Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
  • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
  • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
  • B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers
  • B25B23/1475—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers for impact wrenches or screwdrivers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
  • B25B21/02—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose with means for imparting impact to screwdriver blade or nut socket
  • B25B21/026—Impact clutches

Definitions

• the invention relates to a method for detecting a first operating state of a handheld power tool, and a handheld power tool set up to carry out the method.
• An impact wrench of this type includes, for example, a structure in which an impact force in a rotating direction is transmitted to a screw element by a rotation force of a hammer.
• the impact wrench which has this structure, includes a motor, a hammer to be driven by the motor, an am boss which is hit by the hammer, and a tool.
• the motor built into a housing is driven, the hammer being driven by the motor, the anvil in turn being struck by the rotating hammer and an impact force being applied to the tool, with two different operating states, namely "no impact operation” and " Schlag too "can be distinguished.
• EP 2 599 589 B1 also discloses an impact wrench with a motor, with a hammer and a rotational speed detection unit, where the hammer is driven by the motor.
• Knowledge of the current operating status is required for the provision of intelligent tool functions.
• An identification of the same is carried out in the prior art, for example, by monitoring the operating variables of the electric motor, such as speed and electric motor current.
• the operating parameters are examined to determine whether certain limit values and / or threshold values are reached.
• Corresponding evaluation methods work with absolute threshold values and / or signal gradients.
• the disadvantage here is that a fixed limit value and / or threshold value can practically only be perfectly set for one application. As soon as the application changes, the associated current or speed values or their temporal progressions also change, and impact detection based on the set limit value and / or threshold value or their temporal progression no longer works.
• additional sensors such as acceleration sensors, are used to infer the operating mode from the vibration states of the tool.
• Disadvantages of this method are additional costs for the sensors as well as losses in the robustness of the handheld power tool, since the number of built-in components and electrical connections increases compared to handheld power tools without these sensors.
• the object of the invention is to provide a method for recognizing operating states that is improved compared to the prior art, which at least partially eliminates the above-mentioned disadvantages, or at least to provide an alternative to the prior art.
• Another task be is to specify a corresponding hand tool.
• a method for detecting a first operating state of a handheld power tool comprising the following steps:
• step S2 Decide whether the first operating state is present, the decision at least partially depending on whether the state-typical model signal shape is identified in the signal of the operating variable in step S2.
• the method according to the invention enables the detection of the first operating state independently of at least one target speed of the electric motor, at least one start-up characteristic of the electric motor and / or at least one state of charge of an energy supply, in particular a battery, of the handheld power tool.
• the method according to the invention enables the detection of the first operating state for applications in which a loose fastening element is screwed into a fastening carrier, as well as in which a fixed, in particular at least partially screwed in, fastening element is screwed into a fastening carrier.
• the applications can include both hard and soft screwing cases, a typical application case being, for example, a self-tapping screw connection or a Holzver screw connection.
• the “loose fastening element” is to be understood as a fastening element that is essentially not screwed into the fastening carrier and that is intended to be screwed into the fastening carrier.
• the “fixed fastening element” is to be understood as a fastening element that is at least partially screwed into the fastening support or is essentially screwed entirely into the fastening support.
• the at least one state-typical model signal shape can be determined, the state-typical model signal shape being assigned to the first operating state.
• a limit and / or threshold value for an existing agreement or an existing error from the signal of the operating variable to the state-typical model signal form can represent an adjustable variable for applications for successful shock detection.
• the state-typical model signal shape is stored or stored inside the device, alternatively and / or additionally made available to the handheld power tool, in particular made available by an external data device.
• “determine” should in particular include measuring or recording, with “recording” being understood in the sense of measuring and storing, and “determining” should also include a possible signal processing of a measured signal.
• decide should also be understood as recognizing or detecting, with an unambiguous assignment being achieved.
• Identify is to be understood as recognizing a partial match with a pattern, which can be made possible, for example, by fitting a signal to the pattern, a Fourier analysis or the like.
• the “partial agreement” should be understood to mean that the fitting has an error that is less than a predefined threshold, in particular less than 30%, in particular less than 20%.
• the signal of the company size should be understood here as a time sequence of measured values.
• the signal of the operating variable can also be a frequency spectrum.
• the signal of the operating variable can also be post-processed, such as, for example, smoothed, filtered, fitted and the like.
• the state-typical model signal shape is an oscillation curve around a mean value, in particular an essentially trigonometric oscillation curve.
• the state-typical model signal form preferably represents an ideal percussion operation of the hammer on the anvil of the rotary percussion mechanism.
• the operating variable is a speed of the electric motor or an operating variable that correlates with the speed.
• the rigid transmission ratio of the electric motor to the hammer mechanism results in, for example, a direct relationship between the motor speed and the hammer frequency.
• Another conceivable operating variable that correlates with the speed is the motor current.
• a motor voltage, a Hall signal from the motor, a battery current or a battery voltage are also conceivable as the operating variable of the electric motor, with an acceleration of the electric motor, an acceleration of a tool holder or a sound signal from an impact mechanism of the hand machine tool also being conceivable as the operating variable.
• the signal of the operating variable is recorded in method step S1 as a time curve of measured values of the operating variable, or recorded as measured values of the operating variable as a variable of the electric motor that correlates with the time curve, for example an acceleration, a jolt, in particular a higher order, a power , an energy, an angle of rotation of the electric motor, an angle of rotation of the tool holder or a frequency.
• the signal of the operating variable is recorded in method step S1 as a time course of measured values of the operating variable, with a transformation of the time curve of the measured values of the operating variable into a curve of the measured values of the operating variable in a step S1a following method step S1 due to the rigid gear ratio of the transmission takes place as a variable of the electric motor that correlates with the time course.
• the signal of the operating variable is stored as a sequence of measured values in a memory, preferably a ring memory, in particular the handheld power tool.
• the measured values are segmented in such a way that the signal of the operating variable always includes a predetermined number of measured values.
• the signal of the operating variable is compared in method step S2 using one of the comparison methods comprising at least one frequency-based comparison method and / or a comparative comparison method, the comparison method comparing the signal of the operating variable with the state-typical model signal shape, whether at least a predetermined threshold value is fulfilled.
• the preset threshold value can be preset at the factory or can be set by a user.
• the frequency-based comparison method comprises at least the bandpass filtering and / or the frequency analysis, the predetermined threshold value being at least 85%, in particular 90%, especially 95%, of a predetermined limit value.
• the recorded signal of the operating variable is filtered via a bandpass whose pass band matches the state-specific model signal shape.
• a corresponding amplitude in the resulting signal is to be expected in the first operating state, in particular in impact operation.
• the predefined threshold value of the bandpass filtering can therefore be at least 85%, in particular 90%, in particular 95%, of the corresponding amplitude in the first operating mode, in particular in impact mode.
• the predefined limit value can be the corresponding amplitude in the resulting signal of an ideal first operating state, in particular an ideal impact operation.
• the predefined, state-typical model signal form for example a frequency spectrum of the first operating state, in particular a field operation
• the predefined, state-typical model signal form for example a frequency spectrum of the first operating state, in particular a field operation
• the recorded signals of the operating variable a corresponding amplitude of the first operating state, in particular the impact mode, is to be expected.
• the predetermined threshold value of the frequency analysis can be at least 85%, in particular 90%, very particularly 95%, of the corresponding
• the predetermined limit value can be the corresponding amplitude in the recorded signals of an ideal first operating state, in particular an ideal impact operation. Appropriate segmentation of the recorded signal of the farm size may be necessary.
• the decision can be made at least partially by means of the frequency-based comparison method, in particular bandpass filtering and / or frequency analysis, as to whether the first operating state was identified in the signal of the operating variable.
• the comparative comparison method comprises at least the parameter estimation and / or the cross-correlation, the predefined threshold value being at least 50% of a match between the signal of the operating variable and the model signal shape typical of the state.
• the measured signal of the operating variable can be compared with the state-typical model signal form using the comparative comparison method.
• the measured signal of the operating variable is determined in such a way that it has essentially the same finite signal length as that of the model signal shape typical of the state.
• the comparison of the state-typical model signal shape with the measured signal of the operating variable can be output as a, in particular discrete or continuous, signal of a finite length. Depending on a degree of correspondence or a deviation in the comparison, a result can be output as to whether the first operational status, in particular impact operation, is present. If the measured If the signal of the operating variable agrees at least 50% with the state-typical model signal shape, the first operating state, in particular the impact mode, may be present.
• the comparative method can output a degree of deviation from one another as a result of the comparison by comparing the measured signal of the operating variable with the model signal shape typical of the state.
• the deviation of at least 50% from one another can be a criterion for the existence of the first operating state, in particular impact operation.
• a comparison between the previously established, state-typical model signal shape and the signal of the operating variable can easily be made.
• estimated parameters of the state-typical model signal form can be identified in order to match the state-typical model signal form to the measured signal of the operating variables.
• a result for the presence of the first operating state, in particular the field operation can be determined.
• the result of the comparison can then be assessed as to whether the predefined threshold value has been reached. This assessment can either be a determination of the quality of the estimated parameters or the deviation between the defined, state-typical model signal form and the recorded signal of the operating variable.
• method step S2 contains a step S2a of a quality determination of the identification of the state-typical model signal shape in the signal of the operating variable, wherein in method step S3 the decision as to whether the first operating state is present is made at least partially on the basis of the quality determination.
• a goodness of fit of the estimated parameters can be determined as a measure of the quality determination.
• the decision can be made at least partially by means of the quality determination, in particular the measure of the quality, as to whether the first operating state was identified in the signal of the operating variable.
• a deviation determination of the identification of the state-typical model signal shape and the signal of the operating variable can include.
• the deviation of the estimated parameters of the state-typical model signal form from the measured signal of the operating variable can be, for example, 70%, in particular 60%, in particular 50%.
• the decision as to whether the first operating state is present is made at least partially on the basis of the deviation determination.
• the decision as to whether the first operating state is present can be made with the predefined threshold value of at least 50% correspondence between the measured signal of the operating variable and the state-typical model signal form.
• a comparison can be made between the predefined, state-typical model signal form and the measured signal of the operating variable.
• the predefined, state-typical model signal form can be correlated with the measured signal of the company variable.
• a degree of correspondence between the two signals can be determined.
• the degree of correspondence can be, for example, 40%, in particular 50%, very particularly 60%.
• the decision as to whether the first operating state is present can be made at least partially on the basis of the cross-correlation of the state-typical model signal shape with the measured signal of the operating variable.
• the decision can be made at least partially on the basis of the predetermined threshold value of at least 50% correspondence between the measured signal of the operating variable and the state-typical model signal shape.
• the first operating state is determined on the basis of less than ten impacts of an impact mechanism of the handheld power tool, in particular less than ten impact oscillation periods of the electric motor, preferably less than six impacts of an impact mechanism of the handheld power tool, in particular less than six impact oscillation periods of the electric motor, very preferably less than four impacts of an impact mechanism, in particular less than four impact oscillation periods of the electric motor, identified.
• an axial, radial, tangential and / o the circumferential impact of a hammer, in particular a hammer, on a hammer, in particular an Am boss is to be understood as a blow of the hammer mechanism.
• the impact oscillation period of the electric motor is correlated with the operating size of the electric motor.
• An impact oscillation period of the electric motor can be determined on the basis of operating variable fluctuations during the first operating state in the signal of the operating variable.
• the identification of the impacts of the impact mechanism of the handheld power tool, in particular the impact oscillation periods of the electric motor, can be achieved, for example, by using a Fas-Fitting algorithm by means of which an evaluation of the impact detection within less than 100 ms, in particular less than 60 ms , in particular less than 40 ms, can be made possible.
• the inventive method enables the detection of the first operating state essentially for all of the above-mentioned applications and a screw connection for loose as well as fixed fastening elements in the fastening carrier.
• the hand-held power tool is advantageously an impact wrench, in particular an impact screwdriver, and the first operating state is an impact operation, in particular an impact operation.
• the present invention largely eliminates the need for more complex signal processing methods such as e.g. Filters, signal loopbacks, system models (static as well as adaptive) and signal tracking are possible.
• these methods allow an even faster identification of the impact operation or the work progress, which can cause an even faster reaction of the tool. This applies in particular to the number of previous blows from the start of the hammer mechanism up to identification and also in special operating situations such as the start-up phase of the drive motor. There are also no functional restrictions of the tool such as a reduction in the maximum drive speed.
• a further object of the invention is a handheld power tool, having an electric motor, a measured value sensor for an operating variable of the electric motor, and a motor controller, the handheld power tool being advantageously an impact wrench, in particular a rotary impact wrench, and the first operating state being an impact operation, in particular a rotary impact operation .
• the electric motor sets an input spindle in rotation, an output spindle being connected to a tool holder.
• An anvil is rotatably connected to the output spindle and a hammer is connected to the input spindle in such a way that it executes an intermittent movement in the axial direction of the input spindle and an intermittent rotational movement around the input spindle as a result of the rotational movement of the input spindle, with the hammer on in this way strikes the anvil intermittently and thus emits an impact and a rotary impulse to the anvil and thus to the output spindle.
• a first sensor transmits a first signal to the control unit, for example to determine an engine rotation angle.
• a second sensor can transmit a second signal to the control unit to determine an engine speed.
• the control unit is advantageously designed to carry out a method according to one of Claims 1 to 14.
• the handheld power tool is a battery-powered handheld power tool, in particular a battery-powered rotary impact wrench.
• the handheld power tool is a cordless screwdriver, a drill, a percussion drill or a hammer drill, it being possible to use a drill, a drill bit or various bit attachments as the tool.
• the craft tractor according to the invention is designed in particular as an impact screwdriver tool, with a higher peak torque for a screwing in or unscrewing a screw or a screw nut being generated by the impulsive release of the engine energy.
• the transfer of electrical energy is to be understood in particular as meaning that the handheld power tool transfers energy to the body via a battery and / or via a power cable connection.
• the screwing tool can be designed to be flexible in the direction of rotation. In this way, the proposed method can be used both for screwing in and for unscrewing a screw or a screw nut.
• Fig. 1 is a schematic representation of an electrical craft
• 2 (a) shows a schematic representation of a signal of an operating variable of a handheld power tool with a loose fastening element
• 2 (b) shows a schematic representation of a signal of an operating variable of a handheld power tool with a fixed fastening element
• 3 is a schematic representation of two different recordings of the signal of the operating variable
• FIG. 5 shows a joint illustration of a signal of an operating variable and a state-typical model signal for bandpass filtering
• FIG. 6 shows a joint illustration of a signal of an operating variable and a state-typical model signal for the frequency analysis
• FIG. 7 shows a joint illustration of a signal of an operating variable and a state-typical model signal for parameter estimation
• FIG. 8 shows a joint illustration of a signal of an operating variable and a state-typical model signal for the cross-correlation.
• FIG. 1 shows a handheld power tool 100 according to the invention which has a housing 105 with a handle 115.
• the handheld power tool 100 can be mechanically and electrically connected to a battery pack 190 for mains-independent power supply.
• the hand power tool 100 is exemplified as a cordless rotary impact screwdriver. It is pointed out, however, that the present invention is not limited to cordless impact wrenches, but in principle can be used in handheld power tools 100 in which the detection of operating states is necessary, such as impact drills.
• An electric motor 180 which is supplied with power by the battery pack 190, and a transmission 170 are arranged in the housing 105.
• the electric motor 180 is connected to an input spindle via the transmission 170.
• a control unit 370 is arranged within the housing 105 in the area of the battery pack 190, which is used to control and / or regulate the electric motor 180 and the gearbox 170, for example by means of a set engine speed n, a selected angular momentum, a desired gearbox gear x or the like acts on this.
• the electric motor 180 can be operated, for example, via a manual switch 195, i. H. can be switched on and off and can be any type of motor, for example an electronically commutated motor or a direct current motor.
• the electric motor 180 can be electronically controlled or regulated in such a way that both a reversing operation and specifications with regard to the desired motor speed n and the desired angular momentum can be implemented.
• the mode of operation and the structure of a suitable electric motor are sufficiently known from the prior art, so that a detailed description is dispensed with here for the sake of brevity.
• a tool holder 140 is rotatably mounted in the housing 105 via an input spindle and an output spindle.
• the tool holder 140 serves to hold a tool and can be molded directly onto the output spindle or connected to it in the form of an attachment.
• the control unit 370 is connected to a power source and is designed in such a way that it can electronically control or regulate the electric motor 180 by means of various power signals.
• the different current signals ensure different rotational impulses of the electric motor 180, the current signals being passed to the electric motor 180 via a control line.
• the power source can be configured, for example, as a battery or, as in the exemplary embodiment provided, as a battery pack 190 or as a mains connection.
• FIG. 2 shows an example signal of an operating variable 200 of an electric motor 180 of a rotary impact wrench, as it occurs in this way or in a similar form when a rotary impact wrench is used as intended. While the following remarks refer to an impact wrench be, they apply accordingly within the scope of the invention to other hand machine tools 100 such as impact drills.
• the time is plotted as a reference variable on the abscissa x.
• a variable correlated with time is plotted as a reference variable, such as the angle of rotation of the tool holder 140 or the angle of rotation of the electric motor 180.
• the engine speed n present at any point in time is plotted on the ordinate f (x) in the figure .
• f (x) represents a signal of the motor current, for example.
• the motor speed and motor current are operating variables which, in the case of hand tool machines 100, are usually recorded by a control unit 370 without any additional effort.
• the determination of the signal of an operating variable 200 of the electric motor 180 is identified as method step S1 in FIG. 4, which shows a schematic flow chart of a method according to the invention.
• a user of the hand machine tool 100 can select based on which operating variable the inventive method is to be carried out.
• Fig. 2 (a) an application of a loose fastening element, for example a screw, in a mounting bracket, such as a wooden board, is shown.
• the signal comprises a first range 310, which is characterized by a monotonous increase in the engine speed, as well as a range of comparatively constant engine speed, which can also be referred to as a plateau.
• the intersection between the x abscissa and the ordinate f (x) in Figure 2 (a) corresponds to the start of the impact wrench during the screwing process.
• the impact wrench works in the operating state of screwing without impact.
• the impact wrench works in a rotary impact mode.
• the rotary percussion mode is characterized by an oscillating profile of the signal of the operating variable 200, wherein the form of the oscillation can be, for example, trigonometric or oscillating in some other way.
• the oscillation has a course that can be described as a modified trigonometric function, the upper half-wave of the oscillation having a pointed or tooth-like shape.
• This characteristic form of the signal of company size 200 in impact wrench operation is created by the pulling up and free running of the hammer mechanism and the system chain between the impact mechanism and the electric motor 180, among other things. of gearbox 170.
• the qualitative signal form of the impact operation is known in principle due to the inherent properties of the impact wrench.
• at least one state-typical model signal shape 240 is determined in a step SO, where the state-typical model signal shape 240 corresponds to the first operating state, in the example of FIG. 2 (a) that is the impact screwdriving operation in the second area 320, assigned.
• the state-typical model signal form 240 contains typical features for the first operating state, such as the presence of an oscillation curve, oscillation frequencies or amplitudes, or individual signal sequences in continuous, quasi-continuous or discrete form.
• the first operating state to be detected can be characterized by signal forms other than oscillations, for example by discontinuities or growth rates in the function f (x).
• the state-typical model signal shape is characterized by these parameters instead of vibrations.
• Fig. 2 (b) is an application of a fixed fastening element, for example a screw, in a fastening support, for example a wooden board, shown.
• “fixed” means that the fastening element is at least partially screwed into the fastening support and an interrupted screwing process is to be continued.
• the numerals and designations of the first and second areas 310, 320 are as in FIG. 2 (a).
• the difference between the application in FIG. 2 (b) and FIG. 2 (a) is that after a short start-up phase with the monotonically increasing speed, the rotary percussion operation already begins during the monotonically increasing speed.
• Fig. 2 (b) it can be seen that there is essentially no plateau with the comparatively constant speed.
• the state-typical model signal shape 240 can be established in method step SO.
• the state-typical model signal form 240 can be stored, calculated or stored in the device.
• the model signal shape typical for the state can alternatively and / or additionally be provided to the hand-held power tool 100, for example from an external data device.
• the signal of the operating variable of the electric motor 180 is compared with the state-typical model signal shape 240.
• the “compare” feature is to be interpreted broadly in the context of the present invention and in the sense of a signal analysis, so that a result of the comparison can in particular also be a partial or gray correspondence of the signal of the operating variable 200 of the electric motor 180 with the state-typical model signal form 240
• the degree of correspondence between the two signals can be determined by various methods which will be mentioned later.
• a method step S3 of the method according to the invention the decision as to whether the first operating state is present is made at least in part on the basis of the result of the comparison.
• the degree of correspondence is a factory or user-adjustable parameter for setting a sensitivity of the detection of the first operating state.
• the method steps S1, S2 and S3 are carried out repeatedly during the operation of a handheld power tool 100 in order to monitor the operation for the presence of the first operating state.
• the determined signal of the operating variable 200 can be segmented in method step S1, so that method steps S2 and S3 are carried out on signal segments, preferably always of the same, fixed length.
• the signal of the operating variable 200 can be stored as a sequence of measured values in a memory, preferably a ring memory.
• the handheld power tool 100 includes the memory, preferably the ring memory.
• the signal of the operating variable 200 is determined as a time curve of measured values of the operating variable, or as measured values of the operating variable as a variable of the electric motor 180 that correlates with the time curve the measured values can be discrete, quasi-continuous or continuous.
• One embodiment provides that the signal of the farm variable 200 is recorded in method step S1 as a time curve of measured values of the farm variable and in a method step S1a following method step S1 a transformation of the time curve of the measured values of the farm variable into a curve of the measured values of the farm variable takes place as a variable of the electric motor 180 that correlates with the course of time, such as the angle of rotation of the tool holder 140 or the angle of rotation of the motor.
• FIG. 3a shows signals f (x) of an operating variable 200 over an abscissa x, in this case over time t.
• the operating variable can be an engine speed or a parameter that correlates with the engine speed.
• the figure contains two signal curves for operating size 200 in the first operating mode, i.e. in the case of an impact wrench in impact wrench mode.
• the signal comprises a wavelength of an idealized sinusoidal waveform, the signal with a shorter wavelength, T 1 with a higher beat frequency, and the signal with a longer wavelength, T2, with a lower beat frequency.
• Both signals can be generated with the same handheld power tool 100 at different engine speeds and are, among other things, dependent on the rotational speed the user requests from the handheld power tool 100 via the operating switch.
• the parameter “wavelength” is to be used to define the typical state model signal shape 240
• at least two different wavelengths T1 and T2 would have to be stored as possible parts of the typical state model signal shape so that the comparison of the signal of the operating variable 200 with the state-typical model signal form 240 leads to the result “agreement” in both cases. Since the motor speed can change over time in general and to a large extent, this means that the searched wavelength also varies and the methods for recognizing this beat frequency would have to be adjusted accordingly.
• the time values on the abscissa are therefore transformed into values that correlate with the time values, such as acceleration values, higher-order jerk values, power values, energy values, frequency values, angle of rotation values of the tool holder 140 or angle of rotation values of the electric motor 180.
• the time values such as acceleration values, higher-order jerk values, power values, energy values, frequency values, angle of rotation values of the tool holder 140 or angle of rotation values of the electric motor 180.
• the state-specific model signal form 240 valid for all speeds by a single parameter of the wavelength via the time-correlating variable, such as the angle of rotation of the tool holder 140 or the motor angle of rotation, can be set.
• the comparison of the signal of the operating variable 200 takes place in method step S2 with a comparison method, the comparison method comprising at least one frequency-based comparison method and / or a comparative comparison method.
• the comparison method compares the signal of the operating variable 200 with the model signal shape 240 typical of the state, as to whether at least one predetermined threshold value is met.
• the frequency-based comparison method includes at least bandpass filtering and / or frequency analysis.
• the comparative comparison method comprises at least the parameter estimation and / or the cross-correlation. The frequency-based and comparative comparison methods are described in more detail below.
• the input signal transformed to a variable correlating with time, if necessary as described, is filtered via a bandpass whose pass band represents the predetermined threshold value.
• the pass band results from the state-specific model signal form 240. It is also conceivable that the pass band corresponds to a frequency defined in connection with the state-typical model signal form 240. In the event that amplitudes of this frequency exceed a predetermined limit value, as is the case in the first operating state, the comparison in method step S2 then leads to the result that the signal of the operating variable 200 equals the state-typical model signal form 240, and that the first operating state is thus executed.
• an amplitude limit value can in this embodiment can be interpreted as a method step S2a following method step S2 of a quality determination of the correspondence of the state-typical model signal shape 240 with the signal of the operating variable 200, on the basis of which it is decided in method step S3 whether the first operating state is present or not.
• the signal of the operational variable 200 is transformed from a time domain into the frequency domain with appropriate weighting of the frequencies on the basis of the frequency analysis, for example the fast Fourier transformation (FFT),
• FFT fast Fourier transformation
• Frequency analysis in this form is well known as a mathematical tool for signal analysis from many areas of technology and is used, among other things, to approximate measured signals as series developments of weighted periodic harmonic functions of different wavelengths.
• the weighting factors indicate whether and to what extent the corresponding harmonic functions of a certain wavelength are present in the examined signal.
• the frequency analysis can be used to determine whether and with what amplitude the frequency assigned to the state-typical model signal shape 240 is present in the signal of the operating variable 200.
• a limit value of the amplitude can be established, which is a measure of the degree of agreement of the signal of the operating variable 200 with the state-specific model signal form 240. If the amplitude of the frequency assigned to the state-typical model signal shape 240 in the signal of the operating variable 200 exceeds this limit value, it is determined in method step S3 that the first operating state is present.
• the signal of the operating variable 200 is compared with the state-typical model signal form 240 in order to find out whether the measured signal of the operating variable 200 has at least a 50% agreement with the state-typical model waveform 240 and so that the specified threshold is reached. It is also conceivable that the signal of the operating variable 200 is compared with the state-typical model signal shape 240 in order to determine a deviation between the two signals.
• the measured signal of the operating variables 200 is compared with the state-typical model signal shape 240, estimated parameters being identified for the state-typical model signal shape 240.
• estimated parameters it is possible to determine a degree of correspondence between the measured signal of the operating variables 200 and the state-typical model signal form 240, as to whether the first operating state is present.
• the parameter estimation is based on the compensation calculation, which is a mathematical optimization method known to the person skilled in the art.
• the mathematical optimization method enables the state-typical model signal form 240 to be matched to a series of measurement data of the signal of the operating variable 200.
• the decision as to whether the first operating state is present can be made as a function of the degree of correspondence between the estimated parameters of the model signal shape 240 typical for the state and the measured signal of the operating variable 200.
• a measure of a deviation between the estimated parameters of the state-typical model signal shape 240 and the measured signal of the operating variable 200 can also be determined.
• a deviation determination is carried out in method step S2 following method step S2a. If the deviation from the state-typical model signal shape 240 to the measured signal of the operating variable of 70% is determined, the decision can be made as to whether the first operating state was identified in the signal of the operating variable and whether the first operating state is present.
• a quality determination for the estimated parameters is carried out in a method step S2a following method step S2.
• values for a quality between 0 and 1 are determined, with the rule that a higher value represents a higher correspondence between the state-typical model signal form 240 and the signal of the operating variable 200.
• the decision as to whether the first operating state is present is made in the preferred embodiment in method step S3 at least partially on the basis of the condition that the value of the quality is in a range of 50%.
• the method of cross-correlation is used as the comparative comparison method in method step S2.
• the cross-correlation method is known per se to the person skilled in the art.
• the state-typical model signal form 240 is correlated with the measured signal of the operating variable 200.
• the result of the cross-correlation is again a signal sequence with an added signal length from a length of the signal of the operating variable 200 and the model signal shape 240 typical for the state, which represents the similarity of the time-shifted input signals.
• the maximum of this output sequence represents the point in time of the greatest correspondence between the two signals, i.e. the signal of the operating variable 200 and the state-typical model signal form 240, and is therefore also a measure of the correlation itself, which in this embodiment is used in method step S3 as a decision criterion for the existence of the first operating state.
• an essential difference to parameter estimation is that any state-typical model signal shapes can be used for the cross-correlation, while in the parameter estimation the state-typical model signal shape 240 must be able to be represented by parameterizable mathematical functions.
• FIG. 5 shows the measured signal of the operating variable 200 for the case that bandpass filtering is used as the frequency-based comparison method.
• the time or a variable correlating with time is plotted as the abscissa x.
• FIG. 5a shows the measured signal of the operating variable, an input signal of the bandpass filtering, the hand-held power tool 100 being operated in screwdriving mode in the first area 310. In the second area 320, the handheld power tool 100 is operated in rotary impact mode.
• FIG. 5b shows the output signal after the bandpass filter has filtered the input signal.
• FIG. 6 shows the measured signal of the operating variable 200 for the case that the frequency analysis is used as the frequency-based comparison method.
• the first area 310 is shown in which the hand-held power tool 100 is in the screwing mode.
• Time t or a quantity correlated with time is plotted on the abscissa x in FIG. 6a.
• the signal of the operating variable 200 is shown transformed, it being possible, for example, to transform time into a frequency by means of a Fast Fourier Transformation.
• the frequency f is plotted on the abscissa x 'of FIG. 6b, so that the amplitudes of the signal of the operating variable 200 are shown.
• FIG. 6c and d the second region 320 is shown, in which the handheld power tool 100 is in rotary impact mode.
• FIG. 6c shows the measured signal of the operational variable 200 plotted over time in rotary impact operation.
• FIG. 6d shows the transformed signal of the operational variable 200, where the signal of the operational variable 200 is plotted against the frequency f as the abscissa x '.
• FIG. 6d shows characteristic amplitudes for rotary impact operation.
• FIG. 7a shows a typical case of a comparison using the comparative comparison method of parameter estimation between the signal of an operating variable 200 and a state-typical model signal shape 240 in the first area 310 described in FIG. 2. the signal of farm size 200 has a course that deviates significantly from this.
• the result of the comparison carried out in method step S2 between the model signal form 240 typical for the state and the signal of the operating variable 200 is that the degree of correspondence between the two signals is so low that in method step S3 the first operating state is not established.
• FIG. 7b shows the case in which the first operating state is present and therefore the state-typical model signal shape 240 and the signal of the operating variable 200 show a high degree of correspondence overall, even if deviations can be determined at individual measurement points.
• the decision as to whether the first operating state is present can be made.
• FIG. 8 shows the comparison of the state-typical model signal shape 240, see FIGS. 8b and e, with the measured signal of the operating variable 200, see FIGS. 8a and 8d, for the case that the cross-correlation is used as the comparative comparison method.
• FIGS. 8a-f the time or a quantity correlating with time is plotted on the abscissa x.
• the first area 310, the screwdriving operation, is shown in FIGS. 8 a - c.
• the second region 320, the first operating state, is shown in FIGS. 8 d-f.
• the measured signal of the operating variable, FIGS. 8a and 8d is correlated with the state-typical model signal form, FIGS. 8b and 8e.
• FIGS. 8c and 8f Respective results of the correlations are shown in FIGS. 8c and 8f.
• FIG. 8c the result of the correlation is shown during the first area 310, it being evident that there is little agreement between the two signals.
• the screwdriving operation is therefore present in FIG. 8c.
• the result of the correlation during the second region 320 is shown in FIG. 8f. It's in figure 8f it can be seen that there is a high degree of correspondence, so that the handheld power tool 100 is operated in the first operating state.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Portable Power Tools In General (AREA)
• Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

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• 2019
  • 2019-03-25 DE DE102019204071.3A patent/DE102019204071A1/de active Pending
• 2020
  • 2020-03-02 CN CN202080038832.6A patent/CN113874172A/zh active Pending
  • 2020-03-02 EP EP20710078.5A patent/EP3946818A1/de active Pending
  • 2020-03-02 WO PCT/EP2020/055397 patent/WO2020193083A1/de unknown
  • 2020-03-02 JP JP2021555261A patent/JP7488830B2/ja active Active
  • 2020-03-02 US US17/441,818 patent/US20220176527A1/en active Pending

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