NL2034985B1 - Magnetic coupling assembly - Google Patents

Abstract

The present disclosure relates to a magnetic coupling assembly for coupling of a first rotary shaft and a second rotary shaft. The magnetic coupling assembly comprises: - a first rotary hub connectable to the first shaft; - a second rotary hub connectable to the second shaft; - a magnet rotor comprising a set of permanent magnets, the central magnet rotor coupled to the first rotary hub and arranged to co-rotate with the first rotary hub); - an induction rotor coupled to the second rotary hub and arranged to co-rotate with the second rotary hub); and - an temperature indication unit that is provided on the induction rotor, the temperature indication unit comprising: o a housing provided with a chamber at a first end of the housing, the chamber being at least partially in contact with the induction rotor, wherein the chamber comprises a material that is solid under a predetermined temperature at atmospheric conditions; and o a sensing element provided in the housing, wherein the sensing element extends into the chamber, and wherein the temperature indication unit has a normal state and an warning state, wherein in the normal state the material secures a securing end of the sensing element such that the sensing element is positioned substantially inside the housing, and wherein in the warning state the sensing element extends outside the second end of the housing, and wherein the sensing element is movable outside the housing by melting of the material due to the heating of the chamber, thereby moving the temperature indication unit from the normal state to the warning state.

Description

MAGNETIC COUPLING ASSEMBLY

The present disclosure relates to a magnetic coupling assembly for coupling of a first rotary shaft and a second rotary shaft.

Magnetic couplings are known. A magnetic coupling is a coupling between two shafts that makes use of a magnetic field. One shaft can be coupled to a magnet rotor, while the other shaft can be coupled to an induction rotor. The magnet rotor comprises permanent magnets that are magnetically coupled to the induction rotor. In this way the two shafts can be coupled with a physical separation. The torque of one of the shafts can be effectively transferred to the other shaft.

This allows for a coupling that reduces wear.

A problem of magnetic induction couplings is that the temperature of the induction rotor can become relatively high. This high temperature is caused by the current that is created in the induction rotor due to the changing magnetic field. The magnetic field changes due to the slip of the magnet rotor and the induction rotor. This high temperature can cause overheating of the magnetic coupling, which can damage parts of the magnetic coupling, or can even lead to a fire.

It is an object of the present invention convention to obviate or at least reduce one or more of the above-mentioned problems. In particular, it is an object of the present disclosure to provide magnetic coupling which could prevent overheating.

The object is achieved by a magnetic coupling assembly for coupling of a first rotary shaft and a second rotary shaft, the magnetic coupling assembly comprising: - a first rotary hub connectable to the first shaft; - a second rotary hub connectable to the second shaft; - a magnet rotor comprising a set of permanent magnets, the central magnet rotor coupled to the first rotary hub and arranged to co-rotate with the first rotary hub; - an induction rotor directly or indirectly coupled to the second rotary hub and arranged to co-rotate with the second rotary hub; and - a temperature indication unit configured to detect a predetermined temperature of at least a part of the induction rotor, the temperature indication unit comprising: - a housing comprising a chamber at a first end of the housing, the chamber being atleast partially in direct or indirect thermal contact with the induction rotor; - a sensing element arranged in the housing and having a securing end extending into the chamber, wherein the sensing element is movable in the housing between a first position representative of a normal state and a second position representative of a warning state; - retainer material arranged inside the chamber of the housing. wherein the retainer material is solid under a predetermined temperature at atmospheric conditions and melts above the predetermined temperature;

wherein at temperatures in the chamber below the predetermined temperature the retainer material secures the securing end of the sensing element so as to retain the sensing element in the first position and at temperatures at or above the predetermined temperature the retainer material allows the sensing element to move from the first position to the second position.

The sensing element is movable from the first position to the second position by melting of the retainer material due to heating of the chamber.

The retainer material in the chamber is selected to melt at a preselected temperature, for instance a critical temperature like the maximum allowable temperature in the magnetic coupling.

When the temperature of the induction rotor reaches the maximum allowable temperature, the material will melt. This removes the grip of the material on the securing end of the sensing element, thereby allowing movement of the sensing element from the normal state to the warning state. In the warning state the sensing element extends out of the housing or to a predetermined position. The part of the sensing element extending out of the housing or in its predetermined position can be detected by a detector, such as a proximity sensor. Therefore, sensing element provides an effective way of providing a signal that the temperature of the induction rotor is too high, i.e. above the preselected temperature. Adequate measures, such as slowing down of the shaft which drives the magnetic coupling, or applying cooling techniques to the magnetic coupling assembly, can be taken based on the sensing element extending out of the housing.

The housing may be formed in or mounted to the induction rotor or a main rotor (to which the induction rotor is coupled). The housing may be in physical, direct contact with the front plate, or directly to the backplate /not to the front plate, or in physical, direct contact with the main rotor (and not to the back plate and front plate), or physical, direct contact with an additional element of thermally conductive material placed between the induction rotor / main rotor and the housing.

Important here is that heat may be conducted from the induction plate (being the primary source of heat) to the chamber of the housing. wherein the retainer material is situated.

Imminent overheating can now be detected by checking the position of the sensing element. This can be done visually by an operator looking at the position (or a change of position) of the sensing element during operation of the coupling assembly, i.e. while the induction rotor is rotating or temporarily stopped or can be done using one or more sensors positioned at a small distance from the rotating rotors, as will be explained later. The sensing element can also cause an acoustic signal, for instance a sound signal generated by the sensing element after having changed its position. For instance, the sensing element may generate vibrations in the air surrounding the assembly during rotation of the rotors causing an audible warning signal. Similarly, the sensing element in its warning position may be caused to touch a stationary element (for instance a secondary mechanism located on the body (housing or support) of the magnetic coupling assembly) which can be a switch.

In an embodiment the housing and sensing element are oriented relative to the induction rotor to cause rotation of the induction rotor to move the sensing element from the first to the second position. As a result of mass inertia of the sensing element the rotation of the rotors will cause the sensing element to be moved radially outward when the sensing element cannot be retained anymore by the retaining material. Further means for moving the sensing element can be dispensed with. An embodiment wherein the effect of mass inertia is sufficient for moving the sensing element is when the sensing element in the housing extends in a radial direction. This may be a full radial direction or may mean that the sensing element extends in an oblique orientation so that it extends in a direction having both a radial component and a axial component. The inertial force (i.e. the centrifugal force) of the mass of the sensing element in the rotating induction rotor then is the (primary) cause of movement of the sensing element from the first to the second position, once the melting retainer material can no longer retain the securing end of the sensing element in the chamber of the housing.

In further embodiments the assembly comprises a biasing element, the biasing element being configured to urge the sensing element to move from the first to the second position. The biasing element is able to urge the sensing element from the first to the second position once the retainer material has melted to a sufficient extent.

The biasing element may be a resilient element arranged inside the housing, for instance a spring, especially a coil spring arranged around the sensing element.

In embodiments of the present disclosure the temperature detection unit is configured so that in the first position the sensing element is positioned substantially inside the housing while in the second position one end of the sensing element extends outside the housing. The second position corresponding to the warning state can be detected by monitoring whether or not the sensing element is projecting from the housing. In other embodiments the temperature indication unit is configured so that in the first position one end of the sensing element is positioned to extend outside the housing while in the first position the sensing element is positioned substantially inside the housing. The second position corresponding to the warning state can be detected by monitoring whether or not the sensing element is retracted into the housing.

In embodiments of the present disclosure the sensing element is an element or body, for instance an elongated element such as a pin, arranged in the housing to be movable in at least one of an axial direction, a radial direction, and a circumferential direction.

More than one temperature detections units may be provided on the same magnetic coupling assembly, for instance to detect different levels of overheating (for instance, a limited overheating which may only be detrimental to the lifespan of the coupling and a full overheating which may cause a dangerous situation). For instance, in a further embodiment, the assembly comprises a first temperature detection unit having retainer material with a first value of the predetermined temperature and a second temperature detection unit having retainer material with a second value of the predetermined temperature, wherein the second value is higher than the first value.

As mentioned above, the chamber may be at least partially in direct or indirect contact with the induction rotor. This can for example be achieved by at least one of the walls of the chamber being in physical contact with the induction rotor. Preferably, the chamber comprises a top wall positioned between the first and second end of the housing. The top wall may comprise a through- hole through which the sensing element can be positioned.

Any material that is solid under the maximum allowable temperature and liquid above the maximum allowable temperature is suitable for the present disclosure. The maximum allowable temperature can also be denoted as an upper threshold temperature. The material can for example be a metal, such as zinc or aluminum, or a plastic, such as polypropylene (PP), polyethylene (PE) or polyvinyl chloride (PVC), but preferably a fusible alloy.

Preferably. the second end of the housing comprises an opening through which the sensing element can extend outside the housing.

In an embodiment the sensing element is a pin that extends from its securing end in the chamber, further comprising a biasing element like a tensioning element or resilient element, that biases the sensing element to the second position.

The pin is an elongated element that extends from the first end of the housing to the second end of the housing. The biasing element is arranged in the housing such that the resilient element biases the pin towards the second end, and thus to outside the housing. The resilient element ensures that the pin will extend outside the housing when the material has melted. This improves the reliability of the temperature indication unit.

In an embodiment the pin comprises a abutment element, wherein the resilient element extends between a top wall of the chamber and the abutment element.

The resilient element can with a first end be arranged on the top wall of the chamber and with the second be arranged on the abutment element of the pin. The abutment element of the pin is positioned between the top wall of the chamber and the second end of the housing. This configuration provides an etfective temperature indication unit that is easy to manufacture.

In an embodiment the securing end of the sensing element is provided with ridges. The ridges provide an additional surface to which the material in the chamber can attach. This improves securing of the sensing element in the normal state. In this way, the likelihood of an erroneous warning signal that the induction rotor exceeds the maximum allowable temperature is reduced.

In an embodiment the biasing element comprises a spring. A spring may provide an effective bias of the sensing element towards outside the opening of the second end of the housing.

This ensures a reliable detection that the temperature of the induction rotor has exceeded the maximum allowable temperature.

In an embodiment the sensing element comprises a ball provided in the housing. The ball is, in the normal state, at least partially positioned in the chamber. Due to the rotation of the 5 induction rotor the ball will roll or move into the warning state when the material is melted, wherein the ball extends at least partly outside the second end of the housing.

In an embodiment the sensing element comprises a pin (cam) that is hingeably connected to the housing. The pin (cam) is, in the normal state, at least partially positioned in the chamber.

Due to the rotation of the induction rotor the pin (cam) will rotate into the warning state when the material is melted, wherein the pin (cam) extends at least partly outside the second end of the housing.

In an embodiment the interior of the housing has a substantially cylindrical shape. The cylindrical shape provides a solid construction for the housing. Alternatively, the cylindrical shape does not have any edges or corners, thereby providing a free movement of the sensing element through the housing when moving from the normal state to the warning state.

In an embodiment the movement of the sensing element is angular instead of linear.

The magnetic coupling assembly may further comprise a secondary mechanism, preferably arranged in a stationary manner relative to the rotating parts of the magnetic coupling assembly. positioned at a distance from the induction rotor such that the sensing element touches the secondary mechanism during rotation of the induction rotor only when the sensing element is in the second position. Touching of the secondary mechanism triggers the warning signal, for instance an acoustic signal caused by the sound generated every time the sensing element hits the secondary mechanism or an electric signal generated by an appropriate trigger circuit configured to generate the signal the when the sensing element for the first time comes into contact with (a movable part of) the secondary mechanism. For instance, the warning state may activate or move a secondary mechanism located on the body of the coupling assembly which can then be detected as the warning state.

In an embodiment the magnetic coupling assembly further comprises a sensor, preferably a proximity sensor, configured to be arranged at a distance from the induction rotor and being that is configured to detect if the sensing element has been moved from the first to the second position.

The sensor is generally a stationary sensor positioned at a short distance from the rotating induction rotor/main rotor so that each time the temperature detection unit passes by. the sensor may detect whether or not the sensing element is in the second position (that is representative of a warning state). The second position can be a position wherein the sensing element has either been displaced inwardly or been displaced outwardly.

For instance, the proximity sensor may be arranged such that it does not detect the sensing element when the sensing element is in the normal state, and it does detect the sensing element when the sensing element is in the warning state. For instance, the proximity sensor can effectively detect if the sensing element extends out of the second end of the housing or vice versa. This provides a reliable indication that the predefined temperature-like the maximum allowable temperature of the induction rotor is reached.

In an embodiment the magnetic coupling assembly comprises a main rotor that is coupled to the secondary rotary hub, wherein the induction rotor is indirectly connected to the second rotary hub via the main rotor. The induction rotor may comprise a plurality of induction rotor segments, each of the induction rotor segments being coupled to the main rotor via a segment coupling.

The magnetic force of the magnet rotor forces the induction rotor to co-rotate, thereby providing a coupling between the first and second rotary shaft. The induction rotor is configured to co-rotate with the magnet rotor.

Further advantages, features and details are elucidated on the basis of exemplifying embodiments thereof, wherein reference is made to the accompanying drawings, wherein: - figure 1 shows a side view of a first embodiment of a magnetic coupling assembly arranged between examples of a drive unit and a load unit; - figure 2 shows a side view of the first embodiment of the magnetic coupling assembly: - figures 3 and 4 show perspective views of the first embodiment of the magnetic coupling assembly; - figure 5 shows an exploded view of the first embodiment of the magnetic coupling assembly; - figures 6A and 6B show respectively a perspective side view and a top view of a pair of induction rotor segments forming a rotor segment; - figures 7-10 show perspective and side views of the assembly of the magnetic coupling assembly; - figures 11 shows a perspective view of the temperature detection unit in the normal state; - figure 12 shows a side view of the temperature detection unit in the normal state; - figures 13 shows a perspective view of the temperature detection unit in the extended state; - figure 14 shows a side view of the temperature detection unit in the extended state; - figure 15 shows a perspective view of a pair of induction rotor segments; - figure 16 shows a top view of a pair of induction rotor segments according to a further embodiment;

- figure 17 is a side view of a further embodiment of an induction plate of an induction rotor segment part of an inductor rotor; - figure 18 is a side view of a further embodiment of a magnetic coupling assembly; - figure 19 is a partly cut-away side view of a further embodiment of a magnetic coupling assembly having two parallel main rotors; - figure 20 is a more detailed side view of the embodiment of figure 19, just before an inductor segment is attached to a main rotor; - figure 21 is a side view of a further embodiment of a magnetic coupling assembly showing two main rotors between which a plurality of segments has been mounted wherein the spacers are configured to have an adjustable length; - figure 22 is a partly cut-away view of the embodiment of figure 21, showing one pair of induction rotor segment parts right before attachment to the main rotor(s) by sliding action; - figure 23 is a side view of an embodiment of the pair of induction rotor segment parts of figure 22; - figures 24A and 24B are cross-sections of the pair of induction rotor segment parts, respectively in a first position wherein the mutual distance between a back plate and a set of induction plates is relatively large and a second a position wherein the mutual distance between a back plate and a set of induction plates is relatively small; - figure 25 is a partly cut-away side view of a further embodiment of the magnetic coupling assembly, having adjustable spacers and an induction rotor at one side only (single arrangement); - figure 26 is a side view of the embodiment of figure 25; - figure 27 is a partly cut-away side view of a further embodiment of the magnetic coupling assembly, having adjustable spacers and an induction rotor at both sides of the magnet rotor; and - figure 28 is a side view of the embodiment of figure 27.

Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the disclosure can operate in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. The terms so used are interchangeable under appropriate circumstances and the embodiments of the disclosure described herein can operate in other orientations than described or illustrated herein.

As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible.

Referring to figures 1-6, a first exemplifying embodiment of a magnetic coupling assembly 2 arranged between a drive unit 7 and a load unit 3 is shown. The drive unit 7 may be any type of drive or drive motor, like an electric motor or a combustion engine, capable of causing a drive shaft 9 (herein also referred to as the second shaft) to rotate (denoted by Rp). The load unit 3 may be any type of load that is to rotatable driven by the drive unit 7. The load may be any type of machine like a fan, turbine, pump etc. having a load shaft 5 (herein also referred to as the first shaft) that is to be rotated (Ry) by drive shaft 9 of the drive unit 7.

The magnetic coupling assembly 2 comprises a least one (possibly two or more) first, generally disc-shaped, rotary element, herein referred to as a magnet rotor 8 (see the hatched part in figure 2), a second. for instance a generally disc-shaped element, herein referred to as a main rotor 26, a first rotary hub 4 mounted to (for instance using bolts 10) or integrally formed with the magnet rotor 8 and a second rotary hub 22 mounted to (for instance using bolts 28) or integrally formed with the main rotor 26. The first rotary hub 4 is configured to be releasably connected to the first (load) shaft 5 of the load unit 3 and second rotary hub 22 is configured to be releasably connected to the second (drive) shaft 9 of the drive unit 7. The first rotary hub 4 and the magnet rotor § belong to the load side of the magnetic coupling assembly 2 while the second rotary hub 22 and the main rotor 26 belong to the drive side of the magnetic coupling assembly.

In the embodiments described hereafter the main rotor 26 may have coupled thereto a separate induction rotor 32. However, in all of the embodiments described hereafter the combination of such mutually coupled inductor rotor 32 and main rotor 26 can also be embodied as an integrated rotor (i.e. the induction rotor and main rotor being combined into one single (induction) rotor.

In embodiments of the present disclosure the second (main) rotor 26 and the second rotary hub 22 (or first rotary hub 4) may be separate elements, while in other embodiments the second (main) rotor 26 and the secondary hub 22 are integrated and form a single integrated rotor-hub element. For instance, the rotary hub may be formed as a rotor.

The magnetic coupling assembly 2 is configured to cause the first (load) shaft 5 to co- rotate with the second (drive) shaft 9 using a magnetic type of coupling between the (inductor rotor coupled to the) main rotor 26 and magnet rotor 8. In principle no physical contact is present between the drive side and the load side of the magnetic coupling assembly 2. In other words, any torque provided by the drive unit 7 is transferred from the drive shaft to the load shaft using a magnetic field rather than a physical mechanical connection.

While the first hub 4 and second hub 9 are arranged to be mutually aligned, the magnetic coupling assembly 2 can be said to be rotatable relative to a common imaginary axis R (cf. figures 3 and 4). Furthermore, the rotation speed (i.e. the number of revolutions per unit of time) of the second (drive) shaft 9 may be the same as the rotation speed of the first (load) shaft 5 or may differ. Generally the rotation speed of the second (drive) shaft 9 is higher than the rotation speed of the first (load) shaft 5, according to a constant or adjustable speed ratio.

In order to connect the rotary hubs 4, 22 to the respective shafts 5, 9 the first rotary hub 4 may comprise a cylindrical opening 6 (figure 4) configured to receive therein an end of the first shaft 5 while the second rotary hub 22 may comprise a cylindrical opening 24 (figure 3) configured to receive therein an end of the second shaft 9.

Both the magnet rotor 8 and the main rotor 26 are optionally provided with cooling means, for instance one or more air openings 12 (for instance, six air openings) in the magnet rotor 8 and one or more air openings 30 in the main rotor 26. The air openings 20, 30 may be positioned at predefined radial distances relative to the imaginary rotation axis R. Other distributions of the air openings 20, 30 are possible as well. Furthermore, in the illustrated embodiments, openings 12 of magnet rotor 8 and openings 30 of main rotor 26 are provided at an equal distance to imaginary rotation axis R, such that openings 12 and openings 30 are positioned substantially in line when viewed in axial direction. The axial direction is in the illustrated embodiments parallel to the imaginary rotation axis R.

An inductor rotor 32 may be integrally formed with or mounted to the main rotor 26. In other embodiments, an inductor rotor 32 is removably coupled to the main rotor 26. Furthermore, the induction rotor 32 may be formed by one or more annular induction elements wherein at least one of the annular induction elements is attached (removably or permanently) to the main rotor 26.

In other embodiments, for instance in the illustrated embodiments, the induction rotor 32 is comprised of multiple induction rotor segments 34. In the embodiments shown in figures 1-10 and 15-16, the induction rotor 32 comprises a plurality of induction rotor segments, each induction rotor segment 34 being shaped as an annulus sector defined as an imaginary cut from an annulus, which is bordered by two straight lines from the center of the annulus (i.e. from the center corresponding to the location of the imaginary rotation axis R). In the shown embodiment the inductor rotor segments 34 are of equal shape and dimension (so that their fabrication may be standardized, which may reduce the overall costs of the inductor rotor 32). Furthermore, the inductor rotor segments 34 may be coupled one by one to the main rotor 26 (cf. figures 7-10) to form the induction rotor 32. This has a number of advantages in the sense of ease of fabrication, less precise machining of the individual components of the induction rotor, simplified balancing of the rotor(s) of the coupling assembly, and/or reduction of the total manufacturing and assembly costs. A further advantage may be the possibility to reduce particular types of hazard generally associated with the fabrication of magnetic couplings, as will be explained in connection with figures 7-10.

In the shown embodiments the number of induction rotor segments 34 is six. In other embodiments the shape and dimension may mutually vary and/or the number of segments may be larger or smaller.

In embodiments of the present disclosure, for instance in the embodiments shown in figures 5-10, each induction rotor segment 34 comprises a back plate 38 made of magnetizable material, for instance iron, while attached to the back plate 38 is a front (induction) plate or simply an induction plate 36, preferably made of a non-magnetizable material, for instance copper. In some embodiments, for instance in the embodiment of figures 15 and 16, an induction rotor segment 34 comprises a plurality of induction plates 36 (i.e. induction plates 36a, 36b, cf. figure 15-16), as will be explained later.

In embodiments of the present disclosure the inductor rotor 32 is located at one side of the magnetic coupling assembly (i.e. a so-called single inductor coupling), i.e. at one side of the magnet rotor 8, either at the side of the drive unit 7 or at the side of the load anit 3. However, in other embodiments the inductor rotor 32 is present at both sides. Furthermore, while in the embodiments shown in figures 1-10, the inductor rotor 32 is present at both sides of a single magnet rotor (a so-called dual inductor coupling), in other embodiments, for instance in the embodiment of a magnetic coupling assembly 51 of figure 18 (a so-called quad inductor coupling), two magnet rotors are provided and an inductor rotor 32 is present at both sides of each of the magnet rotors. The number of magnet rotors may even be larger than two and embodiments with a plurality of magnet rotors with each magnet rotor only having an associated inductor rotor present atone single side thereof are possible as well.

Furthermore, as shown in the figures, the inductor rotor 32 may be comprised of a number of induction rotor segments 34 wherein each induction rotor segments 34 comprises a pair 40 of induction rotor segment parts 40a, 40b, interconnected by one or more spacers 42.

Each pair 40 of induction rotor segment parts comprises a first induction rotor segment part 40a and a second induction rotor segment part 40b. A first induction rotor segment part 40a and a second induction rotor segment part 40b of a pair 40 are, seen in a direction parallel to the imaginary rotation axis R, attached to each other such that they remain spaced apart by use of one or more elongated spacers 42. The first induction rotor segment parts 40a are attached in such a manner to the second induction rotor segment parts 40b that induction plates 36 of the induction rotor segment parts 40a, 40b are positioned to face each other. Additionally, the second induction rotor segment parts 40b may be attached to each other by a connecting ring 53. The optional connecting ring 53 may be attached near inner edge 46 of each of the induction rotor segment parts 40b, for instance using bolts 48 or similar fastening means. Furthermore, the first induction rotor segment parts 40a are attached to main rotor 26 by respective segment couplings 59.

Spacers 42 are provided with slits 44. Slits 44 are configured to increase the air flow in between induction rotor segments 40. Further details about the spacers including a description of a specific embodiment thereof will be presented in connection with figure 16.

Figure 5 shows an exploded view of magnetic coupling assembly 2. Shown from left to right are the connecting ring 53, magnet rotor 8, pairs 40 of induction segment parts 40a, 40b, and the main rotor 26. The connecting ring 53 has a generally annular shape (defining an open space in its center allowing passage of the first rotary hub 4 and/or the first shaft 5 connected to the first rotary hub 4). As mentioned above, connecting ring 53 is provided with bolts 48. The bolts are inserted into induction segment parts 40b so as to bolt each of the induction rotor segment parts 40b onto the connecting ring 53. The bolts 48 may be distributed at an equal distance around connecting ring 53.

Referring to figure 5, magnet rotor 8 is provided with a plurality of through holes 14 configured for accommodating a plurality of permanent magnets. In other embodiments, not shown in the figures, the holes are blind holes (forming a pocket as it were wherein a magnet may be accommodated). Holes 14 extend from first side 16 to second side 18 of magnet rotor 8. In each through hole 14 an associated permanent magnet 20 is arranged. Through holes 14 and permanent magnet 20 are in the illustrated embodiment trapezium shaped, other shapes are possible as well.

Preferably, the adjacent permanent magnets 20 are arranged so that their respective magnetic poles are provided in an alternating manner. As an example, seen on first side 16, permanent magnet 20a has at first side 16 its north pole, adjacent permanent magnet 20b has at first side 16 its south pole, and permanent magnet 20c, which is positioned adjacent to permanent magnet 20b, has at first side 16 its north pole.

Each pair 40 of induction rotor segment part 40a, 40b comprises at least one (preferably two) spacers 42. Each induction rotor segment part 40a, 40b comprises a back plate 38 and at least one induction plate 36. Front plates 36 of induction rotor segment parts 40a, 40b are facing each other. In between induction plates 36 an inner space 50 is provided. The mutual distance between the induction plates 36 of facing induction rotor segments parts 40a, 40b is slightly larger than the local thickness of the magnet rotor 8 so that at both sides of the magnet rotor 8 a small air gap 27 (cf. figure 2) remains and the magnet rotor 8 may freely rotate between the induction segment parts 40a, 40b.

Referring to figures 5-11, the induction rotor 32 is coupled to the main rotor 26 by removably coupling the first induction rotor segment parts 40a to main rotor 26 by respective segment couplings 59. More specifically, each of the segment couplings 59 comprises an elongated connecting element 56 extending in a generally radial direction and mounted to back plate 38 of induction rotor segment 40a using a number of fasteners 66, for instance bolts, wherein the connecting element 56 is configured to be slidingly received in an associated recess 54, herein also referred to as a slit, provided in a connection surface 52 provided on one side of the main rotor 26.

Slits 54 generally extend in a radial direction, i.e. a radial direction corresponding to the radial direction of the connecting element 56. Induction rotor segment parts 40a can be removably coupled to the main rotor 26 by sliding the connecting element 56 in a radially directing inward (arrows in figure 9} into and along the radial slits 54. In the shown embodiment the radial slits 54 are substantially T-shaped in cross-section. Other shapes are possible as well. Connecting element 56 is substantially T-shaped in cross-section as well, with a projection 58 extending from back plate 38 and head 60 positioned at the end of projection 58. Head 60 extends in a direction perpendicular to the radial direction and axial direction, and parallel to the surface of back plate 38.

Since connecting element 56 is capable of being moved into and out of slit 54 {even if one or more neighboring induction rotor segments 34 have already been put into place) and since connecting element 56 and slit 54 are complementary shaped, the pair 40 of induction rotor segment parts 40a, 40b can be easily and firmly coupled to the main rotor 26 by an inward sliding action or can be easily removed from the main rotor 26 (for instance for maintenance or repair purposes) by an outward sliding action.

The number of radial slits 54 may correspond to the number of induction rotor segments 34 (in the shown embodiments the number is six) if each induction rotor segment 34 is coupled to the main rotor by using one single segment coupling. However, in other embodiments the number of segment couplings 59 for each induction rotor segment 34 may be larger (or smaller if the induction rotor segments 34 are mutually coupled as well).

More specifically, figures 7-10 show a preferred method of assembling the magnetic coupling assembly 2. In the illustrated embodiment first rotary hub 4 and second rotary hub 22 are already attached to first shaft 5 and second shaft 9 respectively (both first shaft 5 and second shaft 9 are not shown). Main rotor 26 is already attached to second rotary hub 22 and thus faces magnet rotor 8. Pair of induction rotor segments 40 can now be positioned over magnet rotor 8. Pair 40 of induction rotor segment parts 40a, 40b is positioned radially outwards of main rotor 26.

Connecting element 56 that is provided on induction rotor segment 40a is aligned with slit 54 of main rotor 26. Connecting element 56 is attached to induction rotor segment 40a with bolts 66 that extend into back plate 38. The pair of induction rotor segments 40a, 40b is moved in a radial direction towards the center of the assembly (i.e. towards the imaginary rotation axis R), such that connecting element 56 slides into slit 54. Head 60 of connecting element 56 is locked in the corresponding head shape of slit 54. In this way pair of induction rotor segments 40 are firmly attached to main rotor 26 and at the same time effectively aligned. Inner edge 62 of connecting element 56 abuts inner end 64 of slit 56. Permanent magnets 20 are then positioned in inner space 50 between induction plates 36. Inductor plates 36 are also positioned equidistant from permanent magnets 20 of magnet rotor 8.

Figures 19-22 show further embodiments of the present invention. While the magnetic coupling assembly may comprise at least one combination of a (first) main rotor 26 and a connecting ring 53 (as is shown, for instance, in figure 4), in these further embodiments the magnetic coupling assembly comprises one (in fact, at least one) combination of a first main rotor 26 and a second main rotor 126. As is shown in figure 19 and 20, both the first main rotor 26 and the second main rotor 126 may have been provided by radial slits 54. The slits 54 in the first main rotor 26 are located at similar positions in the second main rotor 126 so that each pair 40 of induction rotor segment parts 40a, 40b can be moved in a radial direction towards the center of the assembly, such that connecting elements 56 provided at both sides of each pair 40 of induction rotor segments 40a, 40b may slide into the respective slits 54 so as to tirmly attach them to the first and second main rotors 26, 126. An advantage of the present embodiments is that one can assemble some kind of protective cage (formed by the two main rotors arranged at both sides of the potentially dangerous magnet rotor) using essentially non-magnetic material (without a risk of body parts (fingers) of an individual to get stuck between magnetic parts and the magnets of the magnet rotor). Only once the protective cage has been arranged around the magnet rotor, the inductor segments parts are moved into place. Since the inductor segments parts are moved in place one-by-one the magnetic forces pulling on the inductor segments parts can be kept relatively small thereby further reducing the risk of injuries. While in the embodiment of figures 19 and 20 the spacers 141 have been attached to the first main rotor 26 and the second main rotor 126 so as to keep both rotors at a suitable mutual axial distance, in the embodiment of figures 21 and 22 the spacers 142 have been attached to the main rotors (i.e. the first and second main rotors) (while the induction segment parts 40a, 40b may move freely in axial direction over the spacers, as will be explained later) so as to keep both rotors at a suitable mutual axial distance (similar to the spacers 42 in the embodiments of figure 2-13). In the embodiment of figures 19 and 20 the induction segment parts 40a, 40b have cut-away corners 127 to allow the induction segments part 40a, 40b to be attached to the main rotor(s) while still providing space for the spacers 141 to be attached to the main rotors 26, 126.

The assembly order in the embodiments of figures 2-13 may be: placing the (potentially dangerous) magnet rotor on the first hub (often at the load side, sometimes at the drive side), placing the (essentially non-magnetic) main rotor 26 at a first side of the magnet rotor, attaching the pairs 40 of induction rotor segments (interconnected by spacers 42) one-by-one to the main rotor (keeping the magnet rotor in between the two induction rotor segment parts 40a, 40b, preferably right in the middle between the induction rotor segment parts) (wherein the attachment comprises sliding/pivoting/hinging or swiveling action for arranging the segments parts in a suitable end position and then fastening the segment parts to the main rotor in the end position by using fasteners 55, figure 13), and then (optionally) connecting the connection ring 53.

The assembly order in the embodiments of figures 21, 22 may become: placing the magnet rotor 8, placing the first main rotor 26 at a first side of the magnet rotor, placing the second main rotor 126 at a second, opposite side relative to the magnet rotor 8, and placing the pairs 40 of induction rotor segments (interconnected by spacers 142) one-by-one between the first and second main rotors (keeping the magnet rotor in between the two induction rotor segment parts 40a, 40b, preferably right in the middle between the induction rotor segment parts). In the embodiment of figures 19 and 20 wherein the spacers 141 are to be attached directly to the first and second main rotors 26, 126 (and not to the induction rotor segments) the assembly order may become: placing the magnet rotor, placing the first main rotor at a first side of the magnet rotor, placing the second main rotor at a second, opposite side relative to the magnet rotor, attaching the spacers 141 one-by- one between the first and second main plates 26, 126, and then consecutively attaching the induction rotor segment 40a or 40 one-by-one to respectively the first and second main rotor 26, 126.

While in the above-described embodiments the induction rotor segments are attached by a sliding action in an inward radial direction, in other embodiments an induction rotor segment is attached to a main rotor by a pivoting (swiveling or hinging) action. For instance, an inductor rotor segment 40a, 40b may be attached to a main rotor 26, 126 by a hinge, whereas the inductor rotor segment can be tilted from the outer position towards the final position of the segment onto the main rotor.

Referring to figures 11-14, a temperature indication unit 68 (in specific embodiments an overheating detection unit or a fail-safe unit) is shown. The temperature indication unit 68 is a unit configured to provide a warning signal (i.e. a visual signal, an acoustic signal or, preferably, an electronic signal if use is made of a contactless sensor, as will be explained later) in case of imminent overheating of the induction rotor 32 of the magnetic coupling assembly. Overheating is a general issue with magnetic couplings and may lead to malfunctioning of the coupling or even to dangerous situations for the immediate environment of the coupling: due to the large rotation speeds of the rotors of the coupling and/or the relatively large mass of the rotating components thereof, break-down of the coupling is to be avoided at all times. In case the temperature detection unit 68 generates an electronic warning signal, the drive unit 7 may be controlled to reduce its rotational speed or may even be controlled to stop rotating allowing the coupling to cool down.

Figures 11 and 12 show a particular embodiment of a temperature detection unit 68 in its normal (operational) state, while figures 13 and 14 show the same embodiment wherein the temperature detection unit is in its warning (operational) state.

The temperature indication unit 68 comprises a housing 73 mounted to at least one of the main rotor 26 and inductor rotor 32. Housing 73 has a first end 70 and a second end 72 (cf. figure 12, 14). Housing 73 is made of thermally conductive material to allow heat generated in the induction rotor 32 (more specifically in the induction and back plates thereof) and/or in the main rotor 26 to be transferred to the interior of the housing. In figure 12 it is shown that the end of the housing not only contacts the main rotor 26 but also extends through the main rotor 26 and the back plate 38 to contact the induction plate 36. In other embodiments the housing 73 only contacts the main rotor 26, only extends through the main rotor 26 to contact the back plate, or extends through the main rotor 26, the back plate 38 and at least partially through the induction plate 36.

The interior of the housing defines a cylindrical (or differently shaped) interior into which a sensing element 78, for instance a pin or similar elongated element may be arranged. In general, the sensing element may be configured to be axially movable in the housing (outwardly or inwardly), but in other embodiments the sensing element is configured to be radially movable or movable in an oblique direction (with both an axial and a radial component). In still further embodiments the sensing element is rotatably attached to at least one of the main rotor(s) and induction rotor(s) so that an end of the sensing element is movable in a circumferential direction (herein also referred to as the rotational direction) to generate the warning signal.

In the shown embodiment, the sensing element 78 is arranged in the interior of the housing via opening 75 and is configured to be movable in axial direction (i.e. in a direction parallel to the direction of the imaginary rotation axis R) inwardly or outwardly (towards or away from the main rotor 26, respectively).

Near first end 70 the interior of the housing defines a chamber 74 is arranged. The part of the housing 73 at the end first end 70 of the chamber 74 (or, in other embodiments wherein the housing is open at its first end 7. the retainer material 76 inside the chamber 74) is partly in contact with induction plate 36 of induction rotor segment 40a (or 40b). Due to being in contact with induction plate 36 (or, in other embodiments, to the back plate 38 and/or the main rotor 26), a rise in temperature in the induction rotor (especially in the induction plate 36 thereof) will cause a rise in temperature inside chamber 74. In chamber 74 thermally conductive and meltable material 76 is provided. Material 76 is selected to have a melting point that substantially coincides with or has a fixed relation to a preselected temperature, for instance a critical temperature like a maximum desired temperature of induction rotor 32.

Figures 11 and 12 show the earlier-mentioned sensing element 78 of the temperature detection unit 68 in its normal (operational) state. In the normal state securing end 82 of sensing element 78 (i.e. the end closest to the source of heat, that is closest to the induction plate 36) is firmly secured inside the housing 73 due to the fact that it is surrounded by the material 76 that is in a solid (not yet melted) state. To increase the grip of the material 76 onto (securing end 82 of) the sensing element 78 one or more circumferential flanges or ridges 84 are provided. Due to the one or more ridges 84 sensing element 78 has a higher resistance to material 76 and therefore material 76 grips sensing element 78 more tightly. In normal state sensing element 78 is positioned substantially completely inside housing 73. Further provided in the interior of housing 73 is resilient element 88, in this embodiment shown as a spring, for instance a coil spring. Resilient element 88 is configured to bias sensing element 78 towards opening 75 of housing 73 at outer end 72. The biasing is achieved by resilient element 88 resting on top wall 90 of chamber 74 and abutting and pressing against an abutment part 92 of sensing element 78. For instance, the abutment part may be formed by a circumferential protrusion or, in the shown embodiment, a circumferential thickening of the sensing element 78.

Temperature detection unit 68 is in figures 13 and 14 shown in warning state 86. Due to a temperature increase in the induction rotor 32 the temperature of the retainer material 76 inside the chamber 74 is raised. Eventually the temperature in chamber 74 reaches a level wherein the material 76 starts to melt. Once the material 76 has been sufficiently melted (or at least caused to become softer), the grip of the material 76 on the sensing element 78 is reduced so that the biasing force of the resilient element 88 finally becomes larger than the gripping force of the material 76 so that the sensing element 78 is forced to move outwardly so that the outer end of the sensor element 38 is moved out of the housing. Figures 13 and 14 show the state wherein the sensing element 78 has been moved outwardly over distance sufficient to generate a warning signal. This warning signal could be a visual warning signal since the sensing element 78 in the warning state 86 is projecting out of the housing which will be visible by the operator of the magnetic coupling assembly. The operator may take appropriate action, for instance reducing the speed of the drive unit shaft or even completely bringing the coupling assembly to a standstill. In other embodiments the movement of the sensing element from the normal state to the warning state will trigger an external sensor (i.e. a stationary sensor positioned remotely from the rotating parts of the magnetic coupling assembly), which external sensor then generates an electronic warning signal, as will be explained hereafter.

The retainer material 76 could be any material that is capable of retaining the sensing element 78 in place against the biasing force (i.e. a pulling force or a pushing force) of the resilient member 88 when the temperature in the chamber 74 is below a critical (melting temperature), while becoming soft enough to allow the sensing element 78 to be moved outwardly (ejected) once the temperature exceeds the critical temperature. The critical temperature may be defined as the maximum temperature at which the coupling assembly may function safely. Examples of this material are tin, zinc, or similar materials like fusible alloys which have a specific composition of to achieve an exact melting point with a high liquid fluidity. These fusible alloys often have a low melting temperature.

As mentioned above, in the embodiment shown in the figures, in warning state 86 sensing element 78 has been moved outwardly so as to partially extend outside the second end 72 of housing 73. In other embodiments, the sensing element 78 is caused to move in the opposite direction, i.e. inwardly when going from the normal state to the warning state. In the latter embodiments the fact that a sensing element has been moved to the warning state can be detected visually (for instance by an operator) to generate a visual warning only or can be sensed by an external sensor to generate an electronic signal. The following description of the operation of the external sensor in case of a sensing element moving outwardly can be similarly applied to a sensor element moving inwardly, radially, obliquely or in a rotational direction.

In some embodiments of the present disclosure the movement of the sensing element 78 from the normal state to the warning state is accomplished by the centrifugal forces (g-forces) exerted onto the sensing element when the rotors of the coupling assembly are rotating. This may for instance be the case in embodiments wherein the sensor element is arranged to be movable in the radial direction or at least in a direction that has a radial component. Once retainer material 76 is melted to the extent that the sensing element 78 can no longer be retained in the housing, the centrifugal forces urge the sensing element to move to the warning state.

In other embodiments the movement of the sensor element 78 needs to be generated by a biasing element. An example of a biasing element may be a resilient member 88. The biasing element (resilient member) may be configured to bias the sensing element in an outward direction or in an inward direction. In the following an embodiment is described wherein the biasing element is configured to urge the sensing element in an outward direction once the sensing element can no longer be retained by the retainer material 76. However, it will be appreciated that the biasing element could similarly be arranged to urge the sensing element in an inward direction once the sensing element can no longer be retained by retainer material 76. It may even be possible to configure the biasing element (resilient member) to cause a rotatably mounted sensing element to move the sensing element to the warning state once the sensing element can no longer be retained.

In a further embodiment the magnet coupling assembly comprises a plurality of temperature detection units 68 wherein each of the temperature detection units is configured to have a different preselected temperature. For instance, in a first temperature detection unit 68 the preselected temperature is a relatively low first critical temperature while in a second first temperature detection unit 68 the preselected temperature is a relatively high second critical temperature while. When the induction rotor is heated the first, relatively low temperature is reached first causing the controller to take first measures like reducing the rotation speed of the drive shaft 9 of the drive unit 7 or only generating an audible and/or visible warning signal, while when the temperature still increases and reaches the second, higher temperature. the controller completely shuts down the drive unit 7.

As shown in figures 11-14, resilient element rests on ceiling 90 of chamber 74 and abuts abutment part 92 of sensing element 78. Resilient element 88 is able to move sensing element 78 due to the melting of material 76. Due to sensing element 78 extending out of second and 72 of housing 73, proximity sensor 94 measures that 78 extends out of housing 73. Based on the detection of proximity sensor 94 an electronic warning signal is generated. This signal may be received via a wireless or wired connected by an electronic controller configured to control at least the drive unit 7. Based on the received warning signal the controller may control the drive unit 7 to lower the rotation speed of the second shaft (driving shaft) 9. Alternatively or additionally, the controller may control a warning signal generator like a loudspeaker or a lamp to generate an audible and/or visible warning signal.

Each of induction rotor segment parts 40a, 40b (figures 15 and 16) comprises in this embodiment a back plate 38, while each back plate 38 is provided with a plurality of associated induction plates 36a, 36b rather than only one single back plate 38 as in earlier described embodiments. Backplate 38 and first induction plate 36a are separated by axial distance Dj. First induction plate 36a and second induction plate 36b are separated by axial distance Ds. The axial distances between plate 38 and induction plates 36a and 36b are achieved by rings 96 that are provided in between the plates 36a, 36b, 28. The interspace provided between plates 38, 36a, 36b increases the airflow when the plates are rotating, thereby reducing the temperature of the plates 38, 36a 36b, in particular of induction plates 36a, 36b.

The spacers 42 may have a constant length in order to ensure a constant distance between the segments 40a, 40b. However, according to other embodiments, the length of the spacers 42 (defining the axial distance between opposing second induction plates 36b or between opposing induction plates 36 in embodiments wherein the length-adjustable spacer is applied to the earlier- described embodiments of figures 1-14) may be adjustable. For instance, in the embodiment shown in figures 15 and 16, the spacer comprises a female spacer part 42a and a male spacer part 42b.

Male spacer part 42b comprises an outer thread and female spacer part 42a comprises an inner thread. Distance D3 between induction plates 36b can be adjusted by relative rotation of male spacer part 42b and female spacer part 42a.

While in the exemplifying embodiments described thus far the inductor plate 36 of an induction rotor segment part 40a, 40b is an essentially solid plate, figure 17 shows another embodiment wherein the inductor plate 36° of the inductor rotor 32 has one or more slots 43 (the number of slots shown is seven, but this number could be larger or smaller). Such slotted inductor plate 36° has the advantage that the pate may be additionally cooled by the relatively cool ambient air that is caused to flow along the exposed parts (i.e. the regions where the slots 43 are located) when the magnetic coupling assembly is rotating. Alternatively or additionally, the one or more slots 43 in one or more of the inductor plates makes it possible to vary the torque curve (transmission characteristic) of the coupling assembly. Referring to the embodiment shown in figures 20-23, 24A, 24B, the spacers 142 are attached with their opposing ends to a first backplate 38 at one side and a second backplate 38 at a second, opposite side. The induction plates 36a, 36b can move freely over the outer surface of the spacers 142 (by forming openings in the induction plates 36a, 36b with a diameter slightly larger dan the diameter of the spacers 142) so that their mutual axial distance (d) can be varied by sliding the induction plates back and forth. For instance, figures 24A and 24B show the result of this operation. In figure 24A the mutual distance d; between a back plate 38 and the first induction plate 36a is relatively large, while figure 24B shows a situation wherein the mutual distance d» between a back plate 38 and the first induction plate 36a is relatively small. The mutual distance is set by means of a set of secondary spacers 152. The secondary spacers 152 may be comprise of an elongated element 154 provided with external screw thread and a head 153. The secondary spacer 152 that may be screwed into the openings 150 in the induction plates 36a, 36b and back plate 38 thereby adjusting the gap between them (so as to fix the plates at a suitable mutual distance). The axial position of the magnet rotor can remain unchanged during this operation.

In many of the embodiments described herein there is induction material arranged at both sides of the magnet rotor 8 (see, for instance, the embodiments of figures 1-13, 18-24B. See also figures 27 and 28 showing a first main rotor 26, a second main rotor 126, and first induction rotor 32 next to the first main rotor 26 and a second induction rotor 32 next to the second main rotor 126), i.e. induction material (rotor segment parts) at one side and induction material (rotor segment parts) at the other side (seen in axial direction) of the magnet rotor 8. However, in further embodiments, induction material may be arranged at one side only of the magnet rotor 8 (for instance in light-weight application wherein the torque exerted on the load/driving shafts are restricted). Such embodiment is shown in figures 25 and 26. The figures show an embodiment wherein the magnetic coupling assembly comprises a first main rotor 26, a second main rotor 126, and a single induction rotor 32. More specifically, the magnetic coupling assembly has the following arrangement (from right to left): main rotor provided with spacers - inductor set/rotor - magnet rotor (not shown) - inductor set/rotor. The induction rotor may be formed by one single induction plate or by various induction plate segments, as described herein.

In several embodiments described herein the spacers 42, 142 have a fixed length. However, in other embodiments the spacers may have an adjustable length. For instance, the spacers 143 may be of a telescopic type wherein their length can be manually made larger or smaller by having an operator rotate the spacers in a suitable direction (when the rotors of the magnetic coupling assembly are stationary). In still other embodiments the spacers have a fixed length but still enable adjustment of the axial distance between rotors of the magnetic coupling assembly. This is for instance the case in the embodiment shown in figures 25 and 26 and in the embodiment of figures 27 and 28. A spacer 43 may be configured to adjust the axial distance between two elements that are spaced apart by the spacer (for instance a first and second inductor rotor or induction rotor segment) by arranging the threaded parts (for instance threaded end parts comprised of external threading, one part being provided with left-hand thread and the other, opposite part being provided with right-hand thread) ) in threaded openings (i.e. the openings being provided with internal threading) into which the external threading provided on the spacer engages so that (manually) turning the spacer causes the two elements to be moved in axially direction towards or away from each other to reduce resp. increase their mutual distance. In still other embodiments the gap between the rotors can be adjusted using the above-mentioned secondary spacers 152.

The present invention is by no means limited to the above-described exemplifying embodiments thereof. The rights sought are defined by the following clauses within the scope of which many modifications can be envisaged.

Claims (20)

CONCLUSIONS 1. A magnetic coupling assembly for coupling a first rotating shaft and a second rotating shaft, the magnetic coupling assembly comprising: - a first rotating disk connectable to the first shaft; - a second rotating disk connectable to the second shaft; - a magnetic rotor comprising a set of permanent magnets, the central magnetic rotor being coupled to the first rotating disk and being adapted to co-rotate with the first rotating disk; - an induction rotor being directly or indirectly coupled to the second rotating disk and being adapted to co-rotate with the second rotating disk; and - a temperature detection unit being adapted to detect a predetermined temperature of at least a portion of the induction rotor, the temperature detection unit comprising: - a housing comprising a chamber at a first end of the housing, the chamber being at least partially in direct or indirect thermal contact with the induction rotor; - a detection element disposed within the housing and having a retaining end extending into the chamber, the detection element being movable within the housing between a first position representing a normal condition and a second position representing a warning condition; and - mounting material positioned within the chamber of the housing, the mounting material being solid below a predetermined temperature under atmospheric conditions and melting above the predetermined temperature, wherein at temperatures in the chamber below the predetermined temperature the mounting material secures the retaining end of the detection element such that the detection element remains in the first position and at temperatures at or above the predetermined temperature the mounting material permits the detection element to move from the first position to the second position. 2. The magnetic coupling assembly of claim 1, wherein the housing and the sensing element are positioned relative to the induction rotor such that rotation of the induction rotor causes the sensing element to move from the first to the second position. 3. The magnetic coupling assembly of claim 2, wherein the sensing element in the housing extends in a radial direction. 4. A magnetic coupling assembly according to any preceding claim, further comprising a bias element, the bias element being configured to bias the detection element to move from the first to the second position. 5. Magnetic coupling assembly according to claim 4, wherein the inclination element is an elastic element arranged in the housing, for example a spring, specifically a coil spring arranged around the detection element. 6. A magnetic coupling assembly according to any preceding claim, wherein in the first position the detection element is positioned substantially within the housing while in the second position an emd of the detection element extends outside the housing. 7. A magnetic coupling assembly as claimed in any one of claims 1 to 5, wherein in the first position an end of the detection element is positioned to extend outside the housing while in the first position the detection element is positioned substantially within the housing. 8. A magnetic coupling assembly according to any preceding claim, wherein the sensing element is a pin mounted in the housing so as to be movable in at least one of an axial direction, a radial direction, and a circumferential direction. 9. A magnetic coupling assembly according to any preceding claim, comprising a first temperature sensing unit having mounting material having a first value of the predetermined temperature and a second temperature sensing unit having mounting material having a second value of the predetermined temperature, the second value being greater than the first value. 10. A magnetic coupling assembly as claimed in any preceding claim, wherein the sensing element is a pin extending from its retaining end into the chamber. 11. A magnetic coupling assembly according to claim 10, wherein the pin comprises a support member, for example a protrusion, wherein a biasing element is provided to extend between an upper wall of the chamber and the support member. 12. A magnetic coupling assembly according to any preceding claim, wherein the locking end of the detection clement is provided with edges. 13. A magnetic coupling assembly according to any preceding claim, wherein the detection element is a ball provided in the housing. 14. A magnetic coupling assembly according to any preceding claim, wherein the detection element is a pin pivotally connected to the housing or the induction element, for example a cam. 15. A magnetic coupling assembly according to any preceding claim, wherein the interior of the housing has a substantially cylindrical shape. 16. A magnetic coupling assembly according to any preceding claim, further comprising a second mechanism, preferably mounted in a stationary manner relative to the rotatable portions of the magnetic coupling assembly, positioned at a distance from the induction rotor such that the sensing element contacts the second mechanism during rotation of the induction rotor only when the sensing element is in the second position. 17. A magnetic coupling assembly according to any preceding claim, further comprising a sensor, preferably a proximity sensor, arranged to be disposed at a distance from the induction rotor and arranged to detect whether the detection element has moved from the first to the second position. 18. A magnetic coupling assembly according to any preceding claim, further comprising: - a main rotor connected to the second rotating disk and adapted to co-rotate with the second rotating disk; and - an induction rotor coupled to the main rotor, the induction rotor being indirectly connected to the second rotating disk via the main rotor and optionally the induction rotor comprising a plurality of induction rotor segments, each of the induction rotor segments being coupled to the main rotor with a segment coupling. 19. A magnetic coupling assembly according to any preceding claim, wherein the main rotor and the induction rotor are joined together to form an integrated rotor and/or wherein the main rotor and the second rotating disk are joined together to form an integrated rotor disk element. 20. Use of the magnetic coupling assembly according to any of the preceding claims.