HAND-HELD POWER TOOL

Abstract

The invention relates to a hand-held power tool having a drive motor and a striking mechanism for the rotating or impact drive of a tool, which is accommodated in a tool holder. A transmission gearing and a torque clutch are disposed in the transmission path between the drive motor and the tool holder in order to limit the transferable torque. A threshold torque can be set in the torque clutch.

Description

The invention relates to a hand-held power tool that can be used as a rotary hammer and as a drill and is equipped with a drive motor and an impact mechanism for driving a tool in a rotating and hammering mode and/or in an impact mode.

PRIOR ART

DE 10 2005 047 600 A1 describes a hand-held power tool embodied in the form of a rotary hammer that can be used in various operating modes. On the one hand, it can be operated as a rotary hammer in which the drive motion of the drive motor can be transmitted to the drill chuck holding the tool via a rotary drive mechanism that can be switched on and off and via an impact mechanism. If only the impact mechanism is active, but not the rotary drive mechanism, then the rotary hammer is in chisel mode. But if both the rotary drive mechanism and impact mechanism are activated, then the rotary hammer is operated in impact drill mode. In another switch configuration, the impact mechanism is deactivated and only the rotary drive mechanism is active so that the rotary hammer is operated in drill mode.

There are also known hand-held power tools that are equipped with a torque-limiting unit that assumes the function of an overload clutch in order to interrupt the flow of force between the motor output and the driving element of the tool if the transmitted torque exceeds an overload torque. A hand-held power tool of this kind that is embodied in the form of a cordless screwdriver is described for example in DE 10 2004 058 809 A1. The torque-limiting unit can be used to drive screws with a uniform torque.

DISCLOSURE OF THE INVENTION

Based on this prior art, the object of the invention is to provide a hand-held power tool that is equipped as a rotary hammer with an additional operating functionality.

This object is attained according to the invention by means of the defining characteristics of claim 1. Suitable modifications are disclosed in the dependent claims.

The hand-held power tool according to the invention can be used both as a rotary hammer and as a drill and is equipped with a drive motor and an impact mechanism. The rotary drive mechanism and the impact mechanism can advantageously be switched on and off to enable implementation of various functions. For example, when the rotary drive mechanism is deactivated and only the impact mechanism is active, it is possible to operate in a chisel mode. The rotary hammer function is achieved by additionally activating the rotary drive mechanism When the impact mechanism is switched off, the hand-held power tool is in drill-only mode.

In the hand-held power tool according to the invention, a reduction gear and a torque clutch for limiting the transmissible torque are situated in the transmission path between the drive motor and the tool holder in which the tool is accommodated. Ideally, the torque clutch should be switchable between an operative position and an inoperative position in which the torque limitation is deactivated. It is either possible to mechanically bypass the reduction gear so that the reduction gear can also be switched between an inoperative position and an operative position and/or it is possible to set different transmission ratios in the reduction gear. In the operative position or with a correspondingly set transmission ratio, the reduction gear permits the hand-held power tool to be operated as a rotary hammer with a reduced speed in comparison to the drill-only mode. The torque clutch assures that the transmitted torque does not exceed a threshold torque in screwdriving mode. This threshold torque is preferably adjustable; it is possible, for example, for at least two, but possibly more, torque stages to be provided or for there to be an infinitely variable adjustment of the threshold torque.

In addition to the rotary hammer mode, drill mode, and chisel mode, it is thus also possible for there to be a screwdriving mode in which the reduction gear reduces the high-speed drive motion of the drive motor to a lower-speed rotary motion suitable for the screwdriving functionality; simultaneously, through activation of the torque clutch, it is possible to set a maximum permissible torque. The activation of the torque clutch is optional; if need be, it can also be omitted in the screwdriver mode or drill mode so that there is no torque limitation.

According to a preferred embodiment, the drive motor, the reduction gear, the impact mechanism, and the torque clutch are situated one after another and flush with one another in a line, thus assuring an advantageous transmission of force from the drive motor via the intermediate units to the tool holder with the tool contained therein.

According to a first preferred embodiment, the torque clutch is situated between the impact mechanism and the tool holder. According to a second preferred embodiment, it is also possible to position the torque clutch before the impact mechanism and the tool holder. In both cases, the reduction gear is suitably situated immediately at the output side of the drive motor and before the impact mechanism and torque clutch.

In a preferred embodiment, the reduction gear is embodied in the form of a planetary gear that advantageously has at least two switchable reduction ratios. Either all of the planetary stages of the planetary gear are operational to permit a sharply reduced transmission of the rotary drive motion of the drive motor to the tool for the screwdriving mode or one gear of the planetary gear increases the drive motion of the drive motor to a speed that enables a drill mode.

In another advantageous embodiment, the hand-held power tool is equipped with a battery pack to supply current to the drive motor, which is embodied as electrical. The battery pack is in particular detachably mounted to the housing of the hand-held power tool and can be recharged as needed in a charging unit.

The impact mechanism by means of which the rotary hammer mode and chisel mode are to be adjusted is either pneumatically or mechanically embodied and actuated. In either case, the activation of the impact mechanism is optional.

Other advantages and suitable embodiments can be inferred from the remaining claims, from the description of the figures, and from the drawings themselves.

DRAWINGS

FIG. 1 shows a hand-held power tool embodied in the form of a rotary hammer that is equipped with a drive motor and an impact mechanism for driving a tool in a rotating and hammering mode and is also equipped with a reduction gear and a torque clutch for limiting the transmissible torque so that the hand-held power tool can be used as a rotary hammer, a drill, a chisel, and a screwdriver,

FIG. 2 shows a modified embodiment of the hand-held power tool.

In the drawings, components that are the same have been provided with the same reference numerals.

The hand-held power tool shown in FIG. 1 is a rotary hammer that has a housing 2 containing an electric drive motor 3 that is provided with current by means of a battery pack 4 at the bottom of the housing. The battery pack 4 is detachably mounted to the housing. The electric drive motor is actuated by means of a manual switch 5.

To improve the maneuvering of the hand-held power tool 1, a second handle can be provided on the housing 2.

The housing 2 of the hand-held power tool 1 also contains a planetary gear 6, an impact mechanism 7, and a torque clutch 8. The planetary gear 6 is situated immediately at the output side of the electric drive motor 3. It is adjoined by the impact mechanism 7 with which the hammering or impact function is implemented. Adjacent to the impact mechanism 7 is the torque clutch 8. The torque clutch 8 is connected to the tool holder 9 for accommodating a tool 10; for example, the tool holder 9 is embodied in the form of a drill chuck or slit clamping sleeve.

The electric drive motor 3, the planetary gear 6 functioning as a reduction gear, the impact mechanism 7, and the rotary clutch are arranged one after another in the housing 2 of the hand-held power tool 1 and share a common longitudinal axis that is simultaneously the rotation axis of the drive motor and of the tool holder 9 with the tool 10. The planetary gear 6 is advantageously provided with different gear stages that can be set by the user. The impact mechanism 7 is embodied so that it can be switched on and off, as is the torque clutch 8, which preferably can be used to set different-level torque thresholds that can be transmitted between the electric drive motor and the tool holder.

The exemplary embodiment of a hand-held power tool 1 shown in FIG. 2 is largely identical to the one shown in FIG. 1 and for this reason, the reader can refer to the description relating to FIG. 1. What differs, however, is the arrangement of the impact mechanism 7 and torque clutch 8. The torque clutch 8 directly adjoins the planetary gear 6, which is situated at the output side of the electric drive motor 3. The torque clutch 8 is adjoined by the impact mechanism 7 to which the tool holder 9 is coupled.

In an alternative embodiment not shown here, the torque clutch 8 encompasses the impact mechanism 7.

Claims

1-13. (canceled)

14. A hand-held power tool that is usable as a rotary hammer and as a drill, comprising:

a drive motor:

an impact mechanism for driving a tool of the hand-held power tool in a rotating and/or hammering mode;

a tool holder accommodating the tool; and

a reduction gear and a torque clutch which limit the transmissible torque being situated in a transmission path between the drive motor and tool holder, wherein a torque limitation in the torque clutch can be set.

15. The hand-held power tool as recited in claim 14, wherein the drive motor, the reduction gear, the impact mechanism, and the torque clutch are situated one after another and flush with one another in a line.

16. The hand-held power tool as recited in claim 14, wherein the torque clutch is situated between the impact mechanism and the tool holder.

17. The hand-held power tool as recited in claim 15, wherein the torque clutch is situated between the impact mechanism and the tool holder.

18. The hand-held power tool as recited in claim 14, wherein the impact mechanism is situated between the torque clutch and the tool holder.

17. The hand-held power tool as recited in claim 15, wherein the impact mechanism is situated between the torque clutch and the tool holder.

20. The hand-held power tool as recited in claim 16, wherein the reduction gear is situated immediately at the output side of the drive motor.

21. The hand-held power tool as recited in claim 18, wherein the reduction gear is situated immediately at the output side of the drive motor.

22. The hand-held power tool as recited in claim 20, wherein the reduction gear is a planetary gear.

23. The hand-held power tool as recited in claim 21, wherein the reduction gear is a planetary gear.

24. The hand-held power tool as recited in claim 14, wherein the hand-held power tool is equipped with a battery pack which supplies current to the electric drive motor.

25. The hand-held power tool as recited in claim 15, wherein the hand-held power tool is equipped with a battery pack which supplies current to the electric drive motor.

26. The hand-held power tool as recited in claim 14, wherein the impact mechanism is mechanically actuated.

27. The hand-held power tool as recited in claim 15, wherein the impact mechanism is mechanically actuated.

28. The hand-held power tool as recited in claim 14, wherein the impact mechanism is pneumatically actuated.

29. The hand-held power tool as recited in claim 15, wherein the impact mechanism is pneumatically actuated.

30. The hand-held power tool as recited in claim 14, wherein it is possible to set at least two torque stages in the torque clutch when it is in an operative position.

31. The hand-held power tool as recited in claim 14, wherein the tool holder is embodied in the form of a drill chuck.

32. The hand-held power tool as recited in claim 14, wherein the tool holder is embodied in the form of a slit clamping sleeve.

33. The hand-held power tool as recited in claim 14, wherein it is possible to switch the torque clutch between an operative position and an inoperative position in which the torque limitation is deactivated in the inoperative position.