US 4,164,167 AGranted

Hydraulic servomechanism

AssigneeIshikawajima-Harima Jukogyo Kabushiki Kaisha

InventorsIsao Imai, Mitsuru Muto

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Abstract

Disclosed is a hydraulic servomechanism including a control loop consisting of an input device, an adder-amplifier, a servovalve, a cylinder or actuator and a load operatively connected in the order named for controlling the position of the load, a position feedback loop and an acceleration feedback loop. In one embodiment of the invention, the hydraulic servomechanism further includes a feedback loop wherein an output from an accelerometer or pressure sensor for detecting a differential pressure across a piston in the cylinder and an error signal from the adder-amplifier are arithmetically processed and fed back to the adder-amplifier. In another embodiment, the hydraulic servomechanism further includes an additional feedback loop wherein an output from a two-input adder to which are applied a signal representative of a supply pressure of working oil to be delivered from the servovalve to the cylinder and a signal representative of a pressure difference across a piston of the cylinder is arithmetically processed and fed back to a divider inserted between the adder-amplifier and the servovalve. In both embodiments, shocks are substantially eliminated in a hydraulic system.

Claims3

Dependent claims

A hydraulic servomechanism wherein an input device, an adder-amplifier, a divider, a servovalve, a piston within a cylinder and a load are operatively coupled in the order named;

a position sensor for detecting a displacement of said load operatively connected to said adder-amplifier;
means for detecting an acceleration of said piston operatively connected to said adder-amplifier, an adder, a supply pressure setting device having its output terminal connected to one of two input terminals of said adder, a pressure sensor with two output terminals for detecting a pressure difference across said piston in said cylinder having one of said two output terminals connected directly to one of two stationary contacts of a switching means and the other output terminals connected to the other stationary contact through an inverter, a movable contact of said switching means being connected to the other input terminal of said adder, the output of the adder being connected through a function generator to said divider, an output terminal of said divider being connected to said switching means through a sign discriminator so that in response to an output signal from said sign discriminator said movable contact of said switching means closes either of said two stationary contacts thereof.

Dependencies are inferred from the claim text.