Accelerometer with dual-magnet sensing mass
First Claim
1. An accelerometer comprisinga housing having a passage extending therein;
- a magnetically-permeable element secured to said housing proximate with the passage;
a magnetic sensing mass in the passage comprising a pair of permanent magnets and a magnetically-permeable spacer, the magnets being secured to opposite sides of the spacer so as to place a pair of like magnetic poles thereof in opposition, said sensing mass being magnetically biased towards said magnetically-permeable element so as to remain in a first position in the passage until said magnetic bias is overcome by acceleration of said housing, whereupon said sensing mass is displaced in response to such acceleration from said first position towards a second position in the passage, said magnetic bias being sufficient to return said sensing mass to said first position from any other position in the passage short of said second position; and
switch means operable by said sensing mass when said sensing mass is displaced to said second position.
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Accused Products
Abstract
An acceleration sensor comprises a tube formed of an electrically-conductive non-magnetic material; a magnetically-permeable element, such as a iron washer, proximate with the passage; and a sensing mass in the passage comprising a pair of permanent magnets and a spacer whose magnetic permeability increases with increasing temperature, with the magnets being secured to the opposite sides of the spacer so as to place a pair of like magnetic poles in opposition. In operation, the sensing mass interacts with the iron washer so as to be magnetically biased to a first position in the passage, while the magnetic-permeability of the spacer and, hence, the magnetic flux generated by the sensing mass adjusts to maintain a nearly constant threshold magnetic bias irrespective of variations in sensor temperature. The sensing mass is displaced in response to acceleration of the housing from its first position in the passage towards a second position therein when such acceleration overcomes the threshold magnetic bias, while the tube itself interacts with the sensing mass to provide magnetic damping therefor. Upon reaching the second position in the tube, the sensing mass electrically bridges a pair of contacts to indicate that a threshold level of acceleration has been achieved. An electrical coil is secured proximate with the iron washer which, when energized, reversibly magnetizes the latter, whereby the sensing mass is either repelled to the second position in the tube or more strongly biased towards the first position therein.
41 Citations
22 Claims
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1. An accelerometer comprising
a housing having a passage extending therein; -
a magnetically-permeable element secured to said housing proximate with the passage; a magnetic sensing mass in the passage comprising a pair of permanent magnets and a magnetically-permeable spacer, the magnets being secured to opposite sides of the spacer so as to place a pair of like magnetic poles thereof in opposition, said sensing mass being magnetically biased towards said magnetically-permeable element so as to remain in a first position in the passage until said magnetic bias is overcome by acceleration of said housing, whereupon said sensing mass is displaced in response to such acceleration from said first position towards a second position in the passage, said magnetic bias being sufficient to return said sensing mass to said first position from any other position in the passage short of said second position; and switch means operable by said sensing mass when said sensing mass is displaced to said second position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An accelerometer comprising
a tube; -
a magnetically-permeable element proximate with said tube; a magnetic sensing mass in said tube comprising a pair of permanent magnets and a magnetically-permeable spacer, the magnets being secured to opposite sides of the spacer so as to place a pair of like magnetic poles in opposition, said sensing mass being magnetically biased towards said magnetically-permeable element so as to remain in a first position in said tube until said magnetic bias is overcome by acceleration of said tube, whereupon said sensing mass is displaced in response to such acceleration from said first position towards a second position in said tube, said magnetic bias being sufficient to return said sensing mass to said first position from any other position in said tube short of said second position; and switch means operable by said sensing mass when said sensing mass is displaced to said second position. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification