TECHNICAL FIELD

The present invention relates to an ice-cream machine of the kind set forth in the preamble of claim 1.

BACKGROUND ART

Ice-cream machines of this kind are known, cf. e.g. U.S. patent publication No. 4,755,060, in which the bottom plate in the mixing cone has a number of apertures cooperating with the rotating knife in comminuting hard particles, e.g. pieces of frozen fruit, nuts or candies, that have been added to the ice-cream mass proper before the latter is processed in the machine. In these known machines, however, the apertures in the bottom plate are placed and extend in such a manner, that "dead annular zones" are formed, in which the knife blades during their rotation at no instant cooperate with an aperture. The result of this fact is that the ice mass will have a longer time of residence in the mixing cone than strictly necessary, and because of the unavoidable stirring effect and consequent production of heat, the ice mass will in many cases be heated to an unfavourably high temperature.

DISCLOSURE OF THE INVENTION

It is the object of the present invention to provide an ice-cream machine of the kind initially referred to, that does not suffer from the inconvenience referred to above, and this object is achieved with an ice-cream machine, according to the present invention

additionally exhibiting the features set forth in the characterising clause of claim 1. With this arrangement, the "dead annular zones" referred to are substantially avoided together with the consequent and unnecessary stirring and heating of the ice mass, so that the latter may leave the mixing cone at a lower temperature than has hitherto been considered possible.

Advantageous embodiments of the ice-cream machine according to the present invention, the effects of which are explained in more detail in the following detailed portion of the present specification, are set forth in claims 2-7. Here, only the embodiment referred to in claim 7 is to be mentioned, as it increases the efficiency of the partial process, during which the ice mass is pressed out of the mixing cone by means of the auger, and hence a corresponding energy saving and reduction of the production of heat.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed specification, the present invention will be explained in more detail with reference to the drawings, in which

Figure 1 shows the ice-cream machine in side elevation and with the machine covers removed,

Figure 2 shows the machine in front elevation and with the machine covers in place,

Figures 3-5 show the mixing auger and the mixing cone with the latter in three different height positions,

Figure 6 is a sectional view on a larger scale through the lowermost end of the mixing cone, the latter's bottom plate and the securing means for the bottom plate,

Figure 7 shows the bottom plate of the mixing cone, seen from above and in two different vertical sectional views,

Figure 8 shows the mixing auger on an enlarged scale, seen in elevation, and

Figure 9 on the same scale as Figure 8 shows the knife belonging to the mixing auger and adapted for comminuting hard particles, seen in elevation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The exemplary embodiment of an ice-cream machine according to the present invention shown in the drawing comprises the following active working members: a funnel-shaped mixing cone 21, the bottom of which, cf. especially Figures 6 and 7, is constituted by an upwardly plane bottom plate 21a, in which is shaped an aperture 21b, through which the material having been processed can flow ^~ a mixing auger 17, adapted to rotate when in operation, the external contour of which fits with the inside of the cone 21, and which at its lower end carries a knife 18 that may move axially but not rotationally relative to the auger 17, said knife 18 as shown in the example of Figure 9 comprising four radially protruding knife blades 18a adapted to cooperate with the aperture 21b in

the bottom plate 21a, said knife 18 possibly also being spring loaded downwardly, a "cone elevator" or sliding carriage 20, which gliding on vertical columns 19 may be elevated to the operating positions shown in Figures 4 and 5, in which the inside of the cone 21 is close to or contacts the outside of the convolutions on the auger 17 respectively, and - various operating means, control means, drive means and motor means, with which the movements of the auger 17 and the cup 21 may be carried out and controlled to achieve the desired operating functions.

The cone 21 may be permantly secured to the carriage 20, but is preferably removably positioned and guided in the carriage in such a manner, that the cone is held precisely coaxially with the auger 17. Likewise, the auger 17 may be permanently secured to its drive shaft 17a, but is preferably secured to the latter by means of a quick-acting coupling 16.

The auger 17 is preferably made of a not quite hard plastic material. In this manner, it is achieved in the operating position shown in Figure 5 that the auger wipes the material from the inside of the cone 21 and hence empties the latter in a more effective manner than has been possible with the previously used metal augers. A similar effect may be achieved by using a mixing cone 21 of plastic material, in which case the auger 17 may consist of metal, but in this case there is a greater risk that material will be abraded from the inside of the cone and hence contaminate the material being processed.

The sliding carriage 20 is secured to one end of a long chain 4, the other end of which as shown is anchored to the machine frame at a relatively high point. From the carriage 20, the chain 4 first passes over a sprocket 8 supported rotatably about a stationary axis in the machine frame, and from there below a sprocket 5 being rotatably supported on the movable part of an electrically driven linear motor, e.g. a so-called screw-and-nut motor 2, secured in the machine frame, finally ending in its anchorage point, as mentioned high up in the machine frame. When the linear motor 2 is actuated from the position shown in Figure 1, the sprocket 5 moves downward, causing the carriage 20 with the mixing cone 21 to be elevated with a speed twice as high. During the downward movement, the sprocket 5 or a member connected thereto passes and activates a number of switches 9-12 on a switch panel 13 secured to the machine frame. The switch 9, being placed uppermost, constitutes the uppermost end stop for the sprocket 5, i.e. the lowermost end stop for the carriage 20 with the mixing cone 21, whilst the switch 12 is the lowermost end stop for the sprocket 5 and hence the uppermost end stop for the mixing cone 21.

The intermediate switches 10 and 11 will during the downward movement of the sprocket 5, i.e. the upward movement of the mixing cone 21, firstly cause the auger 17, for this purpose being driven by a main motor 1, to be started, and the upward movement of the mixing cone to be stopped temporarily so as to make it possible for the auger 17 to mix the material having been introduced into the mixing cone, cf. Figure 4, before the mixing cone is moved to the final dispensing position shown in Figure 5.

In the example shown, the movable part of the linear motor 2 is guided by a guide rail 30 secured in the machine frame.

Both the main motor 1 and the various switches 9-12 referred to are preferably connected to a control box 3 containing the requisite connections, relays including any semiconductor means - and fuses, the control box 3 also being adapted to receive control signals from an operating panel 22 situated uppermost on the front side of the machine facing towards the right in Figure 1, said panel 22 inter alia comprising a main switch 23, a starting switch 24, an error alarm lamp 25, an emergency stop 26, and a stop 27. The control box 3 is also adapted to deliver information or alarm signals, e.g. to said error alarm lamp 25 and/or an alarm bell (not shown) or the like.

Apart from the means and functions described, relating to the normal operation of the ice-cream machine, the control box 3 is also adapted to receive signals from a rinsing switch 29 placed lowermost and to the right in Figure 2, and in dependence thereof to execute a rinsing operation comprising that the mixing cone 21 in its highest position, in which it, cf. Figure 5, is in intimate contact with the auger 17, or possibly in the somewhat lower position shown in Figure 4 is closed upwardly by a closure plate 15, after which a rinsing-water stream through a pair of rinsing tubes 14 is directed through the mixing cone, preferably whilst the auger 17 is rotating. If so desired, the rinsing operation may be followed by hot air or steam being blown through the parts in question in order to remove rinsing-water residue and/or to sterilize the

active surfaces on the auger 17 and the mixing cone 21.

A quick-acting coupling 6 is adapted to connect the ice-cream machine with a rinsing-liquid source, e.g. the local waterworks - provided, of course, that the public-health regulations are adhered to. A V-belt 7 transmits the driving power from the main motor 1 to the auger 17. The safety shield 28 shown in Figure 2 protects the operating personnel against involuntary contact with the auger 17 and the knife 18, and is in a manner known, but not shown, mechanically connected to a safety switch adapted to interrupt the operation of the machine, when the shield 28 is removed.

As is evident from Figures 6, 7 and 9, the aperture 21b in the bottom plate 21a is shaped like "a star¬ fish with six arms", each arm of which extends all the way out to the transition from the inside of the cone 21 to the upper side of the bottom plate 21a, whilst the knife 18 consists of four radially directed knife blades 18a, the radial length of which generally correspond to the radial extent of each arm in the aperture 21b.

Because each arm in the aperture 21b and each knife blade 18a on the knife 18 extends substantially all the way out to the inside of the mixing cup 21 in the latter's lowermost part, hard particles, such as lumps of frozen fruit, nuts and the like, will be subjected to a shearing action as soon as they hit the bottom plate 21a, in contrast to the situation in previously known machines of this kind, in which the apertures in the bottom plate had a limited radial extent, so that "dead annular zones" were created, in which the knife

blades theoretically seen could go on pushing the hard particles around and around on the bottom plate, without the particles coming into engagement with the aperture or apertures in the latter. When considering that the stirring effect caused by the auger 17 and the knife 18 with its knife blades 18a on the mass of ice (not shown) placed in the mixing cup, unavoidably causes heating of the mass of ice, it will be obvious that the period of residence in the mixing cup 21 should be as short as possible. With the special shape of the aperture 21b as provided by the present invention, the "dead annular zones" are avoided, as each and every hard particle hitting the upper side of the bottom plate 21a will immmediately be caught by the next knife blade 18a and carried along to that arm of the aperture 21b nearest in the direction of rotation, in which arm the first shearing of the particle occurs, the particle during the ensuing passage across the remaining arms in the aperture 21b gradually being completely comminuted and accompanying the remainder of the mass of ice downwards through the aperture, forming a profiled extrudate, cf. Figure 5.

As evident from Figures 7 and 9, the knife 18 has a smaller number, viz. four, knife blades 18a than the number, viz. six, of arms in the aperture 21b in the bottom plate 21a. In this manner, it is avoided that all the knife blades 18a at the same time cooperate with a corresponding number of arms in the aperture 21b, which in the worst possible case - hard particles in engagement in front of all knife blades - could lead to a very high load on the knife 18 and at least to strong vibrations, if the number of hard particles in the mass of ice is relatively large. A similar effect would, of course, be achieved by having a

greater number of knife blades than arms in the aperture, but with the arrangement shown, better strength relationsship are achieved. By having both the number of knife blades 18a and the number of arras in the aperture 21b as even numbers it is achieved that the force of reaction on the knife 18 becomes more symmetrical than would be the case with an odd number of knife blades and aperture arms respectively.

As evident from the sectional view to the right in Figure 7, the side surfaces 21c and 21d in the arms in the aperture 21b may extend at an oblique angle downwardly and away from each other. If the auger 17 and hence the knife 18 with the knife blades 18a in a "normal" manner rotates "with the sun", i.e. clockwise when viewed from above, the knife edges 18b on the knife blades 18a will when the latter rotate cooperate with the uppermost edges of the side surfaces 21c in a similar manner as in a pair of scissors. Here, it has proved advantageous to let at least the side surfaces 21c extend at an oblique angle as shown, as this improves the shearing effect and reduces the production of heat. When the opposite side surfaces 21d also extend obliquely in a similar manner, this is in part due to the production process, in which two oppositely situated arms are shaped simultaneously, such as by a milling process, in part that experience has shown that this divergence of the side surfaces, especially in cooperation with a corresponding divergence of the end surfaces 21e in the arms, and the downwardly convex shape of the lower side 21f of the bottom plate 21a provide highly advantageous outflow conditions for that "snake" of ice mass being extruded through the aperture 21b.

The bottom plate 21a is preferably releasably secured to the lower side of the mixing cone 21, e.g. as shown in Figure 6 by means of a union nut 21g.

It is not shown in the drawing how the knife 18 is connected to the auger 17 in such a manner, that the knife may move axially, possibly under a spring load, relative to the auger, but not turn relative to the latter. It does however, lie within the normal scope of work for a skilled mechanic to devise a mutual construction and arrangement of the two members, suitable for this purpose. A known possibility has already been indicated in the US patent publication No. 4,755,060 referred to initially.