Expandable frame for furniture and sofa with such a

Abstract

An expandable furniture frame comprising a base frame, a seat frame, a backrest device, a footrest device, and a seat frame control assembly, wherein the seat frame is movable relative to the base frame in the forward and backward directions and has at least one initial position, a predetermined intermediate position, and an end position; the backrest device is mounted at the rear end of the seat frame, and the footrest device is mounted at the front end of the seat frame and can switch between a retracted position and an extended position; and the seat frame control assembly is installed between the seat frame and the base frame to control the forward and backward movement of the seat frame relative to the base frame;wherein the extendable furniture frame further comprises a connecting assembly and a backrest control assembly driven by the seat frame, which controls the angle of the backrest device; the seat frame control assembly comprises an outer connecting assembly forming an outer multi-joint connection with the base frame, an inner connecting assembly forming an inner multi-joint connection with the seat frame, and a transmission assembly connecting the outer connecting assembly to the inner connecting assembly; a head end of the connecting assembly is hinged to the footrest device, and a rear end of the connecting assembly is hinged to the inner connecting assembly; the backrest control assembly is hinged to the backrest device, a rear end of the seat frame, and a rear end of the base frame;When changing from the retracted position to the extended position, the footrest device drives the seat frame control assembly via the connecting assembly, thereby moving the seat frame and backrest device together from the home position to the predetermined intermediate position, the forward movement of the seat frame being slower than the extension of the footrest device; and during a process in which the backrest device follows the seat frame from the predetermined intermediate position to the end position, the backrest control assembly adjusts the angle of the backrest device.

Description

FIELD OF UTILITY MODELThe present invention relates to the field of furniture, in particular to an expandable frame for furniture and a sofa with such a frame.BACKGROUND OF THE UTILITY MODELAs the development of the economic and society progress continues, more and more consumer goods are being provided to improve human life, including sofas as a common example.Currently, adjustable armrest floor panels are equipped with an inner, expandable metal frame. This expandable metal frame includes a foot support device, a seat cushion device, and a backrest device. Through a series of mechanical connections, the relative positions and angles of the seat cushion and the seat back can be adjusted so that the sofa can switch between seat, reclining and fully reclined positions to meet the needs of the users.However, in existing expandable metal frames, the foot support device directly drives the backrest device during expansion, thereby tilting the backrest rearward. This rearward tilting takes up space behind the sofa, so that the sofa cannot be placed flush on a wall. If the rear of the sofa is to be placed against a wall, the backrest device may collide with the wall during the foot rest extension process, which fails both the adjustment of the backrest angle and the extension of the foot rest.Moreover, in the footrest devices of the current expandable metal frames, the rear end of the first long link arm is hinged to the lower end of the rear footrest swing arm, and the rear end of the second long link arm is hinged to the lower end of the front footrest swing arm. Both the front and rear foot support pivot arms are hinged at their upper ends to the seat frame, resulting in the foot support device occupying a large amount of vertical space during its extension and retraction process.Therefore, there is an urgent need for an extensible frame for furniture and a sofa equipped with such a frame to solve one or more of these problems.SUMMARY OF THE UTILITY MODELAn object of the present invention is to provide an expandable frame for furniture suitable for zero wall separation applications.Another object of the present invention is to provide a sofa suitable for zero wall separation applications.To achieve the above objects, the present invention provides an expandable frame for furniture, comprising a base frame, a seat frame, a backrest device, a footrest device, a seat frame control assembly, a link assembly, and a backrest control assembly. The seat frame is movable relative to the base frame in a front-rear direction and has at least a home position, a predetermined intermediate position, and an end position. The backrest device is mounted on the rear end of the seat frame and the foot support device is mounted on the front end of the seat frame and is operable to transition between a retracted position and an extended position. The seat frame control assembly is installed between the seat frame and the base frame to control the movement of the seat frame relative to the base frame in the front-rear direction. The control assembly for the seat frame includes an outer link assembly forming a multi-joint outer link and connected to the base frame, an inner link assembly forming a multi-joint inner link and connected to the seat frame, and a transmission assembly connecting the outer link assembly to the inner link assembly. A head end of the link assembly is hinged to the foot support device and an end portion of the link assembly is hinged to the inner link assembly. The seatback control assembly is hinged to the seatback device, the rear end of the seat frame, and the rear end of the base frame. Upon switching from the retracted position to the extended position, the foot support device drives the control assembly for the seat frame via the linkage assembly, whereby the seat frame and the backrest device move together from the initial position to the predetermined intermediate position, wherein the forward movement of the seat frame is slower than the extension of the foot support device. During the process in which the backrest device follows the seat frame from the predetermined intermediate position to the final position, the backrest control assembly adjusts the angle of the backrest device.As compared with the prior art, the head end of the joint assembly of the present invention is hinged to the foot support device, while the end piece of the joint assembly is hinged to the inner joint assembly. In addition, the backrest control assembly is respectively hinged to the rear end of the base frame and the backrest device. During the change from the retracted position to the extended position, the foot support device drives the control assembly for the seat frame via the connection assembly, whereby the seat frame and the backrest device together change from the initial position to the predetermined intermediate position. Once the seat frame and the backrest device have jointly reached the predetermined intermediate position, the backrest control assembly controls the angular adjustment of the backrest device. This allows the adjustment of the angle of the backrest assembly to occur only when the backrest assembly follows the seat frame to the predetermined intermediate position, which provides a spatial clearance for the adjustment of the angle of the backrest assembly and makes the sofa with the expandable frame of the present invention suitable for zero wall distance applications. In addition, the control assembly for the seat frame includes an outer link assembly forming an outer multi-joint link and connected to the base frame, an inner link assembly forming an inner multi-joint link and connected to the seat frame, and a transmission assembly connecting the outer link assembly to the inner link assembly. Thus, the extending foot support device drives the seat frame forward via the linkage assembly, the inner linkage assembly, the transmission assembly, and the outer linkage assembly. As a result, the forward movement of the seat frame is slower compared to the extension of the foot support device when the seat frame and the backrest device change from the initial position to the predetermined intermediate position, which enables an optimum reclining position (TV mode).In order to achieve the above objects, a sofa according to the present invention comprises a backrest, a seat cushion and the above-described extensible frame for furniture. The seat back is mounted to the seat back device, and the seat cushion is mounted to the seat frame.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a plan view of the sofa in the seated position (also referred to as closed mode) according to the present invention, as viewed from right to left, with the protective body on the right side concealed, the foot support device in the retracted position and the seat frame in the initial position. FIG. 2 is a top view of the sofa in the lying position (also referred to as TV mode), viewed from right to left, with the protective body concealed on the right side, the foot support device in the extended position and the seat frame in the predetermined intermediate position. FIG. 3 is a top view of the sofas in a fully reclined position (also referred to as relaxation mode), viewed from right to left, with the protective body hidden on the right, the foot support device in the extended position and the seat frame in the final position. FIG. 4 is a perspective view of the extensible frame for furniture according to the first embodiment of the present invention, with the foot support device in the retracted position and the seat frame in the initial position. FIG. 5 is a plan view of FIG. 4 viewed in the opposite direction of arrow B. FIG. 6 is a top view of FIG. 5, with the seat frame on the right, the control assembly for the seat frame, the link arm, the base frame, the seatback device, the control assembly for the seatback, the extensible drive, and the front fixing rod hidden. FIG. 7 is a perspective view of the extensible frame for furniture according to the first embodiment of the present invention, wherein the foot support device is not yet changed to the extended position and the seat frame is not yet changed to the predetermined intermediate position. FIG. 8 is a plan view of FIG. 7 viewed in the opposite direction of arrow B. FIG. 9 is a plan view of FIG. 8, wherein the seat frame on the right side, the control assembly for the seat frame, the link arm, the base frame, the backrest device, the control assembly for the backrest, the extensible drive, and the front fixing rod are hidden. FIG. 10 is a perspective view of the extensible frame for furniture according to the first embodiment of the present invention, with the foot support device in the extended position and the seat frame in the predetermined intermediate position. FIG. 11 is a plan view of FIG. 10 viewed in the opposite direction of arrow B. FIG. 12 is a plan view of FIG. 11 with the seat frame on the right side, the control assembly for the seat frame, the link arm, the base frame, the backrest device, the control assembly for the backrest, the extensible drive, and the front fixing rod hidden. FIG. 13 is a plan view of FIG. 11 showing the seat frame in a certain intermediate position as it moves toward the end position. FIG. 14 is a plan view of FIG. 13, wherein the seat frame on the right side, the control assembly for the seat frame, the link arm, the base frame, the backrest device, the control assembly for the backrest, the extensible drive, and the front fixing rod are hidden. FIG. 15 is a perspective view of the extensible frame for furniture according to the first embodiment of the present invention with the seat frame in the end position. FIG. 16 is a plan view of FIG. 15 viewed in the opposite direction of arrow B. FIG. 17 is a plan view of FIG. 16 with the seat frame on the right side, the control assembly for the seat frame, the link arm, the base frame, the backrest device, the control assembly for the backrest, the extensible drive, and the front fixing rod hidden. FIG. 18 is a perspective view of FIG. 5 showing the seat frame on the right side, the control assembly for the seat frame, the link arm, the base frame, the seat back device, and the control assembly for the seat back. FIG. 19 is an exploded perspective view of FIG. 18. FIG. 20 is another exploded perspective view of FIG. 19. FIG. 21 is a plan view of the extensible frame for furniture according to the second embodiment of the present invention, with the foot support device in the retracted position and the seat frame in the initial position, with the seat frame on the right side, the control assembly for the seat frame, the connection assembly, the base frame, the backrest device, the control assembly for the backrest, the extensible drive and the front fixing rod hidden. FIG. 22 is a plan view of the extensible frame for furniture according to the second embodiment of the present invention, with the foot support device in the extended position and the seat frame in the end position, with the seat frame on the right side, the control assembly for the seat frame, the connection assembly, the base frame, the backrest device, the control assembly for the backrest, the extensible drive and the front fixing rod hidden. FIG. 23 is a perspective view of FIG. 22. FIG. 24 is an exploded perspective view of FIG. 23. FIG. 25 is another exploded perspective view of FIG. 24.DETAILED DESCRIPTION OF THE INVENTIONEMBODIMENTSFor the detailed explanation of the technical contents and structural features of the present invention, further explanation will be given below in connection with the implementation method and the accompanying drawings.Referring to FIGS. 1 to 3, the sofa 1000 according to the present invention includes an expandable frame 100 for furniture according to a first embodiment, a seat back 200, and a seat cushion 300. The seat back 200 is mounted on a below-described rotatable back frame 70, and the seat cushion 300 is mounted on a below-described seat frame 20. By operating the extensible frame 100 for furniture, the sofa 1000 can switch between a seated position (also referred to as a closed mode) as shown in FIG. 1, a reclining position (also referred to as a TV mode) as shown in FIG. 2, and a fully reclined position (also referred to as a declination mode) as shown in FIG. 3 to meet the needs of the user.As shown in FIGS. 1 to 3, in an embodiment, the sofa 1000 further includes armrests 400 located on both sides of the seat back 200 and the seat cushion 300, footrests 500 mounted on the below-described footrest device 30, and a front support frame 600 disposed below the front lower part of the extensible frame 100 for furniture. The seat back 200 and the seat cushion 300 are located between the two armrests 400. The front support frame 600 is fixedly connected to the armrests 400 on both sides. The extensible frame 100 for furniture is disposed between the armrests 400, and the base frame 10 of the extensible frame 100 for furniture as described below is fixedly connected to the armrests 400. In this way, the armrests 400 provide a mounting location and support for the extensible frame 100 for furniture. It should be noted that although FIGS. 1 to 3 show that the sofa 1000 includes armrests 400, footrests 500, and a front support frame 600, the sofa 1000 of the present invention is not limited to this embodiment. For example, the front support frame 600 may be omitted.Referring to FIGS. 4, 7, and 10, the extensible frame 100 for furniture according to the first embodiment includes a base frame 10, a seat frame 20, a footrest device 30, a seat frame control assembly 40 (see FIGS. 15 and 16 ), a link arm 50, a seat back control assembly 60, and a seat back device 70. the seat frame 20 can move relative to the base frame 10 in the front-rear direction, and has at least a home position (see FIGS. 4 to 6 ), a predetermined intermediate position (see FIGS. 10 to 12 ), and an end position (see FIGS. 10 to 12 ) relative to the base frame 10.The backrest device 70 is mounted on the rear end 21 of the seat frame 20. The rear end 21 of the seat frame 20 provides support and mounting location for the seat back device 70 that moves with the seat frame 20 relative to the base frame 10. The foot support device 30 is mounted to the front end 22 of the seat frame 20, which can transition between a retracted position (see FIGS. 1 and 4-6 ) and an extended position (see FIGS. 2 and 10-12 ) to meet the needs of the user. The foot support device 30 includes a front foot support pivot arm 31 and a rear foot support pivot arm 32 that are each hinged to the seat frame 20. The seat frame control assembly 40 is mounted between the seat frame 20 and the base frame 10 to control movement of the seat frame 20 relative to the base frame 10. The control assembly for the seat frame 40 includes an outer link assembly 41 forming an outer four-bar linkage and connected to the base frame 10, an inner link assembly 42 (see FIG. 10 ) forming an inner four-bar linkage and connected to the seat frame 20, and a transmission assembly 43 (see FIGS. 15 and 16 ) connecting the outer link assembly 41 and the inner link assembly 42 to each other. The inner link assembly 42 includes at least a front inner link arm 421 and a rear inner link arm 423, each of which is hinged to the seat frame 20.More specifically, the head end 50a of the link arm 50 is hinged to the rear foot support swing arm 32, and the tail end 50b of the link arm 50 is hinged to the front inner link arm 421. This configuration connects the foot support device 30 to the inner link assembly 42 that controls the movement of the seat frame 20 and allows the extension and retraction of the foot support device 30 to be faster than the forward and rearward movement of the seat frame 20 relative to the base frame 10.The seat back control assembly 60 is hinged to the seat back device 70, the rear end 11 of the base frame 10, and the rear end 21 of the seat frame 20 and moves together with the seat frame 20.Based on these configurations, during the transition from the retracted position to the extended position, the foot support device 30 drives the control assembly for the seat frame 40 via the link arm 50, whereby the seat frame 20 changes from the initial position (see FIG. 1 ) to the predetermined intermediate position (see FIG. 2 ) together with the backrest device 70. More specifically, the seat frame 20 moves forward more slowly than the extension of the foot support device 30. When the seat back device 70 follows the seat frame 20 from the predetermined intermediate position in FIG. 2 to the final position in FIG. 3, the seat back control assembly 60 controls the seat back device 70 to adjust the angle of the seat back 200 mounted on the seat back device 70. Further, during the change of the seat frame 20 between the initial position and the final position, the head end 50 aof the link arm 50 remains in front of the end piece 50 b, so that the link arm 50 is held at an inclined position as illustrated in FIGS. 5, 8, 11, and 13.It should be noted that, during the switching of the sofa 1000 from the seating position (also referred to as closed mode) to the fully reclined position (also referred to as relaxation mode), when the footrest device 30 switches from the retracted position to the extended position, the link arm 50 drives the control assembly for the seat frame 40 and the seat frame 20 switches from the initial position to the predetermined intermediate position, so that the sofa 1000 is in the reclining position (also referred to as TV mode). When the sofa 1000 is in the reclining position and the seat frame 20 is moved from the predetermined intermediate position to the final position, the backrest control assembly 60 causes the backrest device 70 to move and adjusts the angle of the backrest 200, thereby changing the sofa 1000 from the reclining position to the fully reclined position.More specifically, as shown in FIG. 14, in the left-right direction of the base frame 10, the inner link assembly 42 is disposed on the first side of the seat frame 20 (e.g., the inner side as shown in FIG. 14 ), while the foot support device 30 is disposed on the second side of the seat frame 20 (e.g., the outer side as shown in FIG. 14 ). At this point, the rear foot support pivot arm 32 pivotally connected to the link arm 50 extends from below the seat frame 20 across the first side thereof and upwardly. More specifically, it is shown in FIGS. 5 and 11 that the rear foot support pivot arm 32 is provided with a first pivot point 321 that is hinged to the seat frame 20 and a second pivot point 324 that is hinged to the link arm 50, the first pivot point 321 being located above the second pivot point 324. The front inner link arm 421 has a third pivot point 4213 that is hinged to the seat frame 20 and a fourth pivot point 4214 that is hinged to the link arm 50, wherein the fourth pivot point 4214 is located above the third pivot point 4213 and the third pivot point 4213 is located in front of the first pivot point 321. This allows the link arm 50 to always remain inclined during the movement of the seat frame 20 from the initial position to the final position. In addition, as shown in FIGS. 5, 8, 11, 13 and 16, the link arm 50 remains disposed at an angle relative to the seat frame 20. That is, regardless of whether the sofa 1000 is in the seating position (closed mode), the reclining position (TV mode), or the fully reclined position (relaxation mode), the link arm 50 remains inclined relative to the seat frame 20, as illustrated in FIGS. 5, 8, 11, 13, and 16 in the front-up and rear-down inclined configurations, thereby controlling that the extension of the foot support device 30 is faster than the forward movement of the seat frame 20 relative to the base frame 10.As illustrated in FIGS. 12, 14, 15, and 17 to 20, in an embodiment, the footrest device 30 further includes a front footrest link arm 34, a rear footrest link arm 35, a second intermediate link arm 36, a first long link arm 37, and a second long link arm 38 that extend in the front-rear direction of the base frame 10. Optionally, as illustrated in FIGS. 6 and 14, the first long link arm 37 is longer than the second long link arm 38. the first long link arm 37 and the second long link arm 38 are arranged side by side in the left-right direction of the seat frame 20 such that the first long link arm 37 is interposed between the seat frame 20 and the second long link arm 38 as illustrated in FIG. 15. The upper end of the rear foot support link arm 35 is linked to the rear end 371 of the first long link arm 37, and the lower end of the rear foot support link arm 35 is linked to the rear foot support swing arm 32. The lower end of the front footrest link arm 34 is linked to the front footrest swing arm 31, and the upper end of the front footrest link arm 34 is linked sequentially to the rear end 381 of the second long link arm 38 and the rear end 371 of the first long link arm 37. The second intermediate link arm 36 is hinged to both the rear foot support link arm 35 and the front foot support pivot arm 31, as shown in FIG. 17, such that the second intermediate link arm 36 and the rear foot support link arm 35 together drive the first long link arm 37 at a speed greater than the speed at which the second long link arm 38 is driven by the front foot support link arm 34. This creates a speed difference between the first long link arm 37 and the second long link arm 38.Further, the front end of the first long link arm 37 is hinged to a first foot support head 39a having a support portion 391. The position of the first foot support head 39a remote from the first long link arm 37 is linked to a second foot support head 39b having a support portion 392. The second foot support head 39b is linked with a short arm 39c, and the front end 382 of the second long link arm 38 is linked successively with the first foot support head 39a and the short arm 39c.As shown in Figs. 6, 9, 11-14 and 17, the first foot support head 39a is provided with a first pivot structure 393 pivoted to the front end 372 of the first long link arm 37, a second pivot structure 394 pivoted to the front end 382 of the second long link arm 38, and a third pivot structure 395 pivoted to the second foot support head 39b. The second pivot structure 394 is proximate the first pivot structure 393. The front end 382 of the second long link arm 38 is provided with a fourth pivot structure 383 located forwardly of the second pivot structure 394. The second foot support head 39 bis provided with a fifth pivot structure 396 that is interposed between the third pivot structure 395 and the support portion 392 of the second foot support head 39 b. The short arm 39 cis hinged to both the fourth pivot structure 383 and the fifth pivot structure 396.Optionally, the distance from the second pivot structure 394 to the third pivot structure 395 is D1, the distance from the third pivot structure 395 to the fifth pivot structure 396 is D2, the distance from the fifth pivot structure 396 to the fourth pivot structure 383 is D3, and the distance from the fourth pivot structure 383 to the second pivot structure 394 is D4, wherein the following applies: D1>D3>D4>D2. This arrangement ensures that when the foot support device 30 changes to the retracted position, the support portion 391 of the first foot support head 39 ais oriented forward and the support portion 392 of the second foot support head 39 bis oriented downward. This prevents the first and second foot support heads 39 aand 39 bfrom protruding beyond the seat frame 20 in this position, as shown in FIGS. 1 and 6. When the foot support device 30 shifts to the extended position, the support portion 391 of the first foot support head 39 aand the support portion 392 of the second foot support head 39 bare oriented upward to serve as a foot support, as illustrated in FIGS. 2 and 11. Moreover, by disposing D1>D3>D4>D2, the space required for switching the support portions 391 and 392 between the downward and upward positions is reduced. This ensures that the footrests 500 attached to the support portions 391 and 392 do not collide with the front support frame 600 during the position change.As shown in Figs. 14, 16 and 17 to 20, the front foot support swing arm 31 is provided with a first upper pivot point 311, a first lower pivot point 312, a first intermediate pivot point 315 located between the first upper pivot point 311 and the first lower pivot point 312, and a lowermost pivot point 313 located below the first lower pivot point 312. The lower end of the rear foot support pivot arm 32 is provided with a second intermediate pivot point 322 and a second lower pivot point 323. The seat frame 20 is pivoted at the first upper pivot point 311, while the front foot support link arm 34 is pivoted at the first lower pivot point 312. The first intermediate link arm 33 is pivoted to the first intermediate pivot point 315 and to the second intermediate pivot point 322. In this way, the first intermediate link arm 33, the front foot support link arm 34 and the front foot support swing arm 31 are not coaxially linked. Also, the first intermediate link arm 33, the rear foot support link arm 35 and the rear foot support swing arm 32 are not coaxially linked.In addition, as shown in Figs. 14 and 17 to 20, the rear foot support link arm 35 is provided with a third intermediate pivot point 354 and a third upper pivot point 355 pivoted to the rear end 371 of the first long link arm 37. The second intermediate link arm 36 is pivoted at both the lowermost pivot point 313 and the third intermediate pivot point 354. The third intermediate pivot point 354 is located between the second lower pivot point 323 and the third upper pivot point 355. Optionally, the lower end of the rear foot support link arm 35 may be configured as a curved structure that is curved rearward with the third intermediate pivot point 354 on the curved structure. In this way, the sliding speed of the first long link arm 37 driven by the four-bar linkage of the seat frame 20, the front footrest swing arm 31, the rear footrest swing arm 32, and the first intermediate link arm 33 can be greater than that of the second long link arm 38.Further, as shown in Figs. 14, 17 to 20, the front foot support link arm 34 is provided with a fourth intermediate pivot point 343 and a fourth upper pivot point 344. The rear end 382 of the second long link arm 38 is hinged to the fourth intermediate pivot point 343 of the front foot support link arm 34, while the first long link arm 37 is hinged to the fourth upper pivot point 344 of the front foot support link arm 34. Optionally, the upper end of the front foot support link arm 34 may be configured as a forwardly curved structure with the fourth intermediate pivot point 343 located on the curved structure. In this way, the first long link arm 37 and the second long link arm 38 can closely fit together, and the first long link arm 37 can reliably slide relative to the second long link arm 38 while the footrest device 30 switches between the extended and retracted positions. This allows the support portion 391 of the first foot support head 39 ato rotate between the forward and upward positions.Referring to FIGS. 6, 9 and 12, the operating principle of the foot support device 30 will be explained. When the foot support device 30 is changed from the retracted position as shown in FIG. 6 to the extended position as shown in FIG. 12, the front foot support pivot arm 31 rotates counterclockwise about the first upper pivot point 311, and the rear foot support pivot arm 32 rotates counterclockwise about the first pivot point 321. This moves the first intermediate link arm 33 upward while simultaneously the front foot support link arm 34 swings clockwise about the first lower pivot point 312 and the rear foot support link arm 35 swings clockwise about the second lower pivot point 323. The second intermediate link arm 36 also rotates clockwise. Thereby, the first long link arm 37 and the second long link arm 38 slide forward, and the sliding speed of the first long link arm 37 is greater than that of the second long link arm 38. When the front foot support swing arm 31 is rotated counterclockwise about the first upper pivot point 311 and the rear foot support swing arm 32 is rotated counterclockwise about the first pivot point 321 to the position of FIG. 12, the support portions 391 and 392 of the first and second foot support heads 39 aand 39 bare precisely at the upward position as illustrated in FIG. 12. It should be noted that Fig. 9 shows an intermediate position during the transition from the retracted to the extended position. The process of changing the foot support device 30 from the extended position back to the retracted position is exactly the reverse and will not be described further herein. It is found that by these configurations of the foot support device 30, space utilization in the vertical direction of the seat frame 20 is minimized.As shown in FIGS. 17 to 20, the inner link assembly 42 further includes an inner intermediate link arm 422 extending in the front-rear direction of the base frame 10 and disposed below the seat frame 20. The inner intermediate link arm 422 is hinged to both the front inner link arm 421 and the rear inner link arm 423. Thereby, the inner link arm 422 allows the front inner link arm 421 to move the seat frame 20 forward by pulling the inner link arm 422 and the rear inner link arm 423.As shown, the outer link assembly 41 includes a front outer link arm 411, an outer intermediate link arm 412, and a rear outer link arm 413. The outer intermediate link arm 412 extends along the front-rear direction of the base frame 10 and is located above the base frame 10. The transmission assembly 43 includes a front transmission arm 431, an intermediate transmission arm 432, and a rear transmission arm 433. The front transmission arm 431 is linked to both the inner intermediate link arm 422 and the front outer link arm 411. The rear transmission arm 433 is hinged to both the rear outer link arm 413 and the inner intermediate link arm 422. The intermediate transmission arm 432 is hinged to both the central portion of the outer intermediate connection arm 412 and the rear transmission arm 433. Thus, the inner link assembly 42 forming an inner four-bar linkage with the seat frame 20 and the outer link assembly 41 forming an outer four-bar linkage with the base frame 10 are connected to each other through the front transmission arm 431, the intermediate transmission arm 432 and the rear transmission arm 433, thereby ensuring the sequential movement of the inner and outer link assemblies 42 and 41. Specifically, as shown in FIGS. 19 and 20 as an example, the front outer link arm 411 has a pivot point 4111 that is linked to the front transmission arm 431, the outer intermediate link arm 412 has a pivot point 4121 that is linked to the intermediate transmission arm 432, and the rear outer link arm 413 has a pivot point 4131 that is linked to the rear transmission arm 433, as shown in FIGS. 19 and 20.As shown in FIGS. 4 to 20, in one embodiment, the seat back device 70 includes a back back back rear swing arm 71, a back back front swing arm 72, and a rotatable back frame 73 that enables the seat back 200 to be mounted and the angle thereof to be adjusted by rotation. The rear seat back swing arm 71 has a first pivot point 711 hinged to the rear end 21 of the seat frame 20, a second pivot point 712 hinged to the rotatable back frame 73, and a third pivot point 713 hinged to the end portion of the second control link arm 63. The third pivot point 713 is positioned below the second pivot point 712, as shown in FIGS. 5 and 6. The front seat back swing arm 72 has a fourth pivot point 721 pivoted to the rear end 21 of the seat frame 20 and a fifth pivot point 722 pivoted to the rotatable back frame 73. The fifth pivot point 722 is located above the fourth pivot point 721 and before the second pivot point 712, while the fourth pivot point 721 is positioned before the first pivot point 711. Optionally, the distances from the second pivot point 712 to the first pivot point 711 are P 5, from the fourth pivot point 721 to the fifth pivot point 722 are P 6, from the first pivot point 711 to the fourth pivot point 721 are P 7, and from the second pivot point 712 to the fifth pivot point 722 are P 8, wherein P 7>P 5>P 6>P 8. In this way, the arrangement of the seat frame 20, the rear seat back swing arm 71, the front seat back swing arm 72, and the rotatable back frame 73 forms a trapezoidal four-bar linkage that allows the rotatable back frame 73 to rotate at a greater angle under the drive of the rear seat back swing arm 71.As shown in FIGS. 4 to 8, 10, 11, 13, 15, and 16, in one embodiment, the control assembly for the seat back 60 includes a first control swing arm 61, a first control link arm 62, and a second control link arm 63. The upper end of the first control swing arm 61 is linked to the lower end of the first control link arm 62 to form a second pivot axis C 2. The upper end of the first control link arm 62 is linked to the front end of the second control link arm 63 to form a third pivot axis C 3. The first control link arm 62 is further hinged to the rear end 21 of the seat frame 20 to form a fourth pivot axis C 4. The rear end of the second control link arm 63 is hinged to the backrest device 70 (in particular, the third pivot point 713).In this way, the seatback control assembly 60 pivotally drives the rear seatback pivot arm 71 when the seat frame 20 and the seatback device 70 move relative to the base frame 10 to the predetermined intermediate position, as shown in FIG. 11. Moreover, as shown in FIGS. 1 to 3, during the adjustment process, the seat back 200 mounted on the rotatable back frame 73 rotates about almost the same axis relative to the seat pad 300 mounted on the seat frame 20, thereby preventing the user's clothes from stretching.As illustrated in FIG. 5, the distance from the first pivot axis C 1 to the second pivot axis C 2 P 1, the distance from the second pivot axis C 2 to the fourth pivot axis C 4 P 2, the distance from the fourth pivot axis C 4 to the third pivot axis C 3 P 3, and the distance from the third pivot axis C 3 to the third pivot point 713 P 4. Moreover, P2>P1>P7>P5>P6>P8>P3>P4. This arrangement ensures that the backrest control assembly 60 effectively controls the backrest device 70 such that the angular adjustment of the backrest 200 occurs only when the seat frame 20 and the backrest device 70 jointly reach the predetermined intermediate position.In addition, as illustrated in FIGS. 5, 8, and 11, in one embodiment, the control assembly for the seat back 60 further includes a second control swing arm 64 located rearward of the first control swing arm 61 and a middle control link arm 65 extending in the front-rear direction of the base frame 10. The lower end of the second control swing arm 64 is hinged to the rear end 11 of the base frame 10 to form a fifth swing axis C 5. The upper end of the second control swing arm 64 is linked to the intermediate control link arm 65 to form a sixth pivot axis C 6. The intermediate control link arm 65 is linked to the upper end of the first control swing arm 61 to form a seventh swing axis C 7 located rearward of the second swing axis C 2. In addition, at a position of the center control link arm 65 located rearward of the sixth pivot axis C 6, a rear fixing rod 90 bextending in the left-right direction of the base frame 10 is attached. With this four-bar mechanism consisting of the first control swing arm 61, the second control swing arm 64, the intermediate control link arm 65, and the base frame 10, the rear position of the rear fixing rod 90b relative to the rear end 11 of the base frame 10 is shortened. This allows for more design possibilities for the sofa 1000. Moreover, this configuration reduces the minimum installation distance of the telescopic drive 80, thereby achieving a shorter stroke of the telescopic drive 80, enabling a faster expansion of the extensible frame 100 for furniture in the first embodiment, even at a limited speed of the drive.As shown in FIGS. 4, 7, 10, and 15, the furniture extensible frame 100 in the first embodiment further includes a telescopic driver 80 and a spring 90 a. The telescopic drive 80 includes a drive body 81 and a telescopic body 82 that slides telescopically on the drive body 81. A front fixing rod 90c extending in the left-right direction of the base frame 10 is fixedly connected to the front footrest swing arm 31 as shown in FIGS. 4, 7, 10 and 15. Obviously, the front fixing rod 90c could also be fixed to the rear foot support swing arm 32 if necessary, which is not limited to the arrangement shown in Figs. 4, 7, 10 and 15. The driving body 81 is hinged to the rear fixing rod 90b, and the telescopic body 82 is hinged to the front fixing rod 90c. Obviously, if necessary, the driving body 81 could be hinged to the front fixing rod 90c and the telescopic body 82 could be hinged to the rear fixing rod 90b, which is not limited to the arrangement shown in Figures 4, 7, 10 and 15. The spring 90a is connected to both the rear fixing rod 90b and the inner link assembly 42 (more specifically, the inner intermediate link arm 422). With the assistance of spring 90a and telescopic drive 80, spring 90a is in the compressed state as foot support device 30 expands, thereby providing additional force to telescopic drive 80 allowing it to expand foot support device 30 with less force. In addition, the support of the spring 90a and the telescopic drive 80 reduces the number of drives 80 required. It should be noted that the telescopic drive 80 could be, but is not limited to, an electric push rod. Moreover, as shown in FIGS. 4, 7, 9, 10, 12 and 15, the rear end of the inner link arm 422 is provided with a pin 4221 to install the front end of the spring 90 a.As illustrated in FIGS. 4, 7, 10, and 15, each of the assemblies including the base frame 10, the seat frame 20, the seat back device 70, the seat back control assembly 60, the foot support device 30, the link arm 50, and the seat frame control assembly 40 is arranged in pairs, each pair being respectively positioned in the left-right direction of the base frame 10. The left and right ends of the rear fixing rod 90b are respectively fixedly connected to the same end center control link arm 65, and the left and right ends of the front fixing rod 90c are respectively fixedly connected to the same end front foot support swing arm 31, more specifically, at the fixing position 314 of the front foot support swing arm 31, Since the front fixing rod 90c is fixedly connected to the front foot support swing arm 31, the telescopic driver 80 can expand the foot support device 30 more easily.Referring to the accompanying drawings, the process of moving the sofa 1000 of the present utility application from a seated position (closed mode) to a fully reclined position (relaxation mode) will be explained. When the sofa 1000 in the seat position in FIG. 1 is to be adjusted to the reclining position (TV mode) in FIG. 2, the telescopic drive 80 is activated. Accordingly, the telescopic drive 80 drives the foot support device 30 to expand forward. As a result, the extending footrest device 30 causes the seat frame 20 to move forward relative to the base frame 10 through the link arm 50 and the control assembly for the seat frame 40. Because the control assembly for the seat back 60 is hinged to the rear end 21 of the seat frame 20, the rear end 11 of the base frame 10, and the seat back device 70, the forward movement of the seat frame 20 causes the second control link arm 63, the middle control link arm 65, and the first control swing arm 61 to pivot clockwise downward while the first control link arm 62 pivots counterclockwise downward as shown in FIGS. 5 and 8. Further, the spring 90a is maintained in the compressed state as the foot support device 30 expands, thereby applying additional force to the telescopic actuator 80 so that it can more easily expand the foot support device 30 with less force.When the telescopic drive 80 extends the foot support device 30 fully forward, as shown in FIG. 2, the telescopic body 82 of the drive 80 moves further forward, so that the seat frame 20 and the seat back device 70 also move forward. Under the control of the control assembly for the seat back 60, as shown in FIGS. 11, 13, and 16, the second control link arm 63, the middle control link arm 65, the first control swing arm 64, and the first control link arm 61 swing downward in the clockwise direction, while the first control link arm 62 swing downward in the counterclockwise direction, thereby adjusting the angle of the rotatable back frame 73, as shown in FIGS. 3 and 16. As the seat frame 20 moves from the predetermined intermediate position in FIG. 2 to the end position in FIG. 3, the spring 90 ais expanded.In the extensible frame 100 for furniture of the first embodiment, the link arm 50 is hinged at its rear end 50b to the inner link arm 421 and hinged at its front end 50a to the rear foot support swing arm 32. During the transition from the retracted position to the extended position, the foot support device 30 drives the control assembly for the seat frame 40 via the link arm 50 and causes the seat frame 20 and the backrest device 70 to change together from the initial position to the predetermined intermediate position. Moreover, during movement of the seat frame 20 between the initial position and the final position, the front end 50 aof the link arm 50 always remains in front of the rear end 50 b,so that the link arm 50 is maintained in an inclined position and a push-pull arrangement is avoided. This ensures stable movement of the seat frame 20, which improves user experience. During the transition from the retracted position to the extended position, the foot support device 30 drives the control assembly for the seat frame 40 via the link arm 50, whereby the seat frame 20 together with the backrest device 70 changes from the initial position to the predetermined intermediate position. When the seat frame 20 and the seat back device 70 reach the predetermined intermediate position, the seat back control assembly 60 controls the seat back device 70 for angle adjustment. In this manner, the angular adjustment of the seat back device 70 is only performed when the seat back device 70 follows the seat frame 20 to the predetermined intermediate position, which provides a space for the angular adjustment of the seat back device 70 and makes the sofa 1000 of the present utility model suitable for zero-distance wall applications.As shown in Figs. 21 to 25, the extensible frame 100' for furniture according to the second embodiment is structurally similar to the extensible frame 100 for furniture according to the first embodiment, but has the following differences,The link assembly 50' in the second embodiment includes a first link arm 51, a second link arm 52, and a third link arm 53 that are located below the seat frame 20 and extend along the base frame 10 in the front-rear direction. In contrast, in the first embodiment, the linkage assembly includes only the link arm 50.In the second embodiment, the first link arm 51 constitutes the front end of the link assembly 50', i.e. the number 51 also represents the front end of the link assembly 50'. One end of the first link arm 51 is pivoted to the side pivot point 322' of the rear foot support swing arm 32, while the other end thereof is pivoted to one end of the second link arm 53 to form a first pivot point 54. The other end of the second link arm 53 is pivoted to the rear end of the third link arm 52 to form a second pivot point 55. In addition, the second link arm 53 is pivoted at an intermediate position with the seat frame 20 to form a third pivot point 56, thereby providing a four-bar linkage with the seat frame 20, the rear foot support pivot arm 32, the first link arm 51 and the second link arm 53. The forward end of the third link arm 52 is pivotally connected to the forward inner link arm 421 at its pivot point 4212. The third link arm 52 forms the rear end of the link assembly 50', i.e. the number 52 also represents the rear end of the link assembly 50'. Specifically, as shown in FIG. 22, the rear end of the third link arm 52 is an upwardly inclined end 521 configured to smoothly and reliably press the front inner link arm 421.While in the first embodiment, the head end 50a of the link arm 50 is hinged to the rear footrest swing arm 32 and the rear end 50b of the link arm 50 is hinged to the front inner link arm 421. More specifically, the head end 50a of the link arm 50 is pivoted to the second pivot point 324 of the rear foot support swing arm 32, and the rear end 50b of the link arm 50 is pivoted to the fourth pivot point 4214 of the front inner link arm 421, as shown in FIG. 11.Second, in the second embodiment, an arc-shaped long hole 373 is provided at the rear end 371 of the first long link arm 37, and a restricting protrusion 353 located inside the arc-shaped long hole 373 is provided at the rear foot support link arm 35. When the foot support device 30 is placed in the retracted position, the restricting protrusion 353 abuts against the hole wall 3731 at one end of the arc-shaped long hole 373 as shown in FIG. 21. When the foot support device 30 is placed in the extended position, the restricting protrusion 353 abuts against the hole wall 3731 at the other end of the arc-shaped long hole 373 as shown in FIG. 22. The purpose of this configuration is to effectively prevent the foot support device 30 from being excessively extended or retracted.While in the first embodiment, the arc-shaped long hole 373 is provided at the rear end 371 of the first long link arm 37, but no restricting protrusion 353 is provided at the rear foot support link arm 35.Third, in the second embodiment, the rear foot support pivot arm 32 is provided with a second upper pivot point 321' hinged to the seat frame 20, a lateral pivot point 322' located adjacent the second upper pivot point 321', and a second lower pivot point 323. While in the first embodiment the rear foot support pivot arm 32 is provided with a first pivot point 321, a second intermediate pivot point 322, a second lower pivot point 323, and a second pivot point 324 that is hinged to the link arm 50.Fourth, in the second embodiment, no intermediate front pivot point 315 is provided on the front foot support swing arm 32. While in the first embodiment the intermediate front pivot point 315 is present on the front foot support pivot arm 32.Fifthly, in the second embodiment, the front end of the first intermediate link arm 33 is hinged at the lowermost pivot point 313, and the rear end of the first intermediate link arm 33 is hinged at the second lower pivot point 323. While in the first embodiment, the front end of the first intermediate link arm 33 is hinged to the front intermediate pivot point 315 and the rear end of the first intermediate link arm 33 is hinged to the second intermediate pivot point 322, as shown in FIG. 13.Sixth, in the second embodiment, the upper end of the front inner link arm 421 is provided with a pivot point 4211 hinged to the seat frame 20, and the central portion of the front inner link arm 421 is provided with a pivot point 4212 hinged to the rear end 52 of the link arm 50. The upper end of the rear inner link arm 423 is provided with a pivot point 4231 pivoted to the seat frame 20 as shown in Figs. 24 and 25. While in the first embodiment the front inner link arm 421 is provided with a third pivot point 4213 which is hinged to the seat frame 20.Seventh, in the second embodiment, the front end of the inner link arm 422 is provided with a pivot point 4222 hinged to the front transmission arm 431, and the rear end of the inner link arm 422 is provided with a pivot point 4221 hinged to the rear transmission arm 433.Other structures are the same except for the differences mentioned above, and will not be described again here.Compared with the prior art, in the link assembly of the present invention, the head end is hinged to the foot support device 30 and the rear end to the inner link assembly 42. During the transition from the retracted position to the extended position, the foot support device 30 drives the control assembly for the seat frame 40 via the linkage assembly 50, whereby the seat frame 20 and the backrest device 70 together change from the initial position to the predetermined intermediate position. When the seat frame 20 and the seat back device 70 together change to the predetermined intermediate position, the seat back control assembly 60 controls the seat back device 70 for angle adjustment. In this manner, the angular adjustment of the seatback device 70 is only performed when the seatback device 70 follows the seat frame 20 to the predetermined intermediate position, thereby providing space for the angular adjustment of the seatback device 70, and the sofa 1000 having the extensible frame 100 ( 100') of the present invention is suitable for wall-zero-distance applications.Moreover, the control assembly for the seat frame 40 includes an outer link assembly 41 that forms an outer multi-joint connection with the base frame 10, an inner link assembly 42 that forms an inner multi-joint connection with the seat frame 20, and a transmission assembly 43 that connects the outer link assembly 41 to the inner link assembly 42. Thus, the extending footrest device 30 propels the seat frame 20 through the linkage assembly, the inner linkage assembly 42, the transfer assembly 43, and the outer linkage assembly 41. As a result, during the transition of the seat frame 20 and the seat back device 70 from the initial position to the predetermined intermediate position, the forward movement of the seat frame 20 is slower than the extension of the foot support device 30, causing a slight change in the position of the seat frame 20 relative to the base frame 10 and enabling a preferred reclining position (TV mode).It is important to note that the term "zero distance to the wall" refers to the seat back 200 of the sofa 1000 being able to be positioned directly on the wall without any distance therebetween. As shown in FIGS. 1-3, the vertical centerline represents the position of the wall, and when the sofa 1000 is in the seating position, the distance between the backrest 200 of the sofa 1000 and the vertical centerline is zero. When the sofa 1000 switches from the seating position to the reclining position and to the fully reclined position, the distance between the seat back 200 and the vertical centerline increases, thereby preventing any interference between the seat back 200 and the vertical centerline during the adjustment of the seat back 200.Note that the direction indicated by the arrow A in the drawings is from the rear to the front of the base frame 10, the direction indicated by the arrow B is from left to right of the base frame 10, and the direction indicated by the arrow C is from bottom to top of the base frame 10. Moreover, while the inner link assembly 42 forms an inner four-bar linkage with the seat frame 20, it may also form an inner five-bar linkage, if desired. Likewise, while the outer link assembly 41 forms an outer four-bar linkage with the base frame 10, it may also form an inner five-bar linkage structure, if desired.The above disclosure is only preferred embodiments of the present invention and cannot be used to limit the scope of the present invention. Therefore, all equivalent modifications made in accordance with the claims of the present invention are intended to be included within the scope of the present invention.

Claims

An expandable frame for furniture comprising a base frame, a seat frame, a backrest device, a foot support device and a control assembly for the seat frame, wherein the seat frame is movable relative to the base frame in front and rear directions and has at least a starting position, a predetermined intermediate position and an end position; the backrest device is mounted at the rear end of the seat frame and the foot support device is mounted at the front end of the seat frame and is capable of switching between a retracted position and an extended position; and the control assembly for the seat frame is installed between the seat frame and the base frame to control the forward and rearward movement of the seat frame relative to the base frame; wherein the expandable frame for furniture further comprises a linkage assembly and a seat frame driven seat back control assembly that controls the angle of the seat back device, the seat frame control assembly comprises an outer linkage assembly that forms an outer multi-jointed connection with the base frame, an inner linkage assembly that forms an inner multi-jointed connection with the seat frame, and a transmission assembly that connects the outer linkage assembly with the inner linkage assembly; a head end of the linkage assembly is linked to the footrest device and a rear end of the linkage assembly is linked to the inner linkage assembly; the seat back control assembly is linked to the seat back device, a rear end of the seat frame, and a rear end of the base frame; Upon changing from the retracted position to the extended position, the foot support device drives the seat frame control assembly via the linkage assembly, whereby the seat frame and the backrest device are moved together from the initial position to the predetermined intermediate position, wherein the forward movement of the seat frame is slower than the extension of the foot support device; and during a process in which the backrest device follows the seat frame from the predetermined intermediate position to the final position, the backrest control assembly adjusts the angle of the backrest device.The extensible frame for furniture of claim 1, wherein the foot support device comprises at least one foot support pivot arm hinged to the seat frame and the inner link assembly comprises at least one inner link arm hinged to the seat frame; the head end of the link assembly is hinged to the foot support pivot arm and the rear end of the link assembly is hinged to the inner link arm.The extensible frame for furniture of claim 2, wherein the linkage assembly comprises a link arm whose head end is hinged to the foot support pivot arm and whose rear end is hinged to the inner link arm; during a process in which the seat frame is changed from the home position to the final position, the head end of the link arm always remains forward of the rear end of the link arm.The expandable frame for furniture of claim 3, wherein in a left-right direction of the base frame, the inner link assembly is disposed on a first side of the seat frame while the foot support device is disposed on an opposite second side of the seat frame; the foot support pivot arm hinged to the link arm extends below the seat frame to the first side of the seat frame and then upwardly; and the link arm is disposed at an inclined angle relative to the seat frame.The extensible frame for furniture of claim 4, wherein the foot support pivot arm is provided with a first pivot point hinged to the seat frame and a second pivot point hinged to the link arm, the first pivot point being positioned above the second pivot point; the inner link arm is provided with a third pivot point hinged to the seat frame and a fourth pivot point hinged to the link arm, the fourth pivot point being positioned above the third pivot point; and the third pivot point being positioned before the first pivot point.The extensible frame for furniture according to claim 3, wherein the inner link assembly further comprises an inner intermediate link arm extending in the front-rear direction of the base frame and disposed below the seat frame; the inner link arm comprises a front inner link arm and a rear inner link arm each hinged to the inner intermediate link arm; the rear end of the link arm is hinged to the front inner link arm; and the outer multi-hinge link is a four-hinge link.The extensible frame for furniture of claim 3, wherein the foot support device further comprises a first intermediate link arm located below the seat frame and extending in the front-rear direction of the base frame; the foot support swing arm comprises a front foot support swing arm hinged to a front end of the first intermediate link arm and a rear foot support swing arm hinged to a rear end of the first intermediate link arm; and the head end of the link assembly is hinged to the rear foot support swing arm.The extensible frame for furniture according to claim 7, wherein the foot support device further comprises a front foot support link arm, a rear foot support link arm, a second intermediate link arm, a first long link arm and a second long link arm extending in the front-rear direction along the base frame; an upper end of the rear foot support link arm is hinged to a rear end of the first long link arm, and a lower end of the rear foot support link arm is hinged to the rear foot support swing arm; a lower end of the front foot support link arm is hinged to the front foot support swing arm, and an upper end of the front foot support link arm is sequentially hinged to a rear end of the second long link arm and a rear end of the first long link arm; the second intermediate link arm is hinged to each of the rear foot support link arm and the front foot support swing arm; a front end of the first long link arm is hinged to a first foot support head having a support portion, and a position of the first foot support head remote from the first long link arm is hinged to a second foot support head having a support portion; the second foot support head is hinged to a short arm, and a front end of the second long link arm is sequentially hinged to the first foot support head and the short arm; when the foot support device is switched to the retracted position, the support portions of each of the first and second foot support heads are arranged in a front and downward configuration, and the first and second long link arms are retracted into the seat frame; when the foot support device is switched to the extended position, the support portions of both the first and second foot support heads are disposed upwardly, and the first and second long link arms slide and extend beyond the seat frame.The extensible frame for furniture of claim 8, wherein the front foot support pivot arm is provided with a first upper pivot point, a first lower pivot point, a first intermediate pivot point between the first upper pivot point and the first lower pivot point, and a lowermost pivot point located adjacent the first lower pivot point; the seat frame is hinged to the first upper pivot point, the front foot support link arm is hinged to the first lower pivot point, and the first intermediate link arm is hinged to the first intermediate pivot point; the rear foot support pivot arm is sequentially provided with a second intermediate pivot point and a second lower pivot point; the rear foot support link arm is hinged to the second lower pivot point, and the first intermediate link arm is hinged to the second intermediate pivot point; the rear foot support link arm is provided with a third intermediate pivot point and a third upper pivot point connected to the rear end of the first long link arm; the second intermediate link arm is hinged to both the lowermost pivot point and the third intermediate pivot point, the third intermediate pivot point being positioned between the second lower pivot point and the third upper pivot point; the front foot support link arm is further provided with a fourth intermediate pivot point and a fourth upper pivot point, the rear end of the second long link arm being hinged to the fourth intermediate pivot point, and the first long link arm being hinged to the fourth upper pivot point.The extensible frame for furniture of claim 2, wherein the control assembly for the backrest comprises a first control pivot arm, a first control link arm, and a second control link arm, a lower end of the first control pivot arm is hinged to the rear end of the base frame to form a first pivot axis, and an upper end of the first control pivot arm is hinged to a lower end of the first control link arm to form a second pivot axis; an upper end of the first control link arm is hinged to a head end of the second control link arm to form a third pivot axis; the first control link arm is further hinged to the rear end of the seat frame to form a fourth pivot axis, and a rear end of the second control link arm is hinged to the backrest device.The extensible frame for furniture according to claim 10, further comprising a telescopic actuator and a spring, wherein the telescopic actuator comprises an actuator body and a telescopic body telescopically slides on the actuator body, the control assembly for the backrest further comprises a second control swing arm disposed behind the first control swing arm, and an intermediate control link arm extending in the front-rear direction along the base frame, a lower end of the second control swing arm is hinged to the rear end of the base frame to form a fifth pivot axis, and an upper end of the second control swing arm is hinged to the intermediate control link arm to form a sixth pivot axis; the intermediate control link arm is hinged to the upper end of the first control swing arm to form a seventh pivot axis located rearward of the second pivot axis; a position on the intermediate control link arm rearward of the sixth pivot axis is connected to a rear fixing rod extending in the left-right direction of the base frame, and the foot support swing arm is connected to a front fixing rod extending in the left-right direction of the base frame; one of the driving body and the telescopic body is hinged to the rear fixing rod, and the other of the driving body and the telescopic body is hinged to the front fixing rod; and the spring is fixed to both the rear fixing rod and the inner link assembly.The extensible frame for furniture of claim 10, wherein the backrest device comprises a backrest rear pivot arm, a backrest front pivot arm and a backrest rotatable frame that adjusts the angle of the backrest, the backrest rear pivot arm being provided with a first pivot point hinged to the rear end of the seat frame, a second pivot point hinged to the backrest rotatable frame, and a third pivot point hinged to the rear end of the second control link arm, the third pivot point being located below the second pivot point; the front seat back swing arm is provided with a fourth pivot point hinged to the rear end of the seat frame and a fifth pivot point hinged to the rotatable frame for the seat back, the fifth pivot point being positioned above the fourth pivot point and in front of the second pivot point, while the fourth pivot point is positioned in front of the first pivot point; wherein a distance from the first pivot axis to the second pivot axis is P 1, a distance from the second pivot axis to the fourth pivot axis is P 2, a distance from the fourth pivot axis to the third pivot axis is P 3, a distance from the third pivot axis to the third pivot point is P 4, a distance from the second pivot point to the first pivot point is P 5, a distance from the fourth pivot point to the fifth pivot point is P 6, a distance from the first pivot point to the fourth pivot point is P 7 and a distance from the second pivot point to the fifth pivot point is P 8, and P 2>P 1>P 7>P 5>P 6>P 8>P 3>P 4.The extensible frame for furniture of claim 2, wherein the foot support device further comprises a first intermediate link arm located below the seat frame and extending in the front-rear direction of the base frame, the foot support swing arm comprises a front foot support swing arm hinged to a front end of the first intermediate link arm and a rear foot support swing arm hinged to a rear end of the first intermediate link arm; the inner link assembly further comprises an inner intermediate link arm extending in the front-rear direction of the base frame and disposed below the seat frame; the inner link arm comprises a front inner link arm and a rear inner link arm each hinged to the inner intermediate link arm; the head end of the link assembly is hinged to the front foot support pivot arm and the rear foot support pivot arm, and the rear end of the link assembly is hinged to the front inner link arm.The extensible frame for furniture of claim 13, wherein the linkage assembly comprises a first link arm, a second link arm, and a third link arm positioned below the seat frame and extending in the front-rear direction along the base frame, the rear foot support pivot arm is provided with a second upper pivot point hinged to the seat frame, a lateral pivot point disposed on a front side of the second upper pivot point, and a second lower pivot point hinged to the rear end of the first intermediate link arm; the first link arm forms the head end of the link assembly, one end of the first link arm is hinged at the lateral pivot point and the other end of the first link arm is hinged at one end of the second link arm, the other end of the second link arm is hinged at a rear end of the third link arm, and the second link arm is further hinged at the seat frame, thereby forming a four-bar linkage with the seat frame, the rear foot support swing arm, the first link arm, and the second link arm; and a front end of the third link arm is hinged at the front inner link arm, the third link arm forms the rear end of the link assembly, a rear end of the third link arm is an upwardly inclined end, and the outer multi-bar linkage is a four-bar linkage.A sofa comprising a backrest, a seat cushion and the extensible frame for furniture according to any one of claims 1 to 14, wherein the backrest is mounted on the backrest device and the seat cushion is mounted on the seat frame.

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