Control device for internal combustion engines

Abstract

This invention can suppress poor ignition of fuel by spark plugs and simultaneously suppress electrode wear of spark plugs in internal combustion engines. The control device for internal combustion engines of this invention includes an ignition control unit that controls the energization of an ignition coil to provide a first electrical energy to a spark plug and a second electrical energy superimposed on the first electrical energy, wherein the spark plug ignites fuel by discharging within the cylinder of the internal combustion engine. The ignition control unit sets a period from the start of the release of the first electrical energy from the spark plug to the start of the release of the second electrical energy based on the gas state surrounding the spark plug, and controls the energization of the ignition coil such that the first electrical energy is released from the spark plug, and the second electrical energy is released superimposed on the first electrical energy after the period has elapsed.

Description

[0001] This application is a divisional application of international application number PCT / JP2020 / 023521, which entered the Chinese national phase on December 8, 2021, and has application number 202080042286.3. Technical Field

[0002] This invention relates to a control device for internal combustion engines. Background Technology

[0003] In recent years, in order to improve vehicle fuel efficiency, control devices for internal combustion engines have been developed, such as those that use a mixture leaner than the stoichiometric air-fuel ratio to operate the engine and those that introduce a portion of the exhaust gases after combustion for re-intake.

[0004] In the control device of this type of internal combustion engine, because the amount of fuel and air in the combustion chamber deviates from the theoretical value, poor ignition of fuel by the spark plug is prone to occur. Therefore, there are methods to increase the flow rate between the spark plug electrodes by increasing the gas flow rate in the combustion chamber, thereby forming a longer discharge path, extending the contact length between the discharge path and the gas, and suppressing poor ignition.

[0005] However, increasing the flow rate between the spark plug electrodes increases the frequency of extinguishing the discharge path and the resulting re-discharge. During re-discharge, insulation breakdown occurs due to capacitive discharge. Because the current density of capacitive discharge is high, electrode melting due to high current occurs, accelerating electrode wear.

[0006] To reduce the frequency of capacitor discharge and suppress spark plug electrode wear, it is necessary to maintain the discharge path for as long as possible by continuously supplying a sufficient current after the discharge path is formed. However, in general, the internal energy of the ignition coil continuously decreases over time from the start of discharge, and therefore gradually becomes insufficient to supply the current required to maintain the discharge path.

[0007] As a result, the discharge path can no longer be maintained during gas combustion, and re-discharge is required.

[0008] Patent Document 1 discloses a control device for an internal combustion engine that uses an ignition coil having a main primary coil and an auxiliary primary coil, and superimposes current using the auxiliary primary coil during the period from the time a discharge spark occurs in the spark plug using the main primary coil until the superimposed current is applied for a period of time determined by taking into account the sufficient time necessary for the spark plug to discharge.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent No. 6375452 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] In the technology disclosed in Patent Document 1, because the superimposed current energizing time is fixed regardless of the combustion state, it is impossible to appropriately adjust the superimposed current energizing time to correspond with the cyclical variations of the internal combustion engine. To cope with cyclical variations, a superimposed current energizing time with an excessively large margin needs to be set. However, setting the superimposed current energizing time in this way results in a superimposed current flowing beyond the amount required to maintain the discharge path, leading to problems such as ignition coil heating, spark plug electrode wear, and reduced energy efficiency. Conversely, reducing the margin of the superimposed current energizing time may result in the ignition coil's internal energy decreasing, potentially making it impossible to maintain the discharge path.

[0014] Therefore, the present invention is derived with regard to the above-mentioned problems, and aims to suppress the poor ignition of gas by the spark plug, while suppressing the electrode wear of the spark plug in the internal combustion engine.

[0015] Technical solutions for solving the problem

[0016] The control device for an internal combustion engine of the present invention includes an ignition control unit that controls the energization of an ignition coil that provides electrical energy to a spark plug, wherein the spark plug discharges in the cylinder of the internal combustion engine to ignite fuel. The ignition control unit controls the energization of the ignition coil such that a first electrical energy is released from the ignition coil and a second electrical energy is released in addition to the first electrical energy. Furthermore, the energization of the ignition coil is controlled such that the release of the second electrical energy is stopped at an opportune moment when the gas state around the spark plug changes, thereby stopping the discharge of the spark plug.

[0017] Invention Effects

[0018] According to the present invention, it is possible to suppress poor ignition of gas by the spark plug, and at the same time suppress electrode wear of the spark plug in the internal combustion engine. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating the main structural components of the internal combustion engine and its control device in the embodiment.

[0020] Figure 2 This is a magnified view of a part of the spark plug.

[0021] Figure 3 This is a functional block diagram illustrating the functional structure of the control device in the implementation method.

[0022] Figure 4 It is a diagram illustrating the relationship between the operating state of an internal combustion engine and the gas flow rate around the spark plug.

[0023] Figure 5 It is a diagram illustrating the relationship between the discharge path and flow rate between the electrodes of a spark plug.

[0024] Figure 6 It is a diagram illustrating an existing circuit that includes an ignition coil.

[0025] Figure 7 This is an example of a timing diagram illustrating the relationship between the control signal input to the ignition coil and the output in existing discharge control.

[0026] Figure 8 This is a diagram illustrating the circuit including the ignition coil according to the first embodiment.

[0027] Figure 9 This is an example of a timing diagram illustrating the relationship between the control signal input to the ignition coil and the output in the discharge control of the first embodiment.

[0028] Figure 10 This is another example of a timing diagram illustrating the relationship between the control signal input to the ignition coil and the output in the discharge control of the first embodiment.

[0029] Figure 11 This is an example of a flowchart illustrating the control method of the ignition coil in the first embodiment.

[0030] Figure 12 This is a diagram illustrating an example of mapping information showing the relationship between the gas flow rate between the electrodes and a first set value and a second set value.

[0031] Figure 13 This is a diagram illustrating the circuit including the ignition coil in the second embodiment.

[0032] Figure 14 This is an example of a flowchart illustrating the control method of the ignition coil in the second embodiment.

[0033] Figure 15 This is a diagram illustrating an example of the mapping information showing the relationship between the gas flow rate between the electrodes and the pulse width of the ignition signal.

[0034] Figure 16 This is a diagram illustrating an example of a mapping of information showing the relationship between the gas flow rate between the electrodes and the period until the ignition signal is output.

[0035] Figure 17 This is a diagram illustrating the circuit including the ignition coil in the third embodiment. Detailed Implementation

[0036] The following describes a control device for an internal combustion engine according to an embodiment of the present invention.

[0037] The following describes one embodiment of the control device for an internal combustion engine, namely, a control device 1. In this embodiment, an example is given of the control device 1 controlling the discharge (ignition) of spark plugs 200 respectively installed in each cylinder 150 of a four-cylinder internal combustion engine 100.

[0038] In the following embodiments, the part consisting of a portion or all of the structure of the internal combustion engine 100 and a portion or all of the structure of the control device 1 is referred to as the control device 1 of the internal combustion engine 100.

[0039] [internal combustion engine]

[0040] Figure 1 This is a diagram illustrating the main structural components of the internal combustion engine 100 and the ignition device for the internal combustion engine.

[0041] Figure 2 This is a magnified view of the electrodes 210 and 220 of spark plug 200.

[0042] In the internal combustion engine 100, air drawn from the outside flows through the air filter 110, intake manifold 111, and intake manifold 112, and flows into each cylinder 150 when the intake valve 151 is open. The amount of air flowing into each cylinder 150 is adjusted by the throttle valve 113, and the amount of air adjusted by the throttle valve 113 is measured by the flow sensor 114.

[0043] A throttle opening sensor 113a is provided in the throttle valve 113 to detect the throttle opening degree. The opening degree information of the throttle valve 113 detected by the throttle opening sensor 113a is output to the control unit (Electronic Control Unit: ECU) 1.

[0044] Alternatively, throttle valve 113 uses an electronic throttle valve driven by an electric motor, but other types are possible as long as the airflow can be adjusted appropriately.

[0045] The temperature of the gas flowing into each cylinder 150 is detected by an intake air temperature sensor 115.

[0046] A crank angle sensor 121 is disposed radially outside the ring gear 120 mounted on the crankshaft 123. This crank angle sensor 121 detects the rotation angle of the crankshaft 123. In an embodiment, the crank angle sensor 121 detects, for example, the rotation angle of the crankshaft 123 every 10° and every combustion cycle.

[0047] A water temperature sensor 122 is installed in the water jacket (not shown) of the cylinder head. This water temperature sensor 122 is used to detect the temperature of the cooling water in the internal combustion engine 100.

[0048] Additionally, an Accelerator Position Sensor (APS) 126 is installed in the vehicle to detect the displacement (application amount) of the accelerator pedal 125. This APS 126 detects the driver's desired torque. The driver's desired torque detected by the APS 126 is output to the control device 1, described later. The control device 1 controls the throttle valve 113 based on this desired torque.

[0049] Fuel stored in fuel container 130, after being drawn and pressurized by fuel pump 131, flows through fuel piping 133 equipped with pressure regulator 132 and is directed to fuel injection valve 134. Fuel output from fuel pump 131 is adjusted to a specified pressure by pressure regulator 132 and injected into each cylinder 150 from fuel injection valve 134. After pressure adjustment by pressure regulator 132, excess fuel returns to fuel container 130 via return piping (not shown).

[0050] A combustion pressure sensor (CPS, also known as an in-cylinder pressure sensor) 140 is installed in the cylinder head (not shown) of the internal combustion engine 100. The combustion pressure sensor 140 is installed in each cylinder 150 to detect the pressure (combustion pressure) in the cylinder 150.

[0051] The combustion pressure sensor 140 uses a piezoelectric or strain gauge pressure sensor and is able to detect the combustion pressure (cylinder pressure) inside the cylinder 150 over a wide temperature range.

[0052] Each cylinder 150 is equipped with an exhaust valve 152 and an exhaust manifold 160 that discharges the combustion gases (exhaust gases) to the outside of the cylinder 150. A triple-effect catalyst 161 is installed on the exhaust side of the exhaust manifold 160. When the exhaust valve 152 is open, exhaust gases are discharged from the cylinder 150 into the exhaust manifold 160. These exhaust gases are purified by the exhaust manifold 160 and the triple-effect catalyst 161 before being discharged into the atmosphere.

[0053] An upstream air-fuel ratio sensor 162 is provided on the upstream side of the three-way catalyst 161. This upstream air-fuel ratio sensor 162 continuously detects the air-fuel ratio of the exhaust gases discharged from each cylinder 150.

[0054] Additionally, a downstream air-fuel ratio sensor 163 is provided downstream of the three-way catalyst 161. This downstream air-fuel ratio sensor 163 outputs a switching detection signal near the stoichiometric air-fuel ratio. In this embodiment, the downstream air-fuel ratio sensor 163 is, for example, an O2 sensor.

[0055] Additionally, spark plugs 200 are installed on the upper part of each cylinder 150. The spark plugs 200 discharge (ignite) the air-fuel mixture inside the cylinder 150, causing an explosion that pushes down the piston 170. This pushes down the piston 170, causing the crankshaft 123 to rotate.

[0056] For spark plug 200, an ignition coil 300 is connected to generate electrical energy (voltage) supplied to spark plug 200. The voltage generated in the ignition coil 300 causes a discharge between the center electrode 210 and the outer electrode 220 of spark plug 200 (see reference). Figure 2 ).

[0057] like Figure 2 As shown, in spark plug 200, center electrode 210 is supported in an insulated state by insulator 230. A specified voltage (e.g., 20,000V to 40,000V in the embodiment) is applied to center electrode 210.

[0058] The outer electrode 220 is grounded. When a specified voltage is applied to the center electrode 210, a discharge (ignition) occurs between the center electrode 210 and the outer electrode 220.

[0059] Furthermore, in spark plug 200, the voltage that causes the insulation breakdown of the gas components to generate a discharge (ignition) varies depending on the state of the gas between the center electrode 210 and the outer electrode 220 and the cylinder pressure. This voltage that generates the discharge is called the insulation breakdown voltage.

[0060] The discharge control (ignition control) of the spark plug 200 is performed by the ignition control unit 83 of the control device 1, which will be described later.

[0061] return Figure 1 The output signals from various sensors, including the throttle opening sensor 113a, flow sensor 114, crank angle sensor 121, acceleration position sensor 126, water temperature sensor 122, and combustion pressure sensor 140, are output to the control device 1. In the control device 1, based on these output signals from various sensors, the operating state of the internal combustion engine 100 is detected, and control is performed on the amount of air delivered to the cylinder 150, the amount of fuel injected, and the ignition timing of the spark plug 200.

[0062] [Hardware Structure of the Control Device]

[0063] Next, the overall structure of the hardware of control device 1 will be explained.

[0064] like Figure 1As shown, the control device 1 includes an analog input unit 10, a digital input unit 20, an A / D (Analog / Digital) converter 30, a RAM (Random Access Memory) 40, an MPU (Micro-Processing Unit) 50, a ROM (ReadOnly Memory) 60, an I / O (Input / Output) port 70, and an output circuit 80.

[0065] The analog input unit 10 receives analog output signals from various sensors, including the throttle opening sensor 113a, the flow sensor 114, the acceleration 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.

[0066] The analog input unit 10 is connected to the A / D converter 30. After performing signal processing such as noise removal on the analog output signals from various sensors input to the analog input unit 10, the A / D converter 30 converts them into digital signals and stores them in the RAM 40.

[0067] The digital input unit 20 receives a digital output signal from the crank angle sensor 121.

[0068] The digital input unit 20 is connected to the I / O port 70, and the digital output signal input to the digital input unit 20 is stored in the RAM 40 via the I / O port 70.

[0069] The output signals stored in RAM40 are processed by MPU50.

[0070] MPU50 executes the control program (not shown) stored in ROM60, and processes the output signals stored in RAM40 according to the control program. MPU50 calculates the control values ​​of the operating quantities of each actuator (e.g., throttle valve 113, pressure regulator 132, spark plug 200, etc.) that drive the internal combustion engine 100 according to the control program, and temporarily stores them in RAM40.

[0071] The control values ​​for the specified actuator operation stored in RAM40 are output to the output circuit 80 via I / O port 70.

[0072] In the output circuit 80, an ignition control unit 83 is provided to control the voltage applied to the spark plug 200 (see reference). Figure 3 (functions, etc.)

[0073] [Functional modules of the control device]

[0074] Next, the functional structure of the control device 1 according to an embodiment of the present invention will be described.

[0075] Figure 3 This is a functional block diagram illustrating the functional structure of a control device 1 according to one embodiment of the present invention. The functions of the control device 1 are implemented, for example, by the output circuit 80 executing the control program stored in the ROM 60 via the MPU 50.

[0076] like Figure 3 As shown, the output circuit 80 of the control device 1 in the first embodiment includes an overall control unit 81, a fuel injection control unit 82, and an ignition control unit 83.

[0077] The overall control unit 81 is connected to the acceleration position sensor 126 and the combustion pressure sensor 140 (CPS), and receives the required torque (acceleration signal S1) from the acceleration position sensor 126 and the output signal S2 from the combustion pressure sensor 140.

[0078] The overall control unit 81 performs overall control of the fuel injection control unit 82 and the ignition control unit 83 based on the required torque (acceleration signal S1) from the acceleration position sensor 126 and the output signal S2 from the combustion pressure sensor 140.

[0079] The fuel injection control unit 82 is connected to the cylinder discrimination unit 84 that discriminates each cylinder 150 of the internal combustion engine 100, the angle information generation unit 85 that measures the crankshaft angle of the crankshaft 123, and the speed information generation unit 86 that measures the engine speed. It 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.

[0080] In addition, the fuel injection control unit 82 is connected to the intake air volume measuring unit 87, which measures the intake air volume into the cylinder 150, the load information generation unit 88, which measures the engine load, and the water temperature measuring unit 89, which measures the engine coolant temperature. It receives intake air volume information S6 from the intake air volume measuring unit 87, engine load information S7 from the load information generation unit 88, and coolant temperature information S8 from the water temperature measuring unit 89.

[0081] Based on the received information, the fuel injection control unit 82 calculates the injection quantity and injection time of the fuel injected from the fuel injection valve 134 (fuel injection valve control information S9), and controls the fuel injection valve 134 based on the calculated fuel injection quantity and injection time.

[0082] In addition to the overall control unit 81, the ignition control unit 83 is also connected to the cylinder discrimination 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, and receives information from them.

[0083] Based on the received information, the ignition control unit 83 calculates the current (energizing angle) energizing the primary coil (not shown) of the ignition coil 300, the energizing start time, and the time to cut off the current energizing the primary coil (ignition time).

[0084] Based on the calculated energizing angle, energizing start time, and ignition time, the ignition control unit 83 outputs an ignition signal SA to the primary coil of the ignition coil 300, thereby controlling the discharge of the spark plug 200 (ignition control).

[0085] In addition, at least the ignition control unit 83 uses the ignition signal SA to control the ignition of the spark plug 200, which is equivalent to the control device for internal combustion engines of the present invention.

[0086] Figure 4 This is a graph illustrating the relationship between the operating state of the internal combustion engine 100 and the gas flow velocity around the spark plug 200. (Example) Figure 4 As shown, generally speaking, the higher the engine speed and load, the higher the gas flow rate within cylinder 150, and the higher the gas flow rate around spark plug 200. Therefore, gas flows at a high speed between the center electrode 210 and the outer electrode 220 of spark plug 200. Furthermore, in an internal combustion engine 100 that performs exhaust gas recirculation (EGR), the relationship with engine speed and load is correspondingly as follows, for example... Figure 4 The EGR rate is set as shown. In addition, the wider the EGR rate is set to the higher EGR range, the more fuel consumption and emissions can be reduced, but poor ignition is more likely to occur with spark plug 200.

[0087] Figure 5 This is a diagram illustrating the relationship between the discharge path and flow rate between the electrodes of spark plug 200.

[0088] A high voltage is generated in the secondary coil of the ignition coil 300. When insulation breaks between the center electrode 210 and the outer electrode 220 of the spark plug 200, a discharge path is formed between the electrodes of the spark plug 200 during the period until the current flowing between these electrodes falls below a certain value. When combustible gas comes into contact with this discharge path, a flame nucleus grows, leading to combustion. The discharge path is affected by the gas flow between the electrodes and moves accordingly; therefore, the higher the gas flow rate, the longer the discharge path is formed in a short time, and the lower the gas flow rate, the shorter the discharge path. Figure 5 (a) represents an example of discharge path 211 when the gas flow rate is high. Figure 5 (b) represents an example of discharge path 212 when the gas flow rate is low.

[0089] When the internal combustion engine 100 operates at a high EGR rate, the probability of flame nucleus growth decreases even if the combustible gas comes into contact with the discharge path, so it is necessary to increase the opportunity for the combustible gas to come into contact with the discharge path. As mentioned above, the discharge path is generated by breaking the insulation of the gas, so if the current required to maintain the discharge path is constant, then the power output needs to be commensurate with the length of the discharge path. Therefore, when the gas flow rate is high, it is preferable to control the energization of the ignition coil 300 by outputting a large amount of power from the ignition coil 300 to the spark plug 200 in a short time, thereby forming... Figure 5 The longer discharge path 211 shown in (a) provides greater contact with the gas in a wider space. On the other hand, when the gas flow rate is low, it is preferable to control the energization of the ignition coil 300 by continuously outputting a small amount of power to the spark plug 200 from the ignition coil 300 over a long period, thereby maintaining the formation of... Figure 5 The shorter discharge path 212 shown in (b) allows for contact with the gas near the electrodes of the spark plug 200 over a longer period of time.

[0090] [Existing ignition coil circuit]

[0091] Next, before describing the embodiments of the present invention, a conventional ignition coil will be described.

[0092] Figure 6 This is a diagram illustrating a conventional circuit 400C including an ignition coil 300C, which serves as a comparative example of the present invention. In the circuit 400C, the ignition coil 300C is configured to include a primary coil 310 wound with a predetermined number of turns and a secondary coil 320 wound with a number of turns greater than that of the primary coil 310.

[0093] One end of the primary coil 310 is connected to the DC power supply 330. Thus, a specified voltage (e.g., 12V) is applied to the primary coil 310.

[0094] The other end of the primary coil 310 is connected to the igniter 340 and grounded via the igniter 340. The igniter 340 uses a transistor or a field-effect transistor (FET).

[0095] The base (B) terminal of the igniter 340 is connected to the ignition control unit 83. The ignition signal SA output from the ignition control unit 83 is input to the base (B) terminal of the igniter 340. When the ignition signal SA is input to the base (B) terminal of the igniter 340, the collector (C) terminal and the emitter (E) terminal of the igniter 340 are energized, and current flows between the collector (C) terminal and the emitter (E) terminal. As a result, the ignition control unit 83 outputs the ignition signal SA to the primary coil 310 of the ignition coil 300 via the igniter 340, and current flows in the primary coil 310 to store electrical energy.

[0096] When the ignition signal SA is stopped from being output from the ignition control unit 83 and the current flowing in the primary coil 310 is cut off, a high voltage corresponding to the coil turns ratio relative to the primary coil 310 is generated in the secondary coil 320.

[0097] The high voltage generated in the secondary coil 320 due to the ignition signal SA is applied to the spark plug 200 (center electrode 210), thereby creating a potential difference between the center electrode 210 and the outer electrode 220 of the spark plug 200. When the potential difference between the center electrode 210 and the outer electrode 220 reaches or exceeds the insulation breakdown voltage Vm of the gas (gas mixture in cylinder 150), the gas components are broken down and a discharge occurs between the center electrode 210 and the outer electrode 220, igniting the fuel (gas mixture).

[0098] In the comparative example, the ignition control unit 83 controls the energization of the ignition coil 300A using the ignition signal SA through the operation of the circuit 400C as described above. This implements ignition control for the spark plug 200.

[0099] [Existing ignition coil discharge control]

[0100] Next, the discharge control of the existing ignition coil will be explained. Figure 7 This is an example of a timing diagram illustrating the relationship between the control signal input to the ignition coil and the output in existing discharge control. Figure 7 The timing diagram is an example of using an existing ignition coil 300C to discharge the spark plug 200 at a high flow rate. Figure 7 The diagram illustrates the relationship between the ignition signal SA output from the ignition control unit 83, the primary current I1 flowing in the primary coil 310 corresponding to the ignition signal SA, the electrical energy E stored in the ignition coil 300C, the secondary current I2 flowing in the secondary coil 320, and the secondary voltage V2 generated in the secondary coil 320. Furthermore, the measurement points for the secondary current I2 and the secondary voltage V2 are shown below. Figure 6As shown, the point is set between spark plug 200 and ignition coil 300C. Additionally, the point for measuring primary current I1 is set between DC power supply 330 and ignition coil 300C.

[0101] When the ignition signal SA becomes HIGH, the igniter 340 energizes the primary coil 310, and the primary current I1 increases. While the primary coil 310 is energized, the electrical energy E in the ignition coil 300C increases over time.

[0102] Subsequently, when the ignition signal SA becomes LOW, the igniter 340 cuts off the power to the primary coil 310. This generates an electromotive force in the secondary coil 320, initiating the supply of electrical energy E from the ignition coil 300C to the spark plug 200. Discharge of the spark plug 200 begins when the insulation between its electrodes breaks down. This discharge of the spark plug 200 accompanied by insulation failure is called capacitive discharge. After the discharge of the spark plug 200 begins, the electrical energy E in the ignition coil 300C decreases over time, sustaining the discharge of the spark plug 200. This discharge of the spark plug 200 without insulation failure is called induced discharge.

[0103] The secondary current I2 increases significantly during capacitor discharge. This secondary current I2 caused by capacitor discharge ends within a short time. When the spark plug 200 begins to discharge and a discharge path is formed between the electrodes, the secondary current I2 decreases sharply and then decreases over time during subsequent induced discharge. The discharge path elongates with the gas flow, so the secondary voltage V2 increases over time. At this time, the magnitude of the secondary current I2 required to maintain the discharge path changes in accordance with the gas flow rate between the electrodes of the spark plug 200.

[0104] When the secondary current I2 is between the minimum value required to maintain the discharge path and the maximum value that no longer allows discharge, the spark plug 200 repeatedly experiences the extinguishing and re-discharge of the discharge path. The range of the secondary current I2 during this repeated extinguishing and re-discharge is referred to as the "intermittent operation range." That is, when the secondary current I2 enters the intermittent operation range, it can no longer maintain the discharge path, and the discharge path is extinguished by the gas flow, thus interrupting the discharge of the spark plug 200. At this time, even if there is no discharge path, because the electrical energy E in the ignition coil 300C remains, a re-discharge (re-ignition) occurs in the spark plug 200 accompanied by capacitor discharge. Figure 7 In the example, the initial discharge is 1 time, the subsequent discharge is 3 times, and the capacitor discharges 4 times.

[0105] When the electrical energy E in the ignition coil 300C decreases, the secondary current I2 also decreases accordingly. When the secondary current I2 falls below its maximum value, at which discharge is no longer possible, the spark plug 200 stops discharging. The range of secondary current I2 at which the spark plug 200 stops discharging is referred to as the "non-dischargeable range".

[0106] In this invention, instead of Figure 6 The ignition coil 300C described herein employs an ignition coil 300 with two primary side coils. Discharge control is performed on this ignition coil 300, thereby suppressing the discharge of the spark plug 200 by reducing the number of capacitor discharges.

[0107] [First Implementation: Ignition Coil Circuit]

[0108] Next, the circuit 400 including the ignition coil 300 according to the first embodiment of the present invention will be described.

[0109] Figure 8 This diagram illustrates a circuit 400 including an ignition coil 300 according to a first embodiment of the present invention. In the circuit 400, the ignition coil 300 is configured to include two primary coils 310 and 360 wound with a predetermined number of turns, and a secondary coil 320 wound with more turns than the primary coils 310 and 360. Here, when the spark plug 200 ignites, power from the primary coil 310 is first supplied to the secondary coil 320, and power from the primary coil 360 is supplied to the secondary coil 320 in superposition with this power. Therefore, the primary coil 310 will be referred to as the "primary primary coil" and the primary coil 360 as the "secondary primary coil" below. Furthermore, the current flowing in the primary primary coil 310 will be referred to as the "primary primary current," and the current flowing in the primary secondary coil 360 will be referred to as the "secondary primary current."

[0110] One end of the primary coil 310 is connected to a DC power supply 330. Thus, a specified voltage (e.g., 12V in the embodiment) is applied to the primary coil 310.

[0111] The other end of the primary coil 310 is connected to the igniter 340 and grounded via the igniter 340. The igniter 340 uses a transistor or a field-effect transistor (FET).

[0112] The base (B) terminal of the igniter 340 is connected to the ignition control unit 83. The ignition signal SA output from the ignition control unit 83 is input to the base (B) terminal of the igniter 340. When the ignition signal SA is input to the base (B) terminal of the igniter 340, the collector (C) terminal and the emitter (E) terminal of the igniter 340 are energized, and current flows between the collector (C) terminal and the emitter (E) terminal. As a result, the ignition control unit 83 outputs the ignition signal SA to the primary coil 310 of the ignition coil 300 via the igniter 340, and the primary current flows in the primary coil 310 to store electrical energy.

[0113] When the ignition signal SA is stopped from being output from the ignition control unit 83 and the primary current flowing in the primary coil 310 is cut off, a high voltage corresponding to the coil turns ratio relative to the primary coil 310 is generated in the secondary coil 320.

[0114] One end of the secondary primary coil 360 and the primary primary coil 310 are connected to the DC power supply 330. Thus, a specified voltage (e.g., 12V in the embodiment) is also applied to the secondary primary coil 360.

[0115] The other end of the secondary primary coil 360 is connected to the igniter 350 and grounded via the igniter 350. The igniter 350 uses a transistor or a field-effect transistor (FET).

[0116] The base (B) terminal of the igniter 350 is connected to the current comparator 380 provided within the ignition control unit 83. The ignition signal SB output from the current comparator 380 is input to the base (B) terminal of the igniter 350. When the ignition signal SB is input to the base (B) terminal of the igniter 350, the collector (C) terminal and emitter (E) terminal of the igniter 350 are energized in a manner corresponding to the voltage change of the ignition signal SB, and a current corresponding to the voltage change of the ignition signal SB flows between the collector (C) terminal and the emitter (E) terminal. Therefore, the ignition signal SB is output from the current comparator 380 to the secondary primary coil 360 of the ignition coil 300 via the igniter 350, and a secondary primary current flows in the secondary primary coil 360, generating electrical power.

[0117] When the output of the ignition signal SB from the current comparator 380 changes and the secondary primary current flowing in the secondary primary coil 360 changes, a high voltage corresponding to the coil turns ratio relative to the secondary primary coil 360 is generated in the secondary coil 320.

[0118] The high voltage generated in the secondary coil 320 due to the ignition signal SA, combined with the high voltage generated in the secondary coil 320 due to the ignition signal SB, is applied to the spark plug 200 (center electrode 210), thereby creating a potential difference between the center electrode 210 and the outer electrode 220 of the spark plug 200. When this potential difference between the center electrode 210 and the outer electrode 220 exceeds the insulation breakdown voltage Vm of the gas (gas mixture in cylinder 150), the gas components are broken down, resulting in a discharge between the center electrode 210 and the outer electrode 220, thus igniting the fuel (gas mixture).

[0119] A current detection unit 370 is provided between the secondary coil 320 and the spark plug 200 to detect the secondary current flowing in the secondary coil 320. The current detection unit 370 sends the detected secondary current value to the current comparison unit 380.

[0120] The ignition control unit 83 sets the current comparison unit 380 with the lower limit of the intermittent operation range (the upper limit of the non-discharge range) and the upper limit of the intermittent operation range as the first setting value and the second setting value to play the role of the threshold.

[0121] The current comparator 380 compares the set second setting value with the secondary current value. After the spark plug 200 begins to discharge, when the secondary current value falls below the second setting value (the upper limit of the intermittent operation range), the current comparator 380 continuously outputs an ignition signal SB to the igniter 350 for a predetermined period. As a result, the current generated by the electrical energy from the secondary primary coil 360 is superimposed on the secondary current flowing in the secondary coil 320.

[0122] Alternatively, the current flowing in the secondary coil 320 due to the primary coil 310 can be calculated, and the output period of the ignition signal SB can be adjusted based on this calculation. Specifically, for example, the secondary primary current flowing in the secondary primary coil 360 due to the ignition signal SB can be detected or calculated, and based on this result, the current flowing in the secondary coil 320 due to the secondary primary coil 360 can be calculated using the turns ratio of the secondary primary coil 360 to the secondary coil 320. In the ignition signal SB output, the secondary current detected by the current detection unit 370 includes the current generated by the primary coil 310 and the superimposed current generated by the secondary primary coil 360. Therefore, by subtracting the calculated value of the superimposed current generated by the secondary primary coil 360 from the detected value of the secondary current, the secondary current based on the power output of the primary coil 310 can be calculated. When the secondary current generated by the primary coil 310 falls below the first set value (the upper limit of the non-discharge range), the current comparison unit 380 stops outputting the ignition signal SB and cuts off the superimposed current generated by the secondary coil 360.

[0123] The ignition control unit 83 and the current comparator 380, using the circuit 400 as described above, control the energization of the ignition coil 300 using ignition signals SA and SB. This enables ignition control for the spark plug 200.

[0124] Alternatively, the current comparator 380 may not be located inside the ignition control unit 83. That is, the ignition control unit 83 and the current comparator 380 may be separate structures. In this case, the current comparator 380 may also be located inside the ignition coil 300. In either case, the current comparator 380 operates in accordance with the control of the ignition control unit 83, so it can be considered that the ignition control unit 83 controls the energization of the ignition coil 300.

[0125] [First Implementation Method: Discharge Control of Ignition Coil]

[0126] Next, the discharge control of the ignition coil according to the first embodiment of the present invention will be described. Figure 9 This is an example of a timing diagram illustrating the relationship between the control signal input to the ignition coil and the output in the discharge control of the first embodiment of the present invention. Figure 9 The timing diagram is an example of how the spark plug 200 is discharged when the ignition coil 300 of this embodiment discharges under high gas flow conditions. Figure 9 The diagram illustrates the relationship between the ignition signal SA output from the ignition control unit 83, the primary current I1 flowing in the primary coil 310 corresponding to the ignition signal SA, the ignition signal SB output from the current comparator 380, the secondary primary current I3 flowing in the secondary coil 360 corresponding to the ignition signal SB, the electrical energy E stored in the ignition coil 300, the secondary current I2 flowing in the secondary coil 320, and the secondary voltage V2 generated in the secondary coil 320. Furthermore, the secondary current I2 and the secondary voltage V2 are as follows... Figure 8 As shown, the current is detected by a current detection unit 370 installed between the spark plug 200 and the ignition coil 300. Furthermore, the primary current I1 and secondary primary current I3 are calculated by a current comparison unit 380 as described above.

[0127] When the ignition signal SA becomes HIGH, the igniter 340 energizes the primary coil 310, causing the primary current I1 to rise. While the primary coil 310 is energized, the electrical energy E within the ignition coil 300 increases over time.

[0128] Subsequently, when the ignition signal SA becomes LOW, the igniter 340 cuts off the power to the primary coil 310. This generates an electromotive force in the secondary coil 320, initiating the supply of electrical energy E from the ignition coil 300 to the spark plug 200. When the insulation between the electrodes of the spark plug 200 breaks, the spark plug 200 begins to discharge (capacitor discharge). After the spark plug 200 begins to discharge, the electrical energy E in the ignition coil 300 decreases over time, maintaining the discharge of the spark plug 200 (inductive discharge).

[0129] The secondary current I2 increases significantly during capacitor discharge. This secondary current I2 caused by capacitor discharge ends within a short time. When the spark plug 200 begins to discharge and a discharge path is formed between the electrodes, the secondary current I2 decreases sharply and then decreases over time during subsequent induced discharge. The discharge path elongates with the gas flow, so the secondary voltage V2 increases over time. At this time, the magnitude of the secondary current I2 required to maintain the discharge path changes in accordance with the gas flow rate between the electrodes of the spark plug 200.

[0130] When the secondary current I2 generated by the primary coil 310 becomes the second set value, i.e. the upper limit of the intermittent operation range, the current comparison unit 380 outputs an ignition signal SB to the igniter 350.

[0131] Hereinafter, the period from when the ignition signal SA becomes LOW until the output ignition signal SB is defined as period P13.

[0132] During the period when the current comparator 380 outputs the ignition signal SB to the igniter 350, the high voltage generated in the secondary coil 320 due to the ignition signal SA is added to the high voltage generated in the secondary coil 320 due to the ignition signal SB. This high voltage is applied to the spark plug 200 (center electrode 210). As a result, the secondary current I2 increases, maintaining the discharge path. The secondary current I2 at this time includes the current flowing in the secondary coil 320 due to the primary coil 310 (hereinafter referred to as the "first induced current") and the current flowing in the secondary coil 320 due to the secondary primary coil 360 (hereinafter referred to as the "second induced current").

[0133] After the ignition signal SA becomes OFF and the spark plug 200 begins discharging, after a predetermined period, or when the first induced current calculated as described above reaches the first set value, i.e., the upper limit of the non-discharge range, the current comparator 380 sets the ignition signal SB to OFF. At this moment, the electrical energy E stored in the ignition coil 300 due to the ignition signal SA has been sufficiently reduced, and the spark plug 200 cannot be discharged using only the output of the ignition coil 300. Therefore, the discharge of the spark plug 200 ends simultaneously with the OFF of the ignition signal SB. As a result, the occurrence of re-discharge (re-ignition) accompanying capacitor discharge in the spark plug 200 is suppressed. Figure 9 In the example, the initial discharge is 1 time, the re-discharge is 1 time, and the capacitor discharges 2 times.

[0134] Figure 10 This is another example of a timing diagram illustrating the relationship between the control signal input to the ignition coil and the output in the discharge control of the first embodiment of the present invention. Figure 10The timing diagram is an example of how the spark plug 200 discharges using the ignition coil 300 of this embodiment at a higher gas flow rate. That is, Figure 10 In the middle, it is shown that... Figure 9 This is an example of a time series plot when the gas flow rate changes at a higher rate.

[0135] Figure 10 In the example, it can be seen that as the gas flow rate changes, the time variation of the secondary voltage V2 increases, thus expanding the intermittent operation range. The threshold value (second setting value) set by the current comparison unit 380 in the ignition control unit 83 increases accordingly. As this threshold increases, the ON period of the ignition signal SB is advanced, thus expanding the pulse width of the ignition signal SB.

[0136] [First Implementation Method: Discharge Control Flow of Ignition Coil]

[0137] Next, the method by which the ignition control unit 83 controls the ignition coil 300 when the above-mentioned discharge control is implemented will be explained. Figure 11 This is an example of a flowchart illustrating the control method of the ignition control unit 83 on the ignition coil 300 according to the first embodiment of the present invention. In this embodiment, when the vehicle's ignition switch is ON and the power supply to the internal combustion engine 100 is connected, the ignition control unit 83... Figure 11 The flowchart begins with the control of the ignition coil 300. Additionally, Figure 11 The flowchart shows the processing of one cycle of the internal combustion engine 100, in which the ignition control unit 83 performs the processing. Figure 11 The process is shown in the flowchart.

[0138] In step S101, the ignition control unit 83 detects the operating conditions of the internal combustion engine 100. Then, based on the detected operating conditions, it calculates a first setting value and a second setting value set for the current comparison unit 380. Specifically, for example, the first setting value and the second setting value determined for each gas flow rate between the electrodes are stored in advance as mapping information. Substituting this mapping information into the gas flow rate between the electrodes calculated based on the detected engine speed and the calculated load, the first setting value and the second setting value corresponding to the current operating state of the internal combustion engine 100 are obtained.

[0139] Figure 12 This is a diagram illustrating an example of mapping information showing the relationship between the gas flow rate between the electrodes and a first set value and a second set value. Figure 12 Figure (a) shows the relationship between the gas flow rate between the electrodes and the second set value. For example... Figure 12 As shown in (a), as the gas flow rate between the electrodes increases, reignition is more likely to occur, so the second setpoint needs to be increased. Figure 12 (b) shows the relationship between the gas flow rate between the electrodes and the first set value. Figure 12 As shown in (b), as the gas flow rate between the electrodes increases, the resistance between the electrodes increases, and the voltage that can be re-discharged increases, so the first set value needs to be increased.

[0140] In the ignition control unit 83, for example, if the ignition is pre-set as follows Figure 12 The relationship between the gas flow rate between the electrodes and the first and second set values ​​shown in (a) and (b) is stored as mapping information, and the processing of step S101 can be performed using this mapping information.

[0141] In step S102, the ignition control unit 83 starts outputting the ignition signal SA at a predetermined time, and then stops outputting the ignition signal SA at a predetermined time. As a result, electrical energy E is supplied from the ignition coil 300 to the spark plug 200, and the discharge of the spark plug 200 begins, with a secondary current I2 flowing in the ignition coil 300.

[0142] In step S103, the ignition control unit 83 uses the current comparison unit 380 to compare the secondary current I2 flowing in the ignition coil 300 with the second set value set in step S101. Furthermore, in this embodiment, the secondary current I2 is detected by the current detection unit 370.

[0143] In step S104, the ignition control unit 83 determines whether the secondary current I2 is below the second set value in the comparison of step S103. If the secondary current I2 is greater than the second set value, it returns to step S103 and continues to compare the secondary current I2 with the second set value. If the secondary current I2 is below the second set value, it proceeds to step S105.

[0144] In step S105, the ignition control unit 83 starts outputting the ignition signal SB using the current comparison unit 380.

[0145] In step S106, the ignition control unit 83 uses the current comparison unit 380 to compare the first induced current flowing in the secondary coil 320 of the ignition coil 300 due to the primary coil 310 with the first set value set in step S101. Furthermore, regarding the first induced current, as described above, the secondary primary current flowing in the secondary coil 360 can be detected or calculated. The second induced current is calculated based on the turns ratio of the secondary primary coil 360 to the secondary coil 320 and subtracted from the secondary current I2, thereby performing the calculation.

[0146] In step S107, the ignition control unit 83 uses the current comparison unit 380 to determine whether the first induced current is below the first set value in the comparison of step S106. If the first induced current is greater than the first set value, the process returns to step S106 and continues to compare the first induced current with the first set value. If the first induced current is below the first set value, the process proceeds to step S108.

[0147] In step S108, the ignition control unit 83 stops outputting the ignition signal SB from the current comparator 380. After stopping the output of the ignition signal SB in step S108, the process ends based on... Figure 11 The flowchart shows the control of the ignition coil 300.

[0148] Alternatively, if the ignition signal SB is continuously output from the current comparator 380 for a predetermined period as described above, steps S106 and S107 can be omitted. In this case, after a predetermined time from when the ignition signal SB is started being output in step S105, step S108 is performed to stop the output of the ignition signal SB.

[0149] According to the first embodiment of the present invention described above, the following effects can be achieved.

[0150] (1) The control device 1 for an internal combustion engine includes an ignition control unit 83 that controls the energization of an ignition coil 300 that provides electrical energy to a spark plug 200, wherein the spark plug 200 ignites fuel by discharging within the cylinder 150 of the internal combustion engine 100. The ignition control unit 83 controls the energization of the ignition coil 300, causing a first electrical energy (electrical energy generated by the primary coil 310) to be released from the ignition coil 300, and a second electrical energy (electrical energy generated by the secondary coil 360) to be released in addition to the first electrical energy. At this time, the energization of the ignition coil 200 is controlled so that the release of the second electrical energy is stopped at the opportune moment when the gas state around the spark plug 200 changes, thereby stopping the discharge of the spark plug 200. Because of this, poor ignition of the gas by the spark plug 200 can be suppressed, and electrode wear of the spark plug 300 in the internal combustion engine 100 can be suppressed.

[0151] (2) The ignition coil 300 has primary coils 310 and 360 disposed on the primary side and a secondary coil 320 disposed on the secondary side. The ignition control unit 83 controls the energization of the ignition coil 300, causing a first induced current to flow in the secondary coil 320 based on the primary current flowing in the primary coils 310 and 360, and when the first induced current falls below a predetermined first set value (step S107: Yes), a second induced current flowing in the secondary coil 320 superimposed on the first induced current is cut off. Because of this, the second induced current flowing superimposed on the first induced current can be cut off at an appropriate time.

[0152] (3) The first setting value is set based on the current value (secondary current I2) of the secondary coil 320 in the non-dischargeable region where the spark plug 200 cannot discharge. Because of this, the timing of cutting off the second induced current can be determined in a way that reliably suppresses the occurrence of re-ignition in the spark plug 200.

[0153] (4) The ignition control unit 83 controls the energization of the ignition coil 300 so that when the first induced current becomes less than or equal to a predetermined second set value (step S104: Yes), the second induced current begins to flow. Because of this, it is possible to appropriately determine the timing at which the second induced current begins to flow in conjunction with the first induced current.

[0154] (5) The second setting value is set based on the current value (secondary current I2) of the secondary coil 320 during the intermittent operation period when the spark plug 200 restarts due to the interruption of discharge. Because of this, the timing of starting the flow of the second induced current can be determined in a way that reliably suppresses the occurrence of restart in the spark plug 200.

[0155] (6) The primary coils 310 and 360 have a main primary coil 310 and a secondary primary coil 360. The ignition control unit 83 controls the energization of the ignition coil 300 so that a first induced current flows in the secondary coil 320 by cutting off the energization of the main primary coil 310. In addition, the energization of the ignition coil 300 is controlled so that a second induced current flows in the secondary coil 320 by energizing the secondary primary coil 360. Because of this, the first induced current can flow using the main primary coil 310, and the second induced current can flow using the secondary primary coil 360 in combination with the first induced current.

[0156] (7) When the first induced current falls below the first set value (step S107: Yes), the ignition control unit 83 cuts off the energization of the secondary primary coil 360. Because of this, the second induced current generated by the secondary primary coil 360, which flows in conjunction with the first induced current, can be cut off at the appropriate time.

[0157] [Second Implementation: Ignition Coil Circuit]

[0158] Next, the circuit 400A including the ignition coil 300 according to the second embodiment of the present invention will be described.

[0159] Figure 13 This is a diagram illustrating a circuit 400A including an ignition coil 300 according to a second embodiment of the present invention. In this embodiment, the ignition coil 300 has the same characteristics as described in the first embodiment. Figure 8 The same structure. That is, the ignition coil 300 of this embodiment also includes two primary coils 310 and 360 (main primary coil 310 and auxiliary primary coil 360) wound with a specified number of turns respectively, and a secondary coil 320 wound with more turns than the primary coils 310 and 360.

[0160] In this embodiment, circuit 400A differs from circuit 400 described in the first embodiment in that the current detection unit 370 and the current comparison unit 380 are omitted. Furthermore, in this embodiment, the base (B) terminal of the igniter 350 is connected to the ignition control unit 83. The ignition control unit 83 outputs an ignition signal SB to the base (B) terminal of the igniter 350. Thus, similar to the first embodiment, a secondary primary current flows in the secondary primary coil 360, generating electrical power.

[0161] In this embodiment, the ON and OFF periods of the ignition signal SB are set by the ignition control unit 83 to be predetermined periods that start from the OFF period of the ignition signal SA and correspond to the operating state of the internal combustion engine 100.

[0162] The ignition control unit 83, using the circuit 400A as described above, controls the energization of the ignition coil 300 via ignition SA and SB. This enables ignition control for the spark plug 200.

[0163] [Second Implementation Method: Discharge Control Flow of Ignition Coil]

[0164] Next, the control method of the ignition control unit 83 on the ignition coil 300 during the discharge control of the ignition coil in the second embodiment of the present invention will be described. Figure 14 This is an example of a flowchart illustrating the control method of the ignition control unit 83 on the ignition coil 300 according to the second embodiment of the present invention. In this embodiment, when the vehicle's ignition switch is ON and the power supply to the internal combustion engine 100 is connected, the ignition control unit 83... Figure 14 The flowchart begins with the control of the ignition coil 300. Additionally, Figure 14 The flowchart shows the processing of one cycle of the internal combustion engine 100, in which the ignition control unit 83 performs the processing. Figure 14 The process is shown in the flowchart.

[0165] In step S201, the ignition control unit 83 detects the operating conditions of the internal combustion engine 100.

[0166] In step S202, the ignition control unit 83 calculates the gas flow rate between the electrodes based on the operating conditions detected in step S201. Specifically, by substituting the engine speed and calculated load detected in step S201 into the mapping of the gas flow rate determined in advance for each operating condition, the value of the gas flow rate between the electrodes is obtained.

[0167] In step S203, the ignition control unit 83 calculates the pulse width of the ignition signal SB. Specifically, for example, the pulse width of the ignition signal SB, which is determined by each gas flow rate between the electrodes, is stored in advance as mapping information. This mapping information is then substituted into the gas flow rate calculated in step S202 to obtain the pulse width of the ignition signal SB corresponding to the current operating state of the internal combustion engine 100.

[0168] Figure 15 This is an example diagram illustrating the mapping information showing the relationship between the gas flow rate between the electrodes and the pulse width of the ignition signal SB. When the gas flow rate between the electrodes of spark plug 200 increases, the time-dependent change in the secondary voltage V2 increases, thus widening the intermittent operation range. Therefore, it is necessary to... Figure 15 As shown, this causes the pulse width of the ignition signal SB to increase.

[0169] In the ignition control unit 83, for example, such as Figure 15 The relationship between the gas flow rate between the electrodes and the pulse width of the ignition signal SB is stored in advance as mapping information, which can be used to implement the processing in step S203.

[0170] return Figure 14 As explained, in step S204, the ignition control unit 83 calculates the period P13 from when the ignition signal SA becomes LOW until the ignition signal SB is output. Specifically, for example, the value of the period P13 determined for each gas flow rate between the electrodes is stored in advance as mapping information. This mapping information is then substituted into the gas flow rate calculated in step S202 to obtain the period P13 corresponding to the current operating state of the internal combustion engine 100.

[0171] Figure 16 This is an example diagram showing the relationship between the gas flow rate between the electrodes and the period P13 from the ignition signal SA becoming LOW until the output ignition signal SB. When the gas flow rate between the electrodes of spark plug 200 increases, the time-dependent change in the secondary voltage V2 increases, thus widening the intermittent operation range. Therefore, it is necessary to... Figure 15 As shown, the period P13 is shortened accordingly, causing the ON axis of the ignition signal SB to be advanced.

[0172] In the ignition control unit 83, for example, such as Figure 16 The relationship between the gas flow rate between the electrodes and the period P13 until the ignition signal SB is output is stored in advance as mapping information, and the processing of step S204 can be performed using the mapping information.

[0173] return Figure 14As explained, in step S205, the ignition control unit 83 sets the pulse width of the ignition signal SB calculated in step S203 and the period P13 until the ignition signal SB is output, calculated in step S204. Specifically, for example, these calculated values ​​are recorded in a storage area (not shown) provided in the ignition control unit 83, and these calculated values ​​are reflected in the processing after step S206.

[0174] In step S206, the ignition control unit 83 starts outputting the ignition signal SA at a predetermined time, and then stops outputting the ignition signal SA at a predetermined time. As a result, electrical energy E is supplied from the ignition coil 300 to the spark plug 200, and the discharge of the spark plug 200 begins, with a secondary current I2 flowing in the ignition coil 300.

[0175] In step S207, the ignition control unit 83 determines whether the elapsed time since the ignition signal SA was stopped in step S206 has reached the period P13 set in step S205. If the period P13 has not elapsed since the ignition signal SA was stopped, the process remains in step S207; if the period P13 has elapsed, the process proceeds to step S208.

[0176] In step S208, the ignition control unit 83 outputs an ignition signal SB according to the pulse width set in step S205. That is, after starting to output the ignition signal SB, the output of the ignition signal SB stops after the set pulse width period. After stopping the output of the ignition signal SB in step S208, the process based on... Figure 14 The flowchart shows the control of the ignition coil 300.

[0177] According to the second embodiment of the present invention described above, the ignition control unit 83 controls the energization of the ignition coil 300, so that a first electrical energy (electrical energy generated by the main primary coil 310) is released from the ignition coil 300 and a second electrical energy (electrical energy generated by the auxiliary primary coil 360) is released in superposition with the first electrical energy. At this time, the energization of the ignition coil 300 is controlled so that the release of the second electrical energy is stopped at the timing when the gas state around the spark plug 200 changes, thereby stopping the discharge of the spark plug 200. Because of this, as in the first embodiment, it is possible to suppress poor ignition of the gas by the spark plug 200, and at the same time suppress electrode wear of the spark plug in the internal combustion engine 100.

[0178] [Third Implementation Method]

[0179] Next, a third embodiment of the present invention will be described. In this embodiment, a method for confirming the operation of the ignition control unit 83 will be described.

[0180] Figure 17This diagram illustrates a circuit 400B including an ignition coil 300 according to a third embodiment of the present invention. In this embodiment, the circuit 400B differs from the circuit 400 described in the first embodiment in that a noise-prevention resistor 390 is connected between the ignition coil 300 and the spark plug 200. Furthermore, the resistor 390 can be connected in any location as long as it is connected in series with the spark plug 200.

[0181] In this embodiment, the ignition control unit 83 performs the same operation as described in the first embodiment. That is, the ignition control unit 83 has a current comparator 380, outputs an ignition signal SA, and outputs an ignition signal SB using the current comparator 380. Thus, the energization of the ignition coil 300 is controlled such that a first induced current flows in the secondary coil 320 based on the primary current flowing in the primary coil 310, and when the first induced current falls below a second set value corresponding to the upper limit of the intermittent operation range, a second induced current flows in the secondary coil 320 based on the secondary primary current flowing in the secondary coil 310, superimposed on the first induced current. Furthermore, the energization of the ignition coil 300 is controlled such that when the first induced current falls below a first set value corresponding to the upper limit of the non-discharge range, the second induced current is cut off.

[0182] In this embodiment, the operation of the ignition control unit 83 can be confirmed as follows. First, the resistor 390 is set to a predetermined resistance value, causing the internal combustion engine 100 to run. Ignition signals SA and SB are output from the ignition control unit 83 to discharge the spark plug 200. Then, the change in the secondary current I2 over time is measured.

[0183] Next, the resistance value of resistor 390 is set to a different value than described above, thereby changing the rate at which the secondary current I2 decreases. In this state, the internal combustion engine 100 is put into operation, and ignition signals SA and SB are output from the ignition control unit 83 to discharge the spark plug 200. Then, the change in the secondary current I2 over time is measured.

[0184] As explained above, the changes in the secondary current I2 over time, measured at different resistance values, were compared. If, even with changes in the resistance value of resistor 390, the current component of the secondary current I2 flowing due to the ignition signal SB—that is, the current value of the second induced current flowing in the secondary coil 320 superimposed on the first induced current—remains constant when it is cut off, then it can be confirmed that the ignition control unit 83 determines the timing for stopping the output of the ignition signal SB based on the aforementioned first setting value. In other words, it is known that the ignition control unit 83, in accordance with the change in the resistance value of resistor 390, changes the timing for cutting off the second induced current to keep the current in the spark plug 200 constant when the second induced current is cut off. Therefore, it can be confirmed that the ignition control unit 83 has performed the required operation.

[0185] Furthermore, using the same method, if the current value of the second induced current in the secondary current I2, which is superimposed on the first induced current due to the ignition signal SB, and which begins to flow in the secondary coil 320, remains constant even if the resistance value of resistor 390 changes, then it can be confirmed that the ignition control unit 83 determines the timing of starting to output the ignition signal SB based on the aforementioned second setting value. That is, it can be seen that the ignition control unit 83, in accordance with the change in the resistance value of resistor 390, changes the timing of the second induced current's initiation to maintain a constant current in the spark plug 200 when the second induced current begins to flow. Therefore, it can be confirmed that the ignition control unit 83 has performed the required operation.

[0186] In this embodiment, the operation of the ignition control unit 83 can be confirmed using the method described above.

[0187] Furthermore, in the third embodiment described above, an example was given of confirming the operation of the ignition control unit 83 described in the first embodiment by using circuit 400B, which adds a resistor 390 to the circuit 400 described in the first embodiment. However, the operation of the ignition control unit 83 can also be confirmed using the same method in the second embodiment. That is, by adding a resistor 390 to the circuit 400A described in the second embodiment and using the method described above, it can be confirmed that the ignition control unit 83 has performed the required operation.

[0188] According to the third embodiment of the present invention described above, a resistor 390 with a predetermined resistance value is connected between the secondary coil 320 and the spark plug 200. The timing of cutting off the second induced current is changed accordingly to maintain a constant current in the spark plug 200 when the second induced current is cut off, in order to keep the current in the spark plug 200 constant when the second induced current begins to flow, in accordance with the change in the resistance value of the resistor 390. Therefore, it is possible to confirm that the ignition control unit 83 has performed the required operation.

[0189] In addition, in the embodiments described above, Figure 3 The functional structures of the control device 1 described herein can be implemented using software executed by the MPU50 as described above, or they can be implemented using hardware such as an FPGA (Field-Programmable Gate Array). Alternatively, they can coexist and be used simultaneously.

[0190] The embodiments and variations described above are merely examples, and the present invention is not limited to these descriptions as long as they do not impair the characteristics of the invention. Furthermore, while various embodiments and variations have been described above, the present invention is not limited to these descriptions. Other methods conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0191] Explanation of reference numerals in the attached figures

[0192] 1: Control device; 10: Analog input unit; 20: Digital input unit; 30: A / D converter; 40: RAM; 50: MPU; 60: ROM; 70: I / O port; 80: Output circuit; 81: Overall control unit; 82: Fuel injection control unit; 83: Ignition control unit; 84: Cylinder detection unit; 85: Angle information generation unit; 86: Speed ​​information generation unit; 87: Intake volume meter; 88: Load information generation unit; 89: Water temperature meter; 100: Internal combustion engine; 110: Air filter; 111: Intake pipe; 112: Intake manifold; 113: Throttle valve; 113a: Throttle opening sensor; 114: Flow sensor; 115: Intake air temperature sensor; 120: Ring gear; 121: Crank angle sensor; 122: Water temperature sensor; 123: Crankshaft; 125: Accelerator pedal; 126: Acceleration position sensor, 130: fuel container, 131: fuel pump, 132: pressure regulator, 133: fuel pipe, 134: fuel injection valve, 140: combustion pressure sensor, 150: cylinder, 151: intake valve, 152: exhaust valve, 160: exhaust manifold, 161: three-way catalytic converter, 162: upstream air-fuel ratio sensor, 163: downstream air-fuel ratio sensor, 170: piston, 200: spark plug, 210: center electrode, 220: outer electrode, 230: insulator, 300, 300C: ignition coil, 310: primary coil, 320: secondary coil, 330: DC power supply, 340, 350: igniter, 360: secondary coil, 370: current detection unit, 380: current comparator, 390: resistor, 400, 400A, 400B, 400C: circuit.

Claims

1. A control device for an internal combustion engine, characterized in that: An ignition control unit has an ignition control unit that controls the energization of an ignition coil to provide a first electrical energy and a second electrical energy superimposed on the first electrical energy to the spark plugs in each combustion cycle of an internal combustion engine, wherein the spark plugs discharge within the cylinders of the internal combustion engine to ignite fuel. The ignition coil has a primary coil disposed on the primary side and a secondary coil disposed on the secondary side. The primary coil has a main primary coil and a secondary primary coil. The ignition control unit The period from the start of the release of the first electrical energy from the start of the release of the second electrical energy is set based on the gas flow rate around the spark plug before ignition in the combustion cycle. The energization of the ignition coil is controlled such that the first electrical energy is released from the spark plug by cutting off the energization of the main primary coil, and after the period has elapsed, the second electrical energy is released from the ignition coil in combination with the first electrical energy by energizing the secondary primary coil. Furthermore, the energization of the ignition coil is controlled such that when the first electrical energy decreases to the point where the discharge of the spark plug based on the first electrical energy becomes impossible, the release of the second electrical energy from the ignition coil is stopped by cutting off the energization of the secondary primary coil.

2. The control device for an internal combustion engine as described in claim 1, characterized in that: The ignition control unit stores the value of the period, which is predetermined according to each gas flow rate between the electrodes of the spark plug, as first mapping information. The ignition control unit calculates the gas flow rate between the electrodes before ignition in the combustion cycle, and calculates the period based on the calculated gas flow rate and the first mapping information.

3. The control device for an internal combustion engine as described in claim 2, characterized in that: The ignition control unit is capable of outputting a first ignition signal and a second ignition signal. The first ignition signal is used to control the energization of the ignition coil to accumulate and release the first electrical energy, and the second ignition signal is used to control the energization of the ignition coil to release the second electrical energy. The ignition control unit stores the pulse width value of the second ignition signal, which is predetermined according to each gas flow rate, as second mapping information. The ignition control unit The pulse width of the second ignition signal is calculated based on the calculated gas flow rate before ignition in the combustion cycle and the second mapping information. By outputting the first ignition signal and then stopping the output of the first ignition signal at a predetermined time, the power of the ignition coil is controlled to release the first electrical energy from the ignition coil. The second ignition signal is output with the calculated pulse width when the elapsed time from the termination of the first ignition signal output reaches the specified period, thereby controlling the power of the ignition coil to release the second electrical energy from the ignition coil.

Images