Abstract:
Tool designed to be fixed at the end of the arm of a shovel. The tool includes a curvilinear blade formed by a portion of a straight cylindrical surface whose generating lines extend parallel to an axis of rotation of the tool on the arm. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is a Continuation of International Patent Application No. PCT/FR2003/001758 filed Jun. 12, 2003, and claims priority of French Patent Application No. 02/09305 filed Jul. 23, 2002 and French Patent Application No. 03/03680 filed Mar. 26, 2003. Moreover, the disclosure of International Patent Application No. PCT/FR2003/001758 is expressly incorporated by reference herein in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an excavating tool of the type that is articulated at the end of an hydraulic shovel. 
   2. Background and Material Information 
   In the current state of the art, buckets are used whose width substantially demarcates the width of the trench to be dug. 
   The use of this tool poses problems with respect to emptying it. For example, the soil sticks to the bottom of the bucket and its side walls. Tests have shown that the use of an ejecting paddle not only increases the cost of the bucket, but also does not perform satisfactorily on very loamy soils. 
   Tests have also shown that it is almost impossible to manufacture buckets to dig trenches having a width on the order of 30 centimeters, and capable of digging down to a depth of up to about one meter. Indeed, in order to accomplish this, one needs to manufacture a very elongated bucket, and the surface of the lateral sides are large for a relatively small mass of earth: the forces due to friction are substantial and emptying the bucket is almost impossible. 
   The document U.S. Pat. No. 3,032,900 describes a tool which has concentric blades connected to a bottom by one of their ends, and to a sheet which extends in the median plane of the tool by one of their edges. 
   This tool does not perform satisfactorily because the earth sticks to the bottom and each side of the sheet. 
   SUMMARY OF THE INVENTION 
   The instant invention, which remedies these disadvantages, is characterized in that the tool is constituted by a curvilinear blade affixed by its rear surface to a substantially vertical sheet, connected to the shovel&#39;s arm in the usual way. 
   This blade is formed by a portion of a straight cylindrical surface, the generating lines of which extend substantially parallel to the articulation axis of the tool with respect to the shovel&#39;s arm. 
   According to one characteristic of the invention, the blade has openings so as to reduce the contacts between the soil and the tool. 
   The tool of the present invention, which remedies these disadvantages, can have a plurality of curvilinear blades and is characterized in that the curvilinear blades are angularly offset so that the distance between the lower ends of two adjacent blades is greater than that separating the upper ends of the blades. 
   The distance separating the articulation axis of the tool on the shovel&#39;s arm from the lower end of each blade can increase from the first to the last, whereby the first blade is the one that first penetrates into the earth. 
   The invention also provides for a tool that is attachable to an end of an arm of a shovel, wherein the tool comprises at least one curvilinear blade. 
   The at least one blade may comprise a straight cylindrical surface, whereby lines generating the cylindrical surface extend parallel to a rotation axis of the tool on the arm. The at least one blade may comprise openings. The at least one blade may comprise a plurality of blades angularly offset from one another. The at least one blade may comprise two adjacent blades, wherein a distance separating upper ends of the two adjacent blades is smaller than a distance separating lower ends of the two adjacent blades. 
   The at least one blade may comprise a plurality of blades angularly offset from one another and wherein a distance between an articulation axis of the tool and a lower end of each of the plurality of blades increases from a first of the plurality of the blades to a last of the plurality of the blades. During excavation, the first blade may be configured to penetrate into earth before the last blade. 
   The at least one blade may be removably mounted to the tool. The tool may further comprise a sheet member having at least one base portion, wherein the sheet member is arranged to couple the at least one blade to a cap portion of the tool. The sheet member may comprise a concave surface which corresponds to a convex surface of the at least one blade. 
   The tool may further comprise a sheet member and an arrangement for fixing the at least one blade to the sheet member. 
   The at least one blade may comprise first and second blades and wherein the tool further comprises a sheet member that is configured to connect each of the first and second blades to a cap portion of the tool. 
   The at least one blade may comprise first and second removably mounted blades and wherein the tool further comprises a sheet member that is configured to connect each of the first and second removably mounted blades to a cap portion of the tool. 
   The invention also provides for a tool that is attachable to an end of an arm of a shovel, wherein the tool comprises a cap portion arranged to pivot with respect to the end of the arm, at least one blade member comprising a convex rear surface, a concave surface, and a soil engaging end, and a sheet member comprising a first edge connected to a surface of the cap portion and a second edge connected to the convex rear surface of the at least one blade. 
   A thickness of the sheet member may be less than a width of the at least one blade member. The at least one blade member may comprise openings. The first edge may be connected to a central portion of the surface of the cap portion and the second edge may be connected to a central portion of the convex rear surface of the at least one blade member. 
   The at least one blade member may comprise two adjacent blade members, wherein a distance separating upper ends of the two adjacent blade members is smaller than a distance separating lower ends of the two adjacent blade members. The at least one blade member may be removably mounted to the sheet member. The second edge of the sheet member may comprise a concave surface which corresponds to the convex rear surface of the at least one blade member. The at least one blade member may comprise first and second removably mounted blade members and wherein the sheet member connects each of the first and second removably mounted blades to the cap portion of the tool. 
   The invention also provides for an excavating tool comprising a cap portion comprising a mechanism for pivotally mounting the excavating tool to an end of an arm, at least one blade member comprising a convex rear surface, a concave surface, and a soil engaging end, and a sheet member comprising a first edge connected to a central portion of a surface of the cap portion and a second concave edge connected to a central portion of the convex rear surface of the at least one blade. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     Other characteristics of the invention will be better understood from the following description, with reference to the annexed drawings provided by way of example only, wherein: 
       FIG. 1  shows a side view of one embodiment of a tool according to the invention; 
       FIG. 2  shows a rear view of  FIG. 1 ; 
       FIG. 3  shows a side view of another embodiment of a tool according to the invention; 
       FIG. 4  is a rear view of  FIG. 3 ; 
       FIGS. 5-8  show the embodiment of  FIG. 3  in use; 
       FIG. 9  shows an alternative embodiment similar to  FIG. 8 ; 
       FIG. 10  shows another embodiment of the tool and which is similar to the one of  FIG. 3 ; 
       FIG. 11  shows a cross-sectional view, straightened out, along the line XI-XI of  FIG. 10 ; 
       FIG. 12  shows a side view showing a blade used in the embodiment of  FIG. 10 ; 
       FIG. 13  shows a rear view of  FIG. 12 ; and 
       FIGS. 14-16  are side views showing how a tool with one blade can be transformed into a tool with several blades. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The tool of the invention is made of a curvilinear blade  1  that is borne by a central sheet  2  arranged behind the blade  1 . The sheet  2  is affixed to a regular cap  3  for fixing the tool to the end of a shovel&#39;s arm  4  by way of a shaft  5 . In a known fashion, there is provided a cylinder whose stick  6  allows the tool to be pivoted about the axis of the shaft  5 . 
   The blade  1  is constituted by a portion of a straight cylindrical surface whose generating lines extend parallel to the axis of the shaft  5 . 
   In general, the fixing of the tool can be accomplished by way of a quick connector such as the one described in the French Patent No. 2 785 951. 
   The blade  1  can have openings  7  which function to reduce the surface of the blade  1  that comes into contact with the soil. 
   According to the embodiment shown in  FIG. 3 , the tool has a plurality of blades  1  which are angularly offset. In this regard, the distance “d” which separates the upper ends of two adjacent blades  1  is smaller than the distance “D” which separates the lower ends of the blades  1 . 
   It should be noted that the portion of the surface of the sheet  2  that extends behind the blades  1  is insignificant. 
   The blades  1  are preferably identical to each other, and their width can define the width of the trench to be dug. 
   In addition to the blades  1  being angularly offset, the distance between an axis of the shaft  5  and an end of a corresponding blade can increase in the direction of rotation of the tool during penetration into the ground S (counterclockwise direction shown in  FIGS. 5-7 ). 
     FIG. 8  shows the position of the tool after it has come out from the trench. When the ground is very sandy, the dug soil may partially crumble laterally. In this case, and as is seen in  FIG. 9 , retaining edges  1   a  are provided on each blade  1 . The surface of these edges  1   a  is very small in order not to create ill-timed friction which could have a negative effect on the penetration of the tool into the ground S and the removal of the dug out soil. 
   According to another characteristic of the invention, the blades  9  can be removable. 
   Along these lines and according to another embodiment, the sheet  2  has bases  8 . The corresponding blade is fixed on each base  8  by any appropriate arrangement and each base  8  is configured to fit the convex surface of the blade, which is preferably a straight cylindrical surface with a circular directing line. 
   As seen in  FIGS. 10-13 , each blade has a fixing arrangement. According to this embodiment, the convex surface of each blade  9  has a yoke  10  arranged on its lower end and a cap  11  arranged on its upper end. The wings of the sheet  2  of the tool can be inserted between the parts  10  and  11 . 
   The blade  9  is retained in the position of  FIG. 10  via a pin  12 . In this regard, holes  13  are provided for this purpose on the sheet  2 . In order to mount the blade  9 , it is first engaged on the sheet  2 , then slid downward so that the yoke  10  is located above the lower end of the base  8 . While keeping the blade  9  pressed against the base  8 , it is slid upward so that the lower end of the base  8  penetrates into the yoke  10  and, finally, the pin  12  which retains the blade  9  is positioned in the hole. The disassembling can be accomplished in reverse order. 
   It should be noted that the invention contemplates that the blades of the same tool can vary as much in width as in length. 
     FIG. 14  shows another embodiment of the tool of  FIG. 1  wherein a sheet  2   a  is shaped to cooperate with the sheet  14  of a blade  15  (see  FIG. 15 ) in order to make a two-blade tool from a single-blade tool, as shown in  FIG. 16 . 
   The fixing of the blade  15  of  FIG. 15  is accomplished, for example, by way of two plates  16 , arranged on each side of the sheets  2  and  14 , and retained by bolts. The bolts are illustrated as axes  17 . It should be noted that the sheet  14  can also be shaped so as to enable the fixing of a third blade. 
   In the examples described and shown, the sheets are formed as portions of cylindrical surfaces with a circular directing line. 
   It is possible, however, within the scope of the invention, to make curvilinear blades wherein the directing line no longer has the appearance of a continuous curve but rather that of a polygonal line. For example, a polygonal line that can fit in a circle arc can be utilized. 
   Along the same lines, the curvilinear blade of the invention can be obtained by folding a flat blade in the same direction, whereby the various folds form a relatively small angle with the articulation axis of the tool with respect to the arm.