A hydraulically-actuated variable camshaft timing (VCT) system comprises a spool valve including a sleeve and a spool, having a plurality of radially-outwardly extending lands, received within a sleeve; a sleeve fluid pathway, extending axially along the sleeve and formed within the sleeve, configured to receive fluid from a fluid supply; an advancing port in the sleeve in fluid communication with an advancing chamber of a hydraulically-actuated camshaft phaser; a retarding port in the sleeve in fluid communication with a retarding chamber of the hydraulically-actuated camshaft phaser; a first fluid supply port formed in the sleeve; a second fluid supply port formed in the sleeve; and an exhaust port axially positioned in the sleeve in between the first fluid supply port and the second fluid supply port or in between the advancing port and the retarding port, wherein the exhaust port is configured to selectively receive fluid from either the advancing chamber or the retarding chamber depending on an axial position of the spool relative to the sleeve.

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.

The valve timing control unit includes a valve timing control mechanism that includes a driving rotary body, a driven rotary body, an electric motor and a deceleration gear each for setting the relative rotational phase of the driving rotary body and the driven rotary body, and a phase sensor unit that detects the actual phase of the driving rotary body and the driven rotary body. The valve timing control unit includes a controller that controls the electric motor to reduce a phase difference between the actual phase and a target phase, and the controller includes a swing controller that swings the target phase in vicinity of the target phase when the target phase is maintained and the actual phase having a fluctuation amount is held in a holding region, in which the fluctuation amount is less than a preset value.

A valve opening and closing timing control device includes a driving-side rotating body, a driven-side rotating body, a stopper configured to determine a mechanical limit of a displacement region of a relative rotation phase, a phase control mechanism configured to change the relative rotation phase, and a control unit configured to control the electric motor so as to displace the actual phase detected by a phase sensor. A limit phase at which the stopper reaches an abutting state is set in advance when rotation of the electric motor is stopped while the internal combustion engine operates. Upon executing stop control of stopping the internal combustion engine, except when the actual phase is already the limit phase, the control unit executes braking control of limiting the rotation of the electric motor by controlling an electric current to be supplied to the electric motor.

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.