Miele has won the year-long legal battle over the invention of a very special washing machine drum. The patentability of the invention, registered for Miele as EP 0 935 687 B1, against which other German manufacturers had given notice of opposition, has been confirmed at the highest level by the board of appeal of the European Patent Office. According to this verdict, the Miele patent will remain in force and no other manufacturer may build washing machines with the patented Miele honeycomb drum before 2017.
The patent, registered as early as 1996 in Germany and a year later in Europe, allows only Miele to manufacture a drum with a sculptured honeycomb surface. A special production method, which is also patented, is used in the manufacture of the new honeycomb drum. The drum perforations to facilitate suds circulation are located at the points where three hexagons meet. There are approx. 700 holes in the new Miele honeycomb drum compared with around 4000 in the previous drum. With a diameter of 2 mm, the holes are also smaller than before when they had a diameter of 2.3 mm.
The new surface structure of the drum and the reduced surface covered by perforations means gentle laundry protection during washing and spinning. On account of the sculptured drum surface and the reduced number of holes, water is not released from the inner drum as quickly, resulting in more water being pushed ahead of the lifter bars as the drum turns. This results in the creation of a film of water between the laundry load and the body of the drum, cushioning textiles against the drum. This reduces the mechanical action on textiles in both the wash and spin cycles and results in demonstrably less fabric strength loss in the Miele honeycomb drum compared to its predecessors.
This gentle laundry care is confirmed in the WL 2019/00 report from 2000 compiled by Germany’s independent Krefeld Laundry Care institute (WfK), which says: ‘After 15 wash cycles using pre-washed standard cottons fabric swatches, Miele’s honeycomb system shows clear benefits over comparable machines. There was no pimply structure apparent on the laundry after a programme which included a spin cycle in the Miele honeycomb drum. Laundry lay in a loose heap in the drum.’ The report further confirms that even at a breakneck 1800 rpm, no impressions are left by the drum holes on fabrics and there is certainly no laddering. After spinning, laundry falls loosely from the drum walls – without any impressions being left by laundry plastered against the drum and forced through holes. Pimples on laundry after spinning is a common occurrence in drums with larger perforations as a result of centrifugal force.
As early as 2003, the ‘Stahl-Informations-Zentrum’ (Steel Information Centre) in D¼sseldorf awarded its steel innovation prize to the Miele honeycomb drum. According to the jury, ‘The domestic appliance manufacturer Miele & Cie. KG uses the excellent ductile properties of stainless steel to produce a new sculptured honeycomb surface. During production, a special new method is used which creates a honeycomb surface with new properties. This honeycomb drum, in which the number and size of holes have been greatly reduced and their arrangement modified, guarantees gentle laundry protection during both washing and spin cycles ““ even at high speeds.’
From Miele
