| 摘要 |
<p>PCT No. PCT/AU81/00043 Sec. 371 Date Dec. 22, 1981 Sec. 102(e) Date Dec. 22, 1981 PCT Filed Apr. 10, 1981 PCT Pub. No. WO81/03081 PCT Pub. Date Oct. 29, 1981.An impulse noise generator having means to store a volume of compressed gas and suddenly to release same to eject through a nozzle (14) comprising a body (4) having a hollow stepped piston (1) arranged to move forward by gas pressure admitted through an inlet (9) when a spring-loaded valve (15) is closed and including a pressure chamber (7) to which gas is admitted through the valve (15) when the piston (1) is at the forward and of its stroke, and gas release means to cause the piston (1) to move back rapidly to exhaust the gas from the chamber (7) to the nozzle (14).</p> |
