JP4192779B2 - Ignition device - Google Patents

Description

  The present invention relates to an ignition device including a plurality of squibs.

Examples of the airbag device include a device that changes the internal pressure of the bag, a device that changes the capacity of the bag by changing the internal pressure, and a device that includes a plurality of bags. Such an air bag device includes an inflator device including a plurality of inflators (gas generation chambers), and each inflator generates a gas to cope with changes in the internal pressure of the back and a plurality of backs. This inflator device includes an ignition circuit in which squibs corresponding to each inflator are connected in parallel. When a certain squib ignites, gas is generated by the corresponding inflator (see Patent Document 1). Therefore, the ECU [Electronic Control Unit] performs ignition control for a plurality of squibs, and supplies an ignition current to each squib.
JP 2003-226223 A Japanese Patent Laid-Open No. 10-157560 JP-A-9-58400

  However, in the case of an ignition circuit in which a plurality of squibs are connected in parallel, current must be supplied from the ECU to each squib, and therefore, wiring between the ECU and the ignition circuit is required for the number of squibs. Therefore, the large number of wirings increase weight and cost. In addition, man-hours for securing wiring space and mounting are also required.

  Then, this invention makes it a subject to provide the ignition device which does not require wiring for the number of squibs, when providing a several squib.

An ignition device according to the present invention includes a plurality of squibs connected in parallel and a plurality of resonance frequency circuits respectively connected to the plurality of squibs and having different resonance frequencies for each squib, and any squib among the plurality of squibs Is ignited, a current having the same frequency as the resonance frequency of the resonance frequency circuit connected to the arbitrary squib is supplied to a parallel circuit including a plurality of squibs connected in parallel and the resonance frequency circuit .

  In this ignition device, a plurality of squibs are connected in parallel, and a resonance frequency circuit is connected to each squib. Each resonance frequency circuit is a circuit having a different resonance frequency for each squib. When a current having the same frequency as the resonance frequency is supplied, the current flows, and when any other current is supplied, the current flow is cut off. . Therefore, in order to ignite an arbitrary squib, a current having the same frequency as the resonance frequency of the resonance frequency circuit connected to the squib must be supplied. That is, only a specific squib can be ignited by supplying a current having the same frequency as the resonance frequency in the circuit in which the squibs are connected in parallel. Therefore, when the control device performs ignition control of the plurality of squibs of the ignition device, the plurality of squibs can be selectively ignited by supplying a current whose frequency is changed from the control device. Therefore, the wiring between the control device and the ignition device is not necessary for each of the plurality of squibs, and can be configured with only one set for the parallel circuit, and the number of wirings can be greatly reduced. As a result, the weight and cost of wiring can be reduced, and the space for wiring and man-hours for mounting can also be reduced.

  The current having the same frequency as the resonance frequency may be a current consisting of only that frequency, or may be a current consisting of a plurality of frequency components to which frequencies other than that frequency are added. Therefore, when it is desired to ignite two or more squibs, a current consisting of a frequency component obtained by adding the same frequency as a plurality of resonance frequencies corresponding to each squib may be supplied.

  In the above ignition device of the present invention, the resonance frequency circuit is preferably a circuit in which a coil and a capacitor are connected in parallel.

  In this ignition device, when a predetermined coil and a predetermined capacitor are combined and connected in parallel, a specific resonance frequency is obtained. Therefore, a resonance frequency circuit can be constructed with a very simple configuration.

An ignition device according to the present invention includes a plurality of squibs connected in parallel and a plurality of switching elements each connected to the plurality of squibs and having different bias voltages for each squib, and ignites an arbitrary squib among the plurality of squibs. In this case, a voltage higher than the bias voltage of the switching element connected to the arbitrary squib is applied to a parallel circuit including a plurality of squibs and switching elements connected in parallel .

  In this ignition device, a plurality of squibs are connected in parallel, and a switching element is connected to each squib. Each switching element has a different bias voltage for each squib. When a voltage higher than the bias voltage is applied, the switching element is turned on and a current flows. When a voltage lower than the bias voltage is applied, the switching element is turned off and the current is Not flowing. Therefore, in order to ignite an arbitrary squib, a voltage higher than the bias voltage of the switching element connected to the squib must be applied. That is, a specific squib can be ignited by applying a voltage higher than a bias voltage in a circuit in which the squibs are connected in parallel. Incidentally, when the supplied voltage is equal to or higher than the bias voltage of two or more switching elements, all the squibs connected to the two or more switching elements are ignited. Therefore, when controlling a plurality of squibs of the ignition device by the control device, the plurality of squibs can be selectively ignited by applying a voltage whose voltage value is changed from the control device. Therefore, the wiring between the control device and the ignition device is not necessary for each of the plurality of squibs, and the number of wirings can be greatly reduced.

  The switching elements include diodes, transistors, FETs (Field Effect Transistors), and the like. In the case of a transistor or FET, wiring for driving power is also required.

The ignition device according to the present invention includes a plurality of squibs each having a different resistance value and connected in parallel. When igniting an arbitrary squib among the plurality of squibs, the ignition device ignites according to the resistance value of the arbitrary squib. The voltage required for the above is applied to a parallel circuit composed of a plurality of squibs connected in parallel .

  In this ignition device, a plurality of squibs are connected in parallel. Each squib has a different resistance value, and a predetermined amount of heat is required to ignite. Since each squib has a different resistance value, when a predetermined voltage is applied to the parallel circuit, the calorific value (= [square of applied voltage / each resistance value]) differs for each squib. Therefore, in order to ignite an arbitrary squib, a voltage corresponding to the resistance value of the squib must be applied. That is, a specific squib can be ignited by applying a voltage to a circuit in which the squibs are connected in parallel. Incidentally, when the amount of heat that can be ignited by two or more squibs is generated by the supplied voltage, the two or more squibs are all ignited. Therefore, when controlling a plurality of squibs of the ignition device by the control device, the plurality of squibs can be selectively ignited by applying a voltage whose voltage value is changed from the control device. Therefore, the wiring between the control device and the ignition device is not necessary for each of the plurality of squibs, and the number of wirings can be greatly reduced. In addition, since this ignition circuit does not require an element other than the squib to selectively ignite the squib, the configuration can be greatly simplified.

  According to the present invention, the number of wirings corresponding to the number of squibs is not required, and the number of wirings can be greatly reduced.

  Hereinafter, an embodiment of an ignition device according to the present invention will be described with reference to the drawings.

  In the present embodiment, the ignition device according to the present invention is applied to an ignition circuit of an inflator device of an airbag device in which the back internal pressure is variable. The inflator device according to the present embodiment includes a plurality of inflators corresponding to the stage of changing the back internal pressure. In the ignition circuit according to the present invention, squibs are connected in parallel corresponding to each inflator. This embodiment has five forms. In the first embodiment, resonance frequency circuits are connected to four squibs, respectively. In the second embodiment, resonance frequency circuits are connected to two squibs, respectively. In the third embodiment, diodes are connected to the four squibs, respectively, in the fourth embodiment, FETs are connected to the four squibs, and in the fifth embodiment, the resistance values of the four squibs are different.

  Before describing the ignition circuit according to each embodiment, the airbag apparatus and the inflator apparatus according to the present embodiment will be described. The air bag device includes a bag that can change the internal pressure (and consequently the back capacity) according to the degree (severity) of the collision, and includes an inflator device that can supply gas to the bag in a plurality of stages. . The inflator device is a multi-stage inflator composed of a plurality (four or two) of inflators, and includes an ignition circuit having a squib corresponding to each of the plurality of inflators. Moreover, the airbag apparatus includes a collision detection sensor 1 and an ECU 2 (see FIG. 1 and the like). The collision detection sensor 1 is a sensor that detects the degree (severity) of a vehicle collision, for example, a sensor that detects the acceleration of the vehicle. The ECU 2 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and functions as a control device for the airbag apparatus. The ECU 2 determines the stage of the back internal pressure based on the collision signal SS, and selects an inflator (that is, a squib to be ignited) that generates gas according to the determined stage.

  An ignition circuit 10 according to the first embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram of an ignition circuit according to the first embodiment.

  The ignition circuit 10 includes a first squib 11, a second squib 12, a third squib 13, and a fourth squib 14 corresponding to the four inflators, and the four squibs 11 to 14 are connected in parallel. Further, in the ignition circuit 10, the first resonance frequency circuit 15 is provided at one end of the first squib 11, the second resonance frequency circuit 16 is provided at one end of the second squib 12, and the third resonance frequency circuit 17 is provided at one end of the third squib 13. However, the fourth resonance frequency circuit 18 is connected in series to one end of the fourth squib 14. And in the ignition circuit 10, all the one ends of the 1st-4th resonance frequency circuits 15-18 are connected, and all the other ends of the 1st-4th squib 11-14 are connected, and a parallel circuit is comprised. A current is supplied to each of the squibs 11 to 14 when the resonance frequency circuits 15 to 18 to be connected flow current. In the ignition circuit 10, when a predetermined amount of current flows through the squibs 11 to 14, only the squib through which the current flows ignites.

  Each of the resonance frequency circuits 15 to 18 includes coils 15a, 16a, 17a, and 18a and capacitors 15b, 16b, 17b, and 18b. The coils 15a, 16a, 17a, and 18a and the capacitors 15b, 16b, 17b, and 18b are provided. Connected in parallel. The resonance frequency circuits 15 to 18 are set with resonance frequencies (for example, 100 Hz, 200 Hz, 300 Hz, and 400 Hz) corresponding to the squibs 11 to 14, respectively, and capacitors and coils that have the set resonance frequencies. A combination is selected. That is, the resonance frequency circuits 15 to 18 have different combinations of capacitors and coils, and have different resonance frequencies. In each of the resonance frequency circuits 15 to 18, when a current having a frequency component including the same frequency as the resonance frequency is supplied, the current flows, and when a current having a frequency component not including the same frequency as the resonance frequency is supplied, Cut off the flow.

  Therefore, in the ignition circuit 10, when a current having the same frequency as the resonance frequency of the first resonance frequency circuit 15 is supplied, a current flows through the first squib 11, and a current having the same frequency as the resonance frequency of the second resonance frequency circuit 16 is generated. When supplied, a current flows through the second squib 12. When a current having the same frequency as the resonance frequency of the third resonance frequency circuit 17 is supplied, a current flows through the third squib 13 and the resonance frequency of the fourth resonance frequency circuit 18. Is supplied to the fourth squib 14. Further, in the ignition circuit 10, a current having a frequency component (frequency component obtained by adding a plurality of frequencies) including all the same frequencies as the resonance frequencies of the plurality of resonance frequency circuits among the four resonance frequency circuits 15 to 18 is generated. When supplied, current flows through all the squibs connected to the plurality of resonant frequency circuits. Therefore, the four squibs 11 to 14 can be selectively ignited by supplying a current whose frequency component is changed to the ignition circuit 10.

  In the first embodiment, the ECU 2 can supply a current whose frequency component is changed. When the ECU 2 determines the squib to be ignited based on the collision signal SS, when the determined squib is one, the ECU 2 supplies the ignition circuit 10 with a current having the same frequency as the resonance frequency associated with the squib. When there are a plurality of squibs, a current having a frequency component obtained by adding all the same frequencies as the resonance frequencies respectively associated with the plurality of squibs is supplied to the ignition circuit 10.

  Since it is sufficient that a current having a predetermined frequency component can be supplied from the ECU 2 to the ignition circuit 10, one wiring 3a, 3b is provided between the ECU 2 and the ignition circuit 10 at both ends of the parallel circuit of the ignition circuit 10, respectively. The

  The operation in the ignition circuit 10 will be described. Here, a case where only the first squib 11 is ignited and a case where all the squibs 11 to 14 are ignited will be described.

  A case where only the first squib 11 is ignited will be described. When the ECU 2 determines that only the first squib 11 is ignited based on the collision signal SS, the ECU 2 supplies a current having the same frequency (for example, 100 Hz) as the resonance frequency of the first resonance frequency circuit 15 to the ignition circuit 10. Then, in the ignition circuit 10, since current flows only in the first resonance frequency circuit 15, current flows in the first squib 11, and the first squib 11 is ignited. When the first squib 11 is ignited, gas is generated only by the corresponding first inflator. In this case, since the back is inflated by one inflator, the internal pressure of the back is minimized.

  A case where all the squibs 11 to 14 are ignited will be described. In the ECU 2, when it is determined that all the squibs 11 to 14 are ignited based on the collision signal SS, a frequency component (for example, a frequency component of 100 Hz + 200 Hz + 300 Hz + 400 Hz) obtained by adding the same frequencies as all the resonance frequencies of the resonance frequency circuits 15 to 18. Is supplied to the ignition circuit 10. Then, in the ignition circuit 10, since current flows in all the resonance frequency circuits 15 to 18, current flows in all the squibs 11 to 14, and all the squibs 11 to 14 are ignited. When the squibs 11 to 14 are ignited, gas is generated by four inflators. In this case, since the back is expanded by the four inflators, the internal pressure of the back is maximized.

  According to the ignition circuit 10, it is only necessary to supply a current whose frequency component is changed in order to ignite the four squibs 11 to 14. Therefore, a set of wirings for supplying the current to the ECU 2. Just do it. Therefore, the weight and cost of wiring can be reduced, the wiring space can be saved, and the man-hours for wiring can be reduced.

  With reference to FIG.2 and FIG.3, the ignition circuit 20 which concerns on 2nd Embodiment is demonstrated. FIG. 2 is a circuit diagram of an ignition circuit according to the second embodiment. 3 is a waveform of current supplied to the ignition circuit of FIG. 2, (a) is a current waveform for igniting the first squib, and (b) is a current waveform for igniting the second squib. (C) is a current waveform for igniting the first squib and the second squib.

  The ignition circuit 20 includes a first squib 21 and a second squib 12 corresponding to two inflators, and the two squibs 21 and 22 are connected in parallel. Further, in the ignition circuit 20, a coil 25 is connected in series to one end of the first squib 21, and a capacitor 26 is connected in series to one end of the second squib 22. In the ignition circuit 20, one end of the coil 25 and one end of the capacitor 26 are connected, and the other end of the first squib 21 and the other end of the second squib 22 are connected to form a parallel circuit. A current is supplied to the first squib 21 when the coil 25 passes a current. On the other hand, current is supplied to the squib 22 when the capacitor 26 passes current. In the ignition circuit 20, when a predetermined amount of current flows through the squibs 21, 22, only the squib through which the current flows ignites.

  The coil 25 passes a direct current and does not pass an alternating current. The coil 25 can be regarded as a resonance frequency circuit when there is no capacitor, and the resonance frequency is 0 Hz. On the other hand, the capacitor 26 passes an alternating current and does not flow a direct current. The capacitor 26 can be regarded as a resonance frequency circuit when there is no coil, and the resonance frequency is a frequency determined only by the capacitor 26. Therefore, in the ignition circuit 20, when a direct current is supplied, a current flows through the first squib 21 (see FIG. 3A), and when a current having the same frequency as the resonance frequency determined by the capacitor 26 is supplied, the second squib A current flows through 22 (see FIG. 3B). Further, in the ignition circuit 20, when a current obtained by adding the direct current and a current having the same frequency as the resonance frequency determined by the capacitor 26 is supplied, a current flows through the first squib 21 and the second squib 22 (FIG. 3). (See (c)).

  In the second embodiment, the ECU 2 is the same ECU as in the first embodiment, and the number of squibs to be controlled and the frequency component of the supplied current are different. Further, the wiring between the ECU 2 and the ignition circuit 20 is the same as that in the first embodiment.

  The operation in the ignition circuit 20 will be described. Here, a case where only the first squib 21 is ignited, a case where only the second squib 22 is ignited, and a case where all the squibs 21 and 22 are ignited will be described.

  A case where only the first squib 21 is ignited will be described. When it is determined that only the first squib 11 is ignited based on the collision signal SS, the ECU 2 supplies a direct current to the ignition circuit 20 (see FIG. 3A). Then, in the ignition circuit 20, the coil 25 passes a current, but the capacitor 26 cuts off the current flow, so that a current flows only in the first squib 21, and the first squib 21 ignites. When the first squib 21 is ignited, gas is generated by the first inflator, and the internal pressure of the back by only the first inflator is obtained.

  A case where only the second squib 22 is ignited will be described. When the ECU 2 determines that only the second squib 21 is ignited based on the collision signal SS, the ECU 2 supplies a current having the same frequency as the resonance frequency of the capacitor 26 to the ignition circuit 20 (see FIG. 3B). Then, in the ignition circuit 20, the capacitor 26 passes a current, but the coil 25 interrupts the flow of current, so that a current flows only through the second squib 22, and the second squib 22 ignites. When the second squib 22 is ignited, gas is generated by the second inflator, and the internal pressure of the back is generated only by the second inflator.

  A case where all the squibs 21 and 22 are ignited will be described. When the ECU 2 determines that the first squib 22 and the second squib 21 are to be ignited based on the collision signal SS, the ECU 2 supplies a current obtained by adding a direct current to a current having the same frequency as the resonance frequency of the capacitor 26 to the ignition circuit 20. (See FIG. 3C). Then, in the ignition circuit 20, since the coil 25 and the capacitor 26 pass current, current flows through the first squib 21 and the second squib 22, and the first squib 21 and the second squib 22 are ignited. When the squibs 21 and 22 are ignited, gas is generated by the two inflators, and the internal pressure of the back becomes maximum.

  According to the ignition circuit 20, since the resonance frequency circuit has the simplest configuration in addition to the operational effects according to the first embodiment, the number of elements can be reduced.

  An ignition circuit 30 according to the third embodiment will be described with reference to FIG. FIG. 4 is a circuit diagram of an ignition circuit according to the third embodiment.

  In the ignition circuit 30, the 1st-4th squibs 31-34 are connected in parallel corresponding to four inflators similarly to 1st Embodiment. Furthermore, in the ignition circuit 30, the cathode of the first diode 35 is at one end of the first squib 31, the cathode of the second diode 36 is at one end of the second squib 32, and the cathode of the third diode 37 is at one end of the third squib 33. However, the cathode of the fourth diode 38 is connected to one end of the fourth squib 34. And in the ignition circuit 30, all the anodes of the 1st-4th diodes 35-38 are connected, and all the other ends of the 1st-4th squibs 31-34 are connected, and a parallel circuit is comprised. Each squib 31 to 34 is supplied with a current when a current flows from the anode to the cathode of the diodes 35 to 38 connected thereto (forward direction).

  Each diode 35-38 has a different bias voltage corresponding to each squib 31-34. The first diode 35 has the lowest bias voltage, and the bias voltage increases in order from the first diode 35 (for example, 1V, 2V, 3V, 4V). The bias voltage is a voltage necessary for a current to flow in the forward direction of the diode. Therefore, in each of the diodes 35 to 38, a current flows in the forward direction when a voltage higher than the bias voltage is applied between the terminals, and the current flow is interrupted when a voltage lower than the bias voltage is applied.

  Accordingly, in the ignition circuit 30, when a voltage not lower than the bias voltage of the first diode 35 and lower than the bias voltage of the second diode 36 is applied, a current flows through the first squib 31, and a current higher than the bias voltage of the second diode 36 and the When a voltage lower than the bias voltage of the three diodes 37 is applied, a current flows through the first squib 31 and the second squib 32, and a voltage higher than the bias voltage of the third diode 37 and lower than the bias voltage of the fourth diode 38 is applied. Then, a current flows through the first to third squibs 31 to 33, and when a voltage equal to or higher than the bias voltage of the fourth diode 38 is applied, a current flows through the first to fourth squibs 31 to 34. That is, by applying a predetermined voltage to the ignition circuit 30, it is possible to selectively ignite a squib connected to a diode having a bias voltage lower than the predetermined voltage.

  In the third embodiment, the ECU 2 can apply an arbitrary voltage. When the ECU 2 determines the squib to be ignited based on the collision signal SS, the ECU 2 applies a bias voltage (or higher voltage) of the diode connected to the determined squib to the ignition circuit 30. In this case, the squib connected to the diode having a bias voltage lower than the bias voltage of the diode connected to the determined squib is also ignited. Further, since it is sufficient that a voltage having a different voltage value can be applied from the ECU 2 to the ignition circuit 30, between the ECU 2 and the ignition circuit 30, both ends of the parallel circuit of the ignition circuit 30 are provided as in the first embodiment. One wiring 3a, 3b is provided respectively.

  The operation in the ignition circuit 30 will be described. Here, a case where only the first squib 31 is ignited and a case where all the squibs 31 to 34 are ignited will be described.

  A case where only the first squib 31 is ignited will be described. When the ECU 2 determines that only the first squib 31 is ignited based on the collision signal SS, the ECU 2 applies the same voltage (for example, 1 V) as the bias voltage of the first diode 35 to the ignition circuit 30. Then, in the ignition circuit 30, current flows in the forward direction only in the first diode 35, current flows in the first squib 31, and the first squib 31 is ignited.

  The case where all the squibs 31-34 are ignited is demonstrated. When the ECU 2 determines that the fourth squib 34 is ignited based on the collision signal SS, the ECU 2 applies the same voltage (for example, 4 V) as the bias voltage of the fourth diode 38 to the ignition circuit 30. Then, in the ignition circuit 30, current flows in the forward direction in all the diodes 35 to 38, current flows in all the squibs 31 to 34, and all the squibs 31 to 34 are ignited.

According to the ignition circuit 30, it is only necessary to apply a voltage whose voltage value is changed in order to ignite the four squibs 31 to 34, and therefore, a set of wirings for the wiring between the ECU 2 and the voltage to be applied. Just do it. In the ignition circuit 30, the number of squibs to be ignited can be adjusted by changing the applied voltage. An ignition circuit 40 according to a fourth embodiment will be described with reference to FIG. FIG. 5 is a circuit diagram of an ignition circuit according to the fourth embodiment.

  In the ignition circuit 40, the 1st-4th squibs 41-44 are connected in parallel corresponding to four inflators similarly to 1st Embodiment. Further, in the ignition circuit 40, the source of the first FET 45 at one end of the first squib 41, the source of the second FET 46 at one end of the second squib 42, the source of the third FET 47 at one end of the third squib 43, and the fourth squib 44. Is connected to the source of the fourth FET 48. In the ignition circuit 40, the gates of the first to fourth FETs 45 to 48 are all connected, and the other ends of the first to fourth squibs 41 to 44 are all connected to constitute a parallel circuit. The squibs 41 to 44 are supplied with current when the connected FETs 45 to 48 are turned on and a current flows between the drain and the source.

  Each FET 45-48 has a different bias voltage corresponding to each squib 41-44. As for the bias voltage, the bias voltage of the first FET 45 is the lowest, and the bias voltage becomes higher in order from the first FET 45 (for example, 1V, 2V, 3V, 4V). The bias voltage is a voltage necessary for turning on the FET. When a voltage higher than the bias voltage is applied to the gate of the FET, the FET is turned on and a current flows between the drain and the source. When applied, the FET is turned off and no current flows between the drain and source. In order to pass a current between the drain and the source, all the drains of the FETs 45 to 48 are connected, and a drive voltage is applied from the ECU 2.

  Therefore, in the ignition circuit 40, when a voltage not lower than the bias voltage of the first FET 45 and lower than the bias voltage of the second FET 46 is applied, a current flows through the first squib 41, and is higher than the bias voltage of the second FET 46 and lower than the bias voltage of the third FET 47. When a voltage is applied, a current flows through the first squib 41 and the second squib 42, and when a voltage higher than the bias voltage of the third FET 47 and lower than the bias voltage of the fourth FET 48 is applied, the first to third squibs 41 to 43 are applied. When a current flows and a voltage higher than the bias voltage of the fourth FET 48 is applied, a current flows through the first to fourth squibs 41 to 44. That is, by applying a predetermined voltage to the ignition circuit 40, a squib connected to an FET having a bias voltage lower than the predetermined voltage can be selectively ignited.

  The ECU 2 of the fourth embodiment is the same ECU as that of the third embodiment. Further, since it is sufficient that voltages with different voltage values can be applied from the ECU 2 to the ignition circuit 40, one wiring 3a, 3b is provided between the ECU 2 and the ignition circuit 40 at both ends of the parallel circuit of the ignition circuit 40, respectively. Further, a wiring 3c connected to the drain of the FET is also provided in order to apply the driving voltage of the FET.

  The operation in the ignition circuit 40 will be described. Here, a case where only the first squib 41 is ignited and a case where all the squibs 41 to 44 are ignited will be described.

  A case where only the first squib 41 is ignited will be described. When the ECU 2 determines that only the first squib 41 is ignited based on the collision signal SS, the ECU 2 applies the same voltage (for example, 1 V) as the bias voltage of the first FET 45 to the ignition circuit 40. Then, in the ignition circuit 40, only the first FET 45 is turned on, a current flows between the drain and the source, a current flows through the first squib 41, and the first squib 41 is ignited.

  A case where all the squibs 41 to 44 are ignited will be described. When the ECU 2 determines that the fourth squib 44 is ignited based on the collision signal SS, the ECU 2 applies the same voltage (for example, 4 V) as the bias voltage of the fourth FET 48 to the ignition circuit 40. Then, in the ignition circuit 40, all the FETs 45 to 48 are turned on, current flows between the drain and source, current flows through all the squibs 41 to 44, and all the squibs 41 to 44 are ignited.

  The ignition circuit 40 has the same effects as the ignition circuit 30 according to the third embodiment. In the case of the ignition circuit 40, a separate wiring for driving power of the FET is required.

  With reference to FIG. 6, the ignition circuit 50 which concerns on 5th Embodiment is demonstrated. FIG. 6 is a circuit diagram of an ignition circuit according to the fifth embodiment.

  In the ignition circuit 50, the 1st-4th squibs 51-54 are connected in parallel corresponding to four inflators similarly to 1st Embodiment. Each squib 51-54 has a different resistance value. As for the resistance value, the resistance value of the first squib 51 is the lowest, and the resistance value increases in order from the first squib 51. Since the first to fourth squibs 51 to 54 are connected in parallel, the same voltage is applied to both ends when a voltage is applied from the ECU 2. Therefore, the amount of heat generated in each of the squibs 51 to 54 is different (square of applied voltage / each resistance value), and the amount of heat of the first squib 51 is the largest. Further, the first to fourth squibs 51 to 54 ignite when they exceed a predetermined amount of heat. This predetermined amount of heat is the same amount of heat in the first to fourth squibs 51 to 54. Therefore, the ignition circuit 50 ignites in the order of the first to fourth squibs 51 to 54 as the applied voltage increases.

  Therefore, in the ignition circuit 50, when a voltage not lower than the voltage at which the first squib 51 can be ignited and lower than the voltage at which the second squib 52 can be ignited, current flows through the first squib 51, and the second squib 52 is ignited. When a voltage that is greater than the possible voltage and less than the voltage that the third squib 53 can ignite is applied, current flows through the first squib 51 and the second squib 52, and the third squib 53 is greater than the impressable voltage that can be ignited and the fourth squib 53. When a voltage lower than the voltage that can be ignited by the squib 54 is applied, a current flows through the first to third squibs 51 to 53, and when a voltage equal to or higher than the voltage that can be ignited by the fourth squib 54 is applied. A current flows through the fourth squibs 51 to 54. That is, by applying a predetermined voltage to the ignition circuit 50, it is possible to selectively ignite a squib that generates an amount of heat that can be ignited by the predetermined voltage.

  The ECU 2 of the fifth embodiment is the same ECU as that of the third embodiment. In addition, since it is sufficient that voltages with different voltage values can be applied from the ECU 2 to the ignition circuit 50, the wiring between the ECU 2 and the ignition circuit 50 is the same as that in the third embodiment.

  The operation in the ignition circuit 50 will be described. Here, a case where only the first squib 51 is ignited and a case where all the squibs 51 to 54 are ignited will be described.

  A case where only the first squib 51 is ignited will be described. When the ECU 2 determines that only the first squib 51 is ignited based on the collision signal SS, the ECU 2 applies a voltage that can generate an amount of heat that can be ignited only by the first squib 51 to the ignition circuit 50. Then, in the ignition circuit 50, only the first squib 51 exceeds the amount of heat that can be ignited, and the first squib 51 is ignited.

  The case where all the squibs 51-54 are ignited is demonstrated. When it is determined that the ECU 2 ignites up to the fourth squib 54 based on the collision signal SS, the ECU 2 applies a voltage that can generate an amount of heat that can be ignited up to the fourth squib 54 to the ignition circuit 50. Then, in the ignition circuit 50, all the squibs 51 to 54 exceed the amount of heat that can be ignited, and all the squibs 51 to 54 are ignited.

  According to the ignition circuit 50, the same effect as that of the third embodiment is obtained, and since no switching element such as a diode is required, the number of parts can be reduced and the configuration can be greatly simplified.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, although applied to the airbag apparatus in the present embodiment, the present invention can also be applied to other apparatuses (for example, pretensioners) including an ignition apparatus in which a plurality of squibs are connected in parallel. In the present embodiment, the present invention is applied to an airbag apparatus that changes the internal pressure of the bag, but the present invention can also be applied to an airbag apparatus that includes a plurality of bags such as a main bag and a sub bag.

  Further, although the present embodiment is applied to the case where four or two squibs are connected in parallel, the number of squibs is not particularly limited.

  Further, in the present embodiment, it is configured to determine which squib is ignited (that is, which inflator generates gas) based on the degree of collision by the collision detection sensor. It may be determined which squib is ignited based on the above.

  In this embodiment, the diode and the FET are applied as the switching elements. However, other switching elements such as transistors are also applicable.

It is a circuit diagram of the ignition circuit which concerns on 1st Embodiment. It is a circuit diagram of the ignition circuit which concerns on 2nd Embodiment. 3 is a waveform of a current supplied to the ignition circuit of FIG. 2, (a) is a current waveform for igniting the first squib, (b) is a current waveform for igniting the second squib, and (c ) Is a current waveform for igniting the first squib and the second squib. It is a circuit diagram of the ignition circuit which concerns on 3rd Embodiment. It is a circuit diagram of the ignition circuit which concerns on 4th Embodiment. It is a circuit diagram of the ignition circuit which concerns on 5th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Collision detection sensor, 2 ... ECU, 3a, 3b, 3c ... Wiring 10, 20, 30, 40, 50 ... Ignition circuit 11, 21, 21, 31, 41, 51 ... 1st squib, 12, 22, 32 , 42, 52 ... second squib, 13, 33, 43, 53 ... third squib, 14, 34, 44, 54 ... fourth squib, 15 ... first resonance frequency circuit, 16 ... second resonance frequency circuit, 17 ... 3rd resonance frequency circuit, 18 ... 4th resonance frequency circuit, 15a-18a, 25 ... Coil, 15b-18b, 26 ... Capacitor, 35 ... 1st diode, 36 ... 2nd diode, 37 ... 3rd diode, 38 ... 4th diode, 45 ... 1st FET, 46 ... 2nd FET, 47 ... 3rd FET, 48 ... 4th FET

Claims (4)

Multiple squibs connected in parallel;
A plurality of resonant frequency circuits each connected to the plurality of squibs and having a different resonant frequency for each squib ,
When an arbitrary squib is ignited among the plurality of squibs, a current having the same frequency as the resonance frequency of the resonance frequency circuit connected to the arbitrary squib is paralleled with the plurality of squibs connected in parallel and the resonance frequency circuit. An ignition device characterized by being supplied to a circuit .   The ignition device according to claim 1, wherein the resonance frequency circuit is a circuit in which a coil and a capacitor are connected in parallel. Multiple squibs connected in parallel;
A plurality of switching elements each connected to the plurality of squibs and having a different bias voltage for each squib,
When igniting an arbitrary squib among the plurality of squibs, a voltage higher than a bias voltage of a switching element connected to the arbitrary squib is applied to the parallel circuit including the plurality of squibs and the switching elements connected in parallel. An ignition device characterized by. A plurality of squibs each having a different resistance value and connected in parallel,
When igniting an arbitrary squib among the plurality of squibs, a voltage required for ignition is applied to a parallel circuit composed of the plurality of squibs connected in parallel according to the resistance value of the arbitrary squib. Ignition device to do.

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