CN217422064U

CN217422064U - Transmission mechanism and power tool with same

Info

Publication number: CN217422064U
Application number: CN202220258118.4U
Authority: CN
Inventors: 胡涛; 张清锋; 麻立国
Original assignee: Techtronic Cordless GP
Current assignee: Techtronic Cordless GP
Priority date: 2022-02-08
Filing date: 2022-02-08
Publication date: 2022-09-13
Anticipated expiration: 2032-02-08
Also published as: DE102022117690A1

Abstract

The utility model provides a drive mechanism and have its power tool. The transmission mechanism includes a housing, a gear unit provided in the housing, a switching member, and a lock ring. The switch member is axially movable between a locked position, which is held fixed relative to the housing, and an unlocked position, which is rotatable with the gear unit, to change the rotational speed. The housing is provided with a mounting groove in a circumferential direction perpendicular to the rotation axis, and the lock ring is inserted into the housing through the mounting groove and non-rotatably mounted, and is engageable with the switch member in the lock position to fix it. According to the utility model discloses a scheme, the casing is integrative component, has higher intensity. The axial thickness of the locking ring is small, and the axial size of the whole transmission mechanism is shortened. The locking ring is bigger with adjacent spare part area of contact in the axial, and contact strength is high, and the location effect is better. In addition, the manufacturing process of the locking ring is simple, the number of parts of the transmission mechanism is reduced, the assembly steps can be simplified, and the cost is reduced.

Description

Transmission mechanism and power tool with same

Technical Field

The utility model relates to a power tool's technical field, more specifically relate to a drive mechanism and have its power tool.

Background

The power tool can be applied to various everyday tasks such as drilling, screwing, etc. by outputting torque. While power tools are often provided with a transmission to achieve reliable control of the output speed. Such a transmission mechanism generally includes a plurality of gears and various components used in cooperation with the gears, and has a complicated structure and a large number of assembly steps. Also, since there are many parts, the failure rate increases. Resulting in increased manufacturing costs and shortened service life of the power tool. At the same time, miniature tools with compact structures are becoming increasingly popular.

Therefore, it is desirable to provide a transmission mechanism and a power tool having the same, so as to overcome the disadvantages of the conventional power tool.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a drive mechanism and have its power tool to improve among the current power tool more, the comparatively complicated problem of manufacturing and assembly of drive mechanism's spare part, thereby reduce manufacturing cost, increase life reduces the instrument size.

According to an aspect of the utility model, drive mechanism includes:

a housing;

a gear unit provided in the housing for transmitting a driving force between an input shaft and an output shaft;

a switch provided in the housing and movable along a rotational axis of the gear unit between a locked position held fixed relative to the housing and an unlocked position rotatable with the gear unit to change a rotational speed of the output shaft, an

A lock ring provided with a mounting groove in a circumferential direction perpendicular to the rotation axis, the lock ring being inserted through the mounting groove and non-rotatably mounted on the housing and engageable with the switch in the lock position to fix the switch relative to the housing. And provides axial positioning for the next stage gear ring near the output end.

In some embodiments, the locking ring is configured in a C-shape.

In some embodiments, the housing has a first connection portion connecting its two portions on both axial sides of the mounting groove, and the locking ring is provided with an outwardly offset portion at a position diametrically opposite to the opening of the C-shape, the offset portion abutting on an outer side of the first connection portion in a mounted state of the locking ring.

In some embodiments, the housing is provided with two first protruding portions protruding outward in the radial direction with respect to the housing wall at both sides in the axial direction of the first connecting portion, and the offset portion is interposed between the two first protruding portions, and it is preferable that the circumferential direction and the side surface of the first protruding portion have the same size as those of the offset portion, and are fixed together by the tool housing.

In some embodiments, the housing has a second connecting portion connecting its two parts on both axial sides of the mounting groove, which second connecting portion is located in the opening of the C-shape in the mounted state of the locking ring.

In some embodiments, the housing is provided with two second protrusions protruding radially outward relative to the housing wall on both axial sides of the second connecting portion, the locking ring is provided with an opening protrusion protruding radially outward at an end portion forming a C-shaped opening, the opening protrusion is interposed between the two second protrusions, and preferably, the second connecting portion extends from the housing wall of the housing to an outer edge of the second protrusion in the radial direction, has the same outer circumferential dimension as the opening protrusion, and is fixed together by the tool housing.

In some embodiments, the housing has third protrusions provided at circumferential positions intersecting with a radial direction perpendicular to the insertion direction and located on both axial sides of the mounting groove, and third connecting portions connecting the two third protrusions, and it is preferable that the lock ring is formed as a straight edge at a circumferential position intersecting with the radial direction perpendicular to the insertion direction, and it is preferable that the straight edge is parallel to the insertion direction.

In some embodiments, the housing is provided with a plurality of protrusions spaced apart in the circumferential direction on both axial sides of the mounting groove and protruding outward in the radial direction of the rotation axis with respect to the housing wall, and preferably the housing has a connecting portion provided at substantially the same circumferential position as the protrusions, the connecting portion connecting both portions of the housing on both axial sides of the mounting groove, forming the housing as an integral member, and preferably the connecting portion extends in the radial direction within the range of the housing wall and/or the protrusions.

In some embodiments, the lock ring has a tooth portion protruding radially inward of the rotation axis from an inner surface of the housing, and the switch has a groove portion with which the tooth portion is engaged in the lock position. In the unlocking position, the tooth parts are disengaged from the groove parts, and preferably, the tooth parts are arranged in a plurality of numbers and are symmetrically distributed on the locking ring along the circumferential direction, so that the tooth parts are matched with the assembling characteristics of the locking ring and the engagement is not influenced.

In some embodiments, the gear unit includes a planetary gear train on a side of the lock ring facing away from the switch, the planetary gear train including an inner ring gear meshing with a plurality of planetary gears, the teeth of the lock ring abutting an axial end of the inner ring gear.

In some embodiments, the gear unit comprises at least one stage of planetary gear train, each stage of the at least one stage of planetary gear train comprising a sun gear and a plurality of planet gears meshing with the sun gear; wherein the switch has an inner tooth portion, and in the unlocked position, the inner tooth portion of the switch is simultaneously engaged with a sun gear of one planetary gear train and a plurality of planetary gears, and in the locked position, the inner tooth portion of the switch is disengaged from the sun gear of the one planetary gear train while remaining engaged with the plurality of planetary gears of the one planetary gear train.

In some embodiments, the sun gear has a large diameter tooth portion for meshing with the internal tooth portion and a small diameter tooth portion axially offset from the large diameter tooth portion and for meshing with a plurality of planetary gears of a planetary gear train of the same stage.

According to another aspect of the present invention, the power tool includes:

a motor having an input shaft for generating torque;

an output shaft for outputting torque to the outside; and

in the transmission mechanism, the gear unit is in transmission coupling with the input shaft and the output shaft respectively.

According to the technical scheme of the utility model, following beneficial effect can be realized:

the shell of the transmission mechanism is constructed into an integral component, so that the transmission mechanism has higher structural strength, more shells have better coaxiality, and the transmission mechanism is lower in cost. The switching piece is locked through the locking ring, the axial thickness of the switching piece is small, the overall structure is compact, and the axial size of the whole transmission mechanism is shortened. The locking ring can have a larger contact area with the part axially positioned by the locking ring, so that the strength is higher and the positioning effect is good. In addition, the locking ring can be manufactured by adopting a stamping process, the number of parts required by the transmission mechanism is reduced, the production cost can be reduced, and the assembly steps are simplified.

Drawings

For a better understanding of the above and other objects, features, advantages and functions of the invention, reference should be made to the preferred embodiments illustrated in the accompanying drawings. Like reference numerals in the drawings refer to like parts. It will be understood by those skilled in the art that the drawings are intended to illustrate a preferred embodiment of the invention without any limiting effect on the scope of the invention, and that the various components in the drawings are not to scale.

Fig. 1 is a perspective view of a transmission mechanism according to a preferred embodiment of the present invention;

fig. 2 is a sectional view taken along line a-a in fig. 1, in which the switch is in the locked position;

FIG. 3 is a sectional view taken along line B-B of FIG. 1;

fig. 4 is a perspective view of a switching member of the transmission mechanism shown in fig. 1;

fig. 5 is a sectional view of the transmission mechanism shown in fig. 1 along the rotational axis of the gear unit, with the housing omitted and the switch in the unlocked position;

FIGS. 6 and 7 are perspective views of the housing of the transmission shown in FIG. 1;

FIG. 8 is a sectional view taken along line C-C in FIG. 6; and

fig. 9 is a perspective view of a locking ring of the transmission mechanism shown in fig. 1.

Description of the reference numerals:

1 drive mechanism

2 output shaft

10 casing

101 mounting groove

102 through groove

11 first connection part

111 first projection

12 second connecting part

121 second projection

13 third connecting part

131 third projection

20 gear unit

21 first planetary gear train

22 second planetary gear train

23 third planetary gear train

30 switching piece

31 coupling groove

32 internal tooth part

33 groove part

34 chamfer

40 locking ring

41 tooth system

42 opening

43 offset part

44 straight edge

45 open convex part

50 change-over switch

51 coupling end

AX axis of rotation

D direction of insertion

Detailed Description

Referring now to the drawings, specific embodiments of the present invention will be described in detail. What has been described herein is merely a preferred embodiment in accordance with the present invention, and those skilled in the art will appreciate that other ways of implementing the present invention on the basis of the preferred embodiment will also fall within the scope of the present invention.

The utility model provides a power tool (not shown). The power tool may include a housing (not shown), a motor (not shown), a transmission mechanism, and an output shaft. Wherein the motor may be an electric motor or a pneumatic motor, etc., which may be enclosed in a housing, driven by a corresponding power source to generate torque. The motor may have a drive shaft and be drivingly coupled to the drive mechanism through the drive shaft. The transmission mechanism is also in transmission connection with the output shaft, and transmits the torque output by the motor to the output shaft after speed change, so as to output the torque to the outside. Some examples of power tools may be drills, impact wrenches, or the like.

Fig. 1 to 2 exemplarily show a transmission mechanism 1 for a power tool, which mainly includes a housing 10, a gear unit 20, a switch 30, and a lock ring 40. A gear unit 20 is provided in the housing 10, in driving engagement with the drive shaft of the motor and the output shaft 2 of the power tool, respectively. The drive shaft of the motor may also be referred to as input shaft with respect to the gear unit 20. The torque from the motor is changed to a speed suitable for performing a corresponding operation (e.g., drilling, tightening, etc.) after passing through the gear unit 20, and then transmitted to a corresponding front-end tool (e.g., a drill bit, a sleeve coupled with a fastener, etc.) coupled thereto via the output shaft 2.

The switch 30 is provided in the housing 10, is engaged with the gear of the gear unit 20, and is movable between a lock position (see fig. 2) and an unlock position (see fig. 3) along the rotation axis AX of the gear unit 20. In the lock position, the switch 30 is engaged with the lock ring 40, and the lock ring 40 is held against rotation about the rotation axis AX relative to the housing 10. In the unlocked position, the switch 30 is disengaged from the lock ring 40, so that the switch 30 can rotate with the gear unit 20 relative to the housing 10. By switching between the locked position and the unlocked position, the switching member 30 can change the transmission relationship of the gear unit 20, thereby changing the ratio of the gear change thereof, thereby further changing the rotation speed of the output shaft 2.

As shown in fig. 2 and 4, in some embodiments, the gear unit 20 may include a planetary gear train including a sun gear and a plurality of planet gears that are engaged, a mounting bracket for mounting the plurality of planet gears, and an inner gear ring engaged with the plurality of planet gears. Torque may be received through the sun gear and output outward through the planet gears, whereby the torque is changed in speed as it is transmitted from the sun gear to the planet gears.

Preferably, the switch 30 can be designed in the form of a ring with an internal toothing 32 arranged radially on the inside. The switching member 30 may be used as an inner gear ring of the planetary gear train. When the switch 30 is in the locked position, it is fixed relative to the housing 10 and meshes with the plurality of planetary gears. The planetary gear train transfers torque outwardly at the rotational speed of the plurality of planet gears. The output of the planetary gear train is in a low-speed high-torque state. When the switch 30 is located at the unlock position, it is engaged not only with the plurality of planetary gears but also with the sun gear, and can rotate together with the planetary gear train with respect to the housing 10. At this time, the plurality of planetary gears are fixed relative to the sun gear, and the planetary gear train no longer has a speed change function, but outputs the torque received by the sun gear in a non-speed change manner. The output of the planetary gear train is in a high-speed low-torque state. Thereby, the axial movement of the switch 30 between the locked position and the unlocked position changes the gear shift result of the gear unit 20, i.e. changes the rotational speed of the output shaft 2.

As shown in fig. 5, in some embodiments, the sun gear may have a large-diameter section and a small-diameter section arranged in the axial direction, wherein an outer side surface of the large-diameter section is provided with a large-diameter tooth portion for meshing with the internal tooth portion 32 of the switching member 30, and an outer side surface of the small-diameter section is provided with a small-diameter tooth portion for meshing with the plurality of planetary gears. When the switch 30 is located at the lock position, the inner teeth 32 thereof are engaged with only the plurality of planetary gears, and when the switch 30 is located at the unlock position, the inner teeth 32 thereof are simultaneously engaged with the large-diameter teeth of the sun gear and the plurality of planetary gears.

Preferably, the switch 30 is driven by the switch 50 to move axially between the locked and unlocked positions. As shown in fig. 1 and 5, a switch 50 is provided outside the housing 10, which has a coupling end 51. The housing 10 is provided with a through groove 102 extending in the axial direction. The coupling end 51 projects into the interior of the housing 10 through the through-slot 102. Accordingly, the outer side of the switch piece 30 is provided with a coupling groove 31 running circumferentially therearound. The coupling end 51 protrudes into the coupling groove 31. Thus, when the toggle switch 50 moves axially relative to the housing 10, the coupling end 51 thereof drives the switch member 30 to move axially relative to the housing 10 through the coupling groove 31. And when the switch 30 is located at the unlock position, the coupling groove 31 surrounding one circle allows the switch 30 to rotate together with the gear unit 20 without interference with the coupling end 51.

The locking ring 40 serves to keep the switch 30 fixed with respect to the housing 10 when it is located at the locking position, so that the switch 30 functions as an inner ring gear. As can be seen from fig. 3, 4 and 9, the lock ring 40 has a tooth portion 41 projecting radially inward from the inner surface of the housing 10, and accordingly, the outer peripheral side of the switch 30 toward the end of the lock ring 40 is provided with a groove portion 33. When the switch 30 is located at the lock position, the tooth portion 41 of the lock ring 40 engages with the groove portion 33 of the switch 30 to prevent the switch 30 from rotating relative to the housing 10 while abutting against the switch 30 to axially position it.

Preferably, the tooth portion 41 and/or the groove portion 33 are provided in plurality at intervals in the circumferential direction. Preferably, the circumferential dimension of the groove portion 33 is larger than the circumferential dimension of the tooth portion 41, and thus, the tooth portion 41 and the groove portion 33 can be more easily aligned to facilitate the engagement therebetween. It is further preferred that the axial end of the switch 30 facing the locking ring 40 is provided with a chamfer 34 to facilitate the insertion of this axial end of the switch 30 at least partially into the locking ring 40, thereby making the alignment of the teeth 41 and the grooves 33 easier.

Preferably, the gear unit 20 may include only one stage of planetary gear train, and may also include two or more stages of planetary gear trains. For example, as shown in fig. 2, the gear unit 20 includes a first planetary gear train 21, a second planetary gear train 22, and a third planetary gear train 23, which are sequentially drivingly coupled. The switching member 30 may function as an inner gear ring of one of the planetary gear trains. For example as a ring gear of the second planetary gear train 22. It is also preferable to provide a plurality of switching members as ring gears of different planetary gear trains, respectively, to achieve more various gear selection.

Preferably, a side of the lock ring 40 facing away from the switch 30 is provided with a next-stage planetary gear train. The tooth 41 of the lock ring 40 may abut against an axial end face of the ring gear of the next-stage planetary gear train for axially positioning the ring gear. In some embodiments, the next stage planetary gear train may be a third planetary gear train 23 coupled to the output shaft 2, which may also be referred to as an output planetary gear train 23.

According to the present invention, as shown in fig. 6 to 8, the housing 10 of the transmission mechanism 1 is constructed as an integral member having a mounting groove 101 extending along the circumferential direction. The locking ring 40 may be inserted into the housing 10 from the outside of the housing 10 through the mounting groove 101 and non-rotatably mounted on the housing 10. Preferably, as shown in fig. 9, in some embodiments, the locking ring 40 is configured in a C-shape, which may be formed by a manufacturing process such as stamping. When mounted, the C-shaped lock ring 40 can be inserted into the mounting groove 101 in the insertion direction D (see fig. 3) with the opening 42 of the C-shape at the front.

As shown in fig. 6 and 8, the housing 10 has a first connecting portion 11 located substantially in the thickness range of the housing wall in the radial direction, connecting portions of the housing 10 located on both sides in the axial direction of the mounting groove 101. Accordingly, the locking ring 40 is provided with a radially outwardly offset 43 at a location radially opposite the opening 43. The space inside the offset portion 43 may be complementary to the first connection portion 11. When the locking ring 40 is in place, its offset 43 abuts against the outside of the first connection 11. This arrangement ensures that the housing 10 has a unitary construction and can also be used to locate the locking ring 40.

Preferably, portions of the housing 10 located at both sides of the mounting groove 101 are provided with first protrusions 111 at substantially the same circumferential positions as the first connection portions 11, respectively. The first projection 111 projects radially outward with respect to the outer surface of the housing 10. As shown in fig. 1 and 3, when the locking ring 40 is installed in place, the offset 43 is sandwiched between the two first tabs 111.

Further, the housing 10 also has second connection portions 12 connecting both axial side portions thereof located in the mounting groove 101. When the locking ring 40 is in place, the second connecting portion 12 is located within the opening 42 of the locking ring 40. Similar to the first convex portion 111, portions of the housing 10 on both sides of the mounting groove 101 are also provided with second convex portions 121 at substantially the same circumferential positions as the second connecting portion 12, respectively. Also, since the lock ring 40 is the opening 42 at the circumferential position corresponding to the second connecting portion 12, the second connecting portion 12 is not only located within the thickness range of the housing wall but also expands radially outward to the outer side of the second protrusion 121. The first projection 111 and the second projection 121 on the one hand may increase the structural strength of the housing 10 and may also serve for positioning the locking ring 40 and, in addition, for positioning between the transmission 1 and the housing of the power tool.

Preferably, with reference to fig. 9, the locking ring 40 is provided with an opening lug 45 projecting radially outwards at the end forming the opening 42. The circumferential dimension of the second protrusions 121 is larger than the circumferential dimension of the second connection portion 12, whereby an accommodation space can be formed between the two second protrusions 121. The open tab 45 may be located in the receiving space when the locking ring 40 is in place. The provision of the split protrusion 45 increases the contact area of the lock ring 40 with the housing 10, thereby increasing the strength thereof and improving the deformation resistance.

Preferably, as shown in fig. 3 and 6 to 8, portions of the housing 10 on both sides in the axial direction of the mounting groove 101 are further provided with third protrusions 131 at circumferential positions intersecting with a radial direction perpendicular to the insertion direction D, and are further provided with third connecting portions 13 connecting the two third protrusions 131. In order to ensure that the lock ring 40 has a sufficient contact area with the side of the mounting groove 101 at this position and to facilitate the insertion-mounting of the lock ring 40, the third connecting portion 13 is provided only within the range of the third protrusion 131, and the housing walls of the housing 10 on both axial sides of the mounting groove 101 are separated by the mounting groove 101 at this position without direct connection. The third convex portion 131 may function substantially the same as the first convex portion 111 and the second convex portion 121.

Preferably, the first projection 111 is flush with the circumferential sides of both the offset portions 43, and/or the second projection 121 is flush with the circumferential sides of both the opening projections 45. Such an arrangement may allow the first protrusion 111 and the offset 43 to be simultaneously received and secured by the axially extending recess in the housing and/or the second protrusion 121 and the open protrusion 45 to be simultaneously received and secured by the axially extending recess in the housing when the transmission is disposed in the housing of the power tool.

Turning again to fig. 9, the locking ring 40 is preferably formed as a straight edge 44 at a circumferential position that intersects a radial direction perpendicular to the insertion direction D. As shown in fig. 8, the flat edge 44 requires less space than the locking ring 40 having a convex arcuate edge at this location, and therefore the radial dimension of the third connecting portion 13 can be increased, thereby further increasing the structural strength of the housing 10. In addition, the outer edge of the locking ring 40 may project radially outwardly relative to the outer surface of the housing 10 when the locking ring 40 is in place to increase the size of the locking ring 40 and improve its structural strength. Preferably, the inner side surface of the third connecting portion 13 is formed as a plane. The flat edge 44 may abut against the inner side of the third connecting portion 13 and prevent the locking ring 40 from rotating relative to the housing 10.

It is to be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only. However, in other embodiments of the transmission mechanism according to the present invention, the mounting groove, the connecting portion, the protrusion, the locking ring, and the like may have other configurations. For example, the locking ring may be designed as a closed ring, or may be designed as a plurality of separate segments. For example, the radial convex parts of the shell can be arranged in plurality at intervals, for example, four radial convex parts can be arranged along the extending direction of the mounting groove, and the plurality of radial convex parts can be uniformly distributed or non-uniformly distributed. The connection parts of the connection housing at both side portions of the mounting groove may or may not correspond to the radial protrusions. And when the connecting part corresponds to the radial convex part, the connecting part can be only connected with the radial convex parts at two sides of the mounting groove, can also be only connected with the shell walls at two sides of the mounting groove, and can also be simultaneously connected with the radial convex parts at two sides of the mounting groove and the shell walls. Those skilled in the art can flexibly select the specific implementation mode according to the needs.

The foregoing description of various embodiments of the invention is provided to one of ordinary skill in the relevant art for the purpose of illustration. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. As above, various alternatives and modifications of the present invention will be apparent to those of ordinary skill in the art. Thus, while some alternative embodiments are specifically described, other embodiments will be apparent to, or relatively easily developed by, those of ordinary skill in the art. The present invention is intended to embrace all such alternatives, modifications and variances of the present invention described herein, as well as other embodiments that fall within the spirit and scope of the present invention as described above.

Claims

1. A transmission mechanism, characterized in that it comprises:

a housing (10);

a gear unit (20), the gear unit (20) being provided in the housing (10) for transmitting a driving force between an input shaft and an output shaft (2);

a switch (30) that is provided in the housing (10), and that is movable along a rotational Axis (AX) of the gear unit (20) between a locked position that is held fixed relative to the housing (10) and an unlocked position that is rotatable with the gear unit (20) to change a rotational speed of the output shaft (2);

a lock ring (40), the housing (10) being provided with a mounting groove (101) in a circumferential direction perpendicular to the rotation Axis (AX), the lock ring (40) being inserted through the mounting groove (101) and non-rotatably mounted on the housing (10), and being engageable with the switch member (30) at the lock position to fix the switch member (30) relative to the housing (10).

2. Transmission mechanism according to claim 1, characterized in that the locking ring (40) is configured in a C-shape.

3. Transmission according to claim 2, characterized in that the housing (10) has a first connection (11) connecting its two parts on both axial sides of the mounting groove (101), the locking ring (40) being provided with an offset (43) which is offset radially outwards with respect to the axis of rotation (AX), the offset (43) abutting on the outside of the first connection (11) in the mounted state of the locking ring (40) keeping the locking ring (40) coaxial with the housing (10).

4. A transmission mechanism according to claim 3, wherein the housing (10) is provided with two first convex portions (111) protruding outward in the radial direction with respect to a housing wall at both axial sides of the first connecting portion (11), the offset portion (43) being sandwiched between the two first convex portions (111).

5. Transmission according to claim 4, characterized in that the circumferential dimension of the first protrusion (111) is not smaller than the circumferential dimension of the offset (43) and/or in that the circumferential sides of the first protrusion (111) are flush with the circumferential sides of the offset (43).

6. Transmission according to claim 2, characterized in that the housing (10) has a second connection portion (12) connecting its two parts on both axial sides of the mounting groove (101), which second connection portion (12) is located in the C-shaped opening (42) in the mounted state of the locking ring (40).

7. Transmission according to claim 6, characterized in that the housing (10) is provided with two second protrusions (121) at both axial sides of the second connection portion (12) projecting radially outwards with respect to the housing wall with respect to the axis of rotation (AX), the locking ring (40) being provided with an opening protrusion (45) projecting radially outwards at the end forming a C-shaped opening (42), the opening protrusion (45) being sandwiched between the two second protrusions (121).

8. Transmission according to claim 7, characterized in that the second connection portion (12) extends in the radial direction from a housing wall of the housing (10) to an outer edge of the second projection (121) and/or in that a circumferential side of the second projection (121) is flush with a circumferential side of the opening projection (45).

9. The transmission mechanism according to claim 1, wherein the housing (10) has third protrusions (131) provided at circumferential positions intersecting with a radial direction perpendicular to the insertion direction (D) and located on both sides in an axial direction of the mounting groove (101), and a third connecting portion (13) connecting the two third protrusions (131).

10. Transmission mechanism according to claim 9, characterized in that the locking ring (40) is formed as a flat edge (44) at a circumferential position intersecting a radial direction perpendicular to the insertion direction (D) and the third connection (13) has a flat inner side face adapted to abut against the flat edge (44).

11. Transmission mechanism according to claim 10, characterized in that said straight edge (44) is parallel to said insertion direction (D).

12. The transmission mechanism according to claim 1, wherein the housing (10) is provided with protrusions protruding outward in a radial direction with respect to the rotation Axis (AX) with respect to a housing wall at both axial sides of the mounting groove (101), the protrusions including a plurality and being spaced apart in the circumferential direction.

13. The transmission mechanism according to claim 12, wherein the housing (10) has a connecting portion provided at substantially the same circumferential position as the convex portion, the connecting portion connecting two portions of the housing (10) on both sides in the axial direction of the mounting groove (101), the housing (10) being formed as an integral member.

14. Transmission according to claim 13, characterized in that the connection extends in the radial direction in the region of the housing wall and/or the projection.

15. The transmission mechanism according to claim 1, wherein the lock ring (40) has a tooth portion (41) protruding from an inner surface of the housing (10) in a radial direction inward with respect to the rotation Axis (AX), and the switch member (30) has a groove portion (33), and in the lock position, the tooth portion (41) is engaged with the groove portion (33), and in the unlock position, the tooth portion (41) is disengaged from the groove portion (33).

16. Transmission according to claim 15, wherein the teeth (41) are provided in a plurality and are circumferentially symmetrically distributed on the locking ring (40) matching the fitting characteristics of the locking ring (40).

17. Transmission mechanism according to claim 15, wherein the gear unit (20) comprises a planetary gear train on a side of the locking ring (40) facing away from the switch (30), the planetary gear train comprising an annulus gear in mesh with a plurality of planetary gears, the teeth (41) of the locking ring (40) abutting an axial end of the annulus gear.

18. A transmission mechanism according to any one of claims 1 to 17, characterized in that the gear unit (20) comprises at least one stage of a planetary gear train, each stage of the at least one stage of a planetary gear train comprising a sun gear and a plurality of planetary gears meshing with the sun gear;

wherein the switch (30) has an inner tooth (32), in the unlocked position the inner tooth (32) of the switch (30) simultaneously meshes with a sun gear of one planetary gear train and with a plurality of planet gears, in the locked position the inner tooth (32) of the switch (30) disengages from the sun gear of the one planetary gear train and remains meshed with the plurality of planet gears of the one planetary gear train.

19. Transmission according to claim 18, characterized in that the sun gear has a large-diameter tooth for meshing with the internal tooth (32) and a small-diameter tooth axially offset with respect to the large-diameter tooth and for meshing with a plurality of planet gears of a planetary gear train of the same stage.

20. A power tool, characterized in that the power tool comprises:

a motor having an input shaft for generating torque;

an output shaft (2), the output shaft (2) being used for outputting torque outwards; and

the transmission mechanism according to any one of claims 1 to 19, the gear unit (20) being in driving coupling with the input shaft and the output shaft (2), respectively.