WO2010040027A2

WO2010040027A2 - Grease purge system

Info

Publication number: WO2010040027A2
Application number: PCT/US2009/059334
Authority: WO
Inventors: Mark A. Joki
Original assignee: The Timken Company
Priority date: 2008-10-02
Filing date: 2009-10-02
Publication date: 2010-04-08
Also published as: WO2010040027A3

Abstract

A bearing assembly comprising a rotating outer race (1) supported on sets of rollers (3) relative to inner race (2) with one or more lubricant charge devices (7) adapted to facilitate the controlled purging of used grease from the bearing chambers (3A). Each lubricant charge device (7) is secured to a rotating component of the bearing assembly, in operative relationship to an adjacent stationary surface (2A), and includes an entrapment surface (14A) defining a grease entrapment region (14). As the lubricant charge device (7) is rotationally carried past one or more grease purge port orifices (9), used grease accumulated within the grease entrapment region (14) is forced into the orifice (9) by the entrapment surface (14A) for subsequent extraction through the purge port (8).

Description

GREASE PURGE SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to, and claims priority from, U.S. Provisional Patent Application Serial No. 61/102,101 filed on October 2, 2008, and which is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable. BACKGROUND OF THE INVENTION

The present application is related generally to lubrication systems for large tapered roller bearings, and in particular, to a method and apparatus for purging precise quantities of used grease or lubricant from a roller bearing assembly without the need to excessively increase internal bearing pressures through the injection of large quantities of new grease or lubricant.

In large tapered roller bearings that are used on wind power turbines, it is desirable to remove lubricating grease after the grease has served as a lubricant for a period of time due to the introduction of contaminates into the grease as well as a possible breakdown of the lubricating characteristics. To maintain a proper amount of grease in the bearing, frequent addition of small quantities is ideal. However, it is often necessary to add a large amount of grease to build sufficient pressure within the bearing to force out the used grease. The process of forcing out used grease utilizes excessive amount of new grease, and requires generating high internal pressures within the bearing which can dislodge seals or cause excessive wear of the seals.

Accordingly, it would be advantageous to provide a system and method by which used grease may be extracted from a bearing assembly in precise amounts, and which does not require the use of increased internal grease pressures within the bearing assembly to eject used grease or lubricants. BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present disclosure provides a bearing assembly comprising a rotating outer race supported on sets of rollers relative to an inner race, with one or more lubricant charge devices adapted to facilitate the controlled purging of used grease from interior bearing chambers and spaces. Each lubricant charge device is secured to a rotating part of the bearing assembly, in operative relationship to an adjacent stationary surface, and includes an inclined surface defining a grease entrapment region. As the lubricant charge device is rotationally carried past one or more grease purge port orifices disposed in the stationary surface, used grease accumulated within the grease entrapment region of the lubricant charge device is forced into the grease purse port orifice by the inclined surface for subsequent extraction through the purge port.

In an alternate embodiment, each lubricant charge device further includes a sidewall portion adjacent to the inclined face. The sidewall portion is configured to redirect escaping quantities of used grease towards the rollers.

In an alternate embodiment, each lubricant charge device is coupled to the rotating component of the bearing assembly by a flexible attachment means configured to maintain the lubricant charge device in an operative relation to the adjacent stationary surfaces.

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 is a partial cross section of a bearing assembly, cut along the bearing centerline, illustrating a lubricant charge device of the present disclosure coupled to the rotating outer race; Figure 2 is a partial cross section of the bearing assembly cut normal to the bearing centerline, illustrating a lubricant charge device of the present disclosure coupled to the rotating outer race;;

Figure 3A is an orthographic end view of a lubricant charge device of the present disclosure with directional flow characteristics;

Figure 3B is an orthographic side view of the lubricant charge device shown in Fig. 3A;

Figure 4 is a view of an alternate configuration of a lubricant charge device of the present disclosure incorporating a flexible lubricant collection element;

Figure 5 is a perspective view of an alternate configuration of a spring- loaded lubricant charge device;

Figure 6A is a side view of the lubricant charge device of Fig. 5;

Figure 6B is a bottom view of the lubricant charge device of Fig. 5; and Figure 6C is a front end view of the lubricant charge device of Fig. 5.

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. -A-

Referring to Figure 1 , a self-contained bearing assembly comprises a rotating outer race 1 supported by sets of rollers 3, and an inner race 2. The rollers 3 are spaced circumferentially by a cage 4. Seals 5, carried by a seal support ring 6 coupled to the outer race 1 , are located axially outwards of the rollers 3, between the outer race 1 and an annular surface 2A of the inner race 2 and define a chamber 3A inside the bearing assembly, which optionally, may include a suitable vent to maintain the bearing chamber at atmospheric pressure. Grease or other suitable lubricant is injected at the inner race 2 through a lubricant inlet passage 12 leading to the bearing chamber 3A spaces. Preferably, the lubricant is injected directly at the small end of each row of rollers so the amount of lubricant entering each row is controlled directly. To facilitate removal of old or excess lubricant, a lubricant purge port 8 is disposed in the inner race 2, and extends radially from the outer circumferential surface 2A of the inner race to an inner axial surface 2B. The lubricant purge port 8 preferably has an inner radius which is sufficiently large enough to minimize flow resistance for lubricants passing there through. To facilitate removal of the lubricants from the lubricant purge port 8, a fixed displacement pump 10 may be connected to the discharge side of the lubricant purge port 8 adjacent the surface 2B. The discharge pump 10 may be of a reciprocating piston type, a rotary gear type, or any other suitable discharge mechanism, and preferably is capable of drawing a volume of grease or lubricant through the lubricant purge port 8 which exceeds the volume of grease or lubricant delivered to the bearing chambers 3A at the lubricant inlet passage 12. preventing an accumulate of excess grease or lubricant within the bearing assembly.

During operation of the bearing assembly, rolling movement of the rollers 3 tends to move grease within the bearing chamber from the vicinity of the grease inlet passage 12, axially outwards towards the lubricant purge port 8, at which point a mixture of air and grease will haphazardly enter the lubricant purge port 8. The mixture of air and grease within the lubrication purge port 8 may not move or flow smoothly in response to suction applied by the displacement pump 10 due to the presence of entrapped pockets of air.

To reduce the introduction of air into the lubricant purge port 8, an orifice 9 which opens in response to sufficient applied pressure, is placed in the entrance to the lubrication purge port 8. A lubrication charge device 7 is attached to a rotating component of the bearing assembly such as the seal support ring 6 or the outer race 1 to inject grease or lubricant into the lubrication purge port 8 through the orifice 9 with a minimal introduction of air as the bearing assembly rotates. Referring to Figure 2, grease in the area of the lubricant purge port 8 is forced into the orifice 9 by the lubricant charge device 7 during rotation of the outer race 1 relative to the inner race 2. The lubricant charge device 7 includes a lubricant entrapment surface or face 14 which is inclined circumferentially in the direction of rotation, forming a grease capturing region 14A between the entrapment surface 14 and the circumferential surface 2A of the inner ring 2. As the lubricant charge device 7 rotates past the orifice 9, the accumulation of captured grease is forced through the orifice 9 under pressure and into the lubricant purge port 8 by the entrapment surface 14, fully filling the orifice 9 and minimizing the introduction of air pockets into the lubricant purge port 8.

Because the orifice 9 is fully filled with the used grease, the suction generated by the displacement pump 10 creates a vacuum in the lubricant purge port 8 even though the purge port 8 may still contain a mixture of air and used grease. The vacuum in the purge port 8 increases with time to whereby the grease charged into the orifice 9 is pulled into the lubrication purge port 8. As the orifice 9 successively charges and unloads, the used grease moves through the lubrication purge port 8, and is evacuated from the bearing assembly by the displacement pump 10.

A close relationship between the lubricant charge device 7 and the inner race 2 is required to deliver a sufficient charge of used grease into the orifice 9. There may be a close dimensional relationship with 0.0 to 0.010 inches of clearance between the lubricant charge device 7 and the surface 2A. To maintain the desired dimensional clearance, the lubricant charge device 7 may be secured to the rotating member of the bearing assembly by a flexible coupling so that it rides directly on the surface 2A of the inner race 2 with a light force. A flexible element limits the force applied between the lubricant charge device 7 and the surface 2A of the inner race 2 when the lubricant charge device 7 is mounted in dimensional interference with the inner race 2. The flexible element additionally maintains a zero clearance with dimensional changes caused by deflections and geometric errors. Alternatively, as shown in Figure 4, the lubricant entrapment surface or face 14 may be replaced by a flexible element 15, which maintains a contact with the surface 2A of the inner race 2 as the lubrication charge element 7 is rotationally carried by the outer race 1 , and acts to sweep or collect the lubricant in the grease capturing region 14A.

Preferably the lubricant charge device 7 may have a directional nature so that used grease escaping in an axial direction from the sides of the lubricant charge device 7 is directed away from the seal 5, and back towards the rollers 3. Referring to Figures 3a and 3b, alternate configurations of the charging device 7 are shown, each of which includes a dam 13 disposed on an axially outward side opposite the rollers 3, and which is configured for blocking used grease from flowing axially out of the entrapment region 14A towards the seal 5, and for encouraging the grease to flow back toward the rollers 3. In a second alternative embodiment, as shown in Figures 5 and 6A-6C, a lubricant charge device 70 for charging the orifice 9 of a lubricant purge port 8 may include a spring mounting feature to maintain a desired contact load between a base 71 or "shoe" of the lubricant charge device 70 and the surface 2A over which the base 71 is riding. The lubricant charge device 70 features an entrapment pocket 72 disposed in a lower portion of the front face 73 for trapping grease by motion lubricant charge device 70 relative to the riding surface 2A. A sloped inner surface 74 of the pocket 72, preferably at a 40 degree incline to the riding surface 2A, creates a pressure in the entrapped grease, while the sidewalls 72a and 72b of the pocket 72 prevent the grease from laterally escaping the entrapment pocket 72. As best seen in Figure 5 and 6B, the sidewall 72a is longer than the sidewall 72b, so that excess grease ejects from the pocket 72 from the side which is away from the bearing seal 5 and towards the bearing rolling elements 3. While shown as flat in the Figures, it will be recognized that the base 71 may have a surface contour which matched to the curvature of the surface 2A over which it is riding.

Referring to Figures 5 and 6A, the spring mounting feature of the lubricant charge device 70 may be seen the "hinge" action of the body 7OA of the structure itself, formed in an elongated U-shape, supplemented with a metal spring element 75A disposed in a bore 75 between the free ends of the "U"-shaped body 7OA, to counteract the tendency of the body material to creep towards a stress relieving configuration over time. Preferably the body 7OA may be made of a thermoplastic or PTFE for low wear, but those of ordinary skill in the art will recognize that other suitable materials may be utilized as well.

During use, the lubricant charge device 70 is installed in the bearing assembly by attachment to the rotating member, either directly, or indirectly such as by attachment to the seal carrier ring 6. The lubricant charge device 70 is positioned such that the "hinge" action of the body 7OA results in a flexible engagement between the base 71 and the surface 2A against which the lubricant charge device 70 is disposed. Rotation of the bearing assembly in the direction of the pocket 72 carries the lubricant charge device 70 over the surface 2A, collecting grease or lubricant into pocket 72 for discharge as the pocket 72 is carried periodically carried over the orifice 9. 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. For example, it will be noted that the bearing assembly may include more than one lubricant charge device 7 or 70 and/or more than one orifice 9 together with associated purge ports 8. It will further be noted that while the present disclosure describes the lubricant charge device 7 or 70 as being carried by the rotating member of the bearing and facing the annular surface 2A of the stationary member, the lubricant charge device 7 or 70 may be adapted to be carried by the stationary member of the bearing, with annular surface 2A referring to the rotating member, such that the lubricant discharge orifice (9) and port (8) are disposed in the annular surface of the rotating member. With such a configuration, the rotational movement of the rotating member would continuously move the annular surface of the rotating member into the entrapment region (14A), accumulating used lubricant or grease for periodic discharge into the lubricant discharge orifice (9) and port (8).

Claims

CLAIMS:

1. A lubricant discharge system for use in a bearing assembly comprising an outer race (1 ) supported on sets of rollers (3) for rotational movement relative to an inner race (2), having interior bearing spaces (3A) into which a lubricant is delivered through a lubricant passage (12), and at least one lubricant purge port (8) through which used lubricant is discharged from the interior spaces, comprising: a lubricant charge device (7) supported by a first component of the bearing assembly in operative proximity to a surface (2A) of a second component of the bearing, axially outward from said set of rollers and said interior bearing spaces, said first and second components of said bearing having a relative rotational movement there between; wherein said lubricant charge device (7) includes a lubricant entrapment surface (14) defining a lubricant entrapment region (14A) between said lubricant entrapment surface (14) and said surface (2A) of said second component of the bearing assembly, said lubricant entrapment region (14A) configured to entrap lubricant accumulated on said surface (2A) axially outward from the set of rollers and the bearing interior spaces; and wherein said lubricant charge device (7) is disposed to pass said lubricant entrapment region over at least one lubricant discharge orifice (9) during relative rotation of said first and second components of said bearing, whereby accumulated lubricant contained within said lubricant entrapment region (14A) is forced into said at least one lubricant discharge orifice (9) by said lubricant entrapment surface (14) as said lubricant charge device (7) is rotationally carried over said lubricant discharge orifice (9).

2. The lubricant discharge system of Claim 1 wherein said lubricant entrapment surface (14) is inclined in the direction of relative rotational movement of said lubricant charge device (7).

3. The lubricant discharge system of Claim 1 wherein said lubricant entrapment surface (14) is flexible to accommodate variations in radial spacing between said first component of said bearing carrying said lubricant charge device (7) and said second component of said bearing carrying said surface (2A).

4. The lubricant discharge system of Claim 1 further including a second lubricant entrapment surface (13) disposed adjacent to said first lubricant entrapment surface (14), said second lubricant entrapment surface (13) configured to redirect an axially outward flow of lubricant within said entrapment region (14A) axially inwards towards said set of rollers during relative rotational movement between said first and second components of said bearing.

5. The lubricant discharge system of Claim 1 wherein said lubricant charge device (7) is coupled to said first component of said bearing by a flexible member, said flexible member adapted to maintain said lubricant charge device (14) in operative proximity to said surface (2A) of said second component of said bearing during relative rotational movement there between.

6. The lubricant discharge system of Claim 1 wherein a displacement pump (10) is operatively coupled to said lubricant purge port (8) opposite from said lubricant discharge orifice (9), said displacement pump (10) configured to draw lubricant from said lubricant discharge orifice (9), through said lubricant purge port (8).

7. The lubricant discharge system of Claim 1 wherein said first component of said bearing is the outer race (1 ); and wherein said second component of said bearing is the inner race (2).

8. The lubricant discharge system of Claim 7 wherein the lubricant charge device (7) is supported by a seal support ring (6) coupled to said outer race (1 ) and carrying a seal (5) disposed between said inner race (2) and said outer race (1 ).

9. The lubricant discharge system of Claim 1 wherein at least a portion of said lubricant charge device (7) defining said lubricant entrapment region (14A) is biased towards said surface (2A) of said second component of the bearing assembly.

10. The lubricant discharge system of Claim 8 wherein said lubricant charge device has a "hinge" configuration (70A) providing said bias towards said surface (2A).

1 1. The lubricant discharge system of Claim 8 wherein said lubricant charge device has a generally elongated U-shaped body (70) with a upper portion and a lower portion coupled by a hinge region (70A), said lower portion of said body (70) defining said lubricant entrapment region (14A); and further including a spring member (75A) disposed between said upper portion and said lower portion of said body (70) configured to provide said bias of said lower portion towards said surface (2A) of said second component of the bearing assembly.

12. A method for delivering a charge of lubricant to a lubricant discharge port (8) of a bearing assembly having a rotating component supported on a set of rollers (3) for rotational movement relative to a stationary component, comprising: accumulating, in a lubricant entrapment region (14A), a volume of lubricant from an annular surface (2A) within which said lubricant discharge port (8) is disposed, said annular surface (2A) disposed axially outward from said set of rollers; periodically discharging a quantity of said accumulated volume of lubricant from said lubricant entrapment region (14A) into said lubricant discharge port (8), as said lubricant discharge port (8) passes said lubricant entrapment region (14) due to relative rotational movement between said stationary component and said rotating component of said bearing.

13. The method of Claim 12 further including the step maintaining said lubricant entrapment region (14A) in proximity to said annular surface (2A) to within a selected tolerance.

14. The method of Claim 12 wherein said step of accumulating said lubricant within said lubricant entrapment region (14A) further includes generating a pressure on said accumulated lubricant; and wherein said step of periodically discharging a quantity of said accumulated volume of lubricant further includes extruding said quantity of accumulated lubricant through a lubricant discharge orifice (9) in said lubricant discharge port (8) when said generated pressures in said lubricant entrapment region (14A) reaches at least a threshold required to open said lubricant discharge orifice (9).

15. The method of Claim 12 further including the step of directing a flow of lubricant from said lubricant entrapment region (14A) axially inward within said bearing assembly and towards said set of rollers.