Double-nut structure for bearing pre-tightening and flange fixing of input shaft of speed reducer

Abstract

A double-nut structure for bearing pre-tightening and flange fixing of an input shaft of a speed reducer relates to the technical field of mechanical transmission systems and comprises a conical transmission support, a gear shaft and a conical roller bearing arranged between the conical transmission support and the gear shaft. A gear is arranged at the end, located in the box body, of the gear shaft, and a front bearing, a supporting sleeve, a rear bearing, a locking nut and a flange are sequentially arranged at the other end, provided with the gear, of the gear shaft. The front bearing and the rear bearing are arranged in a seat hole of the cone transmission support, and an adjusting gasket I used for compensating the bearing clearance is arranged between the front bearing and the supporting sleeve. The locking nut is in threaded fit with the gear shaft to apply pre-tightening force to the bearing, the flange is fixedly connected with the gear shaft in the circumferential direction through a spline, and the flange is in threaded fit with the gear shaft through the insert nut to be pressed on the end face of the locking nut. The technical problems that an existing structure is poor in bearing pre-tightening effect, prone to loosening, difficult to adjust, complex in sealing structure and difficult to maintain can be solved.

Description

Technical Field

[0001] This invention relates to the field of mechanical transmission system technology, specifically a double-nut structure for bearing preload and flange fixing of a reducer input shaft. Background Technology

[0002] In recent years, with the rapid development of high-horsepower, heavy-duty tractors, the average working time of these machines has reached over 1500 hours, placing increasingly stringent quality requirements on the front drive axle. The main reducer assembly is the core of power transmission in the tractor's front drive axle, transmitting high torque and withstanding high-frequency vibrations. Therefore, the requirements for the bearing preload accuracy, support rigidity, locking reliability, and sealing performance of the input shaft are becoming increasingly stringent, directly affecting the overall transmission performance, service life, and reliability of the machine.

[0003] The existing technology uses a single nut to preload the shaft system via a flange, which has the following drawbacks: 1) The tractor's front drive shaft is directly connected to the flange, making it difficult to achieve perfect concentricity. The flange is constantly subjected to high-frequency centrifugal force, which directly affects the preload of the front and rear bearings of the main reducer assembly, resulting in a non-ideal preload condition for the bearings; 2) Under alternating loads and thermal deformation, the single nut preload is prone to loosening, leading to increased axial clearance and reduced shaft rigidity and precision; 3) Preload adjustment via a flange is difficult, requiring extremely large locking torque that is not easily controlled precisely. Excessive preload can lead to high temperatures, while insufficient preload can cause abnormal noise and wear; 4) The sealing structure is cumbersome, the assembly process is demanding and difficult to control, and there is a high risk of oil leakage later; 5) The maintainability for adjustment and replacement is poor. Summary of the Invention

[0004] The purpose of this invention is to provide a double-nut structure for bearing preload and flange fixing of a reducer input shaft, which can solve the technical problems of poor bearing preload, easy loosening, difficult adjustment, complex sealing structure, and difficult maintenance of existing structures.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A double-nut structure for bearing preload and flange fixing of a reducer input shaft includes a tapered drive support, a gear shaft, and a tapered roller bearing disposed between the tapered drive support and the gear shaft. A locking nut for applying preload to the bearing and a flange for external connection are coaxially disposed on the gear shaft.

[0007] The gear shaft has a gear at one end inside the housing, and a front bearing, a support sleeve, a rear bearing, a lock nut, and a flange are sequentially arranged on the other end of the gear shaft leading to the gear.

[0008] The front and rear bearings are located in the seat holes of the bevel drive support and are used to rotate the gear shaft on the bevel drive support. An adjusting shim I is provided between the front bearing and the support sleeve to compensate for bearing clearance.

[0009] The locking nut and gear shaft apply preload to the bearing through a threaded connection. The flange and gear shaft are circumferentially fixedly connected by a spline. The flange is pressed against the end face of the locking nut by the threaded connection between the insert nut and the gear shaft.

[0010] Furthermore, an adjusting shim II is provided between the front bearing and the gear to adjust the position of the gear.

[0011] Furthermore, a flat washer is provided between the lock nut and the rear bearing, and a sealing ring is provided between the lock nut and the gear shaft to provide a sealing function.

[0012] Furthermore, the locking nut is provided with a thin ring portion that can be plastically deformed, and the gear shaft is provided with a groove at a position corresponding to the thin ring portion. The thin ring portion can be plastically deformed and embedded into the groove to achieve mechanical anti-loosening between the locking nut and the gear shaft.

[0013] Furthermore, a heavy-duty washer is provided between the insert nut and the flange, and the insert nut presses the flange against the end face of the lock nut through the heavy-duty washer.

[0014] Furthermore, an oil seal is provided in the seat hole of the cone drive support, and the lip of the oil seal slides with the cylindrical surface of the locking nut to achieve a sealing effect.

[0015] Furthermore, the end face of the locking nut is provided with multiple tool holes for applying torque to the locking nut using appropriate tools to achieve preload on the bearing.

[0016] Furthermore, the flange has a recess to conceal and accommodate the insert nut.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects: 1. The adjusting shim I and the support sleeve are pressed together between the front and rear bearings. The preload is completely eliminated by the lock nut without over-preloading, which improves the radial and axial support stiffness of the drive gear shaft. 2. The flange is pressed onto the end face of the locking nut by the insert nut. A huge static friction force is generated between the end face of the flange and the end face of the locking nut, forming a double nut effect, which achieves reliable axial fixation, effectively offsets the effects of vibration and thermal deformation, and keeps the bearing in the best working condition for a long time. 3. The flange does not participate in the bearing pre-tightening process, has no additional stress interference, and effectively prevents loosening, ensuring reliable and stable power transmission; 4. The locking nut and the drive gear shaft adopt a locking edge design to achieve mechanical locking and prevent loosening; 5. A small annular gap is left between the outer diameter of the shoulder of the locking nut and the seat hole of the tapered drive support, which can prevent the entry of large particles of foreign matter, play an effective dust prevention role, and improve the long-term sealing performance. 6. The two nuts are tightened separately, separating the "precision adjustment" and "spring-loaded fixation" functions, greatly improving the convenience of maintenance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the overall structure of the locking nut in this invention.

[0020] Figure descriptions: 1. Conical drive support; 11. Seat hole; 12. Oil seal; 13. Elastic retaining ring; 2. Gear shaft; 21. Gear; 22. Groove; 3. Bearing; 31. Front bearing; 32. Rear bearing; 33. Support sleeve; 34. Adjusting shim I; 35. Adjusting shim II; 36. Flat washer ring; 4. Locking nut; 41. Sealing ring; 42. Thin ring portion; 43. Tool hole; 44. Shoulder; 45. Finished area; 5. Flange; 51. Insert nut; 52. Heavy-duty washer ring; 53. Recessed portion. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the features and performance of a double-nut structure for bearing preload and flange fixing of a reducer input shaft in the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] Please see the appendix Figures 1-2 A double-nut structure for bearing preload and flange fixing of a reducer input shaft includes a tapered drive support 1, a gear shaft 2, and a tapered roller bearing 3 disposed between the tapered drive support 1 and the gear shaft 2. A locking nut 4 for applying preload to the bearing 3 and a flange 5 for external connection are coaxially disposed on the gear shaft 2.

[0023] The gear shaft 2 has a gear 21 at one end inside the housing, and a front bearing 31, a support sleeve 33, a rear bearing 32, a lock nut 4, and a flange 5 are sequentially arranged on the other end of the gear shaft 2 with the gear 21.

[0024] The front bearing 31 and the rear bearing 32 are installed in the seat hole 11 of the bevel transmission support 1 to rotate the gear shaft 2 on the bevel transmission support 1. An adjusting shim I 34 is provided between the front bearing 31 and the support sleeve 33 to compensate for the clearance of the bearing 3. An adjusting shim II 35 is provided between the front bearing 31 and the gear 21 to adjust the position of the gear 21.

[0025] The locking nut 4 and the gear shaft 2 are threaded together to apply preload to the bearing 3. The end face of the locking nut 4 is provided with multiple tool holes 43, which are used to apply torque to the locking nut 4 using appropriate tools to achieve preload on the bearing 3. The number of tool holes 43 is set according to the specific tools used. As a preferred option, this solution uses four tool holes 43 evenly distributed around the circumference.

[0026] The locking nut 4 has a thin ring portion 42 that can be plastically deformed, and the gear shaft 2 has a groove 22 at a position corresponding to the thin ring portion. The thin ring portion 42 can be plastically deformed and embedded into the groove 22 to achieve mechanical anti-loosening between the locking nut 4 and the gear shaft 2. The number of grooves 22 is specifically determined according to the diameter of the gear shaft, and should usually be more than 2. As a preferred option, this solution uses 4 grooves 22 evenly distributed around the circumference.

[0027] A flat washer 36 is provided between the locking nut 4 and the rear bearing 32, and a sealing ring 41 is provided between the locking nut 4 and the gear shaft 2 for sealing purposes. The type of sealing ring is selected according to specific requirements; as a preferred option, an O-ring is used in this scheme. The inner hole of the locking nut 4 near the flat washer 36 and the gear shaft 2 adopt a transition fit to ensure coaxiality, and the contact surface of the transition fit needs to be finely ground. The end face of the locking nut 4 in contact with the flat washer 36 is finely ground, and the sealing ring 41 is located at this end face, and the surface of the annular groove accommodating the sealing ring 41 needs to be finely ground. Both ends of the flat washer 36 are finely ground. The finely ground section of the gear shaft 2, the flat washer 36, and the annular groove of the locking nut 4 together form the enclosure of the sealing ring 41. The gear shaft 2, the locking nut 4, the flat washer 36, and the sealing ring 41 rotate synchronously during operation, forming a static seal, which together provides a reliable radial and end face seal.

[0028] The locking nut 4 is also provided with a shoulder 44, and a small annular gap is left between the outer diameter of the shoulder 44 and the seat hole 11 to prevent the entry of large particles of foreign matter.

[0029] Flange 5 and gear shaft 2 are circumferentially fixedly connected by a spline. Flange 5 is pressed against the end face of lock nut 4 by the threaded engagement of insert nut 51 and gear shaft 2, forming a double-nut locking effect. Specifically, a heavy-duty washer 52 is provided between insert nut 51 and flange 5, and insert nut 51 presses flange 5 against end face of lock nut 4 through heavy-duty washer 52. Flange 5 has a recess 53 to hide and accommodate insert nut 51.

[0030] An oil seal 12 is provided in the seat hole 11 of the cone drive support 1. The lip of the oil seal 12 slides with the cylindrical surface of the locking nut 4 to achieve a sealing effect. An elastic retaining ring 13 is provided in the seat hole 11 to limit the axial position of the oil seal 12 in the seat hole 11. The part of the locking nut 4 that contacts the lip of the oil seal 12 has a precision-machined area 45. The precision-machined area 45 needs to be heat-treated and precision-ground to ensure a precise fit with the oil seal 12 and extend its service life.

[0031] In specific implementation, the preload of bearing 3 and the fixing of flange 5 adopt a double nut structure, including gear shaft 2, adjusting shim II 35, front bearing 31, adjusting shim I 34, support sleeve 33, rear bearing 32, flat washer ring 36, locking nut 4, flange 5, heavy-duty washer ring 52 and insert nut 51.

[0032] The gear shaft 2 is assembled in the seat hole 11 of the bevel transmission support 1 through the bearing 3, and the adjusting shim I 34 and the support sleeve 33 are pressed between the front bearing 31 and the rear bearing 32.

[0033] The locking nut 4 is tightened onto the gear shaft 2, pre-tightening the front bearing 31 and the rear bearing 32. The locking nut 4, the flat washer 36, the gear shaft 2, and the sealing ring 41 together form a static seal. The locking nut 4 and the lip of the oil seal 12 form a rotary seal.

[0034] Flange 5 is connected to gear shaft 2 via spline connection, and insert nut 51 presses flange 5 against the end face of lock nut 4.

[0035] The diameter of the seat hole 11 of the cone drive support 1 is 1mm larger than the diameter of the shoulder 44 of the locking nut 4, which is used to prevent the entry of large particles and foreign objects, and plays an effective role in dust prevention.

[0036] The end face of flange 5 near the locking nut 4 is pressed and fitted against the corresponding end face of locking nut 4. The end face of flange 5 near insert nut 51 is higher than the end face of gear shaft 2 to ensure the compression of flange 5.

[0037] Adjusting shims I 34 are available in two thicknesses: 0.5mm and 0.1mm. Adjusting shims II 35 are available in four thicknesses: 0.3mm, 2.0mm, 2.1mm, and 2.2mm. The locking nut 4 has a thin ring 42, and the gear shaft 2 has a groove 22 for mechanical locking and preventing loosening after assembly.

[0038] During assembly, the outer rings of the front bearing 31 and the rear bearing 32 are simultaneously pressed onto the corresponding seat holes 11 of the tapered drive support 1. Then, the inner ring of the rear bearing 32 is placed on its outer ring, and the elastic retaining ring 13 is installed and the oil seal 12 is pressed onto it.

[0039] Based on the actual mounting distance of gear shaft 2 provided by the supplier, select an adjusting shim II 35 of appropriate thickness to ensure that the gear pair is in the appropriate contact position. Place the adjusting shim II 35 and the inner ring of the front bearing 31 onto gear shaft 2 in sequence.

[0040] First, select and adjust shim I34, then install it and support sleeve 33 onto gear shaft 2 in sequence. Then, place gear shaft 2 with inner ring of front bearing 31 and support sleeve 33 into seat hole 11 of bevel transmission support 1. At the same time, press inner ring of front bearing 31 and inner ring of rear bearing 32 into place, and gently tap the end face of gear shaft 2 to disengage inner and outer ring of front bearing 31 to prevent "false preload".

[0041] Fit the flat washer 36 onto the gear shaft 2, and use a tool to tighten the lock nut 4 to a standard torque of 250 to 270 N·m. Apply preload to the bearing 3 and measure the idle torque of the shaft system to be between 1 and 1.5 N·m.

[0042] Assemble flange 5 and observe to confirm that the end face of flange 5 is higher than the end face of gear shaft 2. Then, put heavy-duty washer 52 on gear shaft 2 and tighten insert nut 51 with a standard torque of 270-300 N·m.

[0043] In this embodiment, to ensure the sealing reliability of the sealing ring 41, the roughness of the end face of the flat washer ring 36 is controlled between Ra0.4 and Ra0.8, the roughness of the end face of the locking nut 4 is controlled between Ra1.6 and Ra3.2, the roughness of the mating surface at the transition fit between the locking nut 4 and the gear shaft 2 is controlled between Ra0.8 and Ra1.6, and the surface roughness of the annular groove on the locking nut 4 used to accommodate the sealing ring 41 on the shoulder mating surface of the gear shaft 2 is controlled between Ra0.4 and Ra0.8.

[0044] In this scheme, the locking nut 4 is tightened on the gear shaft 2 to pre-tighten the bearing 3, and the flange 5 does not participate in the pre-tightening process of the bearing 3.

[0045] In this design, the locking nut 4 is designed with a thin ring 42 and the gear shaft 2 is designed with a groove 22. After pre-tightening, the thin ring 42 of the locking nut 4 and the groove 22 are pressed into the groove 22 of the gear shaft 2 to achieve mechanical locking and anti-loosening.

[0046] In this design, the diameter of the seat hole 11 of the cone drive support 1 is 1 mm larger than the diameter of the shoulder 44 of the locking nut 4. When the gear shaft 2 is working, the gap between the two will not cause interference, and can also block large particles of foreign matter from the outside, thus forming the first dust barrier.

[0047] In this scheme, after the locking nut 4 is tightened, according to the dimensional chain, the end face of the flange 5 is at least 1.5mm higher than the end face of the gear shaft 2, thereby ensuring the compression of the flange 5.

[0048] In this design, the end face of flange 5 near the locking nut is pressed against the corresponding end face of locking nut 4, forming a double nut structure. The huge friction force effectively prevents locking nut 4 from loosening, ensuring the reliability of the system.

[0049] With this solution, the locking nut 4 directly provides the preload force to the bearing, allowing for high-precision control of the bearing 3's preload. The compressed support sleeve 33 improves the system's radial and axial stiffness. The insert nut 51 withstands and compensates for the vibration and thermal deformation of the gear shaft 2, and forms a double-nut effect with the locking nut 4 through the flange 5. Simultaneously, the locking nut 4 is locked onto the gear shaft 2, forming a mechanical safety barrier against loosening, significantly reducing the risk of the locking nut 4 coming loose and improving the reliability of the shaft system. The dustproof design of the shaft shoulder 44 of the locking nut 4 and the seat hole 11 of the tapered drive support 1 acts as a dust barrier, preventing the entry of large particles and increasing the service life of the oil seal 12, resulting in a longer-lasting seal. Separating the "precision adjustment" and "elastic fixation" functions makes assembly processability and market maintenance more convenient.

[0050] It should be noted that the parts not described in detail in this solution are all prior art. The above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A double-nut structure for bearing preload and flange fixing of a reducer input shaft, comprising a tapered drive support (1), a gear shaft (2), and a tapered roller bearing (3) disposed between the tapered drive support (1) and the gear shaft (2), characterized in that: The gear shaft (2) is coaxially provided with a locking nut (4) for applying preload to the bearing (3) and a flange (5) for connecting to the outside. The gear shaft (2) is located at one end of the housing and has a gear (21). The other end of the gear shaft (2) with the gear (21) is provided with a front bearing (31), a support sleeve (33), a rear bearing (32), a lock nut (4), and a flange (5). The front bearing (31) and the rear bearing (32) are located in the seat hole (11) of the cone drive support (1) for rotating the gear shaft (2) on the cone drive support (1). An adjusting shim I (34) is provided between the front bearing (31) and the support sleeve (33) to compensate for the clearance of the bearing (3). The locking nut (4) and the gear shaft (2) apply a preload to the bearing (3) through a threaded connection. The flange (5) and the gear shaft (2) are circumferentially fixedly connected by a spline. The flange (5) is pressed against the end face of the locking nut (4) by the threaded connection between the insert nut (51) and the gear shaft (2).

2. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: An adjusting shim II (35) is provided between the front bearing (31) and the gear (21) to adjust the position of the gear (21).

3. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: A flat washer (36) is provided between the locking nut (4) and the rear bearing (32), and a sealing ring (41) is provided between the locking nut (4) and the gear shaft (2) to provide a sealing function.

4. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: The locking nut (4) is provided with a thin ring (42) that can be plastically deformed. The gear shaft (2) is provided with a groove (22) at the position corresponding to the thin ring. The thin ring (42) can be embedded into the groove (22) through plastic deformation to achieve mechanical anti-loosening of the locking nut (4) and the gear shaft (2).

5. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: A heavy-duty washer (52) is provided between the insert nut (51) and the flange (5). The insert nut (51) presses the flange (5) against the end face of the lock nut (4) through the heavy-duty washer (52).

6. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: An oil seal (12) is provided in the seat hole (11) of the cone drive support (1). The lip of the oil seal (12) slides with the cylindrical surface of the locking nut (4) to achieve a sealing effect.

7. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: The end face of the locking nut (4) is provided with multiple tool holes (43) for applying torque to the locking nut (4) using corresponding tools to achieve pre-tightening of the bearing (3).

8. The double-nut structure for bearing preload and flange fixing of a reducer input shaft as described in claim 1, characterized in that: The flange (5) has a recess (53) for concealing and accommodating the insert nut (51).

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