JP2015515576A - Trap balance weight and rotor assembly - Google Patents

Abstract

The balance weight (60, 160, 260) for the turbine rotor extends laterally from the block-shaped central body (62, 162, 262) and the opposite side of the central body (62, 162, 262). A pair of elastic spring arms (64, 164, 264) to emerge, wherein the central body (62, 162, 262) and the elastic spring arms (64, 164, 264) jointly define an arcuate shape. Elastic spring arms (64, 164, 264), at least one positioning structure (68, 268) extending from the radial outer surface of the balance weight (60, 160, 260), and each of the elastic spring arms A restriction tab (271) extending radially inward from the distal end of (64, 164, 264). [Selection] Figure 6

Description

  The present invention relates generally to rotating machinery, and more particularly to an apparatus for balancing a rotor.

  Gas turbine engines typically include a plurality of rotor stages, each having a row of airfoils, i.e., rotor disks carrying compressors or turbine blades. Turbine rotors are balanced to avoid damage and excessive loads on bearings and support structures, and loss of efficiency caused by loss of clearance between airfoil and surrounding structures (eg, caused by rubbing the shroud) It is necessary to let

  Despite efforts to balance its constituent elements first, the turbine rotor still needs to dynamically balance the following assembly. To this end, it is desirable to utilize balance weights that allow the mass of the rotor to be redistributed as needed, allowing the system imbalance to be fine-tuned to meet precise requirements. A separable balance weight is a common technique in large gas turbine engines. These include bolts, washers, nuts and other fasteners of various sizes.

  In some gas turbine rotors, especially in small engines, a single bolt or a group of bolts (referred to as “tie rods” or “tie bolts”) is used for CURVIC joints and friction over the length of the assembly. The joint is assembled. The tie bolt configuration is less weight than conventional bolted joints, but the absence of bolt holes eliminates the conventional mechanism on the rotor disk that can be used to mount an otherwise separable balance weight. . Thus, the current situation in the field of small turbine engines is to balance the assembly by selectively machining sacrificial surfaces on rotating parts. The material is removed at the largest imbalance to redistribute the rotor mass around the axis of rotation. This process is irreversible and can damage components such as an integral blade rotor or “blisk”, both of which are safety critical consequences and expensive.

US Patent Application Publication No. 2010/316696

  These and other shortcomings of the prior art are addressed by the present invention, which provides a trapped spring balance weight for a turbine rotor.

  According to one aspect of the present invention, a balance weight for a turbine rotor comprises a block-shaped central body and a set of elastic spring arms extending laterally from opposing sides of the central body, the central body And an elastic spring arm jointly defining an arcuate shape, at least one positioning structure extending from a radial outer surface of the balance weight, and radially inward from the distal end of each of the elastic spring arms And a restriction tab that extends to

  In accordance with another aspect of the present invention, a turbine rotor assembly includes a rotor element that includes an annular hub surface, an annular flange that surrounds the hub surface and is spaced from the hub surface to define a pocket; At least one balance weight disposed on the block, the balance weight being a block-shaped central body and a pair of elastic spring arms extending laterally from opposite sides of the central body, An elastic spring arm in which the central body and the elastic spring arm jointly define an arcuate shape, at least one positioning structure extending from a radial outer surface of the balance weight, and radial from the distal end of each of the elastic spring arms A restricting tab extending inwardly, and the elastic spring arm and the central body are elastically supported on the flange and the hub surface, respectively. To hold the balance weight. The radial height of the limiting tab is selected to prevent insertion of the balance weight into the pocket when the resilient spring arm is bent beyond a predetermined limit.

  The invention can be best understood by referring to the following description in conjunction with the accompanying drawings.

1 is a cross-sectional view of a gas turbine engine constructed in accordance with an aspect of the present invention. It is an enlarged view of the front part of the compressor of the engine shown in FIG. It is an enlarged view of the tail part of the compressor of the engine shown in FIG. It is a perspective view of the balance weight constructed | assembled by one aspect | mode of this invention. FIG. 5 is a rear elevation view of the balance weight of FIG. 4. FIG. 5 is a perspective view of the balance weight of FIG. 4 installed in the rotor disk of the engine of FIG. 1. FIG. 6 is a front view of a spanner tool for use with a balance weight. It is a side view of the spanner tool of FIG. It is a rear view of the spanner tool of FIG. FIG. 8 is a view of the spanner tool of FIG. 7 in use. It is a perspective view of the balance weight constructed | assembled by another aspect of this invention. FIG. 12 is a rear elevation view of the balance weight of FIG. 11. FIG. 12 is a perspective view of the balance weight of FIG. 11 installed in the engine of FIG. 1. It is sectional drawing of a part of compressor of the gas turbine engine in which the balance weight was installed. It is a perspective view of the balance weight of FIG. FIG. 16 is a rear elevation view of the balance weight of FIG. 15. It is a perspective view of the balance weight of FIG. 15 in the installed state.

  Referring to the drawings, wherein like reference numerals refer to like elements throughout the various views, FIG. 1 depicts an example gas turbine engine 10 that includes a compressor 12, a combustor 14, and a high pressure. Or it has a gas generator turbine 16 and a working turbine 18, all of which are arranged in series flow. The compressor 12, combustor 14 and gas generator turbine 16 are collectively referred to as the “core”. The compressor 12 provides compressed air that passes to the combustor 14 where fuel is injected and burned to produce hot combustion gases. The hot combustion gases are discharged into the gas generator turbine 16 where they are expanded and extract energy therefrom. The gas generator turbine 16 drives the compressor 12 via the main shaft 20. Pressurized air exiting the gas generator turbine 16 is discharged to the working turbine 18 where it is further expanded to extract energy. The working turbine 18 drives the internal shaft 22.

  In the illustrated example, the engine is a turboshaft engine and the internal shaft 22 will be coupled to an external load, such as a reduction gear case or propeller. However, the principles described herein are equally applicable to turboprop, turbojet and turbofan engines, and turbine engines used in other vehicles or stationary applications. These principles are also applicable to any other type of rotating machine (eg, wheel, gear, shaft, etc.) that requires balancing.

  In the illustrated example, the compressor 12 includes five axial rotor stages and a mixed flow stage positioned immediately upstream of the combustor 14. As best seen in FIG. 2, the first stage rotor 24 of the compressor 12 is an integrally bladed rotor or “blisk”, in this case a rotor disk 26 and a plurality of airfoil-shaped compressions. The instrument blade 28 is formed as one integral component. The tail end of the rotor disk 26 includes an annular hub surface 30 and an annular flange 32 extending across the hub surface 30. Hub surface 30 and flange 32 cooperate to define pocket 34 (best seen in FIG. 6). The inner surface 36 of the flange 32 has a row of grooves 38 formed therein (also see FIG. 6).

  As seen in FIG. 3, the final stage of the compressor 12 includes a rotor disk 40 that carries a plurality of blades 42. An annular main shaft 20 extends from the rotor disk 40 to the axial tail. The intermediate section of the main shaft 20 includes an annular hub surface 46 and an annular flange 48 extending across the hub surface 46. Hub surface 46 and flange 48 cooperate to define pocket 50 (best seen in FIG. 13). The flange 48 includes an annular row of apertures formed therein. In the illustrative example, as seen in FIG. 13, this row comprises open end slots 52 that alternate with holes 54.

  One or more forward balance weights 60 are installed in the pockets 34 of the first stage rotor 24, and one or more tail balance weights 160 are installed in the pockets 50 of the main shaft 20. The exact number, position and distribution of weights will vary from individual engine to individual engine. In the particular engine shown, only two balance weights are used. Correction of the rotor imbalance is accomplished by repositioning the weights as needed.

  4 and 5 illustrate one of the front balance weights 60 in more detail. It is generally arcuate in shape and comprises a block-like central body 62 from which elastic spring arms 64 extend laterally outward. A notch 66 is formed at the radially inner end of the central body 62. At the distal end of each resilient spring arm 64, an axially elongated rail 68 extends radially outward. A stop block 70 extends radially inward facing each rail 68. The front balance weight 60 may be constructed from any material having an appropriate density and the ability to form an elastic spring arm that can bend elastically. For example, a metal alloy can be used.

  Referring to FIG. 6, the front balance weight 60 is installed in the first stage rotor 24 as follows. The elastic spring arm 64 is bent radially inward with respect to the central body 62. They can be held in this position by a suitable tool or jig. The front balance weight 60 is then slid axially to enter the pocket 34 at the appropriate position. The elastic spring arm 64 is then released. After being released, the elastic spring force pushes the elastic spring arm 64 radially outward to hit the flange 32 and pushes the central body 62 to hit the hub surface 30. The rail 68 engages with the groove 38 on the inner surface of the flange 32 to prevent movement in the tangential direction. The component to be coupled (in this case, the front end of the annular shaft 72 seen in FIG. 2) abuts the notch 66 to prevent the forward balance weight 60 from moving in the axial direction. FIG. 6 shows one of the front balance weights 60 in the installed state. When the engine is operated, the load due to the centrifugal force is seated again so that the front balance weight 60 hits the flange 32.

  If necessary, the front balance weight 60 can be repositioned circumferentially while the compressor 12 is assembled, for example, by utilizing a spanner wrench tool, as shown by the balancing action. For example, FIGS. 7-9 illustrate a suitable tool 74 comprising an elongated handle 76 and a spanner finger 80 extending radially inward and laterally outward from its distal end. And a curved head 78. As shown in FIG. 10, a tool 74 is inserted into the pocket 34 and is used to bend the resilient spring arm 64 radially inward and disengage the rail 68 from the groove 38. The tool 74 is then moved tangentially in the direction of the arrow, bringing the spanner finger 80 into contact with the front balance weight 60 and pushing it into a new position. Once the tool 74 is removed, the rail 68 reengages the groove 38 at the new position. During such action, the stop block 70 contacts the annular shaft 72 if an attempt is made to bend the elastic spring arm 64 extremely. This avoids permanent deformation of the elastic spring arm 64.

  11 and 12 illustrate one of the tail balance weights 160 in detail. It is generally arcuate in shape and comprises a block-shaped central body 162 from which elastic spring arms 164 extend laterally outwardly. An anti-rotation knob 166 extends radially outward from the central body 162. A shear pin 168 extends radially outward at the distal end of each resilient spring arm 164. Opposing each shear pin 168, a stop block 170 extends radially inward. The front surface 172 of the tail balance weight 160 has a convex contour that is complementary to the cross-sectional shape of the pocket 50 in the main shaft 20. The tail balance weight 160 may be constructed from any material having a suitable density and the ability to form an elastic spring arm that can bend elastically. For example, a metal alloy can be used.

  As seen in FIG. 13, the tail balance weight 160 is installed using a method similar to that for the front balance weight 60 as follows. The resilient spring arm 164 is bent radially inward with respect to the central body 162 as indicated by the arrow in FIG. They can be held in this position by a suitable tool or jig. The tail balance weight 160 is then slid axially to enter the pocket 50 at the appropriate position. Stop block 170 is sized and shaped to prevent insertion into pocket 50 when elastic spring arm 164 is excessively bent, thereby avoiding permanent deformation of elastic spring arm 164. To do. The elastic spring arm 164 is then released. After being released, the elastic spring force pushes the elastic spring arm 164 radially outward to hit the flange 48 and pushes the central body 162 to hit the hub surface 46. An anti-rotation knob 166 engages one of the open end slots 52 in the flange 48. The shear pin 168 engages with the hole 54 in the flange 48 to prevent axial movement. FIG. 13 shows one of the tail balance weights 160 in the installed state. When the engine is operated, a load caused by centrifugal force causes the tail balance weight 160 to be seated again so as to hit the flange 48. If necessary, the tail balance weight 160 can be removed and repositioned while the compressor rotor is assembled without any unique jig or tool.

  Although the balance weights 60 and 160 are described as “front” and “tail” weights, it should be understood that these terms are merely used for convenience in describing certain embodiments. Depending on the specific engine and connecting hardware, either the turbine rotor disk or shaft front or tail design may be used. Furthermore, anti-rotation and axial restraining mechanisms can be modified or used in various combinations to form a balance weight suitable for a particular application.

  FIG. 14 illustrates a portion of the compressor section of a gas turbine engine, which is similar to the operating principle for the gas turbine engine 10 described above. The first stage rotor 224 in the compressor section is an integrally bladed rotor or “blisk”, where the rotor disk 226 and a plurality of airfoil-shaped compressor blades 228 are integrated components. It is formed. The tail end of the rotor disk 226 includes an annular hub surface 230 and an annular flange 232 extending across the hub surface 230. Hub surface 230 and flange 232 cooperate to define pocket 234 (best shown in FIG. 17). The inner surface 236 of the flange 232 has a row of grooves 238 formed therein (also shown in FIG. 17).

  One or more balance weights 260 are installed in the pockets 234 of the first stage rotor 224. The exact number, position and distribution of weights will vary from individual engine to individual engine. Correction of rotor imbalance is accomplished by repositioning the weights as needed.

  15 and 16 illustrate one of the balance weights 260 in more detail. It is generally arcuate in shape and comprises a block-like central body 262 from which a resilient spring arm 264 extends laterally outward. A notch 266 is formed at the radially inner end of the central body 262. At the distal end of each resilient spring arm 264, an axially elongated rail 268 extends radially outward. Opposite each rail 268, a stop block 270 extends radially inward. A limiting tab 271 extends radially inward from each stop block 270. The balance weight 260 may be constructed from any material having a suitable density and the ability to form an elastic spring arm that can bend elastically. For example, a metal alloy can be used.

  Referring to FIG. 17, the balance weight 260 is installed in the first stage rotor 224 as follows. The elastic spring arm 264 is bent radially inward with respect to the central body 262. They can be held in this position by a suitable tool or jig. The balance weight 260 is then slid axially to enter the pocket 234 at the appropriate position. The radial height “H” (see FIG. 15) of each restricting tab 271 relative to the stop block 270 is selected to prevent the resilient spring arm 264 from bending beyond a predetermined limit. More specifically, the height H is set so that the limiting tab 271 blocks the hub surface 230 until the elastic spring arm 264 can be bent sufficiently to cause its plastic deformation. After insertion, the elastic spring arm 264 is released. After being released, the remaining spring force pushes the resilient spring arm 264 radially outward to hit the flange 232 and pushes the central body 262 to hit the hub surface 230. The rail 268 engages with the groove 238 on the inner surface of the flange 232 to prevent tangential movement. The component to be coupled (in this case, the front end of the annular shaft 272 shown in FIG. 14) abuts the notch 266 to prevent the balance weight 260 from moving in the axial direction. FIG. 17 shows one of the balance weights 260 in the installed state. When the engine is operated, the load due to the centrifugal force is seated again so that the front balance weight 260 hits the flange 232. Balance weight 260 may be repositioned as described above with respect to balance weights 60 and 160. Note also that the limiting tab mechanism described with respect to balance weight 260 may be incorporated within balance weight 60 or 160.

  The balance weight design described herein has several advantages over the current state of the art for small engines. The process management is improved compared to the direct removal of material from the first stage rotor 24 which results in local stress concentration on critical rotating parts that are extremely stressed. Any stress concentration mechanism present on the balance weight 60, 160 or 260 is more optimally managed because it is formed using precision machining techniques. The cleanliness of the engine is also improved because the balance weight does not require any machining operations in the assembly of the engine and therefore does not generate dust and dust that can contaminate the engine system. Finally, the balancing stroke cycle time is reduced, which is related to the balancing stroke which allows the balancing weight to be easily repositioned while the rotor is loaded into the balancing weight machine, thereby removing material. This is because the rework loop can be eliminated.

  The above has described a balance weight for a turbine rotor and a balanced rotor assembly. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications can be made thereto without departing from the spirit and scope of the invention. Accordingly, the foregoing description of preferred embodiments of the invention and the optimal method for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation, and the invention is defined by the claims. ing.

DESCRIPTION OF SYMBOLS 10 Gas turbine engine 12 Compressor 14 Combustor 16 Gas generator turbine 18 Action turbine 20 Main shaft 22 Internal shaft 24, 224 First stage rotor 26, 40, 226 Rotor disk 28, 228 Compressor blade 30, 46, 230 Hub surface 32, 48, 232 Flange 34, 50, 234 Pocket 36, 236 Flange inner surface 38, 238 Groove 42 Blade 52 Open end slot 60 Front balance weight 160 Tail balance weight 260 Balance weight 62, 162, 262 Central body 64, 164 264 Elastic spring arm 66, 266 Notch 68, 268 Rail 70, 170, 270 Stop block 72, 272 Shaft 74 Tool 76 Handle 78 Head 80 Spanner finger 166 Anti-rotation knob 168 Shear pin 72 radial height of the forward face 271 limits Tab H limit tabs tail balance weight

Claims (13)

A block-shaped central body (62, 162, 262);
A pair of elastic spring arms (64, 164, 264) extending laterally from opposing sides of the central body (62, 162, 262), the central body (62, 162, 262) and An elastic spring arm (64, 164, 264) jointly defining an arcuate shape with said elastic spring arm (64, 164, 264);
At least one positioning structure (68, 268) extending from a radially outer surface of the balance weight (60, 160, 260);
A balance weight (60, 160, 260) for the turbine rotor comprising a restricting tab (271) extending radially inward from the distal end of each resilient spring arm (64, 164, 264).   The balance weight (60, 160, 260) according to claim 1, wherein an anti-rotation knob (166) extends radially outward from the central body (62, 162, 262).   The balance weight (60, 160, 260) of claim 1, wherein a shear pin (168) extends radially outward from a distal end of each of the resilient spring arms (64, 164, 264).   The balance weight (60,) of claim 1, wherein an axially elongated rail (68, 268) extends radially outward from a distal end of each of the resilient spring arms (64, 164, 264). 160, 260). A stop block (70, 170, 270) extends radially inward from the distal end of each of the resilient spring arms (64, 164, 264);
The balance weight (60, 160, 260) according to claim 1, wherein a limiting tab (271) extends radially inward from each of said stop blocks (70, 170, 270).   The balance weight (60, 160, 260) according to claim 1, wherein the central body (62, 162, 262) includes a notch (66, 266) formed at a radially inner end thereof. An annular hub surface (30, 46, 230) and a pocket (34, 50, 234) surrounding the hub surface (30, 46, 230) and being spaced apart from the hub surface (30, 46, 230) A rotor element (40, 226) including an annular flange (32, 48, 232) defining
At least one balance weight (60, 160, 260) disposed in the pocket (34, 50, 234), the balance weight (60, 160, 260) comprising:
A block-shaped central body (62, 162, 262);
A pair of elastic spring arms (64, 164, 264) extending laterally from opposing sides of the central body (62, 162, 262), the central body (62, 162, 262) and An elastic spring arm (64, 164, 264) in which the elastic spring arms (64, 164, 264) jointly define a bow shape;
At least one positioning structure (68, 268) extending from a radially outer surface of the balance weight (60, 160, 260);
A turbine rotor assembly comprising a restricting tab (271) extending radially inward from a distal end of each said resilient spring arm (64, 164, 264),
The elastic spring arm (64, 164, 264) and the central body (62, 162, 262) are elastic with respect to the flange (30, 46, 230) and the hub surface (30, 46, 230). The balance weights (60, 160, 260) are held in the pockets (34, 50, 234) by being respectively supported by the formula,
When the elastic spring arm (64, 164, 264) is bent beyond a predetermined limit when the radial height of the limiting tab (271) is bent, the balance weight (60, 160, 260) A turbine rotor assembly selected to prevent insertion into the pocket (34, 50, 234).   An anti-rotation knob (166) extends radially outward from the central body (62, 162, 262) and engages with an aperture in the flange (32, 48, 232), whereby the rotor disk ( The turbine rotor assembly according to claim 7, wherein axial movement of the balance weight (60, 160, 260) relative to 26, 40, 226) is prevented.   Each of the resilient spring arms (64, 164, 264) includes a shear pin (168) extending radially outward from its distal end, the shear pin (168) being in the flange (32, 48, 232). 8. The turbine rotor assembly of claim 7, wherein the balance weights (60, 160, 260) are prevented from axially moving relative to the turbine rotor by engaging an aperture in the bracket.   Each of the resilient spring arms (64, 164, 264) includes an axial elongate rail (68, 268) extending radially outward from its distal end, the rails (68, 268) comprising: The turbine rotor assembly of claim 7, wherein the turbine rotor assembly engages a groove in the flange (32, 48, 232).   Stop blocks (70, 170, 270) extend radially inward from the distal end of each of the resilient spring arms (64, 164, 264), and a restricting tab (271) extends to each stop block (70). , 170, 270) extending radially inward from the turbine rotor assembly of claim 7.   By further providing an auxiliary member (72, 272) that comes into contact with the pocket (34, 50, 234), the balance weight (60, 160, 260) is axially disposed in the pocket (34, 50, 234). The turbine rotor assembly of claim 7, wherein the turbine rotor assembly is held.   13. A turbine according to claim 12, wherein the central body (62, 162, 262) includes a notch (66, 266) formed at its radially inner end abutting the auxiliary member (72, 272). Rotor assembly.