Drive device for power tool and power tool

Abstract

The utility model discloses a kind of driving device and electric tool for electric tool, including motor, speed reducer, end cover and eccentric shaft, motor has output shaft, motor gear is equipped on output shaft, speed reducer includes gear box shell and the inner tooth ring, first planet carrier, several first planet wheel, second planet carrier and five second planet wheel installed in gear box shell, first planet carrier is equipped with sun gear, motor gear is engaged with first planet wheel, sun gear is engaged with second planet wheel, end cover is located in gear box shell one end, eccentric shaft is transmission connection with second planet carrier, eccentric shaft rotation is arranged in the plunger installation cavity formed between second planet carrier and end cover, compared with the design that three planet wheels are generally used in conventional planetary gear set, the load of output end is shared by five planet wheels in this structure, effectively reduce the stress and wear of each second planet wheel, thereby greatly improve the service life and operating reliability of speed reducer with very low cost.

Description

Technical Field

[0001] This utility model relates to the field of power tool technology, and in particular to a drive device for power tools and a power tool. Background Technology

[0002] The core power transmission path of hydraulic tools (such as hydraulic wrenches and crimping machines) relies on the coordinated work of a reducer and an eccentric wheel-plunger mechanism. The power output from the motor is reduced in speed and increased in torque by the reducer, directly driving the eccentric shaft to rotate. The eccentric shaft connects to the plunger, converting the rotational motion into the reciprocating linear motion of the plunger. This draws the piston chamber to a negative pressure, thereby drawing hydraulic oil from the oil bag into the piston chamber. Combined with the one-way valve in the oil passage between the oil bag and the piston chamber, this pressurizes the piston chamber, causing low-pressure oil to enter through the one-way valve and form high-pressure oil, ultimately driving the tool's actuator to complete high-load operations. In this system, the reducer, as the only transmission component directly connected to the eccentric shaft, must simultaneously bear the torque required to continuously pressurize the eccentric shaft and the inertial impact load generated by the reciprocating motion of the plunger. Its performance directly determines the stability and efficiency of the hydraulic tool's power output.

[0003] Because the eccentric shaft is rigidly connected to the output end of the reducer, the reducer must directly bear the complex alternating load during the piston pressurization process. The instantaneous impact torque caused by the sudden pressure change in the hydraulic system and the inertial torque caused by the high-frequency reversal of the eccentric wheel-piston mechanism, the superposition of these loads, cause the reducer gears, bearings and shaft components to be in a high-stress cycle state for a long time, resulting in frequent failures such as tooth surface fatigue pitting, bearing raceway spalling and shaft bending deformation. As a key part of the service life of the entire hydraulic tool, the limited service life of the reducer prevents the hydraulic tool from achieving a breakthrough in low cost and long service life. Utility Model Content

[0004] In order to overcome at least one of the defects of the prior art, the present invention provides a drive device for power tools and a power tool, which can solve the problem of limited overall service life of reducers and the inability to achieve a technological breakthrough in low cost and long service life of reducers.

[0005] The technical solution adopted by this utility model to solve its problem is:

[0006] A drive mechanism for power tools, comprising:

[0007] An electric motor having an output shaft on which a motor gear is mounted;

[0008] A speed reducer includes a gearbox housing and an internal gear ring, a first planet carrier, a plurality of first planet gears, a second planet carrier, and five second planet gears mounted within the gearbox housing. The first planet carrier has a sun gear facing away from the first planet gears. All the first planet gears and all the second planet gears mesh with the internal gear ring. The motor gear meshes with all the first planet gears, and the gear shafts of all the first planet gears are connected to the first planet carrier. The sun gear meshes with all the second planet gears, and the gear shafts of all the second planet gears are connected to the second planet carrier.

[0009] An end cap, wherein the end cap is located at the end of the gearbox housing away from the motor;

[0010] An eccentric shaft is connected to the second planetary carrier via a transmission, and the eccentric shaft is rotatably disposed within a plunger mounting cavity formed between the second planetary carrier and the end cap.

[0011] Furthermore, the motor gear and the sun gear each have sixteen teeth, all the first planetary gears and all the second planetary gears each have fourteen teeth, and the internal gear ring has forty-four teeth.

[0012] Furthermore, the five second planetary gears are evenly distributed along the circumference of the sun gear.

[0013] Furthermore, the first planetary gear has three components.

[0014] Furthermore, the second planetary carrier is provided with a strip-shaped hole, and the eccentric shaft is provided with a flat part at one end facing the second planetary carrier, and the flat part of the eccentric shaft is installed in the strip-shaped hole.

[0015] Furthermore, the gearbox housing includes a gearbox outer shell with an opening at one end and a first bearing mounting hole at the other end, and a flange cover disposed at the opening. The flange cover is fixedly connected to the end face of the motor. One end of the eccentric shaft is fitted with a first bearing, and the eccentric shaft is rotatably mounted on the first bearing mounting hole via the first bearing. The other end of the eccentric shaft is fitted with a second bearing, and the eccentric shaft is rotatably mounted on the end cover via the second bearing.

[0016] Furthermore, the end cap is provided with a second bearing mounting hole, and the second bearing is assembled in the second bearing mounting hole.

[0017] Furthermore, the gearbox housing, and / or the flange cover, and / or the end cover are made of aluminum or aluminum alloy or plastic material.

[0018] Furthermore, a gasket is provided between the flange cover and the first planetary gear.

[0019] Furthermore, the eccentric shaft has an eccentric part in the middle, and the eccentric part is fitted with a third bearing.

[0020] Furthermore, the motor is a brushless motor or a brushed motor.

[0021] This utility model also provides an electric tool, comprising:

[0022] The body includes a plunger assembly;

[0023] The aforementioned drive device for power tools is mounted on the machine body, and the eccentric shaft corresponds to the plunger assembly.

[0024] In summary, the drive device and power tool provided by this utility model have the following technical effects:

[0025] 1. Five second planetary gears are installed on the second planetary carrier, which is directly connected to the eccentric shaft. Compared with the conventional planetary gear set, which generally uses three planetary gears, this significantly increases the number of support points for power transmission. This structure allows the load at the output end to be shared by the five planetary gears, effectively reducing the stress and wear on each second planetary gear. Thus, without adding complex structures or expensive materials, it greatly improves the service life and operational reliability of the reducer under high load conditions at extremely low cost.

[0026] 2. By setting a two-stage planetary transmission structure, the power output of the motor is transmitted through two reduction speeds, which significantly reduces the final output speed and greatly increases the output torque, meeting the needs of power tools for high-load operations. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0028] Figure 2 This is a schematic diagram of the exploded structure of this utility model;

[0029] Figure 3 This is a schematic diagram of the first cross-sectional structure of the present invention;

[0030] Figure 4 This is a schematic diagram of the second cross-sectional structure of the present invention.

[0031] Figure 5 This is an exploded structural diagram of the motor and reducer of this utility model;

[0032] Figure 6 This is an exploded structural diagram of the speed reducer of this utility model;

[0033] Figure 7 This is a schematic diagram of the eccentric shaft of this utility model;

[0034] The meanings of the reference numerals in the attached drawings are as follows: 1. Motor; 11. Output shaft; 12. Motor gear; 2. Reducer; 21. Gearbox housing; 211. Gearbox outer shell; 212. Flange cover; 213. First bearing mounting hole; 22. Internal gear ring; 23. First planetary carrier; 231. Sun gear; 24. First planetary gear; 25. Second planetary carrier; 251. Strip hole; 26. Second planetary gear; 3. End cover; 31. Second bearing mounting hole; 4. Eccentric shaft; 41. Flat part; 42. Eccentric part; 5. First bearing; 6. Second bearing; 7. Third bearing; 8. Gasket. Detailed Implementation

[0035] To better understand and implement this invention, the technical solutions in the embodiments of this invention will be clearly and completely described and discussed below with reference to the accompanying drawings. Obviously, what is described here is only a part of the examples of this invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the protection scope of this invention.

[0036] To facilitate understanding of the embodiments of this utility model, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. These embodiments do not constitute a limitation on the embodiments of this utility model.

[0037] In the description of this utility model, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0039] See Figures 1-7This utility model discloses a drive device for power tools, including a motor 1, a reducer 2, an end cover 3, and an eccentric shaft 4. The motor 1 has an output shaft 11 with a motor gear 12 mounted on it. The reducer 2 includes a gearbox housing 21 and an internal gear ring 22, a first planetary carrier 23, several first planetary gears 24, a second planetary carrier 25, and five second planetary gears 26 installed within the gearbox housing 21. The first planetary carrier 23 has a sun gear 231 facing away from the first planetary gears 24. All the first planetary gears 24 and all the... The second planetary gears 26 all mesh with the internal gear ring 22; the motor gear 12 meshes with all the first planetary gears 24, and the gear shafts of all the first planetary gears 24 are connected to the first planetary carrier 23; the sun gear 231 meshes with all the second planetary gears 26, and the gear shafts of all the second planetary gears 26 are connected to the second planetary carrier 25; the end cover 3 is located at the end of the gearbox housing 21 away from the motor 1; the eccentric shaft 4 is connected to the second planetary carrier 25 for transmission; and the eccentric shaft 4 is rotatably disposed in the plunger mounting cavity formed between the second planetary carrier 25 and the end cover 3.

[0040] Specifically, motor 1 is located at one end of the drive unit, and its interior has a rotatable output shaft 11. A motor gear 12 is fixedly mounted on the output shaft 11. This motor gear 12 serves as the power input end, used to transmit the power generated by motor 1 to reducer 2. Reducer 2 includes a gearbox housing 21, which integrates an internal gear ring 22, a first planetary carrier 23, several first planetary gears 24, a second planetary carrier 25, and five second planetary gears 26. The internal gear ring 22 is fixed to the inner wall of the gearbox housing 21, and its inner circumference has internal teeth for meshing with the first planetary gears 24 and second planetary gears 26. The first planetary carrier 23 is located at the front of reducer 2, and its side has several mounting holes for rotatably connecting the gear shafts of the multiple first planetary gears 24, so that all the first planetary gears 24 are rotatably connected to the first planetary carrier 23. Motor gear 12 meshes with all the first planetary gears 24 simultaneously to achieve power transmission. A sun gear 231 is located on the side of the first planetary carrier 23 facing away from the first planetary gears 24. When the first planetary gear 24 drives the first planetary carrier 23 to rotate, the sun gear 231 rotates synchronously with the first planetary carrier 23, thus realizing the purpose of the sun gear 231 as the input component of the second stage transmission. The second planetary carrier 25 is located behind the first planetary carrier 23 and has five mounting holes for rotatably connecting the gear shafts of the five second planetary gears 26, so that all the second planetary gears 26 are rotatably connected to the second planetary carrier 25. The sun gear 231 meshes with the five second planetary gears 26 simultaneously, forming the second stage planetary transmission. The external teeth of all the first planetary gears 24 and all the second planetary gears 26 mesh with the internal gear ring 22 simultaneously, forming a two-stage planetary gear transmission system. The end cover 3 is installed on the end of the gearbox housing 21 away from the motor 1 and is fixed by bolts or press-fitting. The eccentric shaft 4 serves as a power output component. One end of it is connected to the second planetary carrier 25 and rotates synchronously with the second planetary carrier 25. The other end extends into the plunger mounting cavity formed between the second planetary carrier 25 and the end cover 3. The eccentric shaft 4 is supported by the plunger mounting cavity formed by the second planetary carrier 25 and the end cover 3. It has a compact structure, high rigidity, and is conducive to improving output stability.

[0041] The working principle of the above structure:

[0042] After the motor 1 starts, the power is transmitted to the first planetary gear 24 through the motor gear 12 on the output shaft 11, which drives the first planetary carrier 23 to revolve around the internal gear ring 22. The sun gear 231 at the rear end of the first planetary carrier 23 rotates accordingly, driving the five second planetary gears 26 to revolve around the sun gear 231. The second planetary gears 26 drive the second planetary carrier 25 to rotate, and finally output the power after deceleration and torque increase through the eccentric shaft 4.

[0043] In conventional planetary reducers 2, the number of planetary gears is usually three to balance manufacturing cost and load-bearing capacity. However, the load is greatest on the second planetary carrier 25, which is directly connected to the output end, and the three planetary gears are prone to stress concentration, affecting service life. This solution uses five second planetary gears 26 on the second planetary carrier 25. Compared to conventional designs, with almost no increase in material and processing costs, the load at the output end is shared by the five second planetary gears 26, reducing the load distribution on each second planetary gear 26. This greatly alleviates problems such as tooth surface wear, gear shaft deformation, and bearing fatigue. Compared to increasing the material strength of the second planetary gears 26 or increasing the material strength of the second planetary carrier 25, simply adding two second planetary gears 26 significantly improves the overall service life and operational reliability of the reducer 2 at a very low cost, making it particularly suitable for high-load, long-term power tool applications.

[0044] Alternatively, the sun gear 231 can be integrally formed with the second planetary carrier 25, which reduces the number of separate sun gears 231 and their mounting structures, simplifies the assembly process, and improves the utilization of axial space.

[0045] See Figure 1-4 As shown, in some embodiments, in order to further reduce the torque load at the second planetary carrier 25, the motor gear 12 and the sun gear 231 are each provided with sixteen teeth, all the first planetary gears 24 and all the second planetary gears 26 are provided with fourteen teeth, and the internal gear ring 22 is provided with forty-four teeth.

[0046] Specifically, in existing products, the motor gear 12 and sun gear 231 each have seventeen teeth, all first planetary gears 24 and all second planetary gears 26 each have fourteen teeth, and the internal gear ring 22 has forty-six teeth. Calculations show that when the motor 1 rotates one revolution, the output at the second planetary carrier 25 is 0.137 revolutions. In this design, the motor gear 12 and sun gear 231 each have sixteen teeth, all first planetary gears 24 and all second planetary gears 26 each have fourteen teeth, and the internal gear ring 22 has forty-four teeth. Calculations show that when the motor 1 rotates one revolution, the output at the second planetary carrier 25 is 0.132 revolutions. Gear surface wear during gear transmission mainly originates from relative sliding during meshing. When the transmission ratio changes slightly, the angular velocity difference between the gears also changes accordingly. This solution optimizes the meshing trajectory and sliding coefficient between the planetary gears (second planetary gear 26) and the sun gear 231, and between the planetary gears (first planetary gear 24 and second planetary gear 26) and the internal gear ring 22 by reasonably matching the number of teeth (the motor gear 12 and the sun gear 231 each have sixteen teeth, all the first planetary gears 24 and the second planetary gear 26 each have fourteen teeth, and the internal gear ring 22 has forty-four teeth). This reduces the relative sliding speed between the tooth surfaces at the same input speed, thereby reducing tooth surface fatigue and frictional wear. In particular, in power tools that operate at high frequencies and continuously, the durability under long-term operation is significantly improved.

[0047] In testing, a power tool drive unit with the aforementioned number of teeth was applied to an electric hydraulic clamp. Compared to the previous product, which exhibited abnormal gear wear, deformation, and even tooth breakage after 25,000 hydraulic cycles, this solution has already met the requirement of over 100,000 cycles. No maintenance of the gearbox is required during the testing process. Therefore, this solution can meet the requirement of brushed motor 1 carbon brush depletion (approximately 46,000-60,000 cycles), and there is no significant reduction in gearbox function and performance after replacing motor 1.

[0048] See Figure 1-4 As shown, in some embodiments, five second planetary gears 26 are evenly distributed around the sun gear 231.

[0049] Specifically, the five second planetary gears 26 are evenly distributed around the sun gear 231. The multi-point meshing structure makes the radial force in the transmission process more balanced, effectively offsetting some of the dynamic load, significantly improving the smoothness of the transmission, and reducing vibration and noise during operation.

[0050] See Figure 5 As shown, in some embodiments, there are three first planetary gears 24.

[0051] Specifically, the three first planetary gears 24 can be evenly distributed along the circumference of the motor gear 12. Compared to the five second planetary gears 26, the first planetary gears 24 are farther from the eccentric shaft 4, and their torque resistance requirement is smaller. Therefore, it is not necessary to set multiple first planetary gears 24 to meet the transmission requirements. Furthermore, using three first planetary gears 24 allows for more free space within the gearbox housing 21, providing greater flow space for the lubricating grease filling the reducer 2. This reduces the resistance of the lubricating grease to the first planetary gears 24 during movement, thereby improving the overall efficiency of the transmission system and reducing the temperature rise caused by useless power loss.

[0052] See Figure 1-3 and Figure 7 As shown, in some embodiments, the second planetary carrier 25 is provided with a strip hole 251, and the eccentric shaft 4 is provided with a flat part 41 at one end facing the second planetary carrier 25. The flat part 41 of the eccentric shaft 4 is installed in the strip hole 251.

[0053] Specifically, the second planetary carrier 25 serves as the output component of the secondary planetary transmission mechanism. The second planetary carrier 25 is provided with a strip-shaped hole 251, and one end of the eccentric shaft 4 is machined with a matching flat part 41. Its size is adapted to the strip-shaped hole 251, allowing the flat part 41 to be inserted into the strip-shaped hole 251 in a sliding fit manner.

[0054] When the drive unit is working, the second planetary carrier 25 rotates in conjunction with the meshing transmission of the five second planetary gears 26. The slotted hole 251 on the carrier rotates synchronously. Since the flat portion 41 of the eccentric shaft 4 is fixed in this slotted hole 251, the second planetary carrier 25 drives the eccentric shaft 4 to rotate together through surface contact torque transmission, thus achieving power output. This connection method is a keyless flat-groove transmission connection, avoiding the complex machining and assembly requirements of traditional key or spline structures, simplifying the structure and reducing costs.

[0055] See Figure 1-3 and Figure 6 As shown, in some embodiments, the gearbox housing 21 includes a gearbox outer shell 211 with an opening at one end and a first bearing mounting hole 213 at the other end, and a flange cover 212 disposed at the opening. The flange cover 212 is fixedly connected to the end face of the motor 1. One end of the eccentric shaft 4 is sleeved with a first bearing 5, and the eccentric shaft 4 is rotatably disposed on the first bearing mounting hole 213 through the first bearing 5. The other end of the eccentric shaft 4 is sleeved with a second bearing 6, and the eccentric shaft 4 is rotatably disposed on the end cover 3 through the second bearing 6.

[0056] Specifically, the gearbox housing 211 has an overall cylindrical structure, with one end near the motor 1 being open, while the other end has an integrally formed first bearing mounting hole 213 for mounting a bearing. A flange cover 212 covers this open end and is connected and fixed to the gearbox housing 211 by bolts or clips. The end face of the flange cover 212 is flush with the end face of the motor and locked with screws, achieving a rigid connection between the motor 1 and the reducer 2. The two ends of the eccentric shaft 4 are rotatably supported by a first bearing 5 and a second bearing 6, respectively. Specifically, one end of the eccentric shaft 4 is fitted with the first bearing 5, which is installed in the first bearing mounting hole 213 at the end of the gearbox housing 211; the other end of the eccentric shaft 4 is fitted with the second bearing 6, which is mounted on the end cover 3 and supported and positioned by the end cover 3. The eccentric shaft 4, supported by the first bearing 5 and the second bearing 6, forms a stable rotating structure with fixed ends, capable of withstanding the large radial force and axial impact load generated during the operation of the power tool.

[0057] See Figure 2 Therefore, in some embodiments, the end cap 3 is provided with a second bearing mounting hole 31, and the second bearing 6 is assembled in the second bearing mounting hole 31.

[0058] Specifically, the end cover 3 is installed on the end of the gearbox housing 211 away from the motor 1, and is fixedly connected to the gearbox housing 211 by means of threaded connection, bolt fixing or riveting. The end cover 3 is provided with a through second bearing mounting hole 31, the size of which matches the outer diameter of the selected second bearing 6, to ensure that the second bearing 6 can be firmly embedded and accurately positioned.

[0059] See Figure 1-3 As shown, in some embodiments, the gearbox housing 211, and / or the flange cover 212, and / or the end cover 3 are made of aluminum or aluminum alloy or plastic material.

[0060] Specifically, in traditional power tool drive units, to ensure structural strength, the reducer housing 2, flange cover 212, and end cover 3 are typically made of metal materials such as cast iron or carbon steel. While these materials possess high mechanical strength, their high density results in a heavy overall drive unit, which can easily cause operator fatigue, especially during prolonged handheld operation, severely impacting user comfort and operational precision. Using aluminum, aluminum alloy, or plastic materials for the gearbox housing 211, flange cover 212, and end cover 3 reduces weight and improves operator comfort.

[0061] See Figure 2 As shown, in some embodiments, a gasket 8 is provided between the flange cover 212 and the first planetary gear 24.

[0062] Specifically, the gasket 8 is disposed between the flange cover 212 and the first planetary gear 24. When the flange cover 212 is fastened to the gearbox housing 211 by bolts and connected to the end face of the motor 1, the gasket 8 is axially compressed to form a stable support interface for supporting the first planetary gear 24.

[0063] See Figure 2 , Figure 3 and Figure 7 As shown, in some embodiments, the eccentric shaft 4 has an eccentric part 42 in the middle, and the eccentric part 42 is fitted with a third bearing 7.

[0064] Specifically, the eccentric shaft 4 is a stepped shaft, and the eccentric part 42 is a section with a larger diameter located in the middle region of the eccentric shaft 4, whose geometric center does not coincide with the rotation center. When the eccentric shaft 4 rotates around its two end support points, the eccentric part 42 will generate periodic radial displacement motion. A third bearing 7 is sleeved on the outer circumferential surface of the eccentric part 42, thereby converting the traditional sliding friction between the eccentric part 42 and the plunger into rolling friction when the third bearing 7 contacts the plunger, thus improving the service life of the plunger.

[0065] In some embodiments, motor 1 is a brushless motor or a brushed motor.

[0066] Specifically, this drive unit is not dependent on a specific type of motor and can be flexibly equipped with either a brushed motor or a brushless motor according to different application scenarios and cost requirements. The same reducer can be used in multiple product series.

[0067] This utility model also provides an electric tool, including a body and the above-mentioned drive device for electric tools. The body includes a plunger assembly, the drive device is disposed on the body, and the eccentric shaft 4 corresponds to the plunger assembly so that when the eccentric shaft 4 moves, the plunger assembly can bring the oil in the oil bag into the piston chamber through the oil inlet channel.

[0068] Specifically, the power tool includes a body, an oil bag, and the aforementioned power tool drive unit. The body is provided with a piston chamber and an oil inlet channel connecting the piston chamber and the oil bag. A plunger assembly is provided on the oil inlet channel. The drive unit is located on the body. An eccentric shaft 4 corresponds to the plunger assembly so that when the eccentric shaft 4 moves, the plunger assembly can bring the oil in the oil bag into the piston chamber through the oil inlet channel.

[0069] This power tool can be freely adapted to different functional working heads, and by adopting the aforementioned drive device, the service life of the power tool can be greatly improved.

[0070] The technical means disclosed in this utility model are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications are also considered within the scope of protection of this utility model.

Claims

1. A drive device for power tools, characterized in that, include: The motor (1) has an output shaft (11) and a motor gear (12) is provided on the output shaft (11); The reducer (2) includes a gearbox housing (21) and an internal gear ring (22), a first planet carrier (23), a plurality of first planet gears (24), a second planet carrier (25), and five second planet gears (26) installed in the gearbox housing (21). The first planet carrier (23) has a sun gear (231) facing away from the first planet gears (24). All the first planet gears (24) and all the second planet gears (26) mesh with the internal gear ring (22). The motor gear (12) meshes with all the first planet gears (24). The gear shafts of all the first planet gears (24) are connected to the first planet carrier (23). The sun gear (231) meshes with all the second planet gears (26). The gear shafts of all the second planet gears (26) are connected to the second planet carrier (25). End cap (3), the end cap (3) is located at the end of the gearbox housing (21) away from the motor (1); An eccentric shaft (4) is connected to the second planetary carrier (25) for transmission. The eccentric shaft (4) is rotatably disposed in the plunger mounting cavity formed between the second planetary carrier (25) and the end cap (3).

2. The drive device for power tools according to claim 1, characterized in that, The motor gear (12) and the sun gear (231) each have sixteen teeth, all the first planetary gears (24) and all the second planetary gears (26) each have fourteen teeth, and the internal gear ring (22) has forty-four teeth.

3. The drive device for power tools according to claim 1, characterized in that, Five second planetary gears (26) are evenly distributed around the sun gear (231).

4. A drive device for power tools according to claim 1, characterized in that, The first planetary gear (24) consists of three.

5. A drive device for power tools according to claim 1, characterized in that, The second planetary carrier (25) is provided with a strip hole (251), and the eccentric shaft (4) is provided with a flat part (41) at one end facing the second planetary carrier (25), and the flat part (41) of the eccentric shaft (4) is installed in the strip hole (251).

6. A drive device for power tools according to claim 1, characterized in that, The gearbox housing (21) includes a gearbox outer shell (211) with an opening at one end and a first bearing mounting hole (213) at the other end, and a flange cover (212) provided at the opening. The flange cover (212) is fixedly connected to the end face of the motor (1). One end of the eccentric shaft (4) is fitted with a first bearing (5), and the eccentric shaft (4) is rotatably mounted on the first bearing mounting hole (213) through the first bearing (5). The other end of the eccentric shaft (4) is fitted with a second bearing (6), and the eccentric shaft (4) is rotatably mounted on the end cover (3) through the second bearing (6).

7. A drive device for power tools according to claim 6, characterized in that, The gearbox housing (211), and / or the flange cover (212), and / or the end cover (3) are made of aluminum or aluminum alloy or plastic material.

8. A drive device for power tools according to claim 6, characterized in that, A gasket (8) is provided between the flange cover (212) and the first planetary gear (24).

9. A drive device for power tools according to claim 1, characterized in that, The motor (1) is a brushless motor or a brushed motor.

10. A power tool, characterized in that, include: The body includes a plunger assembly; The power tool drive device according to any one of claims 1-9, wherein the drive device is disposed on the machine body, and the eccentric shaft (4) corresponds to the plunger assembly.

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