Noise reduction system

Claim 1

In combination with a draw point localizing jet wherein advancing yarn is subjected to pressurized, superheated fluid flow, and wherein said draw point localizing jet has at least one yarn passage passing therethrough and defining yarn entrance and exit ends thereof, said yarn passage having an adjacent access slot to facilitate string-up and having at least one fluid conduit per yarn passage for admitting treating fluid thereinto, the improvements comprising: A. an exhaust muffler, said muffler comprising: i. a boxlike metal housing, said housing being located at said exit end of said jet, one corner of said housing being hinged so as to provide a door which pivots to an open position for access to said jet during string-up and to a closed position for treatment during operation, said door being located on the side of said housing corresponding to the side of said jet having said access slot therein, said housing comprising two chambers separated by baffle means connected to and extending inward from the exit of said housing towards said exit end of said jet, said baffle means extending to a point just short of said jet exit so that a gap is left between said baffle means and said exit end of said jet, said gap providing a sight line for an operator, the first of said chambers substantially surrounding said exit end of said jet and surrounding said yarn to a point downstream thereof and with an opening for passage of yarn therethrough, the second of said chambers being positioned contiguous to said first chamber; ii. means for mounting said housing on said jet; iii. two metal sound absorbing inserts, said inserts comprising a metal frame, a metallic honeycomb sheet, a sintered metal sheet, a perforated metal sheet, and means for sandwiching these elements, the first of said inserts having a U-shape and being mounted opening towards said door in said first chamber, the second of said inserts having a shape corresponding to the interior portion of said door and being mounted thereon, said inserts being adapted for removable connection to said housing and said interior portion of said door so as to line said first chamber without blocking the passage of said yarn therethrough, said metal frame of said inserts being adjacent said housing and said perforated metal sheet being furthest away from said housing, said honeycomb sheet being adjacent said frame, said sintered metal sheet being adjacent said perforated metal sheet, the cells of said honeycomb sheet opening in a plane transverse to that of said yarn passage if extended through said first chamber, the distance between said sintered metal sheet and said metal frame which is occupied by said honeycomb sheet being approximately 0.25 sound wavelength which corresponds to sound frequencies of 8,000 and 16,000 cycles per second, the open area of said perforated metal sheet ranging from 30 to 45%; iv. means for mounting said inserts to said walls defining said first chamber and to said interior of said door, and B. access slot silencing means, said access slot silencing means comprising a projection of said housing, a mounting plate, a silencing plate, a pin, and a compression spring, said projection being an extension of said housing door in the direction of said jet entrance, said projection pivoting with said door into an open and a closed position, said projection blocking access to said side of said jet having said access slot therein when in said closed position, said projection having said mounting plate spaced therefrom and attached thereto on the side closer to said jet when in said closed position, said mounting plate having a slot with said pin passing therethrough, said pin being connected on the end located closer to said jet to said silencing plate and being connected at its other end to stopping means which prohibits its passing completely through said slot, said compression spring surrounding the portion of said pin located between said projection and said slot, said silencing plate corresponding in length and being slightly wider than said access slot in said jet; whereby the noise level of said jet is changed from a continuous source to an intermittent source, emitting high level noise only during string-up and alignment, by: (1) the automatic closure of said access slot by said silencing plate when said jet is operational and said projection is pivoted along with said housing door to within 1.5 inches of said access slot, said closure resulting from the vacuum-like action induced by said treating fluid; and (2) the closure of said access slot simultaneously closing said housing door to close said first chamber of said exhaust muffler thereby reducing noise at the yarn exit, and whereby the noise level of said jet is reduced by up to 16 ± 1.5 Δ dB(A) when said housing door and said projection are in said closed position.