JP2015059458A - Control device for cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve failure diagnosis accuracy of a cooling system.SOLUTION: In a normal operation state in which change in a rotational speed and a load of an internal combustion engine, a vehicle speed and outside air in a diagnostic period over predetermined time are in a predetermined range (S5-S8), by determining whether or not deviation of diagnosis start water temperature STW and diagnosis end water temperature FTW during the diagnostic period is equal to or less than a predetermined threshold value TWJD1 (S4, S9 and S10), it is determined whether failure has occurred in a cooling system of the internal combustion engine. Such diagnosis is executed after completion of warming-up at which time a cooling water temperature is stabilized, that is, in a state where cooling water is introduced in a radiator (S2), and also, in a state where a radiator fan juxtaposed in the radiator is being operated at which time influence of vehicle travel wind is reduced (S3).

Description

  The present invention relates to a control device for a cooling system (cooling device) mounted on a vehicle.

  In a cooling system that cools an internal combustion engine mounted on a vehicle, for example, when a failure occurs in an electric water pump that circulates cooling water, the internal combustion engine may overheat. For this reason, as described in JP 2009-74430 A (Patent Document 1), according to the temperature change of the cooling water accompanying the operation and stop of the electric water pump, the radiator fan, and the thermostat during operation of the internal combustion engine, Techniques for diagnosing cooling system failures have been proposed.

JP 2009-74430 A

  However, in the technique proposed in Patent Document 1, the operating state of the vehicle and the internal combustion engine when diagnosing a failure is not defined. For example, the operating state of the internal combustion engine changes during the failure diagnosis and the cooling water When the temperature changes, there is a risk that the failure diagnosis accuracy may be lowered, such as diagnosis that a failure has occurred even though no failure has occurred.

  Therefore, an object of the present invention is to provide a cooling system control device that improves the failure diagnosis accuracy of the cooling system.

  For this reason, the control device for the cooling system changes the temperature of the cooling water in a state where the internal combustion engine is in steady operation and the electric water pump that circulates the cooling water to the cooling system of the internal combustion engine is driven and controlled. Accordingly, it is diagnosed whether a failure has occurred in the cooling system.

  According to the present invention, failure diagnosis is not executed when the internal combustion engine is in a transient operation state, so that the failure diagnosis accuracy of the cooling system can be improved.

It is a schematic diagram showing an example of a cooling system of an internal combustion engine. It is a flowchart which shows 1st Example of the failure diagnosis process of a cooling system. It is a time chart which shows a state change when the 1st Example of failure diagnosis processing is performed. It is a flowchart which shows 2nd Example of the failure diagnosis process of a cooling system. It is a flowchart which shows 2nd Example of the failure diagnosis process of a cooling system. It is a time chart which shows a state change when 2nd Example of failure diagnosis processing is performed.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a cooling system for an internal combustion engine mounted on a vehicle.

  The cooling water that has cooled the cylinder block 12 and the cylinder head 14 of the internal combustion engine 10 is guided through the first cooling water passage 16 to a radiator 20 provided with an electric radiator fan 18 (electric fan). The cooling water guided to the radiator 20 exchanges heat with the outside air when passing through the radiator core to which the fins are attached, and the temperature of the cooling water decreases. Then, the cooling water whose temperature has been lowered by passing through the radiator 20 is returned to the internal combustion engine 10 via the second cooling water passage 22.

  Further, the first cooling water passage 16 and the second cooling water passage 22 are connected to each other via a bypass passage 24 so that the cooling water discharged from the internal combustion engine 10 bypasses the radiator 20. In the second cooling water passage 22, upstream of the joint portion of the bypass passage 24, for example, a wax type thermostat 26 is provided that switches the cooling water flow path according to the cooling water temperature (cooling water temperature). ing. The thermostat 26 promotes warm-up so that the coolant discharged from the internal combustion engine 10 is not supplied to the radiator 20 during warm-up when the coolant temperature is equal to or lower than a predetermined temperature. In addition, the thermostat 26 allows the cooling water discharged from the internal combustion engine 10 to be supplied to the radiator 20 after the warm-up in which the cooling water temperature is higher than the predetermined temperature, so that the predetermined cooling performance can be exhibited. The thermostat 26 may be disposed downstream of the joint portion of the bypass passage 24 in the first cooling water passage 16.

  An electric water pump 28 that forcibly circulates the cooling water between the internal combustion engine 10 and the radiator 20 is disposed downstream of the junction of the bypass passage 24 in the second cooling water passage 22. The electric water pump 28 is driven by, for example, a brushless motor as a drive source different from the internal combustion engine 10 so that the cooling performance can be exhibited even when the internal combustion engine 10 is stopped by the idle stop function.

  As a control system for controlling the driving of the radiator fan 18 and the electric water pump 28, a predetermined temperature of the vehicle is provided with a water temperature sensor 30 for detecting the coolant temperature Tw of the coolant discharged from the internal combustion engine 10, and the rotation of the internal combustion engine 10. A rotation speed sensor 32 for detecting the speed Ne, a load sensor 34 for detecting the load Tp of the internal combustion engine 10, a vehicle speed sensor 36 for detecting the vehicle speed VSP, and an outside air temperature sensor 38 for detecting the outside air temperature OSTMP are attached. Here, as the load Tp of the internal combustion engine 10, for example, a state quantity closely related to the torque of the internal combustion engine 10 such as an intake air flow rate, an intake negative pressure, a supercharging pressure, a fuel injection amount, an accelerator opening degree, a throttle opening degree, and the like. Is applicable. The output signals of the water temperature sensor 30, the rotational speed sensor 32, the load sensor 34, the vehicle speed sensor 36, and the outside air temperature sensor 38 are input to a control device 40 incorporating a microcomputer.

  Then, the control device 40 diagnoses whether or not a failure has occurred in the cooling system of the internal combustion engine 10 according to a control program stored in a nonvolatile memory such as a flash ROM (Read Only Memory), and the radiator fan 18. And the electric water pump 28 is electronically controlled. Here, the control device 40 sets the target cooling water temperature according to the operating state of the internal combustion engine 10 and controls the discharge amount of the electric water pump 28 so that the actual cooling water temperature approaches the target cooling water temperature. .

  It should be noted that the determination unit and the diagnosis unit can be realized by the control device 40 executing the control program. Further, at least one of the coolant temperature Tw, the rotational speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP is obtained from another control device connected via an in-vehicle network such as a CAN (Controller Area Network). You may make it read.

  FIG. 2 shows a first embodiment of a cooling system failure diagnosis process executed by the control device 40 when an ignition switch (not shown) is turned on. Here, it is assumed that control for turning on (driving) the electric water pump 28 is performed as a premise for executing the failure diagnosis process of the cooling system (the same applies hereinafter). The failure diagnosis process for the cooling system is executed once when the ignition switch is turned on, but may be repeatedly executed every predetermined time. In this way, it is possible to diagnose a failure that has occurred during one driving cycle.

  In step 1 (abbreviated as “S1” in FIG. 2, the same applies hereinafter), the control device 40 determines whether or not the water temperature sensor 30 and the radiator fan 18 are normal, that is, whether or not a failure has occurred in these. Determine whether. Here, whether or not a failure has occurred in the water temperature sensor 30 and the radiator fan 18 may be determined by using a self-diagnosis function built in the water temperature sensor 30 and the radiator fan 18 or its control system, for example. If the controller 40 determines that the water temperature sensor 30 and the radiator fan 18 are normal, the control device 40 proceeds to step 2 (Yes), while determining that at least one of the water temperature sensor 30 and the radiator fan 18 is not normal. If this is the case, the failure diagnosis process for the cooling system is terminated (No). That is, if at least one of the water temperature sensor 30 and the radiator fan 18 has failed, it cannot be diagnosed whether or not a failure has occurred in the cooling system of the internal combustion engine 10, so that the diagnosis process is not executed. If at least one of the water temperature sensor 30 and the radiator fan 18 has a failure, for example, a warning light, a buzzer, or the like can be operated to notify the vehicle driver to that effect.

  In step 2, the control device 40 determines whether or not the cooling water is being passed through the radiator 20 based on the cooling water temperature Tw read from the water temperature sensor 30, in other words, whether or not the warm-up has been completed. To do. That is, when the cooling water temperature becomes higher than the predetermined temperature, the thermostat 26 is operated and the cooling water is supplied to the radiator 20. Therefore, the control device 40 determines whether or not the cooling water temperature Tw is higher than the predetermined temperature. It is determined whether or not cooling water is being passed through the radiator 20. The control device 40 advances the process to step 3 if it is determined that cooling water is being passed through the radiator 20 (Yes), while it is warm if it is determined that cooling water is not being passed through the radiator 20. Wait until the machine is complete (No). In this way, the failure diagnosis process for the cooling system is not executed while the internal combustion engine 10 is warmed up. For example, the failure diagnosis is not performed when the cooling water temperature is unstable, and the deterioration of the diagnosis accuracy is suppressed. can do.

  In step 3, the control device 40 always turns on the radiator fan 18 regardless of the level of the coolant temperature Tw. In this way, since the cooling air is supplied to the radiator 20 by the radiator fan 18, it is possible to reduce the influence of the traveling wind of the vehicle, for example.

  In step 4, the control device 40 reads the cooling water temperature Tw from the water temperature sensor 30, and stores it as a diagnosis start water temperature STW in a volatile memory such as a RAM (Random Access Memory).

  In step 5, the control device 40 reads the rotational speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP from the rotation speed sensor 32, the load sensor 34, the vehicle speed sensor 36, and the outside air temperature sensor 38, respectively. Then, the control device 40 uses the rotation speed Ne, the load Tp, the vehicle speed VSP, and the outside temperature OSTMP read from each sensor as the diagnosis start rotation speed SNe, the diagnosis start load STp, the diagnosis start vehicle speed SVSP, and the diagnosis start outside temperature SOSTMP. Each is stored in a volatile memory.

  In Step 6, the control device 40 determines whether or not a predetermined time, which is a period for determining whether or not a steady operation state has elapsed, after storing the diagnosis start rotational speed SNe and the like. Here, for example, a time counting function provided in the control device 40 can be used to determine whether or not the predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the control device 40 proceeds to step 7 (Yes), while if it is determined that the predetermined time has not elapsed, the control device 40 waits until the predetermined time has elapsed (No).

  In step 7, the control device 40 reads the rotational speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP from the rotation speed sensor 32, the load sensor 34, the vehicle speed sensor 36, and the outside air temperature sensor 38, respectively. Then, the control device 40 uses the rotation speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP read from each sensor as the diagnosis end rotation speed FNe, the diagnosis end load FTp, the diagnosis end vehicle speed FVSP, and the diagnosis end outside air temperature FOSTMP. Each is stored in a volatile memory.

In step 8, the control device 40 performs the diagnosis start rotational speed SNe, the diagnosis start load STp, the diagnosis start vehicle speed SVSP, the diagnosis start outside temperature SOSTMP, the diagnosis end rotation speed FNe, the diagnosis end load FTp, the diagnosis end vehicle speed FVSP, and the diagnosis end out. Based on the temperature FOSTMP, it is determined whether or not the vehicle and the internal combustion engine 10 are in a steady operation state. Specifically, the control device 40 determines whether or not all of the following four conditions are satisfied. | X | indicates the absolute value of x.
(1) | FNe-SNe | ≦ NeJDG
(2) | FTp−STp | ≦ TpJDG
(3) | FVSP-SVSP | ≦ VSPJDG
(4) | FOSTMP-SOSTMP | ≦ OSTMPJDG

  Here, NeJDG, TpJDG, VSPJDG, and OSTMPJDG are the steady operation through whether the rotational speed Ne, load Tp, vehicle speed VSP, and outside air temperature OSTMP at the start and end of diagnosis are within predetermined ranges, respectively. It is a threshold value for determining whether or not it is in a state. These threshold values can be appropriately set through, for example, experiments and simulations in consideration of the characteristics of the vehicle and the internal combustion engine 10. If it is determined that the control device 40 is in the steady operation state, the process proceeds to step 9 (Yes), but if the control device 40 determines that it is not the steady operation state, that is, the transient operation state, the process proceeds to step 4. (No).

  In step 9, the control device 40 reads the cooling water temperature Tw from the water temperature sensor 30, and stores it in the volatile memory as the diagnosis end water temperature FTW.

  In Step 10, whether or not the absolute value of the value obtained by subtracting the diagnosis start water temperature STW from the diagnosis end water temperature FTW is equal to or less than a predetermined threshold TWJDG1, specifically, | FTW−STW | ≦ TWJDG1 It is determined whether the condition is satisfied. Here, the predetermined threshold value TWJDG1 is determined in view of the fact that if the failure of the cooling system of the internal combustion engine 10 has not occurred, the predetermined cooling performance is exhibited by the radiator 20 and the cooling water temperature is maintained substantially constant. It is a threshold value for determining the presence or absence of occurrence. For this reason, the predetermined threshold value TWJDG1 can be appropriately set in consideration of the cooling performance of the radiator 20, for example. If it is determined that the condition is satisfied, the control device 40 proceeds to step 11 (Yes), whereas if it is determined that the condition is not satisfied, the process proceeds to step 13 (No). ).

  In step 11, the control device 40 diagnoses that the cooling system of the internal combustion engine 10 is normal. Specifically, the control device 40 is free from cracks in the first cooling water passage 16, the second cooling water passage 22, and the bypass passage 24 through which the cooling water circulates. It is diagnosed that a failure such as disconnection has not occurred in the electric water pump 28 that has not occurred.

  In step 12, the control device 40 returns the radiator fan 18 to normal operation, that is, normal operation in which the rotational speed of the radiator fan 18 is changed in accordance with the coolant temperature Tw.

  In step 13, since a failure has occurred in the cooling system of the internal combustion engine 10, the control device 40 shifts to a fail-safe mode that limits the torque of the internal combustion engine 10. In the fail-safe mode, for example, the fuel injection amount can be limited and / or the intake air amount can be limited. In this way, the torque of the internal combustion engine 10 decreases and the amount of heat generation decreases, so that the temperature increase of the internal combustion engine 10 can be suppressed.

  Note that a series of processes from Step 5 to Step 8 is given as an example of the determining means, and a series of processes from Step 4, Step 9 and Step 10 is given as an example of the diagnostic means.

  According to the first embodiment of the failure diagnosis process for the cooling system, as shown in FIG. 3, the diagnosis start point and the diagnosis in the diagnosis period over a predetermined time with the radiator fan 18 and the electric water pump 28 operated. A diagnosis start water temperature STW and a diagnosis end water temperature FTW at the end time are detected, respectively. Then, whether or not a failure has occurred in the cooling system of the internal combustion engine 10 is diagnosed according to the deviation between the diagnosis end water temperature FTW and the diagnosis start water temperature STW, that is, the temperature change of the cooling water.

  When a failure has not occurred in the cooling system of the internal combustion engine 10, a predetermined cooling performance is exhibited by the radiator 20. Therefore, the cooling water temperature has converged to the target cooling water temperature, and a diagnosis period over a predetermined time period. The temperature change of the cooling water is small. On the other hand, when a failure has occurred in the cooling system of the internal combustion engine 10, the radiator 20 cannot exert a predetermined cooling performance, so that the temperature change of the cooling water in the diagnosis period over a predetermined time is large. If the deviation between the diagnosis end water temperature FTW and the diagnosis start water temperature STW is larger than a predetermined threshold TWJDG1 using such a temperature change characteristic of the cooling water, the cooling system of the internal combustion engine 10, for example, the cooling water is forcibly circulated. It can be diagnosed that a failure has occurred in the electric water pump 28 to be operated.

  In the process of performing a failure diagnosis of the cooling system, when the rotational speed Ne and the load Tp, the vehicle speed VSP and the outside air temperature OSTMP of the internal combustion engine 10 are within the predetermined ranges, in other words, the rotational speed Ne and the load Tp, the vehicle speed VSP and the outside air temperature OSTMP. The diagnosis start water temperature STW and the diagnosis end water temperature FTW are detected in a steady operation state in which the change in the difference is small. For this reason, failure diagnosis in a transient operation state in which the operation states of the vehicle and the internal combustion engine 10 change can be avoided, and a factor that lowers the failure diagnosis accuracy can be eliminated. Accordingly, the failure diagnosis accuracy of the cooling system can be improved.

  Here, as the steady operation state, it is possible to apply a condition that the coolant temperature in the cooling system is substantially constant, that the vehicle is stopped and the internal combustion engine 10 is idling. In this case, the threshold NeJDG of the condition (1) may be set to the idling fluctuation range, and the threshold VSPJDG of the condition (3) may be set to 0. In this way, since the failure diagnosis of the cooling system is executed under the condition that the cooling water temperature is substantially constant, the failure diagnosis accuracy can be further improved. The same applies to the second embodiment of the cooling system failure diagnosis process described below.

  4 and 5 show a second embodiment of the cooling system failure diagnosis process executed by the control device 40 when the ignition switch is turned on. In addition, about the process similar to the above 1st Example, the description is simplified in order to eliminate duplication description. If necessary, refer to the description of the first embodiment.

  In step 21, the control device 40 determines whether or not the water temperature sensor 30 and the radiator fan 18 are normal. If the controller 40 determines that the water temperature sensor 30 and the radiator fan 18 are normal, the control device 40 proceeds to step 22 (Yes), while determining that at least one of the water temperature sensor 30 and the radiator fan 18 is not normal. If this is the case, the failure diagnosis process for the cooling system is terminated (No).

  In step 22, the control device 40 determines whether or not cooling water is being passed through the radiator 20 based on the cooling water temperature Tw read from the water temperature sensor 30. Then, if it is determined that the cooling water is being passed through the radiator 20, the control device 40 proceeds to step 23 (Yes), while if it is determined that the cooling water is not being passed through the radiator 20, the control device 40 is warmed up. Wait until the machine is complete (No).

In step 23, the control device 40 always turns on the radiator fan 18.
In step 24, the control device 40 turns off the electric water pump 28. If it does in this way, since cooling water will not circulate through the cooling system of internal-combustion engine 10, and predetermined cooling performance by radiator 20 will not be demonstrated, the cooling water temperature in a cooling system will rise gradually over time.

  In step 25, the control device 40 determines whether or not a first predetermined time has elapsed since the electric water pump 28 was turned off. Here, the first predetermined time is a time for raising the cooling water temperature in the cooling system to some extent, and can be set according to, for example, the heat generation characteristics of the internal combustion engine 10 and the cooling performance of the radiator 20. If it is determined that the first predetermined time has elapsed, the control device 40 proceeds to step 26 (Yes), while if it is determined that the first predetermined time has not elapsed, the first predetermined time has elapsed. (No).

  In step 26, the control device 40 reads the cooling water temperature Tw from the water temperature sensor 30, and stores it in the nonvolatile memory as the diagnosis start water temperature STW.

  In step 27, the control device 40 turns on the electric water pump 28 whose operation was stopped in step 24.

  In step 28, the control device 40 reads the rotational speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP from the rotational speed sensor 32, the load sensor 34, the vehicle speed sensor 36, and the outside air temperature sensor 38, respectively. Then, the control device 40 uses the rotation speed Ne, the load Tp, the vehicle speed VSP, and the outside temperature OSTMP read from each sensor as the diagnosis start rotation speed SNe, the diagnosis start load STp, the diagnosis start vehicle speed SVSP, and the diagnosis start outside temperature SOSTMP. Each is stored in a volatile memory.

  In step 29, the control device 40 determines whether or not a second predetermined time has elapsed after storing the diagnosis start rotational speed SNe and the like. Here, the second predetermined time has the same technical significance as the predetermined time in the first embodiment. If it is determined that the second predetermined time has elapsed, the control device 40 proceeds to step 30 (Yes), whereas if it is determined that the second predetermined time has not elapsed, the second predetermined time has elapsed. (No).

  In step 30, the control device 40 reads the rotational speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP from the rotation speed sensor 32, the load sensor 34, the vehicle speed sensor 36, and the outside air temperature sensor 38, respectively. Then, the control device 40 uses the rotation speed Ne, the load Tp, the vehicle speed VSP, and the outside air temperature OSTMP read from each sensor as the diagnosis end rotation speed FNe, the diagnosis end load FTp, the diagnosis end vehicle speed FVSP, and the diagnosis end outside air temperature FOSTMP. Each is stored in a volatile memory.

  In step 31, the control device 40 performs the diagnosis start rotational speed SNe, the diagnosis start load STp, the diagnosis start vehicle speed SVSP, the diagnosis start outside temperature SOSTMP, the diagnosis end rotation speed FNe, the diagnosis end load FTp, the diagnosis end vehicle speed FVSP, and the diagnosis end out. Based on the temperature FOSTMP, it is determined whether or not the vehicle and the internal combustion engine 10 are in a steady operation state. And if it judges with it being in a steady operation state, control device 40 will advance processing to Step 32 (Yes), but will return processing to Step 26, if it judges with it not being in a steady operation state (No).

  In step 32, the control device 40 reads the cooling water temperature Tw from the water temperature sensor 30 and stores it in the volatile memory as the diagnosis end water temperature FTW.

  In step 33, the control device 40 determines whether or not the absolute value of the value obtained by subtracting the diagnosis end water temperature FTW from the diagnosis start water temperature STW is equal to or greater than a predetermined threshold value TWJDG2. Here, the predetermined threshold value TWJDG2 indicates that a failure has occurred in view of the fact that a predetermined cooling performance is exhibited by the radiator 20 and the cooling water temperature gradually decreases unless a failure occurs in the cooling system of the internal combustion engine 10. This is a threshold for determining the presence or absence. For this reason, the predetermined threshold value TWJDG2 can be appropriately set in consideration of, for example, the cooling performance of the radiator 20. If it is determined that the condition is satisfied, the control device 40 proceeds to step 34 (Yes), whereas if it is determined that the condition is not satisfied, the process proceeds to step 36 (No). ).

In step 34, the control device 40 diagnoses that the cooling system of the internal combustion engine 10 is normal.
In step 35, the control device 40 returns the radiator fan 18 to normal operation.

  In step 36, since a failure has occurred in the cooling system of the internal combustion engine 10, the control device 40 shifts to a fail-safe mode that limits the torque of the internal combustion engine 10.

  Note that a series of processes from step 28 to step 31 is given as an example of a determination unit, and a series of processes from step 24 to step 27, step 32, and step 33 is given as an example of a diagnostic unit.

  According to the second embodiment of the failure diagnosis process for the cooling system, as shown in FIG. 6, the electric water pump 28 is stopped for a first predetermined time while the radiator fan 18 is operated. If it does in this way, since cooling water does not circulate through the cooling system of internal-combustion engine 10, cooling water temperature Tw in a cooling system rises. Further, when the electric water pump 28 is restarted, that is, the diagnosis start water temperature STW at the diagnosis start time in the diagnosis period over the second predetermined time and the diagnosis end water temperature FTW at the diagnosis end time in the diagnosis period are detected. Is done. Then, whether or not a failure has occurred in the cooling system of the internal combustion engine 10 is diagnosed in accordance with the deviation between the diagnosis start water temperature STW and the diagnosis end water temperature FTW, that is, the temperature change of the cooling water.

  When a failure has not occurred in the cooling system of the internal combustion engine 10, the radiator 20 exhibits a predetermined cooling performance, so that the electric water pump 28 is temporarily stopped during the diagnosis period over the second predetermined time. The cooled cooling water temperature gradually decreases toward the target cooling water temperature. On the other hand, when a failure has occurred in the cooling system of the internal combustion engine 10, the radiator 20 cannot exert a predetermined cooling performance, so that the electric water pump 28 is temporarily stopped during the second predetermined period of time. Increased cooling water temperature does not decrease easily. Using such a temperature change characteristic of the cooling water, if the deviation between the diagnosis start water temperature STW and the diagnosis end water temperature FTW is less than a predetermined threshold TWJDG2, it is diagnosed that a failure has occurred in the cooling system of the internal combustion engine 10. Can do.

  Since other operations and effects are the same as those in the first embodiment, description thereof will be omitted. Please refer to the appropriate explanation if necessary.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder block 14 Cylinder head 16 1st cooling water path 22 2nd cooling water path 24 Bypass path 26 Thermostat 28 Electric water pump 30 Water temperature sensor 32 Rotation speed sensor 34 Load sensor 36 Vehicle speed sensor 38 Outside temperature sensor 40 Control device

Claims (3)

Determining means for determining whether the internal combustion engine is in steady operation;
In the state where the internal combustion engine is in steady operation and the electric water pump that circulates the cooling water to the cooling system of the internal combustion engine is driven and controlled, the cooling system fails due to the temperature change of the cooling water Diagnostic means for diagnosing whether or not
A control device for a cooling system, comprising: The diagnosis means, the temperature of the cooling water when the electric water pump is stopped for a first predetermined time, the driving of the electric water pump is restarted, the temperature of the cooling water after the elapse of a second predetermined time, Diagnosing whether a failure has occurred in the cooling system based on
The control device for a cooling system according to claim 1. The determination means determines that the internal combustion engine is in steady operation when the vehicle is stopped and the internal combustion engine is idling.
The control device for a cooling system according to claim 1 or 2, wherein the control device is a cooling system.