Method for operating a hand-held power tool
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-12-08
- Publication Date
- 2026-07-02
Smart Images
Figure EP2025085870_02072026_PF_FP_ABST
Abstract
Description
[0001] R. 417293
[0002] - 1 -
[0003] Description
[0004] title
[0005] Method for operating a hand-held power tool
[0006] State of the art
[0007] Document EP3023198 A1 describes a hand-held machine tool whose operation can be controlled by axial and / or rotary movements. These movements can be directed towards or away from the workpiece. Additionally, on / off functions, direction of rotation (e.g., clockwise or counterclockwise), speed, and torque can be set.
[0008] Document EP4406700 A1 describes a method for operating a hand-held machine tool for screwing fasteners into a substrate. The tool holder, and thus the fastener, is first rotated in one direction. The tool holder is then rotated in the opposite direction at a defined speed and for a defined duration.
[0009] EP3003649 A1 describes a hand-held machine tool with a gearbox of at least two stages, enabling easy, comfortable and safe gear changes.
[0010] Patent DE102015211 689 A1 describes a hand-held machine tool with a multi-stage gearbox. An actuator enables, for example, gear changes or the activation and deactivation of a percussion mechanism without requiring any force from the user. The user simply operates a switch that controls the actuator, thus engaging the desired gear or activating the percussion mechanism. R. 417293
[0011] - 2 -
[0012] It is also widely known that machine tools use motor current to shut down a screw connection to tighten it using a predetermined torque.
[0013] Disclosure of the invention
[0014] In contrast, the inventive method with the features of claim 1 has the advantage that fastening or loosening a fastening element is carried out conveniently and at high speed.
[0015] The process includes the following steps:
[0016] • Driving a tool holder with a mounting direction of rotation with a first drive direction of rotation of the drive shaft in a first operating state
[0017] • Driving the tool holder in the mounting direction with a second drive direction of the drive shaft, which is opposite to the first drive direction of the drive shaft, in a second operating state. In particular, the tool holder accommodates a tool changing device, which in particular indirectly drives a fastening element. The fastening element is a mechanical part used to connect or fix two or more components together, for example, a screw, a nut, a threaded bolt, or the like.
[0018] The actuation of the tool holder describes, in particular, a process in which the fastening element is moved in a specific direction by a rotary motion of the tool changing device or the tool itself, either to fasten or loosen it. This rotary motion can be generated by an electric, pneumatic, or mechanical drive system. The specific direction is the fastening rotation direction.
[0019] The fastening rotation direction is, in particular, a specific direction of rotation in which the tool holder, and especially the tool changing device, rotates the fastening element to fasten or loosen it. Fastening rotation direction 417293
[0020] - 3 -
[0021] The direction of rotation can be, in particular, a clockwise rotation in the case of a right-hand thread. The direction of rotation for tightening can also include, in particular, loosening the fastener. The direction of rotation for tightening is, in particular, constant during a screwing operation.
[0022] The direction of rotation of the fastening may in particular coincide with the first direction of rotation of the drive shaft or the second direction of rotation of the drive shaft (hereinafter referred to as "direction of rotation").
[0023] The first operating state describes, in particular, the operating mode in which the tool holder is driven in a defined fastening direction with the first drive direction. This state is especially optimized for the rapid fastening of the fastener. This state is especially optimized for the rapid rotation of the tool holder. The first operating state is, in particular, a high-speed mode.
[0024] The second operating state describes, in particular, the mode in which the tool holder is driven in the fastening direction by a second drive direction that is opposite to the first drive direction. This second operating state is specifically optimized for loosening the fastener with a higher torque compared to the first operating state. This configuration allows the user to fasten or loosen the fastener securely and efficiently. The second operating state is, in essence, a high-torque mode.
[0025] The first operating condition is, in particular, one in which the tool holder has a higher rotational speed. The second operating condition is, in particular, one in which the tool holder has a higher clamping torque.
[0026] In other words, the drive unit rotates, in particular in different drive directions, while the tool holder retains the same mounting direction. Specifically, an output unit has an eccentric device configured to impart a rotary motion to a tool holder. 417293
[0027] - 4 -
[0028] The eccentric shaft is converted into an oscillating or reciprocating motion, which is transmitted to the tool holder, in particular by means of a pawl device. Furthermore, the output unit has a direction-of-rotation lever, which is specifically designed to act on the pawl device, so that the tool holder operates in one direction and can rotate freely in the opposite direction.
[0029] The hand-held power tool is designed in particular as an electrically driven ratchet, comprising a tool holder for receiving a tool, wherein the tool is arranged to drive the fastening element rotationally; further comprising a drive unit with a drive shaft and a control unit.
[0030] Preferably, the switch from the first operating state to the second operating state occurs automatically. This means that the machine ideally switches between the two operating states independently and without manual intervention from the user. Advantageously, the user does not have to manually switch between modes; the machine automatically selects the optimal time for the change, and the risk of incorrect operation is minimized.
[0031] Preferably, the procedure includes the following further steps:
[0032] • Capture at least one parameter of the fastening element
[0033] • Automatic switching depending on at least one parameter of the fastening element.
[0034] The captured parameter can be, for example, a dimension, thread length, thread pitch, or the like. Dimensions can be captured using sensors, an input form, a database query based on a fastener identifier, or a combination of these methods. The captured information can, in particular, influence the automatic switching between operating states, for example, by adjusting switching thresholds or time intervals. This advantageously allows for adaptation to the specific requirements of the fastener. 417293
[0035] - 5 -
[0036] gungselements and increases efficiency and user comfort during a screwing process.
[0037] In another preferred embodiment, the hand-held power tool has a sensor unit and records the time course of a sensor signal. The sensor signal can, for example, relate to motor current, torque, vibrations, sound, or the position or angle of rotation of the fastener. In particular, an analysis of the time course enables a dynamic adjustment of the operating state. For example, the machine can adjust the speed or torque, switch off automatically, or detect errors in the screwdriving process.
[0038] Preferably, the sensor signal relates to the motor temperature. In this preferred embodiment, the sensor unit records the motor temperature over time and, in particular, enables the determination of the motor's operating condition. The acquired data can be used, for example, to implement overload protection, optimize the power of the power tool, initiate predictive maintenance, and adapt the operating state to the ambient temperature. The power tool can reduce its power output or shut down, especially at high motor temperatures. This can prevent overheating.
[0039] Preferably, the sensor signal relates to a motor current. In this embodiment, the sensor unit specifically detects the time course of the motor current. This enables, in particular, indirect measurement of the torque, detection of the motor's load state, control of the switching between operating states, fault detection, and / or control of the speed or torque. For example, the power tool can automatically switch to the second operating state, especially the high-torque mode, in the event of a rapidly increasing motor current, or report a fault in the event of an unusual current pattern.
[0040] The following further steps are preferably carried out:
[0041] Determining whether a motor current threshold has been reached or exceeded. R. 417293
[0042] - 6 -
[0043] Automatic switching from the first operating state to the second operating state depending on whether the motor current threshold is reached or exceeded.
[0044] Controlling the drive unit in the second operating state.
[0045] The motor current threshold is specifically chosen to ensure that the switchover occurs at an optimal time, for example, when the fastener begins to tighten. Controlling the drive unit in the second operating state can include adjusting the speed, torque, or other parameters.
[0046] The following further steps are preferably carried out:
[0047] Determining whether the motor current threshold is reached or fallen below in the second operating state
[0048] Automatic switching from the second operating state to the first operating state depending on whether a reset motor current threshold is reached or fallen below.
[0049] Controlling the hand-held power tool in its first operating state.
[0050] The reset motor current threshold is, in particular, lower than the motor current threshold for switching from the first operating state to the second operating state. The reset motor current threshold is specifically chosen to ensure that switching back occurs at the optimal time, for example, when the fastener has been loosened with high torque and is being unscrewed at high rotational speed.
[0051] Preferably, the automatic switching occurs only after a time constant of at least 100 ms, preferably 300 ms, and most preferably 500 ms, has elapsed. This means that the handheld power tool does not switch immediately, even if, for example, the reset motor current threshold is briefly reached or fallen below, but only when the threshold remains reached or below the threshold after the time constant has elapsed. This particularly increases the stability of the system and prevents unnecessary switching back and forth, which leads to increased wear and a reduced service life of the handheld power tool. R. 417293
[0052] - 7 -
[0053] The machine is running. The time constant can be fixed or variable.
[0054] The following further steps are preferably carried out:
[0055] • Determining whether a further motor current threshold has been reached or exceeded, in particular a maximum motor current,
[0056] • Switching off the drive unit depending on whether the further motor current threshold is reached or exceeded.
[0057] To prevent overloading and damage to the drive unit, the method preferably detects when a further motor current threshold has been reached or exceeded, in particular a maximum permissible motor current. This further motor current threshold is, in particular, higher than the motor current threshold for switching between operating states. This further motor current threshold serves, in particular, as a safety shutdown. This further motor current threshold also serves, in particular, as indirect torque monitoring. The shutdown can be, in particular, reversible or irreversible. For example, the shutdown can be a software-controlled shutdown or the tripping of a fuse.
[0058] The drive unit is switched off, particularly via software control by the control unit, and this shutdown is reversible. In particular, after the overload has been removed, the hand-held power tool can be restarted, for example, by activating the latching mechanism.
[0059] In particular, a time delay of, for example, 100 milliseconds can be implemented for the automatic switchover from the first operating state to the second operating state to ignore short-term power spikes. Specifically, ignoring these power spikes can prevent unintentional shutdowns.
[0060] In particular, the user may be informed of the shutdown by a signal, which may be visual, acoustic, or optical. The maximum permissible motor current is determined primarily based on the motor's thermal capacity and the application requirements. R. 417293
[0061] - 8 -
[0062] Preferably, the first operating state has a higher fastening speed of the fastening element compared to the second operating state.
[0063] Preferably, the second operating state has a higher fastening torque of the fastening element compared to the second operating state.
[0064] The first operating state is characterized by a higher fastening speed of the fastener compared to the second operating state. This allows, in particular, for quick tightening or loosening of the fastener. The second operating state, on the other hand, features a higher fastening torque of the fastener compared to the first operating state. This enables powerful tightening or loosening of the fastener. By switching between these two operating states, the screwing process can be optimized and adapted to the respective requirements.
[0065] The invention further comprises a hand-held power tool, in particular an electrically driven ratchet, comprising a drive unit, a control unit and a tool holder, wherein the hand-held power tool can perform a method according to one of the previously described embodiments.
[0066] Preferably, the hand-held power tool comprises an eccentric unit for generating an oscillating motion, a ratchet mechanism (52) which can be driven by means of the oscillating motion, and a device for changing a transmission ratio between the drive unit (30) and the ratchet mechanism (52).
[0067] Brief description of the characters
[0068] Fig. 1 shows a preferred embodiment of an electrically driven ratchet in a side view,
[0069] Fig. 2 shows a sectional view of the preferred embodiment of the electrically driven ratchet according to Fig. 1, R. 417293
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[0071] Fig. 3 shows a section of a ratchet handle housing in a top view,
[0072] Fig. 4 shows a section of a ratchet in a sectional view,
[0073] Fig. 5 shows a flowchart of a preferred embodiment of the method,
[0074] Fig. 6 shows a graph of motor current over time for a screwing operation.
[0075] Fig. 7 shows a graph of motor current over time for a screwing operation on a dirty thread, and
[0076] Fig. 8 shows a graph of motor current over time for the release of a fastener.
[0077] Identical elements or elements with the same function are marked with the same reference symbols in the figures.
[0078] Figure 1 shows a preferred embodiment of an electrically driven ratchet 1 (hereinafter referred to as "ratchet") in a side view.
[0079] The ratchet 1 is a mechanical device used to tighten or loosen a fastener 213, such as screws or nuts. Unlike conventional ratchets, the driven ratchet 1 has features that improve its functionality and efficiency. In the preferred embodiment shown in Figure 1, the ratchet 1 is electrically driven by a drive unit 30 and includes a battery pack 6. The drive unit 30 (Figure 2) generates the torque required for tightening or loosening fasteners 213.
[0080] A handle housing 4 of the ratchet 1 serves in particular to form a handle of the ratchet 1. The handle housing 4 is designed so that it can be gripped by a user with one hand. The handle housing 4 enables the user to
[0081] - 10 -
[0082] The ratchet is designed to be securely gripped and operated, ensuring ergonomic and comfortable handling.
[0083] The handle housing 4 has an operating side 104 which includes an actuating device 80 in the form of a pawl 83. The pawl 83 enables the user to activate and control the ratchet 1. The operating side 104 is designed in such a way as to allow intuitive and user-friendly operation by means of the large pawl 83, which is easily accessible and simple to operate.
[0084] The handle housing 4 includes, in particular, a lock-off button 43, which forms a safety mechanism for an electrical switch 81 (shown in Fig. 2). The electrical switch 81 can be actuated by means of the pawl 83, the pawl 83 being rotatably mounted in a pivot point 84. The pivot point 84 of the pawl 83 can, for example, be a sliding bearing (not shown) in the handle housing 4.
[0085] The ratchet 1 has a work light 44, which is arranged at a first end 401 of the ratchet 1, on a side facing the tool holder 21. The work light 44 is, in particular, an integrated light source and is suitable for illuminating the working area of the ratchet 1. In the embodiment shown, the work light 44 is designed as an LED lamp, which is activated when the pawl 83 is actuated. In a further embodiment, the work light 44 can be equipped with a switch to turn the light on and off as needed. A user can, for example, operate the ratchet more safely and precisely, especially in poorly lit environments.
[0086] A battery pack receptacle 5 is arranged in a region of a second end 402 of the ratchet 1. The battery pack receptacle 5 is a device or opening that serves to detachably receive and secure a battery pack 6 in order to supply the ratchet 1 with electrical energy. This battery pack receptacle 5 has a mechanical and electrical interface for connecting the battery pack 6 electrically and mechanically to the ratchet 1. R. 417293
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[0088] A charge level indicator 42 is arranged in the region of the second end 402 of the handle housing 4. In particular, the charge level indicator 42 is arranged on one side 105 of the handle. The charge level indicator shows the user the current charge level of the battery pack 6. The charge level indicator 42 can be designed in various ways, such as using LEDs, LCD displays, or digital displays. In the illustrated preferred embodiment, the charge level indicator 42 is implemented using several LEDs. The charge level indicator 42 can also display the remaining charge level in the form of bars or percentages. Furthermore, different colors can be used for the charge level indicator 42 to indicate the charge level of the battery pack 6. For example, green for a full battery, yellow for a medium charge level, and red for a low charge level.
[0089] In the embodiment shown, the handle housing 4 and the battery pack receptacle 5 are made in one piece.
[0090] Furthermore, the handle housing accommodates four electronic components 8. These electronic components 8 include, for example, an electrical switch 81, a printed circuit board 82, and a plurality of electrical conductors 85 for conducting electrical current and / or signals. A battery pack 6 and the printed circuit board 82 are arranged overlapping each other. This allows for a particularly compact design. The overlap is more than 38%. In particular, an actuating axis 810 of the switch 81 intersects the printed circuit board 82. The illustrated embodiment includes a sensor unit 86, which can measure, among other things, a motor current 505-507. This enables, for example, automatic shutdown to prevent overload or damage to fastening elements 213.
[0091] The ratchet 1 further comprises a drive housing 3. The drive housing 3 is connected to the handle housing 4 at its first end 401 in an axial direction along the longitudinal axis 100, for example by means of fasteners 48. The drive housing 3 is inserted into the handle housing 4 in the connection area.
[0092] The drive unit 30 shown in Figure 2 is arranged in the drive housing 3, with the drive housing 3 being partially inserted into the handle housing 4,R. 417293
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[0094] The drive unit 30 is also partially arranged in the handle housing. The drive unit 30 is an electric motor 30, which has a drive shaft 32. The drive shaft 32 is supported in the drive housing 3, in particular by means of a bearing 33. The drive shaft 32 defines a longitudinal axis 100 of the ratchet 1. In particular, the ratchet 1 extends along the longitudinal axis 100. The drive housing 3 is detachably connected to the handle housing 4 at a first end 401 in the axial direction of the longitudinal axis 100.
[0095] The ratchet 1 further comprises a gear unit 70, which translates the torque generated by the electric motor 30. The gear unit 70 preferably has a planetary gear set. The gear unit 70 is screwed to the drive housing 3. The gear unit 70 is screwed to the drive housing 3 via an external thread in its encapsulation. The gear unit 70 is screwed to an output unit 2. In addition to translating the torque, the gear unit 70 also performs a connecting function. The gear unit 70 connects the output unit 2 and the drive housing 3 in such a way that the torque generated by the electric motor 30 can be transmitted to the output unit 2.
[0096] The output unit 2 comprises, in particular, an output housing 24, which accommodates an eccentric device 22 and at least parts of the tool holder 21, along with a direction-of-rotation lever 23. The eccentric device 22 is configured to convert a rotary motion of the drive shaft 32 into an oscillating or reciprocating motion, which is transmitted to the tool holder 21, in particular by means of a pawl device 52 (shown in Fig. 4). The direction-of-rotation lever 23 is configured to act on the pawl device so that the tool holder 21 operates in one direction of rotation for fastening and can rotate freely in the opposite direction. The tool holder 21 is configured to accommodate a tool 212 on a tool-changing device 210. The tool 212 can, for example, be a socket wrench for tightening or loosening screws or nuts.Furthermore, extensions, adapters, joints and / or bit attachments can be mounted on the tool holder 21. The tool holder 21 has a square drive on its outer surface, for example in a size of 1 / 4 inch, 3 / 8 inch or 1 / 2 inch. R. 417293.
[0097] - 13 -
[0098] The grip area 60 is specifically designed to offer the user improved haptics and handling. For example, the grip area can be made of thermoplastic elastomer (TPE), which provides a soft and grippy surface, while the casing area 48 is made of a different material such as plastic, for example ABS, or metal to ensure the structural integrity of the housing 4. The TPE storage device 10 (see also Fig. 3) can provide an anti-slip property or prevent the ratchet 1 from rolling away.
[0099] Figure 3 shows a section of a handle housing 4. Also shown is the storage device 10, which is located on the side of the ratchet 1 facing away from the tool holder 21, or rather, on the handle side 105. The handle side 105 of the ratchet 1 is the side of the ratchet 1 that, viewed from a perpendicular angle to a drive shaft 32 (Fig. 2), is parallel to and opposite to the mounting direction 211 of a tool 212. In other words, the handle side 105 is the side facing away from a tool holder 21. The storage device 10 has a bridge 93 which connects two hump-like support points. In a parked position, the support points on the handle side 105 of the ratchet 1 make contact with a workbench.
[0100] Figure 4 shows a section of the output unit 2. The drive shaft 32 is rotatably mounted about a pivot axis 320. In the section shown, the drive shaft 32 is supported by two needle bearings 50 (for illustrative purposes, only one needle bearing 50 is shown). The needle bearings 50 are axially supported by a collar 322, which is integrally formed with the drive shaft 32. A first stop surface 323 and a second stop surface 324 (not shown) extend directly from an end face of the collar 322 at right angles to the end face of the collar 322. The stop surfaces 323, 324 can, for example, be machined from the drive shaft 32 by a machining process. The stop surfaces 323, 324 are integrally formed with the collar 322. The stop surfaces 323, 324 are integrally formed with the drive shaft 32.
[0101] The eccentric unit 22 is partially inserted into the drive shaft 32 and rotatably mounted. The rotational movement of the eccentric unit 22 relative to the drive shaft 32 is R. 417293
[0102] - 14 -
[0103] The drive shaft 32 is limited by the stop cam 221, which interacts with the stop surfaces 323 and 324 on the drive shaft 32. The stop cam 221 has a first cam stop surface 230 and a second cam stop surface 231 (not shown). In Figure 3, the second cam stop surface 231 rests against the second stop surface 324 (Figure 4). When the drive shaft 32 rotates counterclockwise, the contact between the stop surfaces 324 and 231 creates a positive connection between the drive shaft 32 and the eccentric unit 22. When rotating clockwise, the first stop surface 323 rests against the first cam stop surface 230. The eccentric unit 22 can thus be switched between two defined rotational positions.These rotational positions define two different eccentricities between the eccentric pin axis (not shown) and the rotational axis 320 of the drive shaft, thereby realizing different gear ratios between the drive shaft 32 and the ratchet mechanism 52.
[0104] Figure 5 shows a method in a preferred embodiment. In a first step S1, the ratchet 1, or the drive unit 30, is activated by actuating the pawl 83.
[0105] In a further step, S2, a motor current threshold is read in. This can be a factory-defined value or a value read in via a human-machine interface or a wirelessly connected device. The motor current threshold can be adjusted, for example, based on the experience of a user who performs recurring fastening operations. Alternatively or additionally, the user could have the option of setting the time constant 53 for the second operating state 520 via the human-machine interface.
[0106] In the following step S3, a continuous determination of the motor current 505-507 is initially carried out using a sensor unit 86.
[0107] After activation, ratchet 1 is initially set to the first operating state 510 (step S4). Alternatively or additionally, setting it to the first operating state 510 can be performed in one step after switching on ratchet 1. Ratchet 1 can be returned to the first operating state during operation. R. 417293
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[0109] The position 510 can be shifted (step S4), for example, after loosening a screw in the second operating state. If no high torque is required to loosen the screw, faster unscrewing or turning of the screw or nut can be enabled in the first operating state.
[0110] In the following step S5, the ratchet 1 is now operated in the first operating state 510.
[0111] In the following step S6, whether a motor current 505-507 has been reached or exceeded is determined. If this is determined (step S6), the ratchet 1 is switched to the second operating state 520 (step S7), which provides a higher torque through a second gear ratio. The tool holder 21 is now driven in the second operating state 520 with the mounting direction and the second drive direction of the drive shaft 32. In an optional step 7a, the user can be notified of a change in operating mode by means of an optical, visual, or haptic signal. For example, by changing the color of a work light 44. The ratchet 1 is now operated in the second operating state (step S8). Optionally, in step S9, the ratchet 1 is initially operated in the second operating state 520 until a time constant 53, for example, 500 ms, has elapsed.
[0112] If, in the second operating state 520, a reset motor current threshold value 503 is reached or fallen below (step S10), the ratchet 1 is switched back to the first operating state 510 (step S4). The procedure is then repeated from step S4.
[0113] If this is not the case and the motor current 505-507 does not fall below the reset motor current threshold 503 in the second operating state 520, but rather a further motor threshold 502 is reached or exceeded (step S11), then the ratchet 1 is deactivated in a subsequent step S12.
[0114] Not shown, but optionally implemented, is an error handling system that intervenes at several points in the ratchet 1 process flow to detect and resolve potential problems early on. In particular, a check is performed on Validi-R. 417293
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[0116] This is done after user input following step S2. If the value is outside the specifications, an error message can be displayed. In particular, after step S3, overheating or blockage of the drive unit 30 can be detected by means of the sensor unit 86.
[0117] Figures 6-8 show an exemplary diagram of the motor current, displayed with temporal resolution, along with the first operating state 510 and the second operating state 520. The similarities between the diagrams in Figures 6-8 are explained below.
[0118] The ordinate 50 represents the motor current 505-507 over time, which is plotted on the abscissa 52. The motor current 505-507 is shown here as a smooth average value, which in reality is subject to fluctuations. The further ordinate 51 represents the first operating state 510 and the second operating state 520. The motor current threshold 501, which initiates an automatic switch between the first operating state 510 and the second operating state 520 when reached or exceeded, is a constant value in the illustrated embodiment, which is predefined by the factory setting of the ratchet 1. When the motor current 505-507 reaches, exceeds, or falls below the motor current threshold 501, the ratchet 1 switches from the first operating state 510 to the second operating state 520 or vice versa.
[0119] Figure 6 shows an exemplary motor current profile 505 for tightening a fastener 213. In a region 400, which represents a steep increase in motor current, a screw head (not shown) comes into contact with a retaining element (not shown) to be fastened. After switching to the second operating state 520, all flywheels 221, 32, 322 must be reversed in their direction of rotation. Region 401 shows a drop and a renewed increase in motor current 505, representing a brief interruption of the work progress. Once the second operating state 520 is activated, the ratchet 1 continues to tighten the screw, with plastic and elastic deformations or elongations occurring, until finally another motor threshold 502 is reached and the drive unit R. 417293
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[0121] The motor is deactivated (step S12). The further motor threshold value 502 can represent a cut-off value, which either corresponds to the maximum power of ratchet 1 or alternatively to a predefined, adjustable value. The predefined value can be read in step S2 either from the factory-set value, via a human-machine interface, or via a wirelessly connected device. The predefined value can correspond to a predefined tightening torque.
[0122] Figure 7 shows an exemplary motor current profile 506 for tightening a damaged or contaminated fastener 213, for example, due to corrosion. The tightening of the fastener 213 initially corresponds to the representation shown in Figure 6. However, the increase in motor current in region 403 is caused by the contamination in this case. Here too, the motor current threshold 501 is reached, resulting in a switch (step S7) to the second operating state 520. The ratchet 1 is operated in the second operating state 520 (step S8) until the contaminated area of the fastener 213 is traversed (region 408 in Fig. 7). The torque required to drive the fastener 213 decreases, and consequently, the required motor current 506 also decreases, dropping again in region 405. The ratchet 1 continues to operate in the second operating state S9 for a duration 53.When a reset motor current threshold of 503 is reached, the ratchet 1 switches back to the first operating state 510 (step S4) and continues to operate in the first operating state 510 (step S5). The time duration 53 can prevent or dampen an unintentional switch between the two operating states 510 and 520. During the change between operating states 510 and 520, a change in the drive direction of the flywheels also occurs in a region 406, which is why no work progress is made for a short time, as can be seen from the falling motor current.
[0123] Figure 8 shows an exemplary motor current profile 507 for loosening a fastening element 213. The ratchet 1 is initially operated in the first operating state 510 (step S5). The motor current 507 initially rises steeply in a range 410 until the motor current threshold 501 is reached. Corresponding to the previous descriptions, a switch from the first operating state 510 inR takes place. 417293
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[0125] The second operating state 520 takes place. The drop in motor current in area 411 corresponds to area 401. The ratchet 1 loosens the fastening element 213 with a high torque. Once the screw is loosened, the required torque and thus also the motor current 507 decrease in area 412. In area 413, the motor current has reached the reset motor current threshold 503, but continues to fall below it because the time constant 53 has not yet expired. After the time constant 53 has expired, the system switches back to the first operating state 510 (step S4). In an alternative embodiment, the "waiting" for the time constant 53 can be skipped, for example, when loosening the fastening element 213. Area 414 corresponds to area 406. In the first operating state 510, the fastening element 213 is loosened.
[0126] When loosening the screw, ratchet 1 initially starts in HS mode (High Speed), during which the motor current rises sharply and quickly reaches the target value, at which point ratchet 1 switches to HT (High Torque). Ratchet 1 then loosens the screw with high torque. Once the screw is loosened, the required torque and therefore the current decrease. When the reset motor current threshold of 503 for HS mode is reached, ratchet 1 switches to this mode and quickly loosens the screw.
Claims
1. R. 417293 - 19 - Claims 1. Method for operating a hand-held power tool, in particular an electrically driven ratchet, with a tool holder (21) for receiving a tool changing device (210) and a drive unit (30) which is configured to indirectly drive the tool holder (21) rotationally, a drive shaft (32) and a control unit (87), the method comprising the steps: Driving (S5) the tool holder (21) with a fastening rotation direction and a first drive rotation direction of the drive shaft (32) in a first operating state (510); Driving (S8) the tool holder (21) with the fastening direction of rotation with a second drive direction of rotation of the drive shaft (32), which is opposite to the direction of rotation of the first drive direction of rotation of the drive shaft (32), in a second operating state (520).
2. The method according to claim 1, characterized by the following further step: Automatic switching (S7) from the first operating state (510) to the second operating state (520).
3. The method according to claim 2, characterized by the following further steps: Detect at least one parameter of a fastening element (213) and automatically switch from the first operating state (510) to the second operating state (520) depending on the detected embodiment of the fastening element (213).
4. Method according to one of the preceding claims, characterized by a sensor unit (86) of the hand-held power tool (1) and by the following further step: R. 417293 - 20 - Acquisition (S3) of a temporal progression of a sensor signal of the sensor unit (86).
5. Method according to claim 4, characterized in that the sensor signal relates to a motor temperature.
6. Method according to claim 4 or 5, characterized in that the sensor signal relates to a motor current (505, 506, 507).
7. The method of claim 6, characterized by the following further steps: Determining (S6) whether a motor current threshold has been reached or exceeded (501) Automatic switching (S7) from the first operating state (510) to the second operating state (520) depending on reaching or exceeding the motor current threshold (501). Driving (S8) the tool holder (21) with the first fastening rotation direction with a second drive rotation direction of the drive shaft (32) in the second operating state (520).
8. Method according to claim 6 or 7, characterized by the following further step: Determining (S10) whether a reset motor current threshold value (503) has been reached or fallen below in the second operating state (520), Automatic switching (S4) from the second operating state (520) to the first operating state (510) depending on reaching or falling below a reset motor current threshold (503), Driving (S5) the tool holder (21) with the fastening rotation direction with the first drive rotation direction of the drive shaft (32) in the first operating state (510).
9. Method according to claim 7 or 8, characterized in that the automatic switching only takes place after the elapse (S9) of a time constant (53) of at least 100 ms, preferably 300 ms, particularly preferably 500 ms. R. 417293 - 21 - 10. The method of claim 9, characterized by the following further step: Determining (S11) whether a further motor current threshold has been reached or exceeded, in particular a maximum motor current, Switching off (S12) of the drive unit (30) depending on reaching or exceeding the further motor current threshold (502).
11. Method according to one of the preceding claims, characterized in that the first operating state (510) has a higher fastening speed of the tool holder (21) compared to the second operating state (520).
12. Method according to one of the preceding claims, characterized in that the second operating state (520) has a greater fastening torque of the tool holder (21) compared to the first operating state (510).
13. Hand-held power tool (1), in particular an electrically driven ratchet, comprising a drive unit (30), a control unit (87), a tool holder (21), characterized in that the hand-held power tool performs a method according to one of claims 1-12.
14. Hand-held power tool according to claim 13, characterized by an eccentric unit (22) for generating an oscillating motion, a ratchet mechanism (52) which can be driven by means of the oscillating motion, and a device for changing a transmission between the drive unit (30) and the ratchet mechanism (52).