Noninvasive measurement of fluid characteristics using reversibly deformed conduit

• US 20080011060A1
• Filed: 07/13/2006
• Published: 01/17/2008
• Est. Priority Date: 07/13/2006
• Status: Active Grant

• Current Assignee: Transonic Systems, Inc. (Measurement Innovations Corp.)
• Original Assignee: Lawrence C. Lynnworth
• Inventors: Lynnworth, Lawrence C.
• Granted Patent: US 7,481,114 B2
• Time in Patent Office: Days
• US Class Current: 73/64.53
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425

Abstract

An apparatus for determining a characteristic such as sound speed for a fluid in a tube comprises means for applying a force to cause a change in a transverse dimension of a segment of the tube, wherein the change in the transverse dimension is reversible, and means for launching and receiving ultrasonic signals. Ultrasonic signals propagate through the tube along paths of different lengths. At least one of the paths is located entirely within the segment having the changed transverse dimension. The applied force may cause the transverse dimension to change continuously or in discrete steps. Path length differences between the paths are determined, and transit times are determined for each of the ultrasonic signals. The characteristic is determined based on information comprising the path length differences and the transit times.

Claims

1. An apparatus for determining a characteristic of a fluid in a tube, the apparatus comprising:

(a) means for applying a force to cause a change in a transverse dimension of a segment of the tube, wherein the change in the transverse dimension is reversible; and

(b) means for launching and receiving ultrasonic signals, wherein a first ultrasonic signal propagates along a first path through the tube, the first path having a first path length, and a second ultrasonic signal propagates along a second path through the tube, the second path having a second path length, and wherein the first path length differs from the second path length and at least one of the first path and the second path is located entirely within the segment.

2. The apparatus of claim 1, wherein the first path and the second path are colinear.

3. The apparatus of claim 1, wherein the first path is parallel to the second path.

4. The apparatus of claim 1, wherein the first path is orthogonal to the second path.

5. The apparatus of claim 1, wherein the first path is orthogonal to the tube wall.

6. The apparatus of claim 1, wherein the means for applying a force comprises a micrometer spindle and a micrometer anvil.

7. The apparatus of claim 1, wherein the means for applying a force comprises a threaded rod and a datum frame.

8. The apparatus of claim 1, wherein the means for launching and receiving ultrasonic signals comprises a single transducer.

9. The apparatus of claim 1, wherein the means for launching and receiving ultrasonic signals comprises a first transducer and a second transducer.

10. The apparatus of claim 1, further comprising means for determining a path length difference between the first path length and the second path length.

11. The apparatus of claim 10, wherein the means for determining a path length difference comprises a micrometer scale.

12. The apparatus of claim 10, wherein the means for determining a path length difference comprises a spacer having a first groove and a second groove, wherein a first depth for the first groove differs from a second depth for the second groove.

13. The apparatus of claim 10, wherein the means for determining a path length difference comprises a linear variable differential transformer (LVDT).

14. The apparatus of claim 10, wherein the characteristic is determined based on information comprising the path length difference and a first transit time for the first ultrasonic signal and a second transit time for the second ultrasonic signal.

15. The apparatus of claim 1, wherein the characteristic is determined based on information comprising the first path length and the second path length and a first transit time for the first ultrasonic signal and a second transit time for the second ultrasonic signal.

16. A method for determining a characteristic of a fluid in a tube, the method comprising:

(a) applying a force to cause a change in a transverse dimension of a segment of the tube, wherein the change in the transverse dimension is reversible;

(b) propagating a first ultrasonic signal along a first path through the tube, the first path having a first path length;

(c) determining a first transit time for the first ultrasonic signal;

(d) propagating a second ultrasonic signal along a second path through the tube, the second path having a second path length, wherein the first path length differs from the second path length and at least one of the first path and the second path is located entirely within the segment; and

(e) determining a second transit time for the second ultrasonic signal.

17. The method of claim 16, further comprising:

(f) determining a path length difference between the first path length and the second path length; and

(g) determining the characteristic based on information comprising the path length difference and the first transit time and the second transit time.

18. The method of claim 16, wherein steps (b) and (c) precede step (a).

19. The method of claim 16 carried out in the order of claim 16.

20. The method of claim 16, wherein step (b) and step (d) occur at substantially the same time.

21. The method of claim 16, further comprising determining the characteristic based on information comprising the the first path length and the second path length and the first transit time and the second transit time.

22. A method for determining a characteristic of a fluid in a tube, the method comprising:

(a) applying a force to continuously change a transverse dimension of a segment of the tube, wherein a change in the transverse dimension caused by the applying of force is reversible;

(b) propagating plural ultrasonic signals along plural paths through the tube, wherein at least one of the plural paths is located entirely within the segment;

(c) determining plural dimensions for the segment wherein each of the plural dimensions is colinear with one or more of the plural paths;

(d) determining a transit time for two or more of the plural ultrasonic signals; and

(e) determining the characteristic based on information comprising the plural dimensions and the transit times.