JP2017206199A - Squib control device and squib control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely start up an occupant protection device.SOLUTION: A squib control device 10 includes a differential amplifier 17 and a processor 18. The processor 18 includes an ignition determination section 101 and a supply control section 102, as functions of the processor 18. The differential amplifier 17 outputs a voltage difference ΔV between a voltage in a terminal TAH and a voltage in a terminal TAL to the processor 18. The ignition determination section 101 determines whether or not a squib 3 is ignited, on the basis of the voltage difference ΔV inputted from the differential amplifier 17, and outputs a determination result in the ignition determination section 101 to the supply control section 102. The supply control section 102 controls an OFF signal outputted from the supply control section 102 to transistors 14 and 15, on the basis of the determination result in the ignition determination section 101, namely whether the squib 3 has been ignited or not.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a squib control device and a squib control method.

  As an apparatus for protecting an occupant when a collision of a vehicle such as a vehicle is predicted (hereinafter sometimes referred to as an “occupant protection apparatus”), for example, there are an air bag, a seat belt pretensioner, and the like. Activation of the air bag and the seat belt pretensioner is performed by ignition of the squib. When the squib is ignited, the airbag is activated and deployed, or the seat belt pretensioner is activated to forcibly retract the seat belt.

  Various types of energization control for the squib are being studied. For example, a technique for cutting off energization to the squib based on the remaining voltage of the auxiliary battery has been proposed.

Japanese Patent Application Laid-Open No. 11-069663

  Here, if energization to the squib is cut off even though the squib is not ignited, the occupant protection device may not be activated at the time of a vehicle collision.

  The disclosed technology has been made in view of the above, and an object thereof is to reliably start an occupant protection device.

  In the disclosed aspect, the squib control device includes an ignition determination unit and a supply control unit. The ignition determination unit determines whether or not the squib has been ignited. The supply control unit controls supply of current to the squib based on whether or not the squib has ignited.

  According to the disclosed aspect, the occupant protection device can be reliably activated.

FIG. 1 is a diagram illustrating a configuration example of an ECU having the squib control device according to the first embodiment. FIG. 2 is a flowchart for explaining an example of processing of the squib control device according to the first embodiment. FIG. 3 is a diagram illustrating an example of the operation of the squib control device according to the first embodiment. FIG. 4 is a diagram illustrating a configuration example of an ECU having the squib control device according to the second embodiment. FIG. 5 is a flowchart for explaining an example of processing of the squib control device according to the second embodiment. FIG. 6 is a flowchart for explaining an example of processing of the squib control device according to the third embodiment.

  Embodiments of a squib control device and a squib control method disclosed in the present application will be described below with reference to the drawings. In addition, the squib control device and the squib control method disclosed in the present application are not limited by this embodiment. Hereinafter, a vehicle will be described as an example of a vehicle to which the squib control device and the squib control method disclosed in the present application are applied, but the vehicle to which the squib control device and the squib control method disclosed in the present application are applied is limited to the vehicle. Not. Moreover, the same code | symbol is attached | subjected to the structure which has the same function in each Example, and the overlapping description is abbreviate | omitted.

[Example 1]
<Configuration of squib control device>
FIG. 1 is a diagram illustrating a configuration example of an ECU (Engine Control Unit) including the squib control device according to the first embodiment. The ECU 1 shown in FIG. 1 is, for example, an airbag ECU that controls activation of an airbag, a pretensioner ECU that controls activation of a seat belt pretensioner, and the like, and is mounted on a vehicle. However, the ECU 1 is not limited to the airbag ECU and the pretensioner ECU. The ECU 1 may be an ECU having the squib control device 10.

  In FIG. 1, the ECU 1 includes a squib control device 10, a backup capacitor 11, a backflow prevention diode 12, constant current circuits 13 and 16, and transistors 14 and 15.

  The backup capacitor 11 is charged by the main battery 2 in normal times. Further, in normal times, the main battery 2 supplies current to the squib 3 connected to the ECU 1. The backup capacitor 11 functions as an “auxiliary battery” that is a power source for activating the occupant protection device even when the power supply line from the main battery 2 to the ECU 1 is disconnected due to an impact at the time of a vehicle collision. Therefore, when the power supply line from the main battery 2 to the ECU 1 is disconnected, a current is supplied from the backup capacitor 11 to the squib 3 connected to the ECU 1. That is, current is supplied to the squib 3 from the main battery 2 or the backup capacitor 11 as an auxiliary battery.

  The backflow prevention diode 12 prevents the current supplied from the main battery 2 or the backup capacitor 11 from flowing back to the main battery 2 side and the backup capacitor 11 side.

  The constant current circuits 13 and 16 are formed by, for example, a transistor circuit, and make the current flowing through the transistors 14 and 15 constant. Therefore, a constant current I1 is supplied to the squib 3 while the transistors 14 and 15 are ON. The value of the constant current I1 is, for example, 1.2 [A].

  One end of the transistor 14 is connected to the constant current circuit 13, and the other end of the transistor 14 is connected to the squib 3 via one terminal TAH of the squib 3 (that is, the input end of the squib 3). One end of the transistor 15 is connected to the squib 3 via the other terminal TAL of the squib 3 (that is, the output end of the squib 3), and the other end of the transistor 15 is connected to the constant current circuit 16. The transistors 14 and 15 function as “switches” whose ON / OFF is controlled by a control signal output from the squib control device 10. Hereinafter, a control signal for turning the transistors 14 and 15 from OFF to ON may be referred to as an “ON signal”, and a control signal for turning the transistors 14 and 15 from ON to OFF may be referred to as an “OFF signal”.

  The squib control device 10 includes a differential amplifier 17, a processor 18, and a memory 19. Examples of the processor 18 include a central processing unit (CPU), a digital signal processor (DSP), and a field programmable gate array (FPGA). Examples of the memory 19 include RAM such as SDRAM, ROM, flash memory, and the like.

  Two input terminals of the differential amplifier 17 are connected to the terminal TAH and the terminal TAL. The differential amplifier 17 has a voltage difference between a voltage at the terminal TAH (hereinafter sometimes referred to as “terminal voltage VH”) and a voltage at the terminal TAL (hereinafter sometimes referred to as “terminal voltage VL”). ΔV (hereinafter also referred to as “terminal voltage difference ΔV”) is output to the processor 18.

  The memory 19 stores a threshold value V1 and the like for the inter-terminal voltage difference ΔV.

  The processor 18 includes an ignition determination unit 101, a supply control unit 102, and a timer 103 as functions of the processor 18.

  The ignition determination unit 101 determines whether or not the squib 3 has ignited based on the inter-terminal voltage difference ΔV input from the differential amplifier 17, and outputs the determination result in the ignition determination unit 101 to the supply control unit 102. To do. Details of the ignition determination unit 101 will be described later.

  Supply control unit 102 controls an ON signal output from supply control unit 102 to transistors 14 and 15 based on an ignition determination value input from the outside of ECU 1. Further, the supply control unit 102 controls the OFF signal output from the supply control unit 102 to the transistors 14 and 15 based on the determination result of the ignition determination unit 101, that is, whether or not the squib 3 has been ignited.

  Here, before the supply of current to the squib 3 is started, the supply of current to the squib 3 is stopped while the transistors 14 and 15 are OFF. Supply of current to the squib 3 is started when the transistors 14 and 15 are turned from OFF to ON, and supply of current to the squib 3 is continued when the transistors 14 and 15 are turned ON. Also, the supply of current to the squib 3 is stopped when the transistors 14 and 15 are turned from ON to OFF. Therefore, current is supplied to the squib 3 from when the ON signal is output from the supply control unit 102 to the transistors 14 and 15 until the OFF signal is output. That is, the supply control unit 102 controls the supply of current to the squib 3 based on whether or not the squib 3 is ignited. Details of the supply control unit 102 will be described later.

  The timer 103 is a predetermined time from the time when the transistors 14 and 15 are turned on to the time when the transistors 14 and 15 are turned on from the time when the transistors 14 and 15 are turned on. In the following, this may be referred to as “current supply duration”) is set as the expiration time EXT of the timer 103, and the current supply duration is managed.

<Processing of squib control device>
FIG. 2 is a flowchart for explaining an example of processing of the squib control device according to the first embodiment. The flowchart shown in FIG. 2 is started at regular intervals. Further, as an initial state, the transistors 14 and 15 are OFF, and no current is supplied to the squib 3.

  First, the supply control unit 102 determines whether or not the vehicle collides based on the input ignition determination value (step ST11). As an example of the ignition determination value, an integral value of acceleration detected by a G sensor (not shown) mounted on the vehicle is raised. For example, when the ignition determination value is an integral value of acceleration, the supply control unit 102 determines that the vehicle collides (that is, a vehicle collision is predicted) when the integral value of acceleration is equal to or greater than the threshold value A1. . On the other hand, when the integral value of acceleration is less than the threshold value A1, the supply control unit 102 determines that the vehicle does not collide (that is, no vehicle collision is predicted). When it is determined that the vehicle does not collide (step ST11: No), the process of the flowchart shown in FIG. 2 ends.

  On the other hand, when it is determined that the vehicle collides (step ST11: Yes), the supply control unit 102 reads the predetermined current supply duration T1 stored in the memory 19 from the memory 19 and continues the read current supply. Time T1 is set in timer 103 as expiration time EXT (step ST13). The value of the predetermined current supply duration time T1 is, for example, 2 [ms].

  Next, the supply control unit 102 starts the timer 103 with the expiration time EXT set (step ST15), and outputs an ON signal to the transistors 14 and 15 to switch the transistors 14 and 15 from OFF to ON (step ST17). ). When the transistors 14 and 15 are turned from OFF to ON, supply of current to the squib 3 is started (that is, energization to the squib 3 is started).

  Next, the ignition determination unit 101 and the supply control unit 102 refer to the timer 103, and the measurement time in the timer 103 (that is, the elapsed time from when the transistors 14 and 15 are turned on) has reached the expiration time EXT. (Step ST19).

  If the time measured by the timer 103 has not reached the expiration time EXT (step ST19: Yes), the ignition determination unit 101 reads the threshold value V1 stored in the memory 19 from the memory 19 and inputs it from the differential amplifier 17. It is determined whether or not the inter-terminal voltage difference ΔV exceeds the threshold value V1 (step ST21). For example, the threshold value V1 is ideally 0 [V]. The ignition determination unit 101 outputs a determination result indicating whether or not the terminal voltage difference ΔV is greater than the threshold value V1 to the supply control unit 102.

  If the inter-terminal voltage difference ΔV is less than or equal to the threshold value V1 (step ST21: No), the process returns to step ST19.

  Here, from the time when the transistors 14 and 15 are turned on (that is, when the supply of current to the squib 3 is started) to the time when the squib 3 is ignited, the power from the main battery 2 or the backup capacitor 11 is supplied. A voltage (for example, 12 [V]) is observed as the terminal voltage VH and the terminal voltage VL. On the other hand, when the squib 3 is ignited by supplying current to the squib 3, the squib 3 is disconnected and opened, so that the power supply voltage from the main battery 2 or the backup capacitor 11 is observed as the terminal voltage VH. Thus, 0 [V] which is the voltage of GND is observed as the terminal voltage VL. That is, there is no difference between the terminal voltage VH and the terminal voltage VL while the squib 3 is not ignited after the supply of current to the squib 3 is started. On the other hand, when the squib 3 is ignited after the supply of current to the squib 3 is started, a difference occurs between the terminal voltage VH and the terminal voltage VL. Therefore, the ignition determination unit 101 determines whether or not the squib 3 has ignited based on the difference between the terminal voltage VH and the terminal voltage VL, that is, the inter-terminal voltage difference ΔV. That is, the ignition determination unit 101 determines that the squib 3 is not ignited when the inter-terminal voltage difference ΔV is equal to or less than the threshold value V1, while the squib 3 is ignited when the inter-terminal voltage difference ΔV is greater than the threshold value V1. Judge.

  When the measurement time in the timer 103 reaches the expiration time EXT in step ST19 (step ST19: No), or when the inter-terminal voltage difference ΔV exceeds the threshold value V1 (step ST21: Yes), the supply control unit 102 Then, an OFF signal is output to the transistors 14 and 15 to switch the transistors 14 and 15 from ON to OFF (step ST23). When the transistors 14 and 15 are switched from ON to OFF, the supply of current to the squib 3 is stopped. After the process of step ST23, the process of the flowchart shown in FIG.

  That is, according to the flowchart shown in FIG. 2, the supply control unit 102 allows the ignition determination unit 101 to perform the squib 3 even before the current supply time to the squib 3 reaches the current supply duration T1 (Yes in step ST19). Is determined to have ignited (step ST21: Yes), the supply of current to the squib 3 is stopped (step ST23).

  The transistors 14 and 15 are turned on at step ST17 and turned off at step ST23. Therefore, when the ignition determination unit 101 determines that the squib 3 is not ignited (step ST21: No), the transistors 14 and 15 are kept in the ON state. That is, after the energization of the squib 3 is started, if the ignition determination unit 101 determines that the squib 3 is not ignited, the supply control unit 102 continues to supply current to the squib 3.

  Even when the ignition determination unit 101 determines that the squib 3 has not been ignited (step ST21: No), the supply control unit 102 determines that the time measured by the timer 103 has reached the expiration time EXT. That is, when the current supply time to the squib 3 reaches the current supply duration T1 (step ST19: No), the supply of current to the squib 3 is stopped (step ST23).

<Operation of squib control device>
FIG. 3 is a diagram illustrating an example of the operation of the squib control device according to the first embodiment.

  In FIG. 3, supply of the current I1 to the squib 3 is started when the transistors 14 and 15 are turned on from OFF, and the supply of the current I1 to the squib 3 is continued while the transistors 14 and 15 are turned on. Is done. When the transistors 14 and 15 are turned from ON to OFF, the supply of the current I1 to the squib 3 is stopped. The current waveform CW1 indicates a current waveform when the supply of current to the squib 3 is continued until the predetermined current supply duration T1 after the supply of current to the squib 3 is started. The current waveform CW2 shows the current when the supply of current to the squib 3 is stopped when the time T2 elapses before the predetermined current supply duration T1 elapses after the supply of current to the squib 3 starts. Waveform is shown. In FIG. 3, it is assumed that the voltage difference ΔV between the terminals exceeds the threshold value V1 and the ignition determination unit 101 determines that the squib 3 has ignited at the time T2 after the start of supplying the current to the squib 3. .

  Here, the energy supplied to the squib 3 is defined by the product of the supplied current value and the current supply time, that is, the current I1 and the time when the transistors 14 and 15 are ON in FIG. Expressed in area. Therefore, when the current supplied to the squib 3 is constant at I1, the energy supplied to the squib 3 is larger in the case of T1 than in the case where the supply time of the current to the squib 3 is T2.

  However, in general, the predetermined current supply duration T1 is set as a time corresponding to energy for which the ignition of the squib 3 is reliably guaranteed. For this reason, when the squib 3 is ignited, the energy defined by the predetermined current supply duration T1 has a sufficient margin. Therefore, even before the supply time of the current to the squib 3 reaches T1, the energy supplied to the squib 3 may reach a threshold value that induces ignition of the squib 3, and the squib 3 may ignite.

  Therefore, in the first embodiment, as described above, the ignition determination unit 101 determines whether or not the squib 3 has been ignited. Then, the supply control unit 102 determines that the ignition determination unit 101 determines that the squib 3 is ignited (that is, the voltage difference between the terminals) even before T1 elapses from the time when the supply of current to the squib 3 starts. At the time when ΔV exceeds the threshold value V1, the supply of the current I1 to the squib 3 is immediately stopped. It is preferable that the time T2 is designed to be about a half of the time T1 while the current I1 is constant.

  As described above, in the first embodiment, the squib control device 10 includes the ignition determination unit 101 and the supply control unit 102. The ignition determination unit 101 determines whether or not the squib 3 has been ignited. The supply control unit 102 controls the supply of current to the squib 3 based on whether or not the squib 3 is ignited.

  In this way, in order to prevent the supply of current to the squib 3 from being cut off even when the squib 3 is not ignited, an occupant such as an air bag or a seat belt pretensioner that is activated by the ignition of the squib 3 The protection device can be reliably activated. Therefore, the safety of the passenger can be improved.

  In the first embodiment, the supply control unit 102 stops the supply of current to the squib 3 when the ignition determination unit 101 determines that the squib 3 is ignited.

  By doing so, the supply of current to the squib 3 can be cut immediately at the time of ignition of the squib 3 before the elapse of the predetermined current supply continuation time T1 after the supply of current to the squib 3 is started. Consumption of the charging current of the backup capacitor 11 that is an auxiliary battery can be suppressed. In other words, when the squib 3 is ignited, it is sufficient to use the back backup capacitor 11 having a smaller charge capacity than the conventional one. For this reason, the space for installing the backup capacitor 11 in the vehicle can be saved, and the manufacturing cost of the vehicle can be reduced.

  In the first embodiment, the supply control unit 102 continues the supply of current to the squib 3 when the ignition determination unit 101 determines that the squib 3 is not ignited.

  In this way, when the squib 3 is not ignited, the current supply to the squib 3 can be continued until the squib 3 is ignited.

  Further, in the first embodiment, when the ignition determination unit 101 determines that the squib 3 is not ignited, the supply control unit 102 has passed a predetermined current supply continuation time T1 from the start of current supply to the squib 3. At a later time, the supply of current to the squib 3 is stopped.

  In this way, when the squib 3 is not ignited, supply of current to the squib 3 is continued until the current supply duration T1, which is the time corresponding to the energy for which the ignition of the squib 3 is reliably guaranteed, has elapsed. Can continue. For this reason, the supply of current to the squib 3 can be cut after the squib 3 is reliably ignited.

  In the first embodiment, the ignition determination unit 101 determines whether or not the squib 3 has been ignited based on the voltage difference ΔV between the terminals.

  By doing so, it is possible to easily and accurately determine whether or not the squib 3 has been ignited.

[Example 2]
<Configuration of squib control device>
FIG. 4 is a diagram illustrating a configuration example of an ECU having the squib control device according to the second embodiment. In FIG. 4, the processor 18 has a short determination unit 104 as a function of the processor 18.

  The short determination unit 104 determines whether a short circuit has occurred at the terminal TAH (that is, the input terminal of the squib 3) or the terminal TAL (that is, the output terminal of the squib 3). The determination result is output to the supply control unit 102. For example, a short circuit may occur in the terminal TAH or the terminal TAL due to the biting of the wire harness due to an impact at the time of a vehicle collision.

  Here, four types of shorts, that is, a terminal TAH + B short-circuit, a terminal TAH GND short-circuit, a terminal TAL + B short-circuit, and a terminal TAL GND short-circuit are assumed as shorts generated at the terminal TAH and the terminal TAL.

  When the terminal TAH is + B shorted, the terminal TAH side wiring is shorted to the positive electrode of the main battery 2, and when the terminal TAH is GND shorted, the terminal TAH side wiring is shorted to the GND line. Further, when the terminal TAL is + B shorted, the terminal TAL side wiring is shorted to the positive electrode of the main battery 2, and when the terminal TAL is GND shorted, the terminal TAL side wiring is shorted to the GND line.

  In the state where the transistors 14 and 15 are OFF and the terminal TAH and the terminal TAL are not short-circuited, the terminal voltage VH and the terminal voltage VL are maintained at the midpoint voltage. For example, when the power supply voltage of the main battery 2 is 12 [V], the terminal voltage VH and the terminal voltage VL are about 6 [V] of the midpoint voltage in a state where no short circuit occurs in the terminals TAH and TAL. Is maintained.

  On the other hand, when a + B short circuit occurs at the terminal TAH, the terminal voltage VH increases to 12 [V], and when a GND short circuit occurs at the terminal TAH, the terminal voltage VH decreases to 0 [V]. When a + B short circuit occurs at the terminal TAL, the terminal voltage VL increases to 12 [V], and when a GND short circuit occurs at the terminal TAL, the terminal voltage VL decreases to 0 [V].

  Therefore, the short determination unit 104 monitors the terminal voltage VH and the terminal voltage VL. Then, the short determination unit 104 determines that a + B short circuit has occurred in the terminal TAH when the terminal voltage VH is equal to or higher than the threshold value VB, and determines that a GND short circuit has occurred in the terminal TAH when the terminal voltage VH is less than the threshold value VG. To do. The short determination unit 104 determines that a + B short circuit has occurred in the terminal TAL when the terminal voltage VL is equal to or higher than the threshold value VB, and determines that a GND short circuit has occurred in the terminal TAL when the terminal voltage VL is lower than the threshold value VG. To do. When the power supply voltage of the main battery 2 is 12 [V], for example, the threshold value VB may be set to 10 [V] and the threshold value VG may be set to 2 [V]. The threshold values VB and VG are stored in the memory 19 in advance, and the short determination unit 104 reads the threshold values VB and VG from the memory 19 and acquires them.

  Then, in addition to the processing of the first embodiment, the supply control unit 102 controls the supply of current to the squib 3 based on whether or not a short circuit has occurred in the terminal TAH or the terminal TAL.

<Processing of squib control device>
FIG. 5 is a flowchart for explaining an example of processing of the squib control device according to the second embodiment. The flowchart shown in FIG. 5 is obtained by adding the process of step ST31 to the flowchart shown in FIG. 2 of the first embodiment.

  In FIG. 5, when it is determined that the vehicle collides (step ST11: Yes), the short determination unit 104 reads the threshold values VB and VG from the memory 19, and determines whether or not a short circuit has occurred in the terminal TAH or the terminal TAL. Is determined (step ST31).

  When either a + B short circuit or a GND short circuit has occurred at the terminal TAH or the terminal TAL (step ST31: No), the current is not supplied to the squib 3 while the transistors 14 and 15 remain off. The process of the flowchart shown in FIG.

  On the other hand, when neither the + B short circuit nor the GND short circuit has occurred in either the terminal TAH or the terminal TAL (step ST31: Yes), the process proceeds to step ST13.

  That is, according to the flowchart shown in FIG. 5, the supply control unit 102 determines that either the + B short circuit or the GND short circuit has occurred in the terminal TAH or the terminal TAL by the short circuit determination unit 104 (step). ST31: No), the supply of current to the squib 3 is kept stopped.

  As described above, in the second embodiment, the squib control device 10 further includes the short determination unit 104. The short determination unit 104 determines whether a short circuit has occurred in the terminal TAH or the terminal TAL. The supply control unit 102 controls the supply of current to the squib 3 based on whether or not a short circuit has occurred in the terminal TAH or the terminal TAL.

  For example, when the short determining unit 104 determines that the short circuit has occurred in the terminal TAH or the terminal TAL, the supply control unit 102 keeps the supply of current to the squib 3 stopped.

  By doing so, it is possible to prevent the occupant protection device from malfunctioning when a short circuit occurs at the terminal of the squib 3 due to the occurrence of an abnormality such as biting of the wire harness due to an impact at the time of a vehicle collision.

[Example 3]
The third embodiment is the same as the second embodiment in that the supply control unit 102 controls the supply of current to the squib 3 based on whether or not a short circuit has occurred in the terminal TAH or the terminal TAL. However, in the third embodiment, the processing of the supply control unit 102 when a short circuit occurs in the terminal TAH or the terminal TAL is different from the second embodiment.

<Processing of squib control device>
FIG. 6 is a flowchart for explaining an example of processing of the squib control device according to the third embodiment. Here, even when the terminal TAH or the terminal TAL is short-circuited, depending on the short-circuit state, the squib 3 can be energized, and there is a possibility that the occupant protection device operates normally. Therefore, the flowchart shown in FIG. 6 is obtained by adding steps ST41 to ST47 to the flowchart shown in FIG. 5 of the second embodiment.

  In FIG. 6, when it is determined that the vehicle collides (step ST <b> 11: Yes), the short determination unit 104 reads the threshold values VB and VG from the memory 19 and determines whether or not a short circuit has occurred at the terminal TAH or the terminal TAL. Is determined (step ST31).

  If neither + B short circuit nor GND short circuit has occurred in either terminal TAH or terminal TAL (step ST31: Yes), the process proceeds to step ST13.

  On the other hand, when either the + B short circuit or the GND short circuit has occurred in the terminal TAH or the terminal TAL (step ST31: No), the supply control unit 102 stores the predetermined current supply duration time stored in the memory 19 T1 is read from the memory 19, and the read current supply duration T1 is set in the timer 103 as the expiration time EXT (step ST41).

  Next, the supply control unit 102 starts the timer 103 with the expiration time EXT set (step ST43), and outputs an ON signal to the transistors 14 and 15 to switch the transistors 14 and 15 from OFF to ON (step ST45). ). When the transistors 14 and 15 are turned from OFF to ON, supply of current to the squib 3 is started (that is, energization to the squib 3 is started).

  Next, the supply control unit 102 refers to the timer 103 and determines whether or not the measurement time in the timer 103 (that is, the elapsed time from when the transistors 14 and 15 are turned on) has reached the expiration time EXT. (Step ST47).

  If the time measured by the timer 103 has not reached the expiration time EXT (step ST47: No), the process returns to step ST47. That is, the process of step ST47 is repeated until the measurement time in the timer 103 reaches the expiration time EXT.

  If the measurement time in the timer 103 reaches the expiration time EXT in step ST47 (step ST47: Yes), the supply control unit 102 outputs an OFF signal to the transistors 14 and 15 to turn on the transistors 14 and 15 To OFF (step ST23). When the transistors 14 and 15 are switched from ON to OFF, the supply of current to the squib 3 is stopped. After the process of step ST23, the process of the flowchart shown in FIG.

  That is, according to the flowchart shown in FIG. 6, when the supply control unit 102 determines that either the + B short circuit or the GND short circuit has occurred in the terminal TAH or the terminal TAL by the short circuit determination unit 104 (step). (ST31: No), when the measurement time in the timer 103 reaches the expiration time EXT, that is, when the current supply time to the squib 3 reaches the current supply duration T1 (step ST47: Yes), the squib 3 Is stopped (step ST23).

  As described above, in the third embodiment, the supply control unit 102 starts supplying current to the squib 3 when the short determination unit 104 determines that a short circuit has occurred in the terminal TAH or the terminal TAL. The supply of current to the squib 3 is stopped at a time after a predetermined current supply continuation time T1 has elapsed.

  In this way, depending on the short-circuit state, it is possible to energize the squib 3, and when the possibility that the occupant protection device operates normally remains, the energy that ensures the ignition of the squib 3 is ensured. The ignition of the squib 3 can be sufficiently attempted until the current supply duration time T1, which is the corresponding time, elapses.

[Other embodiments]
[1] In the above first to third embodiments, one processor 18 performs ON / OFF control of the transistors 14 and 15. However, a processor that turns on the transistors 14 and 15 based on the ignition determination value and a processor that turns off the transistors 14 and 15 based on whether or not the squib 3 has ignited may be used. That is, the first processor may turn on the transistors 14 and 15 based on the ignition determination value, while the second processor may turn off the transistors 14 and 15 based on whether or not the squib 3 is ignited. Thus, when the first processor turns on the transistors 14 and 15 while the second processor turns off the transistors 14 and 15, the squib control device 10 has two processors, the first processor and the second processor. .

  [2] In Example 1-3 described above, one ECU 1 has one backup capacitor 11, and one squib 3 is connected to one backup capacitor 11. On the other hand, the vehicle may have the backup capacitor 11 outside the ECU 1, and one backup capacitor 11 may be shared by a plurality of ECUs 1, and a plurality of squibs 3 may be connected to one backup capacitor 11. When a plurality of squibs 3 are connected to one backup capacitor 11, the squib control device 10 adopts the configuration of the first embodiment, so that even if the backup capacitor 11 having the same amount of charge capacity as the conventional one is used, The backup time of the current supplied to each of the plurality of squibs 3 can be extended.

1 ECU (Engine Control Unit)
2 main battery 3 squib 10 squib control device 11 backup capacitors 14 and 15 transistor 17 differential amplifier 18 processor 19 memory 101 ignition determination unit 102 supply control unit 103 timer 104 short determination unit

Claims (9)

An ignition determination unit for determining whether or not the squib has ignited;
A supply controller that controls the supply of current to the squib based on whether the squib ignited;
A squib control device comprising: The supply control unit stops the supply of the current to the squib when the ignition determination unit determines that the squib is ignited.
The squib control device according to claim 1. The supply control unit continues the supply of the current to the squib when the ignition determination unit determines that the squib is not ignited,
The squib control device according to claim 1. The supply control unit, when the ignition determination unit determines that the squib is not ignited, the current to the squib at a time after a predetermined time has elapsed from the start of supply of the current to the squib. Stop supplying,
The squib control device according to claim 1. A short determination unit for determining whether a short has occurred at the input end of the squib or the output end of the squib,
The supply control unit controls the supply of the current to the squib based on whether or not the short circuit has occurred.
The squib control device according to any one of claims 1 to 4. When the supply control unit determines that the short circuit has occurred by the short determination unit, the supply of the current to the squib is stopped.
The squib control device according to claim 5. The supply control unit, when the short determination unit determines that the short-circuit has occurred, the current to the squib at a time after a predetermined time has elapsed from the supply start time of the current to the squib. Stop supplying,
The squib control device according to claim 5. The ignition determination unit determines whether or not the squib is ignited based on a voltage difference between the terminals of the squib;
The squib control device according to any one of claims 1 to 7. Determine if the squib ignited,
Controlling the supply of current to the squib based on whether the squib ignited;
Squib control method.

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