Patent Publication Number: US-2023140211-A1

Title: Sharpening Sheath Adapted To Receive A Knife, And Combination of Such A Sheath And A Knife

Description:
TECHNICAL FIELD 
     The present invention relates to the field of blade sharpeners and concerns in particular scissor and kitchen knife blade sheaths incorporating a sharpener. 
     STATE OF THE ART 
     It is known different manual systems of sharpening of kitchen knives. The first knife sharpeners were simple stones or guns requiring from the user a certain mastery and dexterity of the gesture allowing the sharpening of the blade, and requiring a knowledge of the sharpening angles. 
     It is known that there are more complex knife sharpeners that try to simplify and facilitate their use for a neophyte user by allowing a greater precision of sharpening. However, these systems have the disadvantage of sharpening only one side of the blade at a time, or of causing premature wear of the blade. 
     As an example, it is known from the document FR2576537, a sharpening scabbard associated with a knife which allows to simplify the sharpening operation. 
     However, such a device has the disadvantage that it causes premature wear of the blade and/or is highly dependent on the blade height, so that such a sheath is not suitable for holding knives with very different blade heights. 
     SUMMARY OF THE INVENTION 
     The purpose of the invention is to propose a knife sharpening scabbard with a precise guidance allowing the user to have a maximum guarantee on the quality of his sharpening angles and on the sharpening efficiency. Another aim of the invention is to provide a knife sharpening scabbard which guarantees a good sharpening quality on knives regardless of the blade height of the knives. 
     To this end, the invention has as its object a sharpening sheath, adapted to receive a knife to be sharpened or stored, comprising a cavity intended to receive a blade, an access opening at one end of the cavity, the sheath comprising, preferably in the vicinity of the access opening an upper part provided with a guiding device for the back of the blade and a lower part comprising a sharpening device on which the cutting edge of the blade is intended to be applied when inserting or extracting the blade in the sheath, characterized in that the guide device comprises a V-shaped groove and in that the sharpening device comprises two sharpening elements arranged in a V-shape opposite the groove of the guide device, the sharpening device being movably mounted with respect to the guide device and being returned by return means towards the guide device. 
     Thus, the V-shaped sharpening elements and the V-groove in combination form a diamond-shaped opening into which the end of the blade is inserted when the knife is stored in the sheath. 
     Such a feature ensures both good guide and blade centering on both sharpening elements for very different blade profiles and heights. Advantageously, this facing feature allows the sharpening angle to remain symmetrical and constant throughout the sharpening process, i.e. during the friction of the blade against the sharpening elements. 
     In particular, such a technical solution makes it possible to obtain a regular and constant sharpening of the blade, thanks to the perfect inclination and centering of the blade on the two sharpening elements and the substantially constant pressure exerted by the two sharpening elements on the cutting edge under the effect of the return means. 
     The device may further have one or more of the following features, taken alone or in combination. 
     According to an advantageous feature of the invention, the sharpening device is attached to an arm rotatably mounted inside the sheath. 
     The advantage of such a construction is that it is simple and economical to make and allows for both a good hold and a large amount of travel of the sharpening device along the cutting edge of the blade. 
     According to an advantageous feature of the invention, the two sharpening elements are arranged in two offset planes parallel to each other and perpendicular to the longitudinal axis of the sheath. 
     This arrangement reduces the width of the grinding device. 
     According to an advantageous feature of the invention, the arm has a first longitudinal end that is pivotally mounted on a base. 
     According to an advantageous feature of the invention, the return means comprise a return spring, advantageously helical, interposed between the arm and a base. 
     Such a construction has the advantage of being simple and economical to realize. 
     According to an advantageous feature of the invention, the sharpening elements are arranged in a sharpening device which is pivotally mounted at a second longitudinal end of the arm. 
     Such a feature optimizes blade sharpening when the blade has a pronounced curvature, by allowing the sharpening device to pivot to follow a curved profile of the blade. 
     According to an advantageous feature of the invention, the arm is pivotally mounted on the quill about a first pivot axis and the sharpening device is pivotally mounted on the arm about a second pivot axis, the first and second pivot axes being parallel. 
     According to an advantageous feature of the invention, the sharpening device is disposed adjacent to the access opening. 
     Such a feature allows the blade to be sharpened along substantially the entire length that is inserted into the sheath. 
     According to an advantageous feature of the invention, the sheath comprises a base and a casing removably mounted on the base. 
     This feature simplifies the cleaning of the interior of the sheath. 
     The invention also relates to a combination of a sharpening sheath as previously described and a knife to be sharpened or stored in said sheath. 
     According to an advantageous feature of the invention, the sheath comprises a locking element cooperating with a safety notch provided on the back of the blade to longitudinally immobilize the knife in the sheath when the knife occupies a storage position in which the blade is inserted into the sheath. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The purposes, aspects and advantages of this invention, according to the description given below of a particular embodiment of the invention presented by way of non-limiting example, will be better understood by referring to the attached drawings in which: 
         FIG.  1    is a perspective view of a sheath and a knife according to a particular embodiment of the invention; the knife being represented on the outside of the sheath. 
         FIG.  2    is an exploded perspective view of the sheath of  FIG.  1   ; 
         FIG.  3    is a perspective view of the sheath of  FIG.  1    with the knife introduced into the sheath, the sheath being in this figure shown without its outer shell in order to allow visual access to the sheath mechanism; 
         FIG.  4    is a longitudinal sectional view of the sheath and knife in the position shown in  FIG.  3   ; 
         FIG.  5    is a bottom view of the removable sheath shell; 
         FIG.  6    is another perspective view of the sheath of  FIG.  1    lacking its knife; 
         FIG.  7    is a cross-sectional view according to line VII-VII of  FIG.  4   ; 
         FIG.  8    is an exploded perspective view of the sharpening device in the sheath. 
     
    
    
     Only those elements required in order to understand the invention have been depicted. In order to facilitate interpretation of the drawings, the same elements are labeled with the same references across all the figures. 
     Note that in this document, the terms “horizontal”, “vertical”, “lower”, “upper”, “top”, “bottom”, “front”, “back”, “longitudinal”, “transverse”, used to describe the sharpener refer to the sharpener in use, when it is lying flat on its base. 
       FIGS.  1 ,  3  and  4    show a sharpening sheath  1  and a kitchen knife  2  comprising a blade  20  intended to be stored in the sheath  1 , the knife  2  classically comprising a handle  21  which protrudes out of the sheath  1  when the blade  20  is stored in the sheath  1 . 
     According to  FIG.  2   , the sheath  1  comprises a base  3  and a casing  4  fixed on each other, and advantageously made of plastic material. The base  3  and the casing  4  have an elongated shape defining a cavity  40  intended to receive the blade  20  of the knife  2  for storage, the sheath  1  having a rear end provided with an access opening  10  through which the blade  20  of the knife  2  can be introduced into the cavity  40 . Upstream of the access opening  10 , the casing  4  has a guide skirt  41  which has walls that converge in the direction of the access opening  10  and allow the tip of the blade  20  of the knife  1  to be guided towards the access opening  10 . 
     The base  3  comprises a base  30  comprising a lower face intended to rest flat on a support and comprises a front end formed by a grid  31  which extends upwards from the base  30  forming an angle of the order of 65° with respect to the lower face of the base  30 , the grid  31  closing the front end of the sheath  1  and advantageously being obtained by molding with the base  30 . 
     The opening  4  is advantageously removably fixed to the base  3  and has an inverted U-shaped cross-section, visible in  FIG.  5   , comprising, at each of its ends, a rib  42  engaging in a guide groove  32  provided longitudinally on each side of the base  30  of the base  3 . 
     In accordance with  FIGS.  3  and  4   , the sheath  1  has a device for guiding the upper part of the blade  20  of the knife  2 , also referred to as the back of the blade  20 , comprising a guide piece  5  fixed inside the sheath  4 , at its curved part defining the top of the sheath  4 , the guide piece  5  extending in the longitudinal axis of the sheath  1  from the open end of the sheath  1  to the grid  31  defining the front end of the sheath  1 . 
     Preferably, the guide piece  5  comprises an opening  51  in the vicinity of its front end, in which a hook  45  carried by the opening  4 , visible in  FIGS.  2  and  4   , engages, the front end of the guide piece  5  comprising a head  52  which projects upwards and which engages in a suitable cut-out  44  provided at the front end of the opening  4 . 
     The insertion of the hook  45  into the opening  51  and the engagement of the head  52  in the indentation  44  allow the front end of the guide piece  5  to be removably fixed to the front end of the opening  4 . 
     The guide piece  5  is advantageously fixed to the rear end of the opening  4  by clipping, the rear end of the guide piece  5  comprising a centering ring  50  that resiliently engages between two locking clips  43  projecting from the edges of the access opening  10  of the sheath  1 . 
     As can be seen in  FIG.  2   , the head  52  of the guide piece  5  engages longitudinally in a notch  33  provided at the upper end of the grid  31  when the envelope  4  is put in place on the base  3 , the head  52  having a lower face comprising a groove  53  in which a locking tab  34  disposed at the base of the notch  33  resiliently engages, making it possible to maintain the envelope  4  in position on the base  3 . 
     In accordance with  FIGS.  5  and  6   , the centering ring  50  has an inverted V-shaped groove  54  providing centering of the back in the blade  20  relative to the sheath  4  when the blade  20  is inserted into the sheath  1 . 
     The sheath  1  comprises, opposite the centering ring  50 , a sharpening device  6  advantageously carried by an arm  7  pivotally mounted on the base  3 , the sharpening device  6  being returned in the direction of the centering ring  50  by a return spring  8  acting on the arm  7 . Preferably, the arm  7  is movable in the plane of the blade  20  between a high position where the return spring  8  is extended to its maximum and a low position where the return spring  8  is compressed to its maximum. 
     According to  FIGS.  2  and  3   , the arm  7  has a first end, called the front end, pivotally mounted in the vicinity of the front end of the base  3 , by means of a first axis  71  extending perpendicular to the longitudinal direction of the base  3 . In the particular embodiment shown in the figures, the first axis  71  is supported by two lateral partitions  35  extending vertically on either side of the front end of the arm  7 , these lateral partitions  35  contributing to the rigidity of the connection between the base  30  and the grid  31 . 
     The arm  7  has a second end, the so-called rear end, on which the grinding device  6  is preferably pivotally mounted about a second axis  72  extending parallel to the first axis  71 , the device being able to pivot relative to the arm  7  over an angular range of at least 15° and preferably about 30°. 
     In the example shown in the figures, the arm  7  comprises two lateral lugs  73  which project towards the rear of the arm  7  and between which the sharpening device  6  is arranged, the second axis  72  being advantageously formed by cylindrical pins of circular cross-section which project laterally from the sharpening device  6  and which are engaged in circular openings provided in the lateral lugs  73 . 
     As can be seen more precisely in  FIG.  8   , the sharpening device  6  comprises a U-shaped body supporting two sharpening elements  60  arranged so as to form a V in a plane of projection perpendicular to the longitudinal axis of the sheath  1 , i.e. when the sharpening device  6  is seen along the direction of introduction of the blade  20  into the access opening  10  of the sheath  1 , the two sharpening elements  60  being staggered on the longitudinal axis of the sheath  1  and each extending in a plane perpendicular to the longitudinal axis. 
     The two grinding elements  60 , advantageously constituted by two cylinders of ceramic material, are disposed in two housings  61  arranged to hold two grinding elements  60  in the V-shaped arrangement, the grinding device  6  comprising a slot  63 , arranged between the two U-shaped legs, providing access to the space between the two grinding elements  60 . The two sharpening elements  60  are immobilized by friction inside their housing  61  thanks to the support of a part of the body of the sharpening device  6 , not visible on the figures, against the end of the sharpening element  60 . Thus, the sharpening elements  60  do not rotate in their housing  61 , or only slightly, when they are subjected to the friction of the blade  20  during the insertion or extraction of the latter in the sheath  1 . 
     In the particular embodiment shown in the figures, the return spring  8  is a coil spring arranged between the base  3  and the underside of the arm  7 , near the rear end of the arm  7 . In order to ensure that the return spring  8  is held between the arm  7  and the base  3 , the base  3  comprises a cup  36  for holding the lower end of the return spring  8  and the lower face of the arm  7  comprises a cup  74  for holding the upper end of the return spring  8 , the cup  74  facing the cup  36  when the arm  7  is brought towards the base  3 . 
     Advantageously, the back of the blade  20  of the knife  2  has a safety notch  22 , preferably arranged in the vicinity of the handle  21  of the knife  2 , in which a locking element  55 , constituted by the bottom of the groove  54 , engages when the entire blade  20  is inserted through the sheath  1 , as illustrated in  FIGS.  3  and  4   . Such insertion of the locking element  55  into the safety notch  22 , under the effect of the thrust of the return spring  8  on the arm  7 , allows the knife  2  to be immobilized longitudinally in the sheath  1  in a storage position. 
     The operation of the Sharpener Liner  1  will now be described. 
     When the user wants to put the blade  20  of the knife  2  back into the sheath  1  or to sharpen it, he brings the tip of the knife  2  in front of the diamond-shaped opening, visible in  FIG.  6   , formed by the groove  54  and by the two sharpening elements  60 , and then introduces the blade  20  of the knife  2  into the sheath  1  by a longitudinal movement. During this movement, the back of the blade  20  is centered in the bottom of the V-shaped groove  54  while the cutting part of the blade  20  is centered by the V formed by the two sharpening elements  60 . 
     This double positioning of the cutting part of the blade  20  and the back of the blade  20  makes it possible to obtain a sharpening angle that remains symmetrical and constant throughout the path of the blade  20  in the sheath  1 , without the user having to manually orient the blade  20 . Thus, the symmetry of the sharpening is guaranteed and the sharpening angles are equal on each side of the blade wire, which allows a homogeneous and centered wear of the blade  20 . 
     Moreover, during this introduction or during the extraction of the blade  20  from the sheath  1 , the pivoting movement of the arm  7  allows the sharpening device  6  to follow the profile of the cutting part of the blade  20 , the sharpening device  6  exerting, under the effect of the return spring  8 , a moderate pressure on the cutting part of the blade  20  when the tip of the blade is introduced into the access opening  10  of the sheath  1 , and then an increasing pressure as the height of the blade  20  increases when the knife  2  is introduced into the sheath  1 . The high friction between the cutting portion of the blade  20  and the sharpening elements  60  causes the blade  20  to sharpen. 
     Finally, since the sharpening elements are placed one behind the other, in the direction of insertion of the blade  20 , the possible oscillation of the sharpening device  6  with respect to the second end of the arm  7  allows the sharpening elements  60  to remain in permanent contact with the blade  20  and to remain correctly oriented with respect to the latter, thus optimizing the sharpening of the blade  20 . 
     When the blade  20  of the knife  2  is fully inserted into the sheath  1 , the locking element  55  of the centering ring  50  is inserted into the safety notch  22  on the back of the blade  20  under the effect of the return spring  8 . The knife  2  is then held securely in the sheath  1 . To remove the knife  2  from the sheath  1 , the user must first exert downward pressure on the handle  21  of the knife  2  to pull the locking element  55  out of the safety notch  22 , and then pull the handle  21  of the knife  2  to remove the blade  20 . Such handling avoids any accidental dropping of the knife  2  that might occur, for example, when the sheath  1  is handled for transport. 
     Furthermore, the sheath  1  thus made also has the advantage of allowing easy cleaning of the interior of the sheath  1 . Indeed, the user can easily uncouple the envelope  4  from the base  3  by holding the base  3  with one hand, after having removed the knife  2 , then by exerting a traction on the envelope  4  so that the groove  53  disengages, by elastic deformation of the head  52 , from the locking tab  34  arranged at the top of the grid  31 . The opening  4  can then be slid onto the base  3 , each guide groove  32  of the base  3  having, on the side of the access opening  10 , an open longitudinal end allowing the extraction of the rib  42  of the envelope  4 . After cleaning the inside of the sheath  1 , the envelope  4  can be reassembled on the base  3  by carrying out the operations described above in reverse order. 
     Of course, the invention is in no way limited to the embodiment described and illustrated, since this embodiment was only provided by way of example. Changes can still be made, particularly with regard to the constitution of the various elements or by substituting technical equivalents, without departing from the scope of protection of the invention. 
     Thus, in an alternative embodiment not shown, the casing may not be removable from the base, the base and the sheath casing may for example be made in one piece.