JPH0427710A - Cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE:To avoid defective cooling at the upper end part of a partition wall part by forming a cooling water passage at the upper end of each partition wall provided between cylinder bores in a cylinder block, and inducing part of cooling water in a cylinder head side water jacket to flow into this cooling water passage. CONSTITUTION:A cooling water passage 16 independently separated from a cylinder block side water jacket 12 is provided in the recessed state at the upper end of each partition wall part 15 provided between cylinder bores 11. Cooling water flows in such a way that part of coiling water flowing in a cylinder head side water jacket 24 flows toward a cooling water discharge passage 31 from a cooling water lead-in passage 30 through the cooling water passage 16 on the cylinder block 2 side. That is, part of relatively low temperature cooling water circulated in the cylinder head side water jacket 24 is forcibly led into the cooling water passage 16 on the cylinder block 2 side. The upper end part of the partition wall part 15 with high heat load can be thus cooled effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a cooling system for an internal combustion engine, and particularly to an improvement in a water-cooled cooling system that actively cools the cylinder head side compared to the cylinder block side.

Conventional technology In general, in internal combustion engines, in order to prevent abnormal combustion such as knocking, the temperature on the cylinder head side is kept relatively low, and friction due to the viscosity of lubricating oil is reduced and HC
In order to reduce this, it is desirable to keep the temperature on the cylinder block side relatively high.

Therefore, various cooling devices have been proposed in the past that do not uniformly cool the cylinder head side and the cylinder block side, but actively provide a temperature difference between the two sides.

For example, the cylinder head side water jacket and the cylinder block side water jacket are completely separated and independent, each is configured as a separate cooling water circulation system, and the set temperature of the cylinder head side cooling system is set relatively low. There is also a two-system type cooling system in which the set temperature of the cylinder block side cooling system is relatively high.

In addition, forced circulation of cooling water by the water pump is mainly carried out only through the cylinder head side water jacket, and natural convection occurs between the cylinder block side water jacket and the cylinder head side water jacket due to the temperature difference between the two. A cooling device with this structure has also been proposed (see Japanese Unexamined Patent Publication No. 56-52519, etc.). In other words, the cylinder head side is actively cooled by the low-temperature cooling water that has undergone heat exchange in the radiator flowing through the water jacket on the cylinder head side, whereas the cooling water in the water jacket on the cylinder block side flows through the water jacket on the cylinder head side. Since the wet coal simply flows up and down due to natural convection due to the temperature difference between it and the cooling water in the water jacket, the temperature of the wet coal becomes relatively high, and the cylinder wall temperature, which affects friction, etc., can be kept high.

Problems to be Solved by the Invention However, when configured to suppress cooling on the cylinder block side to keep the cylinder wall temperature high as described above, the partition wall between the cylinder bores (Siamese part), especially the upper end near the combustion chamber. The cooling performance of the piston ring tends to deteriorate, and there is a risk of excessive thermal distortion and seizure of the piston ring. Incidentally, it has been conventional practice to provide a cooling water passage in the partition wall by drilling or the like (for example, in Japanese Patent Publication No. 49-29
No. 966, etc.), since only the cooling water on the cylinder block side is guided to this cooling water passage, a sufficient cooling effect cannot be expected when the cylinder block side is heated to a high temperature as described above.

Means for Solving the Problems This invention has a cylinder head side water jacket and a cylinder block side water jacket inside the cylinder head and cylinder block, respectively.
In a cooling system for an internal combustion engine in which cooling water is forcibly circulated at least in a water jacket on the cylinder head side, a cooling water passage separate from the water jacket on the cylinder block side is formed at the upper end of a partition between cylinder bores in the cylinder block, and The cylinder head is characterized in that the lower deck of the cylinder head is provided with a cooling water inlet passage and a cooling water discharge passage which communicate each end of the cooling water passage with the cylinder head side water jacket.

Effect In the above configuration, a part of the cooling water flowing inside the water jacket on the cylinder head side flows into the cooling water passage between the cylinder bores through the cooling water inlet passage, and flows into the water jacket on the cylinder head side through the cooling water discharge passage. return. In other words, part of the cooling water on the cylinder head side flows through the cooling water passage, and the partition between the cylinder bores is actively cooled.

EXAMPLE Hereinafter, an example of the present invention will be explained in detail based on the drawings.

In this embodiment, as described above, the cylinder head L side is actively cooled by forced circulation of cooling water, and the cylinder block 2 side is cooled relatively weakly by natural convection due to temperature difference. FIG. 6 shows the overall configuration of the cooling system. In the figure, 3 indicates a radiator, and 4 indicates a water pump. The low-temperature cooling water that has undergone heat exchange with the radiator 3 is sucked into the water pump 4 via a passage 5 and a thermostatic valve 6, and from there is passed through a passage 7. The cooling water is fed under pressure to the rear end of the cylinder head 1.Then, it flows through the cylinder head 1 in the front-rear direction and circulates from the front end cooling water outlet to the laryator 3 via the passage 8. This is a bypass passage through which cooling water circulates.

The first iffl is a partially cutaway perspective view showing the cylinder head 1 and the cylinder block 2. The cylinder block 2 has a plurality of cylinder bores 11 formed therethrough, and the cylinders surround the cylinder bore 11. A block side water jacket 12 is formed. Here, the cylinder block 2 has a cylinder bore 1
The cylinder walls of each cylinder forming the cylinder 1 are partially continuous in a so-called Siamese type. The cylinder block side water jacket 12 is attached to the upper deck 13.
It is a closed deck type in which the upper end is closed by a hole, and the communication hole 1 opens to the above-mentioned oil pump I3 so as to allow only a slight flow of cooling water due to natural convection.
4 is set very small.

As shown in FIGS. 2 and 4, cooling water passages 16 are provided in the upper ends of the partition walls 15 between the cylinder bores 11 in the form of arcuate slits. This cooling water passage 16 is machined using a disk-shaped cutter, and is not in communication with the cylinder block side water jacket 12, but is in a separate and independent state. Furthermore, an inlet portion 16a and an outlet portion 16b consisting of circular holes are drilled at each end of the cooling water passage 16.

Note that 17 is a screw hole into which a cylinder head bolt (not shown) is screwed.

On the other hand, in the cylinder head l fixed to the upper surface of the cylinder block 2, an intake boat 21 and an exhaust boat 22 are formed in a cross-flow type, and an ignition plug mounting part 23 is provided toward the center of the cylinder bore II. A cylinder head side water jacket 24 is formed to surround the cylinder head and the cylinder head. This cylinder head side water jacket 24 has a communication hole 25 (see FIG. 3) opened on the lower surface and a cylinder block 2
It communicates with the cylinder block side water jacket 12 via the side communication hole 14. Further, a cooling water inlet 26 into which the cooling water discharged from the water pump 4 flows is formed on the rear end surface of the cylinder head l, particularly at a position biased toward the exhaust boat 22 side, and the cylinder head l (not shown) A cooling water outlet is provided at the front end. Therefore, as described above, the main flow of the cooling water flows inside the cylinder head side water jacket 24 from the rear end side to the front end side.

And, on the lower deck 27 of the cylinder head l,
As shown in FIG. 3, a pair of metal pipes 28 and 29 are press-fitted in correspondence with the cooling water passages 16 of the partition wall 15, and the cooling water passes through the lower deck 27 with each metal pipe 28 and 29. A water introduction passage 30 and a cooling water discharge passage 31 are formed. The metal pipe 28 that will become the cooling water introduction path 30 is located at a position that matches the inlet portion 16a of the cooling water passage 16, and the metal pipe 29 that will become the cooling water discharge path 31 is located at a position that matches the inlet portion 16a of the cooling water passage 16.
is located at a position that matches the outlet portion 16b of the cooling water passage 16,
The cooling water passage 16 on the cylinder block 2 side is connected to the water jacket 24 on the cylinder head side.
It communicates with

Further, the upper end portion of each metal pipe 28, 29 projects into the cylinder head side water jacket 24, and the tip thereof is cut diagonally at an angle of about 45°. In particular, the metal pipe 28 that becomes the cooling water introduction path 30 is arranged in the cylinder head so that its tip opening faces the main flow of the cooling water! It is cut diagonally towards the rear end. On the other hand, the metal pipe 29 which becomes the cooling water discharge path 31 is cut obliquely toward the front end of the cylinder head l so as to face downstream of the main flow of the cooling water (see FIG. 5).

Therefore, in the above configuration, with the main flow of cooling water flowing inside the cylinder head side water jacket 24, a pressure difference is generated between the tip openings of both metal vibrators 28 and 29, and as shown in FIG. Cooling water flows from the introduction passage 30 to the cooling water discharge passage 31 via the cooling water passage 16 on the cylinder block 2 side. In other words, a portion of the relatively low-temperature cooling water circulating inside the cylinder head side water jacket 24 is forcibly introduced into the cooling water passage 16 on the cylinder block 2 side, effectively discharging the upper end portion of the partition wall 15 that has a high heat load. can be cooled to

Next, FIG. 7 shows a different embodiment of the invention.

In this embodiment, the lower deck 27 of the cylinder head 1 is provided with an artificial part 16a of the cylinder block 2 side cooling water passage 116.
A cooling water inlet passage 30 and a cooling water discharge passage 31 corresponding to the outlet portion 16b are formed directly through the outlet portion 16b. In order to provide a pressure difference between the two, arc-shaped projections 32 and 33 are formed on the bottom surface of the water jacket 24 on the upper end opening side, that is, on the cylinder head side.

The protrusion 32 for the cooling water introduction path 3o is provided on the downstream side of the opening with respect to the main flow of the cooling water, and is adapted to receive and guide the main flow of the cooling water to the cooling water introduction path 30.

Moreover, the protrusion 33 for the cooling water discharge path 31 is provided upstream of the opening with respect to the main flow of the cooling water. In this illustrated example, both protrusions 32 and 33 are continuous, forming an S-shape as a whole.

Also in the configuration of this embodiment, a part of the cooling water circulating inside the cylinder head side water jacket 24 is transferred to the cooling water passage 16 on the cylinder block 2 side, similar to the above-mentioned embodiment.
be forcibly guided to

Effects of the Invention As is clear from the above explanation, according to the cooling device for an internal combustion engine according to the present invention, a cooling water passage is formed at the upper end of the partition wall between the cylinder bores in the cylinder block, and the water jacket on the cylinder head side is formed here. Since a portion of the cooling water is allowed to flow through the partition wall, this may cause problems when cooling is weakened on the cylinder block side compared to the cylinder head side using dual-system cooling or natural convection cooling. It is possible to avoid poor cooling at the upper end of the unit. Furthermore, since the upper end of the partition wall, which has a high heat load, can be cooled well, it is possible to make the partition wall thinner, that is, to shorten the bore pitch, which is advantageous in shortening the overall length of the internal combustion engine.

[Brief Description of the Drawings] Fig. 1 is an exploded perspective view showing a cylinder block and cylinder head equipped with a cooling device according to the present invention, partially cut away, and Fig. 2 shows the upper end surface of the main parts of the cylinder block. FIG. 3 is a cross-sectional view of the main parts of the cylinder head, FIG. 4 is a cross-sectional view of the main parts when the cylinder head and cylinder block are connected, and FIG. 5 is a perspective view of the main parts of the cylinder head. , FIG. 6 is a structural explanatory diagram showing the entire cooling system of this embodiment, and FIG. 7 is an exploded perspective view similar to FIG. 1 showing a different embodiment of the present invention. 1... Cylinder head, 2... Cylinder block,
12...Cylinder block side water jacket, 1
5... Partition wall portion, 16... Cooling water passage, 24... Cylinder head side water jacket, 30... Cooling water introduction passage, G... Cooling water discharge passage. Figure 2 Figure n

Claims (1)

[Claims] (1) A cooling system for an internal combustion engine that has a cylinder head side water jacket and a cylinder block side water jacket inside the cylinder head and cylinder block, respectively, and in which cooling water is forcibly circulated at least in the cylinder head side water jacket. A cooling water passage separate from the cylinder block side water jacket is formed at the upper end of the partition between the cylinder bores in the cylinder block, and a cooling water passage separated from the cylinder head side water jacket is formed at each end of the cooling water passage and the cylinder head side water jacket on the lower deck of the cylinder head. 1. A cooling device for an internal combustion engine, comprising a cooling water inlet passage and a cooling water discharge passage that communicate with each other.