WO2015084467A2

WO2015084467A2 - Hydromotive machine impeller attachment

Info

Publication number: WO2015084467A2
Application number: PCT/US2014/056693
Authority: WO
Inventors: Henry K. Obermeyer
Original assignee: Obermeyer Henry K
Priority date: 2013-09-19
Filing date: 2014-09-19
Publication date: 2015-06-11
Also published as: WO2015084467A3; WO2015084467A8

Abstract

Hydromotive and aeromotive machines with impellers or the like secured by streamlined and sealed multi jackbolt assemblies are described. The disclosed assembly also provides for a tightening of the fit of the drive spline as the multi jackbolt assembly is preloaded.

Description

September 19, 2014 PCT Patent Application of Henry K. Obermeyer Hydromotive and Aeromotive Machine Impeller Attachment Field of the Invention

The present invention relates to the attachment of hydromotive and aeromotive machine impellers such as hydroturbine runners, pump impellers, aircraft propellers, fans, wind turbine rotor hubs, marine propulsion propellers and the like to their respective shafts. This invention is particularly advantageous with respect to attaining a high torque capacity in conjunction with a compact hub. By enabling the use of a compact hub, higher specific speeds, lower specific weights, and higher hydraulic efficiencies may be achieved.

Description of the Related Art Hydromotive machines, in particular hydroturbines, have incorporated a number of runner-to-shaft attachment methods. Spline connections provide high torque capacity in a small diameter. The spline connection itself transmits no thrust, however. Thrust must be transmitted by another element. A nut at the end of the shaft and adjacent to the spline may be used. This arrangement results in several shortcomings. For example, the nut may come loose with catastrophic results. Tightening of the nut tensions the splined shaft and axially compresses and radially expands the internal spline, thus undesirably loosening the fit of the spline. Applying high torque to a nut and shaft may be inconvenient because relative rotation of the shaft must be prevented during tightening. Multi jackbolt tensioners may be used to greatly reduce the shaft torque that results from tightening. Conventional multi jackbolt tensioners provide no corrosion protection for the bolt and do not provide a

hydrodynamically efficient surface in contact with the flowing medium.

Multi jackbolt fasteners are marketed under the registered trademark Super-Bolt®.

USPTO records indicate that as of September 19, 2013, the SUPERBOLT trademark was applied for on March 4, 2013 and assigned serial number 85865495. Trademark

Registration numbers to Steinbock Machinery Corporation include 73837362 filed Nov 9, 1989 and 73503930 filed October 15, 1984.

Prior art patents related to the present application include US4,846,614 to Steinbock; US RE 33490 to Stembock; US5,083,889; 6,199,453; 6,381,827; US 6,1 12,396 to Steinbock; US 6199453B1 to Stembock, US 6,263,764 to 8tembock,US 6381827 to Stembock, all herein incorporated by reference.

Summary of the Invention

According to this invention, a compact high capacity coupling between impeller and shaft is provided wherein the spline fit clearance is reduced or eliminated, rather than increased as a result of nut tightening. Additionally the nut serves to protect the mating bolt from corrosion, thus facilitating the use of (non-stainless) high strength alloy steel, for example, for the mating bolt. The female spline may incorporated into a flanged adaptor rather than be cut into the impeller hub, allowing the spline to be broached and while not requiring that the impeller itself be transported to and set up on a gear cutting machine. This also permits the OD of the small end of the hub to be smaller than the spline. In accordance with a further aspect of this invention, the nut is provided with a blind hole so as to exclude the fluid medium from the mating bolt and thereby protect it from corrosion.

In accordance with a further aspect of this invention, the nut is fitted with a flexible seal, such as an O-ring, for the purpose of excluding the fluid medium from the thread engagement area, thus reducing the potential for corrosion and the potential for sand or other debris to interfere with smooth engagement of the threaded connection.

In accordance with a further aspect of the invention, the multi jackbolt nut is contoured on its outer surface to minimize fluid friction and turbulence losses at the junction of the multi jackbolt and the impeller.

In accordance with a further aspect of the invention, the shaft is drilled beyond the location of the spline on the exterior of the shaft in order that the threads on the inside of the shaft are located beyond the splined portion of the shaft. In this manner, as the bolt is tightened, the shaft is axially pre-loaded in compression, causing it to swell radially in accordance with Poisson's ratio. The swelling results in a tighter fit of the spline during operation of the hydromotive machine while permitting the use of a slip fit that is convenient for assembly and also permitting the use of looser manufacturing tolerance on the splines.

In accordance with a further aspect of the invention, the multi jackbolt nut is shaped to act as a fairing or diffuser surface in conjunction with the impeller hub.

In accordance with a further aspect of the invention, a flexible seal such as an O-ring is provided to seal the interface between the splined flange and the impeller.

In accordance with a further aspect of the invention, stainless steel jack bolts may be used in conjunction with a bronze multi jackbolt nut.

It accordance with a further aspect of the invention, the pitch and hand of the bolt threads in the shaft and in the multi jackbolt nut may be the same so as to prevent the generation of a loosening torque on the bolt in response to axial loads thereon.

In accordance with a further aspect of the invention a washer used to spread loads from the jacking bolts may also incorporate sealing means to the impeller and to the multi jackbolt nut.

In accordance with a further aspect of the invention the sealing means between the multi jackbolt nut and the impeller may include a metallic spring. Such a spring may be used to compensate for stress relaxation of the elastomer which might otherwise compromise the effectiveness of an elastomeric seal. It is the nature of certain embodiments of the present invention that the gap to be sealed increases in size upon tightening of the assembly. Such an increase in the size of the gap to be sealed may be overcome by the use of a metallic spring.

In accordance with a further aspect of the invention, the multi jackbolts may engage wedges which in turn engage the impeller. In this manner the tapped holes for the multi jackbolts may be more efficiently oriented relative to the aerodynamically or

hydrodynamically constrained shape of the nut.

In accordance with a further aspect of the invention, a single jack bolt may be used to tighten a circumferential wedge element that tightens between the nut and the impeller.

In accordance with a further aspect of the invention, a seal may be established across a radial gap between the impeller and the multi jackbolt nut.

In accordance with a further aspect of this invention, a seal may be accomplished across a radial gap between a washer and the multi jackbolt nut. In accordance with a further aspect of the invention, a seal may be established across a radial gap between the impeller and the multi jackbolt nut.

In accordance with a further aspect of this invention, a seal may be accomplished across a radial gap between a washer and the impeller. It should be understood that the term multi jackbolt nut is to be interpreted to include alternative elements of similar function including the instance of the head of a bolt (instead of the body of a nut) being fitted with multiple jack bolts.

It should be understood that the term impeller is to interpreted broadly to include alternative elements of analogous function including hydroturbine runners, pump impellers, fan blades, propulsion propellers, traction propellers, mixers, grinders, augers, and the like as well as other rotating assemblies or devices for which corrosion protection of certain elements is desirable or in which a multi jack bolt nut conformed to a desired flow path is desirable.

It should be further understood that the term fluid is to be interpreted broadly to include liquids, slurries, gases, solids suspended in gas, powders, granules, seeds, grains, foodstuffs, molten metal, combinations of the above, and the like.

Brief Description of the Drawings

Figure 1 shows a prior art multi jackbolt tensioners.

Figure 2 shows the attachment of a water turbine runner to a shaft in accordance with the present invention.

Figure 3 is a sectional elevation drawing of an embodiment of the present invention. Figures 4 is a sectional elevation drawing of a further embodiment of the present invention.

Figures 5 is a sectional elevation drawing of a further embodiment of the present invention.

Figures 6a, 6b, and 6c depict a multi jackbolt arrrangment wherein the jackbolts engage wedges that in turn engage the impeller.

Figures 7a and 7b depict a nut tightening arrangement wherein a circumferential wedge that may be tightened by a single bolt is used to tighten a streamlined nut to an impeller hub.

Figure 8 is a sectional elevation of the attachment of a water turbine runner to its shaft in accordance with the present invention.

Figure 9 is an exploded view of the jack bolt nut subassembly of Figure 8.

Figure 10 illustrates the as-manufactured shape of the end of the sp lined shaft shown in

Figure 8.

Figure 11 illustrates the sp lined shaft of Figure 10 as it would deform in response to axial pre-load of the jack bolt assembly if not radially constrained by its mating spline.

Description of the Preferred Embodiments of the Invention

Referring to Figure 1, a prior art multi jackbolt tensioning devices are shown. Note that the exterior profiles are not designed to minimize fluid friction should they be used to retain the impeller of a hydromotive machine. Figure 2 shows a hydroturbine runner 6 attached to its shaft 5 in accordance with the present invention. Spline connection 15 between shaft 5 and runner flange 9 transmit torque between shaft 5 and runner flange 9. Contacting surface 14 is in compression in accordance with pre-load on bolt 4. Shaft portion 13 is thus in compression causing it to swell as a result of pre-load on bolt 4. The end 4b of bolt 4 may be shaped to fit the bottom of its hole in shaft 5 in order that bolt 5 may be positively seated and located prior to further assembly and without causing to bottom out on the mating threads of shaft 5. Runner flange 9 is secured to runner 6 with bolts 10 and is sealed to runner 6 with O-ring 8. O-rings 11 and 12 seal the runner flange to the shaft. The engaged splines 15 and bolt 4 are thus kept dry and protected from corrosion. Nut 1 engages the other end of bolt 4 and is tightened with multi jackbolts including 2 and 3. O-ring 7 forms a seal between nut 1 and runner 6.

Referring now to Figure 3, bolt 4 extends through runner 6 and engages nut 1. Nut 1 is tightened with multi jackbolts 2. Cover 21 covers multi jackbolts 2 and is sealed to nut 1 with O-ring 22. Nut 1 is in turn sealed to runner 6 with O-ring 18. Using this arrangement, bolt 4 and multi jackbolts 2 are protected from corrosion and need not be made from stainless steel or the like. Cover 21 may engage the same threads in nut 1 as are engaged by bolt 4.

Referring now to Figure 4, bolt 4 engages nut 1 that is tightened using multi jackbolts 2. Multi jackbolts 2 are sealed to nut 1 with O-rings 16 or equivalent means. Nut 1 is sealed to runner 6 by O-ring 18 which is situated in a radial gap not subject to loosening as nut 1 is tightened on bolt 4. Gap 19 illustrates the gap formed between nut 1 and runner 6 as bolt 4 is tightened. Hardened washer 17 may be provided so as to prevent multi jack bolts 2 from indenting runner 6. Referring now to Figure 5, nut 1 is sealed to multi jack bolts 2 by O-rings 16. Nut 1 is likewise sealed to runner hub 6 by O-ring 18. Bolt 4 is thus kept dry and protected from corrosion and infiltration of sand.

Referring now to Figures 6a, 6b, and 6c, nut 1 is tightened on bolt 4 against impeller hub 6 by tightening jacking screws 2 against wedges 23. This arrangement allows jacking screws 2 to be oriented more nearly normal to the fluid flow optimized surface of nut. In this case the jacking screws are inclined relative to the axis of rotation. The wedges may also be designed at such angle so as to provide additional mechanical advantage. Such an orientation of the jacking screws may allow larger jacking screws to be used than in the case of jacking screws parallel to the axis of rotation (of the shaft and impeller or the like). Furthermore, jacking screws more nearly normal to the direction of fluid flow may be precisely sized (as to length) so as minimize disturbance to the flow be the screw head and its associated recess. Referring now to Figures 7a and 7b, a nut arrangement is shown that provides for circumferential wedge element 24 to be tightened with screw 25 between nut 1 and impeller 24. Bolt 4 is sealed form the surroundings by O-ring 26. Referring to Figures 8, 9, 10 and 11, a hydroturbine runner 6 attached to its shaft 5 in accordance with the present invention is shown. Spline connection 15 between shaft 5 and runner 6 transmit torque between shaft 5 and runner 6. Contacting surface 14 is in compression in accordance with pre-load on bolt 4. Shaft portion 13 is thus in compression causing it to swell as a result of pre-load on bolt 4. The OD 29 of the as manufactured shaft 5 is illustrated in Figure 10. The OD 28 of the axially loaded shaft 5 is shown in Figure 11. The axial load on portion 13 of shaft 5 is a result of the tension in bolt 4 acting on shaft internal threads 4c which oppose compressive loads on contact face 14 (Figure 8) shown as load vectors 30 in Figure 11. The end 4b of bolt 4 may be shaped to fit the bottom of its hole in shaft 5 in order that bolt 5 may be positively seated and located prior to further assembly and without causing to bottom out on the mating threads of shaft 5. Runner 6 is sealed to stainless steel shaft sleeve 27 by O-rings 11 and 12. The engaged splines 15 and bolt 4 are thus kept dry and protected from corrosion, thus allowing shaft 5 and bolt 4 to be manufactured from high strength alloy steel rather than of stainless steel. Nut 1 engages the other end of bolt 4 and is tightened with multi jackbolts 3. O-ring 32 forms a seal between nut 1 and runner 6. O-ring 33 forms a seal between cover 21 and multi -jack bolt nut 1. Cover 21 is preferably attached by being threaded onto bolt 4. Referring to Figure 9, an exploded view of the jack bolt nut assembly of Figure 8 is shown. Cover 21 is threaded into position using machined recesses 21a. Cover 21 seals to nut 1 with O-ring 33. Jack bolts 3 thread into nut 1 and bear on hardened washer 17. O-ring 32 seals between jack bolt nut 1 and impeller or the like 6. Referring to Figure 10, a cut-away portion of shaft 5 is shown. 5c indicates a threaded hole for engagement of bolt 4 (of Figure 8) in conjunction with a clearance hole 5d which contains but does not engage bolt 4 (of Figure 8). The as-manufactured spline outside diameter (OD) 29 is shown.

Referring to Figure 11, the hypothetical shape of the shaft of Figure 10 is shown after it has been axially compressed during assembly. For illustration purposes, the spline is shown in the (relative to Figure 10) shape it would assume if not partially constrained by the mating impeller or the like, the outside diameter of the shaft having increased so as to provide a more precise and rigid fit than the fit upon initial (not yet pre-loaded) assembly.

As the foregoing description illustrates, the present invention provides a secure connection that is readily manufactured without the need for interference fits and which may be readily installed in the field with simple hand tools. The present invention extends the use of multi-jack bolts to rotating machinery connections which must be as small as possible and shaped to minimize obstruction to fluid flow while also protecting critical elements from corrosion and contamination by abrasive materials. The term "spline is used broadly to include involute splines, non-involute splines, polygons, and all non-cylindrical shaft surface shapes that, when engaged with a complementary shape on the mating impeller or the like, prevent unintended relative rotation between the shaft and its impeller or the like. The terms "jacking screws", "jackbolts" and "jack bolts" are used interchangeably herein.

As can be easily understood from the foregoing, the basic concepts of the present invention may be embodied in a variety of ways. It may, for example, water turbines, pump impellers, propellers, mixers, agitators, fans, aircraft propellers, turbine rotors or other devices to accomplish the appropriate method. In this application, the shaft-to- impeller-or-the-like attachment methods are disclosed as part of the results shown to be achieved by the various devices described and as steps which are inherent to utilization. They are simply the natural result of utilizing the devices as intended and described. In addition, while some devices are disclosed, it should be understood that these not only accomplish certain methods but also can be varied in a number of ways. Importantly, as to all of the foregoing, all of these facets should be understood to be encompassed by this disclosure. The discussion included in this application is intended to serve as a basic description. The reader should be aware that the specific discussion may not explicitly describe all embodiments possible; many alternatives are implicit. It also may not fully explain the generic nature of the invention and may not explicitly show how each feature or element can actually be representative of a broader function or of a great variety of alternative or equivalent elements. Again, these are implicitly included in this disclosure. Where the invention is described in device-oriented terminology, each element of the device implicitly performs a function. Apparatus claims may not only be included for the device described, but also method or process claims may be included to address the functions the invention and each element performs. Neither the description nor the terminology is intended to limit the scope of the claims which are included in this patent application.

It should also be understood that a variety of changes may be made without departing from the essence of the invention. Such changes are also implicitly included in the description. They still fall within the scope of this invention. A broad disclosure encompassing both the explicit embodiment(s) shown, the great variety of implicit alternative embodiments, and the broad methods or processes and the like are

encompassed by this disclosure and may be relied upon when drafting the claims for the full patent application.

This patent application seeks examination of as broad a base of claims as deemed within the applicant's right and is designed to yield a patent covering numerous aspects of the invention both independently and as an overall system.

Further, each of the various elements of the invention and claims may also be achieved in a variety of manners. This disclosure should be understood to encompass each such variation, be it a variation of an embodiment of any apparatus embodiment, a method or process embodiment, or even merely a variation of any element of these.

Particularly, it should be understood that as the disclosure relates to elements of the invention, the words for each element may be expressed by equivalent apparatus terms or method terms— even if only the function or result is the same. Such equivalent, broader, or even more generic terms should be considered to be encompassed in the description of each element or action. Such terms can be substituted where desired to make explicit the implicitly broad coverage to which this invention is entitled. As but one example, it should be understood that all actions may be expressed as a means for taking that action or as an element which causes that action. Similarly, each physical element disclosed should be understood to encompass a disclosure of the action which that physical element facilitates. Regarding this last aspect, as but one example, the disclosure of a "multi jack bolt" or a "bolt" should be understood to encompass disclosure of the act of "bolting"— whether explicitly discussed or not— and, conversely, were there effectively disclosure of the act of "bolting", such a disclosure should be understood to encompass disclosure of a "bolt" and even a "means for bolting". Such changes and alternative terms are to be understood to be explicitly included in the description. Patents, publications, or other references mentioned in this application for patent are hereby incorporated by reference. In addition, as to each term used it should be understood that unless its utilization in this application is inconsistent with such interpretation, both traditional and common dictionary definitions should be understood as incorporated for each term and all definitions, alternative terms, and synonyms such as contained in the Random House Webster's Unabridged Dictionary, second edition are hereby incorporated by reference. Finally, all references listed in the list of References To Be Incorporated By Reference In Accordance With The Provisional Patent Application or other information statement filed with the application are hereby appended and hereby incorporated by reference, however, as to each of the above, to the extent that such information or statements incorporated by reference might be considered inconsistent with the patenting of this/these invention(s) such statements are expressly

not to be considered as made by the applicant(s). Thus, the applicant(s) should be understood to claim at least: i) each of the water controlling devices as herein disclosed and described, ii) the related methods disclosed and described, iii) similar, equivalent, and even implicit variations of each of these devices and methods, iv) those alternative designs which accomplish each of the functions shown as are disclosed and described, v) those alternative designs and methods which accomplish each of the functions shown as are implicit to accomplish that which is disclosed and described, vi) each feature, component, and step shown as separate and independent inventions, vii) the applications enhanced by the various systems or components disclosed, viii) the resulting products produced by such systems or components, ix) methods and apparatuses substantially as described hereinbefore and with reference to any of the accompanying examples, x) the various combinations and permutations of each of the elements disclosed, xi) each potentially dependent claim or concept as a dependency on each and every one of the independent claims or concepts presented xii) individual or combined subroutines and programs as herein disclosed and described, xiii) the related methods disclosed and described, xiv) similar, equivalent, and even implicit

variations of each of these systems and methods, xv) those alternative designs which accomplish each of the functions shown as are disclosed and described, xvi) those alternative designs and methods which accomplish each of the functions shown as are implicit to accomplish that which is disclosed and described, xvii) each feature, component, and step shown as separate and independent inventions, and xviii) the various combinations and permutations of each of the above.

It should also be understood that for practical reasons and so as to avoid adding potentially hundreds of claims, the applicant may eventually present claims with initial dependencies only. Support should be understood to exist to the degree required under new matter laws— including but not limited to European Patent Convention Article 123(2) and United States Patent Law 35 USC 132 or other such laws— to permit the addition of any of the various dependencies or other elements presented under one independent claim or concept as dependencies or elements under any other independent claim or concept. Further, if or when used, the use of the transitional phrase "comprising" is and will be used to maintain the "open-end" claims herein, according to traditional claim interpretation. Thus, unless the context requires otherwise, it should be understood that the term "comprise" or variations such as "comprises" or "comprising", are intended to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of elements or steps. Such terms should be interpreted in their most expansive form so as to afford the applicant the broadest coverage legally permissible.

Claims

Claims: What is claimed is:

1. A multi jackbolt assembly used to secure an impeller or the like onto its shaft, further comprising a streamlined nut.

2. A multi jackbolt assembly used to secure an impeller or the like onto its shaft, further comprising a streamlined nut.

3. A multi jackbolt assembly used to secure an impeller or the like onto its shaft, further comprising a streamlined outer surface.

4. An assembly of a shaft and associated impeller or the like including a sp lined connection between the shaft and its impeller or the like and an coaxial bolt securing the impeller or like to said shaft, wherein said coaxial bolt engages the shaft inboard of the spline, and wherein said coaxial bolt does not engage the shaft over at least half of the length of the spline.

5. The assembly of Claim 4, further comprising a multi-jack bolt assembly

configured to secure an impeller or the like onto a shaft.

6. The assembly of Claim 4 wherein the shaft and impeller or the like are

manufactured and initially assembled with a slip fit, which slip fit becomes an interference fit upon tightening of the coaxial bolt.

7. A multi jackbolt assembly used to secure an impeller or the like onto its shaft, further comprising a streamlined cover.

8. The multi jackbolt assembly of Claim 1 as used to secure the impeller of a hydromotive machine to its shaft.

9. The multi jackbolt assembly of Claim 1 further comprising a sealing means to isolate the threads of the bolt from the surroundings of the said assembly.

10. The multi jackbolt assembly of Claim 1 further comprising seals at individual multi jack bolts to isolate the jack bolt threads from the surroundings of said assembly.

11. The multi jack bolt assembly of Claim 1 further comprising jack bolts inclined relative to the axis of rotation and wedges between the jack bolts and the impelli or the like.