Abstract: A hydraulic auto-tensioner includes a sleeve; a rod vertically movable relative to the sleeve; a spring seat fixed to the portion of the rod protruding beyond the sleeve; a return spring configured to bias the spring seat upwardly; oil passages through which a pressure chamber communicate with a reservoir chamber; a check valve mounted to the oil passages; a tubular plunger vertically movably mounted between the outer periphery of the rod and the inner periphery of the sleeve; a first leakage gap defined between the inner periphery of the tubular plunger and the outer periphery of the rod; an upper stopper configured to restrict the upwardly movable range of the tubular plunger; and a pressure regulating spring disposed above the tubular plunger so as to surround the outer periphery of the rod.

Abstract: A hydraulic auto-tensioner includes a cylinder, a valve sleeve, a rod, a spring seat, and a plunger slidably fitted on the outer diameter surface of the rod. A first leakage gap is defined between the fitting surfaces of the plunger and the rod. A second leakage gap is defined between the fitting surfaces of the plunger and the valve sleeve such that the resistance to oil flowing in the second leakage gap is larger than the resistance to oil flowing in the first leakage gap. With the engine running normally, when the tension of the belt increases, and thus a pushing force is applied to the hydraulic auto-tensioner such that the cylinder and the spring seat are pushed toward each other, oil in a pressure chamber leaks through the first leakage gap into a reservoir chamber.

Abstract: A hydraulic auto-tensioner includes a sleeve; a rod vertically movable relative to the sleeve; a spring seat fixed to the portion of the rod protruding beyond the sleeve; a return spring configured to bias the spring seat upwardly; oil passages through which a pressure chamber communicate with a reservoir chamber; a check valve mounted to the oil passages; a tubular plunger vertically movably mounted between the outer periphery of the rod and the inner periphery of the sleeve; a first leakage gap defined between the inner periphery of the tubular plunger and the outer periphery of the rod; an upper stopper configured to restrict the upwardly movable range of the tubular plunger; and a pressure regulating spring disposed above the tubular plunger so as to surround the outer periphery of the rod.

Abstract: A hydraulic auto-tensioner is provided which includes a cylinder, a valve sleeve, a rod, a spring seat, and a plunger slidably fitted on the outer diameter surface of the rod. A first leakage gap is defined between the fitting surfaces of the plunger and the rod. A second leakage gap is defined between the fitting surfaces of the plunger and the valve sleeve such that the resistance to oil flowing in the second leakage gap is larger than the resistance to oil flowing in the first leakage gap. With the engine running normally, when the tension of the belt increases, and thus a pushing force is applied to the hydraulic auto-tensioner such that the cylinder and the spring seat are pushed toward each other, oil in a pressure chamber leaks through the first leakage gap into a reservoir chamber.

Abstract: An outer member of a constant velocity universal joint suppresses occurrences of cracking in a joining portion and has stable quality. The outer member includes a cup section having track grooves formed therein, and a shaft section having one end coupled to a bottom portion of the cup section. By joining members having different carbon contents and performing induction hardening on the members, a hardening heat-affected portion affected by the induction hardening, a hardening heat-unaffected portion unaffected by the induction hardening, a joining heat-affected portion affected by heat generated during the joining, and a joining heat-unaffected portion unaffected by the heat generated during the joining are formed. A martensitic structure is eliminated from the hardening heat-unaffected portion of the high carbon content member and is the joining heat-affected portion at an end portion including a joining end surface that is to be joined to the low carbon content member.

Abstract: A power transmission shaft mitigates the concentration of both tensile stress and shear stress to achieve an improvement in terms of fatigue strength. A male spline section is formed on an outer periphery of the power transmission shaft. On a valley section of the male spline section, at an axially opposite end side portion thereof, there is provided a diameter-expanded section whose outer diameter dimension is gradually increased toward an axially opposite end. Rounded sections having a circular arc cross-section are provided on both circumferential sides of the diameter-expanded section. A radius of curvature of the rounded sections is gradually increased toward the axially opposite end.

Abstract: Provided is an outer member of a constant velocity universal joint, which suppresses occurrence of cracking in a joining portion of the constant velocity universal joint and has stable quality. The outer member of the constant velocity universal joint includes: a cup section (1) having a plurality of track grooves formed therein; and a shaft section (2) having one end coupled to a bottom portion of the cup section (1). By joining members having different carbon contents to each other and then performing induction hardening on the members, a hardening heat-affected portion affected by the induction hardening, a hardening heat-unaffected portion unaffected by the induction hardening, a joining heat-affected portion affected by heat generated at a time of the joining, and a joining heat-unaffected portion unaffected by the heat generated at the time of the joining are formed.

Abstract: Provided is a power transmission shaft in which concentration of both tensile stress and shear stress is mitigated to achieve an improvement in terms of fatigue strength of a power transmission shaft. A male spline section (Sm) is formed on an outer periphery of the power transmission shaft. On a valley section (21) of the male spline section (Sm), at an axially opposite end side portion thereof, there is provided a diameter-expanded section (21b) whose outer diameter dimension is gradually increased toward an axially opposite end. Rounded sections (21b1) having a circular arc cross-section are provided on both circumferential sides of the diameter-expanded section (21b). A radius of curvature of the rounded sections (21b1) is gradually increased toward the axially opposite end.

Abstract: The present invention provides a power transmission shaft that is capable of eliminating the usual tempering step thereby reducing the production cost, is capable of realizing an inline production process of the shaft, and has higher strength. The invention also provides a method for producing the power transmission shaft. The power transmission shaft is composed of a carbon steel having a carbon content of from 0.30 to 0.48 wt % and of a surface hardened layer 4 formed by high frequency quenching. The surface hardened layer 4 has a tempering-effected portion subjected to tempering using heat generated by external force applied after quenching. The residual stress of the portion subjected to tempering by applying external force is equal to or less than ?800 MPa.