A hydrostatic drive includes a hydraulic machine, a hydraulic adjusting device, a high-pressure accumulator, an accumulator-closing valve, and an electronic control unit. The hydraulic machine has a swept volume that is adjustable via the hydraulic adjusting device from a maximum positive swept volume to a maximum negative swept volume via a zero swept volume. The hydraulic machine is operated as a pump with positive swept volume and as a motor with negative swept volume. The high-pressure accumulator supplies the hydraulic machine with pressure medium for operation as a motor via a pressure line. The accumulator-closing valve has a first position and a second position and is arranged in the pressure line. A fluidic connection from the high-pressure accumulator to the hydraulic machine is open in the first position and closed in the second position. The accumulator-closing valve is actuated in accordance with signals from the electronic control unit.

The present patent of invention relates to a hydraulic unit (U) with a pneumatic cylinder (15) that works jointly with a servomotor (M), together with a ball screw (29) to together move a hydraulic piston pump (8), made up of a hydraulic plunger (7), with related sealing elements to prevent oil leaks, noise, metal-on-metal attrition and loss of efficiency, that is moved upwards and downwards using a ball screw (29) and a pneumatic cylinder (15), jointly with a servomotor (M) which, when moved, pushes the pressurized oil outwards while filling the opposite hydraulic chamber with an oil suction movement, the pumped oil entering a hydraulic pressure accumulator (25), where it remains idle to be used when required and being supplied by the up/down movement of the piston, generating continuous pumping, which is automatically stopped when the hydraulic pressure accumulator (25) is full and has reached the predetermined hydraulic pressure. With regard to the field of application, the invention is intended to be used to move hydraulic actuators in a variety of different machines and equipment.

The present disclosure relates to diagnosing and locating fluid leakage within a pneumatic system (5) using a minimal amount of pressure sensors (55, 75, 89). In general, each branch (51, 71, 85) of a pneumatic system (5) includes an associated pressure sensor (55, 75, 89) and in accordance with how the pneumatic components (57, 59, 61, 77, 91, 93, 95) associated with the pneumatic branch (51, 71, 85) are toggled and monitored, leaks can be detected and located within the branch (51, 71, 85) using a minimal amount of pressure sensors (55, 75, 89). More specifically, pressure and pressure decay may be measured by the sensors (55, 75, 89) within a branch (51, 71, 85) while the pneumatic components (57, 59, 61, 77, 91, 93, 95) are in a particular configuration. The configuration is thereafter changed, and pressure and pressure decay are again measured by the sensors (55, 75, 89). The results of these two measurements may enable the pneumatic system (5) to derive the presence and location of a leak.

A hydraulic lifting device for a chassis of a mobile device has a valve block, a pump, a tank, a first cylinder device and a second cylinder device. The first cylinder device and the second cylinder device can be selectively pressurized by the pump or connected to tank via the valve block. The first cylinder device is connected to the pump via at least one primary non-return valve disposed in the valve block. The second cylinder device is connected to the pump via at least one secondary non-return valve disposed in the valve block. The valve block has at least one pressure accumulator downstream of the at least one secondary non-return valve in the flow direction from the pump to the second cylinder device. Furthermore, a chassis with such a lifting device and to a mobile device with a chassis is provided.

A hydraulic system includes a first electric machine connected to a first hydraulic machine and a second electric machine connected to a second hydraulic machine. An output side of the second hydraulic machine is connected to an input side of the first hydraulic machine. A hydraulic consumer is hydraulically coupled to an output side of the first hydraulic machine via a supply line and is powered by the first hydraulic machine. A return line hydraulically couples the hydraulic consumer to an input side of the first hydraulic machine. The second hydraulic machine provides a flow of hydraulic fluid to the input side of the first hydraulic machine if a requested flow from the first hydraulic machine exceeds a flow of the return line and recuperates energy if the requested flow from the first hydraulic machine is lower than the flow of the return line.

An energy recuperation system for construction equipment includes an actuator driving upward and downward operations of a work unit; an accumulator connected to the actuator; and a controller determining a predicted downward mode associated with the downward operation of the work unit, regulating a dischargeable lowest limit pressure of the accumulator to a target pressure corresponding to the predicted downward mode, and charging the accumulator having the dischargeable lowest limit pressure regulated to the target pressure with pressurized oil discharged from the actuator during the downward operation of the work unit to recuperate energy, and an energy recuperation method.

A fluid circuit includes a pressure fluid source configured to supply pressure fluid, multiple actuators connected to the pressure fluid source , a direction switching valve configured to switch a supply destination of the pressure fluid supplied from the pressure fluid source , and a discharge amount control mechanism configured to control the output pressure of the pressure fluid source such that a pressure difference ΔP between the output pressure of the pressure fluid source and the maximum load pressure of the load pressures of the multiple actuators reaches a target value ΔPt. The fluid circuit further includes an accumulator configured to accumulate part of return fluid from the actuators.

The invention relates to a hydraulic device for a hydraulic system (12). The hydraulic device includes a chamber arrangement including at least one high-pressure chamber for connection to a high-pressure side of the hydraulic system, and at least one low-pressure chamber for connection to a low-pressure side of the hydraulic system; and a movable member arranged to reciprocate at least partly inside the chamber arrangement in response to pressure variations within the at least one high-pressure chamber and within the at least one low-pressure chamber. The chamber arrangement further includes at least one tank chamber for connection to a tank-pressure side of the hydraulic system.

A fluid pressure circuit includes a directional switching valve arranged between a fixed displacement pump and a fluid pressure actuator and configured to switch a flow passage for a pressurized fluid, an accumulator arranged in a branch flow passage branched from a connection flow passage that connects the fluid pressure actuator and the directional switching valve, an accumulator flow control valve arranged between the connection flow passage and the accumulator, and a pump flow control valve arranged between the fluid pressure actuator and the fixed displacement pump and configured to variably divert a flow rate of the pressurized fluid discharged from the fixed displacement pump into a first system including the tank and a second system including the fluid pressure actuator.

A hydraulic system includes: a high-pressure line; a pump configured to supply pressurized hydraulic fluid to the high-pressure line; a variable displacement hydraulic machine connected by a fluid connection to the high-pressure line for rotationally driving the rotatable load; an electronic control unit; an energy storing device connected to the high-pressure line and configured to communicate with the high-pressure line by receiving energy from the high-pressure line and/or supplying energy to the high-pressure line; and a first detector configured to detect the amount of energy stored in the energy storing device and to transmit a signal indicating said amount of energy stored to the electronic control unit. The electronic control unit is configured to control the volume flow intake of the variable displacement hydraulic machine dependent on a target output of the variable displacement hydraulic machine and on the detected amount of energy stored in the energy storing device.