GB2270378A - Self-cleaning oven - Google Patents

Abstract

In a cooking mode of an electric or gas oven a fan 4 directs air onto controls 5 for operating the oven and in a self-cleaning pyrolytic mode directs air into the oven cavity through an opening 7 in the direction of dotted arrow B, as a flap 6 is raised by a thermoactuator 8. The flap is raised when a predetermined temperature is reached in the oven so that a cool region of ineffective cleaning around the opening is avoided, and even oven temperature is made possible by turbulent flow in the oven. <IMAGE>

Description

SELF-CLEANING OVEN This invention relates to self-cleaning ovens, and especially to pyrolytic self-cleaning ovens i.e ovens in which the temperature is raised above normal cooking levels to perform a cleaning operation.

So-called continuous clean ovens are known in which cooking deposits on the oven walls are slowly destroyed at normal cooking temperature e.g. during normal cooking operations. In a typical pyrolytic self-cleaning oven, the temperature within the oven cavity is raised to a much higher level than for normal cooking e.g. of the order of 4000C for cleaning purposes. Deposits on the oven surfaces are wholly or partially oxidised and some are exhausted from the oven. The remainder ends up as a whitish powder, rather than the greasy layer which existed before the cleaning operation, and the whitish powder can be wiped clear with a damp cloth.

To assist in the combustion of cooking soil during the cleaning operation, it is usual to provide a short break in the door seal e.g. a plate may be provided to hold flat a short section of the door seal, and the corresponding part of the door may be chamfered, conventionally over the bottom section of the door seal.

However, a disadvantage with this is that the inlet air will be more or less at an ambient temperature, and so will create a colder region around the break which will result in locally poor cleaning performance.

The invention provides a pyrolytic self-cleaning oven, comprising a fan outside the oven cavity capable of directing an air flow onto controls for the oven in a cooking mode, and a flap movable to uncover an opening in the oven cavity to deflect air flow into the oven cavity in a pyrolytic self-cleaning mode.

In the pyrolytic self-cleaning mode, the air flowing into the oven cavity is heated by contact with the appliance, and thus prevents a cool region developing around the air inlet, and the assistance of the fan agitates the air in the oven cavity during the self-cleaning process, ensuring a more even temperature distribution throughout the oven.

The controls which the fan cools may be for performing temperature control of the oven or for controlling other functions, and may be electronic or electromechanical in nature, and they may be located above the oven cavity.

Equally, the air flow may extend through an opening at the front of the oven, and the air flow may be responsible for cooling manual controls on the outside of the oven. The fan may be located above the oven cavity and may draw air in at the rear and base of the oven. The flap may be arranged to be raised only when the oven temperature reaches a predetermined value, so that the air flow from the fan will at this stage be warm because of the temperature of the oven, in order to avoid having a cool region around the air inlet.

A thermoactuator may be provided to lower and raise the flap.

A pyrolytic self-cleaning oven constructed in accordance with the invention will now be described by way of example with reference to the accompanying drawing which is a schematic side view, partly in section, of the oven.

The oven is a built-in electric oven housed in a cabinet 1 having a bottom hinged door 2. Oven lagging 3 is provided in the other walls of the oven cavity. A fan 4 (tangential or radial) is mounted on an internal wall of the cabinet and directs air in the direction of the solid line arrow A. This airstream passes over controls which are electronic/electromechanical and are provided for sensing temperatures and controlling other oven functions e.g.

control 9 and other controls which are not shown. In addition, the airstream A emerges from the front of the appliance and serves to provide some cooling for manual controls such as 5 for controlling operations of the oven.

The fan 4 is set into operation as soon as the oven is operated in a normal cooking mode.

In accordance with the invention, a flap 6 is provided covering an opening 7 in the roof of the oven cavity, the flap being raised and lowered by a thermoactuator 8. When the flap is raised (dotted position) some of the air from the fan 4 now passes into the oven along the dotted line B instead of passing along the path A.

To perform a self-cleaning operation, the controls 5 are set to the appropriate position, and heat is applied in the oven cavity. When the temperature in the oven cavity as measured by a sensor (not shown) in the rear panel of oven reaches around 4000C, or optionally around 4500C, electronic signals from control box 9 cause a heating coil in thermoactuator 8 to be energised, which causes a wax bead in the thermoactuator to expand, thereby raising the flap 6.

The expansion is against the action of a spring so that, when the heating element ceases to be powered and the bead cools, the flap 6 returns to its solid line position.

In the dotted line position of the flap, the airflow from the fan is directed into the oven cavity through opening 7. The fan 4 draws its intake from the region above the oven cavity in which it is housed, this region being open at the rear. Accordingly, it draws in heated air from below and behind the appliance (arrows C), which rises around the heated oven. Because the air is heated it does not cause a cool region around the mouth of the opening 7, and also the air flow serves to make the air in the oven turbulent, thereby improving mixing. The elevated temperature together with the incoming air serves to oxidise the grease deposits to be cleaned on the walls of the oven, some of which are exhausted as smoke and some of which eventually oxidise to a white power which can be removed later with a damp cloth when the oven has cooled. The smoke passes along a flue (not shown) having a catalyst in it, into the kitchen.

At the end of the self-cleaning process, which may be terminated after a predetermined length of time, the heating element in the thermoactuator 8 is de-energised, the wax bead cools and the flap 6 closes, so that the oven is again ready for use in a normal cooking mode.

Of course, various modifications may be made without departing from the scope of the invention. Thus, instead of thermoactuator 8, other means may be provided for lifting and lowering the flap e.g. solenoids or motors. Also, while the oven is described as being an electric oven, the invention is also applicable to gas ovens.

Claims (6)

1. A pyrolytic self-cleaning oven comprising a fan outside the oven cavity capable of directing an air flow onto controls for the oven in a cooking mode, and a flap movable to uncover an opening in the oven cavity to deflect air flow into the oven cavity in a pyrolytic self-cleaning mode.

2. An oven as claimed in claim 1, in which the flap is raised in use.

3. An oven as claimed in claim 2, in which the a thermoactuator is provided for raising the flap.

4. An oven as claimed in claim 3, in which a heating element of the thermoactuator is controlled in response to a sensor for sensing oven temperature.

5. An oven as claimed in any one of claims 1 to 4, in which the fan is located above the oven cavity.

6. An pyrolytic self-cleaning oven as herein described with reference to the accompanying drawings.