US2976011A - Fabricated bladed compressor wheels - Google Patents

Description

March 21, 1961 E. A. STALKER ,0

FABRICATED BLADED COMPRESSOR WHEELS Filed Feb. 10, 1955 2 Sheets-Sheet 1 INVENTOR. 4 amwm March 21, 1961 E. A. STALKER FABRICATED BLADED COMPRESSOR WHEELS 2 Sheets-Sheet 2 Filed Feb. 10, 1955 INVENTOR.

United States Patent 2,916,011 I FABRICATED BLADED COMPRESSOR WHEE Edward A. Stalker, Bay City, Mich., assignor to The Stalker Corporation, a corporation 'of Michigan Filed Feb. 10, 1955, Ser. No. 487,315

4 Claims. (Cl. 25339) This invention relates to bladed wheels for axial flow compressors. I

An object of the invention is to provide a light weight wheel which is economical to fabricate.

Another object is to provide a bladed wheel particularly adapted to relatively small diameters.

2,976,011- Patented Mar.

ice

g 2 Y hole 62. These teeth fit into the flutes 64 between th splines 66 in the cylinder 68. g 'I'hewheels are positioned apart by the rings 65 shown in Figs. 1 and 3.

' Shaft means for driving the wheels comprise end disks 70 and 72 integral with shafts 22 and 24 respectively,

. in the rim means and as shown in Fig. 6 each blade is Other objects will appear from the description, drawings and claims.

The above objects are accomplished by the means illustrated in the accompanyung drawings in which:

Fig. 1 is a fragmentary axial section of a compressor according to this invention;

Fig. 2 is an enlarged fragmentary section of a wheel on line 2--2 in Fig. 3;

Fig. 3 is an enlarged fragmentary axial section of a bladed wheel of the compressor of Fig. 1;

Fig. 4 is a front axial view of a bladed wheel;

Fig. 5 is a side elevation of a blade according to this invention; and

Fig. 6 is a fragmentary section on line 6-'6 in Fig. 3.

In relatively small compressors of the axial flow type, the cost of fabrication is particularlyimportant. cost of the blades can be kept low by employing similar blade sections of equal chord throughout the blade span. Such blades can be economically producedas solid ones by rolling a solid strip of the proper blade section and preferably fixed to the rim means 84 by fillets of solder or fused metal 90, also to the disks by similar fillets 92. Each blade isalso preferably fixed to the front and rear flanges of the rim means by fused metal at 93 and 94.

Stators 100-102 are interposed between the wheels as shown in Figs. 1 and 3. These are preferably supported from the compressor case 12.

Although the invention is particularly adapted to blades of constant blade section throughout it is not limited to 1 these but may be used with any type blade.

The

then cutting to length. To obtain a low cost the blades 71:

should be provided with simple economical means of retention in a wheel. 'Such means isalso provided by this invention.

Referring now to the drawings, a compressor and its components are indicated generally by 10 in Figs. l6.

The'wheel assembly comprisesthe wheels 30-32,. and

since the type of construction is similar for all wheels only wheel 31 will be described in detail.

A fragmentary section of wheel 31 is shown in .Fig.

3.- It comprises the air foil blade portions 40 which are integral with and extend radially outwardly of, rootportions 41, the'blades being peripherally spaced about the hub means 42 with wheel flow passages 43, Fig. 2, between them. In the present instance this means includes one or more disks which are let into slots in the inner ends of the blade roots. Thus as shown particularly in Fig. 3 the disks 44 and 46 each has a radial portion fixed respectively in slots 50 and 52. See Figs. 1, 3 and 5. There are also the intermediate disks 54 and 56 whose outer ends are fixed in slot 58 and whose inner ends are fixed to the inner ends of the disks 44 and 46, preferably by solder or other fused metal between the parts, thus bridging the gap between disks 44 and 46.

As shown particularly in Figs. 1, 3 and 4, each wheel has the teeth 60, Fig. 4, cu in the disk about the central The rim means and the disks are readily made as sheet metal constructions, that is they are readily cut out from sheet stock and formed to shape by pressing with dies. --"Ifhis invention refers to compressor wheels for increasing the static pressure and density of an elastic fluid. In

order to achieve a significant change in density with an axial flow compressor each wheel must be operated at a speed high enough to effect a significant change in density, that is a change which in magnitude is outside the usual order of engineering accuracy'in industry. Thus machines are considered to be compressors as distinguished from fans or blowers at tip speeds of about 400 feet per second or more. At such a speed the average change in density along the blade length is about 3% which is just about the commonorder of accuracy of measurement of the density. Such compressors are expected also to operate at blade tip speeds close to the velocity of sound. At such speeds the change in pressure may be more than 70% or more than 10 pounds persquare inch for air inducted at atmospheric pressure. 6

Since in a compressor'wheel there is a substantial pres.- sure variationrfrom front to rear the ratio of the hub radius to the bladetip radius is relatively large of a value of the order of 0.5 and preferably greater so that the pressure difference between front and rear sides can be sustainedwithout a return flow at the hub such as occurs in a fan... For the same reason the blades are spaced peripherally. close together, preferably about one chord length orless apart.

Commonly :half to all the static pressure change oc:

curs in the wheel between the leading and trailing edges.

To sustain such a change in pressure along the wheel passages from leading to trailing edges of the blades the hub rim between adjacent blades and from leading to trailing edges is a fair and continuous surface. Also at all rotative speeds the case must fit closely about the blade tips which are contoured to the cylindrical surface of the case along substantially the whole tip length of the blade chord.

To diffuse the flow between blades and achieve a pressure change the flow should follow the blade surfaces without eddies. Accordingly the blades should have faired or tapered leading edges. They should have sharpened trailing edges to be efficient.

It is commonly understood in engineering and industry that sheet metal construction is limited to sheets whose planar dimensions are large in comparison to their thicknesses for thicknesses less than about A of an inch. Sheets of greater thickness are called plates. (Steel sheet and plate manufacturers list their product of large planar dimensions of 94 or less as sheets and greater'thicknesses as plates.) Sheet metal constructions are comprised of parts which are formed from sheet material to define the contours of the part in the plane of the sheet, and of such parts which are subsequently given another shape by pressing with a die.

It will now be clear that I have disclosed a novel wheel structure for compressors which is of light weight and economical to produce.

While I have illustrated specific forms of the invention, it is to be understood that variations may be made therein and that I intend to claim my invention broadly as indicated by the appended claims.

I claim:

1. In combination in a bladed wheel for exchanging energy with a fluid, a hub structure comprising a plurality of axially spaced disks having peripherally continuous and imperforate radial outer portions secured together for rotation about the axis of symmetry thereof, a plurality of blades peripherally spaced about said hub structure, each said blade having axially spaced slots each receiving said radially outer imperforate portion of each of said disks thereinto, said blades being fixed to both sides of said outer imperforate portions of said disks by fused metal, and continuous annular rim means defining wheel flow passages between adjacent blades, said rim means being fixed in said wheel at the inner end portions of said blades and extending from one blade to another providing walls bounding said wheel flow passages on the radially inward sides thereof, said rim means having front and rear flanges directed radially inward, the inner end of at least one of said flanges having a radius greater than that of said disks to provide for axial assembly thereover.

2. In combination in a bladed wheel for exchanging energy with a fluid, a hub structure comprising a plurality of axially spaced disks having peripherally continuous and imperforate radial outer portions secured together for rotation about the axis of symmetry thereof, a plurality of blades peripherally spaced about said hub struce ture, each said blade having axially spaced slots each receiving said radially outer imperforate portion of each of said disks thereinto, said blades being fixed to both sides of said outer imperforate portions of said disks by fused metal, and continuous annular rim means defining wheel flow passages between adjacent blades, said rim means being fixed in said wheel radially outwardly of said disks at the inner end portions of said blades and extending from one blade to another providing walls bounding said wheel flow passages on the radially inward sides thereof, said rim means having front and rear flanges directed radially inward and fixed by fused metal to each said blade along the front and rear edges thereof, the inner end of at least one of said flanges having a radius greater than that of said disks to provide for axial assembly thereover.

3. In combination in a bladed wheel for exchanging energy with a fluid, a hub structure comprising a plurality of axially spaced disks having peripherally continuous and imperforate radial outer portions secured together for rotation about the axis of symmetry thereof, a plurality of blades peripherally spaced about said hub structure, each said blade having axially spaced slots each receiving said radially outer imperforate portion of each of said disks thereinto, said outer imperforate portions being fixed to both sides of said blades by fused metal at said slots, and continuous annular rim means defining wheel flow passages between adjacent blades, said rim means being fixed in said wheel at the inner end portions of said blades and extending from one blade to another providing walls bounding said wheel flow passages on the radially inward sides thereof, each said blade having similar blade sections of equal chord lengths over a major portion of the blade length radially outward from said rim means, said rim means having a radius greater than that of said disks and being assembled thereover and located radially outwardly thereof.

4. In combination in a bladed wheel for exchanging energy with a fluid, a hub structure comprising a plurality of disks spaced along an axis of rotation and having peripherally continuous and imperforate outer portions, a continuous annular rim means encircling said disks and spaced radially outward therefrom to be slid axially over said disks, said rim means having an axial length corresponding to the axial length of said wheel, a plurality of blades peripherally spaced about said rim means with their spans extending radially outward, each said blade extending through said rim means and having radially extending slots therein receiving said imperforate outer portions of said disks thereinto, fused metal means at said slots fixing each said disk on both sides of the imperforate portion thereof to a said blade, and shaft means supporting said wheel for rotation about said axis, said disks comprising front and rear disks and intermediate disks bridging the gap between said front and rear disks and fixed thereto.

References Cited in the file of this patent UNITED STATES PATENTS 926,442 Smoot June 29, 1909 1,904,421 Doran Apr. 18, 1933 2,436,087 Benson Feb. 17, 1948 2,540,991 Price Feb. 6, 1951 2,604,298 Bachle July 22, 1952 2,649,243 Stalker Aug. 18, 1953 2,657,008 Atkinson Oct. 27, 1953 2,678,537 Stalker May 18, 1954 2,847,184 Islip Aug. 2, 1958 FOREIGN PATENTS 157,045 Australia June 15, 1954 492,801 Great Britain Sept. 17, 1938 518,874 Belgium Apr. 15, 1953 643,237 Great Britain Sept. 15, 1950 718,139 Great Britain Nov. 10, 1954 724,281 Great Britain Feb. 16, 1955 1,077,668 France Nov. 10, 1954 UNITED STATES PATENT OFFICE 1: CERTIFICATION OF CORRECTION Patent No.- 2,976,011 March 21,, l96l Edward A. Stalker It is hereby certified that error appears in the above numbered petent requiring correction and 'that the said Letters Patent should read'as corrected below.

Column 2, line 29, after "dies." insert the following: It will be noted that the disks 44 4L6 5 .1. and 56 are peripherally continuous and imperforate in their outer peripheries and over the area which receives the slotted ends of the blades in order to sustain the high centrifugal force encountered in a high speed rotor, Further the hlade'slots 5O 38, 52 are relatively narrow, of a width substantially the thickness of the disks so that bonding thereof takes place on both sides of the disk as indicated in the drawings.

Signed and sealed this 29th day of August 1961.

(SEAL) Attest:

ERNEST W. SWIDER v DAVID L.LADD

Attesting Officer I Commissioner of Patents

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