Fuel vapor processing apparatus

A fuel vapor processing apparatus comprising:

• a first canister including a first case body that defines therein a first adsorption chamber, a second adsorption chamber and a dissipation delaying space;
• and
• a second canister including a second case body that defines therein an atmospheric-side adsorption chamber;
• wherein:
• each of the first adsorption chamber and the second adsorption chamber of the first canister contains a tank-side adsorption material;
• the atmospheric-side adsorption chamber of the second canister communicates with the dissipation delaying space and contains an atmospheric-side adsorption material;
• the first adsorption chamber of the first canister communicates with a space within a fuel tank and is configured such that that fuel vapor dissipating from the space within the fuel tank is adsorbed by the tank-side adsorption material of the first adsorption chamber as the fuel vapor flows in a first direction within the first adsorption chamber;
• the second adsorption chamber is disposed on a downstream side of the first adsorption chamber and is configured such that the fuel vapor is adsorbed by the tank-side adsorption material of the second adsorption chamber as the fuel vapor flows in a second direction within the second adsorption chamber;
• the second direction is opposite to the first direction;
• the dissipation delaying space is disposed on a downstream side of the second adsorption chamber and containing no adsorption material, so that the dissipation delaying space is capable of delaying dissipation of fuel vapor flowing from the second adsorption chamber;
• the fuel vapor dissipated within the dissipation delaying space flows in the second direction and further flows into the atmospheric-side adsorption chamber of the second canister so as to be adsorbed by the atmospheric-side adsorption material;
• the first canister further includes a first throttle and a second throttle respectively disposed at a first end and a second end of the dissipation delaying space, the first end and the second end being opposite to each other with respect to the second direction;
• the first throttle is a plurality of through holes formed in a partition plate disposed at the first end of the dissipation delaying space;
• the second throttle is a connection port provided at the first case body, so that the fuel vapor flows from the dissipation delaying space of the first canister to the atmospheric-side adsorption chamber of the second canister via the connection port;
• the dissipation delaying space has a first length along the second direction;
• the second adsorption chamber has a second length along the second direction;
• and
• the first length is longer than the second length and is longer than half a length of the first adsorption chamber along the first direction.