Abstract:
A trimmer can be converted from an existing cutting medium to an alternative tool without requiring removal of the trimmer head. A common upper receiver head, as sold by an original equipment trimmer manufacturer, incorporates design provisions to snugly allow an easy/comfortable fit for a series of uniquely adaptable and convertible cap attachments such as, monofilament bump systems, unique molded or shaped flexible line blades with optional cutting swath diameters, as well as other helpful devices that perform different functions beyond just cutting grass.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/946,568, filed Feb. 28, 2014, the entire content of which is herein incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    (Not Applicable) 
       BACKGROUND OF THE INVENTION 
       [0003]    The invention relates to grass trimmers and, more particularly, to a convertible cap and head system for a trimmer that enables it to be converted from its original cutting medium to an alternative cutting medium or tool by changing at the head area, and not by changing the entire lower boom as currently practiced. 
         [0004]    Handheld grass trimmers, powered by gas and or AC/DC electricity, have been popular outdoor tools for trimming grass and weeds along a variety of edges and into terrain where conventional mowers cannot practically or easily reach. Since their inception in the early 70&#39;s, trimmers have been largely confined to trimming light weeds and grass with monofilament string or nylon line (and/or metal/brittle plastic blades for heavier vegetation) as the primary cutting system used. Because of the high speeds required to reach the low mass mono line&#39;s cutting capability, high operating stresses cause continual breakage and consequently, manual or mechanical replenishment systems are needed to continuously feed or replenish the cutting line. Over the years, there have been limited improvements, but no real solution to the highly frustrating issues caused by weak and overstressed line. 
         [0005]    In addition to the heavy and cantilevered weight the operator has to carry and maneuver, the trimmer, for the most part, must be handheld by the operator for many reasons because hitting the ground causes added line stresses to ultimately cause line breakage. Hitting abrasive surfaces should be avoided because it accelerates wear and breakage; hitting rocks or loose impediments should be avoided where possible to minimize dangerous thrown objects; only to name a few. Therefore, grass trimmers had to be ‘hand held’ to maneuver above and around the obstacles and impediments. 
         [0006]    There are times when the operator may prefer to rest the spinning head and extended cutting line directly onto the ground to cut closer, or to try to cut at a given height, or perhaps for weight relief, but a number of problems, in addition to those related above, emerge as a result. Such problems may include thrusting, scalping, and other such control issues, as well as rapid line wear and breakage. Additionally, the surfaces rubbing onto the abrasive ground cause wear to the bump knob systems to become inoperable as the bumping knob grinds away. 
         [0007]    Needless to say, handheld trimming can be a frustrating process with ‘string’ or ‘flexible line’ being the number one problem users have faced since the inception of the ‘string’ trimmer. For years, users have been constantly seeking solutions, as many new and different developments have offered promise toward a solution, but to no avail, mono line problems still remain the major problem. So very often, users want to try different systems that promise even the slightest improvement. To install such new innovations, however, removal of the old system becomes the requirement before the new system can be tested on the user&#39;s trimmer, or such replacements may likely not be properly installed to maintain the operator protection systems originally built into the trimmer. 
         [0008]    Different users have different preferences for different cutting systems. For example, they may be satisfied with the original mono system provided with the original trimmer from the manufacturer which may likely include a popular bump type line replenishment system. On the other hand, due to poor line life and bump head complexities, they may want to try new innovative cutting systems with their own specific advantages. In either case, each original system, more than likely, must be removed in total and replaced by the other. There are generally no interchangeable or commonly used component parts. The entire system needs to be removed to make room for the replacement system to be mounted to the trimmer&#39;s arbor. In most cases, removal of the existing system is required to further assure the cutting line plane regulations with respect to the rear grass shield to be maintained to ANSI safety specifications. 
         [0009]    Converting from the common manufacturer&#39;s grass trimmer mono filament line heads presents a great challenge if the user wants to change to another cutting system. In many cases, the original heads are permanently affixed, making it impossible to remove the old head system to adapt another system. Even if the old system is removable, the degree of difficulty can be extensive. Some systems, for example, use extra fastening and securing means such as more permanent retainer rings while others have special uncommon reverse threading needed for self-tightening purposes on different rotational directions. For example, a counterclockwise rotating trimmer needs left hand threads for self-tightening; otherwise, it could easily unscrew itself during decelerations. 
         [0010]    Further, when removing the old head, it is a requirement to hold or lock the arbor so the head can be unscrewed from the arbor threads. Some trimmers do not have a visible means to hold the arbor, while others simply cannot be removed. These complexities have discouraged many customers incapable or unwilling to perform the needed conversion, thus denying the option of the new innovation. This is a very real and broad problem which this technology addresses. 
         [0011]    It is also worth noting that conventional monofilament line does not cut grass to ‘quality’ conditions. It mashes and rips grass blades only to become ‘sun brown’ at these frazzled tips. The mono cutting line also pushes air and grass down and away from the cutting lines. 
         [0012]    There is a further developing need for this easier ‘conversion’ innovation with newer developing technologies such as the trimmer&#39;s ground supporting glider, which now levels the cut while sharp leading flexible blades cut cleanly as they also lift air which lifts grass to effectively aid in cleaner cutting and rotary mowing. See, for example, U.S. patent application Ser. No. 14/280,916, the contents of which are hereby incorporated by reference. Additionally, a whole new series of benefits of the glider and line blade technologies will be further enhanced or emphasized with the contribution from the subject convertibility art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    It is now beneficial to offer numerous choices to satisfy the many added and extended trimmer uses now offered with these new inventions and technologies. 
         [0014]    A common upper receiver head, as sold by an original equipment trimmer manufacturer, would incorporate design provisions to snugly allow an easy/comfortable fit for a series of uniquely adaptable and convertible cap attachments such as, mono bump systems, unique molded or shaped flexible line blades with optional cutting swath diameters, as well as other helpful devices that perform different functions beyond just cutting grass. 
         [0015]    The convertible cap from mono line to line blades, for example, would be designed to fit snugly into the upper receiver head while its finger tabs, in this case, click into open window slots within the receiver head. To remove the cap, the finger tabs of the cap are deflected inward to clear away from the window slots. 
         [0016]    It would also be most helpful to have an upper head receiver that can utilize common mono line spools and knob components. This would allow interchangeability of existing components (the more common spools and knobs) already in use, to save additional start-up and tooling expense to both manufacturers and users. For example, the receiver head may contain the internal projections needed for the mono line bump advancing mechanism, which remain clear of interference with any other lower cap attachment options. 
         [0017]    Additionally, a removable arbor adapter may be provided for use with conventional knobs to retain the common line spool. It further enables either a bolt-on cap, or finger tab retention mechanisms to give optional attaching means for other optional and useful cap designs. This arbor adapter device is a part of the convertibility solution, as it enables different cap clamping options. It connects or disconnects directly to or from the driving arbor and can be any shape or length to support the particular needs of the attachment option. When the arbor adapter is used, the finger tab window in the head receiver remains open while offering a view when the internal line spool is installed to visually determine how much line remains. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which: 
           [0019]      FIG. 1  shows exploded views for an exemplary convertible head system that provides for converting an existing bump line monofilament string cutting medium to a cap-mounted line blade cutting medium with a glider attachment; 
           [0020]      FIG. 2  shows assembly views of a converted cap supporting line blades; 
           [0021]      FIG. 3  shows an assembly utilizing an arbor adapter; 
           [0022]      FIG. 4  shows an assembly for an alternative tool for use with the trimmer; 
           [0023]      FIGS. 5-7  show components for a convertible cap including posts for supporting line blades in multiple orientations; 
           [0024]      FIGS. 8-10  show securing arrangements for line blades; and 
           [0025]      FIG. 11  is a close-up view of a finger tab of the convertible cap. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]      FIG. 1  is an exploded view showing an existing monofilament line bump feed system  10  convertible to a line blade system  12  without requiring removal of an entire trimmer head. 
         [0027]    An arbor  14  is conventionally driven by a motor unit or the like and driving components (not shown). Any suitable motor unit and driving components can be used with the convertible head system according to preferred embodiments. An upper head  16  is fixed to the arbor  14  for rotation with the arbor  14 . The upper head  16  is provided with one or more, preferably two, finger tab windows  18  for connecting and securing the trimmer components. 
         [0028]    With continued reference to  FIG. 1 , the assembly for a monofilament cutting line may include a spring  20  interposed between a line spool  22  and the upper head  16 , where the monofilament line  24  is wound on the spool  22 . A bolt  26  secures the spool  22  through a line retainer  28  and a washer  30 . A bump cap  32  is cooperable with the spool  22 , and a cap  34  encloses the assembly. The cap  34  includes one or more finger tabs  36 , preferably two, that snap into engagement with the finger tab windows  18  in the upper head  16 . 
         [0029]    The monofilament line assembly  10  can be converted to the line blade system  12  without removing the upper head  16  from the arbor  14 . The monofilament line system  10  is readily removed by releasing the cap  34  from the finger tab windows  18  in the upper head  16 . With the components removed, the line blade system  12  can be attached to the upper head  16 . The line blade system  12  includes a main convertible cap  38  supporting a plurality of line blades  40  with a nut  42  and bearing  44  interposed between the cap  38  and the upper head  16 . The main convertible cap  38  similarly includes finger tabs  36  engageable in the finger tab windows  18  of the upper head  16 . The finger tabs  36  are deflectable via an active hinge  37  between the finger tabs  36  and the cap  34 . In the embodiments shown in  FIG. 1 , an optional glider assembly  46  is also attached and includes a disk-shaped glider  48  disposed on a ground side of the convertible cap  38  with nuts  50 , a spacer  52  and a bearing  54  interposed between. The assembly is secured by a bolt  56  or other suitable connecting structure. 
         [0030]    The equipment manufacturer may thus initially provide the trimmer with the monofilament line system  10 . With the upper head adaptable for attachable cap options, an alternative monofilament line, or the line blade system  12  shown in  FIGS. 1 and 2 , and/or other tools can be interchangeably attached. Since the upper head  16  utilizes common attaching features, the upper head  16  in  FIG. 1  may differ in size or shape as in upper head  16 ′ shown in  FIG. 2  or  FIG. 3 , and does not need to be removed from the arbor  14 . As a consequence, converting from one assembly to another can be readily accomplished. The convertible cap system preferably encompasses a family of systems to accommodate varying existing systems including line bump systems, centrifugal feed systems, manual systems, and the like typically used with monofilament line. Of course, if the user decides to reassemble the monofilament line system  10 , the construction of the upper head  16  and the convertible head assembly provides for easy re-conversion. 
         [0031]    With reference to  FIG. 3 , an arbor adapter  58  may be coupleable with the arbor  14 . The arbor adapter  58  serves to extend the arbor  14  such that a different style or type of trimmer spool  22  can be clamped or connected (without use of finger tabs) to a receiver head  16 ′ by a threaded knob  17 . When the trimmer spool  22 , the arbor adapter  58 , and the knob  17  are removed from the upper head  16 ′, the main line blade convertible cap  38  is then attached to the upper head  16 ′ by the finger tabs  36  engaging the windows  18  of the upper head  16 ′. When the spool  22  is clamped to the arbor  14  with the arbor adapter  58  and the knob  17 , the finger tab windows  18  in the upper head  16 ′ are open, and the existing trimmer spool and corresponding components are viewable through the finger tab windows  18 . 
         [0032]    Still other alternative caps may be interchangeable with the main convertible cap  38 , where the alternative convertible caps support tools for use with the trimmer. Exemplary tools may include a sprinkler head cutter, a rotary broom/scrubber, and the like.  FIG. 4  shows an alternative convertible cap  138  with a sprinkler head cutter. 
         [0033]      FIGS. 5-7  show details of the main convertible cap  38 . As shown, the convertible cap  38  includes a plurality of line blade connectors  60  and blade outlets  62 . The line blades  40  are connected to the line blade connectors  60  in the convertible cap  38  and are positioned through the line blade outputs  62 . It is preferable in the line blade assembly to have an even number of outlets (e.g., two or four outlets) for balance to be maintained with wear throughout the life of the extended line blade. The line blade connectors  60  may include line blade posts  64  or hood posts  64  that are sized and shaped to receive and retain connector eyelets  66  formed at proximal ends of the line blades  40 . In cooperation with the upper head  16  also clamping onto the line blades  40 , the additional hooded posts  64  retain the line blades  40  in at least two locations. With the use of finger tabs  36 , cap retention is not dependent on a threading direction, and the assembly works for multi-directional rotation (clockwise or counterclockwise). Additional flip-flop posts can be included to provide options for line blade directional benefits at the cutting zone. The line blades can be oriented with a leading sharp edge or a leading aero edge to produce updraft or down draft, respectively. Updraft will lift grass for rotary mowing, whereas down draft will blow debris away. In one embodiment, the line blade directional posts are marked “M” for mow and “T” for trim for the line blade assembly (see  FIGS. 6 and 7 ). In a preferred construction, each of the line blade connectors  60  includes two line blade posts  64  for each of the line blade outlets  62 . In an exemplary configuration, using a molded line having an aerodynamic cross-section, alternative advantages can be achieved by varying a leading edge of the aerodynamic cross-section. The two line blade posts  64  for each of the line blade outlets  62  enable each of the line blades  40  to be alternately oriented. In the exemplary configuration shown in  FIG. 6 , the line blades  40  are secured in a first orientation for a trimming operation, and in  FIG. 7 , the line blades  40  are secured in a second orientation for a mowing operation. The exemplary configuration shown in  FIG. 5  also includes the glider assembly  46 . Other configurations are described in commonly-owned U.S. patent application Ser. No. 12/607,548, the contents of which are hereby incorporated by reference. 
         [0034]    With the system of the preferred embodiments, the line blades  40  are loaded into the cap  38  and not into the head  16 . Compared to the older line blade system, the user does not have to hold the trimmer while loading line blades and can select a larger swath diameter head more suited to perform different jobs. The convertible head/cap combination can be used with any conceivable attachment, with or without a glider. There are also provisions for mounting the glider disc and bearing shaft. Although not essential with the common provision involving grass shield designs, it is preferable for the upper head/cap split to be located at or near the monofilament line eyelet line plane to maintain the same line plane for adequate and proper functioning of the shield&#39;s protective flange. The optional use of the glider assembly further enhances the many benefits of the convertible system. For example, the glider assembly enables the trimmer to be operated while it rests directly on the ground. When used with the glider assembly, a single or double bearing system can be provided. The single bearing system includes a bearing within the glider or cap. The bearing is set into either the cap or glider with plate retainers and screws or is preferably molded into the cap or glider. 
         [0035]    It is desirable for the line blade connectors to include at least two securing places for each of the line blades  40 . In the line blade embodiments, the lower flange of the upper head  16  becomes an upper clamping zone to physically hold the line blades  40  in their respective slots. See  FIGS. 8 and 9 . That is, the outer rim of the upper head above the outlet can sandwich the line blades between the head and the cap, while allowing its swing radius support. Exemplary structures may also include specially designed retaining posts  164  as shown in  FIG. 8 . The retaining post  164  includes an upper flange  165  that positively engages the eyelet  66  of the line blades  40 . The retaining posts  164  firmly secure the line blades  40  into a secure position and maintain its support within its respective channel leading to the outlet  62 . Other alternatives are shown in  FIGS. 9 and 10 , including a channeled outlet  162 . 
         [0036]    Preferably, the upper head  16  and convertible cap are injection molded parts using conventional molding technology with reasonably inexpensive and durable nylon copolymers, either with or without glass reinforcement fibers for added strength as needed. 
         [0037]    With reference to  FIG. 11 , to assist with removing the convertible cap assembly when desired, a screwdriver slot  68  is formed at the end of the finger tabs  36  to enable a tool (e.g., screwdriver) to deflect and disengage the tabs  36  to remove the cap for line blade replacement and reloading. 
         [0038]    In use, a trimmer head can be converted from one cutting medium to an alternative tool using the convertible cap assembly of the preferred embodiments. In order to convert the trimmer head, the lower head and the one cutting medium (e.g., spooled monofilament line) are removed. The alternative tool is secured in the convertible cap, and the convertible cap is secured to the upper head. As noted, in one construction, the convertible cap includes line blade connectors and line blade outlets, where the alternative tool includes a plurality of line blades. The step of securing the alternative tool to connectors in the convertible cap is practiced by securing the line blades to the line blade connectors in the convertible cap and positioning the line blades through the line blade outlets. The glider assembly may be secured at the user&#39;s option. 
         [0039]    The system and methods according to the preferred embodiments enable an existing monofilament line to be converted to line blades with or without a glider assembly without the user having to remove the original head for the new replacement option. The convertible cap can be used with molded or formed line blades to achieve sharp/aerodynamic leading edge with updrafts. The resulting construction can achieve flexible line blade rotary mowing without head removal for contour mowing and general trimming. The glider assembly provides for ground supported thrust-free grass trimming, still without requiring removal of the trimmer head. The construction extends work functions of the trimmer beyond cutting vegetation with different attachments. 
         [0040]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.