Knife Sharpener

Abstract

A knife sharpener has a body with a handle. The body provides a knife blade support surface and an abrasive element support surface set at an included angle that is half a sharpening angle from the support surface. A permanent magnet is used to retain an abrasive element against the support surface of the body. The element may have a thin coating of abrasive material on a ferromagnetic strip having stiffening backing of a plastic. In use, a blade is laid on the support surface and urged away from the handle, while being pulled along the abrasive element. This action grinds into the material of the blade, leaving it with a sharp edge in due course.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a knife sharpener.

2. Background Information

A variety of knife sharpeners are available for manually sharpening knife blades. The majority of these employ a plurality of sharpening elements on one or both sides of the blade being sharpened or at least one element on each side.

At least some of these sharpeners have a tendency to remove metal unevenly from the knife blade being sharpened.

Conventional steels, which are in effect fine round files, remove metal evenly due to their relatively large size, from one side at a time.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a knife sharpener that uses a modern abrasive to sharpen one side of a blade at a time where the sharpening operation results in a blade sharpened with a predetermined sharpening angle.

A preferred embodiment of the invention provides a knife sharpener comprising a combination of a body and an abrasive element. The abrasive element has a pair of parallel faces, one of which is an abrasive face and the other of which is a support face. The body has a handle, a blade support surface, and an abrasive element support surface. The two support surfaces are arranged in a V-shape to define an acute included angle that is half of the sharpening angle provided by the sharpener. In addition, a magnet is used to hold the abrasive element within the sharpener.

Although the invention comprehends devices in which the abrasive element extends to and abuts the blade support surface of the body, such an arrangement can offer a gap between the abrasive element and the body in which the blade can jam. Hence, in a particular preferred embodiment, the blade support surface has a recess into which the abrasive element extends, thereby avoiding such a gap.

In a preferred embodiment the abrasive element has a ferromagnetic plate so that it can be held against the abrasive element support surface by a permanent magnet that may be inserted into a hole in the body of the sharpener.

In preferred embodiments shown in the drawing, the handle of the sharpener extends generally along the blade support surface away from the abrasive element. In this configuration pushing the blade towards the abrasive element while drawing the blade along it can be reacted by pulling on the handle in the direction of its extension from the blade support surface. The skilled reader will recognize that other configurations, such as having a handle extending perpendicular to the blade support surface, are possible but do not offer the ease of use of the preferred embodiment.

Although it is believed that the foregoing rather broad summary description may be of use to one who is skilled in the art and who wishes to learn how to practice the invention, it will be recognized that the foregoing recital is not intended to list all of the features and advantages. Those skilled in the art will appreciate that they may readily use both the underlying ideas and the specific embodiments disclosed in the following Detailed Description as a basis for designing other arrangements for carrying out the same purposes of the present invention and that such equivalent constructions are within the spirit and scope of the invention in its broadest form. Moreover, it may be noted that different embodiments of the invention may provide various combinations of the recited features and advantages of the invention, and that less than all of the recited features and advantages may be provided by some embodiments.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a knife sharpener in accordance with the invention;

FIG. 2 s a plan view of the sharpener of FIG. 1 and

FIG. 3 is a side view of the sharpener, with a knife being sharpened shown in section.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings, the knife sharpener has a body 1 with a handle 2. At the end of the handle that is proximal the abrasive element 6, the body spreads out to provide a knife blade support surface 3. From the edge of the blade support surface that is remote from the handle, an abrasive element support surface 4 extends at an acute angle back towards the handle and away from the blade support surface in a V shape. A permanent magnet 5 inserted into the sharpener body near the center of the support surface 4 coacts with a ferromagnetic portion of the abrasive element 6 to pull it against the surface 4. In one embodiment the abrasive element 6 has a thin coating of abrasive material 7 on a ferromagnetic strip 8 and a stiffening backing 9 of a polymeric material. The preferred blade support surface has a recess 10 into which an edge 11 of the abrasive element extends.

In use, a blade B is laid on the support surface 3 and urged away from the handle while being pulled along the abrasive element 6. This action grinds the material of the blade, leaving it with a sharp edge 12 in due course.

The abrasive element is held at a predetermined acute angle α, typically 20°, with respect to the blade support surface. Thus, one ground face of the blade 13 is at 20° to its opposite blade face 14. After sharpening one side, the knife sharpener is then turned over and the other face 15 of the blade is ground at 20° to its opposite blade face 16. The result is that the blade is sharpened with a sharpening angle β of 40°.

Accurate, repeatable sharpening is possible. The preferred abrasive element is diamond impregnated. To change the element—for instance between coarser and finer grits,—the user first removes the permanent magnetic retaining plug and then slides the element out along the support surface. In the embodiment depicted in FIG. 3 two scallops 17 are provided for access to the support surface of the element.

Although the present invention has been described with respect to several preferred embodiments, many modifications and alterations can be made without departing from the invention. Accordingly, it is intended that all such modifications and alterations be considered as within the spirit and scope of the invention as defined in the attached claims.

Claims

1) A knife sharpener comprising:

an abrasive element having a pair of parallel face, one of the faces being an abrasive face and the other being a support face, the abrasive element comprising a ferromagnetic portion;

a body comprising a handle, a blade support surface extending from the handle, and an abrasive element support surface, wherein the blade support surface and the abrasive element support surface are arranged in a V shape to define an acute included angle that is half a sharpening angle of a blade sharpened on both sides by the sharpener; and

a permanent magnet detachably insertable into a portion of the body adjacent the support surface for holding the support face of the abrasive element against the support surface.

2) The knife sharpener of claim 1, wherein the abrasive element extends to and abuts with the blade support surface.

3) The knife sharpener of claim 1, wherein the blade support surface comprises a recess into which the abrasive element extends, thereby avoiding a gap between the abrasive element and the support face in which a blade being sharpened could jam.

4) The knife sharpener of claim 1, wherein the blade support surface extends transversely of the handle.

5) The knife sharpener of claim 1, wherein the body further comprises two scallop cuts in the abrasive element support surface for access to the support face of the abrasive element.