Patent ID: 6152696
Filing Date: 2000-11-28
Classification: B64C

Abstract:
A device for controlling a pitch of a plurality of blades of an aircraft rotor on which each blade is, firstly, rotated around an axis of rotation of a shaft of the rotor by means of a hub rotating integrally with the shaft, and, secondly, rotating integrally, around a longitudinal blade pitch change axis, with at least one pitch lever controlled by a corresponding pitch rod, connected to a plate rotating with the rotor and belonging to a swash-plate assembly in which the rotating plate is rotary mounted on a non-rotating plate, restrained against any rotation around the rotor axis, the two plates being annular, surrounding the rotor axis, and being oscillating mounted by the non-rotating plate on a central ball joint, centered on the rotor axis and mounted sliding parallel to the rotor axis around a cylindrical guide coaxial to the rotor axis and non-rotating around said rotor axis, so that the swash-plates can be translated parallel to the rotor axis and tilted in any direction around the rotor axis, being activated by control actuators connection the non-rotating plate to a structure of the rotor aircraft, for the control of a collective pitch and a cyclic pitch respectively of the blades, wherein the ball joint is immobilized in rotation around said rotor axis, on said guide, and the non-rotating plate is mounted pivoting, around a first diametrical axis of the ball joint, on two parts diametrically opposite in relation to the center of the ball joint and simultaneously locked against rotation, around the rotor axis, on the ball joint and guided pivoting around a second diametrical axis of the ball joint, which second axis is perpendicular to said first diametrical axis and to the rotor axis, by guide means on the ball joint, said guide means guiding each of said parts on one of two trajectories respectively in circular arcs diametrically opposite in relation to the center of the ball joint and concentric around said second diametrical axis, wherein each guided part includes a trunnion, engaged to pivot in one of two bores respectively of the non-rotating plate, which the bores emerge in an internal radial face of said non-rotating plate, and are diametrically opposite in relation to the center of the non-rotating plate and coaxial around a diametrical axis of said non-rotating plate which the diametrical axis is merged with said first diametrical axis of the ball joint, so as to enable the non-rotating plate to pivot on the trunnions of the guided parts.