The invention concerns a device for the direct recovery of hydraulic energy in a machine, comprising at least one single-acting storage cylinder-piston device with a storage cylinder, a storage cylinder-piston and a storage cylinder chamber, with at least one differential cylinder-piston device with a differential cylinder comprising a separate rod side and base side, and with at least one hydraulic accumulator, which may be connected to the storage cylinder-piston device and/or the differential cylinder-piston device, wherein the potential energy of the storage cylinder-piston device, which retracts under a compressive load, may be at least partially stored in the hydraulic accumulator.

Method for controlling and damping the motion of a hydraulic actuator in an electro hydrostatic actuator (EHA) system comprising an electric motor, a hydraulic pump and a hydraulic fluid circuit connecting the hydraulic pump and the hydraulic actuator includes comprising: energising the electric motor to drive the hydraulic pump to supply hydraulic fluid to the hydraulic actuator through the hydraulic fluid circuit in an active mode of operation; providing a flow path between the hydraulic actuator and the hydraulic pump in a damping mode of operation such that hydraulic fluid can flow via the flow path through the hydraulic pump when the hydraulic actuator is driven by an external force; and determining a desired amount of damping to be applied to the hydraulic actuator in the damping mode of operation and providing the electric motor with one or more energy consuming means configured to provide the desired amount of damping.

A hydraulic valve arrangement (1) is provided comprising comprising a supply port arrangement having a high pressure port (2) and a low pressure port (4), a working port arrangement having two working ports (6, 7), a first valve (13) arranged between said high pressure port (2) and said working port arrangement (6, 7), a second valve (14) arranged between said low pressure port (4) and said working port arrangement (6, 7), a controller (19) for controlling said first valve (13) and said second valve (14), said controller (19) having an input connection (20) for receiving a signal of an operator input device, and a regenerative flow path which can be established by means of at least one of said first valve (13) and said second valve (14). The function of such a hydraulic valve arrangement should be enhanced. To this end said controller (19) said controller interrupts said regenerative flow path when a feed pressure at said working port arrangement (6, 7) exceeds a predetermined pressure level.

A hydraulic valve arrangement (1) is provided comprising comprising a supply port arrangement having a high pressure port (2) and a low pressure port (4), a working port arrangement having two working ports (6, 7), a first valve (13) arranged between said high pressure port (2) and said working port arrangement (6, 7), a second valve (14) arranged between said low pressure port (4) and said working port arrangement (6, 7), a controller (19) for controlling said first valve (13) and said second valve (14), said controller (19) having an input connection (20) for receiving a signal of an operator input device, and a regenerative flow path which can be established by means of at least one of said first valve (13) and said second valve (14). The function of such a hydraulic valve arrangement should be enhanced. To this end said controller (19) said controller interrupts said regenerative flow path when a feed pressure at said working port arrangement (6, 7) exceeds a predetermined pressure level.

A hydraulic excavator drive system includes: a first pump connected to a head-side chamber of a boom cylinder; and a second pump that supplies hydraulic oil to one of, or both, an arm cylinder and a bucket cylinder. The first pump is driven by an electric motor. The drive system further includes a switching valve that is in a first position at a boom raising operation and in a second position at a vehicle body lifting operation. The first position is a position in which the switching valve brings a rod-side chamber of the boom cylinder into communication with a tank, and the second position is a position in which the switching valve brings the rod-side chamber into communication with the second pump.

In order to reduce fluid consumption, a fluid return apparatus is provided for a double-acting cylinder having a first fluid connection for supplying fluid to a first cylinder chamber of the cylinder and a second fluid connection for supplying fluid to a second cylinder chamber at a piston rod-side of the cylinder. The fluid return apparatus comprises a first fluid passage providing fluid communication between the first fluid connection and the first cylinder chamber; a rapid venting valve comprising an inlet providing communication with the second fluid connection; an outlet providing communication with the piston-rod-side second cylinder chamber; a vent of the rapid venting valve, connected by a second fluid passage to the first fluid passage; and a non-return fitting in the second fluid passage, which prevents fluid from flowing from the first fluid passage to the rapid venting valve and an auxiliary outlet device.

In order to reduce fluid consumption, a fluid return apparatus is provided for a double-acting cylinder having a first fluid connection for supplying fluid to a first cylinder chamber of the cylinder and a second fluid connection for supplying fluid to a second cylinder chamber at a piston rod-side of the cylinder. The fluid return apparatus comprises a first fluid passage providing fluid communication between the first fluid connection and the first cylinder chamber; a rapid venting valve comprising an inlet providing communication with the second fluid connection; an outlet providing communication with the piston-rod-side second cylinder chamber; a vent of the rapid venting valve, connected by a second fluid passage to the first fluid passage; and a non-return fitting in the second fluid passage, which prevents fluid from flowing from the first fluid passage to the rapid venting valve and an auxiliary outlet device.

An object of the present invention is to provide a work machine that can increase the operation speed of an actuator by a regenerating function while ensuring accuracy of position control of the actuator. For this purpose, a controller computes a target actuator supply flow rate by subtracting a regeneration flow rate from a target actuator flow rate, computes a target flow control valve opening amount on the basis of the target actuator supply flow rate, computes a target pump flow rate equal to or more than the sum of a plurality of the target actuator supply flow rates, controls flow control valves according to the target flow control valve opening amount, and controls a hydraulic pump according to the target pump flow rate.

An object of the present invention is to provide a work machine that can increase the operation speed of an actuator by a regenerating function while ensuring accuracy of position control of the actuator. For this purpose, a controller computes a target actuator supply flow rate by subtracting a regeneration flow rate from a target actuator flow rate, computes a target flow control valve opening amount on the basis of the target actuator supply flow rate, computes a target pump flow rate equal to or more than the sum of a plurality of the target actuator supply flow rates, controls flow control valves according to the target flow control valve opening amount, and controls a hydraulic pump according to the target pump flow rate.

The present invention provides an improved high-low hydraulic system for compacting machinery, such as balers, horizontal balers, compactors, transfer station compactors, and the like. The high-low hydraulic system comprises at least one double rotary pump, a plurality of directional control valves, a pilot-operated back pressure reducing valve, a flow control valve, a plurality of one-way valves, and a plurality of pressure switches. The high-low hydraulic system may be regenerative or non-regenerative and provides many advantages over conventional hydraulic systems. Such advantages include greater system efficiency due to a reduced back pressure during the time of the retraction stroke and clever flow sequencing, mitigation of hydraulic shocks at the beginning and end of compaction and retraction strokes, and reduced cycle time of the cylinder during operation due to the concurrent filling of the rod end side during decompression of the blind end side after the compaction stroke. Moreover, the present high-low hydraulic system allows for the cylinder to operate at three or more independent speeds. Additionally, the present high-low hydraulic system may also comprise an accumulator and pressure transducer that further assist with substantially maintaining a predetermined hydraulic pressure on the blind end side after the completion of the compaction stroke.