Fault detection device

Abstract

A fault detection device (100) is provided with: a first actuator (10) and a second actuator (20) each driven by electric energy, the second actuator (20) comprising a brush DC motor; a current detection circuit (50) including a first current detection circuit (51) provided to detect a current flowing through the first actuator (10) and a second current detection circuit (52) provided to detect a current generated by arc discharge of the second actuator (20); and a failure determination unit (47) that determines whether there is a failure in each of the first actuator (10) and the second actuator (20) on the basis of the current detected by the current detection circuit (50). The current detection circuit (50) has a current detector (46) that is provided in a common section (53) of the first current detection circuit (51) and the second current detection circuit (52) and that detects a current flowing through the common section (53).

Description

Technical Field

[0001] The invention relates to a fault detection device for detecting a fault of an actuator. Background Art

[0002] As such a technology, there is a device for detecting a disconnection fault in an electromagnetic actuator drive circuit. Such a device is described, for example, in Patent Document 1. In the device described in Patent Document 1, a terminal voltage of a resistor downstream of a solenoid in a weak current circuit is compared with a predetermined reference voltage, thereby detecting whether the weak current circuit has a disconnection.

[0003] However, if a fault detection mechanism is provided for each actuator as in the device described in Patent Document 1, the number of components increases, leading to an increase in cost.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 9-242589 (JPH09-242589A). Summary of the invention

[0007] A fault detection device according to a technical solution of the present invention comprises: a first actuator and a second actuator, each of which is driven by electric energy, wherein the second actuator is composed of a brushed DC motor; a current detection circuit, which includes a first current detection circuit configured to detect a current flowing through the first actuator and a second current detection circuit configured to detect a current generated by arc discharge of the second actuator; and a fault determination unit, which determines whether each of the first actuator and the second actuator has a fault based on the current detected by the current detection circuit. The current detection circuit has a current detector, which is provided in a common portion of the first current detection circuit and the second current detection circuit, and detects the current flowing through the common portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The objects, features and advantages of the present invention will be further clarified through the following description of the embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 This is a circuit diagram schematically showing an example of the overall configuration of a fault detection device according to an embodiment of the present invention.

[0010] Figure 2 This is a circuit diagram schematically showing an example of the overall configuration of a fault detection device as a comparative example of the present invention.

[0011] Figure 3 It is schematically shown Figure 1 A diagram showing an example of the internal structure of a motor.

[0012] Figure 4 It is a block diagram showing a main part configuration of a fault detection device according to an embodiment of the present invention.

[0013] Figure 5 This is a flowchart showing an example of a solenoid failure determination process executed by the failure detection device according to the embodiment of the present invention.

[0014] Figure 6 This is a flowchart showing an example of a motor failure determination process executed by the failure detection device according to the embodiment of the present invention.

[0015] Figure 7 It is shown Figure 1 A table showing an example of the range of currents detected by current detectors when solenoids and motors are operating. DETAILED DESCRIPTION

[0016] Below, refer to Figure 1 to Figure 7 An embodiment of the present invention will be described. A fault detection device according to an embodiment of the present invention detects a fault in an actuator driven by electric energy.

[0017] In recent years, we have been conducting research and development on improving fuel efficiency to contribute to energy efficiency in order to ensure that everyone has access to appropriate, reliable, sustainable and modern energy. For example, we have been conducting research and development on vehicle systems that improve fuel efficiency by switching between two-wheel drive and four-wheel drive.

[0018] Such a vehicle system, for example, includes a hydraulic clutch for switching between a two-wheel drive mode and a four-wheel drive mode, an oil pump for supplying working oil to the hydraulic clutch, and a solenoid valve for opening and closing the oil path from the oil pump to the hydraulic clutch. In such a vehicle system, it is preferable to effectively detect failures of multiple actuators such as a motor driving the oil pump and a solenoid valve. In this embodiment, the fault detection device is configured as follows so that by effectively detecting failures of multiple actuators, an increase in the number of components and an increase in cost can be suppressed.

[0019] Figure 1 1 is a circuit diagram schematically showing an example of the overall configuration of a fault detection device (hereinafter referred to as a device) 100 according to an embodiment of the present invention. Figure 2 1 is a circuit diagram schematically showing an example of the overall configuration of a device 100A as a comparative example of the present invention. Figure 1 and Figure 2A circuit for disconnecting / engaging a hydraulic clutch (not shown) mounted on a vehicle and configured to switch the vehicle's driving mode between a two-wheel drive mode and a four-wheel drive mode is shown. Such a hydraulic clutch is interposed on a driving force transmission path from a driving source such as an engine or a motor to auxiliary driving wheels (e.g., rear wheels), and is interposed on the driving force transmission path in such a manner that the vehicle's driving mode is switched between a two-wheel drive mode and a four-wheel drive mode by disconnecting / engaging the driving force transmission path.

[0020] like Figure 1 and Figure 2 As shown, the device 100, 100A comprises: a solenoid valve 10, which serves as a first actuator driven by electric energy; a motor 20, which serves as a second actuator composed of a brushed DC motor; a DC power supply 30 such as a vehicle battery, which supplies power to the solenoid valve 10 and the motor 20; and an electronic control unit (ECU) 40, 40A, which is clamped between the solenoid valve 10 and the motor 20 and the DC power supply 30.

[0021] The motor 20 is connected to an oil pump that supplies working oil to the hydraulic clutch, and when driven (energized, turned on), the oil pump is driven. The solenoid valve 10 is clamped on the oil path from the oil pump to the hydraulic clutch, and when excited (energized, turned on), the oil path is opened, and when demagnetized (non-energized, turned off), the oil path is closed.

[0022] ECU40 is composed of a computer including a signal generator 41 as a peripheral circuit, switch elements (hereinafter referred to as FET) 42, 43 such as MOSFET (metal oxide semiconductor field effect transistor), current detectors 44 to 46, etc., in addition to I / O (input / output), CPU (central processing unit), ROM (read only memory), and RAM (random access memory). Signal generator 41 is configured as an appropriate signal generating circuit to generate a switch signal that turns on and off the solenoid valve 10 and the motor 20, respectively. Current detectors 44 to 46 are configured as appropriate current detection circuits. FET42 is mounted in the circuit from the DC power supply 30 to the solenoid valve 10. FET43 is mounted in the circuit from the DC power supply 30 to the motor 20.

[0023] When the switching signal from the signal generator 41 is input to the gate of the FET 43, when the FET 43 is turned on, the current flows from the drain to the source of the FET 43, and the power is supplied from the DC power supply 30 to the motor 20. In this case, the motor 20 is turned on, the oil pump is driven, and the pressure oil is supplied to the oil circuit from the oil pump to the hydraulic clutch. In addition, when the switching signal from the signal generator 41 is input to the gate of the FET 42, when the FET 42 is turned on, the current flows from the drain to the source of the FET 42, and the power is supplied from the DC power supply 30 to the solenoid valve 10. In this case, the solenoid valve 10 is turned on, the oil circuit supplied with the pressure oil is opened, and the pressure oil is supplied to the hydraulic clutch. As a result, the driving force transmission path from the driving source to the auxiliary driving wheel is connected, and the driving mode of the vehicle is switched from the two-wheel drive mode to the four-wheel drive mode.

[0024] On the other hand, when the switching signal from the signal generator 41 is input to the gate of the FET 43 and the FET 43 is turned off, the current flowing from the drain of the FET 43 to the source is cut off, and the power supply from the DC power supply 30 to the motor 20 is cut off. In this case, the motor 20 is turned off, the drive to the oil pump is stopped, and the supply of pressure oil to the oil circuit from the oil pump to the hydraulic clutch is cut off. In addition, when the switching signal from the signal generator 41 is input to the gate of the FET 42 and the FET 42 is turned off, the current flowing from the drain of the FET 42 to the source is cut off, and the power supply from the DC power supply 30 to the solenoid valve 10 is cut off. In this case, the solenoid valve 10 is turned off, the oil circuit is closed, and the supply of pressure oil to the hydraulic clutch is cut off. As a result, the driving force transmission path from the driving source to the auxiliary drive wheel is cut off, and the driving mode of the vehicle is switched from the four-wheel drive mode to the two-wheel drive mode.

[0025] like Figure 2 As shown, the current detector 44 is provided in a circuit through which a current having the same magnitude as the current flowing through the solenoid valve 10 flows, for example, upstream of the FET 42 in the circuit from the DC power supply 30 to the solenoid valve 10, and detects the magnitude of the current flowing through the solenoid valve 10. The ECU 40 (CPU) can determine whether the solenoid valve 10 has a fault based on the switch signal output by the signal generator 41 and the magnitude of the current detected by the current detector 44.

[0026] That is, when the signal generator 41 outputs a switch signal to turn on the solenoid valve 10 (FET 42 is turned on), if it is determined that the solenoid valve 10 is working, it is determined to be in a normal state, and if it is determined that the solenoid valve 10 is not working, it is determined to be in a fault state (solenoid valve disconnection fault). Similarly, when the signal generator 41 outputs a switch signal to turn off the solenoid valve 10 (FET 42 is turned off), if it is determined that the solenoid valve 10 is not working, it is determined to be in a normal state, and if it is determined that the solenoid valve 10 is working, it is determined to be in a fault state (solenoid valve conduction fault).

[0027] If the magnitude of the current detected by the current detector 44 is greater than a predetermined value (e.g., 1.0 A), the solenoid valve 10 is determined to be operating, and if it is less than the predetermined value, the solenoid valve 10 is determined to be not operating. Such a predetermined value is predetermined based on the power supply voltage and the specifications of the solenoid valve 10, and is stored in the ECU 40 (ROM) in advance.

[0028] The current detector 45 is provided in a circuit through which a current having the same magnitude as the current flowing through the motor 20 flows, for example, a circuit from the motor 20 to the chassis ground, and detects the magnitude of the current flowing through the motor 20. The ECU 40 (CPU) can determine whether the motor 20 has a fault based on the switch signal output by the signal generator 41 and the magnitude of the current detected by the current detector 45.

[0029] That is, when the signal generator 41 outputs a switch signal to turn on the motor 20 (FET43 is turned on), if it is determined that the motor 20 is working, it is determined to be in a normal state, and if it is determined that the motor 20 is not working, it is determined to be in a fault state (motor disconnection fault). Similarly, when the signal generator 41 outputs a switch signal to turn off the motor 20 (FET43 is turned off), if it is determined that the motor 20 is not working, it is determined to be in a normal state, and if it is determined that the motor 20 is working, it is determined to be in a fault state (motor conduction fault).

[0030] If the magnitude of the current detected by the current detector 45 is greater than a predetermined value (e.g., 0.5A to 12A), it is determined that the motor 20 is operating, and if it is less than the predetermined value, it is determined that the motor 20 is not operating. Such a predetermined value is predetermined based on the power supply voltage and the specifications of the motor 20, and is stored in the ECU 40 (ROM) in advance.

[0031] Figure 3 2 is a diagram schematically showing an example of the internal structure of the motor 20. Figure 3 As shown, the motor 20 has: three rotors 22, which are configured to rotate around a rotating shaft 21; a pair of stators 23, 24, which are composed of permanent magnets arranged on both sides of the rotor 22; three commutators 25, which are composed of conductors arranged on the rotating shaft 21; and a pair of brushes (internal electrodes) 26, 27, which are configured to contact the commutator 25.

[0032] Coils are wound around the rotors 22. The commutators 25 are insulated from each other and connected to both ends of the coils of the rotors 22, and rotate together with the rotors 22. When current from the DC power supply 30 flows through the brushes 26 and 27, the current flows to the coils via the commutator 25 in contact with the brushes 26 and 27, and the rotor 22 rotates, thereby rotating the motor 20 (operating).

[0033] Such a motor 20 rotates while the commutator 25 is in contact with the brushes 26 and 27, thereby generating sparks (commutation sparks) at the interface between the commutator 25 and the brushes 26 and 27. When the commutation sparks are generated, arc discharge sometimes occurs between the motor 20 and the circuits around the motor 20, and electrical noise is generated in the circuits around the motor 20. In other words, arc discharge occurs when the voltage applied to the motor 20 (motor voltage) is greater than a specified voltage value (minimum arc voltage value) and the current flowing through the motor 20 (motor current) is greater than a specified value (minimum arc current value). The larger the motor current, the higher the frequency of arc discharge.

[0034] exist Figure 1 and Figure 2 In the example shown, the motor 20 is housed in a metal motor case 28. The downstream end of the solenoid valve 10, that is, the downstream end of the circuit from the DC power supply 30 to the solenoid valve 10, is connected to the motor case 28 and is grounded to the chassis via the motor case 28.

[0035] In this case, when a commutation spark is generated in the motor 20, arc discharge is generated between the motor 20 and the motor housing 28, and electrical noise is generated in the circuit grounded from the motor housing 28 to the chassis. That is, when the motor voltage and the motor current are greater than the minimum arc voltage value and the minimum arc current value when the motor 20 is operating, a commutation spark is generated at a frequency corresponding to the magnitude of the motor current when the motor 20 is operating. The metal motor housing 28 is a conductor as a whole, and is disposed close to the motor 20 in a manner surrounding the motor 20. Therefore, when a commutation spark is generated in the motor 20, an arc discharge is generated between the motor 20 and the motor housing 28.

[0036] like Figure 1 As shown, the current detector 46 is provided in the current detection circuit 50 to detect the magnitude of each current, and the current detection circuit 50 detects the current flowing through the solenoid valve 10 and the current (electrical noise) generated by the arc discharge of the motor 20. The current detection circuit 50 includes: a first current detection circuit 51, which detects the current flowing through the solenoid valve 10; and a second current detection circuit 52, which detects the current generated by the arc discharge of the motor 20.

[0037] The first current detection circuit 51 is a circuit through which a current of the same magnitude as the current flowing through the solenoid valve 10 flows, and is a circuit that is grounded from the DC power supply 30 through the solenoid valve 10 to the chassis. The second current detection circuit 52 is a circuit through which a current generated by arc discharge of the motor 20 flows, and is a circuit that is grounded from the motor housing 28 to the chassis. The current detector 46 is provided in the common portion 53 of the first current detection circuit 51 and the second current detection circuit 52, and detects the current flowing through the common portion 53.

[0038] Figure 4 1 is a block diagram showing the main structure of the device 100. Figure 4 As shown, ECU40 has Figure 1 The present invention also includes a fault determination unit 47 as a functional structure such as a CPU, and a storage unit 48 such as a ROM, in addition to the signal generator 41, the current detector 46, etc.

[0039] The fault determination unit 47 determines whether the solenoid valve 10 has a fault based on the switch signal output by the signal generator 41 and the magnitude I of the current detected by the current detector 46. That is, when the signal generator 41 outputs a switch signal that turns on the solenoid valve 10 (FET42 is turned on), if it is determined that the solenoid valve 10 is working, it is determined to be in a normal state, and if it is determined that the solenoid valve 10 is not working, it is determined to be in a fault state (solenoid valve disconnection fault). Similarly, when the signal generator 41 outputs a switch signal that turns off the solenoid valve 10 (FET42 is turned off), if it is determined that the solenoid valve 10 is not working, it is determined to be in a normal state, and if it is determined that the solenoid valve 10 is working, it is determined to be in a fault state (solenoid valve conduction fault).

[0040] When the solenoid valve 10 is working, a current of a certain magnitude I (e.g., 1.0A) is detected by the current detector 46. When the solenoid valve 10 is not working, a current of a certain magnitude I (0A) cannot be detected. If the magnitude I of the current detected by the current detector 46 is greater than a predetermined value I0 (e.g., 1.0A), the fault determination unit 47 determines that the solenoid valve 10 is working. If it is less than the predetermined value I0, the fault determination unit 47 determines that the solenoid valve 10 is not working. The predetermined value I0 is predetermined based on the power supply voltage and the specifications of the solenoid valve 10, and is stored in the storage unit 48 in advance.

[0041] The current detected by the current detector 46 includes a current of a certain magnitude I flowing through the common portion 53 after passing through the solenoid valve 10 and a peak value (current peak value as electrical noise) of a periodic current generated in the motor housing 28 and flowing through the common portion 53. The fault determination unit 47 can compare the current of a certain magnitude I flowing through the common portion 53 after passing through the solenoid valve 10 with the prescribed value I0, for example, by comparing the minimum value of the magnitude I of the current detected in a prescribed fault determination cycle (e.g., 100 ms) with the prescribed value I0.

[0042] The fault determination unit 47 also determines whether the motor 20 has a fault based on the switch signal output by the signal generator 41 and the occurrence frequency N of the current peak value detected by the current detector 46. That is, when the signal generator 41 outputs a switch signal that turns on the motor 20 (FET43 is turned on), if it is determined that the motor 20 is working, it is determined to be in a normal state, and if it is determined that the motor 20 is not working, it is determined to be in a fault state (motor disconnection fault). Similarly, when the signal generator 41 outputs a switch signal that turns off the motor 20 (FET43 is turned off), if it is determined that the motor 20 is not working, it is determined to be in a normal state, and if it is determined that the motor 20 is working, it is determined to be in a fault state (motor conduction fault).

[0043] The fault determination unit 47 takes the current whose magnitude I is greater than a specified value (e.g., a specified value I0+0.3A) as the current peak value, and counts the current peak value detected by the current detector 46 in a specified fault determination period (e.g., 100ms). When the motor 20 is working, the current detector 46 detects a current peak value with a certain occurrence frequency N (e.g., 60 times / 100ms). When the motor 20 is not working, the current peak value cannot be detected (0 times / 100ms). If the occurrence frequency N of the current peak value is greater than the specified frequency N0 (e.g., 50 times / 100ms), the fault determination unit 47 determines that the motor 20 is working, and if the occurrence frequency N of the current peak value is less than the specified frequency N0, it is determined that the motor 20 is not working.

[0044] The frequency N of the current peak is roughly consistent with the frequency of arc discharge in the motor 20. The larger the motor current is, the higher the frequency N is. More specifically, it is proportional to the motor current. Therefore, the specified frequency N0 is predetermined according to the motor current. The characteristic representing the relationship between the specified frequency N0 and the motor current is predetermined according to the power supply voltage and the specifications of the motor 20, and is pre-stored in the storage unit 48.

[0045] Figure 5 1 is a flowchart showing an example of a solenoid failure determination process executed by the device 100 . Figure 61 is a flowchart showing an example of the motor failure determination process executed by the device 100 . Figure 5 and Figure 6 The process shown in the flowchart is started, for example, when the vehicle is started and the ECU 40 is started, and is repeatedly performed at a predetermined cycle (for example, 100 ms).

[0046] like Figure 5 As shown, in the solenoid fault determination process, first in step S1, it is determined whether the signal generator 41 outputs a switch signal that turns on the electromagnetic valve 10. When step S1 is affirmative (S1: Yes), the process proceeds to step S2 to determine whether the magnitude I (minimum value) of the current detected by the current detector 46 is greater than the specified value I0. When step S2 is affirmative (S2: Yes), it is determined that the electromagnetic valve 10 is working, and the process proceeds to step S3 to determine that the electromagnetic valve 10 has no fault (normal state), and the process ends. On the other hand, when step S2 is negative (S2: No), it is determined that the electromagnetic valve 10 is not working, and the process proceeds to step S4 to determine that the electromagnetic valve 10 has a fault (solenoid valve disconnection fault), and the process ends.

[0047] When step S1 is negative (S1: No), the process proceeds to step S5 to determine whether the magnitude I (minimum value) of the current detected by the current detector 46 is less than the specified value I0. When step S5 is positive (S5: Yes), the process determines that the solenoid valve 10 is not working, and the process proceeds to step S3 to determine that the solenoid valve 10 is not faulty (normal state), and the process ends. On the other hand, when step S5 is negative (S5: No), the process determines that the solenoid valve 10 is working, and the process proceeds to step S6 to determine that the solenoid valve 10 is faulty (solenoid valve conduction fault), and the process ends.

[0048] like Figure 6 As shown, in the motor failure determination process, first in step S10, it is determined whether the signal generator 41 outputs a switch signal to turn on the motor 20. When step S10 is affirmative (S10: Yes), the process proceeds to step S11 to determine whether the occurrence frequency N of the current peak value detected by the current detector 46 is greater than the specified frequency N0. When step S11 is affirmative (S11: Yes), it is determined that the motor 20 is working, and the process proceeds to step S12 to determine that the motor 20 has no fault (normal state), and the process ends. On the other hand, when step S11 is negative (S11: No), it is determined that the motor 20 is not working, and the process proceeds to step S13 to determine that the motor 20 has a fault (motor disconnection fault), and the process ends.

[0049] When step S10 is negative (S10: No), the process proceeds to step S14 to determine whether the occurrence frequency N of the current peak value detected by the current detector 46 is less than the specified frequency N0. When step S14 is positive (S14: Yes), it is determined that the motor 20 is not working, and the process proceeds to step S12 to determine that the motor 20 is not faulty (normal state), and the process ends. On the other hand, when step S14 is negative (S14: No), it is determined that the motor 20 is working, and the process proceeds to step S15 to determine that the motor 20 is faulty (motor conduction fault), and the process ends.

[0050] Figure 7 4 is a diagram for explaining another example of the fault determination process performed by the fault determination unit 47, and is a table showing an example of the range of the magnitude I of the current detected by the current detector 46 when the solenoid valve 10 and the motor 20 are each operating. The fault determination unit 47 may also determine whether the solenoid valve 10 and the motor 20 are each operating by comparing the average value of the magnitude I of the current detected in the fault determination cycle with the predetermined range of the magnitude I of the current.

[0051] That is, when only the solenoid valve 10 is working, the magnitude I (average value) of the current detected by the current detector 46 during the fault judgment period is within a specified first range (for example, 1.0A (1.0A±small current value). When only the motor 20 is working, the greater the frequency N of occurrence of the motor current, arc discharge, and current peak, the greater the magnitude I (average value) of the current detected by the current detector 46 during the fault judgment period, and within a specified second range (for example, 0A to 0.5A). The first range and the second range are predetermined based on the power supply voltage, the specifications of the solenoid valve 10 and the motor 20, etc., and are pre-stored in the storage unit 48.

[0052] like Figure 7 As shown, if the magnitude I (average value) of the current detected by the current detector 46 during the fault determination cycle is within the combined range of the first range and the second range (e.g., 1.0A to 1.5A), the fault determination unit 47 can determine that both the solenoid valve 10 and the motor 20 are working. If the magnitude I (average value) of the detected current is within the first range (e.g., 1.0A), it can be determined that only the solenoid valve 10 is working and the motor 20 is not operating. If the magnitude I (average value) of the detected current is within the second range (e.g., 0A to 0.5A), it can be determined that only the motor 20 is working and the solenoid valve 10 is not working. In addition, if no current (0A) is detected, it can be determined that both the solenoid valve 10 and the motor 20 are not working.

[0053] According to this embodiment, the following effects can be achieved.

[0054] (1) The device 100 comprises: a solenoid valve 10 and a motor 20, each of which is driven by electric energy, wherein the motor 20 is composed of a brushed DC motor; a current detection circuit 50, which includes a first current detection circuit 51 configured to detect the current flowing through the solenoid valve and a current (electrical noise) generated by arc discharge of the motor 20; and a fault determination unit 47, which determines whether the solenoid valve 10 and the motor 20 are faulty (faulty) or not, based on the current detected by the current detection circuit 50. Figure 1 , Figure 4 The current detection circuit 50 includes a current detector 46, which is provided in a common portion 53 of the first current detection circuit 51 and the second current detection circuit 52, and detects the current flowing through the common portion 53 ( Figure 1 ).

[0055] In this way, by providing a single current detector 46 in the common portion 53 through which the current of the same magnitude as the current flowing through the solenoid valve 10 and the current generated by the arc discharge of the motor 20 flow, the number of components required for fault detection of the actuator can be reduced, and the increase in cost can be suppressed. In addition, by distinguishing between the current of a certain magnitude I flowing through the common portion 53 after passing through the solenoid valve 10 and the periodic current peak value flowing through the common portion 53 after being generated in the motor housing 28, and performing fault determination processing, it is possible to efficiently and accurately determine the faults of multiple actuators based on the single detection value of the magnitude I of the current flowing through the common portion 53.

[0056] (2) The fault determination unit 47 determines whether the electromagnetic valve 10 has a fault based on the magnitude I (minimum value) of the current detected by the current detector 46, and determines whether the motor 20 has a fault based on the occurrence frequency N of the current peak value detected by the current detector 46 ( Figure 5 , Figure 6 The fault determination unit 47 determines that the solenoid valve 10 is working when the magnitude I (minimum value) of the current is greater than the specified value I0, and determines that the motor 20 is working when the frequency N of the current peak is greater than the specified frequency N0. Figure 5 , Figure 6 In this case, by using the single detection value of the magnitude I of the current flowing through the common portion 53, it is possible to accurately determine the fault of the solenoid valve 10 based on the magnitude I of the current flowing through the common portion 53 after passing through the solenoid valve 10, and it is possible to accurately determine the fault of the motor 20 based on the occurrence frequency N of the current peak value flowing through the common portion 53 after being generated in the motor housing 28.

[0057] (3) The device 100 further includes a storage unit 48, which stores in advance a first range of a range of the magnitude I (average value) of the current detected by the current detector 46 when the solenoid valve 10 is operating and a second range of a range of the magnitude I (average value) of the current detected by the current detector 46 when the motor 20 is operating. Figure 4 The fault determination unit 47 determines whether the electromagnetic valve 10 and the motor 20 are faulty or not, based on the magnitude I (average value) of the current detected by the current detector 46 and the first range and the second range stored in the storage unit 48 ( Figure 7 In this case, by using the single detection value of the magnitude I of the current flowing through the common portion 53, it is possible to accurately determine the fault of the solenoid valve 10 based on the magnitude I of the current flowing through the common portion 53 after passing through the solenoid valve 10, and it is possible to accurately determine the fault of the motor 20 based on the magnitude I of the current flowing through the common portion 53 after being generated in the motor housing 28.

[0058] In the above embodiment, an example is described in which the device 100 performs fault determination on each of the solenoid valve 10 and the motor 20. However, the first actuator that performs fault determination together with the second actuator formed of a brushed DC motor may be any actuator as long as it is driven by electric energy. The first actuator may be an actuator other than a solenoid valve or may be a motor.

[0059] In the above embodiment, Figure 1 In the examples described above, the motor 20 is housed in a metal motor housing 28, arc discharge occurs between the motor 20 and the motor housing 28, and electrical noise is generated in a circuit grounded from the motor housing 28 to the chassis. That is, the second current detection circuit 52 through which the current generated by the arc discharge of the motor 20 flows is illustrated as a circuit grounded to the chassis via the motor housing 28. However, the second current detection circuit configured to detect the current generated by the arc discharge of the second actuator is not limited to this. For example, a circuit around the motor 20 reached by the arc discharge of the motor 20 housed in the motor housing of a non-conductive member may be used as the second current detection circuit.

[0060] In the above embodiment, referring to Figure 5 to Figure 7 The examples of determining whether the electromagnetic valve 10 and the motor 20 have a conduction fault or a disconnection fault are described above, but it is also possible to determine whether there is an overcurrent fault where the current flowing through the electromagnetic valve 10 and the motor 20 is excessive or an undercurrent fault where the current is insufficient.

[0061] One or more of the above-described embodiments and modifications may be arbitrarily combined, and modifications may be combined with each other.

[0062] According to the present invention, it is possible to suppress an increase in cost.

[0063] The present invention has been described above in conjunction with preferred embodiments, and it should be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the disclosure of the claims set forth below.

Claims

1. A fault detection device, characterized in that: have: A first actuator and a second actuator, each of which is driven by electric energy, wherein the second actuator is composed of a brushed DC motor; a current detection circuit comprising a first current detection circuit configured to detect a current flowing through the first actuator and a second current detection circuit configured to detect a current generated by an arc discharge of the second actuator; as well as a fault determination unit that determines whether each of the first actuator and the second actuator has a fault based on the current detected by the current detection circuit, The current detection circuit includes a current detector provided in a common portion of the first current detection circuit and the second current detection circuit, and detecting a current flowing through the common portion.

2. The fault detection device according to claim 1, characterized in that: The failure determination unit determines whether the first actuator has a failure based on the magnitude of the current detected by the current detector, and determines whether the second actuator has a failure based on the frequency of occurrence of a peak value of the current detected by the current detector.

3. The fault detection device according to claim 2, characterized in that: The failure determination unit determines that the first actuator is operating when the magnitude of the current is equal to or greater than a predetermined value, and determines that the second actuator is operating when the frequency of occurrence of the peak value of the current is equal to or greater than a predetermined frequency.

4. The fault detection device according to claim 1, characterized in that: further comprising a storage unit that stores in advance a first range of a current magnitude detected by the current detector when the first actuator is operating and a second range of a current magnitude detected by the current detector when the second actuator is operating, The failure determination unit determines whether or not each of the first actuator and the second actuator has a failure based on the magnitude of the current detected by the current detector and the first range and the second range stored in the storage unit.

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