Abstract:
A hub attachment for a rotating drive shaft of a hand-held, portable string cutter for grass and weeds having a centrally located cylindrical anchor lug for a nylon cutting line which is held in a retainer line anchor that is in turn positioned in the semi-cylindrical cavity of the hub attachment. The retainer line anchor is provided with a latching tab that can be rotated from an unlatched position to a position in which the tab is removably attached to the hub.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 484,443 filed Feb. 21, 1990 now abandoned, which in turn was a continuation of application Ser. No. 337,876 filed Apr. 14, 1989 now abandoned which in turn was a continuation in part of application Ser. No. 264,389, filed Oct. 31, 1988, now U.S. Pat. No. 4,987,681, issued Jan. 29, 1991 for which benefit under 35 U.S.C. §120 is claimed. 
     The present invention relates to a hub attachment for a drive shaft of a cordless grass/weed trimmer of the type shown in my copending patent application Ser. No. 264,389 filed Oct. 31, 1988 and entitled Hand Held Cordless Grass/Weed Trimmer. 
    
    
     BACKGROUND OF THE INVENTION 
     Previous constructions of the so-called nylon string grass and weed trimmer were not dynamically balanced for optimum performance while at the same time securely retaining the cutting line in the cutting chamber. The present invention overcomes that drawback by securely retaining the cutting line and centering it in the cutting chamber for optimum dynamic balance and performance. 
     It is another object of the present invention to provide a hub and cutting line arrangement which is so constructed and arranged in order to minimize the weight of mass of the rotating assembly, thus reducing the motor load especially during start-up of the groomer-trimmer in order to permit the hub assembly to achieve full rotational speed quickly. 
     It is a further object of the present invention to provide a detachable hub arrangement for the drive shaft of a grass/weed trimmer in which rapid replacement of cutting lines can be made without the use of tools. 
     It is a further object of the present invention to provide a line retaining mechanism for a detachable hub in which a spring-loaded mechanical interlock is provided which prevents the unintentional unlatching of the cutting line from the hub attachment. 
     It is an object of the present invention to provide a nylon cutting line having a centrally located cylindrical anchor lug which is inserted into a cylindrical cavity of a hub, and is provided with latching member for securely holding the centrally located lug in the cavity. The nylon cutting line projects from either end of the cylindrical anchor lug, the cutting line being securely held by being crimped on the anchor lug positioned in the hub cavity. Consequently, the nylon cutting lines can be easily and rapidly replaced by releasing the latching means and placing another anchor lug with projecting lines in the cylindrical cavity of the hub. 
    
    
     In order that the present invention will be more clearly understood, it will now be disclosed in greater detail with reference to the accompanying drawings in which: 
     FIG. 1 is an exploded perspective view showing the anchor lug/cutting line assembly positioned within the cylindrical cavity, of the line anchor retainer, and said anchor lug being centrally crimped around said cutting line. 
     FIG. 2 is a perspective view of the hub attachment and retainer-line anchor therein with a tab, shown in its unlatched position. 
     FIG. 3 is a perspective view of the hub attachment with the retainer line anchor and cutting line with the tab in its latched position. 
     FIG. 4 is a top plan view of the hub thereof and, 
     FIG. 5 is a sectional view taken along the lines 5--5 of FIG. 4. 
     FIG. 6 is another top plan view of the assembly constituting the present invention showing the tab in its latched position, as it secures the line anchor/cutting line assembly. 
     FIG. 7 is a sectional view of the hub attachment with the locking tab in its unlatched position. 
     FIG. 8 is a sectional view taken along the lines 8--8 of FIG. 6 showing the tab in its latched position. 
     FIG. 9 is a side elevational view of the retainer line anchor as seen in FIG. 7. 
     FIG. 10 is a view taken along the lines 10--10 of FIG. 9. 
     FIG. 11 is an alternate construction of the retainer line anchor. 
     FIG. 12 is a front elevational view of the structure shown in FIG. 11. 
     FIG. 13 is the cylindrical anchor lug of FIG. 1 shown in a flat extended position. 
     FIG. 14 is a side elevational view thereof. 
     FIG. 15 is a view showing the anchor lug being centrally applied to a nylon cutting line and, 
     FIG. 16 is an enlarged view of the lug taken along the line 16--16 of FIG. 15. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows the assembly of the invention, in which the hub attachment for the shaft of a motor in a grass/weed trimmer is referred to by the numeral 10. The hub attachment is provided with a cylindrical attachment part 12 in which a motor shaft with a straight knurl pattern frictionally fits, as shown in phantom lines in FIGS. 5, 7 and 8. The hub attachment 10 is further provided with a semi-cylindrical cavity 14 in which is adapted to be inserted, a soft metal anchor lug 16 that is crimped centrally around the cutting line 18. An intermediate member for retaining the anchor lug 16 is utilized in the form of retainer line anchor 20, which is adapted to being inserted within the semi-cylindrical cavity 14 of the hub attachment before the metal anchor lug 16 and cutting line 18 is inserted therein. As seen in FIGS. 13-16, the soft metal anchor lug 16 initially is in a planar form with serrations 17 extending perpendicular to the longitudinal axis of the cutting line 18 when installed, as seen in FIGS. 15 and 16. It is also within the scope of the present invention to fabricate an anchor lug molded as an integral part with a cutting line, as well as a cutting line inserted through a closed cylindrical tube and then staked in order to retain the cutting line therein at a preselected location. 
     The cutting line 18 is preferably a nylon, mono-filament line of the type used in lawn and garden equipment commonly known as string trimmers. In the past it has been difficult to replace the nylon cutting line when it became partially severed so that it did not function properly. In that case, the hub assembly, which had a number of parts, would ordinarily be taken apart and the new nylon string length would be wound around the spool and re-inserted in the assembly. The present invention overcomes that difficulty of replacing the cutting line by providing pre-cut cutting lines together with a central anchor lug of any suitable material such as metal or plastic for centrally positioning the cutting line within the hub so that substantially identical lengths of cutting line portions extend out of opposite sides of the anchor lug, and thus dynamically balancing the same automatically. Means are provided for securely latching the cutting line within the hub assembly, which will be described in detail hereinafter. 
     Referring to FIGS. 1, 2 and 3, the retainer line anchor 10 is provided with a pivotal tab or release arm 22. When the metal anchor lug 16 together with the cutting line 18 is inserted within the retainer line anchor 20, and the latter placed in the cavity 14 of the hub attachment 10, as seen in FIG. 2, the tab 22 is shown in it&#39;s open position. The tab is then rotated 90 degrees as illustrated in FIGS. 3, 6 and 8 to securely lock the assembly together. 
     As seen in FIG. 5 the semi-circular cavity 14 is provided with a depression 14&#39; which accepts the correspondingly shaped bump 15 on an exterior surface of the retainer line anchor 20 in order to hold the anchor 20, lug 16 and cutting line 18 in the cavity 14. 
     The retainer line anchor 20 is particularly seen in FIGS. 9 and 10 showing the locking tab or release arm 22 in its open, or unloaded condition. The tab or release arm 22 is provided with a latch element 24 at the free end thereof in the form of a knob, while the retainer line anchor at the other end thereof has a spring-lock detent 26 which assumes a locked position when the retainer line anchor 20 is snugly inserted within the cavity or nest 14 of the hub 10. As seen in the Figures, the hub 10 is provided with two oppositely positioned strain relief wings 28 and 30 that function to distribute stress on a greater proportion of the cutting line as the motor shaft rotates. 
     As seen in FIGS. 11 and 12, an alternate version of the retainer line anchor 20 is shown, which is provided with three relief grooves 32 as well as an elongated curvilinear cut-out 34 to create the flex arm portion of the retainer. This alternate embodiment of the retainer line anchor 20 functions to distribute the flex pressure over a larger area and thus reduces the possibility of breaking or fracturing of the locking detent portion of the embodiment shown in FIGS. 7-10. 
     It should be noted that the release arm of the retainer line anchor 20 is provided with the locking detent for the purpose of being sprung into a matching void in the bottom of the hub cavity or nest, and thus forming a spring-loaded mechanical interlock that will prevent the release arm from unintentionally moving out of its latched or locked position. 
     In order to replace the nylon cutting line, the finger of a user is placed on the knob 24 of the release arm when it is in the latched condition as seen in FIG. 2, and pressure is applied in an upper direction to overcome the resistance provided by the locking detent or knob 24, thus causing the release arm 22 to become unlatched and rotate through an arc of 90 degrees, and consequently exposing the anchor lug 16 for easy removal and replacement. Thus, a new anchor lug 16 having cutting lines 18 projecting out of opposite ends of the anchor lug is inserted within retainer line anchor 20. 
     Referring now to FIGS. 13-16 in which is shown the soft metal anchor lug 16 which is originally in a flat planar form, as seen in FIGS. 13 and 14, but is bent into a cylindrical or tubular configuration as seen in FIGS. 15 and 16. It should be noted that the serrations 17 are present on the inside surface of the anchor lug, and when the anchor lug is securely crimped around the nylon line 18, the serrations firmly grip the nylon line to prevent slippage when the nylon line is rotated for cutting grass and vegetation. It should be noted that the serrations 17 are disposed in a plane perpendicular to the longitudinal axis of the cutting line 18. 
     The present string retaining hub assembly constitutes an arrangement which securely retains a cutting line, and also centers it in the cutting chamber for optimum dynamic balance and performance. Furthermore, the present arrangement provides for rapid replacement of the cutting line, when required, without the need for tools. 
     While the present invention has been disclosed with reference to two embodiments thereof, it will be apparent that many variations and modifications may be made therein, and it is therefore intended to cover each such variation and modification which falls within the true spirit and scope of the invention in the following claims: