US3029896A - Muffler structure with baffle means - Google Patents

Description

April 17, 1962 G. A. LYON MUFFLER STRUCTURE WITH BAFFLE MEANS 3 Sheets-Sheet 1 Filed March 24, 1958 ZZTVEZ'YZUF I Ggorye fl/erf Lyon April 17, 1962.

3 Sheets-Sheet 2 Filed March 24, 1958 hZ EHZUF Georye fl/ber/ Lyon fig a a I E/[575.

A ril 17, 1962 G. A. LYON 3,029,896

MUFFLER STRUCTURE WITH BAFFLE MEANS Filed March 24, 1958 3 Sheets-Sheet 3 United States PatentO 3 029 896 MUFFLER STRUCTURE WITH BAFFLE MEANS George Albert Lyon, Detroit, Mich., assignor to Lyon Incorporated, Detroit, Mich., a corporation of Delaware 7 Filed Mar. 24, 1958, Ser. No. 723,391 10 Claims. '(Cl. 181-57) Among the problems encountered are the increasing need for more elficient muflling due to increasing density of populations and rising vehicle congestion, while at the same time compression ratios and power of the engines has been increased. The current trend toward lower chassis and more complex bracing and frame structure further accentuates the problem. For improved power, the motor fuels are provided with additives which increase the corrosive effects of exhaust residues in the presence of moisture especially where only short runs are made so that condensate can accumulate because the exhaust system does not heat sulficiently to dry out.

The principal direction muffler designs have more recently taken is toward increasingly complex reverse flow types of muffler structures of considerable length and transverse dimensions and involving somany pants and so much material as to encourage the use of the most inexpensive material, generally sofit, untreated cold rolled steel, highly susceptible to corrosion and thus early failure of the mufilers. I

It is, accordingly, an important object of the present invention to provide improvements in mufiler structures adapting the same to be made in relatively small sizes but with unusually large sound damping, mufiling capacity.

Another object of the invention is to provide an improved mufiler structure lending itself readily to simple construction and enabling substantial standardization of various pants to reduce the number of manufacturing operations.

A further object of the invention is to provide an improved mufiler structure which may be selectively provided in various mufiling capacities by the addition or subtraction of substantially standardized components in effecting assembly for various known requirements.

Still another object of the invention is to provide an improved mufiler structure affording "a highly eflicient flow pattern minimizing accumulations of condensate or corrosive residues within the muffler.

Yet another object of the invention is to provide an improved self cleaning mufiler construction.

It is also an object of the invention to provide improved muffler structure which because of economical construction encourages the use of higher grade, more corrosion resistant materials.

A yet further object of the invention is to provide an "ice FIGURE 2 is a sectional elevational view taken substantially on the line II- II of FIGURE 1;

FIGURE 3 is an end elevational view of a slightly modified form of the muffler;

FIGURE 4 is aside elevational view, partially in longitudinal section of a modified form of the mufi ler;

FIGURE 5 is a sectional elevationalview taken substantially on the line V'V of FIGURE 4;

FIGURE 6 is an exploded assembly view of the mufiler of FIGURES 4 and 5;

FIGURE 7 is a side elevational view, partially in longitudinal section of a further modification of the mufiier; and

FIGURE 8 is a top plan view of one of the casingbaffle sections of the mufiler of FIGURE 7.

According to'the present invention, mufiling of pressurized flowing gases and especially such as produced by internal combustion engines is accomplished by repeatedly breaking or sub-dividing the gas stream into a large number of small more or less jet streams directed into headon collision with one another in restricted chamber space under slight back pressure and then controlled onward movement. Especially where the gas stream is impelled with explosive, pulsating, percussive force, the head-on impingement of the gas stream subdivisions has a beneficial impulse cancelling, neutralizing effect until such a low pitch is attained as to be below an objectionable noise level, attaining substantial imperceptibility within the usual hearing range. In accomplishing this, the gases are conveyed in one general direction away from the source without any necessity for reversal of movement improved muffler construction having novel cooling axially of the flow path, any deviations from a continuous axial flow being across the general flow axis and of lim-' .ited extent and purposeful effect.

In one form of the invention as shown in FIGURES l and 2, the invention is embodied in a muffler unit 10 of suitable length and diameter and providing a housing having therein a tortuous, step-by-step forwardly advancing, sound muflling flow path for the gas stream. In the present instance the mufller 10 comprises a telescopically internested series of individual elements enabling ready variability as to muflier length and sound damping capacity to meet various practical requirements and for this purpose comprises a tubular end member 11, a series of muflliug b aille members 12, a terminal b afile member 13 and associated therewith an end closure member 14.

In the present instance, the end member 11 includes a central inlet projection 15 adapted to be connected to an exhaust duct from the engine of a vehicle or other internal combustion engine. The inlet projection 15 is of substantially smaller diameter than the principal diameter of the end cap member 11, and a flaring shoulder 17, preferably corrugated for strength connects the inlet with the tubular body of the member 11.

Each of the baflle member sections 12 is preferably of substantially cup shape and of substantially the same diameter as the diameter of the end member 11 which is provided with an enlarged diameter portion 18 adjacent to its free end internally dimensioned to substantially the outside diameter of the baffle members 12 so that the first in the series of baille members can be telescopically nested into the enlarged diameter portion 18 which is provided at juncture with the main tubular body of the member 11 with an offsetting stop shoulder 19 against which the shoulder of the bafile member bottoms in assembly to determine the coaxial, operative relationship to the end member 11. Each of the bafile members 12, in turn, is provided in the axial wall thereof with a similar larger diameter portion 20 provided with an offsetting juncture shoulder 21. against which the next of the bafile members 12 in the series bottoms in telescopically nested assembled relation with the upstream companion baflle member. In

3 the assembled generally stacked, telescopically internested relationship, the baffle members and the end member are preferably fixedly secured together as by means of welding or other suitable securing means to prevent separation under operating conditions. I

As a cooling expedient, the free end portions of the end member 11 and the baffie members 12 are preferably of an enlarged heat transfer, shield skirt form as identified at 22 in each instance connected to the enlarged diameter assembly seat portionlS and 2-0, respectively, by a flaring forwardly and radially outwardly angled shoulder 23, while an annular out turned reinforcing and riffle bead terminal 24 provides a finishing edge for the free extremity of the skirt. Through this arrangement, improved heat transfer to the slip stream air is attained while the substantial dead air spaces in the chambers afforded between the skirts 22 and the adjacent bafile walls have an insulating effect against undue heat radiation, especially where the mufller is mounted under a metal floor deck of a vehicle.

For sound muffling control, each of the baflie members 12 is provided with a baflle wall portion 25 which is disposed in completely blocking relation across the inside of the chamber within the composite housing afforded by the assembly. Means are provided on each of the baffle walls 25 for dividing the exhaust gas stream into a plurality of uniform series of air streams or jets directed into sound damping, head-on impingement. To this end, the baffle wall 25 in each instance includes one or more, in the present instance shown as two, corrugation-like axially rearwardly projecting continuous annular hollow rib formations 27 each of which provides a groove chamher opening forwardly therefrom. In the opposing genthe directional flow arrows at the right-hand end of FIG- URE 1 wherein it will be seen that the exhaust gas stream entering the muffler through the inlet 15 tends to expand laterally toward the perimeter of the chamber provided between the end member shoulder wall 17 and the margin of the first of the baflle walls 25 and then is subdivided and flows into the opposing series of orifices 28 in the baffle ribs 27. The aggregate flow area afforded by the orifices 28 is such as to provide only slight pressure drop and thus only slight back pressure on the exhaust stream.

After the initial head-on jet collision reaction and thus substantial sound mufiling, the exhaust gases move forwardly from the baflle rib groove chambers under controlled, muffling conditions, herein effected by an auxiliary baffle disk 29 secured to the forward side of the margin of the baflle wall 25 and sloping forwardly and inwardly toward the axis of the muffler in diverging relation to the baflle Wall 2-5 and in predetermined spaced relation to the mouth of the respective baffle rib groove chambers so as to direct exhaust gas flow therefrom toward a central opening 30 in the auxiliary baille. As a result, the exhaust gases issue from the opening 30 into the limited chamber space between the adjacent baffles 12 in a more or less swirling stream having a desirable mufiiing effect as the gases move on to become again sub-divided by the series of orifices '28 in the next suceeding battle and repeat the mufiling cycle. As the cycle is repeated again I trol, collision-jet batfle members 12 in a manner to facili- 1 tate not only initial assembly, but securement in the muffler unit. To this end, each of the auxiliary or secondary mufiier members 29* is provided with a peripheral generally axially extending flange 31 dimensioned for slidable, preferably press fit engagement within the tubular wall of the associated balfle member 12, and with the corner junctures of the flanges 3 1 with the body portions of the bafile members 29 nested or bottomed in the reentrant corner defined between the tubular and baflle walls of the baffle member 12. This properly orients the secondary baflie members 29 within the bafile members 12, and also I disposes the flanges 31 of the secondary baflle menbers substantially coextensive with the offset encompassing seatportions 20 of the member into which each of the respective baflie members 12 is telescopically engaged so that, especially where welding is employed to secure the members together, all three internested components in each instance can be and are secured together in a single welding operation.

By the particular construction of the bafile wall portions of the baflle members 12, suflicient limited axial resilient flexing or yielding is permitted to avoid undue strain in the event of back fire of the engine. Nevertheless, although the concentric jet orifice ribs 27 enhance the resilience of the baflie walls they also assure lack of resonant response to the exhaust gas pulsations but actually act as sound dampers. Not only resistance to deformation but also further enhanced sound deadening is accomplished by having central concave convex portions 32 on the respective baflie wall portions of the baflle members 12.

At the exit end of the muffler unit 10, the terminal baflle member 13 which in other respectsmay be substantially the same as the'baffle members 12 is formed in this instance with a straight tubular free terminal end portion within which an axially extending marginal flange 33' on the end closure member 14 is telescopically en gaged and secured. As shown, the end closure member is in the form of a generally funnel-shaped structure tapercollision, swirling stages of mufller treatment, gradually.

freer flow, slow down is effected. Although in the relatively cold state of the muflier and slow speed operation of the engine there may be substantial cooling of the exhaust gases from the inlet to the outlet ends of the muffler and thus inherent slow down due to contraction of the gases by cooling, in the high speed operation of the engine and after the mufller has become heated to the point where contraction of the gases is only a minor factor, a gradual increase in the aggregate crosssectional flow area of the jet producing apertures 28 in the successive baifle plates affords the gradual reduction in pressure drop and thus slow down of the gases and freer flow as the sound producing vibrations and impulses of the gases are gradually dissipated *and the noise level curve moves nearer to the flat sound free condition. Increase in the aggregate flow area may be accomplished by an increasing number of the same size holes, but is shown as conveniently resulting from gradually larger size holes of the, same number in each series of the jet producing apertures 28 in each successive battle p ate.

Although the cross-sectional form of the muffler 10 in FIGURES 1 and 2 has been shown as circular, as may generally be permitted in view of the small size of the muffler, where head room or other conditions require, the mufiler may be of the oval shape of the muffler 35 in FIGURE 3 with respect to cross-section, but in other respects may be substantially the same as the muffler 10 or the other forms of the mutfler to be hereinafter described. s a

In FIGURES 4. 5 and 6 a modified mufller structure 37 is shown which in general respects is similar to the mufiler 10. To this end the mufiler 37 includes a forward end tubular section 38 having an inlet extension 38a and a flaring shouldered structure leading to a tubular wall that telescopically receives .therein and is suitably secured fixedly about a complementary diameter tubular, generally cup shaped first vbaffie member 39 in a series of such baffle members which in turn has telescopically fitted there-into the next succeeding baffle member 39, and so on throughout a substantialseries of the baffle members depending on the number required for any given preference 'or muffling or silencing condition. Each of the muffler members 39 has intermediately in the axial tubular wall thereof a shoulder 40 which faces generally axially rearwardly and receives in locating relation the edge of the member .telescoped thereabout on its outer side and also or alternatively the next succeeding telescoped inner-end shoulder of the associated bafile member. At its exhaust end, the muffler 37 includes an exhaust closure nozzle member 41 having an axially 'extending marginal flange .42 secured telescopically within the last in the series of the baffle members 39 and of gen erally tapered nozzle structure with a tubular exhaust extension 43.

, Each of the baffle members 39 is provided with a bathe Wall 44 that extends in closing relation across thechamber defined within the muffler 37 and has adjacent its margin a rearwardly projecting continuous rib 45 defining a forwardly opening chamber and having in the opposed side walls thereof opposing circumferential series of jet producing apertures 47. Thereby the exhaust gases advancing forwardly through the mufller 37 are divided'adjacent to the perimeter of the baflle member 39 in each instance into a large number of opposing, colliding jets within the chamber defined by the respective gas sub-dividing, collision jet producing rib 45. Attached to a rearwardly convex and forwardly concave central wall portion 48 of the baffle member is a control auxiliary baffle plate 49 which may be of complementary concave convex form and with the margin thereof extending generally radially outwardly and axially forwardly across the mouth of the jet rib chamber, affording a gap with the radially outer margin defining the chamber mouth to divert the gases under controlled conditions toward the perimeter of the chamber defined between the forward side of the baffle wall 44 and the next forward bafile wall44 In so issuing the exhaust gases assume a generally whirling action and are then compelled to move generally radially inwardly toward the center of the mufiler and are again sub-divided into a series of jets by the jet aperture orifices 47 of the next succeeding bafile member for repeated head-on jet collision and thus impulse, sound wave cancelling reaction. Each succeeding series of orifices 47 may be of at least slightly greater aggregate cross-sectional flow area to accomplish gradually slower and freer movement of the gases as the sound producing factors in the gases are gradually eliminated or at least subdued.

In FIGURE 6 is shown how assembly is adapted to be effected by telescopic series assembly insertion of one baffle member into the other.

In the modification of FIGURES 7 and 8, a somewhat simpler, highly effective muffler 50 is disclosed including an inlet end closure portion 51, a series of muffling baffles 52 and an end closure funnel nozzle member 53. Similarly as in the other forms of the muffler disclosed, the inlet'member 51 has an inlet opening extension 54 from which a flaring shoulder leads to the full diameter tubular wall of the inlet member telescopically engaged about the tubular wall of the first of the baflle members 52 in the series which is provided intermediately with an offset shoulder 55 by which the relative axial disposition of the members is determined in assembly.

In this instance each of the baffle members 52 has a baffle wall 57 provided with a continuous forwardly projecting rib 58 having slightly divergent axial walls provided with multiple series of jet orifice apertures 59 in each instance, and with the respective series in each wall matching and opposing one another in the opposite walls so as to produce respective jets in head-on collision within the chamber defined by the orifice rib 58. By the plurality of axially progressive series herein shown as three in each wall of the orifice rib not only is the exhaust stream sub-divided into opposing jets which collide head-on in the rib chamber but upon spreading out after collision the jets commingle in a generally turbulent relationship which further acts to subdue sound producing pulsations.

In the mufiler 50, the jet ribs of the succeeding bafiles 52 are disposed with respect t-othe immediately preceding bafile wall 57 to control, and divide the exhaust gases issuing from the mouth of the rib chamber .of the immediately preceding bafile wall into divergent stream portions flowing into the between baffie chamber for resubdivision into jets within the next succeeding baflle rib for the next stage of headron jet collision sound impulse or wave reduction and mufiling. This eliminates the need for a separate or secondary control baffle structure. By having the respective baffie members coaxially located in predetermined axial disposition by means of the shoulders 55, location of the crown or ridge portions of the respective succeeding jet bafile ridges 58 in proper controlling relation to the mouths of the respective rib chambers is facilitated.

Ifpreferred, of course, the jet orifices 59 in the respective succeeding batlles may be of progressively increasing aggregate cross-sectional flow area, but as shown all of vthe orifices are of the same size in view of the fact that there are a substantially greater number of the jet orifices in each of the bafile ribs to begin with.

Inasmuch as the central portion of the baffle wall 57 in each instance is of substantial diameter, it has been found advantageous to have, the same of rearwardly concave and forwardly convex shape as shown, thereby cffectively avoiding any diaphragm resonance and any tendency to buckle under back fire since the direction of concavity is in the direction of movement of any sudden surge of exhaust or products of combustion gases that may pass through or originate in the mufiler in a back fire. Nevertheless, there is a desirable resilient cushioning deflectability in the bafile walls 57.

In order to provide for efficient blowing through of condensate, soot, lead or other residues or other contaminants, the marginal portions of the bafile walls 57 radially outwardly from the jet ribs 58 are preferably provided with blow through holes 60 in suitable series, of small size and spaced preferably circumferentially a suitable distance, although if it is known which portion of the muffler will be down in the operating system, one or more of the blow holes 60 may be provided only on the down side of the baffle wall. Since the blow through holes 60 A are of substantially smaller aggregate cross-sectional flow area in each instance than the cross-sectional flow area afforded by the collision jets 59, only a minor proportion of the exhaust gases will blow therethrough and will come into turbulent interference with the gases that issue from the respective associated jet ridge chamber in each instance, so that there is little likelihood of any of the ex- I nozzle 53 has an axially extending marginal flange 61 which is telescopically secured within the end of the endfor forming the desired shapes.

most of the baffles 52 and is provided with a generally funnel-shaped structure terminating in a tubular exhaust nozzle extension 62 which if preferred may, as shown, be slightly smaller diameter than the inlet 54 for the purpose of minimizing back fire.

Any of the mufflers may be made from suitable sheet material such as stainless steel, aluminized steel, aluminum alloy, or suitable heat and corrosion resistant moldable plastic material having a satisfactory cost factor. Sheet metal has presently the advantage of economical base cost and mass production manufacturing techniques In view of the rugged construction of the several components, fairly thin sheet material may be used. By the use of higher grade materials greatly increased mufller life can be attained.

' In all forms of the invention, the high muflling efficiency attained enables the use of small sizes of the mufflers with nevertheless high efficiency rating. Because of the sectional assembly of the baffles, mufllers of vary- .ing capacity can easily be assembled to suit various requirements. For example, in association with a vehicle engine that has a dual exhaust system, two mufflers of medium size may be used in each of the dual portions of the exhaust system. On the other hand if preferred, a plurality of mufllers and silencers all made up from appropriate numbers of mufiler baflle sections may be used, the silencers having smaller numbers of sections than the mufller units. In other words, a high degree of flexibility for desired results is attainable by virtue of the telescopically related sectional construction of the mufilers.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a mufller structure, means defining a muflle chamber havingan inletand an outlet, a control baflle across the mufile chamber having formed therein and projecting toward the inlet a jet producing hollow grooved rib having opposed generally axially extending substantially parallel adjacently spaced wall portions with opposed orifices therein through which fluid to be mufiled coming from the inlet must pass in the form of opposed jets to collide head-on within the groove defined by the rib, said rib groove opening toward the outlet, and a fluid controlling baffle member disposed at the mouth of said rib groove 'and'operative to divert the fluid issuing from said rib groove laterally within the muflie chamber.

2. In a mufiler structure, means defining a muflle chamber having an inlet and an outlet, a control baffle across'the muflle chamber having formed therein and projecting toward the inlet a jet producing hollow grooved "rib having opposed generally axially extending substantially parallel adjacently spaced wall portions with opposed orifices therein through which fluid to be mufiled coming from the inlet must pass in the form of opposed jets to collide, head-on within the groove defined by the rib, said rib groove opening toward the outlet, and a fluid controlling bafi'le member disposed at the mouth of said rib groove and operative to divert the fluid issuing from said rib groove laterally within the muflle chamber, said bafile member comprising a disk attached to said control baflie on the downstream side thereof.

3. In a mufller structure including means defining a muffle chamber having inlet and outlet ends and a plurality of baflles transversely across the muflle chamber,

bafi e having a ridge that is associated with the mouth 8 of the rib groove channel of said next adjecent bathe to control flow of the fluid therefrom. v

4. In a mufller construction including means defining a muffle chamber having an inlet and an outlet and a baflle across the mufiie chamber provided witha plurality of concentric ring ribs therein projecting toward the inlet and each having a series of orifices in the opposite walls thereof through which fluid passing from the inlet toward the outlet is sub-divided into a plurality of jet streams that collide head-on within the chambers defined by the respective ribs, the rib chambers opening toward the outlet.

5. In a muffler construction including means defining a muflle chamber having an inlet and an outlet and a baffle across the muflie chamber provided with a plurality of concentric ring ribs therein projecting toward the inlet and each having a series of orifices in the opposite walls thereof through which fluid passing from the inlet toward theoutlet is sub-divided into a plurality of jet streams that collide head-on within the chambers defined by the respective ribs, the rib chambers opening toward the outlet, and means extending generally across the openings from the ring rib chambers for deflecting the fluid issuing therefrom laterally within the muflle chamber.

6. In a muffler structure, a plurality of coaxially aligned and connected sections providing fluid controlling muffling baflles within a muffle chamber defined by the sections in assembly, each of said sections having a tubular terminal portion of substantial length and enlarged diameter providing a spaced dead air insulating and heat dissipating skirt disposed to project axially about the next adjacent of the sections and externally of the muflle chamber.

7. In a mufiler structure including means defining a muflle chamber having an inlet at one end and an outlet at the opposite end, said chamber having fixedly thereacross and in spaced relation a plurality of baffle walls defining therebetween expansion spaces, each of said walls having a corrugation-like rib projecting generally toward the inlet end and in each instance defining anarrow channel opening toward the outlet end, said ribs being defined by confronting walls, said walls having respective jet-forming series of orifices therein generally aligned with the jet orifices of the confronting wall in each instance so that fluid to be muffled entering the chamber through the inlet end is forced to pass through said jet orifices and provides jets of the fluid which collide headon with the jets from the respective opposed orifices within the respective rib channels before moving out of said channels into the expansion space into which the channel opens, the height of the ribs being such that the crests of the ribs on the baflle walls downstream project closely toward the openings from the rib channels of the immediately adjacent upstream bafile wall to thereby serve as deflectors forcing the fluid issuing from the channels to move laterally toward each side of the ribs thus serving as deflectors.

8. In a muffler structure including means defining a muflle chamber having an inlet at one end and an outlet at the opposite end, said chamber having fixedly there across and in spaced relation a plurality of baflle Walls defining therebetween expansion spaces, each of said walls having a corrugation-like rib projecting generally,

toward the inlet end and in each instance defining a narrow channel opening toward the outlet end, said ribs being defined by confronting walls, said walls having respective jet-forming series of orifices therein generally aligned with the jet orifices of the confronting wall in each instance so that fluid to be muffled entering the chamber through the inlet end is forced to pass through said jet orifices and provides jets of the fluid which collide head-on with the jets from the respective opposed orifices within the respective rib channels before moving out of said channels into the expansion space into which the channel opens, the baflle walls having attached theredefining therebetween expansion spaces, each of said walls having a corrugation-like rib projecting generally toward the inlet end and in each instance defining a narrow channel opening toward the outlet end, said ribs being defined by confronting walls, said Walls having respective jet-forming series of orifices therein generally aligned with the jet orifices of the confronting wall in each instance so that fluid to be muflied entering the chamber through the inlet end is forced to pass through said jet orifices and provides jets of the fluid which collide head-on with the jets from the respective opposed orifices within the respective rib channels before moving out of said channels into the expansion space into which the channel opens, the baffle walls having attached thereto on the downstream side thereof respective auxiliary diversionary baflie plate disks extending obliquely adjacent to the openings from the rib channels of the baflle Walls to.

which attached for diverting the fluid issuing from the channels laterally within the respective expansion chambers, said baffle plate disks being attached to the outer margins of the baflie walls and having central apertures toward which the baflle plate disks are obliquely inclined.

10. In a muflier structure including means defining a muflie chamber having an inlet at one end and an outlet at the opposite end, said chamber having fixedly thereacross and in spaced relation a plurality of bafiie walls defining therebetween expansion spaces, each of said walls having a corrugation-like rib projecting generally toward the. inlet end and in each instance defining a narrow channel opening toward the outlet end, said ribs being i so that fluid to be mufiied entering the chamber through the inlet end is forced to pass through said jet orifices and provides jets of the fluid which collide head-on with the jets from the respective opposed orifices within the respective rib channels before moving out of said channels into the expansion space into which the channel opens, the baffle walls having attached thereto on the downstream side thereof respective auxiliary diversionary bafile plate disks extending obliquely adjacent to the openings from the rib channels of the baflle walls to which attached for diverting the fluid issuing from the channels laterally within the respective expansion chambers, said baffle plate disks being attached to the central portions of the baflle walls and having outer marginal portions which are obliquely inclined toward the perimeter of the muffle chamber.

References Cited in the file of this patent UNITED STATES PATENTS 779,024 Buchner et a1 Jan. 3, 1905 1,087,397 Persson Feb. 17, 1914 1,607,146 Bauroth Nov. 16, 1926 1,671,829 Ledwinka May 29, 1928 1,741,078 Scarritt Dec. 24, 1929 2,084,435 Deremer June 22, 1937 2,151,084 Deremer Mar. 21, 1939 2,360,429 Leadbetter Oct. 17, 1944 2,576,522 Kyifin Nov. 27, 1951 2,761,525 Moss Sept. 4, 1956 FOREIGN PATENTS 9,335 Great Britain 1911 282,875 Great Britain Dec. 28, 1927 816,639 France May 3, 1937

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