Umbrella frame

Abstract

An umbrella frame has a main shaft and multiple branches pivotally attached around the main shaft. The main shaft has an immovable upper base and a movable lower base each having multiple retaining slots. Each branch is divided into a front section, a middle section and a rear section and has a supporting rib and a pulling rib both pivotally attached under the front section. The front sections and the supporting ribs have pin heads to respectively engage the retaining slots on the upper and lower bases so that the branches are pivotally attached to the main shaft. Moreover, the supporting rib, the pulling ribs, the front section and middle section perform a quaternary-linkage to make operation conveniently and stably. Additionally, the umbrella frame is made of high-stiffness plastic so that the umbrella frame does not rust and has excellent anti-deforming efficiency.

1 . An umbrella frame comprising: 
 a main shaft  1  with a top having a retractable sheet  11  attached near the top;    an upper base  20  immovably mounted on the top of the main shaft  1  and having multiple retaining slots  201  longitudinally defined around the upper base  20 ;    an upper locking ring  21  with a cap  22  detachably mounted on the upper base  20 ;    a lower base  30  slidably mounted on the main shaft  1  and having multiple retaining slots  301  longitudinally defined around the lower base  30 ;    a lower locking ring  31  detachably mounted on the lower base  30 ; and    multiple branches radially attached to the upper base  20  and the lower base  30  around the main shaft  1 ;    wherein each branch is divided into a front section  50 , a middle section  80  and a rear section  10  pivotally connected in sequence and further comprising a supporting rib  60  and a pulling rib  70 ;    the front section  50  has two pin heads  501 ,  504 , wherein one of the two pin heads  501  of the front section  50  engages a corresponding one of the multiple retaining slots  201  on the upper base  20 ;    the supporting rib  60  pivotally attaches between the lower base  30  and the front section  50  and has two pin heads  601 ,  603 , wherein one of the two pin heads  601  of the supporting rib  60  engages a corresponding one of the multiple retaining slot  301  on the lower base  30 ;    the pulling rib  70  pivotally attaches between the supporting rib  60  and the middle section  80 ;    the middle section  80  has a resilient strip extending along the middle section  80  and pivotally connected between the front section  50  and the rear section  10 .    
   
   
       2 . The umbrella frame as claimed in  claim 1 , wherein the umbrella frame further has an actuating sleeve  40 A attached to the lower base  30 ; 
 the actuating sleeve  40 A sleeves on the lower base  30  below the multiple retaining slots  301  and has a resilient button  40 A 1  formed on the actuating sleeve  40 A;    the lower base  30  further has a cutout  303  defined to align to the resilient button  40 A 1  and operationally align to the retractable sheet  11  when the umbrella frame is fully extended.    
   
   
       3 . The umbrella frame as claimed in  claim 1 , wherein the front section  50  has a pin hole  502  defined at a middle of the front section  50  to engage the other one of the two pin heads  603  of the supporting rib  60 ; 
 the supporting rib  60  has a pin hole  602  defined near the pin head  603  near the front section  50 ;    the pulling rib  70  has two pin heads  701 ,  702 , wherein one of the two pin heads  701  is pivotally engaged the pin hole  602  of the supporting rib  60 ;    the middle section  80  has a pin head  804  connected to the rear section  10  and an adjacent end having    a first pivot bracket  801  at distal to engage the other one of the two pin heads  702  on the pulling rib  70 ; and    a second pivot bracket  802  near the first pivot bracket  801  to engage the other one of the two pin heads  504  on the front section  50 .    
   
   
       4 . The umbrella frame as claimed in  claim 1 , wherein the umbrella frame is made of high-stiffness plastic.  
   
   
       5 . The umbrella frame as claimed in  claim 1 , wherein the upper locking ring  21  has an inner edge and multiple notches  211  defined in intervals on the inner edge; 
 the upper base  20  has a top and multiple dividing flanges  202  formed around the upper base  20  individually over the multiple retaining slots  201  to snugly combine with the multiple notches  211  when the upper locking ring  21  mounted on the upper base  20 .    
   
   
       6 . The umbrella frame as claimed in  claim 5 , wherein upper base  20  further has a threaded hole  202  defined in the top; 
 the cap  22  mounted on the upper locking ring  21  and has a threaded rod  221  to engage the threaded hole  202  to secure the upper locking ring  21  on the upper base  20 .    
   
   
       7 . The umbrella frame as claimed in  claim 1 , wherein the lower locking ring  31  has an inner edge and multiple notches  311  defined in intervals on the inner edge; 
 the lower base  30  has a bottom and multiple dividing flanges  302  formed around the lower base  30  below the retaining slot  201  to snugly combine with the multiple notches  311  when the lower locking ring  31  mounted on the lower base  30 .    
   
   
       8 . The umbrella frame as claimed in  claim 2 , wherein the lower locking ring  31  has an inner edge and multiple notches  311  defined in intervals on the inner edge; 
 the lower base  30  has a bottom and multiple dividing flanges  302  formed around the lower base  30  below the retaining slot  201  to snugly combine with the multiple notches  311  when the lower locking ring  31  is clamped between the lower base  30  and the actuating sleeve  40 A.    
   
   
       9 . The umbrella frame as claimed in  claim 1 , wherein the umbrella frame further has a positioning sleeve  40 A 1  attached to the lower base  30 .