Control device and control method of engine

Patent metadata

Field	Value
Publication number	US-10012160-B2
Application number	US-201414760930-A
Country	US
Kind code	B2
Filing date	Jan 10, 2014
Priority date	Jan 18, 2013
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

It is possible to prevent the stability of an engine from deteriorating even when degrees of changes over time of injection characteristics are different in each fuel injection valve. An inter-cylinder air-fuel ratio variation detection unit 1100 calculates an air-fuel ratio variation index (Ind_imb) which indicates a degree of variation in an air-fuel ratio between cylinders from an exhaust air-fuel ratio, engine rotation speed, or the like. Unlike in a case where the air-fuel ratio variation index (Ind_imb) is lower than a set value, when the air-fuel ratio variation index (Ind_imb) is higher than the set value, a fuel injection pulse width limitation unit 2100 sets a (allowable) minimum value (Min_TI) of a fuel injection pulse width so as to be greater. In addition, a fuel injection pulse width calculation unit 3100 calculates fuel injection pulse widths (TI_1, TI_2, TI_3, and TI_4) of cylinders so as not to be lower than the minimum value (Min_TI).

First claim

The invention claimed is:

1. An apparatus for an engine, the apparatus comprising:
a control device that is configured to control the engine, the engine being a multi-cylinder engine in which a fuel injection valve is provided in each of a plurality of cylinders, wherein
the control device is configured to control the fuel injection valve such that a minimum value of an injection pulse width of the fuel injection valve is limited to be more than a predetermined value when variation in an air-fuel ratio between the plurality of cylinders is detected during operation of the multi-cylinder engine, and
the control device is further configured to detect a static flow characteristic change and a dynamic flow characteristic change of the fuel injection valve of each cylinder based on the air-fuel ratio of each cylinder, and the predetermined value is changed based on the static flow characteristic change and the dynamic flow characteristic change of the fuel injection valve of each cylinder.

2. The apparatus according to claim 1 , wherein the control device is further configured to detect the variation in the air-fuel ratio when the injection pulse width is greater than a first predetermined value, and the injection pulse width is limited so as to be greater than a second predetermined value (first predetermined value>second predetermined value) when the variation in the air-fuel ratio is greater than a set value.

3. The apparatus according to claim 2 , wherein the control device is further configured to detect amplitude during a two-rotation period of an engine in an exhaust air-fuel ratio of an exhaust pipe collection portion.

4. The apparatus according to claim 2 , wherein the control device is further configured to detect a variation in a rotation change in each cylinder as the index value of the variation in the air-fuel ratio.

5. The apparatus according to claim 2 , wherein the control device is further configured to detect a width of the variation in the air-fuel ratio in each cylinder.

6. The apparatus according to claim 1 , wherein the control device is further configured to detect the static flow characteristic change and the dynamic flow characteristic change of the fuel injection valve of each cylinder based on the air-fuel ratio of each cylinder in each of the injection pulse widths which are different from each other.

7. The apparatus according to claim 6 , wherein the control device is further configured to detect an allowable pulse width of each cylinder based on the static flow characteristic change and the dynamic flow characteristic change of the fuel injection valve of each cylinder, and the control device sets the predetermined value based on the allowable pulse width of each cylinder.

8. The apparatus according to claim 7 , wherein when the injection pulse width is less than the predetermined value according to an operational state of the engine, the control device is further configured to limit injection pulse width to be greater than the predetermined value by changing the injection pulse width to the predetermined value.

9. The apparatus according to claim 7 , wherein when the injection pulse width in each fuel injection is less than the predetermined value in a multi-stage injection in which fuel injection is performed multiple times during one cycle, the control device is further configured to limit the injection pulse width to be greater than the predetermined value by decreasing the number of times of performing the injection in the multi-stage injection or inhibiting the multi-stage injection.

10. The apparatus according to claim 7 , wherein when the injection pulse width during an idle operation of the engine is less than the predetermined value, the control device is further configured to limit the injection pulse width to be greater than the predetermined value by increasing engine rotation speed during an idle operation.

11. The apparatus according to claim 10 , wherein the predetermined value is a value which makes the air-fuel ratio of each cylinder be within a flammable air-fuel ratio range.

12. A method for controlling an engine, the method comprising:
controlling a fuel injection valve of the engine, with a control device, such that a minimum value of an injection pulse width of the fuel injection valve is limited to be more than a predetermined value when variation in an air-fuel ratio between a plurality of cylinders of the engine is detected during operation of the engine, and
detecting, with the control device, a static flow characteristic change and a dynamic flow characteristic change of the fuel injection valve of each cylinder based on the air-fuel ratio of each cylinder, and the predetermined value is changed based on the static flow characteristic change and the dynamic flow characteristic change of the fuel injection valve of each cylinder.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Nakagawa Shinji
• Numata Akihito
• Fukuchi Eisaku

Classifications

• F02D41/0085 Primary

  Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio · CPC title

• F02D41/247

  Behaviour for small quantities · CPC title

• F02D41/40

  with means for controlling injection timing or duration · CPC title

• F02D41/1456

  with sensor output signal being linear or quasi-linear with the concentration of oxygen · CPC title

• F02D41/1498

  measuring engine roughness · CPC title