Patent Publication Number: US-2015068568-A1

Title: Opening spring for multiple fold automatic open-close unbrella

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an opening spring for umbrellas, especially to an opening spring for multiple fold automatic open-close umbrellas. 
     Generally, a multiple fold automatic open-close umbrella includes an opening spring disposed in a shaft to providing power for extending the shaft while opening the umbrella, as shown in  FIG. 1 . A shaft  100  of a multiple fold automatic open-close umbrella includes an outer tube  101 , a middle tube  102  and an inner tube  103  sleeved in each other slidably from outside to inside in turn. An opening spring  200  is formed by spiral coils with a fixed outer diameter. When the opening spring  200  is mounted in the shaft  100 , its outer diameter is a bit smaller than an inner diameter of the inner tube  103 . The inner diameter of the middle tube  102  and the outer tube  101  is larger than that of the inner tube  103 . After being extended, the opening spring  200  in a larger space of the middle tube  102  and the outer tube  101  is easy to distort and this has negative effect on the elastic force of the opening spring  200 . Thus the opening spring  200  is unable to work properly and even get locked with other components in the shaft  100 . Both effects and service life of the opening spring  200  have been affected. 
     In order to make the multiple fold automatic open-close umbrella works properly, manufacturers usually increases the strength of the opening spring. But the force required to press and slide the shaft for closing the umbrella is also increased. For the elders and children, the umbrella is difficult to use. Refer to prior arts CN 202635844U, CN 202999585U, CN202774563U, CN202739035U etc., all try to overcome the above shortcomings. The opening spring with the same outer diameter is replaced by two springs with different outer diameters  301 ,  302 . The spring with larger outer diameter  301  and the spring with smaller outer diameter  302  are connected in series and are mounted vertically in a shaft  100 . As shown in  FIG. 2 , a connector  303  is disposed between the two springs  301 ,  302 . However, the two springs  301 ,  302  are produced respectively and the connector  303  is a new component. Moreover, the two springs  301 ,  302  are connected to the connector  303  respectively. Thus the structure is more complicated, the processing is more difficult, and the cost is increased. In addition, the number of dead coils of the coil springs  301 ,  302  is increased in order to connect to the connector  303 . 
     It is learned that a conventional one-part opening spring has a problem of lateral bending. Another conventional opening spring formed by two springs needs to connect the two springs by the connector  303 . In order to make the multiple fold automatic open-close umbrella have effects of normal use, easy fold and storage, and easy set-up, whether the opening spring has sufficient compression travel and elastic force should also be considered. Thus there is room for improvement and a need to provide a novel opening spring for multiple fold automatic open-close umbrellas that makes the umbrella use easily and work properly. 
     SUMMARY OF THE INVENTION 
     Therefore it is a primary object of the present invention to provide an opening spring for multiple fold automatic open-close umbrellas formed by a wound wire with a constant diameter and having a plurality of coils. According to the coil outer diameter, the coils are divided into coils are divided into coils are divided into a plurality of segments along the axial direction. The outer diameter of an upper segment of the coils is larger than the outer diameter of a lower segment of coils. A gradually changing part is disposed between two adjacent segments of coils. The coil outer diameter of the gradually changing part is reduced from top to bottom along the axial direction. Thereby the opening spring has simple structure, easy processing and low cost. While closing the umbrella, a smaller force is required to retract the umbrella. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view of a conventional multiple fold automatic open-close umbrella having an opening spring with a constant outer diameter of an embodiment according to the present invention; 
         FIG. 2  is a cross sectional view of another conventional multiple fold automatic open-close umbrella having two opening springs with different outer diameters of an embodiment according to the present invention; 
         FIG. 3  is a side view of an embodiment of an opening spring according to the present invention; 
         FIG. 4  to  FIG. 6  are partial enlarged views of different embodiments of a gradually changing part according to the present invention; 
         FIG. 7  is a cross section of an embodiment of a 3 fold automatic open-close umbrella in a close state according to the present invention; 
         FIG. 8  is a cross section of an embodiment of a 3 fold automatic open-close umbrella in an open state according to the present invention; 
         FIG. 9  is a cross section of an embodiment of a 4 fold automatic open-close umbrella in an open state according to the present invention; 
         FIG. 10  is a side view of another embodiment of an opening spring having two gradually changing parts according to the present invention; 
         FIG. 11  is a cross section of a 4 fold automatic open-close umbrella with the embodiment shown in  FIG. 10  according to the present invention; 
         FIG. 12  is a graph showing relationship between force and deformation of a conventional opening spring and an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENT 
     Refer from  FIG. 3  to  FIG. 11 , an opening spring of the present invention is used in a multiple fold automatic opening-closing umbrella. The multiple fold automatic opening-closing umbrella includes a shaft  1 , an umbrella rib assembly  2 , an opening spring  3 , a plurality of closing springs  4  and a control mechanism  5 . 
     Refer to  FIG. 7  and  FIG. 8 , the shaft  1  consists of an inner tube  11 , at least a middle tube  12  and an outer tube  13 . An umbrella handle  14  is connected to a bottom end of the inner tube  11  while the middle tube  12  is slid vertically around and engaged with the inner tube  11 . Similarly, the outer tube  13  is slid vertically around and engaged with the middle tube  12 . A top end of the outer tube  13  is disposed with an upper runner  15 . When there is one middle tube  12 , the shaft  1  is applied to a  3  fold umbrella as shown in  FIG. 7  and  FIG. 8 . While the number of the middle tube  12  is two, the shaft  1  is used in a 4 fold umbrella as shown in  FIG. 9  and  FIG. 11 . A first middle tube  12   a  is slid upward around and engaged with the inner tube  11  while a second middle tube  12   b  is slid upward around and engaged with the first middle tube  12   a . Moreover, the opening spring is applied to the 3 fold automatic opening-closing umbrella or 4 fold automatic opening-closing umbrella, as shown in figures, but the fold number of the umbrella is not limited. The opening spring of the present invention can also be modified and applied to other multiple fold automatic opening-closing umbrellas such as 5 fold automatic opening-closing umbrella. 
     The umbrella rib assembly  2  is composed of a top rib  21 , a lower branch rib  22 , a lower runner  23 , and a plurality of umbrella ribs  24 . An inner end of the top rib  21  is pivotally connected to the upper runner  15  of the shaft  1 . An inner end of the lower branch rib  22  is pivotally connected to the lower runner  23  so as to be slid around and engaged with the outer tube  13  of the shaft  1  while the other end thereof is pivotally connected to the top rib  21 . The umbrella ribs  24  are pivotally connected to one another, the top rib  21  and the lower branch rib  22 . The umbrella rib assembly  2  can also be modified according to changes of the umbrella ribs and the fold number of the automatic open-close umbrella. 
     A bottom end of the opening spring  3  is arranged at and supported by a lower part of the inner tube  11  of the shaft  1  while a top end of the opening spring  3  is disposed on and against the bottom of the upper runner  15  or the top of the outer tube  13 . 
     Each closing spring  4  is disposed between the top rib  21  and the lower branch rib  22  of the umbrella rib assembly  2 . The closing spring  4  can also be arranged at other positions of the umbrella rib assembly  2 . Elastic energy is stored in the closing spring  4  while the umbrella being opened by the opening spring  3 . Then the elastic energy is going to be used for closing the umbrella. 
     The control mechanism  5  includes a button  51  arranged at the umbrella handle  14 . By pressing the button  51  to release the locked state, the lower runner  23 , the tubes  13 ,  12   12   a ,  12   b  of the shaft  1 , and each umbrella rib of the umbrella rib assembly  2  are extended upward and outward due to elasticity of the opening spring  3  for opening the umbrella. Then press the button  51  again to release the umbrella ribs and tubes from the locking state for closing the umbrella. Next the umbrella handle  14  is pressed toward an umbrella cap  16  to compress the opening spring  3  and elastic energy is stored again for opening the umbrella next time. 
     Refer from  FIG. 3  to  FIG. 6 , the opening spring  3  is formed by a wounded wire with a constant wire diameter and having a plurality of coils  33 . The coils  33  include a plurality of continuous segments with different coil outer diameters axially. The outer diameter of an upper segment of coils is larger than the outer diameter of a lower segment of coils. The pitch of the upper segment of coils is larger than the pitch of the lower segment of coils. A gradually changing part  34  is arranged between two adjacent segments of coils. The gradually changing part  34  includes continuous coils  341 ,  342  wound inward and downward. The outer diameter of the coils  341 ,  342  is decreased from top to bottom. As shown in  FIG. 4  and  FIG. 5 , the outer diameter do of the coil  342  is ranging between an inner diameter of the coil  341  Di and an outer diameter Do of the coil  341 . Thus while the spring  3  being compressed axially, the coil  342  is axially compressed or axially against the coil  341 . As shown in  FIG. 6 , an outer diameter do of the coil  342  is smaller than the inner diameter Di of the coil  341 . While being compressed axially, the coil  342  is passed through the coil  341  axially, without radial interference. 
     Refer to  FIG. 3 ,  FIG. 7  and  FIG. 8 , when there is only one gradually changing part  34  in the opening spring  3 , the opening spring  3  includes an upper spring  35 , and a lower spring  36  in turn from top to bottom while the gradually changing part  34  is arranged between the upper spring  35  and the lower spring  36 . The top end of the upper spring  35  is against the bottom of the upper runner  15  or the top of the outer tube  13 . The bottom end of the upper spring  35  is connected to the top end of the lower spring  36  by the gradually changing part  34  while the bottom end of the lower spring  36  is against the bottom of the inner tube  11 . 
     Refer to  FIG. 10  and  FIG. 11 , when there are two gradually changing parts  34  in the opening spring  3 , the opening spring  3  includes an upper spring  35 , a middle spring  37 , and a lower spring  36  in turn from top to bottom. A gradually changing part  34   a  is arranged between the upper spring  35  and the middle spring  37 , and the other gradually changing part  34   b  is disposed between the middle spring  37  and the lower spring  36 . The top end of the upper spring  35  is against the bottom of the upper runner  15  or the top of the outer tube  13 . The bottom end of the upper spring  35  is connected to the top end of the middle spring  37  by the gradually changing part  34   a  while the bottom end of the middle spring  37  is connected to the top end of the lower spring  36  by the gradually changing part  34   b . The bottom of the lower spring  36  is against the bottom of the inner tube  11 . The coil outer diameter of the gradually changing part  34   a  is larger than the coil outer diameter of the gradually changing part  34   b.    
     Refer to  FIG. 7  and  FIG. 8 , when the opening spring  3  with one gradually changing part  34  is assembled with the shaft  1  of a 3 fold automatic open-close umbrella having one middle tube  12 , the gradually changing part  34  is located in the middle tube  12 . 
     Refer to  FIG. 9 , once the opening spring  3  with one gradually changing part  34  is assembled with the shaft  1  of a 4 fold automatic open-close umbrella having the first middle tube  12   a  and the second middle tube  12   b , the gradually changing part  34  is located in the second middle tube  12   b  that is the outermost middle tube. 
     Refer to  FIG. 11 , when the opening spring  3  with two gradually changing parts  34   a ,  34   b  is used in a is assembled with the shaft  1  of a 4 fold automatic open-close umbrella having the first middle tube  12   a  and the second middle tube  12   b , the upper gradually changing part  34   a  is located in the second middle tube  12   b  (the outermost middle tube) while the lower gradually changing part  34   b  is located in the first middle tube  12   a . Moreover, the coil pitch of the above gradually changing parts  34 ,  34   a , and  34   b  can be larger than or equal to the wire diameter d of the coil. 
     Due to the coil outer diameter of an upper part of the opening spring  3  larger than the coil outer diameter of a lower part of the opening spring  3 , the space between the opening spring  3  and each tube  13 ,  12 ,  12   a ,  12   b  of the shaft  1  is reduced. The spring deformation is reduced while opening/closing the umbrella. Moreover, the deformation of the opening spring  3  is less than that of a conventional one-part opening spring  200 . Thus the service life of the opening spring  3  is increased. 
     Besides 3 fold automatic open-close umbrella, the opening spring  3  of the present invention can also be applied to a multiple fold automatic open-close umbrella such as 4 fold automatic open-close umbrella or 5 fold automatic open-close umbrella. When the automatic open-close umbrella is 4 fold or 5 fold, there are at least two middle tubes  12   a ,  12   b  of the shaft  1 . The middle tubes are sleeved to each other from the center to the outermost slidably. When the opening spring  3  is 3-part/segment or above and including at least two gradually changing parts  34 , the gradually changing parts  34  from top to bottom are arranged in the middle tubes  12  ( 12   a ,  12   b  . . . ) from the outermost to the center correspondingly. 
     When manufacturers have special requirements in specification or functions, they can modify the outer diameter, the wire diameter, the pitch and the materials of the coil  33  of the opening spring  3  for providing the stroke and the spring constant required. 
     Refer to  FIG. 12 , the line L 1  represents the one-part opening spring  200  of a prior art while F 1  is an opening force (for the umbrella) and F 2  is a closing force. As to the line L 2 , it represents the opening spring  3  of the present invention while F 1  is an opening force and F 3  is a closing force. It is learned from the figure that the opening spring  3  of the present invention uses coils  34  with a smaller wire diameter for providing the same elastic opening force as the one-part opening spring  200  yet with smaller closing force. Thus the total length of the opening spring  3  is increased. Moreover, a cross section of the above embodiments of the opening spring  3  according to the present invention is a circle, but not limited  1   e , but not limited to. The cross section can also be oval (not shown in figure). 
     In summary, compared with conventional automatic open-close umbrellas, the opening spring  3  of the present invention has more simple structure so that the manufacturing is easier, the cost is reduced and the maintenance is more convenient. The structure of the opening spring  3  is an integrated spring having multiple segments. Thus the elastic force each segment/part needed is smaller than the elastic force of the conventional one-part opening spring. Thus a smaller force is required to slide the shaft while closing the umbrella. And the lateral deformation of the opening spring  3  is smaller than the lateral deformation of the conventional one-part opening spring  200  so that the service life of the opening spring  3  is increased. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.