FUEL INJECTION SYSTEM COMPRISING A VARIABLE FLOW RATE HIGH-PRESSURE PUMP

• US 20090064971A1
• Filed: 01/29/2008
• Published: 03/12/2009
• Est. Priority Date: 09/11/2007
• Status: Active Grant

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: C.R.F. Consortile Per Azioni
• Inventors: Ricco, Mario, Stucchi, Sergio, De Michele, Onofrio, Lisbona, Mariagrazia
• Granted Patent: US 7,779,815 B2
• Time in Patent Office: Days
• US Class Current: 123/446
• CPC Class Codes: F02D 2250/04 Fuel pressure pulsation in common rails
• CPC Class Codes: F02D 41/3845 by controlling the flow into the common rail, e.g. the amount of fuel pumped
• CPC Class Codes: F02M 59/06 with cylinders arranged radially to driving shaft, e.g. in V or star arrangement
• CPC Class Codes: F02M 59/102 Mechanical drive, e.g. tappets or cams F02M45/063 takes precedence
• CPC Class Codes: F02M 59/205 Quantity of fuel admitted to pumping elements being metered by an auxiliary metering device
• CPC Class Codes: F02M 59/366 Valves being actuated electrically
• CPC Class Codes: F02M 63/0225 Fuel-injection apparatus having a common rail feeding several injectors F02M63/0003 takes precedence; Means for varying pressure in common rails; Pumps feeding common rails

Abstract

An injection system includes a high-pressure pump with at least one pumping element operated in a reciprocating manner by corresponding intake and discharge strokes. Each pumping element is equipped with a corresponding intake valve in communication with an intake line, fed by a low-pressure pump. An on-off solenoid valve is positioned on the intake line of the pump and is controlled by a control unit with a frequency equal to a whole multiple or submultiple of that of the pumping action, multiplied by a factor different from 1 and/or between 0.90 and 1.10, inclusive.

Claims

1. A fuel injection system for an internal combustion engine, comprising

a variable flow rate high-pressure pump having at least one pumping element operated in a reciprocating manner by means of intake and discharge strokes, said pumping element having an intake valve in fluid communication with an intake line and a delivery valve in fluid communication with a delivery line (8);

a throttle device to control a flow rate of the pump including a metering solenoid valve positioned on said intake line to meter the quantity of fuel fed to said pumping element; and

a control unit able to control said solenoid valve during the intake phase of said pumping element based on operating conditions of the engine, said control unit operating said solenoid valve with a frequency equal to a whole multiple or submultiple of the activation frequency of said pumping element multiplied by a factor other than 1.

2. The fuel injection system according to claim 1, wherein said high-pressure pump includes two or more pumping elements operated in sequence during a pump cycle, said pump being operated with a preset pump frequency, characterized in that said solenoid valve is operated with a frequency equal to a whole multiple or submultiple of the frequency of the pump multiplied by a factor other than 1.

3. The fuel injection system according to claim 1, characterized in that said solenoid valve is operated during the intake phase of a pumping element.

4. The fuel injection system according to claim 3, characterized in that said whole multiple is 1.

5. The fuel injection system according to claim 1, characterized in that said factor is between 0.90 and 1.10 inclusive

6. The fuel infection system according to claim 5, characterized in that said factor differs from 1 by being at least 0.01 greater or smaller.

7. The fuel injection system according to claim 1, characterized in that said high-pressure pump includes two or more pumping elements operated by a rotating shaft synchronized with a drive shaft of said engine, said intake line being common to said pumping elements and said solenoid valve being positioned on said intake line.

8. The fuel injection system according to claim 7, characterized in that said high-pressure pump comprises two pumping elements operated in phase opposition.

9. The fuel injection system according to claim 7, characterized in that said high-pressure pump includes three pumping elements operated with 120°

phase shift from one another.

10. The fuel injection system according to claim 1, characterized in that said control unit is able to control said solenoid valve based on the pressure of the fuel detected by a corresponding pressure sensor in an accumulation volume of high-pressure fuel.

11. The fuel injection system according to claim 1, characterized in that said control unit is able to control said solenoid valve via frequency and/or duty-cycle modulated control signals.

12. The fuel injection system according to claim 11, characterized in that said control unit is able to control said solenoid valve via control signals of constant duration and emitted with variable frequency.

13. The fuel injection system according to claim 11, characterized in that said control unit is able to control said solenoid valve via control signals with frequency correlated to the speed of rotation of said pump and/or with variable duty-cycle.

14. The fuel injection system according to claim 10, characterized in that the duration of each control signal is of the order of a thousandth of a second and/or said duty-cycle varies from 2% to 95%.

15. The fuel injection system according to claim 1, in which said high-pressure pump includes a sump in which pump drive mechanisms are housed, characterized in that said throttle device includes a pressure regulator positioned in parallel to said metering solenoid valve, which is able to maintain pressure upstream of said solenoid valve constant and to send excess fuel to said sump to cool and lubricate said mechanisms.

16. A fuel injection system for an internal combustion engine, comprising:

a variable flow rate high-pressure pump having at least one pumping element operated in a reciprocating manner including intake and discharge strokes, said pumping element having an intake valve in fluid communication with an intake line and a delivery valve in fluid communication with a delivery line;

a throttle device operatively coupled to the pump to control a flow rate thereof, the throttle device including a metering solenoid valve positioned on said intake line to meter the quantity of fuel fed to said pumping element; and

a control unit configured to control said solenoid valve during the intake phase of said pumping element based on operating conditions of the engine, said control unit operating said solenoid valve with a frequency equal to a whole multiple or submultiple of the activation frequency of said pumping element multiplied by a factor between 0.90 and 1.10, inclusive.