| 摘要 |
An automotive exhaust system has a particle filter with a permeability measuring assembly consisting of a sound source (1) which emits an ultrasonic signal (1.1) through the particle filter (3). The modified (1.2) sound is detected at another point in the filter by a sound detector (3) and the difference between the two (1.1, 1.2) is assessed by a signal processing unit (4). The ultrasonic noise emitter (1) may be a motor, a whistle or a loudspeaker and is detected by a microphone (2), both (1, 2) of which are located on one or two sides of the particle filter. The signal processing unit compares the amplitude of the incoming sinusoidal or impulse signal with the outgoing signal and uses the difference to determine the condition and serviceability of the filter. Also claimed is a commensurate operating process.
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