Hydraulic systems and methods comprising a source of hydraulic pressure; a hydraulic load; and an energy recovery circuit. The source of hydraulic pressure is fluidly connected to the hydraulic load through a first hydraulic channel with an orifice. The energy recovery circuit includes a recovery channel which is fluidly connected at its first end to the orifice on the side of it which is connected to the source of hydraulic pressure, and which is fluidly connected at its second end to a hydraulic motor.

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.

A regeneration device includes: a regeneration valve that controls the flow rate of an operating fluid being drained from one port of a cylinder; a non-return valve that allows a regenerative flow of the operating fluid from the regeneration valve to the other port of the cylinder and blocks an opposite flow of the operating fluid; and an exhaust valve that controls the flow rate of the operating fluid output from the regeneration valve being drained to a tank. The regeneration valve controls the flow rate independently of the exhaust valve.

A construction machine that makes it possible for an operator to linearly push a bucket simply by operating an arm in a pushing direction is provided. A controller 50 is configured to, in a case where a straight locus is selected by a bucket locus selecting device 52, calculate a constant flow rate ratio α according to a boom initial angle that is an angle of a boom 2 sensed by a boom angle sensor 33 at a time point when an arm 4 is operated in a pushing direction by an operation device 51, and control the delivery flow rate of a first hydraulic pump 12 such that a hydraulic fluid is discharged from a cap chamber 1a of a boom cylinder 1 at a flow rate Qb obtained by multiplying a flow rate Qa of a flow supplied to a cap chamber 3a of an arm cylinder 3 by the flow rate ratio α while the arm 4 is operated in the pushing direction by the operation device 51 and there is not an instruction for operation of the boom 2.

A hydraulic machine is provided. A boom actuator includes a large chamber and a small chamber. A recovery unit receives fluid discharged from the large chamber and then recovers energy. A recovery line connects the large chamber and the recovery unit. An accumulator is connected to the recovery line. A jack-up assist line connects the accumulator and the small chamber. A jack-up assist valve is disposed on the jack-up assist line to block flow of fluid from the accumulator to the small chamber in a first position and allow the flow of fluid from the accumulator to the small chamber in a second position. A controller controls movement of the jack-up assist valve. The controller may determine whether or not the hydraulic machine is in a jack-up condition, and when the hydraulic machine is determined to be in the jack-up condition, moves the jack-up assist valve to the second position.

A hydraulic machine. A boom actuator includes a large chamber and a small chamber. A recovery unit receives fluid discharged from the large chamber and then recovers energy. A recovery line connects the large chamber and the recovery unit. An accumulator is connected to a first point on the recovery line. A discharge valve is disposed on the recovery line between the first point and the recovery unit. A first sensor measures a pressure in the accumulator. A controller controls opening and closing of the discharge valve. The controller performs anti-bouncing control of: determining a target pressure in the accumulator corresponding to a load pressure applied to fluid in the large chamber by a load according to a predetermined correspondence; and controlling the opening and closing of the discharge valve such that the pressure in the accumulator measured by the first sensor reaches the target pressure.

To be capable of dealing with a machine body lifting operation or a sudden operation, while improving energy efficiency, during a boom-lowering operation, and achieving the reduction of the number of parts, in a construction machine equipped with a boom. It is configured such that a first region Y1 at which a recovery valve passage 16e is opened and a supply valve passage 16f is closed and a second region Y2 at which the recovery valve passage 16e and the supply valve passage 16f are opened, are provided at an operating position of a first boom control valve 16 during the boom lowering operation, and the first boom control valve 16 is positioned at the first region Y1 when neither a machine body lifting operation nor the sudden operation is performed during the boom-lowering operation, and at the region Y2 when the machine body lifting operation or the sudden operation is performed.

A hydraulic system includes a first supply line connecting a boom control valve and a bottom side of a boom cylinder, a second supply line connecting the boom control valve and a rod side of the boom cylinder, a leveling switch valve having: a first operating position allowing a leveling operation of a working tool; and a first stopping position allowing the leveling operation to stop, a ride controller including: a ride-control switch valve connected to a branched fluid line branched from the first supply line; and an accumulator configured to perform an anti-vibrating operation for suppressing a pressure fluctuation of the boom cylinder, and a drain fluid line to discharge operation fluid in a downstream section extending from the leveling switch valve to the rod side of the boom cylinder in the second supply line when the leveling switch valve is switched to the first stopping position.

An upper revolving structure (4) of a hydraulic excavator (1) includes a revolving frame (7), a counterweight (8), an operator's seat (12), a right front cover (17B) disposed from the right side of the operator's seat (12) toward a front end side of the revolving frame (7), a control valve device (18), and an accumulator (21). An accumulator support device (23) is provided between the operator's seat (12) and the right front cover (17B), the accumulator support device (23) is configured by a box (24) providing the inside thereof for an accommodating space (25) and having an opening (26) and a lid member (28) mounted on the box (24) through a hinge member (29) and opened and closed between an open position at which the side of a free end (28D) opens the opening (26) and a closed position at which the side of the free end (28D) closes the opening (26), and the accumulator (21) is mounted on the lid member (28).

A hydraulic drive apparatus includes a flow-path selector valve and a flow-path switching control unit that operates the valve. The flow-path selector valve has a first position for a single operation state and a second position for a combined operation state, configured to, at the first position, form a first flow path connected to a first pump, a second flow path connected to a second pump, and a connecting flow path providing communication between the first flow path and the second flow path. When a driving state of a work actuator is deviated from an allowable range in the combined operation state, the flow-path switching control unit reduces an opening area of the connecting flow path as compared with that when the driving state is within the allowable range.