175 The characteristic of aerosol emission from motors

A motor plays a crucial role in household appliances, such as fans, hair driers, cleaning robots and electric shavers. However, varies studies have showed that the motors inside the household appliances, such as vacuum cleaners and toy cars, generate the ultrafine particle, which have been proven to be harmful to human health. So, we will test the particle number concentration and particle size, and know about the main mechanisms by which motors generate particles. Ultimately, find an effective way to control motor-generated particles We establish an experimental chamber with a volume of 2 liters. Test motor would be placed inside the chamber, and the chamber were supplied with particle free air to bring out the particles. We use a Condensation Particle Counter and a Scanning Mobility Particle Sizer to monitor the particulate concentration and particle size range over time. A brushed DC motor and a brushless DC motor with a rated output power of 64 W commonly used indoors, will be utilized for testing. The results of mechanism experience indicate that both the brushes and the bearings generate particles through mechanical friction, and the particles generated through spark discharge are 100 times more numerous than those generated through mechanical friction. This suggests that spark discharge is the main mechanism for particle generation by the motor. At a rotational speed of approximately 10,000 RPM, the particle emission rate reaches as high as 3.4 x 107 #/sec.However, at 10,000 RPM, the particle emission rate of the brushless DC motor is only 2.2 x104 #/sec, about one-thousandth that of the brushed DC motor.