JPH0716021Y2 - Cylinder head of air-cooled overhead valve engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cylinder head of an air-cooled overhead valve type engine, and particularly to a thick wall portion in which an intake port, an exhaust port and an ignition plug hole are intensively formed. The present invention relates to a cylinder head of an air-cooled overhead valve type engine, which has improved cooling efficiency.

[Conventional technology]

Conventionally, as a cylinder head of an air-cooled overhead valve type engine,
For example, as shown in FIG. 3, a thick wall portion 3 is provided to cover the upper side of the combustion chamber 2 of the air-cooled overhead valve type engine, and a push rod insertion passage arranged on one side of the thick wall portion 3 with a cooling air passage 4 interposed therebetween. Part 5
Some have and. The upper portion and the lower portion of the thick portion 3 and the push rod insertion portion 5 are connected by an upper wall 6 and a lower wall 7 that partition the upper surface and the lower surface of the cooling air passage 4, respectively.

As shown in FIG. 4, the thick portion 3 has an intake port 8 extending from the lower surface of the cylinder head H (the surface on the paper spine side in the drawing) to the left lateral side in the drawing, and the drawing from the lower surface. An exhaust port 9 which extends through the upper and rear lateral sides, and an ignition plug hole which obliquely penetrates a portion surrounded by the L shape by the intake port 8 and the exhaust port 9 from the upper surface to the substantially center of the combustion chamber 2 on the lower surface. 10 are formed.

The push rod insertion portion 5 is an intake valve push rod insertion portion 5a surrounding the intake valve push rod 11.
And an exhaust valve push rod insertion portion 5b surrounding the exhaust valve push rod 12, between which a laterally branched cooling air passage 13 is formed from the cooling air passage 4 to the lateral side surface of the cylinder head H. ing.

In the cylinder head H of this conventional air-cooled overhead valve engine, the cooling air flows from the lower side to the upper side in FIG. A part of the cooling air that has flowed into 4 flows into the branch cooling air passage 13.

[Problems to be solved by the device]

According to this conventional example, since the cooling air flows only around the thick portion 3 where the heat generated by the combustion is concentrated, there remains dissatisfaction in enhancing the cooling efficiency of the thick portion. In particular, the cooling air stagnates near the spark plug hole 10 formed obliquely from the upper surface to the substantially center of the combustion chamber 2 on the lower surface in the portion surrounded by the intake port 8 and the exhaust port 9 in an L shape, so that the cooling efficiency is improved. The dissatisfaction in raising the level of employment is even greater.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an air-cooled overhead valve for increasing the cooling efficiency of a thick portion in which intake ports, exhaust ports and spark plug holes are intensively formed. To provide a cylinder head of a mold engine.

[Means for Solving the Problems]

The cylinder head of an air-cooled overhead valve engine according to the present invention is, for example, a cylinder head of an air-cooled overhead valve engine as shown in FIGS. 1 and 2, in order to achieve the above object, the following means are provided. Are taking.

That is, for example, as shown in FIG. 1 and FIG. 2, a thick portion 3 that covers the upper side of the combustion chamber 2 of the air-cooled overhead valve engine,
A pair of push rod insertion portions 5a, 5b arranged on one side of the thick portion 3 with a cooling air passage 4 interposed therebetween, and a pair of push rod insertion portions 5a, 5b on the opposite side of the thick portion 3 The intake port 8 extending in the direction, the exhaust port 9 arranged so that the intake port 8 forms an L-shape, and the portion surrounded by the L-shape by the intake port 8 and the exhaust port 9 penetrates from the upper surface to the lower surface. Spark plug hole 10, a branch cooling air passage 13 that separates one push rod insertion portion 5a and the other push rod insertion portion 5b and communicates with the cooling air passage 4, and the cooling air passage to the thick portion 3 4, a high temperature part cooling air passage 14 is provided which communicates with a space surrounded by the intake port 8 and the exhaust port 9 in an L shape through a space between the intake port 8 and the exhaust port 9.

[Action]

According to the present invention, since the cooling air passage 4 for separation is formed between the push rod insertion portions 5a, 5b and the thick portion 3, the push rod insertion portions 5a, 5b and the thick portion 3 are separated from each other. It is possible to suppress the heat conduction of. Also, one push rod insertion part
5a and the other push rod insertion portion 5b form a branch cooling air passage 13 that separates the push rod insertion portion 5a.
The heat conduction between the push rod insertion portion 5b and the push rod insertion portion 5b can be suppressed. Further, since the intake port 8 extends in the thick portion 3 in the direction opposite to the side where the push rod insertion parts 5a, 5b are arranged, the heat of the push rod insertion parts 5a, 5b is conducted to the intake port 8. There is no. Further, a spark plug hole is provided in a space surrounded by the intake port 8 and the exhaust port 9 in an L shape.
Since the spark plug 10 is provided, the spark plug inserted into the spark plug hole 10 is located in the thick portion 3 around the intake port 8 having a relatively low temperature.

Then, a part of the cooling air flowing into the cooling air passage 4 is diverted from the middle of the cooling air passage 4 to the high temperature part cooling air passage 14 and passes between the intake port 8 of the thick portion 3 and the exhaust port 9 to intake air. It is made to flow into the space surrounded by the L-shape by the port 9 and the exhaust port 9, and cools the part between the intake port 8 and the exhaust port 9. Further, the cooling air diverted to the high temperature part cooling air passage 14 is
A flow of cooling air is also formed in the space surrounded by the intake port 8 and the exhaust port 9 in an L shape to cool the spark plug mounted in the spark plug hole 10.

Further, a part of the cooling air that has flowed into the cooling air passage 4 is diverted from the middle of the cooling air passage 4 to the branch cooling air passage 13 to cool the push rod insertion portion 5a and the push rod insertion portion 5b from their surroundings.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

As shown in FIG. 2, the cylinder head 1 is arranged with a thick wall portion 3 covering the upper side of a combustion chamber 2 of a cooling overhead valve type engine and a cooling air passage 4 on one side of the thick wall portion 3. An upper wall 6 and a lower wall 7 that define an upper surface and a lower surface of the cooling air passage 4, respectively, and the upper portion and the lower portion of the thick portion 3 and the push rod insertion portion 5 are provided with a push rod insertion portion 5. Connected by and. In addition, as shown in FIG. 1, the thick portion 3 has a lower surface (in the figure,
By the intake port 8 extending from the bottom surface of the paper) to the left lateral side in the figure, the exhaust port 9 extending from the lower surface to the rear lateral side in the figure, and the intake port 8 and the exhaust port 9. A spark plug hole penetrating diagonally from the upper surface to the center of the combustion chamber 2 in the portion surrounded by the L-shape
10 are formed. Therefore, since the spark plug inserted into the spark plug hole 10 is arranged in the thick portion 3 close to the intake port 8 having a low temperature, overheating of the spark plug can be suppressed. The push rod insertion portion 5 is composed of an intake valve push rod insertion portion 5a that surrounds the intake valve push rod 11 and an exhaust valve push rod insertion portion 5b that surrounds the exhaust valve push rod 12. A laterally branched cooling air passage 13 is formed in the above from the cooling air passage 4 to the lateral side surface of the cylinder head.

Then, in the thick wall portion 3, a cooling air passage 4 is branched, and a lateral outer space of the thick wall portion 3 on the opposite side of the cooling air passage 4 from the cooling air passage 4, that is, between the intake port 8 and the exhaust port 9, , A high temperature part cooling air passage 14 communicating with a space near the spark plug hole 10 surrounded by the intake port 8 and the exhaust port 9 in an L shape.
Is provided.

With respect to the cylinder head 1, the cooling air flows from the front side of the paper to the back side in FIG. 1 and from the lower side to the rear side in FIG. And a part of the cooling air flowing into the cooling air passage 4 is diverted from the middle of the cooling air passage 4 into the branched cooling air passage 13 and the high temperature part cooling air passage 14. Then, the cooling air diverted to the branch cooling air passage 13 cools the intake valve push rod insertion portion 5a and the exhaust valve push rod insertion portion 5b. Also,
The cooling air diverted to the high temperature part cooling air passage 14 is used as the intake port 8
And the exhaust port 9 flows into the space in the vicinity of the spark plug hole 10 surrounded by the L-shape, so that the thick portion 3 is cooled from the inside through the space between the intake port 8 and the exhaust port 9 and the intake port 8 And a flow of cooling air is formed in the space surrounded by the exhaust port 9 in an L shape to form the spark plug hole 10.
It will cool the spark plug attached to. Also,
Since the high temperature part cooling air passage 14 passes between the intake port 8 and the exhaust port 9, the heat transfer amount from the exhaust port 9 to the intake port side is reduced to lower the intake temperature, and the charging efficiency is increased to improve the engine output. Can be increased. Furthermore, since the cooling air that has passed through the high temperature part cooling air passage 14 passes near the ignition plug hole 10, the ignition plug can be efficiently cooled and overheating of the ignition plug can be prevented.

[Effect of device]

As described above, the cylinder head of the air-cooled overhead valve engine of the present invention has the following unique effects.

(A) The push rod insertion portion and the thick wall portion can be individually divided to improve the cooling performance.

A cooling air passage that separates the thick wall portion and the push rod insertion portion is provided, and a branch cooling air passage that separates between one push rod insertion portion and the other push rod insertion portion and communicates with the cooling air passage Is provided, the thick part,
A flow of cooling air can be formed around each of the push rod insertion portions, and the cooling performance can be improved. In addition, since the push rod insertion portion occupies a considerable area in the entire cylinder head, each push rod insertion portion can be cooled, so that an excessive temperature rise of the entire cylinder head can be prevented.

(B) The low temperature near the intake port can be used to cool the spark plug.

By providing an intake port that extends in the direction opposite to the side where the push rod insertion portion is arranged in the thick portion, heat of the push rod insertion portion is not transferred to the intake port, and the intake port and the exhaust port form an L-shape. The spark plug arranged in the portion surrounded by is close to the low temperature intake port in the thick portion, and it is possible to prevent overheating of the spark plug.

(C) The thick part can be cooled from the inside by the high temperature part cooling air passage.

By providing a high temperature part cooling air passage branched from the cooling air passage and communicating between the intake port and the exhaust port to the space surrounded by the intake port and the exhaust port in an L-shape, the thick portion can be removed from the inside. Since it can be cooled, the cooling efficiency of the thick portion can be improved.

(D) The filling efficiency can be improved.

By providing the high temperature part cooling air passage communicating with the space surrounded by the L-shape, the cooling air passes through the high temperature part cooling air passage, so the heat transfer amount from the exhaust port to the intake port side is reduced, and the intake air temperature is reduced. Is reduced. Therefore, the charging efficiency can be increased and the output of the engine can be increased.

(E) The ignition plug can be efficiently cooled by the cooling air flowing in the high temperature part cooling air passage.

By providing the high temperature part cooling air passage communicating with the space surrounded by the L-shape, the cooling air passing through the high temperature part cooling air passage efficiently cools the ignition plug and prevents the ignition plug from becoming overheated. can do.

[Brief description of drawings]

1 and 2 show a cylinder head of an air-cooled overhead valve engine according to an embodiment of the present invention, and FIG. 1 is a line A- in FIG.
FIG. 2 is a front view taken along line A and in FIG. 3 and 4 show a cylinder head of a conventional air-cooled overhead valve type engine, FIG. 3 is a front view, and FIG. 4 is a plan view crossing the line BB in FIG. 1 ... Cylinder head, 2 ... Combustion chamber, 3 ... Thick wall part,
4 ... Cooling air passage, 5a, 5b ... Push rod insertion part, 8
...... Intake port, 9 ...... Exhaust port, 10 ...... Spark plug hole, 13 ...... Branch cooling air passage, 14 ...... High temperature part cooling air passage.

Claims (1)

[Scope of utility model registration request] 1. A thick portion (3) for covering an upper side of a combustion chamber (2) of an air-cooled overhead valve engine, and a cooling air passage (4) arranged on one side of the thick portion (3). A pair of push rod insertion parts (5a) (5b), and an intake port (8) extending in a direction opposite to the side where the push rod insertion parts (5a) (5b) are arranged in the thick part (3); An exhaust port (9) arranged to form an L shape with the intake port (8) and a portion surrounded by the L shape by the intake port (8) and the exhaust port (9) penetrates from the upper surface to the lower surface. Spark plug hole (10)
A branch cooling air passage (13) which separates one push rod insertion portion (5a) from the other push rod insertion portion (5b) and communicates with the cooling air passage (4), and the thick portion (3). ) Is branched from the cooling air passage (4) and communicates with the space surrounded by the L shape by the intake port (8) and the exhaust port (9) through between the intake port (8) and the exhaust port (9). A cylinder head for an air-cooled overhead valve engine, which is provided with a high temperature part cooling air passage (14).