JP2013007351A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition device for an internal combustion engine capable of restraining a probabilistic fluctuation on a stretching effect of a discharge arc and attaining stable combustion in an internal combustion engine aiming stabilization of combustion by stretching the discharge arc while acting an air current generated in a cylinder on the discharge arc generated at the time of applying high voltage between a center electrode and a ground electrode.SOLUTION: As a discharge arc stretching determination means for determining whether or not the discharge arc 13 is actually stretched, the ignition device for an internal combustion engine includes magnetic field generation means MG, MGto calculate a voltage fluctuation rate ΔV (kV/ms) from discharge voltage VIG during a designated period (0.05 ms) and to generate a magnetic field in order to assist stretching of the discharge arc 13 owing to an air current TMB in a cylinder by making the magnetic field act on the discharge arc 13 when it is determined that the discharge arc 13 is not stretched by comparison with a designated threshold V.

Description

  The present invention relates to an ignition device for an internal combustion engine, and is particularly suitable for improving the ignitability of an extremely lean air-fuel mixture.

  In recent years, the flow of the air-fuel mixture generated in the combustion chamber is caused to act on the discharge arc generated when a high voltage is applied between the center electrode and the ground electrode of the spark plug, and the discharge arc is stretched to generate a lean mixture. Various ignition devices with improved ignitability have been proposed.

  For example, Patent Document 1 includes an annular housing that is mounted on an internal combustion engine and has a center electrode and a ground electrode that forms a discharge spark between the center electrode and is disposed on the outer periphery of the center electrode. In the spark plug for an internal combustion engine provided with an insulator provided between the center electrode and the housing and electrically insulating the center electrode and the housing, on the outer diameter surface of the end surface portion of the housing, There is disclosed a spark plug for an internal combustion engine provided with a rectifying means for controlling a tumble vortex of an air-fuel mixture in the combustion chamber of the internal combustion engine toward an inner central portion of the combustion chamber.

  As in Patent Document 1, by rectifying the flow of the air-fuel mixture generated in the combustion such as the tumble vortex in the combustion chamber and guiding it to a specific position between the center electrode and the ground electrode of the spark plug, A highly ignitable internal combustion engine, such as a high-supercharged engine or a lean combustion engine, by applying a tumble vortex to the discharge arc generated when a high voltage is applied between the center electrode and the ground electrode. It is expected that the ignitability can be improved.

  Further, as disclosed in Patent Document 2, in a direct injection internal combustion engine, the distance from the center position of the discharge gap of the ignition plug to the center position of the injection hole of the fuel injection valve and the center position of the discharge gap of the ignition plug By setting the distance from the fuel injection valve to the central axis of the injected fuel jet within a specific range, the fuel jet generated when the surrounding air is carried away by the fuel jet injected from the fuel injection valve It is expected that the ignitability can be improved by extending the discharge arc to the combustible region of the air-fuel mixture by applying a drawn air flow substantially opposite to the injection direction to the vicinity of the discharge gap of the spark plug.

However, when assembling the spark plug to the engine head of the internal combustion engine, the spark plug housing ends at the tip of the spark plug due to individual differences in the spark plug itself, variations in tightening torque, variations in the starting position of the threads formed on the engine head side, etc. The direction of the ground electrode extending in a substantially L shape is not necessarily a fixed direction.
Further, the strength and flow direction of the air-fuel mixture generated in the combustion chamber are not necessarily constant depending on the operation state of the internal combustion engine.
Therefore, as described in Patent Document 1 and Patent Document 2, whether or not the discharge arc is stretched when an air flow generated in the cylinder, such as a tumble vortex flow or a fuel injection pull-in flow, is applied to the tip of the spark plug. Became a stochastic event, and it was found that the discharge arc might not be stretched as expected.

As shown in FIG. 11 (a), a combustion tester simulating an engine is used as shown in FIG. 11 (a) so that the shaft portion of the ground electrode 12 is on the upstream side with respect to the center electrode 11 of the spark plug 10. In a state where the airflow TMB is flowing, a 500-cycle combustion test is performed under the conditions of engine speed: 2000 rpm, energy applied to the spark plug 10: 150 mJ, air-fuel ratio A / F = 25.3, and airflow TMB in the combustion chamber. Is the result of investigation by measuring the indicated mean effective pressure Pmi and the discharge voltage when the spark plug 10 is applied between the center electrode 11 and the ground electrode 12 of the spark plug 10 or by observing the discharge arc with a monitor monitor camera.
As shown in this figure (b), the discharge arc is extended at 414 cycles corresponding to approximately 82% in 500 cycles, and as shown in this figure (c), the discharge arc is performed at 86 cycles corresponding to approximately 18% in 500 cycles. No extension was made. If the discharge arc is not extended, the target indicated mean effective pressure is not reached, and combustion may be deteriorated by the combustion cycle.

  Therefore, for example, when the shaft portion of the ground electrode 12 extending in a substantially L shape in the combustion chamber is on the upstream side of the in-cylinder airflow TMB with respect to the center electrode 11, it is between the center electrode 11 and the ground electrode 12. There is a possibility that the flow velocity of the inflowing airflow is decelerated by the collision with the shaft portion of the ground electrode 12, the discharge arc generated between the center electrode 11 and the ground electrode 12 is not sufficiently stretched, and the effect of improving the ignitability cannot be exhibited. Whether or not the discharge arc is sufficiently stretched by the air flow generated in the combustion chamber, such as a tumble vortex or a drawn flow generated by fuel injection, becomes a stochastic event, which may impair ignition stability.

  Therefore, in view of such a situation, the present invention causes an air flow generated in a cylinder to act on a discharge arc generated when a high voltage is applied between a center electrode and a ground electrode facing each other with a predetermined discharge distance. A highly reliable internal combustion engine ignition device that suppresses stochastic fluctuations in the effect of extending the discharge arc and always realizes stable combustion in an internal combustion engine that extends the discharge arc to stabilize combustion.

  According to the first aspect of the present invention, a high voltage is applied to a spark plug provided in the internal combustion engine, and a discharge arc generated between the center electrode and the ground electrode facing each other through an insulator is generated in the combustion chamber of the internal combustion engine. An ignition device for an internal combustion engine that ignites an air-fuel mixture introduced into a combustion chamber by extending the discharge arc by applying an air current to the discharge arc, and whether or not the discharge arc is actually extended A discharge arc stretch determination means for determining; and when the determination means determines that the discharge arc is not stretched, a magnetic field is applied to the discharge arc to assist the extension of the discharge arc by the in-cylinder airflow. Magnetic field generating means for generating.

  In the invention of claim 2, the discharge arc extension determination means includes a discharge voltage detection means for detecting a discharge voltage of the spark plug, a voltage increase rate calculation means for calculating a voltage increase rate with respect to a minute time of the discharge voltage, Threshold determination means for determining that the discharge arc is stretched when the voltage increase rate is equal to or greater than the threshold value by comparing the voltage increase rate at a predetermined time from the start of discharge with a predetermined threshold value.

  According to a third aspect of the present invention, the magnetic field generating means comprises two magnetic field generating means that are orthogonal to the direction of the magnetic field generated by energization, and it is determined that the discharge arc is not extended by the discharge arc extension determining means. When one of the two magnetic field generating means is applied, power is supplied to one or both of the two magnetic field generating means.

It is known that the ignitability can be improved by causing the in-cylinder airflow to act on the discharge arc generated between the center electrode and the ground electrode, and extending the discharge arc. The stretching is a stochastic event that varies depending on the engine operating condition and the state in which the spark plug is assembled in the combustion chamber, and the discharge arc is not always stably stretched by the in-cylinder airflow.
However, according to the first aspect of the present invention, when the discharge arc stretch determining means determines that the discharge arc is not stretched, the magnetic field generating means is energized and the Lorentz force due to the magnetic field is applied to the discharge arc. When the discharge arc is curved, the discharge arc can be reliably stretched by the in-cylinder airflow, and stable ignition can be realized.
Further, when the discharge arc extension determining means determines that the discharge arc is extended, the magnetic field generating means is not energized, and wasteful energy consumption can be suppressed.

When the discharge arc is stretched by the in-cylinder airflow, the discharge voltage at the predetermined time greatly fluctuates from the start of the discharge, and when the discharge arc is not stretched by the in-cylinder airflow, the discharge starts. From the above, it was found that the fluctuation of the discharge voltage in a predetermined time was small.
Based on this knowledge, as in the invention of claim 2, it is possible to easily determine whether or not the discharge arc is stretched by determining the threshold value of the voltage increase rate of the discharge voltage with respect to a predetermined time. New findings have been obtained.

  According to the invention of claim 3, by changing the generation direction of the magnetic field to selection, the internal combustion engine can realize extremely stable ignition with less energy loss and more reliably extending the discharge arc. An ignition device can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS The outline | summary of the ignition device for internal combustion engines in the 1st Embodiment of this invention is shown, (a) is a top view which desires an engine head side from a combustion chamber side, (b) is AA in this figure (a). FIG. The perspective view which shows the 1st effect of the ignition device for internal combustion engines shown in FIG. 1 in order of (a) to (c). The effect of this invention is shown, (a) is a characteristic diagram which shows the time-dependent change of a discharge voltage, (b) is a characteristic diagram which shows the time-dependent change of a voltage increase rate. The perspective view which shows the 2nd effect of the ignition device for internal combustion engines shown in FIG. 1 in order of (a) to (c). FIG. 4 shows a second effect of the present invention, wherein (a) is a characteristic diagram showing a change with time of discharge voltage, and (b) is a characteristic diagram showing a change with time of voltage increase rate. The flowchart which shows an example of the control method of the magnetic field generation means used for this invention. The schematic diagram which shows the effect of this invention when a spark plug is arrange | positioned in arbitrary directions. In a state where the discharge arc is not stretched by the in-cylinder airflow, (a) is a characteristic diagram showing a change with time of the discharge voltage, and (b) is a characteristic diagram showing a change with time of the voltage increase rate. In a state where the discharge arc is extended by the in-cylinder airflow, (a) is a characteristic diagram showing a change with time of the discharge voltage, and (b) is a characteristic diagram showing a change with time of the voltage increase rate. FIG. 3 shows a threshold selection method for determining whether or not to drive a magnetic field generating means in the ignition device of the present invention. FIG. 4 (a) shows the change over time in the voltage increase rate when the discharge arc is not stretched. The characteristic figure shown, (b) is a characteristic figure which shows the time-dependent change of the voltage increase rate in the state where the discharge arc is extended. The problem of the ignition device using the conventional in-cylinder air flow for extending the discharge arc is shown. (A) is a cross-sectional view of the main part showing the measurement conditions of the indicated mean effective pressure, and (b) is the drawing of the discharge arc. (C) is a characteristic diagram when the discharge arc is not stretched.

With reference to FIG. 1, the outline | summary of the ignition device 1 for internal combustion engines in embodiment of this invention is demonstrated.
FIG. 1 (a) is a plan view of the internal combustion engine (hereinafter abbreviated as E / G) 5 to which the ignition device 1 according to the present embodiment is applied from the combustion chamber side to the engine head side, and FIG. It is arrow sectional drawing along AA in figure (a).

As shown in the figure, the E / G 5 includes an engine head 50, a substantially cylindrical cylinder 54, and a piston 53 movably housed in the cylinder 52, and an inner wall of the engine head 50 and an inner peripheral wall of the cylinder 54. And the top surface of the piston 53 define a combustion chamber 500.
The engine head 50 is formed with an intake cylinder 510 that is opened and closed by an intake valve 511 and an exhaust cylinder 520 that is opened and closed by an exhaust valve 521.
The engine head 50 includes a fuel injection valve (INJ) that sprays high-pressure fuel FL in the combustion chamber 500, and an ignition plug 10 that ignites an air-fuel mixture that is generated by a discharge arc generated by application of a high voltage and introduced into the combustion chamber. When an engine control unit (ECU) 30 incorporating a discharge arc stretching determining means and the discharge voltage detecting unit is an essential part of the present invention, the first magnetic field generating means MG ₁ and the second magnetic field generating means as a magnetic field generating means MG ₂ is provided.
Either one of the first and the magnetic field generating means MG ₁ and the second magnetic field generating means MG _2, or by energizing the both, the discharge arc generated between the center electrode 11 of the spark plug 10 and the ground electrode 12 The Lorentz forces F _LNZ 1 and F _LNZ 2 can be selectively acted on 13 to bend in a desired direction.

The first magnetic field generating means MG ₁ and the second magnetic field generating means MG ₂ are provided at positions where the directions of the generated magnetic fields MGF ₁ and MGF ₂ pass through the central axis of the spark plug 10 and are orthogonal to each other. The Lorentz forces F _LNZ 1 and F _LNZ 2 are generated in directions orthogonal to the discharge arc 13 generated when a high voltage is applied between the center electrode 11 and the ground electrode 12 of the spark plug 10. be able to.

The ignition control means (IGC) 20 is a known ignition control means including at least switching elements such as IGBTs and thyristors and a booster circuit for boosting a power supply voltage such as a DC-DC converter and a booster coil to a high voltage. / A high voltage is applied between the center electrode 11 and the ground electrode 12 of the spark plug 10 in accordance with the ignition signal IGt transmitted from the ECU 30 according to the operating state of / G5, and the discharge arc 13 is generated. The IGC 20 may be either a so-called induction discharge type (TCI) ignition control means or a capacity discharge type (CDI) ignition control means.
Further, the IGC 20 includes voltage detection means (not shown), monitors the change with time of the discharge voltage V _IG applied to the spark plug 10, and transmits it to the ECU 30.

Further, as the voltage increase rate calculating unit, the ECU 30, the discharge voltage _{V IG,} for example, calculates a voltage increase rate ΔV in short time of each 0.05 ms.
The voltage increase rate ΔV, as shown in equation (1), and the absolute value of the discharging amount of change in voltage _{V IG} (kV) and divided by 0.05ms between 0.05ms.

The magnetic field generation control means (MGC) 40 includes threshold value determination means for determining a threshold value of the voltage increase rate ΔV according to a magnetic field control method described later, and includes a first magnetic field generation means MG ₁ and a second magnetic field generation means MG _2. The first magnetic field generating means (MG ₁ ) and / or the second magnetic field generating means (MG ₂ ) is energized according to the discharge voltage V _IG detected by the IGC 20. The first magnetic field MGF ₁ or / and the second magnetic field MGF ₂ are applied to the discharge arc 13 generated between the center electrode 11 and the ground electrode 12, and each of the magnetic fields MGF ₁ and MGF ₂ is applied. A first Lorentz force F _LNZ 1 / and / or a second Lorentz force F _LNZ 2 in a direction orthogonal to the direction is generated.

Here, with reference to FIG. 2 and FIG. 3, an effect when the first magnetic field generating means MG ₁ generates the first magnetic field MGF ₁ will be described.
For example, when the spark plug 10 is assembled to the cylinder head 50 in a direction in which the leg portion 120 of the ground electrode 12 extending in an approximately L shape toward the combustion chamber is upstream with respect to the airflow TMB flowing in the cylinder, As shown in FIG. 2A, when the discharge arc 13 is generated between the tip of the center electrode 11 and the discharge portion 121 of the ground electrode 12, the leg portion 120 of the ground electrode 12 serves as a barrier, and the discharge arc 13 Is not stretched without being exposed to the in-cylinder airflow TMB.
In a non-ignitable engine such as a stratified combustion engine or a highly supercharged combustion engine, there is a risk of misfire if it continues.
Thus, when the discharge arc 13 is not stretched by the in-cylinder airflow, the first magnetic field generating means MG ₁ is driven to cause the first magnetic field MGF ₁ to act on the discharge arc 13. Then, as shown in the figure (b), so that the first Lorentz force _{F LNZ} 1 by the discharge arc 13 in a direction orthogonal to the first magnetic field MGF1 is stretched in the direction of action of the Lorentz force _{F LNZ} 1 .
Then, the discharge arc 13 protrudes from the shadow of the leg portion 120 of the ground electrode 12 and is exposed to the in-cylinder airflow TMB, and is elongated by the in-cylinder airflow TMB as shown in FIG. Thus, ignition of a non-ignitable engine becomes possible.

FIG. 3 shows changes in the discharge voltage V _IG detected by the voltage detection means at this time and changes with time in the voltage increase rate ΔV.
As shown in FIG. 3 (a), the discharge start is not stretched is between discharge arc 13 for a period of time t _1, as shown in the figure (b), the voltage increase rate ΔV predetermined threshold V _{REF (e.g.,} If lower than 2 kV / ms), the first magnetic field generating means MG ₁ is energized.
At this time, when the first Lorentz force F _LNZ 1 acts on the discharge arc 13 and the discharge arc 13 is stretched by the in-cylinder airflow TMB, the discharge voltage V _IG changes greatly as shown in FIG.
In the spark plug 10, the discharge arc 13 is generated between the center electrode 11 and the ground electrode 12, and the discharge arc 13 is stretched by the in-cylinder airflow TMB and the discharge voltage VIG starts to change from the start of discharge. When the time of about 0.2 ms elapses, the discharge arc 13 is maintained for a period of about 2 ms.

Further, in the present embodiment, the spark plug 10 is a so-called spark plug that generates a discharge arc 13 when a high voltage is applied between the center electrode 11 and the ground electrode 12 facing each other through an insulator (not shown). However, the material and shape of the center electrode 11 and the ground electrode 12 are not particularly limited, and known spark plugs can be appropriately employed.
In the present embodiment, the first and second Lorentz forces F are regarded as a current flowing from the center electrode 11 to the ground electrode 12 with the center electrode 11 side as a positive electrode and the ground electrode 12 side as a negative electrode. _Although directions of _LNZ 1 and F _LNZ 2 are illustrated, if the polarities of the center electrode 11 and the ground electrode 12 are reversed, the directions of the acting Lorentz forces F _LNZ 1 and F _LMNZ 2 are also reversed.

Next, with reference to FIG. 4 and FIG. 5, an effect when the second magnetic field generation unit MG ₂ generates the second magnetic field MGF ₂ will be described.
For example, as shown in FIG. 5A, when the spark plug 10 is assembled so that the leg 120 of the ground electrode 1 is on the downstream side of the in-cylinder airflow TMB, the leg 120 of the ground electrode 12 discharges. Even if the extension of the arc 13 is interrupted and the magnetic field MGF ₁ acts on the discharge arc 13 by the energization of the _first magnetic field generating means MG ₁ as described above, as shown in FIG. in the case where not lead to stretching of the discharge arc 13, as shown in the figure (c), the second energization of the magnetic field generating means MG ₂ is performed, the addition to the first Lorentz force F _{LNZ 1} 2 The Lorentz force F _LNZ 2 acts on the discharge arc 13 to change the bending direction of the discharge arc 13, and the discharge arc 13 is greatly stretched by the in-cylinder airflow TMB.
The discharge voltage V _IG (kV) and the voltage change rate ΔV (kV / ms) at this time are shown in FIG.

As shown in FIG. 5A, in this embodiment, even if the first magnetic field MGF _{1 is applied} to the discharge arc 13 by energizing the first magnetic field generating means MG ₁ , ), At a predetermined time t ₂ , the voltage increase rate ΔV is lower than a predetermined threshold value V _REF (for example, ₂ kV / ms), so that the second magnetic field generating means MG ₂ is energized, and the second The magnetic field MGF _{2 is applied} to the discharge arc 13.
Then, the discharge arc 13 is stretched by the in-cylinder airflow TMB, and the discharge voltage _VIG changes greatly as shown in FIG.
Note that once the discharge arc is stretched by the in-cylinder airflow TMB, the energization to the first magnetic field generating means MG ₁ and / or the second magnetic field generating means MG ₂ may be terminated.

With reference to FIG. 6, an example of the control method of the magnetic field generation means in the present invention will be described.
When the ignition signal IGt is oscillated from the ECU 30, the control flow of the magnetic field generating means is started using this as a trigger.
In the first determination necessity determination step of step S100, it is determined whether or not it is the first determination time for determining whether or not energization to the first magnetic field generating means MG1 is necessary from the start of discharge.
Until the constant time t ₁ from the start of discharge, the change in the discharge voltage V _IG is small, and the loop of step S100 is repeated until the passage of t ₁ .
When the predetermined time t ₁ is reached, the determination in step S100 is Yes, and the process proceeds to the first magnetic field generation necessity determination step in step S110. In the first magnetic field generation necessity determination process of S110, a first threshold value determination is performed by comparing the voltage increase rate ΔV with a predetermined threshold value _VREF . At this time, if ΔV <V _{REF, the} determination is Yes, and the process proceeds to the first magnetic field generation process in step S120.
In the first magnetic field generation process of step S120, energization of the first magnetic field generation means is started (MG ₁ ON) in order to _{apply the} first Lorentz force F _LNZ 1 to the discharge arc 13.
In step S110, if the voltage increase rate is equal to or greater than a predetermined threshold value, that is, ΔV ≧ _VREF, it is determined No, it is determined that energization of the magnetic field generating means is unnecessary, and the process proceeds to the end step of step S160, where the first magnetic field generating means MG1, energizing the second magnetic field generating means MG ₂ together is not performed.
That is, when the discharge arc 13 is extended by the in-cylinder airflow TMB without assistance from the magnetic field, the energy can be limited without energizing the magnetic field generating means MG ₁ and MG ₂ .
Then, in the second determination necessity determination process of step S130, if the first determination timing whether judges is determined whether or not to the energization of the second magnetic field generating means MG _2.
In step S130, until the predetermined time t2 elapses, the determination is No, the second determination is not performed, and the loop of steps S100 to S130 is repeated. When the predetermined time t2 has elapsed in step S130, the determination becomes Yes, and the process proceeds to the second magnetic field generation necessity determination step in step S140.
In the second magnetic field generation necessity determination step in step S140, a second threshold value determination is performed by comparing the voltage increase rate ΔV with a predetermined threshold value _VREF . At this time, if ΔV <V _{REF, the} determination is Yes, and the process proceeds to the second magnetic field generation process in step S150.
That is, if the voltage increase rate becomes equal to or greater than the predetermined threshold value V _REF due to energization of the _first magnetic field generation means MG1, it is not necessary to energize the second magnetic field generation means MG2, so that the determination is No, step S160. Proceed to the end of the process.
In the second magnetic field generating process in step S150, the energization of the second to the magnetic field generating means MG ₂ is made, until the judgment No in the step 140 is repeated loop of steps S140, S150.
By energization of the second to the magnetic field generating means MG _2, the discharge arc 13 is stretched by the cylinder airflow TMB, when the discharge voltage _{V IN} is equal to or greater than a predetermined threshold value _{V REF,} a second magnetic field generating necessity determination step S140 In the process, the determination is Yes, and the process proceeds to an end process of step 160.

With reference to FIG. 7, it will be described that the present invention is effective even when the spark plug 10 is assembled in an arbitrary direction. Note that the configuration of the spark plug 10 is the same as that of the above-described embodiment, and the effect of the present invention and the effect when only the direction of the ground electrode 12 is different when the spark plug 10 is assembled to the cylinder head 50 are clarified. For this reason, in this figure, the lead lines and symbols indicating the leg portions 120 of the center electrode 11 and the ground electrode 12 are omitted.
FIGS. (A-1), (a-2), and (a-3) show positions where the position of the leg 120 of the ground electrode 12 does not affect the extension of the discharge arc 13 by the in-cylinder airflow TMB. In such a case, the in-cylinder airflow TMB directly stretches the discharge arc 13, and stable ignition can be realized even in a non-ignitable engine. Therefore, the first magnetic field generating means MG ₁ and the second magnetic field generating means None of MG ₂ needs to be activated and does not consume energy to generate a magnetic field.

Further, positioned on the upstream side of the ground electrode 12 cylinder air flow TMB, if the discharge arc 13 is hidden behind the leg 120 of the ground electrode 12, the energization of the first magnetic field generating means MG ₁ as described above When the first Lorentz force F _LNZ 1 acts on the discharge arc 13, as shown in this figure (b-1), the direction not hidden behind the ground electrode 12, that is, the flow of the in-cylinder airflow TMB The discharge arc 13 is stretched obliquely downstream with respect to the direction, and the in-cylinder airflow TMB acts on the discharge arc 13 stretched by the first Lorentz force F _LNZ 1, and FIG. without performing energization (b-3) in the second magnetic field generating means MG ₂ as shown, the discharge arc 13 by cylinder airflow TMB is stretched, is also stable ignition in the flame ignitability of the engine realizable.

Further, when the leg portion 120 of the ground electrode 12 is positioned obliquely downstream of the in-cylinder airflow TMB with respect to the center electrode 11, the discharge arc 13 is not stretched by the in-lady airflow TMB. While one current supply to the magnetic field generating means MG ₁ is performed, as shown in the figure (c-1), since the first Lorentz force FLNZ1 acts in the direction toward the leg 120 of the ground electrode 12, Even after the first magnetic field generating means MG1 is energized, the discharge arc 13 is not stretched, and the second magnetic field generating means MG2 is energized, and as shown in FIG. Since the resultant force of the first Lorentz force F _LNZ 1 and the second Lorentz force F _LNZ 2 acts, the discharge arc 13 is greatly curved in a direction perpendicular to the in-cylinder airflow TMB, and the in-cylinder airflow TMB is Acting As shown in FIG. (C-3), so that the discharge arc 13 is stretched while bypassing the ground electrode 12.

Further, the leg portions 120 of the ground electrode 12, when positioned on the downstream side of the in-cylinder airflow TMB, the first energization of the magnetic field generating means MG ₁ is performed, as shown in the figure (d-1), Although the discharge arc 13 bends in the obliquely downstream direction, since the leg portion 120 of the ground electrode 12 exists on the downstream side of the in-cylinder airflow TMB, the discharge arc 13 is easily affected by the flame extinguishing action of the ground electrode 12. As shown in d-2), the first magnetic field generating means MG ² is energized and the second Lorentz force F _LNZ 2 is also applied, whereby a ground electrode discharge is obtained and the discharge arc 13 is greatly curved. The in-cylinder airflow TMB acts, and the discharge arc 13 is stretched so as to bypass the ground electrode 12 as shown in FIG.
That is, as shown in the figure, according to the present invention, a magnetic field is effectively applied to an arbitrary direction of the spark plug 10 to enable the discharge arc 13 to be extended by the in-cylinder airflow TMB, and the internal combustion engine Stable ignition can be realized in the engine.

Here, the background to the present invention will be described with reference to FIG. 8, FIG. 9, and FIG.
FIG. 8A shows the discharge voltage V _IG when the in-cylinder airflow is not acting on the discharge arc 13, and FIG. 8B is a characteristic diagram showing the change in the voltage increase rate ΔV at that time. .
As shown in FIG. 8A, in a state where the in-cylinder airflow TMB does not act on the discharge arc 13 and the discharge arc 13 is not stretched, the discharge voltage _VIG hardly changes and the voltage increase rate ΔV The change is small.
On the other hand, FIG. 9A shows the discharge voltage _VIG in a state where the in-cylinder airflow is acting on the discharge arc 13, and FIG. 9B is a characteristic diagram showing the change in the voltage increase rate ΔV at that time. It is.
As shown in FIG. 9A, in a state where the in-cylinder airflow TMB acts on the discharge arc 13 and the discharge arc 13 is stretched, the discharge voltage V _IG changes greatly, and the voltage increase rate ΔV changes. Is also big.
Therefore, the inventors have obtained knowledge that it is possible to determine whether or not the discharge arc 13 is stretched by the in-cylinder airflow TMB by determining the threshold value of the voltage increase rate ΔV.
Further, as shown in FIG. 10, since a high voltage of, for example, 20 kV or higher is applied to the spark plug 10 by the ignition control device IGC, dielectric breakdown occurs, and the resistance of the discharge space decreases at a stretch. Is excluded from the judgment time because it is extremely large. In addition, the period of 2 ms or longer when the discharge ends is excluded from the determination time because the change in the voltage increase rate is large due to the influence of the ion current generated in the combustion chamber due to combustion.
As shown in FIG. 10A, in a state where the discharge arc 13 is not stretched, the maximum value of the voltage increase rate ΔV in the determination period is set to V _REF , and the voltage increase rate ΔV is converted into an absolute value by As shown in FIG. 10B, attention is paid to the fact that the state in which the discharge arc 13 is stretched can be recognized by comparison with the threshold value _VREF .
In this figure, the change in the relative value of the actually measured voltage increase rate is indicated by a one-dot chain line, and the change in the absolute value obtained by inverting the negative value is indicated by a solid line.

In the present invention, which of the first magnetic field generating means MG ₁ and the second magnetic field generating means MG ₂ is preceded depends on the direction of the air flow generated in the combustion chamber of the internal combustion engine actually applied, It can be changed as appropriate depending on the mounting position of the spark plug.
In the above embodiment, when the discharge arc is not extended by the first magnetic field generating means, the energization to the second magnetic field generating means is maintained while the energization to the first magnetic field generating means is maintained. Although the example of the control method which performs is shown, you may make it selectively perform electricity supply to any one.
Further, the number of magnetic field generating means is not limited to the first and second, but by providing two or more magnetic field generating means, a state where the discharge arc is not stretched using Lorentz force is avoided. The number of magnetic field generating means can be changed as appropriate unless it is contrary to the spirit of the present invention.
In addition, by changing the direction of the current applied to the magnetic field generating means, the direction of the generated magnetic field is changed, the direction of the Lorentz force acting on the discharge arc is changed, and the combination that can extend the discharge arc most effectively is actually performed. It is also possible to learn while repeating the combustion stroke and to select the optimum conditions.
Also in this case, it is possible to determine whether or not the condition is an effective magnetic field generation condition by determining the threshold value of the voltage increase rate ΔV.

DESCRIPTION OF SYMBOLS 1 Ignition device 10 for internal combustion engines Spark plug 11 Center electrode 12 Ground electrode 13 Discharge arc 20 Ignition control device (IGC)
30 Engine control unit (ECU)
40 Magnetic field controller (MGC)
5 Internal combustion engine 50 Cylinder head 500 Combustion quality 510 Intake cylinder 511 Intake valve 520 Exhaust cylinder 521 Exhaust valve 53 Cylinder block 54 Piston INJ Fuel injection valve MG ₁ First magnetic field generation means MG ₂ Second magnetic field generation means F _LNZ 1 First 1 Lorentz force F _LNZ 2 2nd Lorentz force TMB Combustion air flow FL Fuel spray

JP 2006-28820 A JP 2011-106377 A

Claims (3)

By applying a high voltage to the spark plug provided in the internal combustion engine and causing the air flow generated in the combustion chamber of the internal combustion engine to act on the discharge arc generated between the center electrode and the ground electrode facing each other through the insulator, An ignition device for an internal combustion engine that ignites an air-fuel mixture introduced into a combustion chamber by extending the discharge arc,
Discharge arc extension determination means for determining whether or not the discharge arc is actually extended;
A magnetic field generating means for generating a magnetic field to assist the extension of the discharge arc by the in-cylinder airflow when a magnetic field is applied to the discharge arc when the determination means determines that the discharge arc is not extended; An internal combustion engine ignition device.   The discharge arc extension determination means includes a discharge voltage detection means for detecting a discharge voltage of the spark plug, a voltage increase rate calculation means for calculating a voltage increase rate with respect to a minute time of the discharge voltage, and the above-mentioned at a predetermined time from the start of discharge. 2. The ignition device for an internal combustion engine according to claim 1, further comprising threshold value determining means for determining that the discharge arc is stretched when the voltage increase rate is equal to or greater than the threshold value by comparing the voltage increase rate with a predetermined threshold value.   The magnetic field generating means comprises two magnetic field generating means that are orthogonal to each other in the direction of the magnetic field generated by energization. When the discharge arc extension determining means determines that the discharge arc is not extended, the two magnetic fields are The internal combustion engine ignition device according to claim 1 or 2, wherein power is supplied to one or both of the generating means.

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