Bicycle rear wheel hub

Abstract

The utility model provides a bicycle rear wheel hub which comprises a middle shaft, a hub shell and a tower footing, the hub shell and the tower footing are rotatably arranged on the middle shaft, the middle shaft is further provided with a rotating driving ratchet wheel and a rotating clutch ratchet wheel, a first bearing is arranged between the hub shell and the middle shaft, a first spline is arranged on the periphery of the driving ratchet wheel, and a second spline is arranged on the periphery of the clutch ratchet wheel. A first spline groove is formed in the inner circumferential face of a center hole of the hub shell. Or, a first spline groove is formed in the periphery of the driving ratchet wheel, a first spline is arranged on the inner circumferential face of the middle hole of the hub shell, and the first spline penetrates into the first spline groove; the end face, deviating from the clutch ratchet, of the driving ratchet is provided with a containing groove matched with the first bearing in size. Through spline fit between the driving ratchet wheel and the hub shell, the concentricity problem caused by traditional threaded connection is avoided, the containing groove is formed in the end face of the driving ratchet wheel, the first bearing can be partially or completely embedded, the bearing installation position deviates towards the tower footing side (namely, the bearing installation position is far away from the center of a center shaft), and therefore stress is dispersed, and concentrated abrasion of the first bearing is reduced.

Description

Technical Field

[0001] This utility model relates to the field of bicycle hub technology, and in particular to a bicycle rear wheel hub. Background Technology

[0002] Bicycle wheels typically consist of a hub assembly. The hub assembly is located at the center of the bicycle wheel. A traditional bicycle hub assembly includes a hub axle (bottom bracket), hub body, bearing unit, ratchet mechanism, and locking mechanism. The hub axle is mounted to the bicycle frame. The hub body is rotatably supported around the hub axle via the bearing unit. The bearing unit is positioned between the hub axle and the hub body. The ratchet mechanism is used to synchronize the rotation of the hub body with the freehub base during pedaling.

[0003] Existing hubs, due to the installation of sprockets and freehub bodies, have a location where the drive ratchet and other components are installed close to the center of the hub shaft. Consequently, the bearing installed between the hub bore and the drive ratchet end face is also close to the center of the hub shaft. This causes the bearing installed at this location to become the main load-bearing bearing, resulting in greater wear compared to bearings in other locations during use, thus shortening the overall lifespan of the hub, as shown in patent document CN108437699B. To address this, a solution was developed that incorporates a groove in the drive ratchet to partially accommodate the bearing. This allows the bearing to be positioned closer to the center of the hub than a further away location, as shown in patent document CN216467162U. In this design, the hub housing and drive ratchet are connected by a threaded lock. However, this method makes it extremely difficult to ensure the concentricity of the bearings on both sides of the hub. Furthermore, after prolonged use, if the bearing is damaged, it is difficult to remove the threaded drive ratchet (because the locking direction of the thread is the same as the driving direction). Since the thread always has a certain angle, it is difficult to ensure that the bearing rests perfectly on a horizontal plane after final installation. To ensure smooth contact between the bearing and the hub housing and the hub (as coaxial as possible with the hub), the depth of the groove is limited to ensure that most of the bearing surface contacts the hub housing (to counteract the angular offset caused by the threaded drive ratchet). Therefore, the distance the bearing is offset from the center is also limited, and the effect of reducing bearing wear is not very good. Otherwise, the angle between the bearing axis and the hub axis would increase, which would actually increase wear. Utility Model Content

[0004] To address the aforementioned problems, the purpose of this utility model is to provide a bicycle rear wheel hub.

[0005] This utility model is implemented using the following method: A bicycle rear wheel hub includes a bottom bracket, a hub housing, and a freehub base. The hub housing and freehub base are rotatably mounted on the bottom bracket. The bottom bracket also has a rotating drive ratchet and a clutch ratchet. The opposing surfaces of the drive ratchet and the clutch ratchet have mutually cooperating ratchet teeth. A first bearing is provided between the hub housing and the bottom bracket. The central hole of the hub housing has a first bearing mounting section on the side near the freehub base. The outer periphery of the drive ratchet has a first spline, and the inner circumferential surface of the first bearing mounting section of the central hole of the hub housing has a first spline groove; or, the outer periphery of the drive ratchet has a first spline groove, and the inner circumferential surface of the first bearing mounting section of the central hole of the hub housing has a first spline, with the first spline passing through the first spline groove; the end face of the drive ratchet away from the clutch ratchet has a receiving groove matching the size of the first bearing, and the first bearing is partially or entirely located in the receiving groove; the clutch ratchet is circumferentially limited and connected to the freehub base.

[0006] Preferably, the first spline is composed of multiple key bodies, which are spaced apart and arranged around the outer peripheral surface of the drive ratchet. Similarly, the first spline groove is also composed of multiple grooves spaced apart in an annular manner on the inner peripheral surface of the first bearing mounting section.

[0007] Preferably, all the key bodies protrude from the end opposite to the clutch ratchet, and the space formed by the protruding portions of all the key bodies constitutes the receiving groove. The outer peripheral surface of the first bearing contacts the inner peripheral surface of the bearing mounting section, and at the same time contacts the inner peripheral surfaces of the multiple key bodies.

[0008] Preferably, the first spline is composed of multiple key bodies, which are spaced around the inner circumferential surface of the first bearing mounting section. Similarly, the first spline groove is also composed of multiple grooves spaced around the outer circumferential surface of the drive ratchet.

[0009] Preferably, the circumferential surface of the receiving groove is connected to the inner surface of the plurality of grooves respectively, and the end face of the groove adjacent to the clutch ratchet is spaced apart from the end face of the drive ratchet facing the clutch ratchet. The outer circumferential surface of the first bearing contacts the inner circumferential surface of the bearing mounting section and the inner circumferential surface of the key, and at the same time contacts the inner circumferential surface of the receiving groove.

[0010] Preferably, the outer peripheral surface of the clutch ratchet is provided with a second spline, and the inner peripheral surface of the inner peripheral side of the hub base near the section of the hub housing is provided with a second spline groove, and the second spline passes into the second spline groove.

[0011] Preferably, the tower base is further provided with a spring, one end of which abuts against the end face of the clutch ratchet away from the drive ratchet, and the other end of the spring is axially limited and connected to the tower base for pushing the clutch ratchet toward the drive ratchet.

[0012] Preferably, the clutch ratchet has a receiving groove on its end face away from the drive ratchet, and one end of the spring extends into the receiving groove and abuts against the inner end face of the receiving groove.

[0013] Preferably, a plurality of second bearings are provided between the central shaft and the freehub base, and a bearing spacer is provided between adjacent second bearings on the central shaft. A bearing spacer is also provided between the second bearing on the central shaft located near the hub housing and the first bearing. A stop ring is provided at the end of the central shaft located on the drive ratchet of the first bearing away from the freehub base to abut against the inner ring of the first bearing. The first bearing mounting section of the hub housing abuts against the outer ring of the first bearing. The other end of the spring abuts against the end face of the second bearing in the freehub base near the hub housing. A sealing ring metal ring and a sealing ring rubber are connected between the opposite end faces of the freehub base and the hub housing. Both ends of the central shaft are provided with end caps. The end cap at one end abuts against the side of the freehub base away from the hub housing, and the end cap at the other end abuts against the side of the hub housing away from the freehub base.

[0014] Preferably, the hub housing has a convex ring surrounding the central shaft on the side facing away from the hub base, and a third spline is provided on the outer circumferential surface of the convex ring for circumferentially limiting the connection to the disc brake.

[0015] The beneficial effects of this utility model are as follows: This utility model provides a bicycle rear wheel hub, which, compared with the prior art, has at least the following technical effects: 1. By using the splined fit (first spline and first spline groove) between the drive ratchet and the hub housing, the concentricity problem caused by traditional threaded connections is avoided. The axial guiding nature of the spline ensures the coaxiality of the bearing during installation, allowing the receiving groove to be machined deeper. Directly machined spline bases allow for more precise control of accuracy, and are more practical and effective in extending bearing life. A receiving groove is provided on the end face of the drive ratchet, allowing the first bearing to be partially or completely embedded, shifting the bearing installation position towards the freehub base side (i.e., away from the center of the bottom bracket), thereby dispersing the force and reducing concentrated wear of the first bearing. 2. The fit between multiple spaced keys and grooves improves the uniform force distribution of the spline connection, reduces the risk of local stress concentration, enhances the torque transmission stability between the hub housing and the drive ratchet, and maintains lightweight design. 3. The circumference of the receiving groove is composed of multiple key bodies, or the inner side of the keyway is connected to the circumference of the receiving groove. This ensures the contact area between the bearing's outer circumference and the hub housing while further increasing the depth of the receiving groove. This allows the first bearing to be installed more into the drive ratchet, further increasing the distance between the first bearing and the center of the shaft, thus reducing stress. Furthermore, this semi-open spline ring formed by the dispersed keyways and key bodies allows for the creation of thicker and wider keyways and key bodies during machining, increasing the contact area between the drive ratchet and the hub housing during operation and improving drive efficiency. Therefore, from the perspectives of machining difficulty, product precision, and user experience, the semi-enclosed spline connection is superior to existing threaded connections on the market in improving the hub's durability and smoothness. 4. By using the spline engagement between the clutch ratchet and the freehub base, traditional threaded or pin connections are replaced, enabling quick assembly and disassembly while ensuring immediate responsiveness in power transmission. 5. Continuous axial thrust is applied by the spring to ensure tight engagement between the clutch ratchet and the drive ratchet, preventing slippage during pedaling. 6. Embedding the spring end into the receiving groove of the clutch ratchet avoids spring misalignment, improves the consistency of thrust direction, and enhances system reliability. It also helps reduce the axial space occupied by the freehub, clutch ratchet, and spring on the bottom bracket, further assisting the first bearing in moving away from the center of the bottom bracket and further reducing the stress on the first bearing. 7. Spacers separate adjacent bearings, precisely controlling bearing spacing and optimizing load distribution; the sealing ring combination: a metal ring provides rigid support, and a rubber ring provides elastic sealing, balancing dustproof, waterproof, and durable properties. 8. A dedicated spline interface at the end of the hub housing enables quick installation and precise alignment of the disc brake disc. Attached Figure Description

[0016] Figure 1 This is an exploded view of a bicycle rear wheel hub according to this utility model.

[0017] Figure 2 This is a sectional view of a component of a bicycle rear wheel hub according to the present invention.

[0018] Figure 3 This is a cross-sectional structural diagram of a bicycle rear wheel hub according to the present invention.

[0019] Figure 4 This is a schematic diagram showing the assembly of the hub housing, the first bearing, and the drive ratchet of this utility model.

[0020] Figure 5 This is a schematic cross-sectional view of the hub housing, the first bearing, and the drive ratchet of this utility model after assembly.

[0021] Figure 6 This is an assembly diagram of the drive ratchet and the first bearing.

[0022] Figure 7 This is a schematic diagram of the structure of a bicycle rear wheel hub that can be fitted with a disc brake disc.

[0023] Figure 8 This is a cross-sectional view of a bicycle rear wheel hub that can be fitted with a disc brake.

[0024] Explanation of reference numerals: 1. Bottom bracket; 2. Hub housing; 21. First spline groove; 22. Third spline; 3. Freeloader base; 31. Second spline groove; 4. Drive ratchet; 41. First spline; 42. Receiving groove; 5. Clutch ratchet; 51. Second spline; 52. Receiving groove; 6. First bearing; 7. Spring; 8. Second bearing; 9. Bearing spacer; 10. Sealing ring metal ring; 11. Sealing ring rubber; 12. End cap. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Please see Figures 1 to 8A bicycle rear wheel hub, usable with V-brakes or disc brakes, includes a bottom bracket 1, a hub housing 2, and a freehub base 3. The hub housing 2 and freehub base 3 are rotatably mounted on the bottom bracket 1. The bottom bracket 1 also has a rotating drive ratchet 4 and a clutch ratchet 5. The opposing surfaces of the drive ratchet 4 and the clutch ratchet 5 have mating ratchet teeth. A first bearing 6 is provided between the hub housing 2 and the bottom bracket 1. The central hole of the hub housing 2 has a first bearing mounting section on the side near the freehub base 3. The outer periphery of the drive ratchet 4 has a first spline 41. The inner circumferential surface of the first bearing mounting section of the central hole of body 2 is provided with a first spline groove 21; or, the outer circumference of the drive ratchet 4 is provided with a first spline groove 21, and the inner circumferential surface of the first bearing mounting section of the central hole of the hub housing 2 is provided with a first spline 41, the first spline 41 passing into the first spline groove 21; the end face of the drive ratchet 4 facing away from the clutch ratchet 5 is provided with a receiving groove 42 that matches the size of the first bearing 6, and the first bearing 6 is partially or entirely located in the receiving groove 42; the clutch ratchet 5 is circumferentially limited and connected to the base 3. By using the splined engagement (first spline 41 and first spline groove 21) between the drive ratchet 4 and the hub housing 2, the concentricity problem caused by traditional threaded connections is avoided. The axial guidance of the spline ensures the coaxiality of the bearing during installation. The directly machined spline base allows for more precise control of accuracy, which is more practical and effective in extending the bearing life. A receiving groove 42 is provided on the end face of the drive ratchet 4, allowing the first bearing 6 to be partially or completely embedded, shifting the bearing installation position towards the base 3 (i.e., away from the center of the central shaft 1), thereby distributing the force and reducing concentrated wear on the first bearing 6. This allows the depth of the receiving groove 42 to be increased from 3mm to at least 8mm, further significantly reducing the concentrated force on the first bearing 6.

[0027] Please see Figures 1 to 8 Preferably, the inner end face of the receiving groove 42 also has a secondary sink groove, which makes way for the inner ring end face of the first bearing 6, so that the receiving groove 42 only contacts the outer ring of the first bearing 6.

[0028] Please see Figures 1 to 8 Preferably, the first spline 41 is composed of multiple key bodies, which are spaced apart and arranged around the outer peripheral surface of the drive ratchet 4. Similarly, the first spline groove 21 is also composed of multiple grooves spaced apart annularly on the inner peripheral surface of the first bearing mounting section. The multiple spaced key bodies and grooves cooperate to improve the uniform force distribution of the spline connection, reduce the risk of localized stress concentration, enhance the torque transmission stability between the hub housing 2 and the drive ratchet 4, and maintain a lightweight design.

[0029] Please see Figures 1 to 8Preferably, all the key bodies protrude from the end opposite to the clutch ratchet 5, and the space formed by the protruding parts of all the key bodies constitutes the receiving groove 42. The outer peripheral surface of the first bearing 6 contacts the inner peripheral surface of the bearing mounting section, and at the same time contacts the inner peripheral surfaces of multiple key bodies. The peripheral surface of the receiving groove 42 is formed by multiple key bodies, which can ensure the contact area between the outer peripheral surface of the bearing and the hub housing 2, while further increasing the depth of the receiving groove 42 so that more of the first bearing 6 can be installed in the drive ratchet 4, further increasing the distance of the first bearing 6 from the center of the central shaft 1, and further reducing the force. Moreover, the semi-open spline ring formed by the dispersed keyways and key bodies can form keyways and key bodies with greater thickness and width during processing, increasing the contact area between the drive ratchet 4 and the hub housing 2 during driving, which helps to improve driving efficiency. Therefore, whether from the perspective of processing difficulty, product precision, or user experience, the semi-enclosed spline connection is superior to the existing threaded connection methods on the market in terms of improving the durability and smoothness of the hub.

[0030] Please see Figures 1 to 8 Preferably, the first spline 41 is composed of multiple key bodies, which are spaced apart and arranged around the inner circumferential surface of the first bearing mounting section. Similarly, the first spline groove 21 is also composed of multiple grooves spaced apart annularly on the outer circumferential surface of the drive ratchet 4. The multiple spaced key bodies and grooves cooperate to improve the uniform force distribution of the spline connection, reduce the risk of localized stress concentration, enhance the torque transmission stability between the hub housing 2 and the drive ratchet 4, and maintain a lightweight design.

[0031] Please see Figures 1 to 8 Preferably, the circumferential surface of the receiving groove 42 is connected to the inner surface of the plurality of grooves respectively, and the end face of the groove adjacent to the clutch ratchet 5 is spaced from the end face of the drive ratchet 4 facing the clutch ratchet 5. The outer circumferential surface of the first bearing 6 contacts the inner circumferential surface of the bearing mounting section and the inner circumferential surface of the key body, and at the same time contacts the inner circumferential surface of the receiving groove 42. The inner surface of the keyway is connected to the circumferential surface of the receiving groove 42, which ensures the contact area between the bearing's outer circumference and the hub housing 2, while further increasing the depth of the receiving groove 42. This allows more of the first bearing 6 to be installed in the drive ratchet 4, further increasing the distance between the first bearing 6 and the center of the central shaft 1, and further reducing the stress. Furthermore, this semi-open spline ring formed by the dispersed keyways and keys allows for the creation of keyways and keys with greater thickness and width during machining, increasing the contact area between the drive ratchet 4 and the hub housing 2 during operation, thus improving driving efficiency. Therefore, from the perspectives of machining difficulty, product precision, and user experience, the semi-enclosed spline connection is superior to existing threaded connections on the market in improving the durability and smoothness of the hub. The groove extends through both ends of the drive ratchet 4.

[0032] Please see Figures 1 to 3 , Figure 8 Preferably, the outer circumferential surface of the clutch ratchet 5 is provided with a second spline 51, and the inner circumferential surface of the freehub base 3 near the hub housing 2 is provided with a second spline groove 31, with the second spline 51 inserted into the second spline groove 31. The spline engagement between the clutch ratchet 5 and the freehub base 3 replaces the traditional threaded or pin connection method, enabling quick assembly and disassembly while ensuring immediate responsiveness of power transmission. It also better meets the coaxiality requirements of the clutch ratchet and the bottom bracket, reducing wear on the clutch ratchet 5 and the drive ratchet 4.

[0033] Please see Figures 1 to 3 , Figure 8 Preferably, the base 3 is further provided with a spring 7. One end of the spring 7 abuts against the end face of the clutch ratchet 5 away from the drive ratchet 4, and the other end of the spring 7 is axially limited and connected to the base 3, used to push the clutch ratchet 5 towards the drive ratchet 4. By continuously applying axial thrust through the spring 7, it is ensured that the teeth of the clutch ratchet 5 and the drive ratchet 4 are tightly engaged, preventing slippage when stepping on.

[0034] Please see Figures 1 to 3 , Figure 8 Preferably, the clutch ratchet 5 has a receiving groove 52 on its end face opposite to the drive ratchet 4, and one end of the spring 7 extends into the receiving groove 52 and abuts against the inner end face of the receiving groove 52. Embedding the end of the spring 7 into the receiving groove 52 of the clutch ratchet 5 can, on the one hand, prevent the spring 7 from deflecting, improve the consistency of the thrust direction, and enhance the reliability of the system; on the other hand, it can also help reduce the axial space occupied by the tower base 3, clutch ratchet 5, and spring 7 on the central shaft 1, and can further help the first bearing 6 move away from the middle position of the central shaft 1, further reducing the force on the first bearing 6.

[0035] Please see Figures 1 to 3 , Figure 8Preferably, a plurality of second bearings 8 are provided between the central shaft 1 and the freehub base 3, and a bearing spacer 9 is provided between adjacent second bearings 8 on the central shaft 1. A bearing spacer 9 is also provided between the second bearing 8 on the central shaft 1 located near the hub housing 2 and the first bearing 6. A stop ring is provided at the end of the central shaft 1 where the first bearing 6 is away from the freehub base 3 to abut against the inner ring of the first bearing 6. The first bearing mounting section of the hub housing 2 abuts against the outer ring of the first bearing 6. The other end of the spring 7 abuts against the end face of the second bearing 8 on the freehub base 3 near the hub housing 2. A sealing ring metal ring 10 and a sealing ring rubber 11 are connected between the opposite end faces of the freehub base 3 and the hub housing 2. Both ends of the central shaft 1 are provided with end caps 12. The end cap 12 at one end abuts against the side of the freehub base 3 away from the hub housing 2, and the end cap 12 at the other end abuts against the side of the hub housing 2 away from the freehub base 3. By separating adjacent bearings with spacers, the bearing spacing is precisely controlled, and the load distribution is optimized; the sealing ring combination: the metal ring provides rigid support, and the rubber ring achieves elastic sealing, taking into account both dustproof and waterproof properties as well as durability.

[0036] Please see Figure 7 , Figure 8 Preferably, the hub housing 2 has a convex ring surrounding the central shaft 1 on the end face opposite to the freehub base 3, and a third spline 22 is provided on the outer circumferential surface of the convex ring for circumferential positioning and connection of the disc brake. The dedicated spline interface at the end of the hub housing 2 enables quick installation and precise alignment of the disc brake disc.

[0037] The working principle of this utility model is as follows:

[0038] The drive ratchet 4 and the central hole of the hub housing 2 are connected by the first spline 41 and the first spline groove, avoiding the concentricity problem caused by traditional threaded connections. Therefore, the first bearing 6 will not have an axial angular deviation when installed in the receiving groove 42, and the depth of the receiving groove 42 can be increased with confidence for easy disassembly and maintenance. The drive ratchet 4 is provided with a receiving groove 42 surrounded by multiple spaced keys, forming a semi-enclosed structure for the first bearing 6. This ensures that the part of the first bearing 6 inserted into the receiving groove 42 can still contact the inner circumferential surface of the central hole of the hub housing 2 (ensuring the corrective effect of the central hole on the installation deviation of the first bearing 6). Increasing the depth of the receiving groove 42 allows more of the first bearing 6 to be installed in the drive ratchet 4, further increasing the distance between the first bearing 6 and the center of the central shaft 1, further reducing the force and distributing it to the remaining second bearings 8, which can improve the overall service life of the hub. The semi-open spline ring formed by the dispersed keyways and key bodies can form keyways and bodies with greater thickness and width during processing, increasing the contact surface between the drive ratchet 4 and the hub housing 2 during driving (the area of ​​each key body facing the direction of rotation is significantly increased when pushed, and the area of ​​the push surface of the groove body is also significantly increased), which helps to improve driving efficiency.

[0039] During operation, the pedal generates driving force, which is transmitted to the freehub base 3 via the chain and chainring. The freehub base 3 then transmits the force to the clutch ratchet 5 via the second spline 51 and the second spline groove 31. The clutch ratchet 5 then transmits the force to the drive ratchet 4 via the ratchet teeth (the clutch ratchet 5 is kept in contact with the drive ratchet 4 by the axial thrust of the spring 7). The drive ratchet 4 then transmits the force to the hub housing 2 via the first spline 41 and the first spline groove 21. When the pedal does not provide driving force and generates resistance, the freehub base 3 provides a reverse rotational force to the clutch ratchet 5. The ratchet teeth on the drive ratchet 4 cannot provide a reverse circumferential limit, so the drive ratchet 4 and the clutch ratchet 5 will rotate relative to each other. The ratchet teeth on the drive ratchet 4 push the ratchet teeth on the clutch ratchet 5, causing the clutch ratchet 5 to overcome the axial force of the spring 7 and move away from the drive ratchet 4, thus achieving power cut-off.

[0040] Several points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection" and "linkage" should be interpreted broadly, and can be mechanical or electrical connection, or internal connection between two components, or direct connection. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may change.

[0041] Secondly: The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

[0042] Finally, the above description is only a preferred embodiment of the present utility model. The protection scope of the present utility model is not limited to the above embodiments. All technical solutions that fall within the scope of the present utility model are protected by the present utility model.

[0043] It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of this utility model should also be considered within the scope of protection of this utility model.

Claims

1. A bicycle rear wheel hub, comprising a hub axle, a hub shell and a tower, the hub shell and the tower being rotatably arranged on the hub axle, a driving ratchet and a clutch ratchet being rotatably arranged on the hub axle, the driving ratchet and the clutch ratchet being provided with mutually matching ratchets on opposite surfaces, a first bearing being arranged between the hub shell and the hub axle, characterized in that: The hub housing has a first bearing mounting section on the side of the central hole near the freehub base. The outer periphery of the drive ratchet has a first spline, and the inner circumferential surface of the first bearing mounting section of the central hole of the hub housing has a first spline groove; or, the outer periphery of the drive ratchet has a first spline groove, and the inner circumferential surface of the first bearing mounting section of the central hole of the hub housing has a first spline, with the first spline passing through the first spline groove; the end face of the drive ratchet opposite to the clutch ratchet has a receiving groove matching the size of the first bearing, and the first bearing is partially or completely located in the receiving groove; the clutch ratchet is circumferentially limited and connected to the freehub base.

2. A bicycle rear wheel hub as defined in claim 1, characterized in that: The first spline is composed of multiple key bodies, which are spaced around the outer circumferential surface of the drive ratchet. Similarly, the first spline groove is also composed of multiple grooves spaced around the inner circumferential surface of the first bearing mounting section.

3. A bicycle rear wheel hub as defined in claim 2, characterized in that: Each key protrudes from the end opposite to the clutch ratchet, and the space formed by the protruding parts of all the keys constitutes the receiving groove. The outer peripheral surface of the first bearing contacts the inner peripheral surface of the bearing mounting section, and at the same time contacts the inner peripheral surfaces of the multiple keys.

4. The bicycle rear wheel hub as defined in claim 1, wherein: The first spline is composed of multiple key bodies, which are spaced around the inner circumferential surface of the first bearing mounting section. Similarly, the first spline groove is also composed of multiple grooves spaced around the outer circumferential surface of the drive ratchet.

5. A bicycle rear wheel hub as defined in claim 4, characterized in that: The circumferential surface of the receiving groove is connected to the inner surface of the plurality of grooves respectively. The end face of the groove adjacent to the clutch ratchet is spaced apart from the end face of the drive ratchet facing the clutch ratchet. The outer circumferential surface of the first bearing contacts the inner circumferential surface of the bearing mounting section and the inner circumferential surface of the key body, and at the same time contacts the inner circumferential surface of the receiving groove.

6. The bicycle rear wheel hub as defined in claim 1, wherein: The outer peripheral surface of the clutch ratchet is provided with a second spline, and the inner peripheral surface of the inner peripheral side of the hub base near the section of the hub housing is provided with a second spline groove, and the second spline passes into the second spline groove.

7. The bicycle rear wheel hub as defined in claim 1, wherein: The tower base is also provided with a spring. One end of the spring abuts against the end face of the clutch ratchet that is away from the drive ratchet, and the other end of the spring is axially limited and connected to the tower base to push the clutch ratchet toward the drive ratchet.

8. A bicycle rear wheel hub as defined in claim 7, characterized in that: The clutch ratchet has a receiving groove on its end face away from the drive ratchet, and one end of the spring extends into the receiving groove and abuts against the inner end face of the receiving groove.

9. A bicycle rear wheel hub as defined in claim 7, characterized in that: Multiple second bearings are provided between the central shaft and the freehub base. Bearing spacers are provided between adjacent second bearings on the central shaft. Bearing spacers are also provided between the second bearing on the central shaft located near the hub housing and the first bearing. A stop ring is provided at the end of the central shaft where the first bearing is away from the freehub base, to abut against the inner ring of the first bearing. The first bearing mounting section of the hub housing abuts against the outer ring of the first bearing. The other end of the spring abuts against the end face of the second bearing in the freehub base near the hub housing. A sealing ring metal ring and a sealing ring rubber are connected between the opposite end faces of the freehub base and the hub housing. End caps are provided at both ends of the central shaft. The end cap at one end abuts against the side of the freehub base away from the hub housing, and the end cap at the other end abuts against the side of the hub housing away from the freehub base.

10. The bicycle rear wheel hub as defined in claim 1, wherein: The hub housing has a convex ring around the central shaft on the side facing away from the hub base, and a third spline is provided on the outer circumferential surface of the convex ring for circumferentially limiting the connection to the disc brake.

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