Pressure or fluid level sensor

• US 5,303,586 A
• Filed: 01/22/1993
• Issued: 04/19/1994
• Est. Priority Date: 01/22/1993
• Status: Expired due to Fees

• Current Assignee: Wayne State University
• Original Assignee: Wayne State University
• Inventors: Tang, Qingfeng, Zhao, Yang
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Worth, W. Morris
• Application Number:
  US08/007,672
• Time in Patent Office: 452 Days
• Field of Search: 73/293, 73/299, 73/302, 250/577, 250/900, 250/904, 250/907
• US Class Current: 73/293
• CPC Class Codes: G01F 23/164 using a diaphragm, bellow as transmitting element
• CPC Class Codes: G01F 23/18 Indicating, recording or alarm devices actuated electrically
• CPC Class Codes: G01F 23/292 Light , e.g. infrared or ultraviolet
• CPC Class Codes: G01L 11/025 using a pressure-sensitive optical fibre
• CPC Class Codes: Y10S 250/90 Optical liquid level sensors
• CPC Class Codes: Y10S 250/904 with single light guide element to guide light in a continuous path

Abstract

A moveable body, cladding medium, and fiber are arranged to form a sensor suitable for use in monitoring changes in liquid, fluid, and material level and changes in pressure. The moveable body moves in response to changes in pressure or force. Movement of the body causes a change in the length of cladding medium surrounding an optical fiber. As the extent of cladded fiber length changes, the intensity of light transmitted through the fiber also changes.

Claims

1. A sensor, adaptable for use in monitoring the level of fluid or material in a container, comprising:

a) a barrel having spaced apart first and second ends and a piston slidably received in said barrel;

b) said piston having one end facing said first end of said barrel and responsive to force exerted thereon by a material or fluid in a container in communication with said barrel and adjacent said first end of said barrel;

c) a reservoir open to said second end of said barrel and containing an optical fiber and a cladding medium surrounding said fiber;

said piston serving as a free floating barrier separating the material or fluid in the container and said cladding medium in the reservoir, said piston, reservoir and barrel constructed and arranged so as to permit said piston to be urged toward said second end of said barrel as the force exerted by the fluid or material in the container increases, and to be urged toward said first end of said barrel as the force decreases, whereby in response to movement of said piston, the amount of said cladding medium in said reservoir changes, causing the level of said cladding medium surrounding said fiber to change; and

d) a light source at one end of said optical fiber and indicating means for sensing optical transmission through said fiber;

said fiber, light source, and indicating means constructed and arranged so that changes in the level of said cladding medium modulate the transmission of light through said fiber as sensed by said indicating means.

2. The sensor according to claim 1, wherein said cladding medium is mercury or alcohol.

3. The sensor according to claim 1, wherein said optical fiber is of glass or plastic.

4. The sensor according to claim 1, wherein said optical fiber is coiled within said reservoir.

5. A sensor, adaptable for use in monitoring the level of fluid or material in a container, comprising:

a) a body in the form of free floating piston having first and second opposed major surfaces, said body constructed and arranged to respond to force exerted by a material of fluid in said container at said first surface;

b) a reservoir containing an optical fiber and cladding medium surrounding said optical fiber, said reservoir open to said second major surface of said body;

said body serving as a free floating barrier separating the material or fluid in the container from said cladding medium in said reservoir and being responsive and subject only to forces exerted by the material or fluid in the container and said cladding medium in said reservoir;

c) said body and reservoir constructed and arranged so that as the force exerted on said first surface changes, said body moves so as to cause the level of said cladding medium surrounding said fiber to change; and

d) a light source at one end of said fiber and indicating means for sensing optical transmission through said fiber;

said fiber, light source, and indicating means constructed and arranged so that changes in the level of said cladding medium modulate the transmission of light through said fiber as sensed by said indicating means.

6. The sensor according to claim 5, wherein said cladding medium is mercury or alcohol.

7. The sensor according to claim 5, wherein said optical fiber is of glass or plastic.

8. The sensor according to claim 5, wherein said optical fiber is coiled within said reservoir.

9. A sensor, adaptable for use in monitoring the level of fluid or material in a container, comprising:

a) a body in the form of a free floating piston having first and second opposed major surfaces, said piston constructed and arranged to respond to force exerted by a material or fluid at said first surface;

b) a reservoir containing at least two or more optical fibers and cladding medium surrounding each one of said optical fibers, said reservoir open to said second major surface of said body;

said body serving as a free floating barrier separating the material or fluid in the container from said cladding medium in said reservoir and being responsive and subject only to forces exerted by the material or fluid in the container and said cladding medium in said reservoir;

c) said body and reservoir constructed and arranged so that as the force exerted on said first surface changes, said body moves so as to cause the level of said cladding medium surrounding each one of said optical fibers to change; and

d) a light source at one end of each one of said optical fibers and indicating means for sending optical transmission;

each one of said optical fibers, light source, and indicating means constructed and arranged so that changes in the level of said cladding medium modulate the transmission of light through each one of said optical fibers as sensed by said indicating means.

10. The sensor according to claim 9, wherein the cladding medium is mercury or alcohol.

11. The sensor according to claim 9, wherein each one of said fibers is of glass or plastic.