Compressor system

Feb. 7, 1961

J. KASPAR ETAL

2,970,747

COMPRESSOR SYSTEM

Filed Sept. 9, 1958

Sheets-Sheet 1

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Feb. 7, 1961

2,970,747

J. KASPAR ETAL

COMPRESSOR SYSTEM •A ft

<img file="US2970747A_D0002.tif" />

2,970,747

J. KASPAR ETAL

COMPRESSOR SYSTEM

Feb. 7, 1961

Filed Sept. 9, 1958

Sheets-Sheet 3

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Feb. 7, 1961

2,970,747

J. KASPAR ETAL

COMPRESSOR SYSTEM

Filed Sept. 9, 1958

Sheets-Sheet 4

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J. KASPAR ETAL

COMPRESSOR SYSTEM

Feb. 7, 1961

Filed Sept. 9, 1958

2,970,747

Sheets-Sheet 5

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J. KASPAR ETAL

COMPRESSOR SYSTEM

Feb. 7, 1961

Filed Sept. 9, 1958

2,970,747

Sheets-Sheet 6

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United States Patent Office

2,970,747

Patented Feb. 7, 1961

2,970,747

COMPRESSOR SYSTEM

Josef Kaspar, Sepulveda, and Alex J. Bielsks, Woodland Hills, Calif., assignors to International Telephone and Telegraph Corporation, Nalley, NJ., a corporation of Maryland

Filed Sept. 9, 1958, Ser. No. 759,900

Claims. (Cl. 230—162)

This invention refers to a compressor system and more particularly to a diaphragm-type of compressor useful for supplying gas under a desired pressure and free of impurities.

In the operation of a cryostat, for example, it is necessary io supply to the cryostat high pressure gas, usually nitrogen, at room temperature. Tile pressure required is usually in the range of 2,000 to 3,000 p.s.i. and operates in the cryostat on the loule-Thompson effect of expanding gas through a nozzle and regenerative cooling of a heat exchanger that finally produces the temperature of liquified gas used, which in the case of nitrogen is —196° C. This presents problems in that a continuous high pressure gas source must be provided, and the gas must be perfectly free of moisture, oil vapors, and all other impurities. Any impurities present will solidify in the small passages of the cryostat, since the cryostat operates at —196° C., and stop the functioning of the cryostat. A cylinder of gas can be used, provided it meets the purity requirements, until the pressure drops to an unusable value. This puts a time limit on the operation of the cryostat in addition to the fact that the bulk end weight of a large high pressure gas cylinder makes such use practically impossible for airborne equipment.

The present system that is used for recompression and recirculation of the high pressure gas in the cryostat presents grave problems. The equipment necessary to recompress the required amount of gas from one atmosphere to. 200 atmospheres weighs approximately 45 lbs. in the airborne version and uses approximately a two horsepower compressor. In compressing the gas with conventional piston type compressors, the gas becomes contaminated with oil vapors. It is then necessary to remove the oil vapors with oil vapor extractors. In doing so, some of the compressed gas is also extracted. This loss plus other losses of gas through various glands, seals, and fitting of the mechanical equipment used necessitates the use of make up tanks to replace the loss of gas. This means, of course, that eventually all gas available is lost and so limits the operation of the present equipment to about 15 hours. The reliability of the present equipment is questionable and the cost of the numerous and expensive units used therein is high.

It is therefore an object of this invention to provide a device for supplying clean, high pressure nitrogen or other gas for the operation of cryostats or other equipment where clean, high pressure gas is necessary.

Another object of this invention is to provide a small, compact and light weight device to supply clean, high pressure gas applicable for use in aircraft.

A further object is to provide a hermetically sealed compressor wherein the initial charge of gas will last for a substantially long period of time without the necessity of recharging or replacing any of the gas.

A still further object is to provide a compressor for delivery of high pressure gas which does not require motors, reciprocating or centrifugal compressors or pumps.

A feature of this invention is a compressor system which comprises compression means and storage means 5 for substantially continuous delivery of a first fluid at high pressure. A first means introduces the first fluid at low pressure into the compression means to compress the first fluid to high pressure. Means responsive to the first fluid when it reaches a condition of high pressure 10 discharges the high pressure first fluid from the compression means including means to deliver the high pressure first fluid to the storage means. The second means is responsive to the storage of a predetermined amount of high pressure first fluid in the storage means to apply 15 the high pressure second fluid to the storage means to discharge the high pressure first fluid from the storage means. The first fluid may be a gas and the second fluid may be a hydraulic fluid.

Another feature is that both the compression means 20 and the storage means contain chambers and flexible diaphragms which divide each of the chambers into first and second parts at the same time hermetically sealing the first part of each chamber from the second part thereof.

A further feature is that a reservoir is provided wherein the low pressure first fluid returning from a utilization means is stored in the compressor during the compression stroke of the compression chamber and the stored low pressure first fluid is permitted by intake valve means 30 to flow into the compression chamber during the intake stroke.

Still another feature is that valve means are provided in the compressor to alternately deliver high pressure hydraulic fluid to the second part of the compression 35 chamber during the compression stroke thereof to compress the low pressure gas to the high pressure and discharge the high pressure gas from the compression chamr ber, and to the second part of the storage chamber during the pressure stroke thereof to discharge the high pres40 sure gas from the storage chamber.

A further feature is that valve means are provided which are coupled to the diaphragm of the storage chamber and operate to cause the flow of high pressure hydraulic fluid into the storage chamber when the storage 45 chamber has become completely filled with the high pressure gas.

The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the 50 accompanying drawings, in which:

Fig. 1 is a side elevation view of the compressor system of this invention partially in section;

Fig. 2 is a section along line 2—2 of Fig. 1;

Fig. 3 is an elevational view of the opposite side shown 55 in Fig. 1 also partially in section;

Fig. 4 is a flow diagram showing the beginning of the compression stroke in the compression chamber immediately after the end of the pressure stroke in the storage chamber;

Fig. 5 shows a continuation of the compression stroke in the compression chamber and the corresponding portion of the intake stroke in the pressure chamber;

Fig. 6 shows the end of the compression stroke in the compression chamber and the pressure stroke about to 65 begin in the pressure chamber;

Fig. 7 shows a further step in the progress of the pressure stroke in the storage chamber with the intake stroke in the compression chamber completed; and

Fig. 8 is a graph of the various conditions existing in 70 the compressor at different points in the complete cycle.

The compressor system of this invention is basically a complete self-contained unit having a high pressure hy2,970,747 chamber 67 in cap 50. A passage 68 connects the undercut 63 with the end 69 of the valve body 61, thus providing for a connection between oil inlet port 51 and chamber 57 through the valve body 61.

The operation of the compressor system can be best described with reference to flow Figures 4, 5, 6, and 7. ’Hydraulic fluid under pressure from a source 70 enters chamber 47 through the orifice 51 of the housing 48. As shown in Fig. 4, it is channeled by the valve 60 through an orifice 71 in the bushing 48 through passage 46 into part 4 of the compression chamber 2. The high pressure hydraulic fluid causes the diaphragm 6 to flex and move thereby compressing the gas in part 5 of chamber 2. The time required to compress the low pressure gas to the required high pressure is so short that it may be regarded as a substantially instantaneous occurrence. : The compressed gas is forced through the opening 33, the tube 32 and the passage 31α into chamber 31. The high pressure gas then goes through passage 39 into the valve seat chamber 40 opening the valve 42. This admits the high pressure gas into the chamber 41 and the passage 44 where the gas is free to go through the high pressure gas outlet 43 to its required destination, a utilization unit 72. The remainder of the compressed gas goes through tube 45 into part 18 of storage chamber 3 forcing diaphragm 17 to flex and move back to the extreme of chamber 3 filling part 18 with high pressure gas. The slide valve 23 is forced back into valve chamber 24 closing ports 59 and 73. High pressure oil from port 51 going through undercut 63 and through the restricted passage 68 fills chamber 57 with high pressure hydraulic - fluid; this forces the valve 60 to shift to the other extreme of chamber 47. Oil under pressure in part 4 of compression chamber 2 is then released through the passage 46 and the port 71 into the undercut 64 cavity and through the port 55 to return to the reservoir of the hydraulic fluid source 70. This also allows high pressure hydraulic fluid from the port 51 to enter the port 52 and through the passages 53 and 54 to enter part 19 of storage chamber 3. There is thereby exerted a force on the diaphragm 17 causing high pressure gas in part 18 of storage chamber 3 to be forced out into tube 45, passage 44 and chamber 41. The check valve 42 which was forced down by its spring biasing means to close . off chamber 40 when the flow of high pressure gas from ' the compression chamber 2 ceased prevents the high pressure gas from storage chamber 3 from going into chamber 40. The high pressure gas can then go out only through the high pressure gas outlet 43 to the utilization unit 72. ) The expanded gas returning to the compressor enters ’ at inlet 26 in the fitting 25 and enters the valve seat chamber 27. At this point, the low pressure gas goes through the passage 34 and passage 38 into reservoirs 35, 36, and 37. When these reservoirs are filled, the gas opens the 55 valve 28 and flows into the valve chamber 29 and through the passage 30 into the chamber 31. It then flows through the passage 39 into the valve seat chamber 40 but the low pressure returning gas cannot force the valve 42 to open since it is responsive only to the high pressure gas. Chamber 47 is formed θθ The returning low pressure gas must then flow from chamber 31 through the passage 31α into the tube 32 and through the opening 33 into part 5 of compression chamber 2 causing the diaphragm 6 to flex and move to the opposite extreme of chamber 2 thus ejecting the no presber. The return gas then continues to accumulate in part 5 until part 18 of storage chamber 3 is exhausted of high pressure gas. When the high pressure gas in the storage chamber 3 is exhausted, the diaphragm 17 has moved a

draulic intake line and a low pressure hydraulic return line together with a high pressure gas output line and a low pressure gas return line from the utilization source. With reference to Figs. 1, 2, and 3, there is shown a compressor system 1 which includes two spherical chambers, a compression chamber 2 and a storage chamber 3. The spherical compression chamber 2 is divided into two parts 4 and 5 by a flexible diaphragm 6 of substantially hemisperical shape which is capable when flexing of conforming to walls of either half of the spherical chamber 2. : Half of the sphere 2 is formed by a spherical cavity in cap 7 which is designed to accept the thickened ends 8 of the diaphragm 6 to provide a hermetically sealed joint with the main body 9 of the compressor. The other half of the sphere 2 is formed by a hemispherical cavity in the body 9. A threaded clamping ring 10 is screwed into the mating portion of the body 9 to clamp down the spherical cover 7 and the diaphragm 6 against the main body 9 thereby constituting the hermetically sealed compression chamber 2. A washer assembly 11 containing gasketing material such as rubber is provided between the clamping ring 10 and the spherical cover 7 to provide additional sealing. A button 12 is attached to the center of the diaphragm 6 to prevent extrusion of the diaphragm material when the diaphragm is moved to either end of the spherical chamber 2 and will nest in mating cavities 13 or 14. The spherical storage chamber 3 similarly is formed by a hemispherical cavity in cap 15 and a hemispherical cavity in the body 9. The cover 5 is machined to accept the thickened ends 16 of a flexible diaphragm 17 of a substantially hemispherical shape and also capable when flexing of conforming to the walls of either part 18 or 19 of the spherical chamber 3 formed by the flexible diaphragm 17. A threaded clamping ring 29 together with a gasket 21 when screwed into the mating part of the body 9 clamps the diaphragm 17 and the cover 15 securely in place to thereby form the spherical chamber 3. A button 22 is secured to the midpoint of the diaphragm 17 to prevent extrusion of the diaphragm when the diaphragm 17 is at either end of the storage chamber 3. A slide valve 23 is attached to the button 22 and is movable with the to and fro motion of the diaphragm 17 within a chamber 24.

A fitting 25 has an inlet port 26 which connects with chamber 27. Chamber 27 is capped by an intake check valve 28 that controls the fluid flow from chamber 27 to a chamber 29. A passageway 30 connects chamber 29 with a chamber 31 which connects with a passage 31α that is in turn directly coupled to a tube 32. Tube 32 is connected to a chamber 33 which opens on part 5 of the compression chamber 2. A nects chamber 27 with reservoirs means of connecting passage 38. chamber 31 with a chamber 40. ----------- ,. jacent a valve chamber 41 which contains a discharge check valve 42. Chamber 41 is connected to an outlet tube 43 by means of a passage 44. Outlet tube 43 is connected to part 18 of storage chamber 3 by means of a tube 45. A passage 46 couples part 4 of compression chamber 2 with a chamber 47. &lt;“' by a bushing 48 that is sealed within the body 9 on both ends by threaded caps 49 and 50. Chamber 47 is coupled to a source of hydraulic fluid at high pressure by an inlet port 51. Chamber 47 is also coupled to part 19 of storage chamber 3 by means of a port 52 in bushing gg _sure hydraulic fluid from part 4 of the compression cham48, a passage 53, and a passage 54. A port 55 in bushing - ... i_. .

also connects with a passage 56 which provides the return from chamber 47 to the source of hydraulic fluid.

Cap 49 contains a chamber 57 adjacent to chamber 47. ___________ _ ___

A passage 58 connects chamber 57 with ports 59 that 70 against the inner wall of part 18. Since the slide valve open into.chamber 24. A slide valve 60 which comprises ' ' · - · ..a body 61 having a shaft 62 of relatively small diameter and two spool-like undercut portions 63 and 64 with O ring seals 65 is diposed within chamber 47. A tension ------------------- . -.

spring 66 encloses shaft 62 and is disposed within a 75 58 is thereby released and returned to the reservoir of the passageway 34 con35, 36, and 37 by A passage 39 joins Chamber 40 is ad23 is connected to the diaphragm 17, it moves to the extreme of valve chamber 24 opening the port 73 .which is connected to the oil return passage 56. High pressure hydraulic fluid in the chambers 24 and 57 and the passage

2,970 ⁵ fluid pump 70. High pressure hydraulic fluid which is still at this time in part 19 of the storage chamber 3 is prevented from going into the chamber 24 by forcing a check valve 74 which is disposed within the slide valve 23 to close. With the release of pressure in the chamber 57, 5 the spring 66 is strong enough to force the slide valve 60 to the other extreme of the chamber 47. This releases oil under pressure in part 19 through the passages 54 and 53 and the chamber 47 to the outlet passage 56 and thence to the hydraulic reservoir. The cycle is thus completed 10 and the action repeats. When part 18 of the storage chamber 3 is receiving high pressure gas and the slide valve 23 is moving towards the port 59, pressure in chamber 24 is prevented from being produced by forcing open the check valve 74 and allowing oil in the chamber 24 to pass 15 through the check valve chamber 75 and passage 76 into part 19 of the storage chamber 3. When the diaphragms 6 and 17 are at the extremes of their travel and against the walls of the respective chambers 2 and 3 on either side, the soft material of the diaphragms is prevented from 20 extruding through the openings by the buttons 12 and 22.

Fig. 8 shows a time cycle T and the various states that occur in the compression and storage chambers and the reservoirs together with the conditions of the valves that control the flow of the hydraulic fluid and the compressi- 25 hie gas. The sequence of events graphically shown in Fig. 8 during the compression stroke of the compression chamber is as follows:

(1) Valve 66 responsive to pressure of spring 66 moves to the position shown in Figs. 4 and 5. This allows high 30 pressure oil to go to compression chamber 2 and no pressure oil to return to source 76 from the storage chamber 3.

(2) Valve 42 responsive to high pressure gas opens and. the high pressure gas goes to storage chamber 3 and utilization device 72. 35 (3) Valve 28 responsive to high pressure gas closes to prevent high pressure gas from going into return line 26.

(4) Valve 23 moves to close port 73 and close port 59 at end of stroke for pressure buildup in chamber 57.

(5) Valve 74 opens so that no pressure oil from 57 and 40 24 can flow back through 54, 53 and 55 to source 70 and prevents pressure buildup in chamber 24.

(6) Reservoirs 35, 36 and 37 receive low pressure gas from return line.

(7) High pressure oil goes through restricted passage 68 until at the end of the compression stroke that is the ⁴⁵only path left so pressure in 57 builds up very rapidly until spring 66 is forced back.

The sequence of events during the pressure stroke of the storage chamber is as follows:

(1) Valve 60 moves to the position shown in Figs. 6 and 7. This allows high pressure oil to go to the storage chamber 3 and no pressure oil to return from compression chamber 2 to the source 70.

(2) Valve 42 closes to prevent the high pressure gas from the storage chamber 3 from going into the compres- ⁵⁵sion chamber 2.

(3) Valve 28 is forced to open and lower pressure gas from the return line 26 and the stored low pressure gas in reservoirs 35, 36 and 37 flow into the compression chamber 2. ⁶⁰ (4) Valve 23 moves to open port 59 to bring high pressure oil into chamber 24 then opens port 73 to allow high pressure oil to return to the source at the end of the pressure stroke. As the pressure drops in 57, spring 66 forces valve 60 to return allowing the high pressure oil to go to the compression chamber 2 and the no pressure oil to return to the source 70 from the storage chamber 3. Valve 74 is closed preventing high pressure oil from going into chamber 24. -, θ

The reservoirs are included in the compressor body 9 to provide a storage means for low pressure gas during the compression stage in the compression chamber 2. The volume of the reservoirs is made relatively small so that the pressure will not go down too far below the intake 75 ,747,

6pressure of the compression chamber, which would be the case if the reservoirs were made too large. If there were no reservoirs for the storage of low pressure gas during the compression stroke, then there would be a back pressure that would interfere with the operation of the utilization device.

Hydraulic fluid at high pressure is the only power required to operate this compressor. In the embodiment of this invention hydraulic fluid at 3,000 p.s.i. is used for the power therein, low pressure nitrogen at 150 p.s.i. is supplied to the compression chamber and the high pressure gas output is at 3,000 p.s.i. The 3,000 p.s.i. hydraulic fluid is available on all aircraft and is normally used for operating landing gear, flaps, etc., and is required mainly in landing and take-off operation. More than adequate surplus hydraulic power is available once the aircraft is airborne. In installations other than aircraft, hydraulic power can be supplied from any other source. The requirement for this embodiment is approximately 600 cc. of 3,000 p.s.i. hydraulic fluid per minute. In the gas system of this compressor the gas is never exposed to lubricated mechanical parts or to surfaces which have been occupied by any other medium than the gas used. This prevents contamination of the gas and maintains the original purity of the introduced gas. Furthermore, since the original charge of gas is relatively a small volume, a reasonable amount of impurities can be tolerated because if the amount of impurities present in the original charge are not sufficient to clog the cryostat, or a similar utilization source, in the first cycle, no further trouble should be experienced since the contamination effects are not additive. This is not the case in other systems where new quantities of contaminants are always introduced in the cryostat and no matter how small the quantity it is trapped in the cryostat and the additive effect will eventually clog the small passages thereof. All of the gas chambers and the entire gas system are hermetically sealed. Therefore, the original charge of gas should last indefinitely subject, of course, to the defusion of gas through the metal walls and the diaphragms.

It is to be understood that although in the examples quoted the hydraulic fluid pressure is at 3,000 p.s.i., low pressure gas is at 150 p.s.i., and high pressure gas is at 3,000 p.s.i., these figures are by way of examples only and this compressor is equally well adapted to operate at other pressures than those specified.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.