WO2001040720A1

WO2001040720A1 - Granular ice forming device

Info

Publication number: WO2001040720A1
Application number: PCT/IT2000/000491
Authority: WO
Inventors: Cesare Maroli
Original assignee: Brema Ice Makers S.P.A.
Priority date: 1999-12-03
Filing date: 2000-11-29
Publication date: 2001-06-07
Also published as: ITMI992530A0; IT1314255B1; ITMI992530A1; AU2394701A

Abstract

The invention relates to a device (10) for producing granular or flaked ice, consisting of a tubular body (20) in which the water to be frozen is circulated axially by a feeder screw (25) and around which the evaporator of a refrigerating assembly is arranged. The latter is advantageously composed of a helical rib (21) formed on the outside of the tubular body, and a sleeve (40) fitted around it. The device thus obtained has an excellent cooling capacity which allows to reduce its dimensions, without affecting the throughput of ice to be produced compared to conventional devices.

Description

GRANULARICE FORMING DEVICE

The invention relates to a device for forming granular or flaked ice.

As is known, this type of ice is commonly used for keeping fish, fruit and other foodstuffs in general at low temperature, when they are placed in crates or other containers for transportation thereof or when they are placed on stalls or tables in shops, restaurants and the like.

The production of granular ice for these uses is currently performed by devices similar to those which can be seen in Fig. 1 of the accompanying drawings. Basically, the device 1 houses internally the evaporator of a refrigerating machine, consisting of a coil 2 wound helically around a tubular body 3.

More specifically, both the body 3 and the coil 2 are made of metallic material (the coil usually of copper) and the latter is welded onto the former so as to ensure close contact between them which improves the thermal conductivity; a sleeve 4 coaxial with the tubular body is then applied around the assembly and defines together with the tubular body a cavity which is thermally insulated with insulating material 5.

During operation of the device 1, the bottom part of the body 3 is filled with water drawn from an external tank (not shown in the figure) and conveyed upwards by a feeder screw 6 located inside the body; at the same time, the refrigerating fluid circulates inside the coil 2 and, evaporating, cools the wall of the tubular body 3 around which the coil is wound.

The water, as it gradually rises, passes over the internal surface of the cooled tubular body and freezes: the continuous movement of the feeder screw 6 scrapes the ice thus formed and conveys it towards the top of the freezing device, from where it emerges in the desired granular form.

Such a state of the art is suitable for producing ice fulfilling the requirements of its intended uses; however, it has limitations which make the use thereof not particularly advantageous. First it may be noted that the welding (even using weld material such as tin or others) of the helical evaporator 2 onto the external surface of the body 3 is not a practical solution.

It is indeed not very easy to carrying out in view of the respective configurations of the elements to be joined together, i.e. a helically shaped pipe and a cylindrical surface; furthermore, it is also necessary to take suitable precautionary measures in order to avoid problems of differential heat expansion between the material of the tubular body and that of the coil (as mentioned the latter is usually made of copper, while the former may be made of steel). But above all it is the cooling capacity of the known freezing device which is to be regarded as not very satisfactory.

Indeed the heat exchange between the helical evaporator 2 and the wall of the body 3 where the ice is formed occurs partly by means of conduction along their welding joint, partly by means of convection of the air present between the spirals of the evaporator and which strikes both the latter and the external surface of the tubular body, partly by means of irradiation.

It can be easily understood that such a solution does not improve the transmission of the heat between the body 3 and the refrigerating fluid which circulates inside the evaporator, with the resulting consequence that it is necessary to provide fluid flows and/or heat exchange areas suitable for obtaining the required cooling.

In this connection it should also be pointed out that it is not possible to reduce excessively the pitch of the helical coil of the evaporator in order to increase the number of spirals and cool more efficiently the tubular body 3, since otherwise it would become problematic to perform welding thereof onto the body.

In view of the above explanation it may therefore be stated that in the known apparatus, the freezing device must be overdimensioned if a specific amount of ice is to be produced within a predefined time interval.

The object of the present invention is therefore that of overcoming the drawbacks of this state of the art.

That is, the invention aims at providing a device for the production of granular ice, having structural and operational features such as to overcome the abovementioned drawbacks and in particular to achieve an improved cooling capacity which would allow better performances.

This object is achieved by a device whose characterising features are described in the claims which follow.

These characterising features and the advantages of the invention will emerge more clearly from the description provided hereinbelow, of a preferred and non-exclusive embodiment thereof illustrated in the accompanying drawings wherein:

- Fig. 1 shows, as already mentioned, a freezing device of known type;

- Fig. 2 shows an example of an apparatus according to the invention;

- Fig. 3 shows the freezing device of the apparatus of Fig. 2; - Fig. 4 shows a longitudinal section through the freezing device.

With reference to these drawings, reference numeral 10 indicates a device for the production of granular ice according to the invention.

This device comprises a tubular body 20 shown in detail in Fig. 4, which has a helical rib extending over a central band thereof; the width of this band lies between a top opening 22 for discharging the granular ice from the body 20 and a bottom hole 23 for entry of the water supplied via a channel 24. The latter is connected upstream to a tank filled with water (not shown in the drawings).

The abovementioned rib 21 may be formed by means of milling and/or turning of the tubular body 20 or using any other suitable machining method. The body 20 houses internally a feeder screw 25 supported at its ends by two bearings 26 and 27, the second of which is doubled in the sense that it comprises a thrust bearing and a radial bearing; in particular, with reference to the figures it can be seen how the bottom end of the feeder screw terminates with a shank 28 which projects beyond the tubular body 20, wherein a ceramic and graphite sealing ring 29 is applied for protecting the bearing 27 from the water present in the bottom part of the body 20.

The sealing ring 29 is housed in a bush 30 and is kept in position by a spring 31 acting thereon and on the bottom of the feeder screw 25. The top end of the tubular body 20 is closed by a lid 32, while on the opposite end there is mounted, by means of a flanged joint 33, a casing 35; the latter serves as a housing for the bearing 27 of the feeder screw 25 and as a support for fixing the operation system of the latter (not shown in the Figures).

On the tubular body 20 there is also has fitted a cylindrical sleeve 40, which covers the band where the helical rib 21 is formed.

As can be seen from Figure 3, the sleeve 40 delimits together with the external surface of the tubular body 20, a cylindrical cavity 41 which has a radial thickness (i.e. measured over a radius relative to the axis of the freezing device 10 indicated by the vertical dot-dash line in Figures 2 and 3) close to that of the rib 21 and is sealed at the ends: the rib 21 therefore defines, within the cavity 41, a helical path along which the refrigerating fluid supplied from the outside by a pipe 43 engaging into the bottom part of the cavity, is circulated. The refrigerating fluid is then discharged from the top of the latter, via an outlet pipe 44.

In a preferred embodiment, a sensor 45 for detecting the temperature inside the cavity 41 is arranged along the abovementioned helical path of the refrigerating fluid; finally it must be mentioned that the device 10 is also thermally insulated with an insulation outside the sleeve 40 (not shown in the drawings) similar to that of the known art.

The production of ice with the device 10 described above occurs substantially in the manner already explained.

The water coming from the channel 24 and supplied into the bottom part of the tubular body 20 via the hole 23, is raised by the feeder screw 25 following rotation of the latter and freezes upon contact with the internal wall of the tubular body, cooled by the refrigerating fluid which circulates inside the cavity 41. The flaked ice then comes out from the opening 22 located at the top of the tubular body 20.

As can be seen, therefore, as to the formation of ice, the device according to the present invention generally applies the same operating principle as the prioritat considered above; on the contrary, however, the manner with which cooling of the tubular body occurs inside it is completely different.

Indeed, in this case the refrigerating fluid which circulates along the helical path defined by the rib 21, is in contact with the external surface of the tubular body; consequently it is plainly evident that the heat exchange between them occurs directly, namely by means of convection between the fluid and the aforementioned surface.

On this regard it should be noted that since the fluid is subject to a phase transition, as a result of its evaporation following the heat absorbed by the wall of the tubular body, in this case the convection heat exchange coefficient is (as it is well known) fairly high, thereby contributing to maximise the capacity of the device according to the invention from this point of view.

Such a result is further enhanced by the fact that the entire band of the tubular body 20 lying between the water inlet hole 23 and the ice outlet opening 22, is fully in contact with the refrigerating fluid. In other words, the spirals of the helical gas path defined by the rib 21 are attached to each other so as not to leave exposed, i.e. not licked by the refrigerating fluid, any zone of the surface of the tubular body.

In order to appreciate this fact, it is sufficient to make a comparison with the known device according to Fig. 1 in which the spirals of the coil 2 are spaced from each other so that the evaporator, in fact, does not cover entirely the tubular body 3; as mentioned, this occurs because it is required to leave in any case a certain amount of free space between the spirals, in order to allow their welding on the body around which they are wound.

It should also not be overlooked that the rib 21 in this case is a kind of cooling fin (such as those arranged, for example, on the outside of the engines of motorcycles) which favourably provides for the overall heat exchange.

It is also important to mention how the configuration of the freezing device 10 according to the invention is fairly compact and simple to manufacture. This is due to the fact that, owing to the improved capacity for heat exchange, it is now possible to reduce, without modifying the performances, both the length of the tubular body and the flow of fluid circulating in the evaporator.

Of course variations of the invention with respect to what has been described hitherto are possible. For example, it may be appreciated that the arrangement of the water inlet hole 23 and the ice outlet opening 22 may be different from that shown in the drawings.

It is further obvious that the invention does not exclude the circulation of the refrigerating fluid in counter-current with respect to the water (and the ice being formed) inside the tubular body.

Also as regards the rib 21, other embodiments different from that considered herein are possible.

For example, an alternative embodiment could be obtained by applying the rib on the outside of the tubular body, instead of forming it directly thereon by machining it with a machine-tool; this could be the case when the rib is made of a material different from that of the tubular body, for example teflon, rubber or the like, so as to ensure a better seal with the external sleeve 40.

It is also possible that the tubular body be made of a non-metallic material, by moulding or other suitable processing operation. Finally, it should also be pointed out that the same effects described above could be obtained by means of a freezing device in which the helical rib is formed (or applied) inside the sleeve, while the external surface of the tubular body is smooth, namely by mutually inverting the surface characteristics of these two elements. All these and other variants are in any case to be regarded as included within the scope of the following claims.

Claims

1. Granular ice forming device, comprising a tubular body (20), a feeder screw (25) rotating inside the body for axially feeding water supplied inside it and expelling granular ice through an outlet opening (22), an evaporator (20, 40, 41) of a refrigerating assembly associated with the tubular body for cooling thereof, characterized in that the evaporator comprises a helical rib (21) projecting on the external surface of said body, a sleeve coaxially coupled the body so as to delimit therewith a tubular cavity (41) inside which the rib defines a helical path for the refrigerating fluid circulating in the evaporator.

2. Device according to Claim 1, wherein the rib (21) is formed on the external surface of the tubular body (20).

3. Device according to Claim 2, wherein the rib (21) is formed by means of removal of material from the tubular body (20), by means of turning, milling or other suitable machining operation.

4. Device according to Claim 1, wherein the rib (21) substantially consists of a seal made from teflon, rubber or the like, which is applied onto the external surface of the tubular body (20).

5. Device according to any one of the preceding claims, wherein an end of the tubular body (20) has, fixed to it, a casing (35) which houses a bearing (27) for supporting a projecting shank (28) of the feeder screw (25) and a ceramic and/or graphite seal for ensuring sealing from the water present in the tubular body.

6. Granular ice forming device, comprising a tubular body (20), a feeder screw (25) rotating within the body for axially feeding water supplied inside it and expelling granular ice through an outlet opening (22), an evaporator

(21, 40, 41) of a refrigerating assembly associated with the tubular body for cooling thereof, characterized in that the evaporator comprises a sleeve (40) coupled coaxially to the tubular body so as to delimit therewith a tubular cavity (41), a helical rib (21) which projects from the internal surface of the sleeve and defines inside the cavity a helical path for the refrigerating fluid circulating through the evaporator.