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Closed circuit energy recovery system for a work implement
 
   
Document Number
US Patent 7325398
Issued Date
February 5, 2008
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Abstract
A closed circuit hydraulic system includes a fluid reservoir, a hydraulic cylinder having a cylinder rod, a bidirectional variable displacement hydraulic pump that pumps fluid to either extend or retract the cylinder rod on demand, a flow control valve for relieving pressure between the variable displacement hydraulic pump and the cylinder, and a low pressure check valve between the variable displacement hydraulic pump and the fluid reservoir. Also included is a charge pump for charging the variable displacement hydraulic pump and an accumulator for saving extra energy and fluid from the hydraulic cylinder during the retraction of an extended cylinder rod and using that fluid and energy during the extension of the hydraulic cylinder to reduce a load on the charge pump. The flow control valve opens on demand to allow floating. The low pressure check valve opens when pressure at an inlet of the variable displacement hydraulic pump is low to provide additional fluid and pressure so as to avoid cavitation. A method for using the closed circuit hydraulic system is also provided.
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Number of Claims:
16
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Owner
Deere & Company (Moline, IL)
Published
February 5, 2008
Application Number
10/794,965
Filed
March 5, 2004
US Classification
60/476   60/414
Int'l Classification
F16D   31/02   (20060101)  
Examiner
USPTO Field of Search
60/414   60/475   60/476  
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