Patent Publication Number: US-2003226929-A1

Title: Holding device for spare string trimmer line spools with slotted inner cavities

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates in general to string trimmers used to cut grass and weeds. In particular, the invention relates to a holding device comprising a single member for holding a spare spool of trimmer line on the string trimmer while the string trimmer is in use.  
       BACKGROUND OF THE INVENTION  
       [0002] Without limiting the scope of the invention, its background is described in connection with holding a spare spool of trimmer line on an operating string trimmer.  
       [0003] String trimmers are the most popular means to cut grass and weeds where larger machines such as lawn mowers cannot go, such as in ditches and along borders. String trimmers use a consumable plastic filament or line to accomplish the cutting action. Since this line is constantly abraded during the operation of the string trimmer, most string trimmers employ a spool that holds a quantity of line and dispenses it to allow continuous operation of the string trimmer.  
       [0004] There are no means to verify the quantity of line present on the spool without partially disassembling the spool assembly. Many operators of string trimmers, particularly commercial landscapers, use string trimmers a significant distance from where spare spools of line are stored. The size of these spare spools is large enough that they will not easily fit in the pockets of pants. The combination of these factors commonly results in wasted time and effort from walking back to where the spare spools of line are kept.  
       [0005] A popular string trimmer line spool design that is used by a number of manufacturers utilizes a slotted inner cavity as a means of holding the spool in the rotating head of the string trimmer.  
       [0006] As such, a need exists for a holding device for spare string trimmer spools with a slotted inner cavity, which provides a means to attach a spare spool of line to a string trimmer while the trimmer is in use.  
       SUMMARY OF THE INVENTION  
       [0007] The present invention provides for a holding device for spare string trimmer line spools.  
       [0008] Disclosed in one embodiment is a holding device for spare string trimmer line spools. The holding device, shown in FIG. 1, comprises a clamp body attached to a pair of support arms. The clamp body consists of two curved clamp arms that are arranged so that a resulting hole for the trimmer shaft, and clamp opening, forms a spring-action clamp when made of a resilient material.  
       [0009] A spool is shown for reference in FIG. 2. The reference spool is hollow, with a spool inner cavity having a cylindrical shape. A pair of grooves in the spool inner cavity are oriented parallel to the axis of the spool inner cavity and on opposite sides of the spool inner cavity. The spool inner cavity is open at one end, and closed at the other. The interior of the closed end of the spool inner cavity forms an upper surface of the inner spool cavity.  
       [0010] The support arms, project from the upper surface of the clamp body. These support arms have curved surfaces that allow the support arms to fit inside the spool inner cavity. The center area between the support arms is cut away to save material, except for a cross bar that acts to prevent the support arms from deflecting towards each other during use. Each support arm has a round lug located near its top surface. These round lugs project from the curved surface of the support arms a distance slightly less than the depth of the grooves in the spool inner cavity, and have a diameter slightly less than the width of the grooves in the spool inner cavity. During use, these lugs each engage the grooves in the spool inner cavity.  
       [0011] The spool holder is placed on a string trimmer shaft by positioning the clamp opening over the string trimmer shaft as shown in FIG. 4 a , and then forcing the spool holder manually towards the centerline of the string trimmer shaft. The clamp arms will deflect to allow the clamp opening to enlarge sufficiently to slip over the string trimmer shaft as shown in FIG. 4 b . Once on the string trimmer shaft, the slightly smaller inside diameter of the hole for trimmer shaft compared to the outside diameter of the trimmer shaft provides an interference fit that securely holds the spool holder in place on the shaft.  
       [0012] Each groove in the spool inner cavity has an offset in the groove in the spool inner cavity located at the end of the groove in the spool inner cavity closest to the upper surface of the inner spool cavity. These offsets in the groove in the spool inner cavity are at a nearly right angle to the inner spool cavity grooves. These offsets in the groove in the spool inner cavity are not parallel to the upper surface of the spool inner cavity, but are inclined slightly with a relief at the end of each offset in the groove in the spool inner cavity.  
       [0013] The spool is placed in the spool holder by first aligning the round lugs with the grooves in the spool inner cavity as shown in FIG. 3. The spool is pushed towards the top surface clamp body until the top surfaces the support arms contact the upper surface of the spool cavity. At this point, the round lugs, are lined up with the offset in the groove in the inner spool cavity. The spool is then twisted counterclockwise so that the round lugs enter the offset in the groove in the spool inner cavity. As the spool is twisted, and the round lugs move to each end of the offset in the groove in the inner spool cavity, the incline in the offset in the groove in the inner spool cavity, cause the ends of the support arms to be forced against the upper surface of the spool inner cavity, until the round lugs enter the relief in the offset in the groove in the inner spool cavity. The relief relieves the interference fit produced by the incline in the offset in the groove in the inner spool cavity, and causes the spool to be positively retained on the spool holder.  
       [0014] The spool is removed from the spool holder by twisting the spool clockwise and lifting it off of the spool holder.  
       [0015] An advantage of the present invention includes the ease with which a spool can be placed into or be removed from the holder, and the positive way that the spool is held. Other advantages of the present invention include its relatively small size, and the ease of manufacturing and the low costs associated therewith.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0016]FIG. 1 is a perspective view of the preferred embodiment of the spare spool holder.  
     [0017]FIG. 2 is a perspective view of a string trimmer spool for reference.  
     [0018]FIG. 3 is a perspective view of a string trimmer spool being installed on the spare spool holder.  
     [0019]FIGS. 4 a  and  4   b  are perspective views of the spare spool holder being installed on the string trimmer shaft.  
     [0020]FIG. 5 is a perspective view of an alternate embodiment of the spare spool holder with an alternate clamping arrangement.  
     [0021]FIG. 6 is a perspective view of an alternate embodiment of the spare spool holder with clips to hold the trimmer line ends in place.  
                               Refereoce Numerals Used In The Drawings                                        18   Spool Holder, Preferred Embodiment       20a, 20b   Round Lug       21   Top Surface of Clamp Body       22a, 22b   Support Arm       23a, 23b   Curved Surfaces of Support Arms       24   Cross Bar       25   Clamp Body       26a, 26b   Clamp Arm       27a, 27b   Top Surfaces of Support Arms       28   Clamp Opening       30   Hole For Trimmer Shaft       32   Spool (Prior Art, For Reference Only)       33a, 33b   Relief       34   Spool Inner Cavity       36a, 36b   Groove in the Spool Inner Cavity       38   Upper Surface of the Inner Spool Cavity       40a, 40b   Offset in the Groove in the Spool Inner Cavity       42   String Trimmer Shaft (Prior Art, For Reference Only)       44   Spool Holder, Alternate Embodiment, clamping arrangement       46   Fastener Hole, Alternate Embodiment       48   Split Collar, Alternate Embodiment       50   Spool Holder, Alternate Embodiment, Line end holder clips       52a, 52b   Clip, line end holder       54a, 54b   Gap, line end holder clip                  
 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0022] The present invention provides for a holding device for spare string trimmer line spools.  
     [0023] Disclosed in one embodiment is a holding device for spare string trimmer line spools. The holding device, shown in FIG. 1, comprises a clamp body  25  attached to a pair of support arms,  22   a  and  22   b . The clamp body  25  consists of two curved clamp arms  26   a  and  26   b  that are arranged so that a resulting hole for the trimmer shaft  3 , and clamp opening  28 , forms a spring-action clamp when made of a resilient material.  
     [0024] A spool  32  is shown for reference in FIG. 2. The reference spool  32  is hollow, with a spool inner cavity  34  having a cylindrical shape. A pair of grooves in the spool inner cavity  36   a ,  36   b  are oriented parallel to the axis of the spool inner cavity  34  and on opposite sides of the spool inner cavity  34 . The spool inner cavity  34  is open at one end, and closed at the other. The interior of the closed end of the spool inner cavity  34  forms an upper surface of the inner spool cavity  38 .  
     [0025] The support arms,  22   a  and  22   b  project from the upper surface  21  of the clamp body  25 . These support arms  22   a  and  22   b  have curved surfaces  23   a  and  23   b  that allow the support arms  22   a  and  22   b  to fit inside the spool inner cavity  34 . The center area between the support arms  22   a  and  22   b  is cut away to save material, except for a cross bar  24  that acts to prevent the support arms  22   a  and  22   b  from deflecting towards each other during use. Each support arm  22   a  and  22   b  has a round lug  20   a  and  20   b  located near its top surface  27   a  and  27   b . These round lugs  20   a  and  20   b  project from the curved surface of the support arms  23   a  and  23   b  a distance slightly less than the depth of the grooves in the spool inner cavity  36   a  and  36   b , and have a diameter slightly less than the width of the grooves in the spool inner cavity  36   a  and  36   b . During use, these lugs  20   a  and  20   b  each engage the grooves in the spool inner cavity  36   a  and  36   b.    
     [0026] The spool holder  18  is placed on a string trimmer shaft  42  by positioning the clamp opening  28  over the string trimmer shaft  42  as shown in FIG. 4 a , and then forcing the spool holder  18  manually towards the centerline of the string trimmer shaft  42 . The clamp arms  26   a  and  26   b  will deflect to allow the clamp opening  28  to enlarge sufficiently to slip over the string trimmer shaft  42  as shown in FIG. 4 b . Once on the string trimmer shaft  42 , the slightly smaller inside diameter of the hole for trimmer shaft  30  compared to the outside diameter of the trimmer shaft  42  provides an interference fit that securely holds the spool holder  18  in place on the shaft  42 .  
     [0027] Each groove in the spool inner cavity  36   a  and  36   b  has an offset in the groove in the spool inner cavity  40   a ,  40   b  located at the end of the groove in the spool inner cavity  36   a  and  36   b  closest to the upper surface of the inner spool cavity  38 . These offsets in the groove in the spool inner cavity  40   a ,  40   b  are at a nearly right angle to the inner spool cavity grooves  36   a  and  36   b . These offsets in the groove in the spool inner cavity  40   a ,  40   b  are not parallel to the upper surface of the spool inner cavity  38 , but are inclined slightly with a relief  33   a ,  33   b  at the end of each offset in the groove in the spool inner cavity  40   a ,  40   b.    
     [0028] The spool  32  is placed in the spool holder  18  by first aligning the round lugs  20   a  and  20   b  with the grooves in the spool inner cavity  36   a  and  36   b  as shown in FIG. 3. The spool  32  is pushed towards the top surface clamp body  21  until the top surfaces the support arms  27   a  and  27   b  contact the upper surface of the spool cavity  38 . At this point, the round lugs,  20   a  and  20   b  are lined up with the offset in the groove in the inner spool cavity  40   a  and  40   b . The spool  32  is then twisted counterclockwise so that the round lugs  20   a  and  20   b  enter the offset in the groove in the spool inner cavity  40   a  and  40   b . As the spool  32  is twisted, and the round lugs  20   a  and  20   b  move to each end of the offset in the groove in the inner spool cavity  40   a  and  40   b , the incline in the offset in the groove in the inner spool cavity  40   a  and  40   b , cause the ends of the support arms  27   a  and  27   b  to be forced against the upper surface of the spool inner cavity  38 , until the round lugs  20   a  and  20   b  enter the relief  33   a ,  33   b  in the offset in the groove in the inner spool cavity  40   a  and  40   b . The relief  33   a ,  33   b  relieves the interference fit produced by the incline in the offset in the groove in the inner spool cavity  40   a  and  40   b , and causes the spool  32  to be positively retained on the spool holder  18 .  
     [0029] The spool  32  is removed from the spool holder  18  by twisting the spool  32  clockwise and lifting it off of the spool holder  18 .  
     [0030] An advantage of the present invention includes the ease with which a spool can be placed into or be removed from the holder, and the positive way that the spool is held. Other advantages of the present invention include its relatively small size, and the ease of manufacturing and the low costs associated therewith.  
     DETAILED DESCRIPTION OF ALTERNATE EMBODIMENTS  
     [0031] One alternate embodiment provides for the clamp arms  26   a  and  26   b  described in the preferred embodiment to be replaced with a clamping arrangement utilizing a split collar  48  and a fastener hole  46  to accommodate a threaded fastener as shown in FIG. 5. This embodiment provides a more positive clamping action at the expense of higher manufacturing cost and reduced ease of installation.  
     [0032] Another alternate embodiment provides for trimmer line end clips  52   a  and  52   b  as shown in FIG. 6. These trimmer line end clips  52   a  and  52   b  provide a means of securing the loose ends of trimmer line that extend downward from the spool  32  when it is filled with trimmer line. The trimmer line is pushed into a gap  54   a  and  54   b  between the trimmer line end clips  52   a  and  52   b  and the clamp body  25 . The trimmer line end clips  52   a  and  52   b  are arranged so that the trimmer line is pulled out of the gaps  54   a  and  54   b  as the spool  32  is twisted clockwise to remove it from the spool holder  50 . This embodiment prevents the loose ends of trimmer line from unwinding off of the spool  32  while the trimmer is in use.