JP2013044281A - Cooling apparatus for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for suppressing deterioration in cooling performance and reliability in a cooling apparatus for an internal combustion engine using a variable specific heat cooling water in which specific heat in a predetermined temperature range takes a value larger than specific heat other than the predetermined temperature range.SOLUTION: The cooling apparatus for the internal combustion engine uses, as a heat medium, cooling water in which specific heat in the predetermined temperature range takes the value larger than specific heat other than the predetermined temperature range by containing a heat storage capsule filled inside with a latent heat storage material whose phase is transferred in the predetermined temperature range in a temperature range that cooling water can take. The cooling apparatus includes a cooling water passage through which the cooling water flows; a flow regulating means that can regulate the flow of the cooling water that flows through the cooling water passage; and a control means for controlling the flow regulating means so that the flow of the cooling water at least at a part of the cooling water passage becomes larger than a predetermined threshold when a state of the cooling water flow at least at the part of the cooling water passage being the predetermined threshold or less continues for a predetermined time or longer.

Description

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

  As a cooling water for cooling the internal combustion engine, it contains a heat storage capsule that encloses a heat storage material that changes between a solid phase state and a liquid phase state, or between a liquid phase state and a gas phase state. A cooling device using variable specific heat cooling water whose specific heat changes at the phase transition temperature is disclosed (for example, see Patent Document 1). By using variable specific heat cooling water mixed with such latent heat storage material, heat can be transported efficiently, and the circulation amount of cooling water by the pump can be reduced by that amount, and the heat source to be cooled The cooling efficiency can be improved.

  Patent Document 2 discloses a cooling control system for an internal combustion engine in which the flow rate of the cooling water is variable according to the concentration of the cooling liquid (LLC) contained in the cooling water.

JP 2009-044896 A JP 2007-211671 A

  In a cooling device using variable specific heat cooling water containing a heat storage capsule enclosing such a latent heat storage material, if the flow rate of the cooling water is low for a long time, the cooling water stays and the heat storage capsule is locally There is a possibility that a dense part or a scattered part may occur. If the heat storage capsule concentration of the variable specific heat cooling water varies depending on the location in the cooling water path, the cooling performance and reliability of the cooling water may be affected.

  Accordingly, an object of the present invention is to reduce cooling performance and reliability in a cooling device for an internal combustion engine that uses variable specific heat cooling water in which specific heat in a predetermined temperature range takes a value larger than that in other than the predetermined temperature range. It is in providing the technique which suppresses.

  The present invention includes a heat storage capsule enclosing therein a latent heat storage material that undergoes phase transition in a predetermined temperature range within which the cooling water can take, so that the specific heat in the predetermined temperature range is other than the predetermined temperature range. A cooling device for an internal combustion engine that uses cooling water having a value larger than the specific heat as a heat medium, wherein the cooling water passage through which the cooling water flows and the flow rate of the cooling water through the cooling water passage can be adjusted. When the state in which the flow rate of the cooling water in the flow rate adjusting means and at least a part of the cooling water passage is below a predetermined threshold continues for a predetermined time or longer, the flow rate of the cooling water in at least the part becomes larger than the threshold value. And a control means for controlling the flow rate adjusting means.

  Here, the predetermined temperature range is a temperature at which the latent heat storage material undergoes phase transition, and is a specific temperature or a temperature range. In the present specification, these are collectively referred to as a temperature range. In the predetermined temperature range, the latent heat storage material enclosed in the heat storage capsule undergoes phase transition, so that the latent heat storage material releases or absorbs heat, so that the specific heat of the cooling water becomes larger than the other temperature ranges. For this reason, in the predetermined temperature range, even if heat enters and exits, the temperature of the cooling water becomes substantially constant.

  Further, the predetermined threshold value and the predetermined time are determined in advance based on the lower limit value of the flow rate of the cooling water and the upper limit value of the duration time of the flow rate so that the heat storage capsules are not locally concentrated in the cooling water passage. That is, if the flow rate of the cooling water flowing through the cooling water passage is larger than the threshold value, the heat storage capsules are prevented from being locally concentrated in the cooling water passage regardless of the duration of the flow rate state.

  According to the present invention, in at least a part of the cooling water passage, when the state in which the flow rate of the cooling water is equal to or lower than the predetermined threshold value continues for a predetermined time or longer, the flow rate of the cooling water is forcibly made larger than the threshold value. Thereby, since a thermal storage capsule comes to disperse | distribute uniformly within a cooling water channel | path, it can suppress that a thermal storage capsule gathers locally within a cooling water channel | path. Accordingly, it is possible to suppress a decrease in cooling performance and reliability of the cooling device.

  Note that the control means may return the control of the flow rate of the cooling water to the normal control after a certain period of time has elapsed since the start of the control of the flow rate adjustment means so that the flow rate of the cooling water becomes larger than the threshold value. The normal control is control for adjusting the flow rate of the cooling water based on a map or a relational expression determined in advance according to the operating state of the internal combustion engine, the cooling water temperature, or the like. In this way, excessive or insufficient cooling of the internal combustion engine due to the forced control of the flow rate of the cooling water to a threshold value or higher can be suppressed.

  In the present invention, a radiator provided in the cooling water passage for removing heat from the cooling water, a bypass passage for bypassing the radiator, and when closed, the flow of the cooling water to the radiator is shut off to the bypass passage. When the cooling water is circulated and opened, at least the radiator circulates the cooling water and can be opened and closed regardless of the temperature of the cooling water, and the control means has a predetermined state in which the thermostat is closed. When it continues for more than the time, the thermostat may be opened and the flow rate adjusting means may be controlled so that the flow rate of the cooling water in the radiator becomes larger than a threshold value.

  When the thermostat is closed, the cooling water stays in the radiator, so that the flow rate of the cooling water flowing through the radiator is equal to or less than the threshold value. Since the radiator has a relatively narrow passage due to its structure, if the cooling water is accumulated, the heat storage capsules may be locally concentrated and cause clogging. According to the above configuration, when the state where the thermostat is closed continues for a predetermined time or longer, the thermostat is forcibly opened and the flow rate of the cooling water flowing through the radiator is forcibly made larger than the threshold value. It is possible to suppress the heat storage capsule from being locally concentrated inside. Accordingly, it is possible to suppress a decrease in cooling performance and reliability of the cooling device.

  In the present invention, when the internal combustion engine is started after the predetermined time has elapsed after the internal combustion engine is stopped, the flow rate of the cooling water flowing through the cooling water passage becomes larger than the threshold value. In this way, the flow rate adjusting means may be controlled.

  When the water pump is also stopped when the internal combustion engine is stopped, the cooling water stays in the entire cooling water passage, and the flow rate of the cooling water flowing through the cooling water passage is equal to or less than the threshold value. Therefore, when the elapsed time from the stop of the internal combustion engine to the next start is a predetermined time or more, there is a possibility that the heat storage capsules are locally concentrated in the cooling water passage. According to the above configuration, when the internal combustion engine is started after a lapse of a predetermined time after the internal combustion engine is stopped, the flow rate of the cooling water flowing through the cooling water passage is forcibly made larger than the threshold value. It is possible to suppress the heat storage capsule from being locally concentrated in the water passage. As a result, it is possible to realize a state in which the heat storage capsules are uniformly dispersed in the cooling water passage in a short period after starting, and it is possible to suppress a decrease in cooling performance and reliability of the cooling device. If a water pump that can be driven regardless of the operating state of the internal combustion engine is provided, the water pump that is stopped when the internal combustion engine is stopped is operated when a predetermined time has elapsed since the stop of the internal combustion engine. May be.

  According to the present invention, in a cooling device for an internal combustion engine that uses variable specific heat cooling water in which a specific heat is larger in a predetermined temperature range than a specific heat outside the predetermined temperature range, a decrease in cooling performance and reliability is suppressed. can do.

It is a figure which shows schematic structure of the cooling device of the internal combustion engine which concerns on an Example. It is the figure which showed the relationship between cooling water temperature and the specific heat of cooling water. It is the flowchart which showed the control flow of the water pump concerning an Example. It is the flowchart which showed the control flow of the water pump concerning an Example. It is the flowchart which showed the control flow of the water pump concerning an Example.

  Hereinafter, specific embodiments of a cooling device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of a cooling device for an internal combustion engine according to the present embodiment. An internal combustion engine 1 shown in FIG. 1 is a water-cooled internal combustion engine.

  A water jacket 2 for circulating cooling water is formed inside the internal combustion engine 1. The internal combustion engine 1 is connected to a first cooling water passage 11 and a second cooling water passage 12. A radiator 13 and a bypass passage 14 are connected to the first cooling water passage 11 and the second cooling water passage 12.

  The first cooling water passage 11 connects the outlet side of the water jacket 2 and the inlet side of the radiator 13. That is, the first cooling water passage 11 is a passage for discharging cooling water from the water jacket 2. The second cooling water passage 12 connects the outlet side of the radiator 13 and the inlet side of the water jacket 2. That is, the second cooling water passage 12 is a passage for supplying cooling water to the water jacket 2.

  A water pump 3 that discharges cooling water from the second cooling water passage 12 side to the water jacket 2 side is provided at a connection portion between the second cooling water passage 12 and the water jacket 2.

  The bypass passage 14 bypasses the radiator 13 by connecting the first cooling water passage 11 and the second cooling water passage 12.

  Further, an electronically controlled thermostat 15 is provided in the second cooling water passage 12 closer to the radiator 13 than the connecting portion between the second cooling water passage 12 and the bypass passage 14. The opening degree of the thermostat 15 is adjusted according to a signal from the ECU 30 described later. The amount of cooling water supplied to the radiator 13 is adjusted by controlling the opening degree of the thermostat 15.

  When the thermostat 15 is closed, the cooling water flowing out from the water jacket 2 to the first cooling water passage 11 is sent to the water jacket 2 again via the bypass passage 14. By such cooling water circulation, the cooling water is gradually warmed, and warming up of the internal combustion engine 1 is promoted.

  Further, when the thermostat 15 is open, the cooling water is circulated through the radiator 13 and the bypass passage 14. Regardless of the state of the thermostat 15, the cooling water circulates in parts other than the radiator 13 and the bypass passage 14, but these parts are omitted in FIG.

  The water pump 3 adjusts the flow rate of the cooling water to be discharged, whereby the cooling water flowing through the cooling water passage including the first cooling water passage 11, the second cooling water passage 12, the radiator 13, the bypass passage 14, and the water jacket 2. It is a flow rate adjusting means for adjusting the flow rate.

  A water temperature at which the temperature of the cooling water flowing into the water jacket 2 (hereinafter also referred to as inlet side temperature) is measured in the second cooling water passage 12 between the connection portion of the water jacket 2 and the connection portion of the bypass passage 14. A sensor 32 is attached.

  The internal combustion engine 1 configured as described above is provided with an ECU 30 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 30 controls the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the driver's request.

  In addition to the above sensors, the ECU 30 includes an accelerator opening sensor 33 that outputs an electric signal corresponding to the accelerator opening to detect the engine load, and a crank position sensor 34 that detects the engine speed via electric wiring. It is connected. And the output signal of these sensors is input into ECU30, and ECU30 acquires the information which shows the driving | running state of an internal combustion engine. On the other hand, the thermostat 15 and the water pump 3 are connected to the ECU 30 via electric wiring, and the ECU 30 controls the opening and closing of the thermostat 15 and the flow rate of the cooling water discharged from the water pump 3.

  Here, the specific heat of the cooling water according to the present embodiment changes at a predetermined temperature or temperature range (collectively referred to as “temperature region”). Cooling water contains a substance (latent heat storage material) that undergoes a phase transition from solid to liquid, from liquid to solid, from liquid to gas, from gas to liquid, from solid to gas, or from gas to solid at a specified temperature range. A small heat storage capsule (for example, a particle size of 20 μm). For example, when a predetermined temperature range is reached in the process of increasing the temperature of the cooling water, the latent heat storage material included in the cooling water undergoes a phase transition (for example, changes from a solid to a liquid), and at this time, heat is absorbed from the surroundings. On the other hand, when the temperature of the cooling water reaches a predetermined temperature range, the latent heat storage material contained in the cooling water undergoes a phase transition (for example, changes from liquid to solid), and at this time, heat is released around.

  In the temperature range determined by the phase transition temperature of the latent heat storage material enclosed in the heat storage capsule or the temperature at which the phase transition starts and the temperature at which the phase transition ends, heat transfer to the cooling water is spent for the phase transition of the latent heat storage material. For this reason, the temperature of the cooling water is substantially constant. That is, the apparent specific heat of the cooling water is larger in this temperature range than the specific heat in other temperature ranges. Thus, in the temperature range where the latent heat storage material undergoes phase transition, the specific heat of the cooling water is larger than the other temperature ranges. If a plurality of types of heat storage capsules containing latent heat storage materials that undergo phase transition at different temperatures are contained in the cooling water, a plurality of temperature regions in which specific heat is increased can be set.

Here, FIG. 2 is a diagram showing the relationship between the cooling water temperature and the specific heat of the cooling water. As shown in FIG. 2, the specific heat is higher at the temperature in the temperature range T0 than at other temperatures. In the predetermined temperature range T0, even if the cooling water temperature is in the middle of rising or falling, it is once constant in the predetermined temperature range T0. The cooling water includes a heat storage capsule in which a phase transition temperature or a substance (latent heat storage material) whose temperature range from the start temperature to the end temperature of the phase transition is the temperature range T0 is enclosed. In FIG. 2, the predetermined temperature range T0 is shown as a temperature range having a certain width, but when the phase transition temperature of the latent heat storage material is a specific temperature, the predetermined temperature range T0 has no width. In FIG. 2, since the specific heat of the cooling water is low at a temperature other than the temperature range T0, the temperature of the cooling water changes rapidly with respect to heat input and output at a temperature other than the temperature range T0, while the temperature of the cooling water is a predetermined temperature. When the temperature is in the region T0, the temperature change of the cooling water becomes slow with respect to heat input and output. Therefore, when the temperature of the cooling water is set to a temperature other than the predetermined temperature range T0 during warm-up, the temperature of the cooling water can be quickly increased to improve fuel efficiency, and a large amount of heat is generated in the predetermined temperature range T0. Since the temperature of the cooling water can be maintained even if it is transferred, overheat resistance can be improved.

  In general, the specific heat of a substance is temperature-dependent, and the specific heat may change as the temperature changes, but the specific heat in the predetermined temperature range described above is larger than the specific heat in a temperature other than the predetermined temperature range. The temperature change of the specific heat is due to the phase transition of the latent heat storage material contained in the cooling water, and is different from the general temperature change of the specific heat which is not due to the phase transition of the contained material.

  In the cooling device according to the present embodiment, when the state where the flow rate of the cooling water in at least a part of the cooling water passage is equal to or lower than the predetermined threshold continues for a predetermined time or longer, the ECU 30 at least cools the cooling water in the part of the cooling water passage. The output of the water pump 3 is increased so that the flow rate becomes larger than the threshold value. The predetermined threshold value and the predetermined time are determined in advance based on the lower limit value of the flow rate of the cooling water and the upper limit value of the duration time of the flow rate so that the heat storage capsules are not locally concentrated in the cooling water passage. That is, if the flow rate of the cooling water flowing through the cooling water passage is larger than the threshold value, the heat storage capsules are prevented from being locally concentrated in the cooling water passage regardless of the duration of the flow rate state.

  When the state where the flow rate of the cooling water is equal to or lower than the predetermined threshold value continues for a predetermined time or longer, the flow rate of the cooling water is forcibly made larger than the threshold value by the control of the water pump 3 described above. The capsules are uniformly dispersed. Therefore, local accumulation of the heat storage capsules in the cooling water passage can be suppressed.

  In this embodiment, the ECU 30 acquires the flow rate of the cooling water discharged from the water pump 3, and based on the acquired history of the flow rate of the cooling water, whether or not the state where the flow rate is equal to or lower than the threshold value continues for a predetermined time or more. Make a decision.

  FIG. 3 is a flowchart showing a control flow of the water pump 3 according to the present embodiment. This routine is executed every predetermined time. In this embodiment, the ECU 30 that processes the flow shown in FIG. 3 corresponds to the control means in the present invention.

  In step S101, the ECU 30 detects the operating state of the internal combustion engine 1. Here, the ECU 30 detects the engine load based on the signal input from the accelerator opening sensor 33, detects the engine speed based on the signal input from the crank position sensor 34, and the signal input from the water temperature sensor 32. The cooling water temperature is detected based on Further, the ECU 30 acquires information on the flow rate at which the water pump 3 discharges the cooling water.

  In step S102, the ECU 30 determines whether the flow rate of the cooling water detected in step S101 is equal to or less than a threshold value. When the detected flow rate of the cooling water is equal to or lower than the threshold value, the ECU 30 proceeds to step S103, and when the detected flow rate of the cooling water is larger than the threshold value, the process of this flowchart is temporarily ended.

In step S103, the ECU 30 determines whether the state in which the detected coolant flow rate is equal to or less than the threshold value has continued for a predetermined time or more. For example, after it is determined in step S102 that the flow rate of the cooling water is equal to or lower than the threshold value, the ECU 30 intermittently detects the flow rate of the cooling water at predetermined intervals, and from the flow rate that is initially determined to be equal to or lower than the threshold value. When the state where the amount of change is within a certain range continues for a predetermined time or more, an affirmative determination is made in step S103. If it is determined in step S103 that the state where the flow rate is equal to or less than the threshold value has continued for a predetermined time or longer, the ECU 30 proceeds to step S104, and otherwise, the process of this flowchart is temporarily terminated.

  In step S104, the ECU 30 increases the output of the water pump 3 so that the flow rate of the cooling water becomes larger than the threshold value.

  Since ECU30 can perform the above process, it can suppress that a thermal storage capsule is crowded locally in a cooling water channel | path, and can suppress the cooling performance and reliability fall of a cooling device.

  Here, even when the water pump 3 discharges the cooling water at a flow rate larger than the threshold value, the cooling water remains in the radiator 13 when the thermostat 15 is closed. The flow rate of the cooling water in the radiator 13 which is a part of the passage is equal to or less than a threshold value (substantially zero). In the present embodiment, even when at least a part of the cooling water passage is in a state where the flow rate of the cooling water is equal to or lower than the threshold value for a predetermined time or longer, the flow rate of the cooling water in the part of the cooling water passage is larger than the threshold value. Perform such control. In the case of the radiator 13, when the state in which the thermostat 15 is closed continues for a predetermined time or longer, the thermostat 15 is forcibly opened, and the cooling water discharged by increasing the output of the water pump 3 is discharged. Increase flow rate above threshold. Thereby, it can suppress that the heat storage capsule will be in the state where it is crowded locally in the radiator 13.

  FIG. 4 is a flowchart showing a control flow of the water pump 3 described above. This routine is executed every predetermined time. In this embodiment, the ECU 30 that processes the flow shown in FIG. 4 corresponds to the control means in the present invention.

  In step S201, the ECU 30 detects the operating state of the internal combustion engine 1. The processing content of this step is the same as the processing of step S101 described above, but here, the ECU 30 acquires information on the open / close state of the thermostat 15 in particular.

  In step S202, the ECU 30 determines whether or not the thermostat 15 is in a valve-closed state based on the information on the open / close state of the thermostat detected in step S201. When the thermostat 15 is in the valve closing state, the ECU 30 proceeds to step S203, and when the thermostat 15 is in the valve opening state, the processing of this flowchart is once ended.

  In step S203, the ECU 30 determines whether the thermostat 15 has been closed for a predetermined time or longer. For example, after it is determined in step S202 that the thermostat 15 is in the closed state, the ECU 30 intermittently detects the open / closed state of the thermostat 15 at a predetermined interval, and the determination that the valve is in the closed state is not less than a predetermined time. If it continues, an affirmative determination is made in step S203. In step S203, when it is determined that the closed state of the thermostat 15 has continued for a predetermined time or longer, the ECU 30 proceeds to step S204, and otherwise, the process of this flowchart is temporarily ended.

  In step S204, the ECU 30 opens the thermostat 15, and in subsequent step S205, the output of the water pump 3 is increased so that the flow rate of the cooling water flowing through the radiator 13 becomes larger than the threshold value.

Since the ECU 30 executes the above processing, it is possible to suppress the heat storage capsules from being concentrated in the radiator 13 in particular, so that it is possible to suppress a decrease in cooling performance and reliability of the cooling device.

  When the water pump 3 is also stopped while the internal combustion engine 1 is stopped, the cooling water stays in the entire cooling water passage, and the flow rate of the cooling water flowing through the cooling water passage is equal to or less than the threshold value. In this embodiment, when the internal combustion engine is started after a predetermined time has elapsed after the internal combustion engine is stopped, the water pump 3 is set so that the flow rate of the cooling water in the cooling water passage becomes larger than the threshold value for a certain period after the start. To control. At this time, depending on the warm-up state, the thermostat 15 may be opened so that the flow rate of the cooling water in the radiator 13 is also larger than the threshold value. For example, in a vehicle that performs idling stop, when the internal combustion engine is already warmed up when the internal combustion engine is restarted, the cooling water may be circulated through the radiator 13 as well. On the other hand, at the time of cold start, priority may be given to completion of the early warm-up so that the cooling water is not circulated to the radiator 13. In this case, the thermostat 15 may be opened after the warm-up is completed, and the cooling water may be circulated at a flow rate larger than usual so that the heat storage capsules are not densely formed in the radiator 13.

  FIG. 5 is a flowchart showing a control flow of the water pump 3 described above. This routine is executed every predetermined time. In this embodiment, the ECU 30 that processes the flow shown in FIG. 5 corresponds to the control means in the present invention.

  When it is detected in step S301 that the internal combustion engine 1 has been started, in the subsequent step S302, the ECU 30 determines whether or not the stop state of the internal combustion engine 1 has continued for a predetermined time or more. For example, in the vehicle that performs idling stop, when the engine automatic stop at the time of idling is executed, the ECU 30 counts the elapsed time since the engine automatic stop is performed, and information on the elapsed time counted at the restart By reading, the duration of the engine stop state is acquired. If the engine is not stopped due to idling stop control, such as when the driver turns off the ignition switch, the processing for counting the duration of the engine stop state and the processing for acquiring the duration at the next engine start are not performed. You may do it. If it is determined in step S302 that the engine stop state has continued for a predetermined time or more, the ECU 30 proceeds to step S303, and otherwise the process of this flowchart is temporarily terminated.

  In step S303, the ECU 30 determines whether the internal combustion engine 1 has been warmed up. For example, the ECU 30 determines that the warm-up has been completed when the coolant temperature acquired from the water temperature sensor 32 is equal to or higher than a predetermined threshold. If it is determined in step S303 that the warm-up of the internal combustion engine 1 has been completed, the ECU 30 proceeds to step S304 and opens the thermostat 15. On the other hand, if it is determined in step S303 that the warm-up of the internal combustion engine 1 has not been completed, the ECU 30 proceeds to step S305 and closes the thermostat 15. After executing the process of step S304 or step S305, the ECU 30 proceeds to step S306.

  In step S306, the ECU 30 increases the output of the water pump 3 so that the flow rate of the cooling water becomes larger than the threshold value.

  By executing the above processing, the ECU 30 can suppress local accumulation of the heat storage capsules in the cooling water passage immediately after the internal combustion engine 1 is started, so that the cooling performance and reliability of the cooling device of the cooling device are deteriorated. Can be suppressed.

As described above, according to the present embodiment, the heat storage capsule containing the latent heat storage material that undergoes phase transition in the predetermined temperature range within the temperature range that the cooling water can take is contained in the predetermined temperature range. In the cooling device for an internal combustion engine that uses the cooling water having a specific heat larger than the specific heat outside the predetermined temperature range as a heat medium, it is possible to suppress the heat storage capsules from being locally concentrated in the cooling water passage. It becomes possible to suppress a decrease in cooling performance and reliability. The embodiments described above can be combined as much as possible without departing from the scope of the present invention.

1 Internal combustion engine 2 Water jacket 3 Water pump 11 First cooling water passage 12 Second cooling water passage 13 Radiator 14 Bypass passage 15 Thermostat 30 ECU
32 Water temperature sensor 33 Accelerator opening sensor 34 Crank position sensor

Claims (3)

By containing a heat storage capsule enclosing therein a latent heat storage material that undergoes phase transition in a predetermined temperature range within which cooling water can be taken, the specific heat in the predetermined temperature range is higher than the specific heat in other than the predetermined temperature range. A cooling device for an internal combustion engine that uses cooling water having a large value as a heat medium,
A cooling water passage through which cooling water flows;
Flow rate adjusting means capable of adjusting the flow rate of cooling water flowing through the cooling water passage;
When the state where the flow rate of the cooling water in at least a part of the cooling water passage is equal to or less than a predetermined threshold value continues for a predetermined time or longer, the flow rate adjusting means so that the flow rate of the cooling water in at least the part becomes larger than the threshold value. Control means for controlling
A cooling apparatus for an internal combustion engine. A radiator provided in the cooling water passage to remove heat from the cooling water;
A bypass passage for bypassing the radiator;
A thermostat that shuts off the flow of the cooling water to the radiator when closed and allows the cooling water to flow through the bypass passage, and at least opens the cooling water to the radiator and opens and closes regardless of the temperature of the cooling water; ,
With
The control means controls the flow rate adjusting means so that the thermostat is opened and the flow rate of cooling water in the radiator becomes larger than a threshold value when the state where the thermostat is closed continues for a predetermined time or more. Item 2. The cooling apparatus for an internal combustion engine according to Item 1.   The control means adjusts the flow rate so that the flow rate of the cooling water flowing through the cooling water passage becomes larger than the threshold when the internal combustion engine starts after the predetermined time or more has elapsed after the internal combustion engine is stopped. The cooling device for an internal combustion engine according to claim 1 or 2, which controls the means.

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