JPH0759887B2 - Boiling cooling system for automobile engine - Google Patents

Description

The present invention relates to a boiling cooling apparatus for an automobile engine, which cools the engine by utilizing latent heat of boiling vaporization of a refrigerant filled in a water jacket.

A conventional boiling cooling device for an automobile engine is disclosed in, for example, JP-A-56-32027. In the one described in this publication, a capillary structure made of porous metal such as foam metal, foam ceramic or metal fiber is installed so as to surround the outer wall of the cylinder bore of the cylinder block and the outer wall of the combustion chamber of the cylinder head. The evaporation chamber above the installation in the cylinder block of the body and the capillary structure is connected to a radiator (condenser) equipped with an electric fan. In the passage that connects the radiator and the cylinder block side installation part of the capillary structure,
A pump is provided for feeding the liquid refrigerant from the radiator to the capillary structure side.

The cooling medium in the installation portion of the capillary structure in the cylinder block is sent and held by the capillary structure to the combustion chamber, which is the heat source, and the entire circumference of the outer wall of the cylinder bore. Then, it is cooled by the electric fan and liquefied, and is sent to the capillary structure installation portion of the cylinder block by the pump, and such circulation is repeated to cool the cylinder block and the cylinder head.

The electric fan is controlled by the control device based on the output of the pressure sensor that detects the pressure in the evaporation chamber of the cylinder head, and the set value of the pressure signal is variable by the suction negative pressure sensor that detects the load of the engine. For example, when the load is low, the rotation of the electric fan is controlled to increase the cooling temperature to improve the thermal efficiency, and when the load is high, the rotation of the electric fan is controlled to decrease the cooling temperature to reduce the occurrence of knocking and suction efficiency. I am trying to improve.

In such a conventional boiling cooling device, it is necessary to maintain a supercooled state (a temperature sufficiently lower than the saturation temperature at which boiling starts) except near the top of the combustion chamber where the combustion chamber wall becomes the hottest. Not satisfied. If the supercooling degree is not provided, the refrigerant evaporates before it reaches the top of the combustion chamber wall where the combustion chamber wall becomes the hottest,
The capillary structure near the top of the combustion chamber is in a state where no liquid-phase refrigerant is present (dry-out), resulting in insufficient cooling of the combustion chamber wall.

Therefore, increase the cooling capacity of the radiator sufficiently,
Reducing the temperature of the refrigerant introduced to the capillary structure to about 70 ° C. is an essential requirement for establishing this cooling system. That is, the refrigerant having a large degree of supercooling with respect to the saturation temperature is guided to the capillary structure, and the capillary structure itself, except for the vicinity of the top of the combustion chamber where the combustion chamber wall becomes the hottest, also has a large degree of supercooling. To let it.

However, the temperature of the liquid phase refrigerant under supercooling conditions is
Even if the pressure of the atmosphere is changed, the temperature hardly changes. The reason is that by changing the pressure, the amount of evaporation generated from the surface of the liquid phase changes slightly,
Compared to boiling conditions, the amount of evaporation under supercooled conditions is very small, and the very small amount of evaporation means that the latent heat amount is small and the liquid phase by changing the pressure is small. The change in the temperature of the refrigerant is a negligible amount.

That is, in the conventional device in which a large part of the capillary structure covering the combustion chamber wall is placed in a supercooled state, the temperature of the combustion chamber wall is set to the target temperature when the pressure in the cooling system is changed. On the other hand, it is difficult to make them follow with good responsiveness.

Therefore, in the present invention, by making the capacity of the radiator (condenser) only to condense the vapor phase refrigerant into the liquid phase, all the refrigerant existing in the water jacket is brought to the saturation temperature, and the pressure in the cooling system is adjusted. By changing and maintaining the liquid level of the liquid-phase refrigerant in the water jacket constant, it is possible to make the temperature of the combustion chamber wall of the engine follow the target temperature according to the operating state with extremely high responsiveness. It is intended to provide a cooling device.

The present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. First, the structure will be described. 1 is an engine, 2 is a water jacket, 3 is a liquid level of cooling liquid, 4 is a liquid level sensor, 5 is a temperature or pressure sensor, 6 is a gas-liquid separator, 7 is a modulator, and 8 is Condenser, 9
Is a tank for storing liquid phase refrigerant, that is, cooling liquid, 10 is an electric pump,
Reference numeral 11 is a refrigerant return port, 12 is a throttle opening sensor, 13 is an ignition signal sensor, and 14 is an electric fan as a cooling fan.

Most of the inside of the water jacket 2 that covers the entire periphery of the combustion chamber wall of the engine 1 is filled with the liquid-phase refrigerant, and the space 15 above the liquid surface 3 is filled with the refrigerant vapor. Here, the combustion chamber wall includes the periphery of the cylinder bore. The liquid level sensor 4 issues a signal to the modulator 7 that prompts the operation of the electric pump 10 so as to keep the level of the liquid level 3 above the entire wall of the combustion chamber. Refrigerant vapor generated by boiling from the heat transfer surface such as the wall surface of the combustion chamber enters the condenser 8 via the gas-liquid separator 6, where it is condensed and temporarily stores the liquid-phase refrigerant in the tank 9. From here, the refrigerant liquid is returned to the water jacket 2 via the return port 11 by the electric pump 10.

The condenser 8 is cooled by the electric fan 14, and the electric fan 14 is operated by the operation signal of the modulator 7. The modulator 7 is a temperature sensor (pressure sensor) 5
The temperature (pressure) of the cooling system detected by the engine, the signal of the engine operating state detected by the throttle opening sensor 12 and the ignition pulse sensor (or the engine speed sensor) 13, or the signal such as the suction negative pressure are input. ing.

Next, the operation will be described.

As shown in FIG. 2, in the urban driving region I, that is, in the portion where the engine rotation speed is low and the torque is larger than the flat road traveling resistance curve L, the amount of heat lost by increasing the cooling temperature of the engine is reduced to reduce fuel consumption. There is a demand for improvement. In addition, high-load operating areas such as climbing and towing II
In other words, in the vicinity of the full-open torque curve F and in the high-speed driving range II, that is, in the portion where the torque is higher than the flat road driving curve L at the high engine speed, the coolant temperature is lowered to prevent engine failure rather than fuel consumption improvement, and detonation is performed. (Abnormal combustion)
There is a demand to prevent the seizure of pistons and pistons.

Therefore, the present invention utilizes the boiling evaporation heat of the cooling liquid for engine cooling.At that time, the boiling point changes depending on the pressure, and the decrease in heat capacity is achieved by cooling the engine with a low circulation amount utilizing latent heat. Focusing on this, it aims to control the temperature of the coolant and promote warm-up.

That is, in FIG. 1, when the liquid level 3 does not reach the level of the liquid level sensor 4, the signal from the sensor reaches the electric pump 10 via the modulator 7 and operates it, so that the refrigerant in the tank 9 is Water jacket 2 through return port 11
Return to the inside and its level will rise and pump at the predetermined level 10
Will stop.

When the liquid level 3 of the liquid-phase refrigerant in the water jacket 2 is kept constant at the level of the liquid level sensor 4, that is, above the entire combustion chamber wall, the evaporation amount under the boiling condition becomes stable, and the combustion chamber becomes stable. It is possible to make the wall temperature constant with respect to the target temperature. In other words, considering that the latent heat quantity of the liquid-phase refrigerant is, for example, 600 kcal / kg, and heating 1 g of water by 1 ° C is 1 kcal / kg, the latent heat quantity is very large, so the combustion chamber wall temperature In order to make the temperature constant with respect to the target temperature, it is important to keep the liquid level of the liquid phase refrigerant in the water jacket 2 constant and to keep the evaporation amount of the refrigerant constant under boiling conditions.

When the engine operates, the refrigerant in contact with the wall surface of the combustion chamber is heated, its temperature rises, and then it boils. While the wall surface is cooled by the heat of evaporation, the refrigerant becomes vapor and rises in the liquid to escape into the space 15 to be separated by the gas-liquid separator 6 and sent to the condenser 8. The steam is cooled here and stored in the tank 9.

When vaporization becomes vigorous and the vapor temperature or pressure rises and exceeds a specified value, the temperature or pressure sensor 5 detects the temperature or pressure, and a command is issued via a modulator 7 to an electric fan.
It is sent to 14, which is rotated to reduce the temperature or pressure of the refrigerant. In this case, temperature control is as follows. First, to maintain the specified value.

In FIG. 3, the electric fan 14 is turned on when the steam temperature T is higher than the target control temperature that is determined by the engine operating state, that is, the specified value T ₀ , and is turned off when it is low.
N-OFF is repeated to bring the temperature T close to the specified value T ₀ .

Next, when changing the specified value.

When the throttle opening sensor 12 and the ignition signal sensor 13 detect the region where the engine is operating in the urban area I, the command is sent to the electric fan 14 via the modulator 7 to set the specified value T ₀ to 119 ° C. Then, the internal pressure becomes 1.9ata. In this case, the ON-OFF time ratio of the electric fan 14 can be obtained by lengthening the OFF time. In the region I, since the temperature of the cooling system is high as described above, the heat radiation amount for cooling is small, and the loss is accordingly small, so that the fuel efficiency is improved.

In addition, in the case of high load operation area III and high speed operation area II,
Contrary to the above, the time for energizing the electric fan 14 is lengthened. Then, the condenser 8 is liquefied and the inside of the system becomes a negative pressure, for example, the pressure becomes 0.5ata, and the temperature T ₀ becomes 80 ° C. The specified value in this case may be 80 ° C or lower. In the regions II and III, since the specified value is maintained at such a low temperature, heat is radiated actively, and as a result, cooling efficiency is increased and abnormal combustion such as knocking and piston burning are prevented.

In the normal medium speed range other than the above operation, set the specified value T ₀ to 100 ° C. In that case, the absolute system pressure is 1ata.

In the above embodiment, the entire combustion chamber wall is submerged below the liquid surface of the liquid phase refrigerant, all the liquid phase refrigerants existing in the water jacket 2 are brought to the saturation temperature, and cooling is performed by the latent heat of boiling vaporization. Therefore, when the pressure in the cooling system is changed, the temperature of the refrigerant surrounding the combustion chamber wall immediately changes to the saturation temperature corresponding to the pressure of the cooling system because all the refrigerant in contact with the combustion chamber wall has reached the saturation temperature. However, the temperature of the combustion chamber wall can follow the target temperature with extremely high responsiveness.

Further, since the entire combustion chamber wall is below the liquid surface of the liquid-phase refrigerant, it is not necessary to give the liquid-phase refrigerant a sufficient degree of supercooling with respect to the saturation temperature. Is small enough to condense into the liquid phase.

FIG. 4 is a waveform diagram of a current supplied to the electric fan 14 according to another embodiment.

In this embodiment, as the difference between the specified value T ₀ and the temperature detected by the temperature sensor 5 is larger, the energizing current sent to the electric fan 14 via the modulator 7 is increased to improve the cooling accuracy. In this case, the intensity of the current is formed into a mountain shape as shown in the figure by a known time constant utilization method. In the case of the square ON-OFF type shown in FIG. 3, the electric fan 14 suddenly starts to rotate, which may cause noise. However, in the method shown in FIG. 4, the electric fan 14 can be driven smoothly. Because it is done, such a thing will disappear.

In the present invention, as a method of maintaining the temperature or pressure at a specified value, and as a method of changing the specified value according to operating conditions, a method of changing the amount of electricity supplied to the condenser cooling electric fan is adopted. In this case, the method of changing the ON-OFF time ratio of the current while keeping the current strength constant,
A method of changing the intensity of current with a constant time ratio, and
Any method of changing both the time ratio and the strength of the current can be adopted.

As described above, according to the present invention, the configuration is such that the engine is cooled by using the latent heat of the refrigerant,
On the other hand, the target control temperature, that is, the specified value, is set according to the operating condition of the engine, and the system is designed to blow air to the condenser so that the temperature or pressure is reached. Therefore, it is possible to improve fuel efficiency and avoid detonation and seizure of piston at high speed or high load.

Further, the entire combustion chamber wall is submerged below the liquid surface of the liquid phase refrigerant, and all the refrigerant existing in the water jacket is set to a saturation temperature,
Since it tries to cool by the latent heat of vaporization by boiling, when the pressure in the cooling system is changed, the temperature of the refrigerant surrounding the combustion chamber wall reaches the saturation temperature because all the refrigerant in contact with the combustion chamber wall has reached the saturation temperature. Immediately changes to the saturation temperature corresponding to the pressure of the cooling system, and the temperature of the combustion chamber wall can follow the target temperature with extremely high responsiveness.

Since the entire combustion chamber wall is below the liquid surface of the liquid-phase refrigerant, it is not necessary for the liquid-phase refrigerant to have a sufficient degree of supercooling to the saturation temperature. It only requires a small capacity to be condensed into.

The latent heat of liquid phase refrigerant is, for example, 600 kcal / kg, and 1 g of water is 1
Considering that heating at 1 ° C is 1 kcal / kg, the latent heat amount is very large, so the liquid level of the liquid phase refrigerant in the water jacket is kept constant above the entire combustion chamber wall. As a result, the evaporation amount under the boiling condition becomes stable, and the combustion chamber wall temperature can be made constant with respect to the target temperature.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the system configuration of the present invention, FIG. 2 is an engine operating state diagram for explaining the control range of the present invention,
FIG. 3 is a characteristic diagram of ON-OFF control with respect to the electric fan, and FIG. 4 is a conduction current waveform diagram with respect to the electric fan showing another embodiment. Explanation of symbols appearing in the drawings 1 ... Engine 2 ... Water jacket 3 ... Liquid level 4 ... Liquid level sensor 5 ... Temperature or pressure sensor 6 ... Gas-liquid separator, 7 ... Modulator 8 ... Condenser 9 …… Tank for storing liquid refrigerant 10 …… Electric pump, 11 …… Refrigerant liquid return port 12 …… Throttle opening sensor 13 …… Ignition signal sensor, 14 …… Electric fan

Claims (1)

[Claims] 1. A water jacket is provided around the entire wall of a combustion chamber, and most of the water jacket is filled with a liquid phase refrigerant so that the entire combustion chamber wall is submerged below the liquid surface of the liquid phase refrigerant. In a boiling cooling device for an automobile engine in which all of the existing liquid-phase refrigerant reaches a saturation temperature corresponding to the pressure in the cooling system to cool the combustion chamber wall, a condenser for cooling the vapor from the water jacket, and the condenser A cooling fan that blows air, a temperature or pressure sensor that detects the temperature or pressure of the refrigerant in the cooling system, an operating state detection unit that detects the operating state of the engine, and the liquid level of the liquid-phase refrigerant in the water jacket. Liquid level sensor,
A refrigerant pump that sends the liquid-phase refrigerant condensed in the condenser to a water jacket, outputs a drive signal to the cooling fan by the output of the temperature or pressure sensor and the operating state detection means, and outputs the drive signal by the output of the liquid level sensor. Provided with a modulator that outputs a drive signal to the refrigerant pump,
When the refrigerant temperature or pressure is equal to or higher than a specified value, the cooling fan is driven to control the refrigerant temperature or pressure to a specified value, and the specified value is changed according to the operating state of the engine, and the refrigerant pump is driven. A boiling cooling device for an automobile engine, wherein a liquid surface position of a liquid-phase refrigerant in a water jacket is controlled to be constant.