Linkage extending-and-retracting unit, and seat support

Abstract

Disclosed in the present application are a linkage extending-and-retracting unit and a seat support. The linkage extending-and-retracting unit comprises a supporting assembly, which comprises a base and a supporting member; a linkage assembly, which comprises a first linkage member, a second linkage member, a third linkage member and a fourth linkage member; a backrest assembly, which is hinged to the supporting member; and a leg assembly. The first linkage member and the second linkage member are both hinged between the leg assembly and the backrest assembly; the third linkage member is hinged between the backrest assembly and the supporting member and is configured to drive the backrest assembly to retract or extend or to follow along with same to retract or extend; the fourth linkage member is hinged between the first linkage member and the leg assembly and is configured to drive the leg assembly to retract or extend or to follow along with same to retract or extend; and a power source, which is provided for the backrest assembly or the third linkage member, is independent of a power source, which is provided for the leg assembly or the fourth linkage member.

Description

A linkage telescopic unit and seat bracket Technical Field

[0001] The present application relates to the technical field related to seat brackets, and in particular to a linkage telescopic unit and a seat bracket. Background Art

[0002] In the prior art, a variety of movable seat supports are known, such as sofas or seats with multi-position conversion functions. As people's living standards improve, the comfort requirements for sofas and seats are also increasing. In known designs, movable seat supports are usually equipped with a mechanical extension device, which can be transformed between a sitting position, a leisure position (i.e., a TV position) and a lying position. When the seat unit is transformed from a sitting position to a leisure position, the footrest of the leg assembly extends forward, and the angle between the backrest assembly and the seat portion remains basically unchanged. When the seat unit is transformed from a leisure position to a lying position, the footrest is further lifted forward and upward from the leisure position. Due to the linkage effect, the backrest assembly is significantly tilted back by the linkage, thereby completing the lying position of the seat unit.

[0003] In the above-mentioned seat frame, the leg assembly and the backrest assembly are usually provided with a linkage rod or linkage part to achieve a linkage effect. This causes the footrest to be in a raised position when the seat frame is lying down, which is not friendly to some people who are accustomed to lying down while sitting, and the lying down effect after sitting cannot be achieved. Summary of the Invention

[0004] To overcome at least one of the above-mentioned drawbacks of the prior art, the present application provides a linkage telescopic unit and a seat frame. The third and fourth linkages are used to control the backrest assembly and leg assembly, respectively, so that the two can be retracted or extended without interference, thereby achieving four postures: sitting, relaxing, lying, and sitting-lying reclining, thus meeting user needs.

[0005] The technical solution adopted by this application to solve the problem is:

[0006] A linkage telescopic unit comprises: a support assembly, which includes a base and a support member connected to each other; a linkage assembly, which includes a first linkage member, a second linkage member, a third linkage member and a fourth linkage member; a backrest assembly, which is hinged to the support member; a leg assembly, wherein the first linkage member and the second linkage member are respectively hinged between the leg assembly and the backrest assembly; the third linkage member is hinged between the backrest assembly and the support member, and is used to drive or follow the backrest assembly to contract or extend, the fourth linkage member is hinged between the first linkage member and the leg assembly, and is used to drive or follow the leg assembly to contract or extend, and the power source of the backrest assembly or the third linkage member is independent of the power source of the leg assembly or the fourth linkage member.

[0007] By adopting the above solution, the backrest assembly and the leg assembly can be respectively contracted or extended through the third linkage member and the fourth linkage member, avoiding a forced linkage effect between the two, thereby realizing four states of the telescopic unit.

[0008] In some embodiments, the third linkage member includes a first linkage rod and a second linkage rod, the rear end of the first linkage rod is hinged to the backrest assembly, the front end of the first linkage rod is hinged to the upper end of the second linkage rod, and the lower end of the second linkage rod is hinged to the support member.

[0009] By adopting the above solution, the rotation between the first linkage rod and the second linkage rod can change with the change of the backrest assembly, thereby achieving the independent telescopic effect of the backrest assembly.

[0010] In some embodiments, the backrest assembly includes: a first backrest member, the first backrest member includes a first backrest hinge, a second backrest hinge and a third backrest hinge, the rear end of the first linkage rod is hinged to the first backrest hinge, and the first linkage member is hinged to the second backrest hinge; a second backrest member, the second backrest member includes a fourth backrest hinge, a fifth backrest hinge and a sixth backrest hinge, the fourth backrest hinge is hinged to the third backrest hinge, the support member is hinged to the fifth backrest hinge, and the rear end of the second linkage member is hinged to the sixth backrest hinge.

[0011] By adopting the above solution, the first backrest member and the second backrest component in the backrest assembly can be extended or contracted, so that the backrest assembly can be freely switched between the standing state and the lying state.

[0012] In some embodiments, the second backrest member further includes a seventh backrest hinge point, the seventh backrest hinge point is hinged to a first auxiliary rod, and a second auxiliary rod is hinged between the first auxiliary rod and the support member.

[0013] By adopting the above solution, the stability of the backrest assembly when switching between the standing and lying states is improved, and the maximum range of its extension and contraction is limited, thereby improving the safety of the seat.

[0014] In some embodiments, the fourth linkage member includes a third linkage rod and a fourth linkage rod, the front end of the third linkage rod is hinged to the leg assembly, the rear end of the third linkage rod is hinged to the front end of the fourth linkage rod, and the rear end of the fourth linkage rod is hinged to the first linkage member.

[0015] By adopting the above solution, the extension and contraction between the third linkage rod and the fourth linkage rod can be achieved, so that the footrest of the leg assembly can be switched between the raised state and the lowered state.

[0016] In some embodiments, the leg assembly includes a first leg rod, a second leg rod, a third leg rod, a fourth leg rod and a footrest, the rear end of the first leg rod is hinged to the first linkage, the front end of the first leg rod is hinged to the rear end of the second leg rod, the rear end of the third leg rod is hinged to the first linkage, the front end of the third leg rod is hinged to the rear end of the fourth leg rod, and the second leg rod and the fourth leg rod are respectively hinged to the footrest at their front ends.

[0017] By adopting the above solution, the leg assembly can be extended and contracted, thereby achieving the lifting and lowering of the footrest.

[0018] In some embodiments, a first leg hinge and a second leg hinge are provided in the middle of the third leg rod, the front end of the third linkage rod is hinged to the first leg hinge, and the front end of the second linkage rod is hinged to the second leg hinge.

[0019] By adopting the above solution, the stability of the leg assembly when switching between the extended and contracted states can be improved.

[0020] In some embodiments, a first linkage hinge and a second linkage hinge are provided in the middle of the first linkage, the rear end of the third leg rod is hinged to the first linkage hinge, and the rear end of the fourth linkage rod is hinged to the second linkage hinge.

[0021] By adopting the above solution, the hinge effect with the fourth linkage rod and the third leg rod can be achieved.

[0022] In some embodiments, the base includes: a support plate, which is fixedly connected to the support member; a base frame, which is arranged below the support plate; a height-raising member, which is fixedly connected between the support plate and the base frame; and a buffer member, which is adjacent to the height-raising member and acts between the support plate and the base frame respectively.

[0023] By adopting the above solution, a certain support and buffering effect can be provided for the support plate, thereby improving user experience.

[0024] A seat bracket comprises at least two groups of linked telescopic units, wherein a fixing rod is connected between the support members in two adjacent groups of linked telescopic units, and a rotating square tube is provided between the first link members in two adjacent groups of linked telescopic units.

[0025] By adopting the above solution, the linkage effect of at least two groups of linkage telescopic units can be achieved.

[0026] In summary, the linkage telescopic unit and seat bracket provided by this application have the following technical effects:

[0027] 1. The design of the third and fourth linkage members allows the backrest assembly and leg assembly to be retracted or extended respectively, thus avoiding the forced linkage effect and providing more state options, including sitting and lying down;

[0028] 2. The design of the leg assembly allows the footrest to switch between raised and lowered positions to meet different needs;

[0029] 3. The design of the first and second auxiliary rods improves the stability of the backrest assembly when switching between the upright and reclining positions, while limiting the maximum range of extension and contraction, thereby increasing the safety of the seat;

[0030] 4. Through the setting of fixed rods and rotating square tubes, multiple groups of linkage telescopic units can be linked, increasing the flexibility and applicability of the seat;

[0031] 5. The support plates, heightening parts and buffer parts in the support parts can provide support and buffering for the seat, improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of a side view of a sitting posture structure according to an embodiment of the present application;

[0033] FIG2 is a schematic diagram of the side structure of the sitting and lying position according to an embodiment of the present application;

[0034] FIG3 is a schematic diagram of the side structure of a TV posture according to an embodiment of the present application;

[0035] FIG4 is a schematic diagram of a side structure of a lying position according to an embodiment of the present application;

[0036] FIG5 is a schematic diagram of a three-dimensional structure of a sitting posture according to an embodiment of the present application;

[0037] FIG6 is a schematic diagram of a three-dimensional structure of a sitting and lying position according to an embodiment of the present application;

[0038] FIG7 is a schematic diagram of a three-dimensional structure of a TV in an embodiment of the present application;

[0039] FIG8 is a schematic diagram of a three-dimensional structure of a lying position according to an embodiment of the present application

[0040] FIG9 is a schematic diagram of the three-dimensional structure of the support assembly according to an embodiment of the present application

[0041] FIG10 is a schematic diagram of the linkage structure of the leg assembly and the fourth linkage member according to an embodiment of the present application

[0042] FIG11 is a schematic diagram of the linkage structure between the backrest assembly and the third linkage member according to an embodiment of the present application.

[0043] The meanings of the accompanying drawings are as follows: 1. support assembly; 11. base; 111. footrest; 112. connecting rib; 113. support plate; 114. height-increasing member; 12. support member; 13. buffer member; 2. linkage assembly; 21. first linkage member; 211. first hinge point of linkage member; 212. second hinge point of linkage member; 22. second linkage member; 23. third linkage member; 231. first linkage rod; 232. second linkage rod; 24. fourth linkage member; 241. third linkage rod; 242. fourth linkage rod; 3. backrest assembly; 31. first backrest member; 311. First hinge point of backrest; 312. Second hinge point of backrest; 313. Third hinge point of backrest; 32. Second backrest component; 321. Fourth hinge point of backrest; 322. Fifth hinge point of backrest; 323. Sixth hinge point of backrest; 324. Seventh hinge point of backrest; 33. First auxiliary rod; 34. Second auxiliary rod; 4. Leg assembly; 41. First leg rod; 411. Limiting structure; 42. Second leg rod; 43. Third leg rod; 431. First hinge point of leg; 432. Second hinge point of leg; 44. Fourth leg rod; 45. Footrest; 5. Fixing rod; 6. Rotating square tube. DETAILED DESCRIPTION

[0044] For better understanding and implementation, the technical solutions in the embodiments of the present application will be clearly and completely described and discussed below in conjunction with the drawings of the present application. Obviously, what is described here is only a part of the examples of the present application, not all the examples. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0045] In order to facilitate the understanding of the embodiments of the present application, further explanation will be given below with reference to specific embodiments as examples in conjunction with the drawings, and each embodiment does not constitute a limitation on the embodiments of the present application.

[0046] In the description of this application, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting this application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0048] The embodiment 1 of the present application, as shown in Figures 1 to 11, discloses a linkage telescopic unit, including a support assembly 1, a linkage assembly 2, a backrest assembly 3 and a leg assembly 4. Specifically, the support assembly 1 includes a base 11 and a support member 12 connected to each other, the linkage assembly 2 includes a first linkage member 21, a second linkage member 22, a third linkage member 23 and a fourth linkage member 24, the backrest assembly 3 is hinged to the support member 12, the first linkage member 21 and the second linkage member 22 are respectively hinged between the leg assembly 4 and the backrest assembly 3; the third linkage member 23 is hinged between the backrest assembly 3 and the support member 12, and is used to drive or follow the backrest assembly 3 to retract or extend. The fourth linkage member 24 is hinged between the first linkage member 21 and the leg assembly 4, and is used to drive or follow the leg assembly 4 to contract or extend. The contraction or extension of the backrest assembly 3 and the leg assembly 4 can be achieved respectively by the third linkage member 23 and the fourth linkage member 24, avoiding a forced linkage effect between the two. The power source of the backrest assembly 3 or the third linkage member 23 is independent of the power source of the leg assembly 4 or the fourth linkage member 24. The power source includes but is not limited to the power effect brought by manual drive and motor drive. The usual manual drive method is to directly act on the sofa surface, and the motor drive method is to directly act on the third linkage member 23 or the fourth linkage member 24. Therefore, the following four states of the telescopic unit can be realized: the first state is the sitting state, as shown in Figures 1 and 5, in which the backrest assembly 3 and the leg assembly 4 are both retracted; the second state is the sitting lying state, as shown in Figures 2 and 6, in which the backrest assembly 3 is extended and the leg assembly 4 is retracted; the third state is the TV posture, as shown in Figures 3 and 7, in which the backrest assembly 3 is retracted and the leg assembly 4 is extended; the fourth state is the fully lying state, as shown in Figures 4 and 8, in which the backrest assembly 3 and the leg assembly 4 are both extended.

[0049] In order to better achieve the purpose of switching the leg assembly 4 between the two states, the fourth linkage member 24 is described in detail. In this embodiment 1, as shown in Figure 10, the fourth linkage member 24 includes a third linkage rod 241 and a fourth linkage rod 242. A first linkage member hinge 211 and a second linkage member hinge 212 are provided in the middle of the first linkage member 21. The leg assembly 4 includes a first leg rod 41, a second leg rod 42, a third leg rod 43, a fourth leg rod 44 and a footrest 45. The rear end of the first leg rod 41 is hinged to the front end of the first linkage member 21, the front end of the first leg rod 41 is hinged to the rear end of the second leg rod 42, the rear end of the third leg rod 43 is hinged to the linkage member first hinge 211 of the first linkage member 21, the front end of the third leg rod 43 is hinged to the rear end of the fourth leg rod 44, the second leg rod 42 and the fourth leg rod 44 are hinged to the footrest 45 at their front ends respectively, which can realize the extension and contraction states of the leg assembly 4, and thus realize the lifting and lowering of the footrest 45. A first leg hinge 431 and a second leg hinge 432 are provided in the middle of the third leg rod 43, the front end of the third linkage rod 241 is hinged to the first leg hinge 431 in the leg assembly 4, the front end of the second linkage member 22 is hinged to the second leg hinge 432, the rear end of the third linkage rod 241 is hinged to the front end of the fourth linkage rod 242, and the rear end of the fourth linkage rod 242 is hinged to the second linkage hinge 212 in the first linkage member 21, so that the footrest 45 of the leg assembly 4 can be switched between the raised state and the lowered state.

[0050] In order to better achieve the purpose of switching between the two states of the backrest assembly 3, the third linkage member 23 is described in detail. In this embodiment 1, as shown in Figure 11, the third linkage member 23 includes a first linkage rod 231 and a second linkage rod 232, and the backrest assembly 3 includes a first backrest member 31 and a second backrest member 32. The first backrest member 31 includes a first backrest hinge point 311, a second backrest hinge point 312 and a third backrest hinge point 313, and the second backrest member 32 includes a fourth backrest hinge point 321, a fifth backrest hinge point 322 and a sixth backrest hinge point 323. The rear end of the first linkage rod 231 is hinged to the first hinge point 311 of the backrest assembly 3, the rear end of the first linkage member 21 is hinged to the second hinge point 312 of the backrest assembly 3, the fourth hinge point 321 is hinged to the third hinge point 313 of the backrest, the support member 12 is hinged to the fifth hinge point 322 of the backrest, and the rear end of the second linkage member 22 is hinged to the sixth hinge point 323 of the backrest. These structures enable the first backrest member 31 and the second backrest member 3 of the backrest assembly 3 to extend or retract, allowing the backrest assembly 3 to freely switch between an upright and a reclined position. The front end of the first linkage rod 231 is hinged to the upper end of the second linkage rod 232, and the lower end of the second linkage rod 232 is hinged to the support member 12. This allows the rotation between the first linkage rod 231 and the second linkage rod 232 to change with the backrest assembly 3, thereby achieving the independent extension and retraction effect of the backrest assembly 3.

[0051] In some embodiments, referring to FIG11 , in order to improve the stability of the backrest assembly 3 in switching between the standing and lying states, a seventh backrest hinge 324 is further provided on the second backrest member 32, and the seventh backrest hinge 324 is hinged to a first auxiliary rod 33, and a second auxiliary rod 34 is hinged between the first auxiliary rod 33 and the support member 12, which can improve the stability of the backrest assembly 3 in switching between the standing and lying states while limiting its maximum range of extension and contraction, thereby improving the safety of the seat.

[0052] The present application also designs a seat bracket, comprising at least two groups of linked telescopic units, as shown in Figures 5-8. In this embodiment 1, the linked telescopic units are arranged in two groups, and a fixed rod 5 is connected between the support members 12 in the two adjacent groups of linked telescopic units. A rotating square tube 6 is provided between the first linkage members 21 in the two adjacent groups of linked telescopic units, which can achieve a linkage effect of at least two groups of linked telescopic units. Specifically, the rotating square tube 6 passes through the two first linkage members 21 and is fixedly connected to the rear end of the fourth linkage rod 242.

[0053] In order to improve the supporting stability of the seat frame, referring to Figure 9, the base 11 includes a bottom frame, a support plate 121 and a height-increasing member 122. The bottom frame includes at least two legs 111, and at least two connecting ribs 112 are provided between the two legs 111 to improve the fixing effect of the legs 111, thereby improving the supporting stability of the bottom frame. In this embodiment 1, two support members 12 are provided, and a support plate 121 and a heightening member 122 are provided below each support member 12. The support plate 121 is an L-shaped plate. The upper portion of the L-shaped plate of the support plate 121 is connected to the support member 12, and the connection method is not limited to integral connection, welding, or screw connection. The lower portion of the L-shaped plate of the support plate 121 is connected to the heightening member 122, and the connection method is not limited to integral connection, welding, or screw connection. The bottom end of the heightening member 122 is fixed to the base 11, and the fixing method is not limited to welding or screw connection. Since each support plate 121 is connected to a support member 12, each support plate 121 corresponds to a group of linked telescopic units. A fixing rod 5 is connected between the support plates 121 of two adjacent groups of linked telescopic units. The ends of the fixing rod 5 can also pass through the support plate 121 to be fixed to the support member 12. The shape of the heightening member 122 is not specifically limited, and it can be integrally formed with the support plate 121.

[0054] To enhance the cushioning capacity of the seat frame, as shown in FIG9 , some embodiments further include a buffer member 13 . This buffer member 13 is positioned adjacent to the height-raising member 122 and acts on the underside of the fixing rod 5 of the support plate 121 and the top of the connecting rib 112 of the base 11 , providing support and cushioning for the support plate 121 and improving the user experience. In this first embodiment, in some implementations, the buffer member 13 utilizes an anti-vibration spring. It should be noted that if the buffer member 13 is not required, the height-raising member 122 can be omitted, and the support plate 121 can be directly connected to the base 11.

[0055] In order to enable the backrest assembly 3 and the leg assembly 4 to achieve intelligent extension and retraction, in some embodiments, two drive motors can be added, and the drive motors include but are not limited to slider motors or telescopic rod motors. The above-mentioned drive motors can be used to control the backrest assembly 3 and the leg assembly 4 separately, thereby achieving intelligent control.

[0056] In some embodiments, a return spring can also be provided between the backrest assembly 3 and the third linkage member 23 to assist the backrest in retracting and retracting; preferably, the return spring is connected between the first linkage rod 231 and the support member 12, or between the first linkage rod 231 and the second backrest member 32.

[0057] When the user is in use, the chair is in a sitting position, and the user sits on the chair. When the user needs to lie down from a sitting position, the first backrest member 31 and the second backrest member 32 in the backrest assembly 3 are rotated and extended by driving a motor or manually adjusting, so that the first backrest member 31 rotates toward the rear end to achieve a lying position. When the user needs to lie down, the leg assembly 4 is extended by driving a motor or manually adjusting to achieve a fully lying position. When the user needs to adopt a TV posture, the first backrest member 31 and the second backrest member 32 in the backrest assembly 3 are rotated and retracted by driving a motor or manually adjusting, so that the first backrest member 31 rotates toward the front end to achieve an upright position, thereby completing the transition to a TV posture.

[0058] In summary, the linkage telescopic unit and seat bracket provided by this application have the following technical effects:

[0059] 1. The design of the third linkage member 23 and the fourth linkage member 24 allows the backrest assembly 3 and the leg assembly 4 to be retracted or extended, respectively, thereby avoiding a forced linkage effect and providing more state options, including sitting and lying down;

[0060] 2. The design of the leg assembly 4 enables the footrest 45 to switch between a raised state and a lowered state to meet different needs;

[0061] 3. The design of the first auxiliary rod 33 and the second auxiliary rod 34 improves the stability of the backrest assembly 3 when switching between the upright and reclining positions, while limiting the maximum range of extension and contraction, thereby increasing the safety of the seat;

[0062] 4. Through the arrangement of the fixed rod 5 and the rotating square tube 6, multiple groups of linkage telescopic units can be linked, increasing the flexibility and applicability of the seat;

[0063] 5. The support plate 121, the height-increasing member 122 and the buffer member 13 in the support member 12 can provide support and buffering for the seat, thereby improving the user experience.

[0064] The technical means disclosed in the present application are not limited to those disclosed in the above-mentioned embodiments, but also include technical solutions composed of any combination of the above-mentioned technical features. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present application, and such improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A linkage telescopic unit, comprising: A support assembly (1), comprising a base (11) and a support member (12) connected to each other; A linkage assembly (2), the linkage assembly (2) comprising a first linkage member (21), a second linkage member (22), a third linkage member (23) and a fourth linkage member (24); a backrest assembly (3), the backrest assembly (3) being hinged to the support member (12); A leg assembly (4), wherein the first linkage member (21) and the second linkage member (22) are respectively hinged between the leg assembly (4) and the backrest assembly (3); The third linkage member (23) is hinged between the backrest assembly (3) and the support member (12), and is used to drive or follow the backrest assembly (3) to contract or extend. The fourth linkage member (24) is hinged between the first linkage member (21) and the leg assembly (4), and is used to drive or follow the leg assembly (4) to contract or extend. The power source of the backrest assembly (3) or the third linkage member (23) is independent of the power source of the leg assembly (4) or the fourth linkage member (24).

2. A linkage telescopic unit according to claim 1, wherein: The third linkage member (23) comprises a first linkage rod (231) and a second linkage rod (232), wherein the rear end of the first linkage rod (231) is hinged to the backrest assembly (3), the front end of the first linkage rod (231) is hinged to the upper end of the second linkage rod (232), and the lower end of the second linkage rod (232) is hinged to the support member (12).

3. A linkage telescopic unit according to claim 2, wherein: The backrest assembly (3) comprises: A first backrest member (31), the first backrest member (31) comprising a first backrest hinge point (311), a second backrest hinge point (312), and a third backrest hinge point (313); a rear end of the first linkage rod (231) is hinged to the first backrest hinge point (311), and the first linkage member (21) is hinged to the second backrest hinge point (312); A second backrest member (32), the second backrest member (32) includes a fourth backrest hinge point (321), a fifth backrest hinge point (322) and a sixth backrest hinge point (323), the fourth backrest hinge point (321) is hinged to the third backrest hinge point (313), the support member (12) is hinged to the fifth backrest hinge point (322), and the rear end of the second linkage member (22) is hinged to the sixth backrest hinge point (323).

4. A linkage telescopic unit according to claim 3, wherein: The second backrest member (32) further includes a seventh backrest hinge point (324), the seventh backrest hinge point (324) is hinged to a first auxiliary rod (33), and a second auxiliary rod (34) is hinged between the first auxiliary rod (33) and the support member (12).

5. The linkage telescopic unit according to claim 1, wherein: The fourth linkage member (24) comprises a third linkage rod (241) and a fourth linkage rod (242), wherein the front end of the third linkage rod (241) is hinged to the leg assembly (4), the rear end of the third linkage rod (241) is hinged to the front end of the fourth linkage rod (242), and the rear end of the fourth linkage rod (242) is hinged to the first linkage member (21).

6. A linkage telescopic unit according to claim 5, wherein: The leg assembly (4) comprises a first leg rod (41), a second leg rod (42), a third leg rod (43), a fourth leg rod (44) and a footrest (45), wherein the rear end of the first leg rod (41) is hinged to the first linkage member (21), the front end of the first leg rod (41) is hinged to the rear end of the second leg rod (42), the rear end of the third leg rod (43) is hinged to the first linkage member (21), the front end of the third leg rod (43) is hinged to the rear end of the fourth leg rod (44), and the second leg rod (42) and the fourth leg rod (44) are hinged to the footrest (45) at their front ends respectively.

7. A linkage telescopic unit according to claim 6, wherein: A first leg hinge (431) and a second leg hinge (432) are provided in the middle of the third leg rod (43); the front end of the third linkage rod (241) is hinged to the first leg hinge (431); and the front end of the second linkage member (22) is hinged to the second leg hinge (432).

8. The linkage telescopic unit according to claim 6, wherein: A first linkage member hinge point (211) and a second linkage member hinge point (212) are provided in the middle of the first linkage member (21); a rear end of the third leg rod (43) is hinged to the first linkage member hinge point (211); and a rear end of the fourth linkage rod (242) is hinged to the second linkage member hinge point (212).

9. A linkage telescopic unit according to any one of claims 1 to 8, wherein: The base (11) comprises: a support plate (121), the support plate (121) being fixedly connected to the support member (12); A bottom frame, the bottom frame being arranged below the support plate (121); A height-raising member (122), the height-raising member (122) being fixedly connected between the support plate (121) and the base frame; A buffer member (13) is provided adjacent to the height-increasing member (122) and acts between the support plate (121) and the base frame.

10. A seat support, comprising at least two sets of the linkage telescopic units according to any one of claims 1 to 8, wherein: A fixed rod (5) is connected between the support members (12) in two adjacent groups of linked telescopic units, and a rotating square tube (6) is provided between the first linked members (21) in two adjacent groups of linked telescopic units.

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