US2141057A

US2141057A - Gas compressor

Info

Publication number: US2141057A
Application number: US163633A
Authority: US
Inventors: Aubrey C Whiles
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-09-13
Filing date: 1937-09-13
Publication date: 1938-12-20
Anticipated expiration: 1955-12-20

Description

A. C. WHILES GAS COMPRESSOR Dec. 20, 1938.

Filed Sept. 13, 1937 5 Sheets-Sheet 2 3 Sheets-Sheet 3 A. c. WHILES GAS COMPRESSOR Filed Sept. 13, 1937 Dec. 20, 1938.

INVENTOR.

Patented Dec. 20, 1938 UNITED STATES PATENT OFFICE GAS COMPRESSOR Application September 13, 1937, Serial No. 163,633

10 Claims.

My invention relates to a gas compressor; and the objects of my invention are:

First, to provide a gas compressor which is compact relative to its capacity to deliver compressed gas;

Second, to provide a gas compressor which delivers the compressed gas at a relatively high pressure;

Third, to provide a gas compressor which delivers a relatively steady flow of compressed gas;

Fourth, to provide a multistage gas compressor having a gas receiver intermediate its stages of compression; and

Fifth, to provide a gas compressor which is simple of construction and operation with respect to its purpose, durable, efficient, and which will not readily deteriorate or get out of order.

With these and other objects in view as will appear hereinafter, my invention consists of certain novel features of construction, combination, and arrangement of parts and portions as will be hereinafter described in detail and particularly set forth in the appended claims, reference being had to the accompanying drawings and to the characters of reference thereon which form a part of this application in which:

Figure 1 is a sectional view along the line ll of Fig. 2 showing parts and portions in elevation to facilitate the illustration; Fig. 2 is a plan view taken along the line 2-2 of Fig. 1 to show the cylinder arrangement and is of the same scale as Figs. 1 and 4; Fig. 3 is an enlarged scale sectional view along line 3-3 of Fig. 2 through the cylinder head id on the high pressure cylinder 4 showing particularly the valve arrangement therein and. showing cylinder 4 fragmentarily; Fig. 4 is a sectional view taken along line 4-4 of Fig. 1 and is of the same scale as Fig. 1 and shows particularly the crankshaft and connecting rods; Fig. 5 is a sectional view of the intermediate gas receiver only on an enlarged scale along the line 5-5 of Fig. 1; Fig. 6 is a fragmentary sectional view along the line 6-4 of Fig. 5 and on the same scale as Fig. 5 showing parts and portions in elevation to facilitate the illustration, and showing particularly the valve arrangement. in said gas receiver; Fig. 7 is a sectional view taken along line l-'! of Fig. 6 of the same scale as Figures 5 and 6, to show the low pressure cylinder inlet valve guide and valve port, and how said guide is secured within said port; Fig. 8 isa sectional view along line 8-8 of Fig. '7 further disclosing how said valve guide is secured within said valve port; Fig. 9 is a partial sectional view along line 9-9 of Fig. 10 of the gas compressor in its modified form, is of the same scale as Fig. 1, and shows particularly how the pistons for the ,high compression cylinders are geared to the piston for the low pressure cylinder; Fig. 10 is a top or plan view of the modified form of the gas compressor ,5 along line Iii-l0 of Fig. 9 to show the cylinder arrangement and is of the same scale as Fig. 9; and Fig. 11 is a fragmentary sectional view taken through the line I !-l I of Fig. 9 showing particularly how the crankshaft for each high pressure 10 cylinder is supported and how the gear which meshes with the gear for the piston of the low pressure cylinder is secured thereon.

The subject matter ofthis application is disclosed in part in my application, Serial No. 54,682, 15 filed Dec. 16, 1935.

Similar characters of reference refer to similar parts and portions throughout the several views of the drawings:

The crankshaft casing-and cylinder support '20 member 1, the crankshaft casing cover plate 2, low pressure cylinder'3, high pressure cylinders 4,

5, t, and 1, intermediate gas receiver 8, crankshaft 9, low pressure cylinder inlet valve l0, and intermediate gas receiver inlet valves H, [2,13, and I4 constitute the principal parts and portions of my gas compressor.

The crankshaft casing and cylinder support member I is substantially box shaped in its outward dimensions as will be seen from Figures 2 and 4, excepting that in its cross section, as seen best in Fig. 1, it is six sided with its bottom side being formed by the removable crankshaft casing bottom cover plate 2, said cover plate being secured to the member I by means of bolts la, and its two removable longitudinal side plates lg, the two ends and the top sides lb', lo, and Id being in one integral member. Rigidly secured at its lower end to the upper side, lb, of crankcase member 1 and extending upwardly therefrom, the 40 low pressure cylinder 3 stands vertically, and is centrally positioned with respect to said member 1, all as seen best in Figures 1, 2, and 4. Positioned about and equidistant from cylinder 3 are four

high pressure cylinders

4, 5, 6, and I. Said high pressure cylinders are not vertically disposed with respect to base member I, as is cylinder 3, but stand at an acute angle to the vertical. Cylinder 4 is correlated to 5 as is 6 to I as will be hereinafter described. For the particular structure shown the angle between the axes of

cylinders

4 and 5 and the axes of cylinders 6 and 'l is exactly 72. The axis of each of

cylinders

4, 5', 6, and '1 makes an angle of exactly 36 with the vertical.

Cylinders

4 and 6 are rigidly secured at their lower ends to the side lc of member I, and cylinders 5 and T are similarly secured to side Id of member I, it being noted that side I is perpendicular to the axes of

cylinders

4 and 6, and that side Id is perpendicular to the axes of cylinders and 1. Hence, it will be seen that a V is formed by the axes of

cylinders

4 and 5, and of cylinders 6 and 'l. V

Reciprocally mounted within low pressure cylinder 3 is a piston 3a of any conventional type. Operatively connected to piston 3a by means of a wrist pin is the connecting rod 317. Similarly positioned within

high pressure cylinders

4, 5, 6, and I are suitable pistons of any conventional type, said pistons being operatively connected to connecting rods by means of wrist pins. In Fig.

' 1, and to some extent in Fig. 4, the particular arrangement of connecting rods is shown for the correlated cylinders, and particularly in Fig. 1 the correlation between cylinders i and 5 is disclosed. The correlation between cylinders S and i is the same as that between cylinders e and 5. Because of the V arrangement of the cylinders, one of the connecting rods for each of the correlated pairs of cylinders is articulately connected with the other. Hence, as shown in Fig. 1 the connecting rod 412 for piston 4a is articulately connected with connecting rod 51) of piston 5a b means of a wrist pin 50.

Lying directly beneath and in the axis of cylinder 3 is the crankshaft 9. Also, said crankshaft is so journaled within the member I that it passes through the apex of each V formed by the axes of

cylinders

4 and 5, and cylinders 6 and I. The crankshaft 9 is journaled in the above described position within member I by means of bearing members !e and rotatably se cured thereto bymeans of removable bearing cap ,members If, all as seen best in Figures 4 and 1.

To the middle or" crankshaft 9 and at the crank portion 9a is journaled the lower end of connecting rod 3?) of low pressure piston Ed by means of removable connecting rod bearing cap 30. On one side of the middle is journaled to crank portion 912 the connecting rod Ebof the piston for cylinder 5. At an equal distance on the other side of the middle of crankshaft 9 is journaled to the crank portion 90 the connecting rod lb of the piston for cylinder 1, all as seen best in Figures l and 4. Since the piston for cylinder 4 is articulately connected with the connecting rod for piston of cylinder 5, and since the piston of cylinder 6 is articulately connected with the connecting rod for piston of cylinder 1, and since the piston 3a of cylinder 3 is connected with coni necting rod 311, then as the crankshaft rotates all of said pistons reciprocate, as they are all connected either directly or articulately to crankshaft 9. Although the travel for piston 3a, has been shown as equal to thatfor each of the high pressure cylinders, such an arrangement may be deviated from; that is, the travel for the high pressure pistons may be less than that for the low pressure piston simply by making the throw. of the crank portions for each of said pairs of correlated pistons less than the throw of the'crank portion for the low pressure piston.

Positioned coaxially on top of low pressure cylinder 3 is a hollow cylindrical shaped member 8,

'hereinbefore called the intermediate gas receiver.

member 8b. Positioned within the walls of member 8, and standing between partition 8a and cover 8b, are four partitions 80, said partitions 80 extending radially away from the center of member 8. Extending through the center of member 8 from the under side of its cover 31) to partition 8a is a tubular portion 8d. It will be noted that portion 801 is integral with 8d of member 8. Connecting with this tubular portion 8d are the ends of the four radial partitions 80. It will also be noted that the ends of the partitions 8c opposite the portion 8d are integral with the outside cylindrical wall of member 8. Hence it will be seen from Fig. 5 that the space within the intermediate gas receiver 8 is divided into four separate compartments by the cylindrical wall of member 8, by the cover 81), by the bottom partition 8a, by the radial partitions 8c, and by the tubular portion 8d. It will be further noted from Figures 5' and 6 that the member 3 is rigidly secured to the compression end of the low pressure cylinder 3 by means of stud bolts 3d, the lower end of each of said stud bolts being screw threaded within the wall of cylinder 3, andthat the cover 8b is rigidly secured to member 8 by the same bolts 3d. In this manner the partition 8a of the intermediate gas receiver 8 serves as a cylinder head for the low pressure cylinder 3. From Fig. 6 it' can be seen that the bore within the tubular portion 801 communicates with the cylinder'3, and further, that there is a corresponding hole of slightly re- *duced diameter in the cover 822 that, fits over said cover 3?), is a valve guide 8e, said guide being rigidly secured to the cover member 81) by means of lug portions 8 on the top side and by lug portions 89' on the bottom side, all as shown best in Figures 6 and 8. It will be noted that said lugs 8 and 89 do not close the port, sufficient space being allowed for gas to pass by, as seen best in Fig. G. Positioned within valve guide 86 is the stem of inlet valve H], the valve head seating against the under surface of partition 80: and extending into the cylinder 3 from the end of the port 8d. To keep said valve closed a spring la is held between a cotter pin lb and the upper lugs 8]. In this manner a poppet inlet valve is provided for the low pressure cylinder 3.

Extending downwardly from the under side of cover 8b and equidistant from the center of said cover are four studs. Only studs Ha and [4a show in the drawings, but there is one in each of the four compartments into which the intermediate gas receiver 8 is divided. Each of said studs is rigidly secured .by its upper end to cover 8?). Over the lower ends of each stud are rigidly secured sleeves II b, 12b; l3b, and Mb. Each sleeve has an internal bore substantially the diameter of the stud to which it is secured. Within the lower end of the bore of each of the sleeves llb, 12b, I31), and Mb is reciprocally mounted the upper end of valve stems of valves 1 1, l2, l3, and I4. Within each of said bores and between the lower end of each of said studs and the upper end of each of said valve stems is a spring. In Fig. 6 this arrangement is shown in detail for valves II and I4. .Valves l2 and I3 though not shown are identical in arrangement. The said springs shown as He and ldcserve to push said valves II. and M respectively against their respective seats. These valves II, III, I3, and I4 seat in their respective ports in'the partition member 8a. In Fig. 6 ports Nd and I4d for valves II and I4 respectively are shown. Valves I2 and I3 are identical in this arrangement. Fig. 5 shows that there is one of said valves in one each of the four compartments into which the intermediate gas receiver 8 is divided; and it is obvious from Fig. 6 that the valves II and I4 through their respective ports Nd and I4d communicate directly with the low pressure cylinder 3.- Though not shown, so also do the valves I2 and I3. It will be seen that these valves are arranged to admit gas from the low pressure cylinder 3 and to prevent its escaping back into cylinder 3.

' To the

high pressure cylinders

4, 5, I5, and I are secured the cylinder heads 4d, 5d, 6d, and Id respectively. Each of said cylinder heads is provided with conventional poppet inlet and exhaust valves. In Fig. 3 the cylinder head for cylinder 4 is shown sectionally as taken along line 33 of Fig. .2. In the port 46 is positioned an inlet poppet valve '4), the head of said valve seating against the inner side of cylinder head 4d. A valve spring 4g'is provided to hold valve '4f closed .normally. Positioned within the exhaust port 4h is a poppet valve 41', the head of said valve seating against a reduced portion of port 4h. Positioned within said port 4h is a spring 49'. An externally threaded plug 47c screws into said port and holds said spring between it and the head of the valve 42 so as to normally hold said valve closed. This plug 4k serves also as a valve guide for valve 41.

Connecting to the inlet port 4c, in any conventional manner, is a tubular conductor 42. Similarly connecting with each of the other cylinder heads 5d, 6d, and Id are tubular conductors 5a, 62, and I2 respectively. Each of said conduits communicates with a different one of the four compartments hereinbefore described into which the intermediate gas receiver 8 is partitioned.

Referring to Fig. 1 the low pressure piston 3a will be seen at the bottom of its intake stroke and just about to begin its compression stroke. The crankshaft 9, as indicated in Fig. 1, rotates clockwise. The crank portion 9b for high pressure pistons 4a and 5a is 108 behind the crank portion 9a for the low pressure piston 3a. The crank portion 90 for high pressure pistons 6a and la leads crank portion Set by 108. Since the correlated cylinders 4'and 5 are 72 apart in a V arrangement as hereinbefore described, their pistons 4a and 50 will not reach the bottom of their respective strokes simultaneously, but 411 will precede 5d by 72. Similarly for correlated cylinders 6 and I, 6a will precede Ia by 72. By the arrangement shown each piston'makes one complete compression stroke and one complete intake stroke for each revolution of crankshaft 9, first the low pressure piston 3a, followed by 4a 72 later, which in turn is followed by 5a 72 later, which in turn is followed by 6a, 72 later, which in turn is followed by To 72 later.

The cycle of operation of my gas compressor is as follows: Crankshaft 9 is rotated by any suitable means. Gas is admitted to the low pressure piston 3a on its downward stroke through intake poppet valve I0. On starting the compression stroke of piston 3a, the poppet valve IIJ, because of the pressure differential and because of spring against the pressure of their respective springs to admitthe gas. The total volume of the four compartments is substantially less than the volume of cylinder 3. The poppet valves II, I2, I3, and I4 are closed by their respective springs when piston 3a reaches the end of its compression stroke. By means of

tubular conductors

42, 52, 62, and 12, each one of the four compartments within intermediate gas receiver 8 communicates with one of the

high pressure cylinders

4, 5, 6, and I.

The gas compressed into each of the said four compartments is retained there, being prevented from escaping back into cylinder 3 by valves II, I2, I3, and I4, and not being admitted to the

high pressure cylinders

4, 5, 6, and I for further compression until the respective pistons of said

cylinders

4, 5, 6, and I have reached the top of their respective strokes. On reaching this point in the cycle of compression, a poppet valve for each of said high pressure cylinders opens due to a pressure differential of gases and against its valve spring to admit gas from gas receiver 8. On reaching the end of the intake stroke and the beginning of the compression stroke, said inlet valve closes by spring action and gas pressure. On reaching a certain predetermined pressure in the compression of the gas in each of the high pressure cylinders an exhaust poppet valve opens, the pressure of the compressed gas acting against the valve spring to open said valve, and the gas is released through said exhaust valve toa gas receiver in any conventional manner (not shown) wherein said gas may be retained for use. I I

It will be noted that one low pressure cylinder feeds four high pressure cylinders, each of said high pressure cylinders being of substantially smaller diameter than said low pressure cylinder, their ratios of diameters depending upon the degree of compression desired, and that thehigh pressure cylinders do not reach compression together, but 72 apart in consecutive order, the low pressure cylinder preceding the first of the high pressure cylinders to reach compression by 72, so that in one revolution of the crankshaft all five cylinders will have reached compression. It will be further noted that all five pistons are driven from one crankshaft.

The foregoing description is of the preferred form of the gas compressor. In Figures 9, 10, and 11 is disclosed a modified form. In this modified form the low pressure cylinder 3, the

high pressure cylinders

4, 5, 6, and I, and the intermediate gas receiverB, as hereinbefore described, are used. Also the cylinder heads 4d, 5d, 6d, and Id are used in connection with their respective

high pressure cylinders

4, 5, 6, and I.

The principal difference between the preferred form and the modified form of gas compressor is that in the preferred gas compressor all pistons for both high and low pressure cylinders 'are driven from one crankshaft and that to accomplish this end the high pressure cylinders are positioned in the hereinbefore described V arrangement, while in the modified form each piston for the various high and low pressure cylinders is driven from a separate and individual crankshaft and that each crankshaft in connection with its respective high pressure cylinders is driven through appropriate gears from the crankshaft for the low pressure cylinderpiston and that consequently all cylinders can stand vertically and are grouped about the central low pressure cylinder. In both the preferred form and in the modified form this grouping allows a compact arrangement.

The crankshaft casing and cylinder support member I5 is box shaped as will be seen from Figs. 9 and 10; All the

cylinders

3, 4, 5, 6, and 'l are secured at their lower ends in the normally horizontal cover plate I5a and stand vertically with respect thereto. Secured between the cover plate I5a and the bottom plate I522 are the side plates I50 and I5d. The cover plate Ilia is secured to bottom plate I51) by bolts I56.

Lying directly beneath the cylinder 3 and intersecting its axis is a crankshaft I6. 'Ihis crankshaft is journalled'within casing and cylinder support member I5 and extends through said member I5 as shown by dotted outline in Fig. 10, the end ISa extending outside the end of casing I5 connecting with an external source of rotary power. The piston 3a within low pressure cylinder 3 is connected with crankshaft It at crank portion I$a by means of connecting rod 3b so as to reciprocate within cylinder 3 with the rotation of said crankshaft I6. 7

To one end of crankshaft I6 is keyed gear IBb, and to the other gear Ific, as shown in Figs. 9 and 10. Of the same diametral pitch as gear I61) and meshing therewith are gears I1 and I8. Of the same diametral pitch as gear Ito and meshing therewith are gears I9 and 20. All the afore:

said gears I62), I50, IT, is, I9, and 2%) are of the same diametral pitch. Gears IT, IS, I9, and 26 are keyed to crankshafts 2!, 22, 23, and 24 respectively.

Figure 11 is a sectional view along the line II-II of 'Fig. 9 and shows in particular how crankshaft 22 is supported within member I5 hereinbefore described. One end of this crankshaft 22 isjournalled within a bore 159 within a boss Ifih in a removable end plate E5). The

outer end of said crankshaft 22 is threaded to,

receive a castle nut 22a and a washer 22b. The nut 22a is pinned to the end of shaft 22 by a cotter pin 220. Gear I8 is keyed to crankshaft 22 by key I8a. The inner end of shaft 22 is journalled within a bearing post I52 which post I52 is cast integral with bottom plate I51). A removable bearing cap I5? is provided. Journalled between the crank cheeks22d of crankshaft 22 is the lower end of connecting rod 5?) for piston 5a. Hence as crankshaft it rotates crankshaft 22 will also rotate, since the two are geared together by gears Ifib and I8. And because gears I61) and I8 have the same diametral pitch the crankshafts I5 and 22 will revolve at the same rate of rotation;

The other crankshafts 2!, 23, and 24 are supported within member I5 in exactly the same manner as is shaft 22, and the shafts 2|, 23, and 24 will turn at the same rate of rotation as will shaft I6 because of gears Il, I9, and 20 as hereinbeforedescribed. I

The piston 4a is connected with crankshaft 2i by connecting rod db; the piston for. cylinder 6 is similarly connected with crankshaft 23 and the piston for cylinder I similarly connected with crankshaft 24. The throw for each of crankshafts 2|, 22, 23, and 24 is exactly the same as the throw for crankshaft I5. Hence the pistons for

cylinders

3, 4, 5, t, and I have exactly the same stroke, the same as in the preferred form of gas compressor.

The order of compression is the same in the modified form as in the preferred form.

The mode of operation is the same as in, the

preferred form except that in the modified form each of the high pressure cylinders is driven from its respective crankshaft and said crankshafts are geared together to operate as a unit, all as hereinbefore described.

Though I have shown and described a particular construction, combination, and arrangement of'parts and portions. I do not wish to be limited to this particular construction, combination, and arrangement, but desire to include in the scope of my invention the construction, combination, and arrangement substantially as set forth in the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a multistage gas compressor, a low pressure cylinder, a piston reciprocally mounted therein, a plurality of high pressure cylinders, pistons reciprocally mounted in each of said high pressure cylinders, a crankshaft operably connected to all of said pistons, a gas receiver intermediate the low pressure cylinder and the high pressure cylinders and operably communicating with said low pressure cylinder, and partitions, in said gas receiver dividing said receiver into a plurality of compartments depending upon the number of high pressure cylinders,'one each of said compartments operably communicating with one each of said high pressure cylinders.

2. In a multistage gas compressor, a low pressure cylinder, a piston reciprocally mounted therein, a plurality of high pressure cylinders, pistons reciprocally mounted in each of said high pressure cylinders, a crankshaft operably connected to all of said pistons, a gas receiver intermediate the low pressure cylinder and the high pressure cylinders, partitions in said gas receiver dividing said receiver into a plurality of compart- 'ments depending upon the number of high pressure cylinders, one each of said compartments operably communicating with one each of said high pressure cylinders, and an inlet valve in each of said compartments, each said inlet valve communicating, with the low pressure cylinder.

3. In a multistage gas compressor, a low pressure cylinder, a'pistcn reciprocally mountedtherein, a plurality of high pressure cylinders, pistons reciprocallymounted in each of said'high pressure cylinders, a crankshaft operably connected to all of said pistons, a gas receiver intermediate the low pressure cylinder and the high pressure cylinders, partitions in said gas receiver dividing said receiver into a plurality of compartments depending upon the number'of high pressure cylinders, one each of said ccinpartments operably communicating with one each of said high pressure cylinders an inlet valve in each of said compartments, each said inlet valve communicating with the low pressure cylinder, and an inlet valve for said low pressure cylinder positioned within said gas receiver, the port thereof extending therethrough and communicating with said low pressure cylinder,

4. In a multistage gas compressor, a low pressure cylinder, a piston reciprocally mounted therein, a plurality of high pressure cylinders, pistons reciprocally mounted in each of said high pressure cylinders, a crankshaft operably connected to all of said pistons, a gas receiver intermediate the low pressure cylinder and the high pressure cylinders, said receiver being secured to said in said gas receiver dividing said receiver into a plurality of compartments depending upon the number'of high pressure cylinders, one each of said compartments operably communicating with one each of said high pressure cylinders, an inlet valve in each of said compartments; each said inlet valve communicating with the low pressure cylinder, and an inlet valve for said low pressure cylinder positioned within said gas receiver with the portof said valve extending therethrough to the said low pressure cylinder.

5. In a gas compressor, the combination of a low pressure compression member, a plurality of high pressure compression members, an intermediate gas holder operably communicating with said low pressure compression member, and partitions within said gas holder dividing said holder into a plurality of compartments, one for each of said high pressure compression members and operably communicating therewith.

6. In a gas compressor, the combination of a low pressure compression member, a plurality of high pressure compression members, an intermediate gas holder, partitions within said gas holder dividing said holder into a plurality of compartments, one for each of said high pressure compression members and operably communicating therewith, and an inlet valve in each of said compartments and each of said inlet valves communicating with said low pressure compression member.

7. In a gas compressor, the combination of a low pressure compression member, a plurality of high pressure compression members, an intermediate gas holder, partitions within said gas holder dividing said holder into a plurality of compartments, one for each of said high pressure compression members and operably communicating therewith, an inlet valve in each of said compartments and each of said inlet valves communicating with said low pressure compression member, and an inlet valve for said low pressure compression member positioned within said gas holder, the port of said valve extending through said holder and communicating with the low pressure compression member.

8. In a gas compressor, the combination of a low pressure cylinder, a plurality of high pressure cylinders, an intermediate gas holder communicating with said low pressure cylinder, said gas holder being secured to the compression end of said low pressure cylinder and serving as a cylinder head therefor, and partitions Within said gas holder dividing said holder into a plurality of compartments, one for each of said high pressure cylinders and operably communicating therewith.

9. In a gas compressor, the combination of a low pressure cylinder, a plurality of high pressure cylinders, an intermediate gas holder, said gas holder being secured to the compression end of said low pressure cylinder and serving as a cylinder head therefor, partitions within said gas holder dividing said holder into a plurality of compartments, one for each of said high pressure cylinders and operably communicating therewith,

and an inlet valve in each of said compartmentsand each of said inlet valves communicating with said low pressure cylinder,

10. In a gas compressor, the combination of a low pressure cylinder, a plurality of high pressure cylinders, an intermediate gas holder, said gas holder being secured tothe compression end of. said low pressure cylinder and serving as a cylinder head therefor, partitions within said gas holder dividing said holder into a plurality of compartments, one for each of said high pressure cylinders and operably communicating therewith, an inlet valve in each of said compartments and each of said inlet valves communicating with said low pressure cylinder, and an inlet valve for said low pressure cylinder positioned within said gas holder, the port of said valve extending through said holder to said low pressure cylinder.

AUBREY C. WHILES.