HAND-HELD POWER TOOL, TOOL AND HAND-HELD POWER TOOL SYSTEM WITH A DETERMINED SPEED/IMPACT POWER RATIO

Abstract

A hammer drill having an impact mechanism and a rotary drive, wherein the hammer drill is designed to rotate a tool at a speed n about a longitudinal axis of the tool and to drive it with an output impact power PS along the longitudinal axis with a striking movement is disclosed. At a working point, at least one condition is met: 1. The ratio of the output impact power PS to the speed n is at least 3.5 W/rpm; 2. Depending on the output impact power PS, the speed n is at most (PSAN−300)2/2000+150) rpm; 3. In the event of an infinitesimal change in the output impact power PS, the speed n changes by at most 0.1 rpm/W.

Claims

5. The hand-held power tool as claimed in claim 1, wherein the hand-held power tool has a multi-stage transmission.

6. The hand-held power tool as claimed in claim 1, wherein the hand-held power tool has a tool recognition device for identifying a type of tool used in a tool fitting of the hand-held power tool, and/or in that the hand-held power tool is configured such that the type of tool used in the tool fitting can be set by a user of the hand-held power tool.

7. The hand-held power tool as claimed in claim 1, having a pneumatic cuttings conveying device.

8. The hand-held power tool as claimed in claim 1, wherein the hand-held power tool can be operated wirelessly.

9. The hand-held power tool as claimed in claim 1 comprising at least one overrunning clutch, a gate-type transmission or a circular thrust transmission.

10. A tool for a hand-held power tool as claimed in claim 1, comprising a tool tip, a tool shaft and a shank for holding the tool in a tool fitting of the hand-held power tool, wherein a material transport channel is formed at least along the tool shaft, wherein the material transport channel has a minimum cross-sectional area of 19 mm.sup.2 or at least 6% of a cross-sectional area of a borehole which can be produced by the tool.

11. The tool as claimed claim 10, wherein the tool is in the form of a suction drill.

12. A hand-held power tool system, comprising a hand-held power tool comprising an impact mechanism and a rotary drive, wherein the hand-held power tool is configured to rotate a tool at a rotational speed n about a longitudinal axis of the tool and to drive the hand-held power tool with an impact movement along the longitudinal axis with an output impact power PS, and wherein the hand-held power tool is portable, wherein at least one of the following conditions is met at a working point of the hand-held power tool: 1. a ratio of the output impact power PS to the rotational speed n is at least 3.5 W/rpm; 2. the rotational speed n is at most ((PS/W−300){circumflex over ( )}2/2000+150) rpm depending on the output impact power PS; 3. in an event of an infinitesimal change in the output impact power PS, the rotational speed n changes by at most 0.1 rpm/W, and a tool comprising a tool tip, a tool shaft and a shank for holding the tool in a tool fitting of the hand-held power tool, wherein a material transport channel is formed at least along the tool shaft, wherein the material transport channel has a minimum cross-sectional area of 19 mm.sup.2 or at least 6% of a cross-sectional area of a borehole which can be produced by the tool.

13. The hand-held power tool of claim 2, wherein the at least one drive unit is a motor.

14. The hand-held power tool of claim 3, wherein the output impact power PS is between 200 W and 1000 W, at least at the working point.

15. The hand-held power tool of claim 4, wherein the impact mechanism is an electropneumatic impact mechanism.

16. The hand-held power tool of claim 7, having an electropneumatic cuttings conveying device.

17. The hand-held power tool of claim 8, having a battery.

18. The hand-held power tool of claim 17, having a lithium-containing battery.

19. The tool of claim 10, wherein the material transport channel has a minimum cross-section area of at least 12% of the cross-section area of the borehole which can be produced by the tool.

20. The hand-held power tool as claimed in claim 2, wherein the output impact power PS is between 200 W and 2000 W at least at the working point.

Description

[0055] In the schematic drawing, exemplary embodiments of the invention are shown and explained in more detail in the following description.

[0056] The only FIGURE (FIG. 1) shows a hand-held power tool system.

[0057] A hand-held power tool system 10 has a hand-held power tool 12. The hand-held power tool 12 can be operated wirelessly. For this purpose, it has a rechargeable battery 14. It is in the form of a portable device. It preferably has a weight of between 5 and 15 kg and generally of less than 25 kg.

[0058] It also has a tool fitting 16.

[0059] A tool 18 is held in the tool fitting. For this purpose, the tool 18 has a tool shaft 20, at one end of which a shank 22 is formed and at the other end of which a tool tip 24 is formed.

[0060] The tool 18 is in the form of a hollow drill and in particular a suction drill. For this purpose, it has a material transport channel 26, which runs inside the tool shaft 20 and is shown schematically in FIG. 1, via which cuttings extracted from the vicinity of the tool tip 24 can be conveyed to a cuttings conveying device 28.

[0061] The material transport channel 26 has a cross-sectional area of 15% of the cross section of a borehole to be created by the tool 18.

[0062] Furthermore, the hand-held power tool 12 has an operating mode selector switch 30 for switching between different operating modes, in particular for switching between a pure drilling mode, a pure chiseling mode and a hammer drill mode. In the position shown of the operating mode selector switch 30, the hammer drill mode is selected.

[0063] The hand-held power tool 12 also has an electropneumatic impact mechanism 32 and a rotary drive 34. The impact mechanism 32 and the rotary drive 34 are driven by a common drive unit 36, an electric motor. The hand-held power tool 12 is configured to rotate the tool 18 held in the tool fitting 16 at a rotational speed n about a longitudinal axis L of the tool 18 and to drive said tool along the longitudinal axis L with an impact movement such that an impact power PS is output.

[0064] The hand-held power tool 12 has at least one transmission. The transmission can, for example, have an overrunning clutch, a gate-type transmission or a circular thrust transmission in accordance with the European patent applications mentioned at the beginning and incorporated by reference.

[0065] The hand-held power tool 12 can be set in motion by means of an actuating lever 31 and, in particular, operated at a working point with a device-related highest possible output impact power PS.

[0066] In this exemplary embodiment, the ratio of the output impact power PS to the rotational speed n at the working point is 4 W/rpm, in particular with an output impact power PS of 0.5 kW and a rotational speed n of 125 rpm.

[0067] Further exemplary embodiments which, unless expressly stated otherwise, correspond to this preceding exemplary embodiment are described below.

[0068] In the case of an exemplary embodiment of the hand-held power tool 12 that is especially tailored to the use of a tool 18 in the form of a hollow drill, the output impact power PS is also 0.5 kW at a rotational speed of 5*10.sup.1 rpm.

[0069] This hand-held power tool 12 is configured to generate a single impact energy of 10.sup.1 joules at an impact frequency f of 5*10.sup.1 Hz at the working point. This hand-held power tool 12 has a tool recognition device or, according to a particular embodiment, alternatively a tool selector switch with which a user of the hand-held power tool 12 can set a type of tool. The hand-held power tool 12 is then configured, when a hollow drill is recognized or set as the type of tool, to lower the rotational speed to a maximum of 5*10.sup.1 rpm, for example, and to increase same in the case of other types of tools, for example rock drills with a helical structure. For this purpose, in contrast to the previous exemplary embodiment, the hand-held power tool 12 has two drive units 36 for separately driving the impact mechanism 32 and the rotary drive 32. As a result, the hand-held power tool 12 is also capable of keeping the rotational speed n of 5*10.sup.1 rpm, which is mentioned by way of example in the case of a hollow drill as the tool 18, constant,—or of keeping another low rotational speed n, corresponding to at least one of the three conditions, constant, independently of the output impact power PS.

[0070] In a further, modified embodiment, preferably again with only one common drive unit 36, the hand-held power tool 12 has a multi-stage transmission. The hand-held power tool 12 is configured to switch the transmission depending on the recognized or set type of tool. In particular, in the case of a hollow drill, a particularly greatly reduced shifting step of the transmission is engaged.

[0071] This transmission too can, for example, have an overrunning clutch, a gate-type transmission or a circular thrust transmission in accordance with the European patent applications mentioned at the beginning and incorporated by reference.

[0072] The hand-held power tools 12 according to these aforementioned exemplary embodiments are thus configured to meet the 1st condition, by means of which a rotational speed n of at most approx. 170 rpm can be achieved at the working point with 0.5 kW.

[0073] They are also configured to meet the 2nd condition, by means of which a rotational speed n of at most approx. 143 rpm can be achieved at the working point with 0.5 kW.

[0074] In a further exemplary embodiment of a hand-held power tool 12, the output impact power PS at the working point is 0.45 kW at a rotational speed n of approximately 7*10.sup.1 rpm. The gradient at the working point, i.e. with an output impact power of 0.45 kW, is 0.05 rpm/W, i.e. with an infinitesimal changes in the output impact power PS, the rotational speed n changes by 0.05 rpm/W. This hand-held power tool 12 thus simultaneously corresponds to conditions 1, 2 and 3. It also has a particularly high level of efficiency in partial load operation, i.e. at output impact powers PS of below 0.45 kW.