Patent US3680377A successfully refreshed from Google Patents.
US3680377A
Expired / Lapsed
US
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Fluid flow meter
Assignee: HP Inc
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Filing: 1970-08-17
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Granted: 1972-08-01
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Expires: 1990-08-17
Abstract
Abstract A fluid is passed through first and second thermally conductive porous conduit elements spaced apart from one another along the path of fluid flow. A heater and a temperature sensor are mounted on each porous element and operated to maintain the two elements at constant preset differential temperatures. Flow rate of the fluid is indicated by the electrical power supplied to the heater on the second porous element to maintain the preset temperature differential. Temperature controlled metal cylinders surround the porous elements to insulate them from the adverse effects of the ambient temperature. A shaped conduit between the porous elements further minimizes heat loss from the fluid and improves measurement accuracy.
Inventors
- 👤 Gene E Lightner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:36
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
302 words
An apparatus for measuring the flow rate of a fluid along a path of travel comprising: means defining a first zone in said path of travel for electrically heating said fluid to a first predetermined constant temperature; means defining a second zone in said path of travel downstream from said first zone for electrically heating said fluid to a second predetermined constant temperature higher than said first predetermined constant temperature; said means defining said first zone and said means defining said second zone each including: an electrical heating element disposed in said path of fluid travel; an electrical temperature sensor disposed in said path of fluid travel; and circuit means responsive to said temperature sensor for controlling the power supplied to said electrical heating element to maintain the temperature of the fluid in the corresponding zone at a preset constant level; means for measuring the electrical power required to heat the fluid in said second zone to said second predetermined constant temperature, thereby to indicate the flow rate of fluid along said path of travel; and first and second means for insulating said first and second zones, respectively, to prevent heat loss from fluid flowing through said zones, each of said first and second insulating means including: thermally conductive means insulated from and at least partially surrounding the corresponding zone; an electrical heating element disposed in thermal contact with said thermally conductive means; an electrical temperature sensor disposed in thermal contact with said thermally conductive means and in spaced-apart relation with said last named electrical heating element; and circuit means responsive to said temperature sensor disposed in contact with said thermally conductive means for controlling said last named electrical heating element to maintain the temperature of said thermally conductive means the same as the temperature of the fluid in the corresponding zone.
Claim 2
Independent Claim
302 words
An apparatus for measuring the flow rate of a fluid along a path of travel comprising: means defining a first zone in said path of travel for electrically heating said fluid to a first predetermined constant temperature; means defining a second zone in said path of travel downstream from said first zone for electrically heating said fluid to a second predetermined constant temperature higher than said first predetermined constant temperature; said means defining said first zone and said means defining said second zone each including: an electrical heating element disposed in said path of fluid travel; an electrical temperature sensor disposed in said path of fluid travel; and circuit means responsive to said temperature sensor for controlling the power supplied to said electrical heating element to maintain the temperature of the fluid in the corresponding zone at a preset constant level; means for measuring the electrical power required to heat the fluid in said second zone to said second predetermined constant temperature, thereby to indicate the flow rate of fluid along said path of travel; and first and second means for insulating said first and second zones, respectively, to prevent heat loss from fluid flowing through said zones, each of said first and second insulating means including: thermally conductive means insulated from and at least partially surrounding the corresponding zone; an electrical heating element disposed in thermal contact with said thermally conductive means; an electrical temperature sensor disposed in thermal contact with said thermally conductive means and in spaced-apart relation with said last named electrical heating element; and circuit means responsive to said temperature sensor disposed in contact with said thermally conductive means for controlling said last named electrical heating element to maintain the temperature of said thermally conductive means the same as the temperature of the fluid in the corresponding zone.
Claim 3
Dependent Claim
16 words
The apparatus of claim 1 wherein each of said thermally conductive means is a metal tube.
Claim 4
Dependent Claim
38 words
The apparatus of claim 1, wherein the temperature sensors disposed in thermal contact with said thermally conductive means and the temperature sensors disposed in said path of fluid travel each include at least one temperature sensing semiconductor element.
Claim 5
Dependent Claim
41 words
The apparatus of claim 1, wherein the heating elements disposed in thermal contact with said thermally conductive means and the heating elements disposed in said path of fluid travel each include a transistor having a pair of main current carrying electrodes.
Claim 6
Dependent Claim
65 words
The apparatus of claim 4 wherein said means for measuring the electrical power required to heat the fluid in said second zone includes: means for indicating the current conducted between the main current carrying electrodes of the transistor disposed in the path of fluid travel in said second zone; and means for maintaining the voltage between said main current carrying electrodes at a constant level.
Claim 7
Dependent Claim
36 words
The apparatus of claim 1, further including thermally conductive conduit means disposed in thermal contact with said first insulating means for directing fluid along said path of travel from said first zone to said second zone.
Claim 8
Independent Claim
187 words
An apparatus for measuring the flow rate of a fluid along a path of travel comprising: means defining a first zone in said path of travel for electricalLy heating said fluid to a first predetermined constant temperature; means defining a second zone in said path of travel downstream from said first zone for electrically heating said fluid to a second predetermined constant temperature higher than said first predetermined constant temperature; said means defining said first zone and said means defining said second zone each including: porous thermally conductive means forming the path of fluid travel for transferring heat energy to said fluid; an electrical heating element and an electrical temperature sensor mounted in thermal contact with said porous means; circuit means responsive to said temperature sensor for controlling the power supplied to said electrical heating element to maintain the temperature of the fluid in the corresponding zone at a preset constant level; and means for measuring the electrical power required to heat the fluid in said second zone to said second predetermined constant temperature, thereby to indicate the flow rate of fluid along said path of travel.
Claim 9
Independent Claim
187 words
An apparatus for measuring the flow rate of a fluid along a path of travel comprising: means defining a first zone in said path of travel for electricalLy heating said fluid to a first predetermined constant temperature; means defining a second zone in said path of travel downstream from said first zone for electrically heating said fluid to a second predetermined constant temperature higher than said first predetermined constant temperature; said means defining said first zone and said means defining said second zone each including: porous thermally conductive means forming the path of fluid travel for transferring heat energy to said fluid; an electrical heating element and an electrical temperature sensor mounted in thermal contact with said porous means; circuit means responsive to said temperature sensor for controlling the power supplied to said electrical heating element to maintain the temperature of the fluid in the corresponding zone at a preset constant level; and means for measuring the electrical power required to heat the fluid in said second zone to said second predetermined constant temperature, thereby to indicate the flow rate of fluid along said path of travel.
Claim 10
Dependent Claim
18 words
The apparatus of claim 7, wherein each of said porous thermally conductive means is formed of sintered metal.
Claim 11
Dependent Claim
35 words
The apparatus of claim 7, wherein each heating element is mounted on an upstream portion of the corresponding porous means, and each temperature sensor is mounted on a downstream portion of the corresponding porous means.
References Cited (Backward Citations)
US2650496A
Cited
US2994222A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-01 | 1976-01-31 | 1976-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-01 | 1980-01-31 | 1980-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-01 | 1984-01-31 | 1984-08-01 | $7700.00 | Window Closed / Lapsed |