LOW FRICTION FUEL METERING VALVE

摘要

A method of metering fuel with a fuel valve. The method includes arranging a spool within to a sleeve along an axis, wherein the spool includes four seal lands. The sleeve includes a fuel inlet aperture, a fuel outlet aperture, and a shutoff port. A first cavity and a second cavity are defined between the spool, the sleeve, and subsets of the seal lands. The fuel inlet port and the fuel outlet port abut one such cavity. Sliding the spool along the axis results in the fuel outlet aperture extending longitudinally beyond the second seal land in the upstream direction.

主权项

1. A fuel metering valve comprising:
a sleeve having an upstream end and a downstream end, the sleeve comprising:
a gear pump inlet port;a fuel inlet port arranged downstream of the gear pump inlet port;a fuel outlet port arranged downstream of the fuel inlet port;a low pressure port arranged downstream of the fuel outlet port and fluidically connected to the gear pump inlet; anda fuel shutoff port arranged downstream of the fuel outlet port; a valve spool having a stroke length along the upstream-downstream axis, the valve spool comprising:
a first land arranged to contact the sleeve downstream of the gear pump inlet port and the shutoff port;a second land arranged such that the fuel outlet port extends farther upstream than the second land, and when the fuel metering valve is in a shutdown state the second seal land extends farther in both the upstream and downstream directions than the fuel outlet port to minimize the fuel flow from upstream of the second seal land to downstream of the second seal land via the gear pump inlet port and the shutoff port;a third land arranged upstream of the fuel inlet port and downstream of the gear pump inlet; anda fourth land arranged upstream of the gear pump inlet.