Screw assembly and washing machine using the same

Abstract

A screw assembly and a washing machine using the same are disclosed. The screw assembly includes a head, to be seated on an upper surface of the rotated member, a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member, and a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool. The screw assembly may include an inner tub having a bottom surface, wherein the pulsator is to be gripped to the bottom surface of the inner tub.

1 . A screw assembly for fixing a rotated member to a rotating member for driving the rotated member, the screw assembly comprising: 
 a head, to be seated on an upper surface of the rotated member;    a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member; and    a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool.    
   
   
       2 . The screw assembly as claimed in  claim 1 , wherein the outer perimeter of the pillar has a polygonal shape.  
   
   
       3 . The screw assembly as claimed in  claim 2 , wherein the polygonal shape of the pillar is a hexagon.  
   
   
       4 . The screw assembly as claimed in  claim 1 , wherein the groove is formed in a top surface of the pillar.  
   
   
       5 . The screw assembly as claimed in  claim 4 , wherein the groove has at least one slot for receiving the second tool.  
   
   
       6 . The screw assembly as claimed in  claim 1 , wherein the rotated member is a pulsator of a washing machine and the rotating member is a drive shaft coupled to a motor for driving the pulsator.  
   
   
       7 . The screw assembly as claimed in  claim 6 , further comprising an inner tub having a bottom surface, wherein the pulsator is to be gripped to the bottom surface of the inner tub.  
   
   
       8 . A screw assembly for fixing a rotated member to a rotating member for driving the rotated member, the screw assembly comprising: 
 a screw, including: 
 a head, to be seated on an upper surface of the rotated member;  
 a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member; and  
 a plurality of protrusions formed on a lower surface of the head; and  
   a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction.    
   
   
       9 . The screw assembly as claimed in  claim 8 , wherein each protrusion comprises two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the leading surface of each protrusion having an inclined surface.  
   
   
       10 . The screw assembly as claimed in  claim 8 , wherein each protrusion comprises two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the trailing surface of each protrusion being substantially perpendicular to the lower surface of the head.  
   
   
       11 . The screw assembly as claimed in  claim 8 , wherein, when the screw is tightened, the at least one fin is temporarily deformed to allow the protrusions to pass over the washer.  
   
   
       12 . The screw assembly as claimed in  claim 8 , wherein the at least one fin has a first surface for preventing the screw from being released when the rotated member is rotated in the releasing direction of the screw.  
   
   
       13 . The screw assembly as claimed in  claim 8 , wherein the at least one fin has a second surface, bent with respect to the first surface, to be deflected by the protrusions when the screw is rotated in a tightening direction.  
   
   
       14 . The screw assembly as claimed in  claim 8 , wherein the washer is formed to receive the lower surface of the head.  
   
   
       15 . The screw assembly as claimed in  claim 8 , wherein the lower surface of the head is conic in shape.  
   
   
       16 . The screw assembly as claimed in  claim 15 , further comprising a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool.  
   
   
       17 . The screw assembly as claimed in  claim 16 , wherein the outer perimeter of the pillar has a polygonal shape.  
   
   
       18 . The screw assembly as claimed in  claim 17 , wherein the polygonal shape of the pillar is a hexagon.  
   
   
       19 . The screw assembly as claimed in  claim 18 , wherein the pillar has a groove for receiving a second tool.  
   
   
       20 . The screw assembly as claimed in  claim 8 , wherein the groove has at least one slot for receiving the second tool.  
   
   
       21 . A washing machine, comprising: 
 a pulsator;    a drive shaft for driving the pulsator;    a screw, including: 
 a head seated on an upper surface of the pulsator;  
 a body, extending downwardly from the head, screwed into the drive shaft and thereby gripping the pulsator between the head and the drive shaft; and  
 a plurality of protrusions formed on a lower surface of the head;  
   a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction; and    a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool.    
   
   
       22 . The washing machine as claimed in  claim 21 , further comprising an inner tub having a bottom surface, wherein the pulsator is gripped to the bottom surface of the inner tub.  
   
   
       23 . A washing machine, comprising: 
 a cabinet;    an outer tub disposed inside the cabinet;    an inner tub rotatably installed inside the outer tub;    a pulsator fixed with respect to the inner tub;    drive means for rotating the pulsator and inner tub via a shaft coupled to the pulsator; and    a screw for coupling the pulsator to the shaft, the screw including: 
 a head seated on an upper surface of the pulsator;  
 a body, extending downwardly from the head, screwed into the drive shaft and thereby clamping the pulsator between the head and the drive shaft; and  
 a plurality of protrusions formed on a lower surface of the head.  
   
   
   
       24 . The washing machine as claimed in  claim 23 , wherein the screw assembly further comprises a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction.  
   
   
       25 . The washing machine as claimed in  claim 24 , wherein each protrusion comprises two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the leading surface of each protrusion having an inclined surface and the trailing surface of each protrusion being substantially perpendicular to the lower surface of the head.