Control device and control method for internal combustion engine

Patent metadata

Field	Value
Publication number	US-10808673-B2
Application number	US-201916238149-A
Country	US
Kind code	B2
Filing date	Jan 2, 2019
Priority date	Apr 27, 2018
Publication date	Oct 20, 2020
Grant date	Oct 20, 2020

Abstract

To provide a control device, of an internal combustion engine, that accurately identifies the combustion state through ion current detection in a wide operation range of the internal combustion engine, without impairing the reliability and the durability of the control device of the internal combustion engine. This internal combustion engine control device includes: an ignition plug having a center electrode and a ground electrode opposed to each other with a gap therebetween; a circulation device for short-circuiting a primary winding to cause a circulation route to enter a conduction state, thereby stopping spark discharge; and an ion-current-detection bias voltage control device for controlling bias voltage for ion current detection. The potential of the center electrode in an ion current detection period is controlled by adjusting the value of the bias voltage and the changing speed of the bias voltage.

First claim

What is claimed is:

1. An internal combustion engine control device comprising:
an ignition plug having a first electrode and a second electrode which are opposed to each other with a gap therebetween, the ignition plug being for igniting a combustible air-fuel mixture in a combustion chamber;
an ignition device including a primary winding supplied with current from a power supply device and a secondary winding magnetically coupled to the primary winding, the ignition device being for supplying ignition energy to the ignition plug;
an ion current detection device having an ion current detection circuit and an ion-current-detection bias voltage control device, the ion current detection circuit being for detecting, as ion current, ion generated in the combustion chamber as a result of the combustible air-fuel mixture being combusted due to spark discharge caused by the ignition energy, the ion-current-detection bias voltage control device being for controlling bias voltage for ion current detection; and
a circulation device for short-circuiting the primary winding to cause a circulation route to enter a conduction state, thereby stopping the spark discharge, wherein
the ion-current-detection bias voltage control device performs control such that: the bias voltage is increased such that a potential of the first electrode becomes a positive voltage during a period in which the spark discharge is stopped by the circulation device and ion current is detected; and the bias voltage is decreased at an end of the period in which the spark discharge is stopped by the circulation device.

2. The internal combustion engine control device according to claim 1 , comprising
a driver circuit having mounted therein a switch for controlling conduction and interruption of current that is supplied from the power supply device to the primary winding, wherein
the ion-current-detection bias voltage control device is built in the driver circuit.

3. The internal combustion engine control device according to claim 1 , wherein
the ion-current-detection bias voltage control device comprises: a parallel circuit composed of a capacitor and a Zener diode; and a short circuit for short-circuiting both ends of the Zener diode.

4. The internal combustion engine control device according to claim 3 , wherein
the short circuit comprises a series circuit composed of a resistor and a switch.

5. The internal combustion engine control device according to claim 3 , wherein
in an ignition cycle in which the spark discharge stop by the circulation device is not performed among the plurality of ignition cycles, an internal resistance value of the short circuit is 2 kΩ or less.

6. The internal combustion engine control device according to claim 3 , wherein
the short circuit is configured such that, when the bias voltage is switched to a lower voltage level outside the period in which ion current is detected, an internal resistance value of the short circuit is not less than 20Ω.

7. The internal combustion engine control device according to claim 6 , wherein
the short circuit is configured such that, during the period in which ion current is detected, the internal resistance value of the short circuit is in a range of 50 kΩ to 500 kΩ.

8. The internal combustion engine control device according to claim 3 , wherein
the ion-current-detection bias voltage control device comprises: a plurality of the Zener diodes which are connected in series to each other and which are connected in parallel to the capacitor; and the short circuits which are respectively provided for the plurality of the Zener diodes and which each short-circuit both ends of a corresponding one of the Zener diodes.

9. The internal combustion engine control device according to claim 8 , wherein
each short circuit comprises a series circuit composed of a resistor and a switch.

10. The internal combustion engine control device according to claim 8 , wherein
the ion-current-detection bias voltage control device controls the bias voltage such that the potential of the first electrode becomes a constant positive voltage during the period in which the spark discharge is stopped by the circulation device and ion current is detected.

11. The internal combustion engine control device according to claim 10 , wherein
the ion-current-detection bias voltage control device controls a decreasing speed of the bias voltage by use of internal resistance of each short circuit such that the potential of the first electrode becomes a constant positive voltage during the period in which the spark discharge is stopped by the circulation device and ion current is detected.

12. The internal combustion engine control device according to claim 11 , wherein
each short circuit is composed of a plurality of sets of a resistor and a switch which are connected in series to each other, the plurality of sets being connected in parallel to each other, and
an internal resistance value of the short circuit is adjusted through combination of conduction states of the plurality of the switches.

13. The internal combustion engine control device according to claim 3 , wherein
the ion-current-detection bias voltage control device controls the bias voltage such that the potential of the first electrode becomes a constant positive voltage during the period in which the spark discharge is stopped by the circulation device and ion current is detected.

14. The internal combustion engine control device according to claim 13 , wherein
the ion-current-detection bias voltage control device controls a decreasing speed of the bias voltage by use of internal resistance of the short circuit such that the potential of the first electrode becomes a constant positive voltage during the period in which the spark discharge is stopped by the circulation device and ion current is detected.

15. The internal combustion engine control device according to claim 14 , wherein
the short circuit is composed of a plurality of sets of a resistor and a switch which are connected in series to each other, the plurality of sets being connected in parallel to each other, and
an internal resistance value of the short circuit is adjusted through combination of conduction states of the plurality of the switches.

16. The internal combustion engine control device according to claim 14 , wherein
a time point at which the ion-current-detection bias voltage control device starts the control of the decreasing speed of the bias voltage such that the potential of the first electrode becomes a constant positive voltage is calculated from information of ion current surge that occurs when the spark discharge is stopped.

17. The internal combustion engine control device according to claim 14 , wherein
a target value of the decreasing speed of the bias voltage controlled by the ion-current-detection bias voltage control device is calculated from information of voltage across both ends of the primary winding or information of circulation current of the primary winding while the spark discharge is stopped, and the target value is determined for each ignition cycle.

18. A method for controlling an internal combustion engine including:
an ignition plug having a first electrode and a second electrode which are opposed to each other with a gap therebetween, the ignition plug being for igniting a combustible air-fuel mixture in a combustion chamber;
an ignition device including a primary winding supplied with current from a power supply device and a secondary winding magnetically coupled to the primary wi

Assignees

• Mitsubishi Electric Corp

Inventors

• Nakamura Toshifumi
• Inada Takahiko

Classifications

• F02D35/021 Primary

  using an ionic current sensor · CPC title

• F02P17/12 Primary

  Testing characteristics of the spark, ignition voltage or current (testing of sparking plugs H01T13/60) · CPC title

• F02D35/027

  using knock sensors · CPC title

• F02P2017/128

  for knock detection · CPC title

• G01L23/225

  circuit arrangements therefor · CPC title