EP0266606A2
Expired / Lapsed
EP
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Position determining apparatus
Assignee: Vickers Inc
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Filing: 1987-10-17
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Granted: —
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Expires: 2007-10-17
Abstract
Abstract Apparatus for determining the position of a movable member (22) in an electrohydraulic servo system (10) which includes a linear actuator (20) having a cylinder (18) and a piston (22) variably positioned therewithin, a servo valve (12) responsive to valve control signals for coupling the actuator (20) to a source (14, 16) of hydraulic fluid, and control electronics (26) responsive to piston position for generating the valve control signals. A coaxial transmission line (40) is formed within the linear actuator (20) to include a center conductor (38) coaxial with the actuator (20) and an outer conductor (34). A bead (42) of ferrite or other suitable magnetically permeable material is coupled (44) to the piston (22) and surrounds the center conductor (38) of the transmission line (40) for altering impedance characteristics of the transmission line (40) as a function of position of the piston (22) within the clinder (18). Position sensing electronics (46, 50) include an oscillator (46) coupled to the transmission line (40) for launching electromagnetic radiation, and a phase detector (50) responsive to radiation reflected from the transmission line (40) for determining position of the piston (22) within the cylinder (18).
Inventors
- 👤 Lael Brent Taplin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 10:25
CPC Classifications
F; F15; F15B; F15B15/00; F15B15/20; F15B15/28; G; G01; G01D; G01D5/00; G01D5/12; G01D5/243
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
139 words
Apparatus for determining the position of a movable member comprising means forming a coaxial transmission line (40, 60) including center (38, 62) and outer (34, 18) electrical conductors, means (46) for launching electromagnetic radiation along said line (40, 60), means (42, 66) movable along said center conductor (38, 62) within said outer conductor (34, 18) for altering impedance characteristics of said transmission line (40, 60), means (44) for coupling said movable means (42, 66) to a movable member (22) such that said movable means (42, 66) is positioned along said center conductor (38, 18) as a function of position of the movable member (22) relative to said transmission line (40, 60), and means (50) responsive to electromagnetic radiation reflected by said transmission line (40, 60) for determining position of movable member (22) relative to said transmission line (40, 60).
Claim 2
Dependent Claim
139 words
Apparatus for determining the position of a movable member comprising means forming a coaxial transmission line (40, 60) including center (38, 62) and outer (34, 18) electrical conductors, means (46) for launching electromagnetic radiation along said line (40, 60), means (42, 66) movable along said center conductor (38, 62) within said outer conductor (34, 18) for altering impedance characteristics of said transmission line (40, 60), means (44) for coupling said movable means (42, 66) to a movable member (22) such that said movable means (42, 66) is positioned along said center conductor (38, 18) as a function of position of the movable member (22) relative to said transmission line (40, 60), and means (50) responsive to electromagnetic radiation reflected by said transmission line (40, 60) for determining position of movable member (22) relative to said transmission line (40, 60).
Claim 3
Dependent Claim
69 words
The apparatus set forth in claim 1 wherein said means forming said coaxial transmission line (40, 60) comprises a hollow tube (34, 18) forming said outer conductor and means (38, 62) centrally suspended within said tube forming said center conductor, and wherein said movable member (22) comprises means of magnetically permeable material (42, 66) movably carried with respect to said suspended means (38, 62) within said tube (34, 18).
Claim 4
Dependent Claim
47 words
The apparatus set forth in claim 2 wherein said tube (34, 18) and centrally suspended means (38, 62) have a characteristic impedance (Z₀) to electromagnetic radiation, and wherein said means forming said transmission line (40, 60) includes means terminating said transmission line in said characteristic impedance (Z₀).
Claim 5
Dependent Claim
43 words
The apparatus set forth in claim 3 wherein said magnetically-permeable means (42) is slidably carried by said center conductor (38), and wherein said coupling means comprises magnetic means (44) carried externally of said tube (34) and magnetically coupled to said magnetically-permeable means (42).
Claim 6
Dependent Claim
21 words
The apparatus set forth in claim 4 wherein said magnetic means comprises an annular magnet (44) externally surrounding said tube (34).
Claim 7
Dependent Claim
51 words
The apparatus set forth in claim 3 wherein said movable member (22) is positioned within said tube (18) and includes a central aperture (36), said center conductor (62) being slidably supported within said aperture (36) and said magnetically-permeable means (66) being carried by said movable member (22) surrounding said aperture (36).
Claim 8
Independent Claim
58 words
The apparatus set forth in any of claims 1 through 6 wherein said means for launching electromagnetic radiation comprises an rf generator (46) having an output coupled to said transmission line (40, 60), and wherein said means responsive to said reflected radiation comprises means (50) responsive to phase angle of said reflected radiation with respect to said output.
Claim 9
Dependent Claim
22 words
The apparatus set forth in claim 7 wherein said phase angle-responsive means comprises a phase detector (50) and an analog/digital converter (70).
Claim 10
Independent Claim
80 words
The apparatus set forth in any of claims 1 through 8 wherein said means forming a coaxial transmission line (40, 60) is arranged within a linear actuator (20) having a cylinder and piston and being connected through a servo valve (12) to a source (14, 16) of hydraulic fluid, wherein said movable member is the piston (22) of said actuator (20) and wherein said electromagnetic radiation responsive means (50) is connected to said servo valve (12) through servo electronics (26).
Claim 11
Dependent Claim
49 words
The appratus set forth in claim 9 wherein said piston (22) has a central aperture (36) coaxial with said cylinder (18), and wherein said means forming said coaxial transmission line (40, 60) comprises means (34, 38; 62) mounted coaxially within said cylinder (18) and projecting into said aperture (36).
References Cited (Backward Citations)
No citation records indexed.
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