Protective device

Abstract

To provide a protection device that keeps costs down.SOLUTION: A protection device 70 is used in a power supply system 100 that supplies power to loads 92, 93, and 94 and includes a power path 3 and a relay 10. The power path 3 includes a first conductive path 1 electrically connected to a first power supply portion 90 and a second conductive path 2 electrically connected to a second power supply section 95. The relay 10 switches between a permissive state in which energization between the first conductive path 1 and the second conductive path 2 is permitted, and a cutoff state in which energization is cut off. The first conductive path 1 is provided with first connection portions C2 and C3 in a protection area P1, which is a predetermined range from the relay 10 to the first power supply portion 90 side. The first connection portions C2, C3, and C4 of the first conductive path 1 are all covered with a protector 40, and the first conductive path 1 and the outside of the protector 40 are insulated by the protector 40 in the protection area P1. The second conductive path 2 is electrically connected to a load 92, which is the load to be protected among the loads 92, 93, and 94.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a protection device. [Background technology]

[0002] Patent Document 1 discloses an arrangement structure of a wire harness that connects a battery and an inverter device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-55686 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a connection portion connecting a wire harness to a connection object, a configuration in which connectors are fitted together is generally adopted to simplify installation work. When such a configuration is applied to a vehicle, it is considered that the connector is likely to be worn due to vibration or deformed due to exposure to high temperatures. In anticipation of such a case, a configuration is known in which a wire harness is provided with a relay that immediately separates a part where a ground fault has occurred from a load so that a ground fault may occur in the wire harness. In such a configuration, there is a tendency that the interruption operation of the relay is required to be performed in a shorter time in order to immediately separate the part where a ground fault has occurred, and there is a concern that the relay will become expensive.

[0005] The present disclosure has been completed in light of the above circumstances, and has an object to provide a protection device that keeps costs from increasing. [Means for solving the problem]

[0006] The protection device of the present disclosure comprises: A protection device for use in a power supply system that supplies power to a load, comprising: a power path including a first conductive path electrically connected to a first power supply unit and a second conductive path electrically connected to a second power supply unit; a cutoff unit that switches between a permissive state that permits current flow between the first conductive path and the second conductive path and a cutoff state that cuts off the current flow; Equipped with the first conductive path is provided with a first connection portion in a protection region that is a predetermined range from the interrupter to the first power supply portion, the first connection portion is entirely covered with a protector, and the first conductive path is insulated from an outside of the protector by the protector in the protection region, The second conductive path is electrically connected to a load to be protected among the loads. Effect of the Invention

[0007] According to the present disclosure, it is possible to prevent costs from increasing. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a power supply system provided with a protection device according to a first embodiment. [Diagram 2] FIG. 2 is a graph showing a change in voltage at a second connection part of a path supplying power to a load to be protected when a ground fault occurs in a branch path on the first conduction path side of a power supply system provided with a protection device of embodiment 1. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of a power supply system provided with a protection device of embodiment 1, and shows a state in which a ground fault has occurred in a branch path electrically connected to a first connection part at a position closest to the load to be protected among the ends other than the first connection part connected to the relay. [Figure 4] FIG. 4 is a schematic diagram showing the configuration of a power supply system provided with a protection device of embodiment 1, and shows a state in which a ground fault has occurred in a branch path electrically connected to a first connection part at a position farthest from the load to be protected among the ends other than the first connection part connected to the relay. [Diagram 5]FIG. 5 is a schematic diagram showing the configuration of a power supply system provided with a protection device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The following describes exemplary embodiments of the present disclosure. The following features [1] to [5] may be combined in any manner that is not inconsistent.

[0010] [1] The protective device disclosed herein is used in a power supply system that supplies power to a load. The protective device includes a power path having a first conductive path electrically connected to a first power supply unit and a second conductive path electrically connected to a second power supply unit, and a cutoff unit that switches between an allowable state that allows current flow between the first conductive path and the second conductive path and a cutoff state that cuts off current flow. The first conductive path has a first connection unit in a protection area that is a predetermined range from the cutoff unit to the first power supply unit side. The first conductive path has the entire first connection unit covered by a protector, and in the protection area, the first conductive path is insulated from the outside of the protector by the protector. The second conductive path is electrically connected to a load to be protected among the loads.

[0011] The first conductive path of the protection device of [1] above has a first connection part provided in a protection area, which is a predetermined range from the interrupter to the first power supply part, and the entire first connection part is covered by a protector. In the protection area, the first conductive path is insulated from the outside of the protector by the protector, so that it is possible to prevent a ground fault from occurring at the first connection part and to easily keep the position where a ground fault occurs away from the protected load. Therefore, when a ground fault occurs in the first conductive path, the voltage applied to the protected load connected to the second conductive path can be made difficult to drop due to the resistance component inherent to the power path, and the operation of the protected load can be made difficult to stop.

[0012] [2] The first conductive path of the protective device of [1] above may have a protective area continuously covered by the protector.

[0013] The first conductive path of the protective device of the above [2] has a protected area continuously covered by the protector. This prevents a ground fault from occurring in the protected area and makes it easy to keep the location where the ground fault occurs away from the load to be protected. Therefore, when a ground fault occurs in the first conductive path, the voltage applied to the load to be protected connected to the second conductive path is unlikely to drop due to the inherent resistance component of the power path, making it difficult to stop the operation of the load to be protected.

[0014] [3] In the protection device of [1] or [2] above, the resistance value of the power path from the position where the protected load is electrically connected in the second conductive path to the end closest to the protected load among the ends in the protection area other than the first connection part connected to the interrupter is a first resistance value Ry. The resistance value of the power path from the second power supply part to the position where the protected load is electrically connected in the second conductive path is a second resistance value Rx. When the output voltage of the second power supply part is E and the guaranteed operating voltage of the protected load is Vs, the first resistance value Ry and the second resistance value Rx can satisfy formula 1. Rx / Ry≦(E-Vs) / Vs...Formula 1

[0015] In the protection device described in [3] above, even if a ground fault occurs at an end closest to the protected load among the ends other than the first connection part connected to the interrupter in the protection area from the protected load, the voltage applied to the protected load is equal to or higher than the guaranteed operating voltage of the protected load. This makes it difficult to stop the operation of the protected load. The guaranteed operating voltage here is the minimum voltage required for the protected load to operate normally.

[0016] [4] The second conductive path of the protective device according to any one of [1] to [3] above has a second connection part provided between the second power supply part and the interrupter part, the second connection part being covered by a protector, and includes a branch path electrically connecting the load and the second connection part. The branch path may have a third connection part electrically connected to the load covered by a protector.

[0017] The protection device described in [4] above can effectively prevent ground faults from occurring on the second conductive path side by preferentially protecting the second connection part in the second conductive path and also preferentially protecting the third connection part of the branch path connected to the load.

[0018] [5] The interrupter of any of the protective devices described above in [1] to [4] may be a mechanical relay.

[0019] The protection device described in [5] above is easy to continue operation of the load to be protected without stopping even if a ground fault occurs. Therefore, it is possible to use a mechanical relay, which operates slower than a semiconductor relay, in the interrupter, and by using a mechanical relay, it is easy to suppress high costs.

[0020] [Details of the embodiment of the present disclosure]

[0021] <Embodiment 1> [Power supply system configuration] 1 illustrates a power supply system 100 provided with a protection device 70 according to the first embodiment. The power supply system 100 is used as a power supply that supplies power to loads 92, 93, 94, etc. of a vehicle in which the power supply system 100 is installed to operate them. The power supply system 100 has a first power supply unit 90, a second power supply unit 95, and a protection device 70.

[0022] The first power supply unit 90 and the second power supply unit 95 are configured as DC power supplies such as lithium ion batteries, lead storage batteries, etc. The output voltage of the first power supply unit 90 and the second power supply unit 95 is, for example, 12V.

[0023] [Configuration of protective device] The protective device 70 is used in the power supply system 100. The protective device 70 includes branch paths B1, B2, B3, B4, and B5, a power path 3, a relay 10 which is an interrupter, and a protector 40.

[0024] The branch paths B1, B2, B3, B4, and B5 are, for example, configured such that third connection parts Cb1, Cb2, Cb3, Cb4, and Cb5 made of metal terminal fittings covered with a synthetic resin housing are provided at both ends of the harness.

[0025] The power path 3 is a path for transmitting power between the first power supply unit 90 and the second power supply unit 95. The power path 3 has a first conductive path 1 and a second conductive path 2. The first conductive path 1 is provided with a plurality of first connection parts C1, C2, C3, and C4. The first connection part C1 is configured to be electrically connectable to the first power supply unit 90. The high-potential terminal of the first power supply unit 90 is electrically connected to the first connection part C1 of the first conductive path 1. The first connection part C4 is configured as a connector in a form in which a metal terminal fitting is covered with a synthetic resin housing, for example. One end of the relay 10 is electrically connected to the first connection part C4. The first connection parts C2 and C3 are configured as connectors in a form in which a metal terminal fitting is covered with a synthetic resin housing, for example, so that a mating connector can be detached. The term "detachable" as used herein includes the fact that the connectors can be attached and detached using a jig and the fact that the connectors can be attached and detached using a jig without using a jig. The first connection portions C2 and C3 are electrically connected to third connection portions Cb1 and Cb2 provided at one end of the branch paths B1 and B2, respectively.

[0026] 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 is not limited to this configuration. For example, "electrically connected" may mean a configuration in which the two connection objects are connected in a state in which the two connection objects can be conductive with an electric component interposed between them.

[0027] The second conductive path 2 is provided with a plurality of second connection parts C5, C6, C7, C8, and C9. The second connection part C9 is electrically connectable to the second power supply unit 95. The high-potential terminal of the second power supply unit 95 is electrically connected to the second connection part C9 of the second conductive path 2. The second connection part C5 is configured as a connector in which a metal terminal is covered with a synthetic resin housing, for example. The other end of the relay 10 is electrically connected to the second connection part C5. The second connection parts C6, C7, and C8 are configured as connectors in which a metal terminal is covered with a synthetic resin housing, for example, so that a mating connector can be attached and detached. The second connection parts C6, C7, and C8 are electrically connected to third connection parts Cb3, Cb4, and Cb5 provided at one end of the branch paths B3, B4, and B5, respectively.

[0028] Loads 92, 93, and 94 are electrically connected to third connection parts Cb3, Cb4, and Cb5 provided at the other ends of branch paths B3, B4, and B5, respectively. Each of these loads 92, 93, and 94 is configured as an in-vehicle load that operates by receiving power supply from the first power supply unit 90 or the second power supply unit 95. These loads 92, 93, and 94 correspond to by-wire loads such as a shift system, a steering system, and a brake system. The magnitudes of the operation-guaranteed voltages Vs (hereinafter also simply referred to as operation-guaranteed voltages) of the respective loads 92, 93, and 94 are Vs1 (V), Vs2 (V), and Vs3 (V).

[0029] The relay 10 is disposed between a first power supply unit 90 and a second power supply unit 95. The relay 10 switches between a permissive state in which current is permitted to flow between the first conductive path 1 and the second conductive path 2, and a cut-off state in which current is cut off between the first conductive path 1 and the second conductive path 2. The relay 10 is, for example, a mechanical relay. The relay 10 is configured to be controllable by a control unit 30.

[0030] The protector 40 has a first protector 40A and a second protector 40B. The first protector 40A and the second protector 40B are made of synthetic resin. The first protector 40A has a storage space formed therein for storing a part of the first conductive path 1 and a part of the branch path B1. The first protector 40A continuously covers a protection area P1, which is a region including the first connection part C4 connected to the relay 10 and the first connection parts C2 and C3 connected to the branch paths B1 and B2, and is a predetermined range from the first connection part C4 to the first power supply unit 90 side. In the protection area P1, all of the first connection parts C2 and C3 in the first conductive path 1 are covered by the first protector 40A. That is, the protection area P1 of the first conductive path 1 is continuously covered by the protector 40. In the protection region P1, the first conductive path 1 is insulated from the outside of the first protector 40A by the first protector 40A.

[0031] The second protector 40B has a storage space formed therein for storing the second conductive path 2 and the branch paths B3, B4, and B5. The second protector 40B is an area including the second connection part C5 connected to the relay 10 and the second connection parts C6, C7, and C8 connected to the branch paths B3, B4, and B5, and continuously covers the area from the second connection part C5 to the second connection part C9 connected to the second power supply unit 95 as a protection area P2. In the protection area P2, the second conductive path 2 and the branch paths B3, B4, and B5 are insulated from the outside of the second protector 40B by the second protector 40B. Thus, the second conductive path 2 is covered by the second protector 40B at the second connection part C9 connected to the second power supply unit 95 and the second connection parts C6, C7, and C8 connected to the third connection parts Cb3, Cb4, and Cb5 of the branch paths B3, B4, and B5. In the branch paths B3, B4, B5, the third connection parts Cb3, Cb4, Cb5 connected to the loads 92, 93, 94 are covered by the second protector 40B. In this way, the second conductive path 2 is provided from the second power supply unit 95 to the relay 10, and the second connection parts C6, C7, C8 to which the third connection parts Cb3, Cb4, Cb5 are detachable are covered by the protector 40.

[0032] A first voltage detection unit 50 is interposed in the first conductive path 1. The first voltage detection unit 50 detects a first voltage V1 at a predetermined position in the first conductive path 1 (a position closer to the first power supply unit 90 than the relay 10) and provides a detection value corresponding to the first voltage V1 to the control unit 30. The control unit 30 can identify the voltage value at the predetermined position of the first conductive path 1 based on the detection value input from the first voltage detection unit 50.

[0033] A second voltage detection unit 51 is provided on the second conductive path 2. The second voltage detection unit 51 detects a second voltage V2 at a predetermined position on the second conductive path 2 (a position closer to the second power supply unit 95 than the relay 10) and provides a detection value corresponding to the second voltage V2 to the control unit 30. The control unit 30 can identify the voltage value at the predetermined position on the second conductive path 2 based on the detection value input from the second voltage detection unit 51.

[0034] The control unit 30 is mainly constituted by, for example, a microcomputer, and has an arithmetic device such as a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), an A / D converter, etc. The control unit 30 controls the relay 10 to be on. Then, the relay 10 is turned on and enters an allowable state in which conduction between the first conductive path 1 and the second conductive path 2 is permitted. The control unit 30 controls the relay 10 to be off. Then, the relay 10 is turned off and enters an interrupted state. When in the interrupted state, the relay 10 does not pass current in either direction (i.e., the direction toward the first conductive path 1 and the direction toward the second conductive path 2), and in this state, the current between the first conductive path 1 and the second conductive path 2 is completely interrupted.

[0035] The control unit 30 is configured to receive the first voltage V1 in the first conductive path 1 and the second voltage V2 in the second conductive path 2 from the first voltage detection unit 50 and the second voltage detection unit 51, respectively. The control unit 30 detects an abnormality such as a ground fault that has occurred in each of the first conductive path 1 and the second conductive path 2 based on the first voltage V1 and the second voltage V2 input from the first voltage detection unit 50 and the second voltage detection unit 51, respectively. For example, the control unit 30 is configured to be able to compare a detection value corresponding to the first voltage V1 from the first voltage detection unit 50 with a threshold value stored in its own memory. For example, when the control unit 30 determines that the magnitude of this detection value is equal to or less than the threshold value, it controls the relay 10 to be turned off. The control unit 30 can also compare a detection value corresponding to the second voltage V2 from the second voltage detection unit 51 with a threshold value stored in its own memory, and when it determines that the magnitude of this detection value is equal to or less than the threshold value, it can also control the relay 10 to be turned off.

[0036] [About the action of protective devices] Next, the operation of the protection device 70 will be described taking as an example a case where the load 92 of the loads 92, 93, and 94 is the load to be protected. The load 92, which is the load to be protected among the loads 92, 93, and 94, is electrically connected to the second conductive path 2. The load to be protected here is a load to which it is desirable to set the magnitude of the voltage applied to be equal to or greater than the guaranteed operating voltage when a ground fault occurs.

[0037] For example, as shown in Fig. 2, the output voltage E (V) from the second power supply unit 95 is applied to the second connection C6 (i.e., the second connection that supplies power to the load to be protected) from time T0. Then, a ground fault occurs in the branch path B2 at time T11 (see Fig. 3). The potential at the position where the ground fault occurs in the branch path B2 becomes the same potential as the ground potential V0 in the vehicle (see Fig. 3). Then, after time T11, the voltage at the second connection C6 suddenly decreases.

[0038] The first conductive path 1 and the second conductive path 2 have resistance components. Here, as shown in FIG. 3, the first connection part C3 of the first conductive path 1 to which the branch path B2 in which a ground fault has occurred is electrically connected is the end part closest to the load 92 among the ends from the load 92 to the first connection part C4 electrically connected to the relay 10 in the protection area P1. The resistance value of the resistance component of the power path 3 from the first connection part C3 to the second connection part C6 (i.e., the second connection part to which the third connection part Cb3 of the branch path B3, which is the position to which the load 92 is electrically connected in the second conductive path 2, is electrically connected) is defined as a first resistance value Ry. The resistance value of the resistance component of the power path 3 from the second connection part C9 to which the second power supply unit 95 is electrically connected to the second connection part C6, which is the position to which the load 92 is electrically connected in the second conductive path 2, is defined as a second resistance value Rx. The ground potential V0 is defined as 0 (V), and the output voltage of the second power supply unit 95 is defined as E (V). In this case, the voltage Vd3 at the second connection point C6 (hereinafter also simply referred to as voltage Vd3) can be expressed as Vd3=E×(Ry / (Rx+Ry)). In other words, the voltage Vd3 is a voltage obtained by dividing the output voltage of the second power supply unit 95 by the second resistance value Rx and the first resistance value Ry.

[0039] The magnitude of the guaranteed operating voltage of the load 92 is Vs1 (V). Therefore, in the above formula, the first resistance value Ry and the second resistance value Rx are values ​​that make the voltage Vd3 equal to or greater than Vs1 (V) (i.e., Vd3≧Vs1). This allows the load 92 to continue to operate normally. That is, E×(Ry / (Rx+Ry))≧Vs1. By modifying this formula, we obtain Rx / Ry≦(E-Vs1) / Vs1. In other words, when the first resistance value Ry and the second resistance value Rx satisfy this formula, as shown in FIG. 2, the voltage Vd3 can be maintained at or greater than Vs1 (V) although it decreases rapidly after time T11. This allows the load 92 to continue to operate normally even if a ground fault occurs.

[0040] The control unit 30 compares the detection value corresponding to the first voltage V1 input from the first voltage detection unit 50 with the threshold value stored in its own memory, and determines that the detection value has become equal to or less than the threshold value. Then, at time T12, the control unit 30 controls the relay 10 to turn off. Then, the relay 10 performs an off operation and enters an open state. As a result, the voltage Vd3 becomes the same magnitude as the output voltage E(V) of the second power supply unit 95.

[0041] In this way, by maintaining the voltage applied to the load 92 at a value greater than Vs1(V), the operation of the load 92 can continue without stopping even if a ground fault occurs in the branch path B2. Therefore, it is not necessary to consider shortening the time from time T11 to time T12, and it is not necessary to use a relatively expensive semiconductor relay such as a MOSFET for the relay 10.

[0042] The first connection part C2 to which the branch path B1 is electrically connected is provided on the second conductive path 2 away from the load 92 compared to the first connection part C3. Therefore, if the resistance value of the resistance component of the power path 3 from the first connection part C2 to the second connection part C6 is set as the first resistance value R2y, the first resistance value R2y becomes a value larger than the first resistance value Ry (that is, Ry < R2y). Therefore, as shown in FIG. 4, when a ground fault occurs in the branch path B1, the voltage Vd3 becomes the voltage obtained by dividing the output voltage of the second power supply unit 95 by the second resistance value Rx and the first resistance value R2y. In this case, the value of the voltage Vd3 becomes larger compared to the case where a ground fault occurs in the branch path B2.

[0043] That is, in the protection area P1, when a ground fault occurs in the branch path B1 that is electrically connected to the first connection part C2 (end part) farther from the load 92 than the first connection part C3 (end part) closest to the load 92 among the first connection parts C2 and C3 (end parts) different from the first connection part C4 electrically connected to the relay 10, the load 92 can continue to operate.

[0044] In the second conductive path 2, the second connection part C7 is provided at a position closer to the second power supply unit 95 than the second connection part C6, and the second connection part C8 is provided at a position closer to the second power supply unit 95 than the second connection parts C6 and C7. As shown in FIG. 3, when a ground fault occurs in the branch path B2, the voltage at the second connection part C7 is Vd4 (hereinafter, also simply referred to as voltage Vd4), and the voltage at the second connection part C8 is Vd5 (hereinafter, also simply referred to as voltage Vd5). In this case, in the second conductive path 2, the closer to the second power supply unit 95 the position is, the larger the first resistance value Ry is, and the smaller the second resistance value Rx is. Therefore, the voltage Vd4 is larger than the voltage Vd3, and the voltage Vd5 is larger than the voltages Vd3 and Vd4 (i.e., Vd5>Vd4>Vd3). In other words, when a ground fault occurs on the first conductive path side, the voltage applied to the second connection part closer to the second power supply unit 95 is larger.

[0045] Here, the magnitude of the guaranteed operating voltage of the load 93 is Vs2 (V), and the magnitude of the guaranteed operating voltage of the load 94 is Vs3 (V). When the loads 93 and 94 are also loads to be protected in addition to the load 92, the positions of the second connection parts C6, C7, and C8 in the second conductive path 2 are appropriately changed according to the magnitude of the guaranteed operating voltages (Vs1, Vs2, and Vs3) of the loads 92, 93, and 94. This allows the operation of the loads 92, 93, and 94 to continue when a ground fault occurs at a position other than the protection region P1 on the first power supply unit 90 side.

[0046] For example, when Vs1(V) < Vs2(V) < Vs3(V), the load 94 with the largest operating guarantee voltage (Vs3(V)) is electrically connected to the second connection part C8 closest to the second power supply part 95. Then, the load 93 with the next largest operating guarantee voltage (Vs2(V)) is electrically connected to the second connection part C7 farther from the second power supply part 95 than the second connection part C8 to which the load 94 is electrically connected. And the load 92 with the smallest operating guarantee voltage (Vs1(V)) is electrically connected to the second connection part C6 farther from the second power supply part 95 than the second connection parts C7 and C8 to which the loads 93 and 94 are electrically connected. That is, when a plurality of protected loads are electrically connected to the second conductive path 2, the protected load with a large operating guarantee voltage is electrically connected to the second connection part closer to the second power supply part 95 than the protected load with a small operating guarantee voltage. And the protected load with a small operating guarantee voltage is electrically connected to the second connection part farther from the second power supply part 95 than the protected load with a large operating guarantee voltage.

[0047] Next, the effects of this configuration will be exemplified.

[0048] The protection device 70 is used in the power supply system 100 that supplies power to the loads 92, 93, and 94. The protection device 70 includes a power path 3 and a relay 10. The power path 3 has a first conductive path 1 electrically connected to the first power supply part 90 and a second conductive path 2 electrically connected to the second power supply part 95. The relay 10 switches between a permitted state that permits energization between the first conductive path 1 and the second conductive path 2 and a cutoff state that cuts off the energization. The first conductive path 1 is provided with first connection parts C2 and C3 where the branch paths B1 and B2 are detachable in a protection region P1 that is a predetermined range on the side of the first power supply part 90 from the relay 10. All of the first connection parts C2, C3, and C4 of the first conductive path 1 are covered by the protector 40, and in the protection region P1, the first conductive path 1 and the outside of the protector 40 are insulated by the protector 40. The second conductive path 2 has the load 92 (protected load) among the loads 92, 93, and 94 electrically connected thereto.

[0049] The first conductive path 1 of the protection device 70 is provided with first connection parts C2, C3 that are detachable in the protection area P1. All of the first connection parts C2, C3, C4 are covered by the protector 40. In the protection area P1, the first conductive path 1 and the outside of the protector 40 are insulated by the protector 40. This prevents a ground fault from occurring in the first connection parts C2, C3, C4, and makes it easy to keep the position where the ground fault occurs away from the load to be protected. Therefore, when a ground fault occurs in the first conductive path 1, the voltage applied to the load 92 (load to be protected) connected to the second conductive path 2 can be made difficult to drop due to the resistance component that the power path 3 originally has, and the operation of the load 92 can be made difficult to stop.

[0050] The first conductive path 1 of the protection device 70 has a protection area P1 continuously covered by the protector 40.

[0051] This configuration makes it possible to prevent a ground fault from occurring in the protection area P1, and to easily keep the position at which the ground fault occurs away from the load 92. Therefore, when a ground fault occurs in the first conductive path 1, the voltage applied to the load 92 connected to the second conductive path 2 is unlikely to drop due to the inherent resistance component of the power path 3, and the operation of the load 92 is unlikely to stop.

[0052] In the protection device 70, the resistance value of the power path 3 from the position (second connection part C6) where the load 92 (load to be protected) is electrically connected in the second conductive path 2 to the first connection part C3, which is the closest to the load 92 among the first connections C2, C3 different from the first connection part C4 connected to the relay 10 in the protection area P1, is a first resistance value Ry. The resistance value of the power path 3 from the second power supply part 95 to the position (second connection part C6) where the load 92 is electrically connected in the second conductive path 2 is a second resistance value Rx. When the output voltage of the second power supply part 95 is E and the guaranteed operating voltage of the load 92 is Vs1, the first resistance value Ry and the second resistance value Rx satisfy the formula 1. Rx / Ry≦(E-Vs1) / Vs1... formula 1

[0053] Even if a ground fault occurs from the load 92 (load to be protected) at the first connection C3, which is the closest to the load 92 among the first connections C2, C3 different from the first connection C4 connected to the relay 10 in the protection region P1, the voltage applied to the load 92 is equal to or higher than the guaranteed operation voltage (Vs1 (V)) of the load 92. For this reason, the protection device 70 can make it difficult to stop the operation of the load 92.

[0054] The second conductive path 2 of the protection device 70 is provided from the second power supply unit 95 to the relay 10, and the detachable second connection parts C5, C6, C7, C8, and C9 are covered by the protector 40. The protection device 70 has branch paths B3, B4, and B5 that electrically connect the loads 92, 93, and 94 to the second connection parts C6, C7, and C8. The branch paths B3, B4, and B5 have third connection parts Cb3, Cb4, and Cb5 that are electrically connected to the loads 92, 93, and 94 covered by the protector 40. With this configuration, the protection device 70 preferentially protects the second connection parts C5, C6, C7, C8, and C9 in the second conductive path 2 that are prone to ground faults. At the same time, the protection device 70 also preferentially protects the third connection parts Cb3, Cb4, and Cb5 of the branch paths B3, B4, and B5 electrically connected to the loads 92, 93, and 94. This makes it possible to effectively prevent a ground fault from occurring on the second conductive path 2 side.

[0055] The relay 10 of the protection device 70 is a mechanical relay. With this configuration, the protection device 70 can easily continue operation of the load 92 (load to be protected) without stopping it even if a ground fault occurs. This makes it possible to use a mechanical relay, which operates slower than a semiconductor relay, for the relay 10, and the use of a mechanical relay makes it easier to suppress increases in costs.

[0056] <Embodiment 2> An in-vehicle system 200 including a protection device 170 according to a second embodiment of the present disclosure will be described with reference to Fig. 5. The protection device 170 according to the second embodiment differs from the first embodiment in the form of a first protector 140A and a second protector 140B of a protector 140. The same components as those in the first embodiment are denoted by the same reference numerals, and a description of the same structures, actions, and effects as those in the first embodiment will be omitted.

[0057] The protector 140 has a first protector 140A and a second protector 140B. The first protector 140A and the second protector 140B are made of synthetic resin. The first protector 140A is an area including the first connection part C4 connected to the relay 10 and the first connection parts C2 and C3 connected to the branch paths B1 and B2, and intermittently covers a protection area P11 which is a predetermined range from the first connection part C4 to the first power supply unit 90 side. In the protection area P11 where the first protector 140A is provided, the first conductive path 1 and the outside of the first protector 140A are insulated by the first protector 140A. In the protection area P11 where the first protector 140A is not provided, the electric wires of the first conductive path 1 and the branch path B1 are insulated from the outside of the coating by the coating of the electric wires constituting the first conductive path 1 and the branch path B1.

[0058] The second protector 140B intermittently covers the second connection parts C5, C6, C7, C8, C9 and the third connection parts Cb3, Cb4, Cb5 electrically connected to the loads 92, 93, 94 as a protection area P12. In the protection area P12 where the second protector 140B is provided, the second conductive path 2 is insulated from the outside of the second protector 140B by the second protector 140B. In the protection area P12 where the second protector 140B is not provided, the wires of the first conductive path 1 and the branch paths B3, B4, B5 are insulated from the outside of the covering by the covering of the wires constituting the first conductive path 1 and the branch paths B3, B4, B5.

[0059] The protection device 170 is used in an in-vehicle system 200 that supplies power to loads 92, 93, and 94. The protection device 170 includes a power path 3 and a relay 10. The power path 3 includes a first conductive path 1 electrically connected to a first power supply unit 90 and a second conductive path 2 electrically connected to a second power supply unit 95. The relay 10 switches between an allowable state that allows current flow between the first conductive path 1 and the second conductive path 2 and a cut-off state that cuts off current flow. The first conductive path 1 is provided with first connection parts C2 and C3 to which the branch paths B1 and B2 are detachably attached in a protection area P11 that is a predetermined range from the relay 10 to the first power supply unit 90 side. The first conductive path 1 has first connection parts C2, C3, and C4 all covered by the protector 140, and the first conductive path 1 is insulated from the outside of the protector 140 by the protector 140 in the protection area P11. The second conductive path 2 is electrically connected to a load 92 (a load to be protected) out of loads 92, 93, and 94.

[0060] The first conductive path 1 of the protection device 170 is provided with first connection parts C2, C3 that are detachable in the protection area P11. All of the first connection parts C2, C3, C4 are covered by the protector 140. In the protection area P11, the first conductive path 1 and the outside of the protector 140 are insulated by the protector 140. This prevents a ground fault from occurring in the first connection parts C2, C3, C4, and makes it easy to keep the position where the ground fault occurs away from the load to be protected. Therefore, when a ground fault occurs in the first conductive path 1, the voltage applied to the load 92 connected to the second conductive path 2 can be made difficult to drop due to the resistance component that the power path 3 originally has, making it difficult to stop the operation of the load 92.

[0061] <Other embodiments> It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims.

[0062] In the first embodiment, the control unit 30 is mainly configured with a microcomputer, but it may be realized by a plurality of hardware circuits other than a microcomputer. In addition, at least one of the fault detection device and the detection unit may be provided separately from the control unit.

[0063] Unlike the first embodiment, a load may be connected to a branch path that is electrically connected to the first conductive path. In this case, the load connected to the first conductive path cannot be a load to be protected.

[0064] In the first embodiment, the output voltage of the first power supply unit 90 and the second power supply unit 95 is disclosed as 12 V, but the output voltage of the first power supply unit and the second power supply unit is not limited to this. Also, the output voltage of the first power supply unit and the second power supply unit may be different.

[0065] Unlike the first embodiment, the relay may be covered with a protector. For example, the first conductive path and the second conductive path may be continuously covered with the protector. [Explanation of symbols]

[0066] 1...First conductive path (power path) 2...Second conductive path (power path) 3…Power line 10...Relay (breaker) 30...Control section 40,140…Protector 40A, 140A...First protector 40B, 140B…Second protector 50...First voltage detection unit 51...Second voltage detection unit 70,170…Protective equipment 90...1st power supply section 92...Load (load to be protected) 93,94…Load 95...Second power supply section 100,200…Power supply system B1, B2...Fork B3, B4, B5... Branch paths (branch paths electrically connecting the load and the second connection part) C1, C2, C3...First connection part C4: First connection part (first connection part electrically connected to the interrupter part) C5,C6,C7,C8,C9...2nd connection part Cb1, Cb2…Third connection Cb3, Cb4, Cb5...Third connection (third connection electrically connected to the load) E…Output voltage P1, P11: Protection area (predetermined range from the connection part to the first power supply part side) P2,P12…Protection area Ry, R2y…First resistance value Rx: Second resistance value V1…First voltage V2: Second voltage Vd3, Vd4, Vd5…Voltage Vs, Vs1, Vs2, Vs3: Guaranteed operating voltage

Claims

1. A protection device for use in a power supply system that supplies power to a load, comprising: a power path including a first conductive path electrically connected to a first power supply unit and a second conductive path electrically connected to a second power supply unit; a cutoff unit that switches between a permissive state that permits current flow between the first conductive path and the second conductive path and a cutoff state that cuts off the current flow; Equipped with the first conductive path is provided with a first connection portion in a protection region that is a predetermined range from the interrupter to the first power supply unit side, the first connection portion is entirely covered with a protector, and the first conductive path is insulated from an outside of the protector by the protector in the protection region, a load to be protected among the loads is electrically connected to the second conductive path; a resistance value of the power path from a position to which the protected load is electrically connected in the second conductive path to an end portion of the protection area that is different from the first connection portion and is connected to the interrupter, the end portion being closest to the protected load, is a first resistance value Ry; a resistance value of the power path from the second power supply unit to a position on the second conductive path to which the protected load is electrically connected is a second resistance value Rx; The output voltage of the second power supply unit is E, When the guaranteed operating voltage of the load to be protected is Vs, A protection device, wherein the first resistance value Ry and the second resistance value Rx satisfy Equation 1. Rx / Ry≦(E-Vs) / Vs...Formula 1

2. The protection device according to claim 1 , wherein the first conductive path has the protection region continuously covered by the protector.

3. The second conductive path has a second connection portion provided between the second power supply portion and the interrupter portion, the second connection portion being covered by the protector, a branch path electrically connecting the load and the second connection portion, 3. The protection device according to claim 1, wherein the branch path has a third connection portion electrically connected to the load, the third connection portion being covered by the protector.

4. The protection device according to claim 1 , wherein the interrupter is a mechanical relay.

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