US1041511A - Centrifugal compressor and pump. - Google Patents

Description

R. H. RIOE & S. A. MOSS. GENTRIFUGAL COMPRESSOR AND PUMP. APPLICATION FILED I'EB.8, 1907.

1,041,511 1 Patented Oct. 15,1912.

3 SHEETS-SHEET 1.

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6 8 l8 5 24' l7 7 2/ E -1 ;;:i i=5+ I 4 m IN 1 I d c? l. v... T V f 1121-3" 20 Inventors:

Richard FLRa'ce,

Sanfbr'd a Moss,

E. H. RICE & S. A. MOSS. GENTRIFUGAL COMPRESSOR AND PUMP.

APPLICATION TILED FEB. 8, 1907.

Patented Oct. 15, 1912.

3 SHEETS-SHEET 2.

Inventors: Richard H.Rice San-Ford Mo WiLnessesz' Patented 00t.15,1912.

3 SHEETS-SHEET 3.

R. H. RICE & S. A. MOSS. OENTRIFUGAL COMPRESSOR AND PUMP.

APPLICATION I'ILBD rmm, 1907.

Witnesses:

RICHARD H. RICE AND SANFOBD MOSS, OF LYNN, MASSACHUSETTS, ASSIGNOBS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAE COMPRESSOR AND PUMP.

Specification of Letters Patent.

Patented Oct. 15,1l9l2.

Application filed February 8, 1907. Serial No. 356,327.

To all whom it may concern: 7

Be it known that we, RICHARD H. Bron and SANFORD A. Moss, citizens of the United States, both residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Centrifugal Compressors and Pumps, of which the following is a specification.

The present invention has for its object to improve the construction of centrifugal compressors and pumps, particular reference being made to the means for receiving and directing the passage of fluid into the receiving ends of the impeller blades and to the construction of the impeller blades and the support therefor.

Other. features of the invention will be pointed out in the description and claims appended'thereto.

In the accompanying drawings which illustrate one of the embodiments of the invention, Figure 1 is a view in elevation of an electric motor direct coupled to a centrifugal compressor, the latter being in section; Fig. 2 is an end view of the'compressor withcertain of the parts broken away; Fig. 3 is a partial section of the impeller showing how the blades are secured in place by casting the. metal of the body around them; Fig. 4 is a section taken on line 4 4 of Fig; 3; Fig. 5 is a section taken on line 55 of Fig. 3; ,and Fig. 6'is a'hgzontah section of the compressor. l

1- represents an electric motor, the re volving n ember of which ismounted on the' shaft 2. The motor shown is of the alternating current type, but any other form of motor can be used. On'one end of the motor casing is formed or attached a neck or projection 3 containing a bearing 4 of substantial dimensions and having feet 5 adapted'to be secured to a'foundation. The main portion of the motor casing is also provided with supporting feet. The right-hand end of the neck terminates in a vertical wall 6 which forms a part of the casing of the compressor and is provided with a shaftreceiving opening. This wall is provided with a shoulder 7 near the periphery to receive the annular wall 8 formed on the lefthand half 9 of the casing of the compressor. The two are secured by axially-extending bolts which are readily accessible. The arrangement described has the advantage-of reducing the number of the parts, the

low such curves that the incoming in width toward the periphery. O

' circle,

amount of machine work involved, and it eliminates the troubles incident to the lack of alinement. It also has the further advantage that the inlet and discharge conduits can be set at any desired angle 'to connect with the piping system. This is accomplished by equally spacing the holes in the shoulder 7 and those in the lugs on the annular wall 8 which receive the axiallyextending bolts so that the parts can be angularly adjusted.

The impeller 10 is mounted ori the shaft 2 and is overhung with respect to the main bear-mg 45', the opposite end of the shaft being located in albearingtcarried by the "lefthand head of the motor. The impeller is held in place on the shaft by suitable means, including the nut 11, and can be taken off by vremoving said nut. The main body of the impeller comprises a steel casting having a hub 12 ofsuitable proportionsland a web 13 which gradually tapers in thickness toward the periphery. The sides of the hub, it will'be observed, are cut away and folfluid particles are caused to follow a path which directs them radially to the inner ends of jectionableeddies and losses due to friction. Extending through the web 13 from side to side are blades .14. These blades are provided with openings or perforations to receive molten metal, when the body is cast, and the metal located in said openings and extending circumferentially serves to hold the parts of the body together against burstthefluid-conveying passages between the blades. At a point just beyond the periphery of the impeller provision is made to receive the annular nozzle 15 which converts the impeller blades, thereby preventing obmg strains and also to hold the blades Boththe into the radial direction. It is desirable to make the diameter of these orifices as large as possible so that the velocity of the ntering fluid will be low and hence the losses due to cross-currents and eddies reduced to a minimum. On the other hand, the diameter of the orifice should be less than that of the circle forming the path of the inner ends of the blades so that the particles of the incoming fluid will be properly directed f'and all have the same, or substantially theSame, direction and velocity; Our experience has-demonstrated that if a compressor is to have a high degree of effi- 'ciency, the fluid must. be freely moving when first acted upon by the .blades, and without cross-currents or eddies. It is desirable to extend the inner ends of the blades as near to the shaft as possible, for structural reasons, hence a compromise is effected between the diameter at the inner ends of the blades and the diameter of the fluidreceiving orifices 17.

As it is important to supply the fluid undergoing compression as freely as possible to all parts of the orifices, each half of the casing is provided with an axiallyextending wall which is located at some considerable distance from the orifices. at all points so as not to offer any opposition to the flow. As an example, \annular walls 8 and 20 "have beenshown since they are the easiest to machine. The right-hand annular supply chamber 18 is closed in by a detachable end wall 19 that is bolted to the annular wall 20. The center of the wall '19 is provided with aboss 21 hai'ing a well rounded base to prevent-the fluid from striking the nut on the end of the shaft. The left-hand annular su ply chamber is closed in by the wall 6 asbe ore described. In Fig. 6 the compressor is shown in section,.' at right angles to that of Fig. 1. Fluid enters the inlet 22 and then divides, one half going to the annular chamber on one side and the other half to the annularchamber on the opposite side. The fluid is discharged from the scroll or collecting passage 16 through the opening 23 Fig. 2. From this figure and also the ones previously described it will be seen that the cross-sectional area of this passage gradually increases from one end to the other.

Where for any reason it is necessary to pack the shaft 2 Where it passes through a plurality of partitions into a ring 25 that is seated on a shoulder 26 formed in the casing. The opposite sides of the partitions may be connected or unconnected as desired. As shown they are unconnected and rest on the inclined port-ion 27 of the casing. Since the nozzle is annular the arrangement shown will, when the" parts of the casing are bolted together, hold it without other means. The nozzle shown is so constructed that the passages 28, Fig. 2, between the partitions-expand from the inlet toward the outlet, and by such an amount as will convert the velocity of the fluid discharge from the impeller int-o pressure, thereby appreciably increasing the efliciency of the apparatus. 1

The air leaves the impeller at apressure considerably above atmosphere owing to centrifugal action along the impeller blades. It also has a high velocity due to the rotation of .the impeller. This velocity represents practically one-half of theenergy put into the air by the impeller, the remainder being represented by the centrifugal pressure. In the usual fan blower this velocity and energy are wholly lost in eddies in the collecting passage or scroll. By the introduction of a nozzle having discharge vanes as described, a considerable portion, of the energy represented by the velocity is converted into pressure, thereby giving an appreciable gain in pressure and efliciency.

Referring now more especially to Figs. 2 to 5, inclusive, the specific construction of the impeller will be described. The blades 14 are made out of relatively thin sheet steel and gradually taperin width'from the inlet or lower end, Fig. 4, to the upper'or discharge end. They are also curved somewhat from end to ,end' -so that the air isturned in a definite and gradual manner.

In the blades are punched a number of holes 30 gradually increasing in size toward the shaft. Generally speaking, the size of the holes increases'with the increase in thickness of the web. In the inner end of each blade a recess 31 is. formed, also by the punching process. The object in making a recess instead of a hole is so as not to unduly weaken the met-a1 in the web at this point because the strains are high. It is important to prevent the lower ends of the blades from bending outwardly or distort-' ingdue to centrifugal stresses. .To prevent this, PI'OJGCt-IORS 32 are provided on the inner ends of the blades. It will be observed that the larger of the holes have small points or projections 33; these are left when the stock is cut out byround punches and are desirable since they assist in holding the parts. There is or may be a greater or less fusion between the cast metal in the body of the impeller and that of the blades. Considering the sheets when assembled about the shaft, the holes or perforations 30 therein and the recess 31 are arranged in concentric circles, the diameters of which increase from the shaft outwardly. The portions 30 which are integral parts of the main body and are formed when the casting is made serve two purposes: First they serve to prevent the wheel from bursting due to centrifugal strains, and second they anchor the blades against all strains andalso preserve their alinement. It will be noted in the present illustration that six concentric portions 30 are provided for securing the parts, but the number can be increased or decreased. It is also to be noted that the cross-sectional, area of said portions decreases as the distance from the shaft increases. Two or more of the outer portions may however have the same'cross-section. In order to make the impeller as light as 7 possible, yet at the same time strong, the

metal at the periphery of the body is cut away leaving project-ions ig l, Fig. 2, one in front and one in the rear of each blade. In other words, the periphery of the body is scalloped and the sheets forming the buckets extend-through the points thereof so that each blade at its outer endis braced front and back. These projections or points on opposite sides of 'the blades are united by the outer portions 30 of the main body. We further lighten the impeller by omitting side plates therefrom and depend upon the walls of the impeller casing to form the sides of the fluid-carrying pas- .sages. Besides materially decreasing the weight and the strains incident to such reduction, the open .construction enables the sides of the impeller body to be readily finished. It will be observed that the blades extend-entirely through the body of the impeller from oneside to the other. By reasonv of this the use of independent sets of lades oneach side of the impeller is avoided, thereby reducing the number of parts, the loss due to waste in material, and the cost of manufacture. Again the blades being of substantial size are more readily shaped and castinto place. An impeller constructed as described will also be exceed ingly strong and have a large factor of safety, which is an important consideration in a machine of this kind adapted for-high speeds. The impeller will also be balanced as to thrust because it draws its supplies of fluid in equal amounts from opposite sides. It will be seen that the fluid enters in multiple streams andis discharged into a nozzle and scroll common thereto. By experience' we have learned that the centrifugal forces of such an impeller are great enough when of the proportions shown to bend over the inner ends of-the blades. To avoid this, notches are cut in the edges of the blades and mounted therein are rings.35, one on each side of the body. They are held in place by staking, as at 36. Rings are used because they are of simple and reliable construction, but other devices may be used. These rings arepreferably thin in the direction' of flow of the fluid undergoing compression, so as not to ofler undue opposition. The entrance and exit to theimpeller are so arranged as to keep the air in a homogeneous stream.

The machine described will deliver air at a substantially constant pressure at a given speed, which pressure can be varied by changing the speed of the driving shaft. There will be a slight falling off in pressure when the amount of'air delivered is comparatively small and also when the amount of air delivered is comparatively large, but for all practical purposes the pressure may be said to be independent of the amount. actually delivered. 7 V

By substituting an impeller for the one shown having blades with different entrance and exit angles, the machine'can be made to deliver fluid at a higher or' a lower pressure as desired, the shaft speed remaining the same;

One of the principal advantages of the compressor shown resides in the fact that a lar e portion of the energy can be added centri lgally to the fluid passing through it in a highly etlicient manner. By preference only a I comparatively small amount of energy is added to-the fluid in the form of kinetic energy, since the efliciency with which this can be converted intov pressure 7 energy is comparatively low. a

The compressorshown 1s mtendedtocompress 3.11701 other. aseous fluids, or 1t may be used as a centri gal pump for pumping liquids.

In accordance with the 'provisions of the patent statutes we have described the principle of operation of our invention, together -with the apparatus which we now consider to represent the best embodiment thereof; but we desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. V

What we claim as new and desire to secure by Letters Patent of the United Stat 38, 1s,-

' 1. In an apparatus of the character described, the combination of an impeller having blades on opposite sides of the body thereof, a casing, the walls of which inclosc the blades on the impeller and are provided with orifices, one in'each side, through which the fluid enters, the surfaces of said orifices being well rounded and arranged to direct which receive uid from the impeller, convert its velocity into pressure, increase its density and discharge it into the scroll.

' 2. In an apparatus of the character described, the combination of a motor, an impeller driven thereby, a casing for the impeller having a discharge conduit, a projection on the -motor with which the casing is united and is angularly adjustable thereon, a supply chamber located between one end of the projection and the casing, and a second supply chamber located on the opposite side of the impeller.

3. In an apparatus of the character described, the combination of a motor, an im-,

peller driven thereby, a casing for the impeller having a discharge conduit, a projection on the motor for uniting it with the casing, a wall located on one side of the easing; and cooperating with the projection to form a chamber, walls on the opposite side of the casing arranged to form a chamber, and a conduit for supplying fluid to the chambers.

4;. In an apparatus of the character de-' scribed, the combination of a motor, an impeller driven thereby, a casing for the impeller, a projection on the motor for uniting it with the casing and forming a w ll of a supply chamber, a wallcooperating withthat supported by the projection and with the casing to form a supply chamber, and conduits for supplying fluid to the chamber and receiving it after passing through the impeller.

5. In an apparatus of the character described, the combination of a motor, an impeller driven thereby, a casing for the impeller, a projection on the motor for uniting perforated sheets of metal extending from the axis outwardly to form blades and ait with the casing and forming a wall of a supply chamber, a wall cooperating with that supported by the projection and with the casing. to form a supply chamber, walls on the opposite side of the impeller cooperating with the casing to form a second supply chamber, means for supplying fluid to the chambers,.and a scroll which receives thefluid .after it passes through the impeller.

6. An impeller comprising a cast metal body portion and sheets of metal cast therein, the latter extending through the body 66 to form blades on opposite sides thereof having uncovered edges, and -means which.-

- parts of the body together at different distances from the axis and resisting centrifu gal strain. 1 T

8. An impeller comprising a cast metal body portionand perforated sheets of metal extending through the said body and forming buckets on opposite sides'thereof, each sheet having a plurality of perforations gradually decreasing in size as the distance from the axis increases, and integral portions of the body which extend through the perforations and form concentric anchoring meansthat also resist the tendency of the body to disrupt due to centrifugal strains. 3 i

9. An impeller comprising a plurality of sheets of metal having irregularly-shaped perforations to receive inolten metal when the body portion is cast, and a cast body portion which is of less width than the sheets so that the latter will form blades on opposite sides and which is provided with a hub portion having cut-away sides that are thinner in an axial direction than in the part receiving the sheets to assist in directing the entering fluid.

10. An impeller comprising a cast metal body and a plurality ofmetal sheets that extend through the body and form blades on opposite sides thereof having uncovered edges, and means for tying the edges of the blades together near their inner ends to re-. sist the effects of centrifugal force.

11. Animpeller comprlsing a cast metal body and a plurality of metal sheets that extend through the. body and form blades on opposite sides thereof having uncovered edges, and rings located'on opposite sides of the body a d seated in notches in the blades and secured in place by staking.

-12..An impeller comprising a plurality of,

body of metal of less widththan the sheets and into which they are ca'st'with portions of thebody extending through the perforations, the said body being scalloped at the outwardly diverging passage the impeller to confine the fluid between the blades, and whose integral outer portions form a scroll, said casing and scroll being divided in the plane of the impeller, a shoulder formed on the inside of one part of the casing and locatedadjacent to the scroll, a wall formed on the inside of the opposite portion of the other part of the casing which is beveled outwardly from the impeller, said wall forming one side of anozan annular nozzle surrounding the impeller in the plane thereof which rests on the shoulder and is held in place between it and said wall when the parts of the casing are united, said nozzle comprising an out-, wardly beveled side member which coiiperates with the beveled side wall to form an for the fluid discharged by the impeller, and tangentially arranged straight sided partitions forthe nozzle that are supported at their edges by the member and said beveled wall, said partitions rapidly increasing in width, measured axially, as the distance from the impeller increases, integral; annular walls on the outside of the halves of the casing, covers secured to the annular walls to form with them supply chambers on each side of the impeller, an inlet for supplying fluid to the chambers, and a discharge conduit communicating with the scroll.

- 14. An impeller comprising a cast-metal body, perforated sheets of metal that are carried by the body and extend outwardly from the axis and on both sides to form blades, each of said sheets having a recess at its lower end with a restricted opening,

and means formed integral with the body which fill the recess and the perforations and serve to prevent the body from disrupting and also to anchor the sheets.

15. An impeller, comprising a cast metal body with relatively thin blades supported thereby and having free outer edges, each of said blades having a curved inlet portion and a radially disposed discharge portion which forms a continuation of said inlet portion and is tangentially arranged with respect thereto, and a ring which is attached to the inlet portion of each of said blades near itsv inner end to prevent said portions from bending under centrifugal stresses.

16. An impeller, comprising a body with blades supported thereby on opposite sides and having free outer edges, each of said blades comprising a curved inlet portion and a radially disposed discharge portion which forms a continuation of the inlet portion and is tangentially arranged with respect thereto, said blades being wider, measured axially, at their inlet ends than at their discharge ends, sides of the body and attached to the curved inlet portions only of the blades to prevent them from bending overdue to centrifugal stresses.

In witness whereof, we have hereunto set our hands this fifth day of February, 1907.

RICHARD'H. RICE. SANFORD A. MOSS.

Witnesses:

JOHN A. MCMANUS, Jr., HENRY O. VVESTENDARP.

and rings located on opposite

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