High-temperature optical liquid level sensor

• US 20070145309A1
• Filed: 12/15/2005
• Published: 06/28/2007
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Zhang, Wenwei
• Granted Patent: US 7,388,222 B2
• Time in Patent Office: Days
• US Class Current: 250/577
• CPC Class Codes: G01F 23/292 Light , e.g. infrared or ultraviolet
• CPC Class Codes: G01F 23/2925 using electrical detecting means
• CPC Class Codes: Y10S 250/90 Optical liquid level sensors

Abstract

The invention provides an optical liquid level sensor used to determine the level of a liquid within a vessel. The sensor includes two adjacent elongated optical elements, such as optical fibers, which connect a first end, or “sensing end”, to a second end, or “non-sensing end”. The sensing end includes an optical lens for sensing the level of a high temperature liquid, while the non-sensing end includes electronic components for processing optical signal data relating to the sensed liquid level. The ends are sufficiently separated by the elongated optical elements, such that high temperatures exerted on the sensing end when it is immersed in high-temperature liquid are not exerted on the non-sensing end. This configuration avoids the temperature degradation of the electronic components, thus extending the lifetime of the sensor.

Claims

1. An optical liquid level sensor which comprises:

a) an elongated optical transmitter element having a first end and a second end, for transmitting optical signals from its second end to its first end, and an adjacent elongated optical receiver element having a first end and a second end for receiving reflected optical signals at its first end and transmitting the reflected optical signals to its second end;

b) a coupler for holding together the first end of the optical transmitter element to the first end of the optical receiver element, to thereby form a coupled optical element end;

c) an optical lens on the coupled optical element end, which optical lens is capable of receiving optical signals from the second end of the optical transmitter element, forming reflected optical signals therefrom, and passing the reflected optical signals into the first end of the optical receiver element;

d) a light source at or near a second end of the optical transmitter element, which light source is capable of receiving outgoing signal information from a processor and transmitting outgoing optical signals to the optical lens via the optical transmitter element;

e) a photoreceiver at or near a second end of the optical receiver element, which photoreceiver is capable of receiving reflected optical signals from the optical receiver element, and which photoreceiver is capable of sending reflected signal information to a processor; and

f) a processor attached to the light source and to the photoreceiver, which processor is capable of transmitting outgoing signal information to the light source, receiving reflected signal information from the photoreceiver, and processing reflected signal information.

2. The sensor of claim 1 wherein the processor is capable of determining and/or analyzing the presence, absence, and/or level of a liquid within a vessel, when the optical lens is immersed in said vessel.

3. The sensor of claim 1 wherein each of the optical transmitter element and the optical receiver element comprise at least one optical fiber.

4. The sensor of claim 1 wherein each of the optical transmitter element and the optical receiver element comprise a glass rod.

5. The sensor of claim 1 wherein each of the optical transmitter element and the optical receiver element comprise a material having a melting and/or degradation temperature of about b 400°

C. or greater.

6. The sensor of claim 1 wherein each of the optical transmitter element and the optical receiver element independently comprise a silica, doped silica, glass, borosilicate, polyimide coated silica, polyimide coated borosilicate, sapphire or combinations thereof.

7. The sensor of claim 1 wherein the optical transmitter element and/or the optical receiver element comprise a borosilicate material.

8. The sensor of claim 1 wherein the coupler comprises a glass ring.

9. The sensor of claim 1 wherein the lens comprises a material having a melting and/or degradation temperature of about 400°

C. or greater.

10. The sensor of claim 1 wherein the lens comprises a silica, doped silica, glass, borosilicate, optical epoxy, polyimide coated silica, polyimide coated borosilicate, sapphire or combinations thereof.

11. The sensor of claim 1 wherein the lens comprises a borosilicate material.

12. The sensor of claim 1 wherein the lens comprises a pre-formed microlens attached to the coupled optical element end.

13. The sensor of claim 1 wherein the lens is printed on the coupled optical element end.

14. An optical liquid level sensor which comprises:

a) an elongated optical transmitter element having a first end and a second end, for transmitting optical signals from its second end to its first end, and an adjacent elongated optical receiver element having a first end and a second end for receiving reflected optical signals at its first end and transmitting the reflected optical signals to its second end, wherein each of the optical transmitter element comprise at least one optical fiber having a melting and/or degradation temperature of about 400°

C. or greater;

b) a glass ring coupler for holding together the first end of the optical transmitter element to the first end of the optical receiver element, to thereby form a coupled optical element end;

c) an optical lens on the coupled optical element end, which optical lens is capable of receiving optical signals from the second end of the optical transmitter element, forming reflected optical signals therefrom, and passing the reflected optical signals into the first end of the optical receiver element, which optical lens comprises a material having a melting and/or degradation temperature of about 400°

C. or greater;

d) a light emitting diode at or near a second end of the optical transmitter element, which light emitting diode is capable of receiving outgoing signal information from a processor and transmitting outgoing optical signals to the optical lens via the optical transmitter element;

e) a photodiode at or near a second end of the optical receiver element, which photodiode is capable of receiving reflected optical signals from the optical receiver element, and which photodiode is capable of sending reflected signal information to a processor; and

f) a processor attached to the light emitting diode and to the photodiode, which processor is capable of transmitting outgoing signal information to the light emitting diode, receiving reflected signal information from the photodiode, and processing reflected signal information.

15. A method of sensing the depth of a liquid which comprises:

I) providing an optical liquid level sensor which comprises;

a) an elongated optical transmitter element having a first end and a second end, for transmitting optical signals from its second end to its first end, and an adjacent elongated optical receiver element having a first end and a second end for receiving reflected optical signals at its first end and transmitting the reflected optical signals to its second end;

b) a coupler for holding together the first end of the optical transmitter element to the first end of the optical receiver element, to thereby form a coupled optical element end;

c) an optical lens on the coupled optical element end, which optical lens is capable of receiving optical signals from the second end of the optical transmitter element, forming reflected optical signals therefrom, and passing the reflected optical signals into the first end of the optical receiver element;

d) a light source at or near a second end of the optical transmitter element, which light source is capable of receiving outgoing signal information from a processor and transmitting outgoing optical signals to the optical lens via the optical transmitter element;

e) a photoreceiver at or near a second end of the optical receiver element, which photoreceiver is capable of receiving reflected optical signals from the optical receiver element, and which photoreceiver is capable of sending reflected signal information to a processor; and

f) a processor attached to the light source and to the photoreceiver, which processor is capable of transmitting outgoing signal information to the light source, receiving reflected signal information from the photoreceiver, and processing reflected signal information;

II) immersing at least a portion of the optical lens into a vessel, which vessel optionally contains a liquid;

III) sending outgoing signal information from the processor to the light source, thereby causing an outgoing optical signal to be transmitted from the light source to the optical lens via the optical transmitter element;

IV) forming reflected optical signals at the optical lens, and passing the reflected optical signals into the first end of the optical receiver element;

V) receiving the reflected optical signal into the photoreceiver from the optical receiver element;

VI) sending reflected signal information from the photoreceiver to the processor; and

VII) processing the reflected signal information via the processor.

16. The method of claim 15, further comprising the subsequent step of determining and/or analyzing the presence, absence, and/or level of liquid in the vessel.

17. The method of claim 15 wherein each of the optical transmitter element and the optical receiver element comprise at least one optical fiber.

18. The method of claim 15 wherein each of the optical transmitter element and the optical receiver element comprise a material having a melting and/or degradation temperature of about 400°

C. or greater.

19. The method of claim 15 wherein the coupler comprises a glass ring.

20. The method of claim 15 wherein the lens comprises a material having a melting and/or degradation temperature of about 400°

C. or greater.