JPH11348715A - Collision determining device for occupant protecting system in vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption by setting low voltage in a sensor side unit and a control side unit by performing transceiving through a wire between the sensor side unit and the control side unit by a current change signal. SOLUTION: Collisoin is determined based on the detection output of an acceleration sensor 110 by a microcomputer 120, and as a result, a changed current is carried in a wire 300 from a transceiving circuit 130 in the case of termination of collision, in a sensor side unit 100. In a control side unit 200, collision is determined by detecting the changed current from the sensor side unit 100 in a transceiving circuit 220, to drive an occupant protecting mechanism 420 by operating a drive circuit 410. Since bi-directional each signal transceiving it thus performed between both the sensor side unit 100 and control side unit 200 by the change of the current, a voltage change when a signal is transceived ca be very small generated. Accordingly, operating voltage of the sensor side unit 100 and control side unit 200 can be set low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an occupant protection system such as an airbag system for a vehicle, and more particularly to a collision determination device suitable for determining whether or not a collision has occurred in an occupant protection system.

[0002]

2. Description of the Related Art Conventionally, in this type of collision judging device, the presence or absence of a collision of the vehicle is judged by comparing the acceleration of the vehicle with a predetermined threshold value. Is designed to protect.

[0003]

By the way, in the above-mentioned collision judging device, the judgment of the collision of the vehicle is made by exchanging various signals. However, since this signal exchange is performed with a change in voltage, loss of electric energy as a collision determination device is large.

[0004] In order to cope with such a problem, the present invention provides a collision judging device in a vehicle occupant protection system, which judges whether a vehicle has collided by using a change in current. The purpose is to do.

[0005]

In order to solve the above problems, according to the first to third aspects of the present invention, a collision judging device for a vehicle occupant protection system comprises: a sensor unit (100); A control unit (200) connected to the sensor unit via the wiring (300).

The sensor unit detects an acceleration of the vehicle and generates an acceleration signal.
A collision judging means (520, 530, 540) for judging the presence or absence of a collision of the vehicle based on the acceleration signal and outputting a collision occurrence signal at the time of judging the collision; And a sensor-side transmitting / receiving means (130) for transmitting as a signal.

When the control-side unit transmits a control-side current change signal necessary for transmission / reception to / from the sensor-side transmission / reception means through the wiring to the sensor-side transmission / reception means, the control-side unit transmits the signal from the sensor-side transmission / reception means through the wiring Control-side transmitting / receiving means for receiving a sensor-side current change signal (210, 220)
And control means (630, 650) for performing control for operating the occupant protection device of the occupant protection system based on the sensor-side current change signal received by the control-side transmission / reception means.

As described above, since the transmission and reception via the wiring between the sensor side unit and the control side unit are performed by the current change signal, the voltages in the sensor side unit and the control side unit can be set low. As a result, power consumption can be reduced. Here, according to the second aspect of the present invention, the control-side transmitting / receiving means has a power supply (210), and the voltage of this power supply is superimposed on the transmission / reception of each of the current change signals through a wiring. Done.

[0009] Even when superimposed in this way, since the voltage is low,
The power supply voltage can be supplied in a stable state. Further, the current change signal may be a digital signal, as in the third aspect of the present invention.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a vehicle occupant protection system to which the present invention is applied. The occupant protection system includes a sensor unit 100, a control unit 200 connected to the sensor unit 100 via a wiring 300, and an occupant protection device 400 controlled by the control unit 200.

In the present embodiment, the sensor-side unit 100, the control-side unit 200, and the wiring 300 constitute a collision determination device of the occupant protection system. The sensor-side unit 100 includes an acceleration sensor 110, a microcomputer 120, and a transmission / reception circuit 130. The acceleration sensor 110 is provided at an appropriate position of the vehicle. The acceleration sensor 110 detects an acceleration generated in the vehicle and generates an acceleration signal in a state where the current Ic is supplied from the transmission / reception circuit 130.

The microcomputer 120 executes the sensor-side computer program according to the flowchart shown in FIG.
Based on each output of the transmission and reception circuit 10 and the transmission / reception circuit 130, processing such as collision determination of the vehicle or failure diagnosis of the sensor unit 100 is performed. Note that the microcomputer 120 operates by receiving a constant voltage from the transmission / reception circuit 130. The sensor-side computer program is stored in the ROM of the microcomputer 120 in advance.

The transmission / reception circuit 130 includes a constant voltage circuit 131 as shown in FIG.
31 is a microcomputer which generates a constant voltage and
And the current Ic is supplied to the acceleration sensor 110 based on the constant voltage. Further, the transmission / reception circuit 130
Has a voltage comparator 132 and both voltage dividers 133 and 134.

The voltage divider 133 divides a voltage Vi output from the control unit 200 through the wiring 300 as will be described later by the resistors 133a and 133b connected in series with each other. To generate a divided voltage. This divided voltage is substantially equal to the voltage Vi. On the other hand, the voltage divider 134 is connected to the constant voltage circuit 131 by the resistors 134a and 134b connected in series to each other.
, And a reference voltage (hereinafter, referred to as a reference voltage Vc) is generated from a common terminal of the resistors 134a and 134b.

The voltage comparator 132 compares the divided voltage from the voltage divider 133 with a reference voltage Vc from the voltage divider 134. The divided voltage from the voltage divider 133 is equal to the reference voltage V.
When it is lower than c, the voltage comparator 132 generates a low-level comparison signal. When the divided voltage from the voltage divider 133 reaches the reference voltage Vc, the voltage comparator 132 generates a high-level comparison signal.

The transmission / reception circuit 130 includes a constant current circuit 1
35, a current detection circuit 136, and a constant current circuit 137. In the constant current circuit 135, when the driving transistor 135a is turned on by a high-level comparison signal from the voltage comparator 132, the transistor 135c
In the on state, the current I from the constant voltage circuit 135b
o is inhaled.

Here, the transistor 135c is turned on together with the transistor 135d by turning off both transistors 135e by turning on the driving transistor 135a. The current detection circuit 136 detects the sink current Io of the constant current circuit 135 and outputs the current Io to the microcomputer 120 as a current detection signal.

In the constant current circuit 137, when the drive transistor 137a is turned on or off under the control of the microcomputer 120, both transistors 137a
b turns off or on. Thereby, the constant current circuit 13
7 permits the application of the voltage Vi from the control unit 200 to the constant current circuit 135 under the constant voltage circuit 137c when both transistors 137b are off. When both transistors 137b are on, the constant current circuit 137
Voltage V from control unit 200 to constant current circuit 135
Blocking the application of i.

As shown in FIGS. 1 and 3, the control unit 200 includes a power supply circuit 210 and a transmission / reception circuit 220.
, Microcomputer 230, alarm lamp 240
And The power supply circuit 210 has two voltages Vs and Vb.
Occurs. Here, in the power supply circuit 210, the voltage V
b is controlled so that the voltage of the anode of the diode 221 described later becomes the voltage Vba. However, in the present embodiment, it is set so that the voltage Vs> the reference voltage Vc> the voltage Vba.

As shown in FIG. 3, the transmission / reception circuit 220 includes a backflow prevention diode 221 and a constant current circuit 222.
, An analog switch 223, and a current detection circuit 224. The diode 221 supplies a current based on the voltage Vb of the power supply circuit 210 to the current detection circuit 224. The diode 221 is connected to the analog switch 22.
3 and a backflow of current from the current detection circuit 224 to the power supply circuit 210 is prevented.

The constant current circuit 222 receives the voltage Vs from the power supply circuit 210 and generates a constant current Is. However, in the present embodiment, the constant current Is is set to be higher than the current Ic, and the sum of the current Ic and the sink current Io is equal to the constant current Is.
It is set larger than. Analog switch 223
Is turned on or off under the control of the microcomputer 230. Here, the analog switch 223 supplies the constant current Is from the constant current circuit 222 to the current detection circuit 224 when turned on. The analog switch 223 shuts off the supply of the constant current Is from the current circuit 222 to the current detection circuit 224 when the analog switch 223 is turned off.

The current detection circuit 224 includes a diode 221
, Or a current from the analog switch 223 and outputs a current detection signal to the microcomputer 230. The microcomputer 230 executes the control-side computer program according to the flowchart shown in FIG. 5, and during this execution, the current detection circuit 224
Based on the output of the analog switch 223,
The drive control processing of the occupant protection device 400 and the alarm lamp 240 is performed. The control computer program is stored in the ROM of the microcomputer 230 in advance.

The wiring 300 includes a ground line 310 and a signal line 320 as shown in FIGS. 2 and 3, and the ground line 310 is connected to each ground terminal of the sensor unit 100 and the control unit 200. Have been. Signal line 320
Is connected between the output terminal of the current detection circuit 224 of the control unit 200 and the input terminal of the constant current circuit 137 of the sensor unit 100.
0 is the sensor side unit 100 and the control side unit 200
It plays a role in transmitting and receiving signals to and from.

The occupant protection device 400 includes a drive circuit 410
And an occupant protection mechanism 420.
0 is controlled by the microcomputer 230,
The occupant protection mechanism 420 is driven. Occupant protection mechanism 420
Is driven and operated by the drive circuit 410 to protect the occupants of the vehicle. In the present embodiment configured as described above, it is assumed that the vehicle is in a running state. here,
The sensor unit 100 and the control unit 200 are in the operating state, the microcomputer 120 executes the sensor computer program according to the flowchart of FIG. 4, and the microcomputer 230 executes the control computer program according to the flowchart of FIG. It is assumed that

The microcomputer 120 ends the initialization process at step 500 when its execution is started, and the microcomputer 230 also ends the initialization process at step 600 at the start of its execution. ing. At this stage, the drive transistor 137a of the constant current circuit 137 of the sensor unit 100 is in the off state, and the analog switch 223 of the control unit 200 is in the off state.
Is in the off state.

In such a state, in the microcomputer 120, when the sensor-side computer program proceeds to step 510, the detection output of the acceleration sensor 110 is input to the microcomputer 120. Next, in a collision determination routine 520, a process of determining the presence or absence of a collision of the vehicle is performed based on a detection output of the acceleration sensor 110.

Here, if it is determined in the collision determination routine 520 that the vehicle is in collision, a determination of YES is made in step 530. Accordingly, in step 540, a pulse-like collision occurrence signal indicating the occurrence of the collision of the vehicle is output to the constant current circuit 137. Therefore, the constant current circuit 137 repeatedly turns on and off the drive transistor 137a (see FIG. 6) based on the pulse-like collision generation signal, thereby turning off and on both transistors 137b, thereby controlling the control unit 200 and the sensor unit. The transmission and reception of the signal with respect to 100 are intermittently permitted.

At this time, as shown in FIG. 7, a current Ic and a current composed of the sum of Ic and Ix flow alternately in the signal line 320 in accordance with the repetition of the turning on and off of both transistors 137b. Specifically, when the collision occurrence signal is at a high level, the drive transistor 137a is turned on, and when the collision occurrence signal is at a low level, the drive transistor 137a is turned off. A current that changes as shown by the arrow flows.

When this current is detected by the current detection circuit 224 of the control unit 200 as described later, this detection current is input to the microcomputer 230 by the current detection circuit 224 as a detection signal (step in FIG. 5). 610). This means that the sensor-side unit 10
This means that signal transmission (signal transmission of a collision occurrence signal) from the 0 side to the control unit 200 side is permitted.

Here, since the voltage Vi to the sensor-side unit 100 does not change, the signal transmission and the power supply from the power supply circuit 210 to the sensor-side unit 100 can be performed via the signal line 320 at the same time. On the other hand, if the determination in step 530 is NO, a failure diagnosis routine 550 diagnoses whether there is a failure in the sensor-side unit 100.

Here, when a failure is diagnosed,
The determination in step 560 is YES, and in the next step 570, a pulse-like failure occurrence signal is output to the constant current circuit 137. Therefore, the constant current circuit 1
At 37, as in the case of the collision occurrence signal, the on / off of the drive transistor 137a (see FIG. 6) is repeated to repeatedly turn off and on both transistors 137b.
(Transmission of a failure occurrence signal) to the device.

On the other hand, if the determination in step 560 is NO
In step 580, the presence or absence of the output signal of the current detection circuit 136 is determined. Here, if there is an output signal of the current detection circuit 136, this output signal is input to the microcomputer 120 in step 590. On the other hand, in the microcomputer 230, when the control-side computer program proceeds to step 610, a process of confirming the presence or absence of the detected current output from the current detection circuit 224 is performed.

At this stage, if there is no current detected by the current detection circuit 224, the determination in step 620 is NO.
Becomes Then, in step 670, it is determined whether it is necessary to transmit a signal to the sensor-side unit 100. If necessary, the determination in step 670 is YES, and in step 680, control processing of the analog switch 223 is performed. Specifically, the analog switch 223 is turned on and off as shown by the waveform in FIG.
Controlled by 0. With this, analog switch 2
23 repeats on / off.

Therefore, the constant current Is of the constant current circuit 222
While passing through the current detection circuit 224 while changing according to the on / off repetition of the analog switch 223, the signal line 320
Flows to Thus, the constant current Is is detected by the current detection circuit 22.
4, the current detection circuit 224 generates a detection current and inputs it to the microcomputer 230. Accordingly, the determination in step 620 becomes YES.

Further, when the constant current Is of the constant current circuit 222 changes and flows through the signal line 320 as described above, the voltage Vi generated on the signal line 320 based on this changes to the power supply circuit 2.
Attempt to rise to a voltage Vs of 10. Accordingly, the voltage Vi is divided by the voltage divider 134 as a divided voltage. At this time, since the voltage Vi also changes as shown in FIG. 10 with the change in the current flowing through the signal line 320, the divided voltage of the voltage divider 134 is accordingly adjusted.
Or lower than the reference voltage Vc. Therefore, the voltage comparator 1
The 32 comparison signals alternate between a high level and a low level.

With the change of the comparison signal, the constant current circuit 1
The 35 drive transistors 135a are repeatedly turned on and off as shown in FIG. Therefore, the constant current circuit 135
, The sink current Io is generated intermittently in the transistor 135c, and the current detection circuit 136 generates the current detection signal as described above. The sum of the current Ic flowing through the acceleration sensor 110 and the sink current Io is determined by the constant current circuit 22.
When the current becomes larger than the constant current Is from the signal line 32,
The divided voltage generated in the voltage divider 134 based on the voltage Vi of 0 is fixed to the reference voltage Vc (see FIG. 10).

As described above, when the control-side computer program reaches step 620, and a determination of YES is made, in step 630, the presence or absence of a collision occurrence signal from the sensor-side unit 100 is determined. This determination is made based on the presence or absence of a change current flowing through the signal line 320 in accordance with a change in the current of the constant current circuit 137 based on the collision occurrence signal.

Here, as described above, if the current flowing through the signal line 320 changes as shown in FIG. 7 based on the collision occurrence signal from the microcomputer 120, the determination in step 630 becomes YES. Then, in the next step 650, drive processing of the drive circuit 410 is performed. As a result, the drive circuit 410 drives the occupant protection mechanism 420 to protect the occupant.

If the determination in step 630 is NO
In step 640, the presence or absence of a failure occurrence signal from the sensor unit 100 is determined. This determination is based on the constant current circuit 137 based on the failure occurrence signal.
This is determined by the presence or absence of a change current flowing through the signal line 320 in accordance with the current change. Here, as described above, the signal line 320
Is changed based on the failure occurrence signal from the microcomputer 120, the determination in the step 640 becomes YES.

Next, at step 660, an alarm process is performed, and accordingly, the alarm lamp 240 is turned on to issue an alarm. Thus, occurrence of a failure in the sensor unit 100 can be known. As described above, the sensor unit 100 and the control unit 200
Since both signal transmissions in both directions are performed with a change in current, the voltage change during the signal transmission can be made very small.

Thus, the voltage for operating the sensor unit 100 and the control unit 200 as a whole can be set low. This means that the power loss can be reduced by lowering the operating voltage of the entire occupant protection system. Further, since the voltage can be set low as described above, the change in the voltage is small. Therefore, even when the voltage of the power supply circuit 210 and the signal are superimposed, the voltage of the power supply circuit 210 can be supplied as a stable voltage through the signal line 320. As a result, the sensor-side unit 10
0 and the operation of each element in the control side unit 200 can be stabilized.

In practicing the present invention, circuits shown in FIGS. 11 and 12 may be employed in place of the constant current circuits 137 and 135 described in the above embodiment. . Further, in implementing the present invention, each current change signal described in the above embodiment may be a digital signal.

In practicing the present invention, the occupant protection system described in the above embodiment includes an airbag system and a belt tensioner of the vehicle.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of the sensor-side unit of FIG.

FIG. 3 is a detailed circuit diagram of a control unit of FIG. 1;

FIG. 4 is a flowchart showing the operation of the microcomputer of the sensor-side unit.

FIG. 5 is a flowchart showing the operation of the microcomputer of the control-side unit.

FIG. 6 is a timing chart showing an on / off operation of a driving transistor 137a.

FIG. 7 is a timing chart showing a change in a current flowing through a signal line 320.

FIG. 8 is a timing chart showing an on / off operation of the analog switch 223.

FIG. 9 is a timing chart showing an on / off operation of a driving transistor 135a.

FIG. 10 is a timing chart showing a change state of a voltage Vi generated in a signal line 320.

FIG. 11 is a circuit diagram showing a modification of the embodiment.

FIG. 12 is a circuit diagram showing another modification of the embodiment.

[Explanation of symbols]

100: sensor side unit, 110: acceleration sensor, 1
20, 230 ... microcomputer, 130, 220
... Transceiver circuit, 200 ... Control unit, 210 ... Power supply circuit, 300 ... Wiring, 320 ... Signal line, 400 ... Occupant protection device.

Claims (3)

[Claims] 1. A sensor-side unit (100) provided in a vehicle occupant protection system, and a control-side unit (200) provided in the occupant protection system and connected to the sensor-side unit via a wiring (300). The sensor-side unit includes: an acceleration sensor (110) that detects an acceleration of the vehicle and generates an acceleration signal; and determines whether or not the vehicle has a collision based on the acceleration signal. A collision determination unit (520, 530, 540) that outputs a signal; and a sensor-side transmission / reception unit (130) that transmits the collision occurrence signal as a sensor-side current change signal through the wiring. Transmitting a control-side current change signal required for transmission / reception to / from the sensor-side transmission / reception means to the sensor-side transmission / reception means through the wiring The control-side transmission / reception means (210, 220) receiving the sensor-side current change signal from the sensor-side transmission / reception means through the wiring, and the occupant protection based on the sensor-side current change signal received by the control-side transmission / reception means. A collision determination device for a vehicle occupant protection system, comprising: a control unit (630, 650) for performing control for operating an occupant protection device of the system. 2. The control-side transmitting / receiving means includes a power supply (21
2. The vehicle occupant protection system according to claim 1, wherein the voltage of the power supply is superimposed on transmission and reception of each of the current change signals through the wiring. Collision determination device. 3. The collision judging device for a vehicle occupant protection system according to claim 1, wherein the current change signal is a digital signal.