Startup mode for power tools

Abstract

The present invention relates to a power tool (2), in particular a handheld power tool, for example a grinding machine, comprising a tool (5), an electric motor (6) for driving the tool (5), and a control unit (7) for controlling the electric motor (6) by means of a motor current (MI), wherein the control unit (7) has a start-up mode, in which the control unit (7) controls the electric motor (6) so that during the start-up mode the electric motor (6) goes through a speed ramp (DR) along which the speed of the electric motor (6) is continuously increased up to an operating speed (ADZ), and the control unit (7) is configured to adjust the slope of the speed ramp (DR) for the start-up mode based on a detected temperature and / or to adjust the intensity of the motor current (MI) for the start-up mode based on the detected temperature / the detected temperature.

Description

[Technical Field]

[0001] The present invention relates to a power tool, particularly a handheld power tool, such as a grinding machine, including a tool, an electric motor for driving the tool, and a control unit for controlling the electric motor with a motor current. The control unit has a start-up mode, and in the start-up mode, the control unit controls the electric motor so that the electric motor goes through a speed ramp during the start-up mode, and the speed of the electric motor is continuously increased along the speed ramp to an operating speed. For example, in the start-up mode, the control unit continuously increases the frequency of the motor current, thereby achieving a continuous increase in the electric motor speed. [Background technology]

[0002] Once the operating speed is reached, the power tool is preferably controlled using a sensorless principle, in particular using the back EMF principle. EMF stands for Electromotive Force (Electromotorische Kraft). The power tool preferably does not include a position sensor for detecting the current rotor angle of the electric motor. The control unit detects the current rotor angle and / or the current rotational speed of the electric motor in a sensorless manner, for example based on the electrical magnitude of the electric motor, in particular the current (e.g., motor current) and / or voltage. Once the operating speed is reached, the power tool performs commutation of the electric motor based on the (in particular sensorless) detected current rotor angle and / or the (in particular sensorless) detected current rotational speed.

[0003] Before the operating speed is reached, i.e. in start-up mode, the control unit preferably does not use the sensorless principle, since for example the sensorless principle only functions from a certain minimum speed, the operating speed.

[0004] The speed ramp is set for the start-up mode so that the electric motor can execute the speed ramp under various conditions, in particular under various strong internal mechanical loads acting on the electric motor, which internal mechanical loads to be taken into account when setting the speed ramp are, in particular, the moment of inertia acting against the drive of the rotor.

[0005] It is important to avoid a situation where the electric motor's rotor can no longer follow the electric field provided by the electric motor based on the motor current (e.g., due to an excessively steep speed ramp in start-up mode), resulting in a failed start-up of the electric motor. In particular, if the current rotor angle and / or current speed cannot be detected and / or taken into account during start-up mode, it is generally impossible to identify that the electric motor is accelerating too slowly with respect to the current speed ramp (e.g., due to internal mechanical loads). Therefore, it is generally impossible to address such a situation during start-up mode by reducing the slope of the speed ramp and / or increasing the motor current. For this reason, the speed ramp must be set sufficiently flat in advance so that the electric motor can follow the speed ramp even with a large internal mechanical load. A flat speed ramp makes start-up mode take longer, among other things. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to improve the start-up mode. [Means for solving the problem]

[0007] This problem is solved by a power tool according to claim 1. The control unit of the power tool is configured to adjust the slope of the rotation speed ramp for the start-up mode based on the detected temperature and / or to adjust the current intensity of the motor current for the start-up mode based on the detected temperature.

[0008] The internal mechanical loads acting against the tool drive, i.e., in particular the moment of inertia, are temperature-dependent. The magnitude of the internal mechanical load can be estimated via the detected temperature, and the speed ramp can be adapted to the internal mechanical load. Therefore, the speed ramp does not always have to be set to the "worst case," i.e., the maximum internal mechanical load, but can be adapted to the current internal mechanical load present according to the detected temperature. This allows the start-up mode to be performed quickly, especially when the maximum internal mechanical load is not present.

[0009] Advantageous developments are the subject of the dependent claims.

[0010] The invention further relates to a system comprising a power tool and a portable device capable of configuring activation modes.

[0011] The present invention further relates to a method for providing a start-up mode for a tool and a power tool including an electric motor for driving the tool, wherein the electric motor goes through a speed ramp during the start-up mode, along which the speed of the electric motor is continuously increased up to an operating speed, the method comprising the steps of detecting a temperature, adjusting the slope of the speed ramp for the start-up mode based on the detected temperature and / or adjusting the current intensity of the motor current for the start-up mode based on the detected temperature, and providing a start-up mode with the adjusted slope of the speed ramp and / or the adjusted intensity of the motor current.

[0012] The invention further relates to an assembly comprising an electric motor for driving a tool and a control unit for controlling the electric motor by means of a motor current, the control unit having a start-up mode, in which the control unit controls the electric motor such that during the start-up mode the electric motor goes through a speed ramp and beside the speed ramp the speed of the electric motor is continuously increased up to an operating speed, the control unit being configured to adjust the slope of the speed ramp for the start-up mode based on a detected temperature and / or to adjust the intensity of the motor current for the start-up mode based on the detected temperature / said detected temperature.

[0013] The invention further relates to a computer program product comprising instructions for causing a power tool to perform the method steps.

[0014] The invention further relates to a computer readable medium having a computer program stored thereon.

[0015] The present invention further relates to a method comprising playing a computer program product on a power tool.

[0016] Further exemplary details as well as exemplary embodiments are described below with reference to the drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of a system including a power tool, a portable device, and a workpiece. [Figure 2] 1 is a schematic view of a head portion of a power tool. [Figure 3] 1 is a schematic diagram of an electric motor, a control unit, a temperature sensor, and an operating device of a power tool. [Figure 4] This is a graph showing two RPM ramps with different slopes. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1 shows a system 1 including a power tool 2, a workpiece 3 and an optional portable device 4. The system 1 is a purely exemplary application environment for the power tool 2. The power tool 2 can also be provided on its own, i.e., without further components of the system 1.

[0019] The power tool 2 is exemplarily a handheld power tool. The power tool 2 can be held, supported, and / or guided by a user with one or both hands. Exemplarily, the power tool 2 is a grinding machine, in particular an orbital sander. Exemplarily, the power tool 2 is a long-neck sander, in particular a long-neck orbital sander. The power tool 2 may also be designed as an eccentric polisher.

[0020] The power tool 2 includes a tool 5, which is illustratively designed as a grinding tool, in particular a grinding disk. The power tool 2 further includes an electric motor 6 for driving the tool 5. The electric motor 6 is illustratively designed as an electronic commutator, in particular as a sensorless commutated electric motor. In particular, the electric motor 6 is designed as a brushless direct current motor (BLDC motor). The electric motor 6 provides the driving rotational movement, on the basis of which the tool 5 is subjected to a working movement.

[0021] The power tool 2 further includes a control unit 7 for controlling the electric motor 6 with a motor current MI. The control unit 7 has a start-up mode in which the control unit 7 controls the electric motor 6 so that during the start-up mode the electric motor 6 passes through a speed ramp DR along which the speed of the electric motor 6 is continuously increased up to the operating speed ADZ. An exemplary speed ramp DR is shown in Figure 4.

[0022] The control unit 7 is configured to adjust the slope of the rotation speed ramp DR for the start-up mode based on the detected temperature and / or to adjust the current intensity of the motor current MI for the start-up mode based on the detected temperature, where the current intensity of the motor current MI means in particular the amplitude of the motor current MI.

[0023] Illustratively, power tool 2 includes a head portion 8 that includes tool 5. Head portion 8 preferably includes electric motor 6. In an alternative configuration, electric motor 6 may be located in another portion of power tool 2, such as user portion 9. Optionally, head portion 8 includes a head portion temperature sensor 10, which may be referred to as a second temperature sensor.

[0024] Exemplarily, the power tool 2 comprises a user part 9. The user part 9 comprises, in particular, a grip part 11, which is grasped by the user's hand and can support and / or guide the power tool 2. Exemplarily, the user part 9 comprises an operating device 12, via which the driving of the tool 5 by the electric motor 6 can be switched on and / or off and / or a target rotation speed can be set for the electric motor 6. In particular, the operating device 12 comprises a first operating element 14, in particular designed as a switch, preferably via which the driving of the tool 5 by the electric motor 6 can be switched on and / or off. Exemplarily, the operating device 12 comprises a second operating element 16, in particular designed as a rotating wheel, preferably via which a target rotation speed can be set for the electric motor 6.

[0025] The user part 9 further exemplarily includes a control unit 7. In an alternative configuration, the control unit 7 may be located in another part of the power tool 2, in particular in the head part 8. The power tool 2, in particular the user part 9, includes a user part temperature sensor 18, which may be referred to as a first temperature sensor.

[0026] The power tool 2 is preferably configured to detect the temperature (based on which the slope of the rotation speed ramp DR and / or the intensity of the motor current MI are adjusted) by a first temperature sensor 18. The first temperature sensor 18 is exemplarily arranged at a distance from the electric motor 6. In particular, the first temperature sensor 18 is exemplarily arranged at a distance and / or thermally insulated from the electric motor 6, so that the temperature detected by the first temperature sensor 18 is preferably not affected by heat emitted from the electric motor 6. Exemplarily, the electric motor 6 is arranged on a first side of the neck portion 22, and the first temperature sensor 18 is arranged on a second side of the neck portion 22 opposite the electric motor 6.

[0027] Optionally, the user portion 9 has a pipe connection 19 to which a suction pipe can be connected. The pipe connection 19 is in fluid communication with a suction opening in the head portion 8 via an air channel extending through the power tool 2.

[0028] The user part 9 exemplarily has a user part casing 20. In the user part casing 20, in particular the control unit 7 and / or the first temperature sensor 18 are arranged. In the user part casing 20, an operating device 12, in particular the first operating element 14 and / or the second operating element 16, is exemplarily arranged. In the user part casing 20, a grip part 11 is exemplarily attached. In the grip part 11, a pipe connection 19 is exemplarily attached.

[0029] The head part 8 exemplarily comprises a head part casing 21 in which, inter alia, the electric motor 6 and / or the head part temperature sensor 10 are arranged.

[0030] According to one possible configuration, the control unit 7 is configured to determine a temperature based on which the control unit 7 adjusts the gradient of the rotation speed ramp DR and / or the intensity of the motor current for the start-up mode by means of a plurality of temperature sensors, in particular by means of a first temperature sensor 18 and a second temperature sensor. In particular, the control unit 7 detects a first temperature value by means of the first temperature sensor 18 and a second temperature value by means of the second temperature sensor, and adjusts the gradient of the rotation speed ramp DR and / or the intensity of the motor current for the start-up mode based on the first and second temperature values. For example, the control unit calculates the temperature based on which the control unit 7 adjusts the gradient of the rotation speed ramp DR and / or the intensity of the motor current for the start-up mode from the first and second temperature values, for example as an average value.

[0031] The power tool 2 exemplarily comprises a neck portion 22, which preferably comprises, in particular, a rod-shaped neck element 24. The neck portion 22, in particular the neck element 24, connects the head portion 8, in particular the head portion casing 21, with the user part 9, in particular the user part casing 20. An electrical conductor 27 preferably extends through the neck portion 22, in particular the neck element 24, via which the control unit 7 supplies the motor current MI to the electric motor 6. Furthermore, preferably, the air channel extends through the neck portion 22, in particular the neck element 24.

[0032] The power tool 2 preferably has a longitudinal basic configuration extending in the longitudinal direction. Illustratively, the neck portion 22, and in particular the neck element 24, is at least 30%, at least 40%, or at least 50% of the longitudinal extension of the power tool 2.

[0033] 1 exemplarily has a workpiece surface 24 that can be processed, in particular ground and / or polished, by a tool 5. The workpiece 3 is, for example, a wall, in particular a ceiling wall and / or a side wall, of a building. The surface of the wall is ground by the tool 5, in particular a grinding plate.

[0034] The mobile device 4 is preferably designed as a smartphone or a tablet and is particularly adapted to communicate with the power tool 2, in particular the control unit 7, preferably wirelessly, for example via Bluetooth, NFC, WLAN and / or mobile radio.

[0035] 2 shows an exemplary detailed view of the head portion 8. The electric motor 6 includes a stator 25 and a rotor 26 that can be driven to rotate relative to the stator 25. The rotor 26 is supported so as to be rotatable about a rotor rotation axis 28. The driven rotation of the rotor 26 occurs about this rotor rotation axis 28.

[0036] The rotor 26 includes an eccentric part 29 that is eccentrically disposed relative to the rotor rotation axis 28. When the rotor 26 performs its driving rotational movement about the rotor rotation axis 28, the eccentric part 29 moves along a circular path about the rotor rotation axis 28. The tool 5 is coupled to the eccentric part 29, and thus the movement of the eccentric part 29 causes the tool 5 to perform a working movement. Exemplarily, the power tool 2 includes a rotary bearing 30, via which the tool 5 is coupled to the eccentric part 29. The rotary bearing 30 defines a tool rotation axis 33 about which the tool 5 can rotate relative to the eccentric part 29. Exemplarily, the tool rotation axis 33 extends through the center of the tool 5 configured as a grinding disk. The tool rotation axis 33 is oriented, in particular, parallel to the rotor rotation axis 28 and is disposed offset therefrom. Because the tool 5 is rotatably supported relative to the eccentric part 29, the tool 5 can also perform unconstrained rotation, in particular as a working movement. In unconstrained rotation, the natural rotation of the tool 5, i.e. the rotation of the tool 5 about the tool rotation axis 33, is preferably independent of the driven rotational motion.

[0037] The power tool 2, in particular the head portion 8, preferably further comprises a brake device 34, which is configured to brake the tool 5, in particular relative to a station portion 36 of the power tool 2. The brake device 34 may also be referred to as a disc brake. The brake device 34 is used to slow down the automatic rotation of the tool 5 (relative to the station portion 36), in particular when the power tool 3 is idling, i.e. when the tool 5 is not yet in contact with the workpiece 3, in particular the workpiece surface 24. By slowing down the automatic rotation of the tool 5, it is possible to reduce or prevent the formation of scratches that occur when the tool 5 is placed on the workpiece 3, in particular the workpiece surface 24.

[0038] The station part 36 is fixed, in particular relative to the stator 25 and / or the head part casing 21. The station part 36 does not follow the driving rotational movement. The station part 36 is designed, for example, in the shape of a disk and preferably has a through-hole 38 through which the rotor 26, in particular the eccentric part 29, is guided out.

[0039] The braking device 34 exemplarily includes a braking element 37, which is arranged, in particular, between the tool 5 and the station part 36. The braking element 37 is designed, in particular, to be elastic and / or ring-shaped. The braking element 37 is designed, in particular, as a rubber ring, preferably as a ring-shaped rubber sleeve. The braking element 37 is, in particular, a diaphragm and / or a thin plate. The braking element 37 orbits the tool rotation axis 33. The braking element 37 is preferably fixed to the tool 5 and therefore moves together with the tool 5, in particular, performs a working movement together with the tool 5. The braking element 37 preferably rubs against the station part 36, thereby braking the tool 5 relative to the station part 36. According to another embodiment, the braking element 37 is fixed to the station part 36 and rubs against the tool 5, thereby braking the tool 5 relative to the station part 36.

[0040] The tool 5 is designed, in particular, as a grinding disk. The tool 5 has, in particular, a disk-shaped upper tool side 40 and / or a disk-shaped lower tool side 42. The upper tool side 40 and / or the lower tool side 42 are preferably oriented perpendicular to the tool rotation axis 33. The upper tool side 40 is preferably in contact with a brake element 37. For example, the brake element 37 is fixed to the upper tool side 40. Alternatively, the brake element 37 rubs against the upper tool side 40. The lower tool side 42 is preferably formed by a grinding means, in particular by a grinding disk. The power tool 2 abuts, with the lower tool side 42, against the workpiece 3, in particular against the workpiece surface 24, thereby machining, in particular grinding, the workpiece 3.

[0041] FIG. 3 shows diagrammatically the electric motor 6 , the control unit 7 , the first temperature sensor 18 and the operating device 12 .

[0042] The control unit 7 exemplarily includes a calculation unit 44 and a power unit 46. The calculation unit 44 is particularly designed as a microcontroller and preferably includes a processor. The power unit 46 is particularly designed as a power electronic circuit. The calculation unit 44 calculates control information AI, on the basis of which the power unit 46 controls the electric motor 6. In particular, the power unit 46 provides a motor current MI based on the control information AI.

[0043] Exemplarily, the motor current MI includes three motor currents, namely, a first motor current MI1, a second motor current MI2, and a third motor current MI3. The control information AI preferably sets the frequency, amplitude, and / or phase for the motor currents MI1, MI2, MI3. The electric conductor extending from the control unit 7 to the electric motor 6 preferably includes three cores, namely, a first core 51, a second core 52, and a third core 53, through which the respective motor currents MI1, MI2, MI3 are transmitted.

[0044] The electric motor 6, and in particular the stator 25, has a plurality of coils 55. Each coil 55 is energized with a respective motor current MI1, MI2, MI3 to drive the rotor 26 into rotational movement. The electric motor 6, and in particular the rotor 26, has permanent magnets 56 which preferably magnetically interact with the magnetic field provided by the coils 55, thereby causing the rotor 26 to move in rotational movement.

[0045] The control unit 7 has the aforementioned start-up mode and working mode, which are described in more detail below.

[0046] In the working mode, the rotor 26 rotates at an actual speed, in particular at or above the operating speed ADZ, which is preferably equal to the target speed, and the working movement of the tool 5 is fast enough to machine the workpiece 3.

[0047] The control unit 7 is configured to control the electric motor 6 in the work mode using a sensorless principle to detect the current rotor angle and / or the current rotational speed of the electric motor 6. In particular, the control unit 7 is configured to commutate the electric motor sensorlessly, i.e. based on the sensorless principle, in particular the back EMF principle, in the work mode. Preferably, the power tool 2 does not have a position sensor for detecting the current rotor angle and / or the current rotational speed of the electric motor 6.

[0048] For example, the control unit 7 detects the current rotor angle and / or current rotation speed of the electric motor 6 based on the reverse voltage formed in the coil 55 (which can be extracted in particular via the electrical conductor 27), and performs commutation of the electric motor 6 based on the current rotor angle and / or current rotation speed, for example by means of motor currents MI1, MI2, MI3.

[0049] In particular, the control unit 7 performs a speed control in the working mode, in which the control unit 7 adapts the motor currents MI1, MI2, MI3, in particular their frequency and / or current intensity, so that the current speed of the electric motor 6, detected (in particular without a sensor), corresponds to a target speed, input in particular via the operating device 12. For example, the calculation unit 44 calculates control information AI for the power unit 46 based on the target speed, the current speed detected (in particular without a sensor) and / or the current rotor angle detected (in particular without a sensor), and the power unit 46 provides the motor currents MI1, MI2, MI3 based on the control information AI. The control information AI sets, for example, the frequency, phase and / or current intensity of the motor currents MI1, MI2, MI3.

[0050] For example, the sensorless principle for detecting the current rotor angle and / or current rotational speed only functions once a minimum rotational speed, i.e., operating rotational speed ADZ, of the rotor 26 has been reached, below which the sensorless principle does not function.

[0051] To reach the operating speed ADZ, the control unit 7 has a start-up mode in which the control unit 7 can increase the rotational speed of the rotor 26 to a minimum rotational speed (e.g., starting from a stationary state of the rotor 26) without detecting and / or taking into account the rotor angle and / or rotational speed. The control unit 7 is preferably configured to control the electric motor 6 in the start-up mode without detecting and / or taking into account the current rotor angle and / or current rotational speed of the electric motor 6. In the start-up mode, in particular, "open-loop control" is performed, i.e., the rotational speed of the rotor 26 is regulated purely (without closed-loop control). The rotational speed ramp DR is not controlled in a closed-loop manner. Preferably, the control unit 7 pre-determines the slope and / or current intensity for the start-up mode. In particular, the control unit 7 does not adapt the slope of the rotational speed ramp and / or change the current intensity, in particular the amplitude, of the motor current MI during the course of the rotational speed ramp.

[0052] FIG. 4 shows a graph plotting the rotational speed DZ of the rotor 26 against time t. The graph includes a first rotational speed ramp DR1 and a second rotational speed ramp DR2 as examples of rotational speed ramps DR. The explanations related to the rotational speed ramp DR preferably apply to the first rotational speed ramp DR1 and / or the second rotational speed ramp DR2. The rotational speed ramp DR preferably rises monotonically, in particular very monotonically. Exemplarily, the rotational speed ramp DR is linear. The rotational speed ramp DR has a constant slope. The rotational speed ramp DR preferably starts at rotational speed 0 and extends at least to the operating rotational speed ADZ. The rotational speed ramp DR preferably includes a time sequence of rotational speed values. The rotational speed values ​​are shown as dots on the rotational speed ramps DR1 and DR2 in FIG. 4. The control unit 7 is configured, in particular, to provide respective control information AI for each rotational speed value and to provide respective motor currents MI1, MI2, and MI3 based on the respective control information AI. Preferably, the control unit 7 is configured to provide motor currents MI1, MI2, MI3 with successively increasing frequencies such that the rotational speed of the rotor 26 increases successively according to the rotational speed ramp DR.

[0053] Preferably, the rotational speed ramp DR is completely set in the control unit 7 already before the start of the rotational speed ramp DR, i.e., before the control unit 7 controls the electric motor 6 according to the rotational speed ramp DR. For example, the rotational speed ramp DR, in particular the rotational speed values ​​of the rotational speed ramp DR, are stored in the control unit 7, preferably before the control unit 7 controls the electric motor 6 according to the rotational speed ramp DR. Furthermore, it is possible to store ramp information in the control unit 7 (in particular before the start of the rotational speed ramp DR), by means of which the rotational speed ramp DR is set. For example, the ramp information sets the gradient of the rotational speed ramp DR. In particular, the ramp information includes, for example, a ramp increment RI that describes the rotational speed difference between two rotational speed values ​​that are immediately successive in time in the rotational speed ramp DR. Preferably, the rotational speed values ​​are each equally spaced apart in time.

[0054] The control unit 7 is preferably configured to switch from start-up mode to work mode once the operating speed ADZ is reached and to control the electric motor 6 in the work mode using a sensorless principle, in particular the back EMF principle, to detect the current rotor angle and / or the current rotational speed of the electric motor 6. In particular, the control unit 7 performs speed control once the operating speed ADZ is reached. If the target rotational speed SDZ is greater than the operating speed ADZ, the speed can be further increased in the work mode after the operating speed ADZ is reached until the target rotational speed SDZ is reached. The further increase can, for example, be performed with the same gradient as the speed ramp described above or with a different gradient.

[0055] The internal mechanical loads acting on the rotor 26 oppose the increase in the rotational speed of the rotor 26 and must be overcome during the start-up mode in order to allow the rotational speed of the rotor 26 to increase to the operating rotational speed ADZ. The internal mechanical loads acting on the rotor 26 are particularly temperature dependent, and illustratively decrease with increasing temperature and increase with decreasing temperature.

[0056] By way of example, the temperature-dependent internal mechanical load is the moment of inertia acting on the rotor 26. This moment of inertia depends in particular on the braking action, preferably on the braking force, of the brake device 34. If the braking action, in particular on the braking force, is increased, the moment of inertia acting on the rotor 26 is smaller than in the case of a weak braking action, in particular on a weak braking force. This is in particular because the tool 5 does not rotate as fast about the tool rotation axis 33 due to the strong braking action (in particular not faster than the rotational speed of the rotor 26). If the braking action, in particular on a weak braking force, is decreased, the moment of inertia acting on the rotor 26 is larger than in the case of a strong braking action, in particular on a strong braking force. This is in particular because the tool 5 rotates faster about the tool rotation axis 33 due to the weak braking action (for example at the rotational speed of the rotor 26).

[0057] The braking action, particularly the braking force, of the brake device 34 is illustratively temperature dependent, e.g., the coefficient of friction of the friction provided by the brake element 37 is temperature dependent, e.g., the braking action, particularly the braking force, preferably the coefficient of friction, increases with increasing temperature and decreases with decreasing temperature.

[0058] The control unit 7 is preferably arranged to take this temperature dependency into account and in particular to compensate for it during the start-up mode.

[0059] The control unit 7 is configured to adjust the gradient of the rotation speed ramp DR based on the detected temperature. For example, the control unit 7 is preferably configured to adjust the gradient of the rotation speed ramp DR to be relatively large when the detected temperature is relatively high, and to adjust the gradient of the rotation speed ramp DR to be relatively small when the detected temperature is relatively low.

[0060] The control unit 7 is configured to selectively adjust the first rotation speed ramp DR1 with a first gradient or the second rotation speed ramp DR2 with a second gradient based on the detected temperature, and to use the adjusted rotation speed ramp in the start-up mode, where the second gradient is illustratively smaller than the first gradient.

[0061] In particular, the control unit 7 is configured to adjust the first rotation speed ramp DR1 for the start-up mode in response to the detected temperature being in a first temperature range, and to adjust the second rotation speed ramp DR2 for the start-up mode in response to the detected temperature being in a second temperature range. The temperatures included in the first temperature range are preferably higher than the temperatures included in the second temperature range. The first and second temperature ranges preferably do not overlap.

[0062] Preferably, the first rotational speed ramp DR1 and the second rotational speed ramp DR2 are fully configured in the control unit 7, in particular before the start-up mode is executed. For example, the rotational speed ramps DR1 and DR2, in particular the respective rotational speed values ​​of the rotational speed ramps DR1 and DR2, are stored in the control unit 7, preferably before the control unit 7 controls the electric motor 6 according to the selected rotational speed ramp. It is also possible to store first and second rotational speed ramp information in the control unit 7 (in particular before controlling the electric motor 6 according to the adjusted rotational speed ramp). The first rotational speed ramp information defines the first rotational speed ramp DR1, in particular its gradient, and the second rotational speed ramp information defines the second rotational speed ramp DR2, in particular its gradient. Exemplarily, the first rotational speed ramp information includes a first rotational speed increment RI1, and the second rotational speed ramp information includes a second rotational speed increment RI2. The first rotational speed increment RI1 describes the rotational speed difference between, for example, two rotational speed values ​​immediately successive in time in the first rotational speed ramp DR1. The second ramp increment RI2 describes the speed difference between, for example, two immediately successive speed values ​​in the second speed ramp DR2. The first ramp increment RI1 is illustratively larger than the second ramp increment RI2.

[0063] Preferably, the control unit 7 is configured to selectively select the first lamp information or the second lamp information based on the detected temperature, and generate a rotation speed ramp for the start-up mode based on the selected lamp information.

[0064] The control unit 7 is preferably configured to adjust the current intensity of the motor current MI based on the detected temperature, in particular instead of or in addition to adjusting the slope of the rotation speed ramp DR based on the detected temperature as described above.

[0065] Preferably, the control unit 7 is configured to adjust the motor current MI with a relatively small current intensity, in particular a relatively small amplitude, when the detected temperature is relatively high, and to adjust the motor current MI with a relatively large current intensity, in particular a relatively large amplitude, when the detected temperature is relatively low. In particular, the control unit 7 is configured to adjust the first motor current MI1, the second motor current MI2, and the third motor current MI3 with a relatively large current intensity, in particular a relatively large amplitude, when the detected temperature is relatively high, and with a relatively small current intensity, in particular a relatively small amplitude, when the detected temperature is relatively low.

[0066] In particular, the control unit 7 is configured to set the current intensities, particularly amplitudes, of the motor currents MI1, MI2, MI3 to a first value in response to the detected temperature being in a first temperature range, and to set the current intensities, particularly amplitudes, of the motor currents MI1, MI2, MI3 to a second value in response to the detected temperature being in a second temperature range. The second value is preferably greater than the first value. The temperatures included in the first temperature range are preferably higher than the temperatures included in the second temperature range. The first and second temperature ranges preferably do not overlap.

[0067] The start-up mode can preferably be configured via the mobile device 4. For example, via the mobile device 4, temperature considerations can be activated and / or deactivated, in particular by user input, when adjusting the slope of the rotational speed ramp DR and / or the intensity of the motor current MI. Furthermore, via the mobile device 4, it is preferably possible to adjust the slope of the rotational speed ramp DR and / or the intensity of the motor current MI, in particular by user input.

[0068] Alternatively or additionally, it is preferably possible to configure the activation mode via the operating device 12, in particular as described above.

[0069] Preferably, the power tool 2 is driven according to the following method.

[0070] In a first step, the power tool 2 is switched on, in particular via the operating device 12 .

[0071] In a second step, a first temperature is detected, in particular by the first temperature sensor 18. The detected first temperature is in particular the ambient temperature of the power tool 2. The detected first temperature is preferably not the motor temperature of the rotating electric motor.

[0072] In a third step, the control unit 7 adjusts the first slope of the rotation speed ramp DR for the start-up mode based on the detected first temperature. Alternatively or additionally, the control unit 7 adjusts the first current strength, in particular the first amplitude, of the motor current MI for the start-up mode based on the detected first temperature.

[0073] In a fourth step, the control unit 7 provides a start-up mode with an adjusted first gradient of the rotational speed ramp DR and / or an adjusted first current intensity of the motor current MI. The rotational speed of the rotor 26 is increased according to the rotational speed ramp DR, in particular until the operating rotational speed ADZ is reached.

[0074] In an optional fifth step, the power tool 2 is switched off (in particular via the operating device 12) and the rotational speed of the rotor 26 drops below the operating rotational speed ADZ.

[0075] In an optional sixth step, the power tool 2 is switched on again.

[0076] In an optional seventh step, a second temperature is detected, in particular by the first temperature sensor 18. The second temperature detected in the seventh step is illustratively different from the first temperature detected in the second step.

[0077] In an optional eighth step, the control unit 7 adjusts a second slope of the rotation speed ramp DR for the start-up mode based on the detected second temperature. Alternatively or additionally, the control unit 7 adjusts a second current intensity, in particular a second amplitude, of the motor current MI for the start-up mode based on the detected second temperature. The second slope and / or the second current intensity adjusted in the eighth step are preferably different from the first slope and / or the first current intensity adjusted in the third step.

[0078] In an optional ninth step, the control unit 7 provides a start-up mode with an adjusted second slope of the rotational speed ramp DR and / or an adjusted second current intensity of the motor current MI. The rotational speed of the rotor 26 is increased according to the rotational speed ramp DR until it reaches at least the operating rotational speed ADZ.

[0079] The steps are in particular carried out in chronological order, i.e. in the order described above. The present application relates to the invention described in the claims, but may also include the following configurations as other aspects. 1. 1. A power tool (2), in particular a handheld power tool, such as a grinding machine, comprising: a tool (5), an electric motor (6) for driving the tool (5), and a control unit (7) for controlling the electric motor (6) by a motor current (MI), wherein the control unit (7) has a start-up mode, in which the control unit (7) controls the electric motor (6) so that the electric motor (6) passes through a rotation speed ramp (DR) during the start-up mode and the rotation speed of the electric motor (6) is continuously increased along the rotation speed ramp (DR) up to an operating rotation speed (ADZ), and the control unit (7) is configured to adjust the slope of the rotation speed ramp (DR) for the start-up mode based on a detected temperature and / or adjust the intensity of the motor current (MI) for the start-up mode based on the detected temperature. 2. The power tool (2) described in claim 1, wherein the control unit (7) is configured to adjust the gradient of the rotation speed ramp (DR) to be relatively large when the detected temperature is relatively high, and to adjust the gradient of the rotation speed ramp (DR) to be relatively small when the detected temperature is relatively low. 3. The power tool (2) according to claim 1 or 2, wherein the control unit (7) is configured to adjust the motor current (MI) to a relatively small current intensity when the detected temperature is relatively high, and to adjust the motor current (MI) to a relatively large current intensity when the detected temperature is relatively low. 4. The power tool (2) according to any one of claims 1 to 3, wherein the control unit (7) is configured to switch from the start-up mode to a work mode when the operating speed (ADZ) is reached, and to control the electric motor (6) in the work mode using a sensorless principle, in particular using the back EMF principle, to detect a current rotor angle and / or a current rotation speed of the electric motor (6). 5. The power tool (2) according to any one of 1 to 4 above, wherein the control unit (7) is configured to control the electric motor (6) in the start-up mode without detecting or taking into account the rotor angle of the electric motor (6) and / or the rotation speed of the electric motor (6). 6. 6. The power tool (2) according to any one of the above items 1 to 5, further comprising a first temperature sensor (18) spaced apart from the electric motor for detecting temperature. 7. An electric tool (2) as described in claim 6, having a neck portion (22), the electric motor (6) being arranged on a first side of the neck portion (22), and the first temperature sensor (18) being arranged on a second side of the neck portion (22) opposite the electric motor (6). 8. The power tool (2) according to any one of 1 to 7 above, which is designed as a long-neck sander. 9. 9. The power tool (2) according to any one of claims 1 to 8, further comprising a brake device (34) for braking the tool (5) during the start-up mode, the braking action of the brake device being temperature dependent, and the control unit (7) being configured to take into account the temperature dependency of the brake device via adjusting the gradient and / or current intensity. 10. 10. The power tool (2) according to any one of the above items 1 to 9, further comprising an operating device (12), and the activation mode can be established via the operating device. 11. A system (1) comprising the power tool (2) according to any one of 1 to 10 above and a portable device (4) capable of establishing a start-up mode. 12. 1. A method for providing a start-up mode for a power tool (2) including a tool (5) and an electric motor (6) for driving the tool (6), wherein the electric motor (6) passes through a speed ramp (DR) during the start-up mode, and the speed of the electric motor (6) is continuously increased along the speed ramp (DR) to an operating speed (ADZ); detecting a temperature; for the start-up mode, adjusting the gradient of the rotation speed ramp (DR) based on the detected temperature and / or adjusting the current intensity of the motor current (MI) based on the detected temperature; providing a start-up mode with an adjusted slope of the rotation speed ramp (DR) and / or an adjusted current intensity of the motor current (MI). 13. 13. The method of claim 12, further comprising adjusting the slope of the rotation speed ramp (DR) to a relatively large value when the detected temperature is relatively high, and adjusting the slope of the rotation speed ramp to a relatively small value when the detected temperature is relatively low. 14. 14. The method of claim 12 or 13, further comprising the step of adjusting the motor current (MI) with a relatively small current intensity when the detected temperature is relatively high, and adjusting the motor current (MI) with a relatively large current intensity when the detected temperature is relatively low. 15. 15. The method according to any one of claims 12 to 14, further comprising the steps of switching from the start-up mode to a working mode when the operating speed (ADZ) is reached, and controlling the electric motor (6) in the working mode using a sensorless principle, in particular using the back EMF principle, to detect a current rotor angle and / or a current rotational speed of the electric motor (6). 16. 16. The method according to any one of claims 12 to 15, comprising the step of controlling the electric motor (6) in the start-up mode without detecting or taking into account a rotor angle of the electric motor (6) and / or a rotation speed of the electric motor (6). 17. 17. The method according to any one of claims 12 to 16, wherein the temperature is detected by a first temperature sensor (18) spaced apart from the electric motor. 18. 18. The method according to claim 17, wherein the power tool (2) has a neck portion (22), the electric motor (6) is disposed on a first side of the neck portion (22), and the first temperature sensor (18) is disposed on a second side of the neck portion (22) opposite the electric motor (6). 19. 19. The method according to any one of claims 12 to 18, wherein the power tool (2) is designed as a long-neck sander. 20. 20. The method according to any one of claims 12 to 19, further comprising the step of braking the tool (5) during the start-up mode by means of a braking device (34), the braking action of which is temperature dependent, and taking into account the temperature dependency of the braking device (34) via adjusting the gradient and / or the current intensity. 21. 21. The method according to any one of claims 12 to 20, further comprising the step of establishing the startup mode via an operating device (12). 22. 22. The method according to any one of claims 12 to 21, further comprising the step of establishing said activation mode via a mobile device (4). 23. 1. An assembly comprising: an electric motor (6) for driving a tool (5); and a control unit (7) for controlling the electric motor (6) by a motor current (MI), the control unit (7) having a start-up mode, in which the control unit (7) controls the electric motor (6) such that the electric motor (6) passes through a speed ramp (DR) during the start-up mode and the speed of the electric motor (6) is continuously increased along the speed ramp up to an operating speed (ADZ), the control unit (7) being configured to adjust the slope of the speed ramp (DR) for the start-up mode based on a detected temperature and / or adjust the magnitude of the motor current (MI) for the start-up mode based on the detected temperature. 24. 13. A computer program product comprising instructions for causing the power tool (2) described in claim 1 to perform the method steps described in claim 12. 25. 25. A computer-readable medium having stored thereon the computer program described in 24 above. 26. 25. A method comprising the step of playing on a power tool (2) a computer program product as set forth in claim 24.

Claims

1. A power tool (2) including a tool (5), an electric motor (6) for driving the tool (5), a control unit (7) for controlling the electric motor (6) by a motor current (MI), and a first temperature sensor (18) for detecting a temperature, the control unit (7) has a start-up mode, in which the control unit (7) controls the electric motor (6) so that during the start-up mode the electric motor (6) passes through a speed ramp (DR) and the speed of the electric motor (6) is continuously increased along the speed ramp (DR) up to an operating speed (ADZ), the control unit (7) being configured to adjust the slope of the speed ramp (DR) for the start-up mode based on a temperature detected by a first temperature sensor (18) and / or adjust the intensity of the motor current (MI) for the start-up mode based on the detected temperature, The power tool (2) includes a braking device (34) for braking the tool (5) during a start-up mode; The braking action of the brake device is temperature dependent, The power tool, wherein the control unit (7) is configured to take into account the temperature dependence of the braking device through adjustment of the gradient and / or current intensity.

2. 2. The power tool (2) of claim 1, wherein the control unit (7) is configured to adjust the slope of the rotation speed ramp (DR) to be relatively large when the detected temperature is relatively high, and to adjust the slope of the rotation speed ramp (DR) to be relatively small when the detected temperature is relatively low.

3. 3. The power tool (2) according to claim 1 or 2, wherein the control unit (7) is configured to adjust the motor current (MI) with a relatively small current intensity when the detected temperature is relatively high, and to adjust the motor current (MI) with a relatively large current intensity when the detected temperature is relatively low.

4. 4. The power tool (2) according to claim 1, wherein the control unit (7) is configured to switch from a start-up mode to a work mode when an operating speed (ADZ) is reached, and to perform control of the electric motor (6) in the work mode using a sensorless principle to detect a current rotor angle and / or a current rotational speed of the electric motor (6).

5. The power tool (2) according to any one of claims 1 to 4, wherein the control unit (7) is configured to control the electric motor (6) in a start-up mode without detecting or taking into account the rotor angle of the electric motor (6) and / or the rotation speed of the electric motor (6).

6. An electric tool (2) as described in any one of claims 1 to 5, wherein the first temperature sensor (18) is spaced apart from the electric motor (6).

7. 7. The power tool (2) of claim 6, having a neck portion (22), the electric motor (6) being disposed on a first side of the neck portion (22), and the first temperature sensor (18) being disposed on a second side of the neck portion (22) opposite the electric motor (6).

8. The power tool (2) according to any one of claims 1 to 7, which is designed as a long-neck sander.

9. The power tool (2) according to any one of claims 1 to 8, further comprising an operating device (12) via which the activation mode can be configured.

10. A system (1) comprising a power tool (2) according to any one of claims 1 to 9 and a mobile device (4) capable of configuring activation modes.

11. 1. A method for providing a start-up mode for a power tool (2) including a tool (5), an electric motor (6) for driving the tool (6), and a first temperature sensor (18) for detecting a temperature, the method comprising: the electric motor (6) passes through a speed ramp (DR) during a start-up mode, along which the speed of the electric motor (6) is successively increased up to an operating speed (ADZ); - detecting the temperature by a first temperature sensor (18); - for the start-up mode, adjusting the slope of the rotation speed ramp (DR) based on the detected temperature and / or adjusting the current intensity of the motor current (MI) based on the detected temperature; - providing a start-up mode with an adjusted gradient of the rotation speed ramp (DR) and / or an adjusted current intensity of the motor current (MI), The method further comprises the steps of braking the tool (5) during a start-up mode by means of a braking device (34), the braking action of which is temperature dependent, and taking into account the temperature dependency of the braking device (34) through adjustment of the gradient and / or current strength.

12. 12. The method of claim 11, further comprising adjusting the slope of the rotation speed ramp (DR) to a relatively large value when the detected temperature is relatively high, and adjusting the slope of the rotation speed ramp to a relatively small value when the detected temperature is relatively low.

13. 13. The method according to claim 11 or 12, further comprising the step of adjusting the motor current (MI) with a relatively small current intensity when the detected temperature is relatively high, and adjusting the motor current (MI) with a relatively large current intensity when the detected temperature is relatively low.

14. A method according to any one of claims 11 to 13, further comprising the steps of switching from a start-up mode to a working mode when an operating speed (ADZ) is reached, and performing control of the electric motor (6) in the working mode using a sensorless principle to detect the current rotor angle and / or current speed of the electric motor (6).

15. 15. The method according to claim 11, comprising controlling the electric motor (6) in a start-up mode without detecting or taking into account the rotor angle of the electric motor (6) and / or the rotational speed of the electric motor (6).

16. A method according to any one of claims 11 to 15, wherein the first temperature sensor (18) is spaced apart from the electric motor (6).

17. 17. The method according to claim 16, wherein the power tool (2) has a neck portion (22), the electric motor (6) is disposed on a first side of the neck portion (22), and the first temperature sensor (18) is disposed on a second side of the neck portion (22) opposite the electric motor (6).

18. The method according to any one of claims 11 to 17, wherein the power tool (2) is designed as a long-neck sander.

19. A method according to any one of claims 11 to 18, further comprising the step of establishing the start-up mode via an operating device (12).

20. A method according to any one of claims 11 to 19, further comprising the step of establishing the startup mode via the mobile device (4).

21. An assembly of a power tool (2) comprising an electric motor (6) for driving the tool (5), a control unit (7) for controlling the electric motor (6) by a motor current (MI), and a first temperature sensor (18) for detecting a temperature, the control unit (7) has a start-up mode, in which the control unit (7) controls the electric motor (6) so that the electric motor (6) passes through a rotation speed ramp (DR) during the start-up mode and the rotation speed of the electric motor (6) is continuously increased along the rotation speed ramp up to an operating rotation speed (ADZ); the control unit (7) is configured to adjust the gradient of the rotation speed ramp (DR) for a start-up mode based on the temperature detected by the first temperature sensor (18) and / or to adjust the intensity of the motor current (MI) for a start-up mode based on the detected temperature, The assembly includes a brake device (34) for braking the tool (5) during a start-up mode, the braking action of the brake device being temperature dependent, and the control unit (7) being configured to take into account the temperature dependency of the brake device through adjustment of the gradient and / or current strength.

22. A computer program product comprising instructions for causing a power tool (2) according to claim 1 to perform the method steps according to claim 11.

23. 23. A computer readable medium having stored thereon the computer program of claim 22.

24. A method comprising the step of reproducing the computer program product of claim 22 on a power tool (2).

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