Patent ID: 9140190
Filing Date: 2015-09-22
Classification: F02C,Y10T

Abstract:
1. A fuel metering unit, comprising: a fuel metering valve adapted to receive a flow of fuel from a fuel source and having a variable area flow orifice through which fuel from the fuel source flows, the fuel metering valve including a first control port, a second control port, and a third control port, the first control port adapted to receive hydraulic fluid at a first hydraulic fluid pressure, the second control port adapted to receive hydraulic fluid at a second hydraulic fluid pressure, the third control port adapted to selectively receive hydraulic fluid at either the first hydraulic fluid pressure or the second hydraulic fluid pressure, the fuel metering valve configured, in response to fluid pressure at the third control port, to selectively adjust the area of the variable area flow orifice; a flow increase valve in fluid communication with the fuel metering valve and adapted to receive hydraulic fluid at the first hydraulic fluid pressure, the flow increase valve adapted to selectively receive fuel flow increase commands from a primary fuel flow command source and from a secondary fuel flow command source, the flow increase valve responsive to the fuel flow increase commands to selectively supply hydraulic fluid at the first hydraulic fluid pressure to the third control port to thereby increase the area of the variable area flow orifice; and a flow decrease valve in fluid communication with the fuel metering valve and adapted to receive hydraulic fluid at the second hydraulic fluid pressure, the flow decrease valve adapted to selectively receive fuel flow decrease commands from the primary fuel flow command source and from the secondary fuel flow command source, the flow decrease valve responsive to the fuel flow decrease commands to selectively supply hydraulic fluid at the second hydraulic fluid pressure to the third control port to thereby decrease the area of the variable area flow orifice.