US2946503A - Air compressor - Google Patents

Description

July 26, 1960 w. B. THOMPSUN AIR COMPRESSOR Filed May 22,1957

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United States lPatent O AIR coMPREssoR William B. Thompson, Saginaw, Mich., assignorto General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed May 22, 1957, Ser. No. 660,800

1 Claim. (Cl. 230-190) This invention relates to iiuid pumps and more particularly to reciprocating piston type air compressors.

An object of the invention is to provide an improved Another object is to provide an air compressor which is adapted for coaxial mounting and direct drive engagement with engine driven accessories such as a vehicle generator.

A further object is to provide an air compressor of the reciprocating piston type employing an improved and simplied crank rotor.

A still further object is to provide a compressor em ploying straight liow air displacement wherein air enters `the compressor crankcase, passes through an intake valve in the reciprocating pistonand is expelled Jthrough an exhaust valve in the compressor cylinder head.

A further object is to provide a compressor rofthe type referred to wherein the piston and connecting rod are driven by a crank rotor which is rotatably supported in the crankcase in substantial alignment with the vertical centerline of the piston.

Yet a further object is to provide a device of the stated character wherein the diameter of the rotor is in excess of maximum crankpin throw.

A still further object is to provide a compressor ernploying a rotor construction of the stated character including means for dynamically balancing the Compressor.

Yet another object isvto` provide a compressor of the stated character having a one-piece cylinder and cylinder head. 1

These andother objects, advantages and` features of the invention will become more fully apparent as reference is hadto the accompanying specification and drawings wherein:

Fig. l is a rear elevational view of the invention showing its relationship with and means of attaching to a vehicle engine driven generator;

Fig; 2 is an enlarged side elevational view, partly in section, showing thei, structure and arrangement of the invention, certain parts being broken away to more clearly illustrate the construction thereof; and

Fig.4 3 is an enlarged fragmentary view, partly in section, looking in the direction of arrows 3 3 of Fig. 2.

Referring now to the` drawings and particularly Figs. l and 2, there is illustrated a single cylinder air compressor wherein the reference numeral 2 designates generally an integral cylinder wall and cylinder head casting. Connected to the downwardly facing iianged bottom 4 of casting 2, by means of bolts 6, is a crankcase 8. At one side 1l) thereof crankcase 8 is provided with a relatively large diameter circular opening 12, the axis of which extends perpendicular to the axis of cylinder 2. At the other side 14, crankcase 8 is provided with an apertured stem 16 providing communication between the interior 18 of crankcase 8 and atmosphere. In accordance with one feature of the invention, there is press fitted into the base of circular opening 12`the outer race 19 of a needle bearing assembly 20, the inner race of which is formed to provide a crank rotor 22. Centrally thereof rotor 22 s formed with an axially extending splined opening 24 which is adapted to receive a splined stub shaft 26. Covering the open outer face of rotor 22 is a cover plate 27 having a central aperture 29 aligned with opening 24. Stub shaft 26 is preferably formed as an integral extens ion ofthe armature rotor (not shown) of generator 28. Extending axially through rotor 22 in radially offset relation to splined aperture 24 is a second aperture 30. Press fitted in aperture 30 is a sleeve bearing 32 which, in turn, receives the inner end 34 of a hollow pin 36. Piu 36, in turn, is rigidly connected at its outer end 38 to the -lower enlarged end 40 of a connecting rod 42. At its upper end 44, connecting rod 42 is provided with a sleeve bearing 46 which surrounds a wrist pin 48 carried by a piston 50. It should be noted that connecting rod 42 is dog legged or offset so that the bearing 46 for wrist pin 48 and bearing 32for crankpin 34 are in substantial vertical alignment. As1 a result, the overall depth requirements for the crankcase housing is considerably reduced.

In order to effect dynamic balancing of the compressor assembly, rotor 22 is provided with a series of additional axially extending drilled apertures 52 in the crankpin side of the rotor which impart counter-balancing effect thereto without damaging the peripheral portion engaged by needle bearing assembly 20.

As pointed out previously, the cylinder and cylinder head are formed as an integral casting. According to another feature of the invention, the compressor exhaust valve assembly is so constructed and arranged as to permit'rernoval thereof without access to the interior of the compressor. As seen in Fig. '2, casting 2 is provided with an internally threaded pilot portion 54 having a centrally disposed boss 56 at the base thereof through which extends an exhaust port 58 communicating with the compression chamber 60 of the compressor. Threadedly disposed in threaded pilot portion 54 is an exhaust line fitting 62 having a central aperture 64 therein provided with a counter bore 66 at the base thereof. Disposed between counter bore 66 'and the upper face 68 of boss 56 is compression spring 70 and a plate valve 72. It will of course be apparent that valve 72 is normally urged to the position closing port 58 except when the compression in compression chamber 60 exceeds the resistance of spring 70.

In order to admit air to thecompression chamber 60 through inlet 16, the piston 50 is provided with a poppet valve 74 in the top wall 76 thereof. In operation, poppet valve 74 opens during piston downstroke allowing air in the crankcase to enter the compression chamber. As the piston rises in compression stroke, the poppet valve 74 moves to closed position thus preventing the escape of air from the compression chamber 60 except through exhaust port 58.

As shown particularly in Fig. l, the crankcase 8 is provided with integral ears 78 and 80 which are adapted to be connected to the rear end 82 of generator 28 by means of the usual bolts 84 customarily used in maintaining the generator in assembled relation. It will thus be seen that a compressor of the'type described may be quickly and easily installed in conventional vehicle generators with a minimum of modification of the latter. In addition, because of the simplicity of attachment and ease of accessibility, the compressor may be quickly serviced, repaired or replaced. It `will also be evident that the extremely shallow crankcase depth requirement resulting from the novel crank rotor construction virtually eliminates the possibility of interference with other engine accessories orA components` While but one embodiment of the invention has been shown and described, it will be evident that other changes 3 and modifications may be made therein. It is, therefore, to be understood that it is not intended to limit the invention to the embodiment shown, but only by the scope of the claim which follows.

I claim:

In a fluid compressor having a piston movable by a connecting rod, an anti-friction bearing assembly mounted in said compressor in substantial vertical alignment with said piston, a statically unbalanced circular rotor carried by said bearing assembly, said rotor having a splined aperture extending axially through the center thereof for engagement with a splined driving shaft, means forming an axially extending aperture iu the body of said rotor radially offset from said splined aperture, and means carried by said connecting rod operatively engaging said last mentioned aperture, the lower portion of said connecting rod being offset axially from the upper portion thereof.

References Cited in the file of this patent UNITED STATES PATENTS Miles Iuly 17, 1906 Snyder May 28, 1912 Kellogg May 4, 1919 Thomas Nov. 20, 1928 Iaussaud .Tune 4, 1929 Heide May l0, 1932 Paul et al. Dec. 9, 1941 Pierce Iuly 7, 1942 Shoemaker Aug. 3, 1943 Daeg ...1 May 8, 1951 Bjorklund Sept. 28, 1954 Drude June 5, 1956 Keel Aug. 21. 1956

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