JPS6036712A - Boiling and cooling apparatus for engine - Google Patents

Abstract

PURPOSE:To raise the thermal efficiency of a boiled and cooled engine, to raise the efficiency of its cooling system, to make the engine compact and light and to eliminate maintenance of the engine, by controlling a pump and a fan according to the operational conditions of the engine, and introducing liquid coolant into a cooling system from an external auxiliary tank when open air is introduced into the cooling system or when the engine is stopped. CONSTITUTION:Vapor of a coolant produced in a water jacket 22 of an engine 21 is cooled and liquefied in a condenser 23, to which forced draft of cooling air is supplied from a motor- driven fan 26, and the liquefied coolant is returned to the water jacket 22 by a motor-driven pump 25. The fan 26 and the pump 25 are controlled according to the temperature of coolant, the liquid level and the operational conditions of the engine to keep optimum cooling conditions. On the other hand, an auxiliary tank 50 disposed on the outside is connected to a by-pass passage of a lower tank 24 via a solenoid valve 53 for storing almost an equal amount of liquid coolant to the capacity of a gas-phase space 22a when the engine is operated. When operation of the engine 21 is stopped, a control circuit 30 opens a second auxiliary passage 52 by stopping current supply to a second solenoid valve 54 in response to the output signal of a temperature sensor 32. Further, if the coolant surface is not reached to the set level of a second liquid-level sensor 58 after starting of the engine, coolant is introduced into the cooling system by opening the solenoid valve 53, 55 and closing the solenoid valve 54.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Technical Field The present invention relates to a boiling cooling device that cools an engine using latent heat of boiling and vaporization of a coolant.

b. Technical background It is well known that in terms of thermal efficiency of an engine, it is desirable to increase the wall temperature of the combustion chamber as much as possible without affecting the durability and knock resistance of the material. Water-cooled engines had a simple configuration in which the cooling water was circulated between the engine's cooling water jacket and the radiator, and the cooling water circulation path was switched by a thermostand that opened and closed depending on the temperature of the cooling water. In general, the only effect that can be expected is to prevent engine overheating, and in other words, it is difficult and difficult to control the opening temperature optimally according to the operating conditions.

From this point of view, for example, as seen in Japanese Patent Application Laid-Open No. 58-5449, the temperature of the wall surface of the combustion chamber is detected and fed back to the cooling water pump drive unit, and the temperature is adjusted appropriately according to the operating state. A device has been proposed that continuously variable controls the cooling water circulation 1 so as to obtain the desired temperature, but this type of device basically cools the engine by returning the cooling water that has been radiated to the outside air in the radiator to the water jacket. Since it is still liquid phase circulation cooling, there is no choice between the conventional and common sense water cooling method from the standpoint of heat dissipation efficiency.In other words, the cooling water pump has a large drive loss because of the security of circulating a large amount of cooling water. Furthermore, problems remain, such as the difficulty in controlling the temperature in a responsive manner for automobile engines and the like whose operating conditions change rapidly.

In response to this, a boiling cooling device as seen in Japanese Patent Publication No. 57-57608, for example, has been proposed as a device that can secure the required heat dissipation bar with just 900 liters of cooling water using the latent heat of boiling vaporization of the cooling water. There is.

This is done by connecting the water jacket 2 of the engine 1 and the lower part of the radiator 3 through a passage 4, as shown in Figure 1, so that the level of the cooling water filled inside is the same in each. Cooling water vapor boiled and vaporized by the combustion heat is introduced into the radiator 3 through the upper space 5 of the jacket 2 and the steam passage 6, and the amount of condensed and liquefied steam cooled in the radiator 3 is introduced into the water jacket 2 through the passage 4.
A natural circulation cooling system is formed in which cooling water returns to the tank.

According to such a cooling device, heat is absorbed from the cylinder wall etc. by the latent heat of boiling and vaporization of the cooling water, so cooling is lower than that of general circulation cooling that relies on a heat capacity needle in the liquid phase of the cooling water. There are advantages such as less water consumption and even multi-cylinder engines can be cooled evenly since boiling starts from the high temperature parts of the engine.

However, on the other hand, according to the type of cooling system, the radiator 3 is filled with cooling water at the same level as the water jacket 2, and heat exchange occurs between the liquid phase cooling water and the outside air. The heat dissipation efficiency of the system does not necessarily improve, and since the pressure within the system is always kept constant, it has been difficult to variably control the cooling performance.

Furthermore, in this device, in order to stabilize the boiling point of the cooling water, that is, the amount of cooling heat, the pressure in the system is kept constant as described above, and for this purpose, only gas passes between the steam passage 6 and the atmosphere. Pressure is exchanged through a selectively permeable filter 7 that allows for this, but as a result of this, when the pressure in the system increases due to boiling and vaporization of the cooling water, some of the steam escapes to the outside. This makes it necessary to periodically replenish cooling water, and when the system pressure recovers as the temperature recovers after the engine stops, air is sucked in from the outside, causing problems such as subsequent deterioration of cooling performance. It is possible that

C0 Purpose of the Invention The present invention was devised against this technical background, and aims to improve thermal efficiency by controlling the optimum cooling state in response to changes in engine operating conditions, and also to improve the efficiency of the cooling system. The purpose of the present invention is to provide a boiling-cooled engine that meets the demand for a lighter, more compact engine and requires no maintenance.

d0 Disclosure of the Invention In order to achieve the above object, the present invention includes a condenser that cools and liquefies the refrigerant vapor generated in the water jacket of the engine, a lower tank that temporarily stores the refrigerant liquefied in the condenser, and a lower tank that recycles the liquid refrigerant in the lower tank. An electric pump that returns air to the water jacket and an electric fan that supplies forced cooling air to the condenser are installed, and the electric pump is controlled so that the liquid level of the refrigerant sealed in the water jacket reaches a predetermined value. In addition to increasing heat dissipation efficiency by exchanging heat between the refrigerant vapor and the outside air, the electric fan condenses the refrigerant in the condenser, thereby improving engine operation by changing the pressure within the system and the boiling point of the refrigerant. In order to control the temperature to the optimum temperature depending on the condition or operating range, we also installed an auxiliary tank that stores refrigerant externally, and if outside air enters the cooling system between the water jacket and condenser, it will be removed when the engine is stopped. By introducing liquid refrigerant from the auxiliary tank and filling the system with refrigerant, intruded air is discharged so that the cooling system can always perform as expected.

Embodiments of the present invention will be described below based on the drawings.

e. In the embodiment shown in FIG. 2 or 3, 21 is the engine (main body)
, 22 is the water jacket, 23 is the capacitor,
24 is a lower tank communicating with the lower part of the condenser 23;
5 is an electric pump, and 26 is an electric fan.

The water jacket 22 is attached to the cylinder block 21 so as to surround the cylinder of the engine 21 and the outer periphery of the furnace chamber.
a and the cylinder head 21b, and the potable refrigerant is sealed inside thereof to the extent that a suitable space (vapor phase space) 22a filled with refrigerant vapor remains. In a multi-cylinder engine, the gas phase space 22a communicates with each other between cylinders.

The water jacket 22 is connected to the condenser inlet portion 23a via a refrigerant injection pipe 22b and a vapor passage 27 connected to the water jacket 22 facing the gas phase space.

The refrigerant injection pipe 22b is located at the top of the path through which the refrigerant circulates, and the injection port 22C that rises above the ground is sealed with a camp 22d.

The lower tank 24 is connected to a refrigerant inlet portion 22e at the bottom of the water jacket 22 via a refrigerant passage 28 having an electric pump 25 interposed therebetween.

The condenser 23 is provided at a position through which running air flows when the vehicle is running, and the electric fan 26 is located on the front or back side of the condenser 23 to supply forced cooling air to the condenser 23.

30 & is a control circuit (FIG. 3) that controls the operation of the electric pump 25 and the electric fan 26, and is
The liquid level sensor 31 provided at 1b forms a control system together with a temperature sensor 32 and other detection means (not shown) for detecting the engine operating state.

The output of the liquid level sensor 31 changes on and off depending on whether the detection part is immersed in the refrigerant or exposed to the gas phase space 22a. Based on this change in output, the control circuit 30 determines whether the refrigerant liquid level is liquid or not. When the liquid level is corrected by a predetermined value depending on the position of the surface sensor 31, the electric pump 25 is driven to replenish the water jacket 22 with the refrigerant stored in the lower tank 24 until the liquid level reaches the predetermined level again. Therefore, a sufficient amount of refrigerant is always ensured within the water jacket 22. Note that the total volume 1 of the liquid phase refrigerant injected into the cooling system is such that the inside of the condenser 23 is almost in a gas phase state while the refrigerant is secured to the predetermined liquid level in the water jacket 22 as described above. It is set to a certain extent.

The temperature sensor 32 detects the engine temperature from the temperature or pressure of the refrigerant, and provides an output corresponding to the engine temperature as an actual temperature signal to the control circuit 30.
0 is the actual temperature detected value from this temperature sensor 32,
The operating state of the engine is determined by detecting engine rotation, throttle opening, fuel supply 1, etc. through well-known sensors, and the engine temperature is adjusted to an appropriate temperature according to the operating state based on comparison with the actual temperature. The electric fan 26 is controlled to operate or stop in this manner.

It goes without saying that the relationship between the engine operating state and the control@dark value can be set freely depending on the engine specifications, purpose, and application, but generally speaking, automobile engines are used in urban driving areas where the load and engine speed are relatively low. and other high-speed or high-load areas. In urban driving areas, the temperature is lowered to increase thermal efficiency, and in high-speed/high-load areas, the temperature is lowered to prevent abnormal combustion.

To explain the basic operation of the cooling system based on the above, when the liquid phase refrigerant in the water jacket 22 is heated by the engine combustion heat, it reaches a boiling point depending on the pressure in the system at that time. At that point, it begins to boil, taking away the latent heat of vaporization and evaporating. At this time, the refrigerant actively boils at the high temperature part t1 of the engine 21 and cools down the amount equivalent to the latent heat of vaporization, so the combustion chamber and cylinder wall are kept at a nearly uniform temperature. This makes it possible to raise the overall temperature of the combustion chamber, etc., since hot spots that promote combustion are less likely to occur.

The refrigerant vapor generated as a result of the boiling cooling action is transferred to the steam passage 2.
The liquid enters the condenser 23 through the capacitor 7, is cooled and liquefied by heat exchange with the outside air, and is sequentially stored in the lower tank 24. In this case, as described above, the inside of the condenser 23 is maintained in a gas phase, and the high-temperature refrigerant vapor is cooled by the outside air under good heat transfer conditions with the metal surfaces that constitute the condenser 23. Therefore, the heat dissipation efficiency is significantly improved compared to the case where heat is dissipated in the liquid phase, and therefore, the capacitor 23 and the electric fan can be significantly smaller than those in the past.

Then, the refrigerant that has been liquefied in the condenser 23 and stored in the lower tank 24 is returned to the water jacket 22 again by the operation of the electric pump 25 as the liquid level in the water jacket 22 decreases, and by repeating the above process, the refrigerant is boiled. Cooling continues.

By the way, when the Ganrin engine with a total of 1t180occ is running at full throttle at 4000rl)m, the cost and heat radiation is more than 400kCa1 per minute.
The required circulation 1Q of cooling water to accomplish this through liquid phase circulation cooling of the cooling water is 00Q, assuming that the radiator inlet temperature is 88℃, the radiator outlet temperature is 84℃, and the specific heat of water is 1. ' c s s m 5-1-)-x-1+
110 h,'''! ri reaches about 1101 per minute.

On the other hand, in boiling cooling, when water is used as a refrigerant, its latent heat of vaporization is approximately 539 kcal/Kg, so the required circulation rate of liquid phase refrigerant is only several hundred CC per minute. As a result, the electric pump 25 can be small and driven with a small current, making it easy to control, and in particular, driving loss is significantly reduced compared to an engine-driven water pump for water circulation cooling, even at the same temperature. This results in a significant improvement in fuel efficiency.

Next, we will explain the operation of the cooling system associated with temperature control.
First, an example of the operational concept of the control system will be explained.

As mentioned earlier, the control system operates so that the engine temperature ultimately reaches the target value depending on the operating condition at that time, by controlling the operation of the electric engine 26. For this purpose, first, the operating state is determined from the relationship between the engine rotation speed and load, and in urban driving areas where the rotation speed and load are relatively low, control 1@degree target value T is set. The high temperature side target value TH (for example, equivalent to TH - 1io℃) set in advance is selected as T, and the low temperature side target value TL (for example, Tt - g□
(equivalent to ℃).

Next, the final target value T mentioned above. and actual engine temperature Ta
When Ta≧TO, the electric fan 26 is driven to supply cooling air to the condenser 23 to actively cool it. On the contrary, when Ta (To), the electric fan 26 is stopped and the condenser 23 is left in a natural cooling state.

The control system repeatedly executes such operations periodically or continuously to control the engine temperature, so fj)! D, and the cooling system operates as follows.

That is, in the present invention, since the inside of the capacitor 23 is maintained in the gas phase to improve heat dissipation efficiency, the electric fan 26
When the forced cooling air is supplied, the refrigerant vapor in the condenser 23 is quickly liquefied by the forced cooling air, which lowers the pressure in the system and lowers the boiling point of the liquid refrigerant. will also decline accordingly. On the other hand, when the electric fan 26 stops, the condenser 2
The amount of heat dissipated in the water jacket 22 decreases, causing the refrigerant to liquefy inside the water jacket 22, but the force of boiling and vaporizing it in the water jacket 22 is greater than that, increasing the pressure in the system and raising the engine temperature. It's getting worse.

In this way, the engine 21 changes its temperature in a responsive manner such that it is high in low speed/low load ranges and low in high speed/high load ranges. Not only can abnormal combustion such as non-king and detonation be avoided by suppressing the engine temperature at high speeds and high loads, but also by keeping the engine at an appropriate high temperature during regular city driving, it reduces cooling loss and improves fuel consumption. It goes without saying that effects such as being enhanced can be obtained. In addition, especially in diesel engines, by keeping the combustion chamber at a high temperature during full speed rotation such as during idle link, the ignition delay period of the injected fuel is reduced. In other words, the ratio of premixed combustion is reduced, so the rise in cylinder internal pressure is reduced. As the pressure becomes more gradual, noise and vibration are reduced, and the average effective pressure is increased, leading to further improvements in fuel efficiency.

The present invention is characterized in that a liquid refrigerant is introduced from the outside when the engine is stopped for the direct purpose of eliminating air that has entered the system in such a boiling cooling system. , This point will be explained next.

In FIG. 2 or 3, reference numeral 50 denotes an auxiliary tank for storing a liquid refrigerant equal to the volume of the gas phase space 22a generated between the water jacket 22 and the liquid level of the lower tank 24 during engine operation, and 51 is an auxiliary tank. 50 is a first auxiliary passage that communicates with the refrigerant passage 28 of the cooling system, 52 is a second sleeve auxiliary passage that communicates the auxiliary tank 50 with the engine water jacket 22, and 53 is a passage that connects the suction side of the electric bonder 25 with the lower tank 24 side. The passage 28 is a first solenoid valve (three-way valve) that selectively communicates with the first auxiliary passage 51, 54 is a second solenoid valve that opens and closes the second auxiliary passage 52, and 55 is near the top of the gas phase space 22B. This is a third solenoid valve that opens or closes the air to the atmosphere.

The inside of the auxiliary tank 50 is maintained at atmospheric pressure via a filter cap 50a having a ventilation function, and the third solenoid valve 55 corresponds to the top of the internal upper blade space and the gas phase space 22a of this auxiliary tank 50. It is interposed in the middle of the air passage 56 that communicates with the refrigerant injection port 22C.

Furthermore, when the first electromagnetic tank 53 is not energized, it communicates between the p-tank 24 and the electric pump 25, but when it is energized, it connects the auxiliary tank 50 to the electric pump 2 through the first auxiliary passage 51.
Connect to the suction side of 5. On the other hand, the second solenoid valve 54
is the valve held open when not energized and opened when energized, and the third solenoid valve 5
5 is set so that the valve is not held closed when not energized, and is open when energized.

Note that 57 is a manual cock interposed in the middle of the second auxiliary passage 52 so as to be located between the second solenoid valve 54 and the auxiliary tank 50, and after the engine is assembled, the cock 57 is closed. The camp 22d is removed, and liquid refrigerant is injected until the mouth of the injection port 22C is almost full. After injecting the refrigerant, the camp 22d is tightened and the manual cock 57 is left open.

The control system that controls the opening, closing, or switching of each of the electromagnetic valves 53 to 55 includes, in addition to the FC liquid level sensor 31 and temperature sensor 32 described above, a second liquid level sensor 58 that detects the refrigerant liquid level position in the lower tank 24. and a third liquid level sensor 59 for detecting the refrigerant 1 at the injection port 22C when the engine is stopped, and the control circuit performs the following control operations based on signals from each of the sensors.

In other words, when the engine is cold, the cooling system is filled with liquid refrigerant as described above, but when the engine 21 is started from this state, the refrigerant in the water jacket 22 is heated by combustion heat and gradually cools down. It begins to vaporize. During this time, the control circuit 30 cuts off the power to each of the solenoid valves 53 to 55, that is, the first N solenoid valve 53 is connected to the lower tank 2.
4 and the electric pump 25, the second solenoid valve 54 is opened,
The third magnetic valve 55 is closed. Therefore, as the refrigerant vaporizes, the pressure within the system increases, and accordingly, the liquid refrigerant in the water jacket 22 is pushed out to the auxiliary tank 50 via the second auxiliary passage 52.

In this way, when the engine 21 is started, the refrigerant liquid level in the water jacket 22 gradually decreases, but when the liquid level falls below the position detected by the first liquid level sensor 31, the electric Since the pump 25 operates to replenish the refrigerant from the lower tank 24, the refrigerant liquid level in the water jacket 22 does not drop any further.
Apparently, the refrigerant on the condenser 23 side is pushed out to the auxiliary tank 5o, lowering its liquid level.

Then, when the liquid level in the capacitor 23 drops further by one level to the point where the second liquid level sensor 58 is facing the space, the control circuit 30 detects this and controls the second electromagnetic valve 54. Turn on the power and close it 6. As a result, the cooling system will be filled with the standard sound refrigerant as shown in Figure 2, and from then on it will perform the cooling function according to the temperature control operation described above. become.

In addition, at the time of startup, the inside of the capacitor 23 is in the inebriated phase as the cold tjL liquid level in the system decreases as described above, so the heat radiation 1 is
(Fig. 2).

Therefore, the heat generated by the Ensif 210 does not wastefully escape to the outside, and therefore, warming up is completed in a short time.

Next, when the engine 21 is stopped from the state shown in FIG. Normal operation to the solenoid valve 54 is stopped and the second auxiliary passage 52 is opened.

At this time, the refrigerant vapor in the system condenses and liquefies as the temperature decreases after the engine stops, and the internal pressure is reduced, so when the second auxiliary passage 52 opens, the refrigerant stored in the auxiliary tank 50 flows into the water jacket. 22, and eventually the third liquid level sensor 59 unless outside air enters the system.
At level 1, it will be filled with liquid refrigerant.

On the other hand, if a certain amount of outside air has entered the system, negative pressure in the system will be hindered by that amount, so the refrigerant should be introduced from the auxiliary tank 50 until its liquid level The process ends before the liquid level sensor 59 is reached.

In such a case, the control circuit 30 uses, for example, the temperature sensor 32.
After determining that the engine 21 has settled down to room temperature based on the fact that the signal from detects that the liquid has not reached the specified value, and energizes the first solenoid valve 53 to switch and connect the first auxiliary passage 51 to the suction side of the electric pump 25, and also drives the electric pump 25 to reduce the liquid level in the auxiliary tank 50. The refrigerant is pumped to the water jacket 22. Also,
At this time, the second and second solenoid valves 54 and 55 are also energized to close the second auxiliary passage 52 and close the water jacket 22.
While preventing the refrigerant from flowing back into the auxiliary tank 50, the injection port 22c at the top of the gas phase space is opened to the space of the auxiliary tank 50, that is, to the atmosphere. This unity,
As the liquid level in the system gradually rises, the intruding air is exhausted to the outside (auxiliary tank 5 (1). This air bleeding control is continued until the liquid level in the system reaches the specified value, that is, the third When the level detected by the liquid level sensor 59 is reached, each electromagnetic valve 53 to 55 and the electric pump 2
The process ends by cutting off the power to 5.

In this way, if harmful air has entered the cooling system, there will be no automatic action to remove it after the engine is stopped or immediately after starting, and the performance of the cooling system will therefore be maintained. It is guaranteed for a long time without having to worry about management work.

As explained in detail about the f1 invention, according to the present invention, the interior of the condenser that liquefies refrigerant vapor is basically maintained in a gas phase state to improve heat dissipation efficiency, and the cooling to this highly efficient condenser is improved. The boiling point of the refrigerant liquid is controlled by changing the wind power through an electric fan, making it possible to significantly reduce the weight and size of the engine system.
The temperature can be quickly controlled to an appropriate temperature depending on the operating condition, and therefore fuel efficiency can be effectively increased.

Furthermore, the present invention prevents outside air from entering the system by introducing liquid refrigerant from an external auxiliary tank to fill the cooling system with refrigerant when the engine is stopped, and also prevents outside air from entering the system. By eliminating this, the reliability and stability of the cooling device are further improved.
In addition, it has the effect of making maintenance easier.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional example. FIG. 2 is a schematic configuration diagram of an embodiment of the present invention, and FIG. 3 is a schematic configuration diagram also including the configuration of a control system and showing different operating states of the calyx. 21... Engine (main body), 22... Water jacket, 22a... Gas phase space, 22b... Refrigerant injection pipe, 23... Condenser, 24... Lower tank, 2
5...Electric pump, 26...Electric fan, 28...
・Refrigerant passage, 30... control circuit, 31.58.59.
...Liquid level sensor, 32... Temperature sensor, 50... Auxiliary tank, 51... First auxiliary passage, 52... Second auxiliary passage, 53... First solenoid valve, 54...・Second solenoid valve, 55...31st! Magnetic valve. Special pestle applicant Nissan Motor Co., Ltd. 125 = Figure 1 To Figure 2 5 Figure 3

Claims (1)

[Claims] A condenser that cools and liquefies refrigerant vapor from the engine water jacket, a lower tank that temporarily stores the liquefied refrigerant from the condenser, an electric pump that returns the liquefied refrigerant from the lower tank to the water jacket, and an electric fan that supplies forced cooling air to the condenser. A circuit detects the engine temperature and drives an electric fan at a predetermined high temperature, and a circuit detects the refrigerant liquid level in the water jacket and drives an electric pump until the liquid level reaches a predetermined level when the liquid level is discharged. A boiling cooling system for an engine, in which the liquid refrigerant is sealed to such an extent that the internal upper blade of the water jacket and substantially the entire interior of the condenser become a gas phase space under conditions where the liquid refrigerant satisfies a predetermined liquid level. , an auxiliary tank for storing a liquid refrigerant having at least the same level of sound as the gas phase space, a first auxiliary passage for introducing α-type refrigerant from the auxiliary tank into a refrigerant passage between the electric pump and the lower tank, and an electric pump. Connect the suction side to the refrigerant passage on the lower tank side or the
a first solenoid valve that selectively communicates with any of the auxiliary passages, a second auxiliary passage that introduces liquid refrigerant from the auxiliary tank into the water jacket, and a second solenoid valve that opens and closes the second auxiliary passage;
A third solenoid valve is provided to open or close the vicinity of the top of the gas phase space to the atmosphere, and a control system is formed to switch and control each of the solenoid valves according to the engine condition and the amount of liquid refrigerant in the cooling system. Boiling cooling system for engines.