Tool with hydraulic system for regenerative extension and two-speed operation
AssigneeMilwaukee Electric Tool Corporation
InventorJames G. Ballard
Life of this patent
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Abstract
Embodiments of the invention provide a hydraulic tool including a hydraulic actuator cylinder, a piston, a fluid reservoir, a pump, a regeneration check valve, and a pilot-operated valve. The regeneration check valve is disposed in a regenerative extension fluid path that fluidly couples a first and second chamber of the hydraulic actuator cylinder. The pilot-operated valve is disposed in a power extension fluid path that fluidly couples the second chamber to a fluid reservoir.
Claims20
A pilot-operated valve for a hydraulic tool used to operate on a work piece, the hydraulic tool including a cylinder with a first chamber separated from a second chamber by a piston, a fluid reservoir, and a pump, the pilot-operated valve comprising:
- a first port fluidly coupled to the second chamber;
- a second port fluidly coupled to the fluid reservoir;
- a pilot port fluidly coupled via a pilot line to a hydraulic supply line between the pump and the first chamber;
- a valve cavity fluidly coupled to the pilot port;
- a valve piston and valve rod positioned in the valve cavity;
- a check valve coupled to the valve rod,
- the check valve being closed in an unactuated first state when a pressure in the pilot line is below a threshold pressure value, thereby blocking a powered extension fluid path between the second chamber and the fluid reservoir in order to allow the piston to extend at a first speed as fluid fills the first chamber from the fluid reservoir;
- the check valve being open in an actuated second state when the pressure in the pilot line exceeds the threshold pressure value, thereby opening the powered extension fluid path to direct fluid from the second chamber to the fluid reservoir and allow the piston to extend at a second speed less than the first speed.
Dependencies are inferred from the claim text.