JP4968203B2 - Plasma ignition device - Google Patents

Description

  The present invention relates to improvement of ignition stability of a plasma ignition device used for ignition of an internal combustion engine.

In recent years, in an internal combustion engine such as an automobile, further improvement in fuel consumption and dilution have been desired in order to reduce environmental load substances such as nitrogen oxides and carbon dioxide contained in combustion exhaust. A lean combustion engine such as stratified lean combustion or homogeneous lean combustion can be expected to have higher output and lower fuel consumption, but its ignitability is reduced. For this reason, ignition plugs used for ignition of these inflammable engines are required to have high ignitability.
As an ignition device with high ignitability used for such an inflammable engine, a plasma ignition device is expected. The plasma ignition device applies a high voltage and a large current in a discharge space partitioned inside the insulator by a center electrode and a ground electrode of the spark plug and a substantially cylindrical insulator that insulates between them. The gas in the discharge space is made into a high-temperature and high-pressure plasma state by injecting high energy into the combustion chamber of the internal combustion engine to ignite the non-ignitable air-fuel mixture. (For example, refer patent document 1 etc.).
Japanese Utility Model Publication No. 55-051827

  However, in such a plasma ignition device, deposits are deposited on the inner peripheral wall of the cylindrical insulator forming the discharge space due to incomplete combustion of the air-fuel mixture, or the metal of the electrode evaporated by sputtering during discharge. There is a risk that the components may be vapor deposited to cause channeling to form a conduction path. When a high voltage is applied, deposits such as deposits and channeling become resistance components, and the center electrode and the ground electrode are short-circuited through these deposits, so a discharge path is not formed in the discharge space. It has been found that a large current may not flow into the discharge space.

Therefore, in view of such circumstances, the present invention supplies high energy into the discharge space partitioned inside the insulator that insulates the center electrode and the ground electrode, and changes the gas in the discharge space to a high-temperature and high-pressure plasma state. In a plasma ignition device that injects and ignites an internal combustion engine, even if deposits are formed on the peripheral surface of the insulator forming a discharge space, stable ignition is achieved and unnecessary trigger discharge is performed. An object of the present invention is to provide a plasma ignition device that can avoid excessive electrode consumption .

According to the first aspect of the present invention, an ignition plug having a discharge space partitioned by a center electrode, a ground electrode, and an insulator that insulates them, and a high energy power source for supplying high energy to the ignition plug is used as a single ignition. A plurality of trigger power sources that perform a plurality of trigger discharges each time, and a plasma energy power source that supplies a large current into the discharge space that is broken down by the trigger discharge, and the gas in the discharge space is A plasma ignition device that ignites an air-fuel mixture of an internal combustion engine by applying high energy from an energy power source to form a high-temperature / high-pressure plasma state, wherein the multiple-time trigger power source includes a plurality of trigger discharge circuits, The trigger discharge circuit comprises a capacitor as energy storage means for storing the power supply voltage, and boosting means for boosting the discharge voltage from the energy storage means; Comprising a coil Te, each of the trigger discharge circuit, allowed connected in parallel with the spark plug, the multiple trigger discharge, it performs the ignition process to TDC from BTDC 30 °, the trigger discharge emanating the repetition The discharge interval is within 20 μs .

According to a second aspect of the present invention, the multi-time trigger power source is composed of a plurality of trigger discharge circuits corresponding to the number of triggers, and each of the trigger discharge circuits accumulates a power source voltage and generates energy at a high voltage. A piezoelectric transformer is provided as means, and each trigger discharge circuit is connected in parallel to the spark plug, and the trigger discharge is performed in the ignition process from BTDC 30 ° to TDC, and the trigger is repeatedly generated. It is good also as a structure characterized by the discharge interval of discharge being less than 20 microseconds .

According to a third aspect of the present invention, the multi-time trigger power supply includes an electronic control device that generates an ignition signal in accordance with an operating condition of the internal combustion engine, and a multi-time trigger signal in response to the ignition signal. A trigger discharge circuit selection control device that selectively controls any one of the plurality of trigger discharge circuits may be provided.

According to a fourth aspect of the present invention, the multiple-time trigger power supply includes a discharge delay means for delaying a discharge from the energy storage means, and the discharge delay means causes a plurality of discharges from the boosting means. Alternatively, a time difference may be provided.

  Further, according to a fifth aspect of the present invention, the multiple-time trigger power supply includes plasma current detection means for detecting a large current flowing from the plasma power supply, and the trigger discharge is detected when the plasma current is detected. It is desirable to stop

According to a sixth aspect of the present invention, the spark plug includes a long-axis center electrode, a cylindrical insulating member that covers the outer periphery of the center electrode, and a substantially annular ground electrode that covers the outer periphery of the insulating member. The insulator is extended downward from the lower end surface of the center electrode toward the combustion chamber, the discharge space is formed inside the insulator, and is injected into the combustion chamber of the internal combustion engine from the opening of the ground electrode. It is good also as composition to do. With such a configuration, in a plasma ignition device that ignites an internal combustion engine by injecting a large volume of plasma, a short circuit due to deposits or the like existing on the discharge path is suppressed and reliable ignition is performed. It can be carried out.

Further, according to a seventh aspect of the present invention, the spark plug includes a center electrode, an insulator that covers the center electrode, and an annular ground electrode that covers the insulator, and a lower end surface of the center electrode and the ground electrode The lower end surface of the insulator is disposed so that it is substantially flush with the lower end surface of the center electrode, or the lower end surface of the center electrode protrudes toward the combustion chamber from the lower end surface of the ground electrode. A configuration may be adopted in which an extremely shallow discharge space is formed facing the room, and the outer peripheral surface of the center electrode and the inner peripheral surface of the ground electrode are opposed to the discharge space. Even in such a plasma ignition device using a so-called creeping discharge type ignition plug, a short circuit due to deposits or the like existing on the discharge path can be suppressed and reliable ignition can be performed.

In addition, as in an eighth aspect of the invention, the spark plug includes at least a part of a center electrode, a cylindrical insulator covering the outer periphery of the center electrode, and a substantially annular ground electrode covering the outer periphery of the insulator. It is good also as a structure which extended this to the combustion chamber side lower side of the center electrode, and formed the said discharge space in the combustion chamber. In such plasma spark plugs using so-called spark plug type spark plugs and in plasma ignition devices using so-called creeping discharge spark plugs, short-circuiting due to deposits etc. existing on the discharge path can be achieved. Suppressing and reliable ignition can be performed.

According to the present invention, a high voltage is applied from the multi-time trigger power source to the spark plug in accordance with an ignition signal generated from the electronic control unit in accordance with an operation state of the internal combustion engine, and at a plurality of times with a very short discharge interval within 20 μs. The trigger discharge is performed a plurality of times at an extremely short discharge interval within 20 μs in the discharge space defined in the spark plug.
At this time, deposits formed by incomplete combustion of the air-fuel mixture, etc. on the inner peripheral wall of the insulator forming the discharge space, the lower end surface of the insulator, etc., or electrodes evaporated by sputtering during discharge When deposits of metal components, etc. are attached, if a discharge current flows to the deposits due to the above-mentioned multiple trigger discharges, the deposits will self-heat due to internal resistance and burn out, or re-transpiration by sputtering. Removed by.
Further, even if the deposits are not completely removed by a plurality of trigger discharges, the discharge position may change, whereby the insulation in the discharge space may be broken and an air discharge may occur.

  When a plurality of trigger discharges removes deposits or forms another air discharge path and the insulation in the discharge space is broken, a large current flows from the plasma power source into the discharge space in a very short time. The gas in the discharge space is released into a high-temperature and high-pressure plasma state, and is injected into the combustion chamber as volume plasma having a large volume, so that the air-fuel mixture in the combustion chamber can be ignited.

  On the other hand, if there is no deposit on the inner peripheral wall of the insulator that partitions the discharge space, the insulation in the discharge space is destroyed when the first trigger discharge from the multiple trigger power supply occurs, A large current is discharged from the plasma power source into the discharge space at once, and the gas in the discharge space becomes a high-temperature and high-pressure plasma state, and is injected into the combustion chamber as a large volume plasma, igniting the mixture in the combustion chamber can do.

  According to the present invention, when an air discharge path is not formed due to a short circuit to the deposit, the deposit is removed by multiple trigger discharge or another air discharge path is formed, and volume plasma can be reliably injected. It becomes. On the other hand, when there is no deposit and volume plasma can be ejected by one trigger discharge, unnecessary trigger discharge can be avoided and excessive electrode consumption can be suppressed. Therefore, it is possible to realize a plasma ignition device that performs ignition of a highly ignitable internal combustion engine with extremely high reliability.

The outline | summary of the plasma ignition device 1 in the 1st Embodiment of this invention is demonstrated with reference to FIG. The plasma ignition device 1 includes a spark plug 10 mounted on a cylinder head 401 of an internal combustion engine 40 (not shown), and a high energy power source for supplying high energy to the spark plug 10. A plasma power source (MTPDS) 20 and an electronic control unit (ECU) 30 that generates an ignition signal in accordance with the operation status of the internal combustion engine 40 are configured.
MTPDS20 repeats the plurality of times of triggering discharge to draw large plasma current _{I PLZ} current amount as high energy _{(V TRG1, V TRG2, V} TRG3 ···) to the spark plug 10 receives an ignition signal from the ECU 30.

  In the present embodiment, the spark plug 10 includes a center electrode 11 made of a conductive metal material extending in a long axis shape, a substantially cylindrical insulator 12 covering the outer periphery of the center electrode 11, and a substantially cylindrical shape covering the insulator 12. A housing 13 made of metal and a substantially annular ground electrode 130 connected to the tip of the housing 13 are formed.

  A center electrode discharge part 110 formed in a thin-shaft shape by a heat-resistant conductive material such as iridium or an iridium alloy is provided on the tip side of the center electrode 11, and the center electrode discharge part 110 is formed of a conductive adhesive 111. Are connected to the central electrode central shaft portion 112 made of a metal material having good electrical conductivity and high thermal conductivity such as steel material and copper. A central electrode terminal portion 113 connected to the plasma power source 20 is formed on the proximal end side of the central electrode central shaft portion 112.

The insulator 12 is made of high-purity alumina or the like excellent in heat resistance, mechanical strength, high-temperature dielectric strength, thermal conductivity, and the like. A cylindrical insulator base 120 extending downward from the distal end of 110 is formed, and a large-diameter portion 121 that is locked to the inside of the housing 13 and is crimped and fixed by the housing 13 is formed in the middle. On the side, a corrugated insulator head portion 122 is formed to ensure electrical insulation between the center electrode terminal portion 112 and the housing 13.
Inside the insulator base 120, a discharge space 140 is formed, and discharge is possible between the center electrode discharge part 110 and the ground electrode 130.

The housing 13 is formed with a substantially cylindrical housing base 132 and covers the insulator base 120.
A screw part 133 for screwing to the internal combustion engine 40 is formed on the outer periphery of the housing base part 132, and a locking part 133 for holding the large insulator diameter part 121 is formed on the base end side. A hexagonal portion 134 for tightening the screw portion 133 is formed on the outer periphery on the base end side. The large-diameter insulator 121 is caulked and fixed by a caulking portion 135 via a sealing member or the like.

The ground electrode 130 is formed in a substantially annular shape having a ground electrode opening 131 communicating with the discharge space 140.
The housing 13 including the ground electrode 130 is formed of a metal material such as nickel or iron. The spark plug 10 is mounted so that the ground electrode opening 131 is opened in the combustion chamber 300 of the internal combustion engine 40, and the ground electrode 130 is electrically grounded to the internal combustion engine 40. The lower end surface of the center electrode discharge part 110 and the inner peripheral wall of the ground electrode 130 are exposed to the discharge space 140.

  In the present embodiment, when a high voltage is applied to the spark plug 10 from the MTPDS 20 a plurality of times in accordance with the ignition signal from the ECU 30, a plurality of trigger discharges are performed in the discharge space 140. At this time, deposits formed by incomplete combustion of the air-fuel mixture on the inner peripheral wall of the insulator 120 forming the discharge space 140, deposits of metal components of the electrode evaporated by sputtering during discharge causing channeling, etc. When the discharge current flows to the deposit as a resistor by a plurality of trigger discharges, the deposit generates heat and is removed by burning or re-transpiration due to sputtering. Further, even if the deposits are not completely removed by a plurality of trigger discharges, the discharge position may change, whereby the insulation in the discharge space 140 may be broken and an air discharge may occur.

When deposits are removed or another air discharge path is formed by a plurality of trigger discharges, which is the main part of the present invention, the insulation in the discharge space 140 is destroyed, and the plasma current I _PLZ is _generated in the discharge space 140. The gas in the discharge space 140 becomes a high-temperature and high-pressure plasma state and is injected into the combustion chamber 400 as a large volume plasma, and the air-fuel mixture in the combustion chamber 400 can be ignited.
On the other hand, when there is no deposit on the inner peripheral wall of the insulator 120 that partitions the discharge space 140, the insulation in the discharge space 140 is broken by the first trigger discharge from the MTPDS 20 and the plasma current I _PLZ is changed into the discharge space 140. The gas in the discharge space 140 becomes a high-temperature and high-pressure plasma state and is injected into the combustion chamber 400 as a large volume plasma, and the air-fuel mixture in the combustion chamber 400 can be ignited.

  Therefore, according to the present invention, when there is no deposit and volume plasma can be ejected by a single trigger discharge, unnecessary trigger discharge is avoided and excessive electrode consumption is suppressed, while If the air discharge path is not formed due to a short circuit, deposits are removed by multiple trigger discharges or another air discharge path is formed, and volume plasma injection is performed reliably to ignite a difficult-ignition internal combustion engine. A reliable plasma ignition device can be realized.

  FIG. 2 shows the effect of the plasma ignition device 1 in the first embodiment of the present invention. Comparative Example 1 shows the result of performing 100 times of ignition tests by performing one trigger discharge every time of ignition for the spark plug 10 in which deposits are present in the discharge space 140 as in the conventional case. In the first, second, third, fourth, fifth, and sixth embodiments, the trigger discharge is performed twice for each ignition for the spark plug 10 in which deposits are present in the discharge space 140. Shows the results of 100 ignition tests performed 4 times, 5 times, 6 times, and 7 times, the horizontal axis represents the number of trigger discharges n, and the vertical axis represents the occurrence frequency P (%).

As shown in Comparative Example 1, when only one trigger discharge was performed for each ignition, an ignition error in which the plasma current I _PLZ did not flow as many as 80 times out of 100 occurred. On the other hand, as shown in Examples 1 to 6, it is possible to flow the plasma current _IPLZ dramatically by performing the trigger discharge a plurality of times, and the trigger discharge is performed five times or more for one ignition. It was proved that ignition mistakes could be prevented reliably.

From this test, it is presumed that, when the test discharge is performed a plurality of times at intervals of trigger discharge, the plasma current _IPLZ may not be allowed to flow, as in Comparative Example 1.
Therefore, it is desirable that the multiple trigger discharges be performed in the compression stroke from BTDC 30 ° to TDC in accordance with the ignition timing, and at the timing when the respective discharge intervals of the multiple trigger discharges are open, for example, in the intake process or the exhaust process. Even if it is performed separately from the trigger discharge accompanied by ignition, it does not lead to improvement in ignitability, and it is presumed that there is a possibility of causing exhaustion of the electrode due to unnecessary discharge.

  This is because, in the compression process, the pressure and temperature in the discharge space 140 are high, and the deposit is heated and easily burned out. In addition, the discharge voltage is high, so the deposit is present. When trigger discharge is performed, the discharge current easily flows due to the deposit, self-heats due to the internal resistance of the deposit, is easily removed by burning or transpiration, and is triggered multiple times at the timing of ignition. It is presumed that another air discharge path is easily formed by discharging.

On the other hand, in the intake stroke and the exhaust stroke, since the pressure in the discharge space 140 is low and the discharge voltage is low, even if trigger discharge is performed, the discharge current does not flow to the deposit, and the air discharge is performed. There is also a risk that it will not be removed. In such a case, even if a normal one-time trigger discharge is performed in the compression stroke, the discharge voltage is high, so that the discharge current is short-circuited to the deposit, and the air discharge is not caused in the discharge space 140, and the plasma current I It is inferred that _PLZ will not flow.

A more specific configuration of the plasma ignition device 1a in the first embodiment of the present invention will be described with reference to FIG.
In the present embodiment, the multi-time trigger discharge plasma power supply MTPDS 20a includes a multi-time trigger discharge means 21a including a first trigger discharge circuit 210a and a second trigger discharge circuit 220a formed of a so-called CDI type discharge circuit, and an internal combustion engine. The electronic control unit ECU 30 that transmits an ignition signal according to the operation status of 40, and a trigger signal is selectively sent to either the first trigger discharge circuit 210a or the second trigger discharge circuit 220a according to the ignition signal from the ECU 30. The driving control unit EDU 31a that transmits and drives the trigger discharge means 21a a plurality of times, the plasma current circuit 23 that supplies a large current, and the spark plug 10 are configured.
A trigger signal is selectively transmitted from the EDU 31a to the first trigger discharge circuit 210a and the second trigger discharge circuit 220a, and a plurality of trigger discharges are alternately performed. When insulation in the discharge space is broken by a plurality of trigger discharges, a large current _IPLZ flows from the plasma current circuit 23, and the gas in the discharge space is ejected as volume plasma.

FIG. 4 shows an equivalent circuit of a plasma ignition device 1a ₁ as a more specific example of the plasma ignition device according to the first embodiment of the present invention.
In the present embodiment, the multiple-time trigger discharge means 21a is constituted by a first trigger circuit 210a and a second trigger circuit 220a connected in parallel. The first trigger circuit 210a and the second trigger circuit 220a are stored in power supplies 211a and 221a, resistors 212a and 222a, capacitors 213a and 223a that store voltages of the power supplies 211a and 221a, and capacitors 213a and 223a. voltage further the ignition coil 213a _1, 223a ₁ for boosting was composed of the ignition coil 215a _1, switching element 214a for opening and closing the 225a _1, a drive circuit including 224a, rectifier elements 216a for rectifying the trigger voltage, and 226a The same circuit is connected in parallel and connected to the spark plug 10 via a noise absorbing resistor 217a.

  The plasma current circuit 23 is connected to the spark plug 10, a power source 230 connected in parallel with the spark plug 10, a capacitor 232 that stores energy of the power source 230, and a resistor 233 connected between the power source 230 and the capacitor 232. And a rectifying element 233 that rectifies a large current discharged from the capacitor 232.

The power supplies 211a and 221a excite the primary coils of the ignition coils 215a ₁ and 225a _{1 and} the primary voltage is cut off by switching of the switching elements 214a and 224a ignition coil drive circuits 214a and 224a in accordance with an ignition signal from the ECU 30. Then, an induced current flows through the primary coil, and a high voltage is applied to the spark plug 10. At this time, since the switching elements 214a and 224a are alternately opened and closed at a predetermined timing by the EDU 31a, a plurality of trigger discharges are performed on the spark plug 10 at a predetermined timing. Even if deposits are present on the inner peripheral wall of the insulator 12, they are removed by a plurality of trigger discharges, or when another insulation discharge path is formed and the insulation in the discharge space 140 is destroyed, the discharge space The inside of 140 is in a state where current easily flows.

On the other hand, the capacitor 232 is charged by the power source 230. Along with the discharge to the spark plug 10, a large current flows from the capacitor 232 to the spark plug 10, and the gas in the discharge space 140 is ionized and injected as high-temperature and high-pressure volumetric plasma.
In this embodiment, the power supplies 211a, 221a, and 230 are set to 450v, the capacitor 232 is set to 2 _μF , and the discharge voltages V _TRG1 , V _TRG2 , V _TRG3. The discharge voltage is set to be small.
Furthermore, the discharge interval of the repeated trigger discharge is within 20 μsec.
The energy supplied from the capacitor 232 to the discharge space 140 is about 100 to 200 mJ.

FIG. 5 shows a plasma ignition device 1a ₂ as a modification of the plasma ignition device in the first embodiment of the present invention. In the present embodiment, the basic configuration is the same as that of the above-described embodiment, and the same reference numerals are given to the same configuration, and thus description thereof is omitted, and only differences are described. In the first trigger discharge circuit 210a ₂ and the second trigger discharge circuit 220a ₂ , the respective secondary circuits of the power sources 211a ₂ and 221a ₂ and the ignition coils 216a ₂ and 226a ₂ are shared by the respective circuits. It is different from the above embodiment. In the present embodiment, similarly to the above-described embodiment, a discharge path that performs a plurality of trigger discharges for each ignition to remove deposits present on the inner peripheral wall of the insulator 12 or to avoid deposits is provided. It is formed in the discharge space 140, and the air discharge is surely performed in the discharge space 140, and then the plasma current _IPLZ is released from the plasma current circuit, and the gas in the discharge space 140 is injected as high-temperature and high-pressure volumetric plasma. it can.

Figure 6 shows the plasma ignition system 1a ₃ as another modification of the plasma ignition system according to the first embodiment. The present embodiment is different in that piezoelectric transformers P _Z T _RS 219 and 229 are used instead of the ignition coils 216a and 226a as boosting circuits for boosting the power supplies 211a ₃ and 221a ₃ . In the present embodiment, similarly to the above-described embodiment, a discharge path that performs a plurality of trigger discharges for each ignition to remove deposits present on the inner peripheral wall of the insulator 12 or to avoid deposits is provided. It is formed in the discharge space 140, and the air discharge is surely performed in the discharge space 140, and then the plasma current _IPLZ is released from the plasma current circuit, and the gas in the discharge space 140 is injected as high-temperature and high-pressure volumetric plasma. it can. In addition, according to this embodiment, since the piezoelectric transformer performs capacitive discharge, the trigger discharge time is shortened, and excessive consumption of the electrodes can be suppressed.

FIG. 7 shows a plasma ignition device 1b as a reference example . In this reference example , the ECU 30 that emits an ignition signal according to the operating condition of the internal combustion engine 40, the EDU 31b that emits a trigger signal according to the ignition signal from the ECU 30, a plurality of trigger discharges V _TRG1 and V _TRG2 according to the trigger signal, is constituted by a large-current circuit 23 supplies a trigger discharge circuit 210b and the plasma current _{I PLZ} performing V _TRG3 · ·.

FIG. 8 is an equivalent circuit diagram showing a more specific configuration example of the plasma ignition device 1b in the reference example .

In the reference example shown in FIG. 8, the plasma current circuit 23 is connected to the spark plug 10, the power source 230 connected in parallel with the spark plug 10, the capacitor 232 that stores the energy of the power source 230, the power source 230, and the capacitor 232. A resistor 233 connected between the capacitor 232 and a rectifying element 233 that rectifies a large current discharged from the capacitor 232, and a current detection coil 218 that detects a plasma current or a current detector between the capacitor 232 and the ground. resistance that provided.
In the above embodiment, the current detection coil 218 shown in this reference example is combined, and the current detection coil 218 performs trigger discharge until it is confirmed that the plasma current I _PLZ flows from the plasma current circuit 23. It is also possible to suppress the trigger discharge.

FIG. 9 shows an outline of a plasma ignition device 1c in the third embodiment of the present invention. In the present embodiment, a plurality of charging and discharging means 213c _1, 213c ₂ and this charge-discharge unit 213c _1, the discharge delay means 218c and trigger discharge circuit for delaying discharge of 213c ₂ of the electrical energy of the power source performing charging and discharging 214c and 215c are provided, and when an ignition signal is received from the ECU 30, a plurality of trigger discharges are performed via the trigger circuits 214c and 215c with a time difference between the discharges from the charge / discharge units by the discharge delay unit. .

FIG. 10 is an equivalent circuit diagram showing a more specific configuration of the plasma ignition device 1c in the third embodiment of the present invention.
In this embodiment, capacitors 213c ₁ and 213c ₂ are provided as charge / discharge means, and a choke coil 218c is interposed between the capacitors 213c1 and 213c2 as discharge delay means. As the trigger circuit, there is provided a drive control device including an ignition coil 215c that further boosts the energy stored in the capacitors 231c1 and 213c2, and a switching element 214c that opens and closes the ignition coil 215c. When the switching element 214c is opened and closed by the ignition signal from the ECU 30, a high voltage induced by the energy stored in the capacitor 213c1 is applied to the spark plug 10 via the rectifying element 216c. Next, the energy stored in the capacitor 213c2 is delayed by the choke coil 218c, and the high voltage induced through the ignition coil 215c is applied to the spark plug 10 through the rectifying element 216c. For this reason, when a plurality of open high voltages are applied as a trigger discharge to the spark plug 10 and the insulation in the discharge space is broken, the energy in the capacitor 232 charged by the power source 230 is applied to the spark plug 10 via the rectifying element 217c. The gas in the discharge space 140 is supplied and ejected as volume plasma.

The present invention is not limited to the above-described embodiment, and a range that does not depart from the gist of the present invention in which deposits and the like existing in the discharge path are removed by performing trigger discharge a plurality of times to perform reliable ignition. It can be changed as appropriate.
For example, in the above embodiment, the plasma ignition device has been described in which the discharge space is formed inside the insulator and the high temperature and high pressure volume plasma is injected to ignite the engine. It is not limited.

  The spark plug includes a center electrode, an insulator that covers the center electrode, and an annular ground electrode that covers the insulator, so that the lower end surface of the center electrode and the lower end surface of the ground electrode are substantially flush with each other. Or, the lower end surface of the center electrode is arranged so as to protrude to the combustion chamber side from the lower end surface of the ground electrode, and the lower end surface of the insulator is exposed toward the combustion chamber, so that an extremely shallow discharge space is formed. The outer peripheral surface of the center electrode and the inner peripheral surface of the ground electrode may be formed so as to face the discharge space. Even in such a plasma ignition device using a so-called creeping discharge type ignition plug, a short circuit due to deposits or the like existing on the discharge path can be suppressed and reliable ignition can be performed.

  In addition, the spark plug includes at least a part of a center electrode, a cylindrical insulator that covers the outer periphery of the center electrode, and a substantially annular ground electrode that covers the outer periphery of the insulator. Further, the discharge space may be formed in the combustion chamber. In such plasma spark plugs using so-called spark plug type spark plugs and in plasma ignition devices using so-called creeping discharge spark plugs, short-circuiting due to deposits etc. existing on the discharge path can be achieved. Suppressing and reliable ignition can be performed.

  In the present invention, the type of fuel and the injection method of the internal combustion engine are not particularly limited.

1 is an overall view showing a configuration of a plasma ignition device according to a first embodiment of the present invention. The characteristic view which shows the effect of this invention with a comparative example. The block diagram which shows the outline | summary of the plasma ignition device in the 1st Embodiment of this invention. The equivalent circuit schematic which shows the specific example of the plasma ignition device in the 1st Embodiment of this invention. The equivalent circuit diagram which shows the modification of the plasma ignition device in the 1st Embodiment of this invention. The equivalent circuit diagram which shows the other modification of the plasma ignition device in the 1st Embodiment of this invention. The block diagram which shows the outline | summary of the plasma ignition device in a reference example . The equivalent circuit diagram which shows the specific example of the plasma type ignition device in a reference example . The block diagram which shows the outline | summary of the plasma type ignition device in the 3rd Embodiment of this invention. The equivalent circuit diagram which shows the specific example of the plasma ignition device in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma type ignition device 10 Plasma type spark plug 11 Center electrode 110 Center electrode discharge part 12 Insulator 120 Insulator base 13 Housing 130 Ground electrode 140 Discharge space 20 Multiple times trigger discharge plasma power supply (MTPDS)
30 Electronic control unit (ECU)
40 Internal combustion engine 400 Combustion chamber 401 Cylinder heads V _TRG1 , V _TRG2 , V _TRG3 ... Trigger discharge voltage I _PLZ plasma current

Claims (8)

As a spark plug having a discharge space partitioned by a center electrode, a ground electrode, and an insulator that insulates them, and a high energy power source for supplying high energy to the spark plug, multiple trigger discharges for each ignition And a plasma energy power source that supplies a large current to the discharge space that is broken down by the trigger discharge, and applies high energy from the high energy power source to the gas in the discharge space. A plasma ignition device that ignites an air-fuel mixture of an internal combustion engine in a high temperature and high pressure plasma state,
The multi-time trigger power supply comprises a plurality of trigger discharge circuits, each trigger discharge circuit including a capacitor as energy storage means for storing a power supply voltage, and a coil as boosting means for boosting the discharge voltage from the energy storage means Comprising
Each trigger discharge circuit is connected in parallel to the spark plug,
While performing the above-described multiple trigger discharges in the ignition process from BTDC 30 ° to TDC ,
The plasma ignition device characterized in that the discharge interval of the repeated trigger discharge is within 20 μs . As a spark plug having a discharge space partitioned by a center electrode, a ground electrode, and an insulator that insulates them, and a high energy power source for supplying high energy to the spark plug, multiple trigger discharges for each ignition And a plasma energy power source that supplies a large current to the discharge space that is broken down by the trigger discharge, and applies high energy from the high energy power source to the gas in the discharge space. A plasma ignition device that ignites an air-fuel mixture of an internal combustion engine in a high temperature and high pressure plasma state,
The multi-time trigger power supply comprises a plurality of trigger discharge circuits, each trigger discharge circuit stores a power supply voltage, and includes a piezoelectric transformer as energy storage means for generating a high voltage,
Each trigger discharge circuit is connected in parallel to the spark plug,
While performing the above-described multiple trigger discharges in the ignition process from BTDC 30 ° to TDC ,
The plasma ignition device characterized in that the discharge interval of the repeated trigger discharge is within 20 μs .   The multi-time trigger power source is any one of an electronic control unit that generates an ignition signal according to an operating state of the internal combustion engine, and a multi-time trigger signal that generates a multi-time trigger signal in response to the ignition signal. A plasma ignition device according to claim 1 or 2, further comprising a trigger discharge circuit selection control device for selectively controlling the discharge.   The multi-time trigger power supply includes a discharge delay means for delaying a discharge from the energy storage means, and the discharge delay means provides a time difference in the multiple discharges from the boosting means. The plasma ignition device according to any one of 1 to 3.   2. The multi-time trigger power supply includes plasma current detection means for detecting a large current flowing from the plasma power supply, and the trigger discharge is stopped when the plasma current is detected. 5. The plasma ignition device according to any one of items 4 to 4.   The spark plug includes at least a part of a center electrode, a cylindrical insulating member that covers the outer periphery of the center electrode, and a substantially annular ground electrode that covers the outer periphery of the insulating member. 6. The plasma ignition device according to claim 1, wherein the plasma ignition device is damped.   The spark plug includes a center electrode, an insulator that covers the center electrode, and an annular ground electrode that covers the insulator, and the lower end surface of the center electrode and the lower end surface of the ground electrode are substantially flush with each other. Or the lower end surface of the center electrode protrudes to the combustion chamber side with respect to the lower end surface of the ground electrode, and the lower end surface of the insulator is exposed toward the combustion chamber, so that an extremely shallow discharge space is provided. 6. The plasma ignition device according to claim 1, wherein an outer peripheral surface of the center electrode and an inner peripheral surface of the ground electrode are opposed to the discharge space. The spark plug includes at least a part of a center electrode, a cylindrical insulator that covers the outer periphery of the center electrode, and a substantially annular ground electrode that covers the outer periphery of the insulator. 6. The plasma ignition device according to claim 1, wherein the plasma ignition device is damped.

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