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US 4,741,364 AGranted
Pilot-operated valve with load pressure feedback
AssigneeDeere & Company
InventorsKenneth J. Stoss, Richard A. Felland
Life of this patent
Estimating the term…
Abstract
A pilot-operated electrohydraulic valve has a pilot valve member exposed to load pressure via a load pressure feedback passage. Part of the pilot valve member forms a feedback valve which closes communication through the feedback passage upon a predetermined movement of the pilot valve so that the pilot valve can be fully opened without having to overcome the load pressure which would otherwise act on the pilot valve.
Claims13
A valve comprising:
- a housing having a valve bore therein, and having a supply port communicating the valve bore with a pressure source, a return port communicating the valve bore with a reservoir and a load port communicating the valve bore with a hydraulic load;
- a pressure-operated main valve member movable in the valve bore to control fluid communication between the load port and the supply and return ports;
- a pressure-responsive pilot valve member movable to control a pilot pressure communicated to the main valve member;
- a load feedback passage communicating fluid pressure from the load port to the pilot valve;
- and
- feedback valve means for opening and closing fluid communication through the load feedback passage.
3 more elements
A valve comprising:
- a housing defining a valve bore therein, a supply port communicating the valve bore with a pressure source, a return port communicating the valve bore with a fluid reservoir, and a load port communicating the bore with a load;
- a main valve member received in the valve bore, the main valve member and the housing cooperating to define a pilot chamber, the main valve member being movable in response to changes in fluid pressure in the pilot chamber to control fluid communication between the load, return and supply ports;
- a pilot supply passage communicating the supply port with the pilot chamber;
- a pilot return passage communicating the return port with the pilot chamber;
- a pilot valve member movable in the housing to control fluid communication between the pilot chamber and the return pilot passage, the pilot valve member and the housing cooperating to define a feedback chamber, fluid pressure in the feedback chamber urging the pilot valve member in a direction closing communication between the pilot chamber and the return pilot passage;
- a feedback passage communicating the load port with the feedback chamber;
- and
- feedback valve means for controlling fluid communication through the feedback passage.
5 more elements
A valve comprising:
- a housing having a valve bore therein, and having a supply port communicating the valve bore with a pressure source, a return port communicating the valve bore with a reservoir and a load port communicating the valve bore with a hydraulic load;
- a pressure-operated main valve member movable in the valve bore to control fluid communication between the load port and the supply and return ports;
- a pilot valve movable to control a pilot pressure communicated to the main valve member;
- means for sensing fluid pressure in the load port and for influencing movement of the pilot valve as a function of the sensed load port pressure so as to compensate for changes in fluid viscosity and pressure of the pressure source;
- and
- means for cancelling the effect of the feedback means when the pilot valve is moved to cause the main valve member to maximize pressure at the load port.
3 more elements
Dependencies are inferred from the claim text.