JP2009030593A - Plasma ignition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition system easy to install and excelling in an effect of preventing leakage of electromagnetic wave noise. <P>SOLUTION: The plasma ignition system 1 includes an ignition plug 10 attached to an internal combustion engine and having a discharge space 140 formed between a center electrode 110 and an earth electrode 130, electric power sources 30, 40, a discharge power source circuit 300, and a plasma generation power source circuit 400. In the ignition system, at least a resistance element 37 and a rectifier element 43 for rectifying plasma current are placed in an element receiving portion 2 provided near a center electrode terminal part 111 as close as possible in a plug hole 52, and distances L<SB>1</SB>, L<SB>2</SB>between the resistance element 37 and the rectifier element 43, and the center electrode terminal part are made as short as possible, for instance equal to or smaller than 30 cm, so that transmission of the electromagnetic wave noise can be effectively inhibited. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a measure for preventing leakage of electromagnetic noise in a plasma ignition device used for ignition of an internal combustion engine.

  In recent years, from the viewpoint of environmental protection, in order to reduce emissions in combustion exhaust gas and improve fuel efficiency, lean mixed combustion, supercharged mixed combustion, and the like are required in internal combustion engines, and ignition conditions have become severe. Therefore, there is a demand for an ignition device that can achieve stable ignition even in an internal combustion engine that is difficult to ignite.

In ignition of an internal combustion engine, an ignition device using a normal spark plug 10z as shown in FIG. 12A includes a battery 31z, an ignition switch 32z, an ignition coil 33z, an electronic control unit (ECU) 35z, and an ignition coil drive circuit. (Transistor) 34z, a rectifying element 21z, and a spark plug 10z.
As shown in FIG. 12B, the ignition switch 32z is turned on, and a low voltage primary voltage is applied from the battery 31z to the primary coil 331z of the ignition coil 33z by the ignition signal from the ECU 35z, and then the ignition coil drive circuit When the primary voltage is cut off by switching of 34z, the magnetic field in the ignition coil 33z changes, a secondary voltage of -10 to -30 kV is generated in the secondary coil 332z of the ignition coil 33z, and the center electrode 110z and the ground electrode 131z. Discharge occurs and occurs in a narrow high temperature range. In the normal ignition by the spark plug 10z, this high temperature region serves as an ignition source to excite the ignition explosion of the compressed mixture.
At this time, the current rectified by the diode 21z flows to the secondary coil 332z in a relatively long discharge period of about 2 ms, and about 35 mJ of energy is released to the spark plug 10z.

On the other hand, in the ignition by the plasma ignition device 1x as shown in FIG. 11A, when the ignition switch 31x is turned on as shown in FIG. 11B, the primary voltage from the discharge battery 30x is low. Is applied to the primary coil 321 of the ignition coil 32x, the primary voltage is cut off by switching of the ignition coil drive circuit (transistor) 33x controlled by the electronic control unit (ECU) 34x, and the magnetic field in the ignition coil 32x changes, A secondary voltage of −10 to −30xV is generated in the secondary coil 322x of the ignition coil 32x, and this secondary voltage is discharged into the discharge gap 141x in the discharge space 140x formed between the center electrode 110x and the ground electrode 130x. When a discharge voltage proportional to is reached, the insulation in the discharge space 140x is broken and discharge is started.
Simultaneously with the discharge, the energy (for example, −450 V, 120 A) stored in the capacitor 42x from the plasma energy supply battery 40x provided separately from the discharge battery 30x is released into the discharge space 140x at once, Since the gas is in a high-temperature and high-pressure plasma state and is ejected from the opening 132x provided at the tip of the discharge space 140x, it is rich in directivity and has an extremely high temperature range of several thousand to several tens of thousands of degrees in a large volume range. Will occur.
Therefore, such a plasma ignition device is expected to be applied to an ignition device in a low-ignition internal combustion engine such as lean mixed combustion or supercharged mixed combustion.
Further, when such a plasma ignition device is applied to a normal spark plug, high energy plasma is generated between the electrodes of the plug, so that improvement in ignitability can be expected.

However, in the conventional plasma ignition device 1x, the energy stored in the plasma generating capacitor 42x is instantaneously supplied to the plasma ignition plug 10x, so that it is as short as about 8 μsec as shown in FIG. A large current of about 120 A flows during the discharge period. Since this is periodically repeated according to the rotation of the engine, high-frequency electromagnetic noise is generated.
Such electromagnetic noise may cause malfunction of an electronic control device mounted on the vehicle and may cause engine misfire.
As a method for preventing such electromagnetic wave noise, Patent Document 1 discloses that a shield wire is used for a plasma generation wiring connecting a plasma generation power source and a plug, an electromagnetic wave shield is provided so as to cover the entire plug, and a discharge power source and A method of blocking electromagnetic wave noise by using a resistance wire for a discharge wiring connecting a plug is disclosed.

Japanese Utility Model Publication No. 55-172659

However, an internal combustion engine such as an automobile engine is usually composed of a plurality of cylinders, and the conventional method as disclosed in Patent Document 1 needs to provide electromagnetic shielding over a very wide range.
In a plasma ignition device in which a plurality of plasma ignition plugs 10x (1), 10x (2), 10x (3), 10x (4) as shown in FIG. 10 are connected to an ignition coil 32x via a distributor 60x, In order to suppress the generation of electromagnetic noise, when a shield wire is used for the plasma generation wiring 400x connected to each plug, the entire plug is covered with an electromagnetic shield, and a resistance wire 36x is used for the high voltage supply wiring, Since the lengths are different, the stray capacitance Cs (1-6) of each electromagnetic wave shield part Sd (1-6) is not constant.
For this reason, it becomes difficult to maintain the ground potential of each electromagnetic wave shield part at the same electric potential, and a potential difference is generated between the electromagnetic wave shields.
Such a potential difference becomes a new source of electromagnetic wave noise, and electric field concentration occurs at the connection portion of each electromagnetic wave shield part, making it difficult to completely block electromagnetic wave noise.

In addition, a transmission circuit is formed by the ignition coil 32x and the plasma ignition plug 10x as a discharge field, and electromagnetic noise is generated when a high voltage is applied from the ignition coil 32x to start discharge, and the center electrode terminal portion 112x The plasma generation wiring connecting the plasma generation capacitor 42x may become an antenna and leak to the outside.
In a normal spark plug, a resistance element is interposed between the ignition coil and the plug to prevent such electromagnetic noise from being transmitted.
However, since a large current must flow through the plasma generation wiring as described above, it is not possible to absorb electromagnetic wave noise at the start of discharge by interposing a resistance element on the plasma generation wiring.

  Therefore, in view of such circumstances, the present invention provides a plasma ignition device that is easy to mount and excellent in the effect of preventing the inevitable generation of electromagnetic noise generated to the outside. It is the purpose.

  According to the first aspect of the present invention, an ignition plug mounted on the internal combustion engine, a discharge power supply circuit, and a plasma generation power supply circuit are provided, and a high voltage is applied from the discharge power supply circuit and the plasma generation is performed. Plasma ignition for igniting the internal combustion engine by applying a large current from the power supply circuit to bring the gas in the discharge space formed between the center electrode and the ground electrode of the spark plug into a high-temperature and high-pressure plasma state. In the apparatus, a resistance element is interposed between the discharge power supply circuit and the center electrode, a rectifier element is interposed between the plasma generation power circuit and the center electrode, and the resistance element The rectifying element is placed in an element housing provided around the center electrode.

According to the first aspect of the present invention, the electromagnetic noise generated in the discharge power supply circuit and conducted through the distribution line from the discharge power supply circuit to the ignition plug is converted into heat by the resistance element and absorbed. Can do.
In addition, since the current flowing from the discharge power supply circuit is suppressed by the resistance element and the current change is reduced, the generation of electromagnetic noise can be suppressed.
Furthermore, since discharge is a high-frequency phenomenon that occurs instantaneously, electromagnetic noise generated due to current changes that occur during discharge can be absorbed quickly by placing the resistive element at a position close to the discharge part. The electromagnetic noise reduction effect is increased. Further, since the change in current is smaller than that in the resistance element and the change in magnetic field is also reduced, electromagnetic noise itself can be reduced.
In addition, by placing the resistance element in an element housing provided around the center electrode, a stray capacitance formed between the electric wire from the discharge voltage power source to the center electrode and the ground. The generated electromagnetic wave noise can be absorbed efficiently. The stray capacitance flows instantaneously and the current change is large, causing electromagnetic noise. If a resistor is inserted, the current change due to the stray capacitance can be suppressed and the electromagnetic noise itself can be reduced.
Furthermore, when the plasma current is emitted, the rectifying element is reverse-biased and functions as a noise absorbing capacitor, and electromagnetic noise can be further reduced.
Therefore, it is possible to realize extremely stable ignition of a hardly ignitable internal combustion engine by the plasma ignition device excellent in the effect of preventing the emission of electromagnetic noise to the outside.

Specifically, as in the invention of claim 2, setting the lower end of the resistive element a distance L ₁ to the upper end of the center electrode to 30cm or less.

It has been found that electromagnetic noise can be reduced most effectively by disposing the resistance element within the scope of the invention of claim 2. Therefore, the ignition by the plasma ignition device can be further stabilized in the hardly ignitable internal combustion engine.

Also, as in the invention of claim 3, setting the distance L ₂ from the lower end of the rectifier element to the upper end of the center electrode to 30cm or less.

It has been found that the electromagnetic noise can be further effectively reduced by disposing the flow rectifying element within the scope of the invention of claim 3. Therefore, the ignition by the plasma ignition device can be further stabilized in the hardly ignitable internal combustion engine.

Furthermore, as in the invention of claim 4, the total distance between the distance L ₂ from the lower end of the distance L ₁ and the rectifying element from the lower end of the resistive element to the upper end of the center electrode to the upper end of the center electrode (L ₁ + L ₂ ) is desirably set to 30 cm or less.

According to the invention of claim 4, it has been found that the electromagnetic noise is further reduced. Therefore, the ignition by the plasma ignition device can be further stabilized in the hardly ignitable internal combustion engine.

According to a fifth aspect of the present invention, the resistance element and the rectifying element are arranged side by side above the center electrode.

  According to the invention of claim 5, the geometric distance between the resistance element and the center electrode terminal portion and the geometric distance between the rectifying element for rectifying the plasma current and the center electrode terminal portion can be minimized. Furthermore, it can be expected to reduce electromagnetic noise.

According to a sixth aspect of the present invention, a part or all of the element storage portion is placed in a plug hole provided in an engine block of the internal combustion engine.

According to the invention of claim 6, the plug hole acts as an electromagnetic shield and can absorb electromagnetic noise.

  According to a seventh aspect of the invention, the element storage portion is provided so as to close the opening of the plug hole.

  According to the seventh aspect of the present invention, it is difficult for electromagnetic noise to be radiated from the plug hole to the outside, and the electromagnetic noise can be more reliably reduced.

  According to an eighth aspect of the present invention, the element housing portion includes a radio wave absorbing member made of a metal material or a magnetic material.

  According to the invention of claim 8, even when the plug hole is formed by a member having a low effect as an electromagnetic shield, the element housing portion is covered with a metal material or mixed with a magnetic material. Thus, the element housing itself functions as an electromagnetic shield and can absorb electromagnetic noise.

  According to a ninth aspect of the present invention, the plasma generating power supply circuit includes a plurality of capacitors charged by a power source, and a part or all of the capacitors are placed in the element housing portion.

According to the ninth aspect of the present invention, a part of the capacitor acts as a noise absorbing capacitor without attenuation of the discharge voltage, and only the high-frequency noise current generated at the time of discharge is bypassed with the element housing portion as the ground. Thus, it is possible to prevent electromagnetic wave noise generated when plasma current is emitted from being transmitted to the outside of the element housing portion. In addition, since the large current supply line connecting the capacitor and the center electrode can be extremely shortened, the large current supply line does not serve as an antenna, and transmission of electromagnetic noise can be prevented.
Therefore, stable ignition by the plasma ignition device can be realized in a hardly ignitable internal combustion engine.

  According to a tenth aspect of the present invention, the discharge power supply circuit includes boosting means for boosting the power supply voltage and a rectifying element for rectifying the discharge current, and the rectifying element is placed in the element housing portion.

According to the invention of claim 10, at the time of discharging, the rectifying element that rectifies the discharge current is reverse-biased and functions as a capacitor, so that electromagnetic wave noise can be further reduced. Therefore, in a hardly ignitable internal combustion engine, ignition by the plasma ignition device can be realized more stably.
Furthermore, by placing the rectifying element for rectifying the discharge current, the rectifying element for rectifying the plasma current, and the plasma generating capacitor in the element housing portion, the plasma ignition plug can be made into an internal combustion engine without increasing the size of the plasma ignition plug. Is easy to mount.
Therefore, stable ignition by the plasma ignition device can be realized in a hardly ignitable internal combustion engine.

  According to an eleventh aspect of the present invention, the discharge power supply circuit includes an ignition coil as the boosting means and an ignition coil drive circuit for driving the ignition coil, and the upper ignition coil is placed in the element housing portion.

  According to the eleventh aspect of the invention, since the high voltage supply line for discharge connecting the ignition coil and the center electrode can be shortened, the high voltage supply line for discharge does not serve as an antenna, and electromagnetic noise is generated outside the element housing portion. Can be prevented from being sent from. By comprehensively storing noise generation sources within a certain range, electromagnetic wave noise can be efficiently contained in the element storage portion. If the ignition coil is housed, the electromagnetic wave noise source and the components connected to the electromagnetic wave noise source can be housed in a compact and integrated manner, and the effect of reducing electromagnetic noise is great. Further, the plasma ignition device can be easily mounted on the internal combustion engine without increasing the size of the plasma ignition device.

  In the invention of claim 12, the resistance value of the resistance element is set to 3 kΩ or more, more preferably 5 kΩ or more.

  It has been found that by setting the resistance value of the resistance element within the scope of the invention of claim 12, generation of electromagnetic noise can be further effectively suppressed.

  According to a thirteenth aspect of the present invention, the ignition coil and a rectifying element that rectifies the discharge current are connected by a resistance wire.

  According to the thirteenth aspect of the present invention, it is possible to absorb the electromagnetic noise generated by the current value change between the ignition coil and the rectifying element that rectifies the discharge current by the resistance wire.

  In the invention of claim 14, the resistance value of the resistance wire is set to 10 to 20 kΩ / m.

  It has been found that the effect of suppressing the generation of electromagnetic noise can be further increased by setting the resistance value of the resistance wire within the scope of the invention of claim 14.

  In the invention of claim 15, the power source and the capacitor are connected by a resistance line, and the capacitor and the center electrode are connected by a resistance-free line.

  According to the invention of claim 15, at the time of discharging, since a large current is supplied from the capacitor to the center electrode through the resistance-free line, the current value of the large current is not reduced, and the power supply Electromagnetic wave noise accompanying charging and discharging repeated between the capacitor and the capacitor can be absorbed by the resistance wire.

  In a sixteenth aspect of the present invention, a resistance value over the entire length of the resistance wire connecting the power source and the capacitor is set to a predetermined value of 1 kΩ or more.

  If the resistance value of the resistance wire is set within the scope of the invention of the sixteenth aspect, electromagnetic wave noise can be effectively absorbed.

  In the invention of claim 17, the variation in resistance value of the resistance wire is within ± 100Ω.

  According to the seventeenth aspect of the present invention, electromagnetic wave noise can be effectively absorbed. Further, when the present invention is applied to an internal combustion engine composed of a plurality of cylinders, the difference between the resistance lines is reduced, thereby reducing the difference in ground potential and preventing the generation of new electromagnetic noise.

A first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the plasma ignition device 1 in this embodiment includes a plasma ignition plug 10, power supplies 30 and 40, a discharge power supply circuit 300, a plasma generation power supply circuit 400, an element storage unit 2, and an electronic control device. 34.

  The discharge power supply circuit 300 is connected to the power supply 30, and is connected to an ignition switch 31, an ignition coil 32, and an ignition coil drive circuit 33 that drives the fire coil 32 by an ignition command from an external electronic control unit ECU 34. The plasma generation power supply circuit 400 includes the element 35 and is connected to the power supply 40, and includes a DC-DC converter 44, a resistor 41, and plasma generation capacitors 42 and 42a.

  The ignition coil drive circuit 33 includes a transistor whose opening and closing is controlled by an electronic control unit (ECU) 34 provided outside. The ignition coil drive circuit 33 boosts the voltage from the power source 30 by the ignition coil 32 to the high-voltage plasma ignition plug 10. The supply is controlled.

The rectifying element 35 that rectifies the discharge current rectifies the high voltage from the ignition coil 32 and prevents the backflow of a large current from the plasma generating capacitor 42.
The ignition coil 32 and the rectifying element 35 that rectifies the discharge current are connected by a high resistance line 36, and the resistance element 37 is connected between the rectifying element 35 that rectifies the discharge current and the center electrode 110. It is placed so as to make the position near the end, that is, the downstream discharge delivery line 370 from the resistance element 37 to the center electrode terminal portion 111 as short as possible.

  The plasma generating capacitor 42 is charged by the power source 40, and discharges a large current to the plasma spark plug 10 during discharging.

  The rectifying element 43 that rectifies the plasma current is placed so as to make the downstream large current delivery line 430 to the center electrode terminal 111 as short as possible, rectifies the large current from the plasma generating capacitor 42, and also an ignition coil. The reverse flow of the discharge voltage from 32 is prevented.

  The plasma ignition plug 10 includes a columnar center electrode 110 made of a conductive metal material, a cylindrical insulating member 120 that insulates and holds the center electrode 110, and a ground electrode 130 made of a cylindrical metal that covers the insulating member 120. Has been.

  The distal end side of the center electrode 110 is formed in a long axis shape by a conductive material such as iridium or an iridium alloy, for example, and the center electrode central shaft made of a metal material having good electrical conductivity and high thermal conductivity such as a steel material or copper inside. The center electrode terminal portion 111 is formed on the base end side.

The ground electrode 130 is formed with a ground electrode opening 131 at the lower end thereof, and a screw portion 132 for being screwed to the engine block 51 at the outer periphery thereof. The insulating member 120 is housed and held at the base end side. A housing portion 135 is formed, and a hexagonal portion 133 for screwing the screw portion 132 is formed on the outer periphery of the housing 135.
The housing 135 including the ground electrode 130 is formed of a metal material such as nickel or iron.

A discharge space 140 is formed inside the insulating member 120, and discharge is possible between the center electrode 110 and the ground electrode 130.
The insulating member 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 an insulating member head 121 is formed on the base end side, and the center electrode terminal portion Electrical insulation between 111 and the housing 135 is ensured.

  The plasma spark plug 10 is mounted in a plug hole 52 provided in the engine block 51 so that the tip is exposed in a combustion chamber 5 formed by an engine block 51 and a cylinder block 53 of an internal combustion engine (not shown). At the same time, the ground electrode 130 is electrically grounded to the engine block 51.

The element storage portion 2 which is a main part of the present invention stores therein a resistance element 37 and a rectifying element 43 that rectifies plasma current as elements, and a discharge power supply circuit 300 and a resistance element upstream of the resistance element 37. 37, a part of the upstream discharge delivery line 371 that connects to 37, the downstream discharge delivery line 370 that connects the resistance element and the common electrode 210 on the downstream side of the resistance element 37, and the rectifying element 43 that rectifies the plasma current. The upstream large current distribution lines 410 and 431 connecting the plasma generating power supply circuit 400 and the rectifying element for rectifying the plasma current on the upstream side, and the rectifying element for rectifying the plasma current on the downstream side of the rectifying element 43 for rectifying the plasma current. 43, the downstream large current distribution line 430 connecting the common electrode 210, the spring electrode 211 connecting the common electrode 210 and the central electrode terminal portion 111, and the epoxy tree covering them. An insulating resin mold 200,201,203 consisting etc., in order to mount the insulating member head portion 130 of the plasma ignition plug 10 is constituted by an insulating portion 205 formed in a tubular shape by an elastic member.
The element storage portion 2 is stored in the plug hole 52 of the engine block 51 so as to substantially close the opening of the plug hole 52.

The downstream discharge delivery line 370, the downstream large current delivery line 430, the common electrode 210, and the spring terminal 211 are between the peripheral wall of the plug hole 52 from the resistance element 37 to the upper end surface of the center electrode terminal portion 111. And the stray capacitance formed between the peripheral wall of the plug hole 52 from the rectifying element 43 that rectifies the plasma current to the upper end surface of the center electrode terminal portion 111 are made as small as possible. The distance L ₁ from the lower end surface of the resistance element 37 to the center electrode terminal portion 111 and the distance L ₂ from the lower end surface of the rectifying element 43 that rectifies the plasma current to the center electrode terminal portion 111 are set as short as possible. desirable.

FIG. 2 shows an outline of the electromagnetic noise measurement method of the plasma ignition device 1 in the present embodiment. As shown in FIG. 2, a noise detection coil (φ82mm, 20T) is provided at a predetermined distance from the plasma ignition device 1, and the maximum width P-Pmax (V) obtained by measuring radio noise 10 times is measured with an oscilloscope. did.
Under the conditions shown in Table 1, the distance L ₁ from the resistance element 37 to the upper end surface of the center electrode terminal portion 111 and the distance L ₂ from the rectifying element 43 that rectifies the plasma current to the upper end surface of the center electrode terminal portion 111 are changed. Measurements were made on the examples and the comparative example in which the resistance element 37 was not interposed. In the drawing, a broken line SLD represents an electromagnetic shield in the embodiment in which almost all the circuits are placed in the plug hole (PH) 52.

FIG. 3 shows the effect of the present invention together with a comparative example.
Example 1, as shown in FIG. 2, houses the all the circuits in the plug hole 52, in the most noise reduction effect embodiment of the present invention to use the engine block 51 as a shield (SLD), L ₂ Is fixed (3 mm) and the noise reduction effect when L ₁ is changed is shown. In FIG. 3, the vertical axis represents the noise level, the horizontal axis represents the total length of L ₁ and L _2.
Example 2, and a rectifying element 43 for rectifying the resistive element 37 and plasma current housed outside the plug hole 52, to secure the L _1, illustrating a noise reduction effect of changing the L _2.
Example 3, a rectifying element 43 for rectifying the resistive element 37 and plasma current housed outside the plug hole 52, to secure the L _2, showing the noise reduction effect of changing the L _1.
Comparative Example 1 shows an electromagnetic wave noise state in a conventional plasma ignition device in which the resistance element 37 is not provided and the discharge power source and the center electrode are connected by a resistance wire.
Comparative Example 2 is a noise generated when L ₂ is fixed and L ₁ is changed in a conventional plasma ignition device that does not include a conventional resistance element and connects a discharge power source and a center electrode by a resistance wire. The reduction effect is shown. The length of L ₁ when there is no resistance element 37 is the distance between the rectifying element 35 that rectifies the discharge current and the center electrode terminal portion 111.
Comparative Example 3 does not include the resistance element 37, and in the conventional plasma ignition device in which the discharge power source and the center electrode are connected by a resistance wire, the noise reduction effect when the entire circuit is placed in the plug hole 52 Indicates.

As shown in FIG. 3, from the results of Example 2 and Example 3, the noise reduction effect when the resistance element 37 and the rectifying element 43 for rectifying the plasma current are placed around the center electrode terminal portion 111 is as follows. Both are substantially equal, and it has been found that electromagnetic noise increases when either L ₁ or L ₂ is longer. Furthermore, it has been found that the noise level can be reduced as the total distance between L ₁ and L ₂ is shortened.
Also, when placing the rectifying device 35 that rectifies a discharge current in the periphery of the center electrode terminal part 111 is also the shorter the distance L ₁ from the rectifying element 35 for rectifying a discharge current to the center electrode terminal part 111, It has been found that the noise reduction effect is increased.
Furthermore, it has been found that electromagnetic noise can be reduced most effectively by accommodating all the elements as much as possible in the element accommodating portion 2 and placing them in the plug holes 52.
Further, the rectifying element 43 for rectifying the resistive element 37 and the plasma current, when placed side by side in the plug hole 52, L ₁ and can shorten the wiring length of L _2, is expected to further noise reduction effect becomes higher .
When a rectifying element 43 for rectifying the resistive element 37 and plasma current placing shifted vertically, geometrically longer than arranged in total length of L ₁ and L _2, made as a result, noise increases risk There is.

By this test, preferably, a distance L ₁ to the top edge of the bottom and the center electrode terminal part 111 of the resistance element 37 is set to 30cm or less, up to the upper end of the rectifying element 43 and the center electrode terminal part 111 that rectifies a plasma current by setting the distance L ₂ to 30cm or less, it has been found capable of reducing effectively electromagnetic noise.
Noise can be reduced by storing the elements in the element storage portion 2 so that the lengths of L ₁ and L ₂ are shortened. At this time, as described above, when the element storage portion 2 is inserted into the plug hole 52, the noise reduction effect is enhanced.

If the engine head 51 that defines the plug hole 52 is made of a shielding material, an effect as an electromagnetic shield can be expected.
When the engine head 51 that defines the plug hole 52 is not made of a shield material, a shield function may be added to the element housing portion 2.
As a material for adding a shielding function to the element housing portion 2, a conductive metal (copper, iron, Ni, Al, etc. and alloys thereof) capable of flowing radiation noise to the ground, or a radio wave absorber (magnetic material, electromagnetic material) Etc.) is desirable.
Also, structurally, these shield materials are applied to the surface of the element storage portion 2 as a film, painted, sandwiched or pasted in a sheet form, or resin / rubber forming the element storage portion It can be mixed with materials such as materials.

  A plasma ignition device 1e according to a second embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment in that the basic configuration is the same, and the connection method between the discharge power supply circuit 300e and the plasma generation power supply circuit 400e is slightly different. In the present embodiment, the secondary coil 322e of the ignition coil 32e is connected to the plasma generating power supply circuit 400e, and the rectifying element 43 that rectifies the plasma current is also used for rectifying the discharge current. Even with such a configuration, the effect of reducing electromagnetic wave noise can be exhibited as in the above embodiment.

  A plasma ignition device 1a according to a third embodiment of the present invention will be described with reference to FIG. The plasma ignition device 1a according to the present embodiment has the same basic configuration as that of the first embodiment, except that the element housing portion 2a is covered with a shield member 204. With such a configuration, the engine block 51 functions as an electromagnetic shield, and electromagnetic wave noise can be efficiently suppressed from being radiated to the outside of the plug hole 52.

  A plasma ignition device 1b according to a fourth embodiment of the present invention will be described with reference to FIG. In addition, since the same code | symbol is attached | subjected about the part which is common in the said embodiment, description is abbreviate | omitted and only the characteristic part of the plasma ignition device 1b in this embodiment is demonstrated. The element storage portion 2b, which is the main part of the present invention, includes an ignition coil drive circuit 33b, an ignition coil 32b, a rectifying element 35 that rectifies a discharge current, a resistance element 37, a plasma generating capacitor 42b, and a plasma current. A rectifying element 43 for rectification, an insulating resin mold 201b made of epoxy resin or the like covering the rectifying element 43, and an insulating portion 205b formed in a cylindrical shape by an elastic member so as to be attached to the insulating member head portion 130 of the plasma ignition plug 10. The first terminal 210 connected to the center electrode terminal portion 111 is entirely covered by a case 200b that also serves as an electromagnetic wave shield, and the plug hole 52 of the engine block 51 is provided by a case screw portion 220b provided in the case 200. It is screwed inside. The case 200b may be entirely formed of metal, or may be formed of resin, and may be formed by covering part or all of the surface with metal plating.

  The ignition coil drive circuit 33b includes a transistor whose opening and closing is controlled by an externally provided electronic control unit (ECU) 34. The voltage from the power supply 40b is boosted by the ignition coil 32b to the high voltage plasma ignition plug 10. The supply is controlled.

The plasma generating capacitor 42b is charged by the power source 40b, and discharges a large current to the plasma spark plug 10 at the time of discharging.
In the present embodiment, the plasma generating capacitor 42 b is in a grounded state with the engine block 51, and also functions as an electromagnetic noise reducing capacitor that bypasses electromagnetic noise generated during discharge to the engine block 51.

  The power supply 40 to the contact 411 are connected by a resistance wire 41. At the contact 411, the primary side of the ignition coil 32 connected in parallel, the plasma generating capacitor 42b, and the rectifying element 43 that rectifies the plasma current are: Connected by resistanceless wire.

With reference to FIG. 7, the circuit configuration of the plasma ignition device 1b in the fourth embodiment of the present invention and the effects of the present invention will be described in detail.
The plasma ignition device 1b includes an ignition plug 10, a power source 40b, an ignition switch 31, an ignition coil 32b, an ignition coil drive circuit 33b including a transistor, an electronic control device 34, a resistance wire 36b, a rectifying element 35 that rectifies a discharge current, The resistor element 37, the resistor wire 41, the plasma generating capacitor 42b, the rectifying element 43 that rectifies the plasma current, and the element storage portion 2b are included.
The power source 40b is connected such that the negative side is grounded, the center electrode 110 of the spark plug 10 is an anode, and the ground electrode 130 is a cathode. Further, the power supply 40 to the contact 411 are connected by a resistance wire 41, and at the contact 411b, the primary side of the ignition coil 32b connected in parallel, the plasma generating capacitor 42b, and the rectifying element 43 for rectifying the plasma current are: Connected by resistanceless wire.

Between the secondary coil of the ignition coil 32b and the center electrode 110, a rectifying element 35 for rectifying the discharge current is provided in series via the high resistance wire 36b. Further, between the rectifying element 35 and the center electrode 110, A resistance element 37 is interposed in the immediate vicinity of the center electrode 110.
The rectifying element 43 that rectifies the plasma current is interposed in parallel with the rectifying element 35 that rectifies the discharge current between the plasma generating capacitor 42 b and the center electrode 110.

The rectifying element 35 for rectifying the discharge current, the rectifying element 43 for rectifying the plasma current, the plasma generating capacitor 42b, the ignition coil 32, and the ignition coil driving circuit 33b are covered with a case 200b, and the ground side of the plasma generating capacitor 42b and the case are covered. 200 is grounded.
Diodes are used for the rectifying element 35 that rectifies the discharge current and the rectifying element 43 that rectifies the plasma current.
In the present embodiment, a resistance wire of 16 kΩ / m is used as the resistance wire 36, and a resistance value that has a constant resistance value (for example, 1 kΩ) over the entire length from the power source 40 to the contact 411 is used as the resistance wire 41. The resistor element 37 is a 5 kΩ fixed resistor element, and the plasma generating capacitor is a capacitor having a capacity of 2 μF.
It has been found that if the resistance element 37 has a high resistance of 15 kΩ or more, electromagnetic noise can be suppressed, but the discharge is not sufficiently performed and the ignitability is affected. Therefore, 15 kΩ is a limit value at which discharge is sufficiently performed.
Further, it is desirable that only a part of the wiring length of the resistance wire 41 is a resistance wire, the length is constant in the wiring to each cylinder, and the other portion is a non-resistance electric wire so that the resistance value in each cylinder is equal. . At this time, the position where the resistance wire is used should be close to the plug 10 which is a noise generation source.

When the ignition switch 31 is turned on, the primary voltage of the power supply 40b is applied to the primary coil 321 of the ignition coil 32 by the ignition signal from the ECU 34, and the primary voltage is cut off by switching of the ignition coil drive circuit 33, the ignition coil 33 The internal magnetic field changes, and a positive secondary voltage of 10 to 30 kV is induced in the secondary coil 322 of the ignition coil 33 by the self-induction action.
On the other hand, the plasma generating capacitor 42b is connected in parallel with the plasma spark plug 10, and the plasma generating capacitor 42b is charged by the power source 40b.

  When the applied secondary voltage exceeds the discharge voltage between the center electrode 110 and the ground electrode 130, discharge is started between the two electrodes, and the gas in the discharge space 140 becomes a plasma state in a small region. This gas in the plasma state has conductivity, and causes the discharge of the electric charge stored between both electrodes of the plasma generating capacitor 42b, inducing further plasma state of the gas in the discharge space 140, and expanding the region. To do. The gas in the plasma state becomes high temperature and high pressure and is injected into the internal combustion engine.

At this time, although electromagnetic noise is generated, by placing the rectifying element 35 for rectifying the discharge current, the rectifying element 43 for rectifying the plasma current, and the plasma generating capacitor 42b as close as possible to the center electrode 110, Without accompanying the decay of the discharge voltage from the ignition coil 32b, only the high-frequency noise current generated at the time of discharge can be bypassed with the element storage portion 2b as the ground by the plasma generating capacitor 42b.
In addition, since the large current delivery line 430 that connects the plasma generating capacitor 42b and the center electrode 110 can be made extremely short, the element housing portion can be used even if the large current delivery line 430 does not serve as an antenna and electromagnetic noise occurs. 2b can be prevented from being transmitted to the outside.

Further, the ignition coil 32b and the ignition coil drive circuit 33b are placed in the element housing portion 2b, and the discharge delivery wire (resistance wire) 36b connecting the ignition coil 32b and the center electrode 110 can be shortened. The delivery line 36b does not serve as an antenna, and electromagnetic wave noise can be prevented from being transmitted to the outside.
In addition, the engine block 51 functions as an electromagnetic wave shield, and leakage of electromagnetic wave noise from the plug hole 52 can be prevented by comprehensively storing noise generation sources in the plug hole 52.
In the present embodiment, by using a boosted power source in which the voltage of the power source 40b is boosted in advance, the ignition coil 32b can be downsized, and the mountability can be improved.

FIG. 8 shows a configuration of a plasma ignition device 1c in which a plurality of plasma ignition plugs 10 according to a fifth embodiment of the present invention are mounted on an internal combustion engine 500 including a plurality of cylinders. In addition, since the same code | symbol was described in the figure about the part which is common in the 5th Embodiment of this invention, description is abbreviate | omitted.
In the present embodiment, in addition to the effects shown in the fifth embodiment, since the plurality of element storage portions 2 (1 to n) are formed by the case 200 having a constant shape, the stray capacitance is constant and the grounding is performed. Since the potential is constant, no new electromagnetic noise is generated due to the potential difference between the element storage portions.
Therefore, stable ignition by the plasma ignition device 1a can be realized in the hardly ignitable internal combustion engine 500 including a plurality of cylinders.
In the present embodiment, the resistance lines 41 (1 to n) are wired so as to be constant by using resistance lines and non-resistance lines.
Even if the wiring length to each cylinder changes on the circuit, the resistance value of each wiring of the full length of the resistance wire can be made substantially equal. Therefore, the resistance value per wiring length to each cylinder may be different. In addition, only a part of each wiring length may be a resistance wire, the length may be constant in the wiring to each cylinder, and the other part may be a resistance-free wire, and the resistance values in each cylinder may be equal. The position of the resistance line at this time is preferably used on the side closer to the plug which is a noise generation source.

  FIG. 9 shows an outline of a plasma ignition device 1d according to the sixth embodiment of the present invention. Although the basic configuration of the present embodiment is the same as that of the fourth embodiment, the ignition coil 32d and the ignition coil drive circuit 33d are disposed outside the element storage portion 2d, and the ignition coil 32d and the element storage portion 2d are arranged. A second terminal portion 230 is provided for connection, a third terminal 240 is provided for connection between the power supply 40 and the element storage portion 2d, and the second terminal 230 and the third terminal 240 are placed at positions orthogonal to each other. The difference is the arrangement.

In order to prevent the electromagnetic noise from leaking outside the storage portion 2d, it is necessary to be careful not to get electromagnetic noise between the plasma generating capacitor 42 and the third terminal portion 240.
Therefore, in this embodiment, the plasma generating capacitor 42 is separated from the rectifier 35 that rectifies the discharge current that generates electromagnetic wave noise and the wiring 36 thereof, and the second terminal portion 230 and the third terminal portion 240 are separated. It is as a structure.
It was found that the generation of electromagnetic noise can be further reduced by providing the plasma generating capacitor 42 in the vicinity of the third terminal 240.
In addition, by separating the mounting position of the plasma generating capacitor 42 from the second terminal unit 230, the high-voltage discharge voltage applied to the second terminal unit 230 leaks to the plasma generating capacitor 42. Can be prevented.
In addition, since the shape of the element storage portion 2d can be made simple, the manufacture is easy and the practicality is extremely high.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.
For example, in the above-described embodiment, a description has been given of the case where the plasma spark plug 10 that discharges the center electrode and the ground electrode in the discharge space formed inside the insulating member that covers the center electrode is used as the spark plug. However, the plasma ignition device of the present invention can be suitably used as a spark plug that discharges to the air gap between the center electrode and the ground electrode, or an extended surface discharge plug that discharges on the surface of the insulator, as an ignition plug. It is.

The principal part sectional view showing the composition of the plasma type ignition device in a 1st embodiment of the present invention. The block diagram which shows the evaluation method of a plasma type ignition device. The characteristic view which shows the effect of the plasma ignition device in the 1st Embodiment of this invention with a comparative example. The principal part sectional drawing which shows the structure of the plasma ignition device in the 2nd Embodiment of this invention. The principal part sectional drawing which shows the structure of the plasma ignition device in the 3rd Embodiment of this invention. The principal part sectional drawing which shows the structure of the plasma type ignition device in the 4th Embodiment of this invention. The circuit diagram of the plasma ignition device in the 4th Embodiment of this invention. The circuit diagram of the plasma ignition device in the 5th Embodiment of this invention. The principal part sectional drawing which shows the structure of the plasma ignition device in the 6th Embodiment of this invention. The circuit diagram which shows the structure and problem of the conventional plasma ignition device provided in the internal combustion engine which consists of a some cylinder. (A) is a circuit diagram which shows the structure of the conventional plasma ignition device, (b) is an operating characteristic figure which shows the operation | movement waveform in this figure. (A) is a circuit diagram which shows the structure of a normal spark plug, (b) is an operation characteristic figure which shows the operation | movement waveform in this figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma type ignition device 10 Plasma type spark plug 110 Center electrode 111 Center electrode terminal part 120 Insulating member 140 Ground electrode 140 Discharge space 2 Element storage part 32 Ignition coil 33 Ignition coil drive circuit 34 Electronic control unit (ECU)
35 Discharge current regulating rectifier elements 36, 371 Upstream discharge delivery line 37 Resistance element 370 Downstream discharge delivery line 30, 40 Power supply 410, 431 Upstream large current delivery line 42, 42a Capacitor 43 Plasma current rectifier rectification Element 430 Downstream large current distribution line 52 Plug hole (PH)
300 Discharge Power Supply Circuit 400 Plasma Generation Power Supply Circuit

Claims (17)

An ignition plug mounted on the internal combustion engine, a discharge power supply circuit, and a plasma generation power supply circuit are provided. A high voltage is applied from the discharge power supply circuit, and a large current is supplied from the plasma generation power supply circuit. In the plasma ignition device for igniting the internal combustion engine by applying a gas in a discharge space formed between the center electrode and the ground electrode of the ignition plug to a high temperature and high pressure plasma state by application,
A resistance element is interposed between the discharge power supply circuit and the center electrode,
A rectifying element is interposed between the plasma generating power supply circuit and the center electrode,
A plasma ignition device, wherein the resistance element and the rectifying element are placed in an element housing provided around the center electrode. Plasma ignition system according to claim 1, characterized in that the distance L ₁ from the lower end of the resistive element to the upper end of the center electrode was set to 30cm or less. Plasma ignition system according to claim 1 or 2, characterized in that the distance L ₂ from the lower end of the rectifier element to the upper end of the center electrode was set to 30cm or less. The total distance (L ₁ + L ₂ ) of the distance L ₁ from the lower end of the resistive element to the upper end of the center electrode and the distance L ₂ from the lower end of the rectifying element to the upper end of the central electrode is set to 30 cm or less. The plasma ignition device according to any one of claims 1 to 3, wherein:   5. The plasma ignition device according to claim 1, wherein the resistance element and the rectifying element are arranged side by side above the center electrode. 6.   The plasma ignition device according to any one of claims 1 to 5, wherein a part or all of the element storage portion is placed in a plug hole provided in an engine block of the internal combustion engine.   7. The plasma ignition device according to claim 1, wherein the element storage portion is provided so as to close an opening of the plug hole.   The plasma ignition device according to any one of claims 1 to 7, wherein the element housing portion includes a radio wave absorbing member made of a metal material or a magnetic material.   9. The plasma generating power supply circuit includes a plurality of capacitors charged by a power source, and a part or all of the capacitors are placed in the element housing portion. The plasma ignition device according to 1.   10. The discharge power supply circuit according to any one of claims 1 to 9, wherein the discharge power supply circuit includes boosting means for boosting a power supply voltage and a rectifying element for rectifying a discharge current, and the rectifying element is placed in the element housing portion. The plasma ignition device according to claim 1.   The discharge power supply circuit includes an ignition coil as the boosting means and an ignition coil drive circuit for driving the ignition coil, and the upper ignition coil is placed in the element housing portion. The plasma ignition device according to any one of 10 above.   The plasma ignition device according to any one of claims 1 to 11, wherein the resistance value of the resistance element is set to 3 kΩ or more, more preferably 5 kΩ or more.   The plasma ignition device according to any one of claims 10 to 12, wherein the ignition coil and a rectifying element that rectifies the discharge current are connected by a resistance wire.   The plasma ignition device according to claim 13, wherein the resistance value of the resistance wire is set to 10 to 20 kΩ / m. While connecting the power source and the capacitor by a resistance wire,
The plasma ignition device according to any one of claims 9 to 14, wherein the capacitor and the center electrode are connected by a wire without resistance.   The plasma ignition device according to claim 15, wherein a resistance value over the entire length of the resistance wire connecting the power source and the capacitor is set to a predetermined value of 1 kΩ or more.   The plasma ignition device according to any one of claims 13 to 16, wherein variation in the resistance value of the resistance wire is within ± 100Ω.

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