Handle for a hand-held power tool

A hand-held power tool including a tool spindle (12) having a motor (6) for driving the tool spindle (12), a handle (18) having a forwardly inclined position in which the handle (18), starting from the spindle axis (W) is inclined, at least for a most part, in an operational direction (A) of the power tool (2), and an actuator (22) provided on the handle (18) for switching the motor (6) on and off.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to hand-held power tools such as, e.g., motor-driven screw-driving, drilling, and chisel tools, in particular to drills, hammer drills, rotary-percussion tools, battery-driven screw-driving tools having each a handle, in particular, a pistol grip-shaped handle having an ergonomical curvature and inclined over its longitudinal extent, for the most or completely, with respect to the spindle axis of the power tool, with an actuator for switching the motor on and off being mounted on the handle.

2. Description of the Prior Art

Handles, which are inclined relative to the spindle axis, proved themselves over the years as optimal handles for motor-driven hand-held tools. Mostly, the handles have a shape of a pistol grip. The later has a curvature adapted to a human hand. Such handles can constitute a component of all possible handle shapes such as spade handles, T-handles, or be provided thereon. German Publication DE 33 41 823 discloses a handle of an electrical tool with a pistolet-shaped switch handle. The handle forms with the spindle axis of the tool an angle of about 100° in the operational direction of the tool. As a result, with a conventional work in the direction of a wall, a ceiling, or a floor, the forearm axis and the spindle axis are substantially parallel to each other. The switching of the motor on and off is effected, with a conventional position of the hand on the handle, with the fore-and middle fingers. In addition, there is provided an auxiliary handle, with which at a conventional operation of the tool, the forearm axis and the spindle axis extend substantially coaxially with each other, and the switching of the motor on and off by actuating the actuator is effected with the small and ring fingers.

With the known arrangement of the pistol-shaped switch handle, in the majority of applications, optimal guidance and transmission of force from a tool operator to the tool becomes possible.

A drawback of the known switch handle consists in that with, e.g., working a wall in the vicinity of a floor, in particular, during mounting of skirting boards, the hand of an operator grips the handle in the ergonomically most unfavorable position. This consists in that with such use of the tool, often the handle, together with the handle-holding hand, occupies a position which is directly opposite the position of the handle at normal uses. Moreover, in such cases, the actuation of the actuator is rather difficult as the actuator is not located any more in the region of the fore-and middle fingers but rather in the region of the small-and ring fingers.

Accordingly, an object of the present invention is to eliminate the foregoing drawbacks in hand-held power tools such as screw-driving, drilling, and chisel tools.

Another object of the invention is to provide a hand-held power tool with a handle which would insure a convenient operation of the tool in corner regions between a wall and a floor.

SUMMARY OF THE INVENTION

These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a handle that has a forwardly inclined position in which the handle, starting from the spindle axis, i.e., in the direction of its longitudinal extent, is inclined, at least for the most part, relative to the spindle axis, in the operational direction of the tool. Thereby, a hand of an operator occupies an ergonomically favorable position in applications, such as working the corner region between a wall and a floor, when the handle is pivoted by 180° with respect to the normal position of the handle during a conventional wall operation of the tool. The power tool is held so that the spindle axis lies beneath the handle and in a position in which it is closest to the small finger of the operator hand holding the handle. With this position, the spindle axis is located closely to the floor or bottom, and the handle is conveniently held by the operator. The convenient holding is achieved as a result of the forearm axis of the operator and the spindle axis of the tool extending parallel to each other when the tool is pivoted about the spindle axis by 180° with respect to its normal position.

In accordance with a preferred embodiment of the present invention, the handle is pivotable between its forwardly inclined position and its normally inclined position in which the handle starting from the spindle axis, is inclined, at least for the most part, in a direction opposite the operational direction of the tool. This permits to use the tool in any desirable application, for normal operation on walls, floors, and ceilings and for operation in corner regions, in particular between a wall and a floor. In this way, the operator's hand always occupies an ergonomically optimal position in each possible application.

Advantageously, the balancing axis of the handle forms an angle in a range from 10° to 40°, in particular, an angle of 30°, between the forwardly inclined position and the normally inclined position of the handle. The balancing axis is an axis that passes through the centers of cross-sectional surfaces of the handle at opposite ends of the finger seat. Pivoting of the balancing axis in the range from 10° to 40° insures obtaining an ergonomically optimal holding of the tool handle in both pivotal positions of the handle. The angle of 30° proved to be particularly advantageous as it insures an ergonomically favorable aligning of the handle in both pivotal positions.

Advantageously, an angle between the balancing axis in any one of the forwardly inclined positions of the handle and the normally inclined position of the handle and a perpendicular to the spindle axis amounts from 10° to 20°, preferably, to 15°. The inclination in the range from 10° to 20° provides an ergonomically optimal position of a to-be-held handle. An inclination of 15° provides for a handle-holding position of an operator hand on the handle that comes closest to the natural position of the hand-forearm position.

Advantageously, the handle can be secured with respect to the spindle axis, e.g., with appropriate locking means, in a plurality of positions. This permits to adapt the alignment of the handle, in comparison with conventional tools, to particular requirements and all possible applications.

Further, the actuator for switching the motor on and off extends advantageously along a longitudinal extent of the handle, passing through the center of the finger seat. The finger seat is defined as a bearing region for the small, ring, middle, and forefingers which is provided on the handle. As a rule, the finger seat is formed by a trough-shaped mold provided on a side of the handle facing in the operational direction of the tool. Thereby, in each contemplated holding position of the hand, it is insured that the actuator can be conveniently actuated by a finger lying on the finger seat.

It is particularly favorable when the actuator extends over a major portion of the finger seat, which insures that in each possible holding position of the holding hand, an adequate pressure is applied by fingers for actuating the actuator. According to a particular advantageous embodiment, the actuator is displaceable along the longitudinal extent of the handle, can be pushed therealong, whereby the position of the actuator can be adapted, in each position of the handle, in comparison with conventional tools, to a holding position of the holding hand.

Advantageously, the actuator has at least two fixed positions on the handle. Thereby, in both the forwardly inclined position and the normally inclined position, a particularly favorable position of the actuator can be predetermined by a corresponding arrangement of locking means. Then, the actuator is fixed in the predetermined position.

Advantageously, the actuator is provided at each of its opposite, in the displacement direction, ends, with a cover element for covering a guide formed in the handle. Such cover elements can be formed by aprons or tabs that project at the ends of the actuator away from the handle. The cover elements are formed of a flexible material or are pivotally supported on the actuator. The cover elements prevent penetration of dirt in the guide of the actuator, which can lead to malfunction.

Advantageously, the actuator can be formed as a tumbler switch that forms, at its two opposite ends, together with the handle respective pivot devices which operate in such a way that when one of two pivot devices is actuated, the other pivot device is simultaneously deactivated. Such a tumbler switch can be easily actuated by applying pressure to the pivot point remote from the actuated pivot point.

Alternatively, the actuator can be formed as a rocker switch. Thereby in each holding position of the holding hand on the handle, the actuator is easily actuated by applying pressure to one of its opposite ends.

The novel features of the present invention, which are considered as characteristics for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A power hand-held tool2, which is shown inFIG. 1, has a combined drilling and screw-driving function and includes essentially a motor unit4with a motor6shown with dash lines. A schematically shown gear unit10with a gear transmission8connects the motor6with a tool spindle12likewise shown with dash lines. At the front, facing in the operational direction A of the power tool2, end of the spindle12, there is provided a chuck14in which a working tool16is received. The tool spindle12has a spindle axis W.

At the rear, with respect to the operational direction A, end of the motor unit4, there is provided a handle18having a shape of a pistol grip, i.e., it is provided with an ergonomically favorable curvature. The handle18is held with a human hand H, with the small, ring, middle, and forefinger engaging or gripping a finger seat20. The finger seat20is provided on a side of the handle18facing in the operational direction A and is formed by a bottom of a trough-shaped mold. On the finger seat20, there is provided an actuator22which extends longitudinally in the central region of the seat20and is connected with the motor6.

The handle18pivots about a pivot axle D on which the motor unit4is held. A balancing axis G forms, in a normal position of the handle18shown inFIG. 1, a differential angle α of 15° with a perpendicular N to the spindle axis W. The balancing axis G extends through centers24a,24bof the transverse surfaces26a,26bat two opposite ends28a,28bof the finger seat20. In this way, the balancing axis for the handle18is inclined, starting from the spindle axis W and to the free end of the handle18, in a direction away from the operational direction A.

FIG. 2shows the hand-held tool2pivoted about the spindle axis W, with respect to the position shown inFIG. 1, by 180°, with the handle18being pivoted by an angle β of 30° in the operational direction A. To clearly show the pivot position of the handle18, angle β, the balancing axis of the normal position is designated with a reference character G1. In the position shown inFIG. 2, the handle18or its balancing axis β is inclined, with its free end, in the operational direction A. The differential angle α between the balancing axis β and the perpendicular N to the spindle axis W again amounts to 15° in the forwardly inclined position of the handle18.

Based on ergonomical consideration, the differential angle α of 15° was found to be most favorable. However, in accordance with individual preferences or for adaptation to the available space conditions, the differential angle α can vary from 10° to 20°. Moreover, together with a particularly favorable pivot angle β of 30° between the normally inclined and forwardly inclined position of the handle18, in accordance with individual preferences and outside conditions, the pivot angle β can vary between 10° and 40°.

With the forwardly inclined position of the handle18, it is possible to use the hand-held tool2for conducting work deep in angular region between the wall30and the bottom32, with conveniently holding the handle18with the hand H. In addition, due to the central arrangement of the actuator22, a convenient switching of the motor6on and off is possible.

FIG. 3shows a locking device34with a locking element36provided on the handle18and shown with dash lines. The locking element36is immovable in the plane of the drawing but is movable transverse to the plane of the drawings. The locking element36is engageable in a plurality of matching locking elements38provided in the motor unit4. By applying pressure to a lock switch40, which is provided on the handle18, a locking connection between the locking element36and a respective locking element38can be released, so that the handle18can be pivoted relative to the motor unit4into a new position in which the locking element36engages in a new matching locking element38. It is possible to provide a different, from three, number of locking position by providing a different number of matching locking elements38. It should be noted that different, from the locking device34, locking devices can be used for locking the handle18relative to the motor unit4.

The actuator22, which is shown inFIG. 3, is formed as a press-button displaceable in a longitudinal direction of the handle18at least in two positions. The upper position of the actuator22inFIG. 3is provided for the normally inclined position of the handle18, whereas the inner position, shown with dash-dot lines, is provided for the forwardly inclined position of the handle18. In both positions of the hand H on the handle18shown inFIGS. 1 and 2, depressing of the actuator22with the force and middle fingers can be conveniently effected.

In both positions, the actuator22lies on a tappet42of a switch4. When pressure is applied to the actuator22, it applies pressure to the tappet42displaceable in the switch enclosure46fixedly secured on the handle18. Dependent on how far the tappet42projects into the switch enclosure46, actuation of the motor6takes place.

As shown inFIG. 4, for a reliable locking of the actuator22, in both positions, on the handle18, there are provided two locking recesses48a,48bin which a locking nose50can engage. The locking nose50is also held on the handle18and is spring-biased with a biasing force F against a side wall52of the actuator22. Upon displacement of the actuator22along the displacement direction54relative to the locking nose50, the locking nose50engages in the locking recess48ain the first locking position of the actuator22shown with dot-dash lines or in the locking recess48bin the second locking position of the actuator22shown with solid lines. In addition to the locking recesses48a,48b, further recesses and, thus, further locking positions of the actuator22can be provided.FIG. 5shows another possibility of changing of locking positions of the actuator22on the handle18. For more clarity, only a portion of the handle18is shown. There is provided, on the actuator22, a plurality of engaging elements56spaced from a side wall52of the actuator22and engaging in respective predetermined locking positions in respective complementary engageable recesses58a,58bformed in the handle18. For releasing the actuator22from its locking position, the actuator22is pressed against a biasing force F1in a direction toward an inner side60of the handle18. The locking element56disengages from the respective recess58a, and the actuator22can be displaced until the locking element56reaches the other engageable recess58b. Upon release of pressure applied to the actuator22, it would be displaced by the biasing force F1away from the inner side60of the handle18, with the locking element56engaging in the next recess58b.

There are further provided cover elements62formed as rubber tabs displaceably arranged in elongated recesses64in the actuator22for covering a guide recess66. The cover elements62serve for covering, in each position of the actuator22, a section of the guide recess66which is not covered by the actuator66itself and through which different contaminants can penetrate into the interior of the handle, which can lead to malfunction. For the sake of clarity, inFIG. 5, only the cover element62at the lower end of the actuator22is shown. A corresponding cover element62, not shown, is also inserted in an elongated recess64at the upper end of the actuator22.

FIG. 6shows an embodiment in which the actuator22is formed as a tumbler switch. The actuator22extends, in this embodiment, almost over the entire length of the finger seat20and is provided at its opposite ends with a respective pivot device68. The pivot device68can be formed, e.g., by a bore70formed in the actuator22through which a pin72can extend which is fixedly secured on the handle18. Dependent on which tilting direction is required or desired, one or both of the pivot devices68can be actuated, with the corresponding pin72extending through the bore70. Simultaneously, the other three-point device is deactivated by withdrawing a pin72from the bore70.

With a pressure being applied to the actuator22, the actuator22tilts in the tilting direction74about the pin72of the actuated pivot device68and applies pressure to the tappet42of the switch44. There is provided in the center of the actuator22a guide element76that cooperates with a guide, not shown, formed in the handle18, providing for reliable axial guidance in both tilting directions74.

A further embodiment of an actuator22is shown inFIG. 7. In this embodiment likewise, the actuator22extends over the entire length of the finger seat20and can be actuated by application of pressure to its opposite ends. The actuator is supported on the handle18by an axle78. The tappet42of the switch44is so formed that upon application of pressure to any of opposite ends of the actuator22, it displaces in the switch enclosure46.