CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

Abstract

Control device for an internal combustion engine, comprising: an ignition control unit, which controls the excitation of an ignition coil that supplies electrical energy to a spark plug, which performs a discharge in a cylinder of the internal combustion engine and ignites fuel, wherein the ignition control unit specifies a first quantity of electrical energy to generate a discharge between the electrodes of the spark plug and a second quantity of electrical energy to maintain the discharge, After the ignition coil begins to supply electrical energy to the spark plug, the ignition control unit calculates a total amount of electrical energy supplied, and when the calculated total amount becomes greater than or equal to the initial amount of electrical energy, the ignition control unit controls the excitation of the ignition coil so that the ignition coil is charged, and After the ignition coil is charged, the ignition control unit controls the excitation of the ignition coil so that electrical energy greater than or equal to the second amount of electrical energy is delivered from the ignition coil to the spark plug.

Description

Technical field

[0001] The present invention relates to a control device for an internal combustion engine. Current state of the art

[0002] In recent years, to improve the fuel efficiency of vehicles, a control device for an internal combustion engine has been developed, which includes a technology for operating with an air-fuel mixture that is leaner than a theoretical air-fuel ratio, a technology for capturing part of the exhaust gases after combustion and re-intakering them, or the like.

[0003] With this type of control device for an internal combustion engine, the amount of fuel or air in a combustion chamber deviates from a theoretical value, and therefore a spark plug tends to cause a misfire of fuel.

[0004] PTL 1 discloses an ignition control device comprising a spark plug arranged in an internal combustion engine, an ignition device that generates a discharge spark from the spark plug at an ignition time, and an ignition control means for carrying out multiple discharges by repeating the discharge by the ignition device a multitude of times during a combustion cycle of the internal combustion engine, wherein the ignition control means changes the timing of each discharge according to the transition of a pressure in a combustion chamber of the internal combustion engine at the time of the multiple discharge.

[0005] PTL 2 shows an ignition system and a method for operating an ignition system for an internal combustion engine, comprising a primary voltage generator and a boost converter for generating an ignition spark.

[0006] PTL 3 shows a discharge stop device for stopping a spark discharge during discharge, which includes a spark plug, an ignition coil, a power source device, a first switch and a control.

[0007] PTL 4 shows a device for controlling a multiple-spark operation of an internal combustion engine, in which an ignition transformer can be switched off or on again to deliver or interrupt an ignition spark energy based on at least one current threshold. List of quotations Patent literature PTL 1: JP 2001-153016 A PTL 2: DE 10 2014 216 013 A1 PTL 3: DE 10 2017 207 592 A1 PTL 4: DE 10 2007 051 249 A1 Summary of the invention; Technical task

[0008] To improve the ignition quality of the fuel by the spark plug, it is preferable to implement ignition control to maintain the discharge spark for as long as possible after the spark plug generates it. Since the ignition control device disclosed in PTL 1 does not take these points into account, there is the possibility of further improvements to effectively enhance the ignition quality of the fuel by the spark plug.

[0009] Therefore, the present invention was developed with a focus on the problems described above, and one object of the present invention is to effectively improve the ignitability of fuel by a spark plug. Technical solution

[0010] The claimed subject matter is defined by the accompanying claims. In the following, parts of the description and the drawings relating to earlier embodiments, which do not necessarily include all features for implementing embodiments of the claimed subject matter, shall be understood as not representing embodiments of the claimed subject matter, but rather as examples useful for understanding the embodiments of the claimed subject matter. According to one aspect of the present invention, a control device for an internal combustion engine comprises an ignition control unit which controls the excitation of an ignition coil, which supplies electrical energy to a spark plug, which discharges in a cylinder of the internal combustion engine and ignites fuel.wherein: the ignition control unit specifies a first quantity of electrical energy to generate a discharge between the electrodes of the spark plug and a second quantity of electrical energy to sustain the discharge; after the ignition coil begins to supply electrical energy to the spark plug, the ignition control unit calculates a total quantity of electrical energy supplied, and when the calculated total quantity becomes greater than or equal to the first quantity of electrical energy, the ignition control unit controls the excitation of the ignition coil so that the ignition coil is charged; and, after the ignition coil is charged, the ignition control unit controls the excitation of the ignition coil so that electrical energy greater than or equal to the second quantity of electrical energy is supplied from the ignition coil to the spark plug.

[0011] According to a further aspect of the present invention, a control device for an internal combustion engine comprises an ignition control unit which controls the excitation of an ignition coil which supplies electrical energy to a spark plug which performs a discharge in a cylinder of the internal combustion engine and ignites fuel, wherein the ignition control unit specifies a first quantity of electrical energy for generating a discharge between electrodes of the spark plug and a second quantity of electrical energy for maintaining the discharge, and before the ignition coil begins to supply electrical energy to the spark plug, the ignition control unit controls the excitation of the ignition coil such that a quantity of electrical energy accumulated in the ignition coil is greater than or equal to a total value of the first quantity of electrical energy and the second quantity of electrical energy. Advantageous effects of the invention

[0012] According to the present invention, the ignitability of fuel can be effectively improved by a spark plug. Brief description of the drawings [ Fig. 1] Fig. Figure 1 shows a diagram to illustrate a main configuration of an internal combustion engine and a control device for an internal combustion engine according to one embodiment. [ Fig. 2] Fig. Figure 2 shows a partially enlarged view to explain a spark plug. [ Fig. 3] Fig. Figure 3 shows a function block diagram to explain a functional configuration of a control device. [ Fig. 4] Fig. Figure 4 shows a diagram to explain an electrical circuit comprising an ignition coil. [ Fig. 5] Fig. Figure 5 shows a schematic diagram to illustrate an example of a multiple unloading method according to one embodiment. [ Fig. 6] Fig. Figure 6 shows an example of a flow diagram to explain a method for controlling a spark plug by an ignition control unit according to one embodiment. Description of embodiments

[0013] The following describes a control device for an internal combustion engine according to an embodiment of the present invention.

[0014] Below is a description of a control device 1, which is an aspect of the control device for the internal combustion engine according to the embodiment.

[0015] In this embodiment, a case is described in which the device 1 controls the discharge (ignition) of a spark plug 200 arranged in each cylinder 150 of a four-cylinder internal combustion engine 100.

[0016] In one embodiment, a combination of a partial or complete configuration of the internal combustion engine 100 and a partial or complete configuration of the control device 1 refers to the control device 1 for the internal combustion engine 100. [Internal combustion engine]

[0017] Fig. Figure 1 shows a diagram to explain a main configuration of an internal combustion engine 100 and an ignition device for an internal combustion engine.

[0018] Fig. Figure 2 shows a partially enlarged view to explain electrodes 210 and 220 of a spark plug 200.

[0019] In the internal combustion engine 100, the air drawn in from the outside flows through an air filter 110, an intake pipe 111, and an intake manifold 112, and flows into each cylinder 150 when an intake valve 151 is open. The amount of air flowing into each cylinder 150 is regulated by a throttle valve 113, and the amount of air regulated by the throttle valve 113 is measured by a flow sensor 114.

[0020] The throttle valve 113 is equipped with a throttle opening degree sensor 113a, which detects the throttle opening degree. The throttle opening degree information detected by the throttle opening degree sensor 113a is output to a control device (electronic control unit) 1.

[0021] An electronic throttle valve driven by an electric motor is used as throttle valve 113; however, other methods can also be used as long as the amount of airflow can be adjusted accordingly.

[0022] The temperature of the gas flowing into each cylinder 150 is measured by an intake air temperature sensor 115.

[0023] A crank angle sensor 121 is arranged on a radial outer surface of a ring gear 120 attached to a crankshaft 123. The crank angle sensor 121 detects the rotation angle of the crankshaft 123. In one embodiment, the crank angle sensor 121 detects the rotation angle of the crankshaft 123, for example, every 10° and every combustion cycle.

[0024] A water temperature sensor 122 is arranged on a water jacket (not shown) of a cylinder head. The water temperature sensor 122 detects the temperature of the coolant of the internal combustion engine 100.

[0025] Additionally, the vehicle is equipped with an accelerator pedal position sensor 126, which detects the amount of movement (amount of depression) of an accelerator pedal 125. The accelerator pedal position sensor 126 detects the torque requested by the driver. The torque requested by the driver, detected by the accelerator pedal position sensor 126, is output to the control device 1 described below. The control device 1 controls the throttle valve 113 based on the requested torque.

[0026] Fuel stored in a fuel tank 130 is drawn in and pressurized by a fuel pump 131. It then flows through a fuel line 133 equipped with a pressure regulator 132 and is subsequently directed to a fuel injector 134 (injector nozzle). The fuel dispensed by the fuel pump 131 is regulated to a predetermined pressure by the pressure regulator 132 and injected into each cylinder 150 by the fuel injector 134 (injector nozzle). Due to the pressure regulation performed by the pressure regulator 132, excess fuel is returned to the fuel tank 130 via a return line (not shown).

[0027] The cylinder head (not shown) of the internal combustion engine 100 is equipped with a combustion pressure sensor (cylinder pressure sensor, also referred to as cylinder pressure sensor) 140. The combustion pressure sensor 140 is located in each cylinder 150 and detects the pressure (combustion pressure) in the cylinder 150.

[0028] A piezoelectric pressure sensor or measuring pressure sensor is used as the combustion pressure sensor 140 and the combustion pressure sensor 140 can detect the combustion pressure in the cylinder 150 (cylinder internal pressure) over a wide temperature range.

[0029] Each cylinder 150 is equipped with an exhaust valve 152 and an exhaust manifold 160, which convey the combustion gases (exhaust gases) from the cylinder 150 to the outside. A three-way catalytic converter 161 is arranged on the exhaust side of the exhaust manifold 160.

[0030] When the exhaust valve 152 opens, exhaust gases from cylinder 150 are routed to the exhaust manifold 160. The exhaust gases are cleaned by the three-way catalytic converter 161 as they pass through the exhaust manifold 160 and are then released into the atmosphere.

[0031] An upstream air-fuel ratio sensor 162 is arranged 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 gases exiting each cylinder 150.

[0032] Additionally, a downstream air-fuel ratio sensor 163 is arranged on the downstream side of the three-way catalyst 161. The downstream air-fuel ratio sensor 163 outputs a switching-like detection signal in the vicinity of the theoretical air-fuel mixture. In one embodiment, the downstream air-fuel ratio sensor 163 is, for example, an O2 sensor.

[0033] Furthermore, a spark plug 200 is arranged above each cylinder 150. Due to the discharge (ignition) of the spark plug 200, the air-fuel mixture in cylinder 150 ignites, an explosion occurs in cylinder 150, and a piston 170 is forced downwards. When the piston 170 is forced downwards, the crankshaft 123 rotates.

[0034] An ignition coil 300, which generates electrical energy (voltage) supplied to the spark plug 200, is connected to the spark plug 200. That is, one ignition coil 300 is provided for each of the plurality of cylinders 150 (four cylinders in one embodiment) of the internal combustion engine 100. The voltage generated in the ignition coil 300 produces a discharge between the center electrode 210 and the outer electrode 220 of the spark plug 200 (see Fig. 2).

[0035] As in Fig. Figure 2 shows the center electrode 210 of the spark plug 200 in an insulated state, supported by an insulator 230. A predetermined voltage (for example, 20,000 V to 40,000 V in one embodiment) is applied to the center electrode 210.

[0036] The outer electrode 220 is grounded. When a predetermined voltage is applied to the center electrode 210, a discharge (ignition) occurs between the center electrode 210 and the outer electrode 220.

[0037] The voltage at which the discharge (ignition) occurs due to the dielectric breakdown of the gas component changes according to the state of the gas between the center electrode 210 and the outer electrode 220 of the spark plug 200 and the cylinder pressure. The voltage at which this discharge occurs is called the breakdown voltage.

[0038] The discharge control (ignition control) of the spark plug 200 is carried out by an ignition control unit 83 of the control device 1 as described below.

[0039] Out of Fig. Figure 1 shows that signals are output to the control device 1 from various sensors, such as the throttle opening sensor 113a, the flow rate sensor 114, the crankshaft angle sensor 121, the accelerator pedal position sensor 126, the water temperature sensor 122, and the combustion pressure sensor 140, as previously described. The control device 1 detects the operating state of the internal combustion engine 100 based on the signals output by these various sensors and controls the amount of air flowing into the cylinder 150, the amount of fuel injected, the ignition timing of the spark plug 200, and the like. [Hardware configuration of the control device]

[0040] The following describes the overall hardware configuration of control device 1.

[0041] As in Fig. As shown in Figure 1, the control device 1 comprises an analog input unit 10, a digital input unit 20, an analog / digital (A / D) converter 30, a random access memory (RAM) 40, a micro-processing unit (MPU) 50, a read only memory (ROM) 60, an input / output (I / O) port 70 and an output circuit 80.

[0042] Analog output signals from various sensors such as the throttle 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 to the analog input unit 10.

[0043] The A / D converter 30 is connected to the analog input unit 10. The analog output signals from various sensors, which are input to the analog input unit 10, are converted into digital signals by the A / D converter 30 after signal processing, such as noise reduction, has been performed, and stored in the RAM 40.

[0044] A digital output signal from the crank angle sensor 121 is output to the digital input unit 20.

[0045] The I / O port 70 is connected to the digital input unit 20 and the digital output signal entered at the digital input unit 20 is stored in the RAM 40 via the I / O port 70.

[0046] Each output signal stored in the 40 is processed arithmetically by the MPU 50.

[0047] The MPU 50 executes a control program (not shown) stored in ROM 60 to perform arithmetic processing on the output signals stored in RAM 40, according to the control program. The MPU 50 calculates control values ​​that define the actuation quantity of each actuator (for example, the throttle valve 113, the pressure regulator 132, the spark plug 200, and the like) that drives the internal combustion engine 100 according to the control program, and temporarily stores the calculated control values ​​in RAM 40.

[0048] The control values, which define the actuation quantity of the actuator stored in RAM 40, are output to the output circuit 80 via the I / O port 70.

[0049] The output circuit 80 is equipped with a function of an ignition control unit 83 (see Fig. 3) equipped, which controls a voltage applied to the spark plug 200. [Functional block of the control device]

[0050] The functional configuration of control device 1 is described below.

[0051] Fig. Figure 3 shows a functional block diagram to explain the functional configuration of the control device 1. Each function of the control device 1 is executed by the output circuit 80, for example by causing the MPU 50 to execute the control program stored in the ROM 60.

[0052] As in Fig. Figure 3 shows that the output circuit 80 of the control device 1 comprises a total control unit 81, a fuel injection control unit 82 and an ignition control unit 83.

[0053] The overall control unit 81 is connected to an accelerator pedal position sensor 126 and a combustion pressure sensor 140 and receives the requested torque (acceleration signal S1) from the accelerator pedal position sensor 126 and an output signal S2 from the combustion pressure sensor 140.

[0054] The overall control unit 81 performs the overall control of the fuel injection control unit 82 and the ignition control unit 83 on the basis of the requested torque (acceleration signal S1) from the accelerator pedal position sensor 126 and the output signal S2 from the combustion pressure sensor 140.

[0055] The fuel injection control unit 82 is connected to a cylinder discrimination unit 84, which distinguishes 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 discrimination information S3 from the cylinder discrimination 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.

[0056] Additionally, the fuel injection control unit 82 is connected to an intake air quantity measuring unit 87, which measures an intake air quantity drawn into the cylinder 150, a load information generation unit 88, which measures an engine load, and a water temperature measuring unit 89, which measures a temperature of an engine coolant, and receives an intake air quantity information S6 from the intake air quantity measuring unit 87, an engine load information S7 from the load information generation unit 88, and a coolant information S8 from the water temperature measuring unit 89.

[0057] The fuel injection control unit 82 calculates the injection quantity and injection timing of the fuel injected by the fuel injector 134 (fuel injector control information S9) on the basis of each received piece of information and controls the fuel injector 134 on the basis of the calculated fuel injection quantity and the calculated injection timing.

[0058] The ignition control unit 83 is connected to the cylinder differentiation 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 all information from these.

[0059] Based on each piece of information received, the ignition control unit 83 calculates the amount of current (excitation angle) that excites a primary coil (not shown) of the ignition coil 300, the excitation start time and the time to switch off the current excited in the primary coil (ignition time).

[0060] Based on the calculated excitation angle, the excitation start time, and the ignition timing, the ignition control unit 83 causes the spark plug 200 to perform discharge control (ignition control) by outputting the ignition signal SA to the primary coil 310 of the ignition coil 300 a multiple time. Thus, the spark plug 200 discharges multiple times. In one embodiment, the ignition control unit 83 controls the excitation of a single ignition coil 300 for each cylinder 150 with respect to the multiple cylinders 150 contained in the internal combustion engine 100 (four cylinders in one embodiment).

[0061] At least the function of the ignition control unit 83 for controlling the ignition of the spark plug 200 using the ignition signal SA corresponds to the control device for the internal combustion engine according to the present invention. [Electrical circuit of the ignition coil]

[0062] The electrical circuit 400, including the ignition coil 300, is described below.

[0063] Fig. Figure 4 shows a diagram to explain the electrical circuit 400 comprising the ignition coil 300. In the electrical circuit 400, the ignition coil 300 is designed to comprise a primary coil 310 wound with a predetermined number of windings and a secondary coil 320 wound with a greater number of windings than that of the primary coil 310.

[0064] One end of the primary coil 310 is connected to a DC power supply 330. A predetermined voltage (for example, 12 V in one embodiment) is thus applied to the primary coil 310. A charge quantity detection unit 350 is arranged in the 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 voltage and current to the ignition control unit 83.

[0065] The other end of the primary coil 310 is connected to an ignition electrode 340 and is grounded via the ignition electrode 340. A transistor, a field-effect transistor (FET), or the like is used in the ignition electrode 340.

[0066] A base (B) terminal of the ignition electrode 340 is connected to the ignition control unit 83. The ignition signal SA output by the ignition control unit 83 is input at the base (B) terminal of the ignition electrode 340. When the ignition signal SA is input at the base (B) terminal of the ignition electrode 340, a collector (C) terminal and an emitter (E) terminal of the ignition electrode 340 are energized, and current flows between the collector (C) terminal and the emitter (E) terminal. Thus, the ignition signal SA is output by the ignition control unit 83 to the primary coil 310 of the ignition coil 300 via the ignition electrode 340, and current (electrical energy) is stored in the primary coil 310.

[0067] When the ignition signal Sa is stopped by the ignition control unit 83 and the current flowing through the primary coil 310 is switched off, a high voltage corresponding to a coil winding ratio with respect to the primary coil 310 is generated in the secondary coil 320. When the high voltage generated in the secondary coil 320 is applied to the spark plug 200 (center electrode 210), a potential difference is generated 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 greater than or equal to a dielectric breakdown voltage Vm of the gas (air-fuel mixture in cylinder 150), a dielectric breakdown occurs in the gas component, a discharge takes place between the center electrode 210 and the outer electrode 220, and the fuel (air-fuel mixture) is ignited.

[0068] A discharge quantity detection unit 360 is arranged in the connection path between the secondary coil 320 and the spark plug 200. The discharge quantity detection unit 360 detects the discharge voltage and current and sends the discharge voltage and current to the ignition control unit 83.

[0069] The ignition control unit 83 controls the excitation of the ignition coil 300 using the ignition signal SA by operating the electrical circuit 400 as described above. Thus, the electrical energy supplied by the ignition coil 300 to the spark plug 200 is controlled, and the ignition control for multiple discharges of the spark plug 200 is carried out. [Overview of multiple discharges]

[0070] The following is an overview of the multiple discharge of the spark plug 200 according to one embodiment.

[0071] Fig. Figure 5 shows a schematic diagram illustrating an example of the multiple discharge method according to an embodiment of the present invention. A target charge quantity for the ignition coil 300 is determined by an engine speed (ignition cycle) or a charging voltage.

[0072] In the multiple discharge method according to one embodiment, the ignition control unit 83 determines the target charge quantity of the ignition coil 300 according to the engine speed (ignition cycle) or the charging voltage with respect to a predetermined map information and outputs the ignition signal SA to the ignition coil 300 (ignition electrode 340). At this time, the ignition control unit 83 continuously outputs two pulses as the ignition signal SA, so that the electrical energy for dielectric breakdown to apply a dielectric breakdown voltage between the electrodes of the spark plug 200 and the electrical energy for ignition maintenance to maintain the discharge (ignition) of the spark plug 200 are divided and supplied by the ignition coil 300 to the spark plug 200.

[0073] Specifically, when the ignition signal SA is switched from OFF to ON at time T1, the charging of the ignition coil 300 is initiated and electrical energy is accumulated in the ignition coil 300. At this time, the ignition control unit 83 calculates the charge quantity (input energy) of the ignition coil 300 by integrating the charging power value determined from the voltage and current of the primary coil 310, as measured by the charge quantity detection unit 350 at predetermined time intervals. When the charge quantity reaches the specified target charge quantity (e.g., 110 mJ) at time T2, the ignition signal SA is switched from ON to OFF, thus interrupting the charging of the ignition coil 300 and initiating the supply of electrical energy from the ignition coil 300 to the spark plug 200. This electrical energy causes the first discharge between the electrodes of the spark plug 200.

[0074] When the supply of electrical energy from ignition coil 300 to spark plug 200 has started and spark plug 200 is discharging, the ignition control unit 83 calculates the discharge quantity (output energy) of ignition coil 300 by integrating the discharge power determined from the voltage and current of the secondary coil 320, detected by the discharge quantity detection unit 360 at predetermined time intervals. When the discharge quantity reaches the previously described electrical energy for dielectric breakdown (for example, 30 mJ) at time T3, the ignition signal SA is switched from OFF to ON, so that the supply of electrical energy from ignition coil 300 to spark plug 200 is stopped and charging of ignition coil 300 continues.

[0075] Subsequently, when a predetermined time has elapsed from time T3 and time T4 has been reached, the ignition control unit 83 switches the ignition signal SA from ON to OFF, thus interrupting the charging of the ignition coil 300 and continuing the supply of electrical energy from the ignition coil 300 to the spark plug 200. Due to this electrical energy, the second discharge occurs in a state in which the dielectric breakdown between the electrodes of the spark plug 200 is maintained.

[0076] After the second discharge, the ignition signal SA is held in the OFF position, so that the remaining electrical energy (for example, 80 mJ) stored in the ignition coil 300 is supplied to the spark plug 200 as the previously described electrical energy for maintaining ignition. When all the electrical energy of the ignition coil 300 is released at time T5, the multiple discharges of the spark plug 200 are terminated according to one embodiment. At this point, the time from time T2, when the first discharge begins, to time T5, when the second discharge ends, is, for example, approximately 2 ms. [Spark plug tax procedure]

[0077] The following is an example of the procedure for controlling the spark plug 200 by the ignition control unit 83. Fig. Figure 6 shows an example of a flow diagram to explain the method for controlling the spark plug 200 by the ignition control unit 83 according to one embodiment.

[0078] As in Fig. As shown in Figure 6, in step S101, the ignition control unit 83 determines the amount of electrical energy required for dielectric breakdown to generate a discharge between the electrodes of the spark plug 200. For example, the air-fuel ratio in cylinder 150 is estimated based on the air-fuel mixture of the exhaust gases, detected by the upstream air-fuel ratio sensor 162, and the amount of electrical energy required for dielectric breakdown is set to be smaller when the air-fuel ratio is lower (when the mixture is richer). Furthermore, for example, based on the pressure detected by the combustion pressure sensor 140 in cylinder 150, the amount of electrical energy required for dielectric breakdown is set to be smaller when the pressure is lower.The amount of electrical energy required for dielectric breakdown according to the air-fuel ratio or the pressure in cylinder 150 is determined, for example, by reference to the map information stored in the ROM 60 of the control device 1.

[0079] In step S102, the ignition control unit 83 determines the amount of electrical energy required for ignition maintenance to maintain the discharge between the electrodes of the spark plug 200. Here, as with the amount of electrical energy for dielectric breakdown in step S101, the air-fuel ratio in cylinder 150 is estimated based on the air-fuel mixture of the exhaust gases, detected by the upstream air-fuel ratio sensor 162. The amount of electrical energy required for ignition maintenance is set lower when the air-fuel ratio is lower (when the mixture is richer). Furthermore, for example, based on the pressure detected by the combustion pressure sensor 140 in cylinder 150, the amount of electrical energy required for ignition maintenance is set lower when the pressure is lower.The amount of electrical energy for maintaining ignition according to the air-fuel ratio or the pressure in cylinder 150 is determined, for example, by reference to the map information stored in the ROM 60 of the control device 1.

[0080] In step S103, the ignition control unit 83 sets the target charge quantity for the ignition coil 300. Here, the amount of electrical energy for dielectric breakdown, set in step S101, and the amount of electrical energy for ignition maintenance, set in step S102, are added, and the total value is set as the target charge quantity. At this point, as a countermeasure against variations in the charge quantity in the ignition coil 300, a certain margin for the target charge quantity can be expected, and the target charge quantity can be set by adding this margin to the previous total value. For example, 1.1 times the previous total value can be set as the target charge quantity.In this way, in steps S106 to S109 as described above, before the ignition coil 300 begins supplying electrical energy to the spark plug 200, the excitation of the ignition coil 300 can be controlled such that the amount of energy collected in the ignition coil 300 is greater than or equal to the total value of the amount of electrical energy for the dielectric breakdown and the amount of electrical energy for maintaining ignition.

[0081] In step S104, the ignition control unit 83 sets the charging start time of the ignition coil 300 based on the target charging quantity determined in step S103.

[0082] In step S105, the ignition control unit 83 determines whether to begin charging the ignition coil 300, based on the charging start time specified in step S104. Step S105 is repeated until it is determined that charging should begin (step S105: NO), and if it is determined that charging should begin (step S105: YES), the process continues with step S106.

[0083] In step S106, the ignition control unit 83 switches on the pulse of the ignition signal SA and starts charging the ignition coil 300. Electrical energy is collected in the primary coil 310 of the ignition coil 300 in response to the output of the ignition signal SA.

[0084] In step S107, the ignition control unit 83 detects the current charge quantity (input energy) of the ignition coil 300 based on the voltage and current detection results of the primary coil 310 by the charge quantity detection unit 350.

[0085] In step S108, the ignition control unit 83 compares the target charge quantity set in step S103 with the actual charge quantity detected in step S107 and determines whether the charge quantity of ignition coil 300 has reached the target charge quantity or not. Thus, until it is determined that the charge quantity of ignition coil 300 has reached the target charge quantity (step S108: NO), the process returns to step S107 to continue detecting the charge quantity, and if it is determined that the target charge quantity has been reached (step S108: YES), the process continues with step S109.

[0086] In step S109, the ignition control unit 83 switches off the pulse of the ignition signal SA and interrupts the charging of the ignition coil 300. The electrical energy stored in the ignition coil 300 is supplied by the secondary coil 320 to the spark plug 200 in response to the cessation of the output of the ignition signal SA. Thus, the ignition control unit 83 causes the ignition coil 300 to begin supplying electrical energy to the spark plug 200.

[0087] In step S110, the ignition control unit 83 detects the actual discharge quantity (output energy) of the ignition coil 300 based on the voltage and current sensing results of the secondary coil 320 by the discharge quantity sensing unit 360. Through this process, the ignition control unit 83 begins to cause the ignition coil 300 to deliver the electrical energy to the spark plug 200 in step S109, and subsequently calculates the total quantity of electrical energy delivered.

[0088] In step S111, ignition control unit 83 compares the amount of electrical energy for dielectric breakdown specified in step S101 with the actual discharge amount recorded in step S110 and determines whether the discharge amount of the ignition coil 300 is greater than or equal to the amount of electrical energy for dielectric breakdown or not.

[0089] Thus, the process returns to step S110 to continue measuring the discharge quantity until the discharge quantity of the spark plug 300 becomes greater than or equal to the amount of electrical energy for the dielectric breakdown (step S111: NO), and when it is determined that the discharge quantity of the ignition coil 300 is greater than or equal to the amount of electrical energy for the dielectric breakdown (step S111: YES), the process continues with step S112.

[0090] In step S112, the ignition control unit 83 activates the pulse of the ignition signal SA and continues charging the ignition coil 300. The electrical energy is collected in the primary coil 310 of the ignition coil 300 in response to the output of the ignition signal SA, and the ignition coil 300 is charged.

[0091] In step S113, the ignition control unit 83 determines whether a predetermined time (e.g., approximately 30 µs) has elapsed after the ignition signal pulse SA is switched on in step S112. Step S113 is repeated until the predetermined time has elapsed (step S113: NO), and if it is determined that the predetermined time has elapsed (step S113: YES), the process continues with step S114.

[0092] In step S114, the ignition control unit 83 switches off the pulse of the ignition signal SA and stops charging the ignition coil 300. The remaining electrical energy stored in the ignition coil 300 is supplied by the secondary coil 320 to the spark plug 200 in response to the cessation of the ignition signal SA output. The remaining charge (remaining amount of energy) of the ignition coil 300 at this point is at least greater than the amount of electrical energy required for ignition maintenance as determined in step S102.

[0093] Subsequently, after the ignition coil 300 begins charging in step S112, the ignition control unit 83 causes the ignition coil 300 to supply the spark plug 200 with electrical energy greater than or equal to the amount of electrical energy required to maintain ignition. When the output of the ignition signal SA is stopped in step S114, the processing sequence of Fig. 6 completed.

[0094] According to the embodiments described above, the following effects are achieved.

[0095] (1) The control device 1 for the internal combustion engine comprises the ignition control unit 83, which controls the excitation of the ignition coil 300, which supplies electrical energy to the spark plug 200, which performs a discharge in the cylinder 150 of the internal combustion engine 100 to ignite the fuel. The ignition control unit 83 determines the amount of electrical energy for dielectric breakdown (first amount of electrical energy) to generate a discharge between the electrodes of the spark plug 200 and the amount of electrical energy for ignition maintenance (second amount of electrical energy) to maintain the discharge (steps S101 and S102). After the ignition coil 300 begins supplying electrical energy to the spark plug 200 (step S109), the ignition control unit 83 calculates the total amount of electrical energy supplied (step S110).When the calculated total amount of electrical energy is greater than or equal to the first amount (step S111: YES), the ignition control unit 83 controls the excitation of the ignition coil 300 so that the ignition coil 300 is charged (step S112). After the ignition coil 300 is charged, the ignition control unit 83 controls the excitation of the ignition coil 300 so that electrical energy greater than or equal to the second amount of electrical energy is delivered from the ignition coil 300 to the spark plug 200 (step S114). In this way, the ignitability of the fuel by the spark plug 200 can be effectively improved.

[0096] (2) In steps S101 and S102, since the air-fuel ratio in cylinder 150 of the internal combustion engine 100 is smaller, the amount of electrical energy for dielectric breakdown (first amount of electrical energy) and the amount of electrical energy for ignition maintenance (second amount of electrical energy) are set to be smaller.

[0097] Furthermore, since the pressure in cylinder 150 of the internal combustion engine 100 is lower, the amount of electrical energy required for dielectric breakdown (first amount of electrical energy) and the amount of electrical energy required for ignition maintenance (second amount of electrical energy) are set to be smaller. In this way, a suitable amount of electrical energy can be determined according to the state of the air-fuel mixture in the internal combustion engine 100.

[0098] (3) Before the ignition coil 300 begins supplying electrical energy to the spark plug 200, the ignition control unit 83 controls the excitation of the ignition coil 300 such that the amount of energy stored in the ignition coil 300 is greater than or equal to the total value of the amount of electrical energy for dielectric breakdown (first amount of electrical energy) and the amount of electrical energy for ignition maintenance (second amount of electrical energy) (steps S103 and S106 to S109). In this way, a sufficient amount of electrical energy can be stored in the ignition coil 300 before the first discharge of the spark plug 200 so that several discharges of the spark plug 200 can be carried out.

[0099] (4) The internal combustion engine 100 has a plurality of cylinders 150, and an ignition coil 300 is provided for each of the plurality of cylinders 150. The ignition control unit 83 controls the excitation of the individual ignition coil 300 for each cylinder 150. In this way, multiple discharges of the spark plug 200 can occur without increasing the size of the ignition coil 300.

[0100] In the embodiment described above, any functional configuration of the features relating to Fig. The control device 1 described in section 3 can be implemented by software executed by the MPU 50 as described above, or it can be implemented by hardware, such as a Field Programmable Gate Array (FPGA). These methods can also be combined and used together.

[0101] Furthermore, the embodiment describes a case in which the spark plug 200 is discharged twice; however, the present invention is not limited to this, and the number of discharges can be three or more. That is, the ignition control unit 83 can control the excitation of the ignition coil 300 such that the ignition coil 300 supplies the spark plug 200 with electrical energy a multitude of times, in order to make the total electrical energy supplied greater than or equal to the amount of electrical energy required for ignition maintenance. For example, it is assumed that the target charge quantity is 110 mJ as previously described, and that 30 mJ of electrical energy is supplied from the ignition coil 300 to the spark plug 200 as electrical energy for the dielectric breakdown in the first discharge.In this case, 80 mJ, which is the remaining amount of electrical energy stored in ignition coil 300, is divided into two parts, namely 40 mJ, and supplied by ignition coil 300 to spark plug 200 as electrical energy to maintain ignition. Thus, spark plug 200 can perform the second and third discharges.

[0102] This also applies to the case of performing the fourth discharge and any subsequent discharges. This allows for more detailed discharge control.

[0103] The embodiments or various modifications described above are purely exemplary, and the present invention is not limited to these, provided that the features of the present invention are not impaired. Furthermore, although various embodiments or modifications have been described above, the present invention is not limited to these. Other aspects conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention. Reference symbol list 1 Control device 10 analog input units 20 digital input units 30 A / D converters 40 RAM 50 MPU 60 ROM 70 I / O connector 80 distribution area 81 Total control unit 82 Fuel injection control unit 83 Ignition control unit 84 Cylinder discrimination unit 85 Angle Information Generation Unit 86 Speed ​​Information Generation Unit 87 Intake air volume measuring unit 88 Load Information Generation Unit 89 Water temperature measuring unit 100 internal combustion engine 110 air filters 111 Intake manifold 112 Intake manifold 113 Throttle valve 113a Throttle opening degree sensor 114 Flow rate sensor 115 Intake air temperature sensor 120 toothed ring 121 Crank angle sensor 122 Water temperature sensor 123 Crankshaft 125 accelerator pedal 126 Accelerator pedal position sensor 130 fuel tank 131 Fuel pump 132 pressure regulators 133 Fuel line 134 Fuel injector 140 Combustion pressure sensor 150 cylinders 151 Intake valve 152 Exhaust valve 160 exhaust manifold 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 Ignition coil 310 Primary coil 320 Secondary coil 330 DC power supply 340 Ignition electrode 350 Load quantity recording unit 360° unloading quantity recording unit 400 electrical circuits

Claims

[1] Control device for an internal combustion engine, comprising: an ignition control unit, which controls the excitation of an ignition coil that supplies electrical energy to a spark plug, which performs a discharge in a cylinder of the internal combustion engine and ignites fuel, wherein the ignition control unit specifies a first quantity of electrical energy to generate a discharge between the electrodes of the spark plug and a second quantity of electrical energy to maintain the discharge, After the ignition coil begins to supply electrical energy to the spark plug, the ignition control unit calculates a total amount of electrical energy supplied, and when the calculated total amount becomes greater than or equal to the initial amount of electrical energy, the ignition control unit controls the excitation of the ignition coil so that the ignition coil is charged, and After the ignition coil is charged, the ignition control unit controls the excitation of the ignition coil so that electrical energy greater than or equal to the second amount of electrical energy is delivered from the ignition coil to the spark plug. [2] Control device for an internal combustion engine according to claim 1, wherein the first quantity of electrical energy and the second quantity of electrical energy are set to be smaller when the air-fuel ratio in the cylinder of the internal combustion engine is smaller. [3] Control device for an internal combustion engine according to claim 1, wherein the first quantity of electrical energy and the second quantity of electrical energy are set to be smaller when the pressure in the cylinder of the internal combustion engine is smaller. [4] Control device for an internal combustion engine according to claim 1, wherein, before the ignition coil begins to supply electrical energy to the spark plug, the ignition control unit controls the excitation of the ignition coil such that a quantity of electrical energy collected in the ignition coil is greater than or equal to a total value of the first quantity of electrical energy and the second quantity of electrical energy. [5] Control device for an internal combustion engine according to claim 1, wherein the internal combustion engine has a plurality of cylinders, an ignition coil is provided for each of the plurality of cylinders and the ignition control unit controls the excitation of a single ignition coil for each cylinder. [6] Control device for an internal combustion engine according to claim 1, wherein, after the ignition coil is charged, the ignition control unit controls the excitation of the ignition coil such that electrical energy is supplied from the ignition coil to the spark plug a plurality of times in order to make the total electrical energy supplied such that it is greater than or equal to the second quantity of electrical energy.

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