US5491422A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linear position sensor using a coaxial resonant cavity
Assignee: Mid-America Commercialization Corp
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Filing: 1995-03-14
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Granted: 1996-02-13
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Expires: 2015-03-14
Abstract
Abstract An apparatus (102) is for detecting the linear extension (position), velocity and acceleration of a hydraulic cylinder (108). The hydraulic cylinder (108) defines a variable length coaxial resonant cavity (112). Under the control of a controller (228), an RF transmitting section (114) and an RF receiving section (116) are used to determine the resonant frequency of the cavity. The resonant frequency of the cavity (112) is determined by comparing a received signal with a threshold and detecting slope intercept conditions.
Inventors
- 👤 Ali A. Bitar
- 👤 Charles W. Bowman
- 👤 Denny E. Morgan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:49
CPC Classifications
F; F15; F15B; F15B15/00; F15B15/20; F15B15/28; F15B15/2815; F15B15/2869; G; G01; G01D; G01D5/00; G01D5/48
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
178 words
A method for detecting a linear position of a piston (104) and a piston rod (106) being movable within a housing (110) of a hydraulic cylinder (108), including the steps of: producing an electromagnetic signal having a frequency varying between minimum and maximum values; delivering said electromagnetic signal into said hydraulic cylinder (108); receiving electromagnetic wave signals from said hydraulic cylinder (108); detecting a first positive slope intercept condition; tracking the frequency of said first positive slope intercept condition and responsively producing a first frequency signal; detecting a first negative slope intercept condition; tracking the frequency of said first negative slope intercept condition and responsively producing a second frequency signal; detecting a second positive slope intercept condition; tracking the frequency of said second positive slope intercept condition and responsively producing a third frequency signal; detecting a second negative signal slope intercept condition; tracking the frequency of said second negative slope intercept condition and responsively producing a fourth frequency signal; receiving said frequency signals and responsively determining the position, velocity and acceleration of said piston and piston rod (104,106).
Claim 2
Independent Claim
178 words
A method for detecting a linear position of a piston (104) and a piston rod (106) being movable within a housing (110) of a hydraulic cylinder (108), including the steps of: producing an electromagnetic signal having a frequency varying between minimum and maximum values; delivering said electromagnetic signal into said hydraulic cylinder (108); receiving electromagnetic wave signals from said hydraulic cylinder (108); detecting a first positive slope intercept condition; tracking the frequency of said first positive slope intercept condition and responsively producing a first frequency signal; detecting a first negative slope intercept condition; tracking the frequency of said first negative slope intercept condition and responsively producing a second frequency signal; detecting a second positive slope intercept condition; tracking the frequency of said second positive slope intercept condition and responsively producing a third frequency signal; detecting a second negative signal slope intercept condition; tracking the frequency of said second negative slope intercept condition and responsively producing a fourth frequency signal; receiving said frequency signals and responsively determining the position, velocity and acceleration of said piston and piston rod (104,106).
Claim 3
Dependent Claim
41 words
A method, as set forth in claim 1, wherein said piston (104), piston rod (106) and housing (110) form a variable length coaxial cavity (112) and said electromagnetic wave signal is a transverse electromagnetic wave delivered into said coaxial cavity (112).
Claim 4
Independent Claim
165 words
An apparatus (102) for detecting a linear position, a linear velocity, and a linear acceleration of a piston (104) and a piston rod (106) being movable within a housing (110) of a hydraulic cylinder (108), comprising: means (14) for producing an electromagnetic signal and delivering said electromagnetic signal into hydraulic cylinder (108), said electromagnetic signal having a frequency varying between predetermined minimum and maximum values; means (116) for sensing an electromagnetic wave signal within said hydraulic cylinder (108), detecting first and second positive slope intercept conditions and first and second negative slope conditions of said electromagnetic wave signal and producing first and third and second and fourth frequency signals in response to the frequency of said electromagnetic signal corresponding to said first and second positive slope conditions and said first and second negative slope conditions, respectively; and means (118) for receiving said first, second, third, and fourth frequency signals and responsively determining the position, velocity, and acceleration of said piston (104) and piston rod (106).
Claim 5
Independent Claim
165 words
An apparatus (102) for detecting a linear position, a linear velocity, and a linear acceleration of a piston (104) and a piston rod (106) being movable within a housing (110) of a hydraulic cylinder (108), comprising: means (14) for producing an electromagnetic signal and delivering said electromagnetic signal into hydraulic cylinder (108), said electromagnetic signal having a frequency varying between predetermined minimum and maximum values; means (116) for sensing an electromagnetic wave signal within said hydraulic cylinder (108), detecting first and second positive slope intercept conditions and first and second negative slope conditions of said electromagnetic wave signal and producing first and third and second and fourth frequency signals in response to the frequency of said electromagnetic signal corresponding to said first and second positive slope conditions and said first and second negative slope conditions, respectively; and means (118) for receiving said first, second, third, and fourth frequency signals and responsively determining the position, velocity, and acceleration of said piston (104) and piston rod (106).
Claim 6
Dependent Claim
35 words
An apparatus (102), as set forth in claim 3, wherein said piston (104), piston rod (106), and housing (110) define a variable length coaxial cavity (108) and said electromagnetic signal is a transverse electromagnetic wave.
Claim 7
Dependent Claim
40 words
An apparatus (102), as set forth in claim 3, wherein said slope intercept conditions detecting means includes means for tracking the frequency at which said first and second positive slope conditions and said first and second negative slope conditions occur.
Claim 8
Dependent Claim
42 words
An apparatus (104), as set forth in claim 5, wherein said position, velocity, and acceleration determining means includes means for determining first, second, third, and fourth periods of a predetermined number of cycles of said first, second, third, and fourth frequency signals.
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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) | 1999-02-12 | 1999-08-14 | 2000-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-02-12 | 2003-08-14 | 2004-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-02-12 | 2007-08-14 | 2008-02-13 | $7700.00 | Window Closed / Lapsed |