Motor-driven footrest device of seat

Abstract

A motor-driven footrest device of a seat, comprises a footrest; an expanding mechanism having one end equipped with the footrest, the expanding mechanism being movable to assume a shrunk condition wherein the footrest is received in an opening formed in a seat cushion of the seat and an expanded condition wherein the footrest is projected from the opening to permit the feet of a seat occupant to be put thereon; an electric drive unit connected to the other end of the expanding mechanism to move the same to assume the shrunk condition and the expanded condition by the force of an electric power; and a mounting structure secured to a base structure of the seat, the mounting structure carrying both of the expanding mechanism and the electric drive unit.

What is claimed is:  
     
         1 . A motor-driven footrest device of a seat, comprising: 
 a footrest ( 10 );    an expanding mechanism having one end equipped with said footrest, said expanding mechanism being movable to assume a shrunk condition (FIG. 7) wherein said footrest is received in an opening formed in a seat cushion of said seat and an expanded condition (FIG. 8) wherein said footrest is projected from said opening to permit the feet of a seat occupant to be put thereon;    an electric drive unit ( 22 ) connected to the other end of said expanding mechanism to move the same to assume said shrunk condition and said expanded condition by the force of an electric power; and    a mounting structure ( 6   o ) secured to a base structure of said seat, said mounting structure carrying both of said expanding mechanism and said electric drive unit.    
     
     
         2 . A motor-driven footrest device as claimed in    claim 1   , in which said expanding mechanism comprises: 
 a first link mechanism ( 9 ) including a supporting frame ( 12 ) which is pivotally supported by said mounting structure ( 6   o ) and has mutually opposed guide grooves ( 12   b ), said guide grooves slidably receiving therein side edges of said footrest ( 10 ); and    a second link mechanism ( 28 ) including a link member ( 29 ) which has one end pivotally connected to said footrest and the other end actuated by said electric drive unit ( 22 ); and    a power transmission mechanism ( 24 ,  26 ,  27 ) arranged between said electric drive unit and the other end of said second link mechanism to transmit a power of said electric drive unit to said second link mechanism;    whereby when said electric drive unit is energized, said link member ( 29 ) of the second link mechanism ( 28 ) is moved to pivot said footrest ( 10 ) together with said supporting frame ( 12 ) while inducing a sliding movement of said footrest in said guide grooves ( 12   b ) of said supporting frame.    
     
     
         3 . A motor-driven footrest device as claimed in    claim 2   , in which said first link mechanism further comprises: 
 two holding arms ( 8 ) secured to said mounting structure;    two supporting arms ( 13 ) secured to said supporting frame ( 12 ); and    two pivot units each being arranged between one of said holding arms ( 8 ) and the corresponding of said supporting arms ( 13 ) thereby to induce a pivotal movement of said supporting frame relative to holding arms ( 8 ).    
     
     
         4 . A motor-driven footrest device as claimed in    claim 3   , in which each of said pivot units comprises: 
 front and rear links ( 9 A,  9 B), each having one end pivotally connected to the corresponding holding arm ( 8 ) and the other end pivotally connected to the corresponding supporting arm ( 13 ),    wherein the distance between the pivoted portions of said front and rear links to said holding arm ( 8 ) is greater than the distance between the pivoted portions of said front and rear links to said supporting arm ( 13 ).    
     
     
         5 . A motor-driven footrest device as claimed in    claim 2   , in which said second link mechanism ( 28 ) further comprises: 
 a supporting bracket ( 31 ) secured to said supporting frame ( 12 ), said supporting bracket ( 31 ) being pivotally connected to said link member ( 29 ).    
     
     
         6 . A motor-driven footrest device as claimed in    claim 5   , in which said power transmission mechanism comprises: 
 a speed reduction gear ( 24 ) driven by said electric drive unit  23 );    a threaded drive shaft ( 26 ) driven by said speed reduction gear ( 24 ); and    a nut member ( 27 ) operatively engaged with said threaded drive shaft, said nut member being pivotally connected to the other end of said link member ( 29 ).    
     
     
         7 . A motor-driven footrest device as claimed in    claim 6   , in which said second link mechanism ( 28 ) further comprises an elongate case ( 21 ) which is secured to said mounting structure ( 6   o ) to cover said threaded drive shaft ( 26 ).  
     
     
         8 . A motor-driven footrest device as claimed in    claim 1   , in which said footrest comprises: 
 a rectangular sliding frame ( 14 );    a metal block ( 15   a ) secured to said sliding frame;    a spring wire structure ( 15 ) secured to said metal block;    a base frame ( 16 ) detachably coupled with said sliding frame having said spring wire structure interposed therebetween;    a pad member ( 17 ) covering said base frame; and    a trim member ( 18 ) covering said pad member,    wherein said spring wire structure ( 15 ) is arranged to cause said base frame to have a resiliency relative to said sliding frame.    
     
     
         9 . A motor-driven footrest device as claimed in    claim 8   , in which said spring wire structure ( 15 ) comprises a pair of rectangular spring wire structures ( 15   b ,  15   c ) which are secured to the metal block ( 15   a ) and extend radially outward from the metal block.  
     
     
         10 . A motor-driven footrest device as claimed in    claim 9   , in which said base frame ( 16 ) is equipped with hooks which catch lower sections of said rectangular wire structures.  
     
     
         11 . A motor-driven footrest device as claimed in    claim 10   , further comprising clips ( 16   h ,  16   i ) held by openings formed in said base frame ( 16 ), said clips catching upper sections of said rectangular wire structures.  
     
     
         12 . A motor-driven footrest device as claimed in    claim 11   , in which said footrest further comprises sliders ( 19 A,  19 B) which are connected to side edges of said rectangular sliding frame ( 14 ) to smooth a sliding movement of said sliding frame relative to guide grooves ( 12   b ) defined by a supporting frame ( 12 ), said supporting frame being an element of said expanding mechanism.  
     
     
         13 . A motor-driven footrest device as claimed in    claim 12   , in which each of the sliders is constructed of a plastic and comprises: 
 a longer side wall ( 19   b );    a shorter front wall ( 19   c ) integrally connected to said longer side wall to form a unit having a generally L-shaped cross section; and    a plurality of engaging pawls ( 19   a ) integrally formed on said unit, said engaging pawls being detachably engaged with said rectangular sliding frame ( 14 ).    
     
     
         14 . A motor-driven footrest device as claimed in    claim 2   , in which said link member ( 29 ) is formed with an expanded portion to serve as a shock absorber.  
     
     
         15 . A motor-driven footrest device as claimed in    claim 14   , in which said link member comprises: 
 two parallel side walls having outwardly swelled portions ( 29   e ,  29   f ) at one end portions thereof; and    two connecting walls each extending between said two parallel side walls.    
     
     
         16 . A motor-driven footrest device as claimed in    claim 15   , in which each of said swelled portions of said parallel side walls is shaped to have a trapezoidal cross section.  
     
     
         17 . A motor-driven footrest device as claimed in    claim 15   , in which each of said swelled portions of said parallel side walls of said link member is shaped to have a semi-cylindrical cross section.  
     
     
         18 . A motor-driven footrest device as claimed in    claim 15   , in which the two parallel side walls of said link member are formed with respective cuts ( 29   g ) with which the mechanical strength of the parallel side walls around said cuts is lowered.  
     
     
         19 . A motor-driven footrest device for use with a sliding seat, comprising: 
 a footrest ( 10 );    an expanding mechanism having one end equipped with said footrest, said expanding mechanism being movable to assume a shrunk condition (FIG. 7) where said footrest is received in an opening formed in a seat cushion of said seat and an expanded condition (FIG. 8) wherein said footrest is projected from said opening to permit a seat occupant's feet to put thereon;    an electric drive unit ( 22 ) connected to the other end of said expanding mechanism to move the same to assume said shrunk condition and said expanded condition by the force of an electric power;    a seat slide mechanism ( 6 ) for sliding the seat, said seat slide mechanism including two fixed rails ( 6   a ,  6   b ) secured to a fixed structure, and two slide rails slidably engaged with said fixed rails and mounting thereon the seat; and    a mounting structure ( 6   o ) secured to said two slide rails to move therewith, said mounting structure carrying both of said expanding mechanism and said electric drive unit.    
     
     
         20 . A motor-driven footrest device as claimed in    claim 19   , in which said expanding mechanism comprises: 
 a first link mechanism ( 9 ) including a supporting frame ( 12 ) which is pivotally supported by said mounting structure ( 6   o ) and having mutually opposed guide grooves ( 12   b ), said guide grooves slidably receiving therein side edges of said footrest; and    a second link mechanism ( 28 ) including a link member ( 29 ) which has one end pivotally connected to said footrest and the other end actuated by said electric drive unit ( 22 ), said link member having an breakable portion to serve as a shock absorbing member; and    a power transmission mechanism ( 24 ,  26 ,  27 ) arranged between said electric drive unit and the other end of said second link mechanism to transmit a power of said electric drive unit to said second link mechanism,    whereby when said electric drive unit is energized, said link member ( 29 ) of the second link mechanism ( 28 ) is forced to move to pivot said footrest together with said supporting frame ( 12 ) while inducing a sliding movement of the side edges of said footrest in said guide grooves ( 12   b ) of said supporting frame.    
     
     
         21 . A motor-driven footrest device as claimed in    claim 19   , in which said seat slide mechanism ( 6 ) further comprises an electric motor ( 6   e ) for moving the slide rails relative to the fixed rails by the force of an electric power.