Motor mounting structure, in-line motor

Abstract

The application provides a motor mounting structure, comprising a motor support, a connecting rod and a motor body; the motor body is partially / fully fixed in the internal space of the motor support through the connecting rod; wherein three groups of through holes are arranged on the motor body and the motor support for penetrating the connecting rod, and the three groups of through holes are arranged at three positions: a first hole position, a second hole position and a third hole position; the central axis of the motor body and the gravity center of the motor are arranged in a triangle formed by the connecting line of the centers of the first hole position, the second hole position and the third hole position. The application can improve the stability of the motor when the central axis is stepped on by a person, make the connection between the motor and the frame more stable and avoid shaking; improve the rigidity of the motor bearing when the motor is driven, and improve the NVH (motor vibration noise) of the motor.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a motor mounting structure and a mid-mounted motor. Background Technology

[0002] In the field of electric-assist bicycles, a mid-drive motor refers to a motor whose drive motor is installed in the middle of the bicycle frame, near the pedals. This motor is connected to the frame and transmits power through a chain to the rear wheel. Pedals are installed on both sides of the motor. Current mid-drive motors can achieve pure electric mode, manual mode, and electric-assist mode, and have the advantages of being lightweight and convenient.

[0003] However, existing mid-drive motors are prone to problems such as unstable center of gravity and insufficient stability after the motor body is installed in the motor bracket. The motor body is also prone to misalignment, which leads to safety and reliability issues. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a motor mounting structure and a mid-mounted motor. According to the present invention, a motor mounting structure includes: a motor bracket, connecting rods, and a motor body;

[0005] The motor body is partially or completely fixed to the internal space of the motor bracket by the connecting rod;

[0006] The motor body and the motor bracket are provided with three sets of through holes for the connecting rod to pass through. The three sets of through holes are arranged in three positions: the first hole, the second hole and the third hole.

[0007] The central shaft of the motor body and the center of gravity of the motor are arranged within the triangle formed by the lines connecting the centers of the first hole, the second hole and the third hole.

[0008] Furthermore, the second hole is located directly above the central shaft of the motor body.

[0009] Furthermore, the line connecting the center of the second hole and the center shaft forms a longitudinal axis, the first transverse axis is perpendicular to the longitudinal axis and tangent to the upper part of the outer circle of the motor body, and the second transverse axis is perpendicular to the longitudinal axis and tangent to the lower part of the outer circle of the output gear of the motor body.

[0010] The vertical axis, the first horizontal axis, and the second horizontal axis divide the plane of the motor into six regions: the first region, the second region, the third region, the fourth region, the fifth region, and the sixth region.

[0011] Furthermore, the first hole is arranged in the first region;

[0012] The second hole is arranged in the third region and the sixth region and above the outer circle of the output gear;

[0013] The third hole is located in the fourth region.

[0014] Furthermore, the distance from the center of the first hole to the center of the central shaft is 150%-200% of the outer diameter of the output gear.

[0015] Furthermore, the distance from the center of the second hole to the center of the central shaft is 50%-80% of the outer diameter of the output gear of the motor body.

[0016] Furthermore, the distance from the center of the third hole to the center of the central shaft is 60%-90% of the outer diameter of the output gear of the motor body.

[0017] Furthermore, the angle between the line connecting the center of the first hole and the center of the central axis and the longitudinal axis is 30°-60°.

[0018] The angle between the center of the third hole and the center of the central axis is 140°-170°.

[0019] Furthermore, the distance between the motor core of the motor body and the center of the central shaft is 80%-120% of the outer diameter of the output gear of the motor body;

[0020] The outer diameter of the motor core is 80%-130% of the outer diameter of the output gear of the motor body;

[0021] The angle between the line connecting the center of the motor core and the center of the central shaft and the longitudinal axis is 50°-100°.

[0022] The center of the motor core is located in the sixth region.

[0023] A mid-drive motor according to the present invention includes the aforementioned motor mounting structure.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The invention features a rationally arranged layout of three mounting holes, with the central axis positioned within a triangle formed by the three holes. This improves motor stability when the central axis is manually operated, resulting in a more secure connection between the motor and the frame and preventing wobbling. The motor's center of gravity is also contained within this triangle, enhancing the rigidity of the motor bearings during operation and improving NVH (noise, vibration, and harshness). When the center of gravity is positioned within the supporting triangle, the line of action of gravity passes through this triangular area. According to the principle of statics (three points supporting a planar object), the gravity is evenly or proportionally distributed among the three support points. Each mounting point bears positive pressure (compressive load), a stress state that is most stable and advantageous for bolted connections and support structures. Positioning the center of gravity within this base means that regardless of the direction of external disturbances to the motor (such as vehicle acceleration, braking, turning, inertial forces or impacts caused by bumpy roads), the resulting overturning moment is more easily balanced by the supporting reaction moment formed by the three mounting points, improving motor stability and NVH. Attached Figure Description

[0026] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 This is a partial sectional view of the side of the present invention;

[0028] Figure 2 This is a front perspective view of the present invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0030] like Figure 1As shown, a motor mounting structure includes: a motor bracket 10, connecting rods, a first fixing member, an isolation layer 13, a motor body 14, and a second fixing member. The motor body 14 is partially / completely fixed to the internal space of the motor bracket 10 via the connecting rods. Multiple sets of through holes are provided on the motor body 14 and the motor bracket 10 for the connecting rods to pass through. The first fixing member and the second fixing member are respectively connected to the through holes on both sides of the motor body 14 in the motor bracket 10. The two ends of the connecting rods are indirectly connected to the motor bracket 10 via the first fixing member and the second fixing member, respectively. The isolation layer 13 covers the surface of the connecting rods to prevent direct contact between the connecting rods and the motor bracket 10 and the motor body 14. The first fixing member, the second fixing member, and the isolation layer 13 cut off the electrochemical corrosion-induced galvanic circuit, preventing electrochemical corrosion of the magnesium alloy due to potential differences, ensuring the corrosion resistance of the structure, extending the service life of the motor's magnesium alloy housing, and reducing maintenance and replacement costs caused by corrosion. In terms of installation, the accuracy of motor installation and positioning has been improved, ensuring the stability of motor operation; the size accuracy requirements of motor brackets have been reduced, simplifying the processing process, reducing processing costs, making assembly more efficient, and facilitating large-scale production applications.

[0031] In this embodiment, the connecting rod is further defined as a hanging screw 11, and the motor body 14 can be connected to the rod of the hanging screw 11. The first fixing member is a bushing 12, and the second fixing member is a nut 15. The tail of the hanging screw 11 is screwed onto the nut 15, and the head of the hanging screw 11 abuts against the bushing 12. The bushing 12 can be an aluminum alloy bushing. The isolation layer 13 is a non-metallic isolation material, a ceramic coating, or a zinc-nickel alloy coating / paint layer, etc.

[0032] For aesthetic reasons, the head and tail of the mounting screw 11 are preferably accommodated within the through hole. Therefore, the diameter of the through hole in the motor bracket 10 where the head of the mounting screw 11 is located is larger than the diameter of the head of the mounting screw 11, allowing the head of the mounting screw 11 to be accommodated within the through hole of the motor bracket 10. The bushing 12 abuts against the head of the mounting screw 11 and the motor body 14, and is partially interference-fitted into the through hole of the motor bracket 10 where the head of the mounting screw 11 is located. Thus, the head of the mounting screw 11 can be fixed to the corresponding position of the motor bracket 10 by fixing the bushing 12.

[0033] There is a preset gap between the motor body 14 and the motor bracket 10, with a gap of 0.1mm or more. This gap provides buffer space for motor installation, facilitating initial motor insertion. After the motor is installed in the motor bracket, the mounting screw 11 is tightened. The mounting screw 11 pushes the bushing 12 to move axially, and the bushing 12 fixes the motor to the motor bracket. Because the bushing 12 can move axially, it disperses the force of the mounting screw 11, preventing deformation of the motor bracket and making the motor installation positioning more accurate. At the same time, it reduces the dimensional accuracy requirements of the motor bracket installation, reduces the impact of machining errors, and improves assembly flexibility and convenience.

[0034] like Figure 2 As shown, the motor body 14 and the motor bracket 10 are provided with three sets of through holes for inserting the hanging screws 11. The three sets of through holes are arranged in three positions: the first hole position 1, the second hole position 2 and the third hole position 3.

[0035] A vertical axis is formed by connecting the centers of the second hole 2 and the central shaft 4. A first horizontal axis is perpendicular to the vertical axis and tangent to the top of the outer circle 5b of the motor body 14. A second horizontal axis is perpendicular to the vertical axis and tangent to the bottom of the outer circle 6b of the output gear of the motor body 14. The vertical axis, the first horizontal axis, and the second horizontal axis divide the plane of the motor into six regions: region 100, region 200, region 300, region 400, region 500, and region 600.

[0036] The central shaft 4 and the center of gravity 9 of the motor body 14 are arranged within the triangle formed by the line connecting the centers of the first hole 1, the second hole 2 and the third hole 3. The arrangement of the central shaft 4 can improve the stability of the motor when the central shaft is manually stepped on, making the connection between the motor and the frame more stable and avoiding shaking. The arrangement of the center of gravity of the motor can improve the rigidity of the motor bearing when the motor is driven, and improve the NVH of the motor.

[0037] The first hole 1 is arranged in the first region 100, the second hole 2 is arranged directly above the central shaft 4 of the motor body 14, the second hole 2 is arranged in the third region 300 and the sixth region 600 and above the outer circle 6b of the output gear, the third hole 3 is arranged in the fourth region 400, and the center 5a of the motor core 5 is arranged in the sixth region 600.

[0038] The distance 8c from the center 1a of the first hole 1 to the center 4a of the central shaft 4 is 150%-200% of the outer diameter 6b of the output gear, preferably 170%. This ensures that the mounting hole has sufficient lever arm to resist the gear meshing torque while avoiding housing deformation due to excessive lever arm length. This parameter design is based on the torque balance principle. According to the torque formula (T=FL), the lever arm length L directly affects the ability to resist gear meshing torque. When the lever arm is too short (e.g., <150%), the torque borne by the mounting hole will exceed the allowable stress of the material, leading to housing deformation; while when the lever arm is too long (e.g., >200%), the cantilever effect of the housing will be enhanced, causing local stress concentration. The value of 170% has been verified in experiments as the equilibrium point—it can convert torque into compressive stress with sufficient lever arm, avoiding shear stress on the bolt.

[0039] The distance 8a from the center 2a of the second hole 2 to the center 4a of the central shaft 4 is 50%-80% of the outer diameter 6b of the output gear of the motor body 14, preferably 60%. A shorter lever arm can reduce the vibration amplitude of the system and improve rigidity. This parameter is related to the vibration transmission path. A shorter lever arm can reduce the system's natural frequency and avoid resonance with the motor's operating frequency (such as the gear meshing frequency). According to vibration theory, shortening the lever arm reduces the vibration amplitude, thereby improving structural rigidity. Experiments show that when the lever arm is 60%, the system's first-order modal frequency can avoid the motor's main excitation frequency (such as 400Hz, 800Hz), reducing NVH problems.

[0040] The distance 8b from the center 3a of the third hole 3 to the center 4a of the central shaft 4 is 60%-90% of the outer diameter 6b of the output gear of the motor body 14, preferably 70%, to balance the load and ensure that the third hole and the first hole form an asymmetrical support, thus dispersing the radial force of the gear.

[0041] The angle 7d between the line connecting the center 1a of the first hole 1 and the center 4a of the central shaft 4 and the longitudinal axis is 30°-60°, with 50° being preferred to reduce the risk of screw slippage and improve screw anti-loosening capability. This angle achieves anti-loosening through the thread friction self-locking condition. According to the principle of tribology, when the thread helix angle is less than the friction angle, the thread pair can achieve self-locking. The experimental data in the table below shows that when the included angle is 50°, the matching between the thread helix angle and the friction angle reaches the optimal level. At this time, the anti-loosening torque can reach more than 75% of the preload torque, which is significantly better than the conditions of 30° or 60°.

[0042]

[0043] Data shows that the torque retention rate is highest at a 50° angle, verifying the anti-loosening advantage of this angle.

[0044] The angle 7e between the center 3a of the third hole 3 and the center 4a of the central shaft 4 is 140°-170°, preferably 150°, to counteract the unbalanced torque of the gear. This angle is used for torque balancing. The radial force generated during gear meshing creates an unbalanced torque. By arranging the third hole at 150°, the support reaction torque is made to be opposite in direction to the gear torque, thereby counteracting more than 90% of the overturning moment. According to the static equilibrium equation, this angle design can reduce the maximum bending moment of the shell by 40%.

[0045] The distance 9a between the motor core 5 of the motor body 14 and the center 4a of the central shaft 4 is 80%-120% of the outer diameter 6b of the output gear of the motor body 14, preferably 90%, in order to avoid the influence of motor heat radiation on gear lubrication while keeping the volume as small as possible.

[0046] The outer diameter 5b of the motor core 5 is 80%-130% of the outer diameter 6b of the output gear of the motor body 14, preferably 110%, in order to reduce the size of the motor as much as possible while ensuring gear strength and maximum output torque.

[0047] The angle 9b between the line connecting the center 5a of the motor core 5 and the center 4a of the central shaft 4 and the longitudinal axis is 50°-100°, preferably 70°, in order to minimize the size of the motor while avoiding the influence of the motor on the heat radiation of the gears.

[0048] When the center of gravity is positioned inside the supporting triangle, the line of action of gravity passes through this triangular region. According to the principle of statics (three points supporting a planar object), the gravity is evenly or proportionally distributed among the three support points. Each mounting point bears positive pressure (compressive load), and this stress state is the most stable and advantageous for bolted connections and support structures. Positioning the center of gravity inside this base means that regardless of the direction of external disturbances to the motor (such as vehicle acceleration, braking, turning, inertial forces or impacts caused by bumpy roads), the overturning moment generated is more easily balanced by the support reaction torque formed by the three mounting points, improving motor stability and NVH (noise, vibration, and harshness). When the center of gravity is projected within the triangle, the torque generated by gravity is evenly distributed among the three support points, with each mounting point bearing a compressive load (non-shear or tensile). Experiments show that this layout can reduce housing deformation by 60% while increasing bearing stiffness (e.g., reducing motor shaft deflection by 0.05 mm).

[0049] The motor mounting structure of the present invention can be applied to motors such as mid-drive motors.

[0050] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0051] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A motor mounting structure, characterized in that, include: Motor bracket (10), connecting rod and motor body (14); The motor body (14) is partially or completely fixed to the internal space of the motor bracket (10) by the connecting rod; The motor body (14) and the motor bracket (10) are provided with three sets of through holes for the connecting rod to pass through. The three sets of through holes are arranged in three positions: the first hole (1), the second hole (2) and the third hole (3). The central shaft (4) of the motor body (14) and the center of gravity (9) of the motor are arranged within the triangle formed by the line connecting the centers of the first hole (1), the second hole (2) and the third hole (3); The second hole (2) is located directly above the central shaft (4) of the motor body (14); The line connecting the center of the second hole (2) and the center shaft (4) forms the longitudinal axis. The first horizontal axis is perpendicular to the longitudinal axis and tangent to the upper part of the outer circle (5b) of the motor body (14). The second horizontal axis is perpendicular to the longitudinal axis and tangent to the lower part of the outer circle (6b) of the output gear of the motor body (14). The vertical axis, the first horizontal axis, and the second horizontal axis divide the plane of the motor into six regions: the first region (100), the second region (200), the third region (300), the fourth region (400), the fifth region (500), and the sixth region (600). The first hole (1) is arranged in the first region (100); The second hole (2) is arranged in the third region (300) and the sixth region (600) and above the outer circle (6b) of the output gear; The third hole (3) is located in the fourth region (400).

2. The motor mounting structure according to claim 1, characterized in that, The distance (8c) from the center (1a) of the first hole (1) to the center (4a) of the central shaft (4) is 150%-200% of the diameter of the outer circle (6b) of the output gear.

3. The motor mounting structure according to claim 1, characterized in that, The distance (8a) from the center (2a) of the second hole (2) to the center (4a) of the central shaft (4) is 50%-80% of the outer diameter (6b) of the output gear of the motor body (14).

4. The motor mounting structure according to claim 1, characterized in that, The distance (8b) from the center (3a) of the third hole (3) to the center (4a) of the central shaft (4) is 60%-90% of the outer diameter (6b) of the output gear of the motor body (14).

5. The motor mounting structure according to claim 1, characterized in that, The angle (7d) between the line connecting the center (1a) of the first hole (1) and the center (4a) of the central axis (4) and the longitudinal axis is 30°-60°. The angle (7e) between the line connecting the center (3a) of the third hole (3) and the center (4a) of the central axis (4) and the longitudinal axis is 140°-170°.

6. The motor mounting structure according to claim 1, characterized in that, The distance (9a) between the center (5a) of the motor core (5) of the motor body (14) and the center (4a) of the central shaft (4) is 80%-120% of the outer diameter (6b) of the output gear of the motor body (14); The outer diameter (5b) of the motor core (5) is 80%-130% of the outer diameter (6b) of the output gear of the motor body (14); The angle (9b) between the line connecting the center (5a) of the motor core (5) and the center (4a) of the central shaft (4) and the longitudinal axis is 50°-100°. The center (5a) of the motor core (5) is located in the sixth region (600).

7. A mid-drive motor, characterized in that, Includes the motor mounting structure as described in any one of claims 1-6.

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