JP2000257430A - Internal combustion engine cooling system - Google Patents

Abstract

(57) Abstract: Provided is a cooling device for an internal combustion engine that can suitably avoid overheating at the time of engine start even when pure water is used as a cooling liquid and the pure water is frozen. . A cooling device includes a water jacket provided in an engine, a coolant, a thermo housing, a reserve tank, a radiator, and an antifreezing tube.
5, a freeze prevention mechanism 7, a water pump 8, and the like. The anti-freezing mechanism 7 includes a controller 71, an electric pump 72, an electromagnetic switching valve 73, a coolant temperature sensor 74, a thermostat 76, and communication paths 77a, 77b, 7
7c and an outside air temperature sensor 78. The anti-freezing mechanism 7 collects the partial cooling liquid 3 in the anti-freezing tube 75 and the water jacket 2 into the reserve tank 5 before the outside temperature drops and the cooling liquid 3 freezes when the engine is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling apparatus for cooling an internal combustion engine by circulating a cooling liquid in a cooling passage, and more particularly to a cooling apparatus for an internal combustion engine using pure water as a cooling liquid. .

[0002]

2. Description of the Related Art Conventionally, as a cooling device for an internal combustion engine of this type, for example, a device described in Japanese Patent Application Laid-Open No. 8-112167 is known.

In this apparatus, pure water, which does not require periodic replacement due to thermal deterioration and does not require recovery processing for environmental protection, is used instead of an antifreeze such as LLC (long life coolant) as a coolant. The use makes the maintenance easy. In addition, the device detects the amount of dissolved oxygen in the coolant in order to maintain a high corrosion prevention function over a long period of time, and when the detected amount exceeds a predetermined value, the oxygen reduction mechanism causes the dissolved oxygen to be detected. The amount is reduced.

Usually, when pure water is used as the cooling liquid, the volume expansion during freezing cannot be ignored. That is, if the cooling liquid composed of the pure water remains in the water jacket of the internal combustion engine and freezes, the internal combustion engine may be damaged due to the volume expansion. Therefore, the device further detects the temperature of the coolant, and when the detected temperature drops to a predetermined value, extracts a part of the coolant in the cooling passage and supplies the inert gas to the cooling passage. To form a gas phase,
The volume expansion due to the freezing of the cooling liquid (pure water) is absorbed by the formed gas phase.

[0005]

In the above-described conventional cooling apparatus, the volume expansion during freezing of the cooling liquid (pure water) can be avoided in the above-described manner. When the liquid is frozen, the possibility of overheating of the engine is unavoidable at the time of an excessive load immediately after the start of the liquid. This is because if the coolant (pure water) in the radiator is frozen when the engine is started, even if the engine is overloaded immediately after the start,
This is because the circulation of the cooling liquid for releasing the heating due to this cannot be made in time, and although over time, an overheating state is eventually required.

[0006] The present invention has been made in view of such circumstances, and its purpose is to prevent overheating when starting the engine even when pure water is used as a cooling liquid and the water is frozen. Another object of the present invention is to provide a cooling device for an internal combustion engine which can be avoided.

[0007]

In order to achieve the above object, the invention according to the first aspect of the present invention is directed to a method in which a cooling liquid composed of pure water is absorbed between an internal combustion engine and a radiator while absorbing a change in volume through a storage tank. In the cooling device of the internal combustion engine, which cools the coolant based on heat exchange between the coolant and the internal combustion engine, the forced circulation of the coolant through at least the engine when the internal combustion engine is started is performed. The gist of the present invention is to provide a forced circulation passage that makes it possible.

[0008] In this configuration, a forced circulation passage is provided which enables forced circulation of the coolant through at least the engine when the internal combustion engine is started. Therefore, even when the internal combustion engine is started in a state where the coolant is frozen, the circulation of the coolant via the forced circulation passage is started early. As a result, overheating is suitably prevented even at the time of overload immediately after the start of the internal combustion engine. Further, since the volume expansion and the like of the cooling liquid are absorbed through the storage tank, unnecessary stress due to the volume expansion is hardly applied to the internal combustion engine.

According to a second aspect of the present invention, in the cooling device for an internal combustion engine according to the first aspect, the forced circulation passage circulates the forced circulation of the coolant through the engine through the interior of the radiator. The gist is to make it possible.

Even if the coolant in the radiator is frozen, the coolant in the radiator is eventually thawed while the forced circulation of the coolant by the forced circulation passage is repeated with the start of the engine. However, when a part of the forced circulation passage is directly interposed in the radiator as in the same configuration, the thawing of the coolant in the radiator is further promoted.

According to a third aspect of the present invention, in the cooling device for an internal combustion engine according to the first or second aspect, the forced circulation passage includes an anti-freezing mechanism for preventing a cooling liquid from freezing in the passage. The main point is that

According to the above configuration, it is ensured that a forced circulation passage enabling the forced circulation of the coolant at the time of starting the internal combustion engine is secured. According to a fourth aspect of the present invention, in the cooling device for an internal combustion engine according to the third aspect, the anti-freezing mechanism detects a temperature of a coolant in the forced circulation passage, and a detection of the coolant temperature. Forming a coolant flow path between the forced circulation passage and the storage tank under the condition that the temperature of the coolant to be cooled is a temperature immediately before freezing and solidification; The gist of the invention is to provide a discharge control unit for forcibly discharging the cooling liquid to the storage tank.

With this configuration, at least at the time of starting the engine, the coolant is kept in the liquid phase or the gaseous phase without being frozen in the forced circulation passage. Therefore, when the engine is started, the forced circulation of the coolant through the forced circulation passage is also ensured. Further, when the inside of the forced circulation passage is kept in the gaseous phase, the volume of the coolant expands when the freezing liquid freezes, but the expanded portion is suitably absorbed by the gaseous phase portion.

According to a fifth aspect of the present invention, in the cooling device for an internal combustion engine according to the fourth aspect, the freeze prevention mechanism further includes an outside air temperature detecting section for detecting the temperature of outside air, and the discharge control section includes: Under the condition that the detected outside air temperature is equal to or lower than the freezing point temperature, the gist is that the coolant is activated for a predetermined time required for forcibly discharging the coolant in the forced circulation passage.

According to this configuration, the discharge control section becomes active only for a predetermined time required for forcibly discharging the coolant in the forcible circulation passage on condition that the outside air temperature is lower than the freezing point temperature. Therefore, power consumption during engine stoppage can be minimized.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a cooling device according to the present invention will be described below with reference to FIGS.

FIG. 1 schematically shows the structure of a cooling device according to the present embodiment, and it is assumed that the cooling target is an engine mounted on an automobile. As shown in FIG. 1, the present cooling device is roughly
The engine includes a water jacket 2, a coolant 3, a thermo-housing 4, a reserve tank (storage tank) 5, a radiator 6, an antifreeze tube 75 and an antifreeze mechanism 7, a water pump 8, and the like provided in the engine. You. In the present embodiment, pure water composed of distilled water is used as the cooling liquid 3. As described above, this pure water is a desirable liquid for the cooling liquid 3, which does not require periodic replacement due to thermal deterioration even after long-term use even though it is frozen, and does not require recovery processing for environmental protection. It is as follows.

The water jacket 2 is provided inside each of the cylinder block 1 and the cylinder head 1a of the engine. The radiator 6 is disposed in front of the engine (left side in FIG. 1) and includes an upper tank 63, a plurality of tubes 61, fins 62, a lower tank 64, and the like. The upper tank 63 is connected to the water jacket 2 via an outlet hose 91. On the other hand, the lower tank 64 is connected to the water jacket 2 via the inlet hose 92, the thermohousing 4, the passage 93, and the water pump 8. And, these water jacket 2, outlet hose 91, radiator 6, inlet hose 9
2. The thermo-housing 4, the passage 93, and the water pump 8 form a closed circulation path (cooling path). Note that the coolant 3 in the circulation path is sealed in a production plant of an automobile or the like.

The thermo-housing 4 has a thermostat 41 therein, and automatically switches the circulation path of the coolant 3 according to the temperature of the coolant 3. That is, when the temperature of the coolant 3 is still low, for example, when the engine is started, the bypass passage 94 communicates with the passage 93 (between the ports GH) to form a bypass passage for the coolant 3. On the other hand, when the temperature of the coolant 3 rises above a predetermined value, the inlet hose 92 and the passage 93 (port E
-H) to form the circulation path.

In this thermo housing 4,
The port DH and the port F-H are always in communication. Also, when the engine is started when the coolant 3 described later is frozen, first, between the ports DH,
In addition, communication between the ports GH is added, and then communication between the ports F and H is added. Further, when the coolant 3 is at a high temperature, the ports GH are closed and communication between the ports E and H is added. It becomes an aspect.

The water pump 8 is connected to a crankshaft (not shown) by pulleys, belts, and the like, and is operated by rotation of the crankshaft accompanying the operation of the engine. The water pump 8 sucks the coolant 3 in the passage 93 and discharges the coolant 3 to the water jacket 2. Due to the suction and discharge, the coolant 3 circulates in the circulation path (or the bypass path) in a manner indicated by an arrow in FIG. During this circulation, the coolant 3 absorbs heat of the engine and rises in temperature while passing through the water jacket 2. Heated coolant 3
Radiates its own heat when passing through the tube 61 of the radiator 6. Thus, each part of the engine is cooled by heat exchange between the coolant 3 and the engine.

Further, a reserve tank 5 for absorbing a volume change of the cooling liquid 3 caused by a temperature change is connected to the cooling device. That is, the coolant 3 in the circulation path expands in volume due to a rise in temperature due to the heat exchange, and the amount of the expansion is reduced by the reserve tank inlet hose 5.
It is sent to the reserve tank 5 through 3 and stored there. The stored cooling liquid 3 is returned to the circulation path via a passage 95 connected to a lower part of the reserve tank 5 in a state where the volume of the cooling liquid 3 is reduced due to a temperature decrease.

A liquid layer 51 formed by storing the cooling liquid 3 and a gas layer 52 filled with air or the like are formed in the reserve tank 5. A thermostat 76 is provided in the middle of the passage 95. The thermostat 76 conducts the passage 95 when the temperature of the coolant 3 rises above a predetermined value, and moves the coolant 3 in the reserve tank 5 into the thermohousing 4.

In the cooling device according to this embodiment, at least the antifreeze tube 75 that enables forced circulation of the coolant 3 through the engine at the time of engine start is provided in order to prevent overheating at the time of engine start. It has a forced circulation passage configured and a freezing prevention mechanism 7 thereof.

The anti-freezing mechanism 7 includes a controller 71, an electric pump 72, an electromagnetic switching valve 73, a coolant temperature sensor 74, a thermostat 76, and communication paths 77a, 77b, 7
7c and an outside air temperature sensor 78.

In this embodiment, an antifreeze tube 75 is provided in the radiator 6, and one end thereof is connected to an upper tank 63 of the radiator 6.
The other end is connected to an electromagnetic switching valve 73. The antifreezing tube 75 is provided with a coolant temperature sensor 74 for measuring the temperature of the coolant 3 therein, and the sensor 74 is connected to the controller 71.

The electromagnetic switching valve 73 is further connected to communication paths 77a and 77b. The other end of the communication path 77a is connected to the thermo-housing 4, while the other end of the communication path 77b is electrically driven. It is connected to a pump 72. Further, a communication passage 77c is connected to the electric pump 72, and the other end of the communication passage 77c is connected to the reserve tank 5c.
It is connected to the upper gas layer 52.

An outside air temperature sensor 78 for detecting the outside air temperature
Is provided at a predetermined position.
1 connected. The electromagnetic switching valve 73
And the control of the anti-freezing mechanism 7, including the drive control of the electric pump 72, is performed based on a command from the controller 71.

Next, the process of preventing the freezing prevention tube 75 from freezing by the above-described freezing prevention mechanism 7 based on a command from the controller 71 will be described with reference to the flowchart of FIG. This process is always executed regardless of the operating state of the engine (including when the engine is stopped) by the interrupt process at predetermined time intervals. That is, power is supplied to the electric components constituting the freeze prevention mechanism 7 even when the ignition switch is in an OFF state.

In the freezing prevention process, the controller 71 first reads the state of the ignition switch in step 101, that is, the ignition information and the outside air temperature Tg detected by the outside air temperature sensor 78, and then in step 102, the ignition switch turns on the ignition switch. It is determined whether it is OFF. If the ignition switch is not OFF, that is, if the ignition switch is ON, it is determined that the engine is being started, and this process is temporarily terminated.

On the other hand, if the ignition switch is OFF, the routine goes to step 103, where the outside air temperature Tg is 0 ° C.
Thereafter, it is determined whether the temperature is below the freezing point temperature.
When the outside air temperature Tg exceeds 0 ° C., it is determined that the temperature of the cooling liquid 3 is not so low and there is no freezing, and thus this processing is once ended.

On the other hand, if the outside air temperature Tg is equal to or lower than 0 ° C., the process proceeds to step 104, and the controller 71 sets the anti-freezing tube 75 detected by the coolant temperature sensor 74.
The temperature Tw of the cooling liquid 3 inside is read. In the subsequent step 105, the controller 71 determines whether or not the read coolant temperature Tw is in a range of, for example, 1 to 5 ° C., that is, in a temperature range before solidification due to freezing. Then, for example, immediately after the engine is stopped, if the liquid temperature Tw has not yet fallen to the range of 1 to 5 ° C., this process is temporarily ended.

On the other hand, if the coolant temperature Tw has fallen to the range of 1 to 5 ° C., the routine proceeds to step 106, where the controller 71 operates the electromagnetic switching valve 73 to close the valve B, and at the same time to close the valves A and The valve C is opened, and the electric pump 72 is operated for a predetermined time (several minutes). As a result, the coolant 3 in the antifreeze tube 75 communicates with the communication passage 77b.
And moves to the reserve tank 5 via 77c. That is, the coolant 3 in the antifreeze tube 75 is forcibly drained (recovered) into the reserve tank 5 before freezing. At this time, the passage 95 is closed by a thermostat 76 provided on the way. During the predetermined time (several minutes) during which the electric pump 72 is operated to forcibly drain (recover) the coolant 3, the coolant 3 in the upper tank 63, the outlet hose 91, and the upper part of the cylinder head 1 a is also removed. The collection time is determined in advance by experiments and the like.

At the time of collecting the cooling liquid 3, air from the reserve tank 5 flows through the reserve tank inlet hose 53 due to the pressure reduction in the path from the antifreeze tube 75 to the upper part of the cylinder head 1 a. To form a gas phase portion. The volume change of this gas phase portion is easier than that of the liquid phase portion (cooling liquid 3). Therefore, even if the outside air temperature drops to 0 ° C. or less and the coolant 3 remaining on the cylinder block 1 and the cylinder head 1 a (in the water jacket 2) freezes and expands in volume, this expansion component remains in the same gas phase. It will be absorbed by the part.
As a result, breakage of the cylinder block 1 and the cylinder head 1a due to the volume expansion of the coolant 3 can be prevented.

When the collection of the coolant 3 for the predetermined time is completed, the controller 71 subsequently operates the electromagnetic switching valve 73 to close the valve A and open the valves B and C in step 107. Thus, when the engine is started, the above-described anti-freeze tube 75
Is moved into the thermo-housing 4 via the communication path 77a, and a circulation path (forced circulation path) is secured. As described above, the controller 71 ends the freeze prevention process and prepares for starting the engine.

As described above, in the present embodiment, when the ignition switch is turned off, the coolant temperature Tw becomes 1 to
When the temperature drops to the range of 5 ° C., the antifreeze tube 75, the upper tank 63, the outlet hose 91,
The coolant 3 in the upper part of the cylinder head 1a is forcibly discharged (recovered) to the reserve tank 5 before freezing. When the cooling liquid 3 is collected, the above-mentioned antifreeze tube 75
A gaseous phase portion is formed in a path extending from inside to the upper portion of the cylinder head 1a.

Therefore, even when the remaining coolant 3 and the coolant 3 in the radiator 6 are frozen at the time of starting the engine, the frozen coolant in the water jacket 2 is not affected by the start of the engine. When the cooling liquid 3 is dissolved, the circulation path of the cooling liquid 3 is secured by a path passing through the antifreezing tube 75 and the like in which the gas phase is formed. Therefore, even when the engine is started while the coolant 3 is frozen, the circulation of the coolant 3 is started early, and the dissolution of the coolant 3 in the frozen radiator 6 is promoted. As a result, overheating of the engine can be appropriately prevented even at the time of overload immediately after the start of the engine.

In the present embodiment, the coolant 3
Immediately after the start of the engine at the time of freezing, the coolant 3 in the engine has a form in which a gas phase is mixed. However, during the operation of the engine, the circulation path is a completely closed system. Gas-liquid separation is performed. Therefore, when the temperature of the coolant 3 rises, the conventional cooling of the engine is realized.

As described above, according to the internal combustion engine cooling apparatus of the present embodiment, the following effects can be obtained. (1) In the present embodiment, even when the remaining coolant 3 and the coolant 3 in the radiator 6 are frozen at the time of starting the engine, the water jacket 2 is kept at the same time as the engine is started. When the frozen cooling liquid 3 is melted, the circulation path of the cooling liquid 3 is secured in a path (forced circulation path) passing through the antifreezing tube 75. Therefore, even when the engine is started in a state where the coolant 3 is frozen, the circulation of the coolant 3 is started at an early stage, and the dissolution of the coolant 3 in the frozen radiator 6 is promoted. As a result, at the time of overload immediately after the start of the engine, overheating of the engine is suitably prevented.

(2) In the present embodiment, the freezing of the coolant 3 in the forced circulation passage (such as the antifreezing tube 75) is prevented by the antifreezing mechanism 7 constituted by the controller 71 and the like. Therefore, a forced circulation passage that enables the forced circulation of the coolant 3 at the time of starting the internal combustion engine is reliably secured.

(3) In the present embodiment, before the coolant 3 in the upper part of the cylinder head 1a is frozen from the antifreeze tube 75, the discharge control unit such as the electromagnetic switching valve 73 and the electric pump 72, etc. Is forcibly discharged to the reserve tank 5. At this time, a gas phase portion filled with air or the like is formed in a path (forced circulation path) extending from the freeze prevention tube 75 to the upper portion of the cylinder head 1a. The volume change of this gas phase portion is easier than that of the liquid phase (cooling liquid 3). Therefore, even if the outside air temperature drops to 0 ° C. or less and the coolant 3 remaining in the cylinder block 1 and the cylinder head 1 a (in the water jacket 2) freezes and expands in volume, the amount of the expansion is reduced by the gas phase It will be absorbed by the part. As a result, damage to the cylinder block 1 and the cylinder head 1a due to the volume expansion of the coolant 3 can be prevented.

(4) The discharge control section such as the electric pump 72 is driven only for a predetermined time on condition that the outside temperature Tg is equal to or lower than the freezing point temperature, so that power consumption while the engine is stopped is minimized. be able to.

(5) In the present embodiment, the coolant 3
The pure water used as is different from an antifreeze such as LLC or the like, and always maintains a stable state, and does not change (degrade) even when used for a long period of time. That is, since the cooling liquid 3 made of pure water does not change with time, there is no need to replace it. In addition, the cooling liquid 3 composed of pure water alone can conduct heat more easily (has a higher thermal conductivity) and has higher thermal efficiency than the cooling liquid using LLC, so that the size of the radiator 6 can be reduced. Further, at the time of scrapping the vehicle, no special treatment is required when disposing of the cooling liquid 3, thereby conserving the environment.

The above-described embodiment can be modified and implemented as follows. In the above embodiment, the conditions for forcibly discharging the coolant 3 to the reserve tank 5 are that the outside air temperature Tg is equal to or lower than the freezing point temperature and the coolant temperature Tw is reduced to a range of 1 to 5 ° C. The present invention is not limited to this, and the same condition may be applied only when the coolant temperature Tw is reduced to a range of 1 to 5 ° C. That is, in the above-described freezing prevention processing, the determination processing shown in step 103 may be omitted.

In the above embodiment, the temperature range before the cooling liquid is solidified by freezing is 1 to 5 ° C., but the temperature range is not limited to this, and the same range may be, for example, 1 to 4 ° C., 2 to 3 ° C., etc. Optional.

In the above embodiment, the reserve tank 5
Although the gas layer 52 is an air layer, the gas layer 52 may be a nitrogen gas layer by filling a nitrogen gas which is an inert gas into the reserve tank 5.

In the above embodiment, the antifreeze tube 75 is provided in the radiator 6, but the invention is not limited to this. For example, one end of the antifreeze tube 75 may be branched from the outlet hose 91, and the other end may be connected to the electromagnetic switching valve 73.

Further, it is not limited that the forced-circulation passage for the coolant is constituted by the antifreezing tube 75 or the like. The essential point of the circulation passage is that at least when the internal combustion engine is started, the coolant passes through the engine. What is necessary is just to make the forced circulation possible.

[0049]

According to the first aspect of the present invention, when the internal combustion engine is started, at least the forced circulation passage for enabling the forced circulation of the coolant through the engine is provided, so that the internal combustion engine in a state where the coolant is frozen is provided. Also at the time of starting, the circulation of the coolant through the forced circulation passage is started early. As a result, overheating is suitably prevented even at the time of overload immediately after the start of the internal combustion engine.

According to the second aspect of the present invention, the thawing of the cooling liquid in the radiator is further promoted. Claim 3
According to the invention, it is ensured that a forced circulation passage enabling the forced circulation of the coolant at the time of starting the internal combustion engine is secured.

According to the fourth aspect of the present invention, when the engine is started, the forced circulation of the coolant through the forced circulation passage is reliably ensured. When the inside of the forced circulation passage is kept in the gaseous phase, the volume expansion when the coolant is frozen is suitably absorbed by the gaseous phase portion.

According to the fifth aspect of the invention, the power consumption during the stop of the engine can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram schematically showing the configuration of an embodiment of a cooling device for an internal combustion engine of the present invention.

FIG. 2 is an exemplary flowchart showing a freeze prevention processing procedure by the freeze prevention mechanism of the embodiment.

[Explanation of symbols]

2 ... water jacket, 3 ... coolant, 4 ... thermo housing, 5 ... reservoir, 6 ... radiator, 7 ... freezing prevention mechanism, 8 ... water pump, 53 ... reservoir inlet hose, 63 ... upper tank, 64 ... lower tank 71: controller, 72: electric pump, 73
... Electromagnetic switching valve, 74 ... Coolant temperature sensor, 75 ... Freezing prevention tube, 76 ... Thermostat, 77 ... Communication passage, 78 ... Outside air temperature sensor, 91 ... Outlet hose,
92: an inlet hose, 93: a passage, 94: a bypass passage.

Claims (5)

[Claims] 1. A cooling liquid made of pure water is circulated between an internal combustion engine and a radiator while absorbing a change in the volume of the cooling liquid through a storage tank, based on heat exchange between the cooling liquid and the internal combustion engine. A cooling device for an internal combustion engine that cools the engine, comprising: a forced circulation passage that enables forced circulation of at least the coolant through the engine when the internal combustion engine is started. 2. A cooling device for an internal combustion engine according to claim 1, wherein said forced circulation passage enables forced circulation of said coolant through said engine through said radiator. 3. The cooling device for an internal combustion engine according to claim 1, wherein the forced circulation passage includes an anti-freezing mechanism for preventing a cooling liquid from freezing in the passage. Engine cooling system. 4. A cooling liquid temperature detecting section for detecting a temperature of a cooling liquid in the forced circulation passage, and a condition that the detected temperature of the cooling liquid is a temperature immediately before freezing and solidification. A discharge control unit for forming a coolant passage between the forced circulation passage and the storage tank, and forcibly discharging the coolant in the forced circulation passage to the storage tank through the formed passage. The cooling device for an internal combustion engine according to claim 3, wherein the cooling device is configured. 5. The cooling device for an internal combustion engine according to claim 4, wherein said anti-freezing mechanism further comprises an outside air temperature detecting section for detecting the temperature of outside air, and said discharge control section comprises: A cooling device for an internal combustion engine, wherein the cooling device is activated only for a predetermined time required for forcibly discharging the coolant in the forced circulation path on condition that the temperature is equal to or lower than a temperature.