Air filter assembly e.g. high efficiency particulate air (HEPA) filter assembly for hand-held electric motor driven vacuum cleaner in household, has housing with scale formation for determining weight of air filter located in housing

摘要

The air filter assembly (L) has a housing (2) and an air filter (4) that is removably arranged in the housing. A scale formation is provided in the housing for determining the weight of the air filter located in the housing. The initial weight value is determined before flow of air through the air filter. A message is generated when the predetermined weight value is exceeded. The weight measurement is performed in regular time sequence. The weight measurement is performed in response to activation or deactivation of shiftable motor-driven fan. An independent claim is included for a method for measuring stress level of housing.