Vacuum pump exhaust muffler
AssigneeAllied Chemical Corporation
InventorsWilliam R. Weiss, Lee E. Remy
Life of this patent
Estimating the term…
Abstract
A muffler for use in conjunction with a high intensity, low frequency noise-propagating open pipeline is disclosed. The muffler features an acoustically lined expansion chamber in tandem with a reasonator chamber. The length of the expansion chamber is approximately 25 percent of the wavelength to be attenuated. An exit tube, which passes through the resonator chamber to lead from the expansion chamber to the muffler outlet, is partially perforated with the perforations being restricted to at most the 50 percent of the exit tube closer to the muffler outlet. Audible noise which is emitted by the open pipeline is reduced by up to 30 dB and 11 .DELTA. dB(A) and brought to within acceptable levels.
Claims10
A muffler comprising:
- (a) a housing;
- (b) an inlet to said housing;
- (c) an outlet from said housing;
- (d) an elongated exit tube communicating with said outlet and extending within said housing;
- and
- (e) a partition being located in the annulus between the inner wall of said housing and the outer wall of said exit tube, the inlet end of said exit tube terminating at and substantially in register with the opening in said partition, said partition forming with said housing an expansion chamber which includes said inlet, said partition forming with said housing a resonator chamber occupying the annular volume surrounding said exit tube, the cross-sectional area of said expansion chamber in a plane substantially parallel to the plane normal to the axis of said inlet being greater than the cross-sectional area of said plane of said inlet, the length of said expansion chamber from said inlet to said partition being approximately 25 percent of the wavelength to be attenuated, the inner wall of said housing which forms said expansion chamber being at least partially lined with sound absorbing material, said exit tube being partially perforated with the perforations being restricted to at most the 50 percent of the length of said exit tube within said housing closer to said outlet.
A muffler, for use in conjunction with a vacuum pump exhaust pipe, comprising:
- a. a generally cylindrical housing;
- b. an inlet to said housing which is connectable to a vacuum pump exhaust pipe;
- c. an outlet from said housing;
- d. an elongated exit tube communicating with said outlet and extending within said housing, said exit tube being coaxially aligned with said inlet, said exit tube having a plurality of perforations which are restricted to the 25 percent or less of the length of said exit tube within said housing closer to said outlet to create a total open area for said exit tube of from about 0.8 to about 13.0 percent;
- and
- e. a partition being located in the annulus between the inner wall of said housing and the outer wall of said exit tube, the inlet end of said exit tube terminating at and in register with the opening in said partition, said partition forming with said housing an expansion chamber which includes said inlet, the cross-sectional area of said expansion chamber in a plane substantially parallel to the plane normal to the axis of said inlet being greater than the cross-sectional area of said plane of said inlet, the distance from said inlet to said partition in said expansion chamber being approximately 25 percent of the wavelength to be attenuated, the curved portion of said inner wall of said housing which forms a part of said expansion chamber being lined with sound absorbing material, said partition forming with said housing a resonator chamber occupying the annular volume surrounding said exit tube, the ratio of the volume in cubic inches of said resonator chamber to the distance in inches from said inlet to said partition in said expansion chamber being from about 27 to 1 up to 110 to 1.
Dependencies are inferred from the claim text.