Multistage oil pump

Abstract

A conventional multistage oil pump, wherein the components are formed of a ferrous material, and thus, there have been presented a problem that the weight is large. The multistage oil pump and rotors are connected in a series, wherein a rotor case, a first rotor case and a second rotor case are connected in the axial direction, and the inside thereof is partitioned by a spacer. The first rotor case and the second rotor case are jointed to the spacer with dowel pins. The rotors are formed of a ferrous material, while the spacer being formed of an aluminum-based material.

1 . A multistage oil pump, a plurality of rotors being connected in series in the direction of the rotation axis, said plurality of rotors being accommodated in a rotor case, the inside thereof being partitioned by a spacer, the rotor case being divided in the axial direction, and said spacer being made of a material having a specific gravity smaller than that for the rotor. 
     
     
         2 . The multistage oil pump according to  claim 1 , wherein said rotors are made of a ferrous material, while said spacer being made of an aluminum-based material. 
     
     
         3 . The multistage oil pump according to  claim 1 , wherein, with said rotor case, said spacer is interposed between rotor case units, the spacer and said respective rotor case units being jointed to each other by dowel pins. 
     
     
         4 . The multistage oil pump according to  claim 2 , wherein, with said rotor case, said spacer is interposed between rotor case units, the spacer and said respective rotor case units being jointed to each other by dowel pins.