Controller for direct injection engine and controlling method

• US 20070028897A1
• Filed: 07/26/2006
• Published: 02/08/2007
• Est. Priority Date: 08/08/2005
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Fukasawa, Osamu
• Granted Patent: US 7,565,898 B2
• Time in Patent Office: Days
• US Class Current: 123/467
• CPC Class Codes: F02D 2250/02 Fuel evaporation in fuel rails, e.g. in common rails
• CPC Class Codes: F02D 2250/31 Control of the fuel pressure
• CPC Class Codes: F02D 41/042 for stopping the engine
• 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 59/366 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
• CPC Class Codes: F02M 65/003 Measuring variation of fuel pressure in high pressure line

Abstract

An ECU feedback controls a discharge amount of a high-pressure pump in such a manner that a detected fuel pressure is consistent with a target fuel pressure. The ECU determines whether engine shut sown is imminent. When the ECU determines that engine shut sown is imminent, the target fuel pressure is established lower than a normal fuel pressure. Since the engine is shut down in a condition where the fuel pressure is decreased, a fuel leakage from a fuel injector is unlikely.

Claims

1. A controller for a direct injection engine, the direct injection engine having a high-pressure pump pressurizing a fuel which is directly injected into a cylinder through a fuel injector at a normal fuel pressure for engine idling, the controller comprising:

a pressure detecting device for detecting a fuel pressure which is supplied to the fuel injector;

a target fuel pressure establishing device for establishing a target fuel pressure according to a driving condition of the engine;

a fuel pressure controlling device for controlling a discharge amount of the high-pressure pump in such a manner that the detected fuel pressure is consistent with the target fuel pressure; and

a stop determining device for determining whether engine shut down is imminent, wherein

the target fuel pressure establishing device establishes the target fuel pressure lower than the normal fuel pressure when the stop determining device determines that engine shut down is imminent.

2. A controller according to claim 1, further comprising:

a coolant temperature detecting device for detecting a temperature of an engine coolant, wherein

as the temperature of the engine coolant decreases, the target fuel pressure establishing device increases the target fuel pressure in a range where the target fuel pressure is lower than the normal fuel pressure.

3. A controller according to claim 1, wherein

the stop determining device determines whether engine shut down is imminent based on at least one of an idle command, a position of a shift lever, and a vehicle speed.

4. A controller according to claim 1, further comprising:

an injection mode switching device for switching an injection mode between a single injection mode in which the fuel is injected once during one cycle of a combustion and a divided injection mode in which the fuel is injected a plurality of times during one cycle of the combustion, wherein

the injection mode switching device switches the injection mode from the single injection mode to the divided injection mode when the stop determining device determines that engine shut down is imminent.

5. A controller according to claim 1, further comprising:

a combustion mode switching device for switching a combustion mode between a stratified combustion mode in which the fuel is injected during a intake stroke and a homogeneous combustion mode in which the fuel is injected during a compression stroke, wherein

the combustion mode switching device switches the combustion mode from the stratified combustion mode to the homogeneous combustion when the stop determining device determines that engine shut down is imminent.

6. A controller according to claim 1, further comprising:

a relay device for continuing a fuel injection and an ignition until the detected fuel pressure is decreased to the target fuel pressure after an ignition switch is turned off.

7. A controller for a direct injection engine, the direct injection engine having a high-pressure pump pressurizing a fuel which is directly injected into a cylinder through a fuel injector at a normal fuel pressure for engine idling, the controller comprising:

a pressure detecting means for detecting a fuel pressure which is supplied to the fuel injector;

a target fuel pressure means for establishing a target fuel pressure according to a driving condition of the engine;

a fuel pressure controlling means for controlling a discharge amount of the high-pressure pump in such a manner that the detected fuel pressure is consistent with the target fuel pressure; and

a stop means for determining whether engine shut down is imminent, wherein

the target fuel pressure means establishes the target fuel pressure lower than the normal fuel pressure when the stop means determines that the engine shut down is imminent.

8. A controlling method for a direct injection engine, the direct injection engine having a high-pressure pump pressurizing a fuel which is directly injected into a cylinder through a fuel injector at a normal fuel pressure for engine idling, the controlling method comprising:

detecting a fuel pressure representing a pressure of the fuel which is supplied to the fuel injector;

establishing a target fuel pressure according to a driving condition of the engine;

controlling a discharge amount of the high-pressure pump in such a manner that the detected fuel pressure is consistent with the target fuel pressure; and

determining whether engine is shut down is imminent;

wherein

the target fuel pressure is established lower than the normal fuel pressure when it is determined that engine shut down is imminent.