JP2012089289A - Internal combustion engine ignition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine ignition device, exhibiting excellent ignitability and durability even in a hard-to-ignite internal combustion engine.SOLUTION: An ignition plug 10 is provided in a position in which a discharge space 140 internally sectioned in an insulator 12 and having one end closed and another end opened toward a combustion chamber 300 of an internal combustion engine 30 is led into the anti-combustion chamber side, on the top end side of a center electrode 11. One of the top end face 111 of the center electrode 11 and the surface of the opening 133 of the ground electrode 132 is covered with a discharge space partition wall 122 composed of a portion of the insulator 12, while another is exposed in the discharge space 140. A high energy power supply 20 applies a high frequency wave having a prescribed frequency to generate nonequilibrium plasma having high electron temperature and low molecule temperature, in the discharge space 140 for a prescribed application time.

Description

  The present invention relates to an internal combustion engine ignition device that is mounted on a hardly ignitable combustion engine and ignites the combustion engine.

Recently, from the viewpoint of CO ₂ reduction, high supercharge to achieve high output in a small, high compression automobile engines, and high efficiency, the development of the engine such as to achieve low NO _X is promoted.
In the case of a high-supercharged, high-compression automobile engine, the in-cylinder pressure before ignition is high, and therefore, when igniting with a spark ignition plug, it is necessary to increase the energy supplied to the ignition plug several times that of the prior art.
Further, in the case of a generator engine for a cogeneration system, the cylinder bore diameter is large and the air-fuel mixture concentration is also lean.
In order to burn such an inflammable internal combustion engine with high efficiency, an ignition device having a high combustion speed and excellent ignitability is desired.

  As an ignition device that exhibits excellent ignitability even in a non-ignitable internal combustion engine or the like, 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 It breaks the insulation in the discharge space by applying a high voltage, and this is used as a trigger to supply a large current to the discharge space to inject high-temperature and high-pressure plasma into the mixture of the internal combustion engine. Plasma ignition devices that ignite are expected and various proposals have been made (for example, see Patent Document 1, Patent Document 2, Patent Document 3, and the like).

However, in the conventional plasma ignition device, good ignition can be expected even in a difficult-ignition internal combustion engine, but at a very high temperature and high pressure, a plasma having a large mass collides with the electrode and causes the electrode to be consumed.
For this reason, with a long-term use, the discharge distance gradually increases, the required high voltage applied to break the insulation of the discharge space increases, and there is a possibility that it will become impossible to discharge.

  Therefore, in view of such circumstances, the present invention focuses on the fact that non-equilibrium plasma (low temperature plasma) having a high electron temperature and a low molecular temperature can be generated by applying a high frequency of a specific range of frequencies and application times. An object of the present invention is to provide an internal combustion engine ignition device that exhibits excellent ignitability even in a difficult-ignition internal combustion engine and exhibits high durability by using non-equilibrium plasma. .

In the first invention, a substantially cylindrical insulator mounted on the internal combustion engine, a long-axis-shaped center electrode held at the center of the insulator, disposed at the tip of the insulator, and open to the inside An internal combustion engine ignition device comprising a spark plug comprising a substantially annular ground electrode provided with a high energy power source for supplying high energy to the spark plug,
The spark plug is partitioned inside the insulator and has a discharge space in which one end is closed and the other end is opened toward the combustion chamber of the internal combustion engine. It is in a position that is retracted to the anti-combustion chamber side from the upper surface,
Either one of the front end surface of the center electrode and the surface of the opening of the ground electrode is covered with a discharge space partition wall made of a part of the insulator, and the other is exposed to the discharge space,
The high energy power source applies a high frequency of a predetermined frequency that generates non-equilibrium plasma having a high electron temperature and a low molecular temperature in the discharge space to the spark plug for a predetermined application time.

According to the first invention, since either the front end surface of the center electrode or the surface of the opening of the ground electrode is covered with the discharge space partition wall, the high-energy power source is connected to the spark plug. When the high frequency is applied, non-equilibrium plasma is generated in the discharge space without causing arc discharge between the center electrode and the ground electrode, and is introduced into the discharge space by an extremely high electron temperature. The air-fuel mixture is excited to form a flame, which is ejected from the opening of the ground electrode into the combustion chamber, ignites the air-fuel mixture in the combustion chamber, and the combustion spreads.
At this time, since there is no arc discharge, almost no current flows between the center electrode and the ground electrode, and the supplied energy can be effectively used for combustion of the air-fuel mixture, so that the electrode is hardly consumed. Become.
In addition, even when a strong air flow is generated in the combustion chamber, the air-fuel mixture is ignited in the discharge space defined in the insulator, so that non-equilibrium plasma is not blown off in the in-cylinder air flow. Ignition can be realized.

  In the second invention, the thickness of the discharge space partition wall covering either the front end surface of the center electrode or the surface of the opening of the ground electrode is designed to insulate the center electrode from the ground electrode. Make it thinner than the thickness of the insulator.

  According to the second invention, when a high voltage is applied from the high energy power source between the center electrode and the ground electrode, the insulation between the center electrode and the ground electrode is ensured and the discharge space is entered. Therefore, non-equilibrium plasma is likely to be generated in the discharge space, electrode consumption is suppressed, and a highly durable internal combustion engine ignition device can be realized.

  In the third invention, the oscillation frequency when the high energy power source applies a high voltage to the spark plug at a high frequency is 1 MHz or more and 50 MHz or less.

According to the third aspect of the present invention, non-equilibrium plasma can be generated in the discharge space without causing arc discharge that generates equilibrium plasma having a high molecular temperature between the center electrode and the ground electrode.
Therefore, it is possible to realize an ignition device that can maintain stable ignition for a long period of time without causing electrode consumption due to equilibrium plasma.
On the other hand, regardless of the present invention, when the high-frequency oscillation frequency is higher than 50 MHz, plasma is difficult to generate, and when the high-frequency transmission frequency is lower than 1 MHz, the non-equilibrium plasma easily transitions to the equilibrium plasma. Equilibrium plasma with high temperature and high mass is likely to collide with the electrode and cause consumption.

  More desirably, as in the fourth aspect of the invention, the oscillation frequency when the high energy power source applies a high voltage to the spark plug at a high frequency is 4 MHz or more and 10 MHz or less.

According to the fourth invention, the electron temperature of the non-equilibrium plasma generated by the application of a high voltage from the high energy power source is 1.16 × 10 ⁵ K (10 eV) or more, and the mixing introduced into the discharge space is performed. Reactivity with qi is improved.

  In 5th invention, the application time when the said high energy power supply applies a high voltage within one period is 1 ns or more and 250 ns or less.

According to the fifth aspect of the present invention, non-equilibrium plasma can be generated in the discharge space without causing arc discharge that generates equilibrium plasma having a high molecular temperature between the center electrode and the ground electrode.
Therefore, it is possible to realize an ignition device that can maintain stable ignition for a long period of time without causing electrode consumption due to equilibrium plasma.
On the other hand, regardless of the present invention, when the high voltage application time is shorter than 1 ns, it is difficult to generate plasma, and when the high voltage application time is longer than 250 ns, the non-equilibrium plasma easily transitions to the equilibrium plasma. Equilibrium plasma having a high molecular temperature and a large mass is likely to be consumed by colliding with the electrode.

  More desirably, as in the sixth aspect of the invention, the application time during which the high energy power source applies a high voltage within one cycle is 10 ns or more and 100 ns or less.

According to the sixth aspect of the invention, the electron temperature of the non-equilibrium plasma generated by applying a high voltage from the high energy power source becomes 1.16 × 10 ⁵ K (10 eV) or more, and the mixing introduced into the discharge space. Reactivity with qi is improved.

  In a seventh aspect of the invention, a center electrode protrusion that protrudes toward the discharge space is provided on a part of the tip surface of the center electrode.

  In an eighth aspect of the invention, an insulating protrusion that protrudes into the discharge space is provided on a part of the inner peripheral surface of the insulator that partitions the discharge space.

According to the seventh invention or the eighth invention, when a high voltage is applied from the high energy power source to the spark plug, the protrusion of any one of the center electrode protrusion and the insulator protrusion The electric field strength at the portion is increased, and discharge into the discharge space is facilitated.
Therefore, the required voltage of the high voltage supplied from the high energy power source required for generating the non-equilibrium plasma in the discharge space can be lowered, so that the non-equilibrium plasma is easily generated and the equilibrium plasma is generated. Since it becomes difficult, it is expected that the consumption of the electrode can be further suppressed.

  In the ninth invention, the inner diameter of the discharge space is increased larger than the outer diameter of the center electrode, and the inner diameter of the opening of the ground electrode is reduced smaller than the outer diameter of the center electrode.

  According to the ninth aspect of the present invention, the jet pressure of the flame generated in the discharge space is increased, the spread of the flame into the combustion chamber is promoted, and improvement in ignitability can be expected.

The schematic diagram which shows the outline | summary of the internal combustion engine ignition device in the 1st Embodiment of this invention. The principal part sectional view for explaining the effect of the internal-combustion-engine ignition device in the 1st embodiment of the present invention. 2 shows an ignition control method applicable to the internal combustion engine ignition device according to the first embodiment of the present invention, where (a) is a time chart when ignition is performed with a single pulse, and (b) is ignition with a plurality of pulses. If time chart, The principal part sectional drawing which shows the outline | summary of the internal combustion engine ignition device in the 2nd Embodiment of this invention. The perspective view which shows the difference in the shape of a center electrode as a modification of the internal combustion engine ignition device in the 2nd Embodiment of this invention from (a) to (d). The internal combustion engine ignition device in the 3rd Embodiment of this invention and its principal part sectional drawing shown to the modification (a) to (c). The internal combustion engine ignition device in the 4th Embodiment of this invention, its modification, and the principal part sectional drawing which respectively show the internal combustion engine ignition device in 5th Embodiment from (a) to (c).

The present invention, high supercharging, high-compression, high EGR, high efficiency, engine ignition exhibiting excellent ignitability and durability used in flame ignition of the internal combustion engine such as an engine to achieve low NO _X by the lean burn Device.
With reference to FIG. 1, the outline | summary of the internal combustion engine ignition device 1 in the 1st Embodiment of this invention is demonstrated.
The internal combustion engine ignition device 1 uses a non-equilibrium plasma ignition plug 10 provided in an unillustrated internal combustion engine 30 and having a tip exposed to the engine combustion chamber 300 as an ignition plug. A high-frequency voltage of a predetermined frequency is applied from a high-energy power supply 20 that supplies high energy to the spark plug 10 for a predetermined application time to partition the non-equilibrium plasma inside the insulator 12 of the non-equilibrium plasma spark plug 10. The air-fuel mixture generated in the discharge space 140 is ignited and injected into the combustion chamber 300 to ignite the air-fuel mixture introduced into the combustion chamber 300. .
Excitation of the electrode due to the high temperature plasma by exciting the combustion reaction of the air-fuel mixture introduced into the discharge space 140 by non-equilibrium plasma with high electron temperature and low molecular temperature without generating high temperature plasma in the discharge space 140 The point that suppresses is the greatest feature.

The non-equilibrium plasma spark plug 10 according to the present embodiment includes an insulator 12 formed in a substantially cylindrical shape using an insulating heat-resistant material such as alumina, and a highly conductive metal material such as nickel held at the center thereof. A central electrode 11 formed in a long axis shape, a housing 13 formed in a substantially cylindrical shape using a conductive material and holding the insulator 12, and extended to the housing 13 and disposed at the tip of the insulator 12. And a substantially annular ground electrode 132 having an opening 133 on the inside, and either the tip surface 111 of the center electrode 11 or the inner peripheral surface of the ground electrode 132 is not shown in the drawing. The discharge space partition wall 122 is made of, and arc discharge is not generated between the center electrode 11 and the ground electrode 132 when a high voltage is applied under the conditions described later.
The non-equilibrium plasma spark plug 10 is attached to the internal combustion engine 30 and exposes the opening 133 of the ground electrode 132 in the combustion chamber 300.
Further, the non-equilibrium plasma spark plug 10 is partitioned inside the insulator 12 and has a discharge space 140 in which one end is closed and the other end is opened toward the combustion chamber 300 of the internal combustion engine 30. Therefore, the internal combustion engine 30 is in a position retracted to the anti-combustion chamber side from the upper surface of the combustion chamber 300.

In the present embodiment, the front end surface 111 of the center electrode 11 is covered with a part 122 of the insulator 12, and the surface of the opening 133 of the ground electrode 132 is exposed to the discharge space 140.
A high frequency voltage is applied from the high energy power source 20 to the center electrode terminal portion 110 on the proximal end side of the center electrode 11.
The base end side of the insulator 12 constitutes an insulator head 120 exposed from the housing 13, and the distance between the center electrode terminal portion 110 and the housing is increased to ensure insulation between the two. Yes.
An insulator fixing portion 121 corresponding to the middle of the insulator 12 is expanded in the outer diameter direction and is held by the housing holding portion 130.
A part of the insulator 12 is used as a discharge space partition wall 122 to cover the front end surface 111 of the center electrode 11 as one electrode of the center electrode 11 and the ground electrode 132 facing the discharge space 140, and the ground electrode 132 as the other electrode. The opening 133 is exposed to the discharge space 140.

In addition, a discharge space 140 is partitioned inside the insulator 12 by an insulator discharge space partition portion 123 that extends to the insulator fixing portion 121 and extends in a cylindrical shape downward from the front end surface 111 of the center electrode.
Extending to the housing 13 so as to cover the outer periphery of the insulator 12, a ground electrode side surface portion 131 is formed, covering the lower end surface of the insulator 12 and grounding so as to communicate with the opening on the front end side of the discharge space 140. The ground electrode 132 is disposed in a substantially annular shape provided with the electrode opening 132.
A screw part 134 is formed on the outer periphery of the ground electrode side part 131, and the opening 132 is fixed so as to be exposed to the combustion chamber 300 of the internal combustion engine 30.
The thickness of the discharge space partition wall 122 covering either the front end surface 111 of the center electrode 11 or the surface of the opening 1133 of the ground electrode 132 is such that the insulation in the lateral direction between the center electrode 11 and the ground electrode 132 is achieved. Insulating leakage between the side surface of the center electrode 11 and the ground electrode 132 or the housing 13 is less likely to occur when a high voltage is applied. Corona discharge that extends in a streamer shape into the discharge space 140 that is opposed to each other via 122 is easily generated.

As a result of intensive studies and tests by the present inventors, non-equilibrium plasma is generated by setting the oscillation frequency when the high energy power supply 20 applies a high voltage to the non-equilibrium plasma spark plug 10 at a high frequency to 1 MHz to 50 MHz. It becomes easy to make transition to equilibrium plasma, and it is found that non-equilibrium plasma with an electron temperature of 1.16 × 10 ⁵ (10 eV) or more can be generated by setting it to 4 MHz or more and 10 MHz or less. did.
Further, by setting the application time for applying a high voltage within one cycle from the high energy power source 20 to the nonequilibrium plasma spark plug 10 to 1 ns or more and 250 ns or less, non-equilibrium plasma with high electron temperature and low molecular temperature is generated. Furthermore, it was found that by setting the time to 10 ns or more and 100 ns or less, non-equilibrium plasma having an electron temperature of 1.16 × 10 ⁵ (10 eV) or more can be generated.
Further, by generating a non-equilibrium plasma in the discharge space 140, the electron temperature is introduced into the discharge space 140 instead of transitioning from a non-equilibrium plasma having a high electron temperature and a low molecular temperature to an equilibrium plasma having a high molecular temperature. A combustion reaction of the air-fuel mixture is caused, and a flame expanded by the combustion is ejected from the discharge space 140 into the combustion chamber 300 at a high pressure.
For this reason, electrode consumption due to collision of high-temperature plasma hardly occurs on the surface of the opening 133 of the ground electrode 132 exposed in the discharge space 140. Further, since plasma does not collide with the center electrode front end surface 111 covered with the discharge space partition wall portion 122, electrode consumption is less likely to occur.

On the other hand, regardless of the present invention, if the application time of the high voltage from the high energy power supply 20 to the spark plug is 1 ns or less, non-equilibrium plasma is hardly generated, and if it is 250 ns or more, the transition from non-equilibrium plasma to equilibrium plasma occurs. As a result, it is easy to cause arc discharge, and there is a risk that the electrode of the spark plug may be consumed by collision of a high molecular plasma, and a high electron temperature is not used for combustion of the air-fuel mixture, but the molecular temperature rises. Therefore, there is a possibility that about 40% of the energy given from the high energy power source is lost.
Further, regardless of the present invention, when the high frequency oscillation frequency is higher than 50 MHz, non-equilibrium plasma is hardly generated, and when the high frequency oscillation frequency is lower than 1 MHz, the non-equilibrium plasma is changed to the equilibrium plasma. Equilibrium plasma having a high molecular temperature and a large mass collides with the electrode exposed to the discharge space, and hence the electrode is easily consumed.

With reference to FIG. 2, the effect of this invention is further explained in full detail.
Fuel is injected into the combustion chamber 300 from a fuel injection device (not shown), and in the compression stroke, a mixture of air and fuel in the combustion chamber 300 is introduced into the discharge space 140 that communicates with the combustion chamber 300, resulting in high energy. When a high-frequency voltage is applied from the power source 20 at a predetermined transmission frequency for a predetermined application time, a streamer shape is formed from the inner peripheral surface of the insulator partition wall 122 covering the center electrode tip surface 111 into the discharge space 140. An extending corona discharge is generated, and a non-equilibrium plasma is formed in the discharge space 140 with a high electron temperature and a low molecular temperature.
At this time, between the center electrode 11 and the ground electrode side surface portion 131, and between the center electrode tip surface 111 and the inner peripheral wall of the opening 133 of the ground electrode 132 facing each other through the discharge space partition wall portion 122 and the discharge space 140. However, the thickness t ₁ of the discharge space partition wall 122 is formed to be much thinner than the thickness t ₂ of the insulator side surface 121, and the center electrode 11 and the ground electrode Insulation is ensured between the side surface portion 131 and corona discharge is formed in the discharge space 140 having higher electric field strength, so that no arc discharge occurs between the center electrode tip surface 111 and the ground electrode 132.
For this reason, almost no current flows between the center electrode 11 and the ground electrode 132, and the energy applied from the high energy power supply 20 can be efficiently used for the formation of non-equilibrium plasma.
The air-fuel mixture introduced into the discharge space 140 is excited by extremely high-temperature electrons, expands by a combustion reaction, and becomes a high-pressure flame from the discharge space 140 partitioned into a constant volume in the combustion chamber 300. And the air-fuel mixture in the combustion chamber 300 is burned.

A control method of the internal combustion engine ignition device 1 according to the first embodiment of the present invention will be described with reference to FIG.
This figure (a) shows the time chart in the case of applying a high voltage by a single pulse from the high energy power supply 20, and this figure (b) is the time in the case of applying a high frequency high voltage that oscillates a plurality of pulses. A chart is shown.
The ignition signal IGt is transmitted to the high energy power source 20 from an engine control device, which is not described in detail, for controlling the operation of the internal combustion engine 30 in accordance with the operation status of the internal combustion engine 30. As shown, a high energy power source is opened and closed at an oscillation frequency of 1 MHz to 50 MHz, and a high voltage is applied for a period of 1 ns to 250 ns per cycle.
In the case of a plurality of pulses, as shown in FIG. 7B, the high energy power source is opened and closed several times at an oscillation frequency of 1 MHz to 50 MHz with respect to one ignition signal IGt, and the drive pulse is opened and closed. Accordingly, a high voltage is applied a plurality of times for a period of 1 ns to 250 ns per cycle.

A non-equilibrium plasma spark plug 10a used in an internal combustion engine ignition device 1a according to a second embodiment of the present invention will be described with reference to FIG.
The same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Characteristic parts of this embodiment will be described in detail.
In the present embodiment, a protrusion 112 is formed by projecting a part thereof toward the discharge space partition wall 122 side along the outer peripheral edge of the center electrode front end surface 111a.
Thus, by providing the center electrode protrusion 112 on a part of the center electrode front end surface 111a, the electric field concentrates on the center electrode protrusion 112, and from the position facing the center electrode protrusion 112 of the discharge space partition wall 122. The required voltage required for generating non-equilibrium plasma in the discharge space 140 can be reduced.
According to this embodiment, it is expected that the consumption of the electrode can be further suppressed by lowering the voltage applied from the high energy power supply 20.
In addition, by adopting such a configuration, it is possible to reduce the size of the high energy power supply 20 and to reduce the manufacturing cost.

5 (a) to 5 (c) show a center electrode 10a used in the non-equilibrium plasma spark plug 10a in the second embodiment of the present invention and its modification.
As shown in this figure (a), the center electrode protrusion 112 may be provided over the entire outer periphery of the center electrode tip surface 111a, or as shown in this figure (b), the center electrode protrusion 112b may be provided at a part of the outer peripheral edge of the center electrode front end surface 111b.
Further, a plurality of center electrodes 112c may be provided on the surface of the center electrode tip surface 111c as shown in FIG. 10C, and the center electrode tip surface 111d is tapered as shown in FIG. Thus, the center electrode protrusion 112d may be formed.
In either case, electric field concentration occurs in the center electrode protrusions 112a, 112b, 112c, and 112d, the applied voltage is reduced, and consumption of the ground electrode 132 can be further suppressed.

With reference to FIG. 6, the non-equilibrium plasma spark plug 10e and its modifications 10f and 10g in the third embodiment of the present invention will be described.
In the second embodiment of the present invention, the example in which the protrusion is provided on the tip end surface 111 of the center electrode has been shown. However, as in the present embodiment, as shown in FIG. An insulator protrusion 124e protruding toward the inside of the discharge space 140 may be formed on the surface, or an insulator protrusion 124f protruding toward the inside of the discharge space may be formed on the inner peripheral wall of the insulator discharge space partition part 123f. It may be formed.
In either case, electric field concentration occurs in the protrusions 124e and 124f, and discharge becomes easy. Therefore, in order to generate non-equilibrium plasma in the discharge spaces 140e and 140f, the voltage applied from the high energy power source 20 is lowered, The consumption of the ground electrode 132 can be suppressed.
In addition, as shown in the figure (c) of the discharge space, a part of the tip side of the ground electrode 132g may be expanded to form the discharge space expanding portion 141. By adopting such a shape, the ground electrode 132g has a structure projecting relatively toward the discharge space 140, causing electric field concentration, reducing the applied voltage, and suppressing the consumption of the ground electrode 132g.
In addition, according to this embodiment, since the combustion flame ejected from the discharge space 140g generates a vortex in the discharge space expanding portion 141, the penetration force into the combustion chamber 300 increases or the mixing with the air-fuel mixture becomes active. As a result, further improvement in ignitability can be expected.

With reference to FIG. 7, the non-equilibrium plasma ignition plug 10h and its modification 10i in the fourth embodiment of the present invention and the non-equilibrium plasma ignition plug 10j in the fifth embodiment will be described.
In the above embodiment, the inner diameters of the discharge spaces 140 and 140 a to g are formed to be substantially equal to the outer diameter of the center electrode 11, and the opening 133 of the ground electrode 132 is formed to have the same inner diameter so as to communicate with the discharge space 140. As shown in FIG. 5A, in the non-equilibrium plasma spark plug 10h, the inner diameter of the discharge space 140h is larger than the outer diameter of the center electrode 11, and the opening of the ground electrode 132h is further shown. The inner diameter of the portion 133 h is formed to be smaller than the outer diameter of the center electrode 11.
By forming the discharge space 140h in this way, the ignitability is improved by increasing the jet pressure of the air-fuel mixture that causes the combustion reaction by the non-equilibrium plasma generated in the discharge space 140, and the applied voltage is lowered to improve durability. It can also improve the performance. Also in this embodiment, insulator protrusions 124h and 126 that protrude toward the inside of the discharge space 140h may be provided on a part of the insulator 12h.
Further, an insulator diameter-reduced portion 125h is provided so as to cover the surface of the ground electrode 132h facing the discharge space 140h so that the surface of the ground electrode 132h facing the discharge space 140h is not exposed to the discharge space 140h.
Further, as shown in FIG. 5B, in the non-equilibrium plasma spark plug 10i, a part of the tip side of the ground electrode 132i may be enlarged to form the discharge space expanding portion 141i.
Moreover, in the said embodiment, although the front end surface 111, 111a side of the center electrode 11 was covered with the discharge space partition part 122,122a-122i, it was made not to be exposed to the discharge space 140,140a-140i, this figure (c). As shown in the non-equilibrium plasma spark plug 10j in the fifth embodiment of the present invention, the tip surface 111j of the center electrode 11j is exposed to the discharge space 140j, and the opening 133j of the ground electrode 132j is formed by the insulator partition wall 122j. It may be covered. Similar to the above embodiment, the thickness t ₁ j of the insulator partition wall portion 122j is formed to be much thinner than the thickness t ₂ of the insulator discharge space partition portion 123. Furthermore, a modification of the above embodiment may be applied in combination with this embodiment.
In any case, as in the above embodiment, non-equilibrium plasma is generated in the discharge space 140j, the combustion reaction of the air-fuel mixture introduced in the discharge space 140j is caused, and the mixture is ejected into the combustion chamber 300. The air-fuel mixture can be ignited while suppressing the consumption of the electrodes.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine ignition device 10 Non-equilibrium plasma ignition plug 11 Center electrode 110 Center electrode base end part 111 Center electrode front end part 12 Insulator 120 Insulator head part 121 Insulator side face part 122 Discharge space partition part 123 Insulator discharge space partition part 13 Housing 130 Housing holding portion 131 Ground electrode side surface portion 132 Ground electrode 133 Ground electrode opening portion 134 Ground electrode screw portion 140 Discharge space 20 High energy power source 30 Internal combustion engine 300 Combustion chamber

US Pat. No. 3,581,141 Special table 2008-156035 JP 2010-153330 A

Claims (9)

A substantially cylindrical insulator mounted on an internal combustion engine, a long-axis center electrode held at the center of the insulator, a substantially annular shape provided at the tip of the insulator and provided with an opening inside An internal combustion engine ignition device comprising a spark plug comprising a ground electrode and a high energy power source for supplying high energy to the spark plug,
The spark plug is partitioned inside the insulator and has a discharge space in which one end is closed and the other end is opened toward the combustion chamber of the internal combustion engine. It is in a position that is retracted to the anti-combustion chamber side from the upper surface,
Either one of the front end surface of the center electrode and the surface of the opening of the ground electrode is covered with a discharge space partition wall made of a part of the insulator, and the other is exposed to the discharge space,
The internal combustion engine, wherein the high energy power source applies a high frequency having a predetermined frequency for generating non-equilibrium plasma having a high electron temperature and a low molecular temperature in the discharge space to the spark plug for a predetermined application time. Ignition device.   The thickness of the discharge space partition wall covering either the front end surface of the center electrode or the surface of the opening of the ground electrode is smaller than the thickness of the insulator for insulating the center electrode from the ground electrode. The internal combustion engine ignition device according to claim 1.   The internal combustion engine ignition device according to claim 1 or 2, wherein an oscillation frequency when the high energy power source applies a high voltage to the ignition plug at a high frequency is 1 MHz or more and 50 MHz or less.   The internal combustion engine ignition device according to any one of claims 1 to 3, wherein an oscillation frequency when the high energy power source applies a high voltage to the ignition plug at a high frequency is 4 MHz or more and 10 MHz or less.   The internal combustion engine ignition device according to any one of claims 1 to 4, wherein an application time during which the high energy power source applies a high voltage within one cycle is 1 ns or more and 250 ns or less.   The internal combustion engine ignition device according to any one of claims 1 to 5, wherein an application time during which the high energy power source applies a high voltage within one cycle is 10 ns or more and 100 ns or less.   The internal combustion engine ignition device according to any one of claims 1 to 6, wherein a center electrode protrusion portion protruding toward the discharge space is provided on a part of a front end surface of the center electrode.   The internal combustion engine ignition device according to any one of claims 1 to 7, wherein an insulating protrusion that protrudes toward the discharge space is provided on a part of an inner peripheral surface of the insulator that partitions the discharge space.   9. The discharge space according to claim 1, wherein the inner diameter of the discharge space is larger than the outer diameter of the center electrode, and the inner diameter of the opening of the ground electrode is smaller than the outer diameter of the center electrode. The internal combustion engine ignition device according to claim.

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