GB2348101A

GB2348101A - Balanced portable grass trimmer

Info

Publication number: GB2348101A
Application number: GB0004441A
Authority: GB
Inventors: Federico Velo
Original assignee: Valex International S A
Current assignee: Valex International S A
Priority date: 1999-03-30
Filing date: 2000-02-25
Publication date: 2000-09-27
Also published as: GB0004441D0; FR2790186B3; FR2790186A3; IT248099Y1; ITTV990017U1; ITTV990017V0

Abstract

A portable electric grass trimmer 4 of the type that includes a shaft 5, a main handle 6 at its upper end, a cutting device 7 at the other end, and a second handle 8 which is arranged on shaft 5 between main handle 6 and cutting device 7. The trimmer comprises a balancing member 16 which is arranged at a position close to main handle 6 and balances cutting device 7 with respect to second handle 8. In detail, member 16 is constituted by a metal block which preferably weighs 1.4 kg and is arranged in a seat formed by locators and raised portions formed inside main handle 6. The member 16 may be cement or may comprise a chamber (116 figure 4) filled with a granular material or liquid. Alternatively member 16 may be weights (216 figure 5) mounted out side handle 6 or weights mounted on or with shaft 5 (316 figure 6 and 416 figure 7).

Description

2348101 The present invention relates to a portable grass bimmer

particularly for recreational gardening.

Conventional electric grass trimmers generally include an elongated shaft which has a main handle at its upper end, a motorized cutting device, constituted by a wire or by a disk, at its lower end, and a second handle arranged between the main handle and the cutting device, In the t-hrimers having a shaft constituted by a metallic tubular segment, the main handle is constituted by a synthetic resin body comprising two half parts manufactured by injection-molding. The body accommodates the upper end portion of the io shaf in its front portion, the control push-button, in a central position, and the wiring and part of the electric components, in the rear portion. In other types of trimmers, the main handle is made integral with the shaft and sometimes with the second handle by joining two facing halves formed with the same injection-molding method. The heaviest part of the grass triinmer is constituted by the cutting device, The operator grips the main handle with one hand and the second handle with the other hand, so as to keep the tool at an angle, while the cutting device operates at ground level. It has also been found that the best performance, for example in trimming the edges of flowerbeds and the like., are achieved when the imaginary cutting plane formed by the rotation of the wire is inched at approximately 15' with respect to the ground plane.

The main drawback of the conventional grass trimmers is the fatigue of the operator caused by the unnatural worIcing position, which is in fact caused by the unbalancing effect produced by the cutting device. The left hand (in the case of a right handed person) in fact usually supports the entire tool, while the right hand pushes the main handle slightly downward in order to keep the cutting device correctly positioned. Attempts at longitudinal adjustment of the position of the second handle on the shaft are useless in this situation.

The aim of the present invention is to solve the above cited drawback of the conventional grass tri=ers by providing a portable grass trimmer wlich 2 minimizes the operator's fatigue.

An object of the invention is to provide a portable grass trimmer which is simple to manufacture, with extremely small modifications with respect to conventional grass trimmers, so as to keep the retail price low.

A finther object of the invention is to provide a portable grass trimer which requires only ordinary maintenance, for example due to wear of the cutting device.

This aim, these objects and others which will become apparent hereinafter are achieved by a portable grass trimmer comprising a shaft which supports a io main handle at one end, a cutting device at the other end and a second handle between the main bandle and the cutting device, characterized in that it comprises a balancing member for balancing the weight of the cutting device about the second handle.

Further characteristics and advantages of the invention will become is apparent from the description of an embodiment which is illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure I is a perspective view of a portable electric grass trimmer, according to the invention; Figure 2 is a sectional view, taken along a longitudinal plane, of the main handle of the grass timmer of Figure 1; Figure 3 is a sectional rear view, taken along the plane M-M of Figure 2, of the main handle of the line-type grass trimmer of Figure 1; Figure 4 is a partially sectional enlarged-scale view of the main handle of the grass trimnier wherein the balancing member is constituted by a tank; Figure 5 is a partially sectional enlarged-scale view of the main handle of the grass trimmer wherein the balancing member is constituted by a external tv weights; Figure 6 is a partially sectional enlarged-scale view of the main handle of the grass trim:mer wherein the balancing member is constituted by a weight inserted in the handle-, 3 Figure 7 is a partially sectional enlarged-scale view of the main handle of the grass trimmer wherein the balancing member is constituted by open rings associated with the handle.

With reference to the figures, the portable grass trimmer, generally designated by the reference numeral 4, includes a shaft 5, which in the illustrated case is a metallic tubular segment, a main handle 6, which is fixed to the upper end of the shaft 5. and a cutting device, comprising a cutting wire, generally designated by the reference numeral 7, at its lower end. A second handle 8 is arranged along the shaft 5, between the main handle 6 and the cutting device io 7. Conveniently, the second handle 8 can be moved longitudinally along the shaft 5 in order to allow to adapt the grass trimmer 4 to the handling requirements of the operator.

With particular reference to Figures 1, 2 and 3, the main handle 6 is constituted by two half-sheUs 9a and 9b, made of plastic, which are manufactured by injection-molding, and are joined along their perimetric by connecting means, such as screws 10.

In a front portion, the main handle 6 includes a slot 11 which allows the operator to insert his/her hand and clench it around an approximately tubular portion 12, which in turn accommodates and retains, by virtue of the screws 13, the upper end of the shaft 5 and a push-button switch 14 which protrudes into the slot 11. In its rear portion, the main handle has a slightly domed shape so as to accommodate part of the electrical components, generally designated by the reference numeral 15, and a balancing member 16 which acts downward so as to act as counterweight for the cutting device 7 with respect to the second handle 8. The balancing member 16 comprises a mass or weight, which can be a block which has a rectangular base, is slightly elongated in a vertical direction and is preferably made of metal.

As an alternative, the balancing member 16 can be a mass of c%-Ment.

Conveniently, the internal walls of both half-shells 9a and 9b are provided with an angular rear raised portion 17 and with lateral locators 18 which are 4 formed simultaneously during molding and form, as a whole, a seat for accommodating the member 16, allowing its easy assembly during production and at the same time avoiding even minimal movements thereof during use.

The many tests performed by the inventor have shown that the application of a balancing member 16 with a weight of approximately 1.4 kg best contributes to solving the fatigue problems noted with conventional grass trimrner types.

As shown in Figure 4, the balancing member 116 can also be consttuted by a container which contains a fluid material, such as a liquid, or powdery or io granular material, such as for example lead pellets. The material is introduced in the container through a bole for accessing the vessel or container 121 and the hole is preferably formed in the main handle 106 and is provided with a closure plug 120. In this manner it is possible to vary the amount of material that is introduced and therefore vary its weight and distribution, in order to is differently balance the apparatas according to the position of the central second handle along the shaft and to the operator's requirements.

As shown in Figure 5, the balancing member can be constituted by a member 216 which is external to the apparatus and is fixed, for example to the rear main handle 206, by virtue of a fixing means such as threaded members, interlocking couplings, snug-fit couplings, et cetera. The fixing means can be removable and appropriately shaped so as to avoid interfering with the ergonomics of the apparatus. Furthermore, the fixing means can Mi turn be coupled to additional members 220 so as to form a variable balancing mass, with the above described advantages.

As shown in Figure 6, the balancing member can be constituted by a member 316 which is accommodated in the upper portion of the shaft 305 instead of in the rear main handle 306. A favorable lever arm with respect to the central second handle is nonetheless provided in this manner.

As shown in FiguTe 7, the balancing member can be constituted a senies of open rings 416 adapted to be inserted in annular slots 420 provided in the shaft 405 and fastened by means of fasteners, such as screws.

For exarnple, in the case of a shaft constituted by a tube, the balancing member can be constituted by a second tube which is telescopically associated inside the first tube and is crossed by the electrical wiring.

The operation of the portable grass trimmer, with reference to the accompanying figures, is described hereinafter.

Assume that the operator supports the grass trimmer 4 with his left hand by the second handle 8 and performs the classic sweeping motion during use by gripping the main handle 6 %ith his right hand; in this case, the balancing io member 16 acts as a counterweight for the cutting device 7 with respect to the second handle 8, keeping the tool correctly tilted and relieving the operator from the unpleasant need to push the main handle 6 slightly downward.

In practice it has been found that the grass trimmer thu described achieves the intended aim and objects, since the balancing member applied to the main handle introduces only minimal aesthetic changes to the gTass trimmer. The balancing member is fin-thermore extremely flexible, since it can be applied to the entire range of portable grass trimmers. Finally, the balancing member makes the grass tri=ers to which it is applied more comfortable and effective and avoids the fatigue of the operator while improving the quality of his work.

In practice, the materials used, as well as the dimensions, may be any according to the requirements. In particular, the shape of the balancing member may be any according to the shape of the main hmcUe, 3-

Claims

6 CLAIMS

1. A portable grass trimmer, comprising a shaft which supports a main handle at one end, a cutting device at the other end, and a second handle between said main handle and said device, characterized in that it comprises a 5 member for balancing said cutting device with respect to said second handle,

2. The grass trimmer according to claim 1, characterized in that said balancing member comprises a mass.

3. The grass trimmer according to one or more of the preceding claims, characterized in that said member is accommodated in said main handle.

4. The grass trimmer according to one or more of the preceding claims, characterized in that it comprises raised portions and locators which are formed internally together with said main handle so as to form a seat for accommodating said balancing member.

5. The grass timmer according to one or more of the preceding claims, characterized in that said balancing member is constituted by a container which contains a fluid material, such as a liqiaid, or powdery or granular material, such as for example lead pellets, said material being introduced in the container through a hole for access to the vessel or container which is formed in the main handle and is provided with a closure plug.

6. The grass trimmer according to one or more of the preceding claims, characterized in that said balancing member is external to the apparatus and is fixed to the rear main handle by virtue of a fix:ing means, such as threaded members, interlocking couplings, snug-fit couplings, et cetera, said fixing means being detachable and being shaped so as to avoid interfering with the ergonomics of the apparatus, said fixing means being in turn associable with additional members so as to form a variable balancing mass.

7. The grass trimmer according to one or more of the preceding claims, characterized in that said balancing member is accommodated inside the upper portion of said shaft.

8. The grass t-immer according to one or more of the preceding claims, 7 characterized in that said balancing member comprises a series of open nings adapted to be inserted in annular slots provided in the shaft and fastened thereto by means of fasteners.