JP2000320396A - Cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cooling effect by air cooling by arranging an air-cooled passage formed through between an intake port and an exhaust port. SOLUTION: In a cylinder head 1, an air-cooled passage 30 is arranged through between an exhaust port 10 and an intake port 20. Therefore, a clearance is formed between the exhaust part 10 and the intake port 20, so that heat transfer from the exhaust port 10 side to the intake port 20 side is reduced. Consequently, the temperature rise of intake air flowing into a combustion chamber through the intake port 20 can be lowered, and deterioration of engine output due reduction of air density can be prevented. In addition, the air-cooled passage 30 can be formed closer to the combustion chamber side (lower face 2 side), because it is formed through between the exhaust port 10 and the intake port 20. In this way, cooling effect for the combustion chamber and a cylinder part arranged below the lower face 2 of the cylinder head 1 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head for an engine, and more particularly to a cooling structure for a cylinder head.

[0002]

2. Description of the Related Art When an engine reaches a high temperature due to heat generated by a combustion operation, a problem such as knocking occurs, and it is necessary to cool the engine to an appropriate temperature. One of the cooling methods is an air cooling system. For example, in the case of an air-cooled engine mounted on a motor vehicle of a motorcycle, a traveling wind generated by traveling is used, and cooling is performed by receiving the traveling wind on the engine body.

[0003] In the case of an air-cooled engine that cools by using the traveling wind as described above, the temperature around the exhaust port is higher than that around the intake port. In general, the exhaust side is arranged, and the intake side is arranged rearward in the traveling direction.

[0004] Therefore, when the amount of traveling wind is small, such as when traveling at low speed, cooling becomes insufficient and the intake port side may also become hot. When the intake port side reaches a high temperature, the temperature of the intake air flowing into the combustion chamber also increases, and the air density decreases, so that the efficiency of intake air into the combustion chamber decreases and the output of the engine decreases.

Japanese Patent Application Laid-Open No. 64-77738 discloses a cylinder head of an air-cooled engine mounted on a motorcycle.
It is described that a through-hole penetrating through the cylinder head is provided, and the cylinder head is cooled by traveling wind passing through the through-hole.

[0006]

However, according to the above publication, the through hole is provided at a position further above the intake port and the exhaust port provided at the upper part of the combustion chamber.
For this reason, it is difficult to sufficiently cool the combustion chamber and the cylinder portion located below the through hole by the traveling wind passing through the through hole. Also, in this case, when the amount of traveling air passing through the through hole is small, heat is easily transmitted from the exhaust port to the intake port, which may cause a decrease in engine output due to a decrease in intake efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a cylinder head which can improve a cooling effect by air cooling.

[0008]

According to a first aspect of the present invention, there is provided a cylinder head having a through-hole formed as a passage for introducing intake air into a combustion chamber. And a cylinder head having an exhaust port formed as a passage for discharging exhaust gas from the combustion chamber, the cylinder head having an air cooling passage formed so as to pass between the intake port and the exhaust port. Features.

According to this, since the air cooling passage is formed so as to pass through between the intake port and the exhaust port,
The intake port and the exhaust port are separated by an air cooling passage. Therefore, in addition to the effect that the cylinder head can be cooled by the air passing through the air cooling passage, the heat transfer from the exhaust port side to the intake port side can be further reduced. Thus, a rise in temperature around the intake port can be suppressed, and a decrease in output due to a rise in intake air temperature can be prevented.

The cylinder head according to the second aspect of the present invention is characterized in that at least a part of the air cooling passage is formed along the extension direction of the exhaust port. According to this, the air cooling passage is formed so as to pass between the intake port and the exhaust port, and at least a part thereof extends along the extension direction of the exhaust port. Therefore, in addition to the effect of the above-mentioned claim, the exhaust port can be sufficiently cooled. As a result, a rise in the temperature of the cylinder head can be further suppressed, and problems such as knocking due to heat of the cylinder head can be prevented.

In the cylinder head according to the third aspect of the present invention, at least a part of the air cooling passage is formed along the extension direction of the intake port. According to this, the air cooling passage passes between the intake port and the exhaust port, and at least a part thereof is formed to extend along the exhaust port and the intake port, so that the cooling effect of the intake port is also enhanced. be able to.

In the cylinder head according to the present invention, the intake port and the exhaust port are formed so as to extend in directions away from each other, and the air cooling passage is formed at a passage portion between the intake port and the exhaust port. It is characterized by being bent and elongated in shape.

[0013] According to this, since the air cooling passage has a shape that bends into a crank shape at a passage portion between the intake port and the exhaust port, the overall length of the air cooling passage can be lengthened. Therefore, the cooling effect of the combustion chamber and the cylinder can be further improved. Further, the passage shape can be extended more along the exhaust port and the intake port by this passage shape, and the cooling effect can be further improved.

According to a fifth aspect of the present invention, there is provided a cylinder head, wherein one through-opening of the air-cooling passage is formed in front of a vehicle on which the vehicle is mounted in the traveling direction. According to this, the traveling wind generated by the traveling of the vehicle can flow through the through-opening, and the cylinder head can be more actively cooled from the inside. Therefore, the cooling effect can be further improved.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a bottom view of the cylinder head according to the present embodiment, FIG. 2 is a front view, FIG. 3 is a left side view, and FIG. 4 is a rear view. The cylinder head according to the present embodiment is used in a four-stroke engine, and is mounted above a cylinder bore of a cylinder block (not shown).

An engine having such a cylinder head is mounted on a traveling vehicle such as a motorcycle or a four-wheel buggy, and is provided at a position to receive traveling wind during traveling.
FIG. 1 is an explanatory view of the cylinder head 1 as viewed from below. The cylinder head 1 has a lower side in FIG. 1 forward in the vehicle traveling direction, an upper side in FIG. 1 backward in the traveling direction, a left side in FIG. 1 on the left in the traveling direction, and a right side in FIG. 1 on the right in the traveling direction. It is arranged so that it may be located.

The cylinder head 1 has a combustion chamber ceiling 7 recessed substantially at the center of the lower surface 2. The combustion chamber ceiling 7 has a semicircular spherical shape, and a combustion chamber side opening 11 of the exhaust port 10 is formed at a front position in a traveling direction thereof,
An intake port 20 is provided at a position behind the ceiling 7 of the combustion chamber in the traveling direction.
Is formed in the combustion chamber side opening 21.

The combustion chamber side opening 11 of the exhaust port 10 is
The opening is formed in a circular shape whose center is located at a position offset rightward and forward of the cylinder bore center position M with respect to the vehicle traveling direction, and the combustion chamber side opening 21 of the intake port 20 is located at the cylinder bore center position M The opening is formed in a circular shape whose center is located at a position offset to the left and rearward in the vehicle traveling direction.

As shown in FIGS. 2 and 4, a front opening 12 of the exhaust port 10 is formed at a position on the front surface 3 of the cylinder head 1 and at a predetermined height from the lower surface 2. At the rear surface 4 of the head 1 and at a position at a predetermined height from the lower surface 2, a rear opening 22 of the intake port 20 is formed.

The front opening 12 of the exhaust port 10 has an exhaust flange 13 connectable to an exhaust passage (not shown), and the intake port 20 has an intake flange 23 connectable to an intake passage (not shown). It has.

As shown in FIG. 1, when viewed from below, the shape of the exhaust port 10 extends straight forward from the combustion chamber side opening 11 of the exhaust port toward the front in the vehicle traveling direction. When viewed from the side as shown in
A through-hole shape communicating with the front opening 12 of the exhaust port 10 is drawn in a gentle elbow curve.

As shown in FIG. 1, the shape of the port of the intake port 20 extends straight from the combustion chamber side opening 21 of the intake port rearward in the vehicle traveling direction when viewed from below. As seen from the side, when viewed from the side, a gentle elbow curve is drawn to form a through passage communicating with the front opening 22 of the intake port 20.

The cylinder head 1 has an air cooling passage 30 which is a characteristic part of the present invention. Air cooling passage 30
From the front surface 3 to the rear surface 2 at approximately the same height from the lower surface 2
As shown in FIG. 1, it has a crank shape having a part that bends in the left-right direction in the middle.

More specifically, as shown in FIG. 1, the air cooling passage 30 includes an exhaust port side passage portion 31, an intake port side passage portion 32, and a passage portion 33 between the intake and exhaust ports.

Here, the exhaust port side passage portion 31 is
As shown in FIG. 1, a left side position of the exhaust port 10 is drilled rearward in the traveling direction from a front through-opening 34 that opens to the left side of the front opening 12, and as shown in FIG. Elongate. Further, as shown in FIG. 4, the intake port side passage portion 32 is connected to the intake port 2 through a rear through-opening 35 opened to the right of the rear opening 22.
0 is drilled forward in the traveling direction at the right position of FIG.
As shown in (1), it extends to the vicinity of the cylinder bore center position M.

The passage 33 between the intake and exhaust ports
Are the intake port 10 and the exhaust port 2 as shown in FIG.
0, and extends in the left-right direction to communicate between the exhaust port side passage portion 31 and the intake port side passage portion 32.

Thus, the air cooling passage 30 is disposed so as to pass through the side portions of the exhaust port 10 and the intake port 20 and between them. In FIG. 1, reference numeral 9 denotes a chain chamber into which a valve drive chain of a valve mechanism (not shown) provided on the upper surface 6 of the cylinder head 1 is inserted.

Next, the cylinder head 1 having the above configuration will be described.
The function and effect of the method will be described. The cylinder head 1 having the above configuration is provided so that the air cooling passage 30 passes between the exhaust port 10 and the intake port 20 as described above. Therefore, the exhaust port 10 and the intake port 20
Between the exhaust port 10 and the intake port 20 can be reduced.

Therefore, it is possible to suppress a rise in the temperature of the intake air flowing into the combustion chamber through the intake port 20, and to prevent a decrease in the engine output due to a decrease in the air density.

The air cooling passage 30 can be formed at a position closer to the combustion chamber side (the lower surface 2 side) by passing between the exhaust port 10 and the intake port 20. Thereby, the cooling effect of the combustion chamber and the cylinder portion (not shown) arranged below the lower surface 2 of the cylinder head 1 can be improved.

Then, as shown in FIG.
Has an exhaust port side passage portion 31 formed so as to be along the side position of the exhaust port 10 and an intake port side passage portion 32 formed so as to be fed to the side position of the intake port 20. Therefore, the exhaust port 10 and the intake port 2
0 can be cooled more directly.

The air-cooling passage 30 has a passage portion 33 between the intake and exhaust ports extending in the direction intersecting the traveling direction in the middle of the passage, and has a passage shape that is bent in a crank shape as a whole. For this reason, the air cooling passage 30 can be formed longer, and the exhaust port 10 and the intake port 2
0, the air cooling passage 30 can be extended longer, and the cooling effect thereof can be further improved.

The air cooling passage 30 has a front through-opening 34 on the front 3 of the cylinder head and a rear through-opening 35 on the rear 4 of the cylinder head. From the air cooling passage 30 can be positively flown into the air cooling passage 30. Therefore, the cooling effect can be further improved.

It should be noted that the present invention is not limited to the above embodiment, and various changes can be made within the gist of the present invention. For example, in the above embodiment, the air cooling passage 3
Although the shape of 0 has been described as an example of a crank shape penetrating from the front surface 3 to the rear surface 4 of the cylinder head 1, it is not limited to this.

For example, the passage 33 between the intake and exhaust ports
May be formed so as to penetrate to the left surface 5 of the cylinder head 1, or the opening may be closed by a closing member later to form a crank shape as a result. This eliminates the need for a core for forming the passage 33 between the intake and exhaust ports when casting the cylinder head 1.
The labor in the casting process can be saved.

[0036]

As described above, according to the cylinder head of the present invention, the air cooling passage is formed so as to pass through between the intake port and the exhaust port, and is separated by the air cooling passage. Thus, the cylinder head can be cooled by the air passing through the air cooling passage, and the heat transfer from the exhaust port side to the intake port side can be further reduced.
Therefore, a rise in temperature around the intake port can be suppressed, and a decrease in output due to a rise in intake air temperature can be prevented.

The air cooling passage is formed so as to pass between the intake port and the exhaust port and to have at least a part thereof extending along the direction in which the exhaust port extends. Can be sufficiently cooled,
The temperature rise of the cylinder head can be further suppressed,
Problems such as knocking due to heat of the cylinder head can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory bottom view of a cylinder head according to the present embodiment.

FIG. 2 is a front view of a cylinder head.

FIG. 3 is a left side view of the cylinder head.

FIG. 4 is a rear view of the cylinder head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Lower surface 3 Front surface 4 Rear surface 5 Left side surface 7 Combustion chamber ceiling part 10 Exhaust port 20 Intake port 30 Air cooling passage 31 Exhaust port side passage part 32 Intake port side passage part 33 Passage passage part between intake and exhaust ports 34 Front through opening 35 Rear through-opening

Claims (5)

[Claims] 1. A cylinder head having an intake port formed as a passage for introducing intake air into a combustion chamber and an exhaust port formed as a passage for discharging exhaust gas in the combustion chamber. A cylinder head having an air cooling passage formed so as to pass through between the intake port and the exhaust port. 2. The cylinder head according to claim 1, wherein at least a part of the air cooling passage is formed along a direction in which the exhaust port extends. 3. The cylinder head according to claim 2, wherein at least a part of the air cooling passage is formed along a direction in which the intake port extends. 4. The intake port and the exhaust port are formed to extend in directions away from each other, and the air-cooling passage is bent and extended in a crank shape at a passage portion between the intake port and the exhaust port. The cylinder head according to claim 1, wherein: 5. The cylinder head according to claim 1, wherein the air cooling passage has one through-opening formed in a forward direction in a traveling direction of a vehicle mounted on the vehicle.