JP2000219100A - Occupant protection device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify constitution of a receiving circuit to reduce cost by constituting the receiving circuits on the host/slave microcomputer sides to be respectively a current detecting type and a voltage detecting type. SOLUTION: Current detecting type circuits 50, 51 of a air bag unit 1 for front collision are constituted of current detecting resistances 19, 18, pull-up resistance 48, reference voltage generating resistances 42, 46, and computation amplifiers 41, 45, and the current detecting resistances 19, 18 are interposed in series on power supply lines B, A to side air bag units 3, 2 for a front passenger seat and a driver's seat. The reference voltage generating resistances 42, 46 are interposed between a gland and the connecting line between a step-up circuit 6 and the current detecting resistances 19, 18, the output voltage of the step-up circuit 6 is divided by resistance to supply to the computation amplifiers 41, 45, by the computation amplifiers 41, 45 of which the output ends are connected to a power supply line through the pull-up resistance 48, the reference voltage is compared with voltage on the negative side of the current detecting resistances 19, 18, and supplied to a fourth communication circuit 13C. In this way, constitution of a receiving circuit can be simplified to reduce cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle occupant protection device including a plurality of airbags or the like which are deployed, for example, in the event of a vehicle collision to protect occupants.

[0002]

2. Description of the Related Art A conventional vehicle occupant protection device of this kind is
First, the occupant protection device shown in FIG. 3 will be described as an example. In FIG. 3, reference numeral 1 denotes a front collision airbag unit, which is supplied with power from a vehicle-mounted battery 4 via an ignition switch 5. 2 is a driver side airbag unit, 3 is a passenger side airbag unit, which are connected by multiplex communication signal lines A and B, and these multiplex signal lines A and B are also used as a power supply line. You. Next, the front airbag unit 1 and the driver's side airbag unit 2 will be described in this order, and the passenger side airbag unit 3 has the same configuration as the driver's side airbag unit 2 and will be described in detail. Is omitted.

First, the booster circuit 6 of the front airbag unit 1 boosts the output voltage supplied from the vehicle-mounted battery 4 to charge the backup capacitor 7, and
The driver side airbag unit 2 and the passenger side airbag unit 3 via signal lines A and B
Powering. The microcomputer (main microcomputer) 8 has a communication function, a collision determination function, and a diagnosis function, and inputs an acceleration signal output from the longitudinal acceleration sensor 9 when a collision occurs, according to the collision determination function, If it is determined based on the acceleration signal that a serious collision is indicated, the switch circuit 10
To the backup capacitor 7
Is supplied to the primer 11 and the mechanical acceleration switch 12, and an airbag (not shown) is deployed.
Further, the microcomputer 8 periodically generates a request signal for each of the side airbag units 2 and 3 in order to diagnose the two side airbag units 2 and 3 by the diagnostic function, and And second communication circuit (communication function) provided corresponding to
13a and 13b. As a result, the first or second switching transistor 14 or 15 is turned on and off to drive the signal lines A and B which are also power lines.
And a request signal is transmitted to the driver side airbag unit 2 and the passenger side airbag unit 3.

That is, in this communication, for example, when the first switching transistor 14 (or the second switching transistor 15) is turned on, the output voltage of the boosting circuit 6 is changed to the resistance 16 (or the resistance 17) and the resistance 18 (or the resistance 19). ), The low-level signal is transmitted, and when the signal is turned off, the output voltage of the booster circuit 6 is changed to the resistance 16 (or resistance 17) and the resistance 18 (or resistance 1).
9), a high-level signal is transmitted because resistance division is not performed.

Further, the microcomputer 8
Transmits a request signal to the driver side airbag unit 2 via a signal line A connected to the negative potential side Y of the resistor 18, and transmits a response signal from the driver side airbag unit 2 to the driver side airbag unit 2. The signal is input via a signal line N, and a failure diagnosis of the driver's seat side airbag unit 2 is performed based on the input response signal. A request signal is transmitted via a signal line B connected to the negative potential side Y 'of the resistor 19, and a response signal from the passenger side airbag unit 3 is input via a signal line M. A failure diagnosis of the passenger side airbag unit 3 is performed based on the input response signal, and when it is determined that a failure has occurred, an alarm unit (not shown) is driven to notify the failure.

Next, the driver's seat airbag unit 2
The boosted voltage is supplied via the signal line A and supplied to the constant voltage circuit 31 via the diode 30. A microcomputer (subcomputer) 32
Turns on the second switch circuit 34 and supplies the signal via the signal line A when it is determined that the collision is a serious collision based on the acceleration signal from the lateral acceleration sensor 33 generated at the time of the collision from the side of the vehicle. The boosted voltage is supplied to a primer 35 and a mechanical acceleration switch 36 to deploy an airbag (not shown) or the like. Further, the microcomputer 32 responds to the request signal supplied from the front airbag unit 1 via the signal line A in accordance with the content of the request signal (shows a diagnosis result of the primer 35 and the like).
And a third communication circuit (the first and second communication circuits 13
a), the third switching transistor 38 is turned on and off via a 37, a response signal is superimposed on a signal line A via a resistor 39, and transmitted to the front collision airbag unit 1.

In this communication, when the third switching transistor 38 is turned on, the voltage on the negative potential side Y of the resistor 18 (voltage divided by the resistor 18 and the resistor 39).
Is divided by the resistor 21 and the resistor 22 so that the signal line N
When the third switching transistor 38 is turned off, the voltage on the negative potential side Y of the resistor 18 is divided by the resistors 21 and 22 so that the high level A response signal is transmitted.

[0008]

However, the reception method of the front collision airbag unit 1, which is the main occupant protection device in the vehicle occupant protection device described above, is based on the driver side airbag unit 2, the passenger seat, and the like. When the current detection method is the same as the reception method of the auxiliary occupant protection device such as the side airbag unit 3, the circuit configuration of the front airbag unit 1 is complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the cost of the entire circuit by simplifying the configuration of a receiving circuit provided in each of the main occupant protection devices. .

[0010]

According to a first aspect of the invention, there is provided a vehicle occupant protection device comprising a main microcomputer which is supplied with power from a vehicle-mounted battery to constitute a main occupant protection device and has at least a communication input / output port; A sub-microcomputer provided in each of the sub-occupant protection devices, a power line connected between the main microcomputer and the plurality of sub-microcomputers through one communication resistor in series, and the power line A transmission circuit and a reception circuit are connected to each of the main microcomputer side and the sub microcomputer side, and the power supply line is shared as a signal line, and the main microcomputer and the sub microcomputer are respectively connected via the power supply line. In the vehicle occupant protection device performing multiplex communication, the main microphone Receiving circuit of the computer side is a current detection type and said respective receiving circuits of the sub-microcomputer side, characterized by comprising a voltage detection type.

According to a second aspect of the present invention, the receiving circuit on the main microcomputer side according to the first aspect of the invention detects a current by the communication resistor connected in series to the power supply line.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 1, components having the same configuration as in FIG. 3 or components equivalent thereto are denoted by the same reference numerals, and detailed description thereof will be omitted.
Only the different parts, that is, the current detection type receiving circuits 50 and 51 of the front airbag unit 1 and the voltage detection type receiving circuit 52 of the driver side airbag unit 2 will be described below.

One current detection type receiving circuit 50 includes a current detection resistor 19, a pull-up resistor 48, and a reference voltage generation resistor 4.
2 and an operational amplifier 41, and the current detection resistor 19 is inserted in series with a power supply line B to the passenger side airbag unit 3. The reference voltage generating resistor 42 is connected to the booster circuit 6 and the current detecting resistor 1.
9, the output voltage of the booster circuit 6 is divided by a resistor and supplied to the operational amplifier 41, and the output terminal is connected to the power supply line by a pull-up resistor 48. The amplifier 41 compares the reference voltage with the voltage on the negative side of the current detection resistor 19 and supplies the comparison result to the fourth communication circuit 13c.

The other current detection type receiving circuit 51
It comprises a current detection resistor 18, a pull-up resistor 48, a reference voltage generation resistor 46, and an operational amplifier 45. The current detection resistor 18 is inserted in series with a power line A to the driver side airbag unit 2. I have. Further, the reference voltage generating resistor 46 is interposed between a ground and a connection line between the booster circuit 6 and the current detection resistor 18 and divides the output voltage of the booster circuit 6 by resistance. The operational amplifier 45 whose output terminal is connected to a power supply line by a pull-up resistor 48 compares the reference voltage with the negative voltage of the current detecting resistor 18 and supplies the result to the fourth communication circuit 13c. .

As shown in FIG. 2, the receiving circuit 52 includes a coupling capacitor 52a, a first resistor 52b, a second resistor 52c, a first transistor 52d, a third resistor 52e, a fourth resistor 52f, a second transistor 52g, Fifth resistor 5
2h, one end of the coupling capacitor 52a is connected to the power supply line A, and the other end is connected to one end of the second resistor 52c and the first transistor 52 via the first resistor 52b.
Commonly connected to the base of d. And this second
The other end of the resistor 52c is connected to the output line of the constant voltage circuit 31 together with the emitter of the first transistor 52d, and the collector is connected to the emitter of the second transistor 52g via the third resistor 52e and the fourth resistor 52f in series. Grounded. The third resistor 52e and the fourth resistor 52f
Is connected to the base of the second transistor 52g, and the collector of the second transistor 52g is connected to the fifth transistor 52g.
It is connected to the output line of the constant voltage circuit 31 via the resistor 52h and to the third communication circuit 37 of the microcomputer 32 '. However, the third communication circuit 37
Is one in which the receiving function is lacking in the third communication circuit 37 in FIG.

[0016]

As described above, according to the present invention,
The effect is obtained that the configuration of the receiving circuit can be simplified, and thereby the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of an occupant protection device according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a voltage detection type receiving circuit of the side airbag unit in FIG.

FIG. 3 is an explanatory diagram of a conventional circuit block.

[Explanation of symbols]

 Reference Signs List 1 airbag unit for front collision 2 side airbag unit for driver's seat 3 side airbag unit for passenger's seat 8, 32 microcomputer 13a, 13b, 13c, 37 communication circuit 14, 15, 40, 44 switching transistor 18, 19 current Detection resistors 21, 23 Split resistors 41, 45 Operational amplifiers 42, 46 Reference voltage generating resistors 50, 51 Current detection type receiving circuit 52 Voltage detection type receiving circuit

Claims (2)

[Claims] A main microcomputer having at least a communication input / output port, which is provided with a communication input / output port, and a sub-microcomputer provided in each of the sub-occupant protection devices. A power supply line connected between the main microcomputer and the plurality of sub-microcomputers via one communication resistor in series, and a transmission circuit and a reception circuit are respectively provided on the main microcomputer side and the sub-microcomputer side of the power supply line. A circuit is connected, the power supply line is shared as a signal line, and each of the main microcomputer and the sub-microcomputer performs multiplex communication via the power supply line. The receiving circuit is of a current detection type, and Micro respective receiving circuits of the computer side, the voltage detection type and by the vehicle occupant protection apparatus, characterized by comprising. 2. The vehicle occupant protection device according to claim 1, wherein the receiving circuit on the main microcomputer side detects a current by the communication resistor connected in series to the power supply line.