Abstract: The invention proposes a novel drive with electrical power control for machines which have to execute cyclic movements with high accelerations. An electric motor drives a pump which, in turn, is connected directly to a cylinder. This arrangement has added to it a system of pressure accumulators and valves which give the system the property of an oscillator. The acceleration forces in the event of a cyclic movement near to resonance are then exerted largely by the pressure accumulators and the cylinders connected to these. This leads to a relieving of the electric motor and makes it possible to install lower powers on the machine or else, for the same power, achieve shorter cycle times of the machine.

Abstract: The invention proposes a novel drive with electrical power control for machines which have to execute cyclic movements with high accelerations. An electric motor drives a pump which, in turn, is connected directly to a cylinder. This arrangement has added to it a system of pressure accumulators and valves which give the system the property of an oscillator. The acceleration forces in the event of a cyclic movement near to resonance are then exerted largely by the pressure accumulators and the cylinders connected to these. This leads to a relieving of the electric motor and makes it possible to install lower powers on the machine or else, for the same power, achieve shorter cycle times of the machine.

Abstract: A system that includes a pump driven by a variable speed electric motor, the pump being directly connected to a hydraulic actuator by an open hydraulic circuit. This setup allows using one motor pump combination to drive any number of axes sequentially. The main advantages are significant energy savings but also higher control quality achieved by the substitution of control valves. Power control is dedicated to electronic power transistors while hydraulics are used for power transmission. For two and four quadrant operation, a hydraulic accumulator is proposed exerting a spring load on the hydraulic actuator. This allows for driving and braking the actuator and the associated machine axis in both directions of motion while the hydraulic pressure is always applied to the same port of the pump. The other pump port can be connected to tank.