Cutting device for vehicle

Abstract

Provided is a cutting device for a vehicle, which can be used so as to further exhibit the durability of a shutter. A cutoff device (1) is provided with a first switch (33A) that switches, between an ON state and an OFF state, a power path (11) that is a path through which power from a power supply unit (10) is transmitted. The cutting device (1) is provided with a control unit (15) for executing a deterioration determination process for comparing the resistance value (R) of the first shutter (33A) with a resistance threshold value (Th1). When the resistance value (R) is equal to or greater than the resistance threshold (Th1), the control unit (15) determines that the first shutter (33A) is in a degraded state, and notifies the outside that the first shutter (33A) is in the degraded state.

Description

Technical Field

[0001] The present disclosure relates to a cutting device for a vehicle. Background Art

[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 driving unit.

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-188983

[0005] Patent Document 2: Japanese Patent Application Publication No. 2017-225307

[0006] Patent Document 3: Japanese Patent Application Publication No. 2009-11040 Summary of the invention

[0007] Problems to be solved by the invention

[0008] As the power output of the power source progresses, the current value flowing in the power path from the power source to the load becomes larger. In addition, there is a concern that the burden on the switch or circuit breaker existing in the power path increases, and the contacts of the switch or circuit breaker are easily worn. Therefore, it is necessary to determine whether the wear of the contacts of the switch or circuit breaker is progressing, and to use the switch or circuit breaker based on the determination result. As an example, the following method is known: the upper limit of the number of opening and closing times of the switch or circuit breaker is predetermined, and the number of opening and closing times of the switch or circuit breaker is compared with the upper limit value to determine whether the switch or circuit breaker meets the required performance. However, in this method, although the wear of the contacts in the switch or circuit breaker has not progressed and the required performance is met (that is, the state that can be used), when the number of opening and closing times reaches the upper limit, it is judged that the required performance is not met. Therefore, it is expected that a method of using a switch or circuit breaker on the basis of further exerting durability performance.

[0009] The present disclosure has been made based on the above-mentioned circumstances, and an object of the present disclosure is to provide a vehicle cutoff device that can be operated in a manner that further demonstrates the durability of the switch.

[0010] Means for solving problems

[0011] The vehicle disconnection device disclosed in the present invention has a switch that switches a path for transmitting power based on a power supply unit, namely, a power path, between an on state and a cut-off state. The vehicle disconnection device has a control unit that performs a degradation judgment process of comparing a resistance value of the switch with a resistance threshold value. When the resistance value is greater than the resistance threshold value, the control unit judges that the switch is in a degraded state and notifies the outside that it is in the degraded state.

[0012] Effects of the Invention

[0013] According to the present disclosure, the switch can be used in a manner that further demonstrates its durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a circuit diagram illustrating a vehicle power supply system including the vehicle disconnection device according to the first embodiment.

[0015] Figure 2 This is a flowchart showing an example of control by the control unit in the vehicle cutting device according to the first embodiment.

[0016] Figure 3 : is a graph showing the change over time of the resistance value of the first switch.

[0017] Figure 4 It is a circuit diagram showing the connection position of the voltage detection unit with respect to the low potential side power path in another embodiment. DETAILED DESCRIPTION

[0018] [Description of Embodiments of the Present Disclosure]

[0019] First, embodiments of the present disclosure will be described below.

[0020] The vehicle disconnection device (1) disclosed in the present invention is a vehicle disconnection device having a switch for switching a path for transmitting power based on a power supply unit, i.e., a power path, between an on state and a cut-off state. The disconnection device has a control unit that performs a degradation determination process of comparing a resistance value of the switch with a resistance threshold value. When the resistance value is greater than the resistance threshold value, the control unit determines that the switch is in a degraded state and notifies the outside that the switch is in a degraded state.

[0021] In the above-mentioned vehicle disconnection device [1], the resistance value in the switch can be used as an index for estimating the state of the switch. Therefore, it is possible to determine whether the switch is in a degraded state in a form that conforms to the state of the switch itself, so it is easy to exert the durability of the switch. In addition, since the degraded state is notified to the outside, it is easy to take measures that conform to the state of the switch. Here, the degraded state refers to a state in which the switch is deteriorated compared to the initial state when it was installed in the disconnection device, and the performance of switching the power path between the on state and the off state is reduced.

[0022] [2] In the vehicle disconnect device of [1] above, the resistance value is determined based on the potential difference between both sides of the switch and the current flowing in the power path when the switch is in the on state and the current flows in the power path.

[0023] The vehicle disconnect device of the above-mentioned [2] is configured to determine that the switch is in a degraded state when the potential difference between both sides of the switch and the resistance value of the current flowing in the power path when the switch is in the on state and the current flows in the power path is greater than a threshold value. Therefore, it is possible to determine whether the switch is in a degraded state in a form that matches the state of the switch itself, and it is possible to operate in a form that further utilizes the durability performance of the switch.

[0024] [3] The vehicle disconnection device of [2] may further include a second switch for switching the power path between an on state and a cutoff state. The power path may be energized or the current may rise by switching control of the switch from the off state to the on state after the second switch. The control unit may perform a degradation determination process of comparing the resistance value when the switching control is performed with the resistance threshold.

[0025] In the above-mentioned vehicle disconnection device [3], in the switching control, the switch is switched to the on state after the second switch, so the inrush current easily flows through the switch. Therefore, the contacts of the switch are easily worn (degraded). According to this structure, in the switching control in which the contacts of the switch are easily worn, it is possible to determine the deterioration of the switch.

[0026] [4] Based on the above-mentioned vehicle disconnection device [3], 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 either the high potential side power path or the low potential side power path, and a switch may be provided on the other side. The vehicle disconnection device further includes a resistor and a third switch connected in series with the resistor, and may have a parallel switch path in which the resistor and the third switch are connected in parallel with the switch. The switching control may be the following control: after the switch is turned off and the second switch and the third switch are turned on to start energizing the power path, the second switch is maintained in the on state and the switch is switched to the on state.

[0027] The vehicle disconnection device of the above-mentioned [4] can suppress the peak value of the current flowing in the third switch from becoming too large by the resistor when the second switch and the third switch are turned on to energize the power path in advance, and the current can flow in the power path. Then, the second switch is maintained in the on state and the switch is switched to the on state, so that the peak value of the inrush current flowing through the switch can be suppressed.

[0028] [5] In the vehicle disconnecting device of [4] above, the control unit is capable of detecting a voltage between both terminals of the switch.

[0029] The vehicle disconnecting device of the above-mentioned [5] can detect the resistance value of the target switch more accurately.

[0030] [6] In the vehicle disconnection device according to any one of [2] to [5] above, the control unit is capable of executing a degradation determination process that compares a resistance value when the magnitude of the current flowing in the power path is equal to or greater than a current threshold with a resistance threshold.

[0031] The vehicle disconnecting device described in [6] above is a structure that compares the current flowing in the power path with the current threshold value. Therefore, for example, the state of the current used when detecting the resistance value can be limited to a state suitable for detecting the resistance value, thereby improving the reliability of the calculated resistance value.

[0032] <Implementation Method 1>

[0033] 〔Structure of cutting device〕

[0034] Figure 1The vehicle power supply system 100 shown is a power supply system mounted on a vehicle, and includes a power supply unit 10 and a disconnection device 1. The disconnection device 1 includes 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 for transmitting power between the power supply unit 10 and the load 35.

[0035] The power supply unit 10 is a storage battery capable of supplying electric power to the load 35. For example, a battery pack formed by connecting a plurality of single cells such as lead storage batteries, lithium ion batteries, or nickel-metal hydride batteries in series is used as the power supply unit 10.

[0036] 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 is lower in potential than the high potential side power path 17. The output voltage of the power supply unit 10 is equivalent 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 based on the power supply unit 10 to the load 35. A fuse F is provided in the high potential side power path 17. The fuse F cuts off the energization of the high potential side power path 17 when an excessive current flows in the high potential side power path 17.

[0037] In the present disclosure, "electrical connection" is preferably a structure in which the potentials of both connection objects are equal and the connection is in a state of mutual conduction (a state in which current flows). However, it is not limited to this structure. For example, "electrical connection" may also be a structure in which an electrical component is interposed between two connection objects and the two connection objects are connected in a state in which they can be conducted.

[0038] 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 products such as electric components, ECUs, and ADAS target components are applied. The current output from the high potential side terminal of the power supply unit 10 flows through the high potential side power path 17, the load 35, the low potential side power path 20, and the low potential side terminal of the power supply unit 10 in sequence.

[0039] The system main relay 33 is provided between the high potential side power path 17 and the low potential side power path 20 between the power supply unit 10 and the load 35. The system main relay 33 includes a first switch 33A, a second switch 33B, and a parallel switch path 33C as switches. The first switch 33A and the second switch 33B are, for example, relay switches having contacts physically switched between a contact state and a separated state inside. The parallel switch path 33C includes a resistor 33D and a third switch 33E connected in series with the resistor 33D. The third switch 33E is a relay switch having the same structure as the first switch 33A and the second switch 33B. The third switch 33E is a so-called pre-charge relay.

[0040] The first switch 33A is provided in the low potential side power path 20. The second switch 33B is provided in the high potential side power path 17 on the side opposite to the power supply unit 10 via the fuse F. The resistor 33D and the third switch 33E of the parallel switch path 33C are electrically connected to the low potential side power path 20 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, also referred to as the control device C) to switch between the on state and the off state. The first switch 33A, the second switch 33B, and the third switch 33E switch the power path 11 between the on state and the off state by switching between the on state and the off state.

[0041] The current detection unit 38 is interposed in the low potential side power path 20 on the power supply unit 10 side relative to the first switch 33A. The current detection unit 38 includes, for example, a resistor and a differential amplifier, and is configured to output a value indicating a current flowing in the low potential side power path 20 (specifically, an analog voltage corresponding to the value of the current flowing in the low potential side power path 20) as a current value A. That is, the current detection unit 38 detects the current state of the current flowing through the power path 11 as the current value A.

[0042] The voltage detection unit 39 is configured as, for example, a voltage detection circuit, and is configured to output a voltage value V corresponding to a potential difference between a terminal on the power supply unit 10 side and a terminal on the load 35 side in the first switch 33A. That is, the voltage detection unit 39 detects a voltage state of a voltage in the power path 11 as the voltage value V. In other words, the voltage detection unit 39 detects a potential difference between terminals on both sides of the power supply unit 10 side and the load 35 side of the first switch 33A (terminals on both sides of the side where power is supplied to the first switch 33A and the side where power is output) as the voltage value V.

[0043] The control unit 15 is configured as a microcomputer, for example, and includes a storage unit 15D including a CPU, a ROM, a RAM, and a nonvolatile memory. The control unit 15 includes a resistance value calculation unit 15A, a degradation 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 the current detection unit 38 and the voltage detection unit 39, respectively, and calculate and detect a resistance value R based on these values. For example, the resistance value R is obtained by dividing the voltage value V by the current value A. The control unit 15 detects the voltage between the two terminals of the first switch 33A based on the voltage value V from the voltage detection unit 39.

[0044] The degradation detection unit 15B is configured to be able to perform a degradation determination process of comparing the resistance value R calculated in the resistance value calculation unit 15A with the resistance threshold value Th1 stored in the storage unit 15D of the control unit 15. The degradation detection unit 15B is configured to be able to output a degradation signal Sd when it is determined in the degradation determination process that the magnitude of the resistance value R is greater than the resistance threshold value Th1. The degradation signal Sd is output when the first switch 33A is in a degraded state. That is, the control unit 15 determines that the first switch 33A is in a degraded state when the resistance value R is greater than the resistance threshold value Th1. The degradation detection unit 15B does not output the degradation signal Sd when it is determined in the degradation determination process that the magnitude of the resistance value R is less than the resistance threshold value Th1. In this case, the control unit 15 determines that the first switch 33A is not in a degraded state.

[0045] The notification function unit 15C is constituted by, for example, a communication device, and is configured to make a report by transmitting information to an external device (not shown) such as a BMS (Battery Management System) based on the degradation signal Sd input from the degradation detection unit 15B.

[0046] [Regarding control in the control unit]

[0047] Next, refer to Figure 2 An example of control performed by the control unit 15 is described below. For example, in a vehicle equipped with the vehicle power supply system 100, when the ignition switch is turned off, the first switch 33A, the second switch 33B of the system main relay 33, and the third switch 33E of the parallel switch path 33C are maintained in the open state. At this time, the power path 11 is in the cut-off state in which the power supply from the power supply unit 10 to the load 35 is cut off.

[0048] From this state, first, step S1 is executed to switch the ignition switch from off to on. Then, when the process moves to step S2, an on signal Son is output from the control device C (see Figure 1), a switching control is performed in which the first switch 33A, the second switch 33B, and the third switch 33E are switched from the disconnected state to the connected state based on the connection signal Son. Specifically, in the switching control, based on the connection signal Son output from the control device C, the second switch 33B, the third switch 33E, and the first switch 33A are switched from the disconnected state to the connected state in the order. In other words, the switching control is a control in which, after the first switch 33A is set to the disconnected state and the second switch 33B and the third switch 33E are set to the connected state so that the power path 11 starts to be energized, the second switch 33B and the third switch 33E are maintained in the connected state and the first switch 33A is switched to the connected state. That is, the first switch 33A is switched from the disconnected state to the connected state after the second switch 33B. In addition, the timing of outputting the connection signal Son from the control device C to each switch can be variously changed. That is, the control device C can perform control different from the switching control.

[0049] For example, by staggering the timing at which the control device C outputs the on signal Son to 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 are switched to the on state can be staggered. In addition, when the second switch 33B and the third switch 33E are set to the on state, the power path 11 starts to be energized. Since the resistor 33D is connected in series with the third switch 33E, the current starts to flow slowly in the power path 11 in a gradually increasing manner.

[0050] In addition, when the first switch 33A is turned on, the power path 11 is turned on to allow 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, the inrush current immediately flows through the first switch 33A. At this time, a current rise occurs in which the current value A flowing in the power path 11 rises sharply. In this way, the start of energization of the power path 11 or the current rise occurs by performing the switching control. After the first switch 33A is switched to the on state, the inrush current continues to flow for a predetermined short time, and after the predetermined short time has passed, the current flowing through the first switch 33A stabilizes to stay in a predetermined range smaller than the magnitude of the inrush current. In this way, the first switch 33A is turned on, and the current flows in the power path 11.

[0051] Furthermore, when the process shifts to step S3, the control unit 15 determines whether a predetermined short time has passed since the power path 11 was switched to the on state (when the first switch 33A was switched to the on state). For example, the control unit 15 has a timer function and is configured to be able to measure a predetermined short time since the power path 11 was switched to the on state. Whether the power path 11 is switched to the on state can be determined based on, for example, the degree to which the value of the current value A changes within a predetermined time (the amount of change in the current value A per unit time). In step S3, if the control unit 15 determines that the predetermined short time has not passed since the power path 11 was switched to the on state (No in step S3), the process of step S3 is repeated.

[0052] Furthermore, in step S3, when the control unit 15 determines that a predetermined short time has passed since the power path 11 was switched to the conducting state (Yes in step S3), the process is transferred to step S4. When transferring to step S4, the control unit 15 determines whether the magnitude of the current value A is maintained 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 the current threshold Th2 and the upper limit current threshold Th3 greater than the current threshold Th2 stored in the storage unit 15D of the control unit 15. For example, the control unit 15 is configured to be able to use the timer function of the control unit 15 to determine whether the state in which the magnitude of the current value A is greater than the current threshold Th2 and less than the upper limit current threshold Th3 continues for a predetermined time (that is, the change of the current flowing in the power path 11 is stable). In step S4, if the control unit 15 determines that the state in which the magnitude of the current value A is greater than the current threshold Th2 and less than the upper limit current threshold Th3 does not continue for a predetermined time (No in step S4), the process of step S4 is repeated.

[0053] In step S4, if the control unit 15 determines that the current value A is greater than or equal to the current threshold value Th2 and less than the upper current threshold value Th3 for a predetermined time (Yes in step S4), the process proceeds to step S5. When the process proceeds to step S5, the control unit 15 obtains the resistance value R in the resistance value calculation unit 15A based on the current value A and the voltage value V input from the current detection unit 38 and the voltage detection unit 39, respectively. That is, the control unit 15 detects the resistance value R when the current value A flowing through the power path 11 is greater than or equal to the current threshold value Th2. Then, the process proceeds to step S6.

[0054] When the process moves to step S6, the control unit 15 performs a degradation determination process in which the resistance value R is compared with the resistance threshold value Th1 in the degradation detection unit 15B. The control unit 15 performs a degradation determination process in which the resistance value R is compared with the resistance threshold value Th1 when the switching control is performed by the control device C. For example, in the degradation determination process, if it is determined that the resistance value R is greater than the resistance threshold value Th1 (yes in step S6), the process moves to step S7, and the degradation signal Sd is output from the degradation detection unit 15B.

[0055] In contrast, in the degradation determination process, if it is determined that the magnitude of the resistance value R is less than the resistance threshold value Th1 (No in step S6), the degradation signal Sd is not output. In this way, the control unit 15 performs a degradation determination process of comparing the resistance value R when the magnitude of the current flowing in 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 performs a degradation determination process of comparing the resistance value R of the first switch 33A based on the voltage value V (potential difference) on both sides of the first switch 33A and the current value A flowing in the power path 11 when the first switch 33A is in the on state and the current flows in the power path 11 with the resistance threshold value Th1 to determine the degree of degradation of the first switch 33A.

[0056] Next, when the degradation signal Sd is input to the notification function unit 15C, the notification function unit 15C sends information to an external device (not shown). In other words, the notification function unit 15C of the control unit 15 notifies the outside that the device is in a degradation state. Figure 2 The shown processing ends.

[0057] As the switching control of the control device C is repeated, the number of times the first switch 33A is switched to the on state increases. As a result, wear and oxidation of the contacts in the first switch 33A progress, 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 that gradually increases as the number of times the switch to the on state increases with the resistance threshold Th1.

[0058] For example, when a large inrush current frequently flows through the first switch 33A, the resistance value R of the first switch 33A increases as time passes. Figure 3In contrast, when the frequency of a large inrush current flowing through the first switch 33A is low, the degree of increase in the resistance value R of the first switch 33A over time becomes smaller as shown in the straight line S2. When the frequency of a large inrush current flowing through the first switch 33A is high (straight line S1), the time when the resistance value R reaches the resistance threshold value Th1 is T1, and when the frequency of a large inrush current flowing through the first switch 33A is low (straight line S2), the time when the resistance value R reaches the resistance threshold value Th1 is T2. In addition, the time T1 is a timing earlier than the time T2.

[0059] Therefore, when the frequency of a large inrush current flowing through the first switch 33A is high (straight line S1), the resistance value R reaches the resistance threshold value Th1 earlier than when the frequency of a large inrush current flowing through the first switch 33A is low (straight line S2). That is, the disconnecting device 1 of the present disclosure determines the degree of deterioration of the first switch 33A in consideration of the state of the contact of the first switch 33A, and thus can be operated in a form that further exerts the durability of the first switch 33A.

[0060] Next, the effects of this structure are exemplified.

[0061] The disconnection device 1 includes a first switch 33A that switches the power path 11, which is a path for transmitting power from the power supply unit 10, between an on state and a cutoff state. The disconnection device 1 includes a control unit 15 that performs a degradation determination process of comparing the resistance value R of the first switch 33A with the resistance threshold Th1. When the resistance value R is greater than or equal to the resistance threshold Th1, the control unit 15 determines that the first switch 33A is in a degraded state, and notifies the outside that it is in a degraded state.

[0062] In the disconnection device 1, the resistance value R of the first switch 33A can be used as 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 degraded state in a form that matches the state of the first switch 33A itself, so it is easy to exert the durability of the first switch 33A. In addition, since the degraded state is notified to the outside, it is easy to take measures that match the state of the first switch 33A. Here, the degraded state refers to a state in which the first switch 33A is deteriorated compared to the initial state when it was provided in the disconnection device 1, and the performance of switching the power path 11 between the on state and the off state is reduced.

[0063] In the disconnecting device 1, the resistance value R is based on the potential difference between both sides of the first switch 33A and the current flowing through the power path 11 when the first switch 33A is in the on state and the current flows through the power path 11. According to this configuration, when the resistance value R based on the potential difference between both sides of the first switch 33A and the current flowing through the power path 11 when the first switch 33A is in the on state and the current flows through the power path 11 is greater than the resistance threshold Th1, it is determined that the state is degraded. Therefore, it is possible to determine whether the first switch 33A is in a degraded state in a form that matches the state of the first switch 33A itself, and it is possible to operate in a form that further exerts the durability performance of the first switch 33A.

[0064] The disconnection device 1 further includes a second switch 33B that switches the power path 11 between the on state and the off state. The first switch 33A is switched from the off state to the on state after the second switch 33B, so that the power path 11 starts to be energized or the current rises. The control unit 15 performs a degradation determination process of comparing the resistance value R when the switching control is performed with the resistance threshold Th1.

[0065] In the switching control, the first switch 33A is switched to the on state later than the second switch 33B, so the inrush current easily flows through the first switch 33A. Therefore, the contact of the first switch 33A is easily worn (degraded). According to this structure, in the switching control in which the contact of the first switch 33A is easily worn, it is possible to determine the degradation of the first switch 33A.

[0066] In the cutoff device 1, the power path 11 includes a high potential side power path 17 and a low potential side power path 20 having 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. In addition, a resistor 33D and a third switch 33E connected in series with the resistor 33D are provided, and a parallel switch path 33C in which the resistor 33D and the third switch 33E are connected in parallel with the first switch 33A is provided. The switching control is a control in which, after the first switch 33A is set to the off state and the second switch 33B and the third switch 33E are set to the on state to start energizing the power path 11, the second switch 33B and the third switch 33E are maintained in the on state and the first switch 33A is switched to the on state.

[0067] When the second switch 33B and the third switch 33E are turned on and the power path 11 starts to be energized in advance, the resistor 33D can suppress the peak value of the current flowing in the third switch 33E from becoming too large, and the current can flow in the power path 11. Then, the second switch 33B and the third switch 33E are maintained in the on state and the first switch 33A is switched to the on state, so that the peak value of the rush current flowing in the first switch 33A can be suppressed.

[0068] In the interrupter 1, the control unit 15 detects the voltage between the two 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.

[0069] In the cutoff device 1, the control unit 15 performs a degradation determination process of comparing the resistance value R when the magnitude of the current flowing in the power path 11 is equal to or greater than the current threshold value Th2 with the resistance threshold value Th1. The cutoff device 1 is a structure that compares the current flowing in the power path 11 with the current threshold value Th2, so that, for example, the state of the current used when detecting the resistance value R can be limited to a state suitable for detecting the resistance value R, and the reliability of the calculated resistance value R can be improved.

[0070] <Other Implementation Methods>

[0071] The embodiments disclosed herein are illustrative in all aspects and should not be construed as restrictive. The scope of the present invention is not limited to the embodiments disclosed herein but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0072] Unlike the first embodiment, the voltage detection unit can be connected to a position that is considered to have the same potential as the terminals on both sides of the first switch. Figure 4 As shown, the voltage detection unit 39 may be connected to a position closer to the power supply unit 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 .

[0073] Different from the first embodiment, the notification function unit may be configured as a display unit such as a lamp or a display device to make notification by display. The notification function unit may be configured as an audio device such as a speaker to make notification by audio.

[0074] Unlike the first embodiment, the resistance value calculation unit, the degradation detection unit, and the notification function unit may be configured as separate information processing devices (separate microcomputers, etc.).

[0075] Unlike Embodiment 1, the second switch may be provided in the low potential side power path and the first switch may be provided in the high potential side power path. In this case, it is preferable that the parallel switch path is also provided in the high potential side power path.

[0076] Different from the first embodiment, the control unit and the control device may be configured as one microcomputer.

[0077] Unlike the first embodiment, the degradation determination process may be performed after it is determined that the rising speed of the current in the power path is below a certain value. For example, the change amount Ki of the current in the power path per unit time is calculated by the following formula 1. Ki = |A1-A2| / ΔT... (Formula 1), where A1 is the current value A1 detected by the current detection unit this time, A2 is the current value A2 detected by the current detection unit last time, and ΔT is the period ΔT of the time when the current detection unit repeatedly detects the current value. The current value A2 is, for example, a structure that can be stored in the RAM of the control unit. The change amount Ki is the value obtained by dividing the absolute value of the difference between the current value A1 and the current value A2 by the period ΔT. For example, when the state in which the change amount Ki is smaller than the threshold value stored in the storage unit of the control unit continues for a predetermined time, it may be determined that the change of the current flowing in the power path is stable, and then the resistance value of the first switch is calculated.

[0078] Unlike Embodiment 1, the third switch may not be provided. In this case, a current rise in which the value of the current flowing in the power path rises sharply occurs by executing the switching control.

[0079] Unlike the first embodiment, table data defining 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.

[0080] Unlike the first embodiment, table data defining the resistance value of the switch corresponding to the number of times the switch is opened and closed may be stored in advance in the storage unit, and the resistance value corresponding to the number of times the switch is opened and closed may be adopted from the table data.

[0081] It is conceivable that the maximum value of the inrush current in the switch decreases as the resistance value of the switch increases. Therefore, unlike the first embodiment, table data for determining the resistance value of the switch corresponding to the maximum value of the inrush current in the switch may be stored in advance in the storage unit, and the resistance value corresponding to the maximum value of the inrush current in the switch may be adopted from the table data.

[0082] Description of Reference Numerals

[0083] 1… Cutting device

[0084] 10…Power supply

[0085] 11…Power Path

[0086] 15…Control Department

[0087] 15A…Resistance value calculation unit

[0088] 15B…Deterioration detection unit

[0089] 15C…Notification Function Department

[0090] 15D… Storage

[0091] 17…High potential side power path

[0092] 20…Low potential side power path

[0093] 33…System main relay

[0094] 33A…First switch (switch)

[0095] 33B…Second switch

[0096] 33C…Parallel opening and closing paths

[0097] 33D…Resistors

[0098] 33E…Third switch

[0099] 35…Load

[0100] 38…Current detection unit

[0101] 39…Voltage detection unit

[0102] 100…Vehicle power supply system

[0103] A, A1, A2...current value

[0104] C…predetermined control device

[0105] F…Fuse

[0106] Ki…Change

[0107] R…Resistance value

[0108] Sd…degraded signal

[0109] Son...get the signal

[0110] Th1…Resistance threshold

[0111] Th2…Current threshold

[0112] Th3…upper current threshold

[0113] ΔT…period

[0114] V…voltage value.

Claims

1. A vehicle disconnection device having a switch for switching a power path, that is, a path for transmitting power from a power supply unit, between an on state and a cut-off state, The vehicle disconnecting device includes a control unit that performs a degradation determination process of comparing a resistance value of the switch with a resistance threshold value. When the resistance value is equal to or greater than the resistance threshold, the control unit determines that the switch is in a degraded state, and notifies the outside that the switch is in the degraded state.

2. The vehicle cutting device according to claim 1, wherein: The resistance value is determined based on a potential difference between both sides of the switch and a current flowing through the power path when the switch is in the on state and a current flows through the power path.

3. The vehicle cutting device according to claim 2, wherein: The vehicle disconnection device further includes a second switch configured to switch the electric power path between the on state and the off state. The switch is configured to start energizing the power path or increase the current by executing switching control in which the switch is switched from the off state to the on state after the second switch. The control unit executes the degradation determination process of comparing the resistance value when the switching control is executed with the resistance threshold value.

4. The cutting device for a vehicle according to claim 3, wherein: 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 in one of the high potential side power path and the low potential side power path, and the switch is provided in the other. The vehicle disconnecting device further includes a resistor and a third switch connected in series with the resistor, and the vehicle disconnecting device has a parallel switching path that connects the resistor and the third switch in parallel with the switch. The switching control is control for switching the switch to the on state while maintaining the second switch in the on state after the switch is turned off and the second and third switches are turned on to start energizing the power path.

5. The vehicle cutting device according to claim 4, wherein: The control unit detects a voltage between two terminals of the switch.

6. The vehicle cutting device according to any one of claims 2 to 5, wherein: The control unit executes the degradation determination process of comparing the resistance value when the magnitude of the current flowing in the power path is equal to or greater than a current threshold with the resistance threshold.

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