Cooling water reduction abnormality detection device for cooling water circuit

Abstract

To provide a cooling water reduction abnormality detection device for a cooling water circuit capable of detecting that reduction of cooling water occurs in a cooling water circuit into which cooling water is injected.SOLUTION: A cooling water reduction anomaly detection device for a cooling water circuit comprises: a flag setting unit that, when a rotation speed of an electric water pump fluctuates so as to repeatedly go between maximum and minimum points, compares the rotation speed of the electric water pump with a rotation speed obtained by dividing the sum of a maximum value stored in a maximum value memory unit and a minimum value stored in a minimum value memory unit, and sets a flag each time the rotation speed goes beyond the maximum value or falls below the minimum value; and an EWP rotation speed vibration determination unit that determines that the rotation speed of the electric water pump is vibrating when a ratio of the number of flags set within a time longer than a predetermined unit time to the number of flags set within a predetermined unit time falls within a predetermined range.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a coolant flow rate reduction abnormality detection device for a coolant circuit. [Background technology]

[0002] In a coolant circuit in which coolant circulates through a condenser tank, an electric water pump (hereinafter also referred to as an EWP as necessary), and the equipment to be cooled in that order, when the amount of coolant pumped into the coolant circuit decreases, the water level in the condenser tank drops, which reduces the condenser tank's air-water separation performance and increases the rate at which air is mixed into the coolant drawn into the electric water pump. It is known that an increase in the rate at which air is mixed into the coolant reduces the specific gravity of the coolant drawn into and discharged by the electric water pump, reducing the force (rotational resistance) required to rotate the electric water pump and causing the electric water pump's rotation speed to excessively increase. Patent Document 1 discloses a method for detecting a coolant leak by referring to the discrepancy between the expected and actual rotation speeds of an electric water pump. For example, the presence or absence of a coolant leak can be determined by subtracting the expected rotation speed from the actual rotation speed and determining whether the difference exceeds a predetermined value. The presence or absence of a coolant leak can also be determined by dividing the actual rotation speed by the expected rotation speed and determining whether the resulting ratio exceeds a predetermined reference value (a value greater than 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-90082 Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, electric water pumps that can change the rotation speed by external commands generally use pulse width modulation (PWM). The EWP is controlled by a frequency modulation (FFT), and the host ECU can command the EWP drive state as a drive rate (drive duty) of 0 to 100%, but electric water pumps vary from one another, and even when the same drive duty command is received, the rotation speed of electric water pumps will vary. Therefore, even if the rotation speed used to detect an excessive increase in rotation speed due to a coolant loss abnormality caused by a coolant leak due to damage to the coolant circuit, or coolant evaporation over time via the coolant circuit pressure valve (intake and exhaust valve), or insufficient water filling during maintenance, is set to be able to determine an excessive increase in rotation speed for an individual electric water pump, there is a risk that a normal state in which no coolant leak is occurring will be judged to be abnormal due to variation between electric water pumps and variation in pressure loss in the coolant circuit (variation in water flow resistance). Also, if the rotation speed used to detect an excessive increase is set with enough margin to account for the aforementioned variation, there is a risk that a decrease in coolant level due to a coolant leak, etc., will be overlooked.

[0005] In view of the above circumstances, at least one embodiment of the present invention aims to provide a coolant water reduction abnormality detection device for a coolant circuit that can detect a coolant water reduction abnormality occurring in a coolant circuit into which coolant is poured. [Means for solving the problem]

[0006] A widely known coolant circuit includes a condenser tank for storing coolant, an electric water pump installed below the condenser tank in the direction of gravity and connected to the condenser tank, an electric water pump discharge path connected to the electric water pump and extending above the electric water pump in the direction of gravity, and a cooled device connected to the electric water pump discharge path, in which the coolant circulates through the condenser tank, the electric water pump, the electric water pump discharge path, and the cooled device in that order. The inventors of the present application have discovered that when the amount of coolant supplied to the coolant circuit decreases, the water level in the condenser tank drops, and the rate of air mixed into the coolant continues to increase, the coolant no longer flows continuously through the electric water pump discharge path, and the effect of air-water separation of the coolant discharged from the electric water pump cannot be denied. The coolant immediately after being discharged from the electric water pump alternates between backflow and stagnation in the coolant circuit due to gravity and the electric water pump's normal discharge of coolant, causing the electric water pump's rotation speed to fluctuate. Therefore, the inventors of the present application came up with the idea of ​​detecting whether a coolant water level drop abnormality has occurred in the coolant circuit into which coolant water is injected by determining whether the rotation speed of the electric water pump is vibrating.

[0007] (1) At least one embodiment of the present invention provides a coolant circuit anomaly detection device for detecting a decrease in coolant level, the coolant circuit anomaly detection device comprising: a condenser tank for storing coolant; an electric water pump connected to the condenser tank and disposed below the condenser tank in the direction of gravity; an electric water pump discharge path connected to the electric water pump and extending above the electric water pump in the direction of gravity; and a cooled device connected to the electric water pump discharge path. When the coolant supplied to the coolant circuit, through which the coolant circulates in the order of the condenser tank, the electric water pump, the electric water pump discharge path, and the cooled device, becomes low, the rotation speed of the electric water pump vibrates, and the device detects that the vibration continues to occur, thereby determining whether an anomaly has occurred. The device includes an electric water pump rotation speed measurement unit for measuring the rotation speed of the electric water pump; a maximum value storage unit that updates and stores the rotation speed measured by the electric water pump rotation speed measurement unit as a maximum value if the rotation speed is increasing, and continues to store the immediately preceding maximum value if the rotation speed is decreasing; a minimum value storage unit that updates and stores the rotation speed measured by the electric water pump rotation speed measurement unit as a minimum value if the rotation speed is decreasing, and continues to store the immediately preceding minimum value if the rotation speed is increasing; a flag setting unit that, when the rotation speed of the electric water pump fluctuates so as to repeatedly have maximum and minimum points, compares the rotation speed obtained by dividing the sum of the maximum value stored in the maximum value storage unit and the minimum value stored in the minimum value storage unit with the rotation speed of the electric water pump, and sets a flag each time the rotation speed exceeds the sum or sets a flag each time the rotation speed falls below the sum; and an EWP rotation speed vibration determination unit that determines that the rotation speed of the electric water pump is vibrating if the ratio of the number of flags set within a predetermined unit time to the number of flags set within a time longer than the unit time is within a predetermined range.

[0008] According to the configuration (1) above, it is determined whether the rotation speed of the electric water pump is vibrating, and if it is determined that the rotation speed of the electric water pump is vibrating continuously, it is determined that a coolant water reduction abnormality has occurred in the coolant circuit into which coolant is poured, making it possible to detect that a coolant water reduction abnormality has occurred in the coolant circuit into which coolant is poured.

[0009] (2) In some embodiments, the configuration of (1) above includes a coolant water reduction abnormality determination unit that determines that a coolant water reduction abnormality has occurred in the coolant circuit when the number of times that the rotation speed of the electric water pump is determined to be vibrating reaches a predetermined number of consecutive times.

[0010] According to the configuration (2) above, by determining that a cooling water reduction abnormality has occurred in the cooling water circuit, it is possible to detect that a cooling water reduction abnormality has occurred in the cooling water circuit into which cooling water is injected.

[0011] (3) In some embodiments, in the configuration of (1) or (2) above, the unit time is a first unit time and a second unit time different from the first unit time, and the first unit time and the second unit time are switched at a predetermined timing.

[0012] According to the configuration (3) above, it is expected that the vibration characteristics (frequency and magnitude of fluctuation) of the rotation speed of the electric water pump will differ depending on the degree of water loss in the coolant circuit and the drive ratio (drive duty) of the electric water pump. Therefore, by switching between the first unit time and the second unit time at a predetermined timing, even if the degree of water loss in the coolant circuit differs or the electric water pump is driven at a different drive duty and the vibration characteristics of the rotation speed of the electric water pump change, it is possible to more efficiently and with less erroneous detection whether a coolant loss abnormality has occurred in the coolant circuit.

[0013] (4) In some embodiments, in the configuration of (2) above, a warning light illumination instruction unit is provided that instructs a warning light provided on an instrument panel to illuminate when the coolant water level reduction abnormality determination unit determines that the coolant water level reduction abnormality has occurred for more than a predetermined time.

[0014] According to the configuration (4) above, when it is determined that a cooling water low level abnormality has occurred in the cooling water circuit, an instruction is given to turn on a warning light provided on the instrument panel, and the warning light turns on, thereby enabling the user (driver) to notice that a cooling water low level abnormality has occurred in the cooling water circuit.

[0015] (5) In some embodiments, in the configuration of (2) above, an output suppression instruction unit is provided that instructs the cooling target equipment to suppress output when the cooling water reduction abnormality determination unit determines that the cooling water reduction abnormality has occurred for more than a predetermined time.

[0016] According to the configuration (5) above, when it is determined that a cooling water reduction abnormality has occurred in the cooling water circuit, the output of the equipment to be cooled is suppressed by instructing the equipment to be cooled, thereby preventing the equipment to be cooled from overheating. [Effects of the Invention]

[0017] According to at least one embodiment of the present invention, it is possible to detect the occurrence of a coolant reduction abnormality in a coolant circuit into which coolant is injected. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a diagram schematically illustrating an example of a coolant circuit according to the embodiment. [Figure 2] FIG. 2 is a diagram schematically illustrating the appearance of the capacitor tank, the electric water pump, and the drive motor shown in FIG. [Figure 3] 3 is a diagram schematically illustrating the appearance of the capacitor tank and the electric water pump shown in FIG. 2 and a cross section of the drive motor. [Figure 4]2 is a block diagram showing a schematic configuration of a drive control device that drives the drive motor, inverter, and electric water pump shown in FIG. 1. FIG. [Figure 5] FIG. 2 is a block diagram illustrating a detailed configuration of a flag setting unit according to the embodiment. [Figure 6] 10 is a diagram showing an example of the rotation speed of the electric water pump when the liquid level of the coolant stored in the condenser tank drops to a certain level (for example, 0.5 L) from the low level position. FIG. [Figure 7] FIG. 7 is a diagram showing the EWP rotation speed under the conditions of FIG. 6 and the rotation speed Nmax stored in the memory MAX. [Figure 8] FIG. 7 is a diagram showing the EWP rotation speed under the conditions of FIG. 6 and the rotation speed Nmin stored in the memory MIN. [Figure 9] FIG. 7 is a diagram showing the rotation speed Nmax stored in the memory MAX, the rotation speed Nmin stored in the memory MIN, and the rotation speed Nmid stored in the memory MID under the conditions of FIG. 6. [Figure 10] FIG. 7 is a diagram showing, by means of flags, the timing at which the EWP rotation speed under the conditions of FIG. 6 exceeds the rotation speed stored in the memory MID. [Figure 11] FIG. 7 is a diagram showing, by means of flags, the timing at which the EWP rotation speed under the conditions of FIG. 6 exceeds the rotation speed obtained by adding the rotation speed for noise prevention to the memory MID rotation speed. [Figure 12] This figure shows Vp, which indicates the ratio of the number of flags under the conditions of Figure 6, and indicates that the rotation speed of the electric water pump continues to be determined to be vibrating (the continuous occurrence of vibration determinations is accumulating), and therefore the coolant in the coolant circuit continues to be determined to be low, resulting in a state determined to be abnormal. [Figure 13] FIG. 12 shows Vp, which indicates the ratio of the flag when a flag is set when the rotation speed of the electric water pump exceeds the rotation speed stored in memory MID under the conditions of FIG. 6 plus a rotation speed for noise prevention, and also shows that the state in which the rotation speed of the electric water pump is determined to be vibrating continues for a longer period of time than under the conditions of FIG. 12, making it easier to determine that a coolant decrease abnormality is occurring than under the conditions of FIG. 12. [Figure 14]This figure shows an example of the rotation speed of an electric water pump when the liquid level of the coolant stored in the condenser tank drops below the low level (for example, 1.5 L), and shows a state in which it is determined that Vp and the rotation speed of the electric water pump are vibrating when the first set (for example, a unit time of 1 second and a time longer than the unit period of 2 seconds) is used to determine the vibration of the rotation speed. [Figure 15] 4 is a flowchart showing the control of the coolant flow rate reduction abnormality detection device for the coolant circuit. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with tolerances or angles or distances to the extent that the same function is achieved. Furthermore, expressions expressing shapes such as a rectangular or cylindrical shape not only express shapes such as a rectangular or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, expressions such as "comprise," "comprise," "include," "include," or "have" of a particular component are not exclusive expressions that exclude the presence of other components.

[0020] [Cooling water circuit] 1 is a diagram schematically illustrating an example of a coolant circuit 1 according to an embodiment. The coolant circuit 1 according to the embodiment is a coolant circuit that cools a motor and the like, and is mounted on an electrically powered vehicle such as an electric vehicle (EV). Other electrically powered vehicles include, but are not limited to, hybrid vehicles (HVs) and plug-in hybrid vehicles (PHEVs, PHVs) that can be charged from an external device (for example, an external charger) and, depending on the vehicle, can also supply power to external devices (for example, home appliances installed in a home).

[0021] As shown in FIG. 1, the coolant circuit 1 according to the embodiment is a coolant circuit in which coolant circulates through a condenser tank 11, an electric water pump (EWP) 12, an electric water pump discharge path (discharge pipe 122), and a cooled device 13 in this order.

[0022] FIG. 2 is a diagram that schematically shows the appearance of the capacitor tank 11, the electric water pump 12, and the drive motor 14 shown in FIG. 1, and FIG. 3 is a diagram that schematically shows the appearance of the capacitor tank 11 and the electric water pump 12 and a cross section of the drive motor 14 shown in FIG. 2.

[0023] As shown in FIGS. 2 and 3, condenser tank 11 is a container for storing coolant that has a function of promoting air-water separation. Condenser tank 11 has, for example, a rectangular parallelepiped shape, but is not limited to this. A water inlet for refilling the coolant is provided on the top surface of condenser tank 11. The water inlet is closed with cap 111 equipped with a pressure valve (intake / exhaust valve), and cap 111 is removed only when refilling the coolant. A coolant outlet is provided on the bottom surface of condenser tank 11 or at a position lower than the low line. As shown in FIG. 2, in this condenser tank 11, a coolant recovery port is provided on the side surface at a position higher than the center in the height direction, but the coolant recovery port can also be located on the bottom surface of condenser tank 11. A water supply pipe 112 for electric water pump 12 is connected to the coolant outlet, and a recovery pipe 113 is connected to the coolant recovery port.

[0024] Furthermore, a water gauge 114 that indicates the amount of coolant in the coolant circuit 1 is provided on the side of the condenser tank 11. For example, the water gauge 114 is a window formed by fitting a transparent plate into an opening that extends vertically on the side of the condenser tank 11, and is formed so that the level of the coolant stored in the condenser tank 11 can be seen, and scales reading "Low" and "Full" are provided next to the window, so that when the coolant level is between "Low" and "Full" after water filling has been completed according to the correct procedure, it can be confirmed that the appropriate amount of water has been poured into the coolant circuit 1. Note that, instead of providing such a window, the condenser tank 11 itself may be formed from a transparent or translucent material and have scales reading "Low" and "Full" on the condenser tank 11 itself, so that it can be visually confirmed, similar to the window, that the appropriate amount of water has been poured.

[0025] Electric water pump 12 is provided below condenser tank 11 in the direction of gravity and is connected to condenser tank 11. As shown in Fig. 3, electric water pump 12 has, for example, a cylindrical shape with an inlet provided on one of two circular planes of the cylindrical shape and an outlet provided on the outer circumferential surface. The aforementioned water supply pipe 112 is connected to the inlet, and coolant is supplied from condenser tank 11.

[0026] The electric water pump discharge path (discharge pipe 122) is connected to the discharge port of electric water pump 12 and extends upward in the direction of gravity relative to electric water pump 12.

[0027] The equipment 13 to be cooled is, for example, a drive motor 14 and an inverter 15 of an electric vehicle as shown in Figs. 1 to 3, but is not limited to this. In this embodiment, the illustrated state is that the cooled equipment 13, such as the drive motor 14 of an electric vehicle, is located above the electric water pump 12 in the direction of gravity and is connected to the electric water pump 12. However, any structure that causes the coolant to backflow or stagnate in the discharge pipe 122 when the coolant level decreases is sufficient. In order to create a state in which the rotation speed of the electric water pump 12 can be said to be oscillating due to the volume of coolant in the discharge pipe 122, or to create a state in which the rotation speed of the electric water pump 12 can be said to be oscillating, a component (such as a tank, a long hose, or a thick hose) having the capacity to store the required amount of coolant is provided between the discharge pipe 122 and the cooled equipment 13, such as the drive motor 14. In this case, the cooled equipment 13, such as the drive motor 14, is not directly connected to the discharge pipe 122, but is connected to the discharge pipe 122 via a component (such as a tank, a long hose, or a thick hose) having the capacity to store the required amount of coolant. In this case, the height of the cooled equipment 13, such as the drive motor 14, may be the same height as the electric water pump or may be below the electric water pump in the direction of gravity.

[0028] The drive motor 14 has, for example, a cylindrical shape and is provided with a cooling water inlet and a cooling water outlet on its outer surface. The aforementioned discharge pipe 122 is connected to the cooling water inlet, and the cooling water discharged from the electric water pump 12 is supplied to the cooling water inlet. The cooling water supplied to the cooling water inlet of the drive motor 14 passes through a water passage 142 provided in a motor housing 141 of the drive motor 14, whereby the cooling water removes heat from the drive motor 14 (by exchanging heat with the cooling water) and then exits from the cooling water outlet. A pipe 143 is connected to the cooling water outlet, and the cooling water exiting the drive motor 14 passes through the pipe 143 and is supplied to the next device 13 to be cooled, for example, the inverter 15.

[0029] 1 , the coolant circuit 1 according to the embodiment is provided with a radiator 16 between the device to be cooled 13 and the condenser tank 11. The device to be cooled 13 is, for example, an inverter 15, and the coolant discharged from the inverter 15 passes through the radiator 16 and is collected in the condenser tank 11. A pipe 143 connected to the coolant outlet of the inverter 15 is connected to the coolant inlet of the radiator 16, and the above-mentioned collection pipe 113 is connected to the coolant outlet of the radiator 16. As a result, the coolant discharged from the inverter 15 passes through the radiator 16 and is collected in the condenser tank 11.

[0030] The radiator 16 is a heat exchanger that radiates the heat of the coolant to the surrounding air, and is provided behind the radiator 16 with a radiator fan 17. When the coolant becomes hot, the radiator fan 17 is operated to pass outside air through the radiator 16 at a higher speed, and more of the heat of the coolant is radiated to the outside air in the radiator 16.

[0031] [Drive control device] Fig. 4 is a block diagram showing a schematic configuration of the drive control device 2 that drives the drive motor 14, inverter 15, and electric water pump 12 shown in Fig. 1. As shown in Fig. 4, the drive motor 14 is connected to the drive control device 2 via the inverter 15 and is indirectly controlled via the inverter 15. The drive control device 2 is provided in, for example, an ECU 3 that controls the electric vehicle. The ECU 3 is made up of, for example, a processor made up of an arithmetic unit, registers that store instructions and information, and peripheral circuits, memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an input / output interface.

[0032] An accelerator position sensor 32 (hereinafter referred to as "APS 32") that detects the depression amount of an accelerator pedal 31 (accelerator opening) is connected to the ECU 3, and a motor drive torque instruction unit 33 is provided in the ECU 3. The motor drive torque instruction unit 33 instructs the inverter 15 on the motor drive torque to be generated by the drive motor 14 based on the motor rotation speed obtained from a motor rotation speed calculation unit 151 (described later) and the accelerator opening detected by the APS 32.

[0033] The inverter 15 is provided with a motor rotation speed calculation unit 151, a motor drive torque calculation unit 152, and a motor energization unit 153. The motor rotation speed calculation unit 151 calculates the motor rotation speed from information from a motor rotation angle measurement unit 145 provided in the drive motor 14, which will be described later, and the motor drive torque calculation unit 152 controls the motor energization unit 153 based on the motor drive torque indicated by the motor drive torque indication unit 33, thereby controlling the energization of the stator coil 144 of the drive motor 14.

[0034] The drive motor 14 is provided with a motor rotation angle measurement unit 145. The motor rotation angle measurement unit 145 measures the rotation angle of the motor output shaft and notifies the rotation angle to a motor rotation speed calculation unit 151 of the inverter 15. The motor rotation speed calculation unit 151 uses the rotation angle to calculate the motor rotation speed and notifies a motor drive torque calculation unit 152 and a motor drive torque instruction unit 33 of the ECU 3. The drive motor 14 is also provided with a temperature sensor 146 (hereinafter referred to as the "first temperature sensor 146"). The first temperature sensor 146 measures the temperature of the drive motor 14 and notifies a required coolant flow rate calculation unit 154 provided in the inverter 15 of the temperature.

[0035] The inverter 15 is also provided with a temperature sensor 155 (hereinafter referred to as the "second temperature sensor 155"). The second temperature sensor 155 measures the temperature of the inverter 15 and notifies the temperature to a required coolant flow rate calculation unit 154 provided in the inverter 15. The required coolant flow rate calculation unit 154 calculates the required coolant flow rate to be circulated through the coolant circuit 1 including the drive motor 14 and the inverter 15 based on the temperature notified from the first temperature sensor 146 and the temperature notified from the second temperature sensor 155, and notifies the calculated amount to an EWP drive duty calculation unit 21 of the ECU 3, which will be described later. The EWP drive duty calculation unit 21 calculates the EWP drive duty by combining the temperature of the coolant circulating through the coolant circuit 1 from a water temperature sensor 34 (described later) and the coolant flow rate required by each of the cooled devices 13, and transmits this to an EWP drive duty instruction unit 22 (described later) to circulate the flow rate required by the cooled device through the coolant circuit 1 including the drive motor 14 and the inverter 15. Note that in the example of the coolant circuit 1, the cooled device 13 is only the drive motor 14 and the inverter 15, but the inverter 15 combines the coolant flow rates required by the drive motor 14 and the inverter 15 itself and transmits this to the EWP drive duty calculation unit 21.

[0036] The ECU 3 (engine control device 2) is also connected to the electric water pump 12 and a water temperature sensor 34. The electric water pump 12 is an electric water pump whose drive ratio (drive duty) can be controlled by PWM (Pulse Width Modulation), and the drive ratio (drive duty) is instructed by the ECU 3. The water temperature sensor 34 is installed, for example, on the drive motor 14 (on the coolant inlet side of the drive motor 14) or the inverter 15 (on the coolant inlet side of the inverter 15), but may be installed at any position where the temperature of the coolant in the coolant circuit 1 can be measured.

[0037] The ECU 3 (engine control device 2) is provided with an EWP drive duty calculation unit 21 and an EWP drive duty instruction unit 22. The EWP drive duty calculation unit 21 calculates the EWP drive duty for driving the electric water pump 12 based on the required coolant flow rate calculated by the required coolant flow rate calculation unit 154 and the water temperature measured by the water temperature sensor 34, and the EWP drive duty instruction unit 22 instructs an EWP drive duty to an EWPDuty drive unit 123 provided in the electric water pump 12. As a result, the EWPDuty drive unit 123 provided in the electric water pump 12 drives the electric water pump 12 so as to achieve the drive ratio of the instructed EWP drive duty.

[0038] Electric water pump 12 is provided with an electric water pump rotation speed measurement unit (also referred to as an EWP rotation speed measurement unit) 41. EWP rotation speed measurement unit 41 measures the rotation speed of electric water pump 12. The rotation speed is measured in units of, for example, rotations per minute, expressed in rev / min (rpm).

[0039] [Vibration of the electric water pump rotation speed when the coolant level in the coolant circuit is low] The present inventors have discovered that when the amount of coolant supplied to the above-described coolant circuit 1 becomes low, the rotation speed of electric water pump 12 fluctuates regularly, resulting in a state that can be considered vibration. The present inventors have therefore come up with the idea of ​​detecting a coolant low level abnormality due to a coolant leak or the like in coolant circuit 1 by determining whether the fluctuations in the rotation speed of electric water pump 12 can be considered vibration and whether the state that can be considered vibration continues.

[0040] [Configuration of cooling water circuit cooling water reduction abnormality detection device] The coolant low level abnormality detection device 4 of the coolant circuit 1 includes an electric water pump rotation speed measurement unit 41, a flag setting unit 42, an EWP rotation speed vibration determination unit 43, and a coolant low level abnormality determination unit 44.

[0041] [Electric water pump rotation speed measurement unit] Electric water pump rotation speed measuring unit 41 is configured to measure the rotation speed of electric water pump 12.

[0042] [Flag setting section] When the rotation speed of electric water pump 12 fluctuates so as to repeatedly have maximum and minimum points, flag setting unit 42 is configured to set a flag each time the rotation speed of electric water pump 12 exceeds, or each time the rotation speed of electric water pump 12 falls below, a rotation speed obtained by dividing the sum of the maximum value when the rotation speed of electric water pump increases (when the rotation speed of electric water pump decreases, the maximum value before the rotation speed of electric water pump starts to decrease is maintained (the maintained maximum value corresponds to the maximum value)) and the minimum value when the rotation speed of electric water pump decreases (when the rotation speed of electric water pump increases, the minimum value before the rotation speed of electric water pump starts to increase is maintained (the maintained minimum value corresponds to the minimum value)), in half. Flag setting unit 42 is provided in, for example, the drive control device 2 described above.

[0043] 5 is a block diagram schematically showing a detailed configuration of the flag setting unit 42 according to the embodiment. As shown in FIG. 5, the flag setting unit 42 according to the embodiment includes a maximum value storage unit 421, a minimum value storage unit 422, and a binary value storage unit 423.

[0044] Maximum value storage unit 421 is a storage unit that updates and stores the maximum value when the rotation speed measured by electric water pump rotation speed measurement unit 41 increases. As the rotation speed measured by electric water pump rotation speed measurement unit 41 gradually increases, the value in maximum value storage unit 421 is updated as the maximum value when the rotation speed increases (the value stored in maximum value storage unit 421 gradually increases). Then, when the rotation speed measured by electric water pump rotation speed measurement unit 41 changes from increasing to decreasing, the maximum value at the time of this change is maintained in maximum value storage unit 421 (in other words, the maximum value stored in maximum value storage unit 421 remains unchanged), even though the rotation speed measured by electric water pump rotation speed measurement unit 41 decreases. This maintained rotation speed corresponds to the local maximum value.

[0045] Minimum value storage unit 422 is a storage unit that updates and stores the minimum value when the rotation speed measured by electric water pump rotation speed measurement unit 41 decreases. When the rotation speed measured by electric water pump rotation speed measurement unit 41 gradually decreases, the value in minimum value storage unit 422 is updated as the minimum value when the rotation speed decreases (the value stored in minimum value storage unit 422 gradually decreases). When the rotation speed measured by electric water pump rotation speed measurement unit 41 changes from decreasing to increasing, the minimum value at the time of this change is maintained in minimum value storage unit 422 (i.e., the minimum value stored in minimum value storage unit 422 does not change), even though the rotation speed measured by electric water pump rotation speed measurement unit 41 increases. This maintained rotation speed corresponds to a minimum value.

[0046] Incidentally, regarding maximum value memory unit 421, the maximum value (= maximum value) stored in maximum value memory unit 421 when the rotation speed of the electric water pump is decreasing changes so that the gradually increasing rotation speed is stored as a new maximum value, as if the maximum value (= maximum value) stored in maximum value memory unit 421 was reset, the next time the rotation speed of electric water pump 12 changes from decreasing to increasing after the maximum value was stored.

[0047] Similarly, to add a bit more about minimum value memory unit 422, the minimum value (= minimum value) stored in minimum value memory unit 422 when the rotation speed of the electric water pump increases changes so that the gradually decreasing rotation speed is stored as the new minimum value the next time the rotation speed of electric water pump 12 changes from increasing to decreasing after storing that minimum value, as if the minimum value (= minimum value) stored in minimum value memory unit 422 is reset.

[0048] The flag setting unit 42 according to this embodiment has a maximum value memory unit 421 (hereinafter referred to as "memory MAX"), a minimum value memory unit 422 (hereinafter referred to as "memory MIN"), and a binary value memory unit 423 (hereinafter referred to as "memory MID") that stores the rotation speed obtained by dividing the sum of the rotation speed stored in memory MAX and the rotation speed stored in memory MIN by two.

[0049] 11, when the rotation speed N of the electric water pump 12 changes from decreasing to increasing, the rotation speed N of the electric water pump 12 changes from being smaller than the binary value stored in the memory MID to being larger than the binary value stored in the memory MID. In this way, the rotation speed N of the electric water pump 12 changes from being smaller than the binary value stored in the memory MID to being larger than the binary value stored in the memory MID, so that a flag can be set at this timing (= when the minimum value occurs).

[0050] 11, when the rotation speed N of the electric water pump 12 changes from being greater than the binary value stored in the memory MID to being smaller than the binary value stored in the memory MID, a flag can be set at this timing (i.e., when a maximum value occurs).

[0051] In addition, when the rotation speed of the electric water pump 12 fluctuates so as to repeatedly change between maximum and minimum values, the flag setting unit 42 may set a flag both when the rotation speed N of the electric water pump 12 exceeds the dichotomous value stored in the memory MID (= when a minimum value occurs) and when it falls below the dichotomous value (= when a maximum value occurs).

[0052] Furthermore, since the rotation speed of electric water pump 12 has maximum and minimum values ​​even for noise-like fluctuations of less than 10 rpm, when determining whether the rotation speed of electric water pump 12 is vibrating, a flag may be raised due to noise-like fluctuations in the rotation speed of electric water pump 12, which are of a scale that is essentially different from whether the rotation speed of electric water pump 12 is fluctuating regularly.However, in order to prevent the generation of a flag that captures such minute fluctuations as noise, it is possible to improve the accuracy of the determination by adding or subtracting a small rotation speed (for example, 10 rpm) to or from memory MID.

[0053] 6 is a diagram showing the rotation speed N of electric water pump 12 (hereinafter referred to as "EWP rotation speed") input from electric water pump rotation speed measurement unit 41 to flag setting unit 42 under conditions where the coolant level stored in condenser tank 11 has dropped by a certain amount (for example, 0.5 L) from the low level. FIG. 6 shows a case where a coolant level drop abnormality has occurred in coolant circuit 1, and EWP rotation speed N fluctuates so as to regularly repeat maximum and minimum values. In the example shown in FIG. 6, EWP rotation speed N is input from electric water pump rotation speed measurement unit 41 to flag setting unit 42 every 0.01 seconds, but the interval at which EWP rotation speed N is input is not limited to 0.01 seconds.

[0054] Fig. 7 is a diagram showing the EWP rotation speed N shown in Fig. 6 and the rotation speed Nmax stored in memory MAX. As shown in Fig. 7, when the EWP rotation speed N is fluctuating and the EWP rotation speed N begins to increase, the value of Nmax is updated to the value after the increase, so that when the EWP rotation speed N increases, the value of Nmax = the EWP rotation speed N. Then, when the EWP rotation speed N passes the maximum point of the fluctuation peak and begins to decrease, the value is no longer updated, so that memory MAX stores and maintains the maximum value at each peak of the fluctuation of the EWP rotation speed N until the EWP rotation speed N begins to increase again.

[0055] FIG. 8 is a diagram showing the EWP rotation speed N shown in FIG. 6 and the rotation speed Nmin stored in memory MIN. As shown in FIG. 8, when the EWP rotation speed N is fluctuating and the EWP rotation speed N begins to decrease, the value of Nmin stored in memory MIN is updated to the value after the decrease, so that when the EWP rotation speed decreases, the value of Nmin = EWP rotation speed N. Then, when the EWP rotation speed N passes the minimum point in the valley of its fluctuation and begins to increase, the value is no longer updated. Therefore, until the EWP rotation speed next begins to decrease, memory MIN stores and maintains the minimum value at each valley of the fluctuation of EWP rotation speed N. Note that when electric water pump 12 starts operating from a stopped state, Nmin = 0 (initial value) until the EWP rotation speed N passes the first maximum point.

[0056] Figure 9 is a diagram showing the rotation speed Nmax stored in memory MAX, the rotation speed Nmin stored in memory MIN, and the rotation speed Nmid stored in memory MID under the conditions of Figure 6. As shown in Figure 9, the change in rotation speed Nmid is Nmid = (Nmax + Nmin) / 2, so when EWP rotation speed N increases, EWP rotation speed N = Nmax, and because Nmin maintains the immediately previous minimum value, Nmid is the sum of the EWP rotation speed N and the minimum value (Nmin) at the start of the increase divided by 2, so Nmid is a value smaller than EWP rotation speed N, but as soon as EWP rotation speed N reaches the maximum value and decreases very slightly, Nmin is updated and the maximum value = Nmax ≈ N = Nmin = almost the maximum value, so Nmid = (Nmax + Nmin) / 2 = (maximum value + almost the maximum value) / 2, and so Nmid becomes almost the maximum value. On the other hand, when EWP rotation speed N is decreasing, Nmid = (Nmax + Nmin) / 2, so EWP rotation speed N = Nmin, and because Nmax is maintained at its previous maximum value, it is calculated by adding the EWP rotation speed N and the maximum value (Nmax) at the time the decrease started and dividing the sum by 2, so Nmid is a value greater than the EWP rotation speed N, but as soon as it reaches the minimum value and the EWP rotation speed N increases ever so slightly, Nmax is updated and the minimum value = Nmin ≒ N = Nmax = almost the minimum value, and therefore Nmid = (Nmax + Nmin) / 2 = (minimum value + almost minimum value) / 2, so Nmid becomes almost the minimum value. As can be seen from Figure 9, the EWP rotation speed N and Nmid intersect immediately after the maximum and minimum values, switching between large and small values, so a flag is set when the EWP rotation speed N exceeds Nmid, or a flag is set when the EWP rotation speed N falls below Nmid, or a flag is set when the EWP rotation speed N exceeds and falls below N. Then, by counting these flags, it is possible to determine the number of peaks or troughs in the fluctuations in the EWP rotation speed N per unit time, or the number of both peaks and troughs.

[0057] 10 is a diagram showing the EWP rotation speed N shown in FIG. 6, the rotation speed Nmid stored in memory MID, and a flag set when the EWP rotation speed N shown in FIG. 6 exceeds the rotation speed Nmid stored in memory MID. As described above, for example, flag setting unit 42 may set a flag when the rotation speed N of electric water pump 12 exceeds a median rotation speed Nmid obtained by dividing the sum of Nmax and Nmin in half. Although not shown in FIG. 10, a flag may be set when the rotation speed N of electric water pump 12 falls below the median rotation speed Nmid obtained by dividing the sum of Nmax and Nmin in half, or a flag may be set both when the rotation speed N exceeds and when it falls below the median rotation speed Nmid.

[0058] FIG. 11 illustrates a timing when a flag is set when the EWP rotation speed N shown in FIG. 6 exceeds Nmid+α, which is the rotation speed stored in memory MID plus a rotation speed α to prevent a flag from being set due to noise-like fluctuations in rotation speed N of, for example, less than 10 rpm. The rotation speed α to prevent a flag from being set due to noise-like fluctuations in rotation speed N is, for example, 10 revolutions (10 rpm). By adding 10 rpm to prevent a flag from being set due to noise-like fluctuations in rotation speed N of, for example, less than 10 rpm, it is possible to prevent a noise-like flag from being set due to fluctuations in EWP rotation speed N of less than 10 rpm. Therefore, as described above, a flag may be set when the rotation speed N of electric water pump 12 exceeds Nmid, which is the sum of a small rotation speed α (for example, 10 rpm) added to prevent a flag from being set due to noise-like fluctuations in rotation speed N of, for example, less than 10 rpm. Although not shown in FIG. 11, a flag may be set when the rotation speed N of the electric water pump 12 falls below a middle rotation speed Nmid, which is obtained by dividing the sum of Nmax and Nmin in half, or a flag may be set both when the rotation speed N exceeds the middle rotation speed Nmid and when the rotation speed N falls below the middle rotation speed Nmid.

[0059] [EWP rotational speed vibration detection unit] EWP rotation speed vibration determination unit 43 is configured to determine that the rotation speed of electric water pump 12 is vibrating when the ratio of the number of flags set within a predetermined unit time to the number of flags set within a time longer than the unit time is within a predetermined range. EWP rotation speed vibration determination unit 43 is provided in, for example, the drive control device 2 described above.

[0060] The unit time and the time longer than the unit time can be set arbitrarily, and the time longer than the unit time is, for example, twice the unit time, but is not limited to this and may be 1.5 times the unit time or three times the unit time. The unit time is, for example, 1 second, and the time longer than the unit time is, for example, 2 seconds, but is not limited to this and may be 2 seconds and 6 seconds, respectively.

[0061] The unit time may be, for example, a first unit time or a second unit time different from the first unit time, and may be switched at any timing, but may also be switched periodically or periodically. The second unit time may be, for example, twice the length of the first unit time, but is not limited to this and may be 0.5 or 3 times the length of the first unit time. Furthermore, the second unit time is not limited to one, but may be two or more.

[0062] The above-mentioned unit time and the time longer than the unit time form a set of two, and not only one such set but also multiple sets can be set. For example, in one set, the unit time (the first unit time) is 1 second, and the time longer than the unit time is 2 seconds. In another set, the unit time (the second unit time) is 3 seconds, and the time longer than the unit time is 6 seconds, but it is not limited to this. Note that the first set has a shorter determination period and is more efficient in detecting abnormal reduction of cooling water. The second set has a longer determination period, but in that case, false detection can be more effectively prevented. Thus, for each cooling water circuit and for each specification and setting of the electric water pump 12, one or multiple arbitrary sets can be set. When multiple sets are set, by switching the set at a predetermined timing, the determination can be made more efficient or false detection can be more effectively prevented.

[0063] For example, if the time longer than the unit time is set to twice the unit time, the number of flags set within the unit time is CSA, and the number of flags set within the time longer than the unit time is CSB, then Vp (CSB / CSA), which is the ratio of the number of flags set within the time longer than the unit time to the number of flags set within the unit time, is set based on experiments or the like with 2.0, which is the ratio of the times, as a reference.

[0064] FIG. 12 is a diagram showing the rotational speed of the electric water pump 12 under the conditions of FIG. 6, and is a diagram showing Vp (CSB / CSA) when the unit time is 3 seconds and the time longer than the unit time is 6 seconds. As shown in FIG. 12, in this example, when Vp varied within the range from 1.4 to 3.1 based on 2.0, it was determined that the rotational speed of the electric water pump 12 had regular fluctuations, that is, it was vibrating. Therefore, in this example, by setting Vp to 1.4 < Vp < 3.1, it is possible to determine whether the rotational speed of the electric water pump 12 is vibrating.

[0065] FIG. 13 is a diagram showing the number of flags counted after adding a slight rotational speed (e.g., 10 rpm) for noise prevention to the memory that stores the median EWP rotational speed, at a location that is essentially different from the regular EWP fluctuations described in FIG. 12, for example, fluctuations in the EWP rotational speed of less than 10 rpm, in order to prevent the generation of noisy flags. By adding a slight rotational speed (10 rpm) for noise prevention, the generation of noisy flags can be prevented. When the flag is set at the timing when the rotational speed N of the electric water pump 12 exceeds Nmid added with a slight rotational speed (e.g., 10 rpm) for noise prevention, the calculated Vp is in the range from 1.4 to 3.1 based on 2.0, and the state where this continues (the state where continuous occurrences of vibration determination are accumulated) is extended compared to the case of FIG. 12.

[0066] FIG. 14 is a diagram showing the rotational speed of the electric water pump 12 when the amount of cooling water stored in the capacitor tank 11 is reduced by a relatively large amount (e.g., 1.5 L) beyond the position where the liquid level becomes Low, and is a diagram showing Vp (CSB / CSA) when the unit time is 1 second and the time longer than the unit time is 2 seconds. As shown in FIG. 14, in this example, when Vp fluctuates in the range from 1.7 to 2.3 based on 2.0 which is the ratio of time, it can be determined that the EWP rotational speed has regular fluctuations, that is, it is vibrating. Therefore, in this example, by setting 1.7 < Vp < 2.3, it is possible to determine whether the rotational speed of the electric water pump 12 is vibrating.

[0067] [Cooling water reduction abnormality determination unit] Furthermore, the coolant low level anomaly detection device 4 for the coolant circuit 1 according to this embodiment includes a coolant low level anomaly determination unit 44, but this is not an essential component because it is possible to determine whether a coolant low level has occurred in the coolant circuit 1 if the EWP rotation speed vibration determination unit 43 determines whether the rotation speed of the electric water pump 12 is vibrating. The coolant low level anomaly determination unit 44 is configured to determine that a coolant low level anomaly has definitely occurred in the coolant circuit 1 when the cumulative number of times that the rotation speed of the electric water pump 12 has been determined to be vibrating reaches a predetermined number. This further prevents erroneous determinations. The coolant low level anomaly determination unit 44 is provided, for example, in the drive control device 2 described above.

[0068] In the above-described embodiment, if the cumulative number of times that the rotation speed of the electric water pump 12 is determined to be vibrating continuously without interruption reaches a predetermined number, it is determined that a coolant loss abnormality has definitely occurred in the coolant circuit 1. However, even if the determination that the rotation speed is vibrating is interrupted, it may also be determined that a coolant loss abnormality has occurred in the coolant circuit 1 if the cumulative number of times reaches a predetermined number when the rate is below a predetermined value (for example, below 20%).

[0069] 12 also shows the cumulative number of times that the fluctuation in the rotation speed of electric water pump 12 has continued without interruption to be determined to be vibrating. In the example shown in FIG. 12, a new rotation speed of electric water pump 12 is input from electric water pump rotation speed measurement unit 41 to flag setting unit 42, for example, every 0.01 seconds (i.e., updated to the rotation speed newly obtained from EWP). Therefore, after a time longer than the unit time (3 seconds in this example) (6 seconds in this example) has elapsed, CSA and CSB are updated every 0.01 seconds, and whether or not vibration is occurring can be determined every 0.01 seconds based on Vp. In this example, the predetermined number is 500 times. If it is determined that electric water pump 12 has vibrated 500 times in a row without interruption, coolant level decrease abnormality determination unit 44 determines that an abnormality such as a continuous decrease in the coolant level has occurred in coolant circuit 1. In this example, the vibration occurs 500 times continuously every 0.01 seconds, so the time required to make this determination is 5 seconds, and since the unit time and times longer than the unit time can be measured simultaneously, it is possible to determine conclusively whether or not a coolant low level abnormality has occurred in the coolant circuit 1 in a minimum of 11 seconds (time longer than the unit time: 6 seconds + period required to determine that vibrations are occurring 500 times continuously: 5 seconds).

[0070] FIG. 13 shows a state in which a small noise prevention rotation speed (for example, 10 rpm) is added to memory MID, which stores a medium EWP rotation speed, in order to prevent the generation of a flag that would be raised as noise due to EWP rotation speed fluctuations of less than 10 rpm, for example, at a location that is essentially different from the regular EWP fluctuations described in FIG. 12 . By adding the small noise prevention rotation speed, the generation of a flag that would be raised as noise due to EWP rotation speed fluctuations N of less than 10 rpm, for example, is prevented. FIG. 13 also shows the number of times (cumulative) that it has been determined that the rotation speed fluctuations of electric water pump 12 are vibrating, when a flag is raised when the rotation speed N of electric water pump 12 exceeds Nmid, which is the value obtained by adding the small noise prevention rotation speed (10 rpm). According to this figure, the duration of the state in which the calculated Vp is in the range of 1.4 to 3.1, with 2.0 as the base, is longer than in Figure 12, so in this example, it is possible to confirm a cooling water low level abnormality even if the number of consecutive times required to confirm the abnormality is increased beyond 500, making it possible to further prevent erroneous determinations.

[0071] 12 and 13, Fig. 14 also shows the cumulative number of times that the fluctuation in the rotation speed of electric water pump 12 has been determined to be vibrating. In the example shown in Fig. 14, a new rotation speed of electric water pump 12 is input from electric water pump rotation speed measurement unit 41 to the flag determination unit, for example, every 0.01 seconds (i.e., updated to a new rotation speed obtained from EWP). Therefore, after a time longer than a unit time (1 second in this example) (2 seconds in this example) has elapsed, CSA and CSB are updated every 0.01 seconds, and whether or not vibration is occurring can be determined based on Vp every 0.01 seconds. In this example, the predetermined number of times is 500. If electric water pump 12 is determined to have vibrated 500 times in a row without interruption, coolant level decrease abnormality determination unit 44 determines that a continuous decrease in the coolant level in coolant circuit 1 has occurred. In this example, too, the vibration occurs 500 times continuously every 0.01 seconds, so the time required to make this determination is 5 seconds, and since the unit time and times longer than the unit time can be measured simultaneously, it is possible to determine conclusively whether or not a coolant low level abnormality has occurred in the coolant circuit 1 in a minimum of 7 seconds (time longer than the unit time: 2 seconds + period required to determine that vibrations are occurring 500 times continuously: 5 seconds).

[0072] [Warning light lighting instruction section] 4, the coolant level reduction anomaly detection device 4 of the cooling system according to the embodiment includes a warning light illumination instruction unit 45 that instructs a warning light 51 provided on the instrument panel 5 to illuminate when the coolant level reduction anomaly determination unit 44 determines that a coolant level reduction anomaly has occurred for more than a predetermined time. However, this is not an essential component, as the coolant level reduction anomaly determination unit 44 is a prerequisite. The warning light illumination instruction unit 45 is provided in the drive control device 2, for example.

[0073] [Output suppression instruction section] Furthermore, the cooling water reduction anomaly detection device 4 for the cooling device according to the embodiment includes an output suppression instruction unit 46 that instructs the cooled target equipment 13 to suppress output when the cooling water reduction anomaly determination unit 44 determines that a cooling water reduction anomaly has occurred for more than a predetermined time, but this is not an essential component since it is a prerequisite that the cooling water reduction anomaly determination unit 44 is provided. The output suppression instruction unit 46 is provided in the drive control device 2 described above, for example.

[0074] [Control details of the cooling water circuit cooling water reduction abnormality detection device] Fig. 15 is a flowchart showing the control contents of the coolant decrease abnormality detection device 4 of the coolant circuit 1. As shown in Fig. 15, the coolant decrease abnormality detection device 4 of the coolant circuit 1 resets the values ​​of the memory used for calculation and control of the flag setting unit 42, the EWP rotation speed vibration determination unit 43, and the coolant decrease abnormality determination unit 44 (step S11). This initializes the coolant decrease abnormality detection device 4 of the coolant circuit 1.

[0075] Next, flag setting unit 42 acquires the rotation speed N of electric water pump 12 (hereinafter referred to as "EWP rotation speed N") measured by electric water pump rotation speed measurement unit 41, and stores EWP rotation speed N in memory N0 (N zero) provided in flag setting unit 42 (step S21). Next, to count the number of calculations, flag setting unit 42 increments calculation number counter C provided in flag setting unit 42 by 1 and stores the count (step S22). Next, flag setting unit 42 acquires a new EWP rotation speed N measured by electric water pump rotation speed measurement unit 41, and stores the newly acquired EWP rotation speed N in memory N1 provided in flag setting unit 42 (step S23).

[0076] Next, the flag setting unit 42 compares the EWP rotation speed N0 stored in memory N0 (N-zero) with the EWP rotation speed N1 stored in memory N1 (step S24). If the EWP rotation speed N1 stored in memory N1 is higher than the EWP rotation speed N0 stored in memory N0 (N-zero), the EWP rotation speed N1 is stored in memory MAX as Nmax (step S25). At this time, the value (rotation speed) previously stored in memory MIN is maintained as the value of Nmin (memory MIN) (initial value is a reset value, e.g., 0). If the EWP rotation speed N stored in memory N1 is lower than the EWP rotation speed stored in memory N0, the EWP rotation speed N stored in memory N1 is stored as Nmin in memory MIN provided in the flag setting unit 42 (step S26). At this time, the value (rotation speed) previously stored in memory MAX is maintained as the value of Nmax (memory MAX) (initial value is a reset value, e.g., 0). If the EWP rotation speed stored in memory N1 is the same as the EWP rotation speed stored in memory N0, the values ​​stored immediately before (memory MAX, memory MIN) are maintained for both memory MAX and memory MIN. Then, the sum of the EWP rotation speed Nmax stored in memory MAX and the EWP rotation speed Nmin stored in memory MIN is divided in half to calculate a mid-range rotation speed Nmid, which is stored in memory MID provided in flag setting unit 42 (step S27).

[0077] Next, the flag setting unit 42 determines whether the EWP rotation speed N1 acquired in memory N1 exceeds the rotation speed Nmid stored in memory MID (step S28). If the rotation speed N stored in memory N1 exceeds the rotation speed Nmid stored in memory MID, the flag setting unit 42 sets the EWP rotation speed comparison state to state 1 (step S29). On the other hand, if the EWP rotation speed N stored in memory N1 does not exceed the rotation speed Nmid stored in memory MID, the flag setting unit 42 recognizes that the EWP rotation speed N stored in memory N1 is the same as or lower than the rotation speed Nmid stored in memory MID, and sets the EWP rotation speed comparison state to state 0 (step S30).

[0078] Next, the flag setting unit 42 determines whether the EWP rotation speed comparison state has changed from state 0 to state 1 (step S31). If the state has changed from state 0 to state 1, the flag set by the flag setting unit 42 is set to F=1 when state 0 becomes state 1 (step S32). On the other hand, if state 0 has not changed to state 1, that is, if state 0 remains state 0, state 1 remains state 1, or state 1 has changed to state 0, the flag set by the flag setting unit 42 is set to F=0 (step S33).

[0079] Next, the EWP rotation speed vibration determination unit 43 counts the number of flags (F=1) within the unit time and stores the counted number of flags in memory CSA provided in the EWP rotation speed vibration determination unit 43 (step S41). The EWP rotation speed vibration determination unit 43 also counts the number of flags (F=1) within a time longer than the unit period (for example, twice the unit time) and stores the counted number of flags in memory CSB provided in the EWP rotation speed vibration determination unit 43 (step S42).

[0080] Next, the EWP rotational speed vibration determination unit 43 determines whether the ratio Vp of the number of flags stored in memory CSB to the number of flags stored in memory CSA (number of flags stored in memory CSB / number of flags stored in memory CSA) is within a predetermined range (step S43). The predetermined range is a range based on 2.0, which is the ratio of times when the time longer than the unit time is twice the unit time. In the above example, the unit time is 3 seconds, the time longer than the unit time is 6 seconds, and the predetermined range of the ratio of the number of flags is 1.4 to 3.1 (1.4 < predetermined range < 3.1) based on 2.0. In another example, the unit time is 1 second, the time longer than the unit time is 2 seconds, and the predetermined range of the ratio Vp of the number of flags is 1.7 to 2.3 (1.7 < predetermined range < 2.3) based on 2.0.

[0081] If the ratio Vp(CSB / CSA) of the number of flags stored in memory CSB to the number of flags stored in memory CSA is within a predetermined range, EWP rotation speed vibration determination unit 43 determines that the rotation speed of electric water pump 12 is vibrating (step S44), and if it is not within the predetermined range, it determines that it cannot be said that the rotation speed of electric water pump 12 is vibrating (step S45). Next, if it is determined in step S53 that the number of calculations has not reached the upper limit, the current value of the rotation speed memory is replaced with the old value (N0=N1: the value of memory N1 is assigned to memory N0) in step S54, and the process returns to step S22. If it is determined in step S53 that the number of calculations has reached the upper limit, the set values ​​directly related to the determination of whether the EWP rotation speed is vibrating (the unit time and the range of Vp within which it is considered that the EWP rotation speed is vibrating) are changed in step S55, and the values ​​of the memories not directly related to the determination (the memory (C) for the number of calculations and the memories related to the calculations (CSA, CSB, Vp)) are initialized, and the process returns to S21, and the series of controls is repeated from step S22 or step S21.

[0082] Next, coolant low level abnormality determination unit 44 determines whether the number of times it has been determined that the rotation speed of electric water pump 12 is vibrating has reached a predetermined number (step S51). As described above, the predetermined number is, for example, 500 times. As described above, if rotation speed N of electric water pump 12 is obtained every 0.01 seconds, it takes 5 seconds for the number of times it has been determined that the rotation speed of electric water pump 12 is vibrating to reach 500 consecutive times.

[0083] When the number of consecutive, uninterrupted determinations (cumulative total) that the rotation speed of electric water pump 12 is vibrating reaches a predetermined number, coolant level reduction abnormality determination unit 44 determines that an abnormality such as a continuing coolant level reduction has occurred in coolant circuit 1 (step S52). On the other hand, when the number of consecutive, uninterrupted determinations (cumulative total) that the rotation speed of electric water pump 12 is vibrating does not reach the predetermined number, it determines that a coolant level reduction has occurred but is not considered to be an abnormality, and then determines whether the number of calculations has reached an upper limit (step S53). The processing in step S53 is as described above. Note that the upper limit of the number of calculations is an arbitrary set number (number of times), and each time the upper limit of the number of calculations is reached, a set value directly related to the determination of whether the EWP rotation speed is vibrating is changed, and memory not directly related to the determination is initialized. The set values ​​directly related to the vibration determination of the EWP rotation speed are the unit times constituting the unit time group and the time longer than the unit times, and the Vp range for determining that the EWP rotation speed is vibrating, and the memories not directly related to the vibration determination are the memory (C) for the number of calculations and the memories (CSA, CSB, Vp) used for the calculation (step S55).

[0084] If the number of calculations has not reached the upper limit, the process returns to step S22 via step S54, and the series of controls is repeated from step S22. On the other hand, if the number of calculations has reached the upper limit, the process returns to step S21 via step S55, and the series of controls is repeated from step S21.

[0085] Next, when the coolant level reduction abnormality determination unit 44 determines that a coolant level reduction abnormality has occurred in the coolant circuit 1, the warning light illumination instruction unit 45 instructs the warning light provided on the instrument panel to illuminate (step S61). This allows the user (driver) to notice that a coolant level reduction abnormality has occurred in the coolant circuit 1.

[0086] Next, when the coolant water reduction anomaly determination unit 44 determines that a coolant water reduction anomaly has occurred in the coolant circuit 1, the output reduction instruction unit 46 instructs the cooled equipment 13 to reduce its output (step S71). As described above, the cooled equipment 13 is, for example, the drive motor 14 and the inverter 15, and reducing the output prevents the cooled equipment 13 from overheating.

[0087] According to the coolant reduction abnormality detection device 4 for the coolant circuit 1 of the embodiment, it is determined whether the rotation speed of the electric water pump 12 is vibrating, and if it is determined that the rotation speed of the electric water pump 12 is vibrating, it is determined that a reduction in the coolant level has occurred in the coolant circuit 1 into which coolant is poured, and it is possible to detect that a reduction in the coolant level has occurred in the coolant circuit 1.

[0088] In addition, the coolant reduction abnormality determination unit 44 determines that an abnormality such as a continuous reduction in the coolant level has occurred in the coolant circuit 1, thereby making it possible to detect that a coolant reduction abnormality has occurred in the coolant circuit 1 into which coolant is being poured.

[0089] Furthermore, when determining vibration of the EWP rotation speed, it is better to use multiple sets of unit times rather than one set of unit times for the determination. For example, if there are two sets of unit times, a first set of unit times and a second set of unit times can be set, and these sets of unit times can be switched at a predetermined timing. In this way, it is possible to determine more efficiently and with less erroneous detection whether a continuous decrease in the coolant level in the coolant circuit 1 is occurring, which would cause the rotation speed of the electric water pump 12 to vibrate.

[0090] Furthermore, when the coolant low level abnormality determination unit 44 determines that an abnormality has occurred in the coolant circuit 1, such as a continuing coolant low level, which can be said to be caused by the rotation speed of the electric water pump 12 fluctuating, the warning light illumination instruction unit 45 instructs the warning light provided on the instrument panel to illuminate, thereby illuminating the warning light, so that the user (driver) can become aware that a coolant low level abnormality has occurred in the coolant circuit 1.

[0091] Furthermore, when the coolant reduction abnormality determination unit 44 determines that an abnormality has occurred in the coolant circuit 1, such as a continuing reduction in the coolant, which can be said to be the oscillation of the rotation speed of the electric water pump 12, the output reduction instruction unit 46 instructs the cooled target equipment 13 to reduce its output, thereby reducing the output of the cooled target equipment 13 and preventing overheating of the cooled target equipment 13.

[0092] The present invention is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications. [Explanation of symbols]

[0093] 1 Cooling water circuit 11 Capacitor tank 111 Cap 112 Water supply pipe 113 Recovery pipe 114 Water meter 12 Electric water pump 122 Discharge pipe 123 EWPDuty drive unit 13 Equipment to be cooled 14 Drive motor 141 Motor housing 142 Waterways 143 Piping 144 stator coil 145 Motor rotation angle measurement unit 146 Temperature sensor (first temperature sensor) 15 Inverter 151 Motor rotation speed calculation unit 152 Motor drive torque calculation unit 153 Motor current-carrying part 154 Cooling water required flow rate calculation section 155 Temperature sensor (second temperature sensor) 16 Radiator 17 Radiator fan 2. Drive control device 21 EWP drive duty calculation unit 22 EWP drive duty indicator 3 ECU 31 Accelerator pedal 32 Accelerator position sensor (APS) 33 Motor drive torque indicator 34 Water temperature sensor 4. Cooling water reduction abnormality detection device 41 Electric water pump rotation speed measurement unit (EWP rotation speed measurement unit) 42 Flag setting section 421 Maximum value memory section (memory MAX) 422 Minimum value memory section (memory MIN) 423 Dichotomous Value Memory Unit (Memory MID) 43 EWP rotational speed vibration determination unit 44 Cooling water reduction abnormality determination section 45 Warning light indicator 46 Output suppression instruction section 5. Instrument panel 51 Warning light N Electric water pump rotation speed Nmax EWP rotation speed stored in memory MAX Nmin EWP rotation speed stored in memory MIN Nmid The number of revolutions obtained by dividing the sum of Nmax and Nmid stored in memory MID by two CSA Number of flags raised within a unit of time Number of flags raised in a time period longer than the CSB unit time Vp CSB / CSA (ratio of number of flags)

Claims

1. a condenser tank for storing cooling water; an electric water pump connected to the capacitor tank and disposed below the capacitor tank in the direction of gravity; an electric water pump discharge path connected to the electric water pump and extending toward an area above the electric water pump in the direction of gravity; a cooling target device connected to a discharge path of the electric water pump; Equipped with a cooling water circuit coolant low level anomaly detection device that determines an anomaly by detecting whether the rotational speed of the electric water pump vibrates and the vibration continues when the amount of cooling water injected into the cooling water circuit through which the cooling water circulates in the order of the condenser tank, the electric water pump, the electric water pump discharge path, and the cooled equipment becomes low, an electric water pump rotation speed measurement unit that measures the rotation speed of the electric water pump; a maximum value storage unit that updates and stores the rotation speed measured by the electric water pump rotation speed measurement unit as a maximum value when the rotation speed measured by the electric water pump rotation speed measurement unit is increasing, and continues to store the immediately preceding maximum value when the rotation speed measured by the electric water pump rotation speed measurement unit is decreasing; a minimum value storage unit that updates and stores the rotation speed measured by the electric water pump rotation speed measurement unit as a minimum value when the rotation speed measured by the electric water pump rotation speed measurement unit is decreasing, and continues to store the immediately preceding minimum value when the rotation speed measured by the electric water pump rotation speed measurement unit is increasing; a flag setting unit that, when the rotation speed of the electric water pump fluctuates so as to repeatedly have maximum and minimum points, compares the rotation speed obtained by dividing the sum of the maximum value stored in the maximum value storage unit and the minimum value stored in the minimum value storage unit by two with the rotation speed of the electric water pump, and sets a flag each time the rotation speed exceeds the sum or sets a flag each time the rotation speed falls below the sum; an EWP rotational speed vibration determination unit that determines that the rotational speed of the electric water pump is vibrating when a ratio of the number of flags set within a predetermined unit time to the number of flags set within a time longer than the unit time is within a predetermined range; A cooling water circuit abnormality detection device for detecting a decrease in cooling water level.

2. 2. The cooling water circuit according to claim 1, further comprising a cooling water reduction abnormality determination unit that determines that a cooling water reduction abnormality has occurred in the cooling water circuit when the number of times that the rotation speed of the electric water pump is determined to be vibrating continuously reaches a predetermined number of times.

3. 3. The cooling water circuit cooling water reduction abnormality detection device according to claim 1, wherein the unit time is a first unit time and a second unit time different from the first unit time, and the first unit time and the second unit time are switched at a predetermined timing.

4. 3. The cooling water circuit according to claim 2, further comprising a warning light illumination instruction unit that instructs a warning light provided on an instrument panel to illuminate when the cooling water level reduction abnormality determination unit determines that the cooling water level reduction abnormality has occurred for more than a predetermined time.

5. 3. The cooling water reduction abnormality detection device for a cooling water circuit as described in claim 2, further comprising an output suppression instruction unit that instructs the cooled equipment to suppress output when the cooling water reduction abnormality determination unit determines that the cooling water reduction abnormality has occurred for more than a predetermined time.

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