JPS6117233Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device for an internal combustion engine that improves heat dissipation from a cylinder liner.

Increasing the output of the engine and taking measures to reduce exhaust emissions may increase the heat load and accelerate cylinder wear. On the other hand, if the cooling water flow in the water jacket formed between the outer peripheral surface of the cylinder runner and the cylinder block becomes stagnant or peels off from the outer peripheral surface of the cylinder runner, cavitation may occur and corrosion may be accelerated. .

By the way, it has been proposed that fins or grooves are provided on the outer peripheral surface of the cylinder runner to increase the heat dissipation area and improve the cooling performance, but in the conventional type, the fins or grooves are continuous all the way around the cylinder circumferential direction. The cooling water flow generally takes the form of rotating around the circumferential direction of the cylinder and gradually moving toward the cylinder axis, which tends to cause laminar flow in the circumferential direction, reducing the heat dissipation effect and preventing cavitation. Although this was the intended goal, there was a risk that it would actually encourage this.

In addition, with this configuration in which the cylinder runner is provided with fins and grooves, the outer diameter is larger than the inner diameter of the liner, so it is necessary to increase the cylinder pitch. becomes larger. If the cylinder runner is made thinner in order to avoid this drawback, the rigidity of the liner will be reduced, causing a resonance phenomenon in the liner and promoting the occurrence of cavitation and erosion.

This invention was made in view of the above, and
The present invention provides a cooling device that improves the heat dissipation of the cylinder runner while using the same cylinder runner as the conventional one, and has excellent cooling performance that can suppress the occurrence of cavitation and erosion.

In the figure, a water jacket 3 is provided to allow cooling water to flow between the outer peripheral surface of a cylinder runner 2 in which a piston (not shown) is slidably inserted and held, and the cylinder block 1 to which the liner 2 is attached. . Further, in the water jacket 3, a large number of protrusions 4 projecting from the cylinder block 1 toward the cylinder runner 2 are provided.

Therefore, the cooling water flowing inside the water jacket 3 generates turbulent flow at the back of the projection 4, so that the heat dissipation characteristics of the outer circumferential surface of the cylinder runner 2 are improved. In other words, when a laminar flow is formed on a solid surface, heat transfer within the liquid or gas is poor, and in contrast to the case where the liquid or gas stagnates in a thin layer on the solid surface, it is turbulent. When a flow is formed, the stagnant flow on the solid surface is destroyed, and at the same time, thermal conductivity (diffusivity) within the liquid or gas improves, improving cooling performance and preventing the occurrence of cavitation and erosion. It can be effectively suppressed. The number and position of the protrusions 4 are determined experimentally, but generally they should be placed facing the high temperature part of the cylinder runner 2 and the part where cavitation is likely to occur.

Further, the protrusion 4 is, for example, as shown in FIG. 3 A, B, C, D.
As shown in , the shape can be arbitrary as long as it causes turbulence in the flow of cooling water.

Furthermore, as shown in FIG. 4, even when the protrusions 4 are discontinued only in the circumferential direction of the water jacket 3 forming surface of the cylinder block 1, turbulent flow is generated at the back of the protrusions 4, and the same effect can be obtained. .

As explained above, according to the present invention, the heat dissipation characteristics of the cylinder runner and cylinder block can be improved even though the same cylinder runner as the conventional one is used and the cylinder block has an extremely simple structure of simply providing a protrusion. It is possible to improve this and at the same time suppress the occurrence of cavitation and erosion.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main parts showing one embodiment of the present invention, Fig. 2 is a - sectional view of Fig. 1, Fig. 3 is A,
B, C, and D are sectional views showing modified examples of the protrusion, respectively, and FIG. 4 is a sectional view of a main part of another embodiment. 1...Cylinder block, 2...Cylinder liner, 3...Water jacket, 4...Protrusion.

Claims (1)

[Claims for Utility Model Registration] (1) In an internal combustion engine in which a water jacket is formed between the outer circumferential surface of the cylinder liner and the cylinder block, the water jacket forming surface of the cylinder block is directed toward the outer circumferential surface of the cylinder liner. A cooling device for an internal combustion engine, characterized in that protrusions are disposed intermittently at least in a circumferential direction. (2) The cooling device for an internal combustion engine according to claim 1, wherein a plurality of protrusions are formed intermittently in the axial direction of the water jacket.