A hydraulic system for a working machine, the system comprising: an electric machine connected to a first hydraulic machine and to a second hydraulic machine via a common axle, an output side of the second hydraulic machine being connected to an input side of the first hydraulic machine, wherein the first hydraulic machine is a variable displacement hydraulic machine with unidirectional flow; at least one hydraulic consumer hydraulically coupled to an output side of the first hydraulic machine via a supply line and configured to be powered by the first hydraulic machine; a first return line hydraulically coupling the hydraulic consumer to the input side of the first hydraulic machine.

A header is supported by a pair of hydraulic float cylinders, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration and/or velocity. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. A lift force greater than that required to lift the header can be provided by a lift cylinder and can be opposed in a controlled manner to apply a controlled downforce by the back of the same cylinder or by a separate component.

The present invention relates to an electrohydrostatic system having a hydraulic cylinder comprising a first cylinder chamber and a second cylinder chamber. Furthermore, the electrohydrostatic system has a fluid hydraulic supply device for providing a hydraulic fluid, a fluid hydraulic motor pump unit, designed to provide a fluid hydraulic volume flow in order to move the hydraulic cylinder. A motor control device is designed to provide a rated current for an electrical drive of the fluid hydraulic motor pump unit. Moreover, the electrohydrostatic system has at least one fluid hydraulic safety valve, which on a first valve side is connected to one of the cylinder chambers of the hydraulic cylinder and on a second valve side is connected to the fluid hydraulic motor pump unit. The fluid hydraulic safety valve can be bridged via a bypass connection with a fixed orifice plate, wherein the bypass connection is connected to the first valve side and to the second valve side of the at least one fluid hydraulic safety valve. Moreover, the electrohydrostatic system has a pressure sensor that is connected to one of the cylinder chambers of the hydraulic cylinder. The pressure sensor is designed to detect a fluid hydraulic pressure on one of the cylinder chambers and, according to the detected fluid hydraulic pressure, to provide an enabling signal for the motor control device to provide the rated current for the electrical drive of the fluid hydraulic motor pump unit.

The present invention is related to a construction machine, the construction machine including: a main pump; a swing motor operated by receiving a hydraulic oil from the main pump; a swing valve configured to control flow of the hydraulic oil by the main pump to supply the hydraulic oil to the swing motor and to control the flow of the hydraulic oil having been discharged from the swing motor; a hydraulic oil control valve unit provided between the swing motor and the swing valve and configured to control the flow of the hydraulic oil according to a pressure of the hydraulic oil at opposite ends; a first accumulator configured to store the hydraulic oil having passed through the hydraulic oil control valve unit when the swing motor is decelerated; a regeneration control valve provided between the hydraulic oil control valve unit and the first accumulator; and a controller configured to control the hydraulic oil control valve unit and the regeneration control valve by determining acceleration or deceleration of the swing motor.

Multi-rotor hydraulic drone (1) comprising: —a plurality of hydraulic motors (6) each receiving a pressurised fluid, —propellers (5) driven by the hydraulic motors (6), —at least one hydraulic pump (10) driven by at least one motor (11) for pressurising the fluid, —a system for supplying the hydraulic motors (6) with pressurised fluid, —a flight controller (14) for controlling the supply system according to the desired rotation speed for the hydraulic motors (6), the supply system comprising several channels (35; 36; 37; 38) for adjusting the power of at least one portion of the hydraulic motors (6).

Presented herein are systems and methods for attenuating certain pulsations in a hydraulic system comprising a pump and a hydraulic actuator. In certain aspects, an accumulator comprising an internal volume that is divided into a working chamber and a contained chamber may be utilized to at least partially attenuate propagation of certain pulsations in the system. The working chamber may be fluidically coupled to the pump via a first flow path and fluidically coupled to a chamber of the actuator via a second flow path. The system may be designed such that a first inertance of the first flow path is greater than a second inertance of the second flow path. Additionally or alternatively, the system may be designed such that a resonance associated with the first inertance and a compliance of the accumulator may occur at a resonance frequency of less than 90 Hz.

A time delay valve includes a switching valve that switches between a first position and a second position; an urging member that urges the switching valve toward the first position; a driving mechanism that urges the switching valve toward the second position located opposite the first position in the presence of the pressure of a pilot fluid being supplied: a pilot flow channel that introduces the pilot fluid to the driving mechanism; and a delaying mechanism that delays the switching timing of the switching valve. The delaying mechanism includes a first throttle valve provided on the pilot flow channel, a compensation mechanism that urges the switching valve toward the first position in the presence of the pressure of the pilot fluid being supplied, and a compensation flow channel that is branched from the pilot flow channel to introduce a portion of the pilot fluid to the compensation mechanism.

The invention relates to a compressed-air supply system for operating a pneumatic installation in a pneumatic system of a vehicle, comprising: a compressed-air feed; a compressed-air connection point to the pneumatic installation; a venting connection point to the environment; a pneumatic main line between the compressed-air feed and the compressed-air connection point, which pneumatic main line has an air dryer; a venting valve, which is arranged on the pneumatic main line and is designed as a pilot valve and has a pilot connection point; a compressor having at least one compressor stage; and, in addition to the pneumatic main line, a pilot valve and a pneumatic pilot channel that connects the pilot valve to the pilot connection point of the venting valve. With respect to the compressed-air supply system, according to the invention, a pressure-holding pneumatic reservoir device is connected to the pilot connection point, which reservoir device is designed to provide a control pressure for the pilot connection point, in particular independently of a pressure in the pneumatic main line during venting of the pneumatic system, and the pressure-holding pneumatic reservoir device has at least one separate pilot pressure accumulator, which can be pneumatically connected to the pilot connection point via the control line.

A hydrostatic cylinder with a gas pressure accumulator, which is preferably designed as a piston accumulator, and which is arranged concentrically on the outer circumference of the cylinder is disclosed. A gas pressure is produced via a constant pressure source and is limited or is essentially constant in the gas pressure accumulator and also a constant pressure medium pressure is independent of the degree of filling of the gas pressure accumulator.

This disclosure relates to a hydraulic system for a hydro-mechanical machine comprising a rotary mechanism and a boom cylinder The hydraulic system includes a primary accumulator configured to receive and store high-pressure fluid in response to starting and stopping of the rotary mechanism. A control system configured to enable passage of the high-pressure fluid stored in the primary accumulator to a rotary control valve configured to control the rotary mechanism, and a boom control valve configured to control the boom cylinder through the hydraulic supply circuit, based on a predefined pressure threshold associated with the primary accumulator. A secondary accumulator coupled to the primary accumulator and the control system via the hydraulic supply circuit is configured to store surplus high-pressure fluid provided by the primary accumulator through the hydraulic supply circuit.