JP2006242030A - Engine cylinder head structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine cylinder head structure efficiently improving cooling performance in an exhaust side of a water jacket as compared with an intake side while improving cooling performance of a spark plug hole wall by making limited cooling water efficiently flow. <P>SOLUTION: A first flow restriction longitudinal bead 81 is provided to restrict flow of cooling water and increase flow speed at this section. Since a cooling passage 35 opens at a flow in zone 31c between exhaust ports 14, 14, flow speed at this section is increased and cooling water is sucked out from the cooling passage 35 by venturi effect. Consequently, cooling performance in the exhaust side is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine cylinder head structure, and more particularly to an engine cylinder head structure that improves cooling performance.

  2. Description of the Related Art In recent years, a valve mechanism for an engine has frequently used a valve mechanism with two intake valves and two exhaust valves with high intake and exhaust efficiency.

  In such an engine, it is desired to increase the output together with the compactness of the engine body. Therefore, it is required to cope with the heat load of the engine accompanying the increase in output.

  In particular, it is important to improve the cooling performance around the combustion chamber and the exhaust port, and various techniques for improving the cooling performance around this have been proposed.

In Patent Document 1 below, in order to improve the cooling performance of the upper part of the combustion chamber, the cross-sectional area of the plug tower portion (cylindrical spark plug hole wall) of the cylinder head is changed from the combustion chamber side to the upper deck side (lower side to upper side). In order to increase the cooling performance, the flow rate of the cooling water on the combustion chamber side of the water jacket is increased as compared with that on the upper deck side.
JP 2003-314357 A

  By the way, since the total flow rate of the cooling water of the engine is determined by the performance of a water pump or the like, it becomes a problem how to flow the cooling water in order to efficiently improve the cooling performance.

  In general, the engine has a higher cooling demand on the exhaust side than on the intake side. However, according to the above-mentioned Patent Document 1, only the countermeasure for increasing the flow velocity on the combustion chamber side over the entire water jacket is taken. For this reason, it is not possible to obtain a cooling performance corresponding to the difference in cooling requirements between the intake side and the exhaust side.

  Furthermore, although it is necessary to reduce the temperature around the spark plug, in Patent Document 1, no consideration is given to the cooling performance of the spark plug hole wall itself.

  In addition, in order to improve the cooling performance between the two exhaust ports, a cooling passage for guiding the cooling water from the cylinder block side may be formed between the exhaust ports with a drill hole. Also, Patent Document 1 does not disclose anything.

  In view of this, the present invention improves the cooling performance of the spark plug hole wall by efficiently flowing the limited cooling water in the cylinder head structure of the engine while improving the cooling performance on the exhaust side of the water jacket. An object of the present invention is to provide a cylinder head structure for an engine that can be improved more efficiently than the above.

In the cylinder head structure of the engine of the present invention, a valve mechanism is constituted by two intake valves and two exhaust valves, and a plurality of cylinders having ignition plugs arranged substantially in the center are arranged in the column direction, and the ignition plug hole walls of the cylinders are arranged. And a main water jacket in which cooling water flows in the cylinder row direction and an exhaust side auxiliary water jacket in which cooling water flows in the cylinder row direction around the exhaust port wall, the main water jacket and the exhaust side sub water An engine cylinder head structure configured such that a jacket communicates between cylinders,
In the main water jacket, the minimum passage cross-sectional area from the spark plug hole wall to the exhaust port wall side and the minimum passage cross-sectional area from the spark plug hole wall to the intake port wall side are the portions facing the exhaust port wall of the spark plug hole wall. The first vertical bead portion formed and the second vertical bead portion formed at the portion facing the intake port wall of the spark plug hole wall are set so that the exhaust side becomes larger, and the cylinder is interposed between the pair of exhaust ports. A cooling passage having one end opened on the lower surface of the head and the other end opened to face the spark plug hole wall, and the first vertical bead portion is located upstream of the main water jacket in the cooling water flow direction. It is formed in the spark plug hole wall facing the port wall.

  According to the above configuration, the main water jacket is minimized by the first vertical bead portion formed in the portion facing the exhaust port wall of the spark plug hole wall and the second vertical bead portion formed in the portion facing the intake port wall. Since the passage cross-sectional area is set larger on the exhaust side, the flow rate of the cooling water on the exhaust side can be made larger than the flow rate on the intake side while suppressing the total flow rate of the main water jacket.

  Further, the first vertical bead portion and the second vertical bead portion come into contact with the flowing cooling water, so that the cooling performance of the spark plug hole wall is also improved.

  And this 1st vertical bead part is formed in the spark plug hole wall facing the exhaust port wall located upstream of the cooling passage, so that the cooling water upstream of the opening on the spark plug hole wall side of the cooling passage As a result, the flow rate of the cooling water near the opening of the cooling passage is increased, and the cooling water is sucked out by the venturi effect, so that the cooling performance on the exhaust side can be improved.

  Here, the shape of the first vertical bead portion and the second vertical bead portion is not particularly limited, but in order to increase the flow rate of the cooling water, it is desirable to bulge as gently as possible. It is preferable to configure.

  Further, the second vertical bead portion may be formed on any intake port wall side of the two intake valves as long as the flow rate of the main water jacket can be reduced at a position facing the intake port wall.

  In one embodiment of the present invention, the exhaust side passage portion is more preferably the exhaust side passage portion restricted by the first vertical bead portion and the intake side passage portion restricted by the second vertical bead portion. Are formed higher in the vertical direction, and the first vertical bead portion is formed longer in the vertical direction than the second vertical bead portion.

  According to the above configuration, the exhaust side passage portion is formed to be higher in the vertical direction than the intake side passage portion, and the first vertical bead portion is formed to be longer than the second vertical bead portion, thereby being narrowed by the exhaust side passage portion. Thus, the range in which the flow rate of the cooling water increases can be widened from a low position to a high position in the vertical direction.

  For this reason, the suction of the cooling passage which guides the cooling water between the cylinder block side and the exhaust port (from the lower side to the upper side) can be further promoted by widening the range where the venturi effect extends.

  Therefore, the cooling performance by the cooling passage between the exhaust ports can be further enhanced, and the cooling performance can be more effectively enhanced.

  In one embodiment of the present invention, the lateral width of the exhaust-side passage portion is set to a width that substantially matches the entire vertical direction.

  According to the above configuration, since the horizontal width of the exhaust side passage portion has a width that substantially matches the entire vertical direction, the improvement in the flow rate of the cooling water by the first vertical bead portion is substantially uniform throughout the exhaust side passage portion. Will occur.

  For this reason, also in a combustion chamber side (lower side) part, a cooling water flows appropriately and the cooling performance by the side of a combustion chamber improves.

  Therefore, while improving the cooling performance on the exhaust side, the cooling performance on the combustion chamber side with the most severe heat load can be improved.

  In one embodiment of the present invention, the second vertical bead portion is formed in a spark plug hole wall facing an intake port wall located downstream of the main water jacket in the coolant flow direction.

  According to the said structure, a 2nd vertical bead part will be formed in the site | part which faces the intake port wall located in the downstream.

  For this reason, the second bead portion has no influence on the so-called cooling water inflow region between the intake ports.

  Therefore, “stagnation” due to a partial increase in the flow velocity does not occur in the inflow region between the intake ports, and the cooling water flows in a rectified state, so that appropriate cooling performance on the intake side can be obtained.

  That is, in the inflow region between the intake ports, a cooling passage is not formed like between the exhaust ports. Therefore, if the flow velocity increases partly, a “vortex” is generated and the cooling water becomes “stagnation”. However, the occurrence of such “stagnation” can be suppressed by forming the second vertical bead portion in the spark plug hole wall facing the intake port wall on the downstream side.

  In one embodiment of the present invention, an intake side sub-water jacket that communicates between the main water jacket and the cylinder is provided below the intake port in the direction of each cylinder, and between the pair of intake ports and A fuel injection valve hole wall for mounting a combustion injection valve whose front end faces the combustion chamber is formed below the intake port, and the fuel injection valve hole wall is set in contact with the intake side sub-water jacket. is there.

According to the above configuration, the intake side auxiliary water jacket is provided below the intake port, and the fuel injection valve is cooled by the intake side auxiliary water jacket by bringing the fuel injection valve hole wall into contact with the intake side auxiliary water jacket. Will be.
For this reason, the fuel injection valve can also be cooled, and thermal damage to the fuel injection valve can be prevented.

  In particular, as described above, the flow rate of the main water jacket is reduced by the first vertical bead portion and the second vertical bead portion, and the flow rate to the intake side auxiliary water jacket is increased. Cooling performance can be enhanced.

  Therefore, the cooling performance of the fuel injection valve can also be improved, and the cylinder head can be efficiently cooled by the limited flow rate of the cooling water.

  According to the present invention, the flow rate of the cooling water on the exhaust side can be made larger than the flow rate on the intake side while suppressing the flow rate of the main water jacket. In addition, the cooling performance of the spark plug hole wall can be improved. Further, the first vertical bead portion is formed in the spark plug hole wall facing the exhaust port wall located upstream of the cooling passage, so that the cooling water upstream of the cooling passage is throttled by the first vertical bead portion. Thus, the flow rate of the cooling water increases near the opening of the cooling passage, and the cooling water in the cooling passage is effectively sucked out.

  Therefore, in the engine cylinder head structure, the cooling performance of the water jacket exhaust side is improved compared to the intake side while the cooling performance of the spark plug hole wall is improved by efficiently flowing the limited cooling water. Can be improved efficiently.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram of a cooling path X of an engine E that employs the cylinder head structure of the present invention.

  As shown in FIG. 1, the cooling path X of the engine E includes a radiator 1 that cools the heated cooling water, a thermostat 2 that is installed downstream thereof to appropriately control the flow rate of the cooling water, and a downstream thereof. And a water pump 3 for flowing cooling water, an engine cylinder block 4 installed downstream thereof and cooled by cooling water, and a cylinder head 5 similarly cooled by cooling water. Yes, the engine E is cooled by circulating cooling water through this path. Reference numeral 6 denotes a cooling fan for cooling the radiator 1.

  The flow rate of the cooling water flowing through the cooling path X is limited to a predetermined value depending on the performance of the water pump 3 and the like. Therefore, the cooling performance of the engine E changes depending on how the cooling water is distributed and flowed. To do.

  In the present embodiment, the cooling performance of the engine E is enhanced by devising the structure of the cylinder head 5 of the engine E to efficiently flow the cooling water.

  2 is a partially cutaway plan view of the cylinder head 5, FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 (cross-sectional view between ports), and FIG. 4 is a cross-sectional view taken along line BB in FIG. 5 is a cross-sectional view taken along the line CC of FIG. 2 (cross-cylinder cross-sectional view), FIG. 6 is a bottom view of the cylinder head 5, FIG. 7A is a plan view of the cylinder block 4, and FIG. ) Is a plan view of the gasket 7.

  The cylinder head 5 of this embodiment is a cylinder head 5 of an in-line four-cylinder engine E in which four cylinders are arranged in series. The cylinder head 5 is attached to the upper surface of the cylinder block 4 via a gasket 7.

  In this embodiment, the longitudinal direction of the cylinder head 5, that is, the cylinder row direction is the engine longitudinal direction, and the output end side (upper side in FIG. 2) of the crankshaft is referred to as the engine rear side. The lower side of FIG. 2 is called the engine front side, and the right side (right side of FIG. 2) when viewed from the rear side of the engine is called the engine intake side, and the opposite side (left side of FIG. 2) is the engine exhaust side. Shall be called. 6 and 7, the front side, the rear side, the intake side, and the exhaust side are described to specify the direction in the engine E.

  The bottom deck 5a, which is the bottom surface of the cylinder head 5, is formed with a combustion chamber ceiling 11 for closing the cylinder 10 (see FIG. 7) formed in the cylinder block 4 from above as shown in FIGS. ing.

  As shown in FIG. 3, each combustion chamber ceiling portion 11 has a so-called pent roof shape, and a spark plug (not shown) is attached to the cylinder center portion from above the cylinder head 5. A plug hole 12 is formed to be disposed vertically downward along the axis.

  In addition, as shown in FIG. 2, an intake port 13 is opened on the engine intake side and an exhaust port 14 is opened on the engine exhaust side on the inclined surface of each combustion chamber ceiling portion 11, as shown in FIG. Yes. Two intake valves and two exhaust valves 15a and 15b (two-dot chain lines in FIG. 4) are arranged at the open ends of the ports 13 and 14, respectively.

  As shown in FIG. 4, the two intake ports 13 and 13 extend substantially linearly from the combustion chamber obliquely upward and open independently from each other on the engine intake side of the cylinder head 5. On the other hand, the two exhaust ports 14, 14 join together in the middle and extend substantially horizontally, and are open on the engine exhaust side surface of the cylinder head 5.

  A nozzle hole 16 for mounting a fuel injection nozzle (not shown) for directly injecting fuel into the combustion chamber is formed on the engine intake side of the bottom deck 5a as shown in FIG.

  As shown in FIG. 6, the intervals between the cylinders 10 (see FIG. 7) are very narrow, and the inter-cylinder portions 17 of the bottom deck 5a are thin in the cylinder row direction.

  As shown in FIG. 3, the cylinder head 5 is formed with a middle deck 5b in the vicinity of a substantially central portion in the vertical direction. Above the middle deck 5b, an intake cam shaft and an exhaust cam shaft (see FIG. 3). The head side water jacket 20 defined by the middle deck 5b, the bottom deck 5a, the jacket side wall 18 and the like is formed below the middle deck 5b.

  The middle deck 5b is provided with two disposing holes 19a and 19b for disposing the intake valve 15a and the exhaust valve 15b on the intake side and the exhaust side, respectively, with the plug holes 12 interposed therebetween. A head bolt through hole 21 and a bolt boss portion 22 for inserting a head bolt (not shown) for attaching the cylinder head 5 to the cylinder block 4 are formed so as to surround each cylinder.

  Above the middle deck 5b, an intake side camshaft and an exhaust side camshaft (not shown) for opening and closing the intake valve 15a and the exhaust valve 15b, respectively, correspond to above the arrangement holes 19a and 19b. Are arranged in parallel with each other so as to extend in the front-rear direction of the engine E.

  The cylinder head 5 is formed with bearing portions 23 and 24 on both the left and right sides of the plug hole 12 for each cylinder, and the intake side cam shaft and the exhaust side cam are formed by the intake side and exhaust side bearing portions 23 and 24. The shaft is supported.

  As shown in FIG. 4 and the like, the head-side water jacket 20 is formed above the bottom deck 5a, the intake port 13 and the exhaust port 14 on the center side in the engine width direction, and the first combustion chamber ceiling portion at the forefront of the engine. 11, a main water jacket 31 extending in the cylinder row direction from the fourth combustion chamber ceiling portion 11 to the rearmost portion, and an intake side auxiliary water jacket extending in the cylinder row direction between each of the intake ports 13 and the bottom deck 5a. 32 and an exhaust side auxiliary water jacket 33 extending in the cylinder row direction between the exhaust ports 14 and the bottom deck 5a. These water jackets 31, 32, 33 communicate with each other through branch passages 34 provided between the cylinders.

  As shown in FIG. 4, the main water jacket 31 is partitioned by the middle deck 5b in the upper part thereof and by the bottom deck 5a in the lower part thereof. Further, both side portions thereof are partitioned by intake port walls 25 that define the intake ports 13, exhaust port walls 26 that define the exhaust ports 14, bolt bosses 21, and the like. Further, a plug hole wall 27 that defines a plug hole 12 standing in the vertical direction is formed at the center position in the engine width direction of the main water jacket 31.

  The main water jacket 31 is configured such that cooling water flows in the cylinder row direction from the front side of the engine to the rear side along the intake port walls 25, the exhaust port walls 26, and the plug hole walls 27. ing.

  As shown in FIG. 3, the intake side sub-water jacket 32 is formed between the intake port wall 25 and the nozzle hole wall 28 that defines the nozzle hole 16, and extends in the cylinder row direction. It extends to the front and rear ends of engine E. Like the main water jacket 31, the cooling water flows in the cylinder row direction from the front side of the engine to the rear side along the intake port walls 25 and the nozzle hole wall 28.

  As shown in FIG. 4, the exhaust side sub-water jacket 33 is formed between the exhaust port wall 26 and the bottom deck 5a, and extends in the cylinder row direction to the front and rear ends of the engine. . As with the other water jackets, the cooling water flows along the exhaust port walls 26 from the front side of the engine to the rear side in the cylinder row direction.

  As shown in FIG. 3, a water jacket on the cylinder block 4 side and a water jacket on the head side 20 are communicated between the pair of exhaust ports 14 and 14 of each cylinder, and the exhaust ports 14 and 14 are connected from the cylinder block 4 side. A cooling passage 35 formed by a through hole for introducing cooling water is provided therebetween.

  The cooling performance of the exhaust port 14 which is a passage for discharging high-temperature burned gas immediately after combustion by actively introducing cooling water between the pair of exhaust ports 14 and 14 from the cylinder block 4 side in the cooling passage 35. Is increasing.

  As shown in FIG. 7A, four cylinders 10 are connected to the cylinder block 4 in the cylinder row direction, and a plurality of peripheral water jackets 41 are formed around each cylinder. Each cylinder 10 is cooled. In addition, on the front end side of the engine, introduction water jackets for introducing cooling water from the cylinder block 4 to the cylinder head 5 side are formed on the intake side 42 and the exhaust side 43, respectively.

  A bolt hole 44 that is fastened and fixed when the cylinder head 5 is fixed and a positioning pin 45 that defines a fixing position are formed on the engine intake side and the engine exhaust side between the cylinders 10 of the cylinder block 4. ing.

  On the other hand, as shown in FIG. 7B, the gasket 7 is formed with four cylinder openings 71 corresponding to the respective cylinders, and correspondingly formed insertion openings 72 through which head bolts and the like are inserted. Yes.

  In addition, water jacket openings 73 and 74 corresponding to the introduction water jackets 42 and 43 are formed on the front side of the engine.

  The water jacket openings 73 and 74 are formed on the exhaust side 74 with a larger opening area, as is apparent from the view of FIG. By thus opening the exhaust side 74 large, the flow rate on the exhaust side can be increased.

  In addition, communication openings 75 are formed corresponding to the peripheral water jackets 41. The opening area of the communication opening 75 is extremely smaller than the water jacket openings 73 and 74 described above. For this reason, most of the cooling water from the cylinder block 4 side to the cylinder head 5 side is introduced through the water jacket openings 73 and 74.

  When the engine intake side and the engine exhaust side of the communication openings 75 are compared, the communication openings 75 on the exhaust side are formed larger. This is because on the exhaust side, it is necessary to introduce cooling water between the cooling passage 35 and the exhaust port as described above.

  Thus, in this embodiment, the flow position and flow rate of the cooling water flowing from the cylinder block 4 side to the cylinder head 5 side are determined by adjusting the opening area of each opening 73, 74, 75 of the gasket 7. Yes.

  On the other hand, as shown in FIG. 6, the water jacket on the cylinder head 5 side that receives the cooling water from the openings 73, 74, and 75 of the gasket 7 has intake water jackets 51 and 52 on the intake and exhaust sides formed at the front end of the engine. And a plurality of peripheral water jackets 53 formed on the periphery of each cylinder.

  Of these, the receiving water jackets 51 and 52 mainly receive the cooling water from the cylinder block 4 side, and the cooling water received from these portions is the main water jacket 31, the exhaust side auxiliary water jacket 33, and the intake side auxiliary jacket. It will flow into the water jacket 32. The other peripheral water jackets 53... Also flow slightly through the communication openings 75 of the gasket 7 described above, but hardly flow, so that the coolant in the cylinder head 5 reliably flows from the front side to the rear side of the engine. To occur.

  In the cylinder head 5 of this embodiment, the structure which adjusts the flow volume and flow velocity of the cooling water in the main water jacket 31 is employ | adopted. This structure will be described with reference to FIGS. 8 is a sectional view taken along the line D-D in FIG. 2 and is a sectional view around the plug hole wall 27. FIG. 9 is a plan view showing the main water jacket 31 around the plug hole wall 27. FIG. FIG. 11 is a perspective view around the plug hole wall 27 as seen from the intake side. In addition, the arrow shown to each figure is a flow direction of cooling water.

  As shown in FIG. 9 and the like, the side surface of the plug hole wall 27 has a portion 27a facing the exhaust port wall 26 located on the engine front side (upstream side in the flow direction of cooling water) of the pair of exhaust port walls 26, 26. The first flow restriction vertical bead 81 protruding toward the exhaust port wall 26 is formed, and faces the intake port wall 25 located on the rear side of the engine (downstream in the flow direction of the cooling water) of the pair of intake port walls 25. A second flow restricting vertical bead 82 (see FIG. 11) protruding toward the intake port wall 25 is formed in the portion 27b.

  As shown in FIG. 8, the first flow restricting vertical bead 81 is formed so as to extend in a vertical direction relatively long from a low position to a high position of the plug hole wall 27. As shown in FIG. 9, it is configured as an arc cross-sectional shape with a gentle curvature so as to gently throttle the cooling water passage 31a corresponding to the circular shape of the exhaust port wall 26.

  On the other hand, the above-mentioned second flow restriction vertical bead 82 extends to a position lower than the first flow restriction vertical bead 81 and is formed relatively short, as shown in FIG. Similar to the first flow restriction vertical bead 81, the transverse cross-sectional shape is configured as an arc cross-sectional shape with a gentle curvature so as to gently throttle the cooling water passage 31b corresponding to the circular shape of the intake port wall 25. Yes.

  By forming the first flow restricting vertical bead 81 and the second flow restricting vertical bead 82, the total flow rate of the main water jacket 31 is restricted, so that the branch passage 34 (see FIG. 3) branches off. The flow rate of the cooling water flowing out to the exhaust side auxiliary water jacket 33 and the intake side auxiliary water jacket 32 can be increased. Further, since the first flow restricting vertical bead 81 and the second flow restricting vertical bead 82 are formed in the plug hole wall 27, the cooling performance of the plug hole wall 27 can be improved.

  Further, as can be seen from FIG. 8, even if the first flow restriction vertical bead 81 and the second flow restriction vertical bead 82 are formed, the minimum passage cross-sectional area S1 of the exhaust side cooling water passage 31a of the main water jacket 31 is cooled by the intake side cooling. It is larger than the minimum passage cross-sectional area S2 of the water passage 31b.

  For this reason, the flow rate of the exhaust side cooling water passage 31a can be increased, and the cooling performance on the exhaust side can be enhanced while restricting the total flow rate of the main water jacket 31.

  In particular, by providing the first flow restriction vertical bead 81 at this portion, the exhaust side cooling performance can be further enhanced for the following reason.

  That is, as shown in FIG. 9, by providing the first flow restriction vertical bead 81 at this portion, the flow of the cooling water is throttled, and the flow velocity is increased at this portion. Since the cooling passage 35 is opened in the inflow region 31c between the exhaust ports 14 and 14 as described above, the cooling flow is sucked out from the cooling passage 35 by the venturi effect due to the increase in the flow velocity at this portion. The cooling performance on the exhaust side is increased.

  Further, since the first flow restriction vertical bead 81 is formed in a wide range in the vertical direction as described above, the venturi effect can be generated in the wide range in the vertical direction, and the cylinder block 4 side on the diagonally lower side Thus, the function of the cooling passage 35 for sucking the cooling water from can be further improved.

Furthermore, since the first flow restriction vertical bead 81 is provided long in the vertical direction, the lateral width w1 of the exhaust-side cooling water passage 31a is made to be substantially the same across the entire vertical direction. Cooling water flow on the (lower) side can also be generated.
Therefore, the flow on the combustion chamber side is also reliably generated, and the cooling performance on the fuel side can be ensured.

  On the other hand, as described above, the second flow restriction vertical bead 82 is formed in the portion 27b facing the exhaust port wall 26 on the rear side of the engine (downstream in the flow direction of the cooling water). By providing the second flow restriction vertical bead 82 at this portion, the cooling performance on the intake side can be improved for the following reason.

  For example, if the second flow restriction vertical bead 82 is formed in a portion facing the exhaust port wall 26 on the front side of the engine, a part of the flow velocity is increased in the inflow region 31d between the pair of intake ports 13 and 13. Become. However, since the cooling passage 35 between the intake ports 13 and 13 is not provided between the intake ports 13 and 13, there is a possibility that cooling cannot be sufficiently performed by partially increasing the flow velocity.

  That is, as shown by the broken line in FIG. 9, when the flow velocity partially increases, a “vortex” is generated in the inflow region 31d, and the cooling water becomes “stagnation” in the inflow region 31d. The cooling water may not flow properly.

  Therefore, in the present embodiment, by forming the second flow restriction vertical bead 82 at a portion facing the intake port wall 25 on the rear side of the engine, the flow velocity in the inflow region 31d is not changed, and the flow is performed in a rectified state. Therefore, the cooling water flow is appropriately generated to ensure the cooling performance.

  Further, as shown in FIG. 8, by forming the second flow restriction vertical bead 82, the lateral width w2 of the intake side cooling water passage 31b is set to a width that substantially coincides with the entire vertical direction. As a result, like the exhaust-side cooling water passage 31a, the flow on the combustion chamber side (lower side) also occurs reliably, so that the cooling performance on the combustion chamber side can also be enhanced.

  Further, the flow rate of the cooling water in the intake side auxiliary water jacket 32 is increased by reducing the flow rate of the cooling water in the main water jacket 31 by the first flow restriction vertical bead 81 and the second flow restriction vertical bead 82 as described above. Therefore, the cooling performance of the nozzle hole wall 28 provided in contact with the intake side auxiliary water jacket 32 can be enhanced.

  That is, FIG. 12 shows a cross-sectional view taken along the line FF in FIG. 3. As shown in FIG. 12, the intake side auxiliary water jacket 32 is formed so as to surround the nozzle hole wall 28 to which the fuel injection nozzle is mounted. Therefore, the fuel injection nozzle can be cooled by increasing the flow rate of the cooling water to the intake side auxiliary water jacket 32.

  Thus, in this embodiment, since the first flow restriction vertical bead 81 and the second flow restriction vertical bead 82 are provided on the plug hole wall 27 and these beads 81 and 82 are formed at appropriate portions, limited cooling water is provided. It is possible to improve the cooling performance of the cylinder head 5 appropriately and efficiently.

  In particular, since the first flow restriction vertical bead 81 is formed at a portion facing the exhaust port wall 26 located on the front side of the engine (upstream in the flow direction of the cooling water), the function of sucking out the cooling water in the cooling passage 35 can be obtained. The exhaust side cooling performance can be improved.

  Although one embodiment has been described above, the present invention is not limited to this. For example, for the second flow restriction vertical bead 82, the intake port wall on the front side of the engine (upstream in the flow direction of the cooling water). You may form in 25 side. In this case, “stagnation” may occur in the inflow region 31d. However, if the flow rate of the cooling water is large, the possibility of such “stagnation” itself is reduced. However, the cooling performance does not deteriorate.

  Further, the shapes and lengths of the first flow restriction vertical bead 81 and the second flow restriction vertical bead 82 may be appropriately changed according to the flow rate of the cooling water, and are limited to the shape of this embodiment. It is not something.

As described above, in the correspondence between the configuration of the present invention and the above-described embodiment,
The first vertical bead portion of the present invention corresponds to the first flow restriction vertical bead 81 of the embodiment,
Hereinafter, similarly, the second vertical bead portion corresponds to the second flow restriction vertical bead 82,
The spark plug hole wall corresponds to the plug hole wall 27,
The exhaust side passage portion corresponds to the exhaust side cooling water passage 31a,
The intake side passage portion corresponds to the intake side cooling water passage 31b,
The fuel injection valve hole wall corresponds to the nozzle hole wall 28,
The present invention is not limited to the above-described embodiment, but includes an embodiment applied to any engine cylinder head structure.

The schematic diagram of the cooling path | route of the engine which employ | adopted the cylinder head structure of this invention. A partially cutaway plan view of a cylinder head. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. 2 is a cross-sectional view taken along line BB in FIG. The CC sectional view taken on the line of FIG. The bottom view of a cylinder head. (A) Plan view of cylinder block, (b) Plan view of gasket. The DD sectional view taken on the line of FIG. The top view which showed the main water jacket around a plug hole wall. The perspective view around the plug hole wall seen from the exhaust side. The perspective view around the plug hole wall seen from the intake side. FIG. 4 is a cross-sectional view taken along line FF in FIG. 3.

Explanation of symbols

E ... Engine 5 ... Cylinder head 25 ... Intake port wall 26 ... Exhaust port wall 27 ... Plug hole wall (ignition plug hole wall)
31 ... Main water jacket 32 ... Exhaust side auxiliary water jacket 33 ... Intake side auxiliary water jacket 35 ... Cooling passage 81 ... First flow restriction vertical bead (first vertical bead portion)
82 ... Second flow restriction vertical bead (second vertical bead part)

Claims (5)

A valve operating mechanism is configured by two intake valves and two exhaust valves, and a plurality of cylinders having spark plugs arranged at substantially the center are arranged in the row direction. Cooling water is provided around the spark plug hole walls of the cylinders in the cylinder row direction. It has a main water jacket that flows, and an exhaust side auxiliary water jacket in which cooling water flows around the exhaust port wall in the direction of the cylinder row, and the main water jacket and the exhaust side auxiliary water jacket communicate with each other between the cylinders. Engine cylinder head structure,
In the main water jacket, the minimum passage cross-sectional area from the spark plug hole wall to the exhaust port wall side and the minimum passage cross-sectional area from the spark plug hole wall to the intake port wall side are the portions facing the exhaust port wall of the spark plug hole wall. With the first vertical bead portion formed and the second vertical bead portion formed at the portion facing the intake port wall of the spark plug hole wall, the exhaust side is set to be large,
Between the pair of exhaust ports, one end is opened on the lower surface of the cylinder head, and the other end forms a cooling passage that opens facing the spark plug hole wall,
A cylinder head structure for an engine, wherein the first vertical bead portion is formed in a spark plug hole wall facing an exhaust port wall located upstream of a main water jacket in a cooling water flow direction. Of the exhaust side passage portion restricted by the first vertical bead portion and the intake side passage portion restricted by the second vertical bead portion, the exhaust side passage portion is formed higher in the vertical direction,
The cylinder head structure for an engine according to claim 1, wherein the first vertical bead portion is formed longer in the vertical direction than the second vertical bead portion. The cylinder head structure for an engine according to claim 2, wherein the lateral width of the exhaust side passage portion is set to a width that substantially coincides with the entire vertical direction. The engine cylinder head structure according to claim 1, wherein the second vertical bead portion is formed in a spark plug hole wall facing an intake port wall located downstream of the main water jacket in the cooling water flow direction. An intake side sub-water jacket that communicates between the main water jacket and the cylinder is provided below the intake port in the direction of each cylinder.
Between the pair of intake ports and below the intake ports, a fuel injection valve hole wall for mounting a combustion injection valve whose front end faces the combustion chamber is formed,
The engine cylinder head structure according to claim 1, wherein the fuel injection valve hole wall is set in contact with the intake side auxiliary water jacket.

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