SOIL HARDNESS DETECTOR OF PADDY FIELD MOBILE AGRICULTRAL MACHINE

摘要

PURPOSE:To detect the soil hardness accurately and safely by providing a sound wave oscillator and a sound wave receiver to measure the speed or the time of sound wave propagation. CONSTITUTION:When a switch signal is received from a switch signal circuit 16, the sound wave is oscillated from an oscillator 3 into soil, and a time measuring circuit 15 measures the time to the reception of a receiver 4. This time is compared with the reference time of a reference time setting circuit 17 to generate a control signal from a control signal circuit 18. If the arrival time of the sound wave is shorter than the reference time, the switching sensitivity of an oil pressure valve due to a float is not changed. If the soil hardness is lower, the arrival time of the receiver 4 is shorter because the sound wave is propagated in the soil in lower speed, and an adjustment control circuit 14 performs the control to make the sensitivity of the oil pressure valve higher. If the soil hardness is higher, the circuit 14 performs the control to make the sensitivity of the oil pressure valve lower because the propagation speed of the sound wave is lower.