| 摘要 |
<p>#CMT# #/CMT# A gas pipe with variable-pressure flow and acoustic attenuation over a wide frequency band (F) in the form of tuned acoustic attenuators around and along the pipe, comprising (a) an absorption silencer or broad-band resonator (5; 5') of the multi-orifice type (6) for the low end of the band (F) and (b) at least four quarter-wave resonators (1-4; 1'-4') dimensioned to increase attenuation around their tuned frequency, preferably at the high end of the band (F). #CMT#USE : #/CMT# As an air inlet pipe for car engines (claimed). #CMT#ADVANTAGE : #/CMT# Quarter-wave resonators for the frequency range in question (1500-3300 Hz) need to be about 57 mm long, which is not always possible in the space under an engine hood. The invention overcomes this problem and provides significant acoustic attenuation (minimum requirement = 20 dB over the above range). #CMT#DESCRIPTION OF DRAWINGS : #/CMT# Perspective view (exploded) of gas pipe according to the invention. 1-4 : quarter-wave resonators 5 : broad-band resonator 6 : multiple orifices A, B : half-shells forming the pipe C, D : ends of pipe. #CMT#MECHANICAL ENGINEERING : #/CMT# Preferred System: The pipe comprises two half-shells (A, B; A', B') (preferably injection moulded and then assembled, e.g. by vibration welding) in which the forms of the attenuators (1-5; 1'-5') are created, the whole forming a gastight pipe. There may be (a) three quarter-wave resonators (1-3) in the plane of the silencer (5) and at least one other quarter-wave resonator (4) situated at the flow outlet in another plane, especially a plane at right angles to that of the other three (1-3), or (b) two quarter-wave resonators (1', 2') in the plane of the silencer (5') and two others (3', 4') in another plane, especially a plane at right angles to that of the first two (1', 2'), and with a partition between them.</p> |
