Overrunning clutch

Abstract

An overrunning clutch comprising a ratchet wheel ( 1 ) and a plurality of pawls ( 2 ) is disclosed. Each of the pawls ( 2 ) is rotationally supported on a disk member ( 5 ) by a shaft ( 3 ). The clutch is characterized by a permanent magnet ( 4 ) being fixed on the disk member ( 5 ) between the axes of the disk member ( 5 ) and the shaft ( 3 ) and facing the tail end of each pawl ( 2 ). Because each of the pawls are not driven by a spring in the clutch, the clutch could not be malfunction due to the fatigue failure of the spring in the case of frequent heavy load.

1 . A ratchet overrunning clutch comprising a ratchet wheel ( 1 ) and a plurality of pawls ( 2 ), each of the pawls ( 2 ) is rotationally supported on a disk member ( 5 ) by a shaft ( 3 ), wherein a permanent magnet ( 4 ) being fixed on the disk member ( 5 ) between the axes of the disk member ( 5 ) and the shaft ( 3 ) of the pawl ( 2 ) and opposing to the tail end of pawl ( 2 ).  
     
     
         2 . The clutch according to  claim 1 , wherein the pawl ( 2 ) includes a ratchet end ( 6 ) which engages with the teeth of said ratchet wheel and a tail end ( 7 ) away from the ratchet end ( 6 ), a through hole ( 8 ) for said shaft ( 3 ) is provided between the ratchet end ( 6 ) and the tail end ( 7 ).  
     
     
         3 . The clutch according to  claim 2 , wherein the distance from the tip of the ratchet end ( 6 ) to the axis of the through hole ( 8 ) is larger than that from the tip of the tail end ( 7 ) to the axis of the through hole ( 8 ).  
     
     
         4 . The clutch according to  claim 3 , wherein the ratio of the distance from the tip of the tail end ( 7 ) to the center of the through hole ( 8 ) to the distance from the tip of the ratchet end ( 6 ) to the center of the through hole ( 8 ) is 1:1.1.  
     
     
         5 . The clutch according to  claim 1 , wherein the clutch further includes a mounting sleeve ( 10 ) embedded in said disk member ( 5 ), the permanent magnet ( 4 ) is provided in said mounting sleeve ( 10 ).  
     
     
         6 . The clutch according to  claim 5 , wherein the mounting sleeve ( 10 ) is made of non-magnetic material.  
     
     
         7 . The clutch according to  claim 5  or  6 , wherein the mounting sleeve ( 10 ) is made of stainless steel.  
     
     
         8 . The clutch according to  claim 1 , wherein the permanent magnet ( 4 ) is made of Neodymium-Fe-Boron.  
     
     
         9 . The clutch according to  claim 1  or  8 , wherein the shape of the permanent magnet ( 4 ) is a cylinder and its diameter is 16 mm and its height is 10 mm.  
     
     
         10 . The clutch according to claim.  1 , wherein the distance between the tail end ( 7 ) of said pawl ( 2 ) and the permanent magnet ( 4 ) is 1 mm when the ratchet end ( 6 ) of said pawl ( 2 ) engages with the teeth ( 9 ); the maximum distance between the tail end ( 7 ) of said pawl ( 2 ) and the permanent magnet ( 4 ) is 5 mm when the pawl ( 2 ) disengages with the teeth ( 9 ).