JPS6128016Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a piston cooling device for an internal combustion engine that improves the cooling effect of oil.

It is generally well known that increasing the compression ratio is effective in improving the fuel efficiency of internal combustion engines. However, when increasing the compression ratio of an engine, knocking becomes severe in the high load region, especially in the high load region at low and medium speeds, and increasing the compression ratio is restricted due to the occurrence of knocking. is the current situation.

On the other hand, knotting occurs when unburned gas in a high-temperature part of the combustion chamber located away from the ignition plug spontaneously ignites before the flame reaches it due to its high temperature and compression due to rapid flame expansion around the ignition plug. It is well known that this is caused by The combustion chamber is formed as a space surrounded by the top surface of the piston, the bottom surface of the cylinder head, and the inner peripheral surface of the cylinder block bore, so in order to reduce the temperature of the high temperature part of the combustion chamber wall and suppress the occurrence of knocking. In addition, it is desirable to keep the temperature of the piston, especially the top surface of the piston, low.

Conventional piston cooling is carried out by forming the piston from an aluminum alloy, forming oil holes in the crankshaft, connecting rod, etc. from below, and spraying oil onto the piston from the oil holes. However, with this type of conventional piston cooling, the oil that is sprayed on the bottom surface of the piston falls under its own weight before it makes sufficient contact with the bottom surface of the piston, so the oil cannot sufficiently remove the heat from the piston. The cooling efficiency of oil was extremely poor. Additionally, since the oil is usually sprayed locally on a portion of the bottom surface of the piston, the temperature at the top of the piston is reduced unevenly, which may result in not being able to effectively cool the high-temperature area, and causing damage to the piston. There was also the possibility that another problem would occur: uniform thermal distortion would occur, accelerating the wear of piston rings and the like.

In order to solve these conventional problems, the present invention increases the contact time of oil with the lower surface of the piston, that is, increases the time that the oil is retained by the piston, and cools the lower surface of the piston uniformly. An object of the present invention is to provide a piston cooling device for an internal combustion engine.

In order to achieve this purpose, in the piston cooling device for an internal combustion engine of the present invention, a porous body made of metal wool, porous alloy, etc. is attached to the lower surface of the top surface of the piston by a casting or the like. Ori,
By sprinkling oil onto this porous body, the oil retention time is extended.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 and 2 show cross sections of the device of this embodiment. In the figure, 1 is a piston body made of an aluminum alloy, and a porous body 4 is attached to the back side 3 of the top surface 2 of the piston body. The lower surface of the porous body 4 is exposed, and when oil is sprayed from below, the oil will directly wet the porous body 4. The porous body 4 is attached to the entire area of the back side 3 of the top surface 2 except for the outer circumferential wall portion 6 that connects to the skirt portion 5.

The porous body 4 is made of a heat-resistant porous body that can sufficiently retain oil, such as a porous aluminum alloy or aluminum wool. The porous body 4 may be attached to the piston 1 by any attachment method as long as it does not fall off from the piston 1. For example, the porous body 4 may be attached by casting using the ring 7.

A means for spraying oil onto the porous body 4 is provided below the porous body 4. The illustrated oil sprinkling means 8 is connected to a connecting rod 9.
A case is shown in which the oil injection hole is formed from an oil injection hole formed in the small end 10 of the oil injection hole. The oil led from the oil pan to the cylinder block via the oil pump is sent to this oil spout hole through an oil passage 11 formed in the crankshaft and connecting rod 9, and then to the porous body 4. It is starting to be ejected towards the target.

The means for spraying oil onto the porous body 4 is not limited to the structure described above, but may be any means that sprays oil toward the porous body 4 from below, such as an oil spouting hole in the crankshaft. may be provided.

In the piston cooling device configured as described above, the oil sprayed onto the porous body 4 from the oil spout holes 8 is sucked into the porous body 4, is retained in the porous body 4 for a relatively long time, and is directed downward. fall to Therefore, the oil can come into contact with the top back side 3 of the piston 1 reliably and for a sufficient period of time, thereby efficiently cooling the top back side 3 of the piston. Further, since the porous body 4 is porous, the surface area in contact with the liquid is extremely large, and the cooling effect is also improved due to a dramatic increase in the cooling area.
This also reduces the temperature of the top surface 2 of the piston 1.

Moreover, since the porous body 4 is provided over almost the entire area of the back side 3 of the top surface of the piston, the back side 3 of the top surface of the piston is uniformly cooled. In these cooling operations, cooling is performed not only by removing heat from the oil while it is in a liquid state, but also by evaporation of the oil.

The oil cooling device for an internal combustion engine according to the present invention is provided with a porous body on the back side of the top surface of the piston, so that the piston top surface is The effect is that the temperature can be lowered efficiently and uniformly. By lowering the combustion chamber wall temperature of the internal combustion engine, the compression ratio can be increased while suppressing the occurrence of knocking, and by increasing the compression ratio, it is possible to improve the fuel efficiency of the engine.
By advancing the ignition angle, shaft torque can be improved,
The ultimate effect of improving drivability is also achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a piston cooling device for an internal combustion engine according to the present invention, and FIG. 2 is a sectional view taken along a plane perpendicular to FIG. 1. 1... Piston, 2... Piston top surface, 3...
Rear side of the top surface of the piston, 4... Porous body, 8... Oil sprinkling means, 9... Connecting rod.

Claims (1)

[Claims for Utility Model Registration] (1) A porous body is attached to the back side of the top surface of the piston of an internal combustion engine, and a means for spraying oil onto the porous body is provided below the porous body. Features a piston cooling system for internal combustion engines. (2) Utility Model Registration Scope of Claim 1: The piston cooling device for an internal combustion engine according to claim 1, in which the porous body is made of either metal wool or a porous alloy. (3) Utility Model Registration Scope of Claim 1: The piston cooling device for an internal combustion engine as set forth in claim 1, wherein the oil sprinkling means comprises an upwardly opening oil hole provided in a conrod.