A hydraulic energy regeneration system for a work machine for boosting a pressure of a return hydraulic fluid of a hydraulic cylinder and regenerating the hydraulic fluid, prevents a bottom pressure from reaching an overload relief set pressure and suppresses a changeover shock to ensure favorable operability. The hydraulic energy regeneration system for the work machine, includes: a communication pressure boost passage that can boost a pressure of a discharge-side hydraulic fluid by communicating a discharge side and a suction side of the hydraulic cylinder with each other during an own weight fall of a driven body; a communication pressure boost valve that is disposed in the communication pressure boost passage and that can regulate one of or both of a pressure and a flow rate of the communication pressure boost passage; a reuse-side line and a reuse control valve or a regeneration-side line and a regeneration control valve that can regenerate a hydraulic fluid discharged from the hydraulic cylinder during the own weight fall of the driven body; and a controller. The controller is configured to reduce an opening degree of the communication pressure boost valve in response to an increase of the discharge-side pressure of the hydraulic cylinder right after the discharge-side pressure reaches a preset high load set pressure, and gradually reduces the opening degree of the communication pressure boost valve with passage of time.

A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic actuator (110), first and second counter-balance valves (300, 400), first and second independent control valves (700, 800), and first and second blocking valves (350, 450). The actuator includes first and second corresponding chambers. In a first mode, the second counter-balance valve is opened by the first control valve, and the first counter-balance valve is opened by the second control valve. In a second mode, at least one of the counter-balance valves is closed. A meter-out control valve (800, 700) may be operated in a flow control mode, and/or a meter-in control valve (700, 800) may be operated in a pressure control mode. Boom dynamics reduction may occur while the boom is in motion (e.g., about a worksite). By opening the counter-balance valves, sensors at the control valves may be used to characterize external loads. The control valves may respond to the external loads and at least partially cancel unwanted boom dynamics. The system may further detecting faults in actuators with counter-balance valves and prevent any single point fault from causing a boom falling event and/or mitigate such faults.

To provide a drift-prevention valve device, a blade device, and a working machine capable of operating an actuated unit and preventing the machine body from drifting with a simple configuration. The drift-prevention valve device is provided with a non-return valve 41 that allows the flow of hydraulic oil from a control valve 28 to a head chamber 34h of a blade cylinder 34 and blocks the flow of the hydraulic oil in the reverse direction; and a piston accommodation part 42 separately disposed from an accommodation part 70 of the non-return valve 41, configured to movably accommodate a power piston 43. The power piston 43 defines a first piston chamber 42p1 communicating with a rod chamber of 34r of the blade cylinder 34 and a second piston chamber 42p2 for drain positioned on a poppet 71 side of the non-return valve 41 and communicating with a tank 52. The power piston 43 is connected to the poppet 71 of the non-return valve 41, so that the power piston 43 can be operated by the difference between the urging force of the poppet 71 by a spring 72 of the non-return valve 41 and a rod chamber pressure of the blade cylinder 34.

A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, a hydraulic pump mounted on the upper turning body, a hydraulic actuator configured to be driven with hydraulic oil discharged by the hydraulic pump, a bleed valve configured to control the flow rate of a portion of the hydraulic oil discharged by the hydraulic pump, the portion flowing to a hydraulic oil tank without going through the hydraulic actuator, and a control device configured to control the opening area of the bleed valve in accordance with the magnitude of pulsation in the pressure of hydraulic oil supplied from the hydraulic pump to the hydraulic actuator.

The present invention provides a controller for a hydraulic apparatus. The controller is configured to determine (410) that a mode change criteria has been met for the hydraulic apparatus. In response to the determination, the controller is configured to control (420) a valve arrangement to change a first actuator chamber of a hydraulic actuator between being fluidly connected to a hydraulic machine and fluidly isolated from a second chamber of the hydraulic actuator, and being fluidly connected to both the second actuator chamber and the hydraulic machine. Further in response to the determination, the controller is configured to control (430) the hydraulic machine to change a flow rate of hydraulic fluid flowing through the hydraulic machine to regulate a movement of the hydraulic actuator during the control of the valve arrangement.

A shovel includes a plurality of hydraulic actuators each configured to move in response to a movement command; a pressure sensor configured to detect a pressure of hydraulic oil in each of the hydraulic actuators; a meter-in valve in correspondence with each of the hydraulic actuators; a meter-out valve in correspondence with each of the hydraulic actuators; and a controller having a plurality of output characteristics set for each of the hydraulic actuators. The controller is configured to calculate a required flow rate corresponding to the movement command, based on an output characteristic corresponding to the movement command from among the plurality of output characteristics.

A stage assembly (10) includes a stage (14), and a fluid actuator assembly (24) that moves the stage (14). The fluid actuator assembly (24) includes a piston housing (32) that defines a piston chamber (34); (ii) a piston (36) that separates the piston chamber (34) into a first chamber (34A) and a second chamber (34B); (iii) a supply valve (38C) that controls the flow of the working fluid (40) into the first chamber (34A); and (iv) an exhaust valve (38D) that controls the flow of the working fluid (40) out of the first chamber (34A). The supply valve (38C) has a supply orifice (250G) having a supply orifice area, and the exhaust valve (38D) has an exhaust orifice (352G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber (34A), (34B).

A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic cylinder (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and a selection valve set (850). The selection valve set is adapted to self-configure to a first configuration and to a second configuration when a net load (90) is supported by a first chamber (116, 118) and a second chamber (118, 116) of the hydraulic cylinder, respectively. When the selection valve set is enabled in the first and second configurations, the second and first control valve may fluctuate hydraulic fluid flow to the second and first chamber, respectively, to produce a vibratory response (950) that counters environmental vibrations (960) of the boom. When the selection valve set is not enabled, the first and second counter-balance valves are adapted to provide the hydraulic cylinder with conventional counter-balance valve protection.

An example valve assembly includes a meter-in valve configured to be fluidly coupled to a first source of pressurized fluid and control fluid flow from the first source of pressurized fluid into a first chamber of an actuator; a counterbalance valve including configured to open and control fluid flow from a second chamber of the actuator to a tank in response to a pilot pressure fluid signal received at a pilot port of the counterbalance valve; and a pressure reducing valve configured to be fluidly coupled to a second source of pressurized fluid and to be fluidly coupled to the pilot port of the counterbalance valve, where the pressure reducing valve is configured to receive pressurized fluid from the second source of pressurized fluid and, when actuated, provide the pilot pressure fluid signal to the pilot port of the counterbalance valve.

An example valve includes a main stage, a pilot stage, and a solenoid actuator. The main stage includes a sleeve and a piston axially movable within the sleeve. The piston defines a cavity therein. The pilot stage includes a pilot pin received at, and axially movable in, the cavity of the piston, where the piston forms a pilot seat at which the pilot pin is seated when the valve is in a closed state. The solenoid actuator includes a solenoid coil, an armature, and a solenoid spring. The solenoid spring applies a biasing force in a distal direction on the pilot pin to seat the pilot pin at the pilot seat. Energizing the solenoid coil causes the armature to move in a proximal direction, thereby reducing the biasing force that the solenoid spring applies on the pilot pin.