drive mechanism

Abstract

The utility model discloses a drive mechanism, including support, motor, with motor drive connection's planetary reducer, with planetary reducer drive connection's gear reducer and with gear reducer fixed connection's wheel assembly, support includes the support part for the joint planetary reducer, and planetary reducer includes gear ring, and motor includes the casing, and gear ring, support part and casing are connected gradually from inside to outside in the radial direction of gear ring, and the thermal expansion coefficient of support part is greater than the thermal expansion coefficient of gear ring and casing, and the casing can be in the radial hindering effect of support expansion process to support, so that the outer ring of gear ring and support part keep interference joint state. The utility model can reduce the expansion gap between support and gear ring, reduce the risk of gear ring slip phenomenon appearance, and the operation stability is good.

Description

TECHNICAL FIELD

[0001] The utility model relates to a fork truck drive mechanism technical field, in particular to a drive mechanism. BACKGROUND

[0002] In order to guarantee the requirement of small volume and high speed ratio of drive mechanism, the motor, planetary reducer and gear reducer are usually used in the prior art to meet the requirement. Generally, the planetary reducer is arranged between the motor and the gear reducer. Through the above mechanical cooperation, the drive mechanism has the operation characteristic of high rotating speed, and meanwhile brings the working environment of fast temperature rise and high temperature, which can cause certain disturbance to the operation stability of the planetary reducer, one of which is that the loose phenomenon is prone to occur at the connecting part of the gear ring and the support in the planetary reducer, because the support is made of aluminum material, and the gear ring is made of steel material, the expansion coefficient of aluminum is greater than that of iron, so that the interference amount between the gear ring and the support is reduced when the temperature rises, and the gear ring can slip when rotating at high speed, resulting in poor operation stability. SUMMARY

[0003] In view of the defects of the prior art, the utility model provides a drive mechanism, which can reduce the expansion gap between the support and the gear ring, reduce the risk of gear ring slipping and has good operation stability.

[0004] The utility model discloses a technical scheme as follows:

[0005] A drive mechanism, characterized in that it comprises a support, a motor, a planetary reducer in transmission connection with the motor, and a gear reducer in transmission connection with the planetary reducer, the support comprises a supporting part for connecting the planetary reducer, the planetary reducer comprises a gear ring, the motor comprises a casing, the gear ring, the supporting part and the casing are sequentially connected from inside to outside in the radial direction of the gear ring, and the thermal expansion coefficient of the supporting part is greater than that of the gear ring and the casing, the casing can hinder the radial expansion of the support during the heating process, so that the outer ring of the gear ring and the supporting part are in interference connection.

[0006] Further, the gear ring is made of steel material, and the outer ring of the gear ring is in interference connection with the support.

[0007] Further, the support is made of aluminum material, and the outer wall of the support is provided with a first step part, the casing is made of steel material, and the inner wall of the casing is provided with a second step part matched with the first step part.

[0008] Further, the first axial connection part and the first radial connection part formed between the first step part and the second step part are gap matched.

[0009] Further, the first axial connection formed between the first step portion and the second step portion is a clearance fit, and the first radial connection formed between the first step portion and the second step portion is an interference fit.

[0010] Further, the radial step surfaces of the first step portion and the second step portion are polished surfaces.

[0011] Further, the outer ring of the gear ring is uniformly provided with a plurality of splines, and the inner wall of the support fills the gap between the adjacent two teeth of the spline in the interference fit by using metal fluidity.

[0012] Further, the planetary reducer further comprises a plurality of planet gears and planet shafts, the plurality of planet gears are simultaneously engaged with the inner ring gear of the gear ring, and the planet gears and the planet shafts are connected through a needle bearing.

[0013] Further, the planetary reducer further comprises a first planet carrier, a second planet carrier and a cover shell, the cover shell is made of aluminum, the cover shell is fixedly connected with the support and covers the outside of the planetary reducer, the first planet carrier and the second planet carrier are respectively fixed at both ends of the planet shaft, the first planet carrier is connected with the cover shell through a first deep groove ball bearing, and the second planet carrier is connected with the support through a second deep groove ball bearing.

[0014] Further, the outer ring of the first deep groove ball bearing and the second deep groove ball bearing is sleeved with a sealing ring.

[0015] Further, the support has a third step portion, the housing has a fourth step portion, and the projection of the second deep groove ball bearing in the axial direction at least partially or entirely falls in the projection of the third step portion, so that in the expansion process, the fourth step portion can also limit the bearing chamber of the second deep groove ball bearing formed by the support, so that the bearing chamber can also maintain a stable form during the heating process.

[0016] Further, the second axial connection formed between the third step portion and the fourth step portion and the second radial connection are both clearance fits.

[0017] Further, the second axial connection formed between the third step portion and the fourth step portion is a clearance fit, and the second radial connection formed between the third step portion and the fourth step portion is an interference fit.

[0018] Further, the radial step surfaces of the third step portion and the fourth step portion are polished surfaces.

[0019] Further, it further comprises a wheel assembly fixedly connected with the gear reducer, the wheel assembly comprises a tire, the outer ring of the tire is provided with a plurality of left patterns and a plurality of right patterns, the plurality of left patterns and the plurality of right patterns are uniformly distributed along the circumference of the tire, and the plurality of left patterns and the plurality of right patterns are distributed in a staggered manner.

[0020] Further, the angle formed between the left pattern and the right pattern relative to the axis is between 0-10°; or the angle formed between the left pattern and the right pattern is between 160-180°, so as to improve the grip strength.

[0021] Further, the outer ring of the tire is further provided with an annular groove, and the annular groove is located between the left pattern and the right pattern.

[0022] Further, the planetary reducer further comprises a sun gear, the sun gear is integrally formed on the rotating shaft of the motor, and the outer ring of the sun gear is engaged with the plurality of planetary gear wheels.

[0023] Further, the motor further comprises a stator, a rotor and an end cover, the end cover is fixed to the end of the shell away from the planetary reducer, the stator is fixedly connected to the shell and located outside the rotor, and the rotor is interference-fitted with the rotating shaft.

[0024] Further, the third deep groove ball bearing is connected between one end of the rotating shaft and the shell, and the first ball bearing is connected between the other end of the rotating shaft and the end cover.

[0025] Further, the gear reducer comprises a first driving wheel interference-fitted with the first planet carrier, a first driven wheel engaged with the first driving wheel, a second driving wheel coaxially and fixedly connected with the first driven wheel, and a second driven wheel engaged with the second driving wheel, the second driven wheel is interference-fitted with the wheel shaft in the wheel assembly.

[0026] Further, the gear reducer further comprises a connecting shaft, a second ball bearing and a third ball bearing, the first driven wheel and the second driving wheel are both interference-fitted with the connecting shaft, one end of the connecting shaft is connected with the shell through the second ball bearing, and the other end of the connecting shaft is connected with the support through the third ball bearing.

[0027] Further, the motor and the gear reducer are respectively located on opposite sides of the support in the axial direction; the motor is located on the inner side of the support, so that the inner side installation space can be fully utilized; the gear reducer is located on the outer side of the support, and the motor, the support and the gear reducer are distributed in the radial direction, so that the space occupation volume of the driving mechanism assembly can be reduced.

[0028] Further, the support is formed with a single-side supporting arm, and the wheel assembly is located on the inner side of the single-side supporting arm.

[0029] Further, the support is formed with an assembly part matched with an external mechanism, and a fixed end of the assembly part is connected with the single-side supporting arm.

[0030] Compared with the prior art, the utility model has the advantages that:

[0031] By setting the gear ring, support part and the shell in the radial direction from inside to outside in turn, and using the different selection of expansion coefficient, the concentricity can be ensured while meeting the support strength, weight reduction and other purposes. Specifically, in the case of temperature rise in the working process, the expansion coefficients of the shell and the gear ring are smaller than that of the support part, so in the process of thermal expansion, the shell will hinder the outward expansion trend of the support part in the radial direction, thereby indirectly reducing the expansion gap between the gear ring and the support part, that is, ensuring that the change of the interference between the gear ring and the support part is basically unchanged, thereby finally reducing the risk of circumferential slip phenomenon of the gear ring in the process of cooperating with the support part. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Structure diagram of driving mechanism;

[0033] Figure 2 Front view of driving mechanism;

[0034] Figure 3 Figure 2 Sectional view along A-A;

[0035] Figure 4 Figure 3 Enlarged view of B part;

[0036] Figure 5 Partial exploded view of planetary reducer;

[0037] Figure 6 Partial structure exploded view of planetary reducer;

[0038] Figure 7 Partial structure diagram of driving mechanism;

[0039] Figure 8 Partial structure diagram of wheel assembly.

[0040] ​​1, support; 10, first step portion; 11, support portion; 12, third step portion; 13, single-side support arm; 2, motor; 20, casing; 200, second step portion; 201, abutting end face; 202, fourth step portion; 21, rotating shaft; 22, stator; 23, rotor; 24, end cover; 3, planetary reducer; 30, gear ring; 300, spline; 31, planetary gear; 32, planetary shaft; 33, needle bearing; 34, first planetary carrier; 35, second planetary carrier; 36, sun gear; 4, gear reducer; 40, first driving wheel; 41, first driven wheel; 42, second driving wheel; 43, second driven wheel; 44, connecting shaft; 45, second ball bearing; 46, third ball bearing; 5, wheel assembly; 50, tire; 51, left pattern; 52, right pattern; 53, annular groove; 54, wheel shaft; 540, mounting plate; 55, wheel hub; 6, first axial connection; 60, second axial connection; 7, first radial connection; 70, second radial connection; 8, cover; 90, first deep groove ball bearing; 91, second deep groove ball bearing; 92, third deep groove ball bearing; 93, first ball bearing. DETAILED DESCRIPTION

[0041] The utility model technical scheme will be further described in detail below in combination with the preferred embodiments and the drawings. In the description of the utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship shown in the drawings. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included at least one of the features. In the description of the utility model, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited. The embodiments described below with reference to the drawings are exemplary and are intended to explain the utility model, and cannot be understood as limiting the utility model.

[0042] As Figures 1-8As shown, the utility model discloses a drive mechanism, specifically applied to fork truck, specifically includes support 1, motor 2, with motor 2 transmission connection's planetary reducer 3, with planetary reducer 3 transmission connection's gear reducer 4 and with gear reducer 4 fixed connection's wheel assembly 5, support 1 is motor 2, planetary reducer 3, gear reducer 4 and wheel assembly 5 provide support connection support.Motor 2 and gear reducer 4 are respectively located on the opposite sides of support 1 in the axial direction;Motor 2 is located in the inner side of support 1, can make full use of the inside installation space;Gear reducer 4 is located on the outer side of support 1, motor 2, support 1 and gear reducer 4 radially distribute, can reduce the space occupation volume of drive mechanism assembly.

[0043] As Figure 3 And Figure 4 As shown, motor 2 includes casing 20, shaft 21, stator 22, rotor 23 and end cover 24, shaft 21 extends along the horizontal direction.End cover 24 is fixed at the end of casing 20 away from planetary reducer 3, stator 22 is fixedly connected with casing 20 and located at the outer side of rotor 23, rotor 23 is interference-fitted with shaft 21, and the end of shaft 21 is connected with casing 20 through third deep groove ball bearing 92, and the other end of shaft 21 is connected with end cover 24 through first ball bearing 93.Using third deep groove ball bearing 92 can bear axial and radial forces during the rotation of motor 2, and cooperating with first ball bearing 93 can ensure the smooth and accurate rotation of shaft 21 while reducing the cost.

[0044] As Figures 4-6 As shown, planetary reducer 3 includes gear ring 30, a plurality of planetary gears 31 and planetary shafts 32, the plurality of planetary gears 31 are simultaneously meshed with the inner ring gear of gear ring 30, and the planetary gears 31 and the planetary shafts 32 are connected through needle bearings 33.In one embodiment, the planetary gears 31 are arranged in a single-layer structure and the number is three.Each planetary gear 31 is connected with a planet carrier through a planetary shaft 32, and the needle bearings 33 arranged on the planetary shafts 32 cooperate with the planetary gears 31, which can reduce the friction loss of the planetary gears 31 during rotation.Because the planetary gears 31 are in a high-speed rotating state, reducing friction can also reduce energy loss and the temperature rise rate of lubricating oil.

[0045] The planetary reducer 3 further includes a sun gear 36, which is integrally formed on the shaft 21 of the motor 2, and the outer ring of the sun gear 36 is meshed with the plurality of planetary gears 31.It is worth noting that the sun gear 36 can also be in the form of an independent gear and be sleeved on the shaft 21 through a fastening fitting mode.The integrally formed mode is more convenient in machining process, saves the assembly process, and ensures the coaxiality between the sun gear 36 and the shaft 21.

[0046] The planetary reducer 3 further comprises a first planet carrier 34, a second planet carrier 35 and a cover 8 made of aluminum and fixedly connected with the support 1 and covering the outside of the planetary reducer 3, the first planet carrier 34 and the second planet carrier 35 are respectively fixed at the two ends of the planetary shaft 32, the first planet carrier 34 is connected with the cover 8 through a first deep groove ball bearing 90, and the second planet carrier 35 is connected with the support 1 through a second deep groove ball bearing 91. The two ends of the planet carrier are respectively provided with the first deep groove ball bearing 90 and the second deep groove ball bearing 91, which can bear axial and radial forces and ensure that the planet carrier can maintain coaxial with the rotating shaft 20 during rotation.

[0047] In the embodiment, the outer rings of the first deep groove ball bearing 90 and the second deep groove ball bearing 91 are both sleeved with sealing rings. The sealing rings are used to compensate the gap between the aluminum cover 8 and the steel first deep groove ball bearing 90 and between the aluminum support 1 and the steel second deep groove ball bearing 91 due to different expansion coefficients after heating.

[0048] As shown in Figure 4 The support 1 has a third stepped portion 12, and the casing 20 has a fourth stepped portion 202, the projection of the second deep groove ball bearing 91 in the axial direction at least partially or entirely falls in the projection of the third stepped portion 12, so that the fourth stepped portion 202 can limit the bearing chamber of the second deep groove ball bearing 91 formed by the support 1 during expansion, so that the bearing chamber can also maintain a stable form during heating.

[0049] The second axial connection 60 between the third stepped portion 12 and the fourth stepped portion 202 is a clearance fit, so as to facilitate the installation of the casing 20 on the shaft compared with the support 1 by mechanical avoidance during assembly; the second radial connection 70 between the third stepped portion 12 and the fourth stepped portion 202 is a clearance or interference fit, and the radial stepped surfaces of the third stepped portion 12 and the fourth stepped portion 202 are both polished surfaces.

[0050] As shown in Figure 4As shown, the bracket 1 includes a support portion 11 for engaging the planetary reducer 3. The gear ring 30, support portion 11, and housing 20 are connected sequentially from the inside to the outside in the radial direction of the gear ring 30. The thermal expansion coefficient of the support portion 11 is greater than that of the gear ring 30 and the housing 20. The housing 20 can radially impede the bracket 1 during thermal expansion, ensuring an interference fit between the outer ring of the gear ring 30 and the support portion 11. At high operating temperatures, the expansion coefficient of the housing 20 is less than that of the bracket 1. Therefore, during thermal expansion, the housing 20 radially impedes the outward expansion of the bracket 1, indirectly reducing the expansion gap between the gear ring 30 and the bracket 1. This ensures that the change in interference between the gear ring 30 and the bracket 1 is not too large. During the engagement of the planetary gear 31 with the gear ring 30, the gear ring 30 is subjected to circumferential force. The guarantee of interference in the above technical solution ultimately reduces the risk of circumferential slippage of the gear ring 30 during its engagement with the bracket 1. Additionally, it is worth noting that the structure with the stepped portion on the bracket 1 can effectively install the gear ring 30 and the planetary carrier, and can increase the contact area between the bracket 1 and the housing 20. As a result, during the thermal expansion of the bracket 1, the resistance force from the housing 20 is more uniform, thereby ensuring concentricity.

[0051] like Figure 4 As shown, in this embodiment, the gear ring 30 is made of steel and the outer ring of the gear ring 30 is interference-fitted with the bracket 1. The bracket 1 is made of aluminum and the outer wall of the bracket 1 is provided with a first step portion 10. The housing 20 is made of steel and the inner wall of the housing 20 is provided with a second step portion 200 that cooperates with the first step portion 10, so as to at least provide radial resistance to the bracket 1 during the thermal expansion process.

[0052] The first axial connection 6 formed between the first step portion 10 and the second step portion 200 is a clearance fit, the first radial connection 7 formed between the first step portion 10 and the second step portion 200 is a clearance or interference fit, and the radial step surfaces of the first step portion 10 and the second step portion 200 are both polished surfaces.

[0053] In one embodiment of this utility model, the axial connection (including the first axial connection 6 and the second axial connection 60) and the radial connection (including the first radial connection 7 and the second radial connection 70) formed between the bracket 1 and the housing 20 are both clearance fits. The clearance at the radial connection is within 0.015 mm. The larger clearance at the axial connection is intended to ensure that, when the housing 20 is installed from left to right, the rightmost abutment surface 201 of the housing 20 can completely fit against the bracket 1, and the clearance at the axial connection serves a mechanical clearance function.

[0054] In another embodiment of the utility model, the axial connection (including first axial connection 6 and second axial connection 60) formed between support 1 and shell 20 is clearance fit, and the radial connection (including first radial connection 7 and second radial connection 70) formed between support 1 and shell 20 is interference fit. Before the installation process, support 1 can be subjected to quick freezing process, so that support 1 and shell 20 are first clearance fit. After installation, support 1 expands outward, and the clearance fit is switched to interference fit in the radial direction, and the interference amount is between 0.1-0.2mm. The above-mentioned mode can adjust the clearance fit in the radial direction to interference fit on the basis of ensuring that shell 20 effectively docks support 1, prevent loosening during installation and operation, directly and effectively ensure the concentricity between motor 2 and support 1, and indirectly ensure the concentricity of the planet carrier. The clearance of the axial connection is still relatively large, and the purpose is that when shell 20 is installed from left to right, the rightmost abutting end face 201 of shell 20 can be completely attached to support 1, and the clearance of the axial connection plays a mechanical avoiding role.

[0055] As shown in Figure 5 In the embodiment, the outer ring of the ring gear 30 is uniformly arranged with a plurality of splines 300. The splines 300 are interference fit with the inner side wall of the support 1, wherein the ring gear 30 is a steel material, and the support 1 is an aluminum material. The above-mentioned setting can fill the gap between the adjacent two tooth portions of the spline 300 by using the metal fluidity of the inner wall of the support 1 during interference fit. At high temperature in work, the expansion coefficient of the ring gear 30 is less than that of the support 1, so that the interference amount between the ring gear 30 and the support 1 is reduced. By using the setting mode of the spline 300, the frictional resistance in the circumferential direction can be increased by the multi-surface contact of the tooth portion of the spline 300, and the frictional resistance is uniformly stressed. At the same time, the circumferential force generated by the meshing of the high-speed rotating planet wheel 31 and the ring gear 30 presses the ring gear 30, and the above-mentioned frictional resistance can preliminarily reduce the risk of slipping.

[0056] As shown in Figure 3 and Figure 7 The gear reducer 4 includes a first driving wheel 40 interference fit with the first planet carrier 34, a first driven wheel 41 gear meshing with the first driving wheel 40, a second driving wheel 42 coaxially fixedly connected with the first driven wheel 41, and a second driven wheel 43 gear meshing with the second driving wheel 42, and the second driven wheel 43 is interference fit with the wheel shaft 54 in the wheel assembly 5.

[0057] The gear reducer 4 further comprises a connecting shaft 44, a second ball bearing 45 and a third ball bearing 46, the first driven wheel 41 and the second driving wheel 42 are both in interference fit with the connecting shaft 44, one end of the connecting shaft 44 is connected with the cover 8 through the second ball bearing 45, and the other end of the connecting shaft 44 is connected with the support 1 through the third ball bearing 46.

[0058] As shown in Figure 8 , the wheel assembly 5 comprises a tire 50, and the outer ring of the tire 50 is provided with a plurality of left patterns 51 and a plurality of right patterns 52, the plurality of left patterns 51 and the plurality of right patterns 52 are uniformly distributed along the circumference of the tire 50, and the plurality of left patterns 51 and the plurality of right patterns 52 are distributed in a staggered manner. In the rotation process of the tire 50, the left pattern 51 and the right pattern 52 alternately contact the ground, ensuring that the ground can always be gripped during contact with the ground, thereby avoiding the occurrence of skidding phenomenon and ensuring the stability of the wheel rotation.

[0059] Among them, the angle formed between the left pattern 51 and the right pattern 52 relative to the axis is between 0-10°; or the angle formed between the left pattern 51 and the right pattern 52 is between 160-180°, which improves the grip strength.

[0060] As shown in Figure 8 , the outer ring of the tire 50 is further provided with an annular groove 53, and the annular groove 53 is located between the left pattern 51 and the right pattern 52. Since there may be particulate impurities on the ground of the factory, the arrangement of the left pattern 51, the right pattern 52 and the annular groove 53 can wrap the impurities to some extent, which can on the one hand avoid the elastic lifting of the wheel and unstable operation, and on the other hand reduce the risk of stone spalling to the outside, thereby ensuring safety.

[0061] As shown in Figure 3 , the support 1 forms a single-side supporting arm 13, the wheel assembly 5 is located on the inner side of the single-side supporting arm 13, the single-side supporting reduces the weight and realizes lightweight, and reduces the cost; the tire 50 is directly exposed and installed, which is more convenient than being installed between two supporting arms.

[0062] The support 1 forms a mounting portion matched with an external mechanism, and a fixed end of the mounting portion is connected with the single-side supporting arm 13.

[0063] As shown in Figure 3 , the wheel assembly 5 further comprises a hub 55, the tire 50 is fixedly sleeved on the outer side of the hub 55, and the hub 55 is fixedly connected with the wheel shaft 54. Specifically, the wheel shaft 54 extends radially on the side close to the hub 55 and has a mounting plate 540, the hub 55 is sleeved on the wheel shaft 54 and is fixedly connected with the mounting plate 540 through locking bolts.

[0064] The above-described embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but can not therefore be understood as the limitation of the utility model patent range. It should be pointed out that for ordinary skilled person in the art, without departing from the utility model concept, several deformations and improvements can be made, which belong to the protection range of the utility model. Therefore, the protection range of the utility model patent should be subject to the appended claims.

Claims

1. A drive mechanism characterized by, The support (1) includes a support part (11) for connecting the planetary reducer (3), the planetary reducer (3) includes a gear ring (30), the motor (2) includes a shell (20), the gear ring (30), the support part (11) and the shell (20) are sequentially connected from inside to outside in the radial direction of the gear ring (30), and the thermal expansion coefficient of the support part (11) is greater than the thermal expansion coefficients of the gear ring (30) and the shell (20), the shell (20) can radially hinder the support (1) during thermal expansion of the support (1), so that the outer ring of the gear ring (30) and the support part (11) are in interference fitting state.

2. The drive mechanism of claim 1, wherein, The gear ring (30) is made of steel, and the outer ring of the gear ring (30) is interference fitted with the support (1).

3. The drive mechanism of claim 1, wherein, The support (1) is made of aluminum, and the outer wall of the support (1) is provided with a first step part (10), the shell (20) is made of steel, and the inner wall of the shell (20) is provided with a second step part (200) matched with the first step part (10).

4. The drive mechanism of claim 3, wherein, The first axial connection (6) and the first radial connection (7) formed between the first step part (10) and the second step part (200) are gap fit.

5. The drive mechanism of claim 3, wherein, The first axial connection (6) formed between the first step part (10) and the second step part (200) is gap fit, and the first radial connection (7) formed between the first step part (10) and the second step part (200) is interference fit.

6. The drive mechanism of claim 3, wherein, The radial step surface of the first step part (10) and the second step part (200) is a polished surface.

7. The drive mechanism of claim 3, wherein, The outer ring of the gear ring (30) is uniformly spaced and provided with a plurality of splines (300), and the inner wall of the support (1) fills the gap between the adjacent two teeth of the spline (300) by using metal fluidity in interference fitting.

8. The drive mechanism of claim 1, wherein, The planetary reducer (3) further includes a plurality of planet wheels (31) and planet shafts (32), the plurality of planet wheels (31) are simultaneously meshed with the inner ring gear of the gear ring (30), and the planet wheels (31) and the planet shafts (32) are connected through a needle bearing (33).

9. The drive mechanism of claim 8, wherein, The planetary reducer (3) further includes a first planet carrier (34), a second planet carrier (35) and a cover shell (8), the cover shell (8) is made of aluminum, the cover shell (8) is fixedly connected with the support (1) and covers the outside of the planetary reducer (3), the first planet carrier (34) and the second planet carrier (35) are respectively fixed at both ends of the planet shaft (32), the first planet carrier (34) and the cover shell (8) are connected through a first deep groove ball bearing (90), and the second planet carrier (35) and the support (1) are connected through a second deep groove ball bearing (91).

10. The drive mechanism of claim 9, wherein, The outer rings of the first deep groove ball bearing (90) and the second deep groove ball bearing (91) are sleeved with sealing rings.

11. The drive mechanism of claim 9, wherein, The bracket (1) has a third step portion (12), the casing (20) has a fourth step portion (202), and a projection of the second deep groove ball bearing (91) in the axial direction at least partially or entirely falls within a projection of the third step portion (12), so that the fourth step portion (202) can also limit the bearing cavity of the second deep groove ball bearing (91) formed by the bracket (1) during the expansion process.

12. The drive mechanism of claim 11, wherein, The second axial connection (60) and the second radial connection (70) formed between the third step portion (12) and the fourth step portion (202) are both gap fits.

13. The drive mechanism of claim 11, wherein, The second axial connection (60) formed between the third step portion (12) and the fourth step portion (202) is a gap fit, and the second radial connection (70) formed between the third step portion (12) and the fourth step portion (202) is an interference fit.

14. The drive mechanism of claim 11, wherein, The radial step faces of the third step portion (12) and the fourth step portion (202) are both polished surfaces.

15. The drive mechanism of claim 9, wherein, The wheel assembly (5) is further connected to the gear reducer (4), and the wheel assembly (5) comprises a tire (50), the outer ring of the tire (50) is provided with a plurality of left patterns (51) and a plurality of right patterns (52), the plurality of left patterns (51) and the plurality of right patterns (52) are uniformly distributed along the circumference of the tire (50), and the plurality of left patterns (51) and the plurality of right patterns (52) are distributed in a staggered manner.

16. The drive mechanism of claim 15, wherein, The angle formed between the left pattern (51) and the right pattern (52) relative to the axis is between 0-10°; or the angle formed between the left pattern (51) and the right pattern (52) is between 160-180°.

17. The drive mechanism of claim 15, wherein, The outer ring of the tire (50) is further provided with an annular groove (53), and the annular groove (53) is located between the left pattern (51) and the right pattern (52).

18. The drive mechanism of claim 8, wherein, The planetary reducer (3) further comprises a sun gear (36), the sun gear (36) is integrally formed on the rotating shaft (21) of the motor (2), and the outer ring of the sun gear (36) is in gear meshing with the plurality of planetary gears (31).

19. The drive mechanism of claim 18, wherein, The motor (2) further comprises a stator (22), a rotor (23), and an end cover (24), the end cover (24) is fixed to one end of the casing (20) away from the planetary reducer (3), the stator (22) is fixedly connected to the casing (20) and located on the outer side of the rotor (23), and the rotor (23) is in interference fit with the rotating shaft (21).

20. The drive mechanism of claim 19, wherein, One end of the rotating shaft (21) is connected to the casing (20) through a third deep groove ball bearing (92), and the other end of the rotating shaft (21) is connected to the end cover (24) through a first ball bearing (93).

21. The drive mechanism of claim 15, wherein, The gear reducer (4) comprises a first driving wheel (40) in interference fit with the first planet carrier (34), a first driven wheel (41) in gear engagement with the first driving wheel (40), a second driving wheel (42) fixedly connected coaxially with the first driven wheel (41), and a second driven wheel (43) in gear engagement with the second driving wheel (42), the second driven wheel (43) being in interference fit with an axle (54) in the wheel assembly (5).

22. The drive mechanism of claim 21, wherein, The gear reducer (4) further comprises a connecting shaft (44), a second ball bearing (45) and a third ball bearing (46), the first driven wheel (41) and the second driving wheel (42) are both in interference fit with the connecting shaft (44), one end of the connecting shaft (44) is connected with the cover (8) through the second ball bearing (45), and the other end of the connecting shaft (44) is connected with the support (1) through the third ball bearing (46).

23. The drive mechanism of claim 1, wherein, The motor (2) and the gear reducer (4) are respectively located on opposite sides of the support (1) in the axial direction; the motor (2) is located on the inner side of the support (1), and the gear reducer (4) is located on the outer side of the support (1).

24. The drive mechanism of claim 15, wherein, The support (1) is formed with a single-side supporting arm (13), and the wheel assembly (5) is located on the inner side of the single-side supporting arm (13).

25. The drive mechanism of claim 24, wherein, The support (1) is formed with a mounting portion for interference fit with an external mechanism, and a fixed end of the mounting portion is connected with the single-side supporting arm (13). The support (1) is formed with a mounting portion for interference fit with an external mechanism, and a fixed end of the mounting portion is connected with the single-side supporting arm (13).

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