US1443764A - Compressor - Google Patents

Description

3 SHEETS-SHEET l f ATT.

Jan. 30, i923. ,443,764

H. J. SMITH. COMPRESSOR. Fl LED JUNE 7, 1920. 3 SHEETS-SHEET 2 vwwwfoz Kaza/.'mi thi 5512* /ZZJ @Holme/1J Jan. 30, 1923.

H. J SMTH. COMPRESSOR.

3 SHEETS-SHEET 3 FILED JUNE 7, 1920.

3512* his m CIN Patented dan. 3@ 1923.

tarea aria.;

IHAZORJ. SMITH, OF CHICAGO, ILLINOIS, ASSIGNOR, BY DIRECT AND EL'ESNE ASSIGN- MENTS, OF ONE-FOURTH TO WILLARD REID AND ONE-HALF T0 ALIKRED HASTINGS CEAPIN, BOTH OF SPRINGFIELD, MASSACHUSETTS.

COMPRESSOR.

Application led VJune 7, i920. Serial No. 387,2e8.

To all whom t may cof/wem.'

Be it known that l, HAZOR J. SMrrH, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Compreors, of which the following is a specification.

This invention relates to compressors of the type used in refrigerating systems of the private dwelling type, and more specifically, relates to a compressor having a series of compression chambers for the cooling gas and means for cooling and separating the lubricating oil used therein.

The invention consists essentially of a two stage pump having two or more pairs of meshing helical gears, similar gears of each pair being mounted on one shaft; a differential pressure being applied to the motor driven gear shaft whereby itI is kept lubricated without the lubricant escaping; an escape for thegas and oil from the meshing gears just prior to complete meshing whereby no back pressure results; and means for separating the oil from the gas after compression.

The preferred embodiment of my invention l have illustrated in the accompanyin drawings in whichy Fi-gure 1 is a vertical sectional view through the compressor on a line transverse to the gear shafts.

Fig. 2 is a longitudinal verticalv section along line A-A of Fig. 1.

' Fig. 3 is a longitudinal vertical section along line B-B of Fig. 1.

Fig. 4 is a composite View showing the arrangement of the gears. Figs. 5 and 6 show modified forms for cooling the oil.

Referring now by reference characters to the drawings, the compressor consists mainly of a housing 1, a face plate 2 upon which is assembled the spacing elements 3, 4, 5 and' 6 held in axial alignment by the boltsl. ln the gear pocket, between members 3 is a pair of helical gears 7 and 8 in mesh each keyed to its respect- ive shaft 11 and 12; gear 7 on the idlerl shaft 12, and the gear 8 on the drive shaft 11. Member 4 serves as a central bearing for the shafts and also provides an integral cross-over passage by which the compressed medium from the top of the initial gears 7 and 8 is delivered to the bottom of the secondary gears 9 and 10 in the gear pocket between members 5. The plate 6 serves as an end bearing for the two shafts 11 and 12 and also as the abutment plate for the gears 9 and 10. As shown the ratio of volumetric capacity between the two pairs of gears is 2 to 1, although any desired ratio may be used.

The drive end of the shaft 11 is protected I against leakage by the gland shown in ldig. 3. lt consists of an adjustment block 14, a gland block '15, gland packing 16 separated by the oiling lantern 17 which takes its oil from the container 18, and. the align-` ment ring 17 a. it will be seen that the inner ends of the shafts are exposed to the pressure of the high side, nominally about l pounds absolute, while atmospheric pressure presses against the outer ends of the shafts. This difference in pressure serves to keep the shafts tightly pressed against the alignment rings 17a and keeps a constant pressure upon the glandpacking which normally is sufficient to prevent leakage of the gland without adjustment of the gland ad-v justment nut lll. Where a machine is to run for a long Aperiod of time without attention it is quite necessary to provide means whereby the pressures of the machines them'- selves sha-ll serve to adjust their glands during periods of inattention. s

In Figs. 6, 5 and 2, is illustrated a method pursued to cure one of'tlfe meanest troubles connected with' the successful operation of gear compressors running at high speeds. Considering that the gears run close to an abutment plate on-each end and also within a close fitting housing it will be seen that if the gears are close. fitting there exists a pocket between the gears and the face plate that has no utlet. This pocket is formed by each succeeding tooth as it reaches that' point in the circle where it meets the Contact surface of the next following tooth lin the opposite gear. If only gas is being pumped it has been found thatl this pocket produces no other apparent effect than to produce a pocket of sufficient internal pressure toforce a leakage of the gas through the mesh line,

through the contact line of the teeth and between the gears and vthe abutment plate.

rlhis takes power and heats the gas but the edect is comparatively small. When, however, oil is used to seal the gear mesh line it will be seen that there is an incompressible body enclosed in a constantly decreasing chamber With no outlet except that produced by pressure forcing the mesh line open or forcing the gears away from the abutment. 'lhe result has been to producean amount of heat and strain on the bearings that make practical operation very diffi-v cult. lllhis, however, is cured by clearing away the abutment plate on the tooth line by the Width of one half a tooth above the mesh line. i

Referring to Figs. 2 and t, the recesses el are cut in the abutment plates d and 6 and fashioned to connect With its contiguous gas passage and approaching,` the center line closely enough to clear the chamber' H.' rl`he positionis indicated as at H but the pocket to be cleared is formed rst on one side of the center line and then on the other according to the tooth coming into mesh. rlherefore the cutout is Wide enough to clear the full Width of a pitch depth. The cham-- bere-d cutout does not go belov,7 the center of the gears.

This relief feature in connection with heli'- cal gear compressors is a very valuabie one because of the power saved. Theelimination of all possible sources of mechanical heat as distinct from the heat of compression of the gas itself produces a highly cihcient combination.

lvlfithout the relief afforded by the recess described, the oil becomes very hot, broken up into a ne mist, and very frothy. rl`he pressure and other combinations cause the oil and the refrigerating agent toblend or mix in such a Way that separationdoes not taire place eiciently. The oil seems to abn soro the refrigerating agent and both circulate. rlhis naturally reduces the capacity of the machine.

ln operation, the course of the compressed medium and the oil Which is used for' sealing the clearance spaces of the gear elements as Well as lubricatingthe mechanism is as follows and it constitutes the unique features of the device described:

Gas from the expander elements or coils enters the compressor at the connection 19. The tension of the low or evaporated. side being held at about llinches of vacuum or about Z pounds absolute, through the control of the expansion valve, (notshown) in the usual manner. "ll rom the passage 19 the gas is carried in the spaces between the teeth of the gears to the top of the gear couple or into the passage or intermediate section 2G where it is left as a' result of the meshing of the gears on the mesh line, each tooth of a gear displacing the gas in the gear opposite. r1Ehe passage 20 is a cross-over to the intake side of the succeeding pair of Lee-ageegears 9 and l0 Where the process of passing around thegears to the discharge side is repeated. F rom the chamber 2l the gas is discharged into the housing chamber 22 Where it passes to and through the separator 23 and finally passes to the condenser through the connection 24. If it Were possible to make gears that meshed perfectly Without any clearance in the root of the teeth a gear pump Would function efficiently Without seal of any kind but it is impossible to so construct gears and therefore a sealing medium is necessary if a high degree of volumetric efficiency is to be obtained. rlhis is accomplished in my compressor by utilizing a stream of oil Which is carried through the strainer a25 on the plate 6, thence through the opening 26 in the shaft 12 to the clearance space in the face plate 2 thence through the passage 27 to the end yof the passage or intermediate section 20 Where it drops into the mesh of the gears at the initial mesh point of the helical teeth.

rlhe lead of the helix carries the oil With e,

the g'along the mesh line of the gears and seals with its high viscosity, the clearance openings of the gears themselves. Unly a small portion of the oil passes through the mesh to the lower side and this is only sufhcient to furnish oil to seal the small clearance between the gear teeth and the Walls of the housing 3. rli`he surplus of oil is carried along the passage 2 0 to the bottom of the high pressure gears 9 and 10 Where itis picked up by the gears and carried around With the gas to the top side and is discharged after sealing the gears along with the gas. Separation of the gas and oil takes place in the chambers 22 and the separater 23.

Fig. 5 shows the arrangement found satisfactory Where it is desirable to carry the oil outside of the'compressor shell for the purpose of cooling it before returning it for use as a seal.l lt will be noted that all three bearings of the shaft l2 are lubricated by the forced feed of the oil in, its passage through the shaft. Bearings of the shaft il are lubricated by the oil passage lla which is fed through the hole 11b in the plate 6. The gland end of the shaft ll. is lubricated by the gradual seepage of oil toward at 'mos'pheric pressure and by the supply in the container 18.

.il 1g. 6 shows the approved form of the device Where 1t seems advlsable to remove the oil separator andcooler from the housingl n The oil 1s passed through a strainer 25 and thence through a coolingcoil and thence bach to the compressor and discharged into the passage 20 through the face plate,'from whence tliedischarge pressure will always be Sullicient to force a flow of oil. A predetermined restriction in the paage at any point between the strainer and the discharge opening into passage 20 will control the amount of oilpassed and prevent an excess in the oil feed. v

While I have shown and described certain specific constructions, I" do not wish to be limited thereto, as they are merely illustrative of the principle of my invention and obviously various modifications may be used without departing from the spirit 0f my 1nvention.

What l claim is:

l. ln a multiple stage gear pump of the type described a plurality of pairs of mesh-y ing gears, no two pairs having the same volumetric capacity, mounted upon two arallel shafts one of which is the drive s aft to which thevgears are radially ixed, but

vaxially movable, all mounted in a suitable housing, a shoulder upon the drive shaft, an aligning ring within a stuting box normally resting against the shoulder of the drive shaft a mass of packing surrounding the shaft, an oiling lantern upon the shaft, aA

secondary mass of packing, an adjustable gland block, means for maintaining a gravity pressure of oil upon the oilinl lantern, and means for maintaining the rive' shaft 1n pressure contact with the alining ring of the stutiiiig box. i

In a multiple stage pump of the type described a plurality of pairs of meshing gears, each pair of gears in stages from low to high having less volumetric capacity than the preceding pair, means for circulating"` an oiling and sealing medium along the faces of the helical gears, means for feeding the oil on top of and at the ends of. the geais, just prior to the point of entry of the oil in the intermediate section, whereby the oiling and sealing medium' is prevented from entering the gas inlet. l

3. ln a multiple staged gear compressor of the type described means for preventing leakage of gas along the drive shaft through the gland when the machine is at rest; and means for preventing the admission of air along the drive shaft through the gland into the compressor when the machine -is in operation, which conisis'ts of an axially mov# The diference inv pressure between the initial intermediate stage andV able drive shaft having a Smallerl diameter through the gland than back of the gland; an oiling ring resting against the shoulder so formed on the shaft; al section of packing material around the shaft; an oiling lantern around the shaft; another section of packing material an adjustable gland nut; a reservoir of oil connected withy the oiling lantern through the' side of the stuiiing box; said 'reservoir 'being adapted to intercept they seepage of oil along the drive shaft when the machine is lat rest and the internal res-` sure of the compressor exceeds atmosp eric pressureand adapted to supply oil to the shaft as a seal when atmospheric pressure exceeds the internal pressure of the compressor, and means for maintaining the drive shaft in pressure contact with the alining ringof the stuffing box. l

4. In a compressor of the type described .a pair of meshing gears mounted on two parallel shafts, one shaft being the drive shaft,

a packing gland, a shoulder provided on the drive shaft, an aligning ring on the inner end of the packing gland normally resting against the lshoulder of the drive shaft, means whereby the difference in pressure between the discharge side yand the atmospheric pressure is utilized to hold the drive shaftin pressure contact with the inner end of the packing gland.

5. ln a multiple stage compressor a plurality of pairs of meshing gears, means for circulating an oiling and sealing medium along the faces of the gears, means for feeding the oil on top of and at the ends of the gears just prior to the exposure of the teeth in their successive discharge position.

6. In a multiple stage pump of the type'- ference in pressure between the discharge pressure. and an intermediate stage to' produce a forced circulation of the sealing medium.

7. In a multiple stage pump, a plurality of pairs of helical gears and housings mount- 'ed upon two shafts one of which is the driving shaft each pair in thel stages from low to high having less volumetric capacity than the pair preceding'and means for utilizing the difference in pressure between the discharge and any intermediate stage to produce a forced circulationof the oiling medium. y

8. A multiple stage pump having an initial inlet pressure, intermediate and final dis-f charge pressures each higher than the pref. ceding and utilizing the difference in pres-f sure between an intermediate and high stages to produce a forced circulation of the sealing` cooling and oiling medium.

9. In a multiple stage compressor of the ioo i Meeres 'type described a plurality of pairs of meshing gears, no two having the seme volumetric capacity, the pairs of gears, means for circule-ting an oiling and sealingmedium along the feces of the gears, means for feeding the oil on top of end :it the ends of the gears just prio? to the point et which the gear tooth arrives et the intermediate section whereby the oiling and sealing medium is prevented from entering the gas inlet.

10. In e multiple stage pump7 pairs oie meshing gears, e shaft carrying one gear oi' an intermediate seetion between( end pressure means for maintaining the shaft pressed againstv the pecking gland.

in testimony whereof 'l aiiix my signa 2@ ture.

HAZUR J. SMMFH.

vfl/'itnesses f lil/'mijnen Rem, R. L'SWENIGEN.

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