Ignition device and breaker system

Abstract

Provided is an ignition device that reduces malfunctions caused by disturbances. An ignition device (A1) is electrically connected to a breaker (50) that includes an explosive and ignites the explosive. The ignition device (A1) comprises a power supply unit (47), a first switch circuit (10), a first magnetic sensor (1) and a second magnetic sensor (2), and a differential circuit (60). The power supply unit (47) generates power in accordance with the magnetic field generated at a principal electrical path that is electrically connected to the breaker (50). The first switch circuit (10) supplies the power to the breaker (50) when the inputted voltage is at or above a first threshold value. The first magnetic sensor (1) and the second magnetic sensor (2) output voltage that corresponds to the strength of the magnetic field generated at the principal electrical path. The voltage outputted from the first magnetic sensor (1) and the second magnetic sensor (2) is inputted to the differential circuit (60), which operates the first switch circuit (10).

Description

Ignition and shutdown systems

[0001] The present disclosure relates generally to ignition devices and interruption systems, and more particularly to ignition devices electrically connected to a circuit breaker and interruption systems including the ignition devices.

[0002] Patent Document 1 discloses an electrical system (interrupter 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] In the electrical system described in Patent Document 1, for example, it may be desirable to reduce malfunctions caused by the influence (disturbance) of magnetic fields, which are external noise.

[0004] Special Publication No. 2023-535020

[0005] An object of the present disclosure is to provide an ignition device and a shutoff system that reduce malfunctions caused by external disturbances.

[0006] An ignition device according to one aspect of the present disclosure is electrically connected to a circuit breaker containing explosives and ignites the explosives. The ignition device includes a power supply unit, a first switch circuit, first and second magnetic sensors, and a differential circuit. The power supply unit generates power in response to a magnetic field generated in a main electric circuit electrically connected to the circuit breaker. The first switch circuit supplies the power to the circuit breaker when an input voltage is equal to or greater than a first threshold. The first and second magnetic sensors output voltages in response to the strength of the magnetic field generated in the main electric circuit. The differential circuit receives the voltages output from the first and second magnetic sensors and operates the first switch circuit.

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

[0008] FIG. 1 is a circuit diagram of an ignition device according to a first embodiment. FIG. 2 is a block diagram of an interruption system including the ignition device according to the first embodiment. FIG. 3 is a perspective view showing the appearance of the ignition device according to the first embodiment. FIG. 4 is a perspective view showing the ignition device according to the first embodiment with a housing removed. FIG. 5 is an explanatory diagram of a magnetic field generated in a main electric circuit of the ignition device according to the first embodiment. FIG. 6 is an explanatory diagram illustrating positions of a first magnetic sensor and a second magnetic sensor of an ignition device according to a modification of the first embodiment. FIG. 7 is an explanatory diagram illustrating positions of a first magnetic sensor and a second magnetic sensor of an ignition device according to another modification of the first embodiment. FIG. 8 is an explanatory diagram illustrating positions of a first magnetic sensor and a second magnetic sensor of an ignition device according to another modification of the first embodiment. FIG. 9 is a circuit diagram of an ignition device according to yet another modification of the first embodiment. FIG. 10 is a circuit diagram of an ignition device according to a second embodiment. FIG. 11 is a circuit diagram of an ignition device according to a third embodiment. FIG. 12 is a circuit diagram of an ignition device according to a modification of the third embodiment. FIG. 13 is a perspective view showing an ignition device according to a fourth embodiment with a housing removed. Fig. 14 is a side view showing an ignition device according to embodiment 5 with a housing removed. Fig. 15 is a side view showing an ignition device according to a modified example of embodiment 5 with a housing removed.

[0009] Below, a description will be given of a shutdown system equipped with an ignition device according to embodiments 1 and 2 with reference to the drawings. The drawings described in each of the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components do not necessarily reflect the actual dimensional ratios. Furthermore, the configurations described in each of the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0010] In the following description, unless otherwise specified, the first direction E1, second direction E2, and third direction E3 indicated by arrows in the drawings are defined as the up-down direction, left-right direction, and front-rear direction of the ignition device of each embodiment. However, the up-down direction, left-right direction, and front-rear direction are used for convenience to facilitate understanding of the description of each embodiment, and do not define the directions when using the ignition device of each embodiment. Furthermore, the arrows indicating "E1," "E2," and "E3" in the drawings are merely shown for the purpose of explanation and do not have any physical substance.

[0011] (First Embodiment) (1) Shutdown System Hereinafter, a shutdown system B1 including an ignition device A1 according to a first embodiment will be described with reference to FIGS. 1 to 5. FIG.

[0012] The interruption system B1 (see FIG. 2 ) is mounted on an object (e.g., a vehicle). The object includes, for example, a main electrical path (e.g., a bus bar) 90 that passes current from a power source 70 to a load 80. The load 80 is, for example, a motor mounted on the vehicle. The power source 70 is, for example, a battery (e.g., a lithium-ion battery) for driving the motor.

[0013] The interruption system B1 is activated, for example, when an overcurrent flows in the main electric circuit 90 of the object, and interrupts the main electric circuit 90 between the power source 70 and the load 80. For example, the interruption system B1 interrupts the main electric circuit 90 in the event of an emergency such as a vehicle abnormality or accident, thereby interrupting the electrical connection between the battery and the motor.

[0014] (2) Components of the Breaker System As shown in FIG. 2, the breaker system B1 includes an ignition device A1 and a breaker 50.

[0015] (2.1) Circuit Breaker The circuit breaker 50 is electrically connected to the ignition device A1. The circuit breaker 50 has a first terminal 51, a second terminal 52, a conductor 53, a squib 54, and a projectile 55.

[0016] The first terminal 51 is electrically connected to the first main electric circuit 91 of the main electric circuit 90. The second terminal 52 is electrically connected to the second main electric circuit 92 of the main electric circuit 90. The second terminal 52 is electrically connected to the first terminal 51 via the conductor 53. In other words, the conductor 53 is electrically connected to the first terminal 51 and the second terminal 52. The conductor 53 is, for example, continuously integrated with the first main electric circuit 91 and the second main electric circuit 92.

[0017] The squib 54 is electrically connected to the ignition device A1. The squib 54 contains explosives that are ignited by the ignition device A1. The projectile 55 obtains impetus from the combustion of the explosives in the squib 54 and interrupts the electrical connection between the first terminal 51 and the second terminal 52. More specifically, the projectile 55 moves toward the conductor 53 and disconnects the conductor 53 from the first terminal 51 and the second terminal 52, thereby interrupting the electrical connection between the first terminal 51 and the second terminal 52.

[0018] In the circuit breaker 50, when the ignition device A1 supplies sufficient power to ignite the gunpowder in the squib 54, the gunpowder in the squib 54 is ignited. The projectile 55 then obtains thrust from the combustion of the gunpowder in the squib 54, and disconnects the conductor 53 from at least one of the first terminal 51 and the second terminal 52, thereby interrupting the main electric circuit 90 (the first main electric circuit 91 and the second main electric circuit 92) between the power source 70 and the load 80.

[0019] (2.2) Ignition Device The ignition device A1 is an ignition device electrically connected to the circuit breaker 50. As shown in FIG. 1 , the ignition device A1 includes a connector 42 (see FIG. 3 ) including a pair of input terminals 49 a, 49 b and a pair of output terminals 4 a, 4 b, a power supply unit 47, and a core 46 (see FIG. 4 ). The power supply unit 47 is, for example, a coil. In the following, to facilitate understanding of the description of the embodiment, the power supply unit 47 will be referred to as the coil 47.

[0020] 1, the ignition device A1 includes a plurality of magnetic sensors 5 (two in the example of FIG. 1), a substrate 43 (see FIG. 4), a housing 40 (see FIG. 3), a first switch circuit 10, a differential circuit 60, and a second switch circuit 20. In this embodiment, the circuit components of the ignition device A1 (the first switch circuit 10, the differential circuit 60, and the second switch circuit 20) are mounted on the substrate 43 of the ignition device A1. The pair of output terminals 4a, 4b are electrically connected to a squib 54 of the circuit breaker 50.

[0021] The pair of input terminals 49a, 49b are mounted on the substrate 43 (see FIGS. 4 and 5). The connector 42 is mounted on the substrate 43 (see FIGS. 4 and 5). The pair of output terminals 4a, 4b are also mounted on the substrate 43. The connector 42 is exposed from one surface of the housing 40 (see FIG. 3). Two magnetic sensors 5 are mounted on the substrate 43 (see FIG. 5). Each magnetic sensor 5 is, for example, a Hall element.

[0022] The substrate 43 is, for example, a printed wiring board. The substrate 43 is plate-shaped (for example, rectangular plate-shaped). The housing 40 houses the coil 47, the core 46, and the substrate 43. The housing 40 is hollow box-shaped. The housing 40 has a through hole (first through hole) 41 through which the main electric circuit 90 is inserted. The first through hole 41 penetrates the housing 40 in the front-rear direction (third direction E3). The first through hole 41 opens in a rectangular shape when viewed from the front in the front-rear direction of the housing 40, for example. As shown in FIG. 3 , the dimension of the first through hole 41 in the left-right direction (second direction E2) of the housing 40 is larger than the dimension of the first through hole 41 in the up-down direction (first direction E1) of the housing 40. In this embodiment, the shape and dimensions of the first through hole 41 approximately match the shape and dimensions of the main electric circuit 90, for example. 3, the main electric circuit 90 has a rectangular parallelepiped shape when viewed from the front in the front-rear direction (third direction E3) of the main electric circuit 90 (see FIG. 5). The shape and dimensions of the first through hole 41 can be changed depending on the shape and dimensions of the main electric circuit 90, for example.

[0023] The core 46 is made of a magnetic material. As shown in FIG. 4 , the core 46 is cylindrical (e.g., rectangular cylindrical). The core 46 includes, for example, a rectangular column-shaped (I-shaped) first core 44 and a U-shaped second core 45. The core 46 has a through-hole (second through-hole) 56 that penetrates in the axial direction, with the front-rear direction of the housing 40 (third direction E3) as the axial direction. In other words, the core 46 has the second through-hole 56 surrounded by the first core 44 and the second core 45. In this embodiment, the shape and dimensions of the second through-hole 56 are approximately the same as, for example, the shape and dimensions of the first through-hole 41 of the housing 40.

[0024] The core 46 is housed in the housing 40 such that the first through-hole 41 of the housing 40 is positioned within the second through-hole 56 of the core 46. As a result, in the ignition device A1, when the main electric circuit 90 is inserted through the first through-hole 41 of the housing 40, the main electric circuit 90 is also inserted through the second through-hole 56 of the core 46.

[0025] The substrate 43 has a through-hole (third through-hole) 57 that penetrates in the axial direction, with the front-rear direction of the housing 40 being the axial direction (see FIG. 5 ). In this embodiment, the shape and dimensions of the third through-hole 57 are substantially the same as, for example, the shape and dimensions of the first through-hole 41 of the housing 40 and the second through-hole 56 of the core 46.

[0026] The substrate 43 is housed in the housing 40 such that the first through-hole 41 of the housing 40 is positioned within the third through-hole 57 of the substrate 43. As a result, in the ignition device A1, when the main electric circuit 90 is inserted into the first through-hole 41 of the housing 40, the main electric circuit 90 is also inserted into the third through-hole 57 of the substrate 43.

[0027] As shown in Fig. 4, a bobbin 48 is attached to the first core 44. The bobbin 48 has electrical insulation properties. A coil 47 is wound around the bobbin 48. In other words, the coil 47 is attached to the first core 44 via the bobbin 48.

[0028] The coil 47, the core 46, and the main electric circuit 90 constitute a transformer. In the ignition device A1, the first through-hole 41 is formed in the housing 40, and the core 46 is provided so as to surround the first through-hole 41. When the main electric circuit 90 is inserted into the first through-hole 41, the main electric circuit 90 and the coil 47 are magnetically coupled. That is, in the ignition device A1, for example, when the current flowing through the main electric circuit 90 changes, the magnetic flux passing through the core 46 changes, and a current (induced current) flows through the coil 47. As a result, the coil 47 generates power in accordance with the induced current. In other words, the coil 47 generates power in accordance with the magnetic field generated by the main electric circuit 90.

[0029] As described above, the ignition device A1 includes the coil 47, the pair of input terminals 49a, 49b, the first switch circuit 10, the second switch circuit 20, and the pair of output terminals 4a, 4b. As shown in Fig. 1 , the ignition device A1 also includes a power supply circuit 6, a protection circuit 30, and a detection circuit 7 including a plurality of magnetic sensors 5 and a differential circuit 60. In this embodiment, the power supply circuit 6, the detection circuit 7, and the protection circuit 30 are mounted on a substrate 43 of the ignition device A1 as circuit components of the ignition device A1.

[0030] 1, the coil 47 is electrically connected to a pair of input terminals 49a and 49b. The input terminal 49a is electrically connected to a first end of the coil 47. The input terminal 49b is electrically connected to a second end of the coil 47.

[0031] The power supply circuit 6 includes two diodes D1 and D2, a Zener diode ZD1, three resistors R1 to R3, two capacitors C2, and a thyristor Q1. The diode D1 is electrically connected between a pair of input terminals 49a and 49b. The anode of the diode D1 is electrically connected to the input terminal 49b. The cathode of the diode D1 is electrically connected to the input terminal 49a. The resistor R1 is electrically connected in parallel with the diode D1.

[0032] A first end of the resistor R1 is electrically connected to the anode of the thyristor Q1. The first end of the resistor R1 is also electrically connected to the anode of the diode D2. The cathode of the diode D2 is electrically connected to the cathode of the Zener diode ZD1. The anode of the Zener diode ZD1 is electrically connected to the gate of the thyristor Q1. The anode of the Zener diode ZD1 is also electrically connected to the cathode of the thyristor Q1 via the resistor R2. The capacitor C1 is electrically connected in parallel with the resistor R2. The capacitor C2 is electrically connected in parallel with the resistor R1. The resistor R3 is electrically connected in parallel with the capacitor C2.

[0033] In the power supply circuit 6, when an induced current flows through the coil 47, a current flows through the diode D2, and if the value of the current flowing through the diode D2 is equal to or greater than a specified value (first specified value), a current flows through the gate of the thyristor Q1, turning the thyristor Q1 on. When the thyristor Q1 turns on, the power supply circuit 6 causes the induced current in the coil 47 to also flow through the thyristor Q1, and outputs the induced current in the coil 47 to the first switch circuit 10. In other words, when the thyristor Q1 turns on, the power supply circuit 6 supplies the power generated in the coil 47 (the power of the coil 47) to the first switch circuit 10.

[0034] In the power supply circuit 6, for example, when the current value of the current flowing through the main electric circuit 90 is small (for example, when the current value of the current flowing through the diode D2 is less than a first specified value), the thyristor Q1 maintains the off state. On the other hand, in the power supply circuit 6, for example, when an overcurrent flows through the main electric circuit 90 to an extent that does not cause a circuit breaker 50 or the like to malfunction (for example, when the current value of the current flowing through the diode D2 is equal to or greater than a first specified value and less than a second specified value, which will be described later), the thyristor Q1 turns on. In addition, in the power supply circuit 6, for example, when an overcurrent flows momentarily through the main electric circuit 90, the thyristor Q1 turns on once, but when the overcurrent stops flowing through the main electric circuit 90, the thyristor Q1 returns to the off state.

[0035] The first switch circuit 10 is disposed between the coil 47 and the circuit breaker 50. When an input voltage (a differential voltage described below) is equal to or greater than a threshold value (a first threshold value), the first switch circuit 10 supplies power to the coil 47 to the circuit breaker 50. The first switch circuit 10 includes a comparator 11, a first setting unit 12, a delay circuit 13, two resistors R4 and R5, a switching element Q2, and a switch (first switch) SW1.

[0036] The inverting input terminal of the comparator 11 is electrically connected to the first setting unit 12. The non-inverting input terminal of the comparator 11 is electrically connected to the differential circuit 60. The output terminal of the comparator 11 is electrically connected to the delay circuit 13. The first setting unit 12 is electrically connected to the input terminal 49b. The first setting unit 12 sets a first threshold value. The delay circuit 13 delays the output of the comparator 11. The delay circuit 13 includes, for example, an electrolytic capacitor.

[0037] A first end of the resistor R4 is electrically connected to the cathode of the thyristor Q1. A second end of the resistor R4 is electrically connected to the delay circuit 13. The second end of the resistor R4 is electrically connected to a first end of the resistor R5. The second end of the resistor R5 is electrically connected to the input terminal 49b.

[0038] The switching element Q2 is, for example, a metal-oxide-semiconductor field effect transistor (MOSFET). More specifically, the switching element Q2 is, for example, a normally-off MOSFET. A first main terminal (for example, a drain terminal) of the switching element Q2 is electrically connected to the first switch SW1. A second main terminal (for example, a source terminal) of the switching element Q2 is electrically connected to a second end of the resistor R5. A control terminal (for example, a gate terminal) of the switching element Q2 is electrically connected to the delay circuit 13.

[0039] The first switch SW1 has two resistors R6 and R7, a transistor Q3, a Zener diode ZD2, a thyristor Q4, and a capacitor C3.

[0040] A first end of the resistor R6 is electrically connected to a first end of the resistor R4. A second end of the resistor R6 is electrically connected to a first main terminal of the switching element Q2. A collector terminal of the transistor Q3 is electrically connected to the first end of the resistor R6. A base terminal of the transistor Q3 is electrically connected to the second end of the resistor R6. An emitter terminal of the transistor Q3 is electrically connected to a cathode of the Zener diode ZD2. An anode of the Zener diode ZD2 is electrically connected to a gate of the thyristor Q4. In addition, an anode of the Zener diode ZD2 is electrically connected to a cathode of the thyristor Q4 via a resistor R7. An anode of the thyristor Q4 is electrically connected to the first end of the resistor R6. A capacitor C3 is electrically connected in parallel with the resistor R7.

[0041] In the first switch circuit 10, when the voltage (differential voltage) from the differential circuit 60 is equal to or greater than a first threshold, the switching element Q2 is turned on. When the switching element Q2 is turned on, the induced current in the coil 47 flows through the resistor R6, turning on the transistor Q3, and the induced current in the coil 47 also flows through the transistor Q3. When the current value of the current flowing through the transistor Q3 is equal to or greater than a specified value (second specified value), the first switch circuit 10 causes current to flow through the gate of the thyristor Q4, turning on the thyristor Q4. The second specified value is greater than the first specified value of the power supply circuit 6. When the thyristor Q4 is turned on, the induced current in the coil 47 also flows through the thyristor Q4, and the first switch circuit 10 outputs the induced current in the coil 47 to the circuit breaker 50. In other words, when the thyristor Q4 is turned on, the first switch circuit 10 supplies power from the coil 47 to the circuit breaker 50.

[0042] For example, when the current value of the current flowing through the main current circuit 90 is a small overcurrent (for example, when the current value of the current flowing through the transistor Q3 is equal to or greater than a first specified value and less than a second specified value), the delay time of the delay circuit 13 becomes longer (the charging time of the delay circuit 13 becomes longer). On the other hand, when the current value of the current flowing through the main current circuit 90 is a large overcurrent (for example, when the current value of the current flowing through the transistor Q3 is equal to or greater than a second specified value), the delay time of the delay circuit 13 becomes shorter (the charging time of the delay circuit 13 becomes shorter).

[0043] That is, if charging of the delay circuit 13 is not completed when the thyristor Q1 of the power supply circuit 6 is in the on state, the first switch circuit 10 maintains the first switch SW1 (thyristor Q4) in the off state. This prevents the ignition device A1 from erroneously interrupting the main electric circuit 90 in the event of an overcurrent that is not due to an emergency, such as a vehicle abnormality or accident. More specifically, even if the thyristor Q1 of the power supply circuit 6 is in the on state, if an overcurrent flows through the main electric circuit 90 to an extent that does not require turning on the first switch SW1, the ignition device A1 can carefully determine the need for interruption based on the delay time of the delay circuit 13, thereby preventing erroneous interruption of the main electric circuit 90. On the other hand, if charging of the delay circuit 13 is completed when the thyristor Q1 of the power supply circuit 6 is in the on state, the first switch circuit 10 turns on the first switch SW1 and supplies power from the coil 47 to the circuit breaker 50. As a result, in the ignition device A1, for example, in the event of a vehicle malfunction, the main electric circuit 90 can be cut off, thereby cutting off the electrical connection between the battery and the motor.

[0044] The protection circuit 30 protects the ignition device A1. For example, when the circuit breaker 50 is interrupted, the protection circuit 30 prevents the induced current of the coil 47 from flowing back to the ignition device A1 or from generating an overvoltage in the ignition device A1, thereby preventing a failure of the ignition device A1. The protection circuit 30 is, for example, a varistor. A first end of the protection circuit 30 is electrically connected to the output terminal 4a. A second end of the protection circuit 30 is electrically connected to the output terminal 4b. That is, the protection circuit 30 is electrically connected between the pair of output terminals 4a and 4b. In other words, the protection circuit 30 is electrically connected in parallel with the circuit breaker 50. The protection circuit 30 is also provided in an electrical path between the first switch circuit 10 and the second switch circuit 20 and the circuit breaker 50. More specifically, the protection circuit 30 is provided in an electrical path between the first switch circuit 10 and the second switch circuit 20 and the pair of output terminals 4a and 4b. As a result, when the circuit breaker 50 is shut off, for example, the induced current of the coil 47 is prevented from flowing back into the ignition device A1 or an overvoltage is prevented from occurring in the ignition device A1, thereby preventing the ignition device A1 from failing.

[0045] The detection circuit 7 detects a magnetic field generated in the main electric circuit 90. The detection circuit 7 includes a resistor R8, a Zener diode ZD3, a plurality of (two in the example of FIG. 1 ) magnetic sensors 5, and a differential circuit 60.

[0046] A first end of the resistor R8 is electrically connected to a first end of the resistor R3 of the power supply circuit 6. The first end of the resistor R8 is also electrically connected to the second switch circuit 20. The second end of the resistor R8 is electrically connected to the two magnetic sensors 5 (the first magnetic sensor 1 and the second magnetic sensor 2). The cathode of the Zener diode ZD3 is electrically connected to the first magnetic sensor 1 and the second magnetic sensor 2. The anode of the Zener diode ZD3 is electrically connected to the second end of the resistor R3 of the power supply circuit 6. The first magnetic sensor 1 and the second magnetic sensor 2 are electrically connected to the differential circuit 60.

[0047] The first magnetic sensor 1 outputs a voltage (detection voltage) corresponding to the strength of the magnetic field generated by the main electric circuit 90. The first magnetic sensor 1 has a surface (detection surface) that detects the magnetic field generated by the main electric circuit 90. The second magnetic sensor 2 is the same magnetic sensor as the first magnetic sensor 1. The first magnetic sensor 1 and the second magnetic sensor 2 are arranged on the substrate 43 facing each other, as shown in FIG. 5 . More specifically, the first magnetic sensor 1 and the second magnetic sensor 2 are arranged side by side along the vertical direction (first direction E1) of the substrate 43, with the main electric circuit 90 sandwiched between them. In other words, the first magnetic sensor 1 is arranged in a position facing the second magnetic sensor 2 across the main electric circuit 90. In this embodiment, the detection surfaces of the first magnetic sensor 1 and the second magnetic sensor 2 face the same direction (leftward in the left-right direction of the substrate 43 in the example of FIG. 5 ). In this embodiment, the distance (first distance) between the first magnetic sensor 1 and the central axis of the third through hole 57 in the substrate 43 is the same as the distance (second distance) between the second magnetic sensor 2 and the central axis of the third through hole 57 in the substrate 43. Note that "same" does not necessarily mean a perfect match, but also includes a deviation of, for example, about 10%. The dotted line with an arrow in Figure 5 indicates the direction of the magnetic field generated in the main electric circuit 90.

[0048] The differential circuit 60 (see FIG. 1 ) receives the voltages (detection voltages) output from the first magnetic sensor 1 and the second magnetic sensor 2, and operates the first switch circuit 10 and the second switch circuit 20. More specifically, the differential circuit 60 outputs a differential voltage between the detection voltage (first detection voltage) output from the first magnetic sensor 1 and the detection voltage (second detection voltage) output from the second magnetic sensor 2 to the first switch circuit 10 and the second switch circuit 20.

[0049] The differential circuit 60 includes a comparator 3 and four resistors R9 to R12. The first terminal of the resistor R9 is electrically connected to the first magnetic sensor 1. The second terminal of the resistor R9 is electrically connected to the non-inverting input terminal of the comparator 3. The first terminal of the resistor R10 is electrically connected to the second magnetic sensor 2. The second terminal of the resistor R10 is electrically connected to the inverting input terminal of the comparator 3. The output terminal of the comparator 3 is electrically connected to the non-inverting input terminal of the comparator 11 of the first switch circuit 10. The output terminal of the comparator 3 is electrically connected to the second switch circuit 20. The first terminal of the resistor R11 is electrically connected to the second terminal of the resistor R10. The second terminal of the resistor R11 is electrically connected to the anode of the Zener diode ZD3. The first terminal of the resistor R12 is electrically connected to the second terminal of the resistor R9. The second terminal of the resistor R12 is electrically connected to the output terminal of the comparator 3.

[0050] The second switch circuit 20 is electrically connected in parallel to the first switch circuit 10. Furthermore, when the input voltage is equal to or greater than a second threshold, the second switch circuit 20 supplies power to the coil 47 to the circuit breaker 50 at an earlier timing than the first switch circuit 10. More specifically, when the voltage (differential voltage) output from the differential circuit 60 is equal to or greater than the second threshold, the second switch circuit 20 supplies power to the coil 47 to the circuit breaker 50 at an earlier timing than the first switch circuit 10. The second threshold is a value greater than the first threshold. The second switch circuit 20 includes a comparator 21, a second setting unit 22, two resistors R13 and R14, a switching element Q5, and a second switch SW2.

[0051] The inverting input terminal of the comparator 21 is electrically connected to the second setting unit 22. The non-inverting input terminal of the comparator 21 is electrically connected to the output terminal of the comparator 3 of the differential circuit 60. The output terminal of the comparator 21 is electrically connected to the switching element Q5. The second setting unit 22 is electrically connected to the second end of the resistor R11 of the differential circuit 60. The second setting unit 22 sets a second threshold value.

[0052] A first end of the resistor R13 is electrically connected to a first end of the resistor R8 of the detection circuit 7. A second end of the resistor R13 is electrically connected to a first end of the resistor R14. A second end of the resistor R14 is electrically connected to a second end of the resistor R11 of the differential circuit 60.

[0053] The switching element Q5 is, for example, a MOSFET. More specifically, the switching element Q5 is a normally-off MOSFET. A first main terminal (e.g., a drain terminal) of the switching element Q5 is electrically connected to the second switch SW2. A second main terminal (e.g., a source terminal) of the switching element Q5 is electrically connected to the second end of the resistor R14. The second main terminal of the switching element Q5 is electrically connected to the output terminal 4b. A control terminal (e.g., a gate terminal) of the switching element Q5 is electrically connected to the output terminal of the comparator 21.

[0054] The second switch SW2 has two resistors R15 and R16, a transistor Q6, a Zener diode ZD4, a thyristor Q7, and a capacitor C4.

[0055] A first end of the resistor R15 is electrically connected to the first end of the resistor R13. A second end of the resistor R15 is electrically connected to the first main terminal of the switching element Q5. A collector terminal of the transistor Q6 is electrically connected to the first end of the resistor R15. A base terminal of the transistor Q6 is electrically connected to the second end of the resistor R15. An emitter terminal of the transistor Q6 is electrically connected to the cathode of the Zener diode ZD4. An anode of the Zener diode ZD4 is electrically connected to the gate of the thyristor Q7. The anode of the Zener diode ZD4 is electrically connected to the cathode of the thyristor Q7 via the resistor R16. The cathode of the thyristor Q7 is electrically connected to the output terminal 4a. The anode of the thyristor Q7 is electrically connected to the first end of the resistor R15. A capacitor C4 is electrically connected in parallel with the resistor R16.

[0056] In the second switch circuit 20, when the differential voltage from the differential circuit 60 is equal to or greater than the second threshold, the switching element Q5 is turned on. When the switching element Q5 is turned on, the induced current in the coil 47 flows through the resistor R15, turning on the transistor Q6, and the induced current in the coil 47 also flows through the transistor Q6. When the current value of the current flowing through the transistor Q6 is equal to or greater than a specified value (third specified value), the second switch circuit 20 allows current to flow through the gate of the thyristor Q7, turning on the thyristor Q7. The third specified value is, for example, the same value as the second specified value of the first switch circuit 10. When the thyristor Q7 is turned on, the induced current in the coil 47 also flows through the thyristor Q7, and the second switch circuit 20 outputs the induced current in the coil 47 to the circuit breaker 50. In other words, when the thyristor Q7 is turned on, the second switch circuit 20 supplies power from the coil 47 to the circuit breaker 50.

[0057] In the second switch circuit 20, for example, when the current value of the current flowing through the main electric circuit 90 is not a large overcurrent (for example, an overcurrent occurring in an emergency such as a vehicle abnormality or accident), the second switch SW2 (thyristor Q7) remains in the off state. On the other hand, in the second switch circuit 20, for example, when the current value of the current flowing through the main electric circuit 90 is a large overcurrent, the second switch SW2 is turned on and supplies power to the coil 47 to the circuit breaker 50. In this way, in the ignition device A1, for example, in an emergency such as a vehicle abnormality or accident, the main electric circuit 90 can be interrupted, and the electrical connection between the battery and the motor can be interrupted.

[0058] In the ignition device A1, when the differential voltage of the differential circuit 60 is equal to or greater than the second threshold, the second switch SW2 (thyristor Q7) is turned on, and the first switch SW1 (thyristor Q4) is also turned on. However, in the ignition device A1, the first switch circuit 10 includes the delay circuit 13, so the second switch circuit 20 can supply power from the coil 47 to the circuit breaker 50 at an earlier timing than the first switch circuit 10. Therefore, in the ignition device A1, the main electric circuit 90 can be immediately interrupted in an emergency, such as a vehicle abnormality or accident.

[0059] In the ignition device A1, as shown in FIG. 5 , the first magnetic sensor 1 and the second magnetic sensor 2 are arranged on the substrate 43 facing the same direction, and are spaced the same distance from the central axis of the third through-hole 57 of the substrate 43. Therefore, the voltage value of the first detected voltage caused by an overcurrent flowing in the main electric circuit 90 (the portion passing through the third through-hole 57 of the substrate 43) in the first magnetic sensor 1 is approximately the same as the voltage value of the second detected voltage caused by an overcurrent flowing in the main electric circuit 90 in the second magnetic sensor 2. Furthermore, the polarity of the first detected voltage is opposite (reverse polarity) to the polarity of the second detected voltage. For example, when the voltage value of the first detected voltage in the first magnetic sensor 1 is +A, the voltage value of the second detected voltage in the second magnetic sensor 2 is −A.

[0060] 1, in the ignition device A1, the first detection voltage from the first magnetic sensor 1 is applied to the non-inverting input terminal of the comparator 3 of the differential circuit 60, and the second detection voltage from the second magnetic sensor 2 is applied to the inverting input terminal of the comparator 3. Therefore, in the ignition device A1, the voltage value of the voltage (differential voltage) from the output terminal of the comparator 3 is 2 A.

[0061] Incidentally, for example, if there is another main electric circuit near the main electric circuit 90, the ignition device A1 may be affected by the magnetic field generated by the other main electric circuit. However, since the ignition device A1 is equipped with a plurality of magnetic sensors 5 (first magnetic sensor 1 and second magnetic sensor 2) and a differential circuit 60, it is possible to cancel out the influence of the magnetic field generated by the other main electric circuit.

[0062] Specifically, in the ignition device A1, for example, if another main electric circuit is arranged in one direction (e.g., downward) of the vertical direction (first direction E1) of the circuit board 43, when the ignition device A1 is affected by a magnetic field (e.g., +B) generated by the other main electric circuit, the voltage value of the first detected voltage from the first magnetic sensor 1 is A+B, and the voltage value of the second detected voltage from the second magnetic sensor 2 is −A+B. Therefore, the voltage value of the differential voltage from the output terminal of the comparator 3 is (A+B)−(−A+B), or 2A. In other words, even if another main electric circuit is arranged near the main electric circuit 90, the ignition device A1 can cancel the influence (disturbance) of the magnetic field generated by the other main electric circuit, thereby reducing malfunctions caused by the disturbance. Therefore, the interruption system B1 equipped with the ignition device A1 also reduces malfunctions caused by the disturbance.

[0063] (3) Modifications The ignition device A1 includes the second switch circuit 20, but may not include the second switch circuit 20. In this case, the first switch circuit 10 does not need to include the delay circuit 13. Furthermore, the ignition device A1 includes the power supply circuit 6, but may not include the power supply circuit 6.

[0064] The power supply unit 47 is not limited to a coil, and may be, for example, a semiconductor relay connectable to a power generating element such as a capacitor, a battery, or a Peltier element. The power supply unit 47 may also be, for example, a reed switch connectable to a power generating element such as a capacitor, a battery, or a Peltier element. If the power supply unit 47 is, for example, a semiconductor relay connectable to a capacitor or a battery, the semiconductor relay may be turned on and off by the output of a magnetic sensor (e.g., a Hall element). If a battery is used as the power supply unit 47, the power supply unit 47 may be provided separately from the ignition device A1. For example, the power supply unit 47 may use a battery for driving a vehicle motor as its power source.

[0065] As shown in Fig. 5, the first magnetic sensor 1 and the second magnetic sensor 2 are arranged side by side in the vertical direction (first direction E1) of the substrate 43 with the main electric circuit 90 sandwiched between them, but as shown in Fig. 6, for example, they may be arranged side by side in the horizontal direction (second direction E2) of the substrate 43 with the main electric circuit 90 sandwiched between them. In this case, the detection surfaces of the first magnetic sensor 1 and the second magnetic sensor 2 face, for example, upward in the vertical direction of the substrate 43. In this case, the other main electric circuit is arranged in one direction (for example, the right direction) of the horizontal direction (second direction E2) of the substrate 43.

[0066] Furthermore, the first magnetic sensor 1 and the second magnetic sensor 2 may be arranged side by side along a first side of the main electric circuit 90 (in the example of FIG. 7 , the long side of the main electric circuit 90), as shown in FIG. 7 . In other words, the first magnetic sensor 1 and the second magnetic sensor 2 may be arranged side by side along a first side of the third through hole 57 (in the example of FIG. 7 , the long side of the third through hole 57). In other words, the first magnetic sensor 1 may be arranged in a first direction as viewed from the main electric circuit 90 (in the example of FIG. 7 , the downward direction of the substrate 43). The second magnetic sensor 2 may be arranged in the first direction as viewed from the main electric circuit 90. In this case, the detection surfaces of the first magnetic sensor 1 and the second magnetic sensor 2 face, for example, upward on the substrate 43. In this case, the other main electric circuits are arranged in one left-right direction (for example, the right direction) of the substrate 43.

[0067] 7, the first magnetic sensor 1 and the second magnetic sensor 2 are disposed near one of the two long sides of the third through hole 57, but they may be disposed near the other of the two long sides. That is, the first magnetic sensor 1 may be disposed above the substrate 43 when viewed from the main electric circuit 90. The second magnetic sensor 2 may be disposed above the substrate 43 when viewed from the main electric circuit 90.

[0068] Furthermore, the first magnetic sensor 1 and the second magnetic sensor 2 may be arranged side by side along the second side of the main electric circuit 90 (the short side of the main electric circuit 90 in the example of FIG. 8 ), for example, as shown in FIG. 8 . In other words, the first magnetic sensor 1 and the second magnetic sensor 2 may be arranged side by side along the second side of the third through hole 57 (the short side of the third through hole 57 in the example of FIG. 8 ). In other words, the first magnetic sensor 1 may be arranged to the right of the substrate 43 as viewed from the main electric circuit 90. The second magnetic sensor 2 may be arranged to the right of the substrate 43 as viewed from the main electric circuit 90. In this case, the detection surfaces of the first magnetic sensor 1 and the second magnetic sensor 2 face, for example, leftward in the left-right direction of the substrate 43. In this case, the other main electric circuits are arranged in one direction (e.g., downward) in the up-down direction of the substrate 43.

[0069] 8, the first magnetic sensor 1 and the second magnetic sensor 2 are disposed near one of the two short sides of the third through hole 57, but they may be disposed near the other of the two short sides. That is, the first magnetic sensor 1 may be disposed to the left of the substrate 43 when viewed from the main electric circuit 90. The second magnetic sensor 2 may be disposed to the left of the substrate 43 when viewed from the main electric circuit 90.

[0070] The first magnetic sensor 1 and the second magnetic sensor 2 are preferably positioned so as to overlap the main electric circuit 90, as shown in FIG. 7 . More specifically, the first magnetic sensor 1 is preferably positioned inward (leftward) of the right side of the main electric circuit 90, and the second magnetic sensor 2 is preferably positioned inward (rightward) of the left side of the main electric circuit 90. This allows the ignition device A1 to shorten the distance between the first magnetic sensor 1 and the second magnetic sensor 2 and a disturbance magnetic field compared to when the main electric circuit 90 is sandwiched between the first magnetic sensor 1 and the second magnetic sensor 2. Therefore, the ignition device A1 can reduce the error between the influence of the disturbance magnetic field on the first magnetic sensor 1 and the influence of the disturbance magnetic field on the second magnetic sensor 2. As a result, the ignition device A1 further reduces malfunctions caused by disturbances. In particular, the ignition device A1 is most effective because it is less susceptible to the effects of disturbance magnetic fields when the first magnetic sensor 1 and the second magnetic sensor 2 are positioned so as to overlap the entire main electric circuit 90, as shown in Fig. 7. Furthermore, the ignition device A1 is also effective because it is less susceptible to the effects of disturbance magnetic fields even when the first magnetic sensor 1 and the second magnetic sensor 2 are positioned so as to overlap a portion of the main electric circuit 90, as shown in Fig. 8.

[0071] It is preferable that the distance between the center of the main electric circuit 90 and the center of the first magnetic sensor 1 (the center of the detection surface of the first magnetic sensor 1) and the distance between the center of the main electric circuit 90 and the center of the second magnetic sensor 2 (the center of the detection surface of the second magnetic sensor 2) are equal, as shown in Fig. 7. This further reduces malfunctions of the ignition device A1 due to disturbances.

[0072] Furthermore, it is preferable that the angle formed by the line segment connecting the center of the main electric circuit 90 to the center of the first magnetic sensor 1 (the center of the detection surface of the first magnetic sensor 1) and the line segment connecting the center of the main electric circuit 90 to the center of the second magnetic sensor 2 (the center of the detection surface of the second magnetic sensor 2) is 90 degrees. This further reduces malfunctions of the ignition device A1 due to external disturbances.

[0073] The protection circuit 30 is not limited to a varistor, and may be, for example, a Zener diode as shown in Fig. 9. In this case, the anode of the Zener diode is electrically connected to the output terminal 4b, and the cathode of the Zener diode is electrically connected to the output terminal 4a.

[0074] The protection circuit 30 may be a protection circuit (e.g., a snubber circuit) including a resistor and a capacitor. Examples of the snubber circuit include an RC snubber circuit, a non-charging type RCD snubber circuit, and a charging type RCD snubber circuit.

[0075] 2 is configured such that when the explosive in the squib 54 is ignited, the projectile 55 disconnects the conductor 53 from at least one of the first terminal 51 and the second terminal 52. However, the configuration is not limited to this. The circuit breaker 50 may be configured, for example, such that the conductor 53 is movable between a position where the conductor 53 is connected to the first terminal 51 and the second terminal 52 (connected position) and a position where the conductor 53 is not connected to the first terminal 51 or the second terminal 52 (disconnected position), and such that when the explosive in the squib 54 is ignited, the projectile 55 moves the conductor 53 from the connected position to the disconnected position. In short, the circuit breaker 50 may be configured in any way as long as it can interrupt the electrical connection between the power source 70 and the load 80 when the explosive in the squib 54 is ignited.

[0076] The object in which the shutdown system B1 is installed is not limited to a vehicle, but may be, for example, a home appliance, a solar power generation system, or the like.

[0077] (Embodiment 2) As shown in Fig. 10, an ignition device A2 according to embodiment 2 differs from the ignition device A1 according to embodiment 1 (see Figs. 1 to 5) in that the second switch circuit 20 does not have a second switch SW2. Note that, with respect to the ignition device A2 according to embodiment 2, components similar to those of the ignition device A1 according to embodiment 1 are denoted by the same reference numerals and description thereof will be omitted. The shutoff system B1 according to embodiment 2 includes an ignition device A2 instead of the ignition device A1. That is, the shutoff system B1 according to embodiment 2 includes an ignition device A2 and a circuit breaker 50.

[0078] (1) Ignition Device As described above, the second switch circuit 20 does not have the second switch SW2 of the ignition device A1 (see FIG. 1). That is, in the ignition device A2, the second switch circuit 20 does not have the second switch SW2, but instead uses the first switch SW1 of the first switch circuit 10 as shown in FIG.

[0079] A first main terminal (for example, a drain terminal) of the switching element Q5 is electrically connected to a first main terminal (for example, a drain terminal) of the switching element Q2 of the first switch circuit 10.

[0080] As with the ignition device A1 of the first embodiment, the ignition device A2 includes multiple magnetic sensors 5 (first magnetic sensor 1 and second magnetic sensor 2) and a differential circuit 60, making it possible to cancel out the effects of magnetic fields generated in other main electrical circuits. Therefore, the ignition device A2 also reduces malfunctions caused by disturbances. Therefore, the shutdown system B1 including the ignition device A2 also reduces malfunctions caused by disturbances.

[0081] Furthermore, in the ignition device A2, the second switch circuit 20 utilizes the first switch SW1 of the first switch circuit 10 and does not have the second switch SW2 of the ignition device A1, so it is possible to make the ignition device A2 smaller than the ignition device A1.

[0082] (2) Modifications As a modification of the second embodiment, modifications similar to those of the ignition device A1 according to the modification of the first embodiment are possible. Therefore, the ignition device A2 according to the modification of the second embodiment also achieves the same effects as the ignition device A2 according to the second embodiment.

[0083] (Embodiment 3) As shown in Figure 11, an ignition device A3 according to embodiment 3 differs from the ignition device A1 according to embodiment 1 (see Figures 1 to 5) in that it includes a control device 100 having a differential circuit 60. Note that, with respect to the ignition device A3 according to embodiment 3, components similar to those of the ignition device A1 according to embodiment 1 are denoted by the same reference numerals and description thereof will be omitted. The shutoff system B1 according to embodiment 3 includes an ignition device A3 instead of the ignition device A1. That is, the shutoff system B1 according to embodiment 3 includes an ignition device A3 and a circuit breaker 50.

[0084] (1) Ignition Device The ignition device A3 includes, for example, as shown in FIG. 11 , a power supply device 101, a first switch circuit 10, a pair of output terminals 4 a, 4 b, a protection circuit 30, a plurality of (two in the example of FIG. 11 ) magnetic sensors 5, and a control device 100.

[0085] The power supply device 101 includes, for example, a power supply unit 47 (see FIG. 1), a pair of input terminals 49a and 49b (see FIG. 1), and a power supply circuit 6 (see FIG. 1).

[0086] The control device 100 is realized, for example, by a computer system having one or more processors and one or more memories. In other words, the functions of the control device 100 are realized by the one or more processors executing a program recorded in the memory. The program may be pre-recorded in the memory, may be provided via a telecommunications line such as the Internet, or may be recorded on a non-transitory recording medium such as a memory card and provided.

[0087] The control device 100 is, for example, an ECU (Electronic Control Unit) mounted on a vehicle. The control device 100 has a differential circuit 60. The control device 100 is electrically connected to a first switch circuit 10. The control device 100 is also electrically connected to a plurality of magnetic sensors 5 (first magnetic sensors 1 and second magnetic sensors 2).

[0088] The control device 100 controls the first switch circuit 10 based on the output voltage (differential voltage) of the comparator 3 (see FIG. 1 ) in the differential circuit 60. For example, when the differential voltage of the differential circuit 60 is equal to or greater than a first threshold, the control device 100 controls the first switch circuit 10 so that the switching element Q2 (see FIG. 1 ) of the first switch circuit 10 is turned on. Furthermore, when the differential voltage of the differential circuit 60 is less than the first threshold, the control device 100 controls the first switch circuit 10 so that the switching element Q2 remains off. Specifically, when the differential voltage of the differential circuit 60 is equal to or greater than the first threshold, the control device 100 supplies the differential voltage of the differential circuit 60 to the non-inverting input terminal of the comparator 11 (see FIG. 1 ) in the first switch circuit 10. When the differential voltage of the differential circuit 60 is less than the first threshold, the control device 100 does not supply the differential voltage of the differential circuit 60 to the non-inverting input terminal of the comparator 11 in the first switch circuit 10.

[0089] Therefore, like the ignition device A1 of the first embodiment, the ignition device A3 includes multiple magnetic sensors 5 (first magnetic sensor 1 and second magnetic sensor 2) and a differential circuit 60, making it possible to cancel out the effects of magnetic fields generated in other main electrical circuits. Therefore, the ignition device A3 also reduces malfunctions caused by disturbances. Therefore, the shutdown system B1 including the ignition device A3 also reduces malfunctions caused by disturbances.

[0090] Furthermore, in the ignition device A3, the differential circuit 60 is provided in an ECU (control device 100 in the example of FIG. 11) mounted on the vehicle. In other words, the function of the differential circuit 60 can be realized by the ECU, resulting in a simpler configuration than the ignition device A1 of embodiment 1.

[0091] (2) Modification The ignition device A3 may further include the second switch circuit 20 (see FIG. 1 ) of the first embodiment in addition to the first switch circuit 10. In this case, the second switch circuit 20 is electrically connected in parallel with the first switch circuit 10, and the control device 100 is electrically connected to the non-inverting input terminal of the comparator 21 (see FIG. 1 ) of the second switch circuit 20. The control device 100 controls the second switch circuit 20 based on the differential voltage of the differential circuit 60, similar to the case of controlling the first switch circuit 10.

[0092] The power supply device 101 uses a coil as the power supply unit 47, but may also use a power generating element such as a capacitor that is capacitively coupled to the main electric circuit 90. In this case, the power supply device 101 may include a capacitor that stores the power generated by the power generating element.

[0093] The power supply device 101 may also use, as the power supply unit 47, for example, a power supply 70 (see FIG. 2 ) electrically connected to the main electric circuit 90. In this case, it is preferable that the power supply device 101 has, for example, a step-down circuit provided in the electric circuit between the power supply 70 and the power supply circuit 6.

[0094] Furthermore, the power supply device 101 may use a power supply (hereinafter referred to as an “another power supply”) separate from the power supply 70 as the power supply unit 47. In this case, it is preferable that the output voltage or output current of the separate power supply is lower than the output voltage or output current of the power supply 70.

[0095] The ignition device A3 may include a switch such as a semiconductor relay or a MOSFET instead of the first switch circuit 10. The ignition device A3 may also include a reed switch instead of the first switch circuit 10.

[0096] In the ignition device A3, for example, as shown in FIG. 12 , the control device 100 may not include the differential circuit 60. In this case, the ignition device A3 includes a sensor 102 that detects an overcurrent flowing in the main electric circuit 90 in the event of an emergency, such as a vehicle abnormality or accident, instead of the multiple magnetic sensors 5 (first magnetic sensor 1 and second magnetic sensor 2). That is, the ignition device A3 includes, for example, a power supply device 101, a first switch circuit 10, a pair of output terminals 4 a, 4 b, a protection circuit 30, the sensor 102, and the control device 100. Note that the modified ignition device A3 shown in FIG. 12 may further include a second switch circuit 20. The number of sensors 102 may be one or more. The sensor 102 may include the first magnetic sensor 1 and the second magnetic sensor 2.

[0097] The control device 100 of the modified ignition device A3 shown in Fig. 12 controls the first switch circuit 10 so that the switching element Q2 (see Fig. 1) of the first switch circuit 10 is turned on when an overcurrent is detected by the sensor 102. In other words, when an overcurrent is detected by the sensor 102, the control device 100 controls the first switch circuit 10 so that power from the power supply unit 47 is supplied to the circuit breaker 50. As a result, the modified ignition device A3 can interrupt the main electric circuit 90 in the event of an emergency such as a vehicle abnormality or accident, and can thereby interrupt the electrical connection between the battery and the motor.

[0098] 12, in the ignition device A3 of the modified example, the protection circuit 30 is electrically connected in parallel with the circuit breaker 50. As a result, in the ignition device A3 of the modified example, for example, when the circuit breaker 50 is interrupted, it is possible to suppress the induced current of the power supply unit 47 (see FIG. 1) of the power supply device 101 from flowing back into the ignition device A3 or the occurrence of an overvoltage in the ignition device A3, thereby preventing the ignition device A3 from failing.

[0099] (Fourth Embodiment) As shown in FIG. 13, an ignition device A4 according to the fourth embodiment differs from the ignition device A1 according to the first embodiment (see FIGS. 1 to 5) in that it further includes a magnetic shield 31. Note that, with respect to the ignition device A4 according to the fourth embodiment, components similar to those of the ignition device A1 according to the first embodiment are denoted by the same reference numerals and will not be described again. The interruption system B1 according to the fourth embodiment includes an ignition device A4 instead of the ignition device A1. That is, the interruption system B1 according to the fourth embodiment includes an ignition device A4 and a circuit breaker 50. Note that in FIG. 13, the housing 40 is not shown to facilitate understanding of the description of the embodiment.

[0100] (1) Ignition Device The ignition device A4 further includes, for example, a plurality of magnetic shields 31 (two in the example of FIG. 13).

[0101] Each of the magnetic shields 31 absorbs a magnetic field (magnetic flux) generated externally (for example, from another main current path). In other words, each of the magnetic shields 31 prevents the externally generated magnetic field from entering the magnetic sensors 5 (the first magnetic sensor 1 and the second magnetic sensor 2).

[0102] Each of the magnetic shields 31 has a plate shape (for example, a rectangular plate shape) and is made of a magnetic material such as iron or an alloy containing iron.

[0103] The multiple magnetic shields 31 are arranged, for example, facing each other. More specifically, the multiple magnetic shields 31 are arranged, for example, side by side along the left-right direction (second direction E2) of the substrate 43, with the multiple magnetic sensors 5, main electric circuit 90, and substrate 43 sandwiched therebetween. The multiple magnetic shields 31 are sandwiched, for example, between the housing 40 and the substrate 43. Note that the multiple magnetic shields 31 are not electrically connected to the housing 40 or the substrate 43.

[0104] Therefore, in the ignition device A4, even if another main electric circuit is placed near the main electric circuit 90 (for example, if the other main electric circuit is placed to the right or left of the main electric circuit 90), the multiple magnetic shields 31 can prevent the magnetic fields generated by the other main electric circuits from entering the multiple magnetic sensors 5, thereby further reducing malfunctions caused by disturbances. Therefore, the interruption system B1 equipped with the ignition device A4 also further reduces malfunctions caused by disturbances.

[0105] (2) Modification The multiple magnetic shields 31 are sandwiched between the housing 40 and the substrate 43, but may be fixed to the substrate 43 via a holding member (not shown), or may be fixed to the inner surface of the housing 40, for example.

[0106] The number of magnetic shields 31 is not limited to two and may be three. For example, one of the three magnetic shields 31 may be disposed between the lower end of the substrate 43 in the up-down direction (first direction E1) and the bottom wall of the housing 40. Furthermore, the number of magnetic shields 31 is not limited to two and may be one.

[0107] (Fifth Embodiment) As shown in FIG. 14, an ignition device A5 according to a fifth embodiment differs from the ignition device A1 according to the first embodiment (see FIGS. 1 to 5) in that it further includes a magnetic shield 32. Note that, with respect to the ignition device A5 according to the fifth embodiment, components similar to those of the ignition device A1 according to the first embodiment are denoted by the same reference numerals and will not be described again. The interruption system B1 according to the fifth embodiment includes an ignition device A5 instead of the ignition device A1. That is, the interruption system B1 according to the fifth embodiment includes an ignition device A5 and a circuit breaker 50. Note that in FIG. 14, the housing 40 is not shown to facilitate understanding of the description of the embodiments.

[0108] (1) Ignition Device The ignition device A5 further includes, for example, a plurality of magnetic shields 32 (two in the example of FIG. 14).

[0109] Each of the multiple magnetic shields 32 absorbs the magnetic field (magnetic flux) generated by the coil 47 (see FIG. 4 ) and the core 46. In other words, each of the multiple magnetic shields 32 prevents the magnetic field generated by the coil 47 and the core 46 from entering the multiple magnetic sensors 5.

[0110] Each of the magnetic shields 32 has a plate shape (for example, a rectangular plate shape) and is made of a magnetic material such as iron or an alloy containing iron.

[0111] The multiple magnetic shields 32 include a first magnetic shield 33 and a second magnetic shield 34. The first magnetic shield 33 is disposed, for example, between a bobbin 48 around which a coil 47 is wound and a core 46 (hereinafter referred to as a "power generating device 103") and a substrate 43, and is also disposed between the first magnetic sensor 1 and the power generating device 103. The second magnetic shield 34 is disposed, for example, between the power generating device 103 and the substrate 43, and is also disposed between the second magnetic sensor 2 and the power generating device 103.

[0112] The first magnetic shield 33 is fixed to the substrate 43 via, for example, a first holding member (not shown). The second magnetic shield 34 is fixed to the substrate 43 via, for example, a second holding member (not shown). The first magnetic shield 33 and the second magnetic shield 34 are not electrically connected to the substrate 43.

[0113] Therefore, in the ignition device A5, even if a magnetic field is generated in the coil 47 and the core 46, the magnetic shields 32 can prevent the magnetic field generated in the coil 47 and the core 46 from entering the magnetic sensors 5, thereby further reducing malfunctions caused by disturbances. Therefore, the interruption system B1 including the ignition device A5 also further reduces malfunctions caused by disturbances.

[0114] (2) Modification Each of the magnetic shields 32 is plate-shaped, but may be L-shaped, as shown in Fig. 15. Note that in Fig. 15 as well, the housing 40 is not shown to facilitate understanding of the description of the embodiment.

[0115] The first magnetic shield 33 includes a first piece 33 a and a second piece 33 b. The first piece 33 a of the first magnetic shield 33 is disposed, for example, between the power generation device 103 and the substrate 43, and between the first magnetic sensor 1 and the power generation device 103. The second piece 33 b of the first magnetic shield 33 is disposed, for example, along the front-rear direction of the core 46 (third direction E3), and is disposed so as to face the first core 44 and the bobbin 48.

[0116] The second magnetic shield 34 includes a first piece 34a and a second piece 34b. The first piece 34a of the second magnetic shield 34 is disposed, for example, between the power generation device 103 and the substrate 43, and between the second magnetic sensor 2 and the power generation device 103. The second piece 34b of the second magnetic shield 34 is disposed, for example, along the front-rear direction of the core 46, and is disposed so as to face the second core 45.

[0117] Furthermore, each of the plurality of magnetic shields 32 may be, for example, U-shaped. That is, each of the plurality of magnetic shields 32 is configured to cover at least a portion of the bobbin 48 around which the coil 47 is wound and the core 46 in order to prevent the magnetic field generated by the coil 47 and the core 46 from entering the plurality of magnetic sensors 5.

[0118] The above-described first to fifth embodiments and modifications are merely a part of the various embodiments and modifications of the present disclosure.

[0119] The present disclosure is not limited to the above-described embodiments, and at least some of the configurations of the embodiments and modified examples can be combined as appropriate and applied.

[0120] (Aspects) The present specification discloses the following aspects.

[0121] An ignition device (A1 to A5) according to a first aspect is electrically connected to a circuit breaker (50) containing explosives and ignites the explosives. The ignition device (A1 to A5) includes a power supply unit (47), a first switch circuit (10), a first magnetic sensor (1), a second magnetic sensor (2), and a differential circuit (60). The power supply unit (47) generates power in response to a magnetic field generated in a main electric circuit (90) electrically connected to the circuit breaker (50). The first switch circuit (10) supplies the power to the circuit breaker (50) when an input voltage is equal to or greater than a first threshold. The first magnetic sensor (1) and the second magnetic sensor (2) output a voltage in response to the strength of the magnetic field generated in the main electric circuit (90). The differential circuit (60) receives the voltages output from the first magnetic sensor (1) and the second magnetic sensor (2) and operates the first switch circuit (10).

[0122] According to this aspect, malfunctions caused by disturbances are reduced.

[0123] The ignition device (A1 to A5) according to the second aspect is the same as the first aspect, and further includes a second switch circuit (20). The second switch circuit (20) is connected in parallel to the first switch circuit (10). When the input voltage is equal to or greater than a second threshold value that is greater than the first threshold value, the second switch circuit (20) supplies the power to the breaker (50) at an earlier timing than the first switch circuit (10).

[0124] According to this aspect, malfunctions caused by external disturbances are reduced, and the main electric circuit (90) can be quickly shut off in the event of an emergency such as a vehicle malfunction or accident.

[0125] In the ignition device (A1 to A5) according to the third aspect, in the first or second aspect, the first magnetic sensor (1) is arranged in a position opposite the second magnetic sensor (2) across the main electric circuit (90).

[0126] According to this aspect, malfunctions caused by disturbances are further reduced.

[0127] In the ignition device (A1 to A5) according to the fourth aspect, in the first or second aspect, the first magnetic sensor (1) is arranged in a first direction as viewed from the main electric circuit (90). The second magnetic sensor (2) is arranged in the first direction as viewed from the main electric circuit (90).

[0128] According to this aspect, malfunctions caused by disturbances are further reduced.

[0129] In the ignition device (A1 to A5) according to the fifth aspect, in the fourth aspect, the first magnetic sensor (1) and the second magnetic sensor (2) are arranged in a position overlapping with the main electric circuit (90).

[0130] According to this aspect, malfunctions caused by disturbances are further reduced.

[0131] A circuit breaker system (B1) according to a sixth aspect includes the ignition device (A1 to A5) according to any one of the first to fifth aspects, and a circuit breaker (50).

[0132] According to this aspect, malfunctions caused by disturbances are reduced.

[0133] An ignition device (A3 to A5) according to a seventh aspect is electrically connected to a circuit breaker (50) containing explosives and ignites the explosives. The ignition device (A3 to A5) includes a power supply unit (47), a first switch circuit (10), a sensor (102), a control device (100), and a protection circuit (30). The sensor (102) detects an overcurrent flowing in the main electrical circuit (90). When the sensor (102) detects an overcurrent, the control device (100) controls the first switch circuit (10) to supply power from the power supply unit (47) to the circuit breaker (50). The protection circuit (30) protects the ignition device (A3 to A5). The protection circuit (30) is connected in parallel with the circuit breaker (50).

[0134] According to this aspect, for example, when the circuit breaker (50) is interrupted, it is possible to prevent the induced current of the power supply unit (47) from flowing back to the ignition devices (A3 to A5) or to prevent overvoltage from occurring in the ignition devices (A3 to A5), thereby preventing the ignition devices (A3 to A5) from breaking down.

[0135] An ignition device (A3 to A5) according to an eighth aspect is the seventh aspect, wherein the sensor (102) includes a first magnetic sensor (1) and a second magnetic sensor (2). Each of the first magnetic sensor (1) and the second magnetic sensor (2) outputs a voltage corresponding to the strength of a magnetic field generated in the main electric circuit (90). The control device (100) has a differential circuit (60). The differential circuit (60) receives the voltages output from the first magnetic sensor (1) and the second magnetic sensor (2) and operates the first switch circuit (10).

[0136] REFERENCE SIGNS LIST 1 First magnetic sensor 2 Second magnetic sensor 5 Magnetic sensor 10 First switch circuit 20 Second switch circuit 30 Protection circuit 47 Coil (power supply unit) 50 Circuit breaker 60 Differential circuit 90 Main current path 100 Control device 102 Sensor A1 to A5 Ignition device B1 Breaker system

Claims

1. An ignition device electrically connected to a circuit breaker containing explosives to ignite the explosives, comprising: a power supply unit that generates power in response to a magnetic field generated in a main electric circuit electrically connected to the circuit breaker; a first switch circuit that supplies the power to the circuit breaker when an input voltage is equal to or greater than a first threshold; first and second magnetic sensors that output a voltage in response to the strength of the magnetic field generated in the main electric circuit; and a differential circuit that receives the voltage output from the first and second magnetic sensors and operates the first switch circuit.

2. The ignition device according to claim 1, further comprising a second switch circuit connected in parallel to the first switch circuit and supplying the power to the circuit breaker at an earlier timing than the first switch circuit when an input voltage is equal to or greater than a second threshold value that is greater than the first threshold value.

3. An ignition device according to claim 1 or claim 2, wherein the first magnetic sensor is disposed in a position facing the second magnetic sensor across the main electric circuit.

4. An ignition device according to claim 1 or claim 2, wherein the first magnetic sensor is arranged in a first direction as viewed from the main electric circuit, and the second magnetic sensor is arranged in the first direction as viewed from the main electric circuit.

5. The ignition device according to claim 4, wherein the first magnetic sensor and the second magnetic sensor are arranged in positions overlapping the main electric circuit.

6. A circuit breaker system comprising: an ignition device according to any one of claims 1 to 5; and the circuit breaker.

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