Ruiz scored his team-high third goal of the season, beating goalkeeper Jon Conway from 30 yards.
Philadelphia (5-3-2) scored more than one goal in a game for the first time this season. The Union, 4-0-2 at home, had an MLS-low six goals in their first nine games.
Union rookie Michael Farfan scored his first MLS goal in the 64th minute, and Dominic Oduro tied it for Chicago (1-4-5) in the 68th minute. The Fire dropped to 0-3-3 on the road.
(Copyright 2011 Philadelphia Union. Reprinted by permission)