CN217177298U - An automatic two-speed torque wrench - Google Patents

Abstract

The utility model discloses an automatic two-speed torque wrench, comprising: a casing assembly; a planetary gear assembly, wherein the planet comprises a connected power transmission part, a low-speed gear adjustment part and a high-speed gear adjustment part; a power input part, the One end of the power input part extends into the casing assembly and meshes with the power transmission part for transmission; the power output part, one end of the power output part extends into the casing assembly and meshes with the power transmission part for transmission; the high-speed gear ring, so The high-speed gear ring is rotatably arranged in the casing assembly and meshes with the high-speed gear adjusting portion; the low-speed gear ring is rotatably arranged in the casing assembly and meshes with the low-speed gear adjusting portion; Adjustment assembly, the gear adjustment assembly cooperates with the casing assembly to change the limit and fixation of the high-speed gear ring gear or the low-speed gear ring gear through a preset torque value; compared with the prior art, the utility model has higher working efficiency. high.

Description

An automatic two-speed torque wrench

technical field

The utility model relates to the technical field of torque wrench structures, in particular to an automatic double-speed torque wrench.

Background technique

Electric torque wrenches are usually used for the disassembly and assembly of screw nuts, especially for screw nuts that require torque accuracy.

Existing torque wrenches use multi-stage deceleration to achieve a low-speed, high-torque output for work. For example, the patent document with the application number CN201821223432.9 discloses an electric torque increasing wrench, including a wrench shell, a driving device , Input shaft, output shaft and torque increasing device, wherein the input shaft and output shaft are coaxially installed in the wrench housing through the torque increasing device, one end of the input shaft is fixedly connected with the output end of the drive device outside one end of the wrench housing, and the output shaft One end extends out from the other end of the wrench shell; the outside of the wrench shell is provided with a handle.

The purpose is to perform multi-stage deceleration through the multi-stage star gear transmission mechanism and the bearing in the torque increasing device to increase the torque, but in actual work, the screw nut does not need a lot of torque at the beginning during the tightening process. When twisting, a large torque force is required only when the resistance is large in the last few turns; and the wrench in the above patent documents has been used to fasten the screw nut at a low speed and high torque, which has the problem of low work efficiency. .

Utility model content

In view of the deficiencies in the prior art, the purpose of this utility model is to provide an automatic two-speed torque wrench, so as to solve the problem that in the prior art, the wrench has been tightening the screw nut in a low-speed and high-torque manner. The problem of low work efficiency.

In order to achieve the above purpose, the utility model adopts the following technical scheme: an automatic two-speed torque wrench, comprising:

Chassis assembly;

A multi-planetary gear assembly, the multi-planetary gear assembly is rotatably arranged in the casing assembly and includes a connected power transmission part, a low-speed gear adjustment part and a high-speed gear adjustment part;

a power input part, one end of the power input part extends into the casing assembly and engages with the power transmission part for transmission;

a power output part, one end of the power output part extends into the casing assembly and engages with the power transmission part for transmission;

a high-speed gear ring gear, the high-speed gear ring gear is rotatably arranged in the casing assembly and meshes with the high-speed gear adjusting part;

a low-speed gear ring gear, the low-speed gear ring gear is rotatably arranged in the casing assembly and meshes with the low-speed gear adjusting part;

a gear adjustment component, the gear adjustment component cooperates with the casing assembly to change the limit fixation of the high-speed ring gear or the low-speed ring gear by a preset torque value;

When in use, the casing assembly is fixed to transmit torque; and when the high-speed ring gear is limited and fixed, the output speed ratio on the power output part is smaller than the output speed ratio on the power output part when the low-speed ring gear is limited and fixed.

Working principle: When in use, fix the casing assembly to balance the torque force output by the power output. At this time, the torque resistance of the screw nut is low, and the gear adjustment component is used to limit and fix the high-speed gear ring gear, and the low-speed gear ring gear is not The force follows the rotation state, the low-speed ring gear does not participate in the speed ratio conversion, and the high-speed ring gear and the high-speed adjustment part are converted to obtain a relatively low speed ratio. At this time, the power output part outputs a relatively high speed, and the generated torque is relatively It is small and can quickly fasten the screw nuts in the early stage; when the screw nuts are tightened in the last few turns, the resistance generated on the power output part increases significantly, and the torque of the high-speed ring gear increases under the reaction force So that when the preset torque value is exceeded, the gear adjustment component is switched to the low-speed ring gear and the limit is fixed. The low-speed adjustment part is converted into a relatively high speed ratio. At this time, the power output part outputs a relatively low speed, and the generated torque is relatively large, which can provide enough force for the tightening between the screws and nuts to efficiently The tightening between the screw and nuts is completed; the operation of the whole process is due to the automatic switching of the gear adjustment component with the change of torque to fix the limit between the high-speed gear ring gear and the low-speed gear ring gear, which is reasonable on the power output part. Adjust the speed and torque to effectively tighten the screw nut.

Further, the multi-planetary gear assembly also includes a planetary carrier rotatably arranged in the casing assembly, and the power transmission part, the low-speed gear adjustment part and the high-speed gear adjustment part are rotatably arranged inside and outside the planetary carrier from bottom to top. The transmission part, the low-speed adjustment part and the high-speed adjustment part all include a plurality of planetary gears arranged in the circumferential direction and rotatably penetrated inside and outside the planet carrier, and a plurality of the power transmission part, the low-speed adjustment part and the high-speed adjustment part The planetary gears are connected in a one-to-one correspondence in the vertical direction, and the number of teeth of the planetary gear in the power transmission part, the number of teeth of the planetary gear in the low-speed adjustment part, and the number of teeth of the planetary gear in the high-speed adjustment part decrease in turn, and the power transmission The planetary gears of the power input part are meshed with the outside of one end of the power input part and are meshed with the inside of one end of the power output part; the planetary gears of the low-speed adjustment part are meshed with the inside of the low-speed ring gear; Inside the high gear ring gear.

Further, an installation space is formed between the casing assembly and the high-speed gear ring gear and the low-speed gear ring gear, and the gear position adjustment assembly includes a gear shift return ring slidably arranged in the installation space, and one end of the gear shift return ring is connected to the The inner walls of the installation space are connected by springs, and the other end of the shift return ring is provided with a plurality of installation holes along its circumferential direction, and a shift steel ball is rotated in each installation hole. There are multiple shift oblique grooves in the circumferential direction, and a plurality of straight grooves are opened on the outer wall of the low-speed gear ring along its circumferential direction. The number of balls; when the limit of the high-speed gear ring gear is fixed, a plurality of shift steel balls abut between the multiple shift chute and the inner wall of the casing assembly in one-to-one correspondence; when the low-speed gear ring gear is limited and fixed, The plurality of shifting steel balls abut against the plurality of straight grooves and the inner wall of the casing assembly in a one-to-one correspondence.

Further, each of the shifting oblique grooves is a first notch groove, the notch of the first notch groove is arranged toward the low gear ring gear, and the width of the first notch groove gradually decreases from one end of the notch to the other end.

Further, each of the straight grooves is a second notch groove, the notch of the second notch groove is arranged toward the high-speed gear ring gear, and the width of the second notch groove gradually increases from one end of the notch to the other end.

Further, the casing assembly includes a casing and a reaction arm sleeve that is connected in rotation after one end is inserted into the casing. One end of the input part freely passes through the casing and then penetrates into the force arm sleeve to engage with the power transmission part.

Further, the power output part includes a ring gear segment meshed on the outside of the power transmission part and a power output shaft connected with the ring gear segment, and one end of the power output shaft away from the ring gear segment freely protrudes from the reaction arm casing.

Further, the casing assembly further includes a reaction arm fixedly connected to the outer wall of the reaction arm casing.

Further, the number of the shifting inclined grooves and the straight grooves is multiple times the number of the shifting steel balls.

Compared with the prior art, the utility model has the following beneficial effects:

This automatic two-speed torque wrench includes a casing assembly, a power transmission part, a low-speed gear adjustment part, a high-speed gear adjustment part, a power input part, a power output part, a high-speed gear ring gear, a low-speed gear ring gear, and gear adjustment components. In the matching of screw and nut, the method of high speed and low torque is used for tightening, and then it is automatically adjusted to the method of low speed and high torque for tightening, which greatly improves the work efficiency in the process of screw and nut tightening.

Description of drawings

1 is a partial cross-sectional view of an embodiment of the present utility model;

FIG. 2 is a schematic structural diagram of a shift oblique groove and a straight groove in an embodiment of the present invention.

The reference signs in the accompanying drawings include: high-speed gear ring gear 1, low-speed gear ring gear 2, casing 3, reaction arm sleeve 4, positioning screw 5, reaction arm 6, planet carrier 7, planetary gear 8, Shift return ring 9 , spring 10 , shift steel ball 11 , shift oblique groove 12 , straight groove 13 , power input shaft tooth 14 , ring gear segment 15 , power output shaft 16 , limit slot 17 .

Detailed ways

Below by specific embodiment, the present utility model is described in further detail:

As shown in FIG. 1, an embodiment of the present utility model proposes an automatic two-speed torque wrench, which includes a casing assembly, a multi-planetary gear assembly, a power input portion, a power output portion, a high-speed gear ring gear 1, and a low-speed gear tooth Ring 2 and gear adjustment assembly, the multi-planetary gear assembly is rotatably arranged in the casing assembly and includes a connected power transmission part, a low-speed adjustment part and a high-speed adjustment part; one end of the power input part extends into The casing assembly engages with the power transmission part for transmission, and one end of the power output part extends into the casing assembly and engages with the power transmission part for transmission; the high-speed gear ring gear 1 is rotatably arranged in the casing assembly and is Engaged with the high-speed gear adjustment part, the low-speed gear ring gear 2 is rotatably arranged in the casing assembly and meshed with the low-speed gear adjustment part, the gear position adjustment component, the gear position adjustment component cooperates with the casing assembly to The high-speed ring gear 1 or the low-speed ring gear 2 is limited and fixed by changing the preset torque value; when in use, the casing assembly is fixed to transmit torque; and when the high-speed ring gear 1 is limited and fixed, the power output part is fixed. The output speed ratio of is smaller than the output speed ratio on the power output part when the low-speed ring gear 2 is limited and fixed.

In this embodiment: during use, the casing 3 assembly is fixed to balance the torque force output by the power output part. At this time, the torque resistance of the screw nut is low, and the gear adjustment component is used to limit and fix the high-speed gear ring gear 1. The gear ring gear 2 is in a state of unforced following rotation, the low gear ring gear 2 does not participate in the speed ratio conversion, and the high gear ring gear 1 and the high gear adjustment part are converted to obtain a relatively lower speed ratio. High speed, the torque generated is relatively small, which can quickly fasten the screw nuts in the early stage; when the screw nuts are tightened in the last few turns, the resistance generated on the power output increases significantly, and under the reaction force When the torque of the high-speed gear ring gear 1 is increased so that it exceeds the preset torque value, the gear adjustment component switches to limit and fix the low-speed gear ring gear 2, the high-speed gear ring gear 1 is in a state of following rotation without force, and the high-speed gear ring gear 1 does not participate in the speed ratio conversion. The low-speed ring gear 2 and the low-speed adjustment part are converted to obtain a relatively high speed ratio. At this time, the power output part outputs a relatively low speed and generates a relatively large torque, which can be used for the screw nut. The tightening between the screws provides enough force to efficiently complete the tightening between the screw and nuts; the entire process runs because the automatic shifting of the gear adjustment assembly with the change of torque is used for the high-speed gear ring gear 1 and the low-speed gear ring gear. The limit between 2 is fixed, so that the speed and torque can be adjusted reasonably on the power output part, so as to efficiently tighten the screw nut.

This automatic two-speed torque wrench includes a casing assembly, a power transmission part, a low-speed gear adjustment part, a high-speed gear adjustment part, a power input part, a power output part, a high-speed gear ring gear 1, a low-speed gear ring gear 2, and gear adjustment components , to first use high speed and low torque to tighten the screw nut, and then automatically adjust to low speed and high torque for tightening, which greatly improves the work efficiency in the screw nut tightening process. .

As shown in FIG. 1 , according to another embodiment of the present utility model, in the automatic two-speed torque wrench, the casing assembly includes a casing 3 and a rotatable connection with one end inserted in the casing 3 . Reaction arm casing 4.

In this embodiment, after one end of the reaction arm casing 4 is inserted into the casing 3, it is limited by the positioning screw 5, so that the reaction arm casing 4 and the casing 3 can be connected. It rotates relatively and cannot move in the axial direction; the adopted casing 3 includes a cylindrical segment and a limiting segment integrally formed on the inner side of one end of the cylindrical segment, and an annular space is formed between the limiting segment and the cylindrical segment; When the limit section is in contact with the high-speed gear ring gear 1, the high-speed gear ring gear 1 is installed and limited; the reaction arm sleeve 4 includes a large cylinder section inserted in the cylindrical section and a small cylinder section connected to one end of the large cylinder section. In the cylinder section, the inner wall of the large cylinder section of the reaction arm casing 4 is provided with limit grooves 17 with the same number as the shift steel balls 11. The ring gear steel ball 11 can only move axially along the high-speed gear ring gear 1 to limit and fix the high-speed gear ring gear 1 and the low-speed gear ring gear 2; The shell 3 and the reaction arm casing 4 are fixed, and the structural design of the reaction arm casing 4 is to reasonably arrange the multi-planetary gear assembly and the power output part.

In order to better fix the casing assembly to transmit the reaction force to increase the torque of the high-speed gear ring gear 1 during use, so that the limit fixation of the high-speed gear ring gear 1 by the gear adjustment assembly is adjusted to the low-speed gear ring gear 1. The limit of the gear ring 2 is fixed; the reaction arm 6 on the outer wall of the reaction arm sleeve 4 is used, by fixing the reaction arm 6, the power output part rotates to output power.

As shown in FIG. 1 , according to another embodiment of the present invention, in the automatic two-speed torque wrench, the multi-planetary gear assembly further includes a planetary carrier 7 rotatably arranged in the casing assembly, and the power The transmission part, the low-speed adjustment part and the high-speed adjustment part are rotatably arranged inside and outside the planet carrier 7 from bottom to top. The plurality of planetary gears 8 inside and outside the frame 7, the plurality of planetary gears 8 in the power transmission part, the low-speed adjustment part and the high-speed adjustment part are connected in one-to-one correspondence in the vertical direction as a whole, and the planetary gears in the power transmission part The number of teeth of 8, the number of teeth of the planetary gear 8 in the low-speed adjustment part, and the number of teeth of the planetary gear 8 in the high-speed adjustment part decrease successively, and the plurality of planetary gears 8 of the power transmission part are meshed with one end of the power input part. Inside one end of the power output part, the planetary gears 8 of the low-speed adjusting part mesh with the inside of the low-speed ring gear 2 , and the multiple planetary gears 8 of the high-speed adjusting part are meshed with the inside of the high-speed ring gear 1 .

In this embodiment, the power transmission part, the low-speed adjustment part and the high-speed adjustment part are all composed of three planetary gears 8 arranged in a ring, and three of the power transmission part, the low-speed adjustment part and the high-speed adjustment part The planetary gears 8 form three rows in the vertical direction, each row includes a power transmission part, a low-speed gear adjustment part and a planetary gear 8 in the high-speed gear adjustment part, and the three planetary gears 8 in each row are connected as a whole, Specifically, it can be fixed together by key connection. In this embodiment, the three planetary gears 8 in each row are integrally formed to form an integrated structure, and the radius and the number of gear teeth of the three planetary gears 8 in each row are the same. It decreases sequentially from bottom to top; among them, the planet carrier 7 has a cylindrical structure and three mounting holes are opened on its outer wall along its circumferential direction, and the middle of the three planetary gears 8 in each row is correspondingly mounted in one mounting hole, A part of the three planetary gears 8 in each row is arranged in the planet carrier 7 in rotation, and another part is arranged outside the planet carrier 7 in rotation.

During the operation of the automatic two-speed torque wrench, the planet carrier 7 is always rotating in the casing assembly. The input part, the power output part, the high-speed gear ring gear 1 and the low-speed gear ring gear 2 cooperate to output high speed and low torque on the power output part when the high-speed gear ring gear 1 is limited and fixed; in the low-speed gear ring gear 2 When the limit is fixed, low speed and high torque are output on the power output part to efficiently fasten the screw nut.

As shown in FIG. 1 , according to another embodiment of the present invention, in the automatic two-speed torque wrench, an installation space is formed between the casing assembly and the high-speed gear ring gear 1 and the low-speed gear ring gear 2 , the gear adjustment assembly includes a shift return ring 9 slidably arranged in the installation space, one end of the shift return ring 9 is connected with the inner wall of the installation space through a spring 10, and the other end of the shift return ring 9 is along the A plurality of installation holes are opened in the circumferential direction, and each installation hole is rotatably provided with a shifting steel ball 11. The outer wall of the high-speed gear ring gear 1 is provided with a plurality of shifting inclined grooves 12 along its circumferential direction, and the low-speed gear tooth There are a plurality of straight grooves 13 on the outer wall of the ring 2 along its circumferential direction. When fixed, the plurality of shift steel balls 11 are in a one-to-one correspondence between the plurality of shift chute 12 and the inner wall of the casing assembly; when the low-speed gear ring gear 2 is limited and fixed, the plurality of shift steel balls A pair of straight grooves 13 abut against the inner wall of the casing assembly.

In this embodiment, the specific installation space is between the casing 3 and the high-speed gear ring gear 1 and the low-speed gear ring gear 2, and this installation space is located in the above-mentioned annular space; when the automatic two-speed torque wrench is started and used At this time, the reaction arm 6 on the reaction arm sleeve 4 is fixed to balance the output torque force. At this time, the torque resistance of the screw nut is low. The steel balls 11 are pushed to the shift oblique grooves 12 of the high-speed gear ring gear 1 one by one, and the high-speed gear ring gear 1 is limited and fixed by the limit grooves 17 opened on the inner wall of the reaction arm casing 4, and the low-speed gear ring gear 2 is in the position. The low-speed ring gear 2 does not participate in the speed ratio conversion, and the high-speed ring gear 1 and the high-speed adjustment part are converted to obtain a relatively low speed ratio. At this time, the power output part outputs a relatively high speed, resulting in The torque is relatively small, which can quickly fasten the screw nuts in the early stage; when the screw nuts are tightened in the last few turns, the resistance generated on the power output part increases significantly, and the high-speed gear ring gear is made under the reaction force. 1. When the torque increases, the shift oblique groove 12 on the outer circumference of the high-speed gear ring gear 1 drives the shift steel ball 11 to move into the corresponding straight groove 13 on the low-speed gear ring gear 2 after overcoming the resistance of the spring 10, using the reaction arm sleeve The limit groove 17 on the inner wall of the shell 4 is limited and fixed (this time is the preset torque value in the above), the high-speed ring gear 1 is in a state of following rotation without force, the high-speed ring gear 1 does not participate in the speed ratio conversion, and the low speed The gear ring 2 and the low-speed adjustment part are converted to obtain a relatively high speed ratio. At this time, the power output part outputs a relatively low speed and generates a relatively large torque, which can provide sufficient tightening between the screws and nuts. After the screw nut is tightened, the power output part is disconnected from the screw nut. At this time, the torque on the power output part is obviously reduced, and the shaft on the shifting steel ball 11 is The thrust force is obviously smaller than the elastic force of the spring 10, so that the spring 10 pushes the shift return ring 9 to drive the shift steel ball 11 to move in the opposite direction and back into the corresponding shift chute 12; specifically, in this embodiment, the straight groove The number of 13 and the shifting chute 12 is multiple times the number of shifting steel balls 11, so that the automatic two-speed torque wrench is more stable and fast in the two-stage conversion between high and low speeds.

With reference to FIG. 2 , each shift chute 12 adopted based on the above solution is a first notch groove, the notch of the first notch groove is arranged toward the low-speed gear ring gear 2 and the first notch groove extends from the width of one end of the notch to the other end. slowing shrieking.

The shift chute 12 is defined based on the above-mentioned structure, so that an inclined inner wall guiding the shift steel ball 11 is formed therein. To increase the torque on the high-speed ring gear 1, the shift steel ball 11 in the shift chute 12 generates an axial component force toward the spring 10 for the shift steel ball 11 through the inclined inner wall of the shift chute 12. , the axial component force is the above-mentioned axial thrust, so as to advantageously push the shift steel balls 11 into the corresponding straight grooves 13 to limit and fix the low-speed gear ring gear 2; in this embodiment, the first The notch groove is triangular, and the inner wall of the first notch groove for guiding the shifting steel ball 11 can be formed by connecting a plurality of side inner walls with different inclination angles.

At the same time, based on the above solution, each straight groove 13 used is a second notch groove, the notch of the second notch groove is arranged toward the high-speed gear ring gear 1, and the width of the second notch groove gradually increases from one end of the notch to the other end. big.

In this embodiment, the second notch groove is in the shape of an isosceles trapezoid, so as to limit the position of the introduced shifting steel ball 11 , so as to limit and fix the low gear ring gear 2 .

As shown in FIG. 1, according to another embodiment of the present invention, in the automatic two-speed torque wrench, the power input portion may be a power input shaft tooth 14, and one end of the power input shaft tooth 14 is driven by a motor. It is driven to rotate, the other end is provided with a ring gear and the ring gear freely passes through the casing 3 and then penetrates into the force arm sleeve to engage with the power transmission part, that is, mesh with the three planetary gears 8 in the power transmission part for transmission.

In order to improve the stability of the power input shaft tooth 14 during the rotation process, a bearing fixedly embedded in one end of the planet carrier 7 is provided on the inner outer fixed sleeve.

Based on the above solution, the adopted power output part includes a ring gear segment 15 meshed on the outside of the power transmission part and a power output shaft 16 connected to the ring gear segment 15. The inside of the shell 4 is freely penetrated; specifically, the ring gear segment 15 is meshed with the outside of the three planetary gears 8 in the power transmission part; The shaft tooth ends are matched to form a planetary gear structure. When the middle sun gear, planetary gear and ring gear in the planetary gear structure are not fixed, the power cannot be transmitted. 2 or the high-speed ring gear 1 is limited and fixed, so that power is transmitted from the ring gear segment 15 to drive the power output shaft 16 to rotate, and the power output shaft 16 can be connected by splines or square heads. , when the power output shaft 16 rotates to drive the sleeve to rotate, so that the nut or the screw is rotated to fasten the nut and the screw.

Due to the size design of the planetary gear 8 in the power transmission part, the low-speed adjustment part and the high-speed adjustment part, the inner diameter and the number of gear teeth corresponding to the ring gear segment 15, the low-speed ring gear 2 and the high-speed ring gear 1 are decreased in turn. .

Set the number of teeth of the high-speed ring gear 1 as a, the number of teeth of the planetary gear 8 in the high-speed adjustment part as b, the number of teeth of the low-speed ring gear 2 as c, and the number of teeth of the planetary gear 8 in the low-speed adjustment part is d, the number of teeth of the ring gear segment 15 is e, the number of teeth of the planetary gear 8 in the power transmission part is f, and the number of teeth of the shaft tooth end of the power input shaft tooth 14 is g.

When the high-speed ring gear 1 is limited and fixed, the calculation formula of the output speed ratio of the power take-off shaft 16 is:

When the limit of the low gear ring gear 2 is fixed, the calculation formula of the output speed ratio of the power take-off shaft 16 is:

Generally in design and use, when the high-speed gear ring gear 1 is limited and fixed, the output speed ratio of the power output shaft 16 reaches several tens; and when the low-speed gear ring gear 2 is limited and fixed, the output speed ratio of the power output shaft 16 reaches Hundreds to meet the actual use needs.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should The technical solutions are modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and all of them should be included in the scope of the claims of the present invention.

Claims (9)

1. an automatic two-speed torque wrench, is characterized in that, comprises: Chassis assembly; A multi-planetary gear assembly, the multi-planetary gear assembly is rotatably arranged in the casing assembly and includes a connected power transmission part, a low-speed gear adjustment part and a high-speed gear adjustment part; a power input part, one end of the power input part extends into the casing assembly and engages with the power transmission part for transmission; a power output part, one end of the power output part extends into the casing assembly and engages with the power transmission part for transmission; a high-speed gear ring gear, the high-speed gear ring gear is rotatably arranged in the casing assembly and meshes with the high-speed gear adjusting part; a low-speed gear ring gear, the low-speed gear ring gear is rotatably arranged in the casing assembly and meshes with the low-speed gear adjusting part; a gear adjustment component, the gear adjustment component cooperates with the casing assembly to change the limit fixation of the high-speed ring gear or the low-speed ring gear by a preset torque value; When in use, the casing assembly is fixed to transmit torque; and when the high-speed ring gear is limited and fixed, the output speed ratio on the power output part is smaller than the output speed ratio on the power output part when the low-speed ring gear is limited and fixed. 2. An automatic two-speed torque wrench according to claim 1, characterized in that: the multi-planetary gear assembly further comprises a planetary carrier rotatably arranged in the casing assembly, a power transmission part, a low-speed gear adjustment part And the high-speed adjustment part is rotatably arranged inside and outside the planet carrier from bottom to top, and the power transmission part, the low-speed adjustment part and the high-speed adjustment part all include a plurality of planets arranged circumferentially and rotatably penetrated inside and outside the planet carrier The gears, the power transmission part, the low-speed adjustment part and the multiple planetary gears in the high-speed adjustment part are connected in one-to-one correspondence in the vertical direction as a whole, and the number of teeth of the planetary gears in the power transmission part and the planetary gears in the low-speed adjustment part The number of teeth of the gear and the number of teeth of the planetary gears in the high-speed adjustment part decrease in turn, the multiple planetary gears of the power transmission part mesh with the outside of one end of the power input part and the inside of one end of the power output part, and the multiple planetary gears of the low-speed adjustment part The plurality of planetary gears of the high-speed adjusting part are meshed with the inner side of the high-speed ring gear. 3 . The automatic two-speed torque wrench according to claim 1 , wherein an installation space is formed between the casing assembly and the high-speed gear ring gear and the low-speed gear ring gear, and the gear adjustment assembly includes a sliding setting. 4 . In the shift return ring in the installation space, one end of the shift return ring is connected with the inner wall of the installation space through a spring, and the other end of the shift return ring is provided with a plurality of installation holes along its circumferential direction. Gear shift steel balls are rotatably arranged in the mounting holes, the outer wall of the high-speed gear ring gear is provided with a plurality of shifting oblique grooves along its circumferential direction, and the outer wall of the low-speed gear ring gear is provided with a plurality of straight concave grooves along its circumferential direction. The number of grooves, shift inclined grooves and straight grooves is not less than the number of shift steel balls; when the high-speed gear ring gear is limited and fixed, a plurality of shift steel balls are in a one-to-one correspondence with a plurality of shift inclined grooves Between the inner wall of the casing assembly; when the low-speed gear ring gear is limited and fixed, the plurality of shifting steel balls abut between the plurality of straight grooves and the inner wall of the casing assembly in a one-to-one correspondence. 4 . The automatic two-speed torque wrench according to claim 3 , wherein each of the shifting oblique grooves is a first notch groove, and the notch of the first notch groove is arranged toward the low-speed gear ring gear and the first notch groove is arranged. 5 . The width of a notch groove gradually decreases from one end of the notch to the other end. 5 . The automatic two-speed torque wrench according to claim 3 , wherein each of the straight grooves is a second notch groove, and the notch of the second notch groove is arranged toward the high-speed ring gear and the second notch. 6 . The width of the notch groove gradually increases from one end of the notch to the other end. 6. An automatic two-speed torque wrench according to claim 1, characterized in that: the casing assembly comprises a casing and a reaction arm sleeve, one end of which is inserted into the casing and rotatably connected, and the power output One end of the power input part away from the power transmission part freely passes through the reaction arm casing, and one end of the power input part freely passes through the casing and then penetrates into the force arm casing to engage with the power transmission part. 7 . The automatic two-speed torque wrench according to claim 6 , wherein the power output part comprises a ring gear segment engaged on the outside of the power transmission part and a power output shaft connected with the ring gear segment, and the power output The end of the shaft away from the ring gear segment freely protrudes from the reaction arm sleeve. 8 . The automatic two-speed torque wrench according to claim 6 , wherein the casing assembly further comprises a reaction arm fixedly connected to the outer wall of the reaction arm sleeve. 9 . 9 . The automatic two-speed torque wrench according to claim 3 , wherein the number of the shifting inclined grooves and the straight grooves is multiple times the number of the shifting steel balls. 10 .

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