Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
1997-07-03
2001-09-04
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S658000, C073S335040, C056S01020E
Reexamination Certificate
active
06285198
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a grain moisture sensor that is particularly well adapted for use on an agricultural combine.
2. Description of the Prior Art
Precision farming uses Global Positioning Satellites (GPS) to determine the exact location of a agricultural machine in the field. The machine is fitted with a receiver for receiving radio wave signals from the positioning satellites and converting these signals into position data. Other machine mounted sensors are used to detect crop conditions, such as crop moisture and yield. By combining this information the farmer is able to generate detailed maps of field conditions. The farmer can then take these maps and better control inputs, such as seed, fertilizer and other chemicals.
In yield mapping the farmer maps the output or yield of the field. Typically an agricultural combine would be mounted to a GPS receiver and a mass flow sensor. The mass flow data is combined with the GPS data to form a yield map. Impact type mass flow sensors are sensitive to grain moisture content. Moisture content affects grain weight and this variable must be accounted for in accurately determining mass flow. U.S. Pat. No. 5,343,761 discloses a combine mounted mass flow sensor having capacitance type moisture sensor.
SUMMARY
It is one of the objects of the present invention to provide a moisture sensor having a larger measurement plate area and sample volume than traditional moisture sensors.
It is another object of the present invention to provide a moisture sensor having a very consistent grain sample for each measurement.
It is feature of the present invention that the sensor is mounted to the clean grain elevator. This mounting location reduces the time delay between grain cutting and moisture measurement.
The moisture sensor comprises a vertical chamber having an inlet and an outlet. The chamber is mounted to the clean grain elevator. The chamber is defined by a first wall adjacent and parallel to the clean grain elevator and a second wall spaced from and parallel to the first wall. The first and second walls are joined by two sidewalls. The bottom of the chamber is provided with a paddle wheel which forms a flow control means for retaining clean grain in the chamber. The paddle wheel is rotated by an electric motor. Three conductive plates are positioned between the inlet and the paddle wheel and form a capacitance moisture sensing means. The first and second plates are parallel and adjacent to the first and second walls. The first and second plates are electrically coupled to one another by a jumper. The jumper is formed from the sheet metal of the first and second plates. The third plate is located between the first and second plates. It is positioned in the middle of the chamber between the first and second plates.
The clean grain passing between the first and third, and second and third plates forms a dielectric material. The conductivity of the grain and thereby the capacitance of the sensor is directly related to the moisture content of the grain. The moisture sensor is provided with an electronic controller. The electronic controller controls the operation of the electric motor driving the paddle wheel. The electric motor ensures there is an adequate supply of grain in the chamber for moisture readings.
A photoelectric emitter and a photoelectric sensor are mounted to the chamber for detecting the supply of grain in the chamber. More specifically, the emitter and sensor are positioned near the top of the chamber and the emitter projects a beam across the chamber where it is reflected back to the sensor by a reflective surface. When the sensor does not detect the beam, grain is blocking the beam and an adequate supply of grain is present in the chamber. Therefore the motor is operated and the paddle wheel turned removing some of the grain out the bottom of the chamber. If the sensor detects the beam, the electric motor is stopped causing clean grain to back up in the chamber.
The combine maybe provided with an additional sensor which detects of the separator is being operated. For example, if the operator shuts off the separator the speed of the separator decreases and this speed drop can be detected. In such a situation the electronic controller drives the electric motor for approximately 20 seconds to evacuate grain from the chamber. In this situation the electronic controller assumes the combine is no longer processing grain and the remaining grain in the chamber is directed to the clean grain elevator and from there into the grain tank.
REFERENCES:
patent: 2665409 (1954-01-01), Rogers
patent: 2788487 (1957-04-01), Grogg
patent: 3482162 (1969-12-01), Wochnowski
patent: 3760267 (1973-09-01), Williams
patent: 4547725 (1985-10-01), Oetiker
patent: 4853614 (1989-08-01), Carver
patent: 5343761 (1994-09-01), Myers
patent: 5616851 (1997-04-01), McMahon
patent: 2087704 (1982-06-01), None
Hawk Kent Robert
Nelson Frederick William
Pickett Terence Daniel
Smith Wayne Farrior
Deb Anjan K.
Deere & Company
Metjahic Safet
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