US20110126818A1

US20110126818A1 - Radial jet air impingement nozzle, oven and method

Info

Publication number: US20110126818A1
Application number: US12/784,864
Authority: US
Inventors: Martin Behle; Douglas S. Jones
Original assignee: Merrychef Ltd
Current assignee: Welbilt UK Ltd
Priority date: 2009-05-22
Filing date: 2010-05-21
Publication date: 2011-06-02
Also published as: EP2433057A4; WO2010135693A1; EP2433057A1

Abstract

An oven that generates impingement air with a jet nozzle that includes a nozzle insert that provides a slot-shaped orifice through which the air flows toward a product to be heated or cooled. In particular, an oven for cooking a food product is disclosed in which a plurality of the jet nozzles produces an overall turbulence and a homogeneous heat transfer at a surface of the food product.

Description

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser. No. 61/180,575, filed on May 22, 2009, the entire contents of which are incorporated herein.

FIELD OF THE INVENTION

This disclosure relates to new and improved air impingement nozzles, methods and ovens that use the nozzles for heating or cooling a product within the air streams coming out of the air impingement nozzles. For example, the improved impingement nozzles can be used in an oven for cooking food products.

BACKGROUND OF THE DISCLOSURE

Jet nozzles are used to provide impingement air to heat or cool a product in a variety of ovens, including countertop ovens, conveyor ovens, and the like. Several known jet nozzles are shown in U.S. Pat. No. 6,817,283, which discloses an oven for cooking food products. In some applications, the jet nozzles are shaped and spaced to provide non-overlapping columns of hot impingement air that impinge directly on the surface of the food product. A disadvantage of these nozzles is that the columns of hot impingement air develop hot spots that result in a pattern of overcooked and undercooked areas of the food product. In other applications, the jet nozzles are shaped and spaced to provide a plume or blanket of hot air at the surface of the food product.
There is a need for an improved jet nozzle.
There is also a need for a method and an oven with the improved jet nozzles.

SUMMARY OF THE DISCLOSURE

The present disclosure describes a jet nozzle that provides hot air acceleration and a nozzle insert or member in the flow path beneath the jet nozzle that transforms the air flow to create a relatively thin thermal boundary layer of hot air at the surface of the food, utensil or any other material placed within the air stream that is characterized by an overall flow pattern at the surface of the food product that enhances the heat transfer to the product. In a preferred embodiment, the member has a cone like or goblet like shape that causes the airflow to form a relatively thin bell-shaped flow ring after separating from the nozzle insert, which leads to a more homogeneous and high heat distribution cooking of food products.
One embodiment of an oven of the present disclosure comprises an oven chamber and a blower that is disposed to circulate air through the oven chamber. An air impingement plate is disposed in the circulating air and is located to provide impingement air toward a product in the oven chamber. At least one jet nozzle is disposed in the impingement plate. A nozzle insert is disposed in relation to the jet nozzle to form about the nozzle insert a slot-shaped orifice through which the impingement air flows.
In another embodiment of the oven of the present disclosure, a shape of the slot-shaped orifice is selected from the group consisting of: curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.
In another embodiment of the oven of the present disclosure, a shape of the nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.
In another embodiment of the oven of the present disclosure, the slot-shaped orifice has a thickness that produces an overall flow pattern at the surface of the product that enhances heat transfer to the product and a homogeneous heat transfer at a surface of the product.
In another embodiment of the oven of the present disclosure, the nozzle insert is selected from the group consisting of: solid and hollow.
In another embodiment of the oven of the present disclosure, a shape of the jet nozzle is selected from the group consisting of: a match with a shape of the nozzle insert and a non-match of a shape of the nozzle insert.
In another embodiment of the oven of the present disclosure, the jet nozzle is one of a plurality of jet nozzles that each have an associated nozzle insert in relation to the jet nozzle to form about the nozzle insert a slot-shaped orifice through which the impingement air flows. The plurality of jet nozzles collectively provide a homogeneous and high heat transfer distribution at the product.
In another embodiment of the oven of the present disclosure, a temperature of the air is controlled by a unit selected from the group consisting of: heating and cooling.
In another embodiment of the oven of the present disclosure, a fastener fastens the nozzle insert to the impingement plate to vary an axial position of the nozzle insert relative to the impingement plate.
In another embodiment of the oven of the present disclosure, a heater is disposed to heat the circulating air, and wherein the product is a food product.
In one embodiment of the method of the present disclosure, the oven is operated by steps comprising:
circulating air in an oven chamber;
providing an impingement plate in the circulating air to provide impingement air toward a product in the oven chamber; and
shaping the impingement air with a slot-shaped orifice through which the impingement air flows.
In another embodiment of the method of the present disclosure, a shape of the slot-shaped orifice is selected from the group consisting of: curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.
In another embodiment of the method of the present disclosure, a temperature of the air is controlled by a unit selected from the group consisting of: heating and cooling.
In another embodiment of the method of the present disclosure, a heater is disposed to heat the circulating air, and the product is a food product.
In another embodiment of the method of the present disclosure, at least one jet nozzle is disposed in the impingement plate. A nozzle insert is disposed in relation to the jet nozzle to form about the nozzle insert the slot-shaped orifice through which the impingement air flows.
In another embodiment of the method of the present disclosure, a shape of the nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.
In another embodiment of the method of the present disclosure, the slot-shaped orifice has a thickness that produces an overall flow pattern at the surface of the product that enhances heat transfer to the product and a homogeneous heat transfer at a surface of the product.
In another embodiment of the method of the present disclosure, the insert is selected from the group consisting of: solid and hollow.
In another embodiment of the method of the present disclosure, a shape of the jet nozzle is selected from the group consisting of: a match with a shape of the nozzle insert and a non-match of a shape of the nozzle insert.
In another embodiment of the method of the present disclosure, the jet nozzle is one of a plurality of jet nozzles that each have an associated nozzle insert in relation to the jet nozzle to form about the nozzle insert a slot-shaped orifice through which the impingement air flows. The plurality of jet nozzles collectively provides a homogeneous and high heat transfer distribution at the product.
In another embodiment of the method of the present disclosure, a fastener fastens the nozzle insert to the impingement plate to vary an axial position of the nozzle insert relative to the impingement plate.
In one embodiment of the jet nozzle of the present disclosure, a jet nozzle is disposed in an air impingement plate and at least one nozzle insert is disposed in relation to the jet nozzle to form about the nozzle insert a slot-shaped orifice through which impingement air flows.
In another embodiment of the jet nozzle of the present disclosure, a shape of the slot-shaped orifice is selected from the group consisting of:
curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.
In another embodiment of the jet nozzle of the present disclosure, a shape of the nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.
In another embodiment of the jet nozzle of the present disclosure, a shape of the jet nozzle is selected from the group consisting of: a match with a shape of the nozzle insert and a non-match of a shape of the nozzle insert.
In another embodiment of the jet nozzle of the present disclosure, the nozzle insert is selected from the group consisting of: solid and hollow.
In another embodiment of the jet nozzle of the present disclosure, a fastener fastens the nozzle insert to the impingement plate to vary an axial position of the nozzle insert relative to the impingement plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and:

FIG. 1 is a perspective view of the oven of the present disclosure;

FIG. 2 is a cross-sectional view along line 2 of the oven of FIG. 1;

FIG. 3 is a block diagram of the electrical control of the oven of FIG. 1;

FIG. 4 is a perspective view of the jet plate of the oven of FIG. 1;

FIG. 5 is a profile view of a nozzle with nozzle insert of the jet plate of FIG. 3;

FIG. 6 is a perspective view of the nozzle of FIG. 5 attached to a section of the jet plate of FIG. 4; and

FIGS. 7-12 are perspective views of alternate embodiments of the nozzle insert for the jet plate of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

It is contemplated that the jet nozzles of the present disclosure can be used in any type of oven that uses impingement air. By way of example and completeness of description, the nozzles are described herein for use with a countertop oven.
Referring to FIGS. 1 and 2, an oven 30 of the present disclosure comprises a pair of side walls 32 and 34, a back wall 36, a top wall 38, a bottom wall 40 and a front wall 42. Front wall 42 comprises a door 44 and a control panel 50 (shown in FIG. 3), which, for example, may be located above, below or beside door 44. A handle (not shown) is disposed on door 42 for opening the door in a pull down manner or a side rotatable manner.
Oven 30 comprises an oven chamber 70 defined by side walls 32 and 34, back wall 36, bottom wall 40 and a jet plate 72. Jet plate 72 is disposed below top wall 38. Oven 30 further comprises a fan box 74 defined by side walls 32 and 34, back wall 36, top wall 38 and a wall 76. A fan 80 is disposed in fan box 74 and a heater 52 (shown in FIG. 3) is disposed on the high pressure side of fan 80. In alternate embodiments, heater 52 may be located on the suction side of fan 80. For example, heater 52 may be located in front of an opening 86 in back wall 36 that is at least partly in alignment with fan 80. Fan 80 may be any fan suitable for circulating air in an oven. A fan motor 82 is axially connected to drive fan 80. Fan motor 82 may be a single speed or a variable speed motor that rotates in a single direction or in both directions. In one embodiment, fan motor 82 is a three phase cage induction motor suitable for inverter drive, preferably L7FWDS-638 manufactured by Hanning. Heater 52 may be any heater (gas, induction, microwave, electric and the like) suitable for heating circulating air in a convection and/or impingement air oven. Preferably, heater 52 is an electrical heater having one or more heating elements disposed in a peripheral location of the blades of fan 80.
An oven rack 84 is supported within oven chamber 70 by any suitable means that allows for proper location in oven chamber 70 (e.g., mounted to side walls 32 and 34, bottom wall 40, back wall 36, front wall 42, door 44 and the like). Oven rack 84 may be a standard food rack, i.e., available off-shelf. In an alternate embodiment a plurality of oven racks 84 may be disposed in oven chamber 70.
Referring to FIGS. 1, 2 and 4, back wall 36 comprises a plurality of openings to provide a path for air to circulate between oven chamber 70 and fan box 74. Opening 86 is located above the bottom of back wall 36. A grease filter (not shown) may be mounted to back wall 36 to cover opening 86, which is preferably at least partially in registration with fan 80. An opening 88 is located at or near the top of back wall 36.
A catalyst structure (not shown) may be disposed in fan box 74 between fan 80 and back wall 36. For example, the catalyst may be disposed adjacent back wall 36 in at least partial registration with opening 88 of back wall 36 and fan 80. Opening 86 may be configured to block microwave energy penetration in microwave embodiments. In an alternate embodiment, the catalyst structure may be located in front of opening 86.
Referring to FIG. 3, a controller 54 is connected in circuit with control panel 50, fan motor 82, heater 52 and a temperature sensor 56. Controller 54 is operative in response to operator commands entered via control panel 50 to control fan motor 82 to drive fan 80 to circulate air from the high pressure side of fan 80 in a path that includes fan box 74, opening 88, jet plate 72 oven chamber 70 and opening 86 to the low pressure side of fan 80 as shown by the arrows in FIG. 2. Temperature sensor 56 may be disposed in oven chamber 70 to sense the oven chamber temperature. Controller 54 is also operative in response to operator commands entered via control panel 50 and to temperature sensor 56 to control heater 52 to heat the circulating air to a desired temperature.
Referring to FIGS. 1, 2, 4 and 5, jet plate 72 comprises a plurality of jet nozzles 100 arranged in staggered rows and columns. It is contemplated that other patterns and shapes of jet nozzles 100 and insert 102 may be used. Jet nozzles 100 are shaped to provide high velocity shapes of hot or cold impingement air toward oven rack 84. Disposed in each jet nozzle 100 is a nozzle insert 102 that is shaped to provide a predetermined air flow pattern 104. Nozzle insert 102 preferably has a shape that generates a bell shaped flow pattern, which is relatively thin or has a thickness so as to generate overall flow pattern at the surface of the food product that enhances the heat transfer to the product. In consequence, the heat transfer pattern is more homogeneous at the food product and/or bottom wall 40. This leads to a more homogeneous and high heat transfer distribution, which leads to accelerated but homogeneous cooking of food products in oven 30 as well as other types of ovens (e.g., conveyor ovens, industrial ovens, laboratory ovens, residential ovens and the like) where guided hot or cold airflow is used for convection heating and cooling. Nozzle insert 102 is preferably cone shaped to produce the bell-shaped airflow pattern 104. Nozzle insert 102 may be either solid or hollow. Nozzle insert 102 is disposed within jet nozzle 100 to form about nozzle insert 102 a slot-shaped orifice 126 through which the impingement air flows.
Compared to traditional jet nozzles, the bell shaped flow pattern is a function of the “contact” surface between the fluid or air in motion and the air not in motion and is much greater. Therefore, shear stresses show stronger effects, which means that vortices occur and the point of transition from laminar air to turbulent air moves further up-stream. towards the nozzle which results in a stronger turbulence level down-stream of the jet nozzle toward the food product. The nozzle insert of the present disclosure advantageously leads to wider nozzle spacing and reduced distance between impingement plate 72 and the surface of the food product to achieve a more homogeneous air flow pattern. In some embodiments, the jet nozzles and jet inserts can be larger so that fewer are needed, which may allow the space between jet plate 72 and the food product to be greater. The present disclosure contemplates that many embodiments are possible based on the size and shape of jet nozzle 100 and nozzle insert 102 and spacing may be increased as well.
Referring to FIG. 6, a portion of jet plate 72 is shown with a bracket assembly 110 for attaching nozzle insert 102 to jet plate 72. Bracket assembly 110 comprises a bridge like structure comprising base portions 112 and 114 that are connected to ramp sections 116 and 118, respectively, which are connected to a top portion 120. Base portions 112 and 114 are attached to a top side of jet plate 72 by any suitable fastener, such as a weld, an adhesive, screw, bolt and the like. A stem 122 is attached at one end to nozzle insert 102 and at a distal end to top portion 120 of bracket assembly 110 by a bolt 122 or other fastener, such as a weld, adhesive and the like. In one embodiment, stem 122 and nozzle insert 102 are formed as an integral or unitary part. In one embodiment, the distal end may carry screw threads that screw into mating screw threads in a properly aligned hole in top portion 120, thereby allowing for vertical adjustment of nozzle insert 102 to vary the vertical position of nozzle insert 102 with respect to jet nozzle 100. Nozzle 100 reduces pressure losses at the leading edge and guides the airflow smoothly.
The present disclosure contemplates that the nozzle insert may have different shapes to provide different airflow patterns such as those shown in FIGS. 7-12. Nozzle insert 130 in FIG. 7 has filled margarita glass shape. Nozzle insert 140 in FIG. 8 has an upside down filled wine glass shape. Nozzle insert 150 in FIG. 9 has a pedestal shape. Nozzle insert 160 in FIG. 10 has a Maraca shape. Nozzle insert 170 in FIG. 11 has a mirrored pedestal shape. Nozzle insert 180 in FIG. 12 has a filled wide bell shape. These are examples of nozzle and insert shapes and this disclosure is not limited to circular and conical shapes.
A shape of the slot-shaped orifice is selected from the group consisting of: curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.
A shape of the nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.
It is contemplated that the convective airflow of the present disclosure may also be used in cooling applications as well as in heating applications. The present disclosure having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present disclosure and appended claims.

Claims

1. An oven comprising:

an oven chamber and a blower that is disposed to circulate air through said oven chamber;

an air impingement plate that is disposed in said circulating air and that is located to provide impingement air toward a product in said oven chamber, and

at least one jet nozzle that is disposed in said impingement plate and a nozzle insert disposed in relation to said jet nozzle to form about said nozzle insert a slot-shaped orifice through which said impingement air flows.

2. The oven of claim 1, wherein a shape of said slot-shaped orifice is selected from the group consisting of: curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.

3. The oven of claim 1, wherein a shape of said nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.

4. The oven of claim 1, wherein said slot-shaped orifice has a thickness that produces an overall flow pattern at the surface of said product that enhances heat transfer to said product and a homogeneous heat transfer at a surface of said product.

5. The oven of claim 1, wherein said nozzle insert is selected from the group consisting of: solid and hollow.

6. The oven of claim 1, wherein a shape of said jet nozzle is selected from the group consisting of: a match with a shape of said nozzle insert and a non-match of a shape of said nozzle insert.

7. The oven of claim 1, wherein said jet nozzle is one of a plurality of jet nozzles that each have an associated nozzle insert in relation to said jet nozzle to form about said nozzle insert a slot-shaped orifice through which said impingement air flows, and wherein said plurality of jet nozzles collectively provide a homogeneous and high heat transfer distribution at said product.

8. The oven of claim 1, wherein a temperature of said air is controlled by a unit selected from the group consisting of: heating and cooling.

9. The oven of claim 1, further comprising a fastener that fastens said nozzle insert to said impingement plate to vary an axial position of said nozzle insert relative to said impingement plate.

10. The oven of claim 1, further comprising a heater disposed to heat said circulating air, and wherein said product is a food product.

11. A method of operating an oven comprising:

circulating air in an oven chamber;

providing an impingement plate in said circulating air to provide impingement air toward a product in said oven chamber; and

shaping said impingement air with a slot-shaped orifice through which said impingement air flows.

12. The method of claim 11, wherein a shape of said slot-shaped orifice is selected from the group consisting of: curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.

13. The method of claim 11, wherein a temperature of said air is controlled by a unit selected from the group consisting of: heating and cooling.

14. The method of claim 11, further comprising a heater disposed to heat said circulating air, and wherein said product is a food product.

15. The method of claim 11, wherein at least one jet nozzle is disposed in said impingement plate and a nozzle insert is disposed in relation to said jet nozzle to form about said nozzle insert said slot-shaped orifice through which said impingement air flows.

16. The method of claim 15, wherein a shape of said nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.

17. The method of claim 15, wherein said slot-shaped orifice has a thickness that produces an overall flow pattern at the surface of said product that enhances heat transfer to said product and a homogeneous heat transfer at a surface of said product.

18. The method of claim 15, wherein said insert is selected from the group consisting of: solid and hollow.

19. The method of claim 15, wherein a shape of said jet nozzle is selected from the group consisting of: a match with a shape of said nozzle insert and a non-match of a shape of said nozzle insert.

20. The method of claim 15, wherein said jet nozzle is one of a plurality of jet nozzles that each have an associated nozzle insert in relation to said jet nozzle to form about said nozzle insert a slot-shaped orifice through which said impingement air flows, and wherein said plurality of jet nozzles collectively provide a homogeneous and high heat transfer distribution at said product.

21. The method of claim 15, further comprising a fastener that fastens said nozzle insert to said impingement plate to vary an axial position of said nozzle insert relative to said impingement plate.

22. A jet nozzle that is disposed in an air impingement plate and at least one nozzle insert disposed in relation to said jet nozzle to form about said nozzle insert a slot-shaped orifice through which impingement air flows.

23. The jet nozzle of claim 22, wherein a shape of said slot-shaped orifice is selected from the group consisting of: curvilinear, ring, annular, polygonal, square, rectangular, elliptical, multi-point, jack and cruciform.

24. The jet nozzle of claim 23, wherein a shape of said nozzle insert is selected from the group consisting of: bell, goblet, cone, margarita glass, upside down filled wine glass, pedestal, maraca, mirrored pedestal, and filled wide bell.

25. The jet nozzle of claim 24, wherein a shape of said jet nozzle is selected from the group consisting of: a match with a shape of said nozzle insert and a non-match of a shape of said nozzle insert.

26. The jet nozzle of claim 22, wherein said nozzle insert is selected from the group consisting of: solid and hollow.

27. The jet nozzle of claim 22, further comprising a fastener that fastens said nozzle insert to said impingement plate to vary an axial position of said nozzle insert relative to said impingement plate.