INTEGRATED WIND TURBINE POWERTRAIN LUBRICATION SYSTEM

Abstract

A powertrain component (21, 22, 23) for a wind turbine (100) is provided, comprising a powertrain component housing (20) with at least one rotating part (49) and a dry sump 5 lubrication system for lubricating the rotating part (49). The lubrication system comprises a dry sump lubricant tank (51, 52, 53) and a pump (60) for pumping the lubricant from the tank (51, 52, 53) towards a lubricant release point, the lubricant release point being provided at a level above at least part of the rotating part (49) for receiving the lubricant from the tank (51, 52, 53) and allowing the lubricant to lubricate the rotating part (49). 10 The tank (51, 52, 53) is integrated in or directly attached to the powertrain component housing (20) at a level below the at least one rotating part (49).

Claims

1. A powertrain component for a wind turbine, the powertrain component comprising a powertrain component housing with at least one rotating part and a dry sump lubrication system for lubricating the rotating part, the lubrication system comprising: a dry sump lubricant tank, the tank being integrated in or directly attached to the powertrain component housing at a level below the at least one rotating part, a pump for pumping the lubricant from the tank towards a lubricant release point, the lubricant release point being provided at a level above at least part of the rotating part for receiving the lubricant from the tank and allowing the lubricant to lubricate the rotating part.

2. The powertrain component as claimed in claim 1, wherein the pump is a mechanical pump, operatively connected to the rotating part for being mechanically driven thereby for, at least in an electricity producing mode of the wind turbine, pumping the lubricant from the tank towards the lubricant release point.

3. The powertrain component as claimed in claim 1, wherein the powertrain component is a rotor main bearing, a gearbox or a generator.

4. The powertrain component as claimed in claim 1, wherein the tank is directly attached to the powertrain component housing, further comprising a unit drain, provided in the powertrain component housing at a level below the lubricant release point and below at least part of the rotating part, the unit drain being in direct fluid communication with the tank for allowing the lubricant to flow from the powertrain component into the tank.

5. The powertrain component as claimed in claim 4, wherein the unit drain comprises a valve for selectively closing off the route for the lubricant into the tank.

6. The powertrain component as claimed in claim 1, wherein the powertrain component is a gearbox comprising at least two gearbox stages, each gearbox stage having at least one rotating part, the tank being attached to a bottom part of a first one of the gearbox stages.

7. The gearbox as claimed in claim 6, the tank being attached to a bottom part of the first one and to a bottom part of a second one of the gearbox stages.

8. The gearbox as claimed in claim 6, further comprising a gearbox drain, provided in a housing of the first gearbox stage at a level below the lubricant release point and below at least part of the respective rotating part, the gearbox drain being in direct fluid communication with the tank for allowing the lubricant to flow from the first gearbox stage into the tank.

9. The gearbox as claimed in claim 8, further comprising a second gearbox drain, provided in a housing of the second gearbox stage at a level below the lubricant release point and below at least part of the respective rotating part, the second gearbox drain being in direct fluid communication with the tank for allowing the lubricant to flow from the second gearbox stage into the tank.

10. The powertrain component as claimed in claim 1, wherein the powertrain component is a gearbox comprising at least two gearbox stages, each gearbox stage having at least one rotating part, the tank being integrated in a first one of the gearbox stages.

11. The gearbox as claimed in claim 6, further comprising a stage drain, provided in a housing of the second gearbox stage at a level below the lubricant release point and below at least part of the respective rotating part, the stage drain being in direct fluid communication with the first gearbox stage for allowing the lubricant to flow from the second gearbox stage into the first gearbox stage

12. The powertrain component as claimed in claim 1, wherein the mechanical pump is provided inside the powertrain component housing.

13. The powertrain component as claimed in claim 1, wherein the mechanical pump is configured to also pump the lubricant from the tank towards the lubricant release point when the wind turbine is in an idling mode.

14. The powertrain component as claimed in claim 1, further comprising an electrically powered lubricant pump for pumping the lubricant from the tank towards the lubricant release point when the wind turbine is at a standstill.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] For a better understanding of the invention, some embodiments of the invention will now be described with reference to the following drawings, in which:

[0025] FIG. 1 schematically shows a wind turbine in which the current invention could be advantageously used.

[0026] FIG. 2 schematically shows the nacelle of a wind turbine in which the invention is used.

[0027] FIG. 3 schematically shows a side view of a three stage wind turbine gearbox according to the invention.

[0028] FIG. 4 shows a cross section of the gearbox of FIG. 3.

[0029] FIG. 5 shows a rear end view of the gearbox of FIG. 3

DETAILED DESCRIPTION

[0030] FIG. 1 schematically shows a wind turbine 100 in which the current invention could be advantageously used. The wind turbine 100 comprises a tower 10 with on top thereof a nacelle 20, comprising many of the functional parts of the wind turbine 100. A rotor hub 30 is rotatably mounted to the front end of the nacelle 20 and carries a number of rotor blades 40. The wind turbine 100 shown here comprises three rotor blades 40, but wind turbines with more or less rotor blades 40 are also possible.

[0031] FIG. 2 schematically shows the nacelle 20 of a wind turbine 100 in which the invention is used. In operation, wind causes the rotor blades 40 and the rotor hub 30 to rotate. A powertrain, being enclosed by the nacelle 20 converts the rotation of the rotor hub 30 into electrical power. Power cables (not shown) run from the powertrain, down through the tower 10, to the ground, where the electrical power may be used, stored in a battery or transferred to an electrical grid. The powertrain of this wind turbine 100 comprises a main bearing 21, provided for supporting the rotor hub 30 and facilitating its rotation. An output shaft 24, rotating together with the rotor hub 30, forms the input of a subsequent gearbox 22. In the gearbox 22, the rotational speed of the low-speed rotor hub 30 at the gearbox input is converted into a higher rotational speed for the electrical generator 23 at the gearbox output. The electrical generator 23 turns the rotary power of the gearbox output shaft 25 into useful electrical power that can then be transported down through the wind turbine tower 10.

[0032] Lubrication of critical powertrain components is important for ensuring their function. In dry sump lubrication systems as used in the current invention, a lubricant tank 51, 52, 53 is provided at a level below the rotating parts of the respective powertrain components and a pump 60 is used for pumping the lubricant to the respective lubricant release points. In this exemplary embodiment, a pump 60 is provided in the tank 51 of the main bearing. The gearbox tank 52 and the generator tank 53 may each embody their own pumps (not shown), or receive their lubricant from the pump 60 in the main bearing tank 51 via pipes or hoses (not shown) provided for that purpose. If only one pump 60 is used, also the tanks 51, 52, 53 of the different powertrain components should be fluidly connected via hoses or pipes (not shown). In such a situation, it is preferable to have the pump 60 in the lowest positioned tank 51, such that the lubricant from the other tanks 52, 53 will be led there by gravity only.

[0033] The lubricant tanks 51, 52, 53 may be fully integrated in the housings of the powertrain components or directly attached to their bottoms. With a fully integrated tank 51, 52, 53, the lubricant can flow down through the lubricated parts and directly drop down into the tank 51, 52, 53. Optionally, some flow guiding features are added for directing the lubricant flow and avoiding lubricant from the tank 51, 52, 53 to splash up into the functional parts of the powertrain component.

[0034] Alternatively, the lubricant tanks 51, 52, 53 are directly attached to the bottom of the powertrain component housings. In such a configuration, it is preferred to have a unit drain in the bottom of the powertrain component housings through which the lubricant can fall down into the attached tank 51, 52, 53. The unit drain may comprise a controllable valve. Closing off the valve would allow the lubricant level in the powertrain component to rise in order to temporarily create a wet sump lubrication system, which may be desirable when in certain specific conditions.

[0035] The pump 60 may be a standard electrical pump or a mechanical pump 60, operatively connected to and powered by the rotating part of the power train component. For example, a mechanical pump 60 in the main bearing unit 21 could be driven by the rotary motion of the rotor hub 30 or a mechanical pump in the generator housing 23 could be driven by gears that are rotated by the generator input shaft 25. Because, according to the invention, the lubricant tank is integrated in or directly attached to the powertrain component, the mechanical pump 60 can be installed close to the rotating parts that power it as well as to the lubricant it has to pump up to the lubricant release points. With a separate lubricant tank as used in the prior art, a pump at the tank cannot easily be mechanically driven and a pump at the powertrain component needs long connecting pipes or hoses to pump the lubricant from the tank. The main advantage of using a mechanical pump 60 instead of an electrical one is that it doesn't consume any power when the wind turbine is idling and even works when the wind turbine loses its connection to the power grid. The lubrication system according to the invention does not need an electrical pump for normal operation, i.e. when the blades are rotating and the generator 23 produces electricity, or when idling. Optionally, a small auxiliary electrical pump may be provided for lubricating the powertrain components when the wind turbine is at a complete standstill.

[0036] The pump 60 may be installed inside the housing of the powertrain component 21, 22, 23, such that it closest to the gears driving the pump and the lubricant to be pumped up. Alternatively, the pump 60 may be attached to the housing of the powertrain component, such that it is easier accessible for maintenance.

[0037] FIG. 3 schematically shows a side view of a three stage wind turbine gearbox 22 according to the invention. The rotor hub output shaft 24 forms or is connected to the input 24b of the gearbox 22. The gearbox 22 comprises three consecutive stages 31, 32, 33. A common gearbox ratio is about 90:1, with the rotor hub 30 at the input 24b typically rotating at a speed up to 20 rpm and a corresponding 1800 rpm output for the generator 23. Usually, the gearbox 22 comprises three consecutive stages 31, 32, 33. At the input 24b, a planetary stage 31 is provided which is very suitable for handling high torques from the rotor 30. The planetary stage 31 is then followed by two consecutive parallel stages 32, 33 having sets of gears that further speed up the rotation. Alternatively, also the second stage 32 uses a planetary gear set and only the third stage 33 is a parallel stage. Some wind turbines may use lower gearbox ratios, e.g. about 30:1, dispensing with the highest speed stage in a typical gearbox.

[0038] In this gearbox 22, a lubricant tank 52 is provided under the second and third gearbox stages. A mechanical pump 60 is provided in the gearbox housing. A filter arrangement 61 may be provided in between the lubricant tank 52 and the mechanical pump to ensure that only clean lubricant will be used for lubricating the rotating parts of the gearbox 22.

[0039] FIG. 4 shows a cross section of the gearbox 22 of FIG. 3. In this cross section, it is shown how the mechanical pump 60 is driven by a gear 49 in the third stage 33 of the gearbox 22. Also visible are the drains 41 and 43 of the first and third gearbox stages that let the lubricant from the respective gearbox stages flow into the tank 52 directly. Lubricant from the second gearbox stage 32 leaves that stage through a stage drain 42 that releases the lubricant in a lower part of the third gearbox stage 33. From there, it can flow through the drain 43 of the third gearbox stage into the tank 52.

[0040] FIG. 5 shows a rear end view of the gearbox of FIG. 3. The lubricant tank 52 is shown here as a fully integrated feature of the gearbox housing, but it should be clear from the above that alternative arrangements are also possible. The exemplary tank 52 shown in FIGS. 3 and 4 has a length that is about twice the size of its height. From FIG. 5, it is clear that the width of the tank 52 may extend beyond the width of the main part of the gearbox, comprising the rotating parts. An alternative gearbox design may extend over the full length of the three gearbox stages 31, 32, 33. The resulting larger surface area would allow for a reduced height and therefore possibly a more compact design.