Back-chasing rail transfer mechanism and seat

Abstract

The utility model provides a chair back sliding orbital transfer mechanism and a seat, which comprise a back bracket and a backrest support piece arranged on the front side of the back bracket, a mounting seat is arranged between the backrest support piece and the back bracket, the mounting seat is connected on the back bracket in a sliding way along the longitudinal direction, and the upper end of the backrest support piece is hinged with the mounting seat to form a hinged end; an integrally-formed connecting part is arranged at the lower end of the backrest supporting piece, an integrally-formed matching part is arranged at the lower end of the back support, a rail transfer guide structure is arranged between the connecting part and the matching part and comprises a guide pin and a guide sliding groove which are matched with each other, and the guide sliding groove obliquely extends towards the lower front portion; according to the invention, the track guide of the backrest supporting piece is ensured, the lower end of the backrest supporting piece can be quickly mounted on the back bracket, the structure is simplified, the number of parts is reduced, and the assembly efficiency is improved; the sliding rail transfer mechanism is arranged on the seat, so that the manufacturing and maintenance cost of the seat can be effectively reduced, and the use experience of the seat is improved.

Description

Technical Field

[0001] The utility model relates to the field of seats, in particular to a backtracking and track-changing mechanism and a seat. Background Art

[0002] Most of the existing office chairs or ergonomic chairs have a reclining function. The backrest is rotatably connected to the seat chassis. After receiving a backward leaning force, the backrest can rotate backward. However, due to the height difference between the rotation point of the backrest and the backward rotation point of the human waist, it is difficult to coincide. On the premise that the seat position remains unchanged, relative displacement and friction will occur between the backrest and the user's back, resulting in discomfort; thus, the so-called "back rubbing" problem appears.

[0003] In the patent with the publication number of CN117297283A, the applicant designed a mechanism that can change the sliding track of the backrest. A sliding seat that can slide up and down on the backrest support and a rotating support member that is rotatably connected to both the backrest main body and the backrest support are provided between the backrest main body and the backrest support. When the sliding seat moves downward along the backrest support, the backrest main body rotates backward and the lower end of the backrest main body moves forward. The rotating support member rotates synchronously and guides the rotation track of the backrest main body, so that the backrest main body can also fit the back when rotating backward, avoiding the occurrence of back rubbing phenomenon. However, this design still has deficiencies.

[0004] 1. The track-changing and guiding backrest depends on the rotating support member. The rotating support member needs to be manufactured and installed separately, which increases the production and maintenance costs of the seat.

[0005] 2. During the assembly of the seat, the rotating support member needs to be hinged to the backrest support and the backrest main body respectively, which is time-consuming and laborious during installation, and the assembly efficiency is not high. Summary of the Invention

[0006] In order to solve the above technical problems, the purpose of the utility model is to provide a backtracking and track-changing mechanism. In this mechanism, the track-changing and adjusting structure provided between the backrest support and the backrest support is a guide pin and guide groove structure, which not only ensures the track guiding of the backrest support, but also enables the lower end of the backrest support to be quickly installed on the backrest support, simplifies the structure, saves the number of parts, and improves the assembly efficiency.

[0007] Furthermore, a seat is provided. By setting this sliding track-changing mechanism on the seat, the production and maintenance costs of the seat can be effectively reduced, and the use experience of the seat is improved.

[0008] The technical solution of the utility model is realized as follows:

[0009] A chasing-back rail-changing mechanism, comprising a back bracket and a backrest support member provided on the front side of the back bracket. An installation seat is provided between the backrest support member and the back bracket. The installation seat is slidably connected to the back bracket longitudinally. The upper end of the backrest support member is hinged to the installation seat to form a hinge end; the lower end of the backrest support member has an integrally formed connecting portion, and the lower end of the back bracket has an integrally formed matching portion. A rail-changing guiding structure is provided between the connecting portion and the matching portion. The rail-changing guiding structure includes a guide pin and a guiding chute that cooperate with each other. The guiding chute extends obliquely forward and downward; the guide pin is provided on one of the matching portion and the connecting portion, and the guiding chute is provided on the other of the matching portion and the connecting portion.

[0010] When the installation seat slides downward from an initial higher position to a lower position, the backrest support member rotates backward with the hinge end as the rotation center, and drives the rail-changing guiding structure to guide the rotation path of the backrest support member, so that the lower end of the backrest support member moves forward.

[0011] Preferably, the guiding chute is an arc-shaped chute extending obliquely forward and downward; when the upper end of the backrest support member rotates, its lower end has an arc-shaped rotation trajectory. Therefore, the arc-shaped chute can guide the backrest support member while adapting to the rotation trajectory of the backrest support member to prevent the backrest support member from getting stuck.

[0012] Preferably, the guiding chute is provided on the matching portion, and the guide pin is provided on the connecting portion; when the lower end of the backrest support member is matched with the back bracket, the guide pin on the connecting portion can be directly inserted into the guiding chute, which is simple and convenient to install and has a high assembly efficiency.

[0013] Preferably, the connecting portions are symmetrically arranged on both sides of the lower end of the backrest support member, and the matching portions are symmetrically arranged on both sides of the lower end of the back bracket and correspond to the positions of the connecting portions; so that the left and right sides of the backrest support member can be guided for rail-changing, ensuring the stability of the backrest support member.

[0014] Preferably, the matching portion is provided with ribs having the same extending direction as the guiding chute. When the guide pin slides in the guiding chute, the ribs contact the connecting portion and separate the connecting portion from the matching portion; preventing the matching portion from directly contacting the connecting portion and reducing the noise when the backrest support member changes its track.

[0015] Preferably, a first elastic member is provided between the installation seat and the back bracket. When the installation seat slides downward, the first elastic member deforms, and when the installation seat slides upward to reset, the first elastic member provides elastic force for the installation seat; making it easier for the backrest support member to reset.

[0016] Preferably, a hook portion is provided on the side of the installation seat facing the back bracket, and a hanging portion is provided on the side of the back bracket facing the installation seat. The first elastic member is a tension spring hooked on the hook portion and the hanging portion.

[0017] Preferably, the chair back is provided with a control locking mechanism disposed between the mounting seat and the back support, and the control locking mechanism can slide and lock and unlock the mounting seat at a higher position and a lower position, thereby expanding the application range of the chair back.

[0018] Preferably, the control locking mechanism comprises a locking member and a protrusion, the protrusion is arranged on the mounting seat, and the locking member is rotatably connected to the back bracket; the protrusion comprises a first wall surface and a second wall surface respectively located at the upper end and the lower end thereof, when the mounting seat is located at a lower position, the first wall surface corresponds to the position of the locking member, and when the mounting seat is located at a higher position, the second wall surface corresponds to the position of the locking member, and a driving component which can drive the locking member to tilt or reset after rotation is provided on the back bracket;

[0019] The control locking mechanism has an unlocking mode and a locking mode, and the locking modes include a first locking mode for locking the mounting seat in a lower position and a second locking mode for locking the mounting seat in a higher position; when the mounting seat slides downward from a higher position to a lower position, the control locking mechanism can be switched to the first locking mode, at which time the driving component can drive the locking piece to tilt up and press against the first wall surface, thereby limiting the mounting seat from sliding upward; when the control locking mechanism is switched to the unlocking mode, the driving component can control the locking piece to separate from the protruding portion, at which time the mounting seat can slide longitudinally; when the mounting seat is reset upward to a higher position, the control locking mechanism can be switched to the second locking mode, at which time the driving component can drive the locking piece to tilt up and press against the second wall surface, thereby limiting the mounting seat from sliding downward; based on the lever principle, the driving component can selectively act on the locking piece, so that the backrest support can switch between free sliding, high-position locking, and low-position locking, thereby meeting the various needs of the occupant and expanding the scope of application of the chair back.

[0020] Preferably, the driving assembly includes a movable rod and a driving control member acting on the movable rod. A guide bevel is provided on one end of the locking member facing the movable rod. The driving control member includes a crank rotatably connected to the back bracket, the crank is connected to the movable rod, and the crank is connected to a handle exposed on the back bracket. The handle is moved and the movable rod is driven to act or separate from the guide bevel, so that the locking member is tilted or reset, thereby controlling the locking mechanism to switch between a locking mode and an unlocking mode. When locking is required, the movable rod can act on the guide bevel to tilt the locking member. When unlocking is required, the movable rod can be separated from the guide bevel, and the locking member will return to its initial position. The design is simple and ingenious.

[0021] Preferably, a contact bevel is provided at one end of the movable rod facing the locking member, which is opposite to the guide bevel. By turning the handle, the contact bevel can act on or separate from the guide bevel. The contact bevel can make the movable rod and the locking member form surface contact, making the action between the movable rod and the locking member more stable.

[0022] Preferably, a convex block extending downward is provided at the opposite end of the locking member that tilts upward. A column corresponding to the position of the convex block is provided on the back bracket. When the locking member tilts upward and abuts against the first wall surface or the second wall surface, the convex block moves downward and abuts against the column to limit the further tilting of the locking member; this avoids unnecessary pressing on the mounting seat by the locking member due to an excessive tilting angle.

[0023] Preferably, a second elastic member is provided between the locking member and the back bracket. The second elastic member can provide an elastic force for the rotational reset of the locking member when the movable rod separates from the guiding inclined surface; this enables the locking member to stably return to its initial position and prevents the locking member from accidentally tilting upward in the unlocking mode, ensuring the usage experience of the chair back.

[0024] Preferably, a convex block extending downward is provided at the opposite end of the locking member that tilts upward. A column corresponding to the position of the convex block is provided on the back bracket. The second elastic member is a compression spring provided between the convex block and the column.

[0025] Furthermore, a seat is provided, including the described backtracking and variable track mechanism.

[0026] The beneficial effects of the present utility model adopting the above technical solutions are as follows:

[0027] 1. The variable track guiding structure of the present utility model adopts the design of a guide pin and a guide groove. The structural parts provided with the guide pin and the guide groove are respectively a mating part and a connecting part. These two structural components are integrally formed on the back bracket and the backrest support member respectively, without the need for separate manufacturing and installation. Compared with the design of using a rotating support member in the background technology patent, the present utility model reduces the installation complexity while ensuring the sliding variable track function. During installation, only the guide pin needs to be inserted into the guiding sliding groove, which not only improves the installation efficiency but also reduces the manufacturing and maintenance costs, enhancing the usage experience of the seat.

[0028] 2. The present utility model adopts a control locking mechanism. According to the different sitting requirements of the sitter, the mounting seat can be locked or unlocked. The control locking mechanism, based on the lever principle, enables the locking member rotatably connected to the back bracket to cooperate with the protrusion on the mounting seat accordingly, enabling the backrest support member to have an unlocked state with free movement, a high-position locked state in the initial position, and a low-position locked state during backtracking, expanding the applicable range of the seat and better meeting the sitting needs of users. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the mounting seat in a higher position;

[0030] Figure 2 It is a schematic diagram of the mounting seat in a lower position;

[0031] Figure 3 It is an exploded view of the backtracking and variable track mechanism;

[0032] Figure 4 The explosion diagram of the chasing-back and orbit-changing mechanism from another angle;

[0033] Figures 5a - 5b The schematic diagram for switching between the unlocking mode and the second locking mode in the control locking mechanism;

[0034] Figures 6a - 6b The schematic diagram for switching between the unlocking mode and the first locking mode in the control locking mechanism;

[0035] Figure 7 The enlarged view of the gland position;

[0036] Figure 8 The enlarged sectional view of the chasing-back and orbit-changing mechanism in the second locking mode;

[0037] Figure 9 The enlarged sectional view of the chasing-back and orbit-changing mechanism in the first locking mode;

[0038] Each reference numeral is: 1-back bracket, 2-mounting seat, 3-backrest support, 4-mating part, 5-control locking mechanism, 11-base, 11a-hanging part, 12-side chute, 13-rotating shaft hole, 14-accommodating groove, 15-swing limiting groove, 16-column, 17-compression spring, 18-compressing block, 21-protruding part, 22-first wall surface, 23-second wall surface, 24-hooking part, 31-connecting part, 41-guide pin, 42-guiding chute, 43-rib, 51-locking part, 52-movable rod, 53-crank, 54-handle, 55-cover plate, 151-limiting end face, 511-locking portion, 512-guiding inclined surface, 513-rotating shaft, 514-avoidance cavity, 515-protrusion, 521-contact inclined surface, 522-strip-shaped avoidance groove, 531-insert rod. Detailed implementation manners

[0039] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0040] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0041] The specific implementation manners of the present invention are as follows:

[0042] As Figures 1 - 9As shown in the figure, the utility model provides a backrest tracking and rail-changing mechanism, which includes a backrest support 1 and a backrest support member 3 arranged on the front side of the backrest support 1. An installation seat 2 is provided between the backrest support member 3 and the backrest support 1. The installation seat 2 is slidably connected to the backrest support 1 longitudinally. Specifically, a base 11 is provided on the front side of the backrest support 1. Longitudinally extending side chutes 12 are provided on both the left and right sides of the base 11. The installation seat 2 is connected with corresponding sliding rods, and the sliding rods are slidably connected in the side chutes 12. The upper end of the backrest support member 3 is hinged to the installation seat 2 to form a hinge end. The lower end of the backrest support member 3 has an integrally formed connecting portion 31, and the lower end of the backrest support 1 has an integrally formed mating portion 4. A rail-changing guiding structure is provided between the connecting portion 31 and the mating portion 4. The connecting portion 31 is symmetrically arranged on both sides of the lower end of the backrest support member 3, and the mating portion 4 is symmetrically arranged on both sides of the lower end of the backrest support 1 and corresponds to the position of the connecting portion 31. In this way, both the left and right sides of the backrest support member 3 can be guided for rail-changing, ensuring the stability of the backrest support member 3. The rail-changing guiding structure includes a cooperating guide pin 41 and a guiding chute 42. The guiding chute 42 extends obliquely forward and downward. The guide pin 41 is provided on one of the mating portion 4 and the connecting portion 31, and the guiding chute 42 is provided on the other of the mating portion 4 and the connecting portion 31.

[0043] When the backrest support 1 tilts backward under the backward leaning force of the sitter, and the installation seat 2 slides downward from the initial higher position to the lower position, the backrest support member 3 rotates backward with the hinge end as the rotation center, and drives the rail-changing guiding structure to guide the rotation path of the backrest support member 3, so that the lower end of the backrest support member 3 moves forward, thereby making the backrest support member 3 fit the human back better.

[0044] Furthermore, when the upper end of the backrest support member 3 rotates, its lower end has an arc-shaped rotation trajectory. Therefore, the guiding chute 42 is an arc-shaped chute extending obliquely forward and downward. The arc-shaped chute can guide the backrest support member 3 while adapting to the rotation trajectory of the backrest support member 3 to prevent the backrest support member 3 from jamming.

[0045] Furthermore, in this embodiment, for the convenience of installation, the guiding chute 42 is provided on the mating portion 4, and the guide pin 41 is provided on the connecting portion 31. When the lower end of the backrest support member 3 is mated with the backrest support 1, the guide pin 31 on the connecting portion 31 can be directly inserted into the guiding chute 42, which is simple and convenient to install and has a high assembly efficiency.

[0046] Furthermore, to ensure the use experience, the mating portion 4 is provided with ribs 43 having the same extending direction as the guiding chute 42. When the guide pin 41 slides in the guiding chute 42, the ribs 43 contact the connecting portion 31 and separate the connecting portion 31 from the mating portion 4, preventing the mating portion 4 from directly contacting the connecting portion 31, reducing the friction between the mating portion 4 and the connecting portion 31, and reducing the noise when the backrest support member 3 changes its track.

[0047] Furthermore, after the backrest receives a backward leaning force, the back support 1 reclines backward and triggers the track-changing guiding structure, causing the mounting seat 2 to slide from a higher position to a lower position. To facilitate the reset of the backrest support 3 and the mounting seat 2, a first elastic member is provided between the mounting seat 2 and the back support 1. When the mounting seat 2 slides downward, the first elastic member deforms, and when the mounting seat 2 slides upward to reset, the first elastic member provides elastic force for the mounting seat 2, making it easier to reset the backrest support 3. Specifically, a hook portion 24 is provided on one side of the mounting seat 2 facing the back support 1, and a hanging portion 11a is provided on one side of the back support 1 facing the mounting seat 2. The first elastic member is a tension spring (not shown) hooked on the hook portion 24 and the hanging portion 11a.

[0048] Furthermore, as Figures 5a - 9 shown, the mechanism further includes a control locking mechanism 5 provided between the mounting seat 2 and the back support 1. The control locking mechanism 5 can slide-lock and unlock the mounting seat 2 at higher and lower positions, thereby expanding the applicable range of the backrest. Specifically, the control locking mechanism 5 includes a locking member 51 and a protrusion 21. The protrusion 21 is provided on the mounting seat 2, and the locking member 51 is rotatably connected to the base 11 of the back support 1. The locking member 51 is a rod-shaped structure, and a locking portion 511 extending toward the protrusion 21 is provided on the locking member 51. The protrusion 21 includes a first wall surface 22 and a second wall surface 23 located at the upper and lower ends of itself respectively. When the mounting seat 2 is at the lower position, the first wall surface 22 corresponds to the locking member 51. When the mounting seat 2 is at the higher position, the second wall surface 23 corresponds to the locking member 51, and a driving assembly is provided on the back support 1 that can drive the locking member 51 to rotate and then tilt up or reset.

[0049] According to the usage requirements of the sitter, the control locking mechanism 5 has an unlocking mode and a locking mode. The locking mode includes a first locking mode for locking the mounting base 2 at a lower position and a second locking mode for locking the mounting base 2 at a higher position. Among them, the first locking mode is for the situation where after the backrest reclines, the sitter hopes to maintain the follow-back state of the backrest support 3 without resetting. The second locking mode is for the situation where the sitter only hopes the backrest to recline while the backrest support 3 remains at a higher position without follow-back. Specifically, when the mounting base 2 slides downward from a higher position to a lower position, the control locking mechanism 5 can be switched to the first locking mode. At this time, the driving component can drive the locking member 51 to tilt up, and make the locking portion 511 abut against the first wall surface 22 to restrict the upward sliding of the mounting base 2. When the control locking mechanism 5 is switched to the unlocking mode, the driving component can control the locking member 51 to separate from the convex portion 21. At this time, the mounting base 2 can slide longitudinally. When the mounting base 2 is reset upward to a higher position, the control locking mechanism 5 can be switched to the second locking mode. At this time, the driving component can drive the locking member 51 to tilt up, and make the locking portion 511 abut against the second wall surface 23 to restrict the downward sliding of the mounting base 2. According to the lever principle, the driving component can selectively act on the locking member 51, so that the backrest support 3 can be switched among free sliding, high-position locking, and low-position locking, which can meet the various needs of the sitter and expand the applicable range of the chair back.

[0050] Furthermore, a receiving groove 14 is formed on the base 11. The locking member 51 and the movable rod 52 are both arranged in the receiving groove 14, which saves the space occupied by the control locking mechanism 5. The locking member 51 is arranged in the receiving groove 14 in the following way: a rotating shaft hole 13 is formed on the side wall of the receiving groove 14. The locking member 51 has an integrally formed rotating shaft 513. For the convenience of installation, the rotating shaft hole 13 has a notch. The rotating shaft 513 can be placed into the rotating shaft hole 13 from the notch and is pressed by a pressing block 18 connected in the receiving groove 14. The side of the pressing block 18 pressing the rotating shaft 513 has an arc surface fitting the rotating shaft 513. In order to avoid the pressing block 18 during tilting or resetting, an avoidance cavity 514 corresponding to the position of the convex block 514 is provided on the locking member 51.

[0051] Furthermore, the specific structure of the driving component in this embodiment is as follows: the driving component includes a movable rod 52 and a driving control component that acts on the movable rod 52. A guiding inclined surface 512 is provided on the end of the locking component 51 that faces the movable rod 52. The driving control component includes a crank 53 that is rotatably connected to the back bracket 1, and a cover plate 55 that blocks the crank 53 and the movable rod 52 is connected to the back bracket 1; the crank 53 is connected to the movable rod 52, and a handle 54 exposed on the back bracket 1 is connected to the crank 53; the handle 54 is turned to drive the movable rod 52 to act on or separate from the guiding inclined surface 512, so that the locking component 51 is tilted or reset, thereby controlling the locking mechanism 5 to switch between the locking mode and the unlocking mode; when locking is required, the movable rod 52 can act on the guiding inclined surface 512 to tilt the locking component 51, and when unlocking is required, the movable rod 52 can be separated from the guiding inclined surface 512, and the locking component 51 will return to its initial position. The design is simple and ingenious, and easy to operate.

[0052] Furthermore, in order to ensure the control effect on the locking member 51, a contact bevel 521 is provided at one end of the movable rod 52 facing the locking member 51, which is opposite to the guide bevel 512. By turning the handle 54, the contact bevel 521 can be engaged or separated from the guide bevel 512; the contact bevel 521 can make the movable rod 52 and the locking member 51 form surface contact rather than line contact, so that the action between the movable rod 52 and the locking member 51 is smoother and more stable.

[0053] Furthermore, in the present embodiment, in order to ensure the locking effect, the reasonable angle range of the locking member 51 for rotating and tilting is 3°-15°. If the tilting angle exceeds 15°, it is easy for the locking portion 511 of the locking member 51 to hit the mounting seat 2, thereby affecting the use effect of the chair back. Therefore, in order to prevent the tilting angle of the locking member 51 from being too large, a downwardly extending protrusion 515 is provided at the opposite end of the tilted locking member 51, and a column 16 corresponding to the position of the protrusion 515 is provided on the back support 1. When the locking member 51 tilts upward and abuts against the first wall 22 or the second wall 23, the protrusion 515 moves downward and abuts against the column 16 to limit the locking member 51 from continuing to tilt, thereby avoiding unnecessary pressure on the mounting seat 2 by the locking member 51 due to the excessive tilting angle.

[0054] Furthermore, a second elastic member is provided between the locking member 51 and the back support 1, and the second elastic member is a compression spring 17 arranged between the protrusion 515 and the column 16; the second elastic member can provide the locking member 51 with elastic force for rotational restoration when the movable rod 52 is separated from the guide slope 512; so that the locking member 51 can stably return to the initial position, and prevent the locking member 51 from accidentally tilting upward in the unlocking mode, thereby ensuring the user experience of the chair back.

[0055] Furthermore, to ensure the flexibility of the crank 53 when acting on the movable rod 52, a plug rod 531 is provided on the crank 53, and a strip-shaped avoidance groove 522 corresponding to the position of the plug rod 531 is provided on the movable rod 52. The plug rod 531 is inserted into the strip-shaped avoidance groove 522. When the crank 53 rotates, the plug rod 531 can drive the movable rod 52 to move, and at the same time, the strip-shaped avoidance groove 522 can avoid the plug rod 531. While ensuring that the crank 53 can drive the movable rod 52 to act on the locking member 51, it can also prevent jamming between the crank 53 and the movable rod 52.

[0056] Furthermore, when the handle 54 is toggled by forces of different magnitudes, its rotation angle is also different. Different rotation angles will affect the locking and unlocking effects of the locking member 51 on the mounting base 2. Therefore, a swing limit groove 15 is provided on the base 11. The swing limit groove 15 has two opposite limit end faces 151. The handle 54 rotates between the two opposite limit end faces 151, controlling the toggling range of the handle 54 and enabling the control locking mechanism 5 to stably switch between the locking mode and the unlocking mode.

[0057] Furthermore, a seat is provided, including the above-mentioned backrest variable track mechanism. On the premise of ensuring the sliding variable track function, the installation complexity is reduced. During installation, only the guide pin 41 needs to be inserted into the guide chute 43, which not only improves the installation efficiency, reduces the manufacturing and maintenance costs, but also enhances the seat usage experience.

[0058] The above schematically describes the present invention and its implementation manners. This description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and, without departing from the creative concept of the present invention, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A track-changing mechanism, characterized by: The invention comprises a back support (1) and a back support member (3) arranged at the front side of the back support (1); a mounting seat (2) is arranged between the back support member (3) and the back support (1); the mounting seat (2) is slidably connected to the back support (1) in the longitudinal direction; the upper end of the back support member (3) is hinged to the mounting seat (2) to form a hinged end; the lower end of the back support member (3) has an integrally formed connecting portion (31); the lower end of the back support (1) has an integrally formed matching portion (4); a track change guide structure is arranged between the connecting portion (31) and the matching portion (4); the track change guide structure comprises a guide pin (41) and a guide slot (42) which match each other; the guide slot (42) extends obliquely forward and downward; the guide pin (41) is arranged on one of the matching portion (4) and the connecting portion (31); the guide slot (42) is arranged on the other of the matching portion (4) and the connecting portion (31); When the mounting seat (2) slides downward from an initial higher position to a lower position, the backrest support member (3) rotates backward with the hinged end as the rotation center, and drives the track change guide structure to guide the rotation path of the backrest support member (3), so that the lower end of the backrest support member (3) moves forward.

2. The track-changing mechanism according to claim 1, characterized in that: The guide slide groove (42) is an arc-shaped groove extending obliquely forward and downward.

3. The track-changing mechanism according to claim 1 is characterized in that: The guide slot (42) is arranged on the matching portion (4), and the guide pin (41) is arranged on the connecting portion (31).

4. The track-changing mechanism according to claim 1, characterized in that: The connecting portion (31) is symmetrically arranged on both sides of the lower end of the backrest support (3), and the matching portion (4) is symmetrically arranged on both sides of the lower end of the back support (1) and corresponds to the position of the connecting portion (31).

5. The track-changing mechanism according to claim 1 is characterized in that: The matching portion (4) is provided with a rib (43) extending in the same direction as the guide slot (42); when the guide pin (41) slides in the guide slot (42), the rib (43) contacts the connecting portion (31) and separates the connecting portion (31) from the matching portion (4).

6. The track-changing mechanism according to claim 1, characterized in that: A first elastic member is provided between the mounting seat (2) and the back support (1); when the mounting seat (2) slides downward, the first elastic member is deformed; when the mounting seat (2) slides upward to reset, the first elastic member provides elastic force for the mounting seat (2).

7. The track-changing mechanism according to claim 6, characterized in that: A hook portion (24) is provided on the side of the mounting seat (2) facing the back bracket (1), and a hanging portion (11a) is provided on the side of the back bracket (1) facing the mounting seat (2). The first elastic member is a tension spring hooked on the hook portion (24) and the hanging portion (11a).

8. The track-changing mechanism according to claim 1, characterized in that: It also comprises a control locking mechanism (5) arranged between the mounting seat (2) and the back support (1), and the control locking mechanism (5) can slide and lock and unlock the mounting seat (2) in a higher position and a lower position.

9. The track-changing mechanism according to claim 8, characterized in that: The control locking mechanism (5) comprises a locking member (51) and a protrusion (21), wherein the protrusion (21) is arranged on the mounting seat (2), and the locking member (51) is rotatably connected to the back support (1); the protrusion (21) comprises a first wall surface (22) and a second wall surface (23) respectively located at the upper end and the lower end thereof; when the mounting seat (2) is located at a lower position, the first wall surface (22) corresponds to the position of the locking member (51); when the mounting seat (2) is located at a higher position, the second wall surface (23) corresponds to the position of the locking member (51); and a driving component capable of driving the locking member (51) to rotate and then tilt or reset is provided on the back support (1); The control locking mechanism (5) has an unlocking mode and a locking mode, the locking mode comprising a first locking mode for locking the mounting seat (2) at a lower position and a second locking mode for locking the mounting seat (2) at a higher position; when the mounting seat (2) slides downward from a higher position to a lower position, the control locking mechanism (5) can be switched to the first locking mode, at which time the driving component can drive the locking member (51) to tilt up and abut against the first wall surface (22), thereby limiting the mounting seat (2) from sliding upward; When the locking mechanism (5) is controlled to switch to an unlocking mode, the driving component can control the locking member (51) to separate from the protruding portion (21), and the mounting seat (2) can slide in the longitudinal direction; when the mounting seat (2) is reset upward to a higher position, the locking mechanism (5) can be controlled to switch to a second locking mode, and the driving component can drive the locking member (51) to tilt up and abut against the second wall surface (23), thereby limiting the mounting seat (2) from sliding downward.

10. The track-changing mechanism according to claim 9, characterized in that: The driving assembly comprises a movable rod (52), a driving control member acting on the movable rod (52), a guiding inclined surface (512) being provided on one end of the locking member (51) facing the movable rod (52), and the driving control member comprises a crank (53) rotatably connected to the back support (1), the crank (53) being connected to the movable rod (52), and a handle (54) exposed on the back support (1) being connected to the crank (53); the handle (54) is moved to drive the movable rod (52) to act on or separate from the guiding inclined surface (512), so that the locking member (51) is tilted or reset, thereby controlling the locking mechanism (5) to switch between a locking mode and an unlocking mode.

11. The track-changing mechanism according to claim 10, characterized in that: One end of the movable rod (52) facing the locking member (51) is provided with a contact inclined surface (521) opposite to the guide inclined surface (512). The contact inclined surface (521) can be engaged with or separated from the guide inclined surface (512) by rotating the handle (54).

12. The track-changing mechanism according to claim 9, characterized in that: A protrusion (515) extending downward is provided at the opposite end of the tilted locking member (51), and a column (16) corresponding to the position of the protrusion (515) is provided on the back support (1). When the locking member (51) tilts upward and abuts against the first wall surface (22) or the second wall surface (23), the protrusion (515) moves downward and abuts against the column (16) to limit the locking member (51) from continuing to tilt.

13. The track-changing mechanism according to claim 9, characterized in that: A second elastic member is provided between the locking member (51) and the back support (1), and the second elastic member can provide elastic force for the locking member (51) to rotate and reset when the movable rod (52) is separated from the guiding inclined surface (512).

14. The track-changing mechanism according to claim 13, characterized in that: A downwardly extending protrusion (515) is provided at the opposite end of the tilted locking member (51), a column (16) corresponding to the position of the protrusion (515) is provided on the back support (1), and the second elastic member is a compression spring (17) arranged between the protrusion (515) and the column (16).

15. A seat, characterized in that: It includes the track-chasing and track-changing mechanism described in claim 1.

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