Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Element is an open loop spring curved about rotational axis
Reexamination Certificate
2000-07-07
2001-09-25
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Element is an open loop spring curved about rotational axis
C464S057000, C464S089000
Reexamination Certificate
active
06293871
ABSTRACT:
FIELD OF INVENTION
The invention refers to a torsionally flexible coupling with an outer rim flexibly rotatable against a hub.
DESCRIPTION OF THE PRIOR ART
To provide a plainly constructed torsionally flexible coupling in a driving connection, the attempt has already been made to arrange as a coupling a rubber-flexible disk, which is connected torsion-proof at the hub side to the one, and at the outer rim side the other of the drive trains to be connected. However, such rubber-flexible coupling disks can be applied only for transmission of comparatively low torques. For transmission of higher torques, either complex multi-disk rubber couplings are used, or couplings, the outer rim of which is connected to the hub via radial leaf springs. For damping of this torsionally flexible couplings, the liquid-filled chambers situated between the outer rim and the hub are hydraulically interconnected via choking ducts, so that liquid is displaced between the chambers, as soon as the outer rim and the hub are rotating against each other. Such damped torsionally flexible couplings, however, are complex in terms of construction.
According to DE 43 38 039 a flexible coupling for transmission of torques has been suggested, too, which is equipped with a flexible intermediate body arranged between the hub and the outer ring body, with train components running over one circumferential section each, and substantially engaged at the hub on the one hand, and at the outer ring body on the other hand. These train components running at acute angles to the tangents of the hub have the effect of flexible spokes and are likewise unsuitable for the transmission of higher torques.
Moreover, DE 42 01 597 A indicates a torsional vibraticon damper as already known, which is provided with 2spiral belts fitted into each other, with the gap between the belts being filled with a very viscous liquid. One end of each belt is connected to the other damper half, while the other end remains free, so that damped radial displacements of considerable order are possible. The result is a pure torsional vibration damper, which requires an additional flexible coupling, preferably a rubber coupling, to flexibly couple the two damper halves.
DE 40 06 121 A discloses a torsion damping facility accommodating a helical spring, acting upon the driving part with its inner end, and at the driven part with its outer end, in a damping chamber between a driving and a driven part. In case of a relative movement between the driving and the driven part, the thread of the helical spring in the damping chamber filled with a very viscous liquid makes a radial movement, too, which results in the damping effect. The helical spring creates a torsion damper with large torsion angles between the driving and the driven part, and with a special spring characteristic. This damper doesn's t furnish any new ideas for the construction of a flexible coupling for the transmission of higher torques.
SUMMARY OF THE INVENTION
Therefore, the invention has the task to design a torsionally flexible coupling of the above mentioned type in such a way that even high torques can be transmitted at sufficient torsional flexibility and a small construction volume with little expenditure of construction.
The invention solves the task by providing at least one ring-like compound body between the hub and the outer rim, consisting of at least one spiral layer of an elastomer, with the threads of this spiral layer being connected shear-resistant with a tensionally elastic and flexible intermediate layer filling the space between the threads. The elasticity of tension and of shearing of this intermediate layer is smaller than that of the elastomer layer.
As the flexible intermediate layer between the threads of the spiral elastomer layer are connected shear-resistant with this elastomer layer and has a smaller elasticity of tension and of shearing than the elastomer layer, the major part of the circumferential forces is transmitted via this intermediate layer, thus relieving the elastomer layer and permitting the coupling to transmit a considerably higher torque, at a construction volume equal to that of the rubberflexible coupling disks. The elastic properties of the elastomer layer, concurrent with the elasticity of tension of the intermediate layer ensure a sufficient torsional flexibility of the coupling, which, with corresponding dimensions, can be matched with the respective requirements via the circumferential length of the elastomer layer and the intermediate layer. Depending on the sense of the effective torque, the tensionally elastic and flexible intermediate layer is subject to tensile or compressive stress.
If only one spiral elastomer layer is provided, a certain incidental unbalance must be accepted. Therefore, in case of higher speeds, it is recommended to provide at least two layers of elastomer with corresponding intermediate layers arranged rotationally symmetrical, with the thread lengths of the elastomer layers extending over an angle at circumference exceeding the mutual angular distance of these layers. Due to the resulting overlap of the intermediate layers having a smaller elasticity of tension than the elastomer layers, it is ensured, that the major part of the circumferential forces over the total circumference of the ring-like compound body is transmitted via the intermediate layers.
In order to avoid an excessive constriction of the spiral ellastomer layers during tensile load of the intermediate layers at certain torque loads, two or more concentrically arranged compound bodies may be provided instead of one compound body, which are each interconnected via an intermediate ring, so that the angle of contact of the spiral layers in the area of the individual ring-shaped compound bodies is limited, and the spiral layers are supported at these intermediate rings. Thus the bending moment in the clamping area of the intermediate layers is significantly reduced, resulting in an immediate relief of these intermediate layers. Of course, the supporting effect of the intermediate rings sub-dividing the compound body into individual rings is also utilized in case of a torque load of the coupling in terms of a compressive stress of the intermediate layers, to prevent an undue untwining of the spiral threads.
The tensionally elastic intermediate layers between the spiral elastomer layers may be set up differently. However, especially favorable constructional features are achieved, if these intermediate layers are made of fiber reinforced plastic or of spring steel. Using fiber reinforced plastic in particular, the compound body can be easily built up by means of a winding procedure. The shear-resistant connection between the individual layers doesny's t raise any problems in this context.
REFERENCES:
patent: 3354670 (1967-11-01), Fawick
patent: 4194372 (1980-03-01), Hannibal
patent: 40 06 121 (1991-08-01), None
patent: 42 01 597 (1993-07-01), None
patent: 43 38 039 (1995-05-01), None
patent: 223424 (1991-01-01), None
Browne Lynne H.
Collard & Roe P.C.
Dunwoody Aaron M
Ellergon Antriebstechnik GmbH
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