US 7,252,068 B2 · System and method to reduce fuel system pumping heat input

Abstract

The present invention discloses a relatively simple system and method to reduce fuel system pumping by automatically turning on and off servo flow to various non-needed devices or “start lockout” servos during engine start. The invention takes advantage of a fuel pressure rise provided by the fuel pump during the period from engine start until the pump speed is greater than windmill. This pressure rise is used to move a pressure activated piston in a servo shutoff valve from a normally closed position to an open position, which at higher pressures allow servo flow to the “start lockout” servos through the servo lockout valve. When the pressure is reduce, the piston return to a normally closed position due to a biasing spring closing the servo lockout valve. This opening and closing of the servo lockout valve occurs automatically with no other external input.

Claims29

Dependent claims

A servo lockout valve for use in a servo lockout system coupled to a fuel pump, comprising:

a body having a first fluid inlet, a first fluid outlet, a second fluid inlet, and a second fluid outlet, the first fluid inlet and the first fluid outlet configured to communicate with the servo lockout system, and the second fluid inlet and second fluid outlet configured to communicate with the fuel pump;
and
a pressure activated piston slideably positioned within the body, the piston including an outer surface, an annular passage, and an orifice, the annular passage and the orifice formed on the piston outer surface, wherein the piston is configured to respond to fuel pressure entering the second fluid inlet to move the piston between a first position and a second position based on the fuel pressure, wherein in the first position the first fluid inlet and the first fluid outlet are not in fluid communication and the second fluid inlet, the orifice, and the second fluid outlet are in fluid communication, and in the second position the first fluid inlet, the annular passage, and the first fluid outlet are in fluid communication and the second fluid inlet and the second fluid outlet are in fluid communication.

Dependencies are inferred from the claim text.

System and method to reduce fuel system pumping heat input

Life of this patent

System and method to reduce fuel system pumping heat input

Life of this patent

Abstract

Claims29