DE7344638U - Starting aid for synchronous motors with permanent magnet rotors - Google Patents

Description

MAN - watch and electrical apparatus fiibri! '! - Dcmauaschirippn; ',,' Leaf ,

To the German Patent Office, Munich St, / Bl. U-

December 10, 1973

MAX STEG

to write:

Starting aid for synchronous motors with permanent magnet rotors.

Synchronous motors with permanent magnet rotors are very easy to use Construction and therefore cheap to manufacture. You can with relatively good efficiency for low speeds (200 rpm to 750 rpm) can be built and achieved as they have no wearing parts such as collector, slip rings and Brushes have a long service life with little effort. As with all synchronous motors, it goes without saying in these, the speed is independent of voltage and load fluctuations.

Due to the design, however, they cannot run up asynchronously but must accelerate to the nominal speed within an electrical half-wave (0.01 "at 50 Hz). The motor must not only overcome the static load torque, but also an acceleration torque of the size M = during start-up. If) -rr. The angular acceleration - ^ r is also given for a given nominal speed and mains frequency, so that the acceleration torque is directly proportional to the load's moment of inertia H. If this is too great, the motor cannot start, so that it can In the cases that frequently occur in practice, it could not be used. If constant speeds are required, one must switch to much larger and more expensive hysteresis synchronous motors a gear, or at least one gear stage more is required To facilitate the start-up of synchronous motors with permanent magnet rotors, it has already been proposed to arrange thin spokes made of resilient material between the shaft of the motor and a rotor ring. - In this way it is possible to make starting easier and to avoid vibrations, but at the expense of considerable effort (DGM 1 909 684).

MAX STEGMANN - Clock and Electrical Apparatus - Donau ^ chiOqen Blatt

to be attributed to: To the German Patent Office, Munich St./Bl.

December 10, 1973

The object of the present invention is to achieve this advantage of facilitated and vibration-free start-up with the simplest possible, to achieve reliable means and cheap to manufacture.

According to the invention, a synchronous motor with a permanent magnet rotor can be brought to a start even with a high moment of inertia of the load if there is a slip clutch between the axis and the load switches whose transmittable torque is greater than the static load torque and less than the starting torque of the motor. The motor can now start immediately. The torque by which the slip torque of the clutch is greater than the static load torque, now accelerates the load from speed 0 to the nominal speed.

The drawings show two exemplary embodiments of the invention Start-up help. Fig. 1 shows a structurally very simple one and inexpensive arrangement. The magnetic ring 1 of the rotor is not rigidly connected to the axis 2, but can be rotated her stored. By a spring 3 it is pressed against a disc 4 fixedly connected to the axle, so that it is through the here occurring friction takes axis 2 with it. On the one hand, the spring 3 rests against one that is firmly connected to the axle 2 Ring 5 and on the other hand to an end face of the inner ring 6. Exceeds the sum of the static load and acceleration torque the friction torque of this clutch, which is given by the coefficient of friction, spring force and diameter of the friction surface, so the rotor can turn without the axis. However, the frictional torque applied by the clutch always acts on them. The rotor can therefore start up instantly with the synchronous speed and the moment of inertia driven by the axis Accelerate more or less quickly depending on its size.

MAX STEGMANN - Clock and Electrical Apparatus Factory - Donaueschlftgpn 'Sheet ^J / |

to be attributed to: ^{To the German} Patent Office, Munich St. / Bl. iy%

December 10, 1973

Fig. 2 shows a further simplified embodiment. Here, the magnetic field of the magnetic ring 1 causes the one Inner ring 6 made of non-magnetic material (preferably plastic) has that steel ring 8, which is fixed to axis 2 is connected, is pulled against the magnetic ring 1 via the air gap 7. To increase the frictional torque in the relatively With low magnetic axial forces, the friction surface 9 can expediently be designed to be conical. At the same time, this results in good centering of the inner ring 6 and as far as possible avoidance of vibrations. In addition, a relatively large tolerance between the inner ring 6 and the axis 2 is made possible with respect to the axis 2.

Claims (4)

MAX STEGMANN · Uhr- und ElektroapparatembrlH - Oonauaschtagen Blatt "n the German Patent Office, Munich St./Bl. 10.12. To write: Protection claims 1) Starting aid for synchronous motors with permanent magnet rotors, characterized in that the magnetic ring (1) of the rotor is rotatably mounted on the axis (2) and with it this is connected via a slip clutch./ 2) start-up aid according to claim 1, characterized in that the magnetic ring (1) rests with the end face of its inner ring (6) under the pressure of a spring (3) against a disk (4) firmly connected to the shaft (2). / 3) start-up aid according to claim 1, characterized in that that the magnetic ring (1) sitting on an inner ring (6) made of non-magnetic material and the shaft (2) is connected via a steel ring (8) which has an air gap (7) opposite the magnetic ring (1) and is pressed against the rotor (1,6) in the axial direction by magnetic forces. 4) start-up aid according to claim 3, characterized in that the steel ring (8) with a conical friction surface (9) engages in a conical recess of the inner ring (6).