US2075088A

US2075088A - Means for silencing gaseous currents

Info

Publication number: US2075088A
Application number: US52434A
Authority: US
Inventors: Blanchard Joseph
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-12-18
Filing date: 1935-11-30
Publication date: 1937-03-30
Anticipated expiration: 1954-03-30

Description

March 30, 1937. J. BLANCHARD MEANS FOR SILENCING GASEOUS CURRENTS Filed NOV. 50, 1955 Patented Mar. 30, 1937 t UNITED STATES PATENT oFFicE Joseph motora, London, England, f1

o! one-half to Cecil asigna' Gordon Votes, london,

Application November 30,1935, sono: No. 52,434 In Great Britain December 18, 1934 1, This invention relates to silencers for pulsating gaseous currents, such as the exhaust of ,internal combustion engines, theair intake of internal combustion engines or compressors, the

exhaust of pneumaticengines and the like.

It is an object ofthe invention to provide a silencer in which a. series of units or elements are employed each comprising' a passage into which an inlet pipe projects at one end to form an injector eiective upon some or all of the 'contents of a space situated between the passage and an outer wall and communicating'also with the other end of thepassage.

'.It is a further object' of the invention to provide a silencer having'inner, intermediate and outer paths for gases and in which gases traversing the intermediate path'are subject to the in- :lector effect of gases traversingl the inner path.

With these and other objects in view, the invention also consists in the new or improved teatures, combinations and arrangements of parts embodied in the specific embodiments now to l'be described in detail, the novel aspects of the invention being pointed out in the claims which follow.

In the drawing.: .Y

Figure 1 is a longitudinal section through a silencer, u

Figure 2 is a similar section through part of a 30 modified form o f silencer, l E

Figure 3 is a similar section through part of a further form of silencer, and

Figure 4 is a section on the line IV--IV of Figure 3. .A y

The cylindrical outer casing l of the silencer shown in Figure 1 has inlet and outlet pipes 2 and 3 respectively and has mounted preferably concentrically within it a cylinder 4 of reticulated 'material supported by perforated annuli 5. 40 A series of silencer units 6 is arranged within the reticulated cylinder, which, as shown, does notv extend the whole length ,of the silencer but is of such length'as to leave at the outlet end a chamber l which is not occupied by silencer 45 units or by part of the reticulated cylinder.

Each of the silencer units 6 comprises a pair of end plates 8 and 9 and a tube Il) of Venturi section. The end plates 8 and 9 comprise each an outer annular portion Il and a centralin- 50 wardly dished and apertured portion llof greater length joined by an annular channel of substantially segmental cross section. 'I'he end plates 8 and 9 oi' each unit are secured at the opposite ends'oi' the Venturi tube 55 i0 of that unit by means of radial tongues il weiden to the tube and the portions l2 of the end plates respectively. The apertured. portion i l of the plate 8 forms aninlet passage projecting -into the passage formed by the Venturi tube and tube at the outlet end thereof, and thus places this end also of the Venturi passage into com- 15 munication with .the space surrounding it.

The inlet passage of the iirst silencer unit, that on the `extreme left inY'Figure .1, receives gases direct from the inlet pipe 2 of the silencer and leads theminto the Venturi passage of that unit. These gases pass to the far end of the Venturi passage and it will be seen from the drawing that a straight-through path `is provided for them to the outlet pipe 3 by way of the outlet passage of the rst unit and through the succeeding units. Some parts of the gases, however, nd their way by the passage i6 to the space l5 the contents of which are subject to the injector action of the gases entering through the inlet passage. This injector action has the effect of returning to the main flow, by Way of the opening I4, some of the gases withdrawn to the space l5 by the passagel. v

The action vof the succeeding units is similar to that described above, and the gases which. pass through the outlet passage of the final, or extreme right hand, unit are led towards the outlet pipe 3 by a conical irustum l1 of reticulated material situated within the chamber 1. Some of the gases` withdrawn from the main or central stream to the portions i 5 of the space surrounding the Venturi passages of the various units are not'returned direct to the main flow by the injector action. which caused their withdrawal but pass by Way of the reticulations of the cylinder 4, to

the annular portion of the space vwhich is situated between the cylinder and the outer casing l. Some of the gases thus passing may be returned tothe main ow by the injector action of succeeding units, but the remainder are drawn towards the outlet pipe 3 by the entraining action of the high velocity gas stream leaving the small end of the cone.

It will be seen from the above description that some of the gases forming the pulsating currents are withdrawn from the main stream and returned to it at various points, thus tending to break up or reduce the original pulsations. The lengths of the members I may vary in accord"- 5 ance with the velocity of the gases entering at the inlet pipe at the normal speed of the engine from which they come, or at the speed at which most efdcient silencing is required, and/or in accord- .ance with the volume of gas to be evacuated, and the lengths of the members I0 in succeeding elements or units may be so chosen relatively to each other that a substantially continuous or nonpulsating ow of gases at the exit orifice is obtained. l5 If desired, provision may be made for causing whirling motion of the gases passing through the silencer. Thus, for instance, lsuitable deflector plates may be provided for causing whirling motion of the gases within the chamber 'l,` either within or without the conical frustum I'l.

Whirling motion, if provided for in silencers according to the present invention, may be in a lsingle sense or it may be periodically reversed, and gases may be divided into two oppositely directed streams which meet with an effect of collision or turbulence.

if it is desired to limit the space for expansion allowed to the gases, a fairing sleeve may be provided surrounding the Venturi tube, thus reducing the effective volume oi the space i5. ln Figure l a sleeve it of reticulated material is shown surrounding the Venturi tube l0 of 'the extreme right-hand unit, whereby a cushioning4 space i5 is formed which may serve to absorb pressure peaks in the gases traversing the space i5.

Although it is preferred to employ a, Venturi tube as part of the injector system, the injector action may be obtained by the combination ci an inlet passage leading into a second passage of any suitable form so as to leave an opening between the inlet passage and the second passage whereby an injector eect is produced upon the space surrounding the latter. rIfhe rformation of the inlet and outlet passages integrally with the end plates of the units is not, of course, essential, but the curved portions of the end plates illustrated serve as smooth guiding surfaces for the gases leaving and entering the main iiow in their passage to and from the space I5.

In some cases the space surrounding the path of the main gas iiow may be divided otherwise than by the Wall oi the reticulated cylinder or by a fairing sleeve as described above, such other manner of division being alternative or additional to those shown in Figure l. Thus, for example, a member may be provided surrounding the Venturi tube, or its equivalent, but making contact therewith at the outlet end only, the other end being secured to the outer annular portion of the end plate 8 of the unit. A space is thus formed surrounding the main flow of gases and subject to the injector action of those gases since the space is in communication with the opening I4. A vacuum is thus formed 'surrounding the path of the main gas iiowand acts as a deadener of sound. Such a unit is shown in Figure 2, later to be referred to.

The silencer illustrated provides a straightthrough passage for the gases, which passage may be followed by the eye from the inlet 2 to the outlet 3. Such a completely straight path may not always be provided, owing, for example, to

the slight off-setting of succeeding silencer units, or if several series of units are employed in parallel with common inlet and/or outlet pipes, or

,unitasthecasemayba where the silencer includes whirling or collison plates.

Figure2 illustrates a form of silencer comprising two diierent types of unit in series, that shown on the left in the figure being of simple 5 form from the manufacturing view point, but being generally suitable for use only in cases in which overall 'diameter is not of great importance.

In this form, the silencer unit shown on the left comprises apair of members 20 and 2| each l0 formed from a hemispherical stamping and having an internal apertured

neck

22 or 23; the

necks

22 and 23 form the inlet and outlet passage re-` spectively of the unit. A Venturi tube I0 is secured in position by means of tongues I3, as l5 in the form previously illustrated, with its ends enclosing the ends of the necks.

It will be seen from the drawing that the interior of the unit communicates with the interior of the rest of the silencer only `by its inlet and 20 outlet passages .so that all gases withdrawn through the passage i6 to the space surrounding the Venturi tube are returned to the main flow by injector action by way of the opening I4.

The unit is shown mounted with its portions 20 25 and 2| in actual contact with the outer casing I of the silencer. If it is preferred, the outer casing may be made of greater relative cross section so that the shell of the unit is spaced therefrom, with orvwithout the intervention vof packing ma- 30 terial.

In a still simpler form of this kind of unit, the heini-spherical stampings may be apertured for the reception of inlet and outlet pipes. In such a form it might be found necessary to provide 35 guiding members surrounding these inlet and outlet pipes to provide smooth paths for the bypassed gases similar to those produced in the form illustrated.

The unit shown on the right in the ligure com- 40 prises a pair of end plates 8 and 9 similar to those lshown in Figure l and a Venturi tube ||l the ends of which surround the inwardly projecting portions |2 of the end plates to which the tube is secured by tongues I3. A frustoconical sleeve 3| 45 surrounds thetube I0 and is secured at one end to the outlet end of that tube and at the other end to the outer annular portion of the end plate 8.

The space 32 formed between the tube IB and 50 the sleeve 3| is subject to the injector eiect of the gases entering through the inlet of the unit with the result that a vacuum is set up in this space. Such a vacuum situated between the path of the gases through the venturi and the outer casing 55 of the silencer acts as a deadener of sound.

Holes 33 are formed in the outer portion of the end'plate 3 to prevent a high pressure zone being set up in the space 34 formed between the sleeve 3| and the outer wall I of the silencer. 60

If it is desirable to produce a silencer having a relatively small dimension in one direction, the construction illustrated in Figures 3 and 4 may be adopted. According to this construction, inlet and

outlet pipes

24 and 25 respectively project 65 into a. tube 26 of greater diameter mounted within thev casing I, the internal dimension oiwhich in one directionis but slightlyogreater than the external diameter of the tube 26. The annular spaces formed between the inner surface of the 70 tube 26 and thebuter surfaces oi' the

pipes

24 and 25 place the interior of the tube 26 into communication with

spaces

21 and 28 respectively formed at theIv opposite ends of the silencer or The spaces 21 and "-15 ate guiding members for the by-passed gases may be provided and packing material may be inserted,

if desired, in the spacesvbetween the tubes and casing appearing in Figure 5. Alternatively, the

whole of the interior of the casing not occupied by the

pipes

24 and 25 and tube 26 may be employed for the return of the gases, the pipes 29 and 43l) being omitted, if the freedom of expansion l5 of the gases thus permitted is not undesirable.

The above descriptions of specific forms of silencer are given merely as examples of practical ways of carrying out the invention and various modifications may be made without departing from the invention.

I claimt- 1. A silencer for pulsating gaseous currents including a series of elements each comprising an inlet passage, a second passage which has a substantially imperforate wall and into which said inlet passage projects with an appropriate opening to form an injector, an outer wall forming between itself and the wall of said second passage a space to which the end of said second passage 30 remote from said inlet passage is open and upon some or all of the contents of which the injector formed by said inlet and second passages is effective.

2. A silencer for pulsating gaseous currents inc luding a series of elements each comprising an outer wall, an inlet passage, a second passage receiving the end of said inlet passage to form an injector effective, vupon the contents of a space formed between said outer wall and the wall of said second passage, a passage connecting said second passage to aspace formed between its wall and said outer wall, and open to a space formed within said outer wall to provide a path for gases common to all elements and alternative to those provided by the second passages thereof.

3. A silencer for pulsating gaseous currents comprising intercommunicating inner, intermediate and outer paths for gases, and an inlet passage projecting into said inner path to form an injector effective upon gases traversing said intermediate path.

4. A silencer for pulsating gaseous currents comprising a passage, an outer wall enclosing a space between itself and the wall oi said passage, a wall dividing said space into two portions open to opposite ends of said passage, and an inlet pipe projecting into said passage with an appropriate opening to form an injector which tends to draw towards the inlet end of the silencer the contents of thatA portion of said space which is open to the inlet end of said passage.

5. A silencer for pulsating gaseous currents comprising a passage, an outer wall forming a space between itself and the wall of said passage, an inlet pipe projecting into one end of 'said passage to form an injector tending to reinjector, an outer wall forming a space betweenV itself and the wall of said second passage, said space being open to said second passage at both ends thereof and subject to the action of said injector which tends to return to said second passage gases which have passed therefrom, and a passage formed within said outer wall and forming, for gases which have passed from said second passage to said space, a path alternative to that provided by said second passage.

7. A silencer for pulsating gaseous currents comprising a passage, an inlet passage projecting into said first mentioned passage to form an injector, an outer.wall forming between itself and the wall of said first mentioned passage a space which is open to said first mentioned passage at both ends thereof and of which the contents are subject to the action of said injector, and a reticulated wall dividing said space into two portions.

8. A silencer for pulsating gaseous currents comprising an outer casing, a tube of Venturi section arranged within said outer casing and an inlet pipe for gases projecting into said Venturi tube to form an injector effective upon ythe contents of a space situated between the wall of said Venturi tube and the wall of said outer casing.

9. A silencer for pulsating gaseous currents comprising a tube mounted within a casing, an inlet pipe projecting into said tube with an appropriate opening to form an injector effective upon the contents of a space situated between said tube and said casing, and a sleeve surrounding said tube.

10. A silencer as claimed in claim 9 wherein said sleeve is of reticulated material.

11. A unit for use in a silencer comprising a pair of end plates of which each has an inwardly dished and `apertured portion, and a tube the ends of which surround with clearance the ends of the inwardly dished and apertured portions ofthe said end plates.

JOSEPH BLANCHARD.