MULTIPLE FREQUENCY GRAIN MOISTURE SENSOR FOR COMBINES

• US 20050225334A1
• Filed: 06/06/2005
• Published: 10/13/2005
• Est. Priority Date: 10/25/2001
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Kozicki, Andrzej, Phelan, James J., Funk, Robert C., Slavens, Zachary W., Rains, Gerald E.
• Granted Patent: US 6,982,562 B2
• Time in Patent Office: Days
• US Class Current: 324/694
• CPC Class Codes: A01D 41/1208 Tanks for grain or chaff for threshing machines A01F12/60
• CPC Class Codes: A01D 41/1277 for measuring grain quality
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 33/02 Food
• CPC Class Codes: G01N 33/10 Starch-containing substances, e.g. dough

Abstract

A grain moisture sensor is disclosed having a sensor cell that includes a driven plate, a sense plate proximate to and substantially parallel with the driven plate for capacitive measurement across a spacing between the driven plate and the sense plate, and a fill plate adjacent the sense plate and substantially parallel with the driven plate for sensing whether the spacing is filled with grain. Optionally, the sensor cell includes a guard proximate to the parallel to the sense plate such that the sense plate is between the driven plate and the guard. The grain moisture sensor provides for measuring real and imaginary components of an excitation voltage applied to the driven plate, measuring real and imaginary components of a sense current sensed at the sense plate, calculating a complex admittance of the cell, calculating a complex admittance of a reference admittance, and calculating a grain complex permittivity.

Claims

1-21. -21. (canceled)

22. A grain moisture sensing system comprising:

an excitation signal source for producing an excitation signal;

a sensor cell having a driven plate for applying the excitation signal and a sense plate proximate to and substantially parallel with the driven plate for capacitive measurement across a spacing between the driven plate and the sense plate such that a sense current is produced at the sense plate;

the excitation signal source electrically connected to the driven plate of the sensor cell;

a first synchronous detector adapted for measuring components of the excitation signal, the synchronous detector electrically connected to the excitation source; and

a second synchronous detector adapted for measuring components of the sense current, the second synchronous detector operatively connected to the sense plate.

23. The grain moisture system of claim 22 wherein the first synchronous detector is adapted for alternatively measuring imaginary components of the excitation signal and real components of the excitation signal.

24. The grain moisture system of claim 22 wherein the second synchronous detector is adapted for alternatively measuring imaginary components of the sense current and real components of the sense current.

25. The grain moisture system of claim 22 wherein the first synchronous detector is a mixer and the second synchronous detector is a mixer.

26. The grain moisture sensor of claim 22 wherein the excitation signal source is a switch adapted for alternatively selecting one of a first frequency in-phase signal, a first frequency quadrature signal, a second frequency in-phase signal, and a second frequency quadrature signal.