Mechanical extension device for a functional sofa

Abstract

The utility model discloses a kind of mechanical stretching device for functional sofa, belong to functional sofa technical field, including stretching component, support component, drive component, stretching component includes base frame, swing mechanism, seat frame, leg support unit, backrest unit, drive component can drive leg support unit relative to seat frame and unfold forward or fold back, stretching component further includes auxiliary swing bar and tension spring, auxiliary swing bar is hinged to swing mechanism and can reciprocate longitudinally swing relative to swing mechanism, the rear end of tension spring is positioned and set, the front end of tension spring is connected to the swing end of auxiliary swing bar, swing other end of auxiliary swing bar is hinged to seat frame and is connected to leg support unit, tension spring pulls leg support unit forward by auxiliary swing bar to help drive component drive leg support unit and unfold forward.Tension spring can pull leg support unit forward by auxiliary swing bar, uses this traction force to help drive component drive leg support unit and unfold forward, improve the smoothness of stretching component overall movement logic.

Description

Technical Field

[0001] This utility model relates to the field of functional sofa technology, and in particular to a mechanical extension device for functional sofas. Background Technology

[0002] A functional sofa is a sofa with multiple functions. Current functional sofas generally offer three postures: sitting, TV (TV) posture, and reclining posture. Users can adjust the posture according to their needs. The frame of a functional sofa typically includes a leg support assembly, a seat frame assembly, and a backrest assembly. In the sitting posture, the leg support assembly folds into the bottom of the seat frame assembly. In the TV and reclining postures, the leg support assembly extends forward relative to the seat frame assembly. In the reclining posture, the backrest assembly reclines backward relative to the seat frame assembly. When switching from a sitting to a TV posture, the leg support assembly extends forward relative to the seat frame assembly, causing the seat frame assembly and backrest assembly to move forward a small distance. When switching from a TV posture to a reclining posture, the leg support assembly moves the seat frame assembly forward a certain distance, and the seat frame assembly causes the backrest assembly to recline backward.

[0003] The frames of existing functional sofas are generally driven by push rod motors or electric cylinders. Although this driving method can provide a certain range of adjustment, the adjustment process is not smooth enough. In particular, when the leg support assembly unfolds forward from the folded state, dead spots are prone to appear. Higher power driving components are required or users need to manually eliminate dead spots. Utility Model Content

[0004] To address the shortcomings and deficiencies in the existing technology, this utility model provides a mechanical extension device for a functional sofa. The extension component is equipped with a tension spring and an auxiliary swing rod. The tension spring can pull the leg support unit forward through the auxiliary swing rod. This traction force can assist the drive component in driving the leg support unit to extend forward, which helps to improve the smoothness of the overall movement logic of the extension component.

[0005] To achieve the above-mentioned technical objectives, this utility model provides a mechanical extension device for a functional sofa, comprising: The extension assembly has two sets arranged symmetrically on the left and right sides; A support assembly is located between two sets of extension assemblies and is used to connect the two sets of extension assemblies. A drive assembly is located between two sets of extension assemblies and is used to drive the two sets of extension assemblies to move synchronously to switch the posture of the mechanical extension device. The extension assembly includes a base frame, a seat frame, a swing mechanism, a leg support unit, and a backrest unit. The seat frame is movably mounted on the base frame via the swing mechanism. The leg support unit is located at the front end of the seat frame, and the backrest unit is located at the rear end of the seat frame. The drive assembly can drive the leg support unit to extend forward or retract backward relative to the seat frame. The driven leg support unit can drive the backrest unit to move through the seat frame. The extension assembly also includes an auxiliary swing arm and a tension spring. The auxiliary swing arm is hinged to the swing mechanism and can swing back and forth longitudinally relative to the swing mechanism. The rear end of the tension spring is positioned and the front end of the tension spring is connected to one swing end of the auxiliary swing arm. The other swing end of the auxiliary swing arm is hinged to the seat frame and connected to the leg support unit. The tension spring pulls the leg support unit forward through the auxiliary swing arm to assist the drive assembly in driving the leg support unit to extend forward.

[0006] Preferably, an auxiliary connecting rod is provided between the auxiliary swing rod and the leg support unit. The rear end of the auxiliary connecting rod is hinged to the other end of the swing of the auxiliary swing rod, and the front end of the auxiliary connecting rod is connected to the leg support unit. The tension spring applies a forward traction force to the leg support unit through the auxiliary swing rod and the auxiliary connecting rod.

[0007] Preferably, the hinge point between the rear end of the auxiliary link and the auxiliary swing arm is located further away from the hinge point between the auxiliary swing arm and the seat frame than the hinge point between the auxiliary swing arm and the swing mechanism.

[0008] Preferably, the front end of the tension spring is connected to the lower end of the auxiliary swing rod, the rear end of the auxiliary connecting rod is hinged to the upper end of the auxiliary swing rod, and the seat frame is provided with a clearance groove corresponding to the hinge part between the upper end of the auxiliary swing rod and the rear end of the auxiliary connecting rod.

[0009] Preferably, the seat frame has a downwardly extending protrusion corresponding to the auxiliary swing arm, and the auxiliary swing arm is hinged to the protrusion of the seat frame.

[0010] Preferably, the leg support unit includes a front leg support swing arm, a rear leg support swing arm, a front leg support connecting rod, a rear leg support connecting rod, and a main leg support frame plate. The rear ends of the front and rear leg support swing arms are hinged to the front end of the seat frame, staggered from one end to the other. One end of the front leg support connecting rod is hinged to the front end of the front leg support swing arm and the other end is hinged to the main leg support frame plate. The rear leg support connecting rod is hinged to the front leg support connecting rod, with one end hinged to the front end of the rear leg support swing arm and the other end hinged to the main leg support frame plate. The front end of the auxiliary connecting rod is hinged to the front and / or rear leg support swing arms. A tension spring applies a forward traction force to the front and / or rear leg support swing arms of the leg support unit through the auxiliary swing arm and the auxiliary connecting rod.

[0011] Preferably, the drive assembly includes a drive member and a drive rod driven by the drive member. The two ends of the drive rod are respectively fixedly connected to the front swing arm of the leg support unit in the two sets of extension assemblies, and the front end of the auxiliary link is hinged to the rear swing arm of the leg support unit.

[0012] Preferably, the driving component includes a motor part and a telescopic push rod part. The push rod part has a fixed end and a free end. The fixed end of the push rod part is fixedly connected to the motor part, and the free end of the push rod part is hinged to the support assembly. The motor part is rotatably connected to the driving rod.

[0013] Preferably, the leg support unit further includes an unfolding stop pin disposed on the rear connecting rod of the leg support and corresponding to the front swing rod of the leg support. The leg support unit has an unfolded state, and when the leg support unit is switched to the unfolded state, the unfolding stop pin abuts against the front swing rod of the leg support.

[0014] Preferably, the leg support unit further includes a first retractable stop pin disposed on the rear swing arm of the leg support, the leg support unit has a retracted state, and the leg support unit in the retracted state causes the first retractable stop pin to abut against the seat frame; and / or, the leg support unit further includes a second retractable stop pin disposed on the main frame plate of the leg support, the leg support unit has a retracted state, and the leg support unit in the retracted state causes the second retractable stop pin to abut against the rear connecting rod of the leg support.

[0015] Preferably, the swing mechanism includes a follower frame, an intermediate frame, an auxiliary frame, a front holding unit, and a rear holding unit. The follower frame is connected to the support assembly. The auxiliary swing rod is hinged to the front end of the follower frame. The rear end of the follower frame is movably connected to the seat frame via a driven swing rod. The front holding unit includes a first rod and a second rod. The lower end of the first rod is hinged to the base frame, and the upper end is hinged to the front end of the auxiliary frame. The front end of the follower frame, the front end of the intermediate frame, and the upper part of the first rod are hinged to different positions of the second rod. The rear end of the intermediate frame is hinged to the auxiliary frame. The rear holding unit includes a third rod and a fourth rod. The lower end of the third rod is hinged to the base frame. The rear end of the follower frame, the rear end of the auxiliary frame, and the upper end of the third rod are hinged to different positions of the fourth rod.

[0016] Preferably, the base frame is provided with a first swing stop pin for limiting the swing amplitude of the first rod and / or a second swing stop pin for limiting the swing amplitude of the third rod.

[0017] Preferably, the base frame is provided with a first swing stop pin for limiting the swing amplitude of the first rod. The first swing stop pin is provided and located on the rear side of the lower end of the first rod. The mechanical extension device has at least a sitting posture and a lying posture. The swing mechanism has a first holding state corresponding to the sitting posture of the mechanical extension device and a second holding state corresponding to the lying posture of the mechanical extension device. When the swing mechanism is in the first holding state, the first rod abuts against the first swing stop pin. When the swing mechanism switches from the first holding state to the second holding state, the first rod swings forward and separates from the first swing stop pin.

[0018] Preferably, the base frame is provided with a second swing stop pin for limiting the swing amplitude of the third rod. There are two second swing stop pins, which are respectively located on the front and rear sides of the lower end of the third rod. The mechanical extension device has at least a sitting posture and a lying posture. The swing mechanism has a first holding state corresponding to the sitting posture of the mechanical extension device and a second holding state corresponding to the lying posture of the mechanical extension device. When the swing mechanism is in the first holding state, the third rod abuts against the second swing stop pin on the rear side. When the swing mechanism switches from the first holding state to the second holding state, the third rod swings forward until it abuts against the second swing stop pin on the front side.

[0019] Preferably, the follower frame is provided with a third swing stop pin corresponding to the driven swing rod. There are two third swing stop pins, which are respectively located on the front and rear sides of the lower end of the driven swing rod. The seat frame has a rearward state and a forward state corresponding to different postures of the mechanical extension device. When the seat frame is in the rearward state, the driven swing rod abuts against the third swing stop pin on the rear side. When the seat frame switches from the rearward state to the forward state, it drives the driven swing rod to swing forward until it abuts against the third swing stop pin on the front side.

[0020] Preferably, the outer side of the base frame is provided with a number of recesses for avoidance corresponding to each connection position.

[0021] Preferably, the tension spring is located longitudinally between the upper surface of the seat frame and the support assembly.

[0022] Preferably, the rear end of the base frame is provided with an upwardly protruding tongue, and the rear end of the tension spring is hooked to the tongue for positioning; or, the support assembly has a tongue located behind the auxiliary swing arm, and the rear end of the tension spring is hooked to the tongue for positioning; or, the rear end of the tension spring is connected to the rear end of the base frame through a connector; or, the rear end of the tension spring is connected to a position in the support assembly located behind the auxiliary swing arm through a connector.

[0023] By adopting the above technical solution, this utility model has the following advantages: 1. The mechanical extension device for a functional sofa provided by this utility model includes an extension component with a tension spring and an auxiliary swing arm. The auxiliary swing arm is hinged to the swing mechanism and can reciprocate longitudinally relative to the swing mechanism around the hinge point. The rear end of the tension spring is positioned and the front end of the tension spring is connected to one swing end of the auxiliary swing arm. The other swing end of the auxiliary swing arm is hinged to the seat frame and connected to the leg support unit. By utilizing the lever effect of the auxiliary swing arm swinging around the hinge point, the backward pulling force of the tension spring on the auxiliary swing arm is converted into a forward pushing force of the auxiliary swing arm on the leg support unit and the seat frame. This pushing force is used to pull the leg support unit and the seat frame forward, thereby assisting the drive component in driving the leg support unit to extend forward. On the one hand, this improves the smoothness of the overall movement logic of the extension component, allowing the extension component to extend smoothly. On the other hand, it can appropriately reduce the initial driving force of the drive component, avoiding the situation where the drive component is easily damaged due to excessive starting current because the initial driving force required by the leg support unit is large, thus ensuring the performance stability of the drive component. Because the tension spring pulls the leg support unit forward through the lever action of the auxiliary swing rod, the tension spring can be positioned behind the leg support unit, allowing it to be relatively long. This increases the forward pulling force exerted by the tension spring on the leg support unit via the auxiliary swing rod. Since the auxiliary swing rod can reciprocate around the hinge point, its motion stability is ensured, thereby improving the stability of the tension spring's forward pull on the leg support unit, and consequently enhancing the stability of the leg support unit during extension and retraction.

[0024] Therefore, using tension springs and auxiliary swing rods can better eliminate the drive dead points or drive resistance of the drive assembly on the leg support unit in the initial stage of extension, and can also improve the smoothness and stability of the leg support unit's movement in the initial stage of forward extension. After the leg support unit has finished extending, the forward traction force of the tension spring on the leg support unit can keep the leg support unit more stably in the extended posture, thereby improving the stability of the leg support unit's extension. Especially in the event of a drive assembly failure, the forward traction force of the tension spring on the leg support unit can prevent the leg support unit from rapidly retracting backward and falling back, thus preventing the user's legs from suddenly losing support and greatly reducing the speed at which the leg support unit retracts backward when the drive assembly fails, which is beneficial to improving the safety of using the functional sofa. Furthermore, the forward traction force of the tension spring on the leg support unit can dynamically match the user's leg weight, that is, the tension spring can automatically adjust the auxiliary force on the leg support unit according to the user's leg weight, which is beneficial to improving the user's reclining comfort. Each set of extension components is equipped with tension springs, which can improve the synchronization of the movement of the left and right leg support units when the drive assembly is adjusted, thereby improving the overall smoothness of the movement of the extension components.

[0025] 2. An auxiliary connecting rod is installed between the auxiliary swing arm and the leg support unit. The rear end of the auxiliary connecting rod is hinged to the other swing end of the auxiliary swing arm, and the front end of the auxiliary connecting rod is connected to the leg support unit. A tension spring applies a backward pulling force to the swing end of the auxiliary swing arm. Under the leverage of the auxiliary swing arm, the other swing end of the auxiliary swing arm applies a forward pushing force to the leg support unit through the auxiliary connecting rod. Further, the cooperation structure between the tension spring and the leg support unit is rationally designed. By using the auxiliary connecting rod to reasonably reduce the length of the auxiliary swing arm, the tension spring can still smoothly apply a forward traction force to the leg support unit through the auxiliary swing arm and the auxiliary connecting rod, even with a shorter auxiliary swing arm design. This allows the tension spring, auxiliary swing arm, and auxiliary connecting rod to meet the requirements of a compact structural layout, avoiding the situation where a longer auxiliary swing arm would require excessive swing space, resulting in a significant increase in the overall size of the device, thus maintaining a compact overall structure.

[0026] 3. The hinge point between the auxiliary link and the auxiliary swing arm is set further away from the hinge point between the auxiliary swing arm and the seat frame than the hinge point between the auxiliary swing arm and the swing mechanism. This arrangement, which keeps the hinge point between the auxiliary link and the auxiliary swing arm as far away as possible from the swing fulcrum of the auxiliary swing arm, helps to increase the torque applied by the tension spring to the auxiliary link through the auxiliary swing arm, thereby improving the effect of the tension spring in pulling the leg support unit forward.

[0027] 4. The front end of the tension spring is connected to the lower end of the auxiliary swing rod, and the rear end of the auxiliary connecting rod is hinged to the upper end of the auxiliary swing rod. A clearance groove is provided on the seat frame. The hinged part between the upper end of the auxiliary swing rod and the rear end of the auxiliary connecting rod can extend upward from the clearance groove to the seat frame. By utilizing the clearance groove, the movement space of the auxiliary swing rod and the auxiliary connecting rod can be appropriately increased without increasing the outer dimensions of the seat frame. This allows for an appropriate increase in the length of the auxiliary swing rod, enabling the rear end of the auxiliary connecting rod to be positioned further away from the swing fulcrum of the auxiliary swing rod. This helps to further increase the torque applied by the tension spring to the auxiliary connecting rod through the auxiliary swing rod, thereby further improving the effect of the tension spring in pulling the leg support unit forward.

[0028] 5. The seat frame has a downward-extending protrusion corresponding to the auxiliary swing rod. The auxiliary swing rod is hinged to the protrusion of the seat frame. The protrusion allows the auxiliary swing rod to be smoothly hinged to the seat frame without increasing the overall size of the seat frame, and the hinge position between the auxiliary swing rod and the seat frame will not cause motion interference to other components.

[0029] 6. The tension spring can apply a forward traction force to the front and / or rear swing arms of the leg support unit via the auxiliary swing arm and auxiliary connecting rod. Furthermore, the drive rod in the drive assembly, driven by the drive component, is connected to the front swing arm of the leg support unit, and the front end of the auxiliary connecting rod is hinged to the rear swing arm. In other words, the tension spring and drive assembly are connected to different components of the leg support unit. By rationally setting the connection relationships between the drive rod and the tension spring and the leg support unit, the drive rod and tension spring apply forces to different components of the leg support unit. The rigid thrust of the drive rod and the flexible tension of the tension spring act together on the leg support unit, which can better eliminate the start-stop jerking sensation of the leg support unit caused by the drive assembly, thus improving the user experience. In addition, because the tension spring and drive rod apply forces to different components, the tension spring can better absorb the vibration generated by the leg support unit under the drive of the drive rod, making the extension and retraction of the leg support unit smoother. Furthermore, since the front end of the auxiliary link is hinged to the rear swing arm of the leg support, the auxiliary link can avoid the movement path of each component of the leg support unit, thereby avoiding interference with the extension and retraction of the leg support unit and allowing the leg support unit to extend and retract smoothly.

[0030] 7. The drive unit includes a motor part and a telescopic push rod part. The fixed end of the push rod part is fixedly connected to the motor part, and the free end of the push rod part is hinged to the support assembly. The motor part is movably connected to the drive rod. Since the motor part is relatively heavy, connecting the motor part to the drive rod can reduce the shaking generated by the leg support unit when it extends and retracts by utilizing the weight of the motor part, which is beneficial to improving the stability of the leg support unit during movement.

[0031] 8. An unfolding stop pin is installed on the rear connecting rod of the leg support. When the leg support unit is unfolded to the correct position, the unfolding stop pin abuts against the front swing rod of the leg support, preventing the leg support unit from continuing to move and keeping it in the unfolded state. The unfolding stop pin limits the range of motion of the leg support unit during unfolding, preventing excessive movement of the leg support unit. When the leg support unit is in the unfolded state, the abutment between the unfolding stop pin and the front swing rod of the leg support can also be used to keep the leg support unit stably in the unfolded state, which helps to improve the structural stability of the leg support unit in the unfolded state.

[0032] 9. A first retraction stop pin is provided on the rear swing arm of the leg support, and a second retraction stop pin is provided on the main frame plate of the leg support. When the leg support unit is switched to the retracted state, the first retraction stop pin abuts against the seat frame, and the second retraction stop pin abuts against the rear connecting rod of the leg support. The movement range of the relevant components of the leg support unit during the retraction stroke is limited by the two retraction stop pins to avoid the leg support unit moving excessively when retracting.

[0033] 10. The auxiliary swing arm is hinged to the front end of the follower frame. A reasonable hinge relationship between the auxiliary swing arm and the swing mechanism is designed so that the auxiliary swing arm can be positioned as far forward as possible to cooperate with the leg support unit, while also ensuring that the auxiliary swing arm does not interfere with the movement of the swing mechanism itself. Furthermore, since the auxiliary swing arm is hinged to the follower frame, the tension spring applies backward resistance to the swing mechanism through the auxiliary swing arm during the device's unfolding process. The leg support unit, pulled forward by the tension spring, unfolds forward first, followed by the swing mechanism, which is subjected to backward resistance by the tension spring. During the device's retraction process, the tension spring applying backward resistance to the swing mechanism helps the swing mechanism drive the seat frame to move backward and return to its original position. A reasonable orientation of the force applied by the tension spring to the swing mechanism through the auxiliary swing arm helps improve the smoothness of the overall unfolding and retraction of the device.

[0034] 11. The first swing stop pin on the base frame is used to limit the swing amplitude of the first rod, and the second swing stop pin is used to limit the swing amplitude of the second rod. Further, when the entire device is in a seated posture, the swing mechanism is in a first holding state. At this time, the first rod is held stable by contact with the first swing stop pin, and the third rod is held stable by contact with the rear second swing stop pin. The contact between the first rod and the first swing stop pin, and the contact between the third rod and the second swing stop pin, stabilizes the swing mechanism, thus maintaining the overall posture of the device. When the entire device is in a reclining posture, the swing mechanism switches from the first holding state to the second holding state. At this time, the first rod swings forward to disengage from the first swing stop pin, and the third rod swings forward to contact the front second swing stop pin. The contact between the third rod and the second swing stop pin stabilizes the swing structure, thus maintaining the overall posture of the device.

[0035] 12. A third swing stop pin corresponding to the driven swing arm is provided on the follower frame. Furthermore, there are two third swing stop pins, located on the front and rear sides of the lower end of the driven swing arm, respectively. When the mechanical extension device is in a certain posture, causing the seat frame to be in a rearward position, the driven swing arm abuts against the rear third swing stop pin, keeping the driven swing arm in a stable position, thus allowing the seat frame to be stably held in the rearward position. When the mechanical extension device switches to another posture, the seat frame switches from a rearward to a forward position. The moving seat frame drives the driven swing arm to swing forward until it abuts against the front third swing stop pin. The driven swing arm abuts against the front third swing stop pin, keeping its position stable, thus allowing the seat frame to be stably held in the forward position.

[0036] 13. Several clearance grooves are provided on the outer side of the base frame corresponding to each connection position. The clearance grooves are used to ensure that the connectors connecting the relevant components to the base frame do not protrude from the outer surface of the base frame, thus avoiding the connectors on the base frame from being hit by other objects, ensuring the structural strength of the relevant components connected to the base frame, and thus ensuring the overall structural stability of the device.

[0037] 14. The tension spring is located longitudinally between the upper surface of the seat frame and the support assembly. A reasonable longitudinal placement of the tension spring relative to the overall structure allows for a reasonable longitudinal placement of the auxiliary swing arm and auxiliary connecting rod. This ensures that the tension spring, auxiliary swing arm, and auxiliary connecting rod do not significantly affect the original structural layout of the device, contributing to a compact overall structure. If the tension spring is higher than the upper surface of the seat frame, other components or objects in the sofa may easily get stuck, preventing the tension spring from smoothly pulling the leg support unit forward via the auxiliary swing arm and auxiliary connecting rod. If the tension spring is lower than the support assembly, the auxiliary swing arm or auxiliary connecting rod will also be lower than the support assembly, potentially causing movement interference and hindering the smooth extension and retraction of the leg support unit. Attached Figure Description

[0038] Figure 1 This is a structural diagram of the mechanical extension device in the TV posture in Embodiment 1; Figure 2 This is a partial structural diagram of the unilateral extension component of the mechanical extension device in Embodiment 1 when it is in the TV posture; Figure 3 This is a structural diagram of the mechanical extension device in the seated position in Embodiment 1; Figure 4 This is a structural diagram of the mechanical extension device in the first embodiment when it is in a lying position; Figure 5 This is a structural diagram of the leg support unit, tension spring, auxiliary swing arm, and auxiliary connecting rod in Embodiment 1 when the leg support unit is deployed; Figure 6This is a structural diagram of the leg support unit, tension spring, auxiliary swing rod, and auxiliary connecting rod in Embodiment 1 when the leg support unit is retracted; Figure 7 This is a structural diagram of the swing mechanism in Embodiment 1; Figure 8 This is a structural diagram of the swing mechanism in Embodiment 1 from another angle; Figure 9 This is a structural diagram of the base frame, the first rod, and the third rod in Example 1; Figure 10 This is a structural diagram of the backrest unit in Embodiment 1 when the mechanical extension device is in the TV posture; Figure 11 This is a structural diagram of the backrest unit in Embodiment 1 when the mechanical extension device is in a lying position; Figure 12 This is a structural diagram of the front connecting rod of the backrest in Embodiment 1; Figure 13 This is a comparison diagram of the mechanical extension device in Example 1 under three postures; Figure 14 This is a perspective view of a single-sided structure of the fuselage extension device in Embodiment 1 when it is in a seated posture. Figure 15 This is a perspective view of a single-sided structure of the fuselage extension device in Embodiment 1 when it is in the TV posture. Figure 16 This is a perspective view of the single-sided structure of the fuselage extension device in Embodiment 1 when it is in a lying position.

[0039] In the diagram, 10 - mechanical extension device. 100-Extension assembly, 110-Base frame, 111-Linger plate, 112-Sinkhole, 122-Protrusion, 123-Allowing groove, 120-Seat frame, 121-Extension plate, 130-Leg support unit, 131-Leg support front swing arm, 132-Leg support rear swing arm, 133-Leg support front link, 134-Leg support rear link, 135-Leg support main frame plate, 1351-Main support plate, 136-Leg support auxiliary support rod, 1361-Auxiliary support plate, 137-Leg support auxiliary link, 1381-First retraction stop pin, 1382-Second retraction stop pin, 1383-Expansion stop pin, 140-Backrest unit, 141-Backrest frame plate, 142-Follower link, 143-Follower swing arm, 144-Backrest front link, 1441-Corner At the corner, 145-backrest connecting rod, 146-intermediate connecting rod, 1481-first limit stop pin, 1482-second limit stop pin, 1483-third limit stop pin, 151-tension spring, 152-auxiliary swing rod, 1521-lug, 153-auxiliary connecting rod, 160-swing mechanism, 161-follower frame, 1611-front protrusion, 1612-rear protrusion, 162-intermediate frame, 163-auxiliary frame, 164-front holding unit, 1641-first rod, 1642-second rod, 165-rear holding unit, 1651-third rod, 1652-fourth rod, 166-driven swing rod, 1671-first swing stop pin, 1672-second swing stop pin, 1673-third swing stop pin 200 - Support assembly, 210 - First support rod, 220 - Second support rod, 230 - Third support rod. 300-Drive assembly, 310-Driver component, 311-Motor part, 312-Push rod part, 312a-Fixed end, 312b-Free end, 320-Drive rod, 330-Transmission connecting rod. 20 - Relying on a backpack. Detailed Implementation

[0040] This utility model provides a mechanical extension device for a functional sofa, comprising: The extension assembly has two sets arranged symmetrically on the left and right sides; A support assembly is located between two sets of extension assemblies and is used to connect the two sets of extension assemblies. A drive assembly is located between two sets of extension assemblies and is used to drive the two sets of extension assemblies to move synchronously to switch the posture of the mechanical extension device. The extension assembly includes a base frame, a seat frame, a swing mechanism, a leg support unit, and a backrest unit. The seat frame is movably mounted on the base frame via the swing mechanism. The leg support unit is located at the front end of the seat frame, and the backrest unit is located at the rear end of the seat frame. The drive assembly can drive the leg support unit to extend forward or retract backward relative to the seat frame. The driven leg support unit can drive the backrest unit to move through the seat frame. The extension assembly also includes an auxiliary swing arm and a tension spring. The auxiliary swing arm is hinged to the swing mechanism and can swing longitudinally back and forth relative to the swing mechanism. The rear end of the tension spring is positioned and the front end of the tension spring is connected to one swing end of the auxiliary swing arm. The other swing end of the auxiliary swing arm is hinged to the seat frame and connected to the leg support unit. The tension spring pulls the leg support unit forward through the auxiliary swing arm to assist the drive assembly in driving the leg support unit to extend forward.

[0041] The lever action of the auxiliary swing arm, which can oscillate around the hinge point, converts the backward tension of the tension spring on the auxiliary swing arm into a forward thrust of the auxiliary swing arm on the leg support unit and seat frame. This thrust pulls the leg support unit and seat frame forward, thus assisting the drive assembly in driving the leg support unit forward. This improves the smoothness of the overall motion logic of the extension assembly, allowing it to extend smoothly. Furthermore, it appropriately reduces the initial driving force of the drive assembly, preventing damage due to excessive starting current caused by a large initial driving force required by the leg support unit, ensuring the performance stability of the drive assembly. Since the tension spring pulls the leg support unit forward through the lever action of the auxiliary swing arm, the spring can be positioned behind the leg support unit, allowing for a longer spring. This increases the forward pulling force exerted by the spring on the leg support unit through the auxiliary swing arm. The reciprocating swing arm around the hinge point ensures the stability of its movement, thereby improving the stability of the spring pulling the leg support unit forward through the auxiliary swing arm, and further enhancing the stability of the leg support unit during extension and retraction.

[0042] Therefore, using tension springs and auxiliary swing rods can better eliminate the drive dead points or drive resistance of the drive assembly on the leg support unit in the initial stage of extension, and can also improve the smoothness and stability of the leg support unit's movement in the initial stage of forward extension. After the leg support unit has finished extending, the forward traction force of the tension spring on the leg support unit can keep the leg support unit more stably in the extended posture, thereby improving the stability of the leg support unit's extension. Especially in the event of a drive assembly failure, the forward traction force of the tension spring on the leg support unit can prevent the leg support unit from rapidly retracting backward and falling back, thus preventing the user's legs from suddenly losing support and greatly reducing the speed at which the leg support unit retracts backward when the drive assembly fails, which is beneficial to improving the safety of using the functional sofa. Furthermore, the forward traction force of the tension spring on the leg support unit can dynamically match the user's leg weight, that is, the tension spring can automatically adjust the auxiliary force on the leg support unit according to the user's leg weight, which is beneficial to improving the user's reclining comfort. Each set of extension components is equipped with tension springs, which can improve the synchronization of the movement of the left and right leg support units when the drive assembly is adjusted, thereby improving the overall smoothness of the movement of the extension components.

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the terms "upper," "lower," "left," "right," "longitudinal," "lateral," "inner," "outer," "vertical," "horizontal," "top," and "bottom," etc., which indicate orientation or positional relationship, are based solely on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device / component referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0044] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined. Example

[0046] Combination Figures 1 to 16 This utility model provides a mechanical extension device 10 for a functional sofa, comprising an extension component 100, a support component 200, and a drive component 300. Two sets of extension components 100 are symmetrically arranged on the left and right sides. The support component 200 is located between the two sets of extension components 100 and connects them. The drive component 300 is located between the two sets of extension components 100 and drives them to move synchronously to switch the posture of the mechanical extension device 10. The extension component 100 includes a base frame 110, a seat frame 120, a swing mechanism 160, a leg support unit 130, and a backrest unit 140. The base frame 110 can be fixedly installed. The seat frame 120 is movably mounted on the base frame 110 via the swing mechanism 160. The leg support unit 130 is located at the front end of the seat frame 120, and the backrest unit 140 is located at the rear end of the seat frame 120. The drive assembly 300 can drive the leg support unit 130 to extend forward or retract backward relative to the seat frame 120, and the driven leg support unit 130 can drive the backrest unit 140 to move through the seat frame 120.

[0047] Combination Figure 1 , Figure 5 , Figure 6 The leg support unit 130 includes a front leg support swing arm 131, a rear leg support swing arm 132, a front leg support connecting rod 133, a rear leg support connecting rod 134, and a leg support main frame plate 135. The rear end of the front leg support swing arm 131 is hinged to the front end of the seat frame 120, the front end of the front leg support swing arm 131 is hinged to the rear end of the front leg support connecting rod 133, and the front end of the front leg support connecting rod 133 is hinged to the leg support main frame plate 135. The rear end of the rear leg support swing arm 132 is hinged to the front end of the seat frame 120 and is positioned rearward relative to the rear end of the front leg support swing arm 131, the front end of the rear leg support swing arm 132 is hinged to the rear end of the rear leg support connecting rod 134, and the front end of the rear leg support connecting rod 134 is hinged to the leg support main frame plate 135 and is positioned rearward relative to the front end of the front leg support connecting rod 133. The rear connecting rod 134 of the leg support intersects with the front swing rod 131 of the leg support, and the intersection of the two is hinged together.

[0048] In addition, in this embodiment, the leg support unit 130 also includes a leg support auxiliary support rod 136 and a leg support auxiliary connecting rod 137. The rear end of the leg support auxiliary support rod 136 is hinged to the front end of the leg support front connecting rod 133. The rear end of the leg support auxiliary connecting rod 137 is hinged to the leg support main frame plate 135. The front end of the leg support auxiliary connecting rod 137 is hinged to the approximate middle part of the leg support auxiliary support rod 136. The hinge point between the leg support auxiliary support rod 136 and the leg support front connecting rod 133 is positioned forward relative to the hinge point between the leg support main frame plate 135 and the leg support front connecting rod 133. The hinge point between the leg support auxiliary connecting rod 137 and the leg support main frame plate 135 is positioned upward relative to the hinge point between the leg support front connecting rod 133 and the leg support main frame plate 135.

[0049] In this embodiment, the leg support unit 130 is connected to a leg rest component. The leg rest component has components such as a base plate, filling material, and outer fabric. The filling material of the leg rest component can be a single material or a mixture of materials such as down, sponge, wool, and cotton. The outer fabric of the leg rest component can be made of materials such as cotton cloth, linen, genuine leather, and artificial leather. No specific limitations are made here regarding the filling material and outer fabric of the leg rest component. The leg rest component can adopt a segmented structure. For example, the leg rest component has two parts distributed front and back. In order to support the two leg rest components, the main frame plate 135 of the leg support has a main support plate 1351 extending towards the center of the device, and the secondary support rod 136 of the leg support has a secondary support plate 1361 extending towards the center of the device. The base plate of the rear leg rest component is fixedly connected to the main support plate 1351 of the left and right leg support units 130, and the base plate of the front leg rest component is fixedly connected to the secondary support plate 1361 of the left and right leg support units 130. The forward-moving leg support unit 130 causes the leg rest to move upward and unfold, providing support for the user's legs. The backward-moving leg support unit 130 causes the leg rest to move downward and fold to the front and bottom of the seat frame 120, preventing it from interfering with the user's normal sitting posture. In this specific embodiment, the main support plate 1351 and the main leg support frame 135 can be integrally formed or separately formed and then fixed together; the secondary support plate 1361 and the secondary leg support rod 136 can be integrally formed or separately formed and then fixed together.

[0050] In other embodiments of this invention, the leg support auxiliary rod 136, the leg support auxiliary connecting rod 137, and the auxiliary support plate 1361 can be omitted. In this case, only the main support plate 1351 is used to support a single leg support piece.

[0051] Furthermore, an unfolding stop pin 1383 is provided on the rear connecting rod 134 of the leg support. Combined with... Figure 1 The leg support unit 130 has an extended state. When the leg support unit 130 is in the extended state, the front swing arm 131 of the leg support abuts against the top side of the extension stop pin 1383. The extension stop pin 1383 provides limiting support to the front swing arm 131, thereby keeping the front swing arm 131 in a stable position, and thus keeping the leg support unit 130 as a whole in a stable state. The extension stop pin 1383 limits the range of motion of the leg support unit 130 when it is extended, preventing the leg support unit 130 from being over-extended and unable to retract to its original position.

[0052] Furthermore, a first retractable stop pin 1381 is provided on the rear swing arm 132 of the leg support, and a second retractable stop pin 1382 is provided on the main frame plate 135 of the leg support. Combined with... Figure 3The leg support unit 130 has a retracted state. When the leg support unit 130 is in the retracted state, the first retracting stop pin 1381 abuts against the bottom side of the seat frame 120, and the second retracting stop pin 1382 abuts against the front side of the leg support rear connecting rod 134. The first retracting stop pin 1381 limits the swing amplitude of the leg support rear swing rod 132 when it moves backward to retract, and the second retracting stop pin 1382 limits the swing amplitude of the leg support main frame plate 135 when it moves backward to retract. The first retracting stop pin 1381 and the second retracting stop pin 1382 limit the travel of each component of the leg support unit 130 when it moves backward to retract, so as to avoid excessive travel of the components of the leg support unit 130 and thus ensure that the leg support unit 130 can be retracted and extended smoothly. In other embodiments of this invention, the leg support unit 130 may only have a first retractable stop pin 1381 on the rear swing arm 132 of the leg support, and the movement range of the leg support unit 130 when switching from the extended state to the retracted state is limited only by the contact between the first retractable stop pin 1381 and the seat frame 120; or, the leg support unit 130 may only have a second retractable stop pin 1382 on the main frame plate 135 of the leg support, and the movement range of the leg support unit 130 when switching from the extended state to the retracted state is limited only by the contact between the second retractable stop pin 1382 and the rear connecting rod 134 of the leg support.

[0053] Combination Figure 7 , Figure 8In this embodiment, the seat frame 120 is movably mounted on the base frame 110 via a swing mechanism 160. Specifically, the swing mechanism 160 is located substantially outside the seat frame 120 and includes a follower frame 161, an intermediate frame 162, an auxiliary frame 163, a front holding unit 164, and a rear holding unit 165. The follower frame 161 is connected to the support assembly 200, and the rear end of the follower frame 161 is movably connected to the seat frame 120 via a driven swing rod 166. The front holding unit 164 includes a first rod 1641 and a second rod 1642. The lower end of the first rod 1641 is hinged to the base frame 110, the upper end of the first rod 1641 is hinged to the front end of the auxiliary frame 163, the upper end of the second rod 1642 is hinged to the upper part of the first rod 1641, the lower end of the first rod 1641 is hinged to the front end of the follower frame 161, the front end of the intermediate frame 162 is hinged to the middle part of the second rod 1642, and the rear end of the intermediate frame 162 is approximately hinged to the middle part of the auxiliary frame 163. The front end of the follower frame 161, the front end of the intermediate frame 162, and the upper end of the first rod 1641 are hinged to different positions of the second rod 1642. The rear retaining unit 165 includes a third rod 1651 and a fourth rod 1652. The lower end of the third rod 1651 is hinged to the base frame 110, the upper end of the third rod 1651 is hinged to the upper end of the fourth rod 1652, the lower end of the fourth rod 1652 is hinged to the rear end of the follower frame 161, the rear end of the auxiliary frame 163 is hinged to the middle part of the fourth rod 1652, and the rear end of the follower frame 161, the rear end of the auxiliary frame 163, and the upper end of the third rod 1651 are hinged to different positions of the fourth rod 1652. Furthermore, the swing mechanism 160 is located inside the base frame 110. Simultaneously, the follower frame 161, intermediate frame 162, and auxiliary frame 163 of the swing mechanism 160 are distributed sequentially from near to far relative to the seat frame 120. The follower frame 161 is located outside the seat frame 120 and close to it; the auxiliary frame 163 is located outside the seat frame 120 and away from it; and the intermediate frame 162 is located between the follower frame 161 and the auxiliary frame 163. The front holding unit 164 is located in the left-right direction between the front end of the auxiliary frame 163 and the front part of the base frame 110, and the rear holding unit 165 is located in the left-right direction between the rear end of the auxiliary frame 163 and the rear part of the base frame 110. The first rod 1641 and the second rod 1642 of the front holding unit 164 can form a "V" shaped holding structure with different specific shapes when the device is in different postures. Similarly, the third rod 1651 and the fourth rod 1652 of the rear holding unit 165 can also form a "V" shaped holding structure with different specific shapes when the device is in different postures. By combining the front and rear holding units with the base frame 110, two stable triangular support structures are formed, so that the swing mechanism 160 can maintain structural stability when the device is in a certain posture. This also allows components such as the seat frame 120 to maintain a stable state when the device is in a certain posture, avoiding the situation where the swing mechanism 160 moves under the action of load force, causing the device to lose its posture stability.

[0054] Combination Figure 1 In this embodiment, the support assembly 200 includes a first support rod 210, a second support rod 220, and a third support rod 230 distributed from front to back. The front and rear ends of the bottom side of the follower frame 161 are respectively provided with a front protrusion 1611 and a rear protrusion 1612 extending toward the center of the device. The left and right ends of the first support rod 210 are fixedly connected to the front protrusions 1611 of the left and right follower frames 161, respectively. The left and right ends of the second support rod 220 are fixedly connected to the rear protrusions 1612 of the left and right follower frames 161, respectively. The left and right ends of the third support rod 230 are fixedly connected to the rear ends of the left and right base frames 110, respectively. In this specific embodiment, the front protrusion 1611 and the follower frame 161 can be integrally formed or separately formed and then fixed together; the rear protrusion 1612 and the follower frame 161 can be integrally formed or separately formed and then fixed together; of course, the front protrusion 1611 can also be integrally formed with the first support rod 210, and the rear protrusion 1612 can also be integrally formed with the second support rod 220. Furthermore, the cross-sectional shape of the first support rod 210, the second support rod 220, and the third support rod 230 along the direction perpendicular to their length can be set to a reasonable shape such as a hollow rectangle or a hollow circle; no specific limitation is placed on the cross-sectional shape of each support rod. Moreover, each support rod can be a straight rod, or a reasonable shape such as an S-shaped rod or an arc-shaped rod; no specific limitation is placed on the shape of each support rod in the length direction. It is understood that the specific structure of the support component 200 is not limited to the foregoing description and the accompanying drawings. Other existing structural methods can also be used to connect the left and right sets of extension components 100 and enable the two sets of extension components 100 to move synchronously.

[0055] Combination Figure 1In this embodiment, the drive assembly 300 includes a drive member 310 and a drive rod 320 driven by the drive member 310. The left and right ends of the drive rod 320 are respectively fixedly connected to the rear of the front swing rod 131 of the leg support unit 130 on the left and right sides via transmission connecting rods 330. Further, the drive member 310 can be a push rod motor. In this case, the drive member 310 includes a motor part 311 and a telescopic push rod part 312. The motor part 311 can be movably connected to the drive rod 320 via a connecting plate. One end of the connecting plate is fixedly connected to the drive rod 320, and the motor part 311 is hinged to the other end of the connecting plate. This allows the motor part 311 to maintain a transmission connection with the drive rod 320 while also allowing the motor part 311 to be rotatably set relative to the drive rod 320, avoiding interference between the motor part 311 and the drive rod 320 that would prevent the push rod motor from smoothly driving the drive rod 320. The push rod portion 312 has a fixed end 312a and a free end 312b. The fixed end 312a of the push rod portion 312 is fixedly connected to the motor portion 311, and the free end 312b of the push rod portion 312 is hinged to the third support rod 230 of the support assembly 200. The drive rod 320 is longitudinally higher than the first support rod 210 and the second support rod 220, so that the push rod portion 312 is always higher than the first support rod 210 and the second support rod 220, avoiding collision between the push rod portion 312 and the first support rod 210 or the second support rod 220. Since the motor portion 311 is relatively heavy, its front-mounted connection to the drive rod 320 facilitates the use of the weight of the motor portion 311 to reduce the vibration generated by the leg support unit 130 during extension and retraction, which helps to improve the stability of the leg support unit 130 during movement. When the drive member 310 extends the push rod portion 312, it drives the drive rod 320 to move obliquely upward and forward, thereby causing the leg support unit 130 to unfold forward. When the drive member 310 shortens the push rod portion 312, it drives the drive rod 320 to move obliquely downward and backward, thereby causing the leg support unit 130 to retract backward. In an alternative embodiment, the motor portion 311 of the drive member 310 can also be movably hinged to the third support rod 230, in which case the free end of the push rod portion 312 is hinged to the drive rod 320. In other embodiments of this embodiment, the drive member 310 can also be replaced by a telescopic component such as an electric cylinder, and the drive member 310 of the drive assembly 300 is not specifically limited here.

[0056] Combination Figure 2 , Figure 5In this embodiment, the extension assembly 100 further includes a tension spring 151 and an auxiliary swing rod 152. The auxiliary swing rod 152 is hinged to the swing mechanism 160 and can swing longitudinally back and forth relative to the swing mechanism 160. The rear end of the tension spring 151 is positioned and the front end of the tension spring 151 is connected to one swing end of the auxiliary swing rod 152. The other swing end of the auxiliary swing rod 152 is hinged to the seat frame 120 and connected to the leg support unit 130. The tension spring 151 pulls the leg support unit 130 forward through the auxiliary swing rod 152 to assist the drive assembly 300 in driving the leg support unit 130 to extend forward. When the drive assembly 300 drives the leg support unit 130 to extend forward, the tension spring 151, through the auxiliary swing rod 152, exerts a forward traction force on the leg support unit 130 in the initial stage of drive, which can help the leg support unit 130 extend forward, thus enabling the leg support unit 130 to extend smoothly. The tension spring 151 and the auxiliary swing rod 152 can better eliminate the drive dead point or drive resistance of the drive assembly 300 on the leg support unit 130 in the initial stage of extension, and can also improve the smoothness and stability of the movement of the leg support unit 130 in the initial stage of forward extension. Furthermore, after the leg support unit 130 has extended, the forward traction force of the tension spring 151 on the leg support unit 130 can help maintain the leg support unit 130 more stably in its extended posture, thereby improving the stability of the leg support unit 130's extension. Especially in the event of a malfunction in the drive assembly 300, the forward traction force of the tension spring 151 on the leg support unit 130 can prevent the leg support unit 130 from rapidly retracting backward and causing a fall, thus preventing the user's legs from suddenly losing support and greatly reducing the speed at which the leg support unit 130 retracts backward when the drive assembly 300 malfunctions, which is beneficial to improving the safety of using the functional sofa. Moreover, the forward traction force of the tension spring 151 on the leg support unit 130 can dynamically match the user's leg weight, that is, the tension spring 151 can automatically adjust the auxiliary force on the leg support unit 130 according to the user's leg weight, which is beneficial to improving the user's reclining comfort. Each extension component 100 is equipped with a tension spring 151, which can improve the motion synchronization of the left and right leg support units 130 when the drive component 300 is driven and adjusted, thereby improving the overall smoothness of the movement of the extension component 100.

[0057] Furthermore, in this embodiment, an auxiliary connecting rod 153 is also provided between the auxiliary swing rod 152 and the leg support unit 130. The rear end of the auxiliary connecting rod 153 is hinged to the other swing end of the auxiliary swing rod 152, and the front end of the auxiliary connecting rod 153 is connected to the leg support unit 130. The tension spring 151 applies a forward traction force to the leg support unit 130 through the auxiliary swing rod 152 and the auxiliary connecting rod 153. Figure 5The auxiliary swing arm 152 is hinged to the swing mechanism 160 at approximately the middle. The front end of the tension spring 151 is connected to the lower end of the auxiliary swing arm 152. The rear end of the auxiliary connecting rod 153 is hinged to the upper end of the auxiliary swing arm 152. The front end of the auxiliary connecting rod 153 is hinged to the rear end of the leg support rear swing arm 132. The tension spring 151 applies a backward pulling force F1 to the lower end of the auxiliary swing arm 152. Under the lever action of the auxiliary swing arm 152, the upper end of the auxiliary swing arm 152 applies a forward pushing force F2 to the auxiliary connecting rod 153. The auxiliary connecting rod 153 transmits the pushing force F2 to the leg support rear swing arm 132. This pushing force F2 constitutes a forward traction force on the leg support unit 130. That is, the tension spring 151 causes the leg support unit 130 to be subjected to a forward traction force through the auxiliary swing arm 152 and the auxiliary connecting rod 153, thereby achieving the purpose of the tension spring 151 pulling the leg support unit 130 forward. The thrust F2 at the upper end of the auxiliary swing rod 152 is transmitted to the leg support unit 130 through the auxiliary connecting rod 153. By using the auxiliary connecting rod 153 to reasonably reduce the length of the auxiliary swing rod 152, the tension spring 151 can still smoothly apply forward traction to the rear swing rod 132 of the leg support through the auxiliary swing rod 152 and the auxiliary connecting rod 153, even with the small size design of the auxiliary swing rod 152. This allows the tension spring 151 and the auxiliary swing rod 152 to meet the requirements of a compact layout, avoiding the situation where the length of the auxiliary swing rod 152 is too large, resulting in an excessive swing space and a significant increase in the overall size of the device, thus keeping the overall structure of the device compact.

[0058] In this embodiment, since the end of the drive rod 320 is fixedly connected to the front swing arm 131 of the leg support and the front end of the auxiliary connecting rod 153 is hinged to the rear swing arm 132 of the leg support, the specific connecting components of the drive rod 320 and the auxiliary connecting rod 153 to the leg support unit 130 are reasonably set. This allows the drive rod 320 and the tension spring 151 to apply forces to different components of the leg support unit 130. The rigid thrust of the drive rod 320 and the flexible tension of the tension spring 151 act together on the leg support unit 130, which can better eliminate the start-stop jerking sensation of the drive assembly 300 on the leg support unit 130, thus improving the user experience. In addition, since the tension spring 151 and the drive rod 320 apply forces to different components, the tension spring 151 can better absorb the vibration generated by the leg support unit 130 under the drive of the drive rod 320, making the extension and retraction of the leg support unit 130 more stable. Furthermore, since the front end of the auxiliary link 153 is hinged to the rear swing arm 132 of the leg support, the auxiliary link 153 can avoid the movement path of each component of the leg support unit 130, thereby avoiding the situation where the auxiliary link 153 causes movement interference to the extension and retraction of the leg support unit 130, so that the leg support unit 130 can extend and retract smoothly. In an alternative embodiment, provided that the auxiliary link 153 does not interfere with the movement of the leg support unit 130, the front end of the auxiliary link 153 can also be hinged to the front swing arm 131 of the leg support, and the tension spring 151 applies a forward traction force to the front swing arm 131 of the leg support unit 130 through the auxiliary swing arm 152 and the auxiliary link 153; or, provided that the auxiliary link 153 does not interfere with the movement of the leg support unit 130, the front end of the auxiliary link 153 can also be hinged to both the front swing arm 131 and the rear swing arm 132 of the leg support, and the tension spring 151 applies a forward traction force to both the front swing arm 131 and the rear swing arm 132 of the leg support unit 130 through the auxiliary swing arm 152 and the auxiliary link 153. In an alternative embodiment, provided that the drive assembly 300 can smoothly drive the leg support unit 130, the left and right ends of the drive rod 320 can also be fixedly connected to the rear of the rear swing arm 132 of the leg support.

[0059] In this embodiment, the auxiliary swing rod 152 is specifically hinged to the front end of the follower frame 161 in the swing mechanism 160. The auxiliary swing rod 152 can swing back and forth longitudinally with the hinge point between itself and the follower frame 161 as the swing fulcrum. Furthermore, the auxiliary swing rod 152 is located inside the follower frame 161 to avoid interference between the auxiliary swing rod 152 and other components of the swing mechanism 160.

[0060] In a preferred embodiment, the seat frame 120 is provided with a downwardly extending protrusion 122 corresponding to the auxiliary swing rod 152. The upper part of the auxiliary swing rod 152 is hinged to the protrusion 122 of the seat frame 120. The protrusion 122 allows the auxiliary swing rod 152 to be smoothly hinged to the seat frame 120 without increasing the overall size of the seat frame 120, and the hinge position between the auxiliary swing rod 152 and the seat frame 120 will not cause motion interference to other components.

[0061] Since the rear end of the auxiliary link 153 is hinged to the upper end of the auxiliary swing rod 152, the hinge point between the auxiliary link 153 and the auxiliary swing rod 152 is located further away from the hinge point between the auxiliary swing rod 152 and the seat frame 120 than the hinge point between the auxiliary swing rod 152 and the follower frame 161. In other words, the hinge point between the auxiliary link 153 and the auxiliary swing rod 152 is located as far away as possible from the swing fulcrum of the auxiliary swing rod 152. This increases the torque applied by the tension spring 151 to the auxiliary link 153 through the auxiliary swing rod 152, which helps to increase the forward traction force applied by the tension spring 151 to the leg support unit 130 through the auxiliary swing rod 152 and the auxiliary link 153, thereby helping to better assist the leg support unit 130 in unfolding. The cross-sectional shape of the seat frame 120 along the length direction is approximately right-angled. In a preferred embodiment, the top side of the seat frame 120 is provided with a clearance groove 123 at the hinge point corresponding to the upper end of the auxiliary swing rod 152 and the rear end of the auxiliary connecting rod 153. The clearance groove 123 extends a certain length along the length direction of the seat frame 120. The hinge point between the upper end of the auxiliary swing rod 152 and the rear end of the auxiliary connecting rod 153 can extend upward from the clearance groove 123 into the seat frame 120. By utilizing the clearance groove 123, the movement space of the auxiliary swing rod 152 and the auxiliary connecting rod 153 can be appropriately increased without increasing the external dimensions of the seat frame 120. This allows for an appropriate increase in the length of the auxiliary swing rod 152, enabling the rear end of the auxiliary connecting rod 153 to be further away from the swing fulcrum of the auxiliary swing rod 152. This helps to further increase the torque applied by the tension spring 151 to the auxiliary connecting rod 153 through the auxiliary swing rod 152, thereby further improving the effect of the tension spring 151 in pulling the leg support unit 130 forward. In an alternative embodiment, the clearance groove 123 on the seat frame 120 can also be omitted, and the hinge portion between the upper end of the auxiliary swing arm 152 and the rear end of the auxiliary connecting rod 153 is always lower than the top side of the seat frame 120 to avoid the hinge portion hitting the seat frame 120.

[0062] In this embodiment, the lower end of the auxiliary swing rod 152 is provided with a lug 1521 protruding towards the center of the device. The front end of the tension spring 151 directly or indirectly hooks onto the lug 1521 to achieve connection to the swinging end of the auxiliary swing rod 152. Of course, the cooperation method between the front end of the tension spring 151 and the auxiliary swing rod 152 is not limited to what is described above and shown in the figures. Other reasonable cooperation methods can also be used to ensure that the front end of the tension spring 151 and the swinging end of the auxiliary swing rod 152 can maintain a stable connection.

[0063] In this embodiment, the rear end of the base frame 110 is provided with an upwardly protruding tongue 111, and the rear end of the tension spring 151 directly or indirectly hooks onto the tongue 111 to achieve positioning. A reasonable design of the connection structure at the rear end of the tension spring 151 ensures the positioning stability of the rear end of the tension spring 151 while simplifying the structure that mates with the rear end of the tension spring 151, and also helps reduce the assembly difficulty of the tension spring 151. In other solutions of this embodiment, the rear end of the tension spring 151 can also be connected to the rear end of the base frame 110 via screws or other connecting parts to achieve positioning; or, the third support rod 230 of the support assembly 200 can be provided with a tongue located behind the auxiliary swing rod 152, and the rear end of the tension spring 151 directly or indirectly hooks onto the tongue on the third support rod 230 to achieve positioning; or, the rear end of the tension spring 151 can also be connected to the third support rod 230 of the support assembly 200 via screws or other connecting parts to achieve positioning. Since the third support rod 230 is located behind the auxiliary swing rod 152, the rear end of the tension spring 151 can be kept as far away from the auxiliary swing rod 152 as possible. Of course, the positioning method of the rear end of the tension spring 151 is not limited to what is described above or shown in the attached figure. Other reasonable methods can also be used to keep the rear end of the tension spring 151 relatively stable.

[0064] In this embodiment, the tension spring 151, the auxiliary swing rod 152, and the auxiliary connecting rod 153 are located on the inner side of the seat frame 120 facing the center of the device, while the swing mechanism 160 is located on the outer side of the seat frame 120 facing away from the center of the device. That is, the tension spring 151 and the swing mechanism 160 are located on opposite sides of the seat frame 120. The reasonable arrangement of the swing mechanism 160 and the tension spring 151 relative to the seat frame 120 avoids interference between the tension spring 151 and the swing mechanism 160, ensuring that their respective functions are not affected by the other, thereby ensuring the smoothness and stability of the device when the whole device switches postures. Furthermore, in order to enable the auxiliary swing rod 152 to connect with the follower frame 161 of the swing mechanism 160, the auxiliary swing rod 152 is bent so that its lower end can slightly touch the follower frame 161, which helps to improve the stability of the auxiliary swing rod 152 hinged to the follower frame 161.

[0065] In this embodiment, since the follower frame 161 is connected to the seat frame 120 and the first support rod 210 and the second support rod 220 are connected to the follower frame 161, when the device switches postures, the seat frame 120 will also drive the first support rod 210 and the second support rod 220 to move. Based on this, the tension spring 151 is located longitudinally between the upper surface of the seat frame 120 and the support assembly 200. Specifically, the rear end of the tension spring 151 is set higher than or flush with the third support rod 230. The lower end of the auxiliary swing rod 152 is always higher than the front protrusion 1611 and the rear protrusion 1612 of the follower frame 161, so as to avoid the support assembly 200 from interfering with the reciprocating swing of the auxiliary swing rod 152 and the extension and retraction of the tension spring 151. This ensures that the tension spring 151 is always higher than the first support rod 210 and the second support rod 220 of the support assembly 200, and also ensures that the tension spring 151, the auxiliary swing rod 152 and the auxiliary connecting rod 153 will not affect the original structural layout of the device, which is conducive to keeping the overall structure of the device compact.

[0066] Combination Figure 9 In this embodiment, the base frame 110 has a first swing stop pin 1671 for limiting the swing amplitude of the first rod 1641 and a second swing stop pin 1672 for limiting the swing amplitude of the third rod 1651 on the side facing the swing mechanism 160. The first swing stop pin 1671 is a single pin located behind the lower end of the first rod 1641, and the second swing stop pins 1672 are two pins located on the front and rear sides of the lower end of the third rod 1651, respectively. The first rod 1641 can be stabilized by contacting the first swing stop pin 1671, thereby ensuring the structural stability of the front retaining unit 164. The third rod 1651 can be stabilized by contacting one of the second swing stop pins 1672, thereby ensuring the structural stability of the rear retaining unit 165. Therefore, the first swing stop pin 1671 and the second swing stop pin 1672 can keep the front retaining unit 164 and the rear retaining unit 165 in a stable state. Additionally, the follower frame 161 has a third swing stop pin 1673 on the side facing the center of the device to limit the swing amplitude of the driven swing rod 166. There are two third swing stop pins 1673, located on the front and rear sides of the lower end of the driven swing rod 166, respectively. When the driven swing rod 166 contacts either of the third swing stop pins 1673, the driven swing rod 166 is limited and cannot swing, thus keeping the seat frame 120 relatively stable. The combination of the first swing stop pin 1671, the second swing stop pin 1672, and the third swing stop pin 1673 allows the relevant components of the swing mechanism 160 to maintain a stable position when the device is in a certain posture, thereby ensuring the stability of the swing mechanism 160 and the seat frame 120, and ultimately maintaining the overall posture of the device.

[0067] Combination Figure 4 , Figure 10 , Figure 11In this embodiment, the backrest unit 140 includes a backrest frame 141, a linkage structure, and several limiting pins. The backrest frame 141 is movably connected to the rear end of the seat frame 120 through the linkage structure. The seat frame 120, driven by the leg support unit 130, can drive the backrest frame 141 to move through the linkage structure so that the state of the backrest unit 140 adapts to the posture of the mechanical extension device 10. The various states of the backrest unit 140 are limited by several limiting pins.

[0068] In this embodiment, in order to avoid interference between the tension spring 151 and the backrest unit 140, the linkage structure of the backrest unit 140 is located on the outer side of the rear end of the seat frame 120. That is, the linkage structure of the tension spring 151 and the backrest unit 140 are respectively located on the inner and outer sides of the seat frame 120 to avoid interference between the two and ensure that their respective functions are not affected by the other, thereby ensuring the smoothness and stability of the device when the whole device switches postures.

[0069] In this embodiment, the rear end of the seat frame 120 is fixed with an extension plate 121 by riveting or other means. The linkage structure includes a follower link 142, a follower swing arm 143, a front backrest link 144, a rear backrest link 145, and a middle link 146. The upper end of the front backrest link 144 is hinged to the front side of the lower end of the backrest frame plate 141, and the lower end of the front backrest link 144 is hinged to the rear end of the seat frame 120. The upper end of the rear backrest link 145 is hinged to the rear side of the lower end of the backrest frame plate 141, and the lower end of the rear backrest link 145 is hinged to the extension plate 121. The follower link 142 is rotatably hinged to the extension plate 121 at approximately its middle portion. One end of the follower link 142 is hinged to one end of the follower swing arm 143, and the other end is hinged to one end of the intermediate link 146. The other end of the follower swing arm 143 is hinged to the base frame 110, and the other end of the intermediate link 146 is hinged to the front backrest link 144. Preferably, the lower ends of the follower link 142 and the backrest link 145 are both hinged to the same position on the extension plate 121, that is, the hinge point between the follower link 142 and the extension plate 121 coincides with the hinge point between the lower end of the backrest link 145 and the extension plate 121. Furthermore, the hinge point between the intermediate link 146 and the front backrest link 144 is offset from the hinge point between the front backrest link 144 and the backrest frame plate 141. Figure 12 In this embodiment, the front backrest link 144 is preferably a V-shaped link with a corner portion 1441, and the other end of the middle link 146 is hinged to the corner portion 1441 of the front backrest link 144. In other embodiments of this embodiment, the extension plate 121 can be integrally formed with the seat frame 120.

[0070] In this embodiment, the limiting pins include a first limiting pin 1481 disposed on the backrest frame 141, a second limiting pin 1482 disposed on the linkage structure, and a third limiting pin 1483 disposed on the seat frame 120. The first limiting pin 1481 cooperates with the linkage structure to limit the swing amplitude of the backrest frame 141, and the second limiting pin 1482 and the third limiting pin 1483 both cooperate with the linkage structure to limit the movement amplitude of the linkage structure.

[0071] Specifically, the first limiting pin 1481 is located at the lower part of the backrest frame 141. The first limiting pin 1481 is located not only between the upper end of the front backrest link 144 and the upper end of the backrest link 145 in the front-back direction, but also between the upper end of the front backrest link 144 and the upper end of the backrest link 145 in the vertical direction. The upper end of the backrest link 145 is slightly higher than the upper end of the front backrest link 144. The first limiting pin 1481 can abut against the front backrest link 144 to limit the range of backward swing of the backrest frame 141.

[0072] In this embodiment, the second limiting pin 1482 is disposed on the front backrest link 144. Preferably, the second limiting pin 1482 is located on the front backrest link 144 between the hinge between the intermediate link 146 and the front backrest link 144 and between the front backrest link 144 and the seat frame 120. The second limiting pin 1482 can abut against the follower link 142 to limit the front backrest link 144. The third limiting pin 1483 is disposed at the rear end of the seat frame 120 and located on the front side of the lower end of the front backrest link 144. The front backrest link 144 can abut against the third limiting pin 1483 to achieve limitation. The second limiting pin 1482 and the third limiting pin 1483 can be combined to limit the movement range of the front backrest link 144 and can keep the linkage structure stably in a certain state.

[0073] In this embodiment, the extension plate 121 is preferably located on the outer side of the seat frame 120, and the extension plate 121 is located on the rear side of the lower end of the backrest front link 144. In addition, the backrest frame plate 141 is set higher than the seat frame 120, so that the backrest frame plate 141 can swing smoothly relative to the seat frame 120.

[0074] Furthermore, the front backrest link 144 and the rear backrest link 145 are located outside the backrest frame 141, the follower link 142 is located outside the front backrest link 144 and the rear backrest link 145, the intermediate link 146 is located outside the follower link 142 and the front backrest link 144, and the follower swing arm 143 is located between the follower link 142 and the base frame 110. This reasonable arrangement of the relative positions of the components in the linkage structure improves the smoothness of the linkage structure's movement and avoids interference between components that could prevent the linkage structure from moving smoothly. Of course, the positional relationships of the components in the linkage structure are not limited to those described above and in the accompanying drawings; other positional distribution methods that satisfy the need to move the backrest frame 141 can also be used.

[0075] Combination Figure 13 In this embodiment, the mechanical extension device 10 corresponds to three sequentially arranged postures of the functional sofa: a sitting posture (hereinafter referred to as sitting posture), a TV posture (hereinafter referred to as TV posture), and a reclining posture (hereinafter referred to as reclining posture). Furthermore, the extension device 10 has an unfolding stage and a return stage, with the return stage being the reverse of the unfolding stage. During the unfolding stage, the mechanical extension device 10 can unfold from the sitting posture to the TV posture or the reclining posture, or further unfold from the TV posture to the reclining posture. During the return stage, the mechanical extension device 10 can return from the reclining posture to the TV posture or directly back to the sitting posture, or return from the TV posture to the sitting posture. In other embodiments of this embodiment, the mechanical extension device 10 may only be configured with sitting and reclining postures. Of course, the mechanical extension device 10 may also be configured with more postures, such as a reading posture between the sitting and TV postures, or a semi-reclining posture between the TV and reclining postures. This embodiment does not specifically limit the postures of the mechanical extension device 10.

[0076] This embodiment uses the mechanical extension device 10 having sitting, TV, and lying positions as examples for specific explanation. Combined with... Figure 14When the mechanical extension device 10 is in a sitting position, the leg support unit 130 is in a retracted state, the seat frame 120 is in a rearward state, the swing mechanism 160 is in a first holding state, the backrest frame 141 of the backrest unit 140 is in an inclined state, and the linkage structure of the backrest unit 140 is in a first associated state that keeps the backrest frame 141 in an inclined state. At this time, the first retractable stop pin 1381 abuts against the seat frame 120 and the second retractable stop pin 1382 abuts against the leg rest rear connecting rod 134; the driven swing rod 166 abuts against the rear third swing stop pin 1673, keeping the seat frame 120 in a rearward position; the first rod 1641 of the front holding unit 164 abuts against the first swing stop pin 1671, and the third rod 1651 of the rear holding unit 165 abuts against the rear second swing stop pin 1672, thereby keeping the swing mechanism 160 in the first holding state; the first limiting stop pin 1481 on the backrest frame 141 separates from the backrest front connecting rod 144, and the second limiting stop pin 1482 on the backrest front connecting rod 144 abuts against the top side of the follower connecting rod 142, keeping the linkage structure in the first connection. In the first associated state, the backrest front link 144 is limited and cannot swing due to the contact between the second limiting pin 1482 and the follower link 142, thereby limiting the backrest frame 141 and keeping it in an inclined position. At the same time, when the linkage structure is in the first associated state, the backrest front link 144 can abut against the front side of the extension plate 121. The contact with the extension plate 121 further improves the positional stability of the backrest front link 144 when the linkage structure is in the first associated state. This allows the backrest frame 141 in the inclined position to remain stable even when subjected to a large force, preventing the backrest frame 141 in the inclined position from suddenly tilting backward due to the large force it bears.

[0077] During the transition from a seated to a TV position, the drive assembly 300 causes the leg support unit 130 to extend forward from a retracted state to an extended state. Simultaneously, the extended leg support unit 130 drives the seat frame 120 to move forward relative to the swing mechanism 160. Figure 15When the mechanical extension device 10 switches to the TV posture, the leg support unit 130 is in the extended state, the seat frame 120 is in the forward state, the swing mechanism 160 is still in the first holding state, the backrest frame 141 of the backrest unit 140 is still in the inclined state, and the linkage structure of the backrest unit 140 is still in the first associated state. At this time, the extension stop pin 1383 abuts against the front swing rod 131 of the leg support, limiting the extension range of the leg support unit 130 and making the leg support unit 130 stable in the extended state; the seat frame 120, which moves from the rearward state to the forward state, drives the driven swing rod 166 to swing forward until it abuts against the third swing stop pin 1673 on the front side. The third swing stop pin 1673 limits the swing range of the driven swing rod 166 and makes the driven swing rod 166 stable in position, thereby keeping the seat frame 120 in the forward state; the first... One rod 1641 still abuts against the first swing stop pin 1671, and the third rod 1651 of the rear holding unit 165 still abuts against the second swing stop pin 1672 on the rear side, thereby keeping the swing mechanism 160 in the first holding state; the second limiting stop pin 1482 on the backrest front link 144 abuts against the top side of the follower link 142 to keep the linkage structure in the first associated state. The linkage structure in the first associated state keeps the backrest frame 141 in an inclined position, and the backrest front link 144 can still abut against the front side of the extension plate 121 at this time.

[0078] During the transition from a TV position to a reclining position, the drive assembly 300 drives the extended leg support unit 130 to move diagonally upwards. The leg support unit 130, through the seat frame 120, drives the swing mechanism 160 and the backrest unit 140 to move. Figure 16When the mechanical extension device 10 switches to a reclining position, the leg support unit 130 remains in the extended state, the seat frame 120 remains in the forward position, the swing mechanism 160 switches from the first holding state to the second holding state, the backrest frame 141 of the backrest unit 140 switches from the inclined state to the reclining state, and the linkage structure of the backrest unit 140 switches from the first linkage state to the second linkage state. At this time, the unfolding stop pin 1383 abuts against the leg rest front swing rod 131, allowing the leg rest unit 130 to remain stably in the unfolded state; the driven swing rod 166 still abuts against the front third swing stop pin 1673, keeping the seat frame 120 in the forward position; the swing mechanism 160, switching from the first holding state to the second holding state, causes the first rod 1641 to swing forward and separate from the first swing stop pin 1671, and causes the third rod 1651 to swing forward until it abuts against the front second swing stop pin 1672. The abutment between the third rod 1651 and the front second swing stop pin 1672 allows the swing mechanism 160 to remain stably in the second holding state; the seat frame 120 drives the backrest unit 140 to move, causing the linkage structure to move from the first... When switching from the first associated state to the second associated state, the linkage structure causes the backrest frame 141 to switch from an inclined position to a reclining position. When the backrest frame 141 is in the reclining position, the first limiting pin 1481 abuts against the top side of the V-shaped upper end of the front backrest link 144. The backrest frame 141 is kept in the reclining position by the contact between the first limiting pin 1481 and the front backrest link 144. When switching to the second associated state, the linkage structure causes the front backrest link 144 to swing to contact the third limiting pin 1483 on the seat frame 120. The linkage structure is kept in the second associated state by the contact between the front backrest link 144 and the third limiting pin 1483.

[0079] When the mechanical extension device 10 switches from a reclining position to a TV position, the leg support unit 130 remains in the extended state, the seat frame 120 remains in the forward position, the swing mechanism 160 switches from the second holding state to the first holding state, and the linkage structure of the backrest unit 140 switches from the second associated state to the first associated state and drives the backrest frame 141 to switch from the reclining state to the inclined state.

[0080] When the mechanical extension device 10 switches from the TV posture to the sitting posture, the leg support unit 130 resets from the unfolded state to the retracted state, the seat frame 120 resets from the forward state to the rearward state, the swing mechanism 160 remains in the first holding state, the linkage structure of the backrest unit 140 is in the first associated state, and the backrest frame 141 is in the inclined state.

[0081] When the mechanical extension device 10 switches directly from a lying position to a sitting position, the leg support unit 130 returns from the unfolded state to the folded state, the seat frame 120 switches from the rearward state to the forward state, the swing mechanism 160 switches from the second holding state to the first holding state, and the linkage structure of the backrest unit 140 switches from the second associated state to the first associated state and drives the backrest frame 141 to switch from the reclining state to the inclined state.

[0082] The various states of the backrest unit 140 are restricted by three limiting pins. The mechanical rigidity of these pins ensures that the backrest unit 140 remains stably in a specific posture, guaranteeing the overall structural stability of the device and preventing it from tilting backward when the user is sitting or reclining. Furthermore, the limiting pins prevent excessive movement of the backrest unit 140 components, avoiding situations where components exceed safe positions and become difficult to reset. Moreover, the combination of the limiting pins and components provides strong load-bearing capacity for maintaining the backrest unit 140's stable state, increasing its load-bearing capacity. In short, the limiting pins meet the requirement of structural stability for the backrest unit 140; they are also simple in structure, low in cost, and easy to assemble and maintain.

[0083] The functional sofa has a backrest 20 corresponding to the backrest unit 140. The backrest 20 includes components such as a back panel structure, an outer fabric, and filling. The back panel structure of the backrest 20 can be connected to the backrest frame 141 so that the backrest 20 can move synchronously when the backrest unit 140 swings backward to recline or swings forward to stand up. The outer fabric of the backrest 20 can be made of materials such as cotton, linen, genuine leather, or artificial leather. The filling of the backrest 20 can be made of a single material or a mixture of materials such as down, sponge, wool, or cotton. No specific limitations are made here regarding the outer fabric and filling of the backrest 20.

[0084] When the mechanical extension device 10 is in a seated position, the leg support unit 130 is folded and retracted to the bottom of the seat frame 120. The tension spring 151 always applies a forward traction force to the rear swing arm 132 of the leg support through the auxiliary swing arm 152 and the auxiliary connecting rod 153, that is, the tension spring 151 always applies a forward traction force to the leg support unit 130. Since the tension spring 151 applies a backward pulling force to the lower end of the auxiliary swing arm 152, and since the auxiliary swing arm 152 is hinged to the follower frame 161 of the swing mechanism 160, the tension spring 151 applies a backward force to the swing mechanism 160 through the auxiliary swing arm 152, that is, the tension spring 151 applies an extension resistance to the swing mechanism 160, thereby making the swing mechanism 160 structurally stable when the device is in a seated position.

[0085] When the mechanical extension device 10 switches from a sitting position to a TV position, the drive member 310 of the drive assembly 300 drives the drive rod 320 to move diagonally upward and forward. The drive rod 320 drives the leg support unit 130 to extend forward via the leg support front swing rod 131. During this process, the tension spring 151 applies a forward auxiliary force to the leg support unit 130, and at the same time, the tension spring 151 applies a backward resistance to the swing mechanism 160. The forward-extended leg support unit 130 drives the seat frame 120 to move from a rearward position to a forward position. The forward-moving seat frame 120 drives the backrest unit 140 to move forward and swing backward at a small angle. During this switching process, the distance the backrest unit 140 moves forward relative to the sitting position is greater than the distance required for the backrest unit 140 to swing backward, thus allowing the functional sofa to smoothly switch to a TV position even when the sitting position is against the wall.

[0086] When the mechanical extension device 10 switches from the TV position to the reclining position, the drive component 310 of the drive assembly 300 drives the drive rod 320 to move diagonally upward and forward. The drive rod 320, through the leg support unit 130, drives the seat frame 120 to move diagonally upward and forward a certain distance. The seat frame 120 drives the backrest unit 140 to move forward and swing backward, allowing the backrest unit 140 to recline. During this switching process, the distance the backrest unit 140 moves forward relative to the TV position is greater than the distance required for the backrest unit 140 to swing backward and recline, thus allowing the functional sofa to smoothly switch to the reclining position even when it is in a sitting position against the wall. When the device switches to the reclining position, the top side of the backrest 20 and the front end of the leg support unit 130 are approximately at the same height, so when the user lies down, the legs and heart are approximately at the same height.

[0087] When the mechanical extension device 10 switches from a lying position to a TV position or a sitting position, or from a TV position to a sitting position, the tension spring 151 always applies a forward traction force to the leg support rear swing arm 132 and simultaneously applies a backward force to the swing mechanism 160. During the return phase, the tension spring 151 assists the swing mechanism 160 in driving the seat frame 120 back to its original position, so that the leg support unit 130 retracts after the seat frame 120 returns to its original position, which helps to improve the smoothness of the device's movement during the return phase.

[0088] The first swing stop pin 1671, the second swing stop pin 1672, and the third swing stop pin 1673 can adopt a pin-and-sleeve structure, with the pin passing through the base frame 110 and the sleeve sleeve fitted onto the pin. The lower ends of the first rod 1641, the third rod 1651, and the follower swing rod 143 can all be hinged to the base frame 110 via pins or other connecting parts. To ensure the structural strength of the components connected to the base frame 110, preferably, the outer side of the base frame 110 is provided with several recesses 112 corresponding to the connection positions of the components. The recesses 112 prevent the head of the pin in each swing stop pin from protruding from the outer surface of the base frame 110, and also prevent the head of the connecting part that hinges the components to the base frame 110 from protruding from the outer surface of the base frame 110. This avoids the swing stop pins or connecting parts on the base frame 110 from being subjected to external impacts, ensuring the structural stability of each swing stop pin and the structural stability of the components hinged to the base frame 110 via connecting parts.

[0089] In other embodiments, when the mechanical extension device 10 is in the TV position, the seat frame 120 can also be in a rearward position. In this case, the driven rocker arm 166 abuts against the third swing stop pin 1673 on the rear side to keep the seat frame 120 in the rearward position. When the mechanical extension device 10 switches from the TV position to the reclining position, the seat frame 120 switches from the rearward position to the forward position, and the driven rocker arm 166 abuts against the third swing stop pin 1673 on the front side to keep the seat frame in the forward position.

[0090] In other embodiments, the base frame 110 may also be driven by other mechanisms.

[0091] In other embodiments, the auxiliary link 153 may be omitted. In this case, the upper end of the auxiliary swing arm 152 is directly hinged to the front swing arm 131 and / or the rear swing arm 132 of the leg support unit 130.

[0092] In other embodiments, the tension spring 151, auxiliary link 153, and auxiliary swing arm 152 may be omitted.

[0093] In other embodiments, the backrest unit 140 may also employ other methods to maintain a stable state when the device is in different postures.

[0094] In addition to the preferred embodiments described above, there are other embodiments of this utility model. Those skilled in the art can make various changes and modifications based on this utility model. As long as they do not depart from the spirit of this utility model, they should all fall within the scope defined in the claims of this utility model.

Claims

1. A mechanical extension device for a functional sofa, comprising: The extension assembly has two sets arranged symmetrically on the left and right sides; A support assembly is located between two sets of extension assemblies and is used to connect the two sets of extension assemblies. A drive assembly is located between two sets of extension assemblies and is used to drive the two sets of extension assemblies to move synchronously to switch the posture of the mechanical extension device. The extension assembly includes a base frame, a seat frame, a swing mechanism, a leg support unit, and a backrest unit. The seat frame is movably mounted on the base frame via the swing mechanism. The leg support unit is located at the front end of the seat frame, and the backrest unit is located at the rear end of the seat frame. The drive assembly can drive the leg support unit to extend forward or retract backward relative to the seat frame. The driven leg support unit can drive the backrest unit to move through the seat frame. The extension assembly is characterized in that it further includes an auxiliary swing arm and a tension spring. The auxiliary swing arm is hinged to the swing mechanism and can swing back and forth longitudinally relative to the swing mechanism. The rear end of the tension spring is positioned and the front end of the tension spring is connected to one swing end of the auxiliary swing arm. The other swing end of the auxiliary swing arm is hinged to the seat frame and connected to the leg support unit. The tension spring pulls the leg support unit forward through the auxiliary swing arm to assist the drive assembly in driving the leg support unit to extend forward.

2. The mechanical extension device for a functional sofa according to claim 1, characterized in that, An auxiliary link is provided between the auxiliary swing arm and the leg support unit. The rear end of the auxiliary link is hinged to the other end of the swing arm, and the front end of the auxiliary link is connected to the leg support unit. The tension spring applies a forward traction force to the leg support unit through the auxiliary swing arm and the auxiliary link.

3. A mechanical extension device for a functional sofa according to claim 2, characterized in that, The hinge point between the rear end of the auxiliary link and the auxiliary swing arm is located further away from the hinge point between the auxiliary swing arm and the seat frame than the hinge point between the auxiliary swing arm and the swing mechanism.

4. A mechanical extension device for a functional sofa according to claim 3, characterized in that, The front end of the tension spring is connected to the lower end of the auxiliary swing arm, and the rear end of the auxiliary connecting rod is hinged to the upper end of the auxiliary swing arm. The seat frame is provided with a clearance groove corresponding to the hinge part between the upper end of the auxiliary swing arm and the rear end of the auxiliary connecting rod.

5. A mechanical extension device for a functional sofa according to claim 1, characterized in that, The seat frame has a downwardly extending protrusion corresponding to the auxiliary swing arm, and the auxiliary swing arm is hinged to the protrusion of the seat frame.

6. A mechanical extension device for a functional sofa according to claim 2, characterized in that, The leg support unit includes a front leg support swing arm, a rear leg support swing arm, a front leg support connecting rod, a rear leg support connecting rod, and a main leg support frame plate. The rear ends of the front and rear leg support swing arms are hinged to the front end of the seat frame, staggered from one end to the other. One end of the front leg support connecting rod is hinged to the front end of the front leg support swing arm and the other end is hinged to the main leg support frame plate. The rear leg support connecting rod is hinged to the front leg support connecting rod, with one end hinged to the front end of the rear leg support swing arm and the other end hinged to the main leg support frame plate. The front end of the auxiliary connecting rod is hinged to the front and / or rear leg support swing arms. A tension spring applies a forward traction force to the front and / or rear leg support swing arms of the leg support unit through the auxiliary swing arm and the auxiliary connecting rod.

7. A mechanical extension device for a functional sofa according to claim 6, characterized in that, The drive assembly includes a drive member and a drive rod driven by the drive member. The two ends of the drive rod are respectively fixedly connected to the front swing arm of the leg support unit in the two sets of extension assemblies, and the front end of the auxiliary link is hinged to the rear swing arm of the leg support unit.

8. A mechanical extension device for a functional sofa according to claim 7, characterized in that, The drive component includes a motor part and a telescopic push rod part. The push rod part has a fixed end and a free end. The fixed end of the push rod part is fixedly connected to the motor part, and the free end of the push rod part is hinged to the support assembly. The motor part is rotatably connected to the drive rod.

9. A mechanical extension device for a functional sofa according to claim 6, characterized in that, The leg support unit also includes an unfolding stop pin disposed on the rear connecting rod of the leg support and corresponding to the front swing rod of the leg support. The leg support unit has an unfolded state. When the leg support unit is switched to the unfolded state, the unfolding stop pin abuts against the front swing rod of the leg support.

10. A mechanical extension device for a functional sofa according to claim 6, characterized in that, The leg support unit further includes a first retractable stop pin disposed on the rear swing arm of the leg support. The leg support unit has a retracted state. When the leg support unit is switched to the retracted state, the first retractable stop pin abuts against the seat frame. And / or, the leg support unit further includes a second retractable stop pin disposed on the main frame plate of the leg support. The leg support unit has a retracted state. When the leg support unit is switched to the retracted state, the second retractable stop pin abuts against the rear connecting rod of the leg support.

11. A mechanical extension device for a functional sofa according to claim 1, characterized in that, The swing mechanism includes a follower frame, an intermediate frame, an auxiliary frame, a front holding unit, and a rear holding unit. The follower frame is connected to the support assembly. The auxiliary swing rod is hinged to the front end of the follower frame. The rear end of the follower frame is movably connected to the seat frame via a driven swing rod. The front holding unit includes a first rod and a second rod. The lower end of the first rod is hinged to the base frame, and the upper end is hinged to the front end of the auxiliary frame. The front end of the follower frame, the front end of the intermediate frame, and the upper part of the first rod are hinged to different positions of the second rod. The rear end of the intermediate frame is hinged to the auxiliary frame. The rear holding unit includes a third rod and a fourth rod. The lower end of the third rod is hinged to the base frame. The rear end of the follower frame, the rear end of the auxiliary frame, and the upper end of the third rod are hinged to different positions of the fourth rod.

12. A mechanical extension device for a functional sofa according to claim 11, characterized in that, The base frame is provided with a first swing stop pin for limiting the swing amplitude of the first rod and / or a second swing stop pin for limiting the swing amplitude of the third rod.

13. A mechanical extension device for a functional sofa according to claim 12, characterized in that, The base frame is provided with a first swing stop pin for limiting the swing amplitude of the first rod. The first swing stop pin is provided and located on the rear side of the lower end of the first rod. The mechanical extension device has at least a sitting posture and a lying posture. The swing mechanism has a first holding state corresponding to the sitting posture of the mechanical extension device and a second holding state corresponding to the lying posture of the mechanical extension device. When the swing mechanism is in the first holding state, the first rod abuts against the first swing stop pin. When the swing mechanism switches from the first holding state to the second holding state, the first rod swings forward and separates from the first swing stop pin.

14. A mechanical extension device for a functional sofa according to claim 12, characterized in that, The base frame is provided with a second swing stop pin for limiting the swing amplitude of the third rod. There are two second swing stop pins, which are respectively located on the front and rear sides of the lower end of the third rod. The mechanical extension device has at least a sitting posture and a lying posture. The swing mechanism has a first holding state corresponding to the sitting posture of the mechanical extension device and a second holding state corresponding to the lying posture of the mechanical extension device. When the swing mechanism is in the first holding state, the third rod abuts against the second swing stop pin on the rear side. When the swing mechanism switches from the first holding state to the second holding state, the third rod swings forward until it abuts against the second swing stop pin on the front side.

15. A mechanical extension device for a functional sofa according to claim 11, characterized in that, The follower frame is provided with a third swing stop pin corresponding to the driven swing arm. There are two third swing stop pins, which are respectively located on the front and rear sides of the lower end of the driven swing arm. The seat frame has a rearward state and a forward state corresponding to different postures of the mechanical extension device. When the seat frame is in the rearward state, the driven swing arm abuts against the third swing stop pin on the rear side. When the seat frame switches from the rearward state to the forward state, it drives the driven swing arm to swing forward until it abuts against the third swing stop pin on the front side.

16. A mechanical extension device for a functional sofa according to claim 11, characterized in that, The outer side of the base frame is provided with several recessed grooves for avoidance at each connection position.

17. A mechanical extension device for a functional sofa according to claim 1, characterized in that, The tension spring is located longitudinally between the upper surface of the seat frame and the support assembly.

18. A mechanical extension device for a functional sofa according to claim 1, characterized in that, The base frame has an upwardly protruding tongue at its rear end, and the rear end of the tension spring is hooked onto the tongue for positioning; or, the support assembly has a tongue located behind the auxiliary swing arm, and the rear end of the tension spring is hooked onto the tongue for positioning; or, the rear end of the tension spring is connected to the rear end of the base frame via a connector; or, the rear end of the tension spring is connected to a position in the support assembly located behind the auxiliary swing arm via a connector.

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