CN220916980U - Backrest mechanism and seat iron frame - Google Patents

Abstract

The utility model relates to the technical field of seats, and particularly discloses a backrest mechanism and a seat iron frame, wherein the backrest mechanism comprises a four-bar linkage and a driving piece, the four-bar linkage comprises a first connecting bar, a second connecting bar, a third connecting bar and a fourth connecting bar which are sequentially hinged and are arranged in a surrounding manner, the driving piece is arranged on a suspension mechanism and is connected with the four-bar linkage, and a seat frame bracket can move relative to the suspension mechanism along a preset direction so that the driving piece can drive the four-bar linkage to change the shape; in the process of changing the shape of the four-bar linkage, the moving distance of the hinge point of the third connecting bar and the fourth connecting bar is 60mm-100mm. Through setting up the distance that the pin joint of third connecting rod and fourth connecting rod moved, and then can adjust the angle and the position of back, owing to be connected through four link group between back and the seat frame, consequently, can solve back and wall distance too near, can meet back and wall and take place the motion interference, and then can't realize the problem that each mode of seat iron stand switches smoothly.

Description

Backrest mechanism and seat iron frame

Technical Field

The utility model relates to the technical field of seats, in particular to a backrest mechanism and a seat iron frame.

Background

With the development of society, people are increasingly pursuing quality of life. For the choice of furniture, consumers have not been limited to a single function, and more so, it is the modern thinking that it is desirable to maximize the utilization of the furniture. Such as seats or sofas, consumers are more in pursuit of comfort, such as the ability to provide a variety of modes of use, such as reading, lying down, etc., while as research and development continues, functional sofas are also available on the market, but these sofas still suffer from deficiencies in multi-mode use.

If the backrest and the wall are too close to each other when the sofa is placed against the wall, the backrest and the wall are interfered in movement, so that the sofa mode can not be smoothly switched.

Disclosure of utility model

The utility model aims at: the backrest mechanism and the seat iron frame are provided to solve the problem that in the related art, if the backrest is too close to the wall, the backrest and the wall of the sofa are involved in movement interference, and therefore the smooth switching of each mode of the sofa cannot be realized.

In one aspect, the present utility model provides a back rest mechanism for a seat iron comprising a suspension mechanism and a frame support hinged thereto, the back rest mechanism comprising:

the seat frame support can move relative to the suspension mechanism along a preset direction, so that the driving piece can drive the four-bar set to change the shape;

In the process of changing the shape of the four-bar linkage, the moving distance of the hinge point of the third connecting bar and the fourth connecting bar is 60mm-100mm.

As the preferable technical scheme of the backrest mechanism, the first connecting rod is fixedly connected with the seat frame support, and the driving piece drives the second connecting rod to rotate around the hinge point of the second connecting rod and the first connecting rod.

As a preferable technical scheme of the backrest mechanism, the second connecting rod is hinged with one end of the first connecting rod and one end of the third connecting rod respectively; the fourth connecting rod is positioned on one side of the second connecting rod and is hinged with one end, away from the second connecting rod, of the first connecting rod and one end, away from the second connecting rod, of the third connecting rod respectively.

As the preferable technical scheme of the backrest mechanism, the driving piece is a driving rod, one end of the driving rod is hinged with the suspension mechanism, one end of the second connecting rod is hinged with the third connecting rod, the other end of the second connecting rod is hinged with the other end of the driving rod, and the middle part of the second connecting rod is hinged with the first connecting rod.

As a preferable technical scheme of the backrest mechanism, the third connecting rod is provided with a first limiting protrusion, the first limiting protrusion is positioned between the second connecting rod and the fourth connecting rod, the first connecting rod is provided with a second limiting protrusion, and the second limiting protrusion is positioned at one side of the fourth connecting rod far away from the second connecting rod;

the first limiting protrusion and the second limiting protrusion are alternatively abutted against the fourth connecting rod.

As a preferable technical scheme of the backrest mechanism, in the process of changing the shape of the four-bar linkage, the moving distance of the hinge point of the third connecting bar and the fourth connecting bar is 70mm-95mm.

As the preferable technical scheme of the backrest mechanism, in the process of changing the shape of the four-bar linkage, the moving distance of the hinge point of the third connecting bar and the fourth connecting bar is 80mm-85mm.

On the other hand, the utility model also provides a seat iron frame, which comprises the backrest mechanism in any one of the schemes, and the seat iron frame further comprises:

A suspension mechanism;

A seat frame bracket; is hinged with the suspension mechanism;

The seat frame support can move relative to the suspension mechanism along the preset direction, so that the driving piece can drive the four-bar linkage to change the shape.

As the preferred technical scheme of seat iron stand, still include pedal telescopic machanism, pedal telescopic machanism set firmly in seat frame support just includes extension pole group, main pedal and vice pedal subassembly, extension pole group drives main pedal with vice pedal subassembly is relative seat frame support extends or withdraws.

As the preferable technical scheme of seat iron stand, the extension rod group includes first extension rod, second extension rod, third extension rod and fourth extension rod, first extension rod with the second extension rod articulates, the third extension rod with the fourth extension rod articulates, the middle part of first extension rod with the middle part cross hinge of fourth extension rod, first extension rod with the third extension rod respectively with seat frame support articulates, second extension rod with the fourth extension rod respectively with main pedal articulates.

As the preferable technical scheme of the seat iron frame, the auxiliary pedal assembly comprises an auxiliary pedal and an auxiliary connecting rod, two ends of the auxiliary connecting rod are respectively hinged with the auxiliary pedal and the main pedal, and the middle part of the second stretching rod is hinged with the main pedal; one end of the second extending rod far away from the first extending rod is hinged with the auxiliary pedal.

As the preferable technical scheme of the seat iron frame, the suspension mechanism comprises a first rod, a second rod and a third rod, wherein the first rod, the second rod, the third rod and the seat frame support are sequentially hinged end to end and are enclosed into a first annular four-bar structure;

The suspension mechanism further comprises a fourth rod, a fifth rod, a sixth rod and a seventh rod, wherein the middle part of the fourth rod is hinged with one end of the fifth rod, the other end of the fifth rod is hinged with one end of the sixth rod, the other end of the sixth rod is hinged with the middle part of the seventh rod, one end of the seventh rod is hinged with one end of the fourth rod, and the fourth rod, the fifth rod, the sixth rod and the seventh rod are enclosed to form a second annular four-bar structure;

The suspension mechanism further comprises a first connecting rod and a second connecting rod, the first connecting rod comprises a first connecting supporting rod and a second connecting supporting rod, one end of the first connecting supporting rod is hinged to the other end of the fourth rod, the other end of the first connecting supporting rod is hinged to the middle of the second rod, one end of the second connecting supporting rod is hinged to the middle of the fourth rod, the second rod is hinged to the hinged end of the first rod and the other end of the second connecting supporting rod, one end of the second connecting rod is hinged to the middle of the sixth rod, and the other end of the second connecting rod is hinged to the second rod.

As the preferable technical scheme of seat iron stand, still include the trace, the one end of trace with the third extension pole is articulated, the other end of trace with the third pole is articulated, the trace with the pin joint of third extension pole with the pin joint interval of third extension pole with seat frame support is 22mm-26mm, the interval of two pin joints at third extension pole both ends is 18cm-22cm.

The beneficial effects of the utility model are as follows:

The utility model provides a backrest mechanism and a seat iron frame, wherein the backrest mechanism comprises a four-bar linkage and a driving piece, the four-bar linkage comprises a first connecting bar, a second connecting bar, a third connecting bar and a fourth connecting bar which are sequentially hinged and are arranged in a surrounding manner, the driving piece is arranged on a hanging mechanism and is connected with the four-bar linkage, and a seat frame bracket can move relative to the hanging mechanism along a preset direction so that the driving piece can drive the four-bar linkage to change the shape; in the process of changing the shape of the four-bar linkage, the moving distance of the hinge point of the third connecting bar and the fourth connecting bar is 60mm-100mm. When the seat iron frame provided with the backrest mechanism is used for adjusting a seat mode, the driving piece can drive the four-bar linkage to change the shape in the process of moving the seat frame support along the preset direction relative to the suspension mechanism, so that the angle and the relative position of the backrest and the ground can be changed, the shape of the seat iron frame can be further changed, and particularly, the change of the angle and the position of the backrest relative to the ground is determined by the moving distance of the hinge point of the third bar linkage and the fourth bar linkage in the process of changing the shape of the four-bar linkage. The backrest is connected with the seat frame through the four-bar linkage, so that the problem that the backrest is too close to the wall, the backrest and the wall are involved in motion interference, and the smooth switching of modes of the seat iron frame cannot be realized is solved.

Drawings

FIG. 1 is a schematic view of a seat iron frame in a sitting posture mode according to a first embodiment of the present utility model;

FIG. 2 is a schematic diagram of a sitting posture mode of a seat iron frame according to a first embodiment of the present utility model;

FIG. 3 is a schematic view showing a TV mode of a seat iron stand according to a first embodiment of the present utility model;

FIG. 4 is a schematic diagram of a TV mode of a seat iron stand according to a first embodiment of the present utility model;

FIG. 5 is a schematic view of a first embodiment of a seat iron in a recumbent mode;

fig. 6 is a schematic diagram of a second structure of a recumbent mode of the seat iron stand according to the first embodiment of the present utility model;

fig. 7 is a schematic diagram of a sitting posture mode of a seat iron stand according to a second embodiment of the present utility model.

In the figure:

1. A suspension mechanism; 11. a first lever; 12. a second lever; 13. a third lever; 14. a fourth lever; 15. a fifth lever; 16. a sixth lever; 17. a seventh lever; 18. a first connecting rod; 19. a second connecting rod;

2. A seat frame bracket;

3. A backrest mechanism; 31. a four bar linkage; 311. a first link; 3111. the second limiting bulge; 312. a second link; 313. a third link; 3131. the first limiting protrusion; 314. a fourth link; 32. a driving member;

4. A pedal telescoping mechanism; 41. an extension bar set; 411. a first extension bar; 412. a second extension rod; 413. a third extension bar; 414. a fourth extension bar; 42. a main pedal; 43. an auxiliary pedal assembly; 431. auxiliary pedals; 432. a secondary connecting rod;

5. and a linkage rod.

Detailed Description

The following description of the embodiments of the present utility model will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the utility model are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the present utility model, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are directions or positional relationships based on the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements to be referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first location" and "second location" are two distinct locations and wherein the first feature is "above," "over" and "over" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is level above the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the utility model.

Example 1

As shown in fig. 1 to 6, the present embodiment provides a seat iron frame including a suspension mechanism 1, a seat frame bracket 2, and a backrest mechanism 3, the seat frame bracket 2 being hinged with the suspension mechanism 1; the backrest mechanism 3 comprises a four-bar linkage 31 and a driving piece 32, wherein the four-bar linkage 31 comprises a first connecting bar 311, a second connecting bar 312, a third connecting bar 313 and a fourth connecting bar 314 which are sequentially hinged and are arranged in an encircling mode, the first connecting bar 311 is fixedly connected with the seat frame support 2, the first connecting bar 311 and the seat frame support 2 can be fixedly connected through a plurality of screws or rivets, the driving piece 32 can be integrally formed, the driving piece 32 is arranged on the hanging mechanism 1 and is connected with the second connecting bar 312, the seat frame support 2 can move relative to the hanging mechanism 1 along a preset direction, and the driving piece 32 can drive the second connecting bar 312 to rotate around a hinge point of the second connecting bar 312 and the first connecting bar 311. The seat modes of the seat iron frame comprise a sitting posture mode, a TV mode and a lying posture mode, and when the seat iron frame is adjusted from the sitting posture mode to the TV mode, the angle relation among the connecting rods of the backrest mechanism 3 is almost unchanged in the process of driving the seat frame bracket 2 to move relative to the hanging mechanism 1 along the preset direction, and the backrest mechanism 3 slightly moves forwards along with the seat frame bracket 2, so that a gap exists between a backrest arranged on the backrest mechanism 3 and a wall. When the TV mode is adjusted to the lying mode, the seat frame support 2 continues to move forward and slightly lifts upwards, the driving piece 32 can drive the second connecting rod 312 to swing around the hinging point, and then the shape of the four-bar linkage 31 enclosed by the first connecting rod 311, the second connecting rod 312, the third connecting rod 313 and the fourth connecting rod 314 is changed, in the process, the included angle and the relative position between the third connecting rod 313 and the ground are continuously changed, the distance between the top point of the third connecting rod 313 and the wall is reduced, and the distance between the backrest arranged on the backrest mechanism 3 and the wall is infinitely close to 0. The third connecting rod 313 is connected with the backrest, so that the process can change the angle between the backrest and the ground, and the form of the iron frame of the seat can be switched, and the backrest is connected with the seat frame through the four-bar linkage 31, so that the problem that the backrest is too close to the wall, the backrest and the wall are interfered in movement, and the smooth switching of modes of the iron frame of the seat cannot be realized can be solved.

Alternatively, the hinge point of the third link 313 and the fourth link 314 moves by a distance of 60mm to 100mm during the change of the shape of the four-bar linkage 31. The distance the hinge point moves determines the angle and position of the backrest relative to the ground. In other embodiments, the hinge point of the third link 313 and the fourth link 314 may also move a distance of 70mm-95mm or 80mm-85mm.

Specifically, the seat frame bracket 2 is used for mounting a seat frame. The seat iron frame can be applied to sofas, wheelchairs, saddles and the like.

Alternatively, the second link 312 is hinged to one end of the first link 311 and one end of the third link 313, respectively; the fourth link 314 is located at one side of the second link 312 and is hinged to one end of the first link 311 away from the second link 312 and one end of the third link 313 away from the second link 312, respectively. The driving member 32 includes a driving rod having one end hinged to the suspension mechanism 1, one end of the second link 312 hinged to the third link 313, the other end hinged to the other end of the driving rod, and a middle portion of the second link 312 hinged to the first link 311. In this embodiment, the driving rod drives the other end of the second link 312 to move, so that the second link 312 rotates around the first link, and the angle and the relative position between the third link 313 and the ground are changed.

Specifically, the second link 312 is bent at a circular intersection with the first link 311, and the bending angle is an obtuse angle.

Optionally, the suspension mechanism 1 includes a first rod 11, a second rod 12 and a third rod 13, where the first rod 11, the second rod 12, the third rod 13 and the seat frame support 2 are hinged end to end in sequence and enclose a first annular four-bar structure. In this embodiment, the first rod 11, the second rod 12, the third rod 13 and the seat frame support 2 are enclosed to form an annular four-bar structure, and the seat frame support 2 can move relative to the second rod 12 along a preset direction.

Optionally, the suspension mechanism 1 further includes a fourth rod 14, a fifth rod 15, a sixth rod 16 and a seventh rod 17, where the middle part of the fourth rod 14 is hinged with one end of the fifth rod 15, the other end of the fifth rod 15 is hinged with one end of the sixth rod 16, the other end of the sixth rod 16 is hinged with the middle part of the seventh rod 17, one end of the seventh rod 17 is hinged with one end of the fourth rod 14, and the fourth rod 14, the fifth rod 15, the sixth rod 16 and the seventh rod 17 are enclosed to form a second annular four-bar structure; the suspension mechanism 1 further comprises a first connecting rod 18 and a second connecting rod 19, the first connecting rod 18 comprises a first connecting strut 181 and a second connecting strut 182, one end of the first connecting strut 181 is hinged with the other end of the fourth rod 14, the other end of the first connecting strut 181 is hinged with the middle part of the second rod 12, one end of the second connecting strut 182 is hinged with the middle part of the fourth rod 14, the hinged end of the second rod 12 and the first rod 11 is hinged with the other end of the second connecting strut 182, one end of the second connecting rod 19 is hinged with the middle part of the sixth rod 16, and the other end of the second connecting rod 19 is hinged with the second rod 12. In the present embodiment, the second ring-shaped four-bar linkage composed of the fourth bar 14, the fifth bar 15, the sixth bar 16 and the seventh bar 17 is hinged to the four-bar linkage 31, specifically, the driving bar is hinged to the other end of the seventh bar 17.

Optionally, the seat iron stand further comprises a pedal telescopic mechanism 4, wherein the pedal telescopic mechanism 4 comprises an extension rod group 41, a main pedal 42 and an auxiliary pedal assembly 43, and the extension rod group 41 drives the main pedal 42 and the auxiliary pedal assembly 43 to extend or retract relative to the seat frame support 2. In this embodiment, when the main pedal 42 and the auxiliary pedal assembly 43 are in the extended position, a person sitting on the seat can rest his feet on the main pedal 42 and the auxiliary pedal assembly 43, so that the comfort of the person sitting on the seat can be improved.

Specifically, the extension bar group 41 includes a first extension bar 411, a second extension bar 412, a third extension bar 413, and a fourth extension bar 414, the first extension bar 411 is hinged to the second extension bar 412, the third extension bar 413 is hinged to the fourth extension bar 414, the middle portion of the first extension bar 411 is hinged to the middle portion of the fourth extension bar 414, the first extension bar 411 and the third extension bar 413 are respectively hinged to the seat frame bracket 2, and the second extension bar 412 and the fourth extension bar 414 are respectively hinged to the main pedal 42. In this embodiment, by rotating the first extension rod 411 relative to the seat frame support 2, it is further achieved that the extension rod set 41 drives the main pedal 42 and the sub pedal assembly 43 to extend or retract relative to the seat frame support 2.

Alternatively, the auxiliary pedal assembly 43 includes an auxiliary pedal 431 and an auxiliary link 432, both ends of the auxiliary link 432 are respectively hinged with the auxiliary pedal 431 and the main pedal 42, and the middle part of the second extension rod 412 is hinged with the main pedal 42; the end of the second expansion link 412 remote from the first expansion link 411 is hinged to the sub pedal 431. In the present embodiment, when the main pedal 42 is switched to the extended state, the second extending rod 412 drives the auxiliary pedal 431 to move, so that the auxiliary pedal 431 and the main pedal 42 are both in the extended state.

Optionally, the seat iron stand further comprises a driver, the driver is fixedly connected with the seventh rod 17, and the telescopic end of the driver is hinged with the first stretching rod 411, and the telescopic end of the driver stretches along a preset direction. In this embodiment, the telescopic end of the actuator is hinged to the first extension rod 411, and then the first extension rod 411 is driven to rotate around the seat frame support 2, so that the seat frame support 2 is driven to move along a preset direction.

Alternatively, the hanging mechanism 1, the backrest mechanism 3 and the pedal telescopic mechanism 4 are all provided with two, the two hanging mechanisms 1 are arranged at intervals and symmetrically along the vertical preset direction, the two backrest mechanisms 3 are arranged at intervals and symmetrically along the vertical preset direction, the two pedal telescopic mechanisms 4 are arranged at intervals and symmetrically along the vertical preset direction, the seat frame support 2 is arranged between the two hanging mechanisms 1, and two sides of the seat frame support 2 are respectively hinged with the first rod 11 and the third rod 13 of the two hanging mechanisms 1. The backrest is arranged between the two backrest mechanisms 3, and two sides of the backrest are respectively fixedly connected with two third connecting rods 313.

Optionally, the seat iron stand further comprises a linkage rod 5, one end of the linkage rod 5 is hinged with the third extension rod 413, the other end of the linkage rod 5 is hinged with the third rod 13, the distance between the hinge point of the linkage rod 5 and the third extension rod 413 and the hinge point of the third extension rod 413 and the seat frame support 2 is 22mm-26mm, and the distance between the two hinge points at two ends of the third extension rod 413 is 18cm-22cm. In this embodiment, the movement of the first annular four-bar linkage drives the movement of the linkage rod 5, and the movement of the linkage rod 5 rotates the third extension rod 413 relative to the seat frame bracket 5, so as to switch the pedal telescopic mechanism 4 between the extended or retracted positions. Specifically, the distance between the hinge point of the linkage rod 5 and the third extension rod 413 and the hinge point of the third extension rod 413 and the seat frame support 2 is 22mm-26mm, the distance between the two hinge points at two ends of the third extension rod 413 is 18cm-22cm, and the setting determines the minimum ground clearance of the seat iron frame.

Optionally, the third link 313 is provided with a first limit protrusion 3131, the first limit protrusion 3131 is located between the second link 312 and the fourth link 314, the first link 311 is provided with a second limit protrusion 3111, and the second limit protrusion 3111 is located at a side of the fourth link 314 away from the second link 312; the first limit protrusion 3131 is alternatively abutted against the fourth link 314 with the second limit protrusion 3111. In this embodiment, when the reclining iron stand is in the sitting mode or the TV mode, the second limiting protrusion 3111 abuts against the fourth link 314, so as to ensure stability of the backrest mechanism. When the sitting iron frame is in the lying mode, the first limiting protrusion 3131 is abutted with the fourth connecting rod 314, so that stability of the backrest mechanism is guaranteed.

The seat iron frame comprises three modes, namely a sitting posture mode, a TV mode and a lying posture mode, wherein in the sitting posture mode, the pedal telescopic mechanism 4 is in a retracted state, and an included angle between the backrest mechanism 3 and the seat frame bracket 2 is between 90 degrees and 135 degrees; when the seat iron frame is switched from the sitting posture mode to the TV mode, the driver drives the first stretching rod 411 to rotate around the seat frame bracket 2, and the auxiliary pedal 431 and the main pedal 42 are in stretching states; when the seat iron frame is switched from the TV mode to the lying mode, the driver continues to drive the first extension rod 411, at this time, the first extension rod 411 does not swing relative to the seat frame support 2, but drives the seat frame support 2 to move relative to the suspension mechanism 1 along a preset direction, at this time, the included angle between the backrest mechanism 3 and the seat frame support 2 changes accordingly, and the seat iron frame is further switched to the lying mode.

Example two

As shown in fig. 7, this embodiment is substantially the same as the first embodiment, and the only difference is that the second link 312 is bent twice, and the arrangement depends on the stress condition of the second link 312 when the driving rod drives the second link 312.

It is to be understood that the above examples of the present utility model are provided for clarity of illustration only and are not limiting of the embodiments of the present utility model. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the utility model are desired to be protected by the following claims.

Claims (13)

1. Backrest mechanism for seat iron frame, seat iron frame includes suspension mechanism (1) and with its articulated seat frame support (2), its characterized in that includes:

The four-bar linkage (31) and a driving piece (32), wherein the four-bar linkage (31) comprises a first connecting bar (311), a second connecting bar (312), a third connecting bar (313) and a fourth connecting bar (314) which are sequentially hinged and are arranged in a surrounding mode, the driving piece (32) is arranged on the hanging mechanism (1) and is connected with the four-bar linkage (31), and the seat frame support (2) can move relative to the hanging mechanism (1) along a preset direction so that the driving piece (32) can drive the four-bar linkage (31) to change shape;

in the process of changing the shape of the four-bar linkage (31), the moving distance of the hinge point of the third connecting bar (313) and the fourth connecting bar (314) is 60mm-100mm.

2. The backrest mechanism according to claim 1, characterized in that the first link (311) is fixedly connected with the seat frame bracket (2), and the driving member drives the second link (312) to rotate around a hinge point of the second link (312) and the first link (311).

3. The backrest mechanism according to claim 2, characterized in that the second link (312) is hinged to one end of the first link (311) and one end of the third link (313), respectively; the fourth connecting rod (314) is positioned on one side of the second connecting rod (312) and is hinged with one end of the first connecting rod (311) away from the second connecting rod (312) and one end of the third connecting rod (313) away from the second connecting rod (312) respectively.

4. A backrest mechanism according to claim 3, characterized in that the driving member (32) is a driving rod, one end of which is hinged to the suspension mechanism (1), one end of the second link (312) is hinged to the third link (313), the other end is hinged to the other end of the driving rod, and the middle part of the second link (312) is hinged to the first link (311).

5. The backrest mechanism according to any one of claims 1-4, characterized in that the third link (313) is provided with a first limit projection (3131), the first limit projection (3131) being located between the second link (312) and the fourth link (314), the first link (311) being provided with a second limit projection (3111), the second limit projection (3111) being located on a side of the fourth link (314) remote from the second link (312);

the first limit protrusion (3131) is alternatively abutted against the fourth connecting rod (314) with the second limit protrusion (3111).

6. Backrest mechanism according to claim 1, characterized in that the hinge point of the third link (313) and the fourth link (314) moves a distance of 70-95 mm during the change of shape of the four-bar linkage (31).

7. The backrest mechanism according to claim 1, characterized in that the hinge point of the third link (313) and the fourth link (314) moves a distance of 80-85 mm during the change of shape of the four-bar linkage (31).

8. Seat iron comprising a backrest mechanism (3) according to any one of claims 1 to 7, characterized in that it further comprises:

A suspension mechanism (1);

a seat frame bracket (2); is hinged with the suspension mechanism (1);

The seat frame support (2) can move relative to the suspension mechanism (1) along the preset direction, so that the driving piece (32) can drive the four-bar linkage (31) to change shape.

9. The seat iron frame according to claim 8, further comprising a pedal telescopic mechanism (4), wherein the pedal telescopic mechanism (4) is fixedly arranged on the seat frame support (2) and comprises an extension rod group (41), a main pedal (42) and an auxiliary pedal assembly (43), and the extension rod group (41) drives the main pedal (42) and the auxiliary pedal assembly (43) to extend or retract relative to the seat frame support (2).

10. The seat iron according to claim 9, wherein the set of extension bars (41) comprises a first extension bar (411), a second extension bar (412), a third extension bar (413) and a fourth extension bar (414), the first extension bar (411) being hinged to the second extension bar (412), the third extension bar (413) being hinged to the fourth extension bar (414), a middle portion of the first extension bar (411) being cross-hinged to a middle portion of the fourth extension bar (414), the first extension bar (411) and the third extension bar (413) being hinged to the seat frame support (2), respectively, the second extension bar (412) and the fourth extension bar (414) being hinged to the main (42), respectively.

11. The seat iron according to claim 10, characterized in that the secondary pedal assembly (43) comprises a secondary pedal (431) and a secondary connecting rod (432), both ends of the secondary connecting rod (432) are respectively hinged with the secondary pedal (431) and the primary pedal (42), and the middle part of the second extension rod (412) is hinged with the primary pedal (42); the end of the second extension rod (412) far away from the first extension rod (411) is hinged with the auxiliary pedal (431).

12. The seat iron according to claim 10, characterized in that the suspension mechanism (1) comprises a first rod (11), a second rod (12) and a third rod (13), wherein the first rod (11), the second rod (12), the third rod (13) and the seat frame support (2) are hinged end to end in sequence and are enclosed into a first annular four-bar structure;

The suspension mechanism (1) further comprises a fourth rod (14), a fifth rod (15), a sixth rod (16) and a seventh rod (17), wherein the middle part of the fourth rod (14) is hinged with one end of the fifth rod (15), the other end of the fifth rod (15) is hinged with one end of the sixth rod (16), the other end of the sixth rod (16) is hinged with the middle part of the seventh rod (17), one end of the seventh rod (17) is hinged with one end of the fourth rod (14), and the fourth rod (14), the fifth rod (15), the sixth rod (16) and the seventh rod (17) are enclosed to form a second annular four-bar structure;

The suspension mechanism (1) further comprises a first connecting rod (18) and a second connecting rod (19), the first connecting rod (18) comprises a first connecting strut (181) and a second connecting strut (182), one end of the first connecting strut (181) is hinged to the other end of the fourth rod (14), the other end of the first connecting strut (181) is hinged to the middle of the second rod (12), one end of the second connecting strut (182) is hinged to the middle of the fourth rod (14), the second rod (12) is hinged to the hinged end of the first rod (11) and the other end of the second connecting strut (182), one end of the second connecting rod (19) is hinged to the middle of the sixth rod (16), and the other end of the second connecting rod (19) is hinged to the second rod (12).

13. The seat iron frame according to claim 12, further comprising a linkage rod (5), wherein one end of the linkage rod (5) is hinged with the third extension rod (413), the other end of the linkage rod (5) is hinged with the third rod (13), the distance between the hinge point of the linkage rod (5) and the third extension rod (413) and the hinge point between the third extension rod (413) and the seat frame support (2) is 22mm-26mm, and the distance between the two hinge points at two ends of the third extension rod (413) is 18cm-22cm.