An electric impact tool

Abstract

The electric impact tool comprises a containing part with a containing space inside, a speed reduction transmission part arranged in the containing part, the speed reduction transmission part comprising an inner gear ring and a motor gear, a first stage planetary gear, a second stage planetary gear and a coupling gear arranged in the inner gear ring and engaged, and an impact working part arranged in the containing part, the impact working part comprising a camshaft, a striking block, a working shaft and an impact spring, the camshaft being arranged between the speed reduction transmission part and the working shaft, the striking block being arranged around the camshaft, and the impact spring pressing the striking block towards the working shaft. The application adopts a two-stage NGW planetary gear train or a one-stage NW planetary gear train speed reduction structure, has a large speed reduction ratio, can increase the impact torque under the condition that the output rotation speed of the impact wrench is unchanged, can avoid frequent protection of the battery pack due to excessively high temperature rise, and can improve the working efficiency.

Description

Technical Field

[0001] This invention relates to the field of power tool technology, and in particular to an electric impact tool. Background Technology

[0002] Most electric impact wrench gearboxes on the market consist of a single-stage planetary gear reduction mechanism and an impact mechanism, with reduction ratios typically between 8:1 and 12:1. For high-torque rechargeable lithium-ion impact wrenches with impact torque exceeding 500 Nm, the average operating current is relatively high, generally between 45A and 70A. This requires the lithium-ion battery pack to withstand high currents, usually achieved by using multiple 18650 lithium-ion battery packs in parallel or 21700 lithium-ion battery packs capable of handling even higher currents, which increases the cost of the main unit. Furthermore, due to the over-temperature protection characteristics of lithium-ion batteries, the higher the operating current, the faster the temperature rises in the lithium-ion battery pack and the main unit controller. This makes the main unit more prone to frequent over-temperature protection shutdowns during operation, negatively impacting the actual user experience of the lithium-ion impact wrench.

[0003] In addition, high-torque electric impact wrenches are generally large and not compact in structure due to their large impact torque. The core component of the impact mechanism, the camshaft, is made from precision cast steel blanks or cold-forged and cold-extruded blanks, which are then machined. The processing technology is complex and the manufacturing cost is high.

[0004] An impact wrench disclosed in Patent Document 1 includes: a housing; a motor connected to the housing, the motor having an output shaft; an anvil assembly; a power transmission mechanism drivably connecting the output shaft to the anvil assembly, the power transmission mechanism including a sun gear, a first planetary gear, a second planetary gear, a planetary carrier, an input spindle, and a bearing support plate with annular internal teeth, the sun gear being driven by the output shaft, the first and second planetary gears being fixedly connected to each other and rotatably mounted on the planetary carrier; an input spindle bearing sleeved on the planetary carrier and housed within the bearing support plate, an annular rear cover provided between the motor and the power transmission mechanism, a motor bearing for supporting the output shaft being partially received within the annular rear cover.

[0005] And an impact tool disclosed in Patent Document 2 includes: a housing; an electric motor supported within the housing and having a motor shaft; and a drive assembly configured to convert a continuous rotary input from the motor shaft into a continuous rotary impact acting on a workpiece. The drive assembly includes a camshaft having a front and a rear portion. A gear assembly is coupled between the motor shaft and the drive assembly, the gear assembly including a ring gear and a plurality of planetary gears meshing with the ring gear, the ring gear being rotatably and radially fixed relative to the housing. Each of the plurality of planetary gears is coupled to the rear portion of the camshaft, and the line of action of the radial load applied to the housing by the rear portion of the camshaft passes through one of the plurality of planetary gears and the ring gear.

[0006] The problem with Patent Document 1 is that the rear end of the camshaft is supported by a bearing, resulting in a non-compact structure. Furthermore, the processing technology is complex, the manufacturing cost is high, and the reduction ratio of the gearbox is limited.

[0007] The problem with Patent Document 2 is that the gearbox is a single-stage planetary gear reduction mechanism, which limits the reduction ratio. Furthermore, the radial force of the camshaft is transmitted to the housing by the planetary gear through the ring gear. The planetary gear, ring gear, and planetary gear locating pin are prone to wear, and the camshaft of this structure is too expensive to manufacture.

[0008] Therefore, while keeping the output speed of the impact wrench constant, the problems that need to be solved are how to reduce the average operating current of the lithium battery impact wrench, improve working efficiency and enhance the user experience, simplify the processing technology of parts, and reduce the manufacturing cost of the product.

[0009] Patent document 1 CN212601568U.

[0010] Patent document 2 CN216398138U. Summary of the Invention

[0011] To overcome the shortcomings of existing technologies, this invention provides an electric impact tool that can increase impact torque while reducing average operating current, while keeping the output speed of the impact wrench constant.

[0012] The present invention solves the technical problem by adopting the following technical solution: an electric impact tool, comprising:

[0013] The compartment has internal storage space.

[0014] A speed reduction transmission unit is disposed within a receiving portion. The speed reduction transmission unit includes an internal gear ring and a motor gear, a first-stage planetary gear, a second-stage planetary gear, and a connecting gear that are meshed within the internal gear ring.

[0015] An impact working part is disposed within a receiving part. The impact working part includes a camshaft, an impact block, a working shaft, and an impact spring. The camshaft is connected between the reduction transmission part and the working shaft. The impact block is disposed around the camshaft, and the impact spring presses the impact block toward the working shaft.

[0016] The camshaft has a connecting disc on the side facing the reduction gear, and an internal gear ring is placed in the connecting disc for mounting multiple second-stage planetary gears. The first-stage planetary gears and the second-stage planetary gears are respectively arranged on opposite sides of the connecting gear, and the multiple first-stage planetary gears mesh with the motor gears for transmission.

[0017] In several embodiments, the connecting disc body has a plurality of protruding mounting posts, and the second-stage planetary gear is mounted on the mounting posts.

[0018] In several embodiments, the connecting gear includes a disk carrier, a central gear, and a plurality of protruding pillars. The protruding pillars and the central gear are disposed on opposite sides of the disk carrier. The central gear meshes with a second-stage planetary gear for transmission. The protruding pillars are used to mount a first-stage planetary gear.

[0019] In several embodiments, one side of the internal gear ring extends outward along its axial direction to form an extended ring body. The inner diameter of the extended ring body has a diameter difference with the inner diameter of the internal gear ring, thereby forming a stepped positioning end. The connecting disc body is placed inside the extended ring body and corresponds to the positioning end.

[0020] In several embodiments, a gasket is fitted between the connecting disc and the positioning end.

[0021] In several embodiments, the receiving portion is composed of a head housing and a gearbox body that are interconnected and internally communicated with each other. The head housing is used to house the impact working part, and the gearbox body is used to house the reduction transmission part. The reduction transmission part provides a reduction ratio between 13:1 and 40:1.

[0022] And another type of electric impact tool includes: a receiving part having a receiving space inside; a speed reduction transmission part disposed in the receiving part, the speed reduction transmission part including an internal gear ring and a motor gear, a first-stage planetary gear and a second-stage planetary gear disposed in the internal gear ring;

[0023] An impact working part is disposed within a receiving part. The impact working part includes a camshaft, an impact block, a working shaft, and an impact spring. The camshaft is connected between the reduction transmission part and the working shaft. The impact block is disposed around the camshaft, and the impact spring presses the impact block toward the working shaft.

[0024] The camshaft has a connecting disc on the side facing the reduction gear, and an internal gear ring is placed in the connecting disc. The first-stage planetary gear and the second-stage planetary gear are fixedly connected and mounted on the connecting disc. The first-stage planetary gear meshes with the motor gear for transmission.

[0025] In several embodiments, one side of the internal gear ring extends outward along its axial direction to form an extended ring body. The inner diameter of the extended ring body has a diameter difference with the inner diameter of the internal gear ring, thereby forming a stepped positioning end. The connecting disc body is placed inside the extended ring body and corresponds to the positioning end.

[0026] In several embodiments, a gasket is fitted between the connecting disc and the positioning end.

[0027] In several embodiments, the receiving portion is composed of a head housing and a gearbox body that are interconnected and internally communicated with each other. The head housing is used to house the impact working part, and the gearbox body is used to house the reduction transmission part. The reduction transmission part provides a reduction ratio between 13:1 and 40:1.

[0028] The present invention has the following beneficial effects:

[0029] (1) The speed reduction transmission unit adopts a two-stage NGW planetary gear system or a one-stage NW planetary gear system with a large reduction ratio. While keeping the output speed of the impact wrench constant, the output torque of the motor is increased through the gearbox, and the average working current is reduced. This reduces the temperature rise of the lithium battery pack and the main controller of the lithium battery impact wrench during operation, avoids the impact wrench from frequently going into protection due to excessive temperature rise, and improves working efficiency.

[0030] (2) The connecting disc of the camshaft is positioned radially and axially by using the step on the end face of the internal gear ring, which reduces the radial and axial forces from the camshaft on the planetary gear, the teeth of the internal gear ring and the mounting column, thereby reducing the wear of the gears and the mounting column and extending the service life of the gearbox.

[0031] (3) The gearbox has a compact structure, is easy to install, and key components such as the camshaft are easy to process, resulting in low manufacturing costs. Attached Figure Description

[0032] The accompanying drawings described herein are for illustrative purposes only and do not represent all possible implementations, nor should they be considered as limiting the scope of the invention.

[0033] Figure 1 A schematic cross-sectional view of the complete assembly of Embodiment 1 is shown;

[0034] Figure 2 schematically shown Figure 1 A locally magnified structure;

[0035] Figure 3 schematically shown Figure 2 The explosive structure;

[0036] Figure 4 schematically shown Figure 2 The mounting structure of the intermediate speed reduction transmission unit;

[0037] Figure 5 schematically shown Figure 2 Separation structure between the internal gear ring and the camshaft;

[0038] Figure 6 A schematic cross-sectional view of the complete assembly of Embodiment 2 is shown.

[0039] Figure 7 schematically shown Figure 6 A locally magnified structure;

[0040] Figure 8 schematically shown Figure 7 The explosive structure;

[0041] Figure 9 schematically shown Figure 6 The mounting structure of the intermediate speed reduction transmission unit;

[0042] Figure 10 schematically shown Figure 6 Separate structure of internal gear ring and camshaft. Detailed Implementation

[0043] The embodiments of the present invention will be described in detail below. In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0044] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0045] The terminology used herein is intended to explain the embodiments and is not intended to limit and / or restrict the invention.

[0046] For example, expressions such as "in a certain direction," "along a certain direction," and "relative" indicate relative or absolute configuration. They not only indicate such a configuration in a strict sense, but also indicate a state of relative displacement with tolerances or angles or distances that can achieve the same level of functionality.

[0047] Example 1

[0048] like Figures 1-5 The structure of the electric impact tool in this embodiment mainly consists of a receiving part, a motor 12, a speed reduction transmission part, and an impact working part disposed inside the receiving part. The speed reduction transmission part increases the output torque of the motor and transmits it to the impact working part to apply force.

[0049] Here, the housing is mainly composed of a head housing 1, a gearbox 2, a rear housing 13, and a handle housing 15. The head housing 1, the gearbox 2, and the rear housing 13 are connected in sequence and internally connected. The motor 12 is installed in the rear housing 13. The three are arranged coaxially. The handle housing 15 is connected to the lower part of the three, and a button 14 is provided on it to control the movement of the motor 12.

[0050] Specifically, the reduction transmission unit is located inside the gearbox 2 and adopts a two-stage NGW planetary gear system structure. The reduction ratio provided by the reduction transmission unit is between 13:1 and 40:1. It includes an internal gear ring 7 and a motor gear 3, a first-stage planetary gear 4, a second-stage planetary gear 5 and a connecting gear 6 that are configured and meshed inside the internal gear ring 7. The motor gear 3 is connected to the output shaft of the motor 12.

[0051] The connecting gear 6 includes a disk carrier, a central gear, and multiple convex pillars, forming a sun gear structure. The convex pillars and the central gear are located on opposite sides of the disk carrier, and the central gear meshes with the second-stage planetary gear 5 for transmission. The corresponding convex pillars are used to install the first-stage planetary gear 4. Generally, three convex pillars are evenly distributed at 120° to install three first-stage planetary gears 4.

[0052] Furthermore, the impact working part is located in the head housing 1, mainly including a camshaft 8, an impact block 9, a working shaft 10 and an impact spring 11. The camshaft 8 is connected between the reduction transmission part and the working shaft 10. The impact block 9 is arranged around the camshaft 8, and the impact spring 11 presses the impact block 9 toward the working shaft 10. This is a conventional impact structure in the field, and no further limitations are made here.

[0053] The camshaft 8 has a connecting disc 8.1 on the side facing the reduction gear transmission unit. The two are arranged on the same axis. The connecting disc 8.1 can be a flange structure. The connecting disc 8.1 is fitted with an internal gear ring 7 and is used to install three second-stage planetary gears 5. The first-stage planetary gears 4 and the second-stage planetary gears 5 are respectively arranged on opposite sides of the connecting gear 6. The three first-stage planetary gears 4 mesh with the motor gear 3 for transmission.

[0054] One side of the internal gear ring 7 extends outward along its axial direction to form an extended ring body. The inner diameter of the extended ring body has a diameter difference with the inner diameter of the internal gear ring 7, thus forming a stepped positioning end 7.1. The connecting disc body 8.1 is inserted into the extended ring body and corresponds to the positioning end 7.1. Thus, the radial and axial forces of the camshaft 8 can be borne by the connecting disc body 8.1 and the connection position between the connecting disc body 8.1 and the internal gear ring 7. At the same time, a gasket 16 can be fitted between the connecting disc body 8.1 and the positioning end 7.1 to reduce the friction between the two.

[0055] Thus, the three first-stage planetary gears 4 and the three second-stage planetary gears 5 are separate and installed on opposite sides of the connecting gear 6. The three first-stage planetary gears 4 mesh with the motor gear 3 that extends into the center of the three. The transmission cooperation between the first-stage planetary gears 4, the three second-stage planetary gears 5, the internal gear ring 7 and the connecting gear 6 realizes the transmission structure of the two-stage NGW planetary gear system.

[0056] Example 2

[0057] like Figure 6-10 The structure of the electric impact tool in Embodiment 2 is also composed of a receiving part and a motor 32, a speed reduction transmission part and an impact working part disposed inside the receiving part. The speed reduction transmission part increases the output torque of the motor and transmits it to the impact working part to apply force.

[0058] The housing is also composed of a head housing 21, a gearbox 22, a rear housing 33, and a handle housing 35. The head housing 21, gearbox 22, and rear housing 33 are connected in sequence and internally connected. The motor 32 is installed in the rear housing 33. The three are arranged coaxially. The handle housing 35 is connected to the lower part of the three, and a button 34 is provided on it to control the movement of the motor 32.

[0059] The reduction transmission unit is located inside the gearbox 22 and adopts a single-stage NW planetary gear system structure, including an internal gear ring 27, a motor gear 23 disposed within the internal gear ring 27, three first-stage planetary gears 24, and three second-stage planetary gears 25. The internal gear ring 27 is rotatably and radially mounted in the gearbox 22. Here, the first-stage planetary gears 24 and the second-stage planetary gears 25 are fixedly connected to form a double gear structure, and the transmission is achieved by the meshing of the first-stage planetary gears 24 and the motor gears 23.

[0060] The impact working part is located inside the head housing 21 and mainly includes a camshaft 28, an impact block 29, a working shaft 30, and an impact spring 31. The camshaft 28 is connected between the reduction transmission part and the working shaft 30. The impact block 29 is arranged around the camshaft 28, and the impact spring 31 presses the impact block 29 toward the working shaft 30. This is also a conventional structure in the field and will not be further limited here.

[0061] Similar to Embodiment 1, a flange-structured connecting disc 28.1 is coaxially arranged on the side of the camshaft 28 facing the reduction gear section. An internal gear ring 27 is placed in the connecting disc 28.1. The first-stage planetary gear 24 and the second-stage planetary gear 25 are fixedly connected and mounted on the connecting disc 28.1. The first-stage planetary gear 24 meshes with the motor gear 23 for transmission.

[0062] Correspondingly, an extension ring extends outward along its axial direction on one side of the internal gear ring 27 to form an extension ring body. The inner diameter of the extension ring body has a diameter difference with the inner diameter of the internal gear ring 27, thereby forming a stepped positioning end 27.1. The connecting disc body 28.1 is inserted into the extension ring body and corresponds to the positioning end 27.1. Similarly, a gasket 36 can be fitted between the connecting disc body 28.1 and the positioning end 27.1 to reduce friction.

[0063] Therefore, the reduction transmission unit in this invention adopts a reduction structure of a two-stage NGW planetary gear system or a single-stage NW planetary gear system, with a large reduction ratio that can meet the requirements of a reduction ratio between 13:1 and 40:1. While keeping the output speed of the impact wrench constant, the output torque of the motor is increased through the gearbox, while the average operating current is reduced. This reduces the temperature rise of the lithium battery pack and the main controller of the lithium battery impact wrench during operation, avoids frequent protection due to excessive temperature rise of the impact wrench, and improves work efficiency.

[0064] By using a specific connection structure between the camshaft and the internal gear ring, the rear end of the camshaft can be freed from traditional bearing or bushing support, making the impact mechanism structure more compact. At the same time, it simplifies the camshaft machining process and saves manufacturing costs.

[0065] The examples, embodiments, and particular forms of the invention illustrated have been shown and described in detail in the accompanying drawings and foregoing description, and should also be considered illustrative rather than restrictive. The description of a particular feature in one embodiment does not imply that those particular features must be limited to that one embodiment. Features of one embodiment can be used in combination with features of other embodiments, as will be understood by those skilled in the art, whether or not explicitly stated. Exemplary embodiments have been shown and described, and all variations and modifications fall within the spirit of the invention and are intended to be protected.

Claims

1. An electric impact tool, characterized in that, include: The compartment has internal storage space. A speed reduction transmission unit is disposed within a receiving portion. The speed reduction transmission unit includes an internal gear ring and a motor gear, a first-stage planetary gear, a second-stage planetary gear, and a connecting gear that are meshed within the internal gear ring. An impact working part is disposed within a receiving part. The impact working part includes a camshaft, an impact block, a working shaft, and an impact spring. The camshaft is connected between the reduction transmission part and the working shaft. The impact block is disposed around the camshaft, and the impact spring presses the impact block toward the working shaft. The camshaft has a connecting disc on the side facing the reduction gear, the connecting disc is fitted with an internal gear ring and is used to install multiple second-stage planetary gears, the first-stage planetary gears and the second-stage planetary gears are respectively arranged on opposite sides of the connecting gear, and the multiple first-stage planetary gears mesh with the motor gears for transmission. One side of the internal gear ring extends outward along its axial direction to form an extended ring body. The inner diameter of the extended ring body has a diameter difference with the inner diameter of the internal gear ring, thereby forming a stepped positioning end. The connecting disc body is placed inside the extended ring body and corresponds to the positioning end.

2. The electric impact tool according to claim 1, characterized in that, The connecting disc body has multiple protruding mounting posts, and the second-stage planetary gear is mounted on the mounting posts.

3. The electric impact tool according to claim 2, characterized in that, The connecting gear includes a disk carrier, a central gear, and multiple convex pillars. The convex pillars and the central gear are disposed on opposite sides of the disk carrier. The central gear meshes with a second-stage planetary gear for transmission. The convex pillars are used to mount the first-stage planetary gear.

4. An electric impact tool according to claim 3, characterized in that, A gasket is fitted between the connecting disc and the positioning end.

5. An electric impact tool according to claim 4, characterized in that, The receiving part is composed of a head housing and a gearbox body that are connected to each other and internally communicate with each other. The head housing is used to accommodate the impact working part, and the gearbox body is used to accommodate the reduction transmission part. The reduction transmission part provides a reduction ratio between 13:1 and 40:

1.

6. An electric impact tool, characterized in that, include: The compartment has internal storage space. A speed reduction transmission unit is disposed within a receiving portion. The speed reduction transmission unit includes an internal gear ring and a motor gear, a first-stage planetary gear, and a second-stage planetary gear disposed within the internal gear ring. An impact working part is disposed within a receiving part. The impact working part includes a camshaft, an impact block, a working shaft, and an impact spring. The camshaft is connected between the reduction transmission part and the working shaft. The impact block is disposed around the camshaft, and the impact spring presses the impact block toward the working shaft. The camshaft has a connecting disc on the side facing the reduction gear, an internal gear ring is placed in the connecting disc, the first stage planetary gear and the second stage planetary gear are fixedly connected and mounted on the connecting disc, and the first stage planetary gear meshes with the motor gear for transmission. One side of the internal gear ring extends outward along its axial direction to form an extended ring body. The inner diameter of the extended ring body has a diameter difference with the inner diameter of the internal gear ring, thereby forming a stepped positioning end. The connecting disc body is placed inside the extended ring body and corresponds to the positioning end.

7. An electric impact tool according to claim 6, characterized in that, A gasket is fitted between the connecting disc and the positioning end.

8. An electric impact tool according to claim 7, characterized in that, The receiving part is composed of a head housing and a gearbox body that are connected to each other and internally communicate with each other. The head housing is used to accommodate the impact working part, and the gearbox body is used to accommodate the reduction transmission part. The reduction transmission part provides a reduction ratio between 13:1 and 40:1.

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