A special fuel tank for a new kind of car
Today marks three weeks since I took delivery of my Chevy Volt and I still have about half of the original tank of gas that came with the car. Some have asked me what happens to the quality of fuel after sitting in the car for that long. I didn't know the answer until I saw a press release from GM today.
The 9.3 gallon tank in the Chevy Volt is constructed from steel, not plastic. It's also pressure sealed to keep the gas from evaporating. Here's more on the fuel system from the GM press release:
For the last several decades, new vehicles have been equipped with charcoal canisters to trap evaporating gasoline and then feed it back to the engine. Since the Volt's engine may not fire up for extended periods, hydrocarbons potentially could build up in the canister, so the sealed tank contains the vapor. The extra pressure meant that a lightweight steel tank had to replace the lightweight plastic tanks used in most modern vehicles.
Volt engineers and supplier Spectra Premium Inc. developed the tank from 1.4 millimeter thick hot-dip tin-zinc coated steel to resist corrosion from both inside and outside. Despite the strength of the tank, it has a mechanical pressure relief valve that begins opening at 3.5 psi and a vacuum relief that opens at -2.3 psi, levels that are rarely exceeded.
At some point the engine will need to run, so a maintenance mode was added. If a driver goes six weeks without using the gas engine, the Volt's computer will turn it on for a short while to keep the engine in a healthy condition. If the car goes without a gas stop for an entire year, it'll run the engine until the old fuel is consumed or additional fresh fuel is added to the tank.
Yet another example of the kind of engineering that had to go into the design of this vehicle.
