Patent ID: 6796772
Filing Date: 2004-09-28
Classification: F04F

Abstract:
A negative pressure supply apparatus comprising:an air outlet port connected to a negative pressure source; an air inlet port open to the atmosphere; a negative pressure port connected to a negative pressure chamber of a negative pressure device; a passage for providing communication between said air outlet port and said negative pressure port; a first check valve for allowing air to flow through said passage only in a direction from said negative pressure port to said air outlet port; an ejector having an air outlet communicating with said air outlet port, an air inlet communicating with said air inlet port, and a negative pressure outlet communicating with said negative pressure port; a second check valve for allowing air to flow only in a direction from said negative pressure port to said negative pressure outlet; and a control valve for selectively opening or closing either the air outlet or the air inlet of said ejector; wherein said control valve operates in response to a negative pressure at said negative pressure port such that said control valve is open until the negative pressure reaches a predetermined negative pressure, and when said negative pressure has reached the predetermined negative pressure, said control valve is closed rapidly.