CN212754935U - Seat and backrest angle adjusting device thereof - Google Patents

Abstract

A chair and a backrest angle adjusting device thereof are provided, wherein the chair comprises a base frame, a backrest and a backrest angle adjusting device. The backrest angle adjusting device comprises a support frame, a first pivot assembly and a second pivot assembly. The support frame comprises a lower frame body and an upper frame body. The first pivot group is arranged between the base frame and the lower frame body and defines a first axis, and the support frame can rotate around the first axis relative to the base frame. The second pivot assembly is arranged between the backrest and the upper frame body and defines a second axis, the backrest can rotate between an initial angle position and a backward-leaning angle position relative to the upper frame body around the second axis, and the backrest can also rotate around the first axis through the support frame and the second pivot assembly. Therefore, the backrest can provide good support and comfort for the passengers.

Description

Seat and backrest angle adjusting device thereof

Technical Field

The utility model relates to a seat and lean against angular adjustment device thereof especially relate to a lean against can around the rotatory seat of two axes and lean against angular adjustment device thereof.

Background

A backrest angle adjusting device of the conventional chair is usually disposed between a rear portion of a base frame and a bottom portion of a backrest, thereby enabling the backrest to be rotated to adjust a reclining angle. Since the backrest can only rotate around a single axis by the backrest angle adjusting device, when a back of a rider leans backwards and applies force to push the backrest to rotate, a waist at the bottom end of the back is easy to separate from the backrest due to forward bulging, so that the backrest cannot completely fit to the waist and even the back of the rider, and the support and comfort provided by the backrest are poor.

Disclosure of Invention

One of the objects of the present invention is to provide a seat that can overcome at least one of the disadvantages of the background art.

The purpose of the utility model and the technical problem to be solved are realized by adopting the following technical proposal, according to the chair provided by the utility model, the chair comprises a base frame, a backrest and a backrest angle adjusting device, the backrest angle adjusting device comprises a support frame, a first pivot joint group and a second pivot joint group, the support frame comprises a lower frame body and an upper frame body, the first pivot assembly is arranged between the base frame and the lower frame body and defines a first axis, the support frame can rotate around the first axis relative to the base frame, the second pivot group is arranged between the backrest and the upper frame body and defines a second axis which is positioned above the first axis and is parallel to the first axis, the backrest can rotate around the second axis relative to the upper frame body between an initial angle position and a backward-leaning angle position, and the backrest can also rotate around the first axis through the support frame and the second pivot assembly.

The utility model discloses a seat, go up the support body and contain an at least support arm, the support arm has two looks spaced preceding pin joint boards, lean against and contain at least one and be located back pin joint board between the preceding pin joint board, second pin joint group includes that at least one defines out the pivot of second axis, the pivot pin joint preceding pin joint board with back pin joint board.

The utility model discloses a seat, it contains down the backstop to go up the support body, and is located the last backstop of backstop top down, the backstop is used for the stop down lean against in order to be spacing with it initial angular position, it is used for the stop to go up the backstop lean against in order to be spacing with it backward angle position.

The utility model discloses a seat, back angle adjusting device still contain set up in go up the support body with spring between the back, the spring is used for right back court initial angular position direction bias voltage.

The utility model discloses a seat, it contains two support arms to go up the support body, the back contains two back pin joint boards, second pin joint group includes that two define jointly the pivot of second axis, each the pivot pin joint corresponds the preceding pin joint board of support arm with correspond back pin joint board.

The utility model discloses a seat, each the support arm has down the backstop, and is located the last backstop of backstop top down, the backstop is used for the stop to correspond down back pin joint board bottom is in order to incite somebody to action it is spacing to lean back to initial angle position, it is used for the stop to correspond to go up the backstop back pin joint board top in order to incite somebody to action lean back to action spacing angle position is faced back to back.

The utility model discloses a seat, angle adjusting device leans against still contains two springs, each the spring set up in corresponding the support arm with correspond between the back pin joint board, be used for to corresponding back pin joint board is towards corresponding stop piece direction bias down.

The utility model discloses a seat, the support arm by lower carriage top extends up and towards the direction slope of keeping away from each other.

The utility model discloses a seat, lean against still to contain back of the body frame, and the screen cloth, back of the body frame is for sealing continuous structure and defining out the through-hole, the protruding locating of back pin joint board back of the body frame rear end and control looks interval, the screen cloth set up in back of the body frame front end just shield in the through-hole front end.

Another object of the present invention is to provide a backrest angle adjusting device for a seat that can overcome at least one of the disadvantages of the background art.

The utility model discloses an aim at and solve the background technical problem and adopt following technical scheme to realize, the foundation the utility model provides a chair lean against angular adjustment device is suitable for the setting between bed frame and backrest.

The backrest angle adjusting device comprises a support frame, a first pivot assembly and a second pivot assembly, the support frame comprises a lower frame body and an upper frame body, the first pivot assembly is arranged between the base frame and the lower frame body and defines a first axis, the support frame can rotate relative to the base frame around the first axis, the second pivot assembly is arranged between the backrest and the upper frame body and defines a second axis which is located above the first axis and parallel to the first axis, and the backrest can rotate between an initial angle position and a backward-leaning angle position relative to the upper frame body around the second axis.

The utility model discloses a chair lean against angle adjusting device, it contains an at least support arm to go up the support body, the support arm has two looks spaced preceding pin joint boards, lean against contain at least one be located back pin joint board between the preceding pin joint board, second pin joint group includes that at least one defines out the pivot of second axis, the pivot pin joint preceding pin joint board with back pin joint board.

The utility model discloses a chair lean against angular adjustment device, it contains down the backstop to go up the support body, and is located the last backstop of backstop top down, the backstop is used for the stop down lean against in order to be spacing with it initial angle position, it is used for the stop to go up the backstop lean against in order to be spacing with it backward angle position.

The utility model discloses a back angle adjusting device of seat still contain set up in go up the support body with lean against the spring between, the spring is used for right lean against the court initial angle position direction bias voltage.

The utility model discloses a chair lean against angular adjustment device, it contains two support arms to go up the support body, lean against and contain two back pin joint boards, second pin joint group includes that two define jointly the pivot of second axis, each the pivot pin joint corresponds the preceding pin joint board of support arm with correspond back pin joint board.

The utility model discloses a chair lean against angular adjustment device, each the support arm has down the stopper, and is located the last stopper of stopper top down, the stopper is used for the stopper to correspond down back pin joint board bottom is in order to incite somebody to action it is spacing to lean against initial angle position, it is used for the stopper to correspond to go up the stopper back pin joint board top is in order to incite somebody to action lean against spacingly back against backward angle position.

The utility model discloses a chair lean against angular adjustment device still contains two springs, each the spring set up in corresponding the support arm with correspond between the back pin joint board, be used for to corresponding back pin joint board is towards corresponding stop piece direction bias down.

The utility model discloses a backrest angle adjusting device of seat, the support arm by lower frame body top extends up and towards the direction slope of keeping away from each other.

The beneficial effects of the utility model reside in that: the backrest can rotate around the second axis relative to the upper frame body of the support frame between the initial angle position and the backward-leaning angle position, so that when the back of a rider pushes the backrest by applying force to cause the waist to bulge forwards, the backrest can still keep a state of completely and completely attaching to the back and the waist, and good support and comfort of the back and the waist are provided.

Drawings

FIG. 1 is a perspective view of an embodiment of a chair according to the present invention;

FIG. 2 is a fragmentary exploded perspective view of the embodiment, illustrating the assembly relationship between the base frame, the backrest, and the backrest angle adjustment device;

FIG. 3 is a fragmentary exploded perspective view of the embodiment, illustrating the assembled relationship between the backrest and the backrest angle adjustment device;

FIG. 4 is a fragmentary cross-sectional view of the embodiment, illustrating the backrest and support bracket each in an initial angular position;

FIG. 5 is a fragmentary cross-sectional view of the embodiment illustrating a first pivot group disposed between the base frame and the lower frame of the support frame;

FIG. 6 is a fragmentary cross-sectional view of the embodiment;

FIG. 7 is a fragmentary cross-sectional view of the embodiment illustrating a second pivot group disposed between the backrest and the upper frame of the support frame;

FIG. 8 is a fragmentary cross-sectional view of the embodiment illustrating details of the locking mechanism;

FIG. 9 is a fragmentary cross-sectional view of the embodiment;

FIG. 10 is a fragmentary cross-sectional view of the embodiment, illustrating the backrest in a rear elevational position;

fig. 11 is a fragmentary cross-sectional view of the embodiment, illustrating the backrest in the reclined angular position and the support bracket in a reclined angular position.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings and examples.

Before the present invention is described in detail, it should be noted that in the following description, like elements are represented by like reference numerals.

Referring to fig. 1, an embodiment of a chair 100 of the present invention includes a cushion 1, a base frame 2, a backrest 3, and a backrest angle adjusting device 4.

Referring to fig. 1, 2 and 3, the base frame 2 is disposed at the bottom of the seat cushion 1 and includes a top plate 21, two side plates 22 extending downward from left and right sides of the top plate 21, and a frame plate 23 disposed inside the corresponding side plates 22. The backrest 3 comprises a back frame 31, a mesh 32, and two rear pivoting plates 33. The back frame 31 is a frame-shaped closed continuous structure and defines a through hole 311. The mesh 32 is a mesh with good elasticity and air permeability, and is disposed at the front end of the back frame 31 and covers the front end of the through hole 311, and the mesh 32 is used for a back and a waist of a rider (not shown) to lean against. Borrow by the back of the body frame 31 is the frame shape and the screen cloth 32 set up in back of the body frame 31 front end and shield in the mode of through-hole 311 front end makes the screen cloth 32 can pass through-hole 311 reaches good ventilative radiating effect, in order to promote the confession the back and the comfort when the waist pastes. The rear pivoting plate 33 is protruded at the rear end of the back frame 31 and spaced left and right.

Referring to fig. 3, 4 and 5, the backrest angle adjusting device 4 includes a supporting frame 41, a first pivot set 42, a second pivot set 43, two springs 44, two springs 45 and a locking mechanism 46. The supporting frame 41 is Y-shaped and includes a lower frame 410 and an upper frame 411. The lower frame 410 is formed in an arc shape protruding backward and has two side plates 412 adjacent to the bottom and spaced from each other at left and right, and a shaft 413 penetrating the side plates 412 and adjacent to the bottom thereof. The side plates 412 are respectively located outside the side plates 22. The upper frame body 411 has two arms 414, and the arms 414 extend from the top of the lower frame body 410 upwards and obliquely away from each other, so that each arm 414 is inclined.

Referring to fig. 2, 4 and 6, each of the arms 414 has a front end face 415, two front pivoting plates 416, a lower stop 417 and an upper stop 418. The front pivot plate 416 is protruded from the front end surface 415 and spaced apart from each other in the left-right direction, the front end surface 415 and the front pivot plate 416 together define a receiving groove 419, and the receiving groove 419 is used for receiving the corresponding rear pivot plate 33. The lower stopping block 417 is protruded from the front end surface 415 and located below the accommodating groove 419 for stopping the bottom end of the corresponding rear pivoting plate 33. The upper stop block 418 is protruded from the front end surface 415 and located above the lower stop block 417 and the receiving slot 419 for stopping the top end of the corresponding rear pivot plate 33.

Referring to fig. 4 and 5, the first pivot assembly 42 includes a pivot 421, the pivot 421 penetrates through and is pivotally connected to the side plate 22 and the side plate 412, and the pivot 421 defines a first axis a 1. Thereby, the support bracket 41 is enabled to rotate relative to the base frame 2 about the first axis a 1. Each of the springs 44 is a torsion spring sleeved on the pivot 421, and two opposite ends of each of the springs 44 respectively abut against the bottom end of the top plate 21 and the top end of the shaft 413.

Referring to fig. 2, 4, 6 and 7, the second pivot set 43 includes two pivots 431 and two retaining rings 432. Each pivot 431 is inserted through and pivoted to the front pivoting plate 416 of the corresponding arm 414 and the corresponding rear pivoting plate 33. Each of the retaining rings 432 is fastened to the corresponding pivot 431 and abuts against the outer side of the corresponding front pivoting plate 416 to prevent the pivot 431 from separating from the front pivoting plate 416 and the rear pivoting plate 33. The pivots 431 together define a second axis a2, and the second axis a2 is located above the first axis a1 and parallel to the first axis a 1. Thereby, the backrest 3 can rotate around the second axis a2 between an initial angular position (as shown in fig. 4) and a reclining angular position (as shown in fig. 10) relative to the upper frame 411. In addition, the backrest 3 can also rotate around the first axis a1 through the supporting frame 41 and the second pivot group 43. Each of the springs 45 is a torsion spring sleeved on the corresponding pivot 431, and two opposite ends of each of the springs 45 respectively abut against the corresponding front pivot plate 416 and the corresponding rear pivot plate 33.

Referring to fig. 5, 8 and 9, the locking mechanism 46 includes a washer 461, a nut 462, a washer 463, a resilient pad 464, a movable rod 465, a plurality of friction plates 466, a plurality of friction pads 467, an operating rod 468 and a pin 469. The spacer 461 is configured to abut against an outer side of an inner plate 231 of the frame plate 23. The nut 462 abuts against the outside of the washer 461. The washer 463 abuts on the inner side of the inner plate portion 231. The elastic cushion 464 penetrates through the corresponding side plate 22 and is spaced apart from the gasket 463. The movable rod 465 penetrates through the elastic cushion block 464, the washer 463, the inner plate 231 and the washer 461 and is screwed with the nut 462. Each friction plate 466 is elongated and has an axial hole 470 pivotally connected to the shaft 413, and an elongated hole 471 through which the movable rod 465 passes. The friction pads 467 are sleeved on the movable rod 465, one of the friction pads 467 is located between the washer 463 and the corresponding friction plate 466, the other of the friction pads 467 is located between the elastic cushion block 464 and the corresponding friction plate 466, and the rest of the friction pads 467 are located between two adjacent friction plates 466. A pivotal housing 472 of the operating lever 468 is pivotally connected to the movable lever 465 through the latch 469, and is configured to drive the movable lever 465 to move laterally for unlocking and locking operations.

To perform the unlocking operation, the operating lever 468 is pushed down to rotate in the first rotational direction S1. The operating rod 468 pushes the movable rod 465 to move transversely along a first moving direction D1 through the pin 469 during rotation, and the movable rod 465 drives the friction plates 466 and the friction pads 467 to move through friction force during movement, so that each friction plate 466 is released from two adjacent friction pads 467 without being in tight contact with each other, so as to allow each friction plate 466 to move relative to the corresponding friction pad 467 and the movable rod 465. At this time, when the locking mechanism 46 is in an unlocked state, the supporting bracket 41 can rotate around the first axis a1 in a first rotating direction R1 (as shown in fig. 11) to adjust the angle, and the friction plate 466 is pushed by the shaft 413 to move upward relative to the movable bar 465 during the rotation of the supporting bracket 41.

When the supporting bracket 41 is adjusted to a desired angle, the operating lever 468 is pulled upward to rotate in a second rotating direction S2 opposite to the first rotating direction S1. The rotation of the operating lever 468 pulls the movable lever 465 through the latch 469 to move laterally in a second moving direction D2 opposite to the first moving direction D1. The movable rod 465 drives the nut 462 and the washer 461 to move transversely in the second moving direction D2 during the moving process, and at the same time, the pivot housing 472 presses the elastic pad 464 in the first moving direction D1, so that the elastic pad 464 presses the friction plates 466 and the friction washers 467 to move transversely in the first moving direction D1, and each friction plate 466 and two adjacent friction washers 467 are pressed together. Due to the friction force between each friction plate 466 and the corresponding friction washer 467, each friction plate 466 cannot move relative to the corresponding friction washer 467 and the movable rod 465. At this time, the locking mechanism 46 is in a locked state to lock the support bracket 41 at a desired angular position.

Referring to fig. 4, 6 and 9, when the locking mechanism 46 is in the unlocked state, the shaft 413 is biased by the springs 44 in a direction away from the top plate 21, so that the top end of the elongated hole 471 of each friction plate 466 is constantly abutted against the movable rod 465 to limit the supporting frame 41 at an initial angular position as shown in fig. 4. The springs 45 bias the corresponding rear pivoting plate 33 toward the corresponding lower stopping block 417, so that the bottom end of the rear pivoting plate 33 is constantly abutted against the lower stopping block 417. Thereby limiting the backrest 3 to the initial angular position as shown in fig. 6.

Referring to fig. 10 and 11, when the occupant wants to adjust the reclining angle of the backrest 3, the operating lever 468 is operated to first switch the locking mechanism 46 to the unlocked state. The occupant then leans back through the back and applies a force to push the backrest 3. Since the second pivot group 43 is disposed between the rear pivot plate 33 of the backrest 3 and the arm 414 of the upper frame 411, the backrest 3 rotates around the second axis a2 relative to the upper frame 411 from the initial angular position along the first rotation direction R1 when being pushed by a force. During the rotation of the backrest 3, the rear pivoting plates 33 respectively compress the springs 45 (as shown in fig. 6) to deform and accumulate the return elastic force, and at the same time, the backrest 3 respectively applies a force to the arms 414 through the pivot shafts 431 to urge the supporting frame 41 to rotate from the initial angular position in the first rotation direction R1 around the first axis a1 relative to the base frame 2. During the rotation of the supporting frame 41, the shaft 413 compresses the spring 44 to deform and store the return elastic force.

Since the backrest 3 can rotate around the second axis a2 relative to the upper frame 411 along the first rotation direction R1, when the back portion pushes the backrest 3 to cause the waist portion to bulge forward, the mesh 32 of the backrest 3 can still keep a state of completely adhering to the back portion and the waist portion, so as to provide good support and comfort for the back portion and the waist portion. In addition, the upper frame body 411 is obliquely protruded from the top of the lower frame body 410 via the supporting arm 414, and is respectively pivoted to the rear pivoting plate 33 of the backrest 3 via the second pivoting group 43, so that the backrest 3 can be uniformly pressed on the supporting arm 414 via the pivot 431 spaced from each other at left and right when being pushed by a force, and the uniformity of the force applied to the upper frame body 411 can be effectively improved. Furthermore, the lower frame 410 can combine the pressures output by the support arms 414 into a resultant force, so that the shaft 413 of the lower frame 410 can easily compress the spring 44 to deform the spring, thereby improving the smoothness of the support frame 41 rotating around the first axis a 1.

When the top end of each rear pivoting plate 33 of the backrest 3 abuts against and is stopped by the corresponding upper stop block 418, the backrest 3 cannot rotate relative to the upper frame 411 and is limited to the reclining angle position as shown in fig. 11. When the bottom end of the elongated hole 471 (shown in fig. 9) of each friction plate 466 abuts against and is blocked by the movable rod 465, the supporting frame 41 cannot rotate relative to the base frame 2 and is limited to a backward tilting angle position shown in fig. 11.

In this embodiment, the occupant can also adjust the reclining angle by only rotating the backrest 3 in the first rotating direction R1 about the second axis a2 as shown in fig. 10, instead of adjusting the reclining angle by rotating the support bracket 41 about the first axis a 1.

Referring to fig. 4 and 11, when the occupant wants to adjust the forward tilt angle of the backrest 3, the back is tilted forward. The backrest 3 is rotated around the second axis a2 in a second rotation direction R2 opposite to the first rotation direction R1 by the return elastic force accumulated by the spring 45, and the support bracket 41 is rotated in the second rotation direction R2 by the return elastic force accumulated by the spring 44, so as to adjust the forward tilting angle of the backrest 3. When the back and waist of the rider move away from the mesh 32 of the backrest 3, the return elastic force accumulated by the springs 45 and 44 automatically returns the backrest 3 and the support frame 41 to the initial angular position, respectively.

It should be noted that, in other embodiments of the present embodiment, the number of the rear pivotal plate 33 of the backrest 3, the arm 414 of the upper frame 411, and the number of the pivots 431 of the second pivotal group 43 may be respectively designed to be one according to requirements, and the number is not limited to the number disclosed in the present embodiment.

To sum up the above, the seat 100 of the embodiment can rotate between the initial angular position and the reclining angular position about the second axis a2 for the upper frame 411 of the supporting frame 41 by the backrest 3, so that the backrest 3 can still be completely attached to the back and the waist when the back of the rider pushes the backrest 3 to cause the waist to bulge forward, thereby providing good support and comfort for the back and the waist, and indeed achieving the purpose of the present invention.

Claims (17)

1. A seat is provided; the method is characterized in that:

the seat comprises a base frame, a backrest and a backrest angle adjusting device, wherein the backrest angle adjusting device comprises a support frame, a first pivot assembly and a second pivot assembly, the support frame comprises a lower frame body and an upper frame body, the first pivot assembly is arranged between the base frame and the lower frame body and defines a first axis, the support frame can rotate relative to the base frame around the first axis, the second pivot assembly is arranged between the backrest and the upper frame body and defines a second axis which is located above the first axis and parallel to the first axis, the backrest can rotate relative to the upper frame body between an initial angle position and a backward-lying angle position, and the backrest can rotate around the first axis through the support frame and the second pivot assembly.

2. The seat according to claim 1, wherein: the upper frame body comprises at least one support arm, the support arm is provided with two spaced front pivoting plates, the backrest comprises at least one rear pivoting plate located between the front pivoting plates, the second pivoting group comprises at least one pivot defining the second axis, and the pivot is pivoted with the front pivoting plate and the rear pivoting plate.

3. The seat according to claim 1, wherein: the upper frame body comprises a lower stop block and an upper stop block positioned above the lower stop block, the lower stop block is used for stopping the backrest to limit the backrest at the initial angle position, and the upper stop block is used for stopping the backrest to limit the backrest at the backward-bending angle position.

4. The seat according to claim 1, wherein: the backrest angle adjusting device further comprises a spring arranged between the upper frame body and the backrest, and the spring is used for biasing the backrest towards the initial angle position direction.

5. The seat according to claim 2, wherein: the upper frame body comprises two support arms, the backrest comprises two rear pivoting plates, the second pivoting group comprises two pivots which define the second axis together, and each pivot is pivoted with the corresponding front pivoting plate of the support arm and the corresponding rear pivoting plate.

6. The seat according to claim 5, wherein: each support arm is provided with a lower stop block and an upper stop block positioned above the lower stop block, the lower stop block is used for stopping the bottom end of the corresponding rear pivoting plate so as to limit the backrest at the initial angle position, and the upper stop block is used for stopping the top end of the corresponding rear pivoting plate so as to limit the backrest at the backward-leaning angle position.

7. The seat according to claim 6, wherein: the backrest angle adjusting device further comprises two springs, and each spring is arranged between the corresponding support arm and the corresponding rear pivoting plate and used for biasing the corresponding rear pivoting plate towards the direction of the corresponding lower stop block.

8. The seat according to claim 5, wherein: the support arms extend upwards from the top of the lower frame body and obliquely towards the directions away from each other.

9. The seat according to claim 5, wherein: the backrest further comprises a back frame and a mesh, the back frame is of a closed continuous structure and defines through holes, the rear pin joint plate is convexly arranged at the rear end of the back frame and is spaced from the left end to the right end, and the mesh is arranged at the front end of the back frame and is shielded at the front end of the through holes.

10. A backrest angle adjusting device of a chair is suitable for being arranged between a base frame and a backrest; the method is characterized in that:

the backrest angle adjusting device comprises a support frame, a first pivot assembly and a second pivot assembly, the support frame comprises a lower frame body and an upper frame body, the first pivot assembly is arranged between the base frame and the lower frame body and defines a first axis, the support frame can rotate relative to the base frame around the first axis, the second pivot assembly is arranged between the backrest and the upper frame body and defines a second axis which is located above the first axis and parallel to the first axis, and the backrest can rotate between an initial angle position and a backward-leaning angle position relative to the upper frame body around the second axis.

11. The backrest angle adjusting apparatus of a seat according to claim 10, wherein: the upper frame body comprises at least one support arm, the support arm is provided with two spaced front pivoting plates, the backrest comprises at least one rear pivoting plate located between the front pivoting plates, the second pivoting group comprises at least one pivot defining the second axis, and the pivot is pivoted with the front pivoting plate and the rear pivoting plate.

12. The backrest angle adjusting apparatus of a seat according to claim 10, wherein: the upper frame body comprises a lower stop block and an upper stop block positioned above the lower stop block, the lower stop block is used for stopping the backrest to limit the backrest at the initial angle position, and the upper stop block is used for stopping the backrest to limit the backrest at the backward-bending angle position.

13. The backrest angle adjusting apparatus of a seat according to claim 10, wherein: the spring is arranged between the upper frame body and the backrest and used for biasing the backrest towards the direction of the initial angle position.

14. The backrest angle adjusting apparatus of a seat according to claim 11, wherein: the upper frame body comprises two support arms, the backrest comprises two rear pivoting plates, the second pivoting group comprises two pivots which define the second axis together, and each pivot is pivoted with the corresponding front pivoting plate of the support arm and the corresponding rear pivoting plate.

15. The backrest angle adjusting apparatus of a seat according to claim 14, wherein: each support arm is provided with a lower stop block and an upper stop block positioned above the lower stop block, the lower stop block is used for stopping the bottom end of the corresponding rear pivoting plate so as to limit the backrest at the initial angle position, and the upper stop block is used for stopping the top end of the corresponding rear pivoting plate so as to limit the backrest at the backward-leaning angle position.

16. The backrest angle adjusting apparatus of a seat according to claim 15, wherein: the spring is arranged between the corresponding support arm and the corresponding rear pivoting plate and used for biasing the corresponding rear pivoting plate towards the direction of the corresponding lower stop block.

17. The backrest angle adjusting apparatus of a seat according to claim 14, wherein: the support arms extend upwards from the top of the lower frame body and obliquely towards the directions away from each other.

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