JPH1134790A - Initiation element igniting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the initiation ignition of an initiation element of both a first start ignition set and a latter start ignition set by sufficient ignition energy, also prevent ignition failure of the initiation element according to a load damp surge. SOLUTION: In a power feed line extended from a battery power source, a first backup capacitor C1 is connected, also through a transistor Qb, a second backup capacitor C2 is connected, a plurality of initiation elements 12 are divided into a first/latter start ignition group, relating to a transistor Qi connected to the initiation element 12 of the first start ignition group, a first ignition command is generated, after a prescribed time, relating to a transistor Qi connected to the initiation element 12 of the latter start ignition group, a second ignition command is generated. The transistor Qb is opened simultaneously with the first ignition command, and closed after generating the second ignition command. In this way, the initiation element 12 ignited with a time difference can be surely initiation ignited with sufficient energy distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for igniting an element which can ignite with a sufficient ignition energy.

[0002]

2. Description of the Related Art An airbag system for protecting an occupant in the event of a vehicle collision is increasingly equipped with an airbag on both the driver's seat side and the passenger's seat side. A predetermined current, i.e., an ignition current, is applied to a detonating element called a squib by an impact sensor that closes a contact to cause detonation, and the airbag is instantly deployed by gas pressure or the like.

[0003] The conventional explosive element ignition device 1 shown in FIG.
Two explosive elements 2d for deploying airbags (not shown) incorporated in the driver's seat side and the passenger's seat side, respectively.
2a. The detonating elements 2d and 2a are grounded by transistors Qd and Qa which are turned on in response to an ignition command.
A series circuit of d, Qa and sneak-prevention diodes Dd, Da is connected in parallel to an impact sensing sensor 3 that senses an impact and closes, thereby forming an ignition circuit 10. This ignition circuit 10 is connected to a diode D0. It is connected to the battery power supply 4 via the power supply. It is determined by the CPU 6 whether or not the collision is to deploy the airbag when the vehicle receives an impact, and the transistors Qd and Qa are turned on by an ignition command issued by the CPU 6.

[0004] Reference numeral 7 denotes a booster circuit connected to the battery power supply 4 via a diode D1. The booster circuit 7 supplies the boosted output to a load circuit 5 via a diode D3, and shunts the auxiliary power supply line to the cathode of the diode D0. The connected backup capacitor C0 is charged. If the power supply line extending from the battery power supply 4 via the wire harness is cut off with the occurrence of a collision, the backup capacitor C0 is connected to the detonating elements 2d and 2a in the ignition circuit 10 in place of the battery power supply 4. Supply ignition current. That is, the backup capacitor C
With 0, the ignition current to the detonating elements 2d and 2a is backed up.

[0005]

When the wire harness extending from the battery power supply 4 is cut off due to the collision of the vehicle, the backup igniter 1 is replaced with the backup capacitor C0. It will function as an ignition current source for 2d and 2a. However, the driver's seat has a steering wheel, and the front passenger's seat has no steering wheel. There is a case where an ignition condition such as deployment slightly earlier is specified. In such a case, switching element Qd is replaced with switching element Qd.
a, most of the energy stored in the backup capacitor C0 when the switching element Qd is turned on is consumed for igniting the detonating element 2d, and the switching element Qd is delayed with respect to the switching element Qd. When Qa is turned on, there is a possibility that a sufficient supply of ignition energy to the detonating element 2a for the passenger side airbag cannot be guaranteed, and there is a problem that the deployment of the airbag may fail. .

In addition, the battery power supply 4
If the wire harness connecting the power supply and the boost circuit 7 or the wire harness connecting the battery power supply 4 and another load circuit (not shown) is cut off, the output voltage of the battery power supply 4 sharply decreases with the rapid reduction of the load. There was a case where a load dump surge was generated. It is known that such a load dump surge appears with a peak voltage whose peak voltage reaches 70 V as shown in FIG. 4A, for example, and that its decay time constant reaches 200 ms. -Generally, if the airbag does not deploy as soon as possible within this time constant at the latest at the time of the collision, the protection of the occupants will not be obvious, and on average, several tens of meters immediately after the collision occurs
The ignition command issued from the CPU 6 to the transistors Qd and Qa for s is usually sufficiently included in the load dump surge period as shown in FIG. For this reason, an excessively large current flows into the transistors Qd and Qa due to an excessive voltage caused by the load dump surge, and the transistors Qd and Qa may be destroyed instantaneously. As a result, the airbag cannot be deployed. There was a problem that occupant protection could end in misfire.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. In the present invention, both the starting element and the starting element of the starting and igniting group can be ignited with sufficient ignition energy, and the starting element accompanying the load dump surge is provided. The purpose of the present invention is to prevent the failure of the ignition of the engine.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a shock sensor connected to a power supply line extending from a battery power supply and sensing and closing a shock, and a downstream side of the shock sensor. Each of the detonating elements is connected to a plurality of branch feeder lines that are branched in parallel, and is supplied with an ignition current and is detonated and ignited.Then, each of the detonating elements is connected in series and closed in response to an external ignition command to ignite. A switching element for supplying a current, a first backup power supply branched and connected to the power supply path, and charged by the battery power supply; a second backup power supply connected to the power supply path via switching means; Is divided into a starting ignition group and a late ignition group, and a first ignition command is issued to a switching element connected to the ignition element of the starting ignition group for a predetermined time. After a short time, a second ignition command is issued to the switching element connected to the detonating element of the post-ignition group, and the switching means is opened at the latest until the first ignition command is issued, and the second ignition command is issued. And ignition control means for closing after issuing an ignition command.

The power supply system further includes a constant voltage circuit disposed on an upstream power supply line of the first backup power supply to control an output voltage of the battery power supply to a constant voltage, or connected to the switching element, It is characterized by further comprising a constant current circuit for controlling the ignition current to a constant current.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic circuit configuration diagram showing one embodiment of the detonating element ignition device of the present invention, and FIG. 2 is a signal waveform diagram of each part of the circuit shown in FIG.

The explosive element ignition device 11 shown in FIG. 1 is not only an airbag for protecting the occupants in the driver's seat and the passenger's seat, but also an occupant restraint such as a pretensioner for applying a pretension to a seat belt for each occupant. Also, a plurality of, for example, four ignition systems are connected in parallel in the ignition circuit 21 via the wraparound diode D. However, since the basic circuit configuration is the same for all ignition sequences except for the ignition timing, the following description focuses on the-ignition sequence.

[0012] Each ignition sequence in the ignition circuit 21 detects a sneak-prevention diode D, a current limiting resistor R, a detonating element 12, a transistor Qi, and its source resistor Rs in response to an impact sensor 13 that senses an impact and closes. Are connected in series. The transistor Qi, which is an N-channel FET grounded via the source resistance Rs, receives the output of the differential amplifier 14 operating so that the difference voltage between the source voltage and the set voltage Vir becomes zero via the gate resistance Rg. Has a constant current control function of keeping the current flowing through the source resistance Rs constant by keeping the source voltage at the set voltage Vir. That is, in the present embodiment, the transistor Q
i, the source resistance Rs, and the differential amplifier 14 constitute a main part of the constant current circuit 15. Further, in order to cause an ignition current to flow through the transistor Qi in response to an ignition command from the CPU 30, the collector of the transistor Q1 that switches from the conductive state to the cutoff state in response to the ignition command issued by the CPU 30 is connected to the gate of the transistor Qi. The emitter of Q1 is grounded. R1 is a base-emitter resistance, R2 is a base resistance, and R3 is a pull-up resistance for lifting the ignition command input terminal to a + 5V power supply Vcc. The current limiting resistor R connected between the wraparound diode D and the detonating element 12 is connected between the detonating element 12 and the drain of the transistor Qi or the transistor Qi.
When the ground itself is short-circuited, the detonating element 12
Works to limit the current flowing through to the ignition current or less. For this reason, even if the ground short-circuit failure occurs in one of the ignition sequences, it is possible to supply a sufficient ignition current to the other ignition sequences.

The detonating elements 12 included in each of the four ignition sequences classify the driver's seat side into a starting ignition group and the passenger seat side into a late ignition group according to the timing of the ignition timing. It is. That is, the transistor Qi connected to the detonating element 12 of the first ignition set and the transistor Qi connected to the detonating element 12 of the second ignition set have a time difference in the conduction timing, and the transistor Q1 is quickly activated by the ignition command from the CPU 30. The transistor Qi of the set that has shifted to the cutoff state conducts prior to the transistor Qi of the remaining set, and the ignition current is supplied to the corresponding detonating element 12 in advance.

A main power supply path from the battery power supply 4 to the ignition circuit 21 extends through a diode D0, and a constant voltage circuit 22 is connected to the main power supply path. Further, a first backup capacitor C1 as a first backup power supply is branched and connected to a power supply path between the constant voltage circuit 22 and the ignition circuit 21. The constant voltage circuit 22 has a configuration in which a drain voltage is fed back to the gate of a transistor Qv composed of a P-channel FET via a differential amplifier 22a, and the drain voltage of the transistor Qv is set to the differential amplifier 22a. The set voltage Vvr can be kept constant. That is, the gate voltage of the transistor Qv is variably controlled so that the error voltage between the drain voltage of the transistor Qv and the set voltage Vvr (here, 15 V, for example) becomes zero, and the drain voltage of the transistor Qv is controlled at a constant voltage. Note that the source voltage of the transistor Qv connected downstream of the junction of the power supply lines extending from the anodes of the diodes D0 and D2 is usually the output voltage of the booster circuit 23 that boosts the output voltage of the battery power supply 4, Since the set voltage Vvr is lower than the output voltage, the constant voltage circuit 22 can always perform the constant voltage operation continuously. Further, the first backup capacitor C1 is:
Since the battery is charged via the constant voltage circuit 22, the charging voltage is always kept at, for example, 15V-constant. For this reason, the withstand voltage of a value slightly larger than the output voltage of the constant voltage
A withstand voltage of about V is sufficient, and when compared with a second backup capacitor C2 having a withstand voltage of 25 V or more to be described later, a large-capacity electrolytic capacitor can be procured at a low cost because the withstand voltage is kept low.

On the other hand, a sub power supply line extends from the battery power supply 4 via a diode D1, and a booster circuit 23 is connected to the sub power supply line. The booster circuit 23 boosts the battery output voltage (12 to 15 V) to a predetermined voltage of 18 to 24 V, and supplies the boosted output to the load circuit 5 via the diode D3. Also, this booster circuit 23
A second backup capacitor C2 constituting a second backup power supply and a transistor Qb as switching means are branched and connected to the load power supply line. The second backup capacitor C2 has a withstand voltage of 25 V or more, and, together with the first backup capacitor C1, guarantees backup of the battery power supply 4 as an alternative power supply. The transistor Qb has its drain connected to the main power supply line via a diode D2,
Here, the conductive state is maintained until the CPU 30 issues the first ignition command, the state is temporarily switched to the non-conductive state with a cutoff command issued at the same time as the first ignition command, and further, the state is activated after the second ignition command. Conduction in response to the conduction command issued,
It functions to guarantee ignition energy to the detonating element 12 of the later ignition group.

Here, when a vehicle collision occurs, FIG.
As shown in (A), the impact sensor 3 is closed, and subsequently, the CPU 30 that determines from the magnitude of the impact force and the elapsed time that it is a collision to activate the airbag or the pretensioner is fired. Issue a command. However, it has already been mentioned that this ignition command is issued with a slight time difference between the first ignition group and the second ignition group. Accordingly, the transistor Q1 of the starting ignition group which has received the first ignition command shown in FIG. 2 (B) as a base is first switched to the cut-off state, and the transistor Q1 whose gate is released from the ground state.
i conducts. However, at the same time as the first ignition command, the CPU
Since 30 issues a cutoff command to transistor Qb, constant voltage circuit 22 is supplied with power only through the main power supply line. Therefore, at this point, if the collision does not affect the wire harness extending from the battery power supply 4 and no load dump surge occurs, the power is supplied from the battery power supply 4 and the first backup capacitor C1. The detonating element 12 of the starting ignition group is detonated by the ignition current, and the airbag and the pretensioner on the driver's seat side are activated first.

Next, as shown in FIG. 2C, a second ignition command is output from the CPU 30 slightly after the first ignition command. For this reason, after receiving the second ignition command, the transistor Q1 of the ignition group is switched to the cut-off state, and the transistor Qi whose gate is released from the ground state is turned off.
Becomes conductive. At this time, even if the impact of the collision does not reach the wire harness extending from the battery power supply 4 and no load dump surge occurs, the detonating element 12 of the later-ignition set is also connected to the battery power supply 4 and the second power supply. The ignition is initiated by the ignition current supplied from the first backup capacitor C1. Thereby, the airbag and the pretensioner on the passenger seat side are operated.

If the wire harness connecting the battery power supply 4 and the constant voltage circuit 22 is cut off with the occurrence of the collision, the explosion element 12 of the first ignition set and the explosion element 12 of the second ignition set are not the battery power supply 4. The first backup capacitor C1 and the second backup capacitor C2 must be used as ignition energy sources. However, as shown in FIG. 2D, the transistor Qb connecting the second backup capacitor C2 to the main power supply line is in a cut-off state in response to a cut-off command issued at the same time as the first ignition command. Since the conduction does not take place until a conduction command output later than the second ignition command is received, the ignition element 12 of the starting ignition set that is supplied with the ignition current by the transistor Qi that has been rendered conductive by the first ignition command is shown in FIG. As shown in FIG. 2 (E), even if most of the energy stored in the first backup capacitor C1 has been consumed, the second backup capacitor C2 will not be able to operate as shown in FIG. 2 (F). As described above, a sufficient ignition current can be supplied to the detonating element 12 of the later-ignition set after the detonation, so that the detonation of the detonation element 12 of the later-ignition set can be performed with a sufficient ignition energy. It is possible to guarantee with a.

Also, a load dump surge may occur simultaneously with the disconnection of the wire harness, and an overvoltage may be applied to the diode D0. However, as described above, the constant voltage circuit 22 keeps the applied voltage of the ignition circuit 21 at a constant voltage, and the constant current circuit 15 limits the current flowing through each ignition sequence to a constant ignition current. The transistor Qi does not blow.
That is, the influence of the load dump surge voltage having a peak value of 70 V does not directly affect the ignition circuit 21, and the flow of the ignition current exceeding the allowable upper limit (for example, 9 A) to the transistor Q is prevented. Therefore, for example, the inconvenience that the transistor Qi is destroyed before sufficient ignition energy is applied to the detonating element 12 and the airbag or the pretensioner ends unexpectedly is eliminated. Also, if a collision occurs, the constant current circuit 1
Even if 5 is short-circuited, the constant voltage circuit 22 controls the voltage applied to the ignition circuit 21 to a predetermined low voltage, so that an excessive current that would blow the shock sensor 13 and the transistor Qi is generated. It does not flow, and the detonating element 12 can be reliably detonated and ignited.

The ignition circuit 21 includes the shock sensor 1
3 and the detonating element 12, a current limiting resistor R for limiting the current flowing through the detonating element 12 to an ignition current or less when the transistor Qi is short-circuited to ground is sufficient for other ignition series. It is possible to supply an appropriate ignition current. Further, in a case where the downstream end side of the detonating element 12 is short-circuited to the ground and the impact sensing sensor 13 is closed even though the CPU 30 has not made a collision determination and issued an ignition command. However, only a current less than the ignition current flows into the detonating element 12, and it is possible to prevent accidental explosion of the detonating element 12.

In the above embodiment, the case where the airbag or the pretensioner on the driver's seat side is actuated before the airbag or the pretensioner on the passenger's seat side is taken as an example, but these relations are reversed. Alternatively, it is also possible to adopt a configuration in which the operating time differs between the airbag and the pretensioner. Also, the transistor Qb
Although the case where the PU 30 is set to the cut-off state by the cut-off command output at the same time as the first ignition command is taken as an example, a configuration in which the PU 30 is switched to the cut-off state at the same time as the closing of the impact sensor 13 may be adopted.

[0022]

As described above, according to the present invention,
A first backup power supply is connected to a power supply line extending from a battery power supply, and a second backup power supply is connected via a switching unit, and the plurality of detonating elements are divided into a first ignition group and a second ignition group. A first ignition command is issued to the switching element connected to the detonating element, and a second ignition command is issued to the switching element connected to the detonating element of the post-ignition group after a predetermined time has elapsed. Since the first ignition command is issued before the first ignition command is issued and the second ignition command is issued and then closed, the switching means for connecting the second backup power supply to the power supply line is provided with 2
That the ignition element of the starting ignition set has consumed most of the energy stored in the first backup power supply by the switching element which has been turned on by the first ignition instruction. Also, the second backup power supply can supply an ignition current after the detonating element of the later-ignition set has detonated and fired, and can guarantee the detonation of the detonating element of the later-ignition set with sufficient ignition energy. When the operating conditions of airbags and pretensioners are switched due to vehicle construction reasons such as a large movable space between a certain driver's seat side and a passenger's seat side without a steering wheel, a reliable firing of the detonating element is guaranteed. It has excellent effects such as being able to perform.

Further, according to the present invention, a constant voltage circuit is provided in the power supply line on the upstream side of the first backup power supply to control the output voltage of the battery power supply to a constant voltage. Even if the wire harness that connects the load circuit other than the ignition element ignition system is cut and a load dump surge that starts with a sudden load reduction occurs, the constant voltage circuit provided in the power supply path to the The voltage applied to the power supply element can be controlled to be equal to or less than the allowable voltage, thereby suppressing the overvoltage accompanying the load dump surge to be equal to or less than the allowable voltage, preventing the overcurrent from flowing into the detonating element, and Eliminates the disadvantage that circuit components such as sensing sensors and switching elements are destroyed before applying sufficient ignition energy to the detonating element,
The detonating element can be reliably fired and ignited, and the constant voltage circuit suppresses the ignition current to an appropriate current, so that the withstand voltage and capacity of the first backup power supply can be kept low and cost can be reduced. It has excellent effects.

Further, since a constant current circuit is connected to the switching element to control the ignition current to a constant current, the voltage applied to the ignition circuit by the constant voltage circuit is maintained at a constant voltage. Since the current flowing in the ignition circuit is limited to a constant current by the constant current circuit, the overvoltage accompanying the load dump surge is suppressed to the allowable voltage or less and the allowable current or less, so that the overcurrent does not flow into the ignition circuit,
Therefore, circuit components such as an impact sensor and a switching element in the ignition circuit are not destroyed before applying sufficient ignition energy to the detonating element, and the detonating element can be reliably detonated and fired. In addition, since the ignition current is suppressed by the constant voltage circuit and the constant current circuit, it is possible to reduce the withstand voltage and capacity of the second backup power supply, thereby reducing costs.

[Brief description of the drawings]

FIG. 1 is a schematic circuit configuration diagram showing an embodiment of a detonating element ignition device of the present invention.

FIG. 2 is a signal waveform diagram of each section of the circuit shown in FIG.

FIG. 3 is a schematic circuit diagram illustrating an example of a conventional explosive element ignition device.

4 is a signal waveform diagram of each section of the circuit shown in FIG.

[Explanation of symbols]

4 Battery Power Supply 5 Load Circuit 11 Explosive Element Ignition Device 12 Explosive Element 13 Shock Sensing Sensor 14, 22a Differential Amplifier 15 Constant Current Circuit 21 Ignition Circuit 22 Constant Voltage Circuit 23 Boost Circuit 30 CPU Qi Switching Element (Transistor) Qb Switching Means Transistor) C1 First backup power supply (first backup capacitor) C2 Second backup power supply (second backup capacitor)

Claims (3)

[Claims] 1. An impact sensor connected to a power supply line extending from a battery power supply and sensing and closing an impact, and connected to a plurality of branch power supply lines branching in parallel downstream of the impact sensor and igniting. A detonating element that is energized and ignited by a current, a switching element that is connected in series to each of the detonating elements, closes in response to an external ignition command, and energizes the ignition current, and is branched and connected to the power supply path; A first backup power supply charged by the battery power supply, a second backup power supply connected to the power supply line via switching means, and the plurality of detonating elements are divided into a first ignition group and a second ignition group, A first ignition command is issued to a switching element connected to the detonating element of the first ignition group, and after a predetermined time, a switch connected to the detonating element of the second ignition group. Ignition control means for issuing a second ignition command to the switching element, opening the switching means at the latest before issuing the first ignition command, and closing the switching means after issuing the second ignition command. A detonating element ignition device comprising: 2. The detonating device according to claim 1, further comprising a constant voltage circuit disposed on an upstream power supply line of the first backup power source and controlling an output voltage of the battery power source to a constant voltage. Element ignition device. 3. The ignition element ignition device according to claim 2, further comprising a constant current circuit connected to said switching element and controlling said ignition current to a constant current.