US 1258462 A
Description (OCR text may contain errors)
R. H. RICE.
APPLICATKON man APR. 15. 1915.
1,258,462. Patented Mar. 5, 1918.
UNITED STATES PATENT OFFICE.
RICHARD H. RICE, 0F LYNN, MASSACHUSETTS, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.
Application filed April 15, 1915. Serial No. 21,519.
To all whom it may concern:
Be it known that I, RICHARD H. RICE, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Centrifugal Compressors, of which the following is a specification.
The present invention relates to impellers for centrifugal compressors and particularly to the construction and arrangement of the entrance buckets which direct the incoming fluid to the vanes that impart velocity and more or less pressure to the fluid passing therethrough.
By entrance bucket I means the inlet portion of the impeller vane which receives the fluid and directs it to the main portion of the vane. In the course of the following specification I shall refer to the main portion of the impeller vane as the vane and to the entrance portion thereof as the entrance bucket.
The object of the invention is to provide an impeller of improved construction for high speed centrifugal compressors, and is directed particularly to the means employed for securing the individually formed entrance buckets in place on the impeller whereby they will be well anchored against centrifugal stresses, and at the same time will be restrained from destructive vibration or fluttering.
For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.
Referring to the drawing wherein I have illustrated one form which my invention may take, Figure 1 is a side view of a portionof the impeller of a centrifugal compressor; Fig. 2 is a radial section through a portion of the impeller as shown in Fig. 1; Fig. 3 is a top plan view showing adjacent entrance buckets in place on the impeller; Fig. 4 is a perspective View of one of the entrance buckets; Fig. 5 is a section on line 55, Fig. 3; Fig. 6 is a detail view showing a modification; Fig. 7 is a detail plan view of said modification, and Fig. 8 is a detail side view of the same.
6 indicates the shaft of a centrifugal compressor, and 7 the impeller vanes carried by the web member 8, said vanes being radially disposed and for example integral with the web. The web member is shown as being formed in two parts-the line of division being in a vertical plane through its centerand formed integral with each part is a hub 9. Each part of the impeller with its vanes is cast as a unit, after which the various surfaces are machined to their proper dimensions. The impeller is carried on the shaft by the snug fitting rings 10 and the sleeves 11 over which the outer ends of the hubs slip. Only one sleeve 11 shows in the drawing, but it will be understood that the one at the other end is similar. The impeller is shown of the balanced thrust type which receives fluid at both sides near its axis, discharging it at the periphery, as is well understood. 12 is a bucket supporting ring which is tightly fitted over the end of the hub and is provided with spaced undercut slots 12' one adjacent each vane, and into which the bases of the entrance buckets fit. Each entrance bucket comprises a dovetailed base 13 of a size to fit the diagonally extending and undercut slots 12, on which is supported the body member 14; which forms the entrance bucket proper, said member being suitably shaped to guide the entering air into the spaces between the vanes 7. As shown, each bucket base is made in the form of a dovetail, but this can be varied to suit the requirements. The main thing is to provide a base of such size and shape that it will, when inserted in a corresponding slot, anchor or retain the bucket in place against centrifugal stresses. On the peripheral edge-of the body member on the side next to the vanes is one or more cars 15, preferably two, which fit over the side edge of and are attached to the adjacent vane by suitable pins or rivets 15. The top of the body member is also pro- Patented Mar. 5, 1918. 1
vided with circumferentially extending projections or members 16 and 17 forming a head. 'When the entrance buckets are assembled, the heads of adjacent buckets abut against each other to form a continuous ring, as best shown in Fig. 1. The purpose of these heads or projectionsis two-fold. First they serve to stilfen the buckets against'the stresses to which they are subjected, and second by firmly contacting with each other at their adjacent ends they prevent vibrations of the buckets, which vibra: tions if unrestrained and permitted to continue long enough might result in cracking or breaking the buckets near their bases. If
rilull the ends of these heads or projections are permitted to move slightly, one on the other, they would in time be so worn that the buckets would be relatively loose at these points and as a result vibrations could take place which would increase as the vvear continued and might result in injury to the buckets as aforesaid. Furthermore it should be noted that even if the heads are tight when the impeller is stationary, they might,
become loosened to a certain extent by centrifugal stresses when the impeller 1s 1n operation. As the bases 13 have either curved or inclined straight edges, and fit into diagonal slots in the ring 12, the abut. ting faces of the heads are shaped to correspond; This permits the buckets to be slipped into place one after the other and be.
wedged into place. I further prevent inde: pendent movement of the bucket heads, both axially and radially, by providing one or more circumferential grooves 18 in the pe- The binding wire or band has three principal functions: First, itacts as a damper to prevent vibration or fluttering of the buckets, it being understood that when a body is in a state of vibration even a slight pressure or friction suliices to stop it; secend, it assists in some orall cases in carrying the load on the bucket bases'by -relieving them of a certain amount of load, and" in this sense acts like a self-supporting ring,
and third as, the bucket bases and heads occupy diagonal positions as distinguished from axial positions the; band prevents the heads from working out of line. It will be understod, of course, that the relative sizes of the parts 16 and 17 as related to each other may be considerably varied, the head or projection being formed wholly on one side should it be found desirable. After the entrance buckets are assembled in place a ring 21,as shown in Fig. 2, is heated and shrunk on over the hub of the impeller to' hold the supporting ring'12 in place and also prevent thebucket bases from working out of their dovetail grooves or slots. The hub and ring 21 are provided with interlocking shoulders, as shown at 22;
' By the above described arrangement I provide a very strong and rigid structure of entrance buckets and one whichis capable of withstanding high centrifugal. forces,
. buckets when said buckets are to the impeller vanes. 1 The members 16 and 17 form lateral support for adjacent buckets and are very firmly held in relation to each other by the binding wire. This eflectively prevents fluttering or vibration of the buckets.
As before stated, the projections 16 and 17, when the. buckets are assembled, form a continuous ring around the outer peripheral edge of the entrance buckets. Instead of forming this ring of a series of separate, elements carried by the respective buckets, ll may form it as a single separate self-sustaining ring and after the buckets are assembled fasten it in position, as by means of, heating and shrinking it into place. Such an arrangement is shown in Fig. 6 where 24: indicates the outer or peripheral edges of the buckets and 25 the ring surrounding the same. The ring 25 is provided with diagonal slots or grooves 26 in itsinner surface into which the milled edges of the buckets snugly fit as best shown in Figs. 7 and 8, and the ring and buckets are also formed with interlocking shoulders 27 By this arrangement the buckets are firmly fastened against lateral movement or vibration and otherwise braced. r 7
The forces-exerted on the entrance buckets during operation of the machine may be and usually are considerable and for this reason it is desirable that the buckets be of substantial strength.v By forming them separate from the supporting ring and attaching them thereto, as by the dove-tailed arrangement shown, I am enabled to form the buckets of a good grade of. material well adapted for the purpose and one which 7 maybe different than that of the supporting ring. For example it permits of the buckets being made of drop-forgings. Furthermore the arrangement described permits of making the body of the impeller 8 and its vanes 7 out of a still difl'erent material: when desired. To state the matter in another way, the use of a three piece arrangement enables me to utilize the best material for each part, due consideration being given to the stresses to which the parts are subjected and also to the character of the machine work required in their manufacture. I desire to particularly emphasize the fact that each entrance bucket is supported at the bottom, asby the base 13 for example, at the to as by the cars 15 for example, and at'an intermediate point, as by the. projectionsor head 16- and.
1? for example, the latter being held by the mutual cotipera-tion of the heads of adjacent assembled in position. I
1 ln accordance with the provisions of the patent statutes, l have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof;
but I desireto have it understood that the apparatus shown is only illustrative, ad that the invention can be carried out by other means.
What I claim as new and desire tofsecureby Letters Patentcf the United States, is .'e
1.. In a centrifugal compressor; the-combination of a shaft, an impeller mounted there on comprising a hub and radially extending vanes anchored at their radially innet" ends,
a radially extending entrance bucketassociated with each vane for directing fluid to such vane, said entrance buckets being carried by the hub and the vanes appurtenant thereto, and means for preventing vibrations of the outer ends ofsaid entrance buckets.
2. In a centrifugal compressor, the combination of a shaft, an impeller mounted thereon comprising a hub and radially extendin vanes anchored at their radially inner en s, a supporting ring carried by the hub said ring having a slot adjacent each blade, and a radially extending entrance bucket associated with each vane for direct" ing fluid to such vane, said entrance buckets having bases which engage said slots and are anchored by the walls thereof, and means 7 acting on the outer ends of the buckets to prevent vibration thereof.
3. In a centrifu al compressor, the combination of a shaft, an impeller mounted thereon and provided with vanes, a supporting ring having spaced slots carried b the hub of the impeller, separately formed entrance buckets having bases which engage and are anchored in said slots, means for fastening the entrance buckets to adjacent vanes, and means formed on the outer ends of the buckets which contact one with the other to prevent vibrations.
l. In a centrifugal compressor, the combination of a shaft, an impeller mounted thereon and provided with vanes, a supporting ring having diagonally arranged slots in its periphery, said ring being mounted on the hub of the impeller, separately formed entrance buckets whose bases enter said slots and are anchored therein, and means for fastening each of the entrance buckets to its corresponding vane.
5. In a centrifu al compressor, the combination of a shaft, an mpeller mounted thereon having radially extending vanes anchored at their radially inner ends, and a hub which projects beyond the vanes, a supporting ring mounted on the projecting portion of the hub, a radially extending entrance bucket associated with each vane for directing fluid to such vane, said entrance buckets having bases which are attached to said rings, and ears which engage thevanes "appurtenant thereto, and means carried by the buckets for preventing vibration of the outer ends thereof.
'7 6. Ina centrifugal compressor, the combi nation of a shaft, an impeller having vanes mounted thereon, means containing undercut slots spaced around the hub of the impeller, entrance buckets having bases which fit into said slots and projecting ears which engage adjacent vanes, and pro ecting members carried by the entrance buckets, said members being in contact with and mutuall supporting each other.
7. iln a centrifugal compressor, the combination of a shaft, an impeller having vanes mounted thereon having a hub which pro- Lects axially beyond the vanes, entrance uckets having individual bases, means for attaching the bases to the projecting portion of said hub, ears on the entrance buckets which engage adjacent vanes, projecting "members carried by the entrance buckets and making contact 1n a circumferential direction, and means for preventing relative motion of said 'rojecting members.
8. In a centrifugal compressor, the combination of a shaft, an impeller having vanes mounted thereon, entrance buckets having bases which are attached to the hub of the impeller and ears which engage adjacent vanes, projecting members carried by the entrance buckets which engage each other to form a continuous surface, and a binding.
a shaft upon which the impeller is mounted for rotating it, and a plurality of individual entrance buckets rotating with the impeller and shaft, each bucket being supported at its top and bottom and also on each side by adjacent buckets.
In witness whereof, I have hereunto set my hand this 13th day of- April, 1915.
RICHARD H. RICE.