Ntn Corporation

Hiroo Morimoto

Kazuhiko Yoshida

Yukio Matsubara

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.

Hydraulic auto-tensioner

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.

Hydraulic auto tensioner

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.

Outer member of constant speed universal joint

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.

Growing community of inventors

Shizuoka, Japan

Hiroo Morimoto