JPH0326251Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to improvements in cooling systems for internal combustion engines, particularly water-cooled cooling systems.

BACKGROUND OF THE INVENTION In general, a forced circulation pressurization system is often used as a water cooling system for an automobile internal combustion engine, and one example is an in-line system as shown in FIG.

Briefly, water jackets 5 and 6 are formed inside the cylinder block 2 and cylinder head 3 of the engine 1, respectively, and communicate with each other through a communication hole 4. During normal operation, the coolant that has absorbed heat is pumped to the radiator 9 via the coolant outlet passage 8 by the action of the water pump 7, where it radiates heat, and is further transferred to the water jacket on the cylinder block side via the coolant introduction passage 12. 5 and flows into the water jacket 6 on the cylinder head side to cool various parts of the engine. On the other hand, when the water temperature is low such as during a cold start, the cooling water outlet passage 8 is blocked by the operation of the thermostat 10 that maintains the engine's proper operating temperature, so the cooling water is routed through the bypass passage 11 without passing through the radiator 9. The water is circulated through the water jackets 5 and 6 (Automotive Engineering Complete Book Volume 4 Gasoline Engine, Sankaido Co., Ltd., Showa
Published July 20, 1955, see pages 359-360).

Problems that the invention aims to solve By the way, in the case of internal combustion engines, as is well known, the vicinity of the upper deck 2a of the cylinder head 3 and cylinder block 2 is exposed to the highest temperature due to repeated explosions and combustion; must be sufficiently cooled. On the other hand, the area near the lower deck 2b of the cylinder block 2 is not directly affected by explosive combustion and therefore remains relatively low temperature at all times, and does not require as much cooling as the cylinder head 3 and the like.

However, in the conventional cooling system described above, most of the cooling water that has been sufficiently cooled by the radiator 9 first flows into the water jacket 5 near the lower deck 2b of the cylinder block 2, as shown by the arrow in the figure. After flowing in and sufficiently absorbing heat and cooling the vicinity of the lower deck 2b, it rises and flows into the water jacket 6 on the cylinder head side, so that the cooling effect in the vicinity of the cylinder head 3, which is most in need of cooling, becomes insufficient. As a result, a knocking phenomenon occurs due to overheating, resulting in a decrease in combustion efficiency, resulting in poor fuel efficiency. Moreover, the lower cylinder block 2
The area around the deck 2b is unnecessarily cooled and becomes supercooled, and as shown in FIG.
The temperature difference between the lower deck 2b and the lower deck 2b increases. This leads to friction loss and deterioration of fuel efficiency due to uneven temperature distribution, and especially in multi-cylinder engines, there is a large temperature difference between the front and rear ends and the center of the engine.
This has led to each of the above problems. Also, Utsukai Showa 58-
As in the invention described in Japanese Patent No. 149517, the water jacket on the cylinder head side is connected to the cylinder head side through a water duct that extends through the water jacket on the cylinder block side and a temperature-sensitive on-off valve provided at the downstream end of the water duct. Some systems have been proposed which introduce most of the cooling water directly into the bucket. but,
This idea aims to improve warm-up and heating performance by allowing most of the cooling water to flow directly into the water jacket on the cylinder head side only during a cold start. The on-off valve is closed to block the flow of cooling water into the water jacket on the cylinder head side, while allowing the water to flow into the lower end of the water jacket on the cylinder block side. For this reason, problems such as the inability to obtain a sufficient cooling effect of the cylinder head during normal operation, similar to the above-mentioned prior art, have arisen.

Means for Solving the Problems This invention was devised in view of the above-mentioned conventional problems, and includes a first water jacket formed in the cylinder block of an internal combustion engine, and a first water jacket formed in the cylinder head. a second water jacket;
A communication path that communicates the first and second water jackets, one end of which is connected to the water pump side front end of the second water jacket, and the other end of which is connected to the lower part of the radiator. comprising a connected cooling water introduction passage, and a cooling water outlet passage whose one end is connected to the rear end of the second water jacket and whose other end is connected to the upper part of the radiator, At least during normal operation of the engine, the engine cooling water that has flowed into the radiator from the cooling water outlet passage is constantly forcedly circulated into the second water jacket via the cooling water introduction passage;
The engine cooling water in the second water jacket is characterized by natural convection in the first water jacket via the communication passage.

According to this invention having the above configuration, during normal operation after warm-up is completed, the cooling water flowing into the engine from the radiator by the action of the water pump is directly transferred to the water jet on the cylinder head side via the cooling water introduction passage. After being introduced into the cylinder head water jacket and flowing from the front end to the rear end of the water jacket on the cylinder head side to perform a sufficient heat exchange action, it is taken out from the opening of the cooling water outlet passage and the cooling water is discharged. It is led to the radiator through a passage. In this way, since the water is forced to circulate only within the water jacket on the cylinder head side, the cylinder head and the vicinity of the upper deck of the cylinder block, which are exposed to high temperatures, are sufficiently cooled.

On the other hand, the cooling water in the water jacket on the cylinder block side is not forced to circulate, but instead flows up and down due to natural convection as the temperature changes, and heat exchange occurs within the water jacket on the cylinder head side via the communication holes. The cylinder block is cooled down. This eliminates temperature differences between the upper and lower positions of the cylinder block and between each cylinder, making the overall temperature distribution approximately uniform, and as a result, friction loss in each part of the engine is reduced.

Embodiment Hereinafter, an embodiment of this invention will be described in detail based on the drawings.

Figure 1 is a cross-sectional view of an in-line cooling system in which this invention is applied to a four-cylinder internal combustion engine.
In the figure, 11 is the engine body, 12 is the cylinder block 1
The first water jacket on the 3 side, 14 the second water jacket on the cylinder head 15 side, 1
Reference numeral 6 denotes a communication hole that is a communication path that communicates the water jackets 12 and 14, 17 is a water pump provided on the front end side of the engine body 11, and 18 is a radiator, which connects the radiator 18 and the water on the cylinder head side. Between the jackets 14 are a cooling water introduction passage 19 and a cooling water outlet passage 20 for circulating cooling water.
are arranged respectively. That is, one end 19a of the cooling water introduction passage 19 is connected to the front end 14a of the water jacket 14 on the cylinder head side of the water pump 17, and the other end 19b is connected to the lower tank of the radiator 18. 18a. On the other hand, one end 20a of the cooling water outlet passage 20 is connected to the rear end 14b of the cylinder head side water jacket 14, and the other end 20b is connected to the radiator 1.
It is connected to No. 8 Atsupa tank 18b.

In addition, 21 in the figure is a bypass passage that bypasses the radiator 18, and this bypass passage 2
1 has an upstream end connected to the vicinity of the other end 20b of the cooling water outlet passage 20, and a downstream end connected to the vicinity of the one end 19a of the cooling water introduction passage 19. 22
A thermostat is disposed in the middle of the cooling water outlet passage 20 and opens and closes the bypass passage 21 according to the temperature of the cooling water.

Therefore, according to this embodiment having the above configuration, first, when the engine is cold started, the thermostat 21 opens the bypass passage 21 while the other end 20b of the cooling water outlet passage 20 and the radiator 18 are opened.
In order to cut off the communication with the radiator 18, the cooling water flowing by the action of the water pump 17 is
The cooling water is prevented from flowing into the cylinder head side water jacket 14 from the cooling water introduction passage 19, and from there flows into the cooling water introduction passage 19 again via the cooling water outlet passage 20 and the bypass passage 21.
Therefore, the cooling water circulation path is shortened,
The substantial amount of cooling water flowing into the water jacket 14 on the cylinder head side is reduced, which improves the rise in the cooling water temperature and improves warm-up and heating performance.

During normal operation after completion of warm-up, the thermostat 21 closes the bypass passage 21, and in order to communicate the cooling water outlet passage 20 and the radiator 18, the action of the water pump 17 causes the water to be supplied from the radiator 18. As shown by the solid line arrow in the figure, the cooling water flows directly into the cylinder head side water jacket 14 through the cooling water introduction passage 19 and flows from the front end 14a to the rear end 14b of the water jacket 14. After that, the cooling water is taken out from the opening 23 on the one end 20a side of the cooling water outlet passage 20 as shown by the chain arrow, returned to the radiator 18, and forcedly circulated only in the water jacket 14 on the cylinder head side. Ru. As a result, the cylinder head 15 and the vicinity of the upper deck 13a of the cylinder block 13 are sufficiently cooled, the knocking phenomenon due to overheating is prevented, and combustion efficiency and fuel efficiency can be sufficiently improved.

On the other hand, the cooling water in the water jacket 12 on the cylinder block side is not forced to circulate, but simply performs its cooling action by natural convection accompanying thermal changes. That is,
High temperature cooling water is introduced into the communication hole 16, exchanges heat with the cooling water in the water jacket 12, and descends again to cool the entire cylinder block 13. Therefore, as shown in FIG. 2, the area around the lower deck 13b of the cylinder block 13 is not overcooled, and together with the cooling effect on the cylinder head 15 side, the upper deck 13a and the lower deck are cooled. The temperature difference near 13b has slightly disappeared and is now about ¹⁴⁰⁰ to 150°C. By making this temperature distribution uniform, especially the temperature between each cylinder,
Not only can friction loss be reduced, which is advantageous against thermal distortion, but it can also help improve fuel efficiency.

In addition, the cylinder block 13 is cooled by natural convection of cooling water, and there is no need to ensure a good water circulation within the water jacket 12. Therefore, the water jacket 13 is cooled as shown in FIGS. It becomes possible to form reinforcing ribs 30 between the partition walls of the butt 12. Therefore, the rigidity of the cylinder block 13 is significantly improved, and engine noise can be sufficiently reduced.

Effects of the invention As is clear from the above explanation, according to the cooling system for an internal combustion engine according to the invention, at least during normal operation, the cooling water cooled by the radiator is directly supplied to the second water jet on the cylinder head side. Since the cylinder is forced to circulate only within the bucket, the cylinder head and the upper part of the cylinder block, which are exposed to high temperatures, are sufficiently cooled. Therefore, the knocking phenomenon caused by overheating is reliably prevented, and combustion efficiency and thereby fuel efficiency can be improved.

In addition, since the cylinder block side is cooled by natural convection rather than forced circulation of cooling water, the temperature distribution throughout the cylinder block is approximately uniform, reducing friction loss and further improving fuel efficiency. It is also extremely advantageous against thermal strain.

In addition, the present invention mainly cools the cylinder head by simply circulating cooling water to the cylinder head side, which improves cooling efficiency and allows for smaller radiators and water pumps with smaller capacities. This increases the degree of freedom in the layout of radiators, etc., and is advantageous in terms of cost.

Incidentally, it is also possible to apply the present invention to a cooling device using a bottom-by-bus system or the like, depending on the implementation.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the cooling system for an internal combustion engine according to this invention, and Fig. 2 shows a comparison of the temperature distribution state of the cylinder liner wall temperature between a conventional cooling system and the cooling system of this embodiment. FIG. 3 is a plan view showing the cylinder block used in this embodiment, FIG. 4 is a sectional view taken along the line -- in FIG. 3, and FIG. 5 is a schematic diagram showing a conventional cooling device. 11... Engine body, 12... Cylinder block side water jacket, 13... Cylinder block, 14... Cylinder head side water jacket, 14a... Front end, 14b... Rear end, 15
...Cylinder head, 16...Communication hole, 17...
Water pump, 18...Radiator, 18a...
...Lower tank (lower part), 18b...Atsupa tank (upper part), 19...Cooling water introduction passage, 19a...
...one end, 19b...other end, 20...cooling water outlet passage, 20a...one end, 20b...other end.

Claims (1)

[Scope of utility model registration request] A first water jacket formed in the cylinder block, a second water jacket formed in the cylinder head, a communication passage for communicating the first and second water jackets, and one end thereof a cooling water introduction passage connected to the water pump side front end of the second water jacket and the other end connected to the lower part of the radiator; and one end connected to the rear end of the second water jacket. and a cooling water outlet passage whose other end is connected to the upper part of the radiator, and at least the engine cooling water that has flowed into the radiator from the cooling water outlet passage during normal operation of the engine is connected to the cooling water introduction passage. The engine cooling water in the second water jacket is constantly forcedly circulated through the passage through the second water jacket, while the engine cooling water is caused to naturally convect within the first water jacket through the communication passage. A cooling device for an internal combustion engine characterized by: