Fuel injection control device and fuel injection system

Patent metadata

Field	Value
Publication number	US-10087876-B2
Application number	US-201715681465-A
Country	US
Kind code	B2
Filing date	Aug 21, 2017
Priority date	May 10, 2013
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

A fuel injection control device is adapted for a fuel injection system including an injector and a high-pressure pump that raises pressure of fuel and supplies the fuel to the injector. The fuel injection control device includes a selecting unit for selecting by which one of full lift injection and partial injection to inject fuel, and a pump control unit for controlling operation of the high-pressure pump such that a pressure of fuel supplied to the injector coincides with a target pressure. The selecting unit selects the partial injection when a required injection quantity of fuel is equal to or smaller than a partial maximum injection quantity. A fuel injection system includes the fuel injection control device, the injector, and the high-pressure pump.

First claim

The invention claimed is:

1. A fuel injection control device adapted for a fuel injection system including an injector comprising:
a fixed core that generates electromagnetic attractive force upon energization of a coil; and
a movable core that is attracted to the fixed core and is displaced together with a valving element, the injector configured to open the valving element and to inject fuel through a nozzle hole,
a computer, including a processor and storage memory for storing instructions which upon execution by the processor configure the computer to at least to perform a selection by which one of full lift injection and partial injection to inject fuel, wherein:
by the full lift injection, the valving element starts to be opened, and reaches its full lift position, and then starts to be closed;
by the partial injection, the valving element starts to be opened, but does not reach its full lift position, and then starts to be closed;
a maximum injection quantity of fuel when the partial injection is performed at a maximum value of a target pressure of fuel supplied to the injector that the fuel injection system is capable of taking is referred to as a partial maximum injection quantity of fuel; and
in the selection, the computer selects the partial injection when a required injection quantity of fuel is equal to or smaller than the partial maximum injection quantity.

2. The fuel injection control device according to claim 1 , wherein:
the fuel injection system includes: a high-pressure pump which is a mechanical pump that is driven by rotary torque of an engine;
an amount of improvement in output efficiency of the engine due to a reduction of a spray particle diameter of fuel as a result of the selection of the partial injection is referred to as an output improved amount;
an amount of reduction in the output efficiency of the engine due to an increase of a load of the high-pressure pump as a result of the selection of the partial injection is referred to as a pump loss amount; and
in the selection, the computer selects the partial injection under a condition that the output improved amount is larger than the pump loss amount.

3. The fuel injection control device according to claim 2 , wherein at time of starting of the engine, in the selection, the computer regards the pump loss amount as larger than the output improved amount.

4. The fuel injection control device according to claim 1 , wherein the computer is further configured to:
detect valve-closing timing of the valving element;
calculate an actual injection quantity of fuel by the partial injection based on the valve-closing timing detected when the partial injection is performed and obtain injection data indicating a relationship between a valve-opening command period of the valving element and the actual injection quantity; and
set a period in which to command the injector to open the valving element based on the required injection quantity and the injection data.

5. The fuel injection control device according to claim 1 , wherein:
the injector is configured such that the valving element also starts to open the nozzle hole simultaneously with a start of the displacement of the movable core.

6. The fuel injection control device according to claim 1 , wherein the injector is structured such that a flow passage length of the nozzle hole is smaller than an inlet diameter of the nozzle hole.

7. The fuel injection control device according to claim 1 , wherein when an engine is in idle operation, in the selection, the computer regards the required injection quantity as equal to or smaller than the partial maximum injection quantity.

8. The fuel injection control device according to claim 1 , wherein:
the injector is disposed at a position where the injector injects fuel directly into a combustion chamber of an engine; and
the engine is an ignition-type internal-combustion engine that ignites and combusts fuel by an ignition device of the engine.

9. The fuel injection control device according to claim 1 , wherein:
the fixed core forms a part of a magnetic circuit configured as a passage for a magnetic flux produced upon energization of the coil and that produces electromagnetic force;
the movable core is attracted by the electromagnetic force to be displaced together with the valving element;
the injector further includes a housing that is inserted and attached in an attachment hole formed at a predetermined position of an engine and that accommodates therein the coil;
the housing has a cylindrical shape that forms a part of the magnetic circuit configured as the passage for the magnetic flux produced upon energization of the coil;
a region of the housing that accommodates the coil is referred to as a coil region; and
an outer peripheral surface of at least a part of the coil region is surrounded with an inner peripheral surface of the attachment hole along its whole circumference.

10. A fuel injection system comprising:
the fuel injection control device recited in claim 1 ;
the injector; and
the high-pressure pump.

11. A fuel injection control device adapted for a fuel injection system including an injector that has:
a fixed core that generates electromagnetic attractive force upon energization of a coil; and
a movable core that is attracted to the fixed core and is displaced together with a valving element, the injector configured to open the valving element and to inject fuel through a nozzle hole,
a computer, including a processor and storage mentor for storing instructions which upon execution by the processor configure the computer to at least set a target pressure of fuel supplied to the injector at a value that is 10 MPa or higher when partial injection is performed wherein by the partial injection, the valving element starts to be opened, but does not reach its full lift position, and then starts to be closed.

12. The fuel injection control device according to claim 11 , wherein:
a relationship between the pressure of fuel supplied to the injector and a spray particle diameter of fuel injected through the nozzle hole is expressed by a characteristic line;
a changing point, at which a second order differential value of the characteristic line is maximized, exists on the characteristic line; and
a lower limit pressure is set at a pressure value at the changing point.

13. The fuel injection control device according to claim 11 , wherein the value that is a lower limit pressure or higher is set at a maximum value of the target pressure that the fuel injection system is capable of taking.

14. The fuel injection control device according to claim 11 , wherein:
the fuel injection system includes a high-pressure pump which is a mechanical pump that is driven by rotary torque of an engine;
an amount of improvement in output efficiency of the engine due to a reduction of a spray particle diameter of fuel as a result of the selection of the partial injection is referred to as an output improved amount;
an amount of reduction in the output efficiency of the engine due to an increase of a load of the high-pressure pump as a result of the selection of the partial injection is referred to as a pump loss amount; and
the computer is further configured to select the partial injection under a condition that the output improved amount is larger than the pump loss amount.

15. The fuel injection control device according to claim 14 , wherein at time of starting of the engine, in the selection, the computer regards the pump loss amount as larger than the output improved amount.

16. The fuel injection contro

Assignees

• Denso Corp

Inventors

• Imai Keita
• Nagatomo Hiroaki
• Itoh Eiji

Classifications

• F02M59/102

  Mechanical drive, e.g. tappets or cams (F02M45/063 takes precedence) · CPC title

• F02M61/1846

  Dimensional characteristics of discharge orifices · CPC title

• F02M51/0671

  the armature having an elongated valve body attached thereto · CPC title

• Y02T10/44

  Cross-Sectional Technologies · mapped topic

• F02D2200/0616

  determined by estimation · CPC title