JPS63147918A - Evaporative cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a local cooling failure from occurring, by connecting a vapor phase part of a water jacket to a condenser, while connecting a liquid phase part to a radiator via a pump, and giving a forced convection to a pyrogenetic load part, in case of an evaporative cooling device. CONSTITUTION:In the water jacket 2 formed as one body over both of a cylinder block 3 and a cylinder head 4, there are formed with a vapor phase refrigerant area in the upper part and a liquid phase refrigerant area in the lower part respectively. This vapor phase refrigerant area is connected to a condenser via a steam outlet 5 and a steam manifold 7, and the condensed refrigerant hereat is connected to a radiator outlet passage 21 via a first solenoid valve 15. As for the liquid phase refrigerant area, it is connected with a liquid phase refrigerant cooling system consisting of a radiator inlet passage 19, a radiator 20, a bypass passage 23 and a thermostat valve 24, thus it is designed to as to be given a forced convection by a circulating pump 22.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improvement in a boiling cooling system for an internal combustion engine, which cools various parts of the engine mainly through a boiling and condensing cycle of a refrigerant.

BACKGROUND OF THE INVENTION The present applicant forms a closed-loop refrigerant circulation system mainly consisting of a water jacket of an internal combustion engine, a condenser, and a refrigerant supply pump, and stores liquid phase refrigerant at a predetermined level in the water jacket.・In addition to cooling each part of the engine through boiling vaporization, the refrigerant vapor generated in the overjacket is led to the condenser and condensed, and then restarted by the intermittent operation of the refrigerant supply pump based on the detection of the liquid level sensor. Various boiling cooling devices have been proposed that supply water to the jacket (for example, Japanese Patent Laid-Open No. 60-3
6712, JP-A-60-36715, etc.)
. In this evaporative cooling device, active forced convection is not applied to the liquid phase refrigerant within the water jacket. That is, the form of boiling is natural convection boiling, so-called pool boiling, which involves only flow due to bubbles. According to this heat transfer accompanied by boiling, it is possible to secure a very high heat transfer coefficient between the heat transfer surface such as a shilling head and the refrigerant in the region of nucleate boiling 1@, and it is possible to achieve a uniform and effective heat transfer rate. Cooling can be performed.

Problems to be Solved by the Invention The water jacket of an internal combustion engine, in which liquid-phase refrigerant is stored, has a fairly complex structure, and there are particularly narrow restrictions around the valve seat of the cylinder head, between boats, or between litchis in the cylinder block. It becomes space. If the cylinder block has a Siamese structure, thin drill holes are used as water jackets between the litchis, resulting in a very narrow space.

Boiling characteristics in such narrow confined spaces generally exhibit very high heat transfer coefficients because the vigorous movement of the rising bubbles keeps the boundary layer thin compared to the case of wide space conditions. However, in the high heat flux region, the supply of liquid phase refrigerant to the heat transfer surface is inhibited by the more rapid rise of bubbles, and the time that the heat transfer surface is covered with vapor bubbles becomes longer. The heat transfer coefficient decreases. In other words, boiling in a narrow confined space shows a tendency for the limit of nucleate boiling to shift to a lower heat flow velocity side. Therefore, in a small high-output engine in which it is difficult to expand the water jacket, there is a risk that cooling may occur in restricted spaces such as around the exhaust port or around the exhaust valve and where the heat load is high.

Means for Solving the Problems In order to solve the above problems, the present invention forcibly circulates the liquid phase refrigerant in the water jacket between the radiator and the high heat load areas such as around the exhaust port. It is designed to provide convection.

That is, the boiling cooling device for an internal combustion engine according to the present invention has the following features:
A water jacket in which liquid phase refrigerant is stored to an appropriate level and whose upper space is a vapor phase refrigerant region, a condenser that condenses the refrigerant vapor taken out from the upper part of this water jacket, and the liquid phase refrigerant condensed in this condenser. a radiator that cools the liquid refrigerant taken out from the water jacket, and a refrigerant circulation means that constantly circulates the liquid refrigerant between the radiator and the upper water jacket. and is characterized in that the refrigerant circulation means is configured to apply forced convection to a high heat load section within the water jacket by means of a flow of the filtrated liquid phase refrigerant.

The liquid phase refrigerant existing in the working water jacket receives combustion heat and reaches approximately the saturation temperature, causing boiling and cooling various parts. The refrigerant vapor generated here is condensed in the condenser and then returned to the water jacket by the refrigerant supply means.

On the other hand, the liquid phase refrigerant taken out from the water jacket by the refrigerant circulation means passes through the radiator and is subcooled before being sent back to the water jacket. , which provides forced convection to the high heat load areas within the water jacket. Therefore, the liquid phase refrigerant is reliably supplied to the heat transfer surface of the high heat load section, and the high heat flow embodiment is shown in FIG. 1 is an internal combustion engine, and 2 is a water jacket provided inside the internal combustion engine.

The water jacket 2 covers the cylinder block 3 and cylinder head 4 so as to cover the cylinder and the combustion chamber.
Since the upper part, which is normally a gas phase refrigerant area, is in communication with each cylinder, a plurality of vapor outlets 5 are formed at appropriate positions in the upper part. has been done.

This 7.4 air outlet 5 communicates with the upper part of the condenser 8 via a steam manifold 6 and a steam passage 7.

The above-mentioned condenser 8 is installed at a position such as on the side of the vehicle where it can receive the vehicle running wind, and is equipped with an electric cooling fan 9 for forced cooling on the front side and the back side of the condenser 8. The configuration is such that the temperature detected by the temperature sensor 10 provided in the lower tank 8 forcibly cools the tank 8. Further, a reservoir tank 11 is connected to a lower tank below the condenser 8 in which the refrigerant condensed in the condenser 8 is collected. The upper space of this reservoir tank 11 is open to the atmosphere via the atmosphere communication passage 12, so it can be turned on or off depending on the presence or absence of liquid phase refrigerant at a predetermined level.
A liquid level sensor 13 that emits an FF signal is attached. A refrigerant supply passage 1 is provided at the bottom of the reservoir tank 11.
4 is connected to the refrigerant supply passage 14 in parentheses.
A first electromagnetic valve 15 that opens and closes in conjunction with a detection signal from the liquid level sensor 13 is interposed therein. A normally open second electromagnetic valve 16 is interposed in the atmospheric communication passage 12 of the reservoir tank 11 to prevent refrigerant vapor from blowing out. This second solenoid valve 16 is controlled to open and close based on the detection signal of the temperature sensor 10 of the capacitor 8.
It is configured to close when the temperature exceeds a set temperature set near the saturation temperature, that is, when refrigerant vapor reaches the vicinity of the temperature sensor 10.

On the other hand, a liquid phase refrigerant outlet 17 is provided at the rear end of the water jacket 2, specifically at the rear end on the cylinder block 3 side, and at the front end of the water jacket 2, specifically at the front end on the cylinder head 4 side. A liquid phase refrigerant return port 18 is provided. The upper 32g X-phase refrigerant outlet 17 communicates with the upper part of the radiator 20 via the radiator inlet passage 19. This radiator 20 is also installed at the front of the vehicle, and 28 cooling fans are disposed at the front, which is likely the back. As the cooling fan 28, for example, a fan driven by engine output can be used. Note that the condenser 8 and the lanator 20 may be arranged one on top of the other, and the cooling fan 9 may be configured to forcibly cool both of them at the same time. The tip of the radiator outlet passage 21 connected to the lower outlet of the radiator 20 communicates with the liquid phase refrigerant return port 18 . On the upstream side of the liquid-phase refrigerant return port 18, a circulation pump 22, which serves as a refrigerant circulation means and a refrigerant supply means, is disposed, and is composed of an impeller pump or the like that is constantly driven by the engine output. Further, the radiator artificial passage 19 and the radiator outlet passage 21 are communicated with each other by a bypass passage 23, and a known thermostatic valve 24 is disposed in the bypass passage 23. The tip of the refrigerant supply passage 14 is connected to the upstream side of the thermostatic valve 24 of the radiator outlet passage 21 .

The heater core 25 is a heater core for heating the vehicle interior, and the tip of the heater inlet passage 26 connected to the refrigerant is connected to the rear end of the water jacket 2 on the cylinder head 4 side, and the refrigerant outlet is connected to the rear end of the water jacket 2 on the cylinder head 4 side. The tip of the heater outlet passage 27 connected to the circulation pump 22 is connected to the upstream side of the circulation pump 22 .

Next, FIGS. 2 and 3 show the water jacket 2
The figure shows a cross-section of the cylinder head 4 and the cylinder block 3 in a deaf state as viewed from one side, respectively.

As shown in FIG. 2.3, the liquid phase refrigerant return port 18 provided on the cylinder head 4 side of the water jacket 2 is
It communicates with the downstream side of the circulation pump 22 via a passage 31 formed at the bud end of the shilling block 3 . Continuing with this liquid phase refrigerant return port 18, a two-way gallery 32 is formed on the exhaust port 34 side of the cylinder head 4, and a supply port is provided to supply liquid phase refrigerant from there to each cylinder. 35 is formed. A portion of the water jacket 2 on the cylinder head 4 side communicates with a portion on the cylinder block 3 side via a plurality of communication holes 36. Further, liquid phase refrigerant is introduced from the cylinder head 4 side portion of the water jacket 2 into a manifold internal passage 37 provided at the lower part of the intake manifold (not shown), and the rear end of this manifold internal passage 37 A communication hole 38 is formed in the side portion of the cylinder block 3 to introduce the liquid phase refrigerant. On the other hand, if the liquid phase refrigerant is introduced into the cylinder head 1 side like this, the water jacket 2
In the cylinder block 3 side portion, a water gear rally 39 is formed on the intake boat 33 side, and is a groove for taking out the liquid phase refrigerant from the rear end to the radiator 20 and the heater core 25, respectively.

Now, in the boiling cooling device configured as above,
Basically, cooling is performed using the boiling and condensing cycle of the refrigerant. That is, the liquid phase refrigerant in the eater jacket 2 receives combustion heat and reaches approximately the saturation temperature, causing boiling and cooling various parts of the engine at that time. The refrigerant vapor generated here is led to the condenser 8 and condensed.
It is collected in the lower part and the reservoir tank 11. When the liquid phase refrigerant recovered in the reservoir tank 11 reaches a level set by the liquid level sensor 13 or higher, the first electromagnetic valve 15 is opened. Therefore, the reservoir tank 11 is connected to the upstream side of the circulation pump 22 via the refrigerant supply passage 14, and the liquid phase refrigerant is sent back from the reservoir tank 11 into the water jacket 2 by the action of the circulation pump 22, which is constantly driven by the engine output. It will be done. As a result, liquid phase refrigerant is always present in the water jacket 2 to an appropriate level.

On the other hand, the liquid phase refrigerant in the water jacket 2 is circulated between the radiator 20 in a liquid phase by the action of the circulation pump 22. That is, the liquid phase refrigerant taken out from the liquid phase refrigerant outlet 17 at the rear of the cylinder block 3 is guided to the radiator 20, where it radiates heat and becomes a slightly subcooled state, and then passes through the circulation pump 22 to the cylinder head. 4. Return the liquid phase refrigerant into the water jacket 2 from the front liquid phase refrigerant return port 18. This relatively low-temperature liquid phase refrigerant flows from the water gallery 32 toward the vicinity of the exhaust port 34 of each cylinder, flows through the communication hole 36.38 to the cylinder block 3 side, and then returns from the water gear gallery 39. The liquid phase refrigerant flows toward the outlet 17 .

Therefore, the liquid-phase refrigerant flow inside the water jacket 2 provides active forced convection to high heat load areas such as around the exhaust port 34 and between each cylinder, and the steam generated on these heat transfer surfaces Bubbles can be removed quickly. Therefore, even in a high heat flux region, a nucleate boiling state can be maintained within the relatively narrow restricted space of the water jacket 2, and an extremely excellent heat transfer coefficient can be ensured. In particular, since the liquid phase refrigerant that has become subcooled in the radiator 20 is supplied toward the high heat load area around the exhaust port 34, more reliable cooling is possible. Note that when the engine is not warmed up, that is, when the temperature is below the set temperature of the thermostat valve 24 (for example, about 90° C.), the thermostat valve 24 closes, thereby circulating the liquid phase refrigerant through the bypass passage 23. Since the introduction of refrigerant from the reservoir tank 11 side is stopped, warm-up characteristics are not impaired, and the cylinder wall temperature, etc. can be quickly raised. In addition, the heater core 25
The liquid phase refrigerant in the ETA jacket 2 is also circulated by the action of the circulation pump 22, and heating is performed using this high temperature liquid phase refrigerant as a heat source.

In the above embodiment, the liquid phase refrigerant condensed in the condenser 8 is sent back to the water jacket 2 using the circulation pump 22. However, in addition to the circulation pump 22, an electric pump is used as a refrigerant supply means. A refrigerant supply pump may be provided.

Effects of the Invention As is clear from the above explanation, according to the boiling/discharging cooling device for an internal combustion engine according to the present invention, the liquid phase refrigerant in a subcooled state is circulated through the liquid phase refrigerant in the water jacket that is in the boiling state. By introducing forced convection around high heat load areas, it is possible to reliably maintain a nucleate boiling state in high heat load areas such as around exhaust boats and between liners, which are generally comfortable restricted spaces. Effective cooling can be achieved using a high heat transfer coefficient. Therefore, local cooling failures can be prevented, for example in small high-power engines with small water jacket dimensions and high heat loads.
A high compression ratio is possible by suppressing knocking.

[Brief explanation of the drawing]

FIG. 1 is a structural explanatory diagram showing one embodiment of the present invention, FIG. 2 is a sectional view of a cylinder head portion thereof, and FIG. 3 is a sectional view of a cylinder block portion thereof. 1... Internal combustion engine, 2... Water jacket, 8.
... Capacitor, 13 ... Liquid level sensor, 15 ... First solenoid valve, 20 ... Radiator, 22 ... Circulation pump, 24 ... Thermostat valve.

Claims (1)

[Claims] (1) A water jacket in which liquid phase refrigerant is stored to an appropriate level and whose upper space is a vapor phase refrigerant area, a condenser that condenses the refrigerant vapor taken out from the upper part of this water jacket, and a liquid condensed in this condenser. A refrigerant supply means for supplying a phase refrigerant to the water jacket, a radiator for cooling the liquid phase refrigerant taken out from the water jacket, and a refrigerant circulation means for constantly circulating the liquid phase refrigerant between the radiator and the water jacket. A boiling cooling device for an internal combustion engine, characterized in that forced convection is applied to a high heat load section in a water jacket by means of a liquid phase refrigerant flow by the refrigerant circulation means.