OPTICAL LIQUID LEVEL SENSOR

• US 20140014777A1
• Filed: 07/09/2013
• Published: 01/16/2014
• Est. Priority Date: 07/11/2012
• Status: Active Grant

• Current Assignee: Airbus Helicopters Deutschland Gmbh (Airbus SE)
• Original Assignee: Eurocopter Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (European Aeronautic Defence and Space Company EADS NV)
• Inventors: Kreitmair-Steck, Wolfgang, Singer, Frank
• Granted Patent: US 9,116,029 B2
• Time in Patent Office: Days
• US Class Current: 244/135.R
• CPC Class Codes: B64D 37/005 Accessories not provided for in the groups B64D37/02 - B64D37/28
• CPC Class Codes: G01F 23/2845 for discrete levels G01F23/288, G01F23/292 take precedence
• CPC Class Codes: G01F 23/2921 for discrete levels
• CPC Class Codes: G01F 23/2927 for several discrete levels, e.g. with more than one light-conducting sensing element

Abstract

An optical level sensor (1) includes: mounting means (11) mounting the sensor (1) to a ceiling of the tank (9); a sensor tube (12, 12.1) provided with support and guidance elements (4) extending with at least three radially distributed positions inside the tank (9) and which collect support and guide optical fibers (3, 3.3, 3.4) to different heights of the tank (9), with each optical fiber (3) having a number of input sides (3.3) and a number of turns forming sensor heads between two input sides (3.3), for a different level (19); the corresponding support and guidance element (4) bending the fiber (3, 3.3, 3.4) in turns forming sensor heads of a small radius r around at least one corresponding guideway (4.3).

Claims

1. An optical level sensor for detection of a current liquid level inside a tank, said sensor being mounted to the tank, said sensor comprising:

a light source, a light detector with a processing unit, and optical fibers, said optical fibers comprising each at least one input side, assigned to the light source and reaching from the light source into the tank, and at least one output side, assigned to the processing unit via the light detector and reaching from inside said container or tank to the light detector, wherein the optical level sensor also includes;

mounting means for mounting the sensor to a ceiling of the tank; and

a sensor tube attached to the tank and having a housing sealed by sealing means to the tank above the liquid level and a bottom surface below the liquid level;

the sensor tube being provided with support and guidance elements extending with at least three radially distributed positions inside the tank and which collect support and guide optical fibers to different heights of the tank, with each optical fiber having a number of input sides and a number of turns forming sensor heads between two input sides, for a different level;

each optical fiber being guided in its half-length through a corresponding support and guidance element, with the corresponding support and guidance element bending the fiber in turns forming the sensor heads of a small radius r around at least one corresponding guideway of the corresponding support and guidance element.

2. An optical level sensor according to claim 1, wherein the number of optical fibers is chosen with at least:

50, 100, 1000 optical fibers provided for sensing different liquid levels.

3. An optical level sensor according to claim 2, wherein the input side of the optical fibers and the output sides of the optical fibers are collected in groups respectively.

4. An optical level sensor according to claim 3, wherein a collection of input sides of groups of optical fibers is fed collectively by a homogeneous planar light source.

5. An optical level sensor according to claim 3, wherein a collection of output sides of groups of optical fibers are sensed collectively by a Charged Coupled Device (CCD) as light detector.

6. An optical level sensor according to claim 1, wherein a material of the optical fibers is glass or plastic and the optical fibers have a diameter between 0.1 mm and 1.0 mm.

7. An optical level sensor according to claim 1, wherein a material of the support and guidance elements is plastic or metal.

8. An optical level sensor according to claim 1, wherein at least 50, 100, 1000 sensor heads are assembled in order to allow for detection of at least 50, 100, 1000 different liquid levels.

9. An optical level sensor according to claim 1, wherein a reference fiber is provided as a reference for the light intensity from a fiber which is in air exclusively.

10. An optical level sensor according to claim 1, wherein a spacing element is provided between the support and guidance elements and a spiral spring is provided in sensor tube so that the radial elements and spacing elements are compressed with the spiral spring.

11. An optical level sensor according to claim 1, wherein the turns forming sensor heads of optical fibers are arranged outside the fiber collecting sensor tube.

12. An optical level sensor according to claim 1, wherein the sensor tube is in the form of a caging basket, and the support and guidance elements with the fibers are completely inside the caging basket.

13. An optical level sensor according to claim 1, wherein the sealing means between the housing and the tank include at least one transparent window forming an optical filter.

14. An optical level sensor according to claim 13, wherein the sealing means extend between the inside of the tank and at least one light source, light detector and processing unit, so that at least one transparent window is forming at least one of:

a sealed transparent output window for optically filtering light from the light source and a sealed transparent input window for optically filtering light to the light detector.

15. An aircraft having a tank for gas and the tank having at least one optical level sensor according to claim 1, wherein the aircraft is a rotary wing aircraft having onboard sensing electronics connected to the optical level sensor for determining an exact current level of liquid inside the tank in a consuming process of liquid by the rotary wing aircraft.