JP2008223725A - Cooling device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure recovered heat quantity by an exhaust gas heat recovery apparatus while preventing hunting action of an exhaust control valve. <P>SOLUTION: The exhaust control valve 160 for changing over execution/stop of exhaust gas heat recovery by the exhaust gas heat recovery apparatus 150 is driven to open and close by a heat sensing actuator 300. The heat sensing actuator 300 is provided in an auxiliary cooling water pipe 530. The auxiliary cooling water pipe 530 is provided to restrict or shut off flow of circulated cooling water when a thermostat 220 is closed (engine cold time), and to make the circulated cooling water flow when the thermostat 220 opens (engine valve open time). Consequently, since the heat sensing actuator 300 opens and closes with interlocking with the thermostat 220, exhaust gas heat recovery can be executed through engine cold time without hunting of the exhaust control valve 160 with responding to fluctuation of cooling water temperature near an engine outlet corresponding to engine load. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cooling device for an internal combustion engine, and more particularly, to a cooling device for an internal combustion engine configured to be able to exchange heat with an exhaust heat recovery unit provided in an exhaust pipe.

  2. Description of the Related Art Conventionally, a configuration in which an exhaust heat recovery device is incorporated in an engine cooling system in order to use the exhaust heat of an internal combustion engine in a heater (a heater core using engine cooling water as a heating source) is known (for example, Patent Literature 1 and 2).

  Patent Document 1 (Japanese Patent Laid-Open No. 2006-283711) discloses an exhaust heat recovery passage for recovering heat from exhaust gas of an internal combustion engine by an exhaust heat recovery device, and an exhaust bypass passage that bypasses the exhaust heat recovery passage. An exhaust heat recovery device and a control method therefor are disclosed in which a flow rate adjusting valve for adjusting a flow rate ratio of exhaust gas flowing through the exhaust heat recovery passage and the exhaust bypass passage is provided for the exhaust pipe of the internal combustion engine branched into .

  In Patent Document 1, the opening degree of the flow rate adjustment valve is variably controlled in accordance with the temperature of the cooling water and the exhaust gas flow rate determined from the operating state of the internal combustion engine or a substance flow rate correlated therewith. As a result, the exhaust heat recovery device according to Patent Document 1 can improve the heating performance by using the exhaust heat without deteriorating the fuel efficiency and exhaust emission of the internal combustion engine.

  In Patent Document 2 (Japanese Utility Model Publication No. 3-4566), when the heater fan is driven, when the engine coolant temperature is equal to or lower than a predetermined value and the heater strengthening switch is turned on, the exhaust provided with an exhaust heat exchanger is disclosed. There is disclosed an exhaust heat utilization heating device for an automobile provided with an actuator that operates so that a pipe is open and a bypass exhaust pipe is closed.

Further, Patent Document 3 (Japanese Patent Laid-Open No. 2006-250524) discloses a multi-tube heat recovery device capable of recovering heat from exhaust gas of an internal combustion engine, penetrating through an annular flow path and a center flowing during heat exchange. A configuration in which the bypass channel is selectively switched by a valve body that opens and closes according to the exhaust gas pressure is disclosed.
JP 2006-283711 A No. 3-4566 JP 2006-250524 A

  About the valve for controlling execution and stop of exhaust heat recovery indicated by patent documents 1-3, the endurance may fall by hunting which repeats opening and closing frequently in a short time.

  However, in the exhaust heat recovery apparatus disclosed in Patent Document 1, the flow rate adjustment valve that controls execution / stop of exhaust heat recovery is opened and closed according to the engine outlet water temperature. Since the engine outlet water temperature fluctuates according to the engine operating condition (load condition), in order to prevent the hunting operation of the flow rate adjusting valve, the threshold temperature for opening and closing the flow rate adjusting valve is provided in an area where hunting does not occur. It will be necessary. As a result, it may be difficult to ensure the heat recovery execution period.

  Also in Patent Document 2, the actuator that operates to open and close the exhaust pipe in the exhaust heat exchanger operates according to a water temperature switch provided in the vicinity of the engine outlet. Therefore, the same problem as in Patent Document 1 may occur. is there.

  In addition, the valve element disposed in the multi-tube heat recovery device disclosed in Patent Document 3 has a structure that opens and closes according to the exhaust gas pressure or the exhaust flow rate of the internal combustion engine, and thus is frequently opened and closed. Probability is high. Although it is described that auxiliary control according to the temperature of the exhaust gas or the refrigerant may be added to the control of the valve body (for example, the description in paragraph 0017), the control according to the temperature of any part should be performed. There is no specific reference to kika.

  The present invention has been made to solve such problems, and an object of the present invention is to control the exhaust heat recovery device and the execution and stop of exhaust heat recovery in the exhaust heat recovery device. An internal combustion engine cooling apparatus provided with this exhaust control valve provides a configuration capable of ensuring the amount of heat recovered by the exhaust heat recovery device while preventing the hunting operation of the exhaust control valve.

  An internal combustion engine cooling apparatus according to the present invention includes a refrigerant pump for circulating a refrigerant of an internal combustion engine, a refrigerant pipe, a heat dissipation mechanism, a load device, a heat sensitive valve, an exhaust heat recovery device, an exhaust control valve, An auxiliary refrigerant path and a thermal actuator are included. The refrigerant pipe is arranged so that the first and second refrigerant circulation paths are formed in parallel by driving the refrigerant pump. The heat dissipation mechanism is disposed on the first refrigerant circulation path to cool the refrigerant. The load device is disposed in the second refrigerant circulation path, and operates using the amount of heat of the refrigerant. The thermal valve is arranged on the first refrigerant circulation path, and is configured to open in response to the refrigerant temperature at the arrangement site being equal to or higher than a predetermined temperature. The exhaust heat recovery device is provided in the exhaust pipe of the internal combustion engine. The exhaust control valve has a first exhaust path configured to be able to exchange heat with the refrigerant by an exhaust heat recovery device for the exhaust gas from the internal combustion engine, and a second exhaust path that bypasses the first exhaust path. It is configured to control the flow rate ratio between. The auxiliary refrigerant path is arranged so that the flow of the refrigerant is restricted when the thermal valve is closed, while the refrigerant flows according to the driving of the refrigerant pump when the thermal valve is opened. The thermal actuator is arranged in the auxiliary refrigerant path, and is configured to operate according to the refrigerant temperature of the arrangement site to open and close the exhaust control valve. The thermal actuator sets the threshold temperature to the refrigerant temperature corresponding to the refrigerant temperature when the refrigerant flows through the auxiliary refrigerant path by opening the thermal valve, and exhaust gas when the refrigerant temperature is equal to or lower than the threshold temperature. While mainly flowing through the first exhaust path, the exhaust control valve is driven so that the exhaust gas mainly flows through the second exhaust path when the refrigerant temperature is higher than the threshold temperature.

  Preferably, the heat-sensitive actuator drives the exhaust control valve so that the second exhaust path is closed in the exhaust heat recovery device when the refrigerant temperature is lower than the threshold value.

  According to the cooling apparatus for an internal combustion engine, when the heat sensitive valve is closed so that the refrigerant bypasses the heat dissipation mechanism (during warming up of the internal combustion engine), the refrigerant does not flow in the auxiliary refrigerant path and stays there. Therefore, the refrigerant temperature at the thermal actuator portion remains low regardless of the change in the refrigerant temperature caused by the change in the balance between the load of the internal combustion engine and the amount of heat used by the load device. On the other hand, when the temperature of the circulating refrigerant rises to such an extent that the thermal valve opens, the refrigerant temperature at the thermal actuator part rises in response to the circulating refrigerant flowing through the auxiliary refrigerant path. For this reason, exhaust heat recovery is performed in the cold while exhaust heat recovery is performed in the warm while the exhaust control valve is not hunted in response to fluctuations in the coolant temperature near the outlet of the internal combustion engine corresponding to the load of the internal combustion engine. The exhaust control valve is stably opened and closed to stop the operation. Accordingly, the exhaust heat recovery can be performed during the warm-up of the internal combustion engine, so that the refrigerant temperature can be raised at an early stage when it is cold. As a result, the warm-up time can be shortened and fuel consumption can be improved.

Preferably, the load device includes a heater using a refrigerant as a heating source.
With such a configuration, in the configuration in which the heater is provided in the second refrigerant circulation path where the refrigerant temperature rises due to heat exchange with the exhaust heat recovery device, the cooling water is recovered by exhaust heat recovery when the engine is cold. By raising the temperature of the vehicle at an early stage, particularly in the winter season, the heating performance can be rapidly exerted to improve the comfort in the passenger compartment.

  Preferably, the threshold temperature of the thermal actuator is set lower than the refrigerant temperature when the thermal valve opens.

  With such a configuration, the heat sensitive actuator can be reliably operated in conjunction with the opening of the heat sensitive valve to stop the exhaust heat recovery, so that the refrigerant temperature rises excessively due to the exhaust heat recovery. Can be prevented.

  Preferably, the first refrigerant circulation path passes through a first refrigerant path for bypassing a heat dissipation mechanism formed when the heat sensitive valve is closed and a heat dissipation mechanism formed when the heat sensitive valve is opened. 2 refrigerant paths. The auxiliary refrigerant path is arranged to connect between the second refrigerant circulation path and the second refrigerant path in the first refrigerant circulation path.

  Thus, in the configuration in which the bypass path of the heat dissipation mechanism is provided in the first refrigerant circulation path, the refrigerant path (second refrigerant path) other than the bypass path on the first refrigerant circulation path and the second refrigerant circulation path An auxiliary refrigerant path can be disposed between the two.

  Alternatively, preferably, in the second refrigerant circulation path, the refrigerant path in which the load device is arranged is provided so as to bypass the refrigerant path for heat exchange in the exhaust heat recovery device.

  According to the cooling apparatus for an internal combustion engine of the present invention, an exhaust heat recovery device and an exhaust control valve for controlling execution and stop of exhaust heat recovery in the exhaust heat recovery device are provided. The amount of heat recovered by the exhaust heat recovery device can be secured while preventing the hunting operation.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

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

  Referring to FIG. 1, engine 100 is an internal combustion engine provided with a cooling passage (not shown) made of a refrigerant. Since water is typically used as the refrigerant of engine 100, the refrigerant is hereinafter also referred to as engine cooling water or simply cooling water.

  The engine 100 is provided with a water pump 120 that is a “refrigerant pump” for circulating the refrigerant in the cooling device. Water pump 120 may be an electric pump or may be a mechanical pump driven by the rotational force of engine 100. The cooling water piping group 500 includes a cooling water circulation path 500 a for allowing cooling water output from the engine 100 to flow to the radiator 210 and a cooling water circulation path 500 b for allowing the heater 200 to flow by the operation of the water pump 120. It arrange | positions so that it may form in parallel.

  A thermostat 220 is provided in the cooling water circulation path 500a. The thermostat 220 is a “heat sensitive valve” that opens and closes according to the cooling water temperature of the arrangement site. In the cooling water circulation path 500a, when the thermostat 220 is closed (when the engine is cold), a cooling water path 515 is formed from the cooling water outlet of the engine 100 to the water pump 120 by bypassing the radiator 210 by the bypass pipe 510. Is done. On the other hand, when the cooling water temperature rises and the thermostat 220 opens (that is, when the engine is warm), the cooling water in the cooling water circulation path 500a passes through the radiator 210 from the cooling water outlet of the engine 100 without passing through the bypass pipe 510. It will circulate through the cooling water path 525 which passes and reaches the water pump 120. The radiator 210 has an air cooling mechanism (not shown), and cools the cooling water circulating through the cooling water circulation path 500a by heat exchange of the air cooling mechanism.

  That is, in the cooling water circulation path 500a, the cooling water circulates through the cooling water path 515 when the thermostat is closed (when cold), and the cooling water path 525 when the thermostat 220 is opened (when warm). The cooling water is configured to circulate.

  Another cooling water circulation path 500 b includes a cooling water path 505 that flows from the cooling water outlet of engine 100 through heater 200 and exhaust heat recovery device 150 to water pump 120. The heater 200 is provided as a heating heat exchanger, and performs heating using the cooling water flowing through the cooling water circulation path 500b as a heat source. That is, the cooling water circulates in the cooling water circulation path 500b by the operation of the water pump 120, so that air heated by heat exchange with the cooling water (hot water) is sent to the vehicle interior by a fan (not shown). Has been.

  The heater 200 is shown as a representative example of a “load device” that operates using the heat quantity of cooling water. In addition, a load device may be comprised by apparatuses other than the heater 200, and load devices other than the heater 200 may be further provided in the cooling water circulation path 500b.

  The exhaust heat recovery unit 150 is provided in the exhaust pipe 110 of the engine 100 so that exhaust heat recovery can be performed by exchanging heat between the cooling water flowing through the cooling water circulation path 500b and the exhaust gas from the engine 100. It is configured. The exhaust heat recovery device 150 is provided with an exhaust control valve 160 as a switching mechanism for executing or stopping exhaust heat recovery.

  Next, a schematic configuration of the exhaust heat recovery unit 150 and an exhaust path during execution / stop of exhaust heat recovery will be described with reference to FIGS. 2 and 3.

  Referring to FIG. 2, when exhaust control valve 160 is closed by thermal actuator 300, exhaust gas from engine 100 exchanges heat with refrigerant in cooling water passage 152 included in cooling water circulation passage 500b. Flow through possible heat recovery path 156. As a result, when the exhaust control valve 160 is closed, heat exchange is performed between the exhaust gas and the cooling water in the cooling water circulation path 500b, and the cooling water temperature can be quickly raised by heat recovery of the exhaust gas. Become.

  On the other hand, as shown in FIG. 3, when the exhaust control valve 160 is opened by the thermal actuator 300, the exhaust gas from the engine 100 flows through the bypass path 158 that bypasses the heat recovery path 156 shown in FIG. The At this time, since heat exchange between the exhaust gas and the cooling water is hardly performed, the heat recovery from the exhaust gas as shown in FIG. 2 is stopped.

  Referring to FIG. 1 again, auxiliary cooling water pipe 530 is provided to connect between cooling water circulation path 500b and cooling water path 525 on cooling water circulation path 500a. The thermal actuator 300 is provided on the cooling water path by the auxiliary cooling water pipe 530 and opens and closes the exhaust control valve 160 according to the cooling water temperature of the arrangement site. For example, the thermal actuator 300 can be configured by applying a thermostat or a shape memory alloy. The thermal actuator 300 closes the exhaust control valve 160 (executes heat recovery) when the cooling water temperature is lower than a predetermined threshold temperature, and opens the exhaust control valve 160 when the cooling water temperature is equal to or higher than the predetermined threshold temperature (heat Configured to stop collection).

  Even when the water pump 120 is driven when the thermostat 220 is closed, the cooling water stays in the auxiliary cooling water pipe 530 with the flow restricted. Therefore, the cooling water temperature in the auxiliary path 535, that is, the cooling water temperature at the location where the thermal actuator 300 is disposed remains low. Therefore, during the valve closing period of the thermostat 220 (when cold), the thermal actuator 300 closes the exhaust control valve 160 (FIG. 2), and exhaust heat recovery by the exhaust heat recovery device 150 is executed.

  On the other hand, when the temperature of the cooling water in the cooling water circulation path 500a rises and the thermostat 220 opens, the circulating cooling water flows through the auxiliary cooling water pipe 530 as the cooling water circulates through the cooling water path 525. Become. At this time, since the cooling water is warm water, the thermal actuator 300 opens the exhaust control valve 160 (FIG. 3). Thereby, the heat recovery in the exhaust heat recovery device 150 is stopped. As described above, heat recovery can be continuously performed until the thermostat 220 is opened, that is, until the engine warm-up is completed.

  Next, the execution and stop switching of exhaust heat recovery in the cooling apparatus for an internal combustion engine according to the embodiment of the present invention will be described with reference to FIGS.

  For comparison, FIG. 4 shows a waveform diagram when the exhaust control valve 160 is controlled to open and close in response to the cooling water temperature (engine outlet water temperature) Twe at the engine outlet as in Patent Document 1.

  Referring to FIG. 4, although the cooling water temperature is low at the start of engine operation (cold state), the engine outlet water temperature Twe rises due to heat generated by the operation of the engine and exhaust heat recovery b.

  However, the cooling water temperature decreases during a period in which the engine load decreases during idle operation and the amount of heat utilization from the cooling water by the heater 200 exceeds the engine heat generation amount. For this reason, the engine outlet water temperature Twe rises or falls corresponding to changes in the engine load. In particular, such temperature fluctuations are significant in an intermediate temperature range from cold to warm.

  For this reason, when the exhaust control valve 160 is controlled according to the engine outlet water temperature Twe, in order to avoid hunting of the exhaust control valve 160, the threshold temperature Tth # for switching the opening / closing is set to the intermediate temperature range described above. It is necessary to avoid it and set it relatively low.

  This substantially shortens the exhaust heat recovery period Trc when the engine is cold. That is, if the threshold temperature Tth # is set to a higher temperature side to secure the exhaust heat recovery period, the exhaust control valve 160 is frequently opened and closed, and depending on the situation, hunting may occur and the durability may be hindered. There is.

  In FIG. 5, the engine outlet water temperature Twe shown in FIG. 4 is indicated by a dotted line, and the water temperature Tw between the radiator 210 and the thermostat 220, that is, the cooling water temperature Tw in the auxiliary cooling water pipe 530 is further shown. As described above, the thermal actuator 300 opens and closes the exhaust control valve 160 according to the cooling water temperature Tw.

  While the thermostat 220 is closed (when the engine is cold), the cooling water stays in the auxiliary cooling water pipe 530 because the flow is restricted or stopped, and the auxiliary path 535 is disconnected from the cooling water circulation paths 500a and 500b. It is. For this reason, the cooling water temperature Tw is maintained at a low temperature.

  On the other hand, when the cooling water temperature of the cooling water path 515 that bypasses the radiator 210 in the cooling water circulation path 500a is equal to or higher than the threshold temperature Tth at which the thermostat opens, the cooling water circulation path 500a, The cooling water circulating in 500b flows through the auxiliary cooling water pipe 530. Thereby, the cooling water temperature Tw rises.

  In addition, once the thermostat 220 is opened, the auxiliary path 535 is cooled by closing the thermostat 220 again even if the cooling water temperature decreases due to heat utilization in a load device represented by the heater 200. The water circulation paths 500a and 500b are disconnected. At this time, since the cooling water temperature Tw is not affected by the heat utilization or the like, the temperature fluctuation is smaller than the engine outlet water temperature Twe.

  Thus, the cooling water temperature Tw is compared with the engine outlet water temperature Twe, the temperature fluctuation in the intermediate temperature region during the transition from the cold time to the warm time (while the thermostat 220 is closed), and The temperature fluctuation after opening the thermostat 220 is small. That is, the cooling water temperature Tw rapidly rises from the temperature when the engine is cold to the temperature when the engine is warm, and the temperature fluctuation after the rise is small and shows a stable temperature transition.

  Therefore, even if the threshold temperature Tth # is set higher than that in FIG. 4 by providing the thermal actuator 300 at the portion of the cooling water temperature Tw (auxiliary cooling water pipe 530) and driving the exhaust control valve 160 to open and close, Hunting is not generated in the control valve 160. Therefore, the exhaust heat recovery period Trc can be secured more than in the comparative example (FIG. 4).

  As a result, exhaust heat recovery can be performed throughout the engine warm-up without hunting the exhaust control valve in response to a change in the coolant temperature corresponding to the engine load. As a result, the coolant temperature can be raised early by exhaust heat recovery when the engine is cold, so that it is possible to shorten the warm-up time and improve fuel efficiency. Particularly in the winter season, the heating performance of the heater 200 can be quickly exhibited to improve the comfort in the passenger compartment.

  Further, as shown in FIG. 5, by setting the threshold temperature Tth # of the thermal actuator 300 to be lower than the threshold temperature Tth at which the thermostat opens, the thermal actuator 300 operates in conjunction with the opening of the thermostat 220. The exhaust heat recovery can be stopped by reliably opening the exhaust control valve 160. Thereby, it is possible to prevent the cooling water temperature from excessively rising due to exhaust heat recovery.

  In addition, although the cooling water was illustrated as a refrigerant | coolant in embodiment of this invention, the cooling medium is not restricted to water, It is also possible to use the optimal liquid or gas suitably.

  The location of the auxiliary cooling water pipe 530 where the thermal actuator 300 is provided is not limited to the illustration of FIG. That is, when the thermostat 220 is closed (when the engine is cold), the circulation of the circulating cooling water is interrupted or restricted, while the circulating cooling water (hot water) is allowed to flow when the thermostat 220 is opened. As long as it is configured, the auxiliary cooling water pipe 530 can be disposed at any location. For example, it can be provided at any position between the portion where the flow of the cooling water is blocked when the thermostat 220 on the cooling water circulation path 500a is closed and the portion on the cooling water circulation path 500b.

  Further, as shown in the modification of FIG. 6, it is possible to adopt a configuration in which the bypass pipe 510 is not disposed in the cooling water circulation path 500a. In this case, any part of the cooling water circulation path 500a and the cooling water circulation path 500b can be connected.

  As shown in the modification of FIG. 7, in the cooling water circulation path 500b, the refrigerant path for exchanging heat in the exhaust heat recovery device 150 is bypassed in the refrigerant path in which the heater 200 (load device) is arranged. It is also possible to provide it.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a block diagram showing an overall configuration of a cooling device for an internal combustion engine according to an embodiment of the present invention. It is a figure explaining the exhaust route at the time of exhaust heat recovery execution. It is a figure explaining the exhaust route at the time of exhaust heat recovery stop. It is a wave form diagram explaining switching of execution and stop of exhaust heat recovery shown as a comparative example. It is a wave form diagram explaining switching of execution and stop of exhaust heat recovery in a cooling device of an internal-combustion engine by an embodiment of the invention. It is a block diagram which shows the whole structure of the 1st modification of the cooling device of the internal combustion engine by embodiment of this invention. It is a block diagram which shows the whole structure of the 2nd modification of the cooling device of the internal combustion engine by embodiment of this invention.

Explanation of symbols

  100 Engine, 110 Exhaust pipe, 120 Water pump, 150 Exhaust heat recovery unit, 152 Cooling water path, 156 Heat recovery path, 158 Bypass path, 160 Exhaust control valve, 200 Heater, 210 Radiator, 220 Thermostat, 300 Thermal actuator, 500 Cooling Water piping group, 500a, 500b Cooling water circulation path, 510 Bypass piping, 505, 515, 525 Cooling water path, 530 Auxiliary cooling water piping, 535 Auxiliary path, Trc Exhaust heat recovery period, Tth threshold temperature (thermostat open / close), Tth # Threshold temperature (exhaust control valve open / close), Tw cooling water temperature (actuator location), Twe engine outlet water temperature.

Claims (6)

A refrigerant pump for circulating the refrigerant of the internal combustion engine;
Refrigerant piping arranged so that the first and second refrigerant circulation paths are formed in parallel by driving the refrigerant pump;
A heat dissipating mechanism for the refrigerant disposed in the first refrigerant circulation path;
A load device that is disposed in the second refrigerant circulation path and that operates using the amount of heat of the refrigerant;
A thermal valve that is arranged in the first refrigerant circulation path and opens in response to the refrigerant temperature of the arrangement part being equal to or higher than a predetermined temperature;
An exhaust heat recovery device provided in an exhaust pipe of the internal combustion engine;
Between exhaust gas from the internal combustion engine, a first exhaust path configured to be able to exchange heat with the refrigerant by the exhaust heat recovery device, and a second exhaust path that bypasses the first exhaust path. An exhaust control valve for controlling the flow rate ratio of
Auxiliary refrigerant disposed in a portion where the flow of the refrigerant is restricted when the heat sensitive valve is closed while the refrigerant flows according to the driving of the refrigerant pump when the heat sensitive valve is opened. Route,
A thermal actuator arranged in the auxiliary refrigerant path and operating according to the refrigerant temperature of the arrangement site to open and close the exhaust control valve;
The thermosensitive actuator sets a threshold temperature to the refrigerant temperature corresponding to a refrigerant temperature when the refrigerant flows through the auxiliary refrigerant path by opening the thermal valve, and the refrigerant temperature is equal to or lower than the threshold temperature. Sometimes the exhaust gas mainly flows through the first exhaust path, while the exhaust gas mainly flows through the second exhaust path when the refrigerant temperature is higher than the threshold temperature. An internal combustion engine cooling apparatus for driving the exhaust control valve.   2. The internal combustion engine according to claim 1, wherein when the refrigerant temperature is lower than the threshold temperature, the thermal actuator drives the exhaust control valve so that the second exhaust path is closed in the exhaust heat recovery unit. Cooling system.   The cooling device for an internal combustion engine according to claim 1, wherein the load device includes a heater using the refrigerant as a heat source.   The cooling device for an internal combustion engine according to claim 1, wherein the threshold temperature of the thermal actuator is set lower than a refrigerant temperature when the thermal valve opens. The first refrigerant circulation path passes through a first refrigerant path for bypassing the heat dissipation mechanism formed when the thermal valve is closed, and the heat dissipation mechanism formed when the thermal valve is opened. Including a second refrigerant path;
2. The internal combustion engine according to claim 1, wherein the auxiliary refrigerant path is disposed so as to connect between the second refrigerant circulation path and the second refrigerant path in the first refrigerant circulation path. Cooling system.   2. The cooling of the internal combustion engine according to claim 1, wherein in the second refrigerant circulation path, the refrigerant path in which the load device is arranged is provided so as to bypass a refrigerant path for exchanging heat in the exhaust heat recovery unit. apparatus.

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