Auto-opening umbrella frame

Abstract

An enhanced frame of an auto-opening umbrella comprises hollow cylindrical intermediate pivotal joints with spreaders passed through and each including two spaced bottom lugs, a shaft integrally formed with the lugs, and a recess between the lugs. A plurality of links has hooked ends pivotably coupled to a lower ring and the shaft. The outer hooked end of each link is sufficiently smaller than the recess so that ribs are spaced apart from the spreaders by a much smaller distance when the umbrella is folded. This can achieve a smooth folding operation and a more compact umbrella after folded.

What is claimed is:  
     
         1 . A frame of an auto-opening umbrella comprising: 
 a shank including a lower ring slidable on the shank, a intermediate ring slidable on the shank, a stationary upper hub fixed on a top of the shank, and elastic means biased between the intermediate and the lower rings;    a rib assembly including a plurality of ribs;    a spreader assembly including a plurality of spreaders being pivotably coupled to both the ribs and the intermediate ring; and    a plurality of links each having an inner hooked end and an outer hooked end wherein the inner hooked ends are pivotably coupled to the lower ring;    wherein a plurality of substantially hollow cylindrical intermediate pivotal joints each comprises two connected parallel tubes having central through hole in communication with each other wherein each of the spreaders is inserted therethrough and fastened therein, two spaced bottom lugs vertically extending from the bottom of the intermediate pivotal joints, a shaft integrally formed with the lugs and across the lugs, and the outer hooked end of each link is pivotably coupled to the shaft.    
     
     
         2 . The frame of  claim 1 , wherein each of the intermediate pivotal joints has a recess between the lugs and above the shaft, and the recess having a length longer than that of a bottom portion of the lugs.  
     
     
         3 . The frame of  claim 1 , wherein the link is made of stainless steel.  
     
     
         4 . The frame of  claim 1 , wherein the outer hooked end of each link is disposed around more than half of a circumference of the shaft.  
     
     
         5 . The frame of  claim 4 , wherein the outer hooked end of each link is smaller than the recess so that the ribs are spaced apart from the spreaders by a substantially little distance when the umbrella is folded.  
     
     
         6 . The frame of  claim 1 , wherein the rib assembly has a plurality of single-rod ribs.  
     
     
         7 . The frame of  claim 1 , wherein the spreader assembly has a plurality of two parallel rod spreaders.