US3746475A

US3746475A - Double-acting swashplate compressor

Info

Publication number: US3746475A
Application number: US00112335A
Authority: US
Inventors: R Johnson
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1971-02-03
Filing date: 1971-02-03
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17

Abstract

In preferred form, a fluid compressor for an automobile air conditioning system having three cylinders within a cylinder block which is supported within a compressor casing by one end of the casing. Pistons are reciprocated within the cylinders by piston rods which extend through a cylinder head into the interior of the casing. A drive shaft extending through the other end of the casing rotates an inclined swashplate which coacts with the piston rods to reciprocate the pistons. A high pressure discharge passage is centrally formed on both ends of the cylinder block and are interconnected by a passage axially extending therebetween. A low pressure intake passage is formed on the cylinder ends and encircles the discharge passage.

Description

Unlted States Patent 1 1 1 1 3,746,475 Johnson July 17, 1973 DOUBLE-ACTING SWASHPLATE Primary Examiner-William L. Freeh COMPRESSOR Attorney-W. S. Pettigrew. .I. C. Evans and K. H. [75] Inventor: Ralph S. Johnson, Rochester, Mich. M [73] Assignee: General Motors Corporation, Detroit, MlCh. [22] Filed: Feb. 3, 1971 In preferred form, a fluid compressor for an automobile 1 PP No.1 112,335 air conditioning system having three cylinders within a cylinder block which is supported within a compressor 52 us. (:1. 417/269 easing by one end of the easing Pistons are 511 1m. (:1. F04b 1/12 Preeeted Within the cylinders by P reds which 581 Field of Search 417/269; 91/502 tend through a cylinder head into the interior of the casing. A drive shaft extending through the other end [56] References Cited of the casing rotates an inclined swashplate which co- UNITED STATES PATENTS acts with the piston rods to reciprocate the pistons. A- I high pressure discharge passage is centrally formed on 2,991,723 7/1961 Zabaty 1 417/269 both ends f the i d l k d are interconnected 3,552,886 l/197l Olson 417/269 b n t d th b t A I w 2479 876 8/1949 Sherman 417 269 y a pasiage y m e 0 2945444 7/1960 Leissner n 417/269 pressure lntake passage is formed on the cylinder ends 3,215,341 11/1965 Francis 417/269 and encircles the dischaige P 3,538,706 11/1970 Tocpel 417/269 FOREIGN PATENTS OR APPLICATIONS Germany 91/502 I 1 Claim, 7 Drawing Figures DOUBLE-ACTING SWASHPLATE COMPRESSOR This invention relates to fluid compressors for air conditioning applications.

It is desirable that fluid compressors in automobile air conditioning systems be lightweight and subject to modification to change the compressor capacity. Another desirable feature is that the temperature of the compressor be kept as low as possible.

The subject air conditioning compressor utilizes a cylinder block having three cylinder bores arranged symmetrically about a centerline of the block. Pistons within the cylinders are connected to piston rods which coact with a swashplate drive assembly to reciprocate the pistons causing compression of fluid. The capacity of the compressor is easily changed by simply providing a cylinder block with smaller diameter bores and matching small diameter pistons. Because of the symmetrical arrangement of the bores and pistons, no unbalancing is encountered due to this change. An annular channel in the cylindrical surface of the pistons is varied in depth to provide the same weight for both size pistons. This permits use of the same swashplate drive assembly in all capacity compressors.

The subject compressor includes cylinder heads covering either end of the cylinder block to define the compression chambers on either side of the doubleended pistons. A centrally located discharge passageway is formed within the end cylinders for receiving fluid from the compression chambers after compression. A bypass passageway axially through the cylinder block and between the cylinder heads interconnects the two discharge passageways with an outlet from the compressor. Intake passageways formed in the cylinder heads encircle the discharge passageways and are separated therefrom by more or less circular wall or ridge portions. The inlet passageways open directly to the interior of the compressor casing. By this arrangement, the warm discharge fluid of the compressor is surrounded by the relatively cool fluid in the interior of the casing. This keeps the temperature of the compressor at a desirably lower temperature.

Therefore, an object of the invention is the provision of a lightweight fluid compressor whose capacity may be readily varied simply by the substitution of a cylinder block assembly having different diameter cylinder bores with pistons to match.

A further object of the invention is to provide a lightweight fluid compressor in which the high-temperature discharge fluid is confined to the central region of the cylinder block and where it is surrounded by the lowtemperature intake fluid.

Further objects and advantages of the present invention will be apparent from the following detailed description, reference being had to the accompanying drawings in which a preferred embodiment is clearly shown.

IN THE DRAWINGS:

FIG. 1 is a vertical sectioned view of the compressor;

FIG. 2 is a sectioned view along section line 2--2 in FIG. 1 and looking in the direction of the arrows;

FIG. 3 is a sectioned view along section line 3-3 in FIG. 1 and looking in the direction of the arrows;

FIG. 4 is a sectioned view along section line 44 in FIG. 1 and looking in the direction of the arrows;

FIG. 5 is a sectioned view along section line 5-5 in FIG. 1 and looking in the direction of the arrows;

FIG. 6 is a sectional view taken along section line 6-6 in FIG. 5 and looking in the direction of the arrows; and

FIG. 7 is a partial view of a smaller capacity compres sor similar to FIG. 1 and broken away to reveal a smaller diameter cylinder and piston.

In FIG. 1, a compressor 10 is illustrated. Compressor 10 includes a cylindrical casing or housing 12 having and members 14 and 16 enclosing an interior space 18. The end member 14 is sealed in relation to housing 12 by an O-ring 22. In turn, the flange 20 is joined to the housing 12 by a weld 24 to produce a leakproof connection. The other end member 16 is fastened to the housing 12 by a crimp 26. An Q-ring type sea] 28 between the end 16 and casing 12 produces a leakproof connection.

A compressor cylinder block assembly 30 is supported within the interior space 18 by the end 16. The cylinder block assembly 30 includes a cylinder block 32 with three parallel cylinder bores 34 arranged symmetrically about the axis of the cylinder block. The ends of the cylinder block 32 are covered by valve plates 36 and

cylinder heads

38 and 39. On one end, the valve 36 and cylinder head 39 are secured between the end member 16 and the cylinder block 32 by three bolt fasteners 42 which are threaded into the end 16. An end cover 40 extends over the cylinder head 38 which is on an opposite end of the block to end member 16.

Three pistons 44 are disposed withinthe cylinders 34 for reciprocation. The pistons 44 have a channel 46 formed in their cylindrical surface and annular leg portions 48 which contact the cylinders 34. Three piston rods 50 are connected at reduced diameter ends 52 to pistons 44. The piston rods 50 extend from piston 44 through a valve plate 36, the cylinder head 38 and cover 40 into the interior l8. O-ring type seals 54 encircle the piston rods 50 and prevent fluid leakage from cylinders 34 therebetween.

A swashplate 56 is affixed to a drive shaft 58 for rotation and includes parallel face surfaces which are at an inclined angle with respect to the drive shaft axis. An end 59 of the shaft 58 is supported in a bearing recess 60 formed within a boss 61 of cover 40. Needle bearings 62 between end 59 and boss 61 are provided to reduce friction therebetween during rotation. The shaft 58 extends through the interior 18, through a bore 64 in end 14 and through a cylindrical] extension 66 on the end 14. Needle bearings 68 between shaft 58 and bore 64 reduce friction therebetween, during rotation. A seal assembly 70 supported by cylindrical extension 66 encircles the shaft 58 and prevents the loss of fluid from interior space 18. The exterior end 72 of shaft 58 is adapted to be rotated by the auto engine to cause rotation of the shaft 58 and swashplate 56.

The swashplate 56 is pressed onto shaft 58 for rotation therewith. The circular swashplate 56 is inclined with respect to the axis of shaft 58 so that upon rotation of the shaft, the peripheral edge of the swashplate moves axially with respect to the shaft 58. U-shaped saddle members 74 which are formed in the ends of piston rods 50 straddle the peripheral edge of the swashplate 56. Semi-spherical thrust bearing shoes 76 between the face surfaces of the swashplate 56 and per tions 77 of the saddle members 74 slide along the face surfaces of swashplate 56 as it is :rotated. The pistons 44 and piston rods 50 are reciprocated by the peripheral edge as it moves axially with respect to shaft 58 during rotation. This translation of rotational movement of shaft 58 into reciprocal movement of the piston rods 50 and pistons 44 produces the fluid pumping action. As the swashplate 56 rotates and moves the piston rods 50 and pistons 44 axial thrust forces are exerted on shaft 58. Needle bearings 78 between the swashplate 56, end plate 40 and end 14 reduce friction caused by the axial thrust force.

When the pistons 44 are moved within the cylinders 34, fluid is compressed on one side of the piston while fluid is drawn into the cylinder on the other side of the piston for subsequent compression. The fluid is drawn into the left-hand compression chamber in FIG. 1

through an intake passage or channel 80 formed in the end 16 by an annular recess. The fluid passes from interior 18 through the passage 80 and into intake ports 82 in cylinder head 38, as best shown in FIG. 5.

Fluid is drawn into the right-hand cylinder 34 through intake ports 84 in cover 40 and cylinder head 38, as best shown in FIG. 4. Fluid passes into cylinder 34 under the control of reed valves 86 formed in the valve plate 36, as best shown in FIG. 3. The reed valves 86 are thin, flexible portions of plate 36 separated from the remaining portion of the plate by a cutout 88. Elongated holes 90 in the valve plates 36 permit piston rods 50 to pass through the valve plate 36. The valve plate covering the left end of the cylinder block 32 is identical to plate 36 in FIG. 3 with holes 90 therein. The reed valves 86 prevent hydraulic fluid within the cylinders 34 from being discharged through the intake ports 82 and 84 as fluid is compressed.

Fluid is discharged from the cylinders 34 through outlet ports 92 in the cylinder heads 38 as shown in FIGS. 4 and 5. The fluid passes from outlet ports 92 into discharge passages 94 formed by a centrally located recess in the end member 16 and the cover 40. The discharge passages 94 are positioned centrally on the end 16 and the cover 40 and a more or less circular wall 96 on the end member 16 separate the discharge passage 94 from the intake passage 80. An axially directed crossover passage 98 axially through the cylinder block 32 interconnects the discharge passages 94. An outlet opening 99 directs the fluid from the compressor 10 through an outlet fitting (not shown) therein which also acts as a pressure relief valve.

Fluid is prevented from being drawn from the discharge passages 94 back into the cylinders 34 by reed valves 100 which cover the outlet ports 92, as shown in FIG. 6. The reed valves 100 are held against the cylinder head 39 by a rivet fastener 102 and a backup strip 104. The backup strip 104 has a tab 106 which engages a hole 108 for aligning the reed valve 100 over the outlet port 92. The overlying backup strip 104 restricts the movement of the reed valve 100 to prevent excessive deflection which might damage the reed valve.

An important feature of the compressor is its adaptability for changing compressor capacity by substituting a new cylinder block having smaller cylinders and smaller pistons. In FIG. 7, a compressor with smaller cylinders and pistons is shown. A new cylinder block 110 with smaller diameter cylinders 112 reduces the compressor capacity. Smaller diameter pistons 114 are used in the cylinders 112. The channel 116 of the smaller diameter piston 114 is shallower than channel 46 in piston 44 in FIG. 1. This permits both pistons to be approximately the same weight. This is desirable for use of the same swashplate assembly in compressors of varying capacity.

Also of importance in this compressor is the confinement of the relatively warm discharge fluid to a central region of the cylinder block. In this region, it is encircled by cool fluid within the interior of the casing. This reduces the compressors operating temperature as well as the temperature of its outer surface.

While the embodiments of the invention herein described are preferred form, other embodiments may be tioning system comprising: a cylindrical compressor casing with first and second end members enclosing an interior space; a cylinder block assembly being supported by and fastened to said first end member within said interior space; said cylinder block assembly including a cylinder block with cylinder bores extending therethrough normal to said first end member and arranged symmetrically about its axis, a valve plate on both ends of said cylinder block covering said cylinder bores, a cylinder head on both ends of said cylinder block covering said valve plates; a cover on the end of said cylinder block opposite said first end member; pistons in said cylinder bores forming compression chambers on either side of said pistons; piston rods attached to said pistons and extending through one of said cylinder heads and said end cover into said interior space; a drive shaft supported by said second end member and by said cover for rotation within said interior space; a swashplate affixed to said drive shaft between said cover and said second end member having parallel face surfaces which are inclined with respect to the axis of said drive shaft; U-shaped saddle portions of said piston rods which straddle the peripheral edge of said swashplate and contact said face surfaces for transforming rotational movement of said swashplate into linear re- I ciprocation of said piston rods and said pistons; an inlet opening through said first end member for passing low pressure fluid into said interior space; an annular intake passage formed in said first end member; inlet means through said cylinder heads and said cover for passing fluid from said interior space and said intake passage into said compression chambers; inlet valves formed in said valve plates for controlling fluid flow into said compression chambers; a discharge passage in a central portion of said first end member separated from said surrounding intake passage by an annular wall; another discharge passage in a central portion of said cover in' terconnected to said first discharge passage by a crossover passage through said cylinder block and cylinder heads; outlet means through said cylinder heads for passing fluid from said compression chambers into said discharge passages; outlet valves formed in said valve plates for controlling fluid flow from said compression chambers; an outlet opening through said first end member fluidly connected with said discharge passages for passing fluid from said compressor.

Claims

1. A fluid compressor for an automobile air conditioning system comprising: a cylindrical compressor casing with first and second end members enclosing an interior space; a cylinder block assembly being supported by and fastened to said first end member within said interior space; said cylinder block assembly including a cylinder block with cylinder bores extending therethrough normal to said first end member and arranged symmetrically about its axis, a valve plate on both ends of said cylinder block covering said cylinder bores, a cylinder head on both ends of said cylinder block covering said valve plates; a cover on the end of said cylinder block opposite said first end member; pistons in said cylinder bores forming compression chambers on either side of said pistons; piston rods attached to said pistons and extending through one of said cylinder heads and said end cover into said interior space; a drive shaft supported by said second end member and by said cover for rotation within said interior space; a swashplate affixed to said drive shaft between said cover and said second end member having parallel face surfaces which are inclined with respect to the axis of said drive shaft; U-shaped saddle portions of said piston rods which straddle the peripheral edge of said swashplate and contact said face surfaces for transforming rotational movement of said swashplate into linear reciprocation of said piston rods and said pistons; an inlet opening through said first end member for passing low pressure fluid into said interior space; an annular intake passage formed in said first end member; inlet means through said cylinder heads and said cover for passing fluid from said interior space and said intake passage into said compression chambers; inlet valves formed in said valve plates for controlling fluid flow into said compression chambers; a discharge passage in a central portion of said first end member separated from said surrounding intake passage by an annular wall; another discharge passage in a central portion of said cover interconnected to said first discharge passage by a crossover passage through said cylinder block and cylinder heads; outlet means through said cylinder heads for passing fluid from said compression chambers into said discharge passages; outlet valves formed in said valve plates for controlling fluid flow from said compression chambers; an outlet opening through said first end member fluidly connected with said discharge passages for passing fluid from said compressor.