Control unit for a drive unit of a hand-held machine tool, drive unit, hand-held machine tool and method for operating a hand-held machine tool

Abstract

The invention relates to a control unit (24) for a drive unit of a hand-held machine tool. This comprises a target speed specification device (34) with an actual voltage input interface (36) for receiving an actual voltage value (USE) of an electrical energy storage unit (32) and a limit voltage input interface (38) for receiving a limit voltage value (UG). The target speed specification device (34) is coupled via signals to a target speed input interface (50) of a speed control device (44). The target speed specification device (34) is designed to provide the variable target speed (NS) at the target speed input interface (50) based on the actual voltage value (USE) and the limit voltage value (UG). The invention also relates to a drive unit for a hand-held machine tool having a control unit (24) of this type. The invention also relates to a hand-held machine tool with a drive unit of this type. The invention further relates to a method for operating a hand-held machine tool.

Description

[0001] Control unit for a drive unit of a hand-held power tool, drive unit, hand-held power tool and method for operating a hand-held power tool

[0002] The invention is directed to a control unit for a drive unit of a handheld power tool having a speed control device. The speed control device comprises an actual speed input interface for receiving an actual speed of the handheld power tool, a target speed input interface for receiving a target speed of the handheld power tool, and an output interface for outputting a target operating parameter for the handheld power tool to be controlled.

[0003] The invention also relates to a drive unit for a hand-held power tool, comprising such a control unit.

[0004] Furthermore, the invention is directed to a hand-held power tool with such a drive unit.

[0005] The invention also relates to a method for operating a hand-held power tool.

[0006] Hand-held power tools with speed control via a speed control device are well known in the art. Hand-held power tools are often powered by a battery or accumulator.

[0007] This means that the energy that can be provided by the battery or accumulator is finite. In contrast, however, it is desirable for the user of the hand-held power tool to have as few restrictions on energy supply as possible. A long battery or accumulator runtime is particularly advantageous for the user. This means that the user has to worry about charging or replacing the battery or accumulator relatively rarely. The battery or accumulator runtime depends heavily on the type and intensity of use of the hand-held power tool. The user must therefore generally pay attention to the charge level of the battery or accumulator themselves. The user must keep an eye on the charge level, especially in situations where there is no or only limited charging or changing option for the battery.This allows the user to adjust the type and intensity of use of the handheld power tool, if necessary, to extend the battery life or accumulator life sufficiently to allow the user to complete the intended tasks using the handheld power tool. This does not necessarily result in optimal utilization of the battery's energy content.

[0008] It is therefore the object of the present invention to provide a hand-held power tool which has a long battery life or accumulator life without any separate action by the user.

[0009] The problem is solved by means of a control unit for a drive unit of a hand-held power tool. The control unit comprises a speed control device. The speed control device has an actual speed input interface for receiving an actual speed of the hand-held power tool, a target speed input interface for receiving a target speed of the hand-held power tool, and an output interface for outputting a target operating parameter for the hand-held power tool to be controlled. Furthermore, the control unit comprises a target speed specification device for specifying a variable target speed for the hand-held power tool at the target speed input interface.The target speed setting device comprises an actual voltage input interface for receiving an actual voltage value of an electrical energy storage unit for the handheld power tool and a limit voltage input interface for receiving a limit voltage value. The target speed setting device is signal-coupled to the target speed input interface of the speed control device. Furthermore, the target speed setting device is designed to provide the variable target speed at the target speed input interface based on the actual voltage value and the limit voltage value. In this context, the speed control device is designed to provide the target operating parameter as a function of the actual speed and the target speed in such a way that the actual speed adapts to the target speed.The target operating parameter is in particular a target current or a target voltage by means of which the drive unit of the hand-held power tool, in particular a drive motor unit of the hand-held power tool, is controlled. In the simplest case, the drive motor unit is a drive motor. The actual speed can be provided by means of a speed detection unit. The speed detection unit can comprise a speed sensor. Alternatively, the speed detection unit comprises a field model so that the actual speed can be provided without using a speed sensor. The actual speed relates to a speed of a tool or a tool holder of the hand-held power tool. Unlike in the prior art, the target speed is not specified directly by the user, but is determined and provided as a variable target speed by the target speed specification device.This occurs depending on the actual voltage value and the limit voltage value. The target speed, or more precisely the variable target speed, which is determined and provided by the target speed specification device, is therefore not necessarily identical to a speed specified by a user. The actual voltage value at least indirectly describes a state of charge of the electrical energy storage unit. The limit voltage value is fixed. In other words, the target speed is specified depending on the state of charge of the electrical energy storage unit. In particular, in this context, the target speed can be reduced if a comparatively low state of charge of the electrical energy storage unit is determined using the actual voltage value. As a result, the power drawn from the electrical energy storage unit is also reduced.In this context, the current provided by the electrical energy storage unit decreases. As a result, the voltage drop across the internal electrical resistance of the energy storage unit decreases. Furthermore, the voltage drop across the internal resistance of the energy storage unit, i.e., across the energy storage unit, decreases. This means that an existing electrical energy storage unit can be used for longer. If the handheld power tool is switched off as soon as the actual voltage value falls below a predetermined threshold, such a switch-off occurs correspondingly later. The accumulator or battery life thus increases. No action by the user is required.

[0010] The present invention therefore relates to the specification of a variable target speed for the hand-held machine tool at the target speed input interface of the

[0011] Speed ​​control device by means of the target speed specification device. The fact that the target speed is variable means that the target speed can assume different values ​​at different times. In particular, the variable target speed is always changed continuously, i.e. without any significant jumps in the target speed that are noticeable to the user. The target speed can therefore be variably specified by the target speed specification device depending on the state of charge of the electrical energy storage unit, i.e. the specified variable target speed changes, in particular continuously, with the state of charge of the electrical energy storage unit. The specified variable target speed can be continuously reduced if a comparatively low state of charge of the electrical energy storage unit is determined using the actual voltage value.

[0012] Optionally, it can also be provided that the hand-held power tool is switched off when a switch-off criterion is met. Once the hand-held power tool has been switched off, it can no longer be used. Such a switch-off criterion relates, for example, to a speed threshold, which can be specified as a proportion, e.g. in percent, of a maximum speed. In this example, the hand-held power tool is therefore switched off as soon as an actual speed and / or the variable target speed falls below the speed threshold. In another example, the switch-off criterion relates to a voltage threshold, which describes a minimum permissible actual voltage of the energy storage unit. In this example, the hand-held power tool is therefore switched off as soon as the actual voltage of the energy storage unit falls below the voltage threshold.In another example, the shutdown criterion relates to a time threshold that specifies a maximum permissible period during which the handheld power tool may be operated at a target speed that is reduced compared to an input speed. In this example, the handheld power tool is shut down as soon as this permissible period is exhausted. In all of these examples, the variable target speed can be continuously reduced until the respective shutdown criterion is met. The handheld power tool is then shut down.

[0013] The control unit according to the invention can be installed so firmly within the handheld power tool that it is not removed when replacing a rechargeable battery or battery. This has the advantage that the control unit according to the invention interacts with any rechargeable battery or battery coupled to the handheld power tool. Alternatively, the control unit according to the invention can be designed as a component of a rechargeable battery assembly or a battery assembly. In this variant, the control unit, together with the associated rechargeable battery or battery, can be decoupled from the rest of the handheld power tool and replaced.

[0014] According to one embodiment, the target speed specification device comprises an input speed input interface for receiving an input speed. In addition, the target speed specification device is designed to provide the variable target speed based on the actual voltage value, the limit voltage value, and the input speed. The input speed is the speed requested by a user of the hand-held power tool. This occurs, for example, when the user activates a corresponding switch on the hand-held power tool. The input speed can also be referred to as the maximum target speed. The user therefore specifies a maximum target speed. In summary, the user can operate the hand-held power tool in the usual way by specifying the input speed and, in this context, specifically select a speed level.

[0015] The target speed specification device can be configured to determine a variable target speed that differs from an input speed by a value proportional to a difference between the actual voltage value and the limit voltage value. In particular, the variable target speed is reduced by this value compared to the input speed. In this way, a target speed can be determined easily and reliably that takes into account both the actual voltage value and the input speed specified by the user.

[0016] The target speed specification device can alternatively or additionally be configured to determine a correction factor based on the actual voltage value and the limit voltage value, and to determine the variable target speed based on the correction factor and the input speed. In this context, in particular, the input speed is multiplied by the correction factor to determine the target speed. In this way, a target speed can be determined easily and reliably, taking into account both the actual voltage value and the input speed specified by the user. Furthermore, the calculations required to determine the correction factor can be easily performed automatically.

[0017] In one variant, the correction factor is limited to values ​​from 0 to 1. The input speed specified by the user is therefore maintained or reduced. As already explained, this leads to an increase in battery life or accumulator life. At the same time, the control unit behaves predictably from the user's perspective. Furthermore, the calculation of such a correction factor can be implemented simply and efficiently. The target speed specification device can also be designed to determine the correction factor depending on a difference between the actual voltage value and the limit voltage value. The actual voltage value is therefore compared with the specified limit voltage value. It is possible for the difference to be a standardized difference. During standardization, the determined difference is divided by a standardization reference. For example, the difference can be standardized with the specified limit voltage value.Of course, it is also possible to use a separate voltage value as a standardization reference. This allows the accumulator or battery's charge level, described by the actual voltage value, to be easily and reliably taken into account when determining the target speed.

[0018] The correction factor can be variable. This means that the correction factor can assume different values ​​at different times. In particular, the correction factor is always changed continuously, i.e., without correction factor jumps. In a case where the correction factor is limited to values ​​from 0 to 1, the correction factor can be continuously adjusted between these values. This allows a variable target speed to be specified easily and reliably.

[0019] In one embodiment, the correction factor is set to the value 1 if the actual voltage value is greater than the limit voltage value by at least a predetermined difference. In this context, it is assumed that the charge level of the battery or accumulator is sufficiently high as long as the actual voltage value is greater than the limit voltage value by at least the predetermined difference. Therefore, no measures to extend the battery or accumulator runtime are required. If the correction value has the value 1, the target speed corresponds to the input speed. Therefore, the input speed is not reduced.

[0020] The target speed setting device can determine the correction factor such that the actual voltage value of the energy storage unit is kept at the limit voltage value. The target speed setting device is therefore designed to determine the target speed using the correction factor such that the actual voltage value of the energy storage unit is kept at the limit voltage value. This can be done within the framework of a control system in which the correction factor is used as a manipulated variable. In simple terms, when the charge level of the battery or accumulator decreases, which is normally expressed in a decreasing actual voltage value, the target speed is reduced using the correction factor until the actual voltage value is kept at the limit voltage value. The actual voltage value is therefore regulated to the limit voltage value. This results in a particularly long battery or accumulator runtime.

[0021] The control unit can also include an activation interface for selectively activating and deactivating the target speed setting device. The target speed setting device can thus be activated or deactivated by a user as needed. If the target speed setting device is deactivated, it has no influence on the target speed. In other words, the correction factor is 1.

[0022] The activation interface can be coupled to a user interface on the handheld machine tool so that the user can operate the user interface to selectively activate and deactivate it.

[0023] It is also possible to pair the activation interface with a user's mobile electronic device, such as a smartphone, smartwatch, or tablet. The user can then activate or deactivate the target speed setting device via the mobile electronic device.

[0024] In one variant, the control unit comprises a shutdown device for shutting down the handheld power tool when the actual voltage value falls below a predetermined or specifiable ratio between the actual voltage value and a nominal voltage value of the energy storage unit. In this way, deep discharge of the electrical energy storage unit can be avoided. This protects the electrical energy storage unit and increases its service life accordingly. The predetermined or specifiable ratio is, for example, between two-thirds and three-quarters of the nominal voltage. Shutdown preferably occurs when the actual voltage value falls below 70% of the nominal voltage value.

[0025] The target operating parameter can be a current value. The drive unit, in particular the drive motor unit, is thus controlled via a current value. In particular, the drive unit comprises a DC motor. The DC motor can be designed as a brushless DC motor. Since such DC motors are electronically commutated, they are also referred to as electronically commutated motors or EC motors.

[0026] In one alternative, the target speed setting device comprises an actual torque input interface for obtaining an actual torque value of the handheld power tool. The target speed setting device is designed to adjust the variable target speed such that the torque remains constant or is kept in a range above a predetermined minimum torque. The minimum torque can be specified by the user and selected depending on the machining task to be performed. Alternatively, the minimum torque is fixed. In this context, the actual torque value can be provided, for example, by a torque detection unit. The torque detection unit can comprise a torque sensor.Alternatively, the torque detection unit can comprise a motor model that describes the drive motor and be configured to calculate and provide the actual torque value using a characteristic value describing a motor current and the motor model. Overall, therefore, the speed of the handheld power tool can be reduced using the target speed specification device, while the torque can be kept constant, or maintained within a range above a predetermined minimum torque, or increased. In this way, the power consumption of the handheld power tool is reduced, thus increasing the battery life or accumulator life, while at the same time limiting the use of the handheld power tool only to a comparatively small extent.The extension of the battery life or accumulator life achieved by reducing the target speed can thus be used to complete machining tasks using the hand-held machine tool.

[0027] In another alternative, the target speed setting device also comprises an actual torque input interface for obtaining an actual torque value of the handheld power tool. However, the target speed setting device is now designed to adjust the variable target speed such that the torque increases. In this context, the actual torque value can be provided, for example, by a torque detection unit. The torque detection unit can comprise a torque sensor. Alternatively, the torque detection unit can comprise a motor model that describes the drive motor and can be designed to calculate and provide the actual torque value using a characteristic value describing a motor current and the motor model.Overall, the target speed setting device can be used to reduce the speed of the handheld power tool to such an extent that the torque can increase with an overall reduction in mechanical power. Compared to the aforementioned alternative, the speed of the handheld power tool is further reduced. This increases battery life or accumulator runtime, while at the same time restricting the use of the handheld power tool only to a relatively small extent. The extension of battery life or accumulator runtime achieved by lowering the target speed can thus be used to complete machining tasks using the handheld power tool.

[0028] In one variant, the control unit comprises a wireless interface for exchanging at least one parameter wirelessly transmitted from a user's terminal and / or wirelessly transmitted to a user's terminal, selected from a group of parameters, consisting of: - receiving the activation or deactivation of the target speed

[0029] Pre-set facility,

[0030] - Receiving the ratio between the actual voltage value and the nominal voltage value of the energy storage unit,

[0031] - Sending an actual voltage value of the energy storage unit,

[0032] - Sending a nominal voltage value of the energy storage unit.

[0033] The user is thus informed about one or more of these parameters. This can serve as a basis for planning their work with the hand-held power tool. Furthermore, these parameters make the behavior of the hand-held power tool understandable for the user. Therefore, from the user's perspective, the hand-held power tool's behavior is not surprising.

[0034] Furthermore, the object is achieved by a drive unit for a hand-held power tool, which has a control unit according to the invention, an interface for an electrical energy storage unit, and a drive motor unit. The control unit is signal-coupled to the interface for the energy storage unit in such a way that an actual voltage value of the energy storage unit can be provided at the actual voltage input interface. Furthermore, the control unit is signal-coupled to the drive motor unit in such a way that the target operating parameter can be provided to the drive motor unit. In the simplest case, the drive motor unit is a drive motor. Unlike in the prior art, in a drive unit of this type, the target speed is not specified directly by the user, but is determined and provided as a variable target speed by the target speed specification device.This occurs as a function of the actual voltage value and the limit voltage value. In other words, the target speed is specified as a function of the state of charge of the electrical energy storage unit. In particular, in this context the target speed can be reduced if a comparatively low state of charge of the electrical energy storage unit is determined using the actual voltage value. As a result, the power drawn from the electrical energy storage unit is also reduced. A current provided by the electrical energy storage unit decreases in this context. As a result, a voltage drop across an internal electrical resistance of the energy storage unit decreases. In addition, the voltage drop across the internal resistance of the energy storage unit, i.e. across the energy storage unit, is reduced. This means that an existing electrical energy storage unit can be used for longer.If the handheld power tool is shut down as soon as the actual voltage drops below a specified threshold, the shutdown occurs correspondingly later. This increases the accumulator or battery life.

[0035] In this context, the interface for the electrical energy storage unit can be designed in such a way that the electrical energy storage unit can be easily replaced by a user. In this context, it is also referred to as a removable accumulator or a removable battery.

[0036] Furthermore, the object is achieved by a hand-held power tool with a drive unit according to the invention and a tool or a tool holder. The drive unit is coupled to the tool or the tool holder in terms of drive. In such a hand-held power tool, the target speed can therefore be reduced if a comparatively low charge level of the electrical energy storage unit is determined using the actual voltage value. This means that an existing electrical energy storage unit can be used for longer. In the event that the hand-held power tool is switched off as soon as the actual voltage value falls below a predetermined threshold, such a switch-off occurs correspondingly later. The accumulator or battery life thus increases.

[0037] Additionally, the object is achieved by a method for operating a handheld power tool. The handheld power tool comprises an electric drive motor unit and an electrical energy storage unit for supplying the drive motor unit with electrical energy. The method comprises the following steps: - Detecting an actual voltage value of the energy storage unit,

[0038] - Obtaining a limit voltage value for the energy storage unit,

[0039] - Determining a variable target speed for the drive motor unit of the hand-held machine tool based on the actual voltage value and the limit voltage value, and

[0040] - Operating the hand-held machine tool using the variable target speed.

[0041] In this context, the actual voltage value at least indirectly describes a state of charge of the electrical energy storage unit. The limit voltage value is fixed. In other words, the target speed is specified as a function of the state of charge of the electrical energy storage unit. In particular, in this context the target speed can be reduced if a comparatively low state of charge of the electrical energy storage unit is determined using the actual voltage value. As a result, the power drawn from the electrical energy storage unit is also reduced. A current provided by the electrical energy storage unit decreases in this context. As a result, a voltage drop across an internal electrical resistance of the energy storage unit decreases. In addition, the voltage drop across the internal resistance of the energy storage unit, i.e. across the energy storage unit, decreases.This means that an existing electrical energy storage unit can be used for longer. If the handheld power tool is shut down as soon as the actual voltage drops below a specified threshold, the shutdown occurs correspondingly later. This increases the accumulator or battery life. No user intervention is required.

[0042] The method according to the invention can therefore also be referred to as power saving mode.

[0043] The power saving mode can be permanently activated. Alternatively, the power saving mode, i.e. the application of the method according to the invention, can be selectively activated or deactivated by a user. In one embodiment, the method additionally comprises obtaining an input speed for the hand-held power tool and determining the target speed based on the actual voltage value, the limit voltage value and the input speed. The input speed is the speed requested by a user of the hand-held power tool. This is done, for example, by the user actuating a corresponding switch on the hand-held power tool. The input speed can also be referred to as the maximum target speed. The user therefore specifies a maximum target speed.In summary, the user can operate the hand-held machine tool in the usual way by specifying the input speed and, in this context, select a specific speed level.

[0044] Furthermore, the method can include determining a correction factor depending on the actual voltage value and the limit voltage value, and determining the variable target speed based on the correction factor and the input speed. In this context, in particular, the input speed is multiplied by the correction factor to determine the target speed. In this way, a target speed can be easily and reliably determined that takes into account both the actual voltage value and the input speed specified by the user. Furthermore, the calculations required to determine the correction factor can be easily performed automatically.

[0045] The correction factor can be limited to values ​​from 0 to 1. This means that the input speed specified by the user is reduced if necessary. As already explained, this leads to an increase in battery life or accumulator runtime. At the same time, the control unit behaves predictably from the user's perspective. Furthermore, the calculation of such a correction factor is simple and efficient.

[0046] The method can also include determining the correction factor depending on the difference between the actual voltage value and the limit voltage value. The actual voltage value is compared with the specified limit voltage value. The difference may be a standardized difference. During standardization, the determined difference is divided by a standardization reference. For example, the difference may be standardized with the specified limit voltage value. Of course, it is also possible to use a separate voltage value as a standardization reference. This allows the charge level of the accumulator or battery, described by the actual voltage value, to be easily and reliably taken into account when determining the target speed.

[0047] Furthermore, the method can include setting the correction factor to the value 1 if the actual voltage value is greater than the limit voltage value by at least a predetermined difference. In this context, it is assumed that the state of charge of the battery or accumulator is sufficiently high as long as the actual voltage value is greater than the limit voltage value by at least the predetermined difference. Therefore, no measures to extend the battery or accumulator runtime are required. If the correction value has the value 1, the target speed corresponds to the input speed. Therefore, there is no reduction in the input speed.

[0048] In one embodiment, the method comprises determining the correction factor such that the actual voltage of the energy storage unit is maintained at the limit voltage value. The target speed specification device is thus designed to determine the target speed using the correction factor such that the actual voltage of the energy storage unit is maintained at the limit voltage value. This can be done within the framework of a control system in which the correction factor is used as a manipulated variable. In simple terms, when the charge level of the battery or accumulator decreases, which is normally expressed in a decreasing actual voltage value, the target speed is reduced using the correction factor to such an extent that the actual voltage is maintained at the limit voltage value. The actual voltage is thus regulated to the limit voltage value. This results in a particularly long battery or accumulator runtime.The method can be started as soon as the actual voltage value of the energy storage unit falls below an activation threshold. The activation threshold is preferably below the nominal voltage of the energy storage unit and above a shutdown threshold. The method according to the invention is therefore started when the electrical energy storage unit is discharged to a predetermined extent that corresponds to the activation threshold. Thus, the method according to the invention is only carried out in situations in which the electrical energy storage unit is already so deeply discharged that it is expedient to extend the battery life or accumulator life using the method according to the invention.

[0049] The invention is explained below using various embodiments shown in the accompanying drawings. They show:

[0050] Figure 1 shows a hand-held power tool according to the invention with a drive unit according to the invention, which comprises a control unit according to the invention, by means of which a method according to the invention can be carried out,

[0051] Figure 2 shows the control unit according to the invention in a detailed view,

[0052] Figures 3 to 6 are diagrams illustrating various alternatives of the method according to the invention,

[0053] Figure 7 shows an optional additional target speed setting device for the hand-

[0054] Machine tool from Figure 1, and

[0055] Figure 8 is a diagram explaining the further target speed

[0056] Pre-determined facility.

[0057] Figure 1 shows a hand-held power tool 10, which in the example shown is designed as a so-called cordless screwdriver.

[0058] The hand-held power tool 10 has an angled housing 12. A first end region 14 of the housing 10 is designed as a handle that can be grasped by a user of the hand-held power tool 10.

[0059] At an opposite end of the angled housing 12, a tool holder 16 is rotatably mounted in the housing 12.

[0060] A tool 18 is accommodated in the tool holder 16. In this case, the tool 18 is a drill.

[0061] In addition, the hand-held machine tool 10 has a drive unit 20.

[0062] The drive unit 20 comprises a drive motor unit 22, a control unit 24 and an interface 26 for an electrical energy storage unit.

[0063] The drive motor unit 22 comprises a drive motor 28, which in this case is designed as an electric direct current machine. An output shaft 30 of the drive motor 28 is coupled in a torque-conducting manner to the tool holder 16 and thus, via the tool holder 16, to the tool 18.

[0064] Generally speaking, the drive unit 20 is thus drive-coupled to the tool holder 16. After the tool 18 is received in the tool holder 16, the drive unit 20 is also drive-coupled to the tool 18.

[0065] The control unit 24 is signal-coupled to the drive motor unit 22, i.e., to the drive motor 28. As will be explained later, a desired operating parameter can be provided to the drive motor unit 22 by the control unit 24 via this signal-coupled connection.

[0066] Furthermore, the control unit 24 is signal-coupled to the interface 26. This will also be explained later. The hand-held power tool 10 further comprises an electrical energy storage unit 32, which is arranged inside the housing 12 in such a way that it can be optionally removed by a user. In the present example, the electrical energy storage unit 32 is arranged in the first end region 14.

[0067] In the assembled state, the electrical energy storage unit 32 is coupled to the interface 26.

[0068] Details of the control unit 24 are shown in Figure 2.

[0069] The control unit 24 comprises a target speed setting device 34.

[0070] The target speed setting device 34 has an actual voltage input interface 36 for receiving an actual voltage value USE of the electrical energy storage unit 32.

[0071] The actual voltage input interface 36 is a component of the interface 26 for the electrical energy storage unit.

[0072] In addition, the target speed setting device 34 has a limit voltage input interface 38 for receiving a limit voltage value UG. In this context, the limit voltage input interface 38 can be coupled to a memory unit on which the limit voltage value UG is stored.

[0073] In the illustrated example, the nominal voltage of the electrical energy storage unit 32 is 18 volts. The limit voltage value UG is 15 volts.

[0074] In addition, the target speed setting device 34 comprises an input speed input interface 40 for receiving an input speed NE.

[0075] In the example shown, an actuation switch 42 of the hand-held power tool 10 is signal-coupled to the input speed interface 40. A user can operate the hand-held power tool 10 in the usual way using the actuation switch 42.

[0076] The control unit 24 is designed to provide a variable target speed Ns based on the actual voltage value USE, the limit voltage value UG and the input speed NE.

[0077] For this purpose, a difference D between the actual voltage value USE and the limit voltage value UG is first determined.

[0078] In the event that the difference D does not exceed a specified difference value Dmax, the target speed Ns corresponds to the input speed NE.

[0079] Only when the difference D exceeds the specified difference value Dmax, a target speed Ns is determined that deviates from the input speed NE.

[0080] In the illustrated embodiment, the specified differential value is 0 volts. The limit voltage value UG is, as already mentioned, 15 volts. Therefore, as long as the actual voltage value USE is greater than 15 volts, the target speed Ns corresponds to the input speed NE.

[0081] If the actual voltage value USE reaches 15 volts, a correction factor K between 0 and 1 is determined and the target speed Ns is determined by multiplying the input speed NE by the correction factor K.

[0082] In this example, the correction factor is 1 as long as the actual voltage value USE is above 15 volts.

[0083] Furthermore, the correction factor K can be defined such that it is zero at an actual voltage value of 14 volts. Between these two points, the correction factor K can be proportional to the actual voltage value USE. The correction factor K can be stored, for example, in the form of a look-up table on the control unit 24. More precisely, the look-up table can be stored on a voltage regulator 43.

[0084] Alternatively, it is possible that the correction factor K depends on the difference D. In this context, the correction factor K can also be linear.

[0085] The correction factor K can be understood as a control variable. Using the voltage regulator 43, the correction factor K is determined such that the actual voltage value USE corresponds to the limit voltage value UG. The difference D should therefore be 0.

[0086] In other words, the actual voltage value USE is regulated to the limit voltage value UG.

[0087] In all of the above variants, a target speed Ns is determined based on the actual voltage value USE, the limit voltage value UG, and the input speed NE. This represents an output variable of the target speed setting device 34.

[0088] The control unit 24 further comprises a speed control device 44.

[0089] The speed control device 44 comprises an actual speed input interface 46 for receiving an actual speed Ni of the hand-held machine tool 10.

[0090] The actual speed Ni corresponds to a speed of the tool 18. This actual speed Ni is provided by a speed detection unit 48. The speed detection unit 48 can comprise a speed sensor. Alternatively, the speed detection unit 48 comprises a field model, so that the actual speed Ni can be provided without using a speed sensor.

[0091] In addition, the speed control device 44 comprises a target speed input interface 50. The target speed setting device 34 and the speed control device 44 are signal-technically coupled via the target speed input interface 50, so that the target speed Ns can be provided by means of the target speed setting device 34 at the target speed input interface 50.

[0092] The speed control device 44 also comprises an output interface 52 for outputting a target operating parameter Ps for the hand-held machine tool 10 to be controlled, more precisely for the drive motor 28.

[0093] In this case, the target operating parameter Ps is a current parameter, i.e. a target current.

[0094] The speed control device 44 is designed to provide the target operating parameter Ps at the output interface 52 in such a way that the actual speed Ni is adjusted to the target speed Ns. This occurs in a controlled manner. The speed control device 44 thus comprises a speed controller 54. This can be designed as a so-called PI controller.

[0095] In addition, the control unit 24 comprises an operating parameter control unit 56.

[0096] The operating parameter control unit 56 has a target parameter input interface 58 and an actual parameter input interface 60.

[0097] As already explained, operating parameters are current parameters.

[0098] Consequently, the target parameter input interface 58 is signal-connected to the output interface 52 of the speed control device 44.

[0099] The actual parameter input interface 60 is connected to a current sensor 62.

[0100] The current sensor 62 measures a current, ie an actual operating parameter Pi, with which the drive motor 28 is controlled.

[0101] As already explained, the drive motor 28 is a DC motor. It is controlled by a pulse-width modulated signal. Based on a difference between the target operating parameter Ps, which is provided at the target parameter input interface 58, and the actual operating parameter Pi measured by the current sensor 62, a duty cycle for controlling the drive motor 28 can be set by means of a current controller 64 such that the actual operating parameter Pi approximates the target operating parameter Ps.

[0102] Optionally, the target speed setting device 34 also includes an actual torque input interface 66.

[0103] The actual torque input interface 66 is signal-coupled to a torque detection unit 68, which determines a torque applied to the tool 18. For this purpose, the torque detection unit 68 can comprise a torque sensor. Alternatively, the torque detection unit 68 can comprise a motor model that describes the drive motor 28 and can be configured to calculate and provide the actual torque value using a characteristic value describing a motor current and the motor model.

[0104] Optionally, the target speed setting device 34 can be designed to set the variable target speed Ns such that the torque remains constant or is kept in a range above a predetermined minimum torque.

[0105] Starting from the input speed NE, the target speed Ns is only reduced to such an extent that the torque remains constant or is kept in a range above a specified minimum torque.

[0106] To put it simply, the speed is reduced while the torque is maintained.

[0107] Alternatively, it is also possible to reduce the target speed Ns to such an extent that the torque increases. This will be explained in more detail below. The control unit 24 also includes an activation interface 70, via which the target speed setting device 34 can be selectively activated or deactivated.

[0108] In the illustrated embodiment, the activation interface 70 is coupled to an activation switch 72, which can be selectively actuated by a user of the hand-held power tool 10.

[0109] The control unit 24 further includes a shutdown device 74. The shutdown device 74 is coupled to the actual voltage input interface 36. Furthermore, a shutdown voltage is stored on the shutdown device 74. The shutdown device 74 can thus be used to shut down the hand-held power tool 10 as soon as the actual voltage USE falls below the shutdown voltage.

[0110] Alternatively, a predetermined ratio between the actual voltage value USE and a nominal voltage value of the energy storage unit 32 can be stored on the shutdown device 74 and the hand-held power tool 10 can be switched off as soon as this ratio is undershot.

[0111] In addition, the control unit 24 has a wireless interface 76.

[0112] The wireless interface 76 is designed to wirelessly transmit parameters to a user's terminal device and to receive parameters from the terminal device.

[0113] The actual voltage value USE of the energy storage unit 32 and / or a nominal voltage value of the energy storage unit 32 can be provided by means of the wireless interface 76, ie sent to the user's terminal device.

[0114] A signal for activating or deactivating the target speed setting device 34 can also be received via the wireless interface 76. Furthermore, it is possible to receive a minimum voltage value or a ratio between the actual voltage value USE and the nominal voltage value of the energy storage unit 32 via the wireless interface 76.

[0115] The hand-held power tool 10 can be operated using a method for operating a hand-held power tool 10. This is explained below with reference to Figure 3.

[0116] As part of the method, the actual voltage value USE of the energy storage unit 32 is first recorded.

[0117] Furthermore, an input speed NE is obtained.

[0118] As already explained, the limit voltage value UG is specified.

[0119] Consequently, the target speed Ns is determined based on the actual voltage value USE, the limit voltage value UG and the input speed NE.

[0120] The hand-held machine tool 10 is operated using this target speed Ns.

[0121] As already explained, a correction factor K is determined by which the input speed NE is multiplied.

[0122] The process is only started when the actual voltage value USE falls below an activation threshold.

[0123] This can be clearly seen in Figure 3. In this context, Figure 3 plots the target speed Ns, the corresponding actual torque M, the actual operating parameter Pi (in this case, an actual current), and the actual voltage value USE of the electrical energy storage unit over an operating time t. The limit voltage value UG is also shown as a horizontal dashed line.

[0124] The process is started at the operating time designated tstan. At this point in time, the actual voltage value USE reaches an activation threshold, which in this case is 16.5 volts, and is thus below the nominal voltage of the energy storage unit 32, which in this case is 18 volts.

[0125] As already explained, the correction factor K is 1 as long as the actual voltage value USE is greater than 15 volts, ie greater than the limit voltage value UG.

[0126] In this example, the actual voltage value USE reaches the time t re d, 15 volts. At this point in time, the actual voltage value USE corresponds to the limit voltage value UG.

[0127] This means that from this point on, the target speed Ns is reduced from the input speed NE using the correction factor K. As a result, the target operating parameter P s and the actual operating parameter Pi is reduced. The current drawn from the electrical energy storage unit 32 thus decreases over the remaining operating time t.

[0128] This results in an extended battery runtime compared to a situation in which the target speed Ns is not reduced.

[0129] However, the actual torque M is kept constant, as can be seen in Figure 3. Thus, work can continue with the hand-held machine tool 10.

[0130] In the event that the torque detection unit 68 comprises a torque sensor, the actual torque can be kept constant on the basis of a measured value generated by the torque sensor, e.g., by means of a torque control.

[0131] In an alternative in which the torque detection unit 68 does not comprise a torque sensor, the actual torque can be determined based on the actual speed Ni and the actual operating parameter Pi, which in this case is an actual current. In other words, a motor model is used that describes the drive motor 28. This can exploit the fact that the actual voltage value USE corresponds to the limit voltage value UG and is therefore known and constant. An electrical power can thus be determined based on the product of the actual operating parameter Pi and the limit voltage value UG. Based on this, it is assumed that the electrical power decreases proportionally to the mechanical power provided at the actual speed Ni. The actual torque can thus be calculated.

[0132] In this example, the hand-held power tool 10 is only shut down when the speed falls below a specified minimum. This occurs at time tAb.

[0133] An alternative operation of the hand-held power tool 10 is explained below with reference to Figure 4. Only the differences compared to the method explained with reference to Figure 3 are discussed.

[0134] The procedure is started again at the operating time designated by tstan.

[0135] As before, the correction factor K is 1 as long as the actual voltage value USE is greater than 15 volts, ie greater than the limit voltage value UG. The actual voltage value USE reaches the limit voltage value UG again at the time t re d, 15 volts. At this point in time, the actual voltage value USE corresponds to the limit voltage value UG.

[0136] This means that from this point on, the target speed Ns is reduced based on the input speed NE using the correction factor K. In contrast to the example in Figure 3, the target speed Ns is now reduced less. To illustrate this, the target speed Ns from the example in Figure 3 is plotted in Figure 4 with a wide dashed line.

[0137] As a result, the target operating parameter Ps and the actual operating parameter Pi are also reduced. The current drawn from the electrical energy storage unit 32 thus decreases over the remaining operating time t.

[0138] At the same time, in the example shown in Figure 4, the actual torque is also reduced. This can result, for example, from the currently performed machining task for which the hand-held power tool 10 is being used. Compared to the example shown in Figure 3, less mechanical power is provided by the hand-held power tool 10. This results in a longer battery runtime compared to the example shown in Figure 3.

[0139] In the example from Figure 4, the hand-held power tool 10 is also only switched off when a specified minimum speed is undershot. This occurs at time tAb, which is now reached later than in the example from Figure 3.

[0140] Another alternative operation of the hand-held power tool 10 is explained below with reference to Figure 5. Only the differences compared to the method explained with reference to Figures 3 and 4 are discussed.

[0141] The procedure is started again at the operating time designated by tstan.

[0142] As before, the correction factor K is 1 as long as the actual voltage value USE is greater than 15 volts, ie greater than the limit voltage value UG. The actual voltage value USE reaches the limit voltage value UG again at the time t re d, 15 volts. At this point in time, the actual voltage value USE corresponds to the limit voltage value UG.

[0143] This means that from this point on, the target speed Ns is reduced based on the input speed NE using the correction factor K. In contrast to the example in Figure 3, the target speed Ns is now reduced more significantly. To illustrate this, the target speed Ns from the example in Figure 3 is plotted in Figure 5 with a wide dashed line.

[0144] As a result, the target operating parameter Ps and the actual operating parameter Pi are also reduced. The current drawn from the electrical energy storage unit 32 thus decreases over the remaining operating time t.

[0145] At the same time, however, the actual torque increases in the example from Figure 5. This can result, for example, from the currently executing machining task for which the hand-held power tool 10 is being used. This partially compensates for the effect of the decreasing actual operating parameter Pi, so that the actual operating parameter Pi decreases less sharply in the example from Figure 5 than in the examples from Figures 3 and 4.

[0146] Compared to the examples in Figures 3 and 4, higher mechanical power is provided by the hand-held power tool 10. This results in a shorter battery runtime compared to the examples in Figures 3 and 4.

[0147] In the example from Figure 5, the hand-held power tool 10 is also only switched off when a specified minimum speed is undershot. This occurs at time tAb, which is now reached earlier than in the example from Figure 3 and the example from Figure 4.

[0148] Another alternative operation of the hand-held power tool 10 is explained below with reference to Figure 6. Only the differences compared to the method explained with reference to Figures 3 to 5 are discussed.

[0149] The procedure is started again at the operating time designated by tstan.

[0150] In contrast to the examples in Figures 3 to 5, however, the method now includes a warning for the user that the target speed Ns will soon be reduced.

[0151] The warning is triggered as soon as the actual voltage value USE reaches a voltage warning value Ui, which in this case is 15.5 volts. In the example shown, the voltage warning value Ui is reached at the warning time ti.

[0152] The warning consists of the target speed Ns being reduced abruptly, for example, by 15%. The amount of the abrupt reduction is selected such that, on the one hand, it can be easily noticed by a user of the hand-held power tool 10, while, on the other hand, only slightly disrupting a currently executing machining task.

[0153] As a result, the target operating parameter Ps and the actual operating parameter Pi are also reduced. The current drawn from the electrical energy storage unit 32 thus drops abruptly. This leads to a reduction in the voltage drop across an internal resistance of the energy storage unit 32, so that the actual voltage value USE increases briefly.

[0154] Work can then continue at the speed reduced by 15%.

[0155] As before, the correction factor K is 1 as long as the actual voltage value USE is greater than 15 volts, ie greater than the limit voltage value UG.

[0156] If the actual voltage value USE returns to the time t red, reaches 15 volts, i.e. the limit voltage value UG, the target speed Ns is reduced again from the input speed NE by means of the correction factor K, as described, for example, in connection with Figure 3.

[0157] An optional additional target speed setting device 78 for the hand-held power tool 10, more specifically for the control unit 24, is shown in Figure 7. It is emphasized that the additional target speed setting device 78 is optional. To distinguish the target speed setting device 78 from the target speed setting device 34, the target speed setting device 78 is referred to as the "additional" target speed setting device 78.

[0158] The additional target speed setting device 78 can be used as an alternative to the target speed setting device 34. It is also possible to use the additional target speed setting device 78 and the target speed setting device 34 in combination. In this case, a target speed Ns determined by the additional target speed setting device 78 and a target speed Ns determined by the target speed setting device 34 are compared, and the smaller of these target speeds Ns is always used as the input variable at the target speed input interface 50.

[0159] The further target speed setting device 78 serves to allow the user of the hand-held power tool 10 to work with a comparatively high torque without exceeding a predetermined limit current value IG of the electrical energy storage unit 32.

[0160] In other words, the additional target speed setting device 78 serves to provide a comparatively high torque to the output shaft 30 and thus to the tool holder 16 and the tool 18 by means of the drive motor 28. In this case, the specified limit current value IG of the electrical energy storage unit 32 is not exceeded.

[0161] In this context, it should be noted that a limit current value IG is usually specified for an electrical energy storage unit 32, which must not be exceeded during operation of the electrical energy storage unit 32 in order to avoid damage and / or functional impairment of the electrical energy storage unit 32. The limit current value IG can therefore also be referred to as the maximum current.

[0162] The further target speed setting device 78 has an actual current input interface 80 for receiving an actual current ISE of the electrical energy storage unit 32. The actual current ISE is the current that is provided by the electrical energy storage unit 32 at a given time, ie, is drawn from the electrical energy storage unit 32.

[0163] The actual current input interface 80 can be a component of the interface 26 for the electrical energy storage unit.

[0164] In addition, the further target speed setting device 78 has a limit current input interface 82 for receiving the limit current value IG. In this context, the limit current input interface 82 can be coupled to a memory unit on which the limit current value IG is stored.

[0165] In the illustrated embodiment, the limit current value IG is 50 amperes. Furthermore, the additional target speed setting device 78 includes an input speed interface 84 for receiving the input speed NE.

[0166] In the example shown, an actuating switch 42 of the hand-held machine tool 10 is signal-coupled to the input speed input interface 84.

[0167] As already explained, a user can operate the hand-held power tool 10 in the usual way using the operating switch 42.

[0168] The further target speed setting device 78 is designed to provide a variable target speed Ns based on the actual current value ISE, the limit current value IG and the input speed NE.

[0169] For this purpose, a difference between the limit current value lo and the actual current value ISE is first determined.

[0170] In the event that the difference between the limit current value IG and the actual current value ISE does not fall below a specified difference value, the target speed Ns corresponds to the input speed NE.

[0171] Only when the difference between the limit current value IG and the actual current value ISE falls below the specified difference value, a target speed Ns is determined that deviates from the input speed NE.

[0172] In one example, the specified differential value is 1 ampere. Therefore, as long as the actual current value ISE is 1 ampere or more below the limit current value IG, the target speed Ns corresponds to the input speed NE.

[0173] However, if the difference between the limit current value IG and the actual current value ISE falls below the specified difference value, e.g. 1 ampere, the target speed Ns is reduced, i.e. regulated down, such that the actual current value ISE does not exceed the limit current value IG. In particular, the actual current value ISE is regulated to the limit current value IG. It is understood that during such a regulation, the limit current value IG can theoretically, but in practice, be exceeded. These are so minor, however, that in this case we are nevertheless talking about regulation to the limit current value IG and preventing the limit current value IG from being exceeded.

[0174] To determine a reduced or down-regulated target speed Ns, a correction factor K' between 0 and 1 can be determined. The target speed Ns is then determined by multiplying the input speed NE by the correction factor K'.

[0175] In this example, the correction factor K' is 1 as long as the actual current value ISE is below the limit current value IG by the specified difference value or more.

[0176] If the difference between the limit current value IG and the actual current value ISE falls below the specified difference value, the correction factor K' is correspondingly smaller than 1. The correction factor K' must be determined in such a way that, based on the target speed Ns determined using the correction factor K', an actual current value ISE results that corresponds to or lies below the limit current value IG.

[0177] The correction factor K' can be a function of the actual current value ISE or the difference between the limit current value IG and the actual current value ISE. For example, the correction factor K' is proportional to the actual current value ISE or proportional to the difference between the limit current value IG and the actual current value ISE.

[0178] Alternatively or additionally, the correction factor K' can be determined using a look-up table. The look-up table can be stored on the control unit 24 or the additional target speed setting device 78. More specifically, the look-up table can be stored on a current controller.

[0179] Overall, the correction factor K' can be understood as a control variable. Using the current controller, the correction factor K' is determined such that the actual current value ISE corresponds to, but does not exceed, the limit current value IG. The difference D should therefore be 0.

[0180] In other words, the actual current value ISE is controlled to the limit current value IG. For this purpose, a PI controller or a PID controller is used, for example.

[0181] A target speed Ns is determined based on the actual current value ISE, the limit current value IG, and the input speed NE. This represents an output variable of the further target speed setting device 78.

[0182] The further target speed input interface 50 of the speed control device 44 is signal-coupled to the further target speed setting device 78 and the speed control device 44, so that the target speed Ns can be provided to the target speed input interface 50 by means of the further target speed setting device 78. Furthermore, reference can be made to the above explanations regarding the speed control device 44.

[0183] As already explained, the additional target speed setting device 78 comes into play when a comparatively high torque is to be provided by the drive unit 20. This is typically the case when a machining task is performed using the tool 18 held in the tool holder 16, in which a comparatively high mechanical resistance counteracts a rotational movement of the tool 18.

[0184] In order to overcome such a high mechanical resistance while maintaining a constant rotational speed of the tool 18, the torque provided by the drive unit 20 must be increased. This results in an increase in the current drawn from the electrical energy storage unit 32, i.e., the actual current value ISE.

[0185] In this context, the further target speed setting device 78 ensures that the necessary torque can be provided without overloading the electrical energy storage unit 32, ie without allowing the actual current value ISE to rise above the limit current value IG.

[0186] This is explained in simplified form below with reference to the diagram in Figure 8.

[0187] In this example, a user is working with hand-held power tool 10, with a constant speed. However, a mechanical resistance applied to tool 18 is increasing, causing the actual current value ISE to also increase.

[0188] According to the above explanations, however, the actual current value ISE is regulated to the limit current value IG by specifying a reduced target speed Ns. This prevents overloading of the electrical energy storage unit. It is understood that the method aspects explained in connection with the additional target speed setting device 78 are optional components of the method for operating a hand-held power tool 10.

[0189] List of reference symbols

[0190] 10 hand machine tools

[0191] 12 housings

[0192] 14 first endb er ei ch

[0193] 16 Tool holder

[0194] 18 tools

[0195] 20 drive unit

[0196] 22 Drive motor unit

[0197] 24 Control unit

[0198] 26 Interface for an electrical energy storage unit

[0199] 28 Drive motor

[0200] 30 Output shaft

[0201] 32 electrical energy storage unit

[0202] 34 Target speed setting device

[0203] 36 Actual voltage input interface

[0204] 38 Limit voltage input interface

[0205] 40 Input speed input interface

[0206] 42 operating switches

[0207] 43 voltage regulators

[0208] 44 Speed ​​control device

[0209] 46 Actual speed input interface

[0210] 48 Speed ​​detection unit

[0211] 50 Target speed input interface

[0212] 52 Output interface

[0213] 54 speed controller

[0214] 56 Operating parameter control unit

[0215] 58 Target parameter input interface

[0216] 60 Actual parameter input interface

[0217] 62 Current sensor

[0218] 64 current regulators

[0219] 66 Actual torque input interface

[0220] 68 Torque detection unit

[0221] 70 Activation interface

[0222] 72 activation switches

[0223] 74 Shut-off device

[0224] 76 Wireless interface

[0225] 78 additional target speed setting device

[0226] 80 Actual current input interface

[0227] 82 Limit current input interface

[0228] 84 Input speed input interface of the further target speed

[0229] Preset device D Difference between the actual voltage value and the limit voltage value

[0230] Dmax specified difference value

[0231] K Correction factor

[0232] M Actual torque

[0233] NE input speed

[0234] Ns target speed

[0235] Ni actual speed

[0236] Ps target operating parameters

[0237] Pi Actual operating parameter t Operating time ti Warning time tstan Start time of the process tAb Switch-off time tred Time from which the target speed is reduced

[0238] Ui voltage warning value

[0239] UG limit voltage value

[0240] USE Actual voltage value of the electrical energy storage unit

[0241] IG limit current value of the electrical energy storage unit

[0242] ISE Actual current value of the electrical energy storage unit

[0243] K' correction factor

Claims

Patent claims 1. Control unit (24) for a drive unit (20) of a hand-held power tool (10), with a speed control device (44), comprising - an actual speed input interface (46) for receiving an actual speed (Ni) of the hand-held machine tool (10), - a target speed input interface (50) for receiving a target speed (Ns) of the hand-held machine tool (10), and - an output interface (52) for outputting a target operating parameter (Ps) for the hand-held power tool (10) to be controlled, and with a target speed setting device (34) for setting a variable target speed (Ns) for the hand-held power tool (10) at the target speed input interface (50), comprising - an actual voltage input interface (36) for receiving an actual voltage value (USE) of an electrical energy storage unit (32) for the hand-held power tool (10) and - a limit voltage input interface (38) for obtaining a limit voltage value (UG), wherein the target speed specification device (34) is signal-coupled to the target speed input interface (50) of the speed control device (44), and wherein the target speed specification device (34) is designed to provide the variable target speed (Ns) at the target speed input interface (50) based on the actual voltage value (USE) and the limit voltage value (UG).

2. Control unit (24) according to claim 1, wherein the target speed setting device (34) comprises an input speed input interface (40) for receiving an input speed (NE) and is designed to be based on the actual voltage value (USE), the limit voltage value (UG) and the input speed (NE) to provide the variable target speed (Ns).

3. Control unit (24) according to claim 2, wherein the target speed setting device (34) is designed to determine a correction factor (K) based on the actual voltage value (USE) and the limit voltage value (UG) and to determine the variable target speed (Ns) based on the correction factor (K) and the input speed (NE).

4. Control unit (24) according to claim 3, wherein the correction factor (K) is limited to values ​​from 0 to 1.

5. Control unit (24) according to claim 3 or 4, wherein the target speed setting device (34) is designed to determine the correction factor (K) as a function of a difference (D) between the actual voltage value (USE) and the limit voltage value (UG).

6. Control unit (24) according to claim 4 and 5, wherein the correction factor (K) is set to the value 1, provided that the actual voltage value (USE) differs by at least a predetermined difference value (D max) is greater than the limit voltage value (UG).

7. Control unit (24) according to one of claims 3 to 6, wherein the target speed setting device (34) determines the correction factor (K) such that the actual voltage value (USE) of the energy storage unit (32) is kept at the limit voltage value (UG).

8. Control unit (24) according to one of the preceding claims, comprising an activation interface (70) for selectively activating and deactivating the target speed setting device (34).

9. Control unit (24) according to one of the preceding claims, comprising a shutdown device (74) for switching off the hand-held power tool (10) when a predetermined or predeterminable ratio between the actual voltage value (USE) and a nominal voltage value of the energy storage unit (32) is undershot.

10. Control unit (24) according to one of the preceding claims, wherein the target operating parameter (Ps ) is a current value.

11. Control unit (24) according to one of the preceding claims, wherein the target speed setting device (34) comprises an actual torque input interface (66) for obtaining an actual torque value of the hand-held power tool (10), wherein the target speed setting device (34) is designed to set the variable target speed (Ns) such that the torque remains constant or is maintained in a range above a predetermined minimum torque or increases.

12. Control unit (24) according to one of the preceding claims, comprising a wireless interface (76) for exchanging at least one parameter wirelessly transmitted from a user's terminal and / or wirelessly transmitted to a user's terminal, selected from a group of parameters consisting of: - Receiving the activation or deactivation of the target speed setting device (34), - Receiving the ratio between the actual voltage value (USE) and the nominal voltage value of the energy storage unit (32), - Sending an actual voltage value (USE) of the energy storage unit (32), - Sending a nominal voltage value of the energy storage unit (32).

13. Drive unit (20) for a hand-held power tool (10), with a control unit (24) according to one of the preceding claims, with an interface (26) for an electrical energy storage unit (32) and with a drive motor unit (22), wherein the control unit (24) is signal-coupled to the interface (26) for the energy storage unit (32) in such a way that an actual voltage value (USE) of the energy storage unit (32) can be provided at the actual voltage input interface (36), and the control unit (24) is signal-coupled to the drive motor unit (22) in such a way that the target operating parameter (Ps) can be provided at the drive motor unit (22).

14. Hand-held power tool (10) with a drive unit (20) according to claim 13 and a tool (18) or a tool holder (16), wherein the drive unit (20) is drivingly coupled to the tool (18) or the tool holder (16).

15. A method for operating a hand-held power tool (10) having an electric drive motor unit (22) and an electrical energy storage unit (32) for supplying the drive motor unit (22) with electrical energy, comprising the following steps: - detecting an actual voltage value (USE) of the energy storage unit (32), - Obtaining a limit voltage value (UG) for the energy storage unit (32), - Determining a variable target speed (Ns) for the drive motor unit (22) of the hand-held machine tool (10) based on the actual voltage value (USE) and the limit voltage value (UG), and - Operating the hand-held machine tool (10) using the variable target speed (Ns).

16. The method according to claim 15, comprising: obtaining an input speed (NE) for the hand-held machine tool (10) and determining the target speed (Ns) based on the actual voltage value (USE), the limit voltage value (UG) and the input speed (NE).

17. The method according to claim 16, comprising: determining a correction factor (K) as a function of the actual voltage value (USE) and the limit voltage value (UG) and determining the variable target speed (Ns) based on the correction factor (K) and the input speed (USE).

18. The method according to claim 17, wherein the correction factor (K) is limited to values ​​from 0 to 1.

19. Method according to claim 17 or 18, comprising: determining the correction factor (K) as a function of a difference (D) between the actual voltage value (USE) and the limit voltage value (UG).

20. Method according to claim 18 and 19, comprising: setting the correction factor (K) to the value 1, provided that the actual voltage value (USE) differs by at least a predetermined difference value (D ma x) is greater than the limit voltage value (UG).

21. Method according to one of claims 17 to 20, comprising: determining the correction factor (K) such that the actual voltage (USE) of the energy storage unit (32) is kept at the limit voltage value (UG).

22. Method according to one of claims 15 to 21, wherein the method is started as soon as the actual voltage value (USE) of the energy storage unit (32) falls below an activation threshold.

Images