tubular member from one axial side, at which the bottom surface is placed, toward another axial side, at which the inner peripheral wall is placed.

In a first state: a spool valve of a control valve is disposed such that a second spool oil passage is closer to a second side in a longitudinal direction than a first spool oil passage; and as the spool valve has traveled toward the second side against a biasing force of a biasing member, a first port communicates with a second port via the first spool oil passage, a first sleeve oil passage, and the second spool oil passage. In a second state: the spool valve is disposed such that the first spool oil passage is closer to the second side than the second spool oil passage; and as the spool valve has traveled toward a first side in the longitudinal direction, the first port communicates with the second port via the first spool oil passage, the first sleeve oil passage, and the second spool oil passage.