Water pump and assembly method for water pump

Abstract

Water pump has a drive shaft inside pump housing, a pulley provided at one end of drive shaft, and impeller fitted onto other end portion of drive shaft through fitting hole. Restraining part restraining maximum fitting position of impeller in axial direction is provided between other end portion of drive shaft and fitting hole of the impeller, fixing member restraining axial direction movement of impeller positioned in the maximum fitting position in cooperation with restraining part is provided at tip end side of other end portion of the drive shaft, and the cross-sectional shape of fitting part, which is fitted into fitting hole of the impeller, of other end portion of drive shaft is formed as a rotation restraining part, and cross-sectional shape of fitting hole of impeller is formed into same cross-sectional shape as fitting part of other end portion of drive shaft, as rotation restraining part.

1 . A water pump comprising:
 a drive shaft inserted and located in an inside of a pump housing and formed with synthetic resin material;   a pulley provided at one end portion of the drive shaft and rotating integrally with the drive shaft, the pulley being configured to rotate by transmission of power from a drive source; and   an impeller formed with synthetic resin material, having a fitting hole and fitted onto the other end portion of the drive shaft through the fitting hole, and wherein   the drive shaft and the impeller are configured so that
 a restraining part that restrains a maximum fitting position of the impeller in an axial direction is provided between the other end portion of the drive shaft and the fitting hole of the impeller, 
 a fixing member that restrains an axial direction movement of the impeller positioned in the maximum fitting position in cooperation with the restraining part is provided at a tip end side of the other end portion of the drive shaft, and 
 a cross-sectional shape of a fitting part, which is fitted into the fitting hole of the impeller, of the other end portion of the drive shaft is formed as a rotation restraining part, and a cross-sectional shape of the fitting hole of the impeller is formed into the same cross-sectional shape as the fitting part of the other end portion of the drive shaft, as the rotation restraining part. 
   
     
     
         2 . The water pump as claimed in  claim 1 , wherein:
 the cross-sectional shape of the fitting part of the other end portion of the drive shaft is formed into a shape having no corner, and the cross-sectional shape of the fitting hole of the impeller is formed into a shape having no corner which is the same shape as the fitting part of the other end portion of the drive shaft.   
     
     
         3 . The water pump as claimed in  claim 2 , wherein:
 the whole cross-sectional shape of the fitting part of the other end portion of the drive shaft is formed into a curved surface shape, and the whole cross-sectional shape of the fitting hole of the impeller is formed into a curved surface shape which is the same shape as the fitting part of the other end portion of the drive shaft.   
     
     
         4 . The water pump as claimed in  claim 3 , wherein:
 the cross-sectional shape of the fitting part of the other end portion of the drive shaft is formed into a smooth recessed and bulging shape, and the cross-sectional shape of the fitting hole of the impeller is formed into a smooth recessed and bulging shape which is the same shape as the fitting part of the other end portion of the drive shaft.   
     
     
         5 . The water pump as claimed in  claim 4 , wherein:
 the synthetic resin material forming the drive shaft contains glass fiber, and the glass fiber existing close to an outer peripheral surface of the drive shaft is oriented along an axial direction of the drive shaft.   
     
     
         6 . The water pump as claimed in  claim 5 , wherein:
 the cross-sectional shape of the fitting part of the other end portion of the drive shaft is formed into a shape whose cross section is symmetrical about a shaft center of the drive shaft, and the cross-sectional shape of the fitting hole of the impeller is formed into a shape whose cross section is symmetrical about a center of the impeller.   
     
     
         7 . The water pump as claimed in  claim 3 , wherein:
 the cross-sectional shape of the fitting part of the other end portion of the drive shaft is formed into an oval shape, and the cross-sectional shape of the fitting hole of the impeller is formed into an oval shape which is the same shape as the fitting part of the other end portion of the drive shaft.   
     
     
         8 . The water pump as claimed in  claim 1 , wherein:
 the cross-sectional shape of the fitting part of the other end portion of the drive shaft is formed into a polygonal shape, and the cross-sectional shape of the fitting hole of the impeller is formed into a polygonal shape which is the same shape as the fitting part of the other end portion of the drive shaft.   
     
     
         9 . The water pump as claimed in  claim 8 , wherein:
 the polygonal shape is a hexagonal shape.   
     
     
         10 . The water pump as claimed in  claim 8 , wherein:
 the polygonal shape is a quadrangle shape.   
     
     
         11 . The water pump as claimed in  claim 1 , wherein:
 the other end portion of the drive shaft protrudes from the fixing member.   
     
     
         12 . The water pump as claimed in  claim 11 , wherein:
 the fixing member is fixed to the outer peripheral surface of the drive shaft by point-contact or line-contact.   
     
     
         13 . The water pump as claimed in  claim 12 , wherein:
 the fixing member is a snap ring.   
     
     
         14 . The water pump as claimed in  claim 13 , wherein:
 the snap ring is a push-nut.   
     
     
         15 . The water pump as claimed in  claim 1 , wherein:
 the drive shaft is formed into a tapered shape whose diameter becomes larger toward the pulley.   
     
     
         16 . A water pump comprising:
 a pump housing having, one end side in an axial direction thereof, a cylindrical portion;   a drive shaft rotatably supported in the pump housing and formed with synthetic resin material;   a pulley formed with synthetic resin material and having:
 a disk-shaped end wall integrally fixed to one end portion of the drive shaft; and 
 a cylindrical base portion integrally connected to an outer peripheral edge of the end wall and encircling the cylindrical portion of the pump housing; 
   a cylindrical metal member fixed to an inner circumferential side of the cylindrical base portion of the pulley;   a bearing unit interposed between the metal member and the cylindrical portion of the pump housing and rotatably supporting the drive shaft; and   an impeller formed with synthetic resin material and fitted onto the other end portion of the drive shaft through a fitting hole provided at the impeller, and wherein   the drive shaft and the impeller are configured so that
 a restraining part that restrains a maximum fitting position of the impeller in an axial direction is provided between the other end portion of the drive shaft and the fitting hole of the impeller, 
 a fixing member that restrains an axial direction movement of the impeller positioned in the maximum fitting position in cooperation with the restraining part is provided at a tip end side of the other end portion of the drive shaft, and 
 a cross-sectional shape of a fitting part, which is fitted into the fitting hole of the impeller, of the other end portion of the drive shaft is formed as a rotation restraining part, and a cross-sectional shape of the fitting hole of the impeller is formed into the same cross-sectional shape as the fitting part of the other end portion of the drive shaft, as the rotation restraining part. 
   
     
     
         17 . A method for assembling a water pump, the water pump having a drive shaft inserted and located in an inside of a pump housing and formed with synthetic resin material; a pulley provided at one end portion of the drive shaft, rotating integrally with the drive shaft and configured to rotate by transmission of power from a drive source; an impeller formed with synthetic resin material and fitted onto the other end portion of the drive shaft; and a hollow fixing member fixed to the other end side of the drive shaft with respect to the impeller, the method comprising:
 fitting the impeller onto the other end portion of the drive shaft from a tip end of the other end portion of the drive shaft in an axial direction of the drive shaft and pushing the impeller up to a position in which a movement of the impeller toward the pulley is restrained by a restraining part provided between the impeller and the drive shaft; and   fitting the fixing member onto the other end portion of the drive shaft from the tip end, which protrudes from the impeller, of the other end portion of the drive shaft in the axial direction and fixing the fixing member to the other end portion of the drive shaft at a front end surface position of the impeller.   
     
     
         18 . The method for assembling the water pump as claimed in  claim 17 , wherein:
 the fixing member is fitted onto the other end portion of the drive shaft from the tip end of the other end portion of the drive shaft in the axial direction and engaged with the other end portion of the drive shaft.   
     
     
         19 . The method for assembling the water pump as claimed in  claim 18 , wherein:
 the fixing member is engaged with and fixed to the other end portion of the drive shaft by bite of a nail portion formed on an inner circumferential side of the fixing member into the other end portion of the drive shaft.