JPS6347630Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cooling device for an internal combustion engine that reduces the wall temperature of the upper end portion of a cylinder bore among the walls of a combustion chamber.

[Prior Art] It is generally well known that increasing the compression ratio is effective in improving the fuel efficiency of internal combustion engines. However, when trying to increase the compression ratio of an engine, knocking becomes severe in the high load region, especially in the high load region of 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 is located away from the spark plug.
It is well known that this is caused by spontaneous ignition before the flame arrives due to the high temperature and compression caused by rapid flame expansion around the spark plug.
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 inner circumferential surface of the cylinder bore low, especially of the inner circumferential surface of the upper end of the cylinder bore up to 15 to 20 degrees after top dead center, which is involved in the occurrence of knocking.

By the way, there are inventions such as Japanese Patent Application Laid-open Nos. 117027/1982 and 12014/1983 that incorporate a special member at the upper end of the cylinder bore, but these inventions include ceramic material for electrical insulation. Because the heat conductivity is poor and the inner circumferential surface of the upper end of the cylinder bore becomes hot, it also has a large heat capacity and does not spread to other walls of the combustion chamber, as shown in Japanese Utility Model Application Publication No. 55-112023. There have been proposals to attach a cylindrical ring that is hotter, but this actually makes it easier for knotting to occur, and none of them have been designed to suppress the occurrence of knotting.

[Problem to be solved by the invention] The purpose of the invention is to reduce the temperature of the inner circumferential surface of the upper end of the cylinder block bore by installing a special member at the upper end of the cylinder block bore. Specifically, the purpose is to suppress the occurrence of knocking, improve fuel efficiency, improve shaft torque, and improve drivability.

[Means for Solving the Problems] A cooling device for an internal combustion engine according to the present invention that meets this objective has an inner diameter that is the same as the cylinder bore formed by the cylinder block, and a cylinder that has the same inner diameter as the cylinder bore formed by the cylinder block. A spacer facing the combustion chamber and forming a part of the cylinder bore and made of a material with good thermal conductivity is interposed, and a heat insulating material is interposed between the spacer and the lower surface of the cylinder head and the upper surface of the cylinder block. At the same time, the spacer is provided with a cooling water passage that passes through the spacer, and the thickness of the spacer is such that the inner diameter surface of the spacer is at least 15 degrees from the top dead center of the piston at a crank angle. Consists of what you set to configure.

The material of the spacer is copper, aluminum alloy, or the like.

[Function] In such a cooling device, the spacer is cooled by the cooling water flowing through the cooling water passage, and since the spacer is made of a material with good thermal conductivity, it is exposed to the cylinder bore surface and the spacer is exposed to the cylinder bore. The inner diameter surface of the spacer, which forms part of the spacer, is also cooled. Since the spacer is thermally isolated from the cylinder head and cylinder block by the heat insulating material on both sides thereof, the temperature of the inner diameter surface of the spacer is effectively kept low. The inner diameter surface of the spacer, which is kept at a low temperature, constitutes the cylinder bore surface up to at least a position corresponding to a crank angle of 15 degrees at the upper end of the cylinder bore, so that the wall surface of the combustion chamber, which tends to cause knocking, is effectively cooled.

[Embodiments] Hereinafter, preferred embodiments of the cooling device for an internal combustion engine of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross section of an embodiment of the present invention, and FIG. 2 shows an example of the shape of the spacer. In the figure, 1 is a cylinder head, 2 is a cylinder block, and a spacer 3 is interposed between them. The spacer 3 has a hole 5 having the same inner diameter as the cylinder bore 4 formed in the cylinder block 2, and by being mounted concentrically, the hole 5 as the inner diameter surface is a part of the inner peripheral surface of the upper end of the cylinder bore 4. is formed.

The spacer 3 is made of a material with good thermal conductivity, such as copper or aluminum alloy. The spacer 3 should be thick enough to be located at the upper end of the cylinder bore at least 15 degrees, preferably 15 to 20 degrees after the piston top dead center, which is involved in the occurrence of knocking at the crank angle, relative to the top surface of the piston. It is often constructed from a flat plate, usually up to 20mm thick. Gaskets 6 and 7 are interposed between the spacer 3 and the cylinder head 1 and cylinder block 2, which also function as heat insulators. In order to prevent the gasket 7 interposed between the spacer 3 and the cylinder block 2 from interfering with the first piston ring 9 of the piston 8, the thickness of the spacer 3 is set to be smaller than the top land of the piston 8. height,
That is, it is smaller than the height from the upper end of the first piston ring 9 to the upper end of the piston 8 minus the thickness of the gaskets 6 and 7.

Cooling water passages 10, 11, 12 are provided in the spacer 3 and gaskets 6, 7, respectively.
The water jacket 13 of the cylinder block 2 and the water jacket 14 of the cylinder head 1 communicate with each other via the cooling water passages 10, 11, 12. Cooling water passages 10, 11, 12
As shown in FIG. 2, it extends in an arc shape around the cylinder bore 4, and is designed to cool a large portion of the circumferential surface of the bore 4. In addition, the second
In the figure, 15 is a bolt hole.

In the apparatus configured as described above, cooling is performed as follows. In other words, the combustion chamber wall becomes high in temperature due to combustion during the explosion stroke, but the heat on the inner diameter surface of the upper end of the cylinder bore 4, that is, the inner circumferential surface of the hole 5, which is involved in the occurrence of knocking, is transferred through the spacer 3, which has good thermal conductivity. The heat is transmitted to the cooling water passage 10, where the heat is radiated to the cooling water flowing from the water jacket 13 of the cylinder block 2 to the water jacket 14 of the cylinder head 1. The inner circumferential surface of the hole 5 of the spacer 3, that is, the inner circumferential surface of the spacer 3, constitutes a part of the cylinder bore and is completely exposed to the cylinder bore surface, so this part of the combustion chamber is strongly and effectively cooled. Ru. After cooling the cylinder head 1, the heated cooling water is conveyed to the radiator, where it is cooled and circulated to the cylinder block 2.

The inner circumferential surface of the hole 5 at the upper end of the cylinder bore is cooled more efficiently than the surrounding area and has a low temperature, but this low temperature is achieved by the spacer 3 insulating heat from the cylinder head 1 and cylinder block 2 by the gaskets 6 and 7. Therefore, there is no thermal influence from the cylinder head 1 or cylinder block 2. By cooling the upper end wall surface of the cylinder bore 4, the end gas is cooled, and knocking becomes less likely to occur.

Moreover, the inner diameter surface of the spacer 3 to be cooled is
Since the piston extends to a crank angle of about 15 degrees after the piston top dead center where knocking is likely to occur, the above cooling can most efficiently suppress the occurrence of knocking.

[Effects of the invention] When using the cooling device for an internal combustion engine of the invention, the spacer is made of a material with good thermal conductivity, and both sides are insulated for efficient cooling. Since the directly exposed inner diameter surface of the spacer can be strongly cooled, the wall temperature at the upper end of the cylinder bore, which is involved in the occurrence of knotting, can be efficiently lowered, and the end gas in the area away from the spark plug can be cooled. can. As a result, the occurrence of knocking is suppressed, so it is possible to advance the engine's compression ratio, which not only improves fuel efficiency but also advances the ignition angle. This has the effect of increasing shaft torque and improving drivability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a cooling device for an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a plan view of a spacer portion of the device shown in FIG. 1... Cylinder head, 2... Cylinder block, 3... Spacer, 4... Cylinder bore, 5...
...Spacer hole, 6,7...Gasket, 8...
Piston, 9...First piston ring, 10,1
1, 12...Cooling water passage.

Claims (1)

[Claims for Utility Model Registration] (1) The cylinder head and cylinder block have the same inner diameter as the cylinder bore formed by the cylinder block, and the inner diameter surface faces the combustion chamber and forms part of the cylinder bore. In addition, a spacer made of a material with good thermal conductivity is interposed, and a heat insulating material is interposed between the spacer and the lower surface of the cylinder head and the upper surface of the cylinder block, respectively, and cooling water is inserted into the spacer. A passage is provided, and the thickness of the spacer is set such that the inner diameter surface of the spacer constitutes a cylinder bore at a position at least 15 degrees after top dead center at a crank angle with respect to the top surface of the piston. cooling system for internal combustion engines. (2) The cooling device for an internal combustion engine according to claim 1, wherein the thickness of the spacer is smaller than the thickness of the heat insulating material subtracted from the top surface of the piston. (3) The cooling device for an internal combustion engine according to claim 1, wherein the spacer is made of either copper or aluminum alloy.