Water pump and method for manufacturing water pump

A water pump comprising:

• a pump housing having, at an axial direction one end side thereof, a cylindrical portion;
• a drive shaft rotatably supported in the pump housing, the drive shaft being formed with synthetic resin material containing reinforcing fiber material;
• a pulley having a disk-shaped end wall fixed to one end portion of the drive shaft and a cylindrical base portion connected to an outer peripheral edge of the end wall so as to encircle the cylindrical portion, the pulley being formed integrally with the drive shaft with the synthetic resin material containing the reinforcing fiber material;
• a cylindrical metal member fixed to an inner periphery of the cylindrical base portion;
• a bearing unit interposed between the metal member and the cylindrical portion and rotatably supporting the drive shaft;
• an impeller secured to the other end portion of the drive shaft so as to be able to rotate integrally with the drive shaft, the impeller being formed with synthetic resin material containing fiber material;
• and
• a fixing member fixing the impeller to the drive shaft from the other end side of the drive shaft, and wherein
• the end wall of the pulley has a plurality of penetration holes that connect inner and outer sides of the end wall, and the reinforcing fiber material existing around the penetration hole has random orientation.

A method for manufacturing a water pump, the water pump having a pump housing having therein a pump chamber;

• a drive shaft rotatably supported in the pump housing;
• a pulley having a disk-shaped flange wall fixed to one end portion of the drive shaft, the pulley being formed integrally with the drive shaft with synthetic resin material containing reinforcing fiber material;
• and an impeller secured to the other end portion of the drive shaft so as to be able to rotate integrally with the drive shaft, the impeller being accommodated in the pump chamber, and the flange wall of the pulley being provided with a plurality of penetration holes that penetrate the flange wall and connect inner and outer sides of the flange wall, the method comprising:
• a first process of filling a mold for the pulley with molten synthetic resin material;
• and
• a second process of pressing the synthetic resin material by a boring jig and forming the plurality of penetration holes by a time when the synthetic resin material hardens after completion of the filling of the synthetic resin material.