Ignition apparatus of internal combustion engine

• US 10,641,230 B2
• Filed: 01/10/2019
• Issued: 05/05/2020
• Est. Priority Date: 01/11/2018
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Wakasugi, Ryota, Sugiura, Akimitsu
• Primary Examiner(s): Vilakazi, Sizo B
• Assistant Examiner(s): Kirby, Brian R
• Application Number:
  US16/244,382
• Publication Number:
  US 20190211793A1
• Time in Patent Office: Days
• CPC Class Codes: F02P 3/01 Electric spark ignition installations without subsequent energy storage, i.e. energy supplied by an electrical oscillator with magneto- or dynamo-electric generators F02P1/00; piezoelectric ignition F02P3/12; with continuous electric spark F02P15/10
• CPC Class Codes: F02P 3/0407 Opening or closing the primary coil circuit with electronic switching means F02P3/045 - F02P3/055 take precedence
• CPC Class Codes: F02P 9/002 Control of spark intensity, intensifying, lengthening, suppression by means of current control in the storage devices F02P3/05, F02P3/09, during starting F02P15/12
• CPC Class Codes: F02P 9/007 by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition

Abstract

An ignition apparatus of an internal combustion engine is provided with an ignition plug, an AC (alternating current) voltage application unit configured to apply AC voltage to the center electrode of the ignition plug, and an application voltage control unit that controls an operation of the AC voltage application unit. The application voltage control unit is configured to control the AC voltage application unit to apply the center electrode with a first AC voltage having an amplitude smaller than that of a required voltage of the ignition plug in a first period which is before an ignition timing, and to apply the center electrode with a second AC voltage having an amplitude smaller than that of the first AC voltage or to stop applying the center electrode with the AC voltage during a second period which is before the ignition timing after the first period has elapsed.

Claims

1. An ignition apparatus of an internal combustion engine comprising:

an ignition plug including;

an insulator having a cylindrical shape,

a center electrode having a rod-shape, being supported in the insulator to be coaxial therewith, in which a tip end of the center electrode is exposed therefrom,

a housing that supports the insulator,

a ground electrode connected to the housing, forming a discharge gap between the tip end of the center electrode and the ground electrode, and

a pocket constituted of a space formed between an outer periphery surface of a tip end of the insulator and an inner periphery surface of the housing, in which a portion in a tip end side of the pocket is opened;

an AC (alternating current) voltage application unit configured to apply AC voltage to the center electrode; and

an application voltage control unit that controls an operation of the AC voltage application unit,

wherein

the application voltage control unit is configured to control the AC voltage application unit to apply the center electrode with a first AC voltage having an amplitude which is smaller than that of a required voltage of the ignition plug in a first period which is before an ignition timing, and to apply the center electrode with a second AC voltage having an amplitude smaller than that of the first AC voltage or to stop applying the center electrode with the AC voltage during a second period which is before the ignition timing after the first period has elapsed.

2. The ignition apparatus according to claim 1, wherein

the first period is included in a period from a start of an intake stroke to an end of a compression stroke.

3. The ignition apparatus according to claim 1, wherein

the first period is defined as a period extending from an intake stroke to a compression stroke in the internal combustion engine.

4. The ignition apparatus according to claim 1, wherein

the apparatus includes an internal cylinder pressure estimation unit that estimates internal cylinder pressure of the internal combustion engine;

and

the application voltage control unit is configured to control an amplitude of the first AC voltage to be lower than a predetermined reference amplitude when an estimated internal cylinder pressure estimated by the internal cylinder pressure estimation unit is lower than a predetermined reference value, and to control the amplitude of the first AC voltage to be higher than the predetermined reference amplitude when the estimated internal cylinder pressure is higher than the predetermined reference value.

5. The ignition apparatus according to claim 1, wherein

the apparatus includes an internal cylinder pressure detection unit configured to detect internal cylinder pressure of the internal combustion engine;

and

the application voltage control unit is configured to control an amplitude of the first AC voltage to be lower than a predetermined reference amplitude when a detected internal cylinder pressure detected by the internal cylinder pressure detection unit is lower than a predetermined reference value, and to control the amplitude of the first AC voltage to be higher than the predetermined reference amplitude when the detected internal cylinder pressure is higher than the predetermined reference value.

6. The ignition apparatus according to claim 1, wherein

the apparatus includes a rotation speed detection unit that detects an engine rotation speed of the internal combustion engine;

and

the application voltage control unit is configured to set a duration of the second period to be longer than a predetermined reference period when the engine rotation speed detected by the rotation speed detection unit is higher than a predetermined reference value, and to set the duration of the second period to be shorter than the predetermined reference period when the engine rotation speed is lower than the predetermined reference value.

7. The ignition apparatus according to claim 1, wherein

the apparatus includes a power source voltage detection unit that detects an output voltage of a power source that supplies power to the AC voltage application unit;

and

the application voltage control unit is configured such that an ON period of an application signal used for applying the first AC voltage is capable of being adjusted based on the output voltage detected by the power source voltage detection unit.

8. The ignition apparatus according to claim 1, wherein

the application voltage control unit is configured to set a duration of the second period to be a period where ionized gaseous molecules which are generated in the pocket reach the discharge gap.

9. The ignition apparatus according to claim 1, wherein

the application voltage control unit is configured to set a duration t2 of the second period to satisfy a relationship d1/v2<

T2<

d/v1+d2/v2, where the shortest linear distance between the pocket and the discharge gap is d1, the longest linear distance between the pocket and the discharge gap is d2, a depth in an axial direction of the pocket is d, a diffusion speed in the pocket is v1, and a flow rate at the discharge gap in the pocket is v2.