JP2008014263A - Cooling structure for internal combustion engine and cylinder head gasket used for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure for an internal combustion engine capable of especially effectively cooling a part near a cylinder head lower surface in cooling structures of open deck type water jackets and a cylinder head gasket used for the cooling structure. <P>SOLUTION: In the cooling structure for the internal combustion engine, a hollow part 22 is formed on a lower surface of a cylinder head 2 near a Siamese part, and a cooling water channel 4 isolated from the water jacket 12 is formed between the hollow part 22 and the cylinder head gasket 3. Openings 32, 34 corresponding to a part near the Siamese part and a downstream side end of the hollow part 22 are formed on the cylinder head gasket 3, cooling water C flowing vertically upward on the Siamese part of the water jacket 12 in the cylinder block 1 is introduced to the cooling water channel 4 from the upstream side opening 32, and cooling water D, E can be made flow under a rectified condition where flow speed is high by returning from the downstream side opening 34 to the water jacket 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure for cooling an internal combustion engine such as an automobile engine with cooling water and a cylinder head gasket used for obtaining the structure. In particular, the present invention relates to measures for efficiently cooling an internal combustion engine.

  Conventionally, as a cooling structure of an internal combustion engine (engine) applied for automobiles and the like, a water jacket (cooling water passage) is formed inside each of the cylinder block and the cylinder head, and between the cylinder block and the cylinder head. A structure (a cooling structure using a so-called open deck type water jacket) in which an opening (water hole) for communicating each water jacket is formed in a cylinder head gasket interposed in the cylinder is known (for example, the following patent document) 1). That is, the cooling water discharged from the water pump and flowing into the water jacket in the cylinder block is caused to flow into the water jacket in the cylinder head through the opening of the cylinder head gasket, whereby the cylinder block and the cylinder head are respectively cooled by the cooling water. I'm trying to cool it down.

  In addition, in the case of cylinder blocks and cylinder heads made of aluminum alloy, which have become widespread in recent years, when the temperature exceeds 200 ° C., the material strength cannot be obtained sufficiently, or thermal distortion occurs due to the temperature difference from the surroundings. There is a concern that In particular, when thermal distortion occurs around the lower surface of the cylinder head (the surface facing the fuel chamber) that tends to be high in the cylinder head, the sealing performance with the cylinder block may be deteriorated.

  Such a problem is particularly a concern in the so-called “siamese structure” in which the outer peripheral walls of cylinder bores adjacent to each other in the cylinder block are coupled. The cylinder block having this siamese structure is, for example, as disclosed in Patent Document 2 below, by combining the outer peripheral walls of cylinder bores adjacent to each other, thereby reducing the size and weight of the engine and the overall length (length in the cylinder row direction). Is intended to be shortened.

The cylinder block having this siamese structure has a short dimension between the cylinder bores (the area where adjacent cylinder bores are closest to each other, hereinafter referred to as “siamese part”). There is no passage. For this reason, the temperature rise in this siamese part is a concern. In particular, since the lower surface of the cylinder head directly receives heat from the combustion chamber, the temperature near the lower surface of the cylinder head in the vicinity of the siamese portion is considerably high, and the temperature near the lower surface of the cylinder head exceeds 200 ° C. There is a possibility that. For this reason, in designing the engine, it is necessary to sufficiently consider the cooling performance in the vicinity of the lower surface of the cylinder head to prevent the above-described reduction in material strength and thermal distortion.
JP 11-166450 A Japanese Patent Laid-Open No. 11-336606

  However, until now, no effective proposal has been made for cooling the vicinity of the lower surface of the cylinder head particularly effectively. Therefore, the inventor of the present invention has studied a configuration capable of particularly effectively cooling the vicinity of the lower surface of the cylinder head. In order to increase the cooling efficiency of this portion, it is effective to bring the cooling water into direct contact with the lower surface of the cylinder head and to allow the cooling water to flow in a rectified state and at a certain flow rate or higher. I focused on that.

  FIG. 13 is a cross-sectional view showing an example of a conventional structure in a communication portion between the water jacket a1 in the cylinder block a and the water jacket b1 in the cylinder head b (for example, a cross-sectional view around the water jacket along the outer peripheral surface of the cylinder bore). The flow of cooling water is indicated by arrows. As shown in this figure, conventionally, the water jacket a1 in the cylinder block a is opened on the upper surface of the cylinder block a and the water jacket b1 in the cylinder head b is opened on the lower surface of the cylinder head b. An opening c1 formed in the head gasket c is configured to communicate these open portions. In this case, the opening area of the opening c1 of the cylinder head gasket c is set to be smaller than the opening area of the open portions of the water jackets a1 and b1 in the cylinder block a and the cylinder head b, and the water jacket a1 in the cylinder block a is set. The amount of cooling water flowing into the water jacket b1 in the cylinder head b is adjusted (restricted).

  In such a configuration, since the lower surface of the cylinder head b is covered with the cylinder head gasket c, it is impossible to effectively cool the vicinity of the lower surface of the cylinder head b.

  FIG. 14 is a cross-sectional view (for example, a cross-sectional view of the same portion as in FIG. 13) showing another example of a conventional structure in a communication portion between the water jacket a1 in the cylinder block a and the water jacket b1 in the cylinder head b. The flow of cooling water is indicated by arrows. In the conventional example shown in FIG. 14, a recessed portion b2 is formed on the lower surface of the cylinder head b, and a flow path b3 for communicating the recessed portion b2 and the water jacket b1 in the cylinder head b is formed. The cooling water that has flowed from the water jacket a1 of the cylinder block a1 into the recess b2 through the openings c1 and c1 of the cylinder head gasket c is caused to flow into the water jacket b1 in the cylinder head b through the flow path b3. ing.

  In this case, since the intake port and the exhaust port are formed in the cylinder head b and various parts constituting the valve mechanism are accommodated, it is possible to ensure a large diameter dimension of the flow path b3. For example, the inner diameter is set to about 5 mm. In this case, the amount of cooling water passing through the flow path b3 per unit time is small, and as a result, the flow rate of the cooling water in the recessed portion b2 becomes very low, and the lower surface of the cylinder head b It was impossible to obtain a flow rate sufficient to cool the water.

  The above-described problem is not limited to the engine having the cylinder block having the siamese structure, but an engine having a cylinder block having a non-siamese structure (for example, a V-type six-cylinder engine has a cylinder block having a non-siamese structure. This is also the case.

  The present invention has been made in view of such a point, and an object of the present invention is to cool an internal combustion engine that can particularly effectively cool the vicinity of the lower surface of the cylinder head as compared with a cooling structure using a so-called open deck type water jacket. The object is to provide a cylinder head gasket for use in the structure and its cooling structure.

-Solving principle-
The solution principle of the present invention taken to achieve the above object is that the cooling water (for example, turbulence) flows between the lower surface of the cylinder head and the cylinder head gasket and has a relatively high flow rate and flows through the water jacket in the cylinder block. By generating a cooling water flow separated from the cooling water in a flow state, the vicinity of the lower surface of the cylinder head can be cooled particularly effectively.

-Solution-
Specifically, the present invention provides a cooling structure for an internal combustion engine configured as an open deck type in which a cooling water passage in a cylinder block and a cooling water passage in a cylinder head communicate with each other through an opening formed in a cylinder head gasket. Assumption. With respect to the cooling structure of the internal combustion engine, a cylinder head coolant passage extending in the extending direction of the facing surface is formed between the facing surface facing the cylinder block and the cylinder head gasket in the cylinder head. The cylinder head gasket is formed with a cooling water introduction opening located on one end side in the extending direction of the cylinder head cooling water passage and a cooling water outlet opening located on the other end side, respectively. Thus, the cooling water flow from the cooling water introduction opening toward the cooling water outlet opening is generated.

  Due to this specific matter, the cylinder head cooling water passage is largely separated from the cooling water passage in the cylinder block by the cylinder head gasket, that is, the cylinder head facing surface (the surface facing the cylinder block). It will be obtained as a dedicated passage for cooling. For this reason, it is a rectified state that is less affected by the cooling water flow (turbulent flow) in the cooling water passage in the cylinder block, and has a relatively high flow rate from the cooling water introduction opening to the cooling water outlet opening. It becomes possible to flow water through the cooling water passage for the cylinder head. As a result, the opposing surface of the cylinder head can be effectively cooled.

  Specific examples of the configuration of the cylinder block and the formation position of the cooling water introduction opening of the cylinder head gasket suitable for the cylinder block include the following configurations. First, the cylinder block is configured in a siamese structure. Then, the cooling water introduction opening of the cylinder head gasket is formed in the vicinity of the siamese portion, which is a boundary portion between adjacent cylinder bores, and flows from the cooling water passage in the cylinder block toward the cylinder head in the vicinity of the siamese portion. The cooling water (for example, cooling water flowing vertically upward near the siamese portion) is guided to the cylinder head cooling water passage.

  This makes it possible to sufficiently cool the siamese portion between the cylinders, which are particularly likely to be at high temperatures, and to effectively cool both the opposed surface of the cylinder head and the siamese portion between the cylinders. It becomes possible.

  Specific configurations in the case where the cylinder head cooling water passage is formed between the plate members constituting the cylinder head gasket in the laminated structure of the cylinder head gasket include the following. In other words, the cylinder head gasket is formed by laminating a plurality of plate materials, and the plate material positioned on the cylinder block side is curved so as to recede from the plate material positioned on the cylinder head side, thereby cooling the cylinder head. Form a water passage. Further, an opening for exposing the mating surface of the cylinder head to the cylinder head coolant passage is formed in a region facing the curved portion of the plate member located on the cylinder block side among the plate members located on the cylinder head side. The cooling water flowing through the cooling water passage is brought into direct contact with the exposed mating surface.

  As a result, the cylinder head cooling water passage is formed by using the respective plates constituting the cylinder head gasket, and the mating surface of the cylinder head is directly adjusted by the cooling water flowing through the cylinder head cooling water passage. It can cool and can obtain high cooling efficiency.

  Specific examples of the shape applied to the edge of the cooling water outlet opening in the cylinder head gasket include the following. That is, the cooling water in the cylinder block is joined to the cooling water flowing in the cooling water passage in the cylinder block and the cooling water led out to the cooling water passage in the cylinder block from the cooling water outlet opening at the edge. A cooling water guide portion is formed to deflect the flow line direction of the cooling water flowing through the passage in a direction away from the cooling water outlet opening.

  According to this, in the cooling water merging portion, the cooling water flowing through the cooling water passage in the cylinder block is deflected away from the cooling water outlet opening. The cooling water led out to the cooling water passage in the cylinder block is smoothly flowed into the cooling water passage in the cylinder block without receiving almost any resistance due to the cooling water flowing through the cooling water passage in the cylinder block. become. For this reason, it is possible to prevent a decrease in the flow rate of the cooling water in the cylinder head cooling water passage, and it is also possible to obtain a high cooling effect by the cooling water flowing in the cylinder head cooling water passage.

  In addition, as the cross-sectional area of the cross section approximately perpendicular to the coolant flow direction inside the passage on the inner surface of the cylinder head cooling water passage, the cross sectional area on the cooling water outlet opening side is larger than the cross sectional area on the cooling water introduction opening side It is possible to provide a stepped portion. According to this configuration, the flow passage cross-sectional area of the cylinder head cooling water passage is enlarged at the step portion, and accordingly, the water pressure on the cooling water outlet opening side is lowered. For this reason, the flow rate of the cooling water in the cooling water passage for the cylinder head can be increased by the pressure difference between the cooling water introduction opening side (high pressure side) and the cooling water outlet opening side (low pressure side). Can get higher.

  Furthermore, the cylinder head gasket used in the cooling structure of any one of the above-described solutions is also within the scope of the technical idea of the present invention. That is, in the cylinder head cooling water passage, the cooling water introduction opening located on one end side in the extension direction of the cylinder head cooling water passage so that a cooling water flow along the extension direction of the facing surface is generated, and This is a cylinder head gasket in which a cooling water outlet opening located on the other end side is formed.

  In the present invention, the coolant flow passage for the cylinder head is formed between the lower surface of the cylinder head and the cylinder head gasket, and the coolant introduction opening and the coolant discharge opening are respectively formed in the cylinder head gasket. The cooling water flow is high and is separated from the cooling water flowing through the water jacket in the cylinder block. Thereby, it becomes possible to effectively cool the vicinity of the facing surface (for example, the lower surface of the cylinder head) facing the cylinder block in the cylinder head.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a case will be described in which the present invention is applied to an in-line four-cylinder gasoline engine for automobiles equipped with a cylinder block having a siamese structure.

  In the following embodiments, the cylinder blocks have the same configuration, and the shapes of the coolant passages formed by the cylinder head and the cylinder head gasket are different from each other. For this reason, in the following description, after first describing the configuration of the cylinder block common to each embodiment, the configuration of the cylinder head and the cylinder head gasket and the shape of the cooling water passage in each embodiment will be described.

−Cylinder block configuration−
FIG. 1 is a plan view of a cylinder block 1 showing each cylinder bore 11, 11,... Of the in-line four-cylinder gasoline engine according to the present embodiment and its peripheral portion, and a cylinder head 2 (see FIG. 2) to be described later. The arrangement state of the mating surface, the cylinder row, and the water jacket (cooling water passage) 12 is shown. In the following description, the leftmost cylinder in FIG. 1 is the first cylinder # 1, the right cylinder is the second cylinder # 2, and the right cylinder is the third cylinder. The cylinder located at # 3 and the right end will be described as the fourth cylinder # 4. Moreover, the upper side in FIG. 1 is described as the intake side, and the lower side is described as the exhaust side. The form of the cylinder number and the intake / exhaust system is not limited to this.

  The cylinder block 1 that is a constituent member of the in-line four-cylinder engine according to the present embodiment is made of an aluminum alloy, and as shown in FIG. 1, four cylinder barrels 13a, 13a,. A siamese cylinder barrel 13 formed integrally is provided. And the cylinder liner which forms the inner surface of cylinder bore 11,11, ... is cast in the inner surface of each cylinder barrel 13a, 13a, ..., respectively.

  The cylinder block 1 is configured as an open deck type. That is, the water jacket 12 is opened on the top surface of the cylinder block 1 that is the assembly surface of the cylinder head 2. The water jacket 12 is formed between the outer wall of the cylinder block 1 and the siamese cylinder barrel 13 so as to surround substantially the entire circumference of the siamese cylinder barrel 13. Therefore, as shown in FIG. 1, the water jacket 12 includes a main jacket region A extending along a cylindrical surface shape that is an outer peripheral surface of each cylinder barrel 13a, 13a,... And a cylinder barrel 13a, 13a,. It has a configuration including a siamese jacket region B formed as a constricted portion (region formed by a substantially V-shaped concave portion in a plan view) recessed toward each other (siamese portion 15).

  Further, the cylinder block 1 has a cooling water inlet passage 12a for introducing cooling water from the water pump into the water jacket 12 at one end side (left end side in FIG. 1) in the cylinder row direction, that is, the first cylinder # 1 is formed in the vicinity.

  The main flow of the cooling water in the water jacket 12 of the cylinder block 1 is that the cooling water introduced from the cooling water inlet passage 12a is substantially horizontal along the arrangement direction of the cylinder barrels 13a, 13a,. Thus, the cylinder block 1 is cooled. Specifically, the cooling water flowing in from the cooling water inlet passage 12a is divided into one side (the intake side which is the upper side in FIG. 1) and the other side (the exhaust side which is the lower side in FIG. 1) of the siamese cylinder barrel 13. Thus, each flows in a substantially horizontal direction from the first cylinder # 1 to the fourth cylinder # 4 (see the arrow in FIG. 1), whereby the cylinder block 1 is cooled. The cooling water flows into the water jacket 25 of the cylinder head 2 through passages such as an opening 32 formed in a cylinder head gasket 3 to be described later and a communication passage 22c (see FIG. 4) formed in the cylinder head 2. Then, after cooling the cylinder head 2 or cooling auxiliary parts, etc., the cylinder head 2 is returned to the water pump.

  It should be noted that head bolt holes 16, 16,... Through which head bolts for assembling the cylinder head gasket 3 and the cylinder head 2 integrally are formed are formed at a plurality of locations on the cylinder block 1.

  Next, the configuration of the cylinder head 2 assembled integrally with the cylinder block 1 configured as described above, the configuration of the cylinder head gasket 3 interposed between the cylinder block 1 and the cylinder head 2, A plurality of embodiments of the shape of the cylinder head cooling water passage 4 (hereinafter simply referred to as a cooling water passage) formed by being assembled integrally will be described.

(First embodiment)
First, the first embodiment will be described.

-Configuration of cylinder head 2-
FIG. 2 is a view showing the lower surface of the cylinder head 2 (opposite surface facing the cylinder block 1) in the present embodiment, and the concave surfaces 21 and 21 for constituting the mating surface with the cylinder block 1 and the combustion chamber. ,... Are shown (the intake and exhaust ports are not shown). The cylinder head 2 is overlapped on the upper surface of the cylinder block 1 with the front side in FIG. 2 facing downward (reversed), so the lower side in FIG. 2 is the intake side and the upper side is the exhaust side. It has become.

  The cylinder head 2 is also made of an aluminum alloy, and has a water jacket 25 (see FIG. 4) formed therein, and a concave portion for forming the cooling water passage 4 characterized by the present embodiment on the lower surface. Are formed at a plurality of locations. .. Are formed in a part of a position corresponding to the open portion of the water jacket 12 in the cylinder block 1, and a part of the cooling water flowing through the water jacket 12 of the cylinder block 1. And the cooling water which passed the opening 32 currently formed in the cylinder head gasket 3 mentioned later flows in. Hereinafter, the shape of each recessed part 22, 22, ... will be described.

  These concave portions 22, 22,... Are a total of eight concave portions 22, which are formed on the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4, respectively, and have the same shape or symmetrical shapes. 22...

  Here, in particular, a description will be given on behalf of the recessed portion 22 formed on the exhaust side of the second cylinder # 2.

  As shown in FIG. 2, the recess 22 extends from the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 to the main jacket region A on the outer peripheral side of the second cylinder # 2. It is formed in a substantially arc shape in plan view (a shape corresponding to the open portion of the water jacket 12). The Siamese jacket region B and its peripheral part are formed as a first concave part 22a having a comparatively small concave dimension (for example, a depth of about 5 mm), on the other hand, on the downstream side of the first concave part 22a (third The numbered cylinder # 3 side) is formed as a second recessed portion 22b having a recessed dimension larger than that of the first recessed portion 22a (for example, a depth of about 20 mm). A communication passage 22c is formed at a substantially central position in the longitudinal direction of the second recessed portion 22b to communicate the water jacket 25 formed inside the cylinder head 2 with the second recessed portion 22b. . The inner diameter of the communication path 22c is set to be relatively small (for example, about 5 mm). The reason for this is that an intake port and an exhaust port are formed inside the cylinder head 2 and a housing space for various components constituting the valve operating mechanism is formed, so that the diameter of the communication passage 22c is ensured to be large. Because it is difficult. Therefore, the cooling water that has flowed into the recessed portion 22 from the water jacket 12 of the cylinder block 1 flows into the second recessed portion 22b through the first recessed portion 22a (see arrow D in FIG. 2), and a part of the cooling water continues. It passes through the passage 22c and flows into the water jacket 25 inside the cylinder head 2 to cool the cylinder head 2 (details of the flow of cooling water will be described later). The concave portions 22 configured as described above are formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (the right side in FIG. 2) of the fourth cylinder # 4, an introduction opening 23 for introducing cooling water from the water jacket 12 inside the cylinder block 1 into the water jacket 25 inside the cylinder head 2. , 23 are formed in two places.

  The same head bolt holes 24, 24,... Are formed at positions corresponding to the head bolt holes 16, 16,.

-Configuration of cylinder head gasket 3-
FIG. 3 is a plan view showing the cylinder head gasket 3 in the present embodiment. As shown in FIG. 3, the cylinder head gasket 3 has an outer edge shape similar to the outer edge shape on the upper surface of the cylinder block 1. For example, two plate members made of stainless steel are integrally laminated. Yes. In the cylinder head gasket 3, bore openings 31, 31,... Are formed at positions corresponding to the cylinder bores 11, 11,. A shim is interposed between the two plate members constituting the cylinder head gasket 3 at the edge of the bore openings 31, 31,... In order to improve the sealing performance, the gasket surface pressure at the cylinder bore is increased.

  The cylinder head gasket 3 has a plurality of openings 32, 33, 34 corresponding to a part of the formation position of the water jacket 12 formed in the cylinder block 1. The cooling water passage 4 is formed by 33 and 34 and the respective recessed portions 22 of the cylinder head 2 described above.

  Hereinafter, the openings 32 to 34 will be described. Since the opening positions of the openings 32, 33, 34 formed on the intake side and the exhaust side around the first cylinder # 1 to the fourth cylinder # 4 in the cylinder head gasket 3 are the same, In particular, the openings 32, 33, and 34 formed on the exhaust side of the second cylinder # 2 will be described as a representative.

  As shown in FIG. 3, these openings 32, 33, 34 are formed as a set on the exhaust side of the second cylinder # 2. Specifically, a first opening (cooling water introduction opening) 32 formed corresponding to the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2, and the first opening 32 The second opening 33 formed on the downstream side (third cylinder # 3 side) and the third opening (third cylinder # 3 side) formed further downstream (second cylinder # 3 side) than the second opening 33. Cooling water outlet opening) 34 is formed. The second opening 33 is formed so as to correspond to the upstream end of the second recessed portion 22b formed on the lower surface of the cylinder head 2 (the boundary portion with the first recessed portion 22a). The third opening 34 is formed to correspond to a downstream end (end on the third cylinder # 3 side) of the second recessed portion 22b formed on the lower surface of the cylinder head 2. Note that the length dimensions (length dimensions in the direction along the horizontal flow of the cooling water) in the second opening 33 and the third opening 34 are set to be substantially the same. In this way, on the exhaust side of the second cylinder # 2, the water jacket 12 of the cylinder block 1 and the recessed portion 22 of the cylinder head 2 communicate with each other through three openings 32, 33, and 34. It has become. Each of the openings 32, 33, and 34 thus configured is formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (the right side in FIG. 3) of the fourth cylinder # 4, communication holes 35, 35 are formed corresponding to the positions where the introduction openings 23, 23 formed in the cylinder head 2 are formed. Yes. As a result, the coolant that has reached the rear side of the fourth cylinder # 4 in the water jacket 12 inside the cylinder block 1 passes through the communication holes 35 and 35 and the introduction openings 23 and 23 formed in the cylinder head 2. Then, it is introduced into the water jacket 25.

  It should be noted that the same head bolt holes 36, 36,... Are formed at positions corresponding to the head bolt holes 16, 16,.

-Explanation of cooling water passage 4 and cooling water flow-
Next, the cooling water passage 4 formed by integrally assembling the cylinder head 2 and the cylinder head gasket 3 configured as described above to the cylinder block 1 and the cooling water flow in the cooling water passage 4 will be described. In addition, since this embodiment has the most characteristic in the cooling water flow in the said Siamese jacket area | region B and its peripheral part, the cooling water flow in this part is mainly demonstrated.

  4 is a cross-sectional view at a position corresponding to line IV-IV in FIG. 1 in a state where the cylinder block 1, the cylinder head gasket 3, and the cylinder head 2 are integrally assembled by a head bolt.

  As shown in FIG. 4, when the cylinder block 1, the cylinder head gasket 3, and the cylinder head 2 are assembled together, the water jacket 12 of the cylinder block 1 and the recesses formed on the lower surface of the cylinder head 2. The portion 22 is isolated by the cylinder head gasket 3 and partially communicated (at positions where the openings 32, 33, 34 are formed in the cylinder head gasket 3).

  Specifically, in the Siamese jacket region B, the water jacket 12 of the cylinder block 1 is in a state of communicating in the vertical direction with the first recessed portion 22 a of the cylinder head 2 through the first opening 32 of the cylinder head gasket 3. .

  Further, in the upstream portion of the main jacket region A close to the siamese jacket region B, the water jacket 12 of the cylinder block 1 is formed in the second recessed portion 22 b of the cylinder head 2 by the second opening 33 of the cylinder head gasket 3. It is in a state of communicating in the vertical direction.

  Further, in the downstream portion of the main jacket region A away from the siamese jacket region B, the water jacket 12 of the cylinder block 1 is connected to the second recessed portion 22b of the cylinder head 2 by the third opening 34 of the cylinder head gasket 3. It is in the state where it communicated in the vertical direction.

  As the cooling water flow in the cooling water passage 4 formed in this way, the cooling water introduced from the cooling water inlet passage 12a first moves the water jacket 12 of the cylinder block 1 in the horizontal direction as the water pump is driven. Flowing into. That is, the first cylinder # 1 is cooled by flowing in the main jacket region A around the first cylinder # 1 in the horizontal direction.

  Then, after cooling the first cylinder # 1, a part of the cooling water flowing into the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 remains as it is in the cylinder block 1. By flowing in the water jacket 12 in the horizontal direction and flowing in the main jacket region A around the second cylinder # 2, it contributes to cooling of the second cylinder # 2. The other coolant flows vertically upward in the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2, passes through the first opening 32 of the cylinder head gasket 3, and the cylinder head 2 Into the first recess 22a (see arrow C in FIG. 4). The cooling water that has flowed into the first recess 22a changes the streamline direction to the horizontal direction, and flows from the first recess 22a into the second recess 22b (see arrow D in FIG. 4). By this flow, the inner wall surfaces of the first concave portion 22a and the second concave portion 22b, that is, the lower surface of the cylinder head 2 are directly cooled by the cooling water.

  Then, most of the cooling water flowing through the second recessed portion 22b reaches the downstream end of the second recessed portion 22b, and the streamline direction is changed downward to open the third opening 34 of the cylinder head gasket 3. It passes and flows again into the water jacket 12 of the cylinder block 1 (see arrow E in FIG. 4). As a result, the cooling water (see arrow F in FIG. 4) flowing through the main jacket region A around the second cylinder # 2 joins, and between the second cylinder # 2 and the third cylinder # 3. Will flow toward the Siamese jacket region B. Thus, in the cooling water passage 4 formed between the recess 22 and the cylinder head gasket 3, the first opening 32 serves as an inflow port and the third opening 34 serves as an outflow port. The cooling water flows at a relatively high flow rate without staying, and the lower surface of the cylinder head 2 (the inner surface of the recessed portion 22) is efficiently cooled.

  The water jacket 12 and the second recessed portion 22b of the cylinder block 1 communicate with each other through the second opening 33 of the cylinder head gasket 3. In the second opening 33, a part of the cooling water passes from the water jacket 12 and the second recessed portion 22 b toward the low water pressure side from the high water pressure side. Specifically, in a situation where the water pressure in the water jacket 12 is higher than the water pressure in the second recessed portion 22b, a part of the cooling water flowing in the water jacket 12 passes through the second opening 33 and enters the second recessed portion. It flows into the portion 22b. Thereby, the flow volume of the cooling water in the 2nd recessed part 22b is raised.

  Further, since the boundary portion between the first recessed portion 22a and the second recessed portion 22b is formed as a stepped portion 4A that enlarges the passage cross-sectional area, the flow passage cross-sectional area of the cooling water passage 4 in the stepped portion 4A. Is expanded, and accordingly, the water pressure on the third opening 34 side (cooling water outlet opening side) becomes lower. For this reason, in this cooling water passage 4, the flow rate of the cooling water in the cooling water passage 4 is reduced by the pressure difference between the first concave portion 22a side (high pressure side) and the second concave portion 22b side (low pressure side). It is possible to increase the cooling effect.

  Further, a part of the cooling water flowing through the second recessed portion 22b passes through the communication passage 22c formed in the cylinder head 2 and flows into the water jacket 25 of the cylinder head 2 to cool the cylinder head 2 ( (See arrow G in FIG. 4).

  After flowing through the main jacket region A around the second cylinder # 2, the flow of the cooling water flowing into the siamese jacket region B between the second cylinder # 2 and the third cylinder # 3 is also possible. This is the same as described above. That is, the flow contributing to the cooling of the third cylinder # 3 by flowing in the water jacket 12 of the cylinder block 1 in the horizontal direction and flowing in the main jacket area A around the third cylinder # 3, and the siamese jacket area B flows vertically upward, flows into the recessed portion 22 around the third cylinder # 3, and is divided into a flow for cooling the lower surface of the cylinder head 2 (the inner surface of the recessed portion 22). Similarly to the above-described case, the cooling water diverted into the recessed portion 22 passes through the third opening 34 of the cylinder head gasket 3 and flows through the main jacket region A around the third cylinder # 3. The water merges and flows toward the siamese jacket region B between the third cylinder # 3 and the fourth cylinder # 4. Further, the flow of the cooling water flowing into the siamese jacket region B between the third cylinder # 3 and the fourth cylinder # 4 is the same as that described above.

  Then, the cooling water that has cooled the fourth cylinder # 4 passes through the communication holes 35 and 35 formed in the cylinder head gasket 3 and the introduction openings 23 and 23 formed in the cylinder head 2, and this cylinder head 2 It will be introduced into the internal water jacket 25. The cooling water that has flowed into the water jacket 25 inside the cylinder head 2 is taken out of the cylinder head 2 and recovered toward the radiator after the cylinder head 2 is cooled.

  Since the same cooling water passage 4 is formed around the first cylinder # 1 as described above, a part of the cooling water introduced from the cooling water inlet passage 12a is the same as in the above case. In addition, the introduction into the cooling water passage 4 contributes to the cooling of the lower surface of the cylinder head 2.

  As described above, in this embodiment, the space between the water jacket 12 of the cylinder block 1 and the recessed portion 22 formed on the lower surface of the cylinder head 2 is isolated by the cylinder head gasket 3 and partially (cylinder The head gasket 3 is configured to communicate with each other (at positions where the openings 32 to 34 are formed). For this reason, the cooling water passage 4 formed between the cylinder head 2 and the cylinder head gasket 3 is obtained as a dedicated passage for cooling the lower surface of the cylinder head 2, and the cooling water in the water jacket 12 is obtained. The rectification state is less affected by the flow (turbulent flow). In the cooling water passage 4, the flow rate is relatively high from the first opening 32 of the cylinder head gasket 3 serving as the upstream opening toward the third opening 34 of the cylinder head gasket 3 serving as the downstream opening. Cooling water is flowing. For this reason, the lower surface of the cylinder head 2 can be effectively cooled. In particular, in the present embodiment, since the cooling water is caused to flow in the vertical direction in the siamese jacket region B, it is possible to sufficiently cool the siamese portion 15 between the cylinders, which are particularly likely to reach a high temperature. As a result, according to the cooling structure of the present embodiment, it is possible to effectively perform both cooling of the lower surface of the cylinder head 2 and cooling of the siamese portion 15 between the cylinders.

(Second Embodiment)
Next, a second embodiment will be described. Since the configuration of the cylinder block 1 has been described above, only the configuration of the cylinder head 2 and the cylinder head gasket 3 and the shape of the cooling water passage 4 will be described here.

-Configuration of cylinder head 2-
FIG. 5 is a view corresponding to FIG. 2 in the present embodiment (a view showing the lower surface of the cylinder head 2).

  The cylinder head 2 is also made of an aluminum alloy, and has a water jacket 25 (see FIG. 8) formed therein, and a concave portion for forming a cooling water passage 4 characterized by the present embodiment on the lower surface. Are formed at a plurality of locations. Even in the recesses 22, 22,... In the present embodiment, they are formed in a part of the cylinder block 1 corresponding to the open portion of the water jacket 12, and flow through the water jacket 12 of the cylinder block 1. The cooling water that is a part of the cooling water that has passed through openings 32A and 32B formed in the cylinder head gasket 3 to be described later flows. Hereinafter, each recessed part 22,22, ... is demonstrated.

  .. Are formed in a total of eight locations on the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4. In particular, here, the second cylinder # 1 is used. 2 will be described as a representative of the recessed portion 22 formed on the exhaust side.

  As shown in FIG. 5, the recess 22 extends from the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 to the main jacket region A on the outer peripheral side of the second cylinder # 2. It is formed over. The Siamese jacket region B and its peripheral portion are formed as first concave portions 22a having a relatively small concave size (for example, a depth of about 5 mm). Further, the downstream side (the third cylinder # 3 side) of the first concave part 22a is formed as a second concave part 22b having a concave dimension larger than that of the first concave part 22a (for example, a depth of about 20 mm). Yes. In the present embodiment, the first concave portion 22a and the second concave portion 22b are different from those in the first embodiment in that they are not continuous concave portions. That is, a recessed portion partition wall 22d that is not recessed (coplanar with the lower surface of the cylinder head 2) is formed between the first recessed portion 22a and the second recessed portion 22b.

  A communication passage 22c is formed at a substantially central position in the longitudinal direction of the second recess 22b to communicate the water jacket 25 formed inside the cylinder head 2 with the second recess 22b. . The inner diameter of the communication path 22c is set to be relatively small (for example, about 5 mm). For this reason, a part of the cooling water (see arrow D in FIG. 5) that flows into the second recessed portion 22 b passes through the communication path 22 c and flows into the water jacket 25 inside the cylinder head 2 to cool the cylinder head 2. It is configured as follows. The concave portions 22 configured as described above are formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  In addition, on the rear side (the right side in FIG. 5) of the fourth cylinder # 4, introduction openings 23, 23 similar to those in the first embodiment are formed in two places.

  The same head bolt holes 24, 24,... Are formed at positions corresponding to the head bolt holes 16, 16,.

-Configuration of cylinder head gasket 3-
The cylinder head gasket 3 in the present embodiment is different from each other in the formation positions of the openings 32A to 34A and 32B to 34B in two plate members (hereinafter referred to as gasket plates 3A and 3B) constituting the cylinder head gasket 3. Yes. FIG. 6 is a plan view of the upper (cylinder head 2 side) upper gasket plate 3A, and FIG. 7 is a plan view of the lower (cylinder block 1 side) lower gasket plate 3B. Hereinafter, each gasket plate 3A, 3B is demonstrated.

  As shown in FIG. 6, the upper gasket plate 3 </ b> A has a plurality of openings 32 </ b> A, 33 </ b> A, 34 </ b> A corresponding to a part of the formation position of the water jacket 12 formed in the cylinder block 1. The cooling water passage 4 is formed by the openings 32A, 33A, 34A and the concave portions 22 of the cylinder head 2 described above.

  Hereinafter, the openings 32A to 34A will be described. Since the opening positions of the openings 32A, 33A, and 34A formed on the intake side and the exhaust side around the first cylinder # 1 to the fourth cylinder # 4 in the upper gasket plate 3A are the same, here, In particular, the openings 32A, 33A, 34A formed on the exhaust side of the second cylinder # 2 will be described as a representative.

  As shown in FIG. 6, these three openings 32A, 33A, and 34A are formed as a set on the exhaust side of the second cylinder # 2. Specifically, the first opening 32A formed corresponding to the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 and the downstream side (the first opening 32A). A second opening 33A formed on the third cylinder # 3 side) and a third opening 34A formed further downstream (the third cylinder # 3 side) than the second opening 33A are formed. .

  The first opening 32A and the third opening 34A are the same openings as the first opening 32 and the third opening 34 in the first embodiment, respectively. On the other hand, the second opening 33A corresponds to a region extending over part of the first recessed part 22a, the recessed part partition wall 22d, and the second recessed part 22b formed on the lower surface of the cylinder head 2. It is formed with a relatively long opening (long in the direction along the horizontal flow of the cooling water).

  Each of the openings 32A, 33A, and 34A configured in this way is formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (the right side in FIG. 6) of the fourth cylinder # 4, communication holes 35, 35 similar to the cylinder head gasket 3 in the first embodiment are formed.

  On the other hand, as shown in FIG. 7, the lower gasket plate 3B has a plurality of openings 32B, 33B, 34B corresponding to a part of the formation position of the water jacket 12 formed in the cylinder block 1. The cooling water passage 4 is formed by the openings 32B, 33B, and 34B and the concave portions 22 of the cylinder head 2 described above.

  Hereinafter, the openings 32B to 34B will be described. Since the positions of the openings 32B, 33B, and 34B formed on the intake side and the exhaust side around the first cylinder # 1 to the fourth cylinder # 4 in the lower gasket plate 3B are the same as each other, here too In particular, the openings 32B, 33B, and 34B formed on the exhaust side of the second cylinder # 2 will be described as a representative.

  As shown in FIG. 7, these openings 32B, 33B, and 34B are formed as a set on the exhaust side of the second cylinder # 2. Specifically, a first opening 32B formed corresponding to the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 and a downstream side (first number) from the first opening 32B. A second opening 33B formed on the third cylinder # 3 side) and a third opening 34B formed further downstream (the third cylinder # 3 side) than the second opening 33B are formed. .

  The first opening 32B and the third opening 34B are the same openings as the first opening 32 and the third opening 34 in the first embodiment, respectively. On the other hand, the second opening 33 </ b> B is formed at a position facing the second recessed portion 22 b formed on the lower surface of the cylinder head 2.

  As a feature of the lower gasket plate 3B, a region between the first opening 32B and the second opening 33B is formed as a curved portion 37 curved downward, and the cylinder head gasket 3 is connected to the cylinder block 1. In a state assembled with the cylinder head 2, the curved portion 37 retreats downward from the recessed portion partition wall 22d of the cylinder head 2 and forms a cooling water passage with the recessed portion partition wall 22d. (See FIG. 8). Further, the downstream end of the curved portion 37 is slightly curved upward (cylinder head 2 side), and guides the cooling water flowing through the cooling water passage obliquely upward (toward the cylinder head 2 side). It is like that.

  Each of the openings 32B, 33B, and 34B configured as described above is formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (right side in FIG. 7) of the fourth cylinder # 4, communication holes 35, 35 similar to the upper gasket plate 3A are formed.

  The same head bolt holes 36, 36,... Are formed at positions corresponding to the head bolt holes 16, 16,... Of the cylinder block 1 at a plurality of locations on the gasket plates 3A, 3B.

  As described above, the cylinder head gasket 3 is configured by integrally stacking the gasket plates 3A and 3B in which the openings 32A to 34A and 32B to 34B are formed.

-Explanation of cooling water passage 4 and cooling water flow-
Next, the cooling water passage 4 formed by integrally assembling the cylinder head 2 and the cylinder head gasket 3 configured as described above to the cylinder block 1 and the cooling water flow in the cooling water passage 4 will be described. Even in the present embodiment, the cooling water flow in the Siamese jacket region B and its peripheral part is the most characteristic. Therefore, the cooling water flow in this part will be mainly described.

  FIG. 8 is a cross-sectional view at a position corresponding to the line IV-IV in FIG. 1 in a state where the cylinder block 1, the cylinder head gasket 3, and the cylinder head 2 are integrally assembled by a head bolt.

  As shown in FIG. 8, when the cylinder block 1, the cylinder head gasket 3, and the cylinder head 2 are assembled together, the water jacket 12 of the cylinder block 1 and the recesses formed on the lower surface of the cylinder head 2. The portion 22 is isolated by the cylinder head gasket 3 and partially communicated (at positions where the openings 32A, 32B, 33A, 33B, 34A, 34B are formed in the cylinder head gasket 3).

  Specifically, in the Siamese jacket region B, the water jacket 12 of the cylinder block 1 communicates in the vertical direction with the first recessed portion 22a of the cylinder head 2 through the first openings 32A and 32B of the cylinder head gasket 3. ing.

  In the upstream portion of the main jacket region A close to the siamese jacket region B, the water jacket 12 of the cylinder block 1 is connected to the second recessed portion of the cylinder head 2 by the second openings 33A and 33B of the cylinder head gasket 3. 22b is in a state of communicating in the vertical direction.

  More specifically, as the shape of the cooling water passage in this portion, the second opening 33A formed in the upper gasket plate 3A as described above is a part of the first recess 22a formed in the lower surface of the cylinder head 2. The concave part partition wall 22d and the second concave part 22b are formed so as to correspond to the region. On the other hand, a curved portion 37 is formed in a region between the first opening 32B and the second opening 33B in the lower gasket plate 3B. For this reason, in a state where the cylinder head gasket 3 configured by superposing the upper gasket plate 3A and the lower gasket plate 3B is assembled between the cylinder block 1 and the cylinder head 2, the recessed portion of the cylinder head 2 is provided. The partition wall 22d is exposed in the second opening 33A of the upper gasket plate 3A, and the curved portion 37 of the lower gasket plate 3B recedes downward from the recessed portion partition wall 22d of the cylinder head 2, and this recessed portion partition A cooling water passage is formed with the wall 22d. That is, the cooling water passage formed between the recessed portion partition wall 22d and the curved portion 37 of the cylinder head 2 is configured to communicate the first recessed portion 22a and the second recessed portion 22b.

  Further, in the downstream portion of the main jacket region A away from the siamese jacket region B, the water jacket 12 of the cylinder block 1 is connected to the second recess 34 of the cylinder head 2 by the third openings 34A and 34B of the cylinder head gasket 3. It is in the state where it communicated with the portion 22b in the vertical direction.

  As the cooling water flow in the cooling water passage 4 formed in this way, the cooling water introduced from the cooling water inlet passage 12a first moves the water jacket 12 of the cylinder block 1 in the horizontal direction as the water pump is driven. Flowing into. That is, the first cylinder # 1 is cooled by flowing in the main jacket region A around the first cylinder # 1 in the horizontal direction.

  Then, after cooling the first cylinder # 1, a part of the cooling water flowing into the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 remains as it is in the cylinder block 1. By flowing in the water jacket 12 in the horizontal direction and flowing in the main jacket region A around the second cylinder # 2, it contributes to cooling of the second cylinder # 2. The other coolant flows vertically upward in the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2, and passes through the first openings 32A and 32B of the cylinder head gasket 3 to form a cylinder. It flows into the first recess 22a of the head 2 (see arrow C in FIG. 8). The cooling water that has flowed into the first recess 22a changes the streamline direction to the horizontal direction and flows from the first recess 22a toward the second recess 22b. At this time, it passes through the cooling water passage formed between the curved portion 37 of the lower gasket plate 3B and the recessed partition wall 22d of the cylinder head 2, and is then guided by the curved portion 37 to form the second recessed portion. It flows into the portion 22b (see arrow D in FIG. 8). By this flow, in addition to the inner wall surfaces of the first recessed portion 22a and the second recessed portion 22b, the lower surface of the recessed portion partition wall 22d is also directly cooled by the cooling water.

  And most of the cooling water flowing through the second recessed portion 22b reaches the downstream end of the second recessed portion 22b, and the streamline direction is changed downward so that the third openings 34A, It passes through 34B and flows again into the water jacket 12 of the cylinder block 1 (see arrow E in FIG. 8). As a result, the cooling water (see arrow F in FIG. 8) flowing through the main jacket region A around the second cylinder # 2 joins and is between the second cylinder # 2 and the third cylinder # 3. Will flow toward the Siamese jacket region B. As described above, also in the present embodiment, the first openings 32A and 32B are formed in the cooling water passage 4 formed between the recessed portion 22 and the cylinder head gasket 3 as in the case of the first embodiment described above. Since the third openings 34A and 34B serve as inflow ports and the outflow ports, the cooling water flows at a relatively high flow rate without the retention of the cooling water, and the lower surface of the cylinder head 2 is efficiently cooled. Become.

  The water jacket 12 and the second recessed portion 22b of the cylinder block 1 communicate with each other through the second openings 33A and 33B of the cylinder head gasket 3. The effect of forming the second openings 33A and 33B is the same as in the case of the first embodiment.

  Further, a part of the cooling water flowing through the second recessed portion 22b passes through the communication passage 22c formed in the cylinder head 2 and flows into the water jacket 25 of the cylinder head 2 to cool the cylinder head 2 ( (See arrow G in FIG. 8).

  After flowing through the main jacket region A around the second cylinder # 2, the flow of the cooling water flowing into the siamese jacket region B between the second cylinder # 2 and the third cylinder # 3 is also possible. This is the same as described above. That is, the flow contributing to the cooling of the third cylinder # 3 by flowing in the water jacket 12 of the cylinder block 1 in the horizontal direction and flowing in the main jacket area A around the third cylinder # 3, and the siamese jacket area B flows vertically upward and flows into the recessed portion 22 around the third cylinder # 3 and is divided into a flow for cooling the lower surface of the cylinder head 2 (the inner surface of the recessed portion 22 and the lower surface of the recessed portion partition wall 22d). . Similarly to the above-described case, the cooling water diverted to the recessed portion 22 passes through the third openings 34A and 34B of the cylinder head gasket 3 and flows through the main jacket region A around the third cylinder # 3. The cooling water merges and flows toward the siamese jacket region B between the third cylinder # 3 and the fourth cylinder # 4. Further, the flow of the cooling water flowing into the siamese jacket region B between the third cylinder # 3 and the fourth cylinder # 4 is the same as that described above.

  Then, the cooling water that has cooled the fourth cylinder # 4 passes through the communication holes 35 and 35 formed in the cylinder head gasket 3 and the introduction openings 23 and 23 formed in the cylinder head 2, and this cylinder head 2 It will be introduced into the internal water jacket 25. The cooling water that has flowed into the water jacket 25 inside the cylinder head 2 is taken out of the cylinder head 2 and recovered toward the radiator after the cylinder head 2 is cooled.

  Since the same cooling water passage 4 is formed around the first cylinder # 1 as described above, a part of the cooling water introduced from the cooling water inlet passage 12a is the same as in the above case. In addition, the introduction into the cooling water passage 4 contributes to the cooling of the lower surface of the cylinder head 2.

  As described above, also in the present embodiment, the cooling water passage 4 formed between the cylinder head 2 and the cylinder head gasket 3 is formed on the lower surface of the cylinder head 2 as in the case of the first embodiment. It is obtained as a dedicated passage for cooling, and is in a rectified state that is less affected by the flow (turbulent flow) of the cooling water in the water jacket 12. Further, in the cooling water passage 4, comparison is made from the first openings 32A and 32B of the cylinder head gasket 3 serving as the upstream opening toward the third openings 34A and 34B of the cylinder head gasket 3 serving as the downstream opening. Cooling water with a high flow rate is flowing. Therefore, the lower surface of the cylinder head 2 can be effectively cooled, and the lower surface of the cylinder head 2 and the siamese portion 15 between the cylinders can both be effectively cooled.

(Third embodiment)
Next, a third embodiment will be described. Since the configuration of the cylinder block 1 has been described above, only the configuration of the cylinder head 2 and the cylinder head gasket 3 and the shape of the cooling water passage 4 will be described here.

-Configuration of cylinder head 2-
FIG. 9 is a view corresponding to FIG. 2 in the present embodiment (a view showing the lower surface of the cylinder head 2).

  This cylinder head 2 is also made of an aluminum alloy, and has concave portions 22, 22,... For forming the cooling water passage 4 characterized by the present embodiment at a plurality of locations on the lower surface thereof. Further, as a difference from the above embodiments in the cylinder head 2 according to the present embodiment, the lower surface of the cylinder head 2 and the water jacket 25 are provided at the locations where the first recessed portions 22a are formed in the above embodiments. A through hole 22A is formed.

  Further, even in the recessed portion 22 and the through hole 22 </ b> A in the present embodiment, the recessed portion 22 and the through hole 22 </ b> A are formed at a part of the position corresponding to the open portion of the water jacket 12 in the cylinder block 1. The cooling water that is a part of the cooling water flowing through the water jacket 12 of the cylinder block 1 and that has passed through openings 32A and 32B formed in the cylinder head gasket 3 described later passes through the water jacket 25 through the through hole 22A. The cooling water that has flowed through the flow path formed between the gasket plates 3A and 3B flows into the recessed portion 22 (details will be described later). Hereinafter, the through holes 22A and the recessed portions 22 will be described.

  The through holes 22A, 22A,... Are formed at a total of eight locations on the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  .. Are also formed at a total of eight locations on the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4. For this reason, here, in particular, a description will be given on behalf of the recessed portion 22 formed on the exhaust side of the second cylinder # 2.

  As shown in FIG. 9, the recessed portion 22 is formed at a location corresponding to the formation position of the second recessed portion 22 b in each embodiment described above. The concave shape is the same as that of the second concave portion 22b. In addition, a communication path 22 c that connects the water jacket 25 formed inside the cylinder head 2 and the recess 22 is formed at a substantially central position in the longitudinal direction of the recess 22. The inner diameter of the communication path 22c is set to be relatively small (for example, about 5 mm). For this reason, a part of the cooling water (see arrow D in FIG. 12) flowing into the recessed portion 22 passes through the communication path 22 c and flows into the water jacket 25 inside the cylinder head 2 to cool the cylinder head 2. Has been. The concave portions 22 configured as described above are formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (the right side in FIG. 9) of the fourth cylinder # 4, introduction openings 23, 23 similar to those in the above embodiments are formed in two places.

  The same head bolt holes 24, 24,... Are formed at positions corresponding to the head bolt holes 16, 16,.

-Configuration of cylinder head gasket 3-
In the cylinder head gasket 3 according to this embodiment, the formation positions of the openings 32A to 34A and 32B to 34B in the upper gasket plate 3A and the lower gasket plate 3B constituting the cylinder head gasket 3 are different from each other. 10 is a plan view of the upper (cylinder head 2 side) upper gasket plate 3A, and FIG. 11 is a plan view of the lower (cylinder block 1 side) lower gasket plate 3B. Hereinafter, each gasket plate 3A, 3B is demonstrated.

  As shown in FIG. 10, the upper gasket plate 3A is formed with a plurality of openings 32A, 33A, 34A corresponding to a part of the formation position of the water jacket 12 formed in the cylinder block 1. A cooling water flow path is formed by the openings 32A, 33A, and 34A and the through hole 22A and the recessed portion 22 of the cylinder head 2 described above.

  Hereinafter, the openings 32A to 34A will be described. Since the opening positions of the openings 32A, 33A, and 34A formed on the intake side and the exhaust side around the first cylinder # 1 to the fourth cylinder # 4 in the upper gasket plate 3A are the same, here, In particular, the openings 32A, 33A, 34A formed on the exhaust side of the second cylinder # 2 will be described as a representative.

  As shown in FIG. 10, these openings 32A, 33A, and 34A are formed as a set on the exhaust side of the second cylinder # 2. Specifically, the first opening 32A formed corresponding to the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 and the downstream side (the first opening 32A). A second opening 33A formed on the third cylinder # 3 side) and a third opening 34A formed further downstream (the third cylinder # 3 side) than the second opening 33A are formed. .

  The first opening 32A is set to have an opening area smaller than the opening area of the through hole 22A formed in the cylinder head 2, thereby adjusting (limiting) the amount of cooling water flowing into the through hole 22A. ing. The second opening 33A is formed corresponding to a region extending from the lower surface of the cylinder head 2 (the lower surface in the region between the formation position of the through hole 22A and the formation position of the recess 22) to the recess 22. It is formed with a relatively long opening. The third opening 34A is formed corresponding to the downstream end (end on the third cylinder # 3 side) of the recessed portion 22 formed on the lower surface of the cylinder head 2.

  Each of the openings 32A, 33A, and 34A configured in this way is formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (the right side in FIG. 10) of the fourth cylinder # 4, communication holes 35, 35 similar to the cylinder head gasket 3 in each of the above embodiments are formed.

  On the other hand, as shown in FIG. 11, the lower gasket plate 3B has a plurality of openings 32B, 33B, 34B corresponding to a part of the formation position of the water jacket 12 formed in the cylinder block 1. The openings 32B, 33B, 34B and the above-described through holes 22A and the recessed portions 22 of the cylinder head 2 form a cooling water flow path.

  Hereinafter, the openings 32B to 34B will be described. Since the positions of the openings 32B, 33B, and 34B formed on the intake side and the exhaust side around the first cylinder # 1 to the fourth cylinder # 4 in the lower gasket plate 3B are the same as each other, here too In particular, the openings 32B, 33B, and 34B formed on the exhaust side of the second cylinder # 2 will be described as a representative.

  As shown in FIG. 11, these openings 32B, 33B, 34B are formed as a set on the exhaust side of the second cylinder # 2. Specifically, a first opening 32B formed corresponding to the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 and a downstream side (first number) from the first opening 32B. A second opening 33B formed on the third cylinder # 3 side) and a third opening 34B formed further downstream (the third cylinder # 3 side) than the second opening 33B are formed. .

  The first opening 32B is set to have a larger opening area than the first opening 32A of the upper gasket plate 3A. The second opening 33 </ b> B is formed at a position facing the recessed portion 22 formed on the lower surface of the cylinder head 2. The length of the second opening 33B in the lower gasket plate 3B is set to be shorter than the length of the second opening 33A in the upper gasket plate 3A. The third opening 34B is formed corresponding to the downstream end (end on the third cylinder # 3 side) of the recessed portion 22 formed in the lower surface of the cylinder head 2.

  As a feature of the lower gasket plate 3B, a region between the first opening 32B and the second opening 33B is formed as a curved portion 37 curved downward, and the cylinder head gasket 3 is connected to the cylinder block 1. When assembled with the cylinder head 2, the curved portion 37 retreats downward from the lower surface of the cylinder head 2 to form a cooling water passage with the lower surface of the cylinder head 2. (See FIG. 12). Further, the downstream end of the curved portion 37 is slightly curved upward (cylinder head 2 side), and guides the cooling water flowing through the cooling water passage obliquely upward (toward the cylinder head 2 side). It is like that.

  Further, as another feature of the lower gasket plate 3B, a cooling water guide 38 that is a region between the second opening 33B and the third opening 34B and in the vicinity of the third opening 34B is curved downward. It is formed as.

  Each of the openings 32B, 33B, and 34B configured as described above is formed at a total of eight locations on each of the intake side and the exhaust side of the first cylinder # 1 to the fourth cylinder # 4.

  Further, on the rear side (the right side in FIG. 11) of the fourth cylinder # 4, communication holes 35, 35 similar to the upper gasket plate 3A are formed.

  The same head bolt holes 36, 36,... Are formed at positions corresponding to the head bolt holes 16, 16,... Of the cylinder block 1 at a plurality of locations on the gasket plates 3A, 3B.

  As described above, the cylinder head gasket 3 is configured by integrally stacking the gasket plates 3A and 3B in which the openings 32A to 34A and 32B to 34B are formed.

-Explanation of cooling water passage 4 and cooling water flow-
Next, the cooling water passage 4 formed by integrally assembling the cylinder head 2 and the cylinder head gasket 3 configured as described above to the cylinder block 1 and the cooling water flow in the cooling water passage 4 will be described. Even in the present embodiment, the cooling water flow in the Siamese jacket region B and its peripheral part is the most characteristic. Therefore, the cooling water flow in this part will be mainly described.

  12 is a cross-sectional view at a position corresponding to the line IV-IV in FIG. 1 in a state where the cylinder block 1, the cylinder head gasket 3, and the cylinder head 2 are integrally assembled by a head bolt.

  As shown in FIG. 12, when the cylinder block 1, the cylinder head gasket 3, and the cylinder head 2 are assembled together, the water jacket 12 of the cylinder block 1 and the recesses formed on the lower surface of the cylinder head 2. The portion 22 is isolated by the cylinder head gasket 3 and partially communicated (at positions where the openings 33A, 33B, 34A, 34B are formed in the cylinder head gasket 3).

  Specifically, in the Siamese jacket region B, the water jacket 12 of the cylinder block 1 communicates with the water jacket 25 in the vertical direction through the through holes 22A of the cylinder head 2 through the first openings 32A and 32B of the cylinder head gasket 3. It has become a state.

  Further, in the upstream portion of the main jacket region A close to the siamese jacket region B, the water jacket 12 of the cylinder block 1 is formed in the recessed portion 22 of the cylinder head 2 by the second openings 33A and 33B of the cylinder head gasket 3. It is in a state of communicating in the vertical direction.

  More specifically, as the shape of the cooling water passage in this portion, the second opening 33A formed in the upper gasket plate 3A as described above is formed so as to face the lower surface of the cylinder head 2. On the other hand, a curved portion 37 is formed in a region between the first opening 32B and the second opening 33B in the lower gasket plate 3B. For this reason, when the cylinder head gasket 3 configured by superposing the upper gasket plate 3A and the lower gasket plate 3B is assembled between the cylinder block 1 and the cylinder head 2, the lower surface of the cylinder head 2 is In addition to being exposed in the second opening 33A of the upper gasket plate 3A, the curved portion 37 of the lower gasket plate 3B recedes downward from the lower surfaces of the upper gasket plate 3A and the cylinder head 2, and cooling water is interposed therebetween. A passage is formed. That is, a cooling water passage formed between the lower surfaces of the upper gasket plate 3A and the cylinder head 2 and the curved portion 37 of the lower gasket plate 3B communicates the water jacket 12 and the recessed portion 22. .

  Further, in the downstream portion of the main jacket region A away from the siamese jacket region B, the water jacket 12 of the cylinder block 1 is recessed by the third openings 34A and 34B of the cylinder head gasket 3. It is in the state where it communicated in the vertical direction.

  As the cooling water flow in the cooling water passage 4 formed in this way, the cooling water introduced from the cooling water inlet passage 12a first moves the water jacket 12 of the cylinder block 1 in the horizontal direction as the water pump is driven. Flowing into. That is, the first cylinder # 1 is cooled by flowing in the main jacket region A around the first cylinder # 1 in the horizontal direction.

  Then, after cooling the first cylinder # 1, a part of the cooling water flowing into the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2 remains as it is in the cylinder block 1. By flowing in the water jacket 12 in the horizontal direction and flowing in the main jacket region A around the second cylinder # 2, it contributes to cooling of the second cylinder # 2. The other coolant flows vertically upward in the siamese jacket region B between the first cylinder # 1 and the second cylinder # 2, and passes through the first openings 32A and 32B of the cylinder head gasket 3 to form a cylinder. It flows into the water jacket 25 through the through hole 22A of the head 2 (see arrow C in FIG. 12). On the other hand, part of the cooling water that has flowed vertically upward in the Siamese jacket region B hits the lower surface of the edge of the first opening 32A in the upper gasket plate 3A, changes the streamline direction to the horizontal direction, and flows toward the recessed portion 22. . At this time, it passes through the cooling water passage formed between the curved portion 37 of the lower gasket plate 3B and the lower surface of the cylinder head 2, and then flows into the recessed portion 22 while being guided by the curved portion 37. (See arrow D in FIG. 12). By this flow, in addition to the inner wall surface of the recessed portion 22, the lower surface of the cylinder head 2 is directly cooled by the cooling water.

  Most of the cooling water flowing through the recessed portion 22 reaches the downstream end of the recessed portion 22 and passes through the third openings 34A and 34B of the cylinder head gasket 3 while changing the streamline direction downward. Then again flows into the water jacket 12 of the cylinder block 1 (see arrow E in FIG. 12). As a result, the cooling water (see arrow F in FIG. 12) flowing through the main jacket region A around the second cylinder # 2 joins, and between the second cylinder # 2 and the third cylinder # 3. Will flow toward the Siamese jacket region B.

  Further, as described above, since the cooling water guide 38 is formed in the lower gasket plate 3B, the cooling water merging portion flows through the main jacket region A around the second cylinder # 2. The flowing cooling water (arrow F in FIG. 12) is deflected obliquely downward. For this reason, the cooling water flowing into the water jacket 12 of the cylinder block 1 from the third openings 34A and 34B of the cylinder head gasket 3 can be smoothly received without receiving resistance by the cooling water flowing through the main jacket region A. It flows into the water jacket 12. Thereby, the flow-rate fall of the cooling water in the cooling water channel | path 4 can be prevented.

  As described above, also in the present embodiment, in the cooling water passage 4 formed between the recessed portion 22 and the cylinder head gasket 3 as in the case of the second embodiment described above, the curved portion extends from the first opening 32B. Since the space extending to the upstream end of 37 serves as an inflow port and the third openings 34A and 34B serve as outflow ports, the cooling water flows at a relatively high flow rate without stagnation of the cooling water. The lower surface of the substrate is efficiently cooled.

  The water jacket 12 and the recessed portion 22 of the cylinder block 1 communicate with each other through the second openings 33A and 33B of the cylinder head gasket 3. The effect of forming the second openings 33A and 33B is the same as in the case of the first embodiment.

  Further, a part of the cooling water flowing through the recessed portion 22 passes through the communication path 22c formed in the cylinder head 2 and flows into the water jacket 25 of the cylinder head 2 to cool the cylinder head 2 (FIG. 12). (See arrow G).

  After flowing through the main jacket region A around the second cylinder # 2, the flow of the cooling water flowing into the siamese jacket region B between the second cylinder # 2 and the third cylinder # 3 is also possible. This is the same as described above. That is, the flow contributing to cooling of the third cylinder # 3 by flowing in the water jacket 12 of the cylinder block 1 in the horizontal direction and flowing in the main jacket area A around the third cylinder # 3, and the siamese jacket area B flows vertically upward, a part flows into the water jacket 25 and the other flows into the recessed part 22 in the periphery of the third cylinder # 3 so as to cool the lower surface of the cylinder head 2. Similarly to the above-described case, the cooling water diverted to the recessed portion 22 passes through the third openings 34A and 34B of the cylinder head gasket 3 and flows through the main jacket region A around the third cylinder # 3. The cooling water merges and flows toward the siamese jacket region B between the third cylinder # 3 and the fourth cylinder # 4. Further, the flow of the cooling water flowing into the siamese jacket region B between the third cylinder # 3 and the fourth cylinder # 4 is the same as that described above.

  Then, the cooling water that has cooled the fourth cylinder # 4 passes through the communication holes 35 and 35 formed in the cylinder head gasket 3 and the introduction openings 23 and 23 formed in the cylinder head 2, and this cylinder head 2 It will be introduced into the internal water jacket 25. The cooling water that has flowed into the water jacket 25 inside the cylinder head 2 is taken out of the cylinder head 2 and recovered toward the radiator after the cylinder head 2 is cooled.

  Since the same cooling water passage 4 is formed around the first cylinder # 1 as described above, a part of the cooling water introduced from the cooling water inlet passage 12a is the same as in the above case. In addition, the introduction into the cooling water passage 4 contributes to the cooling of the lower surface of the cylinder head 2.

  As described above, also in this embodiment, the cooling water passage 4 formed between the cylinder head 2 and the cylinder head gasket 3 cools the lower surface of the cylinder head 2 in the same manner as in the above embodiments. It is obtained as a dedicated passage for the purpose, and is in a rectified state that is less affected by the flow (turbulent flow) of the cooling water in the water jacket 12. Further, in the cooling water passage 4, the cylinder head gasket 3 serving as an opening on the downstream side from the space extending from the first opening 32 </ b> B of the cylinder head gasket 3 serving as the upstream opening to the upstream end of the curved portion 37. Cooling water having a relatively high flow rate flows toward the third openings 34A and 34B. Therefore, the lower surface of the cylinder head 2 can be effectively cooled, and the lower surface of the cylinder head 2 and the siamese portion 15 between the cylinders can both be effectively cooled.

-Other embodiments-
Each embodiment described above demonstrated the case where this invention was applied to the in-line 4-cylinder gasoline engine for motor vehicles. The present invention is not limited to this, and can be applied to other types of gasoline engines and diesel engines. Moreover, it is applicable not only to automobiles but also to engines used for other purposes. Also, the number of cylinders and the engine type (separate types such as in-line type, V type, and horizontally opposed type) are not particularly limited.

It is a top view of the cylinder block in the engine concerning a 1st embodiment. It is a bottom view of the cylinder head in the engine concerning a 1st embodiment. It is a top view of the cylinder head gasket in the engine concerning a 1st embodiment. It is sectional drawing in the position corresponding to the IV-IV line of FIG. 1 in the engine which concerns on 1st Embodiment. It is a figure equivalent to FIG. 2 in the engine which concerns on 2nd Embodiment. It is a top view of the upper gasket plate in the engine concerning a 2nd embodiment. It is a top view of the lower gasket plate in the engine which concerns on 2nd Embodiment. It is a figure equivalent to FIG. 4 in 2nd Embodiment. It is a figure equivalent to FIG. 2 in the engine which concerns on 3rd Embodiment. It is a figure equivalent to FIG. 6 in 3rd Embodiment. It is a figure equivalent to FIG. 7 in 3rd Embodiment. It is a figure equivalent to FIG. 8 in 3rd Embodiment. It is a figure equivalent to FIG. 4 in a prior art example. It is a figure equivalent to FIG. 4 in another prior art example.

Explanation of symbols

1 Cylinder block 11 Cylinder bore 12 Water jacket (cooling water passage)
15 Siamese part 2 Cylinder head 25 Water jacket (cooling water passage)
3 Cylinder head gasket 3A Upper gasket plate 3B Lower gasket plate 32 First opening (cooling water introduction opening)
33 Second opening 34 Third opening (cooling water outlet opening)
37 Curved portion 38 Cooling water guide portion 4 Cylinder head cooling water passage 4A Step portion

Claims (6)

In the cooling structure of the internal combustion engine configured in the open deck type in which the cooling water passage in the cylinder block and the cooling water passage in the cylinder head communicate with each other through an opening formed in the cylinder head gasket,
A cylinder head cooling water passage extending in the extending direction of the facing surface is formed between the facing surface facing the cylinder block and the cylinder head gasket in the cylinder head.
The cylinder head gasket is formed with a cooling water introduction opening located on one end side in the extending direction of the cylinder head cooling water passage and a cooling water outlet opening located on the other end side, respectively. The cooling structure for an internal combustion engine, characterized in that a cooling water flow from the cooling water introduction opening toward the cooling water outlet opening is generated. In the internal combustion engine cooling structure according to claim 1,
The cylinder block has a Siamese structure,
The cooling water introduction opening of the cylinder head gasket is formed in the vicinity of the siamese portion, which is the boundary between adjacent cylinder bores, and flows from the cooling water passage in the cylinder block toward the cylinder head in the vicinity of this siamese portion. A cooling structure for an internal combustion engine, wherein the cooling water is guided to a cooling water passage for a cylinder head. In the internal combustion engine cooling structure according to claim 1 or 2,
The cylinder head gasket is formed by laminating a plurality of plates, and the cylinder head coolant is formed by bending the plate located on the cylinder block side so as to recede from the plate located on the cylinder head side. A passage is formed, and the mating surface of the cylinder head is exposed to the cylinder head cooling water passage in a region facing the curved portion of the plate member located on the cylinder block side of the plate member located on the cylinder head side. An internal combustion engine cooling structure, wherein an opening is formed, and cooling water flowing through the cooling water passage is in direct contact with the exposed mating surface. In the cooling structure for an internal combustion engine according to claim 1, 2, or 3,
At the edge of the cooling water outlet opening in the cylinder head gasket, at the merged portion of the cooling water flowing through the cooling water passage in the cylinder block and the cooling water led out from the cooling water outlet opening to the cooling water passage in the cylinder block, A cooling structure for an internal combustion engine, characterized in that a cooling water guide portion for deflecting a flow line direction of the cooling water flowing through the cooling water passage in the cylinder block in a direction away from the cooling water outlet opening is formed. In the internal combustion engine cooling structure according to any one of claims 1 to 4,
On the inner surface of the cooling water passage for the cylinder head, the cross-sectional area of the cooling water outlet opening side is made larger than the cross-sectional area of the cooling water introduction opening side as the cross-sectional area of the cross section substantially orthogonal to the cooling water flow direction inside the passage. A cooling structure for an internal combustion engine, characterized in that a step portion is provided. A cylinder head gasket used for a cooling structure of an internal combustion engine according to any one of claims 1 to 5,
In the cylinder head cooling water passage, a cooling water introduction opening and the other end located on one end side in the extending direction of the cylinder head cooling water passage so that a cooling water flow along the extending direction of the facing surface is generated. A cylinder head gasket characterized in that a cooling water outlet opening located on each side is formed.

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