Abstract:
A bearing oil supply assembly includes (a) a plate member with opposed first and second sides, the plate member having a first bore formed in the first side which is adapted to receive a first bearing; (b) an annular manifold attached to the plate member such that the plate member and the manifold cooperatively define an annular oil gallery; and (c) a plurality of passages formed in the manifold, the passages cooperating with the plate member to define a plurality of generally axially-directed pathways in fluid communication with the first bore and the oil gallery. The passages are substantially evenly spaced around the circumference of the manifold. The oil supply assembly may be used to supply oil to two bearings carrying separate shafts running at different speeds.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to bearings, and more particularly to lubrication of bearings subject to changing axial and radial loads. 
     Lubrication of rolling element bearings usually requires a single jet of oil in the bearing&#39;s load zone. This oil flow is sufficient for most operating conditions encountered by such bearings. However, in some situations, such as large gearboxes for wind turbines, one or more rolling element bearings are required to take axial thrust continuously for short periods of time. A single jet of oil is not sufficient for this running condition. In this condition, lubricating oil must be directed to the roller ends uniformly over the full diameter of the bearing. It is known to provide such lubrication using multiple oil pipes and nozzles, but this increases parts count and creates potential leak points at the multiple connections. It is also known to modify a structural component to include oil supply passages for a bearing. However, this complicates manufacture and increases costs, and places a component at risk for being scrapped because of manufacturing errors. 
     BRIEF SUMMARY OF THE INVENTION 
     These and other shortcomings of the prior art are addressed by the present invention, which provides an annular manifold attached to a plate-like structural member that carries one or more bearings, so that the plate member and the manifold cooperatively define an annular oil gallery. A plurality of passages are formed in the manifold which cooperate with the structural member to define a plurality of generally axially-directed pathways in fluid communication with at least one of the bearings and the oil gallery. The passages are substantially evenly spaced around the circumference of the manifold, so as to promote uniform oil supply to the bearings even under quickly changing load conditions. 
     According to one aspect of the invention, a bearing oil supply assembly for a gearbox includes: (a) a plate member with opposed first and second sides, the plate member having a first bore formed in the first side which is adapted to receive a first bearing; (b) an annular manifold attached to the plate member such that the plate member and the manifold cooperatively define an annular oil gallery; and (c) a plurality of passages formed in the manifold, the passages cooperating with the plate member to define a plurality of generally axially-directed pathways in fluid communication with the first bore and the oil gallery. The passages are substantially evenly spaced around the circumference of the manifold. 
     According to another aspect of the invention, an oil supply assembly for a gearbox includes: (a) a housing; (b) a midplate disposed in the housing having opposed first and second sides, the midplate having a first bore formed in the first side; (c) a first bearing received in the first bore; (d) an annular manifold attached to the midplate opposite the first bearing, such that the midplate and the manifold cooperatively define an annular oil gallery; and (e) a plurality of passages formed in the manifold, the passages cooperating with the midplate to define a plurality of generally axially-directed pathways in fluid communication with the first bore and the oil gallery. The passages are substantially evenly spaced around the circumference of the manifold. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
         FIG. 1  is a partially-sectioned side view of a wind turbine including an oil manifold constructed in accordance with an aspect of the present invention; 
         FIG. 2  is a perspective view of a gearbox of the wind turbine of  FIG. 1 ; 
         FIG. 3  is another perspective view of the gearbox of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the gearbox of  FIG. 2 ; 
         FIG. 5  is a sectional perspective view of a portion of the gearbox of  FIG. 4 , showing an oil manifold constructed in accordance with the present invention; 
         FIG. 6  is a perspective view of a midplate of the gearbox of  FIG. 4 , seen from a downwind direction relative to the wind turbine; 
         FIG. 7  is a perspective view of the midplate of  FIG. 6 , seen from an upwind direction relative to the wind turbine; 
         FIG. 8  is a top plan view of the oil manifold shown in  FIG. 5 ; 
         FIG. 9  is a cross-sectional view of the oil manifold of  FIG. 7 ; and 
         FIG. 10  is a cross-sectional view of a portion of a midplate with an attached manifold, showing an oil flow path thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  depicts a wind turbine  10  including a nacelle  12  mounted on the upper end of a tower  14 . The tower  14  is anchored to the ground via foundations  16 . A rotor  18  having blades  20  is mounted on one end of the nacelle  12 . A rotor shaft  22  couples the rotor  18  to a gearbox  24 , which is in turn coupled to an generator (or alternator)  26 . 
     The gearbox  24 , shown in  FIGS. 2-4 , is a multi-stage planetary unit enclosed within a housing  28 . The gear train comprises a carrier  30  coupled to the rotor shaft  22  and mounted to the housing  28  in an upwind carrier bearing  34  and a downwind carrier bearing  36 . It is noted that the terms “downwind” and “upwind” as used herein refer to directions relative to the intended flow of wind through the wind turbine  10  during operation. These positional terms are used merely for convenience in description; the actual components described herein need not have any particular orientation with respect to the airflow. In the illustrated example, the downwind carrier bearing  36  is a cylindrical roller bearing having an inner race  38 , an outer race  40 , and a plurality of rollers  42  (best seen in  FIG. 5 ) and is configured to withstand axial loads as well as radial loads. A plurality of planet gears  44  rotate with the carrier  30 . Each planet gear  44  includes a primary mesh  48  that engages a stationary ring gear  50 , and a secondary mesh  52  that engages a sun gear  46  which is coupled to a center shaft  54 . The center shaft  54  is splined to a high speed gear  56  that runs in a high speed gear bearing  58 . In the illustrated example, the high speed gear bearing  58  is a cylindrical roller bearing having an inner race  60 , an outer race  62 , and a plurality of rollers  64  (best seen in  FIG. 5 ), and is configured to withstand axial loads as well as radial loads The high speed gear  56  engages a high speed pinion  66  that is in turn coupled to a pinion shaft  68 . The pinion shaft  68  is coupled to the generator  26  and to a hydraulically-actuated parking brake (not shown). 
     Within the housing  28  is a stationary, plate-like member referred to as “midplate”  70 , shown in more detail in  FIGS. 5-7 . The midplate  70  has opposed upwind and downwind sides  72  and  74 , an upwind bore  76  that receives the outer race  40  of the downwind carrier bearing  36 , and a downwind bore  78  that receives the outer race  62  of the high speed gear bearing  58 . Although not shown in  FIG. 5 , the carrier  30  is received in the inner race  38  of the downwind carrier bearing  36 , and the high speed gear  56  is received in the inner race  60  of the high speed gear bearing  58 . The midplate  70  includes a radially-extending flange  80  with an upwind face  82 , an opposed downwind face  84 , and an inner face  86  that spans therebetween. The upwind face  82  joins the upwind bore  76 , and the downwind face  84  joins the downwind bore  78 . 
     The gearbox  24  is a wet sump design in which oil for lubrication and cooling is circulated by an electrically-powered pump  88  (See  FIG. 2 ) and supplied to various gears, shafts, bearings, etc. within the housing  28  in a conventional fashion. 
     In operation, the gearbox  24  converts the relatively high torque, low speed (e.g. about 18 RPM) rotational input from the rotor  18  to a higher speed (e.g. about 1440 RPM), lower torque input suitable for operation of the generator  26 . Because several of the gear meshes in the gearbox  24  are helical rather than spur, substantial axial loads are placed on the gears within when they experience angular acceleration or deceleration relative to each other. 
     One specific high loading condition occurs when the rotor  18  is subjected to an emergency stop. In this situation, the hydraulic parking brake, in response to predetermined operating limits, suddenly applies a strong clamping force to the pinion shaft  68 , rapidly stopping its rotation. The rotor  18 , absorbing energy from the wind, is still applying a large torque to the carrier  30 . Because of the helical gear profiles, a very large thrust is applied to the high speed gear  56  in the “upwind” direction (e.g. toward the rotor  18 ). For example, in a known type of wind turbine  10  rated at about 1500 kW power output, the thrust loads could be in the range of about 110 kN (25,000 lbf.) to about 130 kN (30,000 lbf.). In such a situation, the increase in thrust loading on the high speed gear bearing  58  is nearly instantaneous. Under these conditions, lubrication cannot be reliably provided to the high speed gear bearing  58  by a single oil passage. Accordingly, oil is supplied to the high speed gear bearing  58  using a manifold  90  which is attached to the midplate  70 . 
       FIGS. 8 and 9  illustrate the manifold  90  in more detail. It has a generally annular ring portion  92  with inner and outer edges  94  and  96 . An inner rim  98  extends axially downwind from the periphery of the inner edge  94  to define a central opening  100 , and cooperates with the ring portion  92  to define an L-shaped cross-section. An outer rim  102  extends axially downwind from the outer edge  96  of the ring portion  92 . A square-section land  104  is formed at the intersection of the inner rim  98  and the ring portion  92 . 
     One or more feed holes  106  are formed through the ring portion  92  of the manifold  90 , adjacent to and partially through the outer rim  102 . As shown in detail view “A” of  FIG. 8 , plurality of axially-extending oil supply slots  108  are formed in the inner rim  98 . In the particular example shown, eight oil supply slots  108  are spaced evenly around the periphery of the manifold  90 , although the exact number is not critical. Each of the oil supply slots  108  passes through the land  104  and the radially outer surface of the inner rim  98 . 
     As shown in  FIGS. 6 and 7 , the manifold  90  is mounted to the upstream side  72  of the midplate  70  and received in the upwind bore  76 . In the illustrated example, bolts  110  extend through the midplate  70  and are threaded into mounting holes  112  in the manifold  90  to clamp it to the midplate  70 . Other types of fasteners, adhesives, or bonding techniques (such as brazing or welding) could be used instead of the bolts  110 . When assembled to the midplate  70 , the outer rim  102  seals against the upwind bore  76  and the upwind face  82  of the flange  80 , and the inner rim  98  seals against the inner face  86  of the flange  80 . The assembled midplate  70  and manifold  90  define a 360° oil gallery  114 . 
     The operation of the manifold  90  will now be explained with reference to  FIG. 5 . In operation, pressurized oil is supplied to an oil inlet  116  which passes through the midplate  70  and communicates with the oil gallery  114 . The oil flows radially around to fill the oil gallery  114 . Some oil flows through the feed holes  106  in an upwind direction to supply the downwind carrier bearing  36 . From the downwind carrier bearing  36 , the oil drains to a low spot in the housing  28  and is then recirculated. Oil also flows from the oil gallery  114  radially inward, into the oil supply slots  108 , then axially downwind through the oil supply slots  108 , and discharges substantially directly at the rollers  64  of the high speed gear bearing  58  at several locations around the periphery of the high speed gear bearing  58 . This flow path is shown at arrow “B” in  FIG. 10 . From the high speed gear bearing  58 , the oil drains to a low spot in the housing  28  and is then recirculated. This arrangement provides lubrication oil to the roller ends uniformly over the full diameter of the high speed gear bearing  58 . This ensures that pressurized oil flow can keep abreast of rapidly applied loads. The single manifold structure described herein supplies lubricating oil simultaneously to two separate shafts or other rotating members, i.e. the high speed gear bearing  58  and the downwind carrier bearing  36 , which are rotating at different speeds. Also, importantly, no small or complex machined features (holes, slots, etc.) need be formed in the relatively large and expensive midplate  70  in order to provide this oil flow. This significantly reduces the cost of the midplate  70  and reduces the risk of having to scrap the midplate  70  because of production errors. 
     The foregoing has described an oil manifold for a gearbox. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation, the invention being defined by the claims.