JPH10315902A - Power supply device for occupant protection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device which can correspond to general purpose even if the standards of an on-vehicle power source are different and surely operates occupant protection system by providing a logic circuit power source for operating a collision deciding circuit for judging whether an electric current is to be applied to a firing device or not and a current supply circuit. SOLUTION: An electric current from a current supply circuit 2 is let flow in a third terminal 23 with priority by a diode 3 disposed between a resistance r2 and the third terminal 23, so that the operation of Tr1 and Tr2 is stabilized by a capacitor 8. A power supply device 1 is formed by a diode 6 with a potential drop of about 1.1 V at maximum and a transistor 10 with potential difference of about 1.5 V, and when the operation of a transistor 10 is saturated by a current from the power supply circuit 2, voltage of about 5.4 V to a terminal 17 can be output in respect to voltage impression of 8 V to a power supply input terminal 5. Accordingly, logic circuit power supply 12 can output d.c. voltage of +5 V required for surely operating a collision judging circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for an occupant protection system mounted on a vehicle to protect the occupant in the event of a vehicle collision.

[0002]

2. Description of the Related Art In recent years, vehicles such as passenger cars and trucks include:
2. Description of the Related Art An occupant protection system called an airbag system is mounted to protect an occupant from an impact generated at the time of a vehicle collision. The airbag system includes a collision sensor for detecting a vehicle collision, an ignition device called a squib that operates to ignite the explosive by energizing heating, and an instantaneous blast caused by the ignition of the explosive based on the operation of the squib. An airbag that inflates and protects an occupant, and a collision determination circuit that operates to energize the squib based on a signal from the collision sensor.

[0003] When a collision occurs in the vehicle, the collision judging circuit comprising a logic circuit including a microprocessor activates the airbag based on a signal output from the collision sensor and indicating a collision situation. It is determined whether the situation should be caused. When the collision determination circuit determines that it is a situation to operate the airbag, the collision determination circuit outputs a signal corresponding to an operation command to a power supply circuit for operating the squib. As a result, a constant voltage is supplied to the squib to generate energized heating, and the explosive is ignited to operate the airbag.

Accordingly, in order to operate the airbag system, a power supply circuit for supplying a constant voltage to the squib and a power supply for a logic circuit for operating the collision determination circuit including a logic circuit are provided. Is necessary. A power supply for operating these airbag systems is a circuit unit that can convert power supplied from an onboard power supply originally provided in a vehicle so as to satisfy a power supply specification required for operation of the airbag system. With such a configuration, it can be operated by the on-vehicle power supply.

[0005]

By the way, the above-mentioned on-vehicle power supplies have different specifications such as output voltage between vehicles of the same type having different sizes and the like (small trucks and large trucks). Therefore, a power supply device for an airbag system has been prepared for each output standard of a different output of each vehicle-mounted power supply so as to be able to cope with a difference in the standard of the vehicle-mounted power supply. However, if it is necessary to prepare a power supply for the airbag system corresponding to each type of on-board power supply, it is necessary to separately prepare circuit components for configuring the power supply. It is necessary to prepare various types of parts, and the parts management becomes complicated.

Also, in assembling the power supply unit, it is necessary to prepare a plurality of types of processes corresponding to differences in work contents based on differences in the types of parts, resulting in complicated production management. Will be invited. Therefore, if it is necessary to prepare various types of power supply devices for the airbag system in accordance with the difference in the standard of the vehicle-mounted power supply, the work required to manufacture the various types of power supply devices as a whole becomes complicated, and the production cost is reduced. This will lead to an increase.

On the other hand, in order to operate the collision judging circuit so as to appropriately judge the situation of the collision of the vehicle and to operate the squib so as to fire at an appropriate time, the squib is operated properly. Therefore, it is necessary to reliably output required power from the power supply device, and it is necessary to reliably operate each circuit element constituting the power supply device with required characteristics.

Accordingly, the present invention is a power supply device of an occupant protection system mounted on a vehicle to protect an occupant in the event of a vehicle collision, and is generally applicable to a case where the standard of an onboard power supply is different. The present invention relates to an apparatus capable of reliably operating an occupant protection system.

[0009]

According to a first aspect of the present invention, there is provided an ignition device (1) which is operated by a vehicle-mounted power supply and is provided in an occupant protection system.
6) A power supply device (1) for an occupant protection system for supplying power to the occupant protection system, wherein a DC voltage having a predetermined voltage value is supplied to an input terminal (17) supplied with a DC voltage from the vehicle-mounted power supply and the ignition device (16). A booster circuit (11) having an output terminal (18) for outputting a voltage; a voltage storage capacitor (14) provided to store electric charges on the output terminal (18) side of the booster circuit (11); A resistor (r2) is connected to the first terminal (21) connected to the power supply, the second terminal (22) connected to the input terminal (17) of the booster circuit (11), and the first terminal (21). Darlington transistor (10) having a third terminal (23) connected via
A collision judging circuit (13) for judging whether or not the ignition device (16) should be energized; and a booster circuit (1) for the second terminal (22) of the Darlington transistor (10).
A logic circuit power supply (12) that is connected in parallel with the input terminal (17) of 1) and operates the collision determination circuit (13).
And an output terminal (1) of the booster circuit (11).
A power supply device (1) for an occupant protection system, comprising a current supply circuit (2) for connecting the third terminal (23) of the Darlington transistor (10) with a third terminal (23) via a resistor (R). ).

[0010] According to the power supply device described above, a plurality of vehicle-mounted power supplies having different voltage standards, for example, one mounted on a truck.
A single power supply unit can be used for a plurality of on-vehicle power supplies having different voltage values such as 2V and 24V. That is, the power supply device can reliably operate as an operation power supply necessary for operating the ignition device provided in the occupant protection system with respect to a plurality of vehicle power supplies having different voltage standards. As described above, the conventional power supply device for the occupant protection system is designed to cope with a plurality of on-board power supplies having different voltage standards with different configurations, but from the viewpoint of consolidating components and the like. It is desired to provide a power supply device that can be shared by a plurality of types of vehicle-mounted power supplies.

Here, in the case where a single power supply capable of supporting a plurality of types of vehicle-mounted power supplies is to be realized, considering the upper limit of the allowable power of each type of power supply, the vehicle-mounted power supply having a large voltage value is considered. It is conceivable to divert a power supply device that can cope with the above into an in-vehicle power supply having a small voltage value. However, when a power supply device capable of supporting a vehicle-mounted power supply having a large voltage value is connected to a vehicle-mounted power supply having a small voltage value, the ignition device provided in the occupant protection system may not always be operated.

This is because the operation of the Darlington transistor cannot be saturated if the voltage applied to the Darlington transistor provided to protect the booster circuit and the power supply for the logic circuit provided in the power supply device is small. This may result in a case where the output voltage cannot be increased sufficiently, thereby causing a case where the necessary voltage is not supplied to the logic circuit power supply and the collision determination circuit cannot be operated.

[0013] On the other hand, according to the power supply device of the present invention, even when the power supply device is connected to a vehicle-mounted power supply having a relatively small voltage value, the operation of the Darlington transistor can be saturated. The collision judging circuit can be reliably operated by outputting a sufficient voltage from the Darlington transistor. That is, according to the power supply device of the present invention, by providing the current supply circuit that connects the output side of the booster circuit and the third terminal of the Darlington transistor, the output side of the booster circuit connects the output terminal of the booster circuit to the third terminal of the Darlington transistor. An operating current can be supplied. Accordingly, even when the voltage input to the power supply device is relatively small and only a small voltage that cannot saturate the operation to the first terminal of the Darlington transistor is applied, the operation of the Darlington transistor can be saturated. As a result, a sufficient voltage required for the logic circuit power supply is output from the second terminal of the Darlington transistor, so that the collision determination circuit can be operated.

[0014] Regarding the generation of energized heating in the ignition device of the occupant protection system, since the voltage can be increased to a predetermined voltage value required for the operation of the ignition device by the booster circuit, the ignition device is connected to the power supply device. It does not matter if the onboard power supply is of a low voltage standard.

According to a second aspect of the present invention, a current which is connected between the third terminal (23) and the first terminal (21) of the Darlington transistor (10) and conducts the current supply circuit (2) is provided. The power supply device for an occupant protection system according to claim 1, further comprising a first diode (3) reversely connected to the third terminal (23) so as to preferentially guide the third terminal (23). (1). The first diode can prevent a current supplied from the current supply circuit from conducting to the first terminal side. This allows the current supplied from the current supply circuit to flow into the third terminal preferentially, so that more current can flow into the third terminal of the Darlington transistor, The operation of the transistor can be more easily saturated.

The invention according to claim 3 is provided between the voltage storage capacitor (14) and an output terminal of the booster circuit (11) to which the current supply circuit (2) is connected. The power supply device (1) for an occupant protection system according to claim 1 or 2, further comprising a second diode (4) reversely connected to the storage capacitor (14). On the output terminal side of the booster circuit, the voltage storage capacitor for storing electric charge is provided, and even if a situation in which no voltage is supplied to the booster circuit due to damage of a vehicle-mounted power supply or the like occurs, The ignition device can be energized by the voltage held in the storage capacitor. In the invention according to the present claim, a second diode is connected between the voltage storage capacitor and an output terminal of the booster circuit to which the current supply circuit is connected, with respect to the voltage storage capacitor. Connected to be connected. The second diode can prevent the charge stored in the voltage storage capacitor from flowing out through the current supply circuit. This prevents unnecessary depletion of the charge stored in the voltage storage capacitor, so if the voltage is not supplied to the booster circuit due to damage to the vehicle power supply, etc., the voltage is stored in the voltage storage capacitor. The ignition device can be immediately energized by the applied voltage, and the occupant protection system can be reliably operated.

According to a fourth aspect of the present invention, the power supply for the occupant protection system is a power supply for operating an occupant protection system mounted on a truck. Power supply device for an occupant protection system. Trucks are equipped with in-vehicle power supplies having different voltage standards of 12V and 24V. According to the power supply device, the occupant protection system mounted on the truck can be reliably operated by a single power supply device. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power supply device for an occupant protection system according to the present invention (hereinafter simply referred to as "power supply device") will be described with reference to FIGS. FIG.
FIG. 1 shows a schematic circuit configuration of a power supply device 1 for operating an occupant protection system mounted on a truck as an example of a power supply device of the present invention. The power supply device 1 converts the electric power supplied from the vehicle-mounted power supply into a squib 1
6 is formed to an operating voltage at which the device 6 can operate. Here, the specification of the vehicle-mounted power supply will be described with reference to an example of the case of 12V and 24V. In the case of the 12V standard, the output from the vehicle-mounted power supply varies in the range of 8V to 16V, In the case of, 16V-3
Variation occurs in the range of 2V.

A power supply input terminal 5 provided in the power supply device 1 is connected to a vehicle-mounted power supply of a truck, and receives a DC voltage composed of a positive voltage output from the vehicle-mounted power supply. Power input terminal 5
, A Darlington transistor 10 is connected in series. Here, this Darlington transistor 10
A transistor configured by a Darlington connection of two transistors Tr1 and Tr2 is used.

In the Darlington transistor 10, a collector terminal of Tr1 and a collector terminal of Tr2 are connected in parallel to a first terminal 21 connected in series to the power input terminal 5, and a base terminal of Tr1 and Tr2 And the emitter terminal of Tr1 is connected to the input terminal 17 of the booster circuit 11 as the second terminal 22. Then, the base terminal of Tr2 forms the third terminal 23. Further, a resistor r1 is connected between the base terminal and the emitter terminal of Tr2,
By forming a constant potential difference between the base terminal and the emitter terminal of the transistor Tr2, the base current of the transistor Tr2 can be stabilized. In the example shown here, the Darlington transistor 10 has a multiplication factor of a current flowing between the first terminal 21 and the second terminal 22 to a current value input to the third terminal 23 of about 600 to 1200. Is used.

The first terminal 21 and the third terminal 23 are connected via a resistor r2 so that a constant potential difference can be formed between the base terminal and the collector terminal of Tr2. In the example shown here, the resistance value is 750Ω as r2.
Is used. In this example, the diode 3 as the first diode is provided between the resistor r2 and the third terminal 23 so as to be reversely connected to the third terminal 23. The diode 3 allows the current supplied from the current supply circuit 2 to flow into the third terminal 23 preferentially.

Further, the potential of the first terminal 21 and the third terminal 23 can be stabilized by the capacitor 8 provided between the diode 3 and the resistor r2, and Tr1 and Tr2
Operation can be stabilized. Also, the third terminal 23
Between the third terminal 2 and the ground terminal.
3 is connected in reverse. As a result, even if a so-called load dump surge whose peak voltage value reaches about 300 V is applied instantaneously, the base voltage of Tr2 is fixed to the Zener voltage of Zener diode 9 and Tr1 is fixed.
The second terminal 22 does not become higher than the Zener voltage, and the booster circuit 11 and the logic circuit power supply 12 can be protected from excessive input.

In the example shown here, the Zener diode 9 has a so-called Zener voltage of +22 V. When a DC voltage of +22 V or more is applied, the portion of +22 V or more is r2. Since the voltage drop is eliminated by the voltage drop, the booster circuit 11 and the power supply 12 for the logic circuit
DC voltage of +22 V or more is not applied to the power supply.

Between the power input terminal 5 and the first terminal 21 of the Darlington transistor 10, a protection diode 6 is connected in series with the power input terminal 5 in the forward direction. Accordingly, even when a negative voltage is applied to the power supply input terminal 5 due to a wrong connection direction of a battery as a power source of the vehicle-mounted power supply or the like, the power supply device 1
Is protected.

The input terminal of the booster circuit 11 and the input terminal of the logic circuit power supply 12 are connected in parallel to the second terminal 22 of the Darlington transistor 10 via the terminal 17. The booster circuit 11 is for stably supplying a constant DC voltage so as to energize and heat the squib 16. When a positive DC voltage is input from the input terminal 17 to the input side, the booster circuit 11 outputs from the output side. A constant DC voltage is output to the output terminal 18. In this example, +24 V is output to the output terminal 18. Even if the voltage applied to the input terminal 17 is less than +24 V, the booster circuit 11 is internally provided with a boost DC-DC converter, so that the +24 V DC voltage is applied to the output terminal 18. Can be output.

The logic circuit power supply 12 is a power supply for operating the collision judging circuit 13. The power supply 12 for the logic circuit is designed to operate the collision judging circuit 13 constituted by logic circuit elements.
It is required that a DC voltage of +5 V can be reliably output to the collision determination circuit 13.

The output terminal 18 of the booster circuit 11 and the third terminal 23 are connected via a resistor R.
The current supply circuit 2 is formed between the terminal 8 and the terminal 23. In this example, a resistor having a resistance value of 1.6 KΩ is used as the resistor R, and a current determined by the resistance value and the potential of the terminal 18 flows into the third terminal 23. Then, the current flowing into the third terminal 23 acts as an increase in the base current of Tr2. Here, the resistance value of the resistor R is determined based on the amount of current to be supplied from the current supply circuit 2 as an increase of the base current of Tr2 and the capacity of the current that can be output from the booster circuit 11. Note that the amount of current to be supplied from the current supply circuit 2 is obtained based on the amount of base current of the Tr2 necessary to saturate the operation of the Darlington transistor 10 described later.

On the output side of the booster circuit 11, a capacitor 14 as a voltage storage capacitor for storing electric charges is connected between the capacitor 14 and a ground terminal. Due to the capacitor 14, even if the voltage is not supplied to the power supply terminal 5 and the voltage cannot be output from the booster circuit 11 due to the damage of the vehicle-mounted power supply or the like, the squib 16 is heated by the voltage held in the capacitor 14. It can be done. The diode 4 as a second diode is connected between the terminal 18 and the capacitor 14 so as to be reversely connected to the capacitor 14.
The diode 4 can prevent the charge stored in the capacitor 14 from flowing out through the current supply circuit 2.

Although not shown in FIG. 1, the voltage storage capacitor is also provided on the input side of the power supply 12 for the logic circuit. Thus, when a situation occurs in which no voltage is supplied to the power supply terminal 5 due to damage to the vehicle-mounted power supply or the like, the logic circuit power supply 12 supplies the collision determination circuit 13.
And a DC voltage of +5 V can be output.

According to the power supply device 1 configured as described above, the voltage supplied from the vehicle-mounted power supply via the input terminal 5 can be formed into a stable DC voltage having a predetermined voltage value. The operating voltage required to operate the squib 16 can be supplied.

The collision judging circuit 13 is connected to a collision sensor (not shown). The collision judging circuit 13 judges a collision situation based on acceleration or the like acting upon a collision of the vehicle detected by the sensor, and protects an occupant from an impact. It is determined whether or not the airbag should be operated. When the collision determination circuit 13 determines that the airbag should be activated, the collision determination circuit 13 turns on the transistor 15 provided in the power supply device 1. As a result, the operating voltage is applied to the squib 16, and the squib 16 is energized and heated, and the explosive (not shown) causes the airbag to expand.

Next, the operation of the power supply device 1 will be described below. (1) Operation Example 1 When the standard of the vehicle-mounted power supply is 24 V, the upper limit of the variation of the voltage output from the vehicle-mounted power supply is 32 V. The case where 32 V is applied to the input terminal 5 of the power supply device 1 will be described. . When a voltage of 32 V is applied to the power input terminal 5, the Zener voltage 22 of the Zener diode 9 is applied from the second terminal 22 of the Darlington transistor 10 to the terminal 17.
A voltage of 23V, which is a voltage slightly higher than V, is output.
As a result, the logic circuit power supply 12 is necessary for the collision determination circuit 13 to operate reliably +5.
V DC voltage is output. In addition, the booster circuit 11 is necessary to cause the squib 16 to be energized and heated.
Outputs 4V DC voltage.

(2) Operation Example 2 When the standard of the vehicle-mounted power supply is 12 V, the lower limit of the variation of the voltage output from the vehicle-mounted power supply is 8 V, but when 8 V is applied to the input terminal 5 of the power supply device 1. Will be described. The operation of the Darlington transistor 10 cannot be saturated only by application of the voltage of 8 V supplied to the power input terminal 5, and the power supply 1
2 cannot output the required voltage. Regarding the saturation of the operation of this transistor, FIG.
Description will be made based on (b). FIG. 2A shows the characteristics of the collector current with respect to the base current of the transistor, and FIG. 2B is a diagram schematically showing each terminal of the transistor, voltage and current. Darlington Transistor 1
When the Tr1, Tr2, such as NPN-type transistors constituting the 0 is operated by the base ground architecture, a collector current i _c which conducts from collector terminal to the emitter terminal with the increase in the base current i _b flowing from the base terminal to increase A phenomenon corresponding to a decrease in the impedance between the collector terminal and the emitter terminal occurs. The collector - with a decrease in the impedance between the emitter potential v _e of the emitter terminal is raised with respect to the potential v _c applied to the collector terminal, the collector - potential difference v _ce between the emitter is reduced.

[0034] Then, the increase of the collector current i _c with respect to the increase in the base current i _b is show saturation, increase in the potential v _e of the emitter terminal, i.e., the collector - reduction of the potential difference v _ce between the emitter also arrives to saturated As a result, the operation of the transistor is saturated. That is, the potential difference v _ce decreases with increase in the base current i _b, when reaching the operation of the transistor is saturated, leading to a specific constant potential difference to each transistor.

Here, the power supply device 1 according to the present invention has a configuration in which the current is supplied to the third terminal 23 of the transistor 10 by the current supply circuit 2, so that the operation of the transistor 10 can be easily saturated. That is, the current flowing from the current supply circuit 2 into the third terminal 23 flows into Tr2 as an increase in the base current. Then, the emitter current that is output by amplifying the base current of Tr2 flows in as the base current of Tr1. The operation of Tr1 can easily be saturated by the inflow of the base current having a sufficient current amount. In the power supply circuit 1 shown in this example, when the diode 6 has a potential drop of about 1.1 V at the maximum and the transistor 10 has a potential difference _Vce of about 1.5 V when the operation is saturated, When the operation of the transistor 10 is saturated by the supply of the current by the current supply circuit 2, the voltage of 5.4 is applied to the terminal 17 in response to the application of the voltage of 8 V to the power input terminal 5.
It is possible to output a voltage of about V. Therefore, the logic circuit power supply 12 supplies the collision determination circuit 13 with:
It is possible to output a DC voltage of +5 V, which is necessary for reliably operating this.

[0036]

As described above, the first aspect of the present invention is as follows.
The described invention is applicable to a plurality of vehicle power supplies having different standards.
There is an effect that the operating power required for reliably operating the ignition device provided in the occupant protection system can be provided by a single power supply device. This makes it possible to consolidate the types of components for constituting the power supply device, thereby facilitating component management, simplifying the process of manufacturing the power supply device, and improving production management. The effect that it can be made easy is produced.

The invention described in claim 2 has an effect that the operation of the Darlington transistor can be more easily saturated.

According to the third aspect of the present invention, the charge stored in the voltage storage capacitor can be prevented from being consumed, so that when the voltage is not supplied to the booster circuit due to the damage of the vehicle-mounted power supply or the like, The ignition device can be quickly energized by the voltage held in the voltage storage capacitor, and the occupant protection system can be operated reliably.

According to a fourth aspect of the present invention, an occupant protection system mounted on a truck is surely operated by a single power supply device for a truck mounted with a vehicle-mounted power supply having different voltage standards of 12V and 24V. It has the effect of being able to do so.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a power supply device according to the present invention.

FIG. 2 illustrates an operation of a transistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply device 2 Current supply circuit 3 Diode 4 Diode 5 Power supply input terminal 6 Diode 8 Capacitor 9 Zener diode 10 Darlington transistor 11 Boost circuit 12 Logic circuit power supply 13 Collision judgment circuit 14 Capacitor 15 Transistor 16 Squib 21 First terminal 22 Second Terminal 23 Third terminal

Claims (4)

[Claims] An occupant protection system power supply (1) that operates on an onboard power supply and energizes an ignition device (16) provided in the occupant protection system, wherein an input supplied with a DC voltage from the onboard power supply. Terminal (1
7) and a booster circuit (11) including an output terminal (18) for outputting a DC voltage having a predetermined voltage value to the ignition device (16); and an output terminal (18) of the booster circuit (11). Voltage storage capacitor provided to store electric charge (14)
A first terminal (21) connected to the on-board power supply, a second terminal (22) connected to the input terminal (17) of the booster circuit (11), and a resistor ( r2) a Darlington transistor (10) having a third terminal (23) connected thereto; a collision judging circuit (13) for judging whether or not the ignition device (16) should be energized; The second terminal (2) of (10)
2) a logic circuit power supply (12) connected in parallel with an input terminal (17) of the booster circuit (11) and operating the collision determination circuit (13); A current supply circuit (2) for connecting an output terminal (18) of the above and the third terminal (23) of the Darlington transistor (10) via a resistor (R). Power supply (1). 2. The Darlington transistor (10).
The third terminal (23) is connected between the third terminal (23) and the first terminal (21), and the third terminal (23) is configured to preferentially guide a current flowing through the current supply circuit (2) to the third terminal (23). Terminal (2
The power supply (1) for an occupant protection system according to claim 1, further comprising a first diode (3) reversely connected to (3). 3. The voltage storage capacitor (14),
The booster circuit (1) to which the current supply circuit (2) is connected
3. The method according to claim 1, further comprising a second diode provided between the output terminal and the second diode, the second diode being reversely connected to the voltage storage capacitor.
The power supply device for an occupant protection system according to the item (1). 4. A power supply device for the occupant protection system (1).
The power supply (1) for an occupant protection system according to any one of claims 1 to 3, wherein the power supply is a power supply for operating an occupant protection system mounted on a truck.