JPH0558518U - Vehicle occupant protection device - Google Patents

Abstract

(57) [Abstract] [Purpose] By checking whether or not the capacitor has the correct capacity, the circuit scale is reduced by configuring only one capacitor. [Configuration] Reference time T1 for judging the quality of the backup capacitor 7 The timer 24 is set to, and the timer 24, which starts its operation by switching the ignition switch 2 to the ON state, is compared with the reference voltage and the charging voltage accompanying the charging of the backup capacitor 7, and the charging voltage exceeds the reference voltage. When the set signal is supplied from the comparison circuit 25 before the reset signal is supplied from the timer 24, the latch circuit 26 that latches the set signal is provided. Is supplied to the diagnostic circuit 10.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an occupant protection device for a vehicle, which is provided in an automobile or the like and deploys an airbag to protect the driver's body when the vehicle body collides.

[0002]

[Prior Art]

 As a conventional vehicle occupant protection device, for example, there is one as shown in FIG. In FIG. 3, reference numeral 1 is an on-vehicle battery, 2 is an ignition switch, 3 is a controller to which the power supply voltage of the on-vehicle battery 1 is supplied via the ignition switch 2, 4 is a DC power supply unit for airbag deployment, and a DC / DC converter 5 , A resistor 6, two capacitors 7a and 7b connected in parallel, a diode 9 for preventing inrush current to the capacitors 7a and 7b, and diodes 8a, 8b and 8c for preventing backflow. Reference numeral 10 denotes a processing circuit, which includes a CPU 10a and the like. A processing circuit power supply unit 11 switches a predetermined voltage based on the power supply voltage of the on-vehicle battery 1 in accordance with the ON / OFF state of the ignition switch 2 and supplies the processing circuit 10 and the nonvolatile storage unit 12. Reference numeral 12 is a storage unit for exchanging data with the processing circuit 10, 13a to 13e are backflow preventing diodes, and 14 to 19 are collision detection units provided at predetermined portions of the vehicle body, which are closed due to changes in the vehicle body acceleration speed. The acceleration switches 14a to 19a are formed, and the resistors 14b to 19b connected in parallel to the acceleration switches 14a to 19a, respectively. Reference numeral 20 denotes a squib provided in the steering section, which is an electrode for igniting explosive for deploying an airbag (not shown) provided in the steering section. Reference numeral 21 is a flexible spiral cable wound around the steering shaft for electrically connecting the squib 20 and the controller 3 on the vehicle body side. The collision detection units 14 and 15 are connected in parallel with each other, and the collision detection units 16 to 19 are connected in parallel with each other. These two parallel circuits are connected in series with the spiral cable 21 and the squib 20. It is connected to the.

Next, the operation of the above configuration will be described. When the ignition switch 2 is closed, the power supply voltage from the in-vehicle battery 1 is supplied to the direct-current power supply unit 4 for air bag expansion, where it is boosted by the DC / DC converter 5. The boosted voltage charges the capacitors 7a and 7b with a time constant determined by the resistor 6 and the capacitors 7a and 7b. The capacitors 7a and 7b form a backup capacitor 7. As a result, the terminal voltages of the capacitors 7a and 7b are always higher than the power supply voltage of the vehicle-mounted battery 1. At this time, all of the acceleration switches 14a to 19a are released, so that all the resistors 14b to 19b are connected as the load of the air bag expansion DC power supply unit 4. Therefore, the load current is small. Further, data such as the terminal voltage of the capacitor 7 and the terminal voltages of the resistors 14b to 19b are input to the processing circuit 10, and these terminal voltages are monitored.

In this state, when a vehicle collides and a negative acceleration more than a predetermined value is generated due to the collision, either or both of the acceleration switches 14a to 15a and any of the acceleration switches 16a to 19a are closed. Or, the state is close to a short circuit. For example, if the acceleration switches 14a and 16a are closed, the acceleration switches 14a and 16a are stored in the non-volatile memory unit 12, and the terminal voltages of the resistors 14a and 19b fall below the normal values. Memorized in. Along with this, the electric charges charged in the capacitors 7a and 7b are rapidly discharged, and the discharge current is as shown by the dotted line in the figure, the acceleration switch 14a, the diode 13a, the spiral cable 21, the squib 20, and the spiral cable 21. , Diode 13b, and acceleration switch 16a to ground. This discharge current causes the squib 20 to generate heat, which ignites the explosive powder, and the explosive force thereof causes the airbag to expand.

[0005]

[Problems to be solved by the device]

 However, in such a conventional vehicle occupant protection system, the use of two large capacitors 7a and 7b as a power source for deploying the airbag causes a capacity shortage due to deterioration of the capacitor. In that case, there is a problem that the circuit unit becomes large because the compensation is performed, and the cost of the large-capacity capacitor increases because the price is high. In addition, when a fatal failure such as a short-circuit failure occurs in one of the capacitors, there is a problem that the meaning of the redundant design is lost.

The present invention was made in view of such conventional problems, and an object thereof is to solve the above problems by checking whether or not a capacitor has a correct capacity. There is.

[0007]

[Means for Solving the Problems]

 The vehicle occupant protection system according to the present invention is provided with a function for checking an abnormality such as the capacity of the capacitor.

[0008]

[Action]

 According to the vehicle occupant protection device of the present invention, it is checked whether or not the capacity of the capacitor is normal, so that it is not necessary to provide a plurality of capacitors having a particularly large capacity.

[0009]

【Example】

The invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the present invention, in which only the capacitance check circuit of the capacitor 7 is shown. 1 and 2, the input voltage V0 Drives the timer 24, and the resistor R 1 Through which the capacitor 7 is charged. This charging voltage VC Is applied to the comparator (comparison circuit) 25 and the reference voltage VS Compared with VC ≧ VS At this time, the flip-flop (latch circuit) 26 is set. The timer 24 has a voltage v0 T1 after being driven by Until the time elapses, the flip-flop 26 is reset.

Next, the operation will be described. Capacitance C1 of capacitor 7 Is within the normal range, the charging voltage VC Is gradually increased, the above predetermined time T1 After passing over the reference voltage VS Reach As a result, the flip-flop 26 is set, its Q output becomes "H" level, and it is found that the capacitor 7 is normal. Capacitance C1 of capacitor 7 Is small, the charging voltage VC Rises quickly, and the predetermined time T1 Within the reference voltage VS However, since the flip-flop 26 is in the reset state at this time, the Q output remains at "L" level. According to the above, the voltage V0 For a predetermined time T1 The abnormality of the capacitor 7 can be checked by monitoring the state of the Q output after the passage of.

[0011]

[Effect of the device]

 As described above, according to the present invention, since the configuration is configured to check for an abnormality in the capacitor that serves as the power source for deploying the airbag, it is not necessary to use two large-capacity capacitors as in the conventional case. By using a capacitor with a predetermined capacity, the circuit scale can be reduced and the cost can be reduced. In addition, the effect that can be easily detected can be obtained only with the hardware configuration.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a capacitor capacity check circuit portion of a vehicle occupant protection system according to an embodiment of the present invention.

FIG. 2 is an output waveform diagram of each unit in FIG.

FIG. 3 is a block diagram of a conventional airbag system.

[Explanation of symbols]

 1 Car Battery 2 Ignition Switch 3 Operation Control Circuit 7 Backup Capacitor 10 Processing Circuit (Diagnostic Circuit) 14-19 Collision Detection Circuit 24 Timer 25 Comparison Circuit 26 Flip-Flop (Latch Circuit)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hirohisa Nakata 2-1910 Nisshin-cho, Omiya-shi, Saitama, Kansei Stock Company (72) Mikio Kawaguchi 2-1910 Nisshin-cho, Omiya-shi, Saitama Kansei Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. An operation control circuit, which is provided between terminals of an on-vehicle battery via an ignition switch and deploys an airbag based on a detection output from a collision detector,
A vehicle occupant protection device comprising: a backup capacitor for expanding the airbag, which is inserted between the ignition switch and an operation control circuit; and a diagnostic circuit having a function of checking an abnormality of the backup capacitor, A timer time is set to the reference time for determining the quality of the backup capacitor, and the timer that starts operation by switching the ignition switch to the on state is compared with the charging voltage and the reference voltage accompanying the charging of the backup capacitor, and charging is performed. A comparator circuit that outputs a set signal when the voltage exceeds the reference voltage, and a latch circuit that latches the set signal when the set signal is supplied from the comparator circuit before the reset signal is supplied from the timer. And providing the output of the latch circuit to the diagnostic circuit. Vehicle occupant protection apparatus according to claim.