US 2552615 A
Description (OCR text may contain errors)
y 15, 1951 L. F. BALTZER 2,552,615
MUFFLER WITH SPIRAL CONICAL INSERT Filed May 29, 1948 2 Sheets-Sheet l Inventor F BALTZER Attorney.
y 1951 L. F. sA'L'rzER 2,552,615
MUFFLER WITH SPIRAL CONICAL INSERT Filed May 29, 1948 2 Sheets-Sheet 2 Inventor LAWRENCE F BALTZER by I Patented May 15, 1951 MUFFLER WITH SPIRAL CONICAL INSERT Lawrence F. Baltzer, Berwick, Nova Scotia, Canada Application May 29, 1948, Serial No. 29,969
This invention relates to improvements in a muffler with spiral conical insert for automobile engines and the like and appertains particularly to a silencing device to mufiie or deaden the noise of the exhaust gases of internal combustion motors by smoothing out the sharp intermittent impulses.
An object of the invention is to provide a muffler casing with a spiral roll, preferably formed of a corrugated ribbon and displaced longitudinally into a cone, filling the casing for the full diameter thereof to provide a maximum of longitudinally extending passages and surfaces to cause a frictional flow-retarding influence on the contacting and immediately adjacent portions of the current of gases and by thus setting up a differ ential in the speed of flow, as between the portion of gases actually or nearly contacting the surfaces and that portion midway between the flow-slowing surfaces, stretch out the sharp reports into a smooth, evenly flowing, quiet stream.
A further object of the invention is to provide an exhaust mufi'ler with ample cross sectional area and wherein the insert affords direct longitudinal passage from inlet to outlet so that though the flow impulses are evened out no back pressure ever develops.
A still further object of the invention is to provide a mufiier of the nature and for the purposes specified that is characterized by structural simplicity, durability and efficiency and being capable of manufacture at reasonable cost is thereb rendered commercially desirable.
To the accomplishment of these and related objects as shall become apparent as the description proceeds, the invention resides in the construction, combination and arrangement of parts as shall be hereinafter more fully described, illustrated in the accompanying drawings, and pointed out in the claims hereunto appended.
The invention will be best understood and can be more clearly described when reference is had to the drawings forming a part of this disclosure wherein like characters indicate like parts throughout the several views.
In the drawings:
Figure 1 is a longitudinal section through a mufiier casing showing my improved silencing elements arranged therein;
Figure 2 is a similar sectional view showing a modified arrangement of the silencing elements;
Figure 3 is another such sectional view with a further modified form of silencing insert;
Figure 4 is an enlarged cross-section of a muffier casing with a spirally rolled metal ribbon insert in elevation; and
Figures 5 and 6 are perspective views of alternative forms of metal ribbon with the corrugations thereof extending diagonally and transversely respectively; and
Figure '7 is a perspective of another insert.
In carrying out this invention I have found a simple and economical way to form a flow equalizing and silencing insert for a muffler shell is to roll a narrow strip or ribbon of metal into a reasonably tight spiral with a diameter substantially equal to the interior of the casing so as to fit snugly therein. Four such spiral rolls I will be seen in an elongated cylindrical muffler shell or casing 2 with inlet and outlet openings 3 and 4 at opposite ends thereof, in the form shown in Figure 1. The diameter of the shell should be not less than approximately three times that of the ports.
The spiral ribbon silencing inserts i may be of smooth material but I prefer to form them of corrugated metal strip 5, with the corrugations running diagonally or at an angle to the length of ribbon as seen in Figure 5 or transversely as seen in Figure 6.
An effective treatment of these closely wound spirals I is to displace the center of the coil longitudinally, pulling the roll out into cone shape as in Figures 1 and 2. These cones can then be arranged in many ways, e. g., in pairs as in Figure l, with the apex of one nesting within the base of the other, one such pair in each end of the casing and the apexes of the inner or center most cone of each pair nearly meeting midway of the muffler casing; in Figure 2, a nesged pair of cones I are located about the center of the casing, both facing with their apexes to the outlet and illustrated to indicate the corrugations 5 on the ribbon of the cone to the right as diagonal and the other transverse; and a very simple form appears in Figure 3 where the silencer insert I is a closely wound spiral roll of a substantially wider corrugated ribbon, that is not distorted into conical for-m.
Normally the spiral roll of corrugated metal ribbon is wound tightly enough that it will not rattle or vibrate and no extraneous fasteners or supports are necessary. However, when a plain metal strip is used or a more openly wound spiral is desired in the roll, a spreader may be used such as the diametrical bar 6, appearing in Figure 4, with spacing teeth 1 extendin between adjacent convolutions of the spiral coil or the teeth may be integral lugs out-struck from the coil material itself to be self spacing even 3 as the corrugations of the preferred ribbon material.
Following is the theory advanced for the effective sound muflling action of this device: As the stream of exhaust gases enter the muffler by the inlet 3, the intermittent and spaced high pressure spots in the flow on expanding to occupy the greater space afforded tend to be reduced in intensity and when thus thinned down pass through the multitude of small common direction establishing passages in the coiled ribbon cone improving uniformity of pressure and flow over the cross-sectional area of the muffier. Here too the sum-total extent of the passage area surface stretches out the pressure spots further with the accompanying levelling influence. In a set-up as shown in Figure 1 where the stream of exhaust gases is subjected to this treatment on four successive occasions in its passage through the muffler and still no appreciable back pressure developed because of the reasonably unimpeded direct-line flow, a satisfactory degree of silencing is obtained, the straight-through current keeps the inserts clean so they last longer giving top performance and there are no baffles to burn out or work loose and rattle.
The use of a coil of corrugated ribbon also breaks up the gas flow into a great many similar and parallel jets, each so small as to be almost inaudible and each subject to expansion on emerging from the passageway: Where the corrugations are diagonal, a multitude of tiny parallel and spiralling jets are set up that can be straightened out to parallel the axis of the muffler by a cone of transverse corrugated ribbon or made to spiral in the opposite direction by a reversed arrangement of the diagonal corrugations in a succeedingly placed ribbon cone insert.
From the foregoing description taken in connection with the accompanying drawings, it will be manifest that a muffler is provided that will fulfil all the necessary requirements of such a device, but as many changes could be made in the above description and many apparently widely different embodiments of the invention may be constructed within the scope of the appended claims, without departing from the spirit or scope thereof, it is intended that all matters contained in the said accompanying specification and drawings shall be interpreted as illustrative and not in a limitative or restrictive sense.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:
1. An exhaust muffler comprising a cylindrical casing with inlet and discharge openings at pposite ends and a transversely disposed closely wound spiral roll of metal ribbon of uniform width filling the interior diameter thereof, said roll being displaced longitudinally into conical form.
2. An exhaust mufiier comprising a cylindrical casing with inlet and discharge openings at opposite ends and a closely rolled spiral cone of corrugated metal ribbon filling the entire crosssectional area of said casing and providing a multitude of parallel, longitudinally extending passages of very small cross section.
3. An exhaust muffler comprising a cylindrical casing with inlet and discharge openings at opposite ends and a closely rolled spiral cone of corrugated metal ribbon filling the entire cross-sectional rear of said casing and providing a multitude of tiny passages and 0f considerable length affording a maximum of flow-paralleling area for a given distance without creating back pressure.
An exhaust muffler comprising a cylindrical casing with the usual inlet and discharge opening, and a tightly wound roll of corrugated ribbon of uniform width of a diameter to fit snugly in said cylinder disposed transversely therein between said openings, said corrugated ribbon roll providing a multitude of tiny parallel passages and being displaced longitudinally into conical form.
5. Ihe combination with the structure set forth in claim 4 wherein at least one o1 said corrugated ribbon rolls has the corrugations extending transversel of the length of ribbon.
6. The combination with the structure set forth in claim 4 wherein at least one of said corrugated ribbon rolls has the corrugations extending diagonally of the length of ribbon.
7. The combination with the structure set forth in claim 4 wherein at least two or more of said rolls are of conical form, the centre of the rolls being displaced longitudinally, and at least partially nested one within the other.
LAWRENCE F. BALTZER.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,685,701 Blanchard Sept. 25, 1928 1,897,649 Good Feb. 14, 1933 2,033,784 Pougher Mar. 10, 1936 2,075,316 Tyden Mar. 30, 1937 2,274,599 Freeman Feb. 24, 1942 FOREIGN PATENTS Number Country Date 1,332 Great Britain Nov. 6, 1913 89,289 Sweden May 19, 1937