AUTOMATIC BEVERAGE DISPENSER, COMPRISING ELECTROMAGNETICALLY OPERATED MIXING MEANS

Abstract: The invention provides an automatic beverage dispensor, e.g. for mixing coffee powder with hot water, which is compact and permits easy and thorough cleaning of the stirrer (2,12) and housing (1) therefore and wherein the drive means (7,8,9) for the stirrer, (2,12) being electromagnetic, do not include a drive shaft, connected to a motor, so that said drive means may be left stationary in the dispenser during cleaning. Also there are no sealing problems between drive means and stirrer housing.

Description: The invention relates to a mixing device for use in an automatic beverage dispenser, comprising a mixing reservoir provided with supply openings for a liquid and for a material to be mixed therewith and having at its lower end an outlet opening which leads to a stirrer housing provided with a discharge sprout, a stirrer means being placed for movement with said stirrer housing with its axis coincident with the vertical axis of said housing. Such a mixing device is known from DE-A-2 401 001. In this well-known device the stirrer means is fastened to the lower end of a drive shaft of an electromotor, the latter being mounted on a bracket fixed to the stirrer housing in a position above the stirrer housing and with its drive shaft extending downwardly through a cover on top of the stirrer housing. For cleaning purposes, the bracket may be detached and removed together with the drive motor and the stirrer means, provided that the cover is simultaneously removed. Due to the stirrer means being connected to the drive motor and its electrical terminals, cleaning of the stirrer is rather onerous and time-consuming. Moreover, due to the presence of a drive motor on top of the stirrer housing, the well-known dispenser is lacking compactness. The present invention aims at remedying the above inconveniences. According to the invention this aim is achieved in that the stirrer means is independently removable and lies within the field of an electromagnet positioned outside and adjacent the stirrer housing, the stirrer means being movable in response to the electromagnetic field. As a consequence of the features of the invention the electric drive motor of the well-known device is eliminated, so that the stirrer means has become a separate part which may be simply placed or hung into the stirrer housing and may be simply removed for and replaced after cleaning. It is to be noted, that magnetic stirrer or activator apparatus are known per se. In this connection reference is made to EP-A-0 127 970, disclosing an apparatus for stirring culture mediums, comprising a vessel in which a floating stirrer, associated with a magnet, is caused by a moving magnetic field to rotate about a vertical supporting spindle, the field generating means being located laterally of said vessel. GB-A-2 069 355 discloses a vibratory agitation apparatus, in which an agitator within an oil bath vessel comprises a permanent magnet resiliently suspended from a fixed point of the vessel and interacting with a magnetic field by an electromagnet mounted beneath the oil bath. Apart from these well-known apparatus being designed for different purposes, the stirrer (agitator) in these apparatus is quite obviously not mounted for a quick removal for and replacementt after cleaning. Practical and/or preferred embodiments of the present invention are defined in the sub-claims. The invention will hereunder be further explained with reference to the drawing in which embodiments of the mixing device according to the invention are shown. Fig. 1 is a perspective view of a mixing device according to the present invention. Fig. 2 is a perspective view of an electromagnet, adapted to be mounted around the lower part of the device of fig. 1. Fig. 3 is a schematic vertical section with over it a plan view of the embodiment having a squirrel cage rotor. Fig. 4 shows schematically in the same manner as fig. 3 the embodiment with translatory mixing fin. Fig. 5 shows in the same manner as figures 3 and 4 the embodiment with alternately twisting mixing fin. Fig. 6 shows a further embodiment with alternating rotation of the mixing fin. In the embodiment of the mixing device according to the invention, schematically shown in fig. 1, the stirrer is a mixing fin having a permanent magnet positioned perpendicular to the electromagnet field. The mixing beaker is integrally formed with the stirrer housing 1b. The mixing fin 2 is provided within the stirrer housing 1b and comprises an elongate flat part 2a in which, at its lower end, a permanent magnet 3 is incorporated. At its upper end the mixing fin is laterally extended into two ears 4 which are hung in slit-shaped recesses 5 in the wall of the mixing beaker 1a, said slits opening into the upper edge of the mixing beaker, so that the mixing fin may be entered through said slots into the stirrer housing and may be taken therefrom. In fig. 5, which relates to the same embodiment, the north pole portion of the permanent magnet 3 has been shown hatched and the south pole portion without hatching. In certain cases it may be preferable to provide in the centre of the mixing fin perpendicular to its plane transverse ridges 6 as reinforcements. Fig. 2 shows an electromagnet having a wire coil 7, the ends 7a, 7b of which are connectable to an alternating current source. The transverse beam of a U-shaped armature 8 is provided within the coil 7 and the armature comprises a stack of weak-iron sheets, at the free ends provided with pole shoes 9. Through conductors (not shown) provided on a frame of the automatic beverage dispenser, the stirrer housing 1b may be placed centrally between the pole shoes 9, as indicated by the broken line circle 10 in fig. 2. The conductors are such that the centre of the permanent magnet 3, which may also be differently shaped from the cylinder shape shown, is in the common axis of the pole shoes 9. If now the alternating field is connected to 7a en 7b, the poles at the end of the pole shoes 9 will become alternately the north pole and the south pole of the electromagnet field, so that the north pole side of the permanent magnet 3 is alternately attracted and rejected by both field poles, as well as the south pole side of the permanent magnet. The mixing fin 2 is manufactured from a resilient non-magnetic material, e.g. silicone rubber. The alternate attraction and rejection of the permanent magnet cause alternate twisting in two directions around the mixing fin axis as shown with the double arrow in fig. 5. Liquid supplied to the top of the mixing beaker is now stirred by the alternate mixing fin movement and mixed and discharged at the lower end of the stirrer housing 1b through a conduit connected to a pivotable discharge sprout e.g. into a beaker placed below that sprout. Fig. 4 shows a different embodiment of the device which corresponds to fig. 5 apart from the fact that the plane of the mixing fin 2 now lies perpendicular to the field direction of the electromagnet field. Thereby the fin will carry out a translatory or vibrating alternate movement according to the axis of the pole shoes 9 as the current is switched on. In this case the mixing fin 2 is not provided with a reinforcement ridge 6. This can also be omitted in the embodiments according to figures 2a and 5 or be differently shaped, dependent on the material of the fin. In fig. 6 a very advantageous modification of the embodiment of fig. 5 is shown. For it is that the twisting of the fin according to this figure 5 is maximum at the position of the magnet 3 and decreases towards the upper end of the spring whereby also the mixing effect decreases. According to figure 6 the fin is connected at its upper end to a transverse strip 14 of preferably silicone rubber, which strip is fixed with its ends relative to the mixing beaker 1. This is here obtained by providing the strip as a diametral part of a ring 15 of the same material, which ring is to be placed somewhat clampingly in the lower end of the mixing beaker, e.g. but not necessarily in a recessed portion thereof. In this embodiment the mixing beaker and the stirrer housing form again two parts, wherein a cylindrical discharge end of the mixing beaker is placed within the ring 15 and with recesses (not shown) in its edge around the strip 14. The stirrer housing 17 has an integral discharge knee piece 18, which may be placed in a desired direction within the housing of the automatic beverage dispenser (not shown) in that the relative position between knee 18 and ring 15 may be freely selected. In the embodiments of figures 4 and 5 the knee piece (not shown) is a separate part relative to the housing 1 because the fin is fixedly positioned in angular position in the housing so that the angular position of the housing depends on the field direction of the electromagnet 7, 8, 9. In order to prevent engagement between the lower end of the fin 2 and the housing wall, which would hinder the movement and cause noise, this end is fixed through a pin 16 relative to the wall of the knee piece (fin is liftable). For preventing that the flow to be mixed and flowing along the bottom of the mixing beaker 1 downwardly enters the mixing beaker 1, the bottom of the beaker 1 may be extended by a so-called splash rim 19. For it is that the strip 14 and the stirrer 2 move the liquid strongly laterally and upwardly at that location. Finally fig. 3 shows a further embodiment in which the stirrer comprises a hollow rotor 12, which is received within the cylindrical lower part 1b, which represents the trirrer housing. This mixing rotor receives in the manner of an electric squirrel cage motor a cage comprising bars extending parallel to the housing axis and manufactured of a conductive metal. If now the field of the electromagnet is energized, the rotor starts turning and carries out the mixing operation. It is advantageous therewith to provide a so-called starting coil, because otherwise the rotor does not start moving. A fin 13 having a cross-shaped section is provided within the hollow rotor into which the liquid is supplied from the mixing beaker 1a, said cross-shaped fin serving for producing the necessary mixing effect. As has been said above already, the lower part of the mixing fins according to figures 2a, 4 and 5 may have a lateral dimension equal to the largest lateral dimension of the permanent magnet and the lower housing portion 1b directly over the magnet may be widened to about the diameter of the upper part 1a of the housing, if necessary, extending gradually or conically thereto. The portion of the mixing fin between the upper supporting end and the magnet 3 thereby may be widened and e.g. provided with vertical slots whereby said portion produces a so-called whisk-effect. Thereby the poleshoe ends may be approached towards the permanent magnet 3, so that the air gap becomes smaller and thereby the attraction force of the electromagnet becomes greater. The mixing device as described is suitable for mixing powdered material, such as milk powder, cocoa powder, sugar and soup-powder with liquids, such as coffee, tea and hot water. Of course also different mixtures are possible.

Claims: 1. A mixing device for use in an automatic beverage dispenser, comprising a mixing reservoir provided with supply openings for a liquid and for a material to be mixed therewith and having at its lower end an outlet opening which leads to a stirrer housing provided with a discharge sprout, a stirrer means being placed for movement within said stirrer housing with its axis coincident with the vertical axis of said housing, characterized in that the stirrer means is independently removable and lies within the field of an electromagnet positioned outside and adjacent the stirrer housing, the stirrer means being movable in response to the electromagnetic field. 2. A device according to claim 1, characterized in that the stirrer means is formed as of a rotor (12), in which a metallic squirrel cage is incorporated. 3. A device according to claim 2, characterized in that the rotor (12) is loosely supported on a thrust journal (16) in the housing (1b) and in that the centre of the cage is situated, as viewed in the vertical direction, somewhat below the centre of the electromagnet field when the electromagnet (7-9) is not energized. 4. A device according to claim 1, characterized in that the stirrer means is shaped as a mixing fin (2), in the axis of which a permanent magnet (3) is incorporated, the field direction of which is parallel to the field of the electromagnet (7-9). 5. A device according to claim 1, characterized in that the stirrer is shaped as a mixing fin (2) and a permanent magnet (3) is incorporated in its axis, the field direction of which is perpendicular to the field of the electromagnet (7-9). 6. A device according to claim 5, characterized in that the mixing fin (2) is connected at its upper end to a strip (4) of resilient material, e.g. silicone rubber and extending transversely to the fin axis (fig. 5). 7. A device according to claim 6, characterized in that the strip (4) of resilient material extends along a diameter of a ring and is integral therewith. 8. A device according to claim 7, characterized in that the ring is adapted to be sealingly placed between the mixing reservoir (1a) and the stirrer housing (1b). 9. A device according to one or more of the preceding claims, characterized in that the mixing reservoir (1a) and the stirrer housing (1b) are formed in one piece. 10. A device according to one or more of the claims 4-8, characterized in that the permanent magnet (3) is provided in a lower portion of the mixing fin (2) having a smaller transverse dimension than the upper portion of the mixing fin. 11. A device according to any of the claims 4-10, characterized in that a portion of the mixing fin (2) is provided with slots, such that a whisk effect is produced.

Inventors: EVERS, LUCAS ALPHONSUS MARIA, VAN REEUWIJK, WILLEM
Applicants: KONINKLIJKE OLLAND INDUSTRIE EN HANDELMIJ B.V.
Application year: 1988
Main classification: B67D3
IPC codes: A47J31, B01F13, B67D1, B67D3