The present invention relates to a folding shaft for umbrellas and the sections of the shaft includes polygonal shape sections and circular shape sections which are be alternatively connected to the sections of polygonal shape.
A conventional folding shaft of an umbrella generally includes three or four sections which are retractably connected to each other in a sequence such that when the umbrella is not in use, the shaft can be folded to be a short shaft. The foldable shaft is cooperated with an opening device which includes a spring arranged to be extended through the sections of the shaft. In order to smoothly extend or fold the shaft, the inner diameter of each section has to be controlled so as to ensure smooth operation while the opening device can be installed therein. However, a gap is defined between the sections and affects the operation of the folding shaft. Conventional folding shaft of umbrellas generally includes sections each have a circular cross section and the friction between the sections is significant. If the gaps between the circular sections are made large to reduce the friction and accommodate the spring of the opening device, the spring might not be installed in stable condition.
The present invention intends to provide a folding shaft for umbrellas and the sections of the folding shaft includes sections with polygonal shape and sections with circular section, the sections with polygonal shape and sections with circular section are retractably connected to each other in an alternative sequence so as to obtain minimum gap between sections.
The present invention relates to a folding shaft for umbrellas and the shaft comprises a first section having a circular cross section, a second section movably mounted to the first section and a third section movably mounted to the second section. The second section includes an enclosed cross section which includes a plurality of straight sides and a plurality of first curved portions connected between the straight sides. The third section includes an enclosed cross section which includes a plurality of inward curved sides and a plurality of second curved portions connected between the inward curved sides, and the inward curved sides of the third section are located corresponding to the straight sides of the second section. The second curved portions of the third section are located corresponding to the first curved portions.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.
a shows a cross section of the three sections in
a shows the cross section of the central section in
b shows the cross section of the intermediate section in
c shows the cross section of the external section in
a shows a cross section of the five sections in
a shows the cross section of the central section in
b shows the cross section of the first intermediate section in
c shows the cross section of the second intermediate section in
d shows the cross section of the third intermediate section in
e shows the cross section of the external section in
a shows the sections of the shaft are in extended status, and
b shows the four sections of the third embodiment of the folding shaft of the present invention.
Referring to
The gaps between the sections of the folding shaft is controlled to be the minimum so that the folding shaft can be made smaller, and the gaps also ensure that the spring can be well installed in the folding shaft to ensure the operation of the folding shaft.
While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
Number | Date | Country | Kind |
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2006 1 0157833 | Dec 2006 | CN | national |
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Number | Date | Country | |
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20080149153 A1 | Jun 2008 | US |