Valve assembly

摘要

A valve assembly suitable for use as an inlet metering valve of a fuel injection system comprises an inlet opening, an outlet aperture, and a valve element arranged to control fluid flow between the inlet opening and the outlet aperture. The valve element is moveable in response to an applied control signal to a closed position and to a fully-open position, and is biased to return to a rest position when the control signal is absent. When the valve element is in the rest position, fluid flow between the inlet opening and the outlet aperture is permitted at a relatively low rate. When the valve element is in the closed position, fluid flow between the inlet opening and the outlet aperture is substantially prevented. When the valve element is in the fully-open position, fluid flow between the inlet opening and the outlet aperture is permitted at a relatively high rate.

主权项

1. A valve assembly comprising:
a valve body having a bore; an inlet opening defined in the valve body; an outlet aperture; and a valve element received in the bore and arranged to control fluid flow between the inlet opening and the outlet aperture, the valve element being moveable linearly between a rest position (A) where it abuts a shoulder and a fully-open position (D) where it abuts an end surface; wherein the valve element is moveable from the rest position (A) into a closed position (B) on application of a first control signal and towards the fully-open position (D) on application of a second control signal, the magnitude of the second control signal being greater than the magnitude of the first control signal and the valve element is biased to return to the rest position (A) when no control signal is present; and wherein: when the valve element is in the rest position (A), fluid flow between the inlet opening and the outlet aperture is permitted at a relatively low rate; when the valve element is in the closed position (B), fluid flow between the inlet opening and the outlet aperture is substantially prevented; and when the valve element is in the fully-open position, fluid flow between the inlet opening and the outlet aperture is permitted at a relatively high rate, and wherein, the valve element is configured to occlude the inlet opening when in the closed position (B), the valve element further comprising at least one bypass orifice that communicates with the outlet aperture, arranged such that the bypass orifice overlaps with the inlet opening to allow fuel to flow at the relatively low rate when the valve element is in the rest position (A).