Abstract A stone trap door, in the path of feed of crop material, in a combine harvester is held in a closed position by a latch control by a solenoid. The solenoid is energized to open the stone trap door by an electronic rock detection circuit. The rock detection circuit includes a piezolectric ceramic disc attached to the bottom of the table to detect vibrations induced in the bottom of the table by material conveyed along the bottom of the table toward the trap door. The piezolectric ceramic disc produces an output signal which varies in frequency and amplitude depending upon the frequency and amplitude of the vibrations induced in the bottom of the table. The output signal passes through a band pass amplifier and a peak detector which filter out all the output signals except those produced by rocks or other hard objects. The signal produced by rocks or other hard objects is then amplified to energize the solenoid and open the stone trap door.
A rock trap for a combine harvester thresher characterized by a door in the path of feed of crop material, an electronic detection device capable of detecting the presence of rocks mixed with the crop material, and a latch capable of opening the door in response to a signal from the electronic rock detection circuit indicating the presence of one or more rocks mixed with crop material.
Claim 2
Dependent Claim
67 words
A rock trap for a combine harvester thresher characterized by a door in the path of feed of crop material, an electronic detection device capable of detecting the presence of rocks mixed with the crop material, and a latch capable of opening the door in response to a signal from the electronic rock detection circuit indicating the presence of one or more rocks mixed with crop material.
Claim 3
Dependent Claim
23 words
The rock trap of claim 1 characterized by said electronic rock detection device including a piezoelectric ceramic disc attached to the table bottom.
Claim 4
Dependent Claim
24 words
The rock trap of claim 2 characterized by the door extending across the bottom of the lower end of the elevator to the cylinder.
Claim 5
Dependent Claim
26 words
The rock trap of claim 2 characterized by the electronic rock detection device including a band pass amplifier, a peak detector, and a solenoid door release.