Sensor including hall element, movable magnetic body and permane

Details Sensor including hall element, movable magnetic body and permane Sensor including hall element, movable magnetic body and permane

1992-06-19

1994-10-25

Strecker, Gerard R.

Electricity: measuring and testing

Magnetic

Displacement

73517R, 73DIG3, 200 6145R, G01P 1508, G01B 714, H01H 3502, B60R 2132

Patent

active

053592867

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a sensor.
More particularly, it relates to a sensor for automatically triggering safety devices in motor vehicles, with a housing and a body arranged in the housing and serving as a seismic mass so as to trigger a control signal when a predetermined threshold value is exceeded. Such a sensor in which a ball, serving as seismic mass, is arranged in the center of a socket with rising flanks is already known. The ball is deflected from this rest position either when a predetermined acceleration threshold is exceeded or when the motor vehicle is inclined at a predetermined angle. A reference light barrier is controlled by the rolling movement carried out by the ball and a measurement signal is accordingly generated. Further, it is known from DE-A1-35 40 947.9 to arrange an approximately cylindrical metal cylinder as seismic mass in the interior of a housing. A bore hole is constructed parallel to the axis in the seismic mass through which the light of a transmitter can reach a receiver in the basic position. If the seismic mass is tilted, the amount of light striking the receiver is reduced and a measurement signal is accordingly emitted. The center of gravity of the seismic mass is shifted with the aid of a recess constructed in the base of the seismic mass for influencing the triggering threshold. However, these sensors have the disadvantage that a relatively large tilting angle is necessary for obtaining an unequivocal measurement signal.


SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a sensor for automatically triggering safety devices in motor vehicles, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a sensor, which has a permanent magnet enclosed by a region of magnetically nonconducting material and is in a working connection with a Hall element, is arranged in the body composed magnetically conductive material, wherein the Hall element substantially evaluates the magnetic flux lines running parallel to the polarization direction of the permanent magnet, so that the Hall element evaluates the magnetic flux lines running parallel to the polarization direction of the permanent magnet in the basic position and evaluates the magnetic flux lines running in the opposite direction in the tilting position. has the advantage of a simple and robust construction. Its operation can be constantly checked in the rest state so that its susceptibility to trouble and likelihood of failure are relatively low. Unequivocal switching points are provided by the reversal of the magnetic field in the tilted state. High tolerances of the switching points of the Hall sensor are possible within a large range of application temperatures from -40.degree. to +125.degree. C. The sensor triggers reliably since the field reversal causes the signal of the Hall switch to change from a relatively high measurement signal to a relatively low measurement signal. A reliable triggering of the sensor is also possible during the rotation of the sensor, i.e. when an overturning of a motor vehicle is detected. The sensor works so as to be virtually free of wear. Its simple design makes it suitable for series manufacturing. The response threshold can easily be adapted to different types of application by varying the seismic mass. It can be produced so as to have a long service life, operating and manufacturing reliability and a small construction so that it is suitable for use in electronic circuits. No balancing or adjusting work need be carried out in the manufacturing of the sensor. are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the acco

REFERENCES:
patent: 3867844 (1975-02-01), Shimizu et al.
patent: 4191951 (1980-03-01), Fuzzell
patent: 4377088 (1983-03-01), Evert
patent: 4737774 (1988-04-01), Chapman et al.
patent: 4803426 (1989-02-01), Odagawa et al.
patent: 4870864 (1989-10-01), Io

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