Water pump and method for producing water pump
A pump is provided which includes a pump housing, a drive shaft rotatably installed in the pump housing through a ball bearing, a pulley integrally connected to one end of the drive shaft through a flange wall, an impeller connected to the other end of the drive shaft, a cylindrical base part integrally connected to an outer periphery of the flange wall and six through openings formed in an outer peripheral part of the flange wall, in which each of the through openings has, at a generally middle part of a bottom surface of an inner surface thereof, a pathway groove that extends substantially along an inner cylindrical surface of the cylindrical base part, so that the performance of discharging water, dust and the like from the through openings formed in the flange wall is increased.
1. A water pump comprising:
a pump housing having a cylindrical portion at an axial end;
a drive shaft rotatably supported in the pump housing;
a pulley including a discal end wall that is connected to an end portion of the drive shaft and a cylindrical base part that is integrally connected to an outer periphery of the discal end wall and shaped to surround the cylindrical portion;
a bearing that is interposed between the cylindrical base part and the cylindrical portion to rotatably bear the drive shaft; and
an impeller that is connected to the other end of the drive shaft to rotate integrally, wherein
the discal end wall is formed with a plurality of through openings that communicate an inside with an outside of the discal end wall,
relative to a rotational axis of the water pump, each of the through openings defines, at a location on each through opening that is most radially distant from the rotational axis of the water pump, a pathway groove that extends substantially along an inner cylindrical surface of the cylindrical base part,
an opening area of the pathway groove is smaller than that of the corresponding through opening,
a width of the pathway groove is reduced as the pathway groove extends radially outward, and
the pathway groove extends through the discal endwall along a direction that is parallel to a longitudinal axis of the drive shaft.
2. A water pump as claimed in claim 1 , wherein a width of the through opening is increased as the through opening extends radially outward.
3. A water pump as claimed in claim 2 , wherein a cross-section of the through opening has a triangular shape.
4. A water pump as claimed in claim 1 , wherein the through openings of the discal end wall are arranged in a circumferential direction at evenly spaced intervals.
5. A water pump as claimed in claim 1 , wherein each of the through openings is circular.
6. A water pump as claimed in claim 1 , wherein each of the through openings is elliptical.
7. A water pump as claimed in claim 1 , wherein each of the through openings is rectangular.
8. A water pump as claimed in claim 1 , wherein the pathway groove is arcuate in a transverse cross section.
9. A water pump as claimed in claim 8 , wherein the pathway groove is one of a plurality of pathway grooves respectively provided by the through openings.
10. A water pump as claimed in claim 1 , wherein the bearing is a ball bearing including an inner race fixed to the cylindrical portion, an outer race fixed to the cylindrical base part and balls operatively disposed between the inner and outer races.