Umbrella having worm-gear based driving system

Abstract

An umbrella includes a center post having upper and lower sections pivotally connected together. A crown is mounted to the upper section. A number of ribs are pivoted to and radially extend from the crown. A runner is movably mounted to the center post. A stretcher is arranged between and pivoted to the runner and each rib. A canopy is attached to and supported by the ribs. A worm-gear based driving system converts the rotation of the worm caused by manual operation into linear movement of a nut engaging a threaded shaft of the gear. A link is arranged between and pivoted to the nut and the upper section whereby the linear movement of the nut drives the link to swivel the upper section relative to the lower section about the pivotal connection between the upper and lower sections. The worm-gear based driving system may also be employed to move the runner with respect to the center post for opening/closing the umbrella. The runner has a projection extending through an axially-extending slit defined in the center post and having an inner-threaded member engaging a threaded shaft of the gear whereby the rotation of the worm is converted into linear movement of the inner-threaded member and the runner with respect to the center post for opening/closing the umbrella.

What is claimed is:  
     
         1 . An umbrella comprising: 
 an umbrella frame comprising: 
 a center post comprising an upper section and a lower section pivotally connected to the upper section,  
 a crown mounted to the upper section of the center post,  
 a number of ribs pivotally attached to the crown and radially extending from the crown,  
 a runner movable along the center post, and  
 a stretcher extending between and pivotally connected to the runner and each rib; and  
   a driving system comprising: 
 a worm rotatably supported in the lower section and rotatable by a manual control device,  
 a shaft extending substantially in parallel to the lower section of the center post and comprising a gear mounted thereto, the gear mating the worm, the shaft having an external threading,  
 a nut threadingly engaging the external threading of the shaft whereby the rotation of the worm is converted into linear movement of the nut along the shaft, and  
 a link having an end pivoted to the nut and an opposite end pivoted to an extension of the upper section and offset from the pivotal connection between the upper and lower section;  
 whereby rotating the worm by the manual control device drives the link to swivel the upper section relative to the lower section about the pivotal connection between the upper and lower sections.  
   
     
     
         2 . The umbrella as claimed in  claim 1 , wherein the manual control device comprises a rotation knob located outside the lower section of the center post and mounted to the worm.  
     
     
         3 . An umbrella comprising: 
 an umbrella frame comprising: 
 a center post defining a slit extending substantially parallel thereto,  
 a crown mounted to the center post,  
 a number of ribs pivotally attached to the crown and radially extending from the crown,  
 a runner movable along the center post, the runner comprising a projection extending through the slit into the center post,  
 a stretcher extending between and pivotally connected to the runner and each rib; and  
   a driving system comprising: 
 a worm rotatably supported in the center post and rotatable by a manual control device,  
 a shaft extending substantially in parallel to the center post and comprising a gear mounted thereto, the gear mating the worm, the shaft having an external threading, and  
 a nut mounted to the projection of the runner and threadingly engaging the external threading of the shaft whereby the rotation of the worm is converted into linear movement of the nut and the runner along the shaft toward/away from the crown for opening/closing the umbrella.  
   
     
     
         4 . The umbrella as claimed in  claim 3 , wherein the manual control device comprises a crank handle located outside the center post and mounted to the worm.