Ion current detection apparatus for an internal combustion engine

• US 6,075,366 A
• Filed: 05/01/1998
• Issued: 06/13/2000
• Est. Priority Date: 11/26/1997
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Yasuda, Yukio
• Primary Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US09/070,723
• Time in Patent Office: 774 Days
• Field of Search: 324/380, 324/382, 324/388, 324/464, 73/35.08, 73/116, 73/117.2, 73/117.3
• US Class Current: 324/380
• CPC Class Codes: F02P 17/12 Testing characteristics of the spark, ignition voltage or current testing of sparking plugs H01T13/60
• CPC Class Codes: F02P 2017/125 Measuring ionisation of combustion gas, e.g. by using ignition circuits
• CPC Class Codes: F02P 3/093 Closing the discharge circuit of the storage capacitor with semiconductor devices

Abstract

An ion current detection apparatus for an internal combustion engine includes a voltage limiting device for limiting an amount of counterelectromotive force of a primary coil of ignition coil applied to switching elements, a capacitor for applying an ion current detection voltage to a spark plug, and an ion current detection circuit for detecting an ion current wherein the capacitor is connected to the voltage limiting device.

Claims

1. An ion current detection apparatus for detecting an ion current occurring during combustion in an internal combustion engine, wherein said internal combustion engine comprises an ignition coil for generating a high voltage charge on a secondary coil thereof by means of a voltage applied to a primary coil thereof, and a spark plug for igniting fuel inside an engine cylinder as a result of the high voltage generated in the ignition coil, said ion current detection apparatus comprising:

a voltage limiting device isolated from said secondary coil and adapted to limit an amount of a counterelectromotive force of said primary coil applied to a switching element used for controlling a current supply to the primary coil;

a capacitor for applying an ion current detection voltage to the spark plug via the secondary coil;

an ion current detection means for detecting an ion current based on a voltage applied from said capacitor to the spark plug; and

a connecting means for connecting said capacitor to the voltage limiting device;

wherein the voltage limiting device is used for capacitor voltage limiting.

2. The ion current detection apparatus for an internal combustion engine according to claim 1, wherein:

said capacitor is charged by current flowing during sparking of said spark plug, and said capacitor discharges the stored voltage charge to said spark plug immediately after sparking is completed, and

said voltage limiting device limits a voltage supplied to said capacitor during capacitor charging.

3. The ion current detection apparatus for an internal combustion engine according to claim 1, wherein:

said connecting means comprises a first diode configured to connect said primary coil and said switching element, and a second diode configured to connect said capacitor and said voltage limiting device.

4. The ion current detection apparatus for an internal combustion engine according to claim 1, wherein:

said voltage limiting device is a zener diode.

5. An ion current detection apparatus for detecting an ion current occurring during combustion in an internal combustion engine, wherein said internal combustion engine comprises an ignition coil for generating a high voltage charge on a secondary coil thereof by means of a voltage applied to a primary coil thereof, and a spark plug for igniting fuel inside an engine cylinder as a result of the high voltage generated in the ignition coil, said ion current detection apparatus comprising:

a voltage limiting means isolated from said secondary coil and adapted to limit an amount of a counterelectromotive force of said primary coil applied to a switching element used for controlling current supply to the primary coil;

a capacitor for applying an ion current detection voltage to the spark plug via the secondary coil;

an ion current detection means for detecting an ion current based on a voltage applied from said capacitor to the spark plug; and

a connecting means for connecting said capacitor to the voltage limiting means;

wherein the voltage limiting means is used for capacitor voltage limiting.

6. The ion current detection apparatus for an internal combustion engine according to claim 5, wherein:

said capacitor is charged by current flowing during sparking of said spark plug, and said capacitor discharges the stored voltage charge to said spark plug immediately after sparking is completed, and

said voltage limiting means limits a voltage supplied to said capacitor during capacitor charging.

7. The ion current detection apparatus for an internal combustion engine according to claim 5, wherein:

said connecting means comprises a first diode configured to connect said primary coil and said switching element, and a second diode configured to connect said capacitor and said voltage limiting device.

8. An ion current detection apparatus for detecting an ion current occurring during combustion in an internal combustion engine, wherein said internal combustion engine comprises an ignition coil for generating a high voltage charge on a secondary coil thereof by means of a voltage applied to a primary coil thereof, and a spark plug for igniting fuel inside an engine cylinder as a result of the high voltage generated in the ignition coil, said ion current detection apparatus comprising:

a zener diode adapted to limit an amount of a counterelectromotive force of said primary coil applied to a switching element used for controlling a current supply to the primary coil;

a capacitor configured to apply an ion current detection voltage to the spark plug via the secondary coil and being connected to said zener diode;

an ion current detector configured to detect an ion current based on a voltage applied from said capacitor to the spark plug; and

wherein the zener diode is used for capacitor voltage limiting.

9. The ion current detection apparatus for an internal combustion engine according to claim 8, wherein:

said capacitor is charged by current flowing during sparking of said spark plug, and said capacitor discharges the stored voltage charge to said spark plug immediately after sparking is completed, and

said zener diode limits a voltage supplied to said capacitor during capacitor charging.

10. The ion current detection apparatus for an internal combustion engine according to claim 8, wherein:

said capacitor is connected to said zener diode by a first diode configured to connect said primary coil and said switching element, and a second diode configured to connect said capacitor and said zener diode.