Gearbox, transmission and wind turbine generator system

Abstract

The application provides a gear box, a transmission device and a wind turbine generator set. The gear box comprises a box body, an input structure, an output structure, a first-stage transmission gear train, a second-stage transmission gear train, a third-stage transmission gear train and a fourth-stage transmission gear train. A first-stage inner ring gear of the first-stage transmission gear train is in transmission connection with the input structure. A second-stage inner ring gear of the second-stage transmission gear train is in transmission connection with a first-stage sun gear. A second-stage planet carrier of the second-stage transmission gear train is in transmission connection with the input structure. A third-stage planet carrier of the third-stage transmission gear train is in transmission connection with a second-stage sun gear. The fourth-stage transmission gear train comprises a first spur gear and a second spur gear. The first spur gear is in transmission connection with a third-stage sun gear. The second spur gear is in meshing connection with the first spur gear. The second spur gear is in transmission connection with the output structure. The gear box meets the use demand of a high-power wind turbine generator set for the gear box by taking into account small volume and large speed increasing ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gearboxes, in particular to a gearbox, a transmission device and a wind turbine generator. BACKGROUND

[0002] The core component of a wind turbine generator includes a gearbox, and as the wind turbine generator continues to develop towards high power, the volume and speed-up ratio of the gearbox are increasingly required. For example, a traditional three-stage closed planetary gear train gearbox and a series NGW type planetary gear train gearbox cannot meet the use requirements of a high-power wind turbine generator.

[0003] In addition, the traditional planetary gear train gearbox adopts a flexible pin structure to install the planetary gear, for example, the gearbox disclosed in CN217713604U, the rear end of each planetary carrier is uniformly distributed with a plurality of flexible pin structures in the circumferential direction, each flexible pin structure is connected with the planetary carrier through interference fit, and the flexible pin structure includes an elastic pin shaft sleeve and an elastic pin shaft, the elastic pin shaft sleeve is installed on the elastic pin shaft through interference fit, and one planetary gear is installed on each flexible pin structure through a planetary gear rolling bearing. The flexible pin structure is complex, and the machining and assembly are difficult, resulting in high cost of the gearbox.

[0004] Therefore, how to improve the gearbox is a technical problem to be solved by those skilled in the art. SUMMARY

[0005] To solve the above technical problems, the present application provides a gearbox, which comprises a box body, an input structure, an output structure, a first-stage transmission gear train, a second-stage transmission gear train, a third-stage transmission gear train and a fourth-stage transmission gear train;

[0006] The first-stage transmission gear train comprises a first-stage inner ring gear, a first-stage planetary carrier, a first-stage sun gear and a first-stage planetary gear, the first-stage inner ring gear is in transmission connection with the input structure, the first-stage planetary carrier is fixed with the box body, and the first-stage planetary gear is meshed between the first-stage inner ring gear and the first-stage sun gear;

[0007] The second-stage transmission gear train comprises a second-stage inner ring gear, a second-stage planetary carrier, a second-stage sun gear and a second-stage planetary gear, the second-stage inner ring gear is in transmission connection with the first-stage sun gear, the second-stage planetary carrier is in transmission connection with the input structure, and the second-stage planetary gear is meshed between the second-stage inner ring gear and the second-stage sun gear;

[0008] The third-stage transmission gear train comprises a third-stage inner ring gear, a third-stage planetary carrier, a third-stage sun gear and a third-stage planetary gear, the third-stage inner ring gear is fixed with the box body, the third-stage planetary carrier is in transmission connection with the second-stage sun gear, and the third-stage planetary gear is meshed between the third-stage inner ring gear and the third-stage sun gear;

[0009] The fourth gear train includes a first spur gear and a second spur gear, the first spur gear is in transmission connection with the third sun gear, the second spur gear is in meshing with the first spur gear, and the second spur gear is in transmission connection with the output structure.

[0010] An embodiment of the gear box, one end of the connecting piece close to the input structure is in drum spline connection with the first sun gear, and the other end of the connecting piece away from the input structure is in drum spline connection with the second inner ring gear or fixed with the second inner ring gear.

[0011] An embodiment of the gear box, a region between the two ends of the connecting piece is supported on the first planetary carrier by a first bearing.

[0012] An embodiment of the gear box, the first bearing is a sliding thrust bearing, which can limit the axial position of the first connecting part.

[0013] An embodiment of the gear box, the connecting piece includes a first connecting part and a second connecting part, one end of the first connecting part close to the input structure is supported on the first planetary carrier by a first bearing, and the other end of the first connecting part away from the input structure is fixed with the second inner ring gear, one end of the second connecting part close to the input structure is in drum spline connection with the first sun gear, and the other end of the second connecting part away from the input structure is in drum spline connection with the other end of the first connecting part close to the input structure.

[0014] An embodiment of the gear box, the second sun gear is in drum spline connection with the third planetary carrier.

[0015] An embodiment of the gear box, the first gear train includes a first planetary shaft, both ends of the first planetary shaft are supported on the first planetary carrier, and the first planetary gear is sleeved on the outer periphery of the first planetary shaft; and / or,

[0016] The second gear train includes a second planetary shaft, both ends of the second planetary shaft are supported on the second planetary carrier, and the second planetary gear is sleeved on the outer periphery of the second planetary shaft; and / or,

[0017] The third gear train includes a third planetary shaft, both ends of the third planetary shaft are supported on the third planetary carrier, and the third planetary gear is sleeved on the outer periphery of the third planetary shaft.

[0018] An embodiment of the gear box, one end of the second planetary carrier close to the input structure is in spline connection with the input structure, and the other end of the second planetary carrier away from the input structure is supported on the box body by a second bearing.

[0019] In an embodiment of the gearbox, the area between the two ends of the second planetary carrier is supported on the third planetary carrier by a third bearing.

[0020] In an embodiment of the gearbox, the second planetary carrier is provided with splines; or, the second planetary carrier comprises a second planetary carrier body and a second planetary carrier part, the second planetary carrier part is provided with splines, and the second planetary carrier part and the second planetary carrier body are assembled together.

[0021] In an embodiment of the gearbox, the second planetary carrier body is a casting, and the second planetary carrier part is a forging.

[0022] In an embodiment of the gearbox, the second planetary carrier, the third planetary carrier and the gearbox body are respectively provided with a first labyrinth lubricating oil passage, a second labyrinth lubricating oil passage and an oil inlet passage, and the first labyrinth lubricating oil passage is communicated with the oil inlet passage through the second labyrinth lubricating oil passage.

[0023] In addition, the application further provides a transmission device, which comprises a main shaft, a bearing seat sleeved on the outer periphery of the main shaft and the gearbox as described in any one of the above embodiments, the input structure of the gearbox is fixedly connected with the main shaft, and the gearbox body is fixedly connected with the bearing seat.

[0024] In addition, the application further provides a wind turbine generator, which comprises the gearbox as described in any one of the above embodiments; or, the wind turbine generator comprises the transmission device as described above.

[0025] Compared with the NGW type planetary gear train gearbox in series, the gearbox provided by the application has a more compact structure and a smaller volume, and compared with the three-stage closed planetary gear train gearbox, the gearbox has a larger speed increasing ratio. The gearbox provided by the application takes into account both small volume and large speed increasing ratio, and meets the use requirements of a large-power wind turbine generator on the gearbox. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 a schematic view of a first embodiment of the gearbox provided by the application;

[0027] Figure 2 a schematic view of a second embodiment of the gearbox provided by the application;

[0028] Figure 3 a schematic view of a third embodiment of the gearbox provided by the application;

[0029] Figure 4 a schematic view of a fourth embodiment of the gearbox provided by the application;

[0030] Figure 5 a schematic view of a fourth embodiment of the gearbox provided by the application;Figure 4 Enlarged view of the position of the oil inlet channel and the labyrinth oil channel.

[0031] The reference signs are explained as follows:

[0032] 10 box, 101 oil inlet channel;

[0033] 20 input structure;

[0034] 30 output structure;

[0035] 40 primary transmission gear train, 401 primary inner ring gear, 402 primary planet carrier, 403 primary sun gear, 404 primary planet gear, 405 primary planet gear shaft;

[0036] 50 secondary transmission gear train, 501 secondary inner ring gear, 502 secondary planet carrier, 5021 first labyrinth oil channel, 502a secondary planet carrier body, 502b secondary planet carrier split body, 503 secondary sun gear, 504 secondary planet gear, 505 secondary planet gear shaft;

[0037] 60 tertiary transmission gear train, 601 tertiary inner ring gear, 602 tertiary planet carrier, 6021 second labyrinth oil channel, 603 tertiary sun gear, 604 tertiary planet gear, 605 tertiary planet gear shaft;

[0038] 70 quaternary transmission gear train, 701 first spur gear, 702 second spur gear;

[0039] 80 connecting piece, 801 first connecting part, 802 second connecting part;

[0040] 90 first bearing; 100 second bearing; 110 third bearing. DETAILED DESCRIPTION

[0041] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application are further described in detail below in combination with the drawings and specific embodiments.

[0042] As shown in the drawings, the present application provides a gear box, which comprises a box 10, an input structure 20, an output structure 30, a primary transmission gear train 40, a secondary transmission gear train 50, a tertiary transmission gear train 60 and a quaternary transmission gear train 70. Figures 1-4 Among them, the input structure 20 and the output structure 30 are respectively arranged at the two axial ends of the gear box.

[0043] Among them, the primary transmission gear train 40, the secondary transmission gear train 50, the tertiary transmission gear train 60 and the quaternary transmission gear train 70 are sequentially arranged along the axial direction of the gear box.

[0044]

[0045] ​The first-stage transmission gear train 40 comprises a first-stage inner ring gear 401, a first-stage planet carrier 402, a first-stage sun gear 403 and a first-stage planet gear 404. The first-stage inner ring gear 401 is in transmission connection with the input structure 20. The first-stage planet carrier 402 is fixed to the box body 10. The first-stage planet gear 404 is engaged between the first-stage inner ring gear 401 and the first-stage sun gear 403.

[0046] The second-stage transmission gear train 50 comprises a second-stage inner ring gear 501, a second-stage planet carrier 502, a second-stage sun gear 503 and a second-stage planet gear 504. The second-stage inner ring gear 501 is in transmission connection with the first-stage sun gear 403. The second-stage planet carrier 502 is in transmission connection with the input structure 20. The second-stage planet gear 504 is engaged between the second-stage inner ring gear 501 and the second-stage sun gear 503.

[0047] The third-stage transmission gear train 60 comprises a third-stage inner ring gear 601, a third-stage planet carrier 602, a third-stage sun gear 603 and a third-stage planet gear 604. The third-stage inner ring gear 601 is fixed to the box body 10. The third-stage planet carrier 602 is in transmission connection with the second-stage sun gear 503. The third-stage planet gear 604 is engaged between the third-stage inner ring gear 601 and the third-stage sun gear 603.

[0048] The fourth-stage transmission gear train 70 comprises a first spur gear 701 and a second spur gear 702. The first spur gear 701 is in transmission connection with the third-stage sun gear 603. The second spur gear 702 is engaged with the first spur gear 701. The second spur gear 702 is in transmission connection with the output structure 30.

[0049] When the gear box works, the power input from the input structure 20 is divided into two paths. The first path is transmitted to the first-stage inner ring gear 401, the first-stage planet gear 404, the first-stage sun gear 403, the second-stage inner ring gear 501, the second-stage planet gear 504 and the second-stage sun gear 503 in sequence. The second path is transmitted to the second-stage planet carrier 502, the second-stage planet gear 504 and the second-stage sun gear 503 in sequence, so as to realize power split. Then the power is transmitted to the third-stage planet carrier 602, the third-stage planet gear 604 and the third-stage sun gear 603 in sequence from the second-stage sun gear 503. Then the power is transmitted to the first spur gear 701 and the second spur gear 702 in sequence from the third-stage sun gear 603. Finally, the power is output from the output structure 30.

[0050] Compared to tandem NGW planetary gearboxes, the aforementioned gearbox is more compact and smaller in size, and compared to three-stage enclosed planetary gearboxes, it offers a higher speed ratio. This gearbox balances small size and a high speed ratio, meeting the requirements of high-power wind turbine generators. For example, with eight first-stage planetary gears, six second-stage planetary gears, and four third-stage planetary gears, the gearbox achieves a speed ratio exceeding 260 (compared to lower ratios in previous gearboxes, which were generally below 240), a ratio sufficient for the needs of high-power wind turbine generators.

[0051] In one specific embodiment, the gearbox further includes a connector 80. The connector 80 is located near one end of the input structure 20 (e.g., Figures 1-4 The left end (located at position A) is connected to the first-stage sun gear 403 via a drum-shaped spline, allowing the first-stage sun gear 403 to float radially, thereby improving the gear meshing effect of the first-stage transmission gear train 40. The end of the connecting member 80 furthest from the input structure 20 (e.g., Figure 1 , Figure 2 The right end of the middle section (position indicated by B) is connected to the secondary internal gear ring 501 via a drum-shaped spline. Alternatively, the end of the connector 80 furthest from the input structure 20 (e.g., the end that is furthest from the input structure 20) is also connected. Figure 3 , Figure 4 The middle right end (position indicated by B) is fixed to the secondary internal gear ring 501. When the end of the connector 80 away from the input structure 20 is connected to the secondary internal gear ring 501 through a drum-shaped spline, the secondary internal gear ring 501 can float radially, thereby improving the gear meshing effect of the secondary transmission gear train 50.

[0052] Figures 1-3 In the middle, the connector 80 is an integral structure, and a region between the two ends of the connector 80 is supported on the first-stage planetary carrier 402 by the first bearing 90.

[0053] Figure 1 and Figure 2 In the middle, the end of the connecting part 80 away from the input structure 20 (the right end in the figure, the position indicated by B) is connected to the secondary internal gear ring 501 through a drum-shaped spline, so that the secondary internal gear ring 501 can float radially. This is beneficial to improving the gear meshing effect of the secondary transmission gear train 50 on the one hand, and can reduce the radial limiting performance requirements of the first bearing 90 on the other hand. Therefore, the first bearing 90 can be a sliding thrust bearing. The sliding thrust bearing is cheaper than the bearing with better radial limiting performance, thus reducing the cost of the gearbox. Specifically, two sliding thrust bearings can be set to restrict the bidirectional axial movement of the first connecting part 801 respectively.

[0054] and Figure 3In the embodiment shown in the drawings, the end of the connecting member 80 away from the input structure 20 (the right end in the drawings, the position indicated by B) is fixed to the second-class inner gear ring 501, so that the second-class inner gear 501 cannot float radially. In this case, the first bearing 90 needs to select a bearing with good radial limiting performance, such as a conical roller bearing.

[0055] Figure 4 In the embodiment shown in the drawings, the connecting member 80 is a split structure, including a first connecting part 801 and a second connecting part 802. The end of the second connecting part 802 close to the input structure 20 (the left end in the drawings, the position indicated by A) is connected to the first-class sun gear 403 through a drum spline. The end of the second connecting part 802 away from the input structure 20 (the right end in the drawings, the position indicated by C) is connected to the first end of the first connecting part 801 close to the input structure 20 through a drum spline. The end of the first connecting part 801 close to the input structure 20 is supported on the first-class planet carrier 402 through the first bearing 90. The end of the first connecting part 801 away from the input structure 20 (the right end in the drawings, the position indicated by B) is fixed to the second-class inner gear ring 501, so that the second-class inner gear 501 cannot float radially. In this case, the first bearing 90 needs to select a bearing with good radial limiting performance, such as a conical roller bearing. Compared with the embodiment shown in the drawings, the embodiment shown in the drawings has better support for the first-class sun gear 403. Figure 3

[0056] In a specific embodiment, the second-class sun gear 503 is connected to the third-class planet carrier 602 through a drum spline. In this way, the second-class sun gear 503 can float radially, thereby improving the gear meshing effect of the second-class transmission gear train 50.

[0057] Figure 1 In the embodiment shown in the drawings, the second-class sun gear 503 and the second-class inner gear ring 501 can both float radially, Figure 2 Figure 3 In the embodiment shown in the drawings, the second-class sun gear 503 can float radially, while the second-class inner gear ring 501 cannot float radially. Compared with the embodiment shown in the drawings, Figure 4 Figure 1 The gear meshing effect of the second-class transmission gear train 50 in the embodiment shown in the drawings is better than that in the embodiment shown in the drawings. Figure 2 Figure 3 Figure 4

[0058] In a specific embodiment, the first-class transmission gear train 40 includes a first-class planet shaft 405, both ends of the first-class planet shaft 405 are supported on the first-class planet carrier 402, and can be interference-fitted with the first-class planet carrier 402. The first-class planet gear 404 is sleeved on the outer periphery of the first-class planet shaft 405 through a bearing. In this design, the installation of the first-class planet gear 404 is realized by using a rigid pin structure. Compared with the flexible pin structure described in the background art, the rigid pin structure is easier to process and assemble, so it is beneficial to reduce the cost of the gear box.

[0059] ​​​​​​In one embodiment, the secondary transmission gear train 50 comprises a secondary planetary shaft 505, both ends of the secondary planetary shaft 505 are supported on the secondary planetary carrier 502, and can be in interference fit with the secondary planetary carrier 502, and the secondary planetary gear 504 is sleeved on the outer periphery of the secondary planetary shaft 505 through a bearing. In this way, the installation of the secondary planetary gear 504 is realized by using a rigid pin structure, which is easier to process and assemble than the flexible pin structure described in the background art, and thus is conducive to reducing the cost of the gear box.

[0060] In one embodiment, the tertiary transmission gear train 60 comprises a tertiary planetary shaft 605, both ends of the tertiary planetary shaft 605 are supported on the tertiary planetary carrier 602, and can be in interference fit with the tertiary planetary carrier 602, and the tertiary planetary gear 604 is sleeved on the outer periphery of the tertiary planetary shaft 605 through a bearing. In this way, the installation of the tertiary planetary gear 604 is realized by using a rigid pin structure, which is easier to process and assemble than the flexible pin structure described in the background art, and thus is conducive to reducing the cost of the gear box.

[0061] In one embodiment, for example Figures 1-4 , one end of the secondary planetary carrier 502 close to the input structure 20 is connected to the input structure 20 through a spline (indicated by position D in the figure), which can be a drum spline or a common spline. The other end of the secondary planetary carrier 502 away from the input structure 20 is supported on the box 10 through a second bearing 100. In this way, not only is the support of the secondary planetary carrier 502 realized, but also the connection position of the secondary planetary carrier 502 to the input structure 20 is far away from the gear meshing position of the secondary transmission gear train 50, resulting in that the runout of the input structure 20 is already very small (about 1 / 4-1 / 3 of the maximum runout of the input structure 20) when it is transmitted to the gear meshing position of the secondary transmission gear train 50, and thus the adverse effects of the input structure 20 on the gear meshing effect of the secondary transmission gear train 50 can be reduced.

[0062] In one embodiment, as shown in Figure 2 , the area between the two ends of the secondary planetary carrier 502 is supported on the tertiary planetary carrier 602 through a third bearing 110. In this way, the support effect of the secondary planetary carrier 502 can be further improved. Specifically, the third bearing 110 can be selected from cylindrical roller bearings, tapered roller bearings, or deep groove ball bearings.

[0063] In one embodiment, the spline is machined directly on the secondary planetary carrier 502. The secondary planetary carrier 502 can be made of castings to reduce costs.

[0064] In one embodiment, as shown in Figures 1-4As shown, the secondary planetary carrier 502 comprises a secondary planetary carrier body 502a and a secondary planetary carrier part 502b, and the secondary planetary carrier part 502b is machined with splines, and the secondary planetary carrier part 502b and the secondary planetary carrier body 502a are assembled together. The secondary planetary carrier body 502a can be a casting to reduce cost. The secondary planetary carrier part 502b can be a forging to ensure the strength of the splines.

[0065] In a specific embodiment, as shown in Figure 1 and Figure 2 , the assembly position (position E in the figure) of the secondary planetary carrier body 502a and the secondary planetary carrier part 502b is closer to the input structure 20 than the primary sun gear 403, Figure 1 and Figure 2 , the assembly position (position E in the figure) of the secondary planetary carrier body 502a and the secondary planetary carrier part 502b is on the left side of the primary sun gear 403.

[0066] In a specific embodiment, as shown in Figure 3 and Figure 4 , the assembly position (position E in the figure) of the secondary planetary carrier body 502a and the secondary planetary carrier part 502b is farther away from the input structure 20 than the primary sun gear 403, Figure 3 and Figure 4 , the assembly position (position E in the figure) of the secondary planetary carrier body 502a and the secondary planetary carrier part 502b is on the right side of the primary sun gear 403.

[0067] In a specific embodiment, as shown in Figure 5 , the secondary planetary carrier 502, the tertiary planetary carrier 602 and the box body 10 are respectively provided with a first oil passage 5021, a second oil passage 6021 and an oil inlet passage 101, the first oil passage 5021 communicates with the oil inlet passage 101 through the second oil passage 6021, and a labyrinth seal structure is arranged between the secondary planetary carrier 502 and the tertiary planetary carrier 602 to seal the communication between the second oil passage 6021 and the first oil passage 5021. In this way, more lubricating oil in the oil inlet passage 101 can be introduced into the secondary transmission gear train 50, avoiding the lubricating oil in the oil inlet passage 101 from flowing directly into the box body 10 without passing through the secondary transmission gear train 50, thereby improving the lubrication effect of the secondary transmission gear train 50. As shown in Figure 4 , the end of the secondary planetary carrier 502 close to the input structure 20 is connected to the input structure 20 through splines (position D in the figure), the end of the secondary planetary carrier 502 away from the input structure 20 is supported on the box body 10 through a second bearing 100, and the area between the two ends of the secondary planetary carrier 502 is not supported by a bearing. In this case, the labyrinth seal structure is arranged between the secondary planetary carrier 502 and the tertiary planetary carrier 602 to improve the lubrication effect of the secondary transmission gear train 50, and the effect is more obvious.

[0068] In a specific embodiment, a labyrinth seal structure is also arranged between the box 10 and the third planetary carrier 602, for sealing the communication between the oil inlet channel 101 and the second oil channel 6021, so as to avoid that the lubricating oil in the oil inlet channel 101 directly flows into the box 10 without passing through the third transmission gear train 60, thereby improving the lubricating effect of the third transmission gear train 60.

[0069] The above embodiments can be freely combined without conflict.

[0070] In addition, the application further provides a transmission device, which comprises a main shaft, a bearing seat sleeved on the outer periphery of the main shaft, and the gear box provided by any one of the above embodiments, wherein the input structure 20 of the gear box is fixedly connected with the main shaft, and the box 10 of the gear box is fixedly connected with the bearing seat.

[0071] The transmission device provided by the application has the beneficial effects of the gear box provided by any one of the above embodiments, and thus the beneficial effects of any one of the above embodiments are not repeated here.

[0072] In addition, the application further provides a wind turbine generator, which comprises the gear box provided by any one of the above embodiments or the transmission device.

[0073] The above describes the principles and implementation manners of the application by using specific examples, and the above embodiment descriptions are only used to help understand the method of the application and its core idea. It should be pointed out that, for those skilled in the art, without departing from the principles of the application, some improvements and modifications can be made to the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A gearbox, characterized in that, The gearbox includes a housing (10), an input structure (20), an output structure (30), a primary transmission gear train (40), a secondary transmission gear train (50), a tertiary transmission gear train (60), and a quaternary transmission gear train (70). The primary transmission gear train (40) includes a primary internal gear ring (401), a primary planetary carrier (402), a primary sun gear (403), and a primary planetary gear (404). The primary internal gear ring (401) is connected to the input structure (20) for transmission. The primary planetary carrier (402) is fixed to the housing (10). The primary planetary gear (404) meshes between the primary internal gear ring (401) and the primary sun gear (403). The secondary transmission gear train (50) includes a secondary internal gear ring (501), a secondary planetary carrier (502), a secondary sun gear (503), and a secondary planetary gear (504). The secondary internal gear ring (501) is connected to the primary sun gear (403) in a transmission connection. The secondary planetary carrier (502) is connected to the input structure (20) in a transmission connection. The secondary planetary gear (504) meshes between the secondary internal gear ring (501) and the secondary sun gear (503). The three-stage transmission gear train (60) includes a three-stage internal gear ring (601), a three-stage planetary carrier (602), a three-stage sun gear (603), and a three-stage planetary gear (604). The three-stage internal gear ring (601) is fixed to the housing (10), the three-stage planetary carrier (602) is connected to the two-stage sun gear (503) for transmission, and the three-stage planetary gear (604) meshes between the three-stage internal gear ring (601) and the three-stage sun gear (603). The four-stage transmission gear train (70) includes a first spur gear (701) and a second spur gear (702). The first spur gear (701) is connected to the third-stage sun gear (603) for transmission. The second spur gear (702) meshes with the first spur gear (701) and is connected to the output structure (30) for transmission.

2. The gearbox according to claim 1, characterized in that, The gearbox includes a connector (80), one end of which is close to the input structure (20) and connected to the first-stage sun gear (403) via a drum spline, and the other end of which is away from the input structure (20) and connected to the second-stage internal gear ring (501) via a drum spline or fixed to the second-stage internal gear ring (501).

3. The gearbox according to claim 2, characterized in that, An area between the two ends of the connector (80) is supported by the first bearing (90) on the first-stage planetary carrier (402).

4. The gearbox according to claim 3, characterized in that, The first bearing (90) is a sliding thrust bearing, which can limit the axial position of the first connecting part (801).

5. The gearbox according to claim 2, characterized in that, The connector (80) includes a first connecting part (801) and a second connecting part (802). The end of the first connecting part (801) near the input structure (20) is supported on the first-stage planetary carrier (402) by a first bearing (90). The end of the first connecting part (801) away from the input structure (20) is fixed to the second-stage internal gear ring (501). The end of the second connecting part (802) near the input structure (20) is connected to the first-stage sun gear (403) by a drum-shaped spline. The end of the second connecting part (802) away from the input structure (20) is connected to the end of the first connecting part (801) near the input structure (20) by a drum-shaped spline.

6. The gearbox according to any one of claims 1-5, characterized in that, The secondary sun gear (503) and the tertiary planetary carrier (602) are connected by a drum-shaped spline.

7. The gearbox according to any one of claims 1-5, characterized in that, The primary transmission gear train (40) includes a primary planetary gear shaft (405), both ends of which are supported by the primary planetary carrier (402), and the primary planetary gears (404) are sleeved on the outer circumference of the primary planetary gear shaft (405); and / or, The secondary transmission gear train (50) includes a secondary planetary gear shaft (505), both ends of which are supported by the secondary planetary carrier (502), and the secondary planetary gears (504) are sleeved on the outer circumference of the secondary planetary gear shaft (505); and / or, The three-stage transmission gear train (60) includes a three-stage planetary gear shaft (605), both ends of which are supported by the three-stage planetary carrier (602), and the three-stage planetary gears (604) are sleeved on the outer periphery of the three-stage planetary gear shaft (605).

8. The gearbox according to any one of claims 1-5, characterized in that, The end of the secondary planetary carrier (502) closest to the input structure (20) is connected to the input structure (20) via a spline, and the end of the secondary planetary carrier (502) furthest from the input structure (20) is supported on the housing (10) via a second bearing (100).

9. The gearbox according to claim 8, characterized in that, The area between the two ends of the secondary planetary carrier (502) is supported by the tertiary planetary carrier (602) by a third bearing (110).

10. The gearbox according to claim 8, characterized in that, Splines are machined on the secondary planetary carrier (502); or, the secondary planetary carrier (502) includes a secondary planetary carrier body (502a) and a secondary planetary carrier sub-body (502b), splines are machined on the secondary planetary carrier sub-body (502b), and the secondary planetary carrier sub-body (502b) and the secondary planetary carrier body (502a) are assembled together.

11. The gearbox according to claim 10, characterized in that, The secondary planetary carrier body (502a) is made of casting, and the secondary planetary carrier sub-body (502b) is made of forging.

12. The gearbox according to any one of claims 1-5, characterized in that, The secondary planetary carrier (502), the tertiary planetary carrier (602), and the housing (10) are respectively provided with a first labyrinth-type lubrication channel (5021), a second labyrinth-type lubrication channel (6021), and an oil inlet channel (1011). The first labyrinth-type lubrication channel (5021) is connected to the oil inlet channel (101) through the second labyrinth-type lubrication channel (6021).

13. A transmission device, characterized in that, The transmission device includes a main shaft, a bearing housing sleeved on the outer periphery of the main shaft, and a gearbox as described in any one of claims 1-12, wherein the input structure (20) of the gearbox is fixedly connected to the main shaft, and the housing (10) of the gearbox is fixedly connected to the bearing housing.

14. A wind turbine generator set, characterized in that, The wind turbine generator set includes a gearbox as described in any one of claims 1-12; or, the wind turbine generator set includes a transmission device as described in claim 13.

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