Relay life prediction device and relay life prediction system

Abstract

To provide a relay life prediction device and a relay life prediction system that predicts a lifespan of relays.SOLUTION: A prediction unit 602 of a relay life prediction device 60 in a relay life prediction system predicts a service life of a relay on the basis of a change in an operating voltage which is a coil voltage when a voltage applied to a target system rises to a voltage threshold in a case in which a relay switch is turned on from off, from when the relay is normal, and a change in a return voltage which is a coil voltage when a voltage applied to the target system drops to the voltage threshold when the relay switch is turned off from on, from when the relay is normal.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a relay life prediction device and a relay life prediction system. [Background technology]

[0002] As described in Patent Document 1, a power supply control device is known that includes a drive unit that turns a relay on and off, and a determination unit that determines whether the relay is operating abnormally based on the detection result of a current flowing through the relay coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-225132 A Summary of the Invention [Problem to be solved by the invention]

[0004] Considering the safety of a system in which a relay is installed, it is desirable to predict the life of a relay before it fails. However, the power supply control device described in Patent Document 1 determines whether a relay is operating abnormally, but does not predict the life of the relay.

[0005] An object of the present disclosure is to provide a relay life prediction device and a relay life prediction system for predicting the life of a relay. [Means for solving the problem]

[0006] The invention described in claim 1 is a relay life prediction device comprising: an acquisition unit (601) that acquires a value related to a target voltage (Vsys), which is a voltage applied to an object (10) from a relay (30) having a coil (305) and a switch (330) that applies a voltage to the object (10) when turned on by an electromagnetic force caused by a current flowing through the coil; and a value related to an operating voltage (VS), which is the coil voltage (Vc) when the target voltage increases to a voltage threshold (Vsys_th) when the switch is turned on from off; and a prediction unit (602) that predicts the life of the relay based on a change in the operating voltage from when the relay is normal.

[0007] The invention described in claim 4 is a relay life prediction device including an acquisition unit (601) that acquires a value related to a target voltage (Vsys), which is a voltage applied to an object from a relay (30) having a coil (305) and a switch (330) that applies a voltage to the object (10) when turned on by an electromagnetic force caused by a current flowing through the coil, and a value related to a return voltage (VR), which is the coil voltage (Vc) when the target voltage drops to a voltage threshold (Vsys_th) when the switch is turned from on to off, and a prediction unit (602) that predicts the life of the relay based on a change in the return voltage from when the relay was normal.

[0008] Furthermore, the invention described in claim 9 is a relay life prediction system including: a relay (30) having a coil (305); and a switch (330) that applies a voltage to an object (10) when turned on by an electromagnetic force caused by a current flowing through the coil; an acquisition unit (601) that acquires a value related to a target voltage (Vsys) that is a voltage applied from the relay to the object; and a value related to an operating voltage (VS) that is the coil voltage (Vc) when the target voltage increases and reaches a voltage threshold (Vsys_th) when the switch is turned on from off; and a prediction unit (602) that predicts the life of the relay based on a change in the operating voltage from when the relay is normal.

[0009] The invention described in claim 10 is a relay life prediction system including: a relay (30) having a coil (305); and a switch (330) that applies a voltage to an object (10) when turned on by an electromagnetic force caused by a current flowing through the coil; an acquisition unit (601) that acquires a value related to a target voltage (Vsys) that is a voltage applied from the relay to the object, and a value related to a return voltage (VR) that is the coil voltage (Vc) when the target voltage drops to a voltage threshold (Vsys_th) when the switch is turned from on to off; and a prediction unit (602) that predicts the life of the relay based on a change in the return voltage from when the relay was normal.

[0010] With the above configuration, the life of the relay can be predicted since the activation voltage or release voltage changes when the life of the relay becomes shorter.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0012] [Figure 1] 1 is a configuration diagram of a vehicle system in which a relay life prediction device and a relay life prediction system according to an embodiment are used; [Diagram 2] FIG. 2 is a cross-sectional view of a relay in the relay life prediction system. [Diagram 3] FIG. 2 is a block diagram of a relay life prediction device. [Figure 4] 4 is a time chart for explaining the processing of the relay life predicting device. [Diagram 5] FIG. 2 is an enlarged cross-sectional view of a relay when the movable contact and the fixed contact are worn. [Figure 6] 13 is an enlarged cross-sectional view of a relay when protrusions are formed on the movable contact and the fixed contact. [Figure 7] 4 is a time chart for explaining the processing of the relay life predicting device. [Figure 8]4 is a time chart for explaining the processing of the relay life predicting device. [Figure 9] 4 is a time chart for explaining the processing of the relay life predicting device. [Figure 10] 4 is a table for explaining the processing of the relay life prediction device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals, and the description thereof will be omitted.

[0014] A relay life prediction device 60 according to the embodiment is used, for example, in a vehicle system 1. First, the vehicle system 1 will be described.

[0015] 1, the vehicle system 1 includes a power supply 5, a target system 10, and a relay life prediction system 20. The target system 10 corresponds to an object, and is a system that affects the running of the vehicle when the power supply from the power supply 5 is stopped, such as an automatic driving system for the vehicle.

[0016] The relay life prediction system 20 includes a fuse 25, a relay 30, a driving unit 40, a ground 45, and a relay life prediction device 60.

[0017] One end of the fuse 25 is connected to the power source 5. The other end of the fuse 25 is connected to a relay 30, which will be described later. The fuse 25 prevents an overcurrent from flowing from the power source 5 through the relay 30, which will be described later, to the target system 10 and a drive unit 40, which will be described later, etc.

[0018] As shown in FIG. 2, the relay 30 includes a bobbin 300, a coil 305, a first coil terminal 311, a second coil terminal 312, a core 315, a yoke 320, a switch 330, a first switch terminal 351, a second switch terminal 352, and a case 355.

[0019] The bobbin 300 is formed into a cylindrical shape from, for example, resin or the like, and thus has electrical insulation properties.

[0020] The coil 305 has an electric resistance and an inductance, and generates a magnetic force when energized. The coil 305 is wound around the bobbin 300. The first coil terminal 311 is connected to one end of the coil 305 and to the other end of the fuse 25. The second coil terminal 312 is connected to the other end of the coil 305 and to a drive unit 40 described later. The connection between the first coil terminal 311 and the second coil terminal 312 is not limited thereto, and the first coil terminal 311 may be connected to the drive unit 40 described later. The second coil terminal 312 may be connected to the other end of the fuse 25.

[0021] The core 315 is made of a magnetic material such as metal to form a magnetic path. The core 315 is formed in a cylindrical shape centered on the coil axis CL. The core 315 is inserted into a hole in the bobbin 300.

[0022] The yoke 320 is made of a magnetic material such as metal to form a magnetic path. The yoke 320 extends in the direction of the coil axis CL and in a direction perpendicular to the direction of the coil axis CL to form an L-shape. The yoke 320 is fixed to an end of the core 315 by crimping.

[0023] The switch 330 is turned on and off by an electromagnetic force generated by a current flowing through the coil 305. Specifically, the switch 330 has an armature plate 332, a leaf spring 334, a movable contact 336, a fixed contact 338, and a stopper 340.

[0024] The armature plate 332 is made of a magnetic material such as metal, and thus forms a magnetic path. The armature plate 332 is supported on an end of the yoke 320, and thus rotates about a contact point between the armature plate 332 and the end of the yoke 320 as a fulcrum. A portion of the armature plate 332 on the opposite side to the fulcrum faces the core 315 in the direction of the coil axis CL. A core plate gap 345 is formed between the armature plate 332 and the core 315 in the direction of the coil axis CL.

[0025] The leaf spring 334 corresponds to an elastic member, is formed in a plate shape, and is elastically deformable. The leaf spring 334 is formed in an L-shape along the armature plate 332 and the yoke 320. The leaf spring 334 is fixed to the armature plate 332 by crimping at a portion along the armature plate 332. The leaf spring 334 protrudes from a contact portion with the armature plate 332 in a direction perpendicular to the coil axis CL direction on the opposite side of the fulcrum of the armature plate 332. The leaf spring 334 is fixed to the yoke 320 by crimping at a portion along the yoke 320. The leaf spring 334 applies an elastic force to the armature plate 332 in a direction in which the armature plate 332 moves away from the core 315 by elastic deformation.

[0026] The movable contact 336 corresponds to the movable part, and the fixed contact 338 corresponds to the fixed part. The movable contact 336 faces the fixed contact 338 in the coil axis CL direction. A contact gap 350 is formed between the movable contact 336 and the fixed contact 338 in the coil axis CL direction. The movable contact 336 is fixed to the protruding end of the leaf spring 334. Therefore, the movable contact 336 receives an elastic force from the leaf spring 334 in a direction in which the movable contact 336 moves away from the fixed contact 338. The stopper 340 is disposed at a position where the movable contact 336 is sandwiched between the fixed contact 338 and the stopper 340 in the coil axis CL direction. Thus, the stopper 340 supports the movable contact 336 in the initial state of the relay 30.

[0027] The first switch terminal 351 is connected to the fixed contact 338 and is also connected to the other end of the fuse 25. The second switch terminal 352 is connected to the movable contact 336 via the leaf spring 334 and is also connected to the target system 10. The connection between the first switch terminal 351 and the second switch terminal 352 is not limited to this, and the first switch terminal 351 may be connected to the movable contact 336 via the leaf spring 334 and is also connected to the target system 10. The second switch terminal 352 may be connected to the fixed contact 338 and is also connected to the other end of the fuse 25.

[0028] The case 355 is formed into a box shape from, for example, resin, and houses the bobbin 300, the coil 305, the core 315, the yoke 320, the armature plate 332, the leaf spring 334, the movable contact 336, the fixed contact 338, and the stopper 340. In addition, the first coil terminal 311, the second coil terminal 312, the first switch terminal 351, and the second switch terminal 352 protrude from the case 355 in the direction of the coil axis CL.

[0029] Returning to Fig. 1, the driving unit 40 is a constant current circuit constituted by, for example, an electric resistor, a transistor, a Zener diode, etc. The driving unit 40 is also connected to the second coil terminal 312, a ground 45, and a relay life prediction device 60 described below. Although a transistor is given as the semiconductor switch of the constant current circuit of the driving unit 40, the present invention is not limited thereto, and the semiconductor switch may be a MOSFET or the like instead of a transistor.

[0030] The relay life prediction device 60 is mainly composed of, for example, a microcomputer, and includes a CPU, a ROM, a flash memory, a RAM, an I / O, a drive circuit, an A / D converter, and a bus line connecting these components, etc. As shown in Fig. 3, the relay life prediction device 60 includes a first voltage detection unit 51, a second voltage detection unit 52, a control unit 600, an acquisition unit 601, and a prediction unit 602 as functional blocks.

[0031] The first voltage detection unit 51 is, for example, a comparator circuit, and detects the voltage applied to the coil 305 from the power source 5 via the fuse 25. The first voltage detection unit 51 also outputs a signal corresponding to the detected voltage to the acquisition unit 601.

[0032] The second voltage detection unit 52 is, for example, a comparator circuit, and detects a voltage applied from the power source 5 to the target system 10 via the fuse 25 and the switch 330. In addition, the second voltage detection unit 52 outputs a signal corresponding to the detected voltage to the acquisition unit 601.

[0033] The control unit 600 executes a program stored in the ROM in response to, for example, the on / off of the vehicle ignition. At this time, the control unit 600 controls the on / off of the drive unit 40. As a result, the control unit 600 controls the voltage applied to the coil 305, thereby controlling the on / off of the switch 330.

[0034] The acquisition unit 601 executes a program stored in the ROM, for example, in response to the on / off of the vehicle ignition. At this time, the acquisition unit 601 acquires from the first voltage detection unit 51 the voltage applied from the power source 5 to the coil 305 via the fuse 25. The acquisition unit 601 also acquires from the second voltage detection unit 52 the voltage applied from the power source 5 to the target system 10 via the fuse 25 and the switch 330.

[0035] The prediction unit 602 executes a program stored in the ROM in response to, for example, the on / off of the ignition of the vehicle. In this way, the prediction unit 602 predicts the life of the relay 30 based on the signals from the first voltage detection unit 51 and the second voltage detection unit 52 acquired by the acquisition unit 601.

[0036] As described above, vehicle system 1 is configured. Relay life prediction device 60 used in vehicle system 1 predicts the life of relay 30. Next, this life prediction will be described with reference to the time charts of Fig. 4, Fig. 7 to Fig. 9, and Fig. 5 and Fig. 6.

[0037] Here, in order to explain this life prediction, the following terms are defined. As shown in Fig. 1, the voltage applied from the power supply 5 to the coil 305 via the fuse 25 is defined as the coil voltage Vc. The voltage applied from the power supply 5 to the target system 10 via the fuse 25 and the switch 330 is defined as the target voltage Vsys.

[0038] During the period from time t0 to time t1, for example, the ignition of the vehicle is turned on. At this time, the control unit 600 of the relay life prediction device 60 switches the electric resistance for setting the current value of the constant current circuit of the drive unit 40 by, for example, controlling the on / off of the transistor of the constant current circuit of the drive unit 40. As a result, a current flows from the power source 5 to the ground 45 via the fuse 25, the first coil terminal 311, the coil 305, the second coil terminal 312, and the drive unit 40. At this time, the current flowing through the coil 305 gradually increases. In addition, since the current flows through the coil 305, the coil voltage Vc increases due to the electric resistance of the coil 305, and the coil 305 generates a magnetic field. Therefore, the core 315 generates a magnetic attraction force. However, since the elastic force of the leaf spring 334 is greater than the magnetic attraction force of the core 315, the movable contact 336 remains in contact with the stopper 340. Therefore, since the movable contact 336 and the fixed contact 338 are disconnected, the target voltage Vsys does not change.

[0039] Moreover, the acquisition unit 601 of the relay life prediction device 60 acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys is less than the voltage threshold Vsys_th, the prediction unit 602 of the relay life prediction device 60 determines that the relay 30 is turned off. Note that the voltage threshold Vsys_th is set by experiment, simulation, or the like so that the on / off of the relay 30 can be determined.

[0040] In the period from time t1 to time t2, the ignition of the vehicle is turned on. At this time, the control unit 600, for example, controls the on / off of a transistor in the constant current circuit of the drive unit 40 to switch an electric resistance for setting a current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that in the period from time t0 to time t1. Also, at this time, the magnetic attraction force of the core 315 becomes greater than the elastic force of the leaf spring 334, so that the armature plate 332 rotates and approaches the core 315. Therefore, the leaf spring 334 rotates together with the armature plate 332 in a direction approaching the core 315, and the movable contact 336 connected to the end of the leaf spring 334 approaches the fixed contact 338. As a result, the movable contact 336 and the fixed contact 338 are conductive, and a voltage is applied from the power source 5 to the target system 10 via the fuse 25, the first switch terminal 351, the fixed contact 338, the movable contact 336, the leaf spring 334, and the second switch terminal 352. This causes the target voltage Vsys to rise. However, since the target voltage Vsys is less than the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off.

[0041] Furthermore, since the absolute value of the increase in the current flowing through the coil 305 is smaller than that in the period from time t0 to time t1, the absolute value of the increase in the coil voltage Vc is smaller than that in the period from time t0 to time t1. This reduces the error in the operating voltage VS (to be described later) acquired by the acquisition unit 601.

[0042] At time t2, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t0 to time t1. Therefore, the error of the operating voltage VS, which will be described later, acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0043] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. Furthermore, at this time, the acquisition unit 601 acquires the coil voltage Vc from the first voltage detection unit 51. Furthermore, the prediction unit 602 determines whether the coil voltage Vc acquired by the acquisition unit 601 is an operating voltage VS and whether the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. As a result, the prediction unit 602 predicts the life of the relay 30. Here, the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Therefore, the prediction unit 602 determines that the relay 30 is normal. The first actuation threshold VS_th_low and the second actuation threshold VS_th_upp are set by experiment, simulation, or the like so as to determine that the relay 30 is normal. The second actuation threshold VS_th_upp is a value greater than the first actuation threshold VS_th_low.

[0044] In the period from time t2 to time t3, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that in the period from time t0 to time t1. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 is reduced. Also, at this time, as in the above, since the movable contact 336 is in contact with the fixed contact 338, a voltage is applied to the target system 10, and the target voltage Vsys increases to a constant value. Since the target voltage Vsys is greater than the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on.

[0045] In the period from time t3 to time t4, the ignition of the vehicle is turned on. At this time, the control unit 600 switches the electric resistance for setting the current value of the constant current circuit of the drive unit 40, for example, by controlling the on / off of the transistor of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes larger than that in the period from time t1 to time t3. At this time, as in the above, the movable contact 336 is in contact with the fixed contact 338, so that the target voltage Vsys is at a constant value. Since the target voltage Vsys is larger than the voltage threshold value Vsys_th, the prediction unit 602 determines that the relay 30 is turned on.

[0046] Furthermore, because the absolute value of the increase in the current flowing through the coil 305 is greater than in the period from time t1 to time t3, the absolute value of the increase in the coil voltage Vc is greater than in the period from time t1 to time t3, and the coil voltage Vc becomes a constant value Vc_C. Also, because the absolute value of the increase in the coil voltage Vc is greater than in the period from time t1 to time t3, the magnetic attraction force of the core 315 is likely to be greater, and the responsiveness of the switch 330 is higher than in the period from time t1 to time t3.

[0047] In the period from time t4 to time t5, the ignition of the vehicle is turned off. At this time, the control unit 600 switches the electric resistance for setting the current value of the constant current circuit of the drive unit 40, for example, by controlling the on / off of the transistor of the constant current circuit of the drive unit 40. As a result, the current flowing from the power source 5 to the ground 45 via the fuse 25, the first coil terminal 311, the coil 305, the second coil terminal 312, and the drive unit 40 becomes smaller than that at time t4. At this time, the current flowing through the coil 305 gradually decreases. In addition, since the current flowing through the coil 305 becomes smaller, the coil voltage Vc decreases. Therefore, the magnetic attraction force of the core 315 decreases. However, since the magnetic attraction force of the core 315 is larger than the elastic force of the leaf spring 334, the movable contact 336 and the fixed contact 338 remain in contact with each other. For this reason, the target voltage Vsys does not change. Moreover, since the target voltage Vsys is greater than the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on.

[0048] In the period from time t5 to time t6, the ignition of the vehicle is turned off. At this time, the control unit 600, for example, controls the on / off of a transistor in the constant current circuit of the drive unit 40 to switch an electric resistance for setting a current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that in the period from time t4 to time t5. Also, at this time, the elastic force of the leaf spring 334 becomes larger than the magnetic attraction force of the core 315, so that the armature plate 332 rotates and moves away from the core 315. Therefore, the leaf spring 334 rotates together with the armature plate 332 in a direction away from the core 315, so that the movable contact 336 connected to the end of the leaf spring 334 moves away from the fixed contact 338. As a result, the movable contact 336 and the fixed contact 338 are disconnected, and the target voltage Vsys decreases. However, since the target voltage Vsys is greater than the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on.

[0049] Furthermore, since the absolute value of the decrease in the current flowing through the coil 305 is smaller than that during the period from time t4 to time t5, the absolute value of the decrease in the coil voltage Vc is smaller than that during the period from time t4 to time t5. This reduces the error in the recovery voltage VR (to be described later) acquired by the acquisition unit 601.

[0050] At time t6, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t4 to time t5. Therefore, the error of the recovery voltage VR, which will be described later, acquired by the acquisition unit 601 becomes smaller. At this time, as in the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0051] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. Furthermore, the prediction unit 602 determines that the coil voltage Vc acquired by the acquisition unit 601 is a recovery voltage VR, and determines whether the recovery voltage VR is equal to or greater than the first recovery threshold VR_th_low and equal to or less than the second recovery threshold VR_th_upp. In this way, the prediction unit 602 predicts the life of the relay 30. Since the recovery voltage VR is equal to or greater than the first recovery threshold VR_th_low and equal to or less than the second recovery threshold VR_th_upp, the prediction unit 602 determines that the relay 30 is normal. The first return threshold VR_th_low and the second return threshold VR_th_upp are set by experiment, simulation, or the like so that the relay 30 is determined to be normal. The second return threshold VR_th_upp is a value larger than the first return threshold VR_th_low.

[0052] In the period from time t6 to time t7, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the amount of decrease in the current flowing through the coil 305 becomes smaller than that in the period from time t4 to time t5. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 is reduced. Also, at this time, as in the above, the movable contact 336 moves away from the fixed contact 338, so that the target voltage Vsys decreases and returns to the initial value. Since the target voltage Vsys is less than the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off.

[0053] In the period from time t7 to time t8, the ignition of the vehicle is turned off. At this time, the control unit 600, for example, controls the on / off of a transistor in the constant current circuit of the drive unit 40 to switch an electric resistance for setting a current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes larger than that in the period from time t5 to time t7. At this time, the movable contact 336 is separated from the fixed contact 338, so that the target voltage Vsys returns to the initial value. Since the target voltage Vsys is less than the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off.

[0054] Furthermore, because the absolute value of the decrease in the current flowing through the coil 305 is greater than in the period from time t5 to time t7, the absolute value of the decrease in the coil voltage Vc is greater than in the period from time t5 to time t7, and the coil voltage Vc returns to its initial value. Also, because the absolute value of the decrease in the coil voltage Vc is greater than in the period from time t5 to time t7, the magnetic attraction force of the core 315 tends to decrease, and the responsiveness of the switch 330 is higher than in the period from time t5 to time t7.

[0055] In the period from time t10 to time t12, the relay life prediction device 60 performs the same process as in the period from time t0 to time t2.

[0056] At time t12, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t10 to time t11. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0057] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Because the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is an operating voltage VS and whether the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Here, the operating voltage VS is greater than the second operating threshold VS_th_upp.

[0058] Here, as shown in FIG. 5, it is assumed that the movable contact 336 and the fixed contact 338 are worn due to aging of the relay 30. At this time, the size of the contact gap 350 increases, and the moving distance of the movable contact 336 until the movable contact 336 comes into contact with the fixed contact 338 becomes longer. Therefore, the magnetic attraction force of the core 315 required for the movable contact 336 to come into contact with the fixed contact 338 becomes larger than when the movable contact 336 and the fixed contact 338 are not worn. Therefore, at this time, the coil voltage Vc for the target voltage Vsys to rise and reach the voltage threshold Vsys_th becomes larger, and the operating voltage VS becomes larger than the second operating threshold VS_th_upp. In FIG. 5, the wear of the movable contact 336 and the fixed contact 338 is indicated by a dot pattern.

[0059] Therefore, in this case, because the actuation voltage VS is greater than the second actuation threshold VS_th_upp, the prediction unit 602 determines that there is a possibility that the movable contact 336 and the fixed contact 338 are worn, and thereby determines that the life of the relay 30 is short. In addition, since an abnormality due to a reason other than the life of the relay 30 is also possible, the prediction unit 602 determines that there is a possibility that the abnormality is due to a reason other than the life of the relay 30.

[0060] In the period from time t12 to time t16, the relay life predicting device 60 performs the same process as in the period from time t2 to time t6.

[0061] At time t16, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t14 to time t15. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0062] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR and whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. However, here, due to the process at time t12, the prediction unit 602 determines that the movable contact 336 and the fixed contact 338 may be worn, or that there may be an abnormality due to something other than the life of the relay 30.

[0063] In the period from time t16 to time t18, the relay life prediction device 60 performs the same process as in the period from time t6 to time t8. In addition, in the period from time t20 to time t22, the relay life prediction device 60 performs the same process as in the period from time t0 to time t2.

[0064] At time t22, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t20 to time t21. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0065] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Because the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines, using the coil voltage Vc acquired by the acquisition unit 601 as an operating voltage VS, whether or not the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Here, the operating voltage VS is less than the first operating threshold VS_th_low.

[0066] 6, it is assumed that a protrusion 360 is formed on the movable contact 336 and the fixed contact 338 due to aging of the relay 30. At this time, the size of the contact gap 350 is reduced, and the moving distance of the movable contact 336 until the movable contact 336 comes into contact with the fixed contact 338 is shortened. Therefore, the magnetic attraction force of the core 315 required for the movable contact 336 to come into contact with the fixed contact 338 is smaller than when the protrusion 360 is not formed on the movable contact 336 and the fixed contact 338. Therefore, at this time, the coil voltage Vc required for the target voltage Vsys to rise to the voltage threshold Vsys_th is reduced, and the operating voltage VS becomes less than the first operating threshold VS_th_low.

[0067] In addition, it is assumed here that the leaf spring 334 is deteriorated due to a decrease in the elastic constant and elastic force of the leaf spring 334 caused by aging deterioration of the relay 30. At this time, the magnetic attraction force of the core 315 tends to be greater than the elastic force of the leaf spring 334, so that the armature plate 332 tends to approach the core 315. Therefore, when the leaf spring 334 rotates together with the armature plate 332 in a direction approaching the core 315, the movable contact 336 connected to the end of the leaf spring 334 tends to approach the fixed contact 338. Therefore, the magnetic attraction force of the core 315 required for the movable contact 336 to come into contact with the fixed contact 338 becomes smaller than when the leaf spring 334 is not deteriorated. Therefore, at this time, the coil voltage Vc required for the target voltage Vsys to rise to the voltage threshold Vsys_th becomes smaller, so that the actuation voltage VS becomes less than the first actuation threshold VS_th_low.

[0068] Therefore, since the actuation voltage VS is less than the first actuation threshold VS_th_low, the prediction unit 602 determines that there is a possibility that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338, or that there is a possibility that the leaf spring 334 is deteriorated. As a result, the prediction unit 602 determines that the life of the relay 30 is short.

[0069] In the period from time t22 to time t26, the relay life predicting device 60 performs the same process as in the period from time t2 to time t6.

[0070] At time t26, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t24 to time t25. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0071] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR and whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. However, here, due to the process at time t22, the prediction unit 602 determines that the movable contact 336 and the fixed contact 338 may have a protrusion 360 formed thereon, or that the leaf spring 334 may have deteriorated.

[0072] In the period from time t26 to time t28, the relay life prediction device 60 performs the same process as in the period from time t6 to time t8. Next, as shown in the time chart of Fig. 7, in the period from time t30 to time t36, the relay life prediction device 60 performs the same process as in the period from time t0 to time t6.

[0073] At time t36, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t34 to time t35. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0074] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines that the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR, and determines whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is greater than the second return threshold VR_th_upp.

[0075] Here, as shown in FIG. 6, it is assumed that a protrusion 360 is formed on the movable contact 336 and the fixed contact 338 due to aging of the relay 30. At this time, the size of the contact gap 350 is reduced, so the moving distance of the movable contact 336 until it comes into contact with the fixed contact 338 is shortened. This also shortens the moving distance of the armature plate 332. Therefore, the size of the core plate gap 345 when the movable contact 336 is in contact with the fixed contact 338 is increased. Therefore, the distance between the core 315 and the armature plate 332 in the coil axis CL direction is increased, so that the magnetic attraction force of the core 315 acting on the armature plate 332 is reduced. Therefore, the elastic force of the leaf spring 334 is likely to be greater than the magnetic attraction force of the core 315, so that the armature plate 332 is likely to move away from the core 315. Therefore, when the leaf spring 334 rotates together with the armature plate 332 in a direction away from the core 315, the movable contact 336 connected to the end of the leaf spring 334 is more likely to separate from the fixed contact 338. At this time, the target voltage Vsys decreases and the coil voltage Vc required to reach the voltage threshold Vsys_th increases, so that the return voltage VR becomes greater than the second return threshold VR_th_upp.

[0076] Therefore, here, because the recovery voltage VR is greater than the second recovery threshold VR_th_upp, the prediction unit 602 determines that there is a possibility that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338, and thereby determines that the life of the relay 30 is short. In addition, at this time, since an abnormality of the relay 30 due to a reason other than the life of the relay 30 is also possible, the prediction unit 602 determines that there is a possibility of an abnormality due to a reason other than the life of the relay 30.

[0077] In the period from time t36 to time t38, the relay life prediction device 60 performs the same process as in the period from time t6 to time t8. In addition, in the period from time t40 to time t46, the relay life prediction device 60 performs the same process as in the period from time t0 to time t6.

[0078] At time t46, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t44 to time t45. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0079] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR and whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is less than the first return threshold VR_th_low.

[0080] Here, as shown in FIG. 5, it is assumed that the movable contact 336 and the fixed contact 338 are worn due to aging of the relay 30. At this time, the size of the contact gap 350 increases, so the moving distance of the movable contact 336 until it comes into contact with the fixed contact 338 increases. This also increases the moving distance of the armature plate 332. Therefore, the size of the core plate gap 345 when the movable contact 336 is in contact with the fixed contact 338 decreases. Therefore, the distance between the core 315 and the armature plate 332 in the coil axis CL direction decreases, so the magnetic attraction force of the core 315 acting on the armature plate 332 increases. Therefore, the elastic force of the leaf spring 334 is unlikely to become larger than the magnetic attraction force of the core 315, so the armature plate 332 is unlikely to separate from the core 315. Therefore, when the leaf spring 334 rotates together with the armature plate 332 in a direction away from the core 315, the movable contact 336 connected to the end of the leaf spring 334 is less likely to separate from the fixed contact 338. Therefore, at this time, the coil voltage Vc required for the target voltage Vsys to drop and reach the voltage threshold Vsys_th becomes smaller, and the return voltage VR becomes less than the first return threshold VR_th_low.

[0081] In addition, it is assumed here that the leaf spring 334 deteriorates due to a decrease in the elastic constant and elastic force of the leaf spring 334 caused by aging of the relay 30. At this time, the elastic force of the leaf spring 334 is unlikely to become greater than the magnetic attraction force of the core 315, so that the armature plate 332 is unlikely to separate from the core 315. Therefore, when the leaf spring 334 rotates together with the armature plate 332 in a direction away from the core 315, the movable contact 336 connected to the end of the leaf spring 334 is unlikely to separate from the fixed contact 338. Therefore, at this time, the coil voltage Vc required for the target voltage Vsys to decrease and reach the voltage threshold Vsys_th becomes small, so that the return voltage VR becomes less than the first return threshold VR_th_low.

[0082] Therefore, since the recovery voltage VR is less than the first recovery threshold VR_th_low, the prediction unit 602 determines that the movable contact 336 and the fixed contact 338 may be worn or that the leaf spring 334 may be deteriorated. As a result, the prediction unit 602 determines that the life of the relay 30 is short.

[0083] In the period from time t46 to time t48, relay life prediction device 60 performs the same process as in the period from time t6 to time t8. Next, as shown in the time chart of Fig. 8, in the period from time t50 to time t52, relay life prediction device 60 performs the same process as in the period from time t0 to time t2.

[0084] At time t52, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t50 to time t51. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0085] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Because the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is an operating voltage VS and whether the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Here, the operating voltage VS is greater than the second operating threshold VS_th_upp.

[0086] Because the actuation voltage VS is greater than the second actuation threshold VS_th_upp, the prediction unit 602 determines that there is a possibility that the movable contact 336 and the fixed contact 338 are worn out, or that there is a possibility that an abnormality has occurred due to a reason other than the life of the relay 30.

[0087] In the period from time t52 to time t56, the relay life predicting device 60 performs the same process as in the period from time t2 to time t6.

[0088] At time t56, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t54 to time t55. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, as in the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0089] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines that the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR, and determines whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is greater than the second return threshold VR_th_upp.

[0090] Since the recovery voltage VR is greater than the second recovery threshold VR_th_upp, it is possible that a protrusion 360 has been formed on the movable contact 336 and the fixed contact 338, or there is a possibility that an abnormality has occurred due to a reason other than the life of the relay 30. Furthermore, since the operating voltage VS is greater than the second operating threshold VS_th_upp at this time, it is possible that the movable contact 336 and the fixed contact 338 are worn out, or there is a possibility that an abnormality has occurred due to a reason other than the life of the relay 30. Therefore, at this time, it is highly likely that an abnormality has occurred due to a reason other than the life of the relay 30. Therefore, at this time, the prediction unit 602 determines that there is an abnormality due to a reason other than the life of the relay 30.

[0091] In the period from time t56 to time t58, the relay life prediction device 60 performs the same process as in the period from time t6 to time t8. In addition, in the period from time t60 to time t62, the relay life prediction device 60 performs the same process as in the period from time t0 to time t2.

[0092] At time t62, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t60 to time t61. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0093] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Because the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines, using the coil voltage Vc acquired by the acquisition unit 601 as an operating voltage VS, whether or not the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Here, the operating voltage VS is less than the first operating threshold VS_th_low.

[0094] Because the actuation voltage VS is less than the first actuation threshold VS_th_low, the prediction unit 602 determines that there is a possibility that a protrusion 360 has formed on the movable contact 336 and the fixed contact 338, or that there is a possibility that the leaf spring 334 has deteriorated.

[0095] In the period from time t62 to time t66, the relay life prediction device 60 performs the same process as in the period from time t2 to time t6.

[0096] At time t66, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t64 to time t65. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0097] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines that the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR, and determines whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is greater than the second return threshold VR_th_upp.

[0098] Since the recovery voltage VR is greater than the second recovery threshold VR_th_upp, there is a possibility that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338, or there is a possibility that an abnormality other than the life of the relay 30 exists. Also, since the operating voltage VS is less than the first operating threshold VS_th_low at this time, there is a possibility that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338, or there is a possibility that the leaf spring 334 has deteriorated. Therefore, at this time, there is a high probability that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338. Therefore, at this time, the prediction unit 602 determines that the life of the relay 30 is short by determining that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338.

[0099] In a period from time t66 to time t68, relay life prediction device 60 performs the same process as in the period from time t6 to time t8. Next, as shown in the time chart of Fig. 9, in a period from time t70 to time t72, relay life prediction device 60 performs the same process as in the period from time t0 to time t2.

[0100] At time t72, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t70 to time t71. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0101] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Because the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is an operating voltage VS and whether the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Here, the operating voltage VS is greater than the second operating threshold VS_th_upp.

[0102] Because the actuation voltage VS is greater than the second actuation threshold VS_th_upp, the prediction unit 602 determines that there is a possibility that the movable contact 336 and the fixed contact 338 are worn out, or that there is a possibility that an abnormality has occurred due to a reason other than the life of the relay 30.

[0103] In the period from time t72 to time t76, the relay life predicting device 60 performs the same process as in the period from time t2 to time t6.

[0104] At time t76, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t74 to time t75. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0105] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR and whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is less than the first return threshold VR_th_low.

[0106] Since the recovery voltage VR is less than the first recovery threshold VR_th_low, the movable contact 336 and the fixed contact 338 may be worn, or the leaf spring 334 may be deteriorated. Also, since the operating voltage VS is greater than the second operating threshold VS_th_upp at this time, the movable contact 336 and the fixed contact 338 may be worn, or there may be an abnormality due to a reason other than the life of the relay 30. Therefore, at this time, it is highly likely that the movable contact 336 and the fixed contact 338 are worn. Therefore, at this time, the prediction unit 602 determines that the movable contact 336 and the fixed contact 338 are worn, and thereby determines that the life of the relay 30 is short.

[0107] In the period from time t76 to time t78, the relay life prediction device 60 performs the same process as in the period from time t6 to time t8. In addition, in the period from time t80 to time t82, the relay life prediction device 60 performs the same process as in the period from time t0 to time t2.

[0108] At time t82, the ignition of the vehicle is turned on. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually increases, and the absolute value of the increase in the current flowing through the coil 305 becomes smaller than that during the period from time t80 to time t81. Therefore, the error of the operating voltage VS acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 approaches and comes into contact with the fixed contact 338, and the target voltage Vsys increases.

[0109] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Because the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned on. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines, using the coil voltage Vc acquired by the acquisition unit 601 as an operating voltage VS, whether or not the operating voltage VS is equal to or greater than the first operating threshold VS_th_low and equal to or less than the second operating threshold VS_th_upp. Here, the operating voltage VS is less than the first operating threshold VS_th_low.

[0110] Because the actuation voltage VS is less than the first actuation threshold VS_th_low, the prediction unit 602 determines that there is a possibility that a protrusion 360 has formed on the movable contact 336 and the fixed contact 338, or that there is a possibility that the leaf spring 334 has deteriorated.

[0111] In the period from time t82 to time t86, the relay life prediction device 60 performs the same process as in the period from time t2 to time t6.

[0112] At time t86, the ignition of the vehicle is turned off. At this time, the control unit 600 controls the on / off of the transistor of the constant current circuit of the drive unit 40, thereby switching the electric resistance for setting the current value of the constant current circuit of the drive unit 40. As a result, the current flowing through the coil 305 gradually decreases, and the absolute value of the decrease in the current flowing through the coil 305 becomes smaller than that during the period from time t84 to time t85. Therefore, the error of the recovery voltage VR acquired by the acquisition unit 601 becomes smaller. At this time, similarly to the above, the movable contact 336 moves away from the fixed contact 338, and the target voltage Vsys decreases.

[0113] The acquisition unit 601 also acquires the target voltage Vsys from the second voltage detection unit 52. Since the target voltage Vsys becomes the voltage threshold Vsys_th, the prediction unit 602 determines that the relay 30 is turned off. At this time, the acquisition unit 601 also acquires the coil voltage Vc from the first voltage detection unit 51. The prediction unit 602 also determines whether the coil voltage Vc acquired by the acquisition unit 601 is a return voltage VR and whether the return voltage VR is equal to or greater than the first return threshold VR_th_low and equal to or less than the second return threshold VR_th_upp. Here, the return voltage VR is less than the first return threshold VR_th_low.

[0114] Since the release voltage VR is less than the first release threshold VR_th_low, the movable contact 336 and the fixed contact 338 may be worn, or the leaf spring 334 may be deteriorated. Also, since the operating voltage VS is less than the first operating threshold VS_th_low at this time, the movable contact 336 and the fixed contact 338 may have a protrusion 360 formed thereon, or the leaf spring 334 may be deteriorated. Therefore, at this time, it is highly likely that the leaf spring 334 has deteriorated. Therefore, at this time, the prediction unit determines that the leaf spring 334 has deteriorated, and thereby determines that the life of the relay 30 is short.

[0115] In the period from time t86 to time t88, the relay life predicting device 60 performs the same process as in the period from time t6 to time t8.

[0116] As described above, the relay life prediction device 60 predicts the life of the relay 30. In this manner, the relay life prediction device 60 predicts the life of the relay 30 based on the change in the actuation voltage VS from when the relay 30 was normal, and the change in the release voltage VR from when the relay 30 was normal.

[0117] Specifically, the relay life prediction device 60 determines that the relay 30 is normal when the operating voltage VS is equal to or higher than the first operating threshold VS_th_low and equal to or lower than the second operating threshold VS_th_upp. Also, as shown in FIG. 10, the relay life prediction device 60 determines that an abnormality due to the life of the relay 30 exists when the operating voltage VS is lower than the first operating threshold VS_th_low. Furthermore, the relay life prediction device 60 determines that an abnormality due to the life of the relay 30 exists when the operating voltage VS is higher than the second operating threshold VS_th_upp. Note that in FIG. 10, when the operating voltage VS is lower than the first operating threshold VS_th_low, it is indicated as Low. Also, when the operating voltage VS is higher than the second operating threshold VS_th_upp, it is indicated as High.

[0118] Moreover, the relay life prediction device 60 determines that the relay 30 is normal when the recovery voltage VR is equal to or greater than the first recovery threshold VR_th_low and equal to or less than the second recovery threshold VR_th_upp. Furthermore, the relay life prediction device 60 determines that an abnormality due to the life of the relay 30 exists when the recovery voltage VR is less than the first recovery threshold VR_th_low. Furthermore, the relay life prediction device 60 determines that an abnormality due to the life of the relay 30 exists when the recovery voltage VR is greater than the second recovery threshold VR_th_upp. Note that in FIG. 10, when the recovery voltage VR is less than the first recovery threshold VR_th_low, it is indicated as Low. Furthermore, when the recovery voltage VR is greater than the second recovery threshold VR_th_upp, it is indicated as High.

[0119] Furthermore, when the operating voltage VS is greater than the second operating threshold VS_th_upp and the return voltage VR is less than the first return threshold VR_th_low, the relay life predicting device 60 determines that the movable contact 336 and the fixed contact 338 are worn. When the operating voltage VS is less than the first operating threshold VS_th_low and the return voltage VR is greater than the second return threshold VR_th_upp, the relay life predicting device 60 determines that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338. When the operating voltage VS is less than the first operating threshold VS_th_low and the return voltage VR is less than the first return threshold VR_th_low, the relay life predicting device 60 determines that the leaf spring 334 is deteriorated. As a result, the relay life predicting device 60 determines that the lives of the movable contact 336, the fixed contact 338 and the leaf spring 334 are short, and thereby determines that the life of the relay 30 is short.

[0120] Furthermore, the relay life predicting device 60 of this embodiment also provides the following effects.

[0121] Here, the coil voltage Vc changes even while the acquisition unit 601 of the relay life prediction device 60 acquires the operating voltage VS and the recovery voltage VR. Therefore, an error occurs in the operating voltage VS and the recovery voltage VR acquired by the acquisition unit 601. In response to this, the control unit 600 of the relay life prediction device 60 makes the change in the coil voltage Vc when the target voltage Vsys becomes the voltage threshold Vsys_th smaller than when the target voltage Vsys is not the voltage threshold Vsys_th. As a result, when the acquisition unit 601 acquires the operating voltage VS and the recovery voltage VR, the change in the coil voltage Vc becomes smaller, and therefore the error in the operating voltage VS and the recovery voltage VR acquired by the acquisition unit 601 becomes smaller.

[0122] (Other embodiments) The present disclosure is not limited to the above-described embodiments, and appropriate modifications can be made to the above-described embodiments. Furthermore, in each of the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are particularly clearly stated as essential or where they are clearly considered essential in principle.

[0123] The control unit, acquisition unit, prediction unit, and method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit, acquisition unit, prediction unit, and method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit, acquisition unit, prediction unit, and method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0124] In the above embodiment, the driving unit 40 is a constant current circuit, but is not limited to this and may be a constant voltage circuit constituted by an electric resistor, a transistor, a Zener diode, and the like.

[0125] In the above embodiment, the first voltage detection unit 51 and the second voltage detection unit 52 are comparator circuits, but are not limited to this and may be, for example, an A / D converter or the like.

[0126] In the above embodiment, the prediction unit 602 of the relay life prediction device 60 predicts the life of the relay 30 based on the operating voltage VS, the first operating threshold VS_th_low, and the second operating threshold VS_th_upp. Without being limited to this, the prediction unit 602 may predict the life of the relay 30 based on the amount of change in the operating voltage VS from when the relay 30 is normal. For example, the prediction unit 602 calculates the amount of change in the operating voltage VS by subtracting the operating voltage VS when the relay 30 is normal from the operating voltage VS acquired by the acquisition unit 601. Note that the operating voltage VS when the relay 30 is normal may be replaced with a predetermined value set by an experiment, a simulation, or the like.

[0127] Furthermore, the prediction unit 602 determines that the relay 30 is normal when the amount of change in the operating voltage VS is equal to or greater than the first change threshold and equal to or less than the second change threshold. The first change threshold and the second change threshold are set by experiment, simulation, or the like so that the relay 30 is determined to be normal. The first change threshold is a negative value. The second change threshold is a positive value.

[0128] Moreover, when the amount of change in the operating voltage Vs is less than the first change threshold, the prediction unit 602 determines that there is an abnormality due to the life of the relay 30. Furthermore, when the amount of change in the operating voltage Vs is greater than the second change threshold, the prediction unit 602 determines that there is an abnormality due to the life of the relay 30.

[0129] Furthermore, the prediction unit 602 predicts the life of the relay 30 based on the return voltage VR, the first return threshold VR_th_low, and the second return threshold VR_th_upp. Without being limited thereto, the prediction unit 602 may predict the life of the relay 30 based on the amount of change in the return voltage VR from when the relay 30 was normal. For example, the prediction unit 602 calculates the amount of change in the return voltage VR by subtracting the return voltage VR when the relay 30 was normal from the return voltage VR acquired by the acquisition unit 601. Note that the return voltage VR when the relay 30 was normal may be replaced with a predetermined value set by an experiment, a simulation, or the like.

[0130] Furthermore, when the change amount of the recovery voltage VR is equal to or greater than the third change threshold and equal to or less than the fourth change threshold, the prediction unit 602 determines that the relay 30 is normal. The third change threshold and the fourth change threshold are set by experiment, simulation, or the like so that the relay 30 is determined to be normal. The third change threshold is a negative value. The fourth change threshold is a positive value.

[0131] Moreover, when the amount of change in the recovery voltage VR is less than the third change threshold, the prediction unit 602 determines that there is an abnormality due to the life of the relay 30. Furthermore, when the amount of change in the recovery voltage VR is greater than the fourth change threshold, the prediction unit 602 determines that there is an abnormality due to the life of the relay 30.

[0132] Furthermore, when the change in the operating voltage VS is greater than the second change threshold and the change in the release voltage VR is less than the third change threshold, the prediction unit 602 determines that the movable contact 336 and the fixed contact 338 are worn. Furthermore, when the change in the operating voltage VS is less than the first change threshold and the change in the release voltage VR is greater than the fourth change threshold, the prediction unit 602 determines that the protrusion 360 is formed on the movable contact 336 and the fixed contact 338. Furthermore, when the change in the operating voltage VS is less than the first change threshold and the change in the release voltage VR is less than the third change threshold, the prediction unit 602 determines that the leaf spring 334 is deteriorated. As a result, the relay life prediction device 60 determines that the life of the movable contact 336, the fixed contact 338, and the leaf spring 334 is short, and thereby determines that the life of the relay 30 is short.

[0133] Furthermore, the prediction unit 602 may determine whether the relay 30 is normal or not when the conditions of the above-mentioned operating voltage VS and release voltage VR are met a predetermined number of times or more. In this way, when the conditions of the above-mentioned operating voltage VS and release voltage VR are met instantaneously, it is not determined that there is an abnormality due to the life of the relay 30, and thus erroneous determination by the prediction unit 602 is suppressed.

[0134] Furthermore, as described above, when the acquisition unit 601 acquires the operating voltage VS and the recovery voltage VR, the coil voltage Vc changes, and therefore an error occurs in the operating voltage VS and the recovery voltage VR acquired by the acquisition unit 601. In response to this, the prediction unit 602 may correct the operating voltage VS by subtracting a predetermined value from the operating voltage VS acquired by the acquisition unit 601. This reduces the error in the operating voltage VS acquired by the acquisition unit 601. The prediction unit 602 may also correct the recovery voltage VR by adding a predetermined value to the recovery voltage VR acquired by the acquisition unit 601. This reduces the error in the recovery voltage VR acquired by the acquisition unit 601. The predetermined value for this correction is set by experiment, simulation, or the like so that the error in the operating voltage VS and the recovery voltage VR is reduced. [Explanation of symbols]

[0135] 20 Relay life prediction system 30 Relay 305 Coil 330 Switch 40 Drive unit 60 Relay life prediction device

Claims

1. an acquisition unit (601) that acquires a value related to a target voltage (Vsys), which is a voltage applied to an object (10) from a relay (30) having a coil (305) and a switch (330) that applies a voltage to the object (10) when the relay (30) is turned on by an electromagnetic force caused by a current flowing through the coil, and a value related to an operating voltage (VS), which is a voltage (Vc) of the coil when the target voltage increases and reaches a voltage threshold (Vsys_th) when the switch is turned on from off; A prediction unit (602) for predicting a lifespan of the relay based on a change in the operating voltage from when the relay is normal; A relay life prediction device comprising:

2. The prediction unit is When the tripping voltage is equal to or higher than a first tripping threshold (VS_th_low) and equal to or lower than a second tripping threshold (VS_th_upp) that is higher than the first tripping threshold, the relay is determined to be normal; When the actuation voltage is less than the first actuation threshold value, it is determined that an abnormality due to the life of the relay exists; The relay life prediction device according to claim 1 , wherein when the actuation voltage is greater than the second actuation threshold value, it is determined that an abnormality due to the life of the relay exists.

3. The prediction unit is determining that the relay is normal when an amount of change in the operating voltage from when the relay is normal is equal to or greater than a first change threshold and equal to or less than a second change threshold that is greater than the first change threshold; When the amount of change in the operating voltage from when the relay was normal is less than the first change threshold, it is determined that an abnormality has occurred due to the life of the relay; 3. The relay life prediction device according to claim 1, further comprising: a determination unit configured to determine that an abnormality due to the life of the relay exists when an amount of change in the operating voltage from when the relay is normal is greater than the second change threshold value.

4. an acquisition unit (601) that acquires a value related to a target voltage (Vsys), which is a voltage applied to an object (10) from a relay (30) having a coil (305) and a switch (330) that applies a voltage to the object (10) when the relay (30) is turned on by an electromagnetic force caused by a current flowing through the coil, and a value related to a recovery voltage (VR), which is a voltage (Vc) of the coil when the target voltage drops to a voltage threshold (Vsys_th) when the switch is turned off from on; A prediction unit (602) for predicting the life of the relay based on a change in the release voltage from when the relay is normal; A relay life prediction device comprising:

5. The prediction unit is When the recovery voltage is equal to or higher than a first recovery threshold (VR_th_low) and equal to or lower than a second recovery threshold (VR_th_upp) that is higher than the first recovery threshold, the relay is determined to be normal; When the recovery voltage is less than the first recovery threshold, it is determined that an abnormality due to the life of the relay exists; The relay life prediction device according to claim 4 , wherein when the release voltage is greater than the second release threshold value, it is determined that an abnormality due to the life of the relay exists.

6. The prediction unit is determining that the relay is normal when an amount of change in the release voltage from when the relay is normal is equal to or greater than a first change threshold and equal to or less than a second change threshold that is greater than the first change threshold; When the amount of change in the release voltage from when the relay is normal is less than the first change threshold, it is determined that an abnormality occurs due to the life of the relay; 6. The relay life prediction device according to claim 4, wherein when an amount of change in the release voltage from when the relay is normal is greater than the second change threshold, it is determined that an abnormality due to the life of the relay exists.

7. The switch includes a fixed portion (338), a movable portion (336) that moves due to an electromagnetic force generated by a current flowing through the coil and contacts the fixed portion to apply a voltage to the object, and an elastic member (334) that applies a force to the movable portion in a direction in which the movable portion moves away from the fixed portion, 7. The relay life prediction device according to claim 1, wherein the prediction unit predicts the lives of the fixed portion, the movable portion, and the elastic member.

8. 8. The relay life prediction device according to claim 1, further comprising a control unit (600) that causes a change in the coil voltage (Vc) when the target voltage becomes the voltage threshold value to be smaller than a change in the coil voltage (Vc) when the target voltage is not the voltage threshold value.

9. A relay (30) having a coil (305) and a switch (330) that applies a voltage to an object (10) when turned on by an electromagnetic force caused by a current flowing through the coil; a relay life prediction device (60) including: an acquisition unit (601) that acquires a value related to a target voltage (Vsys) that is a voltage applied from the relay to the target object; and a value related to an operating voltage (VS) that is a voltage (Vc) of the coil when the target voltage increases and reaches a voltage threshold (Vsys_th) when the switch is turned on from off; and a prediction unit (602) that predicts a life of the relay based on a change in the operating voltage from when the relay is normal; A relay life prediction system comprising:

10. A relay (30) having a coil (305) and a switch (330) that applies a voltage to an object (10) when turned on by an electromagnetic force caused by a current flowing through the coil; a relay life prediction device (60) including: an acquisition unit (601) that acquires a value related to a target voltage (Vsys) that is a voltage applied from the relay to the target object; and a value related to a return voltage (VR) that is a voltage (Vc) of the coil when the target voltage drops to a voltage threshold (Vsys_th) when the switch is turned from on to off; and a prediction unit (602) that predicts the life of the relay based on a change in the return voltage from when the relay is normal; A relay life prediction system comprising:

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