JPH08133004A - Squib ignition circuit - Google Patents

Abstract

PURPOSE: To ignite a plurality of squibs securely by mounting a connection resistance corresponding to a plurality of squib ignition circuits between the respective plurality of squib ignition circuits and a power. CONSTITUTION: Negative electrode side of four squibs 141, 151, 161 and 171 are connected in common and grounded by a safing sensor 18. Gates of four switching elements 142, 152, 162 and 172 are connected in common and grounded by a drive transistor 191 to a control part 182. Four squib circuits 14-17 are respectively connected to a power bus 13 through four connection resistors 144, 154, 164 and 174. Whereby, the drive transistor 191 becomes ON state when a collision signal is detected from the control part 192 and allows the four switching elements 142, 152, 162 and 172 to be ON. The four squibs 141, 151, 161 and 171 are allowed to be ignition state securely when the safing sensor 18 is mechanically made ON.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squib ignition circuit, and more particularly to a squib ignition circuit having a structure in which a plurality of squibs are connected in parallel.

[0002]

2. Description of the Related Art In recent years, automobiles are often provided with airbags and seat belt pretensioners for passenger protection, but a gas generating agent is used for each driver or passenger airbag or pretensioner. It will be necessary to install a squib to ignite.

Therefore, a plurality of squibs are connected in parallel to the in-vehicle battery. However, since the DC resistance of each squib varies, when the in-vehicle battery and the squib are directly connected, most of the squibs have a small DC resistance. Since the electric current will flow, the reliable ignition of all squibs is not guaranteed. In order to solve the above-mentioned problems, there has been proposed a device in which a squib is connected to a vehicle-mounted battery via a current limiting circuit (see Japanese Patent Laid-Open No. 4-321454).

[0004]

However, in the ignition circuit according to the above proposal, it is necessary to install a current limiting circuit for each squib, which complicates the circuit and impairs the economical efficiency. The present invention has been made in view of the above problems, and an object thereof is to provide a squib ignition circuit that can reliably ignite a plurality of squibs and that has a simple configuration.

[0005]

A squib ignition circuit according to the present invention comprises a squib, a switching element connected in series to the positive side of the squib, a backup capacitor connected in parallel to the squib and the switching element, A plurality of squib ignition circuits, a safing sensor commonly connected to the negative side of the squibs of the plurality of squib ignition circuits, and a plurality of squib ignition circuits between each of the plurality of squib ignition circuits and the power supply. And a connection resistance corresponding to.

[0006]

In the squib ignition circuit according to the present invention,
When some of the squibs are short-circuited to the ground side, the backup capacitors installed corresponding to the other squibs are grounded via the connection resistance.

[0007]

1 is a circuit diagram of an embodiment of a squib ignition circuit according to the present invention, in which an airbag and a seat belt pretensioner are installed in a driver's seat and a passenger's seat, respectively. The positive electrode of the on-vehicle battery 11 is connected to the power supply bus 13 via the main backflow prevention diode 12.

The driver seat airbag squib circuit 14, the driver seat belt pretensioner 15, the passenger seat airbag squib circuit 16 and the passenger seat belt pretensioner squib circuit 17 have the same configuration. For example, the squib circuit of the driver airbag 14 includes a squib 141, a switching element 142 connected in series to the positive electrode side of the squib 141, and a backup capacitor 143 connected in parallel to the squib 141 * switching element 142.

The negative sides of the four squibs 141, 151, 161, and 171 are commonly connected and grounded via the safing sensor 18. The gates of the four switching elements 142, 152, 162 and 172 are commonly connected, and the control unit 19 is connected via the drive transistor 191.
Connected to 2. Also, four squib circuits 14, 15,
16 and 17 are four connection resistors 144 and 15 respectively.
4, 164 and 174 to the power bus 13.

The four connection resistors 144, 154, 16
Resistance values R of 4 and 174 are four squibs 141, 1
The DC resistances R _S of 51, 161, and 171 are almost the same. A backup capacitor 132 for the control unit is connected to the backflow of the main backflow prevention diode 13 via a backflow prevention diode 131 for the control unit to supply power to the control unit 192.

In this structure, when a collision signal is detected from the control unit 192, the driving transistor 191 is turned on and the four switching elements 142, 152 and 162 are turned on.
And 172 are turned on. Furthermore, if the safing sensor 18 is mechanically turned on, the four squibs 141, 151, 161, and 171 will be in an ignition state.

FIG. 2 shows an airbag squib 141 for a driver's seat.
It is an equivalent circuit when is short-circuited to the ground side or when the upstream side terminal and the downstream side terminal are short-circuited. That is, although the driver airbag back-up capacitor 143 is short-circuited, the other back-up capacitors 153, 163.
Since the positive side of each of 173 and 173 is grounded via two connection resistors connected in series, the power stored in the other backup capacitors 153, 163 and 173 is supplied to the corresponding squibs 151, 161, and 171. It

When the connection between the on-vehicle battery 11 and the power supply bus 13 is cut off, the electric power accumulated in the four backup capacitors 143, 153, 163 and 173 is passed through the control section backflow prevention diode 131. It is supplied to the control unit 192 and drives the control unit 192 to drive the four backup capacitors 143, 153, 163 and 1.
73 is discharged.

This discharge makes it possible to omit the discharge operation of the backup capacitor after the power is turned off.

[0015]

According to the squib ignition circuit of the present invention, the current limiting circuit can be omitted in the squib ignition circuit for igniting a plurality of squibs with one vehicle battery, and the circuit can be simplified. . Furthermore, when some squibs are short-circuited to the ground side, the backup capacitors installed corresponding to the other squibs are grounded via the connection resistance, preventing a short-circuit state and reliably igniting the other squibs. It becomes possible to do.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment.

FIG. 2 is an equivalent circuit when a squib is short-circuited.

[Explanation of symbols]

Reference numeral 11 ... Vehicle-side battery 12 ... Main backflow prevention diode 13 ... Power supply bus 131 ... Control section backflow prevention diode 132 ... Control section backup capacitor 141, 151, 161, 171 ... Squib 142, 152, 162, 172 ... Swinging element 143 , 153, 163, 173 ... Backup capacitors 144, 154, 164, 174 ... Connection resistance 18 ... Safing sensor 191 ... Drive transistor 192 ... Control unit

Claims (1)

[Claims] 1. A plurality of squib ignition circuits each including a squib, a switching element connected in series to a positive electrode side of the squib, and a backup capacitor connected in parallel to the squib and the switching element. A safing sensor commonly connected to the negative side of the squib of the plurality of squib ignition circuits, and a plurality of squib ignitions between each of the plurality of squib ignition circuits and a power source. Squib ignition circuit with connection resistance corresponding to the circuit.