US2111537A - Muffler - Google Patents

Description

March 15, 1938. Q G NQBLIITT ET AL 2,111,537

MUFFLER Filed Jan. '7, 1955 3 Sheets Sheet 1 Wag/y March 15, 1938. Q. G. INOBLITT ET AL MUFFLER Filed Jafi. 7, 19:55

3 Sheets-Sheet 2 W w WU MW Patented Mar. 15, 1938 UNITED STATES PATENT OFFICE MUFFLER Indiana. I

Application January 7, 1935, Serial No. 632

7 Claims.

This invention relates to devices for silencing noises accompanying gas flow and particularly to mufflers for silencing the exhaust of internal combustion engines.

It frequently happens that mufflers otherwise satisfactory will be resonant to sound-vibrations of a particular frequency and that, while the muiiler will in general provide adequate silencing, objectionable noises of rather definite pitch are produced at certain engine speeds. To overcome this, resort has been had to the use of resonating chambers which, as has been known for many years, have the capability of absorbing sounds of characteristic frequencies from a sound field.

Our invention is primarily concerned with muiilers of the so-called reverse-flow type in which the gases to be silenced are passed back and forth successively through a set of longitudinally co-extensive silencing tubes, and it is our object to incorporate an effective resonating chamber in such a muiller and to produce an assembly which will be compact and which can be simply and economically manufactured.

In carrying out our invention we provide for the muiiier an outer casing within which are disposed the longitudinally co-extensive silencing tubes, such tubes being interconnected by passages formed between transverse partitions located within the casing at the ends of the tubes. The resonating chamber is located at one side of one of these partitions, preferably at one end of the muffler, passage by means of an opening in the partition separating them. If the resonating chamber is located at one end of the muiiler there may extend through it a pipe for Supplying the gases to the first silencing tube or for conveying such gases from the last silencing tube.

The accompanying drawings illustrate our invention: Fig. 1 is a side elevation of a muiiler of circular cross-section with portions thereof broken away and shown-in section on the line l-I of Fig. 2; Figs. 2 and 3 are front and rear end elevations respectively of the muiiler of Fig. 1; Fig. 4 is a top plan view of a mufiier of generally oval cross-section provided with resonating chambers at both. ends, parts of the muiller being broken away to illustrate details of interior construction; Fig. 5 is an end elevation of the muiiler of Fig. 4 with parts thereof broken away and shown in transverse cross-section; Fig. 6 is a top plan view of another muiiler of oval cross-section showing a difierent arrangement of silencing tubes and somewhat difierent internal construcazid communicates with the adjacent tion; and Fig. 7 is a fragmental transverse section on the line 'I-l of Fig. 6.

The muiiier shown in Fig. 1 comprises a cylindrical shell lb of circular cross-section closed at its inlet end by a head it and at its discharge end by a head ii. Within the casing in and near one end thereof, here shown as the inlet end, we dispose a transverse partition I2 cooperating with the adjacent end-head of the mufiler to form a resonating chamber I3. Spaced inwardly from the head ii and the resonating-chamber partition l2 are main transverse partitions l4 and I5 between which extend three silencing tubes ll, l8, and I9 through which the exhaust gases of an internal combustion engine successively flow.

At a multiplicity of points along its length, each of the tubes l1, l8, and I5 is provided with openings of relatively small cross-section which aiford communication between the interior of the tube and the space around it. Conveniently, each tube is formed of a pair of complementary sheet-metal stampings generally semi-circular in cross-section and provided along their longitudinal edges with flanges which are secured together, as by welding. We find it advisable to so arrange the tubes that some of the louvers slope outwardly in the general direction of gas-flow while others slope inwardly. As indicated in Fig. 1, the louvers of the tubes ii and i8 slope outwardly in the general direction of gas-flow through the tubes, while the louvers of the tube l9 slope inwardly.

The space between the two main transverse partitions i4 and 65 may be divided into compartments by auxiliary transverse partitions 2| and 22, and each of such compartments may be further divided into chambers by longitudinally extending partitions 23 disposed between the tubes ll, I8, and I9, as indicated in Fig. 2.

The head H at the inlet end of the muffler is provided with an opening to permit the admission of the gases to be silenced, such opening com municating with the first silencing tube ll through a nipple 25 which extends longitudinally through the resonating chamber l3 and continues across the space between the partitions I2 and H. Conveniently, the head II is provided with an annular flange 26 for the reception of the front end of the nipple 25, such nipple having an internal diameter enabling it to receive the exhaust pipe 21 leading from the engine.

The exhaust gases passing from the last silencing tube I! are conveyed through a nipple 30 which extends across the space between the partition l5 and head H and projects beyond the head II where it is adapted for attachment to a suitable tail-pipe (not shown).

At its rear end, the first silencing tube I'I discharges into the transverse passage provided between the partition I5 and head II. This same passage communicates with'the rear end of the intermediate tube I8, the front end of such intermediate tube and the front end of the last tube I9 communuicating with the passage between the partitions I2 and I4. Gases supplied to the muiiier, therefore, flow through the nipple 25 and tube II into the transverse passage at the rear end of the muiiier. From this passage the gases flow through the tube I8 into the passage between the partitions I2 and I4 and thence through the tube I9 and nipple 30. As the gases pass through the tubes II, I8, and I9, gases in high pressure zones escape outwardly through the openings in the tubes into the chambers surrounding them and then return through such openings when a zone of low-pressure gases passes.

The partition I2 is provided with an opening affording communication between the resonating chamber I3 and the passage located between the partitions I2 and I4. The resonating characteristics of the resonating chamber I3 are improved if the passage through which it communicates with the space between the partitions I2 and I4 has an appreciable longitudinal extent, and to provide such a passage, we may displace the metal of the partition I2 to form a bellmouthed opening 35.

We find that the location of the opening 35 in the crosssectional plane of the muffler is of some importance, and we prefer to locate it in alinement with one of the tubes I8 and I9 which communicate with the space between the partitions I2 and I4. In the drawings, the opening 35 is shown as in alinement with the tube I8 where the gases emerging from such tube will impinge upon it. We find this arrangement to have a slight advantage when the mumer otherwise has a tendency to resonate upon acceleration of the associated engine. If the muiller otherwise has a tendency to resonate upon deceleration of the engine, some advantage attaches to locating the opening 35 in line with the tube I9.

The resonating chamber I3 may be proportioned to absorb sound of any desired frequency from the sound field within the muffler. In practice, it is proportioned to absorb the objectionable sound which would be produced under resonating conditions in the absence of a resonating chamber.

The muiller illustrated in Figs. 4 and 5 is generally similar to that shown in Figs. 1, 2, and 3 except that its casing I8 is of oval conformation rather than circular and is provided with resonating chambers I3 and I3 at both ends instead of only at one end, the resonating chamber at the rear end of the muiller being defined by the rear head II and by a transverse partition I2 spaced axially inwardly therefrom. The two resonating chambers I3 and I3 may be made to be resonant to difierent frequencies and it is thus possible, through the use-of two resonating chambers, to absorb objectionable sounds of two different pitches. a

In the muffler shown in Figs. 4 and 5, the opening 35 of the resonating chamber I3 atthe rear end of .the muiller is shown as located in alinement with the first silencing tube II so that the gases discharged from such tube will impinge upon the opening. This location of the opening 35', as pointed out above, is preferred when the particular sound which the resonating chamber I3 is to absorb occurs upon acceleration of the engine. On the other hand, the opening 35 of the resonating chamber I3 is located opposite the last silencing tube I9, which arrangement is preferred when the noise that the chamber I3 is to absorb occurs upon deceleration of the engine.

With an oval muiller, it is possible to exercise some selection in disposing the inlet and outlet openings which are to communicate respectively with the exhaust pipe and the tail pipe to suit the particular automobile in which the muiiier is to be used. Thus, the intermediate silencing tube I8 may be located centrally of the casing, as is shown in Figs. 4 and 5, or at one side of the casing, as indicated in Figs. 6 and '7. If the intermediate tube I8 is located at one side of the casing, the first tube I! may be located either centrally or at the other side, the former arrangement being illustrated in Figs. 6 and '7.

Other differences between the muilier of Figs. 4 and 5 and the mufiler of Figs. 6 and 7 include the disposition in the mufiler of Figs. 6 and 7, of the opening 35' in line with the intermediate silencing tube I8 and the provision of louvers in some of the longitudinal partitions 23. These louvers permit a small amount of the gases to bypass portions of the silencing tubes. In the specific arrangement indicated, the louvers in the partition 23 are provided only between the transverse partitions 2| and 22. We find this arrangement to be of advantage in decreasing back presi sure produced by the muiller.

We claim as our invention I 1. In a muiller for silencing flowing gases, an elongated casing, two gas-conveying longitudinal silencing tubes located in said casing and having longitudinally co-extensive portions, said mumer being provided with a transverse passage interconnecting adjacent ends of said two silencing tubes, and a resonating chamber communicating with said transverse passage at a point opposite and in substantial alinement with that one of said silencing tubes which conveys gases from said transverse passage.

2. In a muiller for silencing flowing gases; an elongated casing provided with end closures, a transverse wall disposed within said casing and near one end thereof and co-operating with the adjacent end closure to form a resonating chamber, two longitudinally spaced transverse partitions disposed inwardly from said wall and from the opposite end-closure to define transversegas passages, three gas-conveying longitudinal silencing tubes disposed in the space between said partitions and forming with said transverse passages a tortuous passage, conduits for supplying gases to one end of one of said tubes and for conveying gases from the opposite end of another tube, said transverse wall being provided with an opening afiording communication between said resonating chamber and the adjacent transverse gas passage. I

3. In a muiller for silencing flowing gases, an elongated casing,'two gas-conveying longitudinal silencing tubes located in said casing and having longitudinally co-extensive portions, said mufller being provided with a transverse passage interconnecting adjacent ends of said two silencing tubes, a pair of longitudinally spaced main transverse partitions disposed within said casing and defining a chamber through which the longitudinally co-extensive portions of said tubes pass, one or more auxiliary partitions dividing the chamber between said main partitions into subchambers, a longitudinal partition disposed within said chamber between said tubes, each of said silencing tubes being provided ata multiplicity of points along its length with restricted openings, and said longitudinal partition within one of said sub-chambers being provided with a longitudinal series of restricted gas-passing openings.

4. A mufiler for silencing flowing gases, comprising a casing, a partition dividing the interior of said easing into two compartments, said 'mufller being provided with a gas passage having two sections disposed respectively in such compartments and through which at least a portion of the gases successively pass, said passage-sections being generally parallel and so arranged that the gases pass through them in opposite directions, the walls of each of said passage sections being provided at a multiplicity of points along its length with restricted openings, and said partition being provided with a longitudinal series of restricted openings.

5. A mufller for silencing flowing gases, comprising a casing, a partition dividing the interior of said casing into two compartments, said mufiler being provided with a gas passage having two sections disposed respectively in such compartments and through which sections at least a portion of the gases successively pass, the wall ofeach of said passage sections being provided at a multiplicity of points along its length with restricted opening's, and said partition being provided with a longitudinal series of restricted openings.

6. A mufiler as set forth in claim 5 with the addition that the openings in the wall of said passage-sections are relatively long and narrow and extend generally circumferentially of the wall of the passage-section.

'7. In a mufiler for silencing flowing gases, an elongated casing having end closures, a transverse wall disposed within said casing near one end and defining in co-operation with one end closure a resonating chamber, and means located within said casing between the other end closure and said wall for defining a tortuous gas-passage including portions with perforated walls and, intermediate such portions with perforated walls, a

transverse passage-portion defined in part by

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