Locking mechanism

Abstract

The utility model provides a locking mechanism which comprises a rotation limiting tooth arranged at the root position where any linkage piece is hinged to a back support and a locking piece controlled by a control switch, the locking piece is controlled to slide by toggling the control switch, and the locking piece is made to fill or move out of a gap formed between the rotation limiting tooth and the back support. Further, the rotary limiting teeth are propped against or separated from the locking piece; by means of the design, the chair back rail transfer mechanism can be locked in the reset state, and the application range of the chair back rail transfer mechanism is widened.

Description

Technical Field

[0001] The utility model relates to the field of seats, in particular to a locking mechanism for seats. Background Art

[0002] Chairs are an indispensable tool for home life and office environment. As people's living standards improve, they have higher and higher comfort requirements for chairs. For example, in addition to normal sitting, the backrests of some office chairs can also be rotated backwards, making the office chair have the function of a reclining chair.

[0003] For some reclining office chairs, a locking switch is provided on the chassis of the chair. With the control of the locking switch, the chair back can either stand upright to maintain a support state, or rotate backward around the chassis and switch to a reclining state. When the chair back rotates backward, the entire chair back falls backward. As a result, the front-to-back distance between the chair back and the seat will change when the chair back is reclining. When the seat position remains unchanged, the chair back and the user's back will undergo relative displacement and friction, causing discomfort. Thus, the so-called "back rubbing" problem occurs. The chair back of a conventional chair can only be adjusted in height in the vertical direction or in the front-to-back direction at most. However, the adjusted chair back is still in a fixed state, which results in not only the "back rubbing" problem during actual use of the chair back, but also the inability to effectively fit the user's back.

[0004] The applicant has now developed a chair back track changing mechanism, in which a track changing guide assembly is arranged between the back support and the backrest assembly, and the track changing guide assembly includes two linkage members spaced apart from each other. By hingedly connecting the backrest assembly, the back support and the track changing guide assembly, the backrest assembly, the back support and the track changing guide assembly form a four-bar structure, and an elastic member for resetting the four-bar structure is also arranged on the track changing mechanism; in this way, when the user's back leans backward to make the backrest assembly and the back support recline to an inclined state, the four-bar structure will be triggered to deform, and the elastic member will be elastically deformed. At this time, the backrest assembly moves forward and downward along the initial position under the guidance of the track changing guide assembly along with the back, thereby avoiding the "back rubbing" phenomenon and effectively forming a follow-up support for the back; when the user leaves the backrest assembly, the four-bar mechanism is reset under the action of the elastic member, and the backrest assembly is moved up to the initial position.

[0005] The backrest assembly will move downward synchronously with the back leaning back and provide support for the back; but when the backrest assembly is reset upward, if the user does not want to switch the seat to reclining mode, but just wants the backrest assembly in the initial state to provide stable support for the back, it is necessary to provide a locking mechanism on the seat back track changing mechanism. The locking mechanism should be able to lock the backrest assembly downward after it is reset upward, and can also unlock the locked backrest assembly, thereby expanding the scope of application of the seat back track changing mechanism. Summary of the invention

[0006] In order to solve the above-mentioned technical problems, the purpose of the utility model is to provide a locking mechanism, which controls the sliding of the locking piece by toggling a control switch, so that the locking piece fills or moves out of the gap formed between the rotation limit tooth and the back bracket, thereby making the rotation limit tooth abut against or separate from the locking piece; this design enables the chair back track changing mechanism to be locked in the reset state, thereby expanding the scope of application of the chair back track changing mechanism.

[0007] The technical solution of the utility model is achieved in this way:

[0008] A locking mechanism comprising:

[0009] The rotation limiting tooth is arranged at the root position of the hinge between any linkage member and the back bracket, and the rotation limiting tooth can rotate together with the corresponding linkage member; and a rotation gap is formed between the rotation limiting tooth and the back bracket;

[0010] A locking piece is slidably connected to the back bracket, and a control switch is connected to the locking piece. The control switch can control the locking piece to fill or move out of the rotation gap under external force.

[0011] The mechanism has a locked state and an unlocked state. When the mechanism is in the locked state, the control switch is toggled, and the locking piece can slide in and fill the rotation gap, so that the rotation limit tooth abuts against the locking piece and is limited; the control switch is toggled again, so that the locking piece slides out of the rotation gap and leaves rotation space for the rotation limit tooth, and the mechanism is switched to the unlocked state.

[0012] Preferably, the back support is provided with a slide groove which is recessed inwardly, and the locking piece slides in the slide groove. A pressure cover is provided at the opening of the slide groove, and the pressure cover restricts the locking piece in the slide groove and prevents the locking piece from escaping from the slide groove.

[0013] Preferably, the control switch includes a handle and a control rod, the junction of the control rod and the handle forms a rotating part rotatably connected to the back support, and an insertion rod is provided at the end of the control rod away from the rotating part; a waist-shaped groove is provided on the locking part, and the insertion rod is slidably connected in the waist-shaped groove; the handle is turned to rotate to drive the locking part to slide into or out of the rotating gap; the control switch is easy to be turned by external force, so that the user can control the backrest assembly to freely switch between the locked state and the unlocked state.

[0014] Preferably, a guide groove extending along the sliding direction of the locking member is provided on the end surface of the gland facing the locking member, and a guide bar is correspondingly provided on the end surface of the locking member facing the gland, and the guide bar is slidably connected in the guide groove. The guide bar cooperates with the guide groove to guide the locking member to slide in a predetermined direction.

[0015] Preferably, an arc-shaped avoidance groove corresponding to the rotation trajectory of the control rod is provided on the pressure cover, and the arc-shaped avoidance groove includes a starting end and an ending end. The insertion rod passes through the arc-shaped avoidance groove and is inserted into the waist-shaped groove, and switches between the starting end and the ending end under the linkage of the rotating part to drive the locking part to slide to fill or move out the rotation gap; when the arc-shaped avoidance groove avoids the rotation trajectory of the control rod, the starting end and the ending end can limit the swing range of the control rod, so that the locking part slides within a reasonable range.

[0016] Preferably, the control switch is an integrally formed open mold component; the open mold component is suitable for batch processing and production.

[0017] Preferably, the rotation angle range of the control rod is 20°-30°.

[0018] The principle and beneficial effects of the utility model using the above technical solution are:

[0019] The utility model provides a locking mechanism, which controls the sliding of a locking piece by toggling a control switch, so that the locking piece fills or moves out of a gap formed between a rotation limiting tooth and a back support, thereby making the rotation limiting tooth abut against or separate from the locking piece, thereby realizing locking or unlocking of a seat back track changing mechanism in a reset state by the locking mechanism, so that the seat back track changing mechanism in the reset state has two modes of downward movement and back chasing and locking support, thereby expanding the application range of the seat back track changing mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the backrest assembly when it is not moved downward;

[0021] Figure 2 is a schematic diagram of the backrest assembly after being moved downward;

[0022] Figure 3 This is an exploded view of the seat back track changing mechanism;

[0023] Figure 4 This is the exploded view of the locking module;

[0024] Figure 5 is an exploded diagram of the second linkage and the torsion spring;

[0025] Figure 6 is an enlarged view of the receiving groove on the back support;

[0026] Figure 7 is an enlarged view of the locking module installed in the receiving slot;

[0027] Figure 8 It is an enlarged view of the abutment between the rotation limit tooth and the limit surface;

[0028] Figure 9a It is a structural principle diagram of the hinged connection between the track change assembly and the back support and backrest assembly;

[0029] Figure 9b The schematic diagram is a schematic diagram of the backrest assembly moving forward and downward under the guidance of the track change assembly;

[0030] Fig.10a The structural diagram of the seat back track changing mechanism connected to the seat seat;

[0031] Fig.10b It is a schematic diagram of the structure in which the backrest assembly slides downward when the back support reclines;

[0032] Fig.11a Structural diagram of the control switch upper plug rod inserted into the waist-shaped groove;

[0033] Fig.11b This is a schematic diagram of the locking member before it enters the rotation gap;

[0034] Fig.11c It is the principle diagram after the locking member enters the rotation gap;

[0035] Fig.12a A schematic diagram of the structure of the rotation gap formed between the rotation limit groove and the limit surface;

[0036] Figure 12b A schematic diagram of the structure in which the locking member enters and fills the rotation gap;

[0037] Fig.13 The schematic diagram of the backrest assembly moving forward and downward driven by the track changing assembly in Example 2;

[0038] The reference numerals of the figures are: 1-back support, 2-backrest assembly, 3-first linkage member, 4-second linkage member, 5-torsion spring, 6-locking module, 7-rotating shaft, 8-seat, 11-second joint, 12-first joint, 13-torsion spring slot, 14-accommodating slot, 15-rotation support seat, 31-first rotating part, 32-first rotating arm, 41-second rotating part, 42-second rotating arm, 43-rotation limiting tooth, 44-jack, 61-control switch, 62-pressure cover, 63-locking member, 141-sliding groove, 142-installation groove, 611-insertion rod, 612-rotating member, 613-wrench, 614-control rod, 621-arc-shaped avoidance groove, 621a-starting end, 621b-terminating end, 622-guide groove, 631-waist-shaped groove, 632-guide strip, 633-limiting end surface, a-first hinge point, b-second hinge point, c-third hinge point. d-fourth hinge point, e-rotation gap, s-limiting surface. DETAILED DESCRIPTION

[0039] In order to more clearly understand the above-mentioned purpose, features and advantages of the utility model, the utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0040] In the description of the present invention, the term "at least one" refers to one or more than one, unless otherwise clearly defined. The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0042] The utility model has multiple embodiments, and the specific implementation methods are as follows:

[0043] Example 1: Figure 1-12b As shown, the utility model provides a locking mechanism, which is installed as a locking module 6 on the seat back track changing mechanism, and the seat back track changing mechanism includes:

[0044] A chair back assembly, comprising a back support 1 and a backrest assembly 2 arranged in front of the back support 1;

[0045] The track change guide assembly is arranged between the back support 1 and the backrest assembly 2, and includes a first linkage member 3 and a second linkage member 4 arranged at intervals in the upper and lower parts. The front and rear ends of the first linkage member 3 are directly hinged to the backrest assembly 2 and the back support 1 respectively, and the front and rear ends of the second linkage member 4 are directly hinged to the backrest assembly 2 and the back support 1, so that a four-link structure is formed between the back support 1, the backrest assembly 2, the first linkage member 3, and the second linkage member 4;

[0046] In the initial state, the backrest assembly 2 is in a higher position; when the backrest assembly 2 is triggered by a downward external force, it moves downward under the guidance of the track change guide assembly to switch to a lower position.

[0047] like Figure 1-2As shown, in the initial state, the first linkage member 3 extends forward or downward and is hinged to the upper end of the backrest assembly 2, and the second linkage member 4 extends forward and upward and is hinged to the lower end of the backrest assembly 2, thereby forming a trapezoidal four-link structure with a narrow front and a wide rear between the track change guide assembly and the seat back assembly; specifically, the rear end of the first linkage member 3 and the rear end of the second linkage member 4 are hinged to the back support 1, thereby forming a first hinge point a and a second hinge point b at the upper and lower ends of the back support 1 respectively; the first linkage member 3 extends forward or downward and is hinged to the upper end of the backrest assembly 2, and the second linkage member 4 extends forward and upward and is hinged to the lower end of the backrest assembly 2, thereby forming a third hinge point c and a fourth hinge point b at the upper and lower ends of the backrest assembly 2 respectively. Hinge point d; the distance between the third hinge point c and the fourth hinge point d is smaller than the distance between the first hinge point a and the second hinge point b, thereby forming a trapezoidal four-bar linkage structure that is narrow in front and wide in the back between the track change guide assembly and the chair back assembly; when the backrest assembly 2 is triggered by the downward external force, the trapezoidal four-bar linkage structure deforms and drives the backrest assembly 2 to move downward. At this time, the first linkage member 3 rotates downward, causing the third hinge point c to gradually approach the back bracket 1, and drives the upper end of the backrest assembly 2 to lean back, and the second linkage member 4 rotates downward, causing the fourth hinge point d to gradually move away from the back bracket 1, and drives the lower end of the backrest assembly 2 to move forward; the forward-moving backrest assembly 2 can form a chasing-back support for the back to avoid the phenomenon of the back being suspended in the air.

[0048] like Figure 3 , Figure 5 As shown, in order to keep the backrest assembly 2 stable when moving downward, the first linkage 3 includes a first rotating part 31 hinged to the back support 1, and the first rotating part 31 is connected to a left-right symmetrical first rotating arm 32, the second linkage 4 includes a second rotating part 41 hinged to the back support 1, and the second rotating part 41 is connected to a left-right symmetrical second rotating arm 42, the upper end of the back support 1 is provided with a first joint 12 hinged to the first rotating part 31, and the lower end of the back support 1 is provided with a second joint 11 hinged to the second rotating part 41, the first joint 12 and the second joint 11 are both provided with a rotating shaft 7, the front end of the first rotating arm 32 and the front end of the second rotating arm 42 are both hinged to the corresponding position of the backrest assembly 2, so that the track change guide assembly forms a rotation support for the left and right sides of the backrest assembly 2; this symmetrical structure forms a four-bar structure at both ends of the left and right ends of the backrest assembly 2, so that the left and right ends of the backrest assembly 2 can move up and down at the same time.

[0049] Furthermore, in order to enhance the forward movement effect of the lower end of the backrest assembly 2 and amplify the back-chasing effect of the backrest assembly 2, the length of the first rotating arm 32 is smaller than the length of the second rotating arm 42; the longer second rotating arm 42 has a larger rotation radius, which can increase the forward movement degree of the lower end of the backrest assembly 2, thereby making the back-chasing effect of the backrest assembly 2 more significant.

[0050] Furthermore, in order to make the backrest assembly 2 move downward more smoothly, and to ensure that the backrest assembly 2 can automatically reset upward when the external force is removed, an elastic member that can reset the four-bar structure after deformation is provided between the chair back assembly and the track change guide assembly, and the elastic member is caused to deform when the backrest assembly 2 is triggered and moves downward under the action of the downward external force; when the external force is removed, the track change guide assembly can rotate upward relative to the back support 1 under the action of the elastic member to reset the backrest assembly 2 upward; the elastic member can provide a reset elastic force for the deformation of the four-bar structure, so that the backrest assembly 2 can automatically reset upward to a higher position; specifically, the four-bar structure formed between the track change guide assembly and the chair back assembly has four hinge ends, namely a first hinge point a, a second hinge point b, a third hinge point c, and a fourth hinge point d, and the elastic member is arranged at at least one hinge point The torsion spring 5 at the end position; the number of the torsion spring 5 can be increased or decreased according to the use requirements. Under the premise of sufficient elastic force, the torsion spring 5 in this embodiment is only arranged between the second joint 11 and the second rotating part 41, wherein the torsion spring 5 is a double-arm torsion spring, the back support 1 is provided with a torsion spring slot 13 with a front end opening, the second rotating part 41 is provided with a socket 44 facing the torsion spring slot 13, and the lower end of the double-arm torsion spring is provided with a U-shaped connecting part, the U-shaped connecting part is stuck in the torsion spring slot 13, and the two elastic arms at the upper end of the double-arm torsion spring are inserted into the socket 44, thereby realizing the up and down elastic rotation of the second rotating part 41. When the second rotating part 41 rotates up and down elastically, the torsion spring 5 can provide elastic force for the reset of the four-bar structure. At the same time, the torsion spring 5 occupies a small space, which is convenient for hiding in the hinged end formed by the track change guide assembly and the chair back assembly, and will not affect the appearance of the entire chair back assembly.

[0051] like Figure 4-12b As shown, the chair back track changing mechanism also includes a locking module 6 arranged between the rotation limit tooth 43 and the limit surface s, and the locking module 6 includes a rotation limit tooth 43. The rotation limit tooth 43 can be set at the root position of any linkage and the back bracket 1 hinged, and can rotate with the corresponding linkage; and a rotation gap e is formed between the rotation limit tooth 43 and the back bracket 1; in this embodiment, only the example that the rotation limit tooth 43 can be set on the second rotating part 41 of the second linkage 4 is used for explanation.

[0052] Furthermore, the chair back assembly and the track change guide assembly form a four-bar structure. In order to ensure that the backrest assembly 2 can move up and down freely, the deformation of the four-bar structure should be kept within reasonable limits to avoid component collision or connecting rod jamming due to excessive deformation. A limiting surface s facing the rotation limit tooth 43 is provided at the front end of the back bracket 1; the limiting surface s is formed by a partial area of ​​the front end surface of the back bracket 1 being recessed inwardly. When the backrest assembly 2 moves downward into place, the rotation limit tooth 43 abuts against the limiting surface s; when the backrest assembly 2 is reset upward, the rotation limit tooth 43 is separated from the limiting surface s, and a rotation gap e is formed between the rotation limit tooth 43 and the limiting surface s; the design of the rotation limit tooth 43 and the limiting surface s can avoid excessive deformation of the four-bar structure, so that the backrest assembly 2 remains locked in position after being rotated downward into place, so that the backrest assembly 2 can still provide stable support for the back after moving downward.

[0053] like Figures 11a-12b As shown, the locking module 6 also includes a locking member 63, which is slidably connected to the back bracket 1. A control switch 61 is connected to the locking member 63. The control switch 61 can control the locking member 63 to fill or move out of the rotation gap e under the action of an external force; the mechanism has a locked state and an unlocked state. When the mechanism is in the locked state, the control switch 61 is turned, and the locking member 63 can slide in and fill the rotation gap e, so that the rotation limit tooth 43 is limited after abutting against the locking member 63; the control switch 61 is turned again, so that the locking member 63 slides out of the rotation gap e, and leaves rotation space for the rotation limit tooth 43, and the mechanism is switched to the unlocked state.

[0054] Further, the back support 1 is provided with a accommodating groove 14 with a front end opening, and the accommodating groove 14 includes an installation groove 142 opened in sequence from front to rear and a slide groove 141 recessed inwardly; the slide groove 141 is connected to the recessed area of ​​the limiting surface s; the locking module 6 includes a locking piece 63; the locking piece 63 includes a limiting end surface 633 facing the rotation limiting tooth 43, and the locking piece 63 slides in the slide groove 141; a pressure cover 62 is provided at the opening position of the slide groove 141, and the pressure cover 62 is in the installation groove 142, and limits the locking piece 63 in the slide groove to prevent the locking piece 63 from escaping from the slide groove 141; when the backrest assembly 2 moves upward to the initial position, a rotation gap e is formed between the rotation limiting tooth 43 and the limiting surface s, and the locking piece 63 can fill or give up the rotation gap e by sliding itself, so that the rotation limiting tooth 43 abuts against the locking piece 63 to be limited or leave a rotation gap The locking member 63 can be used to lock or unlock the downward movement of the backrest assembly 2; the locking module 6 can make the backrest assembly 2 move downward or lock downward according to actual needs, thereby expanding the application range of the chair back; that is, when the user needs to lock the backrest assembly 2 when the backrest assembly 2 is in a higher position so that it no longer moves downward, the locking member 63 can be pushed in and fill the rotation gap e, so that the limiting end face 633 abuts against the rotation limiting tooth 43. If the backrest assembly 2 does not need to be locked, it is not necessary to slide the locking member 63 into the rotation gap e; this design allows the user to adjust the position of the locking member 63 according to their own needs, so that the rotation limiting tooth 43 can selectively abut against the limiting end face 633. This design allows the backrest assembly 2 to have two supporting states, namely, locked and downward movement, in the reset state, thereby expanding the application range of the chair back.

[0055] Furthermore, the locking module 6 also includes a control switch 61, which is an integrally formed open mold part and is suitable for batch processing and production; the control switch 61 includes a handle 613 and a control rod 614, and the intersection of the control rod 614 and the handle 613 forms a rotating member 612 rotatably connected to the back bracket, the rotating member 612 is annular, and a rotating support seat 15 connected to the rotating member 612 is provided in the mounting groove 142, the rotating member 612 is connected to the rotating support seat 15 by screws, and the other end of the control rod 614 is connected to a plug rod 611; a waist-shaped groove 631 is provided on the locking member 63, and the plug rod 611 is slidably connected in the waist-shaped groove 631; the handle 613 is rotated to drive the locking member 63 to slide to reach the corresponding position; the control switch 61 is easy to be turned by external force, so that the user can control the locking or unlocking state of the backrest assembly 2; the control switch 61 is easy to be turned by external force, so that the user can control the backrest assembly 2 to switch between the locked state and the unlocked state.

[0056] Furthermore, a guide groove 622 extending along the sliding direction of the locking member 63 is provided on the end surface of the pressure cover 62 facing the locking member 63, and a guide bar 632 is correspondingly provided on the end surface of the locking member 63 facing the pressure cover 62, that is, the limiting end surface 633, and the guide bar 632 is slidably connected in the guide groove 622; the guide bar 632 cooperates with the guide groove 622 to play a sliding guiding role for the locking member 63, so that the locking member 63 fills or makes way for the rotation gap e.

[0057] Furthermore, the pressure cover 62 is provided with an arc-shaped avoidance groove 621 corresponding to the rotation trajectory of the control rod 614, and the arc-shaped avoidance groove 621 includes a starting end 621a and an ending end 621b. The insertion rod 611 passes through the arc-shaped avoidance groove 621 and is inserted into the waist-shaped groove 631, and switches between the starting end 621a and the ending end 621b under the linkage of the rotating member 612 to drive the locking member 63 to fill or make room for the rotation gap e; when the arc-shaped avoidance groove 621 avoids the rotation trajectory of the control rod 614, the starting end 621a and the ending end 621b can limit the swing range of the control rod 614, so that the locking member 63 slides within a reasonable range, thereby preventing the guide bar 632 from slipping out of the guide groove 622 due to excessive sliding range.

[0058] Furthermore, based on the actual sliding range of the locking member 63, the rotation angle range of the control rod 614 is generally 20°-30°, and correspondingly, the angle range between the two connecting lines formed by the starting end 621a and the ending end 621b of the arc-shaped avoidance groove 621 and the rotation center point of the control rod 614 is also 20°-30°.

[0059] like Figure 10a-10b As shown, a chair is provided, including a seat 8 and the seat back track changing mechanism, the lower end of the back support 1 is rotatably connected to the rear end of the seat 8, and the seat back assembly can lean back to a tilted state under the action of an external force and trigger the backrest assembly 2 at the same time, so that the backrest assembly 2 moves from a higher position to a lower position forward and downward; specifically, when the occupant's back leans back, the seat back assembly will lean back to a tilted state, and during the leaning back process, the back will move forward and downward, and the friction between the back and the backrest assembly 2 will also cause the backrest assembly 2 to move forward and downward, so that the backrest assembly can achieve adaptive tracking support for the back, effectively protecting the back and avoiding the phenomenon of the lower end of the back being suspended in the air.

[0060] Example 2: Fig.13As shown, the difference between this embodiment and embodiment 1 is that, in this embodiment, the lengths of the first rotating arm 31 and the second rotating arm 42 are the same. When the trapezoidal four-bar linkage structure is deformed and the backrest assembly 2 moves downward, it mainly relies on the front end of the first rotating arm 31 to pull the upper end of the backrest assembly 2 backward, and the front end of the second rotating arm 42 to pull the lower end of the backrest assembly 2 forward, so as to achieve the chasing effect of the backrest assembly 2. Therefore, the chasing effect of the backrest assembly 2 does not absolutely rely on the technical feature that the length of the first rotating arm 42 is greater than the length of the first rotating arm 31. When the lengths of the first rotating arm 31 and the second rotating arm 42 are the same, the backrest assembly 2 can also achieve the chasing effect in the above embodiment.

[0061] The above schematically describes the present invention and its implementation methods, which are not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. Therefore, if ordinary technicians in this field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A locking mechanism, characterized in that it comprises: A rotation limiting tooth (43) is arranged at the root position of a hinge between any linkage member and the back support (1); the rotation limiting tooth (43) can rotate together with the corresponding linkage member; and a rotation gap (e) is formed between the rotation limiting tooth (43) and the back support (1); A locking member (63) is slidably connected to the back support (1), and a control switch (61) is connected to the locking member (63). The control switch (61) can control the locking member (63) to fill or move out of the rotation gap (e) under the action of an external force; The mechanism has a locked state and an unlocked state. When the mechanism is in the locked state, the control switch (61) is toggled, and the locking member (63) can slide into and fill the rotation gap (e), so that the rotation limit tooth (43) abuts against the locking member (63) and is limited. The control switch (61) is toggled again, so that the locking member (63) slides out of the rotation gap (e), and a rotation space is reserved for the rotation limit tooth (43), and the mechanism is switched to the unlocked state.

2. A locking mechanism according to claim 1, characterized in that: The back support (1) is provided with a slide groove (141) which is recessed inwardly, and the locking member (63) slides in the slide groove (141). A pressure cover (62) is provided at the opening of the slide groove (141), and the pressure cover (62) restricts the locking member (63) in the slide groove (141).

3. A locking mechanism according to claim 2, characterized in that: The control switch (61) comprises a handle (613) and a control rod (614); the intersection of the control rod (614) and the handle (613) forms a rotating member (612) rotatably connected to the back support (1); an insertion rod (611) is provided at one end of the control rod (614) away from the rotating member (612); a waist-shaped groove (631) is provided on the locking member (63), and the insertion rod (611) is slidably connected in the waist-shaped groove (631); the handle (613) is turned to rotate, so as to drive the locking member (63) to slide into or out of the rotation gap (e).

4. A locking mechanism according to claim 2, characterized in that: A guide groove (622) extending along the sliding direction of the locking member (63) is provided on the end surface of the pressure cover (62) facing the locking member (63), and a guide bar (632) is correspondingly provided on the end surface of the locking member (63) facing the pressure cover (62), and the guide bar (632) is slidably connected in the guide groove (622).

5. A locking mechanism according to claim 3, characterized in that: The pressure cover (62) is provided with an arc-shaped avoidance groove (621) corresponding to the rotation trajectory of the control rod (614), and the arc-shaped avoidance groove (621) includes a starting end (621a) and an ending end (621b). The insertion rod (611) passes through the arc-shaped avoidance groove (621) and is inserted into the waist-shaped groove (631), and switches between the starting end (621a) and the ending end (621b) under the linkage of the rotating member (612), so as to drive the locking member (63) to slide, so as to fill or move out the rotation gap (e).

6. A locking mechanism according to claim 3, characterized in that: The control switch (61) is an integrally formed open mold component.

7. A locking mechanism according to claim 2, characterized in that: The rotation angle range of the control rod (614) is 20°-30°.

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