Electric pump

Abstract

A driving timing gear is located between an electric motor and a driving rotor with respect to an axial direction of a driving shaft. A first bearing is located on the same side of the driving rotor as the driving timing gear. The driving shaft has a rotor attaching end. The rotor attaching end is a free end that is located on the same side of the first bearing as the driving rotor. A weight is at a portion of the driving rotor that is close to the driving timing gear with respect to the axial direction of the driving shaft. Another weight is located at a portion of a driven rotor that is closer to a driven timing gear.

1 . An electric pump, comprising: 
 an electric motor;    a first rotary shaft driven by the electric motor;    a first rotor fixed to the first rotary shaft;    a first timing gear provided to the first rotary shaft, the first timing gear being located between the electric motor and the first rotor with respect to the axial direction of the first rotary shaft;    a first bearing supporting the first rotary shaft, the first bearing being located on the same side of the first rotor as the first timing gear, wherein the first rotary shaft has a free end that is located on the same side of the first bearing as the first rotor;    a first weight provided to the first rotor so as to rotate integrally with the first rotor, wherein the material of the first weight has a specific gravity greater than that of the material of the first rotor, and the first weight is located at a portion of the first rotor that is close to the first timing gear with respect to an axial direction of the first rotary shaft;    a second rotary shaft;    a second rotor fixed to the second rotary shaft;    a second timing gear provided to the second rotary shaft, the first timing gear and the second timing gear causing the second rotary shaft to rotate synchronously with the first rotary shaft, and the second timing gear being located between the electric motor and the second rotor with respect to an axial direction of the second rotary shaft;    a second bearing supporting the second rotary shaft, the second bearing being located on the same side of the second rotor as the second timing gear, wherein the second rotary shaft has a free end that is located on the same side of the second bearing as the second rotor; and    a second weight provided to the second rotor so as to rotate integrally with the second rotor, wherein the material of the second weight has a specific gravity greater than that of the material of the second rotor, and the second weight is located at a portion of the second rotor that is close to the second timing gear with respect to the axial direction of the second rotary shaft.    
   
   
       2 . The electric pump according to  claim 1 , 
 wherein the first rotor and the second rotor are Roots type, each of the first rotor and the second rotor having a plurality of lobes arranged at equal angular intervals along a circumferential direction of the first rotary shaft and along a circumferential direction of the second rotary shaft, respectively, and a plurality of recesses each located between an adjacent pair of the lobes,    wherein the first rotor has a first through hole extending along the axial direction, the first weight being arranged in the first through hole, and    wherein the second rotor has a second through hole extending along the axial direction, the second weight being arranged in the second through hole.    
   
   
       3 . The electric pump according to  claim 2 , 
 wherein the first rotor and the second rotor are each a two-lobe type, wherein the two lobes of the first rotor are located on opposite sides of the first rotary shaft, each lobe having the first through hole, and    wherein the two lobes of the second rotor are located on opposite sides of the second rotary shaft, each lobe having the second through hole.    
   
   
       4 . The electric pump according to  claim 1 , 
 wherein the first weight is located on an end face of the first rotor that faces the first timing gear, and    wherein the second weight is located on an end face of the second rotor that faces the second timing gear.