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US 7,679,361 B2Granted
Position sensor having tubular detection coil
AssigneePanasonic Electric Works Co., Ltd.
InventorsMasahisa Niwa, Yukiko Inooka
Life of this patent
Estimating the term…
Abstract
A compact position sensor with high operational reliability is provided. This sensor has a tubular detection coil, a magnetic core movable in the detection coil, a drive circuit for the detection coil, a signal processing circuit for converting a change in impedance of the detection coil into an electric signal, and a guide means for guiding a movement of the magnetic core in the detection coil. The guide means has a guide portion connected to the magnetic core and a support portion for slidably supporting the guide portion. The magnetic core can be smoothly displaced in the detection coil without contacting an inner surface of the detection coil by a sliding movement of the guide portion relative to the support portion.
Claims16
A position sensor comprising:
- a tubular detection coil;
- a magnetic core movable in said detection coil;
- a drive circuit configured to provide a constant alternating voltage or a constant alternating current to said detection coil;
- a signal processing circuit configured to convert a change in impedance of said detection coil caused by a displacement of said magnetic core in said detection coil into an electric signal;
- and
- a guide comprising a guide portion connected to said magnetic core and a support portion configured to slidably support said guide portion,
- wherein said guide is formed such that said magnetic core is displaced in said detection coil without contacting an inner surface of said detection coil by a sliding movement of said guide portion relative to said support portion,
- wherein said guide portion has at least one guide bar extending generally parallel to said magnetic core,
- wherein said support portion has an opening, in which said magnetic core is inserted, at an end of said detection coil, and at least one guide opening, in which said at least one guide bar is inserted, at the periphery of said opening, and
- wherein said at least one guide bar inserted in said at least one guide opening is movable in an axial direction of said detection coil at the outside of said detection coil.
7 more elements
A position sensor comprising:
- a tubular detection coil;
- a magnetic core movable in said detection coil;
- a drive circuit configured to provide a constant alternating voltage or a constant alternating current to said detection coil;
- a signal processing circuit configured to convert a change in impedance of said detection coil caused by a displacement of said magnetic core in said detection coil into an electric signal;
- and
- a guide comprising a guide portion connected to said magnetic core and a support portion configured to slidably support said guide portion,
- wherein said guide is formed such that said magnetic core is displaced in said detection coil without contacting an inner surface of said detection coil by a sliding movement of said guide portion relative to said support portion,
- a case, in which said detection coil is accommodated,
- wherein said case has an opening at its one end, in which said magnetic core can be inserted,
- wherein said guide portion has at least one guide bar extending generally parallel with said magnetic core, and
- wherein said support portion slidably supports said at least one guide bar in an axial direction of said detection coil at the outside of said detection coil in said case.
8 more elements
A position sensor comprising:
- a tubular detection coil;
- a magnetic core movable in said detection coil;
- a drive circuit configured to provide a constant alternating voltage or a constant alternating current to said detection coil;
- a signal processing circuit configured to convert a change in impedance of said detection coil caused by a displacement of said magnetic core in said detection coil into an electric signal;
- and
- a guide comprising a guide portion connected to said magnetic core and a support portion configured to slidably support said guide portion,
- wherein said guide is formed such that said magnetic core is displaced in said detection coil without contacting an inner surface of said detection coil by a sliding movement of said guide portion relative to said support portion,
- wherein said support portion comprises an opening, in which said magnetic core can be inserted, at an end of said detection coil, and at least one rod-like projection extending generally parallel to an axial direction of said detection coil, and
- wherein said guide portion has a guide opening, in which said rod-like projection can be inserted.
6 more elements
A position sensor comprising:
- a tubular detection coil;
- a magnetic core movable in said detection coil;
- a drive circuit configured to provide a constant alternating voltage or a constant alternating current to said detection coil;
- a signal processing circuit configured to convert a change in impedance of said detection coil caused by a displacement of said magnetic core in said detection coil into an electric signal;
- and
- a guide comprising a guide portion connected to said magnetic core and a support portion configured to slidably support said guide portion,
- wherein said guide is formed such that said magnetic core is displaced in said detection coil without contacting an inner surface of said detection coil by a sliding movement of said guide portion relative to said support portion,
- wherein said guide portion comprises a rod-like member connected to an end of said magnetic core, and an outer tubular member connected to said rod-like member, and
- wherein said magnetic core is accommodated in said outer tubular member,
- said support portion comprises an inner tubular member, in which said detection coil is disposed, and
- an inner surface of said outer tubular member slidably contacts an outer surface of said inner tubular member in an axial direction of said detection coil.
8 more elements
A position sensor comprising:
- a tubular detection coil;
- a magnetic core movable in said detection coil;
- a drive circuit configured to provide a constant alternating voltage or a constant alternating current to said detection coil;
- a signal processing circuit configured to convert a change in impedance of said detection coil caused by a displacement of said magnetic core in said detection coil into an electric signal;
- and
- a guide comprising a guide portion connected to said magnetic core and a support portion configured to slidably support said guide portion,
- wherein said guide is formed such that said magnetic core is displaced in said detection coil without contacting an inner surface of said detection coil by a sliding movement of said guide portion relative to said support portion,
- a tubular shield member disposed around said detection coil,
- said guide portion comprises a rod-like member connected to an end of said magnetic core, and a tubular member connected to said rod-like member,
- wherein said magnetic core is accommodated in said tubular member, and
- wherein an outer surface of said tubular member slidably contacts an inner surface of said tubular shield member as said support portion in an axial direction of said detection coil.
8 more elements
A position sensor comprising:
- a tubular detection coil;
- a magnetic core movable in said detection coil;
- a drive circuit configured to provide a constant alternating voltage or a constant alternating current to said detection coil;
- a signal processing circuit configured to convert a change in impedance of said detection coil caused by a displacement of said magnetic core in said detection coil into an electric signal;
- and
- a guide comprising a guide portion connected to said magnetic core and a support portion configured to slidably support said guide portion,
- wherein said guide is formed such that said magnetic core is displaced in said detection coil without contacting an inner surface of said detection coil by a sliding movement of said guide portion relative to said support portion,
- wherein said guide portion comprises a rod-like member connected to an end of said magnetic core, and a tubular member connected to said rod-like member,
- wherein said magnetic core is accommodated in said tubular member,
- said support portion comprises an inner tube, in which said detection coil is disposed, and an outer tube disposed around said inner tube through a clearance, and
- said tubular member is slidably supported in the clearance between said inner tube and said outer tube in an axial direction said detection coil.
8 more elements
Dependencies are inferred from the claim text.