US 11,678,597 B2
Negative downforce system for ground engaging machinery
David C. Schulte, Naperville, IL (US)
Assigned to Parker-Hannifin Corporation, Cleveland, OH (US)
Filed by Parker-Hannifin Corporation, Cleveland, OH (US)
Filed on Feb. 14, 2022, as Appl. No. 17/670,732.
Application 17/670,732 is a continuation of application No. 16/545,324, filed on Aug. 20, 2019, granted, now 11,246,254.
Claims priority of provisional application 62/721,132, filed on Aug. 22, 2018.
Prior Publication US 2022/0159896 A1, May 26, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. F15B 9/03 (2006.01); A01B 63/114 (2006.01); A01B 63/00 (2006.01); F15B 11/028 (2006.01)
CPC A01B 63/114 (2013.01) [A01B 63/008 (2013.01); F15B 9/03 (2013.01); F15B 11/028 (2013.01); F15B 2211/526 (2013.01); F15B 2211/7053 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A downforce control system for an agricultural ground engaging unit, comprising:
a pressure source;
a double acting cylinder having a first chamber and a second chamber, wherein pressure in the first chamber provides a down force and that pressure in the second chamber provides an up force acting against the down force of the first chamber, the double acting cylinder providing a downward force to the agricultural ground engaging unit;
a fixed pressure control valve positioned between the pressure source and the first chamber of the double acting cylinder, the fixed pressure control valve configured to maintain a fixed pressure in the first chamber of the double acting cylinder;
a proportional pressure control valve positioned between the pressure source and the second chamber of the double acting cylinder;
a force feedback sensor mounted on the agricultural ground engaging unit to sense a downward force of the agricultural ground engaging unit;
a controller configured to compare the downward force of the agricultural ground engaging unit sensed by the force feedback sensor to a predetermined downward force requirement of the agricultural ground engaging unit, the controller adapted to control the proportional pressure control valve to increase or reduce the downward force to the agricultural ground engaging unit only by increasing or decreasing the pressure in the second chamber of the double acting cylinder.