Torque sensor

Claim 2

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; a cushioning sleeve disposed between said tubular magnetic yoke and said hollow cylindrical container for absorption of stress created therebetween; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque.

Claim 3

A torque sensor according to claim 1, wherein said tubular magnetic yoke is an amorphous magnetic alloy film rolled into a tubular form, a silicon steel plate rolled into a tubular form, or a ferrite tube, and said container is made of stainless alloy.

Claim 4

A torque sensor according to claim 1, further including a tubular cushioning sleeve made from a synthetic resin and disposed between said magnetic yoke and said container, said cushioning sleeve being softer than metal and having a thickness greater than 0.05 mm.

Claim 5

A torque sensor according to claim 3, wherein said cushioning sleeve is bonded to said magnetic yoke and said container.

Claim 6

A torque sensor according to claim 3, wherein said synthetic resin constituting said cushioning sleeve is Duracon, epoxy resin, bismaleimidetriazine resin, or Teflon.

Claim 7

A torque sensor according to claim 5, wherein said tubular magnetic yoke is an amorphous magnetic alloy film rolled into a tubular form, a silicon steel plate rolled into a tubular form, or a ferrite tube, and said container is made of stainless alloy.

Claim 8

A torque sensor according to claim 1, wherein said hollow cylindrical container is loose-fitted over said magnetic yoke to have a fit tolerance about 50 μm, and said container and said magnetic yoke are joined together by a screw fastener.

Claim 9

A torque sensor according to claim 1, wherein said hollow cylindrical container and said magnetic yoke are disposed with a clearance therebetween and firmly joined together by a tubular thin film of synthetic resin filled in said clearance between said container and said magnetic yoke.

Claim 10

A torque sensor according to claim 8, wherein said synthetic resin is softer than metal and has a thickness of about 50 μm.

Claim 11

A torque sensor according to claim 8, wherein said synthetic resin is an epoxy resin.

Claim 12

A torque sensor according to claim 1, wherein said coil means is composed of a tubular bobbin made from synthetic resin and disposed around said outer peripheral surface of said shaft with a space defined therebetween, and at least one coil wound around said bobbin, said tubular magnetic yoke being firmly fitted around said bobbin to hold said coil therebetween.

Claim 13

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, and the torque sensor being substantially uninfluenced by a difference in thermal expansion coefficients between said tubular magnetic yoke and said hollow cylinder or by a mechanical stress created in said tubular magnetic yoke.

Claim 14

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, and the torque sensor being substantially uninfluenced by a difference in thermal expansion coefficients between said tubular magnetic yoke and said hollow cylinder or by a mechanical stress created in said tubular magnetic yoke.

Claim 15

The torque sensor of claim 12, wherein said coil generates a magnetic field in a longitudinal direction of said shaft in response to current through said coil.

Claim 16

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; a cushioning member disposed between said tubular magnetic yoke and said hollow cylindrical container for absorption of stress created therebetween; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque.

Claim 17

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; a cushioning member disposed between said tubular magnetic yoke and said hollow cylindrical container for absorption of stress created therebetween; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque.

Claim 18

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said tubular magnetic yoke is an amorphous magnetic alloy film rolled into a tubular form, a silicon steel plate rolled into a tubular form, or a ferrite tube, and said container is made of stainless alloy.

Claim 19

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said tubular magnetic yoke is an amorphous magnetic alloy film rolled into a tubular form, a silicon steel plate rolled into a tubular form, or a ferrite tube, and said container is made of stainless alloy.

Claim 20

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; a tubular cushioning sleeve made from a synthetic resin and disposed between said magnetic yoke and said container, said cushioning sleeve being softer than metal and having a thickness greater than 0.05 mm; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque.

Claim 21

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; a tubular cushioning sleeve made from a synthetic resin and disposed between said magnetic yoke and said container, said cushioning sleeve being softer than metal and having a thickness greater than 0.05 mm; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque.

Claim 22

A torque sensor according to claim 16, wherein said cushioning sleeve is bonded to said magnetic yoke and said container.

Claim 23

A torque sensor according to claim 16, wherein said synthetic resin constituting said cushioning sleeve is Duracon, epoxy resin, bismaleimidetriazine resin, or Teflon.

Claim 24

A torque sensor according to claim 18, wherein said tubular magnetic yoke is an amorphous magnetic alloy film rolled into a tubular form, a silicon steel plate rolled into a tubular form, or a ferrite tube, and said container is made of stainless alloy.

Claim 25

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said hollow cylindrical container is loose-fitted over said magnetic yoke to have a fit tolerance about 50 μm, and said container and magnetic yoke are joined together by a screw fastener.

Claim 26

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said hollow cylindrical container is loose-fitted over said magnetic yoke to have a fit tolerance about 50 μm, and said container and magnetic yoke are joined together by a screw fastener.

Claim 27

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said hollow cylindrical container and said magnetic yoke are disposed with a clearance therebetween and firmly joined together by a tubular thin film of synthetic resin filled in said clearance between said container and said magnetic yoke.

Claim 28

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said hollow cylindrical container and said magnetic yoke are disposed with a clearance therebetween and firmly joined together by a tubular thin film of synthetic resin filled in said clearance between said container and said magnetic yoke.

Claim 29

A torque sensor according to claim 21, wherein said synthetic resin is softer than metal and has a thickness of about 50 μm.

Claim 30

A torque sensor according to claim 21, wherein said synthetic resin is an epoxy resin.

Claim 31

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said coil means is composed of a tubular bobbin made from synthetic resin and disposed around said outer peripheral surface of said shaft with a space defined therebetween, and at least one coil wound around said bobbin, said tubular magnetic yoke being firmly fitted around said bobbin to hold said coil therebetween.

Claim 32

A torque sensor comprising: a shaft for transmitting a torque exerted thereon, at least an outer peripheral surface of said shaft being made of a magnetic alloy having a magnetostrictive property; coil means disposed around said outer peripheral surface of said shaft for detecting a magnetic property of said magnetostrictive magnetic alloy; a tubular magnetic yoke disposed around said coil means for forming a magnetic circuit between itself and said magnetostrictive magnetic alloy; a hollow cylindrical container disposed around said magnetic yoke for containing the same, both end portions of said hollow cylindrical container being rotatably supported by bearings with gaps between the bearings and said tubular magnetic yoke; stepped portions formed on said shaft for supporting the bearings; and means operatively connected with said coil means for detecting a change in magnetic permeability of said magnetostrictive magnetic alloy in terms of a change in impedance of said coil means caused by the torque exerted on said shaft, thereby determining the torque, wherein said coil means is composed of a tubular bobbin made from synthetic resin and disposed around said outer peripheral surface of said shaft with a space defined therebetween, and at least one coil wound around said bobbin, said tubular magnetic yoke being firmly fitted around said bobbin to hold said coil therebetween.