A HEATER UNIT FOR OVENS

Abstract: All components and installations for an oven for food preparation including controls are placed in the oven door. This means that the door can be connected by means of hinges and plugs to any door frame and any cavity. The cavity may be transparent so that the food may be inspected from any angle.

Description: otherhoc A heater unit for ovens The inventions concerns a heater unit for ovens for the preparation of food. Ovens for the preparation of food generally consist of a cavity and heating means. The traditional electrical oven has heating elements in conjunction with the walls of the cavity which is made of a heat resistant material, such as sheet metal. These heating means may be supplemented with radiating high temperature heating means, such as a grill. More recent oven constructions circulate the hot air, and in some cases all the energy is supplied as hot air which is generated in a heater unit external to the cavity but connected to it by an inlet and an exhaust . The hot air is re-circulated in the oven-heater unit system, and is reheated before injection. It has been considered a complex task to redesign an oven to a different volume, because the cavity has to be reconstructed with new inlet and outlet vents, and the utilization of space outside the cavity has to be redesigned. Furthermore the temperature measuring means have to be redesigned and placed differently. This makes the change of models more expensive which reflects in the cost to the consumer or end user. This situation is redressed by the invention which is particular in that all components, such as heating means, air circulating means, temperature control means, or adjustment means are disposed in the oven door. In this manner it becomes possible to have a completely free hand in designing the cavity which may be made any size smaller than the maximum that the door unit will supply. The use of the invention also means that the door unit may be manufactured in a high-technology manufacturing plant with all electrical installations and controls. Such units may be individually tested on test benches which take up much less space than traditional test benches. The manufacture of the oven itself may take place in a low-technology assembly plant where the door is a component connected by hinges and pluggable connections to the rest of the oven. An advantageous embodiment of the invention is particular in that the components comprise a steam generating unit. This means that the whole cooking and baking process may be controlled entirely from the oven door. A further advantageous embodiment is particular in that the cavity is free-standing and transparent. This enables the close supervision of the baking process, and there is no need to peer through the door window. In effect, the door may have no inspection function at all. The lights for the inside of the cavity may also be placed in the door, and a suitable stream of air may prevent condensation on the sides of the transparent cavity. A further advantageous embodiment comprises a radiating heating element in the door, the radiation of which is distributed over the food by means of an infrared reflector. This reflector may perform a scanning motion in order to reach all the food. The invention will be described in greater detail with reference to the drawing, in which Fig. 1 shows the principal components in an oven door according to the invention, and Fig. 2 shows an infrared scanning device. In Fig. 1 is shown a cavity 1 for an oven. Thiε cavity is quite thin and may be in a transparent material . The cavity is closed by means of an oven door which is hinged at 2. The oven door contains a heating unit consisting of a ventilator 3 rotated by a motor 4 which pulls air from air inlets 5 and 5' and heats it by means of a heating resistance 6. The air is expelled through the flow control grid 7. In order not to heat the outside of the oven door it is insulated as shown at 8. The temperature inside the oven is sensed by means of the temperature sensor 9, and the operation is controlled from a control panel 10 disposed at the top of the door above the handle 11. The control panel also comprises a control computer for controlling the operation of heater 6 and the velocity of air by controlling the motor 4. The internal wiring is not shown, however by means of plug 12 the door is connected to the oven chassis. This forms the only connection between the chassis and the oven door. The controls also comprise a safety device which disables the heating and ventilator when the door is opened. In Fig. 2 is shown a door which is similar to that shown in Fig. 1. The cavity is shown in broken lines 1. In order to provide radiant heat to the food, a halogen line source 13 is fitted inside a reflector 14. The radiation which is both visible light and infrared is directed towards a reflector 15, from which it is directed towards the food, essentially covering the horizontal plane 16 inside the cavity. The plane reflector 15 is a Fresnel-type reflector (cylindrical, i.e. with straight parallel prismatic reflectors) which is the only practical way to provide in a small space an uneven distribution of radiation in the directions a and b. A greater part of the radiation from the halogen line source is directed towards a and relatively less towards b. This is necessary to provide an even radiation density over the plane 16. A similar distribution may be obtained with a cylindrical curved reflector, however the space taken up by the reflector would be greater.

Claims: P A T E N T C L A I M S 1. A heater unit for ovens for the preparation of food c h a r a c t e r i z e d i n that all components, such as heating means, air circulating means, temperature control means, or adjustment means are disposed in the oven door. 2. A heater unit according to claim 1, c h a r a c t e r i z e d i n that the components comprise a steam generating unit. 3. A heater unit according to claim 1, c h a r a c t e r i z e d i n that the cavity is free-standing and transparent. 4. A heater according to claim 1, c h a r a c t e r i z e d i n that it comprises a radiating heating element in the door, the radiation of which is distributed over the food by means of an infrared reflector.

Inventors: ESKILDSEN CHRISTIAN, ESKILDSEN, CHRISTIAN
Applicants: ELECTROLUX AB, ESKILDSEN CHRISTIAN, AKTIEBOLAGET ELECTROLUX, ESKILDSEN, CHRISTIAN
Application year: 1997
Main classification: A21B1
IPC codes: F24C15