JP2015090140A - Device for determining combustion state of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine a combustion state from an ion current even when an internal combustion engine has lean combustion with lean fuel or combustion with a large quantity of EGR.SOLUTION: A second ignition coil 10b performs electric discharge from a second ignition plug 70b into a cylinder 110 at a closer position to on an advance side than the execution of fuel injection from an injector 150, and an ion current between the electrodes of the second ignition plug 70b is detected, which is generated by combustion in which electric discharge of a first ignition plug 70a provided on an intake side of the cylinder 110 propagates from combustion near the first ignition plug 70a to an exhaust side of the cylinder 110. Secondary coils 30a, 30b of the first and second ignition coils 10a, 10b are connected to ion current detection means 80 via switch elements 90a, 90b and are brought in conduction with the ion current detection means 80 or a ground through switching of contacts.

Description

  The present invention relates to a combustion state determination device for determining a combustion state using an ion current generated after combustion of an internal combustion engine in an internal combustion engine used for a power source of an automobile or the like.

  Conventionally, due to environmental problems and fossil fuel depletion problems, an internal combustion engine has performed lean combustion with a lean fuel with a high air-fuel ratio of the air-fuel mixture supplied into the cylinder and combustion with a large amount of EGR. However, lean combustion tends to cause misfire due to the thin fuel, and it is necessary to always grasp the combustion state and control to improve the combustion state. As a method for determining this combustion state, the electrode of the spark plug is determined by the combustion of the internal combustion engine. For example, Japanese Patent Application Laid-Open No. 2008-280887 (hereinafter “Patent Document 1”) is known.

  In Patent Document 1, ion current detection means for continuously detecting the value of an ion current flowing in a combustion chamber by the action of ions generated in the combustion process of an internal combustion engine, and the ion current detected by the ion current detection means Based on the value, the first peak generation time at which the ion current value peaks first after the start of combustion, and the second peak generation time at which the ion current value peaks after the first peak generation time Whether or not the first peak generation time and / or the second peak generation time detected by the peak generation time detection means and the ion current peak generation time detection means depends on the combustion characteristics of the internal combustion engine. A peak generation time determination means for determining; the first peak generation time detected by the ion current peak generation time detection means; Combustion state determination means for determining the combustion state of the internal combustion engine based on the peak generation time, ignition set in advance according to the determination result of the peak generation time determination means and the determination result of the combustion state determination means A control device for an internal combustion engine has been proposed that includes correction means for correcting at least one set value of the timing, the fuel injection timing, and the fuel injection amount.

JP 2008-280887 A

  However, the above-described conventional control device for an internal combustion engine has the following problems. That is, in Patent Document 1, when it is determined that the peak position of the ion current is detected by the influence other than the combustion characteristics by determining the appropriateness of the first peak generation time and the second peak generation time of the ion current, Excluded from the calculation of the correction value and corrects the ignition timing, fuel injection timing, and fuel injection amount according to the determined combustion state of the internal combustion engine, but when the internal combustion engine is lean burning with lean fuel Since the ion current generated by combustion is also minute, it is difficult to accurately detect the first and second peak positions. Further, since the ionic current is easily affected by noise from an electronic device mounted on the automobile, when the first and second peak positions are detected from the ionic current superimposed with noise, the ignition timing, the fuel injection timing, and the fuel injection amount are detected. There arises a problem in that the correction is not performed correctly.

  The present invention has been made in view of the above problems, and a combustion state determination device for an internal combustion engine that can accurately determine a combustion state from an ionic current even when the internal combustion engine is lean combustion with lean fuel or combustion with a large amount of EGR. The goal is to provide

  In order to solve the above problems, the present invention has the following configuration. That is, two ignition plugs arranged at a certain distance in a single cylinder of the internal combustion engine, two ignition coils individually provided in the ignition plug, and an air-fuel mixture in the cylinder of the internal combustion engine The combustion state of the internal combustion engine comprising: an ion current detection means for detecting an ion current generated between the electrodes of the spark plug as a result of combustion, and a combustion state determination means for determining the combustion state of the internal combustion engine from the detected ion current In the determination device, the second spark plug performs an ignition operation during the exhaust stroke of the internal combustion engine or the intake stroke of the direct injection engine, and the first spark plug performs an ignition operation during the compression stroke of the internal combustion engine. The ion current detecting means detects an ion current generated between the electrodes of the second spark plug, and the combustion state determining means is configured to detect a state before the discharge of the first spark plug. Second spark plug and the combustion state determination device for an internal combustion engine which is characterized in that the flame propagation determined from time to detect the ion current (claim 1).

  In the above invention, the two spark plugs perform an ignition operation during a compression stroke, and the ion current detection means detects an ion current generated between the electrodes of the two spark plugs to determine the combustion state. The means may be configured to perform combustion determination of at least one of combustion state deterioration including misfire in the cylinder, pre-ignition, and knocking (Claim 2). Further, the ion current detecting means is provided for the two ignition coils arranged in the single cylinder, and the secondary coil of the two ignition coils detects the ion current via a switching element. It is good also as a structure connected with a means (Claim 3). Furthermore, the internal combustion engine may be either a diesel engine or a homogeneous premixed compression ignition engine.

  According to a fourth aspect of the present invention, the two spark plugs perform an ignition operation before fuel injection to the cylinder of the internal combustion engine, and the ion current detecting means is an ion current generated between the electrodes of the two spark plugs. The combustion state determination means may perform a combustion determination of at least any one of deterioration of combustion state including misfire in the cylinder, pre-ignition, and knocking (Claim 5).

  According to the above configuration, the second spark plug performs the ignition operation during the exhaust stroke of the internal combustion engine or the intake stroke of the direct injection engine, and the first spark plug performs the ignition operation during the compression stroke of the internal combustion engine. The ion current detecting means detects the ion current generated between the electrodes of the second spark plug, and the combustion state determining means detects the ion current from the discharge of the first spark plug by the second spark plug. Combustion state determination device for an internal combustion engine that determines accurate flame propagation even if the internal combustion engine is a minute ion current generated by lean combustion by lean fuel or combustion by a large amount of EGR by performing flame propagation determination from the time until Therefore, it is possible to prevent the power loss of the internal combustion engine due to the fact that the flame propagation in the cylinder is not accurately performed (claim 1).

  In addition, the two spark plugs perform an ignition operation during the compression stroke, the ion current detection means detects the ion current generated between the electrodes of the two spark plugs, and the combustion state determination means detects the misfire in the cylinder. The combustion speed is improved by the discharge from the two spark plugs by performing at least one of the combustion determination including the deterioration of the combustion state, the premature ignition, and the knocking, and the internal combustion engine performs lean combustion with lean fuel and a large amount of EGR. The combustion state can be accurately determined even with a minute ion current generated by the combustion due to the above (claim 2). Furthermore, one ionic current detection means is provided for two ignition coils arranged in a single cylinder, and secondary coils of the two ignition coils are connected to the ionic current detection means via a switch element. Thus, flame propagation from the discharge of the first spark plug to the detection of the ion current by the second spark plug is determined from the minute ion current without changing the ion current detection means provided for one cylinder. It is possible to switch between control and control for determining the combustion state from the ionic current synthesized by the two spark plugs.

  The internal combustion engine is either a diesel engine or a uniform premixed compression ignition type engine, so that the combustion state is determined from the ionic current even in a diesel engine or a uniform premixed compression ignition type engine with a high air-fuel ratio. At the same time, assist ignition for self-ignition failure of the diesel engine and spark ignition combustion (SI combustion) of the homogeneous premixed compression ignition (HCCI) engine can be performed.

  Further, the two spark plugs perform an ignition operation before fuel injection to the cylinder of the internal combustion engine, the ion current detection means detects an ion current generated between the electrodes of the two spark plugs, and the combustion state determination means includes: Even if a minute ion current due to combustion of a diesel engine or an HCCI engine with a high air-fuel ratio is determined by performing at least one of combustion determination including combustion deterioration, premature ignition, and knocking including misfire in the cylinder Can be accurately determined (Claim 5).

It is a figure which shows the equivalent circuit of the combustion state determination apparatus of the internal combustion engine which is 1st Example of this invention. 1 is a diagram showing a schematic diagram of a uniform premixed compression ignition (HCCI) engine as Example 1. FIG. It is a figure which shows the combustion stroke of the HCCI engine made into Example 1. FIG. It is a figure which shows the driving | operation area | region of the HCCI engine made into Example 1. FIG. It is a figure which shows the schematic of the intake stroke-> compression stroke-> combustion stroke at the time of flame propagation determination by the spark ignition (SI) combustion of the HCCI engine made into Example 1. FIG. It is a figure which shows the equivalent circuit of the combustion state determination apparatus at the time of flame propagation determination by SI combustion as Example 1. FIG. The time chart of the ignition signal of the combustion state determination apparatus at the time of flame propagation determination by SI combustion made into Example 1, a primary current, a secondary current, and an ion current is shown. It is a figure which shows the schematic of the intake stroke-> compression stroke-> combustion stroke at the time of the combustion determination by SI combustion of the HCCI engine made into Example 1. FIG. It is a figure which shows the equivalent circuit of the combustion state determination apparatus at the time of the combustion determination by SI combustion made into Example 1. FIG. The time chart of the ignition signal of the combustion state determination apparatus at the time of the combustion determination by SI combustion made into Example 1, a primary current, a secondary current, and an ion current is shown. It is a figure which shows the schematic of the intake stroke-> compression stroke-> combustion stroke at the time of the combustion determination by the HCCI combustion of the HCCI engine made into Example 1. FIG. The time chart of the ignition signal of the combustion state determination apparatus at the time of HCCI combustion made into Example 1 and a primary current, a secondary current, and an ion current is shown.

  An example showing an embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a diagram showing an equivalent circuit of a combustion state determination device for an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a diagram showing a schematic diagram of a homogeneous premixed compression ignition (HCCI) engine, and FIG. FIG. 3 is a diagram showing the combustion stroke of the engine, FIG. 4 is a diagram showing the operation region of the HCCI engine, and an intake stroke → compression stroke → combustion stroke at the time of flame propagation determination by spark ignition (SI) combustion of the HCCI engine FIG. 5 is a diagram showing a diagram, FIG. 6 is a diagram showing an equivalent circuit of a combustion state determination device at the time of flame propagation determination by SI combustion, FIG. 6 is an ignition signal of the combustion state determination device at the time of flame propagation determination by SI combustion, FIG. 7 is a time chart of current, secondary current and ion current, FIG. 8 is a schematic diagram showing intake stroke → compression stroke → combustion stroke at the time of combustion judgment by SI combustion of the HCCI engine, and FIG. 8 is a combustion judgment by SI combustion. Burning state of time FIG. 9 is a diagram showing an equivalent circuit of the determination device, FIG. 10 is a time chart of the ignition signal, primary current, secondary current, and ion current of the combustion state determination device at the time of combustion determination by SI combustion, and FIG. 10 shows the HCCI of the HCCI engine. FIG. 11 is a diagram showing a schematic diagram of the intake stroke → compression stroke → combustion stroke at the time of combustion determination by combustion. FIG. 11 is a time chart of the ignition signal, primary current, secondary current, and ion current of the combustion state determination device at the time of HCCI combustion. Are shown in FIG.

  In FIG. 1, the combustion state determination apparatus for an internal combustion engine includes a first ignition coil 10a and a second ignition coil 10b. The first ignition coil 10a includes a primary coil 20a, a secondary coil 30a, and an iron core 40a. The second ignition coil 10b is composed of a primary coil 20b, a secondary coil 30b, an iron core 40b, and a second igniter 50b. The first ignition coil 10a and the second ignition coil 10b are supplied with voltage from the same power source 60, and are boosted to the same output and supplied to the ignition plugs 70a and 70b. Further, the first ignition coil 10a and the second ignition coil 10b are connected to the ion current detection means 80, and the ion current detection means 80 includes a Zener diode 82, a diode 84, a capacitor 85, resistors 86a and 86b, And an operational amplifier 88.

  The first ignition coil 10a has a low voltage side of the primary coil 20a connected to the power source 60 and a high voltage side connected to the collector side of the first igniter 50a. Further, the low voltage side of the second ignition coil 30a is connected to the ion current detecting means 80, and the high voltage side is connected to the first spark plug 70a.

  The second ignition coil 10b has a low voltage side of the primary coil 20b connected to the power source 60 and a high voltage side connected to the collector side of the second igniter 50b. Further, the low voltage side of the second ignition coil 30b is connected to the ion current detecting means 80, and the high voltage side is connected to the second spark plug 70b.

  The first and second igniters 50a and 50b have an emitter side connected to the ground and a gate side connected to an ignition control means provided in an ECU (Engine Control Unit) for controlling the engine of the automobile. The primary coils 20a and 20b are energized by turning ON / OFF the ignition signal from the ECU as a gate current. Further, the ion current detecting means 80 has the cathode terminal of the Zener diode 82 connected to the low voltage side of the secondary coils 30a and 30b of the first and second ignition coils 10a and 10b, and the anode terminal thereof connected to the anode terminal. The anode terminal of the diode 84 is connected.

  In addition, the ion current detecting means 80 has the cathode terminal of the diode 84 connected to the ground, and the capacitor 85 for generating a bias power supply connected to the Zener diode 82 in parallel. Furthermore, one end of the resistor 86a is connected to the parallel circuit of the Zener diode 82 and the capacitor 85, and the other end is connected to the inverting input terminal of the operational amplifier 88.

  The operational amplifier 88 has a non-inverting input terminal connected to the ground and an output terminal connected to combustion state determination means provided in the ECU. Further, the operational amplifier 88 has the detection resistor 86b connected in parallel to the inverting input terminal and the output terminal.

  The secondary coils 30a and 30b of the first and second ignition coils 10a and 10b are connected to the Zener diode 82 via switch elements 90a and 90b, and the switch elements 90a and 90b are switched. The energization to the Zener diode 82 or the ground is changed. Further, the switch elements 90a and 90b are constituted by relays, and the ECU switches the contact by the ECU so as to conduct with the Zener diode 82 or the ground.

  In FIG. 2, the internal combustion engine is a four-cylinder uniform premixed compression ignition type (hereinafter “HCCI”) engine, and is composed of four cylinders 100 including an engine block and an engine head. The block is fixed by a plurality of head bolts. The engine block is opened by a substantially cylindrical cylinder 110 penetrating in the vertical direction, the upper end of the opening is covered with the engine head, and a recess is formed from the lower end of the opening. Further, the cylinder 110 is sealed with a piston 120 fitted in the recess, and the piston 120 is defined as a bottom surface and the engine head is defined as an upper surface.

  The compression ratio of the cylinder 110 is preferably set in the range of 11 to 13 so as to be optimal for compressing and pre-igniting the premixed gas in the cylinder 110. Furthermore, the upper end of the cylinder 110 is shaped like a roof by two inclined surfaces, and the two inclined surfaces gradually move from the center of the upper end of the cylinder 110 toward the left and right sides. It extends to approach the mating surface with the inner wall.

  Further, an intake port 130 is connected to the inclined surface at the upper end of the cylinder 110 shown on the left side of the drawing, and an exhaust port 140 is connected to the inclined surface at the upper end of the cylinder 110 shown on the right side of the drawing. Further, the internal combustion engine is a four-valve type in which two intake and exhaust ports 130 and 140 are provided for one cylinder 110, and the intake and exhaust ports 130 and 140 and the cylinder 110 are provided. The connection portion is provided with intake and exhaust valves 132 and 142.

  The intake and exhaust valves 132 and 142 are each provided with a coil spring, and the coil spring is pressed in the direction in which the intake and exhaust valves 132 and 142 are closed. The intake and exhaust valves 132 and 142 are pushed down in the opening direction by the intake and exhaust cams 134 and 144 that rotate in conjunction with each other. Further, the intake and exhaust cams 134 and 144 are rotated in synchronization with the intake and exhaust camshafts 136 and 146, respectively, so that the intake and exhaust valves 132 and 142 are opened and closed at predetermined timings, respectively.

  Each of the intake and exhaust camshafts 136 and 146 is provided with a variable valve timing mechanism that continuously changes the rotation phase with respect to the crankshaft 124 that rotates the piston 120 in a predetermined angular range. The opening and closing timings of the intake and exhaust valves 132 and 142 are independently changed by the variable valve timing mechanism. Furthermore, although the variable valve timing mechanism is of the hydraulic continuous phase change system, an electromagnetic operation type of continuous phase change system may be used.

  Further, by operating the variable valve timing mechanisms of the intake and exhaust camshafts 136 and 146 to the retard side and the advance side, respectively, the overlap of the intake and exhaust valves 132 and 142 can be eliminated. Thus, a large amount of EGR (burned gas) can be retained in the cylinder 110. Furthermore, if the period from when the exhaust valve 142 is closed to when the intake valve 132 is opened becomes shorter, the amount of EGR gas decreases, and the period from when the exhaust valve 142 is closed to when the intake valve 132 is opened is longer. If so, the amount of internal EGR gas increases accordingly.

  Further, the first spark plug 70a is disposed at the upper end in the cylinder 110, and the second spark plug 70b is disposed on the exhaust valve 142 side of the cylinder 110. The first and second spark plugs 70a and 70b perform spark ignition (hereinafter referred to as “SI”) combustion in which the air-fuel mixture supplied into the cylinder 110 is ignited and burned at a predetermined timing at the end of the compression stroke. It is. Further, the internal combustion engine includes an injector 150 on the intake port 130 side of the cylinder 110 as a direct injection engine that directly injects gasoline into the cylinder 110.

  Further, the ECU is provided with information from a pressure sensor that detects the pressure in the cylinder 110 and a knock sensor that detects knocking from abnormal vibration of the internal combustion engine, and is provided in the intake port 130. The fuel injection amount is controlled by controlling the opening / closing of the electric throttle valve and the opening / closing time of the injector 150, thereby controlling the air-fuel ratio of the air-fuel mixture in the cylinder 110. Further, the ECU controls the overlap period of the intake and exhaust valves 132 and 142 by changing the opening and closing timing of the intake and exhaust valves 132 and 142 by hydraulic control of the variable valve timing mechanism.

  In FIG. 3, the cylinder 100 performs an intake stroke → compression stroke → combustion stroke → exhaust stroke while the crankshaft 124 makes two rotations (720 °), with an interval of 180 ° for every four cylinders. Is called. In the combustion stroke of the cylinder 100, combustion is performed in the order of cylinder # 1, cylinder # 2, cylinder # 4, cylinder # 3, cylinder # 1, and so on. Further, in the internal combustion engine, fuel injection by the injector 150 is performed during the intake stroke, during the compression stroke, just before the end of the compression stroke, or a combination thereof according to the operating state and combustion state of the internal combustion engine. Do.

  In FIG. 4, in the HCCI operation region of the internal combustion engine, as described above, the injector 150 is set so that the air-fuel ratio (A / F) of the premixed gas in the cylinder 110 is in a lean state of 15 to 30. By controlling the fuel injection amount and the opening / closing of the throttle valve, combustion is performed by self-ignition without ignition by the discharge from the first and second spark plugs 70a, 70b. Further, in the SI operation region (A) having a lower load than the HCCI operation region of the internal combustion engine, the air-fuel mixture in the cylinder 110 is discharged at a predetermined timing from the first and second spark plugs 70a and 70b. Combustion is performed by flame propagation by spark ignition (SI). Specifically, the SI operation region (A) is a traveling condition in which the vehicle is hardly stepped on the accelerator, such as when the vehicle is traveling on a long downhill, except during idling, and the temperature of the cylinder 110 becomes considerably low. Consider combustion. Further, in the SI operation region (B) at the time of high load or high rotation of the internal combustion engine, an air-fuel ratio (A / F) in the cylinder 110 is formed into an air-fuel mixture close to the rich side, and at a predetermined timing. Combustion is performed by flame propagation by spark ignition (SI), which is burned by discharge from the first and second spark plugs 70a and 70b.

  In FIG. 5, at the time of flame propagation determination in the SI operation regions (A) and (B) of the internal combustion engine, the intake valve 132 is pushed down by the intake cam 134, and the piston 120 is lowered toward the intake bottom dead center. Thus, an intake stroke in which outside air is introduced from the intake port 130 is performed. The intake and exhaust valves 132 and 142 are both closed, and a compression stroke is performed in which the inside of the cylinder 110 is increased to a specified compression ratio by raising the piston 120 toward the compression top dead center. During the compression stroke, tumble (vertical vortex) is generated by the outside air introduced by the intake stroke, and when the fuel is injected by the injector 150 during the compression stroke, the injected fuel causes the fuel and the outside air to be separated by the tumble. Mixed. Further, the intake and exhaust valves 132 and 142 are both closed, and when discharged by the first spark plug 70a, the air-fuel mixture in the cylinder 110 explodes and the piston 120 moves toward the combustion bottom dead center. A lowering combustion stroke is performed. Discharge from the first spark plug 70a provided on the intake side during the combustion stroke causes flame propagation in which combustion spreads from the air-fuel mixture existing on the air intake side to the air-fuel mixture existing on the exhaust side.

  In FIG. 6, in the combustion state determination device for determining the flame propagation of the internal combustion engine, the switch element 90a is brought into contact with the ground side by the ECU, and the secondary coil 30a of the first ignition coil 10a is connected to the low pressure side. Connected to ground. The switch element 90b is brought into contact with the Zener diode 82 side by the ECU, and the secondary coil 30b of the second ignition coil 10b is connected to the ion current detecting means 80. As a result, a bias power source is generated in the capacitor 85 by the secondary coil 30b of the second ignition coil 10b, and the ion current generated in the cylinder 110 is detected only by the second ignition plug 70b.

  In FIG. 7, the second ignition coil 10b is advanced at a timing at which discharge from the second ignition plug 70b is performed in the cylinder 110 on the advance side of the fuel injection from the injector 150. An ignition signal is supplied from the ECU to the second igniter 50b. When an ignition signal is supplied to the second igniter 50b, the primary current from the power source 60 is charged to the primary coil 20b of the second ignition coil 10b. Further, the ECU cuts off the ignition signal to the second igniter 50b to cut off the primary current charged in the primary coil 20b. The electromagnetic induction induces the 2nd of the second ignition coil 10b. A high voltage is generated in the secondary coil 30b.

  The high voltage generated in the secondary coil 30b is discharged from the second spark plug 70b, and the capacitor 85 is charged with a bias power source. Accordingly, since the second spark plug 70b is discharged before fuel injection into the cylinder 110 of the cylinder 100, the cylinder 100 is ignited by the discharge of the second spark plug 70b. Absent.

  The first ignition coil 10a is supplied with an ignition signal from the ECU to the first igniter 50a so that the discharge is performed at the timing when the piston 120 reaches the compression top dead center. Further, when an ignition signal is supplied to the first igniter 50a, the primary current from the power source 60 is charged to the primary coil 20a of the first ignition coil 10a.

  In addition, the ECU cuts off the ignition signal to the first igniter 50a, thereby cutting off the primary current charged in the primary coil 20a, and the electromagnetic induction induces the 2 of the first ignition coil 10a. A high voltage is generated in the secondary coil 30a. Further, the first spark plug 70a is discharged at a timing when the piston 120 of the cylinder 100 becomes a compression top dead center. As a result, the air-fuel mixture present in the cylinder 110 is ignited and burned by the discharge of the first spark plug 70a.

  In addition, combustion starts from the vicinity of the first spark plug 70a provided at the upper end in the cylinder 110 by discharge from the first spark plug 70a, and spreads to the entire area of the cylinder 110 by flame propagation to the exhaust side. Combustion extends to the vicinity of the provided second spark plug 70b. Further, an ion current generated between the electrodes of the second spark plug 70b is detected when combustion occurs on the exhaust side of the cylinder 110 using the voltage stored in the capacitor 85 as a bias power source.

  Further, the ionic current flowing between the electrodes of the second spark plug 70b is the detection resistor 86b → the resistor 86a → the capacitor 85 → the secondary coil 30b → the second spark plug 70b shown in FIG. It flows in the route. Further, the operational amplifier 88 outputs an output signal to the ECU according to the detected amount of ion current, and the ECU detects an ion current having a waveform in the figure.

  Further, from the discharge of the first spark plug 70a to the second spark plug 70b side from the first spark plug 70a side in the cylinder 110 within the time when the ECU detects the ion current with the second spark plug 70b. The state of flame propagation to can be determined. For example, if the ion spark current cannot be detected by the second spark plug 70b even though the first spark plug 70a is discharged, it can be determined that flame propagation is not accurately performed. . Further, if the time until the second spark plug 70b detects an ionic current after the discharge of the first spark plug 70a is retarded, the fuel from the injector 150 is thin or the EGR amount It can be determined that there are too many.

  In FIG. 8, when determining the combustion state in the SI operation regions (A) and (B) of the internal combustion engine, the intake valve 132 is pushed down by the intake cam 134 and the piston 120 is lowered toward the intake bottom dead center. Thus, an intake stroke in which outside air is introduced from the intake port 130 is performed. The intake and exhaust valves 132 and 142 are both closed, and a compression stroke is performed in which the inside of the cylinder 110 is increased to a specified compression ratio by raising the piston 120 toward the compression top dead center. During the compression stroke, tumble (vertical vortex) is generated by the outside air introduced by the intake stroke, and when the fuel is injected by the injector 150 during the compression stroke, the injected fuel causes the fuel and the outside air to be separated by the tumble. Mixed. Further, both the intake and exhaust valves 132 and 142 are closed, and when discharged by the first and second spark plugs 70a and 70b, the air-fuel mixture in the cylinder 110 explodes and the piston 120 is burned. A combustion stroke that goes down to the dead center occurs.

  In FIG. 9, in the combustion state determination device at the time of combustion determination of the internal combustion engine, the switch elements 90a and 90b are brought into contact with the Zener diode 82 side by the ECU, and the first and second ignition coils 10a and 10b are connected. The secondary coils 30a and 30b are connected to the ion current detecting means 80. Accordingly, a bias power source is generated in the capacitor 85 by the secondary coils 30a and 30b of the first and second ignition coils 10a and 10b, and the ionic current generated in the cylinder 110 is converted into the first and second ions. Are detected by the spark plugs 70a and 70b.

  In FIG. 10, the first and second ignition coils 10a and 10b are connected to the first and second igniters 50a and 50b from the ECU so that the piston 120 is discharged at the timing when the compression top dead center is reached. Is supplied with an ignition signal. When an ignition signal is supplied to the first and second igniters 50a and 50b, a primary current from the power source 60 is supplied to the primary coils 20a and 20b of the first and second ignition coils 10a and 10b. Is charged. Further, the ECU cuts off the ignition signal to the first and second igniters 50a and 50b to cut off the primary current charged in the primary coils 20a and 20b, and the electromagnetic induction induces the first current. A high voltage is generated in the secondary coils 30a and 30b of the second ignition coils 10a and 10b.

  Further, the high voltage generated in the secondary coils 30a and 30b of the first and second ignition coils 10a and 10b is discharged from the first and second ignition plugs 70a and 70b, and also to the capacitor 85. The bias power supply is charged. As a result, the first and second ignition coils 10a and 10b are simultaneously discharged at the timing when the compression top dead center is reached, so that the first and second ignition plugs 70a and 70b discharge simultaneously in the cylinder 110. The air-fuel mixture existing on the intake and exhaust sides is ignited and burned.

  Further, an ion current generated between the electrodes of the first and second spark plugs 70a and 70b due to combustion in the cylinder 110 is detected by using the voltage stored in the capacitor 85 as a bias power source. Further, the ionic current detection means 80 synthesizes the ionic current generated between the electrodes of the first and second spark plugs 70a, 70b and outputs it to the ECU.

  The ionic current flowing between the electrodes of the first and second spark plugs 70a and 70b is the detection resistor 86b → the resistor 86a → the capacitor 85 → the secondary coils 30a and 30b → shown in FIG. It flows through the path of the first and second spark plugs 70a, 70b. Further, the operational amplifier 88 outputs an output signal to the ECU according to the detected amount of ion current, and the ECU detects an ion current having a waveform in the figure.

  The combustion state can be determined by detecting the ion current synthesized by the ECU at the first and second spark plugs 70a, 70b from the discharge of the first and second spark plugs 70a, 70b. . For example, if the ECU does not detect the ionic current synthesized by the first and second spark plugs 70a and 70b, it can be determined that misfiring has occurred in the combustion of the cylinder 100, and the ECU If a knock component is superimposed on the ionic current synthesized by the first and second spark plugs 70a and 70b, it can be determined that knocking has occurred in the combustion of the cylinder 100. Further, if the waveform of the ionic current synthesized by the first and second spark plugs 70a and 70b in the ECU is advanced, it is determined that preignition has occurred in the combustion of the cylinder 100. Can do.

  In FIG. 11, when determining the combustion state in the HCCI operation region of the internal combustion engine, the intake valve 132 is pushed down by the intake cam 134, and the piston 120 is lowered toward the intake bottom dead center, so that the intake port 130 An intake stroke in which outside air is introduced is performed. The intake and exhaust valves 132 and 142 are both closed, and a compression stroke is performed in which the inside of the cylinder 110 is increased to a specified compression ratio by raising the piston 120 toward the compression top dead center. During the compression stroke, tumble (vertical vortex) is generated by the outside air introduced by the intake stroke, and when the fuel is injected by the injector 150 during the compression stroke, the injected fuel causes the fuel and the outside air to be separated by the tumble. Mixed. In addition, the intake and exhaust valves 132 and 142 are both closed, and the combustion mixture in which the air-fuel mixture in the cylinder 110 is exploded from self-ignition due to the compression stroke, and the piston 120 is lowered toward the combustion bottom dead center. Happens.

  The combustion state determination device in the HCCI operation region of the internal combustion engine is the same as in FIG. 9, and the combustion state determination device at the time of combustion determination of the internal combustion engine is the switch element 90a on the Zener diode 82 side by the ECU. The secondary coil 30a of the first ignition coil 10a is connected to the ion current detecting means 80. The switch element 90b is brought into contact with the Zener diode 82 side by the ECU, and the secondary coil 30b of the second ignition coil 10b is connected to the ion current detecting means 80. Accordingly, a bias power source is generated in the capacitor 85 by the secondary coils 30a and 30b of the first and second ignition coils 10a and 10b, and the ionic current generated in the cylinder 110 is converted into the first and second ions. This is detected by the spark plug 70b.

  In FIG. 12, the first and second ignition coils 10a, 10b are connected to the first and second ignition plugs 70a, 70a in the cylinder 110 on the more advanced side than the fuel injection from the injector 150 is performed. An ignition signal is supplied from the ECU to the first and second igniters 50a and 50b at the timing when the discharge from 70b is performed. When an ignition signal is supplied to the first and second igniters 50a and 50b, a primary current from the power source 60 is supplied to the primary coils 20a and 20b of the first and second ignition coils 10a and 10b. Is charged. Further, the ECU cuts off the ignition signal to the first and second igniters 50a and 50b to cut off the primary current charged in the primary coils 20a and 20b, and the electromagnetic induction induces the first current. A high voltage is generated in the secondary coils 30a and 30b of the second ignition coils 10a and 10b.

  The high voltage generated in the first and secondary coils 30a and 30b is discharged from the first and second spark plugs 70a and 70b, and the capacitor 85 is charged with a bias power source. Accordingly, since the first and second spark plugs 70a and 70b are discharged before fuel injection into the cylinder 110 of the cylinder 100, the discharge of the first and second spark plugs 70a and 70b is performed. Thus, the cylinder 100 is not ignited.

  In addition, the ion current generated between the electrodes of the first and second spark plugs 70a and 70b is detected by the combustion in the cylinder 110 using the voltage stored in the capacitor 85 as a bias power source. Further, the ionic current detection means 80 synthesizes the ionic current generated between the electrodes of the first and second spark plugs 70a, 70b and outputs it to the ECU.

  Also, the ionic current flowing between the electrodes of the second spark plug 70b is the detection resistor 86b → the resistor 86a → the capacitor 85 → the secondary coils 30a and 30b → the first and second resistors shown in FIG. It flows through the path of the two spark plugs 70a, 70b. Further, the operational amplifier 88 outputs an output signal to the ECU according to the detected amount of ion current, and the ECU detects an ion current having a waveform in the figure.

  Further, the combustion state can be determined by detecting the ionic current synthesized by the ECU at the first and second spark plugs 70a and 70b from the HCCI combustion of the cylinder 100. For example, if the ECU does not detect the ionic current synthesized by the first and second spark plugs 70a and 70b, it can be determined that misfire has occurred in the HCCI combustion of the cylinder 100, and the ECU Thus, if a knock component is superimposed on the ion current synthesized by the first and second spark plugs 70a and 70b, it can be determined that knocking has occurred in the combustion of the cylinder 100. Further, if the waveform of the ionic current synthesized by the first and second spark plugs 70a and 70b in the ECU is advanced, it is determined that preignition has occurred in the combustion of the cylinder 100. Can do.

  With the above configuration, the second ignition coil 10b discharges from the second spark plug 70b into the cylinder 110 on the advance side of the fuel injection from the injector 150, and Ions generated between the electrodes of the second spark plug 70b due to the discharge of one spark plug 70a spreading from the combustion in the vicinity of the first spark plug 70a provided at the upper end of the cylinder 110 into the cylinder 110 By detecting the current, the second spark plug 70b is discharged before fuel is injected into the cylinder 110 of the cylinder 100. Therefore, the cylinder 100 is ignited by the discharge of the second spark plug 70b. Without this, the state of flame propagation in the cylinder 110 can be determined from the discharge of the first spark plug 70a by the time when the ECU detects the ionic current at the second spark plug 70b. As a result, accurate flame propagation can be determined even if the internal combustion engine is a minute ion current generated by lean combustion with lean fuel or combustion with a large amount of EGR.

  The first and second ignition coils 10a and 10b discharge at a timing when the piston 120 reaches compression top dead center, and the ECU performs the first and second ignitions from combustion in the cylinder 110. By detecting the ionic current synthesized by the plugs 70a and 70b and determining the combustion state, the combustion speed is improved by the discharge from the first and second spark plugs 70a and 70b, and the internal combustion engine is operated with a lean fuel. The combustion state can be accurately determined even with a minute ion current generated by lean combustion due to or combustion by a large amount of EGR.

  The first and second ignition coils 10a and 10b are connected to the cylinder 110 from the first and second ignition plugs 70a and 70b on the advance side of the fuel injection from the injector 150. The ionic current detection means 80 determines the combustion state by detecting the ionic current generated between the electrodes of the first and second spark plugs 70a, 70b from the HCCI combustion of the cylinder 100. Thus, the combustion state can be accurately determined even with a minute ion current due to combustion of the HCCI engine having a high air-fuel ratio.

  The secondary coils 30a and 30b of the first and second ignition coils 10a and 10b are connected to the ion current detection means 80 via switch elements 90a and 90b, and the ion current detection is performed by switching the contact. The second spark plug 70b detects the ion current from the discharge of the first spark plug 70a from the minute ion current without changing the ion current detection means 80 by making the means 80 or the ground conductive. It is possible to switch between control for determining the flame propagation up to and control for determining the combustion state from the ion current synthesized by the first and second spark plugs 70a and 70b. With this effect, it is possible to determine not only lean combustion with lean fuel and combustion with a large amount of EGR but also a combustion state corresponding to a wide range of operating conditions of the internal combustion engine with a single device.

As a modification of the first embodiment, the first and second ignition coils 10a and 10b supply the same output. For example, the first ignition coil 10a has a high output. A different output may be supplied by each ignition coil, for example, for the ignition, and the second ignition coil 10b for a sub-ignition that supplies a lower output than the first ignition coil 10a. Further, the ion current detecting means 80 may have any circuit configuration as long as the ion current generated in the cylinder 110 can be detected by the first and second spark plugs 70a and 70b. Furthermore, the switch elements 90a and 90b may be configured using elements other than relays.
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  Further, although the internal combustion engine is a four-cylinder HCCI engine, the effect of the present invention can also be obtained as a gasoline engine or a diesel engine having a plurality of cylinders. Further, in the internal combustion engine, the compression ratio of the cylinder 110 is set in the range of 11 to 13, but is changed according to SI combustion or HCCI combustion.

  Further, the first spark plug 70a is disposed at the upper end in the cylinder 110. However, the first spark plug 70a may be disposed at an arbitrary position depending on design circumstances as long as it is away from the second spark plug 70b. The second spark plug 70b is also disposed on the exhaust side in the cylinder 110. However, it may be disposed at an arbitrary position depending on design circumstances as long as it is away from the first spark plug 70a. Further, the internal combustion engine includes the injector 150 on the intake port 130 side of the cylinder 110 as a direct injection engine that directly injects gasoline into the cylinder 110. However, the intake port 130 also includes an injector. Further, it may be a direct injection engine combined with a port injection.

  In addition, the second ignition coil 10b at the time of flame propagation determination in the SI operation regions (A) and (B) of the internal combustion engine has the cylinder 110 on the advance side with respect to the fuel injection from the injector 150. Since the discharge from the second spark plug 70b only needs to be performed inside, the discharge from the second spark plug 70b may be performed during the intake stroke into the cylinder 110. Further, the first and second ignition coils 10a and 10b at the time of determining the combustion state in the HCCI operation region of the internal combustion engine are placed in the cylinder 110 on the advance side with respect to the fuel injection from the injector 150. Since the discharge from the first and second spark plugs 70a and 70b only needs to be performed, the discharge from the first and second spark plugs 70a and 70b is performed during the intake stroke into the cylinder 110. Also good.

10a: First ignition coil
10b: Second ignition coil
50a: First igniter
50b: Second igniter
60: Power supply
70a: First spark plug
70b: Second spark plug
80: Ion current detection means
90a, 90b: Switch element
100: cylinder
110: Cylinder
120: Piston
122: Crank
124: Crankshaft
130: Inlet port
132: Intake valve
134: Intake cam
136: Intake camshaft
140: Exhaust port
142: Exhaust valve
144: Exhaust cam
146: Exhaust camshaft
150: Injector

Claims (5)

Two spark plugs 70a, 70b arranged at a certain distance in a single cylinder 100 of the internal combustion engine;
Two ignition coils 10a, 10b individually provided in the spark plugs 70a, 70b;
Ionic current detection means 80 for detecting an ionic current generated between the electrodes of the spark plugs 70a, 70b when the air-fuel mixture in the cylinder 100 of the internal combustion engine burns;
Combustion state determination means for determining the combustion state of the internal combustion engine from the detected ion current,
The second spark plug 70b performs an ignition operation during the exhaust stroke of the internal combustion engine or the intake stroke of the direct injection engine.
The first spark plug 70a performs an ignition operation during a compression stroke of the internal combustion engine,
The ion current detection means 80 detects an ion current generated between the electrodes of the second spark plug 70b,
The combustion state determination means performs a flame propagation determination from the time from when the first spark plug 70a discharges until the second spark plug 70b detects an ionic current. apparatus. The two spark plugs 70a and 70b perform an ignition operation during the compression stroke,
The ion current detecting means 80 detects an ion current generated between the electrodes of the two spark plugs 70a and 70b,
2. The combustion state of the internal combustion engine according to claim 1, wherein the combustion state determination unit performs combustion determination of at least one of combustion state deterioration including pre-fire in the cylinder 100, pre-ignition, and knocking. Judgment device. One ionic current detection means 80 is provided for the two ignition coils 10a and 10b arranged in the single cylinder 100,
3. The internal combustion engine according to claim 1, wherein the secondary coils 30 a and 30 b of the two ignition coils 10 a and 10 b are connected to the ion current detecting means 80 via switch elements 90 a and 90 b. Combustion state determination device.   The internal combustion engine combustion state determination device according to any one of claims 1 to 3, wherein the internal combustion engine is either a diesel engine or a uniform premixed compression ignition type engine. The two spark plugs 70a and 70b perform an ignition operation before fuel injection to the cylinder 100 of the internal combustion engine,
The ion current detecting means 80 detects an ion current generated between the electrodes of the two spark plugs 70a and 70b,
5. The combustion state of the internal combustion engine according to claim 4, wherein the combustion state determination unit performs combustion determination of at least one of deterioration of combustion state including misfire in the cylinder 100, pre-ignition, and knocking. Judgment device.

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