Patent EP-0233792-A1 (EP)
Inventor: LEMAN JEAN-LUC
IPC: F16F13/06
Filed: 1987-01-08
Abstract: 1. An elastic return strut with a built-in damper of the hydro-elastic type, in particular for a blade of a rotor of an aerodyne having a rotary wing, comprising : - two rigid members (5, 15) each provided with hinge means (6, 16) for connecting one of the rigid members (5) to a first part, such as a blade or a member for connecting said blade to a hub of the rotor, and connecting the other rigid member (15) to a second part such as said rotor hub ; - at least one elastic return member (2), comprising a mass (18) of deformable material which is integral with the two rigid members (5, 15) and is intended to become deformed when said rigid members are displaced with respect to one another and to exert on said rigid members an elastic return force to return them to a relative initial position ; - at least one hydraulic damper (1) comprising two working chambers (24, 25) having a volume variable in opposite senses, which contain a relatively viscous hydraulic fluid intended to pass from one chamber to the other by at least one narrow communication passage (26, 27) between said working chambers when said rigid members are displaced with respect to one another, in order to produce a damping effect on the relative displacement of said rigid members, said damper comprising a cylinder (6) which is carried by one of the rigid members and in which the two working chambers are defined, and a piston (9) is axially sealingly slidingly mounted in a cylinder (3) and separates one working chamber from the other, a rod (11) having a longitudinal axis which is parallel to the axis of the cylinder joining the piston to the other rigid member while passing through at least one of the working chambers ; - a compensating chamber (22) containing a volume (23) of hydraulic fluid and a volume of gas comprising said means for absorbing the thermal expansion of the hydraulic fluid and also intended to compensate the difference in variations in volume between the two working chambers (24, 25), which is due to the rod (11) when the piston (9) is displaced in the cylinder (3) ; - a compensating member (34, 34', 35, 36, 36', 39, 39', 40) which allows hydraulic fluid to flow from one of the working chambers to the compensating chamber when the piston is displaced in the cylinder in one direction and hydraulic fluid to flow from the compensating chamber to a working chamber when the piston is displaced in the cylinder in the other direction ; and - means for absorbing thermal expansion of the hydraulic fluid (22), characterised in that the mass (18) of deformable material of the elastic return member (2) is a cylindrical sleeve (18) made of elastic material, which also forms a closing joint for the hydraulic damper (1), said sleeve (18) being stuck in a sealed manner by its two internal and external surfaces between two metallic tubular lengths (19, 20) which are coaxial along the general axis (XX) of the device, each of which being integral with one of the two rigid members (5, 15) such that said mass (18) operates in a shearing manner only, the compensating chamber (22) being disposed between on the one hand a base (8) of the cylinder (3) adjacent to a working chamber (24) through which the rod (11) passes, and, on the other, a lateral face of the cylindrical elastic sleeve (18) and the internal lateral face of the internal tubular length (19), and the compensating member (39, 39', 40) is disposed in a compensating duct (33) which is made in the piston (9), each of the two ends (34, 34', 38) of which duct is in permanent communication with one of the two operating chambers (24, 25) and a substantially central portion (35) of which is in permanent communication with the compensating chamber (22) by way of a compensating duct (41, 42) in the rod (11) of the piston.