A GREASE COLLECTION AND DISCHARGE SYSTEM"

Cross-Reference to Related Applications

This Patent Application claims priority from Italian Patent Application No . 102022000012773 filed on June 16 , 2022 the entire disclosure of which is incorporated herein by reference .

Technical Field

The technical field of this invention concerns heavy mechanics systems , such as , preferably, wind turbines and cable transportation systems , but also earthmoving machines , cranes , li fters , etc . , wherein there are rotating elements connected to fixed parts by means of special bearings . In the details of this invention, such bearings are lubricated with grease and, in this context , this invention will deal with the issue of how to optimise the periodic steps for replacing the lubrication grease of these components .

State of the Art

In the context of heavy mechanics , as in wind turbine and cable transportation systems , it is known to use bearings lubricated with grease to connect moveable parts to fixed parts .

To retain the grease in the coupling portions and to be able to , in any case , replace it when necessary, it is known to provide the above-mentioned bearings with special seals . Referring to the axis of the ring-shaped bearing, the grease is housed in the axial gap between the inner and outer rings and, at the opposite sides of this in the gap, there is a hermetic seal on one side and a lip seal on the other . As known, the lip seal is configured so that the grease leaks out in a controlled way during normal operation of the bearing, as well as during the steps of topping up or changing the grease . Obviously, the used-up grease that has leaked out of the lip seal must be removed periodically to avoid the grease penetrating the other points of the bearing from here .

In large mechanic systems , such as , for example , a cable car system and a wind turbine, these cleaning operations for the used-up leaked grease , as described above , are not very convenient to perform given also the height at which one must operate and, sometimes , it also requires the dismantling of some components . Obviously, said operation involves high costs and long maintenance times .

There is , therefore , the need today to have a new and inventive solution to the problem of removing the used-up, leaked grease as described above in the bearing .

Description of the Invention

The purpose of this invention is , thus , to provide a bearing assembly that reduces the drawback of the prior art described in the preceding chapter regarding the problem of removing the used-up grease .

This invention provides , as a starting point , a known configuration of a grease-lubricated bearing, in particular for wind turbines or cable transportation systems , wherein this bearing is annular shaped around an axis A and comprises :

- an outer ring;

- an inner ring, wherein between the inner ring and outer ring an axial gap is provided filled with lubrication grease and extending from a first side to a second side of the bearing assembly;

- at least one rolling body housed in the gap to allow relative rotation of the rings around the axis A;

- a first hermetic seal and a lip seal respectively at the first and second side of the gap to allow grease to leak out the gap only at the second side of the bearing assembly .

The configuration described up to here corresponds to the current state of the art ( that is also represented in Figure 2 ) and, thus , the person skilled in the art does not require other details to fully understand the implementation thereof .

Starting from thi s known configuration, this invention proposes , in an inventive way, to provide the bearing assembly with an additional element in the form of a sealingholding ring ( claimed as the third ring 11 ) , which will define , with a speci fic seal , a closed collection chamber for grease downstream of the lip seal . In addition, this third ring is provided with a series of channels , ducts , openings , and grooves for creating a discharge circuit configured to carry, in a controlled manner, the grease from the collection chamber outside the bearing assembly . In detail , the new elements that this invention thus involves are :

- the above-mentioned third ring connected to the outer ring of the bearing wherein this third ring has a radial extension towards the axis A at the second side of the bearing to create a portion overhanging and facing ( spaced) the inner ring and the lip seal ;

- a second hermetic seal ( extending basically axial ly) that connects the third ring to the inner ring so as to create a collection chamber for the grease leaked from the gap through the lip seal at the second side ; thus , the collection chamber is delimited by a radial face of the inner ring, the second hermetic seal , the radial face of the third ring facing the inner ring, the portion of the axial face of the outer ring that extends axially beyond the inner ring and the lip seal in the mouth of the gap ;

- a discharge circuit obtained in the third ring with at least one inlet facing the collection chamber ( in fluidic connection) and at least one discharge opening for discharging the grease collected in the collection chamber outside the bearing assembly .

Thus , advantageously, according to this invention, the used-up grease that has leaked out the lip seal in the mouth of the gap cannot penetrate the bearing but finds a discharge route defined by the discharge circuit obtained in the third ring .

The discharge circuit preferably comprises an annular groove (with a circular or square cross-section) obtained in the ring and facing the collection chamber . The discharge circuit comprises , in addition, discharge openings ( at least one ) obtained in the ring and connected fluidically to the annular groove to discharge the grease outside the bearing assembly . These discharge openings may be s imple tangential holes or ends of radial discharge ducts or tangential ones connected to the annular groove .

According to one embodiment , it is possible to provide a device that forces the grease from the groove to the discharge openings , for example a mobile piston device may be provided in the groove to force the grease from the groove to the openings and/or discharge ducts . Still more preferably, the piston device may comprise a piston or plunger with a cross-section basically corresponding to the groove and two cables (preferably metallic ) connected on opposite sides of the piston . These cables serve to control the motion of the piston and may have ends that leave the discharge openings due to the manual actuation of the piston and, therefore , of the grease discharge .

I f there are radial discharge ducts connected to the groove , in the gap are present fixed deflectors at these radial discharge ducts to direct the grease towards the discharge . The discharge ducts being radial , the grease is forced by the rotation itsel f of the bearing towards the discharge and the piston described above is not required .

Again, i f there are radial discharge ducts connected to the groove , in the gap ( also in addition to the def lectors ) there may be partitions connected to the fixed ring during the step for removing the used-up grease to divide the gap into sub-chambers wherein each is connected to at least one radial discharge duct .

There are preferably removable plugs at the discharge openings present on the outer face of the third ring .

Alternatively, or in addition to the above-mentioned plugs , in the gap there may preferably be movable plugs for selectively opening and closing the connection between the gap and the discharge ducts or openings .

As mentioned at the start , this invention finds its most advantageous application in heavy mechanical systems .

This invention extends , in a non-limiting way, in detail to a wind turbine comprising a hub and at least one blade extending along an axis A and coupled to the hub in a rotatable manner in relation to the axis A to modi fy the wing area of the blade exposed to the wind . Advantageously, the blade may be coupled to the hub in a rotatable manner through a bearing assembly as claimed and described in this invention . In particular, in this case , the blade and the hub are coupled on opposite sides of the bearing assembly respectively to the third ring and the inner ring . It should be speci fied, in any case , that the hub and the blade may be understood, generically, as a first and second body of the wind turbine and, in this sense , the bearing of this invention may be integrated in the turbine in other positions too to connect di f ferent components . For example , in a wind turbine , the bearing of this invention may be provided as a "main-bearing" and/or "yaw-bearing" , i . e . , bearings interposed respectively between the hub and nacelle and between nacelle and tower head ( the person skilled in the art knows these elements well ) .

Another preferred area in which to integrate this invention is that of cable transportation systems . In this sense , this invention also extends to a cable transportation system that comprises a hauling cable , at least one passenger transport unit coupled to the hauling cable , a pulley coupled to the cable to haul the cable rotating around the axis A, a pulley support structure ; wherein the pulley is coupled to the support structure in a rotatable manner through a bearing assembly as claimed and described in this invention . In particular, the pulley and the support structure are coupled on opposite sides of the bearing respectively to the third ring and the inner ring .

Of course , other technical areas of heavy mechanics with bodies in relative rotation may also be improved thanks to this invention . For example , a bearing assembly according to this invention may be integrated into earthmoving machines , cranes , li fters , etc .

List of Drawings

This invention will now be described with reference to the attached drawings that illustrate some non-limiting embodiments thereof , in which :

- Figure 1 is a schematic view of a wind turbine that may be improved thanks to this invention;

- Figure 2 is a cross-section view of a portion of a bearing according to the prior art ;

- Figure 3 is a cross-section view of a portion of a first example of a bearing assembly according to this invention;

- Figure 4 is a schematic view of an accessory device of the bearing assembly in Figure 3 ;

- Figures 5 and 6 are cross-section views of portions of a second example of a bearing assembly according to this invention;

- Figures 7 and 8 are cross-section views of portions of a third example of a bearing assembly according to this invention .

Description of an Embodiment of the Invention

Figure 1 shows a schematic view of a wind turbine that may be improved thanks to this invention . As indicated above , this wind turbine is an example of a system that may be improved according to this invention . In particular, Figure 1 shows a wind turbine 20 comprising a hub 21 that supports three blades 22 in which each blade 22 extends along its axis A. As known, each blade 22 is coupled to the hub 21 in a rotatable manner in relation to the axis A to enable the modi fication of the wing area of the blade 22 to be exposed to the wind . To this end, therefore , each blade 22 is coupled to the hub 21 in a rotatable manner through a bearing and this bearing may be a bearing as sembly 1 according to this invention . Of course , other bearing assemblies according to this invention may be installed in the wind turbine 20 in other, di f ferent positions . As mentioned above , both the application to the sector of wind turbines and the speci fic example of the support of the blade on the hub are only nonlimiting applications of this invention . For example , again in a wind turbine , the bearing assembly of this invention may be provided instead of the common bearings used today as a "main-bearing" and "yaw-bearing" , i . e . , bearings interposed respectively between the hub and nacelle and between nacelle and tower head ( the person skilled in the art knows these elements well ) .

Figure 2 is a cross-section view of a portion of a bearing according to the prior art that connects the hub 21 to a blade 22 of the wind turbine 20 in Figure 1 . As can be seen, this known bearing 1 ' is annular around the axis A and comprises :

- an outer ring 3 ,

- an inner ring 4 , wherein between the inner ring 4 and outer ring 3 an axial gap 5 is provided filled with lubrication grease and extending from a first side 7 to a second side 8 of the bearing assembly 1 ;

- two rolling bodies 6 housed in the gap 5 to allow relative rotation of the rings 3 , 4 around the axis A;

- a first hermetic seal 9 and a lip seal 10 respectively at the first side 7 and at the second side 8 on opposite sides of the gap 5 to allow grease to leak out the gap 5 only at the second side 8 of the bearing assembly 1 ' .

In this example , it is the outer ring 3 that rotates while the inner ring 4 is fixed . In any case , according to this invention it is possible to have di f ferent couplings in which it is the inner ring 4 to rotate while the outer ring 3 is fixed .

Starting from thi s known structure , the Figures 3 , 5- 6 , and 7- 8 show, respectively, a first , a second, and a third example of a bearing assembly 1 according to this invention . In the example of Figure 3 , the bearing assembly 1 according to this invention comprises all the elements present in the known bearing 1 ' of Figure 1 to which a third ring 11 was added between the blade 22 and the outer ring 3 . As can be seen, this third ring 11 connected to the outer ring 3 , for example using screws , extends radially toward the axis A at the second side 8 so that it has a portion facing the inner ring 4 and the lip seal 10 . In the inner portion, the third ring supports a second hermetic seal 12 connecting the third ring 11 itsel f to the upper surface of the inner ring 3 for creating a collection chamber 13 for grease leaking from the gap 5 through the lip seal 10 at the second side 8 . In this chamber 13 , the grease is collected only temporarily because in the ring 11 a discharge circuit was formed configured to discharge the grease collected in the collection chamber 13 outside the bearing assembly 1 . In this example , the discharge circuit comprises an annular groove 14 facing the collection chamber 13 connected fluidically to discharge openings , potentially plugged with special removable plugs , again obtained in the ring 11 facing outside the bearing assembly 1 . To force the migration of the grease from the annular groove 14 to the discharge openings , the figure shows a piston device 15 , which is mobile in the groove 14 , comprising a piston or plunger 16 and two cables 17 connected on opposite sides of the piston 16 and that leave the tangential discharge openings due to the manual actuation of the piston and, therefore , of the grease discharge . The second embodiment shown in Figures 5 and 6 di f fers from the example above due to the fact that the discharge openings 18 are radial and connected to radial discharge ducts 19 obtained, again, in the third ring 11 in fluidic communication with the groove 14 . As can be seen in Figure 6 , in this example , there are deflectors 20 ' provided in the gap 14 at the radial discharge ducts 19 to direct grease to the radial discharge ducts 19 . The motion of the grease in this example can be forced by the rotation of the blade 22 .

In relation to the example above , in the third example of Figures 7 and 8 , in the gap 14 there are , additionally, partitions 21 ' that are integral with the inner ring 4 , possibly also mobile , to force the flow towards the discharge ducts 18 .

Lastly, it is clear that modi fications and variations may be made to the invention described herein without departing from the scope of the present invention, as described in the appended claims .