Position detecting device for a linear drive including two magnets having like poles disposed facing each other for concentrating the flux at one point
AssigneeFesto AG & Co.
InventorsKurt Stoll, Johannes Volzer, Christoph Hanisch
Life of this patent
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Abstract
An ultrasonic position detecting device on a linear drive. The drive element of the linear drive bears a magnet arrangement cooperating with an adjacently placed sensor device which comprises an acoustic wave guide of magnetostrictive material. The magnet arrangement possesses an axially magnetized, annular or disk-like magnet part and, adjacent to the same, a pole part. By selection of the design of the pole part it is possible to affect the course of the magnetic field of the magnet part in order to achieve an optimum state for the sensor device.
Claims20
An ultrasonic position detecting device on a linear drive for the detection of the axial position of a movably arranged drive element positioned in the housing of the linear drive, said drive element movable along a longitudinal axis extending through the housing, comprising:
- a sensor device arranged fixedly in relation to the housing and radially spaced from the drive element, said sensor device having an acoustic waveguide extending in the longitudinal direction of the housing and made of a material suitable for magnetostriction and adapted to communicate with an evaluating device, and
- a magnet arrangement having a permanent magnet and connected with the drive element such that its magnetic field may pervade the radially adjacent acoustic waveguide, and wherein the permanent magnet of the magnet arrangement is designed in the form of an axially magnetized annular magnet part which is connected with the drive element such that its two pole surfaces are directed perpendicular to said longitudinal axis, and wherein the magnet arrangement further comprises an annular pole part arranged adjacent to one of the pole surfaces of the magnet part whereby the magnetic field passing therethrough is deflected towards said acoustic waveguide at a steep field strength gradient to facilitate the accurate detection of the axial position of the drive element.
An ultrasonic position detecting device in combination with a linear drive, comprising:
- a housing having an elongated space extending along a longitudinal axis therein;
- a drive element disposed in said space and movable along said longitudinal axis in response to application of a fluid driving force thereto;
- a sensor device arranged fixedly in relation to the housing and radially spaced from the drive element, said sensor device having an acoustic waveguide extending in the longitudinal direction of the housing and made of a material suitable for magnetostriction and adapted to communicate with an evaluating device;
- and
- a magnet arrangement having a permanent magnet and connected with the drive element such that its magnetic field may pervade the radially adjacent acoustic waveguide, and wherein the permanent magnet of the magnet arrangement is designed in the form of an axially magnetized annular magnet part which is connected with the drive element such that its two pole surfaces are directed perpendicular to said longitudinal axis, and wherein the magnet arrangement further comprises an annular pole part arranged adjacent to one of the pole surfaces of the magnet part whereby the magnetic field passing therethrough is deflected towards said acoustic waveguide at a steep field strength gradient to facilitate the accurate detection of the axial position of the drive element.
Dependencies are inferred from the claim text.