Speed limiting mechanism and propelling mechanism comprising same

Abstract

The utility model provides a speed limiting mechanism and a propulsion mechanism including the speed limiting mechanism, the speed limiting mechanism comprises a rack and a screw rod used for installing the speed limiting mechanism on the propulsion mechanism, the rack is provided with a meshing tooth groove, the screw rod comprises helical teeth matched with the meshing tooth groove, and the helical teeth are matched with the meshing tooth groove. The spiral teeth are meshed with the meshing tooth grooves so as to limit the moving speed of the worm on the rack, and the contact faces of the spiral teeth and the meshing tooth grooves are in face contact. Movement of the push plate is limited through friction force between the spiral teeth and the meshed tooth grooves, so that the effect of reducing the speed of the push plate or enabling the push plate to move at a constant speed is achieved, the problem that the push plate of the propeller moves too fast is solved, and application and popularization of the propelling mechanism in shopping malls, supermarkets, convenience stores or department stores are facilitated.

Description

Technical Field

[0001] This utility model relates to the field of propulsion mechanism technology, specifically to a speed limiting mechanism and a propulsion mechanism including the speed limiting mechanism. Background Technology

[0002] The push mechanism is an automated merchandising device used on retail shelves in shopping malls, supermarkets, convenience stores, department stores, etc. It helps organize the goods on the shelves. After a customer takes a product from the shelf, the push mechanism can push the product from the back of the shelf to the front, always keeping the front of the shelf displaying goods. It can assist in merchandising, especially during restocking and sorting. Staff do not need to manually arrange and place goods, so it has high application value.

[0003] However, existing propulsion mechanisms mainly rely on springs to reset the push plate. In actual use, the spring reset causes the push plate to move too fast, which can easily cause the goods to tip over and get damaged. It is also impossible to stably propel the goods and requires additional manual maintenance on a regular basis.

[0004] Therefore, a speed limiting mechanism is urgently needed to solve the problem of excessively fast movement speed of the propulsion mechanism. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model proposes a speed limiting mechanism and a propulsion mechanism including the speed limiting mechanism, which can decelerate the push plate or make the push plate move at a constant speed, thus solving the problem of excessively fast movement speed of the push plate in the propeller. This is beneficial for the promotion and application of the propulsion mechanism in shopping malls, supermarkets, convenience stores, or department stores.

[0006] The technical solution of this utility model is implemented as follows:

[0007] The first aspect of this utility model provides a speed limiting mechanism, including a rack and a helical rod for mounting the speed limiting mechanism on a propulsion mechanism. The rack is provided with a meshing tooth groove, and the helical rod includes helical teeth adapted to the meshing tooth groove. The helical teeth mesh with the meshing tooth groove to limit the moving speed of the worm gear on the rack, and the contact surface between the helical teeth and the meshing tooth groove is a surface contact.

[0008] In a preferred embodiment of the first aspect of the utility model, the surface contact includes single-sided contact and double-sided contact. The single-sided contact is when the helical tooth forms a surface contact with one of the two groove walls in the meshing tooth groove, and the double-sided contact is when the helical tooth forms a surface contact with both groove walls of the meshing tooth groove.

[0009] In a first aspect of the utility model, as a preferred embodiment, the angle between the helical tangent of the helical tooth and the plane perpendicular to the helical axis tangent is in the range of 3.5°-4.5°.

[0010] In a first aspect of the utility model, as a preferred embodiment, the depth of the meshing groove is in the range of 50%-90% of the height of the helical tooth.

[0011] In a preferred embodiment of the first aspect of the utility model, both the meshing tooth groove and the contact surface of the helical tooth are provided with a wear-resistant coating.

[0012] The second aspect of this utility model provides a propulsion mechanism, including a speed limiting mechanism as described in the first aspect, wherein the propulsion mechanism includes a propulsion component, a plug, and a slide.

[0013] The propulsion assembly includes a spring, a baffle disposed at the front end of the plug, and a push plate slidably connected in the slide. One end of the spring is wound inside the push plate, and the other end of the spring passes through the push plate and is fixedly connected to the plug. When the push plate moves to the rear end of the slide, the push plate is fixed on the slide by a snap-fit ​​assembly.

[0014] The push plate is provided with a mounting part by bolt connection, and the mounting part is provided with mounting holes for movably mounting the screw rod;

[0015] The rack is disposed within the slide rail, and the helical teeth on the helical rod mesh with the meshing grooves on the rack;

[0016] The plug is installed at both ends of the slide.

[0017] In a second aspect of the utility model, as a preferred embodiment, the plug includes a plug body and a movable block. Movable grooves for movably mounting the movable block are respectively provided on both sides of the plug body. At least one protrusion is provided on the surface of the movable block. At least one engaging portion is provided on the inner wall of the movable groove to grade the length of the movable groove. The protrusion engages with the engaging portion to allow the movable block to adjust its extension and retraction length in multiple stages within the movable groove. An insertion portion for mounting a separator is provided at the end of the movable block away from the plug body, and a separator is inserted into the insertion portion.

[0018] In a second aspect of the utility model, as a preferred embodiment, the slide rail includes a rack area for mounting the rack, a propulsion area for slidably mounting the propulsion assembly, and a guide area for guiding the sliding article.

[0019] In a second aspect of the utility model, as a preferred embodiment, the buckle assembly includes a first buckle disposed at the rear end of the propulsion zone and a first snap-fit ​​groove disposed at the bottom of the push plate. When the push plate moves to the rear end of the propulsion zone, the first buckle snaps into the first snap-fit ​​groove to fix the push plate to the rear end of the propulsion zone.

[0020] In a second aspect of the utility model, as a preferred embodiment, the buckling assembly includes a second buckle disposed at the rear end of the propulsion zone and a third buckle disposed on the push plate. When the push plate moves to the rear end of the propulsion zone, the second buckle engages with the third buckle to fix the push plate to the rear end of the propulsion zone.

[0021] The second buckle includes an L-shaped first snap-fit ​​end, and the third buckle includes a mounting buckle fixedly disposed on the push plate and a first snap-fit ​​buckle snapped in the mounting buckle. The first snap-fit ​​buckle includes an L-shaped second snap-fit ​​end. When the push plate moves to the rear end of the push area, the first snap-fit ​​end extends into the first snap-fit ​​buckle and snaps into the second snap-fit ​​end.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This utility model proposes a speed limiting mechanism and a propulsion mechanism including the speed limiting mechanism. The speed limiting mechanism includes a rack and a helical rod for mounting the speed limiting mechanism on the propulsion mechanism. The rack has meshing tooth grooves, and the helical rod includes helical teeth adapted to the meshing tooth grooves. The helical teeth mesh with the meshing tooth grooves to limit the movement speed of the worm gear on the rack. The contact surfaces of the helical teeth and the meshing tooth grooves are surface contacts. By mounting the speed limiting mechanism on the propulsion mechanism, the friction between the helical teeth and the meshing tooth grooves limits the movement of the push plate, thereby achieving the effect of decelerating the push plate or making the push plate move at a constant speed. This solves the problem of excessively fast push plate movement in propulsion devices and is beneficial for the widespread application of propulsion mechanisms in shopping malls, supermarkets, convenience stores, or department stores. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of a speed limiting mechanism in Embodiment 1 of this utility model;

[0026] Figure 2This is a schematic diagram of a propulsion mechanism including a speed limiting mechanism in Embodiment 2 of this utility model;

[0027] Figure 3 This is a schematic diagram of the slide structure in Embodiment 2 of this utility model;

[0028] Figure 4 This is embodiment 2 of the present utility model. Figure 2 Another perspective on the structural diagram of the snap-fit ​​assembly;

[0029] Figure 5 This is a schematic diagram of the pusher plate inside the propulsion assembly in Embodiment 2 of this utility model;

[0030] Figure 6 This is a schematic diagram of the plug head in Embodiment 2 of this utility model;

[0031] Figure 7 This is embodiment 2 of the present utility model. Figure 6 Schematic diagram of the structure of the middle stopper head body;

[0032] Figure 8 This is embodiment 2 of the present utility model. Figure 6 A schematic diagram of the structure of the active block;

[0033] Figure 9 This is a schematic diagram of a propulsion mechanism including a speed limiting mechanism in Embodiment 3 of this utility model;

[0034] Figure 10 for Figure 9 Enlarged view of point A in the middle;

[0035] Figure 11 This is a schematic diagram of the third buckle in Embodiment 3 of this utility model;

[0036] Figure 12 This is a schematic diagram of a propulsion mechanism including a speed limiting mechanism in Embodiment 4 of this utility model.

[0037] Attached image labels:

[0038] 1-Rack, 11-Meshing tooth groove;

[0039] 2-Helical rod, 21-Helical teeth;

[0040] 3-Propulsion assembly, 31-Spring, 32-Baffle, 33-Push plate, 331-Mounting part, 332-Mounting hole, 333-Bolt;

[0041] 4-Plug, 41-Plug body, 411-Modular groove, 412-Interlocking part, 42-Modular block, 421-Protrusion, 422-Insertion part, 43-Separator;

[0042] 5-Slide, 5A-Rack and pinion area, 5B-Propulsion area, 5C-Guide area;

[0043] 6-Snap-on assembly, 61-First snap-on, 62-First snap-on slot, 63-Second snap-on, 64-Third snap-on, 641-Mounting buckle, 642-First snap-on buckle;

[0044] 7-Damper. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," "third," and "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0048] Example 1

[0049] See Figures 1-11 The first aspect of this utility model provides a speed limiting mechanism, including a rack 1 and a screw rod 2 for mounting the speed limiting mechanism on a propulsion mechanism. The rack 1 is provided with a meshing tooth groove 11, and the screw rod 2 includes helical teeth 21 adapted to the meshing tooth groove 11. The helical teeth 21 mesh with the meshing tooth groove 11 to limit the moving speed of the screw rod 2 on the rack 1, and the contact surface between the helical teeth 21 and the meshing tooth groove 11 is a surface contact.

[0050] It should be noted that existing propulsion mechanisms consist of a pusher mounted on a slide. The pusher typically includes a base plate, a spring, and a push plate. In actual use, the spring's elastic contraction pulls the push plate towards the front of the slide, thus pushing the goods on the base plate or slide. However, while the elastic contraction of the spring provides a force to move the push plate, its movement speed is uncontrollable. Often, the excessively fast movement speed can suddenly push the goods (or cargo) on the slide (or base plate), causing damage or knocking over the goods. This is especially true for fragile items in glass packaging, which are easily broken by the sudden push. Excessive pushing speed can also cause goods to tip over or fall out of the slide, resulting in increased manpower costs for product damage and maintenance. The excessively fast movement speed of the pusher's push plate hinders the promotion of propulsion mechanisms in shopping malls, supermarkets, convenience stores, or department stores. Therefore, limiting the movement speed of the push plate is a problem that urgently needs to be solved for propulsion mechanisms.

[0051] Specifically, this utility model proposes a speed limiting mechanism, the working principle of which is to limit the speed of the propulsion mechanism through the meshing helical teeth 21 and meshing grooves 11. The push plate 33 of the propulsion mechanism, after being pulled by the contraction of the spring 31, moves linearly along the length of the slide to the front end of the slide. The rack 1 is also arranged along the length of the slide. The helical rod 2 on the push plate 33 has a certain inclination angle due to the helical structure of the helical teeth 21. When the helical teeth 21 and the meshing grooves 11 are meshed, the push plate 33 moves linearly along the slide... The push plate 33 needs to overcome the friction between the helical teeth 21 and the meshing groove 11 to move back and forth. Therefore, during the movement of the push plate 33, the helical rod 2 also moves on the rack 1 through the meshing state of the helical teeth 21 and the meshing groove 11. The process of the push plate 33 overcoming the friction is to achieve the speed limit of the push plate 33. Under this speed limit state, the push plate 33 can be in a state of deceleration or in a state of maintaining a constant speed after deceleration. This can reduce the problem of product damage and the need for continuous maintenance caused by the push plate being too fast or suddenly accelerating.

[0052] In a preferred embodiment of the first aspect of the utility model, the surface contact includes single-sided contact and double-sided contact. The single-sided contact is when the helical tooth 21 forms a surface contact with one of the two groove walls in the meshing tooth groove 11, and the double-sided contact is when the helical tooth 21 forms a surface contact with both groove walls of the meshing tooth groove 11.

[0053] It should be noted that existing technologies often use worm gear assemblies to provide power transmission, mainly relying on the helical teeth and worm wheel teeth on the worm to achieve the transmission effect. Line contact between the helical teeth and worm wheel teeth is necessary to achieve maximum power transmission. However, in this application, the speed limiting mechanism, similar to a worm gear, aims to achieve better deceleration rather than transmission in the propulsion mechanism. The contact between the helical teeth 21 and the meshing groove 11 should be surface contact. This maximizes the contact area between the tooth surface of the helical teeth 21 and the groove surface of the meshing groove 11, thereby increasing the frictional force experienced by the helical teeth 21 as they move on the rack 1. This allows the propulsion mechanism to achieve deceleration or maintain a constant speed, thus solving the problem of excessively fast movement speed in existing propulsion mechanisms.

[0054] Furthermore, in the single-sided contact state, the cross-sections of both the helical tooth 21 and the meshing groove 11 are triangular structures. Therefore, the single-sided contact is the tooth surface of the helical tooth 21 and the groove surface of the meshing groove 11, which are close to the direction of the push plate's movement. Under single-sided contact, a frictional force can be generated to slow down the rotational speed of the helical rod 2, thereby decelerating the push plate 33 or keeping it at a constant speed. If in the double-sided contact state, the contact surface between the helical tooth 21 and the meshing groove 11 is the corresponding surface on the two sides of the non-base side of the triangular cross-section. This can increase the frictional force between the helical tooth 21 and the meshing groove 11, which can better decelerate the push plate 33 or keep it at a constant speed. It should be noted that the setting of single-sided contact and double-sided contact can be achieved by adjusting the cross-sectional width of the helical tooth 21 and the meshing groove 11. The specific cross-sectional width can be adjusted according to the deceleration requirements of the push plate.

[0055] In a preferred embodiment of the first aspect of the utility model, the angle between the helical tangent of the helical tooth 21 and the plane perpendicular to the helical axis tangent is in the range of 3.5°-4.5°.

[0056] Specifically, to prevent the lead angle of the helical tooth 21 (i.e., the angle between the helical tangent and the plane perpendicular to the helical axis tangent) from being too large and getting stuck in the meshing tooth groove 11, and to ensure that the push plate 33 can move stably on the slide 5 while being meshed with the helical tooth 21 and the meshing tooth groove 11, the lead angle of the helical tooth 21 is preferably between 3.5° and 4.5°, which reduces the failure risk of the speed limiting mechanism and increases the stability of the speed limiting mechanism on the propulsion mechanism.

[0057] In a preferred embodiment of the first aspect of the utility model, the depth of the meshing groove 11 is 50%-90% of the height of the helical tooth 21. Specifically, the meshing groove 11 and the helical tooth 21 cooperate with each other to prevent the helical tooth 21 from disengaging from the meshing groove 11, thereby preventing the speed limiting mechanism from failing to work due to tooth disengagement and increasing the stability of the speed limiting mechanism.

[0058] In a preferred embodiment of the first aspect of the utility model, the contact surfaces of the meshing groove 11 and the helical tooth 21 are provided with a wear-resistant coating. In actual use, in order to adjust the friction force on the contact surfaces of the meshing groove 11 and the helical tooth 21, the coating can be added. The wear-resistant coating can extend the service life of the speed limiting mechanism.

[0059] Example 2

[0060] See Figures 1-11 The second aspect of this utility model provides a propulsion mechanism, including a speed limiting mechanism as described in the first aspect, wherein the propulsion mechanism includes a propulsion component 3, a plug head 4, and a slide rail 5;

[0061] The propulsion assembly 3 includes a spring 31, a baffle 32 disposed at the front end of the plug 4, and a push plate 33 slidably connected in the slide rail 5. One end of the spring 31 is wound around the push plate 33, and the other end of the spring passes through the push plate 33 and is fixedly connected to the plug 4. When the push plate 33 moves to the rear end of the slide rail 5, the push plate 33 is fixed on the slide rail 5 by a snap-fit ​​assembly 6.

[0062] Specifically, the push plate 33 can be fixed on the slide rail 5 by the snap-fit ​​assembly 6, which facilitates the addition and replenishment of goods on the shelf, making it quite convenient.

[0063] The push plate 33 is provided with a mounting part 331 connected by bolts 333, and the mounting part 331 is provided with mounting holes 332 for movably mounting the spiral rod 2;

[0064] The rack 1 is disposed in the slide rail 5, and the helical teeth 21 on the helical rod 2 mesh with the meshing grooves 11 on the rack 1;

[0065] Specifically, the mounting part 331 provides a space to accommodate the spiral rod 2. The two ends of the spiral rod 2 are respectively inserted into the mounting holes 332 of the mounting part 331 so that the spiral rod 2 can rotate on the push plate 33. The spiral teeth 21 on the spiral rod 2 mesh with the meshing grooves 11 on the rack 1. When the push plate 33 moves, the spiral rod 2 is driven to rotate by the meshing state of the spiral teeth 21 and the meshing grooves 11. The contact surfaces of the spiral teeth 21 and the meshing grooves 11 have friction, which hinders the push plate 33 from continuing to move, thereby achieving the purpose of limiting the speed of the push plate 33.

[0066] The plug 4 is installed at both ends of the slide rail 5, and the plug 4 can be fixed at both ends of the slide rail 5 by means of a snap-fit ​​connection.

[0067] In a second aspect of the utility model, as a preferred embodiment, the plug 4 includes a plug body 41 and a movable block 42. The plug body 41 has movable grooves 411 on both sides for movably mounting the movable block 42. The surface of the movable block 42 has at least one protrusion 421. The inner wall of the movable groove 411 has at least one engaging part 412 for classifying the length of the movable groove 411. The protrusion 421 engages with the engaging part 412 to allow the movable block 42 to adjust its extension length in multiple stages within the movable groove 411. The end of the movable block 42 away from the plug body 41 has a plug-in part 422 for mounting a separator 43, and the separator 43 is inserted into the plug-in part 422.

[0068] Specifically, the movable block 42 can extend and retract within the movable groove 411, adjusting the length of the movable block 42 extending beyond the groove 411, thereby changing the spacing between the separators 43 mounted on the movable block 42. The protrusions 421 on the movable block 42 can engage with different engaging parts 412 in the inner wall of the movable groove 411 for fixation, thereby achieving multi-level adjustment of the extension and retraction length of the movable block 42. The spacing between the engaging parts 412 can be fixed at the same value or different values, and the protrusions 421 are elastic, allowing them to engage with the engaging parts 412 to fix the movable block during fixation. The movable block 42 has a telescopic length, and when it is pulled out or pushed in, the elastic protrusion 421 can disengage from the locking part 412 to readjust the telescopic length of the movable block 42 in the movable groove 411. The movable block 42 is pushed out or pushed back, and multiple positions are set by the locking part 412. Each time it is pushed forward by one position, the distance is widened, and each time it is pushed back by one position, the distance is narrowed. At the same time, there is a clear click sound feedback for each position adjustment (the protrusion 421 elastically deforms and engages with the locking part 412), indicating to the user that the distance of the position adjustment has been reached, so as to realize the flexibility of adjusting the length of the movable block 42 in multiple levels.

[0069] In a second aspect of the utility model, as a preferred embodiment, the slide 5 includes a rack area 5A for mounting the rack 1, a propulsion area 5B for sliding the propulsion assembly 3, and a guide area 5C for guiding the sliding object.

[0070] In a second aspect of the utility model, as a preferred embodiment, the latching assembly 6 includes a first latch 61 disposed at the rear end of the push zone 5B and a first latching groove 62 disposed at the bottom of the push plate 33. When the push plate 33 moves to the rear end of the push zone 5B, the first latch 61 engages in the first latching groove 62 to fix the push plate 33 to the rear end of the push zone 5B.

[0071] Example 3

[0072] like Figures 1-11 As shown, the difference between this embodiment 3 and embodiment 2 is that the buckle assembly 6 includes a second buckle 63 disposed at the rear end of the push area 5B and a third buckle 64 disposed on the push plate 33. When the push plate 33 moves to the rear end of the push area 5B, the second buckle 63 engages with the third buckle 64 to fix the push plate 33 to the rear end of the push area 5B.

[0073] The second buckle 63 includes an L-shaped first snap-fit ​​end, and the third buckle 64 includes a mounting buckle 641 fixedly disposed on the push plate 33 and a first snap-fit ​​buckle 642 snapped in the mounting buckle 641. The first snap-fit ​​buckle 642 includes an L-shaped second snap-fit ​​end. When the push plate 33 moves to the rear end of the push area 5B, the first snap-fit ​​end extends into the first snap-fit ​​buckle 642 and snaps into the second snap-fit ​​end.

[0074] Specifically, in this embodiment, when it is necessary to fix the push plate 33 on the slide rail 5, the first locking end extends into the first locking buckle 642 to lock the second locking end; when it is necessary to remove the push plate 33 from the slide rail 5, the push plate 33 is pushed towards the rear end of the slide rail 5 so that the first locking end and the second locking end disengage.

[0075] Example 4

[0076] like Figures 1-12 As shown, the difference between this embodiment 4 and embodiment 2 is that a damper 7 can be installed in the mounting part 331 between the screw rod 2 and the mounting hole 332. The movement state of the screw rod 2 can be further controlled by the damper 7. When deceleration is required, the damper 7 provides a force for the screw rod 2 to rotate in the opposite direction. In order to continue to move along the slide 5, the push plate 33 connected to the screw rod 2 needs to overcome the force provided by the damper 7 and the friction between the helical teeth 21 and the meshing tooth groove 11 at the same time, so as to realize the control of the propulsion mechanism. It can be considered whether to add a damper 7 to the speed limiting mechanism to limit the movement of the propulsion mechanism according to the actual use requirements.

[0077] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A speed limiting mechanism applied to a propulsion mechanism, characterized in that, The speed limiting mechanism comprises a rack (1) and a screw rod (2) for mounting the speed limiting mechanism on a propelling mechanism, the rack (1) is provided with engaging tooth grooves (11), the screw rod (2) comprises screw threads (21) matched with the engaging tooth grooves (11), the screw threads (21) are engaged with the engaging tooth grooves (11) to limit the moving speed of the screw rod (2) on the rack (1), and the contact surface of the screw threads (21) and the engaging tooth grooves (11) is surface contact.

2. The speed limiting mechanism of claim 1, wherein, The surface contact comprises single surface contact and double surface contact, the single surface contact is that the screw threads (21) form surface contact with one of the two groove walls in the engaging tooth grooves (11), and the double surface contact is that the screw threads (21) form surface contact with the two groove walls of the engaging tooth grooves (11).

3. The speed limiting mechanism of claim 1, wherein, The included angle between the tangent of the helix line of the screw threads (21) and the plane perpendicular to the tangent of the helix axis is 3.5-4.5°.

4. The speed limiting mechanism of claim 1, wherein, The depth of the engaging tooth grooves (11) is 50%-90% of the height of the screw threads (21).

5. The speed limiting mechanism of claim 1, wherein, The contact surfaces of the engaging tooth grooves (11) and the screw threads (21) are provided with wear-resistant coatings.

6. A propulsion mechanism comprising a speed limiting mechanism according to any one of claims 1-5, characterized in that The propelling mechanism comprises a propelling assembly (3), a plug head (4) and a slide (5). The propelling assembly (3) comprises a clockwork (31), a baffle (32) arranged at the front end of the plug head (4) and a push plate (33) slidably connected in the slide (5), one end of the clockwork (31) is arranged in the push plate (33), the other end of the clockwork (31) is fixedly connected with the plug head (4) after penetrating out of the push plate (33), and the push plate (33) is fixed on the slide (5) by a buckle assembly (6) when the push plate (33) moves to the rear end of the slide (5). A mounting portion (331) is arranged on the push plate (33) by bolt connection, and a mounting hole (332) for movably mounting the screw rod (2) is arranged in the mounting portion (331). The rack (1) is arranged in the slide (5), and the screw threads (21) on the screw rod (2) are engaged with the engaging tooth grooves (11) on the rack (1). The plug head (4) is mounted at the front and rear ends of the slide (5).

7. A propulsion mechanism according to claim 6, wherein The plug head (4) comprises a plug head body (41) and a movable block (42), movable grooves (411) for movably mounting the movable block (42) are arranged at the two sides of the plug head body (41), at least one protruding portion (421) is arranged on the surface of the movable block (42), and not less than one clamping portion (412) for grading the length of the movable groove (411) is arranged on the inner wall of the movable groove (411), the protruding portion (421) and the clamping portion (412) are clamped with each other, so that the movable block (42) can adjust the extension length of the movable block (42) in the movable groove (411) in multiple stages, and an insertion portion (422) for carrying a partition piece (43) is arranged at the end of the movable block (42) away from the plug head body (41), and the partition piece (43) is inserted in the insertion portion (422).

8. A propulsion mechanism according to claim 6, wherein, The slide (5) comprises a rack area (5A) for mounting the rack (1), a propelling area (5B) for slidingly mounting the propelling assembly (3), and a guiding area (5C) for guiding the sliding object.

9. A propulsion mechanism according to claim 8, wherein, The buckle assembly (6) comprises a first buckle (61) arranged at the rear end of the propelling area (5B) and a first clamping groove (62) arranged at the bottom of the push plate (33), when the push plate (33) moves to the rear end of the propelling area (5B), the first buckle (61) is clamped in the first clamping groove (62) to fix the push plate (33) at the rear end of the propelling area (5B).

10. A propulsion mechanism according to claim 8, wherein, The buckle assembly (6) comprises a second buckle (63) arranged at the rear end of the propelling area (5B) and a third buckle (64) arranged on the push plate (33), when the push plate (33) moves to the rear end of the propelling area (5B), the second buckle (63) is clamped in the third buckle (64) to fix the push plate (33) at the rear end of the propelling area (5B). The second buckle (63) comprises an L-shaped first clamping end, the third buckle (64) comprises a mounting buckle (641) fixedly arranged on the push plate (33) and a first clamping buckle (642) clamped in the mounting buckle (641), the first clamping buckle (642) comprises an L-shaped second clamping end, when the push plate (33) moves to the rear end of the propelling area (5B), the first clamping end extends into the first clamping buckle (642) to clamp the second clamping end.

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