A lightweight and efficient through-shaft type wheel hub motor

Abstract

The application discloses a light and efficient through-shaft type wheel hub motor, which comprises a through-shaft, a wheel hub shell mounted on the through-shaft, a machine core, a planetary reduction mechanism and a clutch which are sequentially assembled along the through-shaft, the clutch comprises an outer ring and an inner ring, the inner ring is fixed on the through-shaft, the planetary reduction mechanism comprises a sun gear arranged on an output end of the machine core and a plurality of planetary gears, the planetary gears are arranged on planetary shafts, the planetary shafts are fixed to the outer ring of the clutch, the sun gear is in transmission connection with a ring gear fixed to the inner side of the wheel hub shell through the planetary gears, and the planetary gears are double planetary gears, the double planetary gears comprise coaxially arranged large and small gears, the large gear is a plastic gear and is in mesh with the sun gear, the small gear is a metal gear and is in mesh with the ring gear, and an extension shaft sleeve is integrally arranged at the center of the small gear to fix the large gear. The through-shaft type wheel hub motor can ensure high output power and good internal structural strength under the premise of reducing weight, and the volume is further reduced.

Description

Technical Field

[0001] This invention relates to a lightweight and efficient through-shaft hub motor. Background Technology

[0002] In known technologies, a type of hub motor is manufactured and used in road electric-assist bicycles. The industry often has higher production requirements for the overall weight, volume, structural strength and output power of this type of hub motor.

[0003] As is well known, compared to hub motors with segmented shaft architecture, through-shaft hub motors offer greater structural strength in supporting the motor mechanism, do not limit output torque, do not require concentricity correction between the two shaft segments, have fewer parts, a relatively simpler structure, and are easier to manufacture and assemble. Therefore, through-shaft hub motors are currently the most widely used type in the industry.

[0004] The structural feature of a through-shaft hub motor is that it uses a single through shaft, along which the motor core (including the stator and rotor), planetary reduction mechanism, and clutch are assembled sequentially. Currently, in conventional designs, to achieve a compact structure, the planetary gears in the planetary reduction mechanism are often integrated with the clutch. This involves fixing the clutch to the through shaft as a planetary support, and directly fixing the planetary shaft at the center of the planetary gears to the outer ring of the clutch. A sun gear, fixed to the through shaft at the output end of the motor core, is connected to a gear ring fixed inside the hub housing via several planetary gears in the planetary reduction mechanism. The planetary gears are typically made as a single, double-gear assembly, with the larger gear meshing with the sun gear and the smaller gear meshing with the gear ring. However, this type of through-shaft hub motor still suffers from the following problems in practical use:

[0005] 1) To further reduce weight, known technologies typically employ integrally molded plastic double gears for planetary gears, such as POM (polyoxymethylene), PEEK (polyetheretherketone), and nylon plastics like PA66 and PA46. However, this inevitably leads to a decrease in structural strength. To compensate for this deficiency, current practices often involve making these plastic double gears thicker and larger to enhance structural strength. However, when the diameter of the larger gear in the double gear increases, it causes a decrease in the speed ratio between the larger gear and the sun gear at the rotor output end, ultimately resulting in a reduction in the overall output power of the motor.

[0006] 2) Similarly, when the outer diameter of the large gear in the planetary gear increases, the outer diameter of the entire hub housing will increase, which will ultimately lead to an increase in the overall volume of the hub motor, the amount of material used, the weight, and the cost.

[0007] 3) Existing through-shaft hub motors do not reduce the axial dimension of the entire motor after integrating the planetary gears and clutches, and the internal structure is still not compact or optimized enough. There is still considerable room for improvement to meet the requirements of hub motors used in road electric-assist bicycles. Summary of the Invention

[0008] The purpose of this invention is to provide a lightweight and efficient through-shaft hub motor that, while being lighter in weight, still ensures high output power and good internal structural strength, and is smaller in size and more compact in internal structure, making it more suitable for use in road electric-assist bicycles.

[0009] The technical solution of this invention is: a lightweight and efficient through-shaft hub motor, comprising a through shaft, a hub housing mounted on the through shaft at both ends via housing bearings, and a core mechanism, a planetary reduction mechanism, and a clutch arranged sequentially along the through shaft within the hub housing. The clutch includes an outer ring and an inner ring, with the inner ring fixed on the through shaft. The planetary reduction mechanism includes a sun gear and several planetary gears located on the output end of the core mechanism. The planetary gears are located on a planetary shaft, which is fixed to the outer ring of the clutch. The sun gear is connected to a gear ring fixed inside the hub housing via the planetary gears. The invention is characterized in that the planetary gears are double gears, including a large gear and a small gear arranged coaxially but separately. The large gear is a plastic gear that meshes with the sun gear, while the small gear is a metal gear that meshes with the gear ring. An extension sleeve is integrally provided at the center of the small gear to fix the large gear.

[0010] Furthermore, the outer ring end face of the clutch in this invention is provided with a relief cavity for each planetary gear to be inserted into, and the outer circumference of the outer ring is provided with an opening for each relief cavity to allow the outer peripheral teeth of the pinion to protrude and mesh with the gear ring.

[0011] Furthermore, in this invention, the large gear is injection molded and pressed onto the periphery of the extended bushing of the small gear, or the large gear is fitted into the periphery of the extended bushing of the small gear through a keyway structure.

[0012] Furthermore, the hub housing of the present invention is provided with a movement end shaft hole and a clutch end shaft hole for the two ends of the through shaft to extend out respectively; wherein a clamping mechanism is installed on the through shaft section extending out of the hub housing through the clutch end shaft hole; at the same time, a shaft shoulder is formed on the through shaft for mounting and supporting the housing bearing located in the movement end shaft hole, and the shaft shoulder has several lead wire holes for leading the movement lead wire to the outside of the hub housing.

[0013] Furthermore, the movement described in this invention has an outer rotor and inner stator structure, with the sun gear sleeved on the through shaft and fixed to the rotor.

[0014] Furthermore, the rotor includes a rotor flywheel cover disposed around the stator and a magnet fixed on the inner wall of the rotor flywheel cover opposite to the inner stator. The rotor flywheel cover is assembled on the through shaft through a rotor bearing, and the sun gear is fixed to the outer end of the rotor flywheel cover.

[0015] Furthermore, in this invention, the extended bushing of the pinion is assembled onto the planetary shaft via several planetary bearings, which are sliding bearings. Compared to deep groove ball bearings, using sliding bearings can further reduce the radial dimension of the planetary gear, thereby facilitating an increase in the speed ratio between the large gear and the sun gear at the rotor output end, thus improving power and reducing the radial dimension of the entire hub motor housing.

[0016] Furthermore, the gear ring described in this invention is a plastic gear ring, in order to further reduce weight and reduce noise when it meshes with the metal pinion.

[0017] Furthermore, the through shaft described in this invention is a hollow cylindrical shaft used for through-mounting quick-release shafts. Quick-release shafts are a known technology, used for mounting and fixing to the side frames of a road electric-assist bicycle.

[0018] Furthermore, in this invention, the planetary gears are centrally symmetrical about the sun gear, and the number is three or more.

[0019] It should be noted that the large gear and plastic gear ring used as plastic gears in this invention can be made of any commonly used materials in the industry, such as POM (polyoxymethylene) plastic, PEEK (polyether ether ketone) plastic, and nylon plastics such as PA66 and PA46.

[0020] As for the pinion of the metal gear, and the conventional sun gear that has not been improved in this invention, its metal material is also any existing commonly used material in the industry, such as alloy steels such as 40Cr, 45Cr, and 20CrMnTi, as well as conventional copper alloys (such as brass) and aluminum alloys, etc. Its forming method can be milling, forging, cold extrusion, drawing profiles, and powder metallurgy, etc.

[0021] The advantages of this invention are:

[0022] This invention is lighter, smaller, and more compact in internal structure, while possessing higher output power and better internal structural strength, meeting the requirements for hub motors used in road electric-assist bicycles. Its specific features are as follows:

[0023] 1) The planetary gear in this invention differs from the existing one-piece manufactured plastic double gear. Its large and small gears are set separately. The large gear is made of plastic, which can reduce the overall weight of the planetary gear, while the small gear is made of metal and is fixed by an extension bushing integrally set on it. This structure allows the small gear to have its own strength while also providing a certain support strength to the large gear. This means that the large gear does not need to increase its outer diameter and thickness to increase its strength as in conventional technology. On the contrary, its outer diameter can be further reduced, thereby ensuring that it has a high speed ratio with the sun gear at the rotor output end, and thus improving the overall output power of the motor.

[0024] 2. Similarly, since the metal pinion in the planetary gear structure design of the present invention can provide sufficient support strength to the large gear, the outer diameter and thickness of the large gear can be further reduced. This is beneficial to reducing the radial and axial dimensions of the entire hub housing, thereby reducing the volume and weight of the entire hub motor.

[0025] 3. Furthermore, this invention provides recessed cavities on the outer ring end face of the clutch corresponding to each planetary gear, allowing the pinion to be embedded. Once the pinion is accommodated within these recessed cavities, the axial length occupied by the planetary gear portion within the hub housing is further reduced, thereby facilitating a reduction in the overall axial length of the hub housing, decreasing its volume, and making the internal structure more compact. This also saves production materials, reduces weight, and lowers production costs.

[0026] 4. In this invention, we also make the gear ring a plastic gear ring, which can further reduce the weight of the hub motor. The meshing of the plastic gear ring with the metal pinion can reduce noise. Similarly, the meshing of the plastic gear ring with the conventional metal sun gear at the rotor output end can also reduce noise, thereby greatly reducing the overall operating noise of the hub motor of this invention.

[0027] 5. In this invention, a sliding bearing is used on the planetary shaft to support the pinion and its extended bushing. Compared with deep groove ball bearings, the use of a sliding bearing can further reduce the radial dimension of the planetary gear, which is conducive to increasing the speed ratio between the large gear and the sun gear at the rotor output end, so as to improve power and reduce the radial dimension of the entire hub motor housing. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0029] Figure 1 This is the overall main cross-sectional view of the present invention;

[0030] Figure 2 for Figure 1 A schematic diagram of the individual three-dimensional structure of the clutch (with a planetary shaft fixed on it).

[0031] Figure 3 Front view of the clutch;

[0032] Figure 4 for Figure 1 Axial view of the left side of the central shaft.

[0033] The components are as follows: 1. Through shaft; 101. Shoulder of shaft; 101a. Lead-out cable hole; 2. Housing bearing; 3. Hub housing; 4. Clutch; 401. Outer ring; 401a. Relief cavity; 401b. Opening; 402. Inner ring; 5. Sun gear; 6. Planetary gear; 601. Large gear; 602. Small gear; 602a. Extension bushing; 7. Planetary shaft; 8. Gear ring; 9. Shaft hole at the movement end; 10. Shaft hole at the clutch end; 11. Snap-fit ​​mechanism; 12. Lead-out cable; A. Movement; 13. Stator; 14. Rotor; 14a. Rotor flywheel cover; 14b. Magnet; 15. Rotor bearing; 16. Planetary bearing; 17. Quick-release shaft; 18. Frame. Detailed Implementation

[0034] Example: The following is combined with Figures 1-4 The specific implementation of the lightweight and efficient through-shaft hub motor provided by the present invention is described below:

[0035] Like known technologies, it has a through shaft 1, a hub housing 3 mounted on the through shaft 1 at both ends via housing bearings 2, and a movement A, a planetary reduction mechanism, and a clutch 4 arranged sequentially within the hub housing 3 and along the through shaft 1, such as Figure 1 As shown from left to right. The hub housing 3 is provided with movement end shaft holes 9 for the two ends of the through shaft 1 to extend out. Figure 1 (middle left) and clutch end shaft hole 10 ( Figure 1 (Right side), where a conventional clamping mechanism 11 is installed on the section of the through shaft 1 that extends from the hub housing 3 via the clutch end shaft hole 10.

[0036] Still as Figure 1 As shown, the clutch 4 in this invention has an outer ring 401 and an inner ring 402. The inner ring 402 is fixed on the through shaft 1. The planetary reduction mechanism is composed of a sun gear 5 located on the output end of the mechanism A, three planetary gears 6, and three planetary shafts 7. The three planetary gears 6 are centrally symmetrical about the sun gear 5. In this embodiment, the mechanism A has an outer rotor 14 and an inner stator 13 structure. The sun gear 5 is sleeved on the through shaft 1 and fixed to the rotor 14. The planetary gears 6 are located on the corresponding planetary shafts 7, and the planetary shafts 7 are fixed to the outer ring 401 of the clutch 4. The sun gear 5 is connected to the gear ring 8 fixed inside the hub housing 3 via the planetary gears 6. The mechanism A has a lead cable 12.

[0037] The core improvement of this invention lies in the fact that the planetary gear 6 is a double gear, consisting of a large gear 601 and a small gear 602, which are coaxial but separately arranged. The large gear 601 is a plastic gear that meshes with the sun gear 5, while the small gear 602 is a metal gear, with an integrally formed extension sleeve 602a at its center to fix the large gear 601. In this embodiment, the large gear 601 is injection molded and pressed onto the periphery of the extension sleeve 602a. Simultaneously, combined with... Figures 1-3 As shown, in this embodiment, the outer ring 401 end face of the clutch 4 is provided with a relief cavity 401a for each planetary gear 6 to be inserted into, and the outer periphery of the outer ring 401 is provided with an opening 401b for each relief cavity 401a to allow the pinion 602 to protrude and mesh with the gear ring 8.

[0038] In this embodiment, the toothed ring 8 is a plastic toothed ring.

[0039] In this embodiment, the large gear 601, which is a plastic gear, and the aforementioned plastic gear ring are actually made of the commonly used nylon plastic PA66. The small gear 602, which is a metal gear, and the conventional sun gear 5, which is not modified in this invention, are both made of 40Cr alloy steel commonly used in the industry through powder metallurgy.

[0040] Combined Figure 1 and Figure 4 As shown, in this embodiment, a shoulder 101 is formed on the through shaft 1 for assembling and supporting the housing bearing 2 located in the shaft hole 9 at the movement end. Figure 1 (Left side of the middle) The shoulder 101 of the shaft has several lead wire holes 101a for leading the lead wire 12 of the movement A to the outside of the hub housing 3. In this embodiment, there are a total of 4 lead wire holes 101a.

[0041] Combined Figure 1 As shown, in this embodiment, the rotor 14 is composed of a rotor flywheel cover 14a located around the stator 13 and a magnet 14b fixed on the inner wall of the rotor flywheel cover 14a opposite to the inner stator 13. The rotor flywheel cover 14a is assembled on the through shaft 1 by two rotor bearings 15, and the sun gear 5 is fixed to the outer end of the rotor flywheel cover 14a.

[0042] Meanwhile, the extended bushing 602a of the pinion 602 is mounted on the planetary shaft 7 via two planetary bearings 16, and the planetary bearings 16 are sliding bearings. Compared with deep groove ball bearings, the use of sliding bearings can further reduce the radial dimension of the planetary gear 6, thereby increasing the speed ratio between the large gear 601 and the sun gear 5 at the output end of the rotor 14, so as to improve power and reduce the radial dimension of the entire hub motor housing.

[0043] In this embodiment, the through shaft 1 is a hollow cylindrical shaft used to pass through and install the quick-release shaft 17. The quick-release shaft 17 is a known technology and is used to assemble and fix it to the side frames 18 of the road electric-assist bicycle, such as... Figure 1 As shown.

[0044] The in-wheel motor of this embodiment has the following technical advantages:

[0045] 1) The planetary gear 6 in this embodiment is different from the existing one-piece manufactured plastic double gear. Its large gear 601 and small gear 602 are set separately. The large gear 601 is made of plastic gear, which can reduce the overall weight of planetary gear 6. The small gear 602 is made of metal gear and is fixed by the extended bushing 602a integrally set on it. This structure allows the small gear 602 to have its own strength while also providing a certain support strength to the large gear 601. This means that the large gear 601 does not need to increase its outer diameter and thickness to increase its strength as in conventional technology. On the contrary, its outer diameter can be further reduced, thereby ensuring that it has a high speed ratio with the sun gear 5 at the output end of the rotor 14, thereby improving the overall output power of the motor.

[0046] 2. Similarly, since the metal pinion 602 in the planetary gear 6 structure design can provide sufficient support strength to the large gear 601, the outer diameter and thickness of the large gear 601 can be further reduced. This is beneficial to reducing the radial and axial dimensions of the entire hub housing 3, thereby reducing the volume and weight of the entire hub motor.

[0047] 3. Simultaneously, in this embodiment, the outer ring 401 end face of the clutch 4 has a clearance cavity 401a corresponding to each planetary gear 6 for the pinion 602 to be inserted. After the pinion 602 is accommodated in the clearance cavity 401a, the axial length occupied by the planetary gear 6 in the inner cavity of the hub housing 3 can be further reduced, thereby facilitating the reduction of the axial length of the entire hub housing 3, reducing its volume, and making the internal structure more compact. This also saves production materials, reduces weight, and lowers production costs.

[0048] 4. In this embodiment, we also make the gear ring 8 into a plastic gear ring, which can further reduce the weight of the hub motor. The meshing of the plastic gear ring with the metal pinion 602 can reduce noise. Similarly, the meshing of the plastic gear 601 with the conventional metal sun gear 5 at the output end of the rotor 14 can also reduce noise, thereby greatly reducing the overall operating noise of the hub motor of the present invention.

[0049] Of course, the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All modifications made according to the spirit and essence of the main technical solution of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A lightweight and efficient through-shaft hub motor, comprising a through shaft (1), a hub housing (3) mounted on the through shaft (1) at both ends via housing bearings (2), and a core (A), a planetary reduction mechanism, and a clutch (4) disposed within the hub housing (3) and sequentially assembled along the through shaft (1). The clutch (4) comprises an outer ring (401) and an inner ring (402), the inner ring (402) being fixed on the through shaft (1). The planetary reduction mechanism comprises a sun gear (5) disposed on the output end of the core (A) and a plurality of planetary gears (6), the planetary gears (6) being disposed on a planetary shaft (7), and the planetary shaft (7) being fixed to the outer ring (401) of the clutch (4). The sun gear (5) is connected to a gear ring (8) fixed inside the hub housing (3) via the planetary gears (6). The planetary gear (6) is a double gear, including a large gear (601) and a small gear (602) that are coaxial but separate. The large gear (601) is a plastic gear that meshes with the sun gear (5), while the small gear (602) is a metal gear that meshes with the gear ring (8). The small gear (602) has an integral extension bushing (602a) at its center to fix the large gear (601). The outer ring (401) end face of the clutch (4) is provided with a relief cavity (401a) for each planetary gear (6) to be inserted into its pinion (602), and the outer circumference of the outer ring (401) is provided with an opening (401b) for each relief cavity (401a) to allow the outer peripheral teeth of the pinion (602) to protrude and mesh with the gear ring (8); The toothed ring (8) is a plastic toothed ring.

2. The lightweight and efficient through-shaft hub motor according to claim 1, characterized in that... The large gear (601) is injection molded and pressed onto the periphery of the extension sleeve (602a) of the small gear (602), or the large gear (601) is fitted into the periphery of the extension sleeve (602a) of the small gear (602) through a keyway structure.

3. The lightweight and efficient through-shaft hub motor according to claim 1, characterized in that... The hub housing (3) is provided with a mechanism end shaft hole (9) and a clutch end shaft hole (10) for the two ends of the through shaft (1) to extend out; a clamping mechanism (11) is installed on the section of the through shaft (1) that extends out of the hub housing (3) through the clutch end shaft hole (10); at the same time, a shoulder (101) is formed on the through shaft (1) for mounting and supporting the housing bearing (2) located in the mechanism end shaft hole (9). Several lead wire holes (101a) are opened on the shoulder (101) for leading out the lead wire (12) of the mechanism (A) to the outside of the hub housing (3).

4. A lightweight and efficient through-shaft hub motor according to claim 1, characterized in that... The mechanism (A) is an outer rotor (14) and inner stator (13) structure, with the sun gear (5) sleeved on the through shaft (1) and fixed together with the rotor (14).

5. A lightweight and efficient through-shaft hub motor according to claim 4, characterized in that... The rotor (14) includes a rotor flywheel cover (14a) located around the stator (13) and a magnet (14b) fixed on the inner wall of the rotor flywheel cover (14a) opposite to the inner stator (13). The rotor flywheel cover (14a) is mounted on the through shaft (1) via a rotor bearing (15). The sun gear (5) is fixed to the outer end of the rotor flywheel cover (14a).

6. A lightweight and efficient through-shaft hub motor according to claim 1, characterized in that... The extension sleeve (602a) of the pinion (602) is mounted on the planetary shaft (7) by a number of planetary bearings (16), which are sliding bearings.

7. A lightweight and efficient through-shaft hub motor according to claim 1, characterized in that... The through shaft (1) is a hollow cylindrical shaft used to pass through and install the quick-release shaft (17).

8. A lightweight and efficient through-shaft hub motor according to claim 1, characterized in that... The planetary gears (6) are centrally symmetrical about the sun gear (5), and there are more than 3 of them.

Images