Split-type gasket

Abstract: A split-type gasket comprising at least two gasket sections (12-15) formed with bolt holes (12a-15a) and arranged to be interconnected in the same plane at respective joints to form the gasket, in which each of said joints is formed by a protruding portion on one gasket section and a complementary recess in the other gasket section arranged to receive said protruding portion in interlocking fashion, one of the bolt holes of said one gasket section being located closely adjacent said protruding portion. The protruding portion and the complementary recess are shaped so as to help prevent leakage.

Description: This invention refers to a split-type gasket, particularly one configured in ring form and made from a soft material, such as an oil pan gasket to be applied to the contact surfaces between a cylinder block and an oil pan in an engine. As is well known, a gasket made of a sheet of asbestos containing a soft material, for example, can be punched out in one stroke by means of a punch die. As an antipollution measure, the use of a soft material free from asbestos is desirable, but sheet material of this type is expensive. In order to reduce the cost of a ring-shaped gasket of poor yield, an internal residue which has been punched out in ring form may be reused at times, but with remaining combination problems. Although it is known to form a gasket as a split-type, as illustrated in Fig. 5 of the accompanying drawings, and to apply liquid gasket material to junctions J1 and J2 when assembling it, leaks can easily occur at junction regions where there is a lower contact pressure, which is troublesome and time-consuming. Although it is known to connect respective parts of a split-type gasket through a piece which is formed with a bolt hole and is made of a different material, the combination of different materials raises other problems such as selection of gasket material and thickness, control of contact pressure and the clamping force of the bolt, and the like, and the presence of connecting areas on both sides of the piece concerned leaves a problem of numerous possible leakage points. It is also known from US-A-3231289 (Carrell) to provide a split-type gasket comprising at least two gasket sections formed with bolt holes and arranged to be interconnected in the same plane at respective joints to form the gasket, in which each of said joints is formed by a protruding portion on one gasket section and a complementary recess in the other gasket section arranged to receive said protruding portion in interlocking fashion. According to the present invention, one of the bolt holes of said one gasket section is located closely adjacent the said protruding portion, in the adjacent body of the said one gasket section, and the edge of the said protruding portion on the said one gasket section is formed, in the order now specified, on one side as a concave circular arc merging at its inner end with the body of the said one gasket section and merging at its outer end with a convex circular arc which forms the distal extremity of the protruding portion whereby said one side is S-shaped, said convex arc merging with a straight edge which forms the other side of the protruding portion and merges with the body of the gasket section by way of a further concave circular arc, and the edge of the said recess in the said other gasket section is complementarily shaped. With such an arrangement, in use of the gasket, the respective gasket sections are interconnected in a region of homogeneous gasket material closely adjacent a bolt, where the high and stable contact pressure provided by the bolt increases the reliability of the interlocking of the gasket sections, and prevents leakage. Preferably the distance from the distal extremity of the said protruding portion to the centre of the said adjacent bolt hole is not more than 23% of the spacing between the said bolt holes in the gasket sections. It is further preferred that an imaginary transverse line representing the inner end of the said protruding portion does not intersect the said adjacent bolt hole. Both of these factors contribute substantially to the reliability of the joint and the prevention of leakage in use of the gasket. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:- Fig. 1 is a plan view of a first embodiment of a split-type gasket according to the invention; Fig. 2 is a plan view of one section of a joint in the embodiment of Fig. 1; Fig. 3 is a plan view of the other section of the joint; Fig. 4 is a plan view of another embodiment of a joint; and Fig. 5 is a plan view of a known gasket. As illustrated in Fig. 1, a split-type gasket 11 comprises two straight gasket sections 12 and 13 and two U-shaped curved gasket sections 14 and 15, all provided with bolt holes 12a, 12b, etc., 13a, 13b, etc., 14a, 14b, etc., and 15a, 15b, etc. The straight sections 12 and 13 and curved sections 14 and 15 are connected together at joints 16 to 19. Figs. 2 and 3 show these joints, in particular joint 17 near bolt hole 12a by way of example. Here the joint section of Fig. 2 comprises a protruding portion with its edge formed by concave and convex circular arcs A-1 and B-1 which are mutually contiguous to form an S-shape, straight edge C-1, and concave circular arc D-1. Distance d between the distal extremity T-1 of the protruding portion and the center of bolt hole 12a is not more than 23% of bolt pitch P (see Fig. 1). Thus if P=80 mm and the ratio is 20%, then d=16 mm. Furthermore the arrangement is such that line X connecting points E-1 and F-1 at the inner end of the protruding portion, where circular arcs B-1 and D-1 meet the outside and inside edges of the gasket respectively, does not intersect bolt hole 12a. Referring to Fig. 3, the complementary recess in the other gasket section is made up of circular arcs G-1 and H-1, straight edge K-1 and circular arc L-1, all arranged to fit with the aforementioned circular arcs A-1 and B-1, straight edge C-1 and circular arc D-1, respectively. Thus, when the set of gasket sections 12 to 15 is assembled in a common plane on a mounting surface with joints 16 to 19 interconnected, and bolts are inserted through the various bolt holes, no separation of the gasket sections at the joints 16 to 19 can take place. Furthermore, since the contact pressure is sufficient and homogeneous material is used at the junctions, no leakage will occur. As shown in Fig. 4, one or both sides of the bolt hole may be laterally extended in the form of a circular arc, as at lines M and M, if the edge regions of the gasket on either side of the bolt hole would otherwise be so narrow that leakage might occur. It will thus be understood that the present invention, at least in its preferred forms, provides split-type gaskets which are not prone to leak even without liquid gasket application, with low costs of production in terms of both labour and materials, as well as improved yield.

Claims: A split-type gasket (11) comprising at least two gasket sections (12-15) formed with bolt holes and arranged to be interconnected in the same plane at respective joints to form the gasket, in which each of said joints is formed by a protruding portion on one gasket section and a complementary recess in the other gasket section arranged to receive said protruding portion in interlocking fashion, characterised in that one of the bolt holes of said one gasket section is located closely adjacent the said protruding portion, in the adjacent body of the said one gasket section, and in that the edge of the said protruding portion on the said one gasket section is formed, in the order now specified, on one side as a concave circular arc (B-1) merging at its inner end with the body of the said one gasket section and merging at its outer end with a convex circular arc (A-1) which forms the distal extremity of the protruding portion whereby said one side is S-shaped, said convex arc merging with a straight edge (C-1) which forms the other side of the protruding portion and merges with the body of the gasket section by way of a further concave circular arc (D-1), and the edge of the said recess in the said other gasket section is complementarily shaped. A gasket as claimed in claim 1, wherein the distance (d) from the distal extremity of the said protruding portion to the centre of the said adjacent bolt hole is not more than 23% of the spacing (P) between the said bolt holes in the gasket sections. A gasket as claimed in claim 1 or 2, wherein an imaginary transverse line (X) representing the inner end of the said protruding portion does not intersect the said adjacent bolt hole.

Inventors: FUKUSHIMA KOWA, MORITA YASUSHI, UCHIDA TADAMASA, FUKUSHIMA, KOWA, MORITA, YASUSHI, UCHIDA, TADAMASA
Applicants: TOKYO GASKET CO LTD, TOKYO GASKET CO., LTD.
Application year: 1992
Main classification: F02F11
IPC codes: F01M11, F16J15, F02F11