Crush sensing vehicle crash sensor

Details Crush sensing vehicle crash sensor Crush sensing vehicle crash sensor

2000-12-26

2001-12-11

Dickson, Paul N. (Department: 3618)

Motor vehicles

With means for promoting safety of vehicle, its occupant or...

Responsive to engagement of portion of perimeter of vehicle...

C280S735000

Reexamination Certificate

active

06328126

ABSTRACT:

BACKGROUND OF THE INVENTION
In Society of Automotive Engineers (SAE) paper No. 930650 entitled “A Complete Frontal Crash Sensor System-I”, by Breed et al, which is incorporated herein by reference, the authors conclude that airbag crash sensors mounted in the crush zone are necessary for the proper sensing of airbag-required frontal crashes. They also conclude that such sensors should sense crashes to all portions of the front of the vehicle and that sensors which sense the crush of the vehicle are preferred. The theory of crush sensing is presented in the above-referenced U.S. patents and patent applications and in SAE paper No. 920122 entitled, “Performance of a Crush Sensor for Use with Automotive Airbag Systems”, by Breed et al, which is incorporated herein by reference.
The tape switch and rod-in-tube crush sensors described in the above-referenced U.S. patents and patent applications, have performed successfully on various staged vehicle frontal crashes into barriers and poles. These sensors are generally not sufficient for sensing side impacts as discussed in Breed, D. S., Sanders, W. T. and Castelli, V., “Sensing Side Impacts”, Society of Automotive Engineers (SAE) paper No. 940561, 1994, however, they can be successful when used in conjunction with a passenger compartment mounted electronic sensor or as a safing sensor. Similarly, they are also being considered when a deployable device, such as an airbag, is used for rear impacts.
Other technical papers which provide pertinent background information to this invention include:
1. Breed, D. S., Castelli, V. “Problems in Design and Engineering of Air Bag Systems”, Society of Automotive Engineers paper No. 880724, 1988.
2. Breed, D. S., Castelli, V. “Trends in Sensing Frontal Impacts”, Society of Automotive Engineers paper No. 890750, 1989.
3. Castelli, V., Breed, D. S. “Trends in Sensing Side Impacts”, Society of Automotive Engineers paper No. 890603, 1989.
4. Breed, D. S., Castelli, V. and Shokoohi, F. “Are Barrier Crashes Sufficient for Evaluating Air Bag Sensor Performance?”, Society of Automotive Engineers paper No. 900548, 1990.
5. Breed, D. S., Sanders, W. T. and Castelli, V. “A Critique of Single Point Crash Sensing”, Society of Automotive Engineers paper No. 920124. 1992.
6. Breed, D. S., Sanders, W. T. and Castelli, V. “Performance of a Crush Sensor for Use with Automobile airbag Systems”, Society of Automotive Engineers paper No. 920122, 1992.
7. Shokoohi, F., Sanders, W. T., Castelli, V., and Breed, D. S. “Cross Axis Specifications For Crash Sensors”. Automotive Technologies International Report, ATI 12004, 1991. Society of Automotive Engineers paper No. 930651, 1993.
8. Breed, D. S., Sanders, W. T. and Castelli, V. “A complete Frontal Crash Sensor System-I”, Society of Automotive Engineers paper No. 930650, 1993.
9. Breed, D. S. and Sanders, W. T. “Using Vehicle Deformation to Sense Crashes”, Presented at the International Body and Engineering Conference, Detroit Mich., 1993.
10. Breed, D. S., Sanders, W. T. and Castelli, V., “A complete Frontal Crash Sensor System-II”, Proceedings Enhanced Safety of Vehicles Conference, Munich, 1994, Published by the U.S. Department of Transportation, National Highway Traffic Safety Administration, Washington, D.C.
11. Breed, D. S., Sanders, W. T. and Castelli, V., “Sensing Side Impacts”, Society of Automotive Engineers paper No. 940561, 1994.
12. Breed, D. S., “Side Impact Airbag System Technology”, Presented at the International Body and Engineering Conference, Detroit Mich., 1994.
Other relevant prior art includes U.S. Pat. No. 3,859,482 to Matsui which will now be discussed in some detail. Matsui shows various devices which respond to the force (pressure using Matsui's terminology) which accompanies a vehicle frontal crash when material in the extreme front of the vehicle, or the impacting object itself, impacts the force detecting device. Matsui also mentions, but does not illustrate, the use of his force detectors on the rear and the side of the vehicle. The Matsui devices discriminate crashes based on the magnitude of this force on the detecting device, which as stated in the patent, are in the order of tons (metric). Many devices are described in Matsui however the following generalizations apply:
1. The Matsui sensors are mechanical pressure (force) detecting devices. This is stated in the title of the patent and throughout, there is only discussion of pressure being applied directly to the sensor. Except in those cases where a tape switch or a rope is used as the forwardmost point on the vehicle, there is always associated with the device a “Presser Member” whose function is to apply force directly to the sensor. Most importantly, this is a device which determines the severity of a crash based on force where the force is in the order of metric tons.
As discussed in greater detail below, the devices disclosed in the instant invention arc displacement sensors not force sensors, they do not require toils of force to actuated, are never placed at the forward most point on the vehicle, a “Presser Member” is not required or used, and they are designed to function by bending and not by compression.
2. The Matsui sensors are used in combination with a high level deceleration detector. In all cases, the Matsui sensor is used in conjunction with an acceleration sensor. This sensor is a low level discriminating sensor which is different from the safing sensor used on most current airbag systems. The difference between these types of sensors is that the Matsui sensor is not used alone to discriminate the crash, that is to determine whether the crash requires deployment of an airbag. An additional discriminating sensor is required. By contrast, in conventional airbag systems, a safing or arming sensor is used to guard against electrical shorts in the sensor perhaps caused by vehicle maintenance. The safing sensor will trigger on pothole impacts for example. It is not intended to provide information as to the severity of the crash. This is not the case in the Matsui acceleration sensor which is used in series with a force sensor. This is clear by the illustrated embodiment in
FIG. 29
which shows that the deceleration sensor requires a value of acceleration to trigger which is shown to be a substantial percent of the peak deceleration of curve A which is on the order of about 40 G's (see for example
FIG. 1
of reference
1
above). In contrast, typical safing or arming sensors trigger on a deceleration of less than about 2 G's.
Again, as will be discussed in detail below, in contrast, the sensors of the present invention do not require a high level deceleration sensor or any deceleration sensor for that matter. When the sensors of this invention are used as discriminating sensors, a low level safing or arming sensor can optionally be used to provide electrical isolation of the inflator initiator so that momentary electrical shorts do not cause deployment of the airbag. In other cases, they are used as safing sensors, for example in side impact sensing arrangements. There is no hint in Matsui of using his sensors as safing sensors.
3. In many illustrations of the Matsui devices a frangible system is used. In one case, for example, a wire inside a glass tube, or a glass rod or tube which has been plated with silver, is used. In some of these cases, a sensor design is illustrated which is substantially longer that it is thick or wide. In this mailer, the sensor can extend across a significant portion of the vehicle in much the same way that the rod-in-tube sensors of the instant invention are implemented. These frangible sensors trigger by being broken, usually by means of a “Presser Member” and to thereby break an electric circuit.
As discussed below, in contrast, the sensors of this invention are not frangible and trigger by bending not by breaking.
4. Due to the requirement that tons of force are needed to trigger the Matsui sensor, rigid mounting thereof is a requirement. This is particularly important at the place on the sensor where triggering is inten

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