CN214760154U - Chair frame - Google Patents

Abstract

The utility model discloses a chair frame, which comprises a chair back, a chair seat, chair feet and a chair chassis, wherein the chair chassis comprises a first connecting seat, a chassis seat, a second connecting seat, a third connecting seat and a torsion adjusting mechanism, the torsion adjusting mechanism comprises a swinging block, a screw rod and a torsion spring, a mandrel is arranged at one end of the swinging block in a penetrating way, the torsion spring is sleeved on the mandrel, and the second connecting seat and the chassis seat are hinged through the mandrel; the other end of the swinging block is fixedly connected with or integrally formed with a torsion adjusting block, the upper end of the torsion adjusting block is provided with a push block, and a screw penetrates through the push block and is connected with the push block; one end of the torsion spring is movably arranged at the lower end of the torsion adjusting block and endows the torsion adjusting block with a tendency of moving towards the direction of the pushing block, the screw rod rotates to drive the pushing block to move horizontally, and the pushing block moves horizontally to drive the torsion adjusting block to move up and down, so that the swinging amplitude of the second fixing seat is adjusted, and the elasticity of the chair back frame and the chair seat frame is adjusted.

Description

Chair frame

Technical Field

The utility model relates to the technical field of seats, concretely relates to chair frame.

Background

The chair is an indispensable furniture for people to work or rest, and plays a role in bearing the weight of people. Along with the improvement of living standard of people, the requirement on the comfort of the seat is higher and higher, and the back of the chair of the existing seat can rotate to different angles in a front-back mode relative to the base so as to improve the comfort of use. The seat chassis of the seat with the seat lifting function, the seat tilting function and the seat back tilting function generally comprises a middle plate group connected with a pneumatic rod, a flip cover connected with the seat back and a big plate group connected with the seat, and a reset torsion spring for resetting is generally arranged on a pivot connecting the big plate group and the middle plate group and a pivot connecting the flip cover and the big plate group. After a certain usage time, the torsion of the reset torsion spring changes to a certain degree, and if the torsion of the reset torsion spring is weakened, the functions of lifting the chair, inclining the chair seat, inclining the chair back and the like are further influenced. In the prior art, a mechanism for adjusting the torsion force of the return torsion spring is provided in the seat chassis of a partial seat, but there are still some disadvantages, including the following:

1. when the torsion of the reset torsion spring is adjusted, the torsion can be realized only by a large external force;

2. when the torsion of the torsion spring is fixed, a locking member is required, and the operation is complicated.

Patent document that the publication number is CN203576041U discloses a chair tray torsional spring torsion adjustment mechanism, locates the epaxial reset torsion spring of chair tray pivot including shell, chair tray pivot and cover, still includes the locating piece, cam and regulation pole, reset torsion spring one end is equipped with the L type bending segment, L type bending segment and locating piece looks butt, the locating piece is contradicted with the cam cambered surface with the opposite side that the L type bending segment was contradicted to be connected relatively and is connected, adjust pole and cam fixed connection and control cam circumferential direction, the locating piece is the cambered surface with the face of L type bending segment butt, aims at providing one kind and can adjust the chair tray torsional spring torsion adjustment mechanism of the operation of being convenient for use to reset torsion spring torsion. The adjusting mechanism adjusts the torsion of the torsion spring by rotating the cam and extruding the positioning block, and needs strong external force; in addition, the torsion of the torsion spring is fixed by matching the annular clamping teeth with the annular clamping tooth holes, and the operation is complex.

Patent document with publication number CN206324514U discloses a swivel chair tray torsion spring adjusting mechanism, which comprises a base, a middle seat and a rocker, wherein the middle seat is internally provided with a triangular push block, the triangular push block is connected with a transmission mechanism, the inclined surface of the triangular push block is contacted with a torsion spring adjusting block, one end surface of the torsion spring adjusting block is provided with a contact surface matched with the inclined surface of the triangular push block, the other end of the torsion spring adjusting block is connected with a torsion spring, and the torsion spring is connected with the middle seat. This adjustment mechanism passes through adjusting screw and promotes the triangle ejector pad and remove, triangle ejector pad drive torsional spring regulating block takes place the displacement and then realizes torsional spring torsion's regulation, however, the atress through to the torsional spring regulating block carries out the analysis, we can discover, the torsional spring regulating block receives the effort of two directions, including the power that is on a parallel with torsional spring regulating block direction of motion, and the power of perpendicular to torsional spring regulating block direction of motion, the former promotes the torsional spring regulating block and moves to the torsional spring direction, the latter has increased the frictional force between torsional force regulating block and the base, when the torsion of regulation torsional spring, need stronger external force, influence user's experience.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problem, the utility model aims at providing a chair frame, the seat chassis on this chair frame need not realize the regulation of torsional spring torsion with the help of other locking mechanism, and its operation is fairly simple and laborsaving.

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

a chair frame comprises a chair back frame, a chair seat frame, a chair base and chair feet, wherein the chair back frame and the chair seat frame are fixedly connected or integrally formed, the chair seat frame is connected with the chair feet through the chair base, the chair base comprises a first connecting seat, a chassis seat, a second connecting seat, a third connecting seat and a torsion adjusting mechanism, the chair feet are fixedly connected below the chassis seat, the lower portion of the first connecting seat is hinged with the front portion of the chassis seat, the lower portion of the second connecting seat is hinged with the rear portion of the chassis seat, the third connecting seat is positioned above the chassis seat and is simultaneously fixedly connected with the lower portion of the first connecting seat and the lower portion of the second connecting seat, the torsion adjusting mechanism is installed in the chassis seat and controls the chair back frame and the chair seat frame to synchronously swing, the upper portion of the first connecting seat is hinged with the front portion of the chair seat frame, the upper portion of the second connecting seat is hinged with the rear portion of the chair seat frame, the first connecting seat, the second connecting seat is connected with the chair back frame, the chair seat and the chair feet, The chair seat frame, the second connecting seat and the chassis seat form a four-bar mechanism, the torsion adjusting mechanism comprises a swinging block, a screw rod and at least one torsion spring, one end of the swinging block is provided with a mandrel in a penetrating way, the swinging block rotates relative to the mandrel, the torsion spring is sleeved on the mandrel, and the second connecting seat and the chassis seat are hinged through the mandrel; the other end of the swinging block is fixedly connected with or integrally formed with a torsion adjusting block, the upper end of the torsion adjusting block is provided with a push block, and a screw rod penetrates through the push block and is in threaded connection with the push block; one end movable mounting of torsional spring is at the lower extreme of torsion regulating block and gives the trend of torsion regulating block to ejector pad direction motion, and the screw rod rotates and drives ejector pad horizontal motion, and ejector pad horizontal motion impels the torsion regulating block to carry out the up-and-down motion, and the torsion regulating block is then the compression or lax torsional spring to adjust the swing range of second connecting seat.

Preferably, a first inclined plane is formed on the upper end surface of the torsion adjusting block, and a second inclined plane which is abutted against the first inclined plane is formed on the lower end surface of the pushing block.

Preferably, the torsion adjusting mechanism further comprises a limiting block arranged below the torsion adjusting block, a first groove used for limiting the torsion adjusting block up and down and accommodating the torsion adjusting block is formed in the limiting block, and a limiting plate part extends upwards from one end, far away from the torsion spring, of the limiting block; a second groove which is used for the sliding of the push block and is matched with the bottom shape of the push block is further formed in one side, located on the first groove, of the limiting block. Spacing board portion and second recess cooperate and are used for carrying out circumference spacing to the ejector pad, avoid it to take place circumferential direction.

Preferably, one end of the screw is provided with a driving mechanism for driving the screw to rotate, the driving mechanism comprises a handle and at least two gears, the gears are meshed with each other, a first gear is fixed on the handle, one end, close to the limiting block, of the handle is rotatably connected with the limiting block, a second gear is fixed on the screw, and the first gear is directly meshed with the second gear or is indirectly meshed with the second gear through at least one gear in a transmission mode. The screw rod is driven to rotate through the transmission of the gear, and the operation is labor-saving.

Preferably, in the horizontal direction, the second inclined plane of the push block inclines from top to bottom along the left-to-right direction, the second inclined plane is in a twisted shape, and the right end edge of the push block inclines from back to front to top to bottom; in the horizontal direction, the first inclined plane of torsion regulating block is followed from left to right direction and is from top to bottom inclined, and first inclined plane is the distortion form, and the right-hand member of torsion regulating block is followed from the backward place ahead to from top to bottom inclined. The big gear wheel on the handle drives the small gear wheel on the screw rod to rotate, and the torsion of the torsion spring can be adjusted only by rotating the handle in a small range.

Preferably, a third groove is formed in the middle of the upper end of the torque force adjusting block; and a fourth groove is formed in the middle of the lower end of the push block. The probability that the side edge of the torque force adjusting block is abutted to the inclined surface of the push block is reduced, and the inclined surface can be well protected.

Preferably, two support columns extend along the axial direction of the mandrel from one end of the swinging block, which is far away from the torsion adjusting block, the support columns are sleeved on the mandrel, and the outer diameter of each support column is smaller than or equal to the inner diameter of the torsion spring. Avoid the torsional spring atress to take place the distortion when great, and then can protect the torsional spring.

Preferably, an arc-shaped groove is formed in the position, in contact with the torsion spring, of the torsion adjusting block, and one end of the torsion spring is movably installed at the lower end of the torsion adjusting block and embedded into the arc-shaped groove. The setting of arc recess can play spacing effect to the torsional spring, avoids it to take place the displacement of horizontal direction.

Preferably, the swing block comprises two torsion springs, wherein the two torsion springs are sleeved on the mandrel and are respectively arranged on two opposite sides of the swing block. The stress of the acted part is increased, and the stress is more uniform.

Preferably, the chair frame further comprises a chair back support frame, one end of the chair back support frame is fixedly connected with the rear part of the second connecting seat, and the other end of the chair back support frame is fixedly connected with the chair back frame. Thus, the chair back frame is supported and reinforced, and the chair back frame is prevented from being damaged due to large stress when in use.

The utility model discloses owing to adopted above technical scheme to have following beneficial effect:

1. in the chair frame of the utility model, the push block is horizontally moved by rotating the screw rod, the torsion adjusting block moves up and down under the action of the push block, and further, the torsion of the torsion spring is changed by the torsion adjusting block;

2. when the torsion of the torsion spring is locked, other locking mechanisms are not needed;

3. the screw rod is driven to rotate through the transmission action of the gear, and the operation is labor-saving.

Drawings

FIG. 1 is a schematic structural diagram of a torsion adjusting structure of a torsion spring;

FIG. 2 is a schematic structural view of a torsion adjusting structure of a torsion spring with a limiting block;

FIG. 3 is a bottom view of FIG. 1;

FIG. 4 is a schematic diagram of a wobble block;

FIG. 5 is a schematic structural view of the push block;

FIG. 6 is a schematic diagram of another view of a wobble block;

FIG. 7 is a schematic structural diagram of a limiting block;

FIG. 8 is a schematic structural view of the seat chassis with the torsion adjusting structure of the torsion spring mounted thereon;

FIG. 9 is a bottom view of FIG. 8;

fig. 10 is a schematic structural view of the present invention;

fig. 11 is a schematic view of another angle of the present invention;

reference numerals: 1. a swing block; 2. a screw; 3. a torsion spring; 4. a mandrel; 5. a torque force adjusting block; 6. a push block; 7. an arc-shaped groove; 8. a limiting block; 9. a first groove; 10. a limit plate part; 11. a second groove; 12. a handle; 13. a first gear; 14. a second gear; 15. a third groove; 16. a fourth groove; 17. a support pillar; 18. a first connecting seat; 19. a chassis base; 20. a second connecting seat; 21. a third connecting seat; 22. a seat pan; 23. a back of chair frame; 24. a chair seat frame; 25. a chair back support frame; 26. a handrail.

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 or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and to simplify the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention.

As shown in fig. 1 to 11, a seat frame includes a back frame 23, a seat frame 24, a seat pan 22 and seat legs, the back frame 23 and the seat frame 24 are fixedly connected or integrally formed, the seat frame 24 is connected with the seat legs through the seat pan 22, the seat pan 22 includes a first connecting seat 18, a chassis seat 19, a second connecting seat 20, a third connecting seat 21 and a torsion adjusting mechanism, the seat legs are fixedly connected below the chassis seat (19) through support rods, the lower portion of the first connecting seat 18 is hinged with the front portion of the chassis seat 19, the lower portion of the second connecting seat 20 is hinged with the rear portion of the chassis seat 19, the third connecting seat 21 is positioned above the chassis seat 19 and is fixedly connected with the lower portion of the first connecting seat 18 and the lower portion of the second connecting seat 20, of course, the second connecting seat 20 may be integrally formed with the third connecting seat 21, the torsion adjusting mechanism is installed in the chassis seat 19 and controls the back frame 23 and the seat frame 24 to synchronously swing, the upper part of the first connecting seat 18 is hinged with the front part of the seat frame 24, the upper part of the second connecting seat 20 is hinged with the rear part of the seat frame 24, and the first connecting seat 18, the seat frame 24, the second connecting seat 20 and the chassis seat 19 form a four-bar linkage. In this embodiment, the chair frame further includes a chair back support frame 25, one end of the chair back support frame 25 is fixedly connected with the rear portion of the second connecting seat 20, and the other end of the chair back support frame 25 is fixedly connected with the chair back frame 23. Thus, the chair back frame is supported and reinforced, and the chair back frame is prevented from being damaged due to large stress when in use. Preferably, handrails 26 for a user to conveniently place his/her hand may be fixedly provided at both sides of the second coupling seat 20.

As shown in fig. 1 to 5, the torque force adjusting mechanism includes a swing block 1, a screw rod 2 and at least one torsion spring 3, a spindle 4 is disposed at one end of the swing block 1 in a penetrating manner, the swing block 1 can rotate relative to the spindle 4, the torsion spring 3 is sleeved on the spindle 4, and a second connecting seat 20 is hinged to the chassis seat 19 through the spindle 4; the other end of the swinging block 1 is fixedly connected with or integrally formed with a torsion adjusting block 5, the upper end of the torsion adjusting block 5 is provided with a push block 6, and the screw rod 2 penetrates through the push block 6 and is in threaded connection with the push block 6; the upper end face of torsion regulating block 5 forms first inclined plane, and the lower terminal surface of ejector pad 6 forms the second inclined plane that offsets with first inclined plane, the one end movable mounting of torsional spring 3 is at the lower extreme of torsion regulating block 5 and gives the trend of torsion regulating block 5 to the motion of ejector pad 6 direction, and is concrete, and arc recess 7 has been seted up with the position of torsional spring 3 contact on the torsion regulating block 5, and the one end of torsional spring 3 compresses tightly in the lower extreme of torsion regulating block 5 and imbeds arc recess 7, and swing piece 1 is when rotating, and the position embedding arc recess 7 that is close to torsion regulating block 5 on the torsional spring 3 is spacing in arc recess 7, and the setting of arc recess 7 can play spacing effect to torsional spring 3, avoids it to take place the displacement of horizontal direction. The screw 2 rotates to drive the pushing block 6 to move horizontally, the pushing block 6 moves horizontally to drive the torsion adjusting block 5 to move up and down, and the torsion adjusting block 5 further compresses or relaxes the torsion spring 3, so that the swing amplitude of the second connecting seat 20 is adjusted, and the swing amplitudes of the back frame 23 and the seat frame 24 are adjusted. Preferably, the swing block comprises two torsion springs 3, wherein the two torsion springs 3 are sleeved on the mandrel 4 and are respectively arranged on two opposite sides of the swing block 1, so that the stress of the acted part can be increased, and the stress of the acted part is more uniform. The push block 6 moves horizontally by rotating the screw rod 2, the torsion adjusting block 5 moves up and down under the action of the push block 6, further, the torsion adjusting block 5 changes the torsion of the torsion spring 3, when the torsion adjusting block 5 moves up under the action of the push block 6, the torsion of the torsion spring 3 is enhanced, and when the torsion adjusting block 5 moves down under the action of the push block 6, the torsion of the torsion spring 3 is weakened. Compared with the prior art, on one hand, the pushing block 6 is driven to move horizontally by the rotation of the screw rod 2, so that the torsion adjusting block 5 moves up and down, and further the torsion of the torsion spring 3 is adjusted, the friction between the pushing block 6 and other parts is small, the torsion of the torsion spring 3 is adjusted in a labor-saving manner, and certainly, the pushing block 6 is driven to rotate by the rotation of the screw rod 2, but the rotation of the pushing block 6 is blocked by the interaction of the first inclined plane and the second inclined plane; on the other hand, when the torsion of the torsion spring 3 is fixed, no other external force is needed, the torsion spring 3 gives a downward movement force to the torsion adjusting block 5, the force acts on the pushing block 6 to decompose the force, and the force comprises a component force in the vertical direction and a component force in the horizontal direction, and the component force in the horizontal direction acts on the screw rod 2 to enable the pushing block 6 and the screw rod 2 to be fixed relatively, so that the torsion of the torsion spring 3 is fixed.

In order to avoid that the screw rod 2 drives the torsion adjusting block 5 to rotate simultaneously when rotating, as shown in fig. 1, 2 and 7, a limiting block 8 is arranged below the torsion adjusting block 5, a first groove 9 for limiting the torsion adjusting block 5 up and down and accommodating the torsion adjusting block 5 is formed in the limiting block 8, and a limiting plate part 10 extends upwards from one end of the limiting block 8 far away from the torsion spring 3; a second groove 11 which is used for the sliding of the push block 6 and is matched with the bottom shape of the push block 6 is further formed in one side of the limiting block 8, which is positioned on the first groove 9. The limiting plate part 10 and the second groove 11 are matched for circumferentially limiting the push block 6 and preventing the push block from circumferentially rotating. In fact, the first inclined plane on the torque force adjusting block 5 is matched with the second inclined plane on the pushing block 6, so that the pushing block 6 can be blocked to a certain extent to rotate circumferentially, and the limiting block 8 can further limit the circumferential rotation of the pushing block 6.

As shown in fig. 1, 2 and 3, one end of the screw rod 2 is further provided with a driving mechanism for driving the screw rod 2 to rotate, the driving mechanism includes a handle 12 and at least two gears, the gears are engaged with each other, a first gear 13 is fixed on the handle 12, one end of the handle 12 close to the limiting block 8 is rotatably connected with the limiting block 8, a second gear 14 is fixed on the screw rod 2, and the first gear 13 and the second gear 14 are directly engaged with each other or indirectly engaged with each other through at least one gear. The screw rod 2 is driven to rotate through the transmission of the gear, and the operation is labor-saving. Specifically, the driving mechanism comprises a handle 12 and two gears, a first gear 13 is fixed on the handle 12, a second gear 14 is fixed on the screw rod 2, the first gear 13 and the second gear 14 are meshed with each other, and the outer diameter of the first gear 13 is larger than that of the second gear 14. The big gear wheel on the handle 12 drives the small gear wheel on the screw rod 2 to rotate, and the torsion of the torsion spring 3 can be adjusted only by rotating the handle 12 with small amplitude.

As shown in fig. 4 and 5, in the horizontal direction, the second inclined plane of the push block 6 is inclined from top to bottom along the left-to-right direction, the second inclined plane is twisted, and the right end of the push block 6 is inclined from back to front to top to bottom; in the horizontal direction, the first inclined plane of torsion regulating block 5 is followed from left to right direction and is from top to bottom inclined, and first inclined plane is the twist form, and the right-hand member of torsion regulating block 5 is followed from the backward place ahead to from top to bottom inclined.

When the swinging block 1 rotates by taking the spindle 4 as the center, the running track of one end of the swinging block 1 far away from the spindle 4 is a circular arc, that is, one end of the swing block 1 far from the spindle 4 will be displaced backwards relative to the push block 6, if the second inclined plane of the push block 6 and the first inclined plane of the torque force adjusting block 5 are planar structures, when the swinging block 1 rotates, one end of the torsion adjusting block 5 far away from the torsion spring 3 can tilt, so that the surface contact between the two is gradually changed into the contact between a line and a surface, when the swinging block is used for a long time, the inclined surfaces of the push block 6 and the torsion adjusting block 5 can be damaged, even the line contact part can be gradually developed into a plane structure, and further the resistance of rotation is increased, and the first inclined surface and the second inclined surface are arranged in a twisted shape, so that surface contact can be realized to the maximum extent, and the damage to the push block 6 and the torsion adjusting block 5 is reduced. Preferably, a third groove 15 is formed in the middle of the upper end of the torque adjusting block 5; the fourth groove 16 is formed in the middle of the lower end of the push block 6, so that the probability that the side edge of the torque force adjusting block 5 abuts against the inclined surface of the push block 6 can be reduced, and the inclined surface can be well protected.

In addition, as shown in fig. 1, two supporting columns 17 extend along the axial direction of the spindle 4 from one end of the swinging block 1 far away from the torque force adjusting block 5, the supporting columns 17 are sleeved on the spindle 4, and the outer diameter of the supporting columns 17 is smaller than or equal to the inner diameter of the torsion spring 3, so that the torsion of the torsion spring 3 when the stress is large can be avoided, and the torsion spring 3 can be protected.

In order to lock the position of the seat back frame 23, the chassis base and the second connecting base 20 may further be provided with a locking mechanism, and in one embodiment, the locking mechanism includes a plurality of locking grooves arranged in the second connecting base 20 along the up-down direction, a locking tongue arranged on the chassis base 19, a spring device arranged on the chassis base 19, and a control rope connected with the locking tongue; the seat base 19 is provided with a guide groove for accommodating the lock tongue, the spring device is arranged in the guide groove, one end of the spring device acts on the side wall of the guide groove, the other end of the spring device acts on the front part of the lock tongue to enable the lock tongue to be inserted into the locking groove backwards, a spring positioning block is arranged in the guide groove and is integrally formed or fixedly connected with the lock tongue, one end of the control rope is fixed on the spring positioning block, the other end of the control rope is arranged in the sliding groove of the seat frame 24 and moves back and forth in the sliding groove of the seat frame 24, and the control rope is driven to drive the spring positioning block to slide so as to drive the lock tongue to move in a single direction. When the chair back frame is in work, the control rope is pulled to drive the spring positioning block to slide so as to drive the spring bolt to overcome the elastic force of the spring device and move backwards to withdraw from the locking groove, the position of the chair back frame 23 can be freely adjusted, when the chair back frame is adjusted to a proper position, the control rope is loosened, and the spring bolt is reinserted into the locking groove to be locked under the elastic force action of the spring device. Thus, after the swing amplitudes of the back frame 23 and the seat frame 24 are adjusted, the back frame 23 can be locked by the lock mechanism.

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 a chair back frame (23), a chair seat frame (24), a chair base (22) and chair legs, wherein the chair back frame (23) and the chair seat frame (24) are fixedly connected or integrally formed, the chair seat frame (24) is connected with the chair legs through the chair base (22), the chair base (22) comprises a first connecting seat (18), a chassis seat (19), a second connecting seat (20), a third connecting seat (21) and a torsion adjusting mechanism, the chair legs are fixedly connected below the chassis seat (19), the chair frame is characterized in that the lower portion of the first connecting seat (18) is hinged with the front portion of the chassis seat (19), the lower portion of the second connecting seat (20) is hinged with the rear portion of the chassis seat (19), the third connecting seat (21) is positioned above the chassis seat (19) and is simultaneously and fixedly connected with the lower portion of the first connecting seat (18) and the lower portion of the second connecting seat (20), the torsion adjusting mechanism is installed in the chassis seat (19) and controls the back frame (23) and the seat frame (24) to synchronously swing, the upper part of the first connecting seat (18) is hinged with the front part of the seat frame (24), the upper part of the second connecting seat (20) is hinged with the rear part of the seat frame (24), the first connecting seat (18), the seat frame (24), the second connecting seat (20) and the chassis seat (19) form a four-link mechanism, the torsion adjusting mechanism comprises a swinging block (1), a screw rod (2) and at least one torsion spring (3), a mandrel (4) is arranged at one end of the swinging block (1) in a penetrating mode, the swinging block (1) rotates relative to the mandrel (4), the torsion spring (3) is sleeved on the mandrel (4), and the second connecting seat (20) and the chassis seat (19) are hinged through the mandrel (4); the other end of the swinging block (1) is fixedly connected or integrally formed with a torsion adjusting block (5), the upper end of the torsion adjusting block (5) is provided with a push block (6), and the screw rod (2) penetrates through the push block (6) and is in threaded connection with the push block (6); the one end movable mounting of torsional spring (3) is at the lower extreme of torsion regulating block (5) and gives torsion regulating block (5) to the trend of ejector pad (6) direction motion, and screw rod (2) rotate and drive ejector pad (6) horizontal motion, and ejector pad (6) horizontal motion impels torsion regulating block (5) to carry out the up-and-down motion, and torsion regulating block (5) and then compression or lax torsional spring (3) to adjust the amplitude of oscillation of second connecting seat (20).

2. A chair frame according to claim 1, characterized in that the upper end surface of the torsion adjusting block (5) forms a first inclined surface, and the lower end surface of the push block (6) forms a second inclined surface against the first inclined surface.

3. The chair frame according to claim 1, further comprising a limiting block (8) arranged below the torsion adjusting block (5), wherein a first groove (9) used for limiting the torsion adjusting block (5) up and down and accommodating the torsion adjusting block (5) is formed in the limiting block (8), and a limiting plate portion (10) extends upwards from one end, far away from the torsion spring (3), of the limiting block (8); a second groove (11) which is used for the sliding of the push block (6) and is matched with the shape of the bottom of the push block (6) is further formed in one side of the limiting block (8) positioned in the first groove (9).

4. A chair frame according to claim 3, characterized in that a driving mechanism for driving the screw rod (2) to rotate is arranged at one end of the screw rod (2), the driving mechanism comprises a handle (12) and at least two gears, the gears are engaged with each other, a first gear (13) is fixed on the handle (12), one end of the handle (12) close to the stopper (8) is rotatably connected with the stopper (8), a second gear (14) is fixed on the screw rod (2), and the first gear (13) and the second gear (14) are directly engaged or indirectly engaged through transmission of at least one gear.

5. The chair frame according to claim 1, wherein in the horizontal direction, the second inclined surface of the push block (6) is inclined from left to right from top to bottom, the second inclined surface is twisted, and the right end of the push block (6) is inclined from back to front from top to bottom; in the horizontal direction, the first inclined plane of torsion regulating block (5) is followed from left to right direction and is from top to bottom inclined, and first inclined plane is the distortion form, and the right-hand member of torsion regulating block (5) is followed from the back to the place ahead to from top to bottom inclined.

6. The chair frame according to claim 5, wherein a third groove (15) is formed in the middle of the upper end of the torsion adjusting block (5); and a fourth groove (16) is formed in the middle of the lower end of the push block (6).

7. The chair frame according to claim 1, wherein two supporting columns (17) extend from one end of the swinging block (1) far away from the torsion adjusting block (5) along the axial direction of the spindle (4), the supporting columns (17) are sleeved on the spindle (4), and the outer diameter of each supporting column (17) is smaller than or equal to the inner diameter of the torsion spring (3).

8. The chair frame according to claim 1, wherein an arc-shaped groove (7) is formed in a contact part of the torsion adjusting block (5) and the torsion spring (3), and one end of the torsion spring (3) is movably mounted at the lower end of the torsion adjusting block (5) and embedded in the arc-shaped groove (7).

9. A chair frame according to claim 1, characterized by comprising two torsion springs (3), wherein the two torsion springs (3) are sleeved on the spindle (4) and are respectively arranged at two opposite sides of the swinging block (1).

10. A chair frame according to claim 1, characterized in that the chair frame further comprises a chair back support frame (25), one end of the chair back support frame (25) is fixedly connected with the rear part of the second connecting seat (20), and the other end of the chair back support frame (25) is fixedly connected with the chair back frame (23).

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