US2280100A - Fluid pressure apparatus - Google Patents

Description

F. D. SINGLETON FLUID PRESSURE APPARATUS ,Filed Nov. 3, 1939 April 21, 1942.

fizz/26210. J" z'lzglefoiz INVENTOR VBY I fizewz TTORN Y Patented Apr. 21, 1942 Del.

one-half to Fred C. Mitchell, Wilmington,

Application November 3, 1939, Serial No. 362,708 3 Claims. (01. 230-79) I This invention relates to improved fluid pressure apparatus and, more particularly to improvements in apparatus of the type containing a rotor, enclosing case and sealing fluid adaptable. for

creating compression or suction.

Various proposals have been previously made of compressors, motors and the. like in which compression or suction has been effected by movement of a rotor, having a helical or spiral blade, in a body of liquid, or by movement of the body of liquid on orbetween the helical or spiral blades of the rotor. r

There have been various disadvantages in the practical application of such previous proposals,

however, including such difiiculties as those of: obtaining an economical and suflicient overall volumetric efficiency; overheating of the appa ratus due to friction and heat of compression; obtaining uniform suction or pressure, due to back discharges through the liquid entrained in the helical passages; maintaining the desired and correct level of sealing fluid, and the like. It is an object of the presentinvention to overcome these and other disadvantages and to provide a new and improved apparatus adaptable for f gaseous or liquid compression or suction. v

Other objects and advantages of my invention will be apparent by reference to the following specification in'which the preferred embodiments are described;

The apparatus of my invention comprises an improved form of rotary compressor or suction pump in which the rotor is in theform of a conical screw, forming a helical passage or passages with a portion of each of its spirals submerged in a body of liquid, and eccentric within an enclosing case containing a liquid. The rotor of my invention, being eccentric within the case and having details and agitating or driving means around its outer face, carriesliquid within the case around with it as the rotor revolves. At the same time, each convolution of the rotor being only partly submerged in the liquid, there is formeda pocket of air or other gas which is thus forced fromone end of the rotor to the other. Inasmuch as the rotor is in the form of a conical screw, and inasmuch as'the helical convolutions are reduced in width as they approach the outlet end, thecapacity of the passages become less and less and theconsequent pressure greater and greater toward the outlet end of the rotor. l g

According to one ofthe features of myinvention, tliis general type of apparatus is improved and made more efficient by constructing the heli-- cal threads of therotor in a V or U shape, 1. e.l to the low pressure end) and the velocity attained with a. rounded "bottom to the helical groove.

have found that by use of suchconstruction the,

sealing fluid is displaced in such a way that a more effective seal is obtained'andtherefore the volumetric efiiciency isincreased,

As a furtherfeature of my invention, there; are providedpickuptubes, withinthe enclosing-casing, which carry ,a. part of, the sealing liquid througha heat exchange unit for removal of the heat caused by friction, and/orcompression of the gaseous fluid and thereafter return the fluid to the j enclosing casing; In returning thissealingliquid to the enclosing casing, it is first introduced into the hollow rotor, from whence it passes outthruports or nozzles provided for the purpose, thru the l gaseous fluid beingcompressed, and returns to. the

main body of sealing liquid,

The parts or nozzles in the rotor are designed to breakup the sealing liquid, which passes .thru' them, into a flat spray and to direct this spray, in].

a direction tangent to the periphery of the rotor.

and opposite to the direction of rotation. The

advantages of this feature are described in greater detail hereinafter. i

f cooling mediumthereby approximating isothermal compression of the gas; it provides a, means of absorbing one or more components of agaseous. i

I is presented to the gases being compressed a quan-W tity or series of relatively stationary sprays which largely prevent the frictional rotation of the gases and thereby largely reduce leakage under the and, since in a machine of this general type there r and sealing liquid on the one hand and the gases being compressed'on the other, and sincethe jet velocity of the discharge of sealing liquid from the tangential rotor ports or nozzles equals or:

; The removal of sealing" liquid; for 1 cooling and returning in this way, accomplishes four definite improvements in the overall efficiency and/or. utility of the machine, 1. e.,- it provides ,a means for maintaining a uniform controlled temperature within the machine; it providesia means. for com pressinggases while in intimate contact with a mixture into the sealing fluid during compression;

is a relative rotating motion between the rotor exceeds the perinherial velocity of the rotor, there rotor seal and increase volumetric eiiiciency.

that there is ordinarily a tendency for the gas to be forced back against the liquidseal, from onestage or convolution to another (the high pressure inside of said case.

by the gas results in appreciable loss of pressure in the high pressure end before this action stops. According to my invention, however, a check valve or check valves are incorporated at the discharge end of the compressor so that only that gas which may be entrained in the helical passage is able to leak back, thus producing an automatic unloading and constant pressure action within the compressor.

As a further feature of this invention which,

together with those features previously described,

increases greatly the smoothness of operation and efficiency of the rotor, I have provided an automatic means for discharging the sealing liquid upon stopping the compressor and for maintaining the correct level of sealing liquid during operation of the compressor. These automatic features are accomplished, according to my invention, by means of a spring-loaded diaphragmoperated, two way valve which is so placed in connection with the pick-up tubes for recirculation and cooling of the sealing liquid that, during normal operation of the compressor, sealing liquid is directed through cooling coils, from the internal portions of the enclosing case, and back to the As the speed and/or pressure decreases, however, the diaphragm valve is operated so as to retard or stop this flow of liquid through the cooling means andjthe liquid is forced into a storage receiver, which is in turn so positionedas to give a head of liquid at a higher level than thatof the interior of the enclosing case.

The'preierred details and embodiments of this invention will be made clear by reference to the following description, when taken with the accompanying drawing in which Figure 1 is a central sectional View through one form of my improved apparatus; Figure 2 is a cross section of the rotor of Figure 1-, the section being made at 11 as indicated in Figure 1; and Figure 3 is a diagrammatic sectional view showing the helical threads and automatic valves of my invention.

Referring to Figure 1, the machine consists of a rotor [revolving eccentrically within an outer casing 2 which in turn is mounted on bearings 3 and free to revolve. The rotor I has a continuous spiral fin or fins-4 forming a conical spiral passage or passages progressively decreasing in pitch as the rotor increases in diameter, which entrain the gaseous fluid to be compressed. The case 2 carries a sealing fluid 5, the gaseous fluid to be compressed entering at 6 and discharging at 'I.

The fins 4 which form the spiral or helical passages for entraining fluids to be compressed are thickened at the base, where they join the, main body of the rotor, to form U shaped passages.

Referring to Figure II, which is a cross or I transverse section thru rotor I, outer case 2, and

sealing fluid 5, the normal position of the sealing'liquidsurface is shown at 8, the direction of rotation being clockwise. Since'in this general type of machine there is a relative plunging and receding motion between the rotor fins t and sealing liquid and since in my design the bases of these fins 4 are thickened or broadened, there is created at the point 8 a greater than normal displacement of sealing liquid causing the liquid surface to curve inward for ashort distance as indicated, 9. This causes a region of increased sealing liquid pressure against rotor I near this point, assisting the sealing liquid in preventing the fluid III which is being compressed, from leaking under the rotor seal, which action produces an increase in the volumetric efficiency of the machine.

Aflixed to the outer periphery of fins 4 are a series of blade 33, with the side of greatest dimension presented to the direction of rotation. These blades impartenergy to sealing fluid 5 to cause rotation of the body of fluid in the direction of rotation of rotor I. The resulting centrifugal force causes the sealing fluid to assume the shape of an annular ring within the outer casing 2.

Referring to Figure 1, there are enclosed within the outer casing 2 a tube or tubes II in a stationary position with the open end or ends facing the direction of rotation. Due to the kinetic energy of the rotating sealing liquid 5, which is produced by centrifugal force and impact against the open ends of the pick-up tubes II, the sealing liquid is forced thru passages I2 to a heat exchanger I3 and back thru passages I I to a hollow annular space I5 within the rotor I. If heat exchange is not desired, the fluid from pick-up tubes II may be directly passed, by means not shown, to the hollow annular space I5. A sealing ring IS with suitable anti-friction facing I I is provided where the liquid passes from the stationary tubes I l to the rotor space I5. The rotation of the liquid while within the rotor space I 5 imparts additional energy which assists in forcing the liquid thru ports I8 to nozzles I9 (Figure II) from where it is sprayed thru the fluid III which is being compressed. Figure II illustrates the tangential sprays 20 from these nozzles I9. By this movement of liquid the heat of compression is removed from the fluid It as it is formed, thereby producing isothermal compression which not only increases the overall efficiency of the machine but makes it possible to compress gaseous fluids which have a tendency to decompose upon increase of temperature. The heat is dissipated from heat exchanger I3 by circulating a cooling fluid thru tubes 2| and 22 or 1by any other convenient means of heat dissipaion.

As shown in Figure II, nozzles I9 produce a flat spray tangential to the surface of the rotor I and backward with respect to the direction of rotation. In this type of machine there is a rapid rotating motion of the surfaces of the rotor I relative to the fluid I II which is being compressed. The sprays 20 present a relatively stationary surface forming a series of bafiles to prevent the rotation of fluid I II which is being compressed, thereby largely preventing leakage of the fluid I0 under the rotor seal and increasing volumetric eii'iciency of the machine.

Again referring to Figures I and III, a check valve, or valves, 23 allow compressed gases to escape from the rotor passage thru ports 24 but prevent a backward discharge, i. e., from the high pressure end of the machine back to lower stages of compression. Since a backward discharge due to over-compression beyond that pressure for which it was designed will result in a progressive expansion of the compressed gases in a backward direction and, due to the gas velocities reached, coupled with a considerable volume of gas in the high pressure end which must be dissipated before the action stops, a considerable amount of sealing liquid may be blown out thru the low pressure end of the machine and in any event a considerable loss of compressed gases is eifected. According to my invention, valves 23 prevent any gases blowing back except those within the rotor passages, which. do not exist in sufiicient volume to sustain a blow-back for a harmful period of time. Actually a balance of tank 21.

pressures is reached within the rotor passages to the extent that a more or less continuous blowback occurs, the alternate compression and decompression of gases in the rotor passages taking place rapidly, (decompression only partially) resulting in only a part of the normal amount of compression, and therefore only a part of the normal power, being used, which constitutes an automatic unloading of the machine.

As shown in Figure I a system of piping 25 i and automatic diaphragmor other pressure actuated valve 26 together with a storage tank 27 may be utilized according to my invention. A valve 26 is so adjusted and connectedthat during normal operation the flow of sealing liquid thru the tubes I2 is directed to a heat exchanger 13. However, when power is removed fromthe machine and it reduced speed, there is resultant drop in static pressure of sealing liquid, and in the valve 26 a corresponding reductionin pressure on the diaphragm 23, allowing a spring 29 to move the valve and stop the flow of sealing liquid to the heat exchanger l3, directing it to a pipe 25 which in turn carries it to a storage tank-21 In this way the major portion of the sealing liquid is removed from the machine when it is shut down and thus prevented from over- 5 or 1 respectively.

A pipe 30 acts as a drain from storage tank 2! and terminates in an open end 3| inside the a conical screw, the helical convolutionson the rotor forming, between the convolutions, a U-shaped helical trough progressively decreasing in pitch as the rotor increases in diameter, at least one outlet from the hollow casing leading to a hollow annular spacewithin the rotor, ports leading from the hollow annular space within the rotor to the U-shaped trough formed by the helical convolutions, a series of vanes afiixed to the outer periphery of the rotor convolutions, with their side of greatest dimension presented tothe direction of rotation, and a valve governing the outlet for compressedfluid from the high pressure end of the rotor and adapted to allow for- F ward but toprevent backward flow of compressed fluid through the rotor.

2. An apparatus adapted for rotary compres+ sion comprising a freely revolvable hollow casing,

machine and at the low pressure end, with the opening facing against the direction of rotation. When the machine is started and a valve 32 is opened there is a flow of sealing liquid into the case 2 which continues until the inner surface of the annular ring of sealing liquid 5 reaches the level of the tube opening 3|, at which time impact pressure of the liquid 5 against the tube opening 3| stops the flow thru tube30.

Should the surface of the sealing liquid 5 for any reason submerge the tube opening 3| to the extent that theresulting impact pressure becomes greater than the static head pressure from the storage tank 21 there will be a reversed flow in tube 30, returning sealing liquid to the storage This provides an automatic means of maintaining a constant level of sealing liquid 5 within case 2.

Blades 33 act upon sealing fluid 5 to produce movement of this fluidwithin the outer casing 2 and in the direction of rotation of rotor I. Centrifugal forcecauses the sealing fluid 5 to assume By maintaining this rotation of fluid containing a body of liquid, with inlet and outlet means, a revolvable rotor Within and eccentric to the axis of the casing and havingthe form of a conical screw, the helical convolutions on the rotor forming, between the convolutions, a U-shaped helical trough progressively decreasing in pitchas the rotor increases in diameter, at least one outlet within the hollow casing facing counter to the direction of rotation of the rotor and leading to a hollow annular space within the rotor, ports leading from the hollow annular space within the rotor to corresponding nozzles affixed to the U-shaped trough formed by the helical convolutions, a series of vanes afiixed to the outer periphery of 'the rotor convolutions with their side of greatest dimension presented to the direction of rotation, and a valve governing the outlet for compressed fluid from the high containing a body or liquid, with inlet and outlet Q means, a revolvable rotor and eccentric to the axis of the casing and having the form of pressure end of the rotor and adapted to allow forward but to prevent backward flow of compressed fluid through the rotor.

3. An apparatus adapted for rotary compression comprising a freely revolvable hollow casing containing a body of liquid, with inlet and outlet means, a hollow revolvable rotor within and eccentric to the axis of the casing and having theform; of a conical screw with helical convolutions on the rotor forming, between the convolutions, a U-shaped helical trough progressively decreasing in pitch as the rotor increases in diameter, at

least one stationary outlet within the hollow casing with an open end facing counter to the di rection of rotation of the rotor, heat exchange means connected with at least one stationary.

outlet within the hollow casing and connected to a hollow annular space within the rotor, a series of ports leading from the hollow annular'space Within the rotor, a series of nozzles connected to the ports and afiixedto the trough formed by the U-shaped helical convolutions and pointing in a direction counter to vthe direction of rotor rotation, a series of vanes aflixed to the outer periphcry of the rotor convolutions with their side of greatest dimension presented to the direction of rotation, and a check valve governing the, outlet for compressed fluid from the high pressure end of the rotor and adapted to allow forward but to prevent backward flow of compressed fluid through the rotor. i

FRANCIS D. SINGLE'I'ON,

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