Inductive transducers

Claim 2

An inductive displacement transducer comprising a hollow cylindrical coil; a magnetic core associated with said coil, said magnetic core being fOrmed as a plurality of U-shaped core pieces disposed each with one leg within the hollow of said coil and the other leg outside of the coil, the said U-shaped core pieces each comprising a single nonlaminated wafer having parallel flat faces and being disposed spaced apart from one another around the coil and having the free ends of their legs all at the same end of the coil; a plurality of nonmagnetic electrically insulating spacers fitted between the outermost legs of adjacent ones of said Ushaped core pieces around the outside of the coil, the thickness of said spacers in the radial direction with respect to the axis of said core being greater than the width of the outermost legs of said U-shaped core pieces in said radial direction whereby the spacers extend outwardly beyond the U-shaped core pieces in the radial direction; a cylindrical nonmagnetic housing into which said coil, said core and said spacers are fitted, the coil extending coaxially with the housing and the spacers contacting the inner cylindrical surface of the housing; and terminals in said housing coupled to said coil.

Claim 3

A transducer according to claim 1 wherein said cylindrical housing is closed at both ends and pressure-resisting support means extend between the housing end closures within the housing, said pressure resisting support means serving to prevent compression of the said U-shaped core pieces in the direction of the axis of the said coil as the result of pressure induced forces applied to one of the said housing end closures.

Claim 4

A transducer according to claim 2 wherein said pressure-resisting support means comprises a nonmagnetic support rod disposed to extend coaxially through the said coil, and a nonmagnetic star-piece disposed between the end face of the coil remote from the free ends of the legs of the said U-shaped core pieces and the adjacent end closure of the said housing, the said star-piece having at least three limbs which extend in different directions between the parts of said U-shaped core pieces which traverse said end face of the coil and serve to space said end face of the coil from the adjacent end closure of the housing, and the said support rod bearing against the said star-piece and against the other end closure of the housing, the said star-piece and support rod together being longer in the axial direction than the said U-shaped core pieces.

Claim 5

A compound inductive displacement transducer comprising a cylindrical housing; an active transducer unit within said housing; a compensatory transducer unit within said housing; said active and compensatory transducer units being substantially identical to each other and each comprising, in combination, a hollow cylindrical coil disposed coaxially with said housing, a magnetic core associated with said coil, said magnetic core being formed as a plurality of U-shaped core pieces disposed each with one leg within the hollow of said coil and the other leg outside of the coil, the said U-shaped core pieces each comprising a single nonlaminated wafer having parallel flat faces and being disposed spaced apart from one another around the coil with the free ends of their legs all at the same end of the coil, a plurality of nonmagnetic electrically insulating spacers fitted between the outermost legs of adjacent ones of said U-shaped core pieces around the outside of the coil, the thickness of said spacers in the radial direction with respect to the axis of said coil being greater than the width of the outermost legs of said U-shaped core pieces in said radial direction whereby the spacers extend outwardly beyond the U-shaped core pieces in the radial direction into contact with the inner cylindrical surface of the housing; and terminals in said housing coupled to the coils of the two transducer units.

Claim 6

A compound inductive displacement transducer comprising a cylindrical housing; an active transducer unit within said housing; a compensatory transducer unit within said housing; said active and compensatory transducer units being substantially identical to each other and each comprising, in combination, a hollow cylindrical coil disposed coaxially with said housing, a magnetic core associated with said coil, said magnetic core being formed as a plurality of U-shaped core pieces disposed each with one leg within the hollow of said coil and the other leg outside of the coil, the said U-shaped core pieces each comprising a single nonlaminated wafer having parallel flat faces and being disposed spaced apart from one another around the coil with the free ends of their legs all at the same end of the coil, a plurality of nonmagnetic electrically insulating spacers fitted between the outermost legs of adjacent ones of said U-shaped core pieces around the outside of the coil, the thickness of said spacers in the radial direction with respect to the axis of said coil being greater than the width of the outermost legs of said U-shaped core pieces in said radial direction whereby the spacers extend outwardly beyond the U-shaped core pieces in the radial direction into contact with the inner cylindrical surface of the housing; and terminals in said housing coupled to the coils of the two transducer units.

Claim 7

A compound transducer according to claim 4 wherein a reference plate formed of the same material as a target to be monitored by the transducer is disposed between the active and the compensatory Transducer units to provide compensation for variation of the magnetic permeability of the target with ambient temperature variation, and a ceramic spacer disposed between said reference plate and the compensatory transducer to simulate, for the compensatory transducer, a working gap substantially equal to the mean operational working gap at the active face of the active transducer unit.

Claim 8

A compound transducer as claimed in claim 4 further including a heat shield at one end of said housing in front of the active face of the active transducer unit, and a compensating shield formed of the same material and in the same dimensions as said heat shield disposed in front of the compensatory transducer unit to provide compensation for variation with temperature of the magnetic permeability of the heat shield.

Claim 9

A compound transducer as claimed in claim 4 wherein said terminals comprise close-wound spiral springs fitted to a ceramic terminal block secured within the housing.

Claim 10

A compound transducer as claimed in claim 4 wherein said housing has an integrally formed internal partition which divides the interior of the housing into front and rear sections, said active transducer unit being disposed in the section and said compensatory transducer unit being disposed in the rear section, and wherein pressure-resisting support means extend through the coil of the active transducer, from a closure member at the active face of the transducer to said partition.

Claim 11

A compound transducer as claimed in claim 8 wherein said pressure-resisting support means comprises a nonmagnetic support rod extending coaxially through the said coil, and a nonmagnetic star-piece disposed between the end face of the coil remote from the free ends of the legs of the said U-shaped core pieces and the adjacent end closure of the said housing, the said star-piece having at least three limbs which extend in different directions between the parts of said U-shaped core pieces which traverse said end face of the coil from the adjacent end closure of the housing, and the said support rod bearing against the said star-piece and against the other end closure of the housing, the said star-piece and support rod together being longer in the axial direction than the said U-shaped core pieces.

Claim 12

A compound transducer as claimed in claim 8 wherein the said compensatory transducer unit is disposed next to said partition in the rear section of the housing, wherein a substantially cylindrical terminal block carrying said terminals is disposed next to the said compensatory transducer unit in the rear section of the housing, and wherein a compression spring member is disposed next to said terminal block, said spring member being compressed between a closure member of the housing and said terminal block to maintain the compensatory transducer unit and the terminal block in position.

Claim 13

A compound inductive displacement transducer comprising a cylindrical housing; an active transducer unit fixed within said housing; a compensatory transducer unit fixed within said housing; said active and compensatory transducer units being substantially identical to one another and each comprising a hollow cylindrical coil disposed coaxially with said housing and a plurality of flat U-shaped core pieces spaced from one another around the coil and each having one leg within the hollow of the coil and the other leg outside of the coil with the free ends of their legs all at the same end of the coil; terminals in said housing coupled to the coils of the two transducer units; a heat shield at one end of said housing in front of the active face of the active transducer; and a compensating shield of the same material and dimensions as said heat shield disposed in front of the compensatory transducer unit to provide compensation for variation with temperature of the magnetic permeability of the heat shield.

Claim 14

A compound inductive displacement transducer comprising a cylindrical housing; an active transducer unit fixed within said housing; a compensatory transducer unit fixed within said housing; said active and compensatory transducer units being substantially identical to one another and each comprising a hollow cylindrical coil disposed coaxially with said housing and a plurality of flat U-shaped core pieces spaced from one another around the coil and each having one leg within the hollow of the coil and the other leg outside of the coil with the free ends of their legs all at the same end of the coil; terminals in said housing coupled to the coils of the two transducer units; a heat shield at one end of said housing in front of the active face of the active transducer; and a compensating shield of the same material and dimensions as said heat shield disposed in front of the compensatory transducer unit to provide compensation for variation with temperature of the magnetic permeability of the heat shield.

Claim 15

A compound inductive displacement transducer comprising a cylindrical housing having an integrally formed internal partitIon which divides the interior of the housing into front and rear sections, an active transducer unit fixed within the front section of said housing; a compensatory transducer unit fixed within the rear section of said housing; said active and said compensatory transducer units being substantially identical to one another and each comprising a hollow cylindrical coil disposed coaxially with said housing and a plurality of flat U-shaped core pieces spaced from one another around the coil and each having one leg within the hollow of the coil and the other leg outside of the coil with the free ends of their legs all at the same end of the coil; terminals in said housing coupled to the coils of the two transducer units; and pressure-resisting support means extending through the coil of the active transducer and extending between a closure member at the active face of the transducer and said partition.

Claim 16

A compound inductive displacement transducer comprising a cylindrical housing having an integrally formed internal partitIon which divides the interior of the housing into front and rear sections, an active transducer unit fixed within the front section of said housing; a compensatory transducer unit fixed within the rear section of said housing; said active and said compensatory transducer units being substantially identical to one another and each comprising a hollow cylindrical coil disposed coaxially with said housing and a plurality of flat U-shaped core pieces spaced from one another around the coil and each having one leg within the hollow of the coil and the other leg outside of the coil with the free ends of their legs all at the same end of the coil; terminals in said housing coupled to the coils of the two transducer units; and pressure-resisting support means extending through the coil of the active transducer and extending between a closure member at the active face of the transducer and said partition.

Claim 17

A compound transducer according to claim 12 wherein said pressure-resisting support means comprises a nonmagnetic support rod extending coaxially through the said coil, and a nonmagnetic star-piece disposed between the end face of the coil remote from the free ends of the legs of the said U-shaped core pieces and the adjacent end closure of the said housing, the said star-piece having at least three limbs which extend in different directions between the parts of said U-shaped core pieces which traverse said end face of the coil and serve to space said end face of the coil from the adjacent end closure of the housing, and the said support rod bearing against the said star-piece and against the other end closure of the housing, the said star-piece and support rod together being longer in the axial direction than the said U-shaped core pieces.

Claim 18

A compound transducer according to claim 12 wherein the said compensatory transducer unit is disposed next to said partition in the rear section of the housing, wherein a substantially cylindrical terminal block carrying said terminals is disposed next to the said compensatory transducer unit in the rear section of the housing, and wherein a compression spring member is disposed next to said terminal block, said spring member being compressed between a closure member of the housing and said terminal block to maintain the compensatory transducer unit and the terminal block in position.