PLUG-IN COUPLER FOR CONNECTING SHAFTS
20210048074 ยท 2021-02-18
Inventors
Cpc classification
F16D1/0894
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
Abstract
A coupler for coupling shafts comprises a virtual main axis, a coupler body, and a shaft socket provided in the coupler body, which is configured and arranged for plugging-in a shaft along the main axis and which includes a leaf spring. The leaf spring has a direction of main extension extending tangentially to a virtual arc of a circle around the main axis. The leaf spring is rigidly supported at the coupler body, and configured and arranged for engaging a circumferential surface of the shaft plugged in the shaft socket.
Claims
1. A coupler for coupling shafts, the coupler comprising: a virtual main axis, a coupler body, and a first shaft socket provided in the coupler body, configured and arranged for plugging-in a first shaft along the main axis and including a first leaf spring, wherein the first leaf spring has a direction of main extension extending tangentially to a virtual arc of a circle around the main axis, wherein the first leaf spring is rigidly supported at the coupler body, and wherein the first leaf spring is configured and arranged for engaging a circumferential surface of the first shaft plugged in the first shaft socket.
2. The coupler of claim 1, wherein the first leaf spring is an integral part of the coupler body.
3. The coupler of claim 1, wherein the first leaf spring has a transverse extension direction which is parallel to the virtual main axis.
4. The coupler of claim 3, wherein the first leaf spring has a plane shape extending along its direction of main extension.
5. The coupler of claim 1, wherein the first leaf spring, at both of its ends in its direction of main extension, is supported at the coupler body.
6. The coupler of claim 1, wherein the first shaft socket comprises a second leaf spring which is axially symmetrically configured and arranged with regard to the first leaf spring.
7. The coupler of claim 1, wherein the first shaft socket has an outer shaft guide including first cylindrical surfaces at its free axial end in front of the first leaf spring, wherein the first cylindrical surfaces are partial surfaces of a first virtual cylinder coaxially arranged with regard to the main axis, whose radius is larger than a distance of the first leaf spring to the main axis.
8. The coupler of claim 7, wherein the first shaft socket, at its inner axial end behind the first leaf spring, has an inner shaft guide including a second cylindrical surface, wherein the second cylindrical surface is at least a part of a surface of a second virtual cylinder coaxially arranged with regard to the main axis, whose radius is smaller than the distance of the first leaf spring to the main axis.
9. The coupler of claim 1, wherein the coupler is fixed to a second shaft coaxially arranged with regard to the main axis.
10. The coupler of claim 1, wherein a second shaft socket configured and arranged for plugging-in a second shaft along the main axis is provided in the coupler body and facing away from the first shaft socket.
11. The coupler of claim 10, wherein the second shaft socket is symmetrically configured and arranged with regard to the first shaft socket.
12. The coupler of claim 10, wherein, in a projection along the main axis, the first leaf spring of the first shaft socket and a first leaf spring of the second shaft socket are parallel or orthogonal to each other.
13. The coupler of claim 10, wherein the first leaf spring of the first shaft socket and a first leaf spring of the second shaft socket are arranged at same or different distances to the main axis.
14. The coupler of claim 1, wherein the coupler body comprises a solid-body joint arranged between the first shaft socket, on the one hand, and a second shaft or a second shaft socket facing away from the first shaft socket in the direction of the main axis, on the other hand.
15. A coupling device comprising a coupler, the coupler comprising: a virtual main axis, a coupler body, and a first shaft socket provided in the coupler body and including a first leaf spring, wherein the first leaf spring has a direction of main extension extending tangentially to a first virtual arc of a circle around the main axis, and wherein the first leaf spring is rigidly supported at the coupler body, and a first shaft fitting into the first shaft socket, the first shaft comprising: a virtual first shaft axis, and a circumferential surface having a first flattening extending tangentially to a second virtual arc of a circle around the first shaft axis and wherein the first leaf spring of the first shaft socket engages the circumferential surface of the first shaft and at least locally abuts at an elastic pre-stress against the first flattening of the circumferential surface of the first shaft plugged in the first shaft socket.
16. The coupling device of claim 15, wherein the first leaf spring has a plane extension along its direction of main extension, and wherein the first leaf spring abuts against the first flattenings in two areas which are arranged at a distance in the direction of the second virtual arc of a circle.
17. The coupling device of claim 15, wherein, in a first end region of the first shaft, a maximum radius of the first shaft decreases towards a free axial end of the first shaft.
18. The coupling device of claim 15, wherein the first flattening tapers off in two rotational directions around the first shaft axis at same or at different gradients of a distance to the first shaft axis.
19. The coupling device of claim 15, wherein the first flattening is delimited towards a free axial end of the first shaft by a snap-fit flange in which a radius of the first shaft increases beyond a distance of the first flattening to the first shaft axis, wherein the first leaf spring snap-fits behind the snap-fit flange when plugging the first shaft into the first shaft socket.
20. The coupling device of claim 15, wherein the first leaf spring is an integral part of the coupler body and, at both of its ends in its direction of main extension, supported at the coupler body, wherein the first shaft socket comprises a second leaf spring which is axially symmetrically configured and arranged with regard to the first leaf spring, wherein the first shaft socket has an outer shaft guide including first cylindrical surfaces at its free axial end in front of the first leaf spring, wherein the first cylindrical surfaces are partial surfaces of a first virtual cylinder coaxially arranged with regard to the main axis, whose radius is larger than a distance of the first leaf spring to the main axis, and wherein the first shaft socket, at its inner axial end behind the first leaf spring, has an inner shaft guide including a second cylindrical surface, wherein the second cylindrical surface is at least a part of a surface of a second virtual cylinder coaxially arranged with regard to the main axis, whose radius is smaller than the distance of the first leaf spring to the main axis.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. In the drawings, like reference numerals designate corresponding parts throughout the several views.
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DETAILED DESCRIPTION
[0033] According to the present invention, a coupler for coupling shafts comprises a virtual main axis, a coupler body and a shaft socket provided in the coupler body. The first shaft socket comprises at least one leaf spring which is supported at the coupler body and which is configured and arranged for engaging a circumferential surface of a first shaft plugged in the first shaft socket. The at least one leaf spring has a direction of main extension extending tangentially to a virtual arc of a circle around the main axis. The first leaf spring of the coupler according to the invention has an essentially plane shape extending along its direction of main extension. The leaf spring is supported at the coupler body comprising the first shaft socket into which the first shaft can be plugged-in. Thus, the first leaf spring rotates together with the coupler body about the main axis. The leaf spring engages the circumferential surface of the first shaft extending around the main axis, i. e. the first leaf spring engages the first shaft from the outside, when the first shaft is plugged into the first shaft socket. By means of this engagement of the leaf spring at the first shaft, torque can be transferred between the first shaft and the coupler body. Besides the stiffness of the leaf spring, the size of the torque which can be transferred depends on the shape or course of the circumferential surface of the first shaft. If the circumferential surface of the first shaft has a flattening against which the first leaf spring can abut a certain angle of rotation position of the first shaft with regard to the coupler body is defined via this abutment. In other words, the coupler according to the invention is free of play. If the first shaft has a tapering free end, this papering free end can be inserted into the first shaft socket independently of whether the defined rotational angle position is kept or not. Via the tapering free end, the first shaft elastically deflects the first leaf spring. With a small deviation of the shaft from the defined rotational position with regard to the coupler body, a relative rotation of the shaft with regard to the coupler body, which results in an abutment of the first leaf spring at the fattening of the first shaft, automatically results. Otherwise, this abutment may be caused by a torque applied between the first shaft and the coupler body.
[0034] The formulation a direction of main extension extending tangentially to a virtual arc of a circle around the main axis means that the direction of main extension extends along a tangent line to the virtual arc of a circle around the main axis. The feature of the coupler according to the present invention defined by this formulation does not require that the direction of main extension is a straight direction exactly running in parallel to a tangent line to the virtual arc of a circle around the main axis. Instead, it is sufficient if the direction of main extension essentially is a straight direction and essentially runs in parallel to such a tangent line. Generally, all formulations indicating a movement or extension along a particular direction do not require that the movement or extension is exactly in the indicated direction. It is sufficient if the movement or direction essentially is in that direction.
[0035] The adjective virtual used in defining certain features of the coupler according to the present invention indicates that the respective object is no object which could be seen or even grabbed as such. Nevertheless it can be clearly determined whether the coupler according to the present invention has these virtual features or not.
[0036] The first leaf spring has a transverse extension direction orthogonal to its direction of main extension. This transverse extension direction extends along the virtual main axis. Preferably, the transverse extension direction of the leaf spring is parallel to the virtual main axis.
[0037] Preferably, the first leaf spring is supported at the coupler body at both of its ends in its direction of main extension. The leaf spring supported at both of its ends has a higher effective stiffness with regard to deflections away from the main axis as compared to its modulus of elasticity than a leaf spring only supported at one of its ends. Further, a leaf spring supported at both of its ends is suitable for an abutment against both ends of a flattening of the first shaft such that the defined rotational angle position of the first shaft with regard to the coupler body is precisely kept up to reaching a maximum torque which can be transferred by the coupler according to the invention. The defined rotational angle position of the first shaft with regard to the coupler body may also precisely be kept up to reaching the maximum torque transferable by means of the coupler according to the invention in that the leaf spring has a shaped abutment area which flatly abuts against the flattening of the first shaft at a pre-stress. Such an abutment area may also be provided at a first leaf spring which is supported at the main body at one of its ends only.
[0038] The first leaf spring is rigidly, i. e. neither via a joint nor otherwise movable, supported at the coupler body. Essentially, the coupler body is only moveable due to the elastic deformability of the first leaf spring, which, however, is sufficient for its function, and otherwise the coupler body is a rigid unit. Preferably, the leaf spring is not only supported at the coupler body but an integral part of the coupler body. For example, the first leaf spring may be formed in one piece together with the coupler body. Particularly, the coupler body and the first leaf spring may be milled out of a blank with a uniform composition or molded in a mold from a single material. However, in forming the coupler according to the invention in a mold, different materials may also be used. For example, a first leaf spring made of metal may be embedded at its ends by injecting plastic to form the remainder of the coupler body.
[0039] If the first shaft socket has a second leaf spring which is axially symmetrically configured and arranged with regard to the first leaf spring, the coupler according to the invention is suited to compensate for angle errors and eccentricities of the first shaft with regard to the main axis of the coupler by means of elastic deformations of the leaf springs.
[0040] For the purpose of making it easy to plug-in the first shaft into the first shaft socket, the first shaft socket may have an outer shaft guide including first cylindrical surfaces at its free axial end in front of the leaf spring. This first cylindrical surfaces are partial surfaces of a first virtual cylinder coaxially arranged with regard to the main axis. The radius of this first cylinder is larger than a distance of the first leaf spring to the main axis. It is to be understood that the radius of the virtual first cylinder has to be large enough that the first shaft can be plugged into the first shaft socket, i. e. slightly larger than a maximum radius of the first shaft. For the purpose of centering the first shaft to the main axis by means of the first shaft guide, the radius of the first cylinder must not be much larger than the maximum radius of the first shaft.
[0041] If the coupler according to the invention, in the first shaft socket, shall be able to compensate for angle errors and eccentricities of the first shaft with regard to the main axis, the radius of the first cylinder has even to be significantly larger than the maximum radius of the first shaft. The outer shaft guide ensures that the first shaft is at least pre-aligned with regard to the coupler body before it encounters the leaf springs. In this way it can be avoided that a miss-aligned first shaft damages the leaf springs when plugged-in.
[0042] At its inner axial end behind the leaf springs, the first shaft socket may have an inner shaft guide with a second cylindrical surface, the second cylindrical surface being at least a part of a surface of a second virtual cylinder coaxially arranged with regard to the main axis, whose radius is smaller than the distance of the first leaf spring to the main axis. This second inner shaft guide may receive a cylindrical appendix of the first shaft, which is reduced in radius, to further align the first shaft with regard to the main axis of the coupler body. With a tight fitting of the outer and inner shaft guides with regard to the first shaft, a coaxial alignment of the first shaft with regard to the main axis can be provided for. It is to understood that the coupler according to the invention then has to have additional features if eccentricities and angle errors of the first shaft shall be compensated for.
[0043] A second shaft coaxially arranged with regard to the main axis may be directly formed at the coupler body. Alternatively, a second shaft socket for a second shaft corresponding to the first shaft socket for the first shaft can be formed at the coupler body. In a projection along the main axis, the first leaf spring of the first shaft socket and a first leaf spring of the second shaft socket may then be parallel or orthogonal to one another, although, in principle, any angles between the two leaf springs are possible. The arrangements of the first leaf springs of the first and the second shaft sockets may be adapted to first and second shafts which are equal or unequalparticular with regard to their radiuses, i. e. the first leaf springs of the first and the second shaft sockets may have same or different distances to the main axis. Any inner and/or outer shaft guides may also be adapted to equal or unequal first and second shafts.
[0044] To compensate for angle errors of the first shaft with regard to a second shaft formed at the coupler body or to a second shaft inserted into a second shaft socket of the coupler body, the coupler body may have a biaxial joint, particularly a biaxial solid-body joint, between the first shaft socket and the second shaft or the second shaft socket.
[0045] In a coupling device according to the present invention comprising the coupler according to the present invention and a first shaft having a first shaft axis, which is plugged in or to be plugged into the first shaft socket, the circumferential surface of the first shaft has at least a first flattening extending tangentially to a second virtual arc of a circle around the first shaft axis and along the first shaft axis, against which the first leaf spring of the first shaft socket at least locally abuts at an elastic pre-stress. If this flattening of the first shaft is symmetric to a mirror plane through which the main axis runs, and if the first leaf spring with plugged-in first shaft is also mirror-symmetrically arranged and configured with regard to this mirror plane, the maximum torque transferable by the coupling device according to the invention is equal in both rotational directions about the main axis. However, if, for example, the at least one first flattening of the first shaft is provided with different increases or gradients of the distance to the first shaft axis in the two rotational directions about the first shaft axis, different maximum torques in the two rotational directions can also be realized. Thus, the coupling device according to the invention can be configured for transferring an at least twice as high torque in the one rotational direction than in the other rotational direction. In this way, for example, a rotational stop for the second shaft may be approached at a limited torque of a drive comprising the first shaft in the one rotational direction, whereas a higher torque can be transferred for removing the second shaft from the rotational stop in the other rotational direction.
[0046] As already mentioned further above, a maximum radius of the first shaft may be gradually reduced in an end region towards a free axial end of the first shaft to facilitate the insertion of the first shaft into the first shaft socket with elastic radial deflection of the first leaf spring.
[0047] The coupling device according to the invention may in a simple way be configured such that the first shaft plugged in the first shaft socket is securely but nevertheless releasable held within the first shaft socket in the axial direction of the main axis. If, for this purpose, the first flattening towards the free axial end of the first shaft is delimited by a snap-fit flange in which the radius of the first shaft increases beyond the distance of the first flattening to the first shaft axis, the first leaf spring snapping-in behind the snap-fit flange when plugging the first shaft into the first shaft socket, the leaf spring also serves as a snap-fit element for axially securing the first shaft. Further, securing the first shaft in the first shaft socket by means of the leaf spring may be released by means of a relative rotation of the first shaft with regard to the coupler until the leaf spring abuts against the first shaft outside the flattening and is thus no longer stopped by the snap-fit flange. The snap-fit flange may be formed in that the first flattening is worked into a cylindrical part of the first shaft, at a distance to an end of this cylindrical part pointing towards the free axial end of the first shaft.
[0048] Referring now in greater detail to the drawings, the coupling device 1 depicted in
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[0055] The cross section according to
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[0060] The coupler connection depicted in
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[0062] The coupler according to the invention is suitable for radiuses of the first shaft 13 and correspondingly also of the second shaft 12 starting from 0.5 mm. The coupler according to the invention is suitable for any combination of drive source and driven acceptor, for example in a generator, a winch, an automation technology and in robots. The maximum dimensions of the coupler 2 are typically 5 to 10 times as large as the radius of the first shaft or the second shaft depending on which of these two shafts has the larger radius. For forming the coupler body 3 with the leaf springs 4, 5, 14, 15 in one piece, the coupler 2 may be made by material adding techniques, like in a mold or a forming tool, or by material removing techniques starting from a massive blank. A multi-part design with leaf springs 4, 5, 14, 15 rigidly mounted to the coupler body 3 is also possible.
[0063] Many variations and modifications may be made to the preferred embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of the present invention, as defined by the following claims.