Patent Application
20060207235
This Application claims the benefit of the U.S. Provisional Application Ser. No. 60/662,422 filed Mar. 16, 2005 (hereinafter “the Provisional Application”) which is hereby incorporated by reference in its entirety.
A conventional homeowner lawn maintenance solution includes a push or walk-behind mower and a full-size string trimmer. The homeowner mows the accessible areas of the grass with the mower, however there are some areas the mower cannot reach, which are typically alongside fences and objects surrounded by grass. Following mowing, a typical homeowner stows the mower and takes up a string trimmer to tidy these inaccessible areas.
An ordinary, full-size string trimmer is designed to trim large areas of grass. For example, a homeowner having grass planted abutting a fence may trim the grass at the fence by sweeping the full-size trimmer generally along the length of the fence. While the homeowner has the trimmer out, he will trim central areas around trees, poles, flowerbeds and the like. Commonly, a string trimmer will be designed and marketed to trim not only small patches of relatively short grass, but also to clear weeds and tall grass. For this, a typical full-size string trimmer includes a relatively large power plant to drive its string through thick stems, leaves and cut debris while continuing to rotate its head at an acceptable speed. These power plants are conventionally either two-cycle combustion engines or electric motors.
A number of years ago string trimmers were commonly electric, connectible to ordinary AC power through an extension cord. The homeowner dragged the cord with him as he went, but that was preferable to trimming the grass by hand. This burden was relieved somewhat by the availability of portable gas-powered string trimmers, but due mainly to the size and weight of the engine required these are not comfortably used or carried in tandem with other yard-care equipment. Gas-powered trimmers also require some maintenance, mainly in relation to fuel replenishment and engine care.
One additional homeowner burden introduced by conventional string trimmers is that of making two passes across the yard: one to mow and one to trim. Some attempts have been made to combine a mowing operation with a trimming operation, generally by incorporating a string trimmer into a lawn mower powered thereby. Of these, many incorporate a trimmer head fixed to a mower deck, such as that described in U.S. Pat. No. 4,170,099 to Owens. Mowers of that type might be conveniently used near fences, as the operator would likely pass alongside a fence anyway. However, for trimming around small objects such a mower would need to be moved from side to side, which would require maneuvers against the generally forward mower motion for which it is principally designed. Solutions of this kind also introduce new moving parts and maintenance issues, and although several examples of solutions of this type have appeared in issued patents, mowers that incorporate a string trimmer have not attained popularity perhaps for these reasons.
Other designs have incorporated a string trimmer to a lawn mower, not fixably mounted. For example, U.S. Pat. No. 4,242,855 to Beaver describes a string trimmer powered through a flexible shaft coupled to the mower engine's crankshaft. Apparently, there are few solutions to providing driving power to a portable string trimmer head from a mower engine, and thus these designs appear infrequently. Furthermore, it seems likely that maintenance issues would outweigh the advantages; a flexible shaft would rotate at a fairly high rate and could suffer from cable breaks due to kinking or loss of lubricant over seasonal use.
Other aspects of combining a lawn-mower with a string trimmer have challenged prior designers. Most, if not all, of the prior designs incorporate essentially a full-sized trimmer or trimmer head as described above. Thus one might categorize the prior designs as either a string-trimmer head mounted to a mower deck, or a full-sized trimmer mounted to a riding mower/tractor such as that described by Aldrich in U.S. Pat. No. 5,802,824. Although many of the riding mower designs incorporate a fixed trimmer on a mower base, Aldrich cleverly adds removability of his trimmer for use apart from the riding mower. Aldrich's solution, however, is not suitable for the majority of homeowners who occupy a lot size of well less than one-half acre and do not have a substantial outbuilding large enough to store a riding mower. Thus in order to serve the majority of homeowners, a trimming product must be combinable with a walk-behind self-propelled or push mower.
For a homeowner with large areas of fence line to trim, use of a full-sized string trimmer may be acceptable. For him, the inconveniences of equipment care and the additional time to stow his mower and retrieve a string trimmer may be compensated with the efficiency with which his full-sized trimmer trims his many areas not reachable by his mower. However, there are some homeowners who have little trimming to do. Lawn areas abutting a sidewalk, driveway or other flat surface level with the lawn can be entirely cut by passing the mower over the lawn interface, although some seasonal edging may be required. Some homeowners deliberately place such mow-strips under fences to permit the mower to ride on the strip on one side, while preventing grass from growing directly under a fence. Traditionally, homeowners have also edged their grass with objects buried partially in the ground, providing a barrier to the expansion of grass. These objects have often had a substantial vertical profile, preventing a lawn mower to pass over these edges without substantial damage. Recently a product has become available that provides both an edging and a mow strip in the same block, and can be used to surround flowerbeds, trees or placed alongside fences to provide a mow strip and reduce or eliminate the need to trim grass.
A homeowner utilizing mow-strips, blocks and other products may have very few areas to trim, which might be reduced to the area around a few trees, or the legs on a child's swing set. For such a homeowner prior grass trimmers become cumbersome.
The inventions relate generally to devices for trimming grass, such as string trimmers, that are attachable to a lawn mower and usable while mowing a lawn. More particularly, the inventions relate to a light-duty string trimmer wand attachable to a walk-behind lawn mower and independently operable to trim small areas of grass. Detailed information on various example embodiments of the inventions are provided in the Detailed Description below, and the inventions are defined by the appended claims.
Reference will now be made in detail to some embodiments of the inventions, examples of which are illustrated in the accompanying drawings.
Disclosed herein are trimmer products attachable to a push mower, the first example of which is shown in
The exemplary trimmer wand 10 is designed to be attached to the tubular portion of a walk-behind mower handle, and wand 10 can be coupled to a mount securable to a tubular handle, which in this example is by a clamping interlock 20. Best viewed in
Use of the trimmer wand 10 and interlock 20 is depicted generally in
As the operator 32 mows his lawn he may encounter an obstruction 33, which might in this drawing be a post, which prevents the mower 30 from cutting the grass nearby the obstruction. Momentarily, the operator stops the motion of mower 30, which may or may not involve stopping its engine. Operator 32 then withdraws wand 10 from interlock 20 by lifting it generally in the direction marked 34, or by pulling generally toward the operator standing behind mower handle 31. Operator 32 grasps the wand 10 and depresses switch 16 activating rotation of head 16 and thereby trimming around post 33. Note that because wand 10 is powered internally, it operates independently of mower 30 without any connection to the mower required. The length of wand 10 may be made to be approximately 30 to 38 inches, placing head 12 at a comfortable level with respect to the ground when held out at an angle and away from the operator's body. When finished, operator 32 replaces wand 10 back into interlock 20, in this configuration also by a sliding motion, and continues to mow as before. Note that because wand 10 is available to the operator 32 when an obstacle 33 is encountered, he need not move from the immediate vicinity of lawn mower 30 to trim the grass around the obstacle.
Now the use of the exemplary wand 10, or others disclosed herein, provides several benefits. First, as most walk-behind mowers incorporate a tubular handle, a wand can be added as an attachment to virtually all walk-behind mowers. Because the wand is relatively small, it may be stored beneath a typical walk-behind lawn mower handle, and no additional storage space in a garage or shed is needed. Additionally, the weight of the wand can be reduced to the point that the wand can be controlled with one hand. If a homeowner can operate a trimming wand with one hand, he can keep a safety control lever depressed with the other and potentially avoid restarting his lawn mower while trimming. A typical walk-behind lawn mower weighs about 70 to 100 lbs., and a wand weighing about 5 lbs. or less is comparatively light and is not likely to be an encumbrance to a lawn mower operator. With careful choice of a motor, batteries and other components, a wand might be constructed weighing about two to three lbs or even less.
The components of the wand contributing the most to the weight are the batteries and motor, as the housing and other components can be made from plastics or other light-weight materials. The housing of a wand can also be constructed with thinner walls, due to its lighter-duty requirements. In one implementation, a wand is constructed having about a 2 cm diameter with walls about 2 mm in thickness, permitting AA size batteries to be housed therein.
A wand may utilize a DC motor having a sufficient torque and rotational speed for the desired use. One implementation utilizes an HC783LG or similar motor available from Johnson Electric of Tai Po, Hong Kong (www.johnsonelectric.com), having a speed of about 14,000 to 16,000 RPM at a current of about 1.8A at 12 V and no load. Alternatively, a Stinger motor manufactured by Traxxas of Plano, Tex. (www.traxxas.com), requiring 1.2 A at 12 V and rotating at 17,500 RPM may also be used. A motor in the Havoc line from Team Orion of Yorba Linda, Calif. (www.teamorion.com) is also a suitable choice. A rotational speed of about 10,000 to 20,000 RPM may provide good performance: a high RPM or high power motor may provide improved trimming efficiency although depleting batteries more quickly. Should a high-current motor be chosen, it may be necessary to provide venting in the housing near the motor. Generally, motors manufactured for remote-controlled cars or boats are suitable due to their high power and/or speed and light weight, which may be under 2 lbs. If desired, a motor may be placed toward the handle portion through the use of a straight or geared shaft coupled to the motor, which may improve the balance of a wand by moving the center of gravity toward the handle. Also, a wand housing might be made to fit motor magnets, armatures, contacts and other parts, taking the place of an independent motor housing and potentially reducing weight and/or cost.
As suggested above, dry cell batteries are an acceptable choice for some applications. For the 12V Johnson motor above, it may be useful to use 8 or 9 C or D cells providing up to several hours of use per charge. In such a configuration, it may be expected that a set of batteries might last sufficiently long for some users to make battery replacement a start-of-the-season maintenance activity. AA cells might also be acceptable if a lower-current motor is used. Other battery configurations may be used consistent with the desired portability and use of the trimmer product. With the use of C size batteries and a motor as suggested above, a wand could weigh as little as five or six lbs and not encumber an operator's control of a lawn mower to which it may be attached. With AA size batteries, a further weight reduction could be made at the expense of available current for the motor and battery life.
The shape of a trimmer wand may be almost infinitely varied. In the example shown in
A handle or gripping portion of a wand may have incorporated therein texturing, finger recesses, serrations or other shaped features to improve control or comfort. A handle may also include additions, such as a surrounding rubber or foam grip.
The interlock shown in
Now turning to
Conventional string trimmer heads utilize a string spool and a mechanism to release additional string as it wears under use. Although such techniques may be employed with a trimmer wand, it may be desired to use a non-spooling trimmer head as depicted in
A trimmer wand as disclosed herein may also include a guard, for example the one depicted in
A guard may also be retractable or fixed. Shown in
While the present systems, products and methods have been described and illustrated in conjunction with a number of specific configurations, those skilled in the art will appreciate that variations and modifications may be made without departing from the principles herein illustrated, described, and claimed. The present invention, as defined by the appended claims, may be embodied in other specific forms without departing from its spirit or essential characteristics. The configurations described herein are to be considered in all respects as only illustrative, and not restrictive. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
| Number | Date | Country | |
|---|---|---|---|
| 60662422 | Mar 2005 | US |
