Relay diagnostic device for vehicle

Abstract

In the present invention, diagnoses of malfunctions occurring in a plurality of relays is kept from becoming complicated. In the present invention, a relay diagnostic device for a vehicle includes a first detection unit that detects the voltage of a converter, a second detection unit that detects the voltage that is the potential difference between a first power line between the first relay and the converter and a second power line between the second relay and a power storage unit, a third detection unit that detects the voltage between terminals of the first relay, and a control system. The control system executes a step for matching the voltage of the power storage unit and the voltage of the converter, a step for diagnosing that the first relay is abnormally stuck in the OFF state, a step for outputting an ON signal to the second relay, a step for diagnosing that the second relay is abnormally stuck in the OFF state, a step for diagnosing that the second relay is abnormally stuck in the ON state, and a step for diagnosing that the first relay is abnormally stuck in the ON state.

Description

Vehicle relay diagnostic device

[0001] The present disclosure relates to a vehicle relay diagnostic device.

[0002] Diagnosis of whether a relay provided in a vehicle has welded or not has been carried out (see Patent Documents 1, 2, and 3). Also, a vehicle that does not have a precharge circuit for preventing relay welding has been proposed (see Patent Documents 1 and 2).

[0003] Japanese Patent Application Publication No. 2020-099129 Japanese Patent Application Publication No. 2007-295699 Japanese Patent Application Publication No. 2011-055631

[0004] When diagnosing whether or not a plurality of relays are malfunctioning, the configurations such as those in Patent Documents 1 and 2 require the converter to be turned on and off at least once each in diagnosing one relay. In other words, in order to diagnose whether or not a plurality of relays are malfunctioning, the converter must be turned on and off multiple times, which leaves room for improvement.

[0005] An object of the present invention is to prevent the complicated diagnosis of whether or not a plurality of relays are malfunctioning.

[0006] In one embodiment, a vehicle relay diagnostic device diagnoses operation of a first relay and operation of a second relay in a vehicle in which a power storage unit and a converter are connected via a first power line on which a first relay is provided and a second power line on which a second relay is provided and which has a polarity opposite to that of the first power line. The vehicle relay diagnostic device includes a first detector that detects a voltage of the converter, a second detector that detects a voltage that is a potential difference between the first power line between the first relay and the converter and the second power line between the second relay and the power storage unit, a third detector that detects a voltage across terminals of the first relay, and a control system that includes a processor and a memory and controls the converter, the first relay, and the second relay. The control system includes a step of adjusting the voltage of the converter to the voltage of the power storage unit, a step of outputting an ON signal to the first relay when the converter is in an ON state, a step of diagnosing the first relay as being stuck OFF when both the voltage detected by the second detection unit and the voltage between the terminals detected by the third detection unit cannot be detected, a step of outputting an ON signal to the second relay when the converter and the first relay are in an ON state, and a step of outputting an OFF signal to the converter when the voltage at the first detection unit drops. The method executes the following steps: a step of diagnosing the second relay as having an OFF-stuck abnormality; a step of diagnosing the second relay as having an ON-stuck abnormality if the voltage at the first detection unit does not decrease after an OFF signal is output to the second relay when the converter is OFF and the first relay is ON; and a step of diagnosing the first relay as having an ON-stuck abnormality if the voltage between the terminals of the third detection unit is 0 (V) after an OFF signal is output to the first relay when the converter is OFF and the second relay is OFF.

[0007] In one embodiment of the vehicle relay diagnostic device, the control system executes each step so that the converter is turned on and off once each, thereby preventing the complexity of diagnosing whether or not there is a malfunction in multiple relays.

[0008] 1 is a diagram showing a hybrid vehicle equipped with a relay diagnostic device of a first embodiment; FIG. 2 is a block diagram showing a schematic configuration of a hybrid vehicle equipped with the relay diagnostic device of the first embodiment; FIG. 3 is a block diagram showing an example of the functional configuration of a control system; FIG. 4 is a diagram showing an example of the basic structure of a control unit; FIG. 5 is a graph showing the ON / OFF switching times of a system main relay in a hybrid vehicle of the first embodiment and each voltage detected at each time; FIG. 6 is a flowchart showing the first half of an execution procedure in the relay diagnostic devices of the first and second embodiments; FIG. 7 is a flowchart showing the second half of an execution procedure in the relay diagnostic device of the first and second embodiments; FIG. 8 is a flowchart showing an example of an execution procedure in the relay diagnostic device of the second embodiment; FIG. 9 is a block diagram showing the internal configuration of a hybrid vehicle equipped with a relay diagnostic device of a modified example; FIG. 10 is a graph showing the ON / OFF switching times of a system main relay in a hybrid vehicle of a modified example and each voltage detected at each time.

[0009] Hereinafter, the first embodiment, the second embodiment, and modifications will be described in detail with reference to the drawings. In the following description, identical or substantially identical configurations and elements will be designated by the same reference numerals, and repeated description will be omitted.

[0010] [First Embodiment] Fig. 1 is a diagram showing a hybrid vehicle 10 equipped with a relay diagnostic device 40 according to a first embodiment. The hybrid vehicle 10 is an example of a vehicle. The hybrid vehicle 10 is equipped with a powertrain 16 including an engine 12 and a transmission 14. The powertrain 16 has an output shaft 19. Rear wheels 29 are connected to the output shaft 19 via a propeller shaft 21 and a rear differential 23.

[0011] A front differential 25 is incorporated into the transmission 14. Front wheels 27 are connected to the front differential 25. The hybrid vehicle 10 may be of any of a series type, a parallel type, and a series-parallel type. The powertrain 16 is an all-wheel drive powertrain, but is not limited thereto, and a front-wheel drive or rear-wheel drive power unit may also be used.

[0012] Fig. 2 is a block diagram showing a schematic configuration of the hybrid vehicle 10. Fig. 3 is a block diagram showing an example of the functional configuration of the control system 50. Fig. 4 is a diagram showing the basic structure of each control unit included in the control system 50.

[0013] 2, the hybrid vehicle 10 includes an engine 12, a transmission 14, a traction motor 18, an inverter 24, a main battery 26, a sub-battery 28, a DC-DC converter 32, and a system main relay 34. DC stands for Direct Current. The hybrid vehicle 10 also includes a relay diagnostic device 40.

[0014] The hybrid vehicle 10 can be switched between an HEV (Hybrid Electric Vehicle) driving mode in which the hybrid vehicle 10 runs using the power of the engine 12 and the traction motor 18, and an EV (Electric Vehicle) driving mode in which the hybrid vehicle 10 runs using the power of the traction motor 18 with the engine 12 stopped.

[0015] <Engine> The engine 12 is an internal combustion engine that generates power using gasoline or other fuel. The engine 12 is capable of outputting power for driving front wheels 27 and rear wheels 29 of the hybrid vehicle 10. A crankshaft, which is the output shaft of the engine 12, is connected to the transmission 14 via a torque converter or other device. The power output from the engine 12 is speed-shifted by the transmission 14 and transmitted to the front wheels 27 and rear wheels 29.

[0016] The engine 12 is provided with an ISG (Integrated Starter Generator) 13. The output shaft of the ISG 13 is connected to the crankshaft of the engine 12 via a gear. The power output from the ISG 13 is transmitted to the crankshaft of the engine 12. The ISG 13 is connected to a sub-battery 28, for example. The ISG 13 generates power using power supplied from the sub-battery 28. The ISG 13 can also generate power using the power output from the engine 12. The sub-battery 28 can be charged with the power generated by the ISG 13.

[0017] <Transmission, etc.> The transmission 14 is provided with a traction motor 18 and other components inside. The traction motor 18 is an electric motor. The traction motor 18 is connected to a main battery 26 via an inverter 24. The traction motor 18 is capable of power running and regenerative running, and during regenerative running, it converts kinetic energy into electrical energy and charges the main battery 26 via the inverter 24. The traction motor 18 also generates power using the electric power supplied from the main battery 26 via the inverter 24.

[0018] <Main Battery> The main battery 26 is an example of a power storage unit that stores the power supplied to the traction motor 18. Specifically, the main battery 26 is a battery with a higher voltage (for example, 200 (V)) than the sub-battery 28. The voltage of the main battery 26 is detected by a sensor 26A. For example, the main battery 26 is a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery.

[0019] The main battery 26 is connected to each device in the hybrid vehicle 10 via the DCDC converter 32. This allows the power stored in the main battery 26 to be stepped down by the DCDC converter 32 and supplied to each device in the hybrid vehicle 10. A system main relay 34, which will be described later, is provided between the main battery 26 and the DCDC converter 32.

[0020] <Sub-battery> The sub-battery 28 is connected to the main battery 26 via the DCDC converter 32, the first power line 33, and the second power line 35. The sub-battery 28 is a battery with a lower voltage (12 V, for example) than the main battery 26. The sub-battery 28 is charged with power generated by the ISG 13. The power of the sub-battery 28 is supplied to the DCDC converter 32. For example, a secondary battery such as a lead-acid battery or a lithium-ion battery is used as the sub-battery 28.

[0021] <DC-DC Converter> The DC-DC converter 32 is an example of a converter connected to the main battery 26 via the first power line 33, the second power line 35, and the system main relay 34. The DC-DC converter 32 changes the voltage of the sub-battery 28. Specifically, the DC-DC converter 32 boosts the voltage of the sub-battery 28. The DC-DC converter 32 is capable of outputting a voltage equivalent to the voltage of the main battery 26.

[0022] <<First Power Line>> The first power line 33 includes a wiring 33A and a wiring 33B. The wiring 33A connects the DC-DC converter 32 and a terminal A (described later) of the system main relay 34. The wiring 33B connects a terminal B (described later) of the system main relay 34 and the main battery 26. The first power line 33 corresponds to a positive electrode side wiring. One end of a wiring 41 is connected to the wiring 33A. The other end of the wiring 41 is connected to the inverter 24.

[0023] <<Second Power Line>> The second power line 35 includes a wiring 35A and a wiring 35B. The second power line 35 corresponds to a negative electrode wiring. In other words, the second power line 35 has a polarity different from that of the first power line 33. The wiring 35A connects the DCDC converter 32 to a terminal C (described later) of the system main relay 34. The wiring 35B connects a terminal D (described later) of the system main relay 34 to the main battery 26. One end of a wiring 43 is connected to the wiring 35A. The other end of the wiring 43 is connected to the inverter 24. In this way, in the hybrid vehicle 10, the first power line 33 and the second power line 35 connect the main battery 26 and the DCDC converter 32.

[0024] <System Main Relay> The system main relay 34 can electrically connect and disconnect the main battery 26 and the DC-DC converter 32 on both the positive and negative sides. The system main relay 34 is in an open state (disconnected state) when the hybrid vehicle 10 is stopped. The system main relay 34 is in a closed state (connected state) when the hybrid vehicle 10 is started and running. In the following description, an operation of closing the system main relay 34 is referred to as an ON operation, and an operation of opening the system main relay 34 is referred to as an OFF operation. The system main relay 34 specifically includes a positive side relay 36 and a negative side relay 38. Note that "SMRP" in the drawings is an abbreviation for the positive side relay 36. "SMRN" is an abbreviation for the negative side relay 38.

[0025] <<Positive Side Relay>> The positive side relay 36 is an example of a first relay having a terminal A and a terminal B. The positive side relay 36 is provided on the first power line 33 between the main battery 26 and the DCDC converter 32. The ON and OFF operations of the positive side relay 36 are controlled by a control system 50, which will be described later.

[0026] <<Negative Relay>> The negative relay 38 is an example of a second relay having terminals C and D. The negative relay 38 is provided on the second power line 35 between the main battery 26 and the DCDC converter 32. The ON and OFF operations of the negative relay 38 are controlled by a control system 50, which will be described later.

[0027] <Relay Diagnostic Device> The relay diagnostic device 40 is an example of a vehicle relay diagnostic device. The relay diagnostic device 40 diagnoses the operation of each of the positive side relay 36 and the negative side relay 38 within one trip time TP, which will be described later. Specifically, the relay diagnostic device 40 diagnoses whether or not there is a malfunction in each of the positive side relay 36 and the negative side relay 38. In this embodiment, "malfunction" means "stuck-ON abnormality and stuck-OFF abnormality."

[0028] The "stuck-ON abnormality" means that the positive relay 36 and the negative relay 38 do not turn OFF even when the control system 50 (described later) outputs an OFF signal to the positive relay 36 and the negative relay 38. For example, this can be the case when the positive relay 36 and the negative relay 38 are welded to the terminals.

[0029] The "stuck-off abnormality" means that the positive relay 36 and the negative relay 38 do not turn on even when the control system 50 outputs an ON signal to the positive relay 36 and the negative relay 38. For example, this can be the case when a malfunction such as poor contact occurs in the circuit that operates the positive relay 36 and the negative relay 38.

[0030] The relay diagnostic device 40 includes a first voltage sensor 42, a second voltage sensor 44, a third voltage sensor 46, and a control system 50. The control system 50 also serves as the overall control system for the hybrid vehicle 10.

[0031] <<First Voltage Sensor>> The first voltage sensor 42 is an example of a first detection unit. The first voltage sensor 42 detects the voltage on the main battery 26 side of the DCDC converter 32. Specifically, the first voltage sensor 42 is connected to the wiring 33A and the wiring 35A near the input / output terminals of the DCDC converter 32. Hereinafter, the voltage detected by the first voltage sensor 42 will be referred to as VA.

[0032] <<Second Voltage Sensor>> The second voltage sensor 44 is an example of a second detection unit. The second voltage sensor 44 is connected to the wiring 33A between the positive relay 36 and the DCDC converter 32, and is also connected to the wiring 35B between the negative relay 38 and the main battery 26. In other words, the second voltage sensor 44 detects a voltage that is a potential difference between the first power line 33 between the positive relay 36 and the DCDC converter 32 and the second power line 35 between the negative relay 38 and the main battery 26. Hereinafter, the voltage detected by the second voltage sensor 44 will be referred to as VB.

[0033] <<Third Voltage Sensor>> The third voltage sensor 46 is an example of a third detection unit. The third voltage sensor 46 detects the voltage between the terminals of the positive relay 36. That is, the third voltage sensor 46 detects the voltage between terminals A and B. Hereinafter, the voltage between the terminals detected by the third voltage sensor 46 is referred to as VC.

[0034] <<Control System>> The control system 50 includes a processor 73 and a main memory 74. The main memory 74 is an example of a memory. The control system 50 controls the operations of the DCDC converter 32, the positive side relay 36, and the negative side relay 38. The control system 50 is activated based on the driver's operation of a switch. When the driver presses the switch while depressing the brake pedal, the control system 50 controls the hybrid vehicle 10 to a ready-to-run state (Ready ON).

[0035] On the other hand, when the driver presses the switch while depressing the brake pedal while the hybrid vehicle 10 is controlled to a state in which the hybrid vehicle 10 is ready to run, the control system 50 controls the hybrid vehicle 10 to a stopped state (ReadyOFF).

[0036] 2 and 5, in this embodiment, the period from when the DC-DC converter 32 is turned on until the diagnosis by the relay diagnostic device 40 is completed is referred to as "one trip." In this embodiment, the time TP from time t1 to time t9 corresponds to the time required for one trip. Within one trip, the DC-DC converter 32 is turned on once and turned off once. Note that DCDCON and DCDCOFF in the figures represent the ON and OFF states of the DC-DC converter 32.

[0037] The time when the diagnosis by the relay diagnostic device 40 is completed means the time when the diagnosis of the presence or absence of malfunction (fixed ON abnormality and fixed OFF abnormality) is completed for each of the positive side relay 36 and the negative side relay 38. In other words, the relay diagnostic device 40 completes the diagnosis of the operation of the system main relay 34 within one trip. Note that hereinafter, the presence of at least one of a fixed ON abnormality and a fixed OFF abnormality may be collectively referred to as an "operation malfunction."

[0038] The time when the hybrid vehicle 10 enters the Ready ON state is t4, and the time when the hybrid vehicle 10 enters the Ready OFF state is t5. The time t4 is a time after the time t3 when the ON signal is sent to the negative side relay 38. The time t5 is a time before the time t6 when the DCDC converter 32 is turned OFF and after the time t4.

[0039] As shown in FIG. 3 , the control system 50 includes an information acquisition section 52 , a motor control unit 54 , an engine control unit 56 , a relay control unit 58 , a converter control unit 62 , and a diagnostic unit 64 .

[0040] <<<<Information Acquisition Unit>>> The information acquisition unit 52 acquires various types of information used in the processing performed by the control system 50. In addition, the information acquisition unit 52 outputs the acquired information to the motor control unit 54, the engine control unit 56, the relay control unit 58, the converter control unit 62, and the diagnosis unit 64.

[0041] 2 and 3 , the motor control unit 54 controls the operation of the traction motor 18. For example, the motor control unit 54 controls the operation of the switching elements of the inverter 24 to control the supply of power between the traction motor 18 and the main battery 26. In this way, the motor control unit 54 can control the generation of power and electricity by the traction motor 18.

[0042] <<<Engine Control Unit>>> The engine control unit 56 controls the operation of the engine 12. For example, the engine control unit 56 controls the throttle opening, ignition timing, fuel injection amount, etc. by controlling the operation of each part of the engine 12. In this way, the engine control unit 56 can control the output of the engine 12. The engine control unit 56 also controls the operation of the ISG 13. Specifically, the engine control unit 56 can control the restart of the engine 12 by the ISG 13 by controlling the supply of power from the sub-battery 28 to the ISG 13.

[0043] <<<Relay Control Unit>>> The relay control unit 58 controls the ON operation (closing operation) and OFF operation (opening operation) of the system main relay 34. The ON operation of the system main relay 34 means that the positive side relay 36 and the negative side relay 38 are switched from OFF to ON. The OFF operation of the system main relay 34 means that the positive side relay 36 and the negative side relay 38 are switched from ON to OFF.

[0044] When the relay control unit 58 performs an ON operation on the system main relay 34, it transmits an ON signal to the system main relay 34. When the relay control unit 58 performs an OFF operation on the system main relay 34, it transmits an OFF signal to the system main relay 34.

[0045] <<<Converter Control Unit>>> The converter control unit 62 controls the operation of the DCDC converter 32. Specifically, the converter control unit 62 controls the operation of the switching elements of the DCDC converter 32, thereby controlling the supply of power between the main battery 26 and the sub-battery 28.

[0046] <<<Diagnostic Unit>>> The diagnostic unit 64 diagnoses whether or not there is a malfunction in the system main relay 34. Specifically, the diagnostic unit 64 diagnoses whether or not there is a malfunction in the positive side relay 36 and whether or not there is a malfunction in the negative side relay 38. The diagnosis result by the diagnostic unit 64 is notified to the driver, for example, by lighting a lamp provided on the instrument panel of the hybrid vehicle 10.

[0047] 4, the motor control unit 54, the engine control unit 56, the relay control unit 58, the converter control unit 62, and the diagnostic unit 64 each have a microcontroller 72 equipped with a processor 73 and a main memory 74. The main memory 74 stores a predetermined program.

[0048] The processor 73 and the main memory 74 are connected to each other so that they can communicate with each other. The processor 73 reads a predetermined program from the main memory 74, expands it, and executes it, thereby executing the program. Note that multiple processors 73 may be incorporated into the microcontroller 72. Also, multiple main memories 74 may be incorporated into the microcontroller 72.

[0049] The motor control unit 54, engine control unit 56, relay control unit 58, and converter control unit 62 each have an input circuit 76, a drive circuit 77, a communication circuit 78, an external memory 79, and a power supply circuit 81. The diagnostic unit 64 also has an input circuit 76, a communication circuit 78, an external memory 79, and a power supply circuit 81. The input circuit 76 converts signals input from various sensors into signals that can be input to the microcontroller 72. The drive circuit 77 generates drive signals for various devices including the engine 12 described above, based on signals output from the microcontroller 72.

[0050] The communication circuit 78 converts signals output from the microcontroller 72 into communication signals directed to other control units. The communication circuit 78 is connected to other control units via an in-vehicle network 83 such as a CAN (Controller Area Network) so that they can communicate with each other. The communication circuit 78 also converts communication signals received from other control units into signals that can be input to the microcontroller 72.

[0051] The power supply circuit 81 supplies power supply voltage to the microcontroller 72, the input circuit 76, the drive circuit 77, the communication circuit 78, the external memory 79, etc. The external memory 79 is made up of a non-volatile memory, etc. The external memory 79 stores programs, various data, etc.

[0052] 2 , the control system 50 can execute a plurality of steps for diagnosing the system main relay 34. Specifically, the control system 50 outputs an ON signal to the DCDC converter 32 when the positive side relay 36 and the negative side relay 38 are in the OFF state (open state). Then, the control system 50 can execute a step of adjusting the voltage VA of the DCDC converter 32 to the voltage of the main battery 26.

[0053] When the DC-DC converter 32 is in the ON state, the control system 50 outputs an ON signal to the positive relay 36. The control system 50 can then execute a step of diagnosing that the positive relay 36 is stuck OFF abnormally when it cannot detect both the voltage VB of the second voltage sensor 44 and the voltage VC of the third voltage sensor 46. Note that "when no voltage can be detected" refers to when the resistance value is infinite, and when the tester is over-range.

[0054] When the DCDC converter 32 and the positive side relay 36 are in the ON state, the control system 50 outputs an ON signal to the negative side relay 38, and then outputs an OFF signal to the DCDC converter 32. The control system 50 is then capable of executing a step of diagnosing that the negative side relay 38 is stuck OFF abnormally when the voltage VA at the first voltage sensor 42 drops.

[0055] The control system 50 maintains the DC-DC converter 32 in an OFF state and the positive relay 36 in an ON state. After outputting an OFF signal to the negative relay 38, the control system 50 can execute a step of diagnosing that the negative relay 38 is stuck ON abnormally if the voltage VA of the first voltage sensor 42 does not decrease.

[0056] The control system 50 keeps the DC-DC converter 32 in an OFF state and the negative side relay 38 in an OFF state. After outputting an OFF signal to the positive side relay 36, the control system 50 can execute a step of diagnosing that the positive side relay 36 is stuck ON abnormally when the voltage VC is 0 (V).

[0057] [Operation of First Embodiment] <Relay Diagnostic Control: Flowchart> The following describes the procedure for executing relay (system main relay 34) diagnostic control. FIGS. 6 and 7 are flowcharts showing an example of the procedure for executing relay diagnostic control. The flowcharts shown in FIGS. 6 and 7 are connected at terminals A to E. The terminal F is used in a second embodiment, which will be described later. Each step of the relay control shown in FIGS. 6 and 7 is executed by a processor 73 that constitutes the control system 50. Note that for each configuration and each voltage of the hybrid vehicle 10, reference should be made to FIGS. 1 to 5, and individual figure numbers will be omitted.

[0058] 6, the control system 50 proceeds to step S10, where it outputs an ON signal to the DCDC converter 32 while the positive relay 36 and the negative relay 38 are in the OFF state. Then, it proceeds to step S12.

[0059] In step S12, the control system 50 adjusts the voltage VA of the DCDC converter 32 to match the voltage of the main battery 26 based on the voltage of the main battery 26 detected by the sensor 26A. Then, the process proceeds to step S14.

[0060] In step S14, with the DC-DC converter 32 in the ON state, the control system 50 outputs an ON signal to the positive electrode side relay 36. Then, the process proceeds to step S16.

[0061] In step S16, the control system 50 determines whether or not both the voltage VB and the voltage VC are detectable. If at least one of the voltages VB and VC is detectable (S16: Yes), such as when VB=V2 and VC=0 (V), the control system 50 proceeds to step S18. If neither the voltage VB nor the voltage VC is detectable (S16: No), the control system 50 proceeds to step S28.

[0062] In step S18, while the DC-DC converter 32 and the positive side relay 36 are both in the ON state, the control system 50 outputs an ON signal to the negative side relay 38. Then, the process proceeds to step S20.

[0063] In step S20, the control system 50 outputs an OFF signal to the DCDC converter 32 and determines whether the voltage VA has dropped from the voltage V1. If the voltage VA has not dropped from the voltage V1 (S20: Yes), the control system 50 proceeds to step S22. If the voltage VA has dropped from the voltage V1 (S20: No), the control system 50 proceeds to step S30.

[0064] In step S22, the control system 50 outputs an OFF signal to the negative relay 38 and determines whether the voltage VA has dropped from the voltage V1. If the voltage VA has dropped from the voltage V1 (S22: Yes), the process proceeds to step S24. If the voltage VA has not dropped from the voltage V1 (S22: No), the process proceeds to step S32.

[0065] 7, in step S24, the control system 50 outputs an OFF signal to the positive electrode relay 36 and determines whether the voltage VC cannot be detected or whether the voltage VC is 0 (V). If the voltage VC cannot be detected (S24: Yes), the process proceeds to step S26. If the voltage VC is 0 (V) (S24: No), the process proceeds to step S34.

[0066] In step S26, the control system 50 displays the diagnosis result that there is no malfunction in the system main relay 34 (positive side relay 36 and negative side relay 38). For example, this may be displayed by turning on a lamp that indicates the good state of the relay, which is provided in part of the instrument panel, or by displaying "good operation" on the touch panel. The program then ends. The diagnosis result as to whether there is a malfunction in the system main relay 34 is recorded as diagnostic information in the external memory 79.

[0067] In step S28, the control system 50 displays the diagnosis result that the positive relay 36 is in an OFF-stuck abnormal state, and records the diagnosis result in the external memory 79. The program then ends. The method for displaying the diagnosis result may be the same as that in step S26.

[0068] In step S30, the control system 50 displays the diagnosis result that the negative relay 38 is in an OFF-stuck abnormal state, and records the diagnosis result in the external memory 79. The program then ends. The method for displaying the diagnosis result may be the same as that in step S26.

[0069] In step S32, the control system 50 displays the diagnosis result that the negative relay 38 is in an ON-stuck abnormal state, and records the diagnosis result in the external memory 79. Then, the program ends. The method for displaying the diagnosis result may be the same as that in step S26.

[0070] In step S34, the control system 50 displays the diagnosis result that the positive relay 36 is in an ON-stuck abnormal state, and records the diagnosis result in the external memory 79. The program then ends. The method for displaying the diagnosis result may be the same as that in step S26.

[0071] 5 shows the ON and OFF states of the system main relay 34 at each time and the detected voltages VA, VB, and VC. Note that for each configuration of the hybrid vehicle 10, reference should be made to FIGS. 1, 2, 3, and 4, and individual figure numbers will not be included.

[0072] The intervals between times t1 to t9 shown in Fig. 5, i.e., the lengths of time, are merely examples and are not limited to the times shown in the figures. Note that there is a time lag between when the control system 50 transmits a control signal to a controlled object and when the controlled object starts to operate, but this time lag is omitted in Fig. 5.

[0073] 5 shows the time when an ON signal and an OFF signal are transmitted to the positive side relay 36. In other words, graph G1 does not indicate whether the positive side relay 36 is in the ON state or the OFF state.

[0074] Graph G2 shows the time when an ON signal or an OFF signal is sent to the negative side relay 38. In other words, graph G2 does not indicate that the negative side relay 38 is in the ON state or the OFF state.

[0075] Graph G3 represents the voltage VA detected by the first voltage sensor 42. Graph G6 represents the voltage VB detected by the second voltage sensor 44. Graph G7 represents the voltage VC detected by the third voltage sensor 46. Graphs G4 and G5, indicated by dotted lines in Fig. 5, are graphs showing behavior different from that of graph G3.

[0076] In FIG. 5, hatched areas SA, SB, SC, and SD are areas where voltage cannot be detected.

[0077] As shown in Figure 5, the positive relay 36 and the negative relay 38 are both in the OFF state until just before time t1. The DC-DC converter 32 is in the OFF state. Furthermore, the voltages VA, VB, and VC cannot be detected. Here, if the voltage VC becomes 0 (V) by time t2 (as indicated by the dotted line), it is understood that the positive relay 36 is in a state of stuck-ON abnormality. In other words, it is understood that the positive relay 36 is in a state in which it cannot perform an OFF operation.

[0078] When the DC-DC converter 32 is turned on at time t1, the voltage VA rises to the voltage V1. If the positive relay 36 does not have a stuck-on abnormality, the voltages VB and VC cannot be detected.

[0079] When an ON signal is sent to the positive relay 36 at time t2, if the positive relay 36 is operating normally, the state of the positive relay 36 will be ON. The voltage VA will become voltage V1. The voltage VB will rise to voltage V2. The voltage VC will become 0 (V). Here, if the voltages VB and VC cannot be detected, it is understood that the positive relay 36 is in a state of stuck OFF abnormality. In other words, it is understood that the positive relay 36 is in a state where it cannot perform an ON operation.

[0080] When an ON signal is sent to the negative relay 38 at time t3, if the operation of the negative relay 38 is normal, the state of the negative relay 38 becomes ON. The voltage VA becomes voltage V1. The voltage VB becomes voltage V2. The voltage VC becomes 0 (V).

[0081] At time t6, the DC-DC converter 32 is turned off. If the voltage VA drops as shown in graph G4, it is clear that the negative relay 38 is stuck off. In other words, it is clear that the negative relay 38 is in a state where it cannot turn on.

[0082] When an OFF signal is sent to the negative relay 38 at time t7, if the negative relay 38 is operating normally, the negative relay 38 will be in the OFF state. At this time, voltage VA drops from voltage V1. Voltage VB becomes voltage V2. Voltage VC becomes 0 (V). Here, if voltage VA is maintained at voltage V1 as shown in graph G5, it can be seen that the negative relay 38 is in a state of stuck-ON abnormality. In other words, it can be seen that the negative relay 38 is in a state where it cannot perform an OFF operation.

[0083] When an OFF signal is sent to the positive relay 36 at time t8, if the positive relay 36 is operating normally, the positive relay 36 will be in the OFF state. At this time, the voltage VA remains lower than the voltage V1. The voltage VB becomes the voltage V2. The voltage VC cannot be detected. Here, if the voltage VC is 0 (V), it is understood that the positive relay 36 is in a stuck-ON abnormal state.

[0084] Summary of First Embodiment As described above, in the relay diagnostic device 40, the control system 50 outputs an ON signal to the positive relay 36. Then, when the relay diagnostic device 40 cannot detect both the voltage VB and the voltage VC, it diagnoses that the positive relay 36 is in a state of stuck-off abnormality. The control system 50 stops the operation of the DCDC converter 32 after outputting an ON signal to the negative relay 38, and when the voltage VA drops, it diagnoses that the negative relay 38 is in a state of stuck-off abnormality.

[0085] The control system 50 diagnoses that the negative relay 38 is in a stuck-ON abnormal state if the voltage VA does not decrease after outputting an OFF signal to the negative relay 38. The control system 50 diagnoses that the positive relay 36 is in a stuck-ON abnormal state if the voltage VC is 0 (V) after outputting an OFF signal to the positive relay 36.

[0086] In this way, the relay diagnostic device 40 executes each step so that the DCDC converter 32 is turned ON and OFF once per diagnosis. In other words, the relay diagnostic device 40 diagnoses whether or not there is a malfunction in the positive side relay 36 and whether or not there is a malfunction in the negative side relay 38 within one trip. In this way, the relay diagnostic device 40 can prevent the diagnosis of whether or not there is a malfunction in the positive side relay 36 and the negative side relay 38 from becoming complicated, compared to a configuration in which the DCDC converter 32 is turned ON and OFF multiple times.

[0087] Second Embodiment A relay diagnostic device 40 according to a second embodiment will be described below. Components identical or similar to those in the first embodiment are designated by the same reference numerals, and duplicate descriptions will be omitted. Individual reference numerals will be omitted for the configurations and voltages shown in FIGS. 1 to 5.

[0088] As shown in the flowcharts of Figures 6, 7 and 8, the relay diagnostic device 40 of the second embodiment differs in that steps S2 and S4 are added before step S10. Steps after step S10 are the same as those of the first embodiment, and therefore will not be described here.

[0089] The relay diagnostic device 40 of the second embodiment can execute a step of detecting the voltage VC with the third voltage sensor 46 before outputting an ON signal to the DCDC converter 32 and when an OFF signal is output to the positive relay 36. Furthermore, the relay diagnostic device 40 is programmed to diagnose whether or not the positive relay 36 is malfunctioning (stuck-ON abnormality) by proceeding to the next step depending on the value of the detected voltage VC before outputting an ON signal to the DCDC converter 32. For example, if the voltage VC detected by the third voltage sensor 46 is 0 (V), the positive relay 36 is diagnosed as being in a stuck-ON abnormality state.

[0090] 8 , in step S2, before outputting an ON signal to the DC-DC converter 32 and while an OFF signal is being output to the positive-side relay 36, the control system 50 detects the voltage VC using the third voltage sensor 46. Then, the process proceeds to step S4.

[0091] In step S4, the control system 50 determines whether the voltage VC is not 0 V. If the voltage VC is not 0 V (S4: Yes), the control system 50 proceeds to step S10. If the voltage VC is 0 V (S4: No), the control system 50 proceeds to step S34.

[0092] Before the DC-DC converter 32 is turned on, it is normal for the positive relay 36 to be in the off state. Here, when the voltage VC is 0 (V), the control system 50 diagnoses the positive relay 36 as having a stuck-on abnormality because the positive relay 36 is in the on state. In this way, in the second embodiment, it is possible to diagnose a malfunction of the positive relay 36 before one trip. Note that the operation of each step from step S10 onwards is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0093] [Modifications] The embodiments of the present invention are not limited to the first and second embodiments, and it goes without saying that various modifications are possible without departing from the gist of the invention.

[0094] As a modified example, a hybrid vehicle 10 equipped with a relay diagnostic device 90 may be used, as shown in Fig. 9. Note that components that are the same as or similar to those in the first and second embodiments are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0095] The relay diagnostic device 90 is an example of a vehicle relay diagnostic device. The relay diagnostic device 90 diagnoses the presence or absence of malfunctions (stuck-ON abnormality and stuck-OFF abnormality) within one trip for the positive relay 36 and the negative relay 38. The relay diagnostic device 90 includes, as an example, a first voltage sensor 42, a second voltage sensor 44, a third voltage sensor 46, and a control system 50.

[0096] The relay diagnostic device 90 differs from the relay diagnostic device 40 of the first embodiment in that the configuration of the positive side and the configuration of the negative side are interchanged. That is, the positive relay 36 is an example of a second relay, and the negative relay 38 is an example of a first relay. The first voltage sensor 42 is the same as in the first embodiment. The third voltage sensor 46 detects the voltage VC between the terminals of the negative relay 38.

[0097] Specifically, the second voltage sensor 44 is connected to the wiring 33B between the positive side relay 36 and the main battery 26, and is also connected to the wiring 35A between the negative side relay 38 and the DCDC converter 32. The second voltage sensor 44 detects a voltage VB that is a potential difference between the first power line 33 between the positive side relay 36 and the main battery 26 and the second power line 35 between the negative side relay 38 and the DCDC converter 32.

[0098] 10 shows graphs GA, GB, GC, GD, GE, GF, and GG for the relay diagnostic device 90. Graph GA represents the timing of transmission of an ON signal and an OFF signal to the negative side relay 38. Graph GB represents the timing of transmission of an ON signal and an OFF signal to the positive side relay 36. Graph GC represents voltage VA. Graph GD represents a state in which voltage VA decreases when the DCDC converter 32 is turned OFF. Graph GE represents a state in which voltage VA is maintained when the positive side relay 36 is turned OFF. Graph GF represents voltage VB. Graph GG represents voltage VC.

[0099] Note that explanation of graphs GA, GB, GC, GD, GE, GF, and GG will be omitted because they show similar trends to graphs G1, G2, G3, G4, G5, G6, and G7 of relay diagnostic device 40. In this way, the modified relay diagnostic device 90 can also diagnose the presence or absence of malfunctions (sticking ON abnormality and sticking OFF abnormality) for the positive side relay 36 and the negative side relay 38 within one trip.

[0100] The vehicle is not limited to the hybrid vehicle 10, but may also be an electric vehicle (EV).

[0101] When diagnosing that the voltage VC is 0 (V), even if the detected voltage is not 0 (V), it may be regarded as 0 (V) as long as it is a value within the range of measurement error with respect to 0 (V).

[0102] 10... hybrid vehicle (an example of a vehicle), 26... main battery (an example of a power storage unit), 32... DCDC converter (an example of a converter), 33... first power line, 35... second power line, 36... positive side relay (an example of a first relay), 38... negative side relay (an example of a second relay), 40... relay diagnostic device (an example of a vehicle relay diagnostic device), 42... first voltage sensor (an example of a first detection unit), 44... second voltage sensor (an example of a second detection unit), 46... third voltage sensor (an example of a third detection unit), 50... control system, 73... processor, 74... memory, 90... relay diagnostic device (an example of a vehicle relay diagnostic device), V1... voltage, V2... voltage, VA... voltage, VB... voltage, VC... voltage

Claims

1. A vehicle relay diagnostic device for diagnosing operation of a first relay and operation of a second relay in a vehicle in which a first power line on which a first relay is provided and a second power line of opposite polarity to the first power line on which a second relay is provided are connected to a power storage unit and a converter, the device comprising: a first detection unit that detects a voltage of the converter; a second detection unit that detects a voltage that is a potential difference between the first power line between the first relay and the converter and the second power line between the second relay and the power storage unit; a third detection unit that detects a voltage between terminals of the first relay; and a control system having a processor and a memory, for controlling the converter, the first relay, and the second relay, the control system comprising: a step of adjusting the voltage of the converter to the voltage of the power storage unit; a step of outputting an ON signal to the first relay when the converter is in an ON state; and a step of diagnosing that the first relay is stuck OFF abnormal when both the voltage detected by the second detection unit and the voltage between the terminals detected by the third detection unit cannot be detected.

1. A vehicle relay diagnostic device comprising: a step of outputting an ON signal to the second relay when the converter and the first relay are in an ON state; a step of outputting an OFF signal to the converter, and diagnosing the second relay as having an OFF-stuck abnormality when a voltage at the first detection unit drops; a step of diagnosing the second relay as having an ON-stuck abnormality when the voltage at the first detection unit does not drop after outputting an OFF signal to the second relay when the converter is in an OFF state and the first relay is in an ON state; and a step of diagnosing the first relay as having an ON-stuck abnormality when a voltage between terminals of the third detection unit is 0 (V) after outputting an OFF signal to the first relay when the converter is in an OFF state and the second relay is in an OFF state.

2. A vehicle relay diagnostic device as described in claim 1, wherein the control system executes the steps of: detecting a voltage between the terminals with the third detection unit before an ON signal is output to the converter and when an OFF signal is output to the first relay; and diagnosing that the first relay is stuck ON abnormally when the voltage between the terminals detected by the third detection unit is 0 (V).

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