WO2014044766A1

WO2014044766A1 - Method for operating an oven, and oven

Info

Publication number: WO2014044766A1
Application number: PCT/EP2013/069495
Authority: WO
Inventors: Konrad SCHÖNEMANN; Michael Riffel; Christian Seidler
Original assignee: E.G.O. Elektro-Gerätebau GmbH
Priority date: 2012-09-21
Filing date: 2013-09-19
Publication date: 2014-03-27
Also published as: DE102012217054A1

Abstract

In a method for the pyrolysis cycle of an oven (11), hot air is blown into a muffle (12) of the oven, wherein hot air is applied in a targeted manner to regions of the muffle requiring intensive cleaning, such as the underside, down in the corners, at the edges and the inside of an oven door (14), in addition to the other blowing of hot air into the muffle. Hot air can be applied variably and from different directions by means of variable nozzles (17a, 17b). Hot air can be applied alternately to a plurality of regions requiring intensive cleaning.

Description

description

Method of operating an oven and oven Application area and state of the art

The invention relates to a method for operating a baking oven in the pyrolysis operation and an oven designed for carrying out this method. Such a pyrolysis operation serves to increase the temperature in the muffle of the oven well above a normal operating temperature, for example 450 ° C or more, with hot air being blown into the muffle for this purpose. At these temperatures, organic pollutants and residues burn and incinerate, so they can easily be removed.

A pyrolysis operation for cleaning a baking oven of soiling or deposits on the walls is known, for example, from DE 41 14909 C2. For example, while a heating element in the oven, such as a grill heater, permanently operated without timing until the desired or aforementioned high temperatures for the pyrolysis in the muffle are reached and burn and ashes organic dirt and residues. In this case, a duration of the pyrolysis operation and a necessary use of energy can be very high. In some areas, such as a oven door, the desired temperature for the pyrolysis can only be achieved incompletely or not at all due to poor thermal insulation to the outside.

Task and solution

The invention has for its object to provide a method mentioned above and an oven suitable for carrying out this method, with which problems of the prior art ge can be solved and it is particularly possible to achieve the best possible cleaning of the oven in pyrolysis and in particular to be able to reduce duration and / or energy consumption. This object is achieved by a method having the features of claim 1 and an oven with the features of claim 1 1. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features are described only for the process or just the oven. However, they should be able to apply independently for both the process and for the oven independently. The wording of the claims is incorporated herein by express reference. According to the invention, during pyrolysis operation, areas of the muffle which are particularly intensive for cleaning, such as their underside, the lower corner areas, the inner edges and the inside of a baking oven door, are at least partially exposed to hot air in addition to the other injection of hot air into the muffle. In fact, these named intensive cleaning areas are usually very critical or usually very intensive in terms of cleaning, since they pollute more strongly in principle and because of the design, in particular the underside, or can be poorly cleaned, such as the lower corner areas or inner edges. Finally, just as explained above, an inside of a baking-oven door can be poorly achieved or cleaned in normal pyrolysis operation. This targeted application of hot air should therefore take place in addition to operation with the normal fan of the oven, if this is a hot air oven. There are advantageously provided separate openings or nozzles for this targeted application of hot air. Furthermore, at least one additional fan is advantageously provided for this targeted application. In a first basic embodiment of the invention, it is possible that the targeted application of hot air is fixed or is immutable in their direction, so always aligned the same. Such alignment is directed, for example, into the aforementioned areas of the lower corner areas, on the underside or in the areas of the inner edge. For this purpose, fixed nozzles or rigid nozzles can advantageously be provided. In extension of the invention it can be provided that at least some of these nozzles are closable and also be closed for selectively stopping the blowing hot air. Thus, for example, when supplying the nozzles with a single additional fan whose power is not sufficient for all nozzles simultaneously to generate practical application of hot air for said cleaning intensive areas whose air flow at the same time always be guided by only one or a few nozzles the oven muffle into or on the said critical areas. Thus, as a result, a quasi-movable jet of hot air can be created, even if the mobility is not infinitely or arbitrarily. In a second basic embodiment of the invention, the admission of said cleaning intensive areas with hot air is variable or directionally variable, that is advantageous with movable nozzles. This makes it possible to apply a plurality of cleaning-intensive areas successively or alternately with a hot air flow, namely by this is moved, so to speak, directly and continuously. This hot air stream should advantageously be small in relation to the size of the respective cleaning-intensive area or approximately its size, at least with respect to the lower corner areas. As a result of the variable or directionally variable application of the hot air flow, smaller areas subject to intensive cleaning can be repeatedly acted upon one after the other in a targeted manner. This alternating targeted action on the additional hot air ensures sufficient pyrolysis and cleaning.

With regard to large-scale cleaning-intensive areas such as the underside of the muffle and the inside of the oven door, the air flow can not cover the entire area in a single direction setting or heat accordingly. Here, it is possible to introduce hot air in such a way that a hot air flow is created, which virtually scans the area of cleaning-intensive areas. So these areas can be successively acted piece by piece in a grid with the hot air or the hot air flow. Overall, it is possible that only a single additional hot air flow is provided, which is variable in its direction and thus can be aligned. It can successively travel down the lower corner areas, for which a movement of the airflow per corner area is not necessary. Then he can also drive off the inner edges, for which he advantageously along appropriate lines. Finally, the large areas such as bottom and inside of the oven door can be scanned as described above. Then in turn can be started again with the lower corners.

In a further embodiment of the invention, it is possible that, so to speak, two additional fans are provided for two additional air streams. This not only generally increases the ability to clean the interior of the muffle with two hot air streams. Rather, if variable or directionally variable nozzles are used, in each case one can be provided in two opposite side walls. These can then act on the opposite lower corner areas particularly well with the hot air flow.

Preference is given to a targeted application of cleaning-intensive areas with hot air from above or with a directional component from top to bottom. It can thus be taken into account that eil the lower areas of the muffle are intensive cleaning. Furthermore, it is then possible that corresponding nozzles are provided approximately at half the height in the muffle in the side walls and they are thus relatively well protected against direct contamination.

For the variable or directionally variable nozzles advantageously controllable drive means may be provided. These can be on the one hand directly controllable actuators such as an electric motor or an electromagnet. Furthermore, it may be controllable bimetal actuators, which are provided with a controllable heater for adjustment.

These and other features are apparent from the claims and from the description and the drawings, the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and for can represent protectable versions for which protection is claimed here. The subdivision of the application into individual sections as well as subheadings does not limit the statements made thereunder in their general validity.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings scheme table and are explained in more detail below. In the drawing calculations show:

1 is a schematic front view of a baking oven according to the invention with additional nozzles for targeted loading of cleaning-intensive areas with hot air,

2 is a side view of the oven of FIG. 1 with additional additional nozzles, 3 and 4 directionally variable nozzles for the introduction of hot air,

Fig. 5 is a plan view of a hot air duct with only one fan and a plurality of additional nozzles and

Fig. 6 is a closable nozzle for hot air in an enlarged view.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS FIG. 1 shows a baking oven 11 according to the invention with a muffle 12 in which a heating element 13 is arranged as a conventional grill heater. The oven 1 1 still has a conventional fan 15 on a rear wall of the muffle 12, as used for the usual hot air operation and also for a pyrolysis operation described above.

Furthermore, an additional nozzle 17a is provided on a left side wall of the muffle 12, and an additional nozzle 17b is provided on the bottom right of the rear wall of the muffle. These each have an additional fan 18a and 18b. At the left additional nozzle 17a, an upper baffle 20a and a lower baffle 22a are clearly visible. It can be clearly seen, especially in the case of the additional nozzle 17a, that it is directed obliquely and rather flat downwards, so that a jet of hot air emerging from it runs downwards and flows downwards along the bottom of the muffle 12. In particular, the additional nozzle 17a is arranged at the rear in the muffle near the rear wall and oriented so that the flow of hot air flows in the rear lower throat between the rear wall and the bottom of the muffle around this particularly cleaning-intensive or hard to reach area above-mentioned way to clean particularly intensively.

The right additional nozzle 17b is also inclined downwardly and slightly outwardly. The outgoing air stream sweeps in the Throat between the right side wall and the bottom of the muffle 12 along, as well as a corresponding cleaning-intensive or critical and difficult to reach area is given. In the left side view according to FIG. 2, the main fan 15 and the additional nozzle 17b together with additional fan 18b can be seen. Furthermore, two further additional nozzles 17c and 17d, each with an additional fan 18c and 18d, are arranged on the right side wall of the muffle 12. These additional nozzles 17c and 17d are directed against the inside of the oven door 14 to also clean them by producing a sufficiently high temperature on the door. Thus, a usually higher heat loss at the oven door 14 can be compensated, as has been explained above, so that also takes place here a good cleaning by means of pyrolysis. Similar additional nozzles for the oven door 14 may also be provided on the left side wall of the oven.

In Fig. 3, a lower additional nozzle 1 17 is shown in a lateral view, through which the lower additional fan 1 18 blows hot air into the muffle. An upper baffle 132 is, as indicated in the drawing, made of a bimetal and has a certain shape or orientation at a certain temperature. This also applies to a lower baffle 133. Together they direct the flow of hot air, in the present case at a shallow angle obliquely to the bottom right.

In order to achieve an adjustability of the baffles 132 and 133 and thus the direction of the injected air, a heating 135 is provided by way of example for the upper baffle 132, which may also be present on the upper baffle 133. It is symbolized here by a meandering loop of a heater, such as a tubular heater. As a result of its arrangement very close to the upper baffle plate 132, this can bring about a strong heating of the same and thus bend or deflect it in the desired direction, as it were. For example, down to the position shown in dashed lines. So this is a kind of controllable baffle or controllable additional nozzle 1 17, being dispensed with articulated or freely movable parts. 4, an alternative of a lower additional nozzle 217 is shown with a lower additional fan 218, wherein articulated movable parts are provided here. An upper baffle 220 and a lower baffle 222 are arranged with their respective left end hinged to a side wall of the muffle 212. Furthermore, they are connected to each other via a guide rod 237 for substantially synchronous movement. The upper baffle 220 is extended to the left and is pivoted at its end by a piston rod 239 of an actuator 240 by its movement upwards or downwards. The actuator 240 may be a substantially arbitrarily designed linear drive, for example as an electric motor or as a coil or solenoid with a movable piston therein. Above all, electromagnetic coils can be made relatively resistant to temperature and have only a few moving parts, so that they are very robust. The actuator 240 may move the baffles 220 and 222 up and down to the dashed positions so that the hot air of the fan 218 is adjustable within wide limits with respect to the blowing angle or direction and thus the area of the walls of the muffle 212 is. Alternative embodiments of adjustable additional nozzles are round nozzles with oblique orientation, which are rotatable. Due to its oblique orientation, the direction of the blown-out hot air can be changed or adjusted by rotating the nozzle, for example with a previously described actuator, within its holding plane in the muffle wall.

While in the previous illustrations in FIGS. 1 to 4 each per nozzle or per additional nozzle its own additional fan dar- can be reduced, the number of additional fans can be reduced to save on unnecessary unnecessary effort. This is shown in Fig. 5, which may represent, for example, a plan view of another oven according to the invention 31 1. There, a plurality of additional nozzles 317a to 317e are provided on a muffle 312, which are connected to one another by means of a single air channel 319 or are supplied with air for blowing into the muffle 312 by a single additional fan 318. This could even be the only fan 15 from FIG. The individual additional nozzles 317a to 317e are each aligned with critical or cleaning-intensive areas in the muffle 312, which is not shown in detail here, but is easy to imagine. Alternatively, they may be partially or all controllable, for example, as shown in FIGS. 3 and 4. In the embodiments of FIGS. 1 to 4, each with an additional fan per additional nozzle, an aforementioned operation per additional nozzle is easily controllable, namely by the additional fan works or not. Furthermore, there is of course a very high fan performance due to the large number of additional fans, depending on the performance of each individual fan.

In the embodiment of FIGS. 5 and 6, this is different, since just a single additional fan 318 is provided. It is either sufficiently large or powerful enough for a sufficient introduction of hot air through all additional nozzles 317a to 317e. Alternatively, at least some of these additional nozzles 317a to 317e may be closable so that hot air is only blown through some of them and thus a stronger hot air jet is achieved. This is shown in Fig. 6 in enlargement for the additional nozzle 317b. The additional nozzle 317b is connected to the circumferential air channel 319 and has an indicated upper baffle 320 and a lower baffle 322. The opening formed therebetween can be closed by a slide 324, which is shown in Fig. 6 open or drawn pulled down. The slide 324 is connected to a piston rod 325 of an actuator 326 in the manner of a linear drive. Advantageously, this actuator 326 is an electromagnet with linearly movable piston rod 325 in it, as the skilled person knows sufficiently. Other actuators are easily conceivable, for example, those of Figs. 3 and 4.

The actuator 326 can move the slide 324 to the dashed position or completely upwards, so that the additional nozzle 317b is closed and hot air can not flow out here. Alternative possibilities for closing the additional nozzle 317b would be a plurality of lamellae arranged next to one another, which can be pivoted about a respective parallel axis of rotation, similar to the guide plates according to FIG. 4. If they are pivoted maximally toward one another, they close an additional nozzle. In a swivel angle of 90 ° to this closed position, the air flows directly into the muffle. With such embodiments, some control of the direction of the hot air flow can also take place. If all the additional nozzles 317a to 317e according to FIG. 5 are provided with sliders according to FIG. 6 or other closing means, the entire hot air jet generated by the fan 318 can be applied alternately or at one time only to one of these nozzles for particularly intensive pyrolysis treatment that area to which the respective nozzle is aligned. Alternatively, of course, it can also be any number of nozzles.

For a targeted admission of a region within the muffle with hot air heating times are to be considered sufficient, which may be for example one or two or even a few minutes. In view of a total duration of a pyrolysis operation of a few hours, for example 2 hours to 4 hours, even in the case of a change as described above, the cleaning-intensive areas can Frequently and / or combined for a sufficiently long time, targeted hot air can be applied for better pyrolytic cleaning. Furthermore, this very long pyrolysis time can be shortened due to the targeted charging according to the invention, since these difficult-to-clean places cause or dictate these long process times. So both time and energy can be saved.

Claims

Patent claims

1. A method for operating an oven in pyrolysis mode, whereby hot air is blown into a muffle of the oven, characterized in that particularly cleaning-intensive areas of the muffle such as the underside, the bottom in the corners, edges and the inside of an oven door are specifically exposed to hot air in addition to otherwise blowing hot air into the muffle.

2. The method according to claim 1, characterized in that the targeted application of hot air is fixed or unchangeable in the direction, in particular by means of fixed nozzles.

3. The method according to claim 2, characterized in that the targeted application of hot air by means of fixed nozzles is fixed or unchangeable in the direction.

4. The method according to claim 2 or 3, characterized in that at least some of the nozzles can be closed to selectively stop the injection of hot air.

5. The method according to claim 1, characterized in that the exposure to hot air is variable or changeable in direction.

6. The method according to claim 5, characterized in that the application of hot air by means of variable nozzles is variable or changeable in direction.

7. Method according to one of the preceding claims, characterized in that several cleaning-intensive areas one after the other or alternately with a stream of hot air.

8. The method according to claim 7, characterized in that the hot air flow is relatively small in relation to the size of the cleaning-intensive area.

9. The method according to claim 8, characterized in that the introduction of the hot air can be adjusted in such a way that flat areas requiring intensive cleaning are scanned or are successively exposed to hot air piece by piece in a grid.

10. The method according to any one of the preceding claims, characterized in that the targeted application of hot air to cleaning-intensive areas takes place essentially with a directional component from top to bottom, in particular completely.

1 1. Oven, in particular for carrying out the method according to one of the preceding claims, with a muffle and with at least one fan and a heating device for a pyrolysis operation, the oven having special or additional nozzles for targeted action on cleaning-intensive areas of the muffle such as the underside , at the bottom of the corners, edges and inside of an oven door for better pyrolytic cleaning.

Oven according to claim 1 1, characterized in that the nozzles are firmly aligned.

13. Oven according to claim 1 1, characterized in that the nozzles are at least partially adjustable in their direction.

14. Oven according to claim 13, characterized in that the direction of the nozzles can be adjusted by controllable drive means.

15. Oven according to one of claims 1 1 to 14, characterized in that several nozzles are supplied with air together by a single fan.