JPH0214966B2 - - Google Patents

Description

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

b. Technical Background It is well known that it is preferable in terms of thermal efficiency to increase the wall temperature of the engine combustion chamber, etc., as high as possible within a range that does not impede the durability and knock resistance of the material, but conventional water-cooled cooling systems Since it has a simple configuration in which coolant is circulated between the engine's water jacket and the radiator, and the coolant circulation path is switched using a thermostatic valve that opens and closes depending on the coolant temperature, it is essentially In other words, it has been difficult to control the engine temperature to the optimum level according to the operating conditions with the aim of improving efficiency. Another drawback was that it took a long time to warm up.

On the other hand, as a cooling device that uses the latent heat of boiling vaporization of the cooling water to secure the required amount of heat radiation with a small amount of cooling water and obtain appropriate cooling performance, for example, Figs. The ones shown in are known.

Figure 1 shows the cooling system disclosed in Japanese Patent Publication No. 57-57608.
The lower part of the radiator 3 is communicated with the lower part of the radiator 3 through a passage 4 so that the liquid level of the cooling water filled inside is the same in each case, and the cooling water vapor boiled and vaporized by the combustion heat is transferred to the upper space 5 of the jacket 2. A natural circulation cooling system is formed in which cooling water is introduced into the radiator 3 via the steam passage 6 and returned to the water jacket 2 via the passage 4 in proportion to the amount of condensed and liquefied steam cooled by the radiator 3. are doing.

Cooling using the boiling latent heat of vaporization of the coolant requires less cooling water capacity than general circulation cooling, which relies on the heat capacity of the coolant in its liquid phase, and also prevents boiling from the high-temperature parts of the engine. This provides advantages such as uniform cooling.

However, according to this cooling system, the radiator 3 is filled with cooling water at the same level as the water jacket 2, and heat is exchanged between the liquid phase cooling water and the outside air, which have a small mutual temperature difference. The heat dissipation efficiency of the cooling system does not necessarily improve, and therefore it is inconvenient to quickly variably control the cooling performance depending on the operating state. Furthermore, this device uses a selectively permeable filter 7 that only allows gas to pass between the steam passage 6 and the atmosphere in order to keep the pressure in the system constant and stabilize the boiling point of the cooling water and the engine temperature. However, as a result of this, when the pressure inside the system increases due to boiling and vaporization of the cooling water, some of the steam escapes to the outside, so it is necessary to periodically replace the cooling water. This necessitates replenishment, and when the pressure in the system drops as the temperature drops after the engine is stopped, air is sucked in from the outside, which poses problems such as the possibility that the cooling performance will deteriorate thereafter.

Figure 2 shows the cooling system of U.S. Pat. No. 4,367,699, in which a separator 8 holds cooling water at the same level as the water jacket 2 of the engine 1.
Cooling water vapor from the engine 1 is introduced into the space through the steam passage 6a, and only this steam is passed through the passage 6.
After being supplied to the radiator 3 (condenser) via the radiator 3 (condenser) and liquefied for cooling, it is returned to the separator 8 by the pump 9 and passage 4a, and then returned to the engine 1 by gravity via the passage 4b.

According to this device, only high-temperature cooling water vapor is introduced into the radiator 3 and is liquefied into cooling water vapor, which improves heat dissipation efficiency. Since pressure fluctuations within the system are suppressed by communicating the system with the atmosphere through the air vent 11, problems regarding maintenance and cooling performance similar to those shown in FIG. 1 arise. Furthermore, since vapor and liquid phase refrigerant are supplied through the separator 8, the structure becomes complicated and restrictions on the layout increase.

Furthermore, FIG. 3 shows a cooling system proposed in Japanese Patent Application Laid-Open No. 56-32026, which, unlike the previous two examples, maintains the inside of the water jacket 2 of the engine 1 in a gas phase at all times, and cools the cylinder 13 through the nozzle 12. Surface layer 1
The engine is cooled by a cycle in which cooling water is injected into the nozzle 4 and evaporated, the vapor is cooled and liquefied in the radiator 3, and then supplied to the nozzle 12 again via the pump 9.

However, in this device, the surface layer 14 is formed of a porous material so that the coolant sprayed and supplied evenly spreads over the surface of the cylinder 13.
When boiling and vaporization becomes active in the surface layer 14, permeation of cooling water from the surface is blocked, temporarily making it impossible to dissipate heat, and as a result, there is a risk that problems such as overheating and seizure may occur.

c. Purpose of the Invention The present invention was made against the above technical background, and aims to improve thermal efficiency by controlling an engine to an optimal cooling state that responds quickly to changes in operating conditions, and also to improve the efficiency of the cooling system. The purpose of the present invention is to provide a boiling cooling device that meets the demands for increased weight and miniaturization, and also requires no maintenance.

d. Disclosure of the Invention () To achieve the above object, the present invention (first invention) provides a condenser that cools and liquefies refrigerant vapor generated in the water jacket of an engine, which is mostly filled with liquid-phase refrigerant; A cooling system consisting of a tank that temporarily stores the refrigerant liquefied in the condenser, a supply pump that returns the liquefied refrigerant from the tank to the water jacket, and a cooling fan that supplies forced cooling air to the condenser is installed and enclosed in the water jacket. The supply pump is controlled so that the liquid level of the cooled refrigerant reaches a predetermined value, and the condenser exchanges heat between the refrigerant vapor and the outside air, which has a large temperature difference, increasing heat dissipation efficiency and reducing the engine temperature. The optimum temperature (predetermined value) according to the engine operating condition or operating range is achieved by changing the amount of refrigerant condensed in the condenser, that is, the pressure in the system and the boiling point of the refrigerant, through a cooling fan activated by this detection signal. In addition to making the system controllable, the refrigerant passage is made into a closed loop during normal operation after warming up.

Next, embodiments of the above invention will be described based on the drawings.

e Example In Fig. 4, 21 is the engine (main body), 2
2 is a water jacket, 23 is a condenser, 24 is a tank (lower tank) communicating with the lower part of the condenser 23, 25 is an electric pump as a supply pump, and 26 is an electric fan as a cooling fan.

The water jacket 22 is formed over the cylinder block 21a and the cylinder head 21b so as to surround the outer periphery of the cylinder and combustion chamber of the engine 21, and is designed to the extent that an appropriate space (gas phase space) 22a remains inside thereof. A liquid phase refrigerant is enclosed. In a multi-cylinder engine, the gas phase space 22a communicates with each other between cylinders.

The water jacket 22 communicates with the condenser inlet portion 23a via a refrigerant injection pipe 22b and a vapor passage (refrigerant passage) 27 connected 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 upwardly rising injection port 22c is sealed with a cap 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 the electric pump 25 and the electric fan 2
6, and forms a control system together with a liquid level sensor 31 provided in the cylinder head 21b, a temperature sensor 32, and other detection means (not shown) for detecting the engine operating state. There is.

The output of the liquid level sensor 31 changes on and off depending on whether the detection part is immersed in the refrigerant liquid or exposed to the gas phase space 22a, and the control circuit 30 determines whether the refrigerant liquid level is high based on this change in output. When the liquid level falls below a predetermined value depending on the position of the liquid level 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 predetermined amount of refrigerant is always ensured within the water jacket 22. Note that the total capacity of the liquid phase refrigerant injected into the cooling system is such that the inside of the condenser 23 is almost in the 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 the extent that

On the other hand, the temperature sensor 32 detects the engine temperature from the refrigerant temperature and provides an output corresponding to the engine temperature to the control circuit 30 as an actual temperature signal.
The control circuit 30 detects the actual temperature detected by the temperature sensor 32 as well as engine rotation, throttle opening, fuel supply amount, etc. through well-known sensors, determines the operating state of the engine, and determines the actual temperature. Based on the comparison, the operation or stop of the electric fan 26 is controlled so that the engine temperature is appropriate depending on the operating state.

It goes without saying that the relationship between the engine operating state and the control temperature 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, the temperature is raised in urban driving areas to improve thermal efficiency, and the temperature is lowered in high-speed/high-load areas to prevent abnormal combustion.

To explain the basic function 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 according to the pressure in the system at that time. At that point, it starts boiling, takes away the latent heat of vaporization, and evaporates. At this time, the refrigerant boils more actively in the higher temperature parts of the engine 21 and cools the combustion chamber and the cylinder wall by the amount equivalent to the latent heat of vaporization. Since hot spots are less likely to occur, it is possible to raise the overall temperature of the combustion chamber, etc.

The refrigerant vapor generated as a result of the boiling cooling action enters the condenser 23 through the vapor passage 27,
It is cooled and liquefied by heat exchange with the outside air, and is sequentially stored in the lower tank 24. In this case, as mentioned above, the inside of the capacitor 23 is maintained in a gaseous state,
Since the high-temperature refrigerant vapor is cooled by the outside air under good heat transfer conditions with the metal surface that constitutes the condenser 23, the heat radiation effect is greatly enhanced compared to the case where heat is radiated in the liquid phase. capacitor 2
3 and electric fans that are significantly smaller than conventional ones can be used. Incidentally, Figure 5 shows the relationship between the fan air speed required to maintain the engine temperature at 100°C and the engine rotation speed when the engine is operated at full load. Efficiency is increasing.

Then, it is liquefied in the condenser 23 and lower tank 2
The refrigerant stored in the water jacket 22
As the liquid level decreases, the electric pump 25 operates to return the liquid to the water jacket 22, and the boiling cooling continues by repeating the above process.

By the way, when a gasoline engine with a total displacement of 1,800 c.c. is operated at full throttle at 4,000 rpm, the required discharge amount is over 400 kcal per minute, as shown in Figure 6, and this is caused by the liquid phase of the cooling water. The required circulation amount Q of cooling water for complete circulation cooling is Q = 400/(88-84) x 1, assuming that the radiator inlet temperature is 88℃, the radiator outlet temperature is 84℃, and the specific heat of water is 1. It reaches ≒100Kg, or about 100 kg per minute. On the other hand, boiling cooling
When water is used as a refrigerant, its latent heat of vaporization is approximately
Since it is 539 kcal/Kg, the required circulation amount of liquid phase refrigerant is only a few 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. As shown, fuel efficiency is significantly improved even at the same temperature (80°C).

Next, in explaining the operation of the cooling system associated with temperature control, an example of the operational concept of the control system will first be explained.

As mentioned earlier, the control system is based on the electric fan 26.
By controlling the operation of the engine, the engine temperature ultimately reaches the target value according to the operating condition at that time.To do this, the operating condition must first be determined from the relationship between the engine speed and the load. In urban driving areas where the rotational speed and load are relatively low, a preset high-temperature target value T _H (e.g., T _H = 110°C) is selected as the control temperature target value T _p , and in other high-speed Or the same in high load range
Select a low temperature target value T _L (for example, equivalent to T _L = 90°C) as T _p .

Next, the final target value T _p and the actual engine temperature T _a are compared, and when T _a T _p is reached, the electric fan 26 is driven to supply cooling air to the condenser 23, and this is actively Cool to On the contrary, T _a
<T _p , 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, and in response, the cooling system operates as follows.

That is, in the present invention, since the inside of the condenser 23 is kept in the gas phase to improve heat dissipation efficiency, when forced cooling air is supplied by the electric fan 26, the refrigerant vapor in the condenser 23 is quickly reacted to the forced cooling air. Liquefaction is promoted, and as a result, the pressure within the system decreases, the boiling point of the liquid refrigerant also decreases, and the engine temperature accordingly decreases accordingly. On the other hand, electric fan 2
6 stops, the amount of heat dissipated by the condenser 23 decreases, and the amount of heat dissipated from the water jacket 22 is greater than the amount of liquefied refrigerant inside the condenser 23, especially when the vehicle speed is low and there is insufficient airflow, such as when driving in a city. Since the amount of boiling vaporization exceeds the amount of boiling and vaporizing, the pressure in the system increases and the engine temperature increases.

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 knocking and detonation be avoided by suppressing the engine temperature at high speeds and high load ranges, but also by keeping the engine at an appropriate high temperature in commonly used city driving ranges, cooling loss is reduced and fuel consumption is reduced. Needless to say, effects such as improved performance (see Fig. 7) can be obtained. Particularly in diesel engines, by keeping the combustion chamber at a high temperature during low-speed rotation such as when idling, the ignition delay period of the injected fuel is reduced, or in other words, the proportion of premixed combustion is reduced, as shown in Figure 8. As a result, the cylinder pressure rises more slowly, reducing noise and vibration, and increasing the average effective pressure, leading to further improvement in fuel efficiency.

FIG. 9 shows a specific circuit example of a control system that executes the temperature control operation described above.

This circuit is adapted to a gasoline engine equipped with an electronically controlled fuel injection device, and detects the engine operating state from the drive signal pulse of the electromagnetic fuel injection valve 40 provided facing the engine intake passage (not shown). .

In an electronically controlled fuel injection system, fuel is pressurized and supplied to the fuel injection valve 40 so that the relative pressure between it and the engine suction negative pressure is always constant, and the valve opening time of the injection valve 40, that is, the injection valve drive signal The amount of fuel injection is controlled by changing the pulse width of.

Therefore, a drive signal to the injection valve 40 is applied to the base of the transistor Tr, and only while this base voltage is applied (while the injection valve 40 is open), a clock signal is applied to the ripple counter 41 having a predetermined characteristic. If the output of the counter 42 is given, as shown in FIG.
The ball starts to come out. In this case, the injection valve drive signal is input to the reset terminal of the counter 41, and the pulse width is detected every time the injection timing arrives.

Further, the injection valve drive pulse is issued in synchronization with the engine rotation, and therefore, as the engine rotation speed increases, the number of the above-mentioned carries per unit time increases.

In short, the length or number of carries output from the counter 41 within a certain period of time increases as the fuel injection amount (that is, load) or rotational speed increases, so this is input to the smoothing circuit 43 and smoothed. As shown in FIG. 9B, an output voltage proportional to the load or rotational speed can be obtained.

The output voltage of this smoothing circuit 43 is input to a first comparator 44 and compared with the voltage at point P obtained by dividing the output of the constant voltage power supply 45 by resistors R ₁ and R ₂ . P
The potential appearing at the point corresponds to a reference value for determining the engine operating range.

The first comparator 44 outputs an output when the output voltage of the smoothing circuit 43 becomes higher than the potential at point P, that is, when the engine reaches a certain high speed or high load range (FIG. 9B). This output voltage is connected to resistor _R3
The voltage is divided by R ₄ (point Q), and the second comparator 46
The potential set by the resistors R ₃ and R ₄ here corresponds to the low temperature target value (T _L ).

The second comparator 46 compares the potential at the point R, which is obtained by dividing the output from the constant voltage power supply by the resistor _R6 and the thermistor 47 serving as the temperature sensor 32, with the potential at the point Q, and the potential at the point Q is determined by the potential at the point R. When the temperature rises higher than , the relay switch 48 is driven to energize the electric fan 26. Since the thermistor 47 has a characteristic that its resistance value decreases as the temperature rises, as the engine temperature rises, the potential at point R falls. Therefore, when the engine temperature rises above the temperature target value (T _Q ) represented by the potential at point Q in the high-speed/high-load range, the electric fan 26 operates and starts active cooling (Fig. 9C reference).

On the other hand, at point Q, the potential obtained by dividing the output of the constant voltage power supply 45 by the resistors R ₅ and R ₄ always appears, regardless of the operating state of the engine. In a low load range, the electric fan 26 operates when the potential at point R is lower than the potential at point Q, which is determined by resistors _R5 and _R4 . Since the Q point potential at this time is set lower than that at high speed and high load in order to correspond to the high temperature side temperature target value (T _H ), the electric fan 24 operates at a lower temperature than at high speed and high load. (Figure 9C).

In this way, the control system achieves the desired control objective of keeping the engine temperature low in high speed and high load ranges and high in city driving ranges.

f Disclosure of the invention () Next, the second invention will be explained.

The present invention achieves the same object as the first invention, and further controls the increase/decrease of the amount of refrigerant in the cooling system to perform advanced engine temperature control corresponding to various operating conditions, and to control the air This prevents contamination and efficiently discharges it, thereby further increasing the reliability and maintainability of the cooling device.

That is, in the present invention, in addition to the configuration of the first invention, an auxiliary tank storing a liquid phase refrigerant having at least the same capacity as the gas phase space is disposed so as to be communicated with the refrigerant passage, so that the cooling system is After the engine has stopped, the negative pressure in the system supplies liquid phase refrigerant from the auxiliary tank to the refrigerant passage, reducing the heat dissipation efficiency of the condenser and preventing overcooling, as well as preventing air from entering due to the negative pressure, and starting the engine. When it is detected that there is no liquid refrigerant near the top of the refrigerant passage immediately after the cold, liquid refrigerant is supplied from the auxiliary tank into the refrigerant passage to replace the mixed air with liquid, and the air in the refrigerant passage is replaced with liquid. During engine warm-up, the liquid phase refrigerant in the refrigerant passage returns to the auxiliary tank until the refrigerant liquid level in the refrigerant passage reaches a predetermined value. During normal operation thereafter, communication between the tank and the supply pump was maintained, and temperature control was performed with the refrigerant passage closed as a loop. Therefore, the function of the cooling device at this time is the same as in the first invention.

The present invention will be explained below based on illustrated embodiments.

g Example In FIGS. 10 to 13, 50 is an auxiliary tank, 51 is a first auxiliary passage, 52 is a second auxiliary passage,
53 is a first solenoid valve (three-way valve), 54 is a second solenoid valve,
55 is a third solenoid valve.

The inside of the auxiliary tank 50 communicates with the atmosphere through a filler cap 50a that has a ventilation function, and is installed at a high position, so the liquid phase refrigerant stored inside flows into the refrigerant system based on gravity. It will be introduced.

In this case, the first solenoid valve 53 communicates between the lower tank 24 and the electric pump 25 when it is not energized, but when it is energized, it communicates between the auxiliary tank 50 and the suction side of the electric pump 25 via the first auxiliary passage 51. do. Further, the second solenoid valve 54 is normally open and closed when energized, and the third solenoid valve 55 is normally closed and opened when energized. Note that the third solenoid valve 55 is interposed in the middle of an air passage 56 that communicates the refrigerant inlet part 22c with the internal upper space of the auxiliary tank 50, and when the third solenoid valve 55 is opened, the inlet part 22c is closed. Filler cap 5 having a ventilation function for the auxiliary tank 50
Open to atmosphere via 0a.

In addition to the liquid level sensor 31 and temperature sensor 32 described above, the control system that controls the opening, closing, or switching of each of the electromagnetic valves 53 to 55 includes a second liquid level sensor 57 that detects the refrigerant liquid level position in the lower tank 24. , a third liquid level sensor 58 that detects the amount of refrigerant after the engine is stopped at the injection port 22c at the top of the gas phase space 22a, and a control that executes a predetermined control operation based on the signals from each of the sensors. A circuit 30' etc. are provided.

Since the other points are the same as those in FIG. 4, the same parts are given the same reference numerals and the explanation thereof will be omitted.

Next, the effect based on the above configuration will be explained together with the operation of the control system.

FIG. 10 shows the state of the cooling system under normal operating conditions, in which liquid phase refrigerant is supplied to the water jacket 22 via an electric pump 25 so as to maintain a predetermined level determined by a liquid level sensor 31. At the same time, an appropriate amount of liquid phase refrigerant remains in the lower tank 24 and the inside of the condenser 23 is maintained in the gas phase, that is, a standard amount of refrigerant is held in the system.

At this time, the control circuit 30' energizes the second solenoid valve 54, while cutting off the energization to the first and third solenoid valves 53, 55, so that the lower tank 24 and the electric pump 25
while maintaining the communication state of the first auxiliary passage 51.
In addition, the second auxiliary passage 52 is closed. Therefore, the function of the cooling device in this state is exactly the same as that shown in FIG. 4, and the engine temperature is controlled to a predetermined value depending on the operating state at that time. Ru.

Next, when the engine 21 is stopped from this state, the control circuit 30' controls the second solenoid valve as shown in FIG. 54 is stopped and opened, and the auxiliary tank 50 and the refrigerant passage 28 of the cooling system are communicated via the second auxiliary passage 52.

At this time, the refrigerant vapor in the system liquefies as the temperature decreases after the engine stops, and the internal pressure becomes negative, so the refrigerant stored in the auxiliary tank 50 is introduced into the system through the second auxiliary passage 52. As a result, as shown in the figure, the system is gradually filled with liquid refrigerant, preventing air from entering. Finally, the gas phase space 22
It will be filled with liquid phase refrigerant up to the level of the liquid level sensor 58 located at the top of point a.

On the other hand, if outside air enters 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 is at the third liquid level. The process ends before reaching the sensor 58.

In this case, the control circuit 30' determines that the engine 21 has settled down to room temperature because the signal value from the temperature sensor 32 has stopped changing, or immediately after a cold start, the control circuit 30' detects the third liquid level sensor 5.
8, it is detected that the liquid level in the system has not reached the specified value, that is, the liquid level when outside air has not entered, and the first
The electromagnetic valve 53 is energized to connect the first auxiliary passage 51 to the suction side of the electric pump 25, and the electric pump 25 is driven to force-feed the liquid refrigerant in the auxiliary tank 50 to the water jacket 22. At the same time, the third solenoid valve 55 is also energized to open it, and the gas phase space 22
The injection port 22c at the top of the tank a is opened to the space of the auxiliary tank 50, that is, to the atmosphere. As a result, the refrigerant liquid level within the system gradually rises and the intruding air is discharged to the outside. This air bleeding operation continues until the liquid level in the system reaches a specified value, that is, when the liquid level reaches the level detected by the third liquid level sensor 58, the first and third solenoid valves 5
3, 55 and the electric pump 25 are stopped, and the process ends.

In addition, when this air is removed, the invading air is removed from the solenoid valve 5.
5 may be directly discharged into the atmosphere, but as described above, it is discharged directly from the solenoid valve 55 to the filler cap 50a via the auxiliary tank 50.
If the refrigerant is mixed in the intruding air, it can be captured in the auxiliary tank 50, so that loss of the refrigerant can be minimized.

In this way, if outside air has entered the cooling system, this air will be automatically removed after the engine is stopped or immediately after a cold start, and the performance of the cooling system will be maintained at a special level. Guaranteed for a long time without any administrative effort. Furthermore, when the key is off, the auxiliary tank 50 is not directly connected to the water jacket 22, but is also connected to the condenser 23, so heat builds up in the engine for a moment, increasing the temperature of the liquid, and the refrigerant in the water jacket 22 flows into the auxiliary tank 50. It also prevents the engine from becoming too hot due to backflow.

Next, we will explain the effect during cold engine starting.
The control circuit 30' detects that a cold start condition exists based on the temperature signal from the temperature sensor 32 and the energization state of the ignition system, and opens only the second solenoid valve 54.

The inside of the cooling system before starting is filled with the liquid phase refrigerant as described above, but when the engine 21 starts, the refrigerant is heated and vaporized, so the pressure inside the system increases, and the 13th As shown in the figure, the liquid phase refrigerant on the condenser 23 side is gradually pushed out to the auxiliary tank 50 through the second auxiliary passage 52. Therefore, the liquid level on the condenser 23 side gradually decreases, but during this time, the refrigerant is boiled and vaporized in the water jacket 22, so the liquid level in the water jacket 22 also decreases. However, when the liquid level falls below the position of the liquid level sensor 31, the electric pump 25 operates to replenish the liquid phase refrigerant, so the liquid level does not fall any further. Then, when the liquid level of the capacitor 23 decreases to such an extent that the second liquid level sensor 57 is exposed to the gas phase space, this is detected and the control circuit 3
0' restarts energization to the second solenoid valve 54 and closes it. As a result, the cooling system enters the state shown in FIG. 10, and thereafter performs its normal cooling function.

Note that during startup, as the refrigerant level in the system decreases as described above, the inside of the condenser 23 is in a liquid phase, so the amount of heat dissipated is significantly greater than when it is in a gas phase. Decrease. Therefore, the heat generated by the engine 21 does not wastefully escape to the outside, resulting in the advantage that the time required for warming up can be shortened.

By the way, in winter or when driving down a long slope, the amount of heat dissipated by the condenser 23 may exceed the amount of heat generated by the engine 21, causing the engine temperature to drop too much even if the electric fan 26 is stopped.

At such time of overcooling, the control circuit 30' determines the overcooling state based on the signal from the temperature sensor 32 since the engine temperature has fallen below a preset lower limit temperature, and starts the engine in the same way as at the time of starting. 2 Open the solenoid valve 54 and open the auxiliary tank 50 and refrigerant passage 28.
communicate with. During supercooling, the amount of refrigerant liquefied in the condenser 23 is greater than the amount of refrigerant vaporized in the water jacket 22, so the system has a negative pressure, and therefore the auxiliary tank 5
The liquid phase refrigerant will be introduced into the condenser 23 from zero. As a result, the refrigerant liquid level inside the condenser 23 rises, and the amount of heat released decreases accordingly, so the amount of heat generated by the engine increases relatively, and the engine temperature gradually rises, causing the engine to escape from the supercooled state. do. Note that when the engine temperature rises further after coming out of the supercooled state, the refrigerant in the condenser 23 is returned to the auxiliary tank 50 again based on the system internal pressure at this time, and the refrigerant liquid level in the lower tank 24 is detected by the liquid level sensor 57. When the temperature drops to this position, the second solenoid valve 54 is closed to return to the normal state.

As described above, according to the boiling cooling device of the second invention, by variably controlling the amount of liquid phase refrigerant in the cooling system according to the state of the engine, it is possible to prevent air from entering the system, promote warm-up, Since overcooling is prevented and even if air does enter, it is efficiently discharged, the reliability, stability, and maintainability of the cooling device are further improved.

h. Effects of the Invention In summary, according to the present invention, most of the engine water jacket is filled with liquid-phase refrigerant, and the interior of the condenser that liquefies the refrigerant vapor is basically maintained in a gas-phase state, thereby improving the heat dissipation state. In addition to increasing
The boiling point of the liquid phase refrigerant is controlled by changing the amount of cooling air to this highly efficient condenser via an electric fan, making it possible to significantly reduce the size and weight of the engine system.
The engine temperature can be quickly controlled to be appropriate depending on the operating condition, and therefore fuel efficiency can be effectively increased.

In addition, in the present invention, during normal operation of the cooling system after warming up, the cooling medium is sealed in the engine water jacket and condenser, and the pressure within the system is adjusted without exchanging pressure with the outside (closed loop). Since the temperature is controlled by the cooling medium, there is less risk of the cooling medium escaping into the atmosphere or drawing air into the system from the outside, making maintenance easier and ensuring long-term operation. This has the effect of maintaining stable cooling performance.

Furthermore, in the present invention, when negative pressure occurs in the system, liquid phase refrigerant is supplied from the external tank to prevent air from entering, and even if air does enter, it is possible to efficiently exhaust the air, so it is always possible to Good cooling efficiency can be achieved.

[Brief explanation of drawings]

1 to 3 are schematic configuration diagrams of different conventional examples. 4 to 9 relate to the first invention, and FIG. 4 is a schematic configuration diagram of an embodiment thereof,
Figure 5 is a characteristic diagram showing the relationship between engine rotation and the required wind speed to the condenser or radiator in comparison with the conventional one. Figure 6 is a characteristic diagram showing the relationship between engine rotation and the required amount of heat dissipation. FIG. 7 is a characteristic diagram showing the relationship between refrigerant temperature (engine temperature) and fuel consumption rate, and FIG. 8 is a pressure diagram showing changes in cylinder pressure of a diesel engine in comparison with a conventional one. 9 is a circuit configuration diagram of an example of a control system, FIG. 9A is an explanatory diagram showing the relationship between the injection pulse and the output of the ripple counter, and FIG. An explanatory diagram showing the relationship with the output characteristics, and FIG. C is an explanatory diagram showing the control characteristics of the refrigerant temperature. FIGS. 10 to 13 are schematic configuration diagrams of different operating states of each embodiment regarding the second invention. 21... Engine (main body), 22... Water jacket, 22a... Gas phase space, 22b... Refrigerant injection pipe, 23... Condenser, 24... Tank (lower tank), 25... Electric (supply) pump ,2
6... Electric (cooling) fan, 28... Refrigerant passage,
30... Control circuit, 31, 57, 58... Liquid level sensor, 32... Temperature sensor, 40... Electromagnetic fuel injection valve, 41... Ripple counter, 43... Smoothing circuit, 44, 46... Comparator , 50... Auxiliary tank, 51... First auxiliary passage, 52... Second
Auxiliary passage, 53...first solenoid valve, 54...second solenoid valve, 55...third solenoid valve.

Claims (1)

[Claims] 1. An engine water jacket filled mostly with liquid-phase refrigerant, a condenser that cools and liquefies refrigerant vapor from the engine water jacket, and temporarily stores the liquefied refrigerant from the condenser. A tank, a supply pump that returns the liquefied refrigerant from this tank to the water jacket, and a cooling fan that supplies forced cooling air to the condenser, detects the engine temperature, and uses this detection signal to adjust the refrigerant temperature in the engine to a predetermined value. The cooling system consists of a circuit that drives an electric fan and a control system that has a circuit that detects the refrigerant level in the water jacket and drives the supply pump until the level reaches a predetermined level when the level drops. During normal operation of the cooling system after warm-up, the refrigerant passage from the water jacket to the water jacket via the condenser is a closed loop, and the liquid phase refrigerant flows through the water jacket in this refrigerant passage under the condition that a predetermined liquid level is met. 1. A boiling cooling device for an engine, characterized in that the upper part of the inside of the bucket and substantially the entire inside of the condenser are filled with enough volume to form a gas phase space. 2. The boiling cooling system for an engine according to claim 1, wherein the predetermined value of the refrigerant temperature within the engine is changed depending on the engine operating condition. 3 An engine water jacket that is mostly filled with liquid phase refrigerant, a condenser that cools and liquefies the refrigerant vapor from this engine water jacket, a tank that temporarily stores the liquefied refrigerant from this condenser, and a tank that cools and liquefies the refrigerant vapor from this engine water jacket. A supply pump that returns liquefied refrigerant to the water jacket, a cooling fan that supplies forced cooling air to the condenser, and a cooling fan that detects engine temperature and uses this detection signal to drive the cooling fan to bring the refrigerant temperature inside the engine to a predetermined value. The cooling system consists of a circuit and a control system that has a circuit that detects the refrigerant liquid level in the water jacket and drives the supply pump until the liquid level reaches a predetermined level when the liquid level drops. During operation, the refrigerant passage from the water jacket to the water jacket via the condenser is a closed loop, and the liquid phase refrigerant flows inside the water jacket and above the condenser in this refrigerant passage under the condition that a predetermined liquid level is satisfied. In a boiling cooling device for an engine, in which an amount of liquid-phase refrigerant is enclosed so that almost the entire interior is a gas-phase space, an auxiliary tank storing liquid-phase refrigerant of at least the same capacity as the gas-phase space is disposed so as to be communicated with the refrigerant passage, When the cooling system is subcooled after warming up and after the engine has stopped, the negative pressure in the system supplies liquid phase refrigerant from the auxiliary tank to the refrigerant passage. When it is detected that there is no phase refrigerant, liquid phase refrigerant is supplied from the auxiliary tank into the refrigerant passage to replace the mixed air with liquid, and while the engine is warming up, the refrigerant level in the refrigerant passage reaches a predetermined value. A boiling cooling system for an engine, characterized in that liquid phase refrigerant in a refrigerant passage returns to an auxiliary tank, and communication between the tank and a supply pump is maintained during normal operation of the cooling system after warming up. 4. The auxiliary tank has a first auxiliary passage that can communicate with the refrigerant passage on the suction side of the pump and a second auxiliary passage that can communicate with the refrigerant passage on the tank side between the supply pump and the tank, and has a refrigerant passage on the suction side of the supply pump. The passage is the first
It selectively communicates with either the refrigerant passage on the tank side or the first auxiliary passage via a solenoid valve, the second auxiliary passage is opened and closed by the second solenoid valve, and the vicinity of the top of the refrigerant passage is connected to the atmosphere by a third solenoid valve. The second solenoid valve is opened or closed, and the second solenoid valve is opened when the cooling system is overcooled after warming up and after the engine has stopped, and when the engine is cold immediately after starting, it detects that there is no liquid phase refrigerant near the top of the refrigerant passage. Then, the first solenoid valve is switched to connect the first auxiliary passage and the supply pump suction side refrigerant passage, and the third solenoid valve is opened, so that the refrigerant liquid level in the refrigerant passage becomes a predetermined value while the engine is warming up. During normal operation of the cooling system after warming up, the second solenoid valve was opened to maintain communication between the tank and the supply pump via the first solenoid valve, and the second and third solenoid valves were closed. The evaporative cooling device for an engine according to claim 3, characterized in that: