US20150152775A1 - Cooling device for internal combustion engine - Google Patents

Cooling device for internal combustion engine Download PDF

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Publication number
US20150152775A1
US20150152775A1 US14/534,477 US201414534477A US2015152775A1 US 20150152775 A1 US20150152775 A1 US 20150152775A1 US 201414534477 A US201414534477 A US 201414534477A US 2015152775 A1 US2015152775 A1 US 2015152775A1
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United States
Prior art keywords
coolant water
internal combustion
combustion engine
engine
thermostat valve
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Abandoned
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US14/534,477
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English (en)
Inventor
Ikuo Ando
Hitoki Sugimoto
Toshitake Sasaki
Yoshihisa Oda
Kenji Kimura
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Toyota Motor Corp
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Toyota Motor Corp
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Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA reassignment TOYOTA JIDOSHA KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ANDO, IKUO, KIMURA, KENJI, ODA, YOSHIHISA, SASAKI, TOSHITAKE, SUGIMOTO, HITOKI
Publication of US20150152775A1 publication Critical patent/US20150152775A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F01P7/165—Controlling of coolant flow the coolant being liquid by thermostatic control characterised by systems with two or more loops
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/08—Temperature
    • F01P2025/32—Engine outcoming fluid temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2025/00—Measuring
    • F01P2025/08—Temperature
    • F01P2025/34—Heat exchanger incoming fluid temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2060/00—Cooling circuits using auxiliaries
    • F01P2060/08—Cabin heater
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P2060/00—Cooling circuits using auxiliaries
    • F01P2060/18—Heater

Definitions

  • the present invention relates to a cooling device for an internal combustion engine, and particularly to a technique of diagnosing a failure of a thermostat valve provided in a cooling device for an internal combustion engine.
  • Japanese Patent Laying-Open No. 2010-196587 discloses an abnormality detecting device for detecting an abnormality of a thermostat valve provided in an engine cooling system of a hybrid vehicle capable of performing EV traveling of stopping an engine and traveling with a drive force of a motor. An increase in the EV traveling reduces an opportunity to operate an engine and in turn reduces an opportunity to detect an abnormality of a thermostat valve. According to this abnormality detecting device, engine coolant water is heated by a heater during the EV traveling, and if a temperature of the engine coolant water rises to be higher than or equal to a determination temperature, it is determined that a thermostat valve operates normally (Japanese Patent Laying Open No. 2010-196587).
  • Heat of coolant water heated by exhausted heat of an engine can be utilized for heating or the like performed by an air-conditioning device, and even during stopping of the engine, circulation of coolant water by operation of an electric pump in accordance with a heating request or the like of the air-conditioning device may occur.
  • the thermostat valve since the engine is stopped, the thermostat valve is closed, and the coolant water circulates without passing through a radiator. Accordingly, a situation may occur which causes the temperature of the circulating coolant water to be lower than a temperature of coolant water remaining in a radiator circulation passage for allowing coolant water to flow into the radiator.
  • the present invention was made to solve the problem described above, and its object is to suppress erroneous determination in a failure diagnosis for a thermostat valve provided in a cooling device for an internal combustion engine.
  • a cooling device for an internal combustion engine includes a coolant water passage formed in the internal combustion engine, a radiator cooling coolant water, a radiator circulation passage, a bypass passage, a heat exchanger, a thermostat valve, an electric pump, first and second temperature sensors, and a control device.
  • the radiator circulation passage is configured to allow coolant water discharged from the coolant water passage to pass through the radiator and return to the coolant water passage.
  • the bypass passage is configured to allow coolant water discharged from the coolant water passage to return to the coolant water passage without passing through the radiator.
  • the heat exchanger is provided on the bypass passage and utilizes heat of the coolant water.
  • the thermostat valve is connected to the radiator circulation passage and the bypass passage, and switched, in accordance with a temperature of coolant water flowing in the thermostat valve, to either a closed state of intercepting coolant water from the radiator circulation passage and outputting coolant water from the bypass passage to the coolant water passage, or an opened state of outputting coolant water from the radiator circulation passage and coolant water from the bypass passage to the coolant water passage.
  • the electric pump allows coolant water to circulate.
  • the first temperature sensor detects a temperature of coolant water in the coolant water passage.
  • the second temperature sensor detects a temperature of coolant water in the radiator circulation passage.
  • the control device performs a failure diagnosis for the thermostat valve after starting of the internal combustion engine based on an output of the first temperature sensor and an output of the second temperature sensor.
  • the thermostat valve attains the closed state.
  • the control device delays starting of the failure diagnosis performed after starting of the internal combustion engine as compared to a case where the electric pump does not operate during stopping of the internal combustion engine.
  • this cooling device for an internal combustion engine in the case where the electric pump operates in accordance with the operation request of the heat exchanger during stopping of the internal combustion engine, starting of the failure diagnosis performed after starting of the internal combustion engine is delayed as compared to the case where the electric pump does not operate during stopping of the internal combustion engine. Therefore, starting of the failure diagnosis for the thermostat valve is avoided in a state where the relationship between the temperature of the coolant water in the coolant water passage and the temperature of the coolant water in the radiator circulation passage are inversed. Thus, according to the cooling device for an internal combustion engine, erroneous determination in the failure diagnosis for the thermostat valve can be suppressed.
  • the control device starts the failure diagnosis when a rise quantity ( ⁇ ECT) of a coolant water temperature, which is detected by the first temperature sensor, from starting of the internal combustion engine exceeds a predetermined value.
  • ⁇ ECT rise quantity of a coolant water temperature
  • a first value indicating the predetermined value for the case where the electric pump operates during stopping of the internal combustion engine is larger than a second value indicating the predetermined value for the case where the electric pump does not operate during stopping of the internal combustion engine.
  • the failure diagnosis of the thermostat valve is performed based on the coolant water temperature. According to the cooling device for an internal combustion engine, starting of the failure diagnosis is adjusted based on the coolant water temperature. Therefore, a start timing of the failure diagnosis can be adjusted with a high accuracy.
  • the control device integrates an intake air volume to the internal combustion engine from starting of the internal combustion engine, and starts the failure diagnosis when the integrated value of the intake air volume exceeds a predetermined value.
  • a first value indicating the predetermined value for the case where the electric pump operates during stopping of the internal combustion engine is larger than a second value indicating the predetermined value for the case where the electric pump does not operate during stopping of the internal combustion engine.
  • the integrated amount of the intake air volume to the internal combustion engine may represent a tendency of a rise in the temperature of the internal combustion engine and of the coolant water. Therefore, in this cooling device for an internal combustion engine, starting of the failure diagnosis is adjusted based on the integrated amount of the intake air volume. Thus, this cooling device for an internal combustion engine can also suppress erroneous determination in the failure diagnosis for the thermostat valve.
  • the control device starts the failure diagnosis when an elapsed time from starting of the internal combustion engine exceeds a predetermined value.
  • a first value indicating the predetermined value for the case where the electric pump operates during stopping of the internal combustion engine is larger than a second value indicating the predetermined value for the case where the electric pump does not operate during stopping of the internal combustion engine.
  • starting of the failure diagnosis is adjusted based on the elapsed time from starting of the internal combustion engine. Therefore, a process for capturing a detection signal of a sensor and a calculation process are not required.
  • the process of the control device can be simplified. Moreover, starting of the failure diagnosis can be adjusted without being affected by an abnormality of a sensor and a measurement accuracy
  • the control device calculates an estimation value of the coolant water temperature in the radiator circulation passage based on a leakage flow rate through the radiator circulation passage in the closed state of the thermostat valve and on an output of the first temperature sensor, and diagnoses that the thermostat valve is failed in a case where an output value of the second temperature sensor is larger than the calculated estimation value.
  • the failure diagnosis of the thermostat valve is performed taking into consideration the leakage flow rate through the radiator circulation passage in the closed state of the thermostat valve. Therefore, the failure diagnosis can be performed with a high accuracy.
  • FIG. 1 represents a schematic configuration of a vehicle including a cooling device for an internal combustion engine according to an embodiment of the present invention.
  • FIG. 2 represents one example of a change in an engine coolant water temperature before and after starting the engine.
  • FIG. 3 is a flowchart for describing procedures of the thermostat valve failure diagnosis process executed by the ECU shown in FIG. 1 .
  • FIG. 4 is a flowchart representing process procedures for determining the diagnosis precondition shown in FIG. 3 .
  • FIG. 5 is a flowchart representing process procedures for determining a diagnosis precondition in Modified Example 1.
  • FIG. 6 is a flowchart representing process procedures for determining a diagnosis precondition in Modified Example 2.
  • FIG. 1 represents a schematic configuration of a vehicle including a cooling device for an internal combustion engine according to the embodiment of the present invention.
  • a vehicle 100 includes an engine 20 , an engine cooling device 10 for cooling engine 20 , and a thermal component 300 .
  • Engine cooling device 10 includes an electric water pump (hereinafter, referred to as “electric pump”) 30 , a radiator 40 , a radiator circulation passage 50 , a bypass passage 60 , and a thermostat valve 70 . Moreover, engine cooling device 10 further includes an engine-side coolant water temperature sensor 80 , a radiator-side coolant water temperature sensor 90 , and a control device (hereinafter, also referred to as “ECU (Electronic Control Unit)”) 200 .
  • ECU Electronic Control Unit
  • Engine 20 has a water jacket 24 for cooling engine 20 by means of coolant water.
  • Water jacket 24 is formed around cylinders of engine 20 and constitutes a coolant water passage 25 allowing coolant water to pass therethrough.
  • Coolant water passage 25 is provided between an inlet 27 and an outlet 26 , and allows coolant water from inlet 27 to be sent out from outlet 26 .
  • the coolant water flowing into coolant water passage 25 performs a heat exchange with engine 20 to cool engine 20 . Accordingly, engine 20 is maintained at a temperature which is suitable for combustion.
  • Electric pump 30 is a pump driven by an electric motor to circulate coolant water of engine 20 .
  • Electric pump 30 is mounted to an attachment-side surface portion 22 of an engine main body. Electric pump 30 allows coolant water to be sent out from inlet 27 into coolant water passage 25 .
  • Driving and stopping of electric pump 30 is controlled by a control signal received from ECU 200 . Further, a discharge amount of coolant water discharged from electric pump 30 is controlled by a control signal received from ECU 200 .
  • Outlet 26 constitutes a branch portion 120 .
  • Branch portion 120 is connected to radiator circulation passage 50 and bypass passage 60 .
  • Branch portion 120 separates coolant water from coolant water passage 25 into coolant water directed to radiator circulation passage 50 and coolant water directed to bypass passage 60 .
  • Radiator circulation passage 50 is a passage for circulating coolant water between engine 20 , electric pump 30 , and radiator 40 .
  • Radiator circulation passage 50 is constituted by pipes 50 a , 50 b and radiator 40 .
  • Pipe 50 a is provided between branch portion 120 and an inlet 42 of radiator 40 .
  • Pipe 50 b is provided between an outlet 44 of radiator 40 and thermostat valve 70 . Coolant water warmed up in engine 20 passes through radiator 40 and is cooled.
  • Radiator 40 performs a heat exchange between coolant water flowing in radiator 40 and outside air to thereby radiate heat of the coolant water.
  • Radiator 40 is provided with cooling fans 46 .
  • Cooling fan 46 accelerates a heat exchange through ventilation to improve a heat-radiation efficiency of the coolant water in radiator 40 .
  • Coolant water cooled in radiator 40 is sent out from outlet 44 .
  • Bypass passage 60 is a passage for circulating coolant water without passing through radiator 40 .
  • Bypass passage 60 is constituted by pipes 60 a , 60 b and thermal component 300 .
  • Pipe 60 a is provided between branch portion 120 and thermal component 300 .
  • Pipe 60 b is provided between thermal component 300 and thermostat valve 70 .
  • Thermal component 300 includes an EGR (Exhaust Gas Recirculation) cooler 28 , a pipe 29 , an exhaust heat recovery unit 32 , a heater core 36 , a throttle body 35 , and an EGR valve 34 .
  • EGR exhaust Gas Recirculation
  • EGR cooler 28 cools EGR gas by means of coolant water. Throttle body 35 is warmed up by coolant water to prevent occurrence of adhesion and the like. EGR valve 34 is cooled by the coolant water. Exhaust heat recovery unit 32 warms up the coolant water by heat of exhaust gas to thereby improve an engine mobility during a low temperature.
  • Heater core 36 is used as a heater of an air-conditioning device, and performs a heat exchange between coolant water and blast air of the air-conditioning device to heat the blast air. It should be note that the air-conditioning device may operate even during stopping of engine 20 . When a heating request is given by the air-conditioning device during stopping of engine 20 , electric pump 30 operates to circulate coolant water through bypass passage 60 , so that a heat exchange is performed by heater core 36 between the coolant water and the blast air of the air-conditioning device. This lowers the temperature of the coolant water flowing through bypass passage 60 .
  • Thermostat valve 70 is arranged at a merging portion 110 which merges coolant water having passed through radiator circulation passage 50 and coolant water having passed through bypass passage 60 .
  • Merging portion 110 is connected to radiator 40 through pipe 50 b and connected also to pipe 60 b .
  • the coolant water from merging portion 110 returns to a suction port of electric pump 30 .
  • Thermostat valve 70 is configured to be switched to either a closed state or an opened state in accordance with a temperature of coolant water flowing in thermostat valve 70 (in the vicinity of the valve body).
  • thermostat valve 70 attains a closed state.
  • coolant water on the side of bypass passage 60 passes through thermostat valve 70 and is outputted to water jacket 24 , but coolant water on the side of radiator circulation passage 50 is intercepted by thermostat valve 70 and not outputted to water jacket 24 . Accordingly, coolant water having taken heat from engine 20 flows back to engine 20 (water jacket 24 ) without being cooled by radiator 40 , so that engine 20 is warmed up.
  • thermostat valve 70 is attains an opened state.
  • coolant water from radiator circulation passage 50 and coolant water from bypass passage 60 pass through thermostat valve 70 and are outputted to water jacket 24 .
  • an opening degree of thermostat valve 70 is adjusted in accordance with a temperature of coolant water. Accordingly, a mixture ratio between the coolant water from radiator circulation passage 50 and the coolant water from bypass passage 60 is adjusted, so that the temperature of the coolant water passing through water jacket 24 is maintained at an appropriate temperature.
  • Engine-side coolant water temperature sensor 80 is provided at branch portion 120 .
  • Engine-side coolant water temperature sensor 80 detects a temperature of coolant water sent out from outlet 26 (hereinafter, referred to as “engine outlet water temperature ECT” or simply as “ECT”) and outputs a detection result (ECT detection value) to ECU 200 .
  • engine outlet water temperature ECT engine outlet water temperature ECT
  • ECT detection value detection result
  • engine-side coolant water temperature sensor 80 is all necessary to be provided on a passage through which coolant water always circulates, and it may be provided for example on coolant water passage 25 .
  • Radiator-side coolant water temperature sensor 90 is provided on pipe 50 a .
  • Radiator-side coolant water temperature sensor 90 detects a temperature of coolant water flowing into pipe 50 a of radiator circulation passage 50 (hereinafter, referred to as “radiator inlet water temperature RCT” or simply as “RCT”) and outputs a detection result (RCT detection value) to ECU 200 .
  • RCT radiator inlet water temperature
  • RCT detection value a detection result
  • thermostat valve 70 when thermostat valve 70 is failed, abnormalities may occur including a close failure in which the valve body does not open even if a coolant water temperature in the vicinity of the valve body rises beyond the valve-opening temperature, and an open failure in which the valve body does not close even if a coolant water temperature in the vicinity of the valve body is lowered to be less than the valve-opening temperature.
  • coolant water at an appropriate water temperature cannot be supplied to coolant water passage 25 of engine 20 , so that an operation efficiency of engine 20 is lowered. Therefore, it is preferable to continuously perform a failure diagnosis on whether or not thermostat valve 70 functions normally during operation of engine 20 to thereby find a failure in an early stage.
  • ECU 200 performs a failure diagnosis for thermostat valve 70 based on an ECT detection value received from engine-side coolant water temperature sensor 80 and an RCT detection value received from radiator-side coolant water temperature sensor 90 .
  • This ECU 200 is configured by a CPU (Central Processing Unit), a storage device, an input/output buffer, and the like (none of these are illustrated).
  • ECU 200 implements a failure diagnosis with a high diagnosis accuracy as will be described in the following.
  • thermostat valve 70 in a water temperature region where thermostat valve 70 essentially does not open (in a water temperature region lower than the valve-opening temperature) thermostat valve 70 is in the closed state. Therefore, theoretically, the coolant water flows into bypass passage 60 , and the coolant water does not flow into radiator circulation passage 50 . Therefore, a difference equal to or greater than a predetermined value occurs between the ECT detection value and the RCT detection value.
  • thermostat valve 70 in the water temperature region where thermostat valve 70 essentially does not open, when the difference between the ECT detection value and the RCT detection value is less than the predetermined value, it is determined that thermostat valve 70 is opened, in other words, an open failure occurs in thermostat valve 70 .
  • thermostat valve 70 even when thermostat valve 70 is normally closed, a rise in the water pressure in radiator circulation passage 50 by driving of electric pump 30 causes the coolant water in radiator circulation passage 50 to leak out from thermostat valve 70 to coolant water passage 25 .
  • coolant water of the amount corresponding to the leakage flow rate of thermostat valve 70 flows from coolant water passage 25 into radiator circulation passage 50 and is mixed with the coolant water present in radiator circulation passage 50 , so that radiator inlet water temperature RCT comes close to engine outlet water temperature ECT. Since it causes the temperature difference between the ECT detection value and the RCT detection value to be small, it may lower an accuracy of the failure diagnosis.
  • ECU 200 performs a failure diagnosis for thermostat valve 70 taking into consideration that the coolant water leaks out from thermostat valve 70 even when thermostat valve 70 is in a normal state. Specifically, ECU 200 performs a process of calculating an estimation value of radiator inlet water temperature RCT based on the ECT detection value and the leakage flow rate of thermostat valve 70 , and diagnosing whether or not thermostat valve 70 is failed based on a result of comparing the calculated RCT estimation value and the RCT detection value (hereinafter, referred to as “thermostat valve failure diagnosis process”). This thermostat valve failure diagnosis process will be described later in detail with reference to a flowchart.
  • the heat of the coolant water heated by the exhaust heat of engine 20 can be utilized for heating and the like by the air-conditioning device.
  • the heat is used for heating by the air-conditioning device with use of heater core 36 provided on bypass passage 60 .
  • the heat of the heated coolant water can be used even during stopping of engine 20 , and the coolant water may be circulated by operating electric pump 30 in accordance with a heating request or the like during stopping of engine 20 .
  • thermostat valve 70 is closed, and the coolant water does not flow into radiator circulation passage 50 but circulate through coolant water passage 25 of engine 20 and bypass passage 60 .
  • radiator inlet water temperature RCT the relationship between engine outlet water temperature ECT and radiator inlet water temperature RCT is inversed, so that erroneous determination may be made in the failure diagnosis.
  • FIG. 2 represents one example of a change in the engine coolant water temperature before and after starting of engine 20 .
  • FIG. 2 it is assumed that, before time t1, engine 20 is stopped, and use of a heater and the like during stopping of the engine causes a situation of ECT detection value ⁇ RCT detection value. It should be noted that the failure diagnosis for thermostat valve 70 is not performed during stopping of engine 20 .
  • engine 20 is started at time t1.
  • the engine coolant water is heated by the exhaust heat of engine 20 , and the ECT detection value indicating the temperature of the coolant water at the engine outlet starts to rise.
  • the temperature of the coolant water is lower than the valve-opening temperature of thermostat valve 70 , and thermostat valve 70 is closed, so that no rise in the RCT detection value can be seen.
  • the ECT detection value ⁇ RCT detection value continues, and it attains the ECT detection value >RCT detection value on or after time t2.
  • ECU 200 delays starting of the failure diagnosis process for thermostat valve 70 performed after starting of engine 20 as compared to the case where electric pump 30 does not operate during stopping of engine 20 . Accordingly, the failure diagnosis is avoided in the state where the relationship between the ECT detection value and the RCT detection value is inversed, so that the erroneous determination in the failure diagnosis is suppressed.
  • FIG. 3 is a flowchart for describing procedures of the thermostat valve failure diagnosis process executed by ECU 200 shown in FIG. 1 .
  • the process shown in this flowchart is executed at the time of starting engine 20 , for example, at the time of starting engine after idling stop.
  • the process is executed further at the time of starting an engine when switched from EV traveling with use of a drive force of a motor after stopping engine 20 to HV traveling with operation of engine 20 .
  • This flowchart is achieved by executing a program stored in ECU 200 at predetermined cycles, and the process of some steps can be achieved by constructing a dedicated hardware (electronic circuit).
  • ECU 200 calculates an estimation value of radiator inlet water temperature RCT (RCT estimation value) based on the ECT detection value received from engine-side coolant water temperature sensor 80 , and a leakage flow rate into radiator circulation passage 50 when thermostat valve 70 is in the closed state (Step S 10 ). Specifically, ECU 200 can calculate the RCT estimation value with use of the following expression as one example.
  • RCT estimation value (ECT detection value ⁇ leakage flow rate+RCT estimation value (previous value) ⁇ (pipe volume ⁇ leakage flow rate))/pipe volume (1)
  • the RCT estimation value is calculated based on the assumption that the coolant water with the ECT detection value and the coolant water with the RCT estimation value (previous value) are evenly mixed in accordance with a ratio of the leakage flow rate with respect to the pipe volume.
  • the leakage flow rate may be a fixed value determined in advance based on an experimental result or the like, or it may be a variable value set to have a larger value as the flow rate of electric pump 30 for example is larger.
  • the pipe volume is a volume of the pipe through which the coolant water flows from engine-side coolant water temperature sensor 80 to radiator-side coolant water temperature sensor 90 . It should be noted that the calculation accuracy can be improved by dividing the pipe into any number of regions and applying the expression of (1) described above to each divided region.
  • ECU 200 executes the process of determining whether or not a precondition for executing an open failure diagnosis process for thermostat valve 70 (hereinafter, simply referred to as “diagnosis precondition”) is met (Step S 20 ).
  • diagnosis precondition a precondition for executing an open failure diagnosis process for thermostat valve 70
  • Step S 20 The contents of this process will be described in detail in FIG. 4 which will be described later.
  • ECU 200 determines whether or not the thermostat open failure diagnosis process will be performed based on the process result of Step S 20 (Step S 30 ).
  • ECU 200 terminates the process without executing the thermostat open failure diagnosis process (processes of Steps S 40 to S 60 ). In other words, ECU 200 prohibits the thermostat open failure diagnosis process in the case where the diagnosis precondition is not met.
  • Step S 30 when it is determined in Step S 30 that the diagnosis precondition is met (YES in Step S 30 ), ECU 200 executes the thermostat open failure diagnosis process (the processes of Steps S 40 to S 60 ).
  • ECU 200 determines whether or not the RCT detection value received from radiator-side coolant water temperature sensor 90 is higher than the RCT estimation value calculated in Step S 10 (Step S 40 ). Then, when the RCT detection value is higher than the RCT estimation value (YES in Step S 40 ), ECU 200 determines that thermostat valve 70 is in the open failure state (Step S 50 ). This is because when thermostat valve 70 is in the open failure state, the heated coolant water of the amount larger than the expected leakage flow rate flows into radiator circulation passage 50 , and a situation in which the RCT detection value is higher than the RCT estimated value occurs. On the other hand, when the RCT detection value is equal to or lower than the RCT estimation value (NO in Step S 40 ), ECU 200 determines that thermostat valve 70 is normal (Step S 60 ).
  • FIG. 4 is a flowchart representing the process procedures for the diagnosis precondition determination executed in Step S 20 of FIG. 3 .
  • ECU 200 determines whether or not the monitoring precondition is met.
  • the monitoring precondition is a condition set as a precondition for monitoring a water temperature rise quantity ⁇ ECT indicating a rise in the coolant water temperature from starting of the engine in Steps S 130 and S 160 which will be described later.
  • ECU 200 determines that the monitoring precondition is met when all of the following conditions (a) to (f) are met.
  • the ECT detection value is less than the valve-opening temperature (for example, 70° C.) of thermostat valve 70 .
  • the ECT detection value at the time of starting the engine is included in the range of ⁇ 10° C. to +56° C.
  • the time change quantity of the ECT detection value is equal to or greater than a predetermined value (for example, 0.1° C./second).
  • Condition (a) provides the premise that the thermostat failure diagnosis is performed once between starting of engine 20 and stopping next.
  • Condition (b) is a condition for assuring that thermostat valve 70 is essentially (if it is normal) closed.
  • Conditions (c) and (d) are conditions for assuring that the ECT detection value increases in a manner capable of performing the thermostat failure diagnosis after starting the engine.
  • Condition (e) is a condition for assuring a rise in the engine water temperature after starting the engine.
  • Condition (f) is a condition for assuring a reliability of the ECT detection value or the RCT detection value. It should be noted that, as the monitoring precondition, conditions (a) to (f) described above may be selected as needed.
  • Step S 110 When it is determined in Step S 110 that the monitoring precondition is not met (NO in Step S 110 ), ECU 200 shifts the process to Step S 180 and determines that the diagnosis precondition is not met (Step S 180 ).
  • Step S 110 When it is determined in Step S 110 that the monitoring precondition is met (YES in Step S 110 ), ECU 200 determines whether or not electric pump 30 operates during previous stopping of the engine (from previous stopping of the engine to the current starting of the engine) (Step S 120 ).
  • ECU 200 determines whether or not the water temperature rise quantity ⁇ ECT indicating a rise in the quantity of the ECT detection value after starting of engine 20 is larger than a predetermined value A (>predetermined value B) (Step S 130 ).
  • This predetermined value A is a determination value of the diagnosis precondition for the case where electric pump 30 operates during stopping of the engine, and it is larger than a determination value B (default value) of the diagnosis precondition for the case where electric pump 30 does not operate during stopping of the engine.
  • predetermined value B is 1° C.
  • predetermined value A is 3° C. Accordingly, starting of the failure diagnosis for the case where electric pump 30 operates during stopping of the engine can be delayed as compared to the case where electric pump 30 does not operate during stopping of the engine.
  • Step S 130 determines that water temperature rise quantity ⁇ ECT is larger than predetermined value A (YES in Step S 130 ).
  • ECU 200 determines that the diagnosis precondition is met (Step S 140 ).
  • Step S 130 determines that water temperature rise quantity ⁇ ECT is less than or equal to predetermined value A (NO in Step S 130 )
  • Step S 150 it is determined that the diagnosis precondition is not met.
  • Step S 120 determines whether or not water temperature rise quantity ⁇ ECT is larger than predetermined value B (Step S 160 ).
  • Step S 160 determines that water temperature rise quantity ⁇ ECT is larger than predetermined value B (YES in Step 160 )
  • ECU 200 determines that the diagnosis precondition is met (Step S 170 ).
  • Step S 180 determines that the diagnosis precondition is not met (Step S 180 ).
  • this engine cooling device 10 in the case where electric pump 30 operates in accordance with a heating request or the like of the air-conditioning device during stopping of engine 20 , starting of the failure diagnosis performed after starting of engine 20 is delayed as compared to the case where electric pump 30 does not operate during stopping of engine 20 , so that starting of the failure diagnosis of thermostat valve 70 in the state where the relationship between engine outlet water temperature ECT and radiator inlet water temperature RCT is inversed can be avoided.
  • erroneous determination can be suppressed in the failure diagnosis of thermostat valve 70 .
  • thermostat valve 70 is performed based on the temperature of the coolant water
  • starting of the failure diagnosis is adjusted based on the coolant water temperature, so that the start timing of the failure diagnosis can be adjusted with a high accuracy.
  • thermostat valve 70 is performed taking into consideration the leakage flow rate through radiator circulation passage 50 in the closed state of thermostat valve 70 , so that the failure diagnosis can be performed with a high accuracy.
  • starting of the thermostat valve failure diagnosis process after starting of the engine is delayed based on the rise quantity ( ⁇ ECT) of the engine coolant water temperature (ECT detection value) after starting of engine 20 .
  • ⁇ ECT rise quantity of the engine coolant water temperature
  • ECT detection value water temperature rise quantity
  • an integrated amount of the intake air volume into engine 20 from starting of engine 20 may be used. This is because the integrated intake air volume from starting of engine 20 may represent a tendency of the rise in temperatures of engine 20 and the coolant water.
  • the overall configuration of the vehicle in this Modified Example 1 is the same as vehicle 100 shown in FIG. 1 .
  • the procedures of the overall process of the thermostat valve failure diagnosis executed by ECU 200 of this Modified Example 1 is the same as the process procedures shown in FIG. 3 .
  • FIG. 5 is a flowchart representing process procedures of the diagnosis precondition determination (the process executed in Step S 20 of FIG. 3 ) in this Modified Example 1.
  • this flowchart includes, in the flowchart shown in FIG. 4 , Steps S 132 and S 136 in place of Steps S 130 and S 160 .
  • Step S 120 determines whether or not an integrated intake air volume indicating an integrated amount of the intake air volume into engine 20 from starting of engine 20 is greater than a predetermined value C (>predetermined value D) (Step S 132 ).
  • predetermined value C is a determination value of the diagnosis precondition for the case where electric pump 30 operates during stopping of the engine, and it is larger than determination value D (default value) for the case where electric pump 30 does not operate during stopping of the engine.
  • predetermined value C is 50 g
  • predetermined value D is 20 g.
  • the intake air volume into engine 20 can be detected with use of an air flow meter. With predetermined value C >predetermined value D, starting of the failure diagnosis for the case where electric pump 30 operates during stopping of the engine can be delayed as compared to the case where electric pump 30 does not operate during stopping of the engine.
  • Step S 132 when it is determined in Step S 132 that the integrated intake air volume is larger than predetermined value C (YES in Step S 132 ), the process is shifted to Step S 140 , and it is determined that the diagnosis precondition is met.
  • Step S 150 When it is determined that the integrated intake air volume is equal to or less than predetermined value C in Step S 132 (NO in Step S 132 ), the process is shifted to Step S 150 , and it is determined that the diagnosis precondition is not met.
  • Step S 120 determines whether or not the integrated intake air volume is larger than predetermined value D (Step S 162 ). Then, when it is determined that the integrated intake air volume is larger than predetermined value D (YES in Step S 162 ), the process is shifted to Step S 170 , and it is determined that the diagnosis precondition is met. When it is determined in Step S 162 that the integrated intake air volume is less than or equal to predetermined value D (NO in Step S 162 ), the process is shifted to Step S 180 , and it is determined that the diagnosis precondition is not met.
  • the overall configuration of the vehicle in this Modified Example 2 is the same as that of vehicle 100 shown in FIG. 1 . Moreover, the procedures of the overall process of the thermostat valve failure diagnosis executed by ECU 200 in this Modified Example 2 are the same as the process procedures shown in FIG. 3 .
  • FIG. 6 is a flowchart representing the process procedures for determining the diagnosis precondition (the process executed in Step S 20 of FIG. 3 ) in this Modified Example 2.
  • this flowchart includes, in the flowchart shown in FIG. 4 , Steps S 134 and S 164 in place of Steps S 130 and S 160 .
  • Step S 120 when it is determined in Step S 120 that electric pump 30 operates during previous stopping of the engine (YES in Step S 120 ), ECU 200 determines whether or not an elapsed time from starting of engine 20 exceeds a predetermined value T1 (>predetermined value T2) (Step S 134 ).
  • predetermined value T1 is a determination value of the diagnosis precondition for the case where electric pump 30 operates during stopping of the engine, and it is larger than determination value T2 (default value) of the diagnosis precondition for the case where electric pump 30 does not operate during stopping of the engine.
  • predetermined value T1 is 5 seconds
  • predetermined value T2 is 2 seconds.
  • the elapsed time from starting of engine 20 can be measured by means of a timer or the like not illustrated in the drawings.
  • predetermined value T1>predetermined value T2 starting of the failure diagnosis for the case where electric pump 30 operates during stopping of the engine can be delayed as compared to the case where electric pump 30 does not operate during stopping of the engine.
  • Step S 134 when it is determined in Step S 134 that the elapsed time exceeds predetermined value T1 (YES in Step S 134 ), the process is shifted to Step S 140 , and it is determined that the diagnosis precondition is met.
  • Step S 134 When it is determined in Step S 134 that the elapsed time is less than or equal to predetermined value T1 (NO in Step S 134 ), the process is shifted to Step S 150 , and it is determined that the diagnosis precondition is not met.
  • Step S 120 when it is determined in Step S 120 that electric pump 30 does not operate during previous stopping of the engine (NO in Step S 120 ), ECU 200 determines whether or not the elapsed time exceeds predetermined value T2 (Step S 164 ). Then, when it is determined that the elapsed time exceeds predetermined value T2 (YES in Step S 164 ), the process is shifted to Step S 170 , and it is determined that the diagnosis precondition is met. When it is determined in Step S 164 that the elapsed time is less than or equal to predetermined value T2 (NO in Step S 164 ), the process is shifted to Step S 180 , and it is determined that the diagnosis precondition is not met.
  • starting of the failure diagnosis is adjusted based on the elapsed time from starting of engine 20 . Therefore, the process of capturing a detection signal of a sensor and the calculation process are not required. Thus, according to this Modified Example 2, the process of ECU 200 can be simplified. Moreover, starting of the failure diagnosis can be adjusted without being affected by an abnormality of the sensor and the measurement accuracy.
  • thermostat valve 70 is performed taking into consideration the leakage flow rate through radiator circulation passage 50 in the closed state of thermostat valve 70 in the embodiment described above and Modified Examples 1 and 2 thereof, the method of the failure diagnosis is not limited to such methods.
  • the present invention is applicable for the case where the failure diagnosis is performed based on the comparison between ECT detection value and the RCT detection value in more simple manner.
  • this invention is applicable also to a hybrid vehicle provided with a traveling motor in addition to engine 20 and a vehicle not provided with the traveling motor.
  • this invention is applicable to starting of the engine after idling stop or after IG-on operation by a user.
  • this invention is further applicable to starting of engine when switching from the EV traveling to the HV traveling.
  • engine 20 corresponds to one example of the “internal combustion engine” of this invention
  • heater core 36 corresponds to one example of the “heat exchanger” of this invention
  • engine-side coolant water temperature sensor 80 corresponds to one example of the “first temperature sensor” of this invention
  • radiator-side coolant water temperature sensor 90 corresponds to one example of the “second temperature sensor” of this invention.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
US14/534,477 2013-12-03 2014-11-06 Cooling device for internal combustion engine Abandoned US20150152775A1 (en)

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JP2013250213A JP5839021B2 (ja) 2013-12-03 2013-12-03 内燃機関の冷却装置

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US20150107345A1 (en) * 2013-10-17 2015-04-23 Toyota Jidosha Kabushiki Kaisha Cooling Device for Internal Combustion Engine and Failure Diagnosis Method for Cooling Device for Internal Combustion Engine
CN105298613A (zh) * 2015-08-07 2016-02-03 宁波吉利罗佑发动机零部件有限公司 发动机双回路冷却系统及冷却方法
JP2017125419A (ja) * 2016-01-12 2017-07-20 株式会社デンソー 水温制御装置及び温度推定方法
US20180073418A1 (en) * 2016-09-15 2018-03-15 Ford Global Technologies, Llc Method and system for monitoring cooling system
US10471803B2 (en) * 2016-01-27 2019-11-12 Ford Global Technologies, Llc Systems and methods for thermal battery control
US20210408871A1 (en) * 2018-11-12 2021-12-30 KSB SE & Co. KGaA Electric Motor
US11318814B2 (en) * 2018-03-22 2022-05-03 Denso Corporation Cooling apparatus

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CN105298614B (zh) * 2015-08-07 2017-10-31 宝鸡吉利发动机零部件有限公司 集成水泵及具有集成水泵的发动机冷却系统和冷却方法
JP7192621B2 (ja) * 2019-03-29 2022-12-20 新東工業株式会社 検査装置

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JP3777776B2 (ja) * 1998-02-04 2006-05-24 マツダ株式会社 エンジンの冷却装置の異常診断装置
DE19948249A1 (de) * 1999-10-07 2001-04-26 Bayerische Motoren Werke Ag Kühlsystem für eine Brennkraftmaschine in Kraftfahrzeugen
JP4174954B2 (ja) * 2000-04-06 2008-11-05 株式会社デンソー 内燃機関のサーモスタット故障検出装置
JP4260551B2 (ja) * 2003-05-30 2009-04-30 本田技研工業株式会社 内燃機関のサーモスタットの故障を検出する装置
JP4830960B2 (ja) * 2007-04-19 2011-12-07 トヨタ自動車株式会社 内燃機関の冷却装置

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150107345A1 (en) * 2013-10-17 2015-04-23 Toyota Jidosha Kabushiki Kaisha Cooling Device for Internal Combustion Engine and Failure Diagnosis Method for Cooling Device for Internal Combustion Engine
US9695736B2 (en) * 2013-10-17 2017-07-04 Toyota Jidosha Kabushiki Kaisha Cooling device for internal combustion engine and failure diagnosis method for cooling device for internal combustion engine
CN105298613A (zh) * 2015-08-07 2016-02-03 宁波吉利罗佑发动机零部件有限公司 发动机双回路冷却系统及冷却方法
JP2017125419A (ja) * 2016-01-12 2017-07-20 株式会社デンソー 水温制御装置及び温度推定方法
US10471803B2 (en) * 2016-01-27 2019-11-12 Ford Global Technologies, Llc Systems and methods for thermal battery control
US20180073418A1 (en) * 2016-09-15 2018-03-15 Ford Global Technologies, Llc Method and system for monitoring cooling system
US10494984B2 (en) * 2016-09-15 2019-12-03 Ford Global Technologies, Llc Method and system for monitoring cooling system
US11318814B2 (en) * 2018-03-22 2022-05-03 Denso Corporation Cooling apparatus
US20210408871A1 (en) * 2018-11-12 2021-12-30 KSB SE & Co. KGaA Electric Motor

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