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US 6,966,240 B2Granted
Hydraulic ratchet wrench with double-action hydraulic cylinder piston drive
OwnerAlexander Kipfelsbergerinventor
Life of this patent
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Abstract
The invention relates to a hydraulic ratchet wrench with a double-action hydraulic cylinder piston drive with a gear pump (20) and a piston pump (21). According to the invention, a working stroke and a return stroke are controlled through a reversal of rotational direction of a pump motor (4), whereby the necessary flow volume is produced automatically via internal flow control valves, and without additional valve controls.
Claims17
A hydraulic circuit including:
- a hydraulic ratchet wrench having a double-action hydraulic cylinder with a piston that is displaceable in the hydraulic cylinder, a piston rod actuating said ratchet, a working stroke chamber in the hydraulic cylinder having a high-pressure chamber on one piston side and a low-pressure return stroke chamber on the other piston side with the piston rod, a hydraulic pump arrangement with a gear pump and a piston pump connected via hydraulic controls to the working stroke chamber and the return stroke chamber to drive said wrench in alternating work strokes and return strokes, wherein said circuit comprises:
- a gear pump connected to said working stroke chamber by a working stroke oil line and connected by a return stroke oil line to said return stroke chamber;
- said working stroke oil line connected to an oil reservoir by a first suction port;
- said return stroke oil line connected to said oil reservoir by a second suction port;
- an oil backflow line connected to said working stroke oil line and said oil reservoir, and a blocking valve arranged in said backflow line to selectively deliver an oil flow from said working stroke oil line;
- said piston pump connected to said oil reservoir by a piston pump suction line and to said working stroke chamber by said working stroke oil line;
- a pump control actuating said gear pump in one direction of rotation for delivering oil through said working stroke oil line to said working stroke chamber, and actuating said gear pump in an opposite direction for delivering oil through said return stroke oil line to said return chamber;
- a working stroke flow valve arrangement in communication with said working stroke oil line to direct a flow of working oil to said work stroke chamber during said work stroke;
- a return stroke flow valve arrangement in communication with said return working stroke oil line and said oil backflow line to direct a flow of oil back to said oil reservoir during said return stroke;
- and
- said working stroke and return stroke valve arrangements operating automatically in response to flow conditions in one or more of said working stroke oil line, return stroke oil line, and backflow oil line caused by operating said gear pump in opposite directions.
8 more elements
A hydraulic circuit including:
- a hydraulic ratchet wrench having a double-action hydraulic cylinder, a displaceable piston located in said hydraulic cylinder, a piston rod actuating said ratchet, a working stroke chamber located in said hydraulic cylinder with a high-pressure chamber on one piston side and a low-pressure return stroke chamber on the other piston side with said piston rod, a hydraulic pump arrangement including a gear pump and a piston pump, connected via hydraulic controls to the working stroke chamber and the return stroke chamber, said gear pump and said piston pump being driven by means of a pump motor controlled by pump motor controls through its drive shaft, whereby the gear pump pumps a relatively large quantity of hydraulic oil per motor revolution and the piston pump pumps a relatively smaller amount per motor revolution, wherein said hydraulic circuit comprises:
- a first gear pump connection connected to a working stroke oil line and a working stroke chamber;
- a second gear pump connection connected to a return stroke oil line and to a return stroke chamber;
- said working stroke oil line being connected to an oil tank by a first connection point via a first suction port and a first suction check valve;
- said return stroke oil line being connected at a second connection point to said oil tank via a second suction port and a second suction check valve;
- said working stroke oil line having a high pressure check valve with a blocking action in the direction of said first connection point between said first connection point and said working stroke chamber;
- said piston pump being connected to said oil tank via a piston pump suction line having a piston pump delivering outlet connected to said working stroke oil line;
- a hydraulic oil flowback line communicating with said oil tank;
- said flowback oil line connected via a low pressure limit valve to said working stroke oil line whereby a flowback is delivered by the low pressure limit valve when a predetermined low pressure has been reached;
- said flowback oil line being connected via an unblocking check valve controlled as a function of pressure in said return stroke oil line to said working stroke oil line, said unblocking check valve normally blocking flow to said flowback line;
- and
- a pump motor actuated for a working stroke in one direction of rotation to pump oil through said delivery outlet of said gear pump, said pump motor actuated for a return stroke to rotate in the opposite direction, to pump oil through said suction inlet of said gear pump, and said radial piston pump pumping oil in the same direction with both directions of rotation.
9 more elements
Dependencies are inferred from the claim text.