Control device for internal combustion engine

Patent metadata

Field	Value
Publication number	US-9964092-B2
Application number	US-201615243236-A
Country	US
Kind code	B2
Filing date	Aug 22, 2016
Priority date	Sep 1, 2015
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

An ECU outputs an ignition signal and a discharge waveform control signal. An ignition device performs a closing operation of an ignition switching device while the ignition signal is input into the ignition device. The ignition device adjusts a current flowing through a primary coil to a discharge current command value determined based on the discharge waveform control signal, by performing an opening-closing operation of a control switching device in a period in which the discharge waveform control signal is input into the ignition device after an input of the ignition signal into the ignition device is stopped. The ECU sets the discharge current command value that is a command value for a discharge current of a spark plug to a higher value as a rotation speed is higher, and prolongs a duration, in which discharge controller controls the discharge current, as the rotation speed is lower.

First claim

What is claimed is:

1. A control device for an internal combustion engine, the control device configured to control a controlled variable of the internal combustion engine by operating an ignition device including a spark plug provided in a combustion chamber of the internal combustion engine, an ignition coil connected to the spark plug, a discharge control circuit configured to maintain a discharge current after the spark plug starts electric discharge, and a discharge controller configured to control the discharge current by operating the discharge control circuit, the control device comprising:
a determining processor configured to determine, based on a constituent ratio of an air-fuel mixture in the combustion chamber, whether or not an ignitability of the air-fuel mixture in the combustion chamber in a case where discharge current control by the discharge controller is not executed after the spark plug starts electric discharge, is equal to or lower than a prescribed ignitability; and
an execution command processor configured to cause the discharge controller to execute the discharge current control when the determining processor determines that the ignitability is equal to or lower than the prescribed ignitability, wherein
the execution command processor includes a setting processor configured to set a discharge current command value and a current discharge duration, the discharge current command value being a command value for the discharge current control executed by the discharge controller, and the current discharge duration being a period of time during which the discharge controller controls the discharge current,
the setting processor is configured to set the discharge current command value to a higher value when a rotation speed of the internal combustion engine is greater than a high value than when the rotation speed of the internal combustion engine is lower than a low value, and the setting processor is configured to set the current discharge duration to a longer value when the rotation speed of the internal combustion engine is lower than the low value than when the rotation speed of the internal combustion engine is greater than the high value, wherein the high value is greater than the low value.

2. The control device for the internal combustion engine according to claim 1 ,
wherein the setting processor variably sets the discharge current command value and the current discharge duration based on a load on the internal combustion engine in addition to the rotation speed.

3. The control device for the internal combustion engine according to claim 1 , the control device further comprising a correcting processor configured to make a correction of prolonging the current discharge duration set by the setting processor when an air-fuel ratio in the combustion chamber of the internal combustion engine is equal to or higher than a specified value,
wherein the specified value is higher than a stoichiometric air-fuel ratio.

4. The control device for the internal combustion engine according to claim 1 , wherein:
the internal combustion engine includes a recirculation passage that provides communication between an exhaust passage and an intake passage, and a recirculation valve that adjusts a flow passage cross-sectional area of the recirculation passage; and
the control device includes a correcting processor configured to make a correction of prolonging the current discharge duration set by the setting processor when an exhaust gas recirculation ratio is equal to or higher than a specified ratio, the exhaust gas recirculation ratio being a ratio of exhaust gas flowing into the combustion chamber through the recirculation passage with respect to a fluid flowing into the combustion chamber.

5. The control device for the internal combustion engine according to claim 1 , the control device further comprising a correcting processor configured to make a correction of prolonging the current discharge duration set by the setting processor when an ignition timing of the internal combustion engine is advanced by an amount equal to or greater than a prescribed amount with respect to a reference value.

6. The control device for the internal combustion engine according to claim 1 , the control device further comprising a correcting processor configured to make a correction of prolonging the current discharge duration set by the setting processor when at least one of a condition that a temperature in an intake passage of the internal combustion engine is equal to or lower than a prescribed temperature and a condition that a coolant temperature is equal to or lower than a prescribed coolant temperature is satisfied.

7. The control device for the internal combustion engine according to claim 1 , the control device further comprising:
a detecting processor configured to detect reduction in the ignitability of the air-fuel mixture in the combustion chamber; and
a correcting processor configured to make a correction of prolonging the current discharge duration set by the setting processor when the detecting processor detects reduction in the ignitability.

8. The control device for the internal combustion engine according to claim 1 , wherein:
the internal combustion engine includes a recirculation passage that provides communication between an exhaust passage and an intake passage, and a recirculation valve that adjusts a flow passage cross-sectional area of the recirculation passage; and
the determining processor is configured to determine that the ignitability of the air-fuel mixture in the combustion chamber is equal to or lower than the prescribed ignitability when an exhaust gas recirculation ratio is equal to or higher than a prescribed ratio, the exhaust gas recirculation ratio being a ratio of exhaust gas flowing into the combustion chamber through the recirculation passage with respect to a fluid flowing into the combustion chamber.

9. The control device for the internal combustion engine according to claim 1 , wherein the determining processor determines that the ignitability of the air-fuel mixture in the combustion chamber is equal to or lower than the prescribed ignitability when an air-fuel ratio of the air-fuel mixture in the combustion chamber is equal to or higher than a prescribed value.

10. The control device for the internal combustion engine according to claim 1 , wherein:
the ignition device includes an ignition switching device and a control switching device, the ignition switching device configured to open and close a first loop circuit including a primary coil of the ignition coil and a first power source, and the control switching device configured to open and close a second loop circuit including a second power source and the primary coil;
the discharge control circuit includes the control switching device;
the discharge controller is configured to control the discharge current of the spark plug by performing an opening-closing operation of the control switching device after the spark plug discharges electricity due to an electromotive force that is generated in a secondary coil of the ignition coil when the ignition switching device is switched from a closed state to an open state; and
a polarity of a voltage that is applied to the primary coil by the first power source when the first loop circuit is turned into a closed-loop circuit and a polarity of a voltage that is applied to the primary coil by the second power source when the second loop circuit is turned into a closed-loop circuit are opposite to each other.

Assignees

• Toyota Motor Co Ltd
• Toyota Technical Dev Corporation

Inventors

• Nakamura Satoshi
• Yoshida Takashi

Classifications

• F02P3/04

  Layout of circuits · CPC title

• Y02T10/46

  Cross-Sectional Technologies · mapped topic

• F02P3/0876

  the storage capacitor being charged by means of an energy converter (DC-DC converter) or of an intermediate storage inductance · CPC title

• F02P9/007

  by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition · CPC title

• F02P15/10

  having continuous electric sparks · CPC title