Middle driving device of moped

Abstract

The utility model discloses a middle driving device of a moped, which comprises a middle motor and a pedal mechanism, and the middle motor is provided with a motor casing, a middle shaft, a motor part and a torque output sleeve; the pedal mechanism is provided with two cranks connected with the two ends of the middle shaft. The torque output sleeve is sleeved on the middle shaft; a worm and gear assembly is installed in the motor shell. The pedal mechanism and the motor part can transmit torque to the torque output sleeve through the middle shaft and the worm and gear assembly respectively. The worm and gear assembly comprises a worm connected with the motor part and a worm gear connected with the torque output sleeve, and a clutch mechanism is arranged between the worm gear and the torque output sleeve; the clutch mechanism comprises a plurality of clutch units arranged around the torque output sleeve in a scattered mode and further comprises an elastic unit, and the elastic unit can promote the clutch mechanism to be disengaged when the rotating speed of the worm gear is not higher than the rotating speed of the torque output sleeve. Therefore, the clutch mechanism has higher response speed, and the influence of the worm and gear mechanism on the rotating speed of the torque output sleeve is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of power-assisted bicycles, in particular to a mid-mounted driving device of a power-assisted bicycle. Background Art

[0002] The bicycle's mid-mounted power-assisted drive system represents an advanced electric-assist technology. Using intelligent algorithms, the mid-mounted motor synchronizes with the rider's movements, delivering instantaneous power response. This significantly enhances the convenience and enjoyment of cycling, whether in urban commuting or outdoor adventures. Compared to traditional external motors, the mid-mounted motor offers a more compact and aesthetically pleasing solution. The design advantage of this motor lies in its ability to more evenly distribute power, optimizing riding dynamics and minimizing interference with the bicycle's inherent structure. With rising environmental awareness and increasing urban traffic pressures, mid-mounted motor bicycles are becoming a growing choice for green transportation. They represent not only a lifestyle but also an exploration and practice of future sustainable transportation.

[0003] To improve the compactness of mid-mounted motors, some existing mid-mounted motors use a worm gear with a high transmission ratio as a reduction mechanism. For example, Patent CN 115789225 A discloses a worm gear reduction mid-mounted motor. In this motor, a one-way clutch is located between the worm gear and the torque output sleeve. Due to the reverse self-locking nature of the worm gear, the one-way clutch may not disengage in time, causing the worm gear to drag the torque output sleeve and create a braking effect. Therefore, it is necessary to improve the response speed of the one-way clutch to address this issue. Utility Model Content

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the utility model provides a mid-drive device for a power-assisted bicycle with a high clutch response speed and the ability to promptly disconnect the connection between the worm gear and the torque output sleeve.

[0005] Technical solution: To achieve the above-mentioned purpose, the mid-mounted drive device of the power-assisted bicycle of the present invention includes a mid-mounted motor and a pedal mechanism. The mid-mounted motor has a motor housing, a central shaft, a motor part, and a torque output sleeve; the pedal mechanism has two cranks connected to the two ends of the central shaft; the torque output sleeve is sleeved on the central shaft;

[0006] A worm gear assembly is installed in the motor housing; the pedal mechanism and the motor part are capable of transmitting torque to the torque output sleeve via the central shaft and the worm gear assembly respectively;

[0007] The worm gear assembly includes a worm connected to the motor part and a worm wheel connected to the torque output sleeve, and a clutch mechanism is provided between the worm wheel and the torque output sleeve;

[0008] The clutch mechanism includes a plurality of clutch units dispersedly arranged around the torque output sleeve, and also includes an elastic unit, which can cause the clutch mechanism to disengage when the rotation speed of the worm gear is not higher than the rotation speed of the torque output sleeve.

[0009] In one embodiment, the clutch unit is a roller; the clutch mechanism further includes a separation bracket for separating all of the rollers and an outer shell disposed around all of the rollers; one of the outer surface of the torque output sleeve and the inner surface of the outer shell has a tooth portion corresponding to each of the rollers, and the other is a circumferential surface, with a space of varying width formed between one tooth surface of the tooth portion and the circumferential surface; the clutch mechanism further includes a compression spring acting on the separation bracket, the compression spring causing the separation bracket to rotate relative to the torque output sleeve. When the worm gear rotates in the forward direction and the worm gear speed is greater than the speed of the torque output sleeve, the roller moves toward the narrower side of the irregular space between the tooth surface and the circumferential surface until the torque output sleeve and the outer shell are fully engaged, at which point the power of the motor can be transmitted to the torque output sleeve; when the worm gear speed is less than the speed of the torque output sleeve, the compression spring drives the separation bracket to rotate actively, and the separation bracket pushes the roller toward the wider side of the irregular space, quickly releasing the engagement, allowing the torque output sleeve and the outer shell to operate separately.

[0010] In a second solution, the clutch unit is a wedge block having an arc surface and an obtuse angle surface; and the elastic unit is an annular spring acting on all the wedge blocks.

[0011] Furthermore, the central drive device also includes a torque detection mechanism; a torque deformation sleeve is also sleeved on the central shaft, the two ends of the torque deformation sleeve are respectively connected to the central shaft and one end of the torque output sleeve, and the other end of the torque output sleeve extends out of the motor housing and is connected to the transmission component; the torque detection mechanism is installed around the torque deformation sleeve.

[0012] Furthermore, the torque-deforming sleeve is connected to the central shaft via a one-way clutch. This ensures that the one-way clutch engages only when the torque-deforming sleeve is outputting torque to the torque output sleeve; otherwise, the one-way clutch disengages, ensuring that the states of the torque output sleeve and the torque-deforming sleeve do not affect each other. The structure of the one-way clutch can be found in the clutch mechanism and will not be further described here.

[0013] Furthermore, the motor is mounted outside the motor housing, and the motor's output shaft extends into the motor housing and connects to the worm. The worm and output shaft can be integrally formed, or they can be separately machined and later assembled and secured. This approach reduces assembly difficulty.

[0014] Furthermore, both ends of the central shaft have spline parts connected to the crank, and each spline part has a radial hole; the end of the crank has a spline hole that matches the spline part, and the side walls of the spline hole have a through groove, and the two sides of the through groove are connected by screws; a stop plate connected to the crank is installed in the through groove, and the stop plate has an embedded part embedded in the radial hole.

[0015] Furthermore, the stop plate is provided with two positioning holes, and the crank is provided with two screws passing through the two positioning holes respectively.

[0016] By providing a stop plate, the embedded portion can keep the crank from falling relative to the middle axis after the screw is loosened, ensuring safety and avoiding the trouble of being unable to ride after the crank falls.

[0017] Furthermore, the positions of the two radial holes on the central shaft differ by 180 degrees, so as to meet the installation requirements of the two cranks respectively.

[0018] Furthermore, the mid-mounted drive device further includes an outer cover arranged around the mid-mounted motor.

[0019] The torque detection mechanism includes a strain gauge fixed to the torque deformation sleeve and a first circuit board, the strain gauge being connected to the first circuit board. The torque detection mechanism also includes a second circuit board, which is capable of wireless communication and wireless power transmission with the first circuit board. Specifically, both circuit boards are annular and have annular coils. Wireless power transmission and communication between the two circuit boards are achieved through the principle of electromagnetic induction. This technology is prior art and will not be elaborated on here.

[0020] Furthermore, the motor housing includes a main housing with a mounting cavity therein; the motor housing also includes a first end cap located at one end of the mounting cavity and a second end cap located outside the first end cap; the second end cap and the first end cap have mutually mating conical surfaces to maintain concentricity between the two end caps. The first end cap is mounted with a bearing that supports the torque deformation sleeve, and the second end cap is mounted with a bearing that supports the central shaft. Providing two end caps facilitates assembly and improves efficiency.

[0021] Furthermore, a third end cover is mounted on the main housing, and a space for accommodating a control circuit board is formed between the third end cover and the outer wall of the main housing.

[0022] Furthermore, the distance between the axis centers of the worm and the worm wheel is 45 mm.

[0023] Beneficial effects: The mid-mounted drive device of the power-assisted bicycle of the present invention has the following beneficial effects:

[0024] (1) By changing the structure of the clutch mechanism, the clutch mechanism has a faster response speed. Once the motor part does not meet the conditions for outputting torque to the torque output sleeve, the elastic unit can push the separation bracket to rotate so that the clutch mechanism can be quickly disengaged, preventing the motor part from slowing down the speed of the torque output sleeve. Since the worm gear mechanism has a reverse self-locking function, the structure of the clutch mechanism can effectively prevent the worm gear mechanism from affecting the speed of the torque output sleeve.

[0025] (2) By separately providing the torque output sleeve and the torque deformation sleeve, the difficulty of processing and assembly can be reduced, and the deformation of the torque output sleeve can accurately reflect the torque transmitted by the central axis to the torque output sleeve, which can make the detection accurate.

[0026] (3) By providing a stop plate, the embedded portion can keep the crank from falling relative to the center axis after the screw is loosened, thereby ensuring safety and avoiding the inconvenience of being unable to ride after the crank falls. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of the mid-mounted drive device of the power-assisted vehicle in the first embodiment;

[0028] Figure 2 It is a cross-sectional structural diagram of the mid-mounted drive device of the power-assisted vehicle in the first embodiment;

[0029] Figure 3 is a first cross-sectional structural diagram of the clutch mechanism in the first embodiment;

[0030] Figure 4 is a second cross-sectional structural diagram of the clutch mechanism in the first embodiment;

[0031] Figure 5 This is a diagram showing the connection structure between the middle shaft and the crank in the first embodiment;

[0032] Figure 6 It is a structural diagram of the clutch mechanism in the second embodiment.

[0033] In the figure: A-mid-mounted motor; B-pedal mechanism; C-outer cover; 1-central shaft; 1a-spline part; 1b-radial hole; 2-crank; 3-motor housing; 31-main housing; 32-first end cover; 33-second end cover; 34-third end cover; 4-motor part; 5-worm gear assembly; 51-worm; 52-worm wheel; 6-torque output sleeve; 7-clutch mechanism; 71-roller; 72-partition bracket; 73-outer housing; 74-compression spring; 75-wedge block; 76-annular spring; 8-torque detection mechanism; 81-strain gauge; 82-first circuit board; 83-second circuit board; 9-torque deformation sleeve; 10-transmission component; 11-screw; 12-stop plate; 12a-embedded part; 12b-positioning hole; 13-one-way clutch. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings.

[0035] Example 1

[0036] like Figure 1-Figure 2 The mid-mounted driving device of the power-assisted bicycle shown includes a mid-mounted motor A and a pedal mechanism B, and also includes an outer cover C arranged around the mid-mounted motor A.

[0037] The mid-mounted motor A comprises a motor housing 3, a central shaft 1, a motor portion 4, and a torque output sleeve 6. The pedal mechanism B comprises two cranks 2 connected to the ends of the central shaft 1. The torque output sleeve 6 is sleeved onto the central shaft 1. A worm gear assembly 5 is mounted within the motor housing 3. The pedal mechanism B and the motor portion 4 are capable of transmitting torque to the torque output sleeve 6 via the central shaft 1 and the worm gear assembly 5, respectively. The central shaft 1 preferably has a length of 133 mm. The diameter of the motor portion 4 is no greater than 66 mm.

[0038] The worm gear assembly 5 includes a worm 51 connected to the motor part 4 and a worm wheel 52 connected to the torque output sleeve 6, and a clutch mechanism 7 is provided between the worm wheel 52 and the torque output sleeve 6. The distance between the axis of the worm 51 and the worm wheel 52 is preferably 45 mm. The motor part 4 is mounted on the outside of the motor housing 3, and the output shaft of the motor part 4 extends into the motor housing 3 and is connected to the worm 51. The worm 51 and the output shaft can be integrally formed, or they can be processed separately and assembled and fixed later. In this way, the difficulty of assembly can be reduced.

[0039] like Figure 3-4As shown, the clutch mechanism 7 includes a plurality of rollers 71 dispersedly arranged around the torque output sleeve 6, a separation bracket 72 for separating all of the rollers 71, and an outer shell 73 disposed around all of the rollers 71. One of the outer surface of the torque output sleeve 6 and the inner surface of the outer shell 73 has a tooth portion a corresponding to each of the rollers 71, and the other is a circumferential surface. A space of varying width is formed between one tooth surface of the tooth portion a and the circumferential surface. The clutch mechanism 7 also includes a compression spring 74 acting on the separation bracket 72. The compression spring 74 causes the separation bracket 72 to rotate relative to the torque output sleeve 6. This rotational movement can cause the clutch mechanism 7 to switch to a disengaged state. Specifically, the separation bracket 72 has a groove for accommodating the compression spring 74, and the torque output sleeve 6 has an intrusion extending into the groove, with the ends of the compression spring respectively abutting against the groove wall and the intrusion.

[0040] By adopting the above structure, by changing the structure of the clutch mechanism 7, the clutch mechanism 7 has a faster response speed. Once the motor part 4 does not meet the conditions for outputting torque to the torque output sleeve 6, the compression spring 74 can push the separation bracket 72 to rotate so that the clutch mechanism 7 can be quickly disengaged, preventing the motor part 4 from slowing down the speed of the torque output sleeve 6. Specifically, when the worm gear 52 rotates in the forward direction and the speed of the worm gear 52 is greater than the speed of the torque output sleeve 6, the roller 71 moves toward the narrower side of the irregular space between the tooth surface and the circumferential surface until the torque output sleeve 6 and the outer shell 73 are completely engaged. At this time, the power of the motor part 4 can be transmitted to the torque output sleeve 6; when the speed of the worm gear 52 is less than the speed of the torque output sleeve 6, the compression spring 74 pushes the separation bracket 72 to rotate actively, and the separation bracket 72 pushes the roller 71 toward the wider side of the irregular space, which can quickly release the engagement, allowing the torque output sleeve 6 and the outer shell 73 to operate separately.

[0041] The central drive device also includes a torque detection mechanism 8; a torque deformation sleeve 9 is also sleeved on the central shaft 1, and the two ends of the torque deformation sleeve 9 are respectively connected to the central shaft 1 and one end of the torque output sleeve 6, and the other end of the torque output sleeve 6 extends out of the motor housing 3 and is connected to the transmission component 10; the torque detection mechanism 8 is installed around the torque deformation sleeve 9.

[0042] By adopting the above structure, by separately arranging the torque output sleeve 6 and the torque deformation sleeve 9, the difficulty of processing and assembly can be reduced, and the deformation amount of the torque output sleeve 6 can accurately reflect the torque transmitted from the central shaft 1 to the torque output sleeve 6, which can make the detection accurate.

[0043] Specifically, the torque-deforming sleeve 9 is connected to the central shaft 1 via a one-way clutch 13. This ensures that the one-way clutch engages only when the torque-deforming sleeve 9 is outputting torque to the torque output sleeve 6; otherwise, the one-way clutch disengages, ensuring that the states of the torque output sleeve 6 and the torque-deforming sleeve 9 do not affect each other. The structure of the one-way clutch can be found in the clutch mechanism 7 and will not be further described here.

[0044] The torque detection mechanism 8 includes a strain gauge 81 fixed to the torque deformation sleeve 9 and a first circuit board 82. The strain gauge 81 is connected to the first circuit board 82. The torque detection mechanism 8 also includes a second circuit board 83. The second circuit board 83 and the first circuit board 82 are capable of wireless communication and wireless power transmission. Specifically, both circuit boards are annular and have annular coils. Wireless power transmission and communication between them are achieved through the principle of electromagnetic induction. This technology is existing and will not be elaborated on here.

[0045] like Figure 5 As shown, both ends of the central shaft 1 have a spline portion 1a connected to the crank 2, and each of the spline portions 1a has a radial hole 1b; the end of the crank 2 has a spline hole matching the spline portion 1a, and the side walls of the spline hole have a through groove 2a, and the two sides of the through groove 2a are connected by a screw 11; a stop plate 12 connected to the crank 2 is installed in the through groove 2a, and the stop plate 12 has an embedded portion 12a embedded in the radial hole 1b.

[0046] Specifically, the stop plate 12 further has two positioning holes 12 b , and the crank 2 is mounted with two screws 11 passing through the two positioning holes 12 b respectively.

[0047] By providing the stop plate 12, after the screw 11 is loosened, the embedded portion 12a can keep the crank 2 from falling relative to the central axis 1, ensuring safety and avoiding the trouble of being unable to ride after the crank 2 falls.

[0048] The positions of the two radial holes 1 b on the central shaft 1 are 180 degrees apart, so as to meet the installation requirements of the two cranks 2 respectively.

[0049] The motor housing 3 includes a main housing 31 with a mounting cavity therein. The motor housing 3 also includes a first end cap 32 located at one end of the mounting cavity and a second end cap 33 located outside the first end cap 32. The second end cap 33 and the first end cap 32 have mating conical surfaces to maintain concentricity between the two end caps. The first end cap 32 is mounted with a bearing that supports the torque deformation sleeve 9, while the second end cap 33 is mounted with a bearing that supports the central shaft 1. The provision of two end caps facilitates assembly and improves efficiency.

[0050] The main housing 31 is further provided with a third end cover 34, and a space for accommodating a control circuit board is formed between the third end cover 34 and the outer wall of the main housing 31. The above structure facilitates storage and disassembly of the control circuit board.

[0051] Example 2

[0052] In this embodiment, the overall structure of the mid-mounted drive device of the power-assisted bicycle is consistent with that in the first embodiment, with the only difference being the structure of the clutch mechanism 7 .

[0053] In this embodiment, Figure 6 As shown, the clutch unit is a wedge 75 having an arc surface and an obtuse-angled surface. The obtuse-angled surface is asymmetrical, with one surface closer to the center of the circle, called the proximal surface, and the other farther from the center, called the distal surface. The elastic unit is an annular spring 76 that acts on all of the wedges 75. The wedges 75 have a notch centered relative to the obtuse-angled surface, and the annular spring 76 is embedded in the notch of each wedge 75.

[0054] With the above structure, when the rotation speed of the worm gear 52 is greater than the rotation speed of the torque output sleeve 6, the distal surface of the wedge 75 engages the inner wall of the worm gear 52, achieving engagement between the torque output sleeve 6 and the worm gear 52. When the rotation speed of the worm gear 52 is less than or equal to the rotation speed of the torque output sleeve 6, the clutch mechanism 7 is quickly disengaged.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A mid-mounted drive device for a power-assisted vehicle, characterized in that: It comprises a central motor (A) and a pedal mechanism (B), wherein the central motor (A) comprises a motor housing (3), a central shaft (1), a motor part (4) and a torque output sleeve (6); the pedal mechanism (B) comprises two cranks (2) connected to both ends of the central shaft (1); the torque output sleeve (6) is sleeved on the central shaft (1); A worm gear assembly (5) is installed in the motor housing (3); the pedal mechanism (B) and the motor part (4) are capable of transmitting torque to the torque output sleeve (6) via the central shaft (1) and the worm gear assembly (5) respectively; The worm gear assembly (5) comprises a worm (51) connected to the motor part (4) and a worm wheel (52) connected to the torque output sleeve (6), and a clutch mechanism (7) is provided between the worm wheel (52) and the torque output sleeve (6); The clutch mechanism (7) includes a plurality of clutch units dispersedly arranged around the torque output sleeve (6), and also includes an elastic unit, wherein the elastic unit is capable of causing the clutch mechanism (7) to disengage when the rotation speed of the worm gear (52) is not higher than the rotation speed of the torque output sleeve (6).

2. The mid-mounted drive device of the power-assisted vehicle according to claim 1, characterized in that: The clutch unit is a roller (71); the clutch mechanism (7) further includes a separation bracket (72) for separating all the rollers (71) and an outer shell (73) arranged around all the rollers (71); one of the outer surface of the torque output sleeve (6) and the inner surface of the outer shell (73) has a tooth portion (a) corresponding to each roller (71), and the other is a circumferential surface, and a space of varying width is formed between one tooth surface of the tooth portion (a) and the circumferential surface; the clutch mechanism (7) further includes a compression spring (74) acting on the separation bracket (72), and the compression spring (74) enables the separation bracket (72) to have a rotational motion tendency relative to the torque output sleeve (6).

3. The mid-mounted drive device of the power-assisted vehicle according to claim 1, characterized in that: The clutch unit is a wedge block (75), and the wedge block (75) has an arc surface and an obtuse angle surface; the elastic unit is an annular spring (76) acting on all the wedge blocks (75).

4. The mid-mounted drive device of the power-assisted vehicle according to claim 1, characterized in that: The central drive device further comprises a torque detection mechanism (8); a torque deformation sleeve (9) is sleeved on the central shaft (1); two ends of the torque deformation sleeve (9) are respectively connected to the central shaft (1) and one end of the torque output sleeve (6); the other end of the torque output sleeve (6) extends out of the motor housing (3) and is connected to a transmission component (10); the torque detection mechanism (8) is installed around the torque deformation sleeve (9).

5. The mid-mounted drive device of the power-assisted vehicle according to claim 4, characterized in that: The torque deformation sleeve (9) and the central shaft (1) are connected via a one-way clutch (13).

6. The mid-mounted drive device of the power-assisted vehicle according to claim 1, characterized in that: Both ends of the central shaft (1) have spline parts (1a) connected to the crank (2), and each spline part (1a) has a radial hole (1b); the end of the crank (2) has a spline hole matching the spline part (1a), and the side walls of the spline hole have a through groove (2a), and the two sides of the through groove (2a) are connected by screws (11); a stop plate (12) connected to the crank (2) is installed in the through groove (2a), and the stop plate (12) has an embedded part (12a) embedded in the radial hole (1b).

7. The mid-mounted drive device of the power-assisted vehicle according to claim 6, characterized in that: The stop plate (12) is further provided with two positioning holes (12b), and the crank (2) is provided with two screws (11) passing through the two positioning holes (12b) respectively.

8. The mid-mounted drive device of the power-assisted vehicle according to claim 1, characterized in that: The distance between the axis centers of the worm (51) and the worm wheel (52) is 45 mm.

9. The mid-mounted drive device of the power-assisted vehicle according to claim 1, characterized in that: The motor housing (3) comprises a main housing (31), wherein the main housing (31) has an installation cavity; the motor housing (3) further comprises a first end cover (32) located at one end of the installation cavity and a second end cover (33) located outside the first end cover (32); the second end cover (33) and the first end cover (32) have mutually matching conical surfaces.

10. The mid-mounted drive device of the power-assisted vehicle according to claim 9, characterized in that: A third end cover (34) is also mounted on the main housing (31), and an accommodation space capable of accommodating a control circuit board is formed between the third end cover (34) and the outer wall of the main housing (31).

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