JP2011190808A - Sealing structure by metal gasket and outboard motor equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing structure capable of preventing occurrence of corrosion on a mating surface of an engine body, by preventing invasion of cooling water into the mating surface of the engine body. <P>SOLUTION: A main bead 54 is formed in a portion corresponding to a central portion between a bore hole 41a or the like in a metal gasket 40 and a cooling water passage 26 or the like, and a sub-bead 55 is formed in a portion corresponding to a boundary portion between a mating surface between a cylinder body 22 and a cylinder head 23 in the metal gasket 40 and cooling water passages 26, 36. Further, the base material of the metal gasket 40 is composed of bead plates 51, 52 on which coating layers made of rubber are formed on their surfaces, and a shim member 53 disposed between the bead plates 51 and 52. A main bead 54 is formed by forming respective space portions between the bead plates 51 and 52 and the shim member 53. A sub-bead 55 is formed by forming a space portion in a predetermined portion between the bead plates 51 and 52. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a seal structure using a metal gasket configured by sealing a joint surface of an engine main body configured by assembling a separate cylinder head and cylinder body with a metal gasket, and an outboard motor equipped with the seal structure.

  The engine body that constitutes the outer part of the engine used in small ships is constructed by assembling a plurality of case members such as a cylinder head and a cylinder body. Cooling water infiltrates into the mating surface between the cylinder head and the cylinder body. A seal structure for preventing this is formed (for example, see Patent Document 1). This seal structure is configured by installing a metal gasket formed by forming a rubber layer on the surface of a thin plate base material made of stainless steel on the mating surface of the cylinder head and the cylinder body. A bead made of a ridge is formed in a portion along the periphery of the cooling water flow path in the metal gasket. The metal gasket provided with this bead is pressed by the mating surface of the cylinder head and the cylinder body to flow the cooling water. The cooling water of the road is prevented from entering the mating surface.

JP 2005-325895 A

  However, in the above-described seal structure, the portion where the bead is formed in the metal gasket is a portion corresponding to the substantially central portion in the width direction of both side portions sandwiching the cooling water flow path on the mating surface. The surface pressure received from the metal gasket is reduced at the road side portion, and cooling water may enter the portion between the cooling water flow path and the bead at the mating surface. In this case, in particular, when seawater is used as the cooling water, crevice corrosion may occur at the joint surface between the cylinder head and the cylinder body.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to prevent corrosion from occurring on the mating surface of the engine body by preventing the coolant from entering the mating surface of the engine body. To provide a metal gasket seal structure and an outboard motor equipped with the seal structure.

  In order to achieve the above-mentioned object, a structural feature of the seal structure by the metal gasket according to the present invention includes a plurality of cylinder forming recesses and a cooling water flow passage formed so as to surround the plurality of cylinder forming recesses. A sealing structure with a metal gasket that seals the mating surface by installing a metal gasket on the mating surface between the cylinder head and the cylinder body in the engine body, and between the cylinder forming recess and the cooling water flow path in the metal gasket. A main bead that protrudes toward the mating surface is formed in a portion corresponding to substantially the center, and the surface pressure is adjusted along the portions corresponding to both side edges of the boundary between the mating surface of the engine body and the cooling water flow path in the gasket. A trapezoidal sub-bead with a bent portion that protrudes toward the edge of the cooling water flow path and the mating surfaces on both sides so that the peak appears. Form and is to prevent the entry into between mating surfaces of the cooling water of the cooling water flow path.

  In the seal structure with the metal gasket according to the present invention configured as described above, the metal located at the approximate center between the cylinder forming recess and the coolant flow path at the mating surface between the cylinder head and the cylinder body formed in the engine body. In addition to providing a main bead at a predetermined portion of the gasket, a sub-bead is formed at a portion corresponding to the boundary between the mating surface of the cylinder head and the cylinder body and the cooling water flow path in the metal gasket. Therefore, the surface pressure received from the metal gasket at the boundary between the mating surface of the cylinder head and the cylinder body and the cooling water flow path, which becomes the inlet when the coolant enters between the mating surfaces of the cylinder head and the cylinder body, is large. Thus, it is possible to reliably prevent the cooling water from entering between the mating surfaces of the cylinder head and the cylinder body. In the present invention, the metal gasket is preferably composed of a base material made of thin plate-like stainless steel.

  In addition, another structural feature of the sealing structure using the metal gasket according to the present invention is that the base material is disposed in a portion where at least a main bead is formed between two stacked bead plates and the two bead plates. A main bead is formed by forming a space between each of the two bead plates and the inner member, and between each of the two bead plates and the inner member or 2 The secondary bead is formed by forming a space in a predetermined portion between the bead plates.

  According to this, since the main bead and the sub bead in which the space portion is formed in the metal gasket acts like a spring or a cushion, the portion corresponding to the main bead and the sub bead on the mating surface of the cylinder head and the cylinder body. As a result, the surface pressure of the cylinder head and the cylinder body is more reliably sealed. Further, since the main bead is constituted by the two bead plates and the inner member, the seal between the cylinder forming recess and the cooling water flow path becomes more reliable. Moreover, although the inner member may or may not be provided in the sub-bead portion of the metal gasket, the sub-bead can be formed more firmly by providing the inner member.

  Further, another structural feature of the seal structure using the metal gasket according to the present invention is that a coating layer made of rubber is formed on the surface of the base material. According to this, the sealing performance of the metal gasket can be further improved.

  Still another structural feature of the metal gasket sealing structure according to the present invention is that a gap filler is applied to at least a portion of the surface of the metal gasket where the sub-bead is formed. According to this, the mating surface between the cylinder head and the cylinder body and at least the surface of the sub-bead of the metal gasket that contacts the mating surface are more closely adhered to each other. The seal is more secure. In addition, a gap may occur at the mating surface between the cylinder head and the cylinder body due to the rigidity of the engine, but it may not be possible to prevent the coolant from entering the mating surface simply by providing a bead on the metal gasket. In order to reliably prevent this intrusion, a gap filler is applied to a portion where the intrusion of cooling water is likely to occur.

  A feature of the outboard motor according to the present invention is that the engine body is an engine body included in the outboard motor, and includes the above-described seal structure using the metal gasket. According to this, it is possible to obtain an outboard motor that can reliably seal the mating surface between the cylinder head and the cylinder body.

It is the side view which showed the outboard motor provided with the sealing structure by the metal gasket which concerns on one Embodiment of this invention. It is sectional drawing which showed the engine. It is the top view which showed the metal gasket. It is sectional drawing which showed the metal gasket. FIG. 5 is a sectional view taken along line 5-5 in FIG. 3. FIG. 6 is a sectional view taken along line 6-6 in FIG. 3. FIG. 7 is a sectional view taken along line 7-7 in FIG. 3. FIG. 8 is a cross-sectional view taken along 8-8 in FIG. 3. It is sectional drawing which showed the state which installed the metal gasket between the cylinder body and the cylinder head. It is explanatory drawing which showed the surface pressure of each part shown in FIG. It is explanatory drawing which showed the surface pressure of each part in a conventional product. It is the top view which showed the metal gasket with which other embodiment is provided. It is 13-13 sectional drawing of FIG. It is 14-14 sectional drawing of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an outboard motor 10 having a seal structure with a metal gasket according to the embodiment. The outboard motor 10 includes a swivel bracket 11 and a clamp bracket 12 that is connected to the swivel bracket 11 and supports the outboard motor 10 via the swivel bracket 11. The swivel bracket 11 is assembled with a steering shaft (not shown) which is rotatable about the axis with the axial direction being substantially vertical, and the swivel bracket 11 is connected to the outboard motor 10 via the steering shaft. Is connected to the approximate center of the front side (the side on the forward direction side of the ship).

  For this reason, the outboard motor 10 can rotate in a horizontal plane with respect to the swivel bracket 11. The clamp bracket 12 is detachably attached to the rear tail (not shown) of the hull, and the upper end portion of the swivel bracket 11 is connected to the upper end portion of the clamp bracket 12 via a tilt shaft 12a. Yes. That is, the clamp bracket 12 is composed of a pair of members arranged at a predetermined interval in the left-right direction of the hull, and the tilt shaft 12a is horizontally stretched over the upper end portion of the clamp bracket 12 composed of the pair of members. ing. The upper end portion of the swivel bracket 11 is attached between a pair of members constituting the clamp bracket 12 on the tilt shaft 12a so as to be rotatable around the axis of the tilt shaft 12a.

  A housing that forms the outer surface of the outboard motor 10 includes a cowling 13 that includes a top cowl 13a and a bottom cowl 13b that constitute an upper side portion, an upper case 14 that constitutes a central portion, and a lower case that constitutes a lower side portion. 15. An engine 16 is housed inside the cowling 13, and a screw 17 is provided in the lower case 15. The upper case 14 houses a power transmission mechanism including a drive shaft 18 that transmits the driving force of the engine 16 to the screw 17.

  The engine 16 is a water-cooled engine having three cylinders, and a crankshaft 16a extending in the vertical direction is disposed inside. A drive shaft 18 is connected to the lower end of the crankshaft 16a. For this reason, when the engine 16 is driven, the crankshaft 16 a rotates and the rotational force is transmitted to the screw 17 via the drive shaft 18. A propulsive force is generated by the rotation of the screw 17. A cooling water pump 19 is installed at the lower end of the upper case 14, and a water intake 19 a for taking in cooling water (seawater) is formed in the lower case 15. Then, by operating the cooling water pump 19, the cooling water can be taken in from the water intake 19 a, and the cooling water can be sent to the engine 16 to cool the engine 16.

  The engine 16 is configured as shown in FIG. The outer portion constituting the main body portion of the engine 16 is configured by assembling the cylinder body 22 and the cylinder head 23 on the upper portion (the upper portion in FIG. 2) of the crankcase 21 in which the crankshaft 16a is accommodated. The main body portion of the engine 16 is made of aluminum. Three cylindrical cylinders 24 (only one is shown) constituting the cylinder forming recess of the present invention are formed side by side at a substantially central portion inside the cylinder body 22. The piston 25 connected to the crankshaft 16a via the connecting rod 25a is accommodated in the state which can move up and down. The vertical movement of the piston 25 is transmitted to the crankshaft 16a, and the crankshaft 16a rotates.

  Further, a cooling water passage 26 is formed in an upper side portion around the cylinder 24 in the cylinder body 22, and an exhaust passage is provided outside one side portion (left side portion in FIG. 2) of the cooling water passage 26 in the cylinder body 22. 27 is formed. A cooling water passage 28 is also formed around the exhaust passage 27. In addition, three combustion chambers 31 (only one is shown) communicating with each cylinder 24 are formed in the lower center of the cylinder head 23, and an intake valve 32 and an exhaust valve are formed above each combustion chamber 31. 33 is provided. An intake port 32a communicating with the intake valve 32 of each cylinder 24 is connected to an intake device including a carburetor 34, an intake pipe 35 and the like, and an exhaust port 33a communicating with the exhaust valve 33 is an exhaust device including an exhaust passage 27 and the like. It is connected to the.

  The intake valve 32 opens during intake and sends a mixed gas of air supplied from an intake device and fuel supplied from a fuel tank (not shown) into the cylinder 24, and the exhaust valve 33 is exhausted. And the exhaust gas discharged from the cylinder 24 is sent to the exhaust device. The engine 16 also includes an ignition device (not shown), and the air-fuel mixture explodes by ignition of the ignition device. And by this explosion, piston 25 moves up and down, and the crankshaft 16a rotates by the movement.

  Further, a cooling water flow path 36 communicating with the cooling water flow path 26 is formed in a portion facing the cooling water flow path 26 in the lower part of the cylinder head 23, and a portion facing the cooling water flow path 28 in the lower part of the cylinder head 23 is formed. A cooling water passage 37 communicating with the cooling water passage 28 is formed. Further, a cooling water flow path 38 is also formed on one external side portion of the exhaust valve 33 in the cylinder head 23. These cooling water flow paths 26, 28, 36, 37, and 38 all communicate with each other to form one flow path, and the inside of this flow path is taken in from the water intake 19 a by the operation of the cooling water pump 19. The cooling water flows, and the engine 16 is thereby cooled. An oil passage (not shown) for supplying lubricating oil to the engine 16 is also formed in the main body portion of the engine 16.

  A metal gasket 40 is installed on the mating surface between the cylinder body 22 and the cylinder head 23. The metal gasket 40 is configured as shown in FIG. 3 in a plan view. In the portion corresponding to each cylinder 24, three bore holes 41a, 41b, 41c having the same size as the hole portion of the cylinder 24 are provided. The cylinders 24 are formed at the same interval. Further, a gas hole 42 having the same size as the hole of the exhaust passage 27 is formed in a portion corresponding to the exhaust passage 27 in the metal gasket 40.

  Then, small oval cooling water holes 43a, 43b, 43c, 43d, 43e are formed in a part of the peripheral portions of the bore holes 41a, 41b, 41c corresponding to the cooling water flow paths 26, 36 in the metal gasket 40. , 43f are formed at regular intervals. Further, elongated arc-shaped cooling water holes 44a, 44b, and 44c are formed at intervals around the gas holes 42 corresponding to the cooling water flow paths 28 and 37 in the metal gasket 40. . Further, cooling water holes 45a, 45b, and 45c having different sizes or shapes are formed in each end side portion of the metal gasket 40 excluding the gas hole 42 side.

  In addition, three substantially triangular oil holes 46a, 46b, 46c are formed in a row at regular intervals in a portion corresponding to the oil flow path in the metal gasket 40. And six bolt holes 47a, 47b, 47c, 47d, 47e, 47f, and 47g are formed at intervals in portions corresponding to the outer peripheral side portions of the cooling water flow paths 26 and 36 in the metal gasket 40. .

  Further, two through holes 48a and 48b are formed on both sides of the bolt holes 47e and 47f so as to sandwich the bolt holes 47e and 47f at substantially the same interval as the bolt holes 47e and 47f. Bolt holes 47a, 47b, 47c, 47d, 47e, 47f, and 47g are holes through which bolts (not shown) for connecting cylinder body 22 and cylinder head 23 are inserted, and through holes 48a. , 48b are holes through which positioning pins (not shown) for positioning the cylinder body 22 and the cylinder head 23 are inserted.

  As shown in FIG. 4, the metal gasket 40 in which various holes are formed as described above is used as an inner member of the present invention at a predetermined portion between the thin plate-shaped bead plates 51 and 52 arranged in a stacked manner. The thin plate-like shim member 53 is sandwiched. Each of the bead plates 51 and 52 and the shim member 53 is made of a stainless steel plate having a rubber coating layer (not shown) formed on the surface thereof, and each of the bead plates 51 and 52 has a thickness of about 0.2 mm. The thickness of 53 is set to about 0.1 mm.

  The bead plates 51 and 52 are vertically symmetrical (up and down in the state of FIG. 4), and protrusions 51 a, 51 b and 51 c projecting upward are formed on predetermined portions of the bead plate 51. In the predetermined portion of the bead plate 52, protrusions 52a, 52b, and 52c projecting downward are formed. The protrusions 51a and 52a are formed in a curved surface shape, and the protrusions 51b, 51c, 52b and 52c are formed in a trapezoidal shape with a bent portion. And the main bead 54 is formed with the protrusion 51a, the protrusion 52a, and the shim member 53 located in the inside thereof, and the auxiliary bead is formed with the protrusion 51b, the protrusion 52b, and a part of the shim member 53 located in the inside thereof. 55 is formed. Moreover, the half bead 56 which the edge part opened by the protrusion 51c and the protrusion 52c is formed.

  Such main beads 54, sub-beads 55, and half beads 56 are formed in a plurality of portions of the metal gasket 40 as shown in FIG. 5 is a cross section taken along line 5-5 in FIG. 3, FIG. 6 is a cross section taken along line 6-6 in FIG. 3, FIG. 7 is a cross section taken along line 7-7 in FIG. . As shown in FIG. 5, a shim member 53 is sandwiched between the ridge 51a and the ridge 52a at a portion along the peripheral edge of the bore holes (41a, 41b, 41c) in the metal gasket 40. A main bead 54 is formed.

  In addition, as shown in FIG. 6, the main bead 54 extends from the bore hole 41 a side to the peripheral portion at a portion between the bore hole 41 a (, 41 b, 41 c) in the metal gasket 40 and the peripheral portion of the metal gasket 40. The secondary bead 55 and the half bead 56 are formed in this order. In this case, as shown in FIG. 9, the sub-bead 55 includes the portion corresponding to the cooling water flow paths 26 and 36 in the metal gasket 40 and the edge side portion of the mating surface between the cylinder body 22 and the cylinder head 23 on both sides thereof. It is arranged to take. And the half bead 56 is arrange | positioned in the state which match | combined the open edge part with the edge part of the external side of the confronting surface of the cylinder body 22 and the cylinder head 23. FIG.

  At this time, the magnitude of the surface pressure applied to the mating surface of the cylinder body 22 and the cylinder head 23 by the main bead 54, the sub bead 55, and the half bead 56 is shown in FIG. In FIG. 10, the horizontal direction along the straight line a corresponds to each part of the metal gasket 40, and the vertical direction perpendicular to the straight line a indicates the magnitude of the surface pressure. The surface pressure of the portion on the straight line “a” is “0”, and the surface pressure increases as it protrudes downward from the straight line “a”. The higher the surface pressure, the better the sealing performance. According to this, a peak b having a large surface pressure appears in the main bead 54 portion, and a peak c smaller than the peak b appears in the half bead 56 portion. Further, small peaks d and e appear in the portions corresponding to the side edges of the cooling water flow paths 26 and 36, respectively.

  For reference, the surface pressure applied to the mating surface between the cylinder body 22 and the cylinder head 23 when a conventional metal gasket that is the same as the metal gasket 40 is used, except that the secondary bead 55 is not provided. The measurement results are shown in FIG. In this case, as in FIG. 10, a peak b having a large surface pressure appears in the main bead 54 portion and a peak c smaller than the peak b appears in the half bead 56 portion. No peak other than the contact pressure with the edge portion appeared in the portion corresponding to the edge portion. From this result, by providing the sub bead 55 like the metal gasket 40, the sub bead 55 is pressed against the vicinity of both side edge portions of the cooling water flow paths 26 and 36 on the mating surface of the cylinder body 22 and the cylinder head 23. It can be understood that the surface pressure of the cylinder body 22 and the cylinder head 23 can be positively applied, and cooling water can be prevented from entering the mating surface of the cylinder body 22 and the cylinder head 23.

  In addition, as shown in FIG. 7, four half beads 56 alternately change the direction from the peripheral edge of the metal gasket 40 to the inner peripheral edge of the bolt hole 47 f through the oil hole 46 b. Is formed. That is, each half bead 56 is disposed with its open end positioned at the peripheral edge of the metal gasket 40, the inner peripheral edge of the oil hole 46b, and the bolt hole 47f. Further, as shown in FIG. 8, the three half beads 56 change the direction of each other from the inner peripheral edge of the gas hole 42 to the outer peripheral edge of the metal gasket 40 through the cooling water hole 44 b. Is formed.

  In this case, each half bead 56 is disposed with its open end positioned at the peripheral edge of the metal gasket 40 and the inner peripheral edge of the cooling water hole 44b. Further, a portion where the bead plates 51 and 52 are joined is disposed at a portion corresponding to the inner peripheral edge portion of the gas hole 42 in the metal gasket 40. As described above, the main bead 54 is formed at a portion corresponding to the central portion between the bore holes 41a, 41b, 41c and the cooling water flow paths 26, 36, which require the most sealing performance in the metal gasket 40, and the cooling water flow The cooling water in the passages 26 and 36 is prevented from entering the bore holes 41a, 41b and 41c through the mating surfaces of the cylinder body 22 and the cylinder head 23.

  Further, a sub-bead 55 is formed in a portion corresponding to the cooling water flow paths 26 and 36 in the metal gasket 40 and a portion on the edge side portion of the mating surface between the cylinder body 22 and the cylinder head 23 on both sides thereof. Cooling water is also prevented from entering between the mating surfaces of the body 22 and the cylinder head 23. Further, half beads 56 are formed in other portions of the metal gasket 40 that require sealability so that proper sealing according to each portion can be performed.

  As described above, in the seal structure using the metal gasket according to the present embodiment, the main bead 54 is provided in a portion corresponding to the central portion between the bore holes 41a, 41b, 41c and the cooling water flow paths 26, 36 in the metal gasket 40. In addition to the formation, a sub-bead 55 is formed at a portion corresponding to the boundary between the joining surface of the cylinder body 22 and the cylinder head 23 and the cooling water flow paths 26 and 36 in the metal gasket 40. Therefore, the surface pressure of the edge side portion of the mating surface between the cylinder body 22 and the cylinder head 23 increases, and it is possible to reliably prevent the coolant from entering between the mating surfaces of the cylinder body 22 and the cylinder head 23.

  Further, since the metal gasket 40 is formed by forming a coating layer made of rubber on the surface of a thin plate-like stainless steel base material, it is made of seawater due to scratches on the mating surface between the cylinder body 22 and the cylinder head 23. Cooling water can be prevented from penetrating into the mating surface between the cylinder body 22 and the cylinder head 23. Further, the base material of the metal gasket 40 is composed of two bead plates 51 and 52 and a shim member 53 disposed in a portion forming the main bead 54 between the bead plates 51 and 52, Since the main bead 54 is formed by forming a space between the shim member 53 and the shim member 53, the surface pressure of the portion corresponding to the main bead 54 between the mating surfaces of the cylinder body 22 and the cylinder head 23 increases. The seal between the bore holes 41a, 41b, 41c and the cooling water passages 26, 36 is ensured.

  Further, since the auxiliary bead 55 is formed by forming a space in a predetermined portion between the two bead plates 51 and 52, the space between the mating surfaces of the cylinder body 22 and the cylinder head 23 and the cooling water flow paths 26 and 36 are formed. The surface pressure of the portion corresponding to the sub-bead 55 in the boundary portion is also increased, and the cooling water in the cooling water flow paths 26 and 36 can be prevented from entering between the mating surfaces of the cylinder body 22 and the cylinder head 23.

  Moreover, FIG. 12 has shown the metal gasket 60 with which the sealing structure by the metal gasket which concerns on other embodiment of this invention is provided. The metal gasket 60 is configured by applying a gap filler to predetermined portions on the front and back surfaces of the same metal gasket as the metal gasket 40. Therefore, the same parts as those of the metal gasket 40 will be described using the same reference numerals. In this metal gasket 60, the gap filler layer 61 surrounds the cooling water passages 26, 36 at the boundary between the joint surface of the cylinder body 22 and the cylinder head 23 and the cooling water passages 26, 36 and the front and back surfaces in the vicinity thereof. (The gap filler layer on the back side is not shown).

  Further, cooling water holes 44 a, 44 b, 44 b, 44 b, 44 b, 44 b, 44 b, 44 b, 44 b, 44 b, 44 b, 44 c at the boundary between the mating surface of the cylinder body 22 and the cylinder head 23 in the metal gasket 60. Gap filler layers 62, 63, and 64 (a back side gap filler layer is not shown) are formed so as to surround 44c. 13 shows a cross section 13-13 of FIG. 12, and FIG. 14 shows a cross section 14-14 of FIG. That is, the gap filler layers 61, 62, 63, 64 are formed on the surface of the sub-bead 55 or the half bead 56, respectively. For this reason, the mating surface of the cylinder body 22 and the cylinder head 23 and the sub-bead 55 or the half bead 56 contacting the mating surface via the gap filler layers 61, 62, 63, 64 are more closely attached. Thus, the sealing by the metal gasket 60 is further ensured. Other functions and effects of the metal gasket 60 are the same as those of the metal gasket 40 according to the above-described embodiment.

  Moreover, the sealing structure by the metal gasket which concerns on this invention is not restricted to embodiment mentioned above, It can implement by changing suitably. For example, in the above-described embodiment, the secondary beads 55 and 75 are constituted by the long ridges 51 b and 51 b or the ridges 71 b and 71 b and the plate inner 73. , 36, etc., each having a short length formed on one side portion. In short, it is sufficient that the sub-bead 55 is formed at a portion corresponding to the boundary portion between the mating surface of the cylinder body 22 and the cylinder head 23 and the cooling water passages 26 and 36.

  In the embodiment described above, the outboard motor 10 is provided with a seal structure using a metal gasket. However, the seal structure using the metal gasket may be used for a boat such as a small planing boat provided with an engine in the hull. it can. Further, the arrangement, structure, material and the like of each part constituting the seal structure by the metal gasket according to the present invention can be appropriately changed within the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Outboard motor, 16 ... Engine, 22 ... Cylinder body, 23 ... Cylinder head, 24 ... Cylinder, 26, 28, 36, 37, 38 ... Cooling water flow path, 40, 60, 70 ... Metal gasket, 41a, 41b , 41c ... bore hole, 43a, 43b, 43c, 43d, 43e, 43f, 44a, 44b, 44c, 45a ... cooling water hole, 51, 52, 71, 72 ... bead plate, 53 ... shim member, 54, 74 ... primary bead, 55, 75 ... secondary bead, 61, 62, 63, 64 ... gap filler layer, 73 ... plate inner.

Claims (6)

The metal gasket is disposed on the mating surface of the cylinder head and the cylinder body in the engine body including a plurality of cylinder forming recesses and a coolant passage formed so as to surround the plurality of cylinder forming recesses. A seal structure with a metal gasket that seals the surface,
Forming a main bead that protrudes toward the mating surface at a portion corresponding to a substantially center between the cylinder forming recess and the cooling water flow path in the metal gasket;
Edges of the cooling water channel and the mating surfaces on both sides of the gasket so that a peak of surface pressure appears along portions corresponding to both side edges of the boundary between the mating surface of the engine body and the cooling water channel in the gasket. A metal gasket seal characterized in that it forms a trapezoidal sub-bead having a bent portion protruding toward the portion side portion to prevent intrusion of the cooling water in the cooling water passage between the mating surfaces. Construction.   The sealing structure by the metal gasket of Claim 1 which comprised the said metal gasket with the base material which consists of thin plate-shaped stainless steel.   The base material is composed of two stacked bead plates, and an inner member disposed at least in a portion forming the main bead between the two bead plates, the two bead plates and the The main bead is formed by forming a space portion between each of the inner members and a space portion at a predetermined portion between each of the two bead plates and the inner member or between the two bead plates. The seal structure by the metal gasket according to claim 2, wherein the sub-bead is formed by forming the sub-bead.   4. The sealing structure using a metal gasket according to claim 2, wherein a coating layer made of rubber is formed on the surface of the base material.   The metal gasket-sealed structure according to any one of claims 1 to 4, wherein a gap filler is applied to at least a portion of the surface of the metal gasket where the secondary bead is formed.   The outboard motor equipped with the metal gasket seal structure according to any one of claims 1 to 4, wherein the engine main body is an engine main body included in the outboard motor.

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