US2799444A - Hydraulically operated compressors and the like - Google Patents

Description

' HYDRAULIQALLY OPERATED COMPBESSORS'; AND THE LIKE Filed March 13, 1956 .Ifily 16, 1957 o. J. SCHEMMEL 2 Sheets-Sheet l Inveni'or 0110 II Sche incl, 7 xfika.

July 16, 1957 o. J. SCHEMMEL HYDRAULICALLY OPERATED COMPRESSORS, AND THE LIKE Filed March 15; 1956 2 Sheets-Sheet 2 10615- I ha m Invenror:

OHoJISohe me hm.

HYDRAULICALLY OPERATED coMPREssoas AND THE LIKE Otto .I. Schernmel, Chicago, Ill.-

Application March 13, 1956, Serial No. 571,290

8 Claims. (Cl. 23G-.-53)

This invention relates to improvements in hydraulically operated compressors, and the like. The compressors herein disclosed are intended especially for the compression of vapors which are used in refrigerating operations, wherein the vapors are compressed sufiiciently to condense them to the liquid phase at normal operating temperatures, preliminary to the later boiling and expansion of the so-liquified vapors in suitable expansion elements to produce the desired refrigerating action. The structures herein disclosed are designed to produce such desired compressing action by use of oil or other suitable and available power liquid under pressure as a motive power, it being noted that various refrigerating operations are desired at locations where such liquid is available under pressure at times and in amounts needed to perform the desired refrigerating operation, while other sources of power are. not conveniently available. One such important application of the compressors herein disclosed is in connection with the refrigerating of trucks for the carriage of perishable commodities such as fresh fruits, vegetables, etc. Many other useful applications of the features of construction herein disclosed will suggest themselves to the student of this specification. copending applications for Letters Patent of the United States, Serial No. 405,599, filed January 22; 1954, now Patent No. 2,791,370, for Improvements in Hydraulically Operated Compressor, and Serial No. 526,921, filed August 8, 1955 for Improvements in Fluid Operated Compressors, and the Like, I have also disclosed devices and structures intended for the same or similar uses as those erein disclosed.

A prime object of the present invention is to provide a very simple structure capable of performing the desired compressing operations by use of available liquid under pressure, and a structure in which the necessary valving operations are produced by a minimum number of parts of simple design. In this connection I have herein disclosed arrangements in which only a single valve is required for the delivery of the pressure liquid to the two compressing elements in alternation, and with release of liquid from each actuating cylinder in proper fashion and timing to allow its power plunger to promptly return to its home or return position by a full stroke movement. The actuation of such valve element is performed hydraulically with a reciprocating movement between two control positions corresponding to the two actuating cylinders. An important feature in this connection resides in the provision of arrangements such that hydraulic lock of such valve element cannot occur prior to full valve movement in either direction of control. Thereby there is assurance of full and complete port openings and closings for all operations within all intended speeds of reciprocation or cycles of compression;

' In connection with the foregoing it is a further object of the invention to provide arrangements such that the necessary passages or conduits for transfer of the power liquid may be made short and direct, to thereby reduce In mynited States Patent O "ice the tendency to production of hammer effects due to fast valve closing movements. At the same time such shortening of these passages will reduce the pressure loss dueto flow of the pressure liquid through such passages.

A further object of the invention is to provide structures in which .the main valve operations are produced hydraulically, the admission of pressure liquid to and release of liquid from the opposing faces of such. valve being, directly controlled by valving elements comprising portions of the power plungers controlled by such main valve movements. By this means it is not necessary to provide special valving elements to control the shifting of the main valve, back and forth, since such controls are produced in proper alternation by the movements of the power plungers controlled by such main valve. There, also, there is assurance that full stroke operations of the power plungers will be produced since the shifting of the main valve does not occur until the plunger element. has reached its terminus of movement;

I have herein disclosed two. embodiments of the features of my present invention. In one of these the two power plungers are located in alignment and are directly connected together, both plungers reciprocating in, unison due to their physical connection together. In this arrangement the main valve is conveniently located adjacent to and parallel to the pair of power plungers with very short hydraulic connections between the main valve and; the power cylinder ports. Furthermore, with this arrangement the return of each power plunger to its home position is produced by direct physical connection to, the other powerplunger. In the alternate arrangement herein disclosed both of the power plungers are located parallel to and close. to each other, and the main valve is located close to the ends of the two. power cylinders and at right angles to the axes of said cylinders.' In this arrangement the homing movement of each power plunger is performed by a suitable spring. In this alternate arrangement the mainvalve is shifted hydraulically between its two extremes of movement and, under control of valving operations directly produced by the two power plungers themselves. Thus, both. embodiments herein disclosed are similar in their respective main valve operations, under direct control of the two power plungers.

Each power plunger is directly connected to a vapor compressing element. In the embodiments herein disclosed these vapor compressing elements comprise piston elements directly connected to the respective power plungers and reciprocating with said plungers. However, I do not intend to limit myself to such piston arrangeent, except as I may do so in the claims, as evidently other movable wall compressor space devices may be substituted for the pistons, such other forms of movable wall construction having their movable wall elements moved in the compressing direction by the power plungers. As an example of' such a modified arrangement I may mention the use of diaphragm type compressor elements, as well as others,

It; is noted that when using the alternate arrangement previously referred to, itmay sometimes be desirable to adjust the spring force developed for the returning movement of each power plunger, this being especially true when operating at rather high rates of reciprocation. I have provided means whereby the compression of the spring for each power plunger may be readily adjusted from time to time after the unit has been assembled, to thereby adjust the amount of preloading of such spring as needed or desired.

It is a further object to provide a very simple device, and one which may be manufactured atlow cost from simple parts, and which will have great durability.

Other objects and uses of the invention will appear 3 from a detailed description of the same, whichconsists in the features of construction and combinations of parts hereinafter described and claimed.

In the drawings:

Figure 1 shows a longitudinal section through the power plunger unit and through the corresponding main valve unit, and this figure also shows the short hydraulic connections between the main valve unit and the power plunger unit; and in this figure the power plunger unit has just completed its rightward movement, thereby uncovering the pressure liquid port leading to the right-hand end of the main valve unit, so that immediately after the instant depicted in this figure the main valve will be reversed to produce leftward movement of the power plunger element; and in the position shown in this figure the liquid release port leading from the left-hand end of the main valve has also been uncovered to allow the aforesaid main valve movement to occur without hy draulic lock; and Figure 1 may be considered as a section taken on the line 11 of Figure 2, looking in the direction of the arrows;

Figure 2 shows a longitudinal section at right-angles to that of Figure 1, and may be considered as a section taken on the line 22 of Figure 1, looking in the direction of the arrows; and

Figures 3, 4, and 6 are cross-sections taken on the lines 3-3, 44, 5--5 and 6--6 of Figure 1, looking'in the directions of the arrows;

Figure 7 shows a vertical longitudinal section through the alternative embodiment of my present invention; and in this figure the right-hand plunger element has just completed its rising power stroke so that the port for delivery of pressure liquid to the right-hand end of the main valve has opened, and immediately after the attainment of the position of parts shown in this figure the main valve will be shifted leftwardly to reverse the plunger operations;

Figure 8 shows a vertical longitudinal section at right angles to the section of Figure 7, and is a section taken on the line 88 of Figure 7, looking in the direction of the arrows;

Figure 9 shows an irregular cross-section taken on the line 99 of Figure 7, looking in the direction of the arrows; and

Figure 10 shows a cross-section taken on the line 10-10 of Figure 7, looking in the direction of the arrows.

Referring first to Figures 1 to 6, in the embodiment therein shown I have provided the two aligned power cylinders 21 and 22, and the corresponding compression cylinders 23 and 24 which are also aligned with such cylinders 21 and 22. Thus all four cylinders are located in alignment according to well understood practice in the design of opposed cylinder units. In the design shown inthese figures the two compression cylinders 23 and 24 are of larger size than the corresponding power cylinders so that compressive effects may be produced which are of proportionately less values than the available liquid pressureswhich actuate the power cylinders. Conveniently all four of the cylinders are formed from a single casting 25 bored to the desired finish sizes for the cylinders.

A reciprocating plunger-piston element is located in the element 25. This plunger-piston element includes the two plungers 26 and 27, connected together by the rather small stem28; and the pistons 29 and 30 which work in the compression cylinders are carried by the ends of the plungers 26 and 27, respectively. These pistons are shown as being provided with piston rings according to conventional practice. There is a dividing partition 31 located centrally of the section which comprises the two power cylinders, and such partition is conveniently anchored to the power cylinders by the pin 32 so that the partition is retained against endwise movement in the power cylinders, and provides a stationary abutment against which the pressure liquid acting in the power cylinders may react. (See Figure 4.) The compression cylinders 23 and 24 are closed by the cylinder heads 33 and 34, respectively; and inlet and delivery ports and passages for the refrigerating medium are provided in connection with these cylinder heads. The two inlet passages are designated as 35 and 36, respectively, and the corresponding delivery passages are designated as 37 and 38, respectively; and suitable check valves, 39, 40, 41 and 42 are provided in these passages, acting to allow flow of the refrigerating medium in the proper directions, as well understood. Thus the reciprocations of the plunger-piston unit produce alternate inflows of the refrigerating vapor and deliveries of the compressed vapor according to well understood operations. The inlet and delivery passages for the two compressor cylinders are suitably connected to the refrigerating system as desired.

Inlet-outlet ports 43 and 44 are provided for supply of pressure liquid to and delivery of liquid from the two power cylinders under control of the main valve element 45. These ports are located at the proximate inner ends of their respective power cylinders and close to the partition 31.

The main valve element includes the reciprocating piston valve 46 working in the cylinder 47. The ends of such cylinder are closed by the heads 48 and 49. The power cylinder port 43 connects to the two spaced apart ports 50 and 51 of the valve cylinder 47; and the power cylinder port 44 connects to the two spaced apart ports 52 and 53 of such valve cylinder. These connections are established by the two Y-shaped connectors 54 and 55. The two ports 51 and 53 are release or delivery ports through which the liquid is delivered from the two power cylinders after the successive power strokes; and the two ports 50 and 52 are supply or inlet ports through which the pressure liquid is fed to the power cylinders during the successive power strokes. Conveniently the two supply ports 50 and 52 are spaced apart sufliciently to accommodate the two release ports between them as shown. Other arrangements might be substituted in place of such port sequence, according to the desires of the designer.

The valve cylinder is provided with other ports 56, 57, 58 and 59 corresponding to the ports 50, 51, 52 and 53, respectively. In the arrangement shown said ports 56, 57, 58 and 59 are located opposite to the corresponding ports 50, 51, 52 and 53, as a matter of simplicity of design. Also, the two ports 57 and 59 are conveniently merged together into one large port (measured in the direction of valve movement), since these two ports are both for liquid release and may thus be brought together physically. The cylinder block 47 for the valve is provided with a short transverse passage 60 which leads to both of the ports 57 and 59. Conveniently a removable plate 61 is set onto the valve cylinder block at the general location of the ports of said block. This plate is provided with a rather short longitudinal passage 62 which has its ends in connection with the ports 56 and 58; and a short transverse passage 63 connects to such passage 62. Thus such passage 63 is connected to the ports 56 and 58. The passage 63 is the pressure liquid supply passage and the passage 60 is the liquid release passage of the entire unit.

The valve member 46 is provided with the two annular grooves 64 and 65 which are spaced apart as shown in Figure l. The spacing between these annular grooves is such, and said grooves are so located with respect to the several ports which said grooves serve, that by reciprocating the valve element 46 back and forth a distance substantially equal to the distance between the ports 50 and 51 (or 52 and 53) the desired reversal of liquid connections for control of the supply of power liquid to and release of liquid from, such power cylinders is efiected. These operations are as follows:

With the valve element 46 in its right-hand position, shown in Figures 1 and 2, the annular groove 65 establishes connection between the ports 58 and 52, for admission of pressure liquid, to the space between thev abutment 31 and the left-hand end of the power plunger 27. With the valve element 46 in such position the annular groove 64' establishes connection between the ports 51 and 57 for release of liquid from the space between the right-hand end of the power plunger 26 and the abutment 31. (It is noted that the parts are shown in Figures 1 and 2 in the condition theyoccupy at completion of the rightward movement of the power plunger elements and just before the valve element has been reversed, as will be presently explained.) Study of the relative connections which are established when the valve element 46 has been shifted leftwardly to carry its annular groove 64 into connection with the ports 50 and 56, and the annular groove 65 into connection with the ports 53 and 59 will reveal that the pressure liquid and release connections have been reversed as compared to their previous relations to the two inner ends of the power plungers 26 and 27.

The back and forth movements of the valve element 46 are produced hydraulically in proper harmony with the conclusions of the corresponding shifts of the power plunger elements. To this end I have made the following provisions:

A liquid pressure connection is established from the port 63 to a location adjacent to the inner end of each of the power plungers when such plunger has completed its outward or power stroke. For this purpose I have provided the conduit 66 leading to two lateral conduits 67 and 68. These in turn are connected to the ports 69 and '70 formed in the outer end portions of the power cylinders 21 and 22, respectively. Companion ports 71 and 72 are formed in the power cylinders opposite to such ports 69 and 70, such companion ports 71 and 72 connecting with short passages or conduits 73 and 74 which lead to the outer end portions of the valve element 47 at locations beyond the extreme moved positions of the valve element 46.

The power plunger 26 is provided with the two annular grooves 75 and 76 near its inner and outer ends, respectively; and the power plunger 27 is provided with the twoannular grooves 77 and 78 near its inner and outer ends, respectively. With the power plunger unit in its extreme right-hand shifted position, as shown in Figures 1 and 2, the groove 77 of the plunger element 27 establishes connection between the ports 70 and 72 for admission of pressure liquid to the right-hand end face of the valve element 46. This will produce a force tending to shift such valve element leftwardly to reverse its produced connections. It is noted that such conditions exists with the parts in their positions as shown in Figures 1 and 2, so that immediately after establishment of the condition shown in said figures, and without further movement of the power plungers, the valve will be reversed.

The reversing movement of the valve element 46 can only occur under the pressure developed as above explained by permitting release of liquid from the opposite end of such valve element 46. Such release for valve movement in either direction is permitted by the following arrangements:

l have provided in the lower (inward) portion of each of the compression cylinders 23 and 24 an outwardly extending flange, being the flanges 79 and 89. These flanges are of size to nicely accommodate the plunger ele-- ments 26 and 27, but it is noted that the parts are so proportioned that when each compression piston is at its inwardly moved extreme it comes close to the corresponding flange end 79 or 80 as the case may be, but such flange does not prevent the desired full stroke to be pro-- duced. The laterally outwardly extending passages 81. and 82 are formed in or close to the corresponding flanges 79 and 80, respectively, and these passages have their inner ends connected to the passages 73 and 74, respectively. Said passages 81 and 82 connect with the ports 83, and 34 formed in the flanges 79 and 80, respectively,

so that normally suchports. 83 and 84 aresealed by the power plungers ridingwithin such flanges. Thus, norr'n'ally no flow of liquid from either the pressure liquid supply. passage 67 or 68, as the case may be, or from the corresponding outer end of a valve element may occur through such passage 81 or 82, as the case may be.

The flanges 79 and are also provided with the ports 85 and 86 corresponding to the ports 83 and 84. Also, the power plungers 26 and 27 are provided with the annular grooves 76 and 78 near to their corresponding compression pistons. The arrangement is such that when the power plunger-compression unit is in its extreme righthand position as'shown in Figures 1 and 2 the annular passage 76 establishes connection between the ports 83 and 85 to allow release of liquid from the left-hand end of the valve element 46. At the same time, the annular groove 77 establishes connection between the ports 7th and 72 to allow pressure liquid to act against the right-hand end of such valve element. Thus, in the positionshown in said Figures 1 and 2 where the power plunger-compressor piston element has reached its right ward limit of movement, the valve element 46 will be quickly shifted leftwardly, thus reversing the pressure liquid and liquid release connections to the inner ends of the two power plungers and causing such power plungers to immediately tend to shift leftwardly with corresponding compressor effects. Study of the relations of the parts will show that at conclusion of the leftward movement of the power plunger-compressor piston element the several annular grooves will have come to locations such as to reverse the position of the valve element 46 at the correct time and cause driving tendency to shift the power plunger-compressor element again rightwardly. Thus the desired alternate back and forth movements of the said element will be produced. It is also evident that the reversals of the valve element 46 are produced by hydraulic pressure, and at times and in synchronism with the back and forth movements of the power plungercompressor piston element. The valve movements are produced under hydraulic pressure and with such force as is produced by the projected areas of the valve'element 46 against which such hydraulic pressures are exerted, so that very quick shifts of the valve element will occur. Furthermore, as soon as the valve element has thus been shifted the power plunger-compressor piston element will commence its reversed movement, thus promptly carrying the annular grooves of the plunger elements away from registry with the ports which they had controlled. Thus a hydraulic locking of the valve element 46 will be produced, holding such valve element in its so-shi'fted position, until completion of the movement of the power plunger-compressor piston element in such direction. Then reversal will again quickly occur and be followed by such operations as just explained.

It is noted that at each shift of the valve element 46 as just explained there is released and delivered from the port 85 or 86 as the case may be an amount of liquid equal to. that displaced by such shift of the valve element. This liquid will be received in the corresponding cylinder 23 or 7.4 behind the piston thereof, and must be disposed of. To this end I have provided the return ports 87 and 88 in the walls of the corresponding compressor cylinders. Such released liquid will be delivered through these ports, and such ports may be connected to the return side of the hydraulic system for reuse or re-circulation in the well understood manner.

During the back and forth movements of the compressor pistons there will be produced corresponding displacements behind such pistons and within the respective cylinders 23 and 24. Accordingly, I have shown the breathing openings 89 and 90 in the upper inward end portions of such cylinders through which such breathing actions may occur. 7

It is especially noted that the embodiment shown in Figures 1. to 6, inclusive is one in which all of the passages 7 between the valve unit and the power cylinders are very short and direct. Due to this fact the mass of liquid moving through any given passage at the instant of valve reversal is small, so that very quick shut-offs may be produced without production of noticeable hammer efiects.

' Referring now to the embodiment shown in Figures 7 to loinclusive, in this case I have provided the two power plunger cylinders 89 and 90 in which reciprocate the power plungers 91 and 92, respectively. The compressor pistons 93 and 94 corresponding to these power plungers are connected to their respective plungers by the rods 95 and 96 in alignment arrangement so that the power plungers and their compressor pistons reciprocate in unison. The compressor pistons work in their compressor cylinders 97 and 98, respectively. These cylinders are conveniently closed by the head plate 99; and the inlet ports 100 and,101, and the delivery ports 102 and 103, are provided in such head plate. Check valves 104 and 105 are provided in connection with all of these ports to ensure movement of the refrigerating medium in proper manner through the cylinders. Conveniently the power plunger-compressor piston elements are located parallel to, each other and vertically as indicated in Figures 7 and 8. In such case the lower ends of the power cylinders may be set into and carried by a base section 106 of width and length to provide the needed stability.

I provide a horizontally extending reciprocating valve element 107 in a corresponding valve cylinder 108 of the base section. This valve cylinder extends clear through the base section endwise thereof, and the ends of such bore are conveniently closed by the plugs 109 and 110. A pressure liquid supply port 111 at one side of the base section connects by a passage 112 with the passage 113 which extends parallel to and slightly to one side of the valve cylinder. A liquid release port 114 at the opposite side of the base section connects directly to the short passage 115 which is also parallel to but close to the valve cylinder. In fact, this passage 115 conveniently merges with the valve cylinder as shown in Figures 8 and 10. The base section is provided with the inlet ports 116 and 117 in position to communicate directly with the lower ends of the two power plunger cylinders, and with the release ports 118 and 119 in position to also communicate with the lower ends of the power plunger cylinders. The passage 113 extends far enough to connect to the two liquid pressure ports 120 and 121 for the two power cylinders. These ports 120 and 121 are located in lateral alignment with the corresponding inlet ports 116 and 117 for the two power cylinders. The end portions of the passage 115 extend laterally far enough to be in lateral alignment with the corresponding release ports 118 and 119 for the two power cylinders.

The valve element 107'is provided with the annular grooves 122 and 123 spaced apart as shown in Figures 7 and 10. It is noted that both of the release ports (comprising the end portions of the passage 115) lie closer together than the two inlet ports 120 and 121 so that the two release ports are located between the two inlet ports. The two annular grooves 122'and 123 are spaced apart a distance substantially equal to the distance between the inlet port of one cylinder and the release port of the other cylinder. That relation exists for both combinations of inlet and release ports when the valve element 107 is shifted into either of its two positions. In Figure 7 the valve element 107 has been shifted to its rightwardposition, bringing its annular groove 123 into registry with the pressure inlet port'121 and the inlet port-117 for the cylinder 90; and in such valve element positionits annular groove 122 has been brought into registry with the release port (left-hand end of the passage 115) and the release port 118 of the cylinder 89. Accordingly, in such valve position the power plunger 92 will be forced up' and the power plunger 91 will be allowed to descend,'each in its cylinder. It is here noted that in Figure 7 the right-hand power plunger 92 has been forced up to its extreme position of movement, and the left-hand plunger 91 has been allowed to descend to its lowermost position.

The downward or restoring movements of the two power plunger-compressor piston elements may be produced in any convenient manner, as by gravity. However, it is desirable to provide means to definitely control such downward movements. In the embodiment now being described such means takes the form of springs individual to such units. To this end the following structures are provided:

Surrounding the lower portions of the stems and 96 of the two power plunger-compression piston elements are the compression springs 124 and 125, respectively. T he lower end of each such spring bears against the upper end of the corresponding power plunger. The upper end of each such spring bears against the lower surface of a flange element 126 or 127 as the case may be, such flange elements being connected to the corresponding power cylinder structures. For reasons to be presently explained I have provided an upwardly extending collar on the lower end or floor of each of the compression cylinders, these being the collars 128 and 129, respectively. The flange elements 126 and 127 are provided with downwardly extending nipples 130 and 131 which are threaded into the corresponding collars 128 and 129 so that said flange elements may be adjusted up and down with respect to the collars, and thus also with respect to the cornpressor cylinders and the plunger-piston elements working in them. Thereby the amount of pre-loading of such springs may be adjusted as desired or needed for the intended operations. Such adjustments may be conveniently made by use of a spanner Wrench working in the notches 132 formed in the outer edges of the flange elements as well shown in Figure 9 in particular. Such a spanner wrench may be introduced from above by removal of the head plate 99, or from below as convenient. In this connection it will presently become apparent that I have provided openings in the lower ends of the compressor cylinders for breathing purposes, and such spanner wrenches may be introduced and operated through such openings, if desired.

It is to be noted that such spring return assistance arrangement, when used, will serve to cushion the upward movements of the power plunger-compressor piston elements, and aid in bringing such elements to rest at their top positions. This will materially reduce or eliminate shock during rapid running of the unit. By proper design of such springs, using soft springs, pre-loaded so as to produce a positive intercept of their characteristic curves, a sufficiently uniform reaction may be produced by such springs during the full stroke so as to not materially interfere with the intended compressing action.

I have provided hydraulic means to effect the back and forth reciprocations of the valve element 107 synchronously and harmoniously with the vertical reciprocations of the two power plunger-compression piston elements. Such means is as follows:

Conduits 133 and 134 connect from the end portions of the base sections valve passage 108 to the walls of the power plungers cylinders at locations such that the up and down movements of said power plungers effect connection of said conduits with pressure liquid supply conduits or with release conduits as required. To this end Ijhave provided the ports 135 and 136 in the power plunger cylinders at locations below the lowermost posia conduit 139 which extends down to and connects with the pressure liquid passage 113 so that pressure liquid is always available at the ports 137 and 138. Each of the power plungers is provided with an annular groove near its lower end, being the grooves 140 and 141 for the two plungers, respectively. These grooves are so located in the respective plungers that as each plunger reaches substantially its highest position its annular groove establishes connection between its port 137 or 138, as the case may be, and the corresponding port 135 or 136, thus also establishing connection of the pressure liquid conduit 139 to the corresponding end of the valve cylinder 108 and producing hydraulic pressure against the proximate end of the valve element 107. Thus, there is produced the desired tendency to shift the valve element 107 in corresponding direction. At the same time liquid must be released from the opposite end of the valve cylinder 108 to permit such valve element to shift and prevent hydraulic lock. This result is accomplished by the following arrangements:

Above each of the ports 135 and 136 of the power plunger cylinders there are also provided the ports 142 and 143. These ports are so located that aseach power plunger reaches substantially its lowermost position of reciprocation such port 142 or 143, as the case may be is uncovered by the running of the top face of such plunger to a sufficiently low position. This immediately establishes connection from the outer end of the valve cylinder 108 to such space above such power plunger and allows liquid to be released from such outer end portion of the valve cylinder to a location above such power plunger. I have already referred to the upstanding collars 128 and 129 within the lower portions of the compression cylinders. These provide support for the adjustable fianges 126 and 127 already explained. The liquid released through the ports 142 and 143 will be received within these collars and around the stems 95 and 96, collecting within such collars until the surface of such collected liquid reaches to the elevations of openings 144 and 145 formed in such collars. Thereupon further liquid delivered into the collars will move out through such openings and run down into the lower portions of the compressor cylinders. These compression cylinders are connected to the power plunger cylinders by the floors 146 and 147, respectively. Openings of substantial sizes 148 and 149, are provided in these floors and such sodelivered liquid will move down through such openings to the location of the base section 106. From such location such so-delivered liquid may be returned to the circulating system and re-used on a cycle basis.

Promptly upon the shifting of the valve element 107 the passage connections will be altered to introduce the pressure liquid to the lowered power plunger-compression piston element and commence upward drive of the same. This will at once cause the port 142 or 143, as thecase may be, to be closed so that the valve element 107 will be hydraulically locked at its then position. It will remain so locked until the plungers have attained their contra positions to again produce alteration of the port controls. It is to be noted that although the two power plunger-compression piston elements of the embodiment now being discussed are not physically connected together by positive mechanical means they are hydraulically locked together so that they cannot get out of step from each other. This must be apparent from the following:

The reversal of the valve element 107 requires that pressure liquid be introduced against one of its ends, and also that liquid be released from its other end. The delivery of such pressure liquid to the first named end requires that one of the plunger-piston elements be at its fully raised position (in order to efiect connection from the conduit 139 to the conduit 133 or 134, as the case may be); and the release of liquid from the other end of the valve element 107 requires that the other plunger-piston element be at its fully lowered position.

Thus, to eifect shift of the valve element 107 both of.

these prime conditions must me complied with. If one of the plunger-piston elements should attain its terminal position prior to the attainment of terminal position by the other plunger-piston element, as will generally be the case if even for a fraction of a second, valve shift cannot occur until the other plunger-piston element has attained its terminal position to complete the requirements and satisfy all prime conditions. Thus the leading plungerpiston element will be held for a short interval until the other plungeppiston element has caught up and attained synchronism with its companion.

It will be noted that in the embodiment of Figures 7 to 10, inclusive, both the power plunger cylinders and the compressor piston cylinders are rigidly connected by attachment to the common base section. Additionally, I have shown a construction in which the two compressor piston cylinders are themselves formed as an integral unit.

Conveniently a light shell is extended between the base section and the lower portions of the compression piston cylinders so as to provide a chamber within which the liquid flowing down through the openings 148 and 149 may collect. the circulating liquid system, and re-used.

I claim:

1. A compressor unit including in combination a pair of cylinder elements each including a power cylinder and a compressor cylinder in axial alignment each with the other, a power plunger-compressor piston element for each cylinder element and including a power plunger working in the power cylinder and having a driving fluid pressure surface and a compressor piston working in the compressor cylinder of such unit and having a driven fluid compression surface, means connecting together the power plunger and the compressor piston of each power plunger-compressor piston element and constituted to retain said elements a fixed separation axially from each other, the power plunger and the compressor piston of each power plunger-compresson piston element being in axial alignment each with the other, and being reciprocable between a first terminal return position and a second fully moved power stroke position, pressure liquid supply and liquid release port means in each power cylinder adjacent to the first defined position of the power plunger of such cylinder, together with main valve means for the device, including a cylindrical valve chamber, a plungerlike valve element reciprocably mounted in said valve chamber and reciprocable between first and second power cylinder control positions, said valve chamber including a pressure liquid supply connection and a return liquid delivery connection, and also including a pressure liquid delivery port for each power cylinder and a return liquid port for each power cylinder, conduits connecting the liquid delivery port and the return liquid port of the valve chamber which correspond to each power cylinder to the pressure liquid supply and liquid release port means of such power cylinder, respectively, the plungerlike main valve element being formed to establish liquid flow connection from the pressure liquid supply connection to the pressure liquid delivery port of the valve chambet for one power cylinder and to seal the return liquid port of the valve means corresponding to such power cylinder when the plunger-like main valve element is in its first defined cylinder control position, and being formed to establish liquid flow connection from the return liquid port corresponding to the other power cylinder and to seal the pressure liquid delivery port of the valve means corresponding to such other plunger cylinder when the plunger-like main valve element is in said first defined cylinder control position, and said plunger-like main valve element being formed to establish liquid flow connection from the pressure liquid supply connection to the pressure liquid delivery port of the valve means for said other power cylinder and to seal the return liquid port of the valve means corresponding to such other power Such liquid may then be returned to.

its second defined cylinder control position and beingfprmed to establish liquid fiowconnection from the re-. turn liquid port corresponding to the first mentioned p wer cylinder and to seal the pressure liquid delivery port, of the valve means corresponding to such first mentioned power cylinder when the plunger-like main valve element is in said second defined position, together with means to shift the plunger-like main valve element from its first defined power cylinder control position to its second defined power cylinder control position when the first mentioned power plunger-compressor piston element is in its second fully moved power stroke position and the second mentioned power plunger-comprcssion piston element is in its first mentioned terminal return position and to shift said valve element from its second defined power cylinder control position to its first defined power cylinder control position when the second mentioned power plunger-compressor piston element is in its second fully moved power stroke position and the first mentioned power plunger-compressor piston element is in its first mentioned terminal return position, said valve element shifting means comprising a first port in the wall of each power cylinder, individual valve control conduits extend ing from the main valve chamber at points beyond the first and second power cylinder control positions of the reciprocable valve element to the corresponding power cylinder first ports aforesaid, valve operating pressure liquid supply second ports in the walls of both of the power cylinders opposite to the corresponding power cylinder first defined ports, respectively, the first defined and second defined ports of each power cylinder being located farther from the first defined terminal return position of the driving fluid pressure surface of the power plunger working in such power cylinder than the fully moved power stroke position of such driving fluid pressure surface of such power plunger, a conduit in each power plunger of form to establish communication between the first and second defined ports of the power cylinder corresponding to such plunger when such plunger is in its fully moved power stroke position, pressure liquid supply conduits in connection with said second defined, ports last mentioned, valve operation liquid release third ports in the walls of both of the power cylinders, at locations farther from the first defined terminal return position of the corresponding power plungers than the corresponding first defined and second defined ports of the, power cylinders, a conduit connecting each third defined port with the valve control conduit for the power cylinder which corresponds to such valve control conduit,

and each power plunger being formed to uncover the corresponding third defined port only when such power plunger is at its first defined terminal return position.

2. Means as defined in claim 1, wherein the cylindrical valve chamber extends. substantially parallelto the axis of reciprocation of the power plunger-compressor piston and the cylinders of atleast one of the cylinder elements, and wherein the valve control conduit for the proximate end of the. valve chamber connects to the power cylinder of such cylinder element.

3. Means as defined. in claim 1, wherein both of the cylinder elements first defined lie in axial alignment with each other, and wherein all of the power plunger elements and corresponding compressor piston elements reciprocate on said axis, of alignment, and wherein all of said elements are axially connected together.

4. Means as defined in claim 3, wherein the cylindrical Valve chamber lies substantially parallel to the axis of alignment of the cylinder elements, and wherein the end portions of the valve chamber are in proximity to corresponding power cylinders, and wherein the individual valve control conduits extend between the end portions of the valve chamber and the proximate power cylinders.

5. Means as defined in claim 1,, wherein the cylinder elements first defined lie. parallel to each other and in proximity to each other, and wherein the valve chamber extends in direction substantially at right-angles to the axes of the cylinder elements, and wherein the reciprocations of the power plunger-compressor piston elements are physically independent of each other, together with spring means urging each power plunger-compressor piston element towards its first terminal return position.

6. Means as defined in claim 5, together with means to adjust the spring force of each such spring means.

7'. Means as defined in claim 6, wherein said spring force adjusting means for the two power plunger-compressor piston elements are independently adjustable in amount.

8. Means as defined in claim 1, wherein each power cylinder is provided with a fourth port in its wall opposite to its third defined port aforesaid, and wherein the formation of the corresponding power plunger by which formation such power plunger uncovers the corresponding third defined port only when such power plunger is at its first defined terminal return position comprises a conduit within such plunger having fluid transmitting parts adapted to register with both of the corresponding third defined and fourth defined ports only when such plunger is substantially at its first defined terminal return position.

References Cited in the file of this patent UNITED STATES PATENTS 2,143,179 Baker Ian. 10, 1939 2,579,670 Hjarpe Dec. 25, 1951 2,642,045 Potts June 17, 1953 FOREIGN PATENTS 2,611 Great Britain June 15, 188]

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