FAN BLADE AND CORRESPONDING FAN

Abstract

 In order to overcome the limitations and problems that earlier apparatus have experienced, a fan blade (12) is proposed, said fan blade (12) comprising an interior space (16) and a plurality of holes (26) in fluid communication with said interior space (16) and from which a high pressure cryogenic gas (34) is ejected for cleaning a surface (14) of the fan blade (12).
A corresponding self-cleaning fan (10) is also proposed.

Description

Technical field of the present invention

[0001] The present invention relates to a fan blade as well as to a fan, in particular used in a freezer, for example in a tunnel freezer, such as in a cryogenic tunnel freezer, for at least one product, in particular for at least one food product.

Technological background of the present invention

[0002] Axial flow fans are used in cryogenic tunnel freezers. When hot steamy products, such as for example food products, are frozen in cryogenic processes, ice and snow accumulate on the surfaces of the axial flow fan blades. This snow and ice accumulation creates two main issues:

First, performance of the fan blade diminishes because the blade cannot move gas as efficiently, resulting in lower volumetric and velocity flow from the fan. This equates to lower overall heat transfer coefficients in the freezing process and decreased production rates.

[0003] Second, the fan becomes imbalanced, causing vibration which affects the bearings in the motor driving the fans. Bearings fail prematurely and motors must be replaced more frequently. The freezer becomes susceptible to downtime to do repairs, leading to greater inefficiencies in the freezing process.

Disclosure of the present invention: object, solution, advantages

[0004] Starting from the disadvantages and shortcomings as described above as well as taking the prior art as discussed into account, an object of the present invention is to overcome the limitations and problems that earlier apparatus have experienced.

[0005] This object is accomplished by an apparatus comprising the features of claim 1 as well as by an apparatus comprising the features of claim 8. Advantageous embodiments, expedient improvements and other optional features of the present invention are set forth herein and disclosed in the respective dependent claims.

[0006] There is basically provided a self de-icing fan blade, in particular for hot products, and more specifically there is provided herein a fan blade which includes an interior space, in particular an annular space, and a plurality of holes in fluid communication with said interior space and from which a high pressure cryogenic gas is ejected for cleaning a surface of the fan blade.

[0007] According to an advantageous embodiment of the present invention, the rotary coupling may provide a passageway therethrough for the cryogenic gas to be fed or directed to the interior space.

[0008] In an expedient embodiment of the present invention, a high pressure rotary seal may be disposed in the rotary coupling, said seal allowing a hub of the rotary coupling to rotate and/or a gas feed pipe to remain stationary.

[0009] There is further provided herein a self-cleaning fan which includes a blade having an interior space and a plurality of holes along the blade in fluid communication with the interior space; a rotary coupling, mounted to and operatively associated with the blade, the rotary coupling having an interior portion in fluid communication with the interior space and a source of cryogenic gas; and a valve interposed between the interior portion of the rotary coupling and the cryogenic gas source for selectively releasing a high pressure flow of the cryogenic gas into the interior portion and through the interior space for discharge from the plurality of holes onto a surface of the blade without having to cease rotation of the blade.

[0010] According to a favoured embodiment of the present invention, the fan may be rotatably mounted to a shaft which may be operationally associated with a motor disposed at an exterior of a freezer so as not to transfer heat from the motor to an interior of the freezer.

[0011] The freezer may be a cryogenic tunnel freezer, in particular for chilling and/or freezing food products being transported by means of a conveyor belt through the interior of the freezer.

[0012] In a preferred embodiment of the present invention, a pipe may extend along an exterior of the freezer and may comprise a proximate end in fluid communication with the interior portion such that the cryogenic gas can be introduced through the rotary coupling and into the interior space. A distal end of the pipe may be in fluid communication with a buffer tank for the cryogenic gas, said buffer tank being intermittently fed with the cryogenic gas from the source and/or operating as an accumulator which may be pressurized to ultimately provide the cryogenic gas to the interior space for cleaning the surface at select time periods or intervals.

[0013] The present embodiments enable the fans to shed snow and ice during operation, and overcome the problematic issues outlined above with respect to known axial flow fans.

[0014] In general, the present embodiments include fan blades constructed with an interior void for pressurization with high pressure nitrogen gas or high pressure carbon dioxide gas. The surface of the blade includes a plurality of small holes which restrict gas flow and create high velocity jets of nitrogen gas when the fan blade void is pressurized.

[0015] Additionally, a rotary coupling is installed for operation with the fan. An electrically powered fan motor is mounted to the roof of a food freezer and connected by a shaft to the rotary coupling. The fan motor rotates the fan blade a speeds of from 1750 revolutions per minute (rpm) to 3500 rpm.

[0016] The rotary coupling includes an interior annular space or chamber portion which is provided or fed with high pressure nitrogen gas through a high flow valve from a high pressure buffer storage tank. The buffer storage tank can be filled with the high pressure nitrogen gas over a select duration of time.

[0017] That is, the storage tank does not require a fast recharge (refill) time period and therefore, the flow rate of the nitrogen gas into said tank can be done over a period of minutes.

[0018] For example, it may take twenty minutes to refill the storage tank, but the cycle of using the gas in the present embodiments may, for example, be only three seconds.

[0019] When a de-icing cycle for the fan blade is needed in order to clear same of accumulated snow and ice, the high flow valve is opened to release the high pressure nitrogen gas to the annular space of the rotating fan blade, which gas is then discharged through the plurality of holes in the blade.

[0020] The tight spacing and close proximity of the holes with each other on the blade enables the high pressure-high velocity nitrogen gas to contact any snow and ice on the blade surface for removal therefrom.

Brief description of the drawings

[0021] For a more complete understanding of the present embodiment disclosures and as already discussed above, there are several options to embody as well as to improve the teaching of the present invention in an advantageous manner. To this aim, reference may be made to the claims dependent on claim 1 as well as on claim 8; further improvements, features and advantages of the present invention are explained below in more detail with reference to the particular and preferred embodiments by way of non-limiting example and to the appended drawing figures taken in conjunction with the following description of exemplary embodiments, of which:

FIG. 1

shows a side view of a fan embodiment according to the present invention, said fan embodiment working according to the method of the present invention;

FIG. 2

shows a cross-sectional view of a fan blade embodiment according to the present invention, said fan blade embodiment being disposed for operation in the fan embodiment of FIG. 1; and

FIG. 3

shows a partial cross-sectional view of a tunnel freezer embodiment according to the present invention in which the fan embodiment of FIG. 1 is disposed for operation.

[0022] The accompanying drawings are included to provide a further understanding of the apparatus and method(s) provided herein and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the apparatus and method(s) provided herein and, together with the description, serve to explain the principles described herein but are not intended to limit the specification or any of the claims. In the accompanying drawings, like equipment is labelled with the same reference numerals throughout the description of FIG. 1 to FIG. 3.

Detailed description of the drawings;

best way of embodying the present invention

[0023] Before explaining the present inventive embodiments in detail, it is to be understood that the embodiments are not limited in its respective application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the present invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

[0024] In the following description, terms such a horizontal, upright, vertical, above, below, beneath and the like, are used solely for the purpose of clarity illustrating the present invention and should not be taken as words of limitation. The drawings are for the purpose of illustrating the present invention and are not intended to be to scale.

[0025] Referring now to FIG. 1 to FIG. 3, a self de-icing fan blade of the present embodiments is shown generally at 10 and includes a body portion 12 having an exterior surface 14 and defining an internal chamber 16, annular space or void within the blade. The chamber 16 can assume the proportions of and also be referred to as an annular space 16.

[0026] As shown in FIG. 1, the fan 10 referred to may have a plurality of blades 12, each one of which is joined to a rotary coupling 18, or be considered as a single blade to which the rotary coupling 18 is interposed as a central, unifying member. With either construction, the rotary coupling 18 transmits a rotating force to the fan blade 12 for generating an axial gas flow 19 to products 60, such as for example food products, to be chilled and/or frozen as described below.

[0027] The rotary coupling 18 provides a passageway 20 therethrough for high pressure cryogenic gas 34 to be fed or directed to the chamber 16 of the blade 12 along the blades' axis of rotation while same is rotating or spinning, as indicated with arrow 22. A high pressure rotary seal disposed in the rotary coupling 18 allows a hub of the coupling 18 to rotate and the gas feed pipe 24 to remain stationary.

[0028] The fan blade 12 includes a plurality of holes 26 and for certain applications a myriad of the holes 26, in close proximity to each other along the surface 14 of the fan blade 12, each one of the holes 26 in fluid communication with the annular space 16 of the fan blade 12 for a purpose to be described hereinafter.

[0029] The rotary coupling 18 has an internal portion 28 in fluid communication with the annular space 16 of the fan blade 12 as shown in FIG. 1, such that the cryogenic gas, such as for example gaseous nitrogen or gaseous carbon dioxide can be directed through a passageway 30 of a shaft 32 into the rotary coupling 18 and dispersed to the annular space 16 of the fan blade 12.

[0030] As described hereinafter, pressurized gas 34 will be moved from the annular space 16 of the fan blade 12 through the plurality of holes 26 for the self-cleaning of the external surface 14 of the fan blade 12.

[0031] Referring to FIG. 3, the fan 10 embodiment may be mounted for operation in an internal space 36 or chamber of a freezer 38, such as for example a tunnel freezer for food products 60. As shown, the fan 10 is rotatably mounted to the shaft 32 which in turn is operationally associated with a motor 40 disposed at an exterior of the freezer 38 so as not to transfer heat from the motor 40 to the internal chamber 36 of the freezer 38.

[0032] A pipe 39 or fluid conduit extends along an exterior of the freezer 38 and has one or a proximate end 46 (cf. FIG. 2) of the pipe 39 in fluid communication with the internal portion 28 of the rotary coupling 18 such that cryogenic gas 34 under pressure can be introduced through the rotary coupling 18 and into the annular space 16 of the fan blades 12.

[0033] Another or a distal end 48 of the pipe 39 is in fluid communication with a buffer storage tank 50 for the cryogenic gas 34, which tank 50 can be intermittently fed with the cryogenic gas 34 such as nitrogen gas or carbon dioxide gas from a remote source (not shown).

[0034] In effect, the buffer tank 50 operates as an accumulator which is pressurized to ultimately provide the cryogen gas 34 to the annular space 16 of the fan blade 12 for cleaning the external surface 14 thereof at select time periods or intervals. A high flow valve 52 is interposed in the pipe 39 interconnecting the buffer tank 50 and the rotary coupling 18.

[0035] During operation, when a detrimental amount of snow and/or of ice has accumulated on the exterior surface 14 of the self-cleaning fan 10, the buffer tank 50 is charged with the cryogen gas 34 to a predetermined pressure, at which point the high flow valve 52 is opened causing said pressurized gas 34 to be delivered through the pipe 39, through the rotary coupling 18 and into the annular space 16 of the fan blade 12 for expulsion through the plurality of holes 26 to dislodge and clean the accumulated snow and/or ice from the surface 14 of the fan blade(s) 12. The expulsion of the gas 34 from the holes 26 is in the form of jet sprays 56.

[0036] A conveyor belt 58 can be used to transport the products 60 through the space 36 of the freezer 38 so that the products 60 are subjected to the chilling atmosphere in the space 36 and contacted by the chilled axial gas flow 19.

[0037] The frequency of the de-icing can be adjusted based on the severity of the ice and snow accumulation on the fan blades 12.

[0038] The embodiments provided herein may also include said cryogenic gas being selected from the group consisting of nitrogen gas and CO₂ gas.

[0039] It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the present invention. All such variations and modifications are intended to be included within the scope of the present invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the present invention may be combined to provide the desired result.

List of reference signs

[0040] 

10

fan, in particular self-cleaning fan

12

blade, in particular fan blade or body portion of fan 10

14

surface, in particular exterior surface, of blade 12

16

internal chamber or interior space, in particular annular space or void

18

rotary coupling

19

axial gas flow, in particular chilled axial gas flow

20

passageway through rotary coupling 18

22

direction of rotating or spinning

24

gas feed pipe

26

hole, in particular small hole, in blade 12, in particular over entire surface 14

28

interior portion or internal portion of rotary coupling 18

30

passageway of shaft 32

32

shaft

34

gas, in particular high pressure cryogenic gas, for example nitrogen gas or carbon dioxide gas, into blade 12

36

interior, in particular internal space or internal chamber, of freezer 38

38

freezer, in particular tunnel freezer, for example cryogenic tunnel freezer

39

pipe or fluid conduit

40

motor

46

first or proximate end of pipe or fluid conduit 39, in particular serving as inlet for gas 34

48

second or distal end of pipe or fluid conduit 39, in particular serving as outlet for gas 34

50

buffer tank, in particular buffer storage tank, for cryogenic gas 34

52

valve, in particular high flow valve

56

high pressure gas discharge, in particular jet spray

58

conveyor belt

60

product, in particular food product

Claims

1. A fan blade (12), comprising an interior space (16) and a plurality of holes (26) in fluid communication with said interior space (16) and from which a high pressure cryogenic gas (34) is ejected for cleaning a surface (14) of the fan blade (12).

2. The blade according to claim 1, wherein the interior space (16) is an annular space.

3. The blade according to claim 1 or 2, wherein the rotary coupling (18) provides a passageway (20) therethrough for the cryogenic gas (34) to be fed or directed to the interior space (16).

4. The blade according to at least one of claims 1 to 3, wherein a high pressure rotary seal is disposed in the rotary coupling (18), said seal allowing a hub of the rotary coupling (18) to rotate and/or a gas feed pipe (24) to remain stationary.

5. The blade according to at least one of claims 1 to 4, wherein the cryogenic gas (34) is selected from the group consisting of nitrogen gas and carbon dioxide gas.

6. The blade according to at least one of claims 1 to 5, wherein the fan blade (12) is mounted for operation at an interior (36) of a freezer (38).

7. The blade according to claim 6, wherein the freezer (38) is a cryogenic tunnel freezer.

8. A self-cleaning fan (10), comprising:

- a blade (12) having an interior space (16) and a plurality of holes (26) along the blade (12) in fluid communication with the interior space (16);

- a rotary coupling (18) mounted to and operatively associated with the blade (12), the rotary coupling (18) having an interior portion (28) in fluid communication with the interior space (16) and a source of cryogenic gas (34); and

- a valve (52) interposed between the interior portion (28) and the source of the cryogenic gas (34) for selectively releasing a high pressure flow of the cryogenic gas (34) into the interior portion (28) and through the interior space (16) for discharge from the plurality of holes (26) onto a surface (14) of the blade (12) without having to cease rotation of the blade (12).

9. The fan according to claim 8, wherein the blade (12) is embodied according to at least one of claims 1 to 7.

10. The fan according to claim 8 or 9, wherein the fan (10) is rotatably mounted to a shaft (32) which is operationally associated with a motor (40) disposed at an exterior of a freezer (38) so as not to transfer heat from the motor (40) to an interior (36) of the freezer (38).

11. The fan according to claim 10, wherein a pipe (39) extends along an exterior of the freezer (38) and comprises a proximate end (46) in fluid communication with the interior portion (28) such that the cryogenic gas (34) can be introduced through the rotary coupling (18) and into the interior space (16).

12. The fan according to claim 11, wherein a distal end (48) of the pipe (39) is in fluid communication with a buffer tank (50) for the cryogenic gas (34), said buffer tank (50) being intermittently fed with the cryogenic gas (34) from the source.

13. The fan according to claim 12, wherein the buffer tank (50) operates as an accumulator which is pressurized to ultimately provide the cryogenic gas (34) to the interior space (16) for cleaning the surface (14) at select time periods or intervals.

14. The fan according to at least one of claims 8 to 13, further comprising a conveyor belt (58) for transporting at least one product (60) through the interior (36) of the freezer (38).

15. The fan according to claim 14, wherein the at least one product (60) is at least one food product.

Drawing