Oil pump

Abstract

An oil pump including an upstream pump unit including an upstream inner rotor and an upstream outer rotor; a downstream pump unit including a downstream inner rotor and a downstream outer rotor as being arranged adjacently to the upstream pump unit in a predetermined axis line direction; a rotary shaft concurrently rotating the upstream inner rotor and the downstream inner rotor; and a housing which contains the upstream pump unit and the downstream pump unit as supporting the rotary shaft and which includes an inlet port for sucking oil from the outside into the upstream pump unit, an ejection port for ejecting a part thereof to the outside in a pressurization process of the upstream pump unit, a communication port for providing communication between the upstream pump unit and the downstream pump unit, and a discharge port for discharging oil from the downstream pump unit to the outside.

What is claimed is: 
     
         1 . An oil pump, comprising:
 an upstream pump unit which includes an upstream inner rotor and an upstream outer rotor;   a downstream pump unit which includes a downstream inner rotor and a downstream outer rotor, the downstream inner rotor and the downstream outer rotor being arranged adjacently to the upstream pump unit in a predetermined axis line direction;   a rotary shaft which concurrently rotates the upstream inner rotor and the downstream inner rotor; and   a housing which contains the upstream pump unit and the downstream pump unit and supports the rotary shaft, the housing including an inlet port configured to suck oil from the outside into the upstream pump unit, an ejection port configured to eject a part of the sucked oil to the outside in a pressurization process of the upstream pump unit, a communication port which provides communication between the upstream pump unit and the downstream pump unit, and a discharge port configured to discharge oil from the downstream pump unit to the outside.   
     
     
         2 . The oil pump according to  claim 1 , wherein the upstream pump unit is configured to have a discharge rate that is larger than a discharge rate of the downstream pump unit. 
     
     
         3 . The oil pump according to  claim 2 , wherein the upstream pump unit has a discharge rate that is equal to a sum of a discharge rate of the downstream pump unit and an ejection rate ejected through the ejection port. 
     
     
         4 . The oil pump according to  claim 3 , wherein the ejection rate ejected through the ejection port is set to be 20% or more of the discharge rate of the upstream pump unit. 
     
     
         5 . The oil pump according to  claim 1 , wherein the upstream pump unit is configured to have a thickness in the axis line direction that is larger than a thickness of the downstream pump unit in the axis line direction. 
     
     
         6 . The oil pump according to  claim 2 , wherein the upstream pump unit is configured to have a thickness in the axis line direction that is larger than a thickness of the downstream pump unit in the axis line direction. 
     
     
         7 . The oil pump according to  claim 3 , wherein the upstream pump unit is configured to have a thickness in the axis line direction that is larger than a thickness of the downstream pump unit in the axis line direction. 
     
     
         8 . The oil pump according to  claim 4 , wherein the upstream pump unit is configured to have a thickness in the axis line direction that is larger than a thickness of the downstream pump unit in the axis line direction. 
     
     
         9 . The oil pump according to  claim 1 , wherein the housing comprises:
 a housing body which includes a concave portion for containing the upstream pump unit and the downstream pump unit;   a partition member which is interposed between the upstream pump unit and the downstream pump unit; and   a housing cover with which the housing body is covered.   
     
     
         10 . The oil pump according to  claim 9 , wherein the ejection port is arranged at the housing cover,
 the communication port is arranged at the partition member, and   the inlet port is arranged at the partition member at a position opposite to the ejection port in the axis line direction as sandwiching the upstream pump unit.   
     
     
         11 . The oil pump according to  claim 10 , wherein each of the upstream pump unit and the downstream pump unit is a trochoid type having four blades and five nodes with the inner rotor and the outer rotor.