US2764142A

US2764142A - Air cleaner and silencer assembly

Info

Publication number: US2764142A
Application number: US255817A
Authority: US
Inventors: Wesley W Mcmullen
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1951-11-10
Filing date: 1951-11-10
Publication date: 1956-09-25
Anticipated expiration: 1973-09-25
Also published as: DE1649046U

Description

Sept. 25, 1956 w. w. M MULLEN AIR CLEANER AND SILENCER ASSEMBLY Filed Nov. 1o.

2 Sheets-Sheet 1 AIR CLEANER AND SILENCER ASSEMBLY Filed NOV. 10, 1951 2 Sheets-Sheet 2 3nuentor 24 5/ wiry/e (Ittorneg United States Patent AIR CLEANER AND SILENCER ASSEMBLY Wesley W. McMullen, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 10, 1951, Serial No. 255,817 13 Claims. (Cl. 123-119) The present invention relates to an improved air cleaner and silencer assembly for an internal combustion engine. In general, the invention relates to an air cleaner and silencer assembly which may be combined with an engine in such a manner as to reduce the overall vertical displacement of the air cleaner-silencer assembly and the engine.

In one of its aspects, the present invention relates to an air cleaner and silencer assembly adapted to receive an operating element of an internal combustion engine.

In particular the invention relates to an air cleanersilencer assembly adapted to receive a carburetor float chamber therewithin.

The invention also relates to an air cleaner and silencer assembly adapted to receive a carburetor float chamber therewithin and which assembly is-adapted to be mounted directly on the carburetor inlet manifold.

The invention further relates to a structure in which an air cleaner unit may be assembled to a silencer unit and the assembly secured to a carburetor inlet manifold by means of a single fastening device.

In order to better understand the structure and operation of the present device, reference is made to the following specification wherein are described the preferred embodiments of my invention and which are illustrated in the following drawings.

In the drawings:

Figure 1 is a sectional view of an air cleaner and silencer assembly embodying my invention.

Figure 2 is a cross-sectional view taken substantially along line 2-2 of Figure 1 showing particularly the construction of the discharge outlet.

Figure 3 is a sectional view of another embodiment of my invention. 7 V

. Referring particularly to Figure 1 of the drawings, an air cleaner 10 and a silencer 11 are shown assembled to a carburetor inlet manifold 12. The silencer unit comprises a built-up annular structure which includes a vertical wall 13, the upper edge of which is formed into a flange 14 and the lower edge ofwhich extends inwardly and upwardly terminating in a downwardly opening U- shaped flange 15. Such a construction provides the silencer unit with an upwardly recessed lower face 16. A cylindrical member 17 is secured to flange and forms the inner wall of the silencer 11. Mounted upon wall 13 and secured to flange 14 is a cylindrical shell 18. The upper portion of shell 18 terminates in an inwardly inclined portion having an upstanding flange 19. Completing the silencer structure is upwardly opening dished member 20 which is adapted to be secured to flange 19 of the cylindrical shell 18 such that a wall portion 21 of said dished member extends above and an annular portion 22 extends below said flange. The annular portion 22 is designed to provide an oil sump as well as a vertical supporting base for the air cleaner 10 and is secured to cylindrical member 17 at a flange 22'. Annular portion 22 has a rather irregular profile including a ledge 23 and a stepped inner wall 24 which ice terminates in a second ledge 25 and flange 26 disposed interiorly of and spaced vertically from cylindrical member 17. A plurality of circularly disposed openings 17' are provided near the upper end of cylinder 17. The openings 17' provide silencer inlet openings through which the noise vibrations may pass into the silencing chamber.

The air cleaner unit 10 is also a fabricated annular structure and is adapted to seat within member 20 of the silencer. The air cleaner consists of a cylindrical wall 30 which terminates at its upper end in a flange 31 and the other end of which wall is formed inwardly and upwardly so as to define a bottom wall 32 ending in a flange portion 33. The bottom wall 32 is perforated so as to provide a plurality of air openings 34 therein. The inner wall of the air cleaner chamber is formed by a vertically disposed cylindrical member 35 secured to flange 33 and which member terminates at the upper end thereof in an outwardly projecting flange 36.

The annular cleaner chamber defined by

walls

30, 32 and 35 is filled with any well-known air cleaner filtering material 37 which is retained within said chamber by washer-like grid members 38 and 39.

In order to facilitate the flow of air from an annular air inlet chamber 29 defined by silencer wall 21 and cleaner wall 30 up through filtering material 37, a baffle member 40 is provided. Baffie 40 is an inverted dish shaped rim member having a downwardly stepped crosssection. The baifle is supported at one end only as a cantilever by said cleaner and which support is accomplished by clamping end 41 of said baffle within the juncture of bottom wall 32 and wall 35. When the air cleaner is seated within member 20 of the silencer, the free end 41 of the baflle is supported on circular ledge 23 of the silencer unit. The bafiie has a plurality of perforations 40 which permit oil to drain back to sump 22. Due to the flow of incoming air which creates a pressure in the sump the oil therein is forced up through holes A near end 41 of the baffle where it contacts the incoming air.

In providing the openings 34 in the bottom face 32 of the cleaning unit, depending members 42 are formed. The members 42 have numerous functions Within the cleaning unit one of which is to insure a fixed distance between the baffle 40 and the bottom face 32 of the cleaner unit so as not to vary the flow characteristics of the incoming air as would occur if said distance were to vary. Also, the depending members 42 in conjunction with baflie 40 and ledge 23 of the silencer unit support the outer portion of the air cleaner unit 10.

Air cleaner 10 is also supported on the silencer structure by circular ledge 25 of member 20. Covering ledge 25 is a gasket 43 on which the inner wall 35 of the air cleaner rests and by means of which gasket a substantially air tight juncture will ultimately be made.

Enclosing the air cleaner 10 is a circular cover 44 having an inwardly disposed raised annular portion 45 and a centrally positioned recess 46. Inside of the cover and secured thereto is a circular plate member 47 which overlies the annular portion 45 of the cover. A plurality of depending members are radially struck from the plate member 47 so as to provide air baffles 48. These baflles, as well as those depending from the bottom wall 32 of the air cleaner, reduce the tendency of air to flow circularly into and out of the air cleaner, thus diminishing the air turbulence and improving the flow characteristics of the air to the intake manifold.

Within the chamber defined by the annular portion 45 of the cover and plate member 47 is any suitable sound deadening material 49 such as felt.

An air discharge chamber 50 is defined by the inner wall 35 of the air cleaner and member 17 of the silencer. To further reduce the noise created by air flow through arca es the air cleaner and a subsequent carburetor, a hiss chamber 59 is provided at the upper end of the cleaner discharge passage 51 The hiss chamber is defined by a pair of spaced circular plates 52 and 53 which are secured to wall 35 of the discharge passage and which plates have concentric openings 5d and 55 formed centrally thereof. Therefore, the noise inherent in the operation of an air cleaner and carburetor assembly is absorbed first and mainly by the silencer chamber 11, then by the hiss chamber 50, next by sound deadening material 49 and finally by the filtering material 37.

As will be noted, particularly in Figure 1, the air cleaner discharge opening 50 has been made of a larger diameter than is normal for such devices such added size being provided to accommodate a most important feature of the present invention.

The size of the air cleaner outlet 50 has been substantially increased so as to receive an operating element of a carburetor. As illustrated herein, a carburetor float chamber casing 51 is mounted on the carburetor inlet manifold 12 by spaced legs 5.1 and said casing is adapted to be housed within the discharge opening 50 when the cleaner and silencer are assembled to manifold 12. Spaced below the float chamber casing 51 is a circular shoulder 12 formed on the carburetor intake manifold and which shoulder vertically supports the air cleaner-silencer assembly through a gasket 43 and flange 15.

In order to removably secure the cleaner unit to the silencer unit 11 and that assembly to the intake manifold 12, an internally threaded boss 56 is formed centrally of the float chamber casing 51. A threaded bolt 57 is screwed into said boss and extends upwardly through discharge passage 50 and through an opening 58 in the cover recess 46. A wing nut 59 is adapted to be threaded on the bolt 57 thus forcing the assembly into air tight engagement with shoulder 12. Baflies 48 are vertically supported by flange 36 of cleaner wall 35 and through such support are intended to prevent the collapse of cover 44 when nut 59 is threaded downwardly on bolt 57.

In order to insure the optimum type and quantity of air flow around the float chamber casing 51 a particular flow distributor has been designed, the preferred construction of which may be seen in Figures 1 and 2 and which will be described hereinafter.

A cylindrical casing 60 is disposed within the lower portion of the discharge passage 50 and secured to the interiorly spaced flange 26 of the silencer unit such that said casing and cylindrical member 17 of the silencer chamber form an annular silencer inlet passage 61. An inverted cup-shaped member 62 having a polygonal cross-section is secured at its surfaces of maximum diameter 63 to the inside of casing 60 and spaced from float chamber casing 51. The polygonal sides 64 of cup 62 have arcuate recesses 65 formed longitudinally thereof, thus increasing the size and exposed surface of the longitudinal chambers 66 formed by said casing and said cup.

Inasmuch as the upper end of cup 62 is closed, except for a small opening 67 to provide bolt 57 with egress therethrough, flow through the discharge opening 50 is limited by the total cross-sectional areas of the longitudinal chambers 66. It has been found when using the aforementioned type of cleaner silencer assembly that better noise silencing is attained in the silencer chamber 11 when the velocity of air going past the annular silencer passage 61 is high. Thus accounting for the special eifort to control the flow of air through air cleaner discharge passage and around the float chamber casing 51 by means of a structure such as cup 62.

Thus tracing the flow of air it will be seen that air enters the air cleaner through passage 29 flowing downwardly toward baffle 40 where the air simultaneously is exposed to oil from the sump 22 and turned upwardly through openings 34 of the air cleaner, thence through filtering material 37, after which flow is again turned downwardly by the cover 44 to flow through the hissing chamber 51,

next the air flows around the inverted cup member 62 and through the longitudinal chambers 66 and finally between supporting legs 12 into the carburetor inlet manifold.

Another species of the invention is disclosed in Figure 3. In this case, a silencer unit 70 consists of an annular silencing chamber 71 and an annular air inlet chamber 72 located interiorly of said silencing chamber. Silencing chamber 71 includes an outer wall 73 having a flange 74 formed at the upper edge thereof and said wall being turned inwardly and upwardly at the lower extremity thereof to form a bottom wall 75. A part of the inner wall of chamber 71 includes a vertical member 76 which extends inwardly at the lower edge thereof to form the upper face 77 of the annular air inlet chamber 72 and which face terminates in an upstanding cylindrical portion 78. Wall 76 is radially recessed so as to provide a circular ledge 79. Cylindrical member 78 is inwardly offset to form a circularly inclined ledge 80 and a necked portion 81. A vertical member 82 forms the remaining part of the inner wall of chamber 71 as well as forming the outer wall of air inlet chamber 72. The silencer chamber is enclosed at the top by a dished rim 83 which is secured to member 76 at the top thereof and tothe flange 74 of wall 73.

Vertical member 82 extends inwardly and upwardly from the bottom edge thereof to form the bottom face 84 of the air inlet chamber and terminates in a downwardly opening annular flange 85 which is adapted to receive a gasket 86. The inner wall of the air inlet chamber consists of a cylindrical member 87 secured at its lower portion to flange 35 and the upper portion of which member is offset inwardly to form a ledge 88 and an upstanding cylindrical neck 89. A gasket 90 is adapted to seat On the circular ledge 88. Cylindrical member 87 is concentric with and inwardly spaced from the cylindrical portion 81 so as to therewith define an annular air passage 91.

Those portions of wall 76 and cylindrical portion 78 which lie below the circular ledge 79 combine with face 77 of the silencer chamber to define an oil sump 92 for the air cleaner and over which incoming air must travel.

An air deflecting dish-shaped perforated baffle 93 is mounted circumferentially on ledge 80 of the cylindrical portion 78 to assist in redirecting incoming air upwardly through an air cleaner 100 to hereinafter be described.

Air is admitted to the annular air chamber 72 by means of an air intake conduit 94 which radially passes through an opening 95 in silencer chamber 71. The noise inherent in the operation of the carburetor and cleaner assembly is conveyed to the silencer chamber 71 via the air chamber 72 through a conduit 96 externally concentric with air inlet passage 94.

The air cleaner 100 also consists of a built-up annular structure which includes a vertical outer wall 101 having an outwardly projecting flange 102 formed at its upper edge and which wall extends inwardly from the lower edge thereof to form a bottom face 103 and upwardly from the inner edge of said face to form part 104 of an inner wall. Part 104 of the inner wall is radially recessed so as to form an annular air passage 105 which overlies the cylindrical portion 78 of the silencer unit. The inner wall of the air cleaner is completed by an upwardly flared cylindrical member 106 secured to part 104 of the inner wall. A plurality of air inlet openings 107 are formed in the bottom face 103 of the air cleaner so as to at least partially overlie baffle 93.

The annular air cleaning chamber defined by walls 101, 103, 104 and 106 is filled with any suitable air filtering material 108 and which is retained therewithin by a rimshaped grid member 109 secured across the open end of said chamber and a second grid member 110 which overlies inlet openings 107.

Overlying the entire top of the air cleaner is a cover 111. The cover consists of two spaced convex members 112 and 113, said members having any suitable sound deadening material 114 disposed therebetween. The members 112 and 113 may be secured together in any well-known manner, such as spot welding along their mutually recessed central portions 115 and 116. The lower convex member 113 is perforated so as to expose the sound deadening material 114 to noise vibrations and to provide depending baflle members 117. Baffles 117 reduce the tendency of the air leaving the air cleaner to flow spirally as it enters an air cleaner discharge passage 118 which is defined by cylindrical members 106 and 87. Baffles 117 are vertically supported by the flared portion of cylindrical member 106 and thus prevent the cover 111 from collapsing when the cleaner and silencer units are assembled.

The cover 111 is secured to the air cleaner by clamping a peripheral flange portion 119 of the cover around flange 102 of wall 101.

As in :the species of the invention shown in Figure 1, a carburetor float chamber 120 is adapted to be housed within the lower portion of the discharge passage 118 of the air cleaner. Again an internally threaded boss 121 is formed on the float chamber casing and into which boss a bolt 122 having threaded stud portions at either end thereof may be secured.

Here again, as in the previous species, the cleaner unit can be assembled to the silencer unit and the whole assembly to the carburetor in a single fastening operation which is accotmplished as follows: the cleaner unit 100 is nested within the silencer unit so as to be supported on gasketed ledge 88 and ledge 79 of the silencer structure, next the cleaner-silencer assembly is placed over the float chamber 120 such that the gasketed flange 85 of the silencer structure rests on a shoulder 123 of an inlet manifold pipe 124. At the same time, the upper stud portion of bolt 122 passes through a hole 125 in cover recesses 115 and 116 and finally a wing nut 126 is threaded down on bolt 122 so as to form substantially. air tight joints art gaskets 86 and 90.

Thus, the flow of air to the carburetor is from the inlet conduit 94 to the annular chamber 72, whence it flows upwardly through the annular passage 91, then downwardly through another annular passage 105 to the oil sump 92 where it is redirected upwardly by baflle 93 through filtering material 108. The air is finally deflected downwardly by the cover 111 to flow out the discharge passage 118 and around the carburetor float chamber casing 120 into the inlet manifold pipe 124.

The flow of noise through the assembly is, of course, just the reverse of that of the air until it reaches the annular air chamber 72 where the noise vibrations are directed through conduit 96 into the silencing chamber 71.

' The general arrangements as heretofore described, have the distinct advantage of lowering the overall height of the combined engine and air cleaner-silencer assembly. Such a construction is particularly advantageous where a downdraft carburetor is employed since such a carburetor is of necessity located above the intake manifold. Inasmuch as the overall tendency in automobile design is to lower the vehicle silhouette, my invention contributes appreciably to the realization of such end by reducing the overall vertical displacement of the carburetor and air cleaner-silencer assembly.

In addition, by developing an air cleaner-silencer assembly which is adapted to house a part of a carburetor it has been necessary to redesign the assembly itself, as has been described above, to insure that the reduced vertical clearance of the oleaner-silencencarburetor assembly is compatible with quiet and efficient operation.

While only two illustrations of my invention have been shown, it is not intended thereby to so limit the scope of my invention inasmuch as it is apparent that other variations of such structure 'may be achieved within the comprehension of said invention.

I claim:

1. In an air cleaner and silencer assembly having a silencer which includes an annular chamber having a recessed upper wall, an annular air cleaner being adapted to seat within said recessed wall, said cleaner and said silencer having outer walls which define an annular air inlet passage and inner Walls which define an air outlet chamber, an inverted cup-shaped member having a plurality of longitudinal recesses formed peripherally thereof, a cylindrical member mounted within said outlet and circumscribed about said cup-shaped member, said cylindrical member cooperating with said recesses to form a plurality of outlet passages between said members, said cup being adapted to internally receive an opera-ting element of an internal combustion engine.

2. The combination of an air cleaner and silencer assembly and a carburetor, said assembly including an annular silencer chamber having a recessed upper wall, an air cleaner being adapted to seat within said recess, said cleaner and said silencer having outer walls which define an annular air inlet passage and inner walls which define an air outlet chamber, an inverted cup-shaped member disposed within said outlet and having a plurality of longitudinal recesses formed peripherally thereof, said cupshaped member being adapted to receive a carburetor float chamber, a cylinder circumscribed about said member and secured within said outlet, said cylinder in cooperation with said recesses forming a plurality of outlet passages leading to said carburetor.

3. In an air cleaner and silencer assembly including an annular silencer chamber having an oil sump formed in the upper wall thereof, an annular air cleaner being adapted to seat within said sump, a downwardly inclined perforated b-affle cantilevered from the inner wall of said air cleaner. a circular ledge formed within said sump and being adapted to support the free end of said baflle, means being adapted to space said baflle from the bottom face of said cleaner, said cleaner and said silencer having outer walls which define an annular inlet opening and inner walls which define a discharge chamber, an inverted cup-shaped member disposed within said chamber and having a plurality of longitudinal recesses formed in the peripheral surface thereof, a cylinder secured within said discharge chamber and being adapted to circumscribe said cup-shaped member so as to form a plurality of discharge passages.

4. In an air cleaner and silencer assembly having a silencer comprising an annular chamber having a partially cut-a-way upper wall, an upwardly opening annular member being adapted to be secured within said cut-a-way upper wall, an annular air cleaner adapted to be seated within said annular member, said annular member and said air cleaner having outer walls which define an annular air inlet and inner walls which define a discharge outlet, an inverted cup-shaped member disposed within said outlet and having a plurality of longitudinal recesses formed peripherally thereof, a cylinder being adapted to circumscribe said cup and secured within said discharge outlet so as to define a plurality of discharge passages.

5. In an air cleaner and silencer assembly including a silencer which comprises an annular chamber having a partially cut-a-way upper wall, an upwardly opening annular sump member being adapted to be secured within said cut-a-way wall, an air cleaner adapted to be seated within said sump member, said air cleaner comprising an annular chamber having air openings formed in the upper and lower walls thereof, a downwardly inclined perforated baifie cantilevered outwardly from the inner wall of said air cleaner chamber, a plurality of elements depending from the bottom face of said cleaner chamber and being adapted to space said b-afile from said bottom wall, said annular sump member and said air cleaner having outer walls which jointly define an annular air inlet and inner walls which jointly define a discharge outlet, an inverted cup-shaped member disposed within said discharge outlet and having a plurality of longitudinal recesses formed peripherally of said cup-shaped member, a cylinder secured within said outlet and adapted to circumscribe said member so as to define a plurality of discharge passages leading to a carburetor inlet.

6. In combination, an air cleaner and silencer assembly and carburetor, said assembly including a silencer having a first annular chamber, a second annular chamber disposed interiorly of said first chamber, an air inlet opening communicating with said second chamber, the inner wall of said second annular chamber extending upwardly beyond said chamber, the upper wall of said latter chamber having a cylindrical portion extending upwardly and concentrically spaced from the inner wall of said chamber so as to form an annular air passage therebetween, a dish-shaped baflle member disposed peripherally of the cylindrical portion of said upper face, a recess formed in the inner wall of said first annular chamber above said bafile, an annular air cleaner adapted to seat within said recess, the inner wall of said air cleaner having a portion longitudinally abutting against the inner wall of said second annular chamber, said abutting walls jointly defining a discharge outlet, the remaining portion of said air cleaner inner wall being recessed so as to overlie and be concentric with said annular air passage, said discharge outlet being adapted to receive an operating element of a carburetor.

7. In combination, an air cleaner and silencer assembly and a carburetor, the silencer unit including a pair of concentric annular chambers, the inner annular chamber being an air inlet chamber, said outer annular chamber being a silencing chamber, an air inlet conduit passes radially through said silencing chamber and communicating with said air inlet chamber, the air cleaner including an annular chamber having air inlet and outlet openings provided in the lower and upper walls respectively, a filtering material intermediate said openings, said filtering material being contained within said chamber by a pair of rim-shaped grid members adjacent said respective openings, said silencing chamber being radially recessed to receive said air cleaner therewithin, the inner walls of said air cleaner and said air inlet chamber jointly defining an air outlet passage, the upper face of said air inlet chamber terminating in an upwardly projecting cylindrical member concentrically spaced from the inner wall of said air inlet chamber, said cylindrical member cooperating with said inlet chamber inner wall and a downwardly opening recessed portion of said air cleaner to define an air passage communicating with said air inlet chamber and said air cleaner air inlet openings, said air outlet passage being adapted to receive an operating element of said carburetor, and a carburetor inlet pipe being adapted to support said cleaner and silencer assembly.

8. In combination, an air cleaner, an air silencer and a carburetor inlet manifold, said manifold including a flange, said silencer adapted to be supported on said flange, said silencer having a recessed upper wall, said air cleaner being adapted to nest within said recessed wall and a single fastening means being adapted to removably secure said air cleaner within said silencer recess and said silencer upon said manifold flange.

9. An internal combustion engine including in combination an air cleaner, an air silencer and a carburetor, said carburetor including an inlet manifold having a flange formed thereon and a float chamber casing mounted on said manifold above said flange, said silencer having a recessed upper wall, said air cleaner being adapted to nest within said recessed wall, said cleaner and silencer having a common axial discharge passage, said silencer being adapted to be mounted on said manifold flange such that said carburetor float chamber casing is housed within said discharge passage and fastening means mounted upon said float chamber casing so as to removably secure said air cleaner within said silencer and said silencer together with said cleaner upon said manifold flange.

10. In an air cleaner and silencer assembly including an annular silencer chamber having an annular oil sump formed in the upper wall thereof, an annular air cleaner being adapted to seat within said sump, a downwardly and outwardly inclined circular baflle cantilevered from the inner wall of said air cleaner, a circular ledge formed within said sump, the free end of said bathe being adapted to be supported upon said ledge, and a plurality of members depending from said air cleaner, said members cooperating with said baffle to maintain the bottom wall of said air cleaner at a fixed vertical distance with respect to said sump.

11. An air cleaner assembly having an upwardly opening annular member formed to provide an oil sump, an annular filter housing having its inner wall substantially aligned with and adapted to seat upon the inner wall of said annular member, a radial baffie plate secured to the inner wall of said filter housing and inclined downwardly and outwardly beneath said filter housing, a plurality of depending radial elements formed on said filter housing and adapted to space the outer end of said bafile plate apart from the bottom of said filter housing, said depending elements being further adapted to urge said baffle plate in engagement with said annular member and within said oil sump and to hold said filter housing in spaced relation thereabove when said filter housing is secured to said annular member.

12. An air cleaner and silencer assembly including an annular air silencer having a recessed upper wall formed to provide an oil sump, an annular air cleaner associated with said silencer and disposed over said oil sump, a radial baflle element secured to the inner wall of said air cleaner and inclined downwardly and outwardly therefrom, a ledge formed about said oil sump and adapted to receive the free end of said bafile element, and a plurality of depending radially extending legs formed below said air cleaner, said legs being adapted to space said baffle apart from said air cleaner and to support said air cleaner in spaced relation above said sump when said air cleaner is secured to said air silencer.

13. An air cleaner-silencer assembly for use with a down draft carburetor having a part thereof mounted in spaced relation over the inlet passage of said carburetor, said assembly being formed to provide an air outlet chamber therein for receiving said carburetor part, and an inverted cup-shaped member disposed within said chamber and about said carburetor part, said member having a plurality of longitudinal recesses formed peripherally thereof and disposed adjacent the walls of said chamber for forming discharge passages in cooperation with said walls for the passage of air through said outlet chamber to said carburetor inlet passage.

References Cited in the file of this patent UNITED STATES PATENTS 1,945,180 Carter Jan. 30, 1934 2,143,350 Kamrath Jan. 10, 1939 2,150,745 Mieras et al Mar. 14, 1939 2,236,273 Nash Mar. 25, 1941 2,287,629 Mieras W..- June 23, 1942 2,440,245 Chevigny Apr. 27, 1948 2,514,543 Hamman July 11, 1950 2,582,915 Sebok Jan. 15, 1952 2,661,937 Kittler Dec. 8, 1953 2,681,123 Sebok June 15, 1954 FOREIGN PATENTS 880,587 France Jan. 4, 1943 922,975 France June 24, 1947