Systems and methods for power-driven tools with improved thermal motor protection

Abstract

A power-driven tool is provided, comprising a motor, an inverter that drives the motor, a sensor that detects a variable indicating the motor's temperature, a trigger, a power source, and a control unit that communicates with the inverter, sensor, trigger, and power source. The control unit is configured to supply power from the power source to the inverter to drive the motor at a requested power level based on the trigger's deflection when the trigger is pressed. The control unit is further configured to reduce the requested power level to the inverter when the motor temperature reaches a first temperature threshold and to switch off the motor when the motor temperature reaches a second temperature threshold.

Description

Related registrations

[0001] This application claims priority under 35 USC § 119 for the preliminary US patent application No. 63 / 664,568, filed on June 26, 2024, and the preliminary US patent application No. 63 / 665,198, filed on June 27, 2024, the entire contents of which are hereby incorporated by reference. background

[0002] Cordless, such as battery-powered, power tools generally have a motor designed to rotate in response to user input, such as pressing a trigger, to drive a tool bit. A motor subjected to excessive or prolonged use can, in some cases, overheat, potentially damaging the motor and its mechanical components. Some power tools have thermal protection devices that attempt to prevent motor overheating by shutting off the motor once a predetermined temperature is reached. overview

[0003] Some embodiments provide a power-driven tool comprising a motor, an inverter that drives the motor, a sensor that detects a variable indicating the motor's temperature, a trigger, a power source, and a controller that communicates with the inverter, sensor, trigger, and power source. The controller is configured to supply power from the power source to the inverter to drive the motor at a requested power level based on the trigger's deflection when it is pressed. The controller is further configured to reduce the requested power level at the inverter when the motor temperature reaches a first temperature threshold and to switch off the motor when the motor temperature reaches a second temperature threshold.

[0004] Some embodiments relate to a method for operating a power-driven tool. The method includes supplying power from a power source to an inverter to drive a motor at a requested power level based on the deflection of the trigger when it is pressed. The method further includes reducing the requested power level at the inverter when the motor temperature reaches a first temperature threshold, and switching off the motor when the motor temperature reaches a second temperature threshold.

[0005] Some embodiments provide a method for operating a power-driven tool. The method includes supplying power from a power source to an inverter to drive a motor at a requested power level based on the deflection of a trigger when it is pressed. The method also includes determining a minimum power level based on an input current to the motor, comparing the requested power level with the minimum power level, and reducing the requested power level for the inverter when the motor temperature reaches a first temperature threshold and the requested power level is greater than the minimum power level. Description of the drawings Fig. Figure 1 is a schematic view of a vivid, power-driven tool. Fig. Figure 2 is an isometric view of a representative rotary hammer. Fig. Figure 3 is a partial cross-sectional view of the rotary hammer made of Fig. 2. Fig. Figure 4 is a diagram showing temperature, current and motor speed over time, including actual measurements and predicted values ​​output from a thermal model. Fig. Figure 5 is another diagram showing temperature, current and motor speed over time, including actual measurements and predicted values ​​output by a thermal model. Fig. 6 is a clear method for operating a power-driven tool with motor protection. Fig. Figure 7 is another illustrative method for operating a power-driven tool with motor protection. Fig. Figure 8 is an exemplary relationship showing the average current in relation to minimum limits for reducing the power of an inverter for use with the method from Fig. 7 represents. Fig. Figure 9 is an example of a proportional-integral control loop for use with the method from Fig. 6 or Fig. 7. Fig. Figure 10 is another schematic view of a vivid power-driven tool. Detailed description

[0006] The following explanation is presented to enable a person skilled in the art to manufacture and use embodiments of the disclosed technology. In view of the teaching of this disclosure, various modifications of the illustrated embodiments will be readily apparent to a person skilled in the art, and the principles described herein can be applied to other embodiments and applications without departing from the embodiments of the disclosed technology. Thus, embodiments of the disclosed technology are not limited to those shown, but are intended to have the broadest possible scope that is compatible with the principles and features disclosed herein.

[0007] The following detailed description should be read with reference to the figures, in which identical elements in different figures have the same reference numerals. The figures, which are not necessarily to scale, show selected embodiments and are not intended to limit the scope of embodiments of the disclosed technology. Those skilled in the art will recognize that the examples given herein include many useful alternatives that lie within the scope of embodiments of the disclosed technology.

[0008] Before embodiments of the invention are explained in detail, it should be noted that the invention is not limited in its application to the design details and component arrangements set forth in the following description or illustrated in the following drawings. The invention may have other embodiments and be practiced or implemented in various ways. It should also be noted that the formulations and terms used here serve for descriptive purposes and are not to be understood as limiting. The use of "including," "comprising or with," or "featuring" and variants thereof are intended to encompass the elements listed below and their equivalents, as well as additional elements.Unless otherwise specified or limited, the terms "mounted," "connected," "supported," and "coupled," as well as variations thereof, are used in a broad sense and include both direct and indirect assemblies, connections, supports, and couplings. Furthermore, "connected" and "coupled" are not limited to physical or mechanical connections or couplings.

[0009] Generally, power tools are designed to shut down when a specified temperature is reached to prevent motor overheating and associated tool damage. Such shutdowns can be frustrating for users; therefore, it would be advantageous to extend the service life of such tools while simultaneously ensuring overheating protection. The present disclosure offers such an advantage by implementing improved motor protection for power tools. More specifically, the present disclosure presents systems and methods for reducing the power supplied to a motor inverter before the motor shuts down, in order to extend the tool's use without overheating.This means that the existing systems and procedures continue to operate the engine, but with reduced power in order to reduce heat output before the engine reaches a shutdown temperature.

[0010] In general, examples of the disclosed technology can be implemented in a wide variety of power tools, including, but not limited to, rotary hammers, demolition hammers, cutting tools, grinders, ratchets, sanders, drills, screwdrivers, staplers, saws, and dust extractors. In this context, it shows Fig. 1 a general schematic diagram of an illustrative power-driven tool, while Fig. 2 and Fig. Three additional details of a vivid rotary hammer are shown, it should be noted that all descriptions relating to Fig. 2 and Fig. 3 can also be applied to other power-driven tools.

[0011] Accordingly, it shows Fig. 1 A schematic diagram of an illustrative power-driven tool 10 according to some embodiments. As in Fig. As shown in Figure 1, the power-driven tool 10 can comprise a control unit 12, a drive unit 14 with a motor 16 and one or more sensors 18, a gear unit 20, an output such as a tool head or tool insert 22, a user input unit such as a trigger 24, and a power source such as a battery 26. Generally, the control unit 12 controls the drive unit 14, in particular the motor 16, as required in response to a user pressing the trigger 42. The motor 16 is powered by the battery 26, for example, a DC power source (although in some embodiments the motor 16 may instead be powered by an AC power source). The motor 16 is designed to generate torque under the control of the control unit 12, and the gear unit 20 is designed to receive the torque from the motor 16 and drive the output 22.For example, the torque from the motor 16 can be transmitted to the output 22 to move or rotate a tool insert. Furthermore, the control unit 12 can receive inputs from the sensors 18 to determine (directly or indirectly) an indication of the motor temperature and to further control the motor 16 based on this temperature indication, as described in more detail below. In some embodiments, the control unit 12 is part of the drive unit 14.

[0012] As a concrete example of a power-driven tool, we show Fig. 2 and Fig. 3. An example of a 30 mm rotary hammer. As in Fig. 2 and Fig. As shown in Figure 3, the rotary hammer 30 can have a housing 32, a handle 34, a removable second handle 36, an output chuck 38 for holding a tool insert 40, user input units including a trigger 42, a mode selector switch 44 and a forward / reverse switch 46, a battery receptacle 48 for holding a removable battery 50 and a dust extraction device 52.

[0013] According to Fig. 2. The housing 32 can be a gearbox housing 54, which contains a gearbox unit (like the one in Fig. 1 gear unit 20 shown), and a drive unit housing 56, which accommodates a drive unit 14 (in Fig. 3 shown) records, exhibit. As above in relation to Fig. As described in Figure 1, the drive unit 14 is configured to generate torque, and the gear unit 20 is configured to receive torque from the drive unit 14 and to move and / or rotate the tool insert 40. The specific output of the driven tool insert 40 can depend on user inputs, such as the mode selector switch 44 for selecting the output as a rotary hammer or a rotary hammer, the forward / reverse switch 46 for forward or reverse rotation, and the trigger 42 for starting, stopping, and speed control. The rotary hammer 30 can be powered by the battery 50, which is removable and housed in the battery compartment 48. Furthermore, the dust extraction device 52 can be permanently or detachably connected to the housing 32 and is designed to collect dust and other residues during operation.For example, the dust extraction device 52 can have a suction head 58 next to the tool insert 40, a suction hose 60 and an extraction housing 62.

[0014] In Fig. Figure 3 shows some internal components of the rotary hammer 30 (while other components are hidden for clarity and explanation). For example, it shows Fig. 3 the drive unit 14 with a motor 16, a printed circuit board assembly (PCBA) 13 (which, for example, has a control unit 12 mounted on it) and a sensor board 64. In addition, the rotary hammer 30 may have a fuse board 66, a capacitor board 68, a battery terminal 70, an auto-stop light-emitting diode (LED) 72 with an LED terminal 74 and additional LEDs 76 (or other light sources) next to the output chuck 38.

[0015] As in Fig. As shown in Figure 3, the PCBA 13 can be positioned within the drive unit 14 next to the battery receptacle 48 and have components configured to receive power from the battery 26 to control the operation of the motor 16. For example, the PCBA 13 can include the control unit 12, such as a microcontroller, a processor, or a dedicated integrated circuit (not shown), configured to perform control functions of the rotary hammer 30 and connected to an inverter (in Figure 3). Fig. 3 not shown), sensors (e.g. the one in Fig. to communicate with the sensors 18 shown in 1), the trigger 42, and the power source 50. In general, the terms "controller or control unit," "PCBA," "microcontroller," "microcontroller unit (MCU)," or "processor" can be used synonymously here. Furthermore, in some embodiments, such control functions can be stored in the memory of the PCBA 13 (e.g., as instructions on memory, such as a non-volatile, computer-readable medium) or, more precisely, in firmware, and can be executed by the controller 12.

[0016] The motor 16 can be a brushless DC motor (“BLDC”) and is configured to rotate in response to user inputs, such as actuation of the trigger 24, as controlled by the control unit 12. For example, the control unit 12 can supply power to an inverter of the motor 16 based on a trigger deflection. As a first example, a full (i.e., 100 percent) actuation of the trigger causes the control unit 12 to supply 100 percent of the power to the inverter, and a 50 percent actuation of the trigger causes the control unit 12 to supply 50 percent of the power to the inverter. However, in some embodiments, the power or requested power may not be directly proportional to the trigger deflection but may depend on it in some way. In another example, a full (i.e.,(100% activation of the trigger causes the control unit 12 to supply energy to the inverter to achieve a maximum (100%) rotational speed. In such embodiments, the control unit 12 can provide closed-loop speed control, where the percentage of the trigger deflection is converted into a desired rotational speed, which is then converted into a requested power or setpoint power calculated via a proportional-integral (PI) control loop. More precisely, in such implementations, the trigger deflection can be assigned to a percentage (e.g., via a spline).This assigned percentage can be multiplied by a speed range of the power-driven tool (where the speed range is, for example, equal to the maximum speed minus the minimum speed), and a target speed can be equal to the assigned percentage times the speed range plus the minimum speed. The target speed, along with the current speed, can then be fed into a PL control loop to generate a new requested power output to the inverter.

[0017] The control unit 12 can further control the motor 16 based on sensor inputs. More precisely, the rotary hammer 30 can, in some embodiments, have one or more sensors 18, such as a thermistor, rotor position sensors, and a current sensor. For example, the thermistor can provide the control unit 12 with temperature feedback indicating the temperature of the motor 16, such as the temperature of the motor windings, the temperature within the drive unit 14, or the temperature at another location near the motor 16. The position sensors, such as Hall sensors, can provide the control unit 12 with feedback indicating the motor speed (e.g., in revolutions per minute, rpm) based on the position of the motor rotor. The current sensors can provide feedback to the control unit 12 indicating the motor current.In some embodiments, one or more of these sensors 18 can be arranged in the drive unit 14 on the sensor board 64 (e.g., a Hall effect board). In other embodiments, however, the sensors 18 can be positioned at other locations, for example, directly on the windings of the motor 16 or at other locations.

[0018] In some embodiments, the motor temperature can be determined directly by a thermistor arranged on the windings of the motor 16. In other embodiments, for example, when the thermistor is arranged on the sensor board 64 in the drive unit 14, the motor temperature can be estimated using a thermal model that receives inputs from the thermistor, the position sensors, and the current sensors. In a specific example, the thermal model can be a machine learning-based algorithm that outputs a predicted motor temperature based on weighted inputs from the thermistor, the position sensors, and the current sensors.

[0019] For example, it shows Fig. 4. A diagram (78) of temperature, current, and motor speed over time illustrates how such a thermal model can track the actual motor winding temperatures. That is to say, Fig. Figure 4 shows an input current 80 (e.g., from a current sensor), a motor speed 82 (e.g., from Hall sensors), a reference temperature 84 (e.g., from a thermistor on the sensor board 64), a measured motor winding temperature 86, a measured stator temperature 88, a predicted motor winding temperature 90 (i.e., output of the thermal model using the input current, motor speed, and reference temperature), and a predicted stator temperature 92 (i.e., output of the thermal model using the input current, motor speed, and reference temperature). Furthermore, it shows Fig. Figure 5 shows another diagram (94) of the temperature, current, and motor speed over time during a motor overload event. In particular, in Fig. 5 to see that the motor 16 is so overloaded that the motor winding temperature, both the actual temperature 86 and the predicted temperature 90, reaches or exceeds a maximum winding temperature 96.

[0020] In some embodiments, the power-driven tool 10 (or the hammer drill 30) has a thermal protection mechanism that automatically shuts off the motor as soon as a maximum temperature threshold is reached (e.g., at or before the maximum winding temperature 96) to prevent overheating of the motor 16. According to some embodiments, an additional, improved thermal protection method may be provided to prevent the motor 16 from reaching the maximum temperature threshold or to extend the service life of the motor before the maximum temperature threshold is reached.

[0021] This means that, according to some embodiments, a power-driven tool 10 (such as a rotary hammer 30) can dynamically adjust the power of the motor 16 and, based on the motor temperature, override the user input unit in order to extend motor use before overheating. For example, the following illustrates Fig. 6 An example of a general method 100 for such an operation according to some embodiments. As in Fig. As shown in Figure 6, procedure 100 is started (step 102), the currently requested engine power is set (step 104), and it is determined whether the current temperature is greater than a first temperature threshold (step 106). If not, the procedure returns to step 104, and the currently requested engine power is maintained. If so, it is determined whether the current temperature is greater than a second temperature threshold (step 108). If so, the engine is switched off (step 110), and the procedure ends (step 112). If not in step 108, the currently requested engine power is reduced to set a new requested power in step 114, and procedure 100 returns to step 106. Procedure 100 continues through steps 106, 108, and 114 as long as the temperature remains between the first and second thresholds. If the temperature falls below the first threshold (i.e.,If YES in step 106), the procedure returns to step 104 and the requested power can again be set solely based on the trigger deflection. If the temperature rises above the second threshold (i.e., YES in step 108), the motor is switched off in step 110.

[0022] In some embodiments, the method 100 can be stored in memory as steps executed by the control unit 12. In some embodiments, this method 100 can be implemented as a control loop that is repeated once per time interval, for example, once per millisecond or another suitable time interval, while the power-driven tool 10 is switched on. For example, the method 100 can be repeated once per unit of time while a user presses the trigger 24. Instead of the control unit 12 operating the tool 30 solely on the basis of the trigger deflection until the second (e.g., maximum) temperature threshold is reached and interrupting operation as a thermal protection mechanism, the control unit 12 can, according to the method of Fig. 6. As the engine temperature increases, reduce the power (e.g. below the value that would be indicated by pressing the trigger) to keep the engine temperature below the second temperature threshold and to extend the usage before the engine shuts off.

[0023] Fig. Figure 7 shows another illustrative method 200 for such an operating mode according to some embodiments. In general, as in Fig. As shown in Figure 7, procedure 200 is started (step 202), the currently requested motor power is set (step 204), the motor current is averaged over a period of time (step 206), the average current is assigned to a minimum inverter power (step 208), and it is determined whether the requested motor power is greater than the minimum inverter power (step 210). If not, the currently requested motor power is maintained (step 212). If yes, it is determined whether the current temperature is greater than a temperature threshold (step 214). If not, the currently requested motor power is maintained (step 210). If yes, a proportional-integral control (PL control) is applied to calculate a new requested motor power (step 216).

[0024] In some embodiments, the method 200 can be stored in memory as steps to be executed by the control unit 12. In some embodiments, this method 200 can be executed as a control loop that is repeated once per time interval, for example, once per millisecond or another suitable time interval, while the power-driven tool 10 is switched on. For example, the method 200 can be repeated once per unit of time while a user presses the trigger 24. In other embodiments, the method 200 can be repeated once per unit of time while a user presses the trigger 24, but only if certain other criteria are met. Such other criteria may be, for example, a motor temperature threshold, a trigger threshold, a speed threshold, a specific mode selection, or other suitable criteria.

[0025] It should be more precisely referred to as procedure 200 in Fig. Reference is made to Figure 7; here, the control loop is started in step 202. Inputs to this control loop can include the motor temperature, the current, and the requested motor power. For example, the motor temperature can be estimated using a motor temperature model based on inputs from the thermistor on sensor board 64, the Hall sensors, and the current sensors, as described above. Alternatively, the motor temperature can be determined directly at the motor windings using a thermistor. In other embodiments, the motor temperature can be estimated or derived using other methods or sensors. The current can be determined from the current sensors (e.g., measured, amplified, and inverted current-sense voltage from a current sensor in the form of a current-sense resistor). The requested motor power can be determined based on the current deflection of the trigger.As explained above, the requested motor power can, for example, be a percentage of the power supplied to the inverter based on the trigger deflection, where the percentage of the trigger deflection is converted into a desired rotational speed, which is then converted into the requested motor power calculated via a PL loop. In some embodiments, the requested motor power can also be determined from the current trigger deflection using other methods.

[0026] In step 204, the current requested motor power is set. Initially, the current requested motor power can be based solely on the trigger deflection. However, the current requested motor power can be updated after step 216, as described in more detail below.

[0027] In step 206, the motor current is averaged over a period of time. For example, the current values ​​derived from the current sensor can be averaged over a specified number of samples and / or a specified period. In one specific example, the current can be averaged over a period of 100 milliseconds (ms); however, other time or sampling periods can be used in some implementations. Additionally, in some implementations, the current can be averaged twice. For example, instantaneous current values ​​can be captured by the current sensor and averaged over a specified number of samples, and these averaged values ​​can then be averaged over a period of 100 ms.

[0028] In step 208, the average current is assigned to a minimum inverter power. That is, a mapping or diagram can include a reduction in inverter power correlated with the current, so that the minimum power can be determined based on the average current. As mentioned above, the purpose of this procedure 200 may be to reduce the motor power to prevent motor overheating or to extend the operating time before overheating occurs. This mapping in step 208 can dynamically adjust the minimum inverter power based on the current output power of the power-driven tool 10. For example, the minimum power reduction can be set to prevent motor 16 from stalling.

[0029] As an example, Fig. 8 is an example of an assignment 118 for use in step 208. Fig. Figure 8 shows the average current in relation to the inverter's reduction limits. The value "maximum reduction of minimum power" 120 is the maximum power to which the inverter's power can be limited. The value "minimum reduction of power" 122 is the minimum power to which the inverter's power can be limited. The "minimum reduction current" 124 can be considered the lower current limit. The "maximum reduction current" 126 can be considered the upper current limit. Thus, for current values ​​below and up to the minimum reduction current 124, the minimum inverter power is set to the maximum value 120. For current values ​​at and above the maximum reduction current 126, the minimum inverter power is set to a minimum value of 122.For current values ​​between the minimum reduction current 124 and the maximum reduction current 126, the minimum inverter power is set according to an inverse linear relationship 128, as shown in . Fig. Figure 8 illustrates this. The values ​​for the maximum reduction of the minimum power (120), the reduction of the minimum power (122), the minimum reduction current (124), and the maximum reduction current (126) can be preset, for example, based on the tool type, size, and / or other factors. Accordingly, in step 208, the average current is entered, and a minimum power reduction is output based on the assignment.

[0030] Step 210 determines whether the requested motor power is greater than the minimum inverter power. That is, the output from step 204 is compared to the output from step 208. If the requested power is not greater than the minimum inverter power (i.e., "FALSE" in step 210), the procedure continues to step 212, where the requested power from step 204 is retained and motor 16 is driven with the requested power. The same requested power would be used again in step 204 if procedure 200 is repeated, for example, unless a user sets or releases trigger 24.

[0031] If the requested power is greater than the minimum inverter power (i.e., "TRUE" in step 210), the procedure proceeds to step 214, which determines whether the current temperature is higher than a temperature threshold. If not (i.e., "FALSE" in step 214), the current requested motor power is maintained (step 212). The temperature threshold might, for example, be a preset temperature below the maximum temperature threshold at which motor 16 shuts down. Therefore, if the current temperature is below the temperature threshold, there is no risk of motor 16 reaching the maximum temperature threshold, and there is no reason to reduce the motor power. However, if the output in step 214 is TRUE (i.e.,(If the current temperature is greater than a temperature threshold), a proportional-integral control loop (PL control loop) is applied in step 216 to calculate a new requested motor power to attempt to reduce or maintain the motor temperature below the maximum shutdown temperature threshold. This new requested motor power would then be used to drive motor 16 and would also be used in step 204 if procedure 200 is repeated, for example, if a user does not set the trigger 24 or does not release the trigger 24.

[0032] Fig. Figure 9 shows an example of a Pl loop 300 according to some embodiments described in step 216 of Fig. 7 or step 114 of Fig. 6 can be implemented. As in Fig. As shown in Figure 9, the PL loop 300 in step 302 involves subtracting the actual current from a current setpoint to determine a current error. In step 304, an integral of the current error is determined, and in step 306, the integral can be multiplied by an integral gain factor (e.g., a first predetermined gain value) to determine a first value (e.g., the integral component of the PI control output). In step 308, the current error can be multiplied by a proportional gain factor (e.g., a second predetermined gain value) to determine a second value (e.g., the proportional component of the PI control output). The first and second values ​​can then be added in step 310, and in step 312, an updated requested inverter power can be calculated based on the sum of the first and second values ​​(e.g., the proportional component of the PI control output).the sum of the proportional and integral components of the PI control output) and the minimum inverter power. For example, the updated requested power may be less than the current requested power output in step 204. Fig. 7, but greater than the minimum inverter power in step 208. In step 314, energy can be supplied to motor 16 based on the updated requested power. Additionally, the PI control loop 300 is described here in terms of current, but other variables can also be used in some embodiments. For example, temperature can be used in one implementation.

[0033] In light of the foregoing, Fig. 10. A schematic diagram of tool components according to some implementations. As in Fig. As shown in Figure 10, the control unit 12 can receive input information from sensors 18, including a thermistor 18A, Hall sensors 18B, and current sensors 18C. The control unit 12 can use the inputs from the sensors 18 to determine the temperature of the motor winding based on a thermal motor model 148, although in some implementations direct temperature sensing is possible (e.g., via a thermistor or other temperature sensor placed directly on the motor windings). The motor winding temperature, the current measured by sensor 18C, and the power requested by the trigger 42 can be input into a temperature PI control loop 150, which may include, for example, methods 100 and 300. The output of the temperature PI control loop 150 may be the updated requested motor power, e.g.,based solely on the deflection of the trigger or the trigger deflection and the PL loop 300, which can be input into a motor control unit 152. The motor control unit 152 can output gate logic control signals to a gate driver 154, which can output gate control signals to a motor inverter 156, which can apply the gate control signals to the motor 16 to control the motor 16.

[0034] Accordingly, in light of the above, motor 16 can be driven at a lower speed than required by the trigger deflection (e.g., a trigger deflection that would normally result in 75% power at the inverter may result in 50% power at the inverter due to the PI control loop) when a first temperature threshold (e.g., the first temperature threshold in step 106 in Fig. 6 or the temperature threshold in step 214 in Fig. 7) is achieved. Since the motor 16 is driven at a lower power, the motor temperature can be reduced. That is, methods 100, 200, 300 can attempt to reduce the power until the motor temperature stabilizes or falls below a specified temperature threshold, or until a minimum inverter power is reached at which the tool 10, 30 continues to operate at minimum power until the maximum temperature threshold (e.g., the second temperature threshold in step 108 in Fig. 6) is reached, at which the thermal protection mechanism stops the motor 16. For example, the control unit 12 can be in the following at any time during tool operation according to methods 100, 200, 300. Fig. 6, Fig. 7 and Fig. 9. If the motor temperature reaches a second temperature threshold, e.g., the maximum temperature threshold, the motor 16 is automatically switched off according to the thermal protection mechanism. However, the methods 100, 200, and 300 described herein can reduce the power supplied to the inverter before switching off the motor when the first temperature threshold is reached, in order to achieve thermal recovery and extend motor use before a necessary shutdown.

[0035] In some embodiments, this reduction in motor power according to the Pl loop 300 can be perceived by the user, thus providing feedback to the user that the tool 10 is attempting to continue operation despite the increasing motor temperature. In further embodiments, additional feedback can be given to the user at this time. For example, if step 114 in Fig. 6 or step 216 in Fig. When 7 is reached, the control unit 12 can instruct one or more LEDs 72, 76 to light up and / or flash.

[0036] Those skilled in the art will recognize that the invention, although previously described in connection with certain embodiments and examples, is not necessarily limited thereto, and that numerous other embodiments, examples, uses, modifications, and variations from those embodiments, examples, and uses are intended to be covered by the appended claims. The entire disclosure of all patents and publications cited herein is incorporated by reference as if each of these patents or publications were individually incorporated herein by reference. Various features and advantages of the invention are set forth in the following claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 664,568

[0001] US 63 / 665,198

[0001]

Claims

[1] A power-operated tool, with: an engine; an inverter that controls the motor; a sensor designed to detect a variable indicating the engine temperature; a trigger; an energy source; and a control unit that is connected to the inverter, the sensor, the trigger and the energy source, wherein the control unit is designed to: Supplying energy from the energy source to the inverter to control the motor at a requested power level based on a deflection of the trigger when the trigger is engaged, Reducing the requested power level for the inverter when the motor temperature reaches an initial temperature threshold, and The engine shuts off when the engine temperature reaches a second temperature threshold. [2] The power-driven tool according to claim 1, wherein the control unit is further configured to maintain the requested power level for the inverter when the first temperature threshold is reached, provided that the requested power level is below a minimum power level. [3] The power-driven tool according to claim 2, wherein the control unit is further configured to determine the minimum power level based on an average input current to the motor. [4] The power-driven tool according to claim 3, wherein the control unit is further configured to determine the average input current to the motor based on the input from the sensor. [5] The power-driven tool according to claim 1, wherein the control unit is further configured to determine the motor temperature on the basis of a thermal model calculated using inputs from the sensor. [6] The power-driven tool according to claim 5, wherein the sensor comprises a thermistor arranged in a drive unit accommodating the motor, a current-sensing resistor measuring the input current to the motor, and a Hall sensor determining the speed of the motor. [7] The power-driven tool according to claim 1, wherein the sensor is a thermistor arranged on a winding of the motor and the control unit is further configured to determine the motor temperature based on the input from the sensor. [8] The power-driven tool according to claim 1, wherein the control unit is configured to reduce the requested power level using a proportional-integral control loop. [9] The power-driven tool according to claim 8, wherein the proportional-integral control loop uses a motor current as an input variable. [10] The power-driven tool according to claim 8, wherein the proportional-integral control loop uses a motor temperature as an input variable. [11] A method for operating a power-driven tool, the method comprising: Supplying energy from a power source to an inverter to control a motor at a requested power level based on the deflection of a trigger when the trigger is pressed; Reducing the requested power level to the inverter when the motor temperature reaches a first temperature threshold; and The engine shuts off when the engine temperature reaches a second temperature threshold. [12] The method according to claim 11, which further comprises: maintaining the requested power level to the inverter when the first temperature threshold is reached, if the requested power level is below a minimum power level. [13] The method according to claim 12, which further comprises: determining the minimum power level based on an average input current to the motor. [14] The method according to claim 13, wherein determining the minimum power level based on the average input current to the motor comprises using an assignment of average input current to minimum power level according to a type of power-driven tool. [15] The method according to claim 14, wherein the assignment limits the minimum power level between a minimum value and a maximum value. [16] The method according to claim 14, wherein the assignment provides an inverse relationship between the average input current and the minimum efficiency. [17] The method according to claim 11, which further comprises determining the motor temperature on the basis of a thermal model calculated using inputs from a thermistor located in a drive unit accommodating the motor, a current-sensing resistor measuring the input current to the motor, and a Hall sensor determining a speed of the motor. [18] The method according to claim 11, which further comprises obtaining the motor temperature from a thermistor located on a motor winding. [19] The method according to claim 11, wherein reducing the requested power level to the inverter comprises reducing the requested power level to the inverter using a proportional-integral control loop. [20] A method for operating a power-driven tool, the method comprising: Supplying energy from a power source to an inverter in order to control a motor at a requested power level based on the deflection of a trigger when the trigger is pressed; Determining a minimum power level based on an input current to the motor; Comparing the requested power level with the minimum power level; and Reducing the requested power level for the inverter when the motor temperature reaches a first temperature threshold and the requested power level is higher than the minimum power level.

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