JP4580631B2 - Cylinder head gasket - Google Patents

Description

  The present invention relates to a cylinder head gasket interposed between a cylinder block and a cylinder head, and more specifically, a steel plate core and a compound material in which a fiber material is mixed in rubber are coated on both surfaces of the core metal. It is related with the cylinder head gasket comprised by the composite base material which consists of a compound layer formed in this way, and is interposed between a cylinder block and a cylinder head.

  This type of gasket is formed by coating the surface of a plate-shaped cored bar with a compound layer containing base fibers made of compressible inorganic fibers other than asbestos, rubber materials, and inorganic charge materials. Such a gasket is disclosed in Patent Document 1, for example. In this case, compared to a gasket that is simply coated with a rubber material on the core, there is less torque reduction when tightened between the cylinder block and the cylinder head, and the coating layer is difficult to peel off from the core. It has advantages such as high heat-resistant temperature.

In addition, if you want to obtain better airtightness in the cylinder head gasket, a bead that is a partially overlaid protrusion (projection) is formed around the target part (cylinder bore, etc.). It is known to be effective. Examples of such are disclosed in Patent Document 2 (see FIGS. 7 and 8), Patent Document 3, and Patent Document 4.
Japanese Patent Publication No. 06-084785 Japanese Utility Model Publication No. 62-077366 Japanese Patent Laid-Open No. 2003-083165 Japanese Utility Model Publication No. 5-03628

  Accordingly, the former gasket having a composite layer structure having a cored bar and a compound layer, that is, a rubber coat metal gasket in which the latter technique is added, that is, a rubber coat metal gasket in which a bead is formed in the compound layer. It was conceived that an excellent cylinder head gasket having the advantages of both of the above prior arts could be realized by making it.

  However, the rubber material containing fibers is clearly inferior to the rubber material only in the fluidity at the time of molding, so it is very difficult to integrally form the beads simultaneously with the compound layer as in the latter prior art. It was difficult and practically impossible. Therefore, as a rubber coated metal gasket with beads, as shown in FIG. 11, the compound layer 2 is coated on the front and back surfaces of the core metal 3 and processed into the form of the gasket 1, and the compound layers 2 and 2 are then processed into the core metal. 3, the bead portion 6 was formed in a convex shape.

  In this post-processing bead forming means, the cored bar 1 itself is bent, so that there is a drawback that the bead with a narrow width such as a thin protruding bead cannot be formed, and also due to the bending of the cored bar. There is room for improvement because it has poor usability, such as the use of small parts such as the reaction force is large and the fastening force between the cylinder block and cylinder head is small, and it is not applicable to small engines. there were.

  Accordingly, an object of the present invention is to provide a cylinder head gasket composed of a composite base material in which a fiber material mixed with a rubber material is coated on a core metal, and is subject to restrictions on the shape, size, and use location. However, it is to be realized as having a bead formed with a high degree of design freedom.

The structure of Claim 1 is comprised with the composite base material which consists of a steel sheet metal core, and the compound layer formed by coating the compound material with which the fiber material was mixed in rubber | gum on the both surfaces of the said metal core, In the cylinder head gasket interposed between the cylinder block and the cylinder head,
An annular groove is formed by compressing the compound layer at the position corresponding to the periphery of the cylinder bore in the composite base material, and a rubber material is inserted into the groove to form a bead that protrudes in the thickness direction from the compound layer. In the side portion of the groove, a step that is recessed in the thickness direction of the composite base material is formed,
The step is formed by compressing the compound layer on the side portion with a molding die, and the step is formed by compressing the compound layer on the side portion with a molding die. In this state, the bead is formed by injection molding a rubber material into the groove .

  According to the configuration of the first aspect, the formation of the compound layer and the bead is different from each other, and it is not necessary to simultaneously form the compound layer and the bead which are difficult to realize, and the bead is flowed during processing. Since a rubber material having excellent properties is used, the set shape can be formed smoothly without difficulty. The groove is formed by post-processing to compress the compound layer, and it is not necessary to consider the groove when forming the compound layer. Therefore, the formation of the compound layer by coating the core material with the compound material is special. It can be performed as usual without any processing, and the design of the groove shape and size can be easily changed. Accordingly, it is possible to form a bead having a complicated shape such as a narrow width or branching.

  Since the bead is formed by inserting a rubber material different from the compound material that is difficult to form into the groove, the shape and dimensions of the bead can be freely set. In addition, since the rubber material is inserted into the groove in three dimensions, the rubber material to be inserted is three-dimensionally in contact with the bottom surface and both side surfaces of the groove. It can be integrated.

  As a result, by compressing the compound layer, an annular groove is formed at a position corresponding to the periphery of the cylinder bore in the composite base material, and a bead is formed by inserting a rubber material into the groove. A Lindahead gasket that can realize a bead effective in maintaining hermeticity with a high degree of freedom in shape and size setting and flexibility in design, while also providing sufficient strength with the composite substrate. Could be provided.

Further , according to the configuration of the first aspect , a step that is recessed in the thickness direction of the composite base material is formed on the side portion of the groove, and this step exists in the vicinity of the lateral side of the bead. As a result, when the cylinder head gasket, that is, the bead is overcompressed due to the tightening force when it is assembled and tightened between the cylinder block and the cylinder head being more than specified, deformation due to overcompression The step functions as a refuge for the rubber material extruded in step (b).
Furthermore, according to the structure of claim 1, by providing a press portion for a step in a molding die for injection molding of a rubber material in the formed groove, the molding die is placed at a predetermined position with respect to the composite substrate. By the moving operation to be set to the side, the side portion can be compressed at the press portion to form a step. According to this, there is no need for a dedicated mold or process for forming a step, and it is possible to economically form a step effective as a relief in the rubber material during over-compression.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a cylinder head gasket 1 interposed between a cylinder block and a cylinder head in an engine. The cylinder head gasket 1 includes a core metal 3 made of a steel plate such as SPCC (cold rolled steel plate) and a compound material formed of a composite material in which a fiber material as a reinforcing material is mixed in rubber. It is constituted by a so-called double-sided rubber-coated metal gasket, which is formed by using a composite base material f composed of a compound layer 2 formed by coating both front and back surfaces.

  Fiber materials include glass fiber, ceramic fiber, rock wool, mineral wool, fused quartz fiber, chemically treated high silica fiber, molten oxalic acid alumina fiber, alumina continuous fiber, stabilized zirconia fiber, boron nitride fiber, alkali titanate fiber Inorganic fibers such as whiskers, carbon fibers, metal fibers, and boron fibers can be used. Also, aromatic polyamide fiber, polyamide fiber, polyolefin fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, polyester fiber, polyvinyl chloride fiber, polyurea fiber, polyurethane fiber, polyfluorocarbon fiber, phenol Organic fibers such as fibers and cellulosic fibers can also be used. In addition to the SPCC, various types such as a rolled steel plate such as SPHC, an aluminum plate, and a stainless steel plate can be used as the core metal 3.

  And as rubber (rubber material), nitrile rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), butadiene rubber (BR), butyl rubber (IIR), ethylene-propylene rubber (EPM), fluoro rubber (FPM), silicone rubber (Si), chlorosulfonated polyethylene (CSM), ethylene vinyl acetate rubber (EVA), chlorinated polyethylene (CPE), butyl chloride rubber (CIR), epichlorohydrin rubber (ECO), nitrilo Isoprene rubber (NIR), natural rubber (NR), etc. can be used. In addition, these rubber materials, for example, oil-extended rubber obtained by adding naphthenic process oil to SBR can also be used.

  Here, a method of manufacturing the cylinder head gasket 1 shown in FIGS. 1 and 2 will be briefly described. As shown in FIG. 6, a rolling roll method using upper and lower rotating rolls 31 and 32 is used for the composite base material f that is a raw material of the cylinder head gasket 1. That is, by sandwiching the core metal 3 between the upper and lower rolls 31 and 32 and rotating the rolls 31 and 32 while feeding the fluidized compound material 20 between the rolls 31 and 32 and the core metal 3, On the lower side in the rotational direction of each roll 31, 32, a compound material 20 having a predetermined thickness is coated on both surfaces of the core metal 3 to be formed into a composite base material f that becomes the compound layer 2 and sent out. come.

  Then, after taking out the plate-shaped composite base material f formed into a roll and extending it into a plate shape, as shown in FIG. 7, punching press forming and press forming for each hole processing are performed to form a predetermined shape. The obtained cylinder head gasket 1 is obtained.

  1 and 2, 4 is a large circular hole for a combustion chamber, and a large number of 5 are cooling holes for passing cooling water, and a portion around the large circular hole 4 that requires particularly high airtightness (that is, Regarding the cylinder bore peripheral position), an annular bead 6 surrounding the large circular hole 4 is formed into a double-sided bead structure formed on both the front and back compound layers 2.

  Next, the bead 6 will be described. The bead 6 is formed by a groove forming process and an injection process. As shown in FIG. 3, the groove forming step is a step of forming the groove m by compressing the compound layer 2 at the position corresponding to the cylinder bore periphery in the composite base material f. That is, in the groove forming step, the cylinder head gasket 1 is set between the upper and lower press dies 7 as shown in FIG. 3A in a state where the compound layer 2 is coated flat on both surfaces of the cored bar 3. To do. Each of the upper and lower press dies 7 is provided with a protrusion 7A for forming a groove.

  Next, as shown in FIG. 3 (b), the upper and lower press dies are moved up and down in a direction approaching each other, and the protrusions 7A are bitten into the front and back compound layers 2 to be compressed, as shown in FIG. 3 (c). As shown, when the vertically symmetrical press dies 7 are released, ring-shaped grooves m having a predetermined depth can be formed in the front and back compound layers 2.

  The groove formation by this compression takes advantage of the characteristics of the compound material in which the fiber material is mixed in the rubber, that is, the improvement of the compressibility retention. Since the compound material has the property that it can be plastically deformed by compression, if the compound layer is compressed in the thickness direction with a mold to form a groove, the groove can be maintained even after the mold is released.

  As shown in FIG. 4, the injection process is a process in which an unvulcanized rubber material is inserted into the groove m by injection molding using the upper and lower molding dies 8. That is, as shown in FIG. 4A, the upper and lower molding dies 8 to be used have a vertically symmetric shape and will be described with the upper molding dies 8. As shown in FIG. 4, the upper molding die 8 includes a protruding mold portion 9 on both sides at a position corresponding to the groove m, and an annular recessed mold portion located between the protruding mold portions 9. 10 are formed.

  Each protruding die 9 protrudes outward (downward in FIG. 4) from the reference press surface 11, and each protruding die 9 has a shape in which the cross-sectional shape protrudes in a substantially rectangular shape, and is a compound layer. 2 is formed in a range reaching the side portions 2b on both sides of the groove m. And the recessed mold part 10 recessed inward (upward in FIG. 4) rather than the reference | standard press surface 11 is set to the shape where the top part was recessed with circular arc shape.

  The procedure for forming the bead 6 in the injection process is as follows. First, as shown in FIG. 4A, a cylinder head gasket 1 in which a ring groove m is formed is prepared between upper and lower molding dies 8 and 8. Next, as shown in FIG. 4 (b), the upper and lower molding dies 8, 8 are moved closer to each other, and the reference press surface 11 is forcibly moved to a limit position where the reference press surface 11 slightly contacts the outer surface 2 a of the compound layer 2. Let At this time, each protruding mold portion 9 is positioned in the groove m and bites into each side portion 2b, and compresses both side portions 2b in the vertical direction.

  Then, unvulcanized rubber material 30 is injected and charged into the space surrounded by the upper and lower molding dies 8 and the compound layer 2 at the position of the groove m, and thereafter, as shown in FIG. As shown, the cylinder head gasket 1 in which the beads 6 are formed can be created by releasing the upper and lower molding dies 8 and using the rubber material 30 that has entered the recessed mold part 10. Thus, if the rubber material 30 is injected while compressing the side portions 2b of the groove m in the compound layer 2, the injected rubber material 30 wraps between the compound layer 2 and the mold 8 (so-called phenomenon). It is convenient to eliminate (around rubber).

  The compression rate of each side portion 2b is desirably 30% or more, so that a new concave groove (an example of a “step” in claim 2) om can be clearly formed in the vicinity of the bead 6, so that the cylinder block When the bead 6 is over-compressed between the cylinder head and the cylinder head, there is an advantage that the concave groove om functions as a refuge for the extruded rubber material 30. In the present embodiment, the step om is formed by compressing the compound layer 2 of the side portion 2b with the molding die 8 when the bead 6 is formed by injection molding the rubber material 30 into the groove m. (Claim 4).

  Thereafter, as shown in FIG. 5 (a), the cylinder head gasket 1 taken out from the mold is vulcanized by, for example, putting it in the vulcanizing pot 16, and the rubber material 30 and the compound layer 2 are vulcanized. Stabilize shape and composition. In this way, the compound layer 2 is compressed to form a groove, and the rubber material 30 is inserted into the groove by injection molding so that the bead 6 is formed [FIG. 5B and FIG. 1 reference].

  In addition, with the adhesive applied to the bottom surface of the groove m, the rubber material 30 is inserted into the groove m, whereby the adhesive is heated by the heat of the rubber material 30 to accelerate the curing, and the compound layer 2 Heat bonding (sometimes referred to as “baking bonding”) in which the rubber material 30 is firmly bonded and integrated can be performed. Further, depending on the type of the adhesive, it is possible to perform vulcanization adhesion by firmly bonding and integrating the core metal 3 and the rubber material 30 by heat during the vulcanization treatment shown in FIG.

  The step om may be formed by compressing the compound layer 2 of the side portion 2b with the press mold 12 for forming the groove when the compound layer 2 is compressed to form the groove m. 3). That is, as shown on the upper side with respect to the cylinder head gasket 1 in FIGS. 8 and 9, the small protrusions 14 for forming a step are formed on both sides of the groove forming protruding mold part 13 of the upper press mold 12. Then, the step om is formed simultaneously with the formation of the groove m (see FIG. 8). Then, the rubber material 30 is injection-molded into the groove m using the molding die 8, and the bead 6 with a step (concave groove) om is formed on both sides (see FIG. 9).

As shown in the lower side of the cylinder head gasket 1 in FIGS. 8 and 9, the cylinder head gasket 1 has a structure in which the step om is formed within the range of the rubber material 30 injected for forming the beads 6. Things can be used. That is, the groove m is formed by the press die 7 as in the case of the present embodiment (see FIG. 8).
As the molding die 15 for injection molding, a mold in which small protrusions 17 for forming a step are formed on both sides of the recessed mold portion 16 for forming beads (see FIG. 9) is used. With this molding die 15, the cylinder head gasket 1 having a structure having a ring-shaped step (concave groove) om within the range of the rubber material 30 can be produced.

  As shown in the upper side of FIG. 10, the cylinder head gasket 1 may be one in which the step om does not exist in either the rubber material or the compound layer 2 on both sides of the bead 6. Further, as shown in the lower side of FIG. 10, a step om is formed by compression in the compound layer 2 on the side portion of the groove, and the width of the rubber material 30 is a small width corresponding to the width of the bead 6. The cylinder head gasket 1 having a structure may be used.

  As described above, the present invention is composed of a composite base material composed of a steel plate core and a compound layer formed by coating the front and back surfaces of the core with a compound material in which a fiber material is mixed in rubber. In the cylinder head gasket interposed between the cylinder block and the cylinder head, an annular groove is formed on the composite base material by compressing the compound layer at the position corresponding to the periphery of the cylinder bore, and a rubber material is formed in the groove. And a bead protruding in the thickness direction from the outer surface of the compound layer is formed.

  As a result, because it is a cylinder head gasket in which a rubber made of a single material without mixing other materials such as fiber material is inserted into a groove formed in the compound layer by post-processing, and a raised bead is formed, A rubber coated metal gasket made of a metal core coated with a surface layer is made of a rubber material that is easy to compress and deform and is effective for improving sealability, while making it difficult to peel and excellent production efficiency just by compression. It was possible to provide a cylinder head gasket that can respond to severe air tightness and pressure resistance requirements.

  If a step is provided on the side of the bead as in claim 2, the cylinder head gasket has a tightening force greater than a specified value when it is assembled and tightened between the cylinder block and the cylinder head. That is, when the bead is overcompressed, there is an advantage that the step functions as a refuge for the rubber material extruded by deformation due to the overcompression.

  As the means for forming the step, it is possible to form the step simultaneously with a press die for forming a groove as in claim 3 or to form the step by compression of a molding die for injection molding as in claim 4. Any of these means is advantageous in that it does not require a dedicated mold or process for forming a step and can be economically produced.

The partial top view which shows an example of the cylinder head gasket of this invention Sectional view along the line II in FIG. 1 (Example 1) (A) is a cross-sectional view immediately before grooving with a press die, (b) is a cross-sectional view in which a groove is compressed and formed by upper and lower press dies, and (c) is a diagram illustrating the release of the press die. Partial side view of cylinder head gasket in condition (A) is a cross-sectional view immediately before setting a molding die, (b) is a cross-sectional view showing an injection molding state, and (c) is a part of a cylinder head gasket in a state where the molding die is released. Side view (A) is a figure which shows a vulcanization | cure process, (b) is the whole perspective view of the cylinder head gasket in which the bead was formed. Principle diagram showing the manufacturing method of composite substrate Action diagram of punching cylinder head gasket shape from molded composite substrate Sectional drawing which shows another means for forming grooves (Examples 2 and 3) Sectional drawing which shows another implementation state of an injection process (Example 2, 3) Partial sectional view of a cylinder head gasket showing the structure of another bead portion (Example 4) Partial sectional view of a gasket showing a conventional bead structure formed by bending a mandrel

Explanation of symbols

2 Compound layer 2a Outer surface 3 Core metal 6 Bead 30 Rubber material f Composite base material m Groove om Step

Claims (1)

It is composed of a composite base material composed of a steel sheet metal core and a compound layer formed by coating a compound material in which a fiber material is mixed in rubber on both the front and back surfaces of the metal core, and a cylinder block and a cylinder head. A cylinder head gasket interposed therebetween,
An annular groove is formed on the composite substrate by compressing the compound layer corresponding to the periphery of the cylinder bore, and a rubber material is inserted into the groove to form a bead that protrudes in the thickness direction from the compound layer. And a step that is recessed in the thickness direction of the composite base material is formed on the side portion of the groove,
The step is formed by compressing the compound layer on the side portion with a molding die, and the step is formed by compressing the compound layer on the side portion with a molding die. A cylinder head gasket, wherein a bead is formed by injection molding a rubber material into the groove in a state.

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