Ignition system for internal combustion engines

Abstract

To provide a technology for more surely igniting a fuel and early converging residual energy.SOLUTION: An ignition device 1 for an internal combustion engine has: a transformer 20 having a primary coil L1 and a secondary coil L2 electromagnetically connected to each other; an energization control portion 30 for controlling energization to the primary coil L1; a first ignition plug 91 electrically connected between a high pressure-side terminal 21 of the secondary coil L2 and ground; and a second ignition plug 92 electrically connected between a low pressure-side terminal 22 of the secondary coil L2 and the ground. The first ignition plug 91 and the second ignition plug 92 are disposed in the same combustion chamber of the internal combustion engine. Thus, a fuel can be more surely ignited by performing the discharge at two ignition plugs 91, 92. Further, residual energy of the first ignition plug 91 and residual energy of the second ignition plug 92 cancel each other, so that the residual energy can be quickly converged.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ignition device for an internal combustion engine.

Background Art

[0002] In an ignition coil for an internal combustion engine, after a current is passed through the primary coil of the coil assembly to generate a magnetic field and then the current is interrupted, a high voltage is generated in the secondary coil by the self-induction effect. At this time, due to the high voltage generated in the secondary coil, discharge occurs in the spark plug.

[0003] Regarding a conventional ignition device for an internal combustion engine, for example, it is described in Patent Document 1. FIG. 4 shows a simplified circuit diagram of a conventional ignition device 1X for an internal combustion engine similar to that described in Patent Document 1. FIG. 5 shows an example of the potential difference (secondary voltage) between both ends of the secondary coil of such an ignition device 1X for an internal combustion engine.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional ignition device 1X for an internal combustion engine as shown in FIGS. 4 and 5, the igniter Ig is turned ON to supply a voltage from the power source Ba to the primary coil Co1 (energization period T1). After supplying the voltage to the primary coil Co1 for a certain period of time, the igniter Ig is turned OFF. Then, due to the self-induction effect, a high voltage is generated in the secondary coil Co2 in the opposite direction to the energization period T1, and discharge occurs in the spark plug Pg (discharge period T2).

[0006] During discharge, charge accumulates in the capacitive components around the spark plug Pg. As a result, as shown in Figure 5, during the standby period T3 after discharge, this residual energy causes a problem in which the convergence of the secondary voltage takes time.

[0007] Furthermore, in recent years, there has been a search for flame-retardant fuels such as hydrogen, which burns more easily than conventional fuels, and ammonia, which burns less easily than conventional fuels. There is a need for technology that can reliably ignite multiple types of fuels with different ignition ease and combustion speeds when mixed together.

[0008] The objective of this invention is to provide a technology that enables more reliable ignition of fuel and accelerates the release of residual energy. [Means for solving the problem]

[0009] To solve the above problems, the first invention of this application provides an ignition device for an internal combustion engine, comprising: a transformer having an electromagnetically coupled primary coil and a secondary coil; a power supply control unit that controls the supply of power to the primary coil; a first spark plug electrically connected between the high-voltage terminal of the secondary coil and ground; and a second spark plug electrically connected between the low-voltage terminal of the secondary coil and ground, wherein the first spark plug and the second spark plug are arranged in the same combustion chamber of the internal combustion engine. The transformer, the first spark plug, and the second spark plug are provided in a one-to-one ratio for each of the combustion chambers of the internal combustion engine, and the circuit consisting of the first spark plug, the second spark plug, and the secondary coil does not include any element that prevents the flow of current in the opposite direction to the discharge of the first and second spark plugs. .

[0010] The second invention of this application is an ignition device for an internal combustion engine according to the first invention, wherein the fuel gas introduced into the combustion chamber is a mixed gas obtained by mixing multiple types of fuel.

[0011] The third invention of this application is an ignition device for an internal combustion engine according to the second invention, wherein the fuel gas introduced into the combustion chamber contains hydrogen.

[0012] The fourth invention of this application is an ignition device for an internal combustion engine according to the second or third invention, wherein the fuel gas introduced into the combustion chamber includes a flame-retardant fuel.

[0013] The fifth invention of this application is an ignition device for an internal combustion engine according to the fourth invention, wherein the flame-retardant fuel is ammonia.

[0014] The sixth invention of this application is an ignition device for an internal combustion engine, comprising: an electromagnetically coupled primary coil; a transformer having two secondary coils; a current control unit for controlling the supply of current to the primary coil; a first spark plug electrically connected between the high-voltage terminal of one of the secondary coils and ground; a second spark plug electrically connected between the low-voltage terminal of one of the secondary coils and ground; a third spark plug electrically connected between the high-voltage terminal of the other secondary coil and ground; and a fourth spark plug electrically connected between the low-voltage terminal of the other secondary coil and ground, wherein the first spark plug, the second spark plug, the third spark plug, and the fourth spark plug are arranged in the same combustion chamber of the internal combustion engine. [Effects of the Invention]

[0015] According to the first to sixth inventions of this application, reliable ignition of the fuel is achieved, and residual energy can be quickly contained.

[0016] The second to fifth inventions of this application are particularly useful because it is necessary to ensure more reliable ignition of the fuel. [Brief explanation of the drawing]

[0017] [Figure 1] This is a circuit diagram of an ignition system for an internal combustion engine according to the first embodiment. [Figure 2] This figure shows an example of a secondary voltage waveform in an ignition system for an internal combustion engine according to the first embodiment. [Figure 3] This is a circuit diagram of an ignition system for an internal combustion engine according to the second embodiment. [Figure 4] This is a circuit diagram of a conventional ignition system for internal combustion engines. [Figure 5] This figure shows an example of a secondary voltage waveform in a conventional ignition system for internal combustion engines. [Modes for carrying out the invention]

[0018] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

[0019] <1. First Embodiment> <1-1. Configuration of Ignition Device for Internal Combustion Engine> The configuration of an ignition device 1 for an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of the ignition device 1 for an internal combustion engine according to the first embodiment. In FIG. 1, the detailed circuit on the primary side is omitted.

[0020] The ignition device 1 for an internal combustion engine in the present embodiment is, for example, a device that is mounted on the vehicle body of a vehicle such as an automobile and applies a high voltage for generating a spark discharge to the ignition plugs 91 and 92 for an internal combustion engine. As shown in FIG. 1, the ignition device 1 for an internal combustion engine includes a transformer 20, an energization control unit 30, a first ignition plug 91, and a second ignition plug 92.

[0021] When the ignition device 1 for an internal combustion engine is used in a multi-cylinder internal combustion engine, the battery 31 and the ECU 32, which will be described later, of the energization control unit 30 may be common to a plurality of cylinders. On the other hand, the transformer 20, the igniter 33, which will be described later, of the energization control unit 30, the first ignition plug 91, and the second ignition plug 92 are provided for each cylinder. For example, in a four-cylinder internal combustion engine, one battery 31 and one ECU 32, and four sets of transformers 20, igniters 33, first ignition plugs 91, and second ignition plugs 92 are provided.

[0022] In an internal combustion engine using the ignition device 1 of this embodiment, the combustion gas introduced into the combustion chamber of each cylinder is a mixed gas composed of multiple types of fuel. This mixed gas includes, for example, hydrogen gas and ammonia, a non-flammable fuel. Hydrogen gas is more easily ignited and burns faster than conventional fuels such as gasoline. On the other hand, ammonia gas is more difficult to ignite and burns slower than conventional fuels such as gasoline. When using a combustion gas composed of fuels with different ignition ease and combustion speeds, it is necessary to perform ignition more reliably and to focus the residual energy around the spark plug more quickly than with conventional ignition devices.

[0023] The transformer 20 has an electromagnetically coupled primary coil L1 and secondary coil L2. The secondary coil L2 has more turns than the primary coil L1. The secondary coil L2 has a high-voltage terminal 21 and a low-voltage terminal 22 at both ends.

[0024] The power supply control unit 30 controls the supply of power to the primary coil L1. The power supply control unit 30 includes a battery 31, an ECU (Engine Control Unit) 32, and an igniter 33.

[0025] The battery 31 is a power supply device (storage battery) capable of charging and discharging DC power. In this embodiment, the battery 31 is electrically connected to the primary coil L1 and igniter 33 of the transformer 20. The battery 31 supplies a DC voltage to the primary coil L1 and igniter 33 of the transformer 20.

[0026] The ECU32 is an existing computer that comprehensively controls the vehicle's transmission, airbag operation, and other functions. The ECU32 outputs an ignition signal to the igniter 33 and controls the ON / OFF operation of the igniter 33.

[0027] The igniter 33 controls the energization of the primary coil L1. The igniter 33 is a switching element such as an IGBT (Insulated Gate Bipolar Transistor). The igniter 33 switches ON / OFF according to the ignition signal supplied from the ECU 32, controlling the energization of the primary coil L1.

[0028] The first spark plug 91 and the second spark plug 92 are located inside the combustion chamber of the internal combustion engine and are devices that enable ignition in the combustion chamber of the internal combustion engine. The first spark plug 91 and the second spark plug 92 have the same plug specifications and plug gap. The first spark plug 91 and the second spark plug 92 are located at a distance from each other within a single combustion chamber.

[0029] The first spark plug 91 is electrically connected between the high-voltage terminal 21 of the secondary coil L2 of the transformer 20 and ground. That is, one end of the first spark plug 91 is connected to the high-voltage terminal 21, and the other end of the first spark plug 91 is grounded.

[0030] The second spark plug 92 is electrically connected between the low-voltage terminal 22 of the secondary coil L2 of the transformer 20 and ground. That is, one end of the second spark plug 92 is connected to the low-voltage terminal 22, and the other end of the second spark plug 92 is grounded.

[0031] When the igniter 33 turns ON in accordance with the ignition signal from the ECU 32, a voltage is applied across the primary coil L1, and a current is generated in the primary circuit. This creates a magnetic flux inside the transformer 20. Subsequently, when the igniter 33 turns OFF in accordance with the ignition signal from the ECU 32, electromagnetic induction by the magnetic flux formed inside the transformer 20 induces a high voltage across the secondary coil L2, opposite to the voltage supplied by the battery 31. As a result, the high-voltage terminal 21 becomes significantly negative relative to the low-voltage terminal 22.

[0032] As a result, the high-voltage terminal 21 connected to the first spark plug 91 becomes a large negative potential, while the low-voltage terminal 22 connected to the second spark plug 92 becomes a large positive potential. This causes a discharge to occur in the gap between the first spark plug 91 and the second spark plug 92, generating a spark. This ignites the fuel filled in the internal combustion engine.

[0033] <1-2. Changes in secondary voltage in ignition systems for internal combustion engines> Next, with reference to Figure 2, the change in the secondary voltage in the ignition system 1 for an internal combustion engine of this embodiment will be explained. Figure 2 is a diagram showing an example of the secondary voltage waveform in the ignition system 1 for an internal combustion engine of this embodiment. Specifically, Figure 2 is the simulation result for the ignition system 1 for an internal combustion engine. In the following, the secondary voltage will be described as the voltage at the high-voltage side terminal 21 of the secondary coil L2 as the first plug voltage V1, and the voltage at the low-voltage side terminal 22 of the secondary coil L2 as the second plug voltage V2.

[0034] In an internal combustion engine, the intake, compression, combustion, and exhaust cycle is performed by opening and closing the intake and exhaust valves and discharging the spark plugs in accordance with the rotation of the crankshaft. The ignition system 1 for the internal combustion engine burns the compressed fuel gas in the combustion chamber by discharging the spark plugs near the top dead center of compression. The ignition system 1 for the internal combustion engine performs the discharge of the spark plugs 91 and 92, Energization period T1: Energization of primary coil L1 Discharge period T2: Discharge at spark plugs 91 and 92 Waiting period T3: Residual energy recovery This is done in accordance with the movement of the piston.

[0035] First, we will explain the change in the secondary voltage Vx in the conventional internal combustion engine ignition system 1X shown in Figure 4, with reference to Figure 5. In the internal combustion engine ignition system 1X, the spark plug Pg is connected between the high-voltage terminal of the secondary coil Co2 and ground. Hereafter, the voltage at the high-voltage terminal of the secondary coil Co2 will be referred to as the secondary voltage Vx. That is, the secondary voltage Vx is the voltage across both ends of the spark plug Pg. Immediately after the start of use of the internal combustion engine ignition system 1, that is, before the energization period T1, the secondary voltage Vx is 0 [V].

[0036] When the energizing period T1 begins and current is supplied to the primary coil Co1, a voltage (ON voltage) is generated in the secondary coil Co2 as voltage is supplied to the primary coil Co1. As the current to the primary coil Co1 continues, the secondary voltage Vx gradually decreases from the ON voltage as magnetic flux is formed inside the transformer.

[0037] When the energizing period T1 ends and the power supply to the primary coil Co1 is cut off, a high voltage opposite to (negative) the ON voltage is generated in the secondary coil Co2. This applies a high voltage to the spark plug Pg, causing a discharge in the gap of the spark plug Pg (discharge period T2). Subsequently, the magnetic flux formed in the transformer 20 weakens with the discharge, and the absolute value of the secondary current (the current flowing through the secondary coil Co2 and the spark plug Pg) gradually decreases. This ends the discharge in the spark plug Pg.

[0038] During the discharge period T2, current flows through the spark plug Pg, causing charge to accumulate in the capacitive components around the spark plug Pg. Specifically, positive charge accumulates on the ground side of the spark plug Pg, and negative charge accumulates on the secondary coil Co2 side.

[0039] Therefore, during the standby period T3, the secondary voltage Vx will remain at a negative potential for a while due to the residual energy accumulated in the parasitic capacitance around the spark plug Pg. The secondary voltage Vx will converge to 0[V] as the residual energy converges.

[0040] Next, the changes in the first spark plug voltage V1 and the second spark plug voltage V2 in the ignition system 1 for internal combustion engines of this embodiment will be explained with reference to Figure 2.

[0041] First, immediately after the start of use of the internal combustion engine ignition system 1, that is, before the energizing period T1, there is no charge accumulation in the secondary coil L2, the first spark plug 91, or the second spark plug 92, and the potential in all of these circuits is 0[V]. That is, the voltage of the first plug V1 and the voltage of the second plug V2 are also 0[V].

[0042] When the energizing period T1 begins and current is supplied to the primary coil L1, a potential difference is generated across the secondary coil L2 as voltage is supplied to the primary coil L1. Here, if the voltage generated in the secondary coil L2 immediately after the start of energizing is 2*Von[V], then since the other end of the first spark plug 91 and the other end of the second spark plug 92 are grounded and have a voltage of 0[V], the voltage of the first plug V1 becomes Von[V] and the voltage of the second plug V2 becomes -Von[V]. Thus, the voltage generated at the beginning of the energizing period T1 is called the ON voltage.

[0043] As the primary coil L1 remains energized, the potential difference across the secondary coil L2 gradually decreases from 2*Von[V] as a magnetic flux is formed within the transformer 20. Accordingly, the absolute values ​​of the first plug voltage V1 and the second plug voltage V2 also gradually decrease from Von[V].

[0044] When the energizing period T1 ends and the power supply to the primary coil L1 is cut off, a high voltage opposite to the ON voltage is generated in the secondary coil L2. As a result, a high negative voltage is applied to the first spark plug 91, causing a discharge in the gap of the first spark plug 91. Also, a high positive voltage is applied to the second spark plug 92, causing a discharge in the gap of the second spark plug 92 (discharge period T2).

[0045] Here, let the maximum voltage generated in the secondary coil L2 during the discharge period T2 be -2*Vd[V]. Therefore, the first plug voltage V1 is -Vd[V] and the second plug voltage V2 is Vd[V].

[0046] During the discharge period T2, current flows through the first spark plug 91 and the second spark plug 92, causing charge to accumulate in the capacitive components around the first spark plug 91 and the second spark plug 92. Specifically, a positive charge accumulates on the other end (ground side) of the first spark plug 91, and a negative charge accumulates on one end (high-voltage terminal 21 side). On the other hand, a negative charge accumulates on the other end (ground side) of the second spark plug 92, and a positive charge accumulates on one end (low-voltage terminal 22 side).

[0047] When the discharge period T2 ends and the standby period T3 begins, the charges accumulated in the capacitive component around the first spark plug 91 and the charges accumulated in the capacitive component around the second spark plug 92 move in such a way that they cancel each other out. As a result, the residual energy accumulated in the parasitic capacitance around the first spark plug 91 and the residual energy accumulated in the parasitic capacitance around the second spark plug 92 are both dissipated.

[0048] As mentioned above, the first spark plug 91 and the second spark plug 92 have the same plug specifications and plug gap. Therefore, the residual energy accumulated in the parasitic capacitance around the first spark plug 91 and the residual energy accumulated in the parasitic capacitance around the second spark plug 92 are approximately equal. As a result, the residual energies of both cancel each other out in a balanced manner.

[0049] Furthermore, due to the transfer of charge between the parasitic capacitance around the first spark plug 91 and the parasitic capacitance around the second spark plug 92, a current temporarily flows through the secondary coil L2, causing the first plug voltage V1 and the second plug voltage V2 to temporarily oscillate.

[0050] Due to this charge transfer, the residual energy accumulated in the parasitic capacitance around the first spark plug 91 and the residual energy accumulated in the parasitic capacitance around the second spark plug 92 are largely dissipated and reduced to a small amount immediately after the end of the discharge period T2. The remaining residual energy then causes the voltage of the first plug V1 to become a relatively small negative potential, and the voltage of the second plug V2 to become a relatively small positive potential. Subsequently, both the voltage of the first plug V1 and the voltage of the second plug V2 converge to 0[V].

[0051] In the case of a conventional internal combustion engine ignition system 1X shown in Figures 4 and 5, where there is only one spark plug, a large amount of residual energy remains even during the standby period T3. In contrast, in the internal combustion engine ignition system 1 of this embodiment, two spark plugs 91 and 92 are connected to one secondary coil L2, allowing the residual energy to be quickly concentrated.

[0052] It should be noted that a D-DLI (Distributor Less Ignition with Double-ended coil) system having a circuit configuration equivalent to the ignition device 1 for internal combustion engines of this embodiment is known. In the D-DLI system, the first spark plug 91 and the second spark plug 92 are arranged in the combustion chambers of two cylinders that are half a cycle apart. That is, the second spark plug 92 is arranged in the cylinder opposite the cylinder in which the first spark plug 91 is located.

[0053] Therefore, when the first spark plug 91 attempts to discharge near top dead center of compression, the second spark plug 92 discharges near top dead center of exhaust. At this time, near top dead center of compression, the pressure in the combustion chamber is high, the voltage required for the first spark plug 91 to discharge is high, and the residual energy after discharge is also high. On the other hand, near top dead center of exhaust, the pressure in the combustion chamber is low, the voltage required for the second spark plug 92 to discharge is also high, and the residual energy after discharge is low.

[0054] Therefore, even if the residual energy around the first spark plug 91 and the parasitic capacitance around the second spark plug 92 cancel each other out after discharge, there is a problem that some residual energy remains around the first spark plug 91.

[0055] In contrast, in the ignition system 1 for internal combustion engines of this embodiment, two spark plugs 91 and 92 are connected to one secondary coil L2, which allows for rapid convergence of residual energy.

[0056] Furthermore, in the ignition system 1 for internal combustion engines of this embodiment, both the first spark plug 91 and the second spark plug 92 are located in the same combustion chamber. Therefore, discharge occurs simultaneously at two locations in the combustion chamber at the same time. As a result, ignition can be more reliably achieved even when mixing multiple types of fuels with different ignition ease and combustion speeds. Consequently, it is possible to use mixed fuels that include hydrogen, which burns more easily than conventional fuels, or flame-retardant fuels such as ammonia, which burns less easily than conventional fuels.

[0057] <2. Second Embodiment> Next, the configuration of the ignition device 1A for an internal combustion engine, which is a second embodiment of the present invention, will be described with reference to the drawings. Figure 3 is a circuit diagram of the ignition device 1A for an internal combustion engine according to the second embodiment.

[0058] As shown in Figure 3, the ignition system 1A for an internal combustion engine includes a transformer 20A, a power supply control unit 30A, a first spark plug 91A, a second spark plug 92A, a third spark plug 93A, and a fourth spark plug 94A. The power supply control unit 30A is equivalent to the power supply control unit 30 in the first implementation, so its description is omitted.

[0059] Transformer 20A has an electromagnetically coupled primary coil L1A, a first secondary coil L2A, and a second secondary coil L3A. Both the first secondary coil L2A and the second secondary coil L3A have more turns than the primary coil L1A. The first secondary coil L2A has a first high-voltage terminal 21A and a first low-voltage terminal 22A at both ends. The second secondary coil L3A has a second high-voltage terminal 23A and a second low-voltage terminal 24A at both ends.

[0060] The first spark plug 91A, the second spark plug 92A, the third spark plug 93A, and the fourth spark plug 94A are located inside the combustion chamber of an internal combustion engine and are devices that enable ignition within the combustion chamber. The first spark plug 91A and the second spark plug 92A have the same plug specifications and plug gap. Similarly, the third spark plug 93A and the fourth spark plug 94A have the same plug specifications and plug gap. The first spark plug 91A, the second spark plug 92A, the third spark plug 93A, and the fourth spark plug 94A are arranged at intervals within a single combustion chamber.

[0061] The first spark plug 91A is electrically connected between the first high-voltage terminal 21A of the first secondary coil L2A of the transformer 20A and ground. That is, one end of the first spark plug 91A is connected to the first high-voltage terminal 21A, and the other end of the first spark plug 91A is grounded.

[0062] The second spark plug 92A is electrically connected between the first low-voltage terminal 22A of the first secondary coil L2A of the transformer 20A and ground. That is, one end of the second spark plug 92A is connected to the first low-voltage terminal 22A, and the other end of the second spark plug 92A is grounded.

[0063] The third spark plug 93A is electrically connected between the second high-voltage terminal 23A of the second secondary coil L3A of the transformer 20A and ground. That is, one end of the third spark plug 93A is connected to the second high-voltage terminal 23A, and the other end of the third spark plug 93A is grounded.

[0064] The fourth spark plug 94A is electrically connected between the second low-voltage terminal 24A of the second secondary coil L3A of the transformer 20A and ground. That is, one end of the fourth spark plug 94A is connected to the second low-voltage terminal 24A, and the other end of the fourth spark plug 94A is grounded.

[0065] When the igniter 33 turns ON in accordance with the ignition signal from the ECU 32, a voltage is applied across the primary coil L1A, generating a current in the primary circuit. This creates a magnetic flux within the transformer 20A. Subsequently, when the igniter 33 turns OFF in accordance with the ignition signal from the ECU 32, electromagnetic induction by the magnetic flux formed within the transformer 20A induces a high voltage opposite to the voltage supplied by the battery 31 across the first secondary coil L2A and the second secondary coil L3A. As a result, the first high-voltage terminal 21A becomes significantly negative relative to the first low-voltage terminal 22A, and the second high-voltage terminal 23A becomes significantly negative relative to the second low-voltage terminal 35A.

[0066] As a result, the first high-voltage terminal 21A, connected to the first spark plug 91A, becomes a large negative potential, while the first low-voltage terminal 22A, connected to the second spark plug 92A, becomes a large positive potential. This causes a discharge to occur in the gap between the first spark plug 91A and the second spark plug 92A, generating a spark. This ignites the fuel filled in the internal combustion engine.

[0067] Simultaneously, the second high-voltage terminal 23A, connected to the third spark plug 93A, becomes a large negative potential, while the second low-voltage terminal 24A, connected to the fourth spark plug 94A, becomes a large positive potential. As a result, a discharge occurs in the gap between the third spark plug 93A and the fourth spark plug 94A, generating a spark. This ignites the fuel filled in the internal combustion engine.

[0068] In such an internal combustion engine ignition system 1A, when the discharge period T2 ends and the standby period T3 begins, the charges accumulated in the capacitive component around the first spark plug 91A and the charges accumulated in the capacitive component around the second spark plug 92A move in such a way that they cancel each other out. As a result, the residual energy accumulated in the parasitic capacitance around the first spark plug 91A and the residual energy accumulated in the parasitic capacitance around the second spark plug 92A are both dissipated.

[0069] Furthermore, when the discharge period T2 ends and the standby period T3 begins, the charges accumulated in the capacitive component around the third spark plug 93A and the charges accumulated in the capacitive component around the fourth spark plug 94A move in such a way that they cancel each other out. As a result, the residual energy accumulated in the parasitic capacitance around the third spark plug 93A and the residual energy accumulated in the parasitic capacitance around the fourth spark plug 94A are both dissipated.

[0070] As mentioned above, the first spark plug 91A and the second spark plug 92A have the same plug specifications and plug gap. Therefore, the residual energy accumulated in the parasitic capacitance around the first spark plug 91A and the residual energy accumulated in the parasitic capacitance around the second spark plug 92A are approximately equal. As a result, the residual energies of both cancel each other out in a balanced manner.

[0071] Furthermore, the third spark plug 93A and the fourth spark plug 94A have the same plug specifications and plug gap. Therefore, the residual energy accumulated in the parasitic capacitance around the third spark plug 93A and the residual energy accumulated in the parasitic capacitance around the fourth spark plug 94A are almost equal. As a result, the residual energies of both cancel each other out in a balanced manner.

[0072] Due to this charge transfer, the residual energy accumulated in the parasitic capacitance around each of the four spark plugs 91A, 92A, 93A, and 94A is largely dissipated and reduced to a negligible amount immediately after the end of the discharge period T2. In other words, in the ignition system 1 for internal combustion engines of this embodiment, the residual energy can be quickly concentrated for each of the spark plugs 91A, 92A, 93A, and 94A because the two spark plugs 91A and 92A are connected to one first secondary coil L2A, and the two spark plugs 93A and 94A are connected to one second secondary coil L3A.

[0073] In the ignition system 1A for an internal combustion engine of this embodiment, a larger number of spark plugs 91A, 92A, 93A, and 94A are arranged in the same combustion chamber compared to the ignition system 1 for an internal combustion engine of the first embodiment. This increases the number of discharge points, i.e., heat-generating points.

[0074] As a result, ignition becomes easier within the combustion chamber. Therefore, even when mixing multiple types of fuels with different ignition ease and combustion speeds, ignition can be more reliably achieved. Consequently, mixed fuels containing hydrogen, which burns more easily than conventional fuels, or flame-retardant fuels such as ammonia, which burns less easily than conventional fuels, can be used. In particular, even if the mixing ratio of mixed fuels is uneven depending on the location within the combustion chamber, reliable ignition can be achieved. Furthermore, the increased number of heat-generating points can accelerate the combustion speed within the combustion chamber.

[0075] <3. Variant> Although exemplary embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above.

[0076] The ignition device for internal combustion engines of the present invention may be installed not only in vehicles such as automobiles, but also in various devices such as generators and industrial machinery, and is used to generate an electric spark at the spark plug of an internal combustion engine to ignite the fuel.

[0077] The detailed shape and structure of the ignition device for the internal combustion engine described above may be modified as appropriate without departing from the spirit of the present invention. Furthermore, the elements that appear in the above embodiments and modifications may be combined as appropriate without creating any inconsistencies. [Explanation of Symbols]

[0078] 1.1A Ignition system for internal combustion engines 20,20A transformer 21 High-voltage side terminal 22 Low-voltage side terminal 21A First high-voltage terminal 22A First Low Voltage Terminal 23A Second high-voltage terminal 24A Second Low-Voltage Terminal 30 Power supply control unit 91,91A First spark plug 92,92A Second spark plug 93A Third Spark Plug 94A Spark Plug No. 4 L1, L1A Primary coil L2 Secondary Coil L2A Primary Secondary Coil L3A Secondary Coil

Claims

1. An ignition system for an internal combustion engine, A transformer having an electromagnetically coupled primary coil and a secondary coil, A current supply control unit that controls the supply of current to the primary coil, A first spark plug is electrically connected between the high-voltage terminal of the secondary coil and ground, A second spark plug is electrically connected between the low-voltage terminal of the secondary coil and ground, It has, The first spark plug and the second spark plug are located in the same combustion chamber of the internal combustion engine. The transformer, the first spark plug, and the second spark plug are provided in a one-to-one ratio for each of the combustion chambers of the internal combustion engine. An ignition system for an internal combustion engine in which the circuit comprising the first spark plug, the second spark plug, and the secondary coil does not include an element that prevents the flow of current in the opposite direction to the discharge of the first spark plug and the second spark plug.

2. An ignition device for an internal combustion engine according to claim 1, An ignition device for an internal combustion engine, wherein the fuel gas introduced into the combustion chamber is a mixed gas composed of multiple types of fuel.

3. An ignition device for an internal combustion engine according to claim 2, An ignition device for an internal combustion engine, wherein the fuel gas introduced into the combustion chamber contains hydrogen.

4. An ignition device for an internal combustion engine according to claim 2 or claim 3, The fuel gas introduced into the combustion chamber contains a flame-retardant fuel in an ignition device for an internal combustion engine.

5. An ignition device for an internal combustion engine according to claim 4, The aforementioned flame-retardant fuel is ammonia; this is an ignition system for an internal combustion engine.

6. An ignition system for an internal combustion engine, A transformer having an electromagnetically coupled primary coil and two secondary coils, A current supply control unit that controls the supply of current to the primary coil, One of the secondary coils has a first spark plug that is electrically connected between the high-voltage terminal and ground, A second spark plug is electrically connected between the low-voltage terminal of the secondary coil and ground, A third spark plug is electrically connected between the high-voltage terminal of the other secondary coil and ground, A fourth spark plug is electrically connected between the low-voltage terminal of the other secondary coil and ground, It has, The first spark plug, the second spark plug, the third spark plug, and the fourth spark plug are arranged in the same combustion chamber of the internal combustion engine, and this is an ignition system for an internal combustion engine.

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