US2485392A

US2485392A - Silencer with cloth gas-conducting conduit

Info

Publication number: US2485392A
Application number: US568035A
Authority: US
Inventors: Ralph L Leadbetter
Original assignee: Burgess-Manning Co
Current assignee: Burgess-Manning Co
Priority date: 1944-12-13
Filing date: 1944-12-13
Publication date: 1949-10-18
Anticipated expiration: 1966-10-18

Description

Get. 18, 1949. R. L.. LEADBETTER 2,485,392

SILENCER WITH CLOTH CTAS CNDUG'I'INGIA CONDUIT Filed Dec. 1s, 1944 l 2 sheets-sheet 1 Oct, 18, 1949.

LEADBETTER SILENCER WITH CLOTH GAS-CONDUCTING CONDUIT 2 Sheets-Sheet 2 Filed Dec. 13, 1944 INVENTOR. xO/Eooag @er Patented Oct. 18, 1949 SILENCER WITH CLOTH GAS-CONDUCTING CONDUIT Ralph L. Leadbetter, Roselle, Ill., assignor to Burgess-Manning Company, Chicago, Ill., a corporation of Illinois Application December 13, 1944, Serial No. 568,035

9 Claims.

This invention relates to muiliers or silencers for smoothing the flow of pulsating gases to thereby prevent noise which would otherwise result.

The object of the invention is to provide an extremely simple, yet effective, device for quieting such potential sources of noise as the intakes of internal combustion engines, intakes and discharges of air compressors, and the like.

In carrying out the invention the pulsating gases are conducted through a tube or channel whose Walls are pervious to gases and includes a fabric layer, as hereinafter more fully described, whose impedance to the flow of gases through the material is such that the noise-provoking pressure fluctuations are effectively damped. In

certain embodiments of the invention, the influence of the pores of the fabric in smoothing the ow of gases in the main conducting channel is supplemented by limited sympathetic dilation and contraction of the tube or channel itself.

Fig. 1 is a longitudinal sectional view of a silencer embodying the invention;

Fig. 2 is a longitudinal sectional View of a silencer embodying a different form of the invention; and

Fig. 3 is a longitudinal sectional view of a silencer illustrating another modified form of the invention.

Fig. 4 is a fragmentary view enlarged of a portion of the silencer of Fig. 2.

The simplest form of the invention is illustrated in Fig. l. This silencer consists essentially of casing l including end flanges 2, inlet and outlet snouts 3 and 4, respectively, for connecting the silencer into the line carrying the flowing gases, and a fabric tube 5 extending throughout the length of the device between the inlet and outlet snouts. The ends of this fabric tube are clamped around the internal ends of the snout members by suitable means, such as steel tapes 6.

The diameter of casing l is preferably from two to three times that of tube 5, thus providing a space 'l of considerable volume in which the gases may expand or contract depending upon the flow through the fabric of tube 5 from or into the main conducting channel formed by the fabric tube.

In making tube 5, any suitable fabric produced from fibrous material and which is pervious to the iicw of air therethrough may be used. As used herein, the term textile fabric means and is limited to cloth or other material that is woven or knit from Vegetable, animal, or organic or inorganic synthetic fibers. Examples of suitable materials include ducl, burlap, and cloth woven from asbestos, glass, plastic, or other kinds of ber. Solid sheet materials rendered pervious by perforation are not satisfactory and are not included as a permissible variant herein. A single layer of fabric is suflicient. For some applications it is desirable to employ a double layer for strength but the eilciency of the silencer is not necessarily thereby improved. Also, since the operation of the device depends upon the impedance of a single layer of the fabric as a multiple throttling valve, the device is in no way dependent upon the absorption of sound energy by means of a sound absorbing body and materials generally and properly so classified are not used in the silencing units of the invention herein described and claimed. In other words, the fabric employed in the silencer is pervious to, rather than absorptive of, sound.

The silencer of this invention may be employed in the quieting of gases pulsating in a conduit from a wide range of sources. The particular fabric to be used in any instance will depend upon the severity of the pressure fluctuations and the temperature of the gases since the material must be strong enough to resist rupture and must not disintegrate when exposed to the temperature of the gases. For convenience, the conditions existent within the intake line of an internal combustion engine may be used to illustrate the operation of the silencer. The sucking of the air into the engine cylinder as the intake valve opens results in a partia1 vacuum in the conduit at the valve end and inward flow of the gases. When the intake valve is again closed, the momentum of the moving gases in the conduit causes the building up of a substantial pressure at the valve which propagates as a pressure wave front outwardly Within the conduit. The timed recurrence of this cycle results in more or less violent pulsating flow of the air, the amplitude of the pulsations depending upon many factors not here described.

Propagation of the pressure wave within the intake line without substantial loss of amplitude results from the rigid confinement by the walls of the pipe or conduit. The damping action of the silencer herein described appears to be attributable to the partial liberation of the gases from such rigid confinement provided by the fabric tube as a segment of the conduit. The pressure of the wave fronts is substantially dissipated as the gases flow through the pores or apertures of the fabric into the space "l, the direction of flow being reversed as the pressure front passes. The mpdance characteristics of the pervious fabric are such that effective smoothing of the flow of gases is obtained.

In addition to the materials listed above for use in the fabrication of tube 5, knitted fabrics may be employed. Fabrics of this type are laterally stretchable so that the tube walls them selves may dilate under the influence of the wave fronts permitting limited expansion of the gases Within the tube in addition to dissipation through its walls. Bias-cut woven fabrics function similarly but to a lesser extent. The action further serves to smooth the flow of gases.

A muling section of known construction is combined with a section embodying the invention in the silencer illustrated in Fig. 2. This unit is suitable for use as an intake silencer` for a Diesel engine. The interior of the unit within casing 8 and end anges 9 and I0 is divided by a partitioning flange I I into two silencing sections. The first section through which the air passes in flowing from the atmosphere to the engine comprises a perforated tube I2 extending through central openings in flanges 9 and II which tube is covered substantially throughout its length by burlap indicated at I3. Suitable means are provided at the inlet end of this tube for connection of the silencer with the intake piping. second section of the silencer of Fig. 2 consists principally of a chamber I4 formed by baffle member I5 through which perforated tubes I@ extend to conduct the gases to the zone adjacent the silencer outlet IT.

The rst section of this silencer differs from the device of Fig. l principally in that the fabric impedance member is supported by a perforated metal tube I2 whereas the corresponding member 5 of Fig. 1 is unsupported. Hardware cloth or screening or other apertured materials may be used for supporting the fabric layer I3. In the particular embodiment illustrated the burlap is spirally wound upon the supporting element. Other modes of application may be used.

As is well understood in the art, the purpose of employing two or more silencing sections having different structural arrangements and therefore different functional characteristics is to obtain efficient silencing action over a broad range of pulsation frequencies.

In Fig. 3 a modified form of the invention is combined with a silencing section similar to that of Fig. 1. This device may be employed as an intake silencer and is intended to be connected to the intake pipe at the inlet end thereof. Casing I8 and end flanges I9 and 2G form an enclosure which is divided into two sections by a partition flange 2 I. Intake end flange I9 is preferably formed to provide a gradually converging passageway for the gases as they enter the silencer. A perforated tube 22 extends inwardly from this flange toward a central opening in partition flange 2I, leaving a gap between the end of the tube and the partition for direct communication with the space 23. A fabric layer 24 encircles tube 22.

In the second section of this unit a perforated tube 25 extends from the central opening in partition 2I through a similar central opening in end flange 20. A partition 26 divides the space around tube 25 into two parts. A layer of fabric 2l is placed around one portion of tube 25 and a layer of fabric 28 covers the remaining portion. If desired, two or more partitions may be used to divide the space around tube 25 into three or more separate chambers.

As the description and illustrations herein indi cate, the effective performance of the invention is not conditioned upon critical structural material or dimensions. Any relatively thin pervious brous material, not limited to the examples herein given, may be used, and direct communication between the main conducting channel and the expansion space surrounding it is not necessarily harmful. Although particular materials are specified in the descriptions of the devices of Figs. 2 and 3, it will be understood that any of the porous fibrous fabrics or materials herein claimed as suitable may be used in these embodiments as well as that of Fig. l. It will be appreciated, however, that the advantageous effects of the pervious tube segment are increased with increased effective area of the material.

I claim:

1. A silencer for pulsating gas streams comprising an elongated casing forming a chamber having an inlet opening at one end and an outlet opening at the other end thereof and e. conduit having walls comprising a textile fabric pervious to air and sound extending from said inlet to said outlet opening and leaving a substantial space around said conduit within said chamber, said conduit forming a dilatable sleeve unconned except adjacent the ends thereof.

2. A silencer in accordance with claim 1 in which the conduit consists of a knitted sleeve.

3. A silencer in accordance with claim l in which the conduit consists of bias-cut woven fabric.

4. A silencer for pulsating gas streams comprising an elongated casing forming a chamber having an inlet opening at one end and an outlet opening at the other end thereof and a conduit having walls comprising a textile fabric pervious to air and sound extending from said inlet to said outlet opening and leaving a substantial space around said conduit within said chamber, said conduit forming a dilatable sleeve unconfined except adjacent the ends thereof.

5. A silencer for pulsating gas streams comprising an elongated casing forming a chamber having an inlet opening at one end and an outlet opening at the other end thereof and a conduit having walls comprising a single layer of a textile fabric pervious to air and sound extending from said inlet to said outlet opening and leaving a substantial space around said conduit within said chamber, said conduit forming a dilatable sleeve unconflned except adjacent the ends thereof.

6. In a silencer for pulsating gas streams, a silencing section comprising means forming a chamber having -an inlet and an outlet opening, a perforated tube of self-sustaining material extending between said inlet and outlet openings within said chamber, and a textile fabric pervious to air and sound substantially covering said perforated tube, said fabric forming a dilatable sleeve unconned except adjacent the ends thereof.

'7. In a silencer for pulsating gas streams, a silencing section comprising means forming a chamber having an inlet and an outlet opening, a perforated tube of self-sustaining material extending between said inlet and outlet openings within said chamber, and a single layer of a textile fabric pervious to air and sound substantially covering said perforated tube, said fabric forming a dilatable sleeve unconiined except adjacent the ends thereof.

8. In a silencer for pulsating gas streams, a silencing section comprising means forming a chamber having an inlet and an outlet opening, a

perforated tube of self-sustaining material extending between said inlet and outlet openings Within said chamber, and a strip of textile fabric pervious to air and sound spirally wound around said tube and substantially covering the same, said fabric forming a dilatable sleeve unconned except adjacent the ends thereof.

9. In a silencer for pulsating gas streams, a silencing section comprising means forming a chamber having an inlet and an outlet opening, a, perforated tube of self sustaining material extending into said chamber from said inlet opening toward said outlet opening but terminating short thereof, and a textile fabric pervious to air and sound substantially covering said tube, said fabric forming a, dilatable sleeve unconned eX- cept adjacent the ends thereof.

RALPH L. LEADBETTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,916,908 Stacey et al July 4, 1933 2,043,731 Bourne June 9, 1936 2,089,492 Lambert Aug. 10, 1937 2,271,892 Bourne Feb. 3, 1942 2,311,676 Maxim Feb. 23, 1943 2,326,612 Bourne Aug. 10, 1943