Metal gasket with a seal ring

Abstract: A metal gasket (C) of the invention is used for an internal combustion engine, especially for an engine with a cylinder liner (CL). The gasket (C) is formed of a first metal plate (C10) having a first hole greater than a hole of the engine, an annular ring (C11) and sealing means (C10a). The annular ring (C11) has an inner size substantially corresponding to the hole of the engine, an outer size substantially corresponding to the first hole, and a thickness greater than that of the first metal plate (C10). The annular ring (C11) is situated inside the first hole and attached to the first metal plate (C10). The sealing means (C10a) is formed on the gasket for providing a surface pressure outside the annular ring (C11). The annular ring (C11) has a plurality of engaging members (C14) slidably engaging the first metal plate (C10) in the first hole so that a position of the annular ring relative to the first metal plate is changed based on a condition of the engine to be installed.

Description: Background of the Invention and Related Art Statement The present invention relates to a metal gasket with a seal ring for use as a cylinder head gasket of an internal combustion engine. In an engine with a cylinder liner, the cylinder liner is installed inside a bore of a cylinder block. In this case, an upper end of the cylinder liner is provided with a flange, and the cylinder block has an annular recess, wherein the flange is placed in the annular recess of the cylinder block. It is designed that the upper end of the cylinder liner is flush with the upper surface of the cylinder block, but the upper end of the cylinder liner may be located slightly lower than the upper surface of the cylinder block. A gasket for the engine with the cylinder liner is disposed under the cylinder head and above the upper surface of the cylinder block and the upper end of the cylinder liner. If the upper end of the cylinder liner is lower than the upper surface of the cylinder block, a small space is formed between the cylinder head and the upper end of the cylinder liner. In this case, conventionally, the gasket has a fire ring around the cylinder bore to securely seal therearound, which makes the gasket inevitably thick. In case a thick gasket, such as a gasket with a fire ring, is not suitable for an engine, a gasket may be formed of one metal plate, such as Japanese Utility Model Publication No. 61-14748. In this gasket, the metal plate includes a bead and a sealing portion in a ring shape around the cylinder bore. The sealing portion is made thick with a thickness of 0.03-0.05 mm by plating, so that the sealing portion operates as a fire ring. Since the sealing portion made of plating is expensive and needs extra labor, the above gasket with the sealing portion is not appropriate. Therefore, a thin annular ring has been fixed by welding on a metal plate around a cylinder bore instead of forming the sealing portion by plating. When the gasket with the thin annular ring is installed between the cylinder head and the cylinder block and is tightened, the thin annular ring regulates a compressible height of a bead formed around the thin annular ring, and seals a space in case the upper end of the cylinder liner is located slightly lower than the upper surface of the cylinder block. However, when the above space is shallow or the surface pressure regulation height for the bead formed therearound is low, the thickness of the annular ring must be thin. In this case, it is difficult to prepare and fix the thin annular ring to the metal plate. Also, the processing cost becomes high. Further, in case the cylinder block is formed of light metal or alloy thereof in order to provide a light engine, since the rigidity of the cylinder block is lowered especially around the cylinder bore, if a high pressure is formed around the cylinder bore, the cylinder block may deform around the cylinder bore. In U.S. Patent No. 4,711,456, rings connected to each other are disposed in the cylinder bores, but the rings are covered by a cover member. Also, in U.S. Patent No. 4,754,982, a rubber ring is disposed around a fluid hole, not for a cylinder bore. These rings are not easily assembled with a main part of the gasket. Document FR 1.327.379 A discloses a metal gasket for an internal combustion engine having at least one hole to be sealed, the metal gasket comprising two plates and having a hole greater than the at least one hole to be sealed, both plates being held together by a metallic inset. Furthermore, the metal gasket comprises an annular ring having an inner size substantially corresponding to the at least one hole of the engine to be sealed and an outer size substantially corresponding to the hole of the two metal plates. The annular ring has preferably a V-shaped cross-section, the V-shaped section of the annular ring being pressed against the inner edges of both plates in order to improve the sealing ability of the metal gasket. Accordingly, one object of the invention is to provide a metal gasket with a seal ring, wherein the seal ring can be easily assembled with a metal plate. Another object of the invention is to provide a metal gasket with a seal ring as stated above, which is suitable to be installed in a narrow space or gap, such as between an upper end of a cylinder liner and an upper surface of a cylinder block. A further object of the invention is to provide a metal gasket with a seal ring as stated above, which can prevent deformation of a cylinder block in case rigidity of the cylinder block is not so strong. A still further object of the invention is to provide a metal gasket with a seal ring as stated above, which can easily and slightly regulate a surface pressure of a bead. Further objects and advantages of the invention will be apparent from the following description of the invention. Summary of the Invention According to the invention, these objects are achieved by a metal gasket according to claim 1. The dependent claims define preferred embodiments of the invention. A metal gasket of the invention is used for an internal combustion engine. The gasket is basically formed of a first metal plate extending substantially throughout an entire area of a gasket and having a first hole greater than a hole of the engine, and sealing means around the first hole. An annular ring is prepared to have an inner size substantially corresponding to the hole of the engine, an outer size substantially corresponding to the first hole, and a thickness greater than that of the first metal plate. The annular ring is situated inside the first hole and attached to the first metal plate. The sealing means provides a surface pressure on the first plate outside the annular ring. The sealing means and the annular ring securely seal around the hole of the engine when the gasket is compressed. Also, the annular ring has a plurality of engaging members slidably engaging the first metal plate in the first hole. As a result, a position of the annular ring relative to the first metal plate can be changed based on a condition of the engine to be installed. Also, the annular ring can be easily attached to the first metal plate. Each of the engaging members has upper and lower edges, and an inwardly curved surface between the upper and lower edges. Namely, the upper and lower edges are pressed so that the first metal plate is held between the upper and lower edges. The sealing means may be a bead formed on the first plate. In case the gasket is formed of a plurality of metal plates, the bead may be formed on the plate other than the plate with the annular ring. Brief Description of the Drawings Fig. 1 is a plan view of a part of a metal gasket which does not form part of the invention; Fig. 2 is an enlarged cross sectional view of the metal gasket taken along line 2-2 in Fig. 1; Fig. 3 is an explanatory sectional view of the metal gasket of Fig.1 and Fig.2, wherein the gasket is installed and compressed between a cylinder head and a cylinder block ; Fig. 4 is a sectional view, similar to Fig. 2, of a further metal gasket which does not form part fo the invention; Fig. 5 is a sectional view, similar to Fig. 2, of a first embodiment of a metal gasket of the invention; Fig. 6 is an enlarged view of a portion 6 in Fig. 5; Fig. 7 is an explanatory sectional view of the first embodiment of the gasket, wherein the gasket is installed and compressed between a cylinder head and a cylinder block; and Fig. 8 is a sectional view, similar to Fig. 5, of a second embodiment of a metal gasket of the invention. Detailed Description of Preferred Embodiments With reference to Figs. 1-3, a metal gasket A is shown. The gasket A is a cylinder head gasket to be installed in an engine with a cylinder head CH, a cylinder block CB and a cylinder liner CL. The gasket A includes a plurality of cylinder bores Hc, water holes Hw, oil holes Ho, bolt holes Hb and push rod holes Hp corresponding to those of the engine, as in the conventional gasket. The gasket A is formed of one metal plate A10, and a seal ring A11 situated inside the cylinder bore H. The inner size or diameter of the cylinder bore Hc is slightly greater than a cylinder bore of the engine, in which the seal ring A11 is disposed. The inner size of the seal ring A11 substantially corresponds to the cylinder bore of the engine. A bead A10a is formed on the meal plate A10 around the cylinder bore Hc. When the gasket is installed in the engine, the bead A10a is located on the cylinder block CB outside the cylinder liner CL. The seal ring A11 has an inner periphery A11a, an outer periphery A11b contacting the plate A10, and upper and lower surfaces A11c, A11d. The thickness or height of the inner periphery A11a is less than that of the outer periphery A11b. The upper and lower surfaces A11c, A11d are arranged symmetrically relative to a central plane thereof, and incline or taper toward the inner periphery A11a from the outer periphery A11b. The thickness t1 of the inner periphery A11a of the seal ring A11 is greater than the thickness t2 of the meal plate A10 to provide a high surface pressure at the seal ring A11. Preferably, the metal plate A10 is formed of a hard metal, such as SUS301H with a thickness of 0.3-0.6 mm, and the seal ring A11 is formed of a soft steel. The seal ring A11 is fixed to the metal plate A10 by spot welding at several portions. However, the seal ring A11 may be movably attached to the metal plate A10. The engine to which the gasket A is installed has the cylinder liner CL with a flange FL, while the cylinder block CB has an annular recess. When the cylinder liner CL is assembled with the cylinder block CB, the flange FL is located in the annular recess of the cylinder block CB. In this condition, the upper end of the cylinder liner CL is ideally flush with the upper surface of the cylinder block CB. However, the upper end of the cylinder liner CL is often located slightly lower than the upper surface of the cylinder block CB to thereby form a gap Δ therebetween. When the gasket A is installed in the engine, the seal ring All is located on the flange FL, and the bead A10a is located on the cylinder block CB. The distance between the lower surface A11d of the seal ring A11 and the lower surface of the metal plate A10 is greater than the gap Δ, so that the seal ring A1 can be interposed between the cylinder head CH and the cylinder liner CL without being affected by the plate A10 to securely seal around the cylinder bore. As shown in Fig. 3, when the gasket A is installed between the cylinder head CH and the cylinder Block CB and is tightened, the seal ring A11 provides a surface pressure P to seal around the cylinder bore Hc. Since the thickness of the seal ring A11 is increased from the inner periphery to the outer periphery, the surface pressure P gradually changes from the inner periphery to the outer periphery. In this case, since the high surface pressure is not formed immediately outside the cylinder bore, deformation of the cylinder bore is prevented. When the gasket A is tightened, the bead A10a is also compressed to securely seal around the cylinder bore Hc. Since the seal ring A11 slightly projects upwardly from the upper surface of the metal plate A10, when the gasket A is tightened, the bead A10a is not completely compressed. Namely, the seal ring A11 operates as a surface pressure regulation plate. Therefore, creep relaxation of the bead A10a is prevented. In the engine as shown in Fig. 3, since the annular recess where the flange FL is disposed is formed above an inner projection or flange of the cylinder block CB, a large tightening pressure is applied on the inner projection. However, since the tightening pressure is applied at a base of the projection, not an inner end close to the cylinder liner CL. Therefore, the deformation of the cylinder block is prevented. The gasket A can securely seal around the cylinder bore and absorb the gap Δ between the cylinder liner and cylinder block. Fig. 4 shows a further cylinder head gasket B. The gasket B includes a metal plate B10 and a seal ring B11, similar to the gasket A. However, the gasket B further includes an upper plate B12, and a lower plate B13 to sandwich the plate B10 and the seal ring B11 therebetween. Also, a bead B13a surrounding the seal ring B11 is formed in the lower plate B13. In the gasket B, if there is a gap between the cylinder liner and the cylinder block, though the seal ring B11 is not directly placed on the cylinder liner, the seal ring B11 can provide the gap to securely seal around the cylinder bore. The upper or lower plate may have a curved portion to cover the plates facing the cylinder bore. Figs. 5-7 show a first embodiment C of a metal gasket of the invention. The gasket C is formed of a metal plate C10 with a bead C10a, and a seal ring C11, similar to the gasket A. In the gasket C, however, the seal ring C11 is an annular ring with a rectangular cross section having upper and lower surfaces parallel to each other, and includes four engaging portions C14 equally spaced apart from each other. The thickness t1 of the seal ring C11 is greater than the thickness t2 of the metal plate C10. Each engaging portion C14 is formed by partly pressing the upper and lower surfaces C11c, C11d of the seal ring C11 to have a curved inner surface C14a with upper and lower edges C14b. The outer portions of the upper and lower surfaces of the seal ring 11 may be dented slightly in a rectangular shape to have dented upper and lower surfaces. The inner surface of the plate C10 contacts the curved inner surface C14a and is held between the upper and lower edges C14b. Therefore, the seal ring C11 can move inside the hole of the metal plate C10, but does not disengage from the metal plate C10. As shown in Fig. 7, when the gasket C is arranged between the cylinder head CH and the cylinder block CB with the cylinder liner CL, if there is a gap A between the upper end of the cylinder liner CL and the upper surface of the cylinder block CB, the seal ring C11 can move relative to the metal plate C10 when the gasket C is compressed. Therefore, the seal ring C11 and the metal plate C10 can be properly held between the cylinder head and the cylinder block without biasing force for connecting the seal ring C11 and the metal plate C10. The seal ring C11 and the bead C10a securely seal around the cylinder bore Hc. In the gasket C, since the bead C10a is not completely flattened by the seal ring C11, creep relaxation of the bead C10a is prevented. In the gasket A, it is explained that the seal ring A11 is fixed to the metal plate A10 by the spot welding. However, the seal ring A11 may have the engaging portions, as disclosed in the gasket C, to connect the seal ring A11 and the metal plate A10. Fig. 8 shows a second embodiment D of a cylinder head gasket of the invention. The gasket D includes a metal plate D10 and a seal ring D11, similar to the gasket C. However, the gasket D further includes an upper plate D12, and a lower plate D13 to sandwich the plate D10 and the seal ring D11 therebetween. Also, a bead D13a surrounding the seal ring D11 is formed in the lower plate D13. In the gasket D, if there is a gap between the cylinder liner and the cylinder block, though the seal ring D11 is not directly placed on the cylinder liner, the seal ring D11 can absorb the gap to securely seal around the cylinder bore. The upper or lower plate may have a curved portion to cover the plates facing the cylinder bore. While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.

Claims: A metal gasket (C, D) for an internal combustion engine having at least one hole (Hc) to be sealed, comprising: a first metal plate (C10, D10) extending substantially throughout an entire area of a gasket and having a first hole greater than an at least one hole of the engine, an annular ring (C11, D11) having an inner size substantially corresponding to the at least one hole of the engine, an outer size substantially corresponding to the first hole, and a thickness (t) greater than that of the first metal plate, said annular ring being situated inside the first hole and attached to the first metal plate, and sealing means (C10a, D13a) formed on the gasket for providing a surface pressure outside the annular ring, said sealing means and the annular ring securely sealing around the hole of the engine, said metal gasket (C, D) being characterized in that said annular ring (C11, D11) has a plurality of engaging members (C14) slidably engaging the first metal plate (C10, D10) in the first hole so that a position of the annular ring relative to the first metal plate is changed based on a condition of the engine to be installed. A metal gasket (C, D) according to claim 1, wherein each of said engaging members (C14) has upper and lower edges (C14b) and an inwardly curved surface (C14a) between the upper an lower edges, said first metal plate (C10, D10) being slidably held between the upper and lower edges. A metal gasket (C) according to claim 1 or 2, wherein said sealing means is a bead (C10a) formed on the first plate. A metal gasket (D) according to claim 1 or 2, further comprising at least one second metal plate (D13) having a second hole having a size substantially corresponding to the inner size of the annular ring, said sealing means being a bead (D13a) formed on the second metal plate.

Inventors: INAMURA SUSUMI, MIYAOH YOSHIO, INAMURA, SUSUMI, MIYAOH, YOSHIO, Inamura, Susumi c/o Ishikawaa Gasket co., Ltd., Miyaoh, Yoshio Ishikawa Gasket Co., Ltd
Applicants: ISHIKAWA GASKET, ISHIKAWA GASKET CO. LTD.
Application year: 1997
Main classification: F16J15
IPC codes: F16J15