Mechanical extension device for a movable seat unit and seat unit

Abstract

The utility model relates to a mechanical stretching device for a movable seat unit. The mechanical stretching device comprises a base assembly; a side panel for attaching a seat portion of the seat unit; the backrest assembly comprises a backrest mounting piece and a backrest connecting rod assembly; and a central linkage member; wherein the backrest connecting rod assembly comprises a first backrest connecting rod and a second backrest connecting rod, the upper end part of the first backrest connecting rod is hinged with the front end of the backrest mounting piece at a first pivot point, the front end part of the second backrest connecting rod is hinged with the side plate at a second pivot point, and the middle part of the second backrest connecting rod is hinged with the middle part of the first backrest connecting rod; a leg stretching device; the mechanical stretching device enables the seat unit to be converted between at least a sitting position and a lying position, and compared with the sitting position, the distance between the first pivot point and the second pivot point is reduced in the lying position. In addition, the utility model further relates to a movable seat unit.

Description

Technical Field

[0001] The utility model relates to a mechanical extension device for a movable seat unit and a seat unit comprising the mechanical extension device. Background Art

[0002] In the prior art, a variety of movable seat units are known, such as sofas or seats with multi-position conversion functions. As people's living standards improve, the comfort requirements for sofas and seats are also increasing. In known designs, movable seat units are usually equipped with a mechanical extension device, which can be transformed between a sitting position, a TV position (or a leisure position) and a lying position. When the seat unit is transformed from a sitting position to a TV position, the footrest of the seat unit extends forward, and the angle between the backrest and the seat portion remains basically unchanged. When the seat unit is transformed from a leisure position to a lying position, the footrest is further forward and upward than the leisure position, and the backrest is significantly tilted back, so that the legs of the user of the seat unit are higher than the head when in a lying position, and the user experiences the so-called "zero gravity" feeling.

[0003] However, a disadvantage of the known design is that, as the seat unit is transformed into a lying position, a gap appears between the backrest and the seat, which on the one hand pulls the user's top upwards and on the other hand causes the risk of objects falling through the gap. Utility Model Content

[0004] The technical problem to be solved by the utility model is to provide a seat unit with a simple structure and better conformity to ergonomics.

[0005] In order to solve the above technical problems, the utility model provides a mechanical extension device for a movable seat unit, comprising:

[0006] - A base assembly fixedly supported on the ground;

[0007] - a side panel movably supported above the base assembly for attaching a seat portion of a seating unit;

[0008] - a backrest assembly pivotally connected to the rear portion of the side panel, comprising a backrest mounting member and a backrest link assembly; and

[0009] - a central linkage, which is movably connected between the side panels and the backrest assembly;

[0010] The backrest link assembly includes a first backrest link and a second backrest link, the upper end of the first backrest link is hinged to the front end of the backrest mounting member at a first pivot point, the front end of the second backrest link is hinged to the side plate at a second pivot point, and the middle portion of the second backrest link is hinged to the middle portion of the first backrest link;

[0011] - a leg extension device pivotally connected to the front of the side panel, comprising a plurality of links pivotally connected to each other, a first footrest for attaching a footstool;

[0012] The mechanical extension device enables the seat unit to be transformed at least between a sitting position and a lying position, in which the first footrest is folded under the seat part; in the lying position, the backrest is tilted backward and the first footrest is forward and extended compared to the sitting position, and wherein the distance between the first pivot point and the second pivot point is reduced in the lying position compared to the sitting position.

[0013] In this embodiment, preferably, the backrest link assembly is compressed and expanded by the relative movement of the central link rod and the side plate, thereby realizing the rearward and forward rotation of the backrest mounting member around the first pivot point.

[0014] According to a preferred embodiment, the backrest link assembly also includes a third backrest link, wherein the lower end of the first backrest link is hinged to the central link at a third pivot point, the upper end of the third backrest link is hinged to the rear end of the backrest mounting member, and the lower end of the third backrest link is hinged to the rear end of the second backrest link.

[0015] According to a preferred embodiment, during the transformation of the seat unit from a sitting position to a lying position, the relative movement between the side panel and the central link increases the distance between the second pivot point and the third pivot point, thereby achieving compression of the backrest link assembly.

[0016] According to the utility model, the backrest mounting part is coupled to the seat part assembly through the backrest connecting rod assembly. Through the scissor-type structure of the backrest connecting rod assembly, when the backrest mounting part rotates backward, the backrest connecting rod assembly itself is compressed, and as a whole moves toward the front of the seat unit relative to the ground. Thereby, the gap that may appear between the backrest and the seat part during the posture change of the seat unit is reduced or even eliminated. This not only realizes a true "zero wall" structure and saves installation space, but also reduces or even eliminates the risk of items falling due to the above-mentioned gap, and also avoids pulling out the user's top, achieving a comfortable experience of "zero back rubbing".

[0017] In an alternative embodiment, the leg extension device also includes a second footrest, and in the sitting position, the first footrest and the second footrest are both folded under the seat portion; in the lying position, the backrest is tilted backward, and the highest point of the footstool is higher than the highest point of the backrest, wherein the first footrest and the second footrest both extend forward and upward, and wherein the second footrest is located in front of the first footrest.

[0018] According to a preferred embodiment, the first footrest member and the second footrest member are connected via a footrest extension assembly, and the footrest extension assembly includes a first extension member and a second extension member that are hinged to each other.

[0019] In this embodiment, one end of the first extension member is hinged to the second footrest at the distal end, the other end of the second extension member is hinged to one end of the second extension member, and the other end of the second extension member is hinged to the leg connecting rod connected to the first footrest at the proximal end. By adjusting the hinge position of the first extension member and the second footrest, the front end of the second footrest rises or droops in the lying position, so that the corresponding footrest surface forms an angle with the horizontal plane that is comfortable for the user.

[0020] According to a preferred embodiment, the seat assembly also includes a front swing arm, a rear swing arm, a seat portion linkage and a side panel linkage, wherein the lower ends of the front swing arm and the rear swing arm are respectively pivotally connected to the base assembly, and the upper ends of the front swing arm and the rear swing arm are connected to the side panels via a central linkage, a seat portion linkage and a side panel linkage.

[0021] According to a preferred embodiment, the swinging of the side panels relative to the base assembly causes the backrest assembly and the leg extension device to move relative to the seat assembly, thereby achieving the conversion of the seat unit between the sitting position and the lying position.

[0022] According to a preferred embodiment, in the lying position, the highest point of the first footrest is higher than the highest point of the backrest mounting member, thereby achieving a zero-gravity posture and improving the comfort of the user.

[0023] According to a preferred embodiment, the mechanical extension device further comprises an electric drive device coupled between the base assembly and the side plate.

[0024] In order to solve the above technical problems, the utility model further provides a seat unit, the seat unit comprising the above mechanical extension device and a frame assembly connected to the mechanical extension device, the frame assembly comprising:

[0025] - a seat portion frame, which is fixedly attached to the side panels and is used to support the seat portion of the seat unit;

[0026] - an armrest frame fixedly attached to both sides of the seat frame;

[0027] - A backrest frame which is fixedly attached to the backrest mounting and serves to support the backrest of the seat unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Figure 1 A perspective view showing a mechanical extension device according to one embodiment of the present invention together with a frame assembly in a sitting position;

[0030] Figure 2 A perspective view showing a mechanical extension device according to an embodiment of the present invention, which is in a sitting position;

[0031] Figure 3 Show Figure 2 a side view of the mechanical extension device shown;

[0032] Figure 4 Shown from another direction Figure 2 A partial side view of the mechanical extension device shown;

[0033] Figure 5 A side view of a seating unit according to an embodiment of the present invention is shown in a sitting position;

[0034] FIG6 shows Figure 5 A side view of the seat unit shown in the TV posture position;

[0035] FIG. 7 shows Figure 5 a side view of the seat unit shown in a reclining position;

[0036] Figure 8 A side view of a seating unit according to an embodiment of the present invention is shown in a sitting position;

[0037] FIG. 9 shows Figure 8 a side view of the seating unit shown in the TV posture position; and

[0038] FIG. 10 shows Figure 8 The seat unit is shown in a side view in the lying position. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may include one or more of the features explicitly or implicitly. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here.

[0041] Unless otherwise specified, the “front” or “the front of the seat unit” or “the front of the mechanical extension device” referred to herein refers to the direction toward the leg extension device based on the seat unit; accordingly, the “rear” or “the rear of the seat unit” or “the rear of the mechanical extension device” referred to herein refers to the direction toward the backrest assembly based on the seat unit.

[0042] First, according to Figure 1 A perspective view of a movable seat unit is schematically shown.

[0043] The seat unit includes a mechanical extension device and a frame assembly attached thereto. The frame assembly includes a seat frame 50, an armrest frame 51 fixedly connected to the seat frame 50 on both sides, and a backrest frame 52 movable relative to the seat frame 50. The seat frame 50 is generally constructed as a frame with a rectangular cross section and is used to support the seat frame 50. Figure 5 The seat portion 500 shown in FIG. 7 is preferably elastically constructed, and is particularly preferably constructed as a cushion with good elasticity. The backrest frame 52 can be as Figure 1The backrest frame 52 is configured as two mirror-symmetrical plate-shaped members, but in an embodiment not shown, it can also be configured as a plate-shaped member extending between the two armrest frames 51. The backrest frame 52 is configured to support the armrest frame 52. Figure 5 As for the backrest 520 shown in FIG. 7 , the backrest 520 is preferably designed to be elastic, particularly preferably designed as a cushion with good elasticity.

[0044] like Figure 2 The mechanical extension device shown includes a seat assembly 1, a backrest assembly 2 and a leg extension device 3. The backrest assembly 2 is hinged to the rear of the seat assembly 1, and the leg extension device 3 is hinged to the front of the seat assembly 1. The seat assembly 1 is attached to the seat portion 520 of the seat unit, the backrest assembly 2 is attached to the backrest 520 of the seat unit, and the leg extension device 3 is attached to a footrest (not shown) of the seat unit.

[0045] The seat unit or its mechanical extension device can be changed between a sitting position, a TV position and / or a lying position by the relative movement of the seat component 1, the backrest component 2 and the leg extension device 3. In the sitting position, the backrest 520 is upright and the footrest is folded under the seat portion 500; in the TV position, the backrest 520 does not tilt backward significantly, and the footrest moves upward and forward to the front of the seat portion 500 as the leg extension device 3 is extended; in the lying position, the footrest remains extended to the front of the seat portion 500, while the backrest 520 tilts backward significantly.

[0046] The seat assembly 1 includes a base assembly 11 , a front swing bar 12 , a rear swing bar 13 and a side plate 140 .

[0047] In such Figure 1 In the embodiment shown, the mechanical extension device is used for a floor-standing iron frame seat unit, and the base assembly 11 directly supports the mechanical extension device on the bottom surface, and includes two mirror-symmetrical base longitudinal beams 111 arranged on the left and right sides, and a base front cross beam 112 and a base rear cross beam 113 connecting the two base longitudinal beams 111. However, in an embodiment not shown, the base assembly 11 can also indirectly support the mechanical extension device above the bottom surface, for example, the base assembly 11 is rotatably mounted on a rotating base, or the base assembly 11 is fixedly coupled to the armrest portion of the floor-standing armrest seat unit.

[0048] The front swing arm 112 is hinged at its lower end to the front end of the base longitudinal beam 111 , and the rear swing arm 113 is hinged at its lower end to the rear end of the base longitudinal beam 111 .

[0049] The side plate 140 includes a front support section 140a and a rear support section 140b at its upper portion, which are constructed as sections horizontally bent inward or outward from the side plate 140 and are used to support the auxiliary seat part frame 50a, wherein the seat part frame 50 is fixedly connected to the auxiliary seat part frame 50a.

[0050] The side plate 140 can move relative to the base assembly 11 and also relative to the ground. Figure 3 , Figure 4 As shown, the mechanical extension device also includes a central linkage 15, a seat portion linkage 16 and a side panel linkage 17.

[0051] The central linking member 15 is provided with a plurality of pivot points, and the central linking member 15 is respectively hinged to the backrest assembly 2, the side plate 140, the seat portion linking member 16 and the rear swing rod 13 at these pivot points. One end of the seat portion linking member 16 is hinged to the front swing rod 12 through the side plate linking member 17, and the other end of the seat portion linking member 16 is hinged to the central linking member 15. Thus, the swinging of the front swing rod 12 and the rear swing rod 13 can drive the movement of the side plate 140 relative to the base assembly 11, thereby driving the movement of the backrest assembly 2.

[0052] The backrest assembly 2 includes a backrest mounting member 20 attached to the backrest 520 and a backrest link assembly pivotably connected to the backrest mounting member 20. The backrest mounting member 20 is fixedly connected to the lower section of the backrest frame 52, and the backrest 520 is firmly supported on the backrest frame 52. The backrest link assembly includes a first backrest link 21, a second backrest link 22, and a third backrest link 23. The upper end of the first backrest link 21 is hinged to the front end of the backrest mounting member 20 at the first pivot point P1, the front end of the second backrest link 22 is hinged to the side panel 140 at the second pivot point P2, the rear end of the second backrest link 22 is hinged to the lower end of the third backrest link 23, the middle part of the second backrest link 22 is hinged to the first backrest link 21, the upper end of the third backrest link 23 is hinged to the rear end of the backrest connecting member 20, and the lower end of the first backrest link 21 is hinged to the central link 15 at the third pivot point P3.

[0053] In particular, as shown in Figure 6, the leg extension device 3 is composed of a plurality of links pivotally connected to each other, wherein the rear end of the first leg link 31 is hinged to the side panel 140, the front end of the first leg link 31 is hinged to the rear end of the second leg link 32, the rear end of the third leg link 33 is hinged to the front end of the side panel 140, the front end of the third leg link 33 is hinged to the rear end of the fourth leg link 34, and the front ends of the second leg link 32 and the fourth leg link 34 are respectively hinged to the first footrest 35.

[0054] In addition, the mechanical extension device further includes a first transmission member 18 and a second transmission member 19 which are pivotally connected to each other, one end of the first transmission member 18 is hinged to one end of the second transmission member 19, the other end of the first transmission member 18 is hinged to the side plate 140, and the other end of the second transmission member 19 is hinged to the leg extension device 3, especially to the first leg connecting rod 31. Therefore, when the side plate 140 of the seat assembly 1 moves relative to the base assembly 11, the leg extension device 3 is driven to contract and extend.

[0055] In order to enable the seat unit to be transformed between different positions, an electric drive device 4 is also provided. The side plate 140 includes a motor cross bar 40 fixedly connected to the inner side thereof, and the electric drive device 4 is coupled between the motor cross bar 40 and the base front cross beam 112 of the base assembly 11. The drive device 4 is preferably designed as a linear electric drive, and through the telescopic movement of the linear electric drive, the side plate 140 can be moved relative to the base assembly 11, thereby driving the movement of the backrest assembly 2 and the leg extension device 3, so as to realize the transformation of the seat unit between different positions, such as a sitting position, a TV position and / or a lying position.

[0056] In this embodiment, the electric drive device 4 is designed to enable the mechanical extension device of the seat unit to change between the sitting position, the TV position and the lying position. The electric drive device 4 includes a motor head 41, a motor slide rail 42 fixedly connected to the motor head 41, a motor slider 43 that can slide along the motor slide rail 42 relative to the motor head 41, and a motor connecting rod 44. The motor head 41 is fixedly mounted on the front crossbeam 112 of the base, and one end of the motor connecting rod 44 is hinged to the motor slider 43, and the other end is hinged to the motor crossbar 40.

[0057] The mechanical extension device further includes a first linkage 141, a second linkage 142 and a third linkage 143. The middle portion of the second linkage 142 is rotatably connected to the side plate 140, one end of the second linkage 142 is connected to one end of the first linkage 141, the other end of the first linkage 141 is connected to the front swing bar 12, the other end of the second linkage 142 is connected to one end of the third linkage 143, and the other end of the third linkage 143 is pivotally connected to the first leg link 31 of the leg extension device 3.

[0058] Figure 5 Fig. 7 schematically shows the side view of the seat unit in the sitting position, TV position and lying position. For the sake of clarity, the seat frame and one of the side armrest frames in the frame assembly of the seat unit are omitted.

[0059] Figure 8 to Figure 1 0 also schematically shows a side view of the seat unit in a sitting position, a TV position and a lying position. For the sake of clarity, one side armrest frame and a seat portion and a backrest portion of the frame assembly of the seat unit are omitted.

[0060] When the mechanical extension device is in Figure 5 or Figure 8 In the sitting position shown, the backrest mounting part 20 of the backrest assembly 2 and the backrest 520 are erected upward, and the leg extension device 3 is folded under the seat part 500.

[0061] In the mechanical extension device from Figure 5 or Figure 8 During the process of changing the sitting position shown in FIG. 6 or FIG. 9 to the TV position shown in FIG. 9 , the electric drive device 4 operates, so that the motor slider 43 slides along the motor slide rail 42 toward the motor head 41, so that the distance between the motor head 41 and the motor slider 43 is reduced. In this process, the motor slider 43 moves the side plate 140 forward, that is, toward the direction of the leg stretching device 3, through the motor connecting rod 44, and the front swing rod 12 and the rear swing rod 13 swing forward accordingly. As a result, the first linkage 141 moves forward with the front swing rod 12, and uses the second linkage 142 and the third linkage 143 to push the first leg connecting rod 31; and then the leg stretching device 3 is unfolded. The side plate linkage 17 and the seat portion linkage 16 also move forward with the front swing rod 12, and drive the central linkage 15 to move forward. During this process, the central link 15 moves forward together with the side panel 140, and then uses the first backrest link 21 and the second backrest link 22 to drive the backrest assembly 2 to move forward and downward as a whole, while the backrest mounting member 20 does not tilt significantly, wherein the first pivot point P1 and the second pivot point P2 both move downward and forward.

[0062] During the process of the mechanical stretching device changing from the TV posture position shown in FIG. 6 or FIG. 9 to the lying posture position shown in FIG. 7 or FIG. 10, the electric drive device 4 continues to operate, so that the motor slider 43 slides further toward the motor head 41 along the motor slide rail 42, so that the distance between the motor head 41 and the motor slider 43 is further reduced. In this process, the motor slider 43 moves the side plate 140 further forward, that is, toward the direction of the leg stretching device 3, through the motor connecting rod 44, and the front swing rod 12 and the rear swing rod 13 swing forward with a larger amplitude. When the front swing rod 12 and the rear swing rod 13 swing to the maximum extent, the side plate 140 moves forward significantly relative to the central link 15, so that the distance between the third hinge point P3 between the central link 15 and the first backrest connecting rod 21 and the second hinge point P2 between the side plate 140 and the second backrest connecting rod 22 increases, so that the backrest connecting rod assembly itself is also compressed while moving forward, and the backrest mounting member 20 rotates violently backward around the first pivot point P1. In this process, not only the first pivot point P1 and the second pivot point P2 are moved forward, but also the distance between the first pivot point P1 and the second pivot point P2 is significantly reduced compared to the sitting position and the TV position.

[0063] The backrest frame 52 can have various shapes as required. Figure 8 In the embodiment shown in FIG. 9 , the backrest frame 52 includes a frame lower section 52a and a frame upper section 52b, wherein the lower section 52a is configured to be fixedly connected to the backrest mounting member 20, and the frame upper section 52b transitions with the frame lower section 52a in a stepped section. Figure 8 The side view shown in FIG9 has a lower edge that extends generally in an arc shape. Accordingly, the rear portion of the armrest frame 51 also has an arc-shaped section, thereby forming a gap between the armrest frame 51 and the upper frame section 52b. In the process of changing from the sitting position / TV position to the lying position, the backrest assembly 2 as a whole moves forward together with the side panel 140, and the gap between the armrest frame 51 and the upper frame section 52b remains substantially unchanged during this process, thereby allowing the so-called "T-shaped backrest" to be attached to the backrest frame 52. This design not only improves the user's comfort, but also significantly improves the aesthetic effect of the seat unit.

[0064] The above description has fully disclosed the specific implementation of the utility model. It should be pointed out that any changes made by technicians familiar with the field to the specific implementation of the utility model do not deviate from the scope of the claims of the utility model. Accordingly, the scope of the claims of the utility model is not limited to the above specific implementation.

Claims

1. A mechanical extension device for a movable seat unit, characterized in that The mechanical stretching device comprises: - A base assembly fixedly supported on the ground; - a side panel movably supported above the base assembly for attaching a seat portion of a seating unit; - a backrest assembly pivotally connected to the rear portion of the side panel, comprising a backrest mounting member and a backrest link assembly; and - a central linkage, which is movably connected between the side panels and the backrest assembly; The backrest link assembly includes a first backrest link and a second backrest link, the upper end of the first backrest link is hinged to the front end of the backrest mounting member at a first pivot point, the front end of the second backrest link is hinged to the side plate at a second pivot point, and the middle portion of the second backrest link is hinged to the middle portion of the first backrest link; - a leg extension device pivotally connected to the front of the side panel, comprising a plurality of links pivotally connected to each other, a first footrest for attaching a footstool; The mechanical extension device enables the seat unit to be transformed at least between a sitting position and a lying position, in which the first footrest is folded under the seat part; in the lying position, the backrest is tilted backward and the first footrest is forward and extended compared to the sitting position, and wherein the distance between the first pivot point and the second pivot point is reduced in the lying position compared to the sitting position.

2. The mechanical stretching device according to claim 1, characterized in that: The backrest link assembly is compressed and expanded by the relative movement of the central link and the side plate, thereby realizing the rearward and forward rotation of the backrest mounting member around the first pivot point.

3. The mechanical stretching device according to claim 2, characterized in that: The backrest link assembly also includes a third backrest link, wherein the lower end of the first backrest link is hinged to the central link at a third pivot point, the upper end of the third backrest link is hinged to the rear end of the backrest mounting member, and the lower end of the third backrest link is hinged to the rear end of the second backrest link.

4. The mechanical stretching device according to claim 3, characterized in that: During the transformation of the seat unit from a sitting position to a lying position, the relative movement between the side panels and the central linkage increases the distance between the second pivot point and the third pivot point, thereby achieving compression of the backrest link assembly.

5. The mechanical stretching device according to claim 1, characterized in that: The leg extension device also includes a second footrest, and in the sitting position, the first footrest and the second footrest are both folded under the seat portion; in the lying position, the backrest is tilted backward, and the highest point of the footstool is higher than the highest point of the backrest, wherein the first footrest and the second footrest both extend forward and upward, and wherein the second footrest is located in front of the first footrest.

6. The mechanical stretching device according to claim 5, characterized in that: The first footrest member and the second footrest member are connected via a footrest extension assembly, and the footrest extension assembly includes a first extension member and a second extension member hinged to each other.

7. The mechanical stretching device according to claim 1, characterized in that: The mechanical extension device also includes a front swing arm, a rear swing arm, a seat portion linkage and a side panel linkage, wherein the lower ends of the front swing arm and the rear swing arm are pivotally connected to the base assembly respectively, and the upper ends of the front swing arm and the rear swing arm are connected to the side panels via a central linkage, a seat portion linkage and a side panel linkage.

8. The mechanical stretching device according to claim 7, characterized in that The movement of the side panels relative to the base assembly causes the backrest assembly and the leg extension device to move relative to the side panels, thereby achieving the transformation of the seat unit between the sitting position and the lying position.

9. The mechanical stretching device according to claim 1, characterized in that: In the lying position, the highest point of the first footrest is higher than the highest point of the backrest mounting member.

10. The mechanical stretching device according to claim 1, characterized in that: The mechanical extension device also includes an electric drive device coupled between the base assembly and the side plate.

11. A seating unit according to claim 1, characterized in that: The seat unit comprises: a mechanical extension device according to any one of claims 1 to 10 and a frame assembly connected to the mechanical extension device, the frame assembly comprising: - a seat portion frame, which is fixedly attached to the side panels and is used to support the seat portion of the seat unit; - an armrest frame fixedly attached to both sides of the seat frame; - A backrest frame which is fixedly attached to the backrest mounting and serves to support the backrest of the seat unit.

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