GB2388425A

GB2388425A - A convection oven

Info

Publication number: GB2388425A
Application number: GB0210788A
Authority: GB
Inventors: Lazzer Natalino
Original assignee: Lainox Ali SpA
Current assignee: Lainox Ali SpA
Priority date: 2002-05-08
Filing date: 2002-05-11
Publication date: 2003-11-12
Anticipated expiration: 2022-05-11
Also published as: GB2388425B; FR2840057B3; DE10220625A1; GB0210788D0; NL1020570A1; FR2840057A1; NL1020570C2

Abstract

A convection oven has a chamber 7 housing a fuel burner 71 leading to a fume distribution chamber 8 which leads to exchanger pipes 9 for the evacuation of combustion fumes, wherein preferably, the chamber 7 is at the bottom of the oven, below and in communication with the distribution chamber 8, which is directly connected to exchanger pipes 9 that extend upwardly in two groups either side of a fan 6 to a manifold that precedes a chimney. The exchanger pipes may have a curve in the upper part followed by a short section to join them to the manifold 10. The distribution chamber may be longer in length than the diameter of the fan. Valves may be present at an opening to the distribution chamber 8 and chimney 101. A logic unit may control the working of the oven.

Description

4 Structure for gas oven, of the convection type, with highefficiency, S

particularly for food cooking.

12 This invention relates to a convection oven structure for the 3 cooking of food.

14 The innovation has particular though not exclusive application 15 in the commercial catering gas oven sector.

16 Background of the invention

17 It is well known that the needs, in the commercial catering 18 sector, are generally different from those which we usually have 19 domestically. Indeed, other than the huge quantity of food that has 20 to be cooked at once, other factors come in that should to a 21 greater extent characterize the cooking equipment, such as for 22 example a good thermal performance for a quicker and more even 23 cooking, together with the guarantee of assuring a reasonable 24 saving on consumption. These values, for example, can be derived in 25 a traditional gas type convection oven, by the rational exploitation

( 1 of burning fumes generated by the burner, which, forced within tube 2 bundles go to constitute the exchanger. This exchanger, placed with 3 a related fan in an interspace communicating with the cooking 4 chamber, is licked by the generated air-flow, favouring in this way a S continuous redistribution of hot air in the cooking chamber where 6 the pans have been previously introduced, maintaining an even and 7 at the same time optimal temperature in each point.

8 In the past, there has been great progress in the gas oven 9 industry, some of which deserves to be briefly mentioned.

10 Prior art

11 A first step forward, for example, was made by the solution 12 described in US3605717 (Sauer). In it, a convection oven is 13 described, essentially divided in two areas from a separating 14 septum, in one of which the fan group is present. The adjoining 15 section, on the other hand, comprises the cooking chamber, in 16 communication with the first area through an intake, which by 17 means of the interposition of a conic manifold, precedes the fan. To 18 maximise the performance of the oven, a single pipe carrying a fluid 19 in temperature is also provided, which develops for almost 360 20 around the conic manifold that precedes the said fan.

21 The solution, even though it does bring improvements, has 22 not proved convincing, considering the fact that the air is heated 23 before the fan can make it circulate again, provoking in this way a 24 loss in the temperature performance otherwise obtainable.

1 US4648377 (Van Camp) solves the problem. In it, 2 substantially, a convection oven like the previous one is described, 3 but this time, the pipe affected by the fluid is placed around the fan, 4 rather than in proximity or upstream of the sucked airflow.

S Additionally, said solution contemplates the winding of the fan 6 following a development closer to 360 than the one proposed 7 previously by Sauer.

8 However, even before US4648377 (Van Camp), there have 9 been many other attempts to optimise the performance of the 10 convection oven, amongst which IT108723 1 (Foemm) seems 11 interesting. This, briefly, is about a hot air circulation oven, 12 particularly for food-cooking. In it, the burnt fumes pipes are 13 collected in a chamber, adjoining the cooking chamber, and placed 14 on each side of the tubular manifold that connects the two 15 chambers and at the same time fits into the fan. The pipes carrying 16 the fumes, in this case, extend themselves vertically from a 17 combustion chamber placed immediately below, or at the base of, 18 said pipes, up to an upper manifold from which the fumes pass 19 through a chimney to be expelled. Also in this case, the hot air 20 circulation, during the working of the oven, is obtained through a 21 closed cycle. The air is sucked from the cooking chamber and, 22 flowing through the manifold that leads to the fan, is redistributed 23 to lick the external surface of the fume pipes and is then, after 24 having absorbed heat, forced to transit again through the cooking 25 chamber. The solution revealed itself effective at once, however, it

1 could be still improved as far as performance and a more even 2 temperature distribution.

3 In these terms IT1158054 has intervened (Lainox), proposing -

4 a considerable improvement in the sector and particularly regarding the said oven. More particularly Lainox's solution is substantially 6 different from Foemm's, for the particular arrangement and shape 7 of the tube bundles through which the burnt fumes flow, 8 incrementing their calorific performance. in further detail, a lower 9 combustion chamber is provided, to which the lower ends of the 10 tube bundles are joined longitudinally and on the top side. These 11 stretch out upwards, and are divided in two groups, one for each 12 side of the fan, and form, in an intermediate position, a semicircular 13 shape, in such a way as to wrap, on both sides and partially, the 14 fan. Finally the higher ends of the tube bundles end in a common 15 interspace, obtained on the upper part of the oven, which is 16 provided, centrally, with a chimney for the evacuation of the burnt 17 fumes. Lainox's proposal revealed itself particularly effective at 18 once, so much that different firms of the sector, in different ways, 19 exploited its teachings.

20 It is furthermore well known that the companies of the 21 sector are always searching for improvements, thus in order to 22 make the performance of the convection oven even more effective, 23 EP0526768 (Zanussi) describes equipment which provides for the 24 distribution of the pipes that evacuate the burnt fumes all around 25 the traditional fan, rather than partially. More particularly, in an

1 area adjoining the cooking chamber, a fan is provided for the blow 2 by of the air in the cooking chamber, a pipe developed at 360 runs 3 along the perimeter of this fan, through which the burnt fumes flow 4 to be evacuated. In this case, in correspondence with the intake of 5 the pipe, a burner that works together with an upstream turbine is 6 provided, its action forcing the heated air to flow through the way 7 resulting from the single shaped pipe. This pipe, after having carried 8 out a complete turn around the fan, makes another half turn, and 9 then protracts itself with a rectilinear section on the outside of the 10 oven, where the evacuation of the fumes is allowed.

11 Finally, a change in the previously described solution is also 12 known, of which we do not agree with the presumed advantages.

13 More in detail, DE19708231 (Rational) also suggests a particular 14 exchanger, which provides a burner placed at one end of the tube 15 that allows, after a short way, the evacuation of burnt fumes. The 16 pipe, in this case, carries out a first route one way, around the said 17 fan, and comes back along another way almost parallel to the first, 18 preceded by an elbow bend, without completing the winding of the 19 fan. 20 Drawbacks 21 The analysed proposals undoubtedly have their values, but 22 also some defects. Therefore, if on the one hand Sauer, Van Camp, 23 Foemm and Lainox, suggest solutions of a technical nature, for 24 those years, unable to use the possible thermal exchange deriving 25 from the cooperation between fan and tube bundles placed in

1 proximity of the former in an optimal way, on the other Zanussi and 2 Rational, retaking the concept of the firsts, surely optimise the 3 efficiency of the exchanger, albeit a particularly complex realization 4 of the system. This, as a rule, imposes particularly high production 5 costs, and sometimes, due to complex phenomena, an effectiveness 6 lower than expectations.

7 For these and other reasons, in conclusion, we see the need

8 to find alternative and at the same time better proposals than the 9 techniques adopted up to now.

10 Brief description of the invention

11 These and other purposes are achieved with this innovation 12 according to the characteristics as set out in the included claims, 13 solving the described problems with a gas type convection oven for 14 food-cooking which includes a cooking chamber, accessible on one 15 side by means of a door, adjoined by a technical compartment in 16 communication with the first, containing at least one fan whose 17 relative movement members work with the logical unit that 18 manages the working of the oven, said fan being peripherally 19 interested by close tube bundles for the evacuation of burnt fumes 20 coming from a burner, and furthermore in which in the underside of 21 the oven an expanding chamber that houses the burner is provided, 22 said expanding chamber being in communication with a fumes 23 distribution chamber placed above it to which the lower ends of 24 said tube bundles that protract upwards are connected, along the

1 sides of the fan, to then meet in a common manifold, that conducts 2 to an evacuation chimney provided in the upper part of the oven.

3 Advantages 4 In this way, through the considerable creative contribution S which effects constitute an immediate and undeniable technical 6 progress, different and important objectives are achieved.

7 A first purpose has been to obtain an oven with a high 8 calorific performance, able to optimise the even distribution of hot 9 air inside the cooking chamber, which helps a correct and faster 10 cooking of introduced food. More particularly, as regards to a 11 comparison with some of the previous solutions, such as the 12 Zanussi and Rational proposals, one observes a considerable 13 increase in the thermal exchange surface deriving from the presence 14 of the horizontal expanding chamber placed at the bottom of the 15 fan. 16 A second purpose consists in providing a convection oven, 17 that compared to previous solutions, with an equal kilo/calories 18 ratio, is able to reasonably contain consumptions.

19 A third purpose has been reached by making a convection 20 oven with an internal structure that provides for an interaction of 21 the exchanger with the fan, that is not particularly complex from a 22 constructional point of view, allowing to contain production costs 23 within acceptable limits without having to interfere with the overall 24 qualify of the oven.;

1 A fourth purpose, with all evidence, consists in presenting an 2 oven with a particularly robust internal structure, able to resist 3 over time to the thermal expansions noticeable, particularly in 4 previous solutions, in correspondence of the connection of the tube 5 bundles, as the under chamber directly housed the burner body.

6 In conclusion, these advantages have the all but negligible

7 value of obtaining an oven with a good technological content, 8 functional for its high performance and extremely reliable, even in 9 particular working conditions.

10 These and other advantages will appear from the following 11 specific description of a preferred solution with the aid of the

12 attached schematic drawings whose details of execution are not to 13 be considered limitative but only and exclusively illustrative.

14 Description of the drawings

15 1. Figure 1. is a front view and in section on a transversal plane of 16 the convection oven, according to the axis A-A of Figure 3.

17 2. Figure 2. represents a bird's eye view of the convection oven.

18 3. Figure 3. is a side view of the convection oven of Figure 1.

19 Description of an execution of the inventio

20 The present solution refers to a convection oven (A) for 21 foodcooking. More particularly said oven (A) is composed of an 22 external body ( 1) for support and coating, essentially 23 parallelepiped, inside which a capacious cooking chamber is 24 obtained (Z). One accedes to the cooking chamber (2), provided at

1 the bottom (21) with a discharge (22), through a door (3) at the 2 front end, hinged sideways.

3 Adjoining the cooking chamber (2), in this case in the back, a 4 interspace or technical compartment (4) in communication with the s first (2), is obtained. In more detail, a septum (5) distinguishes the 6 two areas (2, 4), interested centrally by a portion deformed as a 7 manifold of conic entrance (51) which coincides with the position of 8 the back fan (6) housed on the inside of the technical compartment 9 (4). In even further detail, the underside of the oven (A) in 10 correspondence with the technical compartment (4), is interested 11 by a fumes expanding chamber (7), inside which the combustion 12 fumes out generated by the activity of the burner (71) expand. In 13 this case, one observes that said burner (71) is housed at one of 14 the two ends of the expanding chamber (7). As regards the 15 proportions of said expanding chamber (7), one detects that in a 16 solution it presents a width almost corresponding with the depth of 17 the technical compartment (4) provided in the back part of the 18 oven (A), while the length almost coincides with the width of said 19 technical compartment (4).

20 Immediately above the said expanding chamber (7), there is 21 a second, less capacious, chamber (8), in communication with the 22 first (7). In more detail, the second chamber (8) has the function of 23 distributing the fumes that come from the underlying chamber (7) 24 and pass through the opening (81). The said opening (81) in a case 25 is likely to be intercepted by a valve that regulates the flow of

1 fumes. The chamber (8) presents a development in length at least 2 sufficient to protract and exceed, on both sides, the above placed 3 fan (6). In this way, in correspondence with the right and left ends 4 (82), respectively, of the distribution chamber (8), the lower ends 5 (91) of two groups of pipes or side tube bundles (9) fit in. In the 6 described solution, three pipes (9) correspond to each group, 7 arranged on both sides of the fan (6), each one extending vertically, 8 connecting the underlying distribution chamber (8) to the exhaust 9 manifold of the fumes (to), provided centrally and on the upper 10 part of the technical compartment (4). As the said groups of pipes 11 (9) are placed at the sides of the fan (6), each of them is shaped 12 on the upper part with a 90 curve (92), in such a way that they 13 then proceed horizontally for a short section, compensating the 14 distance needed to arrive in correspondence of the manifold (10).

15 Finally, the fumes flowing through the manifold (10), reach a 16 chimney (101) dispersing into the environment, that protrudes 17 above the top-side of the oven (A), which can be eventually 18 interested by the action of a interception valve.

Claims

1. Convection oven structure for food cooking, wherein is provided, between an expanding chamber that houses at least one fuel burner and 5 the entrance of exchanger pipes for the evacuation of combusted fumes, at least one distribution chamber for said burnt fumes.

2. Convection oven structure for food cooking, according to claim 1, wherein the bottom of the oven in correspondence with a technical 10 compartment includes the expanding chamber, inside which the burnt fumes out generated by at least one burner expand, and in which, above the expanding chamber, is the distribution chamber for burnt fumes, in communication with the said expanding chamber through at least one connecting opening.

3. Convection oven structure for food cooking, according to claim 1 or claim 2, wherein lower ends of the exchanger pipes placed at least at one of two sides of a fan, fit into the distribution chamber 20

4. Convection oven structure for food cooking, according to any preceding claim wherein the exchanger pipes are connected at an upper part to a manifold that precedes a chimney.

5. Convection oven structure for food cooking, according to claim 3 25 or claim 4 as dependent from claim 3, wherein the exchanger pipes extend upwardly, divided in two groups, along the sides of the fan.

6. Convection oven structure for food cooking according to claim 4 or claim 5 as dependent from claim 4, wherein each exchanger pipe is 30 shaped at least at the upper part with a curve, followed by a short section joining it to the manifold.

7. Convection oven structure for food cooking, according to any preceding claim, wherein an or the opening giving access to the burnt fumes distribution chamber, is intercepted by a valve that regulates the flow of the fumes. t

8. Convection oven structure for food cooking, according to claim 5 or either of claims 6 and 7 as dependent from claim 5, wherein the distribution chamber presents a development in length longer than the diameter of the fan, so that in correspondence with opposite ends, 10 respectively, of the distribution chamber, lower ends of the two groups of exchanger pipes fit therein.

9. Convention oven structure for food cooking, according to claim 5 or claim 8, wherein the exchanger pipes, on both sides of the fan, 15 correspond in both groups of the exchanger pipes, each exchanger pipe extending perpendicularly to the distribution chamber, connecting the distribution chamber to the manifold for the fumes, provided at the upper part of a or the technical compartment.

20

10. Gas oven of the convection type for food cooking, which comprises: - a cooking chamber, accessible on one side by means of a door; - an adjoining technical compartment in communication with the cooking chamber; 25 - a fan contained within the technical compartment whose relative movement members cooperate with a logic unit that manages the; - exchanger pipes for the evacuation of burnt fumes generated by at least one burner, which develop sideways, divided in two groups 30 along opposite sides of the fan;

- a chimney in communication with the exchanger pipes, and in the bottom of the oven an expanding chamber that houses the burner, said expanding chamber being in communication with a fumes t distribution chamber above it, to which lower ends of said 5 exchanger pipes are connected, and then extend upwards, along the opposite sides of the fan, to meet, in the upper part of the oven, a common manifold that leads to an evacuation chimney.

11. Convection oven structure for food cooking, according to any of 10 claims 1 and 9 or a gas oven according to claim 10 wherein in correspondence of a or the chimney an interception valve is provided. i

12. A convection oven structure for food cooking substantially as described herein with reference to the accompanying drawings.