Operation of a fuel injector having a hydraulic stop

Patent metadata

Field	Value
Publication number	US-11028795-B2
Application number	US-201716339231-A
Country	US
Kind code	B2
Filing date	Sep 28, 2017
Priority date	Oct 12, 2016
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

Various embodiments include a method for operating a fuel injector comprising: applying a first current to a solenoid to perform a first injection process and inject a predefined injection quantity; determining a value of a system parameter indicating the relationship between the actual fuel quantity and the predefined quantity; determining, on the basis of the value of the system parameter, whether the actually injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and an opposite hydraulic force exerted on the armature by fuel; and if it was determined that the quantities differ by enough, applying a second current to the solenoid to perform a second injection; wherein the second current exerts a lower magnetic force on the armature in the direction of the pole piece.

First claim

What is claimed is:

1. A method for operating a fuel injector having a hydraulic stop, a solenoid drive, and a pole piece, wherein the solenoid drive has a movable armature and a nozzle needle moved by the armature, the method comprising:
applying a first current profile to the solenoid drive to perform a first injection process by moving the armature toward the pole piece to the hydraulic stop and inject a predefined injection quantity through a gap between the movable armature and the pole piece into a cylinder of an internal combustion engine;
determining a first value of a system parameter indicative of a relationship between an actual injected fuel quantity and the predefined fuel quantity, wherein the system parameter measures an operational variable of the cylinder;
determining, on the basis of the determined first value of the system parameter, whether the actual injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and the hydraulic stop caused by an opposite hydraulic force exerted on the armature by fuel; and
if it was determined that the quantities differ by the predefined amount, applying a second current profile to the solenoid drive to perform a second injection process into the cylinder;
wherein the second current profile, in comparison with the first current profile, exerts a lower magnetic force on the armature in the direction of the pole piece.

2. The method as claimed in claim 1 , wherein the system parameter corresponds to at least one of: a cylinder-specific smooth running, a cylinder-specific lambda measurement, or a cylinder-specific misfire detection.

3. The method as claimed in claim 1 , wherein:
the first current profile has an associated first peak current value;
the second current profile has an associated second peak current value; and
the second peak current value is smaller than the first peak current value.

4. The method as claimed in claim 1 , wherein:
the first current profile has an associated first holding current value;
the second current profile has an associated second holding current value; and
the second holding current value is smaller than the first holding current value.

5. The method as claimed in claim 1 , wherein:
the first current profile is applied by a first voltage pulse;
the second current profile is applied by a second voltage pulse; and
the second voltage pulse has a lower voltage than the first voltage pulse.

6. The method as claimed in claim 1 , further comprising:
determining a second value of the system parameter;
determining, on the basis of the determined second value of the system parameter, whether the actually injected fuel quantity differs from the predefined fuel quantity by a predetermined quantity corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and an opposite hydraulic force exerted on the armature by fuel; and
if the difference exceeds the predetermined quantity, applying a third current profile to the solenoid drive of the fuel injector in order to perform a third injection process;
wherein the third current profile, in comparison with the second current profile, exerts a lower magnetic force on the armature in the direction of the pole piece.

7. The method as claimed in claim 1 , wherein determining whether the actually injected fuel quantity differs from the predefined fuel quantity by a predetermined quantity comprises comparison of the determined value of the system parameter with a reference value.

8. An engine control unit for a vehicle, the control unit comprising:
a processor; and
a memory storing a set of instructions, the set of instructions when loaded and executed by the processor, causing the processor to:
apply a first current profile to a solenoid drive to perform a first injection process by moving the armature toward the pole piece to the hydraulic stop and inject a predefined injection quantity through a gap between the movable armature and the pole piece into a cylinder of an internal combustion engine;
determine a first value of a system parameter indicative of a relationship between an actual injected fuel quantity and the predefined fuel quantity, wherein the system parameter measures an operation variable of the cylinder;
determine, on the basis of the determined first value of the system parameter, whether the actual injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and the hydraulic stop caused by an opposite hydraulic force exerted on the armature by fuel; and
if it was determined that the quantities differ by the predefined amount, apply a second current profile to the solenoid drive to perform a second injection process;
wherein the second current profile, in comparison with the first current profile, exerts a lower magnetic force on the armature in the direction of the pole piece.

9. A computer program comprising a set of instructions stored on a non-transitory computer readable medium, the set of instructions when loaded and executed by a processor, causing the processor to:
apply a first current profile to a solenoid drive to perform a first injection process by moving the armature toward the pole piece to the hydraulic stop and inject a predefined injection quantity through a gap between the movable armature and the pole piece into a cylinder of an internal combustion engine;
determine a first value of a system parameter indicative of a relationship between an actual injected fuel quantity and the predefined fuel quantity, wherein the system parameter measures an operational variable of the cylinder;
determine, on the basis of the determined first value of the system parameter, whether the actual injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and the hydraulic stop caused by an opposite hydraulic force exerted on the armature by fuel; and
if it was determined that the quantities differ by the predefined amount, apply a second current profile to the solenoid drive to perform a second injection process;
wherein the second current profile, in comparison with the first current profile, exerts a lower magnetic force on the armature in the direction of the pole piece.

Assignees

• Cpt Group Gmbh
• Vitesco Tech Gmbh

Inventors

• Stutika Markus
• Rösel Gerd

Classifications

• F02D41/20 Primary

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

• F02D2041/2048

  said control involving a limitation, e.g. applying current or voltage limits · CPC title

• F02D41/221

  relating to the failure of actuators or electrically driven elements · CPC title

• F02D41/247

  Behaviour for small quantities · CPC title

• F02D2200/0602

  Fuel pressure · CPC title