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: 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 includes a single-rod cylinder having fixed and movable ends, a hydraulic supply source, and a reservoir provided in a hydraulic circuit and capable of storing operation oil. At a predetermined position of the single-rod cylinder close to the fixed end, the hydraulic supply source is disposed at the periphery of the single-rod cylinder, and is integrated with the single-rod cylinder. The reservoir is formed in a double cylindrical shape, and is, at a position close to the movable end relative to the hydraulic supply source, integrated with the single-rod cylinder in the state in which the single-rod cylinder is inserted into the reservoir so as to be coaxial with the reservoir.

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: The present invention is to provide an electro hydrostatic actuator excellent in a snubbing characteristic including a cylinder type actuator main body 1, a piston 2 having a piston rod, the piston slidingly moving in a cylinder of the actuator main body, a motor 18, a pump 19 for supplying fluid according to the rotation of the motor, a mechanism for adjusting a running amount of the fluid into and from the cylinder according to the motion of the piston, and a reservoir 8 for adjusting the supply of the fluid corresponding to a volume difference generated according to the motion of the piston, and a controller 17 which controls the number of revolutions of the motor according to the calculated load torque, and a snubbing control method used for this. An electro hydrostatic actuator of realizing a snubbing mechanism capable of increasing energy efficiency, when used for a landing gear retraction/extension device of an airplane, can be provided.

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.

Abstract: The present invention is to provide an electro hydrostatic actuator excellent in a snubbing characteristic including a cylinder type actuator main body 1, a piston 2 having a piston rod, the piston slidingly moving in a cylinder of the actuator main body, a motor 18, a pump 19 for supplying fluid according to the rotation of the motor, a mechanism for adjusting a running amount of the fluid into and from the cylinder according to the motion of the piston, and a reservoir 8 for adjusting the supply of the fluid corresponding to a volume difference generated according to the motion of the piston, and a controller 17 which controls the number of revolutions of the motor according to the calculated load torque, and a snubbing control method used for this. An electro hydrostatic actuator of realizing a snubbing mechanism capable of increasing energy efficiency, when used for a landing gear retraction/extension device of an airplane, can be provided.