LIGHT SENSING CONTACTLESS FUEL LEVEL SENSOR

• US 20090038395A1
• Filed: 08/08/2007
• Published: 02/12/2009
• Est. Priority Date: 08/08/2007
• Status: Active Grant

• Current Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Aikman, Steven, Roth, Robert A.
• Granted Patent: US 7,677,098 B2
• Time in Patent Office: Days
• US Class Current: 73/313
• CPC Class Codes: G01F 23/366 using optoelectrically actuated indicating means

Abstract

A contactless, sealed fuel level sensor for determining a fuel level in a fuel tank and producing a level indicative signal includes a frame, a cover, a float arm, a float and a light-responsive sensor. The frame is configured to have a cavity formed therein. The cover is connected to the frame to enclose the cavity. The float arm is coupled to one of the frame or cover. The float is connected to the float arm and configured such that the float moves the float arm as a level of fuel increases and decreases in the fuel tank. The light-responsive sensor is configured to generate a fuel level signal indicative of a fuel level in the fuel tank based on the movement of the float arm. The fuel level sensor may also include a light source such as a light emitting diode (LED). The light-responsive sensor may be a single photoelectric sensor located in the sealed cavity, or an array of photoelectric sensors located in the sealed cavity. The fuel level sensor may also include a rotatable hub connected to the float arm for movement as the arm moves and where rotation of the hub varies an amount of light impinging on the photoelectric sensor. The light responsive sensor may also include a CMOS sensor located in the sealed cavity. The light responsive sensor may also include a digital, optical-based displacement encoder mounted on the float arm used in combination with a rotary scale applied to the cover opposite the encoder.

Claims

1. A sealed fuel level sensor for a fuel tank comprising:

a frame having a cavity therein;

a cover connected to said frame to enclose said cavity;

a float arm coupled to one of said frame and said cover;

a float connected to said float arm and configured such that said float moves said float arm as a level of fuel increases and decreases in the fuel tank; and

a light-responsive sensor configured to generate a fuel level signal indicative of a fuel level in the fuel tank based on the movement of said float arm.

2. The fuel level sensor of claim 1 further including a light source comprising a light-emitting diode (LED) coupled to said float arm for movement therewith along a path, and wherein said cover comprises translucent material configured to allow light emitted from said LED to enter said cavity, said light-responsive sensor including a photoelectric sensor disposed in said cavity and arranged to receive light from said LED having an intensity that is variable as a function of said float arm movement along said path.

3. The fuel level sensor of claim 2 further including an optical fiber disposed on an interior surface of said cover facing said cavity and placed in registration with said path configured to carry light emitted from said LED to said photoelectric sensor.

4. The fuel level sensor of claim 2 further including a mechanical stop projecting from an exterior surface of said cover and arranged such that said float arm abuts said stop at a predetermined fuel level in said fuel tank, said mechanical stop and said float arm each comprising electrically conductive material, said fuel level sensor further including a circuit configured to detect when said float arm abuts said stop and to measure the fuel level signal, said circuit further configured to calibrate said measured fuel level signal with said predetermined fuel level.

5. The fuel level sensor of claim 2 wherein said frame includes a boss projecting through said cavity towards said cover, said boss including a cylindrical through bore having an axis, said float arm including a proximal portion configured to be inserted through said through bore wherein said float arm movement comprises pivotal movement about said axis.

6. The fuel level sensor of claim 5 further including a retention element configured for attachment proximate a free end of said proximal portion of said float arm so as to inhibit removal of said float arm from said cylinder bore.

7. The fuel level sensor of claim 1 further including a light source comprising a light-emitting diode (LED) coupled to said float arm for movement therewith along a path, and wherein said cover comprises translucent material configured to allow light emitted from said LED to enter said cavity, said light-responsive sensor including a plurality of photoelectric sensors disposed in said cavity and arranged in correspondence to and in registration with said path.

8. The fuel level sensor of claim 1 wherein said light-responsive sensor includes digital displacement encoder connected to said float arm for movement therewith along a path, said fuel level sensor further including indicia on said cover corresponding to said path and configured to be read by said displacement encoder, said encoder generating an electrical signal indicative of said movements.

9. The fuel level sensor of claim 1 wherein

said frame includes a boss projecting therefrom into said cavity towards said cover, said boss including a cylindrical through-bore having an axis, said boss comprising translucent material;

said frame further includes a support projecting therefrom into said cavity towards said cover, said support including a mounting surface;

a light source;

said light-responsive sensor includes a photoelectric sensor disposed on said mounting surface so as to face said boss;

said fuel level sensor further including a hub disposed in said through bore, said hub having a main cylindrical body portion with a first, outside diameter, said hub further having a retaining flange extending from said cylindrical body portion at a first end thereof, said retaining flange having a second, outside diameter greater than a third diameter of said cylindrical through-bore so as to retain said hub in said through bore, said hub having a first, light-source recess at said first end thereof configured to receive said light source, said hub further having a second recess formed at a second end thereof axially opposite said first end configured to receive and retain a proximal portion of said float arm such that said movement of said float arm causes rotation of said hub in said cylindrical bore;

wherein said cylindrical body further includes an opening through an outer surface thereof in light communication with said light-source recess, said opening configured in size and shape to vary an amount of light passing out of said opening and into a line-of-sight to be received by said photoelectric sensor as a function of a rotational position of said hub.

10. The fuel level sensor of claim 9 wherein said light source comprises a light emitting diode (LED).

11. The fuel level sensor of claim 9 wherein said hub further includes a keying feature at said second end configured to establish an orientation of said float arm with a predetermined angular orientation of said hub.

12. The fuel level sensor of claim 9 wherein said opening has a triangular geometry.

13. The fuel level sensor of claim 1

said frame includes a boss projecting therefrom into said cavity towards said cover, said boss including a cylindrical through-bore having an axis, said boss comprising translucent material;

a light source disposed in said cavity configured to direct emitted light towards said translucent boss;

said light-responsive sensor including a CMOS sensor disposed in said cavity proximate to and facing said translucent boss;

said fuel level sensor further including a hub disposed in said through bore, said hub having a main cylindrical body portion with a first, outside diameter, said hub further having a retaining flange extending from cylindrical body portion at a first end thereof, said retaining flange having a second, outside diameter greater than a third diameter of said cylindrical through-bore so as to retain said hub in said through-bore, said hub further having a second recess formed at a second end thereof axially opposite said first end configured to receive and retain a proximal portion of said float arm such that said movement of said float arm causes rotation of said hub in said cylindrical bore;

wherein said cylindrical body further includes indicia on an outer surface thereof configured to interact with light from said light source to modulate light that is received by said CMOS sensor as said hub rotates, said CMOS sensor being configured to produce a corresponding signal indicative of said hub rotation.

14. The fuel level sensor of claim 13 wherein said light source comprises a light emitting diode (LED).

15. The fuel level sensor of claim 13 further including a processor electrically coupled to said CMOS sensor configured to process said signal from said CMOS sensor and produce said fuel level signal by correlating rotation of said hub with movement of said float arm.