Magnetic brake for window covering powered by DC motor
View Patent ↗A braking magnet is attached to the housing of a motor of a motorized component such as a window covering. With this structure the motor is braked from turning under the weight of the window covering when deenergized.
1. A powered assembly, comprising:
at least one object that can be moved between a first configuration and a second configuration;
at least one DC motor including a stator and a rotor separated by an air-gap, the stator comprising a housing and two stator magnets producing in the air-gap a main magnetic field in a first direction and the rotor rotating about a rotor axis;
at least one actuator coupled to the rotor of the motor and the object to move the object when the motor is energized; and
at least one additional magnet disposed on the housing and externally to the housing in such a way that the at least one additional magnet and the rotor are magnetically coupled, the at least one additional magnet producing in the air-gap an auxiliary magnetic field in a second direction substantially perpendicular to the first direction.
2. The powered assembly of claim 1 , wherein the second direction is substantially perpendicular to the rotor axis.
3. The powered assembly of claim 1 , wherein the motor is powered by at least one dc battery.
4. The powered assembly of claim 1 , wherein the at least one magnet is disposed in a recess formed in the housing.
5. The powered assembly of claim 1 , comprising one additional magnet and a magnetic field closing concentrator, the additional magnet being sandwiched between the magnetic field closing concentrator and the housing and the magnetic field closing concentrator being oriented in such a way that the auxiliary magnetic field has in the air-gap two radial components that are anti-parallel.
6. The powered assembly of claim 1 , wherein the object is selected from the group consisting of window coverings, awnings, skylight coverings, curtains, and screens.
7. A method for operating an object that can be moved between a first configuration and a second configuration, the method comprising:
providing a DC motor including a stator and a rotor separated by an air-gap, the stator comprising a housing and two stator magnets producing in the air-gap a main magnetic field in a first direction and the rotor rotating about a rotor axis;
coupling the rotor to the object such that the object is moved when the motor is energized;
disposing the at least one additional magnet on the housing and externally to the housing in such a way that the at least one additional magnet and the rotor are magnetically coupled, and;
orienting the at least one additional magnet such that it produces in the air-gap an auxiliary magnetic field in a second direction substantially perpendicular to the first direction.
8. The method of claim 7 , comprising:
forming at least one recess in the housing of the motor, and
disposing the at least one magnet in the at least one recess.
9. The method of claim 7 , comprising:
disposing a magnetic field closing concentrator on one magnet, the magnetic field closing concentrator being oriented in such a way that the auxiliary magnetic field has in the air-gap two radial components that are anti-parallel.
10. The method of claim 7 , wherein the object is selected from the group consisting of window coverings, awnings, skylight coverings, curtains, and screens.