Rotary music box
By adopting multiple nested gears and ring-shaped structures in the music box, multi-directional rotation is achieved, which solves the problems of large space occupation and insufficient ornamentality of traditional music box, improves ornamentality and fun, and provides a removable and connected learning opportunity.
Patent Information
- Application Number
- CN202420772172.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-15
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-04-15
AI Technical Summary
The rotating structure of the traditional music box takes up a lot of space, lacks ornamentality and fun, and cannot meet modern needs.
Using multiple gear structures and ring-like structures on the bottom plate, the transmission settings of the main rotating shaft, inner ring and outer ring are used to realize multi-directional rotation of the music box surface decoration parts, forming three rotational trajectories to improve space utilization and ornamentality.
It reduces the space occupied by the music box, enhances the viewing and fun, and at the same time, it trains the user's hands-on ability through the detachable connection structure, helping to learn the principles of mechanical structures and electronic devices.
Smart Images
Figure CN223051864U_ABST
Abstract
Description
Technical Field
[0001] The utility model mainly relates to the technical field of music boxes, in particular to a rotating music box. Background Art
[0002] The music box is a mechanical musical instrument invented by Swiss watchmaker Antoine Fabre in 1796. Rotating the chain inside the box can automatically play music. With the development of science and technology, people's requirements for music boxes have increased. Traditional music boxes can only rotate in a single direction, and their viewing and interesting aspects cannot meet today's requirements.
[0003] The prior art installs a counterclockwise rotating disc and a clockwise rotating base on the music box base, and connects them to the main shaft to make the decorative parts on the surface of the music box rotate in different directions. However, the counterclockwise rotating disc and the clockwise rotating base are stacked in the music box, which takes up a large space of the music box. The overall volume of the music box is large and not easy to store. In addition, there are only two rotation tracks on the surface of the music box, which is not very ornamental. Utility Model Content
[0004] In view of the above-mentioned problems existing in the prior art, the purpose of the utility model is to provide a rotating music box, which drives the decorative parts on the surface of the music box to rotate in different directions through a plurality of gear structures and annular structures nested with each other on the bottom plate, thereby improving the utilization rate of the internal space of the music box, and through the arrangement of the main shaft, inner ring and outer ring, three rotation trajectories are formed on the surface of the music box, thereby improving the ornamental value of the music box.
[0005] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a rotating music box, including a music box body, the music box body including a bottom plate and a base plate, after the base plate is connected to the bottom plate, an accommodating space is provided inside, a driving mechanism is provided on the bottom plate, and the driving mechanism is located in the accommodating space, a plurality of first rotating gears are provided on the base plate, an outer ring is meshed with the upper side of the plurality of first rotating gears, an inner ring is horizontally meshed with the one side of the plurality of first rotating gears, a plurality of second rotating gears are horizontally meshed with the inner side of the inner ring, and the second rotating gears are meshed with the gears on the driving mechanism.
[0006] Preferably, a ring gear is provided under the outer ring, the ring gear is placed on the base plate, and the ring gear is meshed with a plurality of first rotating gears. The outer ring is driven to rotate in a horizontal plane higher than the first transmission gear through the meshing and rotation of the ring gear and the first rotating gears.
[0007] Preferably, a plurality of inverted L-shaped first limit clamps are further provided on the base plate, and the first limit clamps limit the rotation track position of the outer ring to prevent the outer ring from separating from the first rotating gear.
[0008] Preferably, a plurality of inverted L-shaped second limiting members are further provided on the substrate, and the second limiting members limit the position of the inner ring rotation track to prevent the inner ring from disengaging from the first rotation gear and the second rotation gear.
[0009] Preferably, a top cover is further included, and the top cover is disposed outside the music box body. The top cover is connected to the substrate in a clamping manner and is connected to the bottom plate in a clamping manner.
[0010] Furthermore, the top cover includes an outer wall and an inner wall. A plurality of first mortise interfaces are formed on the outer wall, and a plurality of first tenon joints are formed on the outer periphery of the substrate, and the first mortise interfaces and the first tenon joints fit with each other. A plurality of second tenon joints are formed at the lower end of the inner wall, and a plurality of second mortise interfaces are formed on the outer periphery of the bottom plate, and the second tenon joints and the second mortise interfaces fit with each other. The outer wall of the top cover is connected to the substrate in a clamping manner through a mortise and tenon structure, and the inner wall of the top cover is connected to the bottom plate in a clamping manner.
[0011] Furthermore, the outer wall is a non-closed outer wall, and a notch is provided on the outer wall. Some details of the outer ring can be observed through the notch.
[0012] Preferably, the driving mechanism includes a music box movement and a main rotating shaft. The music box movement is disposed on the bottom plate, the main rotating shaft is located above the music box movement, a gear structure is disposed between the music box movement and the main rotating shaft, and the gear structure is in transmission connection with the lower end of the main rotating shaft. The gear structure is driven to rotate by the music box movement, the gear structure drives the main rotating shaft to rotate, a gear is provided on the main rotating shaft, and the gear on the main rotating shaft meshes with the second rotation gear.
[0013] Furthermore, a spring is inserted into the lower end surface of the bottom plate, and the spring penetrates the bottom plate and is connected to the input end of the music box movement to drive the music box movement through the spring.
[0014] Furthermore, a base is detachably disposed on the lower end surface of the bottom plate. A cross-shaped tenon joint is provided on the top of the base, and the cross-shaped tenon joint is embedded in a cross-shaped mortise interface formed on the bottom plate, and the base is detachable from the bottom plate through the protrusion and the card slot.
[0015] Preferably, a magnetic member is fixed on the inner ring, and a magnetic ornament is provided on the top cover. The rotation of the inner ring drives the magnetic member to rotate, and the magnetic member magnetically attracts and drives the magnetic ornament on the top cover to rotate. The magnetic ornament on the top cover rotates along the rotation track of the inner ring through the magnetic member.
[0016] Preferably, a shaft and a shaft sleeve are inserted into the first rotation gear, and the shaft and the shaft sleeve limit and fix the first rotation gear in the vertical direction to prevent the first rotation gear from sliding out of the substrate in the vertical direction, and the limiting and fixing method of the second rotation gear is the same as that of the first rotation gear.
[0017] Compared with the prior art, the utility model has the following beneficial effects:
[0018] 1. The utility model provides a rotating music box. Through the first rotating gear, the second rotating gear, the inner ring and the outer ring that are nested and interlocked with each other on the bottom plate, the decorative parts on the surface of the music box are driven to rotate in different directions, occupying a smaller internal space of the music box and improving the utilization rate of the internal space of the music box.
[0019] 2. The utility model provides a rotating music box. Through the transmission arrangement of the main rotating shaft, the first rotating gear, the second rotating gear, the inner ring and the outer ring, after the music box is started, the decorative structures outside the top cover rotate along three rotation trajectories at the same time, enhancing the ornamental value of the music box.
[0020] 3. The utility model provides a rotating music box. Through the mortise and tenon structure settings between the top cover and the base plate, the top cover and the bottom plate, and the bottom plate and the base, the detachable connection of the music box is realized. When the user disassembles and assembles, the hands-on ability is exercised, and it can also help the user learn the mechanical structure and the principle of the electronic device in the product. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The drawings are only used to illustrate the specific implementation manners of the utility model and the principles, implementation manners, applications, features, effects, etc. of other related contents, and should not be considered as a limitation to the utility model.
[0022] In the accompanying drawings of the specification:
[0023] Figure 1 is the overall structure schematic diagram of the embodiment of the utility model;
[0024] Figure 2 is the main perspective structure schematic diagram of the embodiment of the utility model;
[0025] Figure 3 is the exploded schematic diagram of the connection structure between the top cover and the music box main body of the embodiment of the utility model;
[0026] Figure 4 is the exploded schematic diagram of the gear structure of the music box main body of the embodiment of the utility model;
[0027] Figure 5 is the schematic diagram of the connection structure of the base of the embodiment of the utility model;
[0028] Figure 6 is the bottom perspective structure schematic diagram of the music box main body of the embodiment of the utility model;
[0029] Reference numerals:
[0030] 1. Base; 2. Music box body; 21. Bottom plate; 211. Second mortise interface; 212. Cross mortise interface; 22. Music box movement; 23. Main rotating shaft; 24. Outer ring; 25. Magnetic part; 26. Second rotating gear; 27. Inner ring; 28. First rotating gear; 29. Substrate; 291. First tenon joint; 201. First limit card; 202. Second limit card; 3. Top cover; 31. Outer wall; 311. First mortise interface; 32. Inner wall; 321. Second tenon joint; 4. Self-rotating ornament; 5. Magnetic ornament; 6. Spring. Detailed implementation mode
[0031] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. The components of the embodiments of the present utility model described and illustrated herein can be arranged and designed in a variety of different configurations. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.
[0032] In the description of the embodiments of the present utility model, it should be noted that if terms such as "upper", "lower", "left", "right", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of this utility model is normally placed, it is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model.
[0033] In the description of the embodiments of the present utility model, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set" and "connected" are understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0034] Embodiment 1
[0035] As Figures 1 to 6As shown, a rotary music box includes a music box main body 2, and the music box main body 2 includes a bottom plate 21 and a base plate 29. After the base plate 29 is connected to the bottom plate 21, there is an accommodation space inside. A driving mechanism is provided on the bottom plate 21, and the driving mechanism is located in this accommodation space. A plurality of first rotating gears 28 are provided on the base plate 29. In this embodiment, to show the features of this product, three first transmission gears 28 are preferably provided. However, in other embodiments, the number of first transmission gears 28 can be freely selected and is not limited thereto. The plurality of first rotating gears 28 are arranged in a circular array with the center of the base plate as the center of the circle. Above one side of the plurality of first rotating gears 28, an outer ring 24 is meshed. Horizontally meshed with the other side of the plurality of first rotating gears 28 is an inner ring 27. Horizontally meshed inside the inner ring 27 are a plurality of second rotating gears 26. Similarly, in this embodiment, to show the features of this product, three second rotating gears 26 are preferably provided. However, in other embodiments, the number of second rotating gears 26 can be freely selected and is not limited thereto. The plurality of second rotating gears 26 are arranged in a circular array with the center of the base plate as the center of the circle. The plurality of second rotating gears 26 are meshed with the gears on the driving mechanism.
[0036] Below the outer ring 24 is provided a ring gear, and the diameter of the ring gear matches that of the outer ring 24. When looking down from a high place, the teeth of the ring gear are exactly blocked by the outer ring. The ring gear is placed on the base plate 29, and the ring gear is meshed with the plurality of first rotating gears 28. Due to the setting of the ring gear, the rotation horizontal plane of the entire outer ring 24 is higher than the rotation horizontal plane of the first rotating gears 28. A plurality of notches are opened on the outer ring 24, and corresponding bayonets are opened on the ring gear. The outer ring 24 and the ring gear are fixedly connected by inserting a plurality of T-shaped plugs into the notches and bayonets in sequence. Of course, in some other embodiments, the ring gear and the outer ring 24 are riveted, or the ring gear and the outer ring 24 can be integrally formed, or the ring gear and the outer ring can be connected by bolts or screws.
[0037] On the base plate 29 are also provided a plurality of inverted L-shaped first limiting clips 201. In this embodiment, to show the features of this product, four inverted L-shaped first limiting clips 201 are preferably provided. However, in other embodiments, the number of inverted L-shaped first limiting clips 201 can be freely selected and is not limited thereto. One end of the first limiting clip 201 presses against the outer ring 24, restricting the rotation track position of the outer ring 24, preventing the outer ring 24 from radially disengaging from the first rotating gears 28, and simultaneously preventing the outer ring 24 from axially disengaging from the first rotating gears 28. The plurality of inverted L-shaped first limiting clips 201 are arranged in a circular array with the center of the base plate as the center of the circle.
[0038] A plurality of inverted L-shaped second limiting members 202 are further provided on the substrate 29. In this embodiment, to show the features of the product, three inverted L-shaped second limiting members 202 are preferably provided. However, in other embodiments, the number of inverted L-shaped second limiting members 202 can be freely selected and is not limited thereto. One end of the second limiting member 202 presses against the inner ring 27 to limit the rotation track position of the inner ring 27 and prevent the inner ring 27 from disengaging from the first rotating gear 28 and / or the second rotating gear 26 in the radial or axial direction. The inverted L-shaped second limiting members 202 are distributed in a circumferential array with the center of the substrate as the center of the circle.
[0039] The rotating music box of this solution further includes a top cover 3. The top cover 3 is arranged outside the music box body 2. The top cover 3 includes an outer wall 31 and an inner wall 32. A plurality of first mortise interfaces 311 are formed on the outer wall 31. In this embodiment, to show the features of the product, fifteen first mortise interfaces 311 are preferably provided. However, in other embodiments, the number of first mortise interfaces 311 can be freely selected and is not limited thereto. A plurality of first tenon joints 291 are formed on the outer periphery of the substrate 29. In this embodiment, to show the features of the product, fifteen first tenon joints 291 are preferably provided. However, in other embodiments, the number of first tenon joints 291 can be freely selected and is not limited thereto. The first mortise interfaces 311 and the first tenon joints 291 fit with each other. By inserting the first tenon joints 291 into the first mortise interfaces 311, a mortise and tenon structure clamping connection between the top cover 3 and the substrate 29 is realized. A plurality of second tenon joints 321 are formed at the lower end of the inner wall 32. In this embodiment, to show the features of the product, sixteen second tenon joints 321 are preferably provided. However, in other embodiments, the number of second tenon joints 321 can be freely selected and is not limited thereto. A plurality of second mortise interfaces 211 are formed on the outer periphery of the bottom plate 21. Similarly, in this embodiment, to show the features of the product, sixteen second mortise interfaces 211 are preferably provided. However, in other embodiments, the number of second mortise interfaces 211 can be freely selected and is not limited thereto. The second tenon joints 321 and the second mortise interfaces 211 fit with each other. By inserting the second tenon joints 321 into the second mortise interfaces 211, a mortise and tenon structure clamping connection between the top cover 3 and the bottom plate 21 is realized.
[0040] The outer wall 31 is a non-closed outer wall, and a notch with a cross-section of one-fourth of a circular ring size is opened on its periphery, so that a part of the outer ring 24 is shown from the notch of the outer wall 31. Through the notch, the dynamic scene during the rotation of the outer ring 24 can be observed.
[0041] The driving mechanism includes a music box movement 22 and a main rotating shaft 23. The music box movement 22 is arranged on the bottom plate 21. The main rotating shaft 23 is located above the music box movement 22. A gear structure is arranged between the music box movement 22 and the main rotating shaft 23. The gear structure is in transmission connection with the lower end of the main rotating shaft 23 and is also in transmission connection with the music box movement 22. The music box movement 22 drives the gear structure to rotate. The rotation direction can be clockwise or other directions, not limited to this. Further, it drives the main rotating shaft 23 to rotate. Similarly, the rotation direction can be clockwise or other directions, not limited to this. A gear is provided on the main rotating shaft 23, and the gear on the main rotating shaft meshes with the second rotating gear 26.
[0042] A winding spring 6 is inserted into the lower end surface of the bottom plate 21. The winding spring 6 penetrates the bottom plate 21 and is connected to the input end of the music box movement 22. A base 1 is detachably arranged on the lower end surface of the bottom plate 21. A cross-shaped mortise joint is provided at the top of the base 1, and this cross-shaped mortise joint is embedded in the cross-shaped tenon interface 212 formed on the bottom plate 21 to form a detachable mortise and tenon connection.
[0043] A magnetic component 25 is fixed on the inner ring 27. A magnetic ornament 5 is arranged on the top cover. The rotation of the inner ring 27 drives the magnetic component 25 to rotate. The magnetic component 25 magnetically attracts and pulls the magnetic ornament 5 to rotate around the main rotating shaft 23 on the top cover 3. The rotation direction of the magnetic component 25 can revolve around the main rotating shaft 23 in the counterclockwise direction or rotate in the clockwise direction. The rotation direction is not limited to this.
[0044] The center position of the first rotating gear 28 is connected to the substrate 29 through a shaft. The first rotating gear 28 is sleeved on the shaft, and a shaft sleeve is also sleeved on the shaft at the upper end position of the first rotating gear 28. The shaft and the shaft sleeve limit and fix the first rotating gear 28 in the vertical direction to prevent the first rotating gear 28 from sliding out of the substrate in the vertical direction. Similarly, the center position of the second rotating gear 26 is also connected to the substrate 29 through a shaft. The second rotating gear 26 is sleeved on the shaft, and a shaft sleeve is also sleeved on the shaft at the upper end position of the second rotating gear 26. The shaft and the shaft sleeve limit and fix the second rotating gear 26 in the vertical direction to prevent the second rotating gear 26 from sliding out of the substrate in the vertical direction.
[0045] A self-rotating ornament 4 is arranged at the position corresponding to the main rotating shaft 23 on the upper end surface of the top cover 3. The self-rotating ornament 4 is detachably connected to the main rotating shaft 23. The main rotating shaft 23 rotates in the clockwise direction, driving the self-rotating ornament 4 to rotate clockwise. Of course, in some other embodiments, the rotation direction is not limited to this.
[0046] The implementation principle of Embodiment 1 of this application is as follows: A spring 6 is inserted below the music box main body 2. Rotating the spring 6 causes the music box movement 22 to start working, emit music, and drive the main rotating shaft 23 and the self-rotating ornament 4 above the main rotating shaft to rotate in the clockwise direction through a gear structure. During the rotation of the main rotating shaft 23, the gear on the main rotating shaft 23 drives the engaged second rotating gear 26 to rotate. The second rotating gear 26 further drives the engaged inner ring 27 and the magnetic ornament 5 above the inner ring 27 to rotate in the counterclockwise direction. The first rotating gear 28 on the outer periphery of the inner ring 27 rotates under the engagement of the inner ring 27, and further drives the outer ring 24 engaged with the first rotating gear 28 to rotate in the clockwise direction. The outer ring 24, the self-rotating ornament 4, and the magnetic ornament 5 are driven to rotate along different trajectories through the nested gear structure; the connections between the base 1, the music box main body 2, and the top cover 3 are detachably connected by a mortise and tenon structure. When assembling, the tenon joint of the base 1 can be inserted into the corresponding mortise opening on the music box main body 2 for snap fixation. When disassembling, the tenon joint of the base 1 can be pulled out from the mortise opening to separate the components. The assembly and disassembly method between the music box main body 2 and the top cover 3 is the same as above.
[0047] For those skilled in the art, it is obvious that this application is not limited to the details of the above exemplary embodiments, and without departing from the basic features of this application, this application can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of this application is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in this application. Any reference signs in the claims should not be regarded as limiting the claims involved.
Claims
1. A rotating music box, comprising a music box body (2), characterized in that: The music box body (2) comprises a bottom plate (21) and a base plate (29). The base plate (29) is connected to the bottom plate (21) and has an internal storage space. The bottom plate (21) is provided with a driving mechanism, and the driving mechanism is located in the storage space. The base plate (29) is provided with a plurality of first rotating gears (28). One side of the plurality of first rotating gears (28) is meshed with an outer ring (24), and the other side of the plurality of first rotating gears (28) is meshed with an inner ring (27). The inner side of the inner ring (27) is meshed with a plurality of second rotating gears (26), and the second rotating gears (26) are meshed with gears on the driving mechanism.
2. A rotating music box according to claim 1, characterized in that: A ring gear is provided below the outer ring (24), the ring gear is placed on a base plate (29), and the ring gear is meshed with a plurality of first rotating gears (28).
3. A rotating music box according to claim 2, characterized in that: The outer ring is provided with a plurality of notches, and the ring gear is provided with corresponding bayonet holes. The outer ring and the ring gear are connected by inserting a plurality of T-shaped plug-ins into the notches and the bayonet holes in sequence.
4. A rotating music box according to claim 1, characterized in that: The base plate (29) is also provided with a plurality of inverted L-shaped first limit clamps (201), the first limit clamps (201) limiting the rotation track position of the outer ring (24) to prevent the outer ring (24) from detaching from the first rotating gear (28).
5. A rotating music box according to claim 1, characterized in that: The base plate (29) is also provided with a plurality of inverted L-shaped second limit clamps (202), the second limit clamps (202) limiting the rotation track position of the inner ring (27) to prevent the inner ring (27) from being separated from the first rotating gear (28) and the second rotating gear (26).
6. A rotating music box according to claim 1, characterized in that: The music box further comprises a top cover (3), the top cover (3) being arranged outside the music box body (2), the top cover (3) being connected to the base plate (29) by clamping, and the top cover (3) being connected to the bottom plate (21) by clamping.
7. A rotating music box according to claim 6, characterized in that: The top cover (3) comprises an outer wall (31) and an inner wall (32); a plurality of first mortise and tenon interfaces (311) are formed on the outer wall (31); a plurality of first tenon and tenon joints (291) are formed on the outer periphery of the base plate (29); the first mortise and tenon interfaces (311) and the first tenon and tenon joints (291) fit together; a plurality of second tenon and tenon joints (321) are formed at the lower end of the inner wall (32); a plurality of second mortise and tenon interfaces (211) are formed on the outer periphery of the base plate (21); the second tenon and tenon joints (321) and the second mortise and tenon interfaces (211) fit together.
8. A rotating music box according to claim 7, characterized in that: The outer wall (31) is a non-closed outer wall (31), and a notch is provided on the outer wall (31), through which some details of the outer ring (24) can be observed.
9. A rotating music box according to claim 1, characterized in that: The driving mechanism comprises a music box movement (22) and a main rotating shaft (23); the music box movement (22) is arranged on a bottom plate (21); the main rotating shaft (23) is located above the music box movement (22); a gear structure is arranged between the music box movement (22) and the main rotating shaft (23); the music box movement (22) drives the gear structure to rotate; the gear structure drives the main rotating shaft (23) to rotate; a gear is arranged on the main rotating shaft (23); the gear on the main rotating shaft is meshed with a second rotating gear (26).
10. A rotating music box according to claim 9, characterized in that: A spring (6) is inserted into the lower end surface of the bottom plate (21), and the spring (6) penetrates the bottom plate (21) and is connected to the input end of the music box movement (22).
11. A rotating music box according to claim 9, characterized in that: A base (1) is detachably provided on the lower end surface of the bottom plate (21), and a cross-tenon joint is provided on the top of the base (1), wherein the cross-tenon joint is embedded in a cross-mortise interface (212) formed on the bottom plate (21).
12. A rotating music box according to claim 6, characterized in that: A self-rotating pendulum (4) is arranged at a position on the upper end surface of the top cover (3) corresponding to the main rotating shaft (23); the self-rotating pendulum (4) is detachably connected to the main rotating shaft (23); the main rotating shaft (23) rotates in a clockwise direction, driving the self-rotating pendulum (4) to rotate in a clockwise direction.
13. A rotating music box according to claim 6, characterized in that: A magnetic attraction member (25) is fixed on the inner ring (27), and a magnetic attraction swing member (5) is arranged on the top cover. The inner ring (27) rotates to drive the magnetic attraction member (25) to rotate, and the magnetic attraction member (25) magnetically attracts and pulls the magnetic attraction swing member (5) to rotate on the top cover (3).
14. A rotating music box according to claim 1, characterized in that: A shaft and a shaft sleeve are inserted into the first rotating gear (28), and the shaft and the shaft sleeve limit and fix the first rotating gear (28) in a vertical direction to prevent the first rotating gear (28) from sliding out of the base plate (29) in a vertical direction, and the limiting and fixing method of the second rotating gear (26) is the same as that of the first rotating gear (28).