Self-cleaning with pyrolysis
Siemens Elektrogeräte GmbH obtained a patent on May 30, 1973 for an "Electric cooking oven with pyrolytic self-cleaning" invented by Josef Ackermann.[1] A comparable technology had existed in the U.S. for around ten years, with General Electric selling self-cleaning ovens that operated according to the principle of pyrolysis from 1963. However, the innovation was introduced in Germany by Siemens and Neff at the beginning of the 1970s.[2]
The chemical process of pyrolysis has been known to people ever since the Stone Age. The process refers to the thermo-chemical breakdown of organic compounds at high temperatures without the addition of oxygen. Pyrolysis is used, for example, to extract tar from wood. The substances carbonize fully at very high temperatures, in other words, turn into carbon dust. This process can also be used for self-cleaning of ovens. The engineers at the cooker factory in Traunreut developed an oven for this purpose that could heat up to more than 500 degrees Celsius.[3] The oven needed a few hours for this cleaning process. "The automatic operating principle of the pyrolytic self-cleaning is based on three stages: The oven is first heated to 290°C for an hour (to dry out the food waste), the temperature is then increased to 500°C and residues burned for two hours with the large-surface grill acting as an afterburner, and, thirdly, the temperature is reduced.[4] In the meantime, the oven is heated to 465°C and, after two hours, then cooled for an hour. All contaminants are carbonized as the oven is heated, in other words, turned into ashes that can be removed with ease from the cooker. This dispenses with the need for complicated mechanical cleaning of those hard-to-reach areas in the oven and for users to resort to aggressive cleaning agents.
Der größte Nachteil der Selbstreinigung ist der hohe Energieverbrauch. Ständige Weiterentwicklungen wie doppelte Türdichtungen, reflektierende Innenscheiben, Türen mit vier Scheiben und eine neue Elektroniksteuerung und eine Reduzierung der Pyrolysetemperatur auf 465°C senken den Energieverbrauch.
Einzelnachweise
- ↑ The German Patent and Trade Mark Office (Deutsches Patent- und Markenamt; abbreviation: DPMA), Document DE000002166227A "Back- und Bratofen mit einer Einrichtung zur pyrolytischen Selbstreinigung", Owner Siemens Electrogeräte GmbH, registered on 9.03.1971, published on 30.05.1973. https://depatisnet.dpma.de/DepatisNet/depatisnet?action=bibdat&docid=DE000002166227A (last downloaded on 17.11.2016)
- ↑ BSH Corporate Archives, A05-0023, inform May 2000, Jg. 23, page 27. BSH Corporate Archives, A05-0030, inform 03/2007, Jg. 30, page 19.
- ↑ BSH Corporate Archives, A05-0022, inform 03/1999, Jg. 22, page 14.
- ↑ Press release from 1977 on how pyrolytic self-cleaning works, Bosch Archive, 770124.
- ↑ Die BSH wird 1967 als Bosch-Siemens Hausgeräte GmbH gegründet - abgekürzt BSHG. 1998 wird der Name in BSH Bosch und Siemens Hausgeräte GmbH geändert, die neue Abkürzung lautet BSH. Seit dem Verkauf der Siemens-Anteile der BSH an die Robert Bosch GmbH heißt das Unternehmen BSH Hausgeräte GmbH und wird weiterhin mit BSH abgekürzt.
- ↑ http://www.bosch-home.com/de/produktliste/kochen-backen/herde-backoefen/kompaktbackoefen (aufgerufen am 07.08.2017)