Measuring and testing – Testing by impact or shock – Accelerated or decelerated specimen
Reexamination Certificate
2000-01-19
2001-09-04
Noori, Max (Department: 2855)
Measuring and testing
Testing by impact or shock
Accelerated or decelerated specimen
C073S488000, C200S06145M
Reexamination Certificate
active
06282942
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a crash sensor for mounting in motor vehicles for sensing a crash, the sensor generating a signal, which is used by the Electronic Control Unit for deploying a passenger restraint system such as an air bag.
BACKGROUND OF THE INVENTION
Crash sensors have become widely adopted by many of the world's automobile manufacturers to sense that a crash is in progress and initiate the inflation of an air bag or tension of seat belts. These sensors may be electromechanical and constructed from a ball and tube such as disclosed in U.S. Pat. Nos. 5,031,931 and 5,237,134 to Thuen; and U.S. Pat. No. 152,392 to Husby. The ball-in-tube sensor currently in widespread use has a magnetic bias.
In the conventional ball-in-tube sensor, two cantilevered contacts are bridged by the ball and both the ball and the contacts may be gold plated to minimize the contact resistance. If the sensing mass instead of bridging the contacts, provides a varying magnetic field directly related to the sensing mass position to the Magnetic Field Sensor, the gold plating on the ball as well as the contacts themselves can be eliminated.
In U.S. Pat. No. 5,608,270, Meister discloses an impact sensor using a cylindrical permanent magnet axially slidable within a cavity and a magnetic sensing means adjacent the cavity. In the Meister sensor the vehicle impact forces cause the magnet to slide toward the opposite end and the magnetic sensing means provides an electrical impact signal that varies in magnitude as a function of the axial position of the magnet within the cavity. The Meister patent does not disclose a gas damped ball-in-tube sensor using a ferromagnetic sensing means.
OBJECTIVES AND SUMMARY OF THE INVENTION
An accelerometer or crash sensor according to the invention is adapted for installation on an automotive vehicle equipped with a passenger protective device such as an inflatable air bag or seat belt tensioner. When such vehicle is subjected to deceleration of the kind accompanying a crash, the air bag is inflated to provide a protective cushion for the occupant or the seat belt is pulled back against the QQsupant holding him in a safe position.
A sensor constructed according to the invention comprises a housing adapted to be mounted on the vehicle in a position to sense and respond to deceleration pulses. Within the housing is a body containing a tubular passage in which is mounted a movable deceleration sensing mass. The mass is movable in response to a deceleration pulse above a threshold value bias from an initial position along a path leading towards a Magnetic Field Sensor that is connected via suitable wiring to the operating mechanism of an inflatable air bag or seat belt tensioner.
A biasing spring or magnet acts on the deceleration sensing mass to bias the later to its initial position under a preselected force, which must be exceeded before the sensing mass, may move from its initial position. When the sensing mass is subjected to a deceleration creating an inertial force greater than the preselected biasing force it moves from its initial position toward its air bag or seat belt tensioner operating position. Movement of the sensing mass is fluid damped thereby requiring a finite period of time for the sensing mass to move from its initial position to its operating position.
It is another objective of this invention to utilize the magnetic field, which is present in a magnetically biased sensor to provide the means to monitor the position of the sensing mass in real time, thus enabling the airbag electronic control unit (ECU) to calculate sensing mass velocity and direction of motion. This information can be used to optimize deployment timing as well as deployment force (airbag pressure vs. time).
It is another objective of this invention to provide the means to calculate or predict the severity of a crash early in the event to further optimize deployment timing.
It is another objective of this invention to utilize a spring as a biasing force against the ball. This will eliminate the effect of temperature on the bias force. A smaller magnet must then be added to provide the desired variation of the magnetic field reaching the Magnetic Field Sensor.
Other objectives and advantages will become apparent from the description of the preferred embodiments below.
REFERENCES:
patent: 3974350 (1976-08-01), Breed
patent: 4284863 (1981-08-01), Breed
patent: 4329549 (1982-05-01), Breed
patent: 4900880 (1990-02-01), Breed
patent: 5031931 (1991-07-01), Thuen et al.
patent: 5153392 (1992-10-01), Husby et al.
patent: 5153393 (1992-10-01), Breed et al.
patent: 5237134 (1993-08-01), Thuen et al.
patent: 5430334 (1995-07-01), Meister
patent: 5608270 (1997-03-01), Meister
patent: 5856645 (1999-01-01), Norton
patent: 5895071 (1999-04-01), Norton
patent: 5984350 (1999-11-01), Hagan et al.
Breed Automotive Technology Inc.
Drayer Lonnie
Noori Max
Steinnon Patrick
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