JPH06102976B2 - 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 cools by utilizing latent heat of vaporization of a liquid phase refrigerant stored in a water jacket.

2. Description of the Related Art As a cooling device for an automobile engine or the like, instead of a conventional water cooling type cooling device, there is a boiling cooling device with a cycle of boiling and condensing a refrigerant (cooling water), for example, Japanese Patent Publication No. 57-57608. As described in Japanese Laid-Open Patent Publication No. 57-62912, the liquid level in the water jacket is adjusted by a natural circulation method using the own weight of the cooling water. It is not reliable and safe because it cannot be expected to secure it and there is a risk of overheating due to exposure of high temperature parts to the gas phase.

On the other hand, the applicant has proposed various boiling cooling devices in which the coolant liquid level in the water jacket is controlled to a predetermined level by using a coolant supply means, for example, a coolant supply pump (for example, Japanese Patent Laid-Open No. Sho 60). -36712, JP-A-60-36715, JP-A-60-243321, etc.). This is a refrigerant circulation system mainly composed of a water jacket, a condenser, a refrigerant supply pump, etc., and is equipped with a liquid level sensor corresponding to the set level of the water jacket. (For example, an ethylene glycol aqueous solution) is stored, and each part is cooled by the vaporization by boiling. Then, the generated steam is guided to a condenser, condensed, and collected as a liquid-phase refrigerant in the lower part of the condenser, and then turned on and off based on the detection signal of the liquid level sensor.
The working coolant supply pump circulates and supplies the water jacket again to maintain the liquid level of the coolant at the set level. In this way, by forcibly controlling the coolant liquid level in the water jacket using the coolant supply pump, it is possible to reliably maintain the liquid level at the set level even if the load conditions etc. change. It is possible to prevent the exposure of isothermal parts and to secure an appropriate steam space above the water jacket, thereby exhibiting stable cooling performance. In addition to this, a mechanical pump and a solenoid valve that are constantly driven by the engine output are used as the refrigerant supply means,
There is also one in which the liquid level of the refrigerant in the water jacket is similarly controlled by opening and closing the electromagnetic valve based on the detection signal of the liquid level sensor.

Problems to be Solved by the Invention As described above, the refrigerant liquid level in the water jacket is controlled by the ON / OFF operation of the refrigerant supply pump and the solenoid valve. Hysteresis is provided during switching. Here, the hysteresis is the dead zone, that is, the difference between the liquid level position where the pump turns on when the liquid level goes down and the liquid level position where the pump turns off when the liquid level goes up. Although it indicates the range, in reality, a single reference liquid level is set by the liquid level sensor, so the pump is turned on when the liquid level sensor's OFF state (state below the reference level) continues for a predetermined time. Along with the operation, the control program is configured to stop the pump when the liquid level sensor is in the ON state (state above the reference level) for a predetermined time. Controls hunting. That is, the length of the above-mentioned predetermined time corresponds to the magnitude of hysteresis.

However, in the above conventional boiling cooling device, the hysteresis is determined by the response of the liquid level sensor and the like, and is always constant.

Therefore, if the hysteresis is set to be relatively small, the refrigerant supply pump and the electromagnetic valve are operated more frequently, and the durability is impaired. Especially in an electric pump using a DC motor, the wear of the brush becomes remarkable. Conversely, if the hysteresis is set to a relatively large value, a large amount of low-temperature liquid-phase refrigerant will be supplied to the water jacket at one time when the temperature of the liquid-phase refrigerant in the lower part of the capacitor is low, such as in winter when the capacity of the capacitor is low. As a result, hunting of the temperature in the water jacket becomes large, and when the refrigerant in the water jacket is used as the heat source of the heater for heating the vehicle compartment, the heater blowout temperature becomes unstable.

Means for Solving the Problems In order to solve the above problems, the present invention variably sets the hysteresis according to the refrigerant temperature on the condenser side. That is, the boiling cooling apparatus for an internal combustion engine according to the present invention has a water jacket 1 having a vapor outlet in the upper part and in which a liquid-phase refrigerant is stored,
The condenser 2 into which the refrigerant vapor generated in the water jacket 1 is introduced and the condensed liquid phase refrigerant is collected in the lower part, and the refrigerant supply means for supplying the liquid phase refrigerant condensed in the condenser 2 to the water jacket 1. 3, a temperature sensor 4 for detecting the liquid-phase refrigerant temperature below the condenser 2, and a liquid level sensor 5 provided in the water jacket 1 for detecting whether or not the liquid level of the refrigerant has reached a predetermined level. And a first timer means 9 for measuring the duration of the state in which the liquid level is below a predetermined level based on the detection signal of the liquid level sensor 5, and the measurement time of the first timer means 9 is the first set time. When the above is reached, the operation signal generating means 6 for starting the operation of the refrigerant supply means 3 and the duration of the state in which the liquid level is above a predetermined level based on the detection signal of the liquid level sensor 5 Second timer means 10 for measuring, stop signal generating means 7 for stopping the refrigerant supply means 3 when the measurement time of the second timer means 10 becomes a second set time or more, and detection of the temperature sensor 4 Based on the temperature, the first set time variable setting means 8A for variably setting the first set time so as to be relatively short at low temperature and relatively long at high temperature, and the temperature detected by the temperature sensor 4. Based on the above, second setting time variable setting means 8B for variably setting the second setting time so that it is relatively short when the temperature is low and relatively long when the temperature is high.

Action When the temperature of the liquid-phase refrigerant in the lower part of the condenser 2 is low immediately after starting or during cold operation, the hysteresis, that is, the first set time and the second set time are set relatively short. Therefore, the liquid phase refrigerant is supplied to the water jacket 1 little by little, and the hunting of the refrigerant temperature in the water jacket 1 becomes very small. Further, when the refrigerant temperature in the condenser 2 is high so that hunting of the refrigerant temperature in the water jacket does not pose a problem, the first set time and the second set time are set to be relatively long. Therefore,
In this case, the frequency of operation of the refrigerant supply means 3 including a refrigerant supply pump and a solenoid valve decreases.

Embodiment FIG. 2 shows an embodiment of the boiling cooling apparatus according to the present invention, in which 11 is an internal combustion engine equipped with a water jacket 12, and 13 is a condenser for condensing a vapor phase refrigerant. , 14 are electric refrigerant supply pumps as the refrigerant supply means, respectively.

The water jacket 12 is a cylinder block 15 so as to surround the cylinder of the internal combustion engine 11 and the outer peripheral portion of the combustion chamber.
It is formed over both of the cylinder head 16 and the cylinder head 16, and the upper part, which is usually the vapor phase space, communicates with each other in each cylinder, and the steam outlet 17 is provided at an appropriate position on the upper part. The vapor outlet 17 is connected to the upper inlet 13a of the condenser 13 via a connecting pipe 18 and a vapor passage 19, and the connecting pipe 18 has a cap 20 for injecting a refrigerant.
Is provided. Further, at a predetermined level of the water jacket 12, specifically, at a substantially intermediate height position on the cylinder head 16 side, an ON / OFF signal is generated depending on the presence or absence of the liquid phase refrigerant, for example, a float type liquid using a reed switch. Surface sensor
21 is provided, and a first temperature sensor 22 including a thermistor or the like is provided below it, that is, at a position where it is submerged in the normal liquid phase refrigerant.

In addition, 23 is a heater passage 24 in the water jacket 12.
Is a heater core for heating the passenger compartment 25 connected via
A heater pump 26 that operates in conjunction with a heater switch (not shown) is provided on the downstream side thereof.

The condenser 13 is an upper tank 27 having the inlet 13a.
And a core portion 28 mainly composed of a fine tube along the vertical direction, and a lower tank 29 for temporarily storing the liquid-phase refrigerant condensed in the core portion 28. It is installed at a position where it can receive traveling wind, and an electric cooling fan 30 for forced cooling is additionally provided on the front or back of the device. In addition, the lower tank 29 is provided with a second thermistor or the like for detecting the temperature of the refrigerant therein.
A temperature sensor 31 is provided.

Reference numeral 32 denotes a reservoir tank having a volume substantially equal to the internal volume of the condenser 13, the upper space of which is open to the atmosphere via the atmosphere communication passage 33 and the lower tank via the first refrigerant circulation passage 34. It is connected to the water jacket 12 through a second refrigerant circulation passage 35 which is connected to 29 and in which the refrigerant supply pump 14 is interposed. Reference numeral 36 is a check valve that blocks the reverse flow of the refrigerant from the water jacket 12 to the reservoir tank 32. A normally open solenoid valve 37 is provided in the atmosphere communication passage 33.

Reference numeral 38 denotes a control device for controlling the refrigerant supply pump 14, the solenoid valve 37 and the like, which is a so-called micro computer system and performs a series of controls according to a predetermined program as described later.

Next, FIGS. 3 and 4 are flow charts showing the contents of the control executed by the control device 38.
The operation of the boiling cooling device configured as described above will be described with reference to this flow chart.

First, when the engine is stopped, the water jacket 12
The liquid-phase refrigerant (for example, an ethylene glycol aqueous solution) occupies the vicinity of the set level of the liquid level sensor 21, and air flows into the upper part thereof. Also, the condenser 13 is almost entirely filled with the liquid-phase refrigerant, and the reservoir tank 32 is empty.

When the engine is started in this state, the refrigerant in the water jacket 12 has a small amount of refrigerant and is in a stagnant state, and since the upper part is thermally insulated by air, the temperature immediately rises, and boiling starts soon. Here, the cooling fan 30 does not operate until the refrigerant temperature TE in the water jacket 12 reaches 85 ° C. (steps 12 and 13).

When boiling starts, the liquid-phase refrigerant in the condenser 13 is gradually discharged to the reservoir tank 32 due to the vapor pressure, and the vapor-phase refrigerant region expands to the upper part. At this time, the water jacket 12
The air remaining inside is gathered below the condenser 13 by being pushed by the vapor flow, and is naturally pushed out to the reservoir tank 32 through the first refrigerant circulation passage 34. The solenoid valve 37 is normally open and the reservoir tank 32 is open to the atmosphere. And by boiling, water jacket
When the liquid level of the refrigerant in 12 drops below the set level of the liquid level sensor 21, the liquid level control of steps 1 to 11 causes the refrigerant supply pump 14 to operate intermittently, and the reservoir tank 32 to the water tank. Refill the kettle 12 with liquid refrigerant. As a result, the liquid level of the refrigerant in the water jacket 2 is kept substantially constant until the engine is stopped. Specifically, in the refrigerant supply pump 14, the OFF signal of the liquid level sensor 21 indicates the first set time T1.
When the above continues, the operation is started (steps 5 to 8), and when the ON signal of the liquid level sensor 21 continues for the second set time T2 or more, it stops (steps 5, 9 to 11). And the first
The set time T1 and the second set time T2 are the second temperature sensor 31
If the refrigerant temperature TC in the lower tank 29 detected by is less than 5 ° C, the refrigerant temperature TC is 5 to 30 seconds in 0.1 seconds and 0.6 seconds, respectively.
If it is ℃, it will be 0.6 seconds and 2.0 seconds respectively, and the refrigerant temperature
If TC is 30 ° C or higher, 1.0 second and 2.5 seconds are set respectively (steps 1 to 4). That is, when the refrigerant temperature TC in the lower tank 29 is low, the hysteresis becomes small, and the refrigerant is supplied little by little. Therefore, the hunting of the refrigerant temperature in the water jacket 12 is prevented,
The temperature of the refrigerant supplied to the heater core 23 is also very stable. Further, when the refrigerant temperature TC in the lower tank 29 is sufficiently high, a large amount of hysteresis is provided, and the frequency of operation of the refrigerant supply pump 14 is reduced. Therefore, abrasion of the brush in the drive motor of the coolant supply pump 14 is suppressed, and durability is improved. In this embodiment, the first set time T1
Further, the second set time T2 is switched in three stages according to the refrigerant temperature TC, but it goes without saying that it can be switched more finely or can be changed continuously.

On the other hand, since the heat radiation capacity of the condenser 13 increases as the vapor phase refrigerant region expands above the condenser 13, the liquid surface position of the condenser 13 is determined at a position where this heat radiation capacity and the engine heat generation amount are in equilibrium. In other words, the liquid surface position of the condenser 13 naturally moves up and down in accordance with the load of the engine, the vehicle traveling wind, etc., while keeping the engine temperature substantially constant. The water jacket 12
Since the internal pressure of the above is maintained at about atmospheric pressure via the reservoir tank 32, the engine temperature is approximately the boiling point of the refrigerant under atmospheric pressure. Then, when the liquid level of the condenser 13 is considerably lowered and the degree of supercooling is reduced when the load is high, specifically, the refrigerant temperature TE in the water jacket 12 and the lower tank
When the temperature difference (TE−TC) from the refrigerant temperature TC in 29 becomes 10 ° C. or less, the cooling fan 30 starts to operate, and the condenser 13 is forcibly cooled (steps 14 and 19). The operation of this cooling fan 30 is
It stops when the temperature difference (TE-TC) expands to 15 ° C (steps 14 and 20).

In this way, normally, cooling using boiling and condensation of the refrigerant is performed with the solenoid valve 37 open. The flag in the flow chart corresponds to the open / closed state of the solenoid valve 37,
"0" indicates "open" and "1" indicates "closed".

When the heat radiation capacity of the condenser 13 falls below the heat generation amount of the engine for some reason, the liquid level of the refrigerant in the condenser 13 is lowered to the maximum and the degree of supercooling in the condenser 13 is reduced. In this case, when the detected temperature difference (TE-TC) becomes 5 ° C. or less, the solenoid valve 37 is closed and the reservoir tank 32 is sealed (steps 14 and 17). As a result, the pressure inside the condenser 13 and the like rises, causing the boiling point of the refrigerant to rise, so that the temperature of the refrigerant vapor flowing into the condenser 13 rises and the heat dissipation capacity of the condenser 13 increases. As a result,
When the engine temperature slightly rises, the heat radiation capacity of the condenser 13 and the engine heat generation amount rebalance, and the ejection of the refrigerant vapor or the excessive rise of the engine temperature is surely avoided.

Further, when the solenoid valve 37 is once closed as described above, the temperature TE0 of the refrigerant in the water jacket 12 at the moment of closing is stored (step 18), and the water jacket 12 may be changed due to changes in operating conditions. Refrigerant temperature TE inside is 3 ℃
The solenoid valve 37 is returned to the open state when it becomes low. For some reason, the water jacket
The solenoid valve 37 is also opened (steps 22 to 25) even when the refrigerant temperature TE in 12 rises excessively (for example, 120 ° C.).

Next, when the engine is stopped, the control of the coolant liquid level (steps 37 to 43) and the control of the cooling fan 30 (steps 35 and 36) are continued in accordance with the flow chart of FIG. 4 which is interrupted at regular intervals. As a result, jetting of refrigerant vapor and local overheating after the engine is stopped are prevented. Here, the ON / OFF hysteresis of the refrigerant supply pump 14 is fixedly given. During this time, the solenoid valve 37 is closed to secure the vapor phase refrigerant region of the condenser 13 (step 34). Further, when the temperature difference (TE-TC) is 10 to 20 ° C., the refrigerant liquid level in the condenser 13 is high and the forced cooling by the cooling fan 30 is not effective. The low temperature liquid phase refrigerant on the side of the reservoir tank 32 is mixed into the water jacket 12 and the vapor phase refrigerant area of the condenser 13 is expanded (steps 44, 4).
Five).

Then, finally, the power is turned off (step 46) and the series of control is ended. Since the solenoid valve 37 is opened by turning off the power, the liquid-phase refrigerant in the reservoir tank 32 moves into the condenser 13 as the temperature inside the water jacket 12 drops, and air is sucked in. Being filled the upper part of the water jacket 12.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications can be made. For example, in the above embodiment, the liquid-phase refrigerant condensed in the condenser 13 is supplied to the water jacket 12 via the reservoir tank 32, but the reservoir tank 32 is independent,
The water tank 12 may be supplied directly from the lower tank 29. It is also possible to use a mechanical pump that is constantly driven by the engine output as the refrigerant supply pump and control the refrigerant supply by an electromagnetic valve.

Effects of the Invention As is apparent from the above description, in the boiling cooling apparatus for an internal combustion engine according to the present invention, the ON / OFF operation hysteresis of the refrigerant supply means is appropriately set according to the refrigerant temperature in the lower part of the condenser. It is possible to prevent hunting of the refrigerant temperature in the water jacket in winter etc., to stabilize the heater outlet temperature, and to reduce the operating frequency of the refrigerant supply means such as the refrigerant supply pump.
It is possible to improve the durability of the coolant supply pump and the like.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the structure of the present invention, FIG. 2 is a structural explanatory view showing one embodiment of a boiling cooling apparatus for an internal combustion engine according to the present invention, and FIGS. 3 and 4 show this embodiment. It is a flow chart showing the contents of control. 1 ... Water jacket, 2 ... Capacitor, 3 ...
Refrigerant supply means, 4 ... Temperature sensor, 5 ... Liquid level sensor,
6 ... Actuating signal generating means, 7 ... Stop signal generating means, 8
...... Hysteresis setting means.

Claims (1)

[Claims] 1. A water jacket having a vapor outlet in the upper part and having a liquid phase refrigerant stored therein, and a liquid phase refrigerant into which a refrigerant vapor generated in the water jacket is introduced and condensed in the lower part. A condenser to be collected, a refrigerant supply means for replenishing the liquid-phase refrigerant condensed by the condenser to the water jacket, a temperature sensor for detecting the liquid-phase refrigerant temperature at the lower portion of the condenser, and a water-cooler provided in the water jacket. , A liquid level sensor for detecting whether or not the liquid level of the refrigerant has reached a predetermined level, and a first timer for measuring the duration of the state in which the liquid level is below the predetermined level based on the detection signal of this liquid level sensor Means, operation signal generation means for starting operation of the refrigerant supply means when the time measured by the first timer means is equal to or longer than the first set time, and the detection signal of the liquid level sensor. A second timer means for measuring the duration of the state that is the predetermined level or higher based liquid level in,
Based on the stop signal generating means for stopping the refrigerant supply means when the measured time of the second timer means becomes equal to or longer than the second set time and the temperature detected by the temperature sensor, the first
First setting time variable setting means for variably setting the setting time so as to be relatively short at low temperature and relatively long at high temperature, and the second setting time based on the temperature detected by the temperature sensor, A boiling cooling apparatus for an internal combustion engine, comprising: a second setting time variable setting means for variably setting a relatively short time at a low temperature and a relatively long time at a high temperature.