Water pump diagnostic device

Abstract

To make it possible to diagnose whether or not a water pump has a failure without being based on the rotation speed of the water pump.SOLUTION: A water pump diagnosis device diagnoses a water pump that circulates a coolant for cooling a cooling target. The water pump diagnosis device comprises a temperature sensor and a diagnosis unit. The temperature sensor measures the temperature of a power semiconductor that is a part of the cooling target. The diagnosis unit determines whether the water pump has a failure on the basis of a comparison between a temperature rise rate of the power semiconductor based on the temperature measured by the temperature sensor and a preset reference temperature rise rate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a water pump diagnostic device for detecting a failure in a water pump. [Background technology]

[0002] 2. Description of the Related Art Some vehicles are equipped with a water pump that circulates a refrigerant for cooling an object to be cooled, such as a vehicle control unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-115680 Summary of the Invention [Problem to be solved by the invention]

[0004] If the water pump fails and the flow rate of the refrigerant decreases, the temperature of the object to be cooled will rise, which can cause various problems. For this reason, it is desirable to be able to quickly diagnose whether the water pump is malfunctioning.

[0005] One technique for detecting a water pump failure is to diagnose whether the water pump is malfunctioning based on the rotational speed of the water pump. However, this method cannot diagnose whether the water pump is malfunctioning if the water pump does not have a rotational speed sensor.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to diagnose whether or not a water pump has failed without relying on the rotation speed of the water pump. [Means for solving the problem]

[0007] The inventors discovered that by focusing on the temperature rise of the power semiconductor as part of the object to be cooled, it is possible to detect a failure of the water pump without relying on the rotation speed of the water pump, and arrived at the present invention. The present invention is a water pump diagnostic device as described below in (1) to (5).

[0008] (1) A water pump diagnostic device for diagnosing a water pump that circulates a refrigerant that cools an object to be cooled, a temperature sensor for measuring the temperature of a power semiconductor that is a part of the cooling target; a diagnostic unit that determines whether the water pump is faulty based on a comparison between a temperature rise rate of the power semiconductor based on the temperature measured by the temperature sensor and a preset reference temperature rise rate; A water pump diagnostic device comprising:

[0009] According to this configuration, the coolant flow rate can be estimated by comparing the temperature rise rate of the power semiconductor with the reference temperature rise rate. That is, the coolant flow rate can be estimated to be smaller the greater the temperature rise rate of the power semiconductor compared to the reference temperature rise rate. This makes it possible to diagnose whether the water pump is malfunctioning without relying on the rotation speed of the water pump.

[0010] (2) The object to be cooled, the water pump, and the water pump diagnostic device are mounted on a vehicle, the object to be cooled includes a power module for driving the vehicle, The power semiconductor is part of the power module. The water pump diagnostic device according to (1) above.

[0011] According to this configuration, the above-mentioned effect can be obtained in a vehicle, that is, the effect that it is possible to diagnose whether or not a water pump has failed without relying on the rotation speed of the water pump.

[0012] (3) The water pump diagnostic device according to (1) or (2), further comprising a warning unit that warns that the water pump is faulty, on condition that the diagnostic unit determines that the water pump is faulty.

[0013] According to this configuration, when the water pump fails, the driver can quickly recognize that fact.

[0014] (4) The diagnostic unit determining that the water pump is faulty on the condition that a difference in temperature rise rate, which is a value obtained by subtracting the reference temperature rise rate from the temperature rise rate of the power semiconductor based on the temperature measured by the temperature sensor, is greater than a predetermined fault determination value; determining that the water pump is stopped on condition that the increase speed difference is greater than a stop determination value that is greater than the malfunction determination value; The water pump diagnostic device according to any one of (1) to (3) above.

[0015] According to this configuration, the condition of the water pump can be diagnosed in detail.

[0016] (5) The water pump diagnostic device according to (4) above, further comprising a warning unit that warns that the water pump is faulty if the diagnostic unit determines that the water pump is faulty, and that warns that the water pump is stopped if the diagnostic unit determines that the water pump is stopped.

[0017] According to this configuration, the driver can recognize the state of the water pump in detail. [Effects of the Invention]

[0018] As described above, the configuration (1) allows the diagnosis of whether the water pump is malfunctioning without relying on the rotational speed of the water pump. Furthermore, the configurations (2) to (4) that refer to the configuration (1) provide additional effects. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a configuration diagram showing a water pump diagnostic device and its surroundings according to a first embodiment. [Figure 2] FIG. 2 is a plan view showing an example of a power semiconductor and its periphery. [Figure 3] FIG. 2 is a front view showing an example of a power semiconductor and its periphery. [Figure 4] 10 is a graph showing the relationship between the operating time and the temperature of the power semiconductor for each flow rate of the refrigerant. [Figure 5] 4 is a flowchart showing a flow of diagnosis by the water pump diagnostic device. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments and can be appropriately modified and implemented within the scope of the present invention.

[0021] [First embodiment] 1, a water pump diagnostic device 60 of this embodiment is mounted on a vehicle 100. The vehicle 100 is equipped with a VCU 70, a water pump 80, and a radiator 90. VCU is an abbreviation for "Vehicle Control Unit."

[0022] The VCU 70 includes an ECU 20, a capacitor 30, an IPM 40, and a reactor 50. "ECU" stands for "Electronic Control Unit." "IPM" stands for "Intelligent Power Module." In other words, the "IPM" is a power module for running a vehicle.

[0023] The IPM 40 includes an input circuit that inputs power to the reactor 50 and an output circuit that outputs power from the reactor 50. Therefore, as shown in Fig. 2, the IPM 40 includes a plurality of power semiconductors such as semiconductor switches 44 and diodes 45. The capacitor 30 shown in Fig. 1 is, for example, a smoothing capacitor in the input circuit or a smoothing capacitor in the output circuit.

[0024] The ECU 20 shown in FIG. 1 controls the IPM 40 by controlling the semiconductor switches 44 shown in FIG.

[0025] Water pump 80 shown in FIG. 1 circulates refrigerant CL for cooling condenser 30, IPM 40, and reactor 50 within vehicle 100. Hereinafter, condenser 30, IPM 40, and reactor 50 will be referred to as "cooling targets 30, 40, 50." Water pump 80 cools cooling targets 30, 40, 50 by circulating refrigerant CL between cooling targets 30, 40, 50 and radiator 90. Specifically, as shown in FIG. 3, for example, refrigerant CL passes between cooling promotion fins 48 below cooling targets 30, 40, 50.

[0026] 1, water pump diagnostic device 60 includes a temperature sensor 61, a temperature rise rate identifying unit 62, a diagnostic unit 63, and a warning unit 65. Temperature sensor 61 is mounted inside IPM 40. Temperature rise rate identifying unit 62 and diagnostic unit 63 are each configured as part of ECU 20. Warning unit 65 is provided in vehicle 100, for example, in front of or around the driver's seat.

[0027] The temperature sensor 61 measures the temperature Ta of the semiconductor switch 44. The temperature rise rate identifying unit 62 identifies the temperature rise rate Va of the semiconductor switch 44 from the rise in the temperature Ta of the semiconductor switch 44 relative to the operating time t of the semiconductor switch 44.

[0028] The diagnosis unit 63 stores a preset reference temperature rise rate Vb. Specifically, the diagnosis unit 63 stores a map of the reference temperature rise rate Vb for each situation. As shown in FIG. 4, the reference temperature rise rate Vb is the rate of rise of the temperature Ta=Tb of the semiconductor switch 44 when the water pump 80 is normal, that is, when the flow rate of the refrigerant CL is high. The reference temperature rise rate Vb may be a value obtained in advance by experiment or simulation, for example.

[0029] 1 diagnoses the water pump 80 based on a comparison between the temperature rise rate Va of the semiconductor switch 44 identified by the temperature rise rate identification unit 62 and a reference temperature rise rate Vb. Hereinafter, the value (Va-Vb) obtained by subtracting the reference temperature rise rate Vb from the temperature rise rate Va of the semiconductor switch 44 will be referred to as the "rise rate difference ΔV." Furthermore, the two predetermined thresholds will be referred to as the "failure determination value th1" and the "stop determination value th2," in order from the smallest to the largest.

[0030] If the rising speed difference ΔV is less than the malfunction determination value th1, the diagnosis unit 63 determines that the water pump 80 is normal. On the other hand, if the rising speed difference ΔV is greater than the malfunction determination value th1, the diagnosis unit 63 determines that the water pump 80 is malfunctioning. Furthermore, if the rising speed difference ΔV is greater than the stop determination value th2, the diagnosis unit 63 determines that the water pump 80 is stopped.

[0031] If the diagnosis unit 63 determines that the water pump 80 is malfunctioning, the warning unit 65 warns the driver of the vehicle 100 that the water pump 80 is malfunctioning. Specifically, for example, the warning unit 65 warns that the flow rate of the refrigerant CL is decreasing. Furthermore, if the diagnosis unit 63 determines that the water pump 80 is stopped, the warning unit 65 warns the driver of the vehicle 100 that the water pump 80 is stopped. Note that these warnings may be visual, such as a warning screen display or a warning lamp, or auditory, such as a warning sound or warning announcement, or both.

[0032] Next, the flow of diagnosis by the water pump diagnostic device 60 described above will be described with reference to Figure 5. Note that in the following, "S" before the numbers stands for "step."

[0033] First, in S1, the temperature sensor 61 detects the temperature Ta of the semiconductor switch 44. Next, in S2, the temperature rise rate identifying unit 62 identifies the temperature rise rate Va of the semiconductor switch 44.

[0034] Next, in S3, the diagnosis unit 63 determines whether the rising speed difference ΔV exceeds the malfunction determination value th1. If the determination is negative, that is, if the rising speed difference ΔV is less than the malfunction determination value th1, the water pump 80 is determined to be normal, and the flow ends. On the other hand, if the diagnosis unit 63 determines positive in S3, that is, if the rising speed difference ΔV exceeds the malfunction determination value th1, the water pump 80 is determined to be malfunctioning, and the flow proceeds to S4.

[0035] In S4, the diagnosis unit 63 determines whether the increase speed difference ΔV exceeds the stop determination value th2. If the determination is negative, that is, if the increase speed difference ΔV is less than the stop determination value th2, it is determined that the water pump 80 is not stopped, and the process proceeds to S5. In S5, the warning unit 65 warns that the refrigerant flow rate is decreasing.

[0036] On the other hand, if the diagnosis unit 63 makes a positive determination in S5, that is, if the rising speed difference ΔV exceeds the stop determination value th2, it determines that the water pump 80 has stopped and proceeds to S6, where the warning unit 65 issues a warning that the water pump 80 has stopped.

[0037] The configuration and effects of this embodiment are summarized below.

[0038] 1 measures the temperature Ta of the semiconductor switch 44, which is part of the object to be cooled 30, 40, 50. The diagnosis unit 63 determines whether the water pump 80 has malfunctioned by comparing the rate of temperature rise Va of the semiconductor switch 44, which is based on the temperature Ta measured by the temperature sensor 61, with a preset reference rate of temperature rise Vb. That is, the flow rate of the refrigerant CL can be estimated to be smaller the greater the rate of temperature rise Va of the semiconductor switch 44 is compared to the reference rate of temperature rise Vb. Therefore, it is possible to diagnose whether the water pump 80 has malfunctioned without relying on the rotation speed of the water pump 80.

[0039] Cooling objects 30, 40, 50, water pump 80, and water pump diagnostic device 60 are mounted on vehicle 100. Cooling objects 30, 40, 50 include IPM 40 for running vehicle 100. Semiconductor switch 44 that measures temperature is part of IPM 40. As a result, the above-described effect can be obtained within vehicle 100, that is, the effect of being able to diagnose whether water pump 80 is malfunctioning or not, even without being based on the rotational speed of water pump 80.

[0040] On condition that diagnosis unit 63 determines that water pump 80 has failed, warning unit 65 warns the driver of vehicle 100 that water pump 80 has failed. Therefore, when water pump 80 has failed, the driver can quickly recognize that fact.

[0041] The diagnostic unit 63 determines that the water pump 80 is malfunctioning if the rising speed difference ΔV is greater than a malfunction determination value th1. The diagnostic unit 63 also determines that the water pump 80 is stopped if the rising speed difference ΔV is greater than a stop determination value th2. This allows the diagnostic unit 63 to diagnose the malfunction state of the water pump in detail.

[0042] If the diagnosis unit 63 determines that the water pump 80 is malfunctioning, the warning unit 65 warns the driver that the water pump 80 is malfunctioning. Also, if the diagnosis unit 63 determines that the water pump 80 is stopped, the warning unit 65 warns the driver that the water pump 80 is stopped. This allows the driver to recognize the malfunction state of the water pump 80 in detail.

[0043] [Other embodiments] The embodiment described above can be modified as follows, for example.

[0044] The diagnosis unit 63 may simply determine that the water pump 80 has failed when the rising speed difference ΔV is greater than the failure determination value th1, without determining whether the water pump 80 has stopped. The warning unit 65 may simply warn the driver that the water pump 80 has failed, on the condition that the diagnosis unit 63 has determined that the water pump 80 has failed.

[0045] If the diagnostic unit 63 determines that the water pump 80 has failed or stopped, a predetermined fail-safe action may be taken instead of or in addition to a warning from the warning unit 65.

[0046] Instead of measuring the temperature of the semiconductor switch 44 shown in FIG. 2, the temperature sensor 61 may measure the temperature of the diode 45. [Explanation of symbols]

[0047] 44 Semiconductor switches (power semiconductors) 45 Diode (power semiconductor) 60 Water pump diagnostic device 61 Temperature Sensor 63 Diagnostic Department 65 Warning section 80 Water Pump 100 vehicles th1 failure judgment value th2 Stop judgment value Va Temperature rise rate of semiconductor switch (temperature rise rate of power semiconductor) Vb Reference temperature rise rate ΔV temperature rise difference

Claims

1. A water pump diagnostic device for diagnosing a water pump that circulates a refrigerant that cools an object to be cooled, comprising: a temperature sensor for measuring the temperature of a power semiconductor that is a part of the cooling target; a temperature rise rate identification unit that identifies a temperature rise rate of the power semiconductor from a rise in temperature of the power semiconductor based on measurement by the temperature sensor with respect to an operating time of the power semiconductor; a diagnosis unit that determines whether the water pump is malfunctioning based on a temperature rise rate difference obtained by subtracting a preset reference temperature rise rate from the identified temperature rise rate, the reference temperature rise rate is a temperature rise rate of the power semiconductor when the water pump is normal, The diagnosing unit determines that the water pump is malfunctioning when the increase speed difference is greater than a predetermined malfunction determination value, and determines that the water pump is stopped when the increase speed difference is greater than a stop determination value that is greater than the malfunction determination value. Water pump diagnostic device.

2. the object to be cooled, the water pump, and the water pump diagnostic device are mounted on a vehicle, the object to be cooled includes a power module for driving the vehicle, The power semiconductor is part of the power module. The water pump diagnostic device according to claim 1 .

3. 3. The water pump diagnostic device according to claim 1, further comprising a warning unit that warns of a malfunction of the water pump when the diagnosing unit determines that the water pump is malfunctioning.

4. 3. The water pump diagnostic device according to claim 1, further comprising a warning unit that warns of a malfunction of the water pump when the diagnosing unit determines that the water pump is malfunctioning, and that warns of a stoppage of the water pump when the diagnosing unit determines that the water pump is stopped.

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