JPH0313550Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is equipped with a vortex-chamber sub-combustion chamber close to an intake port and an exhaust port, like a cylinder head in a diesel engine, This invention relates to an improvement in a cylinder head comprising a cooling water chamber surrounding an exhaust port and a sub-combustion chamber.

[Conventional technology]

Generally, the swirl chamber type sub-combustion chamber in a diesel engine needs to be maintained at a high temperature to promote vaporization of the injected fuel, so the wall thickness of this sub-combustion chamber relative to the cooling water chamber is considerably thick. It is composed of However, since this auxiliary combustion chamber is formed in a position close to the intake port and exhaust port, the thick part that makes up the auxiliary combustion chamber and the thick part that makes up the intake port and exhaust port are similar to each other. When the valves are cast together, the cooling performance of the valve gap between the intake port and the exhaust port is significantly reduced, and cracks are generated in the valve gap due to heat.

Therefore, Japanese Utility Model Application Publication No. 51-68941 as a prior art discloses that after the cylinder head is cast, the parts between the intake port and exhaust port and the auxiliary combustion chamber are
It is proposed to prevent cracks in the area between the valves by forming a cooling water passage by drilling from the side of the cylinder head.

[The problem that the idea attempts to solve]

However, forming the cooling water passage between the intake port and exhaust port and the auxiliary combustion chamber by drilling from the side of the cylinder head requires a great deal of work. However, there is a problem in that the cost becomes extremely high.

The present invention solves this problem by partially reducing the wall thickness of the sub-combustion chamber relative to the cooling water chamber so as not to impair the flow of cooling water within the cooling water chamber. be.

[Means to solve the problem]

In order to achieve this objective, the present invention integrally forms a sub-combustion chamber boss section that is equipped with a swirl chamber-type sub-combustion chamber inside in a portion close to the intake port and exhaust port, and a cooling water chamber. In a cylinder head formed to surround the outside of the intake port, exhaust port, and sub-combustion chamber boss part, the outer periphery on the intake port and exhaust port side of the outer peripheral surface of the sub-combustion chamber boss part; The surface is formed into a spherical surface whose center is at a point shifted in a direction away from the intake port and the exhaust port from the center of the sub-combustion chamber within the sub-combustion chamber boss portion in plan view.

[Functions and effects of the idea]

In this way, the outer circumferential surface of the auxiliary combustion chamber boss part on the side of the intake port and the exhaust port is positioned closer to the intake port and the exhaust port from the center of the auxiliary combustion chamber within the auxiliary combustion chamber boss part in plan view. By forming a spherical surface centered on a point shifted away from the cylinder head, the sub-combustion chamber boss part and the thick walled parts that constitute the intake port and exhaust port are integrated when the cylinder head is cast. In the meantime, a water channel communicating with the cooling water chamber in the cylinder head can be formed during casting, so between the sub-combustion chamber boss part and the intake port and exhaust port, and between the intake port and the While cooling performance between the exhaust port and the exhaust port can be ensured, the thickness of the sub-combustion chamber boss is only partially thinned, so the temperature of the sub-combustion chamber within the sub-combustion chamber boss is It can reliably maintain high temperatures.

Further, as described above, the outer circumferential surface of the auxiliary combustion chamber boss part on the intake port and exhaust port side is arranged from the center of the auxiliary combustion chamber in the auxiliary combustion chamber boss part to the intake port in a plan view. By forming a spherical surface centered at a point shifted away from the exhaust port, the wall thickness of the sub-combustion chamber boss does not change abruptly, but changes smoothly. Since the temperature distribution in the chamber boss can be averaged, it is possible to prevent cracks from forming in the sub-combustion chamber boss.Furthermore, with the above configuration,
Since the water channel formed between the sub-combustion chamber boss part and the intake port and exhaust port has a smooth shape, the water passage formed between the sub-combustion chamber and the intake port and exhaust port, and between the intake port and exhaust port is smooth. It is possible to further improve the cooling water properties between the two.

Therefore, according to the present invention, unlike the prior art described above, the cooling water passage is not formed by drilling after the cylinder head is cast, but the cooling water passage is inserted into the sub-combustion chamber while the sub-combustion chamber is kept at a high temperature. It is possible to reliably prevent the occurrence of cracks and the occurrence of cracks in the portion between the valves, and it also has the effect of significantly reducing the manufacturing cost of the cylinder head.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a cooling water jacket 7.
The reference numeral 2 indicates a cylinder head fastened to the upper surface of the cylinder block 1 via a gasket 3, and the cylinder head 2 has an intake port 4 and an exhaust port 5 adjacent to each other. At the same time, an auxiliary fuel chamber boss portion 6 having a substantially spherical vortex chamber type auxiliary combustion chamber 6a therein is integrally formed.

A cooling water chamber 8 communicating with the cooling water jacket 7 in the cylinder block 1 is formed in the cylinder head 2 so as to surround the intake port 4, the exhaust port 5, and the auxiliary combustion chamber boss portion 6. There is.

Then, the outer peripheral surface of the auxiliary combustion chamber boss portion 6 on the side of the intake port 4 and the exhaust port 5 is set from the center O of the auxiliary combustion chamber 6a within the auxiliary combustion chamber boss portion 6 in a plan view. By forming a spherical surface with a radius R whose center is O' at a point shifted away from the intake port 4 and exhaust port 5, the wall thickness of the sub-combustion chamber 6a relative to the cooling water chamber 8 can be made smaller than that of the sub-combustion chamber. The wall thickness dimension (T) is not uniform around the entire circumference of the exhaust port 6, but is configured to be partially thinner at locations adjacent to the intake port 4 and exhaust port 5.

That is, when the wall thickness of the sub-combustion chamber 6a relative to the cooling water chamber 8 is set to a uniform wall thickness dimension (T) around the entire circumference of the sub-combustion chamber 6a, as shown by the two-dot chain line in the drawing, , since the thick part forming the sub-combustion chamber 6a is close to the thick part forming the intake port 4 and the exhaust port 5, the cylinder head 2
At the time of casting, the thick portion forming the auxiliary combustion chamber 6 and the thick wall portion forming the intake port 4 and exhaust port 5 are integrated.

On the other hand, as described above, the outer circumferential surface of the auxiliary combustion chamber boss part 6 on the intake port 4 and exhaust port 5 side is If the combustion chamber 6a is formed into a spherical surface with a radius R and a point shifted away from the intake port 4 and exhaust port 5 from the center O of the combustion chamber 6a, a sub-combustion chamber will be formed inside as shown by the solid line in the drawing. a sub-combustion chamber boss portion 6 having a
This makes it possible to form a water channel 9 that smoothly communicates with the cooling water chamber 8 between the thick portions that constitute the intake port 4 and the exhaust port 5 when the cylinder head 2 is cast.

Furthermore, with the above configuration, the water passage 9 between the intake port 4 and the exhaust port 5 has a smooth shape, which improves the flow of cooling water, while also reducing the thickness of the auxiliary combustion chamber boss 6. Since there is no sudden change in thickness, the temperature distribution within the sub-combustion chamber 6a is averaged, and there is an advantage that cracks can be prevented from forming in the sub-combustion chamber boss portion 6.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main parts of an internal combustion engine, and FIG.
FIG. 1... Cylinder block, 2... Cylinder head, 4... Intake port, 5... Exhaust port, 6...
...Sub-combustion chamber boss part, 6a...Sub-combustion chamber, 7...
Cooling water jacket, 8...Cooling water chamber, 9...Waterway.

Claims (1)

[Scope of utility model registration request] In the area close to the intake port and exhaust port,
A sub-combustion chamber boss section with a vortex chamber type sub-combustion chamber inside is integrally formed, while a cooling water chamber is formed to surround the outside of the intake port, exhaust port, and sub-combustion chamber boss section. In the cylinder head, the outer circumferential surface of the auxiliary combustion chamber boss part on the side of the intake port and the exhaust port is arranged such that the intake port extends from the center of the auxiliary combustion chamber within the auxiliary combustion chamber boss part in a plan view. A cylinder head for an internal combustion engine, characterized in that it is formed into a spherical surface centered at a point shifted away from a port and an exhaust port.