US2229913A

US2229913A - Silencer

Info

Publication number: US2229913A
Authority: US
Publication date: 1941-01-28
Anticipated expiration: 1958-01-28

Description

Jan. 28, 1941. J. G. BLANCHARD SILENCER Filed Dec. 3, 1958 4. A :A Y2., w Illy! MNHN..

Patented Jan. 28, 1941 UNITED STATES SILENCER Joseph George Blanchard, London, England, assignor of one-half to Cecil Gordon Vokes, London, England Application December 3, 1938, Serial No. 243,837

In GreatBritain December 9, 1937 9 Claims.

This invention relates to silencers for the passage of gaseous currents.

It is an object of the invention to provide a silencer in which gases are caused to converge and enter into mutual collision in the immediate vicinity of the mouth of an expansion chamber and to escape, after` collision, in a direction substantially at right angles to the plane or planes in which they converge.

With the above and other objects in view, the invention consists in the improved combinations and arrangements contained in the embodiments now to be described in detail, and features of which are set out in the claims which follow.

In the drawing:

Figure l is a longitudinal sectional view of an exhaust silencer for an internal combustion engine.

Figure 2 is a cross section of same on the line 2-2 of Figure l, looking in the direction o! the arrow.

Figure 3 is a detail cross section through the member 9, on the line 3-3 of Figure 1.

` Figure 4 is a detail crossv section through the member I0, on the line 4-4 of Figure 1.

The silencer shown comprises a collision unit mounted within a. vacuum chamber.

The collision unit comprises hollow outer and inner members I and 2 respectively, of which the outer member I has a frusto-conical portion 3 connected at its base to a portion 4 which is defined chiefly by a surface of revolution formed by an arc revolving about the axis of the frustum. The portion 4 is formed with a central aperture 5 which is shown as of diameter very slightly larger than the internal diameter of the small end of the frusto-conical portion. but, though this is preferred, it might be of equal diameter.

The inner member 2 has a conical portion 6, of base angle smaller than that of the Irustoconical portion 3, and a portion I somewhat similar to the portion 4 of the member I and provided with a central aperture 8 of substantially the same size as the aperture 5.

The member 2 is mounted concentrically within the member I by means of lugs 9 and I0, of which the latter at least are of streamline form.

In use, the outer member I receives exhaust gases at its smaller end by way of an extension VII forming an inlet pipe. The gases envelop the inner member and traverse the annular path of varying cross-sectional dimensions formed between the two members, changing direction in the part ci the path formed between the portions 4 and 1 to enter the cylindrical space or zone sltuated between the apertures 5 and 8, where general collision occurs between gas particles converging upon the axis of the silencer from all sides as viewed along the axis. After collision gases may pass into the interior of the inner member by way of theV aperture 8 and out through the aperture 5 of theouter member, the paths followed by the gases in passing in veither direction forming iigures of substantially conical or cylindrical shape coaxial with the axis of the collision zone. The interior of the inner member acts as a sort of cushioning chamber, and the majority of gases will pass, immediately after collision, through the aperture 5. The streamlined lugs I0 are, however, hollow and provide paths whereby the pressure within the member 2 may be relieved when pressure peaks occur.

The relative shapes and dimensions of the inner and outer members are preferably such that the annular path between them is of substantially constant cross-sectional area throughout its length: this ensures that there is substantially no reduction in the speed of the gases due to expansion with corresponding reduction of the energy available for collision.

The vacuum chamber is formed by a casing I2 which surrounds and extends beyond the outlet end of the collision unit.

A frusta-conical tube I3, which is secured to the portion 4 of the member I and, by lugs II, to the casing I2. projects, at its smaller end, into the largerend of another frusto-conical tube I4 and receives the gases which pass through the aperture Stafter collision.

The tube I4, which is secured to the tube I3 by lugs I5, delivers the gases to an exit pipe IB and the gases exert an injector eilect upon the interior of the casing I2, by way of the annular space between the tubes I3 and I4, with the result that a vacuum is formed within the casing surrounding the collision unit, the silencing eiect of the latter being thereby augmented.

In the silencer just described, the gases enter the collision zone of the collision unit by Way of a single aperture which surrounds the zone: since the arrangement illustrated might be modified so that the gases enter the collision Zone from a plurality of, paths or apertures formed, for example, by partitions in planes parallel or inclined to the longitudinal axis of the silencer, the term a'path as used in the claims is intended to include cases in which the gases travel by an equivalent arrangement of paths Further the arrangement is such that the gases converge upon the axis of the collision zone in a plane at right angles to the axis but the term from opposite directions is used in the claims to include cases in which the gases travel in planes slightly inclined either forwardly or backwardly with respect to the axis.

A single collision unit similar to that described above has been found to provide a satisfactory degree of silence for the exhaust ofan internal combustion engine but it maybe desirable in some cases, to combine two or more collision units. Thus, two or more units for causing collision in the manner described may be arranged in series or in parallel in a common casing.

It is to be understood that the above specific descriptions of silencers for the passage of gaseous currents have been given by way of example and that various modifications may be made without departing from the invention.

I claim:

1. A silencer or silencer unit for the passage of gaseous currents comprising a hollow body having an inlet at one end, and a second hollow body within the iirst hollow body and spaced therefrom to provide an annular passage leading from the inlet, the walls of hollowbodies defining the annular passage being turned inwardly at the end remote from the inlet to define a circumferential slot surrounding the longitudinal axis of the hollow bodies, whereby gases passing from the inlet through the annular passage are caused to iiow inwardly towards the longitudinal axis of the silencer from all radial directions for mutual collision and subsequent dispersal in both directions along the longitudinal axis.

2. A silencer or silencer unit for the passage of gaseous currents comprising an inner hollow member closed at one end and having an opening at the other end in a plane at right angles to the axis of the body, an outer hollow member open at both ends surrounding this inner member and spaced therefrom, the opening in this outer member at the end adjacent to the open end of the inner member being of substantially the same diameter as the opening in the inner member and in a plane parallel to but spaced from the plane of the opening in the inner member, the opening in the other end of this outer member lying in a plane at right angles to the axis of the unit adjacent to the closed end of the inner member and an '.nlet tube surrounding this last mentioned opening in the outer member.

3. A silencer or silencer unit for the passage of gaseous currents comprising an inner hollow member closed at one end and having an opening "aft the other end in a plane at right angles to the axis of the body, an outer hollow member open at both ends surrounding this inner member and spaced therefrom, the opening in this outer member at the end adjacent to the open end -of the inner member being of substantially the same diameter as the opening in the inner member and in a plane ,parallel to but spaced from the plane of the opening in the inner member, the opening in the other end of this outer member lying in a plane at right angles to the axis of the unit adjacent to the closed end of the inner member, an inlet tube surrounding this last mentioned opening in the outer member and hollow lugs spacing the open end of the inner hollow member from the adjacent end of the outer member, these lugs being circumferentially arranged around the openings in this end of the inner and outer members and providing passages connecting the interior of the inner hollow member with the outllde of the unit.

4. A silencer or silencer unit for the passage of gaseous currents comprising a hollow conical member having an opening in the base thereof, an outer member enclosing the conical member and spaced therefrom, this outer member having a frusta-conical portion of which the smaller end is adjacent to the apex of the inner conical member and having in its larger end an opening of substantially the same diameter as the opening in the base of the conical member, this end of the outer member being spaced longitudinally from the base of the conical member so as to form therewith a circumferential passage through which gas may be directed inwardly from all radial directions and an inlet member surrounding the small open end of the outer member.

5. A silencer or silencer unit for the passage of gaseous currents as deiined in claim 4 in which hollow lugs are arranged between the base of the conical member and the adjacent end of the outer member, these hollow lugs being spaced circumferentially around the opening therein and providing passages connecting the interior of the cone with the outside of the unit.

6. A silencer or silencer unit as defined in claim 4 in which the angle of taper of the frustoconical portion of the outer member is so related to the base angle of the inner conical member that the annular path formed between the inner and outer members is of substantially constant cross-sectional area.

'7. A silencer comprising in combination a silencer unit comprising a hollow body having an inlet at one end, and a second hollow body mounted within the nrst hollow body and spaced therefrom to provide an annular passage leading from the inlet, the walls of these hollow bodies defining this passage being turned inwardly at the end remote from the inlet to define a circumferential slot surrounding the longitudinal axis of the hollow bodies, a chamber surrounding this unit and extending beyond the outlet therefrom and means within this chamber whereby a vac'- uum is formed in the chamber bythe injector or entraining eifect of gases passing longitudinally of the chamber after mutual collision within the zone of the silencer unit surrounded by the aforesaid circumferential slot.

8. A silencer for the passage of gaseous current comprising an inner hollow member closed at one end and having an opening at the other end in a plane at right angles to the axis of the body, an outer hollow member open at both ends surrounding this inner member and spaced therefrom, the opening in this outer member at the end adjacent to the open end of the inner member being of substantially the same diameter as the opening in the inner member, and in a plane parallel to but spaced from the plane of the opening in the inner member, the opening in the other end of this outer member lying in a plane at right angles to the axis of the unit adjacent to the closed end of the inner member, an inlet tube surrounding this last mentioned opening in the outer member, a casing enclosing the outer member and extending beyond the outlet therefrom and injector means whereby gases after passage from the outlet of the outer member tend to form a vacuum within the casing.

9-. A silencer for the passage of gaseous currents comprising an inner hollow member closed at one end and having an opening at the other end in a plane at right angles to the axis of the body, an outer hollow member open at both ends surrounding this inner member and spaced therefrom, the opening in this outer member at the end Vadjacent to the open end of the inner member being of substantially the same diameter as the opening in the inner member and in a. plane parallel to but spaced from the plane of the opening in the inner member, the opening in the other end of this outer member lying in a piane at right angles to the axis of the unit adjacent to the closed end of the inner member, an inlet tube surrounding this last mentioned opening in the outer member, a casing'enclosing the outer member and extending beyond the outfiet therefrom, said casing being closed at each end and having an outlet in the end remote from the inlet tube, a frusta-conical member within the chamber surrounding this outlet and a second truste-conical member surrounding the opening in the end of the outer member and entering within the end of the first Irusto-eourcal mem.- ber in spaced relation thereto. Y

J GEORGE-BLANCHARD.