WO2009089318A1

WO2009089318A1 - Segmented labyrinth seal

Info

Publication number: WO2009089318A1
Application number: PCT/US2009/030390
Authority: WO
Inventors: Richard Borowski
Original assignee: The Timken Company
Priority date: 2008-01-08
Filing date: 2009-01-08
Publication date: 2009-07-16

Abstract

A segmented labyrinth seal consisting of an assembly of rotor and stator components defining a labyrinth passage, having internal pumping capabilities enhanced by component material properties to provide improved lubricant sealing between the rotating and non-rotating components. Seal component materials are selected to have hydrophobic and hydrophilic characteristics which enhance the pumping capabilities of the labyrinth seal.

Description

SEGMENTED LABYRINTH SEAL

CROSS-REFERENCE TO RELATED APPLICATION

This application derives priority from and claims the benefit of U.S. provisional application 61/019,678, filed 8 January 2008 which is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention relates generally to sealing arrangements between rotating and non-rotating components, and in particular, towards method and apparatus for utilizing labyrinth seal configurations having internal pumping capabilities enhanced by seal component material properties to provide improved lubricant sealing between the rotating and non-rotating components. Rotary shaft seals are designed to prevent lubricants associated with the shaft bearings from leaking externally of the bearing housing, as well as for preventing the ingress of foreign particles from the environment. Foreign particles entering the shaft bearings can contaminate the bearing lubricant, and can result in excessive or destructive wear on the bearing components. There are currently several different designs for labyrinth type seals.

Most of these prior designs consist of two mating machined components that are assembled together axially to create a labyrinth path.. This axial assembly limits the effectiveness of the labyrinth path itself. The need to assembly the two components axially means that there can be not axial interference from either component that could prevent them from "mating." This in turn, limits the labyrinth pathway and prevents the creation of torturous and effective labyrinth pathways.

It would be advantageous to provide a large-size rotary shaft seal, such as a labyrinth seal or dynamic-type shaft seal, with a complicated -?-

labyrinth pathways for improved efficiency for extreme environment applications.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present disclosure provides a labyrinth seal having internal pumping capabilities enhanced by seal component material properties to provide improved lubricant sealing between the rotating and non-rotating components. Seal component materials are selected to have hydrophobic and hydrophilic characteristics which enhance the pumping capabilities of the labyrinth seal. In on embodiment, the labyrinth seal of the present disclosure utilizes a segmented ring member to provide an internal pumping capability in conjunction with a torturous pathway.

The foregoing features, and advantages set forth in the present disclosure as well as presently preferred embodiments will become more apparent from the reading of the following description in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification:

Figure 1 illustrates a sectional cut-away view of a segmented labyrinth seal of the present disclosure disposed adjacent a bearing on a rotating shaft;

Figure 1 A illustrates just the sectional cut-away view of the segmented labyrinth seal of Fig. 1 ;

Figure 2 illustrates a sectional cut-away view of a segmented labyrinth seal of the present disclosure having a tapered or angled labyrinth pathway; Figure 3 is a sectional cut-away view of a segmented labyrinth seal of the present disclosure having a double, complimentary, or parallel angled labyrinth pathway;

Figure 4 is a sectional cut-away view of a segmented labyrinth seal of the present disclosure illustrating a variable labyrinth pathway; Figure 5 illustrates a sectional cut-away view of a segmented labyrinth seal of the present disclosure adapted for installation with a limited housing clearance;

Figure 6 is a variation of the embodiment shown in Fig. 5, incorporating an expulsion or drainage port in the stator outer diameter;

Figure 7 is a sectional cut-away view of a multi-segmented labyrinth seal of the present disclosure;

Figure 8 illustrates the seal of Fig. 7, incorporating an expulsion or drainage port; Figure 9 shows a sectional cut-away view of a segmented labyrinth seal of the present disclosure incorporating metal ring segments for a housing interference fit;

Figure 10 illustrates a concentric rotor ring segment for a segmented labyrinth seal of the present disclosure; Figure 1 1 shows the rotor ring segment of Fig. 10 with a modified surface finish;

Figure 12 illustrates the rotor ring segment of Fig. 10 with outer diameter holes for fluid and air motion;

Figure 13 is illustrates the rotor ring segment of Fig. 10 with an angled outer edge for imparting directional fluid movement;

Figure 14 illustrates a eccentric rotor ring segment for a segmented labyrinth seal of the present disclosure;

Figure 15 illustrates mounting angular offsets or phases for multiple eccentric rotor ring segments to ensure stack balance during rotational movement of the labyrinth seal;

Figure 16 shows the use of stator rivets and rotor rivets to secure components of the segmented labyrinth seal; and

Figure 17 illustrates a sectional cut-away view of a segmented labyrinth seal of the present disclosure having a split stator ring stack. Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. It is to be understood that the drawings are for illustrating the concepts set forth in the present disclosure and are not to scale. 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 the following description or illustrated in the drawings. DETAILED DESCRIPTION

The following detailed description illustrates the invention by way of example and not by way of limitation. The description enables one skilled in the art to make and use the present disclosure, and describes several embodiments, adaptations, variations, alternatives, and uses of the present disclosure, including what is presently believed to be the best mode of carrying out the present disclosure. Turning to the Figures, the present disclosure provides a segmented labyrinth seal design which permits the construction of a labyrinth pathway using segmented components and which allows for axial interference. The segmented components may be assembled in offset and repeating patterns to create a torturous labyrinth pathway having both axial and radial pathways. By utilizing eccentric segments, an internal pumping action may be created within the labyrinth pathways. Additionally, the segmented design allows for the manufacture of large diameter labyrinth seals in a cost effective manner, and permits the use of segments having dissimilar materials, properties, or surface characteristics. For examples, segments may be made from metals (such as aluminum, steel, stainless steel, brass, bronze, etc) or thermoplastics (UHMW, PTFE, Delrin, etc.) as required, and assembled in customized configurations to achieve desired performance levels for an individual application. Individual segments may be machined, sheared, or laser cur from sheet, rod, or tube stock materials, and may be secured together by means of rivets, threaded fasteners, welds, or adhesives, are required. Segments may be split to allow for seal assembly without extensive and expensive disassembly of the supporting structures (i.e. housing or shaft).

As shown in Figures 1 and 1 A, a segmented labyrinth seal of the present disclosure is shown mounted adjacent to a bearing on a rotating shaft. The seal consists of stator and rotor elements, with the stator components supporting one or more O-rings for an interference fit within the surrounding housing. Correspondingly, additional O-ring components carried by the rotor components provide an interference fit against the outer surface of the rotating shaft. Individual inner-diameter and out-diameter components comprise the stator and rotor components, and define an axially concentric "straight" labyrinth pathway through the seal between the lubrication side (adjacent the bearing) and the environmental contaminate side. Alternatively, as shown in Figure 2, by varying the inner and outer diameters of the stator and rotor components, the labyrinth pathway may be directed in a "tapered" or "angled" fashion, increasing the overall path length which must be traversed by lubricants or contaminates. It will be recognized that the overall path length (and path direction) for the labyrinth pathway may be selected based on the particular inner and outer diameters of the stator and rotor segments, such as shown in Figure 3 for a "double-angled" pathway, and Figure 4, for a "variable" pathway.

Where the annular space between the rotating shaft and the housing within which the bearing is secured is limited, the labyrinth seal may be modified to include a reduced diameter portion disposed between the housing and the rotating shaft, and a larger diameter portion which is external to the housing, but still surrounding the rotating shaft, as shown in Figure 5.

As shown in Figure 6, by locating a radial contaminate drainage or expulsion port in the stator components, and the lowest point of the labyrinth seal (generally, the 6 o'clock position for seal having a horizontal axis), outside environmental contaminates, such as water, dust, etc. that enter the labyrinth passage may drain there from prior to reaching the lubricant side of the seal. Correspondingly, as shown in Figure 8, lubricant drainage holes aligned parallel to the axis of rotation may be provided at the lowest point of the labyrinth seal pathways. The lubricant drainage holes pass through one or more stator segments from the lubricant side of the bearing assembly, and allow lubricant which enters the labyrinth pathway adjacent to the rotating shaft to gravity drain to the lowest points of the labyrinth seal passage, and ultimately return to the lubricant side of the bearing.

To increase the effectiveness of the seal in highly contaminated environments, multiple segments of stator and rotor components may be employed, as shown in Figure 7, thereby extending the length of the labyrinth pathway.

It will be recognized that a variety of different materials may be utilized in the assembly of the bearing segments. For example, as shown in Figure 9, the O-ring components carried by the stator segments for sealing against the housing may be replaced with, or used in conjunction with, annular metal ring segments which provide for press-fit engagement with the housing to retain the bearing in-place.

Turning to Figures 10 through 13, various concentric rotor segments are shown. Each concentric rotor segment has an inner diameter sized to fit about the rotating shaft, and an outer diameter sized to define an inner diameter surface of the labyrinth pathway. The concentric rotor segments may be formed from various metals (such as aluminum, steel, stainless steel, brass, bronze, etc), or from various plastics (such as UHMW, PTFE, Delrin, etc), depending upon the particular application for which the seal assembly is to be utilized. The planar surfaces of the concentric rotor segments may be machined to provide textures, or may be coated, to interact with either the lubricant material or any environmental contaminates entering the labyrinth passage. As will be recognized by those of ordinary skill in the art, different textures or coatings may impart hydrophobic or hydrophilic properties to the rotor segments, or may be utilized to provide a pumping action to any fluidic material present within the labyrinth passage. Alternatively, as shown in Figure 12, small holes or passages may be provided through the rotor segment near the outer diameter edge, imparting a turbulent motion to any fluidic material present within the labyrinth passage. Similarly, the actual outer edge of each rotor segment, which defines a "bend" in the labyrinth passage of an assembly seal, may be angled to impart directionality to fluids moving along that surface within the labyrinth passage.

To impart an actual pumping action on fluidic material within the labyrinth passage, eccentric rotor components such as shown in Figures 14 and 15 may be utilized. Each eccentric rotor component has an eccentric outer diameter which acts to pump or drive fluidic material within the labyrinth passage during rotation of the segment. It will be recognized that when utilizing eccentric rotor components, the overall rotating mass of the bearing assembly should be rotationally balanced to ensure balance at high rotational speeds. This may be achieved, for example as shown in Figure 15, by utilized a plurality of eccentric rotor components which are angularly displaced in a balanced configuration.

During assembly of the seal structure, the stator components and rotor components having the desired characteristic for a selected application are coaxially stacked to produce the desired labyrinth pathway. A variety of techniques may be utilized to secure the components in place. For example, as shown in Figure 16, the stator components may be coupled together with a first set of rivets, and correspondingly, the rotor components may be similarly riveted together. Those of ordinary skill will recognized that different means of attachment may be employed, including threaded fasteners, welds, and adhesives, depending upon the particular composition of the various components and the environment within which the seal is to be utilized. To facilitate assembly and disassembly, particular for large-diameter applications, the stator components may be "split" into arcuate segments (each, for example of 180 degrees), offset, and fastened together in an axial direction by suitable mechanical fasteners as shown in Figure 17. This permits the seal assembly to be fitted to a rotating shaft without the need to fully or partially disassembly the rotating shaft or associated structures.

As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

CLAIMS:

1 . A segmented labyrinth seal for fitment between a rotating shaft and a supporting housing, comprising: an assembly of annular rotor segments, said rotor assembly having an inner diameter fitted to the rotating shaft; an assembly of annular stator segments, said stator assembly having an outer diameter fitted to the supporting housing; and wherein said rotor assembly and said stator assembly are coaxially disposed between the rotating shaft and the supporting housing, said annular rotor segments and said annular stator segments defining a labyrinth passage between an environmental contaminate axial end of the seal and a lubricant axial end of the seal.

2. The segmented labyrinth seal of Claim 1 wherein said labyrinth passage is "straight", having inner minimum and outer maximum radial boundaries which are parallel to an axis of the rotating shaft.

3. The segmented labyrinth seal of Claim 1 wherein said labyrinth passage is "tapered", having an inner minimum radial boundary which is parallel to an axis of the rotating shaft, and an outer maximum radial boundary which angles between each of said axial ends, relative to said axis.

4. The segmented labyrinth seal of Claim 1 wherein said labyrinth passage is "angled", having both inner minimum and outer maximum radial boundaries which angle between each of said axial ends, relative to an axis of the rotating shaft.

5. The segmented labyrinth seal of Claim 1 wherein said labyrinth passage is "variable", having at least an outer maximum radial boundary which varies between a minimum radial distance and a maximum radial distance over one-half of the axial dimension of the seal.

6. The segmented labyrinth seal of Claim 1 wherein said assembly of annular stator segments includes a first portion adjacent said lubricant axial end having an outer diameter fitted to the supporting housing, and a second portion adjacent said environmental contaminate axial end having an outer diameter greater than said outer diameter of said first portion.

7. The segmented labyrinth seal of Claim 1 having at least one drainage port within said stator assembly between an external surface and said labyrinth passage.

8. The segmented labyrinth seal of Claim 7 wherein said at least one drainage port is disposed on a circumferential external surface of said stator assembly adjacent said environmental contaminate axial end, said drainage port adapted to drain environmental contaminates from said labyrinth passage.

9. The segmented labyrinth seal of Claim 7 wherein said at least one drainage port is disposed on an axial end surface of said stator assembly adjacent said lubricant axial end, said drainage port adapted to drain lubricants from said labyrinth passage.

10. The segmented labyrinth seal of Claim 1 wherein at least one of said annular rotor segments has inner and outer diameters which are concentric.

1 1 . The segmented labyrinth seal of Claim 1 wherein a plurality of said annular rotor segments have outer diameters which are eccentric relative to an inner diameter, said plurality of eccentric rotor segments disposed in a rotationally balanced configuration within said rotor assembly.

12. The segmented labyrinth seal of Claim 1 1 wherein said eccentric outer diameters of said plurality of rotor segments are configured to pump a fluidic material within said labyrinth passage during rotational movement of said rotor assembly.

13. The segmented labyrinth seal of Claim 1 wherein at least one of said annular rotor segments has an angled circumferential surface, said angled circumferential surface configured to impart movement to a fluidic material within said labyrinth passage during rotational movement of said rotor assembly.

14. The segmented labyrinth seal of Claim 1 wherein an annular surface of at least one of said annular rotor segments is modified to interact with a fluidic material within said labyrinth passage.

15. The segmented labyrinth seal of Claim 1 wherein components of said stator assembly are secured together by an attachment means, said attachment means selected from a set of attachment means including rivets, fasteners, welds, and adhesives.

16. The segmented labyrinth seal of Claim 1 wherein components of said rotor assembly are secured together by an attachment means, said attachment means selected from a set of attachment means including rivets, fasteners, welds, and adhesives.

17. A method for assembling a segmented labyrinth seal for fitment between a rotating shaft and a supporting housing, having a labyrinth passage between opposite axial ends, comprising: selecting a plurality of annular rotor segments, each of said plurality of annular rotor segments having an inner diameter sized for fitment about the rotating shaft, and an outer diameter defining a portion of the labyrinth passage inner boundary; selecting a plurality of annular stator segments, at least one of said plurality of annular stator segments having an outer diameter sized for fitment within the housing, and each of said plurality of annular stator segments having an inner diameter defining a portion of the labyrinth passage outer boundary; and disposing said annular rotor segments and said annular stator segments in a coaxial assembly defining the labyrinth passage between said rotor segment outer diameters and said stator segment inner diameters.