Abstract: An automobile exhaust-pipe joint structure and a coil spring for use therein. The exhaust pipe connection structure includes a first exhaust pipe having a first flange section, a second exhaust pipe having a second flange section, a ball joint section for connecting the first and second exhaust pipes flexibly, and coupling mechanisms provided at a plurality of positions of the first and second flange sections. One exemplary coupling mechanism includes a bolt member penetrating the first flange section and being secured, at one end part thereof, to the second flange section, and a coil spring of deformed cross-section interposed between the other end part of the bolt member and the first flange section, wherein the cross-section of a wire is reduced in diameter, in the compressing direction with a dimensional ratio between the short diameter and long diameter thereof being in the range of 1.1–2.6.

Abstract: A coil spring according to the present invention is used as a coil spring in an automobile exhaust-pipe joint structure. The automobile exhaust-pipe joint structure of the invention is a coil spring using the coil spring according to the invention.

Abstract: A catalyst container of a catalytic converter is of a double-pipe structure wherein an outer periphery of an inner pipe and an inner periphery of an outer pipe are fittingly superposed on each other. The catalyst container has a catalyst installing portion, tapered cone portions extending from the catalyst installing portion with a gradually decreasing diameter, and straight connecting portions extending from smallest-diameter regions of the cone portions to the ends to be connected with connecting pipes upstream and downstream of the catalytic converter. Holes maybe formed in the cone portions of one of the inner or outer pipes to permit fluids to be displaced from the space therebetween. Such a catalyst container has sufficient rigidity and radiated noise suppression properties and thus can be reduced in weight by being thinned.

Abstract: A catalyst container of a catalytic converter is of a double-pipe structure wherein an outer periphery of an inner pipe and an inner periphery of an outer pipe are fittingly superposed on each other. The catalyst container has a catalyst installing portion, tapered cone portions extending from the catalyst installing portion with a gradually decreasing diameter, and straight connecting portions extending from smallest-diameter regions of the cone portions to the ends to be connected with connecting pipes upstream and downstream of the catalytic converter. Holes maybe formed in the cone portions of one of the inner or outer pipes to permit fluids to be displaced from the space therebetween. Such a catalyst container has sufficient rigidity and radiated noise suppression properties and thus can be reduced in weight by being thinned.

Abstract: A spiral wound gasket having an annular body serving as a centering member which is integrally disposed at the inner periphery side of a gasket body formed by winding, in the form of a spiral. The gasket body comprises a metal hoop material and a filler material overlapping each other. When this gasket is disposed at fit-joint-type pipe connection portions of the exhaust pipe system in a motor vehicle, the annular body serves as a centering member to prevent the gasket body from protruding into the fit joint. This prevents the gasket body from deterioration and damage, thus assuring a high sealing property for a long period of time. Further, merely by inserting and fitting the gasket, the gasket may be automatically aligned and positioned with respect to the fit joint. Further, the inner peripheral surface of the gasket body and the annular body form an annular closed space, thus making the entire gasket into a lightweight design.