Chair leg telescopic device and chair leg assembly

Abstract

The utility model discloses a chair leg telescopic device and a chair leg assembly, the chair leg telescopic device comprises a sliding pipe, a supporting pipe, a lead screw and an adjusting piece, the sliding pipe and the supporting pipe are both of hollow tubular structures, the supporting pipe is connected to the supporting pipe in a sleeving mode, and the top end of the sliding pipe is configured to support a chair seat; the screw rod is arranged in the supporting pipe and comprises a screw rod and a turning gear box at the bottom of the screw rod, a guide sleeve is embedded in the bottom of the sliding pipe, an inner threaded hole is formed in the guide sleeve in the length direction in a hollowed-out mode, and the screw rod is in threaded connection with the guide sleeve through the inner threaded hole, so that when the screw rod rotates in the horizontal direction, the screw rod forces the guide sleeve to slide up and down along the screw rod; the sliding pipe is driven to slide up and down along the supporting pipe; a connecting hole is formed in the portion, right opposite to the direction-changing gearbox, of the side wall of the supporting pipe in a hollowed-out mode, the adjusting piece penetrates through the connecting hole and is rotationally connected to the direction-changing gearbox, and the direction-changing gearbox is configured to convert rotation of the adjusting piece in the vertical direction into rotation of the screw in the horizontal direction, so that the sliding pipe is adjusted to slide up and down along the supporting pipe.

Description

Technical Field

[0001] The utility model generally relates to the technical field of seats, and particularly relates to a chair leg telescopic device and a chair leg assembly. Background Art

[0002] The spinal health of children has always been a concern for parents. When children study at their desks with poor sitting postures for a long time, it is easy to cause health problems such as myopia, hunchback, and scoliosis. Therefore, parents usually choose children's chairs with seat heights and depths suitable for their children's body types to assist children in correcting their sitting postures and protecting spinal health. However, due to the rapid growth of children's body types, if the seat height of the children's chair is fixed, parents need to frequently replace the chairs during the growth process of their children, resulting in too high expenses.

[0003] To solve the above problems, a seat with adjustable seat height has emerged in the existing market. For example, a children's study chair provided by an existing patent (Application No.: CN201620720529.5), a vertical rod is vertically arranged on the chair support base, the rear side of the seat board is sleeved on the vertical rod through a seat board lifting sleeve and can slide up and down along the vertical rod, and several holes are vertically formed on the vertical rod, and a locking knob is correspondingly arranged on the seat board lifting sleeve. When the height of the seat board is adjusted to a suitable position, the locking knob is inserted into the corresponding hole to fix the height position of the seat board. The adjustment structure is simple and the support effect is relatively reliable.

[0004] However, the above scheme has the following problems: Since the vertical rod and the seat board lifting sleeve are located at the rear of the seat, when the user adjusts the seat height, he needs to get up from the seat, then control the seat board to adjust the height with one hand and control the locking knob to lock with the other hand. This not only makes the seat height adjustment operation more cumbersome, but also difficult for children with relatively small strength to perform the adjustment operation independently; moreover, the seat board lifting sleeve can only be fixed at the position where the hole is formed on the vertical rod, that is, the seat height adjustment of the above children's study chair belongs to stepped adjustment, and the adjustment freedom is relatively low, and the practicability is poor. Summary of the Invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a chair leg telescopic device and a chair leg assembly. When the seat height needs to be adjusted, the user does not need to get up from the seat, but only needs to bend down and rotate the adjusting member to drive the screw rod to rotate and drive the sliding tube to move up and down, so as to adjust the seat height of the chair, making the seat height adjustment operation very simple and labor-saving, and even children can independently perform the adjustment; moreover, the adjustment of the sliding tube by screw rod transmission belongs to stepless adjustment, that is, the sliding tube can stay at any height, thereby increasing the adjustment freedom of the seat height and having better practicability.

[0006] The effect of the utility model is achieved as follows:

[0007] In a first aspect, the present application provides a chair leg telescopic device, which includes a sliding tube, a support tube, a lead screw, and an adjusting member. Both the sliding tube and the support tube are hollow tubular structures, and the support tube is sleeved on the support tube, such that the sliding tube can slide up and down relative to the support tube. The top end of the sliding tube is configured to support the seat. The lead screw is disposed inside the support tube, and the lead screw includes a screw rod and a direction-changing gearbox at the bottom of the screw rod. A guide sleeve is embedded at the bottom of the sliding tube, and the guide sleeve is provided with an internal threaded hole that is hollowed out along the length direction. The screw rod is screwed to the guide sleeve through the internal threaded hole, such that when the screw rod rotates horizontally, the screw rod forces the guide sleeve to slide up and down along the screw rod, thereby driving the sliding tube to slide up and down along the support tube. A connection hole is hollowed out at a position on the side wall of the support tube opposite to the direction-changing gearbox, and the adjusting member passes through the connection hole and is rotatably connected to the direction-changing gearbox. The direction-changing gearbox is configured to convert the rotation of the adjusting member in the vertical direction into the rotation of the screw rod in the horizontal direction, thereby adjusting the sliding tube to slide up and down along the support tube and further adjusting the height of the seat.

[0008] Further, the guide sleeve is a split structure, including a first sleeve body and a second sleeve body that are spliced left and right, and the internal threaded hole is formed by splicing the recessed parts of the first sleeve body and the second sleeve body. This makes the assembly operation of the chair leg telescopic device relatively simple.

[0009] Further, the adjusting member includes an adjusting rod that is rotatably engaged with the direction-changing gearbox, and a handwheel is provided at one end of the adjusting rod away from the direction-changing gearbox. The handwheel is configured for the user to operate the adjusting member. The user only needs to rotate the handwheel to drive the adjusting rod to rotate, and then drive the sliding tube to slide up and down under the transmission of the lead screw, and the adjustment operation is relatively simple.

[0010] Further, the adjusting member includes an adjusting rod that is rotatably engaged with the direction-changing gearbox, and a crank is provided at one end of the adjusting rod away from the direction-changing gearbox. The other end of the crank protrudes towards the direction away from the direction-changing gearbox and is provided with a handle. When the handle drives the crank to make a circular motion, the adjusting rod is driven by the crank to rotate. The user only needs to rotate the handle to drive the adjusting rod to rotate, and then drive the sliding tube to slide up and down under the transmission of the lead screw, and the adjustment operation is relatively simple.

[0011] Further, the sliding tube and the support tube are inclined backward and upward, and a secondary support leg that is inclined forward and upward is provided at the rear side of the support tube. The upper end of the secondary support leg supports on the sliding tube, and the lower end of the secondary support leg and the lower end of the support tube jointly support on the ground. This increases the overall support surface of the chair leg telescopic device, ensuring that the center of gravity of the entire seat can fall within the support surface after being installed on the seat, and the stability is relatively good.

[0012] Further, a roller is rotatably connected to the bottom end of the secondary support leg, and the roller rolls in the front-rear direction and drives the chair leg telescopic device to move in the front-rear direction. This makes the movement operation of the seat very labor-saving. [[ID=

[17] ]]

[0013] Furthermore, the sliding tube and the support tube are vertically arranged, and a horizontally arranged auxiliary support leg is connected to the bottom end of the support tube. The auxiliary support leg is configured to support on the ground. This makes the overall structure of the chair leg telescopic assembly in an inverted T shape, increasing the overall support area of the chair leg telescopic device, ensuring that after being installed on the seat, the center of gravity of the entire seat can fall within the support area, and the stability is relatively good.

[0014] In a second aspect, the present application also provides a chair leg assembly, which includes two sets of chair leg telescopic devices that are symmetric left and right. A transmission shaft is connected between the two support tubes, and the two ends of the transmission shaft are respectively connected to the left and right steering gearboxes. When adjusting the adjusting member on one side is rotated, the two steering gearboxes on both sides operate synchronously through the transmission of the transmission shaft. Furthermore, the sliding tubes on both sides can slide up and down synchronously under the transmission of the screw rod, thereby adjusting the overall height of the chair leg assembly. This enables the user to only rotate the adjusting member on one side to synchronously adjust the sliding tubes on both sides to slide up and down, further improving the simplicity of the seat height adjustment operation.

[0015] Furthermore, a tubular protective sleeve is horizontally arranged between the support tubes on both sides, and the transmission shaft is arranged inside the protective sleeve. The protective sleeve not only protects the transmission shaft, but also can be used as a footrest for the chair leg assembly, improving the practicality.

[0016] Furthermore, a stop member is detachably arranged on the transmission shaft, and the stop member abuts against the outer wall of one of the support tubes, preventing the transmission shaft from sliding left and right relative to the support tube, improving the stability of the chair leg assembly, and avoiding the transmission shaft disengaging from the support tube during rotation, resulting in the inability to synchronously adjust the chair leg telescopic devices on both sides.

[0017] For the chair leg telescopic device and chair leg assembly provided by the present application, the sliding tube and the support tube are connected by a lead screw. When the seat height needs to be adjusted, the user does not need to get up from the seat. Only by bending down and rotating the adjusting member can the screw rod be driven to rotate and drive the sliding tube to move up and down, thereby adjusting the seat height. This makes the seat height adjustment operation very simple and labor-saving. Even a child can independently perform the adjustment. Moreover, adjusting the sliding tube through the lead screw drive is stepless adjustment, that is, the sliding tube can stay at any height, thereby increasing the freedom of seat height adjustment and having better practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, purposes, and advantages of the present application will become more obvious:

[0019] Figure 1 It is a three-dimensional structure diagram of the chair leg assembly provided by the embodiment of the present application;

[0020] Figure 2 It is a three-dimensional structure diagram of the chair leg assembly when the seat height is adjusted to the highest provided by the embodiment of the present application;

[0021] Figure 3 Schematic cross-sectional structure diagram of the chair leg assembly provided by the embodiment of the present application;

[0022] Figure 4 Schematic cross-sectional structure diagram of the chair leg assembly when the seat height is adjusted to the highest provided by the embodiment of the present application;

[0023] Figure 5 Schematic connection structure diagram between the sliding tube and the support tube provided by the embodiment of the present application;

[0024] Figure 6 Schematic connection structure diagram between the lead screw and the sliding tube provided by the embodiment of the present application;

[0025] Figure 7 Schematic connection structure diagram between the transmission shaft and the chair leg telescopic device provided by the embodiment of the present application;

[0026] Figure 8 Schematic back structure diagram of the chair leg assembly provided by the embodiment of the present application;

[0027] Figure 9 Schematic three-dimensional structure diagram of the chair leg telescopic device when the adjusting member is a crank structure provided by the embodiment of the present application;

[0028] Figure 10 Schematic side structure diagram of the chair leg telescopic device when it is an inverted T-shaped structure provided by the embodiment of the present application.

[0029] Each reference numeral is: 1 - sliding tube, 110 - guide sleeve, 111 - internal thread hole, 110a - first sleeve body, 110b - second sleeve body, 120 - chair seat support frame, 2 - support tube, 201 - connection hole, 210 - auxiliary support leg, 211 - pulley, 220 - protective sleeve, 221 - connection part, 222 - avoidance opening, 3 - lead screw, 310 - screw rod, 320 - direction-changing gearbox, 330 - transmission shaft, 331 - stop member, 4 - adjusting member, 410 - adjusting rod, 420 - hand wheel, 430 - crank, 431 - handle. Detailed implementation manners

[0030] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant utility model, rather than limiting the utility model. Additionally, it should be noted that for the sake of description, only the parts related to the utility model are shown in the drawings.

[0031] Please refer to the attached Figures 1-10, an embodiment of the present application provides a leg telescopic device for a chair, which includes a sliding tube 1, a support tube 2, a lead screw 3, and an adjusting member 4. Both the sliding tube 1 and the support tube 2 are hollow tubular structures, and the support tube 2 is sleeved on the support tube 2, so that the sliding tube 1 can slide up and down relative to the support tube 2. The top end of the sliding tube 1 is configured to support the chair seat. The lead screw 3 is arranged inside the support tube 2. The lead screw 3 includes a screw rod 310 and a direction-changing gearbox 320 at the bottom of the screw rod 310. A guide sleeve 110 is embedded at the bottom of the sliding tube 1. The guide sleeve 110 is provided with an internal threaded hole 111 that is hollowed out along the length direction. The screw rod 310 is screwed to the guide sleeve 110 through the internal threaded hole 111. When the screw rod 310 rotates horizontally, the screw rod 310 forces the guide sleeve 110 to slide up and down along the screw rod 310, thereby driving the sliding tube 1 to slide up and down along the support tube 2. A connection hole 201 is hollowed out at a position on the side wall of the support tube 2 opposite to the direction-changing gearbox 320. The adjusting member 4 passes through the connection hole 201 and is rotatably connected to the direction-changing gearbox 320. The direction-changing gearbox 320 is configured to convert the rotation of the adjusting member 4 in the vertical direction into the rotation of the screw rod 310 in the horizontal direction, so as to adjust the sliding tube 1 to slide up and down along the support tube 2 and further adjust the height of the chair seat.

[0032] In this embodiment, the sliding tube 1 and the support tube 2 are connected by a lead screw 3. When the seat height needs to be adjusted, the user does not need to get up from the seat. Only by bending down and rotating the adjusting member 4 can the screw rod 310 be driven to rotate and drive the sliding tube 1 to move up and down, so as to adjust the height of the chair seat. The seat height adjustment operation is very simple and labor-saving. Even a child can independently adjust it. Moreover, the adjustment of the sliding tube 1 by driving through the lead screw 3 is stepless adjustment, that is, the sliding tube 1 can stay at any height, thereby improving the freedom of seat height adjustment and having better practicability.

[0033] Among them, the top end of the sliding tube 1 extends horizontally to form a bent chair seat support frame 120, and the chair seat support frame 120 is configured to connect and support the bottom of the chair seat.

[0034] Please refer to the attached Figure 6 , in some embodiments of the present application, the guide sleeve 110 is a split structure, including a first sleeve body 110a and a second sleeve body 110b that are spliced left and right. The internal threaded hole 111 is formed by splicing the recessed parts of the first sleeve body 110a and the second sleeve body 110b.

[0035] In this embodiment, by setting the guide sleeve 110 as a split structure, when installing the chair leg telescopic device, the lead screw 3 can be first installed in the support tube 2, and then the first sleeve body 110a and the second sleeve body 110b are assembled and installed on the screw 310, so as to install the guide sleeve 110 on the screw 310. Finally, the sliding tube 1 is sleeved on the screw 310, and the guide sleeve 110 is embedded in the lower side of the sliding tube 1, thus completing the assembly operation of the chair leg telescopic device, making the assembly operation relatively simple and convenient.

[0036] Please refer to the attached Figure 5 , in some embodiments of the present application, the adjusting member 4 includes an adjusting rod 410 rotatably engaged with the steering gearbox 320. A handwheel 420 is provided at one end of the adjusting rod 410 away from the steering gearbox 320, and the handwheel 420 is configured for the user to operate the adjusting member 4. The user only needs to rotate the handwheel 420 to drive the rotation of the adjusting rod 410, and then drive the sliding tube 1 to slide up and down under the drive of the lead screw 3, and the adjustment operation is relatively simple and convenient.

[0037] Among them, preferably, the cross-section of the shaft hole of the steering gearbox 320 is a hexagonal structure, and the adjusting rod 410 is a corresponding hexagonal shaft structure.

[0038] Please refer to the attached Figure 9 , in some embodiments of the present application, the adjusting member 4 can also be other structures: the adjusting member 4 includes an adjusting rod 410 rotatably engaged with the steering gearbox 320. A crank 430 is provided at one end of the adjusting rod 410 away from the steering gearbox 320, and a handle 431 protrudes from the other end of the crank 430 in a direction away from the steering gearbox 320. When the handle 431 drives the crank 310 to make a circular motion, the adjusting rod 410 is driven by the crank 430 to rotate itself. The user only needs to rotate the handle 431 to drive the rotation of the adjusting rod 410, and then drive the sliding tube 1 to slide up and down under the drive of the lead screw 3, and the adjustment operation is relatively simple and convenient.

[0039] Please refer to the attached Figures 1-2 , in some embodiments of the present application, the sliding tube 1 and the support tube 2 are inclined backward and upward. A secondary support leg 210 inclined forward and upward is provided at the rear side of the support tube 2. The upper end of the secondary support leg 210 supports on the sliding tube 1, and the lower end of the secondary support leg 210 and the lower end of the support tube 2 jointly support on the ground.

[0040] In this embodiment, by inclining the sliding tube 1 and the support tube 2 and providing the inclined secondary support leg 210 to connect the support tube 2, the overall support surface of the chair leg telescopic device is increased, ensuring that after being installed on the seat, the overall center of gravity of the seat can fall within the support surface, and the stability is relatively good.

[0041] Please refer to the attached Figure 8, in some embodiments of the present application, a roller 211 is rotatably connected to the bottom end of the auxiliary support leg 210. The roller 211 rolls in the front-rear direction and drives the chair leg telescopic device to move in the front-rear direction. When the user needs to move the seat, only need to tilt the seat backward as a whole, so that the bottom end of the support tube 2 is suspended. The whole seat is supported on the ground by the roller 211, and the seat is moved by the rolling of the roller 211, so that the movement operation of the seat is very labor-saving.

[0042] Please refer to the appendix Figure 10 , in some embodiments of the present application, the chair leg telescopic assembly may also have other structures: the sliding tube 1 and the support tube 2 are vertically arranged, and a horizontally arranged auxiliary support leg 210 is connected to the bottom end of the support tube 2. The auxiliary support leg 210 is configured to support on the ground. So that the whole chair leg telescopic assembly has an inverted T-shaped structure. Supported on the ground by the auxiliary support leg 210 with a larger horizontal width, the support surface of the whole chair leg telescopic device is increased, ensuring that after being installed on the seat, the center of gravity of the whole seat can fall within the support surface, and the stability is good.

[0043] Please refer to the appendix Figures 1-7 , the embodiments of the present application also provide a chair leg assembly, including two groups of chair leg telescopic devices that are symmetric left and right. A transmission shaft 330 is connected between the two support tubes 2. The two ends of the transmission shaft 330 are respectively connected to the left and right variable direction gear boxes 320. When the adjusting member 4 on one side is rotated, the left and right variable direction gear boxes 320 operate synchronously through the transmission of the transmission shaft 330. Furthermore, the sliding tubes 1 on both sides can slide up and down synchronously under the transmission of the screw 310, so as to adjust the overall height of the chair leg assembly.

[0044] In this embodiment, the left and right variable direction gear boxes 320 are linked through the transmission shaft 330, so that the user only needs to rotate the adjusting member 4 on one side to synchronously adjust the up and down sliding of the sliding tubes 1 on both sides, thereby adjusting the overall height of the chair leg assembly, and further improving the simplicity of the seat height adjustment operation.

[0045] Among them, preferably, the adjusting member 4 is only connected to the support tube 2 on one side, so that the chair leg assembly is more lightweight in appearance and improves the aesthetics.

[0046] Among them, the structure of the transmission shaft 330 corresponds to the shape of the shaft hole of the variable direction gear box 320, and it is a hexagonal shaft structure.

[0047] Please refer to the appendix Figures 7-8 , in some embodiments of the present application, a tubular protective sleeve 220 is horizontally arranged between the two support tubes 2, and the transmission shaft 330 is arranged inside the protective sleeve 220.

[0048] In this embodiment, by arranging the protective sleeve 220 to be sleeved outside the transmission shaft 330, it not only plays a protective role for the transmission shaft 330, but also the protective sleeve 220 can be used as a footrest of the chair leg assembly, improving the practicability.

[0049] Preferably, both left and right ends of the protective sleeve 220 extend in the vertical direction to form connecting parts 221, and the connecting parts 221 are detachably connected to the support tube 2 by means of screw connection, making the installation and disassembly operations of the protective sleeve 220 more convenient.

[0050] Please refer to the attached Figures 7-8 , in some embodiments of the present application, a stop member 331 is detachably arranged on the transmission shaft 330, and the stop member 331 abuts against the outer wall of the support tube 3 on one side, so that the transmission shaft 330 cannot slide left and right relative to the support tube 3, improving the stability of the chair leg assembly and preventing the transmission shaft 330 from detaching from the support tube 2 during rotation, resulting in the inability to synchronously adjust the chair leg telescopic devices on both sides.

[0051] Preferably, please refer to the attached Figure 8 , the stop member 331 is a screw, making the installation and disassembly operations of the stop member 331 relatively simple. Moreover, avoidance openings 222 are formed on both left and right sides at the rear end of the protective sleeve 220, so that the stop member 331 can be screwed into the transmission shaft 330 from the avoidance openings 222, further improving the simplicity of the installation and disassembly operations of the stop member 331.

[0052] It should be understood that terms such as "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicating orientation or positional relationship above are based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is more than three.

[0053] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the utility model involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept of the utility model. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) disclosed in the present application that have similar functions.

Claims

1. A chair leg telescopic device, characterized in that, It includes a sliding tube (1), a support tube (2), a lead screw (3) and an adjusting member (4). The sliding tube (1) and the support tube (2) are both hollow tubular structures, and the support tube (2) is sleeved on the support tube (2) so that the sliding tube (1) can slide up and down relative to the support tube (2). The top end of the sliding tube (1) is configured to support a seat. The lead screw (3) is arranged inside the support tube (2). The lead screw (3) includes a screw rod (310) and a direction-changing gearbox (320) at the bottom of the screw rod (310). A guide sleeve (110) is embedded at the bottom of the sliding tube (1). The guide sleeve (110) is provided with an internal threaded hole (111) hollowed out along the length direction. The screw rod (310) is screwed to the guide sleeve (110) through the internal threaded hole (111). When the screw rod (310) rotates horizontally, the screw rod (310) forces the guide sleeve (110) to slide up and down along the screw rod (310), thereby driving the sliding tube (1) to slide up and down along the support tube (2). A connection hole (201) is hollowed out at a position on the side wall of the support tube (2) opposite to the direction-changing gearbox (320). The adjusting member (4) passes through the connection hole (201) and is rotatably connected to the direction-changing gearbox (320). The direction-changing gearbox (320) is configured to convert the rotation of the adjusting member (4) in the vertical direction into the rotation of the screw rod (310) in the horizontal direction, so as to adjust the up and down sliding of the sliding tube (1) along the support tube (2) and further adjust the height of the seat.

2. The chair leg telescopic device according to claim 1, characterized in that, The guide sleeve (110) is a split structure, including a first sleeve body (110a) and a second sleeve body (110b) spliced left and right. The internal threaded hole (111) is formed by splicing the recessed parts of the first sleeve body (110a) and the second sleeve body (110b).

3. The chair leg telescopic device according to claim 1, characterized in that, The adjusting member (4) includes an adjusting rod (410) rotatably matched with the direction-changing gearbox (320). A handwheel (420) is arranged at one end of the adjusting rod (410) away from the direction-changing gearbox (320). The handwheel (420) is configured for the user to operate the adjusting member (4).

4. The chair leg telescopic device according to claim 1, characterized in that, The adjusting member (4) includes an adjusting rod (410) rotatably matched with the direction-changing gearbox (320). A crank (430) is arranged at one end of the adjusting rod (410) away from the direction-changing gearbox (320). The other end of the crank (430) protrudes towards the direction away from the direction-changing gearbox (320) and is provided with a handle (431). When the handle (431) drives the crank (310) to make a circular motion, the adjusting rod (410) is driven by the crank (430) to rotate.

5. The chair leg telescopic device according to claim 1, characterized in that, The sliding tube (1) and the support tube (2) are inclined backward and upward. A secondary support leg (210) inclined forward and upward is provided at the rear side of the support tube (2). The upper end of the secondary support leg (210) supports on the sliding tube (1), and the lower end of the secondary support leg (210) and the lower end of the support tube (2) jointly support on the ground.

6. The chair leg telescopic device according to claim 5, characterized in that, A roller (211) is rotatably connected to the bottom end of the secondary support leg (210). The roller (211) rolls in the front-rear direction and drives the chair leg telescopic device to move in the front-rear direction.

7. The chair leg telescopic device according to claim 1, characterized in that, The sliding tube (1) and the support tube (2) are vertically arranged. A horizontally arranged secondary support leg (210) is connected to the bottom end of the support tube (2). The secondary support leg (210) is configured to support on the ground.

8. A chair leg assembly, characterized in that, It includes two groups of chair leg telescopic devices which are symmetric left and right and are as described in any one of claims 1-7. A transmission shaft (330) is connected between the two support tubes (2). The two ends of the transmission shaft (330) are respectively connected to the left and right steering gear boxes (320). When the adjusting member (4) on one side is rotated, the left and right steering gear boxes (320) on both sides operate synchronously through the transmission of the transmission shaft (330). Further, the sliding tubes (1) on both sides can slide up and down synchronously under the transmission of the screw (310), so as to adjust the overall height of the chair leg assembly.

9. The chair leg assembly according to claim 8, characterized in that, A tubular protective sleeve (220) is transversely arranged between the support tubes (2) on both sides. The transmission shaft (330) is arranged inside the protective sleeve (220).

10. The chair leg assembly according to claim 8, characterized in that, A stop member (331) is detachably arranged on the transmission shaft (330). The stop member (331) abuts against the outer wall of one of the support tubes (3), so that the transmission shaft (330) cannot slide left and right relative to the support tube (3).

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