Abstract:
An easily engageable and releasable chainsaw bar guard for protecting an individual carrying a chainsaw and for preventing damage to the cutter chain and saw dogs of a chainsaw. The bar guard comprises an elongated stiff hollow sleeve whose interior space is just slightly larger than the bar and chain to be protected. The sleeve has an opening at the proximal end for sliding the sleeve onto the guide bar, and is closed at the other end to protect the end of the bar and cutter chain. A snap-clip mechanism is fixed to the sleeve for releasably latching the proximal end of the guard to the chainsaw. The snap-clip mechanism biases a retaining claw into contact with the chainsaw bar between the nuts on the saw bar attachment/adjustment bolts. The sleeve and the snap-clip mechanism can be selectively configured to accommodate chainsaw bars of different shapes and dimensions and the spacing of whose guide bar adjustment nuts varies. The guard may optionally be provided with clips, pockets or containers for storing chainsaw tools.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a protective guard for conventional portable chainsaws, including those with saw dogs. This invention is suitable for use when a chainsaw is carried, transported, or stored, thereby reducing the possibility of injury to the individual carrying or handling the chainsaw, and also reducing the possibility of damaging the cutter chain or saw dogs of the chainsaw during such activities.  
           [0003]    2. Description of the Prior Art  
           [0004]    Because of the sharp edges of cutter chains and also of saw dogs when present on conventional chainsaws, chainsaws may cause injuries to the individuals carrying or handling the chainsaws, and their sharp edges may be damaged by unintended contact with objects.  
           [0005]    One way previously proposed to minimize the risk of such injuries and damage was to place a chainsaw in a sealed portable case or similar container. However, the substantial weight and volume of such cases rendered them unattractive to individuals using them, especially loggers, who frequently have to carry chainsaws on foot to working sites. Exemplary such cases are described in Schurman U.S. Pat. No. 4,369,575 granted Jan. 25, 1983, Reynolds U.S. Pat. No. 5,119,937 granted Jun. 9, 1992, and Griffin U.S. Design Pat. No. 359,849 granted Jul. 4, 1995.  
           [0006]    Another way previously proposed to prevent such injuries was to provide a guard, sheath, or the like to limit access to the cutter chain. However, in many such proposed devices, the protection of the individual primarily sought was protection during the sawing operation, not primarily protection during carrying or transporting the chainsaws. For example, many bar guards, sheaths, or the like were designed to prevent kickback when operating the chainsaw. Therefore, a portion of the cutter chain was always exposed when using such devices; the possibility of damage or injury during transportation was not prevented. An exemplary such partially open guard is illustrated in Holzworth U.S. Pat. No. 4,193,193 granted Mar. 18, 1980. A similar such guard hingedly connected to the saw is described in Shivers U.S. Pat. No. 4,621,426 granted Nov. 11, 1986. The Shivers bar guard is expensive and awkward to use; it remains attached to the saw during the sawing operation while it is pivoted upwards away from the guard, interfering with the operator&#39;s view of the log or other workpiece.  
           [0007]    Other such protective devices often required some modification of the chainsaw itself. By way of example, in Otoupalik U.S. Pat. No. 3,042,087 granted Jul. 3, 1962, a protective sheath was designed to be removably attached to the chainsaw by a pair of removable tension springs. The cutter chain was completely sealed when the sheath was attached. However, the primary objective of the above mentioned invention was to protect the cutter chain and guide bar from damage during transportation of the chainsaw. As a result, the combined chainsaw and guard remained hazardous to the person carrying the chainsaw with the sheath thereon. For example, since the tension springs were hooked onto the chainsaw handle bar, the springs often interfered with carrying the chainsaw. Further, when the sheath was attached, the tension springs were always in extension. Thus, it was quite possible that the person carrying the chainsaw with the sheath thereon might be injured by the tension spring if it were accidentally dislodged. Finally, the sheath was not intended to cover saw dogs, and in fact, the tension springs extended in the vicinity of the saw dogs when they were attached to the handle bars. Therefore, simply by using the prior Otoupalik device, the risk of at least some types of injury increased.  
           [0008]    An expensive and complex solution to the chainsaw guard protection problem is illustrated in Woleslagle U.S. Pat. No. 2,683,944 granted May 19, 1953. The telescoping sheath described by Woleslagle is awkward to use and necessarily bulky at one end to accommodate the series of telescoping elements when they are collapsed.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention is a detachable bar guard that is inexpensive to manufacture, easy to attach to and detach from the chainsaw, secure when in place on the chainsaw bar, fully protective of both the cutter chain and the individual carrying the saw, including protection for and from saw dogs when present, lightweight and unobstructive.  
           [0010]    A preferred embodiment of the invention comprises an elongate sleeve or sheath that shields substantially all normally exposed portions of the cutter chain on the guard bar, and also may be configured to provide the same shielding to saw dogs if present. Optionally, the flat of the sleeve may be provided with open areas to reduce weight. The proximal end of the sleeve is provided with a snap-clip mechanism to attach the sleeve to the chainsaw.  
           [0011]    The inventor recognized that most chainsaws are designed to mount the bar to the saw housing or frame by means of a pair of spaced attachment/adjustment bolts that engage mating slots in the bar; as the chain wears and becomes looser, the nuts on the bolts are loosened and the bar is then moved distally relative to the driving sprocket of the chainsaw so as to tighten the chain on the bar. These adjustment nuts are invariably or almost invariably exposed to easy access to facilitate bar position adjustment. Further, although not quite uniformly placed or spaced from one saw design to another, the nuts are placed and spaced quite similarly from one chainsaw to another.  
           [0012]    Accordingly, it is possible to provide a snap-clip mechanism on a sleeve according to the invention that mates with the retainer space between sequential adjustment nuts and that may be adjustable or adaptable to suit a range of chainsaws. The snap-clip mechanism includes a retaining claw that is biased into contact with the chainsaw frame or bar mounting plate or the like in the retainer space between the two bar guide adjustment nuts. The claw may be an elastic element fixed to or integral with the sleeve and configured so that under the biasing force, the claw is normally retained in place between the adjustment nuts. Alternatively, the claw may be rigid but pivotally mounted on the sleeve for biased engagement; a suitable biasing means such as a coil spring provides the bias force.  
           [0013]    The claw/clip dimensions and configuration may be varied and selected to permit some longitudinal adaptability of the snap-clip mechanism to fit different chainsaws. Alternatively, the claw may be slidably mounted to the sleeve so that by sliding the claw into different mounting positions, it may fit different chainsaws. The sleeve may be oversized to fit both those bars in which there is little clearance between the chain and the interior walls of the sleeve and also smaller bars, or instead the sleeve may be made in a variety of sizes to fit bars of various standard lengths, or both.  
           [0014]    Many types of plastics material are suitable for manufacture of the sleeve; such materials are sufficiently rigid to provide good protection for the chain and saw dogs when manufactured with relatively thin, lightweight walls, sufficiently soft not to damage the saw teeth if impacting against the teeth, and sufficiently flexible that a claw formed integrally with the sleeve is easily deflected to permit engagement and disengagement of the claw with the retainer space between the adjustment nuts. A somewhat less expensive and generally satisfactory manufacture of the guard can be effected using sheet steel for the sleeve and welding the snap-fit mechanism thereto; this solution entails some slight risk of dulling saw teeth if and when they come into frictional or impact contact with the guard, but the risk is probably acceptable because the saw teeth become dull with use in any case.  
           [0015]    A sleeve-and-claw arrangement of the foregoing sort constitutes a secure bar guard protecting both the sawbar and the user that is easily secured to and released from the chainsaw, is lightweight, comfortable to someone carrying the chainsaw on the shoulder or otherwise, and inexpensive to manufacture. A claw arrangement of the foregoing sort constitutes an easily engageable and releasable means for attaching the bar guard to a chainsaw. Note that the snap-clip mechanism can be configured and positioned so that it does not significantly interfere with the carrying of the chainsaw. The snap-clip mechanism can be selectively configured to accommodate chainsaws of different manufacturers whose guide bar adjustment nuts are spaced differently from the proximal end of the guide bar and from one another.  
           [0016]    While the foregoing is the preferred embodiment, it can readily be recognized that modifications and variants are possible within the foregoing inventive concept. For example, the sleeve could be made as a telescoping sleeve made of, say, three mutually slidable and overlapping elements so that a single guard could fit bars of several different standard lengths. That alternative would undesirably add to the weight, manufacturing cost, complexity (which would probably have a deleterious effect on the mechanical reliability of the sleeve) and bulk of the guard. Or the sleeve could be provided with a notch engageable by a claw mounted on one or both of the adjustment nuts. That alternative is considered undesirable because it could lead to premature loosening of one or both nuts and would interfere with the bar adjustment process. Further alternatives within the general scope of the invention will occur to those skilled in the design of equipment of this sort.  
           [0017]    The guard may optionally be provided with clips, pockets or containers for storing chainsaw tools. Such auxiliary elements, if provided, should preferably be located at the distal end of the guard so that they do not interfere with carrying the chainsaw (with guard attached) on the shoulder. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1A is a schematic side elevation view of a conventional chainsaw having a bar guard structured in accordance with one embodiment of the present invention.  
         [0019]    [0019]FIG. 1B is a schematic bottom view of the chainsaw and guard of FIG. 1A.  
         [0020]    [0020]FIG. 2A is a schematic side elevation view of a conventional chain saw having a guide-bar guard structured in accordance with a preferred alternative embodiment of the present invention.  
         [0021]    [0021]FIG. 2B is a schematic bottom view of the chainsaw and guard of FIG. 2A.  
         [0022]    [0022]FIG. 3A is a schematic bottom fragment detail view of a preferred embodiment of a snap-clip mechanism of the type appearing in FIGS. 2A and 2B mounted on the bar guard of FIGS. 2A and 2B.  
         [0023]    [0023]FIG. 3B is a schematic bottom fragment detail view of a preferred embodiment of a snap-clip mechanism of the type appearing in FIGS. 2A and 2B mounted on the bar guard of FIGS. 2A and  2 B, differing from FIG. 3A in that the claw arm is of a length different from that of FIG. 3A.  
         [0024]    [0024]FIG. 4 is a schematic side elevation fragment view of a distal portion of a variant according to the invention of the bar guard of any of the preceding views showing auxiliary snap fastenings and chainsaw-servicing tool container mounted thereon. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0025]    Referring to FIGS. 1A, 1B,  2 A and  2 B, a conventional power chainsaw  10  is disclosed having a motor housing  12 , support handles  14  and  16 , a forwardly projecting guide bar  18  around the slotted perimeter of which is slidably mounted an endless cutter chain  20 , two guide bar adjustment nuts  22 ,  24 , and two saw dogs  26 ,  28  on either side of the guide bar  18 . The cutter chain is driven by a drive sprocket (not illustrated) within the housing  12 . The adjustment nuts  22 ,  24  mate with corresponding attachment/adjustment bolts (not specifically illustrated) that pass through cut-out slots in the guide bar  18  and pass through a chainsaw bar mounting plate or mounting frame element  15  attached to the housing  12  or attached to a frame portion of the chainsaw  10  not specifically illustrated, or constituting a part of such housing or frame, whereby the guide bar  18  is secured to the chainsaw frame or to the housing  12  and may be adjustably positioned relative thereto by loosening the nuts  22 ,  24  and repositioning the bar, which is slidable within limits relative to the bar mounting frame or plate  15  within the limits of the cut-out slots of the bar  18 . All of the foregoing elements of the chainsaw are conventional and their interrelationship is conventional. Since there is some variability in conventional chainsaw design, reference herein to, for example, a guide bar mounting frame  15  should be taken as embracing mechanical equivalents such as a plate or frame extension or housing extension or the like through which the guide bar mounting bolts pass.  
         [0026]    The preferred embodiments of the bar guard, disclosed in FIGS. 1A through 2B, each include an elongate sleeve  30  to the proximal end of which is fixed a snap-clip mechanism  32  for attaching the sleeve  30  to the chainsaw  10 . The snap-clip mechanism  32  is permanently attached to the sleeve  30 . Depending upon choice of materials, the mechanism  32  or at least its base can be manufactured integrally with the sleeve  30  or may be welded or otherwise bonded thereto.  
         [0027]    The sleeve  30  is configured to envelope the cutter chain  20  and is provided with a proximal opening  31  to permit the sleeve  30  to cover the cutter chain  20 . The sleeve  30  has about the same contour or shape as, but is slightly larger than, the guide bar  18  with the cutter chain  20  thereon, so that when the sleeve  30  is placed on the chainsaw, the entire length of the cutter chain  20  will be concealed and protected. Further, in order for the sleeve  30  to cover the saw dogs  26  and  28 , the sleeve  30  flares outwardly in the vicinity of the proximal opening  31  in the plane of the guide bar  18  so as to be wide enough in that portion to cover the saw dogs  26 ,  28 .  
         [0028]    Variations are possible in the construction of the sleeve  30 , which may be made of any strong, lightweight, durable material such as metal or plastic. Although it is possible to have a telescoping sleeve arrangement (not shown) that would enable a single manufactured sleeve of variable length to be used to cover and protect guide bars of different lengths, there are disadvantages in such an arrangement. First, a telescoping arrangement would give rise to a significant manufacturing cost. Second, its relative complexity and the existence of moving parts would present a risk of malfunction or damage to the bar guard. Finally, a telescoping sleeve arrangement would weigh more than a counterpart sleeve of fixed length, and would be oversized for chainsaws with shorter guide bars, in part because as guide bars become shorter, they also tend to become narrower. Thus, in the preferred embodiments of this invention, the length of the sleeve  30  would be fixed. A number of sleeves of different dimensions would be manufactured so that the manufactured set of bar guards would suit most popular models of chainsaws of given guide bar length.  
         [0029]    Further, it is possible to design a sleeve  30  that does not conceal the entire exposed length of the guide bar  18 ; a plurality of openings may be provided on the portion that covers the flat of the guide bar  18  (but not the chain  20 ) in order fully to protect the chain  20  while saving weight. However, the plurality of openings may serve to catch various foreign objects such as twigs, branches, or debris, and thereby create a hazard for the individual carrying a chainsaw with such partly open bar guard.  
         [0030]    The preferred embodiment of the snap-clip mechanism  32  (see FIGS. 2A, 2B,  3 A and  3 B) includes a mounting bracket  34  fixed to the sleeve  30  and a clip arm  36  pivotally mounted on the mounting bracket  34 . The clip arm  36  is integral with or fixed to a retaining claw  50  whose distal portion enters retainer space  17  between guide bar adjustment nuts  22 ,  24  and whose latch face  52  engages the distal nut  24 . Note that the retainer space  17  between the retainer nuts  22 ,  24  is inherent in conventional chainsaw design. Accordingly, a biased engagement of latch face  52  with the distal nut  24  bordering the retainer space  17  secures the sleeve  30  to the chainsaw  10 . The biasing means is described further below.  
         [0031]    The clip arm  36  is pivotally mounted on the mounting bracket  34  by a removable pin or screw  38 . Other clip arms  36  having various lengths of extension can then be substituted for that for the time being mounted on bracket  34 , each in selected sequence being pivotally mounted on the mounting bracket  34 , as disclosed in FIGS. 3A and 3B. Clip arms  36  each have a substantially identical claw  50  at the working end thereof, but if, say, longer clip arms  36  are typically needed for use with guide bars mounted by more widely spaced adjustment bolts and nuts  22 ,  24 , the claw  50  may be dimensioned and shaped accordingly. The design in each case is selected so that the retaining claw  50  can engage the retainer space  17  between the two guide bar adjustment nuts  22  and  24 ; the distal nut  24  acts as a stop against which latch edge  52  of the claw  50  bears to prevent the sleeve  30  from sliding distally off the guide bar  18 . Suitable shaping and dimensioning of the clip arm  36  and associated claw  50  may be selected for a family of such elements, thereby accommodating chainsaws of different manufacturers whose guide bar adjustment nuts  22  and  24  are spaced differently from the proximal end of the guide bar  18  and possibly also from one another.  
         [0032]    In the preferred embodiment of the snap-clip mechanism  32  disclosed in FIGS. 3A and 3B, a small coil compression spring  40  is removably mounted between the mounting bracket  34  and the clip arm  36  to bias the retaining claw  50  into the retainer space  17 ; it is of course necessary for this purpose that the compression spring  40  be located on the side of pivot pin  38  remote from the claw  50  if the spring is to exert the requisite bias. The spring  40  is removable to facilitate replacement of the clip  36 . Circular recessed seats  42  and  43  are respectively provided on the underside of the clip arm  36  and on the base of the mounting bracket  34  as spring mounting means for mounting the coil compression spring  40 .  
         [0033]    Variations of possible mounting means are possible, such as circular stud seats, or hooks. However, a recessed circular seat is preferable because it is cost-effective and facilitates easy re-installation of the spring  40  after replacement of a clip arm  36 . (Note that instead of a compression coil spring as described, a coil spring under tension could conceivably be connected between the near underside of the claw  50  and the neighbouring area of the base of the bracket  34 , but such arrangement would render replacement of the clip arm  36  more difficult, partly because of the need to provide a different attachment arrangement for the ends of such coil spring.)  
         [0034]    Referring again to FIGS. 3A and 3B, the retaining claw  50  has a terminating convex surface  51  and a plane latch surface  52 . The convex surface  51  facilitates overcoming the resistance offered by the distal adjustment nut  24  to sliding the retaining claw  50  inwardly thereover. Once the retaining claw  50  is engaged within the retainer space  17  between the two bar guard adjustment nuts  22  and  24 , the bias force provided by the clip mechanism  32  resists dislodgement of the claw  50  and thereby retains the sleeve  30  in place.  
         [0035]    An alternative less preferred embodiment of the snap-clip mechanism  32  is disclosed in FIG. 1B. In this preferred embodiment, the snap-clip mechanism  32  comprises a single elongate clip element  33  having the associated claw  50  formed integrally therewith, and with no separate mounting means. Instead, the clip  33  is permanently attached, preferably bonded or welded, depending upon choice of materials, to the sleeve  30 . Or the clip  33  may be formed integrally with the sleeve  30 . The biasing force for the clip  33  is provided by the inherent elasticity of the material of which the clip  33  is made; the clip  33  may bend and deflect to permit the claw  50  to slide over the distal nut  24 . In this embodiment, in order to accommodate chainsaws of different manufacturers whose guide bar adjustment nuts  22  and  24  are spaced differently from the proximal end of the guide bar  18 , the clip  33  can be pre-manufactured in a variety of lengths before being fixed to the sleeve  30 . Alternatively, this objective can be accomplished by giving the clip  33  a pronounced arcuate or bow profile (not shown; the bow profile in FIG. 1 is more gently arcuate). The pronounced bow profile permits the clip to flatten and extend so that its integral claw can reach a given retainer space  17  that is more remote than a space reachable by the claw when the bow is, in its rest position, most pronounced, in which position the overall length of the clip is of course at a rest minimum. Note that this “pronounced bow” solution to the adjustment problem requires that the central part of the clip protrude appreciably outwardly away from the guide bar  18  when the clip is in rest position; such design entails the risk of snagging the clip and is for that reason not preferred. Also, to afford ready flexibility of the clip, the clip may be made of material that is thinner than otherwise would be desired.  
         [0036]    Another possible solution (not shown) is to provide an elongate clip with an extended interconnection tail provided with a serious of spaced apertures. The clip could be slidably mounted in a mating bracket or recess on the sleeve; the bracket or recess could have a number of apertures mating with those of the clip tail through which fastening bolts or the like could pass, thereby permitting the distance from the retaining claw to the sleeve opening to be varied.  
         [0037]    The flat surface of the sleeve  30  may also be provided with containers, clips or other holding means for holding tools necessary for servicing chainsaw in the field. Preferably any such containers or the like should be located at the distal end of the sleeve  30  so that when the chainsaw is carried on one&#39;s shoulder, the containers, etc. do not make contact with the shoulder. In FIG. 4, by way of example, a tubular container  60  with a removable threaded cap  62  for holding chainsaw files (not shown) is attached to the distal portion of the sleeve  30  by a pair of straps  64  and  65 . The tubular container  60  could instead be attached to the sleeve  30  by a pair of snap fastenings fixed to the sleeve  30 , or may be molded into the sleeve  30  itself. In any of the mentioned embodiments, it is preferable that the tubular container  60  be held in such position that threaded cap  62  extends distally beyond the distal end of the sleeve  30  so that the cap  62  can be easily removed or replaced.  
         [0038]    By way of further exemplification, a sparkplug tool  70  is shown removably attached to the sleeve  30  by a snap bracket  72  and an eye  73  fixed to said elongated sleeve  30 .  
         [0039]    Further variants and modifications of the bar guard according to the invention will occur to those skilled in the design of such items. The scope of the invention is as defined in the appended claims. For simplicity of exposition, reference in the claims to mounting the guide bar on a “guide bar mounting frame” includes the possibility of mounting the guide bar on the motor housing or other suitable component of the chainsaw.