Pump Driving Apparatus

Abstract

A pump driving apparatus that can suppress backflow of a liquid in a pump chamber and improve pump efficiency is provided. A guide tube 23 is provided coaxially with an output shaft 4 of a motor M inside a pump chamber 8, and the ends in the axial direction of the guide tube 23 are fitted into and make sliding contact with a case inner wall surface that forms the pump chamber 8 and a shaft core-side inner wall surface 25 of an impeller 9 enclosed inside the pump chamber 8.

1 . A pump driving apparatus that draws in a liquid in an axial direction into a pump chamber and expels the liquid in the circumferential direction using an impeller that is magnetically coupled to a rotor of a motor and rotates about a fixed shaft,
 the pump driving apparatus comprising a guide tube that is provided inside the pump chamber so as to be coaxial with the fixed shaft, wherein ends of the guide tube in the axial direction are fitted to and make sliding contact with a case wall surface that forms the pump chamber and a core-side wall surface of the impeller enclosed inside the pump chamber.   
   
   
       2 . A pump driving apparatus according to  claim 1 ,
 wherein surfaces of the guide tube that make sliding contact are spherical surface portions which are produced by having an outer circumferential surface of the guide tube swell outward and whose respective centers lie on an axis of the fixed shaft, and both ends of the guide tube in the axial direction are fitted into and make sliding contact with the pump case and an uprising wall surface of the impeller.   
   
   
       3 . A pump driving apparatus according to  claim 1 ,
 wherein surfaces of the pump case and the impeller that make sliding contact are spherical surface portions that are each produced by having an outer circumferential surface of an erected wall, which is erected in the axial direction inside the pump chamber, swell outward and whose centers lie on an axis of the fixed shaft, and are fitted into a tube hole of the guide tube so as to make the sliding contact.   
   
   
       4 . A pump driving apparatus according to  claim 1 ,
 wherein at one end in the axial direction, a spherical surface portion that is produced by having an outer circumferential surface of an erected wall, which is erected in the axial direction inside the pump chamber, swell outward and whose center lies on an axis of the fixed shaft is formed on one of the pump case and the impeller and the spherical surface portion is fitted into a tube hole of the guide tube so as to make sliding contact, and at another end in the axial direction, a spherical surface portion that is produced by having an outer circumferential surface of the guide tube swell outward and whose center lies on the axis of the fixed shaft is formed on the guide tube and the spherical surface portion is fitted into an erected wall of one of the pump case and the impeller.