DE4019894A1 - Hand held electric power tool with pistol grip handle - has motor and main weight concentrated in handle with short tool spindle for improved location and drive control via geared transmission - Google Patents

Abstract

The electric power tool is of pistolgrip type with a main housing (11) for accommodating the motor (13) with its electrical connections (21) and a secondary housing (12) providing the tool spindle (13) support with bearings. A geargo drive coupling (15a,22) between motor shaft and spindle (13) is housed in the head of the unit (11a) integral with the main housing (11). An external ring type on-off reversal switch (20) surrounds the housing (11) and speed contro via suitable electronic circuitry is provided by rotary potentiometer (21a). ADVANTAGE - Short length and small diameter of tool spindle housing is more convenient to locate and use than others where motor is positioned in this housing, fatigue effects on operator's wrist due to reactive torque and overhung weight are minimised.

Description

State of the art

The invention is based on an electric hand tool according to the preamble of claim 1.

Electric hand tools with the usual pistol hand handle housings are known in many forms (e.g. DE-PS 28 17 814 or DE-OS 31 03 286); such devices become comprehensive for screwing, drilling, impact drilling u. Like. Used and are always constructed so that to the rear part of one in the axial direction tion of the tool spindle extending main housing a roughly right angle or slightly obtuse running handle is attached so that the gan ze housing of such an electric hand tool about one pistol-like shape.  

There are the drive motor, a given if available gear, gear changeover means and the tool output spindle in the usually barrel mig or oval-shaped main housing, while the one starting from this and usually in one piece attached to the plastic shells of the main housing Handle electrical switching means, wiring, Control modules for speed, switching on and off or Reversal of rotation contains, but mostly via ver equally free space, while the rest components of the electric hand tool in the hori zonal main housing rather crowded are arranged. Such an arrangement of the device components ten also has good reasons for the fact that the match drive motor shaft and tool spindle Gearbox construction apparently simplified, and powerfully built main housing, which usually consists of a Injection molded part made of suitable hard plastic, can also perform sub-tasks for tool shafts, gearboxes be and drive motor. It is in this too connexion also known areas of the main housing instead of using certain engine parts at for example on one or both motor plates breed and if necessary the rotor directly in To accommodate bearing recesses in the main housing. Electric hand tools can do this general Best pistol grip shape from two identical half shells hen, with the individual Ge in a first half-shell device components are used pre-assembled, while the second half-shell then serves as an end cover. However, it is also known, especially among profigers  ten, the main housing as a single closed To manufacture pipe part from one piece.

The disadvantage that comes with electric hand tools this structure is that the hand of the User necessarily and sensibly the work grips at its rear end where the Pi stolen grip goes off at an obtuse or right angle, so the tool due to the considerable weight one turn in the horizontal main housing around the handle part moment and has a tendency to move forward tilt. The user of such a tool is therefore required to keep this level when working against the constant tipping moment so that rapid Fatigue occurs in the user's wrist and therefore one has already tried, especially with machines at the front end in the area of the tool neck to arrange a handle that protrudes transversely, so that it is possible to close the device with both hands handle.

Such an ambidextrous way of working is with Schrau ber or other lighter devices unusual, also because the operator in the free Hand usually holds a screw supply in order to faster working after screwing one Screw on the next screw on the tool close and screw in the screw.

Another disadvantage with the known pistol grip Electric hand tools usually consists in that  the horizontally running main housing part often very long builds or must build so that all components under can be brought, although in the handle itself there is sufficient space - but on the other hand not can be made smaller because it is at least as large must be that it is securely gripped by the user's hand can be. There are inevitable disadvantages regarding the optimal use of space. The devices are usually larger than this in terms of the enclosed ones actually available Space would be required.

The invention is therefore based on the object an electric hand tool in the shape of a pistol to ensure that this is flawless and without development a tilting torque in the hand is at the same time optimal use of the available Space.

Advantages of the invention

The invention solves this problem with the mark the features of claim 1 and has the advantage that it due to the arrangement of the drive motor in hand handle is possible, the external dimensions of the device the same equipment and performance to reduce considerably not only a much smaller space may means, but at the same time optimal Utilization of the available space assembly and manufacturing costs, including in scope  of the required material significantly reduced.

Another significant advantage with the present Er Invention is that when the user the handle of the pistol-like device captures virtually the entire weight of the device it is embraced, so that in addition to that anyway weight to be carried by his hand and arm not always against that even when idle developed by such a pistol grip device Fight tilting moment forward down.

In one embodiment of the invention, this order was still optimized in that it is possible without any problems is above the part housing in the handle below brought drive motor which is also a considerable weight of other gear parts, ins special for torque redirection to accommodate so that the gearbox weight in the vertical axis downwards, which acts completely without tilting moment a particularly easy and unproblematic handling of the device.

Such a device structure is particularly for one Screwdriver cheap because the user is not constantly between between the various acting forces balancie ren must and is also able, due to the very short and light building horizontal ge part of the house in which the tool spindle is mounted is also very close to the actual place of work to arrive, so that any canting, the  Work occurs unconsciously, not immediately to one Guide the screw to be set.

It is also advantageous that the immediate vicinity of the Drive motor to the naturally the handle housing partially supplied electrical lines or in Handle housing part at a suitable location brought accumulators or batteries longer wiring make exercises redundant; in particular it is on the possible with highly integrated circuits, occupy the smallest space, immediately the electri make connections to the drive motor where with a particularly suitable design the invention consists of the drive motor to train, as in the German utility model G 89 08 646.5, whose priority is claimed, be is written.

With this electric drive motor, one is the carbon brush and their brackets are more load-bearing to predetermined ones Angular amounts of relatively rotatable switching ring pre -eseed hen, the field windings of the Stator and the armature windings each different polarity reversal switches in one middle position the off position of the on drive motor marked and with an outer, manual actuatable adjusting ring on the handle housing part ver is bound.

This makes it possible to twist one Type of rotation switch on the handle of the device the same  to determine its electrical functions in good time and to be specified, possibly supplemented by further scarves ter or knurled wheel potentiometer for speed control.

By further measure listed in the subclaims are also advantageous training and Improvements of the electric specified in claim 1 hand tool possible.

The arrangement of a rotatable is particularly advantageous mounted bevel gear above the protruding outward Stub shaft of the drive motor, so that both are together combing and with the bevel gear simultaneously in another tooth in an axial-horizontal direction wreath on his face, the dome lung claws forms with an axially displaceable second coupling part depending on the axially displaceable Position of the tool spindle for driving it in Connect actively.

Finally, it is advantageous that the pistol handle arranged drive motor a completely abge in itself represents a closed and independent unit with own bearing of the rotor shaft on both sides in A and B end shields each, which can be are held together and between them the stator Center the package. In this respect, the invention goes against the previous developments in this area reverse path, however, a variety of advantages provided by the housing of bearings and centering gave for corresponding device components, including gears  be relieved and the like and in any case the An drive motor as completely pre-assembled, adjusted and independent unit in the handle housing part brought. It is therefore also possible, at least to form this housing part closed in a tubular shape and push the drive motor in as far as it will go, in which position the output shaft stub of the An drive motor in operative connection with the above the Motor arranged bevel gear arrives.

drawing

Embodiments of the invention are in the drawing tion and are described in the following section spelling explained in more detail. The drawing shows Sche on average, an electric hand tool with An drive motor in the handle housing part in the preferred Embodiment of a screwdriver.

Description of the embodiments

The basic idea of the present invention is the previous building trend for electric hand tools say reverse and when arranging the drive motor in the handle part of the case with this übli Chen design of a pistol grip electric hand tool horizontal housing part in dimensions small and rather petite to keep, so practical the entire working components of the electric hand tool  gather in the handle housing part and its horizon taler narrow, forward-facing approach as second Housing part only serves the tool spindle of the device, if necessary, some more Gear parts, also for torque limitation or similar to record.

In the drawing, the electric hand tool is shown as a screw 10 , although it is understood that the basic principle of the present invention can also be applied to other electric hand tools with different functions, which have the usual pistol handle shape, such as hand drills, impact drills and the like. the like

The main component of the housing here is a substantially tubular-cylindrical handle housing part 11 , which forms a head part 11 a at its upper end region, from which in the horizontal direction in the drawing plane to the left another, if desired, also one-piece housing part 12 goes out, which is little more than an approach of the head part 11 a bil det and mainly serves to form the second bearing for the tool spindle 13 , which is shown in the drawing only indicated with its right end region and also, if desired, one adjustable depth stop for the respective screw depth.

The inserted in the handle housing part 11 elec tric drive motor is designated 13 ; it represents a self-contained unit with bilateral end plates 13 a, 13 b, which the rotor shaft bearings 14 a, 14 b for the rotor shaft 15 bil. The two end shields 13 a, 13 b are clamped 16 with each other and take centered between them the stator 17 . On the fan wheel 18 opposite side of the drive motor 13 there is a ver rotatable brush support plate 19 by predetermined angular amounts; the brush holder plate 19 allows in their training as a switching ring according to the description in the mentioned Ge usage pattern G 89 08 646.5 reversing the direction of rotation of the electric motor by brush adjustment and switching on / off, so that a mechanical connection between the switching ring / brush holder plate 19 and an outer Setting ring 20, the setting of the desired electrical function of the drive motor is possible.

The collar 20 is mounted in the illustrated embodiment, for example, on the outside of the handle housing part 11 of the electric hand tool; it can, for example, be guided in circumferential grooves and be secured against axial displacement and is mechanically connected to the inner switching ring 19 . It is therefore possible to snap on the outer adjusting ring 20 by arranging suitable latching and retaining lugs on the handle housing part and thereby simultaneously producing the mechanical connection with an actuating lever protruding through a housing in the form of a slot, which is connected to the switching ring 19 . Alternatively, however, it is also possible to mount the adjusting ring 20 , which in this respect forms a rotation switch, as an inner, even partial ring in the handle housing part and to enable it to be actuated through a slot from the outside. This also makes it possible to keep the handle free of other, outwardly projecting switching elements, for example on / off switch u. Like., Which could easily be perceived as annoying.

In the lower free space 11 b of the handle housing part 11 , if desired, further electrical circuit components can be arranged, for example a speed control circuit 21 , if further desired with an externally actuatable control potentiometer 21 a.

The rotor shaft 15 , which projects upwards with a stub shaft 15 a, meshes with a bevel gear 22 of a deflection gear; the bevel gear 22 is rotatable, but axially immovable expediently mounted on a suitable bearing (needle bearing 23 ) on the rear part of the tool spindle 13 . The tool spindle 13 is itself supported by a further fixed bearing 24 , which can also be a needle bearing, but is arranged axially displaceably, the two respective axial end positions in the drawing above and below the tool spindle center line being recognizable. These designs specifically meet a screwdriver training, in which a first coupling part 25 is rotationally fixed and also axially immovably connected to the tool spindle 13 , so that when the tool spindle is pressed backwards by applying a screw against a corresponding spring preload, this coupling part 25 with its rearward-facing claw ring 25 a is in operative connection with a counter-claw ring 22 a as an integral part of the bevel gear 22 . In this way, the mechanical operative connection between the drive motor output shaft and the tool spindle is established.

It is understood that this is only a possible embodiment of the invention, which is specially tailored to a screwdriver function and in which the handle above the drive motor in the hand housing part head 11 a arranged deflecting gear at the same time in a corresponding extension as a separating clutch for the screwdriver function is inserted. Further configurations are possible here; in particular, a reduction gear can be arranged in the horizontally extending housing shoulder 12 as the second housing part if the electric hand tool 10 is used as a hand drill - it is also possible to integrate percussion drilling functions in the area of the deflection gear.

It can be seen that the main housing part in the electric hand tool of the present invention is actually the handle, the upper head part 11 a (one piece) is connected to the drive motor 13 bearing tube part that suitable, inwardly curved niches or support surfaces 26th benge in the transition, which particularly serve a strong pressing of the tool or screwdriver without the user's hand slipping. These holding niches 26 are also so high in the transition between the handle-housing part and its head arranged that the transmitted force is practiced practically in the plane of the desired screw action.

It is understood that in the handle housing part suitable cross walls, locking lugs, ribs u. The like. Are arranged, of which only one is shown at 27 and which serve to secure the drive motor axially and radially in the handle housing part.

It can all in the description, the claims and the drawing features shown both individually and in any combination with each other be essential to the invention.

Claims (8)

1.Electric hand tool, in particular screwdriver, hand drill, hammer drill or hammer, the sen housing from a pistol handle and an angular (in one piece) attached to it, the tool spindle accommodating further housing part be, also with a stator, end shields and rotor with rotor shaft Existing drive motor for the tool spindle, characterized in that the drive motor ( 13 ) within the housing part forming the pistol handle ( 11 ) is received and between the drive motor output shaft stub ( 15 a) and the tool spindle ( 13 ) a the torque output 90 ° deflection of the gear ( 22 ) is arranged. 2. Electric hand tool according to claim 1, characterized in that the handle housing part ( 11 ) consists of a tubular / cylindrical main part and an integrally attached to this top head ( 11 a), in which the deflection gear ( 15 a, 22 ) is arranged is such that essentially the entire weight of the electric hand tool is centered free of a tilting torque effect in the handle area. 3. Electric hand tool according to claim 1 or 2, characterized in that from the head ( 11 a) of the handle housing part ( 11 ) horizontally starting a white housing part ( 12 ) forming approach is provided, which is above the level of the handle housing part ( 11 ) also forms a first bearing for the tool spindle ( 13 ), the second bearing of which is arranged in the region of the steering gear ( 15 a, 22 ). 4. Electric hand tool according to one of claims 1-3, characterized in that the deflecting gear is formed by a bevel gear ( 22 ) which meshes with the obliquely at an obtuse angle stub shaft ( 15 a) of the rotor shaft ( 15 ) of the drive motor ( 13 ) and in turn forwards the absorbed torque to the tool spindle ( 13 ). 5. Electric hand tool according to one of claims 1-4, characterized in that the drive motor has its own housing (bilateral end plates 13 a, 13 b) with the rotor shaft ( 15 ) carried by the rotor centering bilateral bearings ( 14 a, 14 b) and against axial and radial stops for securing against displacements in these directions in the inner tubular shape of the handle housing part ( 11 ) is inserted or inserted. 6. Electric hand tool according to claim 5, characterized in that the electric motor has an inner, brush-bearing switching ring ( 19 ) which is in mechanical rotary connection with an outer switching ring on the handle housing part ( 20 ) such that by rotating the outer adjusting ring ( 20 ) the direction of rotation and / or the on / off mechanism of the drive motor can be actuated. 7. Electric hand tool according to one of claims 1-6, characterized in that in the form of a screw bers the bevel gear ( 20 ) as the main gear part of the deflecting gear at the same time part of an axial separating clutch (dog clutch 22, 25 ) for the tool spindle ( 13 ) , the torsionally and axially immovable Lich with its own axial displaceability against spring tension a first coupling part ( 25 ) with claw toothed ring ( 25 a) which is opposite a corresponding claw toothed ring ( 22 a) on the bevel gear ( 22 ). 8. Electric hand tool according to one of claims 1-7, characterized in that in the lower region of the handle housing part, electrical circuits and wiring are arranged immediately adjacent to the brush area of the drive motor ( 13 ).