Vehicle shutoff device

Abstract

Provided is a shut-off device for a vehicle, the device being capable of operating so as to further draw out the durability performance of a switch.　The shut-off device (1) comprises a first switch (33A) that switches an electrical power path (11), which is a route for transmitting electrical power based on a power supply unit (10), between a conductive state and a shut-off state. The shut-off device (1) comprises a control unit (15) that executes a degradation determination process for comparing a resistance value (R) of the first switch (33A) with a resistance threshold value (Th1). When the resistance value (R) is greater than or equal to the resistance threshold value (Th1), the control unit (15) determines that the first switch (33A) is in a degraded state, and sends a notification of the degraded state to the outside.

Description

[Technical Field]

[0001] The present disclosure relates to a shutoff device for a vehicle. [Background technology]

[0002] Patent Document 1 discloses a power supply device that supplies power stored in a battery to a load by controlling the on / off of a semiconductor switch using a semiconductor switch drive unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-188983 [Patent Document 2] Japanese Patent Application Publication No. 2017-225307 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-11040 Summary of the Invention [Problem to be solved by the invention]

[0004] As power sources become increasingly powerful, the current flowing through the power path from the power source to the load increases. This increases the burden on switches and circuit breakers in the power path, raising concerns that their contacts may become more susceptible to wear. For this reason, there is a growing need to determine whether the contacts of switches and circuit breakers have become worn and to operate them based on the results of this determination. One known method involves determining whether a switch or circuit breaker satisfies its required performance by predetermining an upper limit on the number of times the switch or circuit breaker can be opened and closed, and comparing the number of times with the upper limit. However, this method may result in a situation where the switch or circuit breaker no longer satisfies the required performance when the number of times reaches the upper limit, even though the contacts of the switch or circuit breaker are not worn and still meet the required performance (i.e., are still usable). Therefore, a method for operating switches and circuit breakers while further enhancing their durability is desired.

[0005] The present disclosure has been made in light of the above-mentioned circumstances, and aims to provide a vehicle circuit breaking device that can be operated in a manner that further enhances the durability performance of the switch. [Means for solving the problem]

[0006] The vehicle shutoff device of the present disclosure comprises: A vehicle shutoff device having a switch that switches a power path, which is a path for transmitting power from a power supply unit, between a conductive state and a cutoff state, a control unit that executes a deterioration determination process that compares the resistance value of the switch with a resistance threshold value; When the resistance value is equal to or greater than the resistance threshold value, the control unit determines that the switch is in a deteriorated state and notifies an external device that the switch is in the deteriorated state. [Effects of the Invention]

[0007] According to the present disclosure, the switch can be operated in a manner that further enhances its durability performance. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram illustrating a vehicle power supply system including a vehicle breaker device according to a first embodiment. [Figure 2] FIG. 2 is a flowchart illustrating an example of control by the control unit in the vehicle blocking device of the first embodiment. [Figure 3] FIG. 3 is a graph showing the change over time in the resistance value of the first switch. [Figure 4] FIG. 4 is a circuit diagram showing the connection position of a voltage detection unit to a low-potential side power path in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] The vehicle shutoff device of the present disclosure comprises: [1] A circuit breaker for a vehicle having a switch that switches a power path, which is a path for transmitting power from a power supply unit, between a conductive state and a cut-off state. The circuit breaker has a control unit that executes a deterioration determination process that compares the resistance value of the switch with a resistance threshold value. If the resistance value is equal to or greater than the resistance threshold value, the control unit determines that the switch is in a deteriorated state and notifies the outside that the switch is in a deteriorated state.

[0011] In the vehicle circuit breaker described in [1] above, the resistance value of the switch can be used as an index for estimating the condition of the switch. Therefore, it is possible to determine whether the switch is in a deteriorated state based on the condition of the switch itself, making it easier to maximize the durability of the switch. Furthermore, since the deteriorated state is notified to the outside, it is easy to take external measures based on the condition of the switch. Here, a deteriorated state refers to a state in which the switch has deteriorated compared to when it was first installed in the circuit breaker, and its ability to switch the power path between a conductive state and a cut-off state has deteriorated.

[0012] [2] In the vehicle circuit breaker described above in [1], the resistance value may be based on the potential difference across the switch when the switch is in the on state and current flows through the power path, and the current flowing through the power path.

[0013] The vehicle circuit breaker described in [2] above is configured to determine that the switch is in a deteriorated state if the resistance value based on the potential difference across the switch and the current flowing in the power path when the switch is in the on state and current is flowing in the power path is equal to or greater than a threshold value. Therefore, it is possible to determine whether the switch is in a deteriorated state in accordance with the state of the switch itself, and to operate the switch in a manner that further maximizes its durability.

[0014] [3] The vehicle circuit breaker device of [2] above may further include a second switch that switches the power path between a conductive state and a cutoff state. The circuit breaker may be configured to perform switching control to switch the second switch from an off state to an on state after the second switch, thereby causing the power path to start conducting or a current increase. The control unit may perform a degradation determination process that compares the resistance value when the switching control is performed with a resistance threshold.

[0015] In the vehicle circuit breaker described in [3] above, in the switching control, the first switch is switched to the on state later than the second switch, so that an inrush current is likely to flow through the switch. As a result, the contacts of the switch are likely to wear (deteriorate). With this configuration, it is possible to determine the deterioration of the switch in the switching control in which the contacts of the switch are likely to wear.

[0016] [4] In the vehicle circuit breaker of [3] above, the power path may include a high-potential side power path and a low-potential side power path having a lower potential than the high-potential side power path. A second switch may be provided on one of the high-potential side power path and the low-potential side power path, and a switch may be provided on the other. The circuit breaker may further include a resistor and a third switch connected in series to the resistor, and a parallel switching path may be provided in which the resistor and the third switch are connected in parallel to the switch. The switching control may be control to start energizing the power path by turning the second switch and the third switch on while keeping the switch off.

[0017] In the vehicle circuit breaker described in [4] above, when the second and third switches are turned on to energize the power path in advance, the resistor prevents the peak of the current flowing through the third switch from becoming too large, allowing current to flow through the power path. After that, the switch is switched on while maintaining the second switch in the on state, thereby suppressing the peak of the inrush current flowing through the switch.

[0018] [5] In the vehicle circuit breaker of [4] above, the control unit can detect the voltage between both terminals of the switch.

[0019] The vehicle circuit breaking device described above in [5] can detect the resistance value of the target switch more accurately.

[0020] [6] In any of the above-mentioned vehicle circuit breaking devices [2] to [5], the control unit may execute a deterioration determination process that compares the resistance value when the magnitude of the current flowing through the power path is equal to or greater than the current threshold value with the resistance threshold value.

[0021] The vehicle circuit breaking device described above in [6] is configured to compare the current flowing in the power line with a current threshold value, so that, for example, the current state used when detecting the resistance value can be narrowed down to a state appropriate for detecting the resistance value, thereby increasing the reliability of the calculated resistance value.

[0022] <Embodiment 1> [Configuration of the circuit breaker] 1 is a power supply system mounted on a vehicle, and includes a power supply unit 10 and a circuit breaker 1. The circuit breaker 1 has a power path 11, a system main relay 33, a current detection unit 38, a voltage detection unit 39, and a control unit 15. The vehicle power supply system 100 is configured to be able to supply power from the power supply unit 10 to the load 35 via the power path 11, which is a path along which power is transmitted between the power supply unit 10 and the load 35.

[0023] The power supply unit 10 is a battery capable of supplying power to the load 35. The power supply unit 10 may be, for example, a lead battery or a battery pack configured by combining a plurality of unit cells, such as lithium ion batteries or nickel-metal hydride batteries, in series.

[0024] The power path 11 includes a high-potential side power path 17 and a low-potential side power path 20. The high-potential side power path 17 is electrically connected to the high-potential side terminal of the power supply unit 10. The output voltage of the power supply unit 10 is applied to the high-potential side power path 17. The low-potential side power path 20 is electrically connected to the low-potential side terminal of the power supply unit 10. The low-potential side power path 20 has a lower potential than the high-potential side power path 17. The output voltage of the power supply unit 10 corresponds to the potential difference between the high-potential side terminal and the low-potential side terminal. The power path 11 is a path for transmitting power from the power supply unit 10 to the load 35. A fuse F is interposed in the high-potential side power path 17. The fuse F cuts off the current flowing through the high-potential side power path 17 when excessive current flows through the high-potential side power path 17.

[0025] In the present disclosure, "electrically connected" preferably means a configuration in which the connection objects are connected in a mutually conductive state (a state in which a current can flow) so that the potentials of both connection objects are equal. However, this configuration is not limited to this. For example, "electrically connected" may also mean a configuration in which the connection objects are connected in a state in which the two connection objects can be electrically connected with an electrical component interposed between them.

[0026] A load 35 is electrically connected to the high-potential side power path 17 and the low-potential side power path 20. The load 35 is an in-vehicle electronic component, and is applicable to products such as electric components, ECUs, and ADAS target components. The current output from the high-potential side terminal of the power supply unit 10 flows in the following order: high-potential side power path 17, load 35, low-potential side power path 20, and low-potential side terminal of the power supply unit 10.

[0027] The system main relay 33 is provided between the power supply unit 10 and the load 35, interposed between the high-potential-side power path 17 and the low-potential-side power path 20. The system main relay 33 has a first switch 33A, a second switch 33B, and a parallel switching path 33C, which are switches. The first switch 33A and the second switch 33B are, for example, relay switches having internal contacts that physically switch between a contacted state and a separated state. The parallel switching path 33C has a resistor 33D and a third switch 33E connected in series to the resistor 33D. The third switch 33E is a relay switch having a configuration similar to that of the first switch 33A and the second switch 33B. The third switch 33E is a so-called precharge relay.

[0028] The first switch 33A is provided on the low-potential side power path 20. The second switch 33B is provided on the high-potential side power path 17 on the opposite side of the power supply unit 10, with a fuse F in between. The resistor 33D and the third switch 33E of the parallel switching path 33C are electrically connected to the low-potential side power path 20 so as to be in parallel with the first switch 33A. The first switch 33A, the second switch 33B, and the third switch 33E are controlled by a predetermined control device C (hereinafter simply referred to as the control device C) to switch between an ON state and an OFF state. The first switch 33A, the second switch 33B, and the third switch 33E switch the power path 11 between a conductive state and a cut-off state by switching between an ON state and an OFF state.

[0029] The current detection unit 38 is provided in the low-potential side power path 20 closer to the power supply unit 10 than the first switch 33A. The current detection unit 38 has, for example, a resistor and a differential amplifier, and is configured to be able to output a value indicating the current flowing through the low-potential side power path 20 (specifically, an analog voltage corresponding to the value of the current flowing through the low-potential side power path 20) as a current value A. In other words, the current detection unit 38 detects the current state of the current flowing through the power path 11 as a current value A.

[0030] The voltage detection unit 39 is configured as, for example, a voltage detection circuit, and is configured to be able to output a voltage value V corresponding to the potential difference between the terminal of the first switch 33A on the power supply unit 10 side and the terminal on the load 35 side. That is, the voltage detection unit 39 detects the voltage state of the voltage in the power path 11 as the voltage value V. In other words, the voltage detection unit 39 detects the potential difference between the terminals of the first switch 33A on both the power supply unit 10 side and the load 35 side (the terminals on both the side where power is supplied to the first switch 33A and the side where power is output) as the voltage value V.

[0031] The control unit 15 is configured as, for example, a microcomputer and includes a CPU and a storage unit 15D configured with a ROM, a RAM, a non-volatile memory, etc. The control unit 15 includes a resistance value calculation unit 15A, a deterioration detection unit 15B, and a notification function unit 15C. The resistance value calculation unit 15A is configured to receive a current value A and a voltage value V from a current detection unit 38 and a voltage detection unit 39, respectively, and calculates and detects a resistance value R based on these values. For example, the resistance value R is calculated by dividing the voltage value V by the current value A. The control unit 15 detects the voltage between both terminals of the first switch 33A based on the voltage value V from the voltage detection unit 39.

[0032] The deterioration detection unit 15B is configured to execute a deterioration determination process that compares the resistance value R calculated by the resistance value calculation unit 15A with a resistance threshold value Th1 stored in the memory unit 15D of the control unit 15. The deterioration detection unit 15B is configured to output a deterioration signal Sd when it determines in the deterioration determination process that the resistance value R is equal to or greater than the resistance threshold value Th1. The deterioration signal Sd is output when the first switch 33A is in a deteriorated state. That is, the control unit 15 determines that the first switch 33A is in a deteriorated state when the resistance value R is equal to or greater than the resistance threshold value Th1. When the deterioration detection unit 15B determines in the deterioration determination process that the resistance value R is smaller than the resistance threshold value Th1, it does not output the deterioration signal Sd. In this case, the control unit 15 determines that the first switch 33A is not in a deteriorated state.

[0033] The notification function unit 15C is configured, for example, by a communication device, and is configured to notify by sending information to an external device (not shown) such as a BMS (battery management system) based on the input of the deterioration signal Sd from the deterioration detection unit 15B.

[0034] [Regarding control in the control unit] Next, an example of control executed by the control unit 15 will be described with reference to Fig. 2 etc. For example, in a vehicle equipped with the vehicle power supply system 100, when the ignition switch is off, the first switch 33A and second switch 33B of the system main relay 33 and the third switch 33E of the parallel switching path 33C are maintained in an off state. At this time, the power path 11 is in a cutoff state in which the supply of power from the power supply unit 10 to the load 35 is cut off.

[0035] From this state, first, step S1 is executed to switch the ignition switch from off to on. Next, when the process proceeds to step S2, an on signal Son (see FIG. 1) is output from the control device C, and switching control is executed in which the first contactor 33A, the second contactor 33B, and the third contactor 33E are switched from off to on based on the on signal Son. Specifically, in the switching control, the second contactor 33B, the third contactor 33E, and the first contactor 33A are switched from off to on in this order based on the on signal Son output from the control device C. In other words, the switching control is a control in which the first contactor 33A is turned off while the second contactor 33B and the third contactor 33E are turned on to start energizing the power path 11, and then the first contactor 33A is turned on while the second contactor 33B and the third contactor 33E are maintained in the on state. That is, the first switch 33A switches from the OFF state to the ON state after the second switch 33B. The timing at which the control device C outputs the ON signal Son to each switch can be varied in various ways. That is, the control device C can perform control different from the switching control.

[0036] For example, by shifting the timing at which the control device C outputs the on signal Son to each of the second switch 33B, the third switch 33E, and the first switch 33A, the timing at which the second switch 33B, the third switch 33E, and the first switch 33A switch to the on state can be shifted. Note that when the second switch 33B and the third switch 33E are switched to the on state, current begins to flow through the power path 11. Because the resistor 33D is connected in series with the third switch 33E, current begins to flow slowly through the power path 11 so that it gradually increases.

[0037] Furthermore, when the first switch 33A is switched to the ON state, the power path 11 enters a conductive state that allows power to be supplied from the power supply unit 10 to the load 35. When the first switch 33A is switched to the ON state, an inrush current immediately flows through the first switch 33A. At this time, a current rise occurs, in which the current value A flowing through the power path 11 rises sharply. In this way, switching control is executed, and the power path 11 begins to conduct or a current rise occurs. The inrush current continues to flow for a predetermined short time after the first switch 33A is switched to the ON state, and after the predetermined short time has elapsed, the current flowing through the first switch 33A settles so as to remain within a predetermined range that is smaller than the magnitude of the inrush current. In this way, the first switch 33A enters the ON state, and a current flows through the power path 11.

[0038] Then, when the process proceeds to step S3, the control unit 15 determines whether a predetermined short time has elapsed since the power path 11 was switched to the conductive state (when the first switch 33A was switched to the on state). For example, the control unit 15 is equipped with a timer function and is configured to be able to measure the predetermined short time since the power path 11 was switched to the conductive state. Whether the power path 11 has switched to the conductive state can be determined, for example, based on the degree to which the value of current value A changes within a predetermined time (the amount of change in current value A per unit time). If the control unit 15 determines in step S3 that the predetermined short time has not elapsed since the power path 11 was switched to the conductive state (No in step S3), the process of step S3 is repeated.

[0039] Then, in step S3, if the control unit 15 determines that a predetermined short time has elapsed since the power path 11 was switched to the conductive state (Yes in step S3), the process proceeds to step S4. In step S4, the control unit 15 determines whether the magnitude of the current value A remains within a predetermined range. For example, the control unit 15 is configured to compare the current value A input from the current detection unit 38 with a current threshold Th2 stored in the memory unit 15D of the control unit 15 and an upper current threshold Th3 that is greater than the current threshold Th2. For example, the control unit 15 is configured to use its own timer function to determine whether the state in which the magnitude of the current value A is greater than or equal to the current threshold Th2 and less than the upper current threshold Th3 has continued for a predetermined time (i.e., whether fluctuations in the current flowing through the power path 11 have settled down). In step S4, if the control unit 15 determines that the state in which the magnitude of the current value A is equal to or greater than the current threshold Th2 and smaller than the upper limit current threshold Th3 has not continued for a predetermined time (No in step S4), the processing of step S4 is repeated.

[0040] In step S4, if control unit 15 determines that the state in which current value A is equal to or greater than current threshold value Th2 and smaller than upper current threshold value Th3 has continued for a predetermined time (Yes in step S4), control unit 15 proceeds to step S5. In step S5, control unit 15 obtains resistance value R in resistance value calculation unit 15A based on current value A and voltage value V input from current detection unit 38 and voltage detection unit 39, respectively. In other words, control unit 15 detects resistance value R when current value A flowing through power path 11 is equal to or greater than current threshold value Th2. Then, control unit 15 proceeds to step S6.

[0041] When the process proceeds to step S6, the control unit 15 executes a deterioration determination process in which the deterioration detection unit 15B compares the resistance value R with the resistance threshold value Th1. The control unit 15 executes the deterioration determination process in which the resistance value R when switching control is executed by the control device C is compared with the resistance threshold value Th1. For example, in the deterioration determination process, if it is determined that the resistance value R is equal to or greater than the resistance threshold value Th1 (Yes in step S6), the process proceeds to step S7, and the deterioration detection unit 15B outputs a deterioration signal Sd.

[0042] On the other hand, if the control unit 15 determines in the deterioration determination process that the resistance value R is smaller than the resistance threshold value Th1 (No in step S6), it does not output the deterioration signal Sd. In this way, the control unit 15 executes the deterioration determination process of comparing the resistance value R when the magnitude of the current flowing through the power path 11 is equal to or greater than the current threshold value Th2 with the resistance threshold value Th1. In other words, the control unit 15 executes the deterioration determination process of determining the degree of deterioration of the first switch 33A by comparing the resistance value R of the first switch 33A, which is based on the voltage value V (potential difference) across the first switch 33A when the first switch 33A is in the on state and a current flows through the power path 11, and the current value A flowing through the power path 11, with the resistance threshold value Th1.

[0043] Next, when the deterioration signal Sd is input to the notification function unit 15C, the notification function unit 15C transmits information to an external device (not shown). That is, the notification function unit 15C of the control unit 15 notifies the outside that it is in a deteriorated state. In this way, the process shown in FIG. 2 ends.

[0044] As the switching control by the control device C is repeated, the number of times the first switch 33A is switched to the on state increases. Accordingly, wear and oxidation of the contacts in the first switch 33A progresses, and the resistance value R of the first switch 33A gradually increases. The control unit 15 determines the degree of deterioration of the first switch 33A by comparing the resistance value R, which gradually increases as the number of times the first switch 33A is switched to the on state, with the resistance threshold value Th1.

[0045] For example, when a large inrush current flows frequently through the first switch 33A, the rate of increase over time in the resistance value R of the first switch 33A becomes larger, as indicated by the line S1 in FIG. 3. In contrast, when a large inrush current flows infrequently through the first switch 33A, the rate of increase over time in the resistance value R of the first switch 33A becomes smaller, as indicated by the line S2. When a large inrush current flows frequently through the first switch 33A (the line S1), the time at which the resistance value R reaches the resistance threshold value Th1 is T1. When a large inrush current flows infrequently through the first switch 33A (the line S2), the time at which the resistance value R reaches the resistance threshold value Th1 is T2. Time T1 is earlier than time T2.

[0046] Therefore, when a large inrush current flows frequently through the first switch 33A (line S1), the magnitude of the resistance value R reaches the resistance threshold value Th1 earlier than when a large inrush current flows infrequently through the first switch 33A (line S2). In other words, the circuit breaker 1 of the present disclosure determines the degree of deterioration of the first switch 33A taking into account the state of the contacts of the first switch 33A, and therefore can operate the first switch 33A in a manner that further enhances its durability.

[0047] Next, the effects of this configuration will be illustrated. The circuit breaker 1 has a first switch 33A that switches a power path 11, which is a path for transmitting power from a power supply unit 10, between a conductive state and a cut-off state. The circuit breaker 1 has a control unit 15 that executes a deterioration determination process that compares a resistance value R of the first switch 33A with a resistance threshold value Th1. If the resistance value R is equal to or greater than the resistance threshold value Th1, the control unit 15 determines that the first switch 33A is in a deteriorated state and notifies the outside that the first switch 33A is in a deteriorated state.

[0048] In the circuit breaker 1, the resistance value R of the first switch 33A can be an index for estimating the state of the first switch 33A. Therefore, it is possible to determine whether the first switch 33A is in a deteriorated state in accordance with the state of the first switch 33A itself, making it easy to maximize the durability of the first switch 33A. Furthermore, since the circuit breaker 1 is configured to notify the outside of the deteriorated state, it is easy to take external measures in accordance with the state of the first switch 33A. Here, a deteriorated state refers to a state in which the first switch 33A has deteriorated compared to when it was first installed in the circuit breaker 1, and its ability to switch the power path 11 between a conductive state and a cut-off state has deteriorated.

[0049] In the circuit breaker 1, the resistance value R is based on the potential difference across the first switch 33A when the first switch 33A is in the on state and a current flows through the power path 11, and on the current flowing through the power path 11. With this configuration, a degraded state is determined if the resistance value R, which is based on the potential difference across the first switch 33A and the current flowing through the power path 11 when the first switch 33A is in the on state and a current flows through the power path 11, is equal to or greater than the resistance threshold value Th1. Therefore, it is possible to determine whether the first switch 33A is in a degraded state in accordance with the state of the first switch 33A itself, and the first switch 33A can be operated in a manner that further enhances its durability.

[0050] The circuit breaker 1 further includes a second switch 33B that switches the power path 11 between a conductive state and a cut-off state. The first switch 33A is switched from an off state to an on state after the second switch 33B is switched, and this causes the power path 11 to start conducting electricity or experience a current increase. The control unit 15 executes a deterioration determination process that compares the resistance value R when the switching control is executed with a resistance threshold value Th1.

[0051] In the switching control, the first switch 33A is switched to the on state later than the second switch 33B, so that an inrush current is likely to flow to the first switch 33A. As a result, the contacts of the first switch 33A are likely to wear (deteriorate). With this configuration, it is possible to determine the deterioration of the first switch 33A in the switching control in which the contacts of the first switch 33A are likely to wear.

[0052] In the circuit breaker 1, the power path 11 includes a high-potential side power path 17 and a low-potential side power path 20 that has a lower potential than the high-potential side power path 17. A second switch 33B is provided in the high-potential side power path 17, and a first switch 33A is provided in the low-potential side power path 20. The circuit breaker 11 further includes a resistor 33D and a third switch 33E connected in series to the resistor 33D, and a parallel switching path 33C in which the resistor 33D and the third switch 33E are connected in parallel to the first switch 33A. The switching control is control in which the first switch 33A is turned off while the second switch 33B and the third switch 33E are turned on to start energizing the power path 11, and then the first switch 33A is switched on while the second switch 33B and the third switch 33E are maintained in the on state.

[0053] When the second switch 33B and the third switch 33E are turned on to start energizing the power path 11 in advance, the resistor 33D prevents the peak of the current flowing through the third switch 33E from becoming too large, while allowing the current to flow through the power path 11. Thereafter, the first switch 33A is switched on while the second switch 33B and the third switch 33E are maintained in the on state, so that the peak of the inrush current flowing through the first switch 33A can be suppressed.

[0054] In the circuit breaker 1, the control unit 15 detects the voltage between both terminals of the first switch 33A. According to this configuration, the resistance value R of the target first switch 33A can be detected more accurately.

[0055] In the circuit breaker 1, the control unit 15 executes a deterioration determination process to compare the resistance value R with the resistance threshold value Th1 when the magnitude of the current flowing through the power path 11 is equal to or greater than the current threshold value Th2. Because the circuit breaker 1 is configured to compare the current flowing through the power path 11 with the current threshold value Th2, for example, it is possible to narrow down the current state used when detecting the resistance value R to a state appropriate for detecting the resistance value R, thereby increasing the reliability of the calculated resistance value R.

[0056] <Other embodiments> The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0057] Unlike the first embodiment, the voltage detection unit may be connected at any position that can be considered to have the same potential as the terminals on both sides of the first switch. For example, as shown in Fig. 4, the voltage detection unit 39 may be connected at a position closer to the power supply side and a position closer to the load side than the position where the parallel switching path 33C is electrically connected to the low-potential side power path 20.

[0058] Unlike the first embodiment, the notification function unit may be configured as a display unit such as a lamp or a display device, and may be configured to notify by display. The notification function unit may be configured as an audio device such as a speaker, and may be configured to notify by audio.

[0059] Unlike the first embodiment, the resistance value calculation unit, the deterioration detection unit, and the notification function unit may be configured as separate information processing devices (separate microcomputers, etc.).

[0060] Unlike the first embodiment, the second switch may be provided on the low-potential side power path and the first switch may be provided on the high-potential side power path. In this case, it is preferable that the parallel switching path is also provided on the high-potential side power path.

[0061] Unlike the first embodiment, the control unit and the control device may be configured as one microcomputer.

[0062] Unlike the first embodiment, the degradation determination process may be performed after determining that the rate of increase in the current in the power path is equal to or less than a certain value. For example, the change in current Ki in the power path per unit time is calculated using the following formula 1: Ki = |A1-A2| / ΔT... (Formula 1) where A1 is the current value A1 detected this time by the current detection unit, A2 is the current value A2 detected last time by the current detection unit, and ΔT is the period ΔT over which the current detection unit repeatedly detects the current value. The current value A2 may be stored, for example, in the RAM of the control unit. The change Ki is the absolute value of the difference between the current values ​​A1 and A2 divided by the period ΔT. For example, if the change Ki remains smaller than a threshold value stored in the memory of the control unit for a predetermined period of time, it may be determined that the fluctuation in the current flowing in the power path has stabilized, and the resistance value of the first switch may then be calculated.

[0063] Unlike the first embodiment, the third switch may not be provided. In this case, the execution of the switching control causes a current rise in which the value of the current flowing through the power path rises sharply.

[0064] Unlike the first embodiment, table data that defines resistance values ​​corresponding to current values ​​and voltage values ​​may be stored in advance in a storage unit, and the resistance values ​​corresponding to the current values ​​and voltage values ​​may be adopted from the table data.

[0065] Unlike the first embodiment, a configuration may be adopted in which table data that defines the resistance value of the switch corresponding to the number of times the switch is opened and closed is stored in advance in a storage unit, and the resistance value corresponding to the number of times the switch is opened and closed is adopted from the table data.

[0066] It is considered that the maximum value of the inrush current in a switch decreases as the resistance value of the switch increases. Therefore, unlike the first embodiment, a configuration may be adopted in which table data that defines the resistance value of the switch corresponding to the maximum value of the inrush current in the switch is stored in advance in a storage unit, and the resistance value corresponding to the maximum value of the inrush current in the switch is adopted from the table data. [Explanation of symbols]

[0067] 1...Shut-off device 10...Power supply section 11…Power line 15...Control unit 15A...Resistance value calculation section 15B…Deterioration detection unit 15C…Notification function section 15D…Storage section 17...High-voltage power line 20...Low potential side power line 33...System main relay 33A…1st switch (switch) 33B…Second switch 33C...Parallel switching path 33D...Resistor 33E…Third switch 35...Load 38...Current detection unit 39...Voltage detection unit 100...Vehicle power supply system A, A1, A2...Current value C: Prescribed control device F...Fuse Ki…Amount of change R…Resistance value Sd...degraded signal Son...On signal Th1: Resistance threshold Th2: Current threshold Th3: Upper limit current threshold ΔT…period V: Voltage value

Claims

1. A vehicle shutoff device having a switch that switches a power path, which is a path for transmitting power from a power supply unit, between a conductive state and a cutoff state, a control unit that executes a deterioration determination process that compares the resistance value of the switch with a resistance threshold value; The resistance value is based on a potential difference across the switch when the switch is in an on state and a current flows through the power path, and on a current flowing through the power path; The control unit calculates the resistance value and executes the deterioration determination process when the magnitude of the current flowing through the power path remains within a range that is equal to or greater than a current threshold and smaller than an upper current threshold for a predetermined period of time, and when the resistance value is equal to or greater than the resistance threshold, determines that the switch is in a deteriorated state and notifies the outside world of the deteriorated state.

2. (delete)

3. Further, a second switch is provided to switch the power path between the conductive state and the cut-off state, A switching control is executed in which the switch is switched from an off state to the on state after the second switch, thereby causing a start of energization or a current increase in the power path, The vehicle shutoff device according to claim 1 , wherein the control unit executes the deterioration determination process by comparing the resistance value when the switching control is executed with the resistance threshold value.

4. The power path includes a high-potential side power path and a low-potential side power path having a lower potential than the high-potential side power path, the second switch is provided on one of the high-potential side power path and the low-potential side power path, and the switch is provided on the other of the high-potential side power path and the low-potential side power path, The power supply further includes a resistor and a third switch connected in series to the resistor, and has a parallel switching path in which the resistor and the third switch are connected in parallel to the switch; 4. The vehicle circuit breaker according to claim 3, wherein the switching control is a control for switching the circuit breaker to the on state while keeping the second circuit breaker in the on state, after which the second circuit breaker and the third circuit breaker are turned on to start energizing the power path while keeping the second circuit breaker in the on state.

5. The vehicle circuit breaker according to claim 4, wherein the control unit detects a voltage between both terminals of the switch.

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