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US3798967A
Expired / Lapsed
US
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Probe for measuring the flow of liquids
Assignee: US Philips Corp
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Filing: 1972-04-13
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Granted: 1974-03-26
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Expires: 1992-04-13
Abstract
Abstract A probe for measuring flow rates of liquids whereby the liquid is locally heated by high-frequency heating and the temperature increase is sensed, the temperature increase being a measure of the flow rate.
Inventors
- 👤 A Gieles
- 👤 G Somers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:04
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/026; A61B5/0275; A61B5/028; G; G01; G01F; G01F1/00; G01F1/68; G01P; G01P5/00; G01P5/10; G01P5/12
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
122 words
A probe for use in measuring the flow rate of a liquid through a duct comprising a cage through which liquid may flow, a coaxial cable extending from without to within said cage the outer jacket of said cable being connected to said cage, an electrode positioned within said cage and connected to the inner core of said cable, and a temperature dependent resistance electrically connected between said cage and the inner core of said cable, whereby said probe may be supplied with high frequency electrical power via said cable thus creating an energy field within said cage which heats liquid flowing through said cage, and whereby said resistance is positioned to measure the temperature of liquid flowing out of said cage.
Claim 2
Dependent Claim
122 words
A probe for use in measuring the flow rate of a liquid through a duct comprising a cage through which liquid may flow, a coaxial cable extending from without to within said cage the outer jacket of said cable being connected to said cage, an electrode positioned within said cage and connected to the inner core of said cable, and a temperature dependent resistance electrically connected between said cage and the inner core of said cable, whereby said probe may be supplied with high frequency electrical power via said cable thus creating an energy field within said cage which heats liquid flowing through said cage, and whereby said resistance is positioned to measure the temperature of liquid flowing out of said cage.
Claim 3
Dependent Claim
25 words
A probe as in claim 1 further characterized by a second temperature dependent resistance positioned to measure the temperature of liquid flowing into said cage.
Claim 4
Dependent Claim
13 words
A probe as in claim 2 wherein said electrode is an electromagnetic radiator.
Claim 5
Dependent Claim
18 words
A probe as in claim 1 wherein said liquid is blood and said duct is a blood vessel.
Claim 6
Dependent Claim
255 words
Apparatus for measuring the flow rate of a liquid through a duct, comprising a cage through which liquid may flow, a coaxial cable extending from without to within said cage, the outer jacket of said cable being connected to said cage, an electrode positioned centrally within said cage and connected to the inner core of said cable, a first choke and a first temperature dependent resistance electrically connected in series between said cage and the inner core of said cable and positioned within said cage to measure the temperature of liquid flowing out of said cage, a second temperature dependent resistance positioned within said cage to measure the temperature of liquid flowing into said cage, one end of said second resistance being electrically connected to the jacket of said cable and the other end being available external to said cage, a second choke, one end of said second choke being electrically connected to the core of said cable, a high frequency power source connected to the end of said cable external to said cage, and a resistance measuring circuit electrically connected between the externally available end of said second resistance and the other end of said second choke to measure the difference in temperature between liquid flowing into and out of said cage, whereby said power source produces an energy field within said cage thus heating liquid flowing through said cage the difference in temperature thereof at constant heating being proportional to the flow rate of the liquid, said difference being measured by said circuit.
Claim 7
Dependent Claim
255 words
Apparatus for measuring the flow rate of a liquid through a duct, comprising a cage through which liquid may flow, a coaxial cable extending from without to within said cage, the outer jacket of said cable being connected to said cage, an electrode positioned centrally within said cage and connected to the inner core of said cable, a first choke and a first temperature dependent resistance electrically connected in series between said cage and the inner core of said cable and positioned within said cage to measure the temperature of liquid flowing out of said cage, a second temperature dependent resistance positioned within said cage to measure the temperature of liquid flowing into said cage, one end of said second resistance being electrically connected to the jacket of said cable and the other end being available external to said cage, a second choke, one end of said second choke being electrically connected to the core of said cable, a high frequency power source connected to the end of said cable external to said cage, and a resistance measuring circuit electrically connected between the externally available end of said second resistance and the other end of said second choke to measure the difference in temperature between liquid flowing into and out of said cage, whereby said power source produces an energy field within said cage thus heating liquid flowing through said cage the difference in temperature thereof at constant heating being proportional to the flow rate of the liquid, said difference being measured by said circuit.
Claim 8
Dependent Claim
12 words
Apparatus as in claim 5 wherein said electrode is an electromagnetic radiator.
Claim 9
Dependent Claim
34 words
Apparatus as in claim 5 including means for controlling the output of said power source to produce a substantially constant temperature difference, the flow rate of said liquid being proportional to said controlled output.
Claim 10
Dependent Claim
17 words
Apparatus as in claim 5 wherein the liquid is blood and the duct is a blood vessel.
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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) | 1977-03-25 | 1977-09-24 | 1978-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-25 | 1981-09-24 | 1982-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-25 | 1985-09-24 | 1986-03-26 | $7700.00 | Window Closed / Lapsed |