Automatic Feed-Rate Control for Hydrostatic-Drive Combine of Head Feeding Type (I)

Abstract

(1) An automatic feed-rate control designed for the hydrostatic-driven combine of head feeding type was tested. This automatic control system consisted of a two inputs system for feed rate sensing with a straw layer detector and a threshing torque sensor coupled with spring-mounted idlers, electric AND and OR switching circuits system with micro-switches and the feedback control system to the travelling speed (Fig, 1).
(2) The electric switching circuit for speed increase was connected in series and that of speed decrease in parallel. The feed rate of combine was controlled to increase the speed, when both the straw layer and the threshing torque were under the lower limits; and to decrease the speed, when either of them was over the upper limits. The manual control of speed was done with the main switch.
(3) In tests using only the straw layer sensing, control was good enough to keep the feed rate and the loads of combine elements constant, but was not so effective to prevent overloading of the threshing elements.
(4) In tests using only the threshing torque sensing, control was not good due to the dead time in the conveyer which feeds the material to the threshing elements and the Coulomb friction of the sensing device.
(5) When two inputs were used many tests were not successful due to the difficulty to get correct setting of the micro-switches.