Gear box, transmission device and wind generating set

Abstract

The invention provides a gearbox, a transmission device and a wind generating set, the gearbox comprises a box body, an input structure, an output structure, a first-stage transmission wheel train, a second-stage transmission wheel train, a third-stage transmission wheel train and a fourth-stage transmission wheel train, a first-stage inner gear ring of the first-stage transmission wheel train is in transmission connection with the input structure, and a second-stage inner gear ring of the second-stage transmission wheel train is in transmission connection with the output structure; a second-stage inner gear ring of the second-stage transmission wheel train is in transmission connection with the first-stage sun gear, a second-stage planet carrier of the second-stage transmission wheel train is in transmission connection with the input structure, a third-stage planet carrier of the third-stage transmission wheel train is in transmission connection with the second-stage sun gear, the fourth-stage transmission wheel train comprises a first straight gear and a second straight gear, the first straight gear is in transmission connection with the third-stage sun gear, and the second straight gear is in transmission connection with the second-stage sun gear. The second straight gear is meshed with the first straight gear and is in transmission connection with the output structure. According to the gearbox, the small size and the large speed increasing ratio are both considered, and the use requirement of a high-power wind generating set for the gearbox is met.

Description

Technical Field

[0001] The present application relates to the technical field of gearboxes, and particularly to a gearbox, a transmission device, and a wind turbine generator set. Background Art

[0002] The core component of a wind turbine generator set is a gearbox. As wind turbine generator sets continue to develop towards high power, the requirements for the volume and speed ratio of the gearbox are getting higher and higher. For example, traditional three-stage enclosed planetary gearboxes and series-connected NGW-type planetary gearboxes can no longer meet the usage requirements of high-power wind turbine generator sets.

[0003] In addition, traditional planetary gearboxes mostly use flexible pin structures to install planetary gears. For example, in the gearbox disclosed in CN217713604U, a plurality of flexible pin structures are evenly distributed along the circumferential direction at the rear end of each planetary carrier. Each flexible pin structure is connected to the planetary carrier by interference fit, and the flexible pin structure includes an elastic pin bushing and an elastic pin. The elastic pin bushing is installed on the elastic pin by interference fit, and a planetary gear is installed on each flexible pin structure through a planetary gear rolling bearing. The flexible pin structure is complex, and the processing and assembly are difficult, resulting in a high cost of the gearbox.

[0004] In view of this, how to improve the gearbox is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] To solve the above technical problems, the present application provides a gearbox, which includes 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] Among them, the first-stage transmission gear train includes a first-stage internal gear ring, a first-stage planetary carrier, a first-stage sun gear, and first-stage planetary gears. The first-stage internal gear ring is in transmission connection with the input structure, the first-stage planetary carrier is fixed to the box body, and the first-stage planetary gears are meshed between the first-stage internal gear ring and the first-stage sun gear;

[0007] Among them, the second-stage transmission gear train includes a second-stage internal gear ring, a second-stage planetary carrier, a second-stage sun gear, and second-stage planetary gears. The second-stage internal gear ring 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 gears are meshed between the second-stage internal gear ring and the second-stage sun gear;

[0008] Among them, the third-stage transmission gear train includes a third-stage internal gear ring, a third-stage planetary carrier, a third-stage sun gear, and third-stage planetary gears. The third-stage internal gear ring is fixed to the housing, the third-stage planetary carrier is in transmission connection with the second-stage sun gear, and the third-stage planetary gears are meshed between the third-stage internal gear ring and the third-stage sun gear;

[0009] Among them, the third-stage transmission gear train includes a third-stage internal gear ring, a third-stage planetary carrier, a third-stage sun gear, and third-stage planetary gears. The third-stage internal gear ring is fixed to the housing, the third-stage planetary carrier is in transmission connection with the second-stage sun gear, and the third-stage planetary gears are meshed between the third-stage internal gear ring and the third-stage sun gear;

[0010] Among them, the four-stage transmission gear train includes a first spur gear and a second spur gear. The first spur gear is in transmission connection with the third-stage sun gear. The second spur gear meshes with the first spur gear, and the second spur gear is in transmission connection with the output structure.

[0011] An implementation of a gearbox, the gearbox includes a connecting piece. One end of the connecting piece close to the input structure is connected to the first-stage sun gear through a drum spline, and the end of the connecting piece far from the input structure is connected to the second-stage internal gear ring through a drum spline or fixed to the second-stage internal gear ring.

[0012] An implementation of a gearbox, a region between the two ends of the connecting piece is supported on the first-stage planet carrier through a first bearing.

[0013] An implementation of a gearbox, the first bearing is a sliding thrust bearing, and the sliding thrust bearing can limit the axial position of the first connecting portion.

[0014] An implementation of a gearbox, the connecting piece includes a first connecting portion and a second connecting portion. One end of the first connecting portion close to the input structure is supported on the first-stage planet carrier through a first bearing. The end of the first connecting portion far from the input structure is fixed to the second-stage internal gear ring. One end of the second connecting portion close to the input structure is connected to the first-stage sun gear through a drum spline, and the end of the second connecting portion far from the input structure is connected to the end of the first connecting portion close to the input structure through a drum spline.

[0015] An implementation of a gearbox, the second-stage sun gear is connected to the third-stage planet carrier through a drum spline.

[0016] An implementation of a gearbox, the first-stage transmission gear train includes a first-stage planet gear shaft. Both ends of the first-stage planet gear shaft are supported on the first-stage planet carrier, and the first-stage planet gear is sleeved on the outer periphery of the first-stage planet gear shaft; and / or,

[0017] The second-stage transmission gear train includes a second-stage planet gear shaft. Both ends of the second-stage planet gear shaft are supported on the second-stage planet carrier, and the second-stage planet gear is sleeved on the outer periphery of the second-stage planet gear shaft; and / or,

[0018] The third-stage transmission gear train includes a third-stage planet gear shaft. Both ends of the third-stage planet gear shaft are supported on the third-stage planet carrier, and the third-stage planet gear is sleeved on the outer periphery of the third-stage planet gear shaft.

[0019] An embodiment of the gearbox, one end of the secondary planet carrier close to the input structure is connected to the input structure through a spline, and the other end of the secondary planet carrier away from the input structure is supported on the housing through a second bearing.

[0020] An embodiment of the gearbox, the area between the two ends of the secondary planet carrier is supported on the tertiary planet carrier through a third bearing.

[0021] An embodiment of the gearbox, a spline is machined on the secondary planet carrier; alternatively, the secondary planet carrier includes a secondary planet carrier body and a secondary planet carrier split body, a spline is machined on the secondary planet carrier split body, and the secondary planet carrier split body and the secondary planet carrier body are assembled together.

[0022] An embodiment of the gearbox, the secondary planet carrier body is made of a casting, and the secondary planet carrier split body is made of a forging.

[0023] An embodiment of the gearbox, the secondary planet carrier, the tertiary planet carrier and the housing 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.

[0024] In addition, the present application also provides a transmission device, the transmission device includes a main shaft, a bearing housing sleeved on the outer periphery of the main shaft and the gearbox as described in any one of the above, the input structure of the gearbox is fixedly connected to the main shaft, and the housing of the gearbox is fixedly connected to the bearing housing.

[0025] In addition, the present application also provides a wind power generation set, the wind power generation set includes the gearbox as described in any one of the above; alternatively, the wind power generation set includes the above-mentioned transmission device.

[0026] The gearbox provided by the present application is more compact and smaller in volume compared with the series-connected NGW type planetary gear train gearbox, and has a larger speed ratio compared with the three-stage closed planetary gear train gearbox. The gearbox provided by the present application takes into account both small volume and large speed ratio, and meets the use requirements of high-power wind power generation sets for gearboxes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the first embodiment of the gearbox provided by the present application;

[0028] Figure 2 It is a schematic diagram of the second embodiment of the gearbox provided by the present application;

[0029] Figure 3 It is a schematic diagram of the third embodiment of the gearbox provided by the present application;

[0030] Figure 4 Schematic diagram of the fourth embodiment of the gearbox provided for this application;

[0031] Figure 5 is Figure 4 Enlarged view of the positions of the oil inlet passage and the labyrinth oil passage in

[0032] The reference numerals are explained as follows:

[0033] 10 housing, 101 oil inlet passage;

[0034] 20 input structure;

[0035] 30 output structure;

[0036] 40 first-stage transmission gear train, 401 first-stage internal gear ring, 402 first-stage planet carrier, 403 first-stage sun gear, 404 first-stage planet gear, 405 first-stage planet gear shaft;

[0037] 50 second-stage transmission gear train, 501 second-stage internal gear ring, 502 second-stage planet carrier, 5021 first labyrinth lubricating oil passage, 502a second-stage planet carrier body, 502b second-stage planet carrier split body, 503 second-stage sun gear, 504 second-stage planet gear, 505 second-stage planet gear shaft;

[0038] 60 third-stage transmission gear train, 601 third-stage internal gear ring, 602 third-stage planet carrier, 6021 second labyrinth lubricating oil passage, 603 third-stage sun gear, 604 third-stage planet gear, 605 third-stage planet gear shaft;

[0039] 70 fourth-stage transmission gear train, 701 first spur gear, 702 second spur gear;

[0040] 80 connecting piece, 801 first connecting part, 802 second connecting part;

[0041] 90 first bearing; 100 second bearing; 110 third bearing. Detailed implementation manners

[0042] In order to enable those skilled in the art of this technology to better understand the technical solution of this application, the technical solution of this application will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0043] As Figures 1-4 shown, this application provides a gearbox, which includes a box body 10, an input structure 20, an output structure 30, a first-stage transmission gear train 40, a second-stage transmission gear train 50, a third-stage transmission gear train 60, and a fourth-stage transmission gear train 70.

[0044] Among them, the input structure 20 and the output structure 30 are respectively arranged at the axial two ends of the gearbox.

[0045] Among them, the first-stage transmission gear train 40, the second-stage transmission gear train 50, the third-stage transmission gear train 60, and the fourth-stage transmission gear train 70 are arranged in sequence along the axial direction of the gearbox.

[0046] Among them, the first-stage transmission gear train 40 includes a first-stage internal gear ring 401, a first-stage planet carrier 402, a first-stage sun gear 403, and first-stage planet gears 404. The first-stage internal gear ring 401 is in transmission connection with the input structure 20. The first-stage planet carrier 402 is fixed to the housing 10. The first-stage planet gears 404 are meshed between the first-stage internal gear ring 401 and the first-stage sun gear 403.

[0047] Among them, the second-stage transmission gear train 50 includes a second-stage internal gear ring 501, a second-stage planet carrier 502, a second-stage sun gear 503, and second-stage planet gears 504. The second-stage internal gear ring 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 gears 504 are meshed between the second-stage internal gear ring 501 and the second-stage sun gear 503.

[0048] Among them, the third-stage transmission gear train 60 includes a third-stage internal gear ring 601, a third-stage planet carrier 602, a third-stage sun gear 603, and third-stage planet gears 604. The third-stage internal gear ring 601 is fixed to the housing 10. The third-stage planet carrier 602 is in transmission connection with the second-stage sun gear 503. The third-stage planet gears 604 are meshed between the third-stage internal gear ring 601 and the third-stage sun gear 603.

[0049] Among them, the fourth-stage transmission gear train 70 includes 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 meshed with the first spur gear 701. The second spur gear 702 is in transmission connection with the output structure 30.

[0050] When the above gearbox works, after the power is input from the input structure 20, it is divided into two paths. The first path is sequentially transmitted to the first-stage internal gear ring 401, the first-stage planet gears 404, the first-stage sun gear 403, the second-stage internal gear ring 501, the second-stage planet gears 504, and the second-stage sun gear 503. The second path is sequentially transmitted to the second-stage planet carrier 502, the second-stage planet gears 504, and the second-stage sun gear 503, thereby realizing power splitting. Then the power continues to be transmitted from the second-stage sun gear 503 to the third-stage planet carrier 602, the third-stage planet gears 604, and the third-stage sun gear 603 in sequence. Then the power continues to be transmitted from the third-stage sun gear 603 to the first spur gear 701 and the second spur gear 702 in sequence. Finally, the power is output from the output structure 30.

[0051] The above gearbox is more compact and smaller in volume compared to the series-connected NGW-type planetary gearbox, and has a larger speed ratio compared to the three-stage enclosed planetary gearbox. The above gearbox takes into account both small volume and large speed ratio, meeting the usage requirements of high-power wind turbines for the gearbox. For example, when the above gearbox is provided with 8 first-stage planetary gears, 6 second-stage planetary gears, and 4 third-stage planetary gears, the speed ratio can reach more than 260 (the speed ratios of previous gearboxes are generally below 240), and this speed ratio is sufficient to meet the usage requirements of high-power wind turbines.

[0052] In a specific embodiment, the gearbox further includes a connecting member 80. One end of the connecting member 80 close to the input structure 20 (for example Figures 1-4 the left end in the figure, the position indicated by A) is connected to the first-stage sun gear 403 through a drum spline, so that the first-stage sun gear 403 can radially float, thereby improving the gear meshing effect of the first-stage transmission gear train 40. One end of the connecting member 80 away from the input structure 20 (for example Figure 1 、 Figure 2 the right end in the figure, the position indicated by B) is connected to the second-stage internal gear ring 501 through a drum spline. Or one end of the connecting member 80 away from the input structure 20 (for example Figure 3 、 Figure 4 the right end in the figure, the position indicated by B) is fixed to the second-stage internal gear ring 501. When one end of the connecting member 80 away from the input structure 20 is connected to the second-stage internal gear ring 501 through a drum spline, the second-stage internal gear ring 501 can radially float, thereby improving the gear meshing effect of the second-stage transmission gear train 50.

[0053] Figures 1-3 In, the connecting member 80 is an integral structure, and a region between the two ends of the connecting member 80 is supported on the first-stage planetary carrier 402 through a first bearing 90.

[0054] Figure 1 and Figure 2 In, one end of the connecting member 80 away from the input structure 20 (the right end in the figure, the position indicated by B) is connected to the second-stage internal gear ring 501 through a drum spline, enabling the second-stage internal gear ring 501 to radially float. In this way, on the one hand, it is beneficial to improve the gear meshing effect of the second-stage transmission gear train 50, and on the other hand, the radial limiting performance requirements for the first bearing 90 can be reduced. Therefore, the first bearing 90 can be a sliding thrust bearing, and the sliding thrust bearing has a lower cost compared to bearings with better radial limiting performance. Therefore, the cost of the gearbox can be reduced. Specifically, two sliding thrust bearings can be provided to respectively limit the bidirectional axial movement of the first connecting portion 801.

[0055] While Figure 3In it, one end of the connecting member 80 away from the input structure 20 (the right end in the figure, the position indicated by B) is fixed to the secondary internal gear ring 501, so that the secondary internal gear 501 cannot float radially. In this case, the first bearing 90 needs to select a bearing with better radial limiting performance, such as a tapered roller bearing.

[0056] Figure 4 In it, the connecting member 80 is of a split structure, including a first connecting portion 801 and a second connecting portion 802. One end of the second connecting portion 802 close to the input structure 20 (the left end in the figure, the position indicated by A) is connected to the first-stage sun gear 403 through a drum spline. One end of the second connecting portion 802 away from the input structure 20 (the right end in the figure, the position indicated by C) is connected to one end of the first connecting portion 801 close to the input structure 20 through a drum spline. One end of the first connecting portion 801 close to the input structure 20 is supported on the first-stage planet carrier 402 through the first bearing 90. One end of the first connecting portion 801 away from the input structure 20 (the right end in the figure, the position indicated by B) is fixed to the secondary internal gear ring 501, so that the secondary internal gear 501 cannot float radially. In this case, the first bearing 90 needs to select a bearing with better radial limiting performance, such as a tapered roller bearing. Compared with Figure 3 the embodiment shown, this embodiment has better support for the first-stage sun gear 403.

[0057] In a specific embodiment, the secondary sun gear 503 is connected to the tertiary planet carrier 602 through a drum spline. In this way, the secondary sun gear 503 can float radially, thereby improving the gear meshing effect of the secondary transmission gear train 50.

[0058] Figure 1 and Figure 2 in it, both the secondary sun gear 503 and the secondary internal gear ring 501 can float radially, Figure 3 and Figure 4 in it, the secondary sun gear 503 can float radially while the secondary internal gear ring 501 cannot float radially. In comparison, Figure 1 and Figure 2 the gear meshing effect of the secondary transmission gear train 50 in Figure 3 and Figure 4 .

[0059] In a specific embodiment, the first-stage transmission gear train 40 includes a first-stage planet gear shaft 405. Both ends of the first-stage planet gear shaft 405 are supported on the first-stage planet carrier 402, and specifically can be in interference fit with the first-stage planet gear carrier 402. The first-stage planet gear 404 is sleeved on the outer periphery of the first-stage planet gear shaft 405 through a bearing. With such a design, the installation of the first-stage 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 machine and assemble, so it is beneficial to reduce the cost of the gearbox.

[0060] In a specific embodiment, the secondary transmission gear train 50 includes a secondary planetary gear shaft 505. Both ends of the secondary planetary gear shaft 505 are supported on the secondary planetary carrier 502, and specifically, it can be in interference fit with the secondary planetary carrier 502. The secondary planetary gear 504 is sleeved on the outer periphery of the secondary planetary gear shaft 505 through a bearing. With such a design, the installation of the secondary planetary gear 504 is achieved by using a rigid pin structure. Compared with the flexible pin structure described in the background art, the rigid pin structure is easier to machine and assemble, so it is beneficial to reduce the cost of the gearbox.

[0061] In a specific embodiment, the tertiary transmission gear train 60 includes a tertiary planetary gear shaft 605. Both ends of the tertiary planetary gear shaft 605 are supported on the tertiary planetary carrier 602, and specifically, it can be in interference fit with the tertiary planetary carrier 602. The tertiary planetary gear 604 is sleeved on the outer periphery of the tertiary planetary gear shaft 605 through a bearing. With such a design, the installation of the tertiary planetary gear 604 is achieved by using a rigid pin structure. Compared with the flexible pin structure described in the background art, the rigid pin structure is easier to machine and assemble, so it is beneficial to reduce the cost of the gearbox.

[0062] In a specific 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 (the position indicated by D in the figure), and the spline can be a drum spline or a common spline. The end of the secondary planetary carrier 502 far from the input structure 20 is supported on the housing 10 through a second bearing 100. With such a design, not only the support of the secondary planetary carrier 502 is realized, but also the connection position between the secondary planetary carrier 502 and the input structure 20 is far from the gear meshing position of the secondary transmission gear train 50. When the runout of the input structure 20 is transmitted to the gear meshing position of the secondary transmission gear train 50, it has become very small (about 1 / 4 - 1 / 3 of the maximum runout of the input structure 20). Therefore, it can reduce the adverse effect of the input structure 20 on the gear meshing effect of the secondary transmission gear train 50.

[0063] In a specific embodiment, as Figure 2 shown, 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. With such a design, the support effect of the secondary planetary carrier 502 can be further improved. Specifically, the third bearing 110 can be selected from a cylindrical roller bearing, a tapered roller bearing or a deep groove ball bearing.

[0064] In a specific embodiment, a spline is directly machined on the secondary planetary carrier 502. The secondary planetary carrier 502 can be made of a casting to facilitate cost reduction.

[0065] In a specific embodiment, as Figures 1-4As shown, the secondary planet carrier 502 includes a secondary planet carrier body 502a and a secondary planet carrier split body 502b. A spline is machined on the secondary planet carrier split body 502b, and the secondary planet carrier split body 502b and the secondary planet carrier body 502a are assembled together. The secondary planet carrier body 502a can be made of a casting to facilitate cost reduction. The secondary planet carrier split body 502b can be made of a forging to facilitate ensuring the spline strength.

[0066] In a specific embodiment, as Figure 1 and Figure 2 shown, the assembly position of the secondary planet carrier body 502a and the secondary planet carrier split body 502b (the position indicated by E in the figure) is closer to the input structure 20 than the first sun gear 403. Figure 1 and Figure 2 In, the assembly position of the secondary planet carrier body 502a and the secondary planet carrier split body 502b (the position indicated by E in the figure) is located on the left side of the first sun gear 403.

[0067] In a specific embodiment, as Figure 3 and Figure 4 shown, the assembly position of the secondary planet carrier body 502a and the secondary planet carrier split body 502b (the position indicated by E in the figure) is farther from the input structure 20 than the first sun gear 403. Figure 3 and Figure 4 In, the assembly position of the secondary planet carrier body 502a and the secondary planet carrier split body 502b (the position indicated by E in the figure) is located on the right side of the first sun gear 403.

[0068] In a specific embodiment, as Figure 5 shown, the secondary planet carrier 502, the tertiary planet carrier 602, and the housing 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 is communicated with the oil inlet passage 101 through the second oil passage 6021. A labyrinth seal structure is arranged between the secondary planet carrier 502 and the tertiary planet carrier 602 for sealing the communication part between the second oil passage 6021 and the first oil passage 5021. With such a design, 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 flowing directly into the interior of the housing 10 without passing through the secondary transmission gear train 50, thereby improving the lubrication effect of the secondary transmission gear train 50. As Figure 4 shown, one end of the secondary planet carrier 502 close to the input structure 20 is connected to the input structure 20 through a spline (the position indicated by D in the figure), and the other end of the secondary planet carrier 502 far from the input structure 20 is supported by the housing 10 through a second bearing 100, and there is no bearing support in the area between the two ends of the secondary planet carrier 502. In this case, setting the above-mentioned labyrinth seal structure between the secondary planet carrier 502 and the tertiary planet carrier 602 has a more obvious effect of improving the lubrication effect of the secondary transmission gear train 50.

[0069] In a specific embodiment, a labyrinth seal structure is also provided between the housing 10 and the third-stage planetary carrier 602 to seal the connection between the oil inlet passage 101 and the second oil passage 6021, preventing the lubricating oil in the oil inlet passage 101 from flowing directly into the interior of the housing 10 without passing through the third-stage transmission gear train 60, thereby improving the lubrication effect of the third-stage transmission gear train 60.

[0070] The above embodiments can be freely combined without conflict.

[0071] In addition, the present application also provides a transmission device, which includes a main shaft, a bearing housing sleeved on the outer periphery of the main shaft, and the gearbox provided in any of the above embodiments. 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.

[0072] The transmission device provided by the present application has the beneficial effects of any of the above embodiments due to having the gearbox provided in any of the above embodiments, and will not be elaborated herein.

[0073] In addition, the present application also provides a wind power generating set, which includes the gearbox provided in any of the above embodiments or the above transmission device.

[0074] The principles and implementation manners of the present application have been described by applying specific examples above. The description of the above embodiments is only used to help understand the method and its core idea of the present application. It should be noted that for those of ordinary skill in the art in the technical field of the present application, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. Gearbox, characterized in that, the gearbox includes a housing (10), an input structure (20), an output structure (30), a first-stage transmission gear train (40), a second-stage transmission gear train (50), a third-stage transmission gear train (60) and a fourth-stage transmission gear train (70); wherein, the first-stage transmission gear train (40) includes a first-stage internal gear ring (401), a first-stage planet carrier (402), a first-stage sun gear (403) and first-stage planet gears (404), the first-stage internal gear ring (401) is in transmission connection with the input structure (20), the first-stage planet carrier (402) is fixed to the housing (10), and the first-stage planet gears (404) are meshed between the first-stage internal gear ring (401) and the first-stage sun gear (403); wherein, the second-stage transmission gear train (50) includes a second-stage internal gear ring (501), a second-stage planet carrier (502), a second-stage sun gear (503) and second-stage planet gears (504), the second-stage internal gear ring (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), and the second-stage planet gears (504) are meshed between the second-stage internal gear ring (501) and the second-stage sun gear (503); wherein, the third-stage transmission gear train (60) includes a third-stage internal gear ring (601), a third-stage planet carrier (602), a third-stage sun gear (603) and third-stage planet gears (604), the third-stage internal gear ring (601) is fixed to the housing (10), the third-stage planet carrier (602) is in transmission connection with the second-stage sun gear (503), and the third-stage planet gears (604) are meshed between the third-stage internal gear ring (601) and the third-stage sun gear (603); wherein, the fourth-stage transmission gear train (70) includes 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 meshed with the first spur gear (701), and the second spur gear (702) is in transmission connection with the output structure (30).

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

3. The gearbox according to claim 2, characterized in that, a region between the two ends of the connecting member (80) is supported on the first-stage planet carrier (402) through a first bearing (90).

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

5. The gearbox according to claim 2, characterized in that, The connecting member (80) includes a first connecting portion (801) and a second connecting portion (802). One end of the first connecting portion (801) close to the input structure (20) is supported on the first-stage planet carrier (402) through a first bearing (90). One end of the first connecting portion (801) away from the input structure (20) is fixed to the second-stage internal gear ring (501). One end of the second connecting portion (802) close to the input structure (20) is connected to the first-stage sun gear (403) through a drum spline. One end of the second connecting portion (802) away from the input structure (20) is connected to one end of the first connecting portion (801) close to the input structure (20) through a drum spline.

6. The gearbox according to any one of claims 1-5, characterized in that, the second-stage sun gear (503) is connected to the third-stage planet carrier (602) through a drum spline.

7. The gearbox according to any one of claims 1-5, characterized in that, the first-stage transmission gear train (40) includes a first-stage planet gear shaft (405). Both ends of the first-stage planet gear shaft (405) are supported on the first-stage planet carrier (402). The first-stage planet gear (404) is sleeved on the outer periphery of the first-stage planet gear shaft (405); and / or, the second-stage transmission gear train (50) includes a second-stage planet gear shaft (505). Both ends of the second-stage planet gear shaft (505) are supported on the second-stage planet carrier (502). The second-stage planet gear (504) is sleeved on the outer periphery of the second-stage planet gear shaft (505); and / or, the third-stage transmission gear train (60) includes a third-stage planet gear shaft (605). Both ends of the third-stage planet gear shaft (605) are supported on the third-stage planet carrier (602). The third-stage planet gear (604) is sleeved on the outer periphery of the third-stage planet gear shaft (605).

8. The gearbox according to any one of claims 1-5, characterized in that, one end of the second-stage planet carrier (502) close to the input structure (20) is connected to the input structure (20) through a spline. One end of the second-stage planet carrier (502) away from the input structure (20) is supported on the housing (10) through a second bearing (100).

9. The gearbox according to claim 8, characterized in that, the region between both ends of the second-stage planet carrier (502) is supported on the third-stage planet carrier (602) through a third bearing (110).

10. The gearbox according to claim 8, characterized in that, a spline is machined on the second-stage planet carrier (502); or, the second-stage planet carrier (502) includes a second-stage planet carrier body (502a) and a second-stage planet carrier split body (502b). A spline is machined on the second-stage planet carrier split body (502b). The second-stage planet carrier split body (502b) and the second-stage planet carrier body (502a) are assembled together.

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

12. The gearbox according to any one of claims 1-5, characterized in that the secondary planet carrier (502), the tertiary planet carrier (602) and the housing (10) are respectively provided with a first labyrinth lubricating oil passage (5021), a second labyrinth lubricating oil passage (6021) and an oil inlet passage (1011), and the first labyrinth lubricating oil passage (5021) is communicated with the oil inlet passage (101) through the second labyrinth lubricating oil passage (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 the gearbox according to any one of claims 1-12. 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 power generating set, characterized in that the wind power generating set includes the gearbox according to any one of claims 1-12; alternatively, the wind power generating set includes the transmission device according to claim 13.

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