Electric machine tool and method for controlling the electric machine tool

1. A method for controlling an electric machine tool having an electric motor for driving a rotating insertion tool, comprising:

operating the electric machine tool in one of multiple predefined operating modes;

detecting an instantaneous operating mode of the electric machine tool;

detecting at least one parameter of the machine tool;

evaluating an instantaneous operating state of the electric machine tool based on the at least one detected parameter of the machine tool; and

activating a protective function when a presence of a critical operating situation is recognized during the evaluation of the instantaneous operating state;

wherein the evaluation of the instantaneous operating state of the electric machine tool is adapted in each case based on the detected instantaneous operating mode,

wherein an instantaneous rotational acceleration of the electric machine tool is detected as the at least one parameter of the electric machine tool, and

wherein, a first operating mode characterized by a low rotational speed of the rotating insertion tool has a first acceleration threshold value, and a second operating mode characterized by a high rotational speed of the rotating insertion tool has a second acceleration threshold value, wherein the first acceleration threshold value is higher than the second acceleration threshold value, wherein the protective function is activated if the instantaneous rotational acceleration exceeds the first acceleration threshold value in the first operating mode or exceeds the second acceleration threshold value in the second operating mode.

2. The method as recited in claim 1 , wherein at least one of (i) different evaluation methods and (ii) different evaluation circuits are used for evaluating the instantaneous operating state in different operating modes of the electric machine tool.

3. The method as recited in claim 1 , wherein a kickback event caused by jamming of the rotating insertion tool in the machine tool is recognized as a critical operating situation, and wherein the activation of the protective function causes one of (i) a reduction in power consumption of the electric motor or (ii) complete switching off of the electric motor.

4. The method as recited in claim 1 , wherein in a selected operating mode:

a rotational motion of the electric machine tool about a rotational axis of the insertion tool is monitored as the operating state;

a rotational rate of the electric machine tool is detected as the at least one parameter of the electric machine tool;

and

activation of the protective function during acceleration of the electric motor from a standstill to a predefined rotational speed is suppressed.

5. The method as recited in claim 1 , wherein the protective function is activated in an acceleration mode characterized by acceleration of the electric motor from a standstill to a predefined rotational speed when a deflection angle of the machine tool exceeds a predefined maximum deflection angle threshold value, and wherein the deflection angle of the machine tool is ascertained by mathematical integration over time of a rotational motion of the electric machine tool about a rotational axis of the insertion tool.

6. The method as recited in claim 1 , wherein a rotational acceleration of the electric machine tool about a rotational axis of the insertion tool is detected as the at least one parameter of the electric machine tool, and wherein the protective function is activated in an idle mode as soon as the detected rotational acceleration of the electric machine tool about a rotational axis of the insertion tool exceeds a predefined first acceleration threshold value for a predefined first minimum time period.

7. The method as recited in claim 6 , wherein in a load mode, which follows the idle mode and which is characterized by gradual deceleration of the electric motor from idle speed, the protective function is activated as soon as at least one of (i) the detected rotational acceleration of the electric machine tool about the rotational axis of the insertion tool exceeds a predefined second acceleration threshold value which is less than the predefined first acceleration threshold value, for a predefined second minimum time period which is longer than the predefined first minimum time period, and (ii) a deflection angle of the electric machine tool ascertained by mathematical integration exceeds a predefined deflection angle threshold value.

8. The method as recited in claim 6 , wherein the protective function is deactivated in a chiseling mode in which the insertion tool undergoes a translational motion.