JP2010272323A - Plasma ignition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma ignition device performing ignition by injecting gas in a plasma state into an engine which facilitates the growth of a flame kernel and has an excellent ignition property and excellent durability. <P>SOLUTION: A plasma ignition device 1 is arranged to partition a discharge space 140 by a central electrode 110, a substantially cylindrical insulator 120 extending downward below a lower end surface of the electrode, and a grounding electrode 130 having an opening 131 communicating with an opening of the insulator to perform the application of a high voltage and the supply of a large current to the discharge space 140 to put the gas within the discharge space 140 in the plasma state, and to inject the gas into a combustion chamber 400 of an engine for ignition. As an eddying flow forming means for forming a plurality of eddying flows that are oriented to the center from their outer circumferences and different in moving velocity for a flow of a plasma jet PZ jetted from the discharge space 140, there is provided a shroud 15 having an eddying flow forming space 141 partitioned by peripheral walls 150, 151 surrounding the opening 131 and partially differing in height from each other at an front end side of the grounding electrode 130. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an improvement in ignitability 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, in order to further reduce environmentally hazardous substances such as nitrogen oxides and carbon dioxide contained in combustion exhaust gas, further improvement in fuel consumption and lean combustion are desired. .
As an engine capable of simultaneously improving the combustion efficiency of the engine and reducing the environmental load, it is impossible to propagate the flame with a spark plug using a conventional spark discharge by injecting gas in a high-temperature and high-pressure plasma state into the engine combustion chamber. A method for efficiently burning a lean air-fuel mixture has attracted attention.

As such a plasma ignition device, Patent Document 1 includes a housing having an opening portion and a bottom surface facing the opening portion and defining a chamber having a circular section extending in the axial direction, and a surface of the housing. An external electrode having an external electrode hole communicating with the opening of the chamber and the outside; and a center electrode disposed on the bottom surface of the chamber, and a voltage between the center electrode and the external electrode Is applied to the plasma ignition device for an internal combustion period in which plasma is generated in the chamber and a plasma jet is ejected from the opening of the chamber, the volume of the chamber being 10 mm ³ or less, and the axis of the chamber A plasma ignition device for an internal combustion engine is disclosed in which the aspect ratio between the length of the direction and the length of the inner diameter is 2 or more.

  According to the plasma ignition device of Patent Document 1, the reach distance when the gas in a high-temperature and high-pressure plasma state is injected in the chamber is increased, and the fuel concentration in the air-fuel mixture is relatively increased in the lean stratified combustion engine. It was expected that the ignitability of the lean fuel engine could be improved.

However, in such a plasma ignition device, the insulation in the discharge space is broken by the application of a high voltage, and a large current is supplied into the discharge space because it is very short, 10 μsec or less, and is injected into the engine combustion chamber. The time in which the gas in the plasma state can maintain the high energy state is extremely short.
For this reason, in order for flame nuclei to grow and propagate to the air-fuel mixture in the engine combustion chamber to cause ignition, for example, it was necessary to supply a relatively high energy of 200 mJ. In addition, there is a limit to the dilution of the combustible mixture while supplying such high energy. Further, when such high energy is supplied, the electrode is consumed very much, which limits the improvement of durability and reliability as a plasma ignition device.

  Furthermore, in recent years, in order to improve the mixing of fuel and compressed air, the swirl ratio has been increased, or strong tumble vortices have been generated in the combustion chamber by means of supercharger mixing. Gas fluidization is achieved. For this reason, in the conventional plasma ignition device, flame nuclei injected into the combustion chamber are blown away by a strong in-cylinder airflow, and energy is lost before growing into flame nuclei large enough for ignition, making it difficult to ignite. There is a risk that ignition of the engine will be more difficult.

  Therefore, in view of such circumstances, the present invention injects a plasma gas into an engine combustion chamber of a non-ignitable engine such as a lean homogeneous fuel engine, a lean stratified combustion engine, a supercharged mixed combustion engine, etc. to ignite the engine. An object of the present invention is to provide a plasma ignition device that promotes the growth of flame nuclei and has excellent ignitability.

  In the first invention, a long-axis center electrode, an insulator formed in a substantially cylindrical shape covering the center electrode and extending below the lower end surface thereof, and covering the insulator, A discharge space is partitioned by a ground electrode provided with a ground electrode opening that communicates with the opening, and a high voltage from a discharge power source and a large current from a plasma energy supply power source are supplied to the discharge space. In the plasma ignition device for performing the ignition of the engine by injecting the gas in the discharge space into a high-temperature and high-pressure plasma state and injecting the gas into the engine combustion chamber, the flow of the gas in the plasma state ejected from the discharge space Eddy current forming means for forming a plurality of eddy currents having different moving speeds from the outer periphery toward the center (Claim 1).

  More specifically, as in the second aspect of the invention, the vortex forming means extends to the tip side of the ground electrode and is larger than the opening diameter of the opening so as to cover the periphery of the opening. An eddy current forming space is formed by being partitioned by a substantially cylindrical peripheral wall portion having an opening diameter and protruding partially at different heights toward the combustion chamber.

  Further, as in the third invention, the peripheral wall portion defining the eddy current forming space includes a long wall portion having a long projecting length to the combustion chamber, and a short wall portion having a short projecting length to the combustion chamber. And may be formed in an oblique cylindrical shape in which the height of the inner circumference of the long wall portion and the height of the inner circumference of the short wall portion change continuously (Claim 3).

  Further, as in the fourth aspect of the invention, the peripheral wall portion that divides the eddy current forming space includes a long wall portion having a long projecting length to the combustion chamber and a short wall portion having a short projecting length to the combustion chamber. And may have a notched cylindrical shape in which the height of the inner circumference of the long wall portion and the height of the inner circumference of the short wall portion change intermittently.

  Further, as in the fifth invention, the peripheral wall portion that divides the eddy current forming space includes two or more long wall portions arranged at positions symmetrical with respect to the central axis, and a position symmetrical with respect to the central axis. You may form in the symmetrical form which has the said 2 or more said short wall part arrange | positioned to (Claim 5).

  In a sixth aspect of the invention, supply of a large current from the plasma energy generation power source is divided into a plurality of times by a pulse current in response to one high voltage application from the discharge power source. Item 6).

When a high voltage is applied from the discharge power source, the insulation between the lower end surface of the center electrode and the ground electrode opening is broken, and creeping discharge occurs over the inner peripheral wall surface of the insulator.
A large current flows from the plasma energy supply power source triggered by this creeping discharge, high energy electrons are emitted around the discharge path in the discharge space, gas in the discharge space is ionized, and high temperature and high pressure It becomes a plasma state and is ejected from the discharge space.
At this time, according to the present inventors' earnest test, a plurality of eddy currents having different velocities are formed inside the jet flow by the vortex forming means with respect to the plasma jet jetted from the discharge space (hereinafter referred to as variable speed vortex flow). found.
This speed change vortex forms a vortex ring (hereinafter referred to as a speed change vortex ring) as a whole jet, and encloses the high-plasma energy inside and moves the mixture in the combustion chamber while rotating while moving in the combustion chamber. Combustion grows while taking inside.
In addition, the vortex ring is disturbed by the speed distribution existing in the transmission vortex ring, and the intake of the air-fuel mixture is further improved.
Therefore, by using the plasma ignition device of the present invention, it becomes possible to efficiently use the high energy of the short-lived plasma, and a highly supercharged combustion engine in which a strong in-cylinder airflow exists in the combustion chamber or In addition, ignition of a hardly ignitable combustion engine such as an extremely lean combustion engine can be realized stably.

According to the second invention, the high-temperature and high-pressure plasma jet ejected from the discharge space expands in the outer diameter direction in the vortex formation space partitioned in the peripheral wall portion, and then collides with the inner peripheral wall of the peripheral wall portion. The difference between the velocity at the central portion of the plasma state gas ejected from the discharge space and the velocity in the vicinity of the inner peripheral wall of the peripheral wall portion becomes large, and a vortex flow from the inside toward the outside is generated in the plasma jet.
When the plasma jet is ejected from the peripheral wall portion by the inventors' earnest test, the long wall portion side becomes a leading vortex with a fast moving speed, and the short wall portion side becomes a succeeding vortex with a slow moving speed, It was found that a variable speed vortex ring in which vortices of different speeds exist inside the vortex ring, and this reacts with the air-fuel mixture in the combustion chamber to generate flame nuclei with a high combustion speed.
Therefore, according to the present invention, it is possible to realize a plasma ignition device that generates the above-described variable speed vortex ring to improve the combustion speed and exhibits excellent ignitability.

According to the third invention, the peripheral wall portion is continuously high from the height of the inner periphery of the long wall portion on the side of the long wall portion having a long protruding length to the height of the inner periphery of the short wall portion on the side of the short wall portion having a short protruding length. Since the contact time between the plasma jet ejected from the discharge space and the inner wall of the long wall is different from the contact time of the inner wall of the short wall, the velocity distribution is generated in the vortex. To do.
Therefore, according to the present invention, it is possible to realize a plasma ignition device that generates the above-described variable speed vortex ring to improve the combustion speed and exhibits excellent ignitability.

According to a fourth aspect of the invention, the peripheral wall portion defining the transmission eddy current forming space has a long wall portion having a long projecting length into the combustion chamber and a short wall portion having a short projecting length into the combustion chamber. In addition, since the height of the inner circumference of the long wall portion and the height of the inner circumference of the short wall portion are intermittently formed, the contact time between the plasma jet ejected from the discharge space and the inner circumferential wall of the long wall portion is Different from the contact time with the inner wall of the short wall, a velocity distribution is generated in the vortex.
Therefore, according to the present invention, it is possible to realize a plasma ignition device that generates the above-described variable speed vortex ring to improve the combustion speed and exhibits excellent ignitability.

According to the fifth aspect, since the growth direction of the flame kernel spreads symmetrically, the straightness when the variable speed vortex ring moves in the combustion chamber is improved, and the penetration force is increased.
Therefore, even when a strong in-cylinder airflow is generated in the combustion chamber, the flame can reach a desired position in the combustion chamber, and more stable ignition can be expected.

According to the sixth aspect of the present invention, the shift eddy current following the shift vortex is generated in a superimposed manner by supplying high energy to the plasma ignition plug in a plurality of ways, and the shift vortex flows by colliding with each other. It has been clarified by the present inventors that the turbulence of the gas is further increased, the reactivity with the air-fuel mixture is improved, and a plasma ignition device with a higher combustion speed can be realized.
In addition, since the input energy per one time becomes small, it can be expected that consumption of the center electrode and the ground electrode is suppressed.

1 is an overall view showing a configuration of a plasma ignition device according to a first embodiment of the present invention. (A) is the equivalent circuit schematic which shows the outline | summary of the plasma ignition apparatus in the 1st Embodiment of this invention, (b) is the electric current characteristic diagram. (A) is another equivalent circuit diagram applicable to the plasma ignition device in the 1st Embodiment of this invention, (b) is the electric current characteristic diagram. The operation of the plasma ignition device in the first embodiment of the present invention is shown, (a) is a schematic cross-sectional view of the main part showing a state immediately after the ignition signal is transmitted, (b) is 0.2 ms after ignition The principal part cross-sectional schematic diagram which shows the state. The schlieren photograph substitute for drawing which shows change with time of combustion growth of a flame kernel in order of (a) to (f) in a 1st embodiment of the present invention. The schlieren photograph substitute for drawing which shows the time-dependent change of the combustion growth of the flame kernel in the 2nd Embodiment of this invention in order from (a) to (f). The schlieren photograph which substitutes for drawing which shows the time-dependent change of the combustion growth of the flame kernel in a comparative example in order from (a) to (f). The characteristic view which shows the effect of this invention with respect to the combustion growth of a flame kernel with a comparative example. The characteristic view which shows the effect of this invention with respect to a combustion fluctuation | variation (COV IMEP) with a comparative example. The outline | summary of the plasma ignition apparatus in the 3rd Embodiment of this invention is shown, (a) is principal part sectional drawing, (b) is a principal part bottom surface perspective view, (c) is a model which shows the state of a transmission vortex ring Figure.

  The present invention provides a plasma igniter that applies high energy to a gas in a discharge space to form a high-temperature and high-pressure plasma state and ignites it by injecting it into an engine combustion chamber. It generates moderate turbulence in the nuclei to increase the reactivity with the air-fuel mixture, accelerates the combustion speed of the flame nuclei, such as combustion engines such as automobile engines, especially ultra lean combustion engines, high supercharged mixing engines, etc. It is a plasma ignition device that exhibits excellent ignitability for ignition with difficulty ignition.

A plasma ignition device 1 according to a first embodiment of the present invention will be described with reference to FIG. In the present embodiment, the plasma ignition device 1 includes an ignition plug 10, a discharge power source 20 that applies a high voltage to the spark plug 10, and a plasma energy supply power source 30 that supplies a large current. A tip is exposed in the combustion chamber 400 mounted on the engine 40 (not shown).
The spark plug 10 includes a long-axis center electrode 110, a substantially cylindrical insulator 120 that covers and holds the outer periphery of the center electrode 110, and a substantially cylindrical ground electrode 130 that covers the insulator 120. Yes.

  The center electrode 110 is made of a material having high heat resistance and good electrical conductivity, and a central electrode central shaft 111 made of a material having good electrical conductivity and good heat conductivity is formed on the proximal end side of the center electrode 110, and A central electrode terminal portion 112 connected to the discharge power source 20 and the plasma energy supply power source 30 is formed at the base end.

The insulator 120 is made of high-purity alumina or the like excellent in heat resistance, mechanical strength, high-temperature dielectric strength, thermal conductivity, and the like, and is formed in a cylindrical shape that extends downward from the lower end surface of the center electrode 110. .
An insulator locking portion 121 having a large diameter is formed in the middle of the insulator 120, and the inside of the housing portion 13 is interposed via a seal member (not shown) that maintains airtightness with the housing portion 13 described later. It is locked to.
On the base end side of the insulator 120, a corrugated insulator head 123 is formed that insulates the center electrode terminal portion 112 and the surface of the housing portion 13 and prevents high-voltage leakage.

The ground electrode 130 is made of a conductive metal material, is formed in a substantially cylindrical shape so as to cover the insulator 120, bends toward the center on the tip side, covers the bottom of the insulator 120, and opens at the lower end of the insulator 120. An opening 131 is formed in communication with. A discharge space 140 having a predetermined volume with an inner diameter φD ₁ and a length L ₁ is defined by the inner peripheral wall of the insulator 120, the bottom surface of the center electrode 110, and the opening 131.
The ground electrode 130 has an opening diameter φD ₂ larger than the opening diameter φD ₁ of the opening 131 so as to cover the periphery of the opening 131 as a vortex forming means that is a main part of the present invention, and is directed toward the tip side. Thus, a substantially cylindrical peripheral wall portion (shroud) 15 projecting at a partially different height is formed.
In the present embodiment, the shroud 15 extends from the height L ₂₁ of the long wall inner periphery 151 on the long wall portion 150 side with the long protruding length to the height L ₂₂ of the short wall inner periphery 153 on the short wall portion 152 side with the short protruding length. It is formed in an oblique cylindrical shape so that its height continuously changes, and a variable speed vortex forming space 141 is defined inside thereof.

The outer peripheral portion of the ground electrode 130 extends in a cylindrical shape toward the proximal end so as to cover the outer periphery of the insulator 120, and a back electrode portion 134 that is opposed to the center electrode 110 through the insulator 120 is extended. .
Further, the base end side of the back electrode 134 is fixed to the engine combustion chamber wall surface 40 (not shown) so that the second opening 133 is exposed in the engine combustion chamber 400 (not shown) while holding the insulator 120. At the same time, a housing portion 13 for electrically grounding the ground electrode 130 and the combustion chamber wall surface 40 is formed.
A screw part 135 for screwing to the combustion chamber wall surface is formed on the outer periphery of the back electrode part 134, and a hexagonal part 136 for tightening the screw part 135 is formed on the outer peripheral part on the proximal end side of the housing part 13. Further, a caulking portion 137 is formed for caulking and fixing the insulator 120 in the housing portion 13.

FIG. 2 shows an example of a high energy power source that can be used as a plasma energy generating power source that can be applied to the plasma ignition device 1 according to the first embodiment of the present invention.
The discharge power source 20 includes a first power source 21, an ignition key 22, an ignition coil 23, an ignition coil drive circuit 24, an electronic control device 25, a first rectifier element 26, and an ignition noise absorption resistor 27.
The discharge power source 20 is desirably rectified by the first rectifying element 26 so that the center electrode 110 becomes an anode in order to suppress electrode consumption.

  The plasma generating power source 30 includes a second power source 31, a charging current adjusting resistor 32, a second rectifying element 34, and a plasma energy charging capacitor 33. In order to suppress electrode consumption, the plasma generating power source 30 is desirably rectified by the second rectifying element 34 so that the center electrode 110 becomes an anode.

When a high voltage is applied from the discharge power supply 20 and a breakdown discharge that breaks the insulation in the discharge space 140 occurs, the energy stored in the plasma energy charging capacitor 33 becomes a large current IP and an extremely short discharge time TP. It is released at a stretch. In FIG. 2 (b), at this time, illustrating the relationship between the energy to be introduced and the discharge current IP and the discharge time T _P.

FIG. 3 shows an example of a high energy power source applicable to the plasma ignition device 1 in the second embodiment of the present invention.
As shown in FIG. 3A, in the plasma ignition device 1a according to the second embodiment, a plurality of choke coils 35 and capacitors 33 are provided in parallel with the plasma energy charging capacitor 33, so that FIG. As shown in FIG. 5, in one ignition, the same amount of energy as that released at one time can be supplied as a pulse current divided into two or more peaks.
The choke coil 35 has a low inductance on the downstream side and a high inductance on the upstream side. The breakdown in the discharge space 140 is broken by the breakdown discharge from the discharge power source 20, and first, a first stage of large current is discharged from the capacitor 33 in which the choke coil 35 is not interposed. The second-stage current is released from the capacitor 33 delayed by the choke coil 35, and further, the third-stage current is released from the capacitor 33 delayed by the high-inductance choke coil 35.

The effects of the present invention will be described with reference to FIGS.
When a high voltage is applied from the discharge power supply 20, the insulation between the lower end surface of the center electrode 110 and the ground electrode opening 131 is broken, and creeping discharge occurs so as to cover the inner peripheral wall surface of the insulator 120.
With this creeping discharge as a trigger, a large current flows from the plasma energy supply power source 30, high energy electrons are emitted around the discharge path in the discharge space 140, gas in the discharge space 140 is ionized, and high temperature / high pressure It becomes a plasma state and is ejected from the discharge space 140.

At this time, as shown in FIG. 4A, the plasma jet PZ ejected from the discharge space 140 expands in the outer diameter direction in the variable speed vortex formation space 141 and then collides with the inner peripheral wall of the shroud 15. The difference between the velocity at the center of the gas in the plasma state ejected from the gas and the velocity in the vicinity of the inner peripheral wall of the shroud 15 becomes large, and a vortex flowing from the inside toward the outside is generated in the plasma jet PZ.
Furthermore, the shroud 15 is continuously from a height L ₂₁ of longwall inner peripheral 151 in a long long wall portion 150 side of the protruding length to the height L ₂₂ of the minor wall portion inner peripheral 153 in a short minor wall portion 152 side of the projecting length Since the contact time between the ionized gas ejected from the discharge space 140 and the long wall inner peripheral wall 151 is different from the contact time between the short wall inner peripheral wall 153 and the vortex flow. Velocity distribution occurs.
As shown in FIG. 4 (b), when the plasma jet PZ is ejected from the shroud 15, the long wall 150 side becomes the leading vortex VR _{1 having} a high moving speed, and the short wall 152 side moves. The subsequent vortex VR ₂ having a low velocity forms a variable velocity vortex ring (V _VVR ) in which vortices having different velocities exist inside one vortex ring, which reacts with the air-fuel mixture in the combustion chamber 400. As a result, it was found that a flame kernel with a high burning rate was generated.
Since the plasma energy is confined in the rotating variable vortex ring V _VVR , it is possible to maintain the high energy state of the plasma longer than in the conventional plasma ignition device.
In addition, the preceding vortex VR ₁ having a fast moving speed and the succeeding vortex VR ₂ having a slow moving speed form an integrated variable speed vortex ring V _VVR to burn while growing the flame kernel while taking in the air-fuel mixture in the combustion chamber 400. Since it moves in the chamber 400, it is presumed that the shift vortex ring V _VVR is moderately disturbed due to the deviation of the rotational speed of the vortex, the air-fuel mixture is taken into the shift vortex ring V _VVR , and the combustion speed is increased. .

In order to confirm the effect of the present invention, a combustion test was conducted using a combustion test vessel in which propane and compressed air were introduced at a predetermined mixing ratio and the inside was adjusted to a predetermined pressure, imitating a lean combustion engine. A Schlieren image was taken every 0.2 ms from the start of ignition.
The plasma ignition device 1 according to the first embodiment of the present invention was mounted, and 200 mJ of energy was supplied at a time as shown in FIG.
As shown in FIG. 3, energy of 200 mJ was supplied in two portions, which was referred to as Example 2.
Further, using a conventional plasma spark plug in which the shroud 150 of the present invention is not formed as in Patent Document 1, energy of 200 mJ was supplied as shown in FIG.
In this test, specifically, as Example 1 and Example 2, φD ₁ = 1.3 mm, φD ₂ = 3.0 mm, L ₁ = 1.3 mm, L ₂₁ = 1 mm, L ₂₂ = using those set 2 mm, in Comparative example 1 was used [phi] D ₁ = 1.3 mm, those that have been set to [phi] D ₂ = 3.0 mm.
Part of the test results of Example 1, Example 2, and Comparative Example 1 are shown in FIGS. 5, 6, and 7, respectively.

5A to 5F, the plasma flame ejected from the discharge space 140 moves in the combustion chamber while rotating while forming a vortex ring in Example 1 of the present invention. The movement speed of the vortex on the short wall 152 side is slower than the movement speed of the vortex on the long wall section 150 side of the shroud 15, and the vortex ring is turbulent. It was confirmed that it grew.
Further, as shown in order in the order of time in FIGS. 6A to 6F, in Example 2 of the present invention, a larger disturbance occurs in the flame kernel than in Example 1, and the rate of flame growth is faster. It was confirmed that the flame grew to a larger flame than Example 1.
On the other hand, as shown in the order of time in FIGS. 7A to 7F, in the case of using the conventional plasma ignition device, in Comparative Example 1, the flame kernel injected from the discharge space has a substantially spherical shape. It was confirmed that the flame nuclei were uniformly grown without being disturbed, but the moving distance in the combustion chamber was shorter than that in Examples 1 and 2.

Furthermore, in order to confirm the effect of the present invention on the growth rate of flame nuclei, the schlieren photographs of Example 1, Example 2 and Comparative Example 1 shown in FIGS. The cross-sectional area was calculated, the change with time was measured, and the result is shown in FIG.
As shown in FIG. 8, although the sizes of flame nuclei injected immediately after ignition of Examples 1, 2 and Comparative Example 1 of the present invention are almost the same, Example 1 and Example Both were grown larger than Comparative Example 1, and according to the present invention, it was found that the growth rate of flame nuclei was faster than that of the conventional plasma ignition device.

  Further, in the actual internal combustion engine (2000 rpm, air-fuel ratio 26.2) using the plasma ignition device 1 in the first embodiment of the present invention, the plasma ignition device 1a in the second embodiment, and the conventional plasma ignition device. The result of the measured combustion fluctuation (COV IMEP%) is shown in FIG. As shown in this figure, according to the present invention, it has been found that combustion fluctuation can be reduced.

As shown in FIGS. 10A and 10B, in the plasma ignition device according to the third embodiment of the present invention, in addition to the same configuration as that of the above-described embodiment, the shape of the shroud 15a is changed to one of the peripheral walls of the shroud 15a. The two or more long wall portions 150a and the short wall portions 151a are intermittently changed, and are formed in a symmetrical shape so as to be respectively targeted with respect to the central axis. By forming the shroud 15a in such a shape, a symmetrical transmission vortex ring V _VVR a in which the leading vortex VR ₁ a and the trailing vortex VR ₂ a are orthogonal as shown in FIG. 10C is formed.
Since the growth direction of the flame kernel spreads symmetrically, the straightness when the variable speed vortex ring V _VVR a moves in the combustion chamber 500 is improved, and the penetration force is increased. Therefore, even when a strong in-cylinder airflow is generated in the combustion chamber 400, the flame can reach a desired position in the combustion chamber 400, and more stable ignition can be expected.

The present invention is not limited to the above-described embodiment, and the shape of the specific rotation imparting mechanism is determined according to the size of the engine to be applied, the type of fuel, and the operating state of the engine without departing from the spirit of the present invention. Can be appropriately changed. For example, in the above-described embodiment, the plasma type plasma ignition device constituted by one ignition plug has been described. However, the present invention can be applied to a multi-cylinder engine including a large number of ignition plugs.
Further, in the above embodiment, the case where the high voltage power source is constituted by the two power sources of the discharge power source 20 and the plasma generating power source 30 has been described. It is good also as a structure adjusted and used as the power supply for discharge and the power supply for plasma generation. Further, in the above-described embodiment, the case where a normal ignition coil is used as the boosting circuit of the discharge power source has been described as an example, but a capacitor discharge ignition coil (CDI), a piezoelectric transformer, or the like is used. May be.

DESCRIPTION OF SYMBOLS 1 Plasma ignition apparatus 10 Spark plug 110 Center electrode 120 Insulator 130 Ground electrode 140 Discharge space 141 Variable eddy current formation space 15 Shroud (peripheral wall part, eddy current formation means)
150 Long wall portion 151 Long wall portion inner circumference 152 Short wall portion 153 Short wall portion inner circumference 20 Discharge power source 30 Plasma energy supply power source 40 Internal combustion engine 400 Engine combustion chamber φD ₁ Discharge space inner diameter (insulator inner wall inner diameter)
φD ₂ Shroud inner diameter L ₁ Discharge space length L ₂₁ Long wall inner circumferential height L ₂₂ Short wall inner circumferential height VR ₁ Leading vortex VR ₂ Successive vortex V _VVR variable vortex ring

JP 2006-294257 A

Claims (6)

A long-axis center electrode, an insulator formed in a substantially cylindrical shape that covers the center electrode and extends below the lower end surface thereof, and a ground that covers the insulator and communicates with the opening of the insulator The discharge space is partitioned by a ground electrode provided with an electrode opening,
A high voltage is applied from the discharge power source to the discharge space and a large current is supplied from the plasma energy supply power source, and the gas in the discharge space is changed to a high-temperature and high-pressure plasma state to cause engine combustion. In a plasma ignition device that ignites the engine by injecting into the room,
A plasma igniter comprising a vortex forming means for forming a plurality of vortexes having different moving speeds from the outer periphery toward the center of the gas flow in a plasma state ejected from the discharge space.   The eddy current forming means extends to the front end side of the ground electrode, has an opening diameter larger than the opening diameter of the opening so as to cover the periphery of the opening, and partially enters the combustion chamber. 2. The plasma ignition device according to claim 1, wherein a vortex forming space is formed by being partitioned by a substantially cylindrical peripheral wall projecting at different heights. The peripheral wall portion that divides the vortex forming space has a long wall portion with a long protruding length into the combustion chamber and a short wall portion with a short protruding length into the combustion chamber,
3. The plasma ignition device according to claim 2, wherein the inner circumference of the long wall portion and the inner circumference of the short wall portion are formed in an oblique cylindrical shape in which the height continuously changes. The peripheral wall portion that divides the vortex forming space has a long wall portion with a long protruding length into the combustion chamber and a short wall portion with a short protruding length into the combustion chamber,
3. The plasma ignition device according to claim 2, wherein the plasma ignition device is formed in a notched cylindrical shape in which the height of the inner circumference of the long wall portion and the height of the inner circumference of the short wall portion change intermittently.   The peripheral wall portion that divides the eddy current forming space includes two or more long wall portions that are disposed symmetrically with respect to the central axis, and two or more short walls that are disposed symmetrically with respect to the central axis. The plasma ignition device according to claim 3, wherein the plasma ignition device is formed in a symmetrical shape having a portion.   2. The supply of a large current from the plasma energy generating power source is divided into a plurality of times by a pulse current in response to one high voltage application from the discharge power source. 6. The plasma ignition device according to any one of items 5 to 5.