JP5658872B2 - Ignition device for spark ignition internal combustion engine - Google Patents

Description

  The present invention relates to an ignition device for a spark ignition type internal combustion engine that generates plasma by reacting an electric field generated in a combustion chamber with a spark discharge by an ignition plug to ignite an air-fuel mixture.

  2. Description of the Related Art Conventionally, in a spark ignition internal combustion engine mounted on a vehicle, particularly an automobile, an air-fuel mixture in a combustion chamber is ignited at each ignition timing by spark discharge between a center electrode and a ground electrode of a spark plug. In such ignition by an ignition plug, for example, in an internal combustion engine of a type in which fuel is directly injected into a cylinder, if the injected fuel is not distributed at the spark discharge position of the ignition plug, it rarely occurs.

  For this reason, in such an internal combustion engine, a plasma atmosphere is generated in the discharge region of the spark plug, for example, as described in Patent Document 1, in order to compensate for the spark discharge of the spark plug, and an arc is generated in the plasma atmosphere. It is known that the discharge is performed to surely ignite the air-fuel mixture in the combustion chamber without applying a higher voltage than in the past and to obtain a stable flame.

JP 2007-32349 A

  By the way, when the air-fuel mixture is ignited by combining the plasma atmosphere and the spark discharge, the center is widely used at present without using a spark plug having a special electrode structure such as that described in Patent Document 1. Attempts have been made to achieve similar ignition by means of a spark plug having an electrode and a ground electrode. In this case, in order to apply, for example, a high-frequency voltage for generating a plasma atmosphere to the center electrode of the spark plug, a high-frequency power source is electrically connected and an ignition coil is electrically connected so that spark discharge occurs. .

  However, with such a configuration, a high-voltage current generated in the ignition coil at the time of spark discharge is applied to the high-frequency power supply via the center electrode, and the high-voltage power supply in the high-frequency power supply As a result, the high frequency power supply may generate electromagnetic noise. Such electromagnetic noise may adversely affect an electromagnetic sensor attached to the internal combustion engine and an electronic control device that controls the operating state of the internal combustion engine.

  Therefore, the present invention aims to eliminate such problems.

That is, the ignition device for a spark ignition type internal combustion engine according to the present invention is electrically connected to an ignition plug of the spark ignition type internal combustion engine and applies a high voltage to the ignition plug, and is electrically connected to the ignition plug. An ignition device for a spark ignition internal combustion engine comprising an electric field generation circuit for generating an electric field in a combustion chamber, wherein the spark ignition internal combustion engine includes a spark discharge generated in a spark plug by a high voltage, a generated electric field, To generate plasma and ignite the air-fuel mixture. When a high voltage for spark discharge is generated in the ignition coil, the electric field generation circuit is electrically insulated from the ignition coil. held in includes an insulating holding means, the insulating holding means, opposite direction to the direction of current tends to flow between the ignition coil and the electric field generator to the ignition coil via a signal line to be connected to the spark plug Ri Na using placed the diode, an AC voltage generating circuit field generating circuit generates an AC voltage, to generate a pulsating voltage to the diode is applied to the spark plug by rectifying the AC voltage Features.

  According to such a configuration, when a high voltage for spark discharge is generated in the ignition coil, the insulation holding means holds the electric field generation circuit in a substantially insulated state, so that the high voltage for spark discharge generates the electric field. Prevent entry into the circuit. As a result, it is possible to suppress electromagnetic interference (EMI) caused by the high voltage entering the electric field generating circuit.

The spark ignition internal combustion engine ignition device of the present invention is electrically connected to an ignition plug of the spark ignition internal combustion engine to apply a high voltage to the spark plug, and is electrically connected to the spark plug. An ignition device for a spark ignition internal combustion engine comprising an electric field generation circuit for generating an electric field in a combustion chamber, wherein the spark ignition internal combustion engine includes a spark discharge generated in a spark plug by a high voltage, a generated electric field, To generate plasma and ignite the air-fuel mixture. When a high voltage for spark discharge is generated in the ignition coil, the electric field generation circuit is electrically insulated from the ignition coil. Insulating holding means is held in a direction opposite to the direction of current flowing between the ignition coil and the electric field generating circuit via a signal line connecting the ignition coil to the ignition plug. Arrangement It using the diodes is, between the field generator and the signal line, and characterized in that each provided with the diode between the ground line to be connected to the metal portion of the field generator and the internal combustion engine you.

  Examples of the electric field generating circuit include an AC voltage generating circuit that applies an AC voltage to the spark plug, and a pulsating voltage generating circuit that also applies a pulsating voltage to the spark plug. The AC output from the AC voltage generation circuit is preferably about 200 kHz to 500 MHz and about 3 kVp-p to 10 kVp-p.

  The pulsating voltage generation circuit may be any circuit that generates a DC voltage whose voltage periodically changes, and the waveform of the DC voltage may be arbitrary. That is, the pulsating voltage in the present application changes from a reference voltage including 0 volt to a pulse voltage that changes to a constant voltage at a constant cycle or a voltage that increases or decreases sequentially at a fixed cycle, for example, AC voltage is half-wave rectified. Such a DC voltage having such a waveform, and a DC voltage obtained by applying a DC bias to the AC are included. In this case, the fixed period may correspond to the above-described frequency. The waveform may be a sine wave, a sawtooth wave, a triangular wave, or the like.

  The present invention is configured as described above, and when a high voltage for spark discharge is generated in the ignition coil, the insulation holding means holds the electric field generation circuit in a substantially insulated state. High voltage can be prevented from entering the electric field generating circuit, and electromagnetic interference (EMI) caused by the high voltage entering the electric field generating circuit can be suppressed.

The block diagram which shows the structure of embodiment of this invention. The block diagram which shows the structure of the electric field generation circuit of the embodiment. The circuit diagram of the H bridge circuit of the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  A spark ignition internal combustion engine (hereinafter referred to as an engine) 100 is, for example, a three-cylinder engine, and includes a spark plug 1 that is attached facing the inside of a combustion chamber of each cylinder. The engine 100 itself has a structure well known in this field, and the description of the structure is omitted.

  An ignition device 4 is electrically connected to a spark plug 1 having a center electrode 2 and a ground electrode 3. The ignition device 4 includes an igniter 5, an ignition coil 6, a mixer 7, an electric field generation circuit 8, and a first diode 9 and a second diode 10 which are insulation protection means. The igniter 5 receives an ignition timing signal output from an electronic control device (not shown) for controlling the operation of the engine 100 and outputs an ignition pulse signal to the ignition coil 6. The ignition coil 6 includes a primary side winding and a secondary side winding, and generates a negative high voltage pulse voltage in the secondary side winding by an ignition pulse signal from the igniter 5. The igniter 5 and the ignition coil 6 may have a structure well known in this field. The mixer 7 is connected to the secondary winding of the ignition coil 6 and is connected to the first diode 9 to transmit the high-voltage pulse voltage of the ignition coil 6 to the center electrode 2 of the ignition plug 1 and an electric field generation circuit. A pulsating flow obtained by rectifying the high-voltage alternating current output by the power 8 is transmitted to the center electrode 2.

  The electric field generation circuit 8 is a circuit that converts a low-voltage direct current into a high-voltage alternating current using the battery 11 as a power source, and a DC-DC converter 12 that boosts the voltage of the battery 11, for example, about 12 V (volts) to about 300 V to 500 V, for example. The H-bridge circuit 13 that converts the direct current output from the DC-DC converter 12 to alternating current, and the step-up transformer 14 that further boosts the alternating current output from the H-bridge circuit 13 to a higher voltage. The H bridge circuit 13 changes the direct current to an alternating current having a frequency of about 200 kHz to 500 MHz, preferably 100 MHz. Further, the step-up transformer constituted by the step-up transformer 44 has a turn ratio of the primary side winding and the secondary side winding of, for example, 1:10, and the output of the DC-DC converter 12 is about 3 kVp-p to 10 kVp-p. Boost to.

  The first diode 9 has its cathode connected to the signal line 15 of the secondary winding of the step-up transformer 14, that is, the end of the secondary winding not connected to the ground line 16, and its anode connected to the mixer 7. Connected. That is, when a negative high voltage pulse voltage for spark discharge is generated in the ignition coil 6, the first diode 9 is connected to the signal line 15 so as to be opposite to the direction of the current due to the negative high voltage pulse voltage. Connected to. The reverse breakdown voltage of the first diode 9 is set to a voltage exceeding the negative high voltage pulse voltage.

  The second diode 10 has an anode connected to the ground line 16 of the secondary winding of the step-up transformer 14 and a cathode connected to the ground 17, that is, a metal portion of the engine 100. That is, similarly to the first diode 9, when a negative high voltage pulse voltage for spark discharge is generated in the ignition coil 6, the first direction is such that the direction of the current due to the negative high voltage pulse voltage is opposite. The two diodes 10 are connected to the ground line 16. The second diode 10 may have the same electrical characteristics as the first diode 9.

  In such a configuration, at the time of ignition, a spark discharge is generated in the spark plug 1 by the negative high voltage pulse voltage from the ignition coil 6, and an electric field is generated almost simultaneously with the start of the spark discharge or immediately after the start of the spark discharge or immediately before the start of the spark discharge. An electric field is generated around the center electrode 2 and the ground electrode 3 by a pulsating current rectified by the first and second diodes 9 and 10 from the high-voltage alternating current output from the generation circuit 8 to cause the spark discharge and the electric field to react. Thus, the air-fuel mixture in the combustion chamber is rapidly burned by generating plasma in a space including the gap 18 between the center electrode 2 and the ground electrode 3. It should be noted that “immediately after the start of spark discharge” is preferably at the start of induction discharge constituting the spark discharge at the latest.

  Specifically, the spark discharge generated by the spark plug 1 becomes plasma in an electric field, and the flame nucleus at the beginning of flame propagation combustion is larger than ignition by only spark discharge by igniting the mixture with the plasma. In addition, combustion is promoted by generating a large amount of radicals in the combustion chamber.

  This is because the flow of electrons due to the spark discharge and the ions and radicals generated by the spark discharge are vibrated and meandered by the influence of the electric field, resulting in a longer path length and a dramatic increase in the number of collisions with surrounding water and nitrogen molecules. This is due to the increase. Water molecules and nitrogen molecules that have been struck by ions and radicals become OH radicals and N radicals, and the surrounding gas that has been struck by ions and radicals is ionized, in other words, a plasma state. The ignition region for the air-fuel mixture dramatically increases, and the flame kernel that starts the flame propagation combustion also increases.

  As a result, the air-fuel mixture is ignited by the plasma generated by the reaction between the spark discharge and the electric field, so that the ignition region is expanded and the two-dimensional ignition of only the spark plug 1 is changed to the three-dimensional ignition. Therefore, the initial combustion is stabilized, the combustion rapidly propagates into the combustion chamber with the increase of the radicals described above, and the combustion expands at a high combustion rate.

  In this way, when ignition is performed, that is, when a negative high voltage pulse voltage for spark discharge is generated in the ignition coil 6, a current due to the negative high voltage pulse voltage is generated from the ignition coil 6 via the mixer 7. 8, the first diode 9 is connected to the signal line 19 of the ignition coil 6 in a direction opposite to the direction of the current due to the negative high voltage pulse voltage. The ignition coil 6 is kept electrically insulated. Similarly, the second diode 10 prevents the current due to the negative high voltage pulse voltage from flowing to the electric field generation circuit 8 via the ground 17 when a spark discharge occurs in the spark plug 1, thereby causing the ground 17. Similarly, the electric field generating circuit 8 is kept electrically insulated from the ignition coil 6 on the side.

  Therefore, when a current generated by such a spark discharge flows to the secondary winding of the step-up transformer 14 of the electric field generation circuit 8, the current is amplified by the step-up transformer 14 to cause electromagnetic interference. The first diode 9 and the second diode 10 can block the current from entering the electric field generation circuit 8. By preventing electromagnetic interference in this way, it is possible to prevent the operation of the electronic control device that controls the engine 100 and the operations of various electromagnetic sensors mounted on the engine 100 from becoming unstable. it can.

  In addition, this invention is not limited to the above-mentioned embodiment.

  In the above-described embodiment, the case where the negative high voltage pulse voltage is generated in the secondary winding of the ignition coil 6 due to the spark discharge has been described. However, the positive high voltage pulse voltage is generated. Also good. In this case, it goes without saying that the connection direction of the first diode and the second diode is opposite to that in the above-described embodiment.

  As the electric field generation circuit of the above-described embodiment, a circuit that generates a pulsating flow may be used. That is, instead of applying an alternating current to the spark plug, a pulsating voltage such as a pulse voltage is applied to generate an electric field between the center electrode and the ground electrode of the spark plug. In the pulsating flow generation circuit, the direct current supplied from the battery is DC? The voltage is boosted by a DC converter, and a pulsating flow is generated by intermittently applying a high-voltage direct current at a predetermined cycle. In the case of a pulsating flow generator, a switching circuit that is periodically turned on and off is used instead of the H-bridge circuit. By using such a pulsating flow generation circuit, an electric field can be generated between the center electrode and the ground electrode.

  The voltage generation circuit may be configured by connecting the step-up transformer 14 to a high-frequency oscillator. The oscillation frequency of the high frequency oscillator may be equivalent to that described in the above embodiment.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  As an application example of the present invention, it can be used for a spark ignition type internal combustion engine that uses gasoline or liquefied natural gas as fuel and requires spark discharge by an ignition plug for ignition.

DESCRIPTION OF SYMBOLS 1 ... Spark plug 6 ... Ignition coil 8 ... Electric field generation circuit 9 ... 1st diode 10 ... 2nd diode

Claims (2)

An ignition coil that is electrically connected to an ignition plug of a spark ignition internal combustion engine and applies a high voltage to the ignition plug, and an electric field generation circuit that is electrically connected to the ignition plug and generates an electric field in the combustion chamber. An ignition device for a spark ignition internal combustion engine, wherein the spark ignition internal combustion engine generates a plasma by reacting a spark discharge generated in a spark plug with a high voltage and a generated electric field to ignite an air-fuel mixture Because
When a high voltage for spark discharge is generated in the ignition coil, the electric field generating circuit is provided with an insulating holding means that holds the electric field generating circuit in an electrically insulated state with respect to the ignition coil.
Insulating holding means Ri Na by using a diode which is arranged in the opposite direction to the direction of the current tends to flow between the ignition coil and the electric field generating circuit via a signal line connecting the ignition coil to the spark plug,
An ignition device for a spark ignition type internal combustion engine , wherein an electric field generation circuit is an AC voltage generation circuit for generating an AC voltage, and the diode rectifies the AC voltage to generate a pulsating voltage to be applied to a spark plug . An ignition coil that is electrically connected to an ignition plug of a spark ignition internal combustion engine and applies a high voltage to the ignition plug, and an electric field generation circuit that is electrically connected to the ignition plug and generates an electric field in the combustion chamber. An ignition device for a spark ignition internal combustion engine, wherein the spark ignition internal combustion engine generates a plasma by reacting a spark discharge generated in a spark plug with a high voltage and a generated electric field to ignite an air-fuel mixture Because
When a high voltage for spark discharge is generated in the ignition coil, the electric field generating circuit is provided with an insulating holding means that holds the electric field generating circuit in an electrically insulated state with respect to the ignition coil.
The insulation holding means uses a diode arranged in a direction opposite to the direction of the current to flow between the ignition coil and the electric field generating circuit via a signal line connecting the ignition coil to the ignition plug;
An ignition device for a spark ignition type internal combustion engine, wherein the diode is provided between the signal line and the electric field generation circuit, and between the electric field generation circuit and a ground line connected to a metal portion of the internal combustion engine.

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