US3032318A - Radial flow elastic fluid compressors or turbines - Google Patents

Description

y 1962 E. D. LINDBLOM 3,032,318

RADIAL FLOW ELASTIC FLUID COMPRESSORS OR TURBINEIS Filed June 1'7, 1957 United States Patent 3,032,318 RADIAL FLOW ELASTIC FLUID COMPRESSORS OR TURBINES Erik David Lindblom, Burevagen 35, Djursholm, Sweden Filed June 17, 1957, Ser. No. 665,896 Claims priority, application Sweden Aug. 11, 1956 7 Claims. (Cl. 253-95) The present invention relates to blade rings for radial flow elastic fluid compressors or turbines of the type having two or more blade supporting rings.

In machines of said type and more particularly those for high speed forces appear in the operation of the machines which exert a detrimental influence on the connection of the blades to their supporting rings and, in addition, tend to deform both the blades and the supporting rings. Particularly subjected to the said actions are the rings located at the greatest distance from the axis of the machine.

It is already known, in order to reduce such detrimentally acting forces, to provide the surfaces of the supporting rings remote from the blades with spaced projections for balancing such forces as are produced by the blades during their rotation. A drawback inherent in counter-weights of the above said kind is that the surface of generation of the supporting ring is rendered inconstant, giving rise to stress concentrations between the projections with resulting risk of breakage. It is further to be noted that in respect of such rings where the blade in accordance with well known practice is fastened to the supporting ring at one end surface thereof, the torque and the supporting pressure will be taken up by said end surface, causing the canting of the ring to increase the load of torque on the blade. In the said balancing of the supporting ring a torque had to be transferred to the blade by way of the attachment between the supporting ring and the blade.

The invention has for its object to provide a blade ring where the drawbacks above stated are eliminated.

According to a feature of the invention each blade is formed with an overhanging portion at one or both ends to act as a balancing Weight or weights in order both to reduce the load of torque on the blade and to eliminate the transfer of bending moments from the supporting ring to the blade.

This and other features of the invention will appear from the following description with reference to the accompanying drawing.

In the drawing, FIGS. 1, 2 and 3 show axial sections of three examples of blade rings embodying the invention.

FIG. 4 is a perspective view of a portion of a blade ring and its supporting device.

FIG. 5 is a perspective view of said supporting device free from the blade ring.

FIG. 6 is a detail view.

With reference to FIG. 1, the numeral 1 designates a blade and 2 and 3 are the associated supporting rings. The blades are formed with roots 4 and 5 having grooves 6 for receiving the supporting rings. The blanks for the blades are preferably cut from long pieces having the outline of the blade root desired, whereupon the grooves 6 are formed on a lathe while the blade blanks are held by a clamping device. After that the operating portions of the blades are worked by milling and grinding operations. The finished blades are inserted one by one into between the supporting rings, and finally at most one blade division is equalized by spreading the blades circumferentially, if necessary, in combination with insertion of thin profiled pieces uniformly distributed around the circumference. As an alternative, in case of blades having shallow grooves I apply the supporting rings by a shrinking operation,

Patented May 1, 1962 "ice while the blades are held like a ring in a clamping device.

The blade is self-balancing due to the provision of an overhanging portion 7 at each end. It is thus evident that the roots of the blade including said overhanging portions act both as means for connecting the blade to the supporting rings and as counter-weights.

The blade ring as a whole is connected to a running wheel, as a turbine disc 8, by means permitting a radial movement.

In order to keep the blades in engagement with the supporting rings when the blade ring is at rest, one lateral edge of each supporting ring is shown as formed with a projecting offset 9, the respective side walls of the grooves of the blade roots being correspondingly shaped and locked to said offsets by a pressing action. In operation, the side walls of the grooved blade roots will embrace the supporting rings with a firm grip.

FIG. 6 illustrates by Way of example a modified locking device. Formed in coengaging side surfaces of a supporting ring, as 3, and the groove 6 of a blade root, as 5, are grooves 16 and 17 in register with each other. Placed in the annular space resulting is an annular locking member 18 comprising an undivided of divided resilient V-. shaped sheet metal band or the like, originally insertedinto groove 16 which yields while the blade is being.

mounted to then again expand so as also to engage groove 17, thereby securing a reliable locking grip.

FIGS. 2 and 3 show parts of so called drum rings, that is to say, blade rings having more than one passage for the driving fluid, two such passages being indicated at a: and m, respectively. Passage a may be a central passage, to either sides of which there may be a passage as m.

The number of passages may be whichever desired.

In FIG. 2 the blade 5 is provided with an overhanging portion 7 similar to that of FIG. 1.

In FIG. 3 an overhanging portion of such a nature is indicated as to form an additional passage for the driving fluid, as indicated at n. In this embodiment the dimensions of passages as a, m and n, and of the overhanging portions should be so related to each other as to eliminate any detrimental influence of the lateral passages, as m, and the overhanging portions, as n, on the middle passage,

as a.

Let it be assumed, for instance, that passages and overhanging elements are of the same Weight of blade per unit of length, and a, m and n are assumed to indicate axial lengths, the said elimination of detrimental influence will be obtained provided the relation between passage and overhanging elements may be expressed by the formula and a rotary disc 8 of the machine, such as a turbine disc,

includes a ring 10 carried by said disc which is connected by pins 11 to a supporting ring, as 3, of the blade ring.

In FIGS. 4 and 5 a connecting ring 10 is shown which is provided at its edge facing the blade ring with a radially inwardly projecting annular flange 13 engaging a groove 14 formed in overhanging elements which is such a depth as not to prevent radial expansion of said flange and said element with relation to each other. For centering purposes as well as for the transfer of tangential forces the annular flange 13 may be provided with catch members, such as for instance, axially projecting studs 15 engaging corresponding grooves formed in or between overhanging elements.

It is to be noted that modifications may be made in respect of details Without departing from the principle of the invention or the scope of the appended claims. Thus, for instance, the blades provided in the overhanging portions may be designed either as turbine blades (for outward flow) or as compressor blades (for inward flow) with a view to counteracting leakage of driving fluid around the free end of the blade ring.

I claim:

1. In a blade ring for radial flow elastic fluid machines including axially extending blades and, at least two bladesupporting rings operatively engaging and supporting said blades at locations spaced apart axially whereby portions of said blades extend between said rings, a rotatable disc fixed to one of said supporting rings on the side thereof opposite the portions of said blades extending between said rings, and axially spaced from said blades, the characteristic feature that each blade is provided at least at its end facing said rotatable disc with an extension projecting axially outwardly beyond the respective supporting ring so as to form an axially overhanging member located radially inwardly of said supporting ring so that on rotation of the blade ring the centrifugal forces acting on opposite sides of said supporting ring may balance one another.

2. A blade ring as claimed in claim 1, and in which said overhanging members are, at a portion between their ends,profiled as blades so as to form passages for the elastic fluid between them.

3. A blade ring as claimed in claim 2, and in which said overhanging members each include a portion shaped to act as aturbine blade for outward flow.

4. A blade ring as claimed in claim 2, and in which said further feature that the overhanging members each include .a portion shaped to act as a compressor blade for inward flow.

5. A blade ring as claimed in claim 1, and in which the overhanging members of the blades are formed with grooves, a connecting ring fixing said rotatable disc to one of said supporting rings, said connecting ring having at its end facing the blade ring to which it is fixed a radially inwardly directed annular flange for engaging said grooves of the overhanging members, the relation dirnensions of said flange and said grooves being such as to allow the blade ring and the connecting ring to move freely radially with relation to each other.

6. A blade ring as claimed in claim 5, and in which said annular flange is provided with catch members and the overhanging members are formed with recesses receiving said .catch members.

7. In a blade ring for radial flow elastic fluid machines including axially extending blades and, at least two bladesupporting rings operatively engaging and supporting said blades at locations spaced apart axially whereby portions of said blades extend between said rings, a rotatable disc fixed to one of said supporting rings on the side thereof opposite the portions of said blades extending between said rings, and axially spaced from said blades, the characteristic feature that each blade is provided at least at its end facing said rotatable disc with a root member having a radially outwardly opening groove to receive the respective supporting ring and formed with an extension projecting axially outwardly beyond the supporting ring so as to' form an overhanging member located inwardly of the supporting ring, so that on rotation of the blade ring the centrifugal force acting on opposite sides of the supporting ring may balance one another.

References Cited in the file of thispatent UNITED STATES PATENTS 911,663 Ljungstrom Feb. 9, 1909 968,862 Ljungstromw...v Aug. 30, 1910 2,382,705 Gente Aug. 14, 1945 FOREIGN PATENTS 290,656 Great Britain Nov. 1, 1928 381,442 Great Britain Oct. 6, 1932 407,651 Italy Nov. 10, 1944 594,204 Great Britain Nov. 5, 1947

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