US Patent 7225775 Fluid supply apparatus

A fluid supply apparatus includes a fluid pump for supplying a fluid to a fluid supplied portion from a fluid storage portion, a pair of passages provided between the fluid storage portion and the fluid supplied portion in series with the fluid pump, one of the pair of passages including a first supply passage with a check valve therein for preventing the fluid from flowing back to the fluid storage portion from the fluid supplied portion and the other of the pair of passages including a second supply passage provided in parallel with the first supply passage, and a switching apparatus for switching the second supply passage to a state in which the fluid can flow in the second supply passage.