Variable-speed hub

Abstract

A variable-speed hub, comprising: a hub shell; a first-stage driving assembly, which directly drives the hub shell by means of a first pawl; and a second-stage driving assembly, which is connected to the first-stage driving assembly by means of a planetary gearset. The second-stage driving assembly comprises: a second clutch, which is fixed to the hub shell and rotates along with the hub shell; and a second spline, which is configured to drive the hub shell, wherein the second clutch comprises a second pawl for coupling or decoupling a power transmission relationship between the second spline and the hub shell according to the rotational speed of the hub shell, and the second pawl is arranged on an outer peripheral side of the second spline. The variable-speed hub can avoid the problems of a user pedaling without resistance and it not being possible to shift gears due to pawls being damaged.

Description

A speed-changing hub Technical Field

[0001] The invention belongs to the field of riding vehicles, and in particular relates to an improvement on a speed-changing hub. Background Art

[0002] Bicycles and electric vehicles are currently equipped with automatic speed-shifting features. This is achieved by installing an automatic speed-shifting hub, whose power input is connected to the flywheel of a bicycle or the motor output shaft of an electric vehicle to provide power. The hub automatically changes the gear ratio between the input and output ends based on the input speed, automatically adjusting the speed of the bicycle or electric vehicle to the speed, thereby achieving high speed and low energy consumption. This hub is widely praised for its convenient, hands-free riding experience.

[0003] Shifting hub speeds is typically achieved through a built-in one-, two-, or three-stage power take-off. Typically, a first-stage PTO directly drives the hub shell, a second-stage PTO increases the speed via a planetary gear set, and a third-stage PTO increases the speed of the second-stage PTO by a planetary gear set before driving the hub shell.

[0004] There are two problems in the existing technology: 1. The coupling or decoupling of the power transmission relationship between the clutch device and the hub shell is driven by the rotational force input from the power end. When the user stops pedaling and enters the coasting state, when the user intervenes in pedaling again, in order to achieve the state of coupling between the clutch and the hub shell, the user needs to pedal under low resistance to reach the gear corresponding to the corresponding speed. Pedaling under low resistance gives the user a short and fast feeling of "stepping on air", which makes the riding experience poor.

[0005] 2. In existing clutches, the pawl is located inside the spline. When the speed reaches the corresponding gear, the pawl engages the spline. Due to the small internal radius of the spline, the corresponding pawl's lever arm is smaller. This results in greater torque on the end face where the pawl and spline meet, which can cause increased stress on the pawl itself or lead to the pawl shaft becoming stuck, preventing upshifts or downshifts. Furthermore, when the pawl is located inside the spline, the clutch structure and assembly process become more complex.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to provide a speed-changing hub which can prevent a user from stepping on empty space, is not easily damaged by claws and ratchets, avoids jamming, and has a simplified structure.

[0008] Specifically, the present invention provides a speed-changing hub, comprising:

[0009] hub shell;

[0010] A first-stage drive assembly directly drives the hub shell via a first pawl;

[0011] A second-stage drive assembly is connected to the first-stage drive assembly via a planetary gear set;

[0012] The second stage drive assembly includes a second clutch fixed to the hub shell and rotating with the hub shell, and a second spline for driving the hub shell;

[0013] The second clutch includes a second pawl that couples or decouples the power transmission relationship between the second spline and the hub shell according to the rotation speed of the hub shell;

[0014] The second pawl is provided on the outer peripheral side of the second spline.

[0015] In a preferred embodiment of the present invention, the second spline includes an external spline, and the second pawl is coupled to or decoupled from a plurality of key portions of the external spline of the second spline.

[0016] In a preferred embodiment of the present invention, the first-stage drive assembly includes a star wheel and a planet carrier of the planetary gear assembly, the star wheel is rotatably fixed on the planet carrier, and the second-stage drive assembly includes a gear ring in the planetary gear assembly, and the second spline is arranged on the gear ring and rotates with the gear ring.

[0017] In a preferred embodiment of the present invention, the second pawl ratchet includes a rotating shaft, and a driving arm connected to the rotating shaft and rotating around the rotating shaft, the distal end of the driving arm away from the rotating shaft is used to couple or decouple with the multiple key portions, the distal end is arranged at a position radially close to the multiple key portions, and the rotating shaft is arranged at a position radially away from the multiple key portions.

[0018] In a preferred embodiment of the present invention, the driving arm has a first width at its distal end away from the rotating shaft and a second width at its proximal end close to the rotating shaft; the first width is smaller than the second width, and an arc-shaped transition portion is formed at the transition point between the first width and the second width.

[0019] In a preferred embodiment of the present invention, the multiple key portions include a matching groove for matching with the distal end, and a driving surface and a circumferential outer arc surface for decoupling the second pawl and the second spline; the driving surface is a slope surface that rises obliquely to the circumferential outer arc surface.

[0020] In a preferred embodiment of the present invention, when the second pawl ratchet surpasses the multiple key portions, the second pawl ratchet rises to the circumferential outer arc surface along the driving surface of the key portion located in front of the rotation direction of the shell, and the arc-shaped transition portion close to the side of the rotating shaft is matched with the circumferential outer arc surface so that the distal end of the driving arm is deflected a certain angle away from the circumferential outer arc surface. This angle enables the retaining structure of the second clutch plate in the second clutch to be matched with the distal end of the second pawl ratchet to complete the decoupling of the power transmission relationship between the second pawl ratchet and the second spline external spline.

[0021] In a preferred embodiment of the present invention, the outer spline of the second spline includes at least 12 or 14 key portions.

[0022] In a preferred embodiment of the present invention, the second clutch comprises: a second clutch plate, a second centrifugal block, and a second pawl; the second centrifugal block is fixed to the second end cover of the hub shell via a rotating shaft; the second end cover comprises a groove for accommodating the second pawl, the groove comprising an axis groove, and the rotating shaft of the second pawl can rotate within the axis groove;

[0023] When the rotation speed of the hub shell exceeds the second rotation speed, the second centrifugal block drives the second clutch plate to rotate in a direction opposite to the rotation direction of the hub shell, so that the second clutch plate rotates to a first position. In the first position, the second clutch plate couples the second pawl with the outer spline of the second spline.

[0024] When the hub shell is lower than the second speed, the second centrifugal block drives the second clutch plate to rotate in the same direction as the rotation direction of the hub shell, so that the second clutch plate rotates to the second position. In the second position, the second clutch plate decouples the second pawl from the external spline of the second spline.

[0025] In a preferred embodiment of the present invention, the bearing pressure of the mating surface when the second pawl is coupled to the second spline is F=T / R1, where R1 is the radius of the outer spline of the second spline, and T is the input torque of the planetary gear set.

[0026] In a preferred embodiment of the present invention, it further comprises:

[0027] a third-stage drive assembly connected to the second-stage drive assembly via a planetary gear set;

[0028] The third stage drive assembly includes a third clutch, the third clutch being fixed to the hub shell and rotating with the hub shell; and a third spline for driving the hub shell;

[0029] The third clutch includes a third pawl that couples or decouples the power transmission relationship between the third spline and the hub shell according to the rotational speed of the hub;

[0030] The third pawl ratchet is provided on the outer peripheral side of the third spline.

[0031] The third spline includes an external spline, and the third pawl is coupled to or decoupled from a plurality of key portions of the external spline of the third spline.

[0032] In a preferred embodiment of the present invention, the third clutch of the third-stage drive assembly and the second clutch of the second-stage drive assembly are mirror-image structures.

[0033] In a preferred embodiment of the present invention, the outer spline of the third spline includes at least 14 or 12 key portions;

[0034] In a preferred embodiment of the present application, the gear ring of the planetary gear set includes a fourth spline, and the fourth spline includes an external spline. The fourth spline is matched with the internal spline of the second spline to transmit the power of the gear ring to the second spline.

[0035] In a preferred embodiment of the present invention, the fourth spline includes an internal spline, the third-stage drive assembly includes a planetary carrier assembly, and the planetary carrier assembly includes a fifth spline matched with the internal spline of the fourth spline.

[0036] In a preferred embodiment of the present invention, the third-stage drive assembly includes a gear ring matched with the planetary carrier assembly, the gear ring includes a sixth spline, the sixth spline is an external spline, and the sixth spline is matched with the internal spline of the third spline.

[0037] In a preferred embodiment of the present invention, the third clutch includes: a third clutch plate, a third centrifugal block, and a third pawl ratchet; the third centrifugal block is fixed to the third end cover of the hub shell through a rotating shaft; the third end cover includes a groove for accommodating the third pawl ratchet, and the groove includes an axis groove, and the rotating shaft of the third pawl ratchet can rotate in the axis groove.

[0038] When the rotation speed of the hub shell exceeds the third rotation speed, the third centrifugal block drives the third clutch plate to rotate in a direction opposite to the rotation direction of the hub shell, so that the third clutch plate rotates to the first position. In the first position, the third clutch plate couples the third pawl with the third external spline.

[0039] When the hub shell is lower than the third speed, the third centrifugal block drives the second clutch plate to rotate in the same direction as the rotation direction of the hub shell, so that the third clutch plate rotates to the second position. In the second position, the third clutch plate decouples the third pawl from the third external spline.

[0040] In a preferred embodiment of the present invention, during the acceleration of the hub shell / vehicle: when the hub shell reaches a first speed, the first gripping ratchet directly drives the hub shell, the second pawl ratchet is decoupled from the second spline, and the third pawl ratchet is decoupled from the third spline; when the hub shell reaches a second speed, the first pawl ratchet is in an overtaking state, the second pawl ratchet is coupled to the hub shell, and the third pawl ratchet is decoupled from the third spline; when the hub shell reaches a third speed, the first pawl ratchet and the second pawl ratchet are in an overtaking state, and the third pawl ratchet is coupled to the third spline.

[0041] In a preferred embodiment of the present invention, when the speed of the hub shell is higher than a third speed, the first pawl ratchet, the second pawl ratchet and the third pawl ratchet are all in an overrunning state.

[0042] In a preferred embodiment of the present invention, the third speed>the second speed>the first speed.

[0043] In a preferred embodiment of the present invention, during the deceleration process: when the hub shell is lower than the third speed but higher than the second speed, the third pawl ratchet is in an uncoupled state, the second pawl ratchet is in an overtaking state, and the first pawl ratchet is in an overtaking state; when the hub shell is at the second speed, the third pawl ratchet is in an uncoupled state, the second pawl ratchet is in a coupled state, and the first pawl ratchet is in an overtaking state; when the hub shell is lower than the second speed but higher than the first speed, the third pawl ratchet is in an uncoupled state, the second pawl ratchet is in an uncoupled state, and the first pawl ratchet is in an overtaking state; when the hub shell is at the first speed, the third pawl ratchet is in an uncoupled state, the second pawl ratchet is in an uncoupled state, and the first pawl ratchet is in a coupled state.

[0044] In a preferred embodiment of the present invention, the hub shell is a closed shell, and the second end cover and the third end cover are fixed inside the closed shell.

[0045] In a preferred embodiment of the present invention, the second end cover and the third end cover are detachably fixed to the main body of the shell.

[0046] In a preferred embodiment of the present invention, the second end cover is provided with a through hole for the fourth spline to pass through, and the third end cover is provided with a through hole for the fifth spline to pass through.

[0047] In a preferred embodiment of the present invention, the second spline includes an external spline and an internal spline, the radius of the external spline is R1, the radius of the internal spline is R2, and the radius of R2 is <R1。

[0048] Compared with the prior art, the present application has many improvements: 1. The second and third pawls are arranged on the outer peripheral side of the second spline and the third spline, and are matched with the key portion of the outer periphery of the spline. Since the outer radius of the second spline and the third spline is larger, the torque is increased, so that the end face of the pawl is subjected to less torsional force when matching with the spline, and the stress on the matching end face is smaller, thereby avoiding the problem of the pawl being damaged or stuck and causing the inability to shift gears; 2. Compared with the prior art where the pawl is arranged inside the inner spline and matched with the inner spline, more key portions can be set on the outer spline, so that the same rotation At low speed or riding speed, the engagement time of the pawl and the spline is shorter, which can reduce the sense of frustration when shifting gears; 3. The second and third clutches are fixed to the hub shell through the second end and the third end cover of the hub shell. The centrifugal weight of the clutch works with the rotation speed of the hub shell. The timing of coupling or decoupling of the second and third pawls and the external spline is determined by the hub shell, that is, by the actual driving speed of the bicycle. When the user is gliding, the speed-changing hub will also shift to the appropriate gear according to the gliding speed. There is no need to let the user shift gears by free pedaling first, thereby avoiding the problem of users pedaling in vain and preventing users from losing balance due to free pedaling, thereby improving the riding experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG1 is a schematic diagram of the overall structure of the speed-changing hub of Example 1.

[0050] FIG2 is a schematic diagram of the axial cross-sectional structure of the speed-changing hub of Example 1.

[0051] Figure 3 is a schematic diagram of the axial decomposition structure of the speed hub of Example 1.

[0052] FIG4 is a schematic diagram of the structure of the driving body of the speed-changing hub in Example 1.

[0053] FIG5 is a schematic diagram of the axial decomposition structure of the second clutch of the speed-changing hub in Example 1.

[0054] Figure 6 is a schematic diagram of the second spline structure of the speed hub in Example 1.

[0055] FIG7 is a schematic diagram of the second pawl structure of the speed-changing hub in Example 1. FIG.

[0056] Figure 8 is a schematic diagram of the second end cover of the speed hub in Example 1.

[0057] FIG9 is a schematic diagram of the second clutch plate of the speed-changing hub of Example 1.

[0058] Figure 10 is a schematic diagram of the centrifugal block structure of the speed hub in Example 1.

[0059] FIG11 is a schematic diagram of the second clutch upshift and downshift state of the speed hub of Example 1.

[0060] Figure 12 is a schematic diagram of the axial cross-sectional structure of the speed-changing hub of Example 2.

[0061] Figure 13 is a schematic diagram of the hub shell structure of embodiment 2.

[0062] Figure 14 is a schematic diagram of the third end cover structure of Example 2.

[0063] Figure 15 is a schematic diagram of the axial decomposition structure of the second planetary gear set and the third planetary gear set in Example 2. DETAILED DESCRIPTION

[0064] The following is a further detailed description of the technical solution of the present application in conjunction with the accompanying drawings to help those skilled in the art understand the technical solution of the present application, but it should not be regarded as limiting the scope of protection. The scope of protection of the present application shall be based on the definition of the claims.

[0065] The terms "first" and "second" in this application are intended to distinguish different technical features, rather than to limit the scope of protection. The term "coupling" refers to the mechanical connection between different components through direct or indirect power transmission, and the term "decoupling" refers to the release of the direct or indirect power transmission relationship between different components. The term "axial" refers to the extension direction of the axis of the hub shell, or a direction parallel to the extension direction. The term "radial" refers to the extension direction of the diameter of the rotating surface of the hub component. The term "overtaking state" refers to a state in which the rotation speed of the pawl is less than that of the mating hub shell or spline and other components, and the position of the pawl is overtaken by these components in the rotation direction.

[0066] Example 1

[0067] Overall external structure of the speed hub

[0068] Referring to Figure 1 , the speed-shifting hub comprises a hub housing 104 and a hub axle 100. The hub is supported entirely on the hub axle 100, which can optionally be coaxial with a bicycle, electric vehicle, or motor shaft. Fixing nuts 101 are provided at both ends of the hub axle 100 for securing the hub axle 100 to the vehicle. These fixing nuts 101 can preferably be replaced with quick-release nuts.

[0069] Referring to Figures 1, 2, and 3, a drive flywheel 103 is provided for inputting power to the hub. This drive flywheel 103 is optionally connected to a user's chain, which in turn is optionally connected to a pedal flywheel or motor drive. The drive flywheel 103 is directly connected to the power input device of the first-stage drive assembly L1 of the speed-shifting hub, serving as the overall power input source for the speed-shifting hub. The hub housing 104 is connected to the vehicle's wheel hub, outputting raw or shifted power to the wheel hub to automatically change the vehicle's travel speed.

[0070] The hub housing 104 includes a main body 106 and a second end cap 800. The side of the hub housing 104 near the flywheel forms the main body 106 of the hub housing 104. This main body forms the primary space for accommodating the internal components of the hub housing 104. The second end cap 800 is connected to the main body 106 via screws and other fixing components and is fixed to one side of the main body 106. Furthermore, within the hub housing 104, the second end cap 800 is used to secure the second clutch 1000 (as shown in FIG. 5 ) of the second-stage drive assembly L2. This allows the second clutch 1000 to automatically select upshifts or downshifts based on the hub housing's rotational speed.

[0071] By securing the second clutch 1000 to the second end cap 800 of the hub housing 104, the second clutch 1000 can rotate synchronously with the hub housing 104 and shift gears according to the speed of the hub housing 104. When the user coasts (for example, stopping pedaling and letting the vehicle slide downhill), the gear position of the hub changes with the vehicle speed. In the prior art, however, the clutch typically rotates with the drive assembly. Therefore, before the user pedals again while the vehicle is coasting, the drive assembly speed must first be raised to the clutch's shift threshold. During this process, the user experiences little pedaling resistance. However, after shifting gears, the clutch suddenly engages, increasing pedaling resistance. This results in a brief period of inertia and a poor riding experience. After the second clutch 1000 is fixed to the second end cover 800 of the hub shell 104 in this application, the second clutch 1000 rotates with the hub. Even if the user pedals again after sliding, the power can be output to the hub shell 104 through the second clutch 1000. When shifting gears, the riding experience is no different from that of a bicycle without automatic shifting, and the riding experience eliminates the feeling of stepping on air after sliding or temporarily stopping pedaling.

[0072] Referring to Figures 2, 3, and 4, the first-stage drive assembly L1 includes a drive body 400. The hub housing 104 includes the first-stage drive assembly L1, which is used to directly drive the hub housing 104. The first-stage drive assembly L1 includes the drive body 400 connected to the drive flywheel 103. The drive flywheel 103 is fixed to the drive body 400 via a snap-fit ​​structure. The drive flywheel 103 also transmits rotational power to the drive body 400 via the snap-fit ​​structure. A groove 203 is provided at the connection between the drive body 400 and the drive flywheel 103, allowing the circular opening 107 inscribed in the drive flywheel 103 to enter. A snap ring 204 is provided within the groove 203 to axially secure the position of the drive flywheel 103 and prevent axial movement of the drive flywheel 103.

[0073] The driving body 400 includes a structure for driving the hub shell 104 and a portion of the planetary gear set 205 for connecting to the second-stage drive assembly L2. The driving body 400 is a hollow structure, and its end near the drive flywheel 103 is sealed by a sealing ring 201. A first ball bearing 211 and a second ball bearing 212 are disposed within the hollow cavity 401 of the driving body 400. The first ball bearing 211 and the second ball bearing 212 are restrained within the hollow cavity 401 by a retaining spring 202 within the hollow cavity 401. At the same time, the first ball bearing 211 and the second ball bearing 212 rest on the hub axle 100. A step structure 108 is provided on the surface of the hub axle 100 to limit the axial position of the first ball bearing 211 and the second ball bearing 212. This structure can limit the axial position of the driving body 400.

[0074] Referring to Figure 4, the side of the driving body 400 away from the driving flywheel 103 includes a first pawl ratchet mounting seat 402, the diameter of the first pawl ratchet mounting seat 402 is increased, and the first pawl ratchet mounting seat 402 includes a mounting groove 403 for mounting the first pawl ratchet 420, the first pawl ratchet 420 includes a driving arm 421, and a rotating shaft 422 connected to the driving arm 421; the first pawl ratchet mounting groove 403 includes a driving arm groove 404 and an axis groove 405 corresponding to the driving arm 421 and the rotating shaft 422, and the first pawl ratchet 420 can rotate in the mounting groove 403.

[0075] The mounting seat 402 includes a spring mounting groove 406 arranged around the mounting seat 402, and a hoop spring 425 is installed in the spring mounting groove 406. At the same time, a mounting groove 423 for installing the hoop spring 425 is provided on the first pawl ratchet 420, and the first pawl ratchet 420 sets the hoop spring 425 fulcrum 424 at a position close to the rotating shaft 422, so that the contraction force of the hoop spring 425 acts on the fulcrum 424 behind the rotating shaft 422, further enabling the driving arm 421 of the first pawl ratchet 420 to open a certain angle away from the mounting groove 403, so that at low speed (the speed hub is in first gear), the first pawl ratchet 420 always remains connected with the gear ring 105 of the hub shell 104.

[0076] When the driving body 400 rotates, the first pawl ratchet 420 directly drives the toothed ring 105 of the hub housing 104. The toothed ring 105 of the hub housing 104 is installed inside the hub housing 104 and further transmits power to the hub housing 104. When the rotation speed of the hub housing 104 is higher than the rotation speed of the driving body 400, the first pawl ratchet 420 is overtaken by the toothed ring 105 of the hub housing 104. When the first pawl ratchet 420 is overtaken by the teeth on the toothed ring 105 of the hub housing 104, the driving arm 421 of the first pawl ratchet 420 elastically retracts around the rotating shaft 422. When the driving arm 421 of the first pawl ratchet 420 is between two consecutive teeth of the toothed ring 105, it is reset by the hoop spring 425. At this time, the first pawl ratchet 420 is in the overtaking state, and the power of the driving body 400 is not directly transmitted to the hub housing 104.

[0077] The outside of the driving body 400 includes a third ball bearing 213, and a stop ring 407 is provided on the side of the third ball bearing 213 axially close to the driving flywheel 103. The stop ring 407 is used to limit the axial position of the third ball bearing 213. The third ball bearing 213 is used to support the hub shell 104, so that the hub shell 104 can rotate freely relative to the driving body 400, and at the same time, the hub shell 104 can rotate at different relative speeds under different gears.

[0078] A planetary gear carrier 408 is disposed on one side of the mounting base 402 of the driver 400. The planetary gear carrier 408 includes three planetary gears 409 and a planetary gear shaft 411 for mounting the planetary gears. The three planetary gears 409 mesh with the sun gear 102 (see FIG. 3 ) disposed at the center of the hub axle 100. When the driver 400 rotates, the planetary gear carrier 408 and the planetary gears 409 rotate. The rotation of the planetary gears 409 simultaneously drives the ring gear 410 of the planetary gear set 205. Because the sun gear 102 is fixed and the planetary gear carrier 408 rotates, the rotational speed of the ring gear 410 of the planetary gear set 205 is higher than that of the driver 400.

[0079] Second stage drive components

[0080] Referring to Figures 2, 3, and 5, the second-stage drive assembly L2 is connected to the first-stage drive assembly L1 via the planetary gear set 205. The second-stage drive assembly L2 includes a second clutch 1000 and a second spline 600 for driving the hub housing 104. The ring gear 410 of the planetary gear set 205 includes a fourth spline 413. This fourth spline 413 is an external spline that meshes with the second spline 600 to transmit power to the second clutch 1000.

[0081] Second clutch

[0082] The second clutch 1000 includes: a second clutch plate 900, a second centrifugal block 1100, and a second pawl ratchet 700; the second centrifugal block 1100 is fixed to the second end cover 800 through a rotating shaft 1101; the second end cover 800 includes a groove 804 for accommodating the second pawl ratchet 700, and the groove 804 includes an axis groove 805, and the rotating shaft 701 of the second pawl ratchet 700 can rotate in the axis groove 805.

[0083] 5 , the second clutch 1000 is secured to the hub housing 104 via a second end cap 800 and rotates with the hub housing 104. The second clutch 1000 couples or decouples the power transmission relationship between the second spline 600 and the hub housing 104 according to the rotational speed of the hub housing 104. The second pawl 700 is disposed on the outer periphery of the second spline 600.

[0084] Referring to Figures 5 and 7 , in the prior art, the clutch and its pawl typically rotate with the hub, and the pawl is disposed within the inner spline of the spline (equivalent to the second spline 600 of the present application). However, the second pawl 700 of the present application is disposed on the outer periphery of the second spline 600, which simplifies the assembly structure compared to the solution in which the pawl is disposed on the inner spline. Furthermore, when the second pawl 700 mates with the outer spline, the outer spline has a larger radius. Under the same torque, the second pawl 700 and the outer spline of the second spline 600 are subjected to less torque, and the stress on the mating end face 703 is reduced, thereby preventing damage or jamming of the second pawl 700, which could cause an inability to shift gears.

[0085] Second spline

[0086] Referring to Figures 5, 6, and 11, the second spline 600 includes an external spline 601 and an internal spline 608. The second pawl 700 couples or decouples with the multiple key portions 602 of the external spline 601 of the second spline 600. The external spline 608 includes multiple key portions 602, and the internal spline 608 includes multiple key portions 612. Each key portion 602 of the external spline has the same structure, and each key portion 612 of the internal spline 608 has the same structure. The key portion 612 of the internal spline 608 includes a first inclined surface 609, a second inclined surface 610, and a top surface 603 connected to the first inclined surface 609 and the second inclined surface 610. The inclination angle of the first inclined surface 609 is greater than the inclination angle of the second inclined surface 610. The key portion 612 of the internal spline 608 is used to mate with the fourth spline 413 of the gear ring to receive the power of the gear ring 410 , that is, the second spline 600 is provided on the gear ring 410 and rotates with the gear ring 410 .

[0087] Between multiple key portions 612 of the internal spline 608, a circumferential spacing space 611 is formed. This circumferential spacing space 611 is used to circumferentially accommodate the key portions of the fourth spline 413 of the toothed ring 410, and the circumferential spacing of the fourth spline 413 is smaller than the circumferential spacing space 611 between the key portions of the internal spline, such that a circumferential buffer space is formed between the fourth spline 413 of the toothed ring and the key portions 612 of the internal spline 608 of the second spline 600. This buffer space can reduce the spline impact during gear shifting.

[0088] The multiple key portions 602 of the external spline include a mating groove 604 for mating with the second pawl 700, a circumferential outer arc surface 605, and a driving surface 606. The driving surface 606 is a ramp surface that slopes upward to the circumferential outer arc surface 605. The mating groove 604 is generally of a "J" - shaped cross - section structure, with its bottom being semi - circular. The radial height of the mating groove 604 is smaller than the circumferential outer arc surface 605 and the driving surface 606, and a buffer surface 607 is provided between the mating groove 604 and the driving surface 606.

[0089] Referring to FIG. 11, the radius of the external spline 601 of the second spline 600 is R1, and the radius of the internal spline 608 is R2, where R2 < R1. Assuming the torque is T, the torque of the internal spline is F1, and the torque of the external spline is F2, then T = F1 * R1 = F2 * R2, and F2 = F1 * (R1 / R2). Since R2 < R1, F2 < F1. This smaller F2 reduces the stress impact on the mating surface 703 of the second pawl 700 and can prevent the second pawl 700 from being damaged or stuck.

[0090] When the second pawl 700 mates with the external spline 601 of the second spline 600, it can reduce the gear - shifting response time. Since the diameter of the external spline 601 of the second spline 600 is larger, the number of key portions 602 of the external spline 601 of the second spline 600 is relatively more than that of the key portions 612 of the internal spline 608. Correspondingly, the engagement time between the second pawl 700 and the key portions 602 after gear shifting is shorter. In a preferred scheme, the number of key portions 602 of the external spline 601 of the second spline 600 is set to at least 10. In a preferred scheme, the number of key portions 602 of the external spline 601 of the second spline is set to at least 14 or 12. Its response time after gear shifting is approximately t1=(2π / 14) / w or (2π / 12) / w, where w is the angular velocity of rotation. It can be seen that the response time is inversely proportional to the number of key portions 602. Relatively speaking, the larger circumferential size of the external spline 601 allows it to have more key portions 602 than the internal spline, and the corresponding gear - shifting response time is shorter, and there will be no impact force and impact sound on the meshing surface between the pawl and the key portions 602 during gear engagement.

[0091] Second pawl

[0092] 7 and 11 , a second pawl 700 is disposed on the outer periphery of the second spline 600 and is mounted in a recess 804 of an end cap 800 of the hub shell 104 on the second clutch 1000. The second pawl 700 includes a rotating shaft 701 and a driving arm 702 connected to and rotating about the rotating shaft 701. The driving arm 702 has a distal end (at an end surface 703 and a portion near the end surface) distal from the rotating shaft 701 for coupling with or decoupling from the plurality of key portions. The distal end is located near the plurality of key portions 602, and the rotating shaft 701 is located distal from the plurality of key portions 602. During coupling, the end surface 703 of the driving arm 702 contacts the surface of the mating groove 604, transmitting power to the hub shell 104 through the end surface 703.

[0093] The center of the second pawl 700 includes a spring slot 704. The spring slot 704 extends through the thickness of the second pawl 700 and forms an inclined surface 705 near the rotating shaft 701 for the spring to rest on. A spring 706 is disposed within the second pawl 700 to deflect the driving arm 702 of the second pawl 700 to a position close to the second spline key portion 602 when the second pawl 700 is not constrained by the second clutch plate 900.

[0094] The driving arm 702 has a first width W1 at its distal end away from the rotating shaft 701 and a second width W2 at its proximal end near the rotating shaft 701. The first width W1 is smaller than the second width W2, and the transition between the first width W1 and the second width W2 forms an arcuate transition portion 708. The first width W1, the second width W2, and the arcuate transition portion 708 function to allow the distal end of the driving arm 702 of the second pawl 700 to tilt up to a certain angle when the second pawl 700 passes over the key portion 602. The angle is approximately the angle b shown in FIG11 . With the smaller first width W1 and the angle b, a gap C is formed between the outer circumferential surface 605 and the driving arm 702 of the second pawl 700. This gap C allows the retaining structure 904 of the second clutch plate 900 to enter, thereby decoupling the second pawl 700 from the second spline 600.

[0095] 9 and 11 , in a preferred embodiment of the present invention, when the second pawl ratchet 700 surpasses the multiple key portions 602, the second pawl ratchet 700 rises along the driving surface 606 of the key portion located in front of the rotation direction A of the hub shell 104 to the circumferential outer arc surface 605, and the arc-shaped transition portion 708 close to the side of the rotating shaft 701 is matched with the circumferential outer arc surface 605 so that the distal end of the driving arm 702 is deflected a certain angle away from the circumferential outer arc surface to form a gap C. The gap C enables the retaining structure 904 of the clutch plate 900 in the second clutch 1000 to be matched with the distal first width W1 of the second pawl ratchet 700 to complete the decoupling of the second pawl ratchet 700 from the external spline 601 of the second spline 600.

[0096] Second end cap

[0097] 5 and 8 , the second end cap 800 is divided into an inner surface 801 and an outer surface 802. The outer surface 802 of the second end cap 800 is penetrated by a plurality of screws (not shown) for securing the second end cap 800 to the main portion 106 of the housing. The second end cap 800 is provided with a plurality of fixing holes 803 for the screws to pass through. These screws pass through the fixing holes 803 to secure the second end cap 800 to the main portion 106 of the hub housing 104. The end cap 800 and the main portion 106 of the hub housing 104 are sealed together, and a sealing gasket may be optionally provided on the connecting surface between the two. The second end cap 800 includes a plurality of thickened steps 806, each of which is provided with a plurality of fixing holes 807. These fixing holes 807 are used to secure the shaft 1101 of the second centrifugal weight 1100. The second centrifugal weight 1100 is fixed to the fixing holes 807 of the second end cap 800 of the hub housing 104 via the rotating shaft 1101.

[0098] The inner surface 801 of the second end cap 800 is used to secure the second clutch 1000. The second end cap 800 has a certain axial thickness, which ensures that a circular cavity 808 is formed within the second end cap 800. The circumferential wall of the circular cavity 808 includes an annular groove 809 for accommodating a spring. The annular groove 809 is used to secure the return spring 706 of the second pawl 700. The circumferential wall of the circular cavity 808 includes a groove 804 for accommodating the second pawl. The groove 804 includes an axial groove 805 and a groove 812 for accommodating the second pawl drive arm 702. When the second pawl 700 is in the released state, the drive arm 702 deviates from the groove 812, and the second pawl 700 can engage / match with the key portion 602 of the second spline 600, or the second pawl 700 can be in the overrunning state.

[0099] The outer periphery of the circular cavity 808 includes a plurality of arc-shaped baffles 813. The function of the arc-shaped baffles 813 is to fix the radial position of the clutch plate 900 and allow the clutch plate 900 to rotate at a certain angle so that the clutch plate 900 can switch between the first position P1 and the second position P2, thereby controlling the coupling or decoupling of the second pawl 700 and the second spline 600 through the clutch plate 900.

[0100] The outer periphery of the circular cavity 808 includes a plurality of limiting members 814 , the structures of which are similar to the arc-shaped retaining strips 813 . The limiting members 814 contact the outer periphery of the clutch plate 900 to limit the radial position of the clutch plate 900 .

[0101] clutch plate

[0102] 9 , the clutch plate 900 includes a mounting hole 901 at its center. When installed, the clutch plate 900 is mounted on the fourth spline 413 of the gear ring 410. The diameter of the mounting hole 901 is equal to the diameter of the fourth spline 413. Four independent positioning holes 902 are included on the periphery of the mounting hole 901. The positioning holes 902 are mounted on the plurality of limiting members 814. The arc length of the positioning holes 902 is greater than that of the plurality of limiting members 814, so that the clutch plate 900 has axial rotation space.

[0103] Pawl-ratchet clutch holes 903 are arranged at intervals between the mounting holes 901 in the circumferential direction. The pawl-ratchet clutch holes 903 are symmetrically arranged about the center of the clutch plate mounting hole 901. A retaining structure 904 is arranged in the pawl-ratchet clutch hole 903. The retaining structure 904 is used to maintain the decoupling state of the second pawl-ratchet 700 and the second spline 600 when the second pawl-ratchet 700 is decoupled from the second spline 600. The second pawl-ratchet 700 has a first axial length W3 so as to be matched with the second spline 600 or the clutch plate 900 at different axial positions in the coupled or decoupled state.

[0104] When the retaining structure 904 is mated with the second pawl ratchet 700, the retaining structure 904 extends into the radial interior of the distal end of the driving arm 702 of the second pawl ratchet 700, and the radial height of the upper edge of the retaining structure 904 is higher than the radial height of the key portion 602 of the second spline 600, so that when the retaining structure 904 is mated with the second pawl ratchet 700, the second pawl ratchet 700 is separated from the key portion 602 of the second spline 600.

[0105] The clutch plate 900 also includes a centrifugal block 1100 adapter hole 905, which is roughly a "T"-shaped hole, consisting of a first capsule hole 911 and a second capsule hole 912. The first capsule hole 911 has a larger radial size and length, and the first capsule hole 911 and the second capsule hole 912 are interconnected. The centrifugal block 1100 is arranged above the first capsule hole 911 but does not interfere with the capsule hole.

[0106] Clutch plate 900' shown in Figure 11 is another embodiment of clutch plate 900'. Its structural differences from clutch plate 900 shown in Figure 9 primarily lie in: it lacks a hole equivalent to adapter hole 905; the centrifugal mass shaft 1101 is directly fixed to end cap 800; clutch plate 900' has a circular outer contour, and its diameter is smaller than the maximum diameter of clutch plate 900 shown in Figure 9. The operating principle of clutch plate 900' is identical to that of clutch plate 900, and no distinction is made in the description of the operating principle in this application.

[0107] centrifugal block

[0108] Referring to Figure 10 , the mounting shaft 1101 of the centrifugal weight 1100 is secured to the second end cap 800 via the capsule hole 905 in the clutch plate 900. The first capsule hole 911 is larger than the diameter of the mounting shaft 1101, allowing room for the clutch plate 900 to rotate. A return spring 1102 is provided on the mounting shaft 1101 of the centrifugal weight 1100. Adjusting the torque of this return spring 1102 can adjust the critical shift speed of the clutch 1000 accordingly. The centrifugal block 1100 also includes a drive rod 1103. The drive rod 1103 drives the clutch plate 900 to rotate. When the drive rod 1103 rotates with the clutch plate 900, the drive rod 1103 rotates around the centrifugal block 1100 mounting shaft 1101 and converts the rotation around the axis into rotation of the clutch plate 900 through the second capsule hole 912. Obviously, during the rotation of the clutch plate 900, the drive rod 1103 will move radially outward or radially inward relative to the second capsule hole 912.

[0109] Gear shifting process of the speed hub

[0110] 5 and 11 , when the user is riding in first gear or a drive device (e.g., a motor) drives the driver 400 to rotate, the driver 400 rotates along with the drive flywheel 103, and the speed of the driver 400 always remains the same as the input speed. The first pawl 420 on the driver 400 engages with the toothed ring 105 of the hub shell 104 and directly drives the hub shell 104 via the toothed ring 105. At this time, the rotation speed of the hub shell 104 is the same as the rotation speed of the driver 400. Simultaneously, the rotation speed of the hub shell 104 has not reached the critical speed for shifting the second clutch 1000, and the second clutch 1000 rotates along with the hub shell 104. The toothed ring 410 of the planetary gear set 205 rotates at a higher speed than the driver 400, and the second spline 600 rotates along with the toothed ring 410 of the planetary gear set 205. At this time, the second spline 600 is in an idling state and does not output power to the hub shell 104. At this time, the driving arm 702 of the second pawl 700 is held by the retaining structure 904 of the clutch plate 900 , so that the driving arm 702 is not engaged with the key portion 602 of the second spline 600 .

[0111] When shifting from first gear to second gear, the user accelerates until the rotation speed of the hub shell 104 reaches the critical speed (the second speed) of the second clutch 1000. The centrifugal force (defined in a non-inertial reference frame) of the centrifugal weight 1100 overcomes the return force of the return spring 1102, driving the second clutch plate 900 to rotate in the opposite direction (opposite to the rotation direction of the hub shell 104) to rotate the second clutch plate 900 to the first position p1. In the first position p1, the retaining structure 905 of the clutch plate 900 releases the second pawl 700. After being released, the second pawl 700 rotates about the axis 701 under the action of the spring 706, and the driving arm 702 engages with the key portion 602 of the external spline of the second spline 600, so that the hub shell 104 is directly driven by the second spline 600. The driving force of the second spline 600 is transmitted to the second end cover 800 through the second pawl 700, and then transmitted to the hub shell 104 through the second end cover 800. At this point, the hub housing 104 rotates at the same speed as the ring gear 410 of the planetary gear set 205 and the second spline 600. Due to the acceleration of the planetary gear set 205, the hub housing 104 and the ring gear 105 of the hub housing 105 rotate at speeds greater than the first pawl 420, causing the first pawl 420 to be in an overrunning state. After reaching the critical speed, the centrifugal weight 1100 maintains the position of the centrifugal disc 900 without resetting.

[0112] When downshifting from the second gear to the first gear, when the user stops pedaling or the pedaling speed slows down (below the second speed), the speed of the hub shell 104 gradually decreases to below the critical speed. At this time, the centrifugal block 1100 is reset under the action of the reset spring 1102. During the reset process of the centrifugal block 1100, the clutch plate 900 is reset and rotated (the rotation direction is the same as the rotation direction of the hub shell) to the second position P2. At this time, the speed of the hub shell 104 is greater than the speed of the second spline 600, and the front end of the second pawl 700 exceeds the speed of the second spline 600. The driving surface 606 of the key portion in the front of the hub shell 104 in the rotation direction A rises to the circumferential outer arc surface 605. The arc-shaped transition portion 708 near the side of the second pawl ratchet shaft 701 engages with the circumferential outer arc surface 605, causing the distal end of the driving arm 702 to deflect a certain angle away from the circumferential outer arc surface 605 to form a gap C. This gap C allows the retaining structure 904 of the clutch plate to engage with the distal end of the second pawl ratchet 700 during the reset process, thereby completing the decoupling of the second pawl ratchet 700 from the outer spline 601 of the second spline 600. At this time, if the user stops pedaling, the first pawl ratchet 420 remains in the overrunning state. If the user pedals again and the rotation speed of the driving body 400 is the same as or greater than the rotation speed of the hub shell 104, the first pawl ratchet 420 re-engages with the gear ring 105 of the hub shell 104, and drives the hub shell 104 to continue rotating in the first gear.

[0113] It should be noted that the power transmission paths are different in first gear and second gear. In first gear, power is transmitted to the driving body 400 through the driving flywheel 103 (or motor shaft), then transmitted to the first pawl ratchet 420 through the driving body 400, and then transmitted to the ring gear 105 of the hub shell through the first pawl ratchet 420, and then transmitted to the hub shell 104 through the ring gear 105. In second gear, power is transmitted to the driving body 400 through the driving flywheel 103 (or motor shaft), and then transmitted to the star wheel 409, and then transmitted to the ring gear 410 of the planetary gear set 205 through the star wheel 409, and then transmitted to the second spline 600 through the second spline 600. The second pawl ratchet 700 is then transmitted to the second end cover 800 through the second end cover 800, and then to the hub shell 104 through the second end cover 800.

[0114] Example 2

[0115] This embodiment is an improvement proposed on the basis of embodiment 1. Here, the same structure as embodiment 1 is briefly described, and the different structure from embodiment 1 is described in detail. In order to distinguish this embodiment 2 from embodiment 1, new figure marks are used.

[0116] Referring to the three-speed hub structure shown in FIG12 , this differs from Example 1 in that the hub housing 1210 includes a second-stage drive assembly L2 and a third-stage drive assembly L3, both of which are disposed within the hub housing 1210. The second end cap 1202 is connected to the interior of the hub housing 1210, while the third end cap 1400 of the third-stage drive assembly L3 is also connected to the interior of the hub housing 1210. The second-stage drive assembly L2 and the third-stage drive assembly L3 are arranged in a mirror-symmetrical structure, which can reduce the overall axial length of the hub, thereby reducing the overall volume of the hub.

[0117] Hub shell

[0118] 12 and 13 , the hub shell 1210 is divided into a first portion 1211 and a second portion 1212. The first portion 1211 of the hub shell 1210 is used to connect to the second end cover 1202, and the first portion 1211 of the hub shell 1210 also accommodates the first-stage transmission assembly L1. The difference from Embodiment 1 is that the first portion 1211 of the hub includes an axially extended connecting structure 1215, which is embedded in the second portion 1212 of the hub shell 1210 and mates with the inner wall of the second portion 1212 of the hub shell 1210. The first portion 1211 of the hub shell 1210 also includes a connecting end face 1213, and the connecting end face 1213 of the first portion 1211 is connected to the connecting end face 1218 of the second portion 1212 of the hub by screws. The second portion 1212 of the hub housing 1210 includes a plurality of protrusions 1214 arranged along the wall of the hub housing 1210. Each of these protrusions 1214 is provided with screw mounting holes 1216. These protrusions 1214 are used to secure the third end cap 1400 of the third-stage drive assembly L3 to the hub housing 1210. An annular step 1217 is also provided on the outer periphery of each protrusion 1214. This annular step 1217 is axially longer than the protrusion 1214, creating a height difference with the surface of the protrusion 1214. This height difference facilitates the securing of the third end cap 1400. Similarly, the first portion 1211 of the hub housing 1210 is also provided with protrusions 1214 to facilitate the mounting of the second end cap 1202 thereon.

[0119] The hub housing 1210 includes a rotation speed sensor mounting slot 1219 , in which a Hall rotation speed sensor is mounted to determine the hub rotation speed and gear position.

[0120] The third end cover

[0121] Referring to Figures 12, 14 and 15, the main difference between the third end cover 1400 and Example 1 is that a larger opening 1401 is set in the middle of the third end cover 1400 so that the third pawl 1501 and the third spline 1503 can be accommodated inside it, and the position where the sixth spline 1510 on the ring gear 1502 of the third planetary gear set 1500 is matched with the third spline 1503 also passes through this opening 1401.

[0122] In this embodiment, the second end cap 1202 and the third end cap 1400 have the same structure, and a partition 1201 is disposed between the third end cap 1400 and the second end cap 1202. The partition 1201 is used to separate the second pawl 1513, the third pawl 1501, the second centrifugal block 1515, and the third centrifugal block 1516, the ring gear 1504 of the second planetary gear set 1512, and the ring gear 1502 of the third planetary gear set 1500, located within the opening of the second end cap 1202 and the opening 1401 of the third end cap 1400. The partition 1201 prevents axial movement of these components during rotation and prevents interference between these components during rotation. Optionally, the partition 1201 can be fixed to the second end cap 1202 or the third end cap 1400, or it can be freely mounted on the side of the ring gear 1502 of the third planetary gear set 1500.

[0123] The third planetary gear set

[0124] 12 and 15 , which illustrate a second planetary gear set 1512 and a third planetary gear set 1500. The third planetary gear set 1500 includes a third planet carrier 1505 coupled to the second planetary gear set 1512. The third planet carrier 1505 includes a fifth spline 1506 protruding from an end of the third planet carrier 1505. The interior of the fourth spline 1519 includes three internal splines 1509 coupled to the fifth spline 1506. Each internal spline 1509 is an arcuate structure, with arcuate surfaces 1507 at both ends transitioning to the inner surfaces of the fourth splines 1519. The inner surface is provided with three splines 1509, with a space 1520 reserved between each spline. This space allows the fifth spline 1506 to enter and mate with it. Through the engagement of the fifth spline 1506 with the internal spline 1509 of the fourth spline 1519, the power of the ring gear 1504 of the second planetary gear set 1512 can be transmitted to the planet carrier 1505 of the third planetary gear set 1500. To maintain stability, a ball bearing 1508 is included within the fourth spline 1519, on one side of the fifth spline 1506. This ball bearing 1508 is used to support the ring gear 1504 of the second planetary gear set 1512, ensuring smooth and stable rotation with support bearings at both ends of the axial direction.

[0125] The ring gear 1502 of the third planetary gear set 1500 is mounted on the third planetary carrier 1505. The third planetary carrier 1505 is driven by the internal splines 1509 of the second ring gear 1504, which has a second gear speed. Driven by the third planetary carrier 1505, the ring gear 1502 has a third speed. The third spline 1503 is mounted on the sixth spline 1510 of the ring gear 1502. In third gear, the ring gear 1502 mates with the third pawl 1501 to enable the hub housing 1210 to have a third speed. The sixth spline 1510 is an external spline that mates with the internal spline of the third spline 1503. The third clutch has the same structure as the second clutch, and its structure is not further described here.

[0126] Gear shifting process of the speed hub

[0127] The operation of the third centrifugal weight 1516, third clutch plate 1517, and third pawl 1501 during the shifting process in this embodiment is identical to that of the first embodiment, and will not be further described here. The difference is that this embodiment includes three gears, corresponding to the three speeds of the hub housing 1210, with the third speed > the second speed > the first speed.

[0128] In a preferred embodiment of the present invention, during the acceleration of the hub / vehicle: when the hub shell 1210 reaches a first speed, the second pawl ratchet 1513 is decoupled from the second spline 1514, and the third pawl ratchet 1501 is decoupled from the third spline 1503; when the hub shell 1210 reaches a second speed, the first pawl ratchet 1518 is in an overrunning state, the second pawl ratchet 1513 is coupled to the second spline 1514, and the third pawl ratchet 1501 is decoupled from the third spline 1503; when the hub shell 1210 reaches a third speed, the first pawl ratchet 1518 and the second pawl ratchet 1513 are in an overrunning state, and the third pawl ratchet 1501 is coupled to the third spline 1503. When the hub shell 1210 is higher than the third speed, the first pawl ratchet 1518, the second pawl ratchet 1513, and the third pawl ratchet 1501 are all in an overrunning state.

[0129] When the hub shell 1210 is lower than the third speed but higher than the second speed, the third pawl ratchet 1501 is in an uncoupled state, the second pawl ratchet 1513 is in an overtaking state, and the first pawl ratchet 1518 is in an overtaking state; when the hub shell 1210 is at the second speed, the third pawl ratchet 1501 is in an uncoupled state, the second pawl ratchet 1513 is in a coupled state, and the first pawl ratchet 1518 is in an overtaking state; when the hub shell 1210 is lower than the second speed but higher than the first speed, the third pawl ratchet 1501 is in an uncoupled state, the second pawl ratchet 1513 is in an uncoupled state, and the first pawl ratchet 1518 is in an overtaking state; when the hub shell 1210 is at the first speed, the third pawl ratchet 1501 is in an uncoupled state, the second pawl ratchet 1513 is in an uncoupled state, and the first pawl ratchet 1518 is in a coupled state.

Claims

1. A speed-changing hub, comprising: Hub shell; The first-stage driving assembly directly drives the hub shell through the first claw; A second-stage drive assembly is connected to the first-stage drive assembly via a planetary gear set; It is characterized in that The second stage drive assembly includes a second clutch, the second clutch is fixed to the hub shell and rotates with the hub shell, and a second spline for driving the hub shell; The second clutch includes a second pawl ratchet that couples or decouples the power transmission relationship between the second spline and the hub shell according to the rotation speed of the hub shell; The second pawl is disposed on the outer peripheral side of the second spline.

2. The speed-changing hub according to claim 1, characterized in that: The second spline includes an external spline, and the second pawl is coupled to or decoupled from a plurality of key portions of the external spline of the second spline.

3. The speed-changing hub according to claim 2, characterized in that: The second pawl ratchet includes a rotating shaft and a driving arm connected to the rotating shaft and rotating around the rotating shaft. The distal end of the driving arm away from the rotating shaft is used to couple or decouple with the multiple key parts. The distal end is arranged at a position radially close to the multiple key parts, and the rotating shaft is arranged at a position radially away from the multiple key parts.

4. The speed-changing hub according to claim 3, characterized in that: The driving arm has a first width at a distal end away from the rotating shaft, and has a second width at a proximal end close to the rotating shaft; the first width is smaller than the second width, and an arc-shaped transition portion is formed at a transition point between the first width and the second width.

5. The speed-changing hub according to claim 4, characterized in that: The multiple key parts include a matching groove for matching with the distal end, and a driving surface and a circumferential outer arc surface for decoupling the power transmission relationship between the second pawl and the second spline; the driving surface is a slope surface that rises obliquely to the circumferential outer arc surface.

6. The speed-changing hub according to claim 5, characterized in that: When the second pawl ratchet surpasses the multiple key portions, the second pawl ratchet rises to the circumferential outer arc surface along the driving surface of the key portion located in front of the rotation direction of the shell, and the arc-shaped transition portion is matched with the circumferential outer arc surface so that the distal end of the driving arm is deflected a certain angle away from the circumferential outer arc surface. This angle enables the retaining structure of the second clutch plate in the second clutch to be matched with the distal end of the second pawl ratchet to complete the decoupling of the power transmission relationship between the second pawl ratchet and the external spline of the second spline.

7. The speed-changing hub according to claim 2, characterized in that: The external spline of the second spline includes at least 12 or 14 key portions.

8. The speed-changing hub according to claim 1, characterized in that: The second clutch comprises: a second clutch plate, a second centrifugal block, and a second claw ratchet; the second centrifugal block is fixed to the second end cover of the hub shell through a rotating shaft; the second end cover comprises a groove for accommodating the second claw ratchet, the groove comprises an axis groove, and the rotating shaft of the second claw ratchet can rotate in the axis groove; When the hub shell rotates at a speed higher than a second speed, the second centrifugal block drives the second clutch plate to rotate in a direction opposite to the rotation direction of the hub shell, so that the second clutch plate rotates to a first position. In the first position, the second clutch plate couples the power transmission relationship between the second pawl and the outer spline of the second spline. When the hub shell is lower than the second rotation speed, the second centrifugal block drives the second clutch plate to rotate in the same direction as the rotation direction of the hub shell, so that the second clutch plate rotates to a second position. In the second position, the second clutch plate decouples the power transmission relationship between the second pawl and the external spline of the second spline.

9. The speed-changing hub according to claim 1, characterized in that: The bearing pressure of the mating surface when the second pawl is coupled with the second spline is F=T / R1, wherein R1 is the radius of the outer spline of the second spline, and T is the input torque of the planetary gear set.

10. The speed-changing hub according to claim 1, characterized in that: Further including: A third-stage drive assembly connected to the second-stage drive assembly via a planetary gear set; The third stage drive assembly includes a third clutch, the third clutch is fixed to the hub shell and rotates with the hub shell, and a third spline for driving the hub shell; The third clutch comprises a third pawl ratchet for coupling or decoupling the power transmission relationship between the third spline and the hub shell according to the rotation speed of the hub; The third pawl ratchet is disposed on the outer peripheral side of the third spline.

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