WO2017167936A1

WO2017167936A1 - Mechanical coupling

Info

Publication number: WO2017167936A1
Application number: PCT/EP2017/057636
Authority: WO
Inventors: Paul Richards; Jean-Pierre HAGEN
Original assignee: Renold Plc
Priority date: 2016-04-01
Filing date: 2017-03-30
Publication date: 2017-10-05
Also published as: DE202016101746U1

Abstract

The application relates to a mechanical coupling for transmission of a rotational movement around an axis of rotation (15). The coupling comprises two separate, identically shaped coupling parts (11, 12), wherein at least one of the coupling parts (11, 12) can be fixed to a torque transmitting element. Each of the coupling parts has at least one protruding element (13, 14) that fits into a recess (17, 18) of the other coupling part (11, 12), and at least one elastic element (26, 28) is provided between the wall (20, 21) of at least one recess (26, 28) and a protruding element (13, 14) that fits into the recess. Further, at least one of the elastic elements (26, 28) comprises at least two legs (22, 23), wherein at least two legs fit on different sides of the protruding element (13, 14) between the protruding element and the side walls (20, 21) of the recess and wherein the two legs (22, 23) are connected by at least one bottom part (24).

Description

Mechanical Coupling

The invention lies in the field of mechanical engineering and may be used in the field of any mechanical application where a rotational movement has to be transferred. The transfer of a rotational movement can be provided by a coupling. Couplings are generally used to transmit rotational motion from one system to another translating both rotational speed and torque in the process. The combination of limitations on speed and torque results in a power curve which defines the rating of a particular coupling over a range of speeds.

Important to the performance of a coupling is the ability to accommodate misalignment, which inevitably occurs when two pieces of machinery and corresponding drive shafts are brought together. The coupling acts as a means of relieving the repeated cyclical loads induced by such misalignment. The misalignment can take the form of axial displacement, where the two shafts are perfectly parallel but the centers are offset relative to each other, or

angular displacement, where the line of the intersection of the axes of the mating shafts forms an angle at the center of the coupling greater than zero degrees. In practice, the misalignment in an installation will consist of both elements.

Typically, a conformable element or elastomeric separator is employed between the halves or parts of a coupling to manage the misalignment but also to accommodate any vibrational torque transmitted from the driver to the driven part of the system.

From the prior art, couplings are known that provide elastic parts that can take care of lateral and/or angular misalignments and damp vibrations.

Since couplings are often used to connect large pieces which need to have high uptime and are difficult to move once installed, it is also a beneficial feature to adjust the coupling in situ.

It is also an object of the invention that the design of the coupling has a minimum number of different components in order to reduce complexity and keep cost to a minimum.

The management of torsional vibrations and other forces imposed by the system is one key to achieving a high power rating, and the ability to easily adjust the performance of the coupling by changing the stiffness and hence natural frequency of the conformable element array would offer a significant advantage.

Further, one object of this invention is the combination of low component count, easy maintenance and adjustable performance.

At least one object is achieved by the features of the invention that are incorporated in claim 1. Further advantageous implementations of the invention are described in claims 2 to 16.

As a matter of consequence, the invention refers to a mechanical coupling for transmission of a rotational movement around an axis of rotation with two separate, identically shaped coupling parts (coupling halves), wherein at least one of the coupling parts can be fixed to a torque transmitting element, wherein each of the coupling parts has at least one protruding element that fits into a recess of the other coupling part, wherein at least one elastic element is provided between the wall of at least one recess and a protruding element that fits into the recess. Further, at least one of the elastic elements comprises at least two legs, wherein at least two legs fit on different sides of the protruding element between the protruding element and the side walls of the recess and wherein the two legs are connected by at least one bottom part.

The protruding element(s) may protrude particularly in a direction parallel to the axis of rotation and the protruding elements may be claws. The two coupling parts (coupling halves) will usually be located one opposite to the other.

The structure of the elastic element(s) allows easy mounting of the elastic elements in each part of the coupling. An elastic element may be mounted in situ in a recess of one of the coupling parts and after that, a protruding element or a claw of the other coupling part can be inserted into the recess and between the legs of the elastic element. The coupling parts may be cylindrical and the recesses in the coupling parts may be open to a

circumferential, cylindrical outer surface of the respective coupling part, but do not necessarily have to be open. The protruding elements may be inserted into the respective recesses in axial direction.

The side walls of a recess are the two walls or wall parts that in a cross sectional view perpendicular to the axis of rotation define the two limits or outer ends of the azimuthal extension of the recess or, in other words, the two extreme ends of the recess in circumferential direction. If a protruding element or claw of one coupling part is positioned in a recess of the other coupling part, the protruding element or claw may, depending on the direction of the rotation, press against one or the other side wall of the recess in azimuthal/circumferential direction. The elastic elements can be simply described by a cross sectional view perpendicular to the axis of rotation. In this cross sectional view, an elastic element may have, for example, the form of a "u" or "v", with two legs that are linked by a basis or bottom or, in the case of a "v", immediately to each other. Along the direction that is perpendicular to the cross section, the form of the cross section may be variable or constant, but the structure of the cross sectional form will be unchanged from the first end to the second end of an elastic element along the axis of rotation. In the mounted state of a coupling, the two legs of an elastic element are positioned next to two sides of a protruding element or claw that is inserted in a recess wherein the two sides of the protruding element or claw are opposite to each other and form the extreme ends of the claw in circumferential direction.

The bottom part of the elastic element may be as long as the legs or shorter. The bottom part may consist of more than one bridge between the legs of the elastic element.

The bottom part may consist of the same material as the legs or of a different material. The bottom part may, for example, consist of a material with a higher stiffness than the legs.

An elastic element may be positioned in a recess of a coupling part with th bottom part at the bottom of the recess, at the ends of the legs that are closest to the axis of rotation.

The legs of the elastic element in a cross sectional view perpendicular to the axis of rotation may typically be oriented with their longest extension parallel to a radial direction with regard to the axis of rotation. In this case, the bottom part of an elastic element points to the axis of rotation, i.e., the bottom part is the part of an elastic element that is positioned closest to the axis of rotation.

On the other hand, the elastic elements could also be positioned in the recesses in a way that they would point radially outwardly and be the part of the elastic elements that is closest to the circumferential surface of the respective coupling part. The legs of the elastic elements are positioned between the side walls of a recess and a claw. The legs of the elastic element, through the elasticity of their material, damp vibrations and dynamic changes of torque and the pressure that is transferred between the protruding element or claw and the side walls of the recess.

The fact that in each elastic element two legs are fixed to each other and that there is a bottom part of the elastic element provides a simple and efficient mounting method, a reliable mounting of the elastic elements and a high stability of the position of each elastic element, even when subject to huge forces.

If the recesses are open to the circumferential cylindrical surface of the coupling parts, the elastic elements may be mounted and/or replaced in situ from the circumferential side of the coupling parts, even if a protruding element or a claw is still partially inside the recess.

A particular embodiment of the invention may provide that all elastic elements have identical shape. In this case, sourcing and storage of the elastic elements is simple and cost efficient, and it is easy to replace elastic elements.

By the use of identically shaped elastic elements, a symmetrical structure of the two coupling parts can be achieved. Also, the total number of different parts of the coupling is reduced. From the explanation above, it should also have become clear that one embodiment may be defined by the fact that the at least one elastic element in a cross sectional view has a U- or V-shape, wherein each of the legs of the U or V forms one of the legs of the elastic element and wherein the two legs are connected by a bottom part.

A further aspect of the invention may be that each of the elastic elements is inserted by form fit into a recess and/or that each of the elastic elements is inserted by force fit into a recess.

By form-fitting or force-fitting, it can be made sure that the elastic elements remain in their position in the recesses without any further interaction and that the claw or the protruding elements or claws may be inserted into the recess or recesses without a risk to lose the elastic elements or to displace them. The position of each elastic element in a recess may be defined by the form fit. A form fit may be based on a snap-in mechanism and/or on an extension of the elastic element that fits into a special opening in or next to a recess.

For example, a particular embodiment of the invention may provide that each of the recesses has an undercut in which an elastic element can be inserted with a positive locking or by a force-locked connection.

A further aspect of the invention may for example provide that each of the elastic elements has a snap-in connection with a recess.

It may further be provided that in a cross sectional view, the legs of the elastic elements protrude from the bottom parts in a radial direction away from the axis of rotation. The cross section is meant to be perpendicular to the axis of rotation of the coupling. The legs of the elastic elements are then pressed between a protruding element or a claw of one coupling part and the side walls of a recess of the other coupling part. A tendency of the coupling parts to squeeze the legs of the elastic elements towards a radially outward position— radially out of the coupling parts— is prevented by the fact that the legs of the elastic elements are linked and fixed to the bottom part of the respective elastic element which holds the two legs and fixes them in a radial direction.

A further aspect of the invention may be, as discussed already above, that in a cross sectional view perpendicular to the axis of rotation, the legs of the elastic elements protrude from the bottom parts in a radial direction towards the axis of rotation.

Another embodiment may provide that in a cross sectional view, the legs of the elastic elements are formed with a convex surface on at least one side. A particular embodiment of the invention may provide that in a cross sectional view, the legs of the elastic elements are formed with a concave surface on at least one side.

By a convex or a concave surface on at least one side the form of the protruding elements or claw(s) and/or the outer form of the recess in the coupling part may be created in a respective way to avoid any force that squeezes the material of the elastic element in a radial direction out of the intermediate space between the protruding element or claw and the walls of a recess.

It may further be provided that the elastic elements are insertable and/or removable from the coupling in situ while at least one protruding element or claw of one coupling part is at least partially protruding into one recess of the other coupling part.

Another aspect may provide that all elastic elements are of identical shape and have the same elastic modulus.

This reduces the number of different parts that have to be managed with regard to mounting and repair or maintenance.

A further aspect may provide that all elastic elements are of identical shape, wherein a first group of elastic elements has a first elastic modulus and a second group has a second elastic modulus different from the first elastic modulus. By this implementation, different average stiffnesses of the elastic elements may be produced. The torque is transferred by the coupling overall, i.e. by addition of the effects of all protruding elements or claws and recesses that are interacting and the respective elastic elements that transfer the forces in each recess.

By using different elastic element, an average overall stiffness of the coupling may be established. The number of stiffer and less stiff elastic elements may be varied according to a target overall stiffness. Another particular embodiment may provide that the elastic elements are encoded differently according to their elastic modulus.

The encoding may include different geometrical shapes or sizes or other qualities by which different elastic elements may be distinguished, such as, for example, magnetic/non magnetic or having a recess/opening at a certain location or not.

Still another embodiment may provide that elastic elements of the first group are colored differently from the elastic elements of the second group. In this case, the elastic elements of the two groups may be easily distinguished by assembly personnel so that a target configuration with different elastic elements may reliably be achieved.

Below, examples of the invention will be explained with reference to figures of a drawing. The invention, however, is not restricted in any way to the examples shown or to the examples and features that are described.

Therein

Figures show couplings that are known from the prior art,

Figure 4 shows a perspective view of one coupling part,

Figure 5 shows a perspective view of an elastic element,

Figure 6 shows in a perspective view two coupling parts of a coupling with elastic elements in a state where the two coupling parts are separated partially from each other,

Figure 7 shows in a perspective view the coupling wherein the

coupling parts are put together and the coupling is able transmit torque,

Figure 8 shows in a diagram the relation between torque that may be transferred by a coupling and the main OD for different types of couplings including the coupling according to the invention, shows in a diagram the relation between torque that may be transferred by a coupling and the bore size for different types of couplings including the coupling according to the invention,

Figure 10 shows in a diagram the relation between possible speed of rotation for which torque may be transferred by a coupling and the main OD for different types of couplings including the coupling according to the invention, and

Figure 11 shows a cross section of an elastic element with three

Figure 1 shows a known type of a coupling, in which two coupling parts 1, 2 are coupled by screws that hold the coupling parts together. In at least one the coupling parts, the respective bores through which the screws protrude provide sleeves 3 of elastic material. By the elastic material, the contact between the screws and one coupling part is damped. Therefore, the two coupling parts are fixed to one another elastically.

The same holds for the coupling type that is shown in Figure 2. An elastic transfer plate 4 is inserted between the two coupling parts 5, 6 and each coupling part is fixed to the elastic plate separately.

Figure 3 shows a coupling type with two identically shaped coupling parts 7, 8, wherein each of the coupling parts shows claws 9 that protrude in an axial direction into recesses of the other coupling part.

One single elastic element 10 is provided that has a ring shape and provides noses that damp the contact between the two main coupling parts. One disadvantage of this coupling is that the elastic element can only be mounted or changed when the two main coupling parts are completely separated from each other. Figure 4 shows in a perspective view one main coupling part 11 of a coupling according to the invention.

The coupling part (coupling half) 11 shows a cylindrical symmetry around the axis of rotation 15 and six claws 13, 14 that protrude in an axial direction parallel to the axis of rotation 15 towards the other main coupling part (not shown). In the center of the coupling part 11, a central bore 16 is provided where the coupling part can be coupled with an axle (not shown). Between the six claws 13, 14, six recesses 17, 18 are formed that are all shaped identical to each other. The six recesses are provided to receive the claws from the second coupling part (not shown in Figure 4).

The recesses 17, 18 have a concave bottom 19, but in other implementations of the invention the bottoms might as well have a flat or convex profile.

The recesses have a partially cylindrical form with concave side walls 20, 21 and with an undercut that is perfectly seen from an axial view parallel to the axis of rotation 15. Thereby, a cylindrical or partially cylindrical object, for example an elastic element 26, 28, may be form-fitted into each of the recesses. If the side walls of the elastic element have a cylindrical form, they fit into the concave cylindrical side walls of the recesses and are held back in radial direction by the undercut of the side walls of the recesses. Other appropriate forms of the recesses and the elastic elements are possible as well.

Figure 5 shows in a perspective view an elastic element 26 in "U" shape with two legs 22, 23 and a bottom part 24, wherein the two legs 22, 23 form the legs of the "U" and the bottom part 24 forms the connection between the legs. The "U"-shape extends in a direction 25 parallel to the axis of rotation (in a mounted state) along the length of the elastic element. The elastic elements 26, 28 may comprise or consist of an elastomer, a polymer, composite material or any other material capable of accommodating the transmitted torque. Instead of the two legs, the elastic element may as well comprise three or more legs that may be accommodated in one or more adjacent recesses of a coupling part. Figure 11 shows a cross section of an elastic element with three legs. The individual legs need not necessarily have the same shape or length.

The elastic element 26 has a snap-in element 27 that is connected to the bottom part 24 and protrudes from the bottom part in an axial direction 25.

Each of the two legs 22, 23 of the elastic element in a cross sectional view has two (inner and outer) convex sides22a, 22b. The outer convex sides 22b of the legs fit to the concave side walls 20, 21 of the recesses of the coupling part shown in Figure 4. All side walls and the bottom outer side of the elastic element may also be flat (not shown).

Figure 6 shows a perspective view of a coupling according to the invention with two main coupling partsll, 12 and respective elastic elements 26, 28 in front of the recesses of the coupling parts.

The two main coupling parts are shown in this figure in an axially separated position where the claws of one coupling part are not yet inserted in the recesses of the other coupling part.

The two coupling parts have identical shape and are put together with an angular shift of 360/12, i.e. 30 degrees, in order to fit each claw in the recess between two respective claws on the other side of the coupling. This angular shift also generates a 30 degree shift of the elastic elements 26, 28 in the recesses of one coupling part relative to the elastic elements in the recesses of the other coupling part. The elastic elements in each of the two coupling parts are thus shifted, but overlapping with regard to the angular position of the elastic elements in the respective other coupling part.

In the position shown in Figure 6, all or at least some of the elastic elements 26, 28 may be mounted, removed from the recesses, or replaced. Their snap- in elements 27 are, in a mounted state, inserted in axial extensions of the recesses; these extensions are open to the circumferential surface of the coupling parts. In the mounted state, the elastic elements are not only held in position by the form fit of the elastic elements in the recesses, but also by the snap-in elements. The legs 22, 23 of the elastic elements are then positioned between the claws 13, 14 and the side walls 20, 21 of the recesses 17, 18. The bottom parts 24 of the elastic elements are positioned between the claws 13, 14 and the bottom parts 19 of the recesses, on the radially inner side the claws.

Figure 7 shows a position in which the two main coupling parts 11, 12 are put together and the coupling is in a working state where it is fully capable of transmitting torque and rotational speed.

The claws 13, 14 of each coupling part 11, 12 (coupling half) are fully inserted in the respective recesses of the other coupling part. The elastic elements that are inserted in the recesses of one coupling part are axially close to the elastic elements inserted in the recesses of the other coupling part, wherein the elastic elements of the different coupling parts may be, but do not have to be, in touch with each other.

Since the 'U' shaped elements have a natural separation line between the two halves of the coupling, there can also be some accommodation of axial displacement if needed.

The elastic elements 26, 28 may all be of the same type, or every second or third element in circumferential direction may be of a different type, for example made of a different material and/or with a different stiffness / elastic modulus. Elements of different type may be marked appropriately or be of different color so that they may be selected for a specific application and applied.

The diagram of Figure 8 shows curves that reflect the relation of the main OD, that is, the overall outer diameter of the coupling, and the torque that can be transferred by different coupling types. It becomes clear that the coupling according to this invention (curve 29) has the ability to transfer considerable torque even with a small main OD, compared with other coupling types that are represented in the other curves. Figure 9 shows in a diagram the relation of the bore size of a coupling, that is, the maximum shaft diameter that can be accommodated, and the torque that can be transferred by different coupling types. It becomes clear that the coupling according to this invention (curve 30) has the ability to work with a big bore size and transfer high torque, as compared to some other coupling types represented in the remaining curves of Figure 9.

Figure 10 shows the relation between the speed of rotation that can be transferred by different types of couplings and the main OD. It emerges that the coupling according to this invention (curve 31) has the ability to transfer torque even at high rotation speed and with a bigger main OD than other coupling types.

Claims

Renold Pic. 177PCT 0837 Claims

Mechanical coupling for transmission of a rotational movement around an axis of rotation (15) with two separate, identically shaped coupling parts (11, 12), wherein at least one of the coupling parts (11, 12) can be fixed to a torque transmitting element,

wherein each of the coupling parts has at least one protruding element (13, 14) that fits into a recess (17, 18) of the other coupling part (11, 12), wherein at least one elastic element (26, 28) is provided between the wall (20, 21) of at least one recess (26, 28) and a protruding element (13, 14) that fits into the recess,

characterized in that at least one of the elastic elements (26, 28) comprises at least two legs (22, 23), wherein at least two legs fit on different sides of the protruding element (13, 14) between the protruding element and the side walls (20, 21) of the recess and wherein the two legs (22, 23) are connected by at least one bottom part (24).

Coupling according to claim 1, characterized in that all elastic elements (26, 28) have an identical shape.

Coupling according to claim 1 or 2, characterized in that the at least one elastic element (26, 28) in a cross sectional view has a U- or V- shape, wherein each of the legs (22, 23) of the U or V forms one of the legs of the elastic element and wherein the two legs are connected by a bottom part (24).

Coupling according to claim 1, 2 or 3, characterized in that each of the elastic elements (26, 28) is form-fitted into a recess (17, 18).

5. Coupling according to claim 1, 2, 3 or 4, characterized in that each of the elastic elements (26, 28) is force-fitted into a recess (17, 18).

6. Coupling according to claim 1, 2, 3, 4 or 5, characterized in that each of the recesses (17, 18) has an undercut in which an elastic element (26, 28) can be inserted with a positive locking or by a force-locked connection.

7. Coupling according to claim 1, 2, 3, 4, 5 or 6, characterized in that each of the elastic elements (26, 28) has a snap-in connection (27) with a recess.

8. Coupling according to one of the claims 1 to 7, characterized in that in a cross sectional view, the legs (22, 23) of the elastic elements (26, 28) protrude from the bottom parts (24) in a radial direction away from the axis of rotation (15).

9. Coupling according to one of the claims 1 to 7, characterized in that in a cross sectional view, the legs (22, 23) of the elastic elements (26, 28) protrude from the bottom parts (24) in a radial direction towards the axis of rotation (15).

10. Coupling according to one of the claims 1 to 9, characterized in that in a cross sectional view, the legs (22, 23) of the elastic elements (26, 28) are formed convex on at least one side (22b).

11. Coupling according to one of the claims 1 to 10, characterized in that in a cross sectional view, the legs (22, 23) of the elastic elements are formed concave on at least one side.

12. Coupling according to one of the claims 1 to 11, characterized in that the elastic elements (26, 28) are insertable and/or removable from the coupling in situ and/or while at least one protruding element (13, 14) of one coupling part (11, 12) is at least partially protruding into one recess (17, 18) of the other coupling part.

13. Coupling according to one of the claims 1 to 12, characterized in that all elastic elements (26, 28) are of identical shape and have the same elastic module.

14. Coupling according to one of the claims 1 to 12, characterized in that all elastic elements (26, 28) are of identical shape wherein a first group of elastic elements has a first elastic modulus and a second group has a second elastic modulus different from the first elastic modulus.

15. Coupling according to claim 14, characterized in that the elastic

elements (26, 28) are encoded differently according to their elastic modulus.

16. Coupling according to claim 14, characterized in that elastic elements (26, 28) of the first group are colored differently from the elastic elements of the second group.