JP3634016B2 - Vehicle occupant protection device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an occupant protection device for a vehicle that is used to instantly inflate an airbag at the time of a vehicle collision accident to protect the occupant from the accident.
[0002]
[Prior art]
A conventional vehicle occupant protection device of this type will be described with reference to FIG.
1 is an in-vehicle battery, 2 is a DC / DC converter, and a collector is connected to a connection point between the coil 2a connected in series, the first backflow prevention diode 2b, and the coil 2a and the first backflow prevention diode 2b. The emitter is grounded, and the base has a transistor 2c that is on / off controlled by a periodic pulse supplied from an output terminal P1 of a microcomputer (control circuit) 19 described later. The terminal of the DC / DC converter 2 on the side not connected to the first backflow prevention diode 2b of the coil 2a is connected to the onboard battery 1 via the second backflow prevention diode 3 and is mounted on the vehicle. The output current of the battery 1 is applied to the coil 2a based on the periodic pulse to boost and output. Reference numeral 6 denotes a third backflow prevention diode, whose anode is connected to the in-vehicle battery 1 and whose cathode is connected to the cathode of the fourth backflow prevention diode 10 and the output terminal of the DC / DC converter 2. 7 has the same function as the third backflow prevention diode 6 and is connected to the cathode of the fourth backflow prevention diode 11 and the output terminal of the DC / DC converter 2.
[0003]
Denoted at 4 and 5 are detonator drive control circuits (including the third backflow prevention diodes 6 and 7), each having the same function and being composed of the same or equivalent ones. That is, the third and fourth backflow prevention diodes indicated by reference numerals 6 and 10 are the third and fourth backflow prevention diodes indicated by reference numerals 7 and 11, the backup capacitor indicated by reference numeral 8 is the backup capacitor indicated by reference numeral 9, The inrush current preventing resistor indicated by reference numeral 13 corresponds to the inrush current preventing resistor indicated by reference numeral 13, and the switching transistor (switch circuit) indicated by reference numeral 14 corresponds to the switching transistor indicated by reference numeral 15, each detonator drive control circuit. 4 and 5 are connected in series between the mechanical acceleration sensor 18 and the power source circuit formed by the DC / DC converter 2 and the battery 1, with the detonator 16 or 17 being connected in series on each output side. Has been. Reference numeral 19 denotes a control circuit. When power is turned on, a periodic pulse is supplied from the output terminal P1 to the transistor 2c, and the transistor 2c is periodically turned on and off. On the other hand, if an acceleration signal is input from the input terminal A and the magnitude of the collision is determined to determine a serious collision, the output terminal P2 is set to the low level for a certain time, and the switch circuits 14 and 15 are simultaneously turned on.
[0004]
The connection relationship of the above components will be described below. Since the detonator drive control circuits 4 and 5 are the same, only the detonator drive control circuit indicated by reference numeral 4 will be described.
That is, the output terminal of the DC / DC converter 2, that is, the cathode of the first backflow prevention diode 2b is grounded via the inrush current prevention resistor 12 and the backup capacitor 8 in series. A fourth backflow prevention diode 10 is connected in parallel to the inrush current prevention resistor 12, and the cathode of the fourth backflow prevention diode 10 is connected in common to the cathode of the third backflow prevention diode 6. The connection point is connected to one end of the first detonator 16 via a switch circuit 14 composed of a switching transistor, and the other end of the first detonator 16 is connected to the second detonator 17 via a common mechanical acceleration switch 18. Grounded.
[0005]
That is, in the above configuration, power supply is started by the in-vehicle battery 1, and at the same time, the backup capacitor 8 starts to be charged toward the battery voltage via the third backflow prevention diode 6 and the inrush current prevention resistor 12 in series. On the other hand, the transistor 2c is turned on and off by a periodic pulse from the output terminal P1 of the control circuit 19, and a high voltage is generated between the terminals of the coil 2a, whereby the charging voltage of the backup capacitor 8 is boosted to the battery voltage or higher. The
At the same time, it goes without saying that the backup capacitor 9 is also charged by the DC / DC converter 2 or the like in the same manner as described above.
[0006]
Next, an acceleration signal due to the collision is supplied from the terminal A to the control circuit 19, and when the control circuit 19 determines that the collision is serious, the control circuit 19 sends a pulse signal from the output terminal P2, in this case, a low level signal to the switch circuit. When the switch circuits 14 and 15 are turned on by supplying them to both 14 and 15, the charges charged in both the backup capacitors 8 and 9 are transferred to the detonators 16 and 17 through the fourth backflow prevention diodes 10 and 11. An air bag or the like is activated in both directions to protect the occupant from accidents. Of course, at this time, it goes without saying that the mechanical acceleration switch 18 is on.
[0007]
[Problems to be solved by the invention]
However, in the vehicle occupant protection device described above, the inrush current prevention resistor connected in series to each backup capacitor is a discrete element having a large capacity, whereas the other mounted components are surface mounted components. As a result, the density could not be increased, which was a factor in increasing costs. In addition, there is a problem that the installation space must be large.
[0008]
Accordingly, the present invention has been made paying attention to the above-mentioned problems, and the above problem can be solved by using a single inrush current preventing resistor for the backup capacitor and a surface mountable backflow preventing diode. The purpose is to solve the problem.
[0009]
[Means for Solving the Problems]
The vehicle occupant protection device according to the present invention is connected in parallel to a DC / DC converter 2 in which a resistor 2d , a coil 2a , a first backflow prevention diode 2b are connected in series, and an output terminal of the DC / DC converter 2. cathode Te, a plurality of backup capacitor 8 and 9 is charged, the second reverse blocking diode 3 having an anode on the input side is connected to the DC / DC converter 2, with the cathode of the second reverse-flow preventing diode 3 the third reverse-flow preventing diode 6 connected to the vehicle battery, the fourth reverse-flow preventing diode 10, 11 having a cathode connected to the output side of the DC / DC converter 2, the diode 6, 10 and to each common connection point of the anode over de side of 7,11, Sukuibu 16 connected in series via the respective switch circuits 14, 15, 7, in order to generate the boosted voltage between the terminals of the coil 2a of the DC / DC converter 2 outputs a periodic pulse to act intermittently current to the coil 2a, based on the acceleration signal generated by the impact determine the magnitude of the collision, on of the switch circuits 14 and 15, formed by e Bei a control circuit 19 for outputting a signal for controlling the off.
[0010]
[Action]
According to the above invention, when a power switch (not shown) is turned on, the current from the in-vehicle battery 1 is always limited via the inrush current preventing resistor 2d in the DC / DC converter 2 , and the backup capacitors 8, 9 Is charged to the battery voltage.
When the control circuit 19 starts operating, the backup capacitor 2 is charged to a voltage higher than the battery voltage by the voltage generated by the boosting action of the DC / DC converter 2. At this time, the charging current is limited by the inrush current preventing resistor 2d . The backup capacitor 2 is charged.
[0011]
【Example】
The configuration of an embodiment according to the present invention is shown in FIG. 1. In this figure, the same or equivalent parts as those described in the conventional example of FIG. Only different parts will be described below.
[0012]
First, an inrush current preventing resistor 2d having a value 2 to 3 times the DC resistance value of the coil 2a is inserted between the second backflow preventing diode 3 and the coil 2a, and the inrush current in FIG. The point that the resistances 12 and 13 for prevention are lost. The inrush current prevention resistor 2d is inserted on the connection line between the coil 2a and the first backflow prevention diode 2b and between the connection point of the collector of the transistor 2c and the output terminal of the coil 2a. It goes without saying that it is good.
[0013]
Second, there is a line connecting the connection point between the third and fourth backflow prevention diodes 6 and 10 and the connection point between the first backflow prevention diode 2b and the inrush current prevention resistor 12 in FIG. This is because the current charged from the on-vehicle battery 1 to the backup capacitor 8 is supplied only through the DC / DC converter 2 without going through the third backflow prevention diode 6.
[0014]
Third, there is a line connecting the connection point between the third and fourth backflow prevention diodes 7 and 11 and the connection point between the first backflow prevention diode 2b and the inrush current prevention resistor 13 in FIG. In other words, the current charged from the in-vehicle battery 1 to the backup capacitor 8 is supplied only through the DC / DC converter 2 without passing through the third backflow prevention diode 7.
[0015]
【The invention's effect】
As described above, according to the present invention, the backup capacitor is always charged by the current from the in-vehicle battery limited via the inrush current prevention resistor in the DC / DC converter, so that the inrush current prevention resistance is DC Only one provided in the DC converter is sufficient, and the number of parts can be reduced. Further, reverse current blocking diode may if it is possible to prevent a reverse current from the backup capacitor, it is not necessary to flow a charging current to the backup capacitor through the diode for preventing reverse current, you can use a surface mountable diode. As a result, the mounting area can be reduced, and many mounting components can be soldered by surface mounting, so that the effect of reducing costs can be achieved.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of a vehicle occupant protection device according to an embodiment of the present invention.
FIG. 2 is a circuit block diagram of a conventional vehicle occupant protection device.
[Explanation of symbols]
2a Coil 2c Transistor 2b, 3, 6, 7, 10, 11 Backflow prevention diode 4, 5 Detonator drive control circuit 8, 9 Backup capacitor 14, 15 Switch circuit 16, 17 Detonator 19 Control circuit

Claims (1)

A DC / DC converter 2 in which a resistor 2d , a coil 2a , and a first backflow prevention diode 2b are connected in series; a plurality of backup capacitors 8 connected in parallel to the output terminal of the DC / DC converter 2 and charged ; 9, the second reverse blocking diode 3 whose anode is connected to the input side of the DC / DC converter 2, the third backflow prevention of connecting the cathode to the vehicle battery with the cathode of the second reverse-flow preventing diode 3 a diode 6 and 7, a fourth reverse current blocking diode 10, 11 having a cathode connected to the output side of the DC / DC converter 2, the common connection point of the anodic side of the diode 6, 10 and 7, 11 respectively, and Sukuibu 16, 17 which are connected in series via the respective switch circuits 14 and 15, of the DC / DC converter 2 In order to generate the boosted voltage between yl 2a of terminals, and outputs a periodic pulse to act intermittently current to the coil 2a, determines the magnitude of the collision based on the acceleration signal generated by the impact, said switch on the circuits 14 and 15, the vehicle occupant protection apparatus in which example Bei and a control circuit 19 for outputting a signal for controlling the off.

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