Gearbox for electric wrench

Abstract

The invention provides a gearbox for an electric wrench. The gearbox comprises a shell, an end cover, a force input gear shaft, a force output gear shaft and a transition gear shaft, wherein the force input gear shaft, the force output gear shaft and the transition gear shaft are rotationally arranged in the shell and the end cover. The transition gear shaft is in transmission connection between the force input gear shaft and the force output gear shaft, the force input end of one end of the force input gear shaft penetrates through the end cover, and the force output end of one end of the force output gear shaft penetrates through the shell. The input gear shaft, the output gear shaft and the transition gear shaft are in transmission connection through a first bevel gear set and a second bevel gear set at the same time, and the first bevel gear set comprises first bevel gears located on the input gear shaft, the output gear shaft and the transition gear shaft. The second bevel gear set comprises second bevel gears located on the force input gear shaft, the force output gear shaft and the transition gear shaft, the first bevel gears of the force input gear shaft, the force output gear shaft and the transition gear shaft and the respective second bevel gears are symmetrically arranged and are opposite in rotation direction, axial force can be counteracted to a great extent, transmission stability is high, and the service life is long.

Description

Technical Field

[0001] This invention relates to the field of electric wrenches, and more particularly to a gearbox for electric wrenches. Background Technology

[0002] Electric wrenches are indispensable power tools in modern industry and household work. They can convert the rotational power of an electric motor into high-intensity, controllable torque output. Many electric wrenches use motors connected to gearboxes.

[0003] If a gearbox uses spur gears, the single-tooth meshing range accounts for a large proportion, leading to high fluctuations in output torque. Furthermore, the tooth contact line is parallel to the axis, resulting in significant stress concentration, which significantly reduces gear performance and lifespan. Many existing gearboxes use helical gears. Helical gears offer progressive meshing, resulting in very smooth impact and load changes, high transmission stability, uniform load distribution, and low stress concentration. However, helical gear drives experience large axial force fluctuations, which can easily cause axial movement of the gears, leading to abnormal displacement of the tooth contact area and affecting the gearbox's lifespan.

[0004] Therefore, it is necessary to provide a gearbox for electric wrenches to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a gearbox for electric wrenches to solve the problem in the prior art where gearboxes using helical gear transmission have large axial force fluctuations and are prone to axial movement of the gears.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a gearbox for an electric wrench, comprising: a housing, an end cover, and an input gear shaft, an output gear shaft, and a transition gear shaft rotatably disposed in the housing and the end cover, wherein the end cover and the housing are positioned and connected by a locating pin, and the end cover and the housing are locked together by screws. The transition gear shaft is connected between the input gear shaft and the output gear shaft. The input end of the input gear shaft passes through the end cover, and the output end of the output gear shaft passes through the housing. The input gear shaft, the output gear shaft, and the transition gear shaft are simultaneously connected by a first helical gear set and a second helical gear set. The first helical gear set includes a first helical gear located on the input gear shaft, the output gear shaft, and the transition gear shaft. The second helical gear set includes a second helical gear located on the input gear shaft, the output gear shaft, and the transition gear shaft. The first and second helical gears on the input gear shaft are symmetrically arranged and rotate in opposite directions. The first and second helical gears on the output gear shaft are symmetrically arranged and rotate in opposite directions. The first and second helical gears on the transition gear shaft are symmetrically arranged and rotate in opposite directions.

[0007] In this invention, one end of each tooth of the first helical gear and one end of each tooth of the second helical gear are connected as an integral structure.

[0008] In this invention, two transition gear shafts with a speed ratio of 1:1 are connected between the input gear shaft and the output gear shaft, and the input gear shaft, the transition gear shaft and the output gear shaft are arranged in a straight line.

[0009] In this invention, one end of the transition gear shaft is rotatably connected to the housing via a needle roller bearing and an end face ball bearing, and the other end of the transition gear shaft is rotatably connected to the end cover via a needle roller bearing and an end face ball bearing. Both ends of the transition gear shaft are provided with a first shoulder on their circumferential sides. The end face ball bearing at one end is limited between the housing and the first shoulder, and the end face ball bearing at the other end is limited between the end cover and the first shoulder.

[0010] In this invention, the input end of the input gear shaft is rotatably connected to the end cover via a needle roller bearing and a skeleton oil seal, and the end of the input gear shaft away from the input end is rotatably connected to the housing via a needle roller bearing and two end face ball bearings. The output end of the output gear shaft is rotatably connected to the housing via a needle roller bearing and a skeleton oil seal, and the end of the output gear shaft away from the output end is rotatably connected to the housing via a needle roller bearing and two end face ball bearings.

[0011] In this configuration, an inner retaining ring is provided between the two end face ball bearings of the input gear shaft and the output gear shaft. The inner retaining ring is connected to the end cover or the inner hole of the housing. A shaft retaining ring is connected to both the input gear shaft and the output gear shaft. A second shoulder is provided on the circumference of both the input gear shaft and the output gear shaft. The two end face ball bearings are limited between the shaft retaining ring and the second shoulder.

[0012] In addition, the end cap corresponding to the position of the output gear shaft and the housing corresponding to the position of the input gear shaft are both provided with mounting openings for mounting end face ball bearings, and threaded plugs are closed at the mounting openings.

[0013] In this invention, the outer surface of the end cap through which the input gear shaft passes is provided with a positioning protrusion for connection with a power device, and the positioning protrusion is arranged around the input gear shaft.

[0014] Furthermore, the outer surface of the end cap is provided with a plurality of connection holes for connecting the power device. The plurality of connection holes are located on the periphery of the positioning protrusion ring. The end cap protrudes from the outer peripheral side of the housing, parallel to the input gear shaft and close to the input gear shaft.

[0015] In this invention, the outer peripheral side of the housing and the end cap that is parallel to the input gear shaft and away from the input gear shaft is configured as a rounded structure.

[0016] Compared with the prior art, the advantages of this invention are as follows: the gearbox for electric wrenches of this invention can greatly offset axial force by symmetrically arranging a first helical gear and a second helical gear with opposite directions of rotation on the input gear shaft, the output gear shaft and the transition gear shaft. The gearbox has high running stability and long service life. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments are briefly introduced below. The drawings described below are only the corresponding drawings of some embodiments of the present invention.

[0018] Figure 1 This is a schematic diagram of the gearbox for an electric wrench according to the present invention.

[0019] Figure 2 This is an exploded structural diagram of the gearbox for an electric wrench according to the present invention.

[0020] Figure 3 This is a cross-sectional view of the gearbox for an electric wrench according to the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The directional terms mentioned in this invention, such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", "top" and "bottom", are only for reference to the orientation of the accompanying drawings. The directional terms used are for the purpose of explaining and understanding this invention, and are not intended to limit this invention.

[0023] The terms "first" and "second" used in the terminology of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance, nor as limiting the order of events.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, a connection can be a detachable connection or a connection of an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components or an interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In the existing technology, the use of helical gear transmission in gearboxes has the problem of large axial force fluctuation, which can easily cause axial movement of the gears, resulting in abnormal displacement of the tooth surface contact area and affecting the service life of the gearbox.

[0026] The following is a preferred embodiment of a gearbox for an electric wrench provided by the present invention, which can solve the above-mentioned technical problems.

[0027] Please refer to Figure 1 , Figure 2 and Figure 3 In the diagram, units with similar structures are represented by the same labels.

[0028] This embodiment provides a gearbox for an electric wrench, which includes: a housing 11, an end cover 12, and an input gear shaft 13, an output gear shaft 14, and a transition gear shaft 16 rotatably disposed within the housing 11 and the end cover 12.

[0029] The end cap 12 and the housing 11 are positioned and connected by a locating pin 124, and the end cap 12 and the housing 11 are then locked together by a screw 123.

[0030] In this embodiment, the transition gear shaft 16 is connected between the input gear shaft 13 and the output gear shaft 14. The input end of the input gear shaft 13 passes through the end cover 12 for connecting a power device, such as a motor. The output end of the output gear shaft 14 passes through the housing 11 for wrench operation. The output end can be a four-corner wrench, a hexagonal wrench, etc., or it can be a connector that can be detachably connected to the four-corner wrench, hexagonal wrench, etc.

[0031] The input gear shaft 13, output gear shaft 14, and transition gear shaft 16 are simultaneously connected by a first helical gear set 21 and a second helical gear set 22. The first helical gear set 21 includes first helical gears 21 located on the input gear shaft 13, output gear shaft 14, and transition gear shaft 16, and the second helical gear set 22 includes second helical gears 22 located on the input gear shaft 13, output gear shaft 14, and transition gear shaft 16. The first helical gears 21 and second helical gears 22 on the input gear shaft 13 are symmetrically arranged and rotate in opposite directions. The first helical gears 21 and second helical gears 22 on the output gear shaft 14 are symmetrically arranged and rotate in opposite directions. The first helical gears 21 and second helical gears 22 on the transition gear shaft 16 are symmetrically arranged and rotate in opposite directions. This arrangement can largely counteract axial forces, resulting in high transmission smoothness and a long service life.

[0032] Please refer to Figure 2 and Figure 3 In this invention, one end of each tooth of the first helical gear 21 and one end of each tooth of the second helical gear 22 are connected to form an integral structure, which is stable and has high strength.

[0033] In this invention, two transition gear shafts 16 with a speed ratio of 1:1 are connected between the input gear shaft 13 and the output gear shaft 14. The input gear shaft 13, transition gear shaft 16, and output gear shaft 14 are arranged in a straight line. This allows for a flexible increase in the actual distance between the input and output shafts without changing the transmission ratio, avoiding interference between the power unit and the product to be operated, and making the gearbox layout adaptable to the space between the input and output. Simultaneously, the power flow is transmitted through multiple tooth surfaces, dispersing the bending and contact stresses on individual gears, improving the overall load-bearing capacity and fatigue life, reducing transmission fluctuations caused by tooth profile errors and installation errors, and making operation smoother.

[0034] Please refer to Figure 2 and Figure 3 In this embodiment, one end of the transition gear shaft 16 is rotatably connected to the housing 11 through a needle roller bearing 17 and an end face ball bearing 18, and the other end of the transition gear shaft 16 is rotatably connected to the end cover 12 through a needle roller bearing 17 and an end face ball bearing 18.

[0035] Specifically, the transition gear shaft 16 has a first shoulder on both sides of its circumference. The end face ball bearing 18 at one end is positioned between the housing 11 and the first shoulder, and the end face ball bearing 18 at the other end is positioned between the end cover 12 and the first shoulder. The end face ball bearing can withstand the load in the axial direction and provide axial positioning or constraint for the transition gear shaft 16 to prevent it from moving axially.

[0036] In this embodiment, the input end of the input gear shaft 13 is rotatably connected to the end cover 12 via a needle roller bearing 17 and a skeleton oil seal 1B, and the end of the input gear shaft 13 away from the input end is rotatably connected to the housing 11 via a needle roller bearing 17 and two end face ball bearings 18.

[0037] The output end of the output gear shaft 14 is rotatably connected to the housing 11 via a needle roller bearing 17 and a skeleton oil seal 1B. The end of the output gear shaft 14 away from the output end is rotatably connected to the housing 11 via a needle roller bearing 17 and two end face ball bearings 18.

[0038] By setting two end face ball bearings 18 at one end of the input gear shaft 13 and the output gear shaft 14, the input gear shaft 13 and the output gear shaft 14 can be positioned or constrained in two axial directions to prevent axial movement. At the same time, it solves the problem that the installation space at the input end of the input gear shaft 13 and the output end of the output gear shaft 14 is insufficient, making it inconvenient to install end face ball bearings.

[0039] In this configuration, an inner retaining ring 19 is provided between the two end face ball bearings 18 of the input gear shaft 13 and the output gear shaft 14. The inner retaining ring 19 is connected to the end cover 12 or the inner hole of the housing 11. A shaft retaining ring 1A is connected to both the input gear shaft 13 and the output gear shaft 14. A second shoulder is provided on the circumference of both the input gear shaft 13 and the output gear shaft 14. The two end face ball bearings 18 are limited between the shaft retaining ring 1A and the second shoulder, thereby forming a stable fixation for the two end face ball bearings 18.

[0040] In addition, the end cover 12 is provided with an installation opening for mounting the end face ball bearing 18 at the position corresponding to the output gear shaft 14, and the housing 11 is provided with an installation opening corresponding to the input gear shaft 13. A threaded plug 15 is connected to the installation opening to seal it. After the end face ball bearing 18 is installed, it will be filled with grease. The threaded plug 15 can seal the installation opening to prevent the grease from flowing out.

[0041] Please refer to Figure 1 In this embodiment, the outer surface of the end cover 12 through which the input gear shaft 13 passes is provided with a positioning protrusion 121 for connection with the power device, and the positioning protrusion 121 is arranged around the input gear shaft 13.

[0042] Furthermore, the outer surface of the end cap 12 is provided with a plurality of connection holes 122 for connecting the power unit, and the plurality of connection holes 122 are located on the periphery of the positioning protrusion ring 121. The end cap 12 protrudes from the outer peripheral side of the housing 11 parallel to the input gear shaft 13 and close to the input gear shaft 13, so as to facilitate the setting of the connection holes 122, and also to facilitate the holding of the gearbox to connect to the power unit.

[0043] In this embodiment, the outer peripheral side of the housing 11 and the end cap 12 that is parallel to the input gear shaft 13 and away from the input gear shaft 13 is set as a rounded structure, which makes the structure more compact and smaller in size, and avoids interference with the product to be operated.

[0044] The working principle of this invention is as follows: One end of the input gear shaft 13 is connected to a power device. The power device inputs power through the input end of the input gear shaft 13, driving the input gear shaft 13 to rotate. A pair of helical gears 21 and 22 with opposite directions of rotation are symmetrically arranged on the input gear shaft 13. This pair of helical gears simultaneously meshes with corresponding helical gears (i.e., another pair of helical gears with opposite directions of rotation) on the two transition gear shafts 16, forming a parallel transmission path between the first and second helical gear sets.

[0045] Two intermediate gear shafts 16 are arranged in parallel, with two pairs of helical gears on them meshing with corresponding helical gears on the input gear shaft 13 and the output gear shaft 14, respectively. This ensures that the axial force generated by the helical gear meshing on each gear shaft is generated into opposing and approximately equal axial components within the shaft due to the opposite rotation directions of the first helical gear 21 and the second helical gear 22. These components cancel each other out or significantly weaken the force during transmission. This effectively solves the problem of large axial force and easy axial movement of gears in traditional single helical gear transmissions, significantly improving transmission smoothness.

[0046] Power is transmitted to the output gear shaft 14 via two transition gear shafts 16, and the combined rotational motion and torque are finally output from the output end of the output gear shaft 14 to perform operations such as tightening or loosening bolts.

[0047] In addition, the gearbox employs a combination of face ball bearings 18 and needle roller bearings 17 to ensure precise radial and axial positioning and reliable support for each gear shaft, further suppressing possible axial displacement and vibration, and enhancing the overall structural rigidity and operational stability.

[0048] The gearbox for electric wrenches in this preferred embodiment can largely counteract axial forces by symmetrically arranging a first helical gear and a second helical gear with opposite directions of rotation on the input gear shaft, output gear shaft, and transition gear shaft. The gearbox has high running stability and long service life.

[0049] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A gearbox for an electric wrench, characterized in that, include: The housing, the end cover, and the input gear shaft, the output gear shaft, and the transition gear shaft rotatably disposed within the housing and the end cover are provided. The end cover and the housing are positioned and connected by a locating pin and locked together by screws. The transition gear shaft is connected between the input gear shaft and the output gear shaft. The input end of the input gear shaft passes through the end cover, and the output end of the output gear shaft passes through the housing. The input gear shaft, the output gear shaft, and the transition gear shaft are simultaneously connected by a first helical gear set and a second helical gear set. The first helical gear set includes a first helical gear located on the input gear shaft, the output gear shaft, and the transition gear shaft. The second helical gear set includes a second helical gear located on the input gear shaft, the output gear shaft, and the transition gear shaft. The first and second helical gears on the input gear shaft are symmetrically arranged and rotate in opposite directions. The first and second helical gears on the output gear shaft are symmetrically arranged and rotate in opposite directions. The first and second helical gears on the transition gear shaft are symmetrically arranged and rotate in opposite directions.

2. The gearbox for an electric wrench according to claim 1, characterized in that, One end of each tooth of the first helical gear and one end of each tooth of the second helical gear are connected as a single unit.

3. The gearbox for an electric wrench according to claim 1, characterized in that, The input gear shaft and the output gear shaft are connected by two transition gear shafts with a speed ratio of 1:

1. The input gear shaft, the transition gear shaft and the output gear shaft are arranged in a straight line.

4. The gearbox for an electric wrench according to claim 1, characterized in that, One end of the transition gear shaft is rotatably connected to the housing via a needle roller bearing and an end face ball bearing, and the other end of the transition gear shaft is rotatably connected to the end cover via a needle roller bearing and an end face ball bearing. Both ends of the transition gear shaft are provided with a first shoulder on their circumferential sides. The end face ball bearing at one end is limited between the housing and the first shoulder, and the end face ball bearing at the other end is limited between the end cover and the first shoulder.

5. The gearbox for an electric wrench according to claim 1, characterized in that, The input end of the input gear shaft is rotatably connected to the end cover via a needle roller bearing and a skeleton oil seal, and the end of the input gear shaft away from the input end is rotatably connected to the housing via a needle roller bearing and two end face ball bearings. The output end of the output gear shaft is rotatably connected to the housing via a needle roller bearing and a skeleton oil seal, and the end of the output gear shaft away from the output end is rotatably connected to the housing via a needle roller bearing and two end face ball bearings.

6. The gearbox for an electric wrench according to claim 5, characterized in that, An inner retaining ring is provided between the two end face ball bearings of the input gear shaft and the output gear shaft. The inner retaining ring is connected to the end cover or the inner hole of the housing. A shaft retaining ring is connected to both the input gear shaft and the output gear shaft. A second shoulder is provided on the circumference of both the input gear shaft and the output gear shaft. The two end face ball bearings are limited between the shaft retaining ring and the second shoulder.

7. The gearbox for an electric wrench according to claim 5, characterized in that, The end cap corresponding to the output gear shaft and the housing corresponding to the input gear shaft are both provided with mounting openings for mounting end face ball bearings, and threaded plugs are closed at the mounting openings.

8. The gearbox for an electric wrench according to claim 1, characterized in that, The outer surface of the end cap, through which the input gear shaft passes, is provided with a positioning protrusion for connection with a power device, and the positioning protrusion is arranged around the input gear shaft.

9. The gearbox for an electric wrench according to claim 8, characterized in that, The outer surface of the end cap is provided with a plurality of connection holes for connecting the power device. The plurality of connection holes are located on the periphery of the positioning protrusion ring. The end cap protrudes from the outer peripheral side of the housing, parallel to the input gear shaft and close to the input gear shaft.

10. The gearbox for an electric wrench according to claim 1, characterized in that, The outer peripheral side of the housing and the end cap, which is parallel to the input gear shaft and away from the input gear shaft, is rounded.

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