Spiral wound gasket

Abstract: In the spiral wound gasket (1) according to the present invention, an annular body (5) serving as a centering member is integrally disposed at the inner periphery side of the gasket body (4) formed by winding, in the form of a spiral, a metal hoop material (2) and a filler material (3) as overlapping each other. For example, when this gasket (1) is disposed at fit-joint-type pipe connection portions of the exhaust pipe system in a motor vehicle, the annular body (5) serves as a centering member to prevent the gasket body (4) from protruding into the fit joint. This prevents the gasket body (4) from being deteriorated and damaged, thus assuring high sealing properties for a long period of time. Further, merely by inserting and fitting the gasket (1), the gasket (1) may be automatically aligned and positioned with respect to the fit joint. Further, the inner peripheral surface of the gasket body (4) and the annular body (5) form an annular closed space, thus making the entire gasket in a lightweight design.

Description: Background of the Invention 1. Field of the Invention The present invention relates to a gasket excellent in sealing properties to be disposed at fit-joint-type pipe connection portions of, for example, the exhaust pipe system in a motor vehicle in which a high-temperature gas flows. More specifically, the present invention relates to a spiral wound gasket formed by winding, in the form of a spiral, a metal hoop material and a filler material as overlapping each other. 2. Description of the Invention As a gasket to be used for sealing the ends of exhaust pipes in, for example, an internal combustion engine, there is known a gasket as disclosed in Japanese Utility Model Publication 190665/1988. Such a gasket is made in the following manner. As shown in Figs. 8 and 9, a gasket 22 is formed by winding, in the form of a ring, a band-like steel sheet 20 and a gasket material 21 such as asbestos as overlapping each other. In the gasket 22, the winding end 20A of the band-like steel sheet 20 at the outer periphery side of the gasket 22 is raised such that, when the gasket 22 is inserted into a large-diameter portion 24 of an exhaust hole 23, the winding end 20A resiliently comes in contact with the large-diameter portion 24. In the gasket 22 having the arrangement above-mentioned, when the gasket 22 is inserted into the large-diameter portion 24 of the exhaust hole 23, the winding end 20A at the outer periphery side is inwardly turned, causing the winding end 20A to resiliently come in contact with the large-diameter portion 24. Accordingly, the gasket 22 is so held as not to fall off from the exhaust hole 23 due to vibration or the like. It is therefore not necessary to support the gasket 22 with the hand or a jig until a flange portion 25A of an exhaust pipe 25 comes in contact with the gasket 22. This advantageouly improves the workability of attachment of the gasket 22 and the exhaust pipe 25. In the conventional gasket 22 above-mentioned, however, there is a likelihood that a portion of the gasket 22 protrudes into the exhaust pipe 25 in a state where the gasket 22 is properly installed. If a portion of the gasket 22 protrudes into the exhaust pipe 25, the protruding portion is deteriorated or damaged, causing the gasket 22 to be decreased in sealing properties in a short period of time. From GB-A-721 040 it is known to provide a solid positioning member which is attached to the inner side of a spiral wound gasket. The solid member increases the weight of the gasket considerably. Summary of the Invention To overcome the defects above-mentioned, the object of the present invention is to provide a spiral wound gasket which is so arranged as to prevent a portion thereof from protruding to restrain the gasket from being deteriorated or damaged, thereby to assure high sealing properties for a long period of time, which may be readily positioned for alignment to improve the workability of attachment, and which may be economically made in a lightweight design. It is another object of the present invention to provide a spiral wound gasket of which productivity may be readily improved to further lower the production cost. The present invention achieves the objects above-mentioned with a spiral wound gasket as claimed in claim 1. When the spiral wound gasket having the arrangement above-mentioned according to the present invention is used as disposed at fit-joint-type pipe connection portions of, for example, the exhaust pipe system in a motor vehicle, the annular body comes in contact with the outer peripheral surface of the up-stream-side exhaust pipe including a fit joint. Accordingly, the annular body serves as a centering member, thereby to prevent the gasket body from protruding into the fit joint. This considerably prevents the gasket body, in particular the filler material, from being deteriorated or damaged due to high-temperature gas. Accordingly, the gasket may assure, in its entirety, high sealing properties for a long period of time. Further, when the inner diameter of the annular body is set to a predetermined size according to the diameter of the fit joint, the spiral wound gasket may be automatically aligned and positioned with respect to the fit joint merely by putting the annular body on the fit joint. This improves the workability of attachment of the gasket. Further, the inner peripheral surface of the gasket body and the annular body form an annular closed space, thus making the entire gasket in a lightweight design. The body of the spiral wound gasket may have a corrugated section and may be provided at the inner and outer periphery portions thereof with waste wound portions where only the metal hoop material is wound by plural times. Since the gasket body has a corrugated section, the gasket has sufficient strechability in the axial direction so that both end surfaces of the gasket body in the axial direction resiliently come in contact with the surfaces of members to be sealed, thereby to assure high sealing properties. Further, since the gasket body is provided at the inner and outer peripheral portions thereof with waste wound portions where the metal hoop material is wound by several times, the gasket body is increased in shape retention strength. This further improves the workability of attachment of the gasket as aligned and positioned. According to the present invention, the spiral wound gasket may be made such that the metal hoop material having a V- or U-shape section forming the annular body and the metal hoop material having a corrugated section forming the gasket body, are integrally molded in a continuous manner. In this case, a single metal hoop material may be molded by rolls, while continuously fed, so as to have predetermined shaped sections as the metal hoop material forming the annular body and the metal hoop material forming the gasket body. It is therefore possible to manufacture, with good productivity, a spiral wound gasket excellent in workability of attachment. Accordingly, the increase in production cost may be restrained for the provision of the annular body. Other objects and effects of the present invention will be apparent from the following description made with reference to the attached drawings showing embodiments thereof. Brief Description of the Drawings Figure 1 is a vertical section view in front elevation of a spiral wound gasket in accordance with an embodiment of the present invention; Figure 2A is a plan view of an example of the material of an annular body; Figure 2B is a section view taken along the line IIA-IIA in Figure 2A; Figures 3 and 4 are plan views illustrating how to assemble the annular body with the gasket body; Figure 5 is a vertical section view in front elevation of an example of the use of the gasket shown in Figure 1; Figure 6 is a schematic side view of an example of apparatus for manufacturing the gasket of the present invention; Figures 7A and 7B are vertical section views in front elevation of the gaskets in accordance with another embodiments of the present invention; Figure 8 is an enlarged vertical section view of a portion of a conventional spiral wound gasket; and Figure 9 is a vertical section view of an example of the use of the conventional spiral wound gasket shown in Figure 8. Detailed Description of the Preferred Embodiments The following description will discuss embodiments of the present invention with reference to the attached drawings. Fig. 1 is a vertical section view of an embodiment of the present invention. In Fig. 1, a spiral wound gasket 1 comprises a gasket body 4 formed by winding, in the form of a spiral, a metal hoop material 2 and a filler material 3 as overlapping each other, and an annular body 5 serving as a centering member which is coaxially disposed at the inner periphery of the gasket body 4. In the gasket body 4, the metal hoop material 2 such as stainless steel is so molded as to have a corrugated section such as a W-shape section. At the inner peripheral surface of the gasket body 4, only the metal hoop material 2 is wound two to three times to form a waste wound portion 2a. Then, the filler material 3 having such characteristics as serving as a soft sealing material, overlaps the outer surface of the metal hoop material 2 outside with respect to the waste wound portion 2a. The metal hoop material 2 and the filler material 3 as overlapping each other are then wound in the form of a spiral. At the outer peripheral surface of the gasket body 4, only the metal hoop material 2 is wound two to three times to form a waste wound portion 2b. The winding starting end of the waste wound portion 2a at the inner periphery side and the winding terminal end of the waste wound portion 2b at the outer periphery side, are respectively secured to the adjacent waste wound portions 2a, 2b by, for example, spot welding. The annular body 5 is formed in the following manner. As shown in Figs. 2A and 2B, a metal hoop material having a V-shape section 2A is wound with the open ends thereof diametrically outwardly directed, such that both cut ends thereof overlap each other. The metal hoop material 2A thus wound is then fitted in the gasket body 4 at the inner periphery thereof as shown in Fig. 3. With the both cut ends abutting each other, the metal hoop material 2A then comes in contact with the inner peripheral surface of the waste wound portion 2a. Thus, the annular body 5 is integrally formed at the inner periphery of the gasket body 4. The metal hoop material having a V-shape section 2A and the inner peripheral surface of the waste wound portion 2a form an annular closed space 6 having a V-shape section (See Fig. 1). When the spiral wound gasket 1 having the arrangement above-mentioned is disposed, as shown in Fig. 5 for example, in the exhaust pipe system of a motor vehicle at its position defined by an upstream-side exhaust pipe 7, a flange 7A, a fit joint 7a forming a projecting portion at the terminal end of the upstream-side exhaust pipe 7 and a socket-type flange 8A of a downstream-side exhaust pipe 8, the spiral wound gasket 1 is mounted on the fit joint 7a with the annular body 5 coming in contact with the upstream-side exhaust pipe 7 having the fit joint 7a. Accordingly, the gasket 1 does not protrude into the socket-type flange 8A. This prevents the gasket body 4, in particular the filler material 3, from being deteriorated and damaged. Thus, the gasket 1 may assure high sealing properties for a long period of time. When the annular body 5 has such an inner diameter that the annular body 5 is put on the fit joint 7a of the upstream-side exhaust pipe 7 with no gap produced therebetween, the spiral wound gasket 1 may be automatically aligned and positioned with respect to the fit joint 7a merely by putting the annular body 5 on the fit joint 7a. This improves the workability of attachment. Further, since the inner peripheral surface of the gasket body 4 and the annular body 5 form the annular closed space 6 having a V-shape section, the gasket 1 may be made in a lightweight design. In the embodiment above-mentioned, the description has been made of the spiral wound gasket 1 made by a method comprising the steps of winding the metal hoop material having a V-shape section 2A with the open ends thereof diametrically outwardly directed such that both cut ends thereof overlap each other as shown in Figs. 2A and 2B, and fitting the metal hoop material 2A thus wound in the gasket body 4 at the inner periphery side thereof with the both cut ends abutting each other, as shown in Fig. 3, such that the metal hoop material 2A comes in contact with the inner peripheral surface of the waste wound portion 2a, thus forming the annular closed space 6 having a V-shape section by the metal hoop material having a V-shape section 2A and the inner peripheral surface of the waste wound portion 2a, so that the annular body 5 serving as a centering member is disposed. However, the spiral wound gasket 1 in accordance with the present invention may be alternatively made by the following manner. That is, there are disposed, as shown in Fig. 6, first molding rolls R1 which are adapted to so mold the metal hoop material 2 as to have a W-shape section and which are movable in both directions toward and away from each other, and second molding rolls R2 which are adapted to so mold the metal hoop material 2 as to have a V-shape section and which are moable in both directions toward and away from each other, these molding rolls R1 and R2 being disposed in the metal hoop material conveying direction at a suitable spatial interval. With the first molding rolls R1 separated from each other and the second molding rolls R2 contacted with each other, the metal hoop material 2 is molded into the metal hoop material having a V-shape section 2A by the second molding rolls R2, and is then wound on a winding drum D by one to two times. Then, with the second molding rolls R2 separated from each other and the first molding rolls R1 contacted with each other, the metal hoop material 2 is so molded as to have a W-shape section and then wound two to three times to form the waste wound portion 2a at the inner periphery side. Accordingly, the metal hoop material having a V-shape section 2A and the inner peripheral surface of the waste wound portion 2a form the annular closed space 6 having a V-shape section, thus forming the annular body 5. Then, the filler material 3 is fed, and the filler material 3 as overlaping the metal hoop material 2 is wound in the form of a spiral by several times. Then, feeding the filler material 3 is stopped and only the metal hoop material 2 is wound two to three times to form the waste wound portion 2b at the outer periphery. After the metal hoop material 2 is cut, the winding terminal end of the waste wound portion 2b at the outer periphery is secured to the adjacent waste wound portion 2b by, for example, spot welding. Thus, there is formed the spiral wound gasket 1 having the gasket body 4 and the annular body 5 in a continuous manner. In the embodiment above-mentioned, the description has been made of the gasket in which the metal hoop material 2 forming the gasket body 4 has a W-shape section and the annular body 5 has a V-shape section. However, the metal hoop material 2 forming the gasket body 4 may have a round W-section and the annular body 5 may have a U-shape section, as shown in Fig. 7A. Alternatively, both the metal hoop material 2 forming the gasket body 4 and the annular body 5 may have V-shape sections, as shown in Fig. 7B.

Claims: A spiral wound gasket (1) which is to be used as disposed at pipe connection portions (7A, 8A) fitted and connected to each other through a fit joint and which is formed by winding, in the form of a spiral, a metal hoop material (2) and a filler material (3) as overlapping each other, said spiral wound gasket (1) comprising an annular body (5) serving as a centering member integrally disposed at the inner periphery side of the gasket body (4) in which said metal hoop material (2) and said filler material (3) overlap each other, characterized in that the annular body (5) is made of a metal hoop material (2) having a V-shape or a U-shape section and is fitted, with open ends thereof diametrically outwardly directed and both cut ends abutting each other, in the gasket body (4) at the inner periphery side thereof such that said annular body (5) comes in contact therewith, said annular body (5) being made in a unitary structure with said gasket body (4). A spiral wound gasket according to claim 1, wherein the gasket body (5) has a corrugated section and is provided at the inner and outer peripheral portions thereof with waste wound portions (2a, 2b), where only the metal hoop material (2) is wound by plural times. A spiral wound gasket according to claim 1, wherein the metal hoop material (2) having said V-shape or said U-shape section which forms the annular body (5), and the metal hoop material (2) having a corrugated section which forms the gasket body (4) are integrally molded in a continuous manner.

Inventors: HAMADA EIICHI, HANGEISHI SUEKICHI, NISHIWAKI SHOICHI, OKADA KEIJI, SHIMOJI KOJI, UEDA TAKAHISA, YASHIMA MAMORU, HAMADA, EIICHI, HANGEISHI, SUEKICHI, NISHIWAKI, SHOICHI, OKADA, KEIJI, SHIMOJI, KOJI, UEDA, TAKAHISA, YASHIMA, MAMORU
Applicants: NIPPON PILLAR PACKING, NIPPON PILLAR PACKING CO. LTD.
Application year: 1991
Main classification: F16J15
IPC codes: F16J15