Determination Device, Determination Method, and Program

Abstract

To determine whether a switch that switches on and off in response to temperature changes is stuck on.SOLUTION: In a heating circuit in which a heat generating portion and a first switch that switches on and off in response to temperature changes are connected in series to a power source, when the integrated value of the power generated by the heat generating portion is greater than or equal to a predetermined threshold value, it is determined that the first switch is stuck on.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a determination device, a determination method, and a program.

Background Art

[0002] An electric coolant heater used in an electric vehicle or a hybrid car is provided with a switch to prevent overheating. As a switch to prevent overheating, there is a switch that prevents overheating by making another IGBT switch off and cutting off the current when one IGBT is stuck on by redundant IGBTs (Insulated Gate Bipolar Transistors). Also, a switch including a switch such as a bimetal switch that switches on and off according to temperature change may be used. A switch such as a bimetal switch is a switch that turns off when the temperature exceeds a predetermined temperature (Patent Document 1). This switch prevents overheating by switching off a switch such as a bimetal switch when heated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above switch, when a switch that switches on and off according to temperature change malfunctions such as being stuck on, it may not be possible to prevent overheating. The present invention has been made in consideration of such circumstances, and one of its purposes is to determine that a switch that switches on and off according to temperature change is stuck on.

Means for Solving the Problems

[0005] The determination device, determination method, and program according to the present invention employ the following configurations. (1): In a heating circuit in which a first switch that switches on and off in response to a temperature change of a heating unit is connected in series to a power supply, when the integrated value of the power generated by the heating unit is equal to or greater than a predetermined threshold value, it is determined that the first switch is stuck on.

[0006] (2): In the aspect of (1) above, the heating circuit further includes a second switch connected in series to the heating unit and the first switch, and the determination device determines that the first switch is stuck on when the integrated value of the power generated by the heating unit is equal to or greater than the predetermined threshold value after it is determined that the second switch is stuck on.

[0007] (3): In the aspect of (2) above, the determination device further includes a contact switching unit that cuts off the power supplied from the power supply to the heating circuit when it is determined that the second switch is stuck on and it is determined that the first switch is stuck on.

[0008] (4): In the aspect of (1) or (2) above, the predetermined threshold value is a value greater than the integrated value of the power value when the normal first switch turns off.

[0009] (5): In the aspect of (1) or (2) above, the predetermined threshold value is a value smaller than the integrated value of the power value when the cover covering the heating circuit melts.

[0010] (6): In the aspect of (1) or (2) above, the predetermined threshold value is determined based on the temperature of the heating circuit before heating.

[0011] (7): The determination method according to one aspect of the present invention determines that the first switch is stuck on when the integrated value of the power generated by the heating unit is equal to or greater than a predetermined threshold value in a heating circuit in which the heating unit and the first switch are connected in series to a power supply.

[0012] (8): A program for causing a computer to execute the determination method of (7).

Advantages of the Invention

[0013] (1), According to the aspects of (7) and (8), since the first switch has not been switched off, the integrated value of the power generated by the heating unit is equal to or greater than a predetermined threshold value, and it can be determined that the first switch is stuck on.

[0014] (2) According to the aspect, after it is determined that the second switch is stuck on, when the integrated value of the power generated by the heating unit is equal to or greater than the predetermined threshold value, by determining whether the first switch is stuck on, it is possible to prevent determining that the heating circuit is faulty when the second switch is normal.

[0015] (3) According to the aspect, by cutting off the power supplied to the heating circuit by the contact switching unit, it is possible to prevent the heating circuit from overheating.

[0016] (4) According to the aspect, by setting the predetermined threshold value to a value larger than the integrated value of the power values when the normal first switch is turned off, it is possible to prevent determining that the heating circuit is faulty when the first switch is normal.

[0017] (5) According to the aspect, by setting the predetermined threshold value to a value smaller than the integrated value of the power values when the cover covering the heating circuit melts, it is possible to prevent smoking and ignition of the heating circuit.

[0018] (6) According to the aspect, by determining the predetermined threshold value based on the temperature of the heating circuit before heating, it is possible to compensate for changes in the degree of heating due to temperature differences.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0020] <First Embodiment> Hereinafter, embodiments of the determination device of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of the heating system 1 according to the first embodiment. The heating system 1 according to the first embodiment includes a heating circuit 10, a power source 20, and a determination device 30. The heating circuit 10 includes a bimetal switch 11, a voltage detection circuit 12, a heating unit 13, and a current detection circuit 14.

[0021] When current flows through the heating circuit 10, heat is generated. The heating circuit 10 is, for example, a fluid heater used in an electric vehicle or the like. The bimetal switch 11, which is an example of a first switch, is a switch that switches from on to off when the temperature rises by utilizing the fact that the bimetal bends in response to a temperature change. This bimetal switch 11 is installed at a position where it can bend in response to a temperature change of the fluid of the fluid heater or the heating part 13 described later. The voltage detection circuit 12 measures the voltage applied to the heating part 13. The heating part 13 converts electrical energy into thermal energy and generates heat. The heating part 13 is, for example, a heating wire. The current detection circuit 14 measures the current flowing through the heating part 13. The voltage detection circuit 12 and the current detection circuit 14 can detect the power of the heating part 13 by detecting the voltage and the current respectively. The power supply 20 supplies power to the heating circuit 10.

[0022] When the temperature rises, the bimetal switch 11 switches from on to off, thereby cutting off the power supplied to the heating part 13 when the heating part 13 becomes hot. If the bimetal switch 11 becomes stuck in the on state due to a failure or the like, the power supplied to the heating part 13 cannot be cut off when the heating part 13 becomes hot. The bimetal switch 11 is used as a switch that turns on and off for temperature control of the heating part 13.

[0023] The determination device 30 determines whether or not the bimetal switch 11 is stuck in the on state based on the integrated value of the energy generated by the heating part 13. The determination device 30 includes a voltage value acquisition part 31, a current value acquisition part 32, a power value calculation part 33, a power integrated value calculation part 34, a bimetal switch on-stuck determination part 35, and a determination result output part 36.

[0024] The voltage value acquisition unit 31 acquires the voltage value detected by the voltage detection circuit 12. The current value acquisition unit 32 acquires the current value detected by the current detection circuit 14. The power value calculation unit 33 calculates the power value from the acquired current value and voltage value. The power value calculation unit 33 calculates the power value, for example, at regular intervals. The power integrated value calculation unit 34 calculates the integrated value of the calculated power values. The power integrated value calculation unit 34 calculates the power integrated value, for example, by adding the power value calculated by the power value calculation unit 33 to the previously calculated power integrated value.

[0025] The power integrated value calculation unit 34 may reset the power integrated value to 0 at predetermined time intervals. Also, when the voltage value detected by the voltage detection circuit 12 is 0, the power integrated value calculation unit 34 may reset the power integrated value to 0. The fact that the voltage value detected by the voltage detection circuit 12 is 0 indicates that the bimetal switch 11 is open and off. The power integrated value calculation unit 34 may decrease the power integrated value when the heating unit 13 is off, that is, when the power supplied to the heating unit 13 is 0.

[0026] The bimetal switch on-stuck determination unit 35 determines whether the bimetal switch 11 is stuck on based on the integrated value of the calculated power values. The bimetal switch on-stuck determination unit 35 determines that the bimetal switch 11 is stuck on when the integrated value of the calculated power values is equal to or greater than a predetermined threshold value. The threshold value is set, for example, to a value greater than the integrated value of the power values when the normal bimetal switch 11 turns off and less than the integrated value of the power values when the cover covering the heating circuit 10 melts. Also, the threshold value may be determined based on the temperature of the heating circuit 10 before heating.

[0027] The determination result output unit 36 outputs the determination result by the bimetal switch on-stuck determination unit 35. Based on the determination result, it is possible to determine whether the bimetal switch 11 is stuck on. When the set value is greater than the integrated value of the power value when the bimetal switch 11 with a normal threshold turns off and less than the integrated value of the power value when the cover covering the heating circuit 10 melts, when the bimetal switch 11 is normal, before the integrated value of the power value reaches the threshold, the bimetal switch 11 switches off, so the integrated value of the power value becomes less than or equal to the threshold, and the bimetal switch on sticking determination unit 35 determines that the bimetal switch 11 is not stuck on. When the bimetal switch 11 is stuck on, when the integrated value of the power value reaches the threshold, the bimetal switch on sticking determination unit 35 determines that the bimetal switch 11 is stuck on, and the determination result output unit 36 outputs the determination result. Based on the determination result, measures such as replacing the heating circuit 10 can be taken.

[0028] The heating part 13 may include a temperature sensor. The temperature sensor included in the heating part 13 can, for example, detect the temperature of the hot water heated by the heating part 13 and have a temperature adjustment function in the heating part 13 so that the temperature becomes the set temperature. When the heating part 13 has a temperature adjustment function, the power integrated value calculation unit 34 may start calculating the power integrated value after an abnormality (such as duty abnormality) in the heating part 13 is detected.

[0029] Figure 2 is a flowchart showing the operation of the determination device 30 according to the first embodiment. The power integrated value calculation unit 34 calculates the power integrated value (step S101). Thereafter, the bimetal switch on sticking determination unit 35 determines whether the bimetal switch 11 is stuck based on the power integrated value (step S102). The determination result output unit 36 outputs the determination result.

[0030] <Second Embodiment> FIG. 3 is a diagram showing an example of the configuration of the heating system 1 according to the second embodiment. The heating system 1 according to the second embodiment includes a heating circuit 10, a power supply 20, and a determination device 30, similar to the heating system 1 according to the first embodiment. The heating circuit 10 according to the second embodiment includes a second switch 15 in addition to the heating circuit 10 according to the first embodiment. The determination device 30 according to the second embodiment includes a second switch switching unit 37 and a second switch on-fixing determination unit 38 in addition to the determination device 30 according to the first embodiment. Note that the bimetal switch 11 in the heating system 1 according to the second embodiment may be a type of switch that can repeat on and off according to temperature, similar to the bimetal switch 11 of the heating system 1 according to the first embodiment, or may be a type of switch that changes unidirectionally from on to off as the temperature increases.

[0031] The second switch 15 controls the current flowing through the heating unit 13 by switching on and off. The second switch 15 is a semiconductor switch such as an IGBT, for example.

[0032] The second switch switching unit 37 controls the current flowing through the heating unit 13 and switches the presence or absence of heat generation by switching the on and off of the second switch 15. The second switch on-fixing determination unit 38 determines whether or not the second switch 15 is fixed in the on state. The second switch on-fixing determination unit 38 determines whether or not the second switch 15 is fixed in the on state by detecting the difference (for example, Duty difference) between the maximum output set by control (for example, Duty control) and the output by the heating unit 13, for example. The second switch on-fixing determination unit 38 may periodically determine whether or not the second switch 15 is fixed in the on state, or may determine whether or not the second switch 15 is fixed in the on state according to the input to the determination device 30.

[0033] The power integration value calculation unit 34 according to the second embodiment calculates the integrated value of the power values calculated after it is determined by the second switch on-stuck determination unit 38 that the second switch 15 is on-stuck. When the second switch 15 is normal and the bimetal switch 11 is on-stuck, the heating circuit 10 operates normally. By calculating the integrated value of the power values after it is determined by the second switch on-stuck determination unit 38 that the second switch 15 is on-stuck, the power integration value calculation unit 34 can determine that the bimetal switch 11 is on-stuck when the second switch 15 is normal, and can prevent the heating circuit 10 from being replaced.

[0034] Figure 4 is a flowchart showing the operation of the determination device 30 according to the second embodiment. The second switch on-stuck determination unit 38 determines whether the second switch is on-stuck (step S111). When it is determined that the second switch is on-stuck, the power integration value calculation unit 34 starts calculating the integrated value of the power values (step S112) and calculates the integrated value of the power values (step S113). When it is determined that the second switch is not on-stuck, no particular operation is performed, and for example, step S111 is performed again after a predetermined time has elapsed.

[0035] After the integrated value of the power values is calculated, the bimetal switch on-stuck determination unit 35 determines whether the integrated value is equal to or greater than a predetermined threshold (step S114). When it is determined that the integrated value is equal to or greater than the predetermined threshold, the bimetal switch on-stuck determination unit 35 determines that the bimetal switch 11 is on-stuck (step S115), and the determination result output unit 36 outputs the determination result (step S116). In response to the determination result, measures such as replacing the heating circuit 10 can be taken.

[0036] When it is not determined that the integrated value is equal to or greater than a predetermined threshold, the power integrated value calculation unit 34, for example, performs the operation of step S113 again after a predetermined time has elapsed to calculate the integrated value of the power value. When it is determined in step S114 that the integrated value of the power value is less than the predetermined threshold for a predetermined number of times or more, the bimetal switch on-stuck determination unit 35 may determine that the bimetal switch 11 is not stuck. This is because when it is determined that the integrated value of the power value is less than the predetermined threshold for a predetermined number of times or more, the bimetal switch 11 has already turned off, and the integrated value of the power value may not increase. When the integrated value of the power value is the same for a predetermined number of times or more, the bimetal switch on-stuck determination unit 35 may determine that the bimetal switch 11 is not stuck.

[0037] <Third Embodiment> FIG. 5 is a diagram showing an example of the configuration of the heating system 1 according to the third embodiment. The heating system 1 according to the third embodiment includes a heat generation circuit 10, a power supply 20, and a determination device 30, similar to the heating system 1 according to the second embodiment. The heating system 1 according to the third embodiment includes a contact 40 between the heat generation circuit 10 and the power supply 20. The determination device 30 according to the third embodiment includes a contact switching unit 39 in addition to the determination device 30 according to the second embodiment.

[0038] The contact 40 switches between on and off to switch whether the power supply 20 supplies power to the heat generation circuit 10. The contact switching unit 39 switches the on / off state of the contact 40 based on the determination by the bimetal switch on-stuck determination unit 35 and the determination by the second switch on-stuck determination unit 38. When the second switch on-stuck determination unit 38 determines that the second switch 15 is on-stuck and the bimetal switch on-stuck determination unit 35 determines that the bimetal switch 11 is on-stuck, the contact switching unit 39 switches the contact 40 to off.

[0039] FIG. 6 is a flowchart showing the operation of the determination device 30 according to the third embodiment. The operations from step S121 to step S125 are the same as the operations from step S111 to step S11 in the second embodiment. When the contact switching unit 39 determines that the bimetal switch 11 is on and fixed, it switches the contact 40 to off.

[0040] FIG. 7 is a diagram showing the states of the second switch 15, the bimetal switch 11, and the on / off switching of the contact 40 in the third embodiment. Hereinafter, the threshold value serving as the determination criterion by the bimetal switch on-fixation determination unit 35 is a value larger than the integrated value of the power values when the normal bimetal switch 11 turns off. In case #1, the second switch 15 is on and fixed, and the bimetal switch 11 is normal. In case #1, since the bimetal switch 11 is normal, the current supply to the heating unit 13 can be interrupted by the bimetal switch 11 switching to off due to the heat generated by the heating unit 13. Therefore, it is not necessary to switch the contact 40 to off.

[0041] In case #2, the second switch 15 is normal, and the bimetal switch 11 is on and fixed. In case #2, since the second switch 15 is normal, it is possible to control the current supply to the heating unit 13. Therefore, it is not necessary to switch the contact 40 to off.

[0042] In case #3, the second switch 15 is on and fixed, and the bimetal switch 11 is also on and fixed. At this time, the bimetal switch 11 cannot be switched to off due to the heat generated by the heating unit 13. Therefore, it is necessary to interrupt the current supply to the heating circuit 10 by switching the contact 40 to off.

[0043] As described above, the determination device 30 can prevent overheating of the heating circuit 10 by the contact switching unit 39 switching the contact 40 to the off state according to the situation. Further, since the threshold value serving as the determination criterion by the bimetal switch on-fixation determination unit 35 is a value larger than the integrated value of the power values when the normal bimetal switch 11 is turned off, it is possible to prevent the contact 40 from turning off when the bimetal switch 11 is normal.

[0044] Also, similar to the first embodiment, in the third embodiment as well, the threshold value serving as the determination criterion by the bimetal switch on-fixation determination unit 35 may be set to a value smaller than the integrated value of the power values when the cover covering the heating circuit 10 melts. At this time, the contact switching unit 39 can switch the contact 40 to the off state before the cover covering the heating circuit 10 melts, and it is possible to prevent smoking or ignition of the heating circuit 10.

[0045] The heating system 1 according to the third embodiment is mounted on, for example, an electric vehicle or a hybrid car.

[0046] The bimetal switch on-fixation determination unit 35 may determine the on-fixation of the bimetal switch 11 based on the internal voltage detected from the heating circuit 10. When the bimetal switch 11 is normally turned off, the internal voltage is 0V. The bimetal switch on-fixation determination unit 35 may determine that the bimetal switch is on-fixed when the internal voltage detected from the heating circuit 10 is equal to or higher than a reference value. The reference value is set in consideration of, for example, variations in the detection of the internal voltage. The bimetal switch on-fixation determination unit 35 may combine the determination method based on the integrated value of the power values in the present embodiment and the determination method based on the internal voltage to determine the on-fixation of the bimetal switch.

[0047] The bimetal switch 11 used to cut off power when the heating part 13 in the heating circuit 10 becomes high temperature may be a switch (first switch) that is not a bimetal switch. For example, the first switch only needs to be able to switch on and off according to temperature changes, and may be, for example, a thermostat.

[0048] The components of the determination device 30 are realized, for example, when a hardware processor such as a CPU (Central Processing Unit) executes a program (software). Some or all of these components may be realized by hardware (including a circuit part; circuitry) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), GPU (Graphics Processing Unit), or may be realized by the cooperation of software and hardware. The program may be stored in advance in a storage device (a storage device having a non-transitory storage medium) such as an HDD (Hard Disk Drive) or a flash memory, or may be stored in a removable storage medium (non-transitory storage medium) such as a DVD or a CD-ROM, and may be installed by mounting the storage medium on a drive device.

[0049] The above-described embodiment can be expressed as follows. A storage device storing a program, A hardware processor, and comprising, By the hardware processor executing the program stored in the storage device, In a heating circuit in which a heating part and a bimetal switch are connected in series to a power supply, when an integrated value of energy generated by the heating part is equal to or greater than a predetermined threshold value, it is determined that the bimetal switch is stuck on. The determination device is configured as described above.

[0050] As described above, the embodiments for carrying out the present invention have been described using embodiments. However, the present invention is not limited to such embodiments at all, and various modifications and substitutions can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0051] 1 Heating system 10 Heating circuit 11 Bimetal switch (first switch) 12 Voltage detection circuit 13 Heating part 14 Current detection circuit 15 Second switch 20 Power supply 30 Determination device 31 Voltage value acquisition part 32 Current value acquisition part 33 Power value calculation part 34 Power integrated value calculation part 35 Bimetal switch on sticking determination part 36 Determination result output part 37 Second switch switching part 38 Second switch on sticking determination part 39 Contact switching part 40 Contact

Claims

1. In a heating circuit in which a heating unit and a first switch that switches on and off in response to temperature changes are connected in series to a power supply, a determination device that determines that the first switch is stuck on when an integrated value of the power generated by the heating unit is equal to or greater than a predetermined threshold, the heating unit has a temperature adjustment function, the integrated value of the power is calculated after an abnormality in the heating unit is detected, Determination device.

2. The heating circuit further includes a second switch connected in series with the heating unit and the first switch, when it is determined that the second switch is stuck on and the integrated value of the power generated by the heating unit is equal to or greater than the predetermined threshold, it is determined that the first switch is stuck on, The determination device according to claim 1.

3. A contact switching unit that cuts off the power supplied from the power supply to the heating circuit when it is determined that the second switch is stuck on and it is determined that the first switch is stuck on, The determination device according to claim 2, further comprising.

4. The predetermined threshold is a value greater than the integrated value of the power values when the normal first switch turns off, The determination device according to claim 1 or 2.

5. The predetermined threshold is a value smaller than the integrated value of the power values when the cover covering the heating circuit melts, The determination device according to claim 1 or 2.

6. The predetermined threshold is determined based on the temperature of the heating circuit before heating, The determination device according to claim 1 or 2.

7. In a heating circuit in which a heating unit and a first switch are connected in series to a power supply, a determination method that determines that the first switch is stuck on when an integrated value of the power generated by the heating unit is equal to or greater than a predetermined threshold, the heating unit has a temperature adjustment function, the integrated value of the power is calculated after an abnormality in the heating unit is detected, Determination method.

8. A program for causing a computer to execute the determination method according to claim 7.

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