Pump structure

Abstract

A pump apparatus may include an inner rotor, a driving shaft, a curved surface formed at an inner circumference portion of the inner rotor into which the driving shaft may be inserted, the curved surface being formed by a plurality of curves along a rotation direction of the driving shaft, and a pressing body slidably engaged in the driving shaft and elastically pressed in a radial direction of the driving shaft by the plurality of curves.

What is claimed is: 
     
         1 . A pump apparatus, comprising:
 an inner rotor;   a driving shaft;   a curved surface formed at an inner circumference portion of the inner rotor into which the driving shaft is inserted, the curved surface being formed by a plurality of curves along a rotation direction of the driving shaft; and   a pressing body slidably engaged in the driving shaft and elastically pressed in a radial direction of the driving shaft by the plurality of curves.   
     
     
         2 . The pump apparatus of  claim 1 , wherein the curved surface of the inner rotor is formed by repeating bent straight lines and is formed at an entire portion of the inner circumference portion in the inner rotor. 
     
     
         3 . The pump apparatus of  claim 2 , wherein the curved surface of the inner rotor includes upper and lower ridges alternatively repeated between the bent straight lines. 
     
     
         4 . The pump apparatus of  claim 1 ,
 wherein the pressing body includes a spherical ball, and   wherein at least a portion of the spherical ball is slidably positioned in the driving shaft in a state in which the spherical ball is selectively pressed toward the curved surface.   
     
     
         5 . The pump apparatus of  claim 1 , further including:
 a guide groove that is formed in the driving shaft along the radial direction thereof so that the pressing body is movable along the radial direction according to a rotation of the inner rotor; and   an elastic member positioned inside the guide groove and applying elastic force to the pressing body against the inner circumference portion of the inner rotor.   
     
     
         6 . The pump apparatus of  claim 5 ,
 wherein the elastic member includes a coil spring,   wherein the pressing body includes a spherical ball, and   wherein a slide guide is placed between the elastic member and the pressing body inside the guide groove and supported by the elastic member to linearly slide in the guide groove so as to apply the elastic force provided by the elastic member to the pressing body.   
     
     
         7 . The pump apparatus of  claim 6 , wherein the pressing body includes a spherical ball.