Impact sensor for vehicle safety restraint system
First Claim
1. An acceleration sensor that comprises:
- a body of non-magnetic construction having a first internal cavity,a first permanent magnet mounted within said cavity for movement therewithin between at least first and second positions spaced from each other longitudinally in said cavity,means for resiliently urging said first magnet to said first position within said cavity,bistable magnetic flux-generating means carried by said body externally of said cavity adjacent to said second position, said flux generating means generating first and second stable states of magnetic flux, and being responsive to proximity of said first magnet for switching from said first state to said second state, andmeans positioned adjacent to said flux-generating means, and responsive to switching of said magnetic flux-generating means from said first state to said second state as a result of motion of said magnet from said first position to said second position to generate a sensor output signal,said magnet-urging means comprising a second permanent magnet mounted within said cavity at a position opposed to said first position of said first magnet, said first and second magnets having opposed like magnetic poles such that said first magnet is biased to said first position by magnetic repulsion from said second magnet, andmagnetically permeable means positioned externally of said cavity adjacent to said first position, said second magnet and said magnetically permeable means being constructed and arranged such that the sum of the forces on said first magnet due to repulsion from said second magnet and attraction to said magnetically permeable means remains substantially constant between said first and second positions.
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Accused Products
Abstract
An acceleration sensor that comprises a body of non-magnetic construction having a linear internal cavity of uniform cross section, and a pair of permanent magnetics movably mounted within such cavity with like magnetic poles opposed to each other, such that the magnetics are urged to opposite ends of the cavity by force of magnetic repulsion therebetween. At least one weigand wire is positioned externally of the cavity between the cavity ends, and has a longitudinal dimension parallel to the lineal dimension of the cavity. The weigand wire is characterized by two stable magnetic flux-generating states dependent upon application of an external magnetic field of appropriate polarity for switching between such states. An electrical coil is positioned adjacent to the weigand wire, and is responsive to switching between the two flux-generating states for generating a sensor output signal as a result of acceleration forces on either of the magnets sufficient to overcome the force of magnetic repulsion therebetween, and thus to bring one of the magnets into proximity with the wire. Additional magnets preset the weigand wire. Permeable material is used so that the magnetic force on the magnets does not change with a change in the position of the magnets.
58 Citations
33 Claims
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1. An acceleration sensor that comprises:
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a body of non-magnetic construction having a first internal cavity, a first permanent magnet mounted within said cavity for movement therewithin between at least first and second positions spaced from each other longitudinally in said cavity, means for resiliently urging said first magnet to said first position within said cavity, bistable magnetic flux-generating means carried by said body externally of said cavity adjacent to said second position, said flux generating means generating first and second stable states of magnetic flux, and being responsive to proximity of said first magnet for switching from said first state to said second state, and means positioned adjacent to said flux-generating means, and responsive to switching of said magnetic flux-generating means from said first state to said second state as a result of motion of said magnet from said first position to said second position to generate a sensor output signal, said magnet-urging means comprising a second permanent magnet mounted within said cavity at a position opposed to said first position of said first magnet, said first and second magnets having opposed like magnetic poles such that said first magnet is biased to said first position by magnetic repulsion from said second magnet, and magnetically permeable means positioned externally of said cavity adjacent to said first position, said second magnet and said magnetically permeable means being constructed and arranged such that the sum of the forces on said first magnet due to repulsion from said second magnet and attraction to said magnetically permeable means remains substantially constant between said first and second positions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An acceleration sensor that comprises:
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a body of non-magnetic construction having a first internal cavity, a first permanent magnet mounted within said cavity for movement therewithin between at least first and second positions spaced from each other longitudinally in said cavity, means for resiliently urging said magnet to said first position within said cavity, bistable magnetic flux-generating means carried by said body externally of said cavity adjacent to said second position, said flux generating means generating first and second stable states of magnetic flux, and being responsive to proximity of said magnet for switching from said first state to said second state, means positioned adjacent to said flux-generating means, and responsive to switching of said magnetic flux-generating means from said first state to said second state as a result of motion of said magnet from said first position to said second position to generate a sensor output signal, and means for setting said flux-generating means in said first state independently of said magnet so as to prepare said flux-generating means for proximity of said magnet to switch from said first state to said second state, said setting means comprising;
a second cavity in said body parallel to said first cavity, a second permanent magnet positioned within said second cavity for movement therewithin between at least a first position spaced from said flux-generating means and a second position adjacent to said flux generating means, and means for resiliently biasing said second magnet to its first position with a lesser force than that urging said first magnet to its first position, so that acceleration forces on said sensor urging said magnets toward said second position cause said second magnet to reach its second position adjacent to said flux-generating means, and thereby set said flux-generating means to said first state, prior to arrival of said first magnet at its second position. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An acceleration sensor that comprises:
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a body of non-magnetic construction having a first internal cavity, a first permanent magnet mounted within said cavity for movement therewithin between at least first and second positions spaced from each other longitudinally in said cavity, means for resiliently urging said first magnet to said first position within said cavity, bistable magnetic flux-generating means carried by said body externally of said cavity adjacent to said second position, said flux generating means generating first and second stable states of magnetic flux, and being responsive to proximity of said magnet for switching from said first state to said second state, and means positioned adjacent to said flux-generating means, and responsive to switching of said magnetic flux-generating means from said first state to said second state as a result of motion of said first magnet from said first position to said second position to generate a sensor output signal, said magnet-urging means comprising a second permanent magnet mounted within said cavity at a position opposed to said first position of said first magnet, said first and second magnets having opposed like magnetic poles such that said first magnet is biased to said first position by magnetic repulsion from said second magnet, said second permanent magnet being mounted within said cavity for movement between at least first and second positions, and said sensor further comprising bistable magnetic flux-generating means and output signal generating means positioned adjacent to said second position of said second magnet, such that a said sensor output signal is generated upon movement of either of said first and second permanent magnets to its associated second position, said bistable magnetic flux-generating means comprising a weigand wire positioned externally of said cavity adjacent to both of said second positions of said magnets, an electrical coil positioned adjacent to said wire, at least one additional cavity in said body parallel to said first cavity, third and fourth permanent magnets positioned in said at least one additional cavity, each of said third and fourth magnets being movable in said at least one additional cavity between an associated first position adjacent to the first position of said first and second magnets respectively and an associated second position adjacent to said wire, and means for resiliently urging said third and fourth magnets to said associated first positions with a lesser force than that urging said first and second magnets to their associated first positions. - View Dependent Claims (17)
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18. An acceleration sensor that comprises:
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a body of non-magnetic construction having a first internal linear cavity of uniform cross section, first and second permanent magnets mounted within said cavity, said magnets having like magnetic poles opposed to each other such that said magnets are urged to opposed ends of said cavity by force of magnetic repulsion between said magnets, at least one weigand wire positioned externally of said cavity between said ends, said wire being characterized by first and second magnetic flux-generating states dependent upon application of an external magnetic field, means positioned adjacent to said weigand wire and responsive to switching between said first and second flux-generating states for generating a sensor output signal as a result of acceleration forces on either of said magnets sufficient to overcome said magnetic repulsion and bring the magnet into proximity with said wire, said at least one weigand wire comprising first and second weigand wires oriented such that fluxes generated in said first sates are in respectively opposite directions, said signal generating means comprising first and second signal generating means respectively associated with said first and second wires, and means for selectively setting said first and second wires in respective first states, said first and second signal generating means comprising means responsive to switching from said first state to said second state to generate said sensor output signals, said setting means comprising at least one additional cavity in said body parallel to said first cavity, third and fourth permanent magnets positioned in said at least one additional cavity, each of said third and fourth permanent magnets being movable in said at least one additional cavity, means for resiliently urging said third and fourth permanent magnets to opposite ends of said at least one additional cavity to positions adjacent to said first and second magnets respectively with a lesser force than that urging said first and second magnets to said ends of said first cavity, said third and fourth permanent magnets each having a direction of magnetic polarization opposite to that of the adjacent first and second magnet. - View Dependent Claims (19, 20, 21, 22, 24)
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23. An acceleration sensor that comprises:
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a body of non-magnetic construction having a first internal linear cavity of uniform cross section, first and second permanent magnets mounted within said cavity, said magnets having like magnetic poles opposed to each other such that said magnets are urged to opposed ends of said cavity by force of magnetic repulsion between said magnets, at least one weigand wire positioned externally of said cavity between said ends, said wire being characterized by first and second magnetic flux-generating states dependent upon application of an external magnetic field, means positioned adjacent to said weigand wire and responsive to switching between said first and second states for generating a sensor output signal as a result of acceleration forces on either of said magnets sufficient to overcome said magnetic repulsion and bring the magnet into proximity with said wire, and first and second magnetically permeable means mounted on said body externally of said cavity adjacent to respective opposed ends of said cavity for resiliently attracting said magnets toward said respective ends of said cavity, said first and second magnets being identical, and said magnets and said magnetically permeable means being constructed and arranged such that the sum of the forces on either of said permanent magnets remains substantially constant independent of position within said cavity between at least the associated end of said cavity and a position adjacent to said wire. - View Dependent Claims (25, 26, 27, 28)
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29. An acceleration sensor that comprises:
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a body of non-magnetic construction having a closed linear internal cavity of uniform cross section, first and second permanent magnets movably mounted within said cavity, said magnets being identical and having like magnetic poles opposed to each other such that said magnets are urged to opposed ends of said cavity by force of magnetic repulsion between said magnets, first and second magnetically permeable means positioned on said body externally of said cavity adjacent to opposed ends of said cavity, said magnetically permeable means being constructed and arranged such that the sum of forces of magnetic attraction between said magnets and the adjacent magnetically permeable means, and magnetic repulsion between said magnets, remains substantially constant independent of the magnets'"'"' positions in said cavity, and means positioned between said cavity ends and responsive to magnetic flux for generating a sensor output signal upon motion of either of said magnets to a position adjacent to said generating means. - View Dependent Claims (30, 31, 32, 33)
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Specification