JP2014029128A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To strike a balance between fuel combustion stabilization in a combustion chamber of a cylinder and effective improvement of fuel consumption.SOLUTION: In a device of controlling a spark ignition type internal combustion engine, an electric field produced in a combustion chamber of a cylinder via an antenna facing the inside of the combustion chamber and spark discharge generated between a center electrode and an earth electrode of an ignition plug interact with each other to produce plasma in the combustion chamber, active firing can be performed which fires air-fuel mixture, and in addition an EGR device is attached in which part of exhaust flows back and mixes in intake air. Fuel consumption that can be reduced by an increase in an EGR gas amount caused by performance of the active firing, and fuel consumption required for covering electric power consumed by the active firing are calculated, and the active firing is performed under the condition that the former exceeds the latter.

Description

  The present invention relates to a control device for controlling a spark ignition internal combustion engine.

While lowering the combustion temperature and reducing emissions of NO _x, EGR to reduce the pumping loss (Exhaust Gas Recirculation) device is well known internal combustion engine which is attached (e.g., see Patent Document 1). The EGR device connects an exhaust path and an intake path via an EGR passage, and part of combustion gas generated in the cylinder is recirculated to the intake path via the EGR path and mixed into the intake air.

  By performing EGR, it is possible to improve fuel efficiency. On the other hand, if the amount of EGR gas mixed into the intake air is excessive, the combustion of fuel in the combustion chamber of the cylinder becomes unstable, Sometimes misfires occur. In particular, when EGR is performed when the temperature of the internal combustion engine is low, combustion instability becomes significant. Conventionally, EGR is not performed during warm-up operation, or the amount of EGR gas is reduced.

  Recently, in order to reliably ignite the air-fuel mixture in the combustion chamber of the cylinder and to obtain a stable flame, a spark discharge is generated in the spark plug, and an electric field generating circuit, in other words, a microwave or a high-frequency oscillator output by a magnetron Attempts have been made to "active ignition" that radiates high-frequency waves output from the engine into the combustion chamber (see, for example, Patent Document 2 or 3 below). According to the active ignition method, a microwave or high-frequency electric field is formed in the space between the center electrode and the ground electrode of the spark plug, and the plasma generated in this electric field grows to become the beginning of flame propagation combustion. Flame kernels are generated.

  If active ignition is used in combination, it seems that the problem of instability of combustion caused by EGR can be alleviated or eliminated. However, in order to radiate microwaves or high-frequency waves into the combustion chamber, electric power is consumed, and the electric power is generated by the rotating alternator in response to the driving force supplied from the internal combustion engine. It is impossible to deny the possibility that the fuel efficiency improvement effect due to will be canceled and the fuel efficiency deteriorated.

JP 2004-245107 A JP 2011-159477 A JP 2011-0664162 A

  An object of the present invention is to achieve both the stabilization of fuel combustion in the combustion chamber of a cylinder and the improvement of effective fuel consumption.

  In the present invention, plasma is generated in the combustion chamber by interacting the electric field generated in the combustion chamber via the antenna facing the combustion chamber of the cylinder and the spark discharge generated between the center electrode and the ground electrode of the spark plug. A spark ignition type internal combustion engine that is capable of performing active ignition to generate and ignite an air-fuel mixture, and that is accompanied by an EGR device that recirculates a part of exhaust gas and mixes it with intake air; Compared to the situation where EGR is not performed without active ignition or the amount of EGR gas is smaller, the fuel consumption that can be reduced by increasing the amount of EGR gas by performing active ignition, and the power consumed for active ignition A control device for an internal combustion engine, which calculates an amount of fuel consumption necessary to cover the fuel and performs active ignition on condition that the former exceeds the latter You configure.

  In addition, the electric field generated in the combustion chamber via the antenna facing the combustion chamber of the cylinder interacts with the spark discharge generated between the center electrode and the ground electrode of the spark plug to generate plasma in the combustion chamber. The spark ignition type internal combustion engine which can perform active ignition for igniting the air-fuel mixture, and which is accompanied by an EGR device that recirculates a part of the exhaust gas and mixes in the intake air, A control apparatus for an internal combustion engine is characterized in that active ignition is performed on condition that the amount becomes larger than a limit amount at which combustion of fuel in the cylinder does not become unstable.

  According to the present invention, it is possible to achieve both the stabilization of fuel combustion in the combustion chamber of the cylinder and the improvement of effective fuel consumption.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The figure which shows the electric field generator in the same embodiment. The figure explaining the specific structure of an electric field generator. The circuit diagram of the H bridge which is an element of an electric field generator. The figure which shows the relationship between a request | requirement load and a request | requirement EGR rate. The flowchart which shows the example of the procedure of the process which the control apparatus of the embodiment implements. The flowchart which shows the example of a procedure of the process which the control apparatus of other embodiment of this invention implements. The flowchart which shows the example of a procedure of the process which the control apparatus of other embodiment of this invention implements.

  <First Embodiment> An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1.

  FIG. 2 shows an electric circuit for spark ignition. The spark plug 12 receives spark voltage generated by the ignition coil 14 and causes spark discharge between the center electrode and the ground electrode. The ignition coil 14 is integrally incorporated in a coil case together with an igniter 13 that is a semiconductor switching element.

  The internal combustion engine of the present embodiment is accompanied by an electric field generator that generates an electric field in the combustion chamber of the cylinder 1. This electric field generator is intended to generate plasma in a combustion chamber. Examples of the electric field generator include an AC voltage generation circuit that applies a high-frequency AC voltage, a pulsating voltage generation circuit that applies a high-frequency pulsating voltage, and the like.

  As shown in FIGS. 2 to 4, the electric field generator for generating a high frequency includes a circuit that converts a low-voltage direct current into a high-voltage alternating current using an in-vehicle battery as a power source. Specifically, a DC-DC converter 61 that boosts a DC voltage of about 12 V provided by the battery to 100 V to 500 V, an H-bridge circuit 62 that converts DC output from the DC-DC converter 61 into AC, and an H-bridge A step-up transformer 63 that boosts the alternating current output from the circuit 62 to a higher voltage is used as a constituent element.

  A first diode 64 and a second diode 65 are preferably provided at the output end of the electric field generator. The first diode 64 has a cathode connected to the signal line of the secondary winding of the step-up transformer 63 and an anode connected to a mixer 66 that is a node with the ignition coil 14. The second diode 65 has an anode connected to the ground line of the secondary winding of the step-up transformer 63 and a cathode grounded. The first diode 64 and the second diode 65 play a role of blocking the negative high-voltage pulse current flowing from the secondary side of the ignition coil 14 at the ignition timing.

  When the air-fuel mixture is ignited by the active ignition method, the high-frequency voltage oscillated by the electric field generator is applied to the center electrode of the spark plug 12 almost simultaneously with the start of the spark discharge, immediately before the start of the spark discharge or immediately after the start of the spark discharge. That is, the center electrode of the spark plug 12 facing the combustion chamber of the cylinder 1 is an antenna that radiates an electric field. Thereby, a high frequency electric field is formed in the space between the center electrode of the spark plug 12 and the ground electrode in the combustion chamber. Then, a plasma is generated by performing a spark discharge in a high-frequency electric field, and this plasma generates a large radical plasma flame nucleus that starts flame propagation combustion.

  In the above, the flow of electrons due to the spark discharge and the ions and radicals generated by the spark discharge are vibrated and meandered by the influence of the electric field, resulting in a long path length and a dramatic increase in the number of collisions with surrounding water and nitrogen molecules. This is due to the increase. Water molecules and nitrogen molecules that have been struck by ions and radicals become OH radicals and N radicals, and the surrounding gas that has been struck by ions and radicals is also ionized, that is, a plasma state. In addition, the region of ignition of the air-fuel mixture increases and the flame kernel also increases. As a result, the two-dimensional ignition by only the spark discharge is amplified to the three-dimensional ignition, and the combustion rapidly propagates into the combustion chamber and expands at a high combustion speed.

  Incidentally, when a pulsating voltage generating circuit is employed as the electric field generating device, the pulsating voltage generating circuit may be any circuit that generates a DC voltage whose voltage periodically changes, and its waveform may be arbitrary. The pulsating voltage includes a pulse voltage that varies from a reference voltage (which may be 0V) to a constant voltage in a constant cycle, a voltage obtained by half-wave rectifying an AC voltage, a voltage obtained by adding a DC bias to the AC voltage, and the like. The high-frequency voltage oscillated by the electric field generator preferably has a frequency of about 200 kHz to 3000 kHz and an amplitude of about 3 kVp-p to 10 kVp-p.

  An intake passage 3 for supplying intake air to the cylinder 1 of the internal combustion engine takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for exhausting the exhaust from the cylinder 1 guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  An external EGR device 2 is attached to the internal combustion engine of the present embodiment. The external EGR device 2 realizes a so-called high-pressure loop EGR. The EGR device 21 communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3, and the EGR passage 21. The EGR cooler 22 provided in the EGR passage and the EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of EGR gas flowing through the EGR passage 21 are used as elements. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, specifically to a surge tank 33.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from a rotation sensor that detects the rotation angle of the crankshaft and the engine speed. An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (required load), and a brake depression amount that is output from a sensor that detects the amount of depression of the brake pedal Signal d, intake air temperature / intake pressure signal e output from a temperature / pressure sensor that detects intake air temperature and intake pressure in the intake passage 3 (especially surge tank 33), output from a water temperature sensor that detects engine coolant temperature Is output from a sensor (or shift position switch) for obtaining the coolant temperature signal f and the shift lever range. Futorenji signal g, a cam angle signal (G signal) which is output from the cam angle sensor at a plurality of cam angle of the intake camshaft or an exhaust camshaft h the like are input.

  From the output interface, the ignition signal i for the igniter of the spark plug 12, the fuel injection signal j for the injector 11, the opening operation signal k for the throttle valve 32, and the electric field (ie, high frequency) for the electric field generator. ) The opening operation signal m and the like are output to the generation command signal 1 and the EGR valve 23.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the amount of intake air. Based on the rotational speed, the intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR amount) ), Various operating parameters such as whether or not to generate an electric field in the combustion chamber and the timing of the electric field generation are determined. As the operation parameter determination method itself, a known method can be adopted. Thus, the ECU 0 applies various control signals i, j, k, l, m corresponding to the operation parameters via the output interface.

  FIG. 5 shows an outline of the relationship between the required load corresponding to the accelerator pedal depression amount and the EGR rate indicating the EGR gas amount required for the intake air charged in the cylinder 1. Basically, the required EGR rate is the highest in the medium load region and lower in the low load region and the high load region. In the low load region, the required EGR rate decreases as the required load decreases. In the high load region, the required EGR rate decreases as the required load increases.

  If the EGR rate of the intake air charged in the cylinder 1 is increased, the pumping loss of the internal combustion engine is reduced, and an effective improvement in fuel consumption can be expected. However, if the EGR rate is excessively high, the combustion of fuel in the combustion chamber of the cylinder 1 becomes unstable and sometimes misfires. In particular, when the temperature of the internal combustion engine is low, combustion instability becomes significant. If the combustion becomes unstable, the engine speed will not be stable and the fluctuation will increase, or unburned fuel components will be discharged via the exhaust passage 4, which will be a problem. If the risk of instability of combustion is high, EGR is not executed regardless of the required EGR rate (EGR valve 23 is fully closed) or the EGR amount is reduced below the required EGR rate (the opening degree of EGR valve 23) To a degree of opening that does not match the required EGR rate).

  On the other hand, if the active ignition method is used, even if EGR is executed according to the required EGR rate, it is possible to avoid instability of combustion due to EGR. However, in order to radiate microwaves or high frequencies into the combustion chamber of the cylinder 1, power is consumed. The electric power is generated by an alternator (not shown) that rotates upon receiving a driving force from the internal combustion engine. In other words, since an increase in power consumption means an increase in fuel consumption, the execution of active ignition may cancel the fuel efficiency improvement effect by EGR, and may worsen the fuel efficiency.

  Therefore, in the present embodiment, compared to the situation where EGR is not performed without performing active ignition or the amount of EGR gas is smaller, the fuel consumption amount that can be reduced by increasing the amount of EGR gas by performing active ignition The fuel consumption required to cover the power consumed for active ignition is calculated, and active ignition is executed only when the former exceeds the latter.

  FIG. 6 shows a procedure example of processing executed by the ECU 0 according to the present embodiment in accordance with a program. First, the ECU 0 requests the required EGR rate corresponding to the current operation region, that is, the engine speed and load (accelerator opening degree, intake pressure, intake air flow rate or fuel injection amount flowing into the cylinder 1), cooling water temperature, intake air temperature, and the like. (Or EGR amount) and a limit EGR rate (or EGR amount) that does not cause instability of combustion in the combustion chamber of cylinder 1 without performing active ignition, for example, referring to map data Know (steps S1, S2). In the memory of the ECU 0 in advance, the required EGR rate that is advantageous for fuel consumption, obtained experimentally or by adaptation under various conditions such as the engine speed, engine load, and cooling water temperature, and the combustion Map data describing the value of the EGR rate with a sufficiently low risk of destabilization is stored. The ECU 0 searches the map using the current engine speed, load, cooling water temperature, intake air temperature, and the like as keys, and extracts and knows the required EGR rate and the EGR rate that does not cause combustion instability. The EGR rate that does not cause instability of combustion is equal to the required EGR rate depending on the operating region, cooling water temperature, intake air temperature, etc. (in the current situation, combustion does not become unstable even if EGR is performed) Or 0 (combustion may become unstable when EGR is performed under the present situation).

  Then, the ECU 0 knows the difference between the fuel consumption when the EGR rate is set so as not to cause instability of combustion and the fuel consumption when the required EGR rate is realized with reference to map data, for example. Obtain (step S3). The memory of the ECU 0 is obtained in advance experimentally or by adaptation under various conditions such as the engine speed, engine load, cooling water temperature, intake air temperature, and intake EGR rate (or EGR amount). Map data describing the value of fuel consumption is stored. The ECU 0 searches the map using the current engine speed, load, cooling water temperature, intake air temperature, etc. and the EGR rate as keys, and the fuel consumption when the EGR rate is set so as not to cause instability of combustion, The fuel consumption when the required EGR rate is realized is extracted. Then, the former is subtracted from the latter to know the fuel consumption saved by the control to the required EGR rate.

  In addition, the ECU 0 knows, for example, map data, fuel consumption for power consumed to generate a high-frequency electric field in the combustion chamber of the cylinder 1 by applying a high frequency to the electrode of the spark plug 12 (step). S4). In the memory of the ECU 0 in advance, experimentally under conditions such as various internal combustion engine loads and cooling water temperature (in this case, the temperature of the electrode of the spark plug 12 and the electric circuit for applying the high frequency electric field is suggested) or Stored is map data describing a value obtained by converting power consumption for generating an electric field in the combustion chamber into fuel consumption, which is obtained by conformance. The ECU 0 searches the map using the current engine load, cooling water temperature, and the like as keys, and extracts and knows the fuel consumption necessary for generating a high-frequency electric field in the combustion chamber. However, by measuring the current and voltage flowing through the electric circuit when applying a high frequency to the electrode of the spark plug 12, the power consumed to generate the high frequency electric field is measured, and the measured power consumption is consumed as fuel. You may make it convert into quantity.

  The ECU 0 then compares the fuel consumption saved by the control to the required EGR rate with the fuel consumption required to generate a high-frequency electric field in the combustion chamber (step S5), and the former fuel If the consumption exceeds the latter fuel consumption, the opening of the EGR valve 23 is operated to control the intake EGR rate to a size advantageous for fuel consumption reduction, that is, the required EGR rate (step S6). A high frequency electric field is applied to the electrode of the spark plug 12 to execute active ignition in the expansion stroke of 1 (step S7). Conversely, if the former fuel consumption is less than or equal to the latter fuel consumption, the intake EGR rate is controlled to be less than or equal to the required EGR rate with a low risk of causing instability of combustion (step S8), and active ignition is performed. No high frequency electric field is applied to the electrode of the spark plug 12 during the expansion stroke of the cylinder 1.

  In this embodiment, an electric field generated in the combustion chamber using the center electrode of the spark plug 12 facing the combustion chamber of the cylinder 1 as an antenna and a spark discharge generated between the center electrode and the ground electrode of the spark plug 12 are mutually connected. A spark ignition type internal combustion engine capable of generating active plasma for generating plasma in the combustion chamber and igniting the air-fuel mixture, and attached with an EGR device 2 that recirculates a part of the exhaust gas and mixes it with the intake air Fuel consumption that controls the engine and can be reduced by increasing the amount of EGR gas by performing active ignition compared to the situation where EGR is not performed without active ignition or the amount of EGR gas is smaller The amount of fuel consumed and the amount of fuel consumed to cover the power consumed for active ignition are calculated and active ignition is performed on condition that the former exceeds the latter. Ukoto to constitute a control apparatus 0 for an internal combustion engine characterized by.

  In the present embodiment, in view of the fact that the amount of EGR gas mixed into the intake air can be increased without destabilizing combustion by the active ignition method, the fuel consumption for the execution of active ignition and the increase control of the EGR rate are brought about. The improvement effect of fuel consumption was weighed and the active ignition was executed only when the improvement effect exceeded. According to the present embodiment, it is possible to achieve both the stabilization of fuel combustion in the combustion chamber of the cylinder 1 and the improvement of effective fuel consumption.

  <Second Embodiment> In this embodiment described below, active ignition is performed in a situation where combustion in the combustion chamber of the cylinder 1 becomes unstable when EGR is executed, particularly during a warm-up operation where the temperature of the internal combustion engine is low. The focus is on stabilizing combustion.

  The configurations of the internal combustion engine, the active ignition high-frequency generation circuit, the EGR device, and the like are the same as those in the first embodiment. Further, the basic function of the ECU 0 as the control device for the internal combustion engine is the same as that of the first embodiment.

  FIG. 7 shows a procedure example of processing executed by the ECU 0 according to the present embodiment in accordance with a program. The ECU 0 determines the required EGR rate (or EGR amount) corresponding to the current operating region, that is, the engine speed and load, the cooling water temperature, the intake air temperature, etc., and the non-combustion in the combustion chamber of the cylinder 1 without performing active ignition. The limit EGR rate (or EGR amount) that does not cause stabilization is obtained by referring to, for example, map data (steps S9 and S10). Step S9 is the same as step S1 of the first embodiment, and step S10 is the same as step S2 of the first embodiment.

  Then, the ECU 0 compares the required EGR rate with a limit EGR rate that does not cause instability of combustion (step S11), and if the former exceeds the latter, the intake EGR rate is set to the required EGR rate. A high frequency electric field is applied to the electrode of the spark plug 12 to execute active ignition in the expansion stroke of the cylinder 1 while operating the opening of the EGR valve 23 to control (step S13). Conversely, if the former required EGR rate is equal to or lower than the latter EGR rate, it means that the risk of instability of combustion is sufficiently small without performing active ignition. The active ignition is not executed in the expansion stroke of the cylinder 1 while controlling at a rate (step S14).

  In this embodiment, an electric field generated in the combustion chamber using the center electrode of the spark plug 12 facing the combustion chamber of the cylinder 1 as an antenna and a spark discharge generated between the center electrode and the ground electrode of the spark plug 12 are mutually connected. A spark ignition type internal combustion engine capable of generating active plasma for generating plasma in the combustion chamber and igniting the air-fuel mixture, and attached with an EGR device 2 that recirculates a part of the exhaust gas and mixes it with the intake air A control device 0 for an internal combustion engine that controls an engine and performs active ignition on condition that the amount of EGR gas becomes larger than a limit amount in which combustion of fuel in the cylinder 1 does not become unstable. Configured.

  In the present embodiment, in view of the fact that the amount of EGR gas mixed into the intake air can be increased without destabilizing combustion by the active ignition method, active ignition is performed when it is determined that there is a possibility of unstable combustion. Since it is determined to be executed, it is possible to perform EGR even during warm-up operation where EGR is conventionally stopped, and further improvement in fuel consumption can be expected. In addition, if there is little risk of destabilization of combustion even if the recirculation amount of EGR gas is increased to such an extent that the required EGR rate can be achieved, active ignition is not executed, so that excess power consumption and fuel consumption are reduced. Can be reduced.

  <Third Embodiment> This embodiment to be described next relates to whether or not to perform active ignition (and whether to increase or decrease the amount of EGR gas recirculated from the exhaust passage 4 to the intake passage 1). This is a combination of the determination process of one embodiment and the determination process of the second embodiment.

  The configurations of the internal combustion engine, the active ignition high-frequency generation circuit, the EGR device, and the like are the same as those in the first embodiment or the second embodiment. Further, the basic function of the ECU 0 as the control device for the internal combustion engine is the same as that of the first embodiment or the second embodiment.

  FIG. 8 shows a procedure example of processing executed by the ECU 0 according to the present embodiment in accordance with a program. The ECU 0 determines the required EGR rate (or EGR amount) corresponding to the current operating region, that is, the engine speed and load, the cooling water temperature, the intake air temperature, etc., and the non-combustion in the combustion chamber of the cylinder 1 without performing active ignition. The limit EGR rate (or EGR amount) that does not cause stabilization is obtained by referring to map data, for example (steps S15 and S16). Step S15 is the same as step S1 of the first embodiment or step S9 of the second embodiment, and step S16 is the same as step S2 of the first embodiment or step S10 of the second embodiment.

  Then, the ECU 0 compares the required EGR rate with a limit EGR rate that does not cause instability of combustion (step S17). If the former required EGR rate is less than or equal to the latter EGR rate, the risk of instability of combustion is sufficiently small even if active ignition is not executed. Therefore, the intake EGR rate is controlled to the required EGR rate. However (step S18), the active ignition is not executed in the expansion stroke of the cylinder 1, that is, the high frequency electric field is not applied to the electrode of the spark plug 12 in the expansion stroke of the cylinder 1.

  In contrast, if the former required EGR rate exceeds the latter EGR rate, then the ECU 0 realizes the fuel consumption and the required EGR rate when the EGR rate is set so as not to cause instability of combustion. The difference with the fuel consumption at the time of doing is acquired with reference to map data, for example (step S19). Step S19 is the same as step S3 of the first embodiment.

  In addition, the ECU 0 knows, for example, map data, fuel consumption for power consumed to generate a high-frequency electric field in the combustion chamber of the cylinder 1 by applying a high frequency to the electrode of the spark plug 12 (step). S20). Step S20 is the same as step S4 of the first embodiment.

  The ECU 0 then compares the fuel consumption saved by the control to the required EGR rate with the fuel consumption required to generate a high-frequency electric field in the combustion chamber (step S21), and the former fuel If the consumption exceeds the latter fuel consumption, the opening of the EGR valve 23 is manipulated to control the intake EGR rate to a size advantageous for fuel consumption reduction, that is, the required EGR rate (step S22). A high frequency electric field is applied to the electrode of the spark plug 12 to execute active ignition in the expansion stroke of 1 (step S23). Conversely, if the former fuel consumption is less than or equal to the latter fuel consumption, the intake EGR rate is controlled to be less than or equal to the required EGR rate with a low risk of causing instability of combustion (step S24), and active ignition is performed. No high frequency electric field is applied to the electrode of the spark plug 12 during the expansion stroke of the cylinder 1.

  According to the present embodiment, the active ignition is not executed in a situation where there is no fear of unstable combustion, so that it is possible to reduce extra power consumption and thus fuel consumption. Furthermore, in situations where there is a risk of destabilization of combustion, when the improvement effect exceeds the fuel consumption for the power consumed for execution of active ignition and the improvement effect of the fuel consumption brought about by the increase control of the EGR rate, the improvement effect exceeds Since the active ignition is executed and the EGR gas amount is suppressed without executing the active ignition when the improvement effect is lower, the combustion of the fuel in the combustion chamber of the cylinder 1 is stabilized and the effective fuel consumption is reduced. It is possible to achieve both improvement.

  The present invention is not limited to the embodiment described in detail above. An electric field generator for generating an electric field in a combustion chamber for the purpose of generating plasma in a combustion chamber of a cylinder of an internal combustion engine is an AC voltage generating circuit that applies a high-frequency AC voltage, or a pulsating voltage that applies a high-frequency pulsating voltage. It is not limited to the generation circuit. A microwave generator or the like may be employed as the electric field generator.

  The microwave generator includes a magnetron that uses a vehicle-mounted battery as a power source and a control circuit that controls the magnetron. The microwave generator is electrically connected to the spark plug via a waveguide, a coaxial cable, etc., and the microwave output from the magnetron is applied to the spark plug and radiated from the center electrode into the combustion chamber of the cylinder. Is possible.

  The microwave generated by the magnetron is applied almost simultaneously with the start of the spark discharge, immediately before the start of the spark discharge or immediately after the start of the spark discharge. At this time, the ECU inputs an electric field (ie, microwave) generation command signal to a control circuit that controls the magnetron. It is also conceivable to apply the microwave by the magnetron and the high induction voltage by the ignition coil in a superimposed manner to the center electrode of the spark plug.

  The antenna that radiates an electric field into the combustion chamber of the cylinder is not limited to the center electrode of the spark plug. In addition to the spark plug, an internal combustion engine in which an antenna for radiating an electric field is installed in the combustion chamber of the cylinder may be configured.

  The EGR device is not limited to a high pressure loop EGR device. The upstream side of the compressor of the exhaust turbocharger in the intake passage and the downstream side of the turbine (and further the catalyst) of the exhaust turbocharger in the exhaust passage are connected via the EGR passage, and low temperature and low pressure EGR gas is supplied. The present invention may be applied to control of an internal combustion engine attached with a low-pressure loop EGR device that recirculates.

  In addition, the specific configuration of each part, the specific processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be used for controlling an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
1 ... cylinder 12 ... antenna (ignition plug)
2 ... EGR device

Claims (2)

Plasma is generated in the combustion chamber by mixing the electric field generated in the combustion chamber via the antenna facing the combustion chamber of the cylinder and the spark discharge generated between the center electrode and the ground electrode of the spark plug, and mixing A spark ignition type internal combustion engine which can perform active ignition to ignite, and which is accompanied by an EGR device which recirculates a part of exhaust gas and mixes it with intake air,
Compared to the situation where EGR is not performed without active ignition or the amount of EGR gas is smaller, the fuel consumption that can be reduced by increasing the amount of EGR gas by performing active ignition, and the power consumed for active ignition A control device for an internal combustion engine, which calculates a fuel consumption amount required to cover the above and performs active ignition on condition that the former exceeds the latter. Plasma is generated in the combustion chamber by mixing the electric field generated in the combustion chamber via the antenna facing the combustion chamber of the cylinder and the spark discharge generated between the center electrode and the ground electrode of the spark plug, and mixing A spark ignition type internal combustion engine which can perform active ignition to ignite, and which is accompanied by an EGR device which recirculates a part of exhaust gas and mixes it with intake air,
A control device for an internal combustion engine, wherein active ignition is performed on condition that the amount of EGR gas is larger than a limit amount that does not destabilize fuel combustion in a cylinder.

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