Abstract:
The present invention teaches a shovel having a scoop with a bottom perforated by apertures and a movable sifting plate held in one of a plurality of possible positions by means of a retainer plate. The sifting plate may have apertures which do not overlap the apertures of the scoop in a first position, thus keeping the bottom of the shovel scoop closed for use as a shovel. In a second position, the sifting plate apertures may overlap the apertures of the scoop bottom so as to provide a degree of sifting ability. Either set of apertures may have a screen thereacross. The retaining plate may be biased by a spring so as to hold the sifting plate in position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the priority and benefit of U.S. Provisional Application No. 60/584,973 filed Jul. 1, 2004 in the name of the same inventor, Charles E. Gorbet, and entitled SHIVEL, the disclosure of which is incorporated herein by this reference thereto. 

   FIELD OF THE INVENTION 
   This invention relates generally to shovels and specifically to adjustable shovels. 
   Statement Regarding Federally Funded Research 
   This invention was not made under contract with an agency of the US Government, nor by any agency of the US Government. 
   BACKGROUND OF THE INVENTION 
   One problem encountered during shoveling is that it may be necessary to pick up a discrete object from a surface composed of smaller particulate matter. For example, when leveling sand for a layer of “pavers” (blocks of masonry used to construct a stone surface), a shovel user may notice a pebble or leaf that has blown onto the sand. After a windstorm, a large number of such minor bits of debris may be present. However, when attempting to shovel up such items, the user inevitably is left with a large quantity of the sand which is scooped up into the shovel scoop with the pebble or leaf. 
   A number of similar problems occur. Cleaning a beach or child&#39;s sand box, for example, may entail picking up broken glass or toys from among sand, preferably without the large quantity of sand which is inevitably scooped up with it. Cleaning a pet&#39;s “litter box” means picking up particularly noxious items from a matrix of small particles of litter. Picking up larger items from a bed of leaves, gravel or moss may pose similar problems. 
   One solution is a “sifter” type of filter device. A screen may be used to allow smaller particles to fall away while the items sought for removal are removed. This may be practical for certain limited applications and cases in which the user is willing to have a dedicated device having no use but filtering. However, such devices have a substantial disadvantage in that they are not useful for moving the filtered particles if that is needed, cannot be used to shovel and so on. 
   It would be advantageous to provide a device usable as both a shovel and a filter. 
   SUMMARY OF THE INVENTION 
   General Summary 
   The present invention teaches a shovel having a scoop with a bottom perforated by apertures and a movable sifting plate held in one of a plurality of possible positions by means of a retainer plate. The sifting plate may have apertures which do not overlap the apertures of the scoop in a first position, thus keeping the bottom of the shovel scoop closed for use as a shovel. In a second position, the sifting plate apertures may overlap the apertures of the scoop bottom so as to provide a degree of sifting ability. Either set of apertures may have a screen thereacross. 
   The retaining plate may be biased by a spring so as to hold the sifting plate in position. The retaining plate spring may sit on a post projecting from the retaining plate, under pressure from an arm projecting from the scoop. A tab, pin, or other projection from the retaining plate may pass through the sifting plate at a positioning slot and into a retaining slot in the scoop, thereby preventing motion of the sifting plate unless the retaining plate is moved, against the urging of the spring, into a position at which the tab does not project through the positioning slot into the retaining slot. 
   Summary in Reference to Claims 
   It is therefore a first aspect, advantage, objective and embodiment of the invention to provide a shovel comprising:
         a shovel having a scoop portion and a shovel handle portion;   the scoop portion having a bottom, a leading edge, and a side, the bottom having at least one first sifting opening therethrough, the side having at least one retaining aperture thereinto;   a sifting plate having at least one second sifting opening therethrough and a plurality of positioning apertures therethrough; and   a retaining plate having a tab dimensioned and configured to pass through at least one of the positioning apertures and into the retaining aperture in a first position, the tab not passing into the retaining aperture in a second position, the retaining plate having a spring urging it into the first position.       

   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, further comprising:
         a retaining plate handle attached to the retaining plate, the retaining plate handle dimensioned and configured to provide a secure hand grip when the retaining plate is pulled against the spring into the second position.       

   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, further comprising:
         at least one retaining arm projecting upward from the scoop side,   at least one post projecting upward from the retaining plate,   the spring disposed under compression on the post and between the retaining arm and the retaining plate.       

   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, wherein the retaining plate further comprises: a slanted side dimensioned and configured to engage the scoop side. 
   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, further comprising:
         at least one sifting plate retainer projecting upwards from the scoop and cantilevered over at least one edge of the sifting plate.       

   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel wherein the first and second sifting openings comprise rectangular apertures arranged with the long axis of the rectangle parallel to the leading edge. 
   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, wherein the first and second sifting openings are identical in dimension and configuration. 
   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel wherein a first of the plurality of positioning apertures through the sifting plate is positioned so that when the tab of the retaining plate passes therethrough and into the retaining aperture, the sifting plate is positioned in a first sifting plate position wherein the first and second sifting openings do not overlap and the shovel scoop bottom is entirely closed. 
   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, wherein a second of the plurality of positioning apertures through the sifting plate is positioned so that when the tab of the retaining plate passes therethrough and into the retaining aperture, the sifting plate is positioned in a second sifting plate position wherein the first and second sifting openings overlap by a first percentage of the surface area of the scoop bottom. 
   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel, wherein a third of the plurality of positioning apertures through the sifting plate is positioned so that when the tab of the retaining plate passes therethrough and into the retaining aperture, the sifting plate is positioned in a third sifting plate position wherein the first and second sifting openings overlap by a second percentage of the surface area of the scoop bottom. 
   It is therefore another aspect, advantage, objective and embodiment of the invention to provide a shovel wherein a screen is positioned across and attached to one member selected from the group consisting of: first sifting opening, second sifting opening, and combinations thereof. 
   It is therefore yet another aspect, advantage, objective and embodiment of the invention to provide:
         a shovel having a scoop portion and a shovel handle portion;   the scoop portion having a bottom, a leading edge, and a side, the bottom having at least one first sifting opening therethrough, the side having a plurality of retaining apertures;   a sifting plate having at least one second sifting opening therethrough and at least one positioning apertures therethrough; and   a retaining plate having a tab dimensioned and configured to pass through the positioning aperture and into at least one of the retaining aperture in a first position, the tab not passing into the retaining aperture in a second position, the retaining plate having a spring urging it into the first position.       

   It is therefore yet another aspect, advantage, objective and embodiment of the invention to provide a shovel comprising:
         a shovel having a scoop portion and a shovel handle portion;   the scoop portion having a bottom, a leading edge, and a side, the bottom having at least one first sifting opening therethrough;   a sifting plate having at least one second sifting opening therethrough; and   a retainer having a first position, the retainer dimensioned and configured to prevent motion of the sifting plate when in a first position, the retainer having a spring urging it into the first position.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partially exploded near-frontal perspective view of the first embodiment of the invention. 
       FIG. 1   a  is a partial cross-sectional view of the retaining plate spring mechanism of the invention. 
       FIG. 2  is a frontal view of the scoop bottom, scoop sides, sifting plate and sifting plate retainers of the invention. 
       FIG. 3  is a side view of a second embodiment of the invention in which the retaining slots do not pass entirely through the sides of the scoop and the retainer plate sits entirely within the interior of the scoop. 
       FIG. 4  is a planform view of a third sifting plate embodiment of the invention. 
       FIG. 5  is a side view of a scoop of a fourth embodiment of the invention, in which there are multiple retaining slots to allow positioning of the retaining plate. 
       FIG. 6  is a planform view of a fifth scoop bottom according to the invention. 
   

   INDEX TO THE REFERENCE NUMERALS 
   
       
       First embodiment  10   
       Scoop  12   
       Retaining plate  14   
       Retaining plate handle  16   
       Plate body  20   
       Post  22   
       Slanted side  24   
       Tab  26   
       Retaining arms  28   
       Retaining slots  30   
       First side  32   
       Second side  34   
       Leading edge  36   
       Back side  38   
       Bottom  40   
       Retaining clips  42 ,  42   a    
       Retaining spring  44   
       Sliding sifting plate  46   
       Scoop handle  48   
       Sifting plate upper portion  50   
       Extension  52   
       Positioning slots  54   a, b, c, d    
       Sifting openings  56   
       Blocked areas  58   
       Retaining slots  60   a, b, c, d    
       Sifting openings  66   
       Blocked areas  68   
     
  
   DETAILED DESCRIPTION 
     FIG. 1  is a partially exploded near-frontal perspective view of the first embodiment of the invention, one of the presently preferred embodiments and best mode presently contemplated for carrying out the invention.  FIG. 1   a  is a partial cross-sectional view of the retaining plate spring mechanism of the invention. First embodiment  10  has scoop  12  and retaining plate  14 , which comprise two of the three major components of the invention. Retaining plate handle  16  may be used to pull retaining plate  14  away from scoop  12  in order to allow adjustment of the degree of blocking versus filtering area of the scoop  12 . Plate body  20  may be dimensioned and configured in much the same shape as the back of the scoop  12  or the cross-section of the scoop  12 . Post  22  may sit near (or directly above) slanted side  24  having tab  26  projecting therefrom. Retaining arm  28  may project from scoop  12  above or near retaining slots  30  on first side  32  and second side  34 . Retaining slots  30  may pass all the way through sides  32 ,  34 , or may in embodiments merely pass into the scoop at some point, still serving the same function. (In the strongly frontal oblique view of  FIG. 1 , the retaining slots may be foreshortened.) Sides  32 ,  34  may be angled at an angle such as 45 degrees, within a wide range of plus or minus 20 degrees or more. In the presently preferred embodiment and best mode now contemplated, the angle is approximately 45 to 55 degrees. One factor to consider is that the angle should promote smooth positive motion and locking by the tab  26  through the apertures on the plate and scoop. Note that slanted side  24  may be dimensioned and configured to match the sides  32 ,  34 , for example by having the same angles and lengths or complementary angles and lengths. 
   Leading edge  36  may be a normal shovel blade edge, useful for either scooping or shoveling. Back side  38  may comprise the back side of the scoop  12  and may prevent materials scooped or shoveled from falling off of the back end of the scoop  12 . 
   Bottom  40  is of particular interest. In addition to retaining clips  42 , it may have a series of apertures (better seen in  FIG. 6  as they are foreshortened by perspective in  FIG. 1 ) therethrough. These apertures will allow the scoop  12  to function as a filter when they are not completely occluded. Retainer clips  42  may be punched upwards from the material of the scoop bottom  40  and shaped to suit their function, or may be additional projections from the scoop bottom  40 . 
   Retaining spring  44  sits on post  22  in this embodiment, but may be otherwise secured in alternative embodiments. It sits under compression between retaining plate  20  and arm  28 , thus urging retaining plate  20  downwards. It will be appreciated that spring  44  may advantageously be situated close to tab  26  so as to directly urge tab  26  through slots on the other parts of the device. 
     FIG. 2  is a frontal view of the scoop bottom, scoop sides, sifting plate and sifting plate retainers of the invention. Retaining clips  42  and  42   a  may be seen to retain sliding sifting plate  46  securely on at least one surface of scoop bottom  40 . Sifting plate  46  may thus slide along the front to back axis of scoop  12  but not lift out from scoop  12  nor slide sideways to significant degrees. 
   In embodiments, retaining clips  42  may be oriented in a different direction, so that sifting plate  46  may slide in a different direction but is still retained securely against scoop  12  bottom  40 . 
     FIG. 3  is a side view of a second embodiment of the invention in which the retaining slots do not pass entirely through the sides of the scoop and the retainer plate sits entirely within the interior of the scoop, invisible from the side. Side  32  thus hides the retainer plate. 
   Scoop handle  48  may be a one hand handle for a short scoop such as may advantageously be used for pet litter boxes, or may be longer for gardening work, or may be extensible, removable, etc. 
     FIG. 4  is a planform view of a third sifting plate embodiment of the invention. Sifting plate upper portion  50  may have projecting therefrom extension  52  which has thereon positioning slots  54   a, b, c, d.    
   Tab  24  ( FIG. 1 ) may pass through one selected positioning slot  54   a  when the sifting plate  46  is in a first position, and may pass through a different selected positioning slot  54   b  when the sifting plate  46  is in a second position, through a third positioning slot  54   c  in a third position, and so on. 
   Sifting openings  56  and blocked areas  58  may be seen to cover the portion of sifting plate  46  which covers portions of scoop  12  bottom  40 . Thus when the sifting plate  46  is in a first position, the blocking areas  58  may cover a first percentage of the apertures through the bottom  40  of scoop  12 . When the sifting plate  46  is in a second position, the blocking areas  58  may cover a second percentage of the apertures through the bottom  40  of scoop  12 . When the sifting plate  46  is in a third position, the blocking areas  58  may cover a third percentage of the apertures through the bottom  40  of scoop  12 . One of the percentages covered may be 100% in the presently preferred embodiment and best mode presently contemplated for carrying out the invention, thus allowing the bottom  40  to be closed, allowing no sifting action but allowing use as a spade or shovel or traditional scoop. 
     FIG. 5  is a side view of a scoop of a fourth embodiment of the invention in which there are multiple retaining slots to allow positioning of the retaining plate. Thus in this embodiment, there are multiple slots through the scoop  12  sides ( 32 ,  34 ) in order to allow a plurality of different positions of the sliding sifting plate  46 .  FIG. 6  is a planform view of a fifth scoop bottom according to the invention. Sifting openings  66  and blocked areas  68  may be the same width as the sifting openings  56  and blocked areas  58  of the sliding sifting plate  46 , or they may be different widths, or even different lengths. 
   Retaining slots  60   a, b, c, d  pass entirely through the side  32  and allow multiple sift plate positions even in alternative embodiments in which there is only one positioning slot  54   a  on the sliding sift plate. However, in the best mode now contemplated, there may be multiple slots on both scoop and plate, so that a wide variety of different positions may be attained. 
   As an example, consider a simple embodiment in which apertures and blocking areas have the same width (in alternative and more complex embodiments, apertures and blocking areas may have differing widths, or the apertures/blocks of the scoop bottom may be of different widths than those of the sifting plate). If each of retaining slots  60   a, b, c, d  is positioned at a distance from the next retaining slot equivalent to 25% of the width of the apertures/blocks, then merely by using the retaining slots, a user may select degrees of opening (or alternatively, degrees of occlusion) of the apertures corresponding to 0, 25%, 50%, and 75% of the width of the openings. Now if the positioning slots  54   a, b, c, d  having mutual distances of multiples of 5% of the aperture/block width, they may be used to achieve opening percentages of 0%, 5%, 10% and 15%, but also, be using both sets of apertures, a total exemplary selection of opening distances of 0%, 5%, 10%, 15%, 25%, 30%, 35%, 40%, 50%, 55%, 60%, 65%, 75%, 80%, 85% and 90% of the total widths. This simplified example misses some opening widths (100%, 95%, 70%, 45%, and 20%) but it will be appreciated that merely adding one more slot to either scoop or sifting plate will remedy this, and thus any size of opening may be secured, as well as an extremely wide variety of percentages of the opening. 
   It is anticipated that there will be little need for screens on the apertures of either shovel scoop or sliding sifting plate, due to the extreme flexibility in choosing aperture sizes which the design allows, however, screens may be added across the apertures of either scoop bottom or sifting plate in embodiments. 
   The disclosure is provided to allow practice of the invention by those skilled in the art without undue experimentation, including the best mode presently contemplated and the presently preferred embodiment. Nothing in this disclosure is to be taken to limit the scope of the invention, which is susceptible to numerous alterations, equivalents and substitutions without departing from the scope and spirit of the invention. The scope of the invention is to be understood from the appended claims.