Support structure for drive source

A support structure for an electric motor (72) used for a blower (7) of an air-conditioning system of a vehicle, wherein the motor is supported and fixed on a scroll casing (74) through a support member (73), the scroll casing (74) being provided on an air-conditioning system casing (2) forming an air path, and wherein the blower is arranged in an upstream portion of the air-conditioning system casing (2), the blower blowing the introduced air into the vehicle through a plurality of air outlets, the support structure comprising:

• a centrifugal multiblade fan (71) having a multiplicity of blades around a rotary shaft for blowing air by the centrifugal force;
• the electric motor for rotationally driving the fan;
• the scroll casing, which encases the fan therein and collects the air blown out from the fan to increase the pressure of the air;
• the support member (73) being made of resin through which the motor is supported and fixed on the scroll casing (74), wherein the support member comprises:
• a motor casing (73a), which encases the motor;
• a flange (73b) extending radially outward over the entire periphery of the motor casing, the flange and the motor casing being continuously and integrally formed of resin;
• a plurality of fastening members for fastening the radially outer side of the flange to the scroll casing;
• a low-stiffness portion (73d) arranged in the portion nearer to the center of the flange and formed in a ring form around the motor casing, the low-stiffness portion having a smaller thickness than the outer peripheral side portion of the flange nearer to the scroll casing, when the thicknesses are measured in a direction perpendicular to the radial direction, so that the stiffness of the motor side portion of the flange is smaller than the stiffness of the outer peripheral side portion of the flange;
• a high-stiffness portion (73e) arranged at the peripherally outside portion of the low-stiffness portion in the flange, the thickness of the high-stiffness portion being larger than the thickness of the low-stiffness portion to make the high-stiffness portion more difficult to vibrate than the low-stiffness portion so that the vibration rate of the high-stiffness portion is lower than the vibration rate of the low-stiffness portion when the motor vibrates.