JP2003040076A - Air bag device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow plural stages of development even if the conductive time W0 of a second sensor 15 is relatively short in an air bag device provided with the second sensor 15 made conductive by mechanical operation when impact force is applied, in order to prevent malfunction caused by noise in addition to a first sensor 14 for detecting the impact force applied to a vehicle body. SOLUTION: In a first operation mode Lo, the impact force is applied to the vehicle body, and a processing circuit supplies a first ignition control signal to a first switching circuit 24 by the output of the first sensor 14 to become conductive to thereby perform the ignition operation of a first squib 21. At this time, a charging control signal is supplied to a charging switching circuit 29 to charge an ignition power capacitor 27. A second ignition control signal is then supplied to a second switching circuit 35 to become conductive. Power from the ignition power capacitor 27 is thereby supplied to a second squib 22. In a second operation mode Hi, a third ignition control signal is supplied to a simultaneous ignition switching circuit 33 simultaneously with the first ignition control signal of the first switching circuit 24, and the first and second squibs 21, 22 are simultaneously ignited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag which is mounted on a vehicle such as an automobile and protects an occupant by being deployed when a collision accident occurs. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, a vehicle is equipped with an air bag in order to protect passengers such as a driver of a vehicle when an accident occurs. The airbag is usually folded in a small size and is used for steering, dashboard, doors, etc.
It is stored in the passenger compartment. When a large impact force or acceleration is detected due to an accident or the like, the airbag rapidly expands and is deployed around the body to protect the occupant. A multi-stage deployment airbag system that can be deployed over a plurality of stages is also used to more reliably protect passengers.

FIG. 10 is a block diagram showing a simplified electrical configuration of a control device of a conventional multi-stage deployment airbag system. Ignition of the airbag is performed by applying an ignition current supplied from an ignition power supply 3 to the first squib 1 and the second squib 2 respectively. 1st squib 2 and 2nd
The squib 2 includes an electric heater and is heated by energization,
Ignition is performed to generate gas that inflates and deploys the airbag. Normally, the airbag needs to be surely deployed only when necessary, and therefore the deployment is performed on condition that the safing sensor 4 and the G sensor 5 detect the collision state twice. The safing sensor 4 is a mechanical switch that operates so as to conduct when a sudden increase in acceleration or impact force is detected. The G sensor 5 detects the acceleration and gives an electric output corresponding to the detected acceleration to the control circuit 6. The control circuit 6 controls the switching circuits 7 and 8 according to the output from the G sensor 5. When the safing sensor 4 is turned on and the switching circuits 7 and 8 are turned on, an ignition current flows through the 1st squib 1 and the 2nd squib 2 to ignite.

In the multi-stage deployment airbag system, the mode switch 9 is switched to switch between Hi mode, Lo mode and OF.
The F mode can be switched. Table 1 below shows the ignition states of the 1st squib 1 and the 2nd squib 2 in each mode.

[0005]

[Table 1]

FIG. 11 is a waveform diagram showing ignition timing in the Lo mode. In Hi mode, 1st squib 1
In the Lo mode, the 1st squib 1 is turned on as shown in FIG. 11 (2) by the ON operation of the safing sensor 4 shown in FIG. 11 (1).
As described above, the second squib 2 needs to be turned on after the time t21 and then turned on from the off squib 2 at the time t22 in FIG. 11 (3) when the time W11 (for example, 100 ms) has elapsed. However, the ON time W1 of the safing sensor 4
2 is, for example, only several tens of ms and less than 100 ms. Therefore, the safing sensor 4 is 100 ms.
The ON state must be maintained for a while.

[0007]

In the conventional multistage airbag system as shown in FIG. 10, Lo shown in Table 1 is used.
When operating in the mode, the safing sensor 4 needs to be kept in the ON state for about 100 ms or more.
However, in the currently available mechanical safing sensor 4, the time W12 that can be kept ON is less than 100 ms as described above, so at the time t22 when the ignition of the second squib 2 is attempted, the safing sensor 4 Even if the control circuit 6 drives the switching circuit 8 to the ON state, the ignition current cannot flow to the second squib 2 even if the switch contact of No. 2 is already opened. Therefore, the time W11 must be set shorter than the desired time 100 ms, and therefore, the safety protection of the occupant due to the deployment operation of the airbag becomes insufficient.

An object of the present invention is to provide an airbag device which can reliably deploy an airbag in a plurality of stages.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an air bag device having a plurality of ignition means, in which a mechanical acceleration switch provided in a path for supplying an ignition current to the first ignition means is in an energized state. In addition, the airbag device is characterized in that a capacitor for supplying an ignition current to the second ignition means is charged.

The present invention is also directed to an airbag device having a plurality of stages of ignition means for deploying the airbag,
In response to the first ignition control signal, first ignition means 23 for igniting the airbag deployed as the first stage, and for igniting the airbag deployed as the second stage in response to the second ignition control signal. The second ignition means 41 for performing, the ignition power supply for supplying an ignition current to the first and second ignition means, the first sensor 14 for detecting the airbag deployment condition, and the interposition between the ignition power supply and the first ignition means. The second sensor 15 which detects the airbag deployment condition and conducts by a mechanical operation, the ignition power capacitor 27, and the first ignition control signal to the first ignition means in response to the output of the first sensor. And a control means for charging the ignition capacitor for supplying the ignition current to the second ignition means.

In accordance with the present invention, a first device provided in an airbag device, as will be described below in connection with FIGS.
When the first and second ignition control signals are respectively applied, the first and second ignition means for igniting the airbag deployed as the second stage and the second stage respectively perform ignition for airbag deployment by energization. Further, in this airbag device, the first and second ignition means are operated even though the impact force due to an accident does not act on the vehicle body of the automobile due to the malfunction of the first sensor 14 and the control means. A second sensor 15 having a mechanical structure is provided in order to prevent the expansion and the expansion.

The first and second sensors 14 and 15 may be fixed to, for example, the vehicle body of an automobile, and may have a structure for detecting acceleration due to impact force when an accident occurs in the front-rear direction. The first sensor 14 may be configured to derive an electric signal having a level corresponding to acceleration with relatively high accuracy, for example. The second sensor 15 is supported by a spring so that the permanent magnet piece can be displaced in the front-rear direction of the vehicle body in the vicinity of, for example, a reed switch provided on the vehicle body, and when the acceleration acts on the permanent magnet piece, the permanent magnet piece. May be displaced against the spring force, which changes the strength of the magnetic field that acts on the reed switch and changes the switching state of the reed switch. Alternatively, the mass body such as a permanent magnet piece may be supported by a spring, and the displacement of the mass body may be configured to be detected electrically or optically, and may be realized by other configurations. May be done.

The control means generates the first ignition control signal in response to the output of the first sensor and supplies the first ignition control signal to the first ignition means 23, and at the same time, the ignition power capacitor 27 is charged by the electric power from the ignition power source. Therefore, the second sensor once conducts, then shuts off, and even in the shut-off state, the second ignition control signal of the control means uses the charged electric power of the ignition power condenser to output the second ignition means. 41
The second ignition means can be ignited. Therefore, even if the second sensor is activated after the ignition condition is satisfied due to the occurrence of a shock on the vehicle body and the second sensor is in the conductive state, the ignition is performed even if the second sensor is cut off. The second ignition means can be ignited by using the power of the power capacitor. Thus, the airbag can be ignited in two stages. The present invention is also implemented in connection with not only two stages but also a plurality of stages of three or more stages of deployment airbag.

According to the present invention, the control means is connected in series to the processing circuit for generating the first and second ignition control signals in response to the output of the first sensor and the ignition power capacitor.
Switching circuit 2 for charging which is conducted by the processing circuit
9, the first ignition means includes a first squib 21 and a first switching circuit 24 connected in series to the first squib and electrically connected by a first ignition control signal. Has a second squib 22 and a second switching circuit 35 that is connected in series with the second squib and is turned on by a second ignition control signal.

According to the invention, the control means includes a processing circuit realized by a microcomputer and the like, and a charging switching circuit 29 for supplying charging power to the ignition power capacitor from the ignition power source through the second sensor. Will be realized. The first ignition means is realized by connecting the first switching circuit 24 to the first squib 21 in series, and similarly, the second ignition means is realized by connecting the second switching circuit 35 to the second squib 22 in series. To be done. Therefore, at the same time that the first switching circuit is turned on by the first ignition control signal to ignite the first squib, at the same time, the same signal as the first ignition control signal is generated, or simultaneously with the first ignition control signal. The signal can be supplied to the charging switching circuit 29 as a charging control signal to charge the capacitor 27.

Further, according to the present invention, in an airbag apparatus having a plurality of stages of ignition means for inflating an airbag by energization, in response to a first ignition control signal, the airbag deployed as the first stage is ignited. 1 ignition means 23, second
Second ignition means 41 for responsive to the ignition control signal to ignite the airbag deployed as the second stage; first and second ignition means 41;
An ignition power supply that supplies an ignition current to the ignition means, a first sensor 14 that detects an airbag deployment condition, an ignition power supply and a first sensor 14.
And a second sensor 15, which is interposed between the second ignition means and the second ignition means, detects an airbag deployment condition and conducts by a mechanical operation, an ignition power capacitor 27, and a first sensor in response to an output of the first sensor. A first ignition control signal is supplied to the first ignition means, and after the first ignition control signal is generated, the second ignition control signal is supplied to the second ignition means according to a predetermined condition, and the first ignition means is energized. Energization detecting means 44 for detecting
And a holding unit 45 that holds the energization detection output in response to the output of the energization detection unit and derives a charging control signal to enable charging of the capacitor.

According to the present invention, as will be described below with reference to FIGS.
When the first and second ignition control signals are respectively applied, the first and second ignition means for igniting the airbag deployed as the second stage and the second stage respectively perform ignition for airbag deployment by energization. Further, in this airbag device, the first and second ignition means 23, despite that the impact force due to an accident or the like does not act on the vehicle body of the automobile due to the malfunction of the first sensor 14 and the control means,
A second sensor 15 having a mechanical structure is provided in order to prevent the airbag from inflating and expanding due to the operation of 41.

The control means generates a first ignition control signal in response to the output of the first sensor and applies it to the first ignition means 23.
The energization detection means 4 indicates that the ignition current has flowed to the first ignition means.
4, and the holding means 45 derives a charging control signal obtained by holding the energization detection output, so that the ignition power capacitor 27 can be charged. In this way, the ignition power capacitor 27 is charged by the power from the ignition power source.

Therefore, the second ignition control signal for the second ignition control signal of the control means is made by using the electric power charged in the ignition electric power condenser 27 even when the second sensor 15 is once turned on and then turned off. Is given to the second ignition means 41, the second ignition means 41 can be ignited. Therefore, even if the second sensor is activated after the ignition condition is satisfied due to the occurrence of a shock on the vehicle body and the second sensor is in the conductive state, the ignition is performed even if the second sensor is cut off. The second ignition means can be ignited by using the power of the power capacitor. Thus, the airbag can be ignited in two stages.
Therefore, the conduction time of the second sensor (hence FIG. 8)
When the time t13 of (2) is less than the generation time of the first ignition control signal (and therefore earlier than the time t15 of FIG. 8C), of course, conversely, the conduction time of the first sensor (Thus, the time t13a in FIG. 9 (2)) is the first
Even when the ignition control signal is higher than the control signal (see FIG. 9).
When the time t15a in (3) is later than the time t15a), the ignition power capacitor 27 can be charged over the conduction period of the second sensor 15 and sufficient charge can be stored. By using the electric power of the ignition power condenser, the second ignition control signal can be generated and the second ignition means 41 can be operated even after the second sensor is cut off. The present invention is also implemented in connection with not only two stages but also a plurality of stages of three or more stages of deployment airbag.

Further, in the invention, the control means is responsive to the output of the first sensor, and a processing circuit for generating first and second ignition control signals, and a charging circuit connected in series to an ignition power capacitor. A switching circuit 29, the first ignition means has a first squib 21 and a first switching circuit 24 connected in series to the first squib and electrically connected by a first ignition control signal; The ignition means is connected in series with the second squib 22 and the second squib
The second switching circuit 35 is made conductive by the ignition control signal, the energization detection means 44 is interposed in series with the first ignition means, and the current detection element 51 for detecting the current and the ignition current of the current detection element are provided. When the value is greater than or equal to a predetermined value,
Energization detection level discrimination circuit 52 for deriving an energization detection output
The holding means 45 has a holding capacitor 56 charged by the output of the energization detection level discrimination circuit, and when the output of the holding capacitor is equal to or more than a predetermined value,
And a charge control level discriminating circuit 59 for supplying a charge control signal to the charge switching circuit to conduct the charge switching circuit.

According to the present invention, as the specific electrical configuration will be described later with reference to FIG. 6, when the ignition current flows through the current detecting element 51 of the energization detecting means, for example, the current detecting resistor. It is possible to detect the voltage drop at the level drop by the level discriminating circuit 52 for detecting energization. The output of the energization detection level discriminating circuit is held by an integral type holding capacitor 56 that constitutes a time constant circuit 58, and the output voltage of the holding capacitor 56 is level discriminated by an ignition control level discriminating circuit 59 and charged. Control signal can be obtained.

According to the present invention, it is confirmed that the ignition current supplied to the first ignition means 23 is at least a current value sufficient to ignite the first ignition means, and the ignition power is confirmed. The charging capacitor 27 is charged. Therefore, when the power of the ignition power source is decreasing, the ignition power capacitor is not charged, only the ignition operation of the first ignition means is reliably performed, and the ignition operation of the second ignition means 41 is not performed. At the very least, ensure passenger safety protection.

Further, the present invention is characterized in that a current limiting circuit for setting an upper limit value of current is interposed in series with the first and second switching circuits.

According to the present invention, by providing the current limiting circuit in the first and second ignition means, the power consumption of the ignition power source and the ignition power capacitor is suppressed, and unnecessary power consumption is prevented. The ignition operation of the second ignition means can be reliably performed.

The present invention further includes a simultaneous ignition switching circuit 33, which is interposed between the second sensor and the second ignition means, and which conducts in response to the third ignition control signal, and the first and second ignition circuits.
A mode setting means 39 for setting an operation mode, the processing circuit is responsive to the output of the mode setting means, and in the first operation mode, generates the first and second ignition control signals at different times, The second operation mode is characterized in that the first and third ignition control signals are simultaneously generated.

According to the invention, of the plurality of stages of ignition means, the first operation mode Lo in which the ignition operations of the respective ignition means are shifted and the second operation mode Hi in which the ignition means are simultaneously operated. And are set by the mode setting means 39. In the mode setting means, each operation mode is set by a switch realized by, for example, a manual operation, or is set by arithmetic processing of the output of the first sensor. In the second operation mode, the electric power of the ignition power source is supplied to the first ignition means via the second sensor, and the electric power of the ignition power source is supplied to the second ignition means 41 via the second sensor and the simultaneous ignition switching circuit 33. . In this way, the first and second ignition means can be operated simultaneously by the electric power of the ignition power supply without having to perform the charging operation of the ignition power capacitor used in the first operation mode.

In the present invention, the second sensor 15 is interposed between the ignition power supply and the first ignition means, and the ignition power supply and the second
The structure may not be interposed between the ignition device and the ignition device.

[0028]

1 is a block diagram showing the overall configuration of an embodiment of the present invention. The vehicle body of an automobile is provided with a G sensor 14 that is a first sensor and a second sensor 15 that can be called a safing sensor that conducts by a mechanical operation. The first sensor 14 derives an electric signal having an electric level such as a voltage corresponding to an acceleration acting in the front-rear direction of the vehicle body 2 and gives it to the processing circuit 16. The processing circuit 16 is realized by, for example, a microcomputer. Second sensor 1
A mass body 5 such as a permanent magnet piece is provided so as to be displaceable in the front-rear direction of the vehicle body against the spring force of a spring due to the acceleration acting on the vehicle body. The reed switch whose state changes is fixed, and when a condition such as an impact force acting on the vehicle body acts and the airbag deployment condition is satisfied, the reed switch conducts. The electric power of the ignition power source 17 realized by the battery is the booster circuit 1
It is boosted by 8 and given to the line 19 from the second sensor 15.

The multistage deployment airbag is provided with a first squib 21 and a second squib 22. The ignition operation of the first and second squibs 21 and 22 inflates and deploys the airbag. The air bag is provided with a throttle for discharging the gas inside.

The first squib 21 has a first switching circuit 2 including switching transistors TR1 and TR2.
3 are connected in series. Thus, the first ignition means 24 is configured. A first ignition means 24 is connected to the line 19 via a current limiting circuit 25.

A discharge resistor 28 is connected in parallel to the ignition power capacitor 27. The capacitor 27 has
The switching transistor TR3 forming the charging switching circuit 29 is connected in series. The charging switching circuit 29 is connected to the line 1 via the current limiting circuit 32.
9 is connected.

A simultaneous ignition switching circuit 33 including a switching transistor TR4 is connected to the second squib 22 of the airbag. The simultaneous ignition switching circuit 33 is connected to the line 19 via a current limiting circuit 34.

The second squib 22 is connected in series with a second switching circuit 35 formed by connecting switching transistors TR5 and TR6 in series. Second
The squib 22 and the second switching circuit 35 constitute second ignition means 41. This second switching circuit 35
Is connected to a connection point 37 of the ignition power capacitor 27 via a current limiting circuit 36. A first ignition control signal is given from the processing circuit 16 to the bases that are the control terminals of the switching transistors TR1 and TR2 of the first switching circuit 24, and similarly, to the bases of the switching transistors TR5 and TR6 of the second switching circuit. Is supplied with a second ignition control signal from the processing circuit 16, and the switching transistor T of the switching circuit 29 is
A charging control signal is applied to R3 from the processing circuit 16, and a third ignition control signal is applied from the processing circuit 16 to the switching transistor TR4 of the switching circuit 33.

A mode setting circuit 39 is connected to the processing circuit 16. This allows the first and second squibs 2
1st operation mode Lo in which 1 and 22 are shifted and multistage expansion operation is performed
And a second operation mode Hi in which the first and second squibs 21, 22 are simultaneously ignited is switched and set. In such a mode setting, the processing circuit 16 sets the first sensor 14
May be configured to be calculated and set in response to the output of.

FIG. 2 is a flow chart for explaining the operation of the processing circuit 16 of FIG. When a collision of the vehicle body or the like occurs and an impact force is applied, the output of the first sensor 14 is given to the processing circuit 16, and the processing circuit 16 performs the step
At, the ignition request operation of the squibs 21 and 22 is started. When it is determined in step s2 that the mode setting circuit 39 has set the first operation mode in which the airbag is expanded in multiple stages, the first ignition control signal and the charging control signal are transmitted in the next step s3. Is generated,
The switching transistors TR1, TR2; TR3 are turned on.

FIG. 3 is a waveform diagram for explaining the operation in the first operation mode in the embodiment shown in FIGS. 1 and 2. The output of the first sensor 14 is shown in FIG. 3A, and it is assumed that the impact force acts on the vehicle body at time t1 and the acceleration acts. At the time of this impact, the second sensor 15 conducts at times t2 to t8 as shown in FIG. 3 (2). The conduction period W0 of the second sensor 15 is
For example, it is several 10 ms. The switching state of the switching transistor TR1 in step s3 of FIG. 2 is shown in FIG.
The switching state of No. 2 is shown in FIG. 3 (4), and the switching state of the switching transistor TR3 for charging is shown in FIG. 3 (5). In step s4 of FIG. 2, these switching transistors TR1, TR2, and TR3 are kept conductive during time t4 to t5 for a time W1, and in step s5, these switching transistors TR1, TR2, and T3 are maintained at time t5.
Block R3.

When the switching transistors TR1 and TR2 of the first switching circuit 24 become conductive,
From the ignition power supply 17 to the first squib 21, the booster circuit 2
8, the ignition current is supplied through the second sensor 15 and the current limiting circuit 25, and the expansion operation of the first stage is performed. At this time, as described above, the switching transistor TR3 for charging is turned on, and the ignition power capacitor 27 is supplied with power from the line 19 through the current limiting circuit 32.
The ignition power capacitor 27 is charged and the voltage at the connection point 37 rises. The voltage at this connection point 37 is as shown in FIG. The ignition power capacitor C is charged at times t4 to t8 when the second sensor 15 is conducting and the switching transistor TR3 is conducting, and holds the charge accumulated at times t8 to t6.

As shown in step s6 in FIG. 2, time W2 is measured from time t5, and at time t6,
In step s7, the switching transistor TR that constitutes the second switching circuit 35 of the second ignition means 41.
5, TR6 are conducted. At this time, the switching transistor TR4 of the simultaneous ignition switching circuit 33 is
It remains blocked as shown in FIG. 3 (7). Figure 3
(8) shows the switching state of the switching transistor TR5, and FIG. 3 (9) shows the switching state of the switching transistor TR6. Thus, at time t6 when a relatively long time W4 has elapsed from time t1, the second
Even if the sensor 15 is cut off, the ignition power condenser 2
The electric power from 7 can be used to provide ignition power to the second squib 22. The time W4 may be 100 ms, for example.

In step s8 of FIG. 2, the switching transistors TR5 and TR6 are cut off at time t7 when time W3 has elapsed from time t6, and thus in step s9, a series of operations in the first operation mode Lo is completed.

In FIG. 4, the second mode is set by the mode setting circuit 39.
FIG. 3 is a waveform diagram for explaining the operation of the embodiment shown in FIGS. 1 and 2 when the operation mode Hi is set. In the second operation mode setting circuit 39, the second
When the operation mode Hi is set, the process proceeds from step s1 of FIG. 2 to step s2 to step s11. FIG. 4A shows the output waveform of the first sensor 14, and FIG.
(2) shows the switching state of the second sensor 15. At step s11, the switching transistor TR1 is turned on for a period W1 from time t4 to t5 as shown in FIG. 4C, and similarly, the switching transistor TR2 is turned on as shown in FIG.
It conducts as shown in (4). As a result, the ignition current flows through the first squib 21 in the same manner as described above, and the ignition operation is performed. Similarly to this, the switching transistor TR4 in the simultaneous ignition switching circuit 33,
One of the switching transistors TR6 of the second switching circuit 35 is electrically connected as shown in FIGS. 4 (7) and 4 (9).

Thus, the switching transistor TR
1, TR2; TR4, TR6 conduction period W1 is maintained. Therefore, an ignition current flows from the ignition power source 17 to the second squib 22 through the booster circuit 18, the second sensor 15, the line 19, the current limiting circuit 34, the switching transistor TR4, and the switching transistor TR6, and the second squib 22 The ignition operation of the first squib 21
At the same time. In step s13 of FIG. 2, time t
5, switching transistors TR1, TR2;
TR4 and TR6 are cut off. In such a second operation mode Hi, the charging control switching transistor T
R3 and the switching transistor TR5 of the second switching circuit 35 remain cut off as shown in FIGS. 4 (5) and 4 (8), respectively, and the voltage at the connection point 38 of the ignition power capacitor 27 is as shown in FIG. It is zero as shown in (6).

FIG. 5 is a block diagram showing the overall structure of another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIGS. 1 to 4 described above, and corresponding parts are designated by the same reference numerals. It should be noted that in this embodiment, the energization detecting means 44 is connected in series with the first ignition means 23.
Is connected to detect the ignition current flowing through the first ignition means 23. The output of the energization detecting means 44 is given to the holding means 45. As a result, the holding means 45 causes the switching transistor TR3 of the charging switching circuit 29 to
A charging control signal is given to make it conductive so that the charging power capacitor 27 can be charged.

FIG. 6 shows the energization detecting means 44 shown in FIG.
FIG. 6 is a circuit diagram showing a specific electrical configuration of a holding means 45 and a holding means 45. The line 47 of the first ignition means 23 is provided with the current detecting resistor 51 of the energization detecting means 44. One input of the energization detection level discrimination circuit 52 is connected to the line 47, and the other input is connected to the first reference voltage source 53. The ignition current flowing through the first ignition means 23 is large enough to ignite the first squib 21, so that the voltage drop across the resistor 51 is greater than or equal to the first reference voltage of the first reference voltage source 53. Then, the output of the energization detection level discrimination circuit 52 is turned on, and the line 54 is supplied with a predetermined voltage V1. When the voltage drop of the resistor 51 is less than the first reference voltage, the impedance of the output connected to the line 54 of the energization detection level discrimination circuit 52 has a large open value.

A holding capacitor 56 is connected to the line 54 in the holding means 45. This capacitor 56
A resistor 57 is connected to. Thus, the holding capacitor 56 and the resistor 57 form a time constant circuit 58. The output of the time constant circuit 58 is given to one input of the charge control level discrimination circuit 59. The second reference voltage source 61 is connected to the other input of the charge control level discrimination circuit 59.
A second reference voltage from The charge control level discrimination circuit 59 makes the output switching transistor 62 conductive when the voltage on the line 54 of the time constant circuit 58 becomes equal to or higher than the second reference voltage of the second reference voltage source 61.
As a result, the line 48 becomes low level, and the switching transistor TR3 of the switching circuit 29 for charging is
Conducts.

Thus, when an ignition current large enough to ignite the first squib 21 flows through the line 47 of the first ignition means 23, the charging voltage in the line 54 of the holding capacitor 56 becomes high. When the ignition current in the line 47 is equal to or larger than the value corresponding to the second reference voltage source 61, the switching transistors 62 and TR3 are turned on,
The ignition power capacitor 27 is charged during the ignition operation of the first squib 21.

Line 5 of level discriminating circuit 59 for charge control
The impedance of the input connected to 4 is high, so the holding capacitor 56 is
It has a smaller capacity than. Thus, the energization detecting means 4
4 and the holding means 45 are realized in a small size, and can be realized by an electric circuit element independently of the processing circuit 16. Therefore, the calculation processing load of the processing circuit 16 can be reduced, and the speed of the calculation operation of the processing circuit 16 can be correspondingly improved.

The first ignition means 2 is operated by the energization detection means 44.
Only when it is detected that the ignition current necessary for the ignition operation of the first squib 21 has flowed to the switching element 3, the holding transistor 45 causes the switching transistor TR3 of the charging switching circuit 29 to become conductive. Therefore, while the output voltage of the ignition power supply 17 is decreasing, the ignition operation of the first squib 21 is performed simultaneously with the ignition power condenser 2
It is prevented that the charging of No. 7 is started, and therefore the ignition current sufficient for the ignition of the first squib 21 does not flow.
Thus, even when the output voltage of the ignition power source 17 is reduced, the first and second squibs 21, 22 of the airbag are
Of these, at least the first squib 21 can be reliably ignited.

FIG. 7 is a flow chart for explaining the operation of the processing circuit 16 in the embodiment shown in FIGS. 5 and 6, and FIG. 8 explains the operation in the embodiment shown in FIGS. FIG. 6 is a waveform diagram for doing so. Steps u1 to u13 in FIG. 7 correspond to steps s1 to s13 of FIG. 2 in the above-described embodiment, respectively, and are shown in FIGS. 8 (1) to 8 (4) and 8 (5) to 8
The respective waveforms of (9) correspond to the above-described FIGS. 3 (1) to 3 (4) and 3 (5) to 3 (9), respectively. When the operation proceeds from step u1 to step u2 in FIG. 7 and the first operation mode Lo is set in the mode setting circuit 39, in the next step u3, the first ignition control signal is changed to the first ignition control signal.
Switching transistors TR1 and TR of the ignition means 23
2 and continues for the time W1 set in step u4, and cuts off the switching transistors TR1 and TR2 in step u5. 8 (1) shows an output waveform of the first sensor 14, and FIG.
(2) shows the output waveform of the second sensor 15. As described above, in steps u3 to u5 of FIG. 7, the switching transistors TR1 and TR2 are connected to the switching transistors TR1 and TR2 shown in FIGS.
As shown in FIG. 7, the power is conducted for the time W1 from time t14 to time t15. The time t15 when the switching transistors TR1 and TR2 change from the conductive state to the cutoff state is later than the time t13 when the second sensor 15 changes from the conductive state to the cutoff state.
As a result, an ignition current flows through the first squib 21.

In step u6 of FIG. 7, at time t16 when time W2 has elapsed from time t15, in step u7 the switching transistors TR5 and TR6 are turned on for a predetermined time W3 in step u8, and thereafter,
At time t17, the switching transistors TR5 and TR6 are cut off in step u9 of FIG. Thus, in step u10, a series of operations ends. Steps u11 to u13 of FIG. 7 are the same as steps s11 to s13 of FIG. 2 in the above-described embodiment. When the ignition current flowing through the first squib 21 is sufficiently large, the energization detecting level discriminating circuit 52 of the energization detecting means 44 outputs the output shown in FIG. 8 (4a) to the line 54. As a result, the output voltage of the holding capacitor 56 of the holding means 45 becomes as shown in FIG. 8 (4b). Therefore, the output of the charge control level discrimination circuit 59 is as shown in FIG. 8 when the output voltage of the holding capacitor 56 is from time t14 to time t18.
It becomes high level as shown in (4c). This causes the switching transistor 62 to move from time t14 to time t1.
It remains conductive for a period of eight. Therefore, the switching transistor T in the charging switching circuit 29 is
R3 is time t14 to t1 as shown in FIG.
Conducting at 8. As a result, in the charging power capacitor 27, the time t14 to t13 when the second sensor 15 is conductive and the switching transistor TR3 is conductive.
Will be charged at. Then, from time t13 to t1
At 6, the charge is retained. Thus, the output voltage of the connection point 37 of the charging power capacitor 27 is as shown in FIG. 8 (6).

Time t16 is a time when a predetermined time W2 has elapsed from the end time t15 of the first ignition control signal. The simultaneous ignition switching transistor TR4 remains cut off as shown in FIG.
Switching transistors TR5, TR of the ignition means 41
As shown in FIGS. 8 (8) and 8 (9), 6 is turned on for a predetermined time W3 from time t16 to time t17. Thus, the second squib 22 is ignited. In this way, from the time t11 when the impact is detected by the first sensor 14 and the airbag deployment condition is satisfied, the second squib 22 is ignited at the time t16 when the time W4 elapses. Squib 2
2 will be ignited.

FIG. 9 is a waveform diagram for explaining another operation in the embodiment shown in FIGS. Figure 9
The waveforms of (1) to 9 (9) correspond to the waveforms of FIGS. 8 (1) to 8 (9) described above, respectively. Particularly in the operation of FIG. 9, the time t1 of the second sensor 15 shown in FIG.
From the processing circuit 16 to the switching transistor TR of the first ignition means 23 during the period of conduction at 2 to t13a.
1, TR2 are given a control signal for the first expansion, and these switching transistors TR1, TR2 are turned on at time t1.
It conducts only for the time W1 of 4 to t15a. The time t15a at which the switching transistors TR1 and TR2 change from the conductive state to the cutoff state is earlier than the time t13a at which the second sensor 15 changes from the conductive state to the cutoff state. Other operations in FIG. 9 are the same as the operations in FIG. 8 described above. Further, the second operation mode Hi in the embodiment of FIGS.
The operation of is similar to that of the above-described embodiment.

[0052]

As described above, according to the present invention, the second sensor 15 which conducts mechanically and conducts in order to prevent malfunction due to noise of the air bag is provided with the ignition power source and the first and second ignition means 24. , 29, and when an accident occurs, the first sensor 14 detects the airbag deployment condition by the impact force acting on the vehicle body of the automobile, and the first ignition means 24 is provided with the first ignition means 24 by the function of the control means. An ignition control signal is applied, and the second sensor 15 is in conduction at this time, whereby the first ignition means ignites and the airbag is deployed in the first stage. The electric power of the ignition power supply is applied to the capacitor 27 for ignition power to which the first ignition control means is applied to the first ignition means, and the electric charge is accumulated. Therefore, thereafter, even if the second sensor 15 is cut off, the power of the ignition power capacitor 27 is used to provide the second ignition control signal to the second ignition means 41 to ignite the second ignition means. Then, the second stage airbag deployment can be performed.

Thus, according to the present invention, the second sensor 15
Even if the time period during which the mechanical operation of (1) conducts is short, it is possible to deploy the airbag in multiple stages.

Further, according to the present invention, when the current supplied to the first ignition means 23 is a large current capable of sufficiently igniting the first ignition means 23, the holding means 45 can charge the capacitor. As a result, at least the first ignition means can be ignited even when the output power of the ignition power source is reduced, and the safety of the occupant can be ensured to a minimum. The energization detection means 44 and the holding means 45 are provided separately from the control means.
Since it can be realized by using electronic circuit parts,
Also, the operation of the second ignition means can be accurately performed without causing an undesirable variation in time delay. The control means can be realized by, for example, a microcomputer.

First and second switching circuits 24, 2
9, and thus in series with the first and second ignition means, a current limiting circuit is interposed whereby the output of the ignition power supply and the ignition power capacitor 27 provides the current required to ignite the first and second ignition means. It is possible to supply the electric current, and to prevent supply of a large and useless electric current.

Further, according to the present invention, in the first operation mode, the first and second ignition means are operated at different times,
Switching circuit 33 for simultaneous ignition in the second operation mode
Is generated at the same time as the first ignition control signal by the third ignition control signal, and in this way, the airbag can be deployed in plural stages simultaneously.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of a processing circuit 16 in FIG.

FIG. 3 is a waveform diagram for explaining an operation in a first operation mode in the embodiment shown in FIGS. 1 and 2.

FIG. 4 is a waveform diagram for explaining the operation of the embodiment shown in FIGS. 1 and 2 when the second mode is set by the mode setting circuit 39.

FIG. 5 is a block diagram showing an overall configuration of another embodiment of the present invention.

FIG. 6 is a diagram showing the energization detecting means 44 and the holding means 4 shown in FIG.
5 is a circuit diagram showing a specific electrical configuration with FIG.

7 is a flowchart for explaining the operation of processing circuit 16 in the embodiment shown in FIGS. 5 and 6. FIG.

FIG. 8 is a waveform chart for explaining the operation in the embodiment shown in FIGS. 5 to 7.

9 is a waveform diagram for explaining another operation in the embodiment shown in FIGS. 5 to 8. FIG.

FIG. 10 is a block diagram showing a simplified electrical configuration of a control device of a conventional multi-stage deployment airbag system.

FIG. 11 is a waveform diagram showing ignition timing in Lo mode.

[Explanation of symbols] 14 First sensor 15 Second sensor 16 Processing circuit 17 Ignition power supply 21 First Squib 22 Second Squib 23 First Ignition Means 24 First switching circuit 25, 32, 34, 36 Current limiting circuit 27 Capacitor for ignition power 29 Charging switching circuit 33 Switching circuit for simultaneous ignition 35 Second switching circuit 41 Second ignition means TR1 to TR6 switching transistors 39 Mode setting circuit 44 Energization detection means 45 holding means 51 Current detection resistor 52 Level discriminating circuit for energization detection 53 First reference voltage source 56 holding capacitor 59 Level control circuit for charge control 61 Second reference voltage source

Claims (7)

[Claims] 1. An air bag device comprising a plurality of ignition means, wherein a second acceleration means is ignited when a mechanical acceleration switch provided in a path for supplying an ignition current to the first ignition means is in an energized state. An airbag device characterized in that a capacitor for supplying an electric current is charged. 2. An airbag device comprising a plurality of stages of ignition means for deploying an airbag, the first ignition means responsive to a first ignition control signal to ignite the airbag deployed as the first stage. 23, a second ignition means 41 for igniting the airbag deployed as the second stage in response to the second ignition control signal, an ignition power supply for supplying an ignition current to the first and second ignition means, and A first sensor 14 that detects a bag deployment condition, and a second sensor that is interposed between an ignition power source and a first ignition means, detects the airbag deployment condition, and conducts a mechanical operation.
A sensor 15, an ignition power capacitor 27, and an ignition capacitor for supplying a first ignition control signal to the first ignition means in response to the output of the first sensor and supplying an ignition current to the second ignition means. An airbag device comprising: a control unit that charges the vehicle. 3. The control means is responsive to the output of the first sensor, and the first ignition control signal and the second ignition means to be provided to the second ignition means in accordance with a predetermined condition after the generation of the first ignition control signal. It has a processing circuit for generating an ignition control signal, and a charging switching circuit 29 connected in series with the ignition power capacitor and conducted by the processing circuit. The first ignition means includes a first squib 21 and this first squib 21. A first switching circuit 24 connected in series to one squib and conducting in response to a first ignition control signal; the second ignition means is connected in series to the second squib 22 and the second squib; 3. The airbag device according to claim 2, further comprising a second switching circuit 35 that is turned on by the control signal for use. 4. A multi-stage deployment airbag control device including a plurality of stages of ignition means for deploying an airbag by energization, wherein ignition of an airbag deployed as a first stage is responsive to a first ignition control signal. First ignition means 23 for performing, second ignition means 41 for responsive to the second ignition control signal for igniting the airbag deployed as the second stage, and supplying an ignition current to the first and second ignition means. An ignition power source, a first sensor 14 for detecting an airbag deployment condition, and an ignition power source and the first and second ignition means.
A second sensor 15 which detects an airbag deployment condition and conducts by a mechanical operation, an ignition power capacitor 27, and a first ignition control signal to the first ignition means in response to the output of the first sensor. A control means for applying a second ignition control signal to the second ignition means according to a predetermined condition after the generation of the first ignition control signal, an energization detection means 44 for detecting energization of the first ignition means, and an energization detection means And a holding unit 45 that holds the energization detection output and derives a charging control signal to enable charging of the capacitor in response to the output of 1. 5. The control means is responsive to the output of the first sensor, and a processing circuit for generating first and second ignition control signals, and a charging switching circuit 29 connected in series to an ignition power capacitor. And the first ignition means includes a first squib 21 and a first switching circuit 24 connected in series with the first squib and conducting by a first ignition control signal, and the second ignition means is , A second squib 22 and a second switching circuit 35 connected in series to the second squib and conducting by a second ignition control signal. The energization detecting means 44 is interposed in series with the first igniting means. And a current detection element 51 for detecting a current, and an energization detection level discriminating circuit 52 for deriving an energization detection output when the ignition current of the current detection element is equal to or more than a predetermined value. Is a holding capacitor 56 that is charged by the output of the energization detection level discrimination circuit, and when the output of the holding capacitor is equal to or greater than a predetermined value, a charging control signal is supplied to the charging switching circuit to turn on the charging switching circuit. 5. The airbag apparatus according to claim 4, further comprising a charge control level discriminating circuit 59 that conducts. 6. The airbag device according to claim 3, wherein a current limiting circuit for setting an upper limit value of current is interposed in series with the first and second switching circuits. 7. A simultaneous ignition switching circuit 33 interposed between a second sensor and a second ignition means and electrically connected by a third ignition control signal, and a mode setting means for setting the first and second operation modes. Three
9, the processing circuit is responsive to the output of the mode setting means to generate the first and second ignition control signals at the staggered times in the first operation mode and the first operation mode in the second operation mode. 7. The third ignition control signal and the third ignition control signal are simultaneously generated.
The airbag device described.