Stepless speed change device of middle motor

Abstract

The utility model belongs to the technical field of bicycles, and particularly relates to a mid-motor stepless speed change device which comprises a planet row assembly, and the planet row assembly comprises a gear ring, a sun gear located in the center of the gear ring, a plurality of planet gears located between the gear ring and the sun gear and a planet carrier. The device is characterized by further comprising a middle shaft and a motor, the center shaft penetrates through the center of the sun gear and is fixedly connected with the gear ring, the output end of the motor is directly or indirectly connected with the sun gear, and the center shaft and the motor converge power and output the power to the wheels through the planet row assembly. The motor and the continuously variable transmission are integrated and arranged at the position of the center shaft of the bicycle, a traditional cone pulley type transmission is omitted, the structure is compact, the transmission efficiency is high, the mass center of the whole bicycle is more concentrated to the position of the center shaft, and the problem that the mass center is unbalanced in the prior art is solved.

Description

Technical Field

[0001] This utility model belongs to the field of bicycle technology, specifically, it relates to a continuously variable transmission device with a mid-mounted motor. Background Technology

[0002] Placing the motor at the bottom bracket of an e-bike is beneficial for the overall balance of the bike, but the bottom bracket area has limited space and the design of a bottom bracket motor is difficult, so it is generally used in the high-end bike market. Existing technology usually uses a mid-mounted motor plus a rear axle derailleur architecture. This structure is complex and has low transmission efficiency; the rear derailleur increases the mass of the rear wheel area, causing an imbalance in the overall center of gravity of the bike.

[0003] For example, patent application number 201910548883.2, entitled "A Coaxial Mid-Motor for an Assisted Bicycle and an Assisted Bicycle," describes a technical solution that uses a planetary gear set to coaxially arrange the motor and reduction gears. The entire bicycle adopts a mid-mounted motor and rear derailleur architecture, with power output from the mid-shaft to the rear derailleur via chain drive. Although the overall structure is compact, the planetary gear set ring gear is locked. The motor power is reduced and amplified by the planetary gear set before being combined with the power from the sprocket at the mid-shaft. The planetary gear set only has a reduction function, not a gear shifting function. Furthermore, the derailleur is located on the rear axle, resulting in an unbalanced center of gravity and low transmission efficiency.

[0004] Therefore, a continuously variable transmission device for a mid-mounted motor is needed to solve the above-mentioned technical problems. Utility Model Content

[0005] This utility model addresses the shortcomings of existing technologies by proposing a mid-mounted motor continuously variable transmission device that integrates the motor and the continuously variable transmission and positions it at the bottom bracket of the bicycle. This eliminates the need for the traditional cassette-type transmission, resulting in a compact structure, high transmission efficiency, and a more concentrated center of gravity at the bottom bracket, thus solving the problem of unbalanced center of gravity in existing technologies.

[0006] To achieve the technical objective of this utility model, the following technical solution will be adopted:

[0007] A continuously variable transmission device for a mid-mounted motor includes a planetary gear assembly, wherein the planetary gear assembly includes a ring gear, a sun gear located at the center of the ring gear, a plurality of planet gears located between the ring gear and the sun gear, and a planet carrier; characterized in that it further includes a central shaft and a motor;

[0008] The central shaft passes through the center of the sun gear and is fixedly connected to the gear ring. The output end of the motor is directly or indirectly connected to the sun gear. The central shaft and the motor combine and output power to the wheels through the planetary gear assembly.

[0009] Furthermore, it also includes a one-way clutch; one end of the one-way clutch is connected to the central shaft, and the other end is connected to the sun gear of the planetary gear assembly.

[0010] Furthermore, when the rotational speed of the intermediate shaft is greater than that of the sun gear, the one-way clutch is engaged, the rotational speeds of the intermediate shaft and the sun gear are the same, and the speed ratio is 1; when the rotational speed of the intermediate shaft is less than that of the sun gear, the one-way clutch is disengaged, and the input power of the planetary gear assembly is split.

[0011] Furthermore, the input power shunt principle of the planetary gear set is determined by the following formula:

[0012] P S +P Z =P C

[0013] In the formula: P S P Z P C These represent the power of the motor, the central shaft, and the planetary carrier, respectively.

[0014] Furthermore, the assist ratio of the continuously variable transmission (CVT) for the mid-mounted motor is determined by the following formula:

[0015]

[0016] In the formula: λ represents the assist ratio; P S P Z These represent the power of the motor and the central shaft, respectively; T S T Z These represent the torques of the sun gear and the central axle, respectively; n S n Z These represent the rotational speeds of the sun gear and the central axis, respectively; n MG i1 represents the speed of the motor; k represents the speed ratio of the planetary gear set; i1 represents the speed ratio between the motor and the sun gear.

[0017] Furthermore, the rotational speed relationship between the central axle, the motor, and the wheels is determined by the following formula:

[0018] n MG / i1+k*n Z = (1+k)*i2*n W

[0019] Where: n MG i1 represents the speed of the motor; i1 represents the speed ratio between the motor and the sun gear; k represents the speed ratio of the planetary gear set; n Z i1 represents the rotational speed of the central shaft; i2 represents the speed ratio between the planetary carrier and the output gear; n W This indicates the rotational speed of the wheel.

[0020] Furthermore, the mid-mounted motor continuously variable transmission device has at least the following operating modes: starting mode, assist mode, power generation mode, input power splitting mode after starting, pure human riding mode, and limp mode.

[0021] Furthermore, the one-way clutch employs an overrunning clutch.

[0022] The beneficial effects of this utility model are:

[0023] First, this utility model integrates the bottom bracket and continuously variable transmission (CVT) and arranges them at the bottom bracket position of the bicycle. The planetary gear assembly couples the power of the bottom bracket (pedal) and the motor assembly to the wheel. Since the speed of the bottom bracket and the speed of the motor assembly jointly determine the speed of the wheel, the continuously variable transmission function is realized. The traditional tower wheel type transmission is eliminated. The structure is compact, the transmission efficiency is high, and the center of gravity of the whole vehicle is more concentrated at the bottom bracket, which solves the problem of unbalanced center of gravity in the prior art.

[0024] Secondly, in the preferred implementation, this utility model achieves unidirectional power transmission through the connection arrangement of a one-way clutch. Power can only be transmitted from the central shaft to the sun gear, and cannot be transmitted from the sun gear to the central shaft. It also achieves power disconnection and engagement. When the one-way clutch is engaged, it locks with the planetary gear set, making the central shaft, sun gear, and wheel rotate at the same speed. Power is output to the wheel through the planetary gear set. The starting process does not rely on the power assist system, and the starting response is fast. When the one-way clutch is in the overrunning disengagement state, the planetary gear set enters the input power splitting mode. The power of the central shaft and the motor assembly is combined and output to the wheel through the planetary carrier, driving the wheel to move.

[0025] Third, in the preferred implementation, the assist ratio λ of this utility model is related to the speed ratio of the motor and the central shaft. By adjusting the speed of the motor, the assist ratio λ that meets the needs of different working conditions can be adjusted.

[0026] Fourth, in the preferred implementation, this utility model achieves the input power shunt function through a planetary gear set assembly. The input power shunt principle is P S +P Z =P C P S P Z P C These represent the power of the motor (or sun gear), the central shaft (or gear ring), and the wheels (or planetary carrier), respectively.

[0027] Fifth, in the preferred implementation, this utility model has at least a starting mode, an assist mode, a power generation mode, an input power splitting mode after starting, a pure human riding mode, and a limp mode to meet the riding needs of different working conditions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the continuously variable transmission device for the mid-mounted motor in Embodiment 1 of this utility model;

[0029] Figure 2This is a schematic diagram of the structure of the continuously variable transmission device for the mid-mounted motor in Embodiment 2 of this utility model;

[0030] Figure 3 This is a vector diagram of the assist working condition of the continuously variable transmission device with a mid-mounted motor in Embodiment 3 of the utility model;

[0031] Figure 4 This is a vector diagram of the power generation operation of the mid-mounted motor continuously variable transmission device in Embodiment 1 of this utility model;

[0032] Figure 5 This is a vector diagram of the starting condition of the continuously variable transmission device with a mid-mounted motor in Embodiment 3 of this utility model.

[0033] Among them, 1-central shaft; 2-planetary gear assembly; 20-ring gear; 21-planetary gear; 22-planet carrier; 23-sun gear; 3-motor assembly; 30-motor; 31-motor first gear; 32-motor second gear; 4-output wheel; 5-housing; 6-one-way clutch; A-wheel. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solutions of this application, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0035] The directional terms such as above, below, left, right, front, and back used in this application are based on the positional relationships shown in the attached drawings. Different attached drawings may result in different positional relationships, therefore they should not be interpreted as limitations on the scope of protection.

[0036] In this application, the terms "installation," "connection," "interlocking," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, or a connection that allows communication between components. They can also refer to a direct connection or an indirect connection through an intermediate medium. They can refer to the internal connection of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0037] Example 1

[0038] Refer to the instruction manual appendix Figure 1A continuously variable transmission (CVT) device with a mid-mounted motor includes a central shaft 1, a planetary gear set 2, and a motor. The planetary gear set 2 includes a ring gear, a sun gear located at the center of the ring gear, multiple planet gears located between the ring gear and the sun gear, and a planet carrier. The central shaft 1 passes through the center of the sun gear and is fixedly connected to the ring gear, used to transmit torque to the planet carrier through the ring gear and planet gears; the output end of the motor is directly or indirectly connected to the sun gear, used to transmit torque to the planet carrier through the sun gear, or to receive torque transmitted from the central shaft to the planet carrier through the sun gear; the planet carrier is connected to the bicycle wheel A, used to transmit the torque of the planet carrier to the wheel A, and the wheel A receives the torque transmitted to the planet carrier by the motor and the central shaft 1, that is, the central shaft 1 and the motor combine power to the wheel A through the planetary gear set 2.

[0039] The structure of this embodiment integrates the bottom bracket 1 and the continuously variable transmission (CVT) and is located at the bottom bracket position of the bicycle. The planetary gear set 2 couples the power of the bottom bracket 1 and the motor to the wheel A. Since the rotational speed of the bottom bracket 1 and the rotational speed of the motor set 3 jointly determine the rotational speed of the wheel A, the continuously variable transmission function is realized. The traditional tower wheel type gearbox is eliminated, resulting in a compact structure, high transmission efficiency, and a more concentrated center of gravity of the whole vehicle at the bottom bracket, thus solving the problem of center of gravity imbalance in the prior art.

[0040] Example 2

[0041] Refer to the instruction manual appendix Figure 2 This embodiment includes all the structures of Embodiment 1, and also includes a housing 5 and a one-way clutch 6. The central shaft 1 passes through both sides of the housing 5 and is rotatably connected to the housing 5 via bearings. The planetary gear assembly 2, the motor and the one-way clutch 6 are all located inside the housing 5.

[0042] The one-way clutch 6 is an overrunning clutch, with one end connected to the central shaft 1 and the other end connected to the sun gear of the planetary gear assembly 2, so as to... Figure 2 Taking the illustrated state as an example, the one-way clutch 6 is connected to the sun gear of the planetary gear assembly 2. When the speed of the intermediate shaft 1 is greater than the speed of the sun gear, the one-way clutch 6 is in the engaged state; when the speed of the intermediate shaft 1 is less than the speed of the sun gear, the one-way clutch 6 is in the overrunning disengaged state.

[0043] Using the structure of this embodiment, the one-way clutch 6 enables unidirectional power transmission. Power can only be transmitted from the central shaft 1 to the sun gear, but not from the sun gear to the central shaft 1. It also enables power disconnection and engagement. When the one-way clutch 6 is engaged, it locks with the planetary gear set 2, making the central shaft 1, sun gear, and planetary carrier rotate at the same speed with a speed ratio of 1. When the one-way clutch 6 is in the overrunning disengagement state, the planetary gear set 2 enters the input power splitting mode. The power from the central shaft 1 and the motor is combined and output to wheel A via the planetary carrier, driving wheel A to move.

[0044] Example 3

[0045] Based on Embodiment 1 or 2, the planetary gear assembly 2 in this embodiment includes a gear ring, a sun gear located at the center of the gear ring, multiple planet gears located between the gear ring and the sun gear, and a planet carrier. Figure 1 or Figure 2 The gear ring 20, planetary gear 21, planetary carrier 22, and sun gear 23 are shown in the diagram. The motor 30 is connected to the sun gear 23 through a two-stage gear. The motor 30, the first motor gear 31, and the second motor gear 32 constitute the motor assembly 3. The mid-mounted motor continuously variable transmission device also includes an output gear 4, which meshes with the planetary carrier 22 to receive the torque transmitted to the planetary carrier 22 by the motor assembly 3 and the central shaft 1 and to transmit the power to the wheel A.

[0046] The output shaft of the motor 30 has a gear, which is connected to the first gear 31 of the motor. The first gear 31 of the motor is a double gear. The other gear of the first gear 31 of the motor meshes with the second gear 32 of the motor. The second gear 32 of the motor is sleeved on the central shaft 1 and connected to the sun gear 23.

[0047] The planetary carrier 22 has a disk with a central hole. The outer edge of the disk is provided with bevel teeth. Multiple shafts connected to the planet gears 21 are arranged along the central axis on one end face of the disk. The central hole of the planetary carrier 22 is fitted around the connection between the sun gear 23 and the second gear 32 of the motor. The output gear 4 is a bevel gear that meshes with the bevel teeth on the outer edge of the disk.

[0048] Based on the working principle of planetary gear set 2, the rotational speed relationship between the central shaft 1, motor 30, and wheels of the central motor continuously variable transmission is determined by the following formula:

[0049] n MG / i1+k*n Z = (1+k)*i2*n W

[0050] Where: n MG i1 represents the rotational speed of motor 30; i1 represents the speed ratio between motor 30 and sun gear 23; k represents the speed ratio of planetary gear assembly 2; n Z i1 represents the rotational speed of the central shaft 1 (or gear ring 20); i2 represents the speed ratio between the planet carrier 22 and the wheel; n W This indicates the rotational speed of the wheel.

[0051] Specifically, the speed ratio between the motor 30 and the sun gear 23 is determined by i1 = n MG / n S This indicates that the speed ratio between the planetary carrier 22 and the wheel is determined by i2 = n. C / n W express.

[0052] Based on the above relationships, the following kinematic and dynamic relationships are further obtained:

[0053] n S +k*n Z = (1+k)*n C

[0054] T S :T Z :T C =1:k:(k+1)

[0055] Where: n S n Z n C These represent the rotational speeds of the sun gear 23, the central shaft 1 (or the ring gear 20), and the planet carrier 22, respectively; T S T Z T C These represent the torques of the sun gear 23, the central shaft 1 (or the gear ring 20), and the planet carrier 22, respectively; k represents the speed ratio of the planetary gear assembly 2.

[0056] Furthermore, based on the above relationships, the input power shunt principle of planetary gear set 2 is determined by the following formula:

[0057] P S +P Z =P C

[0058] In the formula: P S P Z P C These represent the power of motor 30 (or sun gear 23), central shaft 1 (or gear ring 20), and planet carrier 22 (or wheel), respectively.

[0059] By adjusting the assist ratio of the mid-mounted motor continuously variable transmission (CVT) to adapt to different operating conditions, and combining the above formula, the assist ratio of the mid-mounted motor CVT is determined by the following formula:

[0060]

[0061] In the formula: λ represents the assist ratio.

[0062] It should be noted that λ is related to the speed ratio of motor 30 and central shaft 1. By adjusting the speed of motor 30, the assist ratio λ can be adjusted to meet the needs of different working conditions.

[0063] In this embodiment, when the central shaft 1 rotates, it drives the gear ring 20 to rotate. When the motor 30 rotates in the opposite direction to the central shaft 1, the power transmitted to the sun gear 23 is sequentially input to the motor 30 through the second gear 32 and the first gear 31, causing the motor to generate electricity. When the motor 30 rotates in the same direction as the central shaft 1, the power of the motor 30 is sequentially transmitted to the sun gear 23 through the first gear 31 and the second gear 32. The sun gear 23 transmits the power to the planet carrier 22, so that the output power of the motor 30 and the output power of the central shaft 1 are combined and transmitted to the planet carrier 22. Finally, the power is transmitted to the output gear 4 by the planet carrier 22. By adjusting the speed of the motor 30, stepless speed change is achieved with the central shaft 1.

[0064] Example 4

[0065] Refer to the instruction manual appendix Figure 3-5 Based on Example 3, one or more functions can be achieved through the one-way clutch 6. Figure 3-5 In the diagram, S represents the sun gear 23, C represents the planet carrier 22, R represents the central shaft 1 or the gear ring 20, and n MG / i1 represents the rotational speed of sun gear 23, n W / i2 represents the rotational speed of planet carrier 22, n Z This indicates the rotational speed of the central shaft 1 or the gear ring 20.

[0066] The following description of different operating conditions further illustrates this embodiment:

[0067] Included in the instruction manual Figure 3 For example, in the case of the continuously variable transmission (CVT) with a mid-mounted motor, condition 1 is a low-speed, low-load condition. As the rider's pedal frequency increases (i.e., the speed of the bottom bracket 1 increases), the control system realizes the intention to accelerate and increases the speed of motor 30, so the bicycle is in an accelerated state. When the rider's pedal frequency stabilizes, the speed of motor 30 no longer increases, and the bicycle speed remains in the state of condition 2.

[0068] Included in the instruction manual Figure 4 For example, the continuously variable transmission (CVT) device with a mid-mounted motor is in a power generation state while driving. State 1 is a power-assisted driving state at a certain vehicle speed. When the load is low, the motor 30 enters the driving power generation state of State 2 according to the system requirements.

[0069] Included in the instruction manual Figure 5Taking the starting condition of the mid-mounted motor continuously variable transmission (CVT) as an example, at the moment of starting, the speed of the central shaft 1 is greater than that of the sun gear 23. The one-way clutch 6 is engaged, and the planetary gear set 2 is locked, with a speed ratio of 1. The central shaft 1, sun gear 23, and output wheel 4 all rotate at the same speed. Power is output to the output wheel 4 (or wheel A) via the planetary gear set 2. The starting process does not rely on the power assist system, so the starting response is fast, as shown in condition 1. When the motor 30 detects that the vehicle is starting, it immediately enters the power assist mode. The speed of the motor 30 increases, driving the sun gear 23 to rotate. Since the speed of the sun gear 23 is greater than that of the central shaft 1, the one-way clutch 6 disengages, and the planetary gear set 2 enters the input power split mode. The power from the motor 30 and the central shaft 1 is combined via the planetary carrier to the output wheel 4, driving wheel A to move.

[0070] The mid-mounted motor continuously variable transmission also features a pure human-powered riding mode. The one-way clutch 6 between the central shaft 1 and the sun gear 23 ensures that power can only be transmitted from the central shaft 1 to the sun gear 23 in one direction. When the rider is riding at low speed, the speed of the central shaft 1 is greater than that of the sun gear 23. The one-way clutch 6 engages, and the planetary gear assembly 2 locks, enabling pure human-powered low-speed riding.

[0071] The continuously variable transmission with a mid-mounted motor also has a limp-out function. When the motor system fails, it enters the limp-out mode. The pedal force drives the central shaft 1 to rotate, the one-way clutch 6 engages, the planetary gear set 2 is locked, and the power is output to the output wheel 4 (or wheel A) through the planetary gear set 2.

[0072] Using the structure of this embodiment, the mid-mounted motor continuously variable transmission device has at least a starting mode, an assist mode, a power generation mode, an input power split mode after starting, a pure human riding mode, and a limp mode, to meet the riding needs of different working conditions.

[0073] The above description is merely an embodiment of this utility model, and common knowledge regarding specific structures and characteristics is not described in detail here. It will be apparent to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this utility model is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A continuously variable transmission (CVT) device for a mid-mounted motor, comprising a planetary gear assembly, wherein the planetary gear assembly includes a ring gear, a sun gear located at the center of the ring gear, a plurality of planet gears located between the ring gear and the sun gear, and a planet carrier; characterized in that, It also includes a central shaft (1) and a motor; The central shaft (1) passes through the center of the sun gear and is fixedly connected to the gear ring. The output end of the motor is directly or indirectly connected to the sun gear. The central shaft (1) and the motor combine and output power to the wheel through the planetary gear assembly.

2. The continuously variable transmission device for a mid-mounted motor according to claim 1, characterized in that, It also includes a one-way clutch (6); one end of the one-way clutch (6) is connected to the central shaft (1), and the other end is connected to the sun gear of the planetary gear assembly.

3. The continuously variable transmission device for a mid-mounted motor according to claim 2, characterized in that, When the rotational speed of the central shaft (1) is greater than that of the sun gear, the one-way clutch (6) is engaged, the central shaft (1) and the sun gear rotate at the same speed, and the speed ratio is 1; when the rotational speed of the central shaft (1) is less than that of the sun gear, the one-way clutch (6) is disengaged, and the planetary gear assembly input power is split.

4. The continuously variable transmission device for a mid-mounted motor according to claim 1, characterized in that, The input power shunt principle of a planetary gear set is determined by the following formula: P S +P Z =P C In the formula: P S P Z P C These represent the power of the motor or sun gear, the central shaft or ring gear, and the planetary carrier, respectively.

5. The continuously variable transmission device for a mid-mounted motor according to claim 1, characterized in that, The assist ratio of the continuously variable transmission device for the centrally mounted motor is determined by the following formula: In the formula: λ represents the assist ratio; P S P Z These represent the power of the motor or sun gear and the central shaft or gear ring, respectively. T S T Z These represent the torques of the sun gear and the central shaft or ring gear, respectively; n S n Z These represent the rotational speeds of the sun gear and the central shaft or ring gear, respectively; n MG i1 represents the speed of the motor; k represents the speed ratio of the planetary gear set; i1 represents the speed ratio between the motor and the sun gear.

6. The continuously variable transmission device for a mid-mounted motor according to claim 1, characterized in that, The rotational speed relationship between the central shaft (1), the motor, and the wheels is determined by the following formula: n MG / i1+k*n Z =(1+k)*i2*n W Where: n MG i1 represents the speed of the motor; i1 represents the speed ratio between the motor and the sun gear; k represents the speed ratio of the planetary gear set; n Z i1 represents the rotational speed of the central axle; i2 represents the speed ratio between the planetary carrier and the wheels; n W This indicates the rotational speed of the wheel.

7. The continuously variable transmission device for a mid-mounted motor according to claim 2, characterized in that, The mid-mounted motor continuously variable transmission has at least the following operating modes: starting mode, assist mode, power generation mode, input power splitting mode after starting, pure human riding mode, and limp mode.

8. The continuously variable transmission device for a mid-mounted motor according to claim 2, characterized in that, The one-way clutch (6) adopts an overrunning clutch.

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