CN211722455U - Chair rack - Google Patents

Abstract

The invention discloses a chair frame, which comprises bottom feet, a fixed seat, a chair back frame, a chair seat frame, a first linkage frame and a second linkage frame, wherein the first linkage frame is fixedly connected with the bottom end of the chair back frame or is integrally formed and rotatably arranged on the fixed seat; the second linkage frame is fixedly connected with the bottom surface of the chair seat frame or integrally formed and movably arranged on the fixed seat; the device also comprises a left set of first connecting rod mechanisms, a right set of second connecting rod mechanisms, a left set of second limiting long holes, a right set of second limiting long holes, at least one second linkage rod and an electric push rod; when the chair back frame is inclined backwards, the chair seat frame moves backwards and upwards correspondingly, the chair seat frame moves downwards and forwards in the process of lifting the chair back frame, and the distance between the bottom of the chair back frame and the rear part of the chair seat frame is kept unchanged, so that the zero displacement effect is achieved, and the back rubbing phenomenon of the back of a human body and the back of a chair is avoided.

Description

Chair rack

Technical Field

The invention relates to the technical field of furniture, in particular to a chair frame.

Background

The comfort level of the chair is directly related to the working and life quality of people. More and more enterprises are studying seat-back linkage mechanisms to realize self-adaptive functions and improve the comfort of the seat.

The seat back linkage mechanism used by the existing seat on the market is complex in structure and high in production and processing difficulty, so that the cost is high; for example, chinese patent publication No. CN104223821B discloses a swivel chair chassis, which comprises a four-bar mechanism consisting of a plurality of links, a bracket and a base, wherein when a rocker connected to a backrest rotates, the bracket connected to a seat moves upward and backward as a whole, and the backrest tilting restoring force is correspondingly matched according to the weight of a human body, so that a person with no matter light or heavy weight can easily tilt and return to lift up; the chassis mechanism is mainly suitable for office chairs; for a leisure chair, a large-angle backward leaning rest is usually required, so that the front end of a chair seat is required to be tilted, and a seat-back linkage mechanism which is simple in structure and easy to process and manufacture needs to be researched to meet the market requirement.

Thus, chinese patent publication No. CN109984499A discloses a seat-back synchronous linkage device and a seat, including a base for connecting an air rod, a bracket for connecting a seat, and a rocker for connecting a backrest; the base, the bracket and the wane are connected through a first connecting rod, a second connecting rod and a third connecting rod to form a four-bar linkage; two sides of the lower end of the rocker extend forwards to form side plates, one end of the first connecting rod is hinged with the base and the rear part of the bracket, and the other end of the first connecting rod is hinged with the lower end of the rocker; one end of the third connecting rod is hinged with the front end of the base, and the other end of the third connecting rod is hinged with the front end of the side plate; one end of the second connecting rod is hinged with the bracket, and the other end of the second connecting rod is hinged with the middle part of the third connecting rod. When the rocker is driven by stress to send rotation, the front end of the bracket is driven to tilt under the action of the first connecting rod, the second connecting rod and the third connecting rod. The invention is assembled by adopting simple connecting rods, has simple structure, simple process and high stability, and greatly reduces the production cost.

However, in the process of using, those skilled in the art find that when the backrest is at a relatively large reclining angle, the included angle between the seat back and the horizontal plane is also at a relatively large state, so that the force of the human body on the chair is totally concentrated on the backrest, thereby causing the following problems:

1) the gravity centers of the human body and the chair move backwards, so that the chair is easy to tip backwards;

2) the backrest can bear larger acting force, so that the stability of the material and the structure of the backrest needs to be improved, and the production cost is improved;

3) correspondingly, the chair mainly provides the supporting force for the back of the human body through the backrest, the seat back only has the function of fixing the position of the human body to the buttocks of the human body and does not conform to the stress condition of the human body when the human body normally lies down, so that the human body is not in a comfortable state on the whole, and the human body can feel tired after the chair is supine for a long time.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide a seat frame in which a seat frame and a back frame are linked by a seat back and the seat frame does not rotate backward or rotates backward by a small angle when the back frame is at a relatively large backward tilt angle.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a chair frame comprises feet, a fixed seat, a chair back frame, a chair seat frame, a first linkage frame and a second linkage frame, wherein the fixed seat is fixedly connected with the feet; the second linkage frame is fixedly connected with the bottom surface of the chair seat frame or integrally formed and movably arranged on the fixed seat; further comprising:

the left and right sets of first connecting rod mechanisms are arranged on the fixed seat, the first linkage frame and the second linkage frame and comprise a first connecting rod, a second connecting rod and a third connecting rod which are sequentially hinged, the top end of the first connecting rod is rotatably arranged on the first linkage frame, the second connecting rod is in an inverted V shape and is rotatably arranged on the side surface of the fixed seat by taking a corner as a rotating circle center, and the top end of the third connecting rod is rotatably arranged on the side surface of the second linkage frame;

the left and right sets of second link mechanisms are arranged on the fixed seat and the second linkage frame and comprise a fifth connecting rod, a sixth connecting rod and a seventh connecting rod, the fifth connecting rod and the sixth connecting rod are rotatably arranged on the side face of the fixed seat, the bottom end of the fifth connecting rod is hinged with one end of the seventh connecting rod, the bottom end of the sixth connecting rod is hinged with the middle section of the seventh connecting rod, and the other end of the seventh connecting rod is hinged with the side face of the second linkage frame;

the top ends of the second limiting long holes are positioned behind the bottom ends of the second limiting long holes;

the second linkage rod is inserted into the second limiting long hole and is in clearance fit with the second limiting long hole;

the front end of the electric push rod is rotatably arranged on the fixed seat, and the other end of the electric push rod is rotatably arranged on the first linkage frame;

when the two second limiting long holes are respectively and symmetrically arranged on two side surfaces of the fixed seat, the second linkage rod is fixedly connected with the second linkage frame;

when the two second limit long holes are symmetrically arranged on two side faces of the second linkage frame respectively, the second linkage rod is fixedly connected with the fixed seat.

Preferably, the following is also provided:

the left and right arc-shaped concave first limiting long holes are positioned on the side surface of the fixed seat or the side surface of the second linkage frame;

the first linkage rods are inserted into the first limiting long holes and are in clearance fit with the first limiting long holes;

when the two first limiting long holes are respectively and symmetrically arranged on the two side faces of the fixing seat, the two ends of the two first linkage rods are respectively and fixedly connected with the two side faces of the first linkage frame, and when the two first limiting long holes are respectively and symmetrically arranged on the two side faces of the first linkage frame, the two first linkage rods are fixedly connected with the two side faces of the fixing seat.

Preferably, the fixing base front end is fixed with a horizontally first pipe, be fixed with the horizontally second pipe on the first linkage frame, still be equipped with two vertical first mounting panels that parallel and two vertical second mounting panels that parallel, first mounting panel bottom is articulated with first pipe joint and top and electric putter front end, second mounting panel top is articulated with second pipe joint and bottom and electric putter rear end.

Preferably, the second limiting long hole is linear, and the top end of the second limiting long hole faces backwards; the included angle range of the second limiting long hole and the horizontal plane is 30-60 degrees.

Preferably, the second limiting long hole is in an arc shape, and the top end of the second limiting long hole is positioned behind the bottom end of the second limiting long hole; and the included angle range between the straight line passing through the top end of the second limit long hole and the bottom end of the second limit long hole and the horizontal plane is 30-60 degrees.

Preferably, when the seat frame is at the lowest point, the top end of the sixth link is located forward of the bottom end of the sixth link, and the top end of the fifth link is located rearward of the bottom end of the fifth link.

Preferably, the first link mechanism further comprises an elastic member, a top end of the elastic member is connected with the hinge member and a bottom end of the elastic member is connected with the fixed seat, a bottom end of the elastic member is located in front of the top end of the elastic member, and when the seat frame is located at the lowest point, the elastic member is in a stretching state.

Further preferably, the first link includes at least one concave arc-shaped bent portion.

Preferably, the chair is further provided with a left hinged part and a right hinged part, the hinged parts are fixedly connected with the chair seat frame or the second linkage frame, and the hinged parts are hinged with the top end of the third connecting rod.

Preferably, the back frame is rotatable through an angle in the range of 0 ° to 60 °.

The invention has the technical effects that:

1) when the back of the chair frame topples over backward, the seat frame moves backward upwards, the distance between the bottom of the back of the chair frame and the rear part of the seat frame is kept unchanged all the time in the process of falling the back of the chair frame, correspondingly, in the process of rising the back of the chair frame, the seat frame moves downward forwards, the distance between the bottom of the back of the chair frame and the rear part of the seat frame is kept unchanged in the process of rising the back of the chair frame, and therefore the zero displacement effect is achieved, the back rubbing phenomenon of the back of the human body and the back of the chair is avoided, and people are assisted to lie down and get up through the electric push rod.

2) Through second link mechanism, the lift of chair seat frame is controlled to second linkage rod and second spacing groove, make the first half of chair seat frame along the spacing slot hole reciprocating motion of second in the lift in-process, it is reliable and stable to operate, and the seat support frame is at the little or even non-rotation of lift in-process turned angle, like this when the back of the chair frame is in great angle of lying backwards, the contained angle of chair seat frame and horizontal plane is still little with initial condition phase difference, the chair is still concentrated with human buttock to the holding power of human body like this, accord with the atress condition when the human body normally lies down, make the human body be in comfortable state, and reduced the distance that chair and human focus moved backwards, and then the stability of chair has been improved.

Drawings

FIG. 1 is a first schematic structural diagram of a chair frame according to an embodiment of the present invention;

FIG. 2 is a second schematic structural diagram of a chair frame according to an embodiment of the present invention;

FIG. 3 is a third schematic structural view of a chair frame according to an embodiment of the present invention (omitting the feet, the chair seat frame, the second linkage frame and the electric push rod);

fig. 4 is a schematic structural diagram of a chair frame according to an embodiment of the present invention (the foot, the chair seat frame and the chair back frame are omitted).

Description of reference numerals: 1. footing; 2. a fixed seat; 3. a back of chair frame; 4. a chair seat frame; 5. a first linkage frame; 6. a second linkage frame; 7. a first limit long hole; 8. a first linkage rod; 9. a second limit long hole; 10. a second linkage rod; 11. an electric push rod; 12. a first link; 13. a second link; 14. a third link; 15. an articulation member; 17. a fifth link; 18. a sixth link; 19. a seventh connecting rod; 20. a first tube; 21. a second tube; 22. a first mounting plate; 23. a second mounting plate.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "a plurality" means two or more unless explicitly defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The first embodiment is as follows:

as shown in fig. 1-4, a chair frame comprises a bottom foot 1, a fixed seat 2, a back frame 3, a chair seat frame 4, a first linkage frame 5 and a second linkage frame 6, wherein the fixed seat 2 is fixedly connected with the bottom foot 1, and the first linkage frame 5 is fixedly connected with the bottom end of the back frame 3 or integrally formed and rotatably mounted on the fixed seat 2; the second linkage frame 6 is fixedly connected with the bottom surface of the seat frame 4 or integrally formed and movably arranged on the fixed seat 2; further comprising:

the left and right sets of first connecting rod 12 mechanisms are arranged on the fixed seat 2, the first linkage frame 5 and the second linkage frame 6, the first connecting rod 12 mechanisms comprise a first connecting rod 12, a second connecting rod 13 and a third connecting rod 14 which are sequentially hinged, the top end of the first connecting rod 12 is rotatably arranged on the first linkage frame 5, the second connecting rod 13 is in an inverted V shape and is rotatably arranged on the side surface of the fixed seat 2 by taking a corner as a rotating circle center, and the top end of the third connecting rod 14 is rotatably arranged on the side surface of the second linkage frame 6;

the left and right sets of second connecting rod 13 mechanisms, the second connecting rod 13 mechanisms are installed on the fixed seat 2 and the second linkage frame 6 and comprise a fifth connecting rod 17, a sixth connecting rod 18 and a seventh connecting rod 19, the fifth connecting rod 17 and the sixth connecting rod 18 are rotatably installed on the side surface of the fixed seat 2, the bottom end of the fifth connecting rod 17 is hinged with one end of the seventh connecting rod 19, the bottom end of the sixth connecting rod 18 is hinged with the middle section of the seventh connecting rod 19, and the other end of the seventh connecting rod 19 is hinged with the side surface of the second linkage frame 6;

the top ends of the second limiting long holes 9 are positioned behind the bottom ends of the second limiting long holes 9;

the second linkage rod 10 is inserted into the second limiting long hole 9 and is in clearance fit with the second limiting long hole 9;

electric putter 11, the front end is rotatable installs on fixing base 2, and the other end is rotatable installs on first linkage 5.

When the two second limiting long holes 9 are respectively and symmetrically arranged on two side surfaces of the fixed seat 2, the second linkage rod 10 is fixedly connected with the second linkage frame 6;

when the two second limit long holes 9 are respectively and symmetrically arranged on two side surfaces of the second linkage frame 6, the second linkage rod 10 is fixedly connected with the fixed seat 2.

In the embodiment of the application, the method is further provided with:

the left and right arc-shaped concave first limiting long holes 7 are formed, and the first limiting long holes 7 are positioned on the side surface of the fixed seat 2 or the side surface of the second linkage frame 6;

the first linkage rods 8 are inserted into the first limiting long holes 7 and are in clearance fit with the first limiting long holes 7;

when the two first limit long holes 7 are respectively and symmetrically arranged on two side faces of the fixing seat 2, two ends of the two first linkage rods 8 are respectively and fixedly connected with two side faces of the first linkage frame 5, and when the two first limit long holes 7 are respectively and symmetrically arranged on two side faces of the first linkage frame 5, the two first linkage rods 8 are fixedly connected with two side faces of the fixing seat 2.

In this application embodiment, 2 front ends of fixing base are fixed with a horizontally first pipe 20, first pipe 20 is square pipe, be fixed with horizontally second pipe 21 on the first linkage 5, second pipe 21 is square pipe, still is equipped with two vertical first mounting panels 22 that parallel and two vertical second mounting panels 23 that parallel, first mounting panel 22 bottom and first pipe 20 fixed connection for example weld and the top is articulated with electric putter 11 front end, second mounting panel 23 top and second pipe 21 fixed connection for example weld and the bottom is articulated with electric putter 11 rear end. Preferably, a first rectangular notch is formed in the bottom end of the first mounting plate 22, the first rectangular notch is fixed to the front side (rear side) and the upper surface of the first tube 20 by welding, a second rectangular notch is formed in the top end of the second mounting plate 23, the second rectangular notch is fixed to the rear side (front side), the upper surface and the lower surface of the second tube 21 by welding, and the electric push rod 11 is rotatably mounted on the chair frame under the combined action of the first tube 20, the first mounting plate 22, the second tube 21, the second mounting plate 23 and the electric push rod 11; and the structure is stable, and the installation and the disassembly are convenient.

In the embodiment of the present application, two left and right hinge elements 15 are further provided, the hinge elements 15 are fixedly connected to the seat frame 4 or the second link frame 6, and the hinge elements 15 are hinged to the top end of the third connecting rod 14.

According to the arrangement, the back-of-chair frame 3 is stably and rotatably arranged on the fixed seat 2 through the part, connected with the first connecting rod 12, of the second connecting rod 13, the first connecting rod 12, the first limiting long hole 7, the first linkage frame 5 and the linkage rod; the rotatable angle range of the chair back frame 3 is 0-60 degrees through the first limit long hole 7;

the rising or falling power of the seat frame 4 is given through the portion of the second link 13 connected to the third link 14, the third link 14 and the hinge 15, and no restriction is made on the moving locus of the seat frame 4; thereby enabling the chair seat frame 4 to lift up and down along the second limit long hole 9.

In the embodiment of the present application, the second limiting long hole 9 is linear, and the top end of the second limiting long hole 9 faces rearward; the included angle range of the second limiting long hole 9 and the horizontal plane is 30-60 degrees, and further preferably, the included angle range of the second limiting long hole 9 and the horizontal plane is 40-50 degrees.

It is worth to be noted that the second limiting long hole 9 can also be an arc line type, and the top end of the second limiting long hole 9 is located behind the bottom end of the second limiting long hole 9; and the included angle between the straight line passing through the top end of the second limit long hole 9 and the bottom end of the second limit long hole 9 and the horizontal plane ranges from 30 degrees to 60 degrees, and further preferably, the included angle between the straight line and the horizontal plane ranges from 40 degrees to 50 degrees.

In the embodiment of the present application, during the ascending process of the seat frame 4, the height of the seventh connecting rod 19 that is rotated upward by the end hinged to the second link frame 6 is greater than the height of the seventh connecting rod 19 that is rotated downward by the end hinged to the second link frame 6; further preferably, during the ascending process of the seat frame 4, one end of the seventh connecting rod 19 hinged to the second link frame 6 rotates upwards; namely, by adjusting the positions and sizes of the fifth link 17 and the sixth link 18, the movement locus of the end of the seven links hinged to the second link frame 6 can be adjusted.

In the present embodiment, when the seat frame 4 is at the lowest point, the top end of the sixth link 18 is located forward of the bottom end of the sixth link 18, and the top end of the fifth link 17 is located rearward of the bottom end of the fifth link 17.

Preferably, the first link 12 mechanism further comprises an elastic member, a top end of the elastic member is connected with the hinge member 15 and a bottom end of the elastic member is connected with the fixed seat 2, the bottom end of the elastic member is located in front of the top end of the elastic member, and when the seat frame 4 is located at the lowest point, the elastic member is in a stretching state; further preferably, the elastic member is a spring, and the seat frame 4 moves more stably by the spring.

Further preferably, the first connecting rod 12 at least comprises a concave arc-shaped bent part; in the process of the linkage movement of the back frame 3 and the seat frame 4, the first connecting rod 12 is a stress rod, and the structural strength of the first connecting rod 12 can be improved by arranging a concave arc-shaped bending part.

In the embodiment of the present application, the backrest frame 3 includes an upwardly convex arc-shaped bending portion, and the upwardly convex arc-shaped bending portion is located at the middle section of the backrest frame 3; so set up and accord with human back curve, the arc flexion of this epirelief forms effective support to human waist, helps slowing down human fatigue degree.

In the embodiment of the application, a telescopic rod is further arranged, the bottom end of the telescopic rod is fixedly connected with the bottom foot 1, and the fixed seat 2 is fixed at the top end of the telescopic rod.

The specific motion process of the chair frame is as follows:

when the electric push rod 11 extends, the first linkage rod 8 is driven to move from the front end to the rear end of the first limiting long hole 7, so that the back frame 3 rotates upwards, meanwhile, the first connecting rod 12 moves backwards, the second connecting rod 13 is pulled to rotate, the third connecting rod 14 moves downwards in the rotating process, and the seat frame 4 is driven to move downwards;

in the process of moving the seat frame 4 downwards, the seat frame 4 descends and moves forwards along the second limit long hole 9 through the combined action of the second connecting rod 13 mechanism, the second linkage rod 10 and the second limit long hole 9;

when the electric push rod 11 is shortened, the first linkage rod 8 is driven to move from the rear end to the front end of the first limiting long hole 7, so that the back frame 3 rotates downwards, meanwhile, the first connecting rod 12 moves forwards, the second connecting rod 13 is pushed to rotate, the third connecting rod 14 rises in the rotating process, and the seat frame 4 is driven to rise;

during the process of the seat frame 4 rising, the seat frame 4 can only rise and move backwards along the second limit long hole 9 through the combined action of the second link 13 mechanism, the second link rod 10 and the second limit long hole 9.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the principles and spirit of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A chair frame comprises bottom feet (1), a fixed seat (2), a chair back frame (3), a chair seat frame (4), a first linkage frame (5) and a second linkage frame (6), wherein the fixed seat (2) is installed on the bottom feet (1), and the first linkage frame (5) and the bottom end of the chair back frame (3) are fixedly connected or integrally formed and rotatably installed on the fixed seat (2); the second linkage frame (6) is fixedly connected with the bottom surface of the chair seat frame (4) or integrally formed and movably arranged on the fixed seat (2); it is characterized by also comprising:

the left and right sets of first connecting rod (12) mechanisms are arranged on the fixed seat (2), the first linkage frame (5) and the second linkage frame (6) and comprise a first connecting rod (12), a second connecting rod (13) and a third connecting rod (14) which are sequentially hinged, the top end of the first connecting rod (12) is rotatably arranged on the first linkage frame (5), the second connecting rod (13) is inverted V-shaped and is rotatably arranged on the side surface of the fixed seat (2) by taking a corner as a rotating circle center, and the top end of the third connecting rod (14) is rotatably arranged on the side surface of the second linkage frame (6);

the left and right sets of second connecting rod (13) mechanisms are arranged on the fixed seat (2) and the second linkage frame (6) and comprise a fifth connecting rod (17), a sixth connecting rod (18) and a seventh connecting rod (19), the fifth connecting rod (17) and the sixth connecting rod (18) are rotatably arranged on the side surface of the fixed seat (2), the bottom end of the fifth connecting rod (17) is hinged with one end of the seventh connecting rod (19), the bottom end of the sixth connecting rod (18) is hinged with the middle section of the seventh connecting rod (19), and the other end of the seventh connecting rod (19) is hinged with the side surface of the second linkage frame (6);

the top ends of the second limiting long holes (9) are positioned behind the bottom ends of the second limiting long holes (9);

the second linkage rod (10) is inserted into the second limiting long hole (9) and is in clearance fit with the second limiting long hole (9);

the front end of the electric push rod (11) is rotatably arranged on the fixed seat (2), and the other end of the electric push rod is rotatably arranged on the first linkage frame (5);

when the two second limiting long holes (9) are respectively and symmetrically arranged on two side surfaces of the fixed seat (2), the second linkage rod (10) is fixedly connected with the second linkage frame (6);

when the two second limit long holes (9) are respectively and symmetrically arranged on two side surfaces of the second linkage frame (6), the second linkage rod (10) is fixedly connected with the fixed seat (2).

2. A chair frame according to claim 1, further comprising:

the left and right arc-shaped concave first limiting long holes (7), and the first limiting long holes (7) are positioned on the side surface of the fixed seat (2) or the side surface of the second linkage frame (6);

the linkage device comprises at least two first linkage rods (8) which are parallel, wherein the first linkage rods (8) are inserted into first limiting long holes (7) and are in clearance fit with the first limiting long holes (7);

when the two first limiting long holes (7) are symmetrically arranged on two side faces of the fixing seat (2) respectively, two ends of the two first linkage rods (8) are fixedly connected with two side faces of the first linkage frame (5) respectively, and when the two first limiting long holes (7) are symmetrically arranged on two side faces of the first linkage frame (5) respectively, the two first linkage rods (8) are fixedly connected with two side faces of the fixing seat (2).

3. The chair frame according to claim 1, characterized in that a horizontal first pipe (20) is fixed at the front end of the fixed seat (2), a horizontal second pipe (21) is fixed on the first linkage frame (5), a first mounting plate (22) and a second mounting plate (23) are further arranged, the bottom end of the first mounting plate (22) is fixedly connected with the first pipe (20), the top end of the first mounting plate is hinged with the front end of the electric push rod (11), and the top end of the second mounting plate (23) is fixedly connected with the second pipe (21), and the bottom end of the second mounting plate is hinged with the rear end of the electric push rod (11).

4. A chair frame according to claim 1, characterized in that the second limiting long hole (9) is linear, and the top end of the second limiting long hole (9) faces rearward.

5. The chair frame according to claim 1, wherein the second limiting long hole (9) is arc-shaped, and the top end of the second limiting long hole (9) is positioned at the rear of the bottom end of the second limiting long hole (9).

6. A chair frame according to claim 1, characterised in that when the seat frame (4) is at its lowest point, the top end of the sixth link (18) is located forward of the bottom end of the sixth link (18) and the top end of the fifth link (17) is located rearward of the bottom end of the fifth link (17).

7. A chair frame according to claim 1, characterised in that the first linkage (12) mechanism further comprises a resilient member having a top end connected to the hinge member (15) and a bottom end connected to the fixed seat (2), the bottom end of the resilient member being located forward of the top end of the resilient member, the resilient member being in tension when the seat frame (4) is at its lowest point.

8. A chair frame according to claim 1, characterised in that said first link (12) comprises at least one concavely curved portion.

9. A chair frame according to claim 1, characterized in that, a left and a right hinged parts (15) are provided, the hinged parts (15) are fixedly connected with the chair seat frame (4) or the second linking frame (6), and the hinged parts (15) are hinged with the top end of the third connecting rod (14).

10. A chair frame according to claim 1, characterised in that the backrest frame (3) is rotatable through an angle in the range 0 ° to 60 °.

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