Edger

Details Edger Edger

1999-08-13

2001-09-25

Novosad, Christopher J. (Department: 3671)

Earth working

Lawn edger

Rolling or driven cutter

C172S041000, C172S123000

Reexamination Certificate

active

06293349

ABSTRACT:

TECHNICAL FIELD
This invention relates generally to lawn edgers, and more particularly to an electrically powered lawn edger having a removable wire wheel adapted to cut trenches and to edge along concrete and asphalt surfaces without drawing excessive current from an electric motor of the edger, and also to a system for more positively coupling various edging implements to an output spindle of the electric motor while still permitting such implements to be quickly and easily removed and attached to the spindle.
BACKGROUND OF THE INVENTION
Edgers are used in applications to trim turf growing along a walkway or a driveway where it is desired to produce a clean “edged” appearance to the turf. Such edgers are also often used to cut trenches through turf and into soil to enable cables or wiring to be laid in the soil.
Previously developed edgers, however, have suffered from certain drawbacks when the edger has been used with a wire brush wheel. Wire brush wheels presently available typically include a large number of twisted wire brush segments that are not particularly well suited for use with electrically powered edgers. The large number of wire brush segments are prone to “loading up” with soil and/or turf during use, often temporarily stalling the edger. When this occurs, the edger can also “kick” back toward the user, making use of the edger uncomfortable and tiring.
Such previously developed wire wheels having a large number of wire brush segments also produce a greater current draw on the electric motor of the edger during use than other cutting implements. This can limit the use of many wire wheels to those edgers having motors sufficiently powerful enough to handle the anticipated current draw that will result when using a wire wheel. If the wire wheel becomes momentarily loaded up or stalled during use, the current drawn by the motor will increase significantly and can potentially damage the edger motor.
The problem with excessive current draw with many previously designed wire wheels is further compounded when the edger is used to cut trenches in rocky or stony soil. In these instances, the contact of the wire wheel with stones or rocks increases the risk of loading up or stalling of the motor of the edger, thus increasing the risk of damage to the motor and/or damage to the wire wheel. Stalling can also occur if the wire wheel must cut into hard, compacted soil.
Another disadvantage concerning some previously developed edgers is the somewhat inconvenient process of changing edging implements and/or slippage of the edging implement relative to the spindle of the electric motor driving it. Such edgers often incorporate a number of independent washers and/or threaded nuts for holding the edging implement securely to the motor spindle, which makes changing the edging implement a time consuming and inconvenient process. Often some slippage of the edging implement occurs regardless of how tight the user is able to fasten the edging implement onto the spindle. This slippage can reduce the efficiency of the edger and thus lengthen the time and effort required to complete an edging/trenching task.
In view of the foregoing, it is a principal object of the present invention to provide an edger having a wire wheel which has a reduced number and novel arrangement of wire brush segments which requires less power to be driven by an electric motor than conventional wire wheels used with electric edgers.
It is a further object of the present invention to provide an edger having a wire wheel which is less likely to become momentarily loaded up with soil or turf, or possibly stalled, when digging trenches or edging in hard soil, thereby preventing an unacceptably high current draw by the electric motor of the edger.
It is still another object of the present invention to provide an edger having a wire wheel which may be quickly and easily removed from an output spindle of the electric motor of the edger so that various edging implements such as edging blades and wire wheel brushes can be more quickly and easily attached to the spindle, and where the edging implement is even more securely held to the spindle to prevent undesired slippage of the edging implement relative to the spindle.
SUMMARY OF THE INVENTION
The present invention is directed to a lawn edger having a wire brush wheel and a means for securing the wire wheel, or virtually any other edging implement, quickly and easily to a spindle of an electric motor of the edger in such a manner that slippage of the edging implement relative to the spindle is prevented. The wire wheel of the present invention incorporates a plurality of wire brush segments which are spaced in desired numbers radially about a hub of the wire wheel. In one preferred embodiment, pairs of wire brush segments are positioned closely adjacent one another, with each pair being spaced evenly from its adjacent pair by a predetermined distance. In this manner the overall number of brush segments is reduced while forming “gaps” between each adjacent pair of brush segments. These gaps help to prevent the wire wheel from getting bogged down or stalled when cutting into hard, compacted soil, which could result when using other conventional wire wheels, and thus preventing the edger motor from drawing excessive current.
In the preferred embodiment each twisted wire brush segment comprises a diameter of preferably between about 0.125 inch and 0.5 inch (3.175 mm-12.7 mm). Even more preferably, the diameter of each twisted wire brush segment ranges from about 0.25 inch to 0.375 inch (6.35 mm-9.525 mm). Preferably, the gap between each pair of adjacent wire brush segments is between about 0.5 inch-75 inch (12.7 mm-19.05 mm), and more preferably between about 0.625 inch (15.875 mm), depending on the overall diameter of the wire wheel. These gaps enable dirt and small stones to be readily lifted out by the wire wheel when cutting through hard or highly compacted soil or turf, thus reducing the chance of loading up and stalling of the edger motor.
Each of the wire brush segments are secured to a hub having inner and outer plates and a center plate secured therebetween. The brush segments extend outwardly through openings in the center plate. Preferably, the diameter of each of the inner and outer plates is slightly larger than the diameter of the center plate. Between adjacent pairs of wire brush segments the peripheral edges of the inner and outer plates of the hub are narrowed or “crimped in” slightly toward each other. These narrowed areas help to provide support to the brush segments to maintain the brush segments upright during use of the wire wheel.
In the preferred embodiment, the hub of the wire wheel includes a keyed opening. The spindle of the motor also includes a cross sectional shape which is such that it requires the wire wheel to be placed on the shaft in a particular orientation. A washer having a key shaped boss is also included. The key shaped boss has a shape, when viewed in cross section, which is designed to fit within the keyed opening of the hub such that the washer is not able to rotate independently of the wire wheel when both are placed on the spindle. A threaded fastening member is then used to secure the wire wheel to the motor spindle. In this manner, both the keyed washer and the wire wheel are prevented from rotating independently relative to the output shaft and to each other. This arrangement further enables the wire wheel to be quickly and easily removed and replaced with another edging implement, such as an edging blade, to suit the needs of a specific edging task.
The edger of the present invention thus enables a wire wheel to be used to edge closely adjacent to areas such as concrete, paving stones, asphalt, etc., or to cut trenches in soil without experiencing the loading up or stalling caused by other wire wheels driven by electric edger motors. The wire wheel of the present invention requires less power than traditional wire wheels, thus enabling the wire wheel to be used with edgers having less powerful electric motors. The keyed design

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