JPS5840258Y2 - Combustion chamber of internal combustion engine - Google Patents

Description

[Detailed description of the invention] This invention relates to the combustion chamber of an internal combustion engine, and improves the flow of air-fuel mixture and flame propagation to improve output.

Some 4-stroke engines are of the so-called 4-valve type, in which two inlet valves and two exhaust valves are provided in order to improve intake and exhaust efficiency.

This four-valve engine also has an inlet hole and an exhaust hole on a flat surface, and a ridge line in the center of the inside of the cylinder head, with hemispherical swirl combustion chambers on both sides of this ridge line. There are some that have formed.

It has been confirmed that the latter burns better than the former.

In this latter type of engine, a plug mounting hole for installing a spark plug is drilled in the center of the ridgeline, but the area around this plug mounting hole is designed to prevent cracks from occurring due to stress concentration during operation. In order to do this, chamfering will be applied.

Conventionally, it has been thought that it is best to make the size of this chamfer as small as possible.

However, the size of this chamfer is somewhat large,
That is, it has been confirmed through experiments that combustion efficiency can be increased when the cylinder bore diameter is set within a certain range.

This idea was made in consideration of this point, and instead of chamfering to prevent cracks starting from the vicinity of the plug mounting hole, it stipulates the size of the chamfer so that maximum output can be obtained. It is something.

Next, an embodiment of this invention will be described with reference to the drawings. In FIG. 1, numeral 1 indicates a cylinder head, as seen from the combustion chamber side.

This cylinder head 1 is provided with inlet types 2, 3 and exhaust holes 4, 5 as shown in the figure, and an inlet valve and an exhaust valve (both not shown) can be attached to the cylinder head 1, respectively.

A ridge line 6 is formed between the two inlet holes 2 and 3 and between the two exhaust holes 4 and 5, and this portion becomes higher and protrudes toward the piston side (not shown). There is.

As shown in FIG. 2, an arcuate portion 8 is formed between this ridgeline 6 and a ridgeline 71 near the outer periphery.

9 is a cylinder, and the inside thereof becomes a combustion chamber 10.

A plug attachment hole 11 is provided at the center of the ridgeline 6.

Then, on the ridgeline 6 centered on this plug mounting hole 11,
As shown in FIGS. 1 and 3, a chamfer 12 having a length LO030 to 0.35 D is provided relative to the bore diameter of the cylinder 9.

Note that the angle θ of the chamfer 12 is approximately 110°.

The portion indicated by the reference numeral 13 in FIG. 1 is a flat portion, which acts as a so-called squish area.

This cylinder head configured in this way has the following features:
In the process in which a piston (not shown) moves up inside the cylinder 9 and compresses the air-fuel mixture, the air-fuel mixture in the combustion chamber 10 flows toward the plug mounting holes 11 at the arcuate portions 8, and furthermore, at the chamfered portions 12. The current flows better to a spark plug (not shown) where it is ignited.

This improves flame propagation and improves output.

According to experiments, when the length L't of the chamfer 12 is set within the range of the bore diameter of the cylinder 9 multiplied by 0.30 NO, 35x, the output is high as shown in Figure 4. It became a thing.

Since this invention is constructed as described above, it has the advantage of being able to improve the output of the engine very easily.

[Brief explanation of the drawing]

Figure 1 is a bottom view of the cylinder head with this invention, Figures 2 and 3 are cross-sectional views along the ■-■ line and ■-■ line in Figure 1, respectively, and Figure 4 is the output confirmed by experiment. It is a characteristic diagram. 1... Cylinder head, 2.3... Inlet hole. 4.5...Exhaust hole, 6...Ridge line, 9...
Cylinder, 11... Plug mounting hole, 12... Chamfer, D... Bore diameter, L... Chamfer length.

Claims (1)

[Scope of utility model registration request] In a 4-valve internal combustion engine, the 2 valves inside the cylinder head
A plug mounting hole is provided in the center of the ridgeline extending between the two inlet holes and the two exhaust holes, and the plug mounting hole is located on the ridgeline with the plug mounting hole in the center, and its length is 0.30 to A combustion chamber for an internal combustion engine, characterized in that it is chamfered to a value multiplied by 0.35.