JPH11132041A - Water cooling type cooling device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the pressure of a cooling system even in the case of using in such a condition that causes the pressure of the cooling system to be lower than a normal value. SOLUTION: This cooling device is provided with variable throttle valves 32, 33, which are capable of being changed according to a parameter indicating a running condition, at an upstream side cooling water passage 29 and a downstream side cooling water passage 31 for connecting a reservoir tank 27 and a water pump 14. The parameter indicating a running condition includes cooling water temperature and cooling water pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-cooled cooling device for an internal combustion engine.

[0002]

2. Description of the Related Art As a cooling system for an internal combustion engine, there is known a completely closed type cooling device in which the inside of the system is completely sealed and pressure is applied. By making it a closed type, the cooling water flowing through the cooling system does not come into direct contact with the atmosphere, making it difficult to evaporate the cooling water, applying pressure to hold down the cooling water, and thereby increasing the boiling point of the cooling water Evaporation of cooling water is further prevented.

[0003] In such a cooling system of an internal combustion engine employing the completely closed pressure type cooling, the pressure of the cooling system raises the boiling point of the cooling water, so that it becomes difficult to boil.
Air bubbles are less likely to be generated in the cooling water. For this reason, contact between the cooling water and the cooling system is hardly hindered by the bubbles. Further, a large temperature difference between the cooling water and the atmosphere can be obtained.
For these reasons, the cooling efficiency is also good.

[0004] However, even in an internal combustion engine employing such closed pressurized cooling, the cooling water expands in a high temperature portion of the engine such as a cylinder, so that the pressure in the cooling system becomes high.
Therefore, it is necessary to provide the cooling system with structural strength capable of withstanding the high pressure, but this is limited.

Therefore, there is a technique for controlling the pressure in the cooling system to prevent a high pressure from being generated in the cooling system.
For example, it is disclosed in Japanese Utility Model Publication No. 7-16024. In this technology, when the pressure of the cooling water becomes too high, the pressure in the reservoir tank is released to the outside by operating the pressure cap provided in the reservoir tank, thereby reducing the pressure of the cooling system. is there.

[0006]

SUMMARY OF THE INVENTION
When the cooling water pressure rises due to overheating or the like, the air in the reservoir tank is released to the outside, thereby reducing the pressure in the reservoir tank and, consequently, the entire cooling system. Therefore, when the overheating phenomenon is eliminated, the operating state becomes a normal state, and even when the temperature of the entire cooling system changes from a high temperature state due to the overheating phenomenon to a lower temperature state, even if the temperature in the reservoir tank is high, Since the air has escaped to the outside, the pressure of the cooling water of the entire cooling system is reduced below the originally required predetermined pressure.

On the other hand, the water pump of the cooling water circulating device is usually driven by an internal combustion engine, and the pump rotation speed is usually constant as long as the rotation speed of the engine does not change. When lowered, the flowing cooling water may not be able to keep up with the rotation of the impeller. As described above, when the relative velocity between the liquid (cooling water) and the object (wall surface or impeller) increases and the local static pressure in the liquid (cooling water) decreases, so-called cavitation occurs in the region. Here, a cavity is created around the impeller, where pressure is reduced and bubbles are produced.

In this case, the cooling water does not come into direct contact with the cooling system due to the bubbles, so that the cooling efficiency of the cooling water is reduced. In addition, vibration and noise sometimes occur, and the impeller blade surfaces and wall surfaces may be damaged to shorten the service life.

In the conventional apparatus, when the pressure of the cooling system becomes higher than a normal value due to overheating or the like, as described above, the air in the reservoir tank is released to the outside. Thus, the increase in pressure can be controlled, but if the pressure of the cooling system is lower than the normal value from the beginning, there is no means for increasing the pressure, and there is no way to control this.

Further, in an internal combustion engine employing completely closed pressurized cooling, each component is designed to withstand pressure so as to withstand pressurization. The withstand pressure performance is based on the difference between the internal pressure of the cooling system and the external pressure. It is set in consideration of pressure. Therefore, when the internal combustion engine is used as an aircraft engine, during a flight, since the external pressure is lower than that on the ground, the differential pressure between the internal pressure and the external pressure of the cooling system becomes large, and the use on the ground is difficult. The pressure resistance performance assumed is insufficient. To cope with this problem, it is necessary to improve the pressure resistance of each component of the cooling system, but it is practically impossible from the economical point of view.

Therefore, when used for aircraft, the pressure applied to the cooling system must be set low from the beginning so that the pressure difference from the outside air pressure at high altitude does not become large. It is easy to occur.

The present invention has been made in view of such circumstances, and can control the level of the pressure of the entire cooling system even under a situation where the pressure of the cooling system becomes lower than a normal value. Therefore, it is an object of the present invention to provide a water-cooled cooling device for an internal combustion engine that can control the boiling point of cooling water and can further suppress the occurrence of cavitation.

[0013]

In order to solve the above-mentioned problems, a water-cooling type cooling apparatus for an internal combustion engine according to the present invention comprises a cooling water passage connecting a water jacket of an internal combustion engine body and a radiator. A water-cooled cooling system for an internal combustion engine employing a completely closed pressurized cooling system in which cooling water circulates between the radiator and the radiator in a completely sealed state and under pressure is configured as follows.

That is, a water-cooled cooling device for an internal combustion engine according to the present invention comprises a water pump serving as a starting point for circulating the cooling water, and cooling water from the cooling water passage accompanying an increase in pressure in the cooling water passage. A reservoir tank for collecting and returning the collected cooling water to the cooling water passage with a decrease in the pressure, and a cooling water passage connecting the reservoir tank and the water pump. An upstream reservoir tank passage located upstream, a downstream reservoir tank passage located downstream of the reservoir tank, and at least one of the upstream reservoir tank passage and the downstream reservoir tank passage The one reservoir tank passage is provided in a tank passage, and is provided in accordance with a parameter indicating an operation state of the cooling device. Characterized by comprising a flow path resistance varying means for varying the flow resistance, the in.

In the completely closed pressure cooling, the average pressure of each part of the cooling system is always constant if various operating conditions such as temperature are constant. Therefore, for example, if the pressure in the reservoir tank increases, the pressure in the water jacket of the internal combustion engine body decreases, whereas if the pressure in the reservoir tank decreases, the pressure in the water jacket of the internal combustion engine body increases. The pressure of each part is in a seesaw relationship with each other, if viewed relatively, because it is a completely hermetic type, as in the case of becoming high.

Accordingly, the flow path resistance of at least one of the upstream reservoir tank path and the downstream reservoir tank path can be changed by the flow path resistance varying means according to the present invention. For example, in the case where the flow path resistance variable means is provided in the upstream reservoir tank passage, if the flow path resistance is reduced, the pressure in the reservoir tank increases, while the cooling water passage, the water jacket, and the water pump Etc., the pressure of other parts becomes small. When the flow path resistance of the upstream reservoir tank passage is increased, the pressure in the reservoir tank is reduced, while the pressure in other parts such as the cooling water passage, the water jacket, and the vicinity of the water pump is increased.

On the other hand, when the flow path resistance variable means is provided in the downstream reservoir tank passage, if the flow path resistance is reduced, the pressure in the reservoir tank is reduced, while the cooling water passage, the water jacket, The pressure in other parts, such as around the water pump, increases. Further, when the flow path resistance of the downstream reservoir tank passage is increased, the pressure in the reservoir tank is increased, while the cooling water passage,
The pressure in other parts such as around the water jacket and the water pump is reduced.

If the flow path resistance of the upstream reservoir tank path is reduced in a state where the flow path resistance variable means is provided in both the upstream reservoir tank path and the downstream reservoir tank path, the downstream reservoir tank path may be reduced. When the flow path resistance of the upstream reservoir tank passage is increased, and conversely, the flow path resistance of the downstream reservoir tank passage is reduced. By doing so, the variable width of the flow path resistance is doubled as compared with the case where the flow path resistance variable means is provided in one of the reservoir tank passages.
The pressure control width in the system can be increased.

As described above, by changing the flow path resistance provided in at least one of the upstream reservoir tank passage and the downstream reservoir tank passage bordering on the reservoir tank as required, the cooling system Can be adjusted, so that the pressure of the cooling system can be reduced without opening the pressure cap of the reservoir tank as before. Therefore, control of the boiling point of the cooling water is also facilitated.

Further, even if the overheating phenomenon is eliminated, for example, the operating state becomes a normal state, and even if the temperature of the entire cooling system changes from a high temperature state caused by the overheating phenomenon to a lower temperature state, the cooling of the entire cooling system is performed. The water pressure does not drop below a predetermined pressure originally required by the cooling system.

Further, since the pressure of the entire cooling system can be controlled without releasing the air in the reservoir tank to the outside, the internal combustion engine can be sufficiently used as an aircraft engine. On the other hand, it is desirable that the channel resistance variable means can be changed in accordance with a parameter indicating the operating state, for example, the temperature and / or pressure of the cooling water.

A water pump side end of the upstream reservoir tank passage is connected to a cooling water outlet closest to the water pump among cooling water outlets for discharging the cooling water to the outside of the internal combustion engine body. A water pump side end of the downstream reservoir tank passage is connected to a cooling water inlet located closest to the water pump among cooling water inlets for introducing the cooling water from outside to inside of the internal combustion engine body. You may. By doing so, the maximum value of the pressure taken into the reservoir tank can be increased, and the pressure of the cooling water discharged from the reservoir tank can be minimized. Therefore, the width of pressure control in the cooling system can be increased, and controllability can be improved.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. <First Embodiment> A first embodiment of a water-cooled cooling device for an internal combustion engine according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, a water-cooled cooling device 1 for an internal combustion engine employs completely closed pressurized cooling. That is, the water jacket 5 a provided on the cylinder block 5 of the engine body 3 and the radiator 7 are connected by the cooling water passage 9, and the cooling water flows between the water jacket 5 a and the radiator 7 via the cooling water passage 9. Circulates completely sealed and under pressure.

The cooling water passage 9 has a radiator inlet passage 11 extending from the cooling water outlet 3a of the engine body 3 to the upper inlet 7a of the radiator 7, and a radiator extending from the lower outlet 7b of the radiator 7 to the cooling water inlet 3b of the engine body 3. An outlet passage 13 is provided.

A water pump 14 is disposed in the water jacket 5a. Starting from the water pump 14, the cooling water is supplied to the cooling water outlet 3a of the engine body 3, the radiator inlet passage 11, the radiator upper inlet 7a, the radiator 7, the radiator lower outlet 7b, the radiator outlet passage 13, and the cooling water inlet of the engine body 3. 3b, and reaches the water jacket 5a. Thereafter, the water pump 14 is again operated by the water pump 14.
The circulation between “a” and the radiator 7 is repeated. By the circulation of the cooling water, the cylinder block 5 including the water jacket 5a is efficiently cooled. For convenience, the water pump 14 is set to the most upstream side, and hereinafter, the upstream side means the side flowing from the water pump 14.

Although not shown, there are a plurality of outlets from the water jacket 5a to the outside. Of these outlets, the cooling water outlet 3a toward the radiator 7 is located closest to the water pump 14. Similarly, there are a plurality of inlets from the outside to the water jacket 5a. Of these inlets, the cooling water inlet 3b from the radiator 7 to the water jacket 5a is located closest to the water pump 14.

A thermostat 17 is arranged in the radiator outlet passage 13. This thermostat 1
The cooling water 7 is not required to be cooled by the radiator 7 when the cooling water is not cooled by the radiator 7 and the temperature is low, so the radiator outlet passage 13 is shut off and the cooling water flows to the radiator 7. This is to temporarily stop the flow so that it does not occur. Therefore, while the thermostat 17 is functioning, the cooling water circulates in the water jacket 5a without passing through the radiator 7.

Further, the in-vehicle heating heater 19 and the engine body 3 are connected via a heater cooling water introduction passage 23 and a heater cooling water discharge passage 25. Further, a reservoir tank 27 is disposed between the cooling water outlet 3a of the engine body 3 and the cooling water inlet 3b of the engine body 3, and the reservoir tank 27 is connected to the upstream reservoir tank connected to the cooling water outlet 3a. Passage 29 and cooling water inlet 3
b and is connected to the downstream reservoir tank passage 31 connected to b.

The reservoir tank 27 collects the cooling water from the cooling water passage 9 as the pressure in the cooling water passage 9 rises, and removes the cooling water already collected as the pressure decreases. Return to 9. The reservoir tank 27 has a cooling water supply port, and the cooling water supply port is closed by a pressure cap 27a.

By interposing the upstream reservoir tank passage 29 and the downstream reservoir tank passage 31, cooling water is circulated between the reservoir tank 27 and the water pump 14.

The upstream reservoir tank passage 29 and the downstream reservoir tank passage 31 are respectively provided with variable throttle valves 32 and 33 as passage resistance variable means at substantially the centers thereof.

Variable throttle valve 32 and variable throttle valve 33
Is used to change the flow path resistance in the upstream reservoir tank passage 29 and the downstream reservoir tank passage 31, respectively, and electronically controls the actuator 34 in accordance with a parameter indicating the operating state of the water-cooled cooling device 1 for the internal combustion engine. Thus, the opening degree is controlled.

When the opening of these valves 32 and 33 increases, the flow resistance decreases, and when the opening decreases, the flow resistance increases. The parameters indicating the operation state of the cooling device include the cooling water pressure and the cooling water temperature at the cooling water inlet 3b where cavitation may occur. However, cavitation occurs due to low pressure.

The cooling water temperature (T _{W / P-IN} ) and the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3 b are respectively measured by a temperature sensor 35 and a pressure sensor 36 provided at the cooling water inlet 3 b. Is detected.

The parameters detected by the temperature sensor 35 and the pressure sensor 36 are input to the CPU 37. Further, the CPU 37 is electrically connected to the actuator 34 and operates in a state where the actuator 34 is controlled in accordance with the parameters input to the CPU 37, whereby the required amount of the variable throttle valves 32, 33 is opened or closed. Close or adjust the opening.

FIG. 2 shows the opening control of the variable throttle valves 32 and 33.
FIG. 3 is a functional block diagram for controlling
(Pump inlet) pressure at the cooling water inlet 3b as shown in FIG.
Read-out pre-stored function map M of force and cooling water temperature
Dedicated memory R is connected. Also, the CPU 37
The parameters detected from the temperature sensor 35 and the pressure sensor 36
The cooling water pressure at the cooling water inlet 3b (P
_{W / P-IN}) And cooling water temperature (T _{W / P-IN}) Against the above map
To determine the limit of cavitation
Actuating means based on the determination result of
The control means C for driving and controlling the eta 34 is functionally realized.
Have been. These function realizing means
Run the program stored in the dedicated memory R on the CPU.
It is realized by having

A solid line diagram in FIG. 3 shows a control target value of the cooling water pressure at the cooling water inlet 3b, which is indicated by a reference symbol P _{(T) W / P-IN} . The diagram shown by the broken line is the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b.
FIG. 5 is a diagram in which the maximum values of the pressures within the allowable range, which may be higher than the control target value P _{(T) W / P-IN} , are continuously connected. Then, the cooling water pressure (P
_{W / P-IN)} is indicated by the control target value of the cooling water pressure _{(P (T) W / P} -IN) codes the absolute value of the good pressure difference even higher than P _(A).

The dashed-dotted line diagram shows that the cooling water pressure (P _{W / P- IN} ) at the cooling water inlet 3b is equal to the control target value P _{(T) W / P} of the cooling water pressure at the cooling water inlet 3b. FIG. 9 is a diagram in which minimum values of pressure in a range in which the pressure may be lower than _-IN are continuously connected. The cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b is equal to the cooling water pressure control target value (P
The absolute value of the pressure difference that may be lower than _{(T) W / P-IN} ) is indicated by a symbol P _(B) .

The map shown in FIG. 3 shows the cooling water inlet 3b.
Indicates that cavitation occurs when the cooling water pressure is lower than the alternate long and short dash line. In addition, when viewing this map, it is assumed that the engine speed is constant.

Next, a control routine for driving and controlling the variable throttle valves 32 and 33 will be described with reference to the flowchart of FIG. First, in step 1, the engine body 3 is started. Note that steps will be simply indicated by “S” below. Next, in S2, the determination means I determines the control target value P of the cooling water pressure at the cooling water inlet 3b from the cooling water temperature (T _{W / P-IN} ) at the cooling water inlet 3b.
_{(T) W / P-IN} and absolute values P _(A) and P _(B) of the pressure difference are obtained from the map of FIG.

Further, in S3, the judgment means I determines the control target value (P _{(T) W / P)} of the cooling water pressure at the cooling water inlet 3b from the cooling water pressure (P _{W / P- IN} ) at the cooling water inlet 3b. _-IN )
Calculate the differential pressure value (P _(d) ) by subtracting.

In S4, the judgment means I determines the differential pressure value (P
_(d) ) is determined to be equal to or smaller than the absolute value of the pressure difference (P _(A) ). When the determination is negative, the process proceeds to S5, and when the determination is affirmative, the process proceeds to S6.

In S5, at least one of the opening direction control of the variable throttle valve 32 and the closing direction control of the variable throttle valve 33 is performed by the control signal from the control means C, and thereafter, the process returns to S2. By performing at least one of the opening direction control of the variable throttle valve 32 and the closing direction control of the variable throttle valve 33, the opening degree of the variable throttle valve 32 is relatively higher than that of the variable throttle valve 33. For this reason, the pressure of the reservoir tank 27 increases, and on the other hand, the cooling water passage 9,
Water jacket 5a, around water pump 14, etc.
The pressure in other parts is reduced.

In S6, the judgment means I determines the differential pressure value (P
_(d) ) is determined to be equal to or greater than the absolute value of the pressure difference (P _(B) ). In the case of a negative determination, the process proceeds to S7, and in the case of an affirmative determination, the process proceeds to S2.

In S7, at least one of the closing direction control of the variable throttle valve 32 and the opening direction control of the variable throttle valve 33 is performed by the control signal from the control means C, and thereafter, the process returns to S2. By performing at least one of the closing direction control of the variable throttle valve 32 and the opening direction control of the variable throttle valve 33, the opening degree of the variable throttle valve 32 is relatively lower than that of the variable throttle valve 33. For this reason, the pressure in the reservoir tank 27 decreases, while the pressure in other parts such as the cooling water passage 9, the water jacket 5a, the water pump 14 and the like increases.

In controlling the opening and closing of the variable throttle valve 32 and the variable throttle valve 33, the following may be considered. (1) The opening (or closing) degree is controlled in the minimum unit at a time, and feedback is repeated until an appropriate control pressure value is obtained. (2) The cooling water temperature (T _{W / P-IN} ) at the cooling water inlet 3 b, the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3 b, and the control target value of the cooling water pressure at the cooling water inlet 3 b From the differential pressure value (P _(d) ) with (P _{(T) W / P-IN} ),
A function map (not shown) in which the opening and closing amounts of the variable throttle valve 32 and the variable throttle valve 33 are determined is prepared, and the
37, and are stored in the read-only memory R. Then, the valve is opened and closed according to the map value. <Operation and Effect of First Embodiment> Next, the operation and effect of the water-cooled cooling device 1 for an internal combustion engine having such a configuration will be described.

In the water-cooled cooling system 1 for an internal combustion engine, the upstream reservoir tank passage 29 bordering on the reservoir tank 27
Throttle valve 3 and the downstream reservoir tank passage 31
2, 33 are provided. The opening and closing of these variable throttle valves 32 and 33 are controlled by the pressure at the cooling water inlet 3b and the cooling water temperature as parameters indicating the operating state of the cooling device. Therefore, the flow path resistance in the upstream reservoir tank passage 29 and the downstream reservoir tank passage 31 changes according to the opening / closing state of the variable throttle valves 32 and 33. As a result, the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b and the cooling water temperature (T
_{W / P-IN} ), the pressure in the reservoir tank 27 increases, but the cooling water passage 9, the cooling water inlet 3b, and the cooling water outlet 3
a, water jacket 5a, around water pump 14, etc., while the pressure in other parts decreases, and conversely, the pressure in reservoir tank 27 decreases, but cooling water passage 9, water jacket 5a, cooling water inlet 3b, cooling water Exit 3a,
The pressure of other parts, such as around the water pump 14, may increase.

More specifically, the CPU 37 calculates the control target value (P _{(T) W / P-IN} ) of the cooling water pressure at the cooling water inlet 3b from the cooling water pressure (P _{W / P- IN} ) at the cooling water inlet 3b.
The differential pressure value (P _(d) ) obtained by subtracting is the absolute value of the pressure difference (P _(A) )
If it is determined that the flow rate is larger than the predetermined value, the CPU 37 controls the variable throttle valve 32 of the upstream reservoir tank passage 29 to open so as to reduce the flow path resistance of the upstream reservoir tank passage 29. Further, control is performed such that the variable throttle valve 33 of the downstream reservoir tank passage 31 is throttled to increase the flow path resistance of the downstream reservoir tank passage 31.

By doing so, the reservoir tank 2
The internal pressure of 7 rises. On the other hand, reservoir tank 2
7, the internal pressures of the water jacket 5a, the radiator 7, the cooling water passage 9, the cooling water inlet 3b, the cooling water outlet 3a, and the like relatively decrease.

When the differential pressure value (P _(d) ) is smaller than the absolute value (P _(B) ) of the pressure difference, the variable throttle valve 32 of the upstream reservoir tank passage 29 is throttled to reduce the upstream pressure. The flow path resistance in the reservoir tank passage 29 is increased. Also, the variable throttle valve 33 of the downstream reservoir tank passage 31 is opened to reduce the flow path resistance in the downstream reservoir tank passage 31.

By doing so, the reservoir tank 2
The internal pressure of 7 falls. On the other hand, reservoir tank 2
7, the internal pressures of the water jacket 5a, the radiator 7, the cooling water passage 9, the cooling water inlet 3b, the cooling water outlet 3a, etc. rise relatively.

As described above, the level of the pressure of the cooling system can be adjusted by opening and closing the variable throttle valves 32 and 33 as necessary, so that the pressure cap of the reservoir tank does not need to be opened as in the related art. , Reservoir tank 2
7, the pressure of the cooling system other than the upstream reservoir tank passage 29 and the downstream reservoir tank passage 31 can be controlled to be reduced.

FIG. 5 graphically shows these relationships. In FIG. 5, a solid line indicates a case where the variable throttle valve 32 is closed as compared with the variable throttle valve 33, and a broken line indicates a case where the variable throttle valve 33 is closed as compared with the variable throttle valve 32. As a comparative example, a case where the valve openings of the variable throttle valve 32 and the variable throttle valve 33 are the same is indicated by a chain line.

As shown in FIG. 5, when the variable throttle valve 32 is closed as compared with the variable throttle valve 33, the pressure of the reservoir tank 27 decreases, but the cooling water passage 9, the cooling water inlet 3b, the cooling water outlet 3a, and the water jacket 5a. , Water pump 1
It can be seen that the pressure in other parts other than the reservoir tank 27, such as around four, becomes high. Conversely, when the variable throttle valve 33 is closed compared to the variable throttle valve 32, the pressure of the reservoir tank 27 increases, but the cooling water passage 9, the cooling water inlet 3b,
It can be seen that the pressure of other parts other than the reservoir tank 27, such as the cooling water outlet 3a, the water jacket 5a, the water pump 14, and the like, becomes low. In addition, the variable throttle valve 32
It can be seen that when the valve opening of the variable throttle valve 33 is the same, that is, in the case of the alternate long and short dash line, it is always located between the solid line and the broken line.

Accordingly, even if the pressure of the cooling system is considerably increased to the extent that overheating occurs with the conventional techniques, the variable throttle valve 32 of the upstream reservoir tank passage is opened and the downstream reservoir tank passage is opened. If the internal pressure of the reservoir tank 27 is increased by closing the variable throttle valve 33 of the reservoir 31, the reservoir tank 27, the upstream reservoir tank passage 29, and the downstream reservoir tank passage 31
The pressure of the cooling system other than the above can be reduced and controlled. Therefore, even if the high-pressure state is eliminated and the operating state becomes a normal state, and the temperature of the entire cooling system changes from the above-described high-temperature state due to the overheating phenomenon to a lower temperature state, the cooling system is originally required. Predetermined pressure can be maintained. As a result, the cavitation can be suppressed without lowering the boiling point of the cooling water.

Assuming that the cooling water temperature is constant, as can be seen from FIG. 6, the engine speed (N
e), the lower the cooling water pressure (P
_{W / P-IN} ) increases, and the cooling water pressure (P
_E-OUT ) is lower, so if the engine is adapted at the maximum engine speed, a lower engine speed (N
In e), no cavitation occurs.

Also, since the level of the pressure of the entire cooling system can be controlled, even when the internal combustion engine is used in a place where the pressure of each part of the cooling system becomes lower than a normal value and the pressure is low,
For example, even when the internal combustion engine is used as an aircraft engine, it can sufficiently cope without having to increase the structural strength of the internal combustion engine.

FIG. 7 shows the mechanism by which cavitation occurs in the relationship between temperature and pressure, and shows pressure changes at the cooling water outlet 3a of the engine body 3 and at the cooling water inlet 3b of the engine body 3. It is a graph.

The symbols, definitions of terms and conditions shown in FIG. 7 are as follows. a1: Cooling water pressure at cooling water outlet 3a when cooling water temperature is normal temperature (for example, 100 ° C.) a2: Cooling at cooling water inlet 3b when cooling water temperature is normal temperature (for example, 100 ° C.) Water pressure b1: If the pressure at the cooling water outlet 3a becomes higher than this, it becomes structurally unbearable. When the pressure limit is reached, the pressure cap 2 of the reservoir tank 27
Pressure at cooling water outlet 3a when opening 7a. FIG.
For example, the absolute value is 2.8 kg / cm ² .

B2: The cooling water inlet 3b when the pressure cap 27a of the reservoir tank 27 is opened when the pressure at the cooling water outlet 3a reaches the limit value.
Pressure.

C1: When the air is released into the atmosphere by opening the pressure cap 27a in order to avoid the overheating phenomenon, and thereafter, when the temperature becomes slightly higher than the normal temperature (for example, 110 ° C.). At the cooling water outlet 3a.

C2: When the air is released into the atmosphere by opening the pressure cap 27a in order to avoid the overheating phenomenon, and thereafter, when the temperature becomes slightly higher than the normal temperature (for example, 110 ° C.). At the cooling water inlet 3b.

D1: When the pressure in the reservoir tank 27 is released to the atmosphere by opening the pressure cap 27a, then the pressure and the temperature are rapidly reduced from the state of c1 and the cooling is performed when the temperature reaches the normal temperature. Water outlet 3a
Pressure.

D2: When the pressure in the reservoir tank 27 is released to the atmosphere by opening the pressure cap 27a, then the pressure and temperature are rapidly reduced from the state of c2, and the cooling is performed when the temperature reaches the normal temperature. Water inlet 3b
Cooling water pressure at

C1 ': When air is not released into the atmosphere with the pressure cap 27a closed, the cooling water pressure at the cooling water outlet 3a exceeds the limit value and becomes higher than the normal temperature (for example, 110 ° C.). At the cooling water outlet 3a when the overheating phenomenon occurs at the temperature of

C2 ': When air is not released into the atmosphere while the pressure cap 27a is closed, the cooling water pressure at the cooling water outlet 3a exceeds the limit value and becomes higher than the normal temperature (for example, 110 ° C.). At the cooling water inlet 3b when the overheating phenomenon occurs at the temperature of

P _E-OUT : cooling water pressure at the cooling water outlet 3a. P _{W / P-IN} : cooling water pressure at cooling water inlet 3b. Cavitation limit: Indicates that cavitation occurs when the pressure is below the curve L in FIG.

P _E-OUT limit: A limit value of the pressure resistance at which the structure cannot withstand the pressure at the cooling water outlet 3a when the pressure becomes higher. Condition: Constant engine speed.

In FIG. 7, the cooling water pressure (P _E-OUT ) at the cooling water outlet 3a is changed to the cooling water pressure a1 (2.55 kg / c) at the cooling water outlet 3a at a normal temperature of 100 ° C.
m ² ) from the state of the limit value b 1 (2.8 kg /
cm ² ), the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b is changed from a 2 (1.3 kg / cm ² ) to b 2
(1.55 kg / cm ² ).

Even if the reservoir tank cap 27a is opened, the cooling water outlet 3a, the cooling water inlet 3
In any case b, the cooling water pressure at b1 or b2 is maintained (see b1 → c1 and b2 → c2). Then, in this state, the cooling water temperature rises to 110 ° C., and the cooling water pressure at the cooling water outlet 3a and the cooling water inlet 3b shifts from b1 to c1 or from b2 to c2, respectively. Both at the outlet 3a and at the cooling water inlet 3b, the temperature and cooling water pressure drop sharply, shifting from c1 to d1 and from c2 to d2, respectively.

At this time, at the cooling water inlet 3b, d
2 moves below the curve L and the cooling water pressure at the cooling water inlet 3b exceeds the cavitation limit, so that cavitation occurs at the cooling water inlet 3b.

On the other hand, even in the case where the reservoir tank cap 27a needs to be opened due to an overheating phenomenon or the like, if the reservoir tank cap 27a is not opened, the pressure (P _E-OUT ) of the cooling water outlet 3a will be maintained. Is P
Since it exceeds the _E-OUT limit, it becomes structurally intolerable.

In the water-cooled cooling system 1 for an internal combustion engine, even if the pressure of the cooling system becomes so high that the reservoir tank cap 27a must be opened due to an overheating phenomenon or the like, the reservoir tank cap 27a is not opened without opening the reservoir tank cap 27a. By increasing the pressure of the reservoir tank 27,
The internal pressures of the cooling system other than the water jacket 5a, the radiator 7, and the cooling water passage 9 are reduced.

For this reason, even if the temperature of the entire cooling system changes from a high temperature state to a lower temperature state, the cooling water pressure of the entire cooling system falls below a predetermined pressure originally required by the cooling system. There is no such thing. That is, the cooling water pressure at the cooling water inlet 3b does not exceed the cavitation limit.

On the other hand, the cooling water outlet 3 a for discharging the cooling water to the outside of the engine body 3 is located closest to the water pump 14 among the cooling water outlets. The upstream end of the reservoir tank passage 29 on the water pump side is connected to the cooling water outlet 3a.

The cooling water inlet 3b for introducing cooling water from the outside to the inside of the engine body 3 is located closest to the water pump 14 among the cooling water inlets. The water pump side end of the downstream reservoir tank passage 31 is connected to the cooling water intake 3b.

For this reason, the maximum value of the pressure taken into the reservoir tank 27 can be increased, and the pressure of the cooling water discharged from the reservoir tank 27 can be minimized. Therefore, the width of the pressure control in the cooling system can be increased, and the controllability can be improved.

Further, in this embodiment, the upstream reservoir tank passage 29 and the downstream reservoir tank passage 31 are provided with the variable throttle valve 32 and the variable throttle valve 33, respectively. However, since only the flow rate of the cooling water is changed by changing the flow path resistance with respect to the other path, the variable throttle valve is provided only on one side and not provided on the other path. It can be said that they are substantially the same. Further, the flow rate in the two passages may be relatively different by increasing the diameter of the passage in which the variable throttle valve is not provided.

A cooling water passage may be provided in addition to the upstream reservoir tank passage 29 and the downstream reservoir tank passage 31. For example, between the reservoir tank 27 and other parts of the engine body 3 or the reservoir tank 27
A cooling water passage is provided between the cooling water passage and the radiator 7, and a variable throttle valve is also provided in the cooling water passage. By doing so, the route of the flow of the cooling water to the reservoir tank 27 changes, so that the distribution of the cooling water pressure can be greatly changed, and the pressure control becomes easier.

The variable throttle valves 32 and 33 are electronically controlled. Instead, a thermo valve which operates at a predetermined temperature or higher is installed, and when the cooling water reaches a predetermined temperature or higher, the variable throttle valves 32 and 33 operate. By doing so, an increase in the cooling water pressure may be prevented.

The operating order of the variable throttle valves 32 and 33 may be restricted depending on the characteristics of the engine body 3 and the arrangement of the radiator 7 and the like. For example, when the amount of cooling water flowing to the reservoir tank 27 increases, it is necessary to change the amount flowing to the radiator 7. When the cooling capacity is affected, it is necessary to operate the valve so as not to change the flow rate as much as possible. <Second Embodiment> Next, a second embodiment of a water-cooled cooling system for an internal combustion engine according to the present invention will be described with reference to FIGS.

The water-cooled cooling device 1A for an internal combustion engine according to the second embodiment is different from the water-cooled cooling device 1 for an internal combustion engine according to the first embodiment in that the pressure sensor and the water temperature sensor are mounted at different locations. Only the difference and the point related to the opening and closing of the variable throttle valve taking into account the crank angle that can be converted to the engine speed Ne and the parts related thereto are taken into account.
The same reference numerals are given to the other same parts, and the description is omitted.

As shown in FIG. 8, in the water-cooled cooling device 1A for the internal combustion engine, the temperature sensor 135 and the pressure sensor 13
Numerals 6 are arranged in the vicinity of the radiator upper inlet 7a of the radiator 7, and detect the cooling water temperature (T ₀ ) and the cooling water pressure (P ₀ ) in the vicinity of the radiator upper inlet 7a, respectively. A crank angle sensor 139 that detects a crank angle and is electrically connected to the ECU 138 is disposed near a crankshaft (not shown).

The ECU 138 is a computer control device for performing overall control of the internal combustion engine, and the CPU 37 realizes the functions shown in FIG. 2 and performs the opening of the variable throttle valves 32 and 33 as described above. It is a computer control device that performs control, and both are electrically connected.

Temperature sensor 135 and pressure sensor 136
The cooling water temperature (T ₀ ) and the cooling water pressure (P ₀ ), which are the parameters detected by the above, are input to the CPU 37. The CPU 37 is electrically connected to the actuator 34, and detects a cooling water temperature and a cooling water pressure as parameters input to the CPU 37, and a parameter detected by the crank angle sensor 139 and converted from a crank angle input to the ECU 138. Actuator 34 operates in accordance with the engine speed. Then, correspondingly, the variable throttle valves 32 and 33 are opened or closed by a required amount.

FIG. 9 is a functional block diagram for controlling the degree of opening of the variable throttle valves 32 and 33. The CPU 37 controls the pressure (cooling pump inlet) and cooling at the cooling water inlet 3b as shown in FIG. A read-only memory R in which a function map M with the water temperature is stored in advance is connected. Further, the CPU 37 supplies the coolant temperature (T ₀ ), coolant pressure (P ₀ ) and engine speed (Ne) near the radiator upper inlet 7 a detected or converted by the temperature sensor 135, the pressure sensor 136, and the crank angle sensor 139. ) Is compared with the above-described map to determine a cavitation occurrence limit, and a control unit C that controls the drive of the actuator 34 based on the determination result of the determination unit I is realized by a program.

Hereinafter, a control routine for controlling the drive of the variable throttle valves 32 and 33 will be described with reference to the flowchart of FIG. First, after the engine body 3 is started in S201, in S202, the radiator upper entrance 7 already detected by the temperature sensor 35 and inputted to the CPU 37 is inputted.
The cooling water temperature (T _{W / P-IN} ) at the cooling water inlet 3b is calculated from the cooling water temperature (T ₀ ) in the vicinity of a and the engine speed (Ne). For this calculation, the ECU 138
A map (not shown) for obtaining the cooling water temperature (T _{W / P-IN} ) stored in a read-only memory (not shown) is used.

Next, in step S203, the cooling water pressure (P ₀ ) near the radiator upper inlet 7a, which has already been detected by the pressure sensor 136 and has been input to the CPU 37, the cooling water temperature (T ₀ ) and the engine speed (Ne). From this, the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b is calculated. Even when calculating this cooling water pressure (P _{W / P-IN} ), E
A map (not shown) for obtaining the cooling water pressure (P _{W / P-IN} ) stored in a read-only memory (not shown) of the CU 138 is used.

From the cooling water temperature (T _{W / P-IN} ) and the engine speed (Ne) obtained in S 202 in S 204, the control target value P _{(T) W / P−} of the cooling water pressure at the cooling water inlet 3 b is obtained. _IN and absolute values P _(A) and P _(B) of the pressure difference are obtained from a map ₍ not shown ₎ .

Steps S205 to S209 correspond to steps S3 to S7 described in the first embodiment, respectively, and a description thereof will be omitted. <Effects of the Second Embodiment> The second embodiment has the same effects as the first embodiment, but also measures the cooling water pressure and the cooling water temperature at the cooling water inlet. It can be seen that other than 3b is also possible.

Further, the engine speed (Ne) is changed to the cooling water pressure (P _{W / P-IN} ), the control target value of the cooling water pressure at the cooling water inlet 3 b (P _{(T) W / P-IN} ), The absolute value of the pressure difference (P _(A) ) at which the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b can be higher than the above-mentioned P _{(T) W / P-IN;} The absolute value (P P) of the pressure difference (P _{W / P-IN} ) at which the cooling water pressure (P _{W / P-IN} ) at the cooling water inlet 3b may be lower than the control target value P _{(T) W / P-IN} of the cooling water pressure at the cooling water inlet 3 b. _{Since (B)} ) is taken into account, it is not necessary to increase P _(A) and P _(B) in a low engine speed (Ne) region where there is virtually no cavitation concern. It is not necessary to perform useless control.

In the second embodiment, the temperature sensor 135 and the pressure sensor 136 are shown as being disposed near the radiator upper inlet 7a of the radiator 7. However, the reservoir tank 27 and the upstream reservoir tank passage Any location other than the location closed by the 29 and the downstream reservoir tank passage 31 may be used.

[0094]

According to the water-cooled cooling system for an internal combustion engine of the present invention, the flow which is changed according to the engine operating state is changed to the upstream reservoir tank passage and the downstream reservoir tank passage connecting the reservoir tank and the water pump. By providing the road resistance variable means, it is possible to control the level of the pressure of the entire closed cooling system. As a result, even when the external pressure is low, it is possible to effectively control the occurrence of cavitation and the decrease in the boiling point of the cooling water. This is particularly effective in preventing cavitation when the internal combustion engine is used in a situation where the pressure of the cooling system becomes lower than a normal value, such as when the internal combustion engine is used as an aircraft engine.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram showing a first embodiment.

FIG. 2 is a block diagram for opening and closing a variable throttle valve.

FIG. 3 is a function map of cooling water pressure and cooling water temperature at a cooling water inlet.

FIG. 4 is a flowchart for explaining a control routine for controlling the drive of the variable throttle valve in the first embodiment.

FIG. 5 is a diagram showing a pressure distribution at each part due to a difference in throttle of the variable throttle valve.

FIG. 6 is a diagram showing a cavitation limit based on a relationship between a cooling water pressure and an engine speed.

FIG. 7 is a diagram showing a cavitation generation mechanism.

FIG. 8 is a schematic overall configuration diagram showing a second embodiment.

FIG. 9 is a block diagram for opening and closing the variable throttle valve.

FIG. 10 is a flowchart for explaining a control routine for driving and controlling the variable throttle valve in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Water-cooling type cooling device of an internal combustion engine 3 ... Engine main body (internal combustion engine main body) 3a ... Cooling water outlet of an engine main body 3b ... Cooling water inlet of an engine main body 5 ... Cylinder block 5a ... Water jacket 7 ... Radiator 7a ... Upper part of a radiator Inlet 7b: Lower outlet of radiator 9: Cooling water passage 11: Radiator inlet passage 13: Radiator outlet passage 14: Water pump 17: Thermostat 19: Heater for vehicle heating 19a: Heater inlet side for vehicle heating 19b: Heater outlet for vehicle heating Side 21: Cooling water outlet of engine body 23 ... Cooling water introduction passage for heater 25 ... Cooling water discharge passage for heater 27 ... Reservoir tank 27a ... Pressure cap 29 ... Upstream reservoir tank passage 31 ... Downstream reservoir tank passage 32 33 ... Variable throttle valve (flow path resistance variable means) 34 ... actuator 35 ... Temperature sensor 36 ... a pressure sensor 37 ... CPU P W / P- IN ... control of the cooling water pressure in the cooling water pressure _{P (T) W / P-} IN ... cooling water inlet 3b of the cooling water inlet 3b Target value P _(A) , P _(B) ... cooling water pressure (P
_{W / P-IN} ) and the absolute value of the pressure difference between the control target value of the cooling water pressure (P _{(T) W / P-IN} ) P _(d) ... the cooling water pressure at the cooling water inlet 3b (P _{W / P -IN} ) minus the differential pressure value obtained by subtracting the control target value (P _{(T) W / P-IN} ) of the cooling water pressure at the cooling water inlet 3b. Ne: engine speed P _E-OUT : cooling water at the cooling water outlet 3a. Pressure T _{W / P-IN} … Cooling water temperature at cooling water inlet 3b 1A… Water-cooled cooling device of internal combustion engine 135… Temperature sensor 136… Pressure sensor 138… ECU 139… Crank sensor T ₀ … Cooling near radiator upper inlet 7a Water temperature P ₀ ... cooling water pressure near the radiator upper inlet 7a

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F01P 7/16 501 F01P 7/16 501 11/16 11/16 Z 11/18 11/18 A

Claims (3)

[Claims] 1. A cooling water circulates between the water jacket and the radiator in a completely sealed state and under a pressure through a cooling water passage connecting the water jacket and the radiator of the internal combustion engine body. In a water-cooled cooling device for an internal combustion engine employing completely closed pressurized cooling, a water pump serving as a starting point for circulating the cooling water, and cooling water from the cooling water passage with an increase in pressure in the cooling water passage. A reservoir tank for collecting and returning the collected cooling water to the cooling water passage with the decrease in the pressure, a cooling water passage connecting the reservoir tank and the water pump, and An upstream reservoir tank passage located upstream, and a downstream reservoir tank located downstream from the reservoir tank A passage, provided in at least one of the upstream reservoir tank passage and the downstream reservoir tank passage, the passage resistance in the one reservoir tank passage according to a parameter indicating an operation state of the cooling device. A water-cooled cooling device for an internal combustion engine, comprising: a variable flow path resistance changing means. 2. The water-cooled cooling system for an internal combustion engine according to claim 1, wherein the parameter indicating the operation state is at least one of a temperature and a pressure of cooling water. 3. A water pump side end of the upstream reservoir tank passage is connected to a cooling water outlet located closest to a water pump among cooling water outlets for discharging the cooling water toward the outside of the internal combustion engine body. A water pump side end of the downstream reservoir tank passage is connected to a cooling water inlet located closest to the water pump among cooling water inlets for introducing the cooling water from outside to inside of the internal combustion engine body. The water-cooled cooling device for an internal combustion engine according to claim 1 or 2, wherein: