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US5041784A
Expired / Lapsed
US
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Magnetic sensor with rectangular field distorting flux bar
Assignee: VISI-TRAK WORLDWIDE LLC
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Filing: 1989-11-16
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Granted: 1991-08-20
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Expires: 2009-11-16
Abstract
Abstract A magnetic sensor for use in measuring the position, velocity, and/or direction of movement of an object having alternating zones of magnetic conductivity with a permanent magnet member having a pole face facing the moving object and having an axis transverse to the direction of movement thereof. A ferromagnetic strip of high permeability is mounted on the face of the magnet coaxial therewith having a length dimension in the direction of movement of the object greater than the width dimension transverse to the direction of movement. The ferromagnetic strip distorts the field of the permanent magnetic member in the area of a pair of the sensor elements such that the flux lines in the area of each of the sensors are urged toward a transverse direction relative to the direction of movement of the object, whereby the flux field in the area of each of the sensor is uniform.
Inventors
- 👤 Elmer L. Griebeler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:17
CPC Classifications
F; F15; F15B; F15B15/00; F15B15/20; F15B15/28; F15B15/2815; F15B15/2861; F15B15/2846; G; G01; G01B; G01B7/00; G01B7/003; G01D; G01D5/00; G01D5/12; G01D5/14; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/488
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
228 words
In a cylinder and piston assembly of a metal die casting machine comprising a cylinder having a cylinder axis, a piston axially reciprocable within said cylinder by fluid pressure means in a direction of axial reciprocation, a piston rod of magnetic material connected to said piston for axial displacement therewith and extending from said cylinder, said piston rod having a peripheral surface including axially spaced grooves, said surface and grooves being covered by a nonmagnetic material proving a smooth wear surface for said piston rod, and transducer means positioned near said wear surface to produce electrical pulse signals in response to movement of said grooves past said transducer means, the improvement comprising: said transducer means including, substantially cylindrical permanent magnet means having a permanent magnet axis and an end transverse to said permanent magnet axis and facing said wear surface, rectangular flux plate means of ferromagnetic material on said end of said magnet means for distorting a magnetic field of said permanent magnet means on opposite sides of said permanent magnet axis in the direction of axial reciprocation, and first and second magnetic field sensor means on said plate means, said first sensor means being offset from said permanent magnet axis on one of said opposite sides thereof, and said second sensor means being offset from said permanent magnet axis on the other of said opposite sides thereof.
Claim 2
Dependent Claim
228 words
In a cylinder and piston assembly of a metal die casting machine comprising a cylinder having a cylinder axis, a piston axially reciprocable within said cylinder by fluid pressure means in a direction of axial reciprocation, a piston rod of magnetic material connected to said piston for axial displacement therewith and extending from said cylinder, said piston rod having a peripheral surface including axially spaced grooves, said surface and grooves being covered by a nonmagnetic material proving a smooth wear surface for said piston rod, and transducer means positioned near said wear surface to produce electrical pulse signals in response to movement of said grooves past said transducer means, the improvement comprising: said transducer means including, substantially cylindrical permanent magnet means having a permanent magnet axis and an end transverse to said permanent magnet axis and facing said wear surface, rectangular flux plate means of ferromagnetic material on said end of said magnet means for distorting a magnetic field of said permanent magnet means on opposite sides of said permanent magnet axis in the direction of axial reciprocation, and first and second magnetic field sensor means on said plate means, said first sensor means being offset from said permanent magnet axis on one of said opposite sides thereof, and said second sensor means being offset from said permanent magnet axis on the other of said opposite sides thereof.
Claim 3
Dependent Claim
72 words
The cylinder and piston assembly according to claim 1, wherein said permanent magnet means is circular in cross-section transverse to said permanent magnet axis defining a permanent magnet means diameter, and said flux plate means has a length in said direction of axial reciprocation substantially equal to the permanent magnet means diameter, a width transverse to said direction about one-quarter said diameter, and a height above said end about one-half said diameter.
Claim 4
Dependent Claim
23 words
The cylinder and piston assembly according to claim 2, wherein each said first and second sensor means includes silicon magnetoresistor sensing element means.
Claim 5
Dependent Claim
17 words
The cylinder and piston assembly according to claim 3, wherein said permanent magnet means is samarium-cobalt magnet.
Claim 6
Dependent Claim
71 words
The cylinder and piston assembly according to claim 4, wherein the distance between corresponding ends of adjacent grooves in said piston rod provides a pitch distance, each said first and second sensor means has a center in said direction, and said centers of said first and second sensor means are equally spaced from said axis and are spaced apart from one another a distance one and one-quarter of said pitch distance.
Claim 7
Dependent Claim
94 words
The cylinder and piston assembly according to claim 2 wherein said first sensor means comprises: a first positive leg circuit, a first negative leg circuit, a first neutral leg circuit, and first logic means not on said plate means, for generating a first signal responsive to movement of the piston, and wherein said second sensor means comprises: a second positive leg circuit, a second negative leg circuit, a second neutral leg circuit, and a second logic means not on said plate means, for generating a second signal responsive to the movement of the piston.
Claim 8
Dependent Claim
45 words
The cylinder and piston assembly according to claim 6 further comprising a digital process controller means, in electrical communication with the first and second sensor means, for determining a direction and a velocity of said piston responsive to the first signal and the second signal.
Claim 9
Dependent Claim
219 words
A transducer means in combination with a cylinder and piston assembly of a metal die casting machine comprising a cylinder having a cylinder axis, a piston axially reciprocable within said cylinder in a direction of axial reciprocation by fluid pressure means, a piston rod of magnetic material connected to said piston for axial displacement therewith and extending from said cylinder, said piston rod having a peripheral surface including alternating axially spaced portions of at least two different magnetic conductivity characteristics, the transducer means positioned near said surface to produce electrical pulse signals in response to movement of said portions past said transducer means, said transducer means further including substantially cylindrical permanent magnet means having a permanent magnet axis and an end transverse to said permanent magnet axis and facing said surface, rectangular flux plate means of ferromagnetic material on said end of said magnet means for distorting a magnetic field of said permanent magnet means on opposite sides of said permanent magnet axis in the direction of axial reciprocation, and first and second magnetic field sensor means on said plate means, said first sensor means being offset from said permanent magnet axis on one of said opposite sides thereof, and said second sensor means being offset from said permanent magnet axis on the other of said opposite sides thereof.
Claim 10
Dependent Claim
219 words
A transducer means in combination with a cylinder and piston assembly of a metal die casting machine comprising a cylinder having a cylinder axis, a piston axially reciprocable within said cylinder in a direction of axial reciprocation by fluid pressure means, a piston rod of magnetic material connected to said piston for axial displacement therewith and extending from said cylinder, said piston rod having a peripheral surface including alternating axially spaced portions of at least two different magnetic conductivity characteristics, the transducer means positioned near said surface to produce electrical pulse signals in response to movement of said portions past said transducer means, said transducer means further including substantially cylindrical permanent magnet means having a permanent magnet axis and an end transverse to said permanent magnet axis and facing said surface, rectangular flux plate means of ferromagnetic material on said end of said magnet means for distorting a magnetic field of said permanent magnet means on opposite sides of said permanent magnet axis in the direction of axial reciprocation, and first and second magnetic field sensor means on said plate means, said first sensor means being offset from said permanent magnet axis on one of said opposite sides thereof, and said second sensor means being offset from said permanent magnet axis on the other of said opposite sides thereof.
Claim 11
Dependent Claim
69 words
The combination according to claim 8, wherein said permanent magnet means is circular in cross-section transverse to said permanent magnet axis defining a permanent magnet means diameter, and said flux plate means has a length in said direction of axial reciprocation substantially equal to the permanent magnet means diameter, a width transverse to said direction about one-quarter said diameter, and a height above said end about one-half said diameter.
Claim 12
Dependent Claim
20 words
The combination according to claim 9, wherein each said first and second sensor means includes silicon magnetoresistor sensing element means.
Claim 13
Dependent Claim
15 words
The combination according to claim 10, wherein said permanent magnet means is a samarium-cobalt magnet.
Claim 14
Dependent Claim
68 words
The combination according to claim 11, wherein the distance between corresponding ends of adjacent portions in said piston rod provides a pitch distance, each said first and second sensor means has a center in said direction, and said centers of said first and second sensor means are equally spaced from said axis and are spaced apart from one another a distance one and one-quarter of said pitch distance.
Claim 15
Dependent Claim
91 words
The combination according to claim 9 wherein said first sensor means comprises: a first positive leg circuit, a first negative leg circuit, a first neutral leg circuit, and first logic means not on said plate means, for generating a first signal responsive to movement of the piston, and wherein said second sensor means comprises: a second positive leg circuit, a second negative leg circuit, a second neutral leg circuit, and a second logic means not on said plate means, for generating a second signal responsive to the movement of the piston.
Claim 16
Dependent Claim
42 words
The combination according to claim 13 further comprising a digital process controller means, in electrical communication with the first and second sensor means, for determining a direction and a velocity of said piston responsive to the first signal and the second signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-08-19 | 1995-02-18 | 1995-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-08-19 | 1999-02-18 | 1999-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-08-19 | 2003-02-18 | 2003-08-20 | $7700.00 | Window Closed / Lapsed |