Urea solution pump structure

Abstract

A urea solution pump structure may include a housing portion connected to an external connector and covering an upper portion of the pump structure, a motor portion disposed at a lower portion of the housing portion and including a rotor and a stator, a case portion receiving the motor portion therein, and a pump portion disposed at a lower portion of the case portion and fluid-isolated from the motor portion, wherein the pump portion may be formed with an inlet and an outlet for a fluid, wherein a hollow cover may be provided at a lower portion of the case portion for separating the pump portion and the motor portion, and an oil seal unit may be mounted at a lower portion of the hollow cover for sealing a rotating shaft of the rotor which penetrates through the hollow cover.

What is claimed is: 
     
         1 . A urea solution pump structure, comprising:
 a housing portion connected to an external connector and covering an upper portion of the pump structure;   a motor portion disposed at a lower portion of the housing portion and including a rotor and a stator;   a case portion receiving the motor portion therein; and   a pump portion disposed at a lower portion of the case portion and fluid-isolated from the motor portion, wherein the pump portion is formed with an inlet and an outlet for a fluid,   wherein a hollow cover is provided at a lower portion of the case portion for separating the pump portion and the motor portion, and an oil seal unit is mounted at a lower portion of the hollow cover for sealing a rotating shaft of the rotor which penetrates through the hollow cover.   
     
     
         2 . The urea solution pump structure of  claim 1 , wherein the oil seal unit includes:
 a fixed element mounted under the hollow cover and enclosing the rotating shaft of the motor portion;   a rotating element fixed to the rotating shaft to rotate with the rotating shaft;   a pressing element disposed under the rotating element and elastically biased toward the rotating element.   
     
     
         3 . The urea solution pump structure of  claim 2 , wherein a damping space is formed between an interior circumference of the pump portion and the rotating element of the oil seal unit. 
     
     
         4 . The urea solution pump structure of  claim 1 , wherein the oil seal unit is a mechanical seal. 
     
     
         5 . The urea solution pump structure of  claim 4 , wherein a damping space is formed between an interior circumference of the pump portion and an exterior surface of the mechanical seal. 
     
     
         6 . The urea solution pump structure of  claim 5 , wherein the pump portion includes a gear box being a main body of the pump portion, a gear pump mounted at a groove formed on a lower portion of the gear box, and a lower panel covering a lower surface of the gear box and formed with the inlet and the outlet, and the damping space is formed between an interior circumference of the gear box and the mechanical seal. 
     
     
         7 . The urea solution pump structure of  claim 6 , wherein a filler is provided in the damping space for absorbing expansion of a urea solution. 
     
     
         8 . The urea solution pump structure of  claim 6 , wherein the filler is compressible. 
     
     
         9 . The urea solution pump structure of  claim 7 , wherein
 a drain hole is formed or a relief valve is mounted at a lower surface of the damping space in the gear box close to the inlet for preventing overpressure of the fluid.   
     
     
         10 . The urea solution pump structure of  claim 9 , wherein the drain hole or the relief valve is formed between the damping space and the inlet and connected to the inlet. 
     
     
         11 . The urea solution pump structure of  claim 1 , wherein a bearing is provided at an upper portion of the case portion for supporting the rotation of the rotating shaft. 
     
     
         12 . The urea solution pump structure of  claim 5 , wherein the pump portion includes a main body portion which forms the damping space, a gear pump portion which is engaged at a lower portion of the main body portion and of which a gear pump is provided with therein, and a lower panel covering a lower surface of the gear pump portion and connecting to the gear pump portion being formed with the inlet and the outlet.