FIELD OF THE INVENTION

The invention relates to a portable foodstuff mixer, and in particular an electric, e.g. mains-powered or battery- powered vortex mixer suitable for mixing or blending

ingredients, such as drinks, protein shakes, or other viscous foodstuffs .

BACKGROUND TO THE INVENTION

Many types of health supplements require mixing of two or more ingredients. For example, protein shakes or meal replacement supplements are often provided as a powder or paste to be mixed with a base liquid (e.g. water or milk) to form a viscous foodstuff for consumption.

Conventionally, mixing is performed by manually shaking the ingredients in a suitable container, such as a bottle. But it is difficult to obtain a uniformly smooth mix from this technique .

Conventional food blenders can also be used for mixing this type of drink, but they are not easily portable, and the mechanical stress caused by blending in these devices can have an adverse effect on the health supplements.

More recently, portable electric mixers have been developed specially to address the above problems. One example of such a mixer is the PROMiXX vortex mixer, in which a rotatable blade is mounted in the base of a vessel. The vessel can be mounted on a base that contains a motor. The rotatable blade is drivably coupled to the motor through a mechanical coupling, whereby liquid in the vessel is mixed through a vortex action and associated fluid shear forces, created by a combination of the shape of the rotating blade and the internal form of the vessel.

The vessel can be in the form of a bottle from which the mixed liquid can be consumed or dispensed.

SUMMARY OF THE INVENTION At its most general, the invention provides a portable foodstuff mixer in which a magnetic coupling is used to operably connect components. In particular, the invention may relate to a portable foodstuff mixer in which a magnetic attraction force acts as the primary link between a rotatable mixing element and a motor. In some examples, the magnetic coupling may also provide or assist in connecting other components, e.g. a mixing vessel and base in a portable electric foodstuff mixer. In such an example, the portable foodstuff mixer can comprise: a base housing a motor, and a mixing vessel comprising a mixing element, wherein the mixing vessel is retained on the base by a magnetic coupling, and wherein the mixing element is drivable by the motor through the magnetic coupling. Providing a magnetic coupling can enable a structurally simpler interface between the mixing vessel and base to be achieved. This may be of benefit in terms of manufacturing costs and the ease with which a user can operate the mixer.

According to one aspect of the invention, there is provided a portable foodstuff mixer, comprising: a base housing a motor, and a mixing vessel comprising a mixing element, wherein the mixing vessel is retained on the base, wherein the mixing element is rotatably mounted in the mixing vessel, and wherein the mixing element is drivable by the motor though a magnetic coupling to rotate relative to the mixing vessel about a rotation axis, wherein the magnetic coupling comprises: a vessel portion having a first magnetic element connected to rotate with the mixing element relative to the vessel by a shaft that passes through an aperture in the bottom surface of the mixing vessel associated with the vessel, and a base portion having a second magnetic element that is rotatably mounted on the base and drivable by the motor to rotate relative to the base, wherein the first magnetic element and the second magnetic element are arranged to couple to each other at an engagement interface, and wherein the vessel portion and base portion include contact portions that abut one another when the first magnetic element and the second magnetic element are coupled at the engagement interface. The magnetic coupling may facilitate efficient transfer of the motor drive, whilst the physical contact can be used to ensure proper alignment. By using the magnetic coupling as the main route for transferring drive, the physical contact can be minimised to avoid unwanted frictional forces. The contact portions may move with the shaft, i.e. be drivable relative to the vessel by the motor, but this is not essential. In some examples, the magnetic coupling occurs at a non-contact interface, and the contact between the vessel portion and base portion is provided by separate engagement features, such as a twist-lock mechanism or the like.

The mixing vessel may be detachably mountable on the base. A detachment interface, i.e. a point or plane or separation between the mixing vessel and base, may be at the magnetic coupling. In other words, the magnetic coupling may detachably retain the mixing vessel on the base. The magnetic coupling may retain the mixing vessel on the base using an attractive magnetic retention force. The magnetic retention force may selected to be strong enough to secure the mixing vessel to the base during operation of the motor, but weak enough to permit manual separation of the mixing vessel from the base. The magnetic retention force may be greater than 15 N; it may be less than 20 N. In other examples, a physical engagement mechanism, such as a twist-lock mechanism or bayonet connection, can be used to retain the vessel on the base, and the magnetic coupling may be to transfer drive from the motor to the mixing element. The physical engagement mechanism may be provided by the contact portions on the vessel portion and base portion.

The portable foodstuff mixer may be an electric vortex mixer, e.g. for mixing a food supplement (e.g. in powder or paste form) into a base liquid. The mixer may also be suitable for blending solid foodstuffs, depending on the configuration of the mixing element. The mixing element may be rotatably mounted in the mixing vessel, and wherein the mixing element is drivable to rotate relative to the mixing vessel about a rotation axis. The rotation axis may be oriented to extend in an upright (e.g. vertical) manner from a bottom surface of the vessel. The mixing element may thus create a swirling motion in liquid present in the mixing vessel. The mixing element may be configured, i.e. may have a size and geometry selected, to induce vortex action in liquid carried by the mixing vessel. The vessel portion may be associated with the vessel and the base portion may be associated with the base. Herein, "associated with" may mean "mounted on", "connected to", "connected in", or "retained by". The magnetic coupling may thus comprise a pair of components, which may be separable to provide the detachment function discussed above.

The engagement interface may be defined as a joint or region of close proximity (but not necessarily contact) between the first magnetic element and the second magnetic. The first magnetic element and the second magnetic element may be shaped in a manner whereby they cooperate at the engagement interface. This may ensure that the magnetic retention force has a smooth or uniform profile across the engagement

interface. In one example, the first and second magnetic elements have respective exposed surface at the engagement interface. The exposed surfaces may be flat, and may protrude slightly from their immediate surroundings.

Either or both of the first magnetic element and the second magnetic element may be a permanent magnet, e.g. made from a suitable neodymium alloy or the like. The first magnetic element and the second magnetic element are

preferably arranged (i.e. are mounted in their respective coupling portions) to present opposite magnetic polarities at the engagement interface. The first magnetic element and the second magnetic element may be arranged to abut each other at the engagement interface. For example, the exposed surfaces may be in contact with one another when the mixing vessel is mounted on the base.

The shaft may pass through the aperture in the bottom surface of the mixing vessel into an internal volume of the mixing vessel for receiving ingredients to be mixed.

The shaft may extend through the first magnet to form the or part of the contact portion. In this arrangement, the contact portions may provide engagement between a lower end of the shaft and a shaft mounting region on the base portion. The shaft mounting region may extend through the second magnetic element. For example, the first and second magnetic elements may each comprise a ring-shaped magnet having a central through hole through which the shaft or the shaft mounting region extend. The shaft mounting region may comprise a recess configured to retain the shaft in an upright orientation. For example, the recess may have a spherically convex shape that acts to self-align the shaft (i.e. resist angular displacement of the shaft) .

The vessel portion may comprise an upper housing (e.g. an inverted cup) for receiving the first magnetic element. The base portion may comprise a lower housing (e.g. a plate) for receiving the second magnetic element. The contact portions may be formed by the upper housing and lower housing. For example, the upper housing may comprise a skirt having a undulating lower edge arranged to cooperate with the lower housing. The undulating lower edge may resemble a series of teeth that interlock with corresponding teeth on the lower housing .

The shaft may pass through a vessel seal, which can be retained in the aperture. The vessel seal may be a moulded component that is resiliently deformable to sealingly engage around the shaft. The vessel seal may engage the shaft at an upper seal point and a lower seal point, between which is defined a internal cavity. In use, the shaft rotates relative to the vessel seal. The internal cavity may be filled with hydrophobic grease to prevent leakage from the internal volume. The vessel seal may in turn be retained by vessel base plug, which is secured on an underside of the vessel. The vessel seal may comprise a radial flange that is

sandwiched against the underside of the vessel by the base plug .

The mixing element may be mounted on the shaft via a shaft cap. The mixing element and shaft cap may be integrally formed, e.g. as a single moulded unit. The shaft cap may be secured to the shaft by any suitable means, e.g. friction fit, overmoulding, bonding, etc. For example, the shaft cap may be mounted over a first end portion of the shaft, where the first end portion is threaded to inhibit relative rotation between the shaft cap and shaft. Herein the term "threaded" is used to indicate the presence of helical ridges (similar to a screw) on a male component intended to be received in a female component. The first end portion may be threaded in a rotational sense that acts to drive the shaft cap further down on to the shaft if the mixing element is forced to rotate against the driven rotational direction, e.g. by resistance of a fluid being mixed. In one example, the driving rotation direction is clockwise, so the threaded direction is counter clockwise. The first end portion may be configured in other ways to achieve a similar effect. For example, it may have axially extending splines formed thereon.

As mentioned above, the shaft cap may be simply

overmoulded on to the first end portion of the shaft.

Alternatively, the shaft cap may have a mounting hole formed therein, which can be tapped to cooperate with the thread on the first end portion of the shaft. The connection between the shaft cap and the shaft may need to transmit a magnetic coupling separation force when the mixing vessel is detached from the base. The connection may therefore be arranged to such that the force required to separate the shaft cap from the shaft is greater than that required to separate the first and second magnetic elements.

The first magnetic element may be mounted on a second end portion of the shaft via a first retaining cup. The first retaining cup may be a moulded component arranged to secure the first magnetic element in a manner that inhibits relative movement between the retaining cup and first magnetic element in a rotational and axial sense. As explained below, the second magnetic element may be mounted in a similar way in a second retaining cup. The shape and configuration of the first and second magnetic elements may be substantially identical, in that they may resemble mirror images of each other across the engagement interface. The following

preferred or optional features of the first magnetic element may thus be equally applicable to the second magnetic element.

In order to retain the first magnetic element in an axial sense, it may comprise a body that tapers towards (e.g.

narrows in cross-section towards) the engagement interface. The first retaining cup may include a rim that extends around the periphery of the body to secure it axially.

In order to retain the first magnetic element in a rotational sense, one or more recesses or keyways may be formed around the periphery of the body in a direction normal to the rotation axis. The first retaining cup may include fingers or other projections that are received in the recesses or keyways to inhibit relative rotational movement between the first magnetic element and the first retaining cup. The body of the first and/or second magnetic element may have a disc shape. The exposed surface may be a flat round surface of the disc. The tapering of the body may correspond to a reduction in disc diameter.

The body of each magnetic element can be secured in its respective retaining cup in any suitable manner. For example, it may be by a press fit, or the retaining cup may be

overmoulded on to the magnetic element. In other examples, bonding may be used. However, it may be important for the connection to be arranged to be such that the force required to separate each retaining cup from its respective magnetic element is greater than that required to separate the first and second magnetic elements.

The motor may comprise a spindle that passes through an aperture in a top surface of the base, and wherein the second magnetic element is drivably connected to the motor via the spindle. As mentioned above, the second magnetic element may be mounted in a second retaining cup, which itself may be mounted on a tip portion of the spindle. The second retaining cup may include a radially extending rim (e.g. in the form of an annular skirt) which covers the junction between the spindle and the top surface of the base in order to prevent unwanted ingress of liquid towards the motor. The second retaining cup may be spaced slightly away from the top surface so as not to restrict rotation of the spindle.

The tip portion may be threaded to inhibit relative rotation between the spindle and the second retaining cup. As discussed above, the threading may be in a sense that opposes rotation opposite to the driven rotation direction. The second retaining cup may be a moulded component arranged to secure the second magnetic element to inhibit relative movement between the retaining cup and second magnetic element in a rotational and axial sense. The features disclosed above with reference to the first magnetic elements may be applied here .

The mixing vessel may have a circumferential skirt that extends around a bottom edge therefore to define a recess for receiving the base. The first magnetic element may thus be set back from a bottom-most edge of the vessel. This may prevent damage to the magnetic element when the vessel is detached. The recess may be shaped to cooperate with a top surface of base. This may facilitate mounting the two components together.

The skirt may comprise one or more engagement features arranged to cooperate with corresponding engagement features on the base to inhibit relative rotation between the base and mixing vessel in a direction in which the mixing element is driven. The engagement features may resemble a simple twist- lock attachment, where a finger or projection on one of the components (e.g. the skirt) is received in a corresponding slot on the other component (e.g. the base) . In embodiments of the invention, these engagement features may be secondary to the magnetic coupling. For example, this engagement feature needs not provide any axial retention capability because that may be provided primarily by the magnetic coupling. In other examples, the primary purpose of the magnetic coupling may be to transfer a rotary drive to the mixing element. In such an example, these engagement features may provide the contact portions between the vessel portion and base portion, and may axially retain the vessel relative to the base. For example, the engagement features may comprise a twist-lock or bayonet connection.

The device may be powered by an external or internal power supply. For example, it may be main-powered or battery- powered. The base may comprise a power source for the motor. The power source may be a battery or the like. The power source may be rechargeable, and the base may comprise a suitable recharge port for connection to an external power supply. For example, the battery may be rechargeable via a USB port, e.g. a micro or macro USB port.

The base may comprises a status indicator, such as an LED or the like. This may be used to show battery charge status, operational status, fault condition, etc. An activation switch (e.g. push button) for operating the mixer may also be mounted on the base.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are discussed below with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a portable foodstuff mixer suitable for implementing the present invention; Fig. 2 is a cut-away perspective view of a magnetic coupling for a portable foodstuff mixer that is an embodiment of the invention;

Fig. 3A is a perspective view of a magnet used in the magnetic coupling of Fig. 2;

Fig. 3B shows the magnet of Fig. 3A in an overmoulded housing;

Fig. 3C shows the overmoulded housing of Fig. 3B mounted on a motor spindle;

Fig. 3D shows a base for a portable foodstuff mixer that incorporates a base portion of the magnetic coupling of Fig. 2;

Fig. 4 is a schematic cross-section of a bottle for a portable foodstuff mixer that incorporates a bottle portion of the magnetic coupling of Fig. 2

Figs. 5A and 5B are exploded and assembled views

respectively of a base coupling element of a magnetic coupling that is an embodiment of the invention;

Figs. 6A and 6B are exploded and assembled views

respectively of a vessel coupling element of a magnetic coupling that is an embodiment of the invention; and

Fig. 7 is a schematic cross-sectional view of a connected magnetic coupling comprising the base coupling element of Fig. 5B and the vessel coupling element of Fig. 6B.

DETAILED DESCRIPTION; FURTHER OPTIONS AND PREFERENCES

Fig. 1 shows a perspective view of a portable foodstuff mixer 100 in which a magnetic coupling according to the invention can be implemented. The mixer 100 is an electric vortex mixer. It comprises a base 102 on to which a mixing vessel (referred to below as a bottle) 104 can be detachably mounted. In this example, the bottle 104 is a cylindrical vessel, e.g. formed from moulded plastic or the like, that defines an internal volume in which liquid foodstuff can be mixed. In the example shown in Fig. 1, the bottle 104 gently tapers towards the base 102.

A cap 106 is mounted at the top of the bottle 104 to enclose the internal volume. The cap 106 has a closure feature 108 that is arranged to open and close an aperture through the cap 106 to enable access to the internal volume, e.g. to consume the mixed liquid or to introduce ingredients. The cap and closure may be conventional.

A mixing element 110 is rotatably mounted on the bottom surface of the bottle 104 such that its axis of rotation extends vertically through the internal volume when the bottle

104 is mounted on the base 102. The mixing element may have any construction suitable for creating a vortex action within liquid in the internal volume when the mixing element 110 is rotated about the rotation axis. The mixing element may be a blade or other substantially planar element having a geometry arranged to push liquid towards and around a peripheral surface of the bottle.

In use, the rotatable mixing element 110 is driven by a motor (not shown) that is mounted in the base 102. The motor may be any suitable rotatory drive mechanism. The motor may be a high torque brushed DC motor, e.g. capable of delivering about 4 of mechanical power. The speed of operation will depend on the nature of the contents but may spin at around 5000 rpm under load.

The motor may be powered by one or more batteries (not shown), which are also mounted in the base 102. The motor can be activated by pressing a push button 114 on the base.

Activation of the motor causes rotary motion of a vertically extending spindle which is coupled to the rotatable mixing element 110 via a coupling mechanism 112, which utilises a magnetic engagement.

In embodiments of the invention, the bottle 104 is retained on the base 102 in the axial sense, i.e. in a sense preventing movement along the rotation axis. This axial retention may be provided by the magnetic engagement, or by the magnetic engagement in combination with another physical coupling. To prevent relative rotation between the base 102 and the bottle 104 during operation of the motor, the bottle 104 and base 102 may be provided with cooperating mechanical engagement features 116 which operate to resist relative rotation between the bottle 104 and base 102. In one example, the cooperating features may be a circumferentially extending finger that is receivable in a corresponding slot. The extent to which the finger can move circumferentially within the slot may be constrained by the geometry of the engagement to prevent the relative rotation. The finger may be provided on the base, and the slot on the bottle or vice versa. The invention is not limited to the presence or nature of these engagement features. They may be implemented in a variety of ways, e.g. by threaded engagement between the bottle and base, etc .

Fig. 2 shows a perspective view of the coupling 112 between a motor spindle 132 and rotatable mixing element 110. The view in Fig. 2 is cut away down the rotation axis to enable the components to be shown more clearly.

The coupling 112 comprises a bottle portion which is mounted in the bottle 104 and includes the rotatable mixing element 110, and a base portion, which is mounted in the base 102 and includes the spindle 132 that is driven by the motor (not shown) . The bottle portion and base portion are

connected to each other via a magnetic engagement between a first magnet 124 and a second magnet 138.

The first magnet 124 is in the bottle portion. The first magnet is in the shape of a disc, and is retained in an overmoulded housing 126. The overmoulded housing is connected to one end of a shaft 120, which has the rotatable mixing element 110 mounted at its other end. The shaft 120 is rotatably mounted at the bottom of the bottle 104 (see Fig. 4) .

The overmoulded housing 126 forms a cup to retain the first magnet 124. The first magnet 124 has tapering side surfaces which assist in retaining the first magnet within the housing 126.

The shaft 120 is retained in the overmoulded housing 126 by a pair of inward protrusions 128. The shaft 120,

overmoulded housing 126, and first magnet 124 are therefore arranged to move as one piece.

The mixing element 110 is a moulded component, e.g.

formed from plastic or the like. The mixing element includes a overmoulded shaft cap 118 that is mounted on the top end of the shaft 120. To prevent relative rotation between the mixing element and the shaft, e.g. caused by resistance of the fluid during mixing, the top end of the shaft 120 is threaded, e.g. to size M2. This has the effect of increasing the separation force between the mixing element moulding and the spindle. Threading the end of the shaft in a sense that runs opposite to the sense in which the mixing element will be rotated by resistance of the fluid means that the engagement between the shaft 120 and overmoulded shaft cap 118 can be positively enhanced during use. In another embodiment, the top end of the shaft 120 may have radially protruding axial splines to achieve a similar function. Axial splines may be preferred to threading.

The base portion of the coupling 112 comprises the second magnet 138 mounted in a respective overmoulded housing 136 which in turn is connected to the spindle 132 that is driven by the motor (not shown) . The motor is typically encased in a housing 130. The spindle 132 protrudes from the housing, e.g. through a suitable bearing 134.

A top end of the spindle 132 may have a threaded portion 140 in a similar manner to the tap portion 122 of the shaft 120 in order to inhibit relative rotation between the

overmoulded housing 136 and spindle 132 in use.

Fig. 2 shows the coupling 112 in an engaged position, where the first magnet 124 and second magnetic 138 have exposed surfaces in abutment, whereby the bottle portion is secured to the base portion by magnetic attraction. The magnets may be selected to provide an attractive force of at least 17.5 N. In one example, the magnets are made from N42 grade Neodymium Iron Boron alloy. The attractive force (also referred to as the separation force) between the magnets is preferably chosen such that when the motor is turning and coupled via the magnetic force to the mixing element, any force applied to the mixing element that is sufficient to stop it turning will cause the motor to stall before the magnet coupling slips.

The magnetic engagement discussed above is advantageous in comparison with a conventional mechanical linkage both in terms of providing a simpler assembly procedure and in terms of increasing the strength of the engagement, e.g. to prevent unwanted separation. The magnetic engagement may also avoid mechanical connection error that can occur with conventional mechanical linkages.

Figs. 3A to 3D illustrate various stages in the assembly of the base 102. Fig. 3A shows the second magnet 138. The second magnet 138 is in the form of a disc having tapering side surfaces. The side surfaces taper towards (i.e. cause a decrease in diameter towards) the engagement interface with the first magnet 124. This direction of tapering assists in retaining the second magnet 138 within the overmoulded housing 136. Axial slots 142 are formed in the outer surface of the second magnet 138 to assist retention of the second magnet 138 in the overmoulded housing 136 in a rotational sense.

Fig. 3B shows the second magnet 138 mounted in the overmoulded housing 136. The overmoulded housing 136 forms a cup to retain the second magnet 138. The underside of the cup comprises a hole 144 for receiving the spindle of the motor. In addition, the underside of the cup is shaped to fit against an upper surface of the base in order to prevent material from leaking into the motor.

Fig. 3C shows the overmoulded housing 136 mounted on the spindle 132 via the threaded portion 140.

Fig. 3D shows an example of a fully assembled base 102. Features having the same function as those in Fig. 1 are given the same reference number. As shown in Fig. 3D, the base 102 has a top cover 150 that is mounted over the motor housing 130. The overmoulded housing 136 and second magnet 138 protrude from the top cover 150. The bottom surface of the overmoulded housing 136 is shaped (e.g. as curved portions 146, 148) to conform to the shape of the top cover.

Preferably there is a small separation between the overmoulded housing 136 and the top cover 150. The top cover may also include engagement slots 116 around its periphery to receive corresponding projections on the bottle 104.

Fig. 4 shows a cross-sectional view through the base of the bottle 104 in order to show the bottle portion of the coupling 112 in context. Features which have been described above are given the same reference number and are not

described again. The bottle 104 defines an internal volume 160 that has a bottom surface 158. The bottle portion of the coupling 112 is centrally mounted in the bottom surface 158 of the inner volume. In this example, there is an upward projection 162 in the bottom surface 158 through which the shaft 120 extends. The top cover 118 and overmoulded housing 126 are mounted on opposite ends of the shaft 120 to retain it in position in the projection 162.

The shaft 120 passes through a vessel seal 164, which is retained in an aperture formed in the projection 162. The vessel seal 164 is a moulded component (e.g. formed from silicone) that is resiliently deformable to sealingly engage around the shaft 120. The vessel seal 164 may be a top-hat section moulding which engages the shaft 120 at an upper seal point and a lower seal point, between which is defined a internal cavity 166. In use, the shaft 120 rotates relative to the vessel seal 164. The internal cavity 166 is preferably filled with hydrophobic grease to prevent leakage from the internal volume 160. The vessel seal 164 is retained in place by vessel base plug 168, which fits within and is retained (e.g. using a suitable bayonet connection or the like) under the projection 162. For example, the vessel seal 164 may comprise a radial flange 170 that is sandwiched against the underside of the vessel by the base plug.

The bottle includes a skirt 154 which extends below the bottom surface 158 to define a recess 152 that fits over the top cover 150 of the base (see Fig. 3D) . The lower volume may be shaped to assist location of the bottle on to the base. The first magnet 124 protrudes into the lower volume 152 so that it can engage the second magnet on the top of the base.

Protrusions 156 may be formed on the inside surface of the bottom peripheral edge of the recess 152. The protrusions 156 form engagement features that are arranged to fit within the engagement slots 116 formed in the top cover 150 of the base .

In use, the bottle 104 is positioned over the base 102 so that the recess 152 aligns with the top cover 150. The bottle is then lowered onto the base so that the first magnet 124 and second magnet 138 are attracted to each other to retain the bottle on the base. The bottle and base may then be rotated relative to one another in the same sense as the motor drives the mixing element to engage the projections 156 into their respective slots 116. This engagement prevents the bottle from rotating when the motor is activated.

Material to be mixed can be introduced to the internal volume 160 at the top of the vessel, and the device can be activated by pressing the button on the base.

Another embodiment of a magnetic coupling according to the invention is described below with respect to Figs. 5A, 5B, 6A, 6B and 7.

Figs. 5A and 5B are exploded and assembled view

respectively of a base coupling component 200. The base coupling component may have the same function as the component shown in Fig. 3B above, i.e. to secure a lower magnet to a motor mounted within the base of a mixer product .

The base coupling component 200 comprises a magnetic element 202, which in this embodiment is an annular magnet, e.g. comprising a ring-shaped body with a central through hole formed therein. The magnetic element 202 may be formed from ferritic stainless steel or other similarly hard-wearing (e.g. corrosion-resistant) magnetic material. The base coupling component 200 further comprises a housing 204, which may be a moulded element, e.g. formed by injection moulding or the like, having an annular recess 206 shaped to receive and retain the magnetic element 202.

The housing 204 comprises an upstanding stub, e.g. a cylindrical rod, that is shaped to fit within the central through hole of the magnetic element 202. As explained below, an upper surface stub 208 has an indention 209, such as a spherical recess or the like, that functions to align the coupling in use.

The housing 204 also comprises an undulating ridge 210 formed around the circumference of the annular recess 206. In this example, the undulating ridge provides three projections, each having an engagement surface that faces in a

circumferential direction. These projections are configured to cooperate with corresponding projection on the other part of the magnetic coupling to present a physical engagement surface to assist in transferring drive from the base unit into the vessel.

Figs. 6A and 6B are exploded and assembled view

respectively of a vessel coupling element 300 that can be used with the base coupling element 200 discussed above to form a magnetic coupling that is an embodiment of the invention. The vessel coupling element 300 comprises a rigid shaft 302 that extends into the vessel, e.g. in a similar manner to the shaft 120 discussed above. A mixing blade (not shown) may be secured to an top end of the shaft 302. The shaft 302 is preferably a non-magnetic material, e.g. austenitic stainless steel .

The vessel coupling element 300 further comprises a housing 304, which may be a moulded element, e.g. formed by injection moulding or the like. In this embodiment, the housing 304 resembles an upturned cup, comprising an annular top surface with a downward extending skirt depending from a outer circumference thereof. An aperture 308 is formed in the top surface of the housing 304. The shaft 302 is mounted in, e.g. secured or affixed within, the aperture so that it does not move relative to the housing 304. The housing 302 may be moulded around the shaft 302.

The vessel coupling element 300 further comprises magnetic element 306, which in this example is an annular magnet 306, e.g. comprising a ring-shaped body with a central through hole formed therein. The magnetic element 306 may be formed from neodymium or other material with high magnetic attraction .

A lower end of the shaft 302 is arranged to protrude within an interior volume of the housing 304. The central through hole of the magnetic element 306 and the diameter of the shaft 302 cooperate so that the magnetic sits within the interior volume between an inner wall of the skirt and the shaft .

The housing 304 comprises an undulating ridge 310 formed around the bottom edge of the skirt. As explained above, the undulating ridge is arranged to cooperate with a corresponding feature of the base coupling component. Accordingly, in this example the undulating ridge provides three projections, each having an engagement surface that faces in a circumferential direction. However, it is to be understood that any

interengaging features that act to transfer drive rotation could be used for the undulating ridge.

Fig. 7 shows a schematic cross-sectional view of a magnetic coupling 400 that is formed when the base coupling component 200 and the vessel coupling component 300 mate with one another. Features in common with Figs. 5A, 5B, 6A and 6B are given the same reference number and are not described again .

During the mating operation, a lower end of the shaft 302 is drawn into the recess 209 in the housing 204 as the base magnetic element 202 attracts the vessel magnetic element 306. This arrangement ensures that the vessel coupling component is drawn and aligned to the base coupling component such that the only point of contact before a rotational drive force is applied occurs between the shaft 302 and the recess 209. The rotational drive force can therefore be transmitted without the risk of damage or heating due to frictional forces between the magnets. In this arrangement the magnetic elements 202, 306 are not in physical contact during operation.

The length of the shaft 302 that protrudes from the underside of the housing 304 may be selected to prevent the axially opposing surface of the undulating ridge from

contacting one another. As the rotational drive is applying the undulating surface may make physical contact in the drive direction, i.e. circumferentially .

The profile of the bottom end of the shaft 302 and the recess 209 may be shaped to allow the vessel coupling

component 300 to be capable of transferring drive even when lying at an angle, e.g. of up to 2 degrees, relative to the base coupling component 200.

The shaft 302 may be supported on the vessel (not shown) itself via a bushing 402. The bushing 402 may be an moulded component that is secured to or formed with the vessel. When the shaft 302 is held by the bushing 402 and retaining in the recess 209, drive can be transferred with little to no vibration about the shaft.