JP2010065671A - Failure diagnosis device of cooling system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve failure diagnosis accuracy of an electric W/P (electric water pump) provided in an engine cooling system. <P>SOLUTION: This device is provided with: an inlet side water temperature sensor 20 detecting inlet water temperature of an engine 11 (cooling water temperature near a cooling water inlet); and an outlet side water temperature sensor 21 detecting outlet water temperature of the engine 11 (cooling water temperature near a cooling water outlet). Since received heat quantity of cooling water increases in the engine 11 if flow rate of the cooling water drops due to a failure of the electric W/P 12, a difference between inlet water temperature and outlet water temperature of the engine 11 becomes abnormally large. By paying attention to the phenomenon, inlet and outlet water temperature difference which is a difference between outlet water temperature detection value detected by the outlet side water temperature sensor 21 and inlet water temperature detection value detected by the inlet side water temperature sensor 20 is found, and occurrence of a failure in the electric W/P 12 is determined if the inlet and outlet water temperature difference become failure determination value corresponding to a vehicle operation state, or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a failure diagnosis device for a cooling system for a vehicle including an electric water pump that circulates cooling water between an internal combustion engine and a radiator.

In some cooling systems for internal combustion engines mounted on vehicles, cooling water is circulated between the internal combustion engine and the radiator by an electric water pump. As described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-336626), as a failure diagnosis of a cooling system provided with such an electric water pump, a cooling water temperature sensor is provided near the cooling water outlet of the internal combustion engine. Only one is provided, and the presence or absence of a failure of the electric water pump is determined depending on whether or not the amount of change in the coolant temperature detected by the coolant temperature sensor exceeds a predetermined value.
Japanese Patent Laying-Open No. 2006-336626 (page 8, FIG. 4 etc.)

  However, in the failure diagnosis of the above-mentioned Patent Document 1, it is determined that a failure has occurred in the electric water pump when the amount of change in the cooling water temperature detected by one cooling water temperature sensor exceeds a predetermined value. Despite the normal operation of the water pump, the cooling water temperature rises abnormally due to a failure of the electric cooling fan that generates cooling air for the radiator, and the amount of change in the cooling water temperature detected by the cooling water temperature sensor is When the predetermined value is exceeded, there is a possibility that the electric water pump that is operating normally is erroneously determined as a failure.

  The present invention has been made in consideration of such circumstances, and therefore the object of the present invention is to provide fault diagnosis accuracy for components of a vehicle cooling system (for example, an electric water pump, an electric cooling fan, etc.). It is an object of the present invention to provide a failure diagnosis apparatus for a vehicle cooling system that can improve the efficiency.

  In order to achieve the above object, an invention according to claim 1 is directed to a failure diagnosis apparatus for a cooling system for a vehicle including an electric water pump that circulates cooling water between the internal combustion engine and a radiator. An inlet-side water temperature sensor that detects a cooling water temperature at or near the water inlet (hereinafter referred to as “inlet water temperature”), and an outlet side that detects the cooling water outlet of the internal combustion engine or a cooling water temperature near it (hereinafter referred to as “outlet water temperature”). Comparing the difference or ratio between the outlet water temperature detection value detected by the outlet side water temperature sensor and the inlet water temperature detection value detected by the inlet side water temperature sensor by the failure diagnosis means with the failure judgment value according to the vehicle operating condition Thus, it is determined whether or not there is a failure in the electric water pump.

  When the flow rate of the cooling water decreases due to a failure of the electric water pump, the time for the cooling water to pass through the internal combustion engine (the time for the cooling water to receive heat from the internal combustion engine) becomes longer, and the amount of heat received by the cooling water in the internal combustion engine becomes smaller. Therefore, the outlet water temperature becomes abnormally high with respect to the inlet water temperature of the internal combustion engine, and the difference between the outlet water temperature and the inlet water temperature becomes abnormally large. On the other hand, even if the amount of heat dissipated in the cooling water in the radiator changes due to a failure of the electric cooling fan, etc., if the electric water pump operates normally and the cooling water circulates normally, the cooling in the internal combustion engine Since the amount of heat received by water does not change much, the difference between the outlet water temperature and the inlet water temperature of the internal combustion engine does not change much.

  Therefore, if the difference or ratio between the outlet water temperature detection value detected by the outlet side water temperature sensor and the inlet water temperature detection value detected by the inlet side water temperature sensor is compared with the failure judgment value, the presence or absence of failure of the electric water pump can be accurately determined. Can be determined. In addition, since the failure determination value according to the vehicle operating state is used, the amount of heat generated by the internal combustion engine (the amount of heat received by the cooling water in the internal combustion engine) changes according to the vehicle operating state, and the outlet water temperature and the inlet water temperature Corresponding to the change in the difference, the failure determination value can be changed to set the failure determination value to an appropriate value, and the failure diagnosis accuracy of the electric water pump can be further improved.

  In this case, as in claim 2, when the difference between the detected outlet water temperature value and the detected inlet water temperature value is greater than or equal to the failure determination value, it may be determined that a failure has occurred in the electric water pump. When the flow rate of the cooling water decreases due to a failure of the electric water pump, the time for the cooling water to pass through the internal combustion engine (the time for the cooling water to receive heat from the internal combustion engine) becomes longer, and the outlet water temperature and the inlet water temperature of the internal combustion engine Since the difference becomes abnormally large, when the difference between the outlet water temperature detection value and the inlet water temperature detection value is equal to or greater than the failure determination value, it can be determined that a failure has occurred in the electric water pump.

  Further, as in claim 3, when the outlet water temperature detection value is equal to or higher than a predetermined value, it may be determined that the electric water pump has failed. When the flow rate of cooling water decreases due to a failure of the electric water pump, the outlet water temperature of the internal combustion engine becomes abnormally high. Therefore, even when the detected outlet water temperature is abnormally high, it is determined that the electric water pump has failed. Can do.

  Further, as in claim 4, the actual amount of heat received by the cooling water in the internal combustion engine is actually calculated based on the difference between the detected outlet water temperature detected by the outlet water temperature sensor and the detected inlet water temperature detected by the inlet water temperature sensor. The amount of heat received is calculated by the heat receiving amount calculating means, and the amount of heat received by the internal combustion engine is estimated by the heat receiving amount estimating means based on the heat generation amount obtained from the operating state of the internal combustion engine and the target flow rate of the cooling water. It may be possible to determine whether or not there is a failure in the electric water pump by comparing the actual amount of received heat of the cooling water calculated by the calculating means and the estimated amount of received heat of the cooling water estimated by the heat receiving amount estimating means.

  If the flow rate of cooling water decreases due to a failure of the electric water pump, the difference between the outlet water temperature and the inlet water temperature of the internal combustion engine becomes abnormally large.Therefore, the outlet water temperature detection value detected by the outlet water temperature sensor and the inlet water temperature sensor The actual heat receiving amount of the cooling water obtained from the difference from the detected inlet water temperature detection value becomes abnormally large. Therefore, if the actual amount of heat received by the cooling water is compared with the estimated amount of heat received by the cooling water, it is possible to accurately determine whether or not the electric water pump has failed.

  Further, as in claim 5, the amount of heat received by the internal combustion engine is estimated by the heat receiving amount estimating means based on the amount of heat generated from the operating state of the internal combustion engine and the target flow rate of the cooling water, and the inlet side The outlet water temperature estimated value detected by the outlet water temperature sensor is estimated by the outlet water temperature estimating means based on the detected inlet water temperature value detected by the water temperature sensor and the estimated received heat quantity of the cooling water estimated by the received heat quantity estimating means. And the outlet water temperature estimated value estimated by the outlet water temperature estimating means may be compared to determine the presence or absence of a failure of the electric water pump.

  When the flow rate of the cooling water decreases due to a failure of the electric water pump, the outlet water temperature of the internal combustion engine becomes abnormally high, and the detected outlet water temperature detected by the outlet side water temperature sensor becomes abnormally high. Therefore, if the outlet water temperature detection value and the outlet water temperature estimation value are compared, the presence or absence of a failure of the electric water pump can be accurately determined.

  Alternatively, the amount of heat received by the internal combustion engine is estimated by the heat receiving amount estimating means based on the heat generation amount obtained from the operating state of the internal combustion engine and the target flow rate of the cooling water, and the outlet The inlet water temperature is estimated by the inlet water temperature estimation means based on the detected outlet water temperature value detected by the side water temperature sensor and the estimated received heat quantity of the cooling water estimated by the received heat quantity estimation means, and detected by the inlet water temperature sensor. The value may be compared with the estimated inlet water temperature estimated by the inlet water temperature estimating means to determine whether or not the electric water pump has failed.

  If the flow rate of cooling water decreases due to a failure of the electric water pump, the outlet water temperature of the internal combustion engine becomes abnormally high and the detected outlet water temperature detected by the outlet water temperature sensor becomes abnormally high. The estimated inlet water temperature obtained from the estimated amount of heat received from the cooling water becomes abnormally high. Therefore, if the detected inlet water temperature is compared with the estimated inlet water temperature, it is possible to accurately determine whether or not the electric water pump has failed.

  Further, as in claim 7, an electric water pump for circulating cooling water between the internal combustion engine and the radiator, an electric cooling fan for generating cooling air for the radiator, and a flow path for circulating the cooling water to the radiator And a cooling system for a vehicle cooling system having a flow path switching valve that switches between a bypass flow path that does not circulate cooling water in the radiator, a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature") And an outlet-side water temperature sensor for detecting the cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”), and the amount of heat dissipated in the radiator. The amount of heat radiation of the cooling water in the radiator is estimated by the heat radiation amount estimation means based on the factor that determines the outlet water temperature detection value detected by the outlet water temperature sensor and the heat radiation. The inlet water temperature is estimated by the inlet water temperature estimating means based on the estimated heat dissipation amount of the cooling water estimated by the estimating means, and the inlet water temperature detected value detected by the inlet water temperature sensor and the inlet water temperature estimated value estimated by the inlet water temperature estimating means. And the presence or absence of failure of the electric cooling fan or the flow path switching valve may be determined.

  If the flow rate of the cooling air decreases due to a failure of the electric cooling fan, or if the flow rate of the cooling water circulating to the radiator decreases due to a failure of the flow path switching valve, the heat dissipation amount of the cooling water at the radiator decreases. The inlet temperature of the internal combustion engine becomes abnormally high, and the detected inlet water temperature detected by the inlet side water temperature sensor becomes abnormally high. Therefore, if the detected inlet water temperature is compared with the estimated inlet water temperature, it is possible to accurately determine whether or not the electric cooling fan or the flow path switching valve has failed.

  Alternatively, as in claim 8, the actual heat dissipation amount of the cooling water at the radiator is calculated based on the difference between the detected outlet water temperature detected by the outlet water temperature sensor and the detected inlet water temperature by the inlet water temperature sensor. Calculated by the heat dissipation amount calculation means, and based on the factors that determine the heat dissipation amount of the cooling water in the radiator, the heat dissipation amount of the cooling water in the radiator is estimated by the heat dissipation amount estimation means, and calculated by the actual heat dissipation amount calculation means. It is also possible to determine whether or not there is a failure in the electric cooling fan or the flow path switching valve by comparing the actual heat dissipation amount of the cooling water with the estimated heat dissipation amount estimated by the heat dissipation amount estimation means.

  If the flow rate of the cooling air decreases due to a failure of the electric cooling fan, or if the flow rate of the cooling water circulating to the radiator decreases due to a failure of the flow path switching valve, the heat dissipation amount of the cooling water at the radiator decreases. The actual heat release amount of the cooling water in the radiator, which is obtained from the difference between the detected outlet water temperature detected by the outlet water temperature sensor and the detected inlet water temperature detected by the inlet water temperature sensor, becomes abnormally small. Therefore, if the actual heat dissipation amount of the cooling water is compared with the estimated value of the heat dissipation amount of the cooling water, it is possible to accurately determine whether or not the electric cooling fan or the flow path switching valve has failed.

  By the way, in a cooling system equipped with an electric water pump, a request to stop the electric water pump may occur for early warming up of the internal combustion engine. However, when an electric water pump stop request is generated, there is a distinction between a state in which the electric water pump is stopped normally in response to the stop request and a state in which the electric water pump is stopped due to a failure of the electric water pump. It cannot be judged separately.

  Also, when the electric water pump stops and the circulation of the cooling water stops, the amount of heat dissipated in the cooling water in the radiator decreases, and the cooling water in the radiator is lost due to a failure of the electric cooling fan or the flow path switching valve. Since the state is similar to the state in which the amount of heat radiation is reduced, it is difficult to accurately determine whether or not the electric cooling fan or the flow path switching valve has failed.

  Therefore, in the failure diagnosis apparatus according to any one of claims 1 to 8, the failure diagnosis by the failure diagnosis means is performed by the failure diagnosis prohibition means when a stop request for the electric water pump is generated as in claim 9. It is better to ban. In this way, when a stop request for the electric water pump is generated, the failure diagnosis of the electric water pump and the failure diagnosis of the electric cooling fan or the flow path switching valve are prohibited, and the failure diagnosis accuracy decreases. Can be prevented in advance.

  However, in a cooling system equipped with an electric water pump, the electric water pump cannot be stopped despite a request for stopping the electric water pump due to early warming up of the internal combustion engine or the like. There is a possibility that a failure that continues to operate will occur, and if such a failure occurs, the early warm-up of the internal combustion engine will be delayed, and fuel consumption and exhaust emissions will deteriorate.

  Therefore, as in claim 10, when the electric water pump stop request is generated, the difference between the detected outlet water temperature detected by the outlet water temperature sensor and the detected inlet water temperature detected by the inlet water temperature sensor is If the electric water pump cannot be stopped when it is equal to or less than a determination value corresponding to the vehicle operating state, it may be determined that a failure has occurred and continues to operate.

  When the electric water pump is stopped normally and the flow rate of the cooling water decreases, the amount of heat received by the cooling water in the internal combustion engine increases, so the outlet water temperature becomes higher than the inlet water temperature of the internal combustion engine, The difference from the inlet water temperature should be large. Therefore, when a request to stop the electric water pump is generated, when the difference between the detected outlet water temperature detected by the outlet-side water temperature sensor and the detected inlet water temperature detected by the inlet-side water temperature sensor is equal to or smaller than the determination value. Can be determined as the occurrence of a failure in which the electric water pump cannot be stopped and continues to operate.

  Alternatively, as in claim 11, when the change amount of the outlet water temperature detected value detected by the outlet water temperature sensor when the electric water pump stop request is generated is equal to or less than the determination value according to the vehicle operating state In addition, it may be determined that the electric water pump is unable to stop and continues to operate.

  When the electric water pump is normally stopped and the flow rate of the cooling water is reduced, the amount of heat received by the cooling water in the internal combustion engine is increased, so that the outlet water temperature of the internal combustion engine should be increased. Therefore, when a request for stopping the electric water pump is generated, if the amount of change in the outlet water temperature detection value detected by the outlet water temperature sensor is equal to or less than the determination value, the electric water pump cannot be stopped. It can be determined that the failure continues to operate.

  Several embodiments embodying the best mode for carrying out the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine cooling system will be described with reference to FIG.
An electric water pump (hereinafter referred to as “electric W / P”) 12 is provided in the vicinity of the inlet of the cooling water passage (water jacket) of the engine 11 which is an internal combustion engine. The outlet of the cooling water passage of the engine 11 and the inlet of the radiator 13 are connected by a cooling water circulation pipe 14, and the outlet of the radiator 13 and the intake port of the electric W / P 12 are connected by a cooling water circulation pipe 15. As a result, a cooling water circulation circuit 16 in which the cooling water circulates in the path of the cooling water passage of the engine 11 → the cooling water circulation pipe 14 → the radiator 13 → the cooling water circulation pipe 15 → the electric W / P 12 → the cooling water passage of the engine 11 is configured. ing.

  The cooling water circulation circuit 16 is provided with a bypass flow path 17 in parallel with the radiator 13, and both ends of the bypass flow path 17 are connected to the cooling water circulation pipes 14 and 15. A thermostat valve 18 (flow path switching valve) is provided in the vicinity of the connection portion between the bypass flow path 17 and the cooling water circulation pipe 15, and when the cooling water temperature is lower than a predetermined temperature (for example, a temperature corresponding to the completion of warm-up), The thermostat valve 18 is closed to switch to a flow path for circulating the coolant from the engine 11 through the bypass flow path 17, and when the coolant temperature is equal to or higher than a predetermined temperature, the thermostat valve 18 is opened and the engine 11 is switched to a flow path for circulating the coolant from the radiator 11 through the radiator 13. Note that the thermostat valve 18 may include a built-in heater such as a PTC heater that can be opened and closed regardless of the cooling water temperature.

  An electric cooling fan 19 that generates cooling air is disposed in the vicinity of the radiator 13. An inlet-side water temperature sensor 20 that detects a coolant temperature at or near the inlet of the cooling water passage (hereinafter referred to as “inlet water temperature”) is disposed at or near the inlet of the cooling water passage of the engine 11. An outlet-side water temperature sensor 21 that detects a cooling water temperature at or near the outlet of the cooling water passage (hereinafter referred to as “exit water temperature”) is disposed at or near the outlet of the cooling water passage.

  Further, a heating hot water circuit 22 is connected to the cooling water circulation circuit 16 in parallel to the engine 11. A heater core 23 for heating is provided in the middle of the hot water circuit 22, and a heater blower 24 that generates hot air is disposed in the vicinity of the heater core 23.

  The cylinder block of the engine 11 is provided with a crank angle sensor 25 that outputs a pulse signal every time the crankshaft rotates a predetermined crank angle. Based on the output signal of the crank angle sensor 25, the crank angle and the engine rotational speed are attached. Is detected. Further, the intake air amount sensor 26 such as an air flow meter detects the intake air amount, and the vehicle speed sensor 27 detects the vehicle speed.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 28. The ECU 28 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby control a fuel injection valve (not shown) according to the engine operating state. The fuel injection amount and the ignition timing of a spark plug (not shown) are controlled.

  In addition, the ECU 28 executes a water pump control routine (not shown), and refers to the target cooling water temperature map shown in FIG. 2 so that the target cooling water temperature corresponding to the engine operating state (for example, the engine rotation speed and the intake air amount) is obtained. The target flow rate of the cooling water is calculated so that the detected outlet water temperature value detected by the outlet side water temperature sensor 21 matches the target cooling water temperature, and the electric W / P12 is realized so as to realize the target flow rate of the cooling water. To control.

  Further, in the first embodiment, the failure diagnosis routine of FIG. 4 to be described later is executed by the ECU 28, whereby the failure diagnosis of the electric W / P 12 is performed as follows. By calculating the difference between the outlet water temperature detection value detected by the outlet side water temperature sensor 21 and the inlet water temperature detection value detected by the inlet side water temperature sensor 20, the difference between the inlet and outlet water temperature (= exit water temperature detection value−inlet water temperature detection value) The difference between the inlet / outlet water temperature and the failure determination value according to the vehicle operating state is compared to determine whether or not the electric W / P 12 has failed.

  For example, as shown in FIG. 3, when the actual flow rate of the cooling water decreases due to the failure of the electric W / P 12, the time for the cooling water to pass through the engine 11 (the time for the cooling water to receive heat from the engine 11) becomes longer. Since the amount of heat received by the cooling water in the engine 11 increases, the outlet water temperature becomes abnormally high with respect to the inlet water temperature of the engine 11, and the difference between the outlet water temperature and the inlet water temperature becomes abnormally large. On the other hand, even if the heat radiation amount of the cooling water in the radiator 13 changes due to a failure of the electric cooling fan 19 or the like, if the electric W / P 12 operates normally and the cooling water circulates normally, the engine 11 Since the amount of heat received by the cooling water does not change much, the difference between the outlet water temperature of the engine 11 and the inlet water temperature does not change much. Therefore, when the inlet / outlet water temperature difference (= outlet water temperature detected value−inlet water temperature detected value) is equal to or greater than the failure determination value, it can be determined that the electric W / P 12 has failed.

  In addition, if the flow rate of the cooling water decreases due to a failure of the electric W / P 12, the outlet water temperature of the engine 11 becomes abnormally high, so that even when the outlet water temperature detection value is equal to or higher than the upper limit value of the allowable temperature range, It can be determined that a failure has occurred in Formula W / P12.

  The processing contents of the failure diagnosis routine of FIG. 4 executed by the ECU 28 in the first embodiment will be described below. The failure diagnosis routine shown in FIG. 4 is repeatedly executed at a predetermined cycle while the ECU 28 is turned on, and serves as failure diagnosis means in the claims. When this routine is started, first, at step 101, it is determined whether or not a stop request for the electric W / P 12 is generated for the early warming up of the engine 11, and the electric W / P 12 is stopped. When it is determined that the request is generated, the state where the electric W / P 12 is normally stopped in response to the stop request is distinguished from the state where the electric W / P 12 is stopped due to the failure of the electric W / P 12. It is determined that the determination cannot be made separately, and this routine is terminated without performing the processing from step 102 onward. Thereby, failure diagnosis of the electric W / P 12 is prohibited. This function serves as failure diagnosis prohibition means in the claims.

  On the other hand, if it is determined in step 101 that a request for stopping the electric W / P 12 has not occurred, the process proceeds to step 102 where the inlet-side water temperature sensor 20 and the outlet-side water temperature sensor 21 operate normally. Is determined based on the diagnosis result of the self-diagnosis function mounted on the vehicle, and if any failure is detected, the process proceeds to step 103 and the failure of the inlet-side water temperature sensor 20 or the outlet-side water temperature sensor 21 is detected. Determination is made and this routine is terminated.

  On the other hand, if it is confirmed in step 102 that both the inlet-side water temperature sensor 20 and the outlet-side water temperature sensor 21 are normal, processing relating to failure diagnosis after step 104 is executed as follows.

First, in step 104, the difference between the detected outlet water temperature detected by the outlet-side water temperature sensor 21 and the detected inlet water temperature detected by the inlet-side water temperature sensor 20 is calculated to obtain the inlet / outlet water temperature difference.
Inlet / outlet water temperature difference = outlet water temperature detection value-inlet water temperature detection value

  Thereafter, the routine proceeds to step 105, where the heat generation amount of the engine 11 is calculated by a map or a mathematical formula based on the engine operating state (for example, intake air amount or fuel injection amount), and the engine operating state (for example, engine speed and intake air). The target flow rate of the coolant calculated from the target coolant temperature (see FIG. 2) according to the amount) is read, and the amount of heat received by the engine 11 based on the heat generation amount of the engine 11 and the target flow rate of the coolant. The estimated value is calculated by a map or a mathematical formula. In addition, since the amount of heat radiation of the engine 11 changes according to the vehicle speed (running wind) and the outside air temperature, and the amount of cooling water received by the engine 11 changes, the cooling water in the engine 11 changes according to the vehicle speed and the outside air temperature. The estimated amount of heat received may be corrected.

  Thereafter, the process proceeds to step 106, where the cooling water temperature of the engine 11 is determined based on the estimated amount of heat received by the cooling water in the engine 11, the target flow rate of the cooling water, and the physical properties of the cooling water (for example, specific heat and density). After calculating (estimating) the increase, the process proceeds to step 107, and a value slightly larger than the estimated value of the increase in the coolant temperature in the engine 11 is set as the failure determination value. By these processes in steps 105 to 107, a failure determination value corresponding to the vehicle operating state (engine speed, intake air amount, vehicle speed, outside temperature, etc.) is set.

  Thereafter, the process proceeds to step 108, where it is determined whether the inlet / outlet water temperature difference (= exit water temperature detected value−inlet water temperature detected value) is equal to or greater than the failure determination value. As a result, if it is determined that the water temperature difference at the inlet / outlet is equal to or greater than the failure determination value, the routine proceeds to step 110, where it is determined that a failure has occurred in the electric W / P 12, and processing at the time of failure is performed. Exit. In the processing at the time of failure, for example, the failure flag is set to ON and the warning lamp 29 provided on the driver's seat instrument panel is turned on, or the warning display section (not shown) of the driver's seat instrument panel is shown. The warning information is displayed to the driver, and the abnormality information (abnormality code, etc.) is stored in the rewritable nonvolatile memory (not shown) of the ECU 28 such as the backup RAM (not shown), and the stored data is retained even when the ECU 28 is turned off. Stored in a rewritable memory.

  On the other hand, if it is determined in step 108 that the inlet / outlet water temperature difference is smaller than the failure determination value, the process proceeds to step 109, and whether or not the detected outlet water temperature value detected by the outlet-side water temperature sensor 21 is equal to or greater than a predetermined value. Determine whether. This predetermined value may be set to a preset fixed value (for example, a value slightly higher than the maximum value of the target cooling water temperature), or the engine operating state (for example, engine speed and intake air amount). You may set to the value a little higher than the target cooling water temperature according to.

  If it is determined in step 110 that the outlet water temperature detection value is equal to or greater than the predetermined value, the process proceeds to step 110, where it is determined that the electric W / P 12 has failed, and processing at the time of failure is performed. This routine ends.

  On the other hand, if it is determined in step 108 that the inlet / outlet water temperature difference is smaller than the failure determination value, and it is determined in step 109 that the outlet water temperature detection value is lower than the predetermined value, step 111 is performed. Then, it is determined that there is no failure (normal) of the electric W / P 12, and this routine is terminated.

  In the first embodiment described above, when the flow rate of the cooling water decreases due to the failure of the electric W / P 12, the amount of heat received by the cooling water in the engine 11 increases, so the difference between the outlet water temperature of the engine 11 and the inlet water temperature. Note that the difference between the outlet water temperature of the engine 11 and the inlet water temperature does not change much even if the amount of heat dissipated in the radiator 13 changes due to a failure of the electric cooling fan 19 or the like. Thus, the electric W / P 12 malfunctions by comparing the inlet / outlet water temperature difference (the difference between the detected outlet water temperature detected by the outlet water temperature sensor 21 and the detected inlet water temperature detected by the inlet water temperature sensor 20) with the failure determination value. Therefore, the failure diagnosis accuracy of the electric W / P 12 can be improved.

  In addition, since the failure determination value according to the vehicle operating state is used, the amount of cooling water received by the engine 11 changes according to the vehicle operating state, and the difference between the outlet water temperature and the inlet water temperature changes. Correspondingly, the failure determination value can be changed to set the failure determination value to an appropriate value, and the failure diagnosis accuracy of the electric W / P 12 can be further improved.

  In the first embodiment, when it is determined that a stop request for the electric W / P 12 is generated, the electric W / P 12 is normally stopped in accordance with the stop request, Since it is determined that it is not possible to distinguish and determine the state stopped due to the failure of the expression W / P12 and the failure diagnosis of the electric W / P12 is prohibited, the failure diagnosis of the electric W / P12 is performed. A decrease in accuracy can be prevented in advance.

  In the first embodiment, the difference between the outlet water temperature detection value and the inlet water temperature detection value is compared with the failure determination value to determine whether or not the electric W / P 12 has failed. The presence / absence of a failure in the electric W / P 12 may be determined by comparing the ratio with the detected inlet water temperature with the failure determination value.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the ECU 28 executes a failure diagnosis routine of FIG. 6 to be described later, so that the difference between the detected outlet water temperature detected by the outlet water temperature sensor 21 and the detected inlet water temperature detected by the inlet water temperature sensor 20 is different. The actual amount of cooling water received by the engine 11 is calculated based on the (inlet / outlet water temperature difference), and the amount of cooling water received by the engine 11 based on the calorific value obtained from the engine operating state and the target flow rate of the cooling water. An estimated value is calculated, and the difference between the actual amount of heat received from the cooling water and the estimated amount of heat received from the cooling water is compared with a predetermined failure determination value to determine whether or not the electric W / P 12 has failed.

  For example, as shown in FIG. 5, when the actual flow rate of the cooling water decreases due to a failure of the electric W / P 12, the difference between the outlet water temperature and the inlet water temperature of the engine 11 becomes abnormally large. The actual heat received by the cooling water becomes abnormally large. Therefore, when the difference between the actual amount of heat received by the cooling water and the estimated amount of heat received by the cooling water is equal to or greater than the failure determination value, it can be determined that the electric W / P 12 has failed.

  Hereinafter, processing contents of the failure diagnosis routine of FIG. 6 executed by the ECU 28 in the second embodiment will be described. In the failure diagnosis routine shown in FIG. 6, if it is determined in step 201 that a request for stopping the electric W / P 12 is generated, the failure diagnosis of the electric W / P 12 is prohibited. On the other hand, if it is determined that the stop request for the electric W / P 12 has not occurred, it is confirmed in the next step 202 that both the inlet side water temperature sensor 20 and the outlet side water temperature sensor 21 are normal. Then, the process related to the failure diagnosis after step 204 is executed as follows.

  First, in step 204, the difference between the detected outlet water temperature detected by the outlet-side water temperature sensor 21 and the detected inlet water temperature detected by the inlet-side water temperature sensor 20 is calculated to obtain the inlet / outlet water temperature difference. Based on the temperature difference, the target flow rate of the cooling water, and the physical properties of the cooling water (for example, specific heat and density), the actual amount of heat received by the cooling water in the engine 11 is calculated using a map or a mathematical expression. The processing in step 204 serves as actual heat receiving amount calculation means in the claims.

  Thereafter, the process proceeds to step 205, where the heat generation amount of the engine 11 is calculated based on the engine operating state (for example, intake air amount or fuel injection amount) by a map or a mathematical formula, and the heat generation amount of the engine 11 and the target flow rate of the cooling water. Based on the above, the estimated amount of heat received by the cooling water in the engine 11 is calculated by a map or a mathematical expression. In addition, you may make it correct | amend the heat receiving amount estimated value of the cooling water in the engine 11 according to a vehicle speed or external temperature. The process of step 205 plays a role as a heat receiving amount estimation means in the claims.

  Thereafter, the process proceeds to step 206, in which it is determined whether or not the absolute value of the difference between the actual amount of heat received by the cooling water and the estimated amount of heat received by the cooling water is equal to or greater than the failure determination value. As a result, when it is determined that the absolute value of the difference between the actual amount of heat received from the cooling water and the estimated amount of heat received from the cooling water is greater than or equal to the failure determination value, the process proceeds to step 207 and a failure of the electric W / P 12 occurs. After determining that it has occurred and performing processing at the time of failure, this routine is terminated.

  On the other hand, if it is determined in step 206 that the absolute value of the difference between the actual amount of heat received from the cooling water and the estimated amount of heat received from the cooling water is smaller than the failure determination value, the process proceeds to step 208. It is determined that there is no failure (normal) in the electric W / P 12, and this routine is terminated.

  In the second embodiment described above, the difference between the outlet water temperature and the inlet water temperature of the engine 11 becomes abnormally large when the actual flow rate of the cooling water is reduced due to the failure of the electric W / P 12, and therefore, the difference is obtained from the inlet / outlet water temperature difference. Focusing on the fact that the actual amount of heat received by the cooling water becomes abnormally large, the difference between the actual amount of heat received by the cooling water and the estimated amount of heat received by the cooling water is compared with the failure judgment value, and the failure of the electric W / P 12 Since the presence / absence is determined, the failure diagnosis accuracy of the electric W / P 12 can be improved.

  In Example 2, the difference between the actual amount of heat received from the cooling water and the estimated amount of heat received from the cooling water is compared with the failure determination value to determine whether or not the electric W / P 12 has failed. The ratio between the actual amount of heat received by the cooling water and the estimated amount of heat received by the cooling water may be compared with the failure determination value to determine whether or not the electric W / P 12 has failed.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the third embodiment, the ECU 28 executes a failure diagnosis routine of FIG. 8 to be described later, thereby estimating the amount of heat received by the cooling water in the engine 11 based on the heat generation amount obtained from the engine operating state and the target flow rate of the cooling water. The outlet water temperature estimated value is calculated based on the inlet water temperature detected value detected by the inlet water temperature sensor 20 and the received heat amount estimation value of the cooling water, and the outlet water temperature detected value detected by the outlet water temperature sensor 21 is calculated. Is compared with a predetermined failure determination value to determine whether or not the electric W / P 12 has failed.

  For example, as shown in FIG. 7, when the actual flow rate of the cooling water decreases due to a failure of the electric W / P 12, the outlet water temperature of the engine 11 becomes abnormally high, and the outlet water temperature detection value detected by the outlet side water temperature sensor 21 Becomes abnormally high. Therefore, when the difference between the detected outlet water temperature value and the estimated outlet water temperature value is equal to or greater than the failure determination value, it can be determined that the electric W / P 12 has failed.

  Hereinafter, the processing content of the failure diagnosis routine of FIG. 8 executed by the ECU 28 in the third embodiment will be described. In the failure diagnosis routine shown in FIG. 8, if it is determined in step 301 that a request for stopping the electric W / P 12 is generated, the failure diagnosis of the electric W / P 12 is prohibited. On the other hand, if it is determined that the stop request for the electric W / P 12 has not occurred, it is confirmed in the next step 302 that both the inlet side water temperature sensor 20 and the outlet side water temperature sensor 21 are normal. Then, the process related to the failure diagnosis after step 304 is executed as follows.

  First, in step 304, the heat generation amount of the engine 11 is calculated based on the engine operating state (for example, the intake air amount or the fuel injection amount) by a map or a mathematical formula, and the heat generation amount of the engine 11 and the target flow rate of the cooling water are set. Based on this, the estimated amount of heat received by the cooling water in the engine 11 is calculated using a map or mathematical formula. In addition, you may make it correct | amend the heat receiving amount estimated value of the cooling water in the engine 11 according to a vehicle speed or external temperature.

  Thereafter, the process proceeds to step 305, where the cooling water temperature of the engine 11 is determined based on the estimated amount of heat received by the cooling water in the engine 11, the target flow rate of the cooling water, and the physical properties of the cooling water (for example, specific heat and density). Calculate (estimate) the increase.

Thereafter, the process proceeds to step 306, where an estimated value of the outlet water temperature is obtained by adding the amount of increase in the cooling water temperature at the engine 11 to the detected inlet water temperature value detected by the inlet-side water temperature sensor 20.
Estimated outlet water temperature = Detected inlet water temperature + Amount of increase in cooling water temperature The processes in these steps 305 and 306 serve as outlet water temperature estimating means in the claims.

  Thereafter, the process proceeds to step 307, in which it is determined whether or not the absolute value of the difference between the detected outlet water temperature value detected by the outlet-side water temperature sensor 21 and the estimated outlet water temperature is equal to or greater than the failure determination value. As a result, when it is determined that the absolute value of the difference between the detected outlet water temperature value and the estimated outlet water temperature is equal to or greater than the failure determination value, the process proceeds to step 308 to determine that the electric W / P 12 has failed. After performing the process at the time of failure, this routine is terminated.

  On the other hand, if it is determined in step 307 that the absolute value of the difference between the detected outlet water temperature value and the estimated outlet water temperature value is smaller than the failure determination value, the process proceeds to step 309 and the electric W / P 12 It is determined that there is no failure (normal), and this routine is terminated.

  In the third embodiment described above, when the actual flow rate of the cooling water decreases due to the failure of the electric W / P 12, the outlet water temperature of the engine 11 becomes abnormally high, and the outlet water temperature detection value detected by the outlet side water temperature sensor 21. Since the difference between the outlet water temperature detection value and the outlet water temperature estimated value is compared with the failure determination value, it is determined whether or not the electric W / P 12 has failed. It is possible to improve the failure diagnosis accuracy of W / P12.

  In the third embodiment, the difference between the detected outlet water temperature and the estimated outlet water temperature is compared with the failure determination value to determine whether or not the electric W / P 12 has failed. The presence / absence of a failure of the electric W / P 12 may be determined by comparing the ratio with the estimated outlet water temperature with a failure determination value.

  Next, Embodiment 4 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the fourth embodiment, the ECU 28 executes a failure diagnosis routine shown in FIG. 10 to be described later, thereby estimating the amount of received heat of the cooling water in the engine 11 based on the heat generation amount obtained from the engine operating state and the target flow rate of the cooling water. The inlet water temperature estimated value is calculated based on the outlet water temperature detected value detected by the outlet side water temperature sensor 21 and the estimated amount of heat received by the cooling water, and the inlet water temperature estimated value and the inlet side water temperature sensor 20 calculate the value. The difference between the detected inlet water temperature detection value and a predetermined failure determination value is compared to determine whether or not the electric W / P 12 has failed.

  For example, as shown in FIG. 9, when the actual flow rate of the cooling water decreases due to the failure of the electric W / P 12, the outlet water temperature of the engine 11 becomes abnormally high, and the outlet water temperature detection value detected by the outlet side water temperature sensor 21. Therefore, the estimated inlet water temperature obtained from the detected outlet water temperature and the estimated amount of heat received from the cooling water becomes abnormally high. Therefore, when the difference between the estimated inlet water temperature and the detected inlet water temperature is equal to or greater than the failure determination value, it can be determined that the electric W / P 12 has failed.

  Hereinafter, processing contents of the failure diagnosis routine of FIG. 10 executed by the ECU 28 in the fourth embodiment will be described. In the failure diagnosis routine shown in FIG. 10, if it is determined in step 401 that a request for stopping the electric W / P 12 is generated, the failure diagnosis of the electric W / P 12 is prohibited. On the other hand, if it is determined that the stop request for the electric W / P 12 has not occurred, it is confirmed in the next step 402 that both the inlet side water temperature sensor 20 and the outlet side water temperature sensor 21 are normal. Then, the process regarding the fault diagnosis after step 404 is executed as follows.

  First, in step 404, the heat generation amount of the engine 11 is calculated based on the engine operating state (for example, the intake air amount or the fuel injection amount) by a map or a mathematical formula, and the heat generation amount of the engine 11 and the target flow rate of the cooling water are set. Based on this, the estimated amount of heat received by the cooling water in the engine 11 is calculated using a map or mathematical formula. In addition, you may make it correct | amend the heat receiving amount estimated value of the cooling water in the engine 11 according to a vehicle speed or external temperature.

  Thereafter, the process proceeds to step 405, where the cooling water temperature of the engine 11 is determined based on the estimated amount of heat received by the cooling water in the engine 11, the target flow rate of the cooling water, and the physical properties of the cooling water (for example, specific heat and density). Calculate (estimate) the increase.

Thereafter, the process proceeds to step 406, and an estimated inlet water temperature value is obtained by subtracting the amount of increase in the cooling water temperature at the engine 11 from the detected outlet water temperature value detected by the outlet side water temperature sensor 21.
Estimated inlet water temperature = Detected outlet water temperature-Increased cooling water temperature The processes in steps 405 and 406 serve as inlet water temperature estimating means in the claims.

  Thereafter, the process proceeds to step 407, and it is determined whether or not the absolute value of the difference between the estimated inlet water temperature value and the detected inlet water temperature value detected by the inlet-side water temperature sensor 20 is equal to or greater than the failure determination value. As a result, if it is determined that the absolute value of the difference between the estimated inlet water temperature value and the detected inlet water temperature is equal to or greater than the failure determination value, the process proceeds to step 408, where it is determined that the electric W / P 12 has failed. After performing the process at the time of failure, this routine is terminated.

  On the other hand, if it is determined in step 407 that the absolute value of the difference between the estimated inlet water temperature value and the detected inlet water temperature value is smaller than the failure determination value, the process proceeds to step 409 and the electric W / P 12 It is determined that there is no failure (normal), and this routine is terminated.

  In the fourth embodiment described above, when the actual flow rate of the cooling water decreases due to the failure of the electric W / P 12, the outlet water temperature of the engine 11 becomes abnormally high, and the outlet water temperature detection value detected by the outlet side water temperature sensor 21. Note that the difference between the estimated inlet water temperature and the detected inlet water temperature is notable because the estimated inlet water temperature obtained from the detected outlet water temperature and the estimated amount of heat received from the cooling water is abnormally high. Is compared with the failure determination value to determine whether or not there is a failure in the electric W / P 12. Therefore, the failure diagnosis accuracy of the electric W / P 12 can be improved.

  In the fourth embodiment, the difference between the estimated inlet water temperature and the detected inlet water temperature is compared with the failure determination value to determine whether or not the electric W / P 12 has failed. The presence / absence of a failure in the electric W / P 12 may be determined by comparing the ratio with the detected inlet water temperature with the failure determination value.

  Next, Embodiment 5 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the fifth embodiment, the ECU 28 executes a failure diagnosis routine shown in FIG. 12 to be described later, thereby determining factors that determine the heat dissipation amount of the cooling water in the radiator 13 (for example, the vehicle speed, the target rotational speed of the electric cooling fan 19, Based on the outlet water temperature detection value detected by the outlet side water temperature sensor 21 and the cooling water heat release amount estimated value. The estimated inlet water temperature is calculated, and the difference between the detected inlet water temperature detected by the inlet-side water temperature sensor 20 and the estimated inlet water temperature is compared with a predetermined failure judgment value, so that the electric cooling fan 19 or the thermostat valve 18 fails. The presence or absence of is determined.

  For example, as shown in FIG. 11, when the flow rate of cooling air decreases due to a failure of the electric cooling fan 19 or the flow rate of cooling water circulating to the radiator 13 decreases due to a failure of the thermostat valve 18, the radiator 13. The amount of heat dissipated in the cooling water is reduced, so that the inlet temperature of the engine 11 becomes abnormally high, and the detected inlet water temperature detected by the inlet-side water temperature sensor 20 becomes abnormally high. Therefore, when the difference between the detected inlet water temperature value and the estimated inlet water temperature is equal to or greater than the failure determination value, it can be determined that the electric cooling fan 19 or the thermostat valve 18 has failed.

  Hereinafter, processing contents of the failure diagnosis routine of FIG. 12 executed by the ECU 28 in the fifth embodiment will be described. In the failure diagnosis routine shown in FIG. 12, it is determined in step 501 whether or not a request for stopping the electric W / P 12 is generated, and it is determined that a request for stopping the electric W / P 12 is generated. When the electric W / P 12 is stopped and the circulation of the cooling water is stopped, the amount of heat dissipated in the cooling water in the radiator 13 is reduced, and the radiator 13 is damaged by the failure of the electric cooling fan 19 or the thermostat valve 18. Therefore, it is determined that it is difficult to accurately determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed, because the amount of heat radiation of the cooling water is reduced. By ending this routine without performing the subsequent processing, failure diagnosis of the electric cooling fan 19 and the thermostat valve 18 is prohibited. This function serves as failure diagnosis prohibition means in the claims.

  On the other hand, if it is determined in step 501 that a stop request for the electric W / P 12 has not been generated, both the inlet side water temperature sensor 20 and the outlet side water temperature sensor 21 are normal in the next step 502. If it is confirmed, the process proceeds to step 503, where it is determined whether or not the electric W / P 12 is normal based on the failure diagnosis result of the electric W / P 12, and any failure has been detected. If it is determined that the electric W / P 12 has failed, the routine is terminated.

On the other hand, if it is confirmed in step 503 that the electric W / P 12 is normal, processing relating to failure diagnosis after step 505 is executed as follows.
First, in step 505, a map or a mathematical expression is used to estimate the cooling water heat release amount in the radiator 13 based on the vehicle speed, the target rotational speed of the electric cooling fan 19, the target flow rate of the cooling water, the detected outlet water temperature, the outside air temperature, and the like. Etc. are calculated. The processing in step 505 serves as heat radiation amount estimation means in the claims.

  Thereafter, the process proceeds to step 506, where the cooling water temperature of the radiator 13 is determined based on the estimated heat dissipation amount of the cooling water in the radiator 13, the target flow rate of the cooling water, and the physical properties of the cooling water (for example, specific heat and density). Calculate (estimate) the amount of descent.

Thereafter, the process proceeds to step 507, and the estimated inlet water temperature is obtained by subtracting the cooling water temperature drop at the radiator 13 from the detected outlet water temperature detected by the outlet-side water temperature sensor 21.
Estimated inlet water temperature = outlet water temperature detected value-decrease in cooling water temperature The processing of these steps 506 and 507 serves as the inlet water temperature estimating means in the claims.

  Thereafter, the process proceeds to step 508, and it is determined whether or not the absolute value of the difference between the detected inlet water temperature value detected by the inlet-side water temperature sensor 20 and the estimated inlet water temperature is equal to or greater than the failure determination value. As a result, if it is determined that the absolute value of the difference between the detected inlet water temperature value and the estimated inlet water temperature is equal to or greater than the failure determination value, the process proceeds to step 509, where a failure of the electric cooling fan 19 or the thermostat valve 18 occurs. This routine is terminated after the process is determined and the process at the time of failure is performed.

  On the other hand, if it is determined in step 508 that the absolute value of the difference between the detected inlet water temperature value and the estimated inlet water temperature value is smaller than the failure determination value, the process proceeds to step 510 and the electric cooling fan 19 Then, it is determined that there is no failure (normal) in the thermostat valve 18, and this routine is terminated.

  In the fifth embodiment described above, if the actual cooling air flow rate decreases due to the failure of the electric cooling fan 19 or the flow rate of the cooling water circulating to the radiator 13 decreases due to the failure of the thermostat valve 18, the radiator. Since the heat radiation amount of the cooling water at 13 decreases, the inlet temperature of the engine 11 becomes abnormally high, and the inlet water temperature detection value detected by the inlet water temperature sensor 20 becomes abnormally high. Since the difference between the detected value and the estimated inlet water temperature is compared with the failure determination value to determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed, the electric cooling fan 19 or the thermostat valve 18 has failed. Diagnosis accuracy can be improved.

  Further, in the fifth embodiment, when it is determined that a request for stopping the electric W / P 12 is generated, when the electric W / P 12 stops and the circulation of the cooling water stops, the radiator 13 Since the heat radiation amount of the cooling water is reduced and a state similar to the state where the heat radiation amount of the cooling water in the radiator 13 is reduced due to the failure of the electric cooling fan 19 or the thermostat valve 18, the electric cooling fan 19 and the thermostat valve 18 are judged to be difficult to determine accurately, and the failure diagnosis of the electric cooling fan 19 and the thermostat valve 18 is prohibited. It is possible to prevent the failure diagnosis accuracy of the thermostat valve 18 from being lowered.

  In the fifth embodiment, the difference between the detected inlet water temperature and the estimated inlet water temperature is compared with the failure determination value to determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed. The ratio between the detected water temperature value and the estimated inlet water temperature value may be compared with a failure determination value to determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed.

  Next, Embodiment 6 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as in the fifth embodiment will be omitted or simplified, and different parts from the fifth embodiment will be mainly described.

  In the sixth embodiment, the ECU 28 executes a failure diagnosis routine shown in FIG. 14 to be described later, thereby determining factors that determine the heat radiation amount of the cooling water in the radiator 13 (for example, the vehicle speed, the target rotational speed of the electric cooling fan 19, The estimated amount of heat radiation of the cooling water in the radiator 13 is calculated based on the target flow rate of the cooling water, and the outlet water temperature detected by the outlet water temperature sensor 21 and the inlet water temperature detected by the inlet water temperature sensor 20 Based on the difference (inlet / outlet water temperature difference) from the detected value, the actual heat dissipation amount of the cooling water in the radiator 13 is calculated, and the difference between the estimated heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water is determined as a predetermined failure. Compared with the determination value, it is determined whether or not the electric cooling fan 19 or the thermostat valve 18 has failed.

  For example, as shown in FIG. 13, when the flow rate of the cooling air decreases due to a failure of the electric cooling fan 19 or the flow rate of the cooling water circulating to the radiator 13 decreases due to the failure of the thermostat valve 18, the radiator 13. Therefore, the actual heat dissipation amount of the cooling water at the radiator 13 obtained from the inlet / outlet water temperature difference becomes abnormally small. Therefore, when the difference between the estimated heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water is equal to or greater than the failure determination value, it can be determined that the electric cooling fan 19 or the thermostat valve 18 has failed.

  Hereinafter, processing contents of the failure diagnosis routine of FIG. 14 executed by the ECU 28 in the sixth embodiment will be described. In the failure diagnosis routine shown in FIG. 14, if it is determined in step 601 that a request for stopping the electric W / P 12 has occurred, failure diagnosis of the electric cooling fan 19 and the thermostat valve 18 is prohibited. On the other hand, if it is determined that the stop request for the electric W / P 12 has not occurred, it is confirmed in the next step 602 that both the inlet side water temperature sensor 20 and the outlet side water temperature sensor 21 are normal. Further, in the next step 603, if it is confirmed that the electric W / P 12 is normal, processing relating to failure diagnosis after step 505 is executed as follows.

  First, in step 605, a map or a mathematical formula is used to calculate the estimated heat dissipation amount of the cooling water in the radiator 13 based on the vehicle speed, the target rotational speed of the electric cooling fan 19, the target flow rate of the cooling water, the detected outlet water temperature, the outside air temperature and the like. Etc. are calculated.

  Thereafter, the process proceeds to step 606, where the difference between the outlet water temperature detected value detected by the outlet side water temperature sensor 21 and the inlet water temperature detected value detected by the inlet side water temperature sensor 20 is calculated to obtain the inlet / outlet water temperature difference, Based on the inlet / outlet water temperature difference, the target flow rate of the cooling water, and the physical property values (for example, specific heat and density) of the cooling water, the actual heat dissipation amount of the cooling water in the radiator 13 is calculated by a map or a mathematical expression. The processing in step 606 serves as the actual heat radiation amount calculation means in the claims.

  Thereafter, the process proceeds to step 607, in which it is determined whether or not the absolute value of the difference between the estimated heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water is equal to or greater than the failure determination value. As a result, if it is determined that the absolute value of the difference between the estimated heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water is greater than or equal to the failure determination value, the process proceeds to step 608 and the electric cooling fan 19 or thermostat. After determining that a failure has occurred in the valve 18 and performing processing at the time of failure, this routine is terminated.

  On the other hand, if it is determined in step 607 that the absolute value of the difference between the estimated heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water is smaller than the failure determination value, the process proceeds to step 609. It is determined that there is no failure (normal) in the electric cooling fan 19 and the thermostat valve 18, and this routine is terminated.

  In the sixth embodiment described above, when the actual cooling air flow rate decreases due to the failure of the electric cooling fan 19 or when the flow rate of the cooling water circulating to the radiator 13 decreases due to the failure of the thermostat valve 18, the radiator. Since the amount of heat radiation of the cooling water at 13 decreases, the actual heat radiation amount of the cooling water at the radiator 13 obtained from the inlet / outlet water temperature difference becomes abnormally small. The difference between the actual heat radiation amount and the failure determination value is compared to determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed. Therefore, the failure diagnosis accuracy of the electric cooling fan 19 or the thermostat valve 18 is improved. Can be improved.

  In the sixth embodiment, the difference between the estimated value of the heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water is compared with the failure determination value to determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed. However, the ratio of the estimated heat dissipation amount of the cooling water and the actual heat dissipation amount of the cooling water may be compared with the failure determination value to determine whether or not the electric cooling fan 19 or the thermostat valve 18 has failed. .

  Next, Embodiment 7 of the present invention will be described with reference to FIGS. 15 and 16. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the engine cooling system equipped with the electric W / P 12, the electric W / P 12 is activated even though a stop request for the electric W / P 12 is generated for the purpose of early warming up of the engine 11. If such a failure occurs, the early warm-up of the engine 11 is delayed, and fuel consumption and exhaust emission are deteriorated.

  In the seventh embodiment, therefore, the ECU 28 executes a failure diagnosis routine shown in FIG. 16 to be described later, and when the electric W / P 12 stop request is generated as shown in FIG. By calculating the difference between the detected outlet water temperature detected by the sensor 21 and the detected inlet water temperature detected by the inlet-side water temperature sensor 20, an inlet / outlet water temperature difference (= outlet water temperature detected value−inlet water temperature detected value) is obtained. When this inlet / outlet water temperature difference is equal to or less than a determination value corresponding to the vehicle operating state, it is determined that a failure has occurred in which the electric W / P 12 cannot be stopped and continues to operate.

  When the electric W / P 12 is normally stopped and the flow rate of the cooling water decreases, the amount of cooling water received by the engine 11 increases, so the outlet water temperature becomes higher than the inlet water temperature of the engine 11, and the outlet water temperature The difference between the water temperature and the inlet water temperature should be large. Therefore, when the electric W / P12 stop request is generated, if the inlet / outlet water temperature difference (= the outlet water temperature detected value−the inlet water temperature detected value) is equal to or smaller than the determination value, the electric W / P12 cannot be stopped. Thus, it can be determined that the failure has continued to operate.

  Hereinafter, processing contents of the failure diagnosis routine of FIG. 16 executed by the ECU 28 in the seventh embodiment will be described. In the failure diagnosis routine shown in FIG. 16, first, at step 701, it is determined whether or not a stop request for the electric W / P 12 has been generated for the purpose of early warming up of the engine 11, etc. If it is determined that a stop request has not occurred, this routine is terminated without performing the processing from step 702 onward.

  On the other hand, if it is determined in step 701 that a request for stopping the electric W / P 12 has occurred, the process proceeds to step 702, where the inlet-side water temperature sensor 20 and the outlet-side water temperature sensor 21 operate normally. Is determined based on the diagnosis result of the self-diagnosis function mounted on the vehicle, and if any failure is detected, the process proceeds to step 703, where the failure of the inlet side water temperature sensor 20 or the outlet side water temperature sensor 21 is detected. Determination is made and this routine is terminated.

  On the other hand, if it is confirmed in step 702 that both the inlet-side water temperature sensor 20 and the outlet-side water temperature sensor 21 are normal, processing relating to failure diagnosis after step 704 is executed as follows.

  First, in step 704, the difference between the detected outlet water temperature detected by the outlet-side water temperature sensor 21 and the detected inlet water temperature detected by the inlet-side water temperature sensor 20 is calculated to obtain the inlet / outlet water temperature difference.

  Thereafter, the process proceeds to step 705, where the heat generation amount of the engine 11 is calculated by a map or a mathematical formula based on the engine operating state (for example, the intake air amount or the fuel injection amount), and the engine 11 is calculated based on the heat generation amount of the engine 11. The estimated amount of heat received by the cooling water is calculated using a map or mathematical formula. In addition, you may make it correct | amend the heat receiving amount estimated value of the cooling water in the engine 11 according to a vehicle speed or external temperature.

  Thereafter, the process proceeds to step 706, and the amount of increase in the cooling water temperature in the engine 11 is calculated (estimated) based on the estimated amount of heat received by the cooling water in the engine 11 and the physical property values (for example, specific heat and density) of the cooling water. After that, the process proceeds to step 707, and an increase in the coolant temperature in the engine 11 or a value slightly smaller than that is set as a failure determination value.

  Thereafter, the process proceeds to step 708, where it is determined whether the inlet / outlet water temperature difference (= the outlet water temperature detected value−the inlet water temperature detected value) is equal to or smaller than a determination value. As a result, when it is determined that the inlet / outlet water temperature difference is equal to or less than the determination value, the process proceeds to step 709, where it is determined that a failure has occurred and the electric W / P 12 cannot be stopped and continues to operate, and processing at the time of the failure After this, this routine is finished.

  On the other hand, if it is determined in step 708 that the inlet / outlet water temperature difference is larger than the determination value, the process proceeds to step 710 and there is no failure of the electric W / P 12 (the electric W / P 12 is requested to stop). Accordingly, the routine is terminated.

  In the seventh embodiment described above, when a request for stopping the electric W / P 12 is generated, if the water temperature difference at the inlet / outlet is equal to or less than the determination value, the electric W / P 12 cannot be stopped and continues to operate. Since it has been determined that a failure has occurred, it is possible to detect a failure in which the electric W / P 12 is unable to stop and continues to operate despite a request to stop the electric W / P 12.

  Next, Embodiment 8 of the present invention will be described with reference to FIGS. However, description of the substantially same parts as those of the seventh embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the eighth embodiment, the ECU 28 executes a failure diagnosis routine shown in FIG. 18 to be described later, and as shown in FIG. 17, when the stop request for the electric W / P 12 is generated, the outlet side water temperature sensor 21. When the change amount of the outlet water temperature detection value detected in step S1 is equal to or less than the determination value corresponding to the vehicle operating state, it is determined that a failure has occurred and the electric W / P 12 cannot be stopped and continues to operate.

  When the electric W / P 12 is normally stopped and the flow rate of the cooling water is decreased, the amount of heat received by the cooling water in the engine 11 is increased, so that the outlet water temperature of the engine 11 should be increased. Therefore, when a request for stopping the electric W / P 12 is generated, if the amount of change in the detected outlet water temperature detected by the outlet-side water temperature sensor 21 is equal to or less than the determination value, the electric W / P 12 cannot be stopped. Therefore, it can be determined that a failure has occurred and continues to operate.

  Hereinafter, the processing contents of the failure diagnosis routine of FIG. 18 executed by the ECU 28 in the eighth embodiment will be described. In the failure diagnosis routine shown in FIG. 18, when it is determined in step 801 that a stop request for the electric W / P 12 is generated, in the next step 802, the inlet-side water temperature sensor 20 and the outlet-side water temperature sensor 21. If both are confirmed to be normal, processing relating to failure diagnosis after step 804 is executed as follows.

First, in step 804, the amount of change per unit time of the outlet water temperature detection value detected by the outlet side water temperature sensor 21 is calculated.
Thereafter, the process proceeds to step 805, where the heat generation amount of the engine 11 is calculated by a map or a mathematical formula based on the engine operating state (for example, the intake air amount or the fuel injection amount), and the engine 11 based on the heat generation amount of the engine 11 The estimated amount of heat received by the cooling water is calculated using a map or mathematical formula. In addition, you may make it correct | amend the heat receiving amount estimated value of the cooling water in the engine 11 according to a vehicle speed or external temperature.

  Thereafter, the process proceeds to step 806, where the estimated amount of change in the outlet water temperature per unit time is calculated based on the estimated amount of heat received by the cooling water in the engine 11 and the physical properties of the cooling water (for example, specific heat and density). Thereafter, the process proceeds to step 807, where the estimated change amount per unit time of the outlet water temperature or a value slightly smaller than that is set as the failure determination value.

  Thereafter, the process proceeds to step 808, and it is determined whether or not the amount of change in the outlet water temperature detection value per unit time is equal to or less than the determination value. As a result, if it is determined that the amount of change in the outlet water temperature detection value per unit time is equal to or less than the determination value, the process proceeds to step 809, where a failure occurs where the electric W / P 12 cannot be stopped and continues to operate. After determining and performing the process at the time of failure, this routine is terminated.

  On the other hand, if it is determined in step 808 that the amount of change in the outlet water temperature detection value per unit time is larger than the determination value, the process proceeds to step 810, and there is no failure of the electric W / P 12 (electric It is determined that the expression W / P12 is normally stopped in response to the stop request), and this routine is finished.

  In the eighth embodiment described above, when a request for stopping the electric W / P 12 is generated, the electric W / P 12 is operating when the change amount of the outlet water temperature detection value is equal to or less than the determination value. Since it has been determined that a failure has occurred, it is possible to detect a failure in which the electric W / P 12 is unable to stop and continues to operate despite a request to stop the electric W / P 12. .

  In each of the first to eighth embodiments, the present invention is applied to a cooling system in which the thermostat valve 18 is provided in the cooling water circulation circuit 16. However, instead of the thermostat valve 18, a flow path switching valve constituted by an electromagnetic valve is used. The present invention may be applied to a provided cooling system.

  In addition, the present invention can be implemented with various modifications within a range that does not depart from the gist, such as appropriately changing the configuration of the cooling system.

It is a schematic block diagram of the whole engine cooling system in Example 1 of this invention. It is a figure which shows notionally an example of the map of target cooling water temperature. 6 is a time chart for explaining an execution example of failure diagnosis according to the first embodiment. 6 is a flowchart for explaining a flow of processing of a failure diagnosis routine according to the first embodiment. 6 is a time chart for explaining an execution example of failure diagnosis according to the second embodiment. 6 is a flowchart for explaining a flow of processing of a failure diagnosis routine of a second embodiment. 12 is a time chart for explaining an execution example of failure diagnosis of the third embodiment. 10 is a flowchart for explaining a flow of processing of a failure diagnosis routine of a third embodiment. 10 is a time chart for explaining an execution example of failure diagnosis according to a fourth embodiment. 10 is a flowchart for explaining a flow of processing of a failure diagnosis routine of a fourth embodiment. 10 is a time chart for explaining an execution example of failure diagnosis of Embodiment 5. 10 is a flowchart for explaining a flow of processing of a failure diagnosis routine of the fifth embodiment. 12 is a time chart for explaining an execution example of failure diagnosis according to the sixth embodiment. 12 is a flowchart for explaining a flow of processing of a failure diagnosis routine of a sixth embodiment. 12 is a time chart for explaining an execution example of failure diagnosis of Example 7. 12 is a flowchart for explaining a processing flow of a failure diagnosis routine according to the seventh embodiment. 10 is a time chart for explaining an execution example of failure diagnosis of an eighth embodiment. 10 is a flowchart for explaining a flow of processing of a failure diagnosis routine of an eighth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Electric W / P, 13 ... Radiator, 16 ... Cooling water circulation circuit, 18 ... Thermostat valve (flow-path switching valve), 19 ... Electric cooling fan, 20 ... Inlet side water temperature sensor , 21... Outlet side water temperature sensor, 28... ECU (failure diagnosis means, actual heat reception amount calculation means, heat reception amount estimation means, outlet water temperature estimation means, inlet water temperature estimation means, heat release amount estimation means, actual heat release amount calculation means, failure diagnosis Prohibited means)

Claims (11)

In a failure diagnosis device for a vehicle cooling system comprising an electric water pump for circulating cooling water between an internal combustion engine and a radiator,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
The difference or ratio between the outlet water temperature detection value detected by the outlet side water temperature sensor and the inlet water temperature detection value detected by the inlet side water temperature sensor is compared with a failure determination value according to the vehicle operating state, and the electric water pump A failure diagnosis device for a vehicle cooling system, comprising: failure diagnosis means for determining presence or absence of failure.   2. The failure diagnosis unit determines that the electric water pump has failed when a difference between the detected outlet water temperature value and the detected inlet water temperature value is equal to or greater than the failure determination value. Fault diagnosis device for vehicle cooling system.   3. The vehicle cooling system according to claim 1, wherein the failure diagnosis unit includes a unit that determines that a failure has occurred in the electric water pump when the detected outlet water temperature value is equal to or greater than a predetermined value. 4. Fault diagnosis device. In a failure diagnosis device for a vehicle cooling system comprising an electric water pump for circulating cooling water between an internal combustion engine and a radiator,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
An actual heat receiving amount calculation means for calculating an actual heat receiving amount of the cooling water in the internal combustion engine based on a difference between the detected outlet water temperature value detected by the outlet side water temperature sensor and the detected inlet water temperature value by the inlet side water temperature sensor. When,
A heat receiving amount estimating means for estimating a heat receiving amount of the cooling water in the internal combustion engine based on a heat generation amount obtained from an operating state of the internal combustion engine and a target flow rate of the cooling water;
Failure diagnosis for determining whether or not there is a failure in the electric water pump by comparing the actual received amount of cooling water calculated by the actual received heat amount calculating means and the estimated received amount of cooling water estimated by the received heat amount estimating means And a failure diagnosis device for a vehicle cooling system. In a failure diagnosis device for a vehicle cooling system comprising an electric water pump for circulating cooling water between an internal combustion engine and a radiator,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
A heat receiving amount estimating means for estimating a heat receiving amount of the cooling water in the internal combustion engine based on a heat generation amount obtained from an operating state of the internal combustion engine and a target flow rate of the cooling water;
Outlet water temperature estimating means for estimating the outlet water temperature based on the inlet water temperature detected value detected by the inlet water temperature sensor and the received heat amount estimated value of the cooling water estimated by the received heat amount estimating means;
A failure diagnosing unit that compares the detected outlet water temperature detected by the outlet-side water temperature sensor with the estimated outlet water temperature estimated by the outlet water temperature estimating unit to determine whether or not the electric water pump has failed. A failure diagnosis apparatus for a cooling system for a vehicle. In a failure diagnosis device for a vehicle cooling system comprising an electric water pump for circulating cooling water between an internal combustion engine and a radiator,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
A heat receiving amount estimating means for estimating a heat receiving amount of the cooling water in the internal combustion engine based on a heat generation amount obtained from an operating state of the internal combustion engine and a target flow rate of the cooling water;
An inlet water temperature estimating means for estimating the inlet water temperature based on the outlet water temperature detected value detected by the outlet water temperature sensor and the received heat amount estimated value of the cooling water estimated by the received heat amount estimating means;
A failure diagnostic means for comparing the detected inlet water temperature detected by the inlet water temperature sensor with the estimated inlet water temperature estimated by the inlet water temperature estimating means to determine whether or not the electric water pump has failed. A failure diagnosis apparatus for a cooling system for a vehicle. An electric water pump that circulates cooling water between the internal combustion engine and the radiator, an electric cooling fan that generates cooling air for the radiator, a flow path that circulates the cooling water in the radiator, and cooling water in the radiator In a failure diagnosis apparatus for a cooling system for a vehicle having a flow path switching valve that switches between bypass flow paths that are not circulated,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
A heat radiation amount estimating means for estimating a heat radiation amount of the cooling water in the radiator based on a factor for determining a heat radiation amount of the cooling water in the radiator;
Inlet water temperature estimation means for estimating the inlet water temperature based on the outlet water temperature detection value detected by the outlet water temperature sensor and the heat radiation amount estimation value of the cooling water estimated by the heat radiation amount estimation means;
Failure diagnosis that compares the detected inlet water temperature detected by the inlet-side water temperature sensor with the estimated inlet water temperature estimated by the inlet water temperature estimating means to determine whether the electric cooling fan or the flow path switching valve is defective. And a failure diagnosis device for a vehicle cooling system. An electric water pump that circulates cooling water between the internal combustion engine and the radiator, an electric cooling fan that generates cooling air for the radiator, a flow path that circulates the cooling water in the radiator, and cooling water in the radiator In a failure diagnosis apparatus for a cooling system for a vehicle having a flow path switching valve that switches between bypass flow paths that are not circulated,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
An actual heat release amount calculating means for calculating an actual heat release amount of the cooling water in the radiator based on a difference between an outlet water temperature detection value detected by the outlet side water temperature sensor and an inlet water temperature detection value detected by the inlet side water temperature sensor; ,
A heat radiation amount estimating means for estimating a heat radiation amount of the cooling water in the radiator based on a factor for determining a heat radiation amount of the cooling water in the radiator;
Comparing the actual heat dissipation amount of the cooling water calculated by the actual heat dissipation amount calculating means and the estimated heat dissipation amount of the cooling water estimated by the heat dissipation amount estimating means, the failure of the electric cooling fan or the flow path switching valve A failure diagnosis device for a vehicle cooling system, comprising: failure diagnosis means for determining presence or absence.   9. The vehicle according to claim 1, further comprising failure diagnosis prohibiting means for prohibiting failure diagnosis by the failure diagnosis means when a request for stopping the electric water pump is generated. Failure diagnosis device for cooling system In a failure diagnosis device for a vehicle cooling system comprising an electric water pump for circulating cooling water between an internal combustion engine and a radiator,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
The difference between the detected outlet water temperature detected by the outlet-side water temperature sensor and the detected inlet water temperature detected by the inlet-side water temperature sensor when a stop request for the electric water pump is generated depends on the vehicle operating condition. A failure diagnosis device for a cooling system for a vehicle, comprising: failure diagnosis means for determining that a failure has occurred in which the electric water pump cannot be stopped and continues to operate when the value is less than a determination value. In a failure diagnosis device for a vehicle cooling system comprising an electric water pump for circulating cooling water between an internal combustion engine and a radiator,
An inlet side water temperature sensor for detecting a cooling water temperature at or near the cooling water inlet of the internal combustion engine (hereinafter referred to as "inlet water temperature");
An outlet side water temperature sensor for detecting a cooling water outlet of the internal combustion engine or a cooling water temperature in the vicinity thereof (hereinafter referred to as “outlet water temperature”);
The electric water pump is stopped when the change amount of the outlet water temperature detected value detected by the outlet side water temperature sensor is equal to or less than a determination value according to the vehicle operating state when the electric water pump stop request is generated. A failure diagnosis device for a vehicle cooling system, comprising: failure diagnosis means for determining that a failure has occurred and continues to operate.

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