Fuel injection controller and fuel injection system

Patent metadata

Field	Value
Publication number	US-10087870-B2
Application number	US-201314071200-A
Country	US
Kind code	B2
Filing date	Nov 4, 2013
Priority date	Nov 5, 2012
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

A fuel injection controller is applied to a fuel injector injecting fuel to be combusted in an internal combustion engine by an open-valve operation of the valve body according to an electromagnetic suction force generated by an energization of a coil. The fuel injection controller controls an injection state of the fuel injector by controlling a coil current flowing through the coil. The fuel injection controller includes an increasing control portion which increases the coil current to a first target value, a holding control portion which holds the coil current increased by the increasing control portion to the first target value, and a changing portion which changes the first target value according to the operation state of the internal combustion engine.

First claim

What is claimed is:

1. A fuel injection controller for a fuel injector injecting fuel to be combusted in an internal combustion engine by an open-valve operation of the valve body according to an electromagnetic suction force generated by an energization of a coil, the fuel injection controller controlling an injection state of the fuel injector by controlling a coil current flowing through the coil, the fuel injection controller comprising:
an increasing control portion applying a boost voltage that is obtained by boosting the battery voltage to the coil to increase an average of the coil current to a first target value;
a first holding control portion applying the boost voltage to the coil to hold the average of the coil current increased by the increasing control portion to the first target value;
a second holding control portion applying the battery voltage to the coil to hold the average of the coil current to a second target value or a third target value; and
a changing portion changing the first target value according to an operation state of the internal combustion engine, wherein
target values of the average of the coil current includes the first target value, the second target value and the third target value, the second target value is less than the first target value, the third target value is less than the second target value,
the increasing control portion and the first holding control portion controls the boost voltage applied to the coil to start to open the valve body in a time period where the average of the coil current is held to the first target value,
the second holding control portion controls the battery voltage applied to the coil in a time period where the average of the coil current is held to the second target value before the open-valve operation is completed, and
the second holding control portion controls the battery voltage applied to the coil in a time period where the average of the coil current is held to the third target value after the open-valve operation is completed.

2. A fuel injection controller according to claim 1 , wherein
the changing portion sets the first target value of when the internal combustion engine is running at an idle operation state to a value less than the first target value of when the internal combustion engine is running at other operation states.

3. A fuel injection controller according to claim 1 , wherein
the changing portion sets the first target value of when an injection amount generated by opening and closing the valve body for once is at a small injection state in which the injection amount is less than a predetermined amount to a value less than the first target value of when the injection amount is greater than or equal to the predetermined amount.

4. A fuel injection controller according to claim 1 , wherein
the changing portion sets the first target value of when an injection allow period allowable for injecting fuel in a single combustion cycle of the internal combustion engine is less than a predetermined time period to a value greater than the first target value of when the injection allow period is greater than or equal to the predetermined time period.

5. A fuel injection controller according to claim 1 , wherein
the changing portion sets the first target value of an operation state where a temperature of a circuit controlling the coil current is greater than or equal to a predetermined temperature is set to a value less than the first target value of an operation state where the temperature of the circuit is less than the predetermined temperature.

6. A fuel injection controller according to claim 1 , wherein
the electromagnetic suction force required for starting to open the valve body is referred to as a required opening force,
the electromagnetic suction force saturated by holding the average of the coil current to the first target value is referred to as a static suction force, and
the first target value is set to a value so that the static suction force is greater than or equal to the required opening force.

7. A fuel injection controller according to claim 1 , further comprising:
a boost circuit boosting the battery voltage to the boost voltage; and
a battery holding control portion applying the battery voltage to the coil to hold the average of the coil current to a second target value after the second holding control portion is executed, wherein
the increasing control portion and the first holding control portion applies the boost voltage boosted by the boost circuit to the coil, and
the second target value is set to a value where the electromagnetic suction force which is increased by the increasing control portion and the second holding control portion can be held.

8. A fuel injection system comprising:
a fuel injection controller according to claim 1 ; and
the fuel injector.

9. A fuel injection controller according to claim 1 , wherein
the first holding control portion performs holding control by controlling a duty ratio of the boost voltage applied to the coil to hold the average of the coil current so that the valve body is started to be opened in the holding control.

10. A fuel injection controller according to claim 1 , wherein
the valve body is not opened when the increasing control portion applies the boost voltage to the coil to increase the average of the coil current to the first target value.

11. A fuel injection controller for a fuel injector injecting fuel to be combusted in an internal combustion engine by an open-valve operation of the valve body according to an electromagnetic suction force generated by an energization of a coil, the fuel injection controller controlling an injection state of the fuel injector by controlling a coil current flowing through the coil, the fuel injection controller comprising:
a computer, including a processor and a memory, the computer being configured to at least perform:
an increasing control including applying a boost voltage that is obtained by boosting a battery voltage to the coil to increase an average of the coil current to a first target value;
a first holding control including applying the boost voltage to the coil to hold the average of the coil current increased by the increasing control to the first target value;
a second holding control applying the battery voltage to the coil to hold the average of the coil current to a second target value or a third target value; and
a changing control including changing the first target value according to an operation state of the internal combustion engine; wherein

target values of the average of the coil current includes the first target value, the second target value and the third target value, the second target value is less than the first target value, the third target value is less than the second target value;
the increasing control and the holding control controls the boost voltage applied to the coil to start to open the valve body in a time period where the average of the coil current is held to the first target value; and
the second holding control controls the battery voltage applied to the coil in a time period where the average of the coil current is held to the second target value before the open-valve operation is completed, and
the second holding control controls the battery voltage applied to the coil in a time period where the average of the coil current is held to the third target value after the open-valve operation is completed.

12. A fuel injection controller according to claim 11 , wherein
the changing control sets the first target value of when the internal combustion engine is running at an idle operation state to a value

Assignees

• Denso Corp

Inventors

• Imai Keita
• Ito Eiji

Classifications

• F02D2041/2058

  using information of the actual current value · CPC title

• F02D41/30 Primary

  Controlling fuel injection {(F02D41/182, F02D41/24 take precedence)} · CPC title

• F02D41/08

  for idling (F02D41/06, F02D41/16 take precedence) · CPC title

• F02D41/20 Primary

  Output circuits, e.g. for controlling currents in command coils · CPC title

• F02D2041/2006

  by using a boost capacitor · CPC title