Abstract:
A three-in-one cutting head for a rotary trimmer usable with discrete lengths of string, flail blades, and fan blades is provided. The present disclosure represents an improvement over presently existing multi-purpose trimmer heads in that there is no requirement for the trimmer head to be disassembled in order to change the different blades or strings. The cutting head being selectively rotationally driven through a drive shaft includes a generally cylindrical body having first and second pairs of diametrically opposed apertures disposed on a periphery of the body; at least one clamping member disposed in the body adjacent to each aperture of the first diametrically opposed pair configured for releasably retaining at least one cutting string; and at least one holding member disposed in the body adjacent to each aperture of the second diametrically opposed pair configured for releasably retaining at least one blade.

Description:
PRIORITY 
     This application claims priority to an application entitled “THREE-IN-ONE TRIMMER HEAD” filed in the United States Patent and Trademark Office on Jul. 12, 2006 and assigned Ser. No. 60/830,372, the contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to cutting heads for rotary trimmers and, more specifically, to a three-in-one rotary trimmer head usable with discrete lengths of string, flail blades, and fan blades. The present disclosure represents an improvement over presently existing multi-purpose trimmer heads in that there is no requirement for the trimmer head to be disassembled in order to change the different blades or strings. 
     2. Description of the Related Art 
     Applicant is the inventor of U.S. Pat. Nos. 5,758,424 and 5,896,666, the disclosures of which are incorporated in their entirety by reference in this application. Applicant&#39;s inventions of U.S. Pat. Nos. 5,758,424 and 5,896,666 are directed to a cutting head for a string trimmer which accommodates any string gauge thickness and which may be easily and quickly re-threaded upon failure of the string previously disposed therein. Clamping members are provided to clamp the strings within the cutter head, with the clamping force being provided by springs and augmented by centrifugally generated moments. The clamping members are capable of generating two degrees of clamping force. The lesser degree of clamping force can be overcome by a string forceably inserted into the cutting head. 
     The cutting heads of applicant&#39;s U.S. Pat. Nos. 5,758,424 and 5,896,666 operate in an efficient and smooth manner, however, they are only capable of accommodating discrete strings. 
     There is a need for a cutting head which can accommodate different types of cutting members, such as flail blades, discrete strings, and fan blades. Fan blades are used for purposes of generating a blowing force for removing debris from sidewalks or walkways. Flail blades are used for cutting thick vegetation, as well as tall vegetation. String cutters are used to cut low vegetation, for edging vegetation areas, and for cutting vegetation near walls or other hard structures. There is also a need for a universal type trimmer head which can be rapidly and easily converted from one type of cutting means or fan blade means into a different structure depending on the work to be accomplished at that time. 
     There are in existence various trimmer heads which can accommodate different types of blades, such as a flail blade and a fan blade, however, those devices are cumbersome and require disassembly of the head in order to change from one type of blade to another type of blade. Hence, they are difficult to operate and time consuming in changing from one embodiment to a different embodiment. 
     The present disclosure overcomes the shortcomings of the prior art and provides a trimmer head which is capable of easily and quickly being converted from one type of blade structure to a different type of blade structure, without requiring disassembly of the head. 
     SUMMARY 
     A three-in-one cutting head for a rotary trimmer usable with discrete lengths of string, flail blades, and fan blades is provided. The present disclosure represents an improvement over presently existing multi-purpose trimmer heads in that there is no requirement for the trimmer head to be disassembled in order to change the different blades or strings. 
     According to one aspect of the present disclosure, a cutting head for a rotary trimmer, the cutting head being selectively rotationally driven through a drive shaft is provided. The cutting head includes a generally cylindrical body having first and second pairs of diametrically opposed apertures disposed on a periphery of the body; at least one clamping member disposed in the body adjacent to each aperture of the first diametrically opposed pair configured for releasably retaining at least one cutting string; and at least one holding member disposed in the body adjacent to each aperture of the second diametrically opposed pair configured for releasably retaining at least one blade. The at least one blade is a flail blade or a fan blade. 
     In another aspect, the at least one holding member includes a post for rotatably engaging the at least one blade, wherein the at least one blade includes a U-shaped clamping portion configured to engage the post. 
     In a further aspect, a sleeve disposed on the post configured to facilitate rotation of the at least one blade, wherein the U-shaped clamping portion engages the sleeve in a snap fit. 
     In another aspect, the first and second pairs of diametrically opposed apertures are equally spaced along the periphery of the body. 
     According to a further aspect of the present disclosure, the at least one clamping member is a cam configured to contact a pressing wall. The cam is biased to contact the pressing wall by a spring. 
     In yet another aspect, each of the at least one clamping member is disposed in a clamp housing, the clamp housing being rotatable about an axis extending generally perpendicular to the body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view of the three-in-one trimmer head of the present disclosure which includes both flail blades and discrete strings; 
         FIG. 2A  is a perspective view of the three-in-one trimmer head of the present disclosure in the embodiment where only flail blades are attached to the trimmer head; 
         FIG. 2B  is a perspective view of the three-in-one trimmer head of the present disclosure in the embodiment where only discrete strings are attached to the trimmer head; 
         FIG. 2C  is a perspective view of the three-in-one trimmer head of the present disclosure in the embodiment where only fan blades are attached to the trimmer head; 
         FIG. 3  is an exploded perspective view of the trimmer head of the present disclosure illustrating a flail blade, a discrete string, and a fan blade; 
         FIG. 4  is a partial view of a string clamped by a clamping member according to an embodiment of the present disclosure; 
         FIG. 5  is a partial view of a string clamped by a clamping member according to another embodiment of the present disclosure; 
         FIG. 6  is a partial view of a string clamped by a clamping member according to a further embodiment of the present disclosure; 
         FIG. 7  is a partial view of a string clamped by a clamping member according to yet another embodiment of the present disclosure; and 
         FIG. 8  is a perspective view of a rotatable clamp housing in accordance with an aspect of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments of the present disclosure will be described hereinbelow with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. 
     Turning to  FIG. 1 , the three-in-one trimmer head of the present disclosure is generally designated by the numeral  10  and includes a body portion  12  to which is releasably connected discrete strings  14  and flail blades  16 . The discrete strings  14  are connected to the body  12  by a clamping member of the type as disclosed in applicant&#39;s U.S. Pat. Nos. 5,758,424 and 5,896,666. The flail blades  16  are releasably connected to the body portion  12  by means of a snap fitting connection, as described in detail below. 
     Usually, the three-in-one trimmer head  10  is used in an embodiment which only includes the flail blades  16  for cutting high or thick vegetation. Each flail blade  16  is preferably made of a plastic material, although it may be made of metal, and is of sturdy construction so as to easily cut the thick vegetation. As shown in  FIG. 1 , the flail blades  16  include teeth  18  which aid in the cutting of high vegetation. 
     The embodiment in which the flail blades  16  only are used is illustrated in  FIG. 2A . Because of the sturdiness of the flail blades  16 , the configuration as shown in  FIG. 2A  is not used when trimming is to take place close to wall structures wherein a flail blade  16  may contact the wall and break, thereby possibly causing injury to the operator. 
     When it is desired to trim vegetation along an edge or near a wall or similar structure, the flail blades  16  will be disconnected from the body  12 , and discrete strings  14  will be inserted into the trimmer head  10  by a clamping mechanism of the type disclosed in applicant&#39;s U.S. patents as identified above. The embodiment in which the discrete strings  14  only are used is illustrated in  FIG. 2B . 
     Furthermore, after the vegetation has been cut, the discrete strings  14  will be disconnected from the body  12  and fan blades  26  may be coupled to the body, as shown in  FIG. 2C , to blow the cut vegetation to an area for easy pickup. 
     Referring to  FIG. 3 , the generally cylindrical body portion  12  includes an upper part or cover  20  and a lower portion or disc-shaped base plate  22 . The base plate  22  is preferably formed with a circular shape. Alternatively, the base plate  22  can be formed with any shape that allows the base plate  22  to rotate about its center in a balanced state. For example, the base plate  22  can be formed as a rectangle or a star with equally-spaced points. It is to be appreciated that the upper part or cover  20  will be formed with the corresponding shape. Also, the cutting head  10  can be formed to various sizes by cutting the cover  20  and base plate  22  to the desired dimensions. 
     The disc-shaped base plate  22  is formed with a central hub  38 . The hub  38  is frustoconically shaped and extends from the base plate  22  in a single direction. A drive shaft aperture  40  is formed in the hub  38  and dimensioned to allow a drive shaft to pass therethrough. The cover  20  includes a corresponding hub  42  and drive shaft aperture  44 . When the body  12  is assembled, the drive shaft may be secured to the body  12  by any conventional coupling or coupling means via apertures  40  and  44 . 
     The generally cylindrical body  12  includes a first pair of diametrically opposed apertures  46  disposed on a periphery of the body and a second pair of diametrically opposed apertures  48  disposed on the periphery. It is to be appreciated that the first and second pairs are located on the periphery of the body so the body will rotate about its center in a balanced state. A clamping member  50  is disposed in the body adjacent to each aperture of the first diametrically opposed pair  46  configured for retaining a cutting string  14 , the details of which will be described below. A holding member  52  is disposed in the body adjacent to each aperture of the second diametrically opposed pair  48  configured for retaining at least one blade. As will be described below, the blade may be a flail blade or a fan blade. 
     With reference to  FIG. 3 , the holding member  52  will be described. The lower portion  22  of the body  12  includes posts  24  projecting from the lower portion  22  for rotatably engaging either a flail blade  16  or a fan blade  26 . Disposed about each post  24  is a steel sleeve  28  which facilitates rotational movement of either the flail blade  16  or the fan blade  26 . 
     As shown in  FIG. 3 , each flail blade  16  includes a clamping portion  30  of generally U-shaped configuration having a restricted entranceway  32  to enable the flail blade  16  to be snapped about a steel sleeve  28 . Similarly, each fan blade  26  includes a U-shaped clamping portion  34  having a restricted entranceway  36  for enabling the fan blade  26  to be snapped onto a steel sleeve  28 . The body  12  is designed such that either flail blades  16  or fan blades  26  may be snapped into place within the body, without requiring disassembly of the upper portion  20  of the body  12  from the lower portion  22 . 
     The clamping mechanism which is employed for attaching the discrete strings  14  to the body  12  are designated by the numeral  50 . Exemplary clamping members are shown and described in U.S. Pat. Nos. 5,758,24 and 5,896,666, the contents of which are incorporated by reference. FIGS. 3-6 of U.S. Pat. Nos. 5,758,24 and 5,896,666 are reproduce here as  FIGS. 4-7  for clarity. Referring to  FIG. 4 , cam  136  is pivotally mounted to post  138  which extend from the base plate  22 . The cam  136  is mounted so that the top surface of the cam is below the height of a pressing walls  132  formed in the base plate  22 . Spring  140  is provided to bias the cam  136 . The cam  136  is formed and mounted onto the posts  138  so that the center of gravity of the cam  136  is located at a point between the corresponding post  138  and the pressing wall  132 , as shown in  FIG. 4  with the center of gravity indicated by “C. G.”. The spring  140  is secured to the cam  136  such that the cam  136  are urged in a clockwise direction into contact with the pressing wall  132 . The spring  140  creates the lesser degree of clamping force which is capable of maintaining the string  14  between the cam  136  in the pressing wall  132 . The spring force of the spring  140  is selected to allow counter-clockwise rotation of the cam  136  with the insertion of the strings  14  into the cutting head  10  from a location outside the body  12 . The rotation of the cutting head  10  during use, in either a clockwise or counter-clockwise direction, creates a centrifugal force which acts on the centers of gravity of the cam  136  and creates torque about the post  138  which cause the cam  136  to come into tighter engagement with the strings  14 . Also, the centrifugal force radially extends the strings  14  and causes a thinning effect with the cross-section of the strings  14  being slightly reduced, thereby allowing the spring  140  and the torque acting on the cam  136  to urge the cam  136  into closer engagement with the pressing wall  132  and create an even tighter engagement of the cam  136  and the pressing wall  132  about the strings  14 . 
     In another embodiment of clamping members  50 , torsional springs  144  may be employed about the post  138  as shown in  FIG. 5  in place of the coil spring  140 . One end  146  of the torsional spring  144  is secured to base plate  22  with the other end  148  being secured to the cam  136  as shown in the cut-away section of  FIG. 5 . The end  148  urges the cam  136  in a clockwise direction about the post  138 . 
     Alternatively, the cam  136  can be substituted for a different-shaped clamping member. As shown in  FIG. 6 , a cylindrical rod  150  may be pivotally mounted to the post  138  with its center of gravity located between the post  138  and the pressing wall  132 . Any shaped clamping member may be used with the present disclosure so long as it is formed with its center of gravity disposed between the post  138  and the pressing wall  132  and comprises an edge or face which can cooperate with the pressing wall  132  to clamp the string  14 . 
     In a further embodiment of the clamping members, the cutting head  10  may be formed with the cam  136  capable of frictionally engaging the strings  14  without the use of the spring  140 . As shown in  FIG. 7 , the post  138  may extend through the base plate  22 , or through the cover  20 , not shown. A handle  152  is provided at the end of the post  138  opposite the cam  136 . The cam  136  may be manually rotated about the post  138  by rotating the handle  152 . The cam  136  forms an opening with the pressing wall having a width “D” which may be varied. The width “D” is measured between the closest points of the cam  136  and the pressing wall  132  and represents the narrowest cross-section of the opening. The string  14  is formed with a diameter “d”. To dispose the string  14  within the cutting head  10 , the cam  136  is rotated so that the width “D” of the opening is greater than the diameter “d” of the string  14 . Once within the cutting head  10 , the cam  136  is rotated to frictionally engage the string  14  and press the string  14  against the pressing wall  132 , with the width “D” being less than the diameter “d” of the string  14 . A plurality of spaced ribs  154  may be provided to enhance the frictional engagement of the cam  136  with the string  14 . In use, the centrifugal force created by the rotation of the cutting head  10  acts on the center of gravity of the cam  136 , indicated by “C. G.”, to enhance the gripping engagement of the string  14 . The rotation of the cutting head  10  causes the cam  136  to create a moment about the post  138  and clamp string  14  in tighter engagement. 
     In a further embodiment, each clamping member  50  is mounted within a rotatable clamp housing  54  within the body  12 , such that, as a string  14  encounters a solid object, the clamping member  50  and its associated housing  54  are rotated about a generally vertical axis so as to obviate or minimize the development of a stress concentration in the string in the vicinity at which it is engaged by the clamp housing, as described in commonly owned U.S. patent application Ser. No. 11/086,082 filed, the contents of which are incorporated by reference. Each rotatable clamp housing  54  is rotatable about an axis, designated “a” in  FIG. 2B , extending perpendicular to or generally vertical to the cover  20  and base plate  22 . Referring to  FIG. 8 , the rotatable housing  54  includes a generally cylindrically shaped housing  56 , the lower end of which includes a circular support portion  58  of smaller diameter than the cylindrically shaped housing  56 . Extending from the upper end of the cylindrically shaped housing  56  is a curved tang  60  which provides a stop for limiting the amount of angular rotation of the rotatable clamp housing  54  about the axis “a” within the cutter head  10 . Each rotatable clamp housing  54  is mounted within the cutting head  10  with the circular support portion  58  being rotatably supported within a circular opening provided in the base plate  22 . The curved tang  60  of each rotatable clamp housing  54  is accommodated in a curved recess within the upper cover  20 , with the curved recess extending about 180 degrees, thus enabling the rotatable clamp housing  54  to be rotated 90 degrees about axis “a” in either direction (as indicated by arrows “b”) from the neutral position as shown in  FIG. 2B . The rotatable clamp housing  54  further includes an aperture  62  for receiving the string  14  and guiding the string to the clamping member disposed in the housing  54 . 
     Usually, when high vegetation has to be cut, the configuration of the three-in-one trimmer head  10  is as illustrated in  FIG. 2A , with the flail blades  16  being connected to the body  12 . The cutter head  10  is rotationally driven by a motor, not shown, through a drive shaft which spins the trimmer head  10  at a velocity sufficient to cut through the thick vegetation. 
     In order for the trimmer head to be used adjacent walls or for cutting edges of a vegetation area, the flail blades are easily and quickly disconnected from the body  12  and discrete strings  14  are connected to the body  12 , as shown in  FIG. 2B . 
     For purposes of blowing debris or cuttings away from walkways and sidewalks, next, the strings  14  would be removed from the head  10 , and two fan blades  26 , diametrically opposed, would be snapped onto the trimmer head, as shown in  FIG. 2C . At that time, upon rotation of the trimmer head, sufficient blowing air would be generated by the fan blades for blowing debris from walkways, etc. 
     For certain applications, the operator may have both the flail blades  16  and the discrete strings  14  connected to the trimmer head  10 , as shown in  FIG. 1 . 
     Thus, there has been shown and described an improved three-in-one trimmer head which does not require disassembly in order to accommodate flail blades, fan blades, and discrete nylon strings. The configuration of the subject three-in-one trimmer head may be quickly and rapidly changed, merely by snapping in either the flail blades or the fan blades, or by inserting discrete strings into the clamping mechanism of the present disclosure. There is no need to remove the cover  20  of the body  12  in order to change the configuration of the trimmer head. Many changes, modifications, variations and other uses and applications of the present disclosure will, however, become apparent to those skilled in the art after considering the foregoing specification taken together with the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the disclosure are deemed to be covered by the present disclosure.