Nippon Piston Ring Co., Ltd.

Tetsuo Masuyama

Yoshikatsu Nakamura

Takao Omiya

Yasuo Suzuki

Hiroshi Takiguchi

Nobuyuki Matsushima

Kunihiro Iguchi

The present invention provides a piston ring comprising a piston ring main body and an expander ring arranged on an inner peripheral surface thereof, the expander ring comprising two oil expander rings, one of which is housed in a space in a spiral of the other. The expander ring is formed so that the pressing force in the diameter expanding direction is larger in a high temperature state than in a low temperature state. The expander comprises two different kinds of expander members. One of these expander members has the same functions as those of a conventional expander, and the other is a member in which there occurs a change in tension in the diametral direction with temperature. As a result, the pressing force of the master expander member having the same effects as those of the conventional expander is made variable.

Piston ring

The present invention provides a synchronizer ring excellent in strength and abrasion resisting property, used in a speed change gear. This synchronizer ring according to the invention is consisted of, by weight, C:0.2&tilde;1.0%, Ni:1.0&tilde;6.0%, Mo:0.6&tilde;3.0%, Cu:1.0&tilde;4.0% and the reminder Fe and inevitable impurities, and is made of Fe sintered alloy of which base composition comprises of mainly martonsite and bainite. And the base composition is preferably consisted of, by volume, martensite: 57&tilde;80%, bainite: 17&tilde;40%, austenite: 8% or less.

Synchronizer ring

In an aspect of the present invention, a synchronizer ring, made of Fe-based sintered alloy, having an internal circumferential surface 101, is provided, the internal circumferential surface 101 being adapted to detachably engage in synchronized sliding with a rotating counterpart member thereof. At least the internal circumferential surface 101 is applied with aqueous vapor treatment to form iron oxide film thereon. In another aspect of the present invention, the iron oxide film has surface roughness not less than 20 .mu.mRz but not more than 55 .mu.mRz. In a further aspect of the present invention, the iron oxide film has a surface roughness not less than 25 .mu.mRz but not more than 35 .mu.mRz. In another aspect of the present invention, the iron oxide film has a thickness not less than 0.05 .mu.m but not more than 5 .mu.m. In a further aspect of the present invention, the major component of the iron oxide film is Fe.sub.3 O.sub.4. In a still further aspect of the present invention, at least the internal circumferential surface is applied with blasting treatment in addition to, and in combination with, the aqueous vapor treatment to form iron oxide film thereon.

A synchronizer ring performing synchronous sliding operation with and separating operation from a rotating object member, is composed of an Fe sintered alloy. The Fe sintered alloy comprises carbon of from 1.2 wt. % to 2.0 wt. %, copper of from over 15.0 wt. % to 25.0 wt. %, and the balance being iron and incidental impurities. A free Cu phase is precipitated in a matrix of the synchronizer ring. The synchronizer ring has a high scuffing resistance, an excellent friction characteristic, and sufficient abrasion resisting property and strength, and moreover, provides an easy manufacture thereof by means of a size working and is stable in quality.

An inline type check valve having a tubular body, a mushroom or umbrella-shaped piston axially, movably mounted in the tubular body, a coil spring disposed behind the piston in the body, and a hollow disk axially removably fixed to the body. Both the body and the disk made from a synthetic resin reinforced with fibers and resiliently hooked in each other. The piston has its periphery provided with a plurality of grooves to increase the cross-sectional area for fluid flow through the valve.

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Saitama, Japan

Tetsuo Masuyama