Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Patent
1996-09-24
1998-07-21
Barefoot, Galen L.
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
244 54, 248559, B64C 2751
Patent
active
057824304
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for antivibratory suspension of a rotor, in particular a main or lifting rotor, of a helicopter on the fuselage thereof, that is to say a suspension device intended to filter vibration between the rotor and the fuselage.
In general, on helicopters, the main rotor, or each main rotor, is integral in rotation with a rotor mast or shaft supported and driven in rotation about its axis, which constitutes the axis of rotation of the rotor, by a gearbox known as main gearbox, coaxial with the rotor mast about the axis of rotation, and linked by at least one transmission shaft to a power plant, supported by the structure of the fuselage of the helicopter, in general on an upper part of the fuselage called transmission support platform, on which is also mounted the assembly consisting of the main gearbox, of the mast and of the rotor.
By reason, essentially, of the alternating forces which are exerted on the components of the rotor while it is rotating, the abovementioned assembly has to be mounted on the fuselage by means of a suspension device filtering the vibration transmitted from the rotor to the fuselage, and in particular the excitations which are longitudinal (with respect to the helicopter) and transverse or lateral, which are the most troublesome.
Amongst the numerous known devices for antivibratory suspension of a helicopter rotor, the devices of the type known as "focal point" type and those of the type known as "antiresonant" type have been the subject of various proposals and embodiments.
A particular focal-point suspension device is described in U.S. Pat. No. 3,698,663 and comprises: around the transmission gearbox and arranged obliquely with respect to the axis of rotation, so as to converge toward the axis of rotation, at a point known as "focal point", each bar being linked by one end to the transmission gearbox and articulated by its other end to a structural support of the fuselage, and allowing transfer to the fuselage of the torque in reaction to the torque driving the rotor by the transmission gearbox as well as the movements of the transmission gearbox with respect to the fuselage with flexibility in at least one direction perpendicular to the axis of rotation in order to filter vibration between the rotor and the fuselage.
In a suspension device of this type, the abovementioned assembly of the main transmission gearbox, of the mast and of the rotor is thus attached to the structure of the fuselage by the set of oblique bars converging at the focal point, around which this suspended assembly can oscillate.
Various focal-point suspension devices, known particularly from U.S. Pat. No. 3,698,663 as well as from FR 2 228 662 and FR 2 232 481, differ from one another in the embodiment of the linking device linking the base or the bottom of the transmission gearbox to the structure of the fuselage.
Thus the "Gazelle" helicopter, from the company AEROSPATIALE Societe Nationale Industrielle, is equipped with an antivibratory suspension device of this type in which, as also described in U.S. Pat. No. 3,698,663, the device linking the base of the transmission gearbox to the fuselage comprises, on the one hand, two identical rods, substantially parallel and extending substantially in the same plane perpendicular to the axis of rotation, one end of each rod being linked to a structural support of the fuselage while its other end is articulated onto one of two lateral supports respectively, fixed to opposite sides of the transmission gearbox, and, on the other hand, at least one elastic link including at least one element for elastic return in at least said direction perpendicular to the axis of rotation and also perpendicular to the direction of the rods, the elastic return element being fixed between a structural support of the fuselage and a lateral support of the base of the transmission gearbox.
The device of the "Gazelle" helicopter exhibits drawbacks, mentioned below, since, as represented in FIG. 2, the two rods 14A, working in tension in order to transmit the t
REFERENCES:
patent: 3920202 (1975-11-01), Mouille
patent: 3921940 (1975-11-01), Mouille
patent: 4431148 (1984-02-01), Mouille
patent: 4458862 (1984-07-01), Mouille
patent: 4500054 (1985-02-01), Osborn
patent: 4720060 (1988-01-01), Yana
patent: 5190244 (1993-03-01), Yana
Barefoot Galen L.
Eurocopter France
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