Method of controlling a fuel supply system

Patent metadata

Field	Value
Publication number	US-9453489-B2
Application number	US-201414164514-A
Country	US
Kind code	B2
Filing date	Jan 27, 2014
Priority date	Feb 14, 2013
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

A system and method for controlling a fuel supply system of an engine is disclosed in which an engine driven high pressure fuel pump is operated whenever possible at one of an optimum demand level providing optimum pump efficiency for the current engine speed or at a zero demand level to reduce the fuel used by the engine to drive the high pressure fuel pump. The operating mode used is dependent upon at least one of the amount of fuel currently stored in a high pressure fuel accumulator and whether a current fuel demand Fd exceeds an optimum quantity Po of fuel that can be provided by the high pressure fuel pump when operating at the current engine speed.

First claim

The invention claimed is:

1. A method, comprising:
operating an engine driven fuel pump at one of a zero demand level and an optimum demand level while using a valve to control a fuel flow from the fuel pump and an accumulator to meet an engine fuel demand; and
operating the fuel pump above its optimal level when the accumulator is empty and the fuel demand is greater than fuel available from the optimally operated fuel pump, including operating the fuel pump inefficiently compared to the optimal level to provide fuel to only an engine while preventing flow to the accumulator.

2. The method of claim 1 , further comprising determining a current fuel level in the accumulator, the fuel demand from the engine, and a current fuel quantity available from the fuel pump when operating at the optimum demand level while controlling the fuel flow to the engine from the fuel pump and the accumulator to meet the fuel demand from the engine.

3. The method of claim 1 , wherein, if an amount of fuel in the accumulator is below a predefined threshold and the fuel demand from the engine is less than a current fuel quantity available from the fuel pump when operating at the optimum demand level, the fuel pump is operated at the optimum demand level and any excess fuel is supplied from the fuel pump to the accumulator.

4. The method of claim 1 , wherein, if an amount of fuel in the accumulator is above a predefined threshold, the fuel pump is operated at the zero demand level and fuel is supplied to the engine from the accumulator to meet the fuel demand from the engine.

5. The method of claim 1 , wherein, if an amount of fuel in the accumulator is between a predefined lower threshold and a predefined upper threshold and the fuel demand from the engine is more than a current fuel quantity available from the fuel pump when operating at the optimum demand level, the fuel pump is operated at the zero demand level and fuel is supplied to the engine from the accumulator to meet the fuel demand from the engine.

6. The method of claim 1 , wherein, if an amount of fuel in the accumulator is between a predefined lower threshold and a predefined upper threshold and the fuel demand from the engine is one of more than and equal to a current fuel quantity available from the fuel pump when operating at the optimum demand level, the fuel pump is operated at the zero demand level and fuel is supplied to the engine from the accumulator to meet the fuel demand from the engine.

7. The method of claim 1 , wherein, if an amount of fuel in the accumulator is above a predefined threshold and the fuel demand from the engine is more than a current fuel demand from the fuel pump when operating at the optimum demand level, the fuel pump is operated at the optimum demand level and fuel is supplied to the engine from the accumulator to meet the fuel demand from the engine.

8. An engine fuel supply system comprising:
a fuel reservoir;
a low pressure fuel pump to supply fuel from the reservoir to an engine driven high pressure fuel pump;
at least one fuel injector to supply fuel at high pressure to an engine;
a fuel accumulator to store fuel at high pressure;
a valve means to control a flow of fuel between the high pressure fuel pump, the accumulator, and the engine; and
an electronic controller to control an operation of the high pressure fuel pump, the valve means, and the at least one fuel injector, wherein the electronic controller operates the high pressure fuel pump at one of a zero demand level and an optimum demand level and uses the valve means to control the flow of fuel to the engine from the high pressure fuel pump and the accumulator to meet a fuel demand from the engine unless the accumulator is empty and the fuel demand from the engine is greater than an amount of fuel available from the high pressure fuel pump when operated at the optimum demand level, including operating the high pressure fuel pump inefficiently compared to the optimum demand level to provide fuel to only the engine while preventing flow to the accumulator.

9. The system of claim 8 , wherein the electronic controller is further operable to estimate a current fuel level in the accumulator, estimate the fuel demand from the engine, and estimate a current fuel quantity available from the high pressure fuel pump when operating at the optimum demand level while controlling the flow of fuel to the engine from the high pressure fuel pump and the accumulator to meet the fuel demand from the engine based upon at least one of the amount of fuel stored in the accumulator and a comparison of the current fuel quantity available from the high pressure fuel pump when operating at the optimum demand level with the fuel demand from the engine.

10. The system of claim 8 , wherein, if the amount of fuel in the accumulator is below a predefined threshold and the fuel demand from the engine is less than a current fuel quantity available from the high pressure fuel pump when operating at the optimum demand level, the electronic controller operates the high pressure fuel pump at the optimum demand level while controlling the valve means so that any excess fuel is supplied from the high pressure fuel pump to the accumulator.

11. The system of claim 8 , wherein, if the amount of fuel in the accumulator is above a predefined threshold, the electronic controller operates the high pressure fuel pump at the zero demand level and operates the valve means to permit fuel to be supplied to the engine from the accumulator to meet the fuel demand from the engine.

12. The system of claim 8 , wherein, if the amount of fuel in the accumulator is between a predefined lower threshold and a predefined upper threshold and the fuel demand from the engine is more than a current fuel quantity available from the high pressure fuel pump when operating at the optimum demand level, the electronic controller operates the high pressure fuel pump at the zero demand level and operates the valve means to supply fuel from the accumulator to the engine to meet the fuel demand from the engine.

13. The system of claim 8 , wherein, if the amount of fuel in the accumulator is between a predefined lower threshold and a predefined upper threshold and the fuel demand from the engine is one of more than and equal to a current fuel quantity available from the high pressure fuel pump when operating at the optimum demand level, the electronic controller operates the high pressure fuel pump at the zero demand level and operates the valve means so that fuel is supplied to the engine from the accumulator to meet the fuel demand from the engine.

14. The system of claim 8 , wherein the accumulator is a bellows type of accumulator that comprises a body having a flow passage to allow fuel to enter or leave a storage volume, the storage volume being defined by a cup shaped piston, a metal bellows, and the body, wherein the piston supports the metal bellows and is slidingly supported by the body, and wherein the metal bellows is configured to be sealed to both the body and the piston so no fuel can leak from the accumulator.

15. A motor vehicle having an engine and a fuel supply system, comprising:
a fuel reservoir;
a low pressure fuel pump to supply fuel from the fuel reservoir to an engine driven high pressure fuel pump;
at least one fuel injector to supply fuel at high pressure to the engine;
a fuel accumulator to store fuel at high pressure;
a valve means to control a flow of fuel between the engine driven high pressure fuel pump, the fuel accumulator, and the engine; and
an electronic controller to control an operation of the engine driven high pressure fu

Assignees

• Ford Global Tech Llc

Inventors

• Kees Donatus Andreas Josephine
• Lane Stuart Anthony

Classifications

• F02D2200/0602

  Fuel pressure · CPC title

• F02D41/3845 Primary

  by controlling the flow into the common rail, e.g. the amount of fuel pumped · CPC title

• F02M55/04

  Means for damping vibrations {or pressure fluctuations} in injection pump inlets {or outlets} · CPC title

• F02D41/38 Primary

  of the high pressure type · CPC title

• F02M69/46 Primary

  Details, component parts or accessories not provided for in, or of interest apart from, the apparatus covered by groups F02M69/02 - F02M69/44 · CPC title