Vehicle relay diagnostic device

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

Technical Field

[0004] , ,

[0006] , , , , , , , , , , , , ,

[0003] , , , , , ,

[0005]

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

Background Art

[0002] Diagnosis of the presence or absence of welding of a relay provided in a vehicle has been performed (see Patent Document 1, Patent Document 2, and Patent Document 3). In addition, vehicles provided with no pre-charge circuit for suppressing welding of a relay have been proposed (see Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When diagnosing the presence or absence of malfunction for a plurality of relays, in the configurations such as those of Patent Documents 1 and 2, in the diagnosis of one relay, it was necessary to turn on and off the converter at least once each. That is, for a plurality of relays, in order to diagnose the malfunction of each relay, it was necessary to turn on and off the converter a plurality of times, and there was room for improvement.

[0005] An object of the present invention is to suppress the complication of diagnosing the presence or absence of malfunction for a plurality of relays.

Means for Solving the Problems

[0006] A vehicle relay diagnostic device according to one embodiment diagnoses the operation of the first relay and the second relay in a vehicle in which a first power line on which a first relay is provided and a second power line on which a second relay is provided, having a different polarity from the first power line, connect a power storage unit and a converter. The vehicle relay diagnostic device includes a first detection unit that detects the voltage of the converter, a second detection unit that detects the voltage which is the 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 the voltage between the terminals of the first relay, and a control system that includes a processor and memory and controls the converter, the first relay and the second relay. The control system performs the following steps: to adjust the voltage of the converter to match the voltage of the energy storage unit; to output an ON signal to the first relay when the converter is ON; to diagnose that the first relay is stuck OFF if neither the voltage detected by the second detection unit nor the voltage between terminals detected by the third detection unit can be detected; to output an ON signal to the second relay when the converter and the first relay are ON; to diagnose that the second relay is stuck OFF if an OFF signal is output to the converter and the voltage at the first detection unit drops; to diagnose that the second relay is stuck ON if, after outputting an OFF signal to the second relay when the converter is OFF and the first relay is ON, the voltage at the first detection unit does not drop; and to diagnose that the first relay is stuck ON if, after outputting an OFF signal to the first relay when the converter is OFF and the second relay is OFF, the voltage between terminals of the third detection unit is 0(V). [Effects of the Invention]

[0007] In one embodiment of a vehicle relay diagnostic device, the control system executes each step such that the converter is turned ON and OFF once each. This prevents the diagnosis of malfunctions for multiple relays from becoming complicated. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a hybrid vehicle equipped with a relay diagnostic device according to the first embodiment. [Figure 2] This is a block diagram showing the schematic configuration of a hybrid vehicle equipped with a relay diagnostic device according to the first embodiment. [Figure 3] This is a block diagram showing an example of the functional configuration of a control system. [Figure 4] This is a diagram showing an example of the basic structure of a control unit. [Figure 5] This graph shows the ON / OFF switching times of the system main relay in the hybrid vehicle of the first embodiment, and the voltages detected at each time. [Figure 6] This flowchart shows the first half of the execution procedure in the relay diagnostic device of the first and second embodiments. [Figure 7] This flowchart shows the latter half of the execution procedure in the relay diagnostic device of the first and second embodiments. [Figure 8] This is a flowchart showing an example of the execution procedure in the relay diagnostic device of the second embodiment. [Figure 9] This is a block diagram showing the internal configuration of a hybrid vehicle equipped with a modified relay diagnostic device. [Figure 10] This graph shows the ON / OFF switching times of the system main relay in a modified hybrid vehicle, and the voltages detected at each time point. [Modes for carrying out the invention]

[0009] The first embodiment, the second embodiment, and modified examples will be described in detail below with reference to the drawings. In the following description, identical or substantially identical components and elements will be denoted by the same reference numerals, and repeated descriptions 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 the first embodiment. The hybrid vehicle 10 is an example of a vehicle. The hybrid vehicle 10 is equipped with a power train 16 including an engine 12 and a transmission 14. The power train 16 has an output shaft 19. A rear wheel 29 is connected to the output shaft 19 via a propeller shaft 21 and a rear differential 23.

[0011] Further, a front differential 25 is incorporated in the transmission 14. A front wheel 27 is connected to the front differential 25. Note that the hybrid vehicle 10 may be of any of a series type, a parallel type, or a series-parallel type. The power train 16 is a power train for all-wheel drive, but is not limited thereto, and a power unit for front-wheel drive or rear-wheel drive may 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] As shown in FIG. 2, the hybrid vehicle 10 includes an engine 12, a transmission 14, a traveling 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 is an abbreviation for Direct Current. Further, the hybrid vehicle 10 includes a relay diagnostic device 40.

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

[0015] <Engine> The engine 12 is an internal combustion engine that generates power using fuel such as gasoline. The engine 12 can output power for driving the front wheels 27 and the rear wheels 29 of the hybrid vehicle 10. The crankshaft, which is the output shaft of the engine 12, is connected to the transmission 14 via a torque converter or the like. The power output from the engine 12 is transmitted to the front wheels 27 and the rear wheels 29 after being shifted by the transmission 14.

[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 the sub-battery 28 as an example. The ISG 13 generates power using the electric power supplied from the sub-battery 28. Also, the ISG 13 can generate electricity using the power output from the engine 12. The sub-battery 28 can be charged by the electric power generated by the ISG 13.

[0017] <Transmission etc.> Inside the transmission 14, a traveling motor 18 or the like is provided. The traveling motor 18 is an electric motor. The traveling motor 18 is connected to the main battery 26 via an inverter 24. The traveling motor 18 can perform power running and regenerative running. During regenerative running, it converts kinetic energy into electric energy and charges the main battery 26 via the inverter 24. Also, the traveling motor 18 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 drive 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 sensor 26A. The main battery 26 is, for example, 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 a DC-DC converter 32. This allows the hybrid vehicle 10 to supply power stored in the main battery 26 to each device after the DC-DC converter 32 steps down the voltage. A system main relay 34, which will be described later, is provided between the main battery 26 and the DC-DC converter 32.

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

[0021] <DCDCコンバータ> The DC-DC converter 32 is an example of a converter connected to the main battery 26 via a first power line 33, a second power line 35, and a system main relay 34. The DC-DC converter 32 modifies 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 has wiring 33A and wiring 33B. Wiring 33A connects the DC-DC converter 32 to terminal A of the system main relay 34, which will be described later. Wiring 33B connects terminal B of the system main relay 34, which will be described later, to the main battery 26. The first power line 33 corresponds to the positive terminal wiring. One end of wiring 41 is connected to wiring 33A. The other end of wiring 41 is connected to the inverter 24.

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

[0024] <System Main Relay> The system main relay 34 can interrupt and connect the electrical connection between 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 (interrupted 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, the operation of closing the system main relay 34 will be referred to as the ON operation, and the operation of opening the system main relay 34 will be referred to as the OFF operation. Specifically, the system main relay 34 has a positive side relay 36 and a negative side relay 38. In the diagram, "SMRP" 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 terminals A and B. The positive-side relay 36 is installed on the first power line 33 between the main battery 26 and the DC-DC 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 side relay>> The negative-side relay 38 is an example of a second relay having terminals C and D. The negative-side relay 38 is installed in the second power line 35 between the main battery 26 and the DC-DC converter 32. The ON and OFF operations of the negative-side 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 the positive-side relay 36 and the negative-side relay 38 within the time TP of one trip, which will be described later. Specifically, the relay diagnostic device 40 diagnoses whether or not there is a malfunction in the positive-side relay 36 and the negative-side relay 38. In this embodiment, "malfunction" means "ON sticking abnormality and OFF sticking abnormality."

[0028] "ON sticking abnormality" means that even if the control system 50, described later, outputs an OFF signal to the positive-side relay 36 and the negative-side relay 38, the positive-side relay 36 and the negative-side relay 38 do not turn OFF. For example, this can occur when the positive-side relay 36 and the negative-side relay 38 are welded to their terminals.

[0029] "OFF sticking abnormality" means that even if the control system 50 outputs an ON signal to the positive-side relay 36 and the negative-side relay 38, the positive-side relay 36 and the negative-side relay 38 do not turn ON. For example, this can occur if there is a malfunction such as poor contact in the circuit that operates the positive-side relay 36 and the negative-side 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 the first detection unit. The first voltage sensor 42 detects the voltage on the main battery 26 side of the DC-DC converter 32. Specifically, the first voltage sensor 42 is connected to wiring 33A and wiring 35A near the input / output terminals of the DC-DC converter 32. Hereafter, 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 wiring 33A between the positive-side relay 36 and the DC-DC converter 32, and to wiring 35B between the negative-side relay 38 and the main battery 26. In other words, the second voltage sensor 44 detects the voltage which is the potential difference between the first power line 33 between the positive-side relay 36 and the DC-DC converter 32 and the second power line 35 between the negative-side relay 38 and the main battery 26. Hereafter, 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-side relay 36. In other words, the third voltage sensor 46 detects the voltage between terminal A and terminal B. Hereafter, the voltage between terminals detected by the third voltage sensor 46 will be 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 memory. The control system 50 controls the operation of the DC-DC 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 pressing the brake pedal, the control system 50 controls the hybrid vehicle 10 to a drivable state (Ready ON).

[0035] On the other hand, if the hybrid vehicle 10 is controlled to be in a drivable state and the driver presses the switch while pressing the brake pedal, the control system 50 controls the hybrid vehicle 10 to a stopped state (ReadyOFF).

[0036] As shown in Figures 2 and 5, in this embodiment, the period from when the DCDC converter 32 is turned ON until the diagnosis by the relay diagnostic device 40 is completed is referred to as "1 trip". In this embodiment, the time TP from time t1 to time t9 corresponds to the duration of 1 trip. Within 1 trip, the DCDC converter 32 is turned ON and OFF once each. In the figures, DCDCON and DCDCOFF represent the ON and OFF states of the DCDC converter 32.

[0037] The time at which the relay diagnostic device 40 completes its diagnosis refers to the time at which the diagnosis of malfunctions (ON sticking abnormalities and OFF sticking abnormalities) for each of the positive-side relay 36 and the negative-side relay 38 is completed. In other words, the relay diagnostic device 40 completes the diagnosis of the operation of the system main relay 34 within one trip. Hereafter, the presence of at least one of the ON sticking abnormalities and OFF sticking abnormalities may be collectively referred to as "malfunction."

[0038] Let t4 be the time when the hybrid vehicle 10 becomes Ready ON, and t5 be the time when it becomes Ready OFF. Time t4 is after time t3, when the ON signal was sent to the negative side relay 38. Time t5 is before time t6, when the DCDC converter 32 became OFF, and after time t4.

[0039] As shown in Figure 3, the control system 50 includes an information acquisition unit 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 section>>> The information acquisition unit 52 acquires various types of information used in the processing performed by the control system 50. The information acquisition unit 52 also outputs the acquired information to the motor control unit 54, engine control unit 56, relay control unit 58, converter control unit 62, and diagnostic unit 64.

[0041] <<<Motor control unit>>> As shown in Figures 2 and 3, the motor control unit 54 controls the operation of the travel motor 18. For example, the motor control unit 54 controls the power supply between the travel motor 18 and the main battery 26 by controlling the operation of the switching elements of the inverter 24. In this way, the motor control unit 54 can control the power generation and power generation by the travel 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, and fuel injection amount by controlling the operation of various parts 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 switch 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 switch from ON to OFF.

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

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

[0046] <<<Diagnostic Unit>>> The diagnostic unit 64 diagnoses whether the system main relay 34 is malfunctioning. Specifically, the diagnostic unit 64 diagnoses whether the positive side relay 36 is malfunctioning and whether the negative side relay 38 is malfunctioning. The diagnostic results from the diagnostic unit 64 are notified to the driver, for example, by illuminating a lamp on the instrument panel of the hybrid vehicle 10.

[0047] As shown in Figure 4, the motor control unit 54, engine control unit 56, relay control unit 58, converter control unit 62, and diagnostic unit 64 each have a microcontroller 72 equipped with a processor 73 and main memory 74, etc. A predetermined program is stored in the main memory 74.

[0048] The processor 73 and the main memory 74 are connected to each other in a way that allows them to communicate. The program is executed when the processor 73 reads a predetermined program from the main memory 74, expands it, and executes it. Note that the microcontroller 72 may incorporate multiple processors 73. Similarly, the microcontroller 72 may incorporate multiple main memory 74.

[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 aforementioned engine 12, based on signals output from the microcontroller 72.

[0050] The communication circuit 78 converts signals output from the microcontroller 72 into communication signals for other control units. The communication circuit 78 is connected to other control units via an in-vehicle network 83 such as CAN (Controller Area Network) to enable communication with them. 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 voltage to the microcontroller 72, input circuit 76, drive circuit 77, communication circuit 78, and external memory 79, etc. The external memory 79 consists of non-volatile memory, etc. Programs and various data are stored in the external memory 79.

[0052] In the hybrid vehicle 10 shown in Figure 2, the control system 50 can perform several 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). The control system 50 can then perform the step of matching the voltage VA of the DCDC converter 32 to the voltage of the main battery 26.

[0053] The control system 50 outputs an ON signal to the positive side relay 36 when the DC-DC converter 32 is ON. The control system 50 can then perform a step to diagnose that the positive side relay 36 is stuck OFF if neither the voltage VB of the second voltage sensor 44 nor the voltage VC of the third voltage sensor 46 can be detected. Note that "when voltage cannot be detected" means when the resistance value is infinite, which is when the tester goes over range.

[0054] When the DC-DC converter 32 and the positive-side relay 36 are ON, the control system 50 outputs an ON signal to the negative-side relay 38, and then outputs an OFF signal to the DC-DC converter 32. The control system 50 can then perform the step of diagnosing that the negative-side relay 38 is stuck in the OFF position when the voltage VA at the first voltage sensor 42 drops.

[0055] The control system 50 maintains the DC-DC converter 32 in the OFF state and the positive side relay 36 in the ON state. After outputting an OFF signal to the negative side relay 38, the control system 50 can perform the step of diagnosing that the negative side relay 38 is stuck ON 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 the OFF state and the negative side relay 38 in the OFF state. After outputting an OFF signal to the positive side relay 36, the control system 50 can perform a step to diagnose that the positive side relay 36 is stuck ON if the voltage VC is 0 (V).

[0057] [Operation of the First Embodiment] <Relay Diagnostic Control: Flowchart> The following describes the procedure for executing relay (system main relay 34) diagnostic control. Figures 6 and 7 are flowcharts showing an example of the procedure for executing relay diagnostic control. The flowcharts shown in Figures 6 and 7 are connected by terminals labeled A through E. Terminal labeled F is used in the second embodiment described later. Furthermore, each step of the relay control shown in Figures 6 and 7 is executed by the processor 73 that constitutes the control system 50. For the configuration and voltages of the hybrid vehicle 10, please refer to Figures 1 through 5, and the individual figure numbers will not be listed.

[0058] As shown in Figure 6, the control system 50 proceeds to step S10, where it outputs an ON signal to the DC-DC converter 32 with the positive relay 36 and negative relay 38 in the OFF position. Then it proceeds to step S12.

[0059] In step S12, the control system 50 adjusts the voltage VA of the DC-DC 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, it proceeds to step S14.

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

[0061] In step S16, the control system 50 determines whether both voltage VB and voltage VC cannot be detected. For example, if at least one of voltage VB and voltage VC can be detected (S16: Yes), such as when VB = V2 and VC = 0 (V), the system proceeds to step S18. If neither voltage VB nor voltage VC can be detected (S16: No), the system proceeds to step S28.

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

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

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

[0065] As shown in Figure 7, in step S24, the control system 50 outputs an OFF signal to the positive side relay 36 to determine 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 system proceeds to step S26. If the voltage VC is 0 (V) (S24: No), the system proceeds to step S34.

[0066] In step S26, the control system 50 displays a diagnostic result indicating that there are no malfunctions in the system main relay 34 (positive-side relay 36 and negative-side relay 38). For example, this can be done by lighting up a lamp on the instrument panel that indicates the relay is functioning correctly, or by displaying a "functioning correctly" message on the touch panel. The program then terminates. The diagnostic result regarding the presence or absence of malfunctions 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 diagnostic result that the positive side relay 36 is in an OFF stuck state and records the diagnostic result in the external memory 79. Then, it terminates the program. The method of displaying the diagnostic result may be the same as in step S26.

[0068] In step S30, the control system 50 displays the diagnostic result that the negative-side relay 38 is in an OFF stuck state and records the diagnostic result in the external memory 79. Then, it terminates the program. The method of displaying the diagnostic result may be the same as in step S26.

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

[0070] In step S34, the control system 50 displays the diagnostic result that the positive side relay 36 is in an abnormal ON-fixed state and records the diagnostic result in the external memory 79. Then, it terminates the program. The method of displaying the diagnostic result may be the same as in step S26.

[0071] Figure 5 shows the ON and OFF states of the system main relay 34 at each time point, as well as the detected voltages VA, VB, and VC. For details on the configuration of the hybrid vehicle 10, please refer to Figures 1, 2, 3, and 4, and the individual figure numbers are omitted.

[0072] The intervals between time points t1 and t9 shown in Figure 5, i.e., the length of time, are examples only and are not limited to the times shown. Note that there is a time lag between when the control system 50 transmits a control signal to the controlled object and when the controlled object begins operation, but this time lag is omitted in Figure 5.

[0073] Graph G1 shown in Figure 5 indicates the time when an ON signal and an OFF signal were 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 times when ON and OFF signals were transmitted to the negative-side relay 38. In other words, graph G2 does not indicate whether 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. In Figure 5, graphs G4 and G5, shown by dotted lines, represent cases where the behavior differs from that of graph G3.

[0076] In Figure 5, the shaded areas SA, SB, SC, and SD represent regions where voltage cannot be detected.

[0077] As shown in Figure 5, until just before time t1, the positive-side relay 36 and the negative-side relay 38 are both in the OFF state. The DC-DC converter 32 is also in the OFF state. Furthermore, voltages VA, VB, and VC cannot be detected. Here, if voltage VC = 0 (V) between now and time t2 (indicated by the dotted line), it can be seen that the positive-side relay 36 is in an abnormal ON-fixed state. In other words, it can be seen that the positive-side relay 36 is in a state where it cannot perform the OFF operation.

[0078] If the DC-DC converter 32 is turned ON at time t1, voltage VA rises to voltage V1. If there is no ON-fixation abnormality in the positive-side relay 36, voltages VB and VC cannot be detected.

[0079] If an ON signal is transmitted to the positive-side relay 36 at time t2, and the positive-side relay 36 is operating normally, then the state of the positive-side relay 36 will be ON. Voltage VA will become voltage V1. Voltage VB will rise to voltage V2. Voltage VC will become 0(V). If voltages VB and VC cannot be detected, it indicates that the positive-side relay 36 is stuck in the OFF position. In other words, it indicates that the positive-side relay 36 is unable to perform the ON operation.

[0080] At time t3, if an ON signal is transmitted to the negative-side relay 38, and the negative-side relay 38 is functioning correctly, the state of the negative-side relay 38 will be ON. Voltage VA will become voltage V1. Voltage VB will become voltage V2. Voltage VC will become 0 (V).

[0081] At time t6, the DC-DC converter 32 is turned OFF. Here, as shown in graph G4, if the voltage VA decreases, it can be seen that the negative side relay 38 is stuck in the OFF position. In other words, the negative side relay 38 is in a state where it cannot perform the ON operation.

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

[0083] At time t8, if an OFF signal is sent to the positive side relay 36, and the positive side relay 36 is operating normally, the state of the positive side relay 36 will be OFF. At this time, the voltage VA will remain lower than the voltage V1. The voltage VB will become the voltage V2. The voltage VC cannot be detected. Here, if the voltage VC is 0 (V), it can be seen that the positive side relay 36 is in an abnormal ON stuck state.

[0084] <Summary of the First Embodiment> As explained above, in the relay diagnostic device 40, the control system 50 outputs an ON signal to the positive side relay 36. The relay diagnostic device 40 then diagnoses that the positive side relay 36 is stuck in the OFF position if neither voltage VB nor voltage VC can be detected. The control system 50 outputs an ON signal to the negative side relay 38 and then stops the operation of the DC-DC converter 32. If the voltage VA drops, the control system 50 diagnoses that the negative side relay 38 is stuck in the OFF position.

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

[0086] In this way, the relay diagnostic device 40 executes each step so that the DCDC converter 32 is turned ON and OFF once each during a single diagnosis. In other words, the relay diagnostic device 40 diagnoses whether there is a malfunction in the positive side relay 36 and the negative side relay 38 within one trip. In this way, the relay diagnostic device 40 can suppress the complexity of diagnosing the presence or absence of malfunctions in the positive side relay 36 and the negative side relay 38 compared to a configuration in which the DCDC converter 32 is turned ON and OFF multiple times.

[0087] [Second Embodiment] The relay diagnostic device 40 of the second embodiment will be described below. Components identical or similar to those in the first embodiment are denoted by the same reference numerals, and redundant descriptions will be omitted. Individual figure numbers will be omitted for the configurations and voltages shown in Figures 1 to 5.

[0088] As shown in the flowcharts in 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 S10 onward are the same as in the first embodiment, so their explanation is omitted.

[0089] In the relay diagnostic device 40 of the second embodiment, the step of detecting the voltage VC with the third voltage sensor 46 can be performed before an ON signal is output to the DCDC converter 32 and when an OFF signal is output to the positive side relay 36. Furthermore, the relay diagnostic device 40 is programmed to diagnose whether or not there is a malfunction (ON sticking abnormality) in the positive side relay 36 by moving to the next step according to the detected voltage VC value 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), it is diagnosed that the positive side relay 36 is in an ON sticking abnormality state.

[0090] [Operation of the second embodiment] As shown in Figure 8, in step S2, the control system 50 detects the voltage VC with the third voltage sensor 46 before outputting an ON signal to the DC-DC converter 32 and when an OFF signal is output to the positive side relay 36. Then, it 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 system proceeds to step S10. If the voltage VC is 0(V) (S4:No), the system proceeds to step S34.

[0092] Before the DC-DC converter 32 turns ON, the positive-side relay 36 is normally in the OFF state. Here, the control system 50 diagnoses that there is an ON-fixed abnormality in the positive-side relay 36 because, when the voltage VC is 0 (V), the positive-side relay 36 is in the ON state. In this way, in the second embodiment, it is possible to diagnose a malfunction of the positive-side relay 36 before the first trip. Note that the operation of each step from step S10 onward is the same as in the first embodiment, so the explanation will be omitted.

[0093] [Variation] The embodiments of the present invention are not limited to the first and second embodiments, and it goes without saying that they can be modified in various ways without departing from the spirit of the invention.

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

[0095] The relay diagnostic device 90 is an example of a vehicle relay diagnostic device. The relay diagnostic device 90 diagnoses whether there are any malfunctions (ON sticking abnormalities and OFF sticking abnormalities) in the positive side relay 36 and the negative side relay 38 within one trip. 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 swapped. That is, the positive side relay 36 is an example of the second relay, and the negative side relay 38 is an example of the first relay. The first voltage sensor 42 is the same as in the first embodiment. The third voltage sensor 46 detects the voltage VC, which is the voltage between the terminals of the negative side relay 38.

[0097] Specifically, the second voltage sensor 44 is connected to wiring 33B between the positive-side relay 36 and the main battery 26, and to wiring 35A between the negative-side relay 38 and the DC-DC converter 32. The second voltage sensor 44 detects the voltage VB, which is the 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 DC-DC converter 32.

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

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

[0100] The vehicle is not limited to a hybrid vehicle 10; it may also be an electric vehicle (EV).

[0101] When diagnosing a voltage VC = 0(V), even if the detected voltage is not 0(V), it can be considered 0(V) if it is within the measurement error range relative to 0(V). [Explanation of Symbols]

[0102] 10...Hybrid vehicle (example of a vehicle), 26...Main battery (example of an energy storage unit), 32...DC-DC converter (example of a converter), 33...First power line, 35...Second power line, 36...Positive side relay (example of a first relay), 38...Negative side relay (example of a second relay), 40...Relay diagnostic device (example of a vehicle relay diagnostic device), 42...First voltage sensor (example of a first detection unit), 44...Second voltage sensor (example of a second detection unit), 46...Third voltage sensor (example of a third detection unit), 50...Control system, 73...Processor, 74...Memory, 90...Relay diagnostic device (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 the operation of the first relay and the second relay in a vehicle in which a first power line equipped with a first relay and a second power line having a different polarity from the first power line and equipped with a second relay are connected to a power storage unit and a converter, A first detection unit for detecting the voltage of the converter, A second detection unit detects a voltage which is the 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 energy storage unit. A third detection unit for detecting the voltage between the terminals of the first relay, It comprises a processor and memory, and a control system that controls the converter, the first relay and the second relay, The control system is The steps include: adjusting the voltage of the converter to match the voltage of the energy storage unit; The steps include: outputting an ON signal to the first relay while the converter is ON; If neither the voltage detected by the second detection unit nor the voltage between terminals detected by the third detection unit can be detected, the first relay is diagnosed as being stuck in the OFF position. The steps include outputting an ON signal to the second relay while the converter and the first relay are ON, The steps include outputting an OFF signal to the converter and diagnosing that the second relay is stuck in the OFF position when the voltage at the first detection unit drops, The steps include: diagnosing that the second relay is stuck in the ON position if, while the converter is OFF and the first relay is ON, the voltage at the first detection unit does not decrease after an OFF signal is output to the second relay; With the converter OFF and the second relay OFF, if an OFF signal is output to the first relay, and the voltage between the terminals of the third detection unit is 0 (V), the first relay is diagnosed as being stuck ON. Vehicle relay diagnostic device.

2. In the vehicle relay diagnostic device according to claim 1, The control system is Before an ON signal is output to the converter, and when an OFF signal is output to the first relay, the third detection unit detects the voltage between the terminals. The third detection unit determines that the voltage between terminals detected is 0 (V), and diagnoses that the first relay is stuck ON. Execute Vehicle relay diagnostic device.

Images