US2009343A - Muffler - Google Patents

Description

P. G. PEIK July 23, 1935.

MUFFLER 2 Shets-Sheet l Filed July 60, 1932 a o n n v n nl sul nu l Si N PHUL E* PE/K July 23, 1935. P. G. PEIK 2,009,343

MUFFLER Filed Ju'ly 30, 1932 2 Sheets-Sheet 2 3mm PHUL G- PE'K Patented July 23, 1935 UNITED STATES PATENT oFFlcE MUFrLEa tion of Ohio Application July 30, 1932, ySerial No. 626,280

1 Claim.

vide a mufller having a very high degree of silencing or muilling eciency and relatively low back pressure.

A further object of the invention is to provide amuiiier in which condensation will be eliminated under all operating conditions.

Another object of the invention is the provision of a muffler capable of scavenging efficiently under all operating conditions.

A still further object of the invention is to provide an extremely compact structure adapted to occupy but very little space, particularly in its longitudinal dimension.

Other objects and advantages of the invention will be apparent as the specification is considered in connection with the accompanying drawings, in which:

Figure l is a longitudinal sectional view through a muffler ac'cording to the invention, the section being taken on line I-I of Figure 2;

Figure 2 is a cross sectional view on line 2-2 of Figure 1;

Figure 3 is a perspective view of the skeleton inset supporting the tubes and subdividingthe cylinder in parallel compartments;

Figure 4 is a longitudinal sectional view oi a modified form of the muier according to the invention, the section being taken on line 3-3 of Figure 5; l

Figure 5 is a cross sectional view on line 5-5 of Figure 4; and

Figure 6 is a perspective view partly broken away of the skeleton inset supporting the tubes and subdividing the cylinder in parallel compartments.

Referring more particularly to the drawings, my improved muflier comprises an outer preferably cylindrical sheet metal shell I, closed at its ends by end walls 2, also of sheet metal. Inner walls or partitions 3 slightly spaced from end walls 2 form narrow spaces 4 at the ends of the cylinder which spaces are filled with pads of 'foraminous sound absorbing material 5, such as expanded mica, steel wool and-the like. These packed end sound absorbing spaces are not absolutely necessary to the proper functioning of the muier, and therefore may in most instances be eliminated.

Mounted within the shell l. are a series of parallel perforated tubes 6, l and 8 through which exhaust gases pass in the order named. Apertured sheet metal disks 9 within and adjacent each end of cylinder I serve as supports for tubes 6, 'I and 8 and also form chambers I0 and I I, between said disks and the end walls of the cylinder for reversing the flow of gas. Tube 6 extends at its intake end through end wall 2 at the intake end of the cylinder for connection with the engine exhaust, not shown, and at its other end exhausts into reverse flow chamber I0. The tube 8, communicates with chamber II at its inner end and exhausts through end wall 2 at the exhaust end of cylinder I, and tube 'I supported solely by the apertured disks 9 communicates at opposite ends with the respective flow reversing chambers I0 and II. Disks S are preferably of imperforate metal except where provided with openings for the tubes 6, I and 0. Three longitudinally extending fins I2, I3 and I4 radiating from the axial center of cylinder I to the outer walls thereof, divide the latter into three longitudinal compartments I5, I6 and I'I, each of which accommodates one of the tubes. These compartments are packed with sound absorbing material such as used in the end spaces 4, which material occupies the space around the perforated tubes and completely nlls each compartment. The ns are welded or otherwise suitably secured at their ends to the disks 9 and at their longitudinal edges to the inner face or wall of the cylinder I. Fins I3 and I4 are perforated while fin I2 is of solid metal for reasons which will be presently explained. That portion of the tub-e 6 which passes through reversing chamber II at the front or inlet end of cylinder I, as well as that part of tube 8 which passes through reversing chamber I0 at the rear or exhaust end of the cylinder are solid, that is the perorations formed in the remainder of these tubes are omitted.

Exhaust gases flow through tube 6, into reverse flow chamber I0 thence back through tube l to reverse flow chamber II and finally into and through tube 8 to the atmosphere. This flow is possible because tubes B and l8, in which the iiow of gas is in the same direction, are separated from each other against direct communication by solid fin I2, whereas tube 'I Ihas direct communication with the tubes 6 and 8 through the periorated ns I3 and I4 respectively.

The use of the perforated dividing iins is a most important feature of my invention. If these fins were solid, it would be necessary to make the diameter of the cylinder I much larger in order to provide compartments I5, I6 and Il large enough for the efficient absorption of sound in the sound absorbing material packed therein. However, by virtue of these perforated iins, the impulses in the gas stream passing through any one tube are not confined to the compartment housing thattube but to the contrary are free to expand through the perforations in the fins directly into the next adjacent tube in which the flow of gases is in the opposite direction. Thus impulses in the stream of exhaust gases flow through tubes 6 and 8 in the same direction, that is from the tic structure.

front to the rear of the mullier, are not free to merge directly with each other, but onlyindirectly through tube 1, whereas the impulses in the stream of gases flowing through tube l in a direction opposite to that of the flow through tubes 6 and 8, are free to merge with the latter, and vice versa. It will be noted that the gas flow in the tubes separated by the perforated fins I3 and I4 is opposite in direction in each case. This makes it possible for the high impulses in one gas stream to expand through the perforated n into and merge with the low impulses of the gas stream passing through the adjacent tube on the opposite side of this fin, and this merging of the high and low impulses is constantly taking place throughout the entire muffler. Furthermore, as the gas streams are flowing in opposite directions the merging action is greatly multiplied and consequently an extremely high degree of muiiling efficiency is attained in a muiller of very short length.

Due-to the fact that the direction of ow of gases passing through tubes 6 and 8 is the same in each tube, and because the shearing or merging action previously referred to could not take place under such conditions, an imperforate n is employed to separate thesetubes from each other. If the n I2 were perforated as in the case of ns I3 and I4, the merging efficiency between tubes 6 'and 8 would be no greater than that of a conventional straight stream acoustic mufler, because in the relatively small muffler practicable with my invention any muiiing effect thus attained would be neutralized by the short cut part of the gases would take from tube 6 to tube 8. However, if the dimensions of the muffler are increased any appreciable extent beyond the extrememinimum which it is possible to employ according to my invention, n I2 may be perforated to advantage. As a matter of fact even where n I2 is solid or imperforate as illustrated herein, an indirect merging of impulses between tubes 6 and 8 and their compartments takes place through the compartment I6 in which tube I is located.

The acoustic material between disks 3 and end walls 2 has a material effect on muflling efliciency and acts favorably upon the gas stream as it expands in the reversing chambers-I and II. However, as previously stated, the disks 3 and 4 the packing between these disks and the end walls 2may be omittedwithout any noticeable effect with many engines now on the market, particularly with eight `or twelve cylinder engines.

The action of the gases previously described, that is the expansion of the high gas impulses in one chamber into the low areas in the adjoining chamber'and vice versa, provides the necessary expansion for efficient muflling in a muiller in which the chambers are much smaller than would be necessary in a conventional acous- VIt also materially reduces back pressure. Experiments with reverse stream mufflers having non perforating dividing fins show that there is a very material increase in back pressure, as compared to that of straight stream muiilers of the same capacity, due to the fact that the entire gas stream is completely reversed two times in the former structure, Whereas according to my invention there is a progressive transfer of exhaust gases from the compartment l as large.

I enclosing tube 6 to the compartment I 6 of tube 1, and thence on into compartment I 'I of tube 8. 'Ihis transfer action more than comperisates for or neutralizes the increase in back pressure set up by the two reversals of the main stream. 'Ihus the part of the gas stream going through the reversing chambers I0 and II is approximately one half that which would pass through a reverse stream muiiler of the nonperforated fln type, and consequentlythe action is equivalent to that obtained with a conventional muffler having an expansion chamber two times This progressive transfer or merging of impulses also results in a highly efficient scavenging action, as the gases are not trapped inside the outer wall as is the case in muiilers of conventional acoustic structure, but are constantly passing along the inner circumference of the shell from one chamber to the next so that the entire muier becomes hot and is maintained at a temperature above the condensation point, even in cold weather and under conditions of intermittent and slow driving.

'I'he modified form of the invention shown in Figures 4, 5 and 6 functions in substantially the same manner as the preferred form just described. In this modification the gas passage or tube 'I ofthe preferred form is eliminated and the reverse gas passage 20 is formed by two spaced parallel dividing fins or plates 2I and 2| of a Width equal to the diameter of shell I and which extends from one plate 9 to the other plate 9. The outer end of plate 2| is perforated as at 22 and the inner end of plate 2l is perforated as at 23. y The exhaust gases flow outwardly or rearwardly through tube 6 thence into reverse chamber I0 and back through passage 23 to and through reverse chamber II into and forwardly through tube 8. It will thus be seen that communication between tubes 6 and 8 can be had only indirectly through passage 20.

Having thus described my invention, what I claim is:

A reverse stream muffler comprising an imperforate shell having end walls, plates spaced from the end walls to form reversing chambers, a, perforated tube extending between said plates and communicating at opposite ends with said reversing chambers, a pair of gas communicating tubes, one of said tubes communicating at one end with one of said chambers and at its other end extending into and through the other of said reversing chambers and its end wall, and the other of said tubes communicating at one end with said last chamber and extending at its other end into and through said first chamber and its end wall, the portions o-f'the tubes extending through the said reversing chambers being solid and the portions extending between the said plates being perforated, a plurality of fins radiating from the axis of said shell extending between said plates and forming walls between said tubes, said ns subdividing said shell into three compartments one for said perforated tube and one each for said gas tubes, the fin separating said gas tubes being solid and the fins between the perforated tube and the gas tubes being perforated, and a packing of foraminous material substantially filling said compartments.

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