Supporting structure for a rotor

A combination of a rotor and a supporting structure for the rotor, the combination comprising:

• a base provided with a metal axle tube;
• a holding member securely mounted in the metal axle tube, the holding member including a hole and an inner flange formed on an inner periphery defining the hole, said inner flange having an axial thickness that is thin relative to an axial length of the holding member to minimize contact between said inner flange and a shaft extending through said hole;
• a supporting member securely mounted in the metal axle tube and including as supporting portion;
• a fixing member securely mounted in the metal axle tube and including an opening;
• a rotor having a permanent magnet, the shaft being provided at a center of the rotor and including an engaging groove, the shaft being extended through the opening of the fixing member with an end face of a distal end of the shaft rotatably resting on the supporting portion of the support member and with the fixing member engaging with the engaging groove of the shaft, whereby the shaft and the thin inner flange of the holding member have a slight contact therebetween;
• and
• a balance plate mounted to the base and made from magnetically conductive material, the balance plate and the permanent magnet attracting each other to thereby provide an auxiliary balance force for rotation of the shaft on the thin inner flange of the holding member.