Closed-loop combine header height control
US4136508A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 7, 1977 |
| Grant date | Jan 30, 1979 |
| Priority date | — |
| Expiry date | Jan 7, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S56/15
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
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 r…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.