Valve timing regulator

Abstract

A valve timing adjusting apparatus includes: recesses provided opposite to the wall surfaces in a circumferential direction of a shoe and a vane in an advance hydraulic chamber; a holding member insertion-disposed into the recesses from an axial direction; and an assist spring disposed between the holding member on the shoe side and the holding member on the vane side to urge a rotor in an advance direction, and further a clearance formed by a length in the axial direction of the holding member provided on the vane side and a length in the axial direction of the case is set to not less than a sum of an increment of the length in the axial direction in consideration of a tilt of the holding member produced by a gap between the holding member and recess, and an increment due to the thermal expansion.

Description

TECHNICAL FIELD[0001]The present invention relates to a valve timing adjusting apparatus that changes automatically opening and closing timings of an exhaust valve in response to an operating condition of an internal combustion engine.BACKGROUND ART[0002]This type of valve timing adjusting apparatus includes: a camshaft for driving an exhaust valve of an internal combustion engine to open and close; a case that is rotatably provided on the camshaft and rotationally driven by an output of the internal combustion engine; a rotor that is relatively rotatably housed inside the case and coupled to the camshaft; and a locking means that constrains a relative rotation between the case and the rotor when operated by a mechanical urging force, and releases the constraint when operated by a fluid control pressure applied from an internal hydraulic chamber in a direction opposing the mechanical urging force.[0003]With the aim of applying the thus constructed valve timing adjusting apparatus to...

AI Technical Summary

Benefits of technology

[0007]A valve timing adjusting apparatus according to the present invention includes: a plurality of shoes formed on an inner peripheral surface of a case; a plurality of vanes provided on an outer peripheral surface of a rotor relatively rotatably housed in the case, each forming a retard hydraulic chamber and an advance hydraulic chamber between the vane and the two side-wall surfaces in a circumferential direction of the corresponding shoe; recesses provided opposite to the wall surfaces in the circumferential direction of the shoe and the vane in the advance hydraulic chamber; a holding member insertion-disposed into the recess from an axial direction; and an assist spring disposed between the holding member on the shoe side and the holding member on the vane side to urge the rotor in an advance direction, wherein a clearance formed by a length in the axial direction of the holding member provided on the vane side and a length in the axial direction of the case is set to be equal to or greater than a sum of an increment of the length in the axial direction in consideration of a tilt of the holding member produced by a gap between the holding member and the recess, and an increment due to the thermal expansion.

Problems solved by technology

Therefore, in a practical use, the holding member may tilt within the range of a gap between the holding member and the recess or is fallen in a stretched state between a cover and a housing at the two ends thereof due to the thermal expansion or the like; thus, there is a problem such that inconveniences such as a reduction in a rotor operating speed due to the friction and an increase in leakage due to the wear on the sliding surface between the cover and the housing are concerned.

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