Electric motor and position holding device for such an electric motor
View Patent ↗An electric motor, particularly for an actuating device for displacing a control device, such as a valve, a gate valve, a blow-out preventer or the like, for use in oil or gas production includes a stator and a rotor assigned to a motor shaft, and a position holding device for exerting a holding torque on the motor shaft. To improve an electric motor of this type such that said motor is of a compact structure, includes less additional parts for a corresponding position holding device and, particularly in case of failure of an external power supply, reliably prevents a situation where the motor shaft is moved out of the attained position upon corresponding pressure application e.g. by the control device, the position holding device comprises a plurality of permanent magnets, the permanent magnets being arranged in radial direction relative to the rotor and the motor shaft, respectively.
1. An electric motor for an actuating device for displacing a control device, such as a valve, a gate valve, a blow-out preventer or the like, for use in oil or gas production, the electric motor comprising:
a stator and a rotor assigned to a motor shaft, and a position holding device for exerting a holding torque on the motor shaft;
wherein the position holding device comprises a plurality of permanent magnets and/or coils with or without a core material like iron, the permanent magnets and/or coils with or without a core material like iron being arranged in radial direction relative to the rotor and the motor shaft, respectively.
2. The electric motor according to claim 1 , further comprising at least a plurality of permanent magnets each in electromagnetic communication with an electrical compensation coil.
3. The electric motor according to claim 2 , wherein the electrical compensation coil is wound around the permanent magnet.
4. The electric motor according to claim 2 , wherein the compensation coil is connected to a control device for controlling the magnetic field thereof.
5. The electric motor according to claim 2 , wherein the stator comprises pole shoes and the permanent magnets are arranged in circumferential direction of the stator between the pole shoes.
6. The electric motor according to claim 1 , further comprising a plurality of permanent magnets linearly arranged in longitudinal direction of the rotor and the motor shaft, respectively.
7. The electric motor according to claim 1 , further comprising permanent magnets arranged distributed in circumferential direction of the stator and equally spaced apart.
8. The electric motor according to claim 1 , further comprising permanent magnets arranged at one or both ends of the rotor and the stator.
9. The electric motor according to claim 1 , further comprising permanent magnets arranged in pairs opposite each other relative to the rotor.
10. The electric motor according to claim 1 , further comprising a rotor or armature extension projecting laterally from the stator and permanent magnets in magnetic communication with the rotor or armature extension.
11. The electric motor according to claim 10 , further comprising a stator extension flanged onto the stator and substantially sleeve-shaped, the permanent magnets being arranged on the inside of the stator extension.
12. The electric motor according to claim 2 , wherein the permanent magnets are made from materials based on rare earths, optionally with additions, such as iron, cobalt, boron, or the like.
13. A position holding device for an electric motor of an actuating device for displacing a control device, such as a valve, a gate valve, a blow-out preventer, or the like, for use in oil or gas production, wherein the electric motor comprises a stator and a rotor for rotating a motor shaft, the position holding device being capable of exerting a holding torque on the motor shaft and comprising a plurality of permanent magnets for exerting a corresponding holding force on the rotor or motor shaft, the permanent magnets being arranged in radial direction relative to the rotor.
14. The position holding device according to claim 13 , the position holding device being configured as a retrofit kit.