Handheld power tool, method for operating a handheld power tool

A handheld power tool, in particular an electric handheld power tool, includes an actuable drive device configured to drive a tool and an illumination device. The illumination device is connected to an acceleration sensor and varies its generated light depending on movements of the handheld power tool that are detected by the acceleration sensor.

This application claims priority under 35 U.S.C. §119 to patent application no. DE 10 2014 206 271.3, filed on Apr. 2, 2014 in Germany, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The disclosure relates to a handheld power tool, in particular an electric handheld power tool, comprising an actuable drive device for driving a tool, and comprising an illumination device.

Furthermore, the disclosure relates to a method for operating such a handheld power tool comprising an actuable drive device for driving a tool and an illumination device.

Handheld power tools and methods for operating them are known from the prior art. In this regard, electrically operated handheld screwdrivers are known, for example, at the tip of which a light-emitting diode is provided, which illuminates the tool tip or the workpiece in the region of the tool tip. This is intended to make it easier for the user to correctly position the screw and screw it in. Corresponding apparatuses are also known in the case of drills, for example.

SUMMARY

The handheld power tool according to the disclosure has the advantage that the light generated by the illumination device offers the user more than just illuminating the workpiece. It facilitates orientation and additionally conveys information to the user. The user, who will always observe the workpiece, in particular that location of the workpiece which is to be processed, intuitively takes in the information provided by the illumination device, as a result of which the work with the handheld power tool is simplified and optimized. According to the disclosure, for this purpose it is provided that the illumination device is connected to an acceleration sensor and varies the generated light depending on acceleration values or movements of the handheld power tool which are detected by the acceleration sensor. As a result of the detection of accelerations of the handheld power tool, movements of the handheld power tool are detected in a simple manner. In particular, it is provided that the generated light upon movements being detected differs from the generated light which is emitted if no movements are detected. This signals to the user in a simple manner that the handheld power tool is being held steadily enough to carry out an optimum processing operation. If the user moves the handheld power tool back and forth too much, it is possible, for example by a warning color being set, to make the user aware that at present a processing operation should not yet be carried out by the user.

In accordance with one advantageous development of the disclosure, it is provided that the illumination device comprises means for varying a light cone of the illumination device. The illumination device generates a light cone which is expediently directed onto the workpiece to be processed or onto the tool tip. As a result of the light cone being varied, information for optimizing the processing can be conveyed to the user.

In particular it is provided that the illumination device comprises means for directing the light cone. In this case, for example, depending on an orientation of the handheld power tool, which can be detected for example by means of an electric spirit level or the like, the light cone can provide information if the light cone is directed away from the tip of the tool, in order to symbolize a quasi-eccentric orientation of the tool tip with respect to the light cone.

In accordance with one preferred development of the disclosure, it is provided that the illumination device comprises means for expanding or narrowing the light cone. As a result of the light cone being expanded or narrowed, the generated light can be generated in a concentrated fashion or diffusely. In this regard, it is provided, in particular, that if no or only small accelerations are detected by the acceleration sensor, the light cone is narrowed in order to focus the location to be processed. If the handheld power tool is moved to a great extent, then the light cone is expanded in order to generate a diffuse light distribution, as a result of which the user intuitively grasps that the tool is not yet in optimum processing steadiness.

Preferably, it is provided that the means comprise a light-emitting diode array whose light-emitting diodes are actuable independently of one another with regard to their brightness, in order that the light cone generated overall is directed, narrowed or expanded by means of the actuation of the light-emitting diode array. More light-emitting diodes are activated for expansion, for example, which light-emitting diodes are deactivated again for narrowing. For directing the light cone, it is possible to activate different light-emitting diodes, which are oriented in particular in different directions.

Preferably, it is furthermore provided that the light-emitting diode array is embodied in a manner surrounding the tool in particular coaxially. What is achieved by the light-emitting diodes of the light-emitting diode array being arranged in a manner surrounding the tool is that the workpiece is covered uniformly by the light cone, without the tool itself casting a shadow on the workpiece. Furthermore, what is achieved by the in particular coaxial arrangement of the light-emitting diodes of the light-emitting diode array is that expansion or narrowing of the light cone can be related directly to the tool.

In accordance with one advantageous development of the disclosure, it is provided that the means comprise at least one in particular displaceable lens whose transparency is variable for influencing the light cone. In particular, by varying the transparency, it is possible to influence the intensity of the light cone or of the generated light. In this regard, it is provided, for example, that with decreasing movements of the handheld power tool, the light intensity is intensified, in particular by the transparency of the lens being increased. Correspondingly, upon greater movements being detected, the transparency of the lens is reduced in order to reduce the light intensity.

In accordance with one advantageous development of the disclosure, it is additionally provided that the means comprise at least one reflector that is displaceable for influencing the light cone. Preferably, the reflector is rotatably or pivotably mounted in order to direct the generated light cone. It is also conceivable to make the reflector translationally displaceable, in order to expand or narrow a light cone. In this case, it is provided, in particular, that the reflector and the abovementioned lens together generate the light cone of the illumination device.

The method according to the disclosure leads to the advantages already mentioned above. It is distinguished by the fact that the handheld power tool is monitored for movements by means of an acceleration sensor, and that the light generated by the illumination device is varied depending on the detected movements of the.

In particular, it is provided that a light cone of the acceleration device is varied depending on the detected movements. Preferably, the light cone is expanded if no or only small accelerations are detected. In particular, the light cone is narrowed in such a way that the generated light is focused onto the tool tip or onto the workpiece situated in front of the tool tip. Further advantages and features are evident from the description already given above and from the claims.

DETAILED DESCRIPTION

FIG. 1shows a handheld power tool1in a simplified side view, said handheld power tool being embodied as an electric drill. In this regard, the handheld power tool1comprises a pistol-shaped housing2, in which is arranged a drive device3for driving a tool4, which is embodied as a drill bit in the present case. The drive device3is embodied as an electric motor which is supplied with electrical energy from an exchangeable energy store5.

An actuation switch6is additionally provided on the housing2, said switch being adjustable in a continuously variable manner, such that a user can predefine the rotational speed and/or the torque of the drive device3for driving the drill bit4by actuating the actuation switch6. In this case, the actuation position of the actuation switch6is detected by a control unit7and converted into the corresponding signals for driving the drive device3. The control unit7is arranged on a printed circuit board8, on which an acceleration sensor9and an illumination device10are additionally arranged. In this case, the illumination device10is arranged at the foot of a handle section of the pistol-shaped housing2near the energy store5.

The control unit7monitors the measurement values detected by the acceleration sensor9and actuates the illumination device10depending on detected movements or accelerations of the handheld power tool1.

In this case, it is provided that if the acceleration sensor9detects movements of the handheld power tool1, the control unit7actuates the illumination device10in such a way that the illumination device10sets an expanded light cone, as shown by dotted boundary lines11, such that a workpiece12to be processed is illuminated over a large area. If the measurement values of the acceleration sensor9fall below a predefinable lower limit value, then the control unit7actuates the illumination device10in such a way that the light cone is narrowed, as indicated by dashed boundary lines13. In this case, the light cone of the illumination device10is focused onto the processing location of the workpiece12or onto the tip of the tool4.

This has the effect that if the user moves the handheld power tool1, the workpiece12is illuminated over a large area, and that as soon as the user holds the handheld power tool1more steadily, for example shortly before carrying out a drilling operation, the light cone of the illumination device10is focused onto the processing location or the tool tip4. As a result, the user intuitively perceives whether said user is holding the handheld power tool1steadily enough for carrying out a drilling operation.

FIG. 2shows a first exemplary embodiment of the illumination device10in a simplified detail illustration. The illumination device10comprises at least one light source, which is embodied as a light-emitting diode14in the present case. The light emitted by the light-emitting diode14impinges on a lens15, which is arranged in a manner displaceable translationally relative to the luminous source, as indicated by a double-headed arrow. The lens15is optionally also mounted pivotably about an axis, in particular about its axis of symmetry, as indicated by a curved double-headed arrow. By displacing and rotating the lens15, it is possible to influence and in particular direct the light generated by the light source or by the light-emitting diode14. In this case, the light cone leaving the lens15can for example be directed by the pivoting of the lens15and be expanded or narrowed by the movement of the lens. Preferably, the transparency of the lens15is additionally variable in order to influence the luminous intensity of the light cone depending on the detected movements.

FIG. 3shows an alternative exemplary embodiment of the illumination device10, in which the exemplary embodiment known fromFIG. 2was supplemented by a reflector16. The reflector16is likewise displaceable translationally with respect to the light-emitting diode14and optionally pivotable about an axis, as indicated by double-headed arrows. In this case, the orientation of the light-emitting diode14was changed by 180°, such that it irradiates the reflector16, which concentrates the emitted light and directs it onto the lens15behind the light-emitting diode14.

FIG. 4shows a further exemplary embodiment of the handheld power tool1, which exhibits one advantageous configuration of the illumination device10. In contrast to the previous exemplary embodiments, the illumination device10in this case is formed by a light-emitting diode array17formed by a multiplicity of light-emitting diodes18, only some of which are provided with reference signs in the present case. The light-emitting diodes18are actuable independently of one another and adjustable in particular in terms of their light intensity. In the present case, the light-emitting diode array17is arranged coaxially with respect to the tool4of the handheld power tool1, wherein the light-emitting diode array17for this purpose extends in a ring-shaped fashion over the front side of the handheld power tool1. In this case, the light-emitting diodes18are preferably arranged in a ring-shaped fashion in rows, wherein some of the light-emitting diodes18are preferably arranged in a manner facing in different directions. The control unit7actuates the light-emitting diodes18individually depending on the measurement values of the acceleration sensor9in order to expand or narrow the light cone generated by the illumination device10or by the light-emitting diode array17, depending on whether the handheld power tool1is being moved or held steady. In particular, it is provided that a first group of light-emitting diodes of the light-emitting diode array17is actuated, which light-emitting diodes form a narrowed light cone13, if the handheld power tool1is held steady, and additionally a second group of light-emitting diodes18is switched on or activated if movements of the handheld power tool1are detected, which in particular exceed a predefinable limit value.

The movements of the handheld power tool1are thus detected continuously during operation. As soon as the detected accelerations or measurement values of the acceleration sensor9exceed the predefinable limit value, the illumination device10is actuated in such a way that the light cone is expanded. If the measurement values fall below the lower limit value, then the light cone is narrowed in order to be concentrated or focused onto the processing location. As a result of the advantageous coaxial formation of the light-emitting diode array17in accordance with the exemplary embodiment inFIG. 4, what is furthermore achieved is that the tool4itself does not cast a shadow on the workpiece, which simplifies processing.

In accordance with a first variant, the light-emitting diodes17are individually activated or deactivated depending on the measurement values of the acceleration sensor9in order to expand or narrow the light cone of the illumination device10. Alternatively, however, it is also conceivable to vary the light intensity of the light-emitting diodes in a stepwise manner, such that for example the narrowed light cone has a higher light intensity than the expanded light cone. In this regard, it can be provided that if the measurement values fall below the limit value, the light-emitting diodes18which serve for the large-area lighting or illuminating of the workpiece12by means of the expanded light cone are reduced in terms of their light intensity, such that the expanded light cone remains in principle, but appears with lower luminosity.

The light-emitting diodes18are expediently arranged in such a way that together they can generate a sufficiently large light cone with at least substantially uniform lighting.