Sensor of angle of a shaft with a base separating the shaft from a magnetoresistive sensing element
First Claim
1. An angle sensor for sensing the angle of a rotatable shaft, comprising:
- a base and a circuit supported by the base on a first side thereof, said base having a cavity for receipt of an end of said rotatable shaft, said cavity being located on a second side of said base opposite said circuit, said circuit including a magnetoresistive (MR) sensor;
a housing, said shaft being rotatable about a shaft axis, the housing holding the shaft with said end thereof disposed rotatably within said cavity upon connection of said housing to said base; and
a magnet connected to said end of said shaft, said magnet being located within said cavity and directing a magnetic field to said sensing element upon placement of said end of said shaft in said cavity, wherein the circuit outputs a signal indicating a rotational orientation of the magnet relative to said base.
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Accused Products
Abstract
A sensor for measurement of shaft angle values of a rotatable magnetized shaft employs a plurality of bridge circuits with corresponding magnetoresistive sensing elements disposed spaced-apart from a magnet disposed in an end of the shaft. The bridge circuits are held by a base which includes a cavity for receipt of the end of the shaft having the magnet. A housing secures the shaft and positions the shaft for rotation within the cavity. The base is formed of polybutalene teraphthallate which is permeable to magnetic lines of force, thereby permitting a coupling of the magnetic field of the shaft to the magnetoresistive sensors for measurement of an angle of the shaft about the shaft axis.
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Citations
10 Claims
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1. An angle sensor for sensing the angle of a rotatable shaft, comprising:
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a base and a circuit supported by the base on a first side thereof, said base having a cavity for receipt of an end of said rotatable shaft, said cavity being located on a second side of said base opposite said circuit, said circuit including a magnetoresistive (MR) sensor;
a housing, said shaft being rotatable about a shaft axis, the housing holding the shaft with said end thereof disposed rotatably within said cavity upon connection of said housing to said base; and
a magnet connected to said end of said shaft, said magnet being located within said cavity and directing a magnetic field to said sensing element upon placement of said end of said shaft in said cavity, wherein the circuit outputs a signal indicating a rotational orientation of the magnet relative to said base. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of fabricating an angle sensor for sensing the angle of a shaft, the shaft angle sensor comprising:
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a base and a circuit supported by the base on a first side thereof, said base being fabricated of a material transparent to a magnetic field, said base having a cavity for receipt of an end of said rotatable shaft, said cavity being located on a second side of said base opposite said circuit, said circuit including a magnetoresistive sensing element;
a housing, said shaft being rotatable about a shaft axis, the housing holding the shaft with said end thereof disposed rotatably within said cavity upon connection of said housing to said base; and
a magnet connected to said end of said shaft, said magnet directing a magnetic field to said sensing element upon emplacement of said end of said shaft in said cavity, wherein the circuit outputs a signal indicating a rotational orientation of the magnet relative to said base;
wherein the method comprises the steps of constructing said base of material transparent to the magnetic field with the base having said first side for holding said circuit and with said cavity located on said second side opposite said first side, constructing said housing with a cover, fabricating said cover of polybutalene teraphthallate, fabricating said base of polybutalene teraphthallate, fabricating said shaft of a composition of Teflon (a fluorinated hydrocarbon) impregnated with nylon and glass fiber, ultrasonically welding said cover to said base, said composition of said shaft inhibiting a welding of said shaft to said base and to said cover, thereby permitting rotation of said shaft relative to said base and to said cover, and placing said end of said shaft with the magnet in said cavity so that the magnetically transparent material of the base is located between the magnet and the magnetoresistive sensing element of said circuit.
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9. A shaft angle sensor, comprising:
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a rotatable shaft and a base of magnetically transparent material, said base being configured for receipt of said rotatable shaft;
a circuit having a magnetoresistive (MR) sensor, said circuit being located on a first side of said base opposite an end of said shaft which is located on a second side of said base;
a housing positioning said shaft relative to said base;
a magnet located at an end of said shaft and directing a magnetic field of the magnet to said MR sensor, said MR sensor being operative to output a signal to said circuit for indicating an orientation of said magnetic field, said circuit being responsive to the signal outputted by said MR sensor to provide an orientation of said shaft, there being a cavity located on the second side of said base for receiving said shaft and said magnet and for locating said magnet with respect to said MR sensor. - View Dependent Claims (10)
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Specification