![]() The problem here was that, "we couldn't do that without the engine running," Stec said. Vacuum pump system to check for leaks, GM uses the temperature decay profile to determine if there are any holes in the system. GM has proprietary leak check diagnostics that are used on The General's more conventional vehicles. Since the Volt uses gas, drivers were going to have to open it up at some point to refuel it, so "we had to develop a whole new control process to unseal the tank without getting any hydrocarbons in the atmosphere and allow the customer to refuel the tank," Stec said. Of course, if your fuel tank can't be sealed all the time. "All the OEMs, as far as I know, are going to pursue this technology." "It had to be an agreement between all the OEMs, and it was resolved three or four years ago that we do this process (use a sealed system)," Stec said. The reason that GM worked with others to develop this system was because having each manufacturer come forward with its own proposal and hoping that the regulations concerning the tank emissions were flexible enough to allow for the different solutions seemed unlikely. This time around, the OEMs involved collectively decided to make a pressurized vessel, to seal it and then to give the the powertrain the controllers to open and close the system. "That didn't work so well for them," Stec said. Toyota tried a bladder tank, where there was an outer shell with a flexible shell on the inside that would shrink to try an reduce the space where vapors could form and deal with emissions this way. GM knew other technologies were possible. "This time," Stec said, "we don't have the engine running all the time, so what do you do? Do you put a gargantuan canister down there and hope that whatever hydrocarbons you're going to develop – typically because of temperature changes and fuel fill – will be caught? That's not very feasible." Typically, in a standard vehicle, the fuel system captures errant hydrocarbons in a canister and, when the engine runs, it purges that canister. The most important thing to figure out was how to handle evaporativeĮmissions and prevent hydrocarbons from getting into the air. "We knew early on that it was a fast program," he said, and so GM began talking with other OEMs and CARB to figure out how to design a fuel system that would work with a plug-in vehicle, because a conventional system wouldn't work. New vehicle programs at GM, which typically take 36 months or more. Stec said that the Volt program, at just 29 months, was much faster-paced than most Recently, we spoke with Jon Stec, fuel system integration engineer for the Volt, about the sealed tanks came to be. Read on past the jump for the tasty details. ![]() ![]() That's why a special sealed steel tank was developed. In the Volt, though, the engine could potentially remain off for a very long time even under daily use – up to six weeks, before the Volt's "maintenance mode" automatically kicks in. Standard vehicles use charcoal canisters to trap the gas, and then return it to the tank once the engine starts running. They also needed to figure out how to keep fuel from simply evaporating away. General Motors about the new powertrain developed for this car (and others, likeĪ plug-in Cadillac SRX, maybe), but now we've got the scoop on the gas tank used to keep liquid fuel in the Volt from evaporating or going stale for up to a year.Ĭan move without gas in the tank, but that's only part of the problem that Over the years, we've heard a lot of information from 2011 Chevy Volt – Click above for high-res image galleryĬhevrolet Volt is nothing if not a very complex engineering project. ![]()
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