An exhaust valve system for a two-stroke internal combustion engine having: at least one exhaust valve movable between open and closed positions; an actuator for moving the at least one exhaust valve; a valve position sensor; a controller communicating with the actuator and the valve position sensor. The controller being programmed for: controlling the actuator to attempt to move the at least one exhaust valve to a desired one of the open and closed positions; determining if the at least one exhaust valve has failed to reach the desired position based on the position of the at least one exhaust valve sensed by the valve position sensor; and controlling the actuator to move the at least one exhaust valve to an intermediate position when the at least one exhaust valve has failed to reach the desired position.

A hydraulic oil control valve includes an outer sleeve, an inner sleeve and a spool. The outer sleeve includes: a threaded portion, which is fixed to a camshaft; a projection, which is fixed to a phase changer; and ports, which are formed at a peripheral surface of the outer sleeve between the threaded portion and the projection. The inner sleeve includes: ports, which are communicated with the ports of the outer sleeve; an oil port; an axial groove; and an enlarged diameter portion, which is located on one side of the projection where an insertion opening of the outer sleeve is placed. The spool includes: land portions, which are configured to slide along an inner peripheral surface of the inner sleeve and are located at an outer periphery of the spool at a location that is on another side of the projection where the threaded portion is placed.

Provided is a valve seat insert for an internal combustion engine, which has both an excellent heat dissipation property and excellent wear resistance. The valve seat insert for an internal combustion engine is used while being press-fitted into an aluminum alloy cylinder head, is made of an iron-based sintered alloy, is formed by integrating two layers of a functional member side layer and a supporting member side layer, and has a plating film on at least an outer peripheral side. The plating film is preferably a copper plating film. The plating film is a plating film having a thickness of 1 to 100 μm and a hardness of 50 to 300 HV, and the hardness of the plating film is adjusted so as to satisfy a range of 1.05 to 4.5 times hardness of the cylinder head in Vickers hardness HV. Pores contained in the valve seat insert are preferably sealed with a curable resin before plating treatment. Consequently, a valve seat insert for an internal combustion engine which does not go through complicated processes, is not accompanied by a significant decrease in wear resistance compared with the prior art, and has an excellent heat dissipation property is provided. If a roughened surface region is further formed at at least one portion on the outer peripheral surface of the valve seat insert in addition to the plating film, a falling out resistance property is improved. The same effect can be obtained even if the valve seat insert is a single layer of only the functional member side layer.

A control valve (1) for a camshaft adjustment device, and to an internal combustion engine having a camshaft adjustment device and a control valve (1) is provided. The control valve (1) includes a valve housing (3) and a pressure medium guiding insert (23) arranged coaxially in a recess of the valve housing (3). A discharge passage (27, 28) of the pressure medium guiding insert (23) transitions into a discharge duct (22) running in the axial direction, wherein the discharge connection T can be connected to the control connection A, B and wherein the discharge connection T is arranged in a region between the second end (8), which is opposite the first end (6), and the control connections A, B.

A copper alloy for valve seats, and more particularly a copper alloy for valve seats with improved wear resistance, contains 12 to 24% by weight of Ni, 2 to 4% by weight of Si, 7 to 13% by weight of Cr, 20 to 35% by weight of Fe, and a balance of Cu and other impurities.

The invention relates to an electromagnetic actuating device (20) having at least two actuator units (1a, 1b) which are arranged adjacently in a housing (10) and which each have electrically energizable static coil means (2a, 2b), armature means (3a, 3b) mounted so as to be movable relative to said coil means, and a plunger (4a, 4b) which interacts with the armature means (3a, 3b) and which is mounted so as to be movable along axial plunger direction (S1, S2) and which has a free end portion (5a, 5b) for engagement into an actuation partner, in particular a guide groove of a camshaft, wherein the plungers (4a, 4b) of the actuator units (1a, 1b) of the actuating device (20) are preferably arranged such that the plunger directions (S1, S2) thereof run parallel to one another, and wherein the device (20) has adjustment means (6) which are integrated in the housing (10) and which serve for varying the arrangement of at least one plunger along a plane (E) perpendicular to the respective plunger direction (S1, S2).

A hydraulic oil control valve includes a sleeve, a spool and a spring. The spool is received at an inside of the sleeve and is configured to be reciprocated. The spring is configured to be seated against a spring seat of the sleeve and is configured to apply a preload to the spool. The sleeve has a stepped portion, which has a spool contact surface for limiting movement of the spool toward the spring seat, and a protrusion, which is located at a center of the spring seat and protrudes toward an opening of the sleeve. The protrusion has a sloped peripheral surface. The protrusion is configured such that in a state where an end portion of the spring is not seated against the spring seat while the spring is placed adjacent to the spring seat, the end portion of the spring contacts the protrusion.

Aspects of the present invention relate to a valve seat (20) for a poppet valve of an internal combustion engine, wherein the poppet valve comprises a head and a stem behind the head, the valve seat comprising: an aperture (21) configured to form a seal with the head of the poppet valve when the poppet valve is in a closed position; and a peripheral body (22) defining, at least in part, one or more ports (23) shaped like e.g. grooves and sized to enable injection of liquid or gas from a cylinder head of the internal combustion engine into a gas stream behind the head of the poppet valve.

An oil passage switching valve suitable for a valve timing changing apparatus includes: a valve body, opening or closing an oil passage of operating oil; an urging spring, urging to position the valve body to a position corresponding to the retard position in a pause state; and a switching element, positioning the valve body to a position corresponding to the retard position when a state quantity of the operating oil is in a first range, and switching a position of the valve body in response to the state quantity (pressure or temperature) of the operating oil while resisting an urging force of the urging spring to position the valve body to a position corresponding to the advance position when the state quantity of the operating oil is in a second range greater than the first range.

A valve timing adjustment device includes a hydraulic oil control valve. The hydraulic oil control valve includes: an outer sleeve that is shaped in a tubular form and has a projection at an outer periphery of the outer sleeve; an inner sleeve that is located on an inner side of the outer sleeve; and a spool that is located at an inside of the inner sleeve. A reference-shape portion, which serves as a reference at a time of positioning the outer sleeve relative to the inner sleeve, is formed at an outer periphery of the projection. A seat surface of the projection, which fixes a vane rotor between the seat surface of the projection and an end portion of one of a drive shaft and a driven shaft, is shaped in a rotationally symmetric form that is rotationally symmetric around a rotational axis.