Fuel tank system

A fuel tank system comprising:

• a feed pump module configured to draw fuel and supply the fuel;
• a controller configured to control the feed pump module;
• a main tank that accommodates the feed pump module;
• an auxiliary tank;
• a fuel introduction pipe that has a first branch pipe and a second branch pipe, wherein
• the first branch pipe has an end inserted into the main tank from above and is configured to supply the fuel to the main tank,
• the second branch pipe has an end inserted into the auxiliary tank from above and is configured to supply the fuel to the auxiliary tank,
• the fuel introduction pipe is configured such that fuel supply to the main tank through the first branch pipe is switched to fuel supply to the auxiliary tank when the main tank is filled with the fuel;
• a transfer device configured to draw fuel in the auxiliary tank and transfer the fuel to the main tank;
• a communication pipe that connects the main tank and the auxiliary tank to each other, the communication pipe having an end that is inserted into the main tank from above and an end that is inserted into the auxiliary tank from above;
• a canister that collects fuel vapor;
• a scavenging pipe that connects the canister and the auxiliary tank to each other;
• an ORVR valve, the ORVR valve being a float type valve provided at an end of the scavenging pipe located in the auxiliary tank, wherein the ORVR valve is configured to close when a liquid level of fuel reaches the ORVR valve, thereby limiting scavenging of fuel vapor from the auxiliary tank to the canister;
• a first pressure relief pipe that branches off from the scavenging pipe and has an end inserted into the main tank, wherein the first pressure relief pipe has a flow resistance of fuel vapor greater than those of the scavenging pipe and the communication pipe;
• a first cut-off valve that is a float type valve provided at the end of the first pressure relief pipe, wherein the first cut-off valve is configured to close when the liquid level of fuel reaches the first cut-off valve;
• a second pressure relief pipe that branches off from the scavenging pipe and has an end inserted into the auxiliary tank, wherein the second pressure relief pipe has a flow resistance of fuel vapor greater than that of the scavenging pipe;
• a second cut-off valve that is a float type valve provided at an end of the second pressure relief pipe, wherein the second cut-off valve is configured to close when the liquid level of fuel reaches the second cut-off valve;
• and
• a pressure relief control valve that is provided in the first pressure relief pipe, wherein the pressure relief control valve is configured to close to limit a flow of fuel vapor through the first pressure relief pipe, wherein
• in the main tank:
• the end of the communication pipe is located at a position higher than the end of the fuel introduction pipe inserted into the main tank from above, and
• the end of the first pressure relief pipe at which the first cut-off valve is provided is located at a position higher than the end of the communication pipe, and
• in the auxiliary tank:
• the end of the communication pipe is located at a position higher than the end of the fuel introduction pipe inserted into the auxiliary tank, and
• the end of the second pressure relief pipe at which the second cut-off valve is provided is located at a position higher than an end of the scavenging pipe,
• wherein when refueling is started, due to supplying the fuel to the main tank, the fuel vapor is introduced from the end of the communication pipe located at a position higher than an end of the first branching pipe and is sent to the canister through the scavenging pipe in the auxiliary tank, and
• wherein when the fuel in the main tank reaches the end of the communication pipe in the main tank and the fuel blocks the end of the communication pipe in the main tank, fuel supplying to the main tank is stopped and the fuel is supplied to the auxiliary tank through the second branching pipe, and the controller is configured to maintain the first pressure relief pipe in a closed state while refueling is performed.