After spending the last hour on my hands and knees with my glasses off searching for a spring that slid off my q/r skewer, I am reminded why I *always* hold them in place with a dab of Super Glue. Yesterday, I replaced my SON bolt-on skewer with a Shimano q/r and as I changed tires today (deconstructing the Sherpa shimmy solution), I remembered I hadn't glued it. I removed it to do so...and got a lesson on...why I should...as I was in process.
The only purpose of these springs here is to aid in centering the q/r so wheel replacement is more convenient (and they surely do that!). The q/r will work as well and safely as always if the springs are missing, but it sure is nice to have them. Worth searching for in the grass. Worth gluing in place so you don't have to search. Gluing them to the ends of the q/r nut and cam to prevent loss is a Very Good Idea.
As to the title, a volute spring is cone-shaped and collapses on itself under pressure so when fully end-loaded, it is flat...just like the centering springs on a quick-release skewer. See: http://en.wikipedia.org/wiki/Volute_springhttp://en.wikipedia.org/wiki/Spring_%28device%29