US Patent 7114743 Foldable baby carriage

The folding baby carriage is foldable so that four wheels approach each other back and forth and from side to side. The baby carriage includes a lower frame structure that is positioned above the four wheels to form a seating surface portion of a seat and that is foldable so as to approach back and forth and from side to side with the four wheels, and an inverted U-shaped member extending to rise upward from both sides of the seating surface portion. The inverted U-shaped member remains on a single plane in both the folded state and the opened state without bending out of this plane, but lower ends of the inverted U-shaped member come closer together in the folded state.