Patent Publication Number: US-2004049925-A1

Title: Pole pruner

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001] The present invention relates generally to the field of lawn and garden tools and, more particularly, to a pole pruner.  
       BACKGROUND OF THE INVENTION  
       [0002] Pruning trees and other types of vegetation is often a tiresome and dangerous task. For example, trees and other types of elevated vegetation may require the use of an elevated support. Additionally, the location of vegetation may require a great deal of physical exertion by a user of a cutting device to extend the cutting device to reach the vegetation. Extended pruners have been developed to alleviate some of the dangers inherent in vegetation trimming. However, extended pruners are generally heavy and cumbersome. Additionally, noise and vibration may result in difficulty in operating extended pruners.  
       SUMMARY OF THE INVENTION  
       [0003] In accordance with the present invention, a pole pruner that is lighter in weight than professional-grade pole pruners is provided, thereby making available a consumer-grade a pole pruner that is lightweight, low in cost, and easy to use. Additionally, a pole pruner according to one aspect of the present invention has a compact and contoured profile, thereby substantially preventing the pole pruner from becoming lodged or ensnared in tree limbs or other vegetation. Further, a pole pruner according to another aspect of the present invention includes a gear design that reduces noise and produces less vibration than prior pole pruners. Additional aspects and advantages of the invention will be apparent from the following descriptions taken in connection with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0004] For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:  
     [0005]FIG. 1 is a diagram illustrating an embodiment of a pole pruner;  
     [0006]FIGS. 2A and 2B are diagrams illustrating a view of an embodiment of a cutting head of the pole pruner illustrated in FIG. 1;  
     [0007]FIGS. 3A and 3B are diagrams illustrating an exploded view of the cutting head illustrated in FIGS. 2A and 2B;  
     [0008]FIG. 4 is a diagram illustrating a cross-sectional view of a portion of the cutting head illustrated in FIGS. 2 and 3 taken along the line  4 - 4  of FIG. 2.  
     [0009]FIG. 5 is a diagram illustrating a cross-sectional view of an embodiment of a gear assembly of the cutting head illustrated in FIGS. 2 and 3. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0010] The preferred embodiments of the present invention and the advantages thereof are best understood by referring to FIGS.  1 - 5  of the drawings, like numerals being used for like and corresponding parts of the various drawings.  
     [0011]FIG. 1 is a diagram illustrating a pole pruner  10 . As illustrated in FIG. 1, pole pruner  10  comprises a cutting head  14  coupled to a forward portion of a boom  16 . A power supply  18  is coupled to a rearward portion of boom  16 . In FIG. 1, boom  16  comprises a plurality of boom units  20  joined together by a coupling  22 . However, it should be understood that a single boom unit  20  may be: used to form boom  16 . A handle  24  is medially disposed along boom  16  to accommodate manipulation of pole pruner  10  during use. In the illustrated embodiment, power supply  18  comprises a gas-powered engine  30  disposed within a housing  32 . Engine  30  outputs a rotational force to one or more drive shafts  34  disposed within boom  16 . Housing  32  may also comprise a handle  36  for manipulating pole pruner  10  during use.  
     [0012]FIGS. 2 and 3 are diagrams illustrating an embodiment of cutting head  14 . In the illustrated embodiment, cutting head  14  comprises a gear housing  40  formed by an upper housing portion  44  and a lower housing portion  46 . Upper housing portion  44  comprises an outwardly extending hub  48  adapted to extend through an opening  50  disposed in a bar clamp or chain cover  42  to secure a bar pad bracket  52  and a chain guide  54  between chain cover  42  and upper housing portion  44 . In operation, chain guide  54  supports rotation of cutting chain  56  about chain guide  54  for cutting vegetation.  
     [0013] Cutting head  14  also comprises a gear assembly  58  for communicating rotary power received from power supply  18  and/or boom  16  to cutting chain  56 . In the illustrated embodiment, gear assembly  58  comprises an input gear assembly  60  and an output shaft gear assembly  62 . Input gear assembly  60  is disposed at a rearward portion  64  of housing  40  and is adapted to receive the rotational force from a drive shaft  34  of boom  16 . Input gear assembly  60  is coupled to output shaft gear assembly  62  for transmitting the rotational force to cutting chain  56 . In operation, input gear assembly  60  may be directly coupled to a drive shaft  34  of boom  16  or may be otherwise coupled to boom  16  to receive the rotational force from a drive shaft  34  of boom  16 . In the illustrated embodiment, input gear assembly  60  comprises a radial bearing  70  and an input bevel gear  72  disposed along an input shaft  74 . Output shaft gear assembly  62  comprises a radial bearing  80  disposed outboard of an output bevel gear  82 , and a worm gear  84  disposed inboard of the output bevel gear  82 . The bearing  80 , bevel gear  82  and worm gear  84  are disposed along an output shaft  86 . Input gear assembly  60  and output shaft gear assembly  62  are disposed perpendicular to each other in the illustrated embodiment having gears  72  and  82  adapted to engage each other to transmit the rotational force from the drive shaft  34  of boom  16  to the cutting chain  56 .  
     [0014] Upper housing portion  44  and lower housing portion  46  are formed having integral support surfaces adapted to support bearings  70  and  80  such that input gear assembly  60  and output shaft gear assembly  62  are disposed between upper housing portion  44  and lower housing portion  46 . An outboard portion  88  of output shaft  86  extends through a washer  90  and into a sprocket  92 . Sprocket  92  may be secured to output shaft  86  using a retainer clip or other type of coupling device (not explicitly shown). Cutting chain  56  engages teeth  98  of sprocket  92  such that rotation of output shaft gear assembly  62  relative to housing  40  correspondingly rotates and drives cutting chain  56  about chain guide  54 .  
     [0015] Cutting head  14  also comprises an oil pump  94  for delivering oil to cutting chain  56 . In the illustrated embodiment, oil pump  94  comprises a plunger assembly  102 ; however, it should be understood that other types of oil pumping mechanisms may be used. As best illustrated in FIGS. 3A and 3B, worm gear  84  is disposed near an inboard portion  100  of output shaft  86  for engaging plunger assembly  102 . Plunger assembly  102  draws oil for lubrication of cutting chain  56  from a detachable oil reservoir  104  disposed near a forward portion  105  of housing  40  and attached to upper housing portion  44 . A bearing  106  supports inboard portion  100  of output shaft  86 . In the illustrated embodiment, worm gear  84  comprises a spring  108 ; however, other devices or structures may be used to form worm gear  84  or, alternatively, worm gear  84  may be integrally formed onto output shaft  86 . Additionally, in the illustrated embodiment, oil reservoir  104  comprises a rearwardly extending upper portion  110  and a rearwardly extending lower portion  111  disposed about a portion of oil pump  94 . For example, in the illustrated embodiment, a portion of oil pump  94  is disposed between portions  110  and  111 , thereby protecting oil pump  94  from potential damage caused by vegetation.  
     [0016] Referring to FIGS. 3A and 3B, plunger assembly  102  is adapted to rotate and reciprocate within a barrel  112  to draw oil from oil reservoir  104 . For example, in the illustrated embodiment, plunger assembly  102  comprises a gear  120  adapted to engage worm gear  84  to rotate plunger assembly  102  relative to barrel  112 . A shaft  122  of plunger assembly  102  extends forwardly from gear  120  into barrel  112 . Shaft  122  comprises an integrally formed scoop portion  124  such that rotation of shaft  122  within barrel  112  causes scoop portion  124  to draw oil about an internal periphery of barrel  112 . To obtain reciprocation of plunger assembly  102  relative to barrel  112 , plunger assembly  102  comprises an irregularly shaped groove  130  adapted to engage a stationary pin  140 . For example, in the illustrated embodiment, groove  130  is disposed at a non-perpendicular angle relative to an axis  132  of plunger assembly  102 . In operation, groove  130  engages pin  140  disposed in a fixed position within housing  40  such that in response to rotational movement of plunger assembly  102  about axis  132 , plunger assembly  102  reciprocates along axis  132  corresponding to the position of groove  130  relative to pin  140 . Pin  140  may comprise a discrete structural component within housing  40  or may comprise an integrally formed structure of housing  140 .  
     [0017] In FIGS. 3A and 3B, barrel  112  is coupled to an oil block  152 . Oil block  152  is coupled to a fitting  154  and an oil pickup assembly  156  extending into oil reservoir  104 . Barrel  112  is disposed within an opening  158  of oil block  152 . Oil pickup assembly  156  comprises a tube  160  disposed within oil reservoir  104  and a filter element  162  disposed over a portion of tube  160  to filter oil entering tube  160 . A plug  164  is disposed at a distal end of tube  160  to prevent oil from entering tube  160  from bypassing filter  162 . A fitting  170  of oil pickup assembly  156  engages fitting  154  such that a wall of oil reservoir  104  is disposed between fitting  170  and fitting  154 . Seals or other members may be used about fittings  154  and  170  to prevent oil from leaking around fittings  154  and  170 . Thus, in operation, fitting  154  extends through an opening in a wall of oil reservoir  104  and into corresponding fitting  170 . An opposite end of fitting  154  engages an opening  172  of oil block  152 . Oil block  152  retains the oil drawn from reservoir  104  until the oil is distributed via plunger assembly  102 , thereby preventing the oil from entering undesired portions of housing  40 .  
     [0018] In operation, rotation of output shaft gear assembly  62  causes engagement of worm gear  84  with gear  120  of plunger assembly  102 , thereby causing rotation of plunger assembly  102  about axis  132 . During rotation of plunger assembly  102  about axis  132 , interaction of pin  140  with groove  130  causes reciprocation of shaft  122  within barrel  112 . As plunger assembly  102  reciprocates rearwardly or outwardly relative to barrel  112 , vacuum pressure within barrel  112  draws oil from oil reservoir  104  through oil pickup assembly  156 . Oil is then drawn into barrel  112  from oil pickup assembly  156  and into oil block  152  via an opening  174  in a wall of barrel  112 . As plunger assembly  102  continues rotating within barrel  112 , scoop portion  124  of shaft  122  draws the oil about the internal periphery of barrel  112 . Additionally, as plunger assembly  102  reciprocates forwardly or inwardly within barrel  112 , shaft  122  compresses the oil disposed within barrel  112  and forces the oil outwardly from within barrel  112  via an opening  176  in a wall of barrel  112 .  
     [0019]FIG. 4 is a diagram illustrating a cross-sectional view of a portion of cutting head  14  taken along the line  4 - 4  of FIG. 2A. As illustrated in FIG. 4, upper housing portion  44  comprises an integrally formed channel  177  for delivering oil from oil block  152  to cutting chain  56 . For example, upper housing portion  44  comprises an integrally formed recess area  178  formed at an outboard end of channel  177  and adapted to receive oil block  152 . Oil block  152  comprises a sealing member  179  adapted to form a seal between oil block  152  and recess area  178  to substantially prevent oil from exiting channel  177  around oil block  152 . Sealing member  179  may comprise an integrally formed member of oil block  152  or may be a separate and discrete member. Referring to FIG. 3B, channel  177  transitions into a longitudinally extending outlet  180  as channel  177  extends inwardly toward cutting chain  56 . Thus, in accordance with the present invention, oil is delivered to cutting chain  56  via channel  177  formed in upper housing portion  44 , thereby alleviating a requirement of a separate oil line or tube leading to cutting chain  56 .  
     [0020] Referring to FIGS. 2 and 3, cutting head  14  is configured having a contoured profile converging inwardly to substantially prevent pole pruner  10  from becoming lodged or ensnared by tree limbs or other vegetation during use. For example, an upper surface  181  and a side surface  182  of upper housing portion  44  converge inwardly as surfaces  181  and  182  extend toward rearward portion  64  of housing  40 . Additionally, a side surface  183  and a lower surface  184  of lower housing portion  46  also converge inwardly as surfaces  183  and  184  extend toward rearward portion  64  of housing  40 . Further, a lower surface  185 , a side surface  186 , and an upper surface  187  of chain cover  42  each converge inwardly as surfaces  185 ,  186  and  187  extend rearwardly toward boom  16 . Thus, housing portions  44  and  46  and chain cover  42  are configured having a contoured profile such that the assembled portions converge inwardly toward rearward portion  64  as portions  44  and  46  and chain cover  42  extend toward rearward portion  64 . Thus, when extracting cutting head  14  from vegetation, the converging profile of cutting head  14  substantially reduces the likelihood of the cutting head  14  becoming lodged or ensnared by the vegetation.  
     [0021] Additionally, oil reservoir  104  is located on cutting head  14  in a position to avoid entanglement of the cutting head  14  by vegetation. For example, in the illustrated embodiment, oil reservoir  104  is disposed toward forward portion  105  of housing  40  and forward of upper housing portion  44 . Thus, when drawing cutting head  14  away from vegetation, upper housing portion  44  shields oil reservoir  104  from the vegetation, thereby allowing cutting head  14  to be easily withdrawn from the vegetation and reducing the likelihood that oil reservoir  104  will cause cutting head  14  to become ensnared by the vegetation. Further, oil reservoir is configured having a profile coincident with the profile of upper housing portion  44  and lower housing portion  46  to further reduce the likelihood of cutting head  14  becoming ensnared by the vegetation upon withdrawal of cutting head  14  from vegetation. For example, as best illustrated in FIGS. 2 and 3, oil reservoir comprises an upper surface  188  curving or sloping downwardly coincident with surface  181  of upper housing portion  42  and a lower surface  189  curving or sloping sloping upwardly coincident with surface  184  of lower housing portion  44 . Thus, oil reservoir  104  is configured having tapered surfaces  188  and  189  that converge towards each other to form a reduced profile as the profile extends rearwardly.  
     [0022]FIG. 5 is a diagram illustrating an embodiment of input gear  72  and output gear  82 . For ease of description, only input gear  72  is illustrated and described. However, it should be understood that the description corresponding to FIG. 4 and input gear  72  applies also to output gear  82 .  
     [0023] As illustrated in FIG. 5, input gear  72  comprises a plurality of teeth  190  for engaging corresponding teeth of output gear  82 . Teeth  190  of input gear  72  are formed having a pitch circle indicated generally at  191  and a tooth dedendum indicated generally at  192  extending from the pitch circle  191  to a bottom land  194  of input gear  72 . Using standard or conventional gear design principles, a tooth addendum indicated generally at  196  extends from a standard or conventional location of a top land indicated generally at  198  to pitch circle  191 . In accordance with the present invention, however, input gear  72  is configured having a reduced addendum indicated generally at  200  from standard gearing design principles, thereby forming top land  202 . For example, in the illustrated embodiment, the reduced addendum  200  of input gear  72  is formed offset a predetermined distance from standard gearing top land  198  and parallel to top land  198 . In this embodiment, top land  202  is offset from standard gearing top land  198  by approximately 0.011 inches to form reduced addendum  200  to reduce noise and vibration associated with interaction of gears  72  and  82 ; however, it should be understood that other dimensional offsets may be used to form reduced addendum  200 . For example, as plastic or other lightweight materials are used to form components such as housing  40 , factors such as the type of material, heating and cooling properties affecting expansion and contraction of the material, cycle times, and wall thickness may affect the operating conditions of gears  72  and  82 . Thus, reduced addendum  200  generates an additional clearance between gears  72  and  82  to reduce noise and vibration during operation of device  10 .