US2290818A - Silencer - Google Patents

Description

Patented July 21, 1942 SILENCER John P. Tyskewicz, Hartford, Conn., assignor to The Maxim Silencer Company, Hartford, Conn, a corporation of Connecticut Application November 7, 1940, Serial No. 364,695

14 Claims.

This invention relates to silencers for use with internal combustion exhausts and intakes, air compressor intakes and discharges, and other installations. It has particular utility when both noise and a pulsating gas flow are present.

It has hitherto been proposed to constructing effects, they have presented difiiculties in the production of so-called shell noise, due to the shock-excitation of vibrations in the walls of the silencer, and have in some cases offered without apparent cause a relatively high back-pressure to the engine exhaust.

I have found that greatly improved results will be obtained in silencing effect, reduction of shell noises, and diminution of back pressure, by a rearrangement of the disposition of the pipes within the chamber. In prior practice each pipe has extended into the chamber from about half-way up to a point fairly close to that end of the chamber opposite that from which the pipe entered. In accordance with the present invention at least one of the pipes is retroverted or recurved so that it terminates close to th end of the chamber through which it entered. The pipe, which is provided with lateral escap openings distributed throughout its length, gives the gas Pulses a greater chance to bleed off through these openings than the much shorter tubes previous'ly used. This improves the silencing effect and reduces the tendency to produce shell noise. The added length of tube which is provided with lateral openings also greatly reduces the tendency of the exhaust line to resonate at particular frequencies and makes the positioning of the silencer in the exhaust line non-critical. These improvement are apparently accentuated, without increasing back-pressure, by the curved path which the gas must take in passing through the pipe.

by the discharge or the gas through the open end of the pipe at a point at a distance from the entrance wall substantially on the order of the diameter of th pipe, a distance equa1 to sixiifths of the pipe diameter appearing to give optimum results. The entering gas thu has no opportunity to exert by its flow past the outlet Th back pressure of the device is kept down flow, as has been the case in some prior constructions.

In many cases it will be sufficient to have one pipe only within a chamber, th chamber leading into an exhaust pipe or a second chamber through one or more perforations in its walls. This permits a longer length of pipe within the chamber than if room had to be found for two recurved pipes, which, due to practical limitations on the diameter of the chamber and the necessity of preserving a volume for expansion outside the pipes, can in general not be arranged side by side.

The invention will now be described With reference to the various embodiments shown in the accompanying drawings, in which:

Fig. 1 is a median section through a twochamber cylindrical silencer constructed in accordance with one form of the invention;

Figs. 2, 3, and 4 are similar views showing modifications;

Fig. 5 is a median section through one form of single chamber silencer;

Fig. 6 is a median section through a modified form of two-chamber silencer;

Fig. '7 is a section on line 1-1 of Fig. 6;

Fig. 8 is a median section through a twochamber silencer intended particularly for use where it is necessary to cool the exhaust gases by the injection of water;

Fig. 9 is a median section through a twochamber silencer constructed in accordance with the invention but utilizing different mechanical features which have certain advantages in the building of the silencer;

Fig. 10 is a section on line l0 l0 of Fig. 9;

Fig. 11 is a single-chamber silencer constructed in accordance with the mechanical principle of Fig. 12 is a section on line l2--I2 of Fig. 11;

Fig. 13 is a fragmentary view showing an alternative Way of forming the open end of the conducting tube;

Fig. 14 is a fragmentary median section showing a single-chamber silencer in which both inlet and exhaust pipes enter from the sam end; and

Fig. 15 is a diagrammatic view of a threesection silencer.

The silencer shown in Fig. 1 has a casing IS with end headers I1 and II. This casing is preferably made cylindrical for ease in manufacture. Through the header ll enters a pipe l8 which is retroverted or recurved upon itself as at l9, and which has an open end 20 positioned a distance tube a suction action tending to prevent outfrom the header I! on the order of the diameter of the tube. Preferably the spacing between the open end and the header is made six-fifths of the diameter as this has been found to produce a minimum back pressure. The tube has arranged along its length a plurality of lateral escape Openings in the form or perforations 2| or slots such as ar shown in some-of the other modifications. The casing is divided by a partition 22, thus forming a chamber 23 into which the pipe I8 extends and a chamber 24 into which a pipe 25 extends. The partition is provided with a central perforation 26 preferably guarded by a baffle 21 held on posts 28 to cause dispersion of any slugs of gas that might otherwise tend to pass through the central opening, The pipe 25 extends through the partition l1 and. is recurved upon itself and provided with lateral openings similarly to the pipe I8. The partition 22 should be located so that the two chambers 23 and 24 are of unequal lengths, preferably having a non-integral relation with respect to each other as it has been found that this proportioning of the chambers avoids the tendency to pass through the device certain frequencies forming normal modes of vibration of th gas longitudinally of the chamber. The operation of this device has been discussed above and need not be repeated.

Fig. 2 shows a somewhat similar device in which similar parts have been denoted by the same reference characters. The difference between this device and that shown in Fig. 1 is that the partition 22 has been replaced by a partition 38 through which a tube 3| passes, the tube having recurved ends 32 and 33 located within the chambers 23 and 24 respectively. The open ends of this tube 3| are directed towards the partition 36 and are spaced from it a distance preferably on the order of the diameter of the tube. This tube, as well as the others, is

provided with lateral escape openings 34,

Fig. 3 shows a similar structure except that the tube 3| is replaced by a tube 35 having its open ends 36 directed toward the cylindrical wall of the container rather than toward the partition 30. This construction has somewhat higher back pressure than the device of Fig. 2 but is easier to construct. The partition 36 has in this case been shifted slightly to indicate that its position is not critical but in general it will be found desirable to have greater dissimilarity between the lengths of the two chambers than is shown in Fig. 3.

Fig. 4-. illustrates a further form of the device in which one end connection 40 to the interior of the casing 4| enters directly into one of the two chambers 42 into which the casing is divided by a partition 43-. In this case a tube 44 extends into the chamber 42 through the partition 43 and has an open end 45 and lateral escape openings 46 arranged as previously described. A second tube 41 enters the second chamber 48 and is likewise provided with escape openings 49 and an open end 50.

Fig. shows a modification illustrating both a different type of" lateral escape opening and the adaptation of the silencer to a single chamber device. In this case one pipe 5| enters the chamber 52 at one end while a second pipe 53 enters the chamber at the other end and is recurved upon itself as at 54, terminating with an open end 55 spaced from the header 56 a distance on the order of the diameter of the .pipe. In this form the escape openings have been shown as composed of slots 51 formed in the straight parts of the tube and holes 58 'formed in the curved parts. The acoustical performance of the two types of openings are the same,

the chance for the gas to escape laterally from and into the pipe being distributed with practical uniformity along it length; but a slot is somewhat easier to machine in a straight tube than is a series of holes, the converse being true in curved portions.

Figs. 6 and 7 show a device having two chambers 66 and BI, into the former of which extends a recurved pipe 62 provided with an open end and lateral escape openings as before. The chambers are separated by a central partition 63 from which an off-center pipe 64 extends into the chamber 60. This chamber has an open end extending toward the center of the chamber 60 and has lateral escape openings 65 in its walls. While not as eflicient as some of the other forms described, this type of construction presents some constructural activities even to the point where the tube 62 could be extended sufficiently to overlap the tube 64 partially without too much decrease in the free volume within the chamber 60. The recurved pipe 66 within the chamber 6| is in this case constructed as previously described.

In Fig. 8 I have shown in median section a silencer intended for use generally on shipboard where it is desirable to flood the silencer with water in order to cool the gases and extinguish any sparks. The casing 10 is in this case divided into chambers H and 12 by a partition 13 which, as in other cases, is preferably disposed off-center of the length of the casing. An inlet pipe l4 enters the chamber ll and is recurved upon itself at 75, being provided with lateral escape openings '16 and an open end 11. In addi tion the two limbs of the curved pipe are preferably connected by short pipes 18 having lateral escape openings 79. These pipes not only permit even better evening out of the gas pulses :but add materially to the strength of the device. The partition 13 is pierced by a short tube having a lateral escape opening 8| extending substantially throughout its length and is also pierced by a hole 82 provided for drainage at the bottom of the partition. The exhaust pipe 83 extends into the casing tangent to its bottom and has within the casing a lateral escape opening 84. A water jet 85 enters the tube '14 in order to cool the exhaust gases and it will be observed that drainage is provided from all of the pipes and chambers out through the exhaust line 83.

Fig. 9 shows a structure acoustically similar to those previously described but having constructural advantages particularly desirable in the larger sizes where it is difficult to bend the pipe. In this case the casing 96 is divided into chambers 9| and 92 by a non-central partition 93, preferably disposed even further off-center than shown. A pipe 94 enters the casing through one. of its headers 95, being preferably arranged axially of the cylindrical casing. A pipe 96 also enters the chamber 9| through the partition 93. Both of these pipes have lateral escape openings 91 formed as a continuous slot. Around both of these pipes is a larger tube 98 having a slot 99 positioned in alignment with the slot 91 and a second slot I02 on the opposite side. The tube 98 is preferably secured to the pipes 95 and 96 by welding at a point adjacent the edge of the slot. It will be observed that the large tube 98 can in this case be formed of a flat sheet bent into a cylinder and that no bending of pipe forms is required. A partition I is provided intermediate the opposite ends of the pipes 94 and 96. The gas enters through the pipe 94 which has an open end at a distance from the partition I00 substantially equal to the diameter of the pipe. Most of the gas turns back through the annular space I M between the pipe 94 and the tube 98, although a part of it can pass out through the slots. The gas then passes through the interior of the chamber III and by a reverse operation enters the pipe 96 through which it passes into the chamber 92, the construction of the parts in the latter chamber being the same as in the chamber 9|, no detailed discussion is necessary.

The structure shown in Figs. 11 and 12 is based upon the same general principle as that shown in Fig. 9 but employs a smaller structure and a lesser number of operations on the gas. In this case the chamber I has an inlet conduit I05 extending into it at one end. This inlet conduit has at least a portion of its length within the chamber provided with a slot I01. Surrounding the conduit is a tubular member I08 having a bottom I08 and a slot I I0 in registry with the slot I01 and a second slot' I I4 on the opposite side. The conduit and the tubular member are preferably secured to each other as by welding adjacent the edges of the slot. In this case the conduit I05 is shown as being positioned slightly eccentric with respect to the casing in order to give a larger expansion space at the side of the chamber remote from the slot. Here again the open end III of the conduit and the open end II2 of the tube are positioned at distances from the headers I09 and H3 on the order of the diameter of the conduit and tube respectively.

Fig. 13 shows a detail which may be applicable to any of the above structures. In this case the tube II5, extending within the casing III; and recurved upon itself, has one or more wedge shaped openings I I1 formed in its end. This end is secured as by welding to the header I I8. This increases the rigidity of the structure and may in some case be desirable, although the back pressure may be found to be greater than where a clear spacing between the header and the end of the tube is used.

The structure of Fig. 14 utilizes a chamber I20 to which it is desired to make inlet and outlet connections at one end only. One of the two conduits I2I is formed with a reverse bend I22 and terminates with an open end I23 adjacent the header I24. The second conduit I25 also enters through this header and 'extends throughout the length of the casing, having an open end I26 adjacent the opposite header I21. Both tubes are provided with lateral escape openings I28 along the lengths as shown.

Fig. is in general similar to the structure of Fig. 3 but illustrates how the invention may be adapted to a structure having more than two chambers. In this case one conduit I30 enters the first chamber I3I and is recurved upon itself as shown. The chamber I3I is joined to a chamber I32 by a U-shaped tube I33. A similar U-shaped tube I35 connects the chambers I32 and I34 and a recurved tube I36 extends from the chamber I35 to the outside. All tubes are provided with lateral escape openings as indicated.

From the variou embodiments described it is believed that it should be possible to design a satisfactory device for any intended use and with varying manufacturing requirements in mind. These embodiments are illustrative only, and the scope of the invention is defined not by them but by the appended claims.

I claim:

1. A silencer comprising a walled chamber and inlet and outlet passages leading into the chamber, at least one of said passages comprising a conduit extending into the chamber, said conduit being retroverted and terminating in an open end near its entrance into the chamber and being provided with one or more lateral escape openings distributed along the length of the conduit.

2. A silencer comprising a walled chamber and inlet and outlet passages leading into the chamber, at least one of said passages comprising a conduit extending into the chamber, said conduit being retroverted and terminating in an open end near its entrance into the chamber at a distance from the adjacent chamber wall on the order of the diameter of the conduit, and also being formed with one or more lateral escape openings distributed along the length of the conduit.

3. A silencer comprising a tubular casing having end walls, and an open-ended conduit extending through each end wall and formed with a return bend terminating in an open-end adjacent the end wall through which said conduit entered the casing and spaced therefrom a distance on the order of the diameter of the conduit, each of said conduits being formed with one or more lateral escape openings distributed along the length of the conduit.

4. A silencer comprising a chamber, an inlet opening in one end and an outlet opening in the other end thereof, and an open-ended conduit within the casing leading from the opening at one end of the casing towards the other end of the casing, bending back upon itself, and extending towards the first end of the casing to a distance therefrom on the order of the diameter of the conduit, said conduit having lateral escape openings formed in its wall.

5. A silencer comprising a chamber and a pair of open-ended tube entering the-chamber and serving as inlet and outlet conduits respectively, at least one of the tubes being bent back upon itself, the open ends of said tubes opening towards opposite ends of the casing and each of said tubes having lateral escape openings formed in its walls.

6. A silencer comprising a chamber and a pair of open-ended tube entering the chamber from opposite ends, inlet and outlet conduits connected to said tubes, each of said tubes being bent back upon itself into adjacency with the end of the chamber from which it entered the casing, each of said tubes being sufficiently unrestricted in diameter to cause no restriction in gas flow as determined by said inlet and outlet conduit, each of said tubes having one or more lateral escape openings in its wall distributed substantially throughout the course of said tube Within the casing.

7. A silencer comprisinga chamber and a pair of open-ended tubes entering the chamber from opposite ends, inlet and outlet conduits connected to said tubes, each of said tubes being bent back upon itself into adjacency with the end of the chamber from which it entered the casing, each of said tubes being sufficiently unrestricted in diameter to cause no restriction in gas flow as determined by said inlet and outlet conduit, each of said tubes having one or more lateral escape openings in its wall distributed substantially throughout the course of said tube within the casing, and an apertured partition interposed between the tubes.

8. A silencer having a plurality of open-ended tubes each bent upon itself, each tube having longitudinally distributed lateral escape openings formed in its walls, and a casing structure surrounding said tubes and having wall members positioned to prevent direct passage of gas between the open end of the tubes without passing through substantially the length of the casing structure, whereby gas will pass through one of said tubes, out through its open end and'lateral escape openings into the interior of the casing, and thence into the second tube through its open end and lateral escape openings.

9. A silencer comprising a casing forming an internal chamber, a conduit extending into the chamber and having a slot along one side and an inner open end, a tube surrounding said conduit and provided with a pair of opposed slots, one of which is in register with the slot in the conduit, said conduit and tube being secured together adjacent the edges of said registering slot, a closure for the tube spaced from the end of the conduit a distance on the order of the diameter of the conduit, and a second conduit extending into said casing.

10. A silencer comprising a casing forming an internal chamber, a pair of conduits entering the chamber from opposite ends thereof and spaced apart a distance on the order of twice the diameter of the conduits, the portion of each of said conduits within the chamber having a slot along one side and an open inner end, a tube surrounding said conduits and provided with a slot in register with the slots in the conduits and with a slot spaced therefrom, said conduits and tube being secured together adjacent the edges of the slots, and a partition secured interiorly of the tube intermediate-the ends of the conduits.

-11. A silencer comprising a chamber having a header at both ends, an open-ended retroverted conduit entering the chamber through a header at one end, said conduit having an open end adjacent said header, and a second conduit extending through the chamber andhaving an open end adjacent the header at the opposite end of the chamber, both of said conduits having lateral escape openings in their walls distributed along the portions of said conduits within the chamber.

12. A silencer comprising a pair of longitudinally adjacent walled chambers, an open-ended, retroverted, laterally a'pertured inlet pipe extending through the outer end wall of one chamher and terminating with its open end adjacent said wall, an open-ended, retroverted, laterally apertured outlet pipe extending through the opposite end Wall of the second chamber and terminating adjacent said end, and a laterally apertured open-ended pipe' connecting the chambers and extending substantially into at least one of them.

13. A silencer comprising a pair of longitudinally adjacent walled chambers, an open-ended, retroverted, laterally apertured inlet pipe extending through the outer end Wall of one chamber and terminating with its open end adjacent said wall, an open-ended, retroverted, laterally apertured outlet pipe extending through the opposite end wall of the second chamber and terminating adjacent said end, and an open-ended, U-shaped, laterally apertured pipe connecting the chambers and having its open ends directed towards the side walls thereof.

14. A silencer comprising a chamber, an openended pipe extending into the chamber and bent upon itself to form two adjacent legs, conduits connecting the legs, and an outlet conduit extending from the casing.

JOHN P. TYSKEWICZ.

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