Abstract:
A lifting implement, such as a shovel has a handle and a load bearing member. The handle includes an articulated joint dividing the handle between a major portion and a lever portion. The lever is adapted to pivot within the range of an acute angle relative to the handle profile. The lever and the major portion of the handle each have a means for mounting a resilient member therebetween, where the resilient member is capable of absorbing shock and storing energy when urged by the pivoting of the lever within the range during the motion of lifting a load, and which stored energy is released when the load is being heaved by the implement. The handle may include a hand grip and a gripping portion on the major portion spaced from the articulated joint such that a triangle is formed with the hand grip, the gripping portion and the articulated joint at the apex of the triangle, wherein the apex of the triangle.

Description:
TECHNICAL FIELD 
       [0001]    The present application relates to shock-absorbing implement handles and, more specifically, to handles for lifting implements such as shovels. 
       BACKGROUND ART 
       [0002]    When a hand implement, such as a shovel, impacts against a dense substance such as ice or a rock, a shock may be imparted through the implement. Several devices have been identified which attempt to provide a cushion or shock absorber to the handle. For example U.S. Pat. No. 4,691,954 Shaud 1987; AU 9645895 Deliu 1997; U.S. Pat. No. 5,816,634 Jacobs et al; WO99/55135 Nicholl 1999 and GB2,371,513 Russell, all show handles with a linear compression device, usually a compression spring. 
         [0003]    Although a linear compression device, in an implement handle, may act as a shock absorber in axial type loads, I have improved on such devices by integrating a deflection feature using a resilient component to the implement handle to absorb lifting loads. Such a shovel is illustrated in my patent Canadian application CA 2,641,020. 
         [0004]    The devices shown and described in CA 2,641,020 add an articulated, resilient, leveraging feature, to the shovel handle, providing a force assisting boost allowing the user to heave the contents on the shovel much further, using the energy stored by the resilient device. 
       SUMMARY 
       [0005]    Applicant has made further improvements as described herein. 
         [0006]    In accordance with a general aspect, there is provided an elongated handle with a distal end and a proximal end. The handle having a handle profile and including an articulated joint at a minor distance from the proximal end dividing the handle between a major portion extending from the distal end to the joint, and, a lever portion extending from the joint to the proximal end. A first prehension zone provided at the proximal end of the lever and a second prehension zone on the major portion. The lever portion is adapted to pivot about the joint within the range of an acute angle relative to the handle profile, and the handle profile defines a triangle with the base extending between the first and second prehension zones and the joint forms the apex of the triangle. The lever and the major portion of the handle each mounting respective ends of a resilient member therebetween, wherein the resilient member is capable of storing energy when applied by the pivoting of the lever within the range during the motion of engaging a load characterized by the translation of the apex of the triangle with respect to the base causing the resilient member to absorb shock and store energy. 
         [0007]    In a more specific embodiment, the lever includes a recessed seat adjacent the joint and a pair of brackets facing each other from the opposite ends of the seat wherein a first bracket is fixed to the lever while the second bracket is fixed to the major portion of the handle; and a resilient member fixed to and extending between the pair of brackets overlying the seat wherein the tool handles lend themselves to being stacked. 
         [0008]    In another embodiment of the present invention the bracket in at least one of the lever and major portion of the handle is mobile while the resilient member is an elongated flexible member with one end portion engaged in the bracket that is mobile and the other end portion is engaged with the bracket in the other of the lever and major portion of the handle such that the length of the flexible member may be varied by adjusting the position of the at least one mobile bracket whereby the stiffness of the resilient member is adjusted. 
         [0009]    In another aspect there is an energy storing device for a lifting implement including a handle and a load bearing portion wherein the energy storing device includes a an articulated joint to be mounted to a proximal end of the handle; and the device forming a lever extending from the joint to a first prehension zone provided at the proximal end of the lever and a second prehension zone on the handle; the lever adapted to pivot about the joint within the range of an acute angle relative to the handle. The handle and the lever defining a triangle with the base extending between the first and second prehension zones and the joint forming the apex of the triangle; the lever and the handle each mounting respective ends of a resilient member therebetween, the resilient member capable of storing energy when applied by the pivoting of the lever within the range during the motion of engaging a load characterized by the translation of the apex of the triangle with respect to the base causing the resilient member to absorb shock and store energy. 
         [0010]    For clarity the following terms are explained in more detail: 
         [0000]    “handle profile” means the longitudinal axis of the elongated handle, if it was straight but the approximation of a straight line including the joint when curved the handle is curved. Although a curved ergonomic handle is shown in the drawings, it is intended that a straight linear handle, at least for the major portion, be straight.
 
“lifting implement” means any shovel blade, fork for hay, blade for a spade, hand plow for scraping or the like.
 
“Lifting” for the purposes of this description includes any use that the implement is subjected to such as lifting and heaving a load such as snow or soil; scraping snow or ice; breaking or chipping ice or hard snow; digging in soft or hard soil.
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Reference is now made to the accompanying drawings in which: 
           [0012]      FIG. 1  is a perspective view of one embodiment of a shovel in accordance with an embodiment, held by a user; 
           [0013]      FIG. 2  is a side elevation view of the shovel shown in  FIG. 1 , with the handle shown in two positions at opposite limits of the range of operation; 
           [0014]      FIG. 3  is an fragmentary, perspective view showing a detail of the shovel shown in  FIG. 1 ; 
           [0015]      FIG. 4  is a fragmentary, perspective, exploded view of the detail shown in  FIG. 3 ; 
           [0016]      FIG. 5  is a side elevational view of the detail shown in  FIG. 3 ; 
           [0017]      FIG. 6  is a side elevational view similar to  FIG. 5  but showing the detail in a different operative position; 
           [0018]      FIG. 7  is a fragmentary, perspective view of a cluster of shovels in accordance with the embodiment shown in  FIG. 1 , in a stacked position; 
           [0019]      FIG. 8  is a fragmentary, side elevational view of another embodiment of the of the handle; 
           [0020]      FIG. 9 a    is a fragmentary, side elevational view of yet another embodiment of the of the handle; 
           [0021]      FIG. 9 b    is a fragmentary, side elevational view of still another embodiment of the handle. 
           [0022]      FIG. 10 a    is a fragmentary, perspective view of a still further embodiment of the handle; 
           [0023]      FIG. 10 b    is a fragmentary, side elevation of the handle shown in  FIG. 10   a;    
           [0024]      FIG. 11  is a fragmentary, perspective view of yet another embodiment of the handle; 
           [0025]      FIG. 12 a    is a fragmentary, perspective view of a quite different embodiment of the handle; 
           [0026]      FIG. 12 b    is a fragmentary, top view of the handle in accordance with the embodiment shown in  FIG. 12   a;    
           [0027]      FIG. 13  is a fragmentary, exploded, perspective view of the handle according to  FIG. 12   a:    
           [0028]      FIG. 14  is a fragmentary, perspective view, partly in cross-section, of the handle according to  FIG. 12   a;    
           [0029]      FIG. 15 a    is a fragmentary, axial cross-section of the handle according to the embodiment of  FIG. 12   a;    
           [0030]      FIG. 15 b    is a fragmentary, axial cross-section of the handle according to the embodiment of  FIG. 15   a;    
           [0031]      FIG. 16 a    is a is a fragmentary, axial cross-section of the handle according to a variant of the embodiment of  FIG. 12 a   ; and 
           [0032]      FIG. 16 b    is a fragmentary, axial cross-section of the handle according to the embodiment of  FIG. 16   a.    
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Referring to  FIGS. 1 to 7  there is shown a lifting implement such as a snow shovel  10  having an elongated handle  12 , a blade  14  at the distal end of the handle  12 , and a grip  20  at the proximal end of the handle  12 . The handle  12 , as will be described may be used with any implement used for lifting or scraping. Examples in addition to snow shovels include round shovels, square shovels, spades, hand plows, hay forks, and the like. 
         [0034]    As shown in  FIGS. 1 and 2 , the handle  12  is a so-called ergonomic handle which allows a user to stand more upright because the lower prehension zone  38  is higher due to the curvature of the handle profile. The handle  12  has the profile of an arc with an chord “z” extending from the proximal end or prehension zone  36  of the lever  18  to the contact tip  37  of the shovel blade  14 . The joint  16  as well as the prehension zone  38  is spaced from the chord “z”. In use this configuration allows any impact energy to be absorbed and converted into rotational energy. This is especially true when the implement is impacting a load or dense material as opposed to mere lifting. 
         [0035]    As shown in  FIGS. 3 and 4 , the handle  12  is separated by a joint  16 . The joint  16  is located a minor distance from the grip  20  at the proximal end of the handle  12 . The portion of the handle between the joint  16  and the grip  20  is identified as lever  18 . The major portion  22  of the handle  12  extends between the distal end and the joint  16 . The grip  20  represents a first prehension zone  36  and the second prehension zone is located at  38  on the major portion  22 . The joint  16  is approximately midway between the first and second prehension zones  36  and  38 . 
         [0036]    The lever  18  is made up of bifurcated arms  18   a  and  18   b  forming a recessed seat  17 . The bifurcated arms  18   a  and  18   b  define hinge barrels  32  at the free ends thereof and are adapted to engage bushings  34  mounted to the major portion  22  coincident with the joint  16 . A bracket  24  projects from the distal end of the major portion  22  towards a position between the bifurcated arms  18   a  and  18   b  within the seat  17 , beyond the axis of joint  16 . A companion bracket  26  projects from the lever  18  over a portion of the seat  17 . 
         [0037]    A coiled spring assembly is best shown in  FIG. 4 . The spring assembly includes a pair of hinge brackets  28   a  and  28   b  extending from either end of a coil spring  28  and fixed to the respective ends thereof. Each of the hinge brackets  28   a  and  28   b  have stub shafts which act as stops as will be described further. The hinge bracket  28   a  is pivotally mounted to the bracket  26  on the lever  18  by means of a pin  30 . The hinge bracket  28   b  is likewise pivotally mounted to the bracket  24  by means of a pin  31 . 
         [0038]    As can be seen, the shovel handle  12  thus includes a shock absorber that allows an angular deflection, during use, of the shovel  10 . Referring to  FIGS. 5 and 6 , the displacement of the joint  16  can be seen in relation to the major portion  22  and the lever  18 .  FIG. 5  shows the handle  12  in a relaxed, neutral position. A triangle is defined that includes a base extending from a point at the first prehension zone  36 , at the hand grip  20 , to a point at the second prehension zone  38  on the major portion  22 . The joint  16  is at the apex of the triangle. In a preferred embodiment, the triangle is an isosceles triangle. The distance between the center of the joint  16  and the base of the triangle, is shown as “x”. Normally, a user would grip the shovel at prehension zone  36 , with one hand, and the prehension zone  38  with the other hand. When the load  15  is engaged on the blade  14 , as shown in  FIG. 1 , the other hand of the user, at prehension zone  38 , will lift the major portion  22  causing the joint  16  to move counterclockwise about the fulcrum presented by the user&#39;s other hand at prehension zone  38 ; while the handle  12  is rotated in a clockwise rotation about the fulcrum presented by the user&#39;s one hand at prehension zone  36 . The torque resulting from this translation movement of the joint  16  compresses the spring  28  as shown in  FIG. 6 . The compression of the spring  28  is limited by the stops on brackets  28   a  and  28   b  as previously described. The maximum translation of the joint  16  relative to the base of the triangle between the first and second prehension zones  36  and  38  is now a distance “y”. 
         [0039]    When using a lifting implement, such as a shovel  10  or hay fork (not shown), shock sometimes caused by striking a rock or ice will be absorbed by the resilient deflection of the translation of the joint  16 . Likewise when displacing a load, such as snow or hay from one location to another by a “heaving” action, the implement  10 , is a free lever operated by the user to enhance the heaving action by multiplying the forces resulting from the energy input provided by the user. In addition to acting as a shock absorber, when the spring  28  is compressed, the stored energy in the spring  28  is released when the load is “heaved” increasing the multiplication of force for the same energy input. 
         [0040]    A shovel  10  would typically lift between 4.5 kg (10 lbs) and 23 kg (50 lbs), but more particularly 16 kg (35 lbs). In the present embodiment the spring was calibrated for a load of 14.5 kg (32 lbs). In this case the spring  28  would reach its maximum compression at 16 kg (35 lbs) with an angular deflection of 20°, displacing the joint  16  from “x” to “y”. The lever  18  from the point on the prehension zone  36  (grip  20 ) to the joint  16  measures 36.80 cm (14.50″). The length of the major portion  22  will vary depending on the type of tool, but in the present embodiment the length was 86.36 cm (34″), the coil spring  28  had a spring index of 8.17; a length of 6.35 cm (2.5″); an internal diameter of 4.52 cm (1.78″); and a wire diameter of 0.55 cm (0.218″). 
         [0041]    It has been found that when the prehension zones  36  and  38  are at an initial angle from one another, as the joint  16  is translated through the work of the implement  10 , the angle of the prehension zones  36  and  38  changes in direct proportion with level of deflection of the handle  12 . The human brain registers this change of angle and sends appropriate signals to the body to “adapt” to the “imminent” change of load as the handle  12  progressively reaches its maximum deflection angle for a given load. 
         [0042]      FIG. 7  shows three shovels  10  stacked for transport or storage. The particular configuration of the seat  17  and the position of the spring assembly  28  between the arms  18   a  and  18   b  allows the stackability of the shovels  10 . 
         [0043]    A second embodiment is shown in  FIG. 8 . In this embodiment similar reference numbers have been used but raised by 100. The bracket  126  extends behind the joint  116 . The spring assembly  128  extends between the bracket  126  and bracket  124  which is fixed to the major portion  122 . The hinge brackets  128   a  mounts a threaded disk  133  that can be translated by means of threads  129  on bracket  128   a  for adjusting the pitch of coil spring  128  and therefore the pre-compression thereof. 
         [0044]      FIGS. 9 a  and 9 b    illustrate two variants of a third embodiment where similar references have been increased by 200. In this embodiment, the spring  228  extends between the respective brackets  224 ,  226  on the front side of the handle  212  but offset of the profile of the handle. In  FIG. 9 a   , an adjustment screw  229  is provided on the bracket  226  to adjust the pitch of the spring  228 . The spring stores energy in tension as it is being extended. 
         [0045]    The embodiment in  FIGS. 10 a  and 10 b    shows the coil spring replaced by a resilient semi-rigid plastic bar  328  pivoted to the brackets  324  and  326 . Arm  318   a  and  318   b  can be provided with a series of bores  318   c  to form pivot barrels to accommodate the adjustment of the length of the plastic bar  328 . Corresponding bores  328   c  on the bar  328  match the bores  318   c . When assembled the pin  330  may be selectively located in any pair of bores  318   c ,  328   c  in order to accommodate different pretension settings. The energy in this embodiment is stored by the deformation of the bar  328 . 
         [0046]    The embodiment in  FIG. 11  utilizes a springboard  428  that is fixed at one end to the brackets  424  and extends in a slot provided in the bracket  426 . A clamp  427  is adjustable on the bracket  426  in order to determine the effective length of the springboard  428  in order to select the pretension setting. Although the springboard  428  will not act in compression, it will store energy when deflected as in the embodiment of  FIG. 10 . 
         [0047]    From the embodiments shown in  FIGS. 10 a   - 11 , it will be evident to the person skilled in the art that the tool handles may also be stackable. 
         [0048]      FIGS. 12 to 16   b , shows embodiments that are conceptually similar to the embodiment shown in  FIG. 11 . The energy is stored by the degree of deflection of a flexible blade  528 . The blade  528  is preferably made of spring steel but may be of another material with similar characteristics. In one example a spring steel section of 3.175 mm (0.125 in.) in thickness by 19.05 mm (0.750 in.) large by 203 mm (8 in.) in length. 
         [0049]      FIGS. 12 to 15   b  illustrate an embodiment that includes a handle  512 , with a grip  520  and arms  518   a  and  518   b . A major portion  522  of the handle  512  pivots relative to the lever  518  at the joint  516 . The major portion  522  including the extension  522   a , is hollow as shown in  FIGS. 13 to 15   b . The bracket  524  is mobile and can slide within the hollow major portion  522 . The bracket  524  includes an elongated rack  544  having gear teeth  544   a.    
         [0050]    The joint  516  includes a pair of barrels  532  formed on the ends of arms  518   a  and  518   b , to accommodate bushings  534  on the major portion extension  522   a . A pivot pin  535  extends through the axis of joint  516 . Knob  540  is journalled on pivot pin  535 . The knob assembly includes a flanged sleeve  541  journalled on the pivot pin  535 . The knob  540  includes a sleeve with geared teeth  540   a , as shown in  FIG. 13 . 
         [0051]    As shown in  FIGS. 15 a  and 15 b   , the flexible blade  528  is slidable in bracket  524  but is fixed, at the other end, to the bracket  526  within the handle  518 . By rotating the knob  540 , the geared sleeve  540   a  will engage the rack  544  to advance the bracket  524  along the flexible blade  528  effectively reducing the active length “y” of the flexible blade  528 . Likewise the mobile arrow  542  mounted to the end of the rack  544  and exposed on the top of the handle  518 , as shown in  FIGS. 12 a  and 12 b   , will display the stiffness of the flexible blade  528  either as “soft”, as shown in  FIG. 15 a   , or as “stiff”, as shown in  FIG. 15   b.    
         [0052]      FIGS. 16 a  and 16 b    show a variant of the embodiment in  FIGS. 15 a  and 15 b   . In this variant, bracket  524  is fixed within the hollow major portion  522 . On the other hand the bracket  526  within the handle  518  is movable along tracks  526   a  and  526   b . The bracket  526  protrudes through the handle  518  and may be engaged manually to adjust the effective length of the flexible blade  528 , and thus the stiffness. In this case the distance “y” remains constant while the distance “x” is variable. According to this variant the position of the bracket  526  shown in  FIG. 16 a    represents the soft condition of the flexible blade  528  while  FIG. 16 b    illustrates the stiffer condition of the blade  528 . 
         [0053]    The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Any modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.