Filler neck apparatus for preventing fuel from mixing

filler neck apparatus for preventing fuel from mixing, comprising:

• a housing into which a fuel filling gun is selectively inserted;
• a rotation protrusion that is pivotally mounted on a side of the housing and elastically biased in a direction, wherein the rotation protrusion contacts with the fuel filling gun while the fuel filling gun is inserted into the housing;
• a slider slidably installed in the housing and elastically biased in a direction wherein the slider is selectively coupled to the rotation protrusion, and wherein a locked state of the slider is released by action of the rotation protrusion and is movable in a direction when the slider is released from the rotation protrusion;
• a flapper that is pivotally mounted on a bottom end of the housing and opens or closes the bottom end of the housing by the fuel filling gun;
• a stopper that is pivotally mounted on the bottom end of the housing and selectively lock the flapper;
• and
• a link that pivotally connects the slider and the stopper,
• wherein the rotation protrusion includes:
• an upper protrusion part pivotally mounted to the housing and a portion of the upper protrusion part is inserted into the housing through an opening formed in a side of the housing;
• a lower connection part that protrudes downwardly from a bottom surface of the upper protrusion part;
• and
• a hanging jaw that protrudes from a bottom end of the lower connection part and is selectively inserted in and fastened to a hanging hole of the slider so that the slider is selectively prevented from descending.