CN216089783U

CN216089783U - Learning chair with adjustable backrest

Info

Publication number: CN216089783U
Application number: CN202122494679.2U
Authority: CN
Inventors: 张进义
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-10-15
Filing date: 2021-10-15
Publication date: 2022-03-22
Anticipated expiration: 2031-10-15

Abstract

The utility model discloses a learning chair with an adjustable backrest, which comprises an upright rod, a chair back, a seat board, chair legs and a lifting sleeve connected with the upright rod, wherein the chair back realizes height adjustment through the lifting sleeve; a chair back adjusting component for adjusting the sitting depth is further fixed on the lifting sleeve, and the chair back is fixedly connected with the lifting sleeve through the chair back adjusting component; the chair back adjusting assembly comprises a chair back supporting frame and a fixing frame, the chair back supporting frame is used for being connected with a chair back, the fixing frame is fixed with the lifting sleeve, and a locking piece used for adjusting the distance between the fixing frame and the chair back supporting frame is arranged on the fixing frame. The learning chair disclosed by the utility model has a backrest adjusting function, can meet the adjusting and using requirements of back fitting in the using process, adapts to the body type difference of different children and the rapid body type change of children in a long-term use period, can correct sitting postures, prevents humpback, ensures smooth blood circulation of the children, and further improves the comfort of the learning chair.

Description

Learning chair with adjustable backrest

Technical Field

The utility model relates to the field of chairs, in particular to a learning chair with an adjustable backrest.

Background

The learning chair is a unique chair designed according to various theories, can be adjusted in various ways, can be adjusted in height, sitting posture and comfort level, brings more comfortable experience to learners, and helps children to achieve the effects of humpback prevention, eye protection and high-efficiency learning to the greatest extent. But traditional study chair lacks the design consideration on the laminating degree of learner back, the study chair does not possess back regulatory function, can not satisfy the regulation user demand of back laminating in the use, long-time sitting study back can produce certain ache on the chair, especially to children's user, the back of the chair degree of depth can not be adjusted, can not let the age height all lean on to some extent at the child back that increases, can let children feel very uncomfortable, thereby rickets forward, can lead to children's vertebra to warp in the past this, the hunchback, a series of health problems such as myopia.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a learning chair which has a backrest adjusting function, can meet the adjusting and using requirements of back fitting in the using process, adapts to the body type difference of different children and the rapid body type change of the children in a long-term use, can correct sitting postures, prevent humpback, ensure blood smoothness of the children and further improve the comfort of the learning chair.

The above object of the present invention is achieved by the following technical solutions:

a learning chair with an adjustable backrest comprises an upright post, a chair back, a seat board, chair legs and a lifting sleeve connected with the upright post, wherein the chair back realizes height adjustment through the lifting sleeve;

a chair back adjusting component for adjusting the sitting depth is further fixed on the lifting sleeve, and the chair back is fixedly connected with the lifting sleeve through the chair back adjusting component;

the chair back adjusting assembly comprises a chair back supporting frame and a fixing frame, the chair back supporting frame is used for being connected with a chair back, the fixing frame is fixed with the lifting sleeve, and a locking piece used for adjusting the distance between the fixing frame and the chair back supporting frame is arranged on the fixing frame.

Through adopting above-mentioned technical scheme, the setting of lifting sleeve and back of the chair support frame for but the back of the chair adaptability height-adjusting and with the interval of pole setting, the size difference that adapts to different children and the size rapid change of children period can satisfy the regulation user demand of back laminating in the use, long-term the use can correct the position of sitting, prevents the hunchback, and guarantees that children's blood is unblocked, has further improved the travelling comfort of study chair.

The present invention in a preferred example may be further configured to: the fixing frame comprises an outer support and an inner support, the outer support is fixed with the lifting sleeve, the inner support is sleeved in the outer support, one end of the inner support, extending out of the outer support, is fixed with the chair back support frame, and a rack for adjusting the sitting depth is arranged on the outer side of the inner support; the locking piece comprises a lock pin and a shifting block for controlling the displacement of the lock pin, the bottom of the lock pin is in inserted fit with a tooth groove of the rack, and the lock pin is inserted into or far away from the rack through the shifting block;

when the lock pin is inserted into the tooth groove, the distance between the inner support and the outer support is fixed;

when the lock pin is far away from the tooth groove, the distance between the inner support and the outer support is adjustable.

By adopting the technical scheme, the length of the inner support extending out of the outer support is adjusted, the limit is realized through the lock pin, the lock pin is embedded into different tooth grooves of the rack, the limit of the length of the inner support extending out of the outer support is realized, so that the distance between the chair back and the vertical rod can be adjusted, the sitting depth is adjusted, the requirement of the chair back for being attached to the back in the using process is kept, and the comfort of the learning chair is improved.

The present invention in a preferred example may be further configured to: the inner support comprises two telescopic rods which are respectively matched with the two telescopic channels, the two telescopic rods are fixed through a fixing block, and the fixing block is fixed with the chair back support frame;

one end of the telescopic rod extending into the telescopic channel is provided with a stopping part for preventing the telescopic rod from being separated from the telescopic channel, and the tops or the bottoms of the two telescopic rods are provided with the racks.

Through adopting above-mentioned technical scheme, set up two telescopic links, can improve the steadiness that the back of the chair is connected. The two telescopic rods are fixed through the fixing blocks, so that the synchronous adjustment displacement of the two telescopic rods can be realized, and the possibility of the occurrence of the chair back deviation phenomenon is reduced.

The present invention in a preferred example may be further configured to: two the telescopic link passes through the synchronous flexible displacement of gear pole, the gear pole includes that axostylus axostyle, two fix the gear of the same model at the axostylus axostyle tip respectively, two the gear respectively with two rack toothing, the gear pole is spacing to be installed at the outer support tip and rotatable.

Through adopting above-mentioned technical scheme, the setting of gear pole has further improved the synchronism of two telescopic link displacements, reduces the telescopic link and rocks the possibility of dislocation, improves the levelness of the back of the chair left and right sides, and the back of the chair adjustment is more accurate convenient.

The present invention in a preferred example may be further configured to: an elastic piece is arranged between the telescopic rod and the telescopic channel and pushes the telescopic rod to move towards the direction far away from the telescopic channel.

Through adopting above-mentioned technical scheme, the setting up of elastic component makes the inner support automatic to the one end displacement that stretches out the outer support, then it is spacing fixed through the lock piece to need not manual pull inner support, improved the convenience of adjusting the operation.

The present invention in a preferred example may be further configured to: the elastic component comprises an adjusting spring and a spring installation pipe, one end of the spring installation pipe is closed, the other end of the spring installation pipe is opened, the spring installation pipe is fixed in the telescopic rod in a detachable mode, the end portion of the adjusting spring extends out of the opening end of the spring installation pipe and protrudes out of the telescopic rod, and one end, extending out of the telescopic rod, of the adjusting spring is abutted to the inner wall of the telescopic channel.

Through adopting above-mentioned technical scheme, the spring mounting pipe provides spacing space for the compression of adjusting spring, prevents that the skew axis of adjusting spring from buckling, and the part adjusting spring that protrudes the telescopic link is the reach of telescopic link. The spring part is simple in structure, convenient to assemble and use and convenient to maintain and replace the adjusting spring.

The present invention in a preferred example may be further configured to: the locking piece further comprises a locking plate and two sliding rods, the locking plate is fixed on the outer support, the two locking pins are respectively matched with the racks on the two telescopic rods correspondingly, the sliding rods are controlled to move along the length direction through the shifting blocks, and the sliding rods control the locking pins to be embedded into or far away from the racks;

a compression spring is fixed at one end of the lock pin, which is far away from the rack, and the lock pin is embedded into the rack under the action of the compression spring; two ends of the sliding rod in the length direction are respectively provided with an adjusting inclined surface, and the lock pin is provided with a top bracing inclined surface matched with the adjusting inclined surface;

when the high point of the adjusting inclined plane is aligned with the low point of the top bracing inclined plane, the two lock pins both displace in the direction away from the rack and are separated from the rack;

when the low point of the adjusting inclined plane is aligned with the high point of the top bracing inclined plane, the two lock pins are embedded into the tooth grooves of the rack under the action of the compression spring.

Through adopting above-mentioned technical scheme, the shifting block drives the slide bar displacement, and the lockpin at synchro control both ends inserts or keeps away from the rack, realizes that both sides are two spacing, reduces the emergence that both sides slide bar stretched out the different phenomena of displacement, and locking piece simple operation is simultaneously locked, and the practicality is strong.

The present invention in a preferred example may be further configured to: the slide bar and the shifting block are respectively arranged on the inner side and the outer side of the lock position plate, the inner side of the shifting block is fixed with the slide bar, and a displacement port for the sliding of the connecting part of the shifting block and the slide bar is formed in the lock position plate;

when the shifting block is shifted to one end of the displacement port, the two lock pins are separated from the rack;

when the shifting block is shifted to the other end of the displacement port, the two lock pins are embedded into the tooth grooves of the rack.

Through adopting above-mentioned technical scheme, the displacement mouth is injectd shifting block displacement distance, and need not to control shifting block and stir the distance, as long as it reachs the arbitrary one end in the both ends of displacement mouth, the lockpin is not inserted the tooth's socket and is kept away from the tooth's socket, the on-off state of inner support promptly to the operation is more convenient.

The present invention in a preferred example may be further configured to: the outer support is provided with an installation cavity for installing the gear rod, the opening of the installation cavity faces outwards and is sealed through a locking plate, and the locking plate is provided with a shaft rod limiting part for limiting the gear rod and a gear cavity for limiting the position of the gear.

Through adopting above-mentioned technical scheme, installation cavity, the spacing portion of axostylus axostyle, gear chamber have realized jointly that the installation to gear pole is spacing, prevent that it from taking place to jump the tooth phenomenon, and simple to operate has improved the uniformity of both sides telescopic link displacement.

The present invention in a preferred example may be further configured to: the middle part of the outer support is provided with a through hole for the vertical rod to pass through, the vertical rod passes through the through hole and is connected with the lifting sleeve, the top of the outer support is provided with a sleeve fixing position, the sleeve fixing position is fixed with a connecting block, and the outer support is fixed with the lifting sleeve through the connecting block.

Through adopting above-mentioned technical scheme, the sleeve pipe is fixed the position and the connecting block is used for connecting the lifting sleeve, and the setting of through-hole is used for improving the steadiness of being connected between back of the chair adjusting part and the pole setting, improves security and life.

In summary, the utility model includes at least one of the following beneficial technical effects:

1. the chair back is connected with the upright post through the chair back adjusting component and the lifting sleeve, the lifting sleeve is used for adjusting the height of the chair back, the chair back adjusting component is used for adjusting the distance between the chair back and the upright post to realize the seat depth adjustment, so that the chair back adjusting component can adapt to the body type difference of different children and the rapid change of the body type of the children in the period of the children, can meet the adjusting and using requirements of back attachment in the using process, can correct the sitting posture, prevent humpback after long-term use, ensure the blood smoothness of the children, and further improve the comfort of the learning chair;

2. the arrangement of the outer support, the inner support, the rack and the locking piece realizes the adjustment of the position of the chair back by adjusting the distance of the inner support extending out of the outer support and limiting the position through the locking piece, and the chair back adjusting device is simple in structure and high in practicability.

Drawings

Fig. 1 is a schematic view of the overall structure of the chair for learning of the present invention.

Fig. 2 is a self-contained schematic view of the present invention showing the connection relationship between the upright, the lifting sleeve and the backrest adjustment assembly.

Fig. 3 is an exploded view of the present invention showing the connection relationship between the upright, the lifting sleeve and the chair back adjustment assembly.

Figure 4 is a schematic exploded view of the present invention for embodying the seat back adjustment assembly.

Fig. 5 is a schematic sectional view showing the connection relationship between the external stent and the internal stent according to the present invention.

FIG. 6 is a schematic diagram of a rear structure of a latch according to the present invention.

FIG. 7 is a schematic cross-sectional view of a gear chamber embodying the present invention.

In the figure, 1, a vertical rod; 11. a lifting sleeve; 2. a chair back; 3. a seat plate; 4. chair legs; 5. a chair back support frame; 51. a groove; 52. connecting holes; 53. a cover plate; 6. a fixed mount; 61. an outer support; 611. a telescopic channel; 6111. positioning a cone; 612. installing a cavity; 613. a through hole; 614. fixing the sleeve; 615. connecting blocks; 616. a sign; 62. an inner support; 621. a telescopic rod; 6211. a rack; 6212. a stop part; 622. a fixed block; 6221. a projection; 6222. a fixing hole; 7. a locking member; 71. a lock pin; 711. a compression spring; 712. a shoring inclined plane; 72. shifting blocks; 73. a position locking plate; 731. a displacement port; 732. a shaft lever limiting part; 733. a gear cavity; 734. a chute; 74. a slide bar; 741. adjusting the inclined plane; 75. a resisting plate; 76. a lock hole; 8. a gear lever; 81. a shaft lever; 82. a gear; 9. an elastic member; 91. adjusting the spring; 92. a spring mounting tube; 10. a chair back adjustment assembly.

Detailed Description

The present invention will now be described in detail with reference to the accompanying drawings. This figure is a simplified schematic diagram, and merely illustrates the basic structure of the present invention in a schematic manner, and therefore it shows only the constitution related to the present invention.

Referring to fig. 1, the learning chair with the adjustable backrest disclosed by the utility model comprises an upright rod 1, a chair back 2, a seat plate 3, chair legs 4 and a lifting sleeve 11 connected with the upright rod 1, wherein the height of the chair back 2 is adjusted through the lifting sleeve 11. The structure of the lifting sleeve 11 is a height adjusting structure of a commercially available learning chair seat plate 3 or a chair back 2, a sleeve structure with a locking knob or a lifting sleeve 11 structure as in the content of the CN201920160763.0 patent, as long as the sleeve can be adjusted in the height direction on the upright rod 1 and can be locked.

Referring to fig. 2, a seat back adjusting assembly 10 for adjusting the seat depth is fixed on the lifting sleeve 11, and the seat back 2 is fixedly connected with the lifting sleeve 11 through the seat back adjusting assembly 10. The chair back adjusting component 10 comprises a chair back supporting frame 5 connected with the chair back 2 and a fixed frame 6 fixed with the lifting sleeve 11, and the fixed frame 6 is provided with a locking piece 7 used for adjusting the distance between the fixed frame 6 and the chair back supporting frame 5.

Referring to fig. 3 and 4, the fixing frame 6 includes an outer frame 61 and an inner frame 62, the outer frame 61 is fixed to the lifting sleeve 11, a through hole 613 for the vertical rod 1 to pass through is formed in the middle of the outer frame 61, the vertical rod 1 passes through the through hole 613 and is connected to the lifting sleeve 11, a sleeve fixing position 614 is disposed on the top of the outer frame 61, a connecting block 615 is fixed to the sleeve fixing position 614, and the outer frame 61 is fixed to the lifting sleeve 11 through the connecting block 615. One end of the outer bracket 61 facing the chair back 2 is provided with two parallel telescopic channels 611, and the two telescopic channels 611 are respectively positioned at two sides of the upright rod 1 and at the same height. Inner support 62 is sleeved in outer support 61, and inner support 62 includes two telescopic links 621 respectively with two flexible passageways 611 complex, fixes through fixed block 622 between two telescopic links 621.

The fixing block 622 is provided with one end of the telescopic rod 621 extending out of the outer bracket 61, the inner bracket 62 is approximately in an Contraband-shaped structure, one end of the fixing block 622 is integrally connected with the telescopic rod 621, the other end of the fixing block 622 is provided with a protruding part 6221 used for being connected with the chair back support frame 5, and one end face, facing the chair back support frame 5, of the protruding part 6221 is provided with a fixing hole 6222. The chair back support frame 5 is Contraband type with opening towards the chair back 2, two ends of the chair back support frame are respectively connected with the middle part of the back surface of the double-piece chair back 2, the back surface of the middle part is provided with a groove 51 for embedding the convex part 6221, and the front surface of the middle part is provided with a connecting hole 52 matched with the fixing hole 6222. During assembly, the convex part 6221 of the fixing block 622 is embedded into the groove 51, and the front connecting hole 52 of the backrest support frame 5 penetrates through a screw and is fixed with the fixing hole 6222 through a screw thread, so that the backrest support frame 5 and the inner support frame 62 are fixed. To improve the appearance, the seat back support frame 5 is snap-connected with a cover plate 53 for shielding the connection hole 52 and the screw.

Referring to fig. 5, an elastic member 9 is disposed between the telescopic rod 621 and the telescopic channel 611, and the elastic member 9 pushes the telescopic rod 621 to displace in a direction away from the telescopic channel 611. Elastic component 9 includes adjusting spring 91, spring mounting pipe 92, the one end opening is sealed to spring mounting pipe 92 one end, spring mounting pipe 92 detachable coaxial fixation is in telescopic link 621, adjusting spring 91 tip stretches out spring mounting pipe 92's open end and protrusion telescopic link 621, adjusting spring 91 stretches out telescopic link 621's one end and contradicts with flexible passageway 611 inner wall, flexible passageway 611 inner wall is equipped with the location awl 6111 that is used for injecing adjusting spring 91 end position, adjusting spring 91 cup joints on location awl 6111.

Referring to fig. 4 and 5, one end of the telescopic bars 621 extending into the telescopic channel 611 is provided with a stop portion 6212 for preventing the telescopic bars 621 from being separated from the telescopic channel 611, and the tops or bottoms of the two telescopic bars 621 are provided with racks 6211, and the racks 6211 are used for cooperating with the locking members 7. The two telescopic rods 621 are synchronously telescopic and displaceable through the gear 82 and the rod 8, the gear 82 and the rod 8 comprise a shaft 81 and two gears 82 of the same type which are respectively fixed at the end part of the shaft 81, the two gears 82 are respectively kept in a meshing relationship with the two racks 6211, and the gear 82 and the rod 8 are limited and installed at the end part of the outer bracket 61 and can rotate. Preferably, the rack 6211 is disposed at the top of the retractable bar 621, the stop portion 6212 is disposed at the end of the rack 6211, and the stop portion 6212 is a convex section with a width larger than the pitch of the rack 6211, so that the limit gear 82 cannot pass through the end of the rack 6211 completely.

Referring to fig. 3 and 4, the locking member 7 includes a lock position plate 73, a slide rod 74, two lock pins 71 longitudinally slidably disposed at the bottoms of the two ends of the lock position plate 73, and a dial 72 for controlling the displacement of the lock pins 71. The bottom of the two ends of the locking plate in the length direction is provided with a sliding groove 734 for the locking pin 71 to be embedded and slide, the top of the locking pin 71 is fixed with a compression spring 711, the compression spring 711 is positioned between the top of the locking pin 71 and the top of the sliding groove 734, under the action of the compression spring 711, when the spring is in an unstressed state, the locking pin 71 extends out of the sliding groove 734 and can be embedded into a tooth groove of the rack 6211, and when the compression spring 711 is stressed and compressed, the locking pin 71 can retract into the sliding groove 734 and is separated from the rack 6211.

Referring to fig. 5 and 6, the locking plate 73 is fixed to an end surface of the outer bracket 61 facing the seat back support frame 5 by bolts, two lock pins 71 are respectively matched with the racks 6211 on the two telescopic rods 621, the sliding rod 74 is controlled by the shifting block 72 to move along the length direction, and the sliding rod 74 controls the lock pins 71 to be embedded in or away from the racks 6211. When the locking pin 71 is inserted into the tooth groove, the distance between the inner support 62 and the outer support 61 is fixed; when the locking pin 71 is far away from the tooth socket, the distance between the inner support 62 and the outer support 61 is adjustable. Two ends of the sliding rod 74 in the length direction are respectively provided with an adjusting inclined plane 741, and the lock pin 71 is provided with a top support inclined plane 712 matched with the adjusting inclined plane 741. The sliding rod 74 and the shifting block 72 are respectively arranged at the inner side and the outer side of the locking plate 73, and a displacement port 731 for the sliding of the connecting part of the shifting block 72 and the sliding rod 74 is arranged on the locking plate 73. The inner side of the shifting block 72 is fixed with a slide rod 74 through screws, the inner side of the slide rod 74 is provided with a resisting plate 75, the resisting plate 75 and the slide rod 74 are provided with lock holes 76, the inner side of the shifting block 72 is provided with screw fixing holes 6222, the screws sequentially penetrate through the lock holes 76 and the displacement holes 731 of the resisting plate and the slide rod 74 and then are fixed with the screw fixing holes 6222 through threads, and therefore the slide rod 74 is fixedly connected with the shifting block 72.

When the shifting block 72 is shifted to one end of the displacement opening 731, the high point of the adjusting inclined plane 741 is aligned with the low point of the top supporting inclined plane 712, and the two lock pins 71 both displace in the direction away from the rack 6211 and are separated from the rack 6211. When the shifting block 72 is shifted to the other end of the displacement opening 731, the low point of the adjusting inclined plane 741 is aligned with the high point of the top supporting inclined plane 712, and the two lock pins 71 are embedded into the tooth grooves of the rack 6211 under the action of the compression spring 711. In order to make the user know whether the telescopic rod 621 is in the locking state or the telescopic state more intuitively, a sign 616 may be disposed above the locking plate, the sign 616 may be fixed on the outer bracket 61, and the sign 616 indicates, by an arrow and a character, that both ends of the displacement port 731 are in the telescopic state and the locking state, respectively.

Referring to fig. 6 and 7, in order to facilitate the installation and position limitation of the gear 82 and the lever 8, the outer bracket 61 is provided with an installation cavity 612 for installing the gear lever 8, the installation cavity 612 has an opening facing outward and is closed by the capture plate 73 of the locking member 7, and the capture plate 73 is provided with a shaft 81 limiting part 732 for limiting the gear lever 8 and a gear cavity 733 for limiting the position of the gear 82.

The implementation principle of the utility model is as follows: the shifting block 72 is shifted to drive the sliding rod 74 to move to the end of the displacement port 731 in the telescopic direction, at this time, the high point of the adjusting inclined plane 741 is aligned with the low point of the top supporting inclined plane 712, the two lock pins 71 both move in the direction away from the rack 6211 and are separated from the rack 6211, the telescopic rod 621 moves in the direction extending out of the outer bracket 61 under the action of the adjusting spring 91, and meanwhile, the gears 82 on the two sides of the gear rod 8 synchronously rotate to prevent the telescopic displacement difference of the telescopic rods 621 on the two sides. When the telescopic rod 621 moves to a proper length, the shifting block 72 is shifted to the locking end of the displacement opening 731, the low point of the adjusting inclined plane 741 is aligned with the high point of the top supporting inclined plane 712, the two lock pins 71 are embedded into the tooth grooves of the rack 6211 under the action of the compression spring 711, the telescopic rod 621 does not move any more, the distance between the chair back 2 and the vertical rod 1 is fixed, and the adjustment of the sitting depth is completed.

According to the learning chair, the chair back 2 is connected with the upright stanchion 1 through the chair back adjusting component 10 and the lifting sleeve 11, the lifting sleeve 11 is used for adjusting the height of the chair back 2, the chair back adjusting component 10 is used for adjusting the distance between the chair back 2 and the upright stanchion 1, and the sitting depth adjustment is realized, so that the chair can adapt to the body type difference of different children and the rapid change of the body type of the children in the period, can meet the adjusting and using requirements of back fitting in the using process, can correct sitting postures after long-term use, prevent humpback, ensure the blood smoothness of the children, and further improve the comfort of the learning chair.

The arrangement of the outer support 61, the inner support 62, the rack 6211 and the locking piece 7 realizes the adjustment of the position of the chair back 2 by adjusting the distance that the inner support 62 extends out of the outer support 61 and limiting the position by the locking piece 7, and has simple structure and strong practicability.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the utility model are covered by the protection scope of the utility model.

Claims

1. A learning chair with an adjustable backrest comprises a vertical rod (1), a chair back (2), a seat plate (3), chair legs (4) and a lifting sleeve (11) connected with the vertical rod (1), wherein the chair back (2) is adjusted in height through the lifting sleeve (11);

the method is characterized in that: a chair back adjusting component (10) for adjusting the sitting depth is further fixed on the lifting sleeve (11), and the chair back (2) is fixedly connected with the lifting sleeve (11) through the chair back adjusting component (10);

the chair back adjusting assembly (10) comprises a chair back supporting frame (5) connected with the chair back (2) and a fixing frame (6) fixed with a lifting sleeve (11), and a locking piece (7) used for adjusting the distance between the fixing frame (6) and the chair back supporting frame (5) is arranged on the fixing frame (6).

2. The chair as claimed in claim 1, wherein: the fixing frame (6) comprises an outer support (61) and an inner support (62), the outer support (61) is fixed with the lifting sleeve (11), the inner support (62) is sleeved in the outer support (61), one end of the inner support (62) extending out of the outer support (61) is fixed with the chair back support frame (5), and a rack (6211) for adjusting the seating depth is arranged on the outer side of the inner support (62); the locking piece (7) comprises a locking pin (71) and a shifting block (72) for controlling the displacement of the locking pin (71), the bottom of the locking pin (71) is in inserted fit with the tooth groove of the rack (6211), and the locking pin (71) is inserted into or separated from the rack (6211) through the shifting block (72);

when the lock pin (71) is inserted into the tooth groove, the distance between the inner support (62) and the outer support (61) is fixed;

when the lock pin (71) is far away from the tooth groove, the distance between the inner support (62) and the outer support (61) is adjustable.

3. The chair of claim 2, wherein: one end, facing the chair back (2), of the outer support (61) is provided with two parallel telescopic channels (611), the inner support (62) comprises two telescopic rods (621) which are respectively matched with the two telescopic channels (611), the two telescopic rods (621) are fixed through a fixing block (622), and the fixing block (622) is fixed with the chair back support frame (5);

one end of the telescopic rod (621) extending into the telescopic channel (611) is provided with a stop part (6212) for preventing the telescopic rod (621) from being separated from the telescopic channel (611), and the tops or bottoms of the two telescopic rods (621) are provided with the racks (6211).

4. The chair of claim 3, wherein: two telescopic link (621) are through gear lever (8) synchronous flexible displacement, gear lever (8) include axostylus axostyle (81), two fix respectively in the gear (82) of the same model of axostylus axostyle (81) tip, two gear (82) mesh with two rack (6211) respectively, gear lever (8) are by spacing installation in outer support (61) tip and rotatable.

5. The chair of claim 4, wherein: an elastic piece (9) is arranged between the telescopic rod (621) and the telescopic channel (611), and the elastic piece (9) pushes the telescopic rod (621) to displace in the direction away from the telescopic channel (611).

6. The chair of claim 5, wherein: elastic component (9) are including adjusting spring (91), spring mounting pipe (92) one end closed end opening, spring mounting pipe (92) detachable is coaxial to be fixed in telescopic link (621), adjusting spring (91) tip stretches out the open end of spring mounting pipe (92) and projects telescopic link (621), adjusting spring (91) stretch out the one end of telescopic link (621) and contradict with flexible passageway (611) inner wall.

7. The chair as claimed in any one of claims 4 to 6, wherein: the locking piece (7) further comprises a locking plate (73) and a sliding rod (74), the locking plate (73) is fixed on the outer support (61), the number of the locking pins (71) is two, the two locking pins (71) are respectively matched with the racks (6211) on the two telescopic rods (621) correspondingly, the sliding rod (74) is controlled to move along the length direction through a shifting block (72), and the sliding rod (74) controls the locking pins (71) to be embedded into or far away from the racks (6211);

a compression spring (711) is fixed at one end of the lock pin (71) which is far away from the rack (6211), and the lock pin (71) is embedded into the rack (6211) under the action of the compression spring (711); two ends of the sliding rod (74) in the length direction are respectively provided with an adjusting inclined plane (741), and the lock pin (71) is provided with a top bracing inclined plane (712) matched with the adjusting inclined plane (741);

when the high point of the adjusting inclined plane (741) is aligned with the low point of the top supporting inclined plane (712), the two lock pins (71) are displaced in the direction away from the rack (6211) and separated from the rack (6211);

when the low point of the adjusting inclined plane (741) is aligned with the high point of the top bracing inclined plane (712), the two lock pins (71) are embedded into the tooth grooves of the rack (6211) under the action of the compression spring (711).

8. The chair of claim 7, wherein: the sliding rod (74) and the shifting block (72) are respectively arranged on the inner side and the outer side of the lock position plate (73), the inner side of the shifting block (72) is fixed with the sliding rod (74), and a displacement opening (731) for the sliding of the connecting part of the shifting block (72) and the sliding rod (74) is formed in the lock position plate (73);

when the shifting block (72) is shifted to one end of the displacement port (731), the two lock pins (71) are separated from the rack (6211);

when the shifting block (72) is shifted to the other end of the displacement opening (731), the two lock pins (71) are embedded into the tooth grooves of the rack (6211).

9. The chair of claim 7, wherein: the gear rack is characterized in that an installation cavity (612) for installing the gear rod (8) is formed in the outer support (61), an opening of the installation cavity (612) faces outwards and is sealed through a locking plate (73), and a shaft rod (81) limiting part (732) for limiting the gear rod (8) and a gear cavity (733) for limiting the position of the gear (82) are arranged on the locking plate (73).

10. The chair as claimed in any one of claims 2 to 6, wherein: the middle of the outer support (61) is provided with a through hole (613) for the vertical rod (1) to pass through, the vertical rod (1) passes through the through hole (613) and is connected with the lifting sleeve (11), the top of the outer support (61) is provided with a sleeve fixing position (614), the sleeve fixing position (614) is fixed with a connecting block (615), and the outer support (61) is fixed with the lifting sleeve (11) through the connecting block (615).