Mechanical stretching device for movable seat unit and seat unit

Abstract

The present disclosure relates to a movable seat with a mechanical stretching device. The movable seat includes a frame assembly connected to the mechanical stretching device and the frame assembly includes a seat frame configured to support a seating portion of the movable seat, an armrest frame fixedly connected to the seat frame, and a backrest frame configured to support a backrest of the movable seat, where the backrest frame includes a lower frame section and an upper frame section, the upper frame section transitions to the lower section via a stepped portion, and a rear part of the armrest frame includes a curved extending section, and a gap is formed between the armrest frame and the upper frame section.

What is claimed is: 
     
         1 . A movable seat, comprising:
 a mechanical stretching device; and   a frame assembly connected to the mechanical stretching device, wherein the frame assembly comprises:   a seat frame configured to support a seating portion of the movable seat;   an armrest frame fixedly connected to the seat frame; and   a backrest frame configured to support a backrest of the movable seat, wherein the backrest frame comprises a lower frame section and an upper frame section, the upper frame section transitions to the lower section via a stepped portion, and a rear part of the armrest frame comprises a curved extending section, and a gap is formed between the armrest frame and the upper frame section.   
     
     
         2 . The movable seat according to  claim 1 , wherein the stepped portion comprises a lower edge that extends in a substantially arcuate shape. 
     
     
         3 . The movable seat according to  claim 1 , wherein the mechanical stretching device comprises:
 a base assembly fixedly supported on a ground;   a side plate movably supported above the base assembly, wherein the side plate is configured to connect to the seating portion of the movable seat; and   a backrest assembly pivotally connected to a rear portion of the side plate,   wherein in a transition of the movable seat from one position to another position, the backrest assembly moves forward along with the side plate and the gap between the armrest frame and the upper frame section remains substantially unchanged.   
     
     
         4 . The movable seat according to  claim 1 , wherein a gap is formed between the lower frame section and the seat frame, and wherein in a transition of the movable seat from one position to another position, the gap between the lower frame section and the seat frame remains substantially unchanged. 
     
     
         5 . The movable seat according to  claim 3 ,
 wherein the backrest assembly pivotally connected to a rear portion of the side plate, wherein the backrest assembly comprises a backrest mounting member and a backrest connecting rod assembly;   wherein the mechanical stretching device further comprises a central coupling element movably connected between the side plate and the backrest assembly;   wherein the backrest connecting rod assembly comprises a first backrest connecting rod and a second backrest connecting rod, an upper end of the first backrest connecting rod is hinged to a front end of the backrest mounting member at a first pivot point, a front end portion of the second backrest connecting rod is hinged to the side plate at a second pivot point, and a middle portion of the second backrest connecting rod is hinged to a middle portion of the first backrest connecting rod.   
     
     
         6 . The movable seat according to  claim 5 ,
 wherein the mechanical stretching device further comprises a leg stretching device pivotally connected to a front portion of the side plate, wherein the leg stretching device comprises a first footrest element configured to attach a footrest;   wherein the mechanical stretching device transitions at least between a sitting position and a lying position,   wherein in the sitting position, the first footrest element is retracted beneath the seating portion;   wherein in the lying position, the backrest of the movable seat is reclined and the first footrest element is extended forward relative to the sitting position; and   wherein a distance between the first pivot point and the second pivot point is reduced in the lying position compared to the sitting position.   
     
     
         7 . The movable seat according to  claim 6 , wherein relative movement between the central coupling element and the side plate drives the backrest connecting rod assembly to compress and expand so that the backrest mounting member rotates rearward and forward about the first pivot point. 
     
     
         8 . The movable seat according to  claim 7 ,
 wherein the backrest connecting rod assembly further comprises a third backrest connecting rod, wherein a lower end of the first backrest connecting rod is hinged to the central coupling element at a third pivot point, an upper end of the third backrest connecting rod is hinged to a rear end of the backrest mounting member, and a lower end of the third backrest connecting rod is hinged to a rear end of the second backrest connecting rod.   
     
     
         9 . The movable seat according to  claim 8 , wherein in transition of the movable seat from the sitting position to the lying position, relative movement between the side plate and the central coupling element increases a distance between the second pivot point and the third pivot point and compresses the backrest connecting rod assembly. 
     
     
         10 . The movable seat according to  claim 6 , wherein the leg stretching device further comprises a second footrest element,
 wherein in the sitting position, both the first footrest element and the second footrest element are retracted beneath the seating portion; and   wherein in the lying position, the backrest is reclined, and a highest point of the footrest is higher than a highest point of the backrest, wherein both the first footrest element and the second footrest element extend forward and upward, and the second footrest element is positioned in front of the first footrest element.   
     
     
         11 . The movable seat according to  claim 10 , wherein the first footrest element and the second footrest element are connected via a footrest connection element, wherein the footrest connection element comprises a first connecting element and a second connecting element that are hinged to each other. 
     
     
         12 . The movable seat according to  claim 3 , wherein the mechanical stretching device further comprises a front swing rod, a rear swing rod, a seat coupling element, and a side plate coupling element, wherein lower ends of the front swing rod and the rear swing rod are pivotally connected to the base assembly, and upper ends of the front swing rod and the rear swing rod are connected to the side plate via the central coupling element, the seat coupling element, and the side plate coupling element, and
 wherein movement of the side plate relative to the base assembly drives movement of the backrest assembly and the leg stretching device relative to the side plate, and enables the movable seat to transit between the sitting position and the lying position.   
     
     
         13 . The movable seat according to  claim 6 , wherein in the lying position, a highest point of the first footrest element is higher than a highest point of the backrest mounting member. 
     
     
         14 . The movable seat according to  claim 3 , wherein the mechanical stretching device further comprises: an electric driving device coupled between the base assembly and the side plate. 
     
     
         15 . A mechanical stretching device in a movable seat, comprising:
 a base assembly fixedly supported on a ground;   a side plate movably supported above the base assembly, wherein the side plate is configured to connect to the seating portion of the movable seat; and   a backrest assembly pivotally connected to a rear portion of the side plate, wherein the backrest assembly comprises a backrest mounting member and a backrest connecting rod assembly, wherein the backrest connecting rod assembly comprises a first backrest connecting rod and a second backrest connecting rod, an upper end of the first backrest connecting rod is hinged to a front end of the backrest mounting member at a first pivot point, a front end of the second backrest connecting rod is hinged to the side plate at a second pivot point, and the middle portion of the second backrest connecting rod is hinged to the first backrest connecting rod, wherein the backrest connecting rod assembly compresses to rotate the backrest mounting member rearward about the first pivot point and the backrest connecting rod assembly expands to rotate the backrest mounting member forward about the first pivot point.   
     
     
         16 . The mechanical stretching device according to  claim 15 , further comprising:
 a central coupling element movably connected between the side plate and the backrest assembly, wherein relative movement between the central coupling element and the side plate drives the backrest connecting rod assembly to compress so that the backrest mounting member rotates rearward about the first pivot point and the backrest connecting rod assembly moves forward relative to the ground toward the front of the movable seat.   
     
     
         17 . The mechanical stretching device according to  claim 16 , comprising:
 a leg stretching device pivotally connected to a front portion of the side plate, wherein the leg stretching device comprises a first footrest element configured to attach a footrest,   wherein the mechanical stretching device transitions at least between a sitting position and a lying position,   wherein in the sitting position, the first footrest element is retracted beneath the seating portion;   wherein in the lying position, the backrest of the movable seat is reclined and the first footrest element is extended forward relative to the sitting position; and   wherein a distance between the first pivot point and the second pivot point is reduced in the lying position compared to the sitting position.   
     
     
         18 . The mechanical stretching device according to  claim 17 ,
 wherein the backrest connecting rod assembly further comprises a third backrest connecting rod, wherein a lower end of the first backrest connecting rod is hinged to the central coupling element at a third pivot point, an upper end of the third backrest connecting rod is hinged to a rear end of the backrest mounting member, and a lower end of the third backrest connecting rod is hinged to a rear end of the second backrest connecting rod, and   wherein in transition of the movable seat from the sitting position to the lying position, relative movement between the side plate and the central coupling element increases a distance between the second pivot point and the third pivot point and compresses the backrest connecting rod assembly.   
     
     
         19 . The mechanical stretching device according to  claim 18 ,
 wherein the leg stretching device further comprises a second footrest element,   wherein in the sitting position, both the first footrest element and the second footrest element are retracted beneath the seating portion;   wherein in the lying position, the backrest is reclined, and a highest point of the footrest is higher than a highest point of the backrest, wherein both the first footrest element and the second footrest element extend forward and upward, and the second footrest element is positioned in front of the first footrest element; and   wherein the first footrest element and the second footrest element are connected via a footrest connection element, wherein the footrest connection element comprises a first connecting element and a second connecting element that are hinged to each other.   
     
     
         20 . The mechanical stretching device according to  claim 19 ,
 wherein the mechanical stretching device further comprises a front swing rod, a rear swing rod, a seat coupling element, and a side plate coupling element, wherein lower ends of the front swing rod and the rear swing rod are pivotally connected to the base assembly, and upper ends of the front swing rod and the rear swing rod are connected to the side plate via the central coupling element, the seat coupling element, and the side plate coupling element,   wherein movement of the side plate relative to the base assembly drives movement of the backrest assembly and the leg stretching device relative to the side plate, and enables the movable seat to transit between the sitting position and the lying position,   wherein in the lying position, a highest point of the first footrest element is higher than a highest point of the backrest mounting member, and   wherein the mechanical stretching device further comprises: an electric driving device coupled between the base assembly and the side plate.