Motor
A BLDC motor for driving a cross flow fan in an air-conditioning application has an external rotor and an internal stator. The stator is a salient pole stator with insulated pole teeth and conductor coils. The inner diameter of the stator supports a single bearing. An electronic PCBA for control of the BLDC motor is optionally attached to the stator, all of which is encapsulated in a thermoset resin. The rotor comprises permanent magnet component(s) and a rotor frame. The rotor frame includes a stub axle that engages with the bearing element and features to provide torsional or rotational compliance between the rotor magnets and the fan. A level of compliance is provided between the bearing element and the stator to allow for angular misalignment between the rotational axis of the fan and the stator.
1. A motor comprising:
a stator comprising an annular core having an axis, stator poles extending radially from the annular core, and phase windings wound on the stator poles; and
a rotor comprising:
rotor poles facing ends of the stator poles,
a rotor axle extending axially from the rotor to an inside of the annular core, and
only one bearing element, the bearing element mounted inside the annular core and being positioned between the rotor axle and the stator to rotationally couple the rotor to the stator wherein allowance for misalignment between the stator axis and the rotor axle is provided by at least one of (a) the bearing element comprising a spherical bearing and (b) a compliant mount for the bearing element being positioned radially between the rotor and the stator;
the stator further comprising:
a bearing locating member that mounts the bearing element radially inside the annular core, and
an insulator covering surfaces of the stator poles, the windings wound onto the stator poles over the insulator, and the bearing locating member being integrally formed with the insulator.
2. The motor as claimed in claim 1 , wherein the motor comprises the compliant mount and the compliant mount is an elastomeric sleeve or rubber sleeve providing a resilient mount for the bearing element, positioned between the bearing element and the bearing locating member or between the bearing element and the rotor axle.
3. The motor as claimed in claim 1 , wherein the bearing element is axially located at or near to a magnetic centre plane of the motor.
4. The motor as claimed in claim 3 , wherein the distance between an axial centre of the bearing element and the magnetic centre plane of the motor is less than about 20% of the axial length of the annular core.
5. The motor as claimed in claim 1 , wherein the spherical bearing is a ball joint comprising a ball component received in a socket.
6. The motor as claimed in claim 1 , wherein the bearing locating member comprises a radially inward facing surface or surfaces and an axial facing surface for mounting the bearing element radially and axially.
7. The motor as claimed in claim 6 , further comprising an encapsulant encapsulating the annular core, the phase windings, and the bearing locating member, the encapsulant rigidly supporting the bearing locating member.