CN219866096U - Bidirectional rotation electric tool transmission mechanism and electric tool - Google Patents

Abstract

The utility model relates to the field of electric tools, in particular to a bidirectional rotary electric tool transmission mechanism and an electric tool, which solve the problem that the electric tool with a rotary working part is difficult to control. The transmission mechanism comprises an inner shaft, an outer shaft, an inner rotary table, an outer rotary table, a transmission gear and a turning gear, wherein the inner shaft comprises a first gear part, and the outer shaft comprises a second gear part; the transmission gear is meshed with the first gear part to drive the inner shaft to rotate in a first direction, and is meshed with the second gear part to drive the outer shaft to rotate in a second direction through the turning gear; or the transmission gear is meshed with the first gear part through the turning gear to drive the inner shaft to rotate along the first direction, and is meshed with the second gear part to drive the outer shaft to rotate along the second direction; the rotation direction of the first direction is opposite to the rotation direction of the second direction; the transmission ratio between the transmission gear and the first gear portion is smaller than the transmission ratio between the transmission gear and the second gear portion.

Description

Bidirectional rotation electric tool transmission mechanism and electric tool

Technical Field

The utility model relates to the field of electric tools, in particular to an electric tool adopting a bidirectional rotary electric tool transmission mechanism.

Background

A power tool is a tool that can convert electric energy into mechanical energy, and generally uses an electric motor as a power source. Compared with the traditional manual tool, the electric tool has the advantages of high efficiency, accuracy, labor saving and the like, and can greatly improve the efficiency and quality of production work, thereby freeing the productivity. The electric tool can lighten the physical burden of people, accelerate the working process and improve the productivity.

Electric tools, such as a cleaning brush, a polisher, etc., for cleaning or polishing a surface of a workpiece or an object by rotating a working member are widely used in many industries, and work efficiency of people is improved.

The working member of the existing washing brush or polisher tends to rotate in one direction. Due to conservation of angular momentum, the working member of the brush or sander rotates in one direction, which results in a rotational force that rotates in the opposite direction on the brush or sander body. In addition, when the cleaning part of the cleaning brush or the polishing part of the polishing machine rotates to work, circumferential force is generated by friction with the working contact surface, and when the circumferential force of the cleaning part or the polishing part is balanced, lateral movement does not occur. However, in the actual use process, an operator often needs to move the cleaning brush or the polishing machine back and forth, and in the moving process, the cleaning part or the polishing part and the working contact surface may generate an inclination angle, so that the circumferential stress of the cleaning part or the polishing part is unbalanced, or the circumferential stress of the cleaning part or the polishing part is unbalanced due to the uneven working contact surface, so that the cleaning part or the polishing part and the working contact surface generate a lateral thrust, and a trend of lateral displacement of the cleaning brush or the polishing machine occurs. The superposition of the two forces can make the cleaning brush and the polisher difficult to control, and an operator needs to grasp the direction with force, so that the operator is easy to fatigue.

Disclosure of Invention

The utility model aims to solve the technical problems of overcoming the defects of the prior art and providing a bidirectional rotary electric tool transmission mechanism and an electric tool, so as to solve the technical problems that the electric tool with a rotary working part is difficult to control during working.

In order to achieve the technical aim, the utility model provides a bidirectional rotary electric tool transmission mechanism, which comprises an inner shaft, an outer shaft, an inner rotating disc driven by the inner shaft to rotate, an outer rotating disc driven by the outer shaft to rotate, a transmission gear and a turning gear, wherein the inner shaft comprises a first gear part, and the outer shaft comprises a second gear part;

the transmission gear is meshed with the first gear part for transmission so as to drive the inner shaft to rotate along a first direction, the transmission gear is meshed with the turning gear for transmission, and the turning gear is meshed with the second gear part for transmission so as to drive the outer shaft to rotate along a second direction;

or alternatively, the first and second heat exchangers may be,

the transmission gear is meshed with the turning gear, the turning gear is meshed with the first gear part transmission to drive the inner shaft to rotate in the second direction, and the transmission gear is meshed with the second gear part transmission to drive the outer shaft to rotate in the first direction;

the rotation direction of the first direction is opposite to the rotation direction of the second direction;

the transmission ratio between the transmission gear and the first gear portion is smaller than the transmission ratio between the transmission gear and the second gear portion.

Preferably, the rotation speed ratio of the outer shaft and the inner shaft is 1:1.5 to 1:5.

preferably, the transmission gear includes a double gear having an upper tooth portion and a lower tooth portion, the upper tooth portion engaging the first gear portion, and the lower tooth portion engaging the direction-changing gear.

Preferably, the front projection of the transmission gear and the direction changing gear on the inner rotary disk does not exceed the inner rotary disk.

Preferably, the inner shaft is detachably and fixedly connected to the inner turntable and coaxially rotates, and the outer shaft is detachably and fixedly connected to the outer turntable and coaxially rotates.

Preferably, the outer rotary disc is provided with an avoidance groove for accommodating the inner rotary disc.

Preferably, the bottom surface of the inner rotating disc is arranged flush with the bottom surface of the outer rotating disc.

The utility model also provides an electric tool, which comprises a shell, a motor, a bidirectional rotation transmission mechanism of the electric tool, wherein the motor is arranged in the shell, the bidirectional rotation transmission mechanism is driven by the motor, and working accessories are respectively arranged on the outer rotating disc and the inner rotating disc.

After the technical scheme is adopted, the utility model has the following beneficial effects.

1. The utility model provides a bidirectional rotary electric tool transmission mechanism, which comprises an inner shaft, an outer shaft, an inner rotary table, an outer rotary table, a transmission gear and a turning gear, wherein the inner shaft comprises a first gear part, the outer shaft comprises a second gear part, and the rotation directions of the inner shaft and the outer shaft are different through the turning gear; and the transmission ratio between the transmission gear and the first gear part is smaller than the transmission ratio between the transmission gear and the second gear part, so that the rotating speed of the inner shaft is larger than that of the outer shaft. First, through the change gear for interior axle and outer axle rotate along different directions, interior axle and outer axle can drive interior carousel and outer carousel and rotate along opposite directions, and the angular momentum that interior axle and outer axle respectively rotated and produce is opposite, can offset each other. And secondly, the inner rotary table and the outer rotary table rotate bidirectionally along opposite directions, when the cleaning part or the polishing part and the working contact surface generate an inclination angle or the working contact surface is uneven, opposite lateral forces generated by the respective rotation of the inner rotary table and the outer rotary table can be counteracted with each other as much as possible, so that the lateral thrust of the rotary table is reduced, the rotary table is not easy to generate displacement, and the control is easier. And thirdly, through the reverse rotation of the inner rotary table and the outer rotary table, bidirectional cleaning or polishing can be performed, the cleaning or polishing effect is improved, and the cleaned or polished grains are more uniform. And the rotation speed of the inner shaft is larger than that of the outer shaft, so that the lateral thrust and the angular momentum generated by the rotation of the inner rotating disc and the outer rotating disc can be offset as much as possible, and the cleaning brush or the polishing machine is easier to control.

2. The rotation speed ratio of the outer shaft to the inner shaft is 1:5-1:1.5, the outer shaft and the inner shaft can respectively drive the outer rotary disc and the inner rotary disc to rotate, and the outer rotary disc and the inner rotary disc have proper rotation speed ratios, so that opposite lateral forces generated by the respective rotation of the inner rotary disc and the outer rotary disc can be counteracted as much as possible.

3. The transmission gear is a duplex gear, and the upper tooth part and the lower tooth part of the transmission gear can have different tooth numbers, so that the tooth ratio of the transmission gear to the first gear part and the second gear part can be more conveniently adjusted, and the rotating speeds of the inner shaft and the outer shaft meet the requirement of the rotating speed ratio.

4. The bidirectional rotary transmission mechanism adopts a miniaturized design, the orthographic projection of the transmission gear and the direction-changing gear on the inner rotary table does not exceed the inner rotary table, the problem that the size of the transmission mechanism is too large to cause the corresponding generation of the overlarge volume of the electric tool is avoided, and the portability, the flexibility and the universality of the electric tool are improved on the basis of saving the material cost.

5. The inner shaft is detachably and fixedly connected with the inner turntable and coaxially rotates, and the outer shaft is detachably and fixedly connected with the outer turntable and coaxially rotates, so that the inner turntable and the outer turntable are more convenient to install and replace and maintain in the later period; the flexibility of the cleaning brush or the polisher is improved, and the proper inner rotating disc and the proper outer rotating disc can be replaced to meet the working requirement; in addition, the rotating shaft drives the turntable to connect in compact and stable mode, and this is favorable to raising the work efficiency of the inner and outer turntable.

6. The center part of outer carousel sets up the groove of dodging that is used for holding interior carousel, and interior carousel can install in the groove of dodging of outer carousel promptly, dodges the inner rotating disk through dodging the groove, can reduce the installation difference in height between inner carousel and the outer carousel to can reduce the difference in height between two clean annex that drive by inner rotating disk and outer carousel respectively, guarantee the effective scrubbing scope of cleaning brush, be favorable to improving the cleaning performance.

7. The bottom surface of interior carousel flushes the setting with the bottom surface of outer carousel to make the working face of the cleaning part or the portion of polishing that are driven respectively by interior carousel and outer carousel also can flush the setting, guarantee the operation effect of cleaning part or the portion of polishing when wasing or polishing, in addition, the counter side force that the rotation produced of balance carousel and outer carousel each that also can be better.

8. The electric tool provided by the utility model adopts the bidirectional rotary electric tool transmission mechanism, so that the electric tool has all the technical effects of the bidirectional rotary electric tool transmission mechanism.

Drawings

FIG. 1 is a schematic diagram of a bi-directional rotary power tool transmission mechanism according to an embodiment of the present utility model;

fig. 2 is a schematic cross-sectional view of a bi-directional rotary power tool transmission mechanism according to an embodiment of the utility model.

Reference numerals:

110. an outer shaft, 111, a second gear portion, 120, an inner shaft, 121, a first gear portion;

210. a transmission gear 211, an upper tooth part 212, a lower tooth part 220 and a turning gear;

300. the outer turntable, 301, avoiding the groove;

400. an inner turntable.

Detailed Description

The utility model provides a bidirectional rotary electric tool transmission mechanism, which comprises an inner shaft 120, an outer shaft 110, an inner rotating disc 400 driven by the inner shaft 120 to rotate, an outer rotating disc 300 driven by the outer shaft 110 to rotate, a transmission gear 210 and a turning gear 220, wherein the inner shaft 120 comprises a first gear part 121, and the outer shaft 110 comprises a second gear part 111; the transmission gear 210 is engaged with the first gear part 121 to transmit to drive the inner shaft 120 to rotate in the first direction, and the transmission gear 210 is engaged with the second gear part 111 through the direction-changing gear 220 to transmit to drive the outer shaft 110 to rotate in the second direction;

or alternatively, the first and second heat exchangers may be,

the transmission gear 210 is engaged with the first gear part 121 through the direction change gear 220 to transmit to drive the inner shaft 120 to rotate in the first direction, and the transmission gear 210 is engaged with the second gear part 111 to transmit to drive the outer shaft 110 to rotate in the second direction;

the rotation direction of the first direction is opposite to the rotation direction of the second direction;

the transmission ratio between the transmission gear 210 and the first gear part 121 is smaller than the transmission ratio between the transmission gear 210 and the second gear part 111.

The technical solutions of the embodiments of the present utility model will be explained and illustrated below with reference to the drawings of the embodiments of the present utility model, but the following embodiments are only preferred embodiments of the present utility model, and not all embodiments. Based on the examples in the implementation manner, other examples obtained by a person skilled in the art without making creative efforts fall within the protection scope of the present utility model.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present utility model, unless otherwise indicated, the meaning of "a plurality", "a number" or "a plurality" is two or more, unless otherwise clearly defined.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

As shown in fig. 1 and 2, a bi-directional rotary power tool transmission mechanism according to an embodiment of the present utility model includes an inner shaft 120, an outer shaft 110, an inner rotary plate 400, an outer rotary plate 300, a transmission gear 210, and a direction-changing gear 220. The power tool includes a motor that rotates to drive the drive gear 210. The inner shaft 120 includes a first gear portion 121, the outer shaft 110 includes a second gear portion 111, the transfer gear 210 engages the first gear portion 121 to drive the inner shaft 120 to rotate in a first direction, the transfer gear 210 engages the direction change gear 220 to drive the direction change gear 220 to rotate in the first direction, and the direction change gear 220 engages the second gear portion 111 to drive the outer shaft 110 to rotate in a second direction. The inner shaft 120 drives the inner rotary disc 400 to rotate, and the outer shaft 110 drives the outer rotary disc 300 to rotate, so that the inner rotary disc 400 and the outer rotary disc 300 rotate in different directions to realize bidirectional rotation. The first direction may be forward rotation or reverse rotation, and the second direction is opposite to the first direction.

It is understood that the transmission gear 210 may be directly fixed on the motor shaft, and the motor directly drives the transmission gear 210 to rotate, and the motor may also drive the transmission gear 210 to rotate through other speed reducing and transmission mechanisms. The motor drives the transmission gear 210 to rotate through other speed reducing mechanisms, a larger transmission ratio can be provided between the motor and the transmission gear 210, and correspondingly, the motor can be a high-speed motor, so that the motor has the advantages of small size, stability, high stability, low noise, low vibration, high response speed, high reliability and the like.

In other embodiments, the rotation direction of the first gear portion 121 may be changed by the change gear 220 to achieve rotation of the inner shaft 120 and the outer shaft 110 in different directions. Exemplary: the transmission gear 210 is meshed with the direction changing gear 220 to drive the direction changing gear 220 to rotate in a first direction, the direction changing gear 220 is meshed with the first gear part 121 to drive the inner shaft 120 to rotate in a second direction, the transmission gear 210 is meshed with the second gear part 111 to drive the outer shaft 110 to rotate in the first direction, and the inner shaft 120 and the outer shaft 110 rotate in different directions to realize bidirectional rotation.

It is understood that the first gear portion 121 may be integrally formed on the inner shaft 120, or may be a separate gear fixed to or sleeved on the inner shaft 120. Similarly, the second gear portion 111 may be integrally formed with the outer shaft 110, or may be fixed to the outer shaft 110 by a separate gear.

The inner shaft 120 is detachably and fixedly connected with the inner rotating disc 400 and coaxially rotates, the outer shaft 110 is detachably and fixedly connected with the outer rotating disc 300 and coaxially rotates, the inner shaft 120 drives the inner rotating disc 400 to rotate along a first direction, the outer shaft 110 drives the outer rotating disc 300 to rotate along a second direction, and the inner rotating disc 400 and the outer rotating disc 300 reversely rotate along different directions to realize bidirectional rotation of the inner rotating disc 400 and the outer rotating disc 300. The inner 400 and outer 300 rotatable disks may have cleaning or sanding attachments mounted thereon. When the inclination angle or the unevenness of the working contact surface is generated between the cleaning or polishing accessory and the working contact surface, the opposite lateral forces generated by the rotation of the inner rotating disc 400 and the outer rotating disc 300 can be counteracted as much as possible, so that the lateral thrust of the rotating disc is reduced, the rotating disc is not easy to displace, and the control is easier. And the inner rotating disc 400 and the outer rotating disc 300 rotate along different directions, and the angular momentum generated by the rotation of the inner rotating disc 400 and the outer rotating disc 300 are opposite and can be offset as much as possible.

However, since the outer turntable 300 has a larger diameter than the inner turntable 400, if the rotational speed of the inner turntable 400 is close to that of the outer turntable 300, the lateral force generated by the rotation of the outer turntable 300 is larger than that generated by the rotation of the inner turntable 400, and the angular momentum of the rotation of the outer turntable 300 is also larger than that of the rotation of the inner turntable 400, so that the outer turntable 300 and the inner turntable 400 generate a tendency of lateral displacement and rotation even if they rotate bidirectionally. It is necessary to increase the rotation speed of the inner turntable 400 or to decrease the rotation speed of the outer turntable 300 so that the two are balanced.

Since the change gear 220 does not change the transmission ratio, in order to make opposite lateral forces and angular momentums generated by the respective rotations of the outer dial 300 and the inner dial 400 approach each other as much as possible and thus cancel each other as much as possible, the bi-directional rotation transmission mechanism of the electric tool may be configured such that the transmission ratio between the transmission gear 210 and the first gear portion 121 is larger than the transmission ratio between the transmission gear 210 and the second gear portion 111, so that the rotation speed of the inner shaft 120 is larger than the rotation speed of the outer shaft 110.

However, if the rotation speed ratio of the outer turntable 300 to the inner turntable 400 exceeds a reasonable range, that is, if the rotation speed of the inner turntable 400 is not fast enough or fast enough, the optimal state still cannot be achieved, that is, the turntable still has a tendency of moving laterally and rotating, so that the rotation speed ratio of the outer turntable 300 to the inner turntable 400 needs to be set within a proper interval range. The rotation speed ratio of the outer rotary disk 300 to the inner rotary disk 400 is required to be determined according to the outer diameter ratio of the outer rotary disk 300 to the inner rotary disk 400, the difference in material density and thickness, etc. Preferably, the ratio of rotation of outer rotor 300 to inner rotor 400 ranges from 1:1.5 to 1:5; more preferably, the speed ratio ranges from 1:1.8 to 1:4; more preferably, the speed ratio ranges from 1:2 to 1:3.

The purpose of adjusting the rotation speed ratio of the outer dial 300 and the inner dial 400 may be achieved by providing the first gear portion 121 and the second gear portion 111 with different numbers of teeth. The transmission gear 210 may be configured as a double gear, and different teeth of the transmission gear 210 respectively engage with the first gear portion 121 and the second gear portion 111, so as to achieve the purpose of adjusting the rotation speed ratio of the outer rotary disc 300 and the inner rotary disc 400.

Preferably, the transmission gear 210 is a double gear including an upper tooth portion 211 and a lower tooth portion 212. Wherein the direction change gear 220 is engaged with the second gear portion 111. The upper tooth portion 211 engages the first gear portion 121 to drive the first gear portion 121 to rotate in a first direction, the lower tooth portion 212 engages the direction change gear 220 to drive the first gear portion 121 to rotate in the first direction, and the direction change gear 220 engages the second gear portion 111 to drive the second gear portion 111 to rotate in a second direction. The upper tooth portion 211 and the lower tooth portion 212 of the driving gear 210 may have two different tooth numbers through the duplex gear, so as to more conveniently adjust the gear ratio of the driving gear 210 to the first gear portion 121 and the second gear portion 111 to meet the requirement of the rotation speed ratio of the outer rotary disc 300 and the inner rotary disc 400.

In this embodiment, in order to avoid that the external size of the electric tool is affected by the oversized transmission mechanism, and thus the portability, flexibility and versatility of the electric tool are affected, the transmission mechanism is preferably designed to be miniaturized. Specifically, the front projection of the transmission gear 210 and the direction changing gear 220 on the outer rotary plate 300 does not exceed the outer rotary plate 300; more preferably, the front projection of the drive gear 210 and the direction change gear 220 on the inner dial 400 does not exceed the inner dial 400.

As shown in fig. 1 and fig. 2, unlike the foregoing embodiment, the driving mechanism for a bi-directional rotary electric tool according to the present utility model is provided with the avoidance groove 301 for accommodating the inner rotary disk 400 in the outer rotary disk 300, that is, the inner rotary disk 400 may be installed in the avoidance groove 301 of the outer rotary disk 300, and the avoidance groove 301 is used for avoiding the inner rotary disk 400, so as to reduce the installation height difference between the inner rotary disk 400 and the outer rotary disk 300, and avoid that after the cleaning portion or the polishing portion is installed on the outer rotary disk 300 and the inner rotary disk 400, respectively, the height difference between the inner cleaning portion and the outer cleaning portion or the polishing portion is formed, thereby causing that a certain cleaning portion or polishing portion cannot work normally.

In this embodiment, preferably, the bottom surface of the inner rotating disc 400 is flush with the bottom surface of the outer rotating disc 300, so that the working surfaces of the cleaning part or the polishing part driven by the inner rotating disc 400 and the outer rotating disc 300 respectively can be flush, the working effect of the cleaning part or the polishing part during cleaning or polishing is ensured, and in addition, the opposite lateral forces generated by the respective rotation of the inner rotating disc 400 and the outer rotating disc 300 can be balanced better.

In other embodiments, a sliding structure is disposed between the avoidance groove 301 and the inner rotating disc 400, so that the inner rotating disc 400 can be better positioned in the avoidance groove 301 to avoid the inner rotating disc 400 from shaking relative to the outer rotating disc 300 during working, and meanwhile, the friction force of the inner rotating disc 400 is smaller when rotating relative to the outer rotating disc 300. The sliding structure may be a ball, a roller or a rolling bearing, etc. disposed on the inner turntable 400 and/or the avoiding groove 301, and when the transmission mechanism works, the surface of the inner turntable 400 and/or the inner wall of the avoiding groove 301 slides relative to the ball, the roller or the rolling bearing, and the ball, the roller or the rolling bearing rotates or rolls relative to the inner turntable 400 and/or the avoiding groove 301.

In one embodiment of the present utility model, an electric tool is provided, which includes a casing, a motor, and the motor is disposed in the casing, the electric tool adopts a bi-directional rotation electric tool transmission mechanism described in any of the foregoing embodiments, the motor drives the transmission mechanism, and working accessories are respectively mounted on the outer rotating disc 300 and the inner rotating disc 400.

Illustratively, the power tool is a sander, and sanding accessories are mounted on the outer and inner rotating discs 300, 400, respectively. The sanding accessory may be a sanding sheet, a polishing sheet, a sponge sheet, a wool felt, or the like.

Illustratively, the electric tool is a cleaning brush, and cleaning attachments are respectively mounted on the outer rotor 300 and the inner rotor 400 of the cleaning brush. The cleaning accessory can be a brush, a sponge brush, a scouring pad and the like.

It will be appreciated that the power tool is not limited to a sander and a cleaning brush, and that the power tool may be other power tool bodies having a bi-directional rotating working structure.

While the utility model has been described in terms of embodiments, it will be appreciated by those skilled in the art that the utility model is not limited thereto but rather includes the drawings and the description of the embodiments above. Any modifications which do not depart from the functional and structural principles of the present utility model are intended to be included within the scope of the appended claims.

Claims (8)

1. The electric tool transmission mechanism capable of rotating bidirectionally is characterized by comprising an inner shaft, an outer shaft, an inner rotating disc driven by the inner shaft to rotate, an outer rotating disc driven by the outer shaft to rotate, a transmission gear and a turning gear, wherein the inner shaft comprises a first gear part, and the outer shaft comprises a second gear part;

the transmission gear is meshed with the first gear part for transmission so as to drive the inner shaft to rotate along a first direction, the transmission gear is meshed with the turning gear for transmission, and the turning gear is meshed with the second gear part for transmission so as to drive the outer shaft to rotate along a second direction;

or alternatively, the first and second heat exchangers may be,

the transmission gear is meshed with the turning gear, the turning gear is meshed with the first gear part transmission to drive the inner shaft to rotate in the second direction, and the transmission gear is meshed with the second gear part transmission to drive the outer shaft to rotate in the first direction;

the rotation direction of the first direction is opposite to the rotation direction of the second direction;

the transmission ratio between the transmission gear and the first gear portion is smaller than the transmission ratio between the transmission gear and the second gear portion.

2. The bi-directional rotating power tool transmission according to claim 1, wherein the rotation speed ratio of said outer shaft and said inner shaft is 1:1.5 to 1:5.

3. a bi-directional rotary power tool transmission according to claim 1, wherein said transmission gear comprises a double gear having an upper toothed portion and a lower toothed portion, said upper toothed portion engaging said first gear portion and said lower toothed portion engaging said change gear.

4. A bi-directional rotary power tool transmission according to claim 1, wherein the front projection of said drive gear and said change gear on said inner rotatable disc does not exceed said inner rotatable disc.

5. The bi-directional rotary power tool transmission mechanism of claim 1, wherein said inner shaft is detachably fixedly connected to said inner rotary disc and rotates coaxially, and said outer shaft is detachably fixedly connected to said outer rotary disc and rotates coaxially.

6. The bi-directional rotary power tool transmission mechanism of claim 5, wherein said outer rotary plate has a relief groove therein for receiving said inner rotary plate.

7. The bi-directional rotary power tool transmission mechanism of claim 5, wherein the bottom surface of said inner rotatable plate is flush with the bottom surface of said outer rotatable plate.

8. The electric tool comprises a casing and a motor, wherein the motor is arranged in the casing, and the electric tool is characterized by comprising the bidirectional rotary electric tool transmission mechanism as claimed in any one of claims 1 to 7, the motor drives the bidirectional rotary transmission mechanism, and working accessories are respectively arranged on the outer rotary disc and the inner rotary disc.