Abstract: The electric motor, especially a permanently excited direct current motor, has a housing (16) carrying a magnetic pole (15) and a grounding ring (17) made from magnetically conductive material and mounted on the housing. In order to reduce the noise generation of the motor the grounding ring (17) is a knit article made from a thread-form or wire-form magnetically conductive material.

Abstract: In known retaining devices for electric motors, rotationally flexible retaining elements on the order of leaf springs are provided between a receiving housing and the electric motor and serve to decouple noise of the electric motor. The novel retaining device for an electric motor includes retaining elements that extend axially between a receiving housing and the motor housing. These retaining elements enable low-frequency decoupling below the frequencies to be decoupled; on the occurrence of natural resonance when the electric motor is turned on and off or there are shocks from outside, the torsional motion of the retaining elements is limited by stop elements. The retaining device is especially well suited to electric motors of blowers.

Abstract: The muffler for a fan, especially a bypass air fan of an internal combustion engine, has a housing provided with an air outlet opening and an air inlet opening and including a housing pot having a top opening and a flat housing cover at least partially closing the top opening of the housing pot, the air inlet opening being coaxial to the housing axis and advantageously provided in the housing cover, and a damping insert made from a sound absorbing material and being provided with at least one helical or spiral air flow passage providing a connection between the air outlet opening and the air inlet opening so that air can flow through the air inlet opening to the air outlet opening. In one variation the air outlet opening can open radially from the housing pot and the air inlet opening can be provided centrally in a flat housing cover.

Abstract: A fan wheel has a cup shaped hub having an outer cup wall with a plurality of vanes and a cup bottom connectable with a shaft of a drive and provided at its inner side with a plurality of ribs defining a plurality of fields therebetween. The cup bottom in the region of the fields has a plurality of depressions extending from its inner side and having a width approximately 70% of a thickness of the cup bottom.