초록 ▼

A closed-loop height control for the header of a combine harvester permits adjustment of height setpoint and deadband from the operator\s platform without stopping the combine. A variable capacitance is rotated in accordance with minimum clearance between header and ground to generate a continuous e

A closed-loop height control for the header of a combine harvester permits adjustment of height setpoint and deadband from the operator\s platform without stopping the combine. A variable capacitance is rotated in accordance with minimum clearance between header and ground to generate a continuous electrical header height signal which is compared to a setpoint signal indicative of desired header height to derive a height error signal whose value is at a null level when actual header height is equal to desired height indicated by the setpoint signal and which deviates in both magnitude and direction from the null level as a function of the variation between actual header height and setpoint height. Raise and lower command signals are derived in response to a predetermined deviation of the height error signal in opposite directions respectively from the null level by first and second Schmitt trigger circuits having switching levels which respectively are greater than and less than the null value. A logic circuit controls transmittal of the raise and lower command signals to electrohydraulic power means for raising and lowering the header, and the operator need only actuate a single raise-lower switch at the operator\s platform to select whether the logic circuit is in an automatic mode in which the command signals are transmitted or a standby mode in which they are blocked from the power means.

대표청구항 ▼

A closed loop header height control for a crop harvester having a vertically adjustable cut crop receiving header comprising, in combination, position sensor means for deriving an electrical header height signal which continuously is an analog of the minimum clearance between said header and ground,

A closed loop header height control for a crop harvester having a vertically adjustable cut crop receiving header comprising, in combination, position sensor means for deriving an electrical header height signal which continuously is an analog of the minimum clearance between said header and ground, setpoint adjusting means for deriving a selectively variable electrical setpoint signal indicative of desired height of said header, means for comparing said header height signal to said setpoint signal and for deriving a height error signal whose value is null when actual header height equals said desired height indicated by said setpoint signal and which deviates in magnitude and direction from said null as a function of the deviation between said actual header height and said desired height, deadband establishing means for deriving electrical raise and lower command signals in response to a predetermined deviation in the magnitude of said height error signal in opposite directions respectively from said null, and power means responsive to said raise and lower command signals respectively for raising and lowering said header.