Abstract: An EHA system (10) for lifting or lowering a leg of an aircraft includes a hydraulic circuit (101) having a hydraulic actuator (a hydraulic cylinder 2) configured to lift or lower the leg, at least one electric hydraulic pump (3), and a hydraulic path, a pressure sensor (38, 83), a temperature sensor (84), and a control unit (a controller 9) configured to output a control signal for operating the electric hydraulic pump in leg lifting or lowering. The hydraulic circuit includes a pressure increasing element. The control unit performs health monitoring regarding the performance of the electric hydraulic pump based on the pressure of hydraulic fluid, the temperature of hydraulic fluid, and the speed of the electric hydraulic pump during operation of the electric hydraulic pump.

Abstract: A landing gear lifting/lowering EHA system includes: a hydraulic actuator configured to lift and lower the leg of an aircraft; at least one electrically operated hydraulic pump; a hydraulic path; a pressure sensor attached to the hydraulic actuator or the hydraulic path and configured to output a measurement signal corresponding to hydraulic pressure; and a controller configured to output a control signal to the electrically operated hydraulic pump, wherein, when a state in which the hydraulic pressure exceeds a set pressure continues for a set time, the control unit stops the electrically operated hydraulic pump in operation and resumes the operation of the electrically operated hydraulic pump after the hydraulic pressure drops to or below a second set pressure after the electrically operated hydraulic pump is stopped.

Abstract: A landing gear lifting/lowering EHA system includes: a hydraulic actuator configured to lift and lower the leg of an aircraft; at least one electrically operated hydraulic pump; a hydraulic path; a pressure sensor attached to the hydraulic actuator or the hydraulic path and configured to output a measurement signal corresponding to hydraulic pressure; and a controller configured to output a control signal to the electrically operated hydraulic pump, wherein, when a state in which the hydraulic pressure exceeds a set pressure continues for a set time, the control unit stops the electrically operated hydraulic pump in operation and resumes the operation of the electrically operated hydraulic pump after the hydraulic pressure drops to or below a second set pressure after the electrically operated hydraulic pump is stopped.

Abstract: A hydraulic cylinder includes: a cylinder tube; a piston; a piston rod; a pair of end covers; and a snubbing mechanism configured to reduce the moving speed of the piston after the piston reaches the vicinity of the end of its stroke. The snubbing mechanism includes: a supply/discharge port formed in an associated one of the end covers; a valve configured to open and close the supply/discharge port; a connector configured to connect the valve and the piston together; and at least one recess extending from the edge of the supply/discharge port. When the piston approaches the end of its stroke, the valve closes the supply/discharge port to form a throttle oil passage, and hydraulic oil is discharged through the throttle oil passage to reduce the moving speed of the piston.

Abstract: The electro-hydrostatic actuator system for raising and lowering aircraft landing gear (1) is provided with at least one hydraulic actuator (21, 22) that is constituted so as to perform retraction and deployment of landing gear (11), a hydraulic circuit (33), a hydraulic pump (32), an electric motor (31), a controller (4) constituted so as to control the operation of the electric motor upon receiving an instruction relating to retraction of the landing gear or an instruction relating to deployment of the landing gear, and a sensor (34) that detects the discharge pressure of the hydraulic pump. The controller feeds back the discharge pressure that the sensor has detected, and controls the operation of the electric motor so that the discharge pressure of the hydraulic pump becomes a target discharge pressure.

Abstract: A hydraulic cylinder includes: a cylinder tube; a piston; a piston rod; a pair of end covers; and a snubbing mechanism configured to reduce the moving speed of the piston after the piston reaches the vicinity of the end of its stroke. The snubbing mechanism includes: a supply/discharge port formed in an associated one of the end covers; a valve configured to open and close the supply/discharge port; a connector configured to connect the valve and the piston together; and at least one recess extending from the edge of the supply/discharge port. When the piston approaches the end of its stroke, the valve closes the supply/discharge port to form a throttle oil passage, and hydraulic oil is discharged through the throttle oil passage to reduce the moving speed of the piston.

Abstract: An electro hydrostatic actuator system for retracting/extending a landing gear includes a plurality of hydraulic actuators, a plurality of hydraulic supply sources each including a single hydraulic pump and a single electric motor, provided in parallel to each other and joined at the downstream ends, a plurality of switching valves provided in parallel on a supply path that connects the hydraulic actuators to a junction of the hydraulic supply sources, and a controller configured to sequentially operate the hydraulic actuators. The hydraulic supply sources each include a check valve which prevents operation oil from flowing toward the hydraulic pump. In a normal state, the hydraulic supply sources together supply operation oil sequentially to the hydraulic actuators. When any of the hydraulic supply sources is failed, the other hydraulic supply source(s) other than the failed hydraulic supply source supplies operation oil sequentially to the hydraulic actuators.

Abstract: An electro hydrostatic actuator includes an actuator body, a hydraulic pump driven to supply operation oil to the actuator body, and an electric motor configured to drive the hydraulic pump. Each of the hydraulic pump and the electric motor is placed so as to surround the outer periphery of the actuator body, and the hydraulic pump and the electric motor are arranged in a direction along a center axis.

Abstract: A landing gear retraction/extension device includes a hydraulic actuator, a hydraulic circuit, a hydraulic pump, an electric motor, and a driver. Part of the hydraulic circuit is provided such that heat is exchangeable between operation oil and each of the electric motor and the driver. The driver supplies power to the electric motor before landing of an aircraft such that an operation oil temperature is higher than a predetermined temperature upon the landing of the aircraft.

Abstract: An electro hydrostatic actuator system for retracting/extending a landing gear includes a plurality of hydraulic actuators and a plurality of hydraulic supply sources each including a single hydraulic pump and a single electric motor and provided in parallel to each other. In a normal state, the hydraulic supply sources together supply operation oil sequentially to the hydraulic actuators. When any of the hydraulic supply sources is failed, the other hydraulic supply source(s) other than the failed hydraulic supply source supplies operation oil sequentially to the hydraulic actuators.

Abstract: A landing gear retraction/extension device includes a hydraulic actuator, a hydraulic circuit, a hydraulic pump, an electric motor, and a driver. Part of the hydraulic circuit is provided such that heat is exchangeable between operation oil and each of the electric motor and the driver. The driver supplies power to the electric motor before landing of an aircraft such that an operation oil temperature is higher than a predetermined temperature upon the landing of the aircraft.

Abstract: An electro hydrostatic actuator includes an actuator body, a hydraulic pump driven to supply operation oil to the actuator body, and an electric motor configured to drive the hydraulic pump. Each of the hydraulic pump and the electric motor is placed so as to surround the outer periphery of the actuator body, and the hydraulic pump and the electric motor are arranged in a direction along a center axis.