An assembling apparatus places a retainer on a valve spring to surround an upper end of a valve stem. The apparatus includes an assembling head, and a moving unit configured to move the assembling head between the supply position of the retainer and an assembling position. The assembling head includes a holding unit configured to hold the retainer, and a push unit configured to push out the retainer. The push unit includes a push member supported to be able to advance/retreat along an elevating direction of the assembling head, and a biasing member configured to bias the push member in an advancing direction.

According to one aspect of the present invention, a sliding member includes: a sliding surface against which an outer surface of a cam abuts; and a groove having a spiral shape or a plurality of grooves having an annular shape, which are provided on the sliding surface.

The sliding surface includes a central region having a circular shape and including a center of the sliding surface, and a first annular region located outside the central region. A ratio R.sub.C of a width L2 of the groove to a pitch L1 of the groove in the central region is larger than a ratio R.sub.O1 of the width L2 of the groove to the pitch L1 of the groove in the first annular region.

A cover body (2) for a valve rotating device includes a ring-shaped upper part (4) and a ring-shaped lower part (6). The upper part (4) and the lower part (6) are axially spaced apart and are adapted to accommodate an axial spring element (24) therebetween. The upper part (4) and the lower part (6) are connected to one another by at least one connecting piece arranged at the location opposite an insertion position of the axial spring element (24).

A valve rotating device (12) having such a cover body is also provided. A ring-shaped base body (22) hasg a plurality of pockets (16) oriented in a circumferential direction, in each of which a ball (14) and a tangential spring (32) are arranged. The pockets (16) have a variable depth in the circumferential direction such that inclined raceways (26) for the balls (14) arranged therein are formed. The tangential springs (32) push the balls (14) toward an end of the respective pocket (16). The axial spring element (24) is ring-shaped and a first end of the axial spring element (24) is supported on an ring-shaped stop surface (18) of the base body (22) and a second end of the axial spring element (24) is supported on a surface of the upper part (4) of the cover. A surface of the lower part (6) facing away from the axial spring element (24) rests against the balls (14), and wherein the balls (14) and the axial spring element (24) are arranged overlapping in the radial direction.

A method for producing a cover body (2) for a valve rotating device is also provided.

A method and apparatus for automated valve spring assembly includes a head assembly with a pair of elongated passageways that moveably support a pair of retainer keys for movement through the passageways. The head assembly including a moveable divider plate and a pair of jaws, a push member that closes off the passageways and that slides the retainer keys along opposite sides of the divider plate. The retainer keys contact surfaces of the jaws and rotate the jaws outwardly as the keys are moved by the pushrod. The retainer plate is then retracted, and the jaws shift inwardly and push or position the retainer keys on the valve stem where the retainer plate is configured to allow sequential engagement of the rings of the retainer keys to engage the valve stem.

A method and apparatus for automated valve spring assembly includes a head assembly with a pair of elongated passageways that moveably support a pair of retainer keys for movement through the passageways. The head assembly including a moveable divider plate and a pair of jaws, a push member that closes off the passageways and that slides the retainer keys along opposite sides of the divider plate. The retainer keys contact surfaces of the jaws and rotate the jaws outwardly as the keys are moved by the pushrod. The retainer plate is then retracted, and the jaws shift inwardly and push or position the retainer keys on the valve stem where the retainer plate is configured to allow sequential engagement of the rings of the retainer keys to engage the valve stem.

An internal combustion engine switches valve operation states, reduces or prevents wear of a cam and a rocker arm, and reduces the size of the cylinder head to ensure a sufficient valve lift amount. A valve spring retainer includes a cylindrical portion including a first through hole with an inner diameter decreases from the first end portion toward the second end portion, a cone-shaped portion including a second through hole with an inner diameter increases as it extends away from the second end portion of the cylindrical portion, and a flange portion extending radially outward from the cone-shaped portion. An outer diameter of the cylindrical portion is constant from the first end portion to the second end portion, and an outer diameter of the cone-shaped portion increases as it extends away from the second end portion.

An internal combustion engine switches valve operation states, reduces or prevents wear of a cam and a rocker arm, and reduces the size of the cylinder head to ensure a sufficient valve lift amount. A valve spring retainer includes a cylindrical portion including a first through hole with an inner diameter decreases from the first end portion toward the second end portion, a cone-shaped portion including a second through hole with an inner diameter increases as it extends away from the second end portion of the cylindrical portion, and a flange portion extending radially outward from the cone-shaped portion. An outer diameter of the cylindrical portion is constant from the first end portion to the second end portion, and an outer diameter of the cone-shaped portion increases as it extends away from the second end portion.

A method for manufacturing an engine poppet valve may comprise a forging operation, a diameter-decreasing operation, and a joining operation. At the forging operation, an intermediate member at which a valve head portion and an intermediate stem portion are made integral by way of a neck portion may be formed. At the diameter-decreasing operation, the intermediate stem portion may be inserted between/among a plurality of diameter-decreasing tools that have stem member compressing surfaces and stem member inlet surfaces formed so as to be progressively distant from the stem member compressing surfaces and toward the tip end and that are arranged at a plurality of circumferentially equipartite locations about a circumference of the intermediate stem portion, application at the intermediate stem portion from a base end portion of compressive forces which are inwardly directed in a radial direction from the compressing surfaces of the respective diameter-decreasing tools which have been made to come in contact with a part of the intermediate stem portion that has been made to rotate while being displaced in relative fashion in a direction along a central axis thereof causing the part of the intermediate stem portion to be decreased in diameter from the base end portion and causing a main body portion of a first stem portion to be formed at the intermediate member and also causing formation by the compressing surfaces of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter of a remaining portion at the intermediate stem portion, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion. At the joining operation, a stem end member having a same outside diameter as the main body portion may be joined to a base end portion of the main body portion.

An assembly method is provided by orienting a cylinder-head at a first orientation. A first plurality of spring caps and a first plurality of retainer keys are installed into the cylinder-head in the first orientation by a first robot. A first plurality of valves is installed into the cylinder-head in the first orientation by a second robot, into engagement with the first plurality of retainer keys. An end effector is provided with an actuator supported upon an adapter plate. A shaft extends from the actuator with a mating surface to engage a spring cap. Porting is provided through the shaft to convey pressurized air upon a plurality of retainer keys within the spring cap. A plurality of gripper fingers extend from the distal end of the shaft to grip a valve spring while retaining a spring cap between the valve spring and the mating surface of the shaft.

An assembly method is provided by orienting a cylinder-head at a first orientation. A first plurality of spring caps and a first plurality of retainer keys are installed into the cylinder-head in the first orientation by a first robot. A first plurality of valves is installed into the cylinder-head in the first orientation by a second robot, into engagement with the first plurality of retainer keys. An end effector is provided with an actuator supported upon an adapter plate. A shaft extends from the actuator with a mating surface to engage a spring cap. Porting is provided through the shaft to convey pressurized air upon a plurality of retainer keys within the spring cap. A plurality of gripper fingers extend from the distal end of the shaft to grip a valve spring while retaining a spring cap between the valve spring and the mating surface of the shaft.