This disclosure relates to a control valve for a hydraulic camshaft phaser. The control valve includes a screw body having a cavity, a plurality of connections opening into the cavity, and a sleeve-shaped hydraulic guide element firmly inserted radially inside the cavity. At least part of the hydraulic guide element consists of plastic. The hydraulic guide element includes a plurality of pressure medium channels which open into its radial interior, each of which is connected to at least one of the connections. A control piston is displaceably accommodated in the hydraulic guide element, and, depending on the position of the control piston, connects the connections to each other. A sealing contour provided on a radial outer side of the hydraulic guide element contacts the screw body, sealing the pressure medium channels with respect to each other and/or with respect to axial ends of the hydraulic guide element.

A method for producing a cam phaser for a cam shaft of an internal combustion engine, the cam phaser including a rotor, a stator and at least one cover, the method including arranging the at least one cover at the stator; and welding the at least one cover with the stator, wherein a first weld, a second weld and a third weld are formed at least on a large radius or on a small radius during the welding, and wherein the small radius is smaller than the large radius. The invention furthermore relates to a cam phaser for a cam shaft of an internal combustion engine, the cam phaser including a rotor; a stator and at least one cover.

Methods and systems are provided for providing secondary air to an exhaust system during catalyst warm-up. In one example, a method may include, during a cold start condition, operating an engine with a first number of cylinders unfired and a remaining number of cylinders fired during an engine cycle, opening an intake valve of an unfired cylinder of the first number of cylinders during an expansion stroke of the unfired cylinder, and opening an exhaust valve of the unfired cylinder during a compression stroke of the unfired cylinder. In this way, the unfired cylinders may provide the secondary air to the exhaust system during a stroke that increases mixing of the secondary air with burned exhaust gas from fired cylinders, thus increasing exotherm production in the exhaust system to increase a temperature of the catalyst.

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.

A camshaft adjuster is produced that includes a stator and a rotor, which is rotatable relative to the stator, wherein the stator and the rotor are produced with first planar surfaces on a first end face and with second planar surfaces on a second end face, which is formed to be opposite the first end face when viewed in an axial direction and wherein the rotor and/or the stator is or are produced according to a powder-metallurgical method, The first planar surfaces and the second planar surfaces of the stator and the rotor are ground or finished, and the lateral surface of the stator and the lateral surface of the rotor are left uncalibrated.

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.

Methods and systems are provided for providing secondary air to an exhaust system during catalyst warm-up. In one example, a method may include, during a cold start condition, operating an engine with a first number of cylinders unfired and a remaining number of cylinders fired during an engine cycle, opening an intake valve of an unfired cylinder of the first number of cylinders during an expansion stroke of the unfired cylinder, and opening an exhaust valve of the unfired cylinder during a compression stroke of the unfired cylinder. In this way, the unfired cylinders may provide the secondary air to the exhaust system during a stroke that increases mixing of the secondary air with burned exhaust gas from fired cylinders, thus increasing exotherm production in the exhaust system to increase a temperature of the catalyst.

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.

A hydraulic oil control valve is coaxially disposed with a rotational axial of a valve timing adjustment device. The hydraulic oil control valve includes a sleeve, a spool slidably moving in an axial direction within the sleeve, and a filter member configured to capture foreign matters contained in the hydraulic oil. The sleeve includes an inner sleeve and an outer sleeve defining therein an axial hole extending in the axial direction. A space between the axial hole and the inner sleeve in a radial direction serves as a hydraulic oil supply passage. The filter member is disposed in the space to overlap with at least one of internal members in the inner sleeve when viewed in the radial direction.

A hydraulic oil control valve is coaxially disposed with a rotational axis of a valve timing adjustment device. The hydraulic oil control valve includes a sleeve and a spool sliding in an axial direction within the sleeve. The spool has an inner space serving as a drain passage through which the hydraulic oil discharged from a phase shifting portion flows. The spool defines a drain inlet that guides the hydraulic oil discharged from the phase shifting portion into the drain passage. At least one of the sleeve or the spool defines an opening through which the hydraulic oil in the drain passage is discharged from the hydraulic oil control valve. A protrusion is formed between the drain inlet and the opening to extend radially inward beyond the drain inlet.