JPS633372Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an engine having a combustion chamber partially recessed in the inner wall of the cylinder head.

In engines, especially automobile engines,
In order to purify the exhaust gas, it is desirable that the amount of unburned gas in the exhaust gas be as small as possible.

By the way, engines with a combustion chamber partially recessed in the inner wall of the cylinder head have been attracting attention recently because they can achieve a high compression ratio. Some combustion chambers are equipped with a port and the inner wall of this combustion chamber is made of a heat insulating material.
−97524). According to such a device, when the exhaust gas generated from fuel combustion is discharged from the exhaust port,
Since the combustion of unburned gas is promoted by receiving heat from the inner wall of the combustion chamber made of a heat insulating material around the exhaust valve, the amount of unburned gas in the exhaust gas is reduced. However, since the walls of the combustion chamber around the intake valves are also made of heat insulating material, it is impossible to avoid the intake air that is drawn into the combustion chamber through the intake port from receiving heat from the walls of the combustion chamber. When inhaled into the tank, it expands and reduces its filling efficiency.
In other words, in order to maintain a high compression ratio of intake air in the combustion chamber structure of an engine, it is necessary to increase its volumetric efficiency, but the conventional structure described above has the disadvantage that this is kept small. There is.

This idea was devised in view of the above circumstances, and consists of forming only the combustion chamber wall around the exhaust valve with a heat insulating material, and forming the inner wall around the intake valve with a casting material other than the heat insulating material. It is an object of the present invention to provide a combustion chamber structure for an engine that can reduce the amount of unburned gas and at the same time improve the filling efficiency of intake air.

Next, an embodiment of this invention will be described with reference to the drawings.

In FIGS. 1 and 2, 1 is a cylinder block, 2 is a cylinder head, and a piston 4 is housed in a cylinder 3 constituted by these.

A combustion chamber 5 is recessed in a part of the inner wall of the cylinder head 2, and a spark plug 6 is disposed in the combustion chamber 5, and an exhaust port 8 equipped with an exhaust valve 7 is opened. The entire surface of the inner wall of the combustion chamber 5 except for the opening 8a of the exhaust port 8 is formed of a heat insulating material 9.

In addition to the exhaust port 8 that opens to the combustion chamber 5, an intake port 10 is opened on the inner wall of the cylinder head 2, and an intake valve 11 is provided in the opening 10a.

In such an engine, after a certain stroke, air is taken in from the intake port 10, the mixture is compressed in the combustion chamber 5, ignited by the spark plug 6, fuel is combusted in the combustion chamber 5, and the exhaust port 8 Exhaust is carried out through. In this case, since there is no heat insulating material around the opening 10a of the intake port 10, the phenomenon that the intake air introduced into the cylinder 3 through the intake port 10 is heated is suppressed as much as possible. Therefore, a decrease in filling efficiency due to expansion of intake air is prevented, and thermal efficiency or output is improved.

On the other hand, in the combustion chamber 5, the exhaust valve 7 is surrounded by a heat insulating material 9.
The heat generated from fuel combustion in the insulating material 9
The heat retained by the heat insulating material 9 heats the generated exhaust gas and burns the unburned gas contained therein. Therefore, the amount of unburned gas in the exhaust gas discharged from the exhaust port 8 is reduced.

In this embodiment, the opening 8a of the exhaust port 8 is
Although shown in the figure, it is set at the center of the inner wall of the combustion chamber 5 formed of the heat insulating material 9, but this point is not limited to the illustrated example, and it is set at an eccentric part of the inner wall. Anything is fine. Also,
The number of combustion chambers 5 is not limited to one formed at one location on the inner wall of the cylinder head 2 as in the illustrated example, but may be formed at two or more locations.

With this idea, only the inner wall of the combustion chamber where the exhaust port is opened is made of a heat insulating material, and the wall around the intake port opening is made of ordinary casting material that does not have heat insulating properties. Although the reduction in filling efficiency due to thermal expansion is suppressed as much as possible,
During exhaust, the combustion of unburned gas is promoted and the amount of unburned gas contained in the exhaust gas is reduced.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of this invention;
FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. 2... Cylinder head, 5... Combustion chamber, 8...
Exhaust port, 8a...Exhaust port opening, 9...Insulating material, 10...Intake port, 10a...Intake port opening.

Claims (1)

[Scope of Claim for Utility Model Registration] In an engine comprising a combustion chamber partially recessed in the inner wall of the cylinder head, only the inner wall of the combustion chamber is formed of a heat insulating material,
While opening an exhaust port to the combustion chamber,
A combustion chamber structure for an engine, characterized in that an intake port is opened on an inner wall of a cylinder head other than the combustion chamber.