JP2001233168A - Occupant constraining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably diagnose a short circuit failure without adding a circuit component to a conventional circuit and without increasing the cost. SOLUTION: In a failure diagnostic mode, a CPU 11 feeds a weak diagnostic current to a plurality of squibs DR1, DR2 respectively to self-diagnose the healthiness of the squibs based on the 'H' or 'L' of their both end voltages respectively. The CPU 11 feeds a diagnostic current to one of squib lines 15, 16 feeding power to the squibs on the downstream side or on the upstream side not connected in common to the squib line to the other squib, compares both end voltages of the squib receiving the diagnostic current and the other squib, and judges that a short circuit occurs on the squib lines when they are nearly equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an occupant restraint system having a multi-stage inflator.

[0002]

2. Description of the Related Art Conventionally, an occupant restraint system having a function of detecting the presence or absence of an occupant seated in a seat and the presence or absence of a child seat, and adjusting the deployment pressure of an airbag based on the presence or absence of the occupant and the occupant position. It has been known.

In this conventional occupant restraint system, two inflators are provided to adjust the deployment pressure of the airbag, and based on the occupant presence / absence and the occupant position, whether the two are inflated simultaneously (full deploy mode), It is configured to switch between the deployment with a time difference (tailored deployment mode) and the non-deployment (cut-off mode). (In this specification, two deployments with such a deployment pressure adjustment function are provided.) The inflator is referred to as a "dual stage inflator," and more generally, a plurality of inflators provided with an airbag deployment pressure adjusting function are referred to as a "multi-stage inflator."

In an occupant restraint system having such a dual stage inflator, the upstream or downstream side of the squib line for the two squibs is commonly connected in order to reduce the number of circuit components.

Conventionally, the occupant restraint system has a self-diagnosis function of executing a self-diagnosis of the system at the time of starting the system and displaying a warning light when a failure is diagnosed.

[0006]

However, in a conventional occupant restraint system having a dual stage inflator,
There were the following problems. That is, in the squib line for each of the two squibs, if the downstream sides or the upstream sides that are not commonly connected are short-circuited for any reason, first, in order to deploy the airbag in the tailored deployment mode described above, first, When the air bag is deployed by the squib in the first stage, the deployment current flows also in the squib in the second stage due to the short circuit, so that the two inflators are simultaneously operated and the air bag is fully deployed as described above. It will be deployed in the mode, and cannot be deployed at the desired pressure.

In order to avoid this, it is conceivable to provide a dedicated detection circuit for detecting a short circuit of the squib lines of a plurality of squibs. However, this inevitably results in a significant increase in cost.

The present invention has been made in view of such a conventional problem, and a short circuit failure can be diagnosed reliably without increasing a cost by not adding a circuit component to a conventional circuit. An object of the present invention is to provide an occupant restraint device having a function.

[0009]

According to the first aspect of the present invention, there is provided a multi-stage inflator having a plurality of squibs, and adjusting the deployment pressure of the airbag by energizing the squibs simultaneously or with a time difference. An upstream or downstream side of the squib line for supplying power to each of the plurality of squibs is commonly connected, and in the occupant restraint device including a self-diagnosis circuit for diagnosing the presence or absence of a failure in each of the squibs, the self-diagnosis circuit includes: In one of the squib lines for supplying power to the plurality of squibs, a diagnosis current is supplied to a downstream side or an upstream side that is not commonly connected to the squib line for another squib, and a diagnosis is performed in a state where the diagnosis current is supplied. Compare the voltage between the squib carrying the current and the other squib. Serial to a plurality of squibs lines in which it is determined that the short circuit has occurred.

According to a second aspect of the present invention, there is provided the occupant restraint system according to the first aspect, further comprising a warning light that is turned on when the self-diagnosis circuit determines that a failure has occurred.

[0011]

According to the occupant restraint system of the first aspect of the present invention, the self-diagnosis circuit includes a squib line for supplying power to a plurality of squibs, the squib line for the other squib being not connected to the squib line for the other squib. The diagnostic current is supplied to the squib, and while the diagnostic current is supplied, the voltage at both ends of the squib carrying the diagnostic current is compared with that of another squib. Is determined to have occurred.

[0012] With this configuration, by using the conventional self-diagnosis circuit, the voltage between the squib of one squib line and the squib of the other squib line is checked while the diagnostic current is being supplied to one squib line, and the squib is checked. A short circuit fault between lines can be determined. Therefore, a short-circuit failure can be diagnosed without adding a circuit component or a dedicated circuit to the conventional circuit for diagnosing the short-circuit failure.

In the occupant restraint system according to the second aspect of the invention, in addition to the effect of the first aspect, the warning light is turned on when a failure is determined, so that the diagnosis result can be immediately recognized.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 1 shows a system configuration according to an embodiment of the present invention. The center unit 10
The CPU 11 shown in FIG. 2 is built in, an acceleration signal is taken in from the G sensor 12, and a predetermined calculation is performed to determine whether or not an impact that needs to deploy the airbag to protect the occupant of the vehicle has occurred. (This determination method is not particularly limited. For example, JP-A-07-07
The method described in Japanese Patent No. 6256 can be adopted). Also, the presence / absence of occupants, occupant position signals, etc. are taken in from the occupant detection device 13 installed in each of the driver's seat and the passenger's seat, and the driver's seat and the passenger's seat are each used. The airbag deployment mode is selected depending on whether the position of the occupant from the airbag outlet immediately before the deployment of the airbag is within the distance range where the airbag can be deployed at high speed and full pressure. Perform deployment control.

The first-stage squib (D) is provided in the driver airbag module embedded in the steering wheel.
A squib # 1) 21 and a second-stage squib (D squib # 2) 22 are provided. The first-stage squib (A. squib # 1) 23 and the second-stage squib (A. squib # 2) are contained in the passenger seat airbag module embedded in the instrument panel on the passenger seat side.
24 are provided. A warning lamp 25 for failure diagnosis is provided in the instrument panel.

FIG. 2 shows a detailed internal configuration of the center unit 10. The center unit 10 is a CPU 11
And a squib line 15 of the first stage and a squib line 16 of the second stage in which the downstream sides are commonly connected. The configuration of the center unit 10 is a CP
Apart from the program incorporated in U11, it is the same as the conventional configuration. Although only the passenger seat side is shown in FIG. 2, the driver seat side has the same configuration as the common CPU 11. The first-stage squib line 15 includes a first-stage squib DR1 and a first-stage upstream drive transistor TR1 that receives an ignition instruction from the CPU 11 and injects an ignition current into the first-stage squib DR1. 1
A downstream drive transistor T for guiding the ignition current injected from the upstream drive transistor TR1 of the stage to the ground
R3 is provided. The first-stage squib line 15 further includes a first-stage diagnostic transistor TR11 provided in parallel with the upstream-side driving transistor TR1, and a downstream-side diagnostic transistor TR31 provided in parallel with the downstream-side driving transistor TR3. Have been.

The second-stage squib line 16 includes a second-stage squib DR2 and a second-stage upstream-side driving transistor TR2 for receiving an ignition instruction from the CPU 11 and injecting an ignition current into the second-stage squib DR2. Are provided.
The second stage squib line 16 further includes a second stage diagnostic transistor TR21 with an upstream drive transistor T
It is provided in parallel with R2. The downstream drive transistor TR3 and the diagnostic transistor TR31 that guide the ignition current of the second stage to the ground are both common to the squib line 15 of the first stage.

The above diagnostic transistors TR11, TR
21 and TR31, the driving transistor TR
A resistor is connected so that a weak diagnostic current flows with respect to the ignition current flowing through each of the first, TR2 and TR3.

OP1 and OP2 are operational amplifiers for amplifying the potential difference between both ends of the squibs provided on the first and second squib lines 15 and 16 and outputting the amplified signals to the terminals (7) and (9) of the CPU 11, respectively. is there.

The squib DR1 in the first stage and the squib DR2 in the second stage are red-hot when an ignition current is supplied, and function to deploy the airbag by igniting the gas generating agent. Under the control of the CPU 11, the first-stage squib DR1 and the second-stage squib DR
2 at almost the same time (that is, in the full deployment mode) to rapidly inflate the airbag at all pressures, and operate with a time difference between the first squib DR1 and the second squib DR2. (Ie, in the tailored deploy mode) to reduce the inflation rate of the airbag. Next, the operation of the occupant restraint device having the above configuration will be described. First, the deployment operation of the airbag will be described. CPU 11 in center unit 10
Repeatedly checks the acceleration signal from the G sensor 12 at a high-speed cycle to determine whether or not a collision that requires the deployment of the airbag has occurred. The CPU 11 also determines the presence or absence of the occupant and the occupant position based on a signal from the occupant detection device 13,
According to this, it is determined whether the mode is the full deploy mode, the tailored deploy mode, or the cutoff mode.

When it is determined from the signal of the G sensor 12 that a collision requiring deployment of the airbag has occurred, and at the same time it is determined from the signal from the occupant detection device 13 that the vehicle is in the full deployment mode or the tailored deployment mode, From (6) and (8), the "L" signal is applied to the bases of the upstream drive transistors TR1 and TR2 simultaneously or with a time difference depending on the mode to turn them on, and at the same time, the "H" signal is supplied to the downstream drive transistor TR3. Give and turn on. As a result, the ignition current is supplied to the first-stage squib line 15 and the second-stage squib line 16, and
The squibs DR1 and DR2 in the first and second stages are glowed red to deploy the airbag at full pressure or moderate pressure.

Next, the self-diagnosis function of the occupant restraint device will be described. The flowcharts of FIGS. 3 and 4 are C
9 shows a self-diagnosis process executed by the PU 11. This flowchart starts when power is supplied to the center unit 10 by an ignition key (not shown).

First, the voltage of the first stage upstream line is detected from the terminal (1) in a state where no current flows through the squib line (step S1). When the detected voltage value is “H”, it is considered that a power short-circuit has occurred on the upstream side of the scribe line 15 of the first-stage squib DR1,
Proceeding to step S31, the warning lamp 25 is turned on (branch to YES in step S2). If the voltage value detected in step S1 is "L", it is determined that there is no abnormality and the next step S3
Proceed to.

In step S3, the voltage of the second-stage upstream line is detected from the terminal (2) in a state where no current flows through the second-stage squib line 16. If the detected voltage value is “H”, it is considered that a power short-circuit has occurred on the upstream side of the scribe line 16 of the second-stage squib DR2, and the process proceeds to step S31 to turn on the warning lamp 25 (step S31). (Branch to YES in S4). When the voltage value detected in step S3 is "L", it is determined that there is no abnormality and the process proceeds to the next step S5.

In step S5, the voltage of the common downstream line is detected from the terminal (3) in a state where current does not flow through both the squib lines 15 and 16. If the detected voltage value is "H", it is considered that a power supply short circuit has occurred in this line, and the process proceeds to step S31, where the warning light 2
5 is turned on (branch to YES in step S6). If the voltage value detected in step S5 is "L", it is determined that there is no abnormality and the process proceeds to the next step S7.

In steps S7 to S10, a voltage is applied to the common downstream line from the terminal (4), and then a voltage is applied to the terminal (5).
"H" to the base of the downstream drive transistor TR3
And drives the same, detects the voltage of the common downstream line from the terminal (3), and detects the detected voltage value “H”,
"L" is determined.

If "H" is determined in step S10, it is considered that the downstream drive transistor TR3 is out of order, and the process proceeds to step S31, where the warning lamp 25 is activated.
Is turned on (branch to YES in step S10). When it is determined to be “L” in step S10, it is determined that there is no abnormality, and the process proceeds to the next step S11.

In steps S11 to S13, the terminal (6)
Input "L" to the base of the first-stage upstream drive transistor TR1 to drive the transistor, detect the voltage of the first-stage upstream squib line 15 from the terminal (1), and detect the detected voltage value. "H" and "L" are determined.

If it is determined as "L" in step S13, the first-stage upstream-side driving transistor TR
1 is considered to be faulty, the process proceeds to step S31, and the warning light 25 is turned on (branch to YES in step S13). If "H" is determined in step S13, it is determined that there is no abnormality, and the process proceeds to the next step S14.

In steps S14 and S15, the terminal (1
From "0", "L" is input to the base of the upstream diagnostic transistor TR11 in the first stage to drive it, and subsequently "H" is input from the terminal (12) to the base of the downstream diagnostic transistor TR31. By driving this, a weak current flows through the squib line 15 of the first stage. Then, in steps S16 and S17, the voltage of the common downstream line is detected, and "H" and "L" of the detected voltage value are determined.

If "L" is determined in step S17, it is assumed that the first squib line 15 is disconnected, and the flow advances to step S31 to turn on the warning lamp 25 (YES in step S17). Branch). Step S
If it is determined to be "H" in step 17, it is determined that there is no abnormality and the process proceeds to step S18.

In steps S18 and S19, in order to detect the resistance value of the squib DR1 in the first stage, the voltage of the squib DR1 is changed while the upstream diagnosis transistor TR11 and the common downstream diagnosis transistor TR31 are turned on. The resistance value is calculated by detecting from the output voltage of the operational amplifier OP1 at the terminal (7), and it is determined whether the resistance value of the squib DR1 is within a predetermined range.

If the resistance value of the first-stage squib DR1 is not within the predetermined range in step S19, the squib DR1 has a resistance value that does not generate heat enough to expand the inflator, or is abnormal because the resistance is too high. Assuming that there is, the process proceeds to step S31, and the warning light 25 is turned on (branch to YES in step S19). If the resistance value of the squib DR1 is within the predetermined range in step S19, it is determined that there is no abnormality, and the process proceeds to step S20.

In step S20, the output of the operational amplifier OP2 is input from the terminal (9), and the voltage value is detected. In the following step S21, the voltage value of the terminal (7) and the voltage value of the terminal (9) detected for calculating the resistance value of the first squib DR1 in step S18 are compared. In the comparison of the voltage values, the determination is made as follows.

The upstream side of the first stage squib line 15
If a short circuit occurs with the upstream side of the squib line 16 of the first stage, a weak current flowing through the upstream-side diagnostic transistor TR11 of the first stage will cause both of the squib lines 15,
16, the voltages of the squibs DR1 and DR2 are substantially equal, and the voltages of the squibs DR1 and DR2 are different if the short-circuit failure does not occur.

Therefore, in the comparison of the voltage values in step S21, if the output voltages of OP1 and OP2 are equal, it is determined that a failure has occurred, and the flow advances to step S31 to turn on the warning lamp 25. However, if the output voltages of OP1 and OP2 are different, it is determined that there is no abnormality, and the process proceeds to step S22.

In steps S22 to S24, the terminal (8)
Input "L" to the base of the second-stage upstream drive transistor TR2 to drive it, detect the voltage of the second-stage upstream squib line 16 from the terminal (2), and detect the detected voltage value. "H" and "L" are determined.

If "L" is determined in step S24, the second-stage upstream drive transistor TR
2 is considered to be faulty, the process proceeds to step S31, and the warning light 25 is turned on (YES in step S13). If "H" is determined in step S24, it is determined that there is no abnormality and the process proceeds to the next step S25.

In steps S25 and S26, the terminal (1
"L" is input to the base of the upstream diagnostic transistor TR21 in the second stage from 1) to drive it, and "H" is subsequently input from the terminal (12) to the base of the downstream diagnostic transistor TR31. By driving the squib line, a weak current flows through the second squib line. Then, in steps S27 and S28, the voltage of the common downstream line is detected, and "H" and "L" of the detected voltage value are determined.

If "L" is determined in step S28, it is considered that a disconnection has occurred in the second squib line, and the flow advances to step S31 to turn on the warning lamp 25 (YES in step S28). ). Step S28
If it is determined to be "H" in step S29, it is determined that there is no abnormality, and the process proceeds to step S29.

In steps S29 and S30, in order to detect the resistance value of the squib DR2 in the second stage, the voltage of the squib DR2 is changed while the upstream diagnosis transistor TR21 and the common downstream diagnosis transistor TR31 are kept on. The resistance value is calculated by detecting the output voltage of the operational amplifier OP2 at the terminal (9), and it is determined whether the resistance value of the squib DR2 is within a predetermined range.

If the resistance value of the second-stage squib DR2 is not within the predetermined range in step S30, the squib DR2 has a resistance value that cannot generate heat enough to expand the inflator, or is too high to be abnormal. Assuming that there is, the process proceeds to step S31, and the warning light 25 is turned on (branch to YES in step S30). If the resistance value of the squib DR2 is within the predetermined range in step S30, it is determined that there is no abnormality, and the series of self-diagnosis routines ends.

As described above, according to the self-diagnosis function of the occupant restraint system of the present embodiment, the squib D of the first and second stages can be used without changing the circuit configuration similar to the conventional one.
Diagnosis of the presence / absence of a failure in R1 and DR2, diagnosis of the presence / absence of a power short-circuit in the first-stage and second-stage upstream squib lines 15, 16 and diagnosis of the presence / absence of a short-circuit in the common downstream squib line Due to a slight change in the self-diagnosis program incorporated in the CPU 11, especially in step S2
The diagnosis of short-circuit failure of the first and second upstream squib lines 15 and 16 can be performed only by adding the processes of 0 and S21, and this diagnosis can be performed without providing a dedicated circuit and therefore increasing the cost. Become so.

In the above embodiment, the upstream squib lines of the first stage and the second stage are separated and the downstream line is made common. Conversely, the upstream squib lines are connected in common. The present invention can be similarly applied to a circuit configuration in which the downstream squib line is separated into a first stage and a second stage. Although the case of the dual-stage inflator has been described, the present invention can be similarly applied to three or more multi-stage inflators.

Further, in the above-described embodiment, the processing of the flowcharts shown in FIGS. 3 and 4 is performed only at the time of startup. However, the above processing is performed not only at the time of startup but also at predetermined time intervals. Is also good.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a center unit in the embodiment.

FIG. 3 is a first half of a flowchart of a self-diagnosis process executed by a CPU in the embodiment.

FIG. 4 is an intermediate part of the above flowchart.

FIG. 5 is the second half of the above flowchart.

[Explanation of symbols]

 Reference Signs List 10 center unit 11 CPU 12 G sensor 13 occupant detection device 15 first-stage squib line 16 second-stage squib line TR1 first-stage upstream drive transistor TR2 second-stage upstream drive transistor TR3 downstream drive Transistor TR11 First stage upstream diagnostic transistor TR21 Second stage upstream diagnostic transistor TR31 Downstream diagnostic transistor OP1 Operational amplifier OP2 Operational amplifier

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3D054 AA02 AA03 AA13 AA14 DD28 EE10 EE11 EE14 EE28 EE29 EE30 EE31 EE39 EE48 EE49 EE57 FF15

Claims (2)

[Claims] 1. A multi-stage squib having a multi-stage inflator for adjusting a deployment pressure of an airbag by energizing the squibs simultaneously or with a time difference, and supplying power to each of the plurality of squibs. An upstream or downstream side of the squib line is commonly connected, and in the occupant restraint device including a self-diagnosis circuit for diagnosing the presence or absence of a failure in each of the squibs, the self-diagnosis circuit includes a squib line for supplying power to the plurality of squibs. In one of the squibs, a diagnostic current is supplied to a downstream side or an upstream side that is not commonly connected to a squib line for another squib. And if the voltages are almost the same, a short circuit occurs in the plurality of squib lines. Occupant restraint system, characterized in that to determine that none. 2. The occupant restraint system according to claim 1, further comprising a warning light that is turned on when the self-diagnosis circuit determines that a failure has occurred.