US3790310A

US3790310A - Fluid powered air compressor

Info

Publication number: US3790310A
Application number: US00252106A
Authority: US
Inventors: J Whelan
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1972-05-10
Filing date: 1972-05-10
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

A fluid powered air compressor including two interconnected pistons, each operatively associated with respective diaphragm air compressors. A control valve is provided to receive and direct pressurized fluid from an external source, the valve being spring biased to a normal position. In its normal position the valve directs the fluid to a first one of the pistons which moves in response thereto and pressurizes fluid flexing its associated air compressing diaphragm thereby pressurizing air that is discharged to a receiver. While the first piston is moving to pressurize air, the second piston moves to flex its associated air compressing diaphragm in a direction to draw air into its air chamber. Sufficient movement of the first piston in an air pressurizing direction opens a conduit connecting the externally supplied pressurized fluid to one end of the control valve in opposition to its spring biasing means. The control valve is moved by the pressurized fluid to a position directing the externally supplied pressurized fluid to the second piston. The second piston then moves flexing its associated air compressing diaphragm pressurizing air on the opposite side thereof which is discharged through an exhaust valve to the aforementioned receiver. At this time the first piston flexes its air compressing diaphragm drawing inlet air into its air chamber. After the second piston has moved a sufficient distance, the pressurized fluid is exhausted from the one end of the control valve allowing it to return to its normal position completing one cycle of operation. These cycles automatically continue as long as pressurized fluid is supplied to the control valve from an external source.

Description

United States Patent 1 Whelan Feb. 5, 1974 FLUID POWERED AIR COMPRESSOR James E. Whelan, Dayton, Ohio [73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: May 10, 1972 21 Appl. No.: 252,106

[75] Inventor:

[52] US. Cl 417/388, 91/290, 417/393,

[51] Int. Cl. F04b 9/10, F04b 35/02 [58] Field of Search... 417/383, 388, 389, 395, 404, 417/393; 91/290 [56] References Cited Primary Examiner-Carlton R. Croyle Assistant ExaminerRic hard Sher Attorney, Agent, or Firm-Charles R. Engle [57] ABSTRACT A fluid powered air compressor including two interconnected pistons, each operatively associated with respective diaphragm air compressors. A control valve 7 is provided to receive and direct pressurized fluid from an external source, the valve being spring biased to a normal position. In its normal position the valve directs the fluid to a first one of the pistons which moves in response thereto and pressurizes fluid flexing its associated air compressing diaphragm thereby pressurizing air that is discharged to a receiver. While the first piston is moving to pressurize air, the second piston moves to flex its associated air compressing diaphragm in a direction to draw air into its air chamber. Sufficient movement of the first piston in an air pressurizing direction opens a conduit connecting the externally supplied pressurized fluid to one end of the control valve in opposition to its spring biasing means. The control valve is moved by the pressurized fluid to a position directing the externally supplied pressurized fluid to the second piston. The second piston then moves flexing its associated air compressing diaphragm pressurizing air on the opposite side thereof which is discharged through an exhaust valve to the aforementioned receiver. At this time the first piston flexes its air compressing diaphragm drawing inlet air into its air chamber. After the second piston has moved a sufficient distance, the pressurized fluid is exhausted from the one end of the control valve allowing it to return to its normal position completing one cycle of operation. These cycles automatically continue as long as pressurized fluid is supplied to the control valve from an external source.

2 Claims, 1 Drawing Figure RECEIVER PAIENTEDFEB 51w 3.790.310

RECEIVER SOURCE PRESSURE FLUID SOURCE RESERVOIR This invention related to a fluid powered air compressor and more particularly to a fluid powered air compressor having first and second interconnected pistons moved to simultaneously flex a diaphragm in one air compressor compressing air while flexing a diaphragm in another air compressor to draw air in so that the oscillatory movement of the interconnected pistons pressurizes and draws inlet air into respective air compressor assemblies associated with each piston during such movement.

Heretofore, many complicated fluid actuated air compressor assemblies have been developed. These assemblies have necessarily included a number of relatively movable components which are either motor driven or are mechanically driven resulting in frictional loses decreasing the efficiency thereof. Also it is known to use two diaphragms, each being located in an accumulator in a fluid system cycling compressed air to and from a Stirling cycle engine as is' disclosed in the US. Pat. to Brades 3,496,879, filed Jan. 10, 1968 and issued Feb. 24, 1970. Accordingly, it is a purpose of this invention to provide a fluid powered air compressor assembly that takes advantage of an available source of fluid under pressure, suchas that present in a vehicle power steering syste. The air compressor assembly receives the pressurized fluid from the external source through a control valve that is a slave to the movement of the interconnected pistons. The control valve is automatically positioned directing this fluid in response to movement of interconnected pistons to alternately supply the fl'uid to respective diaphragm air compressors each associated with one of the interconnected pistons providing an efficient means of supplying compressed air. The subject fluid powered air compressor has parcontrol valve biased to an at rest position directing pressurized fluid against a first piston flexing its associated diaphragm air compressor compressing air while a second piston simultaneously flexes its associated diaphragm air compressor drawing air therein.

Another object of the subject invention is to provide a fluid powered air compressor having interconnectedpistons moving to simultaneously flex a first diaphragm air compressor compressing air while flexing a second diaphragm air compressor drawing air therein, movement of said pistons controlling application of pressurized fluid to a normally biased slave control valve whereby upon sufficient movement of one of the pistons causes the valve to be moved applying pressurized fluid to a second of said pistons thereby reversing the cycle of opertion.

A further object of the subject invention is to provide a normally biased control valve directing pressurized fluid from an external source to interconnected first and second pistons which, in turn, simultaneously flex respective diaphragm air compressor assemblies compressing air in the first assembly and drawing air into the second assembly movement of the interconnected ticular application to a vehicle leveling system wherein fluid pressurized for use in a power steering system can be utilized to actuate the compressors and provide a reserve of compressed air as required to maintain the vehicle level during various load conditions.

The slave control valve is provided to initially direct the pressurized fluid against a first one of the interconnected pistons moving it to pressurize air in itsassociated diaphragm air compressor. Simultaneously the second piston is moved to withdraw fluid from its associated air compressor thereby actuating it drawing air therein for later pressurization, Sufficient movement of the first piston is effective to direct pressurized fluid against the slave control valve moving it to supply the pressurized fluid to the second piston thereby reversing the cycle. Movement of the second piston in response to the pressurized fluid compresses air in its associated air compressor assembly by flexing its diaphragm while the first piston is simultaneously moved drawing air into its air compressor. Movement of the interconnected pistons is also utilized to eventually exhaust the fluid from the end of the control valve so that it returns to its biased at rest position to begin a new operational cycle.

A general object of the subject invention is to provide a fluid powered air compressor incorporating interconnected pistons flexing respective diaphragm air compressors as they alternately receive pressurized fluid from an external source. A more specific object of the subject invention isto provide a fluid powered air-compressor having a slave pistons a sufficient distance in one direction opening a fluidconduit supplying pressurized fluid against a slave control valve moving it directing pressurized fluid against the second of said interconnected pistons compressing air in the secondassembly and drawing air into the first assembly, further movement of the second piston in a fluid pressurizing direction exhausting the pressurized fluid from the end of the slave control valve allowing it to assume its normal position again directing the pressurized fluid to thefirst piston initiating a new cycle.

The novel features which I believe to be characteristic of my invention are set forthwith particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof will be best understood by reference to be following description taken in conjunction with the accompanying drawing.

Referring now to the drawing:

The fluid powered air compressor of this invention includes a control valve 10 receiving pressurized fluid from an external source such as in one application, pressurized fluid available in a vehicle power steering system. In the particular arrangement of the subject invention, the control valve 10 receives the externally supplied pressurized fluid from a source 11 through a conduit 12, which is connected to a valve cavity 14 in a valve body 16. A spool valve 18, having fluid flow controlling lands 20, 22' and 24, is slidably received within the cavity 14. The valve 18 also includes a stem portion 26 forming astop engaging end 28 of the cavity 14. A reduced diametricalportion 30 is also provided on the valve 18 which acts as a guide for a coil spring 32 engaging end 34 of the cavity 14 and land 20, biasing the valve 18 to a normal drawing.

A conduit 36 connects with the valve body 16 between lands 20 and 22 of valve 18 and is also connected to a first cylindrical chamber 38 containing a first piston 40. The piston 40 is interconnected with a second piston 42 by a rod 44 extending through aperture 46 in a wall 48 separating cylindrical chamber 38 from a like chamber 50 containing the piston 42. The piston 40 position illustrated in the 3 separates chamber 38 into

chambers

52 and 54, the latter having a conduit 56 connected therewith. The conduit 56 is also connected to a diaphragm air compressor housing 58. The air compressor housing 58 is composed of a lower member 60 containing a centrally depressed portion 62 as illustrated. An upper housing member 64 is formed containing a like depressed portion 66, the

portions

62 and 66 engaging a dual diaphragm member 68 and retaining the same therebetween. The dual diaphragm 68 includes a first pumping diaphragm portion 70 defining a fluid chamber 72 and an air compressing chamber 74 on the respective lower and upper sides thereof. The diaphragm 68 also defines a second fluid chamber 76 and a second air compressing chamber 78 on the respective lower and upper sides of a second pumping portion 79 as illustrated. The lower housing member 60, the dual diaphragm 68 and the upper housing member 64 all cooperate to form a first air compressor assembly 80 and a second air compressor assembly 82. The air compressor assembly 80 has a conduit 84 connected in the upper housing portion 64 which contains a check valve 86 regulating the discharge of pressurized air therethrough to a receiver 87 which of course can be vehicle leveling units. The upper housing portion 640! the first aircompressor assembly 80 also has a conduit 88 connected thereto which contains a check valve 90 regulating the flow of inlet air from a source 89 into the air chamber 74 above diaphragm 70. Likewise, the second air compressor as sembly 82 has a conduit 92 connec d to the upper.

housing portion 64 containing a che valve 94 regulating the flow of pressurized flow from air chamber 78 above the pumping portion 79 of the dual diaphragm 68. A second conduit 98 is also connected to the upper housing portion 64 of air compressor assembly 82 and contains a check valve 100 regulating the flow of inlet air into air chamber 78 from source 89.

The bottom portion 60 of the respective air compressor assemblies 80 and 82 each have a pair of

conduits

102 and 104 connected thereto, these conduits respectively containing

relief valves

106 and 108 for a purpose later described. The conduits l02 and 104 connect with a conduit 110 which directs fluid to and from diaphragm reservoir 112.

.With reference again to the second piston 42,

fluid chamber

114 and 116 are provided on opposite sides of the piston in the cylindrical chamber 50. Fluid chamber 114 is connected with fluid chamber 76 in the second air com-pressor 82 by a conduit 118. The fluid chamber'll6, on the closed end of piston 42, is connected with a fluid chamber 120 in valve cavity 14 by a conduit 122, the chamber 120 being defined by

lands

22 and 24 ofthe valve 18. The fluid chamber 52, at one end of the piston 40 is connected with a valve actuating fluid chamber 124 by a conduit 126 when the piston 40 has moved a sufficient distance to the right as viewed in the drawing. Piston 40 contains an annular groove 127 which connects conduits 1 26 and 128 when moved a predetermined distance to the left for a purpose described in the operation of the system. A branch passage 123 containing an orifice 129 connects conduits 122 and 126 adjacent chamber 124 regulating the application of pressure fluid against valve 18.

The conduit 12 conducting inlet fluid from the external source 11 is connected with a branch passage 130 containing a high pressure relief check valve 132, the branch passage 130 being connected with a conduit 134 which in turn connects with conduit 128 providing for return flow to another fluid component or fluid control valve reservoir 136. The relief valve 132 provides for flow to other components in a fluid system should the air compressor system fail and obstruct the usual flow therethrough. A conduit 138 connects the end of the valve cavity 14 containing spring 32 with sump line 128 to maintain a proper pressure differential across valve 18 during transient conditions.

While the components are shown in the drawing as seemingly separated units, it is contemplated'that the preferred embodiment of this invention would incorporate all the components into a single housing.

In operation with a control valve 18 in the position shown, pressure fluid enters conduit 12 and passes through the valve cavity 14 into conduit 36 to fluid chamber 52. The pressurized fluid in chamber 52 moves piston 40 .to the right pressurizing fluid in chamber 54 and directing it through conduit 56 to fluid chamber 72 on the lower side of air compressor diaphragm'70. Movement of the diaphragm upwardly decreases the volume in air chamber 74 compressing air therein which is discharged through check valve 86 and conduit 84 to a receiver 87. In the situation where the subject system is used with an automatic vehicle leveling system the compressed air flow from conduit 84 could be supplied directly to the load leveling units or be supplied to a receiver storing the pressurized air for use in raising the vehicle leveling units as increased loads are applied. When diaphragm has moved upwardly its maximum allowed distance relief valve 106 opens allowing flow of fluid from chamber 72 through

conduits

102 and 110 to diaphragm reservoir 112.

While piston 40 is pressuring fluid in chamber 54 the second piston 42 is forcing fluid from chamber 116 through conduit 122 and valve chamber 120 to the fluid control valve reservoir through conduit 134. Simultaneously movement of the piston 42 to the right increases the volume of chamber 114 withdrawing fluid from chamber 76 on the lower side of diaphragm 79. The movement of diaphragm 79 downwardly increases the volume of airchamber 78 and draws air into the chamber 78 through conduit 88 and check valve i to the air chamber 78. When the diaphragm 79 has moved to its maximum downward position into fluid chamber 76 valve 108 opensand admits fluid from reservoir 112 through conduits and 104, thereby limiting the negative pressure that can be developed in chamber 76.

When piston 40 has moved to the right a sufficient amount, fluid chamber 52 is connected with conduit 126 which supplies pressurized fluid to actuating chamber 124 adjacent land 24 of valve 18. Pressurized fluid also flows through conduit 123 and .orifice 129 regulating the effect of the fluid in chamber 124. The pressurized fluid in chamber 124 moves the valve 18 against the force of biasing spring 32 until land 22 closes conduit 36 and opens conduit 122 to the pressurized fluid entering conduit 12. The pressurized fluid from the external source is then directed to fluid chamber 116 moving piston 42 to the left as viewed in the drawing pressurizing the fluid in chamber 114 for application against diaphragm pumping portion 79 as it flows through conduit 118. Expansion of diaphragm portion 79 compresses air in chamber 78 which is eventually discharged through conduit 92 and check valve 94 and passage 84 to receiver 87. Simultaneously the piston 40 is moved to the left withdrawing fluid from chamber 72 thereby drawing diaphragm 70 downwardly and opening check valve 90 supplying air chamber 74 with air through inlet conduit 88. The pressurized fluid in chamber 116 moves the second piston 42 to the left and upon sufficient movement, the first piston 40 is positioned with its centrally reduced portion 127 adjacent conduit 126 so that the pressurized fluid existing in chamber 124 adjacent land 24 of valve 18 is allowed to flow from the conduit 126 through conduit 128 to the fluid control valve reservoir 136 or other fluid device. The removal of pressurized fluid at the end of the valve 18 allows the spring 32 to bias it to its normal position thereby completing an operational cycle. As long as pressurized fluid is supplied to the conduit 12 the valve 18 will be automatically positioned to complete the aforementioned cycle. The air compressor assemblies 80 and 82 are alternately actuated to supply compressed air through conduit 84 to the receiver 87.

While a preferred embodiment of my invention has been described for purposes of illustration, such description is not intended to limit the scope of this invention except as required by the following appended claims.

I claim:

1. In a fluid powered air compressor receiving pressurized fluid from a source, a cyclically operable control valve, first and second interconnected pistons operating in respective first and second cylindrical chambers, means supplying fluid from said control valve to the first and second pistons respectively, first and second air compressor assemblies each including a diaphragm, said diaphragm dividing each compressor into fluid and air chambers on opposite sides thereof, means connecting said first and secondpistons with the fluid chambers of said first and second air compressor assemblies respectively so as to define complementary connected volumes for the pairs-of pistons and compressors respectively, means connecting said air chambers of said compressor assemblies with a receiver storing compressed air, one-way discharge valves connected in said means controlling flow from each of said compressor assemblies to said receiver, a source of inlet air, means connecting said air source to said air chambers, one-way inlet valves connected between the air chambers of said air compressor assemblies respectively and said air source supplying air thereto as required and means biasing said control valve to a first position wherein the pressurized fluid flows through said control valve from said supply means against said first piston shifting the same pressurizing fluidon the opposite side thereof and discharging into said first air compressor fluid chamber flexing the diaphragm therein, said diaphragm thereby compressing air passing through said discharge valve for storage in said receiver, said second piston moving to withdraw fluid from said second air compressor fluid chamber flexing its diaphragm drawing air from said air source, means selectively connecting the source of pressurized fluid with an end of said control valve and exhausting the fluid therefrom, sufficient piston movement connecting said control valve to the pressurized fluid through said selective connecting means, said control valve moving in response to the pressurized fluid to a position directing the pressurized fluid through said valve against said second piston, said second piston moving to flex the diaphragm in said second compressor assembly pressurizing air in its air chamber which exits through its discharge valve to the receiver while said first piston simultaneously flexes the diaphragm in said first compressor assembly drawing inlet air into its air chamber from said air source, movement of said first piston ultimately reaching a position exhausting the pressurized fluid from the end of said control valve through said means selectively connecting the source of pressurized fluid with the end of said valve thereby allowing the valve to return to its normal position for initiation of a new cycle of operation.

2. In a fluid powered air compressor including a housing receiving pressurized fluid from a source, a cyclically operable control valve, means biasing said valve to a first position, first and second cylinders in said housing, first and second interconnected pistons respectively received in said cylinders, means connecting said control valve independently to one of said first and second cylinders so as to apply pressurized fluid against one of said pistons, first and second air compressor assemblies each including a cavity, a diaphragm in each of said cavities defining a fluid chamber on one side thereof and an air chamber on the other side thereof, means connecting said first and second cylinders on one side of said pistons respectively with the fluid chambers of said first and second air compressor assemblies defining complementary connected volumes for the pairs of pistons 'and compressors respectively, means connecting each of said compressor air chambers with a receiver storing compressed air, oneway discharge valves connected in said means connecting said air chambers with said receiver controlling flow of compressed air from each of said compressors to said receiver, a source of inlet air, means controlling flow of air between said source and said respective air chambers,said first and second pistons moving in their respective cylinders cyclically between air pressurizing strokes reducing said complementary connected volumes and air inlet strokes expanding said volumes, one piston pressurizing air by pumping fluid against and flexing the diaphragm in its respective compressor air chamber discharging the air to said receiver through said discharge valve when said control valve supplies pressurized fluid to said one piston while the other said piston simultaneously draws fluid from its respective compressor fluid chamber flexing the diaphragm drawing air into its respective air chamber, a diaphragm fluid reservoir, conduit means connecting said compressor fluid chambers with said reservoir, fluid pressure limiting valves in said conduit means opening to relieve the pressure in each of said fluid chambers when the respective diaphragms have been actuated to their limit of movement and pressurized fluid continues to be supplied thereto, fluid inlet valves also in said.

conduit means between said diaphragm fluid reservoir and each of said compressor fluid chambers, said fluid inlet valves each opening admitting fluid to its respective fluid chamber when a respective diaphragm has been moved to its maximum limit during the inlet stroke of its associated piston thereby preventing excessive negative pressure on said diaphragms, said control valve first applying pressurized fluid against said first piston moving it on its air pressurizing stroke pumping fluid to the fluid chamber of said first air compressor compressing air discharged to the receiver, said second piston simultaneously moving on its intake stroke withdrawing fluid from said second air compres- 7 sor fluid chamber drawing inlet air into said second air compressor, a control valve fluid reservoir, first means connecting said first cylinder to one end of said control valve and to said control valve fluid reservoir, and second means connecting said second cylinder to said control valve and to said control valve fluid reservoir, sufficient movement of said first piston supplying the pressurized fluid in said first cylinder to one end of said control valve through said first means, said control valve moving directing pressurized fluid to said second cylinder against said second piston moving it on its 8 pressurizing stroke while said second piston moves on its air inlet stroke, sufficient movement of said first piston connecting the pressurized fluid on the one end of said control valve to said control valve fluid reservoir through said first connecting means causing said control valve to move to its first position connecting said second cylinder to said control valve fluid reservoir removing the pressurized fluid from said second piston and again supplying the pressurized fluid to said first cylinder beginning a new cycle.

Claims

1. In a fluid powered air compressor receiving pressurized fluid from a source, a cyclically operable control valve, first and second interconnected pistons operating in respective first and second cylindrical chambers, means supplying fluid from said control valve to the first and second pistons respectively, first and second air compressor assemblies each including a diaphragm, said diaphragm dividing each compressor into fluid and air chambers on opposite sides thereof, means connecting said first and second pistons with the fluid chambers of said first and second air compressor assemblies respectively so as to define complementary connected volumes for the pairs of pistons and compressors respectively, means connecting said air chambers of said compressor assemblies with a receiver storing compressed air, one-way discharge valves connected in said means controlling flow from each of said compressor assemblies to said receiver, a source of inlet air, means connecting said air source to said air chambers, one-way inlet valves connected between the air chambers of said air compressor assemblies respectively and said air source supplying air thereto as required and means biasing said control valve to a first position wherein the pressurized fluid flows through said control valve from said supply means against said first piston shifting the same pressurizing fluid on the opposite side thereof and discharging into said first air compressor fluid chamber flexing the diaphragm therein, said diaphragm thereby compressing air passing through said discharge valve for storage in said receiver, said second piston moving to withdraw fluid from said second air compressor fluid chamber flexing its diaphragm drawing air from said air source, means selectively connecting the source of pressurized fluid with an end of said control valve and exhausting the fluid therefrom, sufficient piston movement connecting said control valve to the pressurized fluid through said selective connecting means, said control valve moving in response to the pressurized fluid to a position directing the pressurized fluid through said valve against said second piston, said second piston moving to flex the diaphragm in said second compressor assembly pressurizing air in its air chamber which exits through its discharge valve to the receiver while said first piston simultaneously flexes the diaphragm in said first compressor assembly drawing inlet air into its air chamber from said air source, movement of said first piston ultimately reaching a position exhausting the pressurized fluid from the end of said control valve through said means selectively connecting the source of pressurized fluid with the end of said valve thereby allowing the valve to return to its normal position for initiation of a new cycle of operation.

2. In a fluid powered air compressor including a housing receiving pressurized fluid from a source, a cyclically operable control valve, means biasing said valve to a first position, first and second cylinders in said housing, first and second interconnected pistons respectively received in said cylinders, means connecting said control valve independently to one of said first and second cylinders so as to apply pressurized fluid against one of said pistons, first and second air compressor assemblies each including a cavity, a diaphragm in each of said cavities defining a fluid chamber on one side thereof and an air chamber on the other side thereof, means connecting said first and second cylinders on one side of said pistons respectively with the fluid chambers of said first and second air compressor assemblies defining complementary connected volumes for the pairs of pistons and compressors respectively, means connecting each of said compressor air chambers with a receiver storing compressed air, one-way discharge valves connected in said means connecting said air chambers with said receiver controlling flow of compressed air from each of said compressors to said receiver, a source of inlet air, means controlling flow of air between said source and said respective air chambers, said first and second pistons moving in their respective cylinders cyclically between air pressurizing strokes reducing said complementary connected volumes and air inlet strokes expanding said volumes, one piston pressurizing air by pumping fluid against and flexing the diaphragm in its respective compressor air chamber discharging the air to said receiver through said discharge valve when said control valve supplies pressurized fluid to said one piston while the other said piston simultaneously draws fluid from its respective compressor fluid chamber flexing the diaphragm drawing air into its respective air chamber, a diaphragm fluid reservoir, conduit means connecting said compressor fluid chambers with said reservoir, fluid pressure limiting valves in said conduit means opening to relieve the pressure in each of said fluid chambers when the respective diaphragms have been actuated to their limit of movement and pressurized fluid continues to be supplied thereto, fluid inlet valves also in said conduit means between said diaphragm fluid reservoir and each of said compressor fluid chambers, said fluid inlet valves each opening admitting fluid to its respective fluid chamber when a respective diaphragm has been moved to its maximum limit during the inlet stroke of its associated piston thereby preventing excessive negative pressure on said diaphragms, said control valve first applying pressurized fluid against said first piston moving it on its air pressurizing stroke pumping fluid to the fluid chamber of said first air compressor compressing air discharged to the receiver, said second piston simultaneously moving on its intake stroke withdrawing fluid from said second air compressor fluid chamber drawing inlet air into said second air compressor, a control valve fluid reservoir, first means connecting said first cylinder to one end of said control valve and to said control valve fluid reservoir, and second means connecting said second cylinder to said control valve and to said control valve fluid reservoir, sufficient movement of said first piston supplying the pressurized fluid in said first cylinder to one end of said control valve through said first means, said control valve moving directing pressurized fluid to said second cylinder against said second piston moving it on its pressurizing stroke while said second piston moves on its air inlet stroke, sufficient movement of said first piston connecting the pressurized fluid on the one end of said control valve to said control valve flUid reservoir through said first connecting means causing said control valve to move to its first position connecting said second cylinder to said control valve fluid reservoir removing the pressurized fluid from said second piston and again supplying the pressurized fluid to said first cylinder beginning a new cycle.