Few-tooth differential wheel-side motor

Abstract

The utility model discloses a few tooth difference wheel edge motor, including transmission's motor unit, primary reduction mechanism and secondary reduction mechanism in proper order, and secondary reduction mechanism is docked and drives vehicle wheel hub rotation, the drive shaft of motor unit is docked the input shaft of primary reduction mechanism, and primary reduction mechanism is the planetary structure of involute few tooth difference and has the hole pin type output mechanism, and the secondary input gear is fixedly arranged on the primary output disc of primary reduction mechanism, and the secondary input gear is engaged with the secondary output gear of secondary reduction mechanism, and the output shaft is arranged on the secondary output gear and is docked vehicle wheel hub, the utility model discloses a design through the primary few tooth difference planetary transmission combination cylindrical gear drive, compares with the current two stage NGW system, and the transmission ratio distribution is optimized, and total transmission ratio is bigger, and the structure is simplified obviously, and cost is reduced, and the size is more compact in axial direction, and torsional stiffness is higher, and the reliability is improved obviously.

Description

Technical Field

[0001] This utility model relates to the field of new energy vehicle drive technology, and more specifically, it relates to a wheel-side motor with a small tooth difference. Background Technology

[0002] Wheel-side motors are a core technology for distributed new energy vehicle drives and an important direction for development. The principle of wheel-side motors is to install the drive motor directly next to the wheel, transmitting power to the wheel through a reduction mechanism. This eliminates traditional components such as clutches, gearboxes, drive shafts, and differentials, simplifying the overall vehicle structure, improving transmission efficiency, and enabling flexible chassis control, such as torque vectoring.

[0003] Currently, NGW (internal meshing-common gear-external meshing) planetary gear reducers are widely used in wheel-side motors due to their compact structure and high load-bearing capacity. However, they have the following drawbacks: 1. Complex structure and numerous parts. NGW wheel-side gear trains must include a sun gear, 3-4 planet gears, an internal gear ring, a planet carrier, and a complex load-sharing mechanism. The overall number of parts is large, requiring high precision in machining and assembly, resulting in high manufacturing costs; 2. Large axial dimension. Multiple planet gears need to be evenly distributed in the circumferential direction, and sufficient axial space is required to arrange the planet carrier and bearings, making it difficult to shorten the axial length of the reducer and difficult to arrange in the narrow space of the wheel-side; 3. Limited single-stage transmission ratio. Due to structural and meshing requirements, the transmission ratio of a single-stage NGW is usually less than ten. To obtain the large reduction ratio required by wheel-side motors, two or even three stages of NGW transmissions are often used in series, further increasing the complexity of the structure and the size and weight of the transmission parts; 4. High requirements for planet carrier dynamic balance. High-speed rotating planet carriers require precise dynamic balancing, otherwise, significant vibration and noise will occur. Therefore, there is an urgent need for a motor transmission structure that is more streamlined, has a better transmission ratio, and is more axially compact, suitable for wheel-side drive. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a wheel-side motor with a small tooth difference to solve one or more of the above-mentioned problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The low-tooth-difference wheel-side motor includes a motor unit, a first-stage reduction mechanism, and a second-stage reduction mechanism that are driven in sequence. The second-stage reduction mechanism is connected to and drives the vehicle wheel hub to rotate.

[0007] The drive shaft of the motor unit is connected to the input shaft of the first-stage reduction mechanism. The first-stage reduction mechanism is an involute planetary structure with a small tooth difference and a pin-type output mechanism. A second-stage input gear is fixedly mounted on the first-stage output disk of the first-stage reduction mechanism. The second-stage input gear meshes with the second-stage output gear of the second-stage reduction mechanism. An output shaft passes through the second-stage output gear and is connected to the vehicle wheel hub.

[0008] Furthermore, the motor unit also includes a motor stator and a motor rotor. The motor stator is fixed inside the housing of the low-tooth differential wheel motor, and the drive shaft passes through the motor rotor. The motor stator is energized and drives the motor rotor and the drive shaft to rotate synchronously.

[0009] Furthermore, the input shaft is provided with an eccentric portion;

[0010] The primary reduction mechanism also includes an external gear, an internal gear ring, and a pin shaft with a pin sleeve.

[0011] The eccentric part on the input shaft is connected to the external gear through a bearing sleeve. The external gear and the internal gear ring mesh internally and there is a difference in the number of teeth.

[0012] The external gear has circumferentially distributed and through output holes, and the first-stage output disk has corresponding holes. The first-stage output disk is connected to the external gear through the pin shaft to form a pin-type output mechanism.

[0013] Furthermore, the internal gear ring is fixed inside the housing of the low-tooth-difference wheel-side motor or fixed on the vehicle wheel hub bracket;

[0014] The difference in the number of teeth between the external gear and the internal gear ring is 1 to 4 teeth.

[0015] Furthermore, the input shaft drives the external gear, the first-stage output disk, and the second-stage input gear to synchronously perform involute planetary transmission with small tooth difference along the internal gear ring via the eccentric part.

[0016] Furthermore, the transmission ratio i1 of the first-stage reduction mechanism is 30 to 100.

[0017] Furthermore, the secondary input gear is coaxially and fixedly connected to the primary output disk;

[0018] The secondary output gear meshes externally with the secondary input gear.

[0019] Furthermore, the secondary input gear drives the secondary output gear and the output shaft to rotate synchronously, and the output shaft outputs the vehicle wheel hub.

[0020] Furthermore, the diameter of the secondary output gear is larger than that of the secondary input gear;

[0021] The transmission ratio i2 of the secondary reduction mechanism is 3 to 5.

[0022] In summary, this utility model has the following beneficial effects: Compared with the existing two-stage NGW planetary gear transmission structure, by combining a first-stage planetary transmission with a small tooth difference with a second-stage cylindrical gear transmission, a large speed ratio of 30-100 is achieved in the first stage and a moderate speed ratio of 3-5 in the second stage, with a total transmission ratio reaching hundreds. The overall transmission ratio distribution is more optimized and less restrictive. It eliminates the need for two complete NGW planetary gear systems, significantly reducing the types and number of parts, greatly simplifying the assembly process, and lowering manufacturing and maintenance costs. The axial dimension of the small tooth difference transmission structure is extremely short. Although a cylindrical gear transmission is added, the overall axial length of the structure is more excellent due to the reasonable layout of the cylindrical gear pairs in the radial space. The first-stage small tooth difference transmission has a large number of meshing teeth and good rigidity, while the second-stage external meshing cylindrical gear transmission chain is short and direct, resulting in higher torsional stiffness of the entire structure, which is beneficial for improving the dynamic response accuracy of control. The use of a pin-type transmission mechanism provides strong load-bearing capacity, avoiding the disadvantages of high-speed heavy-load planetary bearings and weak dynamic balance of the planetary carrier in NGW, thus improving overall reliability. Attached Figure Description

[0023] Figure 1 A schematic diagram of a transmission structure according to one embodiment of the present utility model;

[0024] Figure 2 This is a schematic diagram of the motor unit structure in one embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of a two-stage deceleration mechanism in one embodiment of the present invention.

[0026] In the diagram: 11. Motor stator; 12. Motor rotor; 13. Drive shaft; 21. Input shaft; 22. External gear; 23. Internal gear ring; 24. Pin; 25. First-stage output disc; 31. Second-stage input gear; 32. Second-stage output gear; 33. Output shaft. Detailed Implementation

[0027] Example:

[0028] The following is in conjunction with the appendix Figure 1-3 The present invention will be described in further detail below.

[0029] Low-tooth-difference wheel-side motors, such as Figure 1As shown, its housing contains a motor unit, a first-stage reduction mechanism, and a second-stage reduction mechanism connected in sequence. The motor unit is the output unit. The first-stage reduction mechanism converts high-speed input into low-speed, high-torque rotary motion. The second-stage reduction mechanism performs secondary reduction and torque increase and engages with the vehicle wheel hub, ultimately driving the vehicle wheel hub to rotate at an extremely low speed. The drive shaft 13 of the motor unit is connected to the input shaft 21 of the first-stage reduction mechanism. The first-stage reduction mechanism is an involute planetary structure with a small tooth difference and a pin-type output mechanism. A second-stage input gear 31 is fixed on the first-stage output disk 25 of the first-stage reduction mechanism. The second-stage input gear 31 meshes with the second-stage output gear 32 of the second-stage reduction mechanism. An output shaft 33 passes through the second-stage output gear 32 and engages with the vehicle wheel hub.

[0030] like Figure 2 As shown, the motor unit includes a motor stator 11, a motor rotor 12, and a drive shaft 13. The motor stator 11 is fixed inside the motor housing, and the drive shaft 13 passes through the motor rotor 12. When the motor stator 11 is energized, it drives the motor rotor 12 and the drive shaft 13 to rotate synchronously, providing high-speed input to the first-stage reduction mechanism.

[0031] like Figure 3 As shown, the first-stage reduction mechanism includes an input shaft 21, an external gear 22, an internal gear ring 23, several pins 24, and a first-stage output disk 25. The overall structure is an involute planetary gear with a small tooth difference. The input shaft 21 is fixedly connected to the drive shaft 13, with an eccentric portion at the other end. The external gear 22 has a through slot in its center and connects to the eccentric portion of the input shaft 21 via a mounted bearing sleeve. The internal gear ring 23 is fixedly mounted inside the motor housing or on the vehicle wheel hub bracket. The external gear 22 and the internal gear ring 23 mesh internally with a tooth difference of 1 to 4 teeth, with the optimal tooth difference being 1 tooth, at which point the single-stage transmission ratio is maximized. The external gear 22 has circumferentially distributed and through-hole output circular holes, and the first-stage output disk 25 has corresponding circular holes. The first-stage output disk 25 is connected to the external gear 22 via pins 24, forming a pin-type output mechanism. Pins 24 are fitted with pin sleeves within the corresponding circular holes to reduce wear and improve service life. The input shaft 21 drives the external gear 22, the first-stage output disc 25, and the second-stage input gear 31 synchronously along the internal gear ring 23 in an involute planetary transmission with a small tooth difference via an eccentric part. The transmission ratio i1 of the first-stage reduction mechanism is 30 to 100. The first-stage output disc 25 is the output component of the entire first-stage transmission, and the second-stage input gear 31 is coaxially connected to it to ensure the certainty of the power transmission path.

[0032] like Figure 3As shown, the two-stage reduction mechanism also includes a two-stage output gear 32 and an output shaft 33. The output shaft 33 is connected to the vehicle wheel hub, and the other end of the output shaft 33 is fixedly equipped with the two-stage output gear 32. The two-stage output gear 32 meshes with the two-stage input gear 31. The two-stage input gear 31 drives the two-stage output gear 32 and the output shaft 33 to rotate synchronously, and the output shaft 33 outputs to the vehicle wheel hub. The diameter of the two-stage output gear 32 is larger than that of the two-stage input gear 31, that is, the entire two-stage transmission is a reduction and torque increase transmission; the transmission ratio i2 of the two-stage reduction mechanism is 3 to 5.

[0033] The entire design uses an involute planetary gear transmission with a small tooth difference as the first stage of reduction and a cylindrical gear transmission as the second stage of reduction, connecting them in series in the basic architecture of the wheel-side motor. This directly replaces the complex transmission schemes of traditional two-stage NGW planetary gears or NGW parallel shafts, achieving a high speed ratio and high rigidity with a fixed internal gear ring 23 and a pin-type output structure. Compared to traditional multi-stage NGW transmission systems, the proposed solution significantly reduces the number of parts, simplifies the assembly process, and lowers costs. The first-stage reduction achieves a transmission ratio far exceeding that of a single-stage NGW, while the second-stage reduction moderately amplifies the ratio, making it easier to reach a total transmission ratio of several hundred. Furthermore, the speed ratio distribution is more reasonable and flexible. In contrast, the speed ratio of each stage in a multi-stage NGW system is generally less than 10, limiting the total speed ratio, and requiring more complex gear parameter designs to achieve a high speed ratio. The overall axial dimension is extremely short, and even with the addition of a cylindrical gear, the compactness can be improved through radial layout. The small tooth difference transmission has a large number of meshing teeth, and the pin-type output has a large bearing area and high rigidity. The torsional stiffness and impact resistance of the overall transmission structure are superior to multi-stage NGW systems with long transmission chains and numerous parts, and the technology is also more mature and reliable.

[0034] The motor rotor 12 inputs high-speed rotation to the first-stage reduction mechanism via the drive shaft 13. Utilizing the involute curve's low-tooth-difference working principle, the high-speed input is converted into low-speed, high-torque rotary motion of the first-stage output disc 25. This motion is then further reduced and increased in torque by the second-stage transmission gear, ultimately driving the vehicle wheel hub to rotate at an extremely low speed. Specifically, when the motor stator 11, fixed within the motor housing, is energized, the motor rotor 12 begins to rotate, driving the input shaft 21 to rotate the external gear 22. The internal gear ring 23 remains fixed, and the translational motion of the external gear 22 is transmitted to the first-stage output disc 25 via the pin 24, completing the first-stage reduction. The second-stage input gear 31, connected to the first-stage output disc 25, transmits the reduced motion to the meshing second-stage output gear 32. The second-stage output gear 32 drives the output shaft 33 to rotate the vehicle wheel hub, completing the second-stage reduction.

[0035] It should be noted that this specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

Claims

1. A low-tooth differential wheel-side motor, characterized in that: It includes a motor unit, a first-stage reduction mechanism, and a second-stage reduction mechanism that are driven in sequence, wherein the second-stage reduction mechanism is connected to and drives the vehicle wheel hub to rotate; The drive shaft (13) of the motor unit is connected to the input shaft (21) of the first-stage reduction mechanism. The first-stage reduction mechanism is an involute planetary structure with a small tooth difference and a pin-type output mechanism. A second-stage input gear (31) is fixedly provided on the first-stage output disk (25) of the first-stage reduction mechanism. The second-stage input gear (31) meshes with the second-stage output gear (32) of the second-stage reduction mechanism. An output shaft (33) passes through the second-stage output gear (32) and is connected to the vehicle wheel hub.

2. The low-tooth-difference wheel-side motor according to claim 1, characterized in that: The motor unit also includes a motor stator (11) and a motor rotor (12). The motor stator (11) is fixed inside the housing of the low-tooth differential wheel motor. The drive shaft (13) passes through the motor rotor (12). The motor stator (11) is energized and drives the motor rotor (12) and the drive shaft (13) to rotate synchronously.

3. The low-tooth-difference wheel-side motor according to claim 1, characterized in that: The input shaft (21) is provided with an eccentric part; The primary reduction mechanism also includes an external gear (22), an internal gear ring (23), and a pin shaft (24) with a pin sleeve. The eccentric part on the input shaft (21) is connected to the external gear (22) through a bearing sleeve. The external gear (22) and the internal gear ring (23) mesh internally and have a difference in the number of teeth. The external gear (22) has circumferentially distributed and through output holes, and the first-stage output disk (25) has corresponding holes. The first-stage output disk (25) is connected to the external gear (22) through the pin (24) to form a pin-type output mechanism.

4. The low-tooth-difference wheel-side motor according to claim 3, characterized in that: The internal gear ring (23) is fixed inside the housing of the motor with a small tooth differential wheel or fixed on the vehicle wheel hub bracket; The difference in the number of teeth between the external gear (22) and the internal gear ring (23) is 1 to 4 teeth.

5. The low-tooth-difference wheel-side motor according to claim 3, characterized in that: The input shaft (21) drives the external gear (22), the first-stage output disk (25) and the second-stage input gear (31) to perform involute planetary transmission with small tooth difference along the internal gear ring (23) through the eccentric part.

6. The low-tooth-difference wheel-side motor according to claim 3, characterized in that: The transmission ratio i1 of the first-stage reduction mechanism is 30 to 100.

7. The low-tooth-difference wheel-side motor according to claim 1, characterized in that: The secondary input gear (31) is coaxially and fixedly connected to the primary output disk (25); The secondary output gear (32) meshes externally with the secondary input gear (31).

8. The low-tooth-difference wheel-side motor according to claim 7, characterized in that: The secondary input gear (31) drives the secondary output gear (32) and the output shaft (33) to rotate synchronously, and the output shaft (33) outputs the vehicle wheel hub.

9. The low-tooth-difference wheel-side motor according to claim 7, characterized in that: The diameter of the secondary output gear (32) is larger than that of the secondary input gear (31); The transmission ratio i2 of the secondary reduction mechanism is 3 to 5.

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