JPH10317961A - Cooling system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system for an internal combustion engine, capable of reducing the amount of harmful exhaust gas and improving fuel economy. SOLUTION: A first fluid circuit 12 holding therein the first refrigerant is defined between an internal combustion engine 1 and a first heat exchanger 11, and a second fluid circuit 13 holding therein the second refrigerant is defined between the first heat exchanger 11 and a second heat exchanger 2. The second heat exchanger 2 has a cooling fan 6a for heat radiation use. That constitution shortens the engine warm-up after its start-up to reduce the amount of harmful exhaust gas produced, and requires no interposition of thermostats adapted to expand or contract by heat in the fluid circuits to thus considerably reduce resistance to the refrigerants flowing in the fluid circuits. The refrigerants may be thus circulated with a battery-drive motor, which lessens the engine load and improves the fuel economy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system for use in an internal combustion engine such as an automobile engine, and more particularly, to a cooling system for an internal combustion engine capable of always maintaining the temperature of the engine in an optimum operating state. It is about.

[0002]

2. Description of the Related Art In an internal combustion engine (hereinafter referred to as an engine) used for an automobile or the like, a water-cooled cooling device using a radiator is generally used for cooling the engine. In this type of cooling device, a thermostat is used to control the temperature of the cooling water, and when the cooling water is lower than a predetermined temperature, the cooling water flows to a bypass passage by the action of the thermostat. The cooling water is circulated without passing through the radiator. FIG.
The reference numeral 1 denotes an internal combustion engine composed of a cylinder block 1a and a cylinder head 1b. The cylinder block 1a of the engine 1
Further, a fluid passage indicated by an arrow c is formed in the cylinder head 1b. Reference numeral 2 denotes a heat exchanger, that is, a radiator. The radiator 2 has a fluid passage 2c as is well known, and a cooling water inlet 2a and a cooling water outlet 2b of the radiator 2 are connected to the engine 1. It is connected to a cooling water passage 3 for circulating cooling water between them.

The cooling water passage 3 has an outlet cooling water passage 3a communicating from a cooling water outflow portion 1d provided in the upper part of the engine 1 to a cooling water inflow portion 2a provided in the upper part of the radiator 2, and a cooling water passage 3a of the radiator 2. An inflow cooling water passage 3b communicating from a cooling water outflow portion 2b provided at a lower portion to a cooling water inflow portion 1e provided at a lower portion of the engine 1, and a bypass water passage connecting midway portions of the two cooling water passages 3a, 3b. 3c. Further, a thermostat 4 is disposed at a branch portion of the cooling water channel 3 between the outflow-side cooling water channel 3a and the bypass water channel 3c. The thermostat 4 has a built-in thermal expansion body (for example, wax) that expands and contracts due to a change in cooling water temperature, and when the cooling water temperature is high (for example, 80 ° C. or higher), the thermal expansion body expands. The valve is opened to allow the cooling water flowing out of the outflow portion 1d of the engine 1 to flow into the radiator 2 through the outflow-side cooling water passage 3a, and the cooling water that has been radiated by the radiator 2 and has a low temperature flows out of the outflow portion 2b. Cooling water passage 3b
And flows into the engine 1 from the inflow portion 1e of the engine 1.

When the temperature of the cooling water is low, the valve of the thermostat 4 is closed by the contraction of the thermal expansion member, and the cooling water flowing out of the outlet 1d of the engine 1 is supplied to the bypass water passage 3d.
c, it flows from the inflow portion 1e of the engine 1 to the cooling passage c in the engine 1. Note that FIG.
In the figure, reference numeral 5 denotes a water pump disposed in the inflow portion 1e of the engine 1, which rotates a rotation shaft by rotation of a crankshaft (not shown) of the engine 1 to forcibly circulate cooling water. Reference numeral 6 denotes a fan unit for forcing cooling air into the radiator 2 and includes a cooling fan 6a and a fan motor 6b for rotating the fan.

[0005]

By the way, the valve opening and valve closing action by the thermostat as described above is determined by the temperature of the cooling water, and moreover by the expansion and contraction action by a thermal expansion body such as wax. Therefore, the temperature at the time of valve opening and the temperature at the time of valve closing are not constant,
It has a so-called hysteresis characteristic. For this,
There is a technical problem that it is extremely difficult to adjust the temperature of the cooling water of an automobile engine having a large change in the calorific value to a desired temperature. In addition, particularly in the case of an automobile engine, there are other technical problems as described below.

[0006] Hazardous exhaust gases (particularly carbon monoxide, nitrogen oxides, hydrocarbons, etc.) emitted by the operation of the engine are generated in large amounts at a relatively low temperature when the engine is started. Therefore, it is desirable that the engine be warmed up to a predetermined temperature as soon as the engine is started. However, harmful exhaust gas is generated for a long time because a large amount of cooling water slows down the promotion of the warming-up operation. Normally, it is desirable to operate the engine at a higher cooling water temperature in terms of exhaust gas countermeasures and combustion efficiency.However, since rubber members are used for hoses connecting the engine and the radiator or for bypass passages, these In consideration of the durability of the thermostat, it is necessary to set the thermostat to open normally at about 80 ° C.

Since the thermostat is interposed in the cooling water circulation path, the thermostat has a large water flow resistance. Therefore, it is necessary to provide a relatively powerful water pump for overcoming the water flow resistance. In many cases, the rotational force of the engine crankshaft is used to drive the water pump. A burden is imposed, the engine power decreases, and the fuel efficiency increases. As described above, the thermostat has a built-in thermal expansion body such as wax that expands and contracts due to a change in cooling water temperature, and is always exposed to high temperature, high pressure, and high vibration during operation of the engine. Therefore, there is a problem that a failure due to deterioration or the like occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and shortens the warm-up time at the time of engine start, and operates the engine at a more preferable high temperature state after warm-up. It is an object of the present invention to provide a cooling device which enables the above. In addition, by removing the above-mentioned thermostat that becomes the flow resistance of the cooling water, while reducing the load on the water pump,
An object of the present invention is to provide a cooling device capable of preventing the occurrence of overheating or overcooling of an engine caused by a failure of a thermostat itself, and to reduce harmful exhaust gas and improve fuel efficiency as a whole. Things.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems.
A first fluid circulation passage communicating between a fluid passage formed in the internal combustion engine and an engine-side fluid passage formed in the first heat exchanger and containing a first cooling medium; and the first heat exchanger A fluid passage formed in the second heat exchanger and a heat radiation side fluid passage that is in thermal contact with the engine side fluid passage;
A second fluid circulation path in which a second cooling medium is stored;
It comprises a first fluid circulation means for circulating the first cooling medium in the fluid circulation path, and a second fluid circulation means for circulating the second cooling medium in the second fluid circulation path. With such a configuration, the cooling device is separated into a first fluid circulation path in which the first cooling medium is stored and a second fluid circulation path in which the second cooling medium is stored. Thus, the amount of the first cooling medium circulating in the internal combustion engine can be minimized, and the warm-up time at the time of starting the internal combustion engine can be reduced.

In this case, the heat generated from the internal combustion engine is radiated into the air by the second heat exchanger.
It is preferable to dispose the heat radiating device close to the second heat exchanger. With such a configuration, excessive heat generated by the internal combustion engine after warm-up is effectively dissipated. Preferably, the first fluid circulating means is set to an operating state during operation of the internal combustion engine, and the second fluid circulating means is configured to control operation and non-operation according to the operating state of the internal combustion engine. Is done. With this configuration, by controlling the second fluid circulation means, the temperature of the internal combustion engine can be maintained in a desired range, and the temperature control system can be simplified.

In this case, in a preferred embodiment,
A control unit that generates a control signal in response to a detection signal from at least one detection sensor that detects an operation state of the internal combustion engine; and controls the operation of the second fluid circulation unit according to a control signal from the control unit. It is configured to control the operation. Therefore, the temperature of the internal combustion engine can be more precisely controlled by the electronic action than in the conventional thermostat in which the valve is repeatedly opened and closed uniquely. In addition, the first and second 2
Since two types of cooling water having different specific heats can be used because of the two fluid circulation paths, the specific heat of the first cooling medium can be smaller than the specific heat of the second cooling medium. In this case, however, the warm-up time at the time of starting the internal combustion engine can be further reduced, which can contribute to further reducing the amount of harmful exhaust gas emissions.

In a preferred embodiment, the first fluid circulating means includes a first pump for circulating the first cooling medium in the first fluid circulating path and a first motor for driving the first pump. The second fluid circulating means is configured to circulate a second cooling medium in the second fluid circulating path.
It comprises a pump and a second motor for driving the second pump. According to this configuration, since the cooling medium is circulated by driving each motor, there is no need to use the rotational force of the internal combustion engine to drive the pump, and the load on the internal combustion engine can be reduced.

Further, in another preferred embodiment, the first fluid circulating means includes a first pump for circulating a first cooling medium in the first fluid circulating path, and the second fluid circulating means includes a first pump. The circulating means includes a second pump for circulating the second cooling medium into the second fluid circulation path, and transmits a driving force of a motor for driving the first pump to the second pump via a clutch mechanism. It is composed of Therefore,
As described above, the load on the internal combustion engine can be reduced, and the cooling medium in the two circulation paths can be circulated by one motor. Still further, by adopting a configuration in which the first heat exchanger is formed integrally with the internal combustion engine,
For example, it is possible to eliminate or minimize the connection part which requires the use of a rubber member. As a result, the normal operating temperature of the engine can be raised, and the exhaust gas can be further reduced and the fuel efficiency can be improved.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a cooling device for an internal combustion engine according to the present invention. FIG. 1 shows the overall configuration of the first embodiment. In FIG. 1, the same reference numerals as those of the conventional apparatus shown in FIG. 3 indicate corresponding parts, respectively, and accordingly, description thereof will be appropriately omitted. As shown in FIG. 1, a first heat exchanger 11 is integrally mounted on an engine 1 as an internal combustion engine. This first heat exchanger 11 has a partition wall 11a for heat exchange at the center,
The partition 11a separates the fluid passage 11b into an engine-side fluid passage 11b and a fluid passage 11c. The inflow portion 11d of the cooling water provided above the engine-side fluid passage 11b in the first heat exchanger 11 communicates with the outflow portion 1d of the cooling water provided above the engine 1. Further, an outflow portion 11 e of the cooling water provided at a lower portion of the engine-side fluid passage 11 b in the first heat exchanger 11 is communicated with an inflow portion 1 e of the cooling water provided at a lower portion of the engine 1. Thereby, the fluid passage c formed in the engine 1 and the engine-side fluid passage 11b in the first heat exchanger 11 communicate with each other, and the first fluid circulation passage 12 in which the first cooling medium is stored is formed. .

On the other hand, the cooling water outlet 1 provided above the heat-radiation side fluid passage 11c in the first heat exchanger 11
1f is connected via a cooling water passage 3a to a cooling water inflow portion 2a provided above the radiator 2 as a second heat exchanger. In addition, the cooling water inflow portion 11g provided below the heat radiation side fluid passage 11c in the first heat exchanger 11 is connected to the cooling water outflow portion 2b provided below the radiator 2 via the cooling water passage 3b. It is connected. Thus, the heat-radiation-side fluid passage 11c in the first heat exchanger 11 and the fluid passage 2c in the radiator 2 communicate with each other to form a second fluid circulation passage 13 in which the second cooling medium is stored. And, the first heat exchanger 11
The first cooling medium is supplied to the communicating portion between the outflow portion 11e of the cooling water provided at the lower portion of the engine-side fluid passage 11b and the inflow portion 1e of the cooling water provided at the lower portion of the engine 1.
A first fluid circulating means for circulating in the fluid circulating passage 12, that is, a first water pump 14 is provided.

A cooling water outflow portion 2b provided below the radiator 2 as the second heat exchanger, and a cooling water inflow portion provided below the radiation side fluid passage 11c in the first heat exchanger 11. A second fluid circulating means for circulating the second cooling medium into the second fluid circulating path 13, that is, a second water pump 15 is disposed in the communication portion with the 11 g. The first water pump 14 is driven to rotate by a first motor 16,
The second water pump 15 is connected to the second motor 17
It is configured to be driven to rotate. An outlet 1d for cooling water in the engine 1 and a first heat exchanger 11
A temperature detecting element 18, such as a thermistor, for detecting the temperature of the cooling water as the first cooling medium is disposed in a portion communicating with the cooling water inflow portion 11d. The value detected by the temperature detecting element 18 is converted into digital data by a converter 19 and supplied to a control unit (ECU) 20 for controlling the operating state of the entire engine.

Further, in the embodiment shown in FIG.
Data from a throttle position sensor 22 for detecting the opening of the throttle valve 21 of the engine 1 is also supplied to the control unit 20. Although not shown, the control unit 20 is also configured to be supplied with information such as the number of revolutions of the engine. On the other hand, from the control unit 20, the relay circuits 24, 2
The first motor 1 drives the first water pump 14 by driving these relay circuits 24, 25, 26.
6. Second motor 1 for driving second water pump 15
7 and a fan motor 6b that rotationally drives a cooling fan 6a as a heat radiating device.
It is configured to be more energized.

In the configuration shown in FIG. 1, when the engine 1 is operated, the control unit 20
, The first motor 16 is activated to drive the first water pump 14. As a result, the first cooling medium in the first fluid circulation path 12 is circulated. Water temperature information from the temperature detecting element 18 is constantly provided to the control unit 20 from the converter 19, and when the temperature of the first cooling medium (cooling water) becomes equal to or higher than a predetermined value due to heat generation after the engine is started, the control unit 20 is controlled. Urges the relay circuit 25 to activate the second motor 17 to drive the second water pump 15. This second water pump 15
Is driven by the circulating action of the second cooling medium,
The temperature of the first cooling medium in the fluid circulation path 12 is reduced to some extent. Here, when the load on the engine 1 increases and the temperature of the first cooling medium in the first fluid circulation path 12 further increases, the control unit 20 energizes the relay circuit 26, starts the fan motor 6b, and starts the radiator. The fan 6a is driven to rotate, and cooling air is forcibly taken into the radiator 2 as the second heat exchanger.

The heat generated by the operation of the engine 1 is removed from the fluid passage c in the engine 1 by the cooling water circulating in the first heat exchanger 11, and the radiator in the first heat exchanger 11 2 to the cooling water circulating between the cooling water. Then, the radiator 2 is forcibly air-cooled by the cooling fan 6a to be radiated into the air. When the heat radiation is promoted as described above and the temperature of the first cooling medium becomes equal to or lower than a predetermined value, the control unit 20 deactivates the relay circuit 25 based on the water temperature information from the temperature detecting element 18 and the second motor 17 Is stopped, and the driving of the second water pump 15 is stopped. As a result, the first
The temperature of the first cooling water in the fluid circulation path 12 rises, and by repeating this operation, the operating temperature of the engine 1 can be controlled to a substantially constant range.

In this case, the fan motor 6b generates a command signal from the control unit 20 so as to be driven to rotate at a short time after the stop of the second motor 17 (stop of driving of the second water pump 15), for example. It is made to do. Further, the control unit 20 performs a logical operation using data from a throttle position sensor 22 for detecting the opening of the throttle valve 21 of the engine 1 and data such as the number of revolutions of the engine, and drives the second water pump 15. By controlling the operations of the motor 17 and the fan motor 6b, more ideal cooling characteristics can be obtained.

According to the cooling device configured as shown in FIG. 1, the first fluid circulation path 12 and the second fluid circulation path 13 are partitioned, and the first cooling medium sealed in the first fluid circulation path 12 is provided. The amount of the medium can be much smaller than the amount of the cooling medium enclosed in the conventional cooling device shown in FIG. Therefore, the heat capacity of the engine including the cooling medium can be reduced. Then, since the cooling medium divided into the first and second fluid circulation paths and enclosed therein is circulated by the respective water pumps, the respective water pumps can be downsized. Therefore, the warm-up time of the engine after the start of the engine can be reduced, and in particular, the discharge time of a large amount of harmful exhaust gas generated at a relatively low temperature after the start of the engine can be reduced.

Further, by using a fluid having a small specific heat as the first cooling medium sealed in the first fluid circulation path 12,
The above action can be further promoted. further,
By adopting a configuration in which the first heat exchanger is formed integrally with the engine 1, for example, it is possible to eliminate or minimize the connecting portion that has to use a rubber member. Thus, as described above, the normal operating temperature of the engine can be increased, and the exhaust gas can be further reduced and the fuel efficiency can be improved.

FIG. 2 shows a configuration of a main part according to a second embodiment of the present invention. In the embodiment shown in FIG. 2, the same reference numerals as those in FIG. 1 indicate corresponding parts. In the configuration shown in FIG. 2, the first pump 14 for circulating the first cooling medium in the first fluid circulation path
Is driven by a motor 31.
The clutch mechanism 32 is interposed between the drive shaft 14a of the first pump 14 and the drive shaft 15a of the second pump 15 for circulating the second cooling medium in the second fluid circulation path. The clutch mechanism 32 includes, for example, two clutch plates 32a and 32b. The clutch plates 32a and 32b are released by the operation of the electromagnetic plunger 33, and the clutch plates 32a and 32b are released by the non-operation of the electromagnetic plunger 33.
Are connected. The electromagnetic plunger 33 is connected to a battery via a relay 34, and the relay 34 is configured to be energized and deenergized by the control unit 20. The other configuration is the same as that of the first embodiment shown in FIG.

In the above configuration, when the engine 1 is in the operating state, the control unit 20 activates the motor 31 to drive the first water pump 14. As a result, the first cooling medium in the first fluid circulation path 12 is circulated as in the embodiment shown in FIG. At this time, the control unit 20 energizes the relay circuit 34, and the electromagnetic plunger 33 operates to release the pair of clutch plates 32a and 32b in the clutch mechanism 32. Therefore, the second water pump 15 is not driven. When the temperature of the first cooling medium (cooling water) becomes equal to or higher than a predetermined value due to heat generated by the engine, the control unit 20 deenergizes the relay circuit 34,
Thereby, the energization to the electromagnetic plunger 33 is cut off.
As a result, the pair of clutch plates 32a and 32b in the clutch mechanism 32 are brought into a connected state, and the second water pump 15 is driven. The heat generated by the operation of the engine in this way is radiated through the first heat exchanger 11 by the radiator 2 as a second heat exchanger.

When the heat radiation is promoted and the temperature of the first cooling medium becomes equal to or lower than a predetermined value, the control unit 20 energizes the relay circuit 34 to stop driving the water pump 15 in the same manner as described above. By repeating the above, the operating temperature of the engine can be controlled within a substantially constant range. The clutch mechanism 32 is of a normally closed type that is connected when the electromagnetic plunger 33 is not energized. Therefore, the relay circuit 34 and the electromagnetic plunger 33 that is energized by the relay circuit 34 are controlled. Even if a failure occurs, the clutch mechanism 32 is connected to perform a fail-safe function of preventing the engine 1 from overheating.

In the embodiment described with reference to FIG. 1, a second water pump and a second motor for driving the water pump are provided to circulate the cooling water in the second fluid circulation path. However, the cooling water in the second fluid circulation path may be configured to circulate by, for example, natural convection, and in this case, the size of the cooling device can be reduced. Although the cooling device for an automobile engine has been described above as an example, the present invention is not limited to such a specific device, and the same operation and effect can be obtained by applying the invention to other internal combustion engines. Can be.

[0027]

As described above, according to the internal combustion engine cooling apparatus of the present invention, a first fluid circulation path is formed between the internal combustion engine and the first heat exchanger, and the first heat exchanger and the second heat exchanger are formed.
Since the second fluid circulation path is formed between the heat exchanger and the second heat exchanger, the heat from the internal combustion engine is dissipated in the second heat exchanger. Therefore, the warm-up time of the engine after the start of the internal combustion engine can be reduced. In addition, generation of harmful exhaust gas can be reduced. Further, since there is no need to interpose a thermostat that expands and contracts due to heat in the circulation path of the cooling medium, the water flow resistance in the fluid circulation path can be significantly reduced. Therefore, the circulation of the cooling medium can be realized by the motor driven by the battery without using the rotational force of the engine. In this case, the load on the engine can be reduced, and the fuel efficiency can be improved. Furthermore, when the first heat exchanger is integrally formed on the engine side, it is possible to reduce or eliminate the connection portion of the fluid circulation path using a rubber member. Further, since the influence of the hysteresis characteristic due to the thermostat can be removed, the operating temperature of the engine can be increased to an ideal constant temperature, and the exhaust gas can be further reduced and the fuel efficiency can be further improved.

[Brief description of the drawings]

FIG. 1 is a first view of a cooling device for an internal combustion engine according to the present invention.
FIG. 2 is a configuration diagram showing an embodiment.

FIG. 2 is a configuration diagram showing a main part of the second embodiment.

FIG. 3 is a configuration diagram showing an example of a conventional cooling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal-combustion engine (engine) 2 2nd heat exchanger (radiator) 3 Cooling water path 6 Fan unit 6a Cooling fan 6b Fan motor 11 1st heat exchanger 11a Partition wall 11b Engine side fluid path 11c Radiation side fluid path 12 First fluid circulation path 13 2nd fluid circulation path 14 1st water pump (1st fluid circulation means) 15 2nd water pump (2nd fluid circulation means) 16 1st motor 17 2nd motor 18 Temperature detection element 20 Control unit (ECU) 21 Throttle valve 23 Battery 31 Motor 32 Clutch mechanism 32a Clutch plate 32b Clutch plate 33 Electromagnetic plunger c Fluid passage in internal combustion engine

Claims (8)

[Claims] A fluid passage formed in an internal combustion engine and a first fluid passage.
A first fluid circulation path communicating with an engine-side fluid passage formed in the heat exchanger and containing a first cooling medium; and a heat radiation that is in thermal contact with the engine-side fluid passage of the first heat exchanger. A second fluid circulation passage communicating between the side fluid passage and a fluid passage formed in the second heat exchanger and accommodating a second cooling medium; and a first cooling medium in the first fluid circulation passage. A cooling device for an internal combustion engine, comprising: a first fluid circulation means for circulating; and a second fluid circulation means for circulating a second cooling medium in the second fluid circulation path. 2. The heat generated by the internal combustion engine is transferred to the second engine.
2. The cooling device for an internal combustion engine according to claim 1, wherein a heat radiating device is arranged close to the second heat exchanger so that the heat is radiated into the air by the heat exchanger. 3. The first fluid circulating means is in an operating state during operation of the internal combustion engine, and the second fluid circulating means is
3. The cooling device for an internal combustion engine according to claim 1, wherein operation and non-operation are controlled in accordance with an operation state of the internal combustion engine. 4. A control unit for generating a control signal in response to a detection signal from at least one detection sensor for detecting an operation state of the internal combustion engine, wherein the second fluid circulation is performed by a control signal from the control unit. 4. The cooling device for an internal combustion engine according to claim 3, wherein operation and non-operation of the means are controlled. 5. The internal combustion engine according to claim 1, wherein the specific heat of the first cooling medium is smaller than the specific heat of the second cooling medium. Engine cooling system. 6. The first fluid circulation means comprises a first pump for circulating a first cooling medium in a first fluid circulation path, and a first motor for driving the first pump. 6. The two-fluid circulation means comprises a second pump for circulating the second cooling medium in the second fluid circulation path, and a second motor for driving the second pump. The cooling device for an internal combustion engine according to any one of the above. 7. The first fluid circulation means includes a first pump for circulating a first cooling medium in a first fluid circulation path, and the second fluid circulation means includes a second cooling medium. A second pump for circulating the fluid in the second fluid circulation path, and transmitting a driving force of a motor for driving the first pump to the second pump via a clutch mechanism. The cooling device for an internal combustion engine according to any one of claims 1 to 5. 8. The cooling device for an internal combustion engine according to claim 1, wherein the first heat exchanger is formed integrally with the internal combustion engine.