Handheld machine tool with electronically commutated motor

Abstract

In a handheld machine tool (100), there is an electronically commutated motor (120) and a motor electronics component (200). The electronically commutated motor has a motor winding (172). The motor electronics component is used to electronically commutate the motor winding (172) and is adjustable to an electrically pre-adjusted angle (α) that can be pre-given by the motor electronics component (200) for electronically commutating the motor winding (172) in order to match different mechanical load conditions of the electronically commutated motor (120).

Description

Technical Field

[0001] The invention relates to a handheld power tool having an electronically commutated motor with a motor winding and a motor electronics component for electronic commutation of the motor winding. Background Art

[0002] Electronically commutated motors are widely used in mains-operated or mains-independent handheld power tools, in particular, due to their low maintenance costs and relatively good adjustability. Such electric motors usually require complex power electronics for regulation. In the power electronics, a preset angle of commutation is usually stored for at least each operating point of the motor that is relevant for operation, or the preset angle can be adaptively changed by means of intelligent software without the user being able to intervene. The user cannot influence the preset angle and therefore cannot adapt it to a suitable operating point of the motor.

[0003] In many applications, the maximum possible mechanical power of the motor cannot be used. Even with adaptive pre-angle adjustment, it is not possible to detect controlled operation in the area of ​​the motor's natural characteristic curve. As the mechanical load on the motor increases, the current I rms The true effective value (= root mean square) of increases proportionally, so that when the load increases further, the motor cannot be operated optimally until the speed drops for the first time. The consequence is unfavorable heating or high current peaks in the motor windings in the adjusted speed range. As a result, the temperature change load of the motor increases, so that the insulation system of the motor winding ages faster, which can lead to failure of the entire motor. In addition, due to the current I in the motor winding in the case of a non-optimal presetting angle, rms As the effective value of increases, the efficiency of the electronically commutated motor decreases.

[0004] DE 103 46 711 A1 relates to a method for commutating a brushless DC motor having at least one motor winding. In a DC motor, the position of the rotor relative to the stator is determined and a commutation signal is generated therefrom, wherein the motor winding is simultaneously energized at a preset commutation angle in accordance with the commutation signal. Depending on the design and the current supply method of the motor, it is particularly proposed that when a commutation signal occurs, the polarity of the winding current is detected and the commutation angle is changed in accordance with the detected polarity of the winding current in such a way that when the commutation signal occurs, the winding current is essentially zero or passes through a zero point. The known method for commutating a brushless DC motor enables the commutation angle or the so-called preset angle to be automatically improved by an electronic motor control device with little additional technical effort and minimal additional costs. Summary of the invention

[0005] The invention relates to a handheld power tool having an electronically commutated motor with a motor winding and a motor electronics component, the electronically commutated motor having a motor winding, the motor electronics component being used for electronic commutation of the motor winding. An electrical presetting angle for electronic commutation of the motor winding that can be predefined by the motor electronics component can be set in order to adapt to different mechanical load conditions of the electronically commutated motor. Preferably, the predefinable electrical presetting angle can be set by a user of the handheld power tool.

[0006] In particular, the efficiency of the electronically commutated motor can thus be improved. The temperature change load of the motor winding under high mechanical loads is reduced, so that the service life of the motor is increased and, when the handheld power tool is battery-operated, the service life of the battery is extended. The invention is provided in particular for handheld power tools, such as hammer drills, angle grinders, eccentric grinders and circular saws, which can experience extreme overload situations during operation.

[0007] According to an advantageous extension, in manual mode, the user can adjust the preset angle in at least two levels by means of at least one operating element, the at least two levels being respectively provided with markings which together with the operating element form an operating zone. Preferably, in manual mode, the user can adjust the preset angle in three levels by means of at least one operating element. Thus, the user can fully and intuitively control the power of the handheld power tool. At least two, preferably three markings can be respectively marked with Arabic numerals "1", "2" and "3" for load conditions that usually occur during the operation of the handheld power tool. The mechanical torque that can be called up by the electronically commutated motor increases with each level.

[0008] Preferably, the first level is assigned to a light load case of the electronically commutated motor, the second level is assigned to a medium load case of the electronically commutated motor, and the third level is assigned to a heavy load case of the electronically commutated motor. This results in a sufficiently fine adaptability of the presetting angle even in actual use of the handheld power tool. In the case of a handheld power tool designed as an eccentric grinder, for example, a light load case occurs during light wood processing in the form of fine grinding, a medium load case occurs during rough wood processing, and a heavy load case occurs during polishing work with high pressure.

[0009] Preferably, the first level is assigned a preset angle of -30°, the second level is assigned a preset angle of -60°, and the third level is assigned a preset angle of -90°. The handheld power tool can thus be operated in a suitable manner depending on the respective current load conditions.

[0010] In a technically advantageous embodiment, a preset angle control unit is provided, which is designed to determine the preset angle in a semi-automatic mode or a fully automatic mode as a function of at least two load situations of the electronically commutated motor, in particular load situations in the form of a light load situation, a medium load situation and / or a heavy load situation. The setting of the preset angle can thus be simplified. In the semi-automatic mode, the user only needs to set the preset angle predetermined by the preset angle control unit by means of an operating element, whereas in the fully automatic mode no user work is required at all.

[0011] According to another advantageous embodiment, an indicator unit is provided as part of the operating panel, which is designed to display the preset angle determined by the preset angle control unit according to the current load situation and to be manually set by the user using the operating element in the semi-automatic mode, thereby providing assistance to the user in correctly setting the preset angle.

[0012] Preferably, for each of the at least two load situations, the display unit has at least one display element that can be visually perceived by the user, in particular the display unit has at least two LEDs of different colors. As a result, for the respective load situation, a signal that is clearly perceptible to the user is given of the presetting angle to be selected. For example, in the case of a handheld power tool with a multi-stage mechanical shift transmission, such as an electric drill, an indicator for the current load state or the torque to be applied by the electronically commutated motor can be provided, which indicator can be associated with a shifting recommendation for the mechanical shift transmission if necessary.

[0013] According to a technically advantageous embodiment, the presetting angle control unit is designed to detect at least one rotational speed and / or torque of the electronically commutated motor and / or current of a motor winding of the electronically commutated motor. Based on these measured values, a presetting angle suitable for the respective current load situation of the electronically commutated motor can be determined.

[0014] Preferably, a parameter table for determining the preset angle is stored in the preset angle control unit, wherein the respectively used preset angle can be determined with the aid of the parameter table and at least with the aid of the measured current rotational speed of the electronically commutated motor and / or the current torque and / or the current current of the motor winding of the electronically commutated motor. For this purpose, the empirical data required for selecting a suitable preset angle or the characteristic curve of all operation-related load conditions of a specific electronically commutated motor installed in the hand-held power tool are stored in the parameter table.

[0015] Preferably, in fully automatic mode, the preset angle is set by means of motor electronics which are correspondingly controlled by the preset angle control unit. The portable power tool is thus easier to operate and operating errors by the user or the user can be largely excluded.

[0016] According to a technically advantageous expansion scheme, the fully automatic mode can be switched to a semi-automatic mode or a manual mode by the user by means of at least one other operating element. Thus, at least one change can be made between the semi-automatic mode and the fully automatic mode of the handheld power tool if necessary.

[0017] In an advantageous development, the operation-related data of all load conditions occurring during the actual operation of the electronically commutated motor, in particular the rotational speed, torque and at least the current of the motor windings and the temperature of the motor windings, can be transmitted to an external server for evaluation by means of the motor electronics and / or the presetting angle control unit. In this way, user errors can be detected and the development of subsequent electronically commutated motors can also be further improved or promoted. For this purpose, the handheld power tool can be equipped with any desired wireless and / or wired interfaces, such as WLAN, LAN, etc. In the context of this specification, the term "external server" is used synonymously with the term "Cloud" which is particularly popular in the English language environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the following description, the invention is explained in more detail based on the exemplary embodiments shown in the drawings. The drawings show:

[0019] Figure 1 A perspective view of a handheld power tool having an electronically commutated motor, motor electronics and operating elements of an operating panel for setting a preset angle,

[0020] Figure 2 Schematic diagram of an EC motor having Figure 1 Motor electronics and pre-angle control unit,

[0021] Figure 3 Figure 2 The speed-torque characteristic curve of the EC motor,

[0022] Figure 4 The electric pre-adjustment angle is shown at 9000 rpm and 10000 rpm. Figure 2 The torque-current characteristic curve of the EC motor,

[0023] Figure 5 Figure 2The torque-current characteristic curve of the EC motor at 7000 rpm and 8000 rpm according to the electrical pre-adjustment angle,

[0024] Figure 6 Figure 2 The torque-current characteristic curve of the EC motor at 5000 rpm and 6000 rpm according to the electrical pre-adjustment angle,

[0025] Figure 7 Belong to Figure 2 Parameter table of EC motors. DETAILED DESCRIPTION

[0026] Figure 1 An exemplary mains-operated handheld power tool 100 is shown, which is here only exemplarily implemented as an eccentric grinder 102. The handheld power tool 100 has a machine housing 104, in which an electric drive motor 118 is arranged, wherein the drive motor 118 is configured as an electronically commutated motor 120. Unlike the handheld power tool 100, which is here only exemplarily implemented as an eccentric grinder 102, the handheld power tool can also be configured as a hammer drill, an angle grinder or a circular saw. The machine housing 104 has a handle 106 and a mains feeder 110 for connecting to a local AC power grid, the handle having a mains switch 108. It should be noted here that the present invention is not limited to mains-operated handheld power tools, but can also be applied to cordless, battery-operated handheld power tools. In the further description, the term “EC motor 120” is used to refer to an electronically commutated motor 120 which eccentrically drives a grinding disc 140 by means of an output shaft 130 accommodated in a base section 138 of the machine housing 104. Grinding means, such as a grinding disc 144 made of fiber-reinforced paper or the like, can be fastened to an underside 142 of the grinding disc 140 that faces a workpiece (not shown).

[0027] EC motor 120 has a motor winding (not shown here) which preferably has three phase windings (see Figure 2 , reference numerals 172, 174, 176, 178). The electrical presetting angle α assigned to the handheld power tool 100 is also referred to as the “advance angle” in the literature. The electrical presetting angle α specifies when the assigned motor electronics 200 applies voltage to a specific phase winding of the EC motor 120. For example, the EMK curve (electromotive force curve) of two successive motor phases E lektro m Otorish K raft- KThe intersection of the EMK curves of the two phases of the EC motor 120 can be regarded as a reference point. When the precontrol angle α is less than 0°, the voltage is applied earlier in time. Thus, a precontrol angle α of -30° means that the motor electronics 200 applies the voltage 30° before the intersection of the EMK curves of the two phases of the EC motor 120. In the case of a positive precontrol angle greater than 0°, the voltage is applied correspondingly with a time delay or later.

[0028] In addition, a suction device 150 for dust released during machining of workpieces with the eccentric grinder 102 is integrated into the base section 138 of the machine housing 104. For example, a commercial household vacuum cleaner can be attached to the suction device 150. By means of a locking element, preferably a push-button locking element 112 in the handle 106, the mains switch 108 can be permanently held in the switched-on position if necessary. By pressing the locking element 112 down again, the mains switch 108 can be unlocked again so that the mains switch 108 is released again to quickly switch off the eccentric grinder 102. As indicated by the dotted double arrow 202, the EC motor 102 is regulated and / or controlled by a high-performance digital motor electronics 200.

[0029] Preferably, an operating panel with an operating element 222 is integrated into the handle 106 of the machine housing 104, wherein the operating element 220 is designed here merely as an example as a rotary switch 224 with three levels. The rotary switch 224 is used to select a preset angle α of the EC motor 120 stored in the motor electronics 200, so that the user of the handheld power tool 100 can adapt to different load situations of the handheld power tool 100 or of the EC motor 120 in the so-called manual mode. In the manual mode of the handheld power tool 100, for example, there are at least two, preferably three, user-adjustable levels: light work, medium work, and work with heavy load of the handheld power tool 100. The user can select each level manually, and each individual setting is assigned precisely a pre-determined or calculated preset angle α, which ensures a maximum power output of the EC motor 120 under the corresponding load situation, and thus ensures that the work with the handheld power tool is improved without the risk of thermal overload or the like. At the same time, the battery life is preferably extended when the handheld power tool is battery operated. In the context of the present invention, the user of the handheld power tool 100 can set the preset angle α to match different load conditions of the handheld power tool 100 or of the EC motor 120 .

[0030] Alternatively or optionally, the operating panel 220 has at least two markings, as shown in the figure and preferably has first, second and third markings 230, 232, 234 that can be easily perceived by the user visually, each of which corresponds to one of the at least two, preferably three levels of the rotary switch 224. As shown here, the first marking 230, the second marking 232 and the third marking 234 can be provided with three Arabic numerals "1", "2" and "3", for example. In addition, for better differentiation, the three markings 230, 232, 234 can be configured in different colors. For example, the first marking 230 can be colored green, the second marking 232 can be stored in yellow and the third marking 234 can be colored red. The first marking 230 represents a light mechanical load condition of the handheld power tool 100 or the EC motor 120, the second marking 232 represents a medium mechanical load condition of the handheld power tool 100 or the EC motor 120, and the third marking 234 represents a heavy mechanical load condition of the handheld power tool 100 or the EC motor 120. For example, if the handheld power tool 100 is an angle grinder (not shown), light load situations occur during roughing operations, medium load situations occur during separation operations, and heavy load situations occur during intensive material removal operations on large areas of the workpiece to be machined.

[0031] exist Figure 1 In the exemplary embodiment shown, the linear marking 226 of the rotary switch 224 points to the second marking 232, so that the presetting angle α for the medium load situation of the EC motor 120 is activated by the motor electronics 200. Correspondingly, by turning the rotary switch 224 by the user, the presetting angle α for the light load situation and the heavy load situation can be set by turning the rotary switch 224 counterclockwise or clockwise respectively until the marking 226 points to the first and third markings 230, 234 respectively. The first level with the first marking 230 is preferably assigned a presetting angle α of up to -30° by the motor electronics 200. The second level activated when the marking 226 of the rotary switch 224 points to the second marking 232 as shown in the figure is assigned a presetting angle α preferably between -15° and -60°, and, correspondingly, the third level with the third marking 234 is assigned a presetting angle α preferably between -30° and -90°. Preferably, a presetting angle α of -30° is assigned to the first level, a presetting angle α of -60° is assigned to the second level, and a presetting angle α of -90° is assigned to the third level. Alternatively, a continuous, i.e. stepless, adjustability of the presetting angle α can also be provided, wherein, instead of the three-level rotary switch 224, for example, an analog potentiometer or a digital potentiometer (not shown) can be used as the operating element 222.

[0032] Alternatively, the rotary switch 224 of the operating panel 220 can also have only two or more than three levels with corresponding markings, each of which in turn is assigned a preset angle α that is individualized within the motor electronics 200 and is suitable for the respective application of the handheld power tool 100. As a result, the handheld power tool 100 can be operated at maximum power in any application by simple and intuitive user intervention without the risk of thermal overloading of the EC motor 120.

[0033] Figure 2 The diagram shows an EC motor 120 and associated motor electronics 200. Figure 1 The EC motor 120 has here, merely as an example, a permanently excited inner rotor 160 which is connected to the output shaft 130 in a rotationally fixed manner. The inner rotor 160 is coaxially surrounded by the outer stator 170, so that the EC motor 120 is configured here only as an inner rotating part. Alternatively, the EC motor 120 can also be designed as an outer rotor. The outer stator 170 has a motor winding 172 which is preferably designed with three individual windings 174 , 176 , 178 or phase windings which are each arranged offset by 120° on the circumferential side.

[0034] The motor electronics 200 supplies the motor winding 172 having three individual windings 174 , 176 , 178 in the outer stator 170 with a three-phase current I rms In other words, alternating current is supplied to generate a rotating magnetic field, so that as shown by the rotation direction arrow 199, the inner rotor 160 rotates with the output shaft 130 either clockwise or counterclockwise at a variable speed n. Here, the EC motor 120 outputs a mechanical torque M through the output shaft 130, and thus according to the equation P mech =n*M output mechanical power P mech For controlling and / or regulating the EC motor 120 , the motor electronics 200 are preferably designed to continuously detect in real time a rotor angle indicating the respective rotational angle position of the inner rotor 160 relative to the outer stator 170 . The current rotational speed n of the inner rotor 160 , the corresponding current I in the motor winding 172 rms , the torque M on the output shaft 130 and the temperature θ of the motor winding 172. The ohmic resistance R of the motor winding 172 is, for example, constant at 4.7Ω. In addition, the structure and function of an electronically commutated motor such as the EC motor 120 are sufficiently familiar to those skilled in the art of electric drive technology, and therefore, will not be described in more detail here.

[0035] In addition, a pre-setting angle control unit 300 is provided, which is designed to adjust the angle in a semi-automatic mode or a fully automatic mode according to the EC motor 120 that has already been adjusted. Figure 1 The invention relates to determining a suitable presetting angle α for at least two, preferably three mechanical load conditions explained in the context of the description of the invention. For this purpose, the operating panel 220 of the handheld power tool 100 has, in addition to a three-stage rotary switch 224 with a linear marking 226 as an operating element, an indicator unit 250, which is formed here as an example with three discrete indicator elements 252, 254, 256, such as light-emitting diodes (LEDs) not shown and of different colors as required. Here, the first indicator element 252 is assigned to the first marking 230 of the operating panel 220, the second indicator element 254 is assigned to the second marking 232 of the operating panel 220, and the third indicator element 256 is assigned to the third marking 234 of the operating panel 220. The indicator elements 252, 254, 256 can be positioned below the markings 230, 232, 234 of the operating panel 220, wherein the markings 230, 232, 234 are designed to be light-transmissive in this case. For example, the first indicator element 252 can be implemented with a green LED, the second indicator element 254 can be implemented with a yellow LED, and the third indicator element 256 can be implemented with a red LED. The indicator unit 250 is designed as part of the operating area 220 to display in the semi-automatic mode a suitable presetting angle α which is determined by the presetting angle control unit 300 according to the current mechanical load situation of the EC motor 120 and is to be manually set by the user using the operating element 222. For this purpose, the presetting angle control unit 300 is designed to at least detect the rotational speed n of the EC motor 120 and / or the mechanical torque M and / or the current I of the motor winding 172 of the EC motor 120. rms An evaluation or test is performed if motor electronics 200 has not yet determined and provided these parameters.

[0036] In fully automatic mode, the preset angle α is set autonomously, i.e. without user involvement, by means of the motor electronics 200 which are correspondingly controlled by the preset angle control unit 300. In this case, the current mechanical load of the EC motor 120 (light, medium, heavy) is displayed to the user in a visually perceptible manner, if necessary, by means of the display unit 250, so that the user is always aware of the respectively activated preset angle α.

[0037] The operating panel 220 is preferably equipped with a further operating element 240 for switching between the semi-automatic mode and the fully automatic mode. The operating element 240 can be implemented, for example, as a snap-in button 242, which can be activated, for example, by pressing down and deactivated by pressing down again, wherein the corresponding switching state of the button 242 and thus whether the semi-automatic mode or the fully automatic mode is activated can be displayed to the user by means of further indicator elements (not shown), such as LEDs or the like.

[0038] A parameter table 400 for determining a correspondingly suitable presetting angle α is stored in the presetting angle control unit 300 or the motor electronics 200 (see in particular Figure 7 ). With the aid of table 400 and at least with the aid of the measured current rotational speed and / or current mechanical torque of EC motor 120 and / or current current I in motor winding 172 of EC motor 120 rms As indicated by the double-headed arrow 204, preferably in fully automatic mode, the presetting angle α suitable for the specific mechanical load conditions of the EC motor 120 is set by means of the motor electronics 200 correspondingly controlled by the presetting angle control unit 300. Alternatively, the presetting angle α can also be set directly by the presetting angle control unit 300.

[0039] In fully automatic mode, the motor electronics 200 detects how high the current torque of the EC motor 120 is and sets the preset angle α to a predetermined discrete value based on the discrete values ​​in the parameter table, just as in purely manual operation. Alternatively, the preset angle α can also be set continuously or steplessly based on the current light, medium or heavy load situation. With the help of the motor electronics 200 and / or the preset angle control unit 300, all operation-related data 312 or measured values ​​of all mechanical load situations occurring during actual industrial use of the EC motor 120, in particular in terms of rotational speed n, mechanical torque M, at least the current I in the motor winding 172, can be transmitted to an external server 310 or the so-called “cloud”. rms , and the temperature θ in the region of the motor winding 172 for more detailed evaluation and improvement. Thus, a large number of handheld power tools 100 in actual use respectively send corresponding operation-related data or measured values ​​to the external server 310, which can be particularly helpful for continuous improvement of the data or parameters for setting a suitable presetting angle α stored in the parameter table 400 of the presetting angle control unit 300 for subsequent handheld power tools. If necessary, the data or measured values ​​improved in this way can also be downloaded to the already delivered handheld power tools in the process of digital updating and respectively stored in their motor electronics and / or presetting angle control unit.

[0040] Figure 3 Show Figure 2 An exemplary speed-torque characteristic curve of an EC motor. The graph 450 comprises an ordinate and an abscissa. The mechanical torque M that can be output by the EC motor 120 is plotted on the abscissa in steps of 0.05 Nm each, and the speed n of the EC motor is plotted on the ordinate in steps of 1000 rpm or U / min (revolutions per minute). The unregulated speed-torque characteristic curve 452 extends slightly downward from a torque of 0.1 Nm at 10,000 U / min to a point of maximum torque of 0.45 Nm at a speed of approximately 5000 U / min. The first, second and third straight lines 454, 456, 458 correspond to pre-settable characteristic curves, which can be achieved by adjusting the EC motor 120 with the aid of the motor electronics 200 (see in particular Figure 2 , reference numerals 100, 200). This means that, before the respective turning points 460, 462, 464, the speed n of the EC motor 120 remains essentially constant despite the increase in torque M and only decreases after reaching the respective turning points 460, 462, 464, coinciding with the slightly concavely curved speed-torque characteristic curve 452. Before the respective turning points, the EC motor 120 operates at an unsuitable presetting angle α, whereby the copper heat loss in the motor winding increases significantly.

[0041] In the following, this process is briefly explained assuming that the operating point of the EC motor 120 is constant and the presetting angle α is different. The speed n of the EC motor 120 is, for example, 10000 rpm and the ohmic resistance R of the motor winding is constant at 4.7Ω. The heat loss power of the EC motor 120 with three single windings is calculated using the following equation:

[0042] (1)

[0043] Based on equation (1), in the first case where the preset angle α is -30°, the current I rms The current I is 3.99A, while for the second case where the preset angle α is -45°, a current I of 16.4A appears. rms .

[0044] Then, for the first case, using equation (1) we get

[0045] P v,Cu =3·(3.99A) 2 4.7Ω=224.47W

[0046] If we change the I rms Putting the current of 16.4A into equation (1), we get:

[0047] (2)P v,Cu =3·(16.4A) 2 4.7Ω=3792.3W

[0048] This simple calculation example impressively shows that if the presetting angle α is incorrect, extremely high heat losses P can occur in the motor windings of the EC motor 120 . v,cu , because the heat loss power in the second case is much higher than in the first case. However, such a high heat loss cannot be achieved in practice, because the EC motor 120 burns out before this.

[0049] Figures 4 to 6 - These figures are referred to simultaneously in the further description - respectively show the electrical presetting angle α at different speeds n. Figure 2 Two torque-current characteristic curves of the EC motor 120.

[0050] Figures 4 to 6 Six graphs 500, 502, 504, 506, 508, 510 are shown, wherein the graphs 500 to 510 reflect the electromechanical relationships for speeds n=10000 U / min, n=9000 U / min, n=8000 U / min, n=7000 U / min, n=6000 U / min and n=5000 U / min as operating points of the EC motor 120. For this purpose, the mechanical torque M of the EC motor 120 is plotted on a first ordinate in each of the six graphs 500, 502, 504, 506, 508, 510, and the current I is plotted on a second ordinate as a function of the preset angle α increasing along the abscissa. rms , whereby a current-α characteristic curve 520 , 524 , 528 , 532 , 536 , 540 and a correspondingly assigned torque-α characteristic curve 522 , 526 , 530 , 534 , 538 , 542 are obtained in each of the six graphs 500 to 510 . Figure 4 The characteristic curves 520, 522 and the characteristic curves 524, 526 are shown here. Figure 7 The row Z of the table 1 and Z 2 A graphical representation of the values ​​in . Figure 5 The characteristic curves 528, 530 and the characteristic curves 532, 534 are formed in Figure 7 The row Z of the table 3 , Z 4 Graphical transformation of the values ​​in . Figure 6 The same is true for characteristic curves 536, 538 and characteristic curves 540, 542, which represent Figure 7The row Z of the table 5 , Z 6 Graphical transformation of the values ​​in .

[0051] Figure 7 Show Figure 2 An exemplary parameter table 400 of an EC motor 120 with operation-related, empirically determined measured values ​​for setting the preset angle α is shown in column S of parameter table 400. 1 The speed n of the EC motor 120 is listed in rpm, column S 2 Contains the mechanical pre-adjustment angle αmech of the EC motor 120 in degrees, column S 3 Column S contains the electrical pre-adjustment angle αel of the EC motor 120 in degrees. 4 Contains the current I in A (ampere) rms , column S 5 The corresponding mechanical (output) torque M of the EC motor 120 in Nm is included. For example, from the parameter table 400 by row Z 1 At a speed n of 10000 U / min, the following is obtained: 3 The suitable electrical pre-adjustment angle α is -30°, because in this case the current I rms In line Z 1 With column S 4 In the intersection area, I rms =3.99533A minimum. Similarly, when the speed n is 9000U / min, row Z 2 The suitable pre-adjustment angle α is column S 3 -60° in the middle, when the speed n is 8000U / min, the Z 3 The suitable pre-adjustment angle α is column S 3 -45°, when the speed n is 7000U / min, the Z 4 The suitable pre-adjustment angle α is column S 3 -45° in the middle, when the speed n is 6000U / min, the Z 5 The suitable pre-adjustment angle α is column S 3 -90° in the middle, when the speed n is 5000U / min, the Z 6 The suitable pre-adjustment angle α is column S 3 -60° in the middle.

[0052] It should be noted that the values ​​of parameter table 400 are merely exemplary and cannot be regarded as limiting the present invention. Other selection criteria for determining a suitable presetting angle α are also possible, wherein all measured values ​​or data contained in the table can be considered within the framework of the selection criteria.

[0053] Correspondingly, in fully automatic mode, for each load situation (light, medium, heavy) of the EC motor 120 of the handheld power tool 100 and depending on the type and properties of the respective handheld power tool 100, a suitable presetting angle α for the EC motor 120 can be predetermined independently and autonomously by means of the presetting angle control unit 300 and in this case controlled by the motor electronics 200, without requiring any assistance from the user (see Figure 2 , reference numerals 100, 102, 120, 200, 300). In the semi-automatic mode, the motor electronics 200 and / or the preset angle control unit 300 indicate to the user by means of the optical display element 250 a suitable preset angle α, which should however be manually set by the user by means of the operating element 222. Alternatively or additionally, an acoustic and / or tactile notification of the suitable preset angle α to be manually set can also be provided. Only in the fully manual mode does the user manually set a suitable preset angle α by means of the operating element 222 according to his personal perception of the specific working situation performed with the handheld power tool 100, in particular according to a light, medium or heavy load situation, without activating the preset angle control unit 300. In every load situation, the EC motor 120 according to the invention of the handheld power tool 100 can be operated at a suitable power with high energy efficiency without the risk of overheating. Since overheating is avoided, the thermal insulation system of EC motor 120 ages less and the service life of handheld power tool 100 is increased. In addition, current peaks of EC motor 120 of handheld power tool 100 and overloading of the local power grid are avoided.

Claims

1. A handheld power tool (100) comprising an electronically commutated motor (120) having a motor winding (172) and a motor electronics component (200), wherein the electronically commutated motor has a motor winding (172), the motor electronics component being used for electronic commutation of the motor winding (172), characterized in that: An electrical pre-adjustment angle for electronic commutation of the motor winding (172) which can be pre-set by the motor electronics (200) can be adjusted to match different mechanical load conditions of the electronically commutated motor (120), wherein in manual mode the pre-adjustment angle can be adjusted by a user in at least two levels by means of at least one operating element (222), and the at least two levels are respectively provided with markings (230, 232, 234), which together with the operating element (222) form an operating area (220).

2. The handheld power tool (100) according to claim 1, characterized in that The at least two levels include a first level, a second level and a third level, the first level being assigned to a light load condition of the electronically commutated motor (120), the second level being assigned to a medium load condition of the electronically commutated motor (120), and the third level being assigned to a heavy load condition of the electronically commutated motor (120).

3. The handheld power tool (100) according to claim 2, characterized in that The first level is assigned a preset angle of -30°, the second level is assigned a preset angle of -60°, and the third level is assigned a preset angle of -90°.

4. The handheld power tool (100) according to claim 1, characterized in that A presetting angle control unit (300) is provided, which is designed to determine the presetting angle in a semi-automatic mode or a fully automatic mode according to at least two load conditions of the electronically commutated motor (120).

5. The handheld power tool (100) according to claim 4, characterized in that The at least two load conditions include a light load condition, a medium load condition and / or a heavy load condition.

6. The handheld power tool (100) according to claim 4 or 5, characterized in that: An indication unit (250) is provided as part of the operating area (220), which is designed to display in the semi-automatic mode a preset angle which is determined by the preset angle control unit (300) according to the current load situation and is to be manually set by a user using an operating element.

7. The handheld power tool (100) according to claim 6, characterized in that For each of the at least two load conditions, the indication unit (250) has at least one indication element (252, 254, 256) that can be visually perceived by a user; the indication unit has at least two LEDs of different colors.

8. The handheld power tool (100) according to claim 4 or 5, characterized in that: The presetting angle control unit (300) is designed to detect at least one rotational speed and / or torque of the electronically commutated motor (120) and / or a current of a motor winding (172) of the electronically commutated motor (120).

9. The handheld power tool (100) according to claim 4 or 5, characterized in that: A parameter table (400) for determining the presetting angle is stored in the presetting angle control unit (300), wherein the corresponding presetting angle to be used can be determined with the aid of the parameter table (400) and at least with the aid of the measured current rotational speed and / or current torque of the electronically commutated motor (120) and / or the current current of the motor winding (172) of the electronically commutated motor (120).

10. The handheld power tool (100) according to claim 4 or 5, characterized in that: In the fully automatic mode, the preset angle is set by means of the motor electronics (200) which are correspondingly controlled by the preset angle control unit (300).

11. The handheld power tool (100) according to claim 10, characterized in that The fully automatic mode can be switched by the user into a semi-automatic mode or into a manual mode by means of at least one further operating element (240).

12. The handheld power tool (100) according to claim 1, characterized in that Operation-related data (312) of all load situations occurring during actual operation of the electronically commutated motor can be transmitted by means of the motor electronics (200) to an external server (310) for evaluation.

13. The handheld power tool (100) according to claim 4, characterized in that Operation-related data (312) of all load situations occurring during actual operation of the electronically commutated motor can be transmitted by means of the presetting angle control unit (300) to an external server (310) for evaluation.

14. The handheld power tool (100) according to claim 12 or 13, characterized in that The operation-related data (312) relates to rotational speed, torque, current of the motor windings (172), and temperature of the motor windings (172).

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