Mechanical stretching device for movable seat unit and seat unit

Abstract

The present disclosure relates to a mechanical stretching device for a movable seat unit, including: a seat assembly, including a base assembly, a lateral plate, and a central driven member; a backrest assembly, pivotally connected to a rear part of the lateral plate; a leg stretching device, pivotally connected to a front part of the lateral plate, including a first footrest member; the mechanical stretching device allows the seat unit to be switched between a sitting position and a lying position; the first footrest member is folded below a seat when in the sitting position; and the backrest is relined backward, a highest point of the footrest is higher than a highest point of the backrest, and the first footrest member is stretched forward and upward, when in the lying position. The present disclosure further relates to a movable seat unit.

1 . A mechanical stretching device for a movable seat unit, comprising:
 a seat assembly, comprising a base assembly, a lateral plate attached to a seat of the seat unit, and a central driven member coupled between the base assembly and the lateral plate;   a backrest assembly, pivotally connected to a rear part of the lateral plate, comprising a backrest connecting member configured to be attached to a backrest of the seat unit and a backrest link assembly pivotally connected to the backrest connecting member, the backrest link assembly comprising a first backrest link hinged to the central driven member and a second backrest link hinged to the lateral plate, wherein the first backrest link is hinged to the second backrest link;   a leg stretching device, pivotally connected to a front part of the lateral plate, comprising a plurality of links pivotally connected with each other and a first footrest member configured to be attached to a footrest,   wherein the mechanical stretching device allows the seat unit to be switched between a sitting position, a TV position, and/or a lying position; the first footrest member is folded below a seat when in the sitting position; the first footrest member is stretched forward when in the TV position; and the backrest is relined backward, a highest point of the footrest is higher than a highest point of the backrest, and the first footrest member is stretched forward and upward, when in the lying position.   
     
     
         2 . The mechanical stretching device according to  claim 1 , wherein the backrest is reclined at least 35° more in the lying position than in the sitting position. 
     
     
         3 . The mechanical stretching device according to  claim 1 , wherein a front end of the first footrest member is raised in the lying position, so that an acute angle with an opening facing forward in a range of 10° to 23° is formed between a footrest surface of the first footrest member and a horizontal plane. 
     
     
         4 . The mechanical stretching device according to  claim 1 , wherein the leg stretching device further comprises a second footrest member; both the first footrest member and the second footrest member are folded below the seat when in the sitting position; both the first footrest member and the second footrest member are stretched forward when in the TV position; and the backrest is relined backward, a highest point of the footrest is higher than a highest point of the backrest, the first footrest member is stretched forward and upward, when in the lying position, and the second footrest member is located in front of the first footrest member. 
     
     
         5 . The mechanical stretching device according to  claim 4 , wherein a front end of the second footrest member is raised in the lying position, so that an acute angle with an opening facing forward in a range of 10° to 23° is formed between a footrest surface of the second footrest member and a horizontal plane. 
     
     
         6 . The mechanical stretching device according to  claim 4 , wherein a front end of the second footrest member is lowered in the lying position, so that an acute angle with an opening facing backward in a range of 8° to 30° is formed between a footrest surface of the second footrest member and a horizontal plane. 
     
     
         7 . The mechanical stretching device according to  claim 4 , wherein the first footrest member is connected to the second footrest member through a footrest extension assembly, and the footrest extension assembly comprises a first extension member and a second extension member hinged to each other. 
     
     
         8 . The mechanical stretching device according to  claim 1 , wherein the backrest link assembly further comprises a third backrest link, a fourth backrest link, and a fifth backrest link; a lower end of the third backrest link is hinged to the second backrest link, an upper end of the third backrest link is hinged to a rear end of the backrest connecting member, an upper end of the fourth backrest link is hinged to a front end of the backrest connecting member at a first hinge point, a front end of the fifth backrest link is hinged to the first backrest link at a second hinge point, a rear end of the fifth backrest link is hinged to a middle of the third backrest link, and a lower end of the fourth backrest link is hinged to a middle of the fifth backrest link. 
     
     
         9 . The mechanical stretching device according to  claim 8 , wherein, when the seat unit is switched from the sitting position to the lying position, a relative movement between the lateral plate and the central driven member leads to an increase in a distance from a hinge point between the first backrest link and the central driven member to a hinge point between the second backrest link and the lateral plate, so as to achieve compression of the backrest link assembly. 
     
     
         10 . The mechanical stretching device according to  claim 8 , wherein, when the seat unit is switched from the sitting position to the lying position, both the first hinge point and the second hinge point are moved forward, and a distance between the first hinge point and the second hinge point is decreased. 
     
     
         11 . The mechanical stretching device according to  claim 1 , wherein the seat assembly further comprises a front swing rod, a rear swing rod, a seat driven member, and a lateral plate driven member; lower ends of both the front swing rod and the rear swing rod are pivotally connected to the base assembly, upper ends of both the front swing rod and the rear swing rod are connected to the lateral plate through the central driven member, the seat driven member, and the lateral plate driven member. 
     
     
         12 . The mechanical stretching device according to  claim 1 , wherein the mechanical stretching device further comprises an electric driving device coupled between the base assembly and the lateral plate, the electric driving device comprises a first electric driver and a second electric driver, the first electric driver is configured to cause the leg stretching device to stretch and retract relative to the seat assembly, and the second electric driver is configured to cause the backrest assembly to move relative to the seat assembly. 
     
     
         13 . The mechanical stretching device according to  claim 12 , wherein the leg stretching device further comprises a second footrest member; when the first electric driver causes the leg stretching device to stretch to the front of the seat assembly, the second footrest member is located in front of the first footrest member. 
     
     
         14 . The mechanical stretching device according to  claim 12 , wherein the first electric driver acts between the seat assembly and the leg stretching device, and the second electric driver acts between the base assembly and the seat assembly. 
     
     
         15 . The mechanical stretching device according to  claim 14 , wherein the base assembly comprises a base rear crossbeam, the leg stretching device comprises a first motor crossbar, the seat assembly comprises a second motor crossbar close to the leg stretching device and a third motor crossbar close to the backrest assembly; the first electric driver acts between the first motor crossbar and the second motor crossbar, and the second electric driver acts between the third motor crossbar and the base rear crossbeam. 
     
     
         16 . The mechanical stretching device according to  claim 15 , wherein the second motor crossbar is connected to the lateral plate, and the third motor crossbar is connected to the central driven member. 
     
     
         17 . The mechanical stretching device according to  claim 12 , wherein the backrest link assembly further comprises a third backrest link, a fourth backrest link, and a fifth backrest link; a lower end of the third backrest link is hinged to the second backrest link, an upper end of the third backrest link is hinged to a rear end of the backrest connecting member, an upper end of the fourth backrest link is hinged to a front end of the backrest connecting member at a first hinge point, a front end of the fifth backrest link is hinged to the first backrest link at a second hinge point, a rear end of the fifth backrest link is hinged to a middle of the third backrest link, and a lower end of the fourth backrest link is hinged to a middle of the fifth backrest link. 
     
     
         18 . The mechanical stretching device according to  claim 17 , wherein, when the backrest assembly is moved relative to the seat assembly through the second electric driver, a relative movement between the lateral plate and the central driven member leads to an increase in a distance from a hinge point between the first backrest link and the central driven member to a hinge point between the second backrest link and the lateral plate, so as to achieve compression of the backrest link assembly. 
     
     
         19 . The mechanical stretching device according to  claim 17 , wherein when the backrest assembly is moved relative to the seat assembly through the second electric driver, both the first hinge point and the second hinge point are moved forward, and a distance between the first hinge point and the second hinge point is decreased. 
     
     
         20 . The mechanical stretching device according to  claim 12 , wherein the seat assembly further comprises a front swing rod, a rear swing rod, a seat driven member, a lateral plate driven member, and a driving link; lower ends of both the front swing rod and the rear swing rod are pivotally connected to the base assembly, upper ends of both the front swing rod and the rear swing rod are connected to the lateral plate through the central driven member, the seat driven member, and the lateral plate driven member, an upper end of the driving link is hinged to a middle of the seat driven member, and a lower end of the driving link is hinged to a middle of the base assembly.