JPH0454047Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to an ignition circuit device for airbags.
More specifically, the present invention relates to a ignition circuit device for a vehicle occupant protection device.

[Conventional technology]

The air bag ignition circuit device is an ignition device that inflates the air bag to protect occupants from impact in the event of a car collision, etc. When a switch as a shock sensor is turned on, it ignites explosives electrically. It ignites the air and instantly inflates the air bag. Therefore, the ignition circuit device is required to have extremely high reliability, and in particular, reliable operation of the electric system of the detonator is required. A conventional example of such an ignition circuit device for an air bag is Japanese Utility Model Application No. 62-43878.

[Problem that the idea aims to solve]

When an automobile is equipped with two or more airbags, such as one for a passenger seat and one for a passenger seat, it is necessary to ensure that the two airbags are activated when necessary. However, although squibs usually open after ignition, they may become closed after ignition, and may not operate as expected. That is, in the conventional example shown in FIG. 4, there is no problem if either one of the two squib units q ₁ and q ₂ becomes open after firing, but when the squib units q ₁ and If one of q ₂ becomes shot after firing, most of the current will flow to the squib unit that shot after firing, for example squib unit q ₁ , and almost no current will flow to the other squib unit q ₂ . There was a problem with not being able to detonate. Furthermore, in the case of the conventional example shown in FIG. 5, the firing current I is divided into i ₁ and i ₂ in the squib circuit,
A current i ₁ flows through the squib unit q ₁ and a current i ₂ flows through the squib unit q ₂ . That is, the power consumed by squib units q ₁ and q ₂ is i ₁ /i ₁ +i ₂ , respectively.
i ₂ /i ₁ +i ₂ . Then, after one of them ignites,
If it becomes open (Fig. 5), the subsequent efficiency is the same, but if squib unit _q1 fires and shoots first (Fig. 5), then the efficiency is the same.
Problems remain, such as the current i ₁ flowing through the circuit is larger than the current i ₂ flowing through the circuit that requires the current, and the actually usable power i ₂ /i ₂ +i ₂ is extremely inefficient. In FIGS. 4 and 5, the symbol C represents a capacitor serving as a power source, S represents a shock sensor, B represents a charging battery, and r ₁ and r ₂ represent resistors. Therefore, the object of this invention is to provide at least an ignition circuit device in which even if one squib unit becomes shot, the remaining squib unit ignites and operates reliably as a detonator.

[Means to solve the problem]

In order to achieve the above-mentioned object, this invention provides a first resistor connected in series with the first squib unit, and a second resistor connected in series with the second squib unit connected to the power source. A diode is connected in parallel to the power source and connected in a forward direction with respect to the power supply from between the first squib unit and the first resistor to between the second squib unit and the second resistor. It is characterized by the fact that

[Effect]

When the sensor closes the circuit during a vehicle collision, an ignition current I is discharged, and in the squib circuit, currents i ₁ , i ₂ ,
i ₃ flows, i ₁ + i ₃ flows into squib unit Q ₁ , i 2 + i 3 flows into squib unit Q ₂ , i _{1 flows} into resistor R ₁ , and i ₁ flows into resistor R 1.
A current of i ₂ flows through each R ₂ . If squib unit _Q1 fires first and becomes open, only current _i2 flows and nothing else flows, allowing squib unit _Q2 to consume power.

【Example】

Below is the first drawing of the attached embodiment of this invention.
This will be explained with reference to FIG. 3. In these figures, the symbol _S1 indicates a shock sensor, which is normally in an open state, and a capacitor _C1 as a power supply is connected in series with this shock sensor _S1 , and the positive terminal side of this capacitor C1 is connected in series with the shock sensor _S1 . A squib circuit 10 is connected to. This squib circuit 10 includes two squib units Q ₁ and Q ₂ and two resistors.
R ₁ and R ₂ are bridge-connected, and further,
The intermediate portion between the squib unit Q ₁ and the resistor R ₁ and the intermediate portion between the squib unit Q ₂ and the resistor R ₂ are connected through a diode D ₁ connected in the forward direction with respect to the power supply, and the above-mentioned shock is transmitted from this squib circuit 10. Sensor S ₁
A power supply circuit 20 for charging the capacitor C1 is connected to the capacitor _C1 . Next, the operation of the ignition circuit device will be explained. First, the capacitor C ₁ is charged by the power supply circuit 20, usually an on-vehicle battery, and when the shock sensor S ₁ detects an impact such as a vehicle collision, its contact is closed and the capacitor C ₁ is discharged. At this time, the firing current I in the squib circuit 10 is i ₁ , i ₂ ,
The squib unit Q ₁ is divided into three parts: Q ₁ i ₃ .
= i ₁ + i ₃ , for squib unit Q ₂ Q ₂ i = i ₂ + i ₃ ,
In the resistor R ₁ , the current is R ₁ i=i ₁ , and in the resistor R ₂ , the current is R ₂ i=i ₂ . At this time, squib units Q ₁ and Q ₂ consume power efficiently. When squib unit _Q1 fires first and becomes open, only current _i2 flows,
Since the power does not flow elsewhere, power is efficiently consumed in the squib unit _Q2 . Furthermore, if squib unit Q ₁ fires first and enters the short state, current i ₁ + i ₂ + i ₃ will flow, and current i ₂ + i ₃ will flow through squib unit Q ₂ , allowing efficient power consumption. do. Conversely, when squib unit _Q2 fires first and enters the shot state, current _i1 + _i2 + _i3 flows, and current _i1 + _i2 flows through squib unit _Q1 . That is, the power consumption efficiency η in squib units Q ₁ and Q ₂ is: Q ₁ η=i ₁ +i ₂ /i ₁ +i ₂ +i ₃ >i ₁ /i ₁ +i ₂ Q ₂ η=i ₂ +i ₃ /i ₁ +i ₂ +i ₃ >i ₂ /i ₁ +i ₂ In the above embodiment, two squib units Q ₁ ,
The explanation has been given using an example using Q ₂ , but when using three squib units, it is possible to incorporate the squib circuit 10 into either one of the squib units Q ₁ or Q ₂ as shown in Fig. 2. To obtain a firing circuit device in which three squib units are reliably operated. Furthermore, when using four squib units, as shown in Figure 3, the squib units
By incorporating the squib circuit 10 in place of Q ₁ and Q ₂ , all four squib units can be operated reliably.

[Effect of the idea]

As is clear from the above description, the air bag ignition circuit device of this invention connects a squib unit and a resistor in series, connects at least two sets of these together via a bridge, and connects the middle between the two to a power source. Since the wiring is configured with diodes connected in the forward direction, even if one squib unit is shot or opens, the remaining squib units can be supplied with firing current and operate reliably, and the firing current is consumed efficiently. Therefore, it is possible to use a smaller capacitor, which is very advantageous in terms of cost and space savings.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a basic embodiment of the ignition circuit device for air bags according to this invention, Fig. 2 is a circuit diagram showing another embodiment, Fig. 3 is a circuit diagram showing still another embodiment, and Fig. The figure is a circuit diagram of a conventional ignition circuit device, and FIG. 5 is a circuit diagram illustrating another conventional embodiment and its operating mode. Q ₁ , Q ₂ ... Squib unit, R ₁ , R ₂ ... Resistor, D ₁ ... Diode, C ₁ ... Capacitor, S ₁
...Shock sensor.

Claims (1)

[Scope of utility model registration request] A first resistor connected in series with the first squib unit and a second resistor connected in series with the second squib unit are connected in parallel to the power supply. 1. A ignition circuit device for an air bag, characterized in that a diode is connected in the forward direction to a power source from between the first squib unit and the second resistor to the middle between the second squib unit and the second resistor.