Patent ID: 8276569

Claim:
A fuel vapor processing apparatus comprising: a case defining an adsorption material chamber, through which fuel vapor containing gas can flow; an adsorption material filled within the adsorption material chamber; an L/D ratio setting region defined in the adsorption material chamber; wherein “L” designates a length of the L/D ratio setting region along a direction of flow of fuel vapor containing gas and “D” designates a diameter of a circular area equivalent to a cross sectional area of the L/D ratio setting region substantially perpendicular to the direction of flow of fuel vapor containing gas; and an L/D ratio setting device including an L/D ratio setting member disposed within the L/D ratio setting region so as to be surrounded by the adsorption material and capable of restricting a filling volume of the adsorption material, wherein: the case includes a tank port communicating with a fuel tank, a purge port communicating with an engine, and an atmospheric port communicating with the atmosphere, during an adsorption operation, fuel vapor containing gas generated within the fuel tank is introduced into the adsorption chamber via the tank port and flows through the adsorption chamber toward the atmospheric port, so that fuel vapor contained in the fuel vapor containing gas is adsorbed by the adsorption material; during a desorption operation, atmospheric air is introduced into the adsorption chamber via the atmospheric port and flows through the adsorption chamber toward the purge port, so that fuel vapor is desorbed from the adsorption material and is supplied to the engine via the purge port; the adsorption chamber includes an end portion facing to the atmospheric port; the L/D ratio setting region is defined at a downstream end portion of the adsorption material chamber with respect to the direction of flow of fuel vapor containing gas; the L/D ratio setting member includes an upstream end and a downstream end with respect to the direction of flow of fuel vapor containing gas, and an outer circumferential surface extending between the upstream end and the downstream end; and at least the upstream end and the outer circumferential surface have no gas communication hole.