Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Reexamination Certificate
2000-06-08
2001-12-04
Barefoot, Galen (Department: 3644)
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
C244S054000
Reexamination Certificate
active
06325327
ABSTRACT:
The invention relates to an anti-vibration or anti-resonating suspension device for a main rotor of a helicopter, comprising a rotor mast driven in rotation by means of a main gearbox about the axis of the mast which is the axis of rotation of the rotor.
An anti-vibration suspension device of this type is designed to be mounted on a helicopter, the structure of which supports, in general, on a mechanical floor on top of the fuselage, motor-driven propulsion components, the main rotor and the main gearbox, acting as a gear and located between the motor-driven propulsion components and the main rotor in order to drive the latter in rotation. An anti-vibration suspension device of this type is therefore inserted between the main gearbox and the helicopter structure, on the one hand to transmit static forces and torques, acting on the rotor, between the rotor and the structure and, on the other hand, to provide an effective damping or filtering action of the dynamic components of the forces and torques acting on the rotor and in particular the dynamic component of the force directed along the rotor axis (pumping) and the forces and torques excited in the plane of the rotor.
The invention relates more specifically to an anti-vibration suspension device of the type comprising a set of at least three oblique bars for supporting the gearbox on the structure of the helicopter, these oblique bars being distributed around the gearbox and inclined relative to one another on the side of their top ends, these oblique bars being articulated, on the one hand to the gearbox by means of their top ends, and on the other hand to the helicopter structure by their bottom ends and by means of levers, a same number of these being provided as there are oblique bars, each lever supporting at least one vibrating weight at one end and being pivotably joined to the structure by its opposite end part, in the vicinity of which the bottom end of a corresponding oblique bar is pivotably mounted on the corresponding lever, the joints linking each lever to the structure and to the corresponding oblique bar being articulated joints which pivot at least about pivot axes substantially perpendicular to a corresponding plane passing through the longitudinal axis of the corresponding oblique bar and the vertical projection of said longitudinal axis onto said structure.
Suspension devices of this type are known from U.S. Pat. No. 4,458,862 and U.S. Pat. No. 4,431,148, in which each oblique bar is articulated at its top end directly on the upper part of the gearbox and at its bottom end at the outer radial end, relative to the rotor axis, of one of a respective number of arms, equal in number to the number of oblique bars, and arranged radially around the base of the gearbox to which these arms are linked. Each arm is pivotably mounted on the structure in the region of its external radial end, which is rigid, and to which the corresponding lever is attached or made integral by its end opposite that supporting the corresponding vibrating weight.
In U.S. Pat. No. 4,458,862, the arms are substantially co-planar radial extensions of the central part of a suspension plate of the gearbox on the structure, this central part being joined to the base of the gearbox, and the arms, arranged in a star design around this central part, being rigid in their plane but flexible in a direction perpendicular to this plane, i.e. in the direction of the rotor axis. Accordingly, each arm constitutes a flexible blade between the central part of the plate fixed to the gearbox and the rigid, external radial end-part of the arm which is pivotably mounted on the structure and on the bottom end of the corresponding oblique bar, and to which is attached or with which is integral the end of the lever at the end opposite the vibrating weight, the lever being oriented substantially radially either towards the interior (towards the rotor axis) or towards the exterior. The articulated joints of each arm permit deflections thereof by deformation in a direction perpendicular to the plane of the part thereof forming a flexible blade, and the unit comprising the corresponding lever and its vibrating weight form an anti-resonance or vibrating system, acting by inertia, and building up inertial forces which counter-balance the reactions at the linkage points to the structure corresponding to the deformations of the flexible blades of the plate.
U.S. Pat. No. 4,431,148 proposes an anti-resonant suspension device of this type which is simplified due to the fact that the suspension plate is independent of radial arms and comprises a thin membrane, which deforms by bending when subjected to forces exerted perpendicularly to its plane or pivoting moments exerted around its centre by the gearbox but is rigid under the effect of traction/compression when subjected to forces and torques exerted in its plane, such as the torque in reaction to the rotor driving torque, this membrane being integrated in the upper structure of the fuselage.
As a result, each radial arm is directly linked to the base of the gearbox by means of a support bearing, which not only provides a pivot axis perpendicular to the radial plane containing this arm but also a flexible link which imparts a certain freedom of movement to the arm, both at an angle and longitudinally, for example a laminated bearing with combined support spherically and in translation.
Each radial arm may be made from a single piece having a flexible part on the one hand and, on the other hand, a rigid part at points of which the arm is pivotably mounted on the corresponding oblique bar and on a corresponding structural bearing, and to which the lever comprising the support for the corresponding vibrating weight is attached. In a preferred embodiment of the above-mentioned patent, however, each radial arm is formed by a flexible radial blade and by a rigid part of a lever, the other part of which constitutes the support for the corresponding vibrating weight, the outer radial end (relative to the rotor axis) of the blade being secured to the lever in the region where the latter is pivotably mounted on the structural bearing of the fuselage.
This design involves using a complex laminated support bearing to provide the link between the inner radial end of each flexible blade to the gearbox, which fulfills a ball joint function and permits parasitic movement of the inner end of the flexible blade along its longitudinal axis when the blade is deformed due to bending.
This arrangement also involves using flexible blades which are difficult to design in terms of dimension and manufacture. Furthermore, the mounting between the lever and the corresponding radial arm can cause problems due to fretting.
The underlying problem of the invention is to simplify an anti-vibration suspension device of this type, in particular by dispensing with blades which flex under bending and also their complex support bearing on the base of the gearbox, thereby achieving very substantial savings on manufacturing, fitting and maintenance costs.
Another objective of the invention is to propose a simplified anti-vibration suspension device which is still compatible with the use of a membrane as proposed in U.S. Pat. No. 4,431,148 in order to absorb the reaction to the driving torque and the forces acting on the base of the gearbox whilst securing the requisite degree of freedom in terms of pumping and rotation, the simplified device proposed by the invention simultaneously and advantageously being compatible with mono- or bi-directional suspensions comprising a pair of identical and parallel rod linkages pivotally mounted between the base of the gearbox and the structure, as described in U.S. Pat. No. 5,782,430, and U.S. Pat. No. 5,788,182, bringing additional savings compared with using a membrane.
To this end, the invention proposes an anti-vibration suspension device of the type outlined above, which is characterised in that each lever is also linked to the structure by at least one torsion spring, biased about a torsion axis that is substantially
Ortega Edwin
Zoppitelli Elio
Barefoot Galen
Eurocopter
Piper Marbury Rudnick & Wolfe
LandOfFree
Anti-vibration suspension device with torsion springs... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Anti-vibration suspension device with torsion springs..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anti-vibration suspension device with torsion springs... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2586998