Patent ID: 11958177
Assignee: MILWAUKEE ELECTRIC TOOL CORPORATION
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC B  F  H | IPC B  F  H

Claim 4:
5. A hydraulic pump, comprising:
a work port configured to couple to a fluid supply line of a hydraulic tool;
a high-flow piston configured to supply fluid along a first flow path to the work port;
a plurality of high-pressure pistons configured to supply the fluid along a second flow path to the work port;
an unloading valve fluidly coupled to the first flow path and the second flow path, wherein the unloading valve is actuatable between an open state and a closed state, wherein the unloading valve is configured to permit the fluid to flow from the high-flow piston to the work port in the open state, wherein the unloading valve is configured to inhibit the fluid from flowing from the high-flow piston to the work port in the closed state, wherein the unloading valve is configured to actuate from the open state to the closed state when a pressure level of the fluid in the second flow path exceeds a first threshold pressure;
a pressure transducer configured to sense a pressure level of the fluid supplied to the work port and generate a signal indicative of the sensed pressure level being greater than a second threshold pressure;
a shear seal valve configured to, responsive to the signal from the pressure transducer indicating that the sensed pressure level is greater than the second threshold pressure, fluidly couple the second flow path to a hydraulic fluid tank,
wherein the second threshold pressure is related to an end of an operation of the hydraulic tool; and
a dump valve having a movable element including (i) a first surface configured to be subjected to the fluid in the second flow path, and (ii) a second surface configured to be subjected to the fluid in a return flow path between the work port and the dump valve,
wherein the movable element is configured to move from a first position to a second position responsive to a fluid pressure differential between the fluid at the second surface and the fluid at the first surface being greater than a threshold pressure differential,
wherein, when the movable element is in the first position, the dump valve is configured to fluidly decouple the return flow path from the hydraulic fluid tank, and
wherein, when the movable element is in the second position, the dump valve is configured to fluidly couple the return flow path to the hydraulic fluid tank.