Engine control system responsive to optical fuel composition sensor

• US 4,974,552 A
• Filed: 01/09/1990
• Issued: 12/04/1990
• Est. Priority Date: 01/09/1990
• Status: Expired due to Fees

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Sickafus, Edward N.
• Primary Examiner(s): Argenbright, Tony M.
• Application Number:
  US07/462,187
• Time in Patent Office: 329 Days
• Field of Search: 123/1 A, 123/478, 123/494, 123/575, 73/61.1 R, 250/343, 250/574
• US Class Current: 123/1.00A
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02M 43/00 Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
• CPC Class Codes: G01N 21/43 by measuring critical angle
• CPC Class Codes: Y10S 250/903 with prism contacting liquid

Abstract

An engine control system for operating an internal combustion engine with any mixture of alcohol and gasoline. The control system includes an air/fuel ratio control system providing a desired fuel charge in relation to the alcohol and gasoline content of the fuel which is indicated by an optical sensor. In one embodiment, the optical sensor includes a hemispherical lens having hemispherical recesses formed through the lens base equidistant from the lens plane of symmetry. A light emitting diode positioned in one recess irradiates substantially the entire 2 π steradian outer surface of the hemispherical lens. A portion of the transmitted light is reflected from substantially the entire hemispherical lens and substantially focused on a photodetector positioned in the other recess. Emitter and detector are substantially positioned at conjugate focii of the lens which provides substantially a 2 π steradian collection aperture. The amount of transmitted light reflected is related to the index of refraction of the surrounding fuel mixture thereby providing a measurement of fuel composition.

Claims

1. An optical sensor for determining the ratio for each of two constituents in a fluid mixture wherein each constituent has a different index of refraction, comprising:

a hemispherical lens portion having an axis, a hemispherical surface surrounded by the fluid mixture, and a base;

a light emitting source aligned with said axis and positioned adjacent to said base for transmitting light against substantially all of said hemispherical surface; and

a light detector aligned with said axis and positioned on said base adjacent said light emitting source, said light detector collecting light which is reflected from substantially all of said hemispherical surface such that the optical sensor has an effective aperture of nearly 2 π

steradians, said light detector providing an electrical signal related to the proportion of the constituents in the fluid mixture.

2. The optical sensor recited in claim 1 wherein a ratio of said reflected light to said transmitted light is related to a ratio of refractive indices of the mixture constituents.

3. The optical sensor recited in claim 1 wherein the mixture constituents comprise alcohol and gasoline.

4. The optical sensor recited in claim 1 wherein said light emitting source comprises a light emitting diode.

5. The optical sensor recited in claim 1 wherein said light detector comprises a photodetector and said light emitting source comprises a light emitting diode, the optical sensor further comprising feedback means responsive to light reflected by said hemispherical lens for regulating electrical power supplied to said light emitting diode such that its emitted light remains substantially constant.

6. An optical sensor for determining the proportion of each of two constituents in a fluid mixture wherein each constituent has a different index of refraction, comprising:

a hemispherical lens portion having an axis, a hemispherical surface surrounded by the fluid mixture, and a base with an axially aligned recess formed in said base;

a light emitting source positioned in said recess which irradiates substantially all of said hemispherical surface; and

a light detector positioned adjacent said base directly below said light emitting source and aligned with said axis, said light detector collecting light which is emitted from said light source and reflected from substantially all of said hemispherical surface such that the optical sensor has an effective aperture of nearly 2 π

steradians, said light detector providing an electrical signal related to the proportion of constituents in the fluid mixture.

7. The optical sensor recited in claim 6 wherein said recess in said bottom surface includes a hemispherical portion and wherein said light source irradiates said hemispherical portion such that substantially all of said emitted light is transmitted through said hemispherical portion.

8. The optical sensor recited in claim 6 wherein a ratio of said reflected light to said emitted light is related to a ratio of refractive indices of the mixture constituents.

9. The optical lens recited in claim 6 wherein the mixture constituents comprise alcohol and gasoline.

10. An optical sensor for determining constituents of a fluid mixture wherein each constituent has a different index of refraction, comprising:

a hemispherical lens having its hemispherical surface surrounded by said fluid mixture and also having a base, said hemispherical lens having a plane of symmetry symmetrical about a center axis of said hemispherical lens;

a light emitting source positioned in a recess within said base which is offset a predetermined distance from said plane of symmetry, said light source irradiating substantially all of said hemispherical surface; and

a light detector positioned substantially at a conjugate focus to said light emitting source which is opposite said plane of symmetry with respect to said light emitting source by a distance substantially equal to said predetermined distance, said light detector collecting light which is transmitted from said light source and reflected from substantially all of said hemispherical surface such that the optical sensor has an effective aperture of nearly 2 π

steradians, said light detector providing an electrical indication of the constituents in the fluid mixture.

11. The optical lens recited in claim 10 wherein said recess in said bottom surface includes a hemispherical portion and wherein said light source irradiates said hemispherical portion such that substantially all of said transmitted light is transmitted through said hemispherical portion.

12. The optical lens recited in claim 10 wherein said conjugate focal point is located on an opposite side of said plane of symmetry with respect to said light emitting source and below said light emitting source.

13. The optical lens recited in claim 10 wherein said light detector is positioned on said base.

14. The optical lens recited in claim 10 wherein a ratio of said reflected light to said transmitted light is related to a ratio of refractive indices of the mixture constituents.

15. A control system for an internal combustion engine which operates with a fuel mixture composed substantially of two constituents each having a different index of refraction, said control system comprising:

a hemispherical lens having an axis, a hemispherical surface surrounded by the fluid mixture, and a base with an axially aligned recess formed in said base;

a light emitting source positioned in said recess which irradiates substantially all of said hemispherical surface;

a light detector positioned adjacent said base directly below said light emitting source and aligned with said axis, said light detector collecting light which is transmitted from said light source and reflected from substantially all of said hemispherical surface such that the optical sensor has an effective aperture of nearly 2 π

steradians; and

control means responsive to said light detector for adjusting an engine operating parameter as a function of constituent composition of the fuel mixture.

16. The control system recited in claim 15 wherein said control means regulates engine air/fuel ratio in relation to the constituent composition of the fuel mixture.

17. The control system recited in claim 15 wherein said control means regulates engine ignition timing in relation to the constituent composition of the fuel mixture.

18. A control system for an internal combustion engine which inducts a mixture of air and a fuel mixture composed of two constituents wherein each constituent has a different index of refraction, said control system comprising:

a hemispherical lens having its hemispherical surface surrounded by said fluid mixture and also having a base, said hemispherical lens having a plane of symmetry symmetrical about a center axis of said hemispherical lens;

a light emitting source positioned in a recess within said base which is offset a predetermined distance from said plane of symmetry, said light source irradiating substantially all of said hemispherical surface;

a light detector positioned substantially at a conjugate focal point to said light emitting source which is opposite said plane of symmetry with respect to said light emitting source by a distance substantially equal to said predetermined distance, said light detector collecting light which is transmitted from said light source and reflected from substantially all of said hemispherical surface such that the optical sensor has an effective aperture of nearly 2 π

steradians, said light detector providing an indication of the constituents in the fluid mixture;

reference means responsive to said light detector for providing an air/fuel ratio reference as a function of constituent composition of the fuel mixture;

airflow means for calculating airflow inducted into the engine; and

air/fuel ratio means for delivering fuel into the engine in response to said inducted airflow calculation and said air/fuel ratio reference such that the engine operates at said air/fuel ratio reference.

19. The optical sensor recited in claim 18 wherein said light detector comprises a photodetector and said light emitting source comprises a light emitting diode, said optical sensor further comprising feedback means responsive to light reflected by said hemispherical lens for regulating electrical power supplied to said light emitting diode such that its emitted light remains substantially constant.