Patent ID: 6928995

Claim:
An emission control valve for use in an emission control system of an internal combustion engine comprising: valve body structure providing an inlet port at which flow enters the valve, an outlet port at which flow exits the valve, a valve element comprising first and second closures spaced apart along an axis for respective cooperation with respective seats that are axially spaced apart to selectively seat on the respective seat for disallowing flow between the inlet port and the outlet port and to unseat from the respective seat for allowing flow between the inlet port and the outlet port, and an actuator for selectively positioning the valve element along the axis relative to the seats, wherein each seat circumscribes a respective through-hole for flow, the through-hole of one seat is large enough diametrically to allow the closure that seats on the other seat to pass through during fabrication of the valve, each through-hole comprises a respective frustoconical surface zone coaxial with the axis and tapered in the same axial direction, the closure that seats on the other seat seats substantially on a radially outermost portion of the frustoconical surface zone of the through-hole of the other seat when the valve element is disallowing flow, and the other closure seats substantially on a radially innermost portion of the frustoconical surface zone of the through-hole of the one seat when the valve is disallowing flow.