Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Reexamination Certificate
1999-08-16
2001-10-23
Swiatek, Robert P. (Department: 3643)
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
C244S017110, C244S158700, C416S13400R, C384S037000
Reexamination Certificate
active
06305640
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a spring component for support bearings, particularly of helicopter tail rotors, as well as a support bearing for a helicopter tail rotor or for a support structure for use in outer space.
BACKGROUND INFORMATION
Support bearings with elastic components are used specially in construction of helicopter rotors. Bearingless tail rotors of helicopters essentially comprise belts which are fastened to the rotor mast with a few bolts. The belts run inside of rotor blades, of which the ends on the side of the rotor mast comprise a control sleeve. The torsion of the rotor blades required for control purposes is attained through a torsion of the control sleeve. The belts give the tail rotor the required strength and they are elongated through the centrifugal force and bending moments arising during the rotation. A twisting of the belt by up to about 25° takes place in connection with a rotating of the rotor blade by means of the control sleeve. In connection therewith a relative torsion between the control sleeve and the belt must be guaranteed and at the same time the sleeve must be supported in the transverse direction, i.e. in the flapping direction of the rotor. The connection between the belt and the control sleeve is provided by a support bearing, through which the belt is held in the control sleeve. Through the strong centrifugal and bending forces, which arise at this location of the rotor, the support bearings are exposed to high loads.
Typically, elastomer bearings are used as support bearings, of which the contact support components are made out of layers of titanium or steel plates, between which respectively an elastic material, for example rubber, is located. The belt is held in the middle of the control sleeve between oppositely lying elastomer bearing components. Due to the strong loads, special materials must be used for such type of elastomer sleeve support bearing and moreover, they must comprise a special structure to withstand the loads. These known elastomer bearings are therefore extremely costly, since they require a cost intensive development and manufacture. Moreover they comprise the disadvantage, that they change their stiffness and their material properties at different temperatures. The results are a reduced service life due to additional arising stresses.
To reduce manufacturing costs in the serial production of helicopter tail rotors, it was tried in new developments to substitute the elastomer bearings by twistable supports. Such a concept is described in “DEVELOPMENT OF BEARINGLESS TAIL ROTORS”, Huber et al. Two day International Conference on Helicopter Yaw Control Concepts, Feb. 28, 1990, London. In such contact support components, likewise very high additional stresses arise in the contact support component in connection with a relative twisting of belt, however, which leads to premature material fatigue and increased cracking danger. The service life of conventional support bearings in the area of helicopter tail rotors is thus limited and can be held in a reasonable range only through expensive material compositions.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention, to overcome the above mentioned disadvantages and to provide a spring component for support bearings and a support bearing for helicopter tail rotors and support structures, in which the manufacturing costs are reduced and a secure and durable, movable bearing support of components with a high supporting force is guaranteed.
This object is achieved by the spring component and the support bearing according to the invention.
The spring component according to the invention encompasses:
at least two contact support components for connection with structural components that are to be propped or supported;
one web plate, which connects the contact support components over their width;
wherein a pair of lengthwise webs running in the longitudinal direction is formed in the web plate, which lengthwise webs are connected by first connecting webs running in the direction of the width;
and wherein a further connecting web is arranged at a section located between the first connecting webs of at least one lengthwise web, i.e. in an area of the lengthwise web that lies between the junction lugs of the further connecting webs on the lengthwise web, which further connecting web extends outwardly in the direction of one of the contact support components, so that a twisting of the lengthwise web takes place in connection with a transverse bending moment acting on the spring component.
Advantageously both the lengthwise webs are connected with each other at their ends respectively by a first connecting web, wherein the further connecting web preferably is arranged at a central section, or rather in the middle of the respective lengthwise web. Thereby, a rectangular web frame is formed between the contact support components for receiving the forces via the further connecting webs. The further connecting web can extend up to the contact support component and form the combination to the contact support component, or it can be connected with a further lengthwise web, which then preferably forms the connection to the contact support component. In this case, an especially strong connection results between the web plate and the bordering contact support component, preferably over the entire length of the further lengthwise web.
Advantageously the web plate has essentially a rectangular shape, wherein preferably the mutual spacing distance of the components is determined by the width of the web plate, and wherein particularly the lengthwise webs and the connecting webs are formed by at least one slot or slit running in a longitudinal direction in the web plate. Thereby, in a simple manner a one-piece web plate can be formed, whereby the danger of cracking and also the costs are reduced since the web plate is manufactured in a simple and rational way. Advantageously the further connecting web is formed by two slots or slits which run toward each other from the free edges of the web plate.
Preferably the contact support components have contact bearing areas which face in opposite directions, wherein the web plate is arranged perpendicularly to the contact bearing areas. Thereby the arising forces can be taken up by the contact bearing areas and the web plate in an advantageous way and an especially high support force is provided in the area of the spring component. The contact bearing areas or rather contact support components can be connected with the components to be supported by clamping, adhesive bonding or bolting. Preferably one or more expansion joints are arranged in the contact support components or rather contact bearing areas for the components, whereby the expansion joints preferably extend in the transverse direction.
Thereby, different heat expansions of the spring component relative to the component with which it is connected are equalized.
Preferably the length l of the lengthwise webs is so chosen that the spring component has the desired transverse bending stiffness, and the width b of the connecting webs and the height h of lengthwise webs can be so chosen, that the spring component has the desired elongation stiffness. Consequently the elastic properties of the spring components can be adjusted through suitable selection of the dimensions of the various webs. In this regard, the width b of the connecting webs is preferably about {fraction (1/15)} to ⅕ of the length l of the lengthwise webs, particularly preferably about ⅛ to ¼ and especially preferably about ⅓ of the length of the lengthwise webs. The spring component is preferably manufactured of a fiber composite material, whereby a very high support strength and advantageous material properties are achieved together with an especially lightweight construction and low costs.
According to a further aspect of the invention, a support bearing is provided which encompasses a spring component according to the invention. In the support beari
Eurocopter Deutschland GmbH
Fasse W. F.
Fasse W. G.
Swiatek Robert P.
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