US5656774A
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US
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Apparatus and method for sensing fluid level
Assignee: Technology Holding Co
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Filing: 1996-06-04
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Granted: 1997-08-12
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Expires: 2016-06-04
Abstract
Abstract A method and apparatus (10) for sensing a surface level (24) of fluid (12) in a tank (14) having an electrically conducting pickup tube (20) extending through a wall (16) of the tank (14) and into the fluid (12) includes a time domain reflectometry circuit (40) connected to the tube (20) for generating an incident pulse (68) that travels down the tube (20) and a portion of which is reflected at the surface (24) as a reflected pulse (70, 72) which travels back along the tube (20) and is sensed by the circuit (40). The circuit (40) utilizes the elapsed time between the generation of the incident pulse (68) and the receipt of the reflected pulse to determine the position of the surface (24) relative to a reference point. The robe (20) forms a transmission line with one of a plate (48), an outer tube (110) and a return tube (130).
Inventors
- 👤 Steven D. Nelson
- 👤 James R. Champion
- 👤 James S. Leonard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 05:54
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
285 words
An apparatus for sensing a level of a fluid (12) in a tank (14) comprising: a pulse means (40) for generating an incident pulse (68) and sensing a reflected pulse (70, 72) at an input/output (78) thereof and having a sensing signal output (102); and an electrically conductive pickup tube means (20) having a lower end (22) and being connected to said pulse means input/output (78) at a point adjacent an upper end (38) spaced a predetermined distance from said lower end (22), said pickup tube means (20) being adapted for insertion into a tank (14) with said lower end (22) in a first fluid (12) for drawing the first fluid (12) from the tank (14) through said pickup tube means (20) whereby when said pickup tube means (20) is inserted into the tank (14) with said lower end (22) in the first fluid (12) and said pulse means (40) generates said incident pulse (68), said incident pulse (68) travels from said point along said pickup tube means (20) to a surface (24) of the first fluid (12) at a boundary of a second fluid (26) above the first fluid (12) to generate said reflected pulse (70, 72) which travels back along said pickup tube means (20) to said point, and said pulse means (40) is responsive to said generation of said incident pulse (68) at said point and receipt of said reflected pulse (70, 72) at said point for determining an elapsed time between said generation and said receipt for generating a sensing signal at said sensing signal output (102), said sensing signal representing a distance between the surface (24) of the first fluid (12) and said point on said pickup tube means (20).
Claim 2
Independent Claim
285 words
An apparatus for sensing a level of a fluid (12) in a tank (14) comprising: a pulse means (40) for generating an incident pulse (68) and sensing a reflected pulse (70, 72) at an input/output (78) thereof and having a sensing signal output (102); and an electrically conductive pickup tube means (20) having a lower end (22) and being connected to said pulse means input/output (78) at a point adjacent an upper end (38) spaced a predetermined distance from said lower end (22), said pickup tube means (20) being adapted for insertion into a tank (14) with said lower end (22) in a first fluid (12) for drawing the first fluid (12) from the tank (14) through said pickup tube means (20) whereby when said pickup tube means (20) is inserted into the tank (14) with said lower end (22) in the first fluid (12) and said pulse means (40) generates said incident pulse (68), said incident pulse (68) travels from said point along said pickup tube means (20) to a surface (24) of the first fluid (12) at a boundary of a second fluid (26) above the first fluid (12) to generate said reflected pulse (70, 72) which travels back along said pickup tube means (20) to said point, and said pulse means (40) is responsive to said generation of said incident pulse (68) at said point and receipt of said reflected pulse (70, 72) at said point for determining an elapsed time between said generation and said receipt for generating a sensing signal at said sensing signal output (102), said sensing signal representing a distance between the surface (24) of the first fluid (12) and said point on said pickup tube means (20).
Claim 3
Dependent Claim
25 words
The apparatus according to claim 1 wherein said pulse means (40) repetitively generates said incident pulse (68) at a pulse rate of approximately two MHz.
Claim 4
Dependent Claim
62 words
The apparatus according to claim 1 wherein said pulse means (40) includes an oscillator means (74) for generating a plurality of pulses at an output and a pulse generator means (76) having an input connected to said oscillator means output for generating at said pulse means input/output (78) one of said incident pulses (68) in response to each of said oscillator pulses.
Claim 5
Dependent Claim
38 words
The apparatus according to claim 1 wherein said pulse means (40) includes a sample gate means (88) having an input connected to said pulse means input/output (78) and an output for selectively passing said reflected pulse (70, 72).
Claim 6
Dependent Claim
71 words
The apparatus according to claim 4 wherein said pulse means (40) includes an oscillator means (74, 80) having an output connected to a gate input of said sample gate means (88) for generating a plurality of sample pulses at a first frequency phase modulated at a second frequency lower than said first frequency to turn said sample gate means (88) on and off and selectively pass said reflected pulse (70, 72).
Claim 7
Dependent Claim
22 words
The apparatus according to claim 5 wherein said first frequency is approximately two MHz and said second frequency is approximately forty Hz.
Claim 8
Dependent Claim
233 words
The apparatus according to claim 1 wherein said pulse means (40) includes a first oscillator means (74) for generating a plurality of pulses at a first frequency at an output, a first pulse generator means (76) having an input connected to said first oscillator output for generating at said pulse means input/output (78) one of said incident pulses (68) in response to each of said oscillator pulses, a sample gate means (88) connected between said pulse means input/output (78) and said sensing signal output (102), a second oscillator means (80) for generating a plurality of pulses at a second frequency at an output, a ramp circuit means (82) having an input connected to said second oscillator output for generating a ramp signal at an output in response to each one of said second oscillator pulses, a mixing circuit means (84) having a first input connected to said first oscillator output and a second input connected to said ramp circuit output and being responsive to said first oscillator pulses and said ramp signal for generating a signal at an output, and a second pulse generator means (86) having an input connected to said mixing circuit output and an output connected to a gate input of said sample gate means (88) for generating gate pulses in response to said mixing circuit output signal to switch said sample gate means (88) between sample and hold conditions.
Claim 9
Dependent Claim
58 words
The apparatus according to claim 1 including a coaxial cable (42) having a central conductor (44) connected between said pulse means input/output (78) and said point on said pickup tube means (20) and said pulse means (40) compensates for a travel time of said incident pulse (68) and said reflected pulse (70, 72) along said central conductor (44).
Claim 10
Dependent Claim
54 words
The apparatus according to claim 1 including a reflector base plate and mounting plate (48, 116, 136) adapted to be attached to the tank (14) and having an aperture (50, 114, 134) formed therein through which said pickup tube means (20) extends in non-contacting relationship with said point adjacent said plate (48, 116, 136).
Claim 11
Dependent Claim
44 words
The apparatus according to claim 1 including a reserve end (30) attached to said lower end (22) of said pickup tube means (20) for drawing the first fluid (12) in the tank (14) below said lower end (22) into said pickup tube means (20).
Claim 12
Dependent Claim
18 words
The apparatus according to claim 10 wherein said reserve end (30) is formed of an electrically non-conducting material.
Claim 13
Dependent Claim
40 words
The apparatus according to claim 1 including a liquid level gauge means (58) connected to said sensing signal output (102) and responsive to said sensing signal for indicating the level (24) of the first fluid (12) in the tank (14).
Claim 14
Dependent Claim
40 words
The apparatus according to claim 1 including a low liquid warming means (104) connected to said sensing signal output (102) and responsive to said sensing signal for indicating a low level of the first fluid (12) in the tank (14).
Claim 15
Dependent Claim
38 words
The apparatus according to claim 1 including an outer tube means (110) surrounding said pickup tube means (20) for returning to the tank (14) at least a portion of the first fluid (12) drawn from the tank (14).
Claim 16
Dependent Claim
66 words
The apparatus according to claim 14 including a first lead (120) connected between said pulse means input/output (78) and said point on said pickup tube means (20) and a second lead (118) connected between said pulse means input/output (78) and said outer tube (110) whereby said pickup tube means (20) and said outer tube (110) function as a coaxial transmission line for said incident pulse (68).
Claim 17
Dependent Claim
44 words
The apparatus according to claim 1 including a return tube (130) adapted for insertion into the tank (14) adjacent said pickup tube means (20) for returning to the tank (14) at least a portion of the first fluid (12) drawn from the tank (14).
Claim 18
Dependent Claim
67 words
The apparatus according to claim 16 including a first lead (138) connected between said pulse means input/output (78) and said point on said pickup tube means (20) and a second lead (140) connected between said pulse means input/output (78) and said return tube (130) whereby said pickup tube means (20) and said return tube (130) function as a parallel pair transmission line for said incident pulse (68).
Claim 19
Dependent Claim
46 words
The apparatus according to claim 1 including a float (150) slidably mounted on said pickup tube means (20) for floating at the surface (24) of the first liquid in the tank (14) and for generating said reflected pulse (70, 72) with at least a predetermined magnitude.
Claim 20
Independent Claim
280 words
An apparatus for sensing a level of a fluid (12) in a tank (14) having an electrically conductive pickup tube (20) for drawing the fluid (12) from the tank (14) extending through a wall (16) of the tank (14) into the fluid (12) comprising: a pulse means (40) for generating an incident pulse (68) and sensing a reflected pulse (70, 72) at an input/output (78) thereof; a pulse transmission means (48, 110, 130); a first conductor (44, 118, 138) having one end connected to said pulse means input/output (78) and an opposite end adapted to be connected to an electrically conductive pickup tube (20); and a second conductor (46, 120, 140) having one connected to said pulse means input/output (78) and an opposite end connected to said pulse transmission means (48, 110, 130) whereby when said opposite end of said first conductor (44, 118, 138) is connected to a point spaced a predetermined distance from a lower end (22) of an electrically conductive pickup tube (20) and the lower end (22) of the pickup tube (20) extends through a wall (16) of a tank (14) into a fluid (12) in the tank (14), said pickup tube (20) and said pulse transmission means (48, 110, 130) function as a transmission line for said incident pulse (68) which travels from the point along the pickup tube (20) to a surface level (24) of the fluid (12) to generate said reflected pulse (70, 72), an elapsed time between generation of said incident pulse (68) and receipt of said reflected pulse (70, 72) being proportional to a distance between the point and the surface level (24) of the fluid (12) in the tank (14).
Claim 21
Independent Claim
280 words
An apparatus for sensing a level of a fluid (12) in a tank (14) having an electrically conductive pickup tube (20) for drawing the fluid (12) from the tank (14) extending through a wall (16) of the tank (14) into the fluid (12) comprising: a pulse means (40) for generating an incident pulse (68) and sensing a reflected pulse (70, 72) at an input/output (78) thereof; a pulse transmission means (48, 110, 130); a first conductor (44, 118, 138) having one end connected to said pulse means input/output (78) and an opposite end adapted to be connected to an electrically conductive pickup tube (20); and a second conductor (46, 120, 140) having one connected to said pulse means input/output (78) and an opposite end connected to said pulse transmission means (48, 110, 130) whereby when said opposite end of said first conductor (44, 118, 138) is connected to a point spaced a predetermined distance from a lower end (22) of an electrically conductive pickup tube (20) and the lower end (22) of the pickup tube (20) extends through a wall (16) of a tank (14) into a fluid (12) in the tank (14), said pickup tube (20) and said pulse transmission means (48, 110, 130) function as a transmission line for said incident pulse (68) which travels from the point along the pickup tube (20) to a surface level (24) of the fluid (12) to generate said reflected pulse (70, 72), an elapsed time between generation of said incident pulse (68) and receipt of said reflected pulse (70, 72) being proportional to a distance between the point and the surface level (24) of the fluid (12) in the tank (14).
Claim 22
Dependent Claim
64 words
The apparatus according to claim 19 wherein said pulse means (40) includes an oscillator means (74, 76) for generating a plurality of said incident pulses (68) and being connected to said input/output (78) and a gate means (74, 80, 82, 84, 86, 88) connected to said input/output (78) for selectively sampling for said reflected pulse (70, 72) associated with each said incident pulse (68).
Claim 23
Dependent Claim
50 words
The apparatus according to claim 20 wherein said oscillator means (74, 76) generates said incident pulses (68) at a first frequency and said gate means (74, 80, 82, 84, 86, 88) samples at a rate which is said first frequency modulated by a second frequency lower than said first frequency.
Claim 24
Dependent Claim
63 words
The apparatus according to claim 20 wherein said pulse means (40) includes a sensing signal means (90, 92, 94, 96, 98, 100, 102) for generating a sensing signal in response to said reflected pulses (70, 72) and being connected to said gate means (74, 80, 82, 84, 86, 88), said sensing signal representing an amount of the fluid (12) in the tank (14).
Claim 25
Independent Claim
157 words
A method of sensing a level (24) of a fluid (12) in a tank (14) comprising the steps of: a. inserting an electrically conducting pickup tube (20) into a tank (14) with a lower end (22) of the pickup tube (20) positioned at a lowest fluid level to be sensed; b. generating an incident pulse (68) at a predetermined point (78) and applying said incident pulse (68) to the pickup tube (20), said incident pulse (68) travelling toward the pickup tube lower end (22) and generating a reflected pulse (70, 72) at a surface level (24) of the fluid (12); c. sensing said reflected pulse (70, 72) at the point (78); d. determining an elapsed time between generation of said incident pulse (68) at the point (78) and receipt of said reflected pulse (70, 72) at the point (78); and e. indicating an amount of the fluid (12) in the tank (14) based upon said elapsed time.
Claim 26
Independent Claim
157 words
A method of sensing a level (24) of a fluid (12) in a tank (14) comprising the steps of: a. inserting an electrically conducting pickup tube (20) into a tank (14) with a lower end (22) of the pickup tube (20) positioned at a lowest fluid level to be sensed; b. generating an incident pulse (68) at a predetermined point (78) and applying said incident pulse (68) to the pickup tube (20), said incident pulse (68) travelling toward the pickup tube lower end (22) and generating a reflected pulse (70, 72) at a surface level (24) of the fluid (12); c. sensing said reflected pulse (70, 72) at the point (78); d. determining an elapsed time between generation of said incident pulse (68) at the point (78) and receipt of said reflected pulse (70, 72) at the point (78); and e. indicating an amount of the fluid (12) in the tank (14) based upon said elapsed time.
Claim 27
Dependent Claim
82 words
The method according to claim 23 wherein the step a. includes inserting the pickup tube (20) through an aperture (50) formed in a reflector base and mounting plate (48) in a non-contacting relationship and positioning the point at the plate (48) and the step b. includes providing a first connection (44) between the pickup tube (20) and a pulse means (40) for generating said incident pulse (68) and providing a second connection (46) between the pulse means (40) and the plate (48).
Claim 28
Dependent Claim
95 words
The method according to claim 23 wherein the step a. includes surrounding the pickup tube (20) with an outer tube (110) and inserting the pickup tube (20) and the outer tube (110) through an aperture (114) formed in a plate (116) in a non-contacting relationship and positioning the point at the plate (116) and the step b. includes providing a first connection (120) between the pickup tube (20) and a pulse means (40) for generating said incident pulse (68) and providing a second connection (118) between the pulse means (40) and the outer tube (110).
Claim 29
Dependent Claim
89 words
The method according to claim 23 wherein the step a. includes inserting the pickup tube (20) and a return tube (130) through associated ones of a pair of apertures (134) formed in a plate (136) in a non-contacting relationship and positioning the point at the plate (136) and the step b. includes providing a first connection (138) between the pickup tube (20) and a pulse means (40) for generating said incident pulse (68) and providing a second connection (140) between the pulse means (40) and the return tube (130).
Claim 30
Dependent Claim
52 words
The method according to claim 23 wherein the step a. includes generating a train of said incident pulses (68) at a first predetermined frequency and the step c. includes sensing at a sample rate equal to said first predetermined frequency modulated by a second predetermined frequency less than said first predetermined frequency.
References Cited (Backward Citations)
US3832900A
Cited
US3812422A
Cited
US3995212A
Cited
US4359902A
Cited
US5457990A
Cited
US5457394A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-11 | 2001-02-10 | 2001-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-11 | 2005-02-10 | 2005-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-11 | 2009-02-10 | 2009-08-12 | $7700.00 | Window Closed / Lapsed |