DRIVE MOTOR FOR A VACUUM CLEANER OR MACHINE TOOL

Description

[0001] The invention relates to a drive motor for a suction device or a machine tool in the form of a hand-held machine tool or a semi-stationary machine tool, wherein the drive motor has a stator with a stator coil arrangement and a rotor with a motor shaft which is rotatably mounted on the stator or relative to the stator by means of a bearing arrangement about an axis of rotation, wherein the rotor has a magnet arrangement with permanent magnets arranged in a ring around the axis of rotation, wherein a sensor arrangement is fixedly arranged relative to the stator to detect a respective angular position of the rotor relative to the stator, which has at least two sensors which are designed to generate, in particular, digital switching signals for a current-sensing device for energizing the stator coil arrangement, so that the rotor can be driven to rotate about the axis of rotation by energizing the stator coil arrangement.

[0002] Such a drive motor is explained, for example, in WO 2011 / 159674 A1.

[0003] One such drive motor is, for example, an electronically commutated motor, or EC motor. A current supply unit is provided to energize the motor's stator coil assembly. To ensure correct energization of the stator coil assembly, and in particular to energize the stator coils at appropriate switching times, the current supply unit requires information about the respective angular position of the rotor, for which the sensor assembly is provided. However, during the operation of such a drive motor, interference effects occur, such as the superposition of the magnetic fields of the permanent magnets and the magnetic fields generated by the stator coil assembly, resulting in suboptimal switching signals from the sensor assembly.

[0004] It is therefore the object of the present invention to provide an improved drive motor, in particular an improved electronically commutated drive motor.

[0005] To solve the problem, a drive motor of the type mentioned above is provided with at least two sensors designed to detect two waves of a rotating magnetic field of the rotor that are phase-shifted by an angle of rotation. The sensors generate the switching signals depending on whether a magnetic wave of the rotating field passing through the sensor exceeds or falls below a switching threshold of the sensor. The permanent magnets of the magnet arrangement have angular distances to each other with respect to the axis of rotation, such that the magnetic waves of the rotating field at the location of the respective sensor have continuous, in particular approximately sinusoidal, half-waves with peak regions between continuously rising and falling edges. The waves have transition sections between successive half-waves of different polarity.wherein the waves in the transition sections have at least one step or jump or discontinuity, and that the switching thresholds of the sensors are arranged in the region of the continuously rising or falling edges of the half-waves.

[0006] The invention further provides for a machine tool, in particular a hand-held machine tool or a semi-stationary machine tool, with a drive motor according to the invention. The machine tool is, for example, a saw, drill, screwdriver, or the like. A semi-stationary machine is understood to be, for example, a mobile machine that can be transported to a place of use, such as a construction site, in particular a table saw or the like.

[0007] The basic idea is that the sensor arrangement should not be located in the area of ​​the transition sections, where steps, jumps or other discontinuities can be observed, but rather that the switching thresholds should lie outside the transition sections.

[0008] The drive motor according to the invention is, for example, a brushless DC motor (also abbreviated as BLDC or BL motor) (BL = Brushless, DC = Direct Current). The drive motor can also be a BLAC motor (BL = Brushless, AC = Alternating Current). The drive motor can also be an electronically commutated motor (EC motor), a permanent magnet synchronous motor (PMSM), or the like.

[0009] The hysteresis of a sensor is preferably set according to the invention such that the switching thresholds of the sensors lie in the range of the continuously rising or falling edges of the half-waves.

[0010] The sensor arrangement advantageously includes magnetic sensors or magnetic field sensors designed for outputting digital switching signals, for example Hall sensors, magneto-resistive sensors (MR sensors), in particular anisotropic MR sensors or AMR sensors, GMR sensors, magneto-optic sensors or the like.

[0011] It is possible, for example, for an evaluation unit of the sensor arrangement to generate a digital switching signal from an analog measurement signal of a sensor by comparing the analog measurement signal with the respective switching threshold. Preferably, however, the sensors already output digital switching signals. Accordingly, it is advantageous if the switching thresholds are provided and / or set at or on the sensors. The switching thresholds at or on the sensors can also be preset and / or determined by production accuracies or production conditions.

[0012] While it would be possible in principle for the rotor to have a magnet designed as a switching or sensor magnet, which is not intended to interact with the stator coil assembly to drive the rotor, it is preferred that the rotor only has magnets intended for driving or actuating its rotation. The permanent magnets of the magnet assembly thus preferably serve to drive the rotor in conjunction with the stator coil assembly, or are designed and intended for this purpose. The permanent magnets already necessary for driving the rotor and thus the drive motor are therefore used for an additional purpose: actuating the sensors of the sensor assembly.

[0013] However, it should be mentioned at this point that at least one additional magnet or magnetic encoder or magnetic switching encoder can be provided in addition to the permanent magnet intended for rotating the rotor, the magnetic field of which is scanned by at least one sensor of the sensor arrangement.

[0014] However, it is preferred that no magnetic encoder or magnet intended solely for actuating the sensor arrangement and not for rotating the rotor is arranged on the rotor. Preferably, only the permanent magnets of the magnet arrangement intended for rotating the rotor are arranged on the rotor as permanent magnetic components or permanent magnets.

[0015] Between the permanent magnets of the magnetic arrangement, particularly between opposite sides of adjacent permanent magnets, angular distances and / or gaps and / or spaces are preferably present with respect to the axis of rotation. The angular distances with respect to the axis of rotation are, for example, at least 5°, preferably at least 10°, and particularly at least 15°. Thus, gaps are present between the permanent magnets, which negatively affects the quality of the rotating magnetic field acting on the sensor arrangement. However, due to the switching thresholds of the sensors, it is possible to eliminate or suppress any resulting discontinuities, steps, or jumps in the rotating magnetic field.

[0016] The permanent magnets are preferably plates, plate-shaped or in the form of discs.

[0017] It is advantageous if the permanent magnets and / or the rotor as a whole protrude in the direction of the sensor arrangement in front of the stator or an end face of the stator. This allows the magnetic field of the permanent magnets to be detected more effectively by the sensors.

[0018] Minimum distances are advantageous between the magnet arrangement and the sensor arrangement, i.e., between the facing sides of the rotor permanent magnets and the sensors, for example, a minimum distance of at least 0.4 mm, preferably at least 0.8 mm, and particularly at least 1 mm. The nominal minimum distance between the magnet arrangement and the sensor arrangement is, for example, 1 mm, whereby tolerances allow for distances between 0.4 mm and 1.6 mm.

[0019] While it is possible for the sensors of the sensor assembly to be individually or separately fixed to the stator or in relation to the stator, it is preferred that the sensors of the sensor assembly be arranged on a sensor carrier, for example, on a printed circuit board. The sensor carrier preferably has positive-locking contours for positive-locking attachment to the stator, for example, positive-locking projections, positive-locking recesses, or the like, and / or is frictionally attached to the stator, for example, by means of a clamping device.

[0020] It is particularly advantageous if the sensor carrier is designed for mounting on a motor cover or between a motor cover and a stator lamination stack. The motor cover is, for example, a so-called motor shield. The motor cover may, for example, have a receptacle for the sensor carrier, in particular a recess. The motor cover may, for example, have a pivot bearing for the motor shaft or a bearing receptacle for a pivot bearing. The motor cover can also form the sensor carrier itself, meaning that the sensors or the sensor assembly are mounted on the motor cover.

[0021] It is further advantageous that the sensor carrier has at least one positive-locking contour for mounting on or with respect to the stator such that the sensor carrier can be mounted on the stator or with respect to the stator with respect to the axis of rotation of the drive motor only in a single angular position or only in such angular positions in which a predetermined angular distance is provided between each sensor of the sensor arrangement and a coil of the stator coil arrangement arranged next to the sensor. Thus, several angular positions can certainly be provided in which the sensor carrier or the sensor arrangement can be arranged on the stator with respect to the axis of rotation. However, these angular positions are advantageously predetermined angular positions in which predetermined angular distances with respect to the axis of rotation are provided between the sensors of the sensor arrangement and the stator coils. Advantageously, the angular distance is zero.

[0022] A counter-positive locking contour for engagement with the positive locking contour of the sensor carrier can be arranged on the stator and / or a motor cover. The motor cover is preferably attachable to the stator in a single rotational angular position or in predetermined rotational angular positions, so that the sensor carrier, held on the motor cover in a predetermined angular position, can be mounted in a predetermined angular position relative to the stator. Preferably, there are multiple positive locking contours and counter-positive locking contours that have angular distances to each other relative to the axis of rotation of the drive motor, in particular equidistant angular distances.

[0023] It is advantageous if at least one sensor, preferably each sensor of the sensor arrangement, is arranged centrally with respect to the stator coil to which the sensor is assigned. However, it is also advantageously possible for at least one sensor, preferably each sensor of the sensor arrangement, to be arranged, so to speak, in a tooth stack and / or centrally between adjacent stator coils.

[0024] The switching thresholds can be directly integrated into the respective sensors, so that they change the digital value of their sensor signal or switching signal when a switching threshold is exceeded and / or fallen below. However, it is also possible for the evaluation unit to digitally change the value of the sensor signal or switching signal when a threshold is exceeded and / or fallen below.

[0025] An optimal configuration in practice provides switching thresholds of the following type: Each half-wave of the rotating magnetic field traverses a phase angle of 180°, while a full wave of the rotating magnetic field traverses a phase angle of 360°. A full wave contains two successive half-waves: a positive and a negative half-wave, or half-waves with opposite polarities, for example, a first and a second polarity. There is a zero crossing between a negative and a positive half-wave, or between half-waves with opposite polarities.

[0026] In a rotor with one pole pair (i.e., two magnetic poles), one full wave of the rotating magnetic field occurs at each sensor during one mechanical revolution of the rotor; in a rotor with two pole pairs, for example, two full waves occur. Insofar as the waves of the rotating magnetic field are described below, they are described in terms of electrical angles.

[0027] The switching thresholds of the sensors are advantageously selected such that the switching signal of a respective sensor exhibits a switching signal change at an electrical phase angle of approximately 30° or exactly 30° after a transition of a wave of the rotating magnetic field from a positive half-wave to a negative half-wave or from a negative half-wave to a positive half-wave. In other words, it can also be provided that the switching thresholds of the sensors are configured such that the switching signal of a respective sensor exhibits a switching signal change at a phase angle of approximately 30° after a transition of a wave of the rotating magnetic field from a half-wave with the first polarity to a half-wave with the second polarity.

[0028] A switching signal change, or a change in the switching signal, is, for example, a change from logic zero to logic one or vice versa. Certain tolerances regarding the 30° angle are possible. However, precise adjustment of switching thresholds is preferred to achieve the most accurate possible switching signal changes at phase angles of 30° after a transition of the rotating magnetic field wave from a first to a second polarity.

[0029] The above-mentioned switching thresholds allow the drive motor to be operated in opposite directions of rotation without any problems.

[0030] Furthermore, the selection of switching thresholds at exactly or approximately 30° allows the sensor arrangement to be operated without mechanical or electrical modification, even with a mechanically identical drive motor but different stator coil configurations (delta or star connection). This also enables different winding arrangements and / or different stator coil configurations.

[0031] Advantageously, the phase angle and / or the switching thresholds are set using the magnetic hysteresis of a respective sensor, for example, a Hall sensor. Preferably, the phase angle of approximately 30° and / or the switching thresholds are set using the magnetic hysteresis of a respective sensor.

[0032] The power supply unit preferably forms part of the drive motor. The drive motor and the power supply unit can also form a single system. In particular, a machine tool of the type mentioned above, for example a hand-held machine tool or a semi-stationary machine tool, comprises the drive motor and a power supply unit. The stator coil arrangement can, for example, be connected in a delta or star configuration and / or connected to the power supply unit.

[0033] The power supply device is preferably configured for block-type power supply to the stator coil assembly. The power supply device preferably comprises a bridge circuit for supplying power to the stator coil assembly.

[0034] Preferably, the power supply unit comprises a commutation table for a delta connection of the stator coil arrangement and a commutation table for a star connection of the stator coil arrangement. The commutation tables can, for example, be stored in a memory of the power supply unit. A program module of the power supply unit can be parameterized to access the appropriate commutation table for either the star or delta connection.

[0035] It is preferred if the delta connection is implemented when the drive motor is powered by a mobile energy storage device, such as a battery pack or accumulator pack. A machine tool with a drive motor according to the invention is therefore particularly preferred, the stator coil arrangement of which has a delta connection and is connected to a power supply unit that is powered by an electrical energy storage device. The machine tool thus has, for example, a power supply connection for the detachable arrangement of the electrical energy storage device. The energy storage device provides, for example, a DC voltage of 10.8 V, 12 V, 14 V, 18 V, 36 V, or the like, as the supply voltage for the power supply unit and thus the drive motor. Therefore, the energy storage device advantageously provides high currents at a comparatively low supply voltage. The machine tool is advantageously a screwdriving machine or a screwdriving device.

[0036] The star connection is preferred when the drive motor is powered by an AC power supply, for example, 120 V, 230 V, or the like. The AC power supply provides a relatively high supply voltage, so the power supply unit draws smaller currents from the AC power supply. The drive motor, with a stator coil arrangement connected in a star connection and linked to a power supply unit, is advantageously a component of a machine tool with a power supply connection for an AC power supply unit. For example, the machine tool has a connection cable for connecting to the AC power supply unit and / or a plug connector for connecting a power supply cable for the AC power supply unit.

[0037] Based on the switching signals of the sensor arrangement, the current supply device can control the stator coil arrangement in the sense of neutral commutation, but in principle also in the sense of pre-commutation or post-commutation.

[0038] Neutral commutation involves adjusting the voltages of the stator coils so that the rotating magnetic field generated by the stator coils is synchronous with or corresponds to the rotor position or angular position of the rotor.

[0039] Pre-commutation involves adjusting the voltages of the stator coils so that the rotating magnetic field generated by the stator coils precedes or leads the rotor position or angular position of the rotor.

[0040] A post-commutation therefore provides that the voltages of the stator coils are adjusted in such a way that the rotating magnetic field generated by the stator coils lags behind the rotor position or angular position of the rotor.

[0041] A preferred concept provides that the sensor arrangement generates the switching signals in a delta connection of the stator coil arrangement in the sense of neutral commutation. Advantageously, the sensor arrangement is positioned relative to the stator such that the sensors generate the switching signals in a delta connection of the stator coil arrangement in the sense of neutral commutation. This configuration is particularly advantageous when the drive motor or machine tool is powered by an energy storage device, which preferably provides a DC voltage in the range of 12 to 48 V. This configuration is especially advantageous when the drive motor is used in a machine tool where a high starting torque is desired, for example, in a design of the machine tool as a screwdriving machine.

[0042] Neutral commutation is achieved in particular by setting the switching thresholds of the sensors such that the sensors output a switching signal change at a phase angle of approximately 30° before and after a zero crossing of a wave of the rotating magnetic field.

[0043] Furthermore, it is possible for the sensor arrangement to generate the switching signals in a star connection of the stator coil arrangement, acting as a pre-commutation. It is advantageous that the sensor arrangement is positioned relative to the stator such that the sensors generate the switching signals in a star connection of the stator coil arrangement, acting as a pre-commutation. This configuration is particularly advantageous for a machine tool that is designed for electrical power supply via an AC power grid and has a suitable supply connection for this purpose. For example, this machine tool is a sawing machine in which a lower starting torque of the drive motor is acceptable because the working tool, for example, the saw blade, is first brought up to a predetermined speed before the working tool engages or cuts into the workpiece. The pre-commutation preferably corresponds electrically to approximately 30°.

[0044] However, it is also possible that the sensor arrangement is arranged in such a way with respect to the stator that the sensors generate the switching signals in the case of a star connection of the stator coil arrangement in the sense of neutral commutation, while in the case of a delta connection the switching signals are generated in the sense of post-commutation or pre-commutation.

[0045] It is possible that the waves measured by the sensors are solely those generated by the permanent magnets. In practice, however, there are superposition effects due to the rotating magnetic field generated by the stator coil arrangement. The rotating magnetic field measured by or acting upon the sensors contains, for example, a partial magnetic field generated by the stator coil arrangement and a partial magnetic field generated by the permanent magnets, with these partial fields superimposed on each other.

[0046] The rotor and / or the stator preferably comprise laminated cores. The laminated cores of the rotor and / or the stator are preferably made of laminated electrical steel or transformer steel.

[0047] The motor shaft passes, for example, through a shaft opening in a sheet metal stack that is held to the motor shaft.

[0048] An embodiment of the invention is explained below with reference to the drawing. Although the embodiment depicts a two-pole rotor, this does not limit the applicability of the invention. The principle can readily be implemented with rotors having additional poles, for example, four-pole or six-pole rotors, or rotors with a different magnet arrangement. The stator coil arrangement can also be modified. Likewise, the stator coil arrangement of the following embodiment can be connected or wired differently than in a delta or star connection, for example, combinations of star and delta connections, series connections, parallel connections, or the like.

[0049] They show: Figure 1 is an exploded view of a drive motor, which is shown from the side in Figure 2; Figure 3 is a longitudinal section through the drive motor according to the preceding figures; Figure 4 is a hand-held machine tool with a drive motor according to the preceding figures in the form of a mains-powered machine; Figure 5 is a hand-held machine tool in the form of a hand-held machine tool operated with a mobile energy storage device, and a drive motor according to Figures 1-3 Figure 6 shows an exploded view of a rotor and a sensor arrangement of the drive motor according to the preceding figures, Figure 7 shows a detail of the rotor and of permanent magnets on the rotor, approximately corresponding to a section D1 in Figure 6 Figure 8 shows a circuit diagram of the drive motor and its power supply unit, Figure 9 shows a schematic front view of the drive motor and the sensor arrangement, Figure 10 shows a path through the sensor arrangement of the drive motor to Figure 9measurable magnetic fields, Figure 11 a schematic representation of switching signals of the sensor arrangement of the drive motor according to the preceding figures, Figure 12 a commutation table for a stator coil arrangement of the drive motor according to the preceding figures, which is connected in star connection to the power supply device, Figure 13 a commutation table for a stator coil arrangement of the drive motor according to the preceding figures, which is connected in delta connection to the power supply device, Figure 14 phase voltages of the stator coil arrangement in star connection, which correspond to a back EMF (EMF = electromotive force), Figure 15 by the power supply device of the drive motor at the stator coil arrangement in star connection accordingly Figure 14 Set block voltage waveforms synoptically with ideal voltage waveforms, and Figure 16 waveforms of a back EMF of the stator coil arrangement in delta connection and a single exemplary block voltage waveform.

[0050] A drive motor 10 has a stator 20 on which a rotor 30 is rotatably mounted about a rotational axis D. The stator 20 has a stator lamination stack 21 with laminations 22. The lamination stack 21 has a receptacle 23 in which the rotor 30 is received. Motor covers 50 and 40 are arranged on opposite end faces 24 and 25, respectively, which close the receptacle 23.

[0051] Furthermore, the stator 20 carries a stator coil arrangement 26 with stator coils 27A, 27B and 27C.

[0052] The rotor 30 has a rotor lamination stack 31, which is mounted in the receptacle 23. The lamination stack 31 comprises laminations 32 stacked on top of each other. The lamination stack 31 is penetrated by a motor shaft 33, which is rotatably mounted relative to the stator 20 about the axis of rotation D by means of a bearing arrangement 47A. The end faces 34 and 35 of the rotor 30 face the motor covers 50 and 40.

[0053] The rotor sheet metal assembly 31 is provided with magnet receptacles 36 for permanent magnets 38 of a magnet arrangement 37. The permanent magnets 38 are inserted into the magnet receptacles 36, for example, by means of a plug-in assembly with a force direction SR.

[0054] The permanent magnets 38 are designed in a plate-like form and have, for example, flat sides 38F, between which narrow sides 38S extend. With their narrow sides 38S, the permanent magnets 38 are arranged next to each other, so that a ring-shaped configuration is formed.

[0055] However, there are 38 angular distances W between the permanent magnets. No permanent magnet is located within any of these angular distances W.

[0056] The flat sides 38F, for example, are orthogonal to radius lines extending away from the axis of rotation D.

[0057] The motor covers 40, 50 have bearing receptacles 43, 53 in which rotary bearings 47, 57 of the bearing arrangement 47A are received and which rotatably support the motor shaft 33. The rotary bearings 47, 57 are, for example, rolling bearings, in particular ball bearings. The motor shaft 33 projects, for example, on one or two sides in front of the stator 30 or the motor covers 40, 50; in the exemplary embodiment, even on two sides, namely on end faces or front faces 45, 54 of the motor covers 40, 50. End faces 44 and 55 of the motor covers 40 and 50 face the stator 20 and close it off at the end face.

[0058] The stator coil arrangement 26 is connected to a power supply device 85 by means of terminals 28A, 28B, 28C which are connected to the stator coils 27A, 27B, 27C.

[0059] The current supply device 85 supplies current to the stator coils 27 in such a way that a rotating field is created which, in interaction with the magnet arrangement 37, drives the rotor 30 rotationally around the axis of rotation D.

[0060] The power supply unit 85, for example, includes a control unit 80 with which a bridge circuit 86 can be controlled. The bridge circuit 86 comprises upper switches SA1, SB1, SC1 and lower switches SA2, SB2, SC2, wherein the upper switches SA1, SB1, SC1 are connected to a supply potential V1 and the lower switches SA2, SB2, SC2 are connected to a potential V0, for example, ground. A connecting line LA, LB, and LC is connected between each of the respective upper and lower switches SA1, SA2 or SB1, SB2, or SC1 and SC2, and these lines are connected to terminals 28A-28C.

[0061] To optimally control the stator coils 27, the controller 80 requires information about the respective rotational position of the rotor 30 relative to the stator 20 with respect to the axis of rotation D. A sensor arrangement 60 is provided for this purpose. The sensor arrangement 60 comprises a sensor carrier 61, for example, a printed circuit board 62, which is stationary relative to the stator 20. For example, the sensor carrier 61 is sandwiched between the motor cover 40 and the stator 20.

[0062] The sensor carrier 61 is received in a receptacle 41 of the motor cover 40. The motor cover has positive-locking recesses 42, i.e., mating positive-locking contours 42A, on its radial outer circumference, into which positive-locking projections 63, i.e., positive-locking contours 63A, of the sensor carrier 61 engage. The positive-locking projections are, for example, star-shaped, so that they fit positively into the complementary positive-locking recesses 42. This secures the sensor carrier 61 against rotation about the axis of rotation D in the receptacle 41.

[0063] Further torsionally rigid support is provided by additional positive locking contours, namely, for example, positive locking receptacles 66 in the form of plug-in receptacles, into which positive locking projections 46, which extend from the motor cover 40 towards the receptacle 41, engage (i.e., counter-positive locking contours). The positive locking projections 63 and positive locking receptacles 66 are angularly spaced with respect to the axis of rotation D, as are the complementary positive locking receptacles 42 and positive locking projections 46 of the motor cover 40 that retain these positive locking elements.

[0064] The end face 35 of the rotor 30 projects in front of the end face 25 of the stator 20 by a predetermined dimension 39, so that the magnetic field and thus the magnetic field of the permanent magnets 38 sensors 67A, 67B and 67C of the sensor arrangement 60 can penetrate better.

[0065] The sensors 67A, 67B, and 67C are advantageously arranged on the end face 64 of the sensor carrier 61 facing the rotor 30. Other electrical components, such as resistors and the like, can also be arranged there. The sensors 67 are, for example, Hall sensors with preset or adjustable switching thresholds. However, it is also possible for the sensors 67 to be sensors that generate analog measurement signals corresponding to the magnetic field acting upon them, which are then evaluated by an evaluation device 70, for example, a threshold circuit, of the sensor arrangement 60.

[0066] The sensor assembly 60 has a connection device 68 for connection to the controller 80. The connection device 68 includes, for example, a plug 69, which is connected via lines 69L to the sensor carrier 61 and the electrical components arranged thereon, such as the sensors 67. The lines 69L accordingly enable the transmission of switching signals SA, SB, and SC from the sensors 67A, 67B, 67C or the evaluation unit 70. As mentioned, it is possible that the sensors 67A, 67B, and 67C themselves generate digital switching signals. However, it is also possible that the evaluation unit 70 can generate the digital switching signals SA, SB, and SC based on analog measurement signals or sensor signals from the sensors 67A, 67B, and 67C. However, it is also conceivable that the sensors 67A, 67B, 67C transmit analog measurement signals to the control unit 80, which generates the digital switching signals 67A, 67B, 67C from them.The control unit 80 thus forms, so to speak, an evaluation device for the sensor arrangement 60 or a component of the sensor arrangement 60.

[0067] The controller 80 comprises a processor 81, which communicates with a memory 82 containing a control program 83 for controlling the power supply unit 85. The power supply unit 85, in particular the bridge circuit 86, represents power electronics that can be controlled by the controller 80 via an interface 84. Switches SA1-SC2, for example, are power transistors, etc. This is generally known.

[0068] The stator coil arrangement 26 can, for example, be connected to the power supply unit 85 in a delta connection. In this case, the stator coils 27 are designated 27Ad, 27Bd, and 27Cd. In the star connection shown in dashed lines, however, the stator coils 27 are designated 27As, 27Bs, and 27Cs.

[0069] The delta connection is advantageous, for example, for a hand-held machine tool 80, which can be supplied with an electrical supply voltage P2 by an electrical energy storage device 206, for example a battery pack.

[0070] The star connection, on the other hand, is suitable, for example, for a machine tool 300, such as a circular saw, which can be supplied by an electrical power supply network EV with a supply voltage P1.

[0071] The hand-held power tools 200, 300 have housings 203, 303 in which a drive motor 10 is arranged for driving a tool holder 201, 301. The tool holder 201, 301 serves for the detachable fastening of a working tool 202, 302, for example a drill or screwdriver 202 or a saw 302.

[0072] By means of a switch 204 or 304, the power supply devices 85 of the hand-held machine tools 200 and 300 can be activated in order to switch the drive motor 10 on or off and / or to change its speed and / or its power.

[0073] The hand-held machine tool 200, for example a screwdriver or drill, has a supply connection 205 for the energy storage device 206, for example with plug contacts, a plug interface or the like.

[0074] The hand-held machine tool 300, on the other hand, has a supply connection 305, for example a power cable with a power plug, for plugging into a connection device that is connected to the supply network EV.

[0075] In Figure 9 The drive motor 10 is shown schematically. It can be seen that each of the stator coils 27A, 27B and 27C is assigned a sensor 27A, 27B and 27C, respectively, at the pole center.

[0076] The stator coil arrangement 26 is connected in a multi-phase configuration, for example in a three-phase configuration.

[0077] The rotor 30, for example, is a two-pole rotor, wherein opposing permanent magnets 38 have the same polarity radially outwards with respect to the axis of rotation D, i.e., in the direction of an air gap between rotor 30 and stator 20, while permanent magnets 38 offset by 90 degrees with respect to the axis of rotation D have the opposite polarity, which is indicated by the reference symbols 38S (e.g., magnetic south pole) and 38N (e.g., magnetic north pole) for the permanent magnets 38 in Figure 9 as indicated.

[0078] In Figure 10Magnetic field profiles are depicted, namely an ideal field profile FBI, which originates quasi-sinusoidally from a zero position (phase angle γ = 0). Starting from this zero position, a clockwise rotation RL and a counterclockwise rotation LL of the drive motor 10, and the resulting temporal evolution of waves in the rotating magnetic field, are shown. The rotating field is depicted for a stationary observer located at the stator 20, in this case the respective sensor 67, after a rotation of γ = X° and relative to the number of pole pairs of the rotor 30.

[0079] The ideal field pattern FBI is given by a virtually ideal rotor 30, in which the permanent magnets 38 are arranged directly next to each other, i.e., they have no angular distances and / or there is no influence from the rotating field emanating from the stator coil arrangement 26. With ideal waves, e.g., of the type FBI, of the rotating magnetic field, the sensors 67A, 67B, and 67C switch quasi-ideal switching signals SAI, SBI, and SCI, respectively, at the zero crossing of the ideal waves of the rotating magnetic field, i.e., at a switching threshold N or a zero crossing N according to Figure 10 .

[0080] However, magnetic sensors, such as Hall sensors, exhibit a characteristic called hysteresis. As will become clearer below, this hysteresis is optimally adjusted and utilized by setting an upper switching threshold SH and a lower switching threshold SL on the sensors 67 or the evaluation unit 70. The upper and lower switching thresholds SH and SL are symmetrical.

[0081] The angular distances between the permanent magnets 38, however, result in a real course of the waves of the rotating magnetic field, which is detected by the sensors 67, for example real courses of the rotating fields FA, FB and FC, which are detected by or act upon the sensors 67A, 67B, 67C.

[0082] However, additional influences from the current flow to the stator coils 27A-27C and the resulting field also come into play, meaning that the waves of the rotating magnetic field detected by sensors 67A, 67B, and 67C can exhibit maximum or minimum profiles. For example, maximum and minimum profiles FBO and FBU of the rotating magnetic field acting on sensor 67B are possible.

[0083] Between continuously rising edges AF or continuously falling edges DF of the upper and lower half-waves HO and HU of the rotating field FA, FB, FC, there are transition sections UG with steps ST where the waves of the rotating magnetic field FB are not continuous. This, so to speak, indifferent region or the transition sections UG are effectively masked by the upper and lower switching thresholds SH and SL of the sensors 67A, 67B, 67C. Accordingly, the upper switching threshold SH and the lower switching threshold SL are selected and / or designed.

[0084] The following example of sensor 67B will illustrate this more clearly: When rotor 30 rotates clockwise (RL) starting from a phase angle γ = 0°, the rotating magnetic field acting on and / or detected by sensor 67B initially exhibits a positive or upper half-wave HO. At the switching threshold N or zero crossing N, it changes its polarity and becomes a lower half-wave HU. At time T1R, the lower half-wave HU passes through the lower switching threshold SL, which triggers a switching of sensor 67B, i.e., a switching signal change SW1, for example, a change from logic one to logic zero.

[0085] After the rotating field FB has passed through its lower maximum, so to speak, at a phase angle γ = 180°, the lower half-wave HU transitions into an upper half-wave HO at a phase angle of γ = 270° and exceeds the upper switching threshold SH at a time T2R, so that the sensor 67B is switched again, so to speak, and generates a switching signal change SW2, for example from logic zero to logic one.

[0086] This scheme also works for the counterclockwise rotation LL of the rotor 30: again starting from the positive or upper half-wave HO at the phase angle γ = 0°, the rotating field FB transitions into the negative half-wave HU and falls below the lower switching threshold SL at a time T1L, so that the sensor 67B changes the level of the switching signal SB from logic one to logic zero, i.e., performs a switching signal change SW2.

[0087] During the further counterclockwise rotation LL of the rotor 30, the rotating field FB first passes through a minimum and then rises again and passes through the switching threshold N or the zero crossing N and subsequently, at a phase angle of γ = -300°, the upper switching threshold SH, which leads to a switching signal change SW1 at a time T2L.

[0088] In Figure 12 An exemplary commutation table KS for a star-connected energizing of the stator coil arrangement 26 is shown. Figure 13 An example commutation table KD for a delta connection is shown. The commutation tables KS and KD are stored, for example, in memory 82 of the controller 80 and can be used selectively by program 83 to control the bridge circuit 86, whereby program 83 uses commutation table KS for the stator coil arrangement 26 in star connection and commutation table KD for the stator coil arrangement 26 in delta connection.

[0089] In both commutation tables KS and KD, sectors S with values ​​1 to 6 are specified, which result from a binary addition of the signal levels of the switching signals SA, SB and SC, where the switching signal SA with the binary value 1, the switching signal SB with the binary value 2 and the switching signal SC with the binary value 4 contribute to the respective value 1 to 6 of the sectors S.

[0090] In the left-hand column of commutation tables KS and KD, the electrical potentials that the power supply device 26 provides to the connecting lines LA, LB, and LC for the stator coil assembly 26 are designated LA, LB, and LC, respectively. In commutation tables KS and KD, "+" indicates that a respective connecting line LA, LB, or LC is connected to the supply potential V1, and "-" indicates that a respective connecting line LA, LB, or LC is connected to the potential V0, for example, ground. If a respective connecting line LA, LB, or LC is not connected to either potential V1 or V0, "0" is indicated in commutation table KS or KD.

[0091] In Figure 14The back electromotive force (EMF) applied to the star-connected stator coils 27As, 27Bs, and 27Cs is given in the form of voltages USA, USB, and USC (EMF = electromotive force) or, in English, BEMF (= back electromotive force), which are established when the rotor 30 rotates. Ideally, these voltages USA, USB, and USC correspond to voltages USAs, USBs, and USCs, as e.g., in Figure 15As shown, the voltages USAs, USBs, and USCs are adjustable via the current-generating device 85. Ideally, the voltages USAs, USBs, and USCs applied to the stator coils 27As, 27Bs, and 27Cs are sinusoidal, as set by the current-generating device 85. However, in practice, the current-generating device 85 advantageously performs block current generation, i.e., it sets the voltages at the stator coils 27As, 27Bs, and 27Cs as block voltage waveforms USAb, USBb, and USCb, so that the voltages USAs, USBs, and USCs are approximated. The circuit diagram for generating the block phase voltages USAb, USBb, and USCb is defined by the commutation tables KS. Sectors S with values ​​1 to 6 are shown synoptically. It can be seen that pre-commutation takes place in a star connection.

[0092] In Figure 16The back EMF voltages UDA, UDB, and UDC applied to the stator coils 27Ad, 27Bd, and 27Cd connected in a delta configuration are shown, which are established when the rotor 30 rotates. Ideally, these voltages UDA, UDB, and UDC correspond to the voltages that the current-energizing device 85 would ideally set as desired voltage profiles; that is, a voltage UDAs set by the current-energizing device 85 at the stator coil 27Ad corresponds to the voltage UDA. As already discussed in connection with the star connection and the Figures 14 and 15 As explained, the current-energizing device 85 sets block voltages based on the commutation table KD, for example, a block voltage UDAb. For the sake of simplicity, the other block-delta voltages that the current-energizing device 85 sets at the stator coils 27Bd and 27Cd based on the commutation table are not shown in Figure 16The diagram does not show the sectors S with values ​​1 to 6, but these are shown. It becomes apparent that in delta connection, a virtually ideal or neutral commutation takes place. At the respective switching or commutation times, the maximum voltage is applied to the stator coils 27Ad, 27Bd, and 27Cd, resulting in high torque and thus high power output from the drive motor ten. Therefore, particularly in screwdrivers that are intended to operate with high starting torque even from a standstill, ideal or neutral commutation is achievable.

Claims

1. A drive motor for a vacuum cleaner or a machine tool, in the form of a hand-held machine tool (200, 300) or a semi-stationary machine tool, wherein the drive motor (10) comprises a stator (20) with a stator coil arrangement (26), and a rotor (30) with a motor shaft (33) which is mounted on the stator (20) or with respect to the stator using a bearing arrangement (47), so as to be able to rotate about an axis of rotation (D), wherein the rotor (30) comprises a magnet arrangement (37) with permanent magnets (38) arranged annularly about the axis of rotation (D), wherein a sensor arrangement (60) is arranged in a stationary manner with respect to the stator (20) in order to detect a respective angle of rotation position of the rotor (30) with respect to the stator (20), said sensor arrangement comprising at least two sensors which are configured to generate, in particular, digital switching signals (SA, SB, SC) for an energization device (85) for energizing the stator coil arrangement (26) so that the rotor (30) can be driven in rotation about the axis of rotation (D) through energization of the stator coil arrangement (26), characterized in that the at least two sensors (67A, 67b, 67C) are configured to detect two waves of a magnetic rotating field (FB) of the rotor (30), said waves being phase-shifted about an angle of rotation, wherein the sensors (67A, 67b, 67C) generate the switching signals (SA, SB, SC) in a manner dependent on a wave of the magnetic rotating field (FB) exceeding or undershooting a switching threshold (SH, SL) of the sensor (67A, 67b, 67C), said wave respectively passing through the sensor (67A, 67b, 67C), and in that the permanent magnets (38) of the magnet arrangement (37) comprise angular spacings from one another with respect to the axis of rotation (D), so that the waves of the magnetic rotating field (FB) comprise, at the location of the respective sensor (67A, 67b, 67C), continuous, in particular approximately sinusoidal, half-waves (HO, HU) with vertices between continuously rising and falling edges (AF, DF), wherein the waves in the transition sections (UG) between respectively successive half-waves (HO, HU) comprise a different polarity, wherein the waves in the transition sections (UG) comprise at least one step (ST) or a jump or an unevenness, and in that the switching thresholds (SH, SL) of the sensors (67A, 67b, 67C) are arranged in the region of the continuously rising or falling edges (AF, DF) of the half-waves (HO, HU).

2. The drive motor according to claim 1, characterized in that the permanent magnets (38) of the magnet arrangement (37) are provided and configured for driving in rotation of the rotor (30) in cooperation with the stator coil arrangement (26).

3. The drive motor according to claim 1 or 2, characterized in that no magnetic encoder provided exclusively for actuating the sensor arrangement (60) and / or permanent magnets (38) of the magnet arrangement (37) provided exclusively for the driving in rotation of the rotor (30) is / are arranged on the rotor (30) as permanent magnetic (38) components or permanent magnets (38).

4. The drive motor according to any one of the preceding claims, characterized in that, between mutually facing sides of adjacent permanent magnets (38) of the magnet arrangement (37), there are angular spacings, in particular angular spacings of at least 5°, preferably at least 10°, in particular at least 15° with respect to the axis of rotation.

5. The drive motor according to any one of the preceding claims, characterized in that the magnet arrangement (37), in particular the rotor (30) as a whole, protrudes in front of the stator (20) in the direction of the sensor arrangement (60) and / or in that, between the magnet arrangement (37) and the sensor arrangement (60), a spacing of at least 0.4 mm, in particular at least 0.8 mm, preferably at least 1 mm is provided.

6. The drive motor according to any one of the preceding claims, characterized in that the sensor arrangement (60) comprises a sensor support (61), in particular in the form of a circuit board (62), on which the sensors (67A, 67b, 67C) are arranged.

7. The drive motor according to claim 6, characterized in that the sensor support (61) is configured to be mounted on a motor cover (50) or between a motor cover (50) and a stator sheet stack (21) of the stator (20) or the motor cover (50) forms the sensor support (61) and / or in that the sensor support (61) comprises at least one positive locking contour (63A) for mounting on the stator (20) or with respect to the stator (20), in such a manner that the sensor support (61) with respect to the stator (20) can be mounted in only one angular position with respect to the axis of rotation (D) of the drive motor (10) or only in such angular positions in which, between each sensor (67A, 67b, 67C) of the sensor arrangement (60) and a coil (26A, 26B, 26C) of the stator coils which is arranged next to the sensor (67A, 67b, 67C), a predetermined angular spacing is provided.

8. The drive motor according to any one of the preceding claims, characterized in that at least one sensor (67A, 67b, 67C) or each sensor (67A, 67b, 67C) of the sensor arrangement (60) in each case is arranged centrally between adjacent stator coils (27A, 27B, 27C) or centrally with respect to the stator coil (27A, 27B, 27C) which is associated with the sensor (67A, 67b, 67C).

9. The drive motor according to any one of the preceding claims, characterized in that a full-wave of the magnetic rotating field (FB) includes half-waves (HO, HU) of different polarity, which each pass through a phase angle of 180°, and in that the switching thresholds (SH, SL) are provided in such a manner that the switching signal (SA, SB, SC) of a respective sensor (67A, 67b, 67C) at a phase angle of approximately 30° after a transition of a wave of the magnetic rotating field (FB) from a half-wave (HO, HU) of one polarity to a half-wave (HO, HU) of the other polarity comprises a switching signal change (SW1, SW2).

10. The drive motor according to any one of the preceding claims, characterized in that the phase angle of approximately 30° and / or the switching thresholds (SH, SL) are set using a magnetic hysteresis of a respective sensor (67A, 67b, 67C).

11. The drive motor (10) according to any one of the preceding claims, characterized in that the sensor arrangement (60) is arranged with respect to the stator (20) in such a manner that the sensors (67A, 67b, 67C) generate the switching signals (SA, SB, SC) in a delta connection of the stator coil arrangement (26) for the purpose of a neutral commutation, wherein it is advantageously provided that the neutral commutation is brought about in that the switching thresholds of the sensors (67A, 67b, 67C) are set up so that the sensors (67A, 67b, 67C) at a phase angle of approximately 30° before and / or after a zero-crossing of a wave of the magnetic rotating field (FB) output a switching signal change (SW1, SW2).

12. The drive motor according to any one of the preceding claims, characterized in that the sensor arrangement (60) is arranged with respect to the stator (20) in such a manner that the sensors (67A, 67b, 67C) generate the switching signals (SA, SB, SC) in a star connection of the stator coil arrangement (26) for the purpose of a precommutation, wherein it is advantageously provided that the precommutation is electrically exact or corresponds to approximately 30°.

13. The drive motor according to any one of the preceding claims, characterized in that the energization device (85) comprises a commutation table for the stator coil arrangement (26) in a delta connection and / or a commutation table for the stator coil arrangement (26) in a star connection or alternatively can be parametrized with commutation tables for a delta connection and a star connection.

14. The drive motor according to any one of the preceding claims, characterized in that the magnetic rotating field (FB) acting on the sensors (67A, 67b, 67C) contains a magnetic subfield which is generated by the stator coil arrangement (26) and contains a magnetic subfield which is generated by the permanent magnets (38), wherein the subfields overlap one another.

15. A machine tool, in particular a hand-held machine tool (200, 300) or a semi-stationary machine tool, with a drive motor (10) according to any one of the preceding claims or an energization device (85) for the energization of the drive motor, wherein it is advantageously provided that the stator coil arrangement (26) of the drive motor (10) is connected in a delta connection to the energization device (85), and the machine tool comprises a supply connection (205) for connecting an electric DC voltage energy storage (206), or in that the stator coil arrangement (26) of the drive motor (10) is connected in a star connection to the energization device (85), and the machine tool comprises a supply connection (305) for an electric AC voltage network (305).