JP7200863B2 - cylinder head - Google Patents

Description

The present invention relates to cylinder heads.

The internal combustion engine disclosed in Patent Document 1 includes a cylinder block in which cylinders are partitioned. A cylinder head is arranged above the cylinder block. A combustion chamber is defined at a position facing the cylinder in the cylinder head. A pair of exhaust ports extend from the combustion chamber. Water jackets through which cooling water flows are partitioned above and below the exhaust port in the cylinder head.

JP-A-2002-070642

In the technique disclosed in Patent Document 1, air may enter the water jacket. When air stays at a specific location due to the uneven shape or arrangement of the water jacket, cooling by cooling water is hindered at the location where the air stays. Here, since the air is directed upward, the air tends to stay in the upper portion of the water jacket. If the air stays in the upper portion of the lower water jacket, the cooling efficiency of the exhaust port located above the lower water jacket is reduced. Under these circumstances, it is necessary to discharge the air from the lower water jacket so that the air does not stay in the lower water jacket.

A cylinder head for solving the above-mentioned problems comprises a pair of exhaust ports for discharging exhaust from one combustion chamber, a port collecting portion where the pair of exhaust ports are collected, and a water jacket through which cooling water flows. is a cylinder head partitioned inside, wherein the water jacket comprises an upper water jacket and a lower water jacket positioned below the upper water jacket, the lower water jacket includes a first flow passage portion positioned below the port collecting portion, and a second flow passage portion projecting upward from the first flow passage portion and positioned between the pair of exhaust ports. A communication hole extending to the upper water jacket extends from a wall surface defining the protruding end of the second flow path portion.

In the above configuration, the second channel portion of the lower water jacket is located between the pair of exhaust ports so as to cool the space between the exhaust ports. The second channel portion has a shape that protrudes upward with respect to the first channel portion. Here, the air mixed in the cooling water tries to move upward. Therefore, when air enters the second flow path, the air tends to stay in the upper part of the second flow path.

In this regard, in the above configuration, the second flow path portion communicates with the upper water jacket through the communication hole. Therefore, when air enters the second flow path, the air is discharged from the second flow path to the upper water jacket. Therefore, it is possible to prevent the cooling efficiency between the exhaust ports from deteriorating due to the air remaining in the second flow path portion.

1 is a cross-sectional view schematically showing the configuration of an internal combustion engine; FIG. FIG. 2 is a cross-sectional view in the direction of arrow 2-2 in FIG. 1; FIG. 2 is a cross-sectional view in the direction of arrows 3-3 in FIG. 1;

An embodiment of the cylinder head will be described below with reference to the drawings. In this specification, the vertical direction of the internal combustion engine is described as being the direction in which the cylinder head is superimposed on a cylinder block, which will be described later, that is, the vertical direction in FIG.

First, the schematic configuration of the internal combustion engine will be described. As shown in FIG. 1, an internal combustion engine 10 includes a cylinder block 12 that is generally rectangular parallelepiped. A cylindrical cylinder 14 is defined in the cylinder block 12 . The cylinder 14 is open to the upper surface of the cylinder block 12 . Although four cylinders 14 are provided in the cylinder block 12, only one is shown in FIG. 1 and only two are shown in FIG. The four cylinders 14 are arranged linearly in the longitudinal direction of the cylinder block 12 .

As shown in FIG. 1, a piston 16 is accommodated in the cylinder 14 so as to be able to reciprocate. Although not shown, the piston 16 is connected to the crankshaft via a connecting rod.

A generally rectangular parallelepiped cylinder head 20 is fixed to the upper surface of the cylinder block 12 . A concave portion 21 is recessed at a position facing the cylinder 14 on the lower surface of the cylinder head 20 . A recess 21 is provided for each cylinder 14 . A combustion chamber 22 for burning fuel is defined by the inner surface of the recess 21 , the inner surface of the cylinder 14 and the upper surface of the piston 16 . Four such combustion chambers 22 are arranged side by side in the direction in which the cylinders 14 are arranged.

An intake port 24 for supplying a mixture of intake air and fuel to a combustion chamber 22 is defined in the cylinder head 20 . Two intake ports 24 are provided for each combustion chamber 22 , that is, one pair is provided for each combustion chamber 22 . When the width direction of the cylinder head 20 is defined as the direction perpendicular to both the direction in which the combustion chambers 22 are arranged in the cylinder head 20 and the vertical direction, the pair of intake ports 24 extend from the combustion chamber 22 to one side of the cylinder head 20 in the width direction. side (hereinafter referred to as the intake side).

On the intake side of the pair of intake ports 24 in the cylinder head 20, an intake port assembly portion 25 for gathering the pair of intake ports 24 is defined. That is, the ends of the pair of intake ports 24 opposite to the side communicating with the combustion chamber 22 communicate with the intake port assembly 25 . The intake port gathering portion 25 is provided for each combustion chamber 22 . The intake port assembly 25 opens on the side surface of the cylinder head 20 on the intake side.

An exhaust port 26 for supplying exhaust gas from the combustion chamber 22 is defined on the opposite side of the intake port 24 across the combustion chamber 22 in the cylinder head 20 . As shown in FIG. 3 , two exhaust ports 26 are provided for each combustion chamber 22 , that is, one pair is provided for each combustion chamber 22 . The pair of exhaust ports 26 extends from the combustion chamber 22 toward the other widthwise side of the cylinder head 20 (hereinafter referred to as the exhaust side). The pair of exhaust ports 26 are arranged side by side in the direction in which the combustion chambers 22 are arranged. The ends of the pair of exhaust ports 26 on the exhaust side are closer to each other toward the exhaust side, and are arranged in a substantially V shape when the cylinder head 20 is viewed from above.

On the exhaust side of the pair of exhaust ports 26 in the cylinder head 20, an exhaust port gathering portion 27 that gathers the pair of exhaust ports 26 is defined. That is, the ends of the pair of exhaust ports 26 opposite to the side communicating with the combustion chamber 22 communicate with the exhaust port assembly 27 . The exhaust port gathering portion 27 is provided for each combustion chamber 22 . The four exhaust port collecting portions 27 are connected to each other on the downstream side of the exhaust gas to form a continuous confluence passage 28 . The confluence passage 28 opens on the side surface of the cylinder head 20 on the exhaust side.

As shown in FIG. 1 , a plug hole 29 is recessed above the combustion chamber 22 in the cylinder head 20 . A plug hole 29 is provided for each combustion chamber 22 . The plug holes 29 are positioned between the pair of intake ports 24 and the pair of exhaust ports 26 . A spark plug 30 for igniting the fuel is attached to the plug hole 29 . A tip of the ignition plug 30 is positioned within the combustion chamber 22 .

As shown in FIG. 3 , a bolt insertion hole 23 extends vertically through the cylinder head 20 . Five bolt insertion holes 23 are provided, but only two are shown in FIG. The five bolt insertion holes 23 are arranged side by side on a straight line extending in the direction in which the combustion chambers 22 are arranged. The five bolt insertion holes 23 are located on the exhaust side of the combustion chamber 22 and on the intake side of the exhaust port assembly 27 in the width direction of the cylinder head 20 . Three of the five bolt insertion holes 23 are located between exhaust ports 26 extending from adjacent combustion chambers 22 . The remaining two are located on one side and the other side of all the exhaust ports 26 in the direction in which the combustion chambers 22 are arranged. Although not shown, bolts for fastening the cylinder head 20 to the cylinder block 12 are inserted through the bolt insertion holes 23 .

Next, the cooling structure of the cylinder head 20 will be described. A water jacket through which cooling water flows is defined inside the cylinder head 20 . Water jackets are provided at various portions of the cylinder head 20 that require cooling. The structure of the water jacket for the second combustion chamber 22 (hereinafter referred to as the second combustion chamber 22B) counted from the combustion chamber 22 located on the farthest side in the direction in which the combustion chambers 22 are arranged will be described below. do.

As shown in FIG. 1 , a first water jacket 50 is defined around the second combustion chamber 22B in the cylinder head 20 . The first water jacket 50 is provided on the intake side and the exhaust side across the second combustion chamber 22B. The first water jacket 50 located on the intake side extends from a portion between the pair of intake ports 24 near the second combustion chamber 22B toward the center of the second combustion chamber 22B. The first water jacket 50 located on the exhaust side extends from a portion near the second combustion chamber 22B between the pair of exhaust ports 26 toward the center of the second combustion chamber 22B. Although not shown, the first water jacket 50 located on the intake side and the first water jacket located on the exhaust side are connected to each other by an annular flow path surrounding the spark plug 30 .

A second water jacket 60 is defined in the cylinder head 20 around the pair of exhaust ports 26 extending from the second combustion chamber 22B and the exhaust port gathering portion 27 where the exhaust ports 26 join. The second water jacket 60 can be roughly divided into an upper water jacket 70 and a lower water jacket 80 .

Most of the upper water jacket 70 is located above the pair of exhaust ports 26 extending from the second combustion chamber 22B. The upper water jacket 70 extends in the width direction of the cylinder head 20 from a portion of the pair of exhaust ports 26 closer to the second combustion chamber 22B to an exhaust-side end of the exhaust port collecting portion 27 . As shown in FIG. 2, of the pair of exhaust ports 26, the one located on one side with respect to the direction in which the combustion chambers 22 are arranged is the one side exhaust port 26A, and the one located on the other side is the other side exhaust port. 26B, the upper water jacket 70 extends from one side of the one side exhaust port 26A to the other side of the other side exhaust port 26B in the direction in which the combustion chambers 22 are arranged. As a result, when the cylinder head 20 is viewed from above, the upper water jacket 70 overlaps the pair of exhaust ports 26 and the exhaust port collecting portion 27 associated with the second combustion chamber 22B.

As shown in FIG. 1, the lower water jacket 80 has a first flow passage portion 82 positioned below the exhaust port collecting portion 27 associated with the second combustion chamber 22B. In the width direction of the cylinder head 20, the first flow path portion 82 extends from a portion of the pair of exhaust ports 26 extending from the second combustion chamber 22B near the exhaust port collecting portion 27 to an exhaust side portion of the exhaust port collecting portion 27. It has reached the end. As shown in FIG. 2, the first flow path portion 82 extends from one side of the one side exhaust port 26A to the other side of the other side exhaust port 26B in the direction in which the combustion chambers 22 are arranged. Therefore, when the cylinder head 20 is viewed from above, the first flow path portion 82 is arranged at a position overlapping the pair of exhaust ports 26 and the exhaust port collecting portion 27 relating to the second combustion chamber 22B. In FIGS. 1 and 2 , the upper delimiting portion of the first flow path portion 82 is virtually indicated by a one-dot chain line.

As shown in FIG. 1 , a second flow path portion 84 protrudes upward from the first flow path portion 82 . As shown in FIG. 3, when the cylinder head 20 is viewed from above, the second flow passage portion 84 is positioned between the crotch portions 20P of the pair of exhaust ports 26, that is, between the pair of exhaust ports 26. . Further, the second flow path portion 84 is arranged closer to the exhaust side end of the crotch portion 20P. In this embodiment, when the cylinder head 20 is viewed from above, the second flow path portion 84 is positioned outside the opening edge of the recess 21 and on the exhaust side of the bolt insertion hole 23 .

As described above, when the cylinder head 20 is viewed from above, the first flow path portion 82 is arranged at a position overlapping the pair of the exhaust port 26 and the exhaust port collecting portion 27 . That is, when the cylinder head 20 is viewed from above, the area of the second flow path portion 84 is smaller than the area of the first flow path portion 82 . As a result, as shown in FIGS. 1 and 2 , the second flow path portion 84 has a shape projecting upward with respect to the first flow path portion 82 . A wall surface 84 a that defines the protruding end of the second flow path portion 84 and corresponds to the tip of the projection is positioned between the pair of exhaust ports 26 .

As shown in FIG. 3, the cross-sectional shape of the second flow path portion 84 when the cylinder head is viewed from above is generally triangular. One side of this triangle extends along the wall surface that defines the one-side exhaust port 26A and extends to the vicinity of the joint 20S between the wall surface that defines the one-side exhaust port 26A and the wall surface that defines the other-side exhaust port 26B. . Another side of the triangle extends along the wall surface defining the other side exhaust port 26B and near the joint 20S. In this manner, the second flow path portion 84 is shaped so as to extend into the width direction of the cylinder head 20 up to just before the joint 20S.

As shown in FIG. 2 , a third channel portion 86 protrudes upward from the first channel portion 82 . Two third channel portions 86 are provided. One of the two third channel portions 86 is located on the opposite side of the second channel portion 84 across the one-side exhaust port 26A. As shown in FIG. 3, the third flow path portion 86 is located between the one side exhaust port 26A and the exhaust port 26 extending from the combustion chamber 22 on the farthest side with respect to the direction in which the combustion chambers 22 are arranged. ing. As shown in FIG. 2, the one-side exhaust port 26A is surrounded from below by the third channel portion 86, the first channel portion 82, and the second channel portion 84. As shown in FIG. In the cross section of the cylinder head 20 viewed from the exhaust side, the wall surfaces of the third channel portion 86, the first channel portion 82, and the second channel portion 84 facing the one-side exhaust port 26A are It is U-shaped.

The other of the two third flow path portions 86 is provided substantially symmetrically with the one third flow path portion 86 with the second flow path portion 84 interposed therebetween. In other words, the other third channel portion 86 is located on the opposite side of the second channel portion 84 across the other side exhaust port 26B. The other side exhaust port 26B is surrounded from below by the third channel portion 86, the first channel portion 82, and the second channel portion 84. As shown in FIG.

As shown in FIG. 1 , the inflow channel portion 81 extends downward from the first channel portion 82 . The inflow channel portion 81 opens to the lower surface of the cylinder head 20 . The inflow channel portion 81 is positioned at the intake-side end of the first channel portion 82 in the width direction of the cylinder head 20 . Although not shown, the inside of the cylinder block 12 is partitioned with a water jacket through which cooling water flows. The inflow passage portion 81 described above communicates with the water jacket of the cylinder block 12 through an opening in the lower surface of the cylinder head 20 .

As shown in FIG. 1, the wall surface 84a that defines the protruding end of the second channel portion 84 is flat. A communication hole 90 extends upward from the wall surface 84a. The communication hole 90 reaches the upper water jacket 70 . Through this communication hole 90 , the second flow path portion 84 and the upper water jacket 70 are communicated with each other. The communication hole 90 is located at the intake-side end of the wall surface 84 a that defines the projecting end of the second flow path portion 84 in the width direction of the cylinder head 20 . The passage cross-sectional area of the communication hole 90 is smaller than the area of the wall surface 84 a that defines the projecting end of the second flow path portion 84 . Further, when the cylinder head 20 is viewed from above, the communication hole 90 is positioned within the range of the inflow passage portion 81 . The communication hole 90 is drilled from below through the inflow channel portion 81 and extends linearly.

Next, the flow of cooling water in the second water jacket 60 will be described as an operation of this embodiment.
Cooling water is supplied from the water jacket of the cylinder block 12 to the second water jacket 60 through the inflow passage portion 81 . Cooling water is supplied from the inflow channel portion 81 to the first channel portion 82 of the lower water jacket 80, and from the first channel portion 82 to the second channel portion 84 and the third channel portion 86. . The cooling water supplied to the second flow path portion 84 reaches the upper water jacket 70 via the communication hole 90 .

Next, the effects of this embodiment will be described.
(1) The crotch portion 20</b>P of the pair of exhaust ports 26 tends to become hot due to the heat from both of the pair of exhaust ports 26 . A wall portion in a high-temperature environment is likely to deteriorate, and cracks and the like are likely to occur. Therefore, in the above configuration, the second flow path portion 84 of the lower water jacket 80 is arranged at the crotch portion 20P so as to cool the wall portions located at the crotch portion 20P of the pair of exhaust ports 26. .

Here, air may enter the lower water jacket 80 . If this air stays at a specific location in the lower water jacket 80, cooling by the cooling water will be hindered at that location. Since the air tends to move upward, when the air enters the second flow passage portion 84 having a convex shape, the air tends to stay in the upper portion of the second flow passage portion 84 . If the communication hole 90 does not exist, once the air stays in the upper portion of the second flow path portion 84, it is difficult for the air to be discharged from the second flow path portion 84 having a convex shape.

In this regard, in the above configuration, air is discharged from the second flow path portion 84 to the upper water jacket 70 via the communication hole 90 . Therefore, it is possible to prevent the cooling efficiency of the crotch portion 20</b>P of the pair of exhaust ports 26 from deteriorating due to the air remaining in the second flow path portion 84 .

(2) As described above, since the second flow path portion 84 is convex upward, it is difficult for the cooling water to be supplied and discharged. Therefore, if the circulation of the cooling water is not promoted in the second flow passage portion 84, the cooling water stays in the second flow passage portion 84 in a state where the temperature is raised by the heat from the surrounding wall portion. The warmed cooling water becomes lighter and stays in the upper portion of the second flow path portion 84 , so that the warmed cooling water is less likely to be discharged from the convex second flow path portion 84 . If this situation continues, the situation where the cooling function of the second flow path portion 84 is not exhibited will continue, which is not preferable. Therefore, it is desired to promote the circulation of cooling water in the second flow path portion 84 .

In this regard, in the above configuration, the communication hole 90 communicates between the second flow path portion 84 and the upper water jacket 70 . As a result, the cooling water flows from the second flow path portion 84 to the upper water jacket 70, and the circulation of the cooling water in the second flow path portion 84 is promoted. Therefore, the crotch portions 20</b>P of the pair of exhaust ports 26 can be efficiently cooled by the cooling water in the second flow path portion 84 .

(3) At the exhaust-side end of the crotch portion 20P of the pair of exhaust ports 26, in addition to the fact that the pair of exhaust ports 26 are arranged close to each other, the exhaust from both of the pair of exhaust ports 26 The temperature is extremely high due to the heat from the exhaust port assembly portion 27 where the . Therefore, it is desired that the exhaust-side ends of the crotch portions 20P of the pair of exhaust ports 26 be cooled particularly efficiently.

In the above configuration, the second flow path portion 84 is arranged closer to the exhaust side end of the crotch portion 20</b>P of the pair of exhaust ports 26 . In addition, the second flow path portion 84 is shaped so as to enter just before the joint 20S of the wall surfaces that partition the pair of exhaust ports 26 . Since the cooling water flows through the second flow path portion 84, the exhaust-side ends of the crotch portions 20P of the pair of exhaust ports 26 can be efficiently cooled.

(4) As a method for producing the communication hole 90 that communicates the upper water jacket 70 and the lower water jacket 80, the communication hole is also cast together with the upper water jacket 70 and the lower water jacket 80 when casting the cylinder head 20. can be considered. In this case, in addition to the cores that form the upper water jacket 70 and the lower water jacket 80, the cores that form the communication holes are also shaped. At this time, the core forming the communication hole is required to have supporting rigidity for supporting the upper water jacket 70 and the lower water jacket 80 therebetween. There are restrictions on the cross-sectional area, position, and number of cores, and the design and shaping of the core takes a considerable amount of time and effort.

In this regard, in the above configuration, the communication hole 90 is formed by drilling. Therefore, the upper water jacket 70 and the lower water jacket 80 are prepared in advance, and holes are only drilled later, which facilitates the preparation.

In addition, this embodiment can be changed and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- When the internal combustion engine 10 is mounted on the vehicle, the vertical direction of the internal combustion engine 10 may be tilted with respect to the vertical direction of the vehicle. Even if the vertical direction of the internal combustion engine 10 is slightly tilted with respect to the vertical direction of the vehicle, if the cylinder head 20 is positioned generally above the cylinder block 12 with respect to the vertical direction of the vehicle, the communication hole is maintained. 90 extends upward from the second flow path portion 84 . Therefore, the structure of the above-described embodiment that discharges air from the second flow path portion 84 to the upper water jacket 70 is established.

- The wall surface 84a that defines the projecting end of the second flow path portion 84 may not be flat, and may be curved, for example. In addition, it is preferable to connect the communication hole 90 to a portion of the wall surface 84a of the second flow path portion 84 that is located at the uppermost position when the internal combustion engine 10 is mounted on the vehicle.

- The cross-sectional shape of the second flow path portion 84 when the cylinder head 20 is viewed from above is not limited to the example of the above embodiment. Regardless of the cross-sectional shape of the second channel portion 84, if the second channel portion 84 exists in the crotch portion 20P of the pair of exhaust ports 26, the crotch portion 20P can be cooled. can be done. The cross-sectional shape of the second flow path portion 84 may be elliptical, for example.

- The extension range of the second flow path portion 84 in the width direction of the cylinder head 20 is not limited to the example of the above embodiment. With respect to the width direction of the cylinder head 20 , the second flow path portion 84 extends from the exhaust side of the bolt insertion hole 23 to the intake side of the bolt insertion hole 23 , or extends from the exhaust side of the bolt insertion hole 23 to the recess 21 . It may extend to the inner side of the opening edge of the.

- The arrangement of the second flow path portion 84 in the width direction of the cylinder head 20 is not limited to the example of the above embodiment. The entire area of the second flow path portion 84 may be arranged closer to the intake side than the bolt insertion holes 23 in the width direction of the cylinder head 20 .

- The 3rd flow-path part 86 is not essential.
- The arrangement and extension direction of the inflow channel portion 81 are not limited to the example of the above-described embodiment. For example, depending on the position of the water jacket of the cylinder block 12 , the inflow channel portion 81 may be positioned in the center of the first channel portion 82 with respect to the width direction of the cylinder head 20 . Also, the inflow passage portion 81 does not have to be connected to the water jacket of the cylinder block 12 . For example, the inflow channel portion 81 may be configured as a channel that connects the first channel portion 82 and the first water jacket 50 . The cooling water flow path may be configured such that the cooling water flows from the first water jacket 50 to the first flow path portion 82 via the inflow flow path portion 81 .

- The communication hole 90 does not have to extend linearly, for example, it may be bent in the middle. If the communication hole 90 extends upward as a whole from the second flow path part 84 , air will reach the upper water jacket 70 from the second flow path part 84 through the communication hole 90 .

- It is not essential to process the communication hole 90 with a drill. That is, the communicating hole 90 may be produced by casting. In this case, the effect of (4) above cannot be obtained, but the effects of (1) to (3) above can be obtained.

- The passage cross-sectional area of the communicating hole 90 and the area of the wall surface 84a that defines the projecting end of the second flow path portion 84 may be approximately the same.
- The position where the communicating hole 90 is connected to the wall surface 84a that defines the projecting end of the second flow path portion 84 is not limited to the example of the above-described embodiment. For example, the communication hole 90 may be positioned in the center of the wall surface 84a with respect to the width direction of the cylinder head 20 . As described above, it is preferable to connect the communication hole 90 to the uppermost portion of the wall surface 84a of the second flow path portion 84 when the internal combustion engine 10 is mounted on the vehicle.

- The structures of the first water jacket 50 and the second water jacket 60 associated with the second combustion chamber 22B may be applied as water jackets associated with other combustion chambers.
- The overall configuration of the internal combustion engine 10 is not limited to the example of the above embodiment. For example, the number of cylinders may be changed. A fuel injection valve may be attached to the combustion chamber 22 to directly inject fuel into the combustion chamber 22 .

Reference Signs List 10 Internal combustion engine 20 Cylinder head 22 Combustion chamber 26 Exhaust port 27 Exhaust port assembly 60 Second water jacket 70 Upper water jacket 80 Lower water jacket 82 Second 1 channel part, 84... 2nd channel part, 90... Communication hole.

Claims (1)

a pair of exhaust ports for exhausting exhaust from one combustion chamber;
a port assembly portion in which the pair of exhaust ports are assembled together on the downstream side of the exhaust ports ;
A water jacket through which cooling water flows is a cylinder head partitioned inside,
The water jacket comprises an upper water jacket and a lower water jacket positioned below the upper water jacket,
the lower water jacket includes a first flow path portion located below the port collecting portion;
a second flow path projecting upward from the first flow path and positioned between the pair of exhaust ports;
A communication hole extending to the upper water jacket extends from a wall surface defining the projecting end of the second flow path portion.

Images