Electric power-assisted steering structure for motorcycle

Abstract

The application relates to the field of motorcycle steering, and discloses an electric power-assisted steering structure for a motorcycle, which comprises a shell and an upper cover, the shell and the upper cover are connected to form a mounting cavity, a steering shaft assembly is rotatably arranged in the mounting cavity, a sensor assembly is arranged in the mounting cavity and sleeved outside the steering shaft assembly to detect the rotating state, a main transmission gear is coaxially arranged outside the steering shaft assembly, a power-assisted motor is arranged on one side of the shell, an output shaft of the power-assisted motor is parallel to the steering shaft assembly, a motor shaft gear is arranged on the output shaft of the power-assisted motor, a gear reduction assembly is arranged in the mounting cavity, the main transmission gear, the gear reduction assembly and the motor shaft gear are sequentially meshed, the power-assisted motor output power-assisted torque is increased in torque and then transmitted to an output end of the steering shaft assembly, and a through hole is formed in the shell and used for allowing a wire harness of the sensor assembly to pass through. The application is used to solve the problems of heavy operation of the motorcycle steering structure at low speed and insufficient stability at high speed.

Description

Technical Field

[0001] This invention relates to the field of motorcycle steering technology, and in particular to an electric power steering structure for motorcycles. Background Technology

[0002] As a flexible and convenient means of transportation, the handling performance of the steering system of a motorcycle is directly related to the safety and comfort of riding. Traditional motorcycle steering systems mostly use mechanical structures, in which the rider directly drives the front wheel to steer through components such as the handlebars. This type of steering structure is low in cost and simple to maintain. However, as motorcycles develop towards larger displacement, higher speed, and heavier weight, the shortcomings of traditional mechanical steering systems have gradually become apparent. When making U-turns at low speeds, maneuvering on the spot, or turning in narrow spaces, the rider needs to directly overcome the frictional resistance between the tires and the ground, as well as the resistance of the steering mechanism, resulting in relatively heavy steering operation and easy fatigue. When riding at high speeds or over bumpy roads, the handlebars are prone to shaking or failing to return to center stably, affecting the stability of vehicle handling and riding safety.

[0003] Electric power steering systems are widely used in the automotive industry. These systems use sensors to detect steering input and a motor to provide auxiliary torque, reducing steering load. However, automotive electric power steering systems are typically large and complex, especially those using worm gear transmission mechanisms. These systems are bulky, heavy, and expensive, making them unsuitable for motorcycles. Motorcycles have a compact front structure, and the steering components are directly exposed, making them more susceptible to mud, water, and dust. Therefore, there is a need for an electric power steering structure suitable for the limited installation space of motorcycles, which can provide steering assistance while maintaining a compact structure, and also consider transmission efficiency and assembly reliability. Summary of the Invention

[0004] The purpose of this invention is to provide an electric power steering structure for motorcycles, which solves the problems of existing motorcycle steering structures being heavy to operate at low speeds and lacking stability at high speeds.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an electric power steering structure for motorcycles, including a housing and a top cover, the housing and the top cover being connected to form a mounting cavity, and a steering shaft assembly, the steering shaft assembly being rotatably inserted through the mounting cavity, a sensor assembly being disposed within the mounting cavity, the sensor assembly being sleeved outside the steering shaft assembly to detect the rotation state, a main drive gear being coaxially disposed outside the steering shaft assembly, a power assist motor being disposed on one side of the housing, the output shaft of the power assist motor being parallel to the steering shaft assembly, a motor shaft gear being disposed on the output shaft of the power assist motor, a gear reduction assembly being disposed within the mounting cavity, the main drive gear, the gear reduction assembly and the motor shaft gear being meshed in sequence, the power assist torque output by the power assist motor being amplified and then transmitted to the output end of the steering shaft assembly, and a through hole being provided on the housing for the wiring harness of the sensor assembly to pass through.

[0006] A further configuration of the present invention is as follows: the steering shaft assembly includes an input shaft, a torsion bar, and a lower steering spindle arranged coaxially. The input shaft is fixedly connected to the torsion bar by a cylindrical pin. A sliding bearing is sleeved on the lower end of the torsion bar. The outer side of the sliding bearing is in contact with the inner wall of the lower steering spindle, so that a relative torsional deformation for torque detection can be generated between the input shaft and the lower steering spindle. The main drive gear is coaxially fixed outside the lower steering spindle, and the main drive gear meshes with the gear reduction assembly.

[0007] A further configuration of the present invention is as follows: the sensor assembly includes a sensor body fixed inside the housing, a sensor rotor coaxially rotatably disposed below the sensor body, the sensor rotor being sleeved outside the lower steering spindle, used to detect the relative steering angle between the input shaft and the lower steering spindle, as well as the steering torque of the torsion bar torsional deformation.

[0008] A further configuration of the present invention is as follows: the steering shaft assembly includes an output shaft, which is rotatably connected to the housing through the mounting cavity. The upper end of the output shaft is connected to the motorcycle handlebars, and the lower end of the output shaft is connected to the motorcycle steering column. The main drive gear is coaxially fixed outside the output shaft, and the sensor assembly is fixed inside the housing for detecting the rotation angle and rotation speed of the steering shaft assembly.

[0009] A further configuration of the present invention is as follows: the gear reduction assembly includes a first gear and a second gear that are coaxially fixed to each other. The first gear and the second gear are coaxially fixed on the reduction shaft. The diameter of the first gear is smaller than that of the second gear. The first gear meshes with the main drive gear, and the second gear meshes with the motor shaft gear.

[0010] A further feature of the present invention is that the teeth of the first gear and the second gear are made of nylon.

[0011] A further configuration of the present invention is as follows: the bottom of the housing has a first shaft hole for the steering shaft assembly to pass through and a second shaft hole for mounting the gear reduction assembly. A four-point contact ball bearing is installed in the first shaft hole, and a first deep groove ball bearing is installed in the second shaft hole. The upper cover has a corresponding third shaft hole and a fourth shaft hole. A second deep groove ball bearing is installed in the third shaft hole, and a third deep groove ball bearing is installed in the fourth shaft hole. The inner rings of the four-point contact ball bearing and the second deep groove ball bearing are connected to both ends of the steering shaft assembly, and the inner rings of the first deep groove ball bearing and the third deep groove ball bearing are connected to both ends of the reduction shaft. After the housing and the upper cover are closed, the steering shaft assembly and the gear reduction assembly are restricted to rotating around their respective axes.

[0012] A further feature of the present invention is that a sealing kit is provided at the connection between the housing and the top cover, at the connection between the power motor and the housing, and on the side of the four-point contact ball bearing, the first deep groove ball bearing, the second deep groove ball bearing, and the third deep groove ball bearing facing outward from the mounting cavity. The sealing kit is a rubber sealing ring.

[0013] The beneficial effects of this invention are:

[0014] 1. The rotational state of the steering shaft assembly is detected by the sensor assembly, and the power assist motor, gear reduction assembly and main drive gear are used to output power assist torque to the steering shaft assembly, so that the steering force required by the driver when turning at low speed and making U-turns is reduced; at the same time, when driving at high speed or when affected by road disturbances, the power assist motor can form auxiliary damping or stabilization assistance, thereby improving handling comfort and driving stability.

[0015] 2. By integrating the steering shaft assembly, sensor assembly, and gear reduction assembly into the mounting cavity formed by the housing and the top cover, and arranging the power assist motor on one side of the housing, the output shaft of the power assist motor is parallel to the steering shaft assembly. A two-stage gear reduction transmission is formed through the motor shaft gear, the gear reduction assembly, and the main drive gear. This structure is compact and has high transmission efficiency, while being easy to assemble, making it suitable for use in the limited installation space of motorcycles.

[0016] 3. The steering shaft assembly and gear reduction assembly are supported by multiple bearings respectively. After the housing is closed with the top cover, the steering shaft assembly and gear reduction assembly are restricted to rotating around their respective axes. This helps to improve the stability of gear meshing, reduce yaw and lateral movement, and improve steering feel. At the same time, sealing kits are set at each connection to reduce the entry of impurities such as mud, water and dust into the mounting cavity. This is suitable for the installation environment of motorcycles exposed to the elements and improves the reliability of bearings, gears and sensor assemblies. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of an electric power steering structure for motorcycles according to the present invention;

[0019] Figure 2 This is a cross-sectional view of an electric power steering structure for motorcycles according to Embodiment 1 of the present invention;

[0020] Figure 3 This is a cross-sectional view of an electric power steering structure for motorcycles according to Embodiment 1 of the present invention;

[0021] Figure 4 This is a schematic diagram of a motorcycle electric power steering structure with the housing and top cover removed, according to Embodiment 2 of the present invention.

[0022] In the diagram, 11. Housing; 12. Top cover; 2. Steering shaft assembly; 21. Input shaft; 22. Torsion bar; 221. Sliding bearing; 23. Lower steering spindle; 24. Main drive gear; 25. Output shaft; 3. Sensor assembly; 31. Sensor body; 32. Sensor rotor; 4. Power assist motor; 41. Motor shaft gear; 5. Gear reduction assembly; 51. First gear; 52. Second gear; 53. Reduction shaft; 61. Four-point contact ball bearing; 62. First deep groove ball bearing; 63. Second deep groove ball bearing; 64. Third deep groove ball bearing; 65. Sealing kit. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] As shown in the figure, the present invention provides an electric power steering structure for motorcycles, including a housing 11, a top cover 12, a steering shaft assembly 2, a sensor assembly 3, a power steering motor 4, and a gear reduction assembly 5.

[0025] The housing 11 is the main load-bearing component of this structure, used to install the steering shaft assembly 2, sensor assembly 3, gear reduction assembly 5, and power assist motor 4. The upper cover 12 covers the housing 11 and is connected to the housing 11 to form a mounting cavity. The mounting cavity is used to accommodate components such as the sensor assembly 3, main drive gear 24, and gear reduction assembly 5, so that each transmission component is in a relatively closed working space, which is beneficial to improving the integration of the assembly and the protection performance against external impurities.

[0026] The steering shaft assembly 2 is rotatably mounted in the mounting cavity. The steering shaft assembly 2 is used to transmit the steering action input by the driver and serves as an output component for superimposed assist torque. The upper end of the steering shaft assembly 2 can be connected to the motorcycle handlebars, and the lower end can be connected to the motorcycle steering column or the vehicle steering mechanism. A main drive gear 24 is coaxially arranged on the outside of the steering shaft assembly 2. The main drive gear 24 is used to receive the assist torque from the gear reduction assembly 5 and transmit the assist torque to the steering shaft assembly 2.

[0027] The sensor assembly 3 is installed inside the mounting cavity and sleeved on the outside of the steering shaft assembly 2. The sensor assembly 3 is used to detect the rotation state of the steering shaft assembly 2. The rotation state includes the rotation angle and rotation speed, and may also include torque-related signals generated by the torsional deformation of the torsion bar 22. A through hole is provided on the housing 11, and the wiring harness of the sensor assembly 3 extends out of the housing 11 through the through hole so as to be electrically connected to an external controller. The through hole is preferably located in a position where the wiring harness lead-out path is short and avoids the gear meshing area, so as to reduce the difficulty of wiring harness arrangement.

[0028] The power assist motor 4 is located on one side of the housing 11. The output shaft of the power assist motor 4 is arranged parallel to the steering shaft assembly 2. With this arrangement, the power assist motor 4 does not need to be stacked along the axial direction of the steering shaft assembly 2, which helps to reduce the axial height of the whole machine and makes it easier to arrange this structure in the limited space at the front of the motorcycle. The output shaft of the power assist motor 4 is provided with a motor shaft gear 41, which is used to output the rotational torque of the power assist motor 4 to the gear reduction assembly 5.

[0029] The gear reduction assembly 5 is installed in the mounting cavity, located between the motor shaft gear 41 and the main drive gear 24. The gear reduction assembly 5 includes a first gear 51, a second gear 52, and a reduction shaft 53. The first gear 51 and the second gear 52 are coaxially fixed on the reduction shaft 53. The diameter of the first gear 51 is smaller than that of the second gear 52. The first gear 51 meshes with the main drive gear 24, and the second gear 52 meshes with the motor shaft gear 41. During operation, the power assist motor 4 drives the motor shaft gear 41 to rotate, which in turn drives the second gear 52 and the reduction shaft 53 to rotate. The reduction shaft 53 drives the first gear 51 to rotate synchronously, and the first gear 51 then drives the main drive gear 24 to rotate, thereby transmitting the power assist torque to the steering shaft assembly 2.

[0030] Since the diameter of the second gear 52 is larger than that of the motor shaft gear 41, and the diameter of the main drive gear 24 is larger than that of the first gear 51, the above transmission path can form a two-stage reduction and torque increase. Compared with worm gear transmission, the spur gear meshing structure is mature in processing and has higher transmission efficiency, and the meshing response is more direct. It is suitable for motorcycle steering assist structures with high requirements for size and response. The teeth of the first gear 51 and the second gear 52 are preferably made of nylon. Nylon teeth have the advantages of light weight, low meshing noise, and certain self-lubricating properties, which are beneficial to reducing gear meshing noise and overall weight. The reduction shaft 53 can be made of metal to ensure the support strength and transmission rigidity of the gear reduction assembly 5.

[0031] The bottom of the housing 11 has a first shaft hole for the steering shaft assembly 2 to pass through and a second shaft hole for installing the gear reduction assembly 5. A four-point contact ball bearing 61 is installed in the first shaft hole, and a first deep groove ball bearing 62 is installed in the second shaft hole. The upper cover 12 has a third shaft hole corresponding to the first shaft hole and a fourth shaft hole corresponding to the second shaft hole. A second deep groove ball bearing 63 is installed in the third shaft hole, and a third deep groove ball bearing 64 is installed in the fourth shaft hole.

[0032] The inner rings of the four-point contact ball bearing 61 and the second deep groove ball bearing 63 are connected to both ends of the steering shaft assembly 2, and the outer rings are respectively fitted with the first shaft hole and the third shaft hole, thereby providing support for the upper and lower ends of the steering shaft assembly 2. The four-point contact ball bearing 61 can simultaneously bear radial load and a certain bidirectional axial load, and has good axial limiting capability. It is suitable for being arranged near the bottom of the housing 11 of the steering shaft assembly 2 to bear the axial force and yaw moment during the steering process. The second deep groove ball bearing 63 has a simple structure and low frictional resistance, and is suitable as the other end support of the steering shaft assembly 2 to ensure smooth rotation of the steering shaft assembly 2.

[0033] The inner rings of the first deep groove ball bearing 62 and the third deep groove ball bearing 64 are connected to both ends of the reduction shaft 53, and the outer rings are respectively fitted to the second shaft hole and the fourth shaft hole, thus forming a two-end support for the reduction shaft 53. The reduction shaft 53 mainly bears the radial load generated by gear meshing. Deep groove ball bearings have the characteristics of low friction and low cost, making them suitable as support bearings for the reduction shaft 53. After the housing 11 is closed with the upper cover 12, the steering shaft assembly 2 and the gear reduction assembly 5 are respectively restricted to rotate around their respective axes, thereby ensuring the stable meshing position of the main drive gear 24, the first gear 51, the second gear 52 and the motor shaft gear 41, and reducing meshing deviation.

[0034] A sealing kit 65 is provided at the connection between the housing 11 and the top cover 12, and a sealing kit 65 is also provided at the connection between the power motor 4 and the housing 11. In addition, a sealing kit 65 is provided on the side of the four-point contact ball bearing 61, the first deep groove ball bearing 62, the second deep groove ball bearing 63, and the third deep groove ball bearing 64 facing outward from the mounting cavity. The sealing kit 65 is a rubber sealing ring. The rubber sealing ring has good elasticity and strong compensation ability for compression deformation. It can form protection for the housing 11, the top cover 12, the power motor 4, and the outside of the bearings, reducing the entry of impurities such as mud, water, and dust into the mounting cavity and extending the service life of each bearing, gear, and sensor assembly 3.

[0035] Example 1: Torque plus Angle Detection Structure

[0036] like Figures 2-3 As shown, in this embodiment, the steering shaft assembly 2 includes an input shaft 21, a torsion bar 22, and a lower steering spindle 23 arranged coaxially. The input shaft 21 is used to connect to the motorcycle handlebars to receive the steering force applied by the rider. The input shaft 21 is fixedly connected to the torsion bar 22 by a cylindrical pin, so that the rotation of the input shaft 21 can be transmitted to the torsion bar 22. The cylindrical pin connection structure has good positioning and shear resistance, and is suitable for the fixed connection between the input shaft 21 and the torsion bar 22.

[0037] A torsion bar 22 is disposed between the input shaft 21 and the lower steering spindle 23 to generate detectable torsional deformation when the driver applies steering force. A sliding bearing 221 is sleeved on the lower end of the torsion bar 22. The outer side of the sliding bearing 221 is in contact with the inner wall of the lower steering spindle 23. The sliding bearing 221 is used to form a rotational support and radial limit between the torsion bar 22 and the lower steering spindle 23, so that the two can remain coaxial, while allowing relative torsion between the input shaft 21 and the lower steering spindle 23 for torque detection.

[0038] The lower steering spindle 23 is used to output steering force and assist torque to the motorcycle steering column. The main drive gear 24 is coaxially fixed outside the lower steering spindle 23 and meshes with the gear reduction assembly 5. The assist torque output by the assist motor 4 is transmitted to the lower steering spindle 23 through the motor shaft gear 41, the second gear 52, the reduction shaft 53, the first gear 51 and the main drive gear 24, thereby assisting the driver's steering operation.

[0039] The sensor assembly 3 includes a sensor body 31 fixed inside the housing 11. A sensor rotor 32 is coaxially rotatably disposed below the sensor body 31. The sensor rotor 32 is sleeved outside the lower steering spindle 23 and is used to cooperate with the sensor body 31 to detect the relative steering angle between the input shaft 21 and the lower steering spindle 23, as well as the steering torque formed by the torsional deformation of the torsion bar 22. Through this structure, the controller can detect the driver's steering intention based on the deformation of the torsion bar 22 and control the power assist motor 4 to output the corresponding power assist torque based on the steering torque and steering angle.

[0040] This embodiment is applicable to motorcycle models that require high precision in power assist control and steering feel. Because it can detect torque and angle information, it is beneficial to achieve more precise power assist adjustment.

[0041] Example 2: Angle-only detection structure

[0042] like Figure 4 As shown, in this embodiment, the steering shaft assembly 2 includes an output shaft 25, which passes through the mounting cavity and is rotatably connected to the housing 11. The upper end of the output shaft 25 is connected to the motorcycle handlebars, and the lower end is connected to the motorcycle steering column. The main drive gear 24 is coaxially fixed outside the output shaft 25 and meshes with the gear reduction assembly 5.

[0043] The sensor assembly 3 is fixed inside the housing 11 and is used to detect the rotation angle and rotation speed of the steering shaft assembly 2. The controller can determine the driver's steering operation status based on the rotation angle and rotation speed and control the power assist motor 4 to output corresponding power assist. Compared with the first embodiment, this embodiment eliminates torque detection-related components such as the torsion bar 22, the lower steering spindle 23 and the sliding bearing 221, resulting in a simpler structure, fewer parts, and lower cost, making it suitable for models with high requirements for cost and structural simplification.

[0044] Although this embodiment does not directly detect torque, the steering state can still be obtained through the rotation angle and rotation speed of the output shaft 25, and the power assist torque is applied to the output shaft 25 through the power assist motor 4 and the gear reduction assembly 5, thereby realizing the basic electric power steering function.

[0045] The above description shows and illustrates the basic principles, main features, and advantages of the present invention. Standard parts used in the present invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts, and equipment adopt conventional models in the prior art, which will not be described in detail here.

[0046] The control method of this invention is to control the device by manually starting and stopping the switch. The wiring diagram of the power element and the supply of power are common knowledge in the field. Since this invention is mainly used to protect mechanical devices, the control method and wiring layout will not be explained in detail.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electric power steering structure for motorcycles, comprising a housing (11) and a top cover (12), wherein the housing (11) and the top cover (12) are connected to form a mounting cavity, characterized in that: It also includes a steering shaft assembly (2), which is rotatably inserted through the mounting cavity. A sensor assembly (3) is provided in the mounting cavity. The sensor assembly (3) is sleeved on the outside of the steering shaft assembly (2) to detect the rotation state. A main drive gear (24) is coaxially arranged outside the steering shaft assembly (2). An assist motor (4) is provided on one side of the housing (11). The output shaft of the assist motor (4) is parallel to the steering shaft assembly (2). A motor shaft gear (41) is provided on the output shaft of the assist motor (4). A gear reduction assembly (5) is provided in the mounting cavity. The main drive gear (24), the gear reduction assembly (5) and the motor shaft gear (41) mesh in sequence to increase the assist torque output by the assist motor (4) and transmit it to the output end of the steering shaft assembly (2). A through hole is provided on the housing (11) for the wire harness of the sensor assembly (3) to pass through.

2. The electric power steering structure for motorcycles according to claim 1, characterized in that: The steering shaft assembly (2) includes an input shaft (21), a torsion bar (22), and a lower steering spindle (23) arranged coaxially. The input shaft (21) is fixedly connected to the torsion bar (22) by a cylindrical pin. A sliding bearing (221) is sleeved on the lower end of the torsion bar (22). The outer side of the sliding bearing (221) is in contact with the inner wall of the lower steering spindle (23), so that the input shaft (21) and the lower steering spindle (23) can generate relative torsional deformation for torque detection. The main drive gear (24) is coaxially fixed outside the lower steering spindle (23), and the main drive gear (24) meshes with the gear reduction assembly (5).

3. The electric power steering structure for motorcycles according to claim 2, characterized in that: The sensor assembly (3) includes a sensor body (31) fixed inside the housing (11), and a sensor rotor (32) is coaxially rotatably disposed below the sensor body (31). The sensor rotor (32) is sleeved outside the lower steering spindle (23) and is used to detect the relative steering angle between the input shaft (21) and the lower steering spindle (23), as well as the steering torque of the torsion bar (22) due to torsional deformation.

4. The electric power steering structure for motorcycles according to claim 1, characterized in that: The steering shaft assembly (2) includes an output shaft (25), which is rotatably connected to the housing (11) through the mounting cavity. The upper end of the output shaft (25) is connected to the motorcycle handlebars, and the lower end of the output shaft (25) is connected to the motorcycle steering column. The main drive gear (24) is coaxially fixed outside the output shaft (25). The sensor assembly (3) is fixed inside the housing (11) and is used to detect the rotation angle and rotation speed of the steering shaft assembly.

5. The electric power steering structure for motorcycles according to claim 1, characterized in that: The gear reduction assembly (5) includes a first gear (51) and a second gear (52) that are coaxially fixed to each other. The first gear (51) and the second gear (52) are coaxially fixed on the reduction shaft (53). The diameter of the first gear (51) is smaller than that of the second gear (52). The first gear (51) meshes with the main drive gear (24), and the second gear (52) meshes with the motor shaft gear (41).

6. The electric power steering structure for motorcycles according to claim 5, characterized in that: The teeth of the first gear (51) and the second gear (52) are made of nylon.

7. The electric power steering structure for motorcycles according to claim 5, characterized in that: The bottom of the housing (11) has a first shaft hole for the steering shaft assembly (2) to pass through and a second shaft hole for the gear reduction assembly (5) to be installed. A four-point contact ball bearing (61) is installed in the first shaft hole, and a first deep groove ball bearing (62) is installed in the second shaft hole. The upper cover (12) has a third shaft hole and a fourth shaft hole respectively. A second deep groove ball bearing (63) is installed in the third shaft hole, and a third deep groove ball bearing (64) is installed in the fourth shaft hole. The inner rings of the four-point contact ball bearing (61) and the second deep groove ball bearing (63) are connected to both ends of the steering shaft assembly (2). The inner rings of the first deep groove ball bearing (62) and the third deep groove ball bearing (64) are connected to both ends of the reduction shaft (53). After the housing (11) and the upper cover (12) are closed, the steering shaft assembly (2) and the gear reduction assembly (5) are restricted to rotating around their respective axes.

8. The electric power steering structure for motorcycles according to claim 7, characterized in that: At the connection between the housing (11) and the top cover (12), at the connection between the power motor (4) and the housing (11), and on the side of the four-point contact ball bearing (61), the first deep groove ball bearing (62), the second deep groove ball bearing (63), and the third deep groove ball bearing (64) facing the outside of the mounting cavity, a sealing kit (65) is provided. The sealing kit (65) is a rubber sealing ring.

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