JPH05270351A - Air bag device - Google Patents

Abstract

PURPOSE:To develop an air bag at the optimum timing responding to the seating position of a passenger. CONSTITUTION:When it is decided by a collision deciding circuit 6 that a vehicle has made collision, a timing control circuit 15 determines the seating position of a passenger and a time Tb passing from deceleration occasioned by collision to arrival of a passenger at a given buffering position. A time Ta during which an air bag 12 is developed to a given position is subtracted. By generating a development signal to the air bag 12 when a time Tb-Ta elapses starting from a time of point when the occurrence of collision is decided, the air bag 12 is developed at the optimum timing responding to the seating position of a passenger. Further, when the tie Tb-Ta is negative, a development signal is outputted approximately simultaneously with decision of the occurrence of collision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air bag device for inflating an air bag at an optimum timing according to a seating position of an occupant.

[0002]

2. Description of the Related Art In order to reduce occupant deaths due to vehicle collisions, it is urgent to introduce an airbag system that protects a driver sitting in the front seat or a driving assistant from the impact of the collision.
For example, in the airbag device on the driver's side, the airbag is embedded in the central portion of the steering wheel of the vehicle,
An impact sensor that closes the contacts when the vehicle receives an impact exceeding a certain limit due to a collision emits a deployment signal, and an operating current is supplied to a detonator element called a squib to explode the airbag explosively. .. The deployed airbag intervenes between the steering wheel and the driver to perform a cushioning function, but it usually takes about 30 ms to deploy the airbag. For example, the vehicle collides during high-speed or medium-speed traveling. When you do, the occupant will be 1 from the back of the seat.
An appropriate design considering the deployment time of the airbag is required so that the airbag receives it when it leans forward by about 2.5 cm.

However, in reality, there are individual differences in seating positions and driving postures. For this reason, when the impact sensor determines that a vehicle has collided, it may have issued a deployment signal at the same time, so if the impact sensor detects that the vehicle has collided, the vehicle will move away from the steering wheel. Since the occupant who has been operating in such a manner is buffered in a state in which the airbag is fully deployed, the cushioning effect of the airbag is less than that in the case where the airbag is cushioned in a state in which the deployment margin remains. On the other hand, when the deployment signal is issued after a certain period of time from the collision determination, the airbag cannot be fully deployed when the vehicle collides with an occupant having a driving posture close to the steering wheel. Since the passengers will be accepted as they are, there is a problem that a good cushioning effect cannot be expected. Therefore, based on these circumstances, for example,
No. 81152 "Airbag Device", the seating position of the occupant is detected by a seat slide position sensor and a seatbelt wearing sensor, and the control unit variably controls the size of the airbag deployment shape according to the seating position. Thus, a so-called adaptive airbag device has been proposed which enables an optimum cushioning effect to be obtained regardless of the seating position.

[0004]

The conventional adaptive air bag system described above has a structure in which the size of the deployed shape of the air bag is variably controlled according to the seating position, but the seating position of the occupant is directly detected. Therefore, even if the seat slide position and the extension of the seat belt are the same, there is a problem that it is difficult to be accurate depending on the physique of the occupant and the inclination angle of the backrest. That is, for example, if an obese occupant takes a driving posture with the seat itself sliding forward and the backrest tilted backward, the control unit estimates the distance from the steering wheel to the occupant shorter than it actually is. As a result, the expanded shape of the airbag is suppressed to a small size, and there is a problem that a sufficient cushioning effect cannot be obtained when a collision occurs.
Although it is held by the seat belt, the occupant leans forward with a deceleration, which is a negative acceleration, due to the impact received at the time of a collision, but without considering such forward movement of the occupant, just before the collision. Since the deployment shape of the airbag is controlled only by the seating position, there is a problem that the optimum cushioning effect cannot be expected when the position where the occupant abuts on the airbag changes due to the strength of the impact.

In addition to the above, for example, Japanese Patent Laid-Open No. 2-60
As seen in No. 858 "Vehicle Airbag Device",
There is also known an airbag device in which the deployment speed of the airbag is switched instead of the deployment shape of the airbag.
However, this one also does not consider the forward movement of the occupant according to the strength of the impact at the time of the collision, so it cannot be said that the airbag deployment speed is controlled only by the seating position before the collision, In addition, the airbag deployment speed control also depends on the seating position because the valve opening provided in the middle of the flow path for feeding gas to the airbag is only switched in several steps according to the output of the seating position sensor. The fine control was difficult, and there was a problem that there was a problem in accuracy. Furthermore, since this airbag device is configured to detect the seated state of the occupant by using an infrared sensor as a proximity switch, it is a special case that the occupant holds a large baggage or a child stands in front of the occupant. There is a limit that it is possible to detect different seating states separately from other seating conditions, and for occupants who are normally seated, there is a constraint that the seating position cannot be finely discriminated unless seated extremely close to the steering wheel. Met.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a collision determination means for determining that a vehicle has collided and a collision determination signal from the collision determination means are used to seat a passenger. When the time required for the occupant to reach a predetermined buffer position is estimated from the position and the deceleration due to the collision, and the time obtained by subtracting the time required for the airbag to deploy to the predetermined buffer position from this estimated time And a deployment signal generating means for generating a deployment signal for the airbag.

[0007]

According to the present invention, when the collision determining means determines that the vehicle has collided, the deployment signal generating means which has received the collision determining signal determines that the occupant is predetermined from the seating position of the occupant and the deceleration associated with the collision. Estimate the time to reach the buffer position, when the time after subtracting the time required for the airbag to deploy to the predetermined buffer position from this estimated time,
By generating a deployment signal for the airbag, the airbag is deployed at the optimum timing according to the seating position of the occupant.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. 1 is a circuit block diagram showing an embodiment of an airbag device of the present invention, FIG. 2 is a circuit configuration diagram of the collision determination circuit shown in FIG. 1, and FIG. 3 is used for the arithmetic circuit shown in FIG. Figure showing the collision determination map, Figure 4
FIG. 3 is a signal waveform diagram of each part of the circuit shown in FIG. 1.

The airbag apparatus 1 shown in FIG. 1 converts the acceleration signal obtained by the acceleration sensor 2 into digital data by AD conversion and performs all processing as discrete value data. As the acceleration sensor 2, a semiconductor acceleration sensor in which a stress strain gauge is formed on a semiconductor substrate is used. A stress strain gauge that utilizes the fact that the piezo resistance of a semiconductor changes when stressed and strained It is assembled with the pressure receiving surface facing the traveling direction. Before the output of the acceleration sensor 2 is converted into discrete value data, first, the acceleration signal is band-limited in the low-pass filtering circuit 3 for eliminating the influence of aliasing distortion, and subsequently, the opening / closing which operates in synchronization with the sampling clock is performed. It is supplied to the AD converter 5 via the switch 4 and converted into digital data with a predetermined quantization bit. The acceleration data G (k) obtained from the AD converter 5 is supplied to the collision determination circuit 6 and the movement distance estimation circuit 7.

As shown in FIG. 2, the collision judging circuit 6 shown in the embodiment judges the collision by simultaneously performing offset integration and impact force calculation in parallel. The offset integration is performed by the successive addition type offset integrator 8, and sampling is performed by subtracting the offset data Go indicating the maximum value of the acceleration signal generated during normal traveling from the discrete-valued acceleration data G (k). It is done by adding in time with the clock. That is, the speed change amount ΔV (k) obtained by the offset integration is calculated as ΔV (k) = Σ [G (k) −Go]. For this reason, the maximum value of the acceleration applied to the vehicle during normal traveling can be excluded from the integration target as an offset, and the amount of speed change continues to accumulate due to vibration received from a bad road during normal traveling, or It is possible to eliminate, over a considerable range, factors that are likely to make the collision determination erratic, such as a sudden speed change that a vehicle receives when riding on a curb. Further, since the steady error that the acceleration sensor 2 itself has as an individual difference can be included in the offset, the operation compensation of the measurement system is also possible.

On the other hand, the impact force calculation is performed by first extracting the band component of 100 Hz to 400 Hz included in the acceleration data in the band-pass filter circuit 9 and then performing the square calculation in the square calculator 10. Here, regarding a plastic collision in which the occupant is injured when the vehicle collides, the front part of the vehicle is regarded as a plastic spring composed of innumerable spring bodies, and the acceleration signal of the acceleration signal It is possible to extract a specific band component that shows a remarkable change at the time of a collision from various vibration waveforms superimposed on the basic 1/4 sine wave. That is, 100 of the acceleration data
The band components from Hz to 400 Hz show a unique frequency distribution for each vehicle type, but it is known that they show a large change depending on the severity of the collision, that is, the magnitude of the impact. Therefore, pay attention to these band components. Thus, it is possible to detect an impact force that cannot be understood only by tracking the speed change amount.
In addition, since the square calculator 10 squares the band component that changes between positive and negative, it is possible to accurately grasp the magnitude of the impact force regardless of whether the acceleration is positive or negative. For this reason, it is possible to determine that the collision requires the operation of the airbag 12 by distinguishing it from a shock caused by traveling on a bad road, riding on a curb, or the like through a calculation in a calculation circuit 11 described later.

The arithmetic circuit 11 makes a collision judgment according to the collision judgment map shown in FIG. The collision determination map draws a determination curve that divides the collision area and the non-collision area on a plane having two axes of impact force ΔE (k) and speed change amount ΔV (k), and the determination curve is a boundary. The collision is judged. The judgment curve shown in the drawing is composed of a polygonal line composed of three straight lines, and when the calculation in the calculation circuit 11 satisfies any one of the following three conditions, a collision judgment signal is immediately output. .. 1) ΔE (k) <E1 and ΔV (k)> V2 2) E1 <ΔE (k) <E2 and ΔE (k) / E3 +
ΔV (k) / V3> 13 3) ΔE (k)> E2, and ΔV (k) <V1 In the collision determination map shown in FIG. 3, the front collision at medium speed and the front collision at high speed are shown. In addition, the impact force ΔE is detected in each case such as a collision with a cushion drum made of a can-shaped body having a cushioning function and a collision with a pole such as a utility pole or a pole.
Regions where the correlation between (k) and the speed change amount ΔV (k) is deepest are shown surrounded by dotted lines. Further, in the area inside the determination curve, there is a case in which the arithmetic circuit 10 determines that the operation circuit 10 is not in a collision, such as an undercarriage or a bad road traveling, which indicates a collision without danger in only the chassis portion of the vehicle body. Also, impact force ΔE (k) and speed change amount ΔV
Regions with the deepest correlation of (k) are shown by enclosing them with dotted lines.

By the way, the airbag apparatus 1 has an ultrasonic sensor 13 incorporated in an appropriate portion of the dashboard facing the seat in order to detect the sitting position of the occupant. The ultrasonic sensor 13 includes an ultrasonic transmitter 13a that transmits ultrasonic waves and an ultrasonic receiver 13b that receives the ultrasonic waves reflected by the target object and returned, and the ultrasonic transmitter 13a is a seat. It is installed towards the occupants seated in. The ultrasonic sensor 13 measures the distance L to the target object by multiplying the time interval until the transmitted ultrasonic wave is received by the traveling speed of the ultrasonic wave and halving the multiplication result.
The distance L thus measured is supplied to the seating position detection circuit 14 and is corrected by the distance Lo between the ultrasonic sensor 13 and the storage position of the airbag 12 in the steering wheel, and the occupant seated on the seat from the airbag storage position. The distance L-Lo to the upper half of the body is sent to the timing control circuit 15 as data indicating the sitting position. In the example,
The ultrasonic sensor 13 and the seating position detection circuit 14 form a seating position sensor.

The timing control circuit 15 includes a signal gate 16 provided on a line connecting the collision determination circuit 6 and the airbag 12.
Outputs a gate signal to open and close the
When 6 is closed, the collision determination signal is sent to the airbag 12 as a deployment signal. This timing control circuit 15
In addition to the seating position detecting circuit 14, a moving distance estimating circuit 7 for estimating a moving distance of a driver who receives a shock at the time of a vehicle collision and moves forward while leaning is connected. Moving distance estimation circuit 7
Is the acceleration data supplied from the AD converter 5 by ΣΣG
Double integration is performed as shown in (k) to estimate the moving distance Lb of the occupant who moves forward due to the impact at the time of collision. On the other hand, as shown in FIG. 4B, the timing control circuit 15 obtains the rising inclination from the moving distance up to that moment at the moment when the collision determination is made, and the distance from this inclination to the predetermined buffer position. Lb, conversely, the time Tb required for the occupant to move to a position in front of the steering wheel by the distance La is calculated. However, the distance La is a distance from the steering wheel when the airbag 12 is deployed to a shape exhibiting the highest cushioning effect to the tip of the airbag 12, and is a value specific to the airbag 12 to be used. Also, Lb = (L-Lo) -La.

Before and after the collision determination, the AD converter 5
The acceleration data supplied from the vehicle acts as a negative acceleration, that is, a deceleration, on the occupant as in the case of braking. Also, the slope of the rising of the moving distance at the time of collision determination is
It is obtained by averaging the rate of change of the double integral value immediately before the collision determination within a fixed period. Therefore, the greater the impact associated with the collision, the greater the rising slope of the travel distance. This rising inclination corresponds to the forward rushing speed of the occupant at the time of collision determination, and it is assumed here that the occupant moves forward to the buffer position at a constant speed at the rushing speed. As shown, the buffer time tb
The time interval between (the intersection of the straight line indicating the rising slope of the moving distance obtained at the collision determination time point tc and the straight line indicating the buffer position) and the collision determination time point tc gives the time Tb. Therefore, the time Tb required for the occupant to move to a predetermined cushioning position due to the impact of the collision increases as the seating position moves away from the steering wheel, as shown by the alternate long and short dash line in FIG. Inversely proportional.

The timing control circuit 15, which has determined the time Tb required for the occupant to move to the predetermined buffer position, subsequently subtracts the time Ta required for the airbag 12 to deploy to the buffer position from the time Tb to collide. The time difference Tb-Ta between the determination signal and the expanded signal is obtained. However, when the time Ta is longer than the time Tb, the expansion signal is immediately generated immediately after the collision determination. As a result, for example, when the occupant is seated away from the steering wheel or when the impact at the time of a collision is weak, as shown in FIG. By being generated, the airbag 12 can be deployed in accordance with the movement of the occupant to the buffer position, and the occupant can be buffer-supported at the optimum position. On the contrary, when the occupant is seated near the steering wheel or when the impact at the time of a collision is strong, the airbag 12 is generated by generating a deployment signal without delay from the collision determination. It is possible to catch the occupant when the vehicle is deployed to the state where it has the most cushioning effect.

The ultrasonic transmitter 1 of the ultrasonic sensor 13 is also provided.
Since 3a is installed toward the seating position of the occupant, it is possible to accurately measure how far the upper half of the occupant's upper body is separated from the ideal cushioning position, and a seat slide position sensor or a seat belt wearing sensor is provided. Unlike the seating position sensor that indirectly detects the seating position from other than the occupant, the seating position can be accurately grasped regardless of the physique, the seating posture, and the like of the occupant. If there is a concern that ultrasonic waves may be absorbed by the occupant's clothes or the like, it may be dealt with by using a member made of a material that diffuses ultrasonic waves well in part of the seat belt.

Although the seating position sensor is constructed by using the ultrasonic sensor 13 in the above embodiment, other than this,
For example, a video camera with an autofocus function for capturing an image of a seated occupant and a calculation circuit for calculating the distance from the autofocus operation of the video camera to the subject can be used. In that case, the seating position of the occupant in the actual seated state can be accurately measured regardless of the sliding position of the seat and the inclination angle of the backrest. In addition to this, the seating position sensor can be configured by using a video camera that images a seated occupant and a calculation circuit that calculates the distance to the subject by pattern recognition of the image pickup output of the video camera. In that case, the same effect can be obtained. Further, as in the conventional case, for example, a seat slide position sensor that detects the slide position of the seat or a seat belt wearing sensor that detects the extension length of the seat belt is used to indirectly detect the seating position of the occupant. Good.

Further, in the above embodiment, the collision determination circuit 6 is configured to perform the collision determination by the offset integration and the impact force calculation. However, the collision determination circuit 6 only makes the collision determination when the offset integration value exceeds a certain limit. Alternatively, the collision may be determined when the deceleration exceeding a certain limit is detected. Further, the acceleration sensor 2 is not limited to a semiconductor acceleration sensor that detects a change in piezoresistance, but a piezoelectric element or a pure mechanical elastic spring may be used.

[0020]

As described above, according to the present invention, when the collision determination means determines that the vehicle has collided, the expansion signal generating means which receives the collision determination signal is accompanied by the sitting position of the occupant and the collision. The time required for the occupant to reach a predetermined cushioning position from deceleration is estimated, and when the time obtained by subtracting the time required for the airbag to deploy to the predetermined cushioning position from this estimated time has elapsed, Since the deployment signal is generated, the airbag can be deployed at the optimum timing according to the seating position of the occupant. For example, the occupant is seated away from the airbag, or the impact at the time of a collision is weak. In this case, the deployment signal is generated after a certain period of time from the collision determination, so that the airbag is deployed according to the movement of the occupant to the buffer position, and the occupant is buffered at the optimum position. On the contrary, if the occupant is seated near the airbag or if the impact at the time of a collision is strong, the deployment signal is generated without delay from the collision determination. It is possible to catch the occupant when the bag is deployed to the state where the cushioning effect is most effective, and the time from the collision determination to the deployment signal generation can be changed based on the sitting position and the deceleration at the time of the collision. Therefore, unlike the conventional method in which the deployment shape or the deployment speed of the airbag is simply changed according to the seating position of the occupant immediately before the collision, ideal cushioning considering the movement of the occupant during the collision is possible, etc. The excellent effect of.

Further, according to the present invention, the time required for the airbag to deploy to the predetermined buffer position is longer than the time for the occupant to reach the predetermined buffer position due to the deceleration caused by the collision. Is configured to generate a deployment signal almost at the same time as the collision determination, so if the time obtained by subtracting the time required for the airbag to deploy from the time it takes the occupant to reach the predetermined buffer position is negative, Considering the actual causal relationship that the deployment signal is always issued after the collision determination, and by taking a realistic response such that the deployment signal is generated almost at the same time as the collision determination, for example, the occupant can approach the airbag. When seated and when a strong impact is received during a collision, a deployment signal is generated without delaying the collision determination, and the airbag is deployed as far as possible to the state of cushioning effect. The effect of such can receive the passenger.

Further, according to the present invention, the expansion signal generating means double seats the seating position sensor for detecting the seating position of the occupant, the acceleration sensor for detecting the acceleration applied to the vehicle, and the output of the acceleration sensor. The occupant has a predetermined buffer position based on a moving distance estimating circuit that estimates a moving distance of the occupant forward by a double integral value until the collision determination time, and an output of the seating position sensor and an output of the moving distance estimating circuit. Time is calculated, the time required for the airbag to deploy to a predetermined buffer position is subtracted from the calculated time, and the gate signal is output when the time obtained by the subtraction elapses from the collision determination time point. By comprising a timing control circuit for outputting and a signal gate for receiving the output of the timing control circuit and outputting the collision determination signal as a development signal, By estimating how far the decelerated occupant will move forward with the seating position as the initial position based on the double integral value of the acceleration up to the collision determination time, the collision will occur after the actual collision. It is possible to estimate the moving distance of the occupant in proportion to the magnitude of the impact until the judgment is made.This allows not only the seating position of the occupant, but the forward movement of the occupant who receives the impact during a collision. It is possible to provide optimal cushioning in consideration of the above, and it is possible to firmly receive the occupant when the airbag is deployed to the state where the airbag has the highest cushioning effect, so the occupant protection function of the airbag device should be reliably improved. There is an effect such as being able to.

Further, according to the present invention, since the seating position sensor is constituted by using the ultrasonic sensor which measures the distance to the seated occupant with the round trip time of the ultrasonic wave, the transmitter of the ultrasonic sensor is used as the seating position of the occupant. The seat slide position sensor and the seat belt wear sensor can be accurately measured by installing it toward the seat, and how far the upper body, which is the cushioning target of the airbag at the time of a collision, is separated to the ideal cushioning position. Unlike a seating position sensor that indirectly detects the seating position in a medium other than the occupant such as the above, the seating position can be accurately grasped regardless of the occupant's physique and sitting posture, and ultrasonic waves from the occupant's clothes etc. The seating position can be detected with a low cost burden because a part of the seat belt that reflects ultrasonic waves can be used to solve the problem It can be an effect equal.

Furthermore, according to the present invention, the seating position sensor is provided by using a video camera with an autofocus function for capturing an image of a seated occupant, and an arithmetic circuit for calculating the distance from the autofocus operation of the video camera to the object. By configuring, the seating position of the occupant in the actual seated state can be accurately measured regardless of the slide position of the seat and the inclination angle of the backrest, and the seating position sensor images the seated occupant. Even when the video camera and the arithmetic circuit for recognizing the image pickup output of the video camera to calculate the distance to the subject are used, similar effects can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of an airbag device of the present invention.

FIG. 2 is a circuit configuration diagram of a collision determination circuit shown in FIG.

FIG. 3 is a diagram showing a collision determination map used in the arithmetic circuit shown in FIG.

FIG. 4 is a signal waveform diagram of each part of the circuit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Airbag device 2 Deployment signal generation means (acceleration sensor) 6 Collision determination means (collision determination circuit) 7 Deployment signal generation means (movement distance estimation circuit) 12 Airbag 13 Seating position sensor (ultrasonic sensor) 14 Seating position sensor ( Seating position detection circuit) 15 Expansion signal generating means (timing control circuit) 16 Expansion signal generating means (signal gate)

Claims (6)

[Claims] 1. A collision determination means for determining that a vehicle has collided, and a collision determination signal from the collision determination means,
Estimating the time from the occupant's seating position and the deceleration associated with the collision until the occupant reaches the predetermined buffer position, and subtracting the time required for the airbag to deploy to the predetermined buffer position from this estimated time. An airbag device, comprising: a deployment signal generating means for generating a deployment signal for the airbag when the time has elapsed. 2. The time required for the airbag to deploy to the predetermined buffer position rather than the time for the occupant to reach the predetermined buffer position due to the deceleration caused by the collision. 2. The airbag device according to claim 1, wherein the deployment signal is generated substantially at the same time when the collision is determined. 3. The expansion signal generating means double-integrates the seating position sensor for detecting the seating position of an occupant, the acceleration sensor for detecting the acceleration applied to the vehicle, and the output of the acceleration sensor, thereby performing the collision. The occupant reaches the predetermined buffer position from the movement distance estimating circuit that estimates the forward movement distance of the occupant with the double integral value up to the determination time point, and the output of the seating position sensor and the output of the movement distance estimating circuit. Time is calculated, the time required for the airbag to deploy to the predetermined buffer position is subtracted from the calculated time, and the gate signal is output when the time obtained by the subtraction has elapsed from the collision determination time point. A contract control characterized by comprising a timing control circuit for outputting and a signal gate for receiving the output of the timing control circuit and outputting the collision determination signal as a development signal. The airbag device according to claim 1. 4. The airbag apparatus according to claim 3, wherein the seating position sensor includes an ultrasonic sensor that measures a distance to a seated occupant with a round trip time of ultrasonic waves. 5. The seating position sensor includes a video camera with an autofocus function for capturing an image of a seated occupant, and an arithmetic circuit for calculating a distance from an autofocus operation of the video camera to a subject. Item 3. The airbag device according to item 3. 6. The seating position sensor includes a video camera for capturing an image of a seated occupant, and an arithmetic circuit for recognizing an image pickup output of the video camera to calculate a distance to a subject. 3. The airbag device described in 3.