Patent ID: 6972093

Claim:
An onboard fuel separation apparatus for an automobile comprising: a separation membrane for separating a fuel supplied as a material into a high-octane fuel containing a larger amount of high octane value components than a material fuel and a low-octane fuel containing a larger amount of low octane value components than the material fuel by selectively allowing high-octane value components in the material fuel to permeate therethrough and forming a high-octane fuel on one side thereof and a low-octane fuel on the other side thereof; and a permeability increaser that increases the ratio of the amount of high-octane value components that permeate through the separation membrane to the amount of the high-octane value components contained in the fuel by regulating the temperature of the fuel supplied to the separation membrane, wherein the permeability increaser comprises a vapor-liquid separator which recovers liquid high-octane fuel by cooling the fuel vapor supplied from the high-octane fuel side of the separation membrane and, wherein the permeability increaser further comprises a vapor circulator which increases the partial pressure of the low-octane value components on the high-octane fuel side of the separation membrane by returning the vapor in the vapor-liquid separator remained after the liquid high-octane fuel has been recovered to the high-octane fuel side of the separation membrane.