WO1999054172A1

WO1999054172A1 - A detection system for determining the proximity of an object relative to an airbag

Info

Publication number: WO1999054172A1
Application number: PCT/US1999/008421
Authority: WO
Inventors: Paul A. Witt
Original assignee: Siemens Automotive Corporation
Priority date: 1998-04-20
Filing date: 1999-04-16
Publication date: 1999-10-28

Abstract

In airbag deployment systems in motor vehicle it is necessary and desirable to know the position of an object such as an occupant (16) relative to the steering wheel or dashboard (14). Depending on which of two zones (20, 22) the occupant is located, the deployment systems may be modified as to the force of the deployment of the airbag.

Description

A DETECTION SYSTEM FOR DETERMINING THE PROXIMITY OF AN OBJECT RELATIVE TO AN AIRBAG

Field of Invention This invention relates to airbag safety restraint systems in general and more particularly to the sensing of objects in the passenger compartment of a motor vehicle just prior to the deployment of the airbags.

Background of the Invention

When a motor vehicle experiences a very sudden and rapid deceleration as a result of the vehicle hitting an object, the various safety restraint sensors in the vehicle function to determine the severity of the potential crash and to deploy various safety devices. Some of such devices control the movement of seat belts, shoulder belts, frontal airbags, side airbags, foot airbags, to name but a few.

Airbags are deployed by means of a high pressure gas being suddenly discharged in the airbag which then expands. The position of the airbags are such to secure the occupants of the vehicle from some of the dangers as a result of the crash. It has been found that the position of the occupant relative to the airbag is most important to the occupant's safety. Co-pending US patent application assigned to a common assignee was filed on October 21 , 1996 having US Serial Number 08/734,768 and entitled "An Occupant Sensing and Crash Behavior System" discloses a system that determines exactly where the occupant is by measuring several locations.

It is the purpose of the present system to determine if the occupant is within a predetermined area of the airbag inflation zone where the inflating airbag can strike the occupant with excessive force. Airbags by their very nature are termed as being aggressive and as such are known to cause injury to occupants who are "out-of-position". Unfortunately this is particularly true when the occupant is small such as a child under the age of twelve and not in a child seat or properly buckled-up. It is also true and well known that if the occupant, regardless of size is properly positioned in the occupant compartment, the aggressive airbag functions to protect and secure such occupant during time of inflation.

Since vehicle occupants are not always in their proper place for many different reasons, motor vehicle safety restraint systems must be designed to protect such out-of-position occupants. Unbelted occupants can be in a position relative to the inflating airbag that will cause the airbag to violently push them back into the seats.

Recent developments in airbag technology has brought variable and multistage inflation airbags into the motor vehicle. As a result, it is possible to adjust the rate of inflation to fit the circumstances of the occupant position.

Summary of Invention

In a motor vehicle equipped with an airbag safety restraint system, more particularly an airbag system having a variable or multistage inflation airbag inflator, a detection system determines the proximity of an object in the occupant compartment relative to the airbag deployment system. In particular, the object can be a human being. The system includes one or more airbags displaced about the vehicle cab in position to intercept the movement of the object in the occupant compartment. The safety restraint system has an acceleration sensing system coupled to the vehicle to determine the presence of a rapid vehicle deceleration such as caused by vehicle striking or being struck by another vehicle or object such as a tree or pole. The acceleration means operable to generate a deceleration electrical signal which is used to initiate the deployment of the airbags by initiating the operation of one or more inflators.

Positioned within the occupant compartment are one or more sensors that respond to the deceleration electrical signal to detect the presence or absence of an object in the compartment. Each one of the sensors responds to the presence of a object in a predetermined location field or zone relative to one of the airbags in the vehicle. Through various electrical circuitry that is responsive to each one of the sensors, a first electrical signal is generated. The generation of this first electrical signal indicates the presence or absence of the object when the object is within the location field of the sensor. The signal is communicated to the airbag deployment system which is responsive to at least the deceleration signals and the first signal for controlling the actuation of airbag deployment by controlling the rate of airbag inflation. If the object is in the first zone, which is typically within twenty centimeters from the dashboard of the vehicle, the deployment may be substantially reduced in aggressiveness in order to move the object away from the airbag and the dashboard. In a similar manner, if the object is in the next zone beyond the first zone, the deployment, is much more aggressive than in the first zone to move the object away from the airbag and the dashboard.

Detailed Description of the Drawings

In the drawings,

Fig. 1. is a schematic of the vehicle occupant relative to the dashboard of a motor vehicle;

Fig. 2. is system schematic of the detection system; and

Fig. 3. is a schematic of vehicle occupant illustrating the different locations of a frontal airbag. Detailed Description

Referring to the Figures by the characters of reference there is illustrated in Fig. 1. a schematic of the vehicle occupant compartment 10 of a motor vehicle. In particular there is shown the windshield 12, the dashboard 14 having a position for one or more sensors 15, an occupant 16 located in a front seat 18. Radiating from the sensors 15, are a first zone 20 and a second zone 22 which together indicate the zones wherein the aggressiveness of the airbag 24-26 is very severe.

The motor vehicle is equipped with an airbag safety restraint system to protect the occupants 16 in the event of vehicle experiencing a sudden deceleration bringing the vehicle to rest. The detection and deployment system 30 as described herein is used to determine the proximity of an occupant or object 16 in the occupant compartment 10 to the airbag deployment system. The object can be a human being in either the driver or passenger position, an inanimate object such as a box, a child seat, etc. to name but a few objects. It is contemplated that the detection system will be in use in all front seat positions. It is also contemplated that another such system will be useful to control the safety restraint system located behind the front seat for rear seat objects. The safety restraint system has one or more airbags 24-26 displaced or positioned in the dashboard 14 or other similar device. The airbags 24-26 are in position to function to intercept the movement, which is typically in a forward direction, of the object in the occupant compartment 10 when the vehicle is brought to a sudden stop. When the airbag 24-26 is in the driver's position it is typically in the steering wheel and when it is in the passenger position it is typically a large airbag that covers the center occupant position, if there is one, and the outboard occupant position. The detection system functions regardless of the airbag configuration. The acceleration sensing system, not shown, but is illustrated as one of the "other control systems" 32 is coupled to the vehicle and is typically in the frontal area of the vehicle. This system determines the presence of a rapid vehicle deceleration which typically brings the vehicle to rest and a large force is brought to bear against the vehicle. The acceleration sensing system typically has one or more sensors which are operable to generate an acceleration or deceleration electrical signal 34 when the system detects a rapid vehicle deceleration. Various configurations of the sensing systems may be used and such configurations do not affect the detection system. What the detection system needs is an electrical signal, a deceleration electrical signal 34 indicating that the airbag is to be inflated.

The detection system has one or more sensors 15 positioned within the occupant compartment 10. These sensors are responsive to the deceleration electrical signal 34 and operate to detect the presence or absence of an object in front of the airbags. Each one of the sensors 15 responds to the presence of a object in a predetermined location field relative to one of the airbags in the vehicle.

The sensors are responsive to the presence of the object within the danger zones relative to the facing surface of the airbag or dashboard. As previously mentioned, this surface can be the center of the steering wheel or the front of the dashboard. In any event, this surface faces the occupant in a direction that is relative to the normal direction of the vehicle, when the airbag is not deployed. This first danger zone 20 is between zero inches and eight (8) inches (20 cm) from the facing surface of the airbag in the direction of airbag deployment. Again this surface may be the steering wheel or the dashboard. It is the distance that an object gets to just before contact with the surface. This first danger zone 20 is the zone wherein the object or occupant can be within the striking distance of the break away door housing the airbag.

The second danger zone 22 is a zone that is beyond the first danger zone 20 and within a distance of fifteen (15) inches (40 cm) from the facing surface of the airbag in the direction of airbag deployment. The distances of each zone, the first danger zone 20 and the second danger zone 22 are matters of system configurations and the configurations of the vehicle and may be values other than those stated above. When the systems are used in the rear seat, the most rearward facing surface may well be the back of the front seats. The size of the two danger zones 20, 22 may vary due to vehicle configurations. These two zones 20, 22 can change relative to a difference between a front mounted airbag 36 and a top mounted airbag 38. This is illustrated in Fig. 3. The second zone 22 can be within the "power" inflation stage or the point wherein the airbag gas is first releasing from the inflator and the bag is unfolding.

The sensors 15 are connected to a sensor signal generator 39 which responds to the electrical signals that the sensors 15 generate. The function of the sensor signal generator 39 is to generate a control electrical signal 40 indicating the presence or absence of the object when the object is within the location field or zones 20, 22 of the sensor 15.

The sensor signal generator 39 functions to provide the necessary intelligence to the airbag deployment system 42 to control the inflation of the airbag or airbags 24-26. The airbag deployment system 42 is also responsive to the deceleration signal 34 to control the actuation of airbag deployment.

The sensors 15 of the detection system 30 may be one or more of the several different technologies for sensors. This system is not to determine the characteristic of the object, but to determine the position of the object. Infrared or camera sensors can be used to determine the distance from one object to the dashboard. In fact, by proper use and positioning such sensors may determine the relative size of an object. For instance it might determine that the hand of an occupant is on the airbag door which is not as dangerous to the occupant as it might be if their head was leaning within the aforementioned zones 20, 22. It is known that capacitive and passive infrared sensors have the ability to determine human presence by the detection of moisture and heat. But while all of this is nice to know, and in some systems such information is required, a metal object next to the airbag could be as dangerous as being too close to the dashboard surface as would be a person's head.

It is contemplated that for more sophisticated detection systems, a combination of sensor technologies might be used. But in each case, the proximity of the object is of paramount importance. The type of object may modify the rate of inflation . If the safety restraint system functions to deploy a control means, not shown, to operate to "pull-back" or tighten seat belts, the position of the object, in this case an occupant 16, is necessary to determine the amount and distance of the pull-back. If the safety restraint system is an inflatable seat belt system, again the position of the occupant 16 relative to the dashboard 14 is necessary to control the pull back force and the rate of application of the force.

While there has been shown and described essentially 2 sensors, each have a defined range, a sensor array may be positioned in the headliner of the vehicle to direct an essentially fan-shape sensing curtain covering the two zones 20, 22. The sensing curtain may be several ribs of sensing energy such as light waves to determine the position of the object relative to the dashboard. As an example, if the object is an occupant and if the occupant has, as previously indicated his arm against the dashboard, the array can determine this and through an algorithm in the detection control system, control the detonation of the squib to the airbag. There has thus been illustrated and shown a detection system to determine the proximity of an occupant in the occupant compartment of a motor vehicle to the airbag deployment system. The system has one or more airbags displaced in position to intercept the movement of the occupant in the occupant compartment when the vehicle has a sudden deceleration. One such airbag is located in the steering wheel and faces the driver's position and another one of the airbags faces the passenger's position.

An acceleration sensing system is coupled to the vehicle to determine the presence of a rapid vehicle deceleration such may occur when the vehicle is involved in a crash. The acceleration sensing system is operable to generate a deceleration signal at the appropriate time. One occupant sensor is positioned within the occupant compartment relative to each of the one or more airbags and is responsive to the deceleration electrical signal. The sensor detects the presence or absence of an occupant in a first predetermined location field or zone relative to each one of the airbags in the vehicle.

Another sensor is positioned within the occupant compartment relative to each of the airbags and responds to the deceleration electrical signal for detecting the distance from the airbag to the occupant in a second predetermined location field or zone relative to each one of the airbags in the vehicle.

A control system is responsive to each one of the sensors and generates a first electrical signal indicating the presence or absence of one or more occupants within the location fields of each of the sensors and also measures the distance the occupants are from the respective airbags. An airbag deployment system responds to at least the deceleration signal and this signal for controlling the actuation of airbag deployment. Such detection is information that is electrically supplied to the airbag deployment system, be it airbags, seat belts, inflatable seat belts, etc.

Claims

What is claimed is;

1. In a motor vehicle equipped with an airbag safety restraint system, a detection system to determine the proximity of an object in the occupant compartment relative to the airbag deployment system, comprises: one or more airbags displaced in position to intercept the forward movement of the object in the occupant compartment; acceleration sensing system coupled to the vehicle to determine the presence of a rapid vehicle deceleration, said acceleration means operable to generate a deceleration electrical signal when said system detects a rapid vehicle deceleration; one or more sensors positioned within the occupant compartment and responsive to said deceleration electrical signal for detecting the presence or absence of an object, each one of said sensors responds to the presence of a object in a predetermined location field relative to one of said airbags in the vehicle; means responsive to each of said sensors to generate a first electrical signal indicating the presence or absence of the object when the object is within said location field of said sensor; and airbag deployment system responsive to at least said deceleration signals and said first signal for controlling the actuation of airbag deployment.

2. In the detection system according to claim 1 wherein said object is a vehicle occupant.

3. In the detection system according to claim 1 wherein one of said sensors is responsive to the presence of the object within a first danger zone relative to the most rearward facing surface of the airbag, relative to the normal direction of the vehicle, when the airbag is not deployed.

4. In the detection system according to claim 3 wherein said first danger zone is within the first twenty centimeters from the most rearward facing surface of the airbag in the direction of airbag deployment.

5. In the detection system according to claim 4 wherein said first danger zone is within the first twenty centimeters from the surface of the vehicle dashboard.

6. In the detection system according to claim 1 wherein one of said sensors is responsive to the presence of an occupant within a second danger zone relative to the most rearward facing surface of the airbag, relative to the normal direction of the vehicle, when the airbag is not deployed.

7. In the detection system according to claim 6 wherein said second danger zone is a zone that is beyond the first danger zone and within forty centimeters from the most rearward facing surface of the airbag in the direction of airbag deployment.

8. In the detection system according to claim 1 wherein one of said sensors is an infrared sensor for determining the distance from said sensor to the object.

9. In the detection system according to claim 1 wherein one of said sensors is a capacitive sensor for determine if the object is an animate object.

10. In the detection system according to claim 1 wherein one of said sensors is a camera.

11 In the detection system according to claim 1 wherein said one or more sensors is positioned so as to form one or more fan-shaped arrays of the sensing energy between the dashboard and the object.

12. In a motor vehicle equipped with an airbag safety restraint system, a detection system to determine the proximity of an occupant in the occupant compartment relative to the airbag deployment system, comprising: one or more airbags displaced in position to intercept the forward movement of the occupant in the occupant compartment, one such airbag facing the driver's position and another of said airbag facing the passengers position; acceleration sensing system coupled to the vehicle to determine the presence of a rapid vehicle deceleration, said acceleration means operable to generate a deceleration electrical signal when said system detects a rapid vehicle deceleration; one sensor positioned within the occupant compartment relative to each of said airbags and responsive to said deceleration electrical signal for detecting the presence or absence of an occupant in a first predetermined location field relative to each one of said airbags in the vehicle; a second sensor positioned within the occupant compartment relative to each of said airbags and responsive to said deceleration electrical signal for detecting the distance from the airbag to an occupant in a second predetermined location field relative to each one of said airbags in the vehicle; means responsive to each of said sensors to generate a first electrical signal indicating the presence or absence of one or more occupants when the occupant is within said location field of each of said sensors and the distance the occupants are from the respective airbags; and airbag deployment system responsive to at least said deceleration signals and said first signal for controlling the actuation of airbag deployment.

13. In the detection system according to claim 12 wherein said first and second sensor is combined as one sensor.

14. In the detection system according to claim 12 wherein said first and second sensor are positioned in an array and each sensor emits a fan-shaped array of sensing energy in said first and second predetermined location fields.