JPS6119921A - Boiling medium cooling device in engine - Google Patents

Abstract

PURPOSE:To prevent a closed-loop cooling system from being subjected to vacuum, by opening a shut-off valve when the system becomes under vacuum, so that coolant is introduced from an auxiliary tank. CONSTITUTION:There is provided an auxiliary tank 19 connected to a water jacket 2 through auxiliary passages 15, 16 and solenoid valves 17, 18. Upon stopping of an engine, the auxiliary passage 15 is opened to introduced coolant reserved in the auxiliary tank 19 upto the detection level of a liquid level sensor 20 by use of the pressure differential between the system pressure which has lowered and the atmospheric pressure. With this arrangement, the system may be prevented from being subjected to vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a boiling cooling device for an engine that utilizes the latent heat of vaporization of a coolant.

(Prior Art) The present applicant has proposed a boiling cooling device that boils and evaporates the coolant in a water jacket and uses the latent heat of vaporization to efficiently cool the engine (Japanese Patent Application No. 145,467/1989). This will be explained based on Fig. 3. 1 is the engine body, 2 is the cylinder block 3.
and water marks 1 to 1 formed over the cylinder head 4. 5 is a cooling liquid (refrigerant) filled in the upper part of the water jacket 2 leaving a predetermined space.

When the coolant 5 absorbs heat from the engine and reaches a predetermined temperature, it begins to boil and evaporates while taking away latent heat of vaporization.

Then, this evaporative cooling liquid (steam) is led to a condenser 7 for heat exchange via a steam passage 6 connected to the upper part of the water jacket 2.

A fan (electric fan) 8 that sends cooling air to the condenser 7
is installed, and the evaporative cooling liquid is cooled by radiating heat to the outside according to the air volume, and after being condensed to the original liquid, it is stored in the zero-wattage tank 9.

A liquid level sensor 10 is installed in the water jacket 2,
When the liquid level drops to a certain extent as the coolant 5 evaporates, the control circuit 11 drives the supply pump 13 interposed in the return passage (refrigerant passage) 12 of the water Vette 2 . The pump 13 circulates the coolant 5 in the lower tank 9 to the jacket 2 via the solenoid valve 25, thereby forming a closed circuit cooling system.

Further, the control circuit 11 drives and controls the cooling fan 8 based on signals from a humidity sensor 14 that detects the coolant temperature and various sensors (not shown) that detect engine rotation, accelerator opening, fuel supply m, etc. Then, the engine cooling temperature is set to the optimum temperature according to the operating conditions. In other words, since the inside of the cooling system is a closed circuit, the boiling point of the cooling liquid can be raised or lowered by changing the pressure inside the system.

For example, at low loads when the engine generates relatively little heat, the cooling fan 8's ffl is reduced to suppress heat dissipation and condensation in the condenser 7 to some extent, and the pressure within the cooling system is increased to above atmospheric pressure. Increase the boiling point of liquid 5. This maintains the engine coolant temperature at a high level (for example, 120° C.) to reduce cooling loss.

On the other hand, at high loads when the engine generates a lot of heat,
Increase the air flow of the cooling fan 8 to dissipate heat from the condenser 7,
Condensation is promoted, and the pressure in the system becomes below atmospheric pressure, lowering the boiling point of the coolant 5, keeping the engine coolant temperature at a low level (for example, 90° C.), and ensuring a good cooling state.

The boiling latent heat of vaporization of the coolant 5 is extremely large, and the heat dissipation effect of the evaporative coolant in the condenser 7 is sufficiently high. Therefore, the engine can be efficiently cooled with a small amount of the coolant 5, and the cooling temperature can be lowered. It is possible to control responsively according to operating conditions, and therefore provides excellent cooling performance.
111 functions can be obtained.

On the other hand, with this type of equipment, when the engine is stopped and the coolant temperature drops to near room temperature, the coolant that had been evaporating will liquefy and the pressure in the system will drop considerably.
Strong negative pressure may occur.

Therefore, the auxiliary passage 15.16 and the solenoid valve 17.18
Auxiliary tank 1 connected to A-tajitoket 2 via
9 is installed, the auxiliary passage 15 is opened when the engine is stopped, and the supplementary coolant stored in the auxiliary tank 19 is transferred to the liquid level sensor Fj20 by using the differential pressure between the reduced system pressure and atmospheric pressure.
be introduced to the detection level.

Further, in order to eliminate air from the outside when it enters into the jacket 1 and 2 due to a drop in the system pressure, a solenoid valve 22 is provided in the upper part of the steam passage 6, such as an air passage 21. Air passage 21 during the initial stage of engine startup, etc.
The auxiliary passage 16 is opened and the supply pump 13 is driven to forcibly feed the cooling liquid from the auxiliary tank 19 and exhaust excess air. This air is led to the upper air layer of the auxiliary tank 19 and discharged to the outside via the filter 23.

In this state, when the temperature of the coolant increases due to engine startup and reaches a predetermined temperature, the coolant starts to boil and evaporate.
The auxiliary passage 15 is opened according to the detection level, the coolant is boiled and evaporated by hand, and the compensated amount of coolant is pushed back to the auxiliary tank 19 by the evaporation pressure.

In this case, the supply pump 13 is driven according to the liquid level sensor 10, and sends the cooling liquid from the lower tank 9 to the jacket 1 so as to maintain the liquid level in the jacket 2 at an appropriate level, so that the liquid level in the lower tank 9 reaches a predetermined level. Then I'll be f'lled.

This allows the amount of coolant in the system to be restored and set to an appropriate level while maintaining the evaporation pressure at atmospheric pressure. Therefore, air is prevented from entering the system, and the heat exchange efficiency of the capacitor 7'i is maintained at a favorable Q.

In this way, an accurate cooling effect of boiling cooling is always obtained, and its high cooling performance is maintained, and the boiling point pressure of the cooling liquid can be arbitrarily lowered to below atmospheric pressure depending on the equipment of the cooling fan 8. By lowering the cooling temperature, as mentioned above, it is possible to set the cooling temperature to 100°C or less (when using water) when the engine is under high load.

In addition, with the Juki device, the engine can be cooled with a small amount of cold fJI fluid, so not only the water jacket 2 but also the
The condenser 7, supply pump 13, etc. are also small and compact, making it possible to reduce the size and weight of the cooling system.

In addition, it is possible to shorten the warm-up time of the engine, and since the heat dissipation efficiency of the condenser 7 is good, the driving power of the cooling fan 8 can be reduced, thereby improving noise and fuel efficiency. There are advantages.

(Problems to be solved by the invention) However, in this device, four steps are required to control the flow of refrigerant.
There is a problem in that the three solenoid valves 17, 18, 22, and 25 are required, which complicates the system configuration.

Furthermore, when the amount of refrigerant in the closed circuit returns to the specified value after the engine warms up, communication with the auxiliary tank 19 is completely cut off.
When the pressure inside the closed circuit becomes negative due to supercooling, outside air may be sucked into the closed circuit little by little due to this negative pressure. There was also the problem that:

The present invention aims to solve such problems 1-1.

(Means for Solving the Problems) The present invention provides a method for solving the problems in which
- The capacitor jacket and the condenser, whose interior is kept in a vapor phase, are connected by a vapor passage in the upper part through which refrigerant vapor passes, and a refrigerant passage in which the liquefied refrigerant from the condenser is returned via a supply pump, while the refrigerant in the lower part of the condenser is A lower tank is installed to temporarily store water, a passage is provided that communicates from this lower tank or its vicinity to an external auxiliary tank, and a shutoff valve is interposed in the middle of this communication passage, while sensing the internal pressure of water jackets 1 to 1. and a control circuit for opening the cutoff valve when the internal F[ is lowered.

(Function) Therefore, in the present invention, the cooling circuit is filled with refrigerant in advance so that no air remains, and after starting the first engine, the shutoff valve is activated, and the generated vapor pressure pushes the excess refrigerant back to the auxiliary tank. By closing the isolation valve, an open circuit boiling cooling cycle can be constructed.

When the pressure inside the closed circuit becomes negative, the shutoff valve opens and sucks refrigerant from the auxiliary tank.

Therefore, negative pressure in the system can be reliably prevented even when the engine is running or stopped.

(Example) FIG. 1 shows an embodiment of the invention.

A communication passage 30 branches off from the lower tank 9 of the condenser 7, and this communication passage 30 is connected to an auxiliary tank 32 having a vent hole 36 via a shutoff valve 31. Shut off? 31 is a normally open electromagnetic valve that closes when energized, and is activated by a signal from the control circuit 11.

In order to sense the internal pressure of the open circuit, a pressure switch 33 is provided to detect the pressure in the steam passage 6, and this pressure switch 33 operates in conjunction with a diaphragm 34 to ensure that the internal steam pressure is below (external pressure p + 10 mm) - IQ). Therefore, when the pressure inside the system becomes negative, the signal is input to the control circuit 11.

When the pressure switch 33 becomes OFI <L, the control circuit 14
The shutoff valve 31 is opened to suck refrigerant into the system from the auxiliary tank 32.

Note that a refrigerant method inlet 35 is provided above the steam passage 6, from which the refrigerant is first filled into the system.

The present invention is constructed in this way, and when compared with FIG.
．． 25, the auxiliary tank 321 is connected to the lower tank only through the communication path 30.

First, when injecting the refrigerant, remove the cap of the refrigerant injection [35] and fill the system with liquid phase refrigerant so that no air remains in the system. At this time, either close the communication passage 30 to prevent the refrigerant from flowing out from the communication passage 30 to the auxiliary tank 32, or close it by energizing the cutoff valve 31 a3.

Once the system is filled with refrigerant, cool IJ1. Turn the injection port 35 on.
Seal with 7 taps. Note that a small amount of spare refrigerant is injected into the auxiliary tank 32.

In this case, by positioning the auxiliary tank 32 upward so that the liquid level in the auxiliary tank 32 is equal to or higher than that of the refrigerant inlet 35, the refrigerant in the system will be prevented from flowing into the auxiliary tank 32 due to vibrations, etc. It can be prevented.

The refrigerant is filled in this way, and when the engine is started and warmed up, the refrigerant in the water jacket 2 boils and its vapor pressure begins to increase, causing the control circuit 11 to open the shutoff valve 31. The valve is kept open, so that the internal pressure forces the refrigerant into the auxiliary tank 32 via the communication passage 30.

When the liquid level H2 in the water jacket 2 drops to the level detected by the liquid level sensor 10 due to evaporation, the control circuit 11 drives the supply pump 13 to feed the refrigerant in the condenser 7 into the water jacket 2.

On the other hand, since the refrigerant is pushed back from the lower tank 9 of the condenser 7 by internal pressure via the communication path 30, the liquid level gradually decreases, and the liquid level sensor 24 detects the liquid level H.
7 is detected, the control circuit 11 energizes the cutoff valve 31 to close it, forming a closed circuit cooling system.

In this way, excess refrigerant is pushed out from within the system to the auxiliary tank 32, securing a predetermined evaporation space above the water jacket 2 and keeping the inside of the condenser 7 in a gas phase space.

In this case, only refrigerant vapor exists in the space within the system, and there is no air at all.

From now on, the detected temperature of the temperature sensor 14 and the liquid level sensor 10 will be explained.
Based on the detected liquid level, the control circuit 11 controls the rotation of the cooling fan 8 of the condenser 7 and the drive of the supply pump 13, thereby performing appropriate and responsive engine cooling by boiling cooling.

By the way, when the load is small, such as during deceleration operation of the engine, and the generation of refrigerant vapor is insufficient for heat exchange in the condenser 7, the pressure in the system decreases to below atmospheric pressure.

However, in such a case, the pressure switch 33 is turned off.
Therefore, the control circuit 11 opens the cutoff valve 31.

Therefore, the refrigerant is sucked in from the auxiliary tank 32 in response to the decrease in system pressure, and the liquid level rises to, for example, H3.

Therefore, the pressure inside the system does not drop below the outside pressure, and while this prevents low-temperature boiling from occurring due to the drop in internal pressure and overcooling of the engine, it also prevents outside air from leaking from the joints of each pipe. This prevents the heat exchange rate from decreasing in the condenser 7 caused by air entering the system.

On the other hand, when the engine stops, the control circuit 11
Cut off the current to 1 and open the valve.

After the engine stops, the system cools down and the steam condenses, but
The degree of vacuum in the space tends to increase, but when the shutoff valve 31 opens, liquid phase refrigerant is sucked in from the auxiliary tank 32, and eventually the system is completely filled with refrigerant, returning to the state before the engine was started. .

Next, to explain the embodiment shown in FIG. 2, this is equipped with an expandable tank 42 as an auxiliary tank 32 whose volume is variable depending on the internal pressure.In this way, the refrigerant in the expandable tank 42 comes into contact with the outside air. This prevents air bubbles from being dissolved in the refrigerant while the vehicle is running, reliably prevents air from entering the system, and prevents loss of refrigerant due to evaporation.

(Effects of the Invention) As described above, according to the present invention, the inside of the system and the auxiliary tank are
It only needs to be connected through a single communication path and solenoid valve (shutoff valve), which simplifies system configuration and control. By sucking refrigerant from the tank, it is possible to reliably prevent overcooling of the engine and air from entering the system.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view of a main part of the second embodiment, and FIG. 3 is a configuration diagram of a conventional example. ″ 1...Engine body, 2...Waterage (Ikerato), 6...Steam passage, 7...Condenser, 8...Cooling fan, 9...Lower tank, 10.24...Liquid Surface sensor, 11... Control circuit, 12... Refrigerant passage, 1
3... Supply pump, 30... Communication path, 31... Shutoff valve, 32... Auxiliary tank, 35... Refrigerant inlet. Special Applicant Nissan Motor Co., Ltd. Agent Patent Attorney Masaki Yu Fuji □4-',, + Figure 1

Claims (1)

[Claims] The engine water jacket, which is mostly filled with liquid-phase refrigerant, and the condenser, which maintains the interior in a gas phase, are connected by a vapor passage in the upper part through which refrigerant vapor passes, and a refrigerant passage, in which the liquefied refrigerant from the condenser is returned via a supply pump. On the other hand, a lower tank for temporarily storing refrigerant is provided at the bottom of the condenser, a passage is provided from this lower tank or its vicinity to an external auxiliary tank, and a cutoff valve is interposed in the middle of this communication passage. 1. A boiling cooling system for an engine, comprising a control circuit that includes means for sensing the internal pressure of the jacket and opens the shutoff valve when the internal pressure decreases.