Hybrid construction of a turbomachine rotor

Abstract

A hybrid rotor for a turbomachine includes a rotor body including a first bearing surface and an intermediate seal region formed as one unitary component. A first rotating element formed as part of the rotor body operates to one of compress a fluid in response to a torque applied to the rotor body and expand a fluid to apply a first torque to the rotor body, the first rotating element being inseparable from the rotor body. A second rotating element formed as part of the rotor body operates to one of compress the fluid in response to the torque applied to the rotor body and expand the fluid to apply a second torque to the rotor body, the second rotating element being inseparable from the rotor body. A disk engagement portion is formed as part of the rotor body. A stub shaft includes a disk connection portion positioned proximate the rotor body, a tie bolt connection portion positioned distal from the rotor body, and a second bearing surface that cooperates with the first bearing surface to define a rotational axis. N disk elements are arranged sequentially along the rotational axis. Each disk element of the N disk elements is formed separately from the rotor body and includes an inboard engagement portion and an outboard engagement portion. The inboard engagement portion engages one of the disk engagement portion and the outboard engagement portion of an adjacent disk element of the N disk elements and the outboard engagement portion of each disk element engages one of the inboard engagement portion of an adjacent disk element of the N disk elements and the disk connection portion to inhibit relative rotation therebetween. Each disk element also includes a fluid interacting member operable in response to rotation about the rotational axis to one of compress the fluid and expand the fluid to apply a disk member torque to the rotor body. A tie bolt includes a first end attached to the rotor body and a second end that extends axially beyond the tie bolt connection portion of the stub shaft, the tie bolt operable to axially connect and compress the stub shaft, each of the N disk elements, and the rotor body.

Description

Docket No. 2024PF00736HYBRID CONSTRUCTION OF A TURBOMACHINE ROTORBACKGROUND

[0001] Industrial turbomachine rotors often include complex fluid interacting members including pump or compressor impellers, turbine impellers, blades, vanes, and the like. These fluid interacting members are selected to interact with a fluid that flows through the turbomachine to either compress, pressurize, pump, or extract energy to or from the fluid.

[0002] In some rotors, the fluid interacting members are able to be formed or machined as a unitary component with the remainder of the rotor. However, some rotors utilize more complex fluid interacting members that cannot be efficiently machined as part of the rotor.SUMMARY

[0003] In one aspect, a hybrid rotor for a turbomachine includes a rotor body including a first bearing surface and an intermediate seal region formed as one unitary component. A first rotating element formed as part of the rotor body operates to one of compress a fluid in response to a torque applied to the rotor body and expand a fluid to apply a first torque to the rotor body, the first rotating element being inseparable from the rotor body. A second rotating element formed as part of the rotor body operates to one of compress the fluid in response to the torque applied to the rotor body and expand the fluid to apply a second torque to the rotor body, the second rotating element being inseparable from the rotor body. A disk engagement portion is formed as part of the rotor body. A stub shaft includes a disk connection portion positioned proximate the rotor body, a tie bolt connection portion positioned distal from the rotor body, and a second bearing surface that cooperates with the first bearing surface to define a rotational axis. N disk elements are arranged sequentially along the rotational axis. Each disk element of the N disk elements is formed separately from the rotor body and includes an inboard engagement portion and an outboard engagement portion. The inboard engagement portion engages one of the disk engagement portion and the outboard engagement portion of an adjacent disk element of the N disk elements and the outboard engagement portion of each diskDocket No. 2024PF00736 element engages one of the inboard engagement portion of an adjacent disk element of the N disk elements and the disk connection portion to inhibit relative rotation therebetween. Each disk element also includes a fluid interacting member operable in response to rotation about the rotational axis to one of compress the fluid and expand the fluid to apply a disk member torque to the rotor body. A tie bolt includes a first end attached to the rotor body and a second end that extends axially beyond the tie bolt connection portion of the stub shaft, the tie bolt operable to axially connect and compress the stub shaft, each of the N disk elements, and the rotor body.

[0004] The hybrid rotor may also include N disk elements having a first disk element with an inboard engagement portion that is directly connected to the disk engagement portion, a second disk element having an inboard engagement portion directly connected to an outboard engagement portion of the first disk element, and a third disk element having an inboard engagement portion directly connected to an outboard engagement portion of the second disk element and an outboard engagement portion directly connected to the disk connection portion of the stub shaft.

[0005] The hybrid rotor may also include inboard engagement portions and outboard engagement portions of the N disk elements each having a plurality of teeth arranged circumferentially around the rotational axis to partially define a Hirth coupling.

[0006] The hybrid rotor may also include a first rotating element and a second rotating element having semi-enclosed centrifugal impellers.

[0007] The hybrid rotor may also include a first rotating element and a second rotating element each including centrifugal compressor impellers.

[0008] The hybrid rotor may also include a fluid interacting member of each of the N disk elements having a semi-enclosed centrifugal impeller.

[0009] The hybrid rotor may also include a fluid interacting member of each of the N disk elements having a centrifugal compressor impeller.

[0010] The hybrid rotor may also include a tie bolt having a tie bolt nut, and where the first end of the tie bolt threadably engages the rotor body and the tie bolt nut threadably engages theDocket No. 2024PF00736 second end of the tie bolt and engages the tie bolt connection portion of the stub shaft such that the tie bolt operates to fixedly attach and compress the stub shaft against the N disk elements and the N disk elements against the rotor body.

[0011] The hybrid rotor may also include an intermediate seal region formed as part of the rotor body and positioned with the first rotating element and the second rotating element on a first axial side and the N disk elements on a second axial side opposite the first axial side. Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0013] FIG. l is a longitudinal view of a hybrid turbine rotor.

[0014] FIG. 2 is a cross-section of the hybrid rotor of FIG. 3 taken in a plane that passes through the longitudinal axis.

[0015] FIG. 3 is an enlarged view of a portion of the rotor of FIG. 1 illustrating the disks and the tie bolt in an assembly condition.DETAILED DESCRIPTION

[0016] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.Docket No. 2024PF00736

[0017] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0018] It should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well (i.e., one or more), unless the context clearly indicates otherwise. Further, the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and / or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments, absent a specific statement to the contrary.

[0019] Also, terms such as “first”, “second”, “third” and so forth may be used herein to refer to various elements, information, functions, or acts, but should not be considered as limiting in any way. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly,Docket No. 2024PF00736 a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0020] In addition, the term “adjacent to” may mean that an element is relatively near to but not in contact with a further element or that the element is in contact with the further portion unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0021] FIG. 1 illustrates a hybrid rotor 100 that includes a rotor body 102 and a stub shaft 126 attached to the rotor body 102 and suitable for use in a number of different turbomachines. For example, the hybrid rotor 100 could be used as a turbine rotor or a compressor rotor as will be discussed in greater detail. Of course, other uses of the hybrid rotor 100 beyond those explicitly described herein are possible.

[0022] The rotor body 102 and the stub shaft 126 include various surfaces such as a first bearing surface 110 formed as part of the rotor body 102 and a second bearing surface 112 formed as part of the stub shaft 126 that each engage a bearing that in turn supports the rotor body 102 and the stub shaft 126 for rotation about a rotational axis 108. Other surfaces may be provided for sealing, engagement with a thrust bearing, and other purposes commonly needed with the particular type of machine that is using the hybrid rotor 100.

[0023] A first rotating element 104 and a second rotating element 106 are formed as part of the rotor body 102 with additional rotating elements formed as part of the rotor body 102 being possible. In the illustrated construction, four rotating elements formed as part of the rotor body 102 are illustrated. In some constructions, the rotor body 102, including the first rotating element 104, the second rotating element 106, and any additional rotating elements is a forged or cast component that is then finish machined to complete the necessary, seal surfaces, bearing surfaces, other surfaces, and rotating elements.

[0024] In the illustrated construction, the first rotating element 104, the second rotating element 106, and the additional rotating elements formed as part of the rotor body 102 eachDocket No. 2024PF00736 include an impeller 122 and specifically, a semi-closed centrifugal impeller 122. In compressors (e.g., centrifugal compressors), the impellers 122 operate to compress a fluid as it passes through each impeller 122 in response to a torque being applied to the hybrid rotor 100. In turbines, the impellers 122 convert energy within the flow of fluid as it passes through each impeller 122 to apply a torque to the hybrid rotor 100.

[0025] Other constructions may include different types of impellers 122 such as closed or open centrifugal impellers 122 or may replace the impellers 122 with other rotating elements such as blades or vanes.

[0026] In addition to the integrated rotating elements, the hybrid rotor 100 also includes a first disk element 116 and a Nth disk element 118, with additional disk elements being possible depending on the application of the hybrid rotor 100. Each of the first disk element 116 through the Nth disk element 118 are formed separately from the rotor body 102 and the stub shaft 126 and are then removably attached to the rotor body 102 and the stub shaft 126 as part of the assembly of the hybrid rotor 100. In the illustrated construction, and as will be described in greater detail with regard to FIG. 3 each of the first disk element 116 through the Nth disk element 118 are stacked and attached to the adjacent components via a joint, and in the illustrated construction, a Hirth joint of a Hirth coupling 128. “Hirth couplings,” also known as Hirth joints, are a type of mechanical coupling used to connect and precisely position shafts, wheels, disks, and cranks in various engineering applications. They are characterized by their unique design, which features radial grooves or teeth milled into the end faces of the components being joined. This design allows for a compact, self-centering connection with high torque capacity and minimal backlash.

[0027] It should be noted that while Hirth joints are illustrated herein, other arrangements may employ other types of joints or may inhibit relative rotation between the first disk element 116 through the Nth disk element 118 in another manner including other types of joints, mechanical attachment means, permanent attachment means (e.g., welding) and the like. The actual type of joint employed is not critical and is selected based on the particular application.

[0028] Each disk element of the illustrated construction includes an impeller that is formed as part of the disk element or attached to the disk element. In the illustrated construction, the first disk element 116 through the Nth disk element 118 each includes a closed impeller 124 withDocket No. 2024PF00736 other arrangements of the impeller being possible. As with the rotating elements, in compressors, the closed impellers 124 operate to compress a fluid as it passes through each closed impeller 124 in response to a torque being applied to the hybrid rotor 100. In turbines, the closed impellers 124 convert energy within the flow of fluid as it passes through each closed impeller 124 to apply a torque to the hybrid rotor 100.

[0029] Due to the complexities involved in manufacturing a closed impeller 124, it is advantageous to form such closed impellers 124 on separate disk elements rather than attempt to form them as part of the rotor body 102. Of course, other impeller arrangements or even different components entirely (e.g., blades or vanes) could be used in place of or in conjunction with the closed impellers 124.

[0030] FIG. 2 is a cross-sectional view of the hybrid rotor 100 of FIG. 1 which better illustrates the arrangement between the rotor body 102, the first disk element 116 through the Nth disk element 118, and the stub shaft 126.

[0031] In the illustrated construction, the first disk element 116 abuts the rotor body 102 to define a first joint therebetween, a second disk element abuts the first disk element 116 and forms a second joint therebetween, the Nth disk element 118 abuts the second disk element to form a third joint therebetween and the stub shaft 126 abuts the Nth disk element 118 to form a fourth joint therebetween. Thus, the rotor body 102, the first disk element 116, the second (and any additional) disk elements, the Nth disk element 118, and the stub shaft 126 are stacked axially along the rotational axis 108 with joints that allow axial movement but inhibit relative rotational movement between the adjacent components.

[0032] A tie bolt 202 includes a first end that fixedly engages the rotor body 102 with the tie bolt 202 extending axially along the rotational axis 108 to a distance that extends beyond the various stacked components. In most arrangements, the tie bolt 202 threadably engages the rotor body 102. However, other arrangements, including more permanent arrangements for attaching the tie bolt 202 and the rotor body 102 are possible.

[0033] The tie bolt passes through a central bore formed in each of the stacked components such that a second end of the tie bolt 202 extends axially beyond the stub shaft 126 and is exposed. A nut 204 engages the second end of the tie bolt 202 to axially fix the stacked components against one another and complete the assembly of the hybrid rotor 100. SufficientDocket No. 2024PF00736 tension is applied to the tie bolt 202 via the nut to assure no axial or relative movement between the stacked components during operation.

[0034] FIG. 3 illustrates a portion of the hybrid rotor 100 illustrated in FIG. 1 in an assembled state. FIG. 3 better illustrates the second joint 304 formed between the first disk element 116 and the second disk element 302 and the third joint 306 formed between the second disk element 302 and the Nth disk element 118 with other joints being similar. Each of the first disk element 116, the second disk element 302, and the Nth disk element 118 includes a plurality of axially extending teeth that engage or mesh with the teeth of the adjacent component to form the joint.

[0035] While FIG. 3 illustrates triangular-shaped teeth, other shapes including square or curved shapes could be employed. Once the teeth of the second joint 304 are engaged, the second joint 304 inhibits relative rotation between the first disk element 116 and the second disk element 302 but still allows for relative axial movement. Similarly, once the teeth of the third joint 306 are engaged, the third joint 306 inhibits relative rotation between the second disk element 302 and the Nth disk element 118 but still allows for relative axial movement.

[0036] The tie bolt 202, in cooperation with the stub shaft 126 and the nut 204 maintains the axial position of the first disk element 116, the second disk element 302, the Nth disk element 118, and the stub shaft 126 to lock these components in place for operation.

[0037] To assemble the hybrid rotor 100, the tie bolt 202 is connected to the rotor body 102. The first disk element 116 is positioned with the tie bolt 202 passing through its central bore and with the first disk element 116 engaged with the rotor body 102 to define the first joint.The second disk element 302 is then positioned in a manner similar to the first with the teeth of the second disk element 302 engaging the teeth of the first disk element 116 to define the second joint 304. This process is repeated through the Nth disk element 118 which engages the adjacent disk element (the second disk element 302 as illustrated herein) to define the third joint 306. The stub shaft 126 is then positioned and engages the Nth disk element 118 to define a final joint therebetween. Once stacked, the nut 204 is coupled to the exposed portion of the tie bolt 202 to complete the assembly. It should be noted that the tie bolt 202 can be connected to the rotor body 102 before the stacking process, during the stacking process, or at some intermediate step therebetween.Docket No. 2024PF00736

[0038] Once the hybrid rotor 100 is assembled it can be installed in a casing to largely enclose the hybrid rotor 100 and specifically each of the disk elements and the rotating elements for operation. If the hybrid rotor 100 is being used in a compressor, a motor or other drive member is coupled to the hybrid rotor 100 to produce rotation at a desired speed. A fluid to be compressed is delivered to one or more of the rotating elements or disk elements in parallel or in series. For example, in one arrangement, the fluid enters the hybrid rotor 100 at the first rotating element 104. The first rotating element 104 and the associated stationary components (e.g., casings, seals, housings, diffusers, etc.) cooperate to compress the fluid and discharge the compressed fluid from the first rotating element 104. The compressed fluid is then directed to the second rotating element 106 which operates in a similar manner to further compress the fluid. This process repeats until the fluid passes through each of the rotating elements and is discharged from the Nth or last of the rotating elements. The fluid is then directed to the first disk element 116 which operates in a manner similar to that described with regard to the rotating elements to further compress the fluid. In the illustrated construction, the disk elements include closed impellers 124 that are more efficient at the higher pressure of the fluid. Again, this process is repeated for each disk element before the fully compressed fluid is discharged from the compressor.

[0039] It should be noted that the first rotating element 104 the second rotating element 106, and the first disk element 116 through the Nth disk element 118 are selected for convenience of illustration and do not represent an actual order of the elements or stages. Thus, any rotating element could be the first rotating element 104 and any disk element could be the first disk element 116.

[0040] The arrangements illustrated and described herein allow for a portion of the hybrid rotor 100 to be manufactured as a single component with another portion being stacked or attached. While forming the hybrid rotor 100 as a single unitary component provides a stable and strong component, the machining of the flow elements in each stage of the hybrid rotor 100 can be challenging. In some cases, such as when using closed impellers 124, the machining when formed as part of the rotor body 102 is too challenging and it is better to form the closed impellers 124 on separate disk elements. The arrangement illustrated herein thus allows for rotors that include both impellers 122 formed as part of the rotor body 102 and closed impellers 124 formed separately from the rotor body 102.Docket No. 2024PF00736

[0041] Increased power density of a turbomachine rotor can be accomplished by using integrally machined semi-open impellers with very high surface speed capability. Such semiopen impellers typically have lower efficiency than similar closed impellers. The use of separate disk elements that include closed impellers allows for these more complicated machining operations to take place separate from the rest of the rotor, and the closed impeller design allows for higher efficiencies than a similar application using semi-open impellers.

[0042] Compared to a design where all the impellers are formed as part of separate disks and attached to one another via a tie bolt arrangement, the hybrid solution can achieve similar performance in a smaller size. This reduces material cost, machining costs, and package costs. Additionally, the integrally machined impellers result in a cost savings over the same size rotor formed with all separate disk impellers.

[0043] To form the hybrid rotor 100 of FIG. 1, a rough rotor piece if first procured. The rough rotor piece is sized and arranged to allow for the machining of any integrally machined impellers as well as other rotor features (e.g., bearing surfaces). Each disk element is separately machined before being attached to the rotor body 102.

[0044] FIG. 1 and FIG. 2 show back-to-back configurations with semi-open, integrally machined impellers in one process section (one side of the intermediate seal region 118) and closed impellers supported on disk elements in the other process section with the intermediate seal region 118 operable to form a seal therebetween and define a portion of a balance piston located between the sections. A tie bolt is used to attach the disk elements to the rotor body 102. Of course, other arrangements such as straight through configurations and parallel arrangements are possible.

[0045] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0046] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope: the scope of patented subject matter is defined only by the allowedDocket No. 2024PF00736 claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

Docket No. 2024PF00736CLAIMSWhat is claimed is:

1. A hybrid rotor for a turbomachine, the hybrid rotor comprising: a rotor body including a first bearing surface and an intermediate seal region formed as one unitary component; a first rotating element formed as part of the rotor body and operable to one of compress a fluid in response to a torque applied to the rotor body and expand a fluid to apply a first torque to the rotor body, the first rotating element being inseparable from the rotor body; a second rotating element formed as part of the rotor body and operable to one of compress the fluid in response to the torque applied to the rotor body and expand the fluid to apply a second torque to the rotor body, the second rotating element being inseparable from the rotor body; a disk engagement portion formed as part of the rotor body; a stub shaft having a disk connection portion positioned proximate the rotor body, a tie bolt connection portion positioned distal from the rotor body, and a second bearing surface that cooperates with the first bearing surface to define a rotational axis;N disk elements arranged sequentially along the rotational axis, each disk element of the N disk elements formed separately from the rotor body and including: an inboard engagement portion; an outboard engagement portion, the inboard engagement portion engaged with one of the disk engagement portion and the outboard engagement portion of an adjacent disk element of the N disk elements and the outboard engagement portion of each disk element engaged with one of the inboard engagement portion of an adjacent disk element of the N disk elements and the disk connection portion to inhibit relative rotation therebetween; and a fluid interacting member operable in response to rotation about the rotational axis to one of compress the fluid and expand the fluid to apply a disk member torque to the rotor body; a tie bolt having a first end attached to the rotor body and a second end that extends axially beyond the tie bolt connection portion of the stub shaft, the tie bolt operable to axially connect and compress the stub shaft, each of the N disk elements, and the rotor body.Docket No. 2024PF007362. The hybrid rotor of claim 1, wherein the N disk elements includes a first disk element having an inboard engagement portion that is directly connected to the disk engagement portion, a second disk element having an inboard engagement portion directly connected to an outboard engagement portion of the first disk element, and a third disk element having an inboard engagement portion directly connected to an outboard engagement portion of the second disk element and an outboard engagement portion directly connected to the disk connection portion of the stub shaft.

3. The hybrid rotor of claim 1, wherein each of the inboard engagement portions and the outboard engagement portions of the N disk elements includes a plurality of teeth arranged circumferentially around the rotational axis to partially define a Hirth coupling.

4. The hybrid rotor of claim 1, wherein the first rotating element and the second rotating element include semi-enclosed centrifugal impellers.

5. The hybrid rotor of claim 1, wherein the first rotating element and the second rotating element include centrifugal compressor impellers.

6. The hybrid rotor of claim 1, wherein the fluid interacting member of each of the N disk elements includes a semi-enclosed centrifugal impeller.

7. The hybrid rotor of claim 1, wherein the fluid interacting member of each of the N disk elements includes a centrifugal compressor impeller.

8. The hybrid rotor of claim 1, wherein the tie bolt includes a tie bolt nut, and wherein the first end of the tie bolt threadably engages the rotor body and the tie bolt nut threadably engages the second end of the tie bolt and engages the tie bolt connection portion of the stub shaft such that the tie bolt operates to fixedly attach and compress the stub shaft against the N disk elements and the N disk elements against the rotor body.

9. The hybrid rotor of claim 1, further comprising an intermediate seal region formed as part of the rotor body and positioned with the first rotating element and the second rotating element on a first axial side and the N disk elements on a second axial side opposite the first axial side.

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