CA1161763A - Viscous damper with rotor centering means - Google Patents
Viscous damper with rotor centering meansInfo
- Publication number
- CA1161763A CA1161763A CA000386292A CA386292A CA1161763A CA 1161763 A CA1161763 A CA 1161763A CA 000386292 A CA000386292 A CA 000386292A CA 386292 A CA386292 A CA 386292A CA 1161763 A CA1161763 A CA 1161763A
- Authority
- CA
- Canada
- Prior art keywords
- rotor
- bearing
- shaft
- blades
- cavity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/16—Arrangement of bearings; Supporting or mounting bearings in casings
- F01D25/162—Bearing supports
- F01D25/164—Flexible supports; Vibration damping means associated with the bearing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C27/00—Elastic or yielding bearings or bearing supports, for exclusively rotary movement
- F16C27/04—Ball or roller bearings, e.g. with resilient rolling bodies
- F16C27/045—Ball or roller bearings, e.g. with resilient rolling bodies with a fluid film, e.g. squeeze film damping
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C19/00—Bearings with rolling contact, for exclusively rotary movement
- F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
- F16C19/24—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for radial load mainly
- F16C19/26—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for radial load mainly with a single row of rollers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2360/00—Engines or pumps
- F16C2360/23—Gas turbine engines
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Support Of The Bearing (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
Viscous Damper With Rotor Centering Means Abstract This invention relates to means for preventing the gap adjacent the tips of the blades of a rotor in a turbine type power plant from increasing as a result of rotor sag occasioned when an oil damped bearing is utilized.
Description
i3 , Description Viscous Damper With Rotor Centering Means Technical Field This invention relates to t:win spool engine and particularly to viscous damped bearings.
Background Art As is well known, it is common practice to support the high speed shaft of a twin-spool gas turbine engine with oil damped radial bearings. It is also generally known that one can change the natural frequency of the rotating pressure field as to avoid instability that comes about due to uncontrollable vibration by spriny loading the viscous damper. Reissue Patent No. 30,210 given to D. F~ Buono, N. G. Carlson, D. H. Hibner and 15 D- C. Moringiello on February 12, 1980 and assigned to the same assignee as this patent application, exemplifies such a system, where a spring is mounted parallel to the viscous damper. This changes the natural fre~uency of the pressure field.
~e have, found that use of viscous dampers in a high speed twin spool engine inherently affects the tip clearance of the rotor. This is a result of the rotor sagging within the clearance provided by the oil film.
Obviously, the increased gap allows an excessive amount of air leakage between the tip of the rotor blade and its adjacent seal resulting in a gain of thrust specific fuel consumption ~TSFC). To avoid this gain in TSFC we provide a centering spring to maintain the concentric clearance of the rotor which avoids the majority of the sag. The spring rate of this system is selected so that it provides maximum support for the rotor weight, for .--given "G" and gyro loads, while maintaining sufficient flexibility to allow oil film damping under conditions of high rotor imbalance.
Disclosure of Invention An object of this invention is to provide a method of preventing rotor sag for a twin spool engine that employs viscous damped bearings.
In accordance with a particular embodiment of the invention, there is provided a rotor enclosed in a casing having a rotatable shaft supporting a plurality of compressor blades at one end and a plurality of turbine blades at an opposite end. At least two bear-ings are axia]ly spaced along the shaft for rotatably supporting the shaft. Fluid damper means on one of the bearings include a cavity adjacent the bearing in which fluid is fed to support the bearing when in the rotating mode. The shaft is distortable as a function of the depth of the cavity and radially displaces the compressor blades a similar amount~ The tips of the blades are sufficiently spaced to prevent touching of the inner diameter of the casing. Means are provided for decreas-ing -the distance of displacement of the tips of the blades including a resilient element attached to the bearing for preventing the bearing from displacing the depth of the cavity.
A feature of the invention is to utilize a centering spring for the viscous damped bearing so that the bearing rotor of the shaft does not bottom against the bottom wall of the reservoir of the viscous damper during aircraft maneuvers. The spring rate of the centering spring is optimized so as to minimize for rotor to case relative motion while maintaining the required amount of motion within the viscous damper.
~, ~6~7~i3 -2a-~ ther features and advantages will be apparent from the speclfication and clalms and from the accom~
panying drawings which illustrate an embodiment of the invention.
Brief Description of Drawings Figure 1 is a partial schematic of the rotor and support system without the inclusion of this invention.
Figure 2 is a partial schematic identical to Figure 1 and showing the damped bearing with the present invention.
Figure 3 is a partial view partly in schematic and partly in section showing the details of the in-vention.
Best Mode for Carrying Out The Invention While this invention is described in its preferred embodiment with a rotor/shaft for a -twin spool gas turbine engine being supported by three bearings, it is to be understood that the scope of the invention is not limited thereto.
To best understand this invention reference is made to Figure 1 which shows the rotor generally illustrated ~' .
by reference numeral 10 being supported by three bearings.
Bearings 12 and 1~ are radial load bearings and bearing 16 is the thrust load bearing. The particular bearings are well known and for further details reference is hereby made to the models JT9D and JTlOD manufactured by Pratt & Whitney Aircraft Group of United Technologies Corporation, the assignee of th:Ls patent application.
As can be seen in Figure 1, the rotor sags because its weight causes it to seat on the bottom of the viscous damper wall. The amount of sag is related to the dis-placement of the bearing relative to the oil damp gap which occurs when the rotor is sllbject to gravitation or gyroscopic loacling. In that instance the weight and inertia of the rotor, that is, shaft 18, stages of compressor blades 20 and stages of turbine blades 22 force the shaft to distort as shown by the bow of center line 24.
Figure 2 represents the same rotor system when employing the present invention. The centering spring 30 suitably supports the bearing so that the gap of the oil damper 32 remains substantially undisturbed when the rotor is subject to aircraft maneuvers.
As is apparent from the foregoing, the viscous damped bearing is located intermediate the compressor and turbine. This is not to be construed as a necessary aspect of this invent;on, as one ordinarily skilled in the art will recognize that the damped bearing can be located in other locations and more than one bearing may be damped.
Hence, by employing centering spring 30, the annular gap defined by the oil reservoir 32 assures that the gap "A" remains substantially the same when the engine is in the static condition. In actual test it was found that the gap allowance could be reduced from .005 inch to .001 inch which represents a considerable benefit in TSFC.
Details of a preferred ernbodiment of a viscous damped bearing centered by a centering spring is shown in Figure 1. As can be seen the roller bearing generall~
illustrated by reference numeral ~0 comprises inner race 42, outer race 44, sandwiching a plurality of rollers 46 (one being shown) retained in its relative positions by cage 48. The inner race 42 is supported to shaft 50 by the end locking members 52 and 54. The outer race 44 is secured into position and supported to ring element 56 by lock nut and rivet assembly 58. The viscous damper is obtained by sealing the ends of support ring 56 with the annular seals 58 and 60 whi~h project beyond the outer surface 62 of support ring 56 and bear against the inner diameter of annular ring 64. Note that the bearing assembly is not supported by the seals 58 but rather are supported by cantilever spring 70. Hence, the bearing is centered by the centering spring which comprises a plurality of cantilevered springs 70 (one being shown).
As noted, one end of spring 70 is secured to the bulk-head or casing support member 72 by the nut assembly 74and the other end is secured to the extension portion 76 of ring element 56 by nut assembly 78.
As is apparent from the foregoing, the centering spring 70 serves to maintain the gap "B" in the oil damper. It is obvious that the centering spring can be made more effective in terms of supporting the rotor as being deslgned for increased stiffness. However, this would result in reduced motion within the ~iscous damper under conditions of rotor imbalance twhirl) loads. Thus the support spring rate must be optimized for the two conflicting requirements.
It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit and scope of this novel concept as defined by the following claims.
Background Art As is well known, it is common practice to support the high speed shaft of a twin-spool gas turbine engine with oil damped radial bearings. It is also generally known that one can change the natural frequency of the rotating pressure field as to avoid instability that comes about due to uncontrollable vibration by spriny loading the viscous damper. Reissue Patent No. 30,210 given to D. F~ Buono, N. G. Carlson, D. H. Hibner and 15 D- C. Moringiello on February 12, 1980 and assigned to the same assignee as this patent application, exemplifies such a system, where a spring is mounted parallel to the viscous damper. This changes the natural fre~uency of the pressure field.
~e have, found that use of viscous dampers in a high speed twin spool engine inherently affects the tip clearance of the rotor. This is a result of the rotor sagging within the clearance provided by the oil film.
Obviously, the increased gap allows an excessive amount of air leakage between the tip of the rotor blade and its adjacent seal resulting in a gain of thrust specific fuel consumption ~TSFC). To avoid this gain in TSFC we provide a centering spring to maintain the concentric clearance of the rotor which avoids the majority of the sag. The spring rate of this system is selected so that it provides maximum support for the rotor weight, for .--given "G" and gyro loads, while maintaining sufficient flexibility to allow oil film damping under conditions of high rotor imbalance.
Disclosure of Invention An object of this invention is to provide a method of preventing rotor sag for a twin spool engine that employs viscous damped bearings.
In accordance with a particular embodiment of the invention, there is provided a rotor enclosed in a casing having a rotatable shaft supporting a plurality of compressor blades at one end and a plurality of turbine blades at an opposite end. At least two bear-ings are axia]ly spaced along the shaft for rotatably supporting the shaft. Fluid damper means on one of the bearings include a cavity adjacent the bearing in which fluid is fed to support the bearing when in the rotating mode. The shaft is distortable as a function of the depth of the cavity and radially displaces the compressor blades a similar amount~ The tips of the blades are sufficiently spaced to prevent touching of the inner diameter of the casing. Means are provided for decreas-ing -the distance of displacement of the tips of the blades including a resilient element attached to the bearing for preventing the bearing from displacing the depth of the cavity.
A feature of the invention is to utilize a centering spring for the viscous damped bearing so that the bearing rotor of the shaft does not bottom against the bottom wall of the reservoir of the viscous damper during aircraft maneuvers. The spring rate of the centering spring is optimized so as to minimize for rotor to case relative motion while maintaining the required amount of motion within the viscous damper.
~, ~6~7~i3 -2a-~ ther features and advantages will be apparent from the speclfication and clalms and from the accom~
panying drawings which illustrate an embodiment of the invention.
Brief Description of Drawings Figure 1 is a partial schematic of the rotor and support system without the inclusion of this invention.
Figure 2 is a partial schematic identical to Figure 1 and showing the damped bearing with the present invention.
Figure 3 is a partial view partly in schematic and partly in section showing the details of the in-vention.
Best Mode for Carrying Out The Invention While this invention is described in its preferred embodiment with a rotor/shaft for a -twin spool gas turbine engine being supported by three bearings, it is to be understood that the scope of the invention is not limited thereto.
To best understand this invention reference is made to Figure 1 which shows the rotor generally illustrated ~' .
by reference numeral 10 being supported by three bearings.
Bearings 12 and 1~ are radial load bearings and bearing 16 is the thrust load bearing. The particular bearings are well known and for further details reference is hereby made to the models JT9D and JTlOD manufactured by Pratt & Whitney Aircraft Group of United Technologies Corporation, the assignee of th:Ls patent application.
As can be seen in Figure 1, the rotor sags because its weight causes it to seat on the bottom of the viscous damper wall. The amount of sag is related to the dis-placement of the bearing relative to the oil damp gap which occurs when the rotor is sllbject to gravitation or gyroscopic loacling. In that instance the weight and inertia of the rotor, that is, shaft 18, stages of compressor blades 20 and stages of turbine blades 22 force the shaft to distort as shown by the bow of center line 24.
Figure 2 represents the same rotor system when employing the present invention. The centering spring 30 suitably supports the bearing so that the gap of the oil damper 32 remains substantially undisturbed when the rotor is subject to aircraft maneuvers.
As is apparent from the foregoing, the viscous damped bearing is located intermediate the compressor and turbine. This is not to be construed as a necessary aspect of this invent;on, as one ordinarily skilled in the art will recognize that the damped bearing can be located in other locations and more than one bearing may be damped.
Hence, by employing centering spring 30, the annular gap defined by the oil reservoir 32 assures that the gap "A" remains substantially the same when the engine is in the static condition. In actual test it was found that the gap allowance could be reduced from .005 inch to .001 inch which represents a considerable benefit in TSFC.
Details of a preferred ernbodiment of a viscous damped bearing centered by a centering spring is shown in Figure 1. As can be seen the roller bearing generall~
illustrated by reference numeral ~0 comprises inner race 42, outer race 44, sandwiching a plurality of rollers 46 (one being shown) retained in its relative positions by cage 48. The inner race 42 is supported to shaft 50 by the end locking members 52 and 54. The outer race 44 is secured into position and supported to ring element 56 by lock nut and rivet assembly 58. The viscous damper is obtained by sealing the ends of support ring 56 with the annular seals 58 and 60 whi~h project beyond the outer surface 62 of support ring 56 and bear against the inner diameter of annular ring 64. Note that the bearing assembly is not supported by the seals 58 but rather are supported by cantilever spring 70. Hence, the bearing is centered by the centering spring which comprises a plurality of cantilevered springs 70 (one being shown).
As noted, one end of spring 70 is secured to the bulk-head or casing support member 72 by the nut assembly 74and the other end is secured to the extension portion 76 of ring element 56 by nut assembly 78.
As is apparent from the foregoing, the centering spring 70 serves to maintain the gap "B" in the oil damper. It is obvious that the centering spring can be made more effective in terms of supporting the rotor as being deslgned for increased stiffness. However, this would result in reduced motion within the ~iscous damper under conditions of rotor imbalance twhirl) loads. Thus the support spring rate must be optimized for the two conflicting requirements.
It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit and scope of this novel concept as defined by the following claims.
Claims (3)
1. For a rotor enclosed in a casing having a rotatable shaft supporting a plurality of compressor blades at one end and a plurality of turbine blades at an opposite end, at least two bearings axially spaced along said shaft for rotatably supporting said shaft, fluid damper means on one of said bearings including a cavity adjacent said bearing in which fluid is fed to support said bearing when in the rotating mode, said shaft being distortable as a function of the depth of said cavity and radially displacing said compressor blades a similar amount, the tips of said blades being sufficiently spaced to prevent touching of the inner diameter of said casing, means for decreasing the distance of displacement of the tips of said blades including a resilient element attached to said bearing for preventing said bearing from displacing the depth of said cavity.
2. For a rotor as in claim 1 wherein said resilient means is a spring having one end attached to said damper and the other end being grounded.
3. For a rotor as in claim 2 wherein the rate of said spring is selected to minimize the deflection of said rotor relative to load manifested thereon by acceleration and gyroscopic forces when the shaft accelerates to its steady state operating speed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US21530280A | 1980-12-11 | 1980-12-11 | |
| US215,302 | 1980-12-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1161763A true CA1161763A (en) | 1984-02-07 |
Family
ID=22802443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000386292A Expired CA1161763A (en) | 1980-12-11 | 1981-09-21 | Viscous damper with rotor centering means |
Country Status (4)
| Country | Link |
|---|---|
| JP (2) | JPS57173613A (en) |
| CA (1) | CA1161763A (en) |
| FR (1) | FR2496169B1 (en) |
| GB (1) | GB2089442B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57179418A (en) * | 1981-04-30 | 1982-11-05 | Hitachi Ltd | Flexible damping bearing |
| US4429923A (en) * | 1981-12-08 | 1984-02-07 | United Technologies Corporation | Bearing support structure |
| US4453783A (en) * | 1981-12-28 | 1984-06-12 | United Technologies Corporation | Bearing support structure |
| US4570045A (en) * | 1984-03-08 | 1986-02-11 | Jeppson Morris R | Conveyorized microwave heating chamber with dielectric wall structure |
| GB8421142D0 (en) * | 1984-08-20 | 1984-09-26 | Brown R D | Damping device |
| US4657410A (en) * | 1986-03-25 | 1987-04-14 | United Technologies Corporation | Nutation damper |
| DE4019720A1 (en) * | 1990-06-21 | 1992-01-09 | Bmw Rolls Royce Gmbh | Through-flow calibration for compressed oil damper - is used with turbine and has housing with roller bearing, outer rings, and seals |
| FR3009843B1 (en) * | 2013-08-26 | 2015-09-25 | Snecma | SUPPORTING COLUMNS OF AN EXTERNAL ROLLING BEARING RING FOR AIRCRAFT TURBOMACHINE, AND METHOD OF MOUNTING THE SAME |
| US9488071B2 (en) * | 2015-03-27 | 2016-11-08 | United Technologies Corporation | Piston ring anti-rotation |
| FR3085408B1 (en) * | 2018-08-28 | 2020-08-07 | Safran Aircraft Engines | TURBOMACHINE IMPROVEMENTS |
| FR3120899B1 (en) * | 2021-03-18 | 2023-05-26 | Safran Aircraft Engines | CENTERING AND GUIDE DEVICE FOR AN AIRCRAFT TURBOMACHINE SHAFT |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB928250A (en) * | 1962-01-12 | 1963-06-12 | Rolls Royce | Bearing |
| GB988500A (en) * | 1964-02-21 | 1965-04-07 | Rolls Royce | Bearing |
| US3456992A (en) * | 1967-04-07 | 1969-07-22 | Curtiss Wright Corp | Vibration damping device |
| GB1421377A (en) * | 1972-04-18 | 1976-01-14 | Rolls Royce | Bearing assemblies |
| US3994541A (en) * | 1975-10-03 | 1976-11-30 | Carrier Corporation | Bearing assembly |
| GB2033024A (en) * | 1978-10-19 | 1980-05-14 | Gen Electric | Bearing assembly with resilient support means |
| US4214796A (en) * | 1978-10-19 | 1980-07-29 | General Electric Company | Bearing assembly with multiple squeeze film damper apparatus |
-
1981
- 1981-09-21 CA CA000386292A patent/CA1161763A/en not_active Expired
- 1981-11-03 GB GB8133038A patent/GB2089442B/en not_active Expired
- 1981-11-30 FR FR8122359A patent/FR2496169B1/en not_active Expired
- 1981-11-30 JP JP56192697A patent/JPS57173613A/en active Pending
-
1990
- 1990-03-16 JP JP1990027115U patent/JPH02119521U/ja active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02119521U (en) | 1990-09-26 |
| GB2089442A (en) | 1982-06-23 |
| JPS57173613A (en) | 1982-10-26 |
| GB2089442B (en) | 1985-03-27 |
| FR2496169A1 (en) | 1982-06-18 |
| FR2496169B1 (en) | 1988-04-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |