US4240294A
Expired / Lapsed
US
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Flow meter
Assignee: Individual
•
Filing: 1978-12-15
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Granted: 1980-12-23
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Expires: 1998-12-15
Abstract
Abstract A flow meter for the registration of pulsating liquid flows, and preferably for registration of small blood flows. The flow is measured by means of a differential pressure measurement over a first flow resistance (I) having a resistance R 1 . The flow meter includes a high pressure part in the form of a flow resistance (II) and a lower pressure part in the form of a flow resistance (III), and these have the resistances R 2 and R 3 , respectively. The resistances R 1 , R 2 and R 3 are selected so as to adjust the pressures on each side of the differential pressure meter in phase with each other independent of the frequency of the flow pulsations. Each resistance has a corresponding modulus of elasticity, and the resistances and moduli of elasticity are so related as to fulfill certain formulas.
Inventors
- 👤 Per-Olof Grande
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 16:35
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/05; G01F1/34; G01F1/36; G01F1/38
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
193 words
A flow meter for the registration of pulsating liquid flows, preferably for registration of small blood flows, the flow being measured by means of a differential pressure measurement over a first flow resistance (I) with the resistance R 1 , and the flow meter comprising, besides the flow resistance I, also a high pressure part in the form of a flow resistance (II) and a lower pressure part in the form of a flow resistance (III) with the resistances R 2 and R 3 , respectively, wherein the resistances R 1 , R 2 and R 3 are selected so as to adjust the pressures on each side of the differential pressure meter in phase with each other independent of the frequency of the flow pulsations, the flow resistances (I), (II) and (III) with the resistances R 1 , R 2 and R 3 , respectively, having moduli of elasticity k 1 , k 2 and k 3 , respectively, said factors being adapted to fulfill the following formula R.sub.2 /k.sub.2 =(R.sub.3 +R.sub.1)/k.sub.3 in which 1/k 1 is approximately equal to zero, that is the flow resistance material in the main is inelastic.
Claim 2
Dependent Claim
193 words
A flow meter for the registration of pulsating liquid flows, preferably for registration of small blood flows, the flow being measured by means of a differential pressure measurement over a first flow resistance (I) with the resistance R 1 , and the flow meter comprising, besides the flow resistance I, also a high pressure part in the form of a flow resistance (II) and a lower pressure part in the form of a flow resistance (III) with the resistances R 2 and R 3 , respectively, wherein the resistances R 1 , R 2 and R 3 are selected so as to adjust the pressures on each side of the differential pressure meter in phase with each other independent of the frequency of the flow pulsations, the flow resistances (I), (II) and (III) with the resistances R 1 , R 2 and R 3 , respectively, having moduli of elasticity k 1 , k 2 and k 3 , respectively, said factors being adapted to fulfill the following formula R.sub.2 /k.sub.2 =(R.sub.3 +R.sub.1)/k.sub.3 in which 1/k 1 is approximately equal to zero, that is the flow resistance material in the main is inelastic.
Claim 3
Dependent Claim
40 words
A flow meter according to claim 1, including an outer receptacle and a differential pressure meter mounted therein, both the outer receptacle and the interior of the pressure meter containing an inert not electrically conductive liquid having a low viscosity.
Claim 4
Dependent Claim
16 words
A flow meter according to claim 2, wherein the inert liquid has another density than water.
Claim 5
Dependent Claim
35 words
A flow meter according to claim 2 or 3, wherein the outer receptacle has an elastic wall portion which alters its shape with volume alterations so that the pressure in the outer receptacle remains constant.
Claim 6
Dependent Claim
40 words
A flow meter according to claim 2 or 3, wherein the outer receptacle also contains a smaller quantity of gas which compensates for the volume alteration of the liquid by which the pressure in the outer receptacle remains approximately constant.
Claim 7
Dependent Claim
33 words
A flow meter according to claim 1, 2 or 3 wherein the high pressure part (II) in the main has a volume which is equal to that of the low pressure part (III).
Claim 8
Dependent Claim
80 words
A flow meter according to claim 6, wherein the equal volume of the high pressure part and low pressure part (II, III) has been obtained by means of intermediate pieces with a large and a smaller, respectively, inner volume, the pressure part originally having the largest volume moreover having been reduced by means of a pierced insert mounted in a coupling tube of that part, which tube extends to the pressure meter, said insert preferably having a good heat conductivity.
Claim 9
Dependent Claim
38 words
A flow meter according to claim 1, 2 or 3 wherein the desired resistances are obtained by means of intermediate pieces which have depressions for membranes in contact with the flow, the pressure of which should be measured.
Claim 10
Dependent Claim
39 words
A flow meter according to claim 8, wherein the membranes transferring the pressure from the flow path to the differential pressure meter are double-walled, the membrane wall contacting the blood vessel being a part of the flow resistance (I).
Claim 11
Dependent Claim
38 words
A flow meter according to claim 8, wherein the membranes are elastic and at measurement of the blood flow the membrane walls positioned in the blood flow also consist of a blood-minded material, such as for instance siliconized-rubber.
Claim 12
Dependent Claim
49 words
A flow meter according to claim 1, 2 or 3 wherein the flow meter is for measurement of blood flow and wherein the inner surface of flow resistance (I) comprises a blood-minded material, for instance silicon-rubber, and is shaped without unevenesses damaging to the blood during the flowing thereof.
Claim 13
Dependent Claim
16 words
A flow meter according to claim 11, wherein flow resistance (I) forms a mountable part thereof.
Claim 14
Dependent Claim
18 words
A flow meter according to claim 2 wherein the receptacle is heat insulating and has a reflecting surface.
Claim 15
Dependent Claim
20 words
A flow meter according to claim 2, wherein the inert liquid in the outer receptacle has a temperature buffer capability.
Claim 16
Dependent Claim
193 words
A flow meter for the registration of pulsating liquid flows, preferably for registration of small blood flows, the flow being measured by means of differential pressure measurement over a first flow resistance (I) with the resistance R 1 , and the flow meter comprising, besides the flow resistance (I), also a high pressure part in the form of a flow resistance (II) and a low pressure part in the form of a flow resistance (III) with the resistances R 2 and R 3 , respectively, and wherein the resistances R 1 , R 2 and R 3 are selected so as to adjust the pressures on each side of the differential pressure meter in phase with each other independent of the frequency of the flow pulsations the flow resistances (I), (II) and (III), with the resistances R 1 , R 2 and R 3 , respectively, having moduli of elasticity k 1 , k 2 and k 3 , respectively which are adapted to fulfill the formula R.sub.2 =R.sub.1 +R.sub.3 if k.sub.2 =k.sub.3 in which 1/k 1 is approximately equal to zero, that is the flow resistance material in the main is inelastic.
Claim 17
Dependent Claim
193 words
A flow meter for the registration of pulsating liquid flows, preferably for registration of small blood flows, the flow being measured by means of differential pressure measurement over a first flow resistance (I) with the resistance R 1 , and the flow meter comprising, besides the flow resistance (I), also a high pressure part in the form of a flow resistance (II) and a low pressure part in the form of a flow resistance (III) with the resistances R 2 and R 3 , respectively, and wherein the resistances R 1 , R 2 and R 3 are selected so as to adjust the pressures on each side of the differential pressure meter in phase with each other independent of the frequency of the flow pulsations the flow resistances (I), (II) and (III), with the resistances R 1 , R 2 and R 3 , respectively, having moduli of elasticity k 1 , k 2 and k 3 , respectively which are adapted to fulfill the formula R.sub.2 =R.sub.1 +R.sub.3 if k.sub.2 =k.sub.3 in which 1/k 1 is approximately equal to zero, that is the flow resistance material in the main is inelastic.
References Cited (Backward Citations)
US3994166A
Cited
US4096746A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-23 | 1984-06-23 | 1984-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-23 | 1988-06-23 | 1988-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-23 | 1992-06-23 | 1992-12-23 | $7700.00 | Window Closed / Lapsed |