SELF-CLEANING GEAR ASSEMBLY FOR PENCIL SHARPENERS

Abstract

A gear assembly that includes a cutting gear having an outer edge and an inner edge, wherein a plurality of gear teeth is formed on the outer edge thereof; and an internal gear having an outer edge and an inner edge. The internal gear further includes a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear; a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

Description

BACKGROUND OF THE INVENTION

The described invention relates in general to sharpening devices and the like, and more specifically to a pencil sharpener that includes a self-cleaning mechanism for automatically removing debris from the gear set that forms a portion of the cutting mechanism of the pencil sharpener.

This invention relates to the fixed internal gear that drives the helical cutter in manual and electric pencil sharpeners by way of the cutter gear, which is attached to one end of the cutter. Because this gear set is most conveniently located adjacent to the pencil cutting area and in the same compartment with the pencil shavings receptacle, it is exposed to wood shavings and ground pencil core debris (“foreign material”). When this debris enters the gear set, it is often pressed into the troughs of the internal gear. If allowed to accumulate, this material can begin to physically obstruct the cutter gear teeth entering into the internal gear teeth, eventually jamming the gear set and preventing further sharpening.

Conventional techniques for addressing this problem include covering the internal gear or adding additional clearance to the gear set. Covers, typically attached to the rotating carrier, are designed to prevent pencil shavings from entering the gear set. These covers are somewhat effective, but it is difficult to completely seal the gear set without increasing the cost or complicating the assembly. Additional clearance has been added to the gears by increasing backlash or reducing (since one of the gears is an internal gear) the center-to-center distance, but this too is only marginally effective. Thus, there is an ongoing need for pencil sharpener that includes a self-cleaning mechanism for automatically removing foreign material from the gears involved in sharpening.

SUMMARY OF THE INVENTION

The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope.

In accordance with one aspect of the present invention, a pencil sharpener is provided. This pencil sharpener includes rotating cutter carrier, wherein the cutter carrier is adapted to receive a pencil for sharpening; a helical cutter mounted on the rotating cutter carrier; and a gear assembly adapted to cooperate with the helical cutter, wherein the gear assembly further includes: cutting gear having an outer edge and an inner edge, wherein a plurality of gear teeth is formed on the outer edge thereof; and an internal gear having an outer edge and an inner edge. The internal gear further includes a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear; a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

In accordance with another aspect of the present invention, a gear assembly is provided. This gear assembly includes a cutting gear having an outer edge and an inner edge, wherein a plurality of gear teeth is formed on the outer edge thereof; and an internal gear having an outer edge and an inner edge. The internal gear further includes a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear; a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

In yet another aspect of this invention, an internal gear for use in a sharpening device is provided. This internal gear includes a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear; a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein:

FIG. 1 is a perspective view of a pencil sharpener in accordance with an exemplary embodiment of the present invention;

FIG. 2 is a first front perspective view of a gear assembly in accordance with an exemplary embodiment of the present invention;

FIG. 3 is a detail of the front perspective view of FIG. 2;

FIG. 4 is a second front perspective view of a gear assembly in accordance with an exemplary embodiment of the present invention;

FIG. 5 is a cross-sectional detail of the gear assembly FIG. 4;

FIG. 6 is a third perspective view of a gear assembly in accordance with an exemplary embodiment of the present invention;

FIG. 7 is a side view of the gear assembly of FIG. 6;

FIG. 8 is a front view of an internal gear in accordance with an alternate embodiment of the present invention, wherein the shape of the grooves broaden after passing through the internal gear tooth profile; and

FIG. 9 is a perspective view of the internal gear of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention are now described with reference to the Figures. Although the following detailed description contains many specifics for purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

With reference generally to the Figures, the present invention provides a self-cleaning or self-clearing gear assembly that reduces jamming and excessive wear of the cutter gear and internal gear system used in pencil sharpeners and the like due to the accumulation of foreign material such as pencil shavings and core material generated during use of the sharpener. Even when such accumulation doesn't completely jam the gear set, the presence of foreign matter in the gear teeth can cause accelerated wear on the internal gear teeth (which are typically polymeric/plastic for cost reasons, but may also be metal) by abrasion and induced interference.

FIG. 1 provides a perspective view of an electric pencil sharpener in accordance with an exemplary embodiment of the present invention, wherein the covers and/or enclosure has been removed to show the placement and location of internal components. This pencil sharpener includes a substantially horizontal bottom section which supports a receptacle for collecting shavings, and a substantially vertical internal frame and support upon which and to which various other system components are mounted or attached. This pencil sharpener includes a motor and a sharpening assembly that further includes a pencil receiving portion (i.e., rotating cutter carrier) having an opening formed therein, a helical cutter, and a gear assembly. The gear assembly includes cutter gear that is driven by the motor and a fixed internal gear that may be molded into the internal support or that may be a separate component. As shown in FIGS. 1-9, a rectangular groove or channel is formed at the root or bottommost portion of the trough between each of the gear teeth on the fixed internal gear. The embodiments depicted in the Figures include 25 of these grooves, although the total number of grooves may differ in alternate embodiments, When the cutter gear engages the internal gear, the action and motion of the cutter gear causes any foreign material (e.g., wood or paper shavings from a pencil or crayon) that may accumulate between the teeth of the internal gear during sharpening to be discharged or cleared from the internal gear by way of the grooves.

As shown in FIG. 5, the discharge grooves or channels may be angled at about 45° (or at another suitable angle) from the longitudinal axis of the internal gear for discharging debris in a forward direction and into the shavings receptacle. In other embodiments, the grooves are not significantly angled. In still other embodiments, the grooves or channels pass completely though the internal gear and debris is discharged in a rearward direction and/or in a forward direction. In the embodiment shown in FIGS. 8-9, the grooves on the internal gear broaden after passing through the gear teeth so that once shavings pass through the neck of the gear profile (i.e., troughs), they are more freely discharged into the shavings receptacle. These grooves or channels are intended for inclusion on the internal gear and some embodiments on the mating cutter drive gear of pencil sharpeners. In some embodiments, the internal gear is a molded plastic component that cooperates with other molded internal components and in other embodiments, the internal gear is a separate part die-cast from zinc or other metal(s). Generally, debris accumulation does not affect the cutter gear as much as the internal gear because its higher rotational velocity tends to throw of foreign material or debris; however, there may be a benefit for use with sticky colored pencil core materials that can cling to the cutter gear. This design may also be suitable for other applications, especially in the proximity of cutting operations, where scraps of foreign material may be present.

With the present invention, it is also desirable for both the internal and cutter gear teeth to be open on both sides (i.e., no internal comers at the troughs of the gears). Internal comers are sometimes caused by flanges added to the cutter side of the cutter gear, and on the internal gear by molding teeth into an existing structural component of the sharpener to just beyond the gear design width. Additionally, this improvement is envisioned in conjunction with a bevel gear design (see FIG. 5) for the fixed internal and cutter gears. Traditionally, these gears were spur gears and the angular misalignment was neglected for the individual gear design. Only the center distance, tip radius of the cutter gear teeth, and the internal gear inside diameter were modified to provide additional clearance to eliminate the interference due to the angular misalignment.

Some embodiments of this invention include a “wiper” in the form of a finger, arm, bar, extension, or similar structure extending from the rotating cutter carrier that helps to clear shavings that begin to align and protrude from the grooves as the shavings are being ejected.

While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.

Claims

1. A pencil sharpener, comprising; (a) rotating cutter carrier, wherein the cutter carrier s adapted o receive pencil for sharpening;(b) a helical cutter mounted on the rotating cutter carrier; and(c) a gear assembly adapted to cooperate with the helical cutter. wherein the gear assembly further includes: (i) cutting gear having an outer edge and an inner edge, wherein a plurality of gear teeth is formed on the outer edge thereof; and(ii) an internal gear having an outer edge and an edge, wherein the internal gear further includes: a) a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear;b) a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; andc) a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

2. The gear assembly of claim 1, wherein the internal gear is a molded plastic component.

3. The gear assembly of claim 1, wherein the internal gear is die-east metal component.

4. The gear assembly of claim 1, wherein the debris discharge channels are angled at about 45° from the longitudinal axis of the internal gear for discharging debris in a forward direction.

5. The gear assembly of claim 1, wherein the debris discharge channels pass completely through the material of the internal gear.

6. The gear assembly of claim I, wherein the width of each debris discharge channel increases as the debris discharge channel extends toward the outer edge of the internal gear.

7. A gear assembly for use in a sharpening device, comprising: (a) a cutting gear having an outer edge and an inner edge, wherein a plurality of gear teeth is formed on the outer edge thereof; and(b) an internal gear having an outer edge and an inner edge, wherein the internal gear further includes: (i) a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear;(ii) a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and(iii) a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

8. The gear assembly of claim 7, wherein the sharpening device is a pencil sharpener.

9. The gear assembly of claim 7, wherein the internal gear is a molded plastic component.

10. The gear assembly of claim 7, wherein the internal gear is die-cast metal component.

11. The gear assembly of claim 7, wherein the debris discharge channels are angled at about 45° from the longitudinal axis of the internal gear for discharging debris in a forward direction.

12. The gear assembly of claim 7, wherein the debris discharge channels pass completely through the material of the internal gear.

13. The gear assembly of claim 7, wherein the width of each debris discharge channel increases as the debris discharge channel extends toward the outer edge of the internal gear.

14. An internal gear for use in a sharpening device, wherein the internal gear has an outer edge and an inner edge and further comprises: (i) a plurality of gear teeth formed on the inner edge thereof, wherein the gear teeth formed on the inner edge of the internal gear are adapted to engage the gear teeth formed on the outer edge of the cutting gear;(ii) a plurality of troughs, wherein each trough in the plurality of troughs is formed between two of the gear teeth formed on the inner edge of the internal gear; and(iii) a plurality of debris discharge channels, wherein each debris discharge channel is formed at the bottommost portion of each trough and extends away from the trough toward the outer edge of the internal gear.

15. The gear assembly of claim 14, wherein the sharpening device is a pencil sharpener.

16. The gear assembly of claim 14, wherein the internal gear is a molded plastic component.

17. The gear assembly of claim 14, wherein the internal gear is diecast metal component.

18. The gear assembly of claim 14, wherein the debris discharge channels are angled at about 45° from the longitudinal axis of the internal gear for discharging debris in a forward direction.

19. The gear assembly of claim 14, wherein the debris discharge channels pass completely through the material of the internal gear.

20. The gear assembly of claim 14, wherein the width of each debris discharge channel increases as the debris discharge channel extends toward the outer edge of the internal gear.