Sofa seat stretching device

A sofa seat stretching device, comprising a base, two stretching assemblies and a driving assembly, wherein the two stretching assemblies and the driving assembly are disposed on the base,

• wherein two stretching assemblies comprise two backrest units, two seat frame units and two leg stretching units, wherein the two backrest units, the two seat frame units and the two leg stretching units are symmetrically disposed at both ends of the base in a width direction of the base, two ends of each of the two seat frame units are hinged to one end of one backrest unit of the two backrest units, and one end of one leg stretching unit of the two leg stretching units respectively;
• the driving assembly is configured to drive the two stretching assemblies to stretch or retract synchronously in a length direction of the two stretching assemblies so that the two stretching assemblies switch between a sitting position state, a TV position state, and a lying position state,
• wherein each of the two leg stretching units comprises a first leg rest plate connector and a second leg rest plate connector, a middle of the first leg rest plate connector and a middle of the second leg rest plate connector are hinged to a third hinge point;
• each of the two seat frame units-comprises a seat frame support, a first support, a second support and a third support, wherein the seat frame support is hinged to one end of the second leg rest plate connector at a first hinge point, the first support, the second support and the third support are each rotatable relative to the seat frame support, one end of the third support is hinged to the seat frame support at a fifth hinge point;
• the other end of the third support is hinged to the first leg rest plate connector, one end of the second support is hinged to one end of the first support, the other end of the second support is hinged to the second leg rest plate connector at a fourth hinge point, the fourth hinge point is located between the first hinge point and the third hinge point, and the first hinge point is located in front of the fifth hinge point;
• each of the two seat frame units-further comprises a first connector, a second connector, a third connector, a fourth connector, a fifth connector, and a sixth connector;
• one end of the first connector is hinged to the seat frame support, a middle of the first connector is hinged to one end of the third connector, the other end of the first connector is hinged to one end of the second connector, and the other end of the second connector is hinged to a front end of the base;
• the other end of the third connector is hinged to the one of the two backrest units;
• one end of the fourth connector is hinged to a middle of the third support, and the other end of the fourth connector is hinged to one end of the sixth connector;
• a middle of the sixth connector is hinged to the seat frame support, the other end of the sixth connector is hinged to one end of the fifth connector, and the other end of the fifth connector is hinged to the middle of the second connector;
• the first connector is provided with a first stopper member for stopping a movement of the third support, the seat frame support is provided with a second stopper member for stopping a retracting of each of the two stretching assemblies, and a third stopper member for stopping a stretching of each of the two stretching assemblies, and the second stopper member and the third stopper member are located at two sides of the first connector;
• when the two stretching assemblies are in a lying position state, the third stopper member abuts against the first connector;
• when the two stretching assemblies are in a sitting position state, the second stopper member abuts against the first connector, and the first stopper member is clamped between the seat frame support and the third support;
• and
• the second leg rest plate connector is provided with a fourth stopper member for stopping an upper end surface of the first leg rest plate connector.