JPH0424119Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an engine cooling structure that increases the cooling efficiency in the vicinity of the exhaust port.

[Conventional technology]

In recent engines, the cross-sectional area of the intake port has been increased to increase charging efficiency, or multiple intake ports have been installed. Many of them are configured to be placed in In such an engine, there is almost no space left on the intake port side of the cylinder head, so in order to locate the ignition part of the spark plug in the center of the combustion chamber, the spark plug is placed in the exhaust gas, which has relatively free space. It is usually installed on the port side at an angle with respect to the cylinder axis.

By the way, with the engine configured as above,
Naturally, the distance between the spark plug and the exhaust port becomes very narrow. In the case of engines with multiple exhaust ports, the spacing between the exhaust ports and the spacing between the exhaust ports and the spark plug becomes even narrower. For this reason, the heat load that is applied to the exhaust port and the spark plug, between the exhaust ports, and the spark plug becomes extremely severe, and there is a risk that cracks may form in these parts or that the temperature of the spark plug may rise and cause this. Problems such as shortened lifespan arise.

In order to solve this problem, for example, as disclosed in Japanese Utility Model Application No. 58-14438, a small diameter cone-shaped cooling water passage is formed in the wall near the exhaust port of the cylinder head. Some engines are designed to flow cooling water through this cooling water passage to improve the cooling efficiency near the exhaust port of the cylinder head.

However, since both ends of the above cooling water passage are open water jackets, the pressure difference between both ends of the cooling water passage is low, and the diameter is small, so the circulation of cooling water in this cooling water passage is limited. is not very good, and the cooling effect cannot be obtained as much as expected.

On the other hand, in the structure disclosed in Japanese Utility Model Publication No. 54-9192, the outlet of the cooling water passage formed in the cylinder head is open to the water jacket of the cylinder head, and the inlet of the cooling water passage is
Cooling water is supplied from the water pump through an independent cooling water passage separate from that passing through the cylinder block water jacket. Therefore, the cooling water path from the water pump to the cylinder head water jacket via the above cooling water passage is the same as the cooling water path from the water pump to the cylinder head water jacket via the cylinder block water jacket. The cooling water in the water jacket of the cylinder head is returned to the water pump via the radiator.

[The problem that the idea aims to solve]

However, in the structure disclosed in Japanese Utility Model Publication No. 54-9129, the flow rate of cooling water in the cooling water passage of the cylinder head is increased compared to the structure disclosed in Japanese Utility Model Publication No. 58-14438. Although cooling efficiency is improved, the cooling water that flows out from the cooling water passage into the water jacket of the cylinder head returns to the water pump via the radiator, which acts as a resistance to the water flow. In this case, a very high pressure difference cannot be obtained. Therefore, this structure also has the problem that the vicinity of the exhaust port of the cylinder head cannot be sufficiently cooled.

Therefore, the engine cooling structure of the present invention utilizes a cone-shaped cooling water passage formed in the wall near the exhaust port to sufficiently increase the cooling efficiency near the exhaust port of the cylinder head. It is an object.

[Means to solve the problem]

In order to solve the above-mentioned problem, the engine cooling structure according to the present invention has a small-diameter, conical cooling water passage formed in the wall near the exhaust port of the cylinder head, and connects the engine's water jacket and radiator. In an engine cooling structure in which a water pump is provided in the cooling water path for circulating cooling water between the two, one end of the cooling water passage is open to the water jacket and the other end is bypassed. The cooling water path communicates with the radiator connection side of the water pump through the passage, and reaches the water pump from the water jacket through the above-mentioned cooling water passage and bypass passage. It is characterized by being installed in parallel with the cooling water path that reaches the pump.

[Effect]

According to the above configuration, one end of the cooling water passage of the cylinder head is open to the water jacket, and the other end is communicated via the bypass passage to the side of the water pump connected to the radiator, and the cooling water passage is connected from the water jacket to the water pump. The path of cooling water that reaches the water pump via the bypass passage is provided in parallel with the path of cooling water that reaches the water pump from the water jacket via the radiator. When the water is pumped in that direction, the radiator acts as a resistance to the water flow, creating negative pressure on the suction side of the water pump. At this time, since the outlet of the cooling water passage is connected to the suction side of the water pump via the bypass passage, the pressure difference between the front and rear of the cooling water passage in the cylinder head becomes sufficiently large. Therefore, the flow rate of cooling water in this cooling water passage can be ensured to be sufficient to cool the vicinity of the exhaust port of the cylinder head to a desired degree. On the other hand, when the water pump sends out cooling water toward the radiator, the radiator acts as a resistance to the water flow, resulting in high pressure on the discharge side of the water pump. This similarly increases the pressure difference between the front and rear of the cooling water passage of the cylinder head, which increases the pressure difference between the front and rear of this cooling water passage, and reduces the flow rate of cooling water in this cooling water passage to the area near the exhaust port of the cylinder head. can be ensured to be sufficiently cooled to the desired degree.

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Most of the cooling water for the engine 1 is supplied to the radiator 2.
The water is pumped through the water pump 3 to the water jacket 5 in the cylinder block 4, and is returned to the radiator 2 through the water jacket 7 in the head block 6. A part of the water flows from the water jacket 7 in the head block 6 to the bypass passage 8. The water is sucked into the water pump 3 via the radiator 2 without passing through the radiator 2. When the temperature of the cooling water is particularly low, the thermostat T shuts off the return flow path to the radiator 2, and all of the cooling water is sucked from the water jacket 7 to the water pump 3 via the bypass passage 8. .

A plurality of combustion chambers 9 are recessed in the lower surface of the headblock 6. Each combustion chamber 9 has two intake ports 10 on one side, two exhaust ports 11 on the other side, and an inclined spark plug hole 12 on the side on the exhaust port 11 side.
A V-shaped cone-shaped cooling water passage 14 is formed in the wall portion 13 of the head block 6 near the exhaust port 11. One end of this cooling water passage 14 is connected to the water jacket 5 of the cylinder block 4 through a communication hole 15 formed in the lower surface of the head block 6.
The other end is a manifold-shaped bypass passage 1 recessed in the lower surface of the head block 6.
6 is connected. The other end of the bypass passage 16 is connected to a bypass passage 8 that directly connects the water jacket 7 of the head block 6 and the water pump 3. Therefore, the other end of the cooling water passage 14 is communicated via the bypass passages 16 and 8 with the suction side of the water pump 3, that is, the side of the water pump 3 connected to the radiator 2.

Therefore, the water jacket 5 of the cylinder block 4 is connected to the cooling water passage 14 and the bypass passage 1.
The path of the cooling water that reaches the water pump 3 via the water jackets 6 and 8 is provided in parallel with the path of the cooling water that reaches the water pump 3 from the water jacket 5 through the water jacket 7 and the radiator 2.

In the above configuration, when the water pump 3 sends cooling water toward the water jacket 5 of the cylinder block 4, the radiator 2 acts as a resistance to the water flow, and negative pressure is generated on the suction side of the water pump 3. In this case, the outlet of the cooling water passage 14 of the head block 6 is connected to the bypass passages 16 and 8.
Since it is connected to the suction side of the water pump 3 via the cooling water passage 14, the pressure difference between the front and rear of the cooling water passage 14 becomes sufficiently large. Therefore, this cooling water passage 1
The flow rate of the cooling water at 4 is sufficient to cool the vicinity of the exhaust port 11 of the headblock 6 to a desired degree.

At this time, a part of the cooling water in the water jacket 5 of the cylinder block 4 is sucked into the cooling water passage 14 through the communication hole 15 by the suction force of the water pump 3, and while passing through the cooling water passage 14, The water cools the wall portion 13 and is forced to flow to the suction side of the water pump 3 through the bypass passage 16 and the bypass passage 8.

On the other hand, if the water pump 3 sends the cooling water in the opposite direction to the radiator 2, the radiator 2 becomes a resistance to the water flow, and the discharge side of the water pump 3, that is, the side connected to the radiator 2, becomes high pressure. . This similarly increases the pressure difference between the front and rear of the cooling water passage 14 of the headblock 6, and the flow rate of the cooling water in the cooling water passage 14 is adjusted so that the vicinity of the exhaust port 11 of the headblock 6 is cooled to the desired degree. You can ensure that you have enough.

[Embodiment 2] The present invention is applicable not only to the above-mentioned four-valve engine but also to a so-called three-valve engine having two intake ports 10 and one exhaust port 11, as shown in FIG. 5, for example.

In the embodiment shown in FIG. 5, the cooling water passage 14 formed in the wall portion 13 near the exhaust port 11 is formed in a straight line, and one end thereof is open to the water jacket 7 in the head block 6. has been done. The cooling water path that reaches the water pump 3 from the water jacket 7 of the head block 6 via the cooling water passage 14 and the bypass passages 16 and 8 is the cooling water path that reaches the water pump 3 via the water jacket 7 and the radiator 2. It is installed in parallel with the water path. The other configurations are the same as those of the previous embodiment, and the effects obtained are also the same as those of the previous embodiment.

[Embodiment 3] When opening one end of the cooling water passage 14 to the water jacket 7 in the head block 6, for example, as shown in FIGS. 6a and 6b, the flow of cooling water into the cooling water passage 14 is guided. Guide ribs 17 may be formed in the water jacket 7.

In this case, since the flow of cooling water is smoothly guided into the cooling water passage 14 by the guide rib 17, the flow within the cooling water passage 14 becomes even better, and the wall portion 13 near the exhaust port 11 is cooled. Efficiency can be further increased.

[Effect of idea]

The engine cooling structure of this invention is as described above.
One end of the cooling water passage of the cylinder head is open to the water jacket, and the other end is communicated via a bypass passage to the side of the water pump connected to the radiator. The cooling water path from the water jacket to the water pump is arranged in parallel with the cooling water path from the water jacket to the water pump via the radiator.

Therefore, the pressure difference between the front and rear of the cooling water passage of the cylinder head can be made sufficiently large.
By ensuring a necessary flow rate of cooling water in the cooling water passage, the cooling efficiency of the wall near the exhaust port can be sufficiently increased. As a result, it is possible to eliminate the risk of cracks occurring in the vicinity of the exhaust port and the risk of overheating of the ignition plug, and also has the effect of reducing the heat load on the ignition plug and extending the life of the ignition plug. play.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram conceptually showing an embodiment of the present invention, Fig. 2 is a bottom view of the cylinder head, and Fig. 3 is a schematic diagram conceptually showing an embodiment of the present invention.
The figure is a sectional view taken along the line A-A in Fig. 2, and Fig. 4 is a cross-sectional view taken along the line A-A in Fig. 3.
5 is a cross-sectional plan view of a main part of another embodiment of the present invention, FIG. 6a is a longitudinal sectional view of a main part of still another embodiment of the present invention, and FIG. C- in Figure 6a
It is a sectional view taken along line C. 2 is a radiator, 3 is a water pump, 6 is a head block, 5 is a water jacket, 7 is a water jacket, 8 is a bypass passage, 11 is an exhaust port, 14 is a cooling water passage, and 16 is a bypass passage.

Claims (1)

[Claim for Utility Model Registration] A small-diameter, cone-shaped cooling water passage is formed in the wall near the exhaust port of the cylinder head, and the cooling water passage between the engine's water jacket and the radiator is provided between the two. In an engine cooling structure that is provided with a water pump for circulating cooling water, one end of the cooling water passage is open to the water jacket, and the other end is connected to the radiator in the water pump via a bypass passage. A cooling water path that communicates with the water jacket and reaches the water pump via the above-mentioned cooling water passage and bypass passage is provided in parallel with a cooling water path that reaches the water pump from the water jacket through the radiator. An engine cooling structure characterized by: