Abstract:
A blade sharpening apparatus having a hollow housing with an internal drive motor for inducing back and forth movement on a pair of aligned elongated abrasive stones. The abrasive stones are retained by a stone holder and possess a cross section in the form of a equilateral triangle. A slidable guide is slidably mounted on the housing above the pair of abrasive stones. The abrasive stones have a portion of two faces extend through the slidable guide. The slidable guide includes a pair of flat guide surfaces for supporting a blade to be sharpened.

Description:
This application claims benefit of provisional application 60,097,057 filed Mar. 23, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to knife sharpeners and more specifically, to a blade sharpening apparatus capable of sharpening knives having serrations or having flat edges. 
     2. Description of the Prior Art 
     Typically, knives for many uses are constructed with a blade having either a serrated cutting edge or a flat edge. A serrated edge is particularly difficult to sharpen. Because of the nature of a serrated edge of a blade and its possible range of dimensions, known sharpener devices have not been able to satisfactorily sharpen both a serrated edge of a wide range of sizes and a straight edge in an effective manner. Prior sharpener designs have required that the sharpening stone be replaced by other stones in order to sharpen either a serrated edge, accommodate all sizes of serrations, and also sharpen flat edges. Known sharpeners also have a tendency to operate at high speeds that can cause heat build up and remove the temper of the knife blade. Past known devices are further deficient in providing a guide that permits sharpening to occur at optimum angles. Accordingly, there is a need in the prior art to provide an improved knife sharpener capable of sharpening knives having serrated edges of all sizes and flat edges as well in an efficient and effective manner. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an objective of this invention to provide an improved blade sharpening apparatus capable of sharpening knives and the like having serrated edges of all sizes and flat blades. The invention of the application includes sharpening stones having an unique triangular configuration of equal sized faces that allow for superior sharpening of serrations and that allow the stones to be rotated to extend wear. The stones are moved in a back and forth stroke by an improved drive mechanism to assure superior sharpening. A slidable blade guide allows the user to select a coarse stone for initial edge sharpening or to repair damaged edges or alternatively, a fine stone to grind a final finished edge on the knife or to sharpen already sharp knives. The slidable guide also acts to provide a guide surface to sharpen a blade at an optimum angle. The knife sharpener of the invention is portable in nature and can be powered by batteries or other sources of electrical potential. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a partial side elevational view of the blade sharpener apparatus of the invention and showing one-half of the interior of the housing; 
     FIG. 1 a  is a side elevational view, with parts removed, of the exterior of the housing of FIG. 1; 
     FIG. 1 b  is an end elevational view,,with parts in section, taken along lines  1   b — 1   b  of FIG. 1 a ; 
     FIG. 2 is a partial side elevational view, with parts removed, of the other half of the blade sharpener apparatus of the invention, showing the drive mechanism and other half of the housing; 
     FIG. 3 is a partial end elevational view, with parts in sections, taken along lines  3 — 3  of FIG. 2; 
     FIG. 4 is a top plan view of the blade angle guide of the blade sharpening apparatus of FIG. 1; 
     FIG. 5 is a side elevational view of the blade angle guide of FIG. 4; 
     FIG. 6 is an end elevational view of the angle guide of FIG. 4; 
     FIG. 7 is a top plan view of the stone holder of the blade sharpener apparatus of FIG. 1; 
     FIG. 8 is an end elevational view of the stone holder of FIG. 7; 
     FIG. 9 is a bottom plan view of the stone holder of FIG. 7; 
     FIG. 10 is a front elevational view of the stone holder of FIG. 7; 
     FIG. 11 is a top plan view of the stone holder rack of FIG. 11; 
     FIG. 12 is a front elevational view of the stone holder rack of FIG. 11; 
     FIG. 13 is an end elevational view of the stone holder rack of FIG. 11; 
     FIG. 14 is a bottom plan view of the blade angle guide of FIG. 4; and 
     FIG. 15 is a side elevational view taken along lines  15 — 15  of FIG.  14 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1,  1   a,    1   b,    2  and  3 , there is illustrated the improved blade sharpening apparatus of the invention, generally designated by reference numeral  2 . In FIG. 1, a first half portion  4   a  of housing  4  of the blade sharpening apparatus  2  is shown. The half portion  4   a  substantially conforms to the configuration of the other half portion  4   b  of the housing  4  which is illustrated in FIG.  2 . The two housing portions  4   a,    4   b  to form housing  4  are retained together by suitable mechanical fasteners and retention elements (not shown). Referring to FIGS. 1,  1   a  and  2 , the two portions  4   a  and  4   b  of the housing  4  include handle openings  8   a  and  8   b  formed on an enlarged end  6  of housing by which the blade sharpening apparatus  2  can be manipulated by a user. Housing  4  including portions  4   a  and  4   b  may be formed from a suitably durable plastic material. 
     The blade sharpening apparatus  2  is powered by a conventional electric motor  10  capable of rotating a pinion gear  12  rotatably attached to the output shaft of the motor  10 . The motor  10  can be any type of electric motor that can be powered by electrical batteries (not shown) or an external electrical power source. The electrical batteries are arranged to be mounted in a suitable manner (not shown) within housing  4 . In one form of the invention, the motor is driven by four “C” cell batteries, but other batteries may be used dependent on motor requirements. The batteries are electrically connected to leads  10   a  and  10   b  by a conventional electrical circuit by which an external on/off switch (not shown) is used to actuate the electric motor  10  as needed. As seen in FIG. 3, the motor is mounted on two pairs of rigid rods  10 ′ (two of which are shown in FIG. 3) at both ends of motor  10  in a manner to secure the motor in position as shown within housing  4 . A pinion gear  12  engages a crown gear  14  that is secured to a shaft  18  and extends transverse to the axis of rotation of the pinion gear  12 . The end  18   a  of shaft  18  engages the U-shaped slot  20   a  of the actuator lever  20  as seen in FIG.  3  and FIG.  10 . The shaft  18  is mounted on off-center axis with respect to the center of the crown gear  14  to drive the actuator lever  20  and produce a back and forth motion on the actuator lever  20 . As seen in FIG. 3, the actuator lever  20  extends up through a opening  22  provided in an intermediate upper wall  24  of housing  4 . 
     The top end of actuator lever  20  is secured to a grinding stone holder  30  as seen in FIGS. 2,  3  and  10 . The stone holder  30  includes a pair of pockets  32  for respectively receiving a pair of grinding stones  34  and  36  as shown in FIG.  1 . The stones  34  and  36  respectively comprise a fine stone and a coarse stone for various sharpening operations. For example, the coarse stone  36  may be used to sharpen the serrated edge or flat edge of a damaged blade or can be used in an initial sharpening operation. The fine stone  34  can be used to finish a sharpening operation or to sharpen up relatively sharp edges. As will be discussed later, the stones  34  and  36  can be alternately exposed for sharpening by sliding the angle guide  38  that is disposed above the stones. The angle guide  38  is slidable in either direction to expose one of the stones  34 ,  36  and cover the other stone as will be described later. As seen in FIGS. 1 and 2, the stones  34  and  36  are mounted above housing top  24  in a depressed area which is disposed intermediate of the length of the housing  4 . The actuator lever  20  moves the stone holder  30  and the stones  34 ,  36  in a limited back and forth stroke along the longitudinal axis of the housing  4  for an extent, for example, of {fraction (1/16)}″ or other suitable distance. 
     In FIGS. 7,  8  and  9 , it is shown that the two pockets  32  of stone holder  30  are closed at one end by triangular shaped projections  40 . The stones  34  and  36  each have a triangular cross section of a configuration having equal sides by which a lower flat side rests respectively in pockets  32  of the stone holder  30 . The stone holder  30  includes a pair of holes  42  by which a screw or other threaded member may engage the stones  34  and  36  to retain them in position on stone holder  30  and allow that the stones to be removed. Because of the triangular shape of the stones  34  and  36 , they are capable of being rotated to extend the useful lifetime service of sharpening. The unique shape of the triangular stones further effectively sharpens serrated blade edges of any size and can also be used to sharpen flat blades with effectiveness without changing the stone. The lower body  44  of the stone holder  30  is mounted on a stone holder rack  50  as best seen in FIGS. 11,  12  and  13 . The area of the cross-section of stones  34  and  36  is larger than the area of triangular shaped projections  40 , such that the upper surfaces  34   a,    36   a  extend beyond projections  40  as shown in phantom in FIG.  3 . The stone holder  30  is further provided with a pair of open ended slots  46  at each end. Both the stone holder  30  and the stone holder rack  50  may be fabricated from a plastic or other durable material. 
     Referring now to FIGS. 1,  2 ,  3  and  11  to  13 , there is illustrated the stone holder rack  50  upon which is the stone holder  30  is mounted. The stone holder rack  50  is suitably retained on housing  4  and permits the back and forth motion of the stone holder rack  50 . The stone holder rack  50  includes a flat bottom member  52  having an opening  54  through which actuator lever  20  extends. A pair of the flat projections  56  project upward at a position inward from the opposite edges of flat bottom member  52 . Two pairs of aligned holes  58  are provided in upward projections  56 . The holes  58  receive pins  60  as best seen in FIG. 1 with said pins  60  being positioned in end slots  46  of stone holder  30 . The pins  60  retain the stone holder  30  and stones  34 ,  36  from raising up when pressure is being applied by a blade to a stone during sharpening. 
     Referring to FIGS. 1,  4 ,  5 ,  6 ,  14  and  15  details of the blade angle guide  38  are shown. Although not so limited, the blade angle guide  38  can be fabricated from a suitable metal and the like. The blade angle guide  38  is formed as a one-piece body  70  having an intermediate upper blade sharpening section  72 . The sharpening section  72  includes a pair of lower ledges  74  intersecting a pair of sloped side surfaces  76 . The side surfaces  76  terminate with a pair of flat blade angle surfaces  80  and  82  which angle downward toward the center of blade sharpening section  72 . The angles of incline of surfaces  80 ,  82  are selected to act as a base surface and guide for a blade (not shown) being sharpening for engaging a selected stone  34  and  36  at an optimum angle. An opening  84  is provided in surfaces  80  and  82  to allow the upper edge portion (FIG. 1) of either triangular stone  34  or  36  to project upward through opening  84  for sharpening. The sharpening section  72  is integral with two end portions  86  and  88  by two pairs of transverse sections  90 ,  92  disposed above ledges  74  and adjacent sloped surface  76 . The end portion  86  is formed by an upper surface  96  and a pair of side sections  98  forming an open bottom in a modified inverted U-shape. The end portion  88  similarly includes an upper surface  100  and a pair of side sections  102  also having a modified inverted U-shape. The outer surface of at least end portion  88  has a gripping surface, such as ribs  88   a  as shown in FIG. 4,  5 ,  6 ,  14  and  15 . 
     As seen in FIGS. 1,  1   a  and  1   b  the blade guide is moveable between a wall  104  correspondingly formed on housing portions  4   a,    4   b  to stop surface  106  adjacent one end of housing  4 . The housing  4  forms an open blade guide compartment  108  for the receiving end portion  86  of blade guide  38  in the position shown in FIG.  1 . As seen in FIG. 1, the compartment  108  is formed by back wall  104 , upper and lower walls  110   a,    110   b  and side wall  112  (one of which is shown) which have a configuration to receive end section  86  through opening  113  with end  86   a  of end portion  86  is in contact or near contact with a back wall  104 . In the position of blade angle guide  38  shown in FIG. 1, stone  36  is exposed for sharpening, while stone  34  is covered. 
     The blade guide  38  is further moveable to a second position exposing stone  34  and covering stone  36  by which the end  88 ′ of portion  88  contacts or is in near contact with stop  106 . The end portion  88  moves into surrounding exterior relation to upper reduced section  114  of the housing  4  having a correspondingly similar but smaller configuration than the cross sectional shape of end portion  88  as seen in FIGS. 1 a  and  1   b.  The blade guide  38  moves on its lower edge along the housing  4  on lower wall l 110   b,  wall  24  and a ledge  116 . The ledge  116  is outwardly disposed below upper reduced section  114  under which a slot  118  is formed. As seen in FIGS. 6 and 14, a pin  120  is attached to the lower edges of end portion  88  of blade guide  38  to engage the slot  118  for movement and securement. A portion of the end portion  86  of blade guide  38  is captured in compartment  108  when end  88 ′ contacts stop  106  to aid in securement.