JPH063171Y2 - Cylinder head gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a cylinder head gasket of a multi-cylinder engine.

(Prior Art) In a multi-cylinder engine, since the water temperature distribution of the cooling water for cooling each cylinder is not uniform, a temperature difference occurs between the cylinders, and the concentration of the air-fuel mixture distributed to each cylinder is the length of the branch pipe. Due to such effects, there is a problem that knocking is likely to occur in a specific cylinder. To prevent knocking, the compression ratio may be lowered or the ignition timing may be shifted.

By the way, conventional multi-cylinder engines are generally designed so that the compression ratios of all the cylinders are the same. It is necessary to lower the compression ratio or shift the ignition timing from the optimum ignition timing.
There was a problem that the engine output was significantly reduced.
As a means for solving such a problem, Japanese Patent Laid-Open No. 60-842
In Japanese Patent Publication No. 9, a prior art is proposed in which the compression ratio of each cylinder is made different depending on the respective combustion mode.

(Problems to be Solved by the Invention) The present invention is based on the idea of the above-mentioned prior art, but when embodying this, it is advantageous in that the structure is simple, the cost is low, and fine adjustment is performed. The purpose is to provide means.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a cylinder head gasket in which a plurality of cylinder bore openings are arranged side by side. It is characterized in that it is made larger than the opening area of the cylinder bore opening corresponding to the difficult cylinder.

(Operation) According to the above configuration, since the volume of the cylinder bore opening corresponding to the cylinder in which knocking easily occurs is large and the volume of the combustion chamber is large, it is possible to reduce the compression ratio and prevent knocking.

Moreover, a cylinder head gasket having a plurality of cylinder bore openings with different opening areas is manufactured by forming punched holes with slightly different shape dimensions on the gasket substrate and installing grommets with different opening areas in the punched holes. Since it is sufficient, the structure is simple and the cost can be reduced.

Further, the shape and size of the cylinder bore opening can be arbitrarily selected, and the volume of the opening can be slightly changed according to the opening area.Therefore, the volume of the combustion chamber between the cylinders can be increased or decreased according to the difficulty of knocking. The compression ratio can be finely adjusted.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

Cylinder head gasket A shown in FIGS. 1 to 3
Is used in a water-cooled four-cylinder engine in which cylinders 4a, 4b, 4c, 4d having the same inner diameter d are arranged in parallel from the upstream side to the downstream side of cooling water. In the engine, the combustion state is slightly different between the cylinders due to the relationship of the cooling water temperature distribution, the mixture concentration distribution, and the like, and knocking is likely to occur in the order of 4d, 4a, 4b, and 4c.

The gasket substrate 1 of the gasket A includes the cylinders 4a, 4
Corresponding circular cylinder bore openings 2a, 2b, 2c, 2d are formed corresponding to b, 4c, 4d, respectively.

The gasket substrate 1 is a metal substrate in which flat plates and bead plates are alternately laminated. Metallic annular grommets 3a, 3b, 3c, 3d are attached to the periphery of the punching hole provided in the gasket substrate 1. , The cylinder bore openings 2a, 2b on the inner periphery thereof,
It is composed of 2c and 2d.

The grommets 3a, 3b, 3c, 3d have slightly different inner diameters Da, Db, Dc, Dd corresponding to the respective cylinders, in the order in which knocking of the corresponding cylinders easily occurs, that is, 4d, 4a, 4b. , 4c
The inner diameter is determined in accordance with. Therefore, the size of each opening area is in the order of Cd, Ca, Cb, and Cc in FIG.

The gasket A is clamped and fixed between the cylinder block 5 and the cylinder head 6 as shown in FIG.
At that time, the thickness t of the gasket A in the cylinder bore openings 2a, 2b, 2c, 2d is the same in all the cylinders.

Since the area of the cylinder bore opening, and hence the volume of the opening calculated by multiplying the area by the gasket thickness t, is different for each cylinder as described above, when the piston 7 is at the top dead center, The volume of each cylinder, that is, the size of the combustion chamber volume is in the order of the cylinders 4d, 4a, 4b, and 4c, and the magnitude of the compression ratio is determined in the reverse order.

In addition to the above-described embodiment, the present invention has grommets 3a, 3b, 3c for cylinder bore openings 2a, 2b, 2c, 2d corresponding to cylinders 4a, 4b, 4c, 4d, like a gasket B shown in FIG. 3d has a basic shape of a circular ring having the same diameter and is slightly deformed in the radial direction to form a required number (including zero) of the projections 8 so that the shapes are different from each other. , 4a, 4b, 4
According to c, the size of the opening area is increased in the order of Cd, Ca, Cb, and Cc. In this case, by selecting the number of protrusions of the protrusions 8 that protrude slightly in the radial direction, the area of the cylinder bore opening, and by extension, the volume of the opening can be finely increased or decreased.

Further, the present invention is not limited to the water-cooled type of the above embodiment, but can be applied to a cylinder head gasket used for an air-cooled multi-cylinder engine or a cylinder head gasket having a cylinder bore opening without a grommet.

(Effect of the Invention) According to the present invention, it is possible to provide a cylinder head gasket that is effective in preventing knocking, has a simple structure, is low in cost, and can finely adjust the compression ratio.

[Brief description of drawings]

1 is a plan view of an embodiment of the present invention, and FIG. 2 is a plan view of FIG.
FIG. 3 is an enlarged sectional view taken along the line II-II, FIG. 3 is a longitudinal sectional view of an essential part of the engine in which the gasket of FIG. 1 is fastened, and FIG. 4 is a plan view showing another embodiment of the present invention. A, B: Cylinder head gasket 2a, 2b, 2c, 2d ... Cylinder bore opening 4a, 4b, 4c, 4d ... Cylinder Ca, Cb, Cc, Cd ... Opening area

Claims (1)

[Scope of utility model registration request] 1. In a cylinder head gasket having a plurality of cylinder bore openings arranged in parallel, the opening area of the cylinder bore opening corresponding to a cylinder where knocking is likely to occur is larger than the opening area of the cylinder bore opening corresponding to a cylinder where knocking is unlikely to occur. Cylinder head gasket characterized by