JP3086929B2 - Engine cooling structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cooling structure.

[0002]

2. Description of the Related Art In a liquid-cooled engine, a water jacket is generally provided around a bore of a cylinder block. However, if the water jacket surrounding the bore is formed as an integral structure, the cooling performance will be excessive or insufficient depending on the location, causing a problem that the low-temperature portion is overcooled or the temperature of the high-temperature portion becomes too high. In view of the above, there has been conventionally proposed a device in which the cooling performance is changed between a high-temperature portion and a low-temperature portion. For example, Shokai 6
In the cooling structure of an engine described in Japanese Patent Application Laid-Open No. 2-28021, separate refrigerant passages are provided for the upper portion of the bore where the temperature is high and the lower portion of the bore where the temperature is low, and the high temperature portion suppresses the rise of the maximum temperature by a large amount of refrigerant. In the low temperature part, a small amount of refrigerant is allowed to flow to prevent overcooling.

[0003] The demand for the cooling performance of the engine also changes depending on the operating conditions. For example, it is necessary to keep the refrigerant temperature at a relatively low temperature to prevent the engine from overheating at a high load, and to increase the refrigerant temperature at a relatively low load. In order to prevent the emission of harmful components such as unburned gas while maintaining the temperature, it has been customary to control the refrigerant temperature using a thermostat. For example, in Japanese Patent Publication No. 54-9665, the combination of two thermostats with different temperature settings and a valve that closes at low load and opens at high load keeps the refrigerant temperature high at low load and low at high load. I try to keep it.

[0004]

The prior art discloses that since the engine has a high temperature part and a low temperature part as described above, it is necessary to change the cooling performance according to each part. It is disclosed that the cooling performance is changed according to conditions. By the way, in the cylinder block of the engine, the temperature of the bore portion increases on the exhaust side, and the temperature of the bore portion decreases on the intake side. Therefore, separate water jackets are provided on the exhaust side and the intake side, respectively. It is desirable to configure the cooling system so that the supply of the cooling water can be controlled independently. In this case, for example, it is advantageous to flow cooling water exclusively to the exhaust side at the time of a cold start in order to improve the warming-up efficiency. Need to be improved. However, in order to separately control the supply of the cooling water on the intake side and the exhaust side in this way, the layout of the cooling water passages and the like and the arrangement of the thermostat and the like become complicated, and a compact cooling structure cannot be achieved. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a compact engine cooling structure capable of improving both warm-up efficiency at low temperatures and cooling performance at high temperatures. With the goal.

[0006]

SUMMARY OF THE INVENTION According to the present invention, in an engine having a cooling chamber in each of a cooling section on an intake side and an exhaust side, a pump for circulating a refrigerant is provided in a refrigerant passage communicating with a discharge port of a radiator. A return passage for branching the downstream of the pump into a first branch passage leading to a cooling chamber on the intake side and a second branch passage leading to a cooling chamber on the exhaust side, and for circulating a refrigerant cooled in each cooling part to a radiator. And a first bypass passage for returning the refrigerant circulating in each cooling chamber to the upstream of the pump by bypassing the radiator, and bypassing the refrigerant sent to the first branch passage to the cooling chamber on the intake side. A second bypass passage returning to the upstream of the pump is provided, and a flow of the refrigerant circulating through the pump is operated at a first temperature set at a relatively high temperature on the upstream side of the pump. In the low temperature side of the first thermostat to switch to a 閉循 ring through the radiator is provided at the high temperature side and 閉循 ring which bypasses the radiator, further, the first branch passage, the is set to a relatively low temperature side 2
Operating at the set temperature of the refrigerant, the refrigerant sent to the branch passage is closed circulation through the second bypass passage on the low temperature side and closed circulation through the cooling chamber on the intake side on the high temperature side. By providing the second thermostat for switching the flow, a compact cooling structure is realized.

According to the present invention, the intake gallery and the exhaust gallery are provided with refrigerant gallery extending in the longitudinal direction of the engine, and the refrigerant is supplied to the intake and exhaust side cooling units via the respective refrigerant galleries. .

[0008]

When the refrigerant temperature is lower than the second set temperature set on the low temperature side during cold start or the like, the first thermostat operating at the first set temperature on the high temperature side controls the flow of the refrigerant by the radiator. The second thermostat that operates at the second set temperature and performs the closed circulation to bypass the refrigerant sent to the first branch passage downstream of the pump and bypasses the cooling chamber on the intake side to the second bypass passage. Shed. At this time, the refrigerant is sent to the cooling chamber on the exhaust side via the second branch passage branched from the downstream side of the pump in the refrigerant passage. The refrigerant sent to the exhaust side is a part of the pump discharge amount, and while cooling the exhaust side appropriately, the refrigerant itself is heated and circulates upstream of the pump together with the refrigerant flowing through the first bypass passage. As a result, the temperature of the refrigerant itself quickly rises without excessive cooling of the engine, and warm-up is promoted.

Next, when the warm-up is completed and the refrigerant temperature reaches the second set temperature, if the temperature is still lower than the first set temperature, the first thermostat causes the flow of the refrigerant to close the circulation without passing through the radiator. On the other hand, the second thermostat switches the circulation path so as to form a closed circulation through the cooling chamber on the intake side. Thereby, the refrigerant is sent to the cooling chamber on the exhaust side via the second branch passage, and also sent to the cooling chamber on the intake side via the first branch passage. Cooled efficiently.

When the refrigerant temperature rises to the first set temperature, for example, when the load is high, the flow of the refrigerant is switched to the closed circulation through the radiator by the first thermostat. The rise is suppressed.

Further, according to the structure of the present invention, the arrangement of the refrigerant passage and the thermostat for separately controlling the supply of the refrigerant on the intake side and the exhaust side is simplified, and the cooling structure is compact. Become. In particular, when the gallery for the refrigerant is provided on the intake side and the exhaust side, the arrangement of the refrigerant passage and the like and the arrangement of the thermostat and the like are further simplified, and a very compact cooling structure can be obtained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 are explanatory views for explaining the structure and operation of one embodiment of the present invention. In this embodiment, the cylinder block 2 of the engine 1 has an intake side, that is, the same side as the intake port 4 formed in the cylinder head 3, and an exhaust side, that is, an exhaust port 5 of the cylinder head 3.
Water rails (gallery) 6, 7 extending in the longitudinal direction of the engine are formed on the same side as. Also,
In the cylinder block 2, around the bore 2a of each cylinder,
Water jackets 8, 9 on the intake side and the exhaust side, which are independent from each other, are formed.
7, respectively. Each of the water rails 6 and 7 communicates with a water jacket 12 in the cylinder head 3 at the upper end.

The water rails on the intake and exhaust sides 6,
The cooling circuit that supplies the cooling water to the cooling water passage 7 includes a cooling water passage 14 that communicates with a discharge port of the radiator 13, a water pump 15 disposed in the cooling water passage 14, and a water pump 15.
A first branch passage 16 branching off from the cooling water passage 14 downstream of the cooling water passage 14 and leading to the water rail 6 on the intake side, and a water branch 7 branching off from the cooling water passage 14 downstream of the water pump 15 to the water rail 7 on the exhaust side. Second branch passage 17 leading to
A return passage 18 that returns the cooling water from the water jacket 12 in the cylinder head 3 to the radiator 13, a first bypass passage 19 that branches off from the return passage 18 and bypasses the radiator 13 and communicates upstream of the water pump 15. A second bypass passage 20 branching from the middle of the first branch passage 16 branched from the downstream of the water pump 15 and communicating with the first bypass passage 19; The radiator 13 operates at a first set temperature (for example, 113 ° C.) set on the side of the radiator 13, and when the set temperature is not reached, the radiator 13 is closed and the water pump 15
A first thermostat 21 that circulates cooling water directly to the radiator 13 by closing the first bypass passage 19 at a temperature equal to or higher than the set temperature, and a relatively low temperature side in the first branch passage 16. It operates at the set second set temperature (for example, 88 ° C.), and when the set temperature is not reached, the flow to the water rail 6 on the intake side is cut off and the cooling water flows to the second bypass passage 20. When the temperature is equal to or higher than the set temperature, the second thermostat 22 is configured to close the second bypass passage 20 and circulate the cooling water to the water rail 6 on the intake side.

At the time of a cold start or the like, the temperature of the cooling
The flow of the cooling water when the temperature is lower than the set temperature is as shown by the solid line in FIG. In this state, the second thermostat 22 shuts off the flow of the cooling water to the water rail 6 on the intake side, and returns the cooling water sent to the first branch passage 16 through the second bypass passage 20. . On the other hand, cooling water is supplied to the water rail 7 on the exhaust side via the second branch passage 17. Cooling water is supplied from the water rail 7 on the exhaust side to the water jacket 9 on the exhaust side of each cylinder, and is sent to the water jacket 12 in the cylinder head 3. The first thermostat 21 closes the radiator 13 side and opens the first bypass passage 19 side. Therefore, the cooling water returning from the water jacket 12 in the cylinder head 3 flows directly upstream of the water pump 15 without passing through the radiator 13. As a result, the exhaust side is appropriately cooled by a part of the cooling water discharged from the water pump 15, and the cooling water itself is heated and flows through the return passage 18 to the first bypass passage 19, and the second The coolant merges with the cooling water flowing through the bypass passage 20 and is returned upstream of the water pump 15. As a result, the temperature of the refrigerant itself quickly rises without excessive cooling of the engine, and warm-up is promoted.

Next, when the warm-up is completed and the refrigerant temperature reaches the second set temperature, the flow of the cooling water becomes as shown in FIG. That is, the second thermostat 22 closes the second bypass passage 20 and circulates the cooling water to the water rail 6 on the intake side. Thereby, the cooling water is also sent to the intake side via the first branch passage 16, and both the exhaust side and the intake side are cooled. At this time, the temperature of the cooling water
If the temperature is lower than the set temperature, the first thermostat 21 remains closed on the radiator 13 side, and the returning cooling water is returned to the upstream of the water pump 15 via the first bypass passage 19.

FIG. 3 shows the flow of the cooling water when the temperature of the cooling water rises to the first set temperature under a high load or the like. In this case, the first thermostat 21 opens the radiator 13 side, whereby the cooling water circulates through the radiator 13 and returns to the water pump 15. Accordingly, an excessive rise in the temperature of the cooling water is suppressed.

According to such a circuit configuration, even when the second thermostat 22 opens the second bypass passage 20, a part of the cooling water that is heated and returned returns through the second bypass passage 20 as it is. Since the cooling water merges with the returning cooling water and circulates upstream of the water pump 15, the first thermostat 21 can correctly detect the temperature of the cooling water as a whole. Further, according to such a configuration, when the first thermostat 21 closes the radiator 13, the cooling water returning via the first bypass passage 19 cancels the pulsation of the cooling water acting from the radiator 13 side. The first thermostat 21 can be prevented from fluttering due to the pulsation of the cooling water.

[0019]

As described above, the present invention is configured as described above, so that the engine cooling structure that achieves both improvement in warm-up efficiency at low temperatures and improvement in cooling at high temperatures can be formed compactly.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram (part 1) for explaining the structure and operation of an embodiment of the present invention;

FIG. 2 is a view for explaining the structure and operation of one embodiment of the present invention (part 2);

FIG. 3 is an explanatory view (part 3) for explaining the structure and operation of one embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 engine 2 cylinder block 3 cylinder head 4 intake port 5 exhaust port 6 water rail (intake side) 7 water rail (exhaust side) 8 water jacket (intake side) 9 water jacket (exhaust side) 13 radiator 14 cooling water passage 15 water Pump 16 First branch passage 17 Second branch passage 19 First bypass passage 20 Second bypass passage 21 First thermostat 22 Second thermostat

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01P 7/16 502 F01P 7/16 505 F01P 3/02 F02F 1/36

Claims (2)

(57) [Claims] In an engine having a cooling chamber in each of a cooling section on an intake side and an exhaust side, a pump for circulating a refrigerant is disposed in a refrigerant passage communicating with a discharge port of a radiator, and a downstream of the pump is cooled on an intake side. A first branch passage leading to the chamber and a second branch passage leading to the cooling chamber on the exhaust side are branched, and a return passage is provided for circulating the refrigerant that has cooled each cooling part to the radiator. A first bypass passage for returning the circulated refrigerant to the upstream of the pump by bypassing the radiator, and a refrigerant sent to the first branch passage to the upstream of the pump by bypassing the cooling chamber on the intake side. A second bypass passage for returning the refrigerant, and operating at a first set temperature which is set on a relatively high temperature side upstream of the pump so as to reduce the flow of the refrigerant circulating through the pump to the set temperature. On the low temperature side, a first thermostat is provided for switching to a closed circulation bypassing the radiator, and on a high temperature side, a first thermostat for switching to a closed circulation via the radiator is provided. Operating at a set temperature of 2, the refrigerant sent to the branch passage is closed circulation through the second bypass passage at a low temperature side of the set temperature and closed circulation through the intake side cooling chamber at a high temperature side. An engine cooling structure comprising a second thermostat for switching a flow of a refrigerant so as to perform a cooling operation. 2. The engine according to claim 1, further comprising a refrigerant gallery extending in the engine longitudinal direction on the intake side and the exhaust side, and supplying the refrigerant to the intake side and exhaust side cooling units via the respective refrigerant galleries. Cooling structure.