JPH07159470A - Crew potective device for vehicle - Google Patents

Abstract

PURPOSE:To reduce the number of voltage checking points for diagnosing the capacitances of backup capacitors and the number of input ports of a microcomputer to which checked voltages are inputted. CONSTITUTION:Rush current preventing resistors 7 and 13 are commonly connected to the output terminal of a DC-DC converter 2 and the output voltage of the converter 2 can be obtained as a reference voltage. The capacitances of backup capacitors 6 and 12 are diagnosed by inputting the reference voltage and the input- or output-side voltages of discharge diodes 8 and 14 to a microcomputer 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag for protecting an occupant of a vehicle from a collision accident, and more particularly to a vehicle occupant protection device having a plurality of ignition detonators.

[0002]

2. Description of the Related Art A conventional vehicle occupant protection system will be described with reference to FIG. In FIG. 2, reference numeral 1 is a vehicle-mounted battery, and 2 is a DC / DC that boosts and outputs the output voltage of the battery 1.
The input terminal of the converter is connected to the battery 1 via the first backflow prevention diode 3. 4 is a second backflow prevention diode, the anode of which is the battery 1
And the cathode is connected to the cathode of a third backflow preventing diode 5 described later. The first
Also, an ignition switch (not shown) is inserted in a connection line between the anodes of the second backflow preventing diodes 3 and 4 and the battery 1. The anode of the third backflow preventing diode 5 is the DC / DC converter 2
Is connected to the output terminal of.

Reference numeral 6 is a first backup capacitor, which is connected to the cathodes of the second and third backflow preventing diodes 4 and 5 through an inrush current preventing resistor 7. 8, 9
Are parallel-connected first and second discharging diodes, the anodes of which are connected to the non-grounded side terminal of the first backup capacitor 6 and the cathodes of which are the inrush current preventing resistor 7 and the third reverse current preventing resistor. It is connected to the connection point with the diode 5.

Reference numeral 10 denotes a fourth backflow prevention diode, the anode of which is connected to the battery 1 and the cathode of which is connected to the cathode of a fifth backflow prevention diode 11 which will be described later. The anode of the fifth backflow prevention diode 11 is
It is connected to the output terminal of the DC / DC converter 2. Reference numeral 12 is a second backup capacitor, which is connected to the cathodes of the fourth and fifth backflow preventing diodes 10 and 11 via a rush current preventing resistor 13.

Reference numerals 14 and 15 denote third and fourth discharging diodes connected in parallel, the anodes of which are connected to the non-ground side terminals of the second backup capacitor 12 and the cathodes thereof being the inrush current preventing resistor 13. And the fifth backflow preventing diode 11 are connected to each other.

The first circuit including the second and third backflow preventing diodes 4, 5, the first backup capacitor 6, the first inrush current preventing resistor 7, the first and second discharging diodes 8, 9 is Fourth and fifth backflow prevention diode 1
0, 11, a second backup capacitor 12, a second inrush current preventing resistor 13, a third and a fourth discharging diode 1
It has the same function as the second circuit of 4 and 15 and is connected in parallel. A power supply circuit 16 is constituted by the first and second circuits, the battery 1, the first backflow prevention diode 3, and the DC / DC converter 2.

Reference numeral 17 is a first switch circuit, the input terminal of which is the output terminal of the first circuit, that is, the cathodes of the second and third backflow preventing diodes 4, 5 and the first and second discharging diodes 8, 9. Is connected to the first detonator 21 to limit the current supply amount.

Reference numeral 18 is a second switch circuit having the same function as that of the first switch circuit 17, the input terminal of which is the output terminal of the second circuit, that is, the fourth and fifth backflow preventing diodes 10, 11 and the third. , Fourth discharging diode 1
The second detonator 22 which will be described later is connected to the cathodes 4 and 15.
The amount of current supplied to the circuit is limited by a signal from the microcomputer 19 described later.

Reference numeral 19 denotes a microcomputer, which determines the magnitude of a collision accident based on an acceleration signal (generated at the time of collision) supplied to the terminal A, and the first and second switch circuits are supplied through an energization control circuit 20. A trigger signal for turning on each of 17 and 18 for a predetermined time is output. In addition, the microcomputer 19 operates for a predetermined time immediately after the ignition switch is turned on, for example, as shown in FIG.
In the period from time t1 to time t2, the first and second switching transistors 26 and 28, which will be described later, are maintained in the off state, and the first backup capacitor 6 is
Then, the capacity C1 is calculated. C1 = -t0 / (R1 · ln (1-V1 / V0)) where R1 is the resistance value of the inrush current preventing resistors 7 and 13.

After that, until time t3 following time t2, the microcomputer 19 supplies a diagnostic pulse signal to the first and second switching transistors 26 and 28, which will be described later, until the voltage at the point B reaches V2. At the time when it decreases, the capacitance C1 of the first backup capacitor 6 is calculated by the following equation. C1 = -t1 / (Ra.ln ((V2-Va) / (V0-Va))) Va = R2.V0 / (R1 + R2) Ra = R1.R2 / (R1 + R2) That is, the microcomputer 19 is the above. In the charging and discharging shown in FIG.
The capacities of the backup capacitors 6 and 12 are calculated, and if one of these capacities does not fall within a predetermined range, it is judged that the capacity is abnormal and an abnormality notification signal is output from the F terminal to a notifying means (not shown). To do. It goes without saying that the microcomputer 19 needs an A / D converter when inputting the voltage from each check point.

Reference numerals 21 and 22 denote first and second detonators, one ends of which are connected to the output terminals of the corresponding first and second switch circuits 17 and 18, respectively. The other ends of the first and second detonators 21, 22 are connected to one end of a mechanical acceleration switch 25 via the corresponding first and second diodes 23, 24. The acceleration switch 25 is controlled to be turned on and off between its input and output by a magnetic force of a magnet that is displaced by receiving acceleration, and its other end is grounded.

Reference numeral 26 is a first switching transistor which is normally in an off state, the collector of which is connected to the non-grounded side of the first backup capacitor 6 via a resistor 27, the emitter of which is grounded, and the base of which is a microcomputer 19. When a predetermined pulse is supplied from the microcomputer 19 connected to the output terminal of the above, it is turned on, and the electric charge charged up to that point is discharged through the resistor 27. A second switching transistor 28 has the same function as the first switching transistor 26 with respect to the second backup capacitor 12.

In the above structure, when the microcomputer 19 determines that a serious accident has occurred based on the acceleration signal supplied to the terminal A, and the acceleration switch 25 is closed, the microcomputer 19 determines that the predetermined accident has occurred. By turning on the energization control circuit 20 for a period of time,
The first and second switch circuits 17 and 18 are turned on.

At this time, when the power supply circuit 16 is operating normally, the output current from the DC / DC converter 2 is the third reverse current prevention diode 5 and the first switch circuit 1.
7, first detonator 21, diode 23, acceleration switch 2
5 and the fifth backflow prevention diode 1
1, the second switch circuit 18, the second detonator 22, the diode 24, and the acceleration switch 25 also flow in this order.

When the battery 1 is destroyed due to a collision, for example, instead of supplying the output current from the DC / DC converter 2, the electric charges charged in the first and second backup capacitors 6 and 12 are charged. Flows in the order of the third backflow prevention diode 5, the first switch circuit 17, the first detonator 21, the diode 23, and the acceleration switch 25, and the fifth backflow prevention diode 11, the second switch circuit 18, and the second detonator 22. , The diode 24, and the acceleration switch 25 also flow in this order to activate the respective airbags.

Furthermore, when the power is turned on, DC / D
The output voltage of the C converter 2 rises rapidly as shown by the symbol A in FIG. 3, and at the same time the second backup capacitor 12 is charged (in the sections T1 and T3 of the voltage waveform of the curve B in FIG. 3). (Shown), constant voltage V
Saturate to 0.

On the other hand, in the microcomputer 19, when the time T1 elapses and the voltage value of the first backup capacitor 6 reaches V1, the time T1 required to reach the voltage V1 falls within the set reference time. Diagnose whether it is included. At time t2 when the voltage V1 is reached, the microcomputer 19 supplies a pulse to the first switching transistor 26 only during the time T2.

As a result, the first backup capacitor 6
Is the time t3 required for the terminal voltage to drop below the voltage V2 to be an appropriate time (including an error range) when the electric charge charged to the terminal is discharged through the resistor 27 and the first switching transistor 26, or The microcomputer 19 determines whether there is an abnormality, and when it determines that there is an abnormality, it outputs an abnormality notification signal F.

Thereafter, after the electric charge charged in the second backup capacitor 12 is discharged to the other second backup capacitor 12 by turning on the second switching transistor 28, the same operation as described above is performed. Perform fault diagnosis.

[0020]

However, in such an occupant protection device for a vehicle, the first and second backup capacitors 6 and 12 are connected in series to diagnose each other. The voltage generated between both terminals of the inrush current prevention resistors 7 and 13 is read into the microcomputer 19, and the capacitance values of the first and second backup capacitors are appropriately maintained without deterioration based on the voltage. Since the configuration is such that whether or not there is a diagnosis is made, the number of voltage check points read into the microcomputer 19 is required to be twice the number of backup capacitors. Therefore, as the number of backup capacitors increases, the input of the microcomputer increases. There was a problem that many ports were required.

Further, since the voltage value is an analog signal, an A / D converter is required on the input line to the microcomputer 19, which causes a problem of cost increase.

That is, the voltage lines C and E in FIG.
Are supplied via different backflow prevention diodes 5 and 11, respectively. Therefore, there is a problem in that only one of them cannot be treated as a reference because the voltage values are not the same due to the difference in characteristics.

The present invention has been made in view of such a problem, and reduces the number of voltage check points for diagnosing the capacity of a backup capacitor, and inputs the check voltage. The purpose is to reduce the number.

[0024]

A vehicle occupant protection system according to the present invention comprises a DC / DC converter for boosting and outputting a voltage from a battery, and a DC / DC converter connected in parallel to an output terminal of the DC / DC converter. First and second series circuits composed of a plurality of inrush current preventing resistors and first and second backup capacitors; first and second diodes each having an anode connected in parallel to an output terminal of the battery; and the first An anode is connected to a connection point between the resistor for preventing inrush current of the series circuit and the first backup capacitor, and a cathode is connected to a cathode of the first diode so that the cathode forms a first output terminal. , An anode is connected to a connection point between the inrush current preventing resistor of the second series circuit and the second backup capacitor, and the cathode is the second diode. A fourth diode having the cathode to form a second output terminal connected to the cathode of a de, third
And the first and second detonators connected via a switch circuit to the respective output terminals formed by the respective cathodes of the fourth diode and the fourth diode, and the acceleration signal associated with the collision is input to determine the magnitude of the collision. , Supplying a trigger signal to each of the switch circuits as needed, and based on each of the potential differences on the cathode side or the anode side of the third and fourth diodes based on the output voltage of the DC / DC converter. A microcomputer that detects the magnitude of the capacitance of the first and second backup capacitors to perform a failure diagnosis of the first and second backup capacitors, and outputs a failure notification signal when it is determined that there is a failure and its equivalent. And are equipped with.

[0025]

According to the vehicle occupant protection device of the present invention, since each of the inrush current preventing resistors is commonly connected to the output terminal of the DC / DC converter, the DC / D
Since the output voltage of the C converter can be obtained as the reference voltage, the capacity diagnosis of the backup capacitor can be performed by inputting the reference value and the voltage on the input side or the output side of each discharging diode to the microcomputer. .

By this, the discharging diode 8,
In the event of failure of 14 in the non-conducting (disconnection) state,
The voltage value on the cathode side of the discharging diode 8 is the battery 1
Since it drops to the voltage, the microcomputer 2
Monitoring by 6 enables fault diagnosis of the discharging diodes 8 and 14. Further, when a failure in the conductive (short) state occurs, the charging voltage rises quickly, and the microcomputer 26 monitors the rising of the charging voltage, so that the failure diagnosis of the discharging diodes 8 and 14 can be performed.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG.
Although the configuration will be described based on FIG. 1, the same configuration as that described in FIG. 2 or equivalent components will be denoted by the same reference numerals and the description thereof will be omitted, and only different configurations will be described.

That is, in FIG. 1, the third and fifth backflow preventing diodes 5 and 11 in FIG. 2 are omitted,
Accordingly, the voltage Z on the output line of the DC / DC converter 2, the voltage X on the output line on the cathode side of the first discharging diode 8, and the voltage Y on the output line on the cathode side of the second discharging diode 12 fail. It is supplied to the microcomputer 30 for diagnosis.

That is, this microcomputer 30
Inputs the output voltage of the DC / DC converter 2 as the value of V0 in the two equations shown in the above-mentioned conventional example, and also supplies the cathodes of the discharging diodes 8 and 14 and the discharging diodes 8 and 14 respectively. The voltages at points X and Y on the connection line with the input terminals of the first and second switch circuits 17 and 18 to be connected are input to both the first and second backup capacitors 6 and 1, respectively.
Calculate the capacity of 2. As a result, when the capacitance value does not fall within the predetermined range, the failure notification signal is output from the F terminal.

After the diagnosis is completed, the microcomputer 30 monitors whether or not the output voltage of the DC / DC converter 2 matches, and when the output voltage of the battery 1 is reduced, the microcomputer 30 is for discharging. It is determined that the diodes 8 and 14 are in a non-conducting state and have failed, and the failure notification signal indicating that fact is output from the F terminal.

Immediately after the ignition switch is turned on and the charging of the first and second backup capacitors 6 and 12 is started, the rising state of the voltage at each of the points X and Y becomes earlier than a predetermined value. In this case, it is determined that the discharging diodes 8 and 14 have become conductive and have failed, and a failure notification signal indicating that fact is output from the Z terminal. This is because when the discharging diodes 8 and 14 become conductive, the backup capacitors 6 and 12 do not go through the inrush current preventing resistors 7 and 13 but the second and fourth backflow preventing diodes 4 and 10. This is because the portion directly charged from the battery 1 increases. In the above embodiment, the voltages at the X and Y points on the cathode side of the discharging diodes 8 and 14 are supplied to the microcomputer 30, but the voltages on the anode side may be supplied.

[0032]

As described above, according to the present invention, the number of voltage check points for the capacity diagnosis of the backup capacitor can be reduced, so that the number of input ports for the diagnosis of the microcomputer can be reduced. The effect is demonstrated.

[Brief description of drawings]

FIG. 1 is a circuit explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional circuit.

FIG. 3 is a waveform diagram for explaining the operation of FIG.

[Explanation of symbols]

 2 DC / DC converter 3, 4, 10 Reverse current prevention diode 6, 12 Backup capacitor 7, 13 Inrush current prevention resistor 8, 14 Discharge diode 17, 18 Switch circuit 20 Current control circuit 21, 22 Detonator 25 Acceleration switch 26 , 28 switching transistors 30 Microcomputer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Shibata, 1910 Nisshincho, Omiya City, Saitama Prefecture Kansei Co., Ltd.

Claims (1)

[Claims] 1. A DC / DC converter (2) for boosting and outputting a voltage from a battery (1), and a plurality of inrush current preventing resistors (7) connected in parallel to an output terminal of the DC / DC converter. ), (13) and first and second backup capacitors (6), (12), and a first and a second series circuit having an anode connected in parallel to the output terminal of the battery (1). Second diode (4),
An anode is connected to a connection point between the inrush current prevention resistor (7) and the first backup capacitor (6) of the first series circuit (10), and the cathode is the cathode of the first diode (4). An anode is provided at a connection point between a third diode (8) connected to the cathode to form a first output terminal, a rush current preventing resistor (13) of the second series circuit, and a second backup capacitor (12). A fourth connected to the cathode of the second diode (10), the cathode forming a second output terminal
A switch circuit (17), (1) is provided to each of the output terminals formed by the diode (14) and the cathodes of the third and fourth diodes (8), (14).
8) a first and a second detonator (21) connected via
(22) and the acceleration signal associated with the collision are input to determine the size of the collision, and the switch circuit (1
7) and (18) are each supplied with a trigger signal, and the cathode side or the anode side of the third and fourth diodes (8) and 14) based on the output voltage of the DC / DC converter (2). The first and second backup capacitors (6) based on the respective potential differences of
A microcomputer (30) for detecting the magnitude of the capacity of (12) to perform a failure diagnosis of the first and second backup capacitors and outputting a failure notification signal when it is determined that there is a failure and its equivalent. A vehicle occupant protection device characterized by the following.