A hydraulic system includes a hydraulic pump, a first hydraulic actuator, a second hydraulic actuator, a first control valve to control the first hydraulic actuator, a second control valve to control the second hydraulic actuator, a return fluid tube in which a return fluid discharged from the first hydraulic actuator flows, the return fluid tube connecting the first control valve and the first hydraulic actuator, a first inner fluid tube provided in the first control valve and connected to the return fluid tube, an outer fluid tube connected to the first inner fluid tube, the outer fluid tube connecting the first control valve and the second control valve, a return-discharge fluid tube to discharge the return fluid, the discharge fluid tube being branched from the outer fluid tube, and a throttle provided in the return-discharge fluid tube.

A safe hydraulic drive system and process, comprising at least one first cylinder chamber and a second, separate cylinder chamber which are connected to one another via a connecting line to form a fluid-filled hydraulic circuit, and a hydraulic drive for conveying the fluid from one cylinder chamber, via the connecting line, into the other cylinder chamber in which the connecting line is arranged. The connecting line has at least one parallel system, between the hydraulic drive and one of the two cylinder chambers, including at least one first sub-connection with at least one first stop valve and a second sub-connection with a baffle arranged therein. The connecting line, excluding the second sub-connection, has a first flow resistance and the second sub-connection has a second flow resistance due to the baffle arranged therein, which is greater than the first flow resistance for the fluid, wherein the drive system is provided with at least one open first stop valve in normal mode and with a closed first stop valve in safe mode for conveying the fluid, and a suitably high second flow resistance has been selected so that a maximum permissible speed for a piston rod is not exceeded in safe mode, even when an external force acts on the drive system in the direction of movement of the piston rod.

The present disclosure relates to a hydraulic circuit, comprising: a motion control valve including a valve spool and a hydraulic actuator for actuating the valve spool, and a hydraulic control device having an outlet fluidically connected to the hydraulic actuator, the hydraulic control device comprising a pressure-reducing valve or a pressure compensated flow control valve.

A power transfer unit includes a first hydraulic circuit, a second hydraulic circuit fluidly connected to the first hydraulic circuit, a pump and motor assembly fluidly connected between the first hydraulic circuit and the second hydraulic circuit, an isolation valve arranged along the first hydraulic circuit and fluidly connected to an inlet of the pump and motor assembly. The isolation valve is movable between a closed position and an open position to prevent and enable high-pressure fluid flow to the inlet, respectively. An unloader valve is arranged along the second hydraulic circuit and fluidly connected to an outlet of the pump and motor assembly, and an orifice is arranged along the second hydraulic circuit and fluidly connected to the unloader valve to reduce back pressure in the second hydraulic circuit.

A hydraulic-mechatronic system, for a vehicle that is connected to a target system, includes a housing with a fluid reservoir containing fluid, a communication port, a hydraulic pump, an electric motor for driving the hydraulic pump, at least one check valve, and a relief valve fluidly connected to the target system and the fluid reservoir. The relief valve moves between a first valve position, which is inactive and directs fluid to the communication port, and at least a second valve position, which is active and directs fluid from the communication port to the fluid reservoir. The hydraulic pump may rotate in forward and reverse directions. During operation of the hydraulic pump in the reverse direction, the relief valve is active such that the hydraulic-mechatronic system limits delivery of fluid through the communication port and instead directs fluid flow into the fluid reservoir of the housing.

[Object] To make it possible to detect, with a single pressure sensor, a malfunction of two solenoid valves for switching flow paths and to quickly and reliably exhaust residual pressure in an air device through a solenoid valve.

[Solution] A residual pressure exhaust air circuit 1 includes: a main flow path 9 through which air from an air source 2 is supplied to an air cylinder 100; an exhaust flow path 10 through which air in the air cylinder 100 is exhausted; a first sensor 8 for detecting a malfunction of solenoid valves 12, 13; a detection flow path 11 through which air from the air source 2 is supplied to the first sensor 8; and the two solenoid valves 12, 13 that switch communication states among the main flow path 9, the exhaust flow path 10, and the detection flow path 11. The two solenoid valves 12, 13 are formed of two-position valves having first positions 12a, 13a at the time of OFF and second positions 12b, 13b at the time of ON and are synchronously ON/OFF controlled. When the two solenoid valves 12, 13 do not operate in synchronization with each other, the air from the air source 2 is supplied to the first sensor 8 to detect a malfunction of the two solenoid valves 12, 13, and at the same time, the air in the air cylinder 100 is exhausted through the solenoid valve 12, 13.

A hydraulic valve assembly includes a connection section, a first valve section, at least one second valve section, and a hydraulic pilot control device with a pilot valve device. The first valve section has a first spool piston and a first spool diverter. The second valve section has a second spool piston and a second spool diverter. The first spool diverter and the second spool diverter are each switchable to at least a first spool diverter switching position and a second spool diverter switching position. Pilot pressure is applied in parallel to the first spool diverter and the second spool diverter via the hydraulic pilot control device in a first switching position of the pilot valve device for switching together into the first spool diverter switching position.

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).

Provided is a hydraulic drive device, wherein the hydraulic drive device is provided with: a cylinder (101); a rod (103); a piston (102); a hydraulic pump (107); a tank (113); a valve (106) that can be switched between a positive state of connecting the hydraulic pump (107) and a head chamber (101h) and connecting a rod chamber (101r) and the tank (113), and a negative state of connecting the hydraulic pump (107) and the rod chamber (101r) and connecting the head chamber (101h) and the tank (113); and a confluence channel (114) at which, when the valve (106) is in the positive state, at least a portion of hydraulic oil going from the rod chamber (101r) to the tank (113) is merged into hydraulic oil going from the hydraulic pump (107) to the head chamber (101h).

A hydraulic system (e.g., of an aircraft or other vehicle) includes a pump, a pressure line coupled to the pump and configured to distribute pressurized hydraulic fluid, and a return line configured to return hydraulic fluid to a reservoir. The hydraulic system also includes an auxiliary leakage valve coupled to the pressure line, to the return line, and to an actuator. The auxiliary leakage valve is configured to receive a control signal and, based on the control signal, selectively open a restricted fluid path. The restricted fluid path couples the pressure line to the return line to allow a restricted amount of the hydraulic fluid to flow from the pressure line to the return line.