Chassis of swivel chair

Abstract

A gravity self-adapted chassis of chair has the first plug pin, second plug pin, third plug pin, forth plug pin, tilting plate, first connecting rod, and the second connecting rod of the chassis form into a four-point connecting rod mechanism so as to form the conduction of the force, the backrest is fixedly connected with the tilting plate to offer the driving force of the four-point connecting rod mechanism, the gravity applied onto the seat by the users forms into the reset force applied onto the four-point connecting rod mechanism through the third plug pin hinged with the bracket, and the driving force and the reset force of the four-point connecting rod mechanism form into the confrontation relationship.

Claims

1. A chassis of a swivel chair comprising: a base (1) connected with an air rod, a bracket (2) used for fixing a seat and a tilting plate (3) connected with the backrest (2); wherein the bracket (2) is arranged within the base (1), the tilting plate (3) is arranged within the bracket (2); a middle of the tilting plate (3) is provided with a first pin shaft (11) as a rotating shaft thereof, the first pin shaft (11) penetrates through the bracket (2) and is connected with the base (1); two first connecting rods (13) and two second connecting rods (14) are symmetrically arranged at two sides of a front part of the tilting plate (3) respectively, one end of the first connecting rod is hinged with a front end of the tilting plate through a fourth pin shaft (16), the other end of the first connecting rod (13) is hinged with one end of the second rod (14) through a third pin shaft (15), the third pin shaft (15) is connected with the bracket (2), the other end of the second connecting rod (14) is provided with a second pin shaft (12), the second pin shaft (12) is connected with the base (1) after penetrating though the bracket (2); two track grooves (17) which are matched with the first pin shaft (11) and used for guiding the motion trail of the bracket (2) are symmetrically arranged at two sides of the bracket (2) respectively, the first pin shaft (11) is moveably arranged within the track grooves (17); and the chassis further comprises an elastic reset device which leads the bracket (2) to be reset after the bracket is tilted by the tilting plate to move.

2. The chassis of the swivel chair according to claim 1, wherein two hollow grooves (18) are symmetrically arranged at two sides of the bracket (2), the second pin shaft (12) penetrates the hollow grooves (18) freely and is movable therein.

3. The chassis of the swivel chair according to claim 2, wherein the second pin shaft (12) is an integrated long shaft, and two ends of the second pin shaft (12) are connected with the base (1) after respectively penetrating through the second connecting rod (14) and the hollow grooves (18); or the second pin shaft (12) is two independent short shafts, one end of each short shaft is connected with the base (1) after penetrating through the second connecting rod (14) and the hollow grooves (18).

4. The chassis of the swivel chair according to claim 2, wherein the track grooves (17) and the hollow grooves (18) are all arranged in a tilting position.

5. The chassis of the swivel chair according to claim 1, wherein parts of two sides of the bracket (2), which interferes with the second pin shaft (12), are cut, so that the second pin shaft (12) does not contact the bracket (2).

6. The chassis of the swivel chair according to claim 1, wherein the first pin shaft (11) is an integrated long shaft, and two ends of the first pin shaft are connected with the base (1) after respectively penetrating through the tilting plate (3) and the track groove (17).

7. The chassis of the swivel chair according to claim 1, wherein a connection between the first pin shaft (11) and the base (1) is made by two first pin holes (9) that are symmetrically arranged at two sides of the back end of the base (1) and the first pin shaft (11) that is inserted into the first pin holes (9); a connection between the second pin shaft (12) and the base (1) is made by two second pin holes (10) that are symmetrically arranged at two ends of the front end of the base (1) and the second pin shaft (12) that is inserted into the second pin holes (10); and a connection between the third pin shaft and the base is made by the third pin shaft (15) that is inserted into the bracket (2) and is used for driving the bracket to synchronously move.

8. The chassis of the swivel chair according to claim 1, wherein the base (1) comprises a base plate (4) connected with the air rod, two support plates (5) that are respectively arranged at the left side and the right side of the base plate (4) along a vertical direction, the support plates (5) being fixedly connected with the base plate (4), and the first pin shaft (11) and the second pin shaft (12) connected with the support plates (5) of the base (1); the bracket (2) comprises two basal plates (6) which are in parallel with each other and arranged along a vertical direction, the upper ends of the basal plates (6) are bent to form a supporting plate (7) used for being connected with a seat, a connecting plate (8) is fixedly connected between the two basal plates (6), and the tilting plate (3) is arranged between the two basal plates (6).

9. The chassis of the swivel chair according to claim 1, wherein the first connecting rod (13) is arranged in a tilting position toward the tilting plate (3), the second connecting rod (14) is arranged in a tilting position oriented away from the tilting plate (3), and when the bracket (2) moves, an inclined angle between the second connecting rod (14) and a plumb line is less than or equal to 90 degrees.

10. The chassis of the swivel chair according to claim 1, wherein the chassis is further provided with a backrest tilting plate locking mechanism, wherein the backrest tilting plate locking mechanism comprises a row of lock holes (21) symmetrically arranged on the two sides of the tilting plate (3) as well as two torsion springs (23), two plug pins (23) and two plug pin bases (24), which are symmetrically arranged at the two sides within the base (1), the plug pin bases (24) are fixedly arranged on the base (1), the plug pins (23) are inserted through the plug pin bases (24) to slide relative thereto and are matched with the lock holes, first spring arms (25) of the torsion springs (23) are connected with the plug pins (23), and second spring arms (26) of the torsion springs (23) are connected with a drive device used for driving the torsion springs (23) to rotate.

11. The chassis of the swivel chair according to claim 10, wherein the drive device comprises a crank (27), a positioning base (28) and a stirring rod (29), wherein the positioning base (28) is fixedly connected with the base (1), the positioning base (28) is arc-shaped and is hollow in an inner part, an upper end of the positioning base (28) is provided with an arc lug boss (30) which extends downwards, the lug boss (30) is configured to divide the upper end in the positioning base (28) into two positioning grooves (31), the positioning base (28) is internally provided with a fixture block (35), an upper end of the fixture block (35) is clamped within the positioning grooves (31), two ends of the crank (27) are connected with the second spring arms of the two torsion springs (23), the crank (27) is connected with the fixture block (35) through a rocker (32), one end of the stirring rod (29) is fixedly connected with the fixture block (35) after penetrating through the base (1), and the other end of the stirring rod (29) extends outside of the base (1); the stirring rod (29) is movable forward and backward so that the fixture block (35) moves from one positioning groove into the other positioning groove, and the fixture block (35) rotates to drive the crank (27) such that the two torsion springs (23) are driven to rotate and under the action of the elasticity of the rotated torsion springs (23), the first spring arms drive the plug pins (23) into the corresponding lock holes (21) or out of the lock holes (21) to realize the lock and the unlock of the plug pins (23) respectively.

12. The chassis of the swivel chair according to claim 11, wherein the drive device further comprises two stand columns (33) for installing the torsion springs (23), the upper end of each stand column (33) is provided with a screw, the torsion springs (23) are arranged onto the screws, the lower end of each stand column (33) is fixedly connected with the base (1) through an arc bridge, a shaft hole (40) is formed between each arc bridge and the bottom surface of the base (1), and the stirring rod (29) penetrates through one of the arc bridges to be connected with the fixture block (35).

13. The chassis of the swivel chair according to claim 1, wherein the bracket (2) is connected with the elastic reset device, the elastic reset device is a spring (19), one end of the spring (19) is connected with the bracket (2), and the other end of the spring is connected with the base (1).

14. The chassis of the swivel chair according to claim 1, wherein the fourth pin shaft (16) is an integrated long shaft, and two ends of the fourth pin shaft (16) are respectively connected with one end of the first connecting rod (13) and the front end of the tilting plate (3).

15. The chassis of the swivel chair according to claim 14, wherein the chassis is further provided with a backrest tilting plate locking mechanism, wherein the backrest tilting plate locking mechanism comprises a lock plate (56), a torsion spring (22), a plug pin (23) and a plug pin base (24), a row of lock holes (21) are arranged on the lock plate (56), the lock plate (56) is fixedly connected with the fourth pin shaft (16) and moves synchronously with the fourth pin shaft (16) under the action of the tilting plate (3), the plug pin base (24) is arranged beside the lock plate (56) and is fixedly connected with the base (1), the plug pin (23) is inserted through the plug pin base (24) to slide relative thereto and is matched with the lock holes (21), a first spring arm (25) of the torsion spring (22) is connected with the plug pin (23), and a second spring arm (26) of the torsion spring (22) is connected with a drive device used for driving the torsion spring (22) to rotate.

16. The chassis of the swivel chair according to claim 15, wherein the drive device comprises a support base (59), a stirring rod (29) and a positioning ring (60) which is deformable, wherein the support base (59) is fixedly arranged on the plug pin base (24), the positioning ring (60) is fixedly arranged on the support base (59), the torsion spring (22) is mounted on a screw (39), the screw (39) is fixedly arranged on the support base (59), the positioning ring (60) is internally provided with a kidney-shaped hole (61), an arc lug boss is arranged in the middle of the kidney-shaped hole (61), the poisoning ring (60) is internally divided into two clamp grooves (62) due to the configuration of the lug boss (30), one end of the stirring rod (29) extends into the positioning ring (60) after penetrating through the base (1), and the other end of the stirring rod (29) extends outside of the base (1); a second spring arm (26) of the torsion spring (22) is connected with the end of the stirring rod (29), which extends into the positioning ring (60), and the stirring rod (29) is movable, so that the one end of the stirring rod moves into one of the clamp grooves (62), and the torsion spring (22) is driven to rotate; and under the elasticity action of the torsion spring (22) the first spring arm (25) moves the plug pin (23) to be inserted into the corresponding lock holes (21) or withdrawn out of the lock holes (21), so that the plug pin (23) can be locked and unlocked respectively.

17. The chassis of the swivel chair according to claim 15, wherein the plane where the lock plate (56) is arranged is perpendicular to the axis of the fourth pin shaft (16), and an upper end face (63a) and a lower end face (63b) of the lock plate are concaved to form grooves (64) which are matched with the plug pin (23), such that when the plug pin (23) is clamped within one of the grooves (64) of the upper end face (63a) and the lower end face (64a), the tilting plate can be locked at an initial angle and a maximum angle respectively.

18. The chassis of the swivel chair according to claim 15, wherein a plastic sleeve (55) is mounted onto the fourth pin shaft (16), the plastic sleeve (55) has a gap (58), and an extension section (57) of the lock plate (56) is properly clamped within the gap (58).

19. The chassis of the swivel chair according to claim 1, wherein the fourth pin shaft (16) is connected with the elastic reset device, the elastic reset device is a spring (19), one end of the spring (19) is connected with the fourth pin shaft (16), and the other end of the spring (19) hooks the base (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is the three-dimensional structure schematic diagram of the chassis of the present invention in embodiment 1;

(2) FIG. 2 is the three-dimensional structure schematic diagram of the other angle of the chassis of the present invention in embodiment 1;

(3) FIG. 3 is the schematic diagram where the tilting plate and the bracket are under the initial state in embodiment 1;

(4) FIG. 4 is the schematic diagram where the tilting plate and the bracket are under the tilting state in embodiment 1;

(5) FIG. 5 is the split structure schematic diagram of the bracket and the base in embodiment 1;

(6) FIG. 6 is the split structure schematic diagram of the other angle of the bracket and the base in embodiment 1;

(7) FIG. 7 is the structure schematic diagram of the backrest tilting plate locking mechanism in embodiment 1;

(8) FIG. 8 is the schematic diagram where the plug pin of the backrest tilting plate locking mechanism is unlocked in embodiment 1;

(9) FIG. 9 is the schematic diagram where the plug pin of the backrest tilting plate locking mechanism is locked at the initial angle in embodiment 1;

(10) FIG. 10 is the schematic diagram where the plug pin of the backrest tilting plate locking mechanism is locked at the maximum angle in embodiment 1;

(11) FIG. 11 is the structure schematic diagram of the other angle of the backrest tilting plate locking mechanism in embodiment 1;

(12) FIG. 12 is the match structure schematic diagram of the crank, the positioning base and the fixture block in the drive device under the status that the plug pin is unlocked in embodiment 1;

(13) FIG. 13 is the match structure schematic diagram of the crank, the positioning base and the fixture block in the drive device under the status that the plug pin is locked in embodiment 1;

(14) FIG. 14 is the three-dimensional structure schematic diagram of the chassis in embodiment 2;

(15) FIG. 15 is the split structure schematic diagram of the bracket and the base in embodiment 2;

(16) FIG. 16 is the schematic diagram where the users do not tilt when sitting on the swivel chair;

(17) FIG. 17 is the schematic diagram where the users backwards tilt when sitting on the swivel chair;

(18) FIG. 18 is the three-dimensional structure schematic diagram of the chassis in embodiment 3;

(19) FIG. 19 is the split structure schematic diagram of the chassis in embodiment 3;

(20) FIG. 20 is the structure schematic diagram of the chassis in embodiment 4;

(21) FIG. 21 is the structure schematic diagram of the chassis in embodiment 5;

(22) FIG. 22 is the structure schematic diagram of the chassis in embodiment 6;

(23) FIG. 23 is the local structure schematic diagram of the chassis in embodiment 7;

(24) FIG. 24 is the exploded view of FIG. 23;

(25) FIG. 25 is the schematic diagram where the plug pin of the backrest tilting plate locking mechanism is unlocked in embodiment 8;

(26) FIG. 26 is the enlarged drawing of the part A of FIG. 25;

(27) FIG. 27 is the schematic diagram of the plug pin of the backrest tilting plate locking mechanism when the tilting plate is locked at the initial angle in embodiment 8;

(28) FIG. 28 is the schematic diagram of the plug pin of the backrest tilting plate locking mechanism when the tilting plate is locked at the maximum angle in embodiment 8;

(29) FIG. 29 is the whole structure schematic diagram of the chassis when the tilting plate is under the initial angle in embodiment 8;

(30) FIG. 30 is the whole structure schematic diagram of the chassis when the tilting plate is under the maximum angle in embodiment 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(31) The specific embodiments of the present invention are as follows:

(32) Embodiment 1: firstly, the reference position of each part of the present invention is defined, when the chassis and the swivel chair are normally installed and used, the front of the swivel chair is the front end, the back of the swivel chair, inducing the position where the backrest is arranged, is the back end, the front end of the chassis is the region which is far away from the tilting plate, and the back end of the chassis is the region which is near to the tilting plate.

(33) A chassis of a swivel chair, as show in FIG. 1-FIG. 6, comprising a base 1 connected with an air rod, a bracket 2 for fixing the chair and a tilting plate 3 connected with the backrest, wherein the bracket 2 is arranged within the base 1, and the tilting plate 3 is arranged within the bracket 2; specifically, the base 1 comprises a base plate 4 connected with the air rod, two support plates 5 are respectively arranged at the left side and the right side of the base plate 4 along the vertical direction, the support plates 5 are fixedly connected with the base plate 4, and the base plate 4 plays a part in supporting the whole chassis, the seat and the backrest; the bracket 2 comprises two basal plates 6 which are in parallel with each other at intervals and arranged along the vertical direction, the basal plates 6 are adhered to the support plates 5, the upper ends of the basal plates 6 are bent to form a support plate 7 to be connected with the seat, connecting plates 8 are fixedly connected between the two basal plates 6, the connecting plates 8 are plural, the two basal plates 6 are fixedly connected with each other by the connecting plates 8, and the tilting plate 3 is arranged between the two basal plates 6.

(34) A first shaft hole 9 and a second shaft hole 10 are symmetrically arranged at the back end and the front end of the support plates 5 at two sides of the base 1, the middle of the tilting plate 3 is provided with a first pin shaft 11 in a penetrating way, the first pin shaft 11 is taken as the rotating fulcrum of the tilting plate 3, the first pin shaft 11 is an integrated long shaft, and two ends of the first pin shaft 11 are inserted into the first shaft hole 9 after respectively penetrating through the tilting plate 3 and the bracket 2 in sequence; a first connecting rod 13 and a second connecting rod 14 are symmetrically arranged at two sides at the front of the tilting plate 3, as shown in FIG. 2, the first connecting rod 13 is arranged in a tilting way towards the direction which is near to the tilting plate 3 from bottom to top, the second rod 14 is arranged in a tilting way towards the direction which departs from the tilting plate 3 from bottom to top, and when the bracket 2 moves, the inclined angle between the connecting rod 14 and the plumb line is always not more than 90 degrees.

(35) One end of the first connecting rod 13 is hinged with the front end of the tilting plate 3 through a fourth pin shaft 16, the other end of the first connecting rod 13 is hinged with one end of the second rod 14 through a third pin shaft 15, the third pin shaft 15 is inserted into the bracket 2, the other end of the second connecting rod 14 is provided with a second pin shaft 12 in a penetrating way, the second pin shaft 12 penetrates through the bracket 2 and is inserted into the second shaft hole 10, the second pin shaft 12 is an integrated long shaft, and two ends of the second pin shaft 12 are inserted into the second shaft hole 10 after respectively penetrating through the second connecting rod 14 and the bracket 2 in sequence; the tilting plate 3 drives the bracket 2 move through the connecting rods, so that the basal plates 6 arranged at two sides of the bracket 2 are respectively provided with a track groove 17 which is matched with the first pin shaft 11 to guide the motion track of the bracket 2 and a hollow groove 18 which is matched with the second pin shaft 12 to avoid the second pin shaft 12 when the bracket 2 moves, the track groove 17 and the hollow groove 18 are configured to make the first pin shaft 11 and the second pin shaft 12 be capable of penetrating through the bracket 2, both of the track groove 17 and the hollow groove 18 are arranged in a titling way towards the direction which is near to the tilting plate 3, the first pin shaft 11 and the second pin shaft 12 are respectively arranged within the track groove 17 and the hollow groove 18 in a penetrating way, and the bracket 2 is connected with an elastic reset device.

(36) The elastic reset device is a spring 19, one end of the spring 19 is connected with the bracket 2, and the other end of the spring 19 is connected with the base 1. Specifically, a cross rod 20 is arranged on the bracket 2, two ends of the cross rod 20 are fixedly connected with the two basal plates 6 of the bracket 2, the spring 19 is arranged in a tilting way, the upper end of the spring 19 hooks the cross rod 20, and the lower end of the spring 19 hooks the lower edge of the front end of the base 1. When in use, the 1-4 spring(s) 19 can be configured according to the actual requirement.

(37) As shown in FIG. 4, when the tilting plate 3 backwards overturns, the first pin shaft 11 and the second pin shaft 12 only move relative to the bracket rather than the base, the front end of the tilting plate 3 upwards pulls the first connecting rod 13 to upwards move, the third pin shaft 15 arranged at the hinge point between the first connecting rod 13 and the second connecting rod 14 pulls the bracket 2 to move towards the oblique upper direction which is near to the tilting plate 3, and the motion track of the bracket 2 is along the track groove 17; in the whole process of moving, the inclined angle between the second connecting rod 14 and the plumb line is always not more than 90 degrees, and the third pin shaft 15 is always arranged between the plumb line of the first pin shaft 11 and the plumb line of the second pin shaft 12.

(38) When the backrest or the tilting plate 2 tilts at the maximum angle, the distance that the bracket 2 or the chair backwards moves along with the backrest is 15-40 mm, 30 mm optimally; and the angle that the backrest backwards tilts is 10-30 degree, 21 degree optimally.

(39) As shown in FIG. 1, FIG. 2, FIG. 3, FIG. 5, FIG. 6 and FIG. 16, under the initial state, the users sit on the swivel chair, under the action of the pull force of the spring 19, the chair 36 and the gravity of the users, the support plate 7 presses onto the two supporting plates (not shown) of the base 1, and the basal plates 6 of the support 2 are completely arranged within the base 1; as shown in FIG. 17, when the users backwards to lean against the backrest 37, as shown in FIG. 1, FIG. 2, FIG. 3, FIG. 5, FIG. 6 and FIG. 17, the bracket 2 can drive the chair 36 linked, so that the chair 36 backwards moves along with the rotation of the backrest 37, in the process, taking the human back A and the human hip B as example, the human back A and the backrest 37 as well as the e human hip B and the chair 36 are always kept to be fixed rather than moved, so that the friction between the cloth and the human back can be avoided.

(40) As shown in FIG. 7 and FIG. 11, in order to lock the backrest at a proper position, the chassis is further provided with a backrest tilting plate locking mechanism, wherein the backrest tilting plate locking mechanism comprises a row of lock holes 21 which are symmetrically arranged on the two sides of the tilting plate 3, two torsion springs a22 symmetrically arranged on the two sides within the base 1, two plug pins 23 and two plug pin bases 24; the plug pin bases 24 are fixedly arranged on the base 1, the plug pins 23 are inserted onto the plug pin bases 24 in a sliding way and are matched with the lock holes 21, first spring arms 25 of the torsion springs a 22 are connected with the plug pins 23, and second spring arms 26 of the torsion springs a 22 are connected with a drive device used for driving the torsion springs a22 to rotate to and fro.

(41) As shown in FIG. 7-FIG. 13, the drive device comprises a crank 27, a positioning base 28 and a stirring rod 29, wherein the positioning base 28 is fixedly connected with the base 1, the positioning base 28 is arc and is hollow in the inner part, the upper end within the positioning base 28 is provided with an arc lug boss 30 which downwards extends, the lug boss 30 is configured to divide the upper end in the positioning base 28 into two positioning grooves 31, the positioning base 28 is internally provided with a fixture block 35, the fixture block 35 has the structure which is small in the upper part and large in the lower part, the sectional area of the fixture block 35 is gradually reduced from bottom to top, the bottom surface and the top surface of the fixture block 35 are arc, the upper end of the fixture block 35 is clamped within the positioning grooves 31, two ends of the crank 27 are connected with the second spring arms 26 of the two torsion springs a22, the crank 27 is connected with the fixture block 35 through a rocker 32, one end of the stirring rod 29 is fixedly connected with the fixture block 35 after penetrating through the support plates 5 of the base 1, and the other end of the stirring rod 29 exposes out of the base 1; the stirring rod 29 is stirred forward and backward, so that the fixture block 35 moves from one positioning groove 31 into another positioning groove 31, and the fixture block 35 rotates to drive the crank 27 move, therefore, the two torsion springs a22 are driven to rotate, and under the action of the elasticity of the torsion springs a22, the first spring arms 25 drive the plug pins 23 inserted into the corresponding lock holes 21 or be withdrawn out of the lock holes 21 to realize the lock and the unlock of the plug pins.

(42) The drive device further comprises two stand columns 33 for installing the torsion springs a22, the upper end of each stand column 33 is provided with a screw 39 in a screwing way, the torsion springs a22 are arranged onto the screws 39 in a covering way, the lower end of each stand column 33 is fixedly connected with the base plate 4 of the base 1 through arc bridges 34, a shaft hole 40 is formed between each arc bridge 34 and the bottom surface of the base 1, and the stirring rod 29 penetrates through one of the arc bridges to be fixed with the fixture block 35. Meanwhile, the chassis further comprises a press rod 38 used for controlling an air rod, wherein the press rod 38 is overlapped at the installing positron of the air rod after penetrating through the base and penetrating through another arc bridge.

(43) As shown in FIG. 8, under the state of unlock, the plug pin 23 departs from the lock holes 21, so that the users can lean against the backrest at any angles when sitting on the chair; as shown FIG. 9 and FIG. 13, under the state that the chair is under the initial position when not been leaned and locked, the stirring rod 29 is stirred, so that the upper end of the fixture block 35 overcomes the resistance of the lug boss 30 to move from the right positioning groove 31 to the left positioning groove 31, and the fixture block 35 rotates to drive the crank 27 move, therefore, the two torsion springs a22 are driven to move at the same time, and under the elastic function of the torsion springs a22, the first spring arm 25 pulls the plug pin 23 to be inserted into the corresponding lock holes 21 to lock the plug pin 23. When the backrest is needed to be adjusted into the proper position, the stirring rod 29 is stirred in the opposite direction, as shown in FIG. 8 and FIG. 12, so that the upper end of the fixture block 35 overcomes the resistance of lug boss 30 to move from the left positioning groove 31 to the right positioning groove 31, and the torsion springs a22 rotate to drive the plug pin 23 withdrawn out of the lock holes 21, meanwhile, the backrest can be leaned at the proper position, and when the proper position is needed to be kept, the action is repeated, so that the plug pin 23 is inserted into the corresponding lock holes 23 to be locked.

(44) FIG. 9 shows the situation that the plug pin 23 is inserted into the upmost insert hole to be locked when the backrest is not tilted; as shown in FIG. 10, when the backrest is under the maximum tilt angle and locked, the plug pin 23 is inserted into the bottommost insert hole.

(45) To clarify, the backrest tilting plate locking mechanism is not only limited by the mechanical mechanism but also can be locked at any position by the air rod; the elastic reset device can be a metal spring, the rubber spring or the air rod, and the combination of the metal spring, the rubber spring and the air rod.

(46) Embodiment 2: the difference between the embodiment 1 and the embodiment is as follows: as shown in FIG. 14 and FIG. 15, the second pin shaft 12 is two independent small shafts 41, two supports 42 are correspondingly fixed on the base 1, one end of each small shaft 41 is inserted into the second shaft hole 10 after penetrating the second connecting rod 14 and the hollow groove 18, and the other end of each small shaft 41 is inserted into the corresponding support 42. Therefore, relative to the mode of an integrated long shaft, the spring 19 can be avoided, and the baffle to the spring 19 can be avoided.

(47) Embodiment 3: the difference between the embodiment and the embodiment 1 is as follows: as shown in FIG. 18 and FIG. 19, the part of the basal plates 6 arranged at two sides of the bracket 2, which interferes the second shaft hole 10 and the second plug pin 12, is cut, so that the bracket avoids the second shaft hole 10 and the second plug pin 12, and the second plug pin 12 is directly inserted into the second shaft hole 10.

(48) Embodiment 4: the difference between the embodiment and the embodiment 1 is as follows: as shown in FIG. 20, the third pin shaft 15 is connected with the elastic reset device, the third pin shaft 15 is an integrated long shaft, the elastic reset device is the spring 19, one end of the spring 19 hooks onto the third pin shaft 15, and the other end of the spring 19 hooks the base plate 4 of the base 1.

(49) Embodiment 5: the difference between the embodiment and the embodiment 1 is as follows: as shown in FIG. 21, the elastic reset device is a torsion spring b43, the torsion spring b43 is arranged on the first pin shaft 11 in a covering way, the tilting plate 3 comprises two side plates 44 which are in parallel with each other at intervals and a connecting plate 45 which is connected with the two side plates 44 and the backrest, the connecting plate 45 is arranged outside the base, a baffle plate 46 is fixedly arranged on the base plate 4 of the base, one torsion arm 47 of the torsion spring b leans against the baffle plate 46, and the other torsion arm 48 of the torsion spring b leans against the connecting plate 45.

(50) Embodiment 6: the difference between the embodiment and the embodiment 1 is as follows: as shown in FIG. 22, the elastic reset device is a rubber spring 49 which is cylindrical in the whole, the rubber spring 49 comprises a rubber layer 50 which is circumferentially fixed onto the first plug pin 11, a cylindrical housing 51 is fixedly sleeved outside the rubber layer 50, a pair of connecting lugs 52 are fixedly arranged on the cylindrical housing 51, the first plug pin 11 is inserted into the first shaft hole and is fixedly connected with the base 1, the tilting plate 3 comprises two sides plates 44 which are in parallel with each other at intervals and a connecting plate 45 which is connected with the two sides plates 44 and connected with the backrest, the connecting plate 45 is arranged outside the base 1, a base body 53 is fixedly arranged on the connecting plate 45, and the connecting lugs 52 are hinged with the base body 53.

(51) Embodiment 7: the difference between the embodiment and the embodiment 1 is as follows: as shown in FIG. 23 and FIG. 24, the third pin shaft 15 is two independent short shafts, the fourth pin shaft 16 is an integrated long shaft, and two ends of the fourth pin shaft 16 are respectively connected with one end of the first connecting rod 13 and the front end of the tilting plate 3.

(52) Meanwhile, the fourth pin shaft 16 is connected with an elastic reset device, the elastic reset device is a spring 19, one end of the spring 19 is connected with the fourth pin shaft 16, and the other end of the spring 19 hooks the base 1, specifically, the position where the other end of the spring 19 is connected with the base 1 is arranged within the region of the back end of the base 1, which is far away from the first connecting rod 13 and the second connecting rod 14, a hook 54 is fixedly arranged at the region of the back end of the base 1, and the other end of the spring 19 hooks the hook 54.

(53) In order to avoid the noise caused by the contact of the metals, a plastic sleeve 55 is covered on the fourth pin shaft 16, one end of the spring 19 hooks onto the plastic sleeve 55, and the number of the springs 19 can be selected according to actual need.

(54) Embodiment 8: the difference between the embodiment and the embodiment 1 or the embodiment 2 is as follows: as shown in FIG. 23 and FIG. 24, the fourth pin shaft 16 is an integrated long shaft, and two ends of the fourth pin shaft 16 are respectively connected with one end of the first connecting rod 13 and the front end of the tilting plate 3.

(55) Meanwhile, the fourth pin shaft 16 is connected with an elastic reset device, the elastic reset device is a spring 19, one end of the spring 19 is connected with the fourth pin shaft 16, and the other end of the spring 19 hooks the base 1, specifically, the position where the other end of the spring 19 is connected with the base 1 is arranged within the region of the back end of the base 1, which is far away from the first connecting rod 13 and the second connecting rod 14, a hook 54 is fixedly arranged at the region of the back end of the base 1, and the other end of the spring 19 hooks the hook 54.

(56) In order to avoid the noise caused by the contact of the metals, a plastic sleeve 55 is covered on the fourth pin shaft 16, one end of the spring 19 hooks onto the plastic sleeve 55, and the number of the springs 19 can be selected according to the factors such as the damping factor, the room size and the like.

(57) As shown in FIG. 25-30, the structural form of the backrest tilting plate locking mechanism can be different, the backrest tilting plate locking mechanism comprises a lock plate 56, a torsion spring a22, a plug pin 23 and a plug pin base 24, wherein a row of lock holes 21 are arranged on the lock plate 56, the lock plate 56 is connected with an extension section 57 which is integrated with the lock plate 56 and is arranged on the same plane therewith, two ends of the extension section 57 are respectively connected with the first pin shaft 11 and the forth shaft pin 16 in a covering way, the extension section 57 is axially fixed relative to the forth plug pin 16, the lock plate 56 is arranged in the middle of the fourth pin shaft 16 or the position which is near to the middle, and the plane where the lock plate 56 is arranged is perpendicular to the axis of the forth plug pin 16.

(58) The extension section 57 is axially fixed relative to the fourth pin shaft 16, i.e. the relative displacement between the extension section 57 and the fourth pin shaft 16 can be avoided, in order to achieve the aim, the following two modes are adopted:

(59) As shown in FIG. 23, FIG. 25 and FIG. 26, the first mode is that the plastic sleeve 55 arranged on the fourth pin shaft 16 in a covering way is cut at the crossed position with the extension section 57 to form into a gap 58, and the extension section 57 is properly clamped within the gap 58.

(60) The second mode is that the intersected position between the extension section 57 and the fourth pin shaft 16 is fixed in a welding way.

(61) The plug pin base 24 is arranged beside the lock plate 56 and is fixedly connected with the base 1, the plug pin 23 is inserted onto the plug pin base 24 in a sliding way and is matched with the lock holes 21, a first spring arm 25 of the torsion spring a22 is connected with the plug pin 23, and a second spring arm 26 of the torsion spring a22 is connected with a drive device used for driving the torsion spring a22 to rotate back and forth.

(62) The drive device comprises a support base 59, a stirring rod 29 and a positioning ring 60 which is deformable once being forced, wherein the support base 59 is fixedly arranged on the plug pin base 24, the positioning ring 60 is fixedly arranged on the side wall of the support base 59, the torsion spring a22 is covered on the screw 39, the screw 39 is fixedly arranged on the support base 59, the positioning ring 60 is internally provided with kidney holes 61, the kidney holes 61 are arranged from top to bottom, an arc lug boss 30 is arranged in the middle of the kidney holes 61, the lug boss 30 is configured to divide the inner part of the positioning ring 60 into two clamp grooves 62, one end of the stirring rod 29 extends into the poisoning ring 60 in a bending way after penetrating through the base 1, and the other end of the stirring rod 29 exposes out of the base 1; the second spring arm 26 of the torsion spring a22 is connected with the end of the stirring rod 29, which extends into the positioning ring 60, the stirring rod 29 is rotated, so that the end of the stirring rod 29, which extends into the positioning ring 60, moves from one clamp groove 62 to another clamp groove 62, therefore, the torsion spring a22 is driven to rotate at the same time, and under the action of the elastic force of the torsion spring a22, the first spring arm 25 pulls the plug pin 23 to be inserted into the corresponding lock holes 21 or withdrawn out of the lock holes 21 to lock and unlock the plug pin 23.

(63) Furthermore, considering the fact that the space is limited and the position limit is carried out by the lock plate 56 maximally, as shown in FIG. 27 and FIG. 29, the upper end face 63a and the lower end face 63b of the lock plate 56 are concaved to form a gap groove 64 which is matched with the plug pin 23 in a leaning way, and the plug pin 23 outwards extends and is clamped within the gap groove 64 of the upper end face 63a and the lower end face 63b to lock the tilting plate 3 at the initial angle and the maximum angle.

(64) Certainly, the lower end face 63b can be configured to be horizontal, so that the lower end face 63b can be matched with the plug pin 23 in a leaning way.

(65) Embodiment 9: the difference between the embodiment and the embodiment 8 is as follows: the lock plate 56 can be also configured to be free of the extension section, and the lock plate 56 is fixedly connected with the fourth pin shaft 16 directly and moves along with the fourth pin shaft 16 simultaneously under the action of the tilting plate 3. The fixed connection between the lock plate 56 and the fourth pin shaft 16 can be 16 can be realized by the welding process or the integrated process.