Abstract:
Device to produce ice-cream wherein there is an outer container ( 11 ), a cover ( 26 ), an inner container ( 14 ), a mixing blade ( 20 ), and an evaporator coil ( 21 ) located in cooperation with the bottom ( 17 ) of the inner container ( 14 ), through at least a contact surface ( 27 ). The inner container ( 14 ) is axially mobile to assume at least an axial working position correlated to the position of the cover ( 26 ) when it is installed on the outer container ( 11 ), and is pressed elastically against the evaporator coil ( 21 ) by spring means ( 22 ) located under the evaporator coil ( 21 ).

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention concerns a device to produce ice-cream for ice-cream producing machines.  
           [0002]    The present invention is applied to ice-cream producing machines of a domestic or semi-professional type.  
         BACKGROUND OF THE INVENTION  
         [0003]    Machines of a domestic or semi-professional type are known, wherein the container where the ice-cream is formed cooperates with a mixing blade and with means to transfer the cold, or heat absorption means.  
           [0004]    The mixing blade takes motion from drive means associated with the cover.  
           [0005]    According to a variant, the blade takes motion from drive means located under or at the side of the container and connected to the mixing blade by a drive shaft which passes axially to the container with a cylindrical design. The drive means can be electric or manually driven.  
           [0006]    This type of machine, in relation to the chain of cold, has developed different design philosophies in relation to the cooperation of the heat absorption means with the container of the products which are transformed into ice-cream.  
           [0007]    A first design philosophy provides a fixed evaporator coil, that is, a coil wherein the temperature of the compressed gas goes down as it expands, which is cylindrical in shape; this coil surrounds the container, leaving an interspace between the coil and the container for the operations to insert and remove the container itself.  
           [0008]    This type of solution does not achieve an optimum heat exchange between the coil and the container, given the ring of air which, in fact, is greatly insulating.  
           [0009]    To improve the transfer of cold, it was then provided to fill, on each occasion, the ring of air with alcohol or other liquid which does not freeze at the normal working temperatures of the machine.  
           [0010]    Apart from the ever-present danger of fire, it is certainly not easy or simple to insert the container into a bath of alcohol. Moreover, there is always the danger of overflow.  
           [0011]    A second design philosophy has conceived of an elastic evaporator coil equipped with clamping means, as shown for example in U.S. Pat. No. 4,573,329 and in EP-A-129.706. By acting on the clamping means the evaporator coil opens or closes radially, so that it is possible to insert (or remove) the container by extracting it axially from the coil. When the container is inserted into the evaporator coil, the clamping means are activated and the evaporator coil contracts radially, surrounding, and closely connecting with, the peripheral cylindrical body of the container.  
           [0012]    This system guarantees an optimum heat absorption, but it has the drawbacks of the high cost of the evaporator coil and of the fact that it is easily damaged even by a careful user, and even more so by an inattentive user.  
           [0013]    Damage to the coil can also entail a dispersion into the environment of dangerous refrigeration gases.  
           [0014]    A system is also known, from JP-A-02-145153, which provides that the container is pressed elastically against the rotating mixing blade, by a coil located below.  
           [0015]    A proposal is also known, from U.S. Pat. No. 4,535,604, wherein it is provided that the container is held elastically pressed downwards by upper spring means, so that the lower flat part, which connects with the vertical cylindrical part, is in contact with a copper plate, of limited thickness and deformable.  
           [0016]    The copper plate is in contact with the coil of cylindrical tubes which involves both the flat part and also the part that connects to the vertical cylindrical part of the container.  
           [0017]    This solution is very interesting and advantageous, but it does include some disadvantages. First of all the heat exchange from the plate to the cooled tubes is limited, given the limited contact. Moreover, the presence of the spring located above creates problems of cleaning and safety for the user.  
           [0018]    Furthermore, the presence of circumferential blades, necessary to provide the container with the necessary pressure, located laterally or in the upper part of the container, creates not only difficulties in use, but also danger for the user. To this it must be added that, due to its very nature, the elastic mass located under the coil tends to memorize the deformation, and this memorization is accentuated over time. This automatically entails a loss of adherence.  
           [0019]    Furthermore, with the system disclosed by US &#39;604 it is possible to apply pressures of only a few kilograms on the pressure blades, which is not sufficient for a correct contact of heat transmission.  
           [0020]    Applicant therefore set himself the problem of finding an optimum solution to these problems and surprisingly found, and also studied, experimented and embodied the present invention.  
         SUMMARY OF THE INVENTION  
         [0021]    The present invention is set forth and characterized in the main claim, while the dependent claims describe other innovative characteristics of the invention.  
           [0022]    The purpose of the present invention is therefore to improve the performance in the cold chain in correspondence with the heat exchange between the evaporator coil and the container, at the same time achieving an optimum evaporator coil. The invention therefore tends to overcome known problems by achieving a very simple, low cost device, easy to use, simple to clean, without dangers for the user, which is advantageous even for a poorly qualified operator, simple and quick to maintain with little probability of damage.  
           [0023]    According to the invention, the system to absorb the heat between the container and the evaporator coil is achieved according to the general principles of US &#39;604 but with new and innovative concepts.  
           [0024]    According to the invention, the coil cooperates with spring means that, in a preferential embodiment, are arranged below a supporting base for the coil. The spring means are able to supply, in their entirety, from 200 to 600 kilograms of total thrust on containers having a diameter of about 130÷160 mm.  
           [0025]    The container, when the cover is on, assumes a working position wherein it is thrust elastically against the coil, thanks to the presence of the spring means.  
           [0026]    In an advantageous embodiment, the supporting base of the coil is made of plastic.  
           [0027]    According to a variant, the cold is transferred through a circular element, for example a toric ring, which affects the bottom of the container.  
           [0028]    According to another variant, the circular element also affects the peripheral edge of the container.  
           [0029]    The invention provides that the bottom of the container is substantially plane and made of the same material as the rest of the container.  
           [0030]    According to a variant, the bottom of the container has a layer of highly conductive material (copper, aluminum or suchlike) the function of which is not only to improve the heat exchange but also to make it uniform.  
           [0031]    According to another variant, at least the outer bottom of the container has a series of rings, which cooperate with mating rings present in the evaporator coil, in order to increase the exchange surface.  
           [0032]    In this case, one solution provides that the rings are obtained in an additional material applied on the bottom of the container.  
           [0033]    The rings can be V-shaped, wavy, or of any other type; only the fact that they serve to increase the exchange surface is relevant.  
           [0034]    According to another variant, the bottom of the container is arc-shaped, or like an inner or outer V, or according to another development tending to increase the surface of contact.  
           [0035]    According to another variant, the connecting edge between the bottom of the container and the vertical wall of the container cooperates with the evaporator coil.  
           [0036]    According to a variant, the coil is a tube with a thickness of between 0.2 and 0.6 mm. The supporting base has a smooth supporting surface for the coil; according to a variant, the supporting surface is shaped in the shape of the coil.  
           [0037]    According to a variant, once the coil is positioned, it is subjected to heading which generates at least a substantially plane contact surface on the upper part of the coil, thus improving the support. Advantageously, the heading generates two contact surfaces, one on the upper part and one on the lower part of the coil.  
           [0038]    According to the invention, one contact surface is obtained by reducing the height by a value of between 5% and 20%.  
           [0039]    According to one embodiment of the invention, between the container and the coil there is an intermediate plate, made of copper or aluminum, or iron, or plastic material; obviously, the terms copper, aluminum and iron also include the relative alloys.  
           [0040]    The thickness of the intermediate plate is between 0.1 and 0.6 mm, also depending on the material used to make it.  
           [0041]    According to the invention, the mixing blade not only performs the known function of mixing and introducing air into the ice-cream, but also the function of continuously raising the material, so that the cold transmitted to the bottom of the container and, from this, to the material in contact, is continuously carried upwards with a progressive uniformization of the temperature in the product. According to a variant, the mixing blade is shaped so as to cooperate in close proximity with the bottom of the ice-cream container.  
           [0042]    Applicant has also found that the size of the container, that is, the ratio between the usable inner diameter and the height of the level of product which can be obtained (that is, the ice-cream) improves the performance of the device according to the invention.  
           [0043]    According to a variant of the invention, this ratio is between 0.30 and 0.50, advantageously between 0.38 and 0.42.  
           [0044]    According to the invention, also considering that domestic or semi-professional ice-cream producing machines suffer from natural vibrations, the contact between the intermediate plate with the container and the evaporator coil must always be kept constant and this constant contact is maintained by a conductive paste or other suitable plastic material, located in cooperation with the coil.  
           [0045]    According to the invention, the contact between the container and the plate-coil system is maintained elastically due to the elastic thrust towards the container of the evaporator coil while the container remains fixed, in the working phase.  
           [0046]    According to the invention, the evaporator coil deforms elastically according to the thrust that it receives towards the container; this improves the heat yield.  
           [0047]    According to another variant, the coil is incorporated into a melted material, such as copper, aluminum or suchlike, or into said conductive paste, in order to improve the distribution and uniformity of the cold. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0048]    These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:  
         [0049]    [0049]FIG. 1 shows two practical embodiments of the invention in vertical section;  
         [0050]    [0050]FIGS. 2 a ,  2   b  and  2   c  show some possible conformations in section of the possible rings present between the mating contact surfaces, said rings being obtained in additional material;  
         [0051]    [0051]FIGS. 3 a ,  3   b  and  3   c  show some possible conformations of the bottom of the container defining mating contact surfaces. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0052]    In FIG. 1, which represents, in two different formulations, the part of the ice-cream producing machine to which the invention is applied, the device  10  can be seen; it is composed of a containing unit  11 , or outer container, having a housing compartment  12 , a supporting edge  13 , a supporting and contrasting edge  113  and a cover  26 .  
         [0053]    In the housing compartment  12 , and cooperating with the supporting edge  13  and with the cover  26 , there is an inner container  14 , hereafter simply container, having a positioning edge  15 , a cylindrical body  16 , a bottom  17  and a guide tube  18 . In this case, the bottom  17  is flat and connects with the cylindrical body  16 . The container  14  includes an inner compartment  114 .  
         [0054]    The drive shaft  19  moves and rotates inside the guide tube  18 , driven by drive means not shown here since they are already known, which gives motion to the mixing blade  20 .  
         [0055]    In the case shown, the bottom  17  is flat on the outside and cooperates with an evaporator coil  21  and with a base  25 , through mating contact surfaces, upper  27  and lower  127 . The upper contact surface  27  is pressed against the bottom  17  of the container  14  by a plurality of elastic means  22 , in this case helical springs, which rest on the bottom of the housing compartment  12 .  
         [0056]    The evaporator coil  21 , in this case, consists of a supporting and transmission plate or foil  23 , a coil element  24  and a base or support  25 , heat insulated towards the bottom.  
         [0057]    The elastic means  22  press on the base  25 .  
         [0058]    The coil element  24  is connected to the refrigeration system of the machine.  
         [0059]    In this case, between the plate  23  and the base  25 , according to the invention, material with a high coefficient of heat conduction can be inserted which fills all the spaces left free by the coil element  24 .  
         [0060]    In the case of the embodiment on the right in FIG. 1, the evaporator coil  21  operates only on the bottom  17 .  
         [0061]    In the case of the embodiment on the left in FIG. 1, the evaporator coil  21  also operates on the rounded edge  117  of the container  14 .  
         [0062]    In both cases, the plate or foil  23  is made of heat conductive material with a thickness of between 0.1 and 0.6 mm, advantageously 0.3 mm, so as not to impede the heat exchange and at the same time make it possible to clean the compartment  12 .  
         [0063]    The base or support  25  is advantageously made of plastic.  
         [0064]    The coil element  24  is made of copper pipe with a thickness of between 0.2 and 0.6 mm, advantageously 0.4 mm, in order to improve the heat exchange.  
         [0065]    The coil element  24 , after being conformed according to the geometric development of the exchange surface of the container  14 , can be subjected to a heading action able to create at least an upper contact surface  27 , and advantageously a lower contact surface  127  too.  
         [0066]    The contact surfaces  27 ,  127  include a plane segment which increases the heat exchange surface.  
         [0067]    The springs  22  can be metal or plastic material and can consist of a plurality of ring-shaped elements, or of a single ring-shaped element; they achieve an overall thrust of between 20 and 60 kg, advantageously  35 ÷45 kg.  
         [0068]    When the container  14  is in its seating and the cover  26  is in position, as a result of this thrust, together with the thickness of the tube, the coil element  24  deforms in an elastic field, guaranteeing an improved contact.  
         [0069]    The drive shaft  19  is connected at the upper part in a known manner and can be removed from the mixing blade  20 .  
         [0070]    The mixing blade  20  has a scraper fin  120  that cooperates with the part of the inner compartment  114  that is directly involved in the heat exchange, in order to prevent the formation of ice.  
         [0071]    The cover  26  is anchored to the outer container  11  by means of a rotation system which provides one or more approaching ramps in order to simplify and make closing less difficult for the operator.  
         [0072]    The approaching ramps determine the reciprocal axial position of the cover  26  with respect to the outer container  11 . The operator can therefore determine the reciprocal position of the outer container  11  and the cover  26 . This means that, in relation to the conformation of the ramps, that is, the circumferential position of the cover  26  with respect to the ramps, a greater or lesser compression is determined of the container  14  on the evaporator coil  21  and hence a greater or lesser adhesion between the reciprocal contact surfaces.  
         [0073]    According to the variant FIGS. 2 and 3, the coupling between the bottom  17  of the container  14  and the mating upper contact surface  27  of the coil  21  can assume various forms, such as rings having a geometric profile (wavy, V-shaped, etc.) (FIGS. 2 a  and  2   b ), arc-shaped (FIG. 3 a ), inner V-shaped (FIG. 3 b ) or outer V-shaped (FIG. 3 c ).  
         [0074]    In this case, to give an example, the container  14  has the following ratios if we assume the diameter D as 1; H, that is, the total height of the container is 0.55; h, that is, the usable height for the level of ice-cream is between 0.30 and 0.50, advantageously between 0.38 and 0.42, in this case 0.37.  
         [0075]    Variants of an artisan nature can be applied to the invention.  
         [0076]    It is clear however that modifications and/or additions of parts can be made to the device  10  as described heretofore, without departing from the field and scope of the present invention.