Ignition circuit and breaker system

Abstract

The present disclosure addresses the problem of preventing, in the case of momentary overcurrent, a squib from operating. An ignition circuit (1) is electrically connected to a breaker (8). The breaker (8) comprises: a first terminal (81); a second terminal (82) that is electrically connected to the first terminal (81); a squib (83) that is electrically connected to the ignition circuit (1) and contains an explosive to be ignited by the ignition circuit (1); and a projectile (84) that obtains propulsive force by combustion of the explosive and breaks the electrical connection between the first terminal (81) and the second terminal (82). The ignition circuit (1) comprises a first switch circuit (31) and a delay circuit (32). The first switch circuit (31) is electrically connected to the squib (83) and, when an input voltage is equal to or more than a threshold value, supplies electricity to the squib (83). The delay circuit (32) is electrically connected to the squib (83) via the first switch circuit (31) and delays the supply of the electricity to the squib (83) via the first switch circuit (31).

Description

Ignition circuit and shutoff system

[0001] The present disclosure relates to an ignition circuit and a shutoff system.

[0002] Patent Document 1 discloses an electrical system including an electrical circuit and an electrical switching device electrically connected to the electrical circuit to open or close the electrical circuit. The electrical switching device includes at least two fixed contacts, a movable contact, a levitation actuator, and a pyrotechnic device. The movable contact is configured to operate in a first position where the movable contact is in electrical contact with the fixed contacts and in a second position where the movable contact is not in electrical contact with the fixed contacts. The levitation actuator is located above the movable contact or one of the fixed contacts. The levitation actuator separates the movable contact and at least one of the fixed contacts when the movable contact is in the first position and a threshold current passes through the fixed contact and the movable contact. The pyrotechnic device moves the movable contact from the first position to the second position.

[0003] Special Publication No. 2023-535020

[0004] In the above configuration, even if a momentary overcurrent flows through the electrical circuit that is not large enough to damage the relays and loads connected to the electrical circuit, the pyrotechnic device may be activated and the electrical circuit may be cut off.

[0005] An object of the present disclosure is to provide an ignition circuit and a cutoff system that can prevent the squib from operating in the event of a momentary overcurrent.

[0006] An ignition circuit according to one aspect of the present disclosure is electrically connected to a circuit breaker. The circuit breaker includes a first terminal, a second terminal, a squib, and a projectile. The second terminal is electrically connected to the first terminal. The squib is electrically connected to the ignition circuit. The squib contains a gunpowder that is ignited by the ignition circuit. The projectile obtains thrust through combustion of the gunpowder and interrupts the electrical connection between the first terminal and the second terminal. The ignition circuit includes a first switch circuit and a delay circuit. The first switch circuit is electrically connected to the squib. The first switch circuit supplies power to the squib when an input voltage is equal to or greater than a threshold. The delay circuit is electrically connected to the squib via the first switch circuit. The delay circuit delays the supply of power to the squib via the first switch circuit.

[0007] A circuit breaker system according to one aspect of the present disclosure includes the ignition circuit and the circuit breaker.

[0008] FIG. 1 is a block diagram of an interruption system of a first embodiment in a state before fracture. FIG. 2 is a block diagram of the interruption system of the same in a state after fracture. FIG. 3 is a cross-sectional view of a circuit breaker provided in the same interruption system. FIG. 4 is a graph showing the interruption characteristics of the same interruption system. FIG. 5 is a block diagram of an interruption system of a second embodiment. FIG. 6 is an example of a circuit diagram of the same interruption system. FIG. 7 is a block diagram of an interruption system of a third embodiment. FIG. 8 is an example of a circuit diagram of the same interruption system. FIG. 9 is a graph showing the output characteristics of a magnetic sensor provided in the same interruption system. FIG. 10 is a block diagram of an interruption system of a fourth embodiment. FIG. 11 is a block diagram of an interruption system of a fifth embodiment. FIG. 12 is a block diagram of an interruption system of a sixth embodiment. FIG. 13 is an example of a circuit diagram of the same interruption system. FIG. 14 is a block diagram of an interruption system of a seventh embodiment. FIG. 15 is an example of a circuit diagram of the same interruption system. FIG. 16 is a block diagram of an interruption system of an eighth embodiment. FIG. 17 is an example of a circuit diagram of the same interruption system. Fig. 18 is a graph showing output characteristics of a first magnetic sensor and a second magnetic sensor provided in the isolation system of the same. Fig. 19 is an example of a circuit diagram of the isolation system of embodiment 9. Fig. 20 is a graph showing output characteristics of a magnetic sensor provided in the isolation system of the same. Fig. 21 is an example of a circuit diagram of the isolation system of embodiment 10. Fig. 22 is an example of a circuit diagram of the isolation system of embodiment 11. Fig. 23 is an explanatory diagram for explaining the arrangement of the first magnetic sensor and the second magnetic sensor provided in the isolation system of the same. Fig. 24 is a graph showing output characteristics of the first magnetic sensor and the second magnetic sensor of the same. Fig. 25 is an example of a circuit diagram of the isolation system of embodiment 12. Fig. 26 is a block diagram of the isolation system of embodiment 13. Fig. 27 is a flowchart showing the operation of the isolation system of the same.

[0009] Hereinafter, an isolation system according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. However, the following embodiments are merely a portion of various embodiments of the present disclosure. The following embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. The following embodiments and modified examples may be combined as appropriate. Furthermore, the drawings described in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios.

[0010] (1) First Embodiment An ignition circuit 1 and a cutoff system 100 according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0011] (1.1) Interruption System Fig. 1 is a block diagram of an interruption system 100 in a state before the main electric line 9 is broken. Fig. 2 is a block diagram of the interruption system 100 in a state after the main electric line 9 is broken.

[0012] The interruption system 100 is mounted on an object. The object is a device having a main electric circuit 9 through which current supplied from a power source 91 to a load 92 passes. The interruption system 100 is a system that is activated, for example, when an overcurrent flows in the main electric circuit 9 inside the object, to interrupt the main electric circuit 9. In addition to the interruption system 100, a relay 93 that can switch the main electric circuit 9 between conduction and interruption can be connected to the main electric circuit 9 (see FIGS. 1 and 2).

[0013] The object on which the interruption system 100 is mounted is, for example, a vehicle. In this case, the load 92 may be a motor mounted on the vehicle, and the power source 91 may be a battery (e.g., a lithium-ion battery) for driving the motor. The interruption system 100 interrupts the electrical connection between the motor and the battery by interrupting the main electric circuit 9 in an emergency, such as a vehicle abnormality or accident. Note that the object may be an object other than a vehicle, and examples include, but are not limited to, home appliances and solar power generation systems.

[0014] As shown in FIG. 1 , the circuit breaker system 100 includes a circuit breaker 8 and an ignition circuit 1 .

[0015] (1.2) Circuit Breaker The circuit breaker 8 is electrically connected to the ignition circuit 1. In this disclosure, "the first member and the second member are electrically connected" means that the first member and the second member are connected directly or via a third member so that electricity can flow from one of the first member and the second member to the other. In this embodiment, the circuit breaker 8 and the ignition circuit 1 are connected by a cable.

[0016] 1 , the circuit breaker 8 includes a first terminal 81, a second terminal 82, a squib 83, and a projectile 84. The first terminal 81 is electrically connected to the main electric circuit 9. The second terminal 82 is electrically connected to the first terminal 81.

[0017] 1 to 3, the circuit breaker 8 further includes a conductor 85 and a housing 86. The second terminal 82 is electrically connected to the first terminal 81 via the conductor 85. The conductor 85 may, for example, be integral with a bus bar that constitutes the main electrical path 9. The second terminal 82 is electrically connected to the main electrical path 9. As shown in FIG. 3, the housing 86 holds or houses the squib 83, the projectile 84, and the conductor 85.

[0018] As shown in FIGS. 1 to 3 , the squib 83 is electrically connected to the ignition circuit 1. As shown in FIG. 3 , the squib 83 includes a heating element 833 and explosives 834. The heating element 833 is, for example, a nichrome wire or an alloy wire of iron, chromium, and aluminum. The heating element 833 is electrically connected between a first end 831 and a second end 832 of the squib 83. The heating element 833 generates heat when a current flows through the heating element 833. The explosives 834 are disposed around the heating element 833. The explosives 834 are ignited by the heat generated by the heating element 833. Because a current is supplied to the heating element 833 from the ignition circuit 1, it can be said that the explosives 834 are ignited by the ignition circuit 1. In this way, the squib 83 includes the explosives 834 that are ignited by the ignition circuit 1.

[0019] When the gunpowder 834 is ignited in the squib 83, a large amount of gas is generated by the combustion of the gunpowder 834. The generated gas is released into an internal space 860 of a housing 86 in which the squib 83 is housed.

[0020] 3 , the projectile 84 is disposed in an internal space 860 of the housing 86. The projectile 84 is disposed in the internal space 860 of the housing 86 at a position between the squib 83 and the conductor 85. The projectile 84 is held by a holding portion 861 provided in the housing 86. The projectile 84 is held by the holding portion 861 so as to face the conductor 85. In this case, the holding portion 861 is the inner surface of the housing 86, but may have a protrusion or the like that protrudes from the inner surface of the housing 86 and holds the projectile 84.

[0021] The projectile 84 is ejected from the holder 861 and moves due to the pressure of the gas generated in the squib 83. The projectile 84 ejected from the holder 861 moves toward the conductor 85 and separates the conductor 85 from the first terminal 81 and the second terminal 82 (see FIG. 2 ). This cuts off the electrical connection between the first terminal 81 and the second terminal 82. In this way, the projectile 84 obtains impetus from the combustion of the gunpowder 834 in the squib 83, and cuts off the electrical connection between the first terminal 81 and the second terminal 82.

[0022] Thus, in the circuit breaker 8 of this embodiment, when power (sufficient to ignite the explosive 834) is supplied from the ignition circuit 1 to the squib 83, the explosive 834 in the squib 83 is ignited. The projectile 84 obtains thrust from the combustion of the explosive 834 in the squib 83, and disconnects the conductor 85 from at least one of the first terminal 81 and the second terminal 82. This interrupts the main electric circuit 9.

[0023] However, the configuration of the circuit breaker 8 is not limited to this. In one modified circuit breaker 8, the conductor 85 is separate from at least one of the first terminal 81 and the second terminal 82. The conductor 85 has a movable contact, and the first terminal 81 (or the second terminal 82) has a fixed contact that comes into contact with the movable contact. In the circuit breaker 8 of one modified example, the projectile 84, which gains impetus from the combustion of the gunpowder 834 in the squib 83, is configured to enter between the movable contact and the fixed contact. This can interrupt the electrical connection between the first terminal 81 and the second terminal 82.

[0024] (1.3) Ignition Circuit As shown in FIG. 1, the ignition circuit 1 includes a starter circuit 21, a switch circuit (hereinafter also referred to as a “first switch circuit”) 31, and a delay circuit 32.

[0025] The starter circuit 21 generates power using the energy of the current Ip flowing in the main current path 9 (the intermediate current path 90 in FIG. 1 ). The starter circuit 21 is electrically connected to the squib 83 via the delay circuit 32 and the first switch circuit 31.

[0026] The first switch circuit 31 is electrically connected to the squib 83. Power is supplied to the first switch circuit 31 from the start-up circuit 21 via the delay circuit 32. The first switch circuit 31 is turned on when the input voltage is equal to or higher than a threshold. That is, the first switch circuit 31 supplies power to the squib 83 when the input voltage is equal to or higher than the threshold. Power is supplied to the squib 83 from the start-up circuit 21.

[0027] The delay circuit 32 is electrically connected to the squib 83 via the first switch circuit 31. The delay circuit 32 is also electrically connected to the starter circuit 21.

[0028] The delay circuit 32 delays the supply of power from the starter circuit 21 to the first switch circuit 31. That is, the delay circuit 32 delays the supply of power to the squib 83 via the first switch circuit 31. The delay circuit 32 includes, for example, a capacitor. The delay circuit 32 delays the supply of power to the squib 83 via the first switch circuit 31 by a delay time that corresponds to the magnitude (current value) of the current Ip flowing through the main electric circuit 9.

[0029] In the interruption system 100 of this embodiment, the power generated by the starting circuit 21 is supplied to the squib 83 after the delay time set by the delay circuit 32 has elapsed. The delay time set by the delay circuit 32 becomes shorter as the magnitude of the current Ip flowing through the main electric circuit 9 increases. That is, if the current Ip flowing through the main electric circuit 9 is an overcurrent with a relatively large current value, the delay time set by the delay circuit 32 becomes shorter, and if the current Ip is an overcurrent with a relatively small current value, the delay time set by the delay circuit 32 becomes longer. Therefore, if a small overcurrent (e.g., 2 kA) flows through the main electric circuit 9 for a relatively long time, power is supplied from the ignition circuit 1 to the squib 83 after the long delay time set by the delay circuit 32, thereby activating the squib 83. On the other hand, if a large overcurrent (e.g., 10 kA) flows through the main electric circuit 9, power is supplied from the ignition circuit 1 to the squib 83 after the short delay time set by the delay circuit 32, thereby activating the squib 83 immediately. Furthermore, if an overcurrent of a small current value flows momentarily, but is not large enough to cause damage to the relay 93 and the load 92, the vehicle control unit or the like can turn off the relay 93 and interrupt the main circuit 9 during the long delay time provided by the delay circuit 32, thereby preventing the squib 83 from operating.

[0030] The circuit breaking system 100 of this embodiment can achieve the circuit breaking characteristics shown in Fig. 4. The "trip current" on the horizontal axis of Fig. 4 indicates the magnitude of the current value of the overcurrent flowing through the main electric circuit 9. The "operation time" on the vertical axis of Fig. 4 indicates the time from when the overcurrent starts to flow through the main electric circuit 9 to when the squib 83 of the circuit breaker 8 is ignited. As shown in Fig. 4, in the circuit breaking system 100, when an overcurrent with a large current value flows through the main electric circuit 9, the circuit breaker 8 operates in a relatively short time. On the other hand, when an overcurrent with a small current value flows through the main electric circuit 9, the circuit breaker 8 operates after a relatively long time has elapsed.

[0031] (2) Second Embodiment The interruption system 100 of the second embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a block diagram of the interruption system 100 of the second embodiment in a state before the main electric line 9 is broken. Fig. 6 shows an example of a circuit diagram of the second embodiment.

[0032] As shown in FIG. 5 , the ignition circuit 1 of the present embodiment further includes a switch circuit (hereinafter also referred to as a “second switch circuit”) 33, a switch circuit (hereinafter also referred to as a “third switch circuit”) 22, and a storage circuit 23, in addition to the first switch circuit 31, the delay circuit 32, and the starter circuit 21 that are included in the ignition circuit 1 of the first embodiment.

[0033] (2.1) Starting Circuit As shown in FIGS. 5 and 6 , the starting circuit 21 of this embodiment includes a coil 211. This coil 211 generates a voltage for power supplied to the squib 83 by electromagnetic induction in response to changes in the current Ip flowing through the main electric circuit 9 (the intermediate electric circuit 90 in FIG. 5 ). For example, the coil 211 is wound around a core (yoke). The core is, for example, hollow and cylindrical, and the main electric circuit 9 (the intermediate electric circuit 90) is disposed so as to pass through it. The coil 211, the core, and the main electric circuit 9 constitute a transformer.

[0034] The power generated by the voltage generated by the coil 211 is supplied to the first switch circuit 31 via the delay circuit 32. That is, in the interruption system 100 of the present embodiment, the squib 83 is supplied with power generated by the voltage generated by the coil 211 of the starting circuit 21.

[0035] 6 , the start-up circuit 21 further includes a diode (rectifier circuit) 212 and a resistor 213. A parallel circuit of the diode 212 and the resistor 213 is electrically connected across the coil 211. The cathode of the diode 212 is connected to a first end of the coil 211, and the anode of the diode 212 is connected to a second end of the coil 211.

[0036] (2.2) Third Switch Circuit The third switch circuit 22 is electrically connected to the start-up circuit 21. The third switch circuit 22 is electrically connected between the start-up circuit 21 and the storage circuit 23.

[0037] As shown in FIG. 6, the third switch circuit 22 includes a thyristor 221 , a diode 222 , a Zener diode 223 , a resistor 224 , and a capacitor 225 .

[0038] The anode of the thyristor 221 is electrically connected to the starter circuit 21. The cathode of the thyristor 221 is electrically connected to the storage circuit 23.

[0039] The cathodes of the diode 222 and the Zener diode 223 are electrically connected to each other. The anode of the diode 222 is electrically connected to the anode of the thyristor 221. The anode of the Zener diode 223 is electrically connected to the gate of the thyristor 221.

[0040] A parallel circuit of a resistor 224 and a capacitor 225 is electrically connected between the gate and cathode of the thyristor 221 .

[0041] In the third switch circuit 22, when a voltage equal to or greater than the threshold voltage is applied to the third switch circuit 22, a current flows to the gate of the thyristor 221, turning on the thyristor 221. This turns on the third switch circuit 22.

[0042] The third switch circuit 22 is off when the voltage generated in the starter circuit 21 is below the threshold voltage, and is on when the voltage is equal to or greater than the threshold voltage. The presence of the third switch circuit 22 prevents power from being supplied from the starter circuit 21 to the first switch circuit 31 when the voltage generated in the starter circuit 21 is below the threshold voltage. This makes it possible to prevent the squib 83 from operating when an overcurrent of a small current value that does not cause damage to the relay 93, load 92, etc., flows momentarily through the main electric circuit 9.

[0043] (2.3) Storage Circuit As shown in Fig. 5, the storage circuit 23 is electrically connected to the third switch circuit 22. The storage circuit 23 is electrically connected between the third switch circuit 22 and the second switch circuit 33. The storage circuit 23 stores the power from the starter circuit 21.

[0044] As shown in FIG. 6 , the power storage circuit 23 includes a capacitor 231 and a resistor 232 .

[0045] A first end of the capacitor 231 is electrically connected to the cathode of the thyristor 221 of the third switch circuit 22. A second end of the capacitor 231 is electrically connected to the anode of the diode 212 of the start-up circuit 21. The resistor 232 is electrically connected across the capacitor 231.

[0046] 5, the delay circuit 32 is electrically connected to the first switch circuit 31. The delay circuit 32 is electrically connected between the storage circuit 23 and the first switch circuit 31 via the second switch circuit 33.

[0047] As shown in FIG. 6, the delay circuit 32 includes resistors 321 and 322 and a capacitor 323 .

[0048] A series circuit of a resistor 321 and a capacitor 323 is electrically connected across both ends of the capacitor 231 of the power storage circuit 23 via the second switch circuit 33. A first end of the resistor 321 is electrically connected to a first end of the capacitor 231, a second end of the resistor 321 is electrically connected to a first end of the capacitor 323, and a second end of the capacitor 323 is electrically connected to a second end of the capacitor 231.

[0049] The resistor 322 is electrically connected across the capacitor 323 .

[0050] The delay circuit 32 delays the timing at which power is supplied from the start-up circuit 21 to the first switch circuit 31 (i.e., the on timing of the first switch circuit 31 ) by a delay time corresponding to the charging time of the capacitor 323 .

[0051] 5, the first switch circuit 31 is electrically connected to the squib 83. The first switch circuit 31 is electrically connected between the delay circuit 32 and the squib 83.

[0052] As shown in FIG. 6, the first switch circuit 31 includes a thyristor 311 , a diode 312 , a Zener diode 313 , a resistor 314 , a capacitor 315 , and a transistor 316 .

[0053] The anode of the thyristor 311 is electrically connected to the power storage circuit 23 via the second switch circuit 33. The cathode of the thyristor 311 is electrically connected to the squib 83.

[0054] The collector of the transistor 316 is electrically connected to a first end of the resistor 321 of the delay circuit 32. The base of the transistor 316 is electrically connected to a connection point between the resistor 321 and the capacitor 323 of the delay circuit 32. The emitter of the transistor 316 is electrically connected to the anode of the diode 312.

[0055] The cathodes of the diode 312 and the Zener diode 313 are electrically connected to each other. The anode of the diode 312 is electrically connected to the anode of the thyristor 311 via the transistor 316. The anode of the Zener diode 313 is electrically connected to the gate of the thyristor 311.

[0056] A parallel circuit of a resistor 314 and a capacitor 315 is electrically connected between the gate and cathode of the thyristor 311 .

[0057] In the first switch circuit 31, when the voltage across the capacitor 323 of the delay circuit 32 becomes equal to or higher than the threshold voltage for turning on the transistor 316, a current flows to the gate of the thyristor 311, turning on the thyristor 311. This turns on the first switch circuit 31.

[0058] (2.6) Second Switch Circuit As shown in Fig. 5 , the second switch circuit 33 is electrically connected to the storage circuit 23. The second switch circuit 33 is electrically connected between the storage circuit 23 and the delay circuit 32. That is, the second switch circuit 33 is electrically connected to the first switch circuit 31 via the delay circuit 32. The second switch circuit 33 is also electrically connected between the start-up circuit 21 and the delay circuit 32. Since the delay circuit 32 is connected between the first switch circuit 31 and the second switch circuit 33, the delay circuit 32 delays the supply of power from the second switch circuit 33 to the first switch circuit 31, thereby delaying the supply of power to the squib 83 via the first switch circuit 31.

[0059] 6, the second switch circuit 33 includes, for example, a reed switch 331. The reed switch 331 is disposed in an electromagnetic field generated by the current Ip flowing through the main electric circuit 9.

[0060] The second switch circuit 33 (reed switch 331) is maintained off when the value of the current Ip flowing through the main electric circuit 9 is small. On the other hand, when an overcurrent flows through the main electric circuit 9, the second switch circuit 33 is turned on by the magnetic field generated by the overcurrent and outputs power from the starting circuit 21 to the delay circuit 32. However, if the value of the current Ip flowing through the main electric circuit 9 subsequently decreases, the second switch circuit 33 is turned off again. In other words, even if the second switch circuit 33 is turned on when an overcurrent flows through the main electric circuit 9, the second switch circuit 33 is turned off if the overcurrent ends in a short period of time. Therefore, if the overcurrent is relatively small and lasts for a short period of time such that the capacitor 323 of the delay circuit 32 is not sufficiently charged while the second switch circuit 33 is on, the first switch circuit 31 is maintained off without being turned on.

[0061] The ignition circuit 1 of this embodiment includes the second switch circuit 33, so even if an overcurrent flows in the main current circuit 9, if the overcurrent is momentary, power is not supplied from the ignition circuit 1 to the squib 83. This makes it possible to prevent the squib 83 from operating if a small overcurrent flows momentarily that does not damage the relay 93, load 92, etc.

[0062] (2.7) First Circuit Hereinafter, for convenience, a circuit including the second switch circuit 33, the delay circuit 32, and the first switch circuit 31 may be referred to as the "first circuit 3" (see FIG. 5). When a magnetic field of a strength sufficient to turn on the second switch circuit 33 is applied to the second switch circuit 33 and a voltage sufficient to turn on the first switch circuit 31 is applied to the first switch circuit 31, the first circuit 3 becomes conductive and supplies power from the start-up circuit 21 to the squib 83. The first circuit 3 is required to include at least the delay circuit 32 and the first switch circuit 31, and does not necessarily have to include the second switch circuit 33.

[0063] 5 , the third switch circuit 22 is electrically connected between the starter circuit 21 and the first circuit 3. In addition, the storage circuit 23 is electrically connected between the third switch circuit 22 and the first circuit 3.

[0064] (3) Embodiment 3 The interruption system 100 of this embodiment will be described with reference to Figures 7 to 9. Figure 7 is a block diagram of the interruption system 100 of this embodiment in a state before the main electric circuit 9 is broken. Figure 8 shows an example of a circuit diagram of this embodiment. Figure 9 shows the characteristics of the output voltage Vs0 of the magnetic sensor 421 provided in the ignition circuit 1.

[0065] As shown in Fig. 7, the ignition circuit 1 of this embodiment includes, in addition to the elements of the ignition circuit 1 of the second embodiment (see Fig. 5), a second circuit 4. The second circuit 4 is electrically connected in parallel with the first circuit 3.

[0066] (3.1) Second Circuit The second circuit 4 supplies power to the squib 83 when a large overcurrent flows through the main current circuit 9. In this embodiment, the second circuit 4 becomes conductive when a large overcurrent flows through the main current circuit 9, and supplies the power output from the starting circuit 21 and stored in the storage circuit 23 to the squib 83.

[0067] As described above, the first circuit 3 also supplies power to the squib 83 when an overcurrent flows in the main electric circuit 9. However, because the first circuit 3 includes the delay circuit 32, the time (referred to as the "first time") from when an overcurrent flows in the main electric circuit 9 to when power is supplied to the squib 83 via the first circuit 3 is relatively long. The first time is, for example, about 100 ms.

[0068] On the other hand, the second circuit 4 does not include a delay circuit, and the time (referred to as the "second time") from when an overcurrent flows in the main current circuit 9 to when power is supplied to the squib 83 via the second circuit 4 is shorter than the first time. The second time is not particularly limited, but is, for example, about several ms or less.

[0069] However, the second circuit 4 supplies power to the squib 83 when a large overcurrent flows through the main electric circuit 9, but does not supply power to the squib 83 when a small overcurrent flows through the main electric circuit 9. In other words, the threshold current value (first current threshold) of the current Ip flowing through the main electric circuit 9, which is necessary to supply power to the squib 83 via the second circuit 4, is greater than the threshold current value (second current threshold) of the current Ip flowing through the main electric circuit 9, which is necessary to supply power to the squib 83 via the first circuit 3 (first current threshold<second current threshold).

[0070] In other words, when a large overcurrent flows through the main current circuit 9 (i.e., when a predetermined condition is satisfied), the second circuit 4 of this embodiment supplies power to the squib 83 at an earlier timing than the first circuit 3. The interruption characteristics of the second circuit 4 can be said to correspond, for example, to the region near the right end of the graph in FIG.

[0071] In the circuit breaking system 100 of this embodiment, if an overcurrent with a small current value flows for a relatively long time through the main electric circuit 9, the first circuit 3 can activate the squib 83. Also, if an overcurrent with a large current value flows through the main electric circuit 9, the second circuit 4 can instantly activate the squib 83. Furthermore, if an overcurrent with a small current value that does not damage the relay 93, load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor 323 of the delay circuit 32 of the first circuit 3 is not sufficiently charged and the second circuit 4 is not turned on, preventing the activation of the squib 83.

[0072] As shown in FIG. 7 , the second circuit 4 of this embodiment includes a magnetic sensor 421. The magnetic sensor 421 is disposed in an electromagnetic field generated by the current Ip flowing through the main electric circuit 9. The second circuit 4 supplies power to the squib 83 when the strength of the magnetic field applied to the magnetic sensor 421 is equal to or greater than a certain strength (hereinafter also referred to as the “strength threshold Hth0”). For example, as shown in FIG. 9 , the magnetic sensor 421 outputs a low-level voltage VL when the strength of the magnetic field applied to the magnetic sensor 421 is equal to or greater than the strength threshold Hth0, and outputs a high-level voltage VH (>VL) when the strength of the magnetic field applied to the magnetic sensor 421 is less than the strength threshold Hth0. By utilizing the magnetic sensor 421, when a large overcurrent flows through the main electric circuit 9, the second circuit 4 is energized, thereby enabling the squib 83 to be activated more quickly than if it were activated via the first circuit 3.

[0073] More specifically, as shown in FIG. 8 , the second circuit 4 includes a power supply circuit 41, a switch circuit (hereinafter also referred to as a “fourth switch circuit”) 42, and a switch circuit (hereinafter also referred to as a “fifth switch circuit”) 43.

[0074] (3.2) Power Supply Circuit The power supply circuit 41 includes a Zener diode 411 , a resistor 412 , and a capacitor 413 .

[0075] The series circuit of the Zener diode 411 and the resistor 412 is electrically connected across the capacitor 231 of the storage circuit 23. A first end of the resistor 412 is electrically connected to the first end of the capacitor 231 of the storage circuit 23, a second end of the resistor 412 is electrically connected to the cathode of the Zener diode 411, and an anode of the Zener diode 411 is electrically connected to the second end of the capacitor 231 of the storage circuit 23.

[0076] The capacitor 413 is electrically connected between the cathode and anode of the Zener diode 411 .

[0077] The power supply circuit 41 generates operating power for the magnetic sensor 421 using the power stored in the capacitor 231 of the power storage circuit 23 .

[0078] (3.3) Fourth Switch Circuit The fourth switch circuit 42 includes a magnetic sensor 421 , resistors 422 , 423 , and 424 , and a transistor 425 .

[0079] The magnetic sensor 421 is electrically connected to the power supply circuit 41 and operates using operating power supplied from the power supply circuit 41 .

[0080] As described above, the magnetic sensor 421 is disposed in the electromagnetic field generated by the current Ip flowing through the main current circuit 9. As shown in Fig. 9 , the magnetic sensor 421 outputs a high-level voltage VH when the strength of the magnetic field applied to the magnetic sensor 421 is less than the strength threshold Hth0, and outputs a low-level voltage VL (<VH) when the strength of the magnetic field applied to the magnetic sensor 421 is equal to or greater than the strength threshold Hth0. The magnetic sensor 421 is, for example, an NPN open-collector output sensor.

[0081] The magnetic sensor 421 includes a Hall element, a GMR element, or an AMR element. When the magnetic sensor 421 includes a Hall element, a GMR element, or an AMR element, the second time period is shorter than 1 ms.

[0082] A first end of the resistor 422 is electrically connected to a first end of the capacitor 231 of the storage circuit 23, a second end of the resistor 422 is electrically connected to a first end of the resistor 423, and a second end of the resistor 423 is electrically connected to a second end of the capacitor 231 of the storage circuit 23. The connection point between the second end of the resistor 422 and the first end of the resistor 423 is electrically connected to the output end of the magnetic sensor 421.

[0083] The connection point between the second end of the resistor 422 and the first end of the resistor 423 is electrically connected to the base of the transistor 425. The first end of the resistor 424 is electrically connected to the first end of the resistor 422. The second end of the resistor 424 is electrically connected to the collector of the transistor 425. The emitter of the transistor 425 is electrically connected to the second end of the resistor 423.

[0084] In the fourth switch circuit 42, when the strength of the magnetic field applied to the magnetic sensor 421 is less than the strength threshold Hth0, the transistor 425 is turned on, and when the strength of the magnetic field applied to the magnetic sensor 421 is greater than or equal to the strength threshold Hth0, the transistor 425 is turned off.

[0085] 8, the fifth switch circuit 43 is electrically connected to the fourth switch circuit 42. The fifth switch circuit 43 is electrically connected between the fourth switch circuit 42 and the squib 83.

[0086] As shown in FIG. 8, the fifth switch circuit 43 includes a thyristor 431 , a Zener diode 433 , a resistor 434 , a capacitor 435 , and a transistor 436 .

[0087] The anode of the thyristor 431 is electrically connected to the first end of the resistor 424 of the fourth switch circuit 42. The cathode of the thyristor 431 is electrically connected to the squib 83.

[0088] The collector of the transistor 436 is electrically connected to the first end of the resistor 424 of the fourth switch circuit 42. The base of the transistor 436 is electrically connected to the connection point between the second end of the resistor 424 of the fourth switch circuit 42 and the collector of the transistor 425. The emitter of the transistor 436 is electrically connected to the cathode of the Zener diode 433. The anode of the Zener diode 433 is electrically connected to the gate of the thyristor 431.

[0089] A parallel circuit of a resistor 434 and a capacitor 435 is electrically connected between the gate and cathode of the thyristor 431 .

[0090] In the fifth switch circuit 43, when the strength of the magnetic field applied to the magnetic sensor 421 is less than the strength threshold Hth0 and the transistor 425 of the fourth switch circuit 42 is turned on, the transistor 436 and the thyristor 431 are turned off, thereby turning off the fifth switch circuit 43.

[0091] In the fifth switch circuit 43, when the strength of the magnetic field applied to the magnetic sensor 421 is equal to or greater than the strength threshold Hth0 and the transistor 425 of the fourth switch circuit 42 is turned off, the voltage across the capacitor 231 of the storage circuit 23 is applied to the transistor 436 and the Zener diode 433. If the voltage across the capacitor 231 of the storage circuit 23 is equal to or greater than the threshold voltage for turning on the transistor 436, a current flows to the gate of the thyristor 431, turning on the thyristor 431. This turns on the fifth switch circuit 43, and power is supplied to the squib 83 via the second circuit 4.

[0092] In the interruption system 100 of the present embodiment, the fourth switch circuit 42 may include a reed switch instead of the magnetic sensor 421, the resistors 422 to 424, and the transistor 425. In this case, the second time period is, for example, about 1 to 2 ms. In this case, the power supply circuit 41 and the transistor 436 of the fifth switch circuit 43 may be omitted.

[0093] (4) Fourth Embodiment The interruption system 100 of this embodiment will be described with reference to Fig. 10. Fig. 10 is a block diagram of the interruption system 100 of this embodiment in a state before the main electric line 9 is broken.

[0094] 10, in the ignition circuit 1 of the present embodiment, the starting circuit 21 in the ignition circuit 1 of the second embodiment (see FIG. 5) includes a switch 214 instead of the coil 211. That is, the starting circuit 21 includes the switch 214 connected between the main current path 9 and the delay circuit 32.

[0095] The switch 214 of the starter circuit 21 is turned on when an overcurrent flows in the main electric circuit 9. The switch 214 of the starter circuit 21 is, for example, a reed switch that is placed in an electromagnetic field generated by the current Ip flowing in the main electric circuit 9.

[0096] When the switch 214 of the starter circuit 21 is turned on, the starter circuit 21 supplies (a portion of) the current Ip flowing in the main electric circuit 9 to the first circuit 3 (delay circuit 32) via the third switch circuit 22. That is, in the interruption system 100 of the present embodiment, when an overcurrent flows in the main electric circuit 9, the switch 214 of the starter circuit 21, the third switch circuit 22, the second switch circuit 33, and the first switch circuit 31 are turned on, and (a portion of) the current Ip flowing in the main electric circuit 9 can be supplied to the squib 83.

[0097] In this embodiment, it is possible to omit the first switch circuit 31, and / or the second switch circuit 33, and / or the third switch circuit 22. Furthermore, instead of a reed switch, a relay, a semiconductor relay, a transistor, a MOS-FET, or the like may be used as the switch 214 of the starter circuit 21.

[0098] The interruption system 100 of this embodiment may also include the second circuit 4 (power supply circuit 41, fourth switch circuit 42, and fifth switch circuit 43) of the third embodiment.

[0099] (5) Fifth Embodiment The interruption system 100 of this embodiment will be described with reference to Fig. 11. Fig. 11 is a block diagram of the interruption system 100 of this embodiment in a state before the main electric line 9 is broken.

[0100] As shown in Fig. 11 , the ignition circuit 1 of this embodiment further includes a second circuit 4 in addition to the elements of the ignition circuit 1 of embodiment 4 (see Fig. 10 ). If the starter circuit 21 of the ignition circuit 1 of embodiment 4 is defined as the "first starter circuit 21," the second circuit 4 includes a second starter circuit 44 that is different from the first starter circuit 21. In other words, the ignition circuit 1 further includes the second starter circuit 44 that is electrically connected to the squib 83 without passing through the delay circuit 32.

[0101] 11 , the second starting circuit 44 includes a switch 441 connected between the main electric circuit 9 and the squib 83. The switch 441 of the second starting circuit 44 is turned on when an overcurrent flows in the main electric circuit 9. The switch 441 of the second starting circuit 44 is, for example, a reed switch that is placed in an electromagnetic field generated by the current Ip flowing in the main electric circuit 9.

[0102] When the switch 441 of the second start-up circuit 44 is turned on, the second start-up circuit 44 supplies (a part of) the current Ip flowing through the main current path 9 to the squib 83 via the second circuit 4. The second start-up circuit 44 is electrically connected to the squib 83 without passing through the delay circuit 32 of the first circuit 3. Therefore, the second circuit 4 supplies power to the squib 83 at an earlier timing than the first circuit 3.

[0103] The second circuit 4, including the second starting circuit 44, supplies power to the squib 83 only when a large overcurrent flows through the main electric circuit 9, and does not supply power to the squib 83 when a small overcurrent flows through the main electric circuit. In other words, the threshold current value (second current threshold) of the current Ip flowing through the main electric circuit 9, which is necessary to supply power to the squib 83 via the second circuit 4, is greater than the threshold current value (first current threshold) of the current Ip flowing through the main electric circuit 9, which is necessary to supply power to the squib 83 via the first circuit 3 (first current threshold<second current threshold). In one specific example, the pull-in value of the switch 441 (reed switch) of the second starting circuit 44 is greater than the pull-in value of the switch 214 (reed switch) of the first starting circuit 21. In one embodiment, the distance from the main electrical circuit 9 to the switch 441 (reed switch) of the second starting circuit 44 is greater than the distance from the main electrical circuit 9 to the switch 214 (reed switch) of the first starting circuit 21 .

[0104] In the circuit breaking system 100 of this embodiment, similarly to the circuit breaking system 100 of embodiment 3 (see FIGS. 7 and 8 ), when an overcurrent with a small current value flows through the main electric circuit 9 for a relatively long period of time, the first circuit 3 can activate the squib 83. Furthermore, when an overcurrent with a large current value flows through the main electric circuit 9, the second circuit 4 can instantly activate the squib 83. Furthermore, when an overcurrent with a small current value that does not damage the relay 93, the load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor 323 of the delay circuit 32 of the first circuit 3 is not sufficiently charged and the second circuit 4 is not turned on, thereby preventing the activation of the squib 83.

[0105] The second circuit 4 may further include a switch circuit (see the fifth switch circuit 43 in the fourth embodiment, etc.) electrically connected between the second start circuit 44 (switch 441) and the squib 83.

[0106] In this embodiment, it is possible to omit the first switch circuit 31, the second switch circuit 33, and / or the third switch circuit 22. Furthermore, instead of a reed switch, a relay, a semiconductor relay, a transistor, a MOS-FET, or the like may be used as the switch 214 of the first start circuit 21 and / or the switch 441 of the second start circuit 44.

[0107] (6) Sixth Embodiment The interruption system 100 of this embodiment will be described with reference to Fig. 12 and Fig. 13. Fig. 12 is a block diagram of the interruption system 100 of this embodiment in a state before the main electric line 9 is broken. Fig. 13 shows an example of a circuit diagram of this embodiment.

[0108] As shown in Fig. 12, the ignition circuit 1 of this embodiment further includes a second circuit 4 in addition to the elements of the ignition circuit 1 of embodiment 2 (see Fig. 5). If the starter circuit 21 of the ignition circuit 1 of embodiment 2 is defined as the "first starter circuit 21," the second circuit 4 includes a second starter circuit 44 that is different from the first starter circuit 21. In other words, the ignition circuit 1 further includes the second starter circuit 44 that is electrically connected to the squib 83 without passing through the delay circuit 32.

[0109] 12, the second starting circuit 44 includes a coil 442. For convenience, hereinafter, the coil 211 of the first starting circuit 21 will also be referred to as the "first coil 211," and the coil 442 of the second starting circuit 44 will also be referred to as the "second coil 442."

[0110] The second coil 442 generates a voltage for power supplied to the squib 83 by electromagnetic induction in response to changes in the current Ip flowing through the main electric circuit 9 (for example, the intermediate electric circuit 90 in FIG. 12 ). The second coil 442 is wound around, for example, a core (yoke). The main electric circuit 9 (intermediate electric circuit 90) is disposed so as to pass through the core. The second coil 442, the core, and the main electric circuit 9 constitute a transformer. Power resulting from the voltage generated by the second coil 442 is supplied to the squib 83.

[0111] 13 , the second start-up circuit 44 further includes a diode (rectifier circuit) 443 and a resistor 444. A parallel circuit of the diode 443 and the resistor 444 is electrically connected between both ends of the second coil 442. The cathode of the diode 443 is connected to a first end of the second coil 442, and the anode of the diode 443 is connected to a second end of the second coil 442.

[0112] For example, the second coil 442 of the second starting circuit 44 is less sensitive to magnetic fields than the first coil 211 of the first starting circuit 21. In other words, the voltage generated by the second coil 442 of the second starting circuit 44 in response to changes in the current Ip flowing through the main electric circuit 9 is smaller than the voltage generated by the first coil 211 of the first starting circuit 21.

[0113] As shown in FIG. 13 , the second circuit 4 further includes a switch circuit 45 (hereinafter also referred to as the “sixth switch circuit 45”) electrically connected between the second starting circuit 44 (second coil 442) and the squib 83.

[0114] As shown in FIG. 13, the sixth switch circuit 45 includes a thyristor 451 , a diode 452 , a Zener diode 453 , a resistor 454 , and a capacitor 455 .

[0115] The anode of the thyristor 451 is electrically connected to the second starter circuit 44. The cathode of the thyristor 451 is electrically connected to the squib 83.

[0116] The cathodes of the diode 452 and the Zener diode 453 are electrically connected to each other. The anode of the diode 452 is electrically connected to the anode of the thyristor 451. The anode of the Zener diode 453 is electrically connected to the gate of the thyristor 451.

[0117] A parallel circuit of a resistor 454 and a capacitor 455 is electrically connected between the gate and cathode of the thyristor 451 .

[0118] In the sixth switch circuit 45, when a voltage equal to or greater than the threshold voltage is applied to the sixth switch circuit 45, a current flows to the gate of the thyristor 451, turning on the thyristor 451. This turns on the sixth switch circuit 45.

[0119] As described above, the second coil 442 of the second starting circuit 44 is less sensitive to magnetic fields than the first coil 211 of the first starting circuit 21. Therefore, for example, when an overcurrent with a small current value flows through the main electric circuit 9, the third switch circuit 22 is turned on but the sixth switch circuit 45 is not turned on. On the other hand, when an overcurrent with a large current value flows through the main electric circuit 9, the voltage generated by the second coil 442 immediately turns on the sixth switch circuit 45.

[0120] In short, in the circuit breaking system 100 of this embodiment, when a small overcurrent flows through the main electric circuit 9 for a short period of time, neither the first circuit 3 nor the second circuit 4 is turned on, and power is not supplied to the squib 83. On the other hand, when a small overcurrent flows through the main electric circuit 9 for a relatively long period of time, the second circuit 4 is not turned on, but the first circuit 3 is turned on, and power is supplied to the squib 83 by the voltage generated by the first coil 211 of the first starting circuit 21, activating the squib 83. Furthermore, when a large overcurrent flows instantaneously through the main electric circuit 9, the sixth switch circuit 45 is turned on by the voltage generated by the second coil 442 of the second starting circuit 44, and power is instantly supplied to the squib 83 by the voltage generated by the second coil 442.

[0121] In the circuit breaking system 100 of this embodiment, similarly to the circuit breaking system 100 of embodiment 3 (see FIGS. 7 and 8 ), when an overcurrent with a small current value flows through the main electric circuit 9 for a relatively long period of time, the first circuit 3 can activate the squib 83. Furthermore, when an overcurrent with a large current value flows through the main electric circuit 9, the second circuit 4 can instantly activate the squib 83. Furthermore, when an overcurrent with a small current value that does not damage the relay 93, the load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor 323 of the delay circuit 32 of the first circuit 3 is not sufficiently charged and the second circuit 4 is not turned on, thereby preventing the activation of the squib 83.

[0122] (7) Seventh Embodiment The interruption system 100 of this embodiment will be described with reference to Fig. 14 and Fig. 15. Fig. 14 is a block diagram of the interruption system 100 of this embodiment in a state before the main electric line 9 is broken. Fig. 15 shows an example of a circuit diagram of this embodiment.

[0123] The ignition circuit 1 of this embodiment includes a switch 445 electrically connected to the first coil 211 of the first starting circuit 21, instead of the second coil 442 of the second starting circuit 44 of the sixth embodiment. The switch 445 of the second starting circuit 44 is turned on when an overcurrent flows in the main electric circuit 9. The switch 445 of the second starting circuit 44 is, for example, a reed switch disposed in an electromagnetic field generated by the current Ip flowing through the main electric circuit 9.

[0124] When the switch 445 of the second start-up circuit 44 is turned on, the second start-up circuit 44 supplies (a portion of) the power generated by the first coil 211 to the squib 83 via the second circuit 4. The second start-up circuit 44 is electrically connected to the squib 83 without going through the delay circuit 32 of the first circuit 3. Therefore, the second circuit 4 supplies power to the squib 83 at an earlier timing than the first circuit 3.

[0125] The second circuit 4 including the second start circuit 44 supplies power to the squib 83 only when a large overcurrent flows through the main electric circuit 9, and does not supply power to the squib 83 when a small overcurrent flows through the main electric circuit 9. In other words, the threshold current value (second current threshold) of the current Ip flowing through the main electric circuit 9, which is necessary to turn on the switch 445 of the second start circuit 44 of the second circuit 4, is greater than the threshold current value (first current threshold) of the current Ip flowing through the main electric circuit 9, which is necessary to supply power to the squib 83 via the first circuit 3 (first current threshold<second current threshold).

[0126] In the circuit breaking system 100 of this embodiment, if an overcurrent with a small current value flows for a relatively long time through the main electric circuit 9, the first circuit 3 can activate the squib 83. Furthermore, if an overcurrent with a large current value flows through the main electric circuit 9, the second circuit 4 can instantly activate the squib 83. Furthermore, if an overcurrent with a small current value that does not damage the relay 93, the load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor 323 of the delay circuit 32 of the first circuit 3 is not sufficiently charged and the switch 445 of the second circuit 4 is not turned on, preventing the activation of the squib 83.

[0127] 15 , the second start-up circuit 44 may be electrically connected to the first start-up circuit 21 via the third switch circuit 22 and the power storage circuit 23. In the example of FIG. 15 , the second start-up circuit 44 further includes a capacitor 446 and a resistor 447. A first end of the capacitor 446 is electrically connected to a first end of the capacitor 231 of the power storage circuit 23 via a switch 445. A second end of the capacitor 446 is electrically connected to a second end of the capacitor 231 of the power storage circuit 23. The resistor 447 is electrically connected across the capacitor 446.

[0128] Furthermore, the second circuit 4 of this embodiment, like the second circuit 4 of embodiment 6 (see FIG. 13 ), further includes a sixth switch circuit 45 electrically connected between the second start-up circuit 44 (switch 445) and the squib 83.

[0129] In this embodiment, it is possible to omit the first switch circuit 31, and / or the second switch circuit 33, and / or the third switch circuit 22. Furthermore, instead of a reed switch, a relay, a semiconductor relay, a transistor, a MOS-FET, or the like may be used as the switch 445 of the second start-up circuit 44.

[0130] (8) Eighth Embodiment The interruption system 100 of this embodiment will be described with reference to Figs. 16 to 18. Fig. 16 is a block diagram of the interruption system 100 of this embodiment in a state before the main electric circuit 9 is broken. Fig. 17 shows an example of a circuit diagram of this embodiment. Fig. 18 shows the characteristics of the output voltage Vs1 of the first magnetic sensor 332 and the characteristics of the output voltage Vs2 of the second magnetic sensor 421 provided in the ignition circuit 1.

[0131] The ignition circuit 1 of this embodiment is different from the ignition circuit 1 of embodiment 3 (see FIGS. 7 and 8 ) in that the second switch circuit 33 includes a magnetic sensor 332 (hereinafter also referred to as a “first magnetic sensor 332”) and a switch instead of the reed switch 331. The switch here is a transistor 333.

[0132] 17 , the transistor 333 is connected in series with the capacitor 323 included in the delay circuit 32. The base of the transistor 333 is electrically connected to the output terminal of the first magnetic sensor 332. The collector of the transistor 333 is electrically connected to a first terminal of the capacitor 231 of the storage circuit 23. The emitter of the transistor 333 is electrically connected to a first terminal of the resistor 321 of the delay circuit 32. A series circuit of the transistor 333 and the resistor 321 is connected between the base and collector of the transistor 316 of the first switch circuit 31.

[0133] The first magnetic sensor 332 is disposed in an electromagnetic field generated by the current Ip flowing through the main electric circuit 9. The first magnetic sensor 332 is electrically connected to the power supply circuit 41 and operates using operating power supplied from the power supply circuit 41. For convenience, the magnetic sensor 421 included in the second circuit 4 will also be referred to as the "second magnetic sensor 421" below. The first magnetic sensor 332 and the second magnetic sensor 421 include, for example, a Hall element.

[0134] 18 , the first magnetic sensor 332 outputs a low-level voltage VL when the strength of the magnetic field applied to the first magnetic sensor 332 is equal to or greater than a first intensity threshold Hth1, and outputs a high-level voltage VH when the strength of the magnetic field applied to the first magnetic sensor 332 is less than the first intensity threshold Hth1. The second magnetic sensor 421 outputs a low-level voltage VL when the strength of the magnetic field applied to the second magnetic sensor 421 is equal to or greater than a second intensity threshold Hth2, and outputs a high-level voltage VH when the strength of the magnetic field applied to the second magnetic sensor 421 is less than the second intensity threshold Hth2. The second intensity threshold Hth2 is greater than the first intensity threshold Hth1 (Hth2>Hth1).

[0135] In the first circuit 3, when the strength of the magnetic field (first magnetic field) applied to the first magnetic sensor 332 is equal to or greater than the first strength threshold Hth1, the first magnetic sensor 332 outputs a low-level voltage, turning off the transistor 333 (switch). Then, in the first circuit 3, after the delay time (the time required to charge the capacitor 323) set by the delay circuit 32 has elapsed, the first switch circuit 31 is turned on to supply power to the squib 83. Because the first circuit 3 includes the delay circuit 32, the time (first time) from when an overcurrent flows in the main current circuit 9 to when power is supplied to the squib 83 via the first circuit 3 is relatively long.

[0136] The second circuit 4 supplies power to the squib 83 when the strength of the magnetic field (second magnetic field) applied to the second magnetic sensor 421 is equal to or greater than a second strength threshold Hth2. The second strength threshold Hth2 is greater than the first strength threshold Hth1. The second circuit 4 does not include a delay circuit. Therefore, the time (second time) from when an overcurrent flows in the main current circuit 9 to when power is supplied to the squib 83 via the second circuit 4 is shorter than the first time.

[0137] In the circuit breaking system 100 of this embodiment, similarly to the circuit breaking system 100 of embodiment 3 (see FIGS. 7 and 8 ), when an overcurrent with a small current value flows through the main electric circuit 9 for a relatively long period of time, the squib 83 can be activated by the first circuit 3. Furthermore, when an overcurrent with a large current value flows through the main electric circuit 9, the squib 83 can be instantly activated by the second circuit 4. Furthermore, when an overcurrent with a small current value that does not damage the relay 93, the load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor 323 of the delay circuit 32 of the first circuit 3 is not sufficiently charged and the second circuit 4 is not turned on, thereby preventing the activation of the squib 83.

[0138] Furthermore, the reed switch 331 used as the switch circuit (second switch circuit 33) in the interruption system 100 of embodiment 3 (see FIGS. 7 and 8) or the interruption system 100 of embodiment 7 (see FIGS. 14 and 15) generally has a large difference between its pull-in and drop-out values ​​(pull-in > drop-out). As a result, there is a problem that variations in operation are likely to occur. In contrast, the interruption system 100 of this embodiment is configured using a magnetic sensor (Hall element), thereby making it possible to improve the accuracy of operation.

[0139] (9) Embodiment 9 An interruption system 100 of this embodiment will be described with reference to Fig. 19 and Fig. 20. Fig. 19 shows an example of a circuit diagram of this embodiment. Fig. 20 shows the characteristics of the output voltage Vs10 of the magnetic sensor 520 provided in the ignition circuit 1.

[0140] The ignition circuit 1 of this embodiment includes a magnetic sensor 520. The magnetic sensor 520 includes, for example, a Hall element. The magnetic sensor 520 is disposed in an electromagnetic field generated by the current Ip flowing through the main current circuit 9. As shown in FIG. 20 , the output (output voltage Vs10) of the magnetic sensor 520 of this embodiment changes linearly depending on the strength of the magnetic field applied to (detected by) the magnetic sensor 520. In the example of FIG. 20 , the output voltage Vs10 of the magnetic sensor 520 is centered at a strength V0 / 2 when the detected magnetic field is 0 mT, and changes linearly between V1 and V0-V1 depending on the detected magnetic field.

[0141] The ignition circuit 1 of this embodiment further includes a power supply circuit 51. In the ignition circuit 1, the first circuit 3 includes a first determination circuit 34, a delay circuit 32, a switch circuit (hereinafter also referred to as the “seventh switch circuit”) 35, and the first switch circuit 31. The second circuit 4 includes a second determination circuit 46, a switch circuit (hereinafter also referred to as the “eighth switch circuit”) 47, and a fifth switch circuit 43.

[0142] The power supply circuit 51 includes a Zener diode 511 and a resistor 512 .

[0143] The series circuit of the Zener diode 511 and the resistor 512 is electrically connected across the capacitor 231 of the storage circuit 23. A first end of the resistor 512 is electrically connected to the first end of the capacitor 231 of the storage circuit 23, a second end of the resistor 512 is electrically connected to the cathode of the Zener diode 511, and an anode of the Zener diode 511 is electrically connected to the second end of the capacitor 231 of the storage circuit 23.

[0144] The power supply circuit 51 generates operating power for the magnetic sensor 520 using the power stored in the capacitor 231 of the power storage circuit 23 .

[0145] The first determination circuit 34 of the first circuit 3 compares the output voltage Vs10 of the magnetic sensor 520 with a first threshold voltage Vth1. As shown in FIG. 19 , the first determination circuit 34 includes a comparator 341, a setting unit (hereinafter also referred to as the “first setting unit”) 342 that outputs the first threshold voltage Vth1, and voltage-dividing resistors 343 and 344. The non-inverting input terminal of the comparator 341 is electrically connected to the output terminal of the magnetic sensor 520. The inverting input terminal of the comparator 341 is electrically connected to the first setting unit 342. The comparator 341 of the first determination circuit 34 outputs a high-level voltage when the output voltage Vs10 of the magnetic sensor 520 is equal to or greater than the first threshold voltage Vth1.

[0146] The delay circuit 32 is electrically connected to the output terminal of the comparator 341 of the first determination circuit 34. The delay circuit 32 includes, for example, a resistor and a capacitor. A first end of the resistor is electrically connected to the output terminal of the comparator 341, a second end of the resistor is electrically connected to a first end of the capacitor, and a second end of the capacitor is electrically connected to a second end of the capacitor 231 of the storage circuit 23. The output end of the delay circuit 32 is electrically connected to a connection point of the voltage-dividing resistors 343 and 344. The voltage-dividing resistors 343 and 344 are electrically connected across the capacitor 231 of the storage circuit 23.

[0147] The seventh switch circuit 35 includes a resistor 351 and a MOSFET 352 .

[0148] A first end of the resistor 351 is electrically connected to a first end of the capacitor 231 of the storage circuit 23. The MOSFET 352 is a normally-off (normally open) switch. The gate of the MOSFET 352 is electrically connected to the connection point between the resistors 343 and 344. The drain of the MOSFET 352 is electrically connected to a second end of the resistor 351. The source of the MOSFET 352 is electrically connected to the second end of the capacitor 231 of the storage circuit 23.

[0149] In the seventh switch circuit 35, when the output voltage of the comparator 341 of the first determination circuit 34 is at a low level, the MOSFET 352 is off. When the output voltage of the comparator 341 changes from a low level to a high level, the MOSFET 352 is turned on after the delay time set by the delay circuit 32 has elapsed.

[0150] The base of the transistor 316 of the first switch circuit 31 is electrically connected to the connection point between the second end of the resistor 351 of the seventh switch circuit 35 and the drain of the MOSFET 352 .

[0151] In the first switch circuit 31, when the output voltage of the comparator 341 of the first determination circuit 34 is at a low level, the transistor 316 and the thyristor 311 are maintained off, and the first switch circuit 31 is maintained off. When the strength of the magnetic field applied to the magnetic sensor 520 increases and the output voltage of the comparator 341 switches to a high level, the MOSFET 352 of the seventh switch circuit 35 is turned on after a delay time has elapsed, and the transistor 316 and the thyristor 311 are turned on. This turns on the first switch circuit 31.

[0152] That is, in the first circuit 3, after the delay time set by the delay circuit 32 has elapsed, the first switch circuit 31 is turned on to supply power to the squib 83. In short, when the strength of the magnetic field detected by the magnetic sensor 520 is equal to or greater than the first strength threshold (the strength of the magnetic field corresponding to the first threshold voltage Vth1), the first circuit 3 supplies power to the squib 83 after the delay time set by the delay circuit 32 has elapsed.

[0153] The second determination circuit 46 of the second circuit 4 compares the output voltage Vs10 of the magnetic sensor 520 with a second threshold voltage Vth2. As shown in FIG. 19 , the second determination circuit 46 includes a comparator 461, a setting unit (hereinafter also referred to as the “second setting unit”) 462 that outputs the second threshold voltage Vth2, and voltage-dividing resistors 463 and 464. The non-inverting input terminal of the comparator 461 is electrically connected to the output terminal of the magnetic sensor 520. The inverting input terminal of the comparator 461 is electrically connected to the second setting unit 462. The voltage-dividing resistors 463 and 464 are electrically connected across the capacitor 231 of the power storage circuit 23.

[0154] The second threshold voltage Vth2 is greater than the first threshold voltage Vth1. When the output voltage of the magnetic sensor 520 is equal to or greater than the second threshold voltage Vth2, the second determination circuit 46 outputs a high-level voltage.

[0155] The eighth switch circuit 47 includes a resistor 471 and a MOSFET 472 .

[0156] A first end of the resistor 471 is electrically connected to a first end of the capacitor 231 of the power storage circuit 23. The MOSFET 472 is a normally-off (normally open) switch. The gate of the MOSFET 472 is electrically connected to the connection point between the resistor 463 and the resistor 464. The drain of the MOSFET 472 is electrically connected to a second end of the resistor 471. The source of the MOSFET 472 is electrically connected to the second end of the capacitor 231 of the power storage circuit 23.

[0157] In the eighth switch circuit 47, when the output voltage of the comparator 461 of the second determination circuit 46 is at a low level, the MOSFET 472 is turned off. When the output voltage of the comparator 461 changes from a low level to a high level, the MOSFET 472 is immediately turned on.

[0158] The base of the transistor 436 of the fifth switch circuit 43 is electrically connected to the connection point between the second end of the resistor 471 and the drain of the MOSFET 472 of the eighth switch circuit 47 .

[0159] In the fifth switch circuit 43, when the output voltage of the comparator 461 of the second determination circuit 46 is at a low level, the transistor 436 and the thyristor 431 are maintained off, and the fifth switch circuit 43 is maintained off. When the strength of the magnetic field applied to the magnetic sensor 520 increases and the output voltage of the comparator 461 of the second determination circuit 46 switches to a high level, the MOSFET 472 of the eighth switch circuit 47 is immediately turned on, and the transistor 436 and the thyristor 431 are turned on. This turns on the fifth switch circuit 43.

[0160] That is, in the second circuit 4, when a large current flows through the main current circuit 9 and the output voltage Vs10 from the magnetic sensor 520 becomes equal to or greater than the second threshold voltage Vth2, the fifth switch circuit 43 is immediately turned on to supply power to the squib 83. In short, the second circuit 4 supplies power to the squib 83 at an earlier timing than the first circuit 3 when the strength of the magnetic field detected by the magnetic sensor 520 is equal to or greater than a second strength threshold (magnetic field strength corresponding to the second threshold voltage Vth2) that is greater than the first strength threshold.

[0161] In the circuit breaking system 100 of this embodiment, too, if a small overcurrent flows for a relatively long time in the main electric circuit 9, the first circuit 3 can activate the squib 83. Moreover, if a large overcurrent flows in the main electric circuit 9, the second circuit 4 can instantly activate the squib 83. Furthermore, if a small overcurrent that does not damage the relay 93, load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor 323 of the delay circuit 32 of the first circuit 3 is not sufficiently charged and the second circuit 4 is not turned on, preventing the activation of the squib 83.

[0162] Furthermore, the blocking system 100 of this embodiment can also improve the accuracy of its operation by using the magnetic sensor 520 (Hall element).

[0163] (10) Tenth Embodiment An interruption system 100 of this embodiment will be described with reference to Fig. 21. Fig. 21 shows an example of a circuit diagram of this embodiment.

[0164] The ignition circuit 1 of this embodiment includes, in addition to the first switch circuit 31 and the delay circuit 32, a power supply circuit 51, a magnetic sensor 520, a first determination circuit 34, a second determination circuit 46, and a seventh switch circuit 35.

[0165] The magnetic sensor 520 is placed in an electromagnetic field generated by the current Ip flowing through the main current circuit 9. As with the magnetic sensor 520 of the ninth embodiment, the output (output voltage Vs10) of the magnetic sensor 520 of this embodiment changes linearly in accordance with the strength of the magnetic field applied to (detected by) the magnetic sensor 520 (see FIG. 20 ).

[0166] The first determination circuit 34 is electrically connected to the first switch circuit 31 via the delay circuit 32. The first determination circuit 34 compares the output voltage Vs10 of the magnetic sensor 520 with a first threshold voltage Vth1. If the output voltage Vs10 of the magnetic sensor 520 is equal to or greater than the first threshold voltage Vth1, the first determination circuit 34 outputs a High-level voltage. As a result, after the delay time set by the delay circuit 32 has elapsed, the first switch circuit 31 is turned on and power is supplied to the squib 83.

[0167] The second determination circuit 46 is electrically connected to the first switch circuit 31 without a delay circuit. The second determination circuit 46 compares the output voltage Vs10 of the magnetic sensor 520 with a second threshold voltage Vth2. The second threshold voltage Vth2 is greater than the first threshold voltage Vth1. The second determination circuit 46 outputs a high-level voltage when the output voltage Vs10 of the magnetic sensor 520 is equal to or greater than the second threshold voltage Vth2. As a result, in the ignition circuit 1, when a large current flows through the main current path 9 and the output voltage Vs10 from the magnetic sensor 520 becomes equal to or greater than the second threshold voltage Vth2, the first switch circuit 31 is immediately turned on, and power is supplied to the squib 83.

[0168] In the circuit breaking system 100 of this embodiment, too, if a small overcurrent flows through the main electric circuit 9 for a relatively long period of time, the first determination circuit 34 can activate the squib 83. Moreover, if a large overcurrent flows through the main electric circuit 9, the second determination circuit 46 can instantly activate the squib 83. Furthermore, if a small overcurrent that does not damage the relay 93, load 92, etc., flows instantaneously through the main electric circuit 9, the capacitor of the delay circuit 32 will not be sufficiently charged and the second determination circuit 46 will not output a high-level voltage, preventing the squib 83 from being activated.

[0169] In this way, the blocking system 100 of this embodiment can also obtain the same effects as those of the ninth embodiment and the like.

[0170] Furthermore, the blocking system 100 of this embodiment can also improve the accuracy of its operation by using the magnetic sensor 520 (Hall element).

[0171] Furthermore, in the shutdown system 100 of this embodiment, the fifth switch circuit 43 (and the eighth switch circuit 47) in the shutdown system 100 of the ninth embodiment can be omitted, and therefore the circuit size can be reduced.

[0172] (11) Embodiment 11 An interruption system 100 of this embodiment will be described with reference to Fig. 22 to Fig. 24. Fig. 22 shows an example of a circuit diagram of this embodiment. Fig. 23 shows the arrangement of a first magnetic sensor 521 and a second magnetic sensor 522 provided in the ignition circuit 1. Fig. 24 shows the characteristics of the output voltage Vs11 of the first magnetic sensor 521 and the output voltage Vs12 of the second magnetic sensor 522.

[0173] The ignition circuit 1 of this embodiment includes a first magnetic sensor 521, a second magnetic sensor 522, and a differential amplifier circuit 53 instead of the magnetic sensor 520 in the ignition circuit 1 of embodiment 9 (see FIG. 19).

[0174] Each of the first magnetic sensor 521 and the second magnetic sensor 522 includes, for example, a Hall element. As shown in FIG. 23 , the first magnetic sensor 521 and the second magnetic sensor 522 are mounted on a substrate 529 having a through-hole 528 through which the main electric circuit 9 passes. That is, the first magnetic sensor 521 and the second magnetic sensor 522 are disposed in an electromagnetic field generated by the current Ip flowing through the main electric circuit 9. The first magnetic sensor 521 and the second magnetic sensor 522 are disposed near a first portion 901 of the main electric circuit 9. However, as shown in FIG. 23 , the first magnetic sensor 521 and the second magnetic sensor 522 are disposed at the same distance from the first portion 901 of the main electric circuit 9 and on opposite sides of the first portion 901 of the main electric circuit 9 (with the first portion 901 sandwiched between the first magnetic sensor 521 and the second magnetic sensor 522). 24, the output voltage Vs12 output by the second magnetic sensor 522 in response to the magnetic field generated by the current Ip flowing through the first portion 901 of the main electric circuit 9 is the opposite of the output voltage Vs11 output by the first magnetic sensor 521, with respect to the reference voltage V0. The horizontal axes in FIG. 24 represent the magnetic field applied to the first magnetic sensor 521 and the magnetic field applied to the second magnetic sensor 522. As shown in FIG. 24, for example, when the magnitude of the magnetic field caused by the current Ip flowing through the first portion 901 of the main electric circuit 9 is HR, the output voltage Vs11 of the first magnetic sensor 521 is V0+VA, and the output voltage Vs12 of the second magnetic sensor 522 is V0-VA.

[0175] The differential amplifier circuit 53 includes an operational amplifier 531 and resistors 532 , 533 , 534 , and 535 .

[0176] The inverting input terminal of the operational amplifier 531 is electrically connected to the output terminal of the first magnetic sensor 521 via a resistor 532. The output terminal of the operational amplifier 531 is electrically connected to the inverting input terminal of the operational amplifier via a resistor 533. The non-inverting input terminal of the operational amplifier 531 is electrically connected to the output terminal of the second magnetic sensor 522 via a resistor 534. The non-inverting input terminal of the operational amplifier 531 is electrically connected to the second terminal of the capacitor 231 of the power storage circuit 23 via a resistor 535. The output terminal of the operational amplifier 531 is electrically connected to the non-inverting input terminal of the comparator 341 of the first determination circuit 34 and the non-inverting input terminal of the comparator 461 of the second determination circuit 46.

[0177] The differential amplifier circuit 53 outputs a voltage corresponding to the difference (Vs11-Vs12) between the output voltage Vs11 of the first magnetic sensor 521 and the output voltage Vs12 of the second magnetic sensor 522. For example, if the output voltage Vs11 of the first magnetic sensor 521 is V0+VA and the output voltage Vs12 of the second magnetic sensor 522 is V0-VA, the output voltage of the differential amplifier circuit 53 is 2VA.

[0178] 23 , a magnetic field (external magnetic field HA) other than the magnetic field H1 generated by the current Ip flowing through the first portion 901 of the main electric circuit 9 may also act on the first magnetic sensor 521 and the second magnetic sensor 522. Examples of the external magnetic field HA include a magnetic field generated by the current Ip flowing through the second portion 902 of the main electric circuit 9 that is distant from the first magnetic sensor 521 and the second magnetic sensor 522, and a magnetic field generated by an external device mounted on the vehicle in which the interruption system 100 is mounted. For example, in the interruption system 100 of the ninth embodiment, when the magnetic sensor 520 detects the external magnetic field HA, the output voltage Vs10 of the magnetic sensor 520 increases, and this may cause the input voltage to the first determination circuit 34 (or the second determination circuit 46) to exceed the first threshold voltage Vth1 (or the second threshold voltage Vth2).

[0179] In contrast, in the interruption system 100 of the present embodiment, the first magnetic sensor 521 and the second magnetic sensor 522 are disposed at positions opposite to each other with respect to the main electric circuit 9. Therefore, as shown in FIG. 23 , the external magnetic field HA generated by the current Ip flowing through the second portion 902 acts in opposite directions on the first magnetic sensor 521 and the second magnetic sensor 522. Therefore, the influence of the external magnetic field HA can be canceled out by using the differential amplifier circuit 53 to obtain the difference between the output voltage Vs11 of the first magnetic sensor 521 and the output voltage Vs12 of the second magnetic sensor 522. This makes it less likely that the external magnetic field HA will cause the input voltage to the first determination circuit 34 (or the second determination circuit 46) to exceed the first threshold voltage Vth1 (or the second threshold voltage Vth2).

[0180] (12) Twelfth Embodiment An interruption system 100 of this embodiment will be described with reference to Fig. 25. Fig. 25 shows an example of a circuit diagram of this embodiment.

[0181] The ignition circuit 1 of this embodiment includes a first magnetic sensor 521, a second magnetic sensor 522, and a differential amplifier circuit 53 instead of the magnetic sensor 520 in the ignition circuit 1 of embodiment 10 (see FIG. 21).

[0182] Note that the first magnetic sensor 521, the second magnetic sensor 522, and the differential amplifier circuit 53 of this embodiment are substantially identical to the first magnetic sensor 521, the second magnetic sensor 522, and the differential amplifier circuit 53 of embodiment 11, respectively, and therefore detailed explanations will be omitted.

[0183] The ignition circuit 1 and the interruption system 100 of this embodiment can also reduce the influence of the external magnetic field HA, similar to the eleventh embodiment.

[0184] (13) Thirteenth Embodiment The shutdown system 100 of this embodiment will be described with reference to Fig. 26 and Fig. 27. Fig. 26 is a block diagram of the shutdown system 100 of this embodiment.

[0185] The ignition circuit 1 of this embodiment is the same as the ignition circuit 1 of embodiment 9 (see FIGS. 19 and 20 ), except that it includes a processor 6 (microcomputer) and a switch circuit (first switch circuit) 31 instead of the first circuit 3 and the second circuit 4. The processor 6 is connected to the first switch circuit 31.

[0186] The magnetic sensor 520 is placed in an electromagnetic field generated by the current Ip flowing through the main current circuit 9. Similarly to the magnetic sensor 520 of the ninth embodiment, the output (output voltage Vs10) of the magnetic sensor 520 of this embodiment changes linearly in accordance with the strength of the magnetic field H applied to (detected by) the magnetic sensor 520 (see FIG. 20 ).

[0187] The processor 6 includes a delay circuit 32. The processor 6 delays the supply of power to the squib 83 via the first switch circuit 31 in accordance with the strength of the magnetic field detected by the magnetic sensor 520. The processor 6 shortens the delay time as the strength of the magnetic field H detected by the magnetic sensor 520 increases. The memory unit of the processor 6 stores, for example in the form of a correspondence table, a correspondence relationship between the strength of the magnetic field H detected by the magnetic sensor 520 (i.e., the magnitude of the current Ip flowing in the main electric circuit 9, which is the source of the magnetic field H detected by the magnetic sensor 520) and the delay time.

[0188] 27 illustrates an example of the operation of the processor 6. Specifically, the processor 6 determines whether the magnetic sensor 520 detects a magnetic field H having a certain strength (threshold Th1: for example, the strength of the magnetic field corresponding to a 1.8 kA overcurrent flowing in the main electric circuit) or greater (ST1). If the magnetic sensor 520 detects a magnetic field H having a strength equal to or greater than the threshold Th1 (ST1: Yes), the processor 6 sets a delay time according to the magnitude of the overcurrent flowing in the main electric circuit 9 based on a correspondence table stored in the memory unit (ST2). Furthermore, if the magnetic sensor 520 detects a magnetic field H having a strength equal to or greater than the threshold Th1 (ST1: Yes), the processor 6 starts counting time (ST3). During the time count, the processor 6 periodically determines whether the magnetic field H detected by the magnetic sensor 520 is equal to or greater than the threshold Th1 (ST4). If the magnetic field H detected by the magnetic sensor 520 remains equal to or greater than the threshold value Th1 (ST4: Yes) and the set delay time has elapsed (ST5: Yes), the processor 6 turns on the first switch circuit 31 to supply power to the squib 83 (ST6). Note that if the magnetic field H detected by the magnetic sensor 520 falls below the threshold value Th1 during the time count (before the set delay time has elapsed) (ST4: No), the processor 6 ends the process without turning on the first switch circuit 31.

[0189] In short, in the circuit breaking system 100 of this embodiment, for example, when a small overcurrent (e.g., 2 kA) flows through the main electric circuit 9, the processor 6 turns on the first switch circuit 31 after a corresponding delay time (e.g., 1 s) has elapsed, thereby activating the squib 83. Also, when a large overcurrent (e.g., 10 kA) flows through the main electric circuit 9, the processor 6 turns on the first switch circuit 31 after a corresponding delay time (e.g., 0.1 ms) has elapsed, thereby immediately activating the squib 83. Also, when a small overcurrent (e.g., 2 kA) that does not damage the relay 93, the load 92, etc., flows through the main electric circuit 9 momentarily (e.g., 0.1 s), the processor 6 keeps the first switch circuit 31 off, and does not activate the squib 83.

[0190] In this way, the blocking system 100 of this embodiment can also obtain the same effects as those of the ninth embodiment and the like.

[0191] Note that "the processor 6 includes the delay circuit 32" does not necessarily mean that the processor 6 has a circuit configuration dedicated to the delay circuit 32, but rather that the function of the delay circuit 32 may be realized by software. Furthermore, the first switch circuit 31 of the present embodiment is not limited to the circuit configuration shown in FIG. 5 and the like, but may be any switch element (for example, a configuration including only a semiconductor switch). Furthermore, the interruption system 100 may include the first magnetic sensor 521, the second magnetic sensor 522, and the differential amplifier circuit 53 of the tenth embodiment, instead of the magnetic sensor 520.

[0192] (14) Modification In the interruption system 100 of the third embodiment (see FIG. 7 ), the ignition circuit 1 does not have to include the first circuit 3. It is possible to provide an ignition circuit 1 that can immediately activate the squib 83 when a large overcurrent flows in the main electric circuit 9, and that can prevent the squib 83 from activating when a small overcurrent flows.

[0193] Each of the first switch circuit 31, the third switch circuit 22, the fifth switch circuit 43, and the sixth switch circuit 45 may be, for example, SIDAC (registered trademark). Also, the diodes 222, 312, and 452 may be omitted as appropriate.

[0194] (15) Aspects As is clear from the above-described embodiments and modifications, the present specification discloses the following aspects.

[0195] The ignition circuit (1) of the first embodiment is electrically connected to a circuit breaker (8). The circuit breaker (8) includes a first terminal (81), a second terminal (82), a squib (83), and a projectile (84). The second terminal (82) is electrically connected to the first terminal (81). The squib (83) is electrically connected to the ignition circuit (1). The squib (83) includes a gunpowder (834) that is ignited by the ignition circuit (1). The projectile (84) obtains thrust through combustion of the gunpowder (834) and interrupts the electrical connection between the first terminal (81) and the second terminal (82). The ignition circuit (1) includes a first switch circuit (31) and a delay circuit (32). The first switch circuit (31) is electrically connected to the squib (83). The first switch circuit (31) supplies power to the squib (83) when the input voltage is equal to or greater than a threshold. The delay circuit (32) is electrically connected to the squib (83) via the first switch circuit (31). The delay circuit (32) delays the supply of power to the squib (83) via the first switch circuit (31).

[0196] According to this embodiment, it is possible to prevent the squib (83) from operating in the event of a momentary overcurrent.

[0197] In the ignition circuit (1) of the second embodiment, the delay circuit (32) in the first embodiment includes a capacitor (323).

[0198] According to this embodiment, it is possible to prevent the squib (83) from operating in the event of a momentary overcurrent.

[0199] The ignition circuit (1) of the third aspect is the second aspect, and further includes a second switch circuit (33). The second switch circuit (33) supplies power to the squib (83) when a magnetic field of a certain strength or greater is applied.

[0200] According to this embodiment, it is possible to prevent the squib (83) from operating when a small overcurrent flows instantaneously.

[0201] In the ignition circuit (1) of the fourth aspect, in the third aspect, the second switch circuit (33) is electrically connected to the first switch circuit (31) via a delay circuit (32). The delay circuit (32) delays the supply of power from the second switch circuit (33) to the first switch circuit (31), thereby delaying the supply of power to the squib (83) via the first switch circuit (31).

[0202] According to this embodiment, it is possible to prevent the squib (83) from operating when a small overcurrent flows instantaneously.

[0203] In the ignition circuit (1) of the fifth aspect, the second switch circuit (33) of the third or fourth aspect includes a reed switch (331). The reed switch (331) is disposed in an electromagnetic field generated by a current flowing through a main electric circuit (9) electrically connected to a first terminal (81) of the circuit breaker (8).

[0204] According to this embodiment, even if an overcurrent flows in the main current circuit (9), if the overcurrent is only momentary, activation of the squib (83) can be prevented.

[0205] The ignition circuit (1) of a sixth aspect is any one of the first to fifth aspects, and includes a first circuit (3) including a first switch circuit (31) and a delay circuit (32), and a second circuit (4) electrically connected in parallel with the first circuit (3). When a predetermined condition is satisfied, the second circuit (4) supplies power to the squib (83) at an earlier timing than the first circuit (3).

[0206] According to this aspect, when a predetermined condition is met, the squib (83) can be immediately activated by the second circuit (4).

[0207] In the ignition circuit (1) of the seventh aspect, in the sixth aspect, the second circuit (4) includes a magnetic sensor (421). The second circuit (4) supplies power to the squib (83) when the strength of the magnetic field applied to the magnetic sensor (421) is equal to or greater than a certain strength.

[0208] According to this aspect, the second circuit (4) can be realized by the magnetic sensor (421).

[0209] In the ignition circuit (1) of the eighth aspect, in the seventh aspect, the magnetic sensor (421) includes a Hall element, a GMR element, an AMR element, or a reed switch.

[0210] According to this aspect, the second circuit (4) can be realized by the magnetic sensor (421).

[0211] In a ninth aspect of the ignition circuit (1), in the sixth aspect, the first circuit (3) includes a first magnetic sensor (332). The second circuit (4) includes a second magnetic sensor (421). When the intensity of the first magnetic field applied to the first magnetic sensor (332) is equal to or greater than a first intensity threshold, the first circuit (3) supplies power to the squib (83) after a delay time set by the delay circuit (32) has elapsed. When the intensity of the second magnetic field applied to the second magnetic sensor (421) is equal to or greater than a second intensity threshold that is greater than the first intensity threshold, the second circuit (4) supplies power to the squib (83) earlier than the first circuit (3).

[0212] According to this aspect, when a small overcurrent flows for a relatively long time, the squib (83) can be activated by the first circuit (3), and when a large overcurrent flows, the squib (83) can be immediately activated by the second circuit (4). Furthermore, by using magnetic sensors (first magnetic sensor 332, second magnetic sensor 421), the accuracy of operation can be improved.

[0213] The ignition circuit (1) of a tenth aspect is the sixth aspect, further comprising a magnetic sensor (520). When the strength of the magnetic field applied to the magnetic sensor (520) is equal to or greater than a first intensity threshold, the first circuit (3) supplies power to the squib (83) after a delay time set by the delay circuit (32) has elapsed. When the strength of the magnetic field applied to the magnetic sensor (520) is equal to or greater than a second intensity threshold that is greater than the first intensity threshold, the second circuit (4) supplies power to the squib (83) at an earlier timing than the first circuit (3).

[0214] According to this aspect, when a small overcurrent flows for a relatively long time, the squib (83) can be activated by the first circuit (3), and when a large overcurrent flows, the squib (83) can be immediately activated by the second circuit (4). In addition, by using a magnetic sensor (520), the accuracy of the operation can be improved.

[0215] The ignition circuit (1) of an eleventh aspect is any one of the first to third aspects, further comprising a magnetic sensor (520), a first determination circuit (34), and a second determination circuit (46). The first determination circuit (34) is electrically connected to the first switch circuit (31) via a delay circuit (32). The first determination circuit (34) compares the intensity of the magnetic field applied to the magnetic sensor (520) with a first intensity threshold. The second determination circuit (46) is electrically connected to the first switch circuit (31) without the delay circuit (32). The second determination circuit (46) compares the intensity of the magnetic field applied to the magnetic sensor (520) with a second intensity threshold that is greater than the first intensity threshold. When the strength of the magnetic field applied to the magnetic sensor (520) is equal to or greater than a first strength threshold, the first determination circuit (34) causes the first switch circuit (31) to supply power to the squib (83) after a delay time set by the delay circuit (32) has elapsed. When the strength of the magnetic field applied to the magnetic sensor (520) is equal to or greater than a second strength threshold, the second determination circuit (46) causes the first switch circuit (31) to supply power to the squib (83).

[0216] According to this aspect, when a small overcurrent flows for a relatively long time, the squib (83) can be activated by the first determination circuit (34), and when a large overcurrent flows, the squib (83) can be immediately activated by the second determination circuit (46). In addition, the use of a magnetic sensor (520) can improve the accuracy of the operation.

[0217] The ignition circuit (1) of a twelfth aspect is the same as that of the first aspect, but further includes a processor (6) and a magnetic sensor (520). The processor (6) includes a delay circuit (32). The processor (6) is connected to a first switch circuit (31). The processor (6) delays the supply of power to the squib (83) via the first switch circuit (31) by a delay time that corresponds to the strength of the magnetic field applied to the magnetic sensor (520).

[0218] According to this aspect, when an overcurrent with a small current value flows for a relatively long time, the squib (83) can be activated after a corresponding delay time has elapsed, and when an overcurrent with a large current value flows, the squib (83) can be activated immediately.

[0219] The ignition circuit (1) of a thirteenth aspect is the same as any one of the first to twelfth aspects, and further includes a starting circuit (21). The starting circuit (21) outputs power to be supplied to the squib (83) using the energy of a current flowing in a main current path (9) electrically connected to a first terminal (81) of the circuit breaker (8). The delay circuit (32) delays the supply of power from the starting circuit (21) to the first switch circuit (31), thereby delaying the supply of power to the squib (83) via the first switch circuit (31).

[0220] According to this embodiment, it is possible to prevent the squib (83) from operating in the event of a momentary overcurrent.

[0221] In the ignition circuit (1) of the fourteenth aspect, the starting circuit (21) in the thirteenth aspect includes a coil (211). The coil (211) generates a voltage for supplying power to the squib (83) by electromagnetic induction in response to changes in the current flowing through the main current path (9).

[0222] According to this embodiment, it is possible to generate power supplied to the squib (83) by the coil (211) using the current flowing through the main current path (9).

[0223] In the ignition circuit (1) of the fifteenth aspect, in the thirteenth aspect, the starting circuit (21) includes a switch (214) connected between the main current path (9) and the delay circuit (32).

[0224] According to this embodiment, the power of the current flowing through the main current path (9) can be used as the power supplied to the squib (83).

[0225] In the ignition circuit (1) of the 16th aspect, in any one of the 13th to 15th aspects, the starting circuit (21) is the first starting circuit (21). The ignition circuit (1) further includes a second starting circuit (44). The second starting circuit (44) is electrically connected to the squib (83) without passing through the delay circuit (32). The second starting circuit (44) includes a switch (441) connected between the main current path (9) and the squib (83).

[0226] According to this embodiment, the power of the current flowing through the main current path (9) can be used as the power supplied to the squib (83).

[0227] In the ignition circuit (1) of a seventeenth aspect, in any one of the thirteenth to fifteenth aspects, the starting circuit (21) is a first starting circuit (21). The ignition circuit (1) further includes a second starting circuit (44). The second starting circuit (44) is electrically connected to the squib (83) without passing through the delay circuit (32). The second starting circuit (44) includes a coil (442). The coil (442) of the second starting circuit (44) generates a voltage for supplying power to the squib (83) by electromagnetic induction in response to changes in the current flowing through the main electrical circuit (9).

[0228] According to this embodiment, the current flowing through the main current path (9) can be used by the coil (442) to generate the power supplied to the squib (83).

[0229] An interruption system (100) of an eighteenth aspect includes the ignition circuit (1) of any one of the first to seventeenth aspects and a circuit breaker (8).

[0230] According to this embodiment, it is possible to prevent the squib (83) from operating in the event of a momentary overcurrent.

[0231] 100 Breaking system 1 Ignition circuit 21 (First) starting circuit 211 (First) coil 214 Switch 3 First circuit 31 First switch circuit 32 Delay circuit 323 Capacitor 33 Second switch circuit 331 Reed switch 332 First magnetic sensor 34 First determination circuit 4 Second circuit 421 (Second) magnetic sensor 44 Second starting circuit 441 Switch 442 Coil (Second coil) 46 Second determination circuit 520 Magnetic sensor 6 Processor 8 Circuit breaker 81 First terminal 82 Second terminal 83 Squib 834 Explosive powder 84 Projectile 9 Main circuit

Claims

1. An ignition circuit electrically connected to a circuit breaker, the circuit breaker comprising: a first terminal; a second terminal electrically connected to the first terminal; a squib electrically connected to the ignition circuit and containing a gunpowder to be ignited by the ignition circuit; and a projectile that obtains propulsion by combustion of the gunpowder and interrupts the electrical connection between the first terminal and the second terminal, the ignition circuit comprising: a first switch circuit electrically connected to the squib and supplies power to the squib when an input voltage is equal to or higher than a threshold voltage; and a delay circuit electrically connected to the squib via the first switch circuit and delays the supply of power to the squib via the first switch circuit.

2. The ignition circuit of claim 1, wherein the delay circuit includes a capacitor.

3. The ignition circuit according to claim 2, further comprising a second switch circuit which supplies power to said squib when a magnetic field of a certain strength or greater is applied.

4. The ignition circuit according to claim 3, wherein the second switch circuit is electrically connected to the first switch circuit via the delay circuit, and the delay circuit delays the supply of power to the squib via the first switch circuit by delaying the supply of power from the second switch circuit to the first switch circuit.

5. An ignition circuit as claimed in claim 3 or 4, wherein the second switch circuit includes a reed switch, and the reed switch is disposed in an electromagnetic field generated by a current flowing through a main electric circuit electrically connected to the first terminal of the circuit breaker.

6. An ignition circuit as claimed in any one of claims 1 to 5, comprising: a first circuit including said first switch circuit and said delay circuit; and a second circuit electrically connected in parallel with said first circuit, said second circuit supplying power to said squib at an earlier timing than said first circuit when a prescribed condition is satisfied.

7. The ignition circuit according to claim 6, wherein the second circuit includes a magnetic sensor, and the second circuit supplies power to the squib when the strength of a magnetic field applied to the magnetic sensor is equal to or greater than a certain strength.

8. The ignition circuit according to claim 7, wherein the magnetic sensor includes a Hall element, a GMR element, an AMR element, or a reed switch.

9. An ignition circuit as described in claim 6, wherein the first circuit includes a first magnetic sensor, the second circuit includes a second magnetic sensor, the first circuit supplies power to the squib after a delay time set by the delay circuit has elapsed when the intensity of the first magnetic field applied to the first magnetic sensor is equal to or greater than a first intensity threshold, and the second circuit supplies power to the squib at an earlier timing than the first circuit when the intensity of the second magnetic field applied to the second magnetic sensor is equal to or greater than a second intensity threshold that is greater than the first intensity threshold.

10. An ignition circuit as described in claim 6, further comprising a magnetic sensor, wherein the first circuit supplies power to the squib after a delay time set by the delay circuit has elapsed if the intensity of the magnetic field applied to the magnetic sensor is equal to or greater than a first intensity threshold, and the second circuit supplies power to the squib at an earlier timing than the first circuit if the intensity of the magnetic field applied to the magnetic sensor is equal to or greater than a second intensity threshold that is greater than the first intensity threshold.

11. An ignition circuit as claimed in any one of claims 1 to 3, further comprising: a magnetic sensor; a first judgment circuit electrically connected to the first switch circuit via the delay circuit and configured to compare a strength of the magnetic field applied to the magnetic sensor with a first strength threshold; and a second judgment circuit electrically connected to the first switch circuit without the delay circuit and configured to compare a strength of the magnetic field applied to the magnetic sensor with a second strength threshold higher than the first strength threshold, wherein the first judgment circuit causes the first switch circuit to supply power to the squib after a delay time set by the delay circuit has elapsed if the strength of the magnetic field applied to the magnetic sensor is equal to or greater than the first strength threshold, and the second judgment circuit causes the first switch circuit to supply power to the squib if the strength of the magnetic field applied to the magnetic sensor is equal to or greater than the second strength threshold.

12. The ignition circuit according to claim 1, further comprising: a processor including the delay circuit and connected to the first switch circuit; and a magnetic sensor, wherein the processor delays the supply of power to the squib via the first switch circuit by a delay time according to the strength of the magnetic field applied to the magnetic sensor.

13. An ignition circuit as claimed in any one of claims 1 to 12, further comprising a start-up circuit, the start-up circuit using energy of a current flowing in a main current path electrically connected to the first terminal of the breaker to output power to be supplied to the squib, and the delay circuit delays the supply of power to the squib via the first switch circuit by delaying the supply of power from the start-up circuit to the first switch circuit.

14. The ignition circuit according to claim 13, wherein the starting circuit includes a coil, and the coil generates a voltage for supplying power to the squib by electromagnetic induction in response to a change in current flowing through the main current path.

15. The ignition circuit of claim 13, wherein the starter circuit includes a switch connected between the main current path and the delay circuit.

16. An ignition circuit as claimed in any one of claims 13 to 15, wherein the starting circuit is a first starting circuit, and the ignition circuit further comprises a second starting circuit electrically connected to the squib without passing through the delay circuit, and the second starting circuit includes a switch connected between the main current path and the squib.

17. An ignition circuit as claimed in any one of claims 13 to 15, wherein the starting circuit is a first starting circuit, and the ignition circuit further comprises a second starting circuit electrically connected to the squib without passing through the delay circuit, the second starting circuit including a coil, and the coil of the second starting circuit generates a voltage for power supplied to the squib by electromagnetic induction in response to changes in the current flowing through the main current path.

18. A circuit breaker system comprising: an ignition circuit according to any one of claims 1 to 17; and the circuit breaker.

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