JPH076384B2 - Boiling cooling device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling cooling apparatus for an internal combustion engine, which stores liquid phase refrigerant up to a predetermined level in a water jacket and cools each part of the internal combustion engine by boiling vaporization of the liquid phase refrigerant. In particular, the present invention relates to an improvement of a boiling cooling device of a type in which the system pressure is maintained at about atmospheric pressure via a reservoir tank open to the atmosphere.

Conventional technology The applicant of the present invention forms a closed-loop refrigerant circulation system mainly composed of a water jacket, a condenser, and a refrigerant supply pump, and guides the refrigerant vapor generated by the water jacket to a condenser to condense the liquid. Various boiling cooling devices have been proposed in which the coolant supply pump is actuated based on the detection of the surface sensor to replenish the water jacket again (for example, JP-A-60-36712 and JP-A-60-36715). No. In this device, an electric fan is used as a cooling fan for forcibly cooling the condenser, and the system temperature is controlled by adjusting the forced cooling air based on a temperature sensor provided in the water jacket.

The applicant has also proposed an atmospheric open-type boiling cooling device as a very simplified one without performing complicated temperature control (Japanese Patent Application No. 60-147814). In this system, the reservoir tank open to the atmosphere and the condenser lower tank are always in communication so that the inside of the system consisting of the condenser and water jacket is kept at approximately atmospheric pressure. Since the phase refrigerant can move freely, it is possible to keep the system temperature substantially constant while the liquid level position in the condenser naturally moves up and down so that the heat radiation amount of the condenser and the heat generation amount of the engine are balanced. And, in order to secure the condensation performance at the time of idling where the vehicle traveling wind is not obtained, also provided with an electric cooling fan,
For example, when the temperature of the refrigerant in the lower tank is high, the forced cooling air is supplied.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above open-air type boiling cooling device, the heat radiation of the condenser should be made with an appropriate allowance so that the heat radiation of the condenser may exceed the heat generation of the engine under various operating conditions. The design of the area is extremely rare, for example, when the heat dissipation capacity of the condenser is reduced due to a decrease in the boiling point of the refrigerant in highlands, when the outside temperature becomes extremely high, or when extremely high load operation is continued. If the conditions are overlapped, the amount of heat radiated from the condenser may be less than the amount of heat generated from the engine, and the refrigerant vapor may be jetted into the reservoir tank. Further, in order to completely prevent the vapor from being blown out, the condenser becomes very large.

Therefore, the present invention basically makes the cooling system open to the atmosphere, and when the heat radiation amount of the condenser is insufficient, the boiling point of the refrigerant is increased to increase the heat radiation amount of the condenser.

Means for Solving Problems A boiling cooling apparatus for an internal combustion engine according to the present invention is provided with a liquid level detecting means at a predetermined level, and a water jacket in which a liquid phase refrigerant is stored, and a refrigerant generated in the water jacket. A condenser in which vapor is introduced and the condensed liquid-phase refrigerant in the lower tank is stored, a refrigerant supply pump that replenishes the liquid-phase refrigerant condensed by the condenser to the water jacket, and the liquid level detection means for detection. Based on this, pump control means for controlling the refrigerant supply pump so as to keep the liquid level position in the water jacket at a predetermined level and the lower tank are always in communication with the lower tank so that the liquid-phase refrigerant freely moves between the lower tank and the lower tank. And a first temperature for detecting the refrigerant temperature in the water jacket and the reservoir tank opened to the atmosphere through the atmosphere communication passage A sensor,
There is a predetermined temperature difference between the second temperature sensor that detects the refrigerant temperature of the lower tank, the electromagnetic valve that is disposed in the atmosphere communication passage and that closes the atmosphere communication passage, and the temperature detected by the first and second temperature sensors. When the value is larger than the value, keep the solenoid valve open,
And a solenoid valve control means for closing the valve when it is below a predetermined value.

Action Under normal operating conditions, the amount of heat radiated by the capacitor is secured to be larger than the amount of heat generated by the engine, so the temperature difference between the first and second temperature sensors, which indicates the degree of subcooling in the capacitor, is sufficiently large. Therefore, the solenoid valve is in the open state and the inside of the reservoir tank is open to the atmosphere, so the internal pressure of the condenser, water jacket, etc. is maintained at approximately atmospheric pressure, and the engine temperature is maintained without special temperature control. Is maintained stable. on the other hand,
When the amount of heat radiated from the condenser becomes relatively small with respect to the amount of heat generated by the engine due to various bad conditions, the degree of supercooling in the condenser becomes small and the temperature of the refrigerant in the lower tank rises. Then, when the temperature of the refrigerant in the water jacket, that is, the temperature difference between the temperature of the refrigerant and the temperature of the refrigerant boiling at approximately atmospheric pressure becomes equal to or less than a predetermined value, the solenoid valve closes. Due to the closing operation of the solenoid valve, the internal pressure rises to some extent and the boiling point of the refrigerant rises. Therefore, the heat radiation amount in the limited heat radiation area of the capacitor increases. This allows
The amount of heat dissipated by the capacitor and the amount of heat generated by the engine are again in equilibrium. After that, when the detected temperature difference becomes large due to a decrease in engine heat generation amount or the like, the solenoid valve is opened again.

Embodiment FIG. 1 shows an embodiment of a boiling cooling apparatus according to the present invention, in which 1 is an internal combustion engine equipped with a water jacket 2 and 3 is a condenser for condensing a vapor phase refrigerant. Reference numerals 4 and 5 denote electric refrigerant supply pumps, respectively.

The water jacket 2 is formed over both the cylinder block 5 and the cylinder head 6 so as to surround the cylinder of the internal combustion engine 1 and the outer peripheral portion of the combustion chamber. The cylinders communicate with each other, and a plurality of steam outlets 7 are provided at appropriate positions above the cylinders. The steam outlets 7 are collected by a steam manifold 8 having a gas-liquid separation function, and then communicate with an upper inlet 3a of the condenser 3 via a steam passage 9. In addition, 10 is a refrigerant recovery passage for returning the liquid-phase refrigerant captured by the gas-liquid separation to the water jacket 2.
In addition, a float type liquid using a load switch, for example, which outputs an ON / OFF signal depending on the presence or absence of the liquid phase refrigerant at a predetermined level of the water jacket 2, specifically, at a substantially intermediate height position on the cylinder head 6 side. A surface sensor 11 is provided, and a first temperature sensor 12 including a thermistor or the like is provided below the surface sensor 11, that is, at a position where the surface sensor 11 is normally immersed in the liquid phase refrigerant.

The condenser 3 is an upper tank 13 having the inlet 3a.
And a core portion 14 mainly composed of a fine tube along the vertical direction, and a lower tank 15 for temporarily storing the liquid phase refrigerant condensed in the core portion 14, for example, a vehicle such as a vehicle front portion. It is installed at a position that can receive running wind, and on the front or back of it, an electric cooling fan 16 for forced cooling is installed.
Has been installed. Further, the lower tank 15 is provided with a second temperature sensor 17 including a thermistor or the like for detecting the temperature of the refrigerant inside thereof.

Reference numeral 21 denotes a reservoir tank disposed at a height position substantially equal to the set level of the liquid level sensor 11, which has an upper space open to the atmosphere via an atmosphere communication passage 22 and has a first It is connected to the lower tank 15 via the refrigerant circulation passage 23, and is connected to the water jacket 2 via the second refrigerant circulation passage 24 in which the refrigerant supply pump 4 is interposed.
Reference numeral 25 is a check valve that prevents the reverse flow of the refrigerant from the water jacket 2 to the reservoir tank 21. A normally open solenoid valve 26 is provided in the atmosphere communication passage 22.

Reference numeral 27 denotes a control device that controls the refrigerant supply pump 4, the cooling fan 16, and the solenoid valve 26, which is a so-called micro computer and performs a series of controls according to a predetermined program described later. There is.

Next, FIG. 2 is a flow chart showing the contents of the control executed by the control device 27, and the operation of the boiling cooling device constructed as described above will be explained below with reference to this flow chart. To do.

First, when the engine is stopped, the water jacket 2
The interior of the condenser 3 is filled with a liquid-phase refrigerant (for example, an ethylene glycol aqueous solution), and some liquid-phase refrigerant remains in the reservoir tank 21. When the engine is started in this state, the refrigerant in the water jacket 2 is in a stagnant state, so that the temperature rises quickly and boiling starts soon. Immediately after the start, the temperature T _E detected by the first temperature sensor 12 and the temperature T detected by the second temperature sensor 17 are naturally required.
_Although the temperature difference (T _E −T _C ) from _C is small, until the refrigerant temperature T _E in the water jacket 2 reaches 80 ° C. or higher, regardless of the temperature, the solenoid valve 26 is closed and the cooling fan 16 is closed. Is not performed (step 1).

When boiling begins, the pressure in the system increases due to the generated vapor pressure, and the lower tank 15 of the condenser 3 to the reservoir tank 21
The excess refrigerant is gradually pushed out, and the vapor phase refrigerant region expands to the upper part of the water jacket 2 and the upper part of the condenser 3. Then, when the liquid level of the refrigerant in the water jacket 2 drops below the set level of the liquid level sensor 11 due to boiling, the refrigerant supply pump 4 operates intermittently under the control of steps 15 to 17, and the water from the reservoir tank 21 is discharged. Supply liquid-phase refrigerant to the jacket 2. As a result, the liquid level of the refrigerant in the water jacket 2 is kept substantially constant until the engine is stopped.

In this embodiment, the liquid-phase refrigerant condensed in the condenser 3 is returned to the water jacket 2 via the reservoir tank 21, but the lower tank 5 of the condenser 3 is used.
It is also possible to directly supply the water from the water jacket 2.

Further, since the heat radiation capacity of the condenser 3 increases as the vapor phase refrigerant region expands above the condenser 3, the liquid level position of the condenser 3 is determined at a position where the heat radiation capacity and the engine heat generation amount are in equilibrium. In other words, the liquid surface position of the condenser 3 naturally moves up and down according to the load of the engine, the vehicle wind, etc., while keeping the engine temperature substantially constant. Since the internal pressure of the water jacket 2 and the like is maintained at about atmospheric pressure via the reservoir tank 21, the engine temperature is approximately the boiling point of the refrigerant under atmospheric pressure. Then, when the liquid level position in the condenser 3 is considerably lowered and the degree of supercooling is reduced when the load is high, specifically, when the temperature difference (T _E −T _C ) becomes 8 ° C. or less, the cooling fan starts operating. And forcibly cool the condenser 3 (step 2,
7). The operation of the cooling fan 16 depends on the temperature difference (T _E −
When T _C reaches 10 ° C, stop (Step 2,
9).

In this way, normally, cooling using boiling / condensation of cooling is performed with the solenoid valve 26 open. The flag in the flow chart corresponds to the open / closed state of the solenoid valve 26, where "0" indicates "open" and "1" indicates "closed".

On the other hand, if the heat radiation capacity of the condenser 3 falls below the heat value of the engine for some reason, the liquid level of the refrigerant in the condenser 3 is lowered to the maximum, and the degree of supercooling in the condenser 3 is reduced. Become. Then, the detected temperature difference (T _E −
When T _C ) falls below 4 ° C., the solenoid valve 26 is closed and the reservoir tank 21 is sealed (steps 2, 5). Therefore, the pressure inside the condenser 3 and the like rises and the boiling point of the refrigerant rises, so that the temperature of the refrigerant vapor flowing into the condenser 3 rises and the heat dissipation capability of the condenser 3 increases. As a result, the heat radiation capacity of the condenser 3 and the engine heat generation amount are rebalanced in a state where the engine temperature slightly rises, and the ejection of the refrigerant vapor or the excessive rise of the engine temperature is surely avoided. In the boiling state, the steam temperature on the inlet side of the condenser 3 and the refrigerant temperature in the water jacket 2 are substantially equal to each other. Therefore, if the temperature difference (T _E −T _C ) is used as described above, for example, at high altitude, Even when the boiling point of the refrigerant under atmospheric pressure decreases, it can be accurately detected that the liquid level of the refrigerant in the condenser 3 has dropped to the limit, and it is not necessary to allow an excessive margin.

Further, when the solenoid valve 26 is once closed as described above, the temperature T _EO of the refrigerant in the water jacket 2 at the moment of closing is stored (step 6), and the water jacket is changed due to changes in operating conditions. Refrigerant temperature T _{E in 2} is less than 3
The solenoid valve 26 is returned to the open state when the temperature is lowered by ° C. Incidentally, not Hakare an increase in heat dissipation by some failure or the like, the electromagnetic valve 26 is opened even when the refrigerant temperature T _E of the water-di burnt bracts 2 is excessively heated (e.g. 120 ° C.) (step 11, 13).

Further, after the engine is stopped, the above control is continued for a certain time (for example, 30 seconds) to prevent overheating after the engine is stopped (steps 18 to 20). Then, after a certain period of time, the power supply is turned off, and the series of control ends (step 21). This power OF
Due to F, the solenoid valve 26 is kept in the open state, so that the inside of the water jacket 2 and the condenser 3 is finally filled with the liquid phase refrigerant.

EFFECTS OF THE INVENTION As is clear from the above description, according to the boiling cooling apparatus for an internal combustion engine according to the present invention, in the system in which the system internal pressure is maintained at approximately atmospheric pressure via the reservoir tank, the condenser is excessively It is possible to reliably prevent ejection of refrigerant vapor and overheating of the engine without increasing the size. Also, since the solenoid valve is controlled based on the temperature difference between the refrigerant temperature in the water jacket and the refrigerant temperature in the condenser lower tank, the refrigerant liquid level in the condenser has dropped to near the limit without being affected by high or low atmospheric pressure. Can be accurately detected.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention, and FIG. 2 is a flow chart showing the contents of control in this embodiment. 1 ... Internal combustion engine, 2 ... Water jacket, 3 ... Condenser, 4 ... Refrigerant supply pump, 11 ... Liquid level sensor,
12 …… First temperature sensor, 15 …… Lower tank, 16 …… Cooling fan, 17 …… Second temperature sensor, 21 …… Reservoir tank, 22 …… Atmosphere communication path, 26 …… Solenoid valve, 27 …… Control apparatus.

Claims (1)

[Claims] 1. A water jacket in which liquid level detection means is provided at a predetermined level and a liquid phase refrigerant is stored, and a refrigerant vapor generated in the water jacket is introduced and condensed in a lower tank below. Is stored, a refrigerant supply pump that replenishes the liquid-phase refrigerant condensed by the condenser to the water jacket, and a liquid level position in the water jacket is maintained at a predetermined level based on the detection of the liquid level detection means. And a reservoir tank which is always in communication with the lower tank so that liquid-phase refrigerant can freely flow between the lower tank and pump control means for controlling the refrigerant supply pump, and which is open to the atmosphere through an atmosphere communication passage. A first temperature sensor for detecting the temperature of the refrigerant in the water jacket, and a second temperature for detecting the temperature of the refrigerant in the lower tank. Sensor and an electromagnetic valve disposed in the atmosphere communication passage and opening / closing the atmosphere communication passage, and the solenoid valve is opened when the temperature difference between the temperatures detected by the first and second temperature sensors is larger than a predetermined value. And a boiling cooling device for an internal combustion engine, which is provided with an electromagnetic valve control means for keeping the valve closed at a predetermined value and closing the valve at a predetermined value or less.