CN212878495U

CN212878495U - Back seat linkage device for chair

Info

Publication number: CN212878495U
Application number: CN202021343066.8U
Authority: CN
Inventors: 虞红潮
Original assignee: UE Furniture Co Ltd
Current assignee: UE Furniture Co Ltd
Priority date: 2020-07-09
Filing date: 2020-07-09
Publication date: 2021-04-06
Anticipated expiration: 2030-07-09

Abstract

The utility model discloses a back seat linkage device for chairs, which comprises a base, a bracket and a wane; a front connecting piece is arranged between the front part of the bracket and the front end of the base, one end of the front connecting piece is hinged with the bracket at a first hinge point, and the other end of the front connecting piece is hinged with the base at a second hinge point; the rocker is connected to the rear end of the base, the front end of the rocker is provided with a rear connecting piece which is connected with the rocker into a whole, one end of the rear connecting piece is hinged to the third hinged point with the bracket, the other end of the rear connecting piece is hinged to the fourth hinged point with the base, and the rocker can rotate around the base through the rear connecting piece; the first hinge point, the second hinge point, the third hinge point and the fourth hinge point form a parallelogram four-point link mechanism; the first hinge point is higher than the third hinge point so that the front end of the bracket is higher than the rear end of the bracket; when the rear end of the rocker rotates downwards around the fourth hinge point, the bracket is lifted upwards synchronously, and in the process of lifting the bracket upwards, the inclination angle between the connecting line between the third hinge point and the first hinge point and the horizontal plane is kept unchanged.

Description

Back seat linkage device for chair

Technical Field

The utility model relates to a thing to sit on field, in particular to back of body seat aggregate unit for chair utensil.

Background

The chassis of the swivel chair, also called swivel chair tray, is an important part arranged below the seat cushion of the swivel chair, and the lifting of the seat cushion and the inclination angle adjustment of the backrest are all completed by the chassis. The present swivel chair tray is generally composed of an upper tray, a lower joist, a rotating shaft, a spring device and other parts, after the upper turntable is fixed with the back of a swivel chair seat, the swivel chair can properly tilt around the rotating shaft and can actively return, so that a user has comfortable feeling. For example, the chinese patent discloses a pallet (patent No. 02287885.8), which mainly comprises a bottom plate, a movable seat, a tapered tube and an adjusting device, wherein the movable seat is movably connected to the bottom plate, the middle of the movable seat is connected to the tapered tube of a pneumatic rod, and the tapered tube is welded to the movable seat together with a tapered tube fixing plate; the adjusting device comprises an adjusting rod, an adjusting plate, a torsion spring a and a torsion spring a fixing plate, the adjusting rod is inserted into the movable seat, the adjusting plate is fixedly connected to one end of the adjusting rod inserted into the movable seat, one surface of the adjusting plate is in contact with the air pressure rod, and the other surface of the adjusting plate is connected with the torsion spring a; the other side of the adjusting plate is provided with an adjusting plate rotation stopping sheet.

The adjusting device of the swivel chair tray is completely adjusted by the torsion spring, and for people with different weights, the force of the required torsion spring needs to be different, so that the product has no good universality. Therefore, a part of swivel chair chassis in the market at present forms force transmission by adopting a four-point link mechanism between a bracket and a wane, the middle part of the wane is a rotating fulcrum, the rear part of the wane is overturned under the action of a chair back, and the front part of the wane is hinged with the bracket through the link mechanism and pries the bracket upwards in an inclined way, so that the bracket and the wane form linkage; in the conduction structure, the chair back is connected and fixed on the warping plate as the driving force of the four-point linkage mechanism, the gravity applied to the chair seat by the human body forms the restoring force applied to the four-point linkage mechanism through the hinge point of the four-point linkage mechanism and the bracket, and the driving force and the restoring force of the four-point linkage mechanism form an antagonistic relation; therefore, the restoring force has less dependence on the elastic restoring force of the elastic restoring device, the applicable crowd range is wider, and people with lighter or heavier weight can easily lean and rise and restore.

However, most of the chassis adopting the four-bar linkage mechanism is set to be that when the chair back tilts backwards, the inclination angle of the cushion and the horizontal plane changes, and the front end of the cushion relative to the rear end can tilt upwards by a larger height, so that the front end of the cushion is higher than the rear end, which is beneficial to the recovery of a human body; however, the front end of the seat cushion is raised too obviously, and the front end of the seat cushion can press the thighs of a human body, so that the legs of the human body feel uncomfortable, and the use comfort is affected.

Disclosure of Invention

The utility model overcomes the defects in the prior art and provides a back seat linkage device for a chair, which adopts a four-point linkage mechanism to realize the linkage of the back seat and the seat of the chair; when the inclination angle of the chair back is increased, the chair seat can be synchronously lifted; the four-point linkage mechanism is a parallelogram, and the chair seat is set to be at a proper inclined position at an initial position, so that the front end of the chair seat is higher than the rear end; then, in the process of lifting the chair seat, the inclination angle between the chair seat and the horizontal plane is always unchanged; the front end of the chair seat is higher than the rear end of the chair seat, so that the human body can conveniently return, and meanwhile, the chair seat is lifted up and cannot push the thigh of the human body, and the use comfort is ensured.

The technical scheme of the utility model is realized like this:

a back seat linkage device for chairs comprises a base, a bracket for fixing a chair seat and a wane for connecting a chair back; a front connecting piece is arranged between the front part of the bracket and the front end of the base, one end of the front connecting piece is hinged with the bracket at a first hinge point, and the other end of the front connecting piece is hinged with the base at a second hinge point; the rocker is connected to the rear end of the base, the front end of the rocker is provided with a rear connecting piece which is connected with the rocker into a whole, one end of the rear connecting piece is hinged to the third hinge point with the bracket, the other end of the rear connecting piece is hinged to the fourth hinge point with the base, and the rocker can rotate around the base through the rear connecting piece; the front connecting piece, the bracket, the rear connecting piece and the base form a four-bar linkage, and a parallelogram is formed among the first hinge point, the second hinge point, the third hinge point and the fourth hinge point; in the initial position, the first hinge point is higher than the third hinge point so that the front end of the bracket is higher than the rear end of the bracket; when the rear end of the rocker rotates around the fourth hinge point, the four-point linkage mechanism is driven to move, the bracket is synchronously lifted or descended, and in the lifting or descending process of the bracket, the inclination angle between the connecting line between the third hinge point and the first hinge point and the horizontal plane is kept unchanged.

The first, second, third and fourth hinge points form a parallelogram four-point link mechanism to act on linkage between the bracket and the wane, so that the inclination angle of the bracket with the horizontal plane is kept unchanged all the time in the lifting process of the bracket, force application and transmission are facilitated, and actions among all components are smoother; the first hinge point is higher than the third hinge point, so that the front end of the bracket is higher than the rear end of the bracket at the initial position; preventing the human body from sliding forwards when in use, and being beneficial to the human body to reset when sitting and leaning upwards.

Preferably, the first hinge point and the third hinge point have the same height as each other during the lifting of the carriage, so that the front end of the carriage has the same height as the rear end of the carriage. The front end can not be obviously lifted relative to the rear end in the use process of the human body, and the human body thigh is prevented from being extruded.

Preferably, the bracket is connected above the base, a first pin shaft penetrates between the bracket and the front connecting piece, and a first hinge point is formed at the position of the axis of the first pin shaft; a second pin shaft penetrates between the base and the front connecting piece, and a second hinge point is formed at the position of the axis of the second pin shaft; the first pin shaft is parallel to the second pin shaft and is positioned in front of and above the second pin shaft.

Preferably, a third pin shaft penetrates between the bracket and the rear connecting piece, and a third hinge joint point is formed at the position of the axis of the third pin shaft; a fourth pin shaft penetrates between the base and the rear connecting piece, the rocker rotates around the base by taking the fourth pin shaft as a rotating shaft, and a fourth hinge point is formed at the position of the axis of the fourth pin shaft; the third pin shaft and the fourth pin shaft are arranged in parallel, and the third pin shaft is positioned in the front upper part of the fourth pin shaft.

Preferably, the inclination angle of the connecting line between the first hinge point and the third hinge point with respect to the horizontal plane is between 1.5 and 5 °. So that the inclination angle of the bracket and the horizontal plane is in a proper range and the human body does not feel uncomfortable.

Preferably, the rocker mechanism further comprises a limiting mechanism for limiting the rotation range of the rocker, the limiting mechanism comprises a limiting pin shaft and a limiting groove which is longitudinally arranged, and the limiting pin shaft penetrates through the limiting groove. Set up stop gear, the rotation range of restriction wane avoids the use range of the back of the chair too big, leads to the unstability.

Preferably, the limit pin shaft penetrates through the rear connecting piece, and two ends of the limit pin shaft respectively penetrate out of the rear connecting piece; the limiting groove is arranged at the corresponding position of the two sides of the base, and the part of the limiting pin shaft penetrating out of the rear connecting piece is positioned in the limiting groove.

Preferably, the rocker is provided with a locking mechanism for locking the rocker and the bracket, and the locking mechanism comprises a locking bolt arranged in the base in a penetrating way and a lock hole arranged on the bracket or the rocker; the locking bolt is inserted into the lock hole to realize the locking of the rocker and the bracket. When the locking mechanism is used by a human body, the chair back can be locked and stopped at any position.

Preferably, one end of the locking bolt is provided with a handle which is convenient for a human hand to hold, and the other end of the locking bolt is inserted into the base; a positioning seat used for keeping the locking bolt to move along the axial direction of the locking bolt is arranged in the base; the lock hole is arranged on one side corresponding to the rocker. The insertion can be operated through the handle, and the operation is simple and convenient.

Preferably, the device is further provided with an elastic reset device used for enabling the rocker and the bracket to be reset to the initial positions, and the elastic reset device is a tension spring; a first pin shaft penetrates between the front connecting piece and the bracket, and a third pin shaft penetrates between the rear connecting piece and the bracket; and two ends of the tension spring are respectively connected to the first pin shaft and the third pin shaft. When the spring is used by a human body, the damping feeling is good; and when the human body leaves the seat, the human body can reset automatically.

Preferably, the first hinge point is higher than the third hinge point by 5-11mm in the vertical direction, and the distance from the second hinge point to the fourth hinge point is the same as the distance from the first hinge point to the third hinge point.

Preferably, the first hinge point is located at a distance of 7-9mm above the third hinge point.

Adopted above-mentioned technical scheme the utility model discloses a design departure point, theory and beneficial effect are:

the four-point linkage mechanism is formed among the first pin shaft, the second pin shaft, the third pin shaft, the fourth pin shaft, the bracket, the wane and the base, and the four-point linkage mechanism is parallelogram; the lifting heights of the first pin shaft and the third pin shaft are consistent in the linkage process of the wane and the bracket, so that the lifting heights of the front end and the rear end of the bracket are the same; the chair seat is stably lifted, and the stability of the human body sitting on the chair seat is ensured.

Furthermore, the height of the first pin shaft is higher than that of the third pin shaft, so that in the initial position, the bracket is inclined to the horizontal plane, the front end of the bracket is high, and the rear end of the bracket is low; when the chair is used, the front end of the chair seat is a little higher, so that the human body is prevented from sliding forwards when leaning backwards; the front end of the bracket is upwarped, which is also beneficial to the recovery of the human body; in addition, because the four-point linkage mechanism is a parallelogram, namely the inclination angle of the bracket with the horizontal plane cannot be changed in the lifting process; when the bracket is lifted, the front end of the bracket is obviously lifted relative to the rear end of the bracket, and the inner side of a thigh is upwards extruded to influence the use comfort.

Furthermore, by means of the four-point linkage described above, a force transmission is formed; the chair back is connected and fixed on the warping plate and used as the driving force of the four-point connecting rod mechanism, the gravity applied to the chair seat by the human body is applied to the restoring force of the four-point connecting rod mechanism through the third pin shaft hinged to the bracket, and the driving force and the restoring force form countermeasures, namely the force applied to the chair back by the human body inclining backwards and leaning upwards and the self gravity form countermeasures; according to the weight of the human body, the backrest leaning and leaning restoring forces are correspondingly matched, so that people with light or heavy weight can easily lean forwards or backwards; the application range is wider and the application range is wider.

The chair seat is lifted along with the rotation of the chair back and moves backwards at the same time, so that the backrest lumbar support is always attached to the back of the human body, and the waist of the human body is prevented from being in a suspended state.

Drawings

Fig. 1 is a schematic perspective view of the linkage device according to an embodiment of the present invention;

fig. 2 is a schematic perspective view of another angle of the linkage according to the embodiment of the present invention;

fig. 3 is a schematic structural view of a bracket wane locking mechanism according to an embodiment of the present invention;

FIG. 4 is a schematic perspective view of the front and rear connecting members according to the embodiment of the present invention;

fig. 5 is a schematic side perspective view of the embodiment of the present invention after the bracket is lifted;

fig. 6 is a schematic sectional perspective view of the device in the initial position according to the embodiment of the present invention;

fig. 7 is a schematic sectional perspective view of the bracket of the device of the present invention after being lifted;

fig. 8 is a schematic diagram of the movement of the four-point link mechanism in the embodiment of the present invention;

fig. 9 is a schematic perspective view of a seesaw according to an embodiment of the present invention;

fig. 10 is a schematic perspective view of a base according to an embodiment of the present invention.

The figures are numbered: a base 1; a bracket 2; a seesaw 3; a front connecting piece 4; a connecting plate 4 a; a connecting side plate 4 b; a rear connector 5; a support plate 6; a bracket side plate 7; a bottom plate 8; a support plate 9; a first pin 10; a second pin 11; a mounting plate 12; side plates 13; a third pin 14; a fourth pin shaft 15; a first hinge point a; a second hinge point b; a third hinge point c; a fourth hinge point d; a four-point linkage A; the height h is raised; the inclination angle alpha; a limit pin 16; a limiting groove 17; a locking mechanism 18; a locking bolt 19; a lock hole 20; a handle 21; a positioning seat 22; a resetting device 23.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail with reference to the accompanying drawings and detailed description. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

In the description of the present invention, the term "at least one" means one or more unless explicitly defined otherwise. The terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The present embodiment relates to reference orientations of respective parts, such as front, rear, and the like, which are described in a normal use state after a user is seated.

The specific implementation manner of the utility model is as follows:

as shown in fig. 1-10, the present invention provides a back seat linkage device for a chair, comprising a base 1, a bracket 2 for connecting a seat, and a seesaw 3 for connecting a back of the chair; the bracket 2 is arranged at the upper end of the base 1, a front connecting piece 4 is arranged between the front part of the bracket 2 and the front end of the base 1, and two ends of the front connecting piece 4 are respectively hinged with the base 1 and the bracket 2; a rear connecting piece 5 is arranged between the rear part of the bracket 2 and the rear end of the base 1, and two ends of the rear connecting piece 5 are also hinged with the base 1 and the bracket 2 respectively; and, the wane 3 and this back connector 5 even as an organic whole, the wane 3 lies in the rear end of base 1, but the wane 3 can be around base 1 to rotate through this back connector 5 equally.

Specifically, the method comprises the following steps: as shown in fig. 1-5 and 10, the front connecting member 4 includes a connecting plate 4a and connecting side plates 4b extending upward along two sides of the connecting plate 4 a; as shown in fig. 1, the bracket 2 comprises a transverse bracket plate 6 and a bracket side plate 7 extending downwards along the inner side of the bracket plate 6; as shown in fig. 10, the base 1 includes a bottom plate 8 and support plates 9 extending upward in a vertical direction along left and right sides of the bottom plate 8; when the bracket is installed, the bracket 2 is placed in the bracket side plate 7, the bracket side plate 7 is positioned between the two supporting plates 9, and the front end of the bracket 2 protrudes out of the base 1; then the front connecting piece 4 is obliquely arranged to ensure that the upper end of the front connecting piece is matched with the bracket side plate 7 and the lower end of the front connecting piece is matched with the supporting plate 9; the connecting side plate 4b is positioned between the two bracket side plates 7; a first pin shaft 10 penetrates into one side of the bracket 2, and the first pin shaft 10 penetrates out of the other side of the bracket after sequentially penetrating through the bracket side plate 7 and the connecting side plate 4 b; the front of the front link 4 is hinged to the front of the bracket 2. The other end of the front connecting piece 4 is positioned between the two supporting plates 9, a second pin shaft 11 is introduced from one side of the base 1, and the second pin shaft 11 sequentially penetrates through the supporting plates 9 and the connecting side plate 4b and then penetrates out from the other side of the base 1; the front connection 4 is hinged with the front end of the base 1; and the first pin shaft 10 and the second pin shaft 11 are both a whole long shaft, and after the installation is finished, the lower end of the bracket side plate 7 can not interfere with the second pin shaft 11 all the time in the movement process of the bracket 2.

As shown in fig. 2-4 and 9, the rocker 3 comprises a mounting plate 12, and side plates 13 respectively extending upward along the left and right sides of the mounting plate 12; the side plate 13 is positioned between the two bracket side plates 7 of the bracket 2; the front part of the side plate 13 on the mounting plate 12 is positioned in the base 1, and the front part is the rear connecting piece 5, specifically: the upper part of the front end of the rear connecting piece 5 is matched with the bracket side plate 7, a third pin shaft 14 penetrates between the upper part and the bracket side plate 7, the third pin shaft 14 is a whole long shaft, the third pin shaft 14 penetrates into the bracket side plate 7 and the rear connecting piece 5 in sequence, the third pin shaft 14 penetrates out of the other side of the bracket 2 after penetrating through the bracket side plate 7 and the rear connecting piece 5, and when the bracket 2 rotates, two ends of the third pin shaft 14 cannot interfere with the supporting plates 9 on two sides of the base 1; the back lower extreme of back connecting piece 5 and base 1 between still worn fourth round pin axle 15, fourth round pin axle 15 be a whole major axis equally, the one end of fourth round pin axle 15 penetrates from base 1 one side, wears out from the opposite side of base after passing backup pad 9 and back connecting piece 5 in proper order, and in the motion process of bracket 2, the lower extreme of bracket curb plate 7 equally can not take place the contact with fourth round pin axle 15 between interfere.

As shown in fig. 6-8, the position of the first pin 10 is a first hinge point a, the position of the second pin 11 is a second hinge point b, the position of the third pin 14 is a third hinge point c, and the position of the fourth pin 15 is a fourth hinge point d; that is, a four-point link mechanism a is formed between the first hinge point a, the second hinge point b, the third hinge point c and the fourth hinge point d, and the bracket 2 and the rocker 3 are linked by the four-point link mechanism a, specifically: the base 1 is fixedly connected with the air rod, and the positions of the two hinge points b and the fourth hinge point d are kept relatively fixed; when the human body tilts backwards, the back end of the wane 3 rotates downwards around the fourth hinge point d by acting on the chair back, and the four-point link mechanism A is driven to enable the front connecting piece 4 and the rear connecting piece to rotate backwards; i.e. the carrier 2 is lifted.

It is important to point out that, as shown in fig. 6 and 8, in the initial position, the height of the first hinge point a is slightly higher than the third hinge point c, specifically, the height of the first hinge point a is 8mm higher than the third hinge point c; the second hinge point b is slightly higher than the fourth hinge point d and is also 8mm higher; the inclination angle α between the connecting line between the first hinge point a and the third hinge point c and the horizontal plane is between 1.5 ° and 5 °, specifically, 3.3 ° in this embodiment; the four-point linkage mechanism A is of a parallelogram structure; namely, the height of the first hinge point a is higher than that of the third hinge point c, so that the bracket 2 is in a slight inclination state without influencing the use of a human body with the horizontal plane at the initial position, and the front end of the bracket 2 is high and the rear end is low; when a human body sits on the chair seat in the initial position, the front end of the chair seat is slightly lifted; so that the human body is not easy to slide forwards in the using process; when the bracket 2 is lifted, as shown in fig. 7 and 8, because the four-point connecting mechanism a is a parallelogram, the lifting heights h of the first pin a and the third pin c are the same, that is, the lifting heights of the front end and the rear end of the bracket 2 after the bracket 2 is lifted are the same, and the inclination angle α between the connecting line between the first hinge point a and the third hinge point c and the horizontal plane is not changed, that is, the inclination angle between the bracket 2 and the horizontal plane is still kept unchanged; this enables the bracket 2 to be smoothly lifted without causing a sense of incongruity when a person sits thereon. After being different from other chassis devices, the bracket 2 is lifted, the front end of the bracket 2 is tilted relative to the rear end, so that the thighs of a human body are extruded, and the use comfort is affected.

As shown in fig. 2, 4 and 5, a limiting mechanism for limiting rotation of the rocker 3 is further disposed between the rear connecting member 5 and the supporting plate 9, the limiting mechanism includes a limiting pin 16 penetrating the rear connecting member 5 and a corresponding limiting groove 17 longitudinally disposed on the supporting plate 9, specifically: the limiting pin shaft 16 is positioned at the front end of the fourth pin shaft 15 and the lower end of the third pin shaft 14, two ends of the limiting pin shaft 16 respectively penetrate out of the rear connecting piece 5, and the penetrating part of the limiting pin shaft 16 is positioned in the limiting groove 17; as shown in fig. 6, in the initial position, the limit pin 16 abuts against the lower wall of the limit groove 17; when the chair back tilts backwards, the limiting pin shaft 16 moves upwards along the limiting groove 17; when the bracket 2 is raised to the maximum height, as shown in fig. 7, the limit pin 16 abuts against the upper wall of the limit groove 17.

As shown in fig. 2 and 3, the device is further provided with a locking mechanism 18 for rotationally locking the rocker 3 and the bracket 2 in the initial position, wherein the locking mechanism 18 comprises a locking bolt 19 and a locking hole 20; a handle 21 convenient for being held by a human hand is arranged at one end of the locking bolt 19, the other end of the locking bolt 19 is inserted into the base 1 from one side of the base 1, a positioning seat 22 is vertically arranged on the bottom plate 8 at the other side of the base 1, the locking bolt 19 is inserted into the positioning seat 22, so that the locking bolt 19 can be stably inserted and pulled along the axial direction of the locking bolt, and the lower end of the bracket side plate 7 cannot interfere with the locking bolt 19 in the movement process of the bracket 2; the locking hole 20 is correspondingly disposed on a side of the rocker 3 close to the positioning seat 22, and the locking hole 20 is configured to: when the rocker 3 is in the initial position, the locking bolt 19 can be inserted into the locking hole 20 to restrict the rotation of the rocker 3; when the chair back needs to be tilted, the control handle 21 makes the locking pin 19 leave the lock hole 20.

As shown in fig. 1 and 2, an elastic resetting device 23 for restoring the rocker 3 and the bracket 2 to the initial positions is further disposed between the second pin 11 and the third pin 14, and the elastic resetting device 23 is two tension springs; one end of the tension spring is connected to the second pin shaft 1, and the other end of the tension spring is connected to the third pin shaft 14; when the rocker 2 rotates and the bracket 2 is lifted, the tension spring is stretched to generate reset elasticity; and this elasticity resetting means 23 makes wane 2 provide human good damping sense at the rotation in-process, effectively gets rid of the rocking that assembly gap brought, abnormal sound scheduling problem.

Claims

1. A back seat linkage device for chairs is characterized by comprising a base, a bracket for fixing a chair seat and a wane for connecting a chair back; a front connecting piece is arranged between the front part of the bracket and the front end of the base, one end of the front connecting piece is hinged with the bracket at a first hinge point, and the other end of the front connecting piece is hinged with the base at a second hinge point; the rocker is connected to the rear end of the base, the front end of the rocker is provided with a rear connecting piece which is connected with the rocker into a whole, one end of the rear connecting piece is hinged to the third hinge point with the bracket, the other end of the rear connecting piece is hinged to the fourth hinge point with the base, and the rocker can rotate around the base through the rear connecting piece; the front connecting piece, the bracket, the rear connecting piece and the base form a four-bar linkage, and a parallelogram is formed among the first hinge point, the second hinge point, the third hinge point and the fourth hinge point; in the initial position, the first hinge point is higher than the third hinge point so that the front end of the bracket is higher than the rear end of the bracket; when the rear end of the rocker rotates around the fourth hinge point, the four-point linkage mechanism is driven to move, the bracket is synchronously lifted or descended, and in the lifting or descending process of the bracket, the inclination angle between the connecting line between the third hinge point and the first hinge point and the horizontal plane is kept unchanged.

2. The back-seat linkage for a chair according to claim 1, wherein: in the lifting process of the bracket, the lifting heights of the first hinge point and the third hinge point are the same, so that the lifting height of the front end of the bracket is the same as the lifting height of the rear end of the bracket.

3. The back-seat linkage for a chair according to claim 1, wherein: the bracket is connected above the base, a first pin shaft penetrates between the bracket and the front connecting piece, and a first hinge point is formed at the position of the axis of the first pin shaft; a second pin shaft penetrates between the base and the front connecting piece, and a second hinge point is formed at the position of the axis of the second pin shaft; the first pin shaft is parallel to the second pin shaft and is positioned in front of and above the second pin shaft.

4. The back-seat linkage for a chair according to claim 1, wherein: a third pin shaft penetrates between the bracket and the rear connecting piece, and a third hinge joint point is formed at the position of the axis of the third pin shaft; a fourth pin shaft penetrates between the base and the rear connecting piece, the rocker rotates around the base by taking the fourth pin shaft as a rotating shaft, and a fourth hinge point is formed at the position of the axis of the fourth pin shaft; the third pin shaft and the fourth pin shaft are arranged in parallel, and the third pin shaft is positioned in the front upper part of the fourth pin shaft.

5. The back-seat linkage for a chair according to claim 1, wherein: the inclination angle of the connecting line between the first hinge point and the third hinge point relative to the horizontal plane is 1.5-5 degrees.

6. The back-seat linkage for a chair according to claim 1, wherein: the mechanism comprises a limiting pin shaft and a limiting groove which is longitudinally arranged, and the limiting pin shaft penetrates through the limiting groove.

7. The back-seat linkage for a chair according to claim 6, wherein: the limiting pin shaft penetrates through the rear connecting piece, and two ends of the limiting pin shaft respectively penetrate out of the rear connecting piece; the limiting groove is arranged at the corresponding position of the two sides of the base, and the part of the limiting pin shaft penetrating out of the rear connecting piece is positioned in the limiting groove.

8. The back-seat linkage for a chair according to claim 1, wherein: the locking mechanism is used for locking the rocker and the bracket and comprises a locking bolt which is arranged in the base in a penetrating way and a lock hole which is arranged on the bracket or the rocker; the locking bolt is inserted into the lock hole to realize the locking of the rocker and the bracket.

9. The back-seat linkage for a chair of claim 8, wherein: one end of the locking bolt is provided with a handle which is convenient for being held by hands, and the other end of the locking bolt is inserted into the base; a positioning seat used for keeping the locking bolt to move along the axial direction of the locking bolt is arranged in the base; the lock hole is arranged on one side corresponding to the rocker.

10. The back-seat linkage for a chair according to claim 1, wherein: the device is also provided with an elastic reset device used for enabling the wane and the bracket to be restored to the initial positions, and the elastic reset device is a tension spring; a first pin shaft penetrates between the front connecting piece and the bracket, and a third pin shaft penetrates between the rear connecting piece and the bracket; and two ends of the tension spring are respectively connected to the first pin shaft and the third pin shaft.

11. The back-seat linkage for a chair according to claim 1, wherein: along the vertical direction, the first hinge point is higher than the third hinge point by 5-11mm, and the distance that the second hinge point is higher than the fourth hinge point is the same as the distance that the first hinge point is higher than the third hinge point.

12. The back-seat linkage for a chair according to claim 1, wherein: the first hinge point is 7-9mm higher than the third hinge point.