Disengageable quick-lock connection for telescopic shaft

Abstract

A telescopic shaft for rapid length adjustment consists of a tube having a plurality of alternating circumferential ridges and grooves on at least a portion of an inner surface and having an oval cross-section with a major diameter D A and a minor diameter D B ; a shaft disposed within the tube and having matching circumferential ridges and grooves, the shaft also having an oval cross-section with a major diameter D C and a minor diameter D D ; and the ridges and grooves of the tube interengaging with the grooves and ridges of the shaft when the shaft major diameter D C is substantially parallel with the tube minor diameter D B .

Having described the invention, we claim:  
     
         1 . A telescopic shaft for rapid length adjustment, comprising: 
 a tube having a plurality of substantially circumferential alternating ridges and grooves on at least a portion of its inner surface and having an oval cross-section with an inside major diameter D A  and minor diameter D B ;    an inner shaft member disposed within said tube and having matching ridges and grooves, said inner shaft member also having an oval cross-section with a major diameter D C  and a minor diameter D D ; and    the ridges and grooves of said tube interengaging with the grooves and ridges of said inner shaft when the shaft major diameter D C  is substantially parallel with the tube minor diameter D B .    
     
     
         2 . The telescopic shaft of    claim 1   , further comprising: 
 means for limiting rotation of said inner shaft member within said tube.    
     
     
         3 . The telescopic shaft of    claim 2   , wherein the means for limiting rotation of said inner shaft member within said tube comprises said inner shaft major diameter D C  being slightly greater than said tube minor diameter D B , such that said inner shaft is limited to slightly less than 180° of rotation within said tube and said ridges and grooves are fully interengaged at the limits of rotation.  
     
     
         4 . The telescopic shaft of    claim 1   , wherein the circumferential alternating ridges and grooves comprise a continuous thread.  
     
     
         5 . The telescopic shaft of    claim 1   , further comprising: 
 a centering plug having an oval cross-section and a slip fit in the tube, said plug being rotatably attached to the end of the inner shaft member for radially centering said shaft member within said tube.    
     
     
         6 . The telescopic shaft of    claim 2   , wherein the means for limiting rotation of said inner shaft member within said tube comprises at least one axial discontinuity in the ridges and grooves of the tube to act as a stop against further rotation when the inner shaft has been rotated to the locked position in the tube.  
     
     
         7 . A method for making a quick-change length-adjustable telescopic shaft, comprising the following steps: 
 providing an outer tube member having an oval cross-section with an inside major diameter D A  and minor diameter D B ;    forming a plurality of substantially circumferential alternating ridges and grooves on at least a portion of the inner surface of said outer tube member;    providing an inner shaft member having an oval cross section with a major diameter D C  and a minor diameter D D ;    forming a plurality of substantially circumferential alternating ridges and grooves on at least a portion of the outer surface of said inner shaft member.    
     
     
         8 . The method of    claim 7   , comprising the further step of: 
 rotatably attaching a centering plug to the end of the inner shaft member for radially centering said inner shaft member within said outer tube member.    
     
     
         9 . The method of    claim 7   , comprising the further step of: 
 forming at least one axial discontinuity in the ridges and grooves of the outer tube member to act as a rotation stop when the inner shaft member has been rotated to the locked position in the outer tube member.    
     
     
         10 . A method for making a quick-change length-adjustable telescopic shaft, comprising the following steps: 
 providing an outer tube member;    deforming said outer tube member to provide an oval cross-section with an inside major diameter and minor diameter;    providing a hollow inner shaft member;    deforming said inner shaft member to provide a continuous oval cross-section with an outside major diameter and minor diameter, the major diameter of said inner shaft being equal to the minor diameter of the outer tube; and    forming a plurality of matching alternating circumferential ridges and grooves on at least a portion of the inside surface of the outer tube member and the outside surface of the inner shaft member.