Driving assembly and gardening tool

Abstract

The utility model belongs to the technical field of motor speed reducers, and particularly relates to a driving assembly and a gardening tool. The planetary reducer comprises a shell and a planet wheel assembly installed in the shell, the power input end of the planet wheel assembly is connected with an output shaft of the motor, and the power output end of the planet wheel assembly is connected with the shell; and each gear in the planet wheel assembly is a helical gear. The motor and the helical gear planetary reducer are combined to drive the garden tool to walk, helical gear meshing is more stable and smoother, the bearing capacity is higher, data collected by the encoder is more accurate, motor current is more stable, and accurate control over movement of the driving motor by the controller is better facilitated.

Description

Technical Field

[0001] The utility model belongs to the technical field of motor reducers, and in particular relates to a driving component and a garden tool. Background Art

[0002] Garden tools can be driven by a driving motor with a reduction gear set on the vehicle body. The currently popular mechanism mainly adopts a combination of motor components and gearbox components. The motor part includes an encoder and a permanent magnet brushless DC motor, and the gearbox part includes a gear reduction mechanism. The gear reduction mechanism of existing garden tools mostly adopts spur gear transmission. Its defect is that the volume of the traditional gear reduction mechanism is large, which affects the flexibility of the garden tool. In addition, the meshing characteristics of the spur gear transmission are instantaneous meshing and instantaneous disconnection, while the gear reduction mechanism adopts multiple sets of gear meshing transmission at the same time. Moreover, due to the error of equipment processing, the accuracy of each gear is not consistent, so the gearbox of the spur gear transmission is not stable, and it will be accompanied by vibration and noise problems. The unstable operation of the gearbox will bring fluctuations to the current and operation of the motor. The encoder will cause the collected signal to be chaotic due to the unstable rotation of the motor, and the controller will reduce the control accuracy of the motor due to the fluctuation of the current waveform of the motor. Utility Model Content

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a driving component and a garden tool that can improve the motion control accuracy and smoothness.

[0004] In order to achieve the above-mentioned purpose and other related purposes, the utility model provides a driving assembly, including:

[0005] Motor;

[0006] A planetary reducer, the planetary reducer comprising a housing and a planetary gear assembly installed in the housing, the power input end of the planetary gear assembly is connected to the output shaft of the motor, and the power output end of the planetary gear assembly is connected to the housing;

[0007] Each gear in the planetary gear assembly is a helical gear.

[0008] In an optional embodiment of the utility model, the planetary gear assembly includes a first-stage planetary gear assembly and a second-stage planetary gear assembly, wherein the sun gear of the first-stage planetary gear assembly is connected to the planet carrier of the other-stage planetary gear assembly, and the sun gear and the planetary gear on the planet carrier are assembled so that the axial forces they are subjected to are in opposite directions during operation.

[0009] In an optional embodiment of the present invention, the first-stage planetary gear assembly includes a first sun gear, a first planet carrier, a first planetary gear and a first ring gear, wherein the first sun gear is connected to the output shaft of the motor, the first planet carrier is rotatably arranged relative to the outer casing of the motor, the first planetary gear is rotatably connected to the first planet carrier, the first ring gear is fixedly connected to the casing, and the first planetary gear is respectively meshed with the first sun gear and the first ring gear.

[0010] In an optional embodiment of the present invention, the second-stage planetary gear assembly includes a second sun gear, a second planet carrier, a second planetary gear and a second ring gear, wherein the second sun gear is fixedly connected to the first planet carrier, the second planet carrier is fixedly connected to the housing of the motor, the second planetary gear is rotatably connected to the second planet carrier, the second ring gear is fixedly connected to the housing, and the second planetary gear is respectively meshed with the second sun gear and the second ring gear.

[0011] In an optional embodiment of the present invention, the tooth profiles of the first planetary gear and the second sun gear have the same rotation direction.

[0012] In an optional embodiment of the present invention, the tooth profiles of the first sun gear and the second planetary gear have the same rotation direction.

[0013] In an optional embodiment of the present invention, a bearing is provided between the second planet carrier and the housing.

[0014] In an optional embodiment of the present invention, the planetary gear assembly includes a planetary gear and a planetary carrier, the planetary gear is rotatably connected to the planetary carrier, and an axial support unit is provided between the planetary gear and the planetary carrier.

[0015] In an optional embodiment of the present invention, the axial support unit includes balls arranged between the end surface of the planetary wheel and the planetary carrier, and a plurality of the balls are arranged along the circumferential direction of the planetary wheel.

[0016] In an optional embodiment of the present invention, an annular groove for accommodating the ball is provided on the end surface of the planetary wheel.

[0017] In an optional embodiment of the present invention, an annular gasket is provided on a side of each of the balls away from the planetary gear, and an end surface of the annular gasket forms a rolling fit with each of the balls.

[0018] In an optional embodiment of the present invention, a pin is provided on the planet carrier, and the planetary wheel is provided with an axial hole for the pin to pass through, and a radial support unit is provided between the inner wall of the axial hole and the pin.

[0019] In an optional embodiment of the present invention, the radial support unit includes rollers, and a plurality of the rollers are arranged along the circumferential direction of the pin shaft.

[0020] In an optional embodiment of the present invention, an encoder for monitoring the working state of the motor is further included, and the encoder and the motor are electrically connected to the controller respectively.

[0021] In an optional embodiment of the present utility model, the motor is provided with a first connection portion for connecting to a garden tool frame assembly; the housing is provided with a second connection portion for connecting to a garden tool wheel.

[0022] In order to achieve the above-mentioned purpose and other related purposes, the utility model provides a garden tool, comprising:

[0023] Frame components;

[0024] A motor, fixedly connected to the frame assembly;

[0025] A planetary reducer, comprising a housing and a planetary gear assembly installed in the housing, wherein a power input end of the planetary gear assembly is connected to an output shaft of the motor, and a power output end of the planetary gear assembly is connected to the housing; each gear in the planetary gear assembly is a helical gear;

[0026] A wheel is connected to the housing.

[0027] The technical effect of the utility model is that the utility model combines a motor with a helical gear planetary reducer to drive garden tools to move. The helical gears engage more smoothly and have a stronger carrying capacity. The data collected by the encoder is more accurate, the motor current is more stable, and it is more conducive to the controller to accurately control the movement of the drive motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a three-dimensional diagram of a riding lawn mower provided by an embodiment of the utility model;

[0029] Figure 2 is an exploded view of a riding lawn mower provided by an embodiment of the utility model;

[0030] Figure 3 is a three-dimensional diagram of a drive assembly provided by an embodiment of the utility model;

[0031] Figure 4 is an exploded view of a drive assembly provided in an embodiment of the utility model;

[0032] Figure 5 It is an exploded diagram of the motor and the encoder provided in the embodiment of the utility model;

[0033] Figure 6 It is an exploded view of a planetary reducer provided in an embodiment of the utility model;

[0034] Figure 7 It is a schematic diagram of the assembly structure of the motor and the sun gear provided in the embodiment of the utility model;

[0035] Figure 8 is a three-dimensional diagram of a planetary gear assembly provided by an embodiment of the utility model;

[0036] Fig. 9 It is a schematic diagram of a three-dimensional cross-section structure of a housing provided by an embodiment of the utility model;

[0037] Fig.10 is a partial cross-sectional view of a second planet carrier provided by an embodiment of the utility model;

[0038] Fig.11 It is an exploded view of the second planet carrier and the second planet gear provided by the embodiment of the utility model;

[0039] Fig.12 It is an exploded view of the second planetary gear, the axial support unit and the radial support unit provided in the embodiment of the utility model;

[0040] Fig.13 It is an exploded view of the first planet carrier, the first planet gear and the second sun gear provided in an embodiment of the utility model;

[0041] Fig.14 It is a transmission principle diagram of a planetary reducer provided in an embodiment of the utility model;

[0042] Fig.15 It is a force principle diagram of the planetary reducer provided in the embodiment of the utility model;

[0043] Explanation of the reference numerals: 100, drive assembly; 200, chassis; 300, wheel; 10, motor; 11, encoder; 20, planetary reducer; 21, first sun gear; 22, first planet carrier; 221, first pin; 222, first ball; 223, first annular gasket; 224, first roller; 23, first planet gear; 24, first ring gear; 25, second sun gear; 26, second planet carrier; 261, second pin; 262, second ball; 263, second annular gasket; 264, second roller; 27, second planet gear; 271, annular groove; 28, second ring gear; 29, housing; 291, second connecting portion; 292, end cover; 293, first retaining spring; 294, second retaining spring; 295, bearing. DETAILED DESCRIPTION

[0044] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0045] It should be noted that the illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0046] The driving assembly provided by the utility model is suitable for gardening tools, and is particularly suitable for driving gardening tools to walk. The gardening tools described in the utility model include but are not limited to lawn mowers, snow sweepers, floor scrubbers, spreaders, micro-tillage machines, etc.

[0047] It should be understood that garden tools have high requirements for movement flexibility, so their lateral width is generally narrow. The drive assembly consisting of the motor and the planetary reducer provided by the utility model can be installed in the axial space of the wheel, thereby making full use of the lateral space of the garden tool and improving the flexibility of the movement of the garden tool.

[0048] The gear reducers in existing garden tools are generally simpler in structure because of limited space. However, the meshing characteristics of spur gear transmission are instantaneous meshing and instantaneous disconnection. The planetary gear train uses multiple sets of gear meshing transmission at the same time. In addition, due to the error of equipment processing, the accuracy of each gear is not consistent, so the gearbox of spur gear transmission is not stable, and there will be vibration and noise problems. The unstable operation of the gearbox will cause fluctuations in the current and operation of the motor. The encoder will collect chaotic signals due to the unstable rotation of the motor, and the controller will reduce the control accuracy of the motor due to the fluctuation of the current waveform of the motor.

[0049] In response to the above problems, the utility model combines a planetary reducer with a motor, and sets the gears in the planetary reducer as helical gears. Compared with traditional gear reducers, the planetary reducer has a more compact structure, the helical gear meshing is smoother and more stable, the load-bearing capacity is stronger, the data collected by the encoder is more accurate, the motor current is more stable, and it is more conducive to the controller to accurately control the movement of the drive motor; at the same time, in order to overcome the problem of limited space of the planetary reducer, the utility model provides a new axial support unit to support the helical gears, thereby realizing the stable operation of the helical gears in a small space.

[0050] See also Figure 1-15 As shown, the technical solution of the utility model is described in detail below in conjunction with specific embodiments.

[0051] See also Figure 1 , 2 As shown, an embodiment of the utility model provides a riding lawn mower, which is a garden tool for mowing large areas of lawns and is widely used in parks, stadiums, golf courses, farmlands and other places. The riding lawn mower mainly includes a frame assembly, a drive assembly 100 and a cutting assembly, wherein the frame assembly may further include a chassis 200 and wheels 300, and the chassis 200 is usually made of steel or cast iron material, and is used to support various components of the upper part of the lawn mower; the frame assembly may have a seat and a comfortable joystick, and the operator may sit on the seat and use the joystick to control the movement and cutting behavior of the lawn mower; in addition, the frame assembly may also be provided with a steering system, and the turning radius may be adjusted as needed to adapt to the shape and size of the lawn; the cutting component may be composed of a mowing blade, and the mowing blade may adjust the blade height according to the height of the lawn to ensure the best cutting effect in different occasions.

[0052] It should be noted that the utility model is mainly an improvement made to the garden drive assembly 100, so the following embodiments will describe the drive assembly 100 in detail, and the specific structure and working principle of the frame assembly and the cutting assembly will not be repeated; in addition, the drive assembly 100 of the utility model is not limited to use in lawn mowers. The drive assembly 100 of the utility model is theoretically applicable to any wheel-driven garden tool.

[0053] See also Figure 3-5 As shown, the drive assembly 100 includes a motor 10 and a planetary reducer 20; in a specific embodiment, the motor 10 can be, for example, a brushless DC motor, and the motor 10 can be installed on the frame assembly through a first connection portion. The garden tool can realize forward, backward, steering, and turning around on the spot through the forward and reverse rotation of the motor 10. These processes require precise control of the torque and speed of the motor 10. For this purpose, an encoder 11 can be installed on the motor 10, and the motor 10 and the encoder 11 are connected to the controller. The encoder 11 is a device that monitors and feedbacks the movement of the motor 10 in real time by converting motion information into electrical signals; it can measure information such as the position, speed, and direction of rotation of the motor 10, and transmit this information to the controller so that the controller can accurately control and adjust the movement of the motor 10; the encoder 11 can improve the motion performance and accuracy of the motor 10, enhance the control reliability of the motor 10, and achieve efficient and stable motor motion control.

[0054] See also Figure 6 As shown, the planetary reducer 20 includes a housing 29 and a planetary gear assembly installed in the housing 29. The power input end of the planetary gear assembly is connected to the output shaft of the motor 10, and the power output end of the planetary gear assembly is connected to the housing 29. The housing 29 is provided with a second connecting portion 291 for connecting the wheel 300; each gear in the planetary gear assembly is a helical gear. Compared with the traditional spur gear planetary reducer 20, the helical gear meshes more smoothly and has a stronger load-bearing capacity. The data collected by the encoder 11 is more accurate, and the current of the motor 10 is more stable, which is more conducive to the controller to accurately control the movement of the drive motor 10.

[0055] See also Figure 6-9 As shown in , 14 and 15, in an optional embodiment of the utility model, the planetary gear assembly includes a first-stage planetary gear assembly and a second-stage planetary gear assembly, wherein the sun gear of the first-stage planetary gear assembly is connected to the planet carrier of the other-stage planetary gear assembly, and the sun gear and the planetary gear on the planet carrier are assembled so that the axial forces they are subjected to are in opposite directions when they are running.

[0056] It should be understood that helical gears will generate axial loads during the transmission process. When there are multiple helical gears on the same component, if the axial loads on these helical gears are in the same direction, these axial loads will be superimposed on each other, thereby affecting the reliability of the connection between this component and other components. If the axial loads on these helical gears are in opposite directions, part of the axial loads will offset each other, thereby improving the reliability of this component.

[0057] In the planetary gear assembly provided in this embodiment, at least one planetary carrier includes both a sun gear and a planetary gear. The utility model sets the sun gear and the planetary gear on the planetary carrier so that the axial loads face in opposite directions, so that the axial loads of the two offset each other, thereby improving the reliability of the planetary carrier structure. It should be understood that the axial load on the helical gear is related to the rotation direction of the helical gear tooth profile and the rotation direction of the helical gear itself, so when the rotation directions of the sun gear and the planetary gear are opposite, the tooth profile rotation directions of the two should be the same; conversely, when the rotation directions of the sun gear and the planetary gear are the same, the tooth profile rotation directions of the two should be opposite.

[0058] See also Figure 6-9As shown in Figures 1 and 14, in an optional embodiment of the utility model, the first-stage planetary gear assembly includes a first sun gear 21, a first planetary carrier 22, a first planetary gear 23 and a first ring gear 24, wherein the first sun gear 21 is connected to the output shaft of the motor 10, the first planetary carrier 22 is rotatably arranged relative to the outer casing of the motor 10, the first planetary gear 23 is rotatably connected to the first planetary carrier 22, the first ring gear 24 is fixedly connected to the housing 29, and the first planetary gear 23 is respectively meshed with the first sun gear 21 and the first ring gear 24; the second-stage planetary gear assembly includes a second sun gear 25, a second planetary carrier 26, a second planetary gear 27 and a second ring gear 28, wherein the second sun gear 25 is fixedly connected to the first planetary carrier 22, the second planetary carrier 26 is fixedly connected to the outer casing of the motor 10, the second planetary gear 27 is rotatably connected to the second planetary carrier 26, the second ring gear 28 is fixedly connected to the housing 29, and the second planetary gear 27 is respectively meshed with the second sun gear 25 and the second ring gear 28.

[0059] Based on the above embodiment, the first planetary gear 23 and the second sun gear 25 are equivalent to being installed on the same component, that is, both are installed on the first planetary carrier 22 at the same time. Fig.14 As shown in the transmission principle, the rotation direction of the first planetary gear 23 and the rotation direction of the second sun gear 25 should be opposite, so the tooth profiles of the first planetary gear 23 and the second sun gear 25 have the same rotation direction. Fig.15 As shown, the axial load on the first planetary gear 23 is F2, and the axial load on the second sun gear 25 is F1, and the axial loads of the two are offset, thereby improving the stability of the first planetary carrier 22; in addition, the first sun gear 21 and the second planetary gear 27 are equivalent to being installed on the same component, that is, both are installed on the motor 10, according to Fig.14 As shown in the transmission principle, the rotation direction of the first sun gear 21 and the rotation direction of the second planetary gear 27 should be opposite, so the tooth profiles of the first sun gear 21 and the second planetary gear 27 have the same rotation direction. Fig.15 As shown, the axial load on the first sun gear 21 is F3, and the axial load on the second planetary gear 27 is F4, and the axial loads of the two are offset, thereby improving the stability of the motor 10.

[0060] In this embodiment, the first sun gear 21 is used as the power input end of the planetary reducer 20, and the second ring gear 28 is used as the power output end of the planetary reducer 20, thereby realizing two-stage reduction. It should be noted that the movement mode of each gear in the planetary reducer 20 of the utility model is not unique. For example, in some other embodiments, one of the planet carriers can be used as the power input end, one of the ring gears can be used as the power output end, or one of the sun gears can be used as the power input end, and one of the planet carriers can be used as the power output end.

[0061] In addition, the planetary reducer 20 of the present invention is not limited to two-stage reduction, but can increase or decrease the reduction level according to actual needs. For example, in some other embodiments, it can also be set to one-stage reduction or three-stage reduction.

[0062] See also Fig. 9 As shown, in an optional embodiment of the present invention, a bearing 295 is provided between the second planet carrier 26 and the housing 29. The second planet carrier 26 is fixedly connected to the motor 10, so the bearing 295 provided between the second planet carrier 26 and the housing 29 can improve the support of the housing 29.

[0063] See also Figure 10-13 As shown, since there is axial load on each gear of the helical gear planetary reducer, it is necessary to provide axial support for each gear. Also, since the internal space of the planetary reducer 20 is limited, it is not convenient to set a thrust bearing. Therefore, the utility model also provides a new axial support unit, which is particularly suitable for installation between the planetary gear and the planetary carrier.

[0064] In an optional embodiment, the axial support unit may include balls arranged between the end face of the planetary wheel and the planetary carrier, and a plurality of balls are arranged along the circumferential direction of the planetary wheel. The balls can provide axial support force while maintaining smooth rotational cooperation between the planetary wheel and the planetary carrier. Furthermore, an annular groove for accommodating the balls may be provided on the end face of the planetary wheel, and the balls may be accommodated in the annular groove to further save the axial space of the planetary reducer 20. In an optional embodiment of the utility model, an annular gasket is provided on the side of each ball away from the planetary wheel, and the end face of the annular gasket forms a rolling cooperation with each ball. The annular gasket can be made of wear-resistant material, and the annular gasket can protect the end face of the planetary carrier to prevent the end face of the planetary carrier from wear.

[0065] In an optional embodiment of the utility model, a pin is provided on the planet carrier, a shaft hole is provided on the planet wheel for the pin to pass through, and a radial support unit is provided between the inner wall of the shaft hole and the pin. In a preferred embodiment, the radial support unit includes a roller, and a plurality of rollers are arranged along the circumferential direction of the pin. In some other embodiments, the roller can also be replaced by a common bearing.

[0066] See also Figure 10-12 As shown, taking the second planetary carrier 26 and the second planetary gear 27 as an example, the second planetary carrier 26 is provided with a second pin shaft 261, the second planetary gear 27 is loosely sleeved on the second pin shaft 261, and a second roller 264 is provided between the second planetary gear 27 and the second pin shaft 261, an annular groove 271 is provided on the end surface of the second planetary gear 27, a second ball 262 is provided in the annular groove 271, a second annular gasket 263 is provided on the outer side of the second ball 262, and the second annular gasket 263 is in contact with the end surface of the second planetary carrier 26.

[0067] Likewise, see Fig.13 As shown, the first planetary carrier 22 is provided with a first pin shaft 221, the first planetary gear 23 is loosely sleeved on the first pin shaft 221, and a first roller 224 is provided between the first planetary gear 23 and the first pin shaft 221, a first ball 222 is provided on the end face of the first planetary gear 23, a first annular gasket 223 is provided on the outer side of the first ball 222, and the first annular gasket 223 is in contact with the end face of the first planetary carrier 22.

[0068] See also Figure 6 As shown, in order to facilitate the assembly of the planetary reducer 20, an opening can be provided on the side of the housing 29 away from the motor 10, and an end cover 292 can be provided at the opening. The end cover 292 and the housing 29 can be connected, for example, by a first retaining spring 293. Of course, in some other embodiments, the end cover 292 can also be connected to the housing 29 by bolts. Further, in order to achieve axial limitation between the housing 29 and the second planet carrier 26, a second retaining spring 294 can be provided between the second planet carrier 26 and the housing 29.

[0069] To sum up, the utility model combines a motor with a helical gear planetary reducer to drive garden tools to move. The helical gears engage more smoothly and have a stronger load-bearing capacity. The data collected by the encoder is more accurate, the motor current is more stable, and it is more conducive to the controller's precise control of the movement of the drive motor. The utility model sets the two helical gears on the same component so that the axial loads face opposite directions, so that the axial loads of the two offset each other, thereby improving the stability of the reducer structure. The axial support unit provided by the utility model saves axial space while achieving axial support for the planetary gear, making the structure of the planetary reducer more compact.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

[0071] In the description herein, many specific details, such as examples of components and / or methods, are provided to provide a complete understanding of the embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention may be practiced without one or more specific details or by other devices, systems, components, methods, components, materials, parts, etc. In other cases, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of the embodiments of the present invention.

Claims

1. A drive assembly, characterized in that: include: Motor; A planetary reducer, the planetary reducer comprising a housing and a planetary gear assembly installed in the housing, the power input end of the planetary gear assembly is connected to the output shaft of the motor, and the power output end of the planetary gear assembly is connected to the housing; Each gear in the planetary gear assembly is a helical gear.

2. The drive assembly according to claim 1, characterized in that: The planetary gear assembly includes a first-stage planetary gear assembly and a second-stage planetary gear assembly, wherein the sun gear of the first-stage planetary gear assembly is connected to the planet carrier of the other-stage planetary gear assembly, and the sun gear and the planetary gear on the planet carrier are assembled so that the axial forces they are subjected to are in opposite directions when they are running.

3. The drive assembly according to claim 2, characterized in that: The first-stage planetary gear assembly includes a first sun gear, a first planet carrier, a first planetary gear and a first ring gear, wherein the first sun gear is connected to the output shaft of the motor, the first planet carrier is rotatably arranged relative to the outer casing of the motor, the first planetary gear is rotatably connected to the first planet carrier, the first ring gear is fixedly connected to the casing, and the first planetary gear is respectively meshed with the first sun gear and the first ring gear.

4. The drive assembly according to claim 3, characterized in that: The second-stage planetary gear assembly includes a second sun gear, a second planet carrier, a second planetary gear and a second ring gear, wherein the second sun gear is fixedly connected to the first planet carrier, the second planet carrier is fixedly connected to the housing of the motor, the second planetary gear is rotatably connected to the second planet carrier, the second ring gear is fixedly connected to the housing, and the second planetary gear is respectively meshed with the second sun gear and the second ring gear.

5. The drive assembly according to claim 4, characterized in that: The first planetary gear and the second sun gear have the same tooth profile rotation direction.

6. The drive assembly according to claim 4, characterized in that: The first sun gear and the second planet gear have the same tooth rotation direction.

7. The drive assembly according to claim 4, characterized in that: A bearing is provided between the second planet carrier and the housing.

8. The drive assembly according to claim 1, characterized in that: The planetary wheel assembly comprises a planetary wheel and a planetary carrier. The planetary wheel is rotatably connected to the planetary carrier, and an axial support unit is arranged between the planetary wheel and the planetary carrier.

9. The drive assembly according to claim 8, characterized in that: The axial support unit includes balls disposed between the end surface of the planetary gear and the planetary carrier, and a plurality of the balls are arranged along the circumferential direction of the planetary gear.

10. The drive assembly according to claim 9, characterized in that An annular groove for accommodating the balls is provided on the end surface of the planetary gear.

11. The drive assembly according to claim 9, characterized in that: An annular gasket is provided on one side of each ball away from the planetary gear, and the end surface of the annular gasket forms a rolling fit with each ball.

12. The drive assembly according to claim 8, characterized in that The planet carrier is provided with a pin shaft, the planet wheel is provided with an axial hole for the pin shaft to pass through, and a radial support unit is provided between the inner wall of the axial hole and the pin shaft.

13. The drive assembly according to claim 12, characterized in that The radial support unit includes rollers, and a plurality of the rollers are arranged along a circumferential direction of the pin shaft.

14. The drive assembly according to claim 1, characterized in that It also includes an encoder for monitoring the working state of the motor, and the encoder and the motor are electrically connected to the controller respectively.

15. The drive assembly according to claim 1, characterized in that The motor is provided with a first connection part for connecting to a garden tool frame assembly; the housing is provided with a second connection part for connecting to a garden tool wheel.

16. A garden tool, characterized in that: include: Frame components; A motor, fixedly connected to the frame assembly; A planetary reducer, comprising a housing and a planetary gear assembly installed in the housing, wherein a power input end of the planetary gear assembly is connected to an output shaft of the motor, and a power output end of the planetary gear assembly is connected to the housing; each gear in the planetary gear assembly is a helical gear; A wheel is connected to the housing.

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