STRING TRIMMER HEAD WITH CURVED TRIMMER LINE GUIDE

Abstract

A trimmer head assembly for a trimming machine. The trimmer head assembly includes a spool. The spool has a central tubular hub. The spool also has a central flange that radially extends from the hub. A trim line conduit is joined to the central flange. The trim line conduit has a first open end. The first open end leads to a first straight section. The first straight section leads to a curved central section. The curved central section leads to a second straight section. The second straight section leads to a second open end. The curved central section passes around the center of the spool. A housing is provided that receives the spool therein. When loading trimmer line into the trimmer head assembly, the shaped of the conduit enables the trimmer line to pass around the central opening in the spool without binding.

Claims

1. A spool for a trimmer head of a vegetation trimmer machine comprising: a cylindrical core; a first horizontal flange extending radially outwardly from a wall of the cylindrical core; a second horizontal flange extending radially outwardly from the wall of the cylindrical core; and a storage space for trimmer line defined between the first horizontal flange and the second horizontal flange; an unobstructed trimmer line guide channel integrally formed in the first horizontal flange, wherein the trimmer line guide channel extends from a first side of the spool to a generally opposing second side of the spool and is of a substantially constant diameter; wherein the trimmer line guide channel is coplanar with the first horizontal flange and has a first opening and a second opening that are adapted for direct alignment to eyelet openings in a housing of the trimmer head; wherein the first and second openings of the trimmer line guide channel form a funnel or are flare-shaped and include a side relief opening adapted to direct the trimmer line toward the cylindrical core wall and into the storage space.

2. The spool of claim 1 further comprising: a third horizontal flange extending radially outwardly from a wall of the cylindrical core.

3. The spool of claim 2 further comprising: a second storage space for trimmer line defined between the first horizontal flange and the third horizontal flange.

4. The spool of claim 3 wherein the first and second openings of the trimmer line guide channel are adapted to direct the trimmer line toward the cylindrical core wall and into the first storage space and into the second storage space.

5. The spool of claim 1 wherein the trimmer line guide channel further comprises: a first straight section extending between the first opening and a curved central section; and a second straight section extending between the curved central section and the second opening.

6. The spool of claim 5 wherein the trimmer guide line channel further comprises: a second curved central section between the first and second straight sections.

7. The spool of claim 1 wherein the trimmer line guide channel further comprises: a first straight section extending between the first opening and a central relief section; a second straight section extending between the central relief section and the second opening; a first deflector having a first offset salient point disposed within the central relief section; and a second deflector having a second offset salient point disposed within the central relief section.

8. The spool of claim 7 wherein the first deflector and first offset salient point is oriented towards the first straight section; and wherein the second deflector and second offset salient point is oriented towards the second straight section.

9. The spool of claim 7 wherein the first deflector and first offset salient point are angled to deflect trimmer line to the right as trimmer line is inserted through the first straight section via the first opening; and wherein the second deflector and second offset salient point are angled to deflect trimmer line to the right as trimmer line is inserted through the second straight section via the second opening.

10. A spool for a trimmer head of a vegetation trimmer machine comprising: a cylindrical core; a first horizontal flange extending radially outwardly from a wall of the cylindrical core; a second horizontal flange extending radially outwardly from the wall of the cylindrical core; and a storage space for trimmer line defined between the first horizontal flange and the second horizontal flange; an unobstructed trimmer line guide channel integrally formed in the second horizontal flange and the wall of the cylindrical core, wherein the trimmer line guide channel extends from a first side of the spool to a generally opposing second side of the spool and is of a substantially constant diameter; wherein the trimmer line guide channel is coplanar with the second horizontal flange and has a first opening and a second opening that are adapted for direct alignment to eyelet openings in a housing of the trimmer head; wherein the first and second openings of the trimmer line guide channel form a funnel or are flare-shaped and include a side relief opening adapted to direct the trimmer line toward the cylindrical core wall and into the storage space.

11. The spool of claim 10 further comprising: a third horizontal flange extending radially outwardly from a wall of the cylindrical core.

12. The spool of claim 11 further comprising: a second storage space for trimmer line defined between the first horizontal flange and the third horizontal flange.

13. The spool of claim 12 wherein the first and second openings of the trimmer line guide channel are adapted to direct the trimmer line toward the cylindrical core wall and into the first storage space and into the second storage space.

14. The spool of claim 10 wherein the trimmer line guide channel further comprises: a first straight section extending between the first opening and a curved central section; and a second straight section extending between the curved central section and the second opening.

15. The spool of claim 14 wherein the trimmer guide line channel further comprises: a second curved central section between the first and second straight sections.

16. The spool of claim 10 wherein the trimmer line guide channel further comprises: a first straight section extending between the first opening and a central relief section; a second straight section extending between the central relief section and the second opening; a first deflector having a first offset salient point disposed within the central relief section; and a second deflector having a second offset salient point disposed within the central relief section.

17. The spool of claim 16 wherein the first deflector and first offset salient point is oriented towards the first straight section; and wherein the second deflector and second offset salient point is oriented towards the second straight section.

18. The spool of claim 16 wherein the first deflector and first offset salient point are angled to deflect trimmer line to the right as trimmer line is inserted through the first straight section via the first opening; and wherein the second deflector and second offset salient point are angled to deflect trimmer line to the right as trimmer line is inserted through the second straight section via the second opening.

19. A method of loading trimmer line onto a trimmer head comprising: aligning a first guide opening of a spool with a first eyelet opening in a housing of the trimmer head, the spool further comprising: a cylindrical core; a first horizontal flange extending radially outwardly from a wall of the cylindrical core; a second horizontal flange extending radially outwardly from the wall of the cylindrical core; a storage space for trimmer line defined between the first horizontal flange and the second horizontal flange; an unobstructed trimmer line guide channel integrally formed in one of the first horizontal flange or the second horizontal flange, wherein the trimmer line guide channel extends from a first side of the spool to a generally opposing second side of the spool and is of a substantially constant diameter; and wherein the trimmer line guide channel is coplanar with the horizontal flange in which its formed and has the first guide opening at the first side of the spool and a second guide opening at the second side of the spool; aligning the second guide opening of a spool with a second eyelet opening in the housing of the trimmer head; inserting an end of a single length of trimmer line into the first eyelet opening of the housing; advancing the single length of trimmer line into the first guide opening of the spool, through the line guide channel and, bypassing the central second opening, through the second guide opening; and out of the second eyelet opening of the housing; and winding the trimmer line around the wall of the cylindrical core and into the storage space.

20. The method of claim 19 wherein the first guide opening and second guide opening of the trimmer line guide channel form a funnel or are flare-shaped and include a side relief opening adapted to direct the trimmer line toward the wall of the cylindrical core and into the storage space.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0026] A sample embodiment of the disclosure is set forth in the following description, is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. The accompanying drawings, which are fully incorporated herein and constitute a part of the specification, illustrate various examples, methods, and other example embodiments of various aspects of the disclosure. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. One of ordinary skill in the art will appreciate that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements may not be drawn to scale.

[0027] For a better understanding of the present invention, reference is made to the following description of an exemplary embodiment thereof, considered in conjunction with the accompanying drawings, in which:

[0028] FIG. 1 is cross section view of the fully assembled trimmer head invention attached to a trimmer machine drive shaft which passes vertically through the center of the spool;

[0029] FIG. 2 is an exterior isometric view of the fully assembled trimmer head invention;

[0030] FIG. 3 is a top isometric view of the bottom cap and the knob assembled as shown in trimmer head FIGS. 1-2;

[0031] FIG. 4 is a top isometric view of the bottom cap as shown in trimmer head of FIGS. 1-2;

[0032] FIG. 5 is an exploded view all trimmer head parts as shown in trimmer head FIGS. 1-2;

[0033] FIG. 6 is an isometric view of spool S and the bottom cap assembled as shown in FIG. 1;

[0034] FIG. 7 is an isometric view of spool S not assembled to the knob as shown in FIG. 6;

[0035] FIG. 8 is a top isometric view of the knob as shown in trimmer head FIGS. 1-2;

[0036] FIG. 9 is a top isometric view of 2S spool guide channel cover plate;

[0037] FIG. 10 is a bottom isometric view of the cover plate;

[0038] FIG. 11 is a drawings of spool S and the knob assembled and not assembled, drawings Illustrate how to convert the same spool so that the trimmer head can be used on a trimmer machine that has a drive shaft that turns in a clockwise and or counter-clockwise direction;

[0039] FIG. 12 is a drawing of trimmer head invention attached to a straight shaft, trimmer machine, which typically rotates counter-clockwise and has a vertical drive shaft that passes through the center of the spool;

[0040] FIG. 13 is a drawing of trimmer head invention attached to a curved shaft, trimmer machine, which typically rotates clockwise and has a vertical drive shaft that passes through the center of the spool;

[0041] FIG. 14 is a top isometric view of the spool showing the placement of repositionable stop that prevents misplacement and assembly of the knob to the spool once the direction of the trimmer machine drive shaft has been determined;

[0042] FIG. 15 is a top isometric view of reposition able stop with snap fitting as shown assembled to the spool in FIG. 14;

[0043] FIG. 16 is a top isometric view of spool guide channel cover plate;

[0044] FIG. 17 is a top isometric view of the spool showing a non-linear trimmer line U-shaped guide channel;

[0045] FIG. 18 is a top isometric view of the spool assembled with the spool cover plate;

[0046] FIG. 19 is a top view of main trimmer head housing body;

[0047] FIG. 20 is a side isometric view of the main trimmer head housing body shown with metal eyelets and the extended special extension of the main housing capturing the long center drive shaft to secure the main housing body firmly to the machine's drive shaft arbor;

[0048] FIG. 21 is a bottom view of main trimmer head housing body;

[0049] FIG. 22 is a top view of the spool which illustrates on which side of the spool to insert placement of insert stop for a trimmer machine that turns counterclockwise;

[0050] FIG. 23 is a top view of the spool illustrating that placement of insert stop can be placed on the opposite side of the spool at peg receiver openings on either end;

[0051] FIG. 24 is a top isometric view of turn bump knob showing extending key to mate and interlock with the spool;

[0052] FIG. 25 is a side isometric view of turn bump knob that illustrates close up view of the finger grips used for reloading and winding the inner spool;

[0053] FIG. 26 is a top cross section view of the bottom cap, the spool, the eyelets, the main housing body, showing clearly the linear and non-linear path the trimmer line travels via the guide channel from insertion of the line through a eyelet and exiting the eyelet on the opposite end of the trimmer head;

[0054] FIG. 27 is a top isometric view of the spool;

[0055] FIG. 28 is a perspective view of a second exemplary embodiment of a trimmer head assembly;

[0056] FIG. 29 is an exploded view of the embodiment of FIG. 28;

[0057] FIG. 30 is a cross-sectional view of the second exemplary embodiment of FIG. 28, viewed along section line 30-30;

[0058] FIG. 31 is a cross-sectional view of a third embodiment of the present invention trimmer head assembly;

[0059] FIG. 32 is a cross-sectional view of a fourth embodiment of the present invention trimmer head assembly; and

[0060] FIGS. 33a and 33b show a segment of trimmer line being advanced through the exemplary embodiment of FIG. 32.

[0061] Similar numbers refer to similar parts throughout the drawings.

DETAILED DESCRIPTION

[0062] Although the present invention trimmer head can be embodied in many ways, only three exemplary embodiments are illustrated. These embodiments are selected in order to set forth three of the best modes contemplated for the invention. The illustrated embodiments, however, are merely exemplary and should not be considered a limitation when interpreting the scope of the appended claims.

[0063] Together, body members 7 and 11 are referred to herein as the trimmer cutting head housing. A threaded fastener (bolt or nut) 6 is used to attach the main housing body 7 to drive shaft 3. In order to secure body member 7 to the trimmer machine apparatus, a threaded fastener (bolt or nut) 6 is inserted through a central opening 14 of an extended housing to accommodate a drive shaft that extends through and beyond the center of a spool. As used herein, spatial terms such as top, bottom, upper, lower, etc. refer to the relative positions that the various structural components described herein would assume when trimmer cutting head 1 is in use, i.e., when attached to the rotating drive shaft of a conventional internal combustion or electric powered grass/weed trimmer machine.

[0064] Referring to FIG. 1 there is shown an assembled cross section view of a first presently preferred embodiment of a trimmer cutting head 1 according to the invention that is used for cutting vegetation in conjunction with an internal combustion engine or electric motor powered trimmer apparatus commonly known as handheld grass/weed trimmer or brush cutting machine. Trimmer head 1 preferably comprises a rigid molded plastic first or top body member 7 and a rigid molded plastic second or bottom body member 11. Together, body members 7 and 11 are referred to herein as the trimmer head housing. Body members 7 and 11 may be releasably fastened to one another by a snap, threaded, Jslot or other releasable connection. For example, suitable fastening means may include generally stiff yet resilient tabs 22 (FIGS. 2, 3, 4) upwardly projecting from the body member 11.

[0065] Tabs 22 are adapted to pass through correspondingly shaped apertures 52 (FIGS. 2, 19, 20, 21). At their upper ends tabs 22 preferably have radially outwardly directed lips. As tabs 22 are inserted through apertures 52, the tabs flex radially inwardly until such time that lips pass completely through the apertures whereby the tabs assume their unflexed positions and the lips latchingly engage body member 11 with body member 7.

[0066] Alternatively, it will be understood that the lipped tabs or similar structure may be carried by the first body member 7 and corresponding slots may be provided, where appropriate, in the circumferential wall or the end wall of the second body member 11 in order to achieve the desired latching engagement between the first and second body members of the trimmer head housing.

[0067] Also shown in FIGS. 1, 2, 20, 26 are trimmer line metal eyelets 5 through which trimmer line passes when loading trimmer line into and discharging trimmer line from trimmer head 1 in the manner described hereinafter. The diametrically opposed metal eyelets 5 are securely mounted between the circumferential wall of the first and second body members 7 and 11.

[0068] Metal eyelets 5 are preferably provided with a gently curved contour to reduce breakage of the trimmer line during operation of trimmer head 1. As depicted in FIGS. 19, 20 and 21 main body member 7 includes a central opening 50. Prior to assembly of trimmer head 1, the threaded arbor of a trimmer apparatus drive shaft is inserted through opening 50 and a fastener (nut/bolt) 6 is threaded onto the drive shaft arbor which secures body member 7 to the threaded drive shaft arbor. Trimmer head 1 further includes a trimmer line spool 8 that is rotatably supported in the trimmer head housing. Spool 8 comprises a cylindrical core bounded on its first and second (upper and lower) ends by circular disc-like flanges 17 and 16. According to this embodiment, spool 8 comprises a multiple chamber spool, that is, it is divided into two chambers or compartments by the provision an intermediate flange 32 located between flanges 17 and 16. Intermediate flange 32 is preferably coplanar with abutment means 37 (FIGS. 18, 23, 22), discussed below, provided within the core of spool 8. Abutment means 37 serves as an abutment or seat for resilient biasing means 9 e.g., a compression spring or the like, in a manner described below. In addition to biasing means 9, the latch means according to the embodiment of trimmer head 1 illustrated in FIGS. 1-26 comprise at least one projection 18, 15 carried by one of the trimmer head housing and or spool 8. The projection(s) cooperate with seat means in the form of at least one recess carried by the other of the trimmer head housing and the spool. Together the latch means and seat means function as indexing means to enable a user to selectively discharge trimmer line from the spool when desired or necessary. According to a presently preferred embodiment most clearly illustrated in FIGS. 1, 6, 7, 11, 14, 17, 18, 22, 23 and projection(s) 18 and 15 assume the form of generally arcuate wedge shaped formation(s) provided on the outer faces of both of the trimmer spool end flanges 17, 16. Each formation includes a substantially vertical stop surface and a sloped or inclined cam or glide surface. Preferably, the formation(s) are molded integrally into spool 8 at the time of its manufacture. In a presently preferred embodiment most clearly illustrated in FIGS. 6, 7 and 11 projection(s) 18, 15 are adapted to cooperate with seat means in the form of generally arcuate and or vertical depressions 26, 58 provided on the inner face of both first and second housing body member 11, 7. A projection 18, 15 received in a depression 26, 58 is shown in FIG. 1. It will be understood that the relative positions of the projection(s) 18, 15 and depression(s) 26,58 may be reversed. That is, suitable sloped projection(s) may be provided in the inner faces of the first and second body member 7, 11 and cooperating depression(s) may be formed in the outer faces of both of the trimmer spool end flanges 17, 16. Projection(s) 18, 15 are normally retained in depression(s) 26, 58 under the influence of the compression force of biasing means 9.

[0069] In order to maintain biasing means 9 in stable orientation during operation of trimmer head 1, it is desirable that the bottom surface of first body member 7 be provided with a protruding ring or collar 251 the function of which is described below. In presently available spool trimmer head assemblies wherein the trimmer line may be wound onto a spool without disassembly of trimmer head housing to reload line onto the inner spool that easy load, these spool trimmer heads are uni-directional and can only function properly on a trimmer machine which drive shaft arbor turns in one (1) specific direction (clock-wise or counter clockwise).

[0070] In contrast, trimmer line spool 8 may be received in the trimmer head housing with either spool flange 16 or spool flange 17 in operative engagement with the inner surface of body member 11. That is, spool 8 may be selectively placed in a desired disposition in body member 11 depending on the direction of rotation of the drive shaft of the trimmer apparatus with which trimmer head 1 is intended to be used (FIG. 11). Once the desired disposition of spool 8 has been determined a small removable (i.e., friction fit) semi-permanent type insert stop 19 (FIGS. 1, 5, 14, 15, 22) can be placed in receiver openings 31,48 provided in spool center non-circular opening which acts as a block for misplacement of the spool 8 in the trimmer head housing 11, incorrectly. This insert stop can be permanently placed or non-permanently placed (i.e. removable). It would be made from plastic or rubber type material but not limited to. Accordingly, the cam surface(s) of the projection(s) 18, 15 on the flanges 17, 16 are inclined in such a way that spool 8 is capable of practical rotation in one direction (e.g., counterclockwise) when first flange 17 faces upwardly and practical rotation in the opposite direction (e.g., clockwise) when second flange 16 faces upwardly (FIG. 11).

[0071] With this capability, this spool trimmer head may be effectively used with essentially any powered vegetation trimmer, regardless of whether the trimmer's drive shaft rotates clockwise or counterclockwise. Referring to FIGS. 6, 7, 14, 17, 18, 22, 23 and 27, it will be seen that, extending inwardly from the outer surfaces of spool flanges 16, 17 and terminating at abutment means 37 is a pair of opposed sockets 64. In the illustrated embodiment, sockets 64 have a generally noncircular shape. Referring to FIGS. 3, 8, 24, 25 there is shown a trimmer spool turning member 12 suitable for enabling a user to wind trimmer line onto spool 8. Trimmer spool turning member 12 comprises a knob portion 12 that is adapted to project through a central aperture 65 (FIGS. 3, 4) provided in the second body member 11. Knob portion 12 is preferably provided with a plurality of raised grip enhancing formations about its periphery. Trimmer spool turning member 12 further comprises a drive portion 37 which is separated from knob portion 12 by a radially outwardly directed flange 35. Flange 35 is adapted to rest against the inner face of the closed end of the second body portion 11. Preferably, the inner face of the closed end of the second body portion surrounding central aperture 65 is provided with a circular seat 66 (FIGS. 3 and 4) which is dimensioned to closely receive knob flange 35 in the manner shown in FIG. 3, drive portion 37 is sized and shaped to essentially matingly cooperate with sockets 64 of trimmer line spool 8. In the illustrated embodiment, therefore, the drive portion 37 of trimmer spool turning member 12 is generally a non-circular symmetric shape to permit its insertion into either of the spool sockets 64. It will be appreciated, however, that the mating spool sockets 64 and drive portion 37 are not limited to any particular shape. Indeed, they may assume any mating shape other than a purely circular configuration that will effectuate rotation of spool 8 by rotation of knob portion of 12. It should be noted that spool cover plate 28 (FIGS. 9, 10, 16, 17, 18) is placed in spool socket 64 of spool 8 by an assembly person/worker at plastic injection mold factory. 28 and 8 to be sold as preassembled.

[0072] Cover plate 28 has insert pegs 38 that are to be joined with receiver openings 67 within the spool socket that has open face U shaped non-linear portion of trimmer line guide channel exposed. Spool cover plate is a friction fit assembly and this part once placed cannot easily be removed and when the trimmer head is fully assembled this part is held in place either being biased by spring 9 and or abutment to 37 of bump/turn knob 12 which is also biased by spring 9. Metal Eyelets 5, (FIGS. 1, 2, 5, 20) are fixed and preassembled to main housing body 7 by an assembly person/worker. The eyelets simply slide in to a tapered side wall of main housing body 7 with a friction fit. The eyelets can be installed by hand without the use of tools and removed and replaced by hand as well. Assembly of trimmer head 1 is as follows. A user first inserts the knob portion of trimmer spool turning member 12 until knob flange 35 comes to rest against the inner face of the closed end of the second body portion 11. He or she then places trimmer line spool 8 into the second body portion 11 while bringing one of the spool sockets 64 into mating engagement with the drive portion of trimmer spool turning member 12. When inserting the spool, the user must take care to face either spool flange 17 or spool flange 16 upwardly depending on whether they have trimmer machine that has a drive shaft arbor that turns either clockwise or counterclockwise onto the spool (the direction of winding is dictated by the direction of rotation of the trimmer apparatus drive shaft: if the drive shaft rotates counterclockwise, then the trimmer line winding direction is clockwise, and vice versa). Instructional message and directional symbols 29 (FIGS. 14, 17, 18) are molded on spool flanges 17, 16 to aide user from misplacement of spool with 11 and 12. Biasing means 9 is then placed into the open upwardly facing socket 64 and first body member 7 is brought into closing engagement with second body member 11.

[0073] Each socket 64 is preferably provides for placement a small removable (i.e. friction fit) semi-permanent type insert stop 19 (FIGS. 1, 5, 14, 15, 22) can be placed in receiver openings 31,48 provided in spool center non-circular opening which acts as a block for misplacement of the spool 8 in the trimmer head housing 11, incorrectly. If an end user does not use or loses stop 19 and errors in properly placing the spool within the trimmer housing, the body member 7, 11 may be separated to permit the spool to be inverted into the proper disposition.

[0074] Referring again to FIGS. 26, 27, 17, 11, 14, 7 and 6, it will be seen that spool 8 when joined with spool cover plate 28 includes a continuous closed non-linear trimmer line guide passageway formed coplanar with intermediate spool flange 32. Trimmer line guide means is a continuous closed non-linear passageway passing from a first enlarged portion 10 of intermediate spool flange 32 through abutment means 33 (FIGS. 7, 6) and through a second (opposite end of spool) enlarged portion 10 of intermediate spool flange 32. As seen in FIGS. 26, 27, the passageway of trimmer line guide means communicates with oppositely oriented guide openings in the first and second enlarged portions 10 of intermediate flange 32 that are constructed and arranged to ensure that trimmer line is properly wound on both upper and lower chambers of spool 8 equally during reloading of trimmer line onto the spool 8. Also, it is preferable that the opposite open ends of the passageway of trimmer line guide means be funnel or flare shaped, as at 10 (FIGS. 6, 7, 11,) to facilitate insertion of trimmer line into the passageway. In order to load trimmer line 4 into trimmer head 1, the passageway of trimmer line guide means 10 is first brought into alignment with trimmer line exit ports (metal eyelets) 5. Then, using one fixed length of line long enough to fully load the inner spool 8 (note: use manufactures recommended length), take one end length of trimmer line and insert it into either eyelet 5 and by feed/push the line through trimmer line guide means of spool 8 until it passes out of the opposite exit eyelet 5. The trimmer line should then be adjusted so that approximately equal lengths of line project from each exit port. The user then winds the bump/turn knob portion 20 of the trimmer spool turning member 12 in the direction that is free to turn which turns the inner spool and the line is drawn into the housing and wound upon the upper and lower chambers of spool 8. The sloped surfaces of projections 18, 15 allows a person to be able to easily turn knob 12 which ratchets in one direction and cannot move in the opposite direction. As knob 12 is turned projections 18, 15 makes contact with indexing ribs 26 in bottom housing 11 that glide upward and over the rib and then drop in to the depression which locks the spool from turning in the opposite direction. As is known in the art, the substantially vertical stop faces of projections 18, 15 prevent uncontrolled discharge of trimmer line during vegetation trimming. Trimmer head 1 is a bump indexing variety of trimmer head. That is, it permits user-controlled discharge of trimmer line utilizing the centrifugal force generated by the rapidly rotating head. More particularly, when the bottom of knob portion 60 of the trimmer spool turning member 12 is tapped against a hard surface, the biasing force of biasing means 9 is momentarily overcome, whereby the substantially vertical stop faces of projections 18, 15 are momentarily displaced from contact with the corresponding substantially vertical stop faces of depressions 26. During this brief instant, centrifugal force cause trimmer line 4 to be discharged through metal eyelets 5. Thereafter, the biasing means 9 re-seats the spool into engaging contact between the stop faces of projections 18, 15 and their counterparts in depressions 26. It is also possible to use trimmer head 1 in a fully manual mode. As such, when the user desires to extract trimmer line from the head, he or she brings trimmer head to a complete stop, pushes the knob portion 60 inwardly against the biasing force of the biasing means while turning the knob and pulling on the line to extract the desired length of line from the spool. When sufficient line has been discharged, the user releases the knob and resumes trimming.

[0075] Referring simultaneously to FIG. 28, FIG. 29, and FIG. 30, a first exemplary trimmer head assembly 110 is shown. The trimmer head assembly 110 attaches to the drive shaft of a string trimmer machine (not shown), which may rotate the trimmer head assembly 110 either clockwise or counterclockwise depending upon the model of the string trimming machine being used. The trimmer head assembly 110 is comprised of three major molded plastic parts. The major plastic molded parts include a primary housing 112, a spool 114 and an end cap 116 that holds the spool 114 within the primary housing 112.

[0076] The primary housing 112 defines an open interior 118. The top surface 119 of the housing 112 is closed, except for a mounting hole that permits the passage of the drive shaft into the housing 112. The bottom of the housing 112 is open, therein providing easy access to the open interior 118 of the housing 112. The periphery of the open interior 118 of the housing 112 is defined by a cylindrical wall 119 that extends downwardly from the periphery of the top surface 119.

[0077] At least two string eyelets 120 are formed through the cylindrical wall 119. The string eyelets 120 are diametrically opposed. The housing 112 may contain thickened regions about each of the string eyelets 120 to compensate for the wearing of the plastic at the string eyelets 120. Furthermore, optional wear rings 122 may be provided within the string eyelets 120. The wear rings 122 can be made from metal, ceramic, or a hard plastic that resists contact wear better than does the plastic material of the remainder of the housing 112.

[0078] The spool 114 has a central hub 124. The central hub 124 is tubular in shape and has three primary flanges 126, 128, 130 that define two trimmer line winding areas 132, 134. A trimmer line conduit 136 is coupled to the central flange 130. The conduit 136 has a first open end 138 and an opposite second open end 139. The details of the conduit 136 are later explained.

[0079] The spool 114 passes into the interior 118 of the housing 112. The end cap 116 holds the spool 114 in place. The spool 114 has a projecting knob 140 that extends through an opening 142 in the end cap 116. Accordingly, when the spool 114 is assembled within the trimmer head assembly 110, the spool 114 can be manually rotated within the housing 112 by grasping and turning the projecting knob 140.

[0080] To load a length of trimmer line 144 onto the spool 114, the spool 114 is manually rotated until the two open ends 138, 139 of the conduit 136 align with the two eyelets 120. A free end 145 of the trimmer line 144 is then advanced into the conduit 136 through one of the eyelets 120. The advancement of the trimmer line 144 is continued until the trimmer line 144 emerges out of the opposite open end 139 of the conduit 136 and passes through the opposite eyelet 120. The trimmer line 144 can then be wound onto the spool 114 by rotating the protruding knob 140.

[0081] In order for the rewinding process to work, the open ends 138, 139 of the conduit 136 must be aligned with the eyelets 120 of the housing 112. Furthermore, the curved bias of the trimmer line 144 cannot cause binding within the conduit 136. In order to reduce the likelihood of binding, the curved bias in the trimmer line 144 is compensated for by the structure of the conduit 136.

[0082] Referring now solely to FIG. 30, it can be seen that the conduit 136 generally has an omega shape. That is, the conduit 136 has two straight sections 146, 148 and a curved central section 150. The first straight section 146 extends from the first open end 138 of the conduit 136 to the curved central section 150. Likewise, the second straight section 148 extends from the second open end 139 of the conduit 136 to the curved central section 150. The combined length of the straight sections 146, 148 is at least as long as the distance D1 between the straight sections 146, 148 that is occupied by the curved central section 150.

[0083] Each straight section 146, 148 is linearly aligned with each other and lays perpendicular to the exit planes of the open ends 138, 139. The curved central section 150 begins at an upward bend 151 having a first radius of curvature R1. The upward bend 151 transitions into a downward bend 152 having a second radius of curvature R2. Lastly, the downward bend 152 transitions into a lateral bend 153 that reorients the conduit 136 back onto its original direction. The lateral bend 153 has a third radius of curvature R3. The radii of the various bends 151, 152, 153 depend upon the radius of the central opening 142 in the spool 114. It is preferred that the various radii be between 5 percent and 20 percent larger than the radius of the central opening 142. In this manner, the curved central section 150 remains relatively close to the exterior of the central opening 142.

[0084] When the trimmer line 144 enters the first straight section 146, the first straight section 146 guides the trimmer line 144 into the curved central section 150. When the trimmer line 144 exits the curved central section 146, the trimmer line enters the second straight section 148. The second straight section 148 has a long enough length to eliminate any bias curvature embedded within the plastic of the trimmer line 144. Accordingly, when the trimmer line 144 exits the second straight section 148, the trimmer line 144 has been set on a straight path and reaches the second housing eyelet 120 without any binding.

[0085] In the embodiment described, a curved central section 150 is shown. If the incoming trimmer line 144 has a downward curve bias and the curved central section 150 curves upwardly, there is potential for the trimmer line 144 to bind. To eliminate this potential problem, two curved central sections can be made, wherein one is on either side of the central opening 142. Such an embodiment is shown in FIG. 31.

[0086] Since the alternate embodiment shown in FIG. 31 has many of the same features as the originally described embodiment, the same reference numbers will be used to describe the same features. Referring to FIG. 31, it can be seen that two curved sections 150, 160 can be created between the two straight sections 146, 148. When a segment of trimmer line 144 is inserted onto one of the straight sections 146, 148 and that segment reaches the two central curved sections 150, 160, the natural curved bias of the trimmer line 144 will cause the trimmer line 144 to enter either the first central curved section 150 or the second central curved section 160. Since the natural curved bias of the trimmer line 144 creates the selection, the trimmer line 144 is not guided against its bias and the potential for binding is removed.

[0087] In the embodiments previously described, the conduits are completely enclosed between their open ends 138, 139. This need not be the case. Parts of the conduit can be fabricated in an open fashion. Such fabrication may also result in simplified and less expensive molding tools.

[0088] Referring to FIG. 32, a third alternate embodiment of the present invention is shown. In this embodiment, a spool 170 is provided having a flange 172. A relief 174 is formed in the flange 172 of the spool 170 around the central opening 176. The relief 174 has a general rhombus shape with rounded corners. The central opening 176 is disposed in the center of the relief 174. Two deflectors 178, 179 are set within the relief 174. Both deflectors 178, 179 have an offset salient point 180. The offset salient point and the angles of the deflectors 178, 179 act to deflect the trimmer line 144 to the right of the salient point 180 as the trimmer line 144 approaches the salient point 180.

[0089] The relief 174, being generally shaped as a rhombus, has a long axis 182 between corners 183, 184 and a short axis 185 between corners 186, 187. Straight sections 188, 190 of the conduit lead into the relief 174 in the same line as the long axis 182. The straight sections 188, 189 of the conduit extend to open ends 192, 193 at the edge of the flange 172. These open ends 192, 193 are aligned with the eyelets 120 in the surrounding housing 112 of the trimmer head assembly when new trimmer line 144 is loaded into the trimmer head assembly.

[0090] Referring to FIGS. 33a and 33b, it can be seen that when a length of trimmer line 144 is inserted through the eyelet 120 of the housing 112 and through a straight section 188 of conduit, the free end 145 of the trimmer line 144 enters the relief 174. The trimmer line 144 advances until the trimmer line 144 contacts the salient point 180 of the deflector 178. The deflector 178 deflects the trimmer line 144 to the right of the deflector 178. The trimmer line 144 then contacts the peripheral wall 194 of the relief 174 and follows the path of that wall 194. The wall 194 of the relief 174 guides the trimmer line 144 into the opposite straight section 190.

[0091] It will be understood that two deflectors 178, 179 are provided, so it does not matter in which direction the trimmer line 144 is inserted into the trimmer head. A left-to-right insertion and right-to-left insertion operate in the same manner.

[0092] As with the earlier embodiments, the combined length of the straight sections 188, 190 of the conduit are preferably longer that the distance D2 between the straight sections 188, 190 of conduit. In the shown embodiment, this distance corresponds to the long axis 182 of the relief 174.

[0093] It will be understood that the embodiments of the present invention that are illustrated and described are merely exemplary and that a person skilled in the art can make many variations to those embodiments. For instance, radius of curvatures used in the curved section of the conduit path can be varied to accommodate different spool diameters with different sized central openings. All such embodiments are intended to be included within the scope of the present invention as defined by the claims.