Pump structure for urea scr system

Abstract

A pump unit for a urea-SCR system may use a fuel pump of a vehicle engine and may have a case portion surrounding a motor portion and a pump portion. The motor portion may include a barrier wall surrounding a rotator so as to separate the rotator from a stator of the motor portion, and the pump portion includes a shield in which a suction hole and a supply hole for fluid are formed and that is disposed between the pump portion and the motor portion so as to prevent fluid from leaking into the motor portion, so the motor is protected from the urea solution to prevent corrosion thereof, manufacturing cost is reduced, and noise caused by the vibration is reduced.

What is claimed is: 
     
         1 . A pump unit for a urea-SCR system that uses a fuel pump of a vehicle engine, the pump unit comprising:
 a case portion surrounding a motor portion and a pump portion;   wherein the motor portion includes a barrier wall surrounding a rotator so as to separate the rotator from a stator of the motor portion; and   the pump portion includes a shield in which a suction hole and a supply hole for fluid are formed and that is disposed between the pump portion and the motor portion so as to prevent fluid from leaking into the motor portion.   
     
     
         2 . The pump unit for a urea-SCR system of  claim 1 , wherein the barrier wall is made of a corrosion prevention material. 
     
     
         3 . The pump unit for a urea-SCR system of  claim 1 , wherein the pump portion is made up of one of an inscribed gear pump, a circumscribed gear pump, and a gerotor pump. 
     
     
         4 . The pump unit for a urea-SCR system of  claim 1 , wherein a center hole is formed in the shield, and a shaft of the fuel pump penetrates the center hole to connect to the motor portion. 
     
     
         5 . The pump unit for a urea-SCR system of  claim 4 , wherein a bearing is disposed between the shaft and the center hole and between the shaft and the barrier wall. 
     
     
         6 . The pump unit for a urea-SCR system of  claim 5 , wherein an O-ring is disposed between the bearing and the shield to prevent leakage of the fluid. 
     
     
         7 . The pump unit for a urea-SCR system of  claim 1 , wherein the case portion includes a main case surrounding a side surface of the motor portion and the pump portion and an upper case covering an upper portion of the motor portion. 
     
     
         8 . The pump unit for a urea-SCR system of  claim 7 , wherein the barrier wall is integrally formed with the main case. 
     
     
         9 . The pump unit for a urea-SCR system of  claim 7 , wherein the barrier wall has a cylindrical shape of which the upper portion thereof is closed, and a flange is formed at a lower portion of the barrier wall, wherein the barrier wall is engaged with a circular end portion that is formed along an interior circumference of the main case through the flange. 
     
     
         10 . The pump unit for a urea-SCR system of  claim 9 , wherein a groove is formed at an upper surface of the end portion so as to prevent the fluid from leaking between the end portion and the flange, and an O-ring is inserted into the groove. 
     
     
         11 . The pump unit for a urea-SCR system of  claim 1 , wherein the motor portion is a brushless direct current (BLDC) motor. 
     
     
         12 . The pump unit for a urea-SCR system of  claim 1 , further comprising a cover surrounding an exterior circumference of the rotator so as to prevent corrosion of the rotator. 
     
     
         13 . The pump unit for a urea-SCR system of  claim 12 , wherein the cover is formed by over-molding a plastic material. 
     
     
         14 . The pump unit for a urea-SCR system of  claim 2 , wherein the corrosion prevention material is an SUS material.