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US5343109A
Expired / Lapsed
US
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Ultrasonic transducer for measuring the travel time of ultrasonic pulses in a gas
Assignee: Siemens AG
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Filing: 1993-03-08
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Granted: 1994-08-30
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Expires: 2013-03-08
Abstract
Abstract An ultrasonic transducer for measuring the travel time of ultrasonic pulses in a gas, in particular for a gas flow rate meter, includes a piezoelectric radial oscillator, which is preferably formed a piezoceramic and which has two sides and electrodes each being disposed on a respective one of the sides for receiving a spike pulse voltage. A first adaptation layer is applied to one of the sides of the radial oscillator. The first adaptation layer has a thickness being less than one-fourth of a characteristic wavelength of the transducer. A second adaptation layer is applied to the first adaptation layer. The second adaptation layer also has a thickness being less than one-fourth of the characteristic wavelength of the transducer. A damping body is mounted on the other of the sides of the radial oscillator. The radial oscillator and the adaptation layers form a sandwich executing a thickness oscillation as a consequence of a radial-thickness coupling, as soon as the spike pulse voltage is applied. The characteristic wavelength of the transducer is a wavelength resulting from natural resonance in the thickness oscillation.
Inventors
- 👤 Thomas Mockl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:23
CPC Classifications
G; G10; G10K; G10K9/00; G10K9/12; G10K9/122; B; B06; B06B; B06B1/00; B06B1/02; B06B1/06; B06B1/0644; B06B1/0662; B06B1/067; G01; G01F; G01F1/00; G01F1/66; G01F1/662; G01N; G01N2291/00; G01N2291/02; G01N2291/028; G01N2291/02836
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
187 words
An ultrasonic transducer for measuring the travel time of ultrasonic pulses in a gas, comprising: a) a piezoelectric radial oscillator having two sides, electrodes each being disposed on a respective one of said sides for receiving a spike pulse voltage; b) a first adaptation layer being applied to one of said sides of said radial oscillator, said first adaptation layer having a thickness d A less than one-fourth of a characteristic wavelength of the transducer; c) a second adaptation layer applied to said first adaptation layer, said second adaptation layer also having a thickness d B less than one-fourth of the characteristic wavelength of the transducer, and said thicknesses d A and d B following the statement d A +d B ≈λ/4; d) a damping body mounted on the other of said sides of said radial oscillator; and e) said radial oscillator and said adaptation layers forming a sandwich executing a thickness oscillation as a consequence of a radial-thickness coupling, as soon as the spike pulse voltage is applied, and the characteristic wavelength of the transducer being a wavelength resulting from natural resonance in the thickness oscillation.
Claim 2
Dependent Claim
187 words
An ultrasonic transducer for measuring the travel time of ultrasonic pulses in a gas, comprising: a) a piezoelectric radial oscillator having two sides, electrodes each being disposed on a respective one of said sides for receiving a spike pulse voltage; b) a first adaptation layer being applied to one of said sides of said radial oscillator, said first adaptation layer having a thickness d A less than one-fourth of a characteristic wavelength of the transducer; c) a second adaptation layer applied to said first adaptation layer, said second adaptation layer also having a thickness d B less than one-fourth of the characteristic wavelength of the transducer, and said thicknesses d A and d B following the statement d A +d B ≈λ/4; d) a damping body mounted on the other of said sides of said radial oscillator; and e) said radial oscillator and said adaptation layers forming a sandwich executing a thickness oscillation as a consequence of a radial-thickness coupling, as soon as the spike pulse voltage is applied, and the characteristic wavelength of the transducer being a wavelength resulting from natural resonance in the thickness oscillation.
Claim 3
Dependent Claim
17 words
The ultrasonic transducer according to claim 1, wherein said piezoelectric radial oscillator is formed of a piezoceramic.
Claim 4
Dependent Claim
34 words
The ultrasonic transducer according to claim 1, wherein said first adaptation layer is in the form of a cup having a bottom, and said radial oscillator is disposed on said bottom of said cup.
Claim 5
Dependent Claim
16 words
The ultrasonic transducer according to claim 3, wherein said cup is filled with said damping body.
Claim 6
Dependent Claim
20 words
The ultrasonic transducer according to claim 3, wherein said cup has a flattened surface in the vicinity of said bottom.
Claim 7
Dependent Claim
18 words
The ultrasonic transducer according to claim 1, including a third adaptation layer disposed over said second adaptation layer.
Claim 8
Dependent Claim
45 words
The ultrasonic transducer according to claim 1, wherein said thickness d A of said first adaptation layer is selected as λ/8≦d.sub.A <λ/4, said thickness d B of said second adaptation layer is selected as λ/8≦d.sub.B <λ/4, and λ is the wavelength of the thickness oscillation.
Claim 9
Dependent Claim
28 words
The ultrasonic transducer according to claim 7, wherein said thicknesses d A and d B of said first and second adaptation layers follow the statement: d.sub.A +d.sub.B ≈λ/4.
Claim 10
Dependent Claim
38 words
The ultrasonic transducer according to claim 7, wherein said thicknesses d A and d B of said first and second adaptation layers and the thickness d k of said radial oscillator follow the statement: d.sub.A +d.sub.B +d.sub.K ≈λ/2.
Claim 11
Dependent Claim
38 words
The ultrasonic transducer according to claim 8, wherein said thicknesses d A and d B of said first and second adaptation layers and the thickness d k of said radial oscillator follow the statement: d.sub.A +d.sub.B +d.sub.K ≈λ/2.
Claim 12
Dependent Claim
21 words
The ultrasonic transducer according to claim 1, wherein said first adaptation layer is a layer of glass microbeads in epoxy resin.
Claim 13
Dependent Claim
16 words
The ultrasonic transducer according to claim 1, wherein said second adaptation layer is an open-cell foam.
Claim 14
Dependent Claim
35 words
The ultrasonic transducer according to claim 1, including an electric excitation circuit for applying the spike pulse voltage to said electrodes, said electric excitation circuit including a capacitor discharging to said electrodes upon being activated.
Claim 15
Dependent Claim
34 words
The ultrasonic transducer according to claim 1, including an evaluation circuit evaluating at most a first three half-waves of each of the ultrasonic pulses tripped upon excitation, after each pulse passes through the gas.
Claim 16
Dependent Claim
16 words
The ultrasonic transducer according to claim 1, wherein a characteristic transducer frequency is approximately 200 kHz.
Claim 17
Dependent Claim
166 words
An ultrasonic transducer for measuring the travel time of ultrasonic pulses in a gas, comprising: a) a piezoelectric radial oscillator having two sides, electrodes each being disposed on a respective one of said sides for receiving a spike pulse voltage; b) a first adaptation layer applied to one of said sides of said radial oscillator, said first adaptation layer having a thickness d A defined as d.sub.A <0.2λ, where λ is a characteristic wavelength of the transducer; c) a second adaptation layer applied to said first adaptation layer, said second adaptation layer having a thickness d B defined as d.sub.B <0.2λ; d) a damping body mounted on the other of said sides of said radial oscillator; and e) said radial oscillator and said adaptation layers forming a sandwich executing a thickness oscillation as a consequence of a radial-thickness coupling, as soon as the spike pulse voltage is applied, and the characteristic wavelength of the transducer being a wavelength resulting from natural resonance in the thickness oscillation.
Claim 18
Dependent Claim
166 words
An ultrasonic transducer for measuring the travel time of ultrasonic pulses in a gas, comprising: a) a piezoelectric radial oscillator having two sides, electrodes each being disposed on a respective one of said sides for receiving a spike pulse voltage; b) a first adaptation layer applied to one of said sides of said radial oscillator, said first adaptation layer having a thickness d A defined as d.sub.A <0.2λ, where λ is a characteristic wavelength of the transducer; c) a second adaptation layer applied to said first adaptation layer, said second adaptation layer having a thickness d B defined as d.sub.B <0.2λ; d) a damping body mounted on the other of said sides of said radial oscillator; and e) said radial oscillator and said adaptation layers forming a sandwich executing a thickness oscillation as a consequence of a radial-thickness coupling, as soon as the spike pulse voltage is applied, and the characteristic wavelength of the transducer being a wavelength resulting from natural resonance in the thickness oscillation.
Claim 19
Dependent Claim
28 words
The ultrasonic transducer according to claim 16, wherein said thicknesses d A and d B of said first and second adaptation layers follow the statement: d.sub.A +d.sub.B ≦λ/4.
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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) | 1997-08-29 | 1998-02-28 | 1998-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-29 | 2002-02-28 | 2002-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-29 | 2006-02-28 | 2006-08-30 | $7700.00 | Window Closed / Lapsed |