CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

Abstract

Control device (1) for an internal combustion engine (100) comprising the following: an ignition control unit (83) that controls the excitation of a first ignition coil (300a) and a second ignition coil (300b), each of which provides electrical energy to a spark plug (200) that discharges into a cylinder (150) of an internal combustion engine (100) to ignite a fuel; and a discharge quantity detection unit (360) that detects a voltage between the electrodes of the spark plug (200), wherein the ignition control unit (83), after the ignition control unit (83) has discharged the spark plug (200) using the electrical energy of the first ignition coil (300a), estimates a voltage that can be supplied to the spark plug (200) from the first ignition coil (300a), and controls the excitation of the second ignition coil (300b) such that the electrical energy of the second ignition coil (300b) is supplied to the spark plug (200) when a difference between the estimated supplyable voltage and a voltage required to maintain the discharge of the spark plug (200) based on the voltage detected by the discharge quantity detection unit (360) is less than or equal to a predetermined threshold.

Description

Technical field

[0001] The present invention relates to a control device for an internal combustion engine. Technical background

[0002] In recent years, in order to improve the fuel efficiency of a vehicle, a control device for an internal combustion engine has been developed that uses a technique of working with an air / fuel mixture that is leaner than a theoretical air / fuel ratio, or a technique of capturing a portion of exhaust gas after combustion in such a way that the portion is re-intaked.

[0003] In this type of control device of an internal combustion engine, the amount of fuel or air in a combustion chamber deviates from a theoretical value, which is why a fuel ignition failure by a spark plug is likely to occur.

[0004] PTL 1 discloses an ignition device for an internal combustion engine which sets the number of ignitions in a cycle based on an operating condition of an internal combustion engine, determines the ignition in a cylinder of the internal combustion engine and, based on the number of ignitions, when the ignition is determined, prevents the number of subsequent ignitions.

[0005] Furthermore, PTL 2 discloses a system and method for providing ignition spark to an engine, in which a single conductor can output an ignition signal that specifies the desired ignition timing for multiple ignition coils. More precisely, PTL 2 proposes using two ignition coils per spark plug and controlling their charging time via a single conductor. Additionally, different pulse widths are encoded to distinguish between the two coils, or alternatively, two conductors are used, with one conductor capable of sending commands to multiple coils.

[0006] In PTL 3, an ignition device is also described in which, in particular, two ignition coils are used sequentially to supply a single spark plug, wherein a first ignition coil generates a main ignition and a second ignition coil, called the main ignition, extends it using stored energy from an amplifier circuit.

[0007] PTL 4 further discloses a system and a method for providing an ignition spark in spark-ignition internal combustion engines, particularly for engines operating with lean or dilute air-fuel mixtures. Two ignition coils are controlled by means of two separate ignition coil commands via a single control line to reduce wiring complexity, while the system is simultaneously configured to ignore faulty commands, especially if previously assigned control pulses have been identified as faulty or missing.

[0008] PTL 5 further describes a method for controlling a spark plug with a first and a second ignition coil, which is intended to reduce the effort required to generate a discharge across the spark gap. Triggered by a start signal, the primary winding of the first ignition coil and, after a delay, the primary winding of the second ignition coil are charged by supplying direct current. During the charging of each primary winding, the corresponding secondary windings are blocked, and the primary current supplied to the primary windings is measured. After a predefined duration, the primary winding of the first ignition coil and, after a delay, the primary winding of the second ignition coil are discharged, and the secondary current flowing through the spark plug is measured.Subsequently, the charging of the primary windings of the first and second ignition coils is initiated alternately when the secondary current falls below a predefined threshold, and the primary windings are discharged alternately when the primary current reaches an upper threshold. The preceding steps are then repeated until the duration of the discharge between two spark plug electrodes reaches a predetermined value.

[0009] The content of PTL 6 further relates to an inductive ignition system for a gasoline engine, in particular a four-stroke engine, with an even number of spark plugs, which are arranged in the gasoline engine and controlled by a control unit such that one or more pairs of two spark plugs each are simultaneously in an exhaust stroke of a cylinder of the gasoline engine. Each such pair of spark plugs is assigned two ignition coils with a primary winding and a secondary winding, which together cause a prolonged spark discharge or a sequence of several individual sparks simultaneously at both spark plugs of a pair during a specific period of time in each engine cycle. List of prior art patent literature PTL 1: JP 2017-172557 A PTL 2: US 2014 / 0 102 412 A1 PTL 3: DE 11 2015 001 714 T5 PTL 4: DE 10 2016 113 298 A1 PTL 5: DE 10 2013 102 529 A1 PTL 6: DE 10 2012 106 158 A1 Summary of the invention: Technical problem

[0010] In the ignition device of an internal combustion engine disclosed in PTL 1, a large number of ignitions can be set, depending on the operating conditions of the internal combustion engine, to avoid ignition failure. In this case, it is necessary to provide many ignition coils to supply sufficient electrical energy to each spark plug. However, increasing the number of ignition coils leads to an increase in the size and cost of the ignition device, which is not desirable.

[0011] Therefore, the present invention has been made in consideration of the above problems, and one object of it is to improve the ignitability of a fuel by a spark plug, while preventing an increase in the number of ignition coils. Solution to the problem

[0012] According to one aspect of the present invention, a control device for an internal combustion engine is provided, comprising: an ignition control unit that controls the excitation of a first ignition coil and a second ignition coil, each of which provides electrical energy to a spark plug that discharges into a cylinder of an internal combustion engine to ignite a fuel;and a discharge quantity detection unit that detects a voltage between the electrodes of the spark plug, wherein, after the ignition control unit has discharged the spark plug using the electrical energy of the first ignition coil, the ignition control unit estimates a voltage that can be supplied to the spark plug from the first ignition coil and controls the excitation of the second ignition coil such that the electrical energy of the second ignition coil is supplied to the spark plug when a difference between the estimated supplyable voltage and a voltage required to maintain the discharge of the spark plug, based on the voltage detected by the discharge quantity detection unit, is less than or equal to a predetermined threshold. Advantageous effects of the invention

[0013] According to the present invention, it is possible to improve the ignitability of a fuel by the spark plug, while preventing an increase in the number of ignition coils. Brief description of the drawings Fig. Figure 1 is a diagram illustrating the main configurations of an internal combustion engine and a control device for an internal combustion engine according to one embodiment. Fig. Figure 2 is an enlarged partial view illustrating a spark plug. Fig. Figure 3 is a functional block diagram illustrating a functional configuration of the control device. Fig. Figure 4 is a diagram illustrating an electrical circuit containing an ignition coil. Fig. Figure 5 is a schematic diagram illustrating an example of a conventional multiple discharge procedure. Fig. Figure 6 is a schematic diagram illustrating an example of a multiple discharge method according to the embodiment. Fig. Figure 7 is an example of a flowchart illustrating a method for controlling the spark plug by an ignition control unit according to the embodiment. Fig. Figure 8 is an example of a flowchart illustrating an excitation control process performed on an ignition coil from which electrical energy is first released. Fig. Figure 9 is an example of a flowchart illustrating the excitation control process carried out for ignition coils, from which the electrical energy is released in the second repetition and in subsequent repetitions. Description of the embodiments

[0014] The following describes a control device for an internal combustion engine according to an embodiment of the present invention.

[0015] In the following, a control device 1, which is a form of control device for an internal combustion engine, is described according to the embodiment.

[0016] In this embodiment, an example is described in which the control device 1 controls the discharge (ignition) of a spark plug 200, which is provided in each cylinder 150 of an internal combustion engine 100 with four cylinders.

[0017] In the following embodiment, a combination of some or all configurations of the internal combustion engine 100 and some or all configurations of the control device 1 shall be referred to as the control device 1 of the internal combustion engine 100. [Internal combustion engine]

[0018] Fig. Figure 1 is a diagram illustrating the main configurations of the internal combustion engine 100 and an ignition device for an internal combustion engine.

[0019] Fig. Figure 2 is an enlarged partial view illustrating electrodes 210 and 220 of spark plug 200.

[0020] In the internal combustion engine 100, air drawn in from outside flows through an air cleaning device 110, an inlet pipe 111, and an inlet distributor pipe 112, and flows into each cylinder 150 when an inlet valve 151 is open. The amount of air flowing into each cylinder 150 is controlled by a throttle valve 113, and the amount of air controlled by the throttle valve 113 is measured by a flow sensor 114.

[0021] The throttle valve 113 is equipped with a throttle valve opening degree sensor 113a, which detects the opening degree of the throttle valve. The opening degree information of the throttle valve 113, detected by the throttle valve opening degree sensor 113a, is output to the control device (electronic control unit: ECU) 1.

[0022] The throttle valve 113 uses an electronic throttle valve driven by an electric motor. However, any valve can be used as long as the airflow rate can be properly adjusted.

[0023] The temperature of a gas flowing into each cylinder 150 is detected by an intake air temperature sensor 115.

[0024] A crank angle sensor 121 is provided radially outside a ring gear 120, which is attached to a crankshaft 123. The crank angle sensor 121 detects a rotation angle of the crankshaft 123. In this embodiment, the crank angle sensor 121 detects, for example, the rotation angle of the crankshaft 123 every 10° and for each combustion cycle.

[0025] A water temperature sensor 122 is provided in a cooling water jacket (not illustrated) of the cylinder head. The water temperature sensor 122 detects the temperature of the cooling water of the internal combustion engine 100.

[0026] Furthermore, the vehicle includes an accelerator pedal position sensor (APS) 126, which detects the amount of displacement (amount of depression) of an accelerator pedal 125. The accelerator pedal position sensor 126 detects a torque requested by a driver. The torque requested by the driver, detected by the accelerator pedal position sensor 126, is output to the control device 1, which is described later. The control device 1 controls the throttle valve 113 based on this requested torque.

[0027] Fuel stored in a fuel tank 130 is drawn in by a fuel pump 131 and pressurized. It then flows through a fuel line 133, which includes a pressure regulator 132, and is directed to a fuel injector 134. The fuel dispensed by the fuel pump 131 is adjusted to a predetermined pressure by the pressure regulator 132 and is injected by the fuel injector 134 into each cylinder 150. As a result of the pressure adjustment by the pressure regulator 132, excess fuel is returned to the fuel tank 130 via a return pipe (not shown).

[0028] The cylinder head (not illustrated) of the internal combustion engine 100 contains a cylinder pressure sensor (CPS) 140. The combustion pressure sensor 140 is provided in each cylinder 150 and detects a pressure (combustion pressure) in the cylinder 150.

[0029] The combustion pressure sensor 140 uses a piezoelectric pressure sensor or a calibration-type pressure sensor and can measure the combustion pressure (cylinder pressure) in the cylinder 150 over a wide temperature range.

[0030] An exhaust valve 152 and an exhaust manifold 160, which releases the gas (exhaust gas) after combustion outside the cylinder 150, are fitted to each cylinder 150. A three-way catalytic converter 161 is provided on one exhaust side of the exhaust manifold 160.

[0031] When the exhaust valve 152 is open, the exhaust gas from cylinder 150 is released into the exhaust manifold 160. The exhaust gas flows through the exhaust manifold 160, is cleaned by the three-way catalytic converter 161, and is then released into the atmosphere.

[0032] An upstream air / fuel ratio sensor 162 is provided on the upstream side of the three-way catalyst 161. The upstream air / fuel ratio sensor 162 continuously detects the air / fuel ratio of the exhaust gas exiting each cylinder 150.

[0033] Furthermore, an downstream air / fuel ratio sensor 163 is provided on the downstream side of the three-way catalyst 161. The downstream air / fuel ratio sensor 163 outputs a switch-like detection signal in the vicinity of a theoretical air / fuel ratio. In this embodiment, the downstream air / fuel ratio sensor 163 is, for example, an O2 sensor.

[0034] Furthermore, the spark plug 200 is located in the upper section of each cylinder 150. Due to the discharge (ignition) of the spark plug 200, a spark is ignited in a mixture of air and fuel in the cylinder 150, an explosion occurs in the cylinder 150, and a piston 170 is forced downwards. When the piston 170 is forced downwards, the crankshaft 123 rotates.

[0035] An ignition coil 300, which generates electrical energy (a voltage) that is supplied to the spark plug 200, is connected to the spark plug 200. The discharge is caused by the voltage generated in the ignition coil 300 between a center electrode 210 and an outer electrode 220 of the spark plug 200 (see Fig. 2) generated.

[0036] As in Fig. As illustrated in Figure 2, the center electrode 210 in the spark plug 200 is held in an insulated state by an insulator 230. A predetermined voltage (in this embodiment, for example, 20,000 V to 40,000 V) is applied to this center electrode 210.

[0037] The outer electrode 220 is grounded. When the specified voltage is applied to the center electrode 210, a discharge (ignition) is generated between the center electrode 210 and the outer electrode 220.

[0038] In the spark plug 200, a dielectric breakdown of a gas component is generated due to the condition of a gas present between the center electrode 210 and the outer electrode 220, or due to the cylinder pressure, and the voltage at which the discharge (ignition) is generated is changed. The voltage at which this discharge is generated is called the dielectric breakdown voltage.

[0039] A discharge control (ignition control) of the spark plug 200 is carried out by an ignition control unit 83 of the control device 1, which will be described later.

[0040] With renewed reference to Fig. 1. An output signal from various sensors, such as the throttle valve opening degree sensor 113a, the flow rate sensor 114, the crankshaft angle sensor 121, the accelerator pedal position sensor 126, the water temperature sensor 122, the combustion pressure sensor 140, or the like, as described above, is output to the control device 1. The control device 1 detects an operating state of the internal combustion engine 100 based on the output signals from these various sensors and controls an air quantity sent to the cylinder 150, a fuel injection quantity, an ignition timing setting of the spark plug 200, or the like. [Hardware configuration of the control device]

[0041] Next, the overall hardware configuration of control device 1 will be described.

[0042] As in Fig. As illustrated in Figure 1, the control device 1 includes an analog input unit 10, a digital input unit 20, an analog / digital conversion unit (A / D conversion unit) 30, a read / write memory (RAM) 40 and a microprocessor unit (MPU) 50, a read-only memory (ROM) 60, an input / output port (I / O port) 70 and an output circuit 80.

[0043] The analog output signals from various sensors such as the throttle valve opening degree sensor 113a, the flow rate sensor 114, the accelerator pedal position sensor 126, the upstream air / fuel ratio sensor 162, the downstream air / fuel ratio sensor 163, the combustion pressure sensor 140 and the water temperature sensor 122 are input into the analog input unit 10.

[0044] The A / D conversion unit 30 is connected to the analog input unit 10. The analog output signals from the various sensors, which are input into the analog input unit 10, are subjected to signal processing such as noise reduction, converted into digital signals by the A / D conversion unit 30 and stored in the RAM 40.

[0045] The digital output signal from the crank angle sensor 121 is entered into the digital input unit 20.

[0046] An I / O port 70 is connected to the digital input unit 20, and the digital output signal that is input into the digital input unit 20 is stored in the RAM 40 via the I / O port 70.

[0047] Each output signal stored in RAM 40 is processed arithmetically by the MPU 50.

[0048] The MPU 50 executes a control program (not illustrated) stored in ROM 60 to arithmetically process the output signal stored in RAM 40 according to a control program. The MPU 50 calculates a control value that defines the actuation amount of each actuator (e.g., the throttle valve 113, the pressure regulator 132, the spark plug 200, or the like) that controls the internal combustion engine 100, according to the control program, and temporarily stores the control value in RAM 40.

[0049] The control value, which is stored in RAM 40 and defines the actuation amount of the actuator, is output to the output circuit 80 via the I / O port 70.

[0050] The output circuit 80 has a function of the ignition control unit 83 (see Fig. 3) which controls the voltage applied to spark plug 200. [Functional block of the control device]

[0051] Next, a functional configuration of the control device 1 is described.

[0052] Fig. Figure 3 is a functional block diagram illustrating the functional configuration of the control device 1. For example, each function of the control device 1 is implemented by the output circuit 80 when the MPU 50 executes the control program stored in the ROM 60.

[0053] As in Fig. As illustrated in Figure 3, the output circuit 80 of the control device 1 includes a total control unit 81, a fuel injection control unit 82 and the ignition control unit 83.

[0054] The overall control unit 81 is connected to the accelerator pedal position sensor 126 and the combustion pressure sensor 140 (CPS) and receives a requested torque (acceleration signal S1) from the accelerator pedal position sensor 126 and an output signal S2 from the combustion pressure sensor 140.

[0055] The overall control unit 81 controls the fuel injection control unit 82 and the ignition control unit 83 as a whole on the basis of the requested torque (the acceleration signal S1) from the accelerator pedal position sensor 126 and the output signal S2 from the combustion pressure sensor 140.

[0056] The fuel injection control unit 82 is connected to a cylinder determination unit 84, which determines each cylinder 150 of the internal combustion engine 100, an angle information generation unit 85, which measures a crank angle of the crankshaft 123, and a speed information generation unit 86, which measures an engine speed, and receives cylinder differentiation information S3 from the cylinder determination unit 84, crank angle information S4 from the angle information generation unit 85, and engine speed information S5 from the speed information generation unit 86.

[0057] Furthermore, the fuel injection control unit 82 is connected to an intake quantity measuring unit 87, which measures an intake quantity of air that is drawn into the cylinder 150, a load information generating unit 88, which measures an engine load, and a water temperature measuring unit 89, which measures a temperature of the engine coolant, and receives intake air quantity information S6 from the intake quantity measuring unit 87, engine load information S7 from the load information generating unit 88, and coolant temperature information S8 from the water temperature measuring unit 89.

[0058] The fuel injection control unit 82 calculates an injection quantity of fuel to be injected by the fuel injector 134 and an injection time (fuel injector control information S9) based on the received information and controls the fuel injector 134 based on the calculated fuel injection quantity and injection time.

[0059] The ignition control unit 83 is connected to the cylinder determination unit 84, the angle information generation unit 85, the speed information generation unit 86, the load information generation unit 88, and the water temperature measuring unit 89, in addition to the overall control unit 81, and receives the respective information from these.

[0060] Based on the received information, the ignition control unit 83 calculates an amount of current (excitation angle) to excite a primary coil (not illustrated) of the ignition coil 300, an excitation start time and a time (ignition time) at which the current to excite the primary coil is interrupted.

[0061] The ignition coil 300 contains multiple coils. The embodiment illustrates an example in which the ignition coil 300 contains four coils 300a to 300d. Hereinafter, the coils 300a to 300d that form the ignition coil 300 may be referred to as "ignition coils". However, the number of coils that form the ignition coil 300 is not limited to four, and any number of coils can be combined.

[0062] Based on the calculated excitation angle, excitation start time, and ignition timing, the ignition control unit 83 outputs the ignition signal SA to the primary coil 310 of each of the ignition coils 300a to 300d and performs a discharge control (ignition control) through the spark plug 200. This results in multiple discharges of the spark plug 200.

[0063] At least one function of an ignition control unit 83, to control the ignition of the spark plug 200 using an ignition signal SA, corresponds to the control device for an internal combustion engine of the present invention. [Electrical circuit of the ignition coil]

[0064] Next, an electrical circuit 400a, containing the ignition coil 300a, is described as a representative of the four coils 300a to 300d that make up the ignition coil 300. The other ignition coils 300b to 300d also have the same electrical circuit as the electrical circuit 400a.

[0065] Fig. Figure 4 is a diagram illustrating the electrical circuit 400a, which includes the ignition coil 300a. In the electrical circuit 400a, the ignition coil 300a is configured to include the primary coil 310, wound with a predetermined number of turns, and a secondary coil 320, wound with a greater number of turns than the primary coil 310.

[0066] One end of the primary coil 310 is connected to a DC power supply 330. As a result, a predetermined voltage (e.g., 12 V in this embodiment) is applied to the primary coil 310. A charge quantity detection unit 350 is provided in a connection path between the DC power supply 330 and the primary coil 310. The charge quantity detection unit 350 detects the voltage and current applied to the primary coil 310 and transmits the detected voltage and current to the ignition control unit 83.

[0067] The other end of the primary coil 310 is connected to an ignition device 340 and is grounded via the ignition device 340. A transistor, a field-effect transistor (FET), or the like is used for the ignition device 340.

[0068] A base terminal (B) of the ignition device 340 is connected to the ignition control unit 83. The ignition signal SA, output by the ignition control unit 83, is input to the base terminal (B) of the ignition device 340. When the ignition signal SA is input to the base terminal (B) of the ignition device 340, a collector terminal (C) and an emitter terminal (E) of the ignition device are energized, and a current flows between the collector terminal (C) and the emitter terminal (E). Accordingly, the ignition signal SA is output by the ignition control unit 83 via the ignition device 340 to the primary coil 310 of the ignition coil 300a, and electrical power (electrical energy) is stored in the primary coil 310.

[0069] When the ignition signal SA is stopped by the ignition control unit 83 and the current flowing through the primary coil 310 is interrupted, a high voltage is generated in the secondary coil 320, corresponding to a ratio of the number of turns in the secondary coil to that of the primary coil 310. By applying this high voltage generated in the secondary coil 320 to the spark plug 200 (the center electrode 210), a potential difference is created between the center electrode 210 and the outer electrode 220 of the spark plug 200. If the potential difference generated between the center electrode 210 and the outer electrode 220 is equal to or greater than a dielectric breakdown voltage Vm of the gas (the mixture in the cylinder 150), a gas component is dielectrically broken down, a discharge is generated between the center electrode 210 and the outer electrode 220, and the fuel (the air / fuel mixture) is ignited.

[0070] A discharge quantity detection unit 360 is provided in a connection path between the secondary coil 320 and the spark plug 200. The discharge quantity detection unit 360 detects the discharge voltage and the discharge current and sends these to the ignition control unit 83.

[0071] The ignition control unit 83 controls the excitation of ignition coil 300a using the ignition signal SA by operating the electrical circuit 400a as described above. The excitation of the other ignition coils 300b to 300d is controlled using the ignition signal SA by the same operation of the electrical circuit. As a result, the electrical energy applied to spark plug 200 by ignition coils 300a to 300d is controlled, and the ignition control for multiple discharges of spark plug 200 is carried out.

[0072] In electrical circuit 400a, which is in Fig. As illustrated in Figure 4, either the DC power supply 330 or the charge quantity detection unit 350 or the discharge quantity detection unit 360 can be used jointly by the ignition coils 300a to 300d, or each coil can be provided individually. [Comparison with the conventional method]

[0073] Next, the discharge control of the spark plug 200 according to the embodiment will be described in comparison to the conventional method.

[0074] Fig. Figure 5 is a schematic diagram illustrating an example of a conventional multiple discharge method. The target charge quantities of all ignition coils 300a to 300d, which constitute ignition coil 300, are determined by the engine speed (the ignition cycle) or the charging voltage such that the amount of energy consumed per unit of time is approximately the same.

[0075] In the conventional multiple discharge method, the ignition control unit 83 refers to predefined mapping information and simultaneously outputs the ignition signal SA with a pulse width corresponding to the target charge quantity to all ignition coils 300a to 300d (ignition device 340). Each of the ignition coils 300a to 300d stores electrical energy while receiving the ignition signal SA and simultaneously begins to release the stored electrical energy when the reception of the ignition signal SA ends. The release of electrical energy from the ignition coils 300a to 300d applies a high voltage between the electrodes of the spark plug 200, which is connected to the ignition coils 300a to 300d, and a discharge is generated.

[0076] In Fig. 5(a) Reference numeral 501 indicates a change over time of an interelectrode voltage of the spark plug 200. A section of reference numeral 502, in which the interelectrode voltage 501 is significantly changed, indicates the generation of ions (ignition ions) due to the ignition of the fuel.

[0077] Furthermore, reference 503 specifies a time-dependent change in a voltage that can be supplied to spark plug 200 by ignition coil 300, and reference 504 specifies a time-dependent change in a required voltage necessary to maintain the discharge of spark plug 200. Additionally, reference 505, for comparison with the supplyable voltage 503, specifies a time-dependent change in the supplyable voltage when eight coils are used as the ignition coil 300. However, as described above, ignition coil 300 is actually configured with the four ignition coils 300a to 300d. Accordingly, the supplyable voltage 505 cannot be supplied to spark plug 200.

[0078] As in Fig. As illustrated in Figure 5(a), the required voltage 504 corresponds to the interelectrode voltage 501 during the period from the start of the discharge of the spark plug 200 until the interruption of the discharge. That is, during this period, the required voltage 504 can be determined by the discharge quantity detection unit 360. Fig. 4 are detected. Here, the interelectrode voltage (the secondary voltage output by the secondary coil 320) of the spark plug 200 is generally represented by a negative value. Therefore, in Fig. 5(a) the magnitudes of the stresses 501 to 505 are represented by negative values.

[0079] In the following description, the increase (rise) or decrease (fall) of any voltage in a negative direction is simply referred to as "increase (rise)" or "decrease (fall)".

[0080] As in Fig. As illustrated in Figure 5(a), the supply voltage 503 rises abruptly when electrical energy is released simultaneously from the ignition coils 300a to 300d, and then gradually decreases over time. Meanwhile, the required voltage 504 (the interelectrode voltage 501) gradually increases over time. This is because the length of the discharge path between the electrodes of the spark plug 200 increases over time from the start of the discharge. Generally, a gas flow occurs in the combustion chamber of an engine. Due to the gas flow, the discharge path lengthens over time from the start of the discharge, and thus the required voltage 504 is increased. As a result, the discharge path cannot be sustained, and the discharge is interrupted, when the supply voltage 503 is lower than the required voltage 504. Fig. Figure 5(b) illustrates an example of an extension of the discharge path from the start of the discharge until immediately before (immediately before the re-ignition) the interruption of the discharge. When the discharge is interrupted, the intermediate electrode voltage 501 is abruptly reduced and deviates from the required voltage 504, as shown in Fig. 5(a) is illustrated.

[0081] Here is in Fig. 5(a) The difference between the supply voltage 503 and the required voltage 504 is greatest at the beginning of the discharge and decreases over time. That is, when the difference between the supply voltage 503 and the required voltage 504 is large, as it is immediately after the start of the discharge, an excessive voltage is applied from the ignition coil 300 to the spark plug 200 with respect to the voltage required to maintain the discharge path. Accordingly, an excessive current flows between the electrodes of the spark plug 200. Such excessive voltage and current are consumed as excess energy that is unnecessary for maintaining the discharge path. As a result, for example, in the example from Fig. 5(a) the discharge is interrupted approximately 0.8 ms after the start of the discharge. The difference between the supply voltage 503 and the required voltage 504 (the intermediate electrode voltage 501) from the start of the discharge until the interruption of the discharge, indicated by the hatching in Fig. The excess energy shown in 5(a) is represented above.

[0082] Fig. Figure 6 is a schematic diagram illustrating an example of the multiple discharge method according to the embodiment of the present invention. As in the conventional method described in Fig. As described in section 5, the target charge quantities of all ignition coils 300a to 300d, which form the ignition coil 300, are determined by the engine speed (the ignition cycle) or the charging voltage in such a way that the amount of energy consumption per unit of time is approximately the same.

[0083] In the multiple discharge method according to the embodiment, the ignition control unit 83 refers to predetermined imaging information and outputs the ignition signal SA successively to each ignition coil 300a to 300d (ignition device 340) with a time specification based on the target charge quantity. At this point, the ignition control unit 83 outputs the ignition signal SA with a pulse width that corresponds to the target charge quantity with respect to the first ignition coil 300a, as in the conventional method. However, with respect to each of the second and subsequent ignition coils 300b to 300d, immediately before the supplyable voltage to the ignition coil 300 is lower than the required voltage, electrical energy is supplied to the spark plug 200 from the ignition coils 300b to 300d, and the pulse width of the ignition signal SA is controlled and output such that the spark plug 200 is discharged continuously.Each of the ignition coils 300a to 300d stores electrical energy while receiving the ignition signal SA and sequentially begins to release the stored electrical energy when the reception of the ignition signal SA ends. The release of electrical energy from the ignition coils 300a to 300d applies a high voltage between the electrodes of the spark plug 200, which is connected to the ignition coils 300a to 300d, and generates a discharge.

[0084] In Fig. 6(a) Reference numeral 601 indicates a change over time of the intermediate electrode voltage of the spark plug 200. Reference numeral 603 indicates a change over time of the voltage that can be supplied to the spark plug 200 by the ignition coil 300, and reference numeral 604 indicates a change over time of the required voltage necessary to maintain the discharge of the spark plug 200.

[0085] Furthermore, a reference numeral 605 indicates, for comparison with the supply voltage 603, a change in the supply voltage over time when eight coils are used as the ignition coil 300. However, the ignition coil 300 is, as in the case of Fig. 5(a) is actually configured with the four ignition coils 300a to 300d. Accordingly, the supply voltage 605 cannot be supplied to the spark plug 200. Furthermore, in Fig. 6(a) as in Fig. 5(a) the magnitude of each of the stresses 601 to 605 is represented by a negative value.

[0086] As in Fig. As illustrated in Figure 6(a), the supplyable voltage 603 increases each time electrical energy is successively released from the ignition coils 300a to 300d and gradually decreases over time. Meanwhile, the required voltage 604 (the interelectrode voltage 601) also increases, as shown in Figure 6(a). Fig. 5(a) gradually increases over time. As a result, the discharge path cannot be maintained, and the discharge is interrupted when the supplyable voltage 603 is lower than the required voltage 604 after the fourth release of electrical energy. Fig. Figure 6(b) illustrates an example of extending the discharge path from the start of the discharge until immediately before (immediately before re-ignition) the interruption of the discharge. As in Fig. 5(a) is in Fig. 6(a) the intermediate electrode voltage 601 is abruptly reduced and deviates from the required voltage 604 when the discharge is interrupted.

[0087] A difference between the supplyable voltage 603 and the required voltage 604 (the intermediate electrode voltage 601) from the start of the discharge until the interruption of the discharge, indicated by the hatching in Fig. The excess energy specified in 6(a) represents the energy required to maintain the discharge path. This excess energy is less than the excess energy in the conventional method described in Fig. 5(a) is illustrated. That is, in the multiple discharge method according to the embodiment, the excess energy with respect to maintaining the discharge path can be dissipated by distributing and releasing the electrical energy from the ignition coils 300a to 300d compared with that of the conventional multiple discharge method, which is illustrated in Fig. As described in 5(a), the result will be reduced. For example, in the example from Fig. 6(a) the discharge is interrupted approximately 1.2 ms after the start of the discharge, and the time until the discharge is interrupted can be extended compared to that of the conventional method. Furthermore, as in Fig. As illustrated in Figure 6(b), the discharge path immediately before the interruption of the discharge is lengthened compared to that of the conventional method. Therefore, it is understood that the multiple discharge method according to the embodiment can improve the ignition capability compared to the conventional method. [Spark plug control method]

[0088] Next, an example of a control procedure for the spark plug 200 by the ignition control unit 83 is described. Fig. Figure 7 is an example of a flow chart illustrating a method for controlling the spark plug 200 by the ignition control unit 83 according to the embodiment.

[0089] As in Fig. As illustrated in Figure 7, the ignition control unit 83 determines in step S101 whether a discharge interruption time was detected in the preceding process. If the discharge interruption time was detected during the preceding process by executing step S107 described below (step S101: Yes), the process proceeds to step S102, and if the discharge interruption time was not detected in the preceding process (step S101: No), the process proceeds to step S103.

[0090] In step S102, the ignition control unit 83 corrects a threshold value for controlling the excitation of the respective ignition coils from ignition coils 300a to 300d, from which the electrical energy is released in the second repetition and in the following repetitions, that is, ignition coils 300b to 300d. This threshold value is determined in a determination process from step S308. Fig. 9, which is described later, is used, and a time specification for the supply of electrical energy from the ignition coils 300b to 300d to the spark plug 200 is controlled by the threshold value.

[0091] In step S103, the ignition control unit 83 sets the target charge quantity for each of the ignition coils 300a to 300d based on the engine speed, represented by the engine speed information S5 from the speed information generation unit 86, or the charging voltage of each of the ignition coils 300a to 300d, detected by the charge quantity detection unit 350. For example, it is possible to set the target charge quantity according to the engine speed or the charging voltage by referring to the mapping information stored in ROM 60 in the control device 1. In the excitation control process, which is carried out in step S105, described below, an excitation time of the primary coil 310 in each of the ignition coils 300a to 300d is adjusted based on the charge quantity set here.

[0092] In step S104, the excitation control unit 83 sets a charging start time for each of the ignition coils 300a to 300d based on the target charge quantity set in step S103. For example, a discharge interval for each of the ignition coils 300a to 300d is stored in the previous process, and the charging start time is set such that the time difference until the target charge quantity has been applied to each of the ignition coils 300a to 300d is equal to the discharge interval. Alternatively, the charging start times for all ignition coils 300a to 300d can be the same. Furthermore, it is possible to set the charging start time for each of the ignition coils 300a to 300d using any method.

[0093] In step S105, the ignition control unit 83 performs the excitation control process for each of the ignition coils 300a to 300d. Here, the excitation control process for each of the ignition coils 300a to 300d is carried out by controlling the ignition signal SA output to each of the ignition coils 300a to 300d. The details of the excitation control process performed in step S105 will be described later with reference to Fig. 8 and Fig. 9 described.

[0094] In step S106, the ignition control unit 83 determines, based on the voltage (inter-electrode voltage) or current of spark plug 200, detected by the discharge quantity detection unit 360, whether the discharge of spark plug 200 is interrupted or not. If the discharge interruption is detected (step S106: Yes), the process continues to step S107, and if the discharge interruption is not detected (step S106: No), the process continues to step S108.

[0095] In step S107, the ignition control unit 83 detects a discharge interruption time, which specifies the time at which the discharge interruption occurs in the spark plug 200. For example, the elapsed time from the start of the discharge until it is determined in step S106 that the discharge is interrupted, is when the discharge interruption time is detected. When the discharge interruption time is detected in step S107, the information is stored in RAM 40, and the process proceeds to step S108.

[0096] In step S108, the ignition control unit 83 determines whether electrical energy has been supplied to spark plug 200 by all ignition coils 300a to 300d or not. In the excitation control process from step S105, the excitation of all ignition coils 300a to 300d has been completed, and if electrical energy can no longer be supplied by ignition coil 300 (step S108: Yes), the process sequence ends. Fig. 7. However, if there is at least one ignition coil from ignition coils 300a to 300d to which electrical energy is not supplied (step S108: No), the process returns to step S105 to continue the excitation control process.

[0097] Next, details of the excitation control process, which is executed in step S105, will be described. Fig. Figure 8 is an example of a flowchart to explain the excitation control process, which is carried out for the ignition coil from ignition coils 300a to 300d, whose electrical energy is first released, that is, ignition coil 300a. Fig. Figure 9 is an example of a flowchart illustrating an excitation control process that is carried out for each of the ignition coils from ignition coils 300a to 300d, whose electrical energy is released in the second repetition and in the following repetitions, that is, for each of the ignition coils 300b to 300d.

[0098] First, the schedule will be drawn from Fig. 8 described. As in Fig. As illustrated in 8, the ignition control unit 83 determines in step S201 based on the charging process start time specification, which is derived in step S104 from Fig. Step 7 determines whether charging of ignition coil 300a should be started. Step S201 is repeated until it is determined that charging should be started (Step S201: No), and if it is determined that charging should be started (Step S201: Yes), the process continues to step S202.

[0099] In step S202, the ignition control unit 83 activates the pulse of the ignition control signal SA to start charging the ignition coil 300a. According to the output of the ignition signal SA, electrical energy is stored in the primary coil 310 of the ignition coil 300a.

[0100] In step S203, the ignition control unit 83 determines whether the charge quantity of the ignition coil 300a reaches the target charge quantity set in step S103. For example, based on a detection result from the charge quantity detection unit 350, a current charge quantity of the ignition coil 300a is estimated, and the determination in step S203 can be performed depending on whether the estimated value reaches the target charge quantity. Alternatively, the pulse width of the ignition signal SA is set based on the target charge quantity set in step S103, and the determination in step S203 is performed depending on whether a certain time elapsed since the ignition signal SA was started in step S202 reaches this pulse width.As a result, step S203 is repeated until it is determined that the charge quantity of ignition coil 300a reaches the target charge quantity (step S203: No), and if it is determined that the charge quantity reaches the target charge quantity (step S203: Yes), the process continues to step S204.

[0101] In step S204, the ignition control unit 83 switches off the pulse of the ignition control signal SA and stops charging the ignition coil 300a. In response to the cessation of the output of the ignition signal SA, the electrical energy stored in the ignition coil 300a is supplied by the secondary coil 320 to the spark plug 200. When the output of the ignition signal SA is stopped in step S204, the excitation control process for the ignition coil 300a, which is shown in the flowchart below, ends. Fig. Figure 8 illustrates this.

[0102] Next, the schedule will be drawn from Fig. 9 described. In the following description, an ignition coil from ignition coils 300b to 300c, which is a control target in the flow diagram, is referred to as a "control target coil".

[0103] As in Fig. As illustrated in 9, the ignition control unit 83 determines in step S301 based on the charging process start time specification, which is derived in step S104 from Fig. Step 7 determines whether or not charging of the control target coil should be started. Step S301 is repeated until it is determined that charging should be started (Step S301: No), and if it is determined that charging should be started (Step S301: Yes), the process continues to step S302.

[0104] In step S302, the ignition control unit 83 activates the pulse of the ignition control signal SA to start charging the control target coil. Based on the output of this ignition signal SA, electrical energy is stored in the primary coil 310 of the control target coil.

[0105] In step S303, the ignition control unit 83 uses the charge quantity detection unit 350 to detect the amount of electrical energy currently stored in the control target coil. Here, the charge quantity of the control target coil can be detected by determining an integrated value of the voltage and current of the primary coil 310 in the control target coil, as detected by the charge quantity detection unit.

[0106] In step S304, the ignition control unit 83 determines whether the ignition, due to the discharge of the spark plug 200, exceeds a predetermined ignition timing range using the electrical energy of the control target coil. For example, it determines whether the charge of the control target coil, detected in step S303, is greater than or equal to a predetermined value. If the charge is greater than or equal to the predetermined value, the control target coil is magnetically saturated and cannot be charged further. Accordingly, it is determined that the ignition timing range has elapsed (step S304: Yes), and the process proceeds to step S310. The predetermined charge value used for this determination is greater than the target charge of the control target coil, which was determined in step S103. Fig. 7 has been set. However, if the charge quantity of the control target coil is less than the specified value, it is determined that the ignition time setpoint range has not yet expired (step S304: No), and the process continues to step S305.

[0107] In step S304, a method other than the one described above can be used to determine whether the ignition timing target range has elapsed or not. For example, based on the time elapsed since the start of the first discharge, using the electrical energy of the ignition coil 300a, the engine speed, the opening degree of the throttle valve 113, the fuel injection quantity, or the like, it can be determined whether the ignition timing target range has been exceeded or not.

[0108] In step S305, the ignition control unit 83 estimates the supplyable voltage of the electrical energy currently being supplied to the spark plug 200. At this point, the ignition control unit 83 determines, for example, the amount of electrical energy released by the discharge of the spark plug 200 by determining the integrated value of the discharge voltage and discharge current detected by the discharge quantity detection unit 360. Subsequently, by subtracting the amount of electrical energy due to this discharge from the amount of electrical energy supplied to the spark plug 200 by all ignition coils 300, the amount of electrical energy currently available in the ignition coil 300 is estimated, and the supplyable voltage can be estimated based on this estimated value.The amount of electrical energy supplied to the spark plug 200 by all ignition coils 300 is obtained as a sum of the charge amounts that have been finally stored in the respective ignition coils by the ignition coils 300a to 300d, which form the ignition coil 300, that have released the electrical energy.

[0109] For example, in step S204, from Fig. 8. Then, when the pulse of the ignition signal SA has been switched from ON to OFF with respect to the ignition coil 300a and the ignition coil 300b is being charged, the amount of electrical energy supplied to the spark plug 200 is determined by determining the amount of charge that has ultimately been stored in the ignition coil 300a. In particular, in step S204, from Fig. 8 the charge quantity immediately before the pulse of the ignition signal SA is switched from ON to OFF with respect to the ignition coil 300a, that is, the amount of electrical energy that has been supplied to the spark plug 200, from the target charge quantity of the ignition coil 300a, which in step S103 from Fig. The voltage that has been set to 7 is determined. Subsequently, a current supplyable voltage is estimated by estimating the voltage that can be supplied to the spark plug 200 by the ignition coil 300a using the amount of electrical energy.

[0110] Furthermore, for example in step S309, which is described later, when the pulse of the ignition signal SA has been switched from ON to OFF with respect to ignition coil 300b and ignition coil 300c is being charged, the amount of electrical energy supplied to spark plug 200 is determined by summing the amounts of charge that have ultimately been stored in ignition coils 300a and 300b. At this point, the amount of charge that has ultimately been stored in ignition coil 300b is determined from the amount of charge that was ultimately detected in step S303. Subsequently, using this amount of electrical energy, the current supplyable voltage is estimated by estimating the voltage that can be supplied to spark plug 200 by ignition coils 300a and 300b.

[0111] Similarly, in step S309, which is described later, when the pulse of the ignition signal SA has been switched from ON to OFF at ignition coil 300c and ignition coil 300d is being charged, the amount of electrical energy supplied to spark plug 200 is determined by summing the amounts of charge that have ultimately been stored in ignition coils 300a, 300b, and 300c. Then, using this amount of electrical energy, the current supplyable voltage is estimated by estimating the voltage that can be supplied to spark plug 200 by ignition coil 300a, ignition coil 300b, and ignition coil 300c.

[0112] If the ignition coil 300 is configured with four or more coils, the same process as above can be repeated for the number of coils. In step S305, the voltage that can be supplied to the spark plug 200 by the ignition coil 300 is thus estimated.

[0113] In step S306, the ignition control unit 83 detects the required voltage necessary to maintain the discharge of the spark plug 200. At this point, the ignition control unit 83 can, as in Fig. As described in 6(a), when the discharge of the spark plug 200 continues, the required voltage is detected by the discharge quantity detection unit 360, which detects the interelectrode voltage of the spark plug 200. The required voltage detected here is modified according to the state of the internal combustion engine 100. In particular, the required voltage is modified according to the rotational speed of the internal combustion engine 100, represented by the engine speed information S5 from the rotational speed information generation unit 86, the degree of opening of the throttle valve 113, detected by the throttle valve opening sensor 113a, the fuel injection quantity from the fuel injector 134, calculated by the fuel injection control unit 82, or the like.Furthermore, the required voltage is also changed depending on the opening degree of the wobble motion generation valve if a wobble motion generation valve is fitted to the internal combustion engine 100.

[0114] In step S307, the ignition control unit 83 calculates a difference d between the supplyable voltage, which was estimated in step S305, and the required voltage, which was detected in step S306.

[0115] In step S308, the ignition control unit 83 determines whether the difference d between the supply voltage calculated in step S307 and the required voltage is less than or equal to a predefined threshold value. If the difference d is greater than the threshold value (step S308: No), the process returns to step S303, and the excitation control of the target control coil continues.

[0116] However, if the difference d is less than or equal to the threshold (step S308: Yes), the process continues to step S309.

[0117] In step S309, the ignition control unit 83 switches off the pulse of the ignition control signal SA for an ignition coil that has the highest priority among the control target coils that have not yet released the electrical energy, thus ending the charging of the ignition coil. When the output of the ignition signal SA is stopped, the electrical energy stored in the ignition coils 300b to 300d is supplied sequentially to the spark plug 200 from the secondary coil 320.

[0118] In particular, in step S309, after the electrical energy of the ignition coil 300a has been supplied to the spark plug 200, the ignition control unit 83 then, if the difference d between the voltage that can be supplied to the spark plug 200 by the ignition coil 300a and the required voltage is less than or equal to the specified threshold value, controls the excitation of the ignition coil 300b such that the electrical energy of the ignition coil 300b is supplied to the spark plug 200. Furthermore, in step S309, after the electrical energy of the ignition coil 300b has been supplied to the spark plug 200, the ignition control unit 83 then, if the difference d between the voltage that can be supplied to the spark plug 200 by the ignition coil 300a and the ignition coil 300b, and the required voltage is less than or equal to the specified threshold value, controls the excitation of the ignition coil 300c, such that the electrical energy of the ignition coil 300c is supplied to the spark plug 200.Furthermore, in step S309, after the electrical energy from the ignition coil 300c has been supplied to the spark plug 200, the ignition control unit 83 then, if the difference d between the voltage that can be supplied to the spark plug 200 by the ignition coil 300a, the ignition coil 300b, and the ignition coil 300c, and the required voltage, is less than or equal to the predetermined threshold, controls the excitation of the ignition coil 300d, such that the electrical energy from the ignition coil 300d is supplied to the spark plug 200. Here, the same process as above can be repeated for the number of coils if the ignition coil 300 is configured with four or more coils.

[0119] Before the electrical energy is supplied to spark plug 200 from the control target coil in step S309, the required voltage detected in step S306 is lower than that before the discharge interruption, when in step S107 from Fig. 7 the discharge interruption time is detected and the discharge of the spark plug 200 is then restarted using the ignition coil 300a, as above with reference to Fig. 5(a) is described. Therefore, in this case, the period until it is detected that the difference d between the supplyable voltage and the required voltage is less than or equal to the threshold is extended in step S308, and as a result, the time at which the electrical energy from the control target coil is supplied to spark plug 200 is delayed. Accordingly, it is possible to supply the electrical energy from ignition coils 300a to 300d to spark plug 200 when the discharge is interrupted after waiting until the discharge path is long again after the discharge has restarted. Therefore, it is possible to prevent an excessive supply of electrical energy after the discharge has restarted.

[0120] Furthermore, the threshold used in the determination from step S308 is corrected in step S102 if the discharge is interrupted when the schedule from Fig. 7 is executed consecutively. At this point, the electrical energy of the ignition coils 300b to 300d is supplied to the spark plug 200 by correcting the threshold value so that it is greater than before, when the spark plug 200 is successively discharged using the electrical energy of the ignition coil 300a before the discharge interruption time is detected in step S107, in order to continue the discharge of the spark plug 200, and the excitation of the ignition coils 300b to 300d can be controlled such that the discharge is not interrupted. In step S102, the threshold value can be adjusted. B. on the basis of the discharge interruption time detected in step S107, or the magnitude of the required voltage detected by the discharge quantity detection unit 360 in step S306 immediately before the discharge is interrupted.

[0121] As the process progresses from step S304 to step S310, the ignition control unit 83 stops charging the target control coil in step S310. For example, the electrical energy stored in the target control coil is discharged to stop charging by supplying electrical energy from the target control coil to spark plug 200 at a time when there is no effect on a combustion cycle, thus discharging spark plug 200. Alternatively, by slowly lowering the voltage of the ignition signal SA to be output to the target control coil and gradually changing the ignition signal SA from ON to OFF, it is possible to release the electrical energy stored in the target control coil to stop charging the target control coil without discharging spark plug 200. Accordingly, in step S107, Fig. 7 the discharge interruption time is detected, and if the ignition time target range of the control target coil is subsequently exceeded by restarting the discharge of the spark plug 200 using the ignition coil 300a, it is possible to prevent wasteful discharge of the spark plug 200 by preventing the electrical energy of the control target coil from being supplied to the spark plug 200.

[0122] After executing the process from step S309 or step S310, the ignition control unit 83 terminates the excitation control process, which is shown in the flowchart from Fig. Figure 9 illustrates the ignition coil.

[0123] According to the embodiment described above, the following operational effects are offered. (1) The control device 1 for an internal combustion engine includes the ignition control unit 83, which controls the excitation of the ignition coil 300a and the ignition coil 300b, which each supply electrical energy to the spark plug 200, which discharges into the cylinder 150 of the internal combustion engine 100 to ignite the fuel; and the discharge quantity detection unit 360, which detects the interelectrode voltage of the spark plug 200.After the ignition control unit 83 has discharged the spark plug 200 using the electrical energy of the ignition coil 300a (step S204), the ignition control unit estimates the voltage that can be supplied to the spark plug 200 by the ignition coil 300a (step S305) and controls the excitation of the ignition coil 300b such that the electrical energy of the ignition coil 300b is supplied to the spark plug 200 (step S309) if the difference d between the estimated supplyable voltage and the voltage required to maintain the discharge of the spark plug 200, based on the voltage detected by the discharge quantity detection unit 360, is less than or equal to the predetermined threshold (step S308: Yes). Accordingly, it is possible to improve the ignitability of the fuel by the spark plug 200 while preventing an increase in the number of ignition coils. (2) The discharge quantity detection unit 360 further detects the current flowing between the electrodes of the spark plug 200. After the ignition control unit 83 has discharged the spark plug 200 using the electrical energy of the ignition coil 300a, the ignition control unit 83 detects a discharge interruption time based on the voltage or current detected by the discharge quantity detection unit 306 (steps S106 and S107). Accordingly, it is possible to adequately detect the discharge interruption time when the discharge of the spark plug 200 is interrupted.

[0124] (3) When the ignition control unit 83 discharges the spark plug 200 using the electrical energy of the ignition coil 300a after detecting the discharge interruption time, the ignition control unit 83 controls the excitation of the ignition coil 300b such that the spark plug 200 receives the electrical energy of the ignition coil 300b before the discharge interruption time. In particular, the ignition control unit 83 corrects the threshold value based on the discharge interruption time and / or the voltage detected by the discharge quantity detection unit 360 (step S102) when the ignition control unit 83 detects the discharge interruption time (step S101: Yes). Accordingly, it is possible to prevent the occurrence of the discharge interruption of the next repetition when the discharge of the spark plug 200 is interrupted, such that the discharge continues and the ignition capability is improved.

[0125] (4) When the ignition control unit 83 detects the discharge interruption time, the ignition control unit 83 delays a time at which the electrical energy from the ignition coil 300b is supplied to the spark plug 200 (steps S306 to S309) or controls the excitation of the ignition coil 300b such that the electrical energy from the ignition coil 300b is not supplied to the spark plug 200 (step S310). Accordingly, it is possible to prevent an excessive supply of electrical energy and a wasteful discharge when the discharge of the spark plug 200 is restarted after the discharge interruption.

[0126] (5) The required voltage is changed according to the rotational speed of the internal combustion engine 100 and / or the opening degree of the throttle valve 113 attached to the internal combustion engine 100 and / or the opening degree of a wobble motion generating valve attached to the internal combustion engine 100 and / or the amount of fuel injected from the fuel injector 134 attached to the internal combustion engine 100. Accordingly, the supply time of the electrical energy from the ignition coil 300b to the spark plug 200 can be determined using the appropriate required voltage according to the state of the air / fuel mixture in the internal combustion engine 100.

[0127] (6) Ignition coil 300a and ignition coil 300b each have a primary coil 310, which is excited by the ignition control unit 83 to store electrical energy, and a secondary coil 320, which supplies the spark plug 200 with the electrical energy stored in the primary coil 310. The ignition control unit 83 sets the target charge quantities of ignition coil 300a and ignition coil 300b (step S103) and adjusts the excitation time of the primary coil 310 based on the set target charge quantities (step S105). Accordingly, it is possible to adjust the excitation time of each ignition coil appropriately. (7) The spark plug 200 is also connected to the ignition coil 300c.

[0128] After the ignition control unit 83 has supplied the electrical energy of the ignition coil 300b to the spark plug 200, the ignition control unit 83 estimates a voltage that can be supplied to the spark plug 200 from the ignition coil 300a and the ignition coil 300b (step S305) and controls the excitation of the ignition coil 300c such that the electrical energy of the ignition coil 300c is supplied to the spark plug 200 (step S309) if the difference d between the estimated supplyable voltage and the required voltage is less than or equal to the threshold value (step S308: Yes).

[0129] Accordingly, it is possible to continue the unloading. (8) The spark plug 200 is also connected to the ignition coil 300d.

[0130] After the ignition control unit 83 has supplied the spark plug 200 with the electrical energy from the ignition coil 300c, the ignition control unit 83 estimates the voltage that can be supplied to the spark plug 200 by the ignition coil 300a, the ignition coil 300b, and the ignition coil 300c (step S305) and controls the excitation of the ignition coil 300d such that the electrical energy from the ignition coil 300d is supplied to the spark plug 200 (step S309) if the difference d between the estimated supplyable voltage and the required voltage is less than or equal to the threshold value (step S308: Yes). Accordingly, it is possible to continue the discharge.

[0131] In the embodiment described above, any functional configuration of the control device 1 that is in Fig.The functionality described in section 3 can be implemented by software executed by the MPU 50 as described above, or by hardware such as a user-programmable gate array (FPGA). Furthermore, these can be combined and used in combination.

[0132] The embodiments and various modification examples described above are merely examples, and the present invention is not limited to these unless the properties of the invention are impaired. Furthermore, the present invention is not limited to these aspects, even though various embodiments and modification examples are described above. Other forms considered within the scope of a technical idea of ​​the present invention are also included within the scope of the present invention. List of reference symbols 1 Control device 10 Analog Input Unit 20 digital input units 30 A / D converters 40 RAM 50 MPU 60 ROM 70 I / O ports 80 Output circuit 81 Total control unit 82 Fuel injection control unit 83 Ignition control unit 84 cylinder determination unit 85 Angle Information Generation Unit 86 Speed ​​Information Generation Unit 87 Inlet quantity measuring unit 88 Load Information Generation Unit 89 Water temperature measuring unit 100 internal combustion engine 110 Air purification unit 111 Inlet pipe 112 Inlet distributor pipe 113 Throttle valve 113a Throttle valve opening degree sensor 114 Flow rate sensor 115 Intake air temperature sensor 120 ring gear 121 Crank angle sensor 122 Water temperature sensor 123 Crankshaft 125 Accelerator pedal 126 Accelerator pedal position sensor 130 fuel tanks 131 Fuel pump 132 pressure regulators 133 Fuel pipe 134 Fuel injector 140 Combustion pressure sensor 150 cylinders 151 Inlet valve 152 Exhaust valve 160 Outlet distributor pipe 161 Three-way catalyst 162 Upstream air / fuel ratio sensor 163 Downstream air / fuel ratio sensor 170 pistons 200 spark plug 210 Center electrode 220 external electrode 230 insulator 300, 300a-300d Ignition coil 310 Primary coil 320 Secondary coil 330 DC power supply 340 Ignition device 350 charge quantity detection unit 360° discharge quantity detection unit 400a electrical circuit

Claims

[1] Control device (1) for an internal combustion engine (100) comprising the following: an ignition control unit (83) that controls the excitation of a first ignition coil (300a) and a second ignition coil (300b), each of which provides electrical energy to a spark plug (200) that discharges into a cylinder (150) of an internal combustion engine (100) to ignite a fuel; and a discharge quantity detection unit (360) that detects a voltage between the electrodes of the spark plug (200), wherein the ignition control unit (83), after the ignition control unit (83) has discharged the spark plug (200) using the electrical energy of the first ignition coil (300a), estimates a voltage that can be supplied to the spark plug (200) from the first ignition coil (300a), and controls the excitation of the second ignition coil (300b) such that the electrical energy of the second ignition coil (300b) is supplied to the spark plug (200) when a difference between the estimated supplyable voltage and a voltage required to maintain the discharge of the spark plug (200) based on the voltage detected by the discharge quantity detection unit (360) is less than or equal to a predetermined threshold. [2] Control device (1) for an internal combustion engine (100) according to claim 1, wherein the discharge quantity detection unit (360) further detects a current flowing between the electrodes of the spark plug (200), The ignition control unit (83), after the ignition control unit (83) has discharged the spark plug (200) using the electrical energy of the first ignition coil (300a), detects a discharge interruption time based on the voltage or current detected by the discharge quantity detection unit (360) when the discharge of the spark plug (200) is interrupted. [3] Control device (1) for an internal combustion engine (100) according to claim 2, wherein when the ignition control unit (83) discharges the spark plug (200) using the electrical energy of the first ignition coil (300a) after detecting the discharge interruption time, the ignition control unit (83) controls the excitation of the second ignition coil (300b) such that the electrical energy of the second ignition coil (300b) is supplied to the spark plug (200) before the discharge interruption time. [4] Control device (1) for an internal combustion engine (100) according to claim 3, wherein when the ignition control unit (83) detects the discharge interruption time, the ignition control unit (83) corrects the threshold value on the basis of the discharge interruption time and / or the voltage detected by the discharge quantity detection unit (360). [5] Control device (1) for an internal combustion engine (100) according to claim 2, wherein, when the ignition control unit (83) detects the discharge interruption time, the ignition control unit (83) delays a time specification at which the electrical energy of the second ignition coil (300b) is supplied to the spark plug (200) or controls the excitation of the second ignition coil (300b) such that the electrical energy of the second ignition coil (300b) is not supplied to the spark plug (200). [6] Control device (1) for an internal combustion engine (100) according to claim 1, wherein the required voltage is changed according to a rotational speed of the internal combustion engine (100) and / or an opening degree of a throttle valve (113) attached to the internal combustion engine (100) and / or an opening degree of a wobble motion generating valve attached to the internal combustion engine (100) and / or an injection quantity of fuel from a fuel injection valve (134) attached to the internal combustion engine (100). [7] Control device (1) for an internal combustion engine (100) according to claim 1, wherein the first ignition coil (300a) and the second ignition coil (300b) each have a primary coil (310) which is excited by the ignition control unit (83) to store the electrical energy, and a secondary coil (320) which supplies the electrical energy stored in the primary coil (310) to the spark plug (200), and the ignition control unit (83) sets the target charge quantities of the first ignition coil (300a) and the second ignition coil (300b) and adjusts an excitation time of the primary coil (310) on the basis of the set target charge quantities. [8] Control device (1) for an internal combustion engine (100) according to claim 1, wherein the spark plug (200) is further connected to a third ignition coil (300c) and the ignition control unit (83), after the ignition control unit (83) has supplied the spark plug (200) with the electrical energy of the second ignition coil (300b), estimates a voltage that can be supplied to the spark plug (200) from the first ignition coil (300a) and the second ignition coil (300b), and controls the excitation of the third ignition coil (300c) such that electrical energy from the third ignition coil (300c) is supplied to the spark plug (200) when a difference between the estimated supplyable voltage and the required voltage is less than or equal to the threshold value. [9] Control device (1) for an internal combustion engine (100) according to claim 8, wherein the spark plug (200) is further connected to a fourth ignition coil (300d) and the ignition control unit (83), after the ignition control unit (83) has supplied the spark plug (200) with the electrical energy of the third ignition coil (300c), estimates a voltage that can be supplied to the spark plug (200) from the first ignition coil (300a), the second ignition coil (300b) and the third ignition coil (300c), and controls the excitation of the fourth ignition coil (300d) such that electrical energy from the fourth ignition coil (300d) is supplied to the spark plug (200) when a difference between the estimated supplyable voltage and the required voltage is less than or equal to the threshold value.

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