Elastic Force Enhancing Structure of Self-Opening/Closing Umbrella

Abstract

An elastic force enhancing structure is provided for a center post of a self-opening/closing umbrella. The center post includes inner, intermediate, and outer tubes telescopically connected. A primary spring is received in the center post. The outer tube receives therein an elastic force enhancing spring and a joint sleeve that has an upper end forming an inner flange extends inwardly and a lower end forming an outer flange extends outwardly. The joint sleeve is fit over an upper end of the primary spring to have the inner flange and the upper end of the primary spring in abutting engagement. The elastic force enhancing spring has a lower end fit over the joint sleeve so that the lower end is in abutting engagement with the outer flange. As such, the elastic force enhancing spring is coupled, via the joint sleeve, to the primary spring to provide an extended configuration.

I claim: 
     
         1 . An elastic force enhancing structure of a self-opening/closing umbrella, which is mounted in an umbrella that has a center post including a single pull cord and a primary spring, the umbrella center post comprising an inner tube, an intermediate tube, and an outer tube sequentially and telescopically fit to each other, the inner tube having a lower end to which a bottom plug is fit, the outer tube having an upper end to which a top plug is fit, a cord sleeve having an upper end fixed to the top plug and a lower end located in the intermediate tube, the improvements comprising an elastic force enhancing spring additionally provided inside the outer tube, the elastic force enhancing spring being coupled via a joint sleeve to an upper end of the primary spring to provide an extended configuration. 
     
     
         2 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 1 , wherein the joint sleeve has an upper end from which an inner flange extends inwardly, the joint sleeve being fit over the upper end of the primary spring, the inner flange being set in abutting engagement with the upper end of the primary spring, the joint sleeve having a lower end from which an outer flange extends outwardly, the elastic force enhancing spring being fit over the joint sleeve in such a way that a lower end thereof is set in abutting engagement with the outer flange, the elastic force enhancing spring having an outside diameter that is set in gap-intervened fitting with an inner wall of the outer tube and an inside diameter that is set in gap-intervened fitting with an outer wall of the joint sleeve. 
     
     
         3 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 1 , wherein an outer tube advance ejection spring is arranged between the outer flange of the joint sleeve and an upper end of the intermediate tube, the outer tube advance ejection spring having a spring force smaller than spring force of the elastic force enhancing spring. 
     
     
         4 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 1 , wherein the joint sleeve has an upper end from which an outer flange extends outwardly, the primary spring having an upper end that is fit to the joint sleeve in such a way that the outer flange and the upper end of the primary spring form abutting engagement, the joint sleeve having a lower end from which an inner flange extends inwardly, the joint sleeve being fit over a lower end of the elastic force enhancing spring in such a way that the inner flange and the lower end of the elastic force enhancing spring form abutting engagement, the elastic force enhancing spring having an outside diameter that is set in gap-intervened fitting with an inner wall of the joint sleeve. 
     
     
         5 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 1 , wherein an outer tube advance ejection spring is arranged between an outer flange of the joint sleeve and an upper end of the intermediate tube, the outer tube advance ejection spring having a spring force that is smaller than spring force of the elastic force enhancing spring. 
     
     
         6 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 1 , wherein the joint sleeve is oppositely arranged in such a way that a lower end thereof comprising an inner flange extending inwardly therefrom and an upper end thereof comprising an outer flange extending outwardly therefrom, the intermediate tube having an upper end to which an intermediate plug is mounted to retain an upper end of the primary spring, a secondary spring being arranged between the intermediate plug and the joint sleeve, the secondary spring having an inside diameter that is fit to an inner wall of the outer tube in such a manner that a gap is formed therebetween, the secondary spring having an upper end fit over the joint sleeve and set in abutting engagement with the outer flange, the outer flange being fit to an inner wall of the outer tube in such a manner that a gap is formed therebetween, the elastic force enhancing spring having a lower end fit in the joint sleeve in such a way that the lower end is set in abutting engagement with the inner flange and the upper end is in abutting engagement with the top plug. 
     
     
         7 . An elastic force enhancing structure of a self-opening/closing umbrella, which is mounted in an umbrella that has a center post including two pull cords and a primary spring, the umbrella center post comprising an inner tube, an intermediate tube, and an outer tube sequentially and telescopically fit to each other, the inner tube having a lower end to which a bottom plug is fit, the outer tube having an upper end to which a top plug is fit, wherein besides the primary spring, two pull cords and a cord sleeve are arranged inside the umbrella center post, the intermediate tube having an upper end to which an intermediate plug having a center forming a through hole is mounted, the cord sleeve having an upper end fixed to the intermediate plug, the improvements comprising an elastic force enhancing spring additionally provided inside the intermediate tube, the elastic force enhancing spring being coupled via a joint sleeve to an upper end of the primary spring to provide an extended configuration. 
     
     
         8 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 7 , wherein the joint sleeve is fit outside the cord sleeve and has a lower end from which an inner flange extends inwardly and an upper end from which an outer flange extends outwardly, the primary spring having an upper end fit to the joint sleeve so that the upper end of the primary spring is supported on the outer flange, the elastic force enhancing spring being fit over the cord sleeve in such a way that the elastic force enhancing spring has an upper end supported on a lower end of the intermediate plug and the elastic force enhancing spring has a lower end supported on the inner flange. 
     
     
         9 . The elastic force enhancing structure of the self-opening/closing umbrella according to  claim 7 , wherein the intermediate plug comprises a pulley mounted at one side of the upper end thereof, one of the pull cords having an upper end extending through the top plug to couple to a runner and a lower end extending through the cord sleeve to couple to an upper end of a retention terminal, the other one of the pull cords having a lower end that is coupled to the upper end of the retention terminal and an upper end extending through the cord sleeve and the intermediate plug and then wrapped around the pulley to couple to a lower end of the outer tube.