Abstract:
The invention relates to a device for the discontinuous production of ice-cream from a liquid mixture. Said device comprises a processing container, in which at least one tool is mounted so that it can rotate and repeatedly apply the liquid mixture to and scrape the latter from the refrigerated interior wall of the processing container, a fill opening for the liquid mixture and a discharge opening for dispensing the ice-cream from the processing container. The longitudinal axis (L-L) of the processing container ( 10 ) is inclined at a first acute angle (α) in relation to the horizontal (H) and the rotating tool ( 20 ) comprises spatulas which are configured and mounted in such a way that they continuously transport the ice-cream mass which forms to the discharge opening ( 15 ), lying at the lowest point of the processing container ( 10 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a device in accordance with the preamble of claim  1 , as well as to a method for producing ice cream by means of this device. The known machinery for producing ice cream is employed in connection with commercial ice cream production, for example in ice cream parlors. 
     The basic principle is the same with all machines: the liquid mixture in the processing container is partially and repeatedly applied to the cooled wall of the processing container by means of a processing tool, is cooled there, frozen, and scraped off again and returned to the not yet frozen liquid mixture; once the entire amount of the liquid mixture has frozen into an ice cream mass of the desired consistency and quality, it is taken from the processing container. 
     PRIOR ART 
     A differentiation is made in connection with the known discontinuously operating machines between those which are equipped with a rotating vertical vat with cooled wall surfaces, from which the finished ice cream must be removed by means of a large spatula, and those which have a horizontally placed vat and expel the finished ice cream by means of a processing tool. 
     DE-U-84 38 146.9 discloses a representative of the first mentioned type with the typical disadvantages: filling and emptying take place from the top of the processing container, which is slightly inclined in respect to the vertical direction, a trained specialist is required for removing the finished ice cream with the spatula, since it is dangerous to remove ice cream from the rotating vat. Characteristic for vertically operating machine are the continuous monitoring of the production process by freezing and extended production times; processing the ice cream and cleaning the vat with hands and lower arms in the very cold moist area leads to known health risks; the advantage of this classic machine type rests in a well-kneaded structure and a very low temperature of the finished ice cream. 
     Therefore there has been no lack of attempts to achieve a similarly good ice cream quality by means of different structural principles: 
     DE-OS 33 07 016 discloses a device in accordance with the species, wherein the processing container is horizontally arranged, with this device the longitudinal axis of the cylindrical container I extends horizontally. The manipulating end of the device is closed off by a cover, in which a filling funnel for introducing the liquid mixture and a removal opening for removing the finished ice cream are located. The tools for processing the liquid mixture are embodied in several parts: a rotating element is used for coating the wall of the processing container with the liquid mixture, an also rotating kneading and ejecting element, which additionally moves axially back and forth in the longitudinal axis of the processing container, is used for kneading the ice cream mass being formed by means of scraping elements, for the permanent scraping off of the liquid mixture applied to the inner wall, and finally for ejecting the finished ice cream through the removal opening. 
     With this machine with the horizontal processing container, processing of the liquid mixture is performed at a low number of revolutions, for ejecting the finished ice cream the number of revolutions is increased in order to speed up this process and to prevent thawing effects. However, ice cream of unsatisfactory quality is produced with this device since, because of the narrow diameter of the processing container and the comparatively quite high rotational speed it has little time to freeze on the wall of the processing container, with this machine it must not freeze too solidly in order to still convey the ice cream out from the rear to the front through the removal opening of the processing vat at a high number of revolutions by means of the ejection element. 
     Because of the high ejection speed and the narrow cross section of the removal opening, frictional heat is conveyed to the frozen mass of ice cream, which heats the ice cream mass and begins to degrade the structure and the texture of the ice cream; emptying of the processing container is only incomplete. Finally the structure of the device in accordance with the species is very expensive in comparison with the not completely satisfactory results. 
     EP 0 495 211 A1, which defines the species, discloses a multi-purpose device which can also be used for the discontinuous preparation of ice cream, wherein the processing container is horizontally arranged. At the manipulation end, the device is closed by means of a cover in which a filling funnel for introducing the liquid mixture and a closeable removal opening for taking out the finished ice cream are located. The tools for processing the liquid mixture consist of an agitator with three spatulas. Because of their construction with many components, the known ice cream machines require a large cleaning outlay, since many joints, open edges and seals (for example a fixedly attached run-off plate) exist, which come into direct contact with the ice cream. They therefore constitute a good culture medium for dangerous bacteria, for example salmonella. For this reason the known machines are questionable in regard to sanitation, since the required outlay for cleaning, even if it can be performed at all, is not always applied for lack of time. The employment of suitable chemicals for cleaning is not desirable for sanitary and ecological reasons. The reception of the finished ice cream following the delivery from the removal opening is also not satisfactorily solved in connection with the known machines. 
     Most commercially available customary ice cream machines only have a vat receptacle, on which the vat is placed loosely (the bottoms of ice cream vats are always curved), and in most cases too low, on an unsanitary rubber support; one hand is always needed to fix the vat in a position suitable for introducing the finished ice cream, and to maintain it there. These work processes are arduous and endanger the health of the operators. 
     No manufacturer offers a practical solution at this time in regard to the coarse additives, which are added to certain types of ice cream during their removal. 
     DESCRIPTION OF THE INVENTION 
     It is the object of the invention to further develop the device in accordance with the invention in such a way that an improvement of the quality of the ice cream can be achieved. In accordance with the invention, this object is attained by means of the characteristics of claim  1 . 
     The basic concept of the invention consists in the combined effect of the inclination of the processing container and of the tools, which operate exclusively in a rotating manner and therefore can be employed for processing the liquid mixture into ice cream, as well as for ejecting the finished ice cream. 
     Advantageous embodiments of the attainment of the object in accordance with the invention can be taken from the dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred exemplary embodiment of the device in accordance with the invention will now be explained in greater detail by means of the drawings, shown are in: 
     FIG.  1 : a schematic longitudinal section through the device, 
     FIG.  2 : a partially cut, perspective representation of the processing container of the device, 
     FIG.  3 : a partial perspective view of a spatula in the processing container, 
     FIGS. 4A to  4 C: longitudinal sections through the processing container in the course of various processing stages, 
     FIG.  5 : a perspective representation of the funnel and its closure element, 
     FIG.  6 : a perspective representation of the removal opening and its closure element. 
    
    
     DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENT 
     FIG. 1 shows the essential components of a device for producing ice cream in accordance with the invention; a processing container  10 , preferably made of special steel, is maintained, preferably welded, in a housing  40  in such a way that its longitudinal axis L-L forms an acute angle α. of approximately 20° with a horizontal line. A tool  20 , whose driveshaft  25  is connected by means of a belt drive  32  with the motor shaft  31  of a motor  30 , rotates around the longitudinal axis L-L inside this cylindrical processing container  10 . In the exemplary embodiment represented, the belt drive  32  causes a reduction of the number of revolutions of the motor, approximately at a ratio 1 to 5. 
     The tool  20  can be inserted into the driveshaft  25  from the direction of the open side of the processing container  10  and can be easily removed, for example for cleaning purposes. 
     A front plate  43 , through which all switching devices of the device are accessible, is located underneath the processing container  10  at the front of the housing  40 . 
     The switching devices are housed in a switchbox  46 , from where control and supply cables  47  are distributed to the corresponding components inside the housing  40 . The switchbox  46  is maintained on the inside of the front plate  43 , which can be pivoted forward (two-headed arrow PP in FIG.  1 ). In this way the switchbox  46  is easily accessible for repair or inspection purposes. A safety chain (not represented) limits the opening angle of the front plate  43  to a maximum of 90°. It is then also possible, if needed, to unhinge the front plate  43  and place it on the floor, together with the switchbox  46 . 
     The processing container  10  is enclosed in a cooling arrangement consisting of cooling coils  11  and an insulation  12  extending over them, as schematically represented in the drawing figures. 
     A device for charging the outer wall of the processing container  10  with heating gas for cleaning purposes is provided, as well as at least one injection nozzle  41  into the processing container  10  for injecting a cleaning fluid from a line  42  into the interior of the processing container  10 . 
     The downward pointing open side of the processing container  10  can be closed off by means of a self-clamping cover  13 . A removal opening  15  has been cut into the lower end of the cover  13 , and a fill opening  14  into its upper area. A rotation of the tool  20  is only possible with the cover  13  closed and the fill opening  14  closed, since otherwise the electrical current supply of the motor  30  is blocked by a contact element. By means of this it is assured that manual access into the processing container  10  can only take place when the tool  20  is stopped. 
     An emergency stop switch  44  is arranged as an additional safety element in the lower front plate  43 , which forms the front panel of the housing  40 , which inactivates the motor  30  if operational malfunctions, which require a rapid intervention, are detected by the operators. In order to increase the speed and dependability of reaction, a trigger strap  45  extends horizontally above the emergency stop switch  44  over the entire width of the front plate  43 , so that the trigger strap  45 , which is located at knee height, can be rapidly actuated in every work position. 
     A funnel  14 A for introducing the liquid mixture to be frozen is provided in the fill opening  14 . The funnel  14 A is preferably welded on and therefore constitutes an integral part of the cover  13 . A plug  14 B, which is introduced by means of a funnel cover  14 C into the funnel  14 A, is used as the closure element of the funnel  14 A, and in this way blocks the fill opening  14  by clamping (FIG.  5 ). A container  14 D for ingredients is maintained next to the funnel  14 A and is used for receiving, for example, chocolate sprinkles, cracknel, or the like. 
     The removal opening  15  can be closed off with the closure element  15 A represented in FIG. 6 and, for safety reasons, has the customary shutter-like grid  15 D in its cross section, through which the finished frozen ice cream is delivered to the exterior. The closure element  15 A for the removal opening  15  consists of a closure plate  15 B with a toggle fastener  15 C, represented in an exploded view in FIG.  6 . 
     In the exemplary embodiment represented, wherein the processing container  10  has a diameter of approximately 30 cm, the cross section of the removal opening  15  is approximately 150 cm 2 , a value which lies considerably above the values so far used in devices of the prior art, and which makes an essential contribution to the increase of the quality of the ice cream. 
     Two parallel support arms  41 ,  42  are maintained below the removal opening  15  at adjustable distances, between which a receiving container  50  for the finished ice cream can be inserted (FIG.  4 C). 
     Moreover, a removable delivery plate  19  with laterally raised splatter protection plates is provided between the removal opening  15  and the receiving container  50  (FIGS.  4 C and  6 ). In the inserted state, the delivery plate  19  also provides a securing for the front plate  43 . 
     In the exemplary embodiment represented, the tool  20  consists of three spatulas  21 ,  22  and  23  embodied in a U-shape, which are offset in respect to each other by a circumferential angle τ=120°, so that the spatial structure represented in FIG. 2 is created. While the bases of the spatulas  21  . . .  23  are maintained on the extension (not represented) of the driveshaft  25  in the interior of the processing container  10 , the spatulas themselves are turned in such a way that their respective front faces  21 C,  22 C,  23 C form a second acute angle β with a generating line M—M (FIG. 2) extending parallel with the longitudinal axis L-L. 
     The detailed structure of the spatulas can be taken from FIG.  3 . 
     The end of the spatula  21 , represented there by way of example (with a correspondingly identical design of the other two spatulas  22  and  23 ), which faces the inner surface of the processing container  10 , is embodied to be plate-shaped, wherein two channels  21 D,  21 E have been cut into the front face  21 C, each of which terminates in an associated lateral opening  21 F,  21 G. A stripper  21 A,  21 B can be placed into each one of these channels  21 D,  21 E, so that a radial displacement of these strippers  21 A,  21 B in relation to the processing container  10  can take place by the effect of springs  21 H . . .  21 K, i.e. the strippers are pressed against the inner wall of the processing container. 
     In this case the lower end of the strippers  21 A . . . is embodied to be fork-shaped in such a way that the leg pointing toward the respective opening  21 F is accessible from the exterior, so that by means of an action on this leg the removal of the strippers out of their associated shaft, for example for cleaning purposes or for replacing defective parts, can be performed very simply and rapidly by means of the solution of the invention. 
     The mode of operation of the device of the invention will now first be represented by means of FIGS. 4A to  4 C: 
     For introducing a fluid mixture  60 , which was prepared in accordance with the properties of the resulting ice cream, the intended amount of the liquid mixture  60  is introduced into the funnel  14 A, which is represented in FIG. 4A (arrow P 1 ). During the filling process the spatulas  21  . . .  23  are stationary because of the removed cover  13 . A level of the liquid mixture  60  as approximately represented in FIG. 4A, results in the processing container  10 . After the complete introduction of the liquid mixture  60 , the fill opening  14  is closed by means of the plug  14 B. 
     The processing of the liquid mixture  60  into an ice cream mass  70  now starts, as schematically represented in FIG.  4 B: with the spatulas  21  . . .  23  rotating (rotation arrow P 2 ) at a relatively low rotary speed of 143 rpm, the spatula surfaces pick up the liquid mixture  60  and spread portions thereof on the cooled inner surface of the processing container  10 , to which the liquid mixture freezes and forms frozen surfaces  70 ′, which are also shown in dotted lines in FIG.  4 B. With each rotation of the tool with the spatulas with the integrated strippers, these frozen-on sections  70 ′ of the ice cream mass  70  are successively removed again from the inner surface of the processing container  10  and in this way get back into the not yet frozen mass of the liquid mixture  60 , so that in the length of the processing time the liquid mixture  60  is increasingly converted into the desired amount of ice cream mass  70 , wherein the described process “spreading on/scraping off” is repeated several times until an ice cream mass  70  of the desired consistency and quality (particularly in respect to a constant temperature) has been obtained. With the relatively large diameter of 30 cm of the processing container  10 , the number of spatulas and their speed of revolution of 142 rpm, a minimum dwell time of the liquid mixture  60  at the inner wall of the processing container of approximately 0.42 sec. results, which assures good freezing adhesion and freezing through. 
     Here it is already of importance that, because of the inclination of the spatulas by the second acute angle β, a movement component is created which assures that in the course of scraping the frozen portion  70 ′ from the inner wall of the processing container  10 , the latter falls back into the part pointing toward the removal opening  15  because of the effects of gravity, where the still existing rest of the liquid mixture  60  with the already frozen ice cream mass  70  contained therein is collected. 
     When this processing strip has ended, i.e. the actual production of ice cream, the closure element  15 A is opened and the speed of rotation of the spatula  21  . . . is increased, preferably to a value of approximately 288 rpm, which is intended to be expressed by the two-headed arrow P 3 . 
     In the course of this the further important function of the inclination of the spatula by the second acute angle β appears, namely the generation of a thrust component on the finished ice cream mass  70  (which is indicated by dotted lines in FIGS. 4 in contrast to the liquid mixture  60  indicated by shading). Because of the size of the removal opening  15  on the one hand, and the increased speed of rotation of the spatula on the other hand, the finished ice cream mass is ejected in a short time and practically without remnants out of the processing container  10  into the receiving container  50  (arrow P 5 ), which can then be pulled out of the support arms  41 ,  42  and inserted into a freezer chest, for example. 
     It becomes clear from the description of the structure and the mode of functioning of the device in accordance with the invention that with the clever design of the device an almost fully automatic operation from the introduction of the liquid mixture  60  to the removal of the container  50  with the finished ice cream is made possible, wherein the two angles α and β are of particular importance. Thus the device in accordance with the invention combines the processing advantage of the horizontally operating machine so far known with the excellent ice cream quality of the vertically operating machines and, with a suitable selection of the numbers of revolutions in accordance with the exemplary embodiment, a very gentle mechanical stress, which preserves the volume and the structure of the ice cream, is obtained in particular, which makes itself known in a long-lasting quality of the ice cream and which can also be put down to the fact that the work of the spatula in the course of ejecting the ice cream is aided by the effects of gravity because of the inclination of the processing container by the first acute angle, because the large-dimensioned removal opening  15  is located at the end of the lowest lying area of the processing container  10 . 
     The represented inclination of the processing container also makes possible further advantageous embodiments, for example the extremely simple cleaning, already mentioned at the outset, by spraying after the vat wall has been heated, wherein for example fresh water automatically sprayed behind the tool can run off again through the removal opening after the cleaning of the inner surface of the processing container  10 . Here, too, the joint-free design of the processing container  10  is very helpful, so that the manufacturing outlay required for welding is worth it, since the problem zones of the connection of various components with each other in the area of the processing container, described at the outset, are avoided. 
     The structural design of the processing area with few welded parts therefore makes an efficient production possible and assures that all sanitary requirements are met. 
     Further than that, the above described and already largely automated processing actions only require operating steps in a closely limited area, which can be selected in such a way that the operation of the device of the invention can take place in the immediately accessible area of an operator and without bending or stretching and without prolonged holding of loads, so that manipulation is very easy and health concerns of the operator are avoided.