GB2027324A - A portable power tool - Google Patents

Abstract

A portable power cutting tool for cutting plants such as sugar canes, which comprises a rotary cutting blade 2 mounted on one end of an elongate tubular element 1 and driven by a lightweight engine 3 connected to the other end of the tubular element, wherein a handle 9 is mounted on the tubular element, and a pair of arm grips 14, 18 are provided for restricting the operator's arm holding the handle so as to facilitate easy manipulation of the tool with a single arm. <IMAGE>

Description

SPECIFICATION A portable power tool This invention relates to a portable power tool, and more particularly to improvements in such a portable power tool as having a cutting blade operatively mounted to one end of an elongated tubular element and driven by a lightweight engine connected to the other end of the tubular element. The portable powertool of the present invention is so designed as to be especially advantageous for reaping relatively tall plants such as sugar canes, jutes, Indian corns, soybeans or the like.

In the above-mentioned type of power tool, several models have heretofore been proposed, each of which, however, is designed so that the operator must support the whole tool with both his hands holding the two handle grips mounted on the elongated tubular element all the time that he performs a reaping operation. Although the conventional tool of this type is convenient to mow or cut grass or like relatively short plants, it is not very convenient to reap relatively tall plants such as sugar canes, jutes and so on. In fact, the above-mentioned particular type of conventional tools have scarcely been utilized heretofore in the field of reaping sugar canes, jutes or the like. The reason for it is that tall plants cut off by the cutting tool naturally fall down onto the ground in various directions.In other words, they fall and overlap one upon another, scattering in disorder, thus resulting in an obstruction in the operator's proceeding way. More particularly, in manipulation of any type of the conventional tools, the operator can not control the falling direction of tall plants just cut off because both of his hands are occupied only for holding the machine body. As a matter of course, he is not allowed to set any one of his hands free for the purpose of controlling the falling direction of cut-off plants. Thus, he has no choice in this situation but to leave the cut-off sugar canes to fall down sporadically in all directions to the ground. Consequently, the fallen plants pile up one upon another in front of the operator to block his way to advance.As a result, the operator must discontinue the operation each time he has reaped only a few pieces of canes or the line in order to put them out of the way, resulting in intolerable inefficiency. Particularly, in the reaping of sugar canes, it is necessary to cut them off at a position very close to the root because the content of sugar is the more concentrated in the lower part of its trunk. If one or more of the previously cut-down sugar canes happen to lie in front of the lowest part of trunks of the sugar canes to be cut off next, it is very difficult to cut the sugar canes at the desirable lowest part thereof. Such was one of the most important problems to be solved in the field of reaping sugar canes.

Therefore, the principal object of the present invention is to eliminate the above-discussed disadvantages and deficiencies seen in the conventional techniques by providing an improved portable power tool specially designed for conveniently reaping sugar canes, jutes or the like relatively tall plants, which permits manipulation by an operator's single hand.

According to the present invention, there is provided a portable power tool comprising a cutting blade mounted on a forward end of an elongated rigid tubular element, an engine connected directly or indirectly to the rear end of the tubular element, a drive shaft passing through said tubular element for transmitting power from said engine to said cutting blade, a handle adjustably mounted on and extending from said elongated tubular element, and arm restricting means disposed rearwardly of said handle grip and mounted on said elongated tubular element so as to extend in substantially the same direction as the handle to straddle or surround the arm of a user.

The invention will now be described further by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view showing a first embodiment of a portable power tool according to the present invention; Figure 2 is an enlarged fragmentary perspective view of the tool shown in Figure 1; Figure 3 is a top plan view of Figure 2; Figure 4 is a similar view to Figure 2, showing a modification of arm restricting means; Figure 5 is a fragmentary perspective view showing a further modification of the arm restricting means; Figure 6 is a perspective view showing another embodiment of the present invention; and Figure 7 is a somewhat schematic perspective view showing the operation by use of the reaper of the present invention.

Referring nowtothe drawings, in particular to Figures 1 to 6, wherein identical reference numerals are used throughout the various views to indicate identical elements, a portable power reaper comprises an elongate rigid tubular element 1, preferably made of metallic pipe, a rotary cutting blade 2 mounted on the front end of the rigid tubular element 1, and a known lightweight engine 3 connected directly or indirectly to the rear end thereof, wherein the power of the engine is transmitted to the cutting blade 2 through a driving shaft 4 which passes through the rigid tubular element 1.Aflexibletubular element 5 may be interposed between said rigid tubular element 1 and the engine 3, if desired, and the engine 3 may be fitted to a supporting frame 6 which has a cushion 7 and shoulder straps 8, attached thereto, so that the engine part can be carried on the operator's back in order thereby to reduce the machine weight loaded on the operator's arm. It is apparent however, that the rigid tubular element 1 may be directly connected with the engine 3, as shown in Figure 6, provided that a very compact and lightweight engine now available on the market is employed.

A handle 9 is mounted to the rigid tubular element 1, in such a manner as to extend vertically downwardly. This handle 9 is mounted on a first slide member 10 which is cylindrical in shape and is slidably mounted on the rigid tubular element 1. Preferably, the slide member 10 may be constructed so that it can be locked on the rigid tubular element 1 by means of a known locking means after having been located in a selected position most suitable to the operator.The slide member 10 as shown in Figure 2 is provided on its under side with an internally threaded socket 11, into which is screwed a threaded shaft 12 extending from the upper end surface of the handle 9 so that when the handle 9 is turned in one direction the threaded shaft 12 advances to forcibly pressing its tip portion 13 against the outercircum- ference of the rigid tubular element 1, thereby locking the slide member 10 thereon. By contrast, when the grip 9 is turned in the opposite direction, the threaded shaft 12 is retracted to release said tip portion 13 from contact with the outer circumference of the rigid tubular element 1 to allow the slide member to move freely along the surface of the rigid tubular element 1 to a new position. In such a construction, the operator can regulate the position of the handle at will even when at work.The handle 9 may be arranged so as to hang downward at right angle to the rigid tubular element 1. However, as the result of experiments, it has proven that the reaper can be more conveniently manipulated if the handle grip 9 is arranged so as to be slightly inclined toward the side of the operator.

Spaced apart rearwardly of the handle grip 9, there is provided a first arm grip or restricting means in the form of a hanging piece 14 made of rigid material such as metal and extending vertically downwardly from the tubular element 1. This hanging piece 14 has a concaved internal surface 14a to fit the curvature of the outside portion 15a of the operator's right arm 15 as shown in Figure 3. This first hanging piece 14 is fixed, for example, by welding to a second slide member 16 which is slidable along the rigid tubular element 1 as well as being rotatable about its longitudinal axis. The slide member 16 is capable of being locked on the rigid tubular element 1 by means of a known locking means 17 such as a clamp screw.Further, spaced apart rearwardly of said first hanging piece 14 there is provided a second arm grip which in the form of a hanging piece 18 is made of the same material as the hanging piece 14 and likewise extending vertically downwardly from the rigid tubular element 1. This hanging piece 18 has a concaved internal surface 18a formed to fit with the curvature of the inner side portion 1 sub (Figure 3) of the operator's right arm 15. In this connection, it should be noted that said internal surfaces 14a, 18a are concaved in opposite directions. The second hanging piece 18 is supported on a third slide member 19 which is slidable along the rigid tubular element 1 as well as rotatable about its axis in the same manner as in the case of the first hanging piece 14.This third slide member 19 is also capable of being locked on the rigid tubular element 1 by means of a known locking device 20 such as a clamp screw.

In operation, the operator first releases the handle 19 by turning it in the loosening direction and then adjusts the position of the first slide member 10 by sliding it along the tubular element 1 to the point that best suits him and then locks the slide member 10 on the element 1 by turning the handle 9 in the tightening direction. Next, the operator loosens the locking means 17, 20 to slide the second and the third slide members 16, 19 respectively, to each desired position and then rotates the slide members 16, 19 about the axis of the rigid tubular element 1 to adjust each of the angular positions of the hanging pieces 14, 18 in accordance with the size of his own arm.After setting the concaved internal surface 14a of the first hanging piece so as to matingly fit with the outer side portion 15a of his arm as well as setting the concaved internal surface 18a of the second hanging piece 18 so as to matingly fit with the inner side portion 15b of his arm, he locks the first and the second slide members 16, 19 in position, respectively by clamping the locking means 17, 20.

In manipulation of the reaper, when the rigid tubular element 1 is swung in the direction of an arrow P, the operator's forearm is apt to move away from the tubular element 1 in the opposite direction R about the handle grip 9 serving as a fulcrum as shown in Figures 3 and 7. The force developed in this stage acts effectively upon the concaved surface 14a of the first hanging piece 14 and can be converted into such energy for urging the rigid tubular element 1 in the direction P. Conversely, when the tubular element 1 is swung in the direction of an arrow Q, the operator's elbow is moved in the direction of an arrow S readily to get in contact with the concaved internal surface 18a of the hanging piece 18. Thus, the hanging piece 18 serves as a fulcrum for the swing motion of the operator's forearm, thereby promoting swinging the tubular element 1 in the direction 0.Thus, by co-operation of the two hanging pieces 14, 18, the energy loss can be minimized during the reaping operation, making the most of operator's physical force for swinging the tubular element 1 in the directions P, Q. Accordingly, the operator can perform the reaping operation quite efficiently by holding the machine body with a single arm.

Further, as can be understood from the foregoing description, the operator's left hand is free because it is not required for the job of holding the machine body. Thus, by using his free left hand, the operator can grasp and support the sugar canes while cutting, so that they are prevented from falling down in unexpected directions before having been cut-off to the last skin as well as from being incompletely cut.

More importantly, the reaper enables the operator to regulate the falling direction of the cut-off plants by using his unoccupied left hand in order to prevent the cut down plants from being piled up in disorder in front of him, eliminating the disadvantages seen in the conventional portable power cutting tools having an elongated tubular element.

Figures 4 and 5 illustrate alternative embodiments of the present invention, wherein the first and the second hanging pieces 14, 18 are formed integrally as part of a 'U' shaped member (Figure 4) or a tube (Figure 5). More particularly, in the modification shown in Figure 4, both of the hanging pieces 14 and 18 are secured to the second slide member 16.

While, the modification of Figure 5 has a hollow cylindrical member, whose one sidewall 14 is utilized as the first hanging piece and the other side wall is utilized as the second hanging piece 18. In these embodiments, the third slide member 19 is not required. The operational manners of the two mod ifications are substantially the same with the preceding embodiment already fully described. Reference numeral 21 designates cushion layers made of foamed synthetic resin, rubber or like soft material and adhere to the internal surfaces of the first and the second hanging pieces 14, 18. These layers 21 may be provided, if desired, for the purpose of decreasing the vibrations transmitted to the operator's right arm as well as preventing the operator from feeling pains in his right arm which is engaged in the hanging pieces 14, 18.

Figure 6 shows another embodiment of the present invention, wherein the basic construction thereof is substantially the same as that of the preceding embodiment shown in Figures 1 to 3, except that the rigid tubular element 1 is connected directly with the engine 3 and that a friction layer 22 is fixedly secured on the tubular element 1 in position near the engine 3. The friction layer 22 may preferably be made of foamed plastic, rubber or like material having a surface of high friction coefficient. The friction layer is provided for the purpose that the operator can easily hold the elongated tubular element 1 under his arm.

The provision of the friction layer is very advantageous especially in such embodiment as illustrated in Figure 6 wherein the portable power reaper is so constructed that the engine part cannot be carried on the operator's back.

Claims (12)

1. A portable power tool comprising a cutting blade mounted on a forward end of an elongated rigid tubular element, an engine connected directly or indirectly to the rear end of the tubular element, a drive shaft passing through said tubular element for transmitting power from said engine to said cutting blade, a handle adjustably mounted on and extending from said elongated tubular element, and arm restricting means disposed rearwardly of said handle grip and mounted on said elongated tubular element so asto extend in substantially the same direction as the handle to straddle or surround the arm of a user.

2. A portable powertool as claimed in Claim 1, wherein said handle is detachably connected to a first member which is slidably mounted on said elongated tubular element.

3. A portable power tool as claimed in Claim 1 or 2, wherein said handle is inclined toward said arm restricting means.

4. A portable power tool as claimed in Claim 1,2 or 3, wherein said arm restricting means comprise a pair of pieces spaced along the axis of the tubular element.

5. A portable power tool as claimed in Claim 4, wherein one of the pieces constituting the arm restricting means is secured to a member which is slidably mounted on said elongate tubular element.

6. A portable power tool as claimed in Claim 5, wherein the other of the pieces constituting the arm restricting means is secured to a further member which is slidably mounted on said elongate tubular element.

7. A portable power tool as claimed in any of Claims 1 to 3, wherein the arm restricting means comprise a 'U' shaped member secured to a member slidable along the elongate tubular member.

8. A portable power tool as claimed in any of Claims 1 to 3, wherein the arm restricting means comprise a tube secured to a member slidable along the elongate tubular member.

9. A portable power reaper as claimed in any preceding claim, wherein the arm contacting surfaces of said arm restricting means are concave.

10. A portable power tool as claimed in any preceding claim, wherein said arm restricting means includes a cushioning layer adhered to the internal surface thereof.

11. A portable power tool as claimed in any preceding claim, wherein said elongated tubular element is provided with a friction layer engageable under a user's arm.

12. A portable power reaper substantially as herein described, with reference to and as illustrated in any of Figures 1 to 6 of the accompanying drawings.