Arrangement for determining the angular position of a shaft and electric motor

Abstract

Arrangement for determining the angular position of a shaft, which is mounted in a housing part with at least one bearing, where a fan wheel is non-rotatably connected to the shaft, wherein a printed circuit board is attached to the housing part, in particular wherein the normal direction of the printed circuit board is aligned parallel to the shaft axis, in particular wherein the circuit board is arranged between a housing part and the fan wheel, where - magnetized areas, in particular a pole disk, are provided on the side of the fan wheel facing the circuit board, which can be detected by sensors arranged on the circuit board, so that the angle value of the shaft can be detected, - another permanent magnet is arranged on the fan wheel, to which a sensor for detecting the number of revolutions is assigned on the circuit board, characterized by the fact that a rotational acceleration sensor, in particular a Ferraris sensor, is connected to the circuit board, which comprises an electrically conductive ring that is non-rotatably connected to the fan wheel, wherein the values ​​recorded by the sensors, i.e., respective angle values, rotational acceleration values ​​and revolutions per minute values, are transmitted via the same digital communication interface to another electronic circuit, such as an inverter and / or higher-level control system, the sensors are connected to an electronic circuit which is connected to the communication interface, wherein at least parts of the communication interface, the sensors and the electronic circuit are arranged on the printed circuit board, wherein an evaluation electronics is arranged on the circuit board, to which the sensor signals are supplied, and the evaluation electronics are designed such that - an angle value for the angular position of the fan wheel, - a rotational speed value of the fan wheel and - a rotational acceleration value of the fan wheel is determined wherein the communication interface is connected to a control unit of an inverter which supplies an electric motor, whose rotor shaft is the shaft to which, in particular, a detected motor current value is supplied and which provides a motor voltage, the recorded angle values ​​and rotational acceleration values ​​are fed to the control unit, where a temperature sensor is additionally arranged on the circuit board, the measured value of which is also transmitted via the communication interface, wherein the shaft is arranged in a motor and in the motor, in particular in the stator windings of the motor, a means for detecting the motor temperature and / or in the motor a means for detecting the torque transmitted by the shaft is arranged, wherein the recorded values ​​are fed to the electronic circuit arranged on the printed circuit board via galvanic isolation, in particular wherein the recorded values ​​are also transmitted to the further electronic circuit via the same digital interface.

Description

[0001] The invention relates to an arrangement for determining the angular position of a shaft and an electric motor.

[0002] In electric motors, it is known to arrange an angle sensor on the B-side of the rotor shaft, i.e. at an axial end area, which, however, has its own rotor shaft, which must be connected to the rotor shaft of the electric motor via a coupling.

[0003] From DE 10 2009 023 691 A1 an arrangement for determining the angular position of a shaft is known.

[0004] An electric motor is known from DE 10 2008 022 369 A1.

[0005] A direct drive built-in motor with special sensor mounting is known from DE 10 2006 010 198 B4.

[0006] A sensor arrangement is known from the publication “ACC 93, ACC 94, Ferraris acceleration sensor, Hübner Elektromaschinen GmbH, Berlin, 2007”.

[0007] From DE 10 2008 010 913 A1, an electric motor is known as the closest state of the art.

[0008] From EP 1 222 471 B1 a sensor system with an acceleration sensor and a position sensor is known.

[0009] An encapsulated measuring device is known from DE 102 43 177 A1.

[0010] The invention is therefore based on the object of developing an electric motor that is as compact as possible.

[0011] According to the invention, the object is achieved in the arrangement according to the features specified in claim 1 and in the electric motor according to the features specified in claim 11.

[0012] Important features of the invention in the arrangement for determining the angular position of a shaft are that the shaft is mounted in a housing part with at least one bearing, a fan wheel is connected to the shaft in a rotationally fixed manner, wherein a printed circuit board is attached to the housing part, in particular wherein the normal direction of the printed circuit board is aligned parallel to the shaft axis, wherein magnetized areas, in particular a pole disc, are provided on the side of the fan wheel facing the circuit board, which can be detected by sensors arranged on the circuit board, wherein the magnetized areas form three concentric tracks and each track is assigned at least one sensor on the circuit board, wherein in each track in the circumferential direction the axially executed magnetization direction is executed alternately, in particular a north pole area magnetized in the axial direction is followed by a south pole area, - magnetised areas, in particular a pole disc, are provided on the side of the fan wheel facing the circuit board, which can be detected by sensors arranged on the circuit board, so that the angle value of the shaft can be detected, - another permanent magnet is arranged on the fan wheel, to which a sensor for detecting the number of revolutions is assigned on the circuit board, - a rotational acceleration sensor, in particular a Ferraris sensor, is connected to the circuit board, which comprises an electrically conductive ring which is connected to the fan wheel in a rotationally fixed manner, wherein the values ​​detected by the sensors, in particular angle value, rotational acceleration value and revolution number value, are transmitted via the same communication interface, in particular via the same digital communication interface, to another electronic circuit, such as a converter and / or higher-level control.

[0013] The advantage here is that the electric motor can be designed compactly, a high angular resolution can be achieved after interpolation, and as few additional parts as possible are required. This is because the pole disk can be attached directly to the fan impeller. High resolution is achieved thanks to the multiple tracks of magnetized material. Furthermore, a large number of values ​​can be transmitted via the communication interface and thus fed to the same control unit without significant additional effort. This, in turn, allows for improved control.

[0014] A particularly advantageous feature is that all sensors can be arranged on a single circuit board, meaning the fan only needs to be equipped with correspondingly oppositely arranged magnets and / or magnetized areas. The sensors, or their associated permanent magnets or magnetized areas on the fan, can then be arranged at different radial distances.

[0015] In an advantageous embodiment, an energy storage device is arranged on the circuit board to power an electronic component in the event of a failure of the supply voltage assigned to the electronic circuit arranged on the circuit board. This is advantageous because a mains-independent energy source is available, thus allowing the entire rotational speed to be detected from assembly and production onward.

[0016] In an advantageous embodiment, the ring of the angular acceleration sensor is integrally connected to the fan wheel. This is advantageous because the angular acceleration can be detected on the metallic ring, while the fan can be constructed essentially from a non-electrically conductive material.

[0017] According to the invention, the sensors and are connected to an electronic circuit which is connected to the communication interface, wherein at least parts of the communication interface, the sensors and the electronic circuit are arranged on the circuit board, in particular, wherein an evaluation electronics is arranged on the circuit board, to which the sensor signals are fed and the evaluation electronics is designed in such a way that - an angle value for the angular position of the fan wheel, - a rotational speed value of the fan wheel and - a rotational acceleration value of the fan wheel is determined. This is advantageous because the sensors and components can be quickly and easily mounted on the circuit board, meaning that a sensor arrangement for detecting the three values ​​and the associated evaluation requires the same axial space as a sensor arrangement with only a single detected physical value. Advantageously, the data is transmitted via a single interface, particularly digitally. This enables particularly effective and compact production of the inventive design.

[0018] In an advantageous embodiment, the communication interface comprises at least one interface and / or a connector part. The advantage here is that the interface can be manufactured easily.

[0019] According to the invention, the communication interface is connected to a control unit of a converter that powers an electric motor whose rotor shaft is the shaft, in particular to which a detected motor current value is supplied and which provides a motor voltage. In particular, the detected angle values ​​and angular acceleration values ​​are supplied to the control unit. The advantage of this is that improved control behavior can be achieved. This is because supplying the angular acceleration in addition to the angle value supports the control with a physically real and detected value.

[0020] In an advantageous embodiment, the cooling air flow generated by the fan wheel cools the housing part, in particular, the fan wheel being a radial fan wheel, and the generated radial cooling air flow being deflected in a substantially axial direction by a fan cover provided on the housing part. This is advantageous in that a particularly simple fan wheel can be used, and the cooling air flow can be deflected by means of the fan cover, which is necessary anyway for safety reasons.

[0021] In an advantageous embodiment, the tracks are applied and / or realized in a disk, in particular a pole disk, made of ferrite material. The advantage here is that a cost-effective material is used.

[0022] In an advantageous embodiment, the period lengths of the respective magnetization curve provided within the respective track in the circumferential direction are assigned according to the vernier principle. This allows for a unique assignment of the sensor signals or sensor signal distribution to the absolute angular position of the fan wheel.

[0023] In an advantageous embodiment, three tracks are provided, whereby the number of north pole areas - in a first track 2^N, - in a second track 2^N - 1, - in a third track, 2^N - 2^(N / 2), where N is an integer. The advantage here is that a simple vernier principle can be applied, thus enabling a unique determination of the angular position using the three sensor signals.

[0024] In an advantageous embodiment, three tracks are provided, whereby the number of north pole areas - in a first track 10 * N, - in a second track 10 * N - 1, - in a third track, 9 * N, where N is an integer. The advantage here is that a simple vernier principle can be applied, thus enabling a unique determination of the angular position using the three sensor signals.

[0025] In an advantageous embodiment, the magnetization direction in each track is axial and has a sinusoidal magnitude in the circumferential direction. This is advantageous in that high angular resolution can be achieved.

[0026] In an advantageous embodiment, at least two sensors are assigned to each track, particularly for differential detection of the magnetization pattern in the circumferential direction. This has the advantage that homogeneous interference fields do not have a disruptive effect.

[0027] In an advantageous embodiment, the housing part for a magnetic field-generating device, such as the stator winding of an electric motor and / or the brake coil winding of an electromagnetically actuated brake, at least partially forms the housing. This is advantageous in that a magnetic field shielding effect can be achieved by the housing part if it is made of aluminum or steel, with low-frequency fields being better shielded by steel, and higher-frequency alternating fields being better shielded by aluminum.

[0028] In an advantageous embodiment, a means for shielding magnetic fields is provided between the housing part and the sensors. This has the advantage of allowing interference to be easily eliminated.

[0029] In an advantageous embodiment, the sensors are Hall sensors. This allows for the use of simple, cost-effective sensors.

[0030] In an advantageous embodiment, evaluation electronics are arranged on the circuit board, to which the sensor signals are fed. The evaluation electronics are designed to determine an angle value for the angular position of the fan wheel. This is advantageous because it enables a unique determination of the angle.

[0031] Important features of the electric motor are that the shaft is the rotor shaft of the electric motor and the fan wheel is arranged on the rotor shaft.

[0032] The advantage here is that a compact drive is created whose angular position can be determined unambiguously thanks to the principle of magnetic detection of multiple tracks. Unlike other principles, this principle is resistant to many disturbances, such as the effects of light, heat, or even water.

[0033] Further advantages arise from the subclaims. List of reference symbols 1 housing part, especially bearing shield 2 rotor shaft 3 Fan cover 4 fan wheel 5 Printed circuit board, including sensors 6 Pole disc 9 Permanent magnet 10 Battery 11 Shielding 12 pulse wire or microgenerator 26 Excitation winding 27 Eddy current ring 28 pickup winding The invention will now be explained in more detail with the aid of illustrations:

[0034] In the Fig. 1 shows a partially schematic representation of a device according to the invention.

[0035] This is an electric machine, in particular an electric motor, which comprises a housing part 1, in particular a bearing plate, in which at least one bearing is provided for supporting the rotor shaft 2 of the machine.

[0036] At the axial end of the rotor shaft 2, a fan impeller 4 is connected to the rotor shaft 2 in a rotationally fixed manner, so that the cooling air flow driven by the fan impeller 4 flows past the housing part 1 and thus serves to cool the motor, in particular the stator. The stator is located on the side of the housing part axially facing away from the fan impeller. The stator comprises stator windings that generate a rotating field and thus cause a strong magnetic field.

[0037] The fan wheel 4 is surrounded by a fan cover 3, allowing for easy control, particularly redirection, of the cooling air flow. The fan cover 3 is attached to the housing part 1.

[0038] Despite the shielding effect of the housing part 1, which is preferably made of cast steel or aluminum, part of the magnetic field of the stator or a brake coil enters the area of ​​the fan wheel.

[0039] The fan wheel 4 has a magnetized pole disk on its side facing the housing part 1. There are at least two tracks running in the direction of rotation, with the magnetization alternating in the circumferential direction. Each track therefore has a constant radial distance from the axis of the rotor shaft. In the circumferential direction, areas with different magnetization alternate in the axial direction; thus, a north pole is followed by a south pole. The magnitude of the magnetization is preferably sinusoidal or at least approximately sinusoidal.

[0040] A circuit board 5, comprising sensors, is provided on the housing part 1. Each track on the circuit board 5 is assigned a sensor for detecting the magnetic field. Hall sensors are preferably used as sensors. The signals from the sensors are fed to an analog-to-digital converter with a resolution of, for example, 10 bits or more.

[0041] The respective extent of the north and south pole regions, i.e., the period length of the essentially sinusoidal magnetization, in each track is different and is specifically selected such that the sensor signals can be uniquely assigned to each angular position of the fan wheel. In particular, the period lengths and the associated phase differences between the sinusoidal curves in the individual tracks are designed according to the de Nonius principle.

[0042] Preferably, three tracks are used, the number of north pole regions provided in the circumferential direction being 56 in the first track, 63 in the second track, and 64 in the third track. However, other number combinations selected according to the vernier principle can also be used advantageously. In particular, a number combination is advantageous in which (2^N) is selected in the first track, (2^N - 1) in the second track, and (2^N - 2^(N / 2)) in the third track, where N is an integer. Alternatively, an embodiment is also conceivable in which (9 * N) is selected in the first track, (-1 + 10 * N) in the second track, and (10 * N) is selected in the third track, where N is an integer.

[0043] In this way, the angular position can be clearly determined from the respective sensor signals after their analog-to-digital conversion during one revolution of the fan wheel.

[0044] In further embodiments according to the invention, an electromagnetically actuated brake is provided in the region of the housing part 1. This brake also includes a brake coil, so that a strong magnetic field can be generated, particularly in the axial direction, which can be at least partially shielded by the housing part 1.

[0045] In further embodiments according to the invention, the sensors operate differentially. For this purpose, at least two sensors are assigned to each track. These sensors are spaced apart from each other in the circumferential direction and each detect the magnetization of the same track. However, to determine the angle, only the difference between the two associated sensor signals is determined, so that a homogeneous component in the magnetic field—i.e., a magnetic field component that acts equally on both sensors assigned to the same track—is eliminated. The magnetic field of the brake or the stator, for example, is effective as such a magnetic field component and can be eliminated due to the differential detection.

[0046] By arranging a differential detection for each track on the circuit board 5, particularly low-noise information about the angle of the fan wheel 4 can be acquired.

[0047] Even in the case of thermally induced length changes, in particular changes in the distance between the circuit board 5 with sensors and the fan wheel 4, the differential detection reduces the temperature dependence of the detected angle information.

[0048] The pole disc 6 is preferably made of sintered ferrite material and is adhesively bonded to the fan wheel 4, which is made of aluminum.

[0049] In further embodiments according to the invention, the pole disk 6 is cast in a fan wheel 4 made of plastic, in particular an injection-molded fan wheel 4.

[0050] In further embodiments of the invention, differential detection can be achieved by arranging a larger number of sensors at appropriate spacing instead of two. This allows for even less interference.

[0051] In further embodiments of the invention, the analog-to-digital converter is designed with 12 bits or more.

[0052] In Fig. 2 shows a further embodiment of the invention. A Ferraris sensor is arranged at a smaller radial distance than the three tracks, the field winding 26 of which is arranged on a C-shaped core, on which a pickup winding 28 is also wound. Overall, this coil arrangement with the C-shaped core is screw-connected to the housing part 1. An eddy current ring 27 is connected in a rotationally fixed manner to the rotor shaft. Thus, by energizing the field winding and determining the voltage induced in the pickup winding 28 due to the eddy currents induced in the eddy current ring 27, a rotational acceleration can be determined. The electronic components required to carry out the determination are also arranged on the circuit board 5. Thus, all sensors can be arranged on the circuit board, as can the associated evaluation electronics components. This enables particularly simple production.Furthermore, the recorded values ​​can be converted into digital values, allowing a digital data stream to be transmitted from the circuit board to another electronic device, such as a converter or higher-level controller. Due to the digital transmission and the associated creation of a digital communication interface, a high data stream can be transmitted, which includes not only the angle values ​​recorded according to the vernier principle, but also the recorded angular acceleration values.

[0053] By supplying this data, a converter control unit with particularly good control characteristics can be realized. While the respective recorded angle values ​​can be used to determine the rotor shaft's rotational speed, which can be made available to the control unit as an actual value, this only yields a rotational acceleration with a high noise component, i.e., a low signal-to-noise ratio. To improve the control behavior, the recorded rotational acceleration value, which has an improved signal-to-noise ratio, is also fed to the control unit.

[0054] In Fig. 2, the Ferraris sensor (26, 27, 28) measuring the rotational acceleration is arranged at a smaller radial distance than the Hall sensors arranged opposite the tracks. This reduces the interference fields. Thus, disruptive influences are reduced.

[0055] In Fig. 5 is a revolution counter in addition to the design according to Fig. 1 is arranged integrated on the circuit board 5. The magnetically sensitive sensor is protected by a shield 11 from the magnetic fields generated by an electromagnetically actuated brake arranged on the side of the circuit board 5 facing away from the fan. Thus, the magnetic field of an additional permanent magnet 9 arranged on the fan can be detected with a very good signal-to-noise ratio.

[0056] An energy storage device, such as a battery 10, is connected to the circuit board and enables the rotations to be recorded even in the event of a power failure. Thus, Hall sensors or other sensors requiring power supply are necessary to detect the passing magnet 9.

[0057] As in Fig. 4, in contrast to the Fig. 3 Energy-generating sensors can be used as sensors when the permanent magnet 9 rotates past. In particular, pulse wires, i.e. Wiegand wires, or microgenerators can be used as sensors. The pulse wires and microgenerators suddenly trigger at a critical angular position of the permanent magnet 9 and generate enough energy to prevent electronic processing, in particular counting, from being enabled. FRAM technology is preferably used for the counting components. Before triggering, the pulse wire is slowly pre-tensioned at the atomic level depending on the rotational movement of the permanent magnet. The microgenerator also uses a slow pre-tensioning process and a REED contact to achieve a sudden trigger at the critical angular position, thus releasing enough energy to supply the counting components.

[0058] Advantageously, the sensors are arranged on circuit board 5. This allows the recorded and preprocessed values ​​to be digitally transmitted via a single data line. Additional mechanical connectors or cables are thus eliminated.

[0059] By integrating the sensors on the circuit board according to Fig. 1 to 4, the sensors are arranged in essentially the same axial space, thus achieving a particularly compact arrangement. In particular, the axial length is independent of the number of sensors, i.e., the sensor for the angular position of the rotor shaft, the sensor for the number of complete revolutions already completed after Fig. 3 or Fig. 4 and sensor for the rotational acceleration according to Fig. 2.

[0060] All associated recorded values, i.e., angle value, rotation speed, and / or angular acceleration value, can be transmitted to a converter and / or a controller via the same interface. The values ​​are recorded repeatedly in sequence, so that the value progression is recorded and transmitted essentially in real time.

[0061] According to the invention, a temperature sensor is mounted on the circuit board, the measured value of which is transmitted via galvanic isolation to the electronic circuitry located on the circuit board. This eliminates systematic temperature influences. The temperature value is also transmitted via the communication interface.

[0062] According to the invention, the motor temperature and / or the torque transmitted by the motor's rotor shaft are also recorded, and the recorded values ​​are transmitted via galvanic isolation to the electronic circuit located on the circuit board. The data is then transmitted via the communication interface.

Claims

[1] Arrangement for determining the angular position of a shaft, which is mounted in a housing part with at least one bearing, a fan wheel is connected to the shaft in a rotationally fixed manner, wherein a printed circuit board is attached to the housing part, in particular wherein the normal direction of the printed circuit board is aligned parallel to the shaft axis, in particular wherein the circuit board is arranged between a housing part and the fan wheel, where - magnetised areas, in particular a pole disc, are provided on the side of the fan wheel facing the circuit board, which can be detected by sensors arranged on the circuit board so that the angle value of the shaft can be recorded, - another permanent magnet is arranged on the fan wheel, to which a sensor for detecting the number of revolutions is assigned on the circuit board, characterized by , that a rotational acceleration sensor, in particular a Ferraris sensor, is connected to the circuit board, which comprises an electrically conductive ring which is connected to the fan wheel in a rotationally fixed manner, whereby the values ​​recorded by the sensors, i.e. respective angle values, rotational acceleration values ​​and revolution number values, are transmitted via the same digital communication interface to another electronic circuit, such as an inverter and / or higher-level control system, the sensors are connected to an electronic circuit which is connected to the communication interface, wherein at least parts of the communication interface, the sensors and the electronic circuit are arranged on the circuit board, wherein an evaluation electronics is arranged on the circuit board, to which the sensor signals are fed and the evaluation electronics is designed in such a way that - an angle value for the angular position of the fan wheel, - a rotational speed value of the fan wheel and - a rotational acceleration value of the fan wheel is determined, wherein the communication interface is connected to a control unit of a converter which feeds an electric motor, the rotor shaft of which is the shaft, in particular to which a detected motor current value is supplied and which provides a motor voltage, whereby the recorded angle values ​​and rotational acceleration values ​​are fed to the control unit, wherein a temperature sensor is additionally arranged on the circuit board, the recorded value of which is also transmitted via the communication interface, wherein the shaft is arranged in a motor and in the motor, in particular in the stator windings of the motor, a means for detecting the motor temperature and / or in the motor a means for detecting the torque transmitted by the shaft is arranged, wherein the recorded values ​​are transmitted to the electronic circuit arranged on the printed circuit board via a galvanic isolation, in particular wherein the recorded values ​​are also transmitted to the further electronic circuit via the same digital interface. [2] Arrangement according to claim 1, characterized by that an energy storage device is arranged on the printed circuit board to supply an electronic component in the event of a failure of the supply voltage assigned to the electronic circuit arranged on the printed circuit board. [3] Arrangement according to at least one of the preceding claims, characterized bythat the ring of the rotational acceleration sensor is firmly connected to the fan wheel. [4] Arrangement according to at least one of the preceding claims, characterized by that the communication interface has at least one interface and / or one connector part. [5] Arrangement according to at least one of the preceding claims, characterized by , that the magnetized areas form three concentric tracks and each track is assigned at least one sensor on the circuit board, wherein in each track in the circumferential direction the axially executed magnetization direction is executed alternately, in particular thus a north pole area magnetized in the axial direction is followed by a south pole area. [6] Arrangement according to at least one of the preceding claims, characterized bythat the cooling air flow generated by the fan wheel cools the housing part, in particular wherein the fan wheel is a radial fan wheel and the generated radial cooling air flow can be deflected in a substantially axial direction by a fan cover provided on the housing part. [7] Arrangement according to at least one of the preceding claims, characterized by that the tracks are applied and / or realized in a disc, in particular a pole disc, made of ferrite material. [8] Arrangement according to at least one of the preceding claims, characterized by that the period lengths of the respective magnetization curve provided within the respective track in the circumferential direction are assigned according to the vernier principle. [9] Arrangement according to at least one of the preceding claims, characterized by , that three tracks are planned, whereby the number of North Pole areas - in a first track 2^N, - in a second track 2^N - 1, - in a third track 2^N - 2^(N / 2) where N is an integer, and / or that three tracks are planned, whereby the number of North Pole areas - in a first track 10 * N, - in a second track 10 * N - 1, - in a third lane 9 * N amounts. [10] Arrangement according to at least one of the preceding claims, characterized by , that in each track the magnetization direction is axial and has a sinusoidal magnitude in the circumferential direction, and / or that at least two sensors are assigned to each track, in particular for differential detection of the magnetization curve in the circumferential direction, and / or that the housing part for a magnetic field generating device, such as the stator winding of an electric motor and / or brake coil winding of an electromagnetically actuated brake, is at least partially housing-forming, and / or that a means for shielding magnetic fields is provided between the housing part and the sensors, and / or that the sensors are magnetic field sensitive sensors, especially Hall sensors. [11] Electric motor with an arrangement according to at least one of the preceding claims, characterized by that the shaft is the rotor shaft of the electric motor and the fan wheel is arranged on the rotor shaft.

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