Device for driving a winding shaft

Abstract

Device for driving a winding shaft for a rollable and unrollable curtain, such as roller shutters, roller doors, screens, awnings and blinds, with a motor (10) consisting of a stator (18) and rotor (16), a gearbox (11) for transmitting the movement of the motor (10) to the curtain and a brake, characterized in that the motor (10) is designed as a permanent magnet synchronous motor (PMSM), in which the rotor (16) has at least one multi-pole permanent magnet (PM) and the stator winding (STW) is multi-phase, wherein the rotor (16) moves at exactly the speed of the external magnetic field generated by the stator winding (STW).

Description

[0001] The invention relates to a device for driving a winding shaft for a rollable and unrollable curtain, such as roller shutters, roller doors, screens, awnings and blinds, with a motor consisting of a stator and rotor, a gearbox for transmitting the movement of the motor to the curtain and a brake.

[0002] Such a drive device with an asynchronous motor is already known in principle from EP 0 822 316 15 B1 of the applicant.

[0003] The patent describes a device for driving the winding shaft with a two-phase asynchronous motor. The braking device required for this application is typically mounted on the motor's rotor and actuated by the rotor's magnetic field. It can be a conical brake or a disc brake with one or more brake discs. The motor speed is reduced to the speed required for actuating the winding shaft by using a multi-stage reduction gear. The travel distance for switching off the drive at the curtain's end positions is detected by a sensor system on the motor's rotor shaft, consisting of an encoder system and a corresponding sensor. This sensor system can be designed as described by the applicant in EP 0 822 314 A3, either as an optical sensor system or, as is often the case, as a magnetic sensor system.

[0004] When operating a two-phase asynchronous motor, one phase of the winding is connected to the AC mains supply, while the second phase of the motor, in series with a substantial operating capacitor, is also connected to the same AC mains supply. This creates a rotating magnetic field inside the stator, which rotates precisely at the frequency of the applied AC voltage. This rotating magnetic field induces voltages in the conductor loops of the rotor, resulting in currents. These currents, in turn, generate magnetic fields that align with the rotating field of the stator, causing the rotor to rotate. Since a change in magnetic flux is necessary to induce the voltages in the conductor loops of the rotor, the rotor rotates more slowly than the stator field, i.e., asynchronously.The greater the torque demanded from the motor, the more the rotational speed of the rotor drops.

[0005] To manufacture such asynchronous motors, the laminations for the stator with the corresponding slots and the laminations for the rotor, also with corresponding slots, are first stamped from suitable transformer steel. Depending on the required power of the motor, these laminations are stacked into laminated cores of varying lengths for both the stator and the rotor and then firmly bonded together.

[0006] To complete the stator, insulation is first inserted into the slots. The necessary winding, consisting of enamel-insulated copper wire, is wound or prepared outside the stator and then mechanically drawn into the stator slots in a single operation.

[0007] The slots in the rotor laminations are filled with highly conductive metal and electrically connected at the ends, also with highly conductive metal, thus creating a squirrel-cage rotor with conductor loops. After mechanical finishing, the rotor lamination stack is slid onto a motor shaft and secured.

[0008] Manufacturing these types of drives therefore requires a large number of complex work steps. To produce such motors cost-effectively and in large quantities, manufacturers use many specialized and expensive tools and automated machines.

[0009] A disadvantage of the drive design described above is that such drives have poor efficiency and convert a large proportion of the supplied energy into unwanted heat. This heating must be limited to the permissible level for the winding by additional thermally actuated switches. Due to the rapid heating, the possible operating time of such a device is limited to a few minutes.

[0010] As also described in EP 2 821 583 B1, variable speed control of an asynchronous machine is very complex, since the frequency of the supply voltage must be influenced in such a way that the speed changed by the different load of the motor must also be compensated accordingly.

[0011] To overcome this problem of speed control of the asynchronous motor, it is also known to equip devices for moving winding shafts for this application with DC motors with brushes and commutators.

[0012] A typical brushed DC motor often uses permanent magnets attached to the motor housing and a rotor consisting of laminations with multiple coils. The winding ends of the coils are connected to ring-shaped insulated laminations called the commutator. The brushes in contact with these laminations always connect the winding corresponding to the applied voltage, resulting in a repulsion between the magnetic field generated by the rotor and the magnetic field of the permanent magnet in the housing.

[0013] This causes the rotor to turn. The switching of the voltage to the next winding of the rotor is called commutation and, in the motor just described, occurs mechanically. The switching point is directly dependent on the rotational position of the rotor. DC motors of this type are subject to wear on the brushes and the mechanical commutator. These motors require either a DC mains supply or a bulky power supply unit, as well as a separate electronic module for speed control.

[0014] Alternatively, EP 2 821 583 B1 describes the use of a brushless DC drive with electronic commutation to solve the problem. Motors with electronic commutation do not have the disadvantage of wear on the commutator and brushes. In these motors, the stator typically contains a multiphase winding, and the rotor carries permanent magnets. The magnetic field of the permanent magnets is not fixed relative to the motor housing but rotates. To operate this motor, an external electronic control is required. The rotor position serves as input information for the electronic control, and depending on the rotor position, the adjacent winding is energized, causing the rotor to continue rotating. Commutation does not occur mechanically but electronically within the electronic control, depending on the rotor position.This design requires the precise detection of the rotor position by several sensors integrated into the motor, along with a complex electronic control system that handles electronic commutation and speed control.

[0015] Both types of DC drives described above have different sheet metal shapes and manufacturing processes used in the motor compared to the previously used asynchronous motors and cannot be manufactured using the manufacturing technology used for asynchronous motors.

[0016] Based on EP 2 821 583 B1, the object of the invention is therefore to create a simple and cost-effective device for driving a winding shaft for a rollable and unrollable curtain, such as roller shutters, roller doors, screens, awnings and blinds, which eliminates as many of the aforementioned disadvantages of previous asynchronous motors as possible, but can be manufactured with the tools and automatic machines used to produce these previous asynchronous motor solutions and can also be varied in speed.

[0017] The solution to the problem results from the following features of claim 1: Device for driving a winding shaft for a rollable and unwindable curtain, such as roller shutters, roller doors, screens, awnings and blinds, with a motor consisting of a stator and rotor, a gearbox for transmitting the movement of the motor to the curtain and a brake, characterized in that the motor is designed as a synchronous motor with permanent excitation, in which the rotor has at least one multi-pole permanent magnet and the stator winding is multi-phase, wherein the rotor moves at exactly the speed of the external magnetic field generated by the stator winding.

[0018] The solution according to the invention has the fundamental advantage that it is a simple and cost-effective device, manufactured using previously used tools and automatic machines for the production of asynchronous motors according to the prior art, and which is also speed-controlled.

[0019] According to the invention, a rotor with at least one multipole permanent magnet is used as the rotor in a conventional stator of an asynchronous machine, resulting in a permanent magnet synchronous motor (PMSM). The rotor rotates at exactly the same speed as the external magnetic field generated by the stator winding. When the motor is under load, the rotor lags behind by the so-called rotor angle at the same speed of the stator's magnetic field. The rotor angle, typical for synchronous machines, is thus formed between the magnetic fields of the stator and the rotor. The rotor angle is proportional to the torque demanded by the motor. If the motor load becomes too high, the motor loses synchronization and stalls.

[0020] If the stator core is wound with three phases, as in a three-phase motor, three sinusoidal voltages shifted by 120° can be applied to this winding. These types of motors only require a three-phase sinusoidal power supply to operate.

[0021] The advantages of the PMSM solution compared to an asynchronous motor are its smaller size and smoother operation. A disadvantage of using a synchronous motor is that it won't start when directly connected to a standard mains supply; it only begins to rotate once the rotor reaches the speed of the stator field and is running synchronously. Since speed control is also required in our application, it makes sense to operate this PMSM with electronics capable of generating a three-phase AC network with variable frequency and voltage. This also provides a solution for starting the motor.

[0022] To achieve the necessary motor shutdown at the blind's end positions for this application, a magnet wheel is mounted on the rotor as an encoder, and Hall effect sensors are installed as a fixed position sensor, similar to conventional standard drives. These components serve as position sensors for the blind, as before. If the angle between the external encoder magnet wheel and the rotor magnet is also known, the pole angle of the synchronous motor can be determined, providing a value for the torque demanded from the motor, which can be used to control the device's end positions. Alternatively, the rotor magnet mounted on the rotor can also be used as a position encoder instead of the separate encoder magnet wheel.

[0023] One embodiment of the device according to the invention for driving a winding shaft is characterized in that the multi-pole permanent magnet contains several pole pairs.

[0024] Multipole permanent magnets with multiple pole pairs can concentrate the magnetic force over a larger area or on specific regions. This can lead to more efficient use of the magnetic field, as multiple poles allow for a more even distribution of the magnetic flux. Multipole permanent magnets with multiple pole pairs also help to reduce noise and vibration in machinery. Magnets always have multiples of two poles; therefore, they are often referred to as pole pairs.

[0025] In another embodiment, it is also possible that the stator lamination stack is designed as a stator lamination stack that is also common for asynchronous motors.

[0026] This has the advantage that the tools and automatic machines previously used in the manufacture of asynchronous motors can also be used for the device according to the invention.

[0027] Furthermore, it is possible that the device according to the invention contains a stator which is provided with a three-phase stator winding.

[0028] In a three-phase stator winding, each phase generates a magnetic field that is 120 degrees out of phase. This results in a smooth, continuous torque, which reduces vibrations and makes operation quieter. For example, a two-phase stator winding in a PMSM drive would function, but would run very roughly. Even if one phase fails in a three-phase stator winding (e.g., due to a line break), the system can continue to operate in a limited mode. In contrast, the failure of one phase in a two-phase system would lead to a complete standstill. Three-phase systems are widely used in industry and can be easily adapted for various applications. This also applies to the necessary semiconductors.

[0029] Another embodiment of the invention is characterized in that the necessary brake unit is arranged in the reduction gear, and in this context it is also possible that the brake is designed as a spring loop brake.

[0030] Advantageously, in a further embodiment, it is possible to arrange a sensor unit on the rotor, which can be used for end position control of the blind.

[0031] In this context, in one embodiment of the invention, it is also possible that the sensor unit arranged on the rotor is also used to determine the pole wheel angle of the synchronous machine and thus the load on the curtain.

[0032] Ultimately, one embodiment of the invention is characterized in that a control electronics provides a supply voltage of variable frequency and voltage.

[0033] This advantageously enables the control electronics to regulate the speed of the embodiment of the invention via the frequency, as well as to adjust the necessary torque within the application via the control voltage in order to maintain a constant speed. The control voltage can also be used to influence the motor's power consumption, which reduces heat generation. The control voltage makes it possible to keep the motor operating within its optimal range at all times.

[0034] In summary, the variable control voltage and variable frequency of a PMSM drive enables flexible, precise and efficient control, resulting in a multitude of advantages in roller shutter applications.

[0035] Further advantages of the invention will become apparent from the following description of an exemplary embodiment. The illustrations show: Fig. 1: a motor for driving a winding shaft, Fig. 2: the engine according to Fig. 1 in exploded view, Fig. 3: Front view of the engine according to the Fig. 1 and Fig. 2, Fig. 4: Sectional view according to section lines IV - IV in Fig. 3 and Fig. 5: a diagram of the stator winding of the motor according to the invention.

[0036] In the drawings, a motor for driving a winding shaft (not shown) is designated by the reference numeral 10.

[0037] The engine 10 is in the Fig. Figures 1 to 4 are shown. According to the exploded view in Fig. 2 the motor 10 is formed from left to right from a drive pinion A, which is connected to a gearbox 11 with spring brake 12, a drive pinion 13, a bearing shield with bearing 14, a winding head cap 15, a rotor 16 with rotor shaft 17, a stator 18 with a winding head, a winding head cap 19 with bearing, a magnet wheel 20, a contact shield 21 and a contact carrier 22.

[0038] The essential feature of the motor 10 according to the invention is that the rotor 16 has at least one permanent magnet (PM) and that the stator is provided with a multi-phase stator winding, wherein in the operating state the rotor 16 moves at exactly the speed of the external magnetic field generated by the stator winding STW.

[0039] In the Fig.Figure 5 shows the schematic of the stator winding STW within the context of a development of the stator 18 (dashed, rectangular area). The designations 1 to 12 indicate slots 23, in which, in the three-phase version of the stator winding STW, three differently marked enamel-insulated copper wires 24, 25 and 26 are inserted, which are connected to the terminals U1, U2 and W1, W2 as well as V1, V2.

[0040] In operating mode, the rotor 16 rotates exactly at the speed of the external magnetic field of the stator winding STW. When the motor 10 is under load, it lags behind the stator winding STW by the so-called load angle at the same speed. If the load on the motor 10 becomes too great, the motor 10 loses momentum and stalls. If the stator winding STW is wound three-phase, as in a three-phase motor, three sinusoidal voltages shifted by 120° can be applied to this winding. These types of motors 10 therefore require a three-phase, sinusoidal power supply, in which case no electronic commutation takes place. Reference symbol list 10 Motor 11 gearboxes 12 spring brake 13 drive pinions 14 warehouses 15 winding head cap 16 Rotor 17 Rotor shaft 18 Stator with winding head 19 Winding head cap 19 with bearing 20 magnetic wheel 21 Contact plate 22 contact carriers 23 slots of the stator 24, 25, 26 enamelled copper wires A drive pinion PM permanent magnet STW Stator winding U1, U2, W1, W2, V1, V2 Connections of the three-phase motor QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] EP 0 822 316 15 B1

[0002] EP 0 822 314 A3

[0003] EP 2 821 583 B1 [0010, 0014, 0016]

Claims

[1] Device for driving a winding shaft for a roll-up and roll-down curtain, such as roller shutters, roller doors, screens, awnings and blinds, comprising a motor (10) consisting of a stator (18) and rotor (16), a gearbox (11) for transmitting the movement of the motor (10) to the curtain and a brake, characterized by , that the motor (10) is designed as a permanent magnet synchronous motor (PMSM) in which the rotor (16) has at least one multi-pole permanent magnet (PM) and the stator winding (STW) is multi-phase, wherein the rotor (16) moves at exactly the speed of the external magnetic field generated by the stator winding (STW). [2] Device according to claim 1, characterized by , that the multipole permanent magnet (PM) contains multiple pole pairs. [3] Device according to claim 1 or 2, characterized by , that the stator lamination stack is designed as a stator lamination stack that is also common for asynchronous motors. [4] Device according to one of the preceding claims, characterized by , that the stator (18) contains a three-phase stator winding (STW). [5] Device according to claim 1 or any of the following claims, characterized by , that the necessary brake unit (12) is arranged in the reduction gearbox (11). [6] Device according to claim 5, characterized by that the brake is designed as a spring-loaded loop brake. [7] Device according to one of the preceding claims, characterized by , that a sensor unit is arranged on the rotor (16) which is used for end position control of the blind. [8] Device according to claim 7, characterized by , that the sensor unit arranged on the rotor (16) is also used to determine the pole angle of the synchronous machine and thus the load caused by the curtain. [9] Device according to any one of the preceding claims, characterized bythat a control electronics system provides a supply voltage of variable frequency and voltage.

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