JPH0221570Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an intake and exhaust structure in a four-valve cylinder head of an internal combustion engine.

``Prior Art'' Conventionally, as an intake and exhaust structure for a four-valve cylinder head of an internal combustion engine, for example, those shown in FIGS. 4 to 6 are known. This is because a pair of intake ports 1, 1 and a pair of exhaust ports 2, 2 are located on the lower surface (the fifth
Inside the cylinder head 3 formed on the lower surface in the figure or the surface on the inside of the cylinder in FIG. An intake flow path 4 that opens to the lower side surface, and an exhaust flow path 5 that communicates with the exhaust ports 2 at one end and opens to the side of the cylinder head 3 at the other end are formed.

``Problem to be solved by the invention'' However, in the conventional intake and exhaust structure described above, there is a restriction on the height of the cylinder head (normally, the height is approximately equal to the bore diameter), so the intake flow path is limited. 4
The exhaust flow path 5 and the exhaust flow path 5 are lined up at approximately the same height and extend in the same horizontal direction, resulting in large intake and exhaust resistance and poor engine performance. Also,
A structure is also known in which the intake flow path 4 and the exhaust flow path 5 are extended horizontally in opposite directions to reduce intake and exhaust resistance, but the effect of reducing intake and exhaust resistance is small and is not satisfactory. Ta.

This invention was made in view of the above circumstances,
An object of the present invention is to provide an intake and exhaust structure for a four-valve cylinder head that further reduces intake and exhaust resistance and further improves engine performance.

"Means for Solving the Problems" In order to achieve the above object, the intake and exhaust structure of the present invention has one end communicating with a pair of intake ports, and one end communicating with a pair of intake ports, and the other end communicating with a pair of intake ports. forming a pair of intake passages each opening at the lower surface of the cylinder head, and a first exhaust passage passing horizontally through the cylinder head at a portion inside the cylinder head above the intake passages. A second exhaust passage is formed inside the cylinder head, one end of which communicates with the pair of exhaust ports, the other end of which communicates with the first exhaust flow path and communicates with the outside of the cylinder head.
It has an exhaust flow path formed therein.

"Operation" In the intake/exhaust structure of the present invention, air is taken in through the pair of intake passages, and exhaust is exhausted through the second exhaust passage extending upward and the first exhaust passage extending horizontally. The first exhaust flow path conventionally functions as an exhaust pipe connected to the cylinder head.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

In the figure, 10 is a four-valve type cylinder head having a height of approximately 1.4D when the bore diameter is D, and a pair of intake ports 11a, 11b and a pair of exhaust ports 12a, 12b are formed side by side on the lower surface. ing. In the lower part of the interior of the cylinder head 10, there is a pair of intake passages 13a, each of which has one end communicating with the pair of intake ports 11a and 11b, and the other end of which opens at the lower side surface of the cylinder head 10. ,13
A first exhaust flow path 14 is formed inside the cylinder head 10 above the pair of intake flow paths 13a and 13b and extends horizontally through the cylinder head 10. Inside the cylinder head 10, one end communicates with the pair of exhaust ports 12a, 12b, and the other end communicates with the first exhaust port 12a, 12b.
A second exhaust flow path 15 communicating with the exhaust flow path 14 is formed.

The pair of intake flow passages 13a and 13b have substantially the same cross-sectional area, and extend in a downwardly concave arc shape and along the circumferential direction of the cylinder. The openings on the lower surface of the cylinder head 10 are aligned at the same position in the left-right direction of the cylinder head 10 (left-right direction in FIG. 2). One intake passage 13a is longer than the other intake passage 13b and extends in an arcuate shape with a larger diameter.

Further, the first exhaust flow path 14 is connected to the exhaust port 12.
It has a predetermined circular flow passage cross section larger than that of intake flow passages 13a and 12b, and is located above each other end of the pair of intake passages 13a and 13b, and is used when a plurality of cylinder heads 10 are lined up in a multi-cylinder engine. When disposing, the plurality of cylinder heads 10
(vertical direction in FIG. 2).

Furthermore, one end of the second exhaust flow path 15 communicates with the pair of exhaust ports 12a and 12b, and the other end side is diagonally connected to the first exhaust flow path 14 from the side and is connected to the communication path 16. Cylinder head 10
The exhaust flow path 5 is opened at the upper surface of the exhaust flow path, and extends in a gentle oblique direction, and has a larger cross-sectional area than the conventional exhaust flow path 5 shown in FIG.

In addition, in the figure, 17 is an intake valve, and 18 is a valve spring. In addition, 19 is a valve pusher fitting, which is attached to the cylinder head 1.
The guide portion 20 is slidably fitted into a guide hole of a guide portion 20 that is integrally formed in the upper portion of the guide portion 20 by casting.

When the cylinder heads 10 are used, for example, in a vertical in-line eight-cylinder diesel engine, eight cylinder heads 10 are arranged in a line as shown in FIG. And each intake flow path 13a, 13
While an intake pipe (not shown) is connected to the open end of b, for example, as shown in the figure, the first exhaust passages 14 of every two cylinders are communicated with each other, and one cylinder head of each of the two cylinders is connected to the The exhaust pipes 21 are connected to the open ends of the ten communicating passages 16, and the remaining first exhaust flow passages 14 and the open ends of the communicating passages 16 are closed by closing members.

In this state, intake air enters the pair of intake channels 13a, 13b from an intake pipe (not shown), and as the intake valves 17, 17 operate, the intake ports 11a, 1
It is ejected from 1b into the cylinder. In addition, the exhaust inside each cylinder is discharged from the exhaust port 12 with the operation of the exhaust valve.
a, 12b into the second exhaust flow path 15 and directly flows out from the communication path 16 to the exhaust pipe 21, or enters the first exhaust flow path 14 of the adjacent cylinder head 10 through the first exhaust flow path 14 and enters the communication path. 16 and flows out into the exhaust pipe 21.

Here, in the above intake and exhaust structure, two intake passages 13a and 13b are formed in the cylinder head 10, and these intake passages 13a and 13b extend in a gentle arc shape, compared to the conventional one. As a result, the flow path area increases, pressure loss at the bending portion decreases, and intake resistance decreases. Further, since each of the intake air passages 13a and 13b extends along the circumferential direction of the cylinder, the intake air flows in the circumferential direction of the cylinder, generating a strong swirl. Furthermore, the second exhaust flow path 15 has a larger cross-sectional area than the conventional one and extends upward while being gently inclined, so that the exhaust resistance is small. Furthermore, conventionally, in the above-mentioned vertical in-line 8 cylinder diesel engine, a long exhaust pipe was connected to the cylinder head.
4 is formed, and this first exhaust flow path 14 functions as a conventional exhaust pipe. For this reason, the exhaust pipe 21
The length of the exhaust gas is shortened, and the overall exhaust resistance is significantly reduced.

"Effects of the Invention" As explained above, the intake and exhaust structure of the four-valve cylinder head of the present invention makes the height of the cylinder head higher than that of the conventional one, thereby forming a pair of intake passages, and Since the two exhaust channels are provided to extend upward and the first exhaust channel is integrated, which functions as a conventional exhaust pipe, intake resistance and exhaust resistance are further reduced, improving engine performance. Moreover, it has the effect of making the exhaust pipe easier to install.

[Brief explanation of drawings]

Figures 1 to 3 show an embodiment of the present invention, in which Figure 1 is a sectional view from the side, Figure 2 is a sectional view from below, and Figure 3 is an embodiment of the present invention applied to an 8-cylinder engine. In addition, FIGS. 4 to 6 show conventional examples, and FIG. 4 is a sectional view from below.
FIG. 5 is a side sectional view showing the exhaust flow path, and FIG. 6 is a side sectional view showing the intake flow path. 10...4-valve cylinder head, 11a, 11
b...Intake port, 12a, 12b...Exhaust port, 13
a, 13b...Intake flow path, 14...First exhaust flow path, 15...Second exhaust flow path.

Claims (1)

[Scope of utility model registration request] In a four-valve cylinder head in which a pair of intake ports and a pair of exhaust ports are formed on the lower surface, each one end communicates with the pair of intake ports, and each other end communicates with the pair of intake ports in the lower part of the interior of the cylinder head. A pair of intake passages are formed on the lower surface of the cylinder head, and a first exhaust passage is provided inside the cylinder head above the intake passages, and a first exhaust passage passes through the cylinder head in a horizontal direction. A passage is formed inside the cylinder head, and one end communicates with the pair of exhaust ports, and the other end communicates with the first exhaust port.
An intake and exhaust structure for a four-valve cylinder head, characterized in that a second exhaust flow path is formed which communicates with the exhaust flow path and communicates with the outside of the cylinder head.