Passive Pressure Sensing

• US 20150260595A1
• Filed: 12/17/2014
• Published: 09/17/2015
• Est. Priority Date: 03/13/2014
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Montoya, James Daniel
• Granted Patent: US 9,625,338 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01L 1/162 using piezoelectric resonators
• CPC Class Codes: G01L 7/084 with mechanical transmitting or indicating means
• CPC Class Codes: G01L 9/0022 of a piezoelectric element
• CPC Class Codes: G01L 9/008 using piezoelectric devices piezoelectric resonators G01L9/0022; surface acoustic waves G01L9/0025

Abstract

A pressure sensor for sensing pressure of a fluid includes a diaphragm flexure and a crystal retaining flexure. The diaphragm flexure is designed to exert imparted force on the crystal retaining flexure. The imparted force is proportional to fluid pressure exerted on the diaphragm flexure. The pressure sensor further includes a resonator having opposing curved end portions connected to each other by a bridge section. A portion of the crystal retaining flexure is positioned between the diaphragm flexure and the resonator. The crystal retaining flexure is designed to exert a load on the resonator. The load results from the imparted force exerted on the crystal retaining flexure by the diaphragm flexure.

Claims

1. A pressure sensor for sensing pressure of a fluid, the pressure sensor comprising:

a diaphragm flexure;

a crystal retaining flexure, wherein the diaphragm flexure is designed to exert imparted force on the crystal retaining flexure and wherein the imparted force is proportional to fluid pressure exerted on the diaphragm flexure; and

a resonator having opposing curved end portions connected to each other by a bridge section, wherein a portion of the crystal retaining flexure is positioned between the diaphragm flexure and the resonator, and wherein the crystal retaining flexure is designed to exert a load on the resonator, the load resulting from the imparted force exerted on the crystal retaining flexure by the diaphragm flexure.

2. The pressure sensor of claim 1, wherein the diaphragm flexure is in contact with the crystal retaining flexure and wherein the crystal retaining flexure is in contact with the resonator.

3. The pressure sensor of claim 1, wherein the diaphragm flexure is designed to move toward the crystal retaining flexure in response to an increase in the fluid pressure, wherein the crystal retaining flexure is designed to move toward the resonator in response to an increase in the imparted force, and wherein the resonator is designed to oscillate at a resonant frequency in response to the load exerted onto the resonator.

4. The pressure sensor of claim 3, further comprising a chamber at least partially bounded by the diaphragm flexure, wherein the fluid pressure is exerted by a fluid contained in the chamber and wherein the fluid is isolated from the crystal retaining flexure and the resonator.

5. The pressure sensor of claim 4, further comprising a pressure head having a fluid inlet and a channel, wherein the channel extends between the fluid inlet and the chamber.

6. The pressure sensor of claim 5, wherein the diaphragm flexure, the crystal retaining flexure, the resonator, and at least a portion of the pressure head are positioned within a housing.

7. The pressure sensor of claim 4, wherein the fluid is a hydraulic fluid separated from an outside fluid that exerts external fluid pressure that is sensed by the pressure sensor.

8. The pressure sensor of claim 3, wherein the load exerted on the resonator is proportional to the imparted force exerted on the crystal retaining flexure.

9. The pressure sensor of claim 1, wherein the diaphragm flexure comprises a protrusion that is in contact with the crystal retaining flexure.

10. A system for measuring a pressure of a fluid, the system comprising:

a signal source;

a signal receiver; and

a pressure sensor comprising;

a diaphragm flexure;

a crystal retaining flexure, wherein the diaphragm flexure is designed to exert imparted force on the crystal retaining flexure, wherein the imparted force is proportional to fluid pressure exerted on the diaphragm flexure; and

a resonator having opposing curved end portions connected to each other by a bridge section, wherein a portion of the crystal retaining flexure is positioned between the diaphragm flexure and the resonator, and wherein the crystal retaining flexure is designed to exert a load on the resonator, the load resulting from the imparted force exerted on the crystal retaining flexure by the diaphragm flexure, and wherein the resonator is electrically coupled to the signal source and to the signal receiver.

11. The system of claim 10, wherein the crystal retaining flexure is coupled to a ground potential electrode of the resonator and wherein a positive potential is coupled to a second electrode of the resonator.

12. The system of claim 10, wherein the resonator is a quartz resonator and wherein the signal source is configured to vary a frequency of a signal provided to the resonator.

13. The system of claim 10, wherein the resonator is a ceramic resonator and wherein the signal source is configured to vary a frequency of a signal provided to the resonator.

14. The system of claim 10, wherein the pressure sensor further comprises a chamber at least partially bounded by the diaphragm flexure, wherein the fluid pressure is exerted by a fluid contained in the chamber, wherein the fluid is isolated from the crystal retaining flexure and the resonator, and wherein the load exerted on the resonator is proportional to the imparted force exerted on the crystal retaining flexure.

15. The system of claim 14, wherein the pressure sensor further comprises a pressure head having a fluid inlet and a channel and wherein the channel extends between the fluid inlet and the chamber.

16. The system of claim 14, wherein the fluid is a hydraulic fluid separated from an outside fluid that exerts external fluid pressure that is sensed by the pressure sensor.

17. A method for measuring a pressure of a fluid, the method comprising:

generating a signal by a signal source;

receiving the signal by a signal receiver through a pressure sensor;

processing the signal to determine the pressure sensed by the pressure sensor, the pressure sensor comprising;

a diaphragm flexure;

a crystal retaining flexure; and

a resonator having opposing curved end portions connected to each other by a bridge section, wherein a portion of the crystal retaining flexure is positioned between the diaphragm flexure and the resonator, wherein the crystal retaining flexure is designed to exert a load on the resonator, the load resulting from an imparted force exerted on the crystal retaining flexure by the diaphragm flexure, and wherein receiving the signal through the pressure sensor comprises receiving the signal through the resonator.

18. The method of claim 17, wherein the pressure sensor further comprises a chamber at least partially bounded by the diaphragm flexure, wherein a fluid pressure is exerted by a fluid contained in the chamber, wherein the fluid is isolated from the crystal retaining flexure and the resonator.

19. The method of claim 17, further comprising varying a frequency of the signal by the signal source.

20. The method of claim 19, wherein processing the signal includes determining a voltage level of the signal after the signal is received by the signal receiver.