An extension device and a movable sofa

Abstract

This application relates to an extension device and a movable sofa. The extension device includes a base, a seat frame assembly, a footrest assembly, and a backrest assembly. The seat frame assembly includes a seat frame plate, a support rod, a front linkage rod, and a rear linkage rod. The head of the support rod is connected to the base and can rotate relative to the base. The tail of the support rod is connected to the footrest assembly. The base has a first fulcrum to limit the deflection of the tail of the support rod. The front linkage rod is hinged between the seat frame plate and the support rod. The tail of the base has a second fulcrum to limit the lifting of the front linkage rod. The rear linkage rod is hinged between the seat frame plate and the base. When the backrest assembly drives the seat frame plate to move laterally relative to the base, the seat frame plate drives the front linkage rod to disengage from the lifting restriction of the second fulcrum. This application solves the problem of the extension device changing from a sitting to a reclining position due to pressure on the backrest assembly, achieving high structural strength, stable and smooth posture switching of the extension device.

Description

Technical Field

[0001] This application relates to the field of sofas, and more particularly to an extension device and a movable sofa. Background Technology

[0002] With the improvement of domestic productivity and the development of the social economy, people's living standards are getting higher and higher, and their requirements for furniture are also getting higher and higher. Sofas, rocking chairs, and chairs are ubiquitous. Some sofas not only have extendable footrests, but also adjustable seat height and backrest angles.

[0003] Currently, folding sofas or chairs generally use internal electric or manual mechanical extension mechanisms to switch between different positions. Manual mechanical extension mechanisms on the market mainly have two or three posture-changing structures. The three-posture extension mechanisms include a base, backrest assembly, seat frame assembly, and footrest assembly. By applying force to the backrest assembly while on the seat frame assembly, the mechanical extension mechanism changes from a sitting position to a relaxed position. When the mechanical extension mechanism is in the relaxed position, the user applies force to the backrest assembly again, causing the mechanical extension mechanism to change from the relaxed position to a reclining position.

[0004] Regarding the aforementioned technologies, the inventors believe that the following defects exist: when the upper end of the seat frame assembly is not under pressure, the backrest assembly is leaned against and pressure is applied. If the pressure is too great, the seat frame assembly will be directly lifted by the pressure of the leaning, thus forming a reclining posture and causing a problem of posture confusion. Summary of the Invention

[0005] To address the issue of posture confusion in stretching devices, this application provides a stretching device and its movable sofa.

[0006] In a first aspect, this application provides a stretching device, which adopts the following technical solution:

[0007] A mechanical extension device includes a base, a seat frame assembly, a footrest assembly, and a backrest assembly. The backrest assembly is connected to the front end of the seat frame assembly and the base, and the footrest assembly is connected to the rear end of the seat frame assembly for moving the seat frame assembly relative to the base. The seat frame assembly includes a seat frame plate, a support rod, a front linkage rod, and a rear linkage rod. The front end of the support rod is connected to the base and is rotatable relative to the base, and the rear end of the support rod is connected to the footrest assembly. The base has a first fulcrum that limits the deflection of the rear end of the support rod. The front linkage rod is hinged between the seat frame plate and the support rod. When the backrest assembly drives the seat frame plate to move laterally relative to the base, the seat frame plate drives the front linkage rod to disengage from the lifting restriction of the second fulcrum.

[0008] By adopting the above technical solution, in the initial state of the mechanical extension device, the second fulcrum is used to hold the bottom end of the front linkage rod. When no pressure is applied to the upper end of the seat frame assembly, applying a downward force to the top of the backrest assembly will cause the seat frame plate and the tail end of the support rod to rise. Since the front linkage rod is held in place by the second fulcrum and cannot rise, it acts as a limit for the seat frame plate and the support rod. Only when a person sits on the seat frame assembly and applies a backward force to the backrest assembly will the bottom frame plate move laterally towards the backrest, causing the front linkage rod to move away from the second fulcrum. Only after the front linkage rod loses its limit can the seat frame plate rise. This achieves the effect of not being able to achieve a reclining posture even if the backrest assembly is moved when no one is sitting, thus improving the problem of accidental operation.

[0009] Optionally, the front linkage rod is hinged to the end of the support rod and extends to provide an abutment portion. The abutment portion is hook-shaped and forms a groove. The abutment portion is located on the side wall of the groove and abuts against the second fulcrum. The second fulcrum abuts against the abutment portion and prevents the front linkage rod from moving upward.

[0010] By adopting the above technical solution, the hook-shaped contact structure between the contact part and the second fulcrum realizes the open limiting structure of the contact part, which facilitates the release of the limiting position later.

[0011] Optionally, the second fulcrum is a rivet structure, and the abutting part is provided with an abutting surface on the side wall of the groove. The abutting surface is provided with at least two contact points that fit with the circumferential side of the second fulcrum.

[0012] By adopting the above technical solution, the limiting rivet abuts against the contact surface of the groove, thereby limiting the seat frame plate. The contact point can abut against multiple points of the second support point, ensuring the stability of the limiting rivet after it is abutted in the groove, and making it less likely to come off.

[0013] Optionally, the tail of the support rod is located at the upper end of the second fulcrum, and the support rod is provided with a groove that abuts against the second fulcrum.

[0014] By adopting the above technical solution, the second fulcrum not only limits the front linkage rod but also supports the tail of the support rod, sharing the limiting force of the first fulcrum on the support rod and extending its service life.

[0015] Optionally, the rear linkage rod includes a first connecting rod and a second connecting rod. The tail of the first connecting rod is hinged to the base, and the second connecting rod is hinged between the head of the first connecting rod and the seat frame plate. The base is provided with a third fulcrum to restrict the lifting of the rear linkage rod. The third fulcrum is a first guide groove, and the second connecting rod is provided with a first movable member that passes through the first guide groove.

[0016] By adopting the above technical solution, the seat frame plate can freely rotate within the restricted orientation through the first connecting rod and the second connecting rod, and the first guide groove plays a role in limiting the movement of the first moving part.

[0017] Optionally, the first guide groove includes a first groove and a second groove that are connected. The second groove is located between the first groove and the backrest assembly. A turning area is formed at the connection between the head of the first groove and the tail of the second groove. The first moving member moves horizontally along the first groove and moves vertically along the second groove.

[0018] By adopting the above technical solution, the third fulcrum is restricted by the first guide groove. When the backrest assembly and footrest assembly are simultaneously subjected to opposing forces, the seat frame plate can only move along the track of the first guide groove, ensuring that the sitting posture, leisure posture and reclining posture are opened and deformed in sequence, thus avoiding the problem of chaotic posture changes.

[0019] Optionally, the tail of the first groove is located below the turning area, the first groove has an arc-shaped structure, and the head of the second groove forms an inclined angle towards the backrest assembly.

[0020] By adopting the above technical solution, the arc-shaped structure of the first groove plays a buffering role. Compared with the straight structure, it reduces the impact force of the seat frame plate moving into place instantly, making the shape transformation process more stable and comfortable.

[0021] Optionally, the footrest assembly includes an input component and a support component that unfolds under the drive of the input component. A force spring is connected between the input component and the seat frame plate. The force spring reaches its maximum elongation during the unfolding process of the footrest assembly. The elongation of the force spring in both the unfolded and retracted states of the footrest assembly is less than this maximum elongation. The rotation direction of the force spring is consistent with the rotation direction of the abutment portion.

[0022] By adopting the above technical solution, on the one hand, the function is similar to that of a pre-tension spring, so that the footrest component requires the user to apply force to unfold. Therefore, simply applying pressure to the backrest component cannot drive the footrest component to unfold. On the other hand, the inability of the footrest component to unfold means that the abutment part is still in the state of abutting against the first fulcrum, which further improves the limiting effect of the front linkage rod on the seat frame plate.

[0023] Secondly, this application provides a movable sofa, which adopts the following technical solution:

[0024] A movable sofa includes two extension devices arranged symmetrically, with a crossbeam fixed between the bases of the two extension devices.

[0025] By adopting the above technical solution, users can change between sitting, relaxing, and lying positions by applying pressure to the backrest component while sitting on the sofa. Simply relying on the backrest component does not allow for such changes, thus improving safety.

[0026] Optionally, a linkage beam connects the two foot assemblies, and a telescopic drive is hinged to the crossbeam, with the output end of the telescopic drive hinged to the linkage beam.

[0027] By adopting the above technical solution, an additional power source can be added to achieve automatic rotation, thus improving the ease of use.

[0028] In summary, this application includes at least one of the following beneficial technical effects:

[0029] When the extension device is in the seated position, the force spring limits the footrest assembly; force must be applied to the footrest assembly for it to unfold. When there is no pressure on the upper end of the seat frame assembly, applying pressure to the backrest insert causes the seat frame plate to move towards the backrest assembly before lifting due to the structure of the first guide groove. If the seat frame plate moves towards the backrest assembly, the tail end of the seat frame plate will lift upwards because the footrest assembly is not open. At this time, the abutment part of the front linkage rod is blocked by the first fulcrum, thus pulling the tail end of the seat frame plate upwards, preventing the second fulcrum from moving within the first guide groove. Therefore, the force spring, the first support point, and the second support point mutually restrain each other when in the seated position. Even when applying pressure to the backrest assembly, the seat frame assembly will not move or lift, making the extension device's structure in the seated position more compact and stable, and mitigating the problem of accidental operation causing the seated position to directly become a reclining position.

[0030] During the unfolding process, the tension of the spring in the footrest assembly will change from small to large to small. On the one hand, when the user pulls the footrest assembly out, they only need to apply force in the process of small to large. When the tension changes from large to small, no pressure needs to be applied and the footrest assembly will automatically continue to unfold. On the other hand, after the user unfolds the footrest assembly, there is no need to continuously apply force to the backrest or seat frame to keep the footrest assembly in the unfolded state.

[0031] The first guide groove guides and limits the movement of the seat frame plate, allowing it to move only along the direction of the first guide groove. To move, the footrest assembly must first be opened. After opening, the seat frame plate can be raised upward along the second groove, thereby achieving the leisure posture and the reclining posture in sequence, avoiding confusion in posture that could cause injury to the human body and reduce user satisfaction. The second guide groove, in conjunction with the second groove of the first guide groove, makes the seat frame plate more stable during the lifting process, preventing the problem of lateral swaying and improving the comfort of use.

[0032] This device is easy to use, achieving switching between different postures by rationally distributing the weight of various parts of the human body. It not only meets the needs of different postures but also allows for simple and convenient control of the device's extension sequence. Furthermore, through a rational structural design, a simple and compact arrangement is used to construct the linkage mechanism, making the device operate more smoothly and stably, with stronger and more robust connections. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of Example 1.

[0034] Figure 2 This is a structural schematic diagram of one side of the seated posture of the extension device in Embodiment 1, wherein the base is cut off to allow the structure obscured by the base to be seen.

[0035] Figure 3 This is a structural schematic diagram of another side of the seated posture of the extension device in Embodiment 1.

[0036] Figure 4 yes Figure 2 A diagram illustrating a relaxed posture using the stretching device.

[0037] Figure 5 yes Figure 2 A schematic diagram of the extension device in a supine position.

[0038] Figure 6 This is a schematic diagram of the structure of the movable sofa in Example 2.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Base; 2. Seat frame assembly; 21. Seat frame plate; 22. Support rod; 23. Front linkage rod; 231. Abutment part; 232. Groove; 234. Abutment surface; 235. Recess; 24. Rear linkage rod; 241. First connecting rod; 242. Second connecting rod; 25. Bending part; 3. Foot rest assembly; 31. Input component; 311. Foot rest linkage rod; 312. Front foot rest connector; 313. Rear foot rest connector; 32. Support component; 321. Extended foot rest plate 322. Footrest connecting rod; 323. First leg connecting rod; 324. Second leg connecting rod; 325. Footrest bracket; 33. Force-bearing spring; 4. Backrest assembly; 41. Backrest insert; 42. Backrest support; 43. Anti-rotation pin; 5. First fulcrum; 6. Second fulcrum; 7. Third fulcrum; 71. First groove; 72. Second groove; 73. Turning area; 8. First moving part; 9. Second moving part; 10. Crossbeam; 11. Linkage beam; 12. Telescopic drive part. Detailed Implementation

[0041] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0042] This application discloses an extension device and a movable sofa.

[0043] Example 1:

[0044] Reference Figure 1 As shown, a mechanical extension device is typically used in pairs symmetrically, with the two extension devices fixed together by a crossbeam 10. Each mechanical extension device includes a base 1, a base 1 assembly, a backrest assembly 4 for mounting the backrest, and a footrest assembly 3 for mounting the foot pad. The base 1 serves as the mounting foundation for the extension device and is generally installed on the bottom support of the furniture, remaining fixed throughout the entire posture change of the extension device. In this embodiment, a sofa is used as an example, but it is not limited to sofas. The sofa cushion can be installed on the seat frame assembly 2 or on the base 1; this embodiment uses installation on the base 1 as an example.

[0045] Reference Figure 1 As shown, the seat frame assembly 2 is located inside the sofa cavity. When the extension device changes posture, it provides motion transmission to the backrest assembly 4 and the footrest assembly 3, and mutually restricts their movement trajectories. This allows the seat frame assembly 2 to move relative to the base 1, enabling changes in the position and angle of the backrest and footrest relative to the seat cushion. For ease of orientation description, the end where the base 1, seat frame assembly 2, and backrest assembly 4 are hinged is considered the head, and the end where the base 1, seat frame assembly 2, and footrest assembly 3 are hinged is considered the tail.

[0046] Reference Figure 2 and Figure 3 As shown, the seat frame assembly 2 includes a seat frame plate 21, a support rod 22, a front linkage rod 23, and a rear linkage rod 24. The middle part of the support rod 22 has a curved structure, and this curved part forms a clearance space with the base 1. The rear linkage rod 24 includes a first connecting rod 241 and a second connecting rod 242. The first connecting rod 241 passes through the clearance space of the support rod 22 and can rotate freely within the clearance space. The second connecting rod 242 has an L-shaped structure. One end of the second connecting rod 242 is hinged to the seat frame plate 21, and the other end of the second connecting rod 242 is hinged to the first connecting rod 241. The included angle opening of the second connecting rod 242 is set towards the backrest assembly 4.

[0047] Reference Figure 2 and Figure 5As shown, the third fulcrum 7 is the first guide groove, and the second connecting rod 242 is provided with a first moving member 8 that passes through the first guide groove. The first moving member 8 is a guide rivet. The first guide groove includes a first groove body 71 and a second groove body 72 that are connected. The connection between the first groove body 71 and the second groove body 72 forms a turning area 73. The second groove body 72 is located between the first groove body 71 and the backrest assembly 4. The end of the second groove body 72 located in the turning area 73 is higher than the other end. The first groove body 71 has an upwardly extending arc-shaped structure. The first moving member 8 moves horizontally along the first groove body 71 toward the backrest assembly 4 and moves slightly upward to the turning area 73. The second groove body 72 is slightly inclined toward the backrest assembly 4. The end of the second groove body 72 located in the turning area 73 is lower than the other end. The first moving rod is lifted upward from the turning area 73 along the second groove body 72.

[0048] Reference Figure 2 and Figure 5 As shown, the first fulcrum 5 is located at the tail of the base 1. The first fulcrum 5 is a second guide groove, which is vertically arc-shaped, and the inclination direction of the arc is the same as the inclination direction of the second groove body 72. The support rod 22 is provided with a second movable member 9 that passes through the second guide groove. The second movable member 9 is a flange rivet, and the rotation of the support rod 22 is restricted by the sliding of the second movable member 9 in the second guide groove.

[0049] At this point, the seat frame plate 21 can be considered to have a changing path with two stages relative to the first support point 5 and the third support point 7. (Refer to...) Figures 3 to 4 As shown, in the first stage, the user applies force to the backrest assembly 4. The first moving part 8 moves diagonally upward along the arc of the first groove 71, with the upward angle not being too large. Then, the linkage rod 24 drives the seat frame plate 21 to tilt downward towards the backrest. At this time, the second moving part 9 remains stationary at the bottom of the second guide groove, and the extension device changes from a sitting posture to a relaxed posture. (Refer to...) Figures 4 to 5 As shown, in the second stage, when the user continues to apply force backward to the backrest assembly 4, the first moving member 8 continues to move upward along the second groove 72, while the second moving member 9 moves upward along the second guide groove, and the seat frame plate 21 is stably raised, changing the extension device from a relaxed posture to a reclining posture. Conversely, when the second pressure applied to the backrest assembly 4 is removed, the first moving member 8 first moves downward from the second groove 72 into the transition zone 73, changing the extension device from a reclining posture to a relaxed posture; when the first pressure applied to the backrest assembly 4 is removed, the first moving member 8 continues to move towards the rear along the first groove 71, changing the extension device from a relaxed posture to a sitting posture.

[0050] Reference Figure 2 and Figure 3As shown, the rear of the seat frame plate 21 is provided with a protruding curved portion 25. The front linkage rod 23 is bent at an obtuse angle. One end of the front linkage rod 23 is hinged to the curved portion 25, and the other end is hinged to the support rod 22 and extends to abutment portion 231. The abutment portion 231 is hook-shaped and has an arc-shaped groove. The rear of the base 1 is equipped with a second fulcrum 6, which is a rivet structure for limiting the position. The abutment portion 231 is located on the side wall of the groove 232 and forms an abutment surface 234. The abutment surface 234 is an arc-shaped concave surface and is tangent to the circumferential side of the rivet, achieving a tighter fit.

[0051] At this point, the front linkage 23 relative to the second fulcrum 6 can be considered as having a three-stage change path: (Refer to...) Figure 2 and Figure 3 As shown, in the first stage, the extension device is in a seated position. When the seat frame assembly 2 is stationary relative to the base 1, the front linkage rod 23 is located between the footrest assembly 3 and the base 1. One end of the front linkage rod 23 is hinged to the seat frame plate 21 and faces the footrest assembly 3. The abutment part 231 has an arc-shaped concave surface on the side wall of the groove 232. The axial side of the limiting rivet fits into the side wall of the groove 232 of the abutment part 231. When the front linkage rod 23 moves upward, the limiting rivet restricts the arc-shaped concave surface, and the front linkage rod 23 cannot be raised.

[0052] Reference Figure 3 and Figure 4 As shown, in the second stage, during the process of the extension device changing from a sitting posture to a leisure posture, due to the restriction of the first guide groove, the seat frame plate 21 first moves relative to the base 1 towards the backrest assembly 4 and tilts downward, causing one end of the front linkage rod 23 to move towards the backrest assembly 4. Due to the limitation of the limiting rivet on the front linkage rod 23, the abutting part 231 of the front linkage rod 23 moves towards the footrest assembly 3, the side wall of the groove 232 leaves the limiting rivet and is set diagonally downward, and the front linkage rod 23 is in a liftable state.

[0053] Reference Figure 4 and Figure 5 As shown, in the third stage, during the transition of the extension device from a relaxed posture to a reclining posture, a backward force continues to be applied to the backrest assembly 4, and the tail of the seat frame plate 21 continues to rise along the first guide groove, while the front linkage rod 23 moves above the second fulcrum 6. At this time, the groove 232 of the abutment part 231 faces the second fulcrum 6, so that when it is necessary to return to a sitting posture, the groove 232 of the abutment part 231 can better engage below the first fulcrum 5.

[0054] Reference Figure 3 and Figure 4As shown, the footrest assembly 3 includes an input component 31 and a support component 32 that unfolds under the action of the input component 31. The input component 31 includes a footrest linkage rod 311, a front footrest connector 312, and a rear footrest connector 313. The support component 32 includes an extended footrest plate 321, a footrest connecting rod 322, a footrest bracket 325, a first leg connecting rod 323, and a second leg connecting rod 324. The first parts of the front footrest connector 312 and the rear footrest connector 313 are respectively hinged to the curved portion 25 of the seat frame plate, and the hinge point of the front footrest connector 312 is located above the hinge point of the rear footrest connector 313.

[0055] Reference Figure 4 and Figure 5 As shown, the footrest linkage rod 311 is bent into an L-shaped structure. The head of the footrest linkage rod 311 is hinged to the tail of the support rod 22, and the tail of the footrest linkage rod 311 is hinged to the front footrest connecting rod 322. The tail of the rear footrest connector 313 is hinged to the head of the second leg connecting rod 324, and the tail of the second leg connecting rod 324 is hinged to the footrest bracket 325. The tail of the rear footrest connector 313 is hinged to the head of the first leg connecting rod 323, and the tail of the first leg connecting rod 323 is hinged to the extended footrest plate 321. The two ends of the footrest connector are respectively hinged to the extended footrest plate 321 and the footrest bracket 325. The front footrest connector 312 and the second leg connecting rod 324 are cross-hinged.

[0056] Reference Figure 2 and Figure 3 As shown, the backrest assembly 4 includes a backrest insert 41 and a backrest support 42. The two ends of the backrest support 42 are respectively hinged to the backrest insert 41 and the base 1. The tail end of the backrest insert 41 is a hook-shaped groove that abuts against the anti-rotation pin 43 of the seat frame plate 21. When the backrest insert 41 rotates, the backrest support 42 rotates around the end hinged to the base 1, and the side wall of the groove of the backrest insert 41 abuts against the anti-rotation pin 43 and rotates around the anti-rotation pin 43.

[0057] Example 2:

[0058] Reference Figure 6 A movable sofa includes two extension devices as described in Embodiment 1, which are symmetrically arranged. The bases 1 of the two extension devices are fixed together by a crossbeam 10, and a telescopic drive component 12 is hinged to the crossbeam 10. A linkage beam 11 connects the two footrest assemblies 3, specifically hinged to the front footrest connector 312 of the footrest assembly 3. The output end of the telescopic drive component 12 is hinged to the linkage beam 11. In this embodiment, the telescopic drive component 12 is an electric cylinder, and the extension direction of the electric cylinder is opposite to the opening of the groove 232 of the front linkage rod 23. When adjustment is required, the electric cylinder serves as the power source for adjustment.

[0059] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An extension device comprising a base (1), a seat frame assembly (2), a footrest assembly (3), and a backrest assembly (4), the backrest assembly (4) being connected to the head of the seat frame assembly (2) and the base (1), and the footrest assembly (3) being connected to the tail of the seat frame assembly (2), characterized in that: The seat frame assembly (2) includes a seat frame plate (21), a support rod (22), a front linkage rod (23), and a rear linkage rod (24). The head of the support rod (22) is connected to the base (1) and can rotate relative to the base (1). The tail of the support rod (22) is connected to the foot rest assembly (3). The base (1) is provided with a first fulcrum (5) that restricts the deflection of the tail of the support rod (22). The front linkage rod (23) is hinged between the seat frame plate (21) and the support rod (22). The tail of the base (1) is provided with a second fulcrum (6) that restricts the lifting of the front linkage rod (23). The front linkage rod (23) is hinged to the end of the support rod (22) and extends to provide an abutment portion (24). 1) The abutment part (231) is hook-shaped and forms a groove (232). The abutment part (231) is located on the side wall of the groove (232) and abuts against the second fulcrum (6). The second fulcrum (6) abuts against the abutment part and prevents the front linkage rod (23) from moving upward. The rear linkage rod (24) is hinged between the seat frame plate (21) and the base (1). When the backrest assembly (4) drives the seat frame plate (21) to move laterally relative to the base (1), the seat frame plate (21) drives the front linkage rod (23) to disengage from the lifting restriction of the second fulcrum (6). The rear linkage rod (24) includes a first connecting rod (241) and a second connecting rod (242). The tail of the first connecting rod (241) is hinged. At the base (1), the second connecting rod (242) is hinged between the head of the first connecting rod (241) and the seat frame plate (21). The base (1) is provided with a third fulcrum (7) that limits the lifting of the rear linkage rod (24). The third fulcrum (7) is a first guide groove. The second connecting rod (242) is provided with a first moving part (8) that passes through the first guide groove. The first guide groove includes a first groove body (71) and a second groove body (72) that are connected. The second groove body (72) is located between the first groove body (71) and the backrest assembly (4). The head of the first groove body (71) and the tail of the second groove body (72) form a turning area (73). The tail of the first groove body (71) is located in the turning area (73). Below 3), the first groove (71) has an arc-shaped structure, and the head of the second groove (72) forms an inclined angle towards the backrest assembly (4). The first moving part (8) moves horizontally along the first groove (71) towards the backrest assembly (4). The first moving part (8) is lifted upward from the turning area (73) along the second groove (72). The first fulcrum (5) is the second guide groove. The second guide groove is set vertically in an arc shape and the inclination direction of the arc is the same as the inclination direction of the second groove (72). The support rod (22) is provided with a second moving part (9) that passes through the second guide groove. The rotation of the support rod (22) is restricted by the sliding of the second moving part (9) in the second guide groove.

2. The extension device according to claim 1, characterized in that: The second fulcrum (6) is a rivet structure. The abutting part (231) is provided with an abutting surface (234) on the side wall of the groove (232). The abutting surface (234) is provided with at least two abutting points that fit with the circumferential side of the second fulcrum (6).

3. The extension device according to claim 1, characterized in that: The tail of the support rod (22) is located at the upper end of the second fulcrum (6), and the support rod (22) is provided with a groove (235) that abuts against the second fulcrum (6).

4. The extension device according to claim 1, characterized in that: The footrest assembly (3) includes an input component (31) and a support component (32) that is driven to unfold by the input component (31). A force spring (33) is connected between the input component (31) and the seat frame plate (21). The force spring (33) reaches its maximum elongation during the unfolding process of the footrest assembly (3). The elongation of the force spring (33) in the unfolded state and the elongation of the force spring (33) in the retracted state are both less than the maximum elongation. The rotation direction of the force spring (33) is consistent with the rotation direction of the limiting part.

5. A movable sofa, characterized in that: It includes two extension devices as described in any one of claims 1-4, the two extension devices are arranged symmetrically, and a crossbeam (10) is fixed between the bases (1) of the two extension devices.

6. A movable sofa according to claim 5, characterized in that: A linkage beam (11) is connected between the two foot rest assemblies (3), and a telescopic drive (12) is hinged on the crossbeam (10). The output end of the telescopic drive is hinged to the linkage beam (11).

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