Abstract:
A rotary tool for cutting woody brush, that includes an engine, a transmission for transferring rotational movement to a head, an elongate pole, and the head is positioned at the end of the pole, and connected to the head is a cutting blade that has a flat middle section that is adapted to engage and opposite cutting sections that extend downwardly from the middle section, and the cutting sections have cutting surfaces and, in embodiments, the tool includes cutting line.

Description:
[0001]    The applicant claims the benefit of U.S. Application No. 62,000,882 that was filed on May 20, 2014. The present invention relates to an improvement for a rotary line trimmer. Trimmers that use line, such as nylon line or other heavy gauges thermoplastic material are attached to a rapidly spinning head and are used to trim grass, weeds and other non-woody materials. In some embodiment rather than using line, a resin blade or even a metal chain is attached to the rotating head of the trimmer. The motor is typically provided on the opposite end of a pole and may be powered by a small gas engine or an electric motor. The control of motor is provided by a switch that is accessible to the user. 
     
    
       [0002]    While the prior art embodiments satisfactory will cut grass, they are generally not effective nor are they designed for cutting heavy brush or small saplings that have woody stems. The plant cell wall surrounds the cell membrane. It is made up of multiple layers of cellulose which are arranged into primary and secondary walls. The cellulose content of cotton is 90% and wood is 50% cellulose. The cell walls of all vascular plants also contain a polymer called lignin. Lignin is water-resistant. It reinforces cell walls, keeping them from collapsing. This is particularly important in the xylem, because the column of water in the hollow xylem cells is under tension (negative pressure) and without the lignin reinforcement the cells would collapse. Lignin provides the mechanical support for stems and leaves and supplies the strength and rigidity of plant walls. 
         [0003]    The present invention is therefore directed to an improvement for conventional rotary line trimmers by providing a blade that will allow the tool to cut woody plants or saplings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a top view of the blade according to an embodiment of the invention. 
           [0005]      FIG. 2  is a view in elevation of the blade according to the embodiment of the invention depicted in  FIG. 1  that includes a view of the top surface. 
           [0006]      FIG. 3  is a view in elevation of the blade according to the embodiment of the invention depicted in  FIG. 1  that includes a view of the bottom surface of the blade. 
           [0007]      FIG. 4   a  is an end view of the blade in elevation. 
           [0008]      FIG. 4   b  is an end view of the opposite end of the blade depicted in  FIG. 1 . 
           [0009]      FIG. 5  is a side view in elevation of the blade of  FIG. 1 . 
           [0010]      FIG. 6  is a side view in elevation taken from the opposite side from that of  FIG. 5 . 
           [0011]      FIG. 7  depicts the blade assembled on the head of a rotary trimmer. 
           [0012]      FIG. 8  is an exploded view of a head assembly including the blade of  FIGS. 1-6  and cartridge in elevation. 
           [0013]      FIG. 9  is an exploded view of a head assembly including the blade of  FIGS. 1-6  and cartridge in perspective. 
           [0014]      FIG. 10  is a perspective exploded view of a head assembly including a blade and clutch elements in perspective 
           [0015]      FIG. 11  is a front perspective view of a further embodiment of a blade. 
           [0016]      FIG. 12  is a rear perspective view of the embodiment of  FIG. 11 . 
           [0017]      FIG. 13  is a side view in elevation of the blade of  FIG. 11 . 
           [0018]      FIG. 14  is an opposite side view in elevation of the blade of  FIG. 11 . 
           [0019]      FIG. 15  is a bottom view of a clutch plate assembly used in an embodiment of the invention. 
           [0020]      FIG. 16  is a top view of the clutch plate of  FIG. 15 . 
           [0021]      FIG. 17  is a front view in elevation of the clutch plate of  FIG. 15 . 
           [0022]      FIG. 18  is end view in elevation of the clutch plate of  FIG. 15 . 
           [0023]      FIG. 19  is rear view in elevation of the clutch plate of  FIG. 15 . 
           [0024]      FIG. 20  is an opposite end view in elevation of the clutch plate of  FIG. 18 . 
           [0025]      FIG. 21  is a further embodiment of a clutch plate in engagement with a blade and the head member of a rotating tool. 
           [0026]      FIG. 22  is a front view in elevation of the clutch member depicted in  FIG. 21 . 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Now referring to  FIG. 1 , an embodiment of a blade  101  according to the present invention is shown which is designed to be attached to a conventional rotary trimmer. These trimmers have a rapidly rotating head that is provided on the end of a pole. A control switch and motor are provide on the opposite end. In the embodiment depicted in  FIG. 1  the blade  101  includes an engagement region or leading edge  103  on a first lateral side that includes a serrated edge. The lateral ends also include a serrated surface as well as a transitional region  105  that is angled to the end surface  107 . Surface  107  also includes a series of teeth designed to engage woody plants. The opposite side of the blade also has a leading edge  113 , a transitional region  111  and an end edge  111 . 
         [0028]    As best seen in  FIG. 2  the blade has a center region  117  from which two opposite lateral extension parts  115  and  119  are angled downwardly. In a preferred embodiment the blade is comprised of steel. While the embodiment depicted in the  FIGS. 1-7  includes a blade that defines three separate and distinct planes it is completed that the blade may take other shapes such as a polygonal blade like that disclosed in  FIG. 1  wherein the blade curves away on opposite sides from the central region. In yet further contemplated arrangement the blade may take the form of cross wherein four opposite blade extension are provide at 90 degree locations. In yet a further embodiment the blade may take the form of a conical section shape, or in the shape of a bell, wherein there is a flat center section for engagement to the head or line cartridge of the trimmer. The outer flared section of the bell or conical section can be provided with a continuous serrated edge or other saw teeth arrangements. The edge of the flared section of the bell may define a single plane or may have portions that do not extend to the planar location. 
         [0029]      FIG. 3  depicts the rear surface of the blade. It includes a hook and look fastener elements  125  and  126  that have been affixed to the blade surface.  FIG. 4   a  depicts and end view of the blade and includes a depiction of cutting teeth  11  on the end of the surface.  FIG. 4   b  depicts the opposite end.  FIGS. 5 and 6  depicts side views of the blade, both front and rear. 
         [0030]    Now referring to  FIG. 7 , blade  202  according to an embodiment of the invention, is depicted in engagement with the head of a rotary trimmer. The blade  202  is positioned and attached to provide for rotational movement between element  714  and the cartridge  706 . The head is posited on the end of pole  719 . A guard  750  is also attached to the end of pole  719 . Line  705  extends from cartridge  706  which can be spooled out as new line may be needed. As seen in  FIG. 8 , the rotational movement of the blade and cartridge is effected by axel  785  which extends through a central aperture on the blade and into the top of the cartridge  706 . 
         [0031]    As best seen in  FIG. 9 , the top of cartridge  706  is provided with hook and loop element such as strip  925  that is positioned to engage opposite strips on the rear surface of blade  202 . The presence of these strips allows the blade to rotate with the cartridge. However, if the blade impacts a stationary object and sufficient force is translated through the blade, the engaged strips can be displaced and the axel  785  is able to turn independent from the blade. 
         [0032]    While a hook and loop fastener is depicted in the embodiment shown, it is contemplated that other releasable fasteners can be advantageously used such as break away pins that engage both the blade and the cartridge or releasable adhesive. 
         [0033]      FIG. 10  depicts a further embodiment wherein the assembly further includes a clutch plate  1104  and blade  2100  that is positioned between the head  1108  and the drive  1107  elements of a rotary tool. The head includes a portal  1125  from which cutting line  1161  extends. In this embodiment  2100  the blade has a ridges  2101  and  2102  that extend from the bottom surface  2107  of the blade. In this embodiment the clutch plate  1104  is attached to head  1108  by double sided adhesive tape  1110  and  1118 . While adhesive tape is used in this embodiment depicted in  FIG. 10 , other forms of adhesives may be advantageously used to attach the clutch plate to the head  1108  including hook and loop device and fasteners. The clutch plate engaged the bottom surface of the blade by frictional engagement and can be displaced when a heavy loads is encountered by the blade such as a large woody plant, fence or rock. As best seen in  FIG. 13 , an opposite groove  3102  and  3101  extends into the top surface as the ridge and groove structure is formed by press fitting the metal blade  2100 . This groove and ridge feature provides improved strength of the blade and increases the coefficient of friction between clutch plate  1104  and blade  2100  along the interface of the bottom surface  2107 . 
         [0034]    In this embodiment of  FIG. 10  that includes both a blade and string cutting implements, preferable the blade is oriented at a position approximately ninety degrees to the location where the string exits the head. In the event that the blade is not optimally positioned, it can interfere and cut the string. 
         [0035]    Referring no to  FIG. 1 , the opposite end of the blade extend from the middle section to define and angel that is 115 degrees. However angle anywhere from 110 degrees to 140 degrees may be useful depending on the application. As the angle approaches of the cutting section to the middle section approaches 180 degrees, the tool is harder to control and can become more dangerous to use. In preferred embodiments, the opposite cutting portions of the blade form angles between 115 to 120 degrees with the middle section. In an embodiment both the blade and the clutch member will flex in response to pressure exerted on the blade. 
         [0036]    Referring to  FIGS. 15-20 , a clutch member  3101  as a length that is slightly less than the middle section of the blade for which it is used. It has a central aperture  1305  allow the drive member  1352  to pass through the member. The member  3103  is affixed to the clutch and is used for attachment to the head. Fig,  21  depicts an alternative arrangement  4201  that includes a clutch member  3202 . This member has a profile with a middle section  3214  that not in the same plane as the outer section  3216  and  3218 . Section  3216  and  3218  engage the blade member. This embodiment provides some flexibility between the clutch and blade  4250 . As head  3280  is attached to the opposite member  3281  on the tool the clutch  3202  is comprised and put into tension and therefore will flex to provide an improved grip on the blade.