A rolling bearing for a wind turbine gearbox; wind turbine gearbox

Abstract

The invention relates to a rolling bearing (1) for a gearbox of a high-speed wind turbine, comprising a first tapered roller bearing (2), on the circumference of which a plurality of first tapered rolling bodies (3) are distributed, and a second tapered roller bearing (4), which is connected to the first tapered roller bearing (2) and which has a plurality of second tapered rolling bodies (5) distributed on the circumference, wherein the first rolling bodies (3) are shorter than the second rolling bodies (5), and wherein the at least one first rolling body (3) and the at least one second rolling body (5) have cavities configured as through-holes (6). The invention also relates to a wind turbine gearbox with a rolling bearing.

Description

[0001] The present invention relates to rolling elements for a high-speed wind turbine gearbox, comprising a first tapered roller bearing (consisting of a plurality of first tapered rolling elements distributed on a circumference) and a second tapered roller bearing (consisting of a plurality of second tapered rolling elements distributed on a circumference) connected to the first tapered roller bearing, wherein the first tapered rolling elements are shorter than the second tapered rolling elements, and thus the two tapered roller bearings (relative to each other) are designed asymmetrically.

[0002] Asymmetric rolling bearings are sometimes known technology that follow the principle of asymmetric design or arrangement of rolling elements.

[0003] For example, publication CN108361276B discloses an asymmetric tapered roller bearing.

[0004] Asymmetric double-row tapered roller main bearings for wind turbine generators are known from publication CN111878507A. The asymmetric double-row tapered roller main bearing for a wind turbine generator consists of a main row tapered roller bearing structure and an auxiliary row tapered roller bearing structure. The load-carrying capacity of the main row tapered roller bearing structure is greater than that of the auxiliary row tapered roller bearing structure, and the two rows of tapered roller bearing structures share a common outer ring. Publication CN206190740U illustrates a self-aligning roller bearing and a wind turbine main shaft drive train system using this bearing. JP2006105208A discloses a double-row self-aligning roller bearing and a wind turbine main shaft support structure.

[0005] In terms of achievable bearing concepts, savings in installation space and material / weight resources, and service life, especially in eccentric force applications, existing bearing concepts have particular drawbacks.

[0006] The objective of this invention is to improve upon the prior art. Known drawbacks will be eliminated or at least minimized.

[0007] In the universal rolling element of the present invention, at least one of the first rolling elements and at least one of the second rolling elements each have a cavity designed as a through hole.

[0008] In other words, modified paired tapered roller bearings can be used for high-speed shafts in wind turbine gearboxes. The internal design of paired single-row bearings / individual bearings is adjusted through rolling element / bearing load design / dimensions. The bearing's rolling elements are hollow, resulting in optimized characteristic curves compared to solid rolling elements.

[0009] Advantageous embodiments are presented in the dependent claims and are explained in more detail below.

[0010] It is more advantageous if the first tapered roller bearing has its own inner and outer housing, and the second tapered roller bearing has its own inner and outer housing. A bearing design with separate inner and outer housings offers the best advantages in bearing installation and allows for the replacement of only one worn bearing, rather than both bearings in a double-row bearing, which is beneficial in terms of both economy and resource efficiency. Furthermore, an X-arrangement of the bearings can be achieved, which can absorb a larger overturning moment under eccentric forces.

[0011] Furthermore, it has been proven advantageous for two bearing inner housings to be directly abutting each other. For the purposes of this invention, it is also conceivable for one end face of the bearing inner housings to be directly joined. Moreover, according to another embodiment of the invention, directly adjacent bearing inner housings and directly adjacent bearing inner housing end faces can be combined together. This bearing arrangement design technically allows forces under application / operating conditions to act on the bearing only from one side.

[0012] Furthermore, it is highly advantageous to install a spacer between the two bearing housings of two tapered roller bearings, contacting both bearings. Ideally, the spacer should be in direct contact with the two adjacent bearings. The advantage of the spacer's design and arrangement is that it is radially flush with the outer surface of the tapered roller bearing housing, resulting in a compact bearing arrangement. This arrangement means that the forces acting during operation are primarily absorbed by the bearings. Therefore, the spacer's installation is beneficial for bearing the forces acting upon it. Additionally, the radial height of the spacer is preferably less than the radial height of the bearing housing, thus preventing contact with the rolling elements. Due to this geometry of the spacer, a technically advantageous clearance is formed between the bearing housing (preferably arranged in pairs) of a single-row bearing, the rolling elements within it, the spacer, and the adjacent bearing inner housing at the lower radial position.

[0013] It is also highly advantageous if all rolling elements of both the first and second tapered roller bearings have a through-hole. The through-hole effectively reduces the weight of the rolling elements and the bearing itself. Another advantage of this design is that by increasing the surface area of ​​the rolling bearing, the free inner surface of the through-hole in the rolling elements dissipates heat more easily. Thus, compared to solid rolling elements, both service life and heat dissipation efficiency can be effectively improved.

[0014] Furthermore, it has been proven advantageous if all through holes of the first tapered roller bearing are of the same size and / or all through holes of the second tapered roller bearing are of the same size. Through holes of the same size offer advantages such as uniform load-bearing capacity, high load-bearing capacity, comparable expected service life, and low production costs for the rolling elements, because all through holes can be produced uniformly as standard through holes.

[0015] If there is a channel on the spacer ring to deliver lubricant to the rolling elements of the first and second tapered roller bearings, allowing the lubricant to enter through through-holes, further advantages can be achieved. This design makes the bearing lubrication method technically more advantageous. Through the channels in the respective spacers, gravity can be used to target the lubricant to areas near the rolling elements, preferably utilizing the channel space between the two rolling elements of a paired tapered roller bearing, each rolling element being in a single row. Because the tapered roller bearings are arranged with their high shoulders facing the channel space, lubricating oil of a predetermined viscosity flowing through the channel space can flow to the rolling elements and through the through-holes on these rolling elements. In the high shoulder region, the dimension / cross-sectional width of the tapered rolling element in the longitudinal direction is preferably larger than in the low shoulder region. The rolling elements are geometrically tapered towards the low shoulder. Due to the high and low shoulders of the bearing, the inclined position of the rolling elements relative to the radial position facilitates the flow of lubricating oil. The lubricating fluid is preferably designed to be both a lubricating fluid and a cooling fluid. For example, one possible form of lubricating fluid is oil. During the flow through the through-hole, the oil will dissipate heat through convection from the inner surface of the rolling element through-hole.

[0016] It is also highly advantageous if the cavity formed by the through-hole occupies between 20% ± 10% and 50% ± 10% of the total volume of the outer contour of each rolling element. Preferably, the cavity occupies 30%, 40%, or 50% of the total volume. This through-hole design allows for advantageous configuration of the rolling elements, thereby advantageously reducing the weight of the rolling elements and the rotational inertia and load of the bearing's conventional rolling element cage. Furthermore, the contact stress between the rolling elements and raceways can be effectively reduced, and lubricating oil flow and circulation channels are realized, thus effectively improving the service life of the rolling elements / bearings with through-holes designed according to the present invention.

[0017] Furthermore, the through-hole is preferably threaded. Other threaded or simpler through-hole designs can also be used, such as through-holes achieved through conventional drilling processes. The threaded geometry increases the inner surface area through a smooth inner bore, thereby increasing the area for convective heat dissipation. In addition, the threaded geometry allows for an unstable flow pattern of the lubricating oil, thus advantageously increasing the heat dissipation of the lubricating oil. The threaded profile of the through-hole facilitates the flow of lubricating oil through the tapered rolling elements, which taper towards the lower shoulder of the bearing, and flows from smaller rolling elements to larger rolling elements. The lubrication / wetting conditions of the larger rolling elements are thus improved. For example, a similar profile design is found in the cavity / delivery chamber of a screw pump rotor. The invention also relates to a wind turbine gearbox with rolling bearings.

[0018] In addition to the tapered rollers shown in the illustration, the rolling elements can be further designed as cylindrical rollers or self-aligning rollers as defined in this invention. Besides high-speed shaft bearings for wind turbines, the rolling elements of this invention are also suitable for any technical field involving high-frequency rotation, requiring minimal temperature rise within the bearing, and / or insufficient lubricant supply. Related industries include, but are not exhaustive, raw material and steel processing industries. Motor spindles are also a conceivable application area. The invention will now be described in more detail with the aid of the accompanying drawings. Two preferred embodiments are shown in the figures. They illustrate...

[0019] Figure 1 A schematic diagram of the technology for asymmetric hollow rolling elements of two paired single-row tapered roller bearings according to the present invention.

[0020] Figure 2 Cross-sectional view of the rolling elements of a tapered roller bearing with threaded through holes.

[0021] Figure 3 A graph showing the functional relationship between the relative fatigue strength of a tapered roller bearing and the proportion of hollow volume in the total volume of the rolling elements of the tapered roller bearing.

[0022] The accompanying drawings are merely illustrative and are intended to aid in understanding the invention. Identical elements are labeled with the same reference numerals. Features of the various embodiments may complement or substitute for each other.

[0023] Figure 1 A first embodiment of the rolling bearing 1 according to the present invention is shown. It uses two single-row tapered roller bearings 2 and 4 arranged in pairs. The tapered roller bearings 2 and 4 shown in the figure are of different sizes, so it is necessary to distinguish between the first / smaller tapered roller bearing 2 with the smaller rolling element 3 and the second / larger tapered roller bearing 4 with the larger rolling element 5.

[0024] Rolling elements 3 and 5 are tapered, thus tapering along the length of the rolling elements, and have through holes 6.

[0025] Each tapered roller bearing 2 or 4 has its own inner bearing housing 7 and outer bearing housing 8. Therefore, the inner bearing housings 7 directly abut against each other, that is, they abut against each other at their end faces.

[0026] The bearing housings 8 of tapered roller bearings 2 and 4 are not directly abutting each other, but are kept at a certain distance from each other in the axial direction, which is formed / ensured by spacer 9. Spacer 9 forms a through space 12 between the bearing housings 8 of the two tapered roller bearings 2 and 4, the end faces of rolling elements 3 and 5, and the bearing inner housing 7.

[0027] The through-hole 6 of the rolling elements 3 or 5 of the tapered roller bearing 2 or 4 can enter through the through space 12. The through-hole 6 has an outer wall / inner surface 10. The through-hole 6 has a high shoulder and a low shoulder, the latter located on the side away from the through space 12. There is also a channel 11 on the spacer 9 through which lubricating oil can enter and flow into the through space 12. Therefore, lubricating oil can reach the through-hole 6 through the through space 12. Lubricating oil (such as machine oil) can flow through the corresponding through-hole 6 by tilting the rolling elements 3 or 5 towards the low shoulder on the side of the tapered roller bearing 2 or 4 away from the through space 12.

[0028] As shown in the figure, the asymmetrical design of tapered roller bearings 2 and 4 (including rolling elements 3 and 5) reduces installation space and size requirements while maintaining the same performance. Therefore, the energy density of the gearbox can be effectively improved. Compared to the larger tapered roller bearing 4, the smaller tapered roller bearing 2 can absorb less force, while the larger tapered roller bearing 4 can absorb more force. Because the rolling element 3 in the smaller tapered roller bearing 2 is smaller, frictional losses are lower, and the associated frictional heat input is also lower, which is beneficial for gearbox temperature control and temperature reduction.

[0029] Figure 2 The special design of the through-hole 6 for the rolling bearing 1 used for tapered roller bearings 2 and / or 4 is shown. The through-hole 6 is threaded / spiral. Therefore, the profile of the outer wall 10 resembles a spiral.

[0030] The through-hole 6 determines the hollow volume. The outer contour of each rolling element 3 or 5 determines the volume of its respective rolling element 3 or 5. By setting these two values ​​relative to each other, a hollowness ratio / hollow volume percentage of approximately 30% to approximately 40% can be obtained. The hollowness ratio can be as high as 50%. Furthermore, the smooth design of the inner surface and hole wall structure of the through-hole 6 can be achieved by drilling, or by using a threaded design. The nominal size range and spacing range of the through-hole 6 are preferably predetermined. According to the present invention, numerical simulations of the contact stress of tapered roller bearings 2 or 4 with rolling elements 3 or 5 demonstrate the advantages of the design of rolling elements 3 or 5 / tapered roller bearings 2 or 4 with through-hole 6 compared to the ordinary solid design in the prior art.

[0031] Figure 3 It shows Figure 1 / Figure 2The graph shown illustrates the functional relationship between the relative fatigue strength of the rolling bearing 1 of the tapered roller bearings 2 and 4 according to the invention and the void ratio determined by the through hole 6. The vertical axis of the relative fatigue strength [hours] is marked with reference symbol 13, and the horizontal axis of the void ratio [%] is marked with reference symbol 14. The relative fatigue strength is determined based on discrete data points of 20%, 40%, 50%, 60%, 70%, and 80% of the void ratio 14. Interpolation is performed between the discrete data points to more visually represent the changes in relative fatigue strength. The curves calculated in this way are applicable to four different types of rolling elements 3 and 5: the solid curve marked with reference symbol 15 relates to the first type, namely "Model 1, single combination"; the dashed curve marked with reference symbol 16 is the second type, namely "Model 1, double combination"; the dashed curve marked with reference symbol 17 is the third type, namely "Model 2, single combination"; and the dashed curve marked with reference symbol 18 is the fourth type, namely "Model 2, double combination".

[0032] The curves show that the relative fatigue strength increases continuously when the hollowness is below 50%, reaching its maximum at a hollowness of 50%. When the hollowness exceeds 50%, the relative fatigue strength of the embodiments shown in curves 16, 17, and 18 decreases compared to the maximum value. For the design of rolling bearing 3 or 5" Model 1, single-combination" 15, the increase in relative fatigue strength shows a deviation from the embodiments in curves 16, 17, or 18. Therefore, regardless of the embodiment, only rolling bearings 3 or 5 with a hollowness as high as 50% exhibit a uniform trend in relative fatigue strength 13. The relative fatigue strength as a function of hollowness is determined by different, sometimes contradictory, parameters and their dependence on hollowness.

[0033] For example, load-bearing capacity, contact stress of rolling elements 3 or 5 (determined by effective operating load / external force and internal geometry between rolling elements 3 or 5 and raceway), and bearing heat generation (determined by heat dissipated by rolling elements 3 or 5 through the inner surface of through hole 6 / frictional heat).

[0034] Reference Symbol List

[0035] 1 Rolling bearing

[0036] 2 Smaller tapered roller bearings / First tapered roller bearing

[0037] 3 Larger tapered roller bearing / Second tapered roller bearing

[0038] 4 Smaller rolling element / First rolling element

[0039] 5 Larger rolling element / Second rolling element

[0040] 6 through holes

[0041] 7 Bearing Inner Housing

[0042] 8 bearing housings

[0043] 9 spacers

[0044] 10. Outer wall of the through hole of the rolling element

[0045] 11 channels

[0046] 12 Through Spaces

[0047] 13 Relative fatigue strength

[0048] 14. Hollowness Ratio / Hollow Volume Percentage

[0049] 15 Rolling Element Design "Model 1, Single Combination"

[0050] 16 Rolling Element Design "Model 1, Double Combination"

[0051] 17 Rolling Element Design "Model 2, Single Combination"

[0052] 18 Rolling Element Design "Model 2, Double Combination"

Claims

1. A rolling bearing (1) for a high-speed wind turbine gearbox, comprising a first tapered roller bearing (2) having a plurality of first tapered rolling elements (3) distributed on its circumference, and a second tapered roller bearing (4) connected to the first tapered roller bearing (2) having a plurality of second tapered rolling elements (5) distributed on its circumference, wherein the first rolling elements (3) are shorter than the second rolling elements (5), characterized in that At least one of the first rolling elements (3) and at least one of the second rolling elements (5) have a cavity designed as a through hole (6).

2. The rolling bearing (1) according to claim 1 is characterized in that the first tapered roller bearing (2) has its own bearing inner shell (7) and bearing outer shell (8), and the second tapered roller bearing (4) has its own bearing inner shell (7) and bearing outer shell (8).

3. The rolling bearing (1) according to any one of claims 1 and 2, characterized in that... The two bearing inner shells (7) directly abut against each other.

4. The rolling bearing (1) according to any one of claims 1 to 3, characterized in that, A spacer (9) is installed between the two bearing housings (8) of the two tapered roller bearings (2, 4) and contacts the two tapered roller bearings (2, 4).

5. The rolling bearing (1) according to any one of claims 1 to 4, characterized in that... All rolling elements (3, 5) of the first tapered roller bearing (2) and the second tapered roller bearing (4) have a through hole (6).

6. The rolling bearing (1) according to any one of claims 1 to 5, characterized in that... All through holes (6) of the first tapered roller bearing (2) are the same size, and / or all through holes (6) of the second tapered roller bearing (4) are the same size.

7. The rolling bearing (1) according to any one of claims 1 to 6, characterized in that, The spacer (9) has a channel (11) for supplying lubricating oil to the rolling elements (3) of the first tapered roller bearing (2) and the rolling elements (5) of the second tapered roller bearing (2) so that the lubricating oil can pass through the through hole (6).

8. The rolling bearing (1) according to any one of claims 5 to 7, characterized in that, The through hole (6) defines a cavity that accounts for 20% to 50% of the total volume defined by the outer contour of each rolling element (3, 5).

9. The rolling bearing (1) according to any one of claims 1 to 8, characterized in that... The through hole (6) is spiral-shaped.

10. A wind turbine gearbox with a rolling bearing (1) according to any one of the preceding claims.

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