JP2008051019A - Exhaust heat recovery device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device for an internal combustion engine, taking appropriate measures against an operation abnormality, by detecting the operation abnormality of a selector valve switching between heat exchange and restriction of the heat exchange in exhaust heat recovery equipment. <P>SOLUTION: The exhaust heat recovery device for an internal combustion engine is suitably utilized for performing heat exchange between cooling water and exhaust gas by using the exhaust heat recovery equipment. Concretely, in the device, passages flowing the exhaust gas therethrough are switched by using the selector valve so as to perform switching between the heat exchange and the restriction of heat exchange in the exhaust heat recovery equipment. The operation abnormality of the flow passage selector valve is detected based on a cooling water temperature or the like so as to perform a control responding to the operation abnormality. Therefore, malfunction in operation of the internal combustion engine caused by the operation abnormality or breaking of the exhaust heat recover equipment can be effectively suppressed, while properly detecting the operation abnormality of the flow passage selector valve. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery apparatus for an internal combustion engine that performs heat exchange between exhaust gas and cooling water.

  Conventionally, techniques for exchanging heat between exhaust gas and cooling water to recover exhaust heat have been proposed. For example, in Patent Document 1, in an exhaust heat recovery device that recovers exhaust heat from an internal combustion engine with cooling water, the cooling water is circulated by driving an electric pump immediately after the internal combustion engine is stopped, and an exhaust heat recovery portion A technique for preventing the boiling of cooling water at the factory is described.

JP-A-2-104952

  However, in the technique described in Patent Document 1 described above, exhaust heat is excessively recovered, the temperature of the cooling water increases, and the efficiency of the internal combustion engine decreases. By the way, there can be considered a method in which a mechanism for restricting heat exchange in the exhaust heat recovery unit is provided to suppress the excessive recovery of exhaust heat as described above. However, even when such a mechanism is used, if an abnormality occurs in the mechanism, malfunction of the internal combustion engine or destruction of the exhaust heat recovery device may occur.

  The present invention has been made to solve the above-described problems, and detects an abnormal operation of a switching valve that switches between heat exchange and heat exchange restriction in an exhaust heat recovery device, and prevents the abnormal operation. It is an object of the present invention to provide an exhaust heat recovery device for an internal combustion engine capable of taking appropriate measures.

  In one aspect of the present invention, an exhaust heat recovery unit that is disposed on an exhaust passage of an internal combustion engine and exchanges heat between cooling water passing through the interior and exhaust gas, and an electric pump that circulates the cooling water, An exhaust heat recovery device for an internal combustion engine having a flow path switching for controlling a flow rate of at least one of the exhaust gas and the cooling water passing through a location on an exhaust passage provided with the exhaust heat recovery device A valve, a flow path switching valve control means for controlling the flow path switching valve, an operation abnormality detection means for detecting an operational abnormality of the flow path switching valve, and the operation abnormality detection means for operating the flow path switching valve. An operation abnormality coping execution means for executing control for coping with the operation abnormality when an abnormality is detected.

  The exhaust heat recovery apparatus for an internal combustion engine is preferably used for exchanging heat between cooling water and exhaust gas using an exhaust heat recovery device. Specifically, the flow path switching valve (hereinafter also simply referred to as “switching valve”) is at least one of exhaust gas and cooling water passing through a location on the exhaust passage provided with the exhaust heat recovery device. The flow path switching valve control means controls the flow path switching valve. The operation abnormality detection means detects an operation abnormality of the flow path switching valve, and the operation abnormality countermeasure execution means controls to cope with the operation abnormality when the operation abnormality of the flow path switching valve occurs. Execute. Accordingly, it is possible to appropriately detect an operation abnormality of the flow path switching valve, and to suppress malfunction of the internal combustion engine, destruction of the exhaust heat recovery device, and the like due to the operation abnormality of the flow path switching valve.

  In one aspect of the exhaust heat recovery apparatus for an internal combustion engine, the flow path switching valve bypasses the first exhaust passage that passes through a location on the exhaust passage provided with the exhaust heat recovery device, and the location. The second exhaust passage and the flow rate of exhaust gas flowing through the second exhaust passage can be adjusted.

  In another aspect of the exhaust heat recovery apparatus for an internal combustion engine, the operation abnormality detection means is based on a relationship between an operation command for the flow path switching valve and a temperature of the cooling water detected by a water temperature sensor. An abnormal operation of the flow path switching valve is detected.

  In this aspect, the operation abnormality detection means compares, for example, the temperature of the cooling water that is assumed when the flow path switching valve appropriately operates according to the operation command and the temperature of the cooling water acquired from the sensor. Thus, an abnormal operation of the flow path switching valve is detected. Thereby, based on the temperature detected by the water temperature sensor, an abnormal operation of the flow path switching valve can be detected appropriately.

  Preferably, the exhaust heat recovery apparatus for an internal combustion engine includes a first water temperature sensor that detects a temperature of cooling water flowing downstream of the exhaust heat recovery device, and the operation abnormality detection means includes the first abnormality detection unit. An abnormal operation of the flow path switching valve is detected based on the temperature detected by the water temperature sensor.

  In this case, the operation abnormality detection means is configured such that the flow rate of the exhaust gas flowing into the first exhaust passage is suppressed so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. When the flow path switching valve is controlled, the temperature of the cooling water is estimated based on at least the operating state of the internal combustion engine, and the temperature detected by the first water temperature sensor is a predetermined value. When the temperature exceeds the above or when the temperature detected by the first water temperature sensor does not decrease, it is determined that an abnormality has occurred in the operation of the flow path switching valve for restricting heat exchange by the exhaust heat recovery device. be able to.

  In the exhaust heat recovery apparatus for an internal combustion engine, preferably, the exhaust heat recovery device further includes a second water temperature sensor for detecting a temperature of the cooling water flowing upstream of the exhaust heat recovery device, An abnormal operation of the flow path switching valve is detected based on the temperature detected by the first water temperature sensor and the temperature detected by the second water temperature sensor.

  In this case, the operation abnormality detection means is configured such that the flow rate of the exhaust gas flowing into the first exhaust passage is suppressed so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. If the difference between the temperature detected by the first water temperature sensor and the temperature detected by the second water temperature sensor is greater than or equal to a predetermined value when the flow path switching valve is controlled, the exhaust heat recovery device It can be determined that an abnormality has occurred in the operation of the flow path switching valve for limiting heat exchange.

  In another aspect of the exhaust heat recovery apparatus for an internal combustion engine, the operation abnormality detection means may be configured such that the flow path switching valve is based on a relationship between an operation command for the flow path switching valve and a water pressure of the cooling water. Detects abnormal operation.

  In this aspect, the operation abnormality detection means compares, for example, the coolant pressure assumed when the flow path switching valve appropriately operates according to the operation command and the coolant pressure acquired from the sensor. Thus, an abnormal operation of the flow path switching valve is detected. Thereby, based on the water pressure detected by the water pressure sensor, an abnormal operation of the flow path switching valve can be detected appropriately.

  Preferably, the exhaust heat recovery apparatus for an internal combustion engine includes a first water pressure sensor that detects a water pressure of cooling water flowing downstream of the exhaust heat recovery device, and the operation abnormality detection means includes the first abnormality detection unit. Based on the water pressure detected by the water pressure sensor, an abnormal operation of the flow path switching valve is detected.

  In this case, the operation abnormality detection means is configured such that the flow rate of the exhaust gas flowing into the first exhaust passage is suppressed so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. When the flow path switching valve is controlled, the water pressure of the cooling water is estimated based on at least the operating state of the internal combustion engine, and the water pressure detected by the first water pressure sensor is set to a predetermined value. When the pressure exceeds the above or when the water pressure detected by the first water pressure sensor does not decrease, it is determined that an abnormality has occurred in the operation of the flow path switching valve for restricting heat exchange by the exhaust heat recovery device. be able to.

  Preferably, the exhaust heat recovery apparatus for an internal combustion engine further includes a second water pressure sensor for detecting a water pressure of cooling water flowing upstream of the exhaust heat recovery device, and the operation abnormality detection means includes the first abnormality detector. The abnormal operation of the flow path switching valve is detected based on the water pressure detected by the water pressure sensor and the water pressure detected by the second water pressure sensor.

  In this case, the operation abnormality detection means is configured such that the flow rate of the exhaust gas flowing into the first exhaust passage is suppressed so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. If the difference between the water pressure detected by the first water pressure sensor and the water pressure detected by the second water pressure sensor is greater than or equal to a predetermined value when the flow path switching valve is controlled, the exhaust heat recovery device It can be determined that an abnormality has occurred in the operation of the flow path switching valve for limiting heat exchange.

  In another aspect of the exhaust heat recovery apparatus for an internal combustion engine described above, the operation abnormality countermeasure execution means has an abnormality in the operation of the flow path switching valve for the operation abnormality detection means to restrict heat exchange. When it is determined that the electric pump is present, control is performed to increase the flow rate of the electric pump. Thereby, when the operation abnormality of a flow-path switching valve generate | occur | produces, the raise of a cooling water temperature can be suppressed appropriately. Therefore, it is possible to suppress overheating of the internal combustion engine.

  In another aspect of the exhaust heat recovery apparatus for an internal combustion engine, the operation abnormality countermeasure execution means performs control to increase the flow rate of the electric pump, and then, when a predetermined condition is satisfied, the cooling water is supplied to the heater core. The control is further performed to circulate the air and promote heat dissipation.

  In this mode, the operation abnormality countermeasure executing means promotes heat dissipation by circulating the cooling water to the heater core, for example, when the cooling water temperature is relatively high, even though control for increasing the flow rate of the electric pump is performed. Further control is performed. Thereby, when the operation abnormality of a flow-path switching valve generate | occur | produces, it becomes possible to suppress the raise of a cooling water temperature effectively, and to suppress the overheating of an internal combustion engine reliably.

  Preferably, the internal combustion engine is mounted on a hybrid vehicle, and includes means for setting the internal combustion engine to a predetermined operation state when the operation abnormality detection unit detects the operation abnormality of the flow path switching valve.

  More preferably, there is provided means for setting the electric pump to a predetermined driving state when detecting the operation abnormality of the flow path switching valve by the operation abnormality detecting means.

  In another aspect of the exhaust heat recovery apparatus for an internal combustion engine described above, there is provided means for detecting an abnormality of the water temperature sensor in a state where the electric pump is stopped. When the electric pump is stopped in this way, a change may occur in the actual cooling water temperature, so that the abnormality of the water temperature sensor can be detected based on whether or not this change has been detected.

  Preferably, the exhaust heat recovery apparatus for an internal combustion engine includes means for prohibiting detection of an operation abnormality of the flow path switching valve by the operation abnormality detection means when an abnormality of the water temperature sensor is detected. By prohibiting the detection of the operation abnormality for the flow path switching valve in this way, the detection accuracy of the operation abnormality can be ensured.

  In another aspect of the exhaust heat recovery apparatus for an internal combustion engine, when the abnormality of the water temperature sensor is not detected, a change in the temperature of the cooling water is detected by the water temperature sensor after the internal combustion engine is started. The thermostat is provided with means for determining that the thermostat is abnormal. In this case, when it is determined that the water temperature sensor is normal, if a change in the cooling water temperature is detected after the electric pump is stopped, it can be determined that the thermostat has an open failure or the like.

  Preferably, in the exhaust heat recovery apparatus for an internal combustion engine, the flow path switching valve control means is configured to change the flow path for limiting heat exchange by the exhaust heat recovery device when an abnormality of the thermostat is detected. Release the valve. That is, the switching valve can be controlled so that the exhaust heat recovery is performed in the exhaust heat recovery unit. When the thermostat has an open failure, etc., the cooling water is cooled by the radiator and the temperature of the internal combustion engine tends to decrease, but as described above, the restriction of heat exchange is canceled and exhaust heat is recovered. And the fall of cooling water temperature can be suppressed. Therefore, it is possible to appropriately suppress the overcooling of the internal combustion engine due to the abnormality of the thermostat.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Configuration of cooling system]
FIG. 1 is a diagram showing a schematic configuration of a cooling system 100 to which an exhaust heat recovery apparatus according to an embodiment of the present invention is applied. In FIG. 1, solid arrows indicate the flow of cooling water, and broken arrows indicate input / output of signals. A solid line indicated by a bold line indicates a passage (cooling water passage) through which the cooling water flows.

  The cooling system 100 according to the present embodiment cools the engine 1 using cooling water, collects exhaust heat by exchanging heat between the cooling water and the exhaust gas, and warms the engine 1. This system is used as a heat source for machines and heaters. In this case, the cooling water cools and warms up the engine 1 by passing through the cooling water passages 7a, 7b, and 7c. The exhaust heat recovery device 2 is provided on the cooling water passage 7a, the radiator 3 is provided on the cooling water passage 7b, and the electric pump 5 is provided on the cooling water passage 7c. Hereinafter, when the cooling water passages 7a to 7c are not distinguished from each other, they are simply used as the cooling water passage 7.

  The engine (internal combustion engine) 1 is a device that generates power by burning a mixture of supplied fuel and air. For example, the engine 1 is configured by a gasoline engine, a diesel engine, or the like. The engine 1 is mounted on a hybrid vehicle or the like. Further, the engine 1 is provided with a water temperature sensor 6 for detecting the temperature of the cooling water. The water temperature sensor 6 supplies a detection signal S6 corresponding to the detected temperature to the ECU 50.

  The exhaust heat recovery device 2 is provided on an exhaust passage (not shown) through which exhaust gas from the engine 1 passes. The exhaust heat recovery device 2 recovers exhaust heat by allowing cooling water to pass through and exchanging heat between the cooling water and the exhaust gas. Further, the exhaust heat recovery device 2 is configured to be able to switch between execution of heat exchange and restriction of heat exchange. Specifically, such switching is performed according to the operation of a switching valve (not shown) provided in the exhaust passage. The switching valve is controlled by a control signal S2 supplied from the ECU 50.

  In the radiator 3, the cooling water passing through the inside thereof is cooled by outside air. In this case, cooling of the cooling water in the radiator 3 is promoted by the wind introduced by the rotation of the electric fan (not shown). The electric pump (hereinafter also referred to as “electric WP”) 5 includes an electric motor, and the cooling water is circulated in the cooling water passage 7 by driving the motor. Specifically, electric WP5 is supplied with electric power from a battery, and the number of rotations and the like are controlled by a control signal S5 supplied from ECU 50.

  The thermostat 4 is configured by a valve that opens and closes according to the temperature of the cooling water. Basically, the thermostat 4 opens when the temperature of the cooling water becomes high. In this case, the cooling water passage 7 b and the cooling water passage 7 c are connected via the thermostat 4, and the cooling water passes through the radiator 3. Thereby, a cooling water is cooled and the overheating of the engine 1 is suppressed. On the other hand, when the temperature of the cooling water is relatively low, the thermostat 4 is closed. In this case, the cooling water does not pass through the radiator 3. Thereby, since the temperature fall of a cooling water is suppressed, the overcool of the engine 1 is suppressed.

  The ECU (Engine Control Unit) 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). The ECU 50 performs various controls based on the output supplied from the various sensors described above. In the present embodiment, the ECU 50 mainly controls opening and closing of the switching valve in the exhaust heat recovery device 2. Basically, the ECU 50 performs heat exchange in the exhaust heat recovery device 2 so that the exhaust heat is recovered in order to warm up the engine 1 and heat the heater when cold. ) Control the switching valve. On the other hand, the ECU 50 controls the switching valve so that heat exchange is restricted in the exhaust heat recovery device 2 in order to prioritize cooling of the engine 1 during warm.

  Further, the ECU 50 detects an abnormal operation of the switching valve based on the outputs of various sensors. Specifically, the ECU 50 detects the operation abnormality of the switching valve based on the relationship between the operation command supplied to the switching valve and the water temperature, water pressure, etc. acquired when the operation command is issued. Then, when an operation abnormality of the switching valve has occurred, the ECU 50 executes control for coping with this. Thus, the ECU 50 operates as a flow path switching valve control means, an operation abnormality detection means, and an operation abnormality countermeasure execution means.

  The ECU 50 can set the engine 1 to a predetermined operating state when detecting an abnormal operation of the switching valve. The ECU 50 can also set the electric WP 5 in a predetermined driving state when detecting an abnormal operation of the switching valve. By performing such control, it is possible to improve the accuracy of detection of an abnormal operation and to suppress the deterioration of emission and drivability.

[Configuration of exhaust heat recovery unit]
Here, the configuration of the exhaust heat recovery device 2 will be specifically described with reference to FIG. FIG. 2 is a diagram showing a schematic configuration of the exhaust heat recovery device 2 according to the present embodiment. FIG. 2 mainly shows the exhaust system of the engine 1 and the exhaust heat recovery unit 2 described above. A solid line arrow indicates the flow of exhaust gas and cooling water, and a broken line arrow indicates signal input / output.

  The exhaust heat recovery device 2 is provided on an exhaust passage 10 through which exhaust gas from the engine 1 flows. Specifically, the exhaust heat recovery device 2 is installed on the exhaust passage 10 on the downstream side of the catalyst 11 that purifies the exhaust gas.

  The exhaust heat recovery device 2 has a cooling water passage 12 disposed so as to cover the outer wall surface of the exhaust passage 10. For example, the cooling water passage 12 has a shape in which the exhaust passage 10 is spirally wound around the exhaust passage 10. In the cooling water passage 12, the cooling water flows in from the cooling water passage 7a as shown by an arrow B1, and the cooling water flows out to the cooling water passage 7a as shown by an arrow B2.

  Further, a switching valve 15 is provided in the exhaust passage 10. The switching valve 15 switches the exhaust passage through which the exhaust gas passes by opening and closing. Specifically, the switching valve 15 switches between the first exhaust passage 10a and the second exhaust passage 10b. Thereby, execution of heat exchange in the exhaust heat recovery unit 2 and switching of heat exchange in the exhaust heat recovery unit 2 are switched. That is, the switching valve 15 corresponds to the flow path switching valve in the present invention.

  Specifically, when the switching valve 15 is closed, the exhaust gas flows through the first exhaust passage 10a as indicated by arrows A1 and A3. In this case, the exhaust gas passes through a location on the exhaust passage 10 where the cooling water passage 12 in the exhaust heat recovery device 2 is provided. Thereby, exhaust heat is transmitted to the cooling water in the cooling water passage 12 through the wall surface of the exhaust passage 10, and heat exchange is executed. Basically, the switching valve 15 is set to be closed when it is cold. This is because the engine 1 is warmed up or the heater is heated by the exhaust heat recovered by the exhaust heat recovery unit 2.

  On the other hand, when the switching valve 15 is open, the exhaust gas flows through the second exhaust passage 10b as indicated by the arrow A2. In this case, the exhaust gas passes through a passage that bypasses a location on the exhaust passage 10 where the cooling water passage 12 is provided. Therefore, the heat exchange between the exhaust gas and the cooling water is hardly performed (that is, the heat exchange is limited). Basically, the switching valve 15 is set to open when it is warm. This is because the engine 1 is efficiently cooled by the cooling water by restricting the heat exchange in the exhaust heat recovery device 2 to suppress the temperature rise of the cooling water.

  The switching valve 15 is controlled to open and close by a VSV (Vacuum Switching Valve) 16. The VSV 12 is controlled by a control signal S16 (corresponding to the control signal S2 shown in FIG. 1) supplied from the ECU 50. That is, the ECU 50 controls opening / closing of the switching valve 15 via the VSV 12.

  Although the example in which the ECU 50 controls opening and closing of the switching valve 15 has been described above, the ECU 50 can also control the opening degree of the switching valve 15 instead. That is, the flow rate of the exhaust gas passing through the first exhaust passage 10a and the second exhaust passage 10b may be adjusted.

  In the above description, the switching valve 15 switches the passage through which the exhaust gas flows to the first exhaust passage 10a and the second exhaust passage 10b. However, the present invention is not limited to this. In another example, instead of switching the passage through which the exhaust gas flows, it is also possible to switch the execution of heat exchange and the heat exchange limitation by switching the passage through which the cooling water passes. That is, the switching valve and the cooling water passage are configured so that a cooling water passage that passes through a location on the exhaust passage 10 provided with the exhaust heat recovery device 2 and a cooling water passage that bypasses the location can be switched. Also good.

  Below, the detection method of the operation abnormality of the switching valve 15 based on embodiment of this invention, the control performed when the operation abnormality of the switching valve 15 is detected, etc. are demonstrated concretely.

[First Embodiment]
First, a first embodiment of the present invention will be described. In the first embodiment, the ECU 50 detects an abnormal operation of the switching valve 15 based on the coolant temperature. By doing so, malfunction of the engine 1 (deterioration of emission, decrease in engine output, etc.) and destruction of the exhaust heat recovery device 2 are suppressed.

  FIG. 3 is a diagram illustrating a configuration of the exhaust heat recovery device 2 according to the first embodiment. In addition, the same code | symbol is attached | subjected with respect to the same thing as the component shown in FIG. 2, and the description is abbreviate | omitted.

  In the configuration according to the first embodiment, the water temperature sensors 30 and 31 are provided on the cooling water passage 7a. The water temperature sensor 30 detects the temperature of the cooling water flowing upstream of the exhaust heat recovery device 2, and the water temperature sensor 31 detects the temperature of the cooling water flowing downstream of the exhaust heat recovery device 2. That is, the water temperature sensor 30 corresponds to the second water temperature sensor in the present invention, and the water temperature sensor 31 corresponds to the first water temperature sensor in the present invention. The water temperature sensor 30 supplies a detection signal S30 corresponding to the detected temperature to the ECU 50, and the water temperature sensor 31 supplies a detection signal S31 corresponding to the detected temperature to the ECU 50.

  In the first embodiment, the ECU 50 detects an abnormal operation of the switching valve 15 based on the water temperature detected by the water temperature sensors 30 and 31. Specifically, the ECU 50 determines that the switching valve 15 remains open and does not close based on the relationship between the operation command for the switching valve 15 and the temperature difference between the water temperatures detected by the water temperature sensors 30 and 31 (hereinafter referred to as “opening”). And a failure that does not open while the switching valve 15 is closed (hereinafter referred to as a “closed failure”).

  Specifically, the ECU 50 determines that the switching valve 15 is closed when the temperature difference is greater than or equal to a predetermined value when issuing a valve opening command to the switching valve 15. When it is less than the predetermined value, it is determined that the switching valve 15 is normal (not closed). When the switching valve 15 is appropriately opened according to the valve opening command (that is, when it is normal), the heat exchange is limited in the exhaust heat recovery device 2, and the water temperature sensors 30, 31 detect it. It can be said that there is almost no temperature difference in the water temperature, that is, there is almost no difference in the water temperature between the upstream side and the downstream side of the exhaust heat recovery unit 2. Conversely, if there is a temperature difference between the water temperatures detected by the water temperature sensors 30 and 31, it can be said that heat exchange is being performed without the switching valve 15 being closed and opened. Therefore, the ECU 50 determines that the switching valve 15 is closed when the temperature difference is equal to or larger than a predetermined value when the valve opening command is issued to the switching valve 15.

  On the other hand, when the ECU 50 issues a valve closing command to the switching valve 15, if the temperature difference is less than a predetermined value, the ECU 50 determines that the switching valve 15 is open, and conversely, the temperature difference is predetermined. If it is equal to or greater than the value, it is determined that the switching valve 15 is normal (no open failure). When the switching valve 15 is properly closed according to the valve closing command (that is, when it is normal), heat exchange is performed in the exhaust heat recovery device 2, and therefore the water temperature detected by the water temperature sensors 30, 31 is detected. Therefore, it can be said that there is a difference in water temperature between the upstream side and the downstream side of the exhaust heat recovery device 2. Specifically, the temperature detected by the water temperature sensor 31 provided on the downstream side of the exhaust heat recovery device 2 is higher than the temperature detected by the water temperature sensor 30 provided on the upstream side of the exhaust heat recovery device 2. On the contrary, when there is almost no temperature difference between the water temperatures detected by the water temperature sensors 30 and 31, it can be said that the heat exchange is restricted without the switching valve 15 being opened and closed. Therefore, the ECU 50 determines that the switching valve 15 is open when the temperature difference is less than the predetermined value when the valve closing command is issued to the switching valve 15.

  Thus, according to the first embodiment, it is possible to appropriately detect an abnormal operation of the switching valve 15 based on the temperatures detected by the water temperature sensors 30 and 31. As a result, it is possible to suppress the malfunction of the engine 1 and the destruction of the exhaust heat recovery device 2 due to the abnormal operation of the switching valve 15.

  In the above description, an example in which the operation abnormality of the switching valve 15 is detected based on the coolant temperature is shown. However, the operation abnormality of the switching valve 15 may be detected based on the coolant pressure instead of the water temperature. good. Also in this case, the water pressure sensor (corresponding to the second water pressure sensor) that detects the water pressure of the cooling water flowing upstream of the exhaust heat recovery unit 2 and the water pressure of the cooling water flowing downstream of the exhaust heat recovery unit 2 A water pressure sensor (corresponding to the first water pressure sensor) is detected on the cooling water passage 7a, and an abnormal operation of the switching valve 15 can be detected based on the difference in water pressure detected by these. These water pressure sensors can be provided at the same locations as the locations where the water temperature sensors 30 and 31 are provided.

  In the above case, the ECU 50 determines that the switching valve 15 is closed when the difference in water pressure is greater than or equal to a predetermined value when issuing a valve opening command to the switching valve 15. When the switching valve 15 is properly opened according to the valve opening command (that is, when the switching valve 15 is normal), heat exchange is limited in the exhaust heat recovery device 2, so that the difference between the water pressure detected by the water pressure sensor is different. It can be said that there is almost no difference in water pressure between the upstream side and the downstream side of the exhaust heat recovery device 2. Therefore, when there is a difference in the water pressure detected by the water pressure sensor, it can be said that there is nothing but the closing failure of the switching valve 15.

  In contrast, when the ECU 50 issues a valve closing command to the switching valve 15, the ECU 50 determines that the switching valve 15 is open when the difference in water pressure is less than a predetermined value. When the switching valve 15 is properly closed in response to the valve closing command (that is, when the switching valve 15 is normal), heat exchange is performed in the exhaust heat recovery device 2, so that there is a difference between the water pressure detected by the water pressure sensor. That is, it can be said that there is a difference in water pressure between the upstream side and the downstream side of the exhaust heat recovery unit 2. Therefore, when there is almost no difference in the water pressure detected by the water pressure sensor, it can be said that there is nothing but an open failure of the switching valve 15. As described above, the operation abnormality of the switching valve 15 can be appropriately detected based on the water pressure detected by the water pressure sensor.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the second embodiment, instead of the temperature detected by the water temperature sensors 30, 31, the operation of the switching valve 15 is detected based on the temperature detected by the water temperature sensor 6 (see FIG. 1). And different. Specifically, in the second embodiment, the temperature of the cooling water estimated based on the operating state of the engine 1 (hereinafter referred to as “cooling water temperature estimated value”) and the temperature detected by the water temperature sensor 6 (hereinafter referred to as “cooling water temperature estimated value”). (Referred to as “cooling water temperature detection value”)), the operation abnormality of the switching valve 15 is detected.

  Here, with reference to FIG.4 and FIG.5, the detection process of the operation abnormality of the switching valve 15 which concerns on 2nd Embodiment is demonstrated concretely. FIG. 4 is a flowchart showing a process for detecting a closed failure in the switching valve 15. This process is repeatedly executed by the ECU 50 in the cooling system 100 described above at a predetermined cycle.

  First, in step S101, the ECU 50 estimates the coolant temperature when the switching valve 15 is opened. Specifically, the ECU 50 obtains the estimated coolant temperature at the time of opening the valve based on the outside air temperature, the vehicle speed, the estimated exhaust temperature for the engine load, the estimated coolant temperature, the efficiency of the exhaust heat recovery device 2, and the like. . Then, the process proceeds to step S102. In step S102, the ECU 50 issues a valve opening command to the switching valve 15. Then, the process proceeds to step S103.

  In step S103, the ECU 50 compares the detected coolant temperature obtained from the coolant temperature sensor 6 with the estimated coolant temperature obtained in step S101. Specifically, the ECU 50 determines whether or not the detected coolant temperature value exceeds the estimated coolant temperature by a first predetermined temperature or more. In the second embodiment, by making such a determination, a closed failure in the switching valve 15 is detected.

  The reason why the closed failure can be detected by the determination in step S103 is as follows. If the switching valve 15 is normal, the switching valve 15 opens in response to the valve opening command. In this case, since heat exchange is limited in the exhaust heat recovery device 2, it is considered that there is almost no difference between the detected coolant temperature value and the estimated coolant temperature when the valve is opened. Conversely, if the switching valve 15 is closed, the switching valve 15 does not open and remains closed. In this case, since the heat exchange is performed in the exhaust heat recovery device 2, it is considered that the detected coolant temperature is relatively larger than the estimated coolant temperature. As described above, a closed failure in the switching valve 15 can be detected by comparing the detected coolant temperature value with the estimated coolant temperature value.

  When the detected coolant temperature value exceeds the estimated coolant temperature by a first predetermined temperature or more (step S103; Yes), the process proceeds to step S104. In this case, the ECU 50 determines in step S104 that the switching valve 15 has a closed failure. As described above, when the detected coolant temperature exceeds the estimated coolant temperature by the first predetermined temperature or more, heat exchange is performed in the exhaust heat recovery device 2 without opening due to the switching valve 15 being closed. Can be said to have been executed. When the above process ends, the process exits the flow.

  On the other hand, when the detected coolant temperature does not exceed the estimated coolant temperature by the first predetermined temperature or more (step S103; No), the process proceeds to step S105. In this case, the ECU 50 determines in step S105 that the switching valve 15 is normal. That is, the ECU 50 determines that the switching valve 15 is not closed. As described above, when the detected coolant temperature does not exceed the estimated coolant temperature by the first predetermined temperature or more, the switching valve 15 is appropriately opened, and the heat exchange in the exhaust heat recovery device 2 is restricted. It can be said that there is nothing else. When the above process ends, the process exits the flow. According to the above processing, it is possible to appropriately detect a closed failure of the switching valve 15.

  Next, detection of an open failure in the switching valve 15 will be described. FIG. 5 is a flowchart showing an open failure detection process of the switching valve 15. This process is also repeatedly executed by the ECU 50 in the cooling system 100 described above at a predetermined cycle.

  First, in step S201, the ECU 50 estimates the cooling water temperature when the switching valve 15 is closed. Specifically, the ECU 50 obtains the estimated coolant temperature when the valve is closed based on the outside air temperature, the vehicle speed, the estimated exhaust temperature for the engine load, the estimated coolant temperature, the efficiency of the exhaust heat recovery unit 2, and the like. . Then, the process proceeds to step S202. In step S202, the ECU 50 issues a valve closing command to the switching valve 15. Then, the process proceeds to step S203.

  In step S203, the ECU 50 compares the detected coolant temperature obtained from the coolant temperature sensor 6 with the estimated coolant temperature obtained in step S201. Specifically, the ECU 50 determines whether or not the estimated coolant temperature exceeds the coolant temperature detection value by a second predetermined temperature or more. In the second embodiment, an open failure in the switching valve 15 is detected by making such a determination.

  The reason why the open failure can be detected based on the determination in step S203 is as follows. If the switching valve 15 is normal, the switching valve 15 is closed in response to the valve closing command. In this case, since the heat exchange is performed in the exhaust heat recovery unit 2, it is considered that there is almost no difference between the estimated coolant temperature and the detected coolant temperature when the valve is closed. On the other hand, if the switching valve 15 has an open failure, the switching valve 15 does not close and remains open. In this case, since the heat exchange is limited in the exhaust heat recovery device 2, it is considered that the detected coolant temperature is relatively smaller than the estimated coolant temperature. As described above, an open failure in the switching valve 15 can be detected by comparing the detected coolant temperature value with the estimated coolant temperature value.

  When the estimated coolant temperature exceeds the detected coolant temperature by a second predetermined temperature or more (step S203; Yes), the process proceeds to step S204. In this case, the ECU 50 determines in step S204 that the switching valve 15 has an open failure. As described above, when the estimated coolant temperature exceeds the coolant temperature detection value by the second predetermined temperature or more, heat is exchanged in the exhaust heat recovery device 2 without closing because the switching valve 15 is open. It can be said that there is nothing but a restriction. When the above process ends, the process exits the flow.

  On the other hand, when the estimated coolant temperature does not exceed the detected coolant temperature by the second predetermined temperature or more (step S203; No), the process proceeds to step S205. In this case, the ECU 50 determines that the switching valve 15 is normal in step S205. That is, the ECU 50 determines that the switching valve 15 has not opened. As described above, when the estimated coolant temperature does not exceed the detected coolant temperature by the second predetermined temperature or more, the switching valve 15 is appropriately closed and heat exchange is performed in the exhaust heat recovery device 2. It can be said that there is nothing else. When the above process ends, the process exits the flow.

  As described above, according to the second embodiment, it is possible to appropriately detect the closing failure and the opening failure of the switching valve 15. Further, in the second embodiment, since the operation abnormality of the switching valve 15 can be appropriately detected based on the water temperature sensor 6 provided in the normal engine, for example, a potentiometer or the like is provided in the switching valve 15. Based on this, since it is not necessary to detect an abnormal operation of the switching valve 15, the cost of the apparatus can be reduced.

  In addition, although the example which performs the close failure and the open failure of the switching valve 15 separately was shown above, it is not limited to this. In another example, the closing failure and the opening failure of the switching valve 15 can be performed in one process.

  Moreover, although the example which detects the operation abnormality of the switching valve 15 by comparing a cooling water temperature estimated value and a cooling water temperature detection value was shown above, it is not limited to this. In another example, the operation abnormality of the switching valve 15 can be detected based on a change in the detected coolant temperature instead of using the estimated coolant temperature. For example, when a valve opening command is issued to the switching valve 15, if the detected coolant temperature does not decrease, it can be determined that a closing failure has occurred. In addition, when the valve closing command is issued to the switching valve 15, if the detected coolant temperature does not increase, it can be determined that an open failure has occurred.

  Furthermore, although the example which detected the operation abnormality of the switching valve 15 based on the cooling water temperature was shown above, it is also possible to detect the operation abnormality of the switching valve 15 based on the coolant pressure instead of the cooling water temperature. It is. Specifically, the switching valve is compared by comparing the cooling water pressure estimated based on the operating state of the engine 1 and the detected cooling water pressure or based on a change in the cooling water pressure. 15 operational abnormalities can be detected.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment and the second embodiment described above in that control for coping with the abnormal operation of the switching valve 15 is executed. Specifically, in the control according to the third embodiment, when the switching valve 15 is closed, the cooling water temperature rises due to excessive recovery of the exhaust heat by the exhaust heat recovery device 2, and the engine 1 is overheated. This is done to prevent this. Specifically, in the third embodiment, in order to suppress an increase in the cooling water temperature, control is performed to increase the flow rate of the electric WP5 or to circulate the cooling water through the heater core to promote heat dissipation.

  FIG. 6 is a flowchart showing the control executed when the closing failure of the switching valve 15 occurs. This process is repeatedly executed by the ECU 50 in the cooling system 100 described above at a predetermined cycle.

  First, in step S301, the ECU 50 determines whether or not the switching valve 15 is closed. The determination as to whether or not the switching valve 15 is closed can be made by executing the processing described in the first and second embodiments. When the switching valve 15 has a closed failure (step S301; Yes), the process proceeds to step S303. On the other hand, when the switching valve 15 is not closed (step S301; No), the process proceeds to step S302. In this case, the ECU 50 executes normal control (step S302). That is, the control for suppressing the rise of the cooling water temperature is not executed. Then, the process exits the flow.

  In step S303, the ECU 50 turns on a failure lamp indicating that the switching valve 15 is closed. Then, the process proceeds to step S304.

  In step S304, the ECU 50 determines whether or not the detected coolant temperature value acquired from the coolant temperature sensor 6 has exceeded the first upper limit value. Here, it is determined whether or not the temperature of the cooling water should be suppressed. When the detected coolant temperature value exceeds the first upper limit value (step S304; Yes), the process proceeds to step S305. In this case, it can be said that it is the situation which should suppress the raise of a cooling water temperature. In other words, it can be said that there is a possibility of overheating. On the other hand, when the coolant temperature detection value does not exceed the first upper limit value (step S304; No), the process exits the flow. In this case, it can be said that there is no need to suppress an increase in the cooling water temperature.

  In step S305, the ECU 50 fully opens the electric WP5 (maximum rotation), that is, increases the flow rate of the electric WP5. As described above, by fully opening the electric WP5, it is possible to appropriately suppress an increase in the coolant temperature. Then, the process proceeds to step S306.

  In step S306, the ECU 50 determines whether or not the detected coolant temperature value acquired from the coolant temperature sensor 6 exceeds the second upper limit value. The second upper limit value is a value larger than the first upper limit value used in step S304. Here, it is determined whether or not the control for suppressing the rise in the coolant temperature should be further performed. When the detected coolant temperature value exceeds the second upper limit value (step S306; Yes), the process proceeds to step S307. In this case, it can be said that the control for further suppressing the rise in the cooling water temperature should be further performed. On the other hand, when the coolant temperature detection value does not exceed the second upper limit value (step S306; No), the process exits the flow. In this case, it can be said that it is not necessary to further perform control for suppressing an increase in the cooling water temperature.

  In step S307, the ECU 50 performs control to fully open the heater blower (maximum rotation) in order to maximize the amount of heat released from the heater core. The heater core is provided on the cooling water passage 7, and the heater blower is provided in the vicinity of the heater core. By controlling the electric WP 5 to fully open and the heater blower to fully open in this way, it is possible to effectively suppress an increase in the cooling water temperature and to reliably suppress overheating of the engine 1. It becomes. When the above process ends, the process exits the flow.

  Thus, according to 3rd Embodiment, when the abnormal operation of the switching valve 15 generate | occur | produces, the raise of a cooling water temperature can be suppressed appropriately. Therefore, overheating of the engine 1 can be effectively suppressed.

  In addition, although the example which performs only the control which fully opens a heater blower when the cooling water temperature detection value has exceeded the 2nd upper limit value was shown above, it is not limited to this. In another example, when the detected coolant temperature exceeds the second upper limit value, the heater blower is fully opened, and the electric fan provided near the radiator 3 is fully opened (maximum rotation), and EGR is performed. Control can be performed to set the valve to closed. Thereby, it becomes possible to suppress the increase in the cooling water temperature more effectively.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, instead of detecting an abnormal operation of the switching valve 15 as in the first and second embodiments described above, an abnormality of the thermostat 4 and the water temperature sensor 6 (see FIG. 1) is detected. This is different from the first embodiment described above. That is, in the fourth embodiment, when an abnormality occurs in the cooling system 100 (for example, when the increase is not detected in a situation where the cooling water temperature increases), the cause of the abnormality is the thermostat 4. Whether the water temperature sensor 6 is abnormal or not.

  FIG. 7 is a flowchart showing an abnormality detection process of the thermostat 4 and the water temperature sensor 6 according to the fourth embodiment. This process is repeatedly executed by the ECU 50 in the cooling system 100 described above at a predetermined cycle.

  First, in step S401, the ECU 50 determines whether or not the situation is after the coolant temperature has risen to some extent. In the fourth embodiment, such a determination is made because the abnormality of the thermostat 4 and the water temperature sensor 6 is detected based on the change in the cooling water temperature. This is because detection cannot be performed. Specifically, in step S401, the ECU 50 determines whether or not the cumulative intake air amount is greater than a first predetermined value. The cumulative intake air amount corresponds to the amount of heat generated by the engine 1, in other words, the amount of heat of cooling (cooling loss). Therefore, based on the cumulative intake air amount, it can be determined whether or not the situation is after the cooling water temperature has risen to some extent. In this case, the first predetermined value is set to a cumulative intake air amount such that the cooling water temperature rises to some extent.

  When the accumulated intake air amount is larger than the first predetermined value (step S401; Yes), the process proceeds to step S402. On the other hand, when the accumulated intake air amount is equal to or less than the first predetermined value (step S401; No), the process exits the flow. In this case, since it cannot be said that the abnormality detection can be performed with high accuracy, the processing is terminated without detecting the abnormality.

  In step S402, the ECU 50 determines whether or not the change amount of the water temperature detected by the water temperature sensor 6 (hereinafter referred to as “THW change amount”) is less than a second predetermined value. Here, based on the THW change amount, it is determined whether at least one of the thermostat 4 and the water temperature sensor 6 is abnormal. In the situation where the process of step S402 is being executed, the exhaust heat is exhausted when the thermostat 4 is normal (ie, when the thermostat 4 is closed) because the accumulated intake air amount is larger than the first predetermined value. The actual cooling water temperature should have risen due to the recovery of water. Therefore, it can be said that the abnormality of the thermostat 4 and the water temperature sensor 6 can be detected by using the THW change amount detected by the water temperature sensor 6.

  If the THW change amount is less than the second predetermined value (step S402; Yes), the process proceeds to step S403. In this case, since the detected cooling water temperature has hardly changed, it is considered that at least one of the thermostat 4 and the water temperature sensor 6 is abnormal. Therefore, ECU50 determines with the thermostat 4 or the water temperature sensor 6 being abnormal in step S403. In this case, it is considered that the thermostat 4 has an open failure or the water temperature sensor 6 has failed. When this process ends, the process proceeds to step S404. On the other hand, when the THW change amount is equal to or greater than the second predetermined value (step S402; No), the process exits the flow. In this case, it can be said that the thermostat 4 and the water temperature sensor 6 are normal.

  In step S404, the ECU 50 stops the electric WP5. Thus, when electric WP5 is stopped, in the situation where processing of Step S404 is performed, it is thought that actual cooling water temperature changes. Therefore, in order to determine which of the thermostat 4 and the water temperature sensor 6 is abnormal based on the cooling water temperature, the electric WP 5 is stopped in step S404. When the above process ends, the process proceeds to step S405.

  In step S405, the ECU 50 determines whether or not the cumulative intake air amount is greater than a third predetermined value. This determination is performed to wait until a certain change occurs in the actual cooling water temperature. This is because if the actual cooling water temperature does not change, the abnormality determination cannot be performed with high accuracy. If the accumulated intake air amount is larger than the third predetermined value (step S405; Yes), the process proceeds to step S406. On the other hand, when the cumulative intake air amount is less than the third predetermined value (step S405; No), the process exits the flow. In this case, since it is highly possible that the determination cannot be performed with high accuracy, the process is terminated without performing the abnormality determination.

  In step S406, the ECU 50 determines whether or not the THW change amount is larger than a fourth predetermined value. Here, based on the THW change amount, it is determined which of the thermostat 4 and the water temperature sensor 6 is abnormal. In the situation where the process of step S406 is being executed, the actual cooling water temperature should have changed. Specifically, it is considered that the actual cooling water temperature is rising. Therefore, it can be said that the abnormality of the thermostat 4 and the water temperature sensor 6 can be detected by using the THW change amount detected by the water temperature sensor 6.

  When the THW change amount is larger than the fourth predetermined value (step S406; Yes), the process proceeds to step S407. In this case, the coolant temperature sensor 6 detects the actual change in the coolant temperature. Specifically, an increase in cooling water temperature is detected. Therefore, it can be said that the water temperature sensor 6 is normal. Therefore, the ECU 50 determines that the thermostat 4 is abnormal in step S407. This determination is nothing but the fact that the cooling water temperature hardly changes until the electric WP 5 is stopped, and the thermostat 4 remains open and not closed when the cooling water temperature rises after the electric WP 5 is stopped. Because. Therefore, the ECU 50 determines that the thermostat 4 has an open failure. When the above process ends, the process exits the flow.

  On the other hand, when the THW change amount is equal to or smaller than the fourth predetermined value (step S406; No), the process proceeds to step S408. In this case, although the actual cooling water temperature has changed, the water temperature sensor 6 has not detected any change in the cooling water temperature. Accordingly, the ECU 50 determines in step S408 that the water temperature sensor 6 is abnormal. Then, the process exits the flow.

  Thus, according to the fourth embodiment, abnormality detection of the thermostat 4 and the water temperature sensor 6 can be performed with high accuracy.

  In addition, although the example which stops the electric WP5 when performing abnormality detection of the thermostat 4 and the water temperature sensor 6 has been described above, the invention is not limited thereto. In another example, when the engine 1 is at a high speed, a high load, or the like, the abnormality detection described above can be performed by performing control to increase the flow rate of the electric WP5 instead of stopping the electric WP5. . This is because the heat of the engine 1 can be efficiently taken away by increasing the flow rate of the electric WP5.

  Furthermore, when the abnormality of the water temperature sensor 6 is detected by the above processing, the ECU 50 can prohibit the detection of the operation abnormality of the switching valve 15 as described above. This is because when the water temperature sensor 6 is abnormal, an abnormal operation of the switching valve 15 cannot be detected with high accuracy. Thus, by prohibiting the detection of the operation abnormality of the switching valve 15, the detection accuracy for the operation abnormality of the switching valve 15 can be ensured.

  Further, when an open failure of the thermostat 4 is detected, the ECU 50 can cancel the control of the switching valve 15 performed to limit heat exchange in the exhaust heat recovery device 2. That is, the switching valve 15 is controlled to be closed so that the exhaust heat recovery is performed in the exhaust heat recovery unit 2. When the thermostat 4 has an open failure, the cooling water is cooled by the radiator 3 and the temperature of the engine 1 tends to decrease. By recovering the exhaust heat as described above, the cooling water temperature is reduced. Can be suppressed. Therefore, overcooling of the engine 1 due to the open failure of the thermostat 4 can be appropriately suppressed.

1 is a diagram illustrating a schematic configuration of a cooling system to which an exhaust heat recovery apparatus according to an embodiment is applied. It is a figure showing a schematic structure of an exhaust heat recovery device concerning this embodiment. It is a figure which shows the structure etc. of the exhaust heat recovery device which concern on 1st Embodiment. It is a flowchart which shows the detection process of the closed failure in a switching valve. It is a flowchart which shows the detection process of the open failure in a switching valve. It is a flowchart which shows the control performed when the close failure of a switching valve arises. It is a flowchart which shows the abnormality detection process of a thermostat and a water temperature sensor.

Explanation of symbols

1 engine (internal combustion engine)
2 Exhaust heat recovery device 3 Radiator 4 Thermostat 5 Electric pump (Electric WP)
6, 30, 31 Water temperature sensor 7 Cooling water passage 10 Exhaust passage 10a First exhaust passage 10b Second exhaust passage 15 Switching valve 50 ECU
100 Cooling system

Claims (20)

Exhaust heat of the internal combustion engine, which is disposed on the exhaust passage of the internal combustion engine and has an exhaust heat recovery device that exchanges heat between the cooling water passing through the interior and the exhaust gas, and an electric pump that circulates the cooling water A recovery device,
A flow path switching valve for controlling a flow rate of at least one of the exhaust gas and the cooling water passing through a location on an exhaust passage provided with the exhaust heat recovery device;
Channel switching valve control means for controlling the channel switching valve;
An operation abnormality detecting means for detecting an operation abnormality of the flow path switching valve;
An internal combustion engine comprising: an operational abnormality countermeasure executing means for executing control for coping with the operational abnormality when the operational abnormality detection means detects an operational abnormality of the flow path switching valve. Exhaust heat recovery device.   The flow path switching valve is configured to control a flow rate of exhaust gas flowing through a first exhaust passage that passes through a location on the exhaust passage provided with the exhaust heat recovery device and a second exhaust passage that bypasses the location. 2. The exhaust heat recovery apparatus for an internal combustion engine according to claim 1, wherein the exhaust heat recovery apparatus is configured to be adjusted.   The operation abnormality detecting means detects an operation abnormality of the flow path switching valve based on a relationship between an operation command for the flow path switching valve and a temperature of the cooling water detected by a water temperature sensor. The exhaust heat recovery device for an internal combustion engine according to claim 2. A first water temperature sensor for detecting a temperature of cooling water flowing downstream of the exhaust heat recovery unit;
The exhaust heat recovery device for an internal combustion engine according to claim 3, wherein the operation abnormality detection means detects an operation abnormality of the flow path switching valve based on the temperature detected by the first water temperature sensor. .   The operation abnormality detection means is configured to control the flow rate of the exhaust gas flowing into the first exhaust passage so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. When the path switching valve is controlled, the temperature of the cooling water is estimated based on at least the operating state of the internal combustion engine, and the temperature detected by the first water temperature sensor exceeds the estimated temperature by a predetermined value or more Or when the temperature detected by the first water temperature sensor does not decrease, it is determined that an abnormality has occurred in the operation of the flow path switching valve for limiting heat exchange by the exhaust heat recovery device. The exhaust heat recovery device for an internal combustion engine according to claim 4. A second water temperature sensor for detecting the temperature of the cooling water flowing upstream of the exhaust heat recovery unit;
The operation abnormality detecting means detects an operation abnormality of the flow path switching valve based on a temperature detected by the first water temperature sensor and a temperature detected by the second water temperature sensor. Item 5. An exhaust heat recovery apparatus for an internal combustion engine according to Item 4.   The operation abnormality detection means is configured to control the flow rate of the exhaust gas flowing into the first exhaust passage so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. When the difference between the temperature detected by the first water temperature sensor and the temperature detected by the second water temperature sensor is greater than or equal to a predetermined value when the path switching valve is controlled, heat exchange by the exhaust heat recovery device is performed. The exhaust heat recovery apparatus for an internal combustion engine according to claim 6, wherein it is determined that an abnormality has occurred in the operation of the flow path switching valve for limiting.   3. The operation abnormality detecting unit detects an operation abnormality of the flow path switching valve based on a relationship between an operation command for the flow path switching valve and a water pressure of the cooling water. Exhaust heat recovery device for internal combustion engine. A first water pressure sensor that detects a water pressure of the cooling water flowing downstream of the exhaust heat recovery unit;
The exhaust heat recovery device for an internal combustion engine according to claim 8, wherein the operation abnormality detection means detects an operation abnormality of the flow path switching valve based on a water pressure detected by the first water pressure sensor. .   The operation abnormality detection means is configured to control the flow rate of the exhaust gas flowing into the first exhaust passage so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. When the path switching valve is controlled, the cooling water pressure is estimated based on at least the operating state of the internal combustion engine, and the water pressure detected by the first water pressure sensor exceeds the estimated water pressure by a predetermined value or more. If the water pressure detected by the first water pressure sensor does not decrease, it is determined that an abnormality has occurred in the operation of the flow path switching valve for limiting heat exchange by the exhaust heat recovery device. An exhaust heat recovery device for an internal combustion engine according to claim 9. A second water pressure sensor for detecting the water pressure of the cooling water flowing upstream of the exhaust heat recovery unit;
The operation abnormality detecting means detects an operation abnormality of the flow path switching valve based on a water pressure detected by the first water pressure sensor and a water pressure detected by the second water pressure sensor. Item 10. An exhaust heat recovery apparatus for an internal combustion engine according to Item 9.   The operation abnormality detection means is configured to control the flow rate of the exhaust gas flowing into the first exhaust passage so that the flow path switching valve control means restricts heat exchange by the exhaust heat recovery device. When the difference between the water pressure detected by the first water pressure sensor and the water pressure detected by the second water pressure sensor is greater than or equal to a predetermined value when the path switching valve is controlled, heat exchange by the exhaust heat recovery device is performed. The exhaust heat recovery apparatus for an internal combustion engine according to claim 11, wherein it is determined that an abnormality has occurred in the operation of the flow path switching valve for limiting.   The operation abnormality countermeasure executing means is a control for increasing the flow rate of the electric pump when the operation abnormality detecting means determines that an abnormality has occurred in the operation of the flow path switching valve for restricting heat exchange. The exhaust heat recovery device for an internal combustion engine according to any one of claims 2 to 12, wherein:   The operation abnormality countermeasure executing means further performs control to circulate the cooling water through the heater core and promote heat dissipation when a predetermined condition is satisfied after performing control to increase the flow rate of the electric pump. The exhaust heat recovery device for an internal combustion engine according to claim 13. The internal combustion engine is mounted on a hybrid vehicle,
15. The apparatus according to claim 1, further comprising means for setting the internal combustion engine to a predetermined operation state when the operation abnormality detection unit detects the operation abnormality of the flow path switching valve. An exhaust heat recovery device for an internal combustion engine according to item.   15. The apparatus according to claim 1, further comprising: a unit configured to set the electric pump to a predetermined driving state when detecting the operation abnormality of the flow path switching valve by the operation abnormality detection unit. An exhaust heat recovery device for an internal combustion engine according to the item.   The exhaust heat recovery apparatus for an internal combustion engine according to claim 2, further comprising means for detecting an abnormality of the water temperature sensor in a state where the electric pump is stopped.   18. The exhaust heat recovery of the internal combustion engine according to claim 17, further comprising means for prohibiting detection of an operation abnormality of the flow path switching valve by the operation abnormality detection means when an abnormality of the water temperature sensor is detected. apparatus.   In the case where no abnormality is detected in the water temperature sensor, there is provided means for determining that the thermostat is abnormal when a change in the temperature of the cooling water is detected by the water temperature sensor after the internal combustion engine is started. An exhaust heat recovery device for an internal combustion engine according to claim 17.   The flow path switching valve control means cancels the operation of the flow path switching valve for limiting heat exchange by the exhaust heat recovery device when an abnormality of the thermostat is detected. 2. An exhaust heat recovery device for an internal combustion engine according to 1.

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