The subject invention refers to a handle unit for a handheld working tool, such as a chain saw, cutting machine or hedge trimmer, and the working tool comprises a drive unit with an engine and a cutting unit, such as a guide bar with saw chain, cutting disc or shears. The handle unit comprises two mutually associated hand grips, which, at normal use of the working tool, are located higher up than the drive unit, which is rotatably mounted to the handle unit, so that the cutting direction of the cutting unit while rotating is being changed in vertical to horizontal direction. At least one attachment frame is mounted to the drive unit, and the handle unit is arranged with at least one handle support intended for detachable attachment in different positions along the attachment frame.
As a rule handheld working tools, such as chain saws, power cutters and hedge trimmers, have a rear handle with a throttle control as well as a front handle frame extending around most part of the drive unit. In this manner the operator would be able to hold the front handle frame in many different positions, thus simplifying cutting work both in horizontal and vertical direction. DE 2909777 describes a chain saw having a laterally rotatable front hand grip. Hedge trimmers equipped with a laterally rotatable rear handle are known. These features can of course simplify handling of the tool but does not solve another basic ergonomical problem, e.g. a great deal of cutting work must be done near the ground or floor, such as felling a tree with a chain saw, cutting a concrete pillar with a power cutter or short-cutting a hedge with a hedge trimmer. At this kind of work the operator often has to crawl on the ground to be able to manage the tool.
In the russian forestry there exists a number of chain saw models having an especially high level handle. The handle has two mutually associated hand grips located equally abreast and high above the saw. The space between the hand grips corresponds to the operator's breadth across the shoulders, approximately. The saw itself is rotatable in relation to the handle between a felling position and a cutting position. SU 1006220 and SU 1085818 both describe examples of such solutions having an attachment frame, which is sprung suspended and partly surrounding the drive unit. The handle is mounted to the attachment frame with a handle support, which can be pushed along the attachment frame in order to provide the rotatability of the saw. On the other hand the both highly located hand grips are completely without any engine control, which obviously is a very severe disadvantage. The operator could thus be standing upright felling or cutting a tree. On the other hand the high handle could be clumsy to use at tree limbing work, however, in the russian forestry as a rule the trees are taken to a centrally stationed machine for automatic limbing. SU 880717 and SU 1117210 both describe chain saws with a high handle, which is mounted so that the saw can be used only in a felling position. The latter is arranged as an accessory to a conventional saw. Both have a throttle control in connection to one hand grip. However, the cable from the throttle control is lead completely unprotected down to the drive unit. For that reason it becomes sensitive to damages in the hard work environment where these products are used. Another type of saw has a pivot located entirely behind the drive unit. But since this pivot is located entirely behind the saw body with its drive unit and projecting guide bar, substantial strains will arise in this pivot. It therefore has to be substantially dimensioned and thus necessarily protrude a lot behind the very saw body. This is disadvantageous since the protruding pivot as well as the handle down to the pivot tend to end up between the operator's legs and thus come into conflict with these. Simultaneously, substantial strains will as well arise in the handle, so that this also has to be substantially dimensioned.
The purpose of the subject invention is to substantially reduce the above outlined problems, and to achieve advantages in many respects.
The above mentioned purpose is achieved in that the handle unit in accordance with the invention is having the characteristics appearing from the appended claims. The handle unit, according to the invention, is thus essentially characterized as appearing from the appended claims. Accordingly, the down-projecting part extends down at the rear side of the drive unit and gives protection to the engine controls. For, generally the drive unit is arranged with a warm side having a muffler, which lets the exhaust gases out at the cutting side, as well as a cold side facing the operator. As a rule carburettors and similar parts are arranged at the cold side and the engine controls connect here. On a modern anti-vibrated working tool preferably this takes place in the vibration gap, which is arranged between the anti-vibrated part and the engine supporting part. For that reason said down-projecting part extends down at the rear side, and leads the engine controls almost right up to the vibration gap. The handle unit could also be provided with a fuel tank. In that case its fuel hose is drawn so that it becomes protected by the down-projecting part. These and other characteristic features and advantages will become more apparent from the following detailed description of various embodiments with the support of the annexed drawing.
The invention will be described in closer detail in the following by way of various embodiments thereof with reference to the accompanying drawing figures.
In figure 1 numeral reference 1 designates a handle unit for a working tool 2, in accordance with the invention. The working tool comprises a drive unit 3 with an engine, and a cutting unit 4, which in the shown example is a guide bar 4 with chain, since the shown tool is a chain saw. However, when the working tool is a power cutter the cutting unit 4 would be a cutter disc, or, when the tool is a hedge trimmer the cutting unit would be shears. The cutting unit 4 is shown by dash-dotted lines since it is only one of many conceivable examples of a cutting unit connected to the drive unit 3. Other examples than the given ones are of course possible. The cutting unit protrudes from a cutting side 11 of the drive unit. This side is opposite to a rear side 10 facing against the operator.
The cutting unit 4, in this case a guide bar, has a cutting direction according to arrow 16, i.e. in level with the paper in figure 1. In figure 3 the drive unit 3 and thus the cutting direction 16 have been turned approximately 90 degrees in relation to the handle unit 1. For, an advantage with this kind of solution of handle is that the operator can be standing upright in a natural working position at the same time as the cutting unit 4 is working near the ground in a suitably selected cutting direction 16. As mentioned, the intended work could be felling a tree, cutting a concrete piller or short-cutting a hedge. Chain saws with such kind of high level handle have been used since a long time in the russian forestry. However, the subject invention illustrates a particularly advantageous method of arranging transfer of engine control by having an advantageous design for the handle unit's mounting onto the drive unit of the tool.
At least one attachment frame 7 is mounted to the drive unit and serves as attachment of the handle unit. The handle unit is provided with a handle support 8. This is designed as a clamp holder, thus surrounding the attachment frame 7 and riding this. The handle support has a clamping screw 21, which the operator can untighten when he wants to turn the drive unit, and then tighten again when he wants to lock the drive unit in another angular position. ) Preferably the clamping screw has a large and easily managed knob, which can be turned even when using working gloves. Other types of quick locks are of course also conceivable, e.g. locking with an eccentric or with one or several quick clamps. As becomes apparent from figure 2 the attachment frame 7 is mounted onto something that according to the figure is an underside and a left side of the drive unit. Hereby it becomes possible for the handle support 8 to be pushed along the attachment frame 7, so that a rotation of haughtily 90 degrees is created.
The embodiment of the invention that becomes apparent from the figures 1-4 offers a particularly simple and durable mounting of the handle unit. A rear attachment cooperating with the handle support 8, such as a pivot, is arranged, partly in the handle unit as a rear attachment 12 and partly in the drive unit as a rear drive unit attachment 13 arranged at the rear side 10. Compare figure 1 and 4. The handle unit is thus leading down to a rear attachment 12 arranged as a pivot. The rear attachment 12 is arranged in a down-projecting part of the handle unit and is preferably composed of a piece of flat metal bar with a hole. A screw 14 is inserted through this hole and into a threaded hole 22 in the rear drive unit attachment 13. Preferably a bushing 15 is placed between the rear drive unit attachment 13 and the rear attachment 12 in order to counteract wear of the parts. In figure 4 an imaginary axis of rotation 23 has been marked. It runs through the centre of the rear drive unit attachment 13 as well as the centre of a radius R. For, the attachment frame 7 preferably over a large part of its length has an essentially circular form, with a radius R, in order to simplify rearrangement of the handle support between the different positions along the attachment frame. This will simplify rearrangement of the handle support, but is not an absolute precondition. The handle support 8 can also be designed in many different ways not requiring any circular form of the attachment frame 7, e.g. the handle support 8 could be fully or partly open so that the attachment frame can be displaceable inside the handle support 8, e.g. if a more angular shaped frame had been used.
Many drive units 3 run by an internal combustion engine are comprising an anti-vibrated part 17 mounted to an engine supporting part 18 by means of anti-vibration elements 19. The engine supporting part is then mounted to one end of each anti-vibration element 19 respectively. Thereby the both parts are joined solely by these anti-vibration elements, which means that the vibrations in the anti-vibrated part could be reduced substantially compared with the vibrations in the engine supporting part. For example, on a chain saw usually the handle frame and the rear handle are mounted to the anti-vibrated part. In figure 4 is shown how the attachment frame 7 is mounted to the anti-vibrated part 17. Furthermore the rear drive unit attachment 13 is arranged in the anti-vibrated part 17. In this manner the handle unit 1 will thus become anti-vibrated in relation to the engine unit. This anti-vibration will of course improve the user-comfort considerably for the operator. However, simultaneously there exist handheld working tools run by internal combustion engines, hydraulic engines, pneumatic engines or electric engines, having no kind of anti-vibration at all, and anti-vibration is of course no precondition for the invention.
The down-projecting part 9 extending down at the rear side 10 of the drive unit is used for giving protection to engine controls, such as a throttle cable, or an electric cord for stop control, leading from at least one of the hand grips 5, 6 to the rear side 10 of the drive unit. For, usually the drive unit 3 is arranged with a warm side having a muffler, which lets the exhaust gases out at the cutting side 11, as well as a cold side with a rear handle used by the operator. As a rule carburettors and similar parts are arranged at the cold side. It means that the engine controls are generally lead in at the cold side. On a modern anti-vibrated working tool preferably this takes place at the vibration gap arranged between the anti-vibrated part and the engine supporting part. It is therefore important that the down-projecting part 9 extends down at the rear side 10, and leads the engine controls almost right up to the vibration gap. The handle unit 1 could also be equipped with a fuel tank. In that case its fuel hose preferably is drawn so that it becomes protected by the down-projecting part 9. In the shown embodiment the handle unit as seen from the side of the operator, i.e. from the rear side 10, is shaped as a V and having its top point down at the rear attachment 12 and its upper ends at each hand grip 5, 6 respectively. It is therefore natural to lead engine controls from the left hand grip inside the left tube, and engine controls from the right hand grip inside the right tube. It is also natural to lead a fuel hose from a possible fuel tank at or inside one of the tubes. The branches of the shaped V are stabilized by a cross bar 26. Two bars 27 and 28 support the handle support 8. By this geometry the strains in different directions will be taken up very efficiently, so that a light and strong handle unit is created. The handle itself could be made of aluminium or magnesium, while the attachment frame 7 could be made of steel. Because they are combined with a fastening clamp or screw. As becomes apparent from figure 1 the drive unit attachment 13, the rear attachment 12 and the down-projecting part 9 protrude only a little behind the drive unit. This is due to the cooperation between the handle support 8 and the rear attachment, which is very effective and gives less strains.
Normally the hand grips 5, 6 are located beside each other approximately with a shoulder-breadth between them. But obviously the handle unit could be made adjustable both vertically and horizontally.
The attachment frame, according to figure 4, is composed of three different parts, a frame part 29, which in the actual case is made of a steel tube with a diameter of 22 millimetres and a material thickness of 1½ millimetres. At its lower part it is welded onto a bottom attachment part 24, in this case a flat iron bar mounted to the underside of the anti-vibrated part. At the other end the frame part 29 is welded onto a side- attachment 25, which in this case is made of a flat iron part and fastened onto the side of the anti-vibrated part 17. The bottom attachment 24 has in the shown case two shackles offering a wide mounting base onto the anti-vibrated part 17. However, in many applications it would be sufficient to have only one bottom attachment in the anti-vibrated part, e.g. the bottom attachment could then be made of a flattened part from a longer metal frame. In such a manner could also the side-attachment 25 be arranged. Furthermore, the whole frame could be cast from a plastic material, either homogeneously or with cast hollow spaces. Often the frame part 29 has a round cross-section, usually in form of a round tube. The cross-section could be completed with at least one protruding part for improving transfer of rotation between the attachment frame 7 and the handle unit 1. The protruding part could consist of a ridge, which protrudes from the periphery of the cross-section. This is particularly important if the cross-section is round and the attachment frame alone shall support the drive unit. The frame part 29 could also have an oval or a square or another cross-section, which will counteract rotation between the handle support 8 and the frame part 29. And the cross-section could either be homogeneous or tube-shaped. The attachment frame 7 could also over most part of its length be arranged as a double frame, i.e. two mutually parallel frame parts cooperating with the handle support 8. For example, two frame parts 29 could be arranged beside each other and mounted to the bottom attachment 24 and the upper attachment 25. The handle support 8 could then be riding both these frame parts 29 and the arrangement would ensure a satisfactory support of the drive unit, even if a rear attachment should be missing.
Figure 5 thus shows an adjustable handle unit provided also with a fuel tank. The hand grips 5,6 are arranged around handle tubes 37,38, which extend down in the down-projecting part 9, and the engine controls, and a possible fuel hose, are preferably attached to the down-projecting part by being inserted inside at least one of the handle tubes. Engine controls, such as a throttle cable, an electric cord for stop control or a possible fuel hose, are mounted to the down-projecting part 9, except for at the lowest part of the down-projecting part, where they instead pass over to the drive unit, e.g. by passing in through the vibration gap. Preferably they pass over from the inside of the handle unit so that they become well protected at the changeover. The engine controls and a possible fuel hose could also be mounted onto the outside of the down-projecting part and thus be protected. This is particularly advantageous if the handle tubes are provided with one or several grooves for this purpose.
The handle tubes 37,38 extending down in the down-projecting part 9 are essentially arranged and shaped as a V, and are upwards and downwards adjustable, so that during raising the height of the handle unit will increase, as well as the distance between the hand grips 5, 6 will increase. This is achieved in that the handle tubes are displaceably attached, partly into a bottom attachment 39 and partly in a cross bar 41. Both these are designed so that they surround the handle tubes, e.g. U-shaped, and are clamped together around the tubes by means of screws. Hereby the tubes could be raised or lowered in order to suit different operators. At a raising also the mutual distance between the hand grips will increase. Because longer persons are often more broad-shouldered. However, the hand grips could preferably as well be turned somewhat thus altering the distance between the hand grips and their angling. The V-shape of the handle unit, as seen from the view of the operator, is thus offering obvious advantages with respect to adjustments, as well as to stability and low weight. The cross bar 41 is supporting the bars 27 and 28, compare fig. 2, as well as the fuel tank 36.
The bottom attachment 39 is in this case provided with a rear attachment 12 for mounting onto the drive unit, as earlier described. The bottom attachment 39 also serves to attach a supporting shield 40, intended to cooperate with the operator's legs. It therefore has a comfortably vaulted form, so that the operator could rest either of his legs against it. The supporting shield 40 could also form part of the attachment 39.