Pressure sensing regenerative hydraulic system

摘要

A regenerative hydraulic system includes a control circuit having a pressure sensing valve therein. The valve is in fluid communication with a pump and a work cylinder causing the cylinder to be actuated at a relatively high velocity during a first increment of displacement by employing regenerative techniques which interconnect the head and rod sides of the cylinder. Pressure increases due to encountering a load are monitored, and at a predetermined value, the system switches to a non-regenerative mode in which the effective force exerted by the cylinder is substantially increased. Upon switching to the non-regenerative mode, the system is latched and will remain so until the system fluid pressure drops to a second predetermined value which is substantially smaller than the first pressure, resulting in a hysteretic control characteristic which will prevent an unstable condition. A dual rate spring is included within the valve urging it into the regenerative position. The disclosed hydraulic system can be employed in tree harvesters and virtually any other type of hydraulic system including a work cylinder or its equivalent.