Method and device for detecting a impact event of a rotary impact tool

Abstract

The present invention relates to a method and a device for detecting an impact event of a rotary impact tool comprising a, preferably rotatable, tool shaft (10) which is connected at its free end to a tool, and an impact mechanism configured to exert a rotary and / or axial impact on the tool shaft (10).The method comprises steps for measuring a rotational position and / or rotational speed of a motor output (2, 4) of an electric motor (1) that drives the tool shaft (10) via a percussion mechanism; calculating an acceleration of the motor output (2, 4) of the electric motor (1) based on the rotational position and / or rotational speed of the motor output (2, 4) of the electric motor (1); determining zero crossings of the acceleration of the motor output (2, 4) of the electric motor (1) or determining zero crossings of the derivative of the acceleration (a) of the motor output (2, 4) of the electric motor; and detecting the impact event at a previously determined zero crossing.

Description

[0001] The invention relates to a method and a device for detecting an impact event of a rotary impact tool.

[0002] Impact wrenches are known, for example, from EP 3 501 740 A1, EP 3 501 741 A1, EP 3 439 830 B1 and DE 10 2019 215 417 A1.

[0003] Previous impact detection systems used signals and sensors such as those listed below. A common method was to use a current sensor, which categorized the current state of the impact wrench based on the current profile of a motor or battery. The current profile exhibits characteristic features during impact operation, including an increased constant component and a component that pulsates with the impact frequency. In addition, inertial sensors, accelerometers, gyroscopes, and IMUs (Inertial Measurement Units) were used. These systems measured the acceleration and velocity of an impact wrench, for example, in both translational and rotational directions, which also exhibit a pulsating component at the impact frequency during impact operation.In addition, vibration sensors were used, whereby each impact generated a vibration within the mechanism (structure-borne sound) as well as the surrounding material (air), which was then measured. Position sensors were also used, whereby an impact event was inferred by measuring the axial position of a hammer or the rotational position of an anvil.

[0004] A disadvantage of such systems is the high cost; in particular, the use of this additional sensor technology results in considerable material and production costs. Battery-powered hand tools, in particular, are very cost-sensitive.

[0005] Furthermore, detection reliability was often unsatisfactory. If detection is to be performed by measuring the current waveform, the signal-to-noise ratio is very unfavorable depending on the operating point, leading to frequent detection errors. The current measurement example illustrates that the motor's current signal, in addition to the dynamics of the impact mechanism, also contains components resulting from the commutation of a brushless DC motor, the general control of the power electronics, and the current battery state. Inertial signals serve as another example. These include, besides the direct excitation by the impact event, externally induced vibrations and accelerations, as well as all natural frequencies of the entire system consisting of the machine, tool, consumables, and user. The amplitude of the respective signal components is highly dependent on the application.

[0006] The space required can also pose a problem. Each additional sensor requires a considerable amount of installation space. This contradicts the goal of a lightweight and compact machine. A negative example is an anvil position sensor, which significantly lengthens the machine in the direction of the motor output shaft.

[0007] Furthermore, disadvantages can arise in terms of production and usage complexity. Additional components, such as sensors, cables, connectors, or switches, increase production complexity and thus also the susceptibility to errors in the production process. If the function is provided via an add-on module, this can represent additional complexity for the user.

[0008] The object of the present invention is to detect an impact event in a rotary impact tool in a cost-effective and safe manner.

[0009] This problem is solved by the articles with the features according to the independent claims. Further embodiments are shown in the dependent claims.

[0010] According to a first aspect of the invention, a method for detecting an impact event of a rotary impact tool comprises a, preferably rotatable, tool shaft connected at its free end to a tool, and an impact mechanism configured to exert a rotary and / or axial impact on the tool shaft, the method comprising: measuring a rotational position and / or rotational speed of a motor output of an electric motor driving the tool shaft via the impact mechanism; calculating an acceleration of the motor output of the electric motor based on the rotational position and / or rotational speed of the motor output of the electric motor; determining zero crossings of the acceleration of the motor output of the electric motor or determining zero crossings of the derivative of the acceleration of the motor output of the electric motor; and detecting the impact event at a zero crossing determined above.

[0011] According to a second aspect of the invention, a device for detecting an impact event of a rotary impact tool is provided. The rotary impact tool has a tool shaft, preferably rotatable, which can be connected to a tool at its free end, and an impact mechanism configured to exert a rotary and / or axial impact on the tool shaft.The device comprises the following: a measuring device configured to measure the rotational position and / or rotational speed of a motor output of an electric motor that drives the tool shaft via the impact mechanism; a calculating device configured to calculate the acceleration of the motor output of the electric motor based on the rotational position and / or rotational speed of the motor output of the electric motor; a determining device configured to determine zero crossings of the acceleration of the motor output of the electric motor or zero crossings of the derivative of the acceleration of the motor output of the electric motor; and a detection device configured to detect the impact event at a zero crossing determined above.

[0012] According to a third aspect of the invention, a percussion rotary tool has a device for detecting a percussion event.

[0013] Within the scope of the present application, a zero crossing of the acceleration of the motor output can be a transition from a positive acceleration to a negative acceleration.

[0014] In the present invention, it is assumed that the impact event occurs or has occurred after either the acceleration of the motor output element has reached a local maximum, i.e., when the derivative of the acceleration has passed through a zero crossing, or when the acceleration itself has passed through a zero crossing.

[0015] The developed method can detect an impact event in the impact rotary tool cost-effectively and safely, as it uses existing sensors, such as the Hall sensors commonly found in electric motors, which can be used to measure the rotational position and / or rotational speed of the motor output of an electric motor.

[0016] Advantageously, the present invention can be suitablely applied to all types and sizes of impact wrenches. The method can be implemented on existing hardware. This makes the method very cost-effective, requires no additional installation space, and leaves production complexity unaffected. Since the method is implemented directly on the machine, it does not present any increased complexity for the user.

[0017] Further exemplary implementations of the method are described below.

[0018] According to one embodiment, in the step of calculating the acceleration of the motor output of the electric motor, a low-pass filtering of the calculated acceleration of the motor output of the electric motor is performed in order to eliminate high-frequency disturbances and noise.

[0019] According to one embodiment, only significant zero crossings are considered, wherein a significant zero crossing is determined if a zero crossing exceeds a predetermined slope, or if the acceleration has previously reached a predetermined threshold, preferably determined by a Schmitt trigger.

[0020] According to one embodiment, a plausibility check is performed during the step of detecting the impact event at the specified zero crossing. An impact event is considered plausible, in particular, if the rotational position of the electric motor's output shaft has increased by a predetermined minimum value between two impacts—that is, if it has increased at least to the point where an impact event can occur at all, given the mechanical properties of the impact mechanism—and / or if the rotational speed of the electric motor's output shaft is greater than zero, and / or if other measurement signals also indicate an impact event. According to one embodiment, the other measurement signals include a measured current of the electric motor, a detected trigger position, a detected duty cycle of an electrical voltage of the electric motor, and a detected torque of the electric motor.The trigger position can be a position of a control element of the impact rotary tool, with which the speed and / or the power of the impact rotary tool can be adjusted.

[0021] According to one embodiment, the step for measuring the rotational position and / or rotational speed of the motor output of the electric motor determines expected values ​​of the rotational position and / or rotational speed based on a predefined model of a drive train excluding the impact event, on the basis of which the acceleration of the motor output of the electric motor is calculated.

[0022] According to one embodiment, the step for measuring the rotational position and / or rotational speed of the electric motor's output shaft compensates for the effects of externally induced movements on the tool shaft on the rotational position and / or rotational speed, preferably by means of an inertial sensor. The externally induced movements may, for example, include a counter-torque generated by the user rotating the impact tool around a tool axis during use or by pressing the tool against a surface, and / or vibrations and accelerations, as well as all natural frequencies of the entire system consisting of the machine, the tool, consumables, and the user.

[0023] According to one embodiment, the rotational position and / or rotational speed of the motor output of the electric motor is detected by three Hall sensors or the current and voltage profile of rotor coils arranged around a rotor or motor output shaft of the electric motor at predetermined angular distances.

[0024] According to one embodiment, the impact tool is an impact wrench, a rotary hammer, a hammer drill, a chisel or a multi-tool.

[0025] According to one embodiment, the impact mechanism has a hammer weight driven directly or indirectly by the electric motor, rotatably, with at least one projection, and an anvil with at least one recess, rotatable with the hammer weight about a common axis of rotation and connected to the tool shaft and rotatably and / or axially displaceably mounted, wherein, when the hammer weight rotates relative to the anvil, the projection strikes the recess in such a way that the anvil, together with the tool shaft, is displaced in an impulse in the circumferential direction and optionally axially.

[0026] According to one embodiment of the device for detecting an impact event of a rotary impact tool, the rotary impact tool has a control device configured to receive the rotational position and / or rotational speed of the motor output as measured by the measuring device. The control device includes the calculation device, the determination device, and the detection device.

[0027] Exemplary embodiments of the present invention are described in detail below with reference to the following figures. Figure 1 Figure 1 schematically shows an impact turning tool in the form of an impact wrench according to an exemplary embodiment of the invention. Figure 2 shows a schematic view of a sensor arrangement for detecting a rotation angle or speed of the motor output of the electric motor of the impact rotary tool. Figure 1 . Figure 3shows rectangular waveforms of positive and negative impulses, which are detected by the three Hall effect sensors at the corresponding angle. Figure 4 This shows, as an example, the acceleration of the motor output of the electric motor over time, including the zero crossings from positive to negative. Figure 5 This shows an example of a significant zero crossing when a zero crossing exceeds a predetermined slope. Figure 6 This shows an example of a significant zero crossing when the acceleration has previously reached a predetermined threshold.

[0028] Identical or similar components in different figures are provided with the same reference numerals.

[0029] Figure 1Figure 1 schematically shows an impact wrench. The impact wrench has an electric motor 1, an impact mechanism, and a tool shaft 10. The impact mechanism is driven by the electric motor 1. Reference numeral 3 denotes a gearbox, preferably a planetary gearbox. An input of the gearbox 3 is connected to a motor output shaft 2 of the electric motor 1. An output of the gearbox 3 is connected to a spindle 4. The spindle 4 drives a rotating hammer 6, which transmits a torque via an anvil 11 to a tool shaft 10. As soon as the rotational resistance of the tool shaft 10 exceeds a predetermined value, an impact is delivered to the tool shaft 10 by an impact mechanism, which is described in more detail below, causing the tool shaft 10 to rotate abruptly or with an impulse.

[0030] The striking mechanism comprises the hammer 6 and the anvil 11. The hammer 6 has projections 8 which engage in complementary recesses 9 of the anvil 11 to transmit a torque. The reference numeral 7 denotes a V-shaped groove along which the hammer 6 is guided. The hammer 6 is biased towards the anvil 11 by a spring 5, in this case a compression spring arranged above the spindle 4, so that the projections 8 of the hammer 6 engage with the recesses 9 of the anvil 11. As soon as the rotational resistance of the tool shaft 10 exceeds the predetermined value, the hammer 6 is pushed away from the anvil 11 against the force of the spring 5 by the guidance of the V-shaped groove 7 (or alternatively by appropriate shaping of the projections 8 and the recesses 9) until the projections 8 disengage from the recesses 9. In this state, the hammer 6 is accelerated by the electric motor 1.As soon as the hammer 6 is pressed against the anvil 11 again by the spring 5 and the projections 8 engage with the recesses, the hammer 6 takes the anvil 11 with it, so that a blow is exerted on the anvil 11.

[0031] The motor output shaft 2 of the electric motor 1 or the spindle 4 can be considered as a motor output of the electric motor 1. Alternatively, a rotor or stator integrated into the electric motor 1 can be considered as the motor output of the electric motor 1.

[0032] The present invention is not limited to impact wrenches, but can also be applied to any impact rotary tool such as a rotary hammer, an impact drill, a chisel, or a multi-tool. In particular, the present invention can be applied to an impact rotary tool in which an impact mechanism comprises a hammer weight 6, rotatably driven directly or indirectly by the electric motor 1, with a hammer surface 8, and an anvil 11 with a recess 9, rotatable with the hammer weight 6 about a common axis of rotation and connected to the tool shaft 10 and rotatably and / or axially displaceably mounted, wherein, when the hammer weight 6 rotates relative to the anvil 11, the hammer surface 8 strikes against the recess 9 in such a way that the anvil 11, together with the tool shaft 10, is displaced in an impulse-like manner in the circumferential direction and optionally axially.

[0033] Figure 2Figure 1 shows a schematic view of a sensor arrangement for detecting the rotation angle or speed of the motor output 2, 4 of the electric motor 1. In the illustrated embodiment, the electric motor 1 is a brushless electric motor, which typically already has three integrated Hall effect sensors (Hall sensors) A, B, C arranged on the rotor or stator of the electric motor 1. The Hall sensors A, B, C are positioned at a distance of 120° from each other, corresponding to angular positions of 0°, 120°, 240° (and 360°). When the Hall sensors A, B, C come into contact with the magnetic field of the rotor, a corresponding digital pulse, either in the form of 1 or 0, is generated, as shown in the figure. Figure 3 The diagram shows that the Hall sensors A, B, and C are able to determine the motor position (angle) in six steps.

[0034] Figure 3The display shows rectangular waveforms of positive and negative pulses, detected at the corresponding angle by the three Hall-effect sensors A, B, and C. When the rotor magnet crosses one of the sensors A, B, or C, it generates a low signal (0) or a high signal (1), depending on whether it is the north or south pole of the rotor that has passed the sensor. As the rotor crosses all three sensors A, B, and C, the sensors A, B, and C toggle between low and high, thus indicating the rotor's position every 60 x N°, where N is the number of pole pairs. The falling or rising edges of the Hall sensor signals H1, H2, and H3 can indicate impact events.

[0035] Although the rotor poles are always arranged at a uniform angular distance, the Hall sensors A, B, and C may not necessarily be. Therefore, the rotor's rotation angle between two events is not always 60 x N°. However, the rotor's rotation angle between two rising or falling edges of the same Hall sensor signal should be 360 ​​x N°.

[0036] Impact detection is based on the measured rotational speed signal. When hammer 6 strikes anvil 11, it loses some of its kinetic energy, which compresses spring 5, indirectly connected to that of tool shaft 10. This spring exerts an opposing acceleration on motor output element 2, 4. After impact, the force of spring 5 increases, and via the V-shaped groove 7, the resulting torque increases as motor output element 2, 4 rotates. Once the sum of the spring and friction torque equals the electrical torque, the rotational speed also reaches a local maximum. Although there is a time lag between the local maximum of the motor output element 2, 4 signal and the impact, this is acceptable for the control algorithm. The impact event is assumed to have occurred after either the acceleration of motor output element 2, 4 reached a local maximum, i.e.,when the derivative of the acceleration has passed through a zero crossing, or when the acceleration itself has passed through a zero crossing.

[0037] The method for detecting an impact event of an impact rotary tool comprises the following steps: measuring a rotational position and / or a rotational speed of the motor output 2, 4 of the electric motor 1, which drives the tool shaft 10 via a gearbox 3 and the impact mechanism; calculating an acceleration of the motor output 2, 4 of the electric motor 1 based on the rotational position and / or the rotational speed of the motor output 2, 4 of the electric motor 1; determining zero crossings of the acceleration of the motor output 2, 4 of the electric motor 1; and detecting the impact event at a zero crossing determined above.

[0038] Figure 4The figure shows the acceleration a of the motor output 2, 4 of the electric motor 1 over time t, including the zero crossings from positive to negative, according to an example, which are marked by an arrow. The marked zero crossings simultaneously indicate the impact events. According to the Figure 4 The zero crossings of the acceleration a of the motor output 2, 4 of the electric motor 1 are determined. Alternatively, in the present invention, zero crossings of the (first) derivative of the acceleration a of the motor output 2, 4 of the electric motor 1 can be determined. The zero crossings of the derivative of the acceleration a determine the local maxima of the acceleration a, from which an impact event can also be derived. This also applies to the further Figure 5 and 6 The acceleration a can be replaced by the derivative of the acceleration a.

[0039] To reduce the noise component, in the step to calculate the acceleration of the motor output 2, 4 of the electric motor 1, a low-pass filtering of the calculated acceleration of the motor output 2, 4 of the electric motor 1 is preferably carried out, so that high-frequency components and noise are eliminated.

[0040] To improve the accuracy in detecting impact events, preferably only significant zero crossings are considered, whereby a significant zero crossing is determined if a zero crossing exceeds a predetermined steepness.

[0041] Figure 5Figure 1 shows an example of a significant zero crossing when a zero crossing exceeds a predetermined slope Δa / Δt. The slope Δa / Δt of the zero crossing can be determined if a difference Δa in the acceleration a during a time increment Δt exceeds the predetermined slope Δa / Δt. Alternatively, a slope angle α of the acceleration a with respect to the vertical axis a can be determined near or, preferably, at the zero crossing. The zero crossing is then significant if the slope angle α falls below a predetermined value, or if the tan α falls below a predetermined value.

[0042] To improve the accuracy in detecting impact events, preferably only significant zero crossings can be considered if the acceleration a has previously reached a predetermined threshold, preferably determined by means of a Schmitt trigger. Figure 6 This shows, for example, a significant zero crossing, where the acceleration a has previously reached a predetermined threshold A limit.

[0043] To further improve the accuracy of impact event detection, a plausibility check is preferably performed during the step of impact event detection at the specified zero crossing. An impact event is considered plausible, in particular, if the rotational position of the motor output 2, 4 of the electric motor 1 has increased by a predetermined minimum value between two impacts, and / or if the rotational speed of the motor output 2, 4 of the electric motor 1 is greater than zero. For example, the rotational position of the motor output 2, 4 of the electric motor 1 may have increased by a predetermined minimum value between two impacts to such an extent that an impact event can occur at all, given the mechanical properties of the impact mechanism.The plausibility check can alternatively or additionally determine that an impact event is plausible, particularly if other measurement signals also indicate an impact event. These other measurement signals can include a measured current of electric motor 1, a detected trigger position, a detected duty cycle of an electrical voltage of electric motor 1, and a detected torque of electric motor 1. The trigger position can be the position of a control element of the impact tool, which is used to adjust the speed and / or power of the impact tool.

[0044] The procedure can be improved by determining expected values ​​of the rotational position and / or rotational speed of the motor output 2, 4 of the electric motor 1 in the step for measuring the rotational position and / or rotational speed based on a pre-defined model of a drive train excluding the impact event, on the basis of which the acceleration of the motor output 2, 4 of the electric motor 1 is calculated.

[0045] The method can also be improved by compensating for the effects of externally induced movements on the tool shaft 10 on the rotational position and / or rotational speed of the motor output 2, 4 of the electric motor 1, preferably by means of an inertial sensor, in the step for measuring the rotational position and / or rotational speed. The externally induced movements can, for example, include a counter-torque generated by rotation of the impact tool about a tool axis by the user during use and / or by pressing the tool against a surface and / or by vibrations and accelerations as well as all natural frequencies of the acting overall system consisting of machine, tool, consumables and user.Externally induced movements of the tool around the tool shaft 10 cause a change in the relative angle of the tool to the anvil 11, without a change in the output angle relative to the environment / inertial frame. This can be compensated for by using the inertial sensor, for example an accelerometer and / or a gyroscope.

[0046] It should also be noted that "having" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference numerals in the claims are not to be considered as limitations. Reference symbol list

[0047] 1 Electric motor 2 Motor output shaft 3 Gearbox 4 Spindle 5 Spring 6 Hammer 7 Groove 8 Projection 9 Recess 10 Tool shaft 11 Anvil a Acceleration t Time α Steepness angle A limit Threshold A Hall sensor B Hall sensor C Hall sensor

Claims

1. A method for detecting an impact event of a rotary impact tool comprising a, preferably rotatable, tool shaft (10) which can be connected at its free end to a tool, and an impact mechanism configured to exert a rotary and / or axial impact on the tool shaft (10), wherein the method comprises: measuring a rotational position and / or a rotational speed of a motor output (2, 4) of an electric motor (1) which drives the tool shaft (10) via the impact mechanism; calculating an acceleration (a) of the motor output (2, 4) of the electric motor (1) based on the rotational position and / or the rotational speed of the motor output (2, 4) of the electric motor (1); determining zero crossings of the acceleration (a) of the motor output (2, 4) of the electric motor (1) or determining zero crossings of the derivative of the acceleration (a) of the motor output (2, 4) of the electric motor (1);and detection of the impact event at a previously determined zero crossing.

2. Method according to claim 1, wherein in the step of calculating the acceleration (a) of the motor output (2, 4) of the electric motor (1) a low-pass filtering of the calculated acceleration (a) of the motor output (2, 4) of the electric motor (1) is performed.

3. A method according to any of the preceding claims, wherein only significant zero crossings are considered as zero crossings, wherein a significant zero crossing is determined if a zero crossing exceeds a predetermined slope (Δa / Δt), or if the acceleration (a) previously exceeded a predetermined threshold (A limit ) has been reached, preferably determined by a Schmitt trigger.

4. A method according to one of the preceding claims, wherein in the step of detecting the impact event at the determined zero crossing a plausibility check is performed, wherein an impact event is determined to be plausible in particular if the rotational position of the motor output (2, 4) of the electric motor (1) has increased by a predetermined minimum value between two impacts, and / or if the rotational speed of the motor output (2, 4) of the electric motor (1) is greater than zero, and / or other measurement signals also indicate an impact event, wherein the other measurement signals preferably include a measured current of the electric motor (1), a detected trigger position, a detected duty cycle of an electrical voltage of the electric motor (1) and a detected torque of the electric motor (1).

5. Method according to one of the preceding claims, wherein the step of measuring the rotational position and / or rotational speed of the motor output (2, 4) of the electric motor (1) determines expected values ​​of the rotational position and / or rotational speed based on a model of a drive train excluding the impact event, on the basis of which the acceleration of the motor output (2, 4) of the electric motor (1) is calculated.

6. Method according to one of the preceding claims, wherein the step for measuring the rotational position and / or rotational speed of the motor output (2, 4) of the electric motor (1) compensates for the effects of externally induced movements on the tool shaft (10) on the rotational position and / or rotational speed, preferably by means of an inertial sensor.

7. Method according to one of the preceding claims, wherein the rotational position and / or the rotational speed of the motor output (2, 4) of the electric motor (1) is detected by three Hall sensors (A, B, C) or a current and voltage profile of rotor coils arranged around a rotor or a motor output shaft (2) of the electric motor (1) at predetermined angular distances.

8. Method according to any of the preceding claims, wherein the impact rotary tool is an impact wrench, a rotary hammer, a hammer drill, a chisel or a multi-tool.

9. Method according to one of the preceding claims, wherein the impact mechanism comprises a hammer weight (6) rotatably driven directly or indirectly by the electric motor (1) with at least one projection (8) and an anvil (11) rotatable with the hammer weight (6) about a common axis of rotation and connected to the tool shaft (10) and rotatably and / or axially displaceably mounted with at least one recess (9), wherein the projection (8) strikes against the recess (9) when the hammer weight (6) rotates relative to the anvil (11) in such a way that the anvil (11) together with the tool shaft (10) is displaced in an impulse in the circumferential direction and optionally axially.

10. Device for detecting an impact event of a rotary impact tool with a, preferably rotatable, tool shaft (10) which can be connected to a tool at its free end, and an impact mechanism configured to exert a rotary and / or axial impact on the tool shaft (10), wherein the device comprises: a measuring device configured to measure a rotational position and / or a rotational speed of a motor output (2, 4) of an electric motor (1) which drives the tool shaft (10) via the impact mechanism; a calculation device configured to calculate an acceleration (a) of the motor output (2, 4) of the electric motor (1) based on the rotational position and / or the rotational speed of the motor output (2, 4) of the electric motor (1);a determining device configured to determine zero crossings of the acceleration (a) of the motor output (2, 4) of the electric motor (1) or zero crossings of the derivative of the acceleration (a) of the motor output (2, 4) of the electric motor (1); and a detection device configured to detect the impact event at a zero crossing determined above.

11. Device for detecting an impact event of a rotary impact tool according to the previous claim, wherein the measuring device has three Hall sensors (A, B, C) arranged around a rotor or motor output shaft (2) of the electric motor (1) at predetermined angular distances.

12. Device for detecting an impact event of an impact rotary tool according to claim 10 or 11, wherein the impact rotary tool has a control device configured to receive the rotational position and / or rotational speed of the motor output (2, 4) measured by the measuring device, and which includes the calculation device, the determination device and the detection device.

13. Device for detecting an impact event of an impact rotary tool according to one of claims 10 to 12, wherein the impact rotary tool is an impact wrench, a rotary hammer, an impact drill, a chisel or a multi-tool.

14. Device for detecting an impact event of a rotary impact tool according to one of claims 10 to 13, wherein the impact mechanism comprises a hammer weight (6) rotatably driven directly or indirectly by the electric motor (1) with at least one projection (8) and an anvil (11) rotatable with the hammer weight (6) about a common axis of rotation and connected to the tool shaft (10) and rotatably and / or axially displaceably mounted with at least one recess (9), wherein the projection (8) strikes against the recess (9) when the hammer weight (6) rotates relative to the anvil (11) in such a way that the anvil (11) together with the tool shaft (10) is displaced in an impulse in the circumferential direction and optionally axially.

15. Impact rotary tool with a device for detecting an impact event according to one of claims 10 to 14.

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