JPH06101474A - Cooling device of internal combustion engine - Google Patents

Abstract

PURPOSE:To make security of heater performance at the time cooling and emphatical cooling of the side of a cylinder head immediately after warming up compatible with each other. CONSTITUTION:A water jacket 6 on the cylinder head side and a water jacket 7 on the cylinder block side are mutually separated, and a water pump 9 is arranged at the rear end part so that cooling water is fed from the water jacket 6 on the cylinder head side to the water jacket 7 on the cylinder block side. A passage 13 for a heater is provided along a distance from the vicinity of a pump exit to the front end part of the water jacket 6 on the cylinder head side. A radiator 15 is provided between the front end part of the water jacket 7 on the cylinder block side and the front end part of the water jacket 6 on the cylinder head side, and a thermostat 18 is interposed in a connection part toward the water jacket 6 at the cylinder head side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water cooling type cooling device for an internal combustion engine, and more particularly to an improvement of a cooling device which positively cools the cylinder head side by forcedly circulating cooling water.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine, in order to prevent abnormal combustion such as knocking, the temperature on the cylinder head side is made relatively low, and in order to reduce friction due to the viscosity of lubricating oil, a cylinder block is used. It is desirable to keep the side temperature relatively high. Further, in a general vehicle internal combustion engine in which engine cooling water is used as a heat source of a vehicle heater, it is necessary to secure the heat quantity of the heater as early as possible after starting.

In consideration of such a point, JP-A-54-20
In Japanese Patent Publication No. 248, as shown in FIG. 5, the water pump 3 is provided at the front end of the water jacket 31 on the cylinder head side.
2, the cooling water is guided from the front end of the water jacket 33 on the cylinder block side to the radiator 35 via the thermostat 34, and the outlet side of the radiator 35 is communicated with the suction side of the water pump 32. The heater core 36 extends from the front end of the water jacket 31 to the suction side of the water pump 32.
There is disclosed a cooling device having a heater passage 37 provided therein. The water jacket 31 on the cylinder head side and the water jacket 33 on the cylinder block side communicate with each other through a large number of water holes 38. In this case, at a low temperature when the thermostat 34 is closed, the cooling water circulates only between the cylinder head side water jacket 31 and the heater passage 37, so that the heater rises quickly. And after warming up, radiator 35
The cooling water also circulates to the cylinder head side water jacket 31.
As it flows into the cylinder 3, the cylinder head side is cooled more strongly.

[0004]

However, in the above-mentioned conventional configuration, the water jacket 31 on the cylinder head side is provided.
Since the cylinder block water jacket 33 and the cylinder block side water jacket 33 communicate with each other through the water hole 38, even if the cooling water is allowed to flow only to the cylinder head side water jacket 31 side at a low temperature, the cylinder block passes through the water hole 38. The cooling water also flows into the side water jacket 33,
There is a problem that the temperature rise of the cooling water toward the heater core 36 is hindered.

Further, since the water jacket 31 on the cylinder head side is located immediately after the discharge of the water pump 32,
The pressure in the water jacket 31 on the cylinder head side becomes relatively high. Therefore, the cooling due to subcool boiling cannot be effectively used in the high heat load region, and the heat spot cannot be eliminated.

[0006]

SUMMARY OF THE INVENTION A cooling device for an internal combustion engine according to the present invention includes a cylinder head side water jacket and a cylinder block side water jacket, which are formed separately from each other, one end portion of the cylinder head side water jacket, and a cylinder. A water pump located between one end of the block-side water jacket and pumping cooling water from the cylinder head side to the cylinder block side, and one end connected to the water pump outlet of the cylinder block-side water jacket and the other end A passage for a heater connected to the other end of the cylinder head side water jacket, a radiator disposed between the other end of the cylinder head side water jacket and the other end of the cylinder block side water jacket, and the radiator. Outlet side and cylinder head side It is characterized in that a interposed thermostat between O over data jacket.

[0007]

[Function] Since the thermostat is closed when cold, the connection with the radiator is cut off. The cooling water circulates in the order of water jacket on the cylinder head side → water pump → passage for heater → water jacket on the cylinder head side. That is, the cooling water which has received heat in the water jacket on the cylinder head side flows into the heater passage without being mixed with the cylinder block side, and the heat quantity of the heater can be secured at an early stage.

After completion of warming up, the thermostat opens. For this reason, the cooling water is cooled by the water jacket on the cylinder head side →
It circulates from the water pump → the water jacket on the cylinder block side → the radiator → the water jacket on the cylinder head side. A part of the cooling water flows from the water pump to the heater passage to the cylinder head side water jacket. That is, the cooling water radiated by the radiator first flows through the water jacket on the cylinder head side and then goes to the water jacket on the cylinder block side, so that the cylinder head side is positively cooled. Further, since the water jacket on the cylinder head side is on the suction side of the water pump, the pressure becomes low, and efficient cooling by subcool boiling becomes active.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an in-line four-cylinder internal combustion engine 1 according to the present invention.
1 shows an embodiment applied to. This internal combustion engine 1
It has a cylinder head 2 and a cylinder block 3, and an oil pan 4 is attached to its lower surface,
The transmission 5 is attached to the rear end. A cylinder head side water jacket 6 is formed inside the cylinder head 2 so as to cover the periphery of the fuel chamber. A cylinder block side water jacket 7 is formed inside the cylinder block 3 so as to surround the cylinder bore. The cylinder head side water jacket 6 and the cylinder block side water jacket 7 are partitioned by a partition wall 8 and are separated and independent from each other.

The water pump 9 is attached to the rear end portion of the cylinder head 2, and its suction port 9a is opened to the cylinder head side water jacket 6 and the downwardly extending discharge port 9b is connected to the cylinder block side water jacket. It communicates with the rear end of the jacket 7. The water pump 9 is driven by a camshaft 12 via gears 10 and 11.

The heater passage 13 has an inlet end 13a.
Is opened at the rear end of the cylinder block side water jacket 7, more specifically, in the vicinity of the discharge port 9b of the water pump 9, and the outlet side end 13b communicates with the front end of the cylinder head side water jacket 6. And
A heater core 14 for heating the passenger compartment is provided in the middle of the passage.

Further, the radiator 15 is an upper tank 15
The upper tank 15a is connected to the front end of the cylinder head side water jacket 6 via the upper passage 16 and the lower tank 15b is connected to the cylinder block side water jacket via the lower passage 17. 7 is connected to the front end. A thermostat 18 is provided at a connecting portion between the upper passage 16 and the water jacket 6 on the cylinder head side to shut off the two when the temperature is low. A radiator cap 19 having a pressurizing valve is attached to the upper tank 15a, and a reservoir tank 20 is connected via the radiator cap 19.

Next, the operation of the above embodiment will be described.

When the temperature of the cooling water is low such as immediately after the start of the internal combustion engine 1, the thermostat 18 is closed and the communication between the water jacket 6 on the cylinder head side and the radiator 15 is cut off. Therefore, with the operation of the water pump 9, the cooling water flows from the cylinder head side water jacket 6 → the water pump 9 → the heater passage 13 (heater core 14) → the cylinder head side water jacket 6 as shown by the arrow in FIG. To circulate. That is, the cooling water does not flow through the water jacket 7 on the cylinder block side, and the entire amount of the cooling water heated by the water jacket 6 on the cylinder head side goes to the heater core 14. For this reason, the heating performance is improved in cold regions. On the cylinder block 3 side, the rise of the cylinder bore wall temperature is promoted. This improves fuel economy and exhaust performance. In particular, since the cylinder head side water jacket 6 and the cylinder block side water jacket 7 are completely separated from each other, heat transfer between them is suppressed, and the above effect can be obtained more reliably.

When the warm-up of the internal combustion engine 1 is completed and the cooling water temperature reaches a predetermined temperature, the thermostat 18 opens. In this state, as shown by the arrow in FIG. 3, the cooling water is cylinder head side water jacket 6 → water pump 9 → cylinder block side water jacket 7 → lower passage 17 → radiator 15 → upper passage 16 → thermostat 18 →
It circulates like the water jacket 6 on the cylinder head side. Further, a part of the cooling water flows in the order of the water pump 9 → the heater passage 13 (heater core 14) → the cylinder head side water jacket 6, whereby a heat quantity for heating is secured.

According to the flow path in the warmed-up state, the cooling water radiated by the radiator 15 and having a relatively low temperature first flows in the water jacket 6 on the cylinder head side, so that the cylinder head 2 side is positively cooled. . Then, since the relatively high temperature cooling water that has passed through the cylinder head side water jacket 6 travels to the cylinder block side water jacket 7, excessive cooling of the cylinder block 3 side is prevented.

Further, in the above structure, since the cylinder head side water jacket 6 is located immediately before the water pump 9, the pressure of the cooling water in the cylinder head side water jacket 6 becomes low, and the cooling by subcool boiling is promoted. . FIG. 4 shows the relationship between the combustion chamber wall temperature, the water jacket side heat transfer coefficient, and the boiling heat transfer contribution rate (ratio of boiling heat transfer to heat transfer), with the subcool degree when the cooling water temperature is 100 ° C. as the horizontal axis. Is shown. still,
The subcooling degree is the difference between the cooling water temperature and the saturation temperature (boiling temperature) at that pressure, and the lower the pressure, the smaller the subcooling degree and the more easily boiling occurs. In other words, subcool boiling becomes active. As is clear from this figure, when the subcooling degree becomes smaller and the subcooling boiling becomes more active as the pressure decreases, the heat transfer coefficient improves as compared to the area where the subcooling degree is large in which the contribution ratio of forced convection heat transfer is high and the wall The temperature drops significantly. Subcool boiling also depends on the heat load, and even with the same degree of subcool, the larger the heat flux, the more active the subcool boiling. That is, in a place with a high heat load, such as between exhaust valves of the combustion chamber of the cylinder head 2,
Even with the same degree of subcooling, boiling will occur first, and efficient cooling with a high heat transfer coefficient can be performed.

Therefore, in the above structure, by lowering the pressure in the water jacket 6 on the cylinder head side, the subcooled boiling efficiently cools a portion having a high heat load, and the occurrence of hot spots is suppressed. Further, as described above, the portion having a low heat load is cooled by the forced convection of the low temperature cooling water, so that the temperature can be kept low as a whole.

Incidentally, since the water pump 9 is located downstream of the water jacket 6 on the cylinder head side, cavitation of the pump may occur. For example, in the conventional example shown in FIG. 5, the radiator cap maintains a predetermined pressure. 35 from the upper tank 35a to the core portion 35b
After being passed through, the water pump 32 is sucked in, and since the passage resistance in the core portion 35b is large, the pressure at the pump inlet portion is considerably low. On the other hand, in the configuration of the above embodiment, the upper tank 15 which is kept at a predetermined pressure is used.
Since the cooling water is sucked from a into the water pump 9 via the thermostat 18 and the cylinder head side water jacket 6 without passing through the core portion 15b, the pressure drop is rather small. Therefore, even if the temperature rise at the pump inlet is taken into consideration, the cavitation resistance of the pump does not deteriorate.

[0021]

As is apparent from the above description, according to the cooling device for an internal combustion engine of the present invention, the cooling water heated by the water jacket on the cylinder head side is cooled by the cooling water on the cylinder block side when the engine temperature is low. It can be circulated to the heater core without being mixed with, and the heating performance can be improved well, and the rise of the cylinder bore wall temperature can be promoted. Further, after warming up, the cylinder head side can be intensively cooled to keep it at a low temperature, and the supercooling of the cylinder block side can be prevented. In particular, the pressure in the water jacket on the cylinder head side can be lowered to promote subcool boiling, and local hot spots can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of a cooling device according to the present invention.

FIG. 2 is an explanatory view showing the flow of cooling water when the engine is cold.

FIG. 3 is an explanatory diagram showing a flow of cooling water after completion of warming up.

FIG. 4 is a characteristic diagram showing a relationship between a subcool degree and a combustion chamber wall temperature and the like.

FIG. 5 is a structural explanatory view showing an example of a conventional cooling device.

[Explanation of symbols]

 6 ... Cylinder head side water jacket 7 ... Cylinder block side water jacket 9 ... Water pump 13 ... Heater passage 14 ... Heater core 15 ... Radiator 18 ... Thermostat

Claims (1)

[Claims] 1. A cylinder head-side water jacket and a cylinder block-side water jacket formed separately from each other, and a cylinder head located between one end of the cylinder head-side water jacket and one end of the cylinder block-side water jacket. Pump for sending cooling water from the cylinder side to the cylinder block side, and a heater with one end connected near the water pump outlet of the cylinder block side water jacket and the other end connected to the other end of the cylinder head side water jacket A passage, a radiator disposed between the other end of the water jacket on the cylinder head side and the other end of the water jacket on the cylinder block side, and interposed between the outlet side of the radiator and the water jacket on the cylinder head side. With a thermostat A cooling device for an internal combustion engine, comprising: