Circuit and method for metering fuel with compensation for variations in the density of the fuel

Patent metadata

Field	Value
Publication number	US-11105271-B2
Application number	US-201716311407-A
Country	US
Kind code	B2
Filing date	Jun 27, 2017
Priority date	Jun 27, 2016
Publication date	Aug 31, 2021
Grant date	Aug 31, 2021

Abstract

A circuit for metering fuel for a turbomachine, including a fuel metering element, a pump designed to pump a flow of fuel to the metering element, and a control valve designed to return, toward the pump, an excess flow of fuel delivered to the metering element as a function of a fuel pressure difference at the terminals of the metering element, the control valve is designed to modulate the excess flow returned toward the pump as a function of variations in the density of the fuel delivered to the metering element. A turbomachine can include such a circuit.

First claim

The invention claimed is:

1. A fuel metering circuit for turbomachine, comprising:
a fuel metering element,
a pump adapted to circulate a fuel flow towards the metering element, and
a control valve adapted to return, towards the pump, an excess fuel flow delivered to the metering element, as a function of a difference in fuel pressure at terminals of the metering element,
the control valve being adapted to modulate the excess flow returned towards the pump as a function of variations in fuel density delivered to the metering element,
said fuel metering circuit further comprising a high-pressure line for feeding the metering element and a low-pressure line for returning to the pump,
wherein the control valve comprises a cylinder and an inlet orifice arranged in the cylinder and connected to the high-pressure line,
wherein said metering element comprises:
a flow extraction line connecting the high-pressure line to a chamber of the control valve, said flow extraction line comprising a pump adapted to deliver to said chamber a constant fuel flow at a pressure higher than the pressure of the fuel in the high-pressure line, and
a flow return line connecting the chamber to a fuel recirculation inlet of the high-pressure line, said flow return line comprising a diaphragm,

said flow extraction line and said flow return line ensuring the feeding of the chamber with a constant fuel flow the pressure of which is solely dependent on the fuel density.

2. The metering circuit according to claim 1 , wherein the control valve comprises:
a slide gate mobile in translation within the cylinder, and
an outlet orifice arranged in the cylinder and connected to the low-pressure line,
the control valve being conformed so that movement of the slide gate in the cylinder causes a variation in the fuel flow circulating from the inlet orifice to the outlet orifice,
the slide gate comprising two movement-controlling end sections, respectively connected to the high-pressure line and low-pressure line, and further comprising an additional movement-controlling section adapted to modulate the position of the slide gate as a function of the fuel density.

3. The metering circuit according to claim 2 , wherein the chamber of the control valve is delimited by the additional movement-controlling section of the slide gate, the pressure of the chamber being exerted on the additional movement-controlling section of the slide gate.

4. The metering circuit according to claim 2 , wherein the cylinder has first and second orifices opening into the chamber,
the flow extraction line connecting the high-pressure line and the first orifice, and the flow return line connects the second orifice to the high-pressure line.

5. The fuel metering circuit according to claim 1 , wherein the pump of the flow extraction line is a displacement pump.

6. A turbomachine, comprising a fuel metering circuit according to claim 1 .

7. A fuel metering method implemented in a fuel metering circuit according to claim 1 , the metering method comprising:
feeding the fuel metering element with a regulated fuel flow rate as a function of a difference in fuel pressure at the terminals of the metering element and as a function of the fuel density.

8. The fuel metering method according to claim 7 , wherein the controlling of the fuel flow feeding the metering element comprises recirculation of a variable fuel flow towards the pump with the control valve, and the controlling of the recirculated flow comprises the application, on a control section of said valve, of a fuel pressure solely dependent on the fuel density.

Assignees

• Safran Aircraft Engines

Inventors

• Pora Loic

Classifications

• F02C7/232 Primary

  Fuel valves {(control of fuel supply by means of fuel metering valves F02C9/263)}; Draining valves or systems (valves in general F16K) · CPC title

• F05D2270/306

  Mass flow · CPC title

• F02C9/32

  characterised by throttling of fuel (F02C9/38 takes precedence) · CPC title

• F16K11/07

  with cylindrical slides · CPC title

• F05D2270/3015

  differential pressure · CPC title