Patent Application
20080026855
For a more complete understanding of example embodiments of the present invention and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
It should be understood at the outset that although example embodiments of the present invention are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or in existence. The present invention should in no way be limited to the example embodiments, drawings, and techniques illustrated below, including the embodiments and implementation illustrated and described herein. Additionally, the drawings are not necessarily drawn to scale.
Bearings are utilized for axial and radial positioning of rotating assemblies within a system. However, difficulties arise when such systems become large because few, if any, satisfactory axial bearings exist for large rotating assemblies. Additionally, difficulties arise when multiple axial bearings are positioned on opposite ends of such systems because such axial bearings may act against one another with thermal expansion of components within the system. Further exacerbations of such difficulties arise due to requirements for tight tolerances in both axial and radial directions to maintain desired efficiencies.
Accordingly, teachings of some embodiments of the invention recognize a thrust plate/captor plate configuration that maintains relative axial positioning between two rotating assemblies. According to teachings of some embodiments, a thrust plate/captor plate configuration allows for one of the rotating assemblies to be axially located via, for example, axial thrust bearings or other similar configurations while allowing the other rotating assembly to follow the located assembly through excursions related to thermal expansion, vibration, or tolerance stack up. Further details are described below.
The system 100 in the embodiment of
The inner assembly 120 in this embodiment is mounted to the shaft 110 and axially located with an axial and radial locating bearing 165. The inner assembly may include a variety of different positioned components 124, the details of which will vary depending on the particular system. The inner assembly 120 may also include an inner gear 172, which may be part of the inner assembly 120 or separate from the inner assembly 120, but coupled thereto. Further details of the inner gear 172 are described in greater detail below.
The thrust plate 140 in this embodiment is rigidly coupled to and rotates with the inner assembly 120. In particular embodiments, the thrust plate 140 may be considered part of the inner assembly 120. In other embodiments, the thrust plate 140 may be separate from the inner assembly 120. In this embodiment, the inner assembly 120, the thrust plate 140, the shaft 110, and the inner gear 172 all rotate about a shaft axis 112.
The captor plates 150 are rigidly coupled to and rotate with the outer assembly 130. In particular embodiments, the captor plates 150 may be considered part of the outer assembly 130. In other embodiments, the captor plates 150 may be separate from the outer assembly 130. In particular embodiments, the outer assembly 150 may includes an outer gear 176, which may be part of the outer assembly 130 or separate from the outer assembly 130, but coupled thereto. In this embodiment, the captor plates 150, the outer assembly 130, and the outer gear 172 all rotate about an outer assembly axis, which is parallel to the shaft axis 112.
The outer assembly 130 in this embodiment is axially located through the interaction of the thrust plate 140 and captor plates 150. Such an arrangement allows the outer assembly 130 to float with the inner assembly 120, which as described above is axially located with the axial and radial locating bearing 165. In other words, the thrust plate 140/captor plate 150 configuration allows both the inner assembly 120 and the outer assembly 130 to have the same axial reference datum and move together in the axial direction with thermal expansion of the system 100—the outer assembly 130 floating with respect to the inner assembly 120.
The thrust plate 140 in this embodiment is shown sandwiched between the captor plates 150, for example in a cavity 157 formed between the captor plates 150. In particular embodiments, the thrust plate 140 may be a disc with a beveled edge towards a tip 142 of the thrust plate 140. In particular embodiments, the captor plates 150 may have a corresponding receiving portion 152 to receive the tip 142 of the thrust plate 140. The thrust plate 140 and the captor plates 150 are shown as having a point of contact (e.g., via a lubricating fluid) at the tip 142 of the thrust plate 140, for example, at the location indicated by an arrow 190. This point of contact occurs at a pitch line 192.
In particular embodiments, the thrust plate 140 and captor plate 150 only contact one another at or near the pitch line 192. When the thrust plate 140 and the captor plate 150 are at or near the pitch line 192, they have relatively the same velocity. Accordingly, little if any slipping or friction occurs at this point of contact. Moving radially inward from this point of contact at the location of arrow 190 towards the shaft 110, the relative velocity between the thrust plate 140 and the captor plates 150 increase because the outer assembly 130 has a different axis of rotation than the inner assembly 120. Thus,
As briefly referenced above, the outer assembly 130 has a different axis of rotation from the inner assembly 120. Accordingly, contact between the captor plates 150 and the thrust plates 140 does not occur at all locations of the tip 142 of the thrust plate 140. For example, at the point in time of the location of the components of the cross section of the system 100 of
In particular embodiments, lubricating fluid may be injected into the cavity 157 and allowed to accumulate under centrifugal force to a radial level determined by drain holes. The lubricating fluid may include a variety of types of fluid, including, but not limited to lubricating oil. Further details of such a configuration are described with reference to
In this embodiment, the gear assembly 170 includes an inner gear 172 mounted to the inner assembly 120 and an outer gear 176 mounted to the outer assembly 130. The rotation of the shaft 110, the inner assembly 120 and the inner gear 172 may force rotation of the outer assembly 130 or vice versa. The teeth of the inner gear 172 and the teeth of the outer gear 176 contact at the pitch line 192. In other words, in this embodiment, the pitch line 192 is the effect diameter of the inner gear 172.
In particular embodiments, the inner gear 172, itself, may serve as the thrust plate sandwiched between two metal plates 174, which serve as the captor plates. In such an embodiment, the metal plates 174 and the inner gear may be modified to facilitate such a function, for example, in the manners described herein with reference to the thrust plate/captor plate configuration. As one example intended for illustrative purposes only, the inner gear 17 may have a beveled tip with teeth at the very end (to mesh with the outer gear 176) and the metal plates 1 may have a receiving portion, which receives the beveled tips. As another example intended for illustrative purposes only, a cavity may be formed by the metal plates 174 and a lubricating fluid may be injected therein.
In this gear-used-as-thrust plate/captor-plate embodiment, two main points of contact may occur: (1) between the teeth of the inner gear 172 and the outer gear 176, and (2) the edges of the inner gear 172 being pinched between the metal plates 174. In this embodiment, the inner gear 172/metal plate 174 combination (serving as the thrust plate/captor plate combination) may be used solely for the additional axial alignment, not requiring an additional captor plate/thrust plate combination.
In the thrust plate 240/captor plate 250 configuration, excess lubricating fluid may be injected through a passage 253 into a cavity 257. Then, a constant head (e.g., at a fluid level 258) may be maintained by a level control fluid drain 255. Lubricating fluid may also leak radially outward through gaps 259 between the thrust plate 240 and the captor plates 250 and through passage 296. If a displacement of the captor plates 250 with respect to the axially fixed thrust plate 240 occurs, the gaps 259 may become imbalanced and the fluid column on the side with the larger gap 259 passes easily relieving centrifugal pressure while the centrifugal pressure on the side with the smaller gap 259 is maintained. The integration of the differential centrifugal pressure over the areas of the captor plates 250 may results in a restoring force which always forces the gaps 259 to be equal. In this embodiment, no physical contact is experienced between the thrust plate 240 and the captor plates 250.
With reference to
As described above, the embodiments described herein may be used in conjunction with machinery and/or systems including, but not limited to the systems described in U.S. patent application Ser. Nos. 10/359,487; 10/359,488; 11/041,011; and 11/256,364.
Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, variations, alterations, transformation, and modifications.
Pursuant to 35 U.S.C. § 119 (e), this application claims priority from U.S. Provisional Patent Application Ser. No. 60/820,514, entitled SYSTEM AND METHOD FOR MAINTAINING RELATIVE AXIAL POSITIONING BETWEEN TWO ROTATING ASSEMBLIES, filed Jul. 27, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60820514 | Jul 2006 | US |
