4-Stage diaphragm compressor

[0001] 1. Field of the Invention

[0002] This invention relates to compressors, specifically to high pressure portable compressors.

[0003] 2. Description of Prior Art

[0004] Despite its usefulness, there are currently no compact portable compressors exceeding 135 psig available on the market. Compared to ordinary low pressure portable compressors, which can be found in the marketplace, high pressure compressors have a much wider application range. For example, the high pressure air flow from the high pressure air compressor can be used to lift a car, to unscrew the bolts of a flat tire, to provide air flow for air bank spray paint, fill scuba diving tanks, etc.

[0005] Most prior art compressor designs use either a single stage or a 2-stage piston type design, which basically consist of one or two reciprocating moving pistons. Using this design it is virtually impossible to achieve high pressures unless they are driven by large motors. This is mainly due to the large frictional forces between the piston rings and their cylinder that have to be overcome. Large friction between the piston rings and their cylinder is necessary in order to properly seal the gap between the piston rings and their inner cylinder walls, such that high pressure can be developed.

[0006] An alternate design to a piston type compressor is a diaphragm type compressor. Diaphragm type compressors are seldom used, mainly because of the low displacement volume that a diaphragm air compressor can provide.

[0007] In order to avoid having to use a large driving motor the portable air compressor of this application, unlike most air compressors available, uses a diaphragm type design. And in order to generate sufficient air flow and high pressure with a small motor, the portable air compressor of this application has 4-stages.

[0008] In accordance with the present invention, a portable compressor can generate high pressures despite having a small motor by utilizing a 4-stage diaphragm type design.

[0009] Besides the objects and advantages of the high pressure portable 4-stage diaphragm compressor described in my above patent, several objects and advantages of the present invention are:

[0010] (a) to provide a portable air compressor that has a high pressure rating;

[0011] (b) to provide a portable air compressor that can be used to lift cars;

[0012] (c) to provide a portable air compressor that can be used to unscrew tire bolts;

[0013] (d) to provide a portable air compressor that can be used to fill air bank cylinders for paint spray;

[0014] Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

[0015] In the drawings, closely related figures have the same number but different alphabetic suffixes.

[0016] FIG. 1A shows a cross-section of the assembled mechanical parts of the 4-stage diaphragm compressor.

[0017] FIG. 1B shows a sectional view of the assembled mechanical parts of the 4-stage diaphragm compressor.

[0018] FIG. 1C shows another sectional view of the assembled mechanical parts of the 4-stage diaphragm compressor.

[0019] FIG. 2A shows the top view of the bottom casing block.

[0020] FIG. 2B shows the front view of the bottom casing block.

[0021] FIG. 2C shows the right view of the bottom casing block.

[0022] FIG. 2D shows the back view of the bottom casing block.

[0023] FIG. 2E shows the left view of the bottom casing block.

[0024] FIG. 2F shows a sectional view of the bottom casing block.

[0025] FIG. 3A shows the top view of the top casing block.

[0026] FIG. 3B shows the front view of the top casing block.

[0027] FIG. 3C shows the right view of the top casing block.

[0028] FIG. 3D shows the back view of the top casing block.

[0029] FIG. 3E shows the left view of the top casing block.

[0030] FIG. 3F shows a sectional view of the top casing block.

[0031] FIG. 4A shows the top view of the assembled 4-stage diaphragm compressor without the tubing.

[0032] FIG. 4B shows the front view of the assembled 4-stage diaphragm compressor without the tubing.

[0033] FIG. 4C shows the right view of the assembled 4-stage diaphragm compressor without the tubing.

[0034] FIG. 4D shows the back view of the assembled 4-stage diaphragm compressor without the tubing.

[0035] FIG. 4E shows the left view of the assembled 4-stage diaphragm compressor without the tubing.

[0036] FIG. 5A shows the top view of the assembled 4-stage diaphragm compressor.

[0037] FIG. 5B shows the front view of the assembled 4-stage diaphragm compressor.

[0038] 5C shows the right view of the assembled 4-stage diaphragm compressor.

[0039] 5D shows the back view of the assembled 4-stage diaphragm compressor.

[0040] 5E shows the left view of the assembled 4-stage diaphragm compressor.

[0041] FIG. 6 shows an alternate diaphragm.

[0042] FIG. 7 shows an arrangement for the 4-stage diaphragm compressor where a gearbox is used.

[0043] 10 cylinder body 1

[0044] 11 diaphragm 1

[0045] 11A alternate diaphragm

[0046] 12 cylinder head 1

[0047] 13 valve gasket 1

[0048] 14 valve cover 1

[0049] 15 piston 1

[0050] 15A alternate piston

[0051] 16 piston cap 1

[0052] 20 cylinder body 2

[0053] 21 diaphragm 2

[0054] 22 cylinder head 2

[0055] 23 valve gasket 2

[0056] 24 valve cover 2

[0057] 25 piston 2

[0058] 26 piston Cap 2

[0059] 30 cylinder body 3

[0060] 31 diaphragm 3

[0061] 32 cylinder head 3

[0062] 33 valve gasket 3

[0063] 34 valve cover 3

[0064] 35 piston 3

[0065] 36 piston cap 3

[0066] 40 cylinder body 4

[0067] 41 diaphragm 4

[0068] 42 cylinder head 4

[0069] 43 valve gasket 4

[0070] 44 valve cover 4

[0071] 45 piston 4

[0072] 46 piston cap 4

[0073] 50 cam

[0074] 51 flywheel half 1

[0075] 52 flywheel half 2

[0076] 53 spacer

[0077] 54 piston ball bearing

[0078] 55 valve

[0079] 56 top casing bearing

[0080] 57 bottom casing bearing

[0081] 58 fan

[0082] 60 piston cap screw

[0083] 60A piston pin

[0084] 60B piston pin 2

[0085] 61 valve pin

[0086] 62 cylinder cap screw

[0087] 63 cam set screw

[0088] 64 flywheel screw

[0089] 65 cam retaining ring

[0090] 66 motor shaft retaining ring

[0091] 67 cover screw

[0092] 68 casing cap screw

[0093] 69 casing nut

[0094] 70 motor

[0095] 71 motor shaft

[0096] 80 bottom casing block

[0097] 81 top casing block

[0098] 82 front cover plate

[0099] 83 left cover plate

[0100] 84 back cover plate

[0101] 85 right cover plate

[0102] 90 stage-1 inlet connection

[0103] 91 stage-1 outlet connection

[0104] 92 stage-inlet connection

[0105] 93 stage-2 outlet connection

[0106] 94 stage-3 inlet connection

[0107] 95 stage-3 outlet connection

[0108] 96 stage-4 inlet connection

[0109] 97 stage-4 outlet connection

[0110] 100 tubing 1-2

[0111] 101 tubing 2-3

[0112] 102 tubing 3-4

[0113] General Description

[0114] A preferred embodiment of the portable air compressor of the present invention is illustrated in the attached drawings. The 4-stage diaphragm compressor consists mainly of the following parts. It mainly consists of a motor 70, which is positioned so that its motor shaft 71 points vertically downward, and four cylinder-piston assemblies that are positioned in the horizontal planes. The cylinder piston-assemblies are stacked on top of each other in the following order, at the bottom the stage-1 cylinder-piston assembly is positioned, and on top of it and positioned 180 degrees from it the stage-2 cylinder-piston assembly is positioned. On top of the stage-2 cylinder-piston assembly and positioned 90 degrees from it, the stage-3 cylinder-piston assembly is positioned. And on top of the stage-3 cylinder-piston assembly and positioned 180 degrees from it the stage-4 cylinder-piston assembly is positioned.

[0115] The cylinder-piston assemblies are shaped like a cylinder, which have an outer surface which is flat and on which the inlet connection and the outlet connection are attached; a side surface, which is round; and an inner surface, which is flat and has a large hole at its center, through which a piston can move in and out. Each cylinder-piston assembly has a diaphragm that is moved by a piston in and out so as to increase and decrease the volume in its cylinder chamber. In order to control the airflow into and out of a cylinder chamber each cylinder-piston assembly has two valves 55. One valve 55 is used as the inlet valve, used to control the flow through the inlet connection. And the other valve 55 is used as the outlet valve, used to control the flow through the outlet connection. The inlet valves are attached so that they only allow air to enter a cylinder chamber, and the outlet valves are attached so that they only allow air to exit a cylinder chamber. At the suction stage of a cylinder-piston assembly, that's when its piston pulls its diaphragm in so as to increase the volume in that cylinder chamber, only the inlet valve allows air to enter the cylinder chamber. And at the compression stage, that's when the piston pushes the diaphragm out so as to reduce the volume in that cylinder chamber, only the outlet valve allows air to exit the cylinder chamber, so that the compressed air can only escape through the outlet connection. For the stage-1 cylinder-piston assembly, its inlet connection, stage-1 inlet connection 90, is exposed to ambient air, so that during its suction stage, only ambient air is allowed to enter its cylinder chamber. And the stage-1 cylinder-piston assembly outlet connection, stage-1 outlet connection 91, is connected to the stage-2 cylinder-piston inlet connection, stage-2 inlet connection 92, so that during its compression stage all of the compressed air is directed to the stage-2 cylinder chamber, which volume is less than that of the stage-1 cylinder chamber. For the stage-2 cylinder-piston assembly, during its suction stage only the compressed air from the stage-1 cylinder chamber is allowed to enter its cylinder chamber. The outlet connection of the stage-2 cylinder-piston assembly, stage-2 outlet connection 93, is connected to the inlet connection of the stage-3 cylinder-piston assembly, stage-3 inlet connection 94, so that during its compression stage, all of the stage-2 compressed air is directed to the stage-3 cylinder chamber, which volume is less than that of the stage-2 cylinder chamber. For the stage-3 cylinder-piston assembly, during its suction stage only the compressed air from the stage-2 cylinder chamber is allowed to enter its cylinder chamber. The outlet connection of the stage-3 cylinder-piston assembly, stage-3 outlet connection 95, is connected to the inlet connection of the stage-4 cylinder-piston assembly, stage-4 inlet connection 96, so that during its compression stage, all of the stage-3 compressed air is directed to the stage-4 cylinder chamber, which volume is less than that of the stage-3 cylinder chamber. For the stage-4 cylinder-piston assembly, during its suction stage only the compressed air from the stage-3 cylinder chamber is allowed to enter its cylinder chamber. The outlet connection of the stage-4 cylinder-piston assembly, stage-4 outlet connection 97, can be connected to the device that utilizes the pressurized air.

[0116] Furthermore, the stage-1 and stage-2 pistons, piston 1 15 and piston 2 25, are mounted on a bottom cam 50; and the stage-3 and stage-4 pistons, piston 3 35 and piston 4 45, are mounted on a top cam 50. The top cam 50 and the bottom cam 50 are keyed to a motor shaft 71 so that the rotation of the motor shaft 71 causes the cams 50 to rotate. And since the portion of the cams 50 on which the pistons are mounted are eccentric relative to the motor shaft 71, the rotation of the cams 50 cause the pistons to move radially in and out relative to the motor shaft 71. In addition, to a portion of cam 50 that is centric relative to motor shaft 71, a flywheel half 1 51 and a flywheel half 2 52 are attached. Here flywheel half 1 51 is identical to flywheel half 2 52, except for having an extension, which is used to cancel the centrifugal force due to the eccentricity of the cam 50. Also in order to prevent the compressor from overheating a fan 58 is mounted below the bottom cam 50 on shaft 71.

[0117] In order to hold the parts of the 4-stage diaphragm compressor in place a casing assembly is used. The casing assembly consists mainly of a bottom casing block 80 and a top casing block 81. The bottom casing block 80 is shaped like the bottom halve of an empty box, having four side walls and a bottom wall. At the bottom wall of the bottom casing block two bottom casing bearings 57 are pressed in. In addition, there are four holes for airflow purposes at the bottom wall of the bottom casing block 80. The top casing block 81 is shaped like the top halve of an empty box, having a top wall and four side walls. At the top wall of the top casing block 81 a motor cavity, in which the motor 70 can be tightly inserted exist. Below the motor cavity, there are two top casing bearings 56 pressed into the top casing block 81. In the assembled stage, the bottom casing block 80 is mated with the top casing block 81 such that a solid structure is formed. In the assembled stage, the motor shaft 70 is inserted through the top casing bearing 56 and through the bottom casing bearing 57. And the face of motor 70 is pressed into the motor cavity of the top casing block 81. Because of the shape of the face of motor 70 and the shape of the motor cavity, relative rotation between the motor 70 and the top casing block 81 is prevented. The motor shaft 71, the cams 50, the flywheel halves 1 51, and the flywheel halves 2 52, are located in the empty space created between the side walls of the bottom casing block 80 and the side walls of the top casing block 81. The side surfaces of the cylinder assemblies are clamped together by the side walls of the bottom casing block 80 and the side walls of the top casing block 81. The side walls of the bottom casing block 80 and the side walls of the top casing block 81 have four circular arc shaped cavities, each circular arc shaped cavity matches the side surface of the cylinder-piston assembly that is clamped by those side walls. In addition, at the top and at the bottom of the circular shaped cavities in the vertical walls, square shaped openings exist. And to the left and to the right of the circular shaped cavities, a square shaped opening is formed. The square shaped openings are used to allow hot air from the casing assembly to escape. Also in order to prevent the cylinder assemblies from moving towards motor shaft 71, at the inner end of each circular arc shaped cavity an inner surface exist. The inner surfaces are shaped so that they are in contact with the inner surfaces of the cylinder assembly positioned there, and are large enough to allow the pistons to freely move in and out of their cylinder assembly. And in order to prevent the cylinder assemblies from moving away from the motor shaft 70, each cylinder assembly has a casing cover. Each casing cover has two holes, one hole to attach the inlet connection, and another hole to attach the outlet connection. In addition, each casing cover has square shaped openings that roughly match the square shaped openings of the top casing block 81 and the bottom casing block 80.

[0118] Mechanical Parts-FIGS 1A-1C

[0119] The arrangement for the stage-1 cylinder-piston assembly are the following, here a diaphragm 1 11 is placed on top of cylinder body 1 10. Cylinder body 1 10 is shaped like a ring, hence there is a section of diaphragm 1 11 that is not in contact with the cylinder body 1 10. The section of diaphragm 1 11 in contact with cylinder body 1 10, will be referred to as the fixed section, and the section of diaphragm 1 11 not in contact with cylinder body 1 10 will be referred to as the free section. In addition cylinder body 1 10 has several threaded holes, which will be used to keep the parts of the stage-1 cylinder assembly together by the use of cylinder cap screws 62. In order to attach diaphragm 1 11 to the piston assembly that moves it, a portion of the free section of diaphragm 1 11 is clamped by a circular attachment surface of piston 1 15 and piston cap 1 16 by the use of a piston cap screw 60. In addition, diaphragm 1 11 also has bolt holes that are aligned with the threaded holes of cylinder body 1 10, through which the cylinder cap screws 62 can be inserted. Cylinder head 1 12 is shaped like a cup, with its open end facing the outer surface of the fixed section of diaphragm 1 11. The chamber of cylinder head 1 12 is shaped as to allow sufficient movement for diaphragm 1 11, but minimizes any unnecessary space. The spaced formed by the chamber of cylinder head 1 12 and the free surface of diaphragm 1 11 is the cylinder chamber of the stage-1 cylinder-piston assembly. Furthermore, the closed end of cylinder head 1 12 has an inlet hole and an outlet hole. Near the inlet hole of cylinder head 1 12 a valve cavity, in which a valve 55, used as the inlet valve, and the head of its valve pin 61 will be placed exist. The shape of a valve 55 is like the middle cross section of an upright egg, where the top circular arc shaped end is smaller than the bottom circular arc shaped end. A hole used to insert the valve pin 61 exists at the smaller end of the valve 55. The valve cavity has sufficient depth to allow the valve 55 to sufficiently open. Its is also recommended that the valve is made out of a magnetic material, so to improve its sealing properties when it is not active. And near the outlet hole of cylinder head 1 12 a pin hole used to insert a valve pin 61 exist. Also a valve 55, used as the outlet valve, is attached to the outer surface of the cylinder head 1 12. Valve 55 is attached to the outer surface of cylinder head 1 12, such that its larger end is completely covering the outlet hole. Then a valve pin 61 is pressed in through the hole of valve 55 and the pin hole of cylinder head 1 12, until valve 55 is pressed towards the outer surface of cylinder head 1 12 by the head of valve pin 61. In addition, cylinder head 1 12 also has bolt holes that align and are of the same size as the bolt holes of diaphragm 1 11. On the outer surface of cylinder head 1 12 a valve gasket 1 13, used to seal that gap between cylinder head 1 12 and valve cover 1 14, is placed. The valve gasket 1 13 has cut-out openings for valve 55, used as the inlet valve, and the valve 55, used as the outlet valve. Also, valve gasket 1 13 has bolts holes that are aligned and are of the same size as the bolt holes of cylinder head 1 12. On the outer surface of valve gasket 1 13, a valve cover 1 14 is placed. Valve cover 1 14 is shaped like a round plate that has an inlet hole and an outlet hole. On top of the inlet and outlet holes are threaded holes, used to attach the stage-1 inlet connection 90 and the stage-1 outlet connection to valve cover 1 14. Also, near the inlet hole of valve cover 1 14, a pin hole used to press in a valve pin 61 exist. And at the inner surface of valve cover 1 14, near the outlet hole of valve cover 1 14 a valve cavity for the valve 55 used as the outlet valve, and its valve pin 61 head exist. This cavity is shaped in the same manner as the valve cavity in cylinder head 1 12. In addition, a valve 55, used as the inlet valve, is attached to the inner surface of the valve cover 1 14. Valve 55 is attached such that its larger end is completely covering the inlet hole. Then a valve pin 61 is pressed in through the hole of inlet valve 55 and through the pin hole of the valve cover 1 14 until the head of valve pin 61 presses the valve 55 towards the inner surface of the valve cover 1 14. Furthermore, valve cover 1 14 has bolt holes that are aligned with and are of the same size as the bolt holes in valve gasket 1 13. In order to hold the parts of the cylinder assembly together cylinder cap screws 62 are inserted through the valve cover 1 14, the valve gasket 1 13, the cylinder head 1 12, the diaphragm 1 11, and screwed into the threaded holes of cylinder body 1 10.

[0120] As can be seen in FIGS. 1A, 1B, and 1C, the stage-2 cylinder-piston assembly, the stage-3 cylinder-piston assembly, and the stage-4 cylinder-piston assembly are identical to the stage-1 cylinder-piston assembly, except that the diameters of the cylinder chambers for the stage-2, stage-3, and stage-4 cylinder-piston assemblies are smaller than the diameter of the stage-1 cylinder-piston assembly. Here, the cylinder chamber diameter of the stage-3 cylinder-piston assembly is smaller than that of the stage-2 cylinder-piston assembly, and the cylinder chamber diameter of the stage-4 cylinder-piston assembly is smaller than that of the stage-3 cylinder-piston assembly. The decrease in a cylinder chamber diameter also results in the decrease of the outside diameter of the cylinder assembly. Hence the stage-2, 3, and 4 cylinder-piston assembly parts are identical to the stage-1 cylinder-piston assembly parts except for having a smaller inside diameter and a smaller outside diameter. For the stage-2 cylinder-piston assembly cylinder body 1 10 is replaced with cylinder body 2 20, diaphragm 1 11 is replaced with diaphragm 2 21, piston 1 15 is replaced with piston 2 25, piston cap 1 16 is replaced with piston cap 2 26, cylinder head 1 12 is replaced with cylinder head 2 22, and valve cover 1 14 is replaced with valve cover 2 24, stage-1 inlet connection 90 is replaced with stage-2 inlet connection 92, and stage-1 outlet connection 91 is replaced with stage-2 outlet connection 93. For the stage-3 cylinder-piston assembly cylinder body 1 10 is replaced with cylinder body 3 30, diaphragm 1 11 is replaced with diaphragm 3 31, piston 1 15 is replaced with piston 3 35, piston cap 1 16 is replaced with piston cap 3 36, cylinder head 1 12 is replaced with cylinder head 3 32, valve cover 1 14 is replaced with valve cover 3 34, stage-1 inlet connection 90 is replaced with stage-3 inlet connection 94, and stage-1 outlet connection 91 is replaced with stage-2 outlet connection 95. For the stage-4 cylinder-piston assembly cylinder body 1 10 is replaced with cylinder body 4 40, diaphragm 1 11 is replaced with diaphragm 4 41, piston 1 15 is replaced with piston 4 45, piston cap 1 16 is replaced with piston cap 4 46, cylinder head 1 12 is replaced with cylinder head 4 42, and valve cover 1 14 is replaced with valve cover 4 44 stage-1 inlet connection 90 is replaced with stage-4 inlet connection 96, and stage-1 outlet connection 91 is replaced with stage-4 outlet connection 97. The parts for the stage-2 cylinder-piston assembly, the stage-3 cylinder-piston assembly, and the stage-4 cylinder-piston assembly, as mentioned above, are assembled in the same manner as are the parts for the stage-1 cylinder-piston assembly as described in the previous paragraph.

[0121] Each piston of the cylinder-piston assembly is shaped like a long bar that has a pivot hole near one end and a circular attachment surface at its other end. A piston bearing 54 is tightly pressed in into the pivot hole of each piston, as to prevent any axial movements between the piston and the piston bearing 54. The circular attachment surfaces of the pistons are attached to their respective diaphragms. And in order to move the pistons, the piston bearings 54 are mounted on a cam 50, which converts the rotation of motor shaft 71 into movements that pull and push the pistons and hence the diaphragms connected to them in and out. Piston bearing 54 of piston 1 15 and piston bearing 54 of piston 2 25 are mounted on the bottom cam 50 and piston bearing 54 of piston 3 35 and piston bearing 54 of piston 4 45 are mounted on the top cam 50. A cam 50 consists of two shapes, a shape 1 and a shape 2, which are both shaped like cylinders. The piston bearings 54 of the pistons are inserted into shape 1, while shape 2 will be used to attach a flywheel half 1 51 and a flywheel half 2 52. Also cam 50 has an axial hole that goes through shape 1 and shape 2. Through the axial hole of cam 50, motor shaft 71 will be slidably inserted. When slid onto motor shaft 71, shape 1 is eccentric relative to motor shaft 71, so that its center axis is parallel but offset relative to the axis of rotation of motor shaft 71. This eccentricity moves the pistons radially in and out relative to motor shaft 71 as it is rotating. Also at one end of shape 1, a circular groove for a cam retaining ring 65 exists. At the other end of shape 1, a shape 2 exists. When cam 50 is slid onto motor shaft 71, shape 2 is centric relative to motor shaft 71, so that its center axis is positioned at the center of rotation of motor shaft 71. The diameter of shape 2 is larger than the diameter of shape 1 as to provide a shoulder for the pistons that are slid into shape 1. In addition, shape 2 has three radially positioned threaded holes. The threaded hole closest to shape 1 is used to rotatably fix cam 50 to motor shaft 71, by the use of a cam set screw 63. The other two threaded holes are positioned opposite from each other and are used to attach a flywheel half 1 51 and a flywheel half 2 52 to cam 50. Flywheel half 1 51 and flywheel half 2 52 are shaped like halves of a cylinder that have an inner diameter that tightly fits onto shape 2 of cam 50. In order to attach flywheel half 1 51 and flywheel half 2 52 to cam 50, flywheel half 1 51 and flywheel half 2 52 each have a radial threaded hole through which a flywheel screw 64 can be screwed in. Also, flywheel half 1 51 is shaped exactly like flywheel half 2 52, except for having an extension, which is used to counter-balance the eccentricity of shape 1. In order to reduce vibrations due to the eccentricity of shape 1, the extension of flywheel half 1 51 is positioned adjacent to shape 1 so as to minimize the distance between shape 1 the counter-balancing extension of flywheel half 1 51.

[0122] According to its diameters, the motor shaft 70, used to rotate the cams 50 can be divided into three different sections, the top section, which is very short, the middle section, which has a smaller diameter than the top section but is the longest, and the bottom section, which has a smaller diameter than the middle section. The shoulder created between the top and middle section is used as a resting surface for shaft 71 on the top casing bearings 56. The diameter of the top section is small enough so that shaft 71 only rests on the inner ring of top casing bearing 57. Here the inner ring of a bearing is the ring of a bearing that is free to rotate relative to the outer ring that is fixed relative to the top casing block 81. The middle section of motor shaft 70 is used to attach the cams 50 and the fan 58. It has a top threaded hole, used to rotatably fix the top cam 50 to the motor shaft, and a bottom threaded hole, used to rotatably fix the bottom cam 50 to the motor shaft. The fan 58 is attached to motor shaft 70 by friction. Into the bottom shape of motor shaft 71, the bottom casing bearings 57 are inserted. Near the end of the bottom shape of motor shaft 71 a retaining ring groove exists, which is positioned so that the shoulder between the middle shape and the bottom shape of motor shaft 71 and the shaft retaining ring inserted into the retaining ring groove of motor shaft 71 tightly clamp the bottom casing bearings 57.

[0123] In its assembled state, the top cam 50 is mounted on the upper portion of motor shaft 71, and is positioned so that its shape 2 is above its shape 1. This cam 50 is then fixed to motor shaft 71 by a cam set screw 63 that is threaded through the designated threaded hole in cam 50 and the top threaded hole in motor shaft 71. Then flywheel half 1 51 and flywheel half 2 52 are attached to shape 2 of this cam 50, each by a cam set screw 63 that threads through them and the designated threaded holes in shape 2 of cam 50. Then the following items are inserted into shape 1 of this cam 50 in the following order, spacer 53, piston bearing 54 of piston 4 45, spacer 53, piston bearing 54 of piston 3 35, spacer 53. The items above are then held in place by a cam retaining ring 65 which is fitted into the designated groove in shape 1 of the cam 50. The cam 50 mounted on the lower portion of motor shaft 71 is mounted to motor shaft 71 in a way such that its shape 1 is above its shape 2. Like the top cam 50 mounted on top of it, this cam 50 is also fixed to motor shaft 71 by a cam set screw 63 that is threaded through the designated threaded hole in cam 50 and the bottom threaded hole in the motor shaft 71. The following items are slid in shape 1 of this cam 50 in the following order, spacer 53, piston bearing 54 of piston 1 15, spacer 53, piston bearing 54 of piston 2 25, spacer 53. As for the top cam 50, the items above are then held in place by a cam retaining ring 65, which is fitted into the designated groove in shape 1 of this cam 50. A flywheel half 1 51 and a flywheel half 2 52 are attached to shape 2 of this cam 50, each by a cam set screw that threads through them and the designated threaded holes in shape 2.

[0124] Casing-FIGS. 2A-2F, 3A-3F, 4A-4E

[0125] A casing assembly is used to properly fix the positions of the cylinders-piston assemblies and motor 70, and to provide proper support for motor shaft 71. The casing assembly consist of a bottom casing block 80, two bottom casing block bearings 57, a top casing block 81, two top casing block bearings 56, a front cover 82, a right cover 83, a back cover 84, a left cover 85, sixteen cover screws 67, four casing cap screws 68, and four casing nuts 69. It is recommended that the bottom casing block 80, the top casing block 81, and the casing covers are made out of ABS plastic.

[0126] The bottom casing block 80, see FIGS. 2A to 2F, is a molded plastic part that is shaped like the lower portion of an empty box that is cut in half. Like the lower portion of an empty box that is cut in half it has a bottom wall, a front wall, a back wall, a right wall, and a left wall. Here, the height of the front wall is lower than the height of the back wall, and the right wall and the left wall have a middle portion that higher than the front wall and the back wall. The front wall is used to support the stage-1 cylinder assembly. The height of the front wall is slightly less then the distance from the bottom of the lower casing block to the center of stage-1 cylinder assembly. The front wall has an outer surface and an inner surface. The outer surface is used to support the side surfaces of the stage-1 cylinder assembly, which is the round surface of the stage-1 cylinder assembly. The outer shape of the front wall has a rectangular shape that has four cut-out section. The first cut-out section is a circular arc, which center is located slightly above the middle of the top end of the front wall. The circular arc is shaped so that it can provide a tight resting surface for the side surface of the stage-1 cylinder assembly. The next cut-out section, which is located at the middle of the front wall and directly below the circular arc cut-out, has a rectangular shape, and is narrower than the width of the circular arc cut-out and extends downward of the circular arc cut-out. The next cut-out sections are located at the top end of the front wall, and directly to the left and right of the circular arc cut-out. These cut-out sections also have a rectangular shape. The rectangular shape cut-outs are used to allow hot air from the casing assembly to escape. The inner surface of the front wall is shaped exactly like its outer surface, except that its circular arc cut-out is smaller in diameter than that of its outer surface. Because of its smaller circular arc cut-out, the inner surface of the front wall is in contact with a portion of the inner surface of the stage-1 cylinder assembly. This prevents the stage-1 cylinder assembly from moving towards motor shaft 71. The smaller circular arc cut-out of the inner surface is not used as a resting place for the side surfaces of the stage-1 cylinder assembly, but is used to allow piston 1 15 to freely move diaphragm 1 11. The back wall is used to support the stage-2 cylinder assembly and is shaped in the same manner as the front wall.

[0127] The left wall is used to support the stage-4 cylinder assembly. The left wall consists of three main shapes the left shape, the middle shape, and the right shape. The height of the left shape is the same as the height of the back wall and its width is slightly larger than the thickness of the back wall. The height of the right shape is the same as the height of the front wall and its width is slightly larger than the thickness of the front wall. The middle shape is higher than the right shape and the left shape such that it can properly support the stage-4 cylinder assembly, which is positioned above the stage-1 cylinder assembly and the stage-2 cylinder assembly. The outer surface of the middle shape is used to support the side surface of the stage-4 cylinder assembly, which is the round surface of the stage-4 cylinder assembly. At the middle of the top end of the middle shape a circular arc cut out, which is used to tightly support the stage-4 cylinder assembly exists. The center of the circular arc cut-out is located above the top end of the middle shape, such that rectangular gaps to the left and to the right of the circular arc cut-out are formed when the bottom casing block 80 is mated with the top casing block 81. In addition, a rectangular cut-out that is narrower than the width of the circular arc cut-out and extends downward of the circular arc cut-out exists. The rectangular cut-out and the rectangular gaps are used to allow the hot air from the casing assembly to escape. The inner surface is shaped exactly like its outer surface, except that it has a circular arc cut-out that is smaller in diameter than that of its outer surface. Because of its smaller circular arc cut-out, the inner surface of the right wall is in contact with a portion of the inner surface of the stage-4 cylinder assembly. This prevents the stage-4 cylinder-piston assembly from moving towards motor shaft 71. The smaller circular arc cut-out of the inner surface is not used as a resting place for the side surfaces of the stage-4 cylinder assembly, but is used to allow piston 4 45 to freely move diaphragm 4 41.

[0128] The bottom wall of the bottom casing block 80 can be divided into two sections, which are the rim section and the inner section. The rim section is the section of the bottom wall that is covered by the vertical walls, which are the front, back, right side, and left side walls. The inner section of the bottom wall is the section of the bottom wall that is not covered by the front, back, right side, and left side walls. Near each corner of the rim section four hexagonal cavities, which are slightly larger than the casing nuts 69, exist. Also at the top end of each hexagonal cavity, a bolt hole that is centric to the hexagonal cavity and goes through the entire height of bottom casing block 80 exists. At the center of the inner section two concentric holes exist. The upper concentric hole has a diameter that is slightly larger than the diameter of the motor shaft 71, but is smaller then the diameter of the bottom casing bearings 57. The lower concentric hole has a diameter that is slightly smaller than the diameter of the bottom casing bearings 57. Into the lower concentric hole, two bottom casing ball bearings 57 are pressed in so as to prevent any axial movements between the bottom casing bearing 57 and the bottom casing block 80. In addition, the inner section of the bottom wall also has four holes used to allow ambient air to enter the casing assembly. Each hole is located between a vertical wall and the two concentric holes at the center of the inner section. A bottom cavity in the shape of the inner section also exists at the bottom surface of the bottom wall. The bottom cavity is deep enough so that when the compressor is in its assembled state, motor shaft 71 does not extend beyond the bottom end of the bottom casing block 80.

[0129] The top casing block 81, see FIGS. 3A-3E, is a molded plastic part that is shaped like the upper portion of an empty box that is cut in half. Like the upper portion of an empty box that is cut in half, it has a top wall, a front wall, a back wall, a right wall, and a left wall. Here, the depth of the front wall is greater than the depth of the back wall. And the right wall and the left wall each have a middle shape, which depth is less than the depth of the front wall and the back wall. The front wall is used to tightly embrace a portion of the upper surface of the stage-1 cylinder assembly. The depth of the front wall is slightly less then the distance from the top surface of the top casing block 81 to the center of a circular arc, used to support the side surface of the stage-1 cylinder assembly, which is the round surface of the stage-1 cylinder assembly. The front wall has an outer surface and an inner surface. The outer surface is used to support the side surfaces of the stage-1 cylinder assembly. The outer surface of the front wall has a rectangular shape that has four cut-out section. The first cut-out section is a circular arc, which center is located slightly below the middle of the bottom end of the front wall. The circular arc is shaped so that it can provide a tight clamping surface for the side surface of the stage-1 cylinder assembly. The next cut-out section, which is located at the middle of the front wall and directly above the circular arc cut-out, is a rectangular shape, which is narrower than the width of the circular arc cut-out and extends upwards of the circular arc cut-out. In addition, there are cut-out sections that are located at the bottom end of the front wall, and directly to the left and right of the circular arc cut-out. These cut-out sections also have a rectangular shape. The rectangular shape cut-out sections are used to allow hot air from the casing assembly to escape. The inner surface of the front wall is shaped exactly like its outer surface, except that its circular arc cut-out is smaller in diameter than that of its outer surface. Because of its smaller circular arc cut-out, the inner surface of the front wall is in contact with a portion of the inner surface of the stage-1 cylinder assembly. This prevents the stage-1 cylinder assembly from moving towards motor shaft 71. The smaller circular arc cut-out of the inner surface is not used as a resting place for the side surfaces of the stage-1 cylinder assembly, but is used to allow piston 1 15 to freely move diaphragm 1 11. The back wall is used to support the stage-2 cylinder assembly and is shaped in the same manner as the front wall.

[0130] The left wall is used to support stage-4 cylinder assembly. The left wall consists of three main shapes the left shape, the middle shape, and the right shape. The left shape has the same depth as the back wall, and its width is the same as the thickness of the back wall. The right shape has the same depth as the front wall and its width is the same as the thickness of the front wall. The depth of the middle shape is less than that of the right shape and that of the left shape such that it can properly support the stage-4 cylinder assembly, which is positioned at a smaller depth than the stage-1 cylinder assembly and the stage-2 cylinder assembly. The outer surface of the middle shape is used to tightly wrap around the side surface of the stage-4 cylinder assembly, which is the round surface of the stage-4 cylinder assembly. At the middle of the bottom end of the middle shape a circular arc cut-out, which is used to tightly wrap around the stage-4 cylinder exists. The center of the circular arc cut-out is located below the bottom end of the middle shape, such that rectangular gaps to the left and to the right of the circular arc cut-out are formed when the bottom casing block 80 is mated with the top casing block 81. In addition, a rectangular cut-out that is narrower than the width of the circular arc cut-out and extends upwards of the circular arc cut-out exists. The rectangular cut-out extends up to the bottom surface of the top wall. This is necessary since this cut-out section is also used to screw in the cam set screw 63, used to attach the top cam 50 to motor shaft 70. The rectangular cut-out and the rectangular gaps are used to allow the hot air from the casing assembly to escape. The inner surface is shaped exactly like its outer surface, except that it has a circular arc cut-out that is smaller in diameter than that of its outer surface. Because of its smaller circular arc cut-out, the inner surface of the right wall is in contact with a portion of the inner surface of the stage-4 cylinder assembly. This prevents the stage-4 cylinder assembly from moving towards motor shaft 71. The smaller circular arc cut-out is not used as a resting place for the side surfaces of the stage-4 cylinder assembly, but is used to allow piston 4 45 to freely move diaphragm 4 41.

[0131] The top wall of the top casing block 81 can be divided into two sections, which are the rim section and the inner section. The rim section is the section of the top wall that is covered by the vertical walls, which are the front, back, right and left walls. The inner section of the top wall is the section of the top wall that is not by the vertical walls. Near each corner of the rim section a cylindrical cavity, which is slightly larger than the head of the casing cap screw 68 exist. At the bottom end of each cylindrical cavity a bolt hole that is centric to the cylindrical cavity and goes through the entire depth of the upper casing block 81 exist. At the center of the inner section of a motor cavity which axial cross section is of the same shape as that of the face of motor 70 exist. The axial cross section of the motor cavity consists of a circular shape, which is centric to the center of the top wall and has a diameter that is slightly larger than the diameter of the face of motor 70; and two rectangular extensions that extend from the circular shape towards the front wall and the back wall, which have a width that is slightly smaller than that of the rectangular extensions of the face of motor 70. Since the width of the extensions of the motor cavity is slightly smaller than that of the face of motor 70, the extensions of the motor cavity tightly grip the extensions of the face of motor 70, so as to prevent motor 70 from rotating relative to the top casing block 81. At the center of the motor cavity two concentric holes exist. The upper concentric hole is slightly smaller than the diameter of the top casing bearings 56. The lower concentric hole is slightly larger than the diameter of the motor shaft 71, but smaller than the diameter of the top casing bearings 56. The top casing bearings 56 are pressed into the upper concentric hole so as to prevent any axial movements between the top casing block 81 and the top casing bearings 56.

[0132] Furthermore, in order to prevent the cylinder assemblies from moving away from motor shaft 71, cover plates are used. Here, a front cover plate 82 is used for the stage-1 cylinder assembly, a back cover plate 84 is used for the stage-2 cylinder assembly, a right cover plate 85 is used for the stage-3 cylinder-piston assembly, and a left cover plate 86 is used for the stage-4 cylinder assembly. Each cover plate has a square outer surface, which has a screw hole at each corner. Also, each cover plate has an inlet hole, through which the inlet connection of a cylinder assembly can be inserted; and an outlet hole, through which the outlet connection of a cylinder assembly can be inserted. In addition, at the middle of each side of the cover plate, a rectangular cut-out section exists. These rectangular cut-out sections are used to allow the hot air in casing assembly to escape.

[0133] Tubing-FIGS. 5A-5E

[0134] In order to properly direct the air between the cylinder assemblies tubing are used. A tubing 1-2 100 is used to connect the stage-1 outlet connection 91 of the stage-1 cylinder assembly to the stage-2 inlet connection 92 of the stage-2 cylinder-piston assembly. A tubing 2-3 101 is used to connect the stage-2 outlet connection 93 of the stage-2 cylinder piston assembly to the stage-3 inlet connection 94 of the stage-3 cylinder assembly. And a tubing 3-4 102 is used to connect the stage-3 outlet connection 95 of the stage-3 cylinder assembly to the stage-4 inlet connection 96 of the stage-4 cylinder piston assembly. It is recommended that the inside diameters of the tubing are as small as possible without generating excess back pressures. And it is also recommended that for each tubing, the bending radius of the tubing is at least 1.5 its outside diameter.

[0135] Assembly Procedure-FIGS. 1A-1C, 4A-4E, 5A-5E

[0136] In order to assemble the compressor, first the cylinder-piston assemblies are assembled as discussed above. Then a flywheel halves 1 51 and a flywheel halves 2 52 are attached to the shape 2 of the top cam 50 and to the shape 2 of the bottom cam 50, by flywheel screws 64 that are threaded through the flywheel halves and the designated threaded holes in the shapes 2 of the cams 50. Then motor shaft 71 is inserted through the top casing bearings 56 of the top casing block 81, until the shoulder between the top section and the middle section of motor shaft 71 rest on the inner ring of top casing bearing 71. Next the top cam 50, with its shape 2 positioned on top, is inserted into motor shaft 71. Then the rectangular cut-out above the circular arc cut out of the left wall of the top casing block 81 is used to screw in a cam set screw 63 through the designated threaded hole in the top cam 50 and the top threaded hole of motor shaft 71. After that, the following items are slid into the shape 1 of the top cam 50, which is eccentric, in the following order, spacer 53, piston bearing 54 of piston 4 45, spacer 53, the piston bearing 54 of piston 3 35, spacer 53. And a cam retaining ring 65 is inserted in the designate groove in shape 1 of cam 50 as to prevent the inserted items from sliding out. Next the following items are slid into the shape 1 of the bottom cam 50, which is eccentric, in the following order, spacer 53, piston bearing 54 of piston 1 15, spacer 53, the piston bearing 54 of piston 2 25, spacer 53. And a cam retaining ring 65 is inserted in the designate groove in shape 1 of cam 50 as to prevent the inserted items from sliding out. Then the bottom cam 50, with its shape 2 on the bottom, is inserted into motor shaft 71, and a cam set screw 63 is screwed into the designated threaded hole of the bottom cam 50 and the bottom threaded hole of motor shaft 71. Next the fan 58 is attached to motor shaft 71, so that it is positioned slightly below the bottom cam 50. Then the top casing block 81 is mated with the bottom casing block 80. Here first, motor shaft 71 is slid through the bottom casing bearings 57 of bottom casing block 80. Then the bottom casing block 80 is positioned so that it vertical walls form a straight surface with the vertical walls of the top casing block 81. Then the casing nuts 69 are inserted into the hexagonal cavity of the bottom casing block 80, and the casing cap screws 68 are inserted through the bolt holes of the top casing block 81 and the bottom casing block 80 and tightened. Next the cover plates are attached to their surfaces such that their inlet holes and their outlet holes are centered to the inlet holes and outlet holes of their respective valve covers. And finally, the tubing connections and tubing are attached as shown in FIGS. 5A-5E

[0137] FIGS. 6-7-Alternative Embodiments

[0138] A variation for the diaphragm that can be used for the 4-stage diaphragm compressor is shown in FIG. 6. Here a piston pin 60A, which has a pin hole, is molded into the alternate diaphragm 11A, so as to eliminate the need of the piston cap and the piston cap screw 60. The alternate diaphragm 11A is then attached to an alternate piston 15A, which has a hole through which piston pin 60A can be inserted and a pin hole, which is positioned so that a piston pin 2 60B can be tightly inserted through the piston pin 60A pin hole and the pin hole of said alternate piston 15A.

[0139] Also in order to obtain more torque from the motor 70 a gearbox can be used as shown in FIG. 7. Here the motor 70 is attached to the input of the gearbox and the motor shaft 71 is attached to the output of the gearbox.

[0140] Advantage

[0141] From the description above, a number of advantages of my 4-stage diaphragm compressor become evident:

[0142] (a) The 4-stage diaphragm compressor has a higher pressure rating than currently available portable compressors.

[0143] (b) The 4-stage diaphragm compressor is smaller in size than currently available high pressure compressors, so that it can be made portable.

[0144] (c) Compared to reciprocating compressors the 4-stage diaphragm compressor has less frictional energy losses.

[0145] (d) Compared to currently available diaphragm compressors the 4-stage diaphragm compressor has a higher airflow and pressure rating.

[0146] Operation

[0147] In order to utilize the 4-stage diaphragm compressor, the operator turns on the motor 70, and directs the air from the outlet coupling of the 4-stage cylinder assembly to the device that utilizes the compressed air. Or the operator can also use the compressor as booster, by connecting the outlet of another compressor to the stage-1 inlet coupling 90.

[0148] Conclusion, Ramification, Scope

[0149] Accordingly, the reader will see that the 4-stage diaphragm compressor of this invention provides a compact portable device that can provide a large airflow at a high pressure. The portability and high pressure rating of this compressor opens-up endless possibilities where this compressor can be used. For example, this compressor can be carried in cars, such that in case of a flat tire, this compressor can be used to power a device that can partially lift the car and can be used to power devices that can unscrew the nuts of a wheel. Or as another example, this compressor can be used for painting or cleaning purposes.

[0150] Furthermore, the 4-stage diaphragm has the additional advantages in that

[0151] it permits the usage of devices requiring high pressures, in instances where a high pressure source is unavailable and in instances where it is inconvenient, if not impossible, to carry a regular size high pressure compressor;

[0152] it is more efficient than reciprocating compressors, because of the elimination of frictional energy losses generated between the inner walls of a cylinder and the piston rings;

[0153] it is easier to maintain than reciprocating compressors, because it is relatively easier to replace a worn diaphragm than it is to replace a worn piston ring;

[0154] Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example, the relative position of the cylinder-piston assemblies can be changed; the position of the motor can be changed, the eccentric cam 50 can be replaced with a crank-shaft, etc.

[0155] Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.