Power tool

Abstract

The present invention discloses an electric tool, comprising an output shaft, an impact mechanism and a transmission mechanism, wherein the transmission mechanism is installed in a linkage manner between the output shaft and the impact mechanism, and is used to transmit the torque generated by the impact mechanism to the output shaft, and the transmission mechanism comprises: a connecting member, which is driven by the impact mechanism and can rotate around its own axis; a reduction gear set, which is installed in a linkage manner between the output shaft and the connecting member, the reduction gear set is driven by the connecting member, and the reduction gear can drive the output shaft to rotate around its own axis; wherein the rotational speed of the connecting member is greater than the rotational speed of the output shaft.

Description

Technical Field

[0001] The present invention relates to an electric tool, in particular to an electric tool with an impact structure. Background Art

[0002] Impact wrenches, among power tools, utilize an impact mechanism to continuously impact the wrench head (output shaft) to generate a tightening torque. The torque output of an impact wrench depends on the speed of the impact mechanism and the weight and size of the impact block within the mechanism. Adjustment of the impact mechanism's speed is limited by the motor's speed, and faster speeds increase wear on the components within the mechanism. Given the limited speed adjustment of the impact mechanism, increasing the torque of the impact wrench requires a larger impact block. A larger impact block also increases the size of the wrench. Developing an impact wrench that delivers high torque while maintaining a compact footprint is a pressing technical challenge.

[0003] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0004] An object of the present invention is to provide an electric tool capable of increasing the torque of an output shaft in the electric tool.

[0005] To achieve the above-mentioned object, an embodiment of the present invention provides an electric tool, comprising an output shaft, an impact mechanism, and a transmission mechanism, wherein the transmission mechanism is interlockingly installed between the output shaft and the impact mechanism and is used to transmit the torque generated by the impact mechanism to the output shaft, and the transmission mechanism comprises:

[0006] A connecting member, driven by the impact mechanism, capable of rotating around its own axis;

[0007] a reduction gear set, which is installed in linkage between the output shaft and the connecting member, the reduction gear set is driven by the connecting member, and the reduction gear can drive the output shaft to rotate around its own axis;

[0008] Wherein, the rotation speed of the connecting member is greater than the rotation speed of the output shaft.

[0009] In one or more embodiments of the present invention, a ratio of the rotational speed of the connecting member to the rotational speed of the output shaft is greater than or equal to 2.

[0010] In one or more embodiments of the present invention, a ratio of the rotational speed of the connecting member to the rotational speed of the output shaft is 2-4.

[0011] In one or more embodiments of the present invention, the reduction gear set includes an input gear and an output member in transmission connection, the output member is connected to the output shaft, and the input gear is connected to the connecting member.

[0012] In one or more embodiments of the present invention, the reduction gear set is a first planetary gear system, which includes the input gear, a plurality of first planetary gears surrounding and meshing with the input gear, a first inner ring gear meshing with the plurality of first planetary gears, and the output member carrying the plurality of first planetary gears.

[0013] In one or more embodiments of the present invention, the reduction gear set is a fixed-axis gear system, the output member is a gear, the fixed-axis gear system includes an input gear, a plurality of fixed gears surrounding and meshing with the input gear, the output member meshing with the plurality of fixed gears, and a gear carrier carrying the plurality of fixed gears, the fixed gear includes a first gear portion and a second gear portion coaxially arranged, the first gear portion meshing with the input gear, and the second gear portion meshing with the output member.

[0014] In one or more embodiments of the present invention, the output member includes an inner gear ring portion and a connecting portion, the connecting portion has a stop hole, the output shaft is plugged into the stop hole to form a stop structure, and the inner gear ring portion is engaged with the input gear.

[0015] In one or more embodiments of the present invention, the input gear is integrally connected to the connecting member.

[0016] In one or more embodiments of the present invention, the impact mechanism has a driving shaft, and the end of the connecting member facing the impact mechanism has a first connecting hole, and the driving shaft is plugged into the first connecting hole.

[0017] In one or more embodiments of the present invention, a ball is mounted on the axial inner wall of the first connecting hole and the driving shaft by clamping.

[0018] Compared to the prior art, the power tool according to the embodiments of the present invention increases the torque of the output shaft by adding a transmission mechanism between the impact mechanism and the output shaft. Specifically, the impact mechanism impacts the connecting member, causing the connecting member to rotate. The connecting member is then connected to the output shaft via a reduction gear set. By utilizing the principle of torque reduction and torque amplification of the reduction gear set, the torque generated by the impact mechanism impacting the connecting member is transmitted to the output shaft after being amplified by the reduction gear set, thereby increasing the torque of the output shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of a power tool according to an embodiment of the present invention;

[0020] Figure 2 is a cross-sectional schematic diagram of an electric tool according to an embodiment of the present invention;

[0021] Figure 3 is an exploded view of some parts of a power tool according to one embodiment of the present invention;

[0022] Figure 4 is an exploded view of an output shaft, an impact mechanism, and a transmission mechanism according to one embodiment of the present invention;

[0023] Figure 5 is an exploded view of an output shaft, an impact mechanism, and a transmission mechanism according to another embodiment of the present invention;

[0024] Figure 6 is a partial cross-sectional schematic diagram of an electric tool according to another embodiment of the present invention;

[0025] Figure 7 is an exploded view of an output shaft, an impact mechanism, and a transmission mechanism according to one embodiment of the present invention;

[0026] Figure 8 FIG. 1 is a partial cross-sectional schematic diagram of an electric tool according to an embodiment of the present invention.

[0027] Description of main reference numerals:

[0028] 1. Output shaft; 11. Stopper; 111. First stopper surface; 2. Impact mechanism; 21. Drive shaft; 3. Transmission mechanism; 31. Connector; 311. First connecting hole; 312. Protrusion; 32. Reduction gear set; 321. Input gear; 322. Output member; 3221. Internal gear ring; 3222. Connector; 3223. Stopper hole; 32231. Second stopper surface; 323. First planetary gear; 324. First internal gear ring; 325. Fixed gear; 3251. First gear Wheel part; 3252, second gear part; 326, gear rack; 3261, fixing frame; 32611, second connecting hole; 3262, end plate; 32621, third connecting hole; 3263, fixing shaft; 327, positioning plate; 3271, fourth connecting hole; 4, casing; 41, housing; 42, gearbox rear casing; 43, gearbox front cover; 5, motor; 51, motor shaft; 6, second planetary gear train; 61, second planetary gear; 62, second inner ring gear; 63, pin; 7, ball. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0030] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0031] like Figures 1 to 3 As shown, an electric tool according to a preferred embodiment of the present invention includes an output shaft 1, an impact mechanism 2 and a transmission mechanism 3. The transmission mechanism 3 is installed in a linkage manner between the output shaft 1 and the impact mechanism 2, and is used to transmit the torque generated by the impact mechanism 2 to the output shaft 1. The transmission mechanism 3 includes a connecting member 31 and a reduction gear set 32; the connecting member 31 is driven by the impact mechanism 2, and the connecting member 31 can rotate around its own axis; the reduction gear set 32 is installed in a linkage manner between the output shaft 1 and the connecting member 31, and the reduction gear set 32 is driven by the connecting member 31, and the reduction gear can drive the output shaft 1 to rotate around its own axis; wherein, the rotation speed of the connecting member 31 is greater than the rotation speed of the output shaft 1.

[0032] It is understood that the power tool of the present invention can be an impact wrench, etc. The reduction gear set 32 in the transmission mechanism 3 not only reduces the rotational speed but also increases the torque. The impact mechanism 2 can include an impact block. The connection member 31 is driven by the impact mechanism 2, which can be understood as: the impact block can drive the connection member 31 to rotate along the circumference of the connection member 31; or, the impact block can form a circumferential impact action on the connection member 31 along the circumference of the connection member 31, thereby driving the connection member 31 to rotate.

[0033] Taking an impact wrench as an example, the process of tightening a workpiece with an impact wrench can be divided into two stages. The first stage can be considered as the workpiece rotating rapidly with the impact wrench, during which the impact mechanism 2 does not generate a circumferential impact. The second stage is the tightening stage of the workpiece, i.e., the workpiece rotation speed is significantly reduced, during which the impact mechanism 2 generates a circumferential impact. Since the workpiece rotation is already slow at this stage and this rotation slows further as the tightening action intensifies, the effect of the reduction gear set 32 on the rotation speed is negligible at this stage. Therefore, the reduction gear set 32 mainly serves to increase the torque of the output shaft 1, tightening the workpiece as much as possible.

[0034] Compared with the impact wrench in the prior art, the power tool of the present invention can increase the torque of the output shaft 1 without changing the size of the striking block in the impact mechanism 2 and the power of the motor 5. Moreover, since the power tool of the present invention only adds a transmission mechanism 3 between the output shaft 1 and the impact mechanism 2 along the axial direction of the power tool, the radial size of the power tool increases less, which is conducive to the miniaturization of the power tool.

[0035] like Figures 1 to 3As shown, in a specific embodiment, the power tool of the present invention includes a housing 4, a motor 5 installed in the housing 4, and a plurality of second planetary gear trains 6. The second planetary gear train 6 plays the role of transmission connection between the motor 5 and the impact mechanism 2, that is, the power of the motor 5 is transmitted to the impact mechanism 2, so that the impact mechanism 2 can generate an impact force and drive the output shaft 1 to rotate. Specifically, the second planetary gear train 6 plays the role of speed reduction and torque increase, that is, the torque output by the motor 5 is transmitted to the impact mechanism 2 after the second planetary gear train 6 plays the role of speed reduction and torque increase. The motor 5 has a motor shaft 51 as a power output component, and the motor shaft 51 is connected to the second planetary gear train 6. The housing 4 includes a shell 41, a gearbox rear shell 42 and a gearbox front cover 43 that are connected to each other.

[0036] Specifically, such as Figure 3 As shown, the second planetary gear train 6 may include a sun gear (not shown) serving as an input component, a plurality of second planet gears 61 surrounding and meshing with the sun gear, a second inner ring gear 62 meshing with the plurality of second planet gears 61, and a plurality of pins 63 supporting the plurality of planet gears. The pins 63 correspond one-to-one with the second planet gears 61 and are connected to the drive shaft 21 of the impact mechanism 2. The second planet gears 61 are mounted on the pins 63 and are rotationally connected to the drive shaft 21 via the pins 63. The second inner ring gear 62 is fixedly mounted on the housing 4. The sun gear may be directly sleeved onto the motor shaft 51, with an interference fit between the sun gear and the motor shaft 51. In other embodiments, the sun gear may also be integral with the motor shaft 51.

[0037] In other embodiments, the motor 5 and the impact mechanism 2 may be connected via other gear assemblies.

[0038] It should be noted that if the reduction gear set 32 of the present invention is placed between the motor 5 and the impact mechanism 2, then the functions of the reduction gear set 32 and the second planetary gear system 6 can be considered similar. Since there are multiple second planetary gear systems 6 between the motor 5 and the impact mechanism 2, it is better to achieve the same effect by increasing the number of second planetary gear systems 6, that is, to increase torque by reducing speed. However, such an arrangement may cause the rotation speed of the striking block on the impact mechanism 2 to be too low, that is, the impact mechanism 2 may not be able to achieve a circumferential striking action. Therefore, the present invention sets a reduction gear set 32 between the impact mechanism 2 and the output shaft 1, that is, at this time, the rotation speed of the striking block in the impact mechanism 2 is sufficient to achieve a circumferential striking action, so that the impact mechanism 2 can output torque outward. The reduction gear set 32 increases the torque already generated by the impact mechanism 2 and then outputs it.

[0039] In one embodiment, the ratio of the rotational speed of the connecting member 31 to the rotational speed of the output shaft 1 is greater than or equal to 2. This configuration can significantly increase the torque; and the greater the ratio of the rotational speed of the connecting member 31 to the rotational speed of the output shaft 1, the greater the increase in torque.

[0040] Preferably, the ratio of the speed of the connecting member 31 to the speed of the output shaft 1 is 2 to 4. During the process of deceleration and torque increase of the reduction gear set 32, although the greater the ratio of the speed of the connecting member 31 to the speed of the output shaft 1, the greater the increase in torque, the greater the burden on the various components in the reduction gear set 32 and the various components in the power tool, that is, the higher the requirements for the inherent strength and stability of each component. Therefore, setting the ratio of the speed of the connecting member 31 to the speed of the output shaft 1 to 2 to 4 is a relatively reasonable range, which can achieve a relatively ideal increase in torque, match the inherent strength and stability requirements of each component, and balance the manufacturing cost and service life of each component.

[0041] The reduction gear set 32 includes an input gear 321 and an output member 322 that are connected in a transmission manner. The output member 322 is connected to the output shaft 1, and the input gear 321 is connected to the connecting member 31. The input gear 321 and the output member 322 can be directly connected in a transmission manner. For example, if the output member 322 is a gear, it meshes with the input gear 321. The input gear 321 and the output member 322 can also be indirectly connected in a transmission manner. That is, the input gear 321 and the output member 322 are connected through other components, and the other components include at least one gear component.

[0042] like Figures 2-4 As shown, in a specific embodiment, the reduction gear set 32 is a first planetary gear system, which includes an input gear 321, a plurality of first planetary gears 323 surrounding and meshing with the input gear 321, a first inner ring gear 324 meshing with the plurality of first planetary gears 323, and an output member 322 carrying the plurality of first planetary gears 323.

[0043] It will be appreciated that in the above embodiment, the input gear 321 is equivalent to the sun gear component in the first planetary gear train, that is, it serves as the power or torque input component in the reduction gear set 32; the input gear 321 is connected to the connecting member 31 and can rotate synchronously with the connecting member 31. The output member 322 can serve as the planet carrier in the first planetary gear train, and the output shaft 1 is connected to the output member 322 and can rotate synchronously with the output member 322.

[0044] The output member 322 is fixedly connected to the output shaft 1 ; the fixed connection may be an integral molding connection, welding, interference fit, clip connection, adhesive connection, riveting, or the like.

[0045] like Figure 5 and Figure 6As shown, in another specific embodiment, the reduction gear set 32 is a fixed-axis gear train, and the output member 322 is a gear. The fixed-axis gear train includes an input gear 321, a plurality of fixed gears 325 surrounding and meshing with the input gear 321, an output member 322 meshing with the plurality of fixed gears 325, and a gear carrier 326 supporting the plurality of fixed gears 325. The fixed gears 325 can be a double gear, and the fixed gears 325 include a first gear portion 3251 and a second gear portion 3252 coaxially arranged. The first gear portion 3251 meshes with the input gear 321, and the second gear portion 3252 meshes with the output member 322. The first gear portion 3251 and the second gear portion 3252 have different outer diameters. By designing the meshing relationship and gear ratio between the output member 322, the first gear portion 3251, the second gear portion 3252, and the input gear 321, the reduction gear set 32 functions to reduce speed and increase torque.

[0046] As will be understood, the gear frame 326 includes a fixed frame 3261, an end plate 3262, and a plurality of fixed shafts 3263, with the axial ends of the fixed shafts 3263 mounted on the fixed frame 3261 and the end plate 3262, respectively. The fixed frame 3261 has a second connecting hole 32611 extending axially, through which the output member 322 and / or the output shaft 1 partially penetrates and is rotatably connected to the second connecting hole 32611. The end plate 3262 has a third connecting hole 32621, through which the connecting member 31 penetrates and is rotatably connected to the third connecting hole 32621. The fixed frame 3261 is fixedly mounted within the housing 4. When the power tool is in operation, the fixed frame 3261 and the housing 4 do not rotate relative to each other. In other words, the fixed gear 325 rotates only on its own axis and does not revolve around the input gear 321.

[0047] The output member 322 is fixedly connected to the output shaft 1 ; the fixed connection may be an integral molding connection, welding, interference fit, clip connection, adhesive connection, riveting, or the like.

[0048] like Figure 7 and 8 As shown, in another specific embodiment, the output member 322 includes an inner gear ring portion 3221 and a connecting portion 3222, the connecting portion 3222 has a stop hole 3223, the output shaft 1 is plugged into the stop hole 3223 to form a stop structure, and the inner gear ring portion 3221 is engaged with the input gear 321.

[0049] It is understood that the output shaft 1 includes a stopper 11, which is plugged into the stopper hole 3223 to form a stopper structure. The stopper structure mainly serves to rotate the connecting portion 3222 and the stopper 11 together, that is, the output member 322 and the output shaft 1 rotate together.

[0050] Preferably, the anti-rotation portion 11 has at least one first anti-rotation surface 111, and the inner wall of the anti-rotation hole 3223 has at least one second anti-rotation surface 32231. The first anti-rotation surface 111 and the second anti-rotation surface 32231 are arranged opposite each other to form an anti-rotation structure. During the rotation of the connecting portion 3222 and the anti-rotation hole 3223, at least a portion of the second anti-rotation surface 32231 will abut against the first anti-rotation surface 111, generating a force that pushes the first anti-rotation surface 111, thereby generating a force that drives the anti-rotation portion 11 to rotate along its axial direction, thereby achieving synchronous rotation of the anti-rotation portion 11 and the anti-rotation hole 3223 (i.e., the connecting portion 3222).

[0051] In such Figure 7 and 8 In the embodiment shown, the stop portion 11 is rod-shaped, and the first stop surface 111 is arranged on its outer circumferential surface. The stop portion 11 may include multiple first stop surfaces 111 arranged along the circumferential direction, and the inner wall of the stop hole 3223 is also correspondingly provided with multiple second stop surfaces 32231 along its circumferential direction. The first stop surface 111 corresponds to the second stop surface 32231 one by one.

[0052] Furthermore, the anti-rotation portion 11 and the anti-rotation hole 3223 have an interference fit. This arrangement can make the connection between the anti-rotation portion 11 and the anti-rotation hole 3223 more stable. Of course, in other embodiments, the anti-rotation portion 11 and the anti-rotation hole 3223 do not need to have an interference fit, as long as the anti-rotation hole 3223 can drive the anti-rotation portion 11 to rotate synchronously.

[0053] In such Figure 7 and Figure 8 In the illustrated embodiment, the reduction gear assembly 32 further includes a positioning plate 327, which is fixedly mounted within the housing 4. The positioning plate 327 has a fourth connecting hole 3271 extending axially thereof. The connector 31 is inserted into the fourth connecting hole 3271 and rotatably connected thereto, thereby positioning and mounting the connector 31. The positioning plate 327 may have a plurality of weight-reducing holes to reduce the weight of the positioning plate 327.

[0054] Regardless of Figures 2 to 8 In any of the three specific embodiments shown, the input gear 321 and the connecting member 31 are fixedly connected, and the fixed connection can be an integral molding connection, welding, interference fit, snap connection, adhesive connection, riveting, etc.

[0055] Preferably, the input gear 321 is integrally connected to the connecting member 31. This arrangement can reduce the number of components and improve the connection strength between the input gear 321 and the connecting member 31.

[0056] like Figures 2 to 8In any of the above embodiments, the impact mechanism 2 has a drive shaft 21, and the end of the connecting member 31 facing the impact mechanism 2 has a first connecting hole 311, and the drive shaft 21 is plugged into the first connecting hole 311. This arrangement can play a role in axial positioning of the connecting member 31.

[0057] Furthermore, a ball 7 is mounted between the axial inner wall of the first connecting hole 311 and the drive shaft 21. The rolling motion of the ball 7 changes the friction between the axial inner wall of the first connecting hole 311 and the end face of the drive shaft 21 from sliding friction to rolling friction, thereby reducing wear between the drive shaft 21 and the connecting member 31 and extending the service life of both components.

[0058] like Figures 2 to 8 In any of the illustrated embodiments, a protrusion 312 is provided on the outer circumferential surface of the end of the connecting member 31 that faces the impact mechanism 2. When the striking block of the impact mechanism 2 rotates circumferentially, the striking block abuts against the protrusion 312, driving the protrusion 312 to rotate circumferentially. In other words, the impact mechanism 2 drives the connecting member 31 to rotate circumferentially. Circumferential rotation can also be considered as rotation about its own axial direction.

[0059] In such Figure 4 or Figure 5 In any of the embodiments shown, the output shaft 1 and the motor shaft 51 are on the same axis, so the operation thereof is more stable and the radial dimension is smaller.

[0060] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An electric tool, characterized in that: It includes an output shaft, an impact mechanism and a transmission mechanism. The transmission mechanism is installed in a linkage manner between the output shaft and the impact mechanism and is used to transmit the torque generated by the impact mechanism to the output shaft. The transmission mechanism includes: A connecting member, driven by the impact mechanism, capable of rotating around its own axis; a reduction gear set, which is installed in linkage between the output shaft and the connecting member, the reduction gear set is driven by the connecting member, and the reduction gear set can drive the output shaft to rotate around its own axis; Wherein, the rotation speed of the connecting member is greater than the rotation speed of the output shaft.

2. The electric tool according to claim 1, wherein: The ratio of the rotational speed of the connecting member to the rotational speed of the output shaft is greater than or equal to 2.

3. The electric tool according to claim 2, wherein: The ratio of the rotation speed of the connecting member to the rotation speed of the output shaft is 2-4.

4. The electric tool according to claim 1, wherein: The reduction gear set includes an input gear and an output member that are transmission-connected. The output member is connected to the output shaft, and the input gear is connected to the connecting member.

5. The electric tool according to claim 4, wherein: The reduction gear set is a first planetary gear system, which includes the input gear, a plurality of first planetary gears surrounding and meshing with the input gear, a first inner ring gear meshing with the plurality of first planetary gears, and the output member carrying the plurality of first planetary gears.

6. The electric tool according to claim 4, wherein: The reduction gear set is a fixed-axis gear system, and the output member is a gear. The fixed-axis gear system includes an input gear, a plurality of fixed gears surrounding and meshing with the input gear, the output member meshing with the plurality of fixed gears, and a gear carrier carrying the plurality of fixed gears. The fixed gear includes a first gear portion and a second gear portion coaxially arranged, the first gear portion meshing with the input gear, and the second gear portion meshing with the output member.

7. The electric tool according to claim 4, wherein: The output member includes an inner gear ring portion and a connecting portion, the connecting portion is provided with a rotation-stopping hole, the output shaft is plugged into the rotation-stopping hole to form a rotation-stopping structure, and the inner gear ring portion is meshed with the input gear.

8. The electric tool according to claim 4, wherein: The input gear is integrally connected to the connecting piece.

9. The electric tool according to claim 1, wherein: The impact mechanism has a driving shaft, and the end of the connecting piece facing the impact mechanism has a first connecting hole, and the driving shaft is plugged into the first connecting hole.

10. The electric tool according to claim 9, wherein: A ball is mounted on the axial inner wall of the first connecting hole and the driving shaft by clamping.

Images