A check valve part includes: a valve seat hole into which hydraulic oil flows; a valve seat formed around the valve seat hole; a lateral hole formed to have an axis intersecting an axis of the valve seat hole; and a valve body provided so as to be separated from the valve seat or abutted against the valve seat. The valve timing adjustment device further includes a back pressure oil passage that communicates a space opposite to the valve seat with respect to the valve body with the lateral hole.

A valve timing adjustment device includes a driving-side rotatable body and a driven-side rotatable body. The driving-side rotatable body is configured to be rotated about a rotational axis synchronously with a drive shaft and includes a sprocket portion and a housing portion. The sprocket portion is configured to receive a drive force transmitted from the drive shaft. The housing portion is shaped in a tubular form and is formed separately from the sprocket portion. The driven-side rotatable body is configured to be rotated about the rotational axis synchronously with a driven shaft.

Internal combustion piston engine includes a cylinder head partly defining two ducts and a combustion chamber, and poppet valves movably arranged in the cylinder head between positions allowing or preventing flow between the combustion chamber and the ducts. The poppet valve has a stem, a valve head having a hollow interior space, a lower surface facing the combustion chamber, an upper surface including a portion adjacent the stem, and a peripheral edge section that extends from the upper surface of the valve head to the lower surface. The valve head is formed separate from but connected to the valve stem in a manner to enclose the hollow space, for example, by a circumferential welding seam. The peripheral edge section contains an arcuate contact surface that extends from the upper to lower surfaces of the valve head and without any sharp edges between upper and lower surfaces.

A poppet valve, in particular a hollow poppet valve, includes: a valve stem; a valve body having along a longitudinal axis, a first end with a neck portion to which the valve stem is coaxially arranged and having along a longitudinal axis a second end with a first conical contact face portion, the valve body including a cavity with a first opening towards the first end and a second opening towards the second end; and a valve cap coaxially arranged to the valve body on the second end for closing the second opening, the valve cap having a second conical contact face portion to form together with the first conical contact face portion a valve head contact face.

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.

An actuator for a hydraulic valve for a cam phaser, the actuator comprising a magnetisable actuator housing that envelops a magnet coil; a pole group that is arranged in a housing receiver opening of the magnetisable actuator housing, wherein the pole group includes a pole core and a pole tube, wherein the pole core and the pole tube are connected by a connection bar and the pole core is connected with the connection bar by a pole core cone, or the pole tube is connected with the connection bar by a pole tube cone, wherein an armature is received axially movable in an inner space of the pole group.

A cylinder head cover for covering a cylinder head of an internal combustion engine having at least one first sealing surface via which the cylinder head cover can be tightly connected to an associated second sealing surface on the cylinder head, the cylinder head cover may include at least one first reference surface configured for unambiguous position-fixing on an associated second reference surface of the cylinder head. The at least one first reference surface and the at least one first sealing surface may be formed separately from one another.

This strain wave gear unit includes: a bottomed cylindrical first internal gear having internal teeth formed on a cylindrical part and a teeth-non-formed part protruding farther inward than the tooth bottom of the internal teeth in a corner area where a bottom wall part is integrally connected to the cylindrical part; a flexible cylindrical external gear having external teeth meshing with the internal teeth of the first internal gear, an opposed part opposed to the teeth-non-formed part with a gap therebetween, and an end part opposed to the bottom wall part to make contact therewith; a second internal gear arranged adjacent to the first internal gear and having internal teeth meshing with the external teeth; and a rotation member that causes the external gear to deform in an oval shape and causes the meshing position to move while partially meshing with the first internal gear and the second internal gear.

A sealing device seals a rod having a cylindrical part and a cylindrical guide that guides reciprocation of the rod in an axial direction of the rod. The sealing device includes an elastic ring formed of an elastic material, and a rigid ring formed of a rigid material fixed to the elastic ring for reinforcing the elastic ring. The elastic ring includes a lip with which an outer peripheral surface of the rod is in slidable contact. The rigid ring includes a rigid-ring cylindrical part located radially outside an end portion of the guide. The rigid-ring cylindrical part includes multiple hook hasps engaged into at least one recess formed on an outer peripheral surface of the guide. Each of the multiple hook hasps includes a root portion and a distal end portion located radially inward of the root portion and fitted into the recess. A thin portion is formed at the root portion of the hook hasp, the thin portion being thinner than other parts of the hook hasp.

A method of manufacturing an engine valve intermediate product with a boss portion formed in integral fashion at an outer circumferential surface at an intermediate location on a stem forming portion. The manufacturing method may comprise a stem retaining operation in which an intermediate location of the stem forming portion is retained by a plurality of intermediate jigs removably installable radially with respect to a center of the stem forming portion, and a base end portion is retained by a base end jig. The manufacturing method may further comprise a stem enlarging operation in which compressive forces are applied from both ends of the intermediate product and the boss portion is formed as the intermediate product is made to rotate and alternating loads that cause tensile forces and compressive forces to act in repeated and alternating fashion at the outer circumferential surface of the stem forming portion are applied.