JP2010096163A - Method for controlling spark-ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain generation of troubles of oxidization of the ignition plug and the surface of the combustion chamber by ozone generated by the reaction of the oxygen in the air and the plasma or the radicals produced by the reaction with the ozone in a spark-ignition internal combustion engine for igniting a fuel/air mixture by reacting spark discharge by an ignition plug and plasma produced in a combustion chamber. <P>SOLUTION: During fuel supply in a vehicle-running operation, a fuel/air mixture is ignited by reacting spark discharge by an ignition plug and plasma produced in a combustion chamber. While the fuel supply is interrupted, the plasma production is stopped. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control method for a spark ignition type internal combustion engine that ignites an air-fuel mixture by reacting spark discharge caused by an ignition plug with plasma generated in a combustion chamber.

  Conventionally, in a spark ignition internal combustion engine mounted on a vehicle, particularly an automobile, a spark discharge between a center electrode of a spark plug and a ground electrode ignites an air-fuel mixture in a combustion chamber at each ignition timing. . For example, in an internal combustion engine of the type in which fuel is directly injected into a cylinder by ignition by such a spark plug, it is rare that ignition does not occur unless the injected fuel is distributed to the spark discharge positions of the spark plug.

Therefore, in such an internal combustion engine, a plasma atmosphere is generated in the discharge region of the spark plug, a spark discharge is performed in the plasma atmosphere, and the spark discharge and the plasma are reacted, thereby comparing with the conventional one. A configuration is known in which an air-fuel mixture in a combustion chamber is ignited steadily without applying a high voltage so that combustion is stably performed (see, for example, Patent Document 1).
JP 2007-32349 A

  By the way, when a plasma atmosphere is generated in the combustion chamber during fuel cut, electrons in the plasma atmosphere collide with oxygen molecules in the air, dissociating oxygen molecules to generate oxygen atoms, and these oxygen atoms are generated in the air. By combining with oxygen molecules, ozone is generated in the combustion chamber. Then, the trouble which the spark plug and the combustion chamber surface oxidize by the generated ozone and the radical generated by the reaction with ozone occurs.

  The present invention aims to solve such problems.

  One of the control methods of the spark ignition type internal combustion engine of the present invention is to generate spark discharge by the spark plug and the combustion chamber while supplying fuel while the vehicle is running in order to solve the above-described problems. It is characterized by igniting the air-fuel mixture by reacting with the plasma and generating the plasma while the fuel supply is interrupted while the vehicle is running.

  If this is the case, if the vehicle is decelerated while the vehicle is running, the generation of plasma is stopped while the fuel supply is interrupted, so that electrons in the plasma atmosphere collide with oxygen molecules. The dissociation of oxygen molecules can be suppressed, and therefore generation of ozone in the combustion chamber can be suppressed.

  Another method of controlling a spark ignition internal combustion engine according to the present invention is to solve the above-described problems by spark discharge and combustion by a spark plug while fuel is being supplied while the vehicle is running. After deciding to suspend the fuel supply by reacting with the plasma generated in the room and igniting the gas mixture, the spark discharge and plasma generated by the spark plug are reduced while the fuel supply amount is reduced until a predetermined time has elapsed. And the gas mixture is ignited. When a predetermined time elapses, the fuel supply is interrupted and the plasma generation is stopped.

  Even in such a case, when deceleration is performed while the vehicle is running, the generation of plasma is stopped while the fuel supply is interrupted, so that electrons in the plasma atmosphere collide with oxygen molecules. The dissociation of oxygen molecules due to the ozone can be suppressed, and therefore generation of ozone in the combustion chamber can be suppressed. Moreover, since the fuel supply is not interrupted until a predetermined time has elapsed, plasma is generated to stabilize combustion, thereby reducing the misfire limit to a region where a shock due to a decrease in output torque does not occur even if fuel cut is performed. Therefore, it is possible to prevent the engine misfire and the occurrence of the shock at the same time.

  According to the present invention, dissociation of oxygen molecules due to collision of electrons and oxygen molecules in the plasma atmosphere can be suppressed by stopping the generation of plasma while the supply of fuel is interrupted. That is, generation of ozone in the combustion chamber can be suppressed. Therefore, the effect which can suppress generation | occurrence | production of the malfunction which the spark plug and the combustion chamber surface oxidize by the generated ozone and the radical produced | generated by reaction with ozone is acquired.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

An engine 100 schematically showing the configuration of one cylinder in FIG. 1 is a three-cylinder for an automobile. The intake system 1 of the engine 100 is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown), and a surge tank 3 is provided downstream of the throttle valve 2. A fuel injection valve 5 is further provided in the vicinity of the end on the cylinder head 4 side where the surge tank 3 communicates, and the fuel injection valve 5 is controlled by the electronic control unit 6. An ignition plug 8 and an antenna 9 for generating plasma are attached to the ceiling portion of the combustion chamber 7. The antenna 9 in this embodiment is a horn type antenna and is attached to a position near the spark plug 8 on the ceiling of the combustion chamber 7. An ignition coil 10 that is integrally provided with an igniter is attached to the ignition plug 8 in a replaceable manner. The antenna 9 has a horn shape, and a tip portion facing the combustion chamber 7 is closed by a dielectric 27 such as ceramics, and is connected to a high voltage AC generator 11 via a waveguide (not shown). Yes. In the exhaust system 12, a three-way catalyst (hereinafter referred to as catalyst 13) is disposed in a pipe line leading to a muffler (not shown), and an O ₂ sensor 14 is attached upstream thereof.

  The high-voltage AC generator 11 includes a magnetron 15 and a control circuit 16 that controls the magnetron 15. The microwave output from the magnetron 15 is applied to the antenna 9 through a waveguide. Further, the control circuit 16 is configured to receive the high-voltage AC generation signal n output from the electronic control unit 6, and the control circuit 16 is configured to output the microtron output from the magnetron 15 based on the input high-voltage AC generation signal n. It controls the wave output timing and output power.

  The electronic control device 6 is mainly configured by a microcomputer system including a central processing unit 18, a storage device 19, an input interface 20, and an output interface 21. The central processing unit 18 controls the operation of the engine 100 by executing a program described later stored in the storage device 19.

Information necessary for controlling the operation of the engine 100 is input to the central processing unit 18 via the input interface 20, and the central processing unit 18 sends a control signal to the fuel via the output interface 21. Output to the injection valve 5 or the like. Specifically, the input interface 20 includes an intake pressure signal a output from an intake pressure sensor 22 for detecting the pressure of intake air in the surge tank 3, and a rotation speed sensor 23 for detecting the engine speed. , An engine speed signal b output from the idle switch 24 for detecting the open / closed state of the throttle valve 2, and a water temperature signal output from the water temperature sensor 25 for detecting the cooling water temperature of the engine 100. d, an intake air temperature signal e output from the intake air temperature sensor 26 for detecting the temperature of fresh air taken in by the engine 100, and an oxygen concentration in the exhaust gas discharged from the combustion chamber 7 through the exhaust valve. For example, a voltage signal f output from the O ₂ sensor 14 and a vehicle speed signal g output from the vehicle speed sensor 28 for detecting the vehicle speed are input. On the other hand, the output interface 21 outputs a fuel injection signal p to the fuel injection valve 5, an ignition signal m to the igniter, a high-voltage AC generation signal n to the high-voltage AC generator 11, and the like. Yes.

  The storage device 19 of the electronic control unit 6 uses the intake pressure signal a output from the intake pressure sensor 22 and the rotation speed signal b output from the rotation speed sensor 23 as main information, and depends on the operating state of the engine 100. The basic injection time is corrected by various correction coefficients determined in accordance with the above, and the opening time of the fuel injection valve 5, that is, the final energization time of the injector is determined. A program for injecting the corresponding fuel from the fuel injection valve 5 to the intake system 1 is incorporated.

  In the engine 100, in the normal operation state after warming up, the microwave generated by the high-voltage AC generator 11 is radiated from the antenna 9 into the combustion chamber 7 in accordance with the output timing controlled by the control circuit 16, The plasma generated thereby reacts with the spark discharge generated by the spark plug 8 to ignite the air-fuel mixture. When plasma is generated, microwaves are applied to the antenna 9, whereby a high-frequency electric field is formed in the combustion chamber 7 in a direction perpendicular to the spark discharge by the spark plug 8.

  Thus, upon ignition, a spark discharge is generated in the spark plug 8 by the ignition coil 10, and a high-frequency electric field is generated by microwaves almost simultaneously with or immediately after the spark discharge to generate plasma, thereby generating a combustion chamber. 7 is a mechanism for rapidly burning the air-fuel mixture in the fuel cell 7.

  Specifically, the spark discharge by the spark plug 8 becomes plasma in a high-frequency electric field, and the flame becomes large.

  This is because the flow of electrons due to the spark discharge and the ions and radicals generated by the spark discharge oscillate and meander due to the influence of the high-frequency electric field, resulting in a longer path length and the number of collisions with surrounding water and nitrogen molecules. This is due to a dramatic 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 ionized, in other words, a plasma state. The flame will increase dramatically.

  As a result, the air-fuel mixture is ignited by the spark discharge increased by reacting with the high-frequency electric field, so that the ignition region is expanded and the two-dimensional ignition of only the spark plug 8 is changed to three-dimensional ignition. Therefore, the initial combustion is stabilized, the combustion rapidly propagates into the combustion chamber 7 with the increase of the radicals described above, and the combustion expands at a high combustion rate.

  Thus, in the present embodiment, while fuel is being supplied to the storage device 19 of the electronic control device 6 while the vehicle is running, spark discharge by the spark plug 8 and microwaves radiated from the antenna 9 enter the combustion chamber. If the conditions for deciding whether to interrupt the fuel supply by reacting with the generated plasma and igniting the air-fuel mixture, immediately stop the fuel supply and stop the plasma generation. It also has a built-in program for performing control.

  Hereinafter, a schematic procedure for controlling the internal combustion engine 100 will be described with reference to the flowchart shown in FIG.

  First, in step S1, it is determined whether or not a fuel cut condition is satisfied. Specifically, the IDL signal c indicating that the throttle valve 2 is fully closed, that is, the idle switch 24 is ON, is output from the idle switch 24, and the vehicle speed signal g output from the vehicle speed sensor 28 is The indicated vehicle speed is equal to or higher than the predetermined vehicle speed, the water temperature signal d output from the water temperature sensor 25 indicates that the vehicle is warming up, and the engine speed indicated by the rotational speed signal b from the rotational speed sensor 23 is equal to or higher than the predetermined rotational speed. If it is, it is determined that the fuel cut condition is satisfied. If the fuel cut condition is satisfied, the process proceeds to step S2. If the fuel cut condition is not satisfied, this program is terminated.

  In step S2, a fuel cut is performed. Thereafter, the process proceeds to step S3.

  In step S3, control for stopping microwave irradiation for generating plasma is performed. That is, the output of the high voltage AC generation signal n to the high voltage AC generator 11 is stopped. And this program is complete | finished.

  That is, when the fuel cut condition is satisfied, the fuel supply is interrupted and plasma generation is stopped by immediately performing the control of steps S 1 → S 2 → S 3 immediately.

  As described above, if the control method of the engine 100 according to the present embodiment is employed, the generation of plasma is stopped while the fuel supply is interrupted, so that electrons in the plasma atmosphere collide with oxygen molecules. This can suppress dissociation of oxygen molecules. That is, generation of ozone in the combustion chamber can be suppressed. Therefore, the effect which can suppress generation | occurrence | production of the malfunction which the surface of the spark plug 8 or the combustion chamber 7 oxidizes by the generated ozone and the radical produced | generated by reaction with ozone is acquired.

  Next, a second embodiment of the present invention will be described with reference to the drawings. In addition, the same name and code | symbol are attached | subjected to the site | part corresponding to the thing in 1st embodiment mentioned above.

  Since the engine 100 according to the present embodiment has the same configuration as the engine 100 according to the first embodiment, detailed description of the configuration is omitted.

  Therefore, in this embodiment, the storage device 19 of the electronic control device 6 replaces the program according to the first embodiment with a spark discharge by the spark plug 8 while fuel is being supplied while the vehicle is running. And the plasma generated in the combustion chamber by the microwaves radiated from the antenna 9 are ignited to ignite the air-fuel mixture and the fuel supply is interrupted, and then the fuel supply is continued until a predetermined time T has elapsed. Built-in program for controlling the spark discharge and plasma to react while reducing the amount to ignite the air-fuel mixture and to interrupt the supply of fuel and stop the generation of plasma when a predetermined time T has elapsed. . After the condition for deciding to interrupt the fuel supply is satisfied during the predetermined time T, an operation of gradually decreasing the fuel supply amount while generating plasma is performed. The time required to reach an area where no shock due to the reduction occurs is obtained in advance based on experiments, and is stored in a predetermined area of the storage device 19.

  Hereinafter, a schematic procedure for controlling the internal combustion engine 100 will be described with reference to a flowchart shown in FIG.

  First, in step S11, it is determined whether or not a fuel cut condition is satisfied. Specifically, the IDL signal c indicating that the throttle valve 2 is fully closed, that is, the idle switch 24 is ON, is output from the idle switch 24, and the vehicle speed signal g output from the vehicle speed sensor 28 is The indicated vehicle speed is equal to or higher than the predetermined vehicle speed, the water temperature signal d output from the water temperature sensor 25 indicates that the vehicle is warming up, and the engine speed indicated by the rotational speed signal b from the rotational speed sensor 23 is equal to or higher than the predetermined rotational speed. If it is, it is determined that the fuel cut condition is satisfied. If the fuel cut condition is satisfied, the process proceeds to step S12. If the fuel cut condition is not satisfied, this program is terminated.

  In step S12, the predetermined time T is determined using the engine speed calculated from the speed signal b from the speed sensor 23 as a parameter. Next, the process proceeds to step S13.

  In step S13, it is determined whether or not an elapsed time t after the fuel cut condition is satisfied is less than a predetermined time T. When the elapsed time t after the fuel cut condition is satisfied is less than the predetermined time T, the process proceeds to step S14. On the other hand, when the elapsed time t after the fuel cut condition is satisfied is equal to or longer than the predetermined time T, the process proceeds to step S16.

  In step S14, control is performed to decrease the fuel supply amount by a predetermined amount. That is, the fuel injection signal p corresponding to the fuel supply amount after being reduced by a predetermined amount is output to the fuel injection valve 5. Thereafter, the process proceeds to step S15.

  In step S15, control is performed to irradiate microwaves to generate plasma. That is, the high-voltage AC generation signal n is output to the high-voltage AC generator 11. Here, in the present embodiment, in order to make the combustion more stable in accordance with the operating state of the engine 100, more plasma is generated than before the control by this program is started, that is, the output of the high-pressure AC generator 11 is increased. I have to. Then, the process returns to step S13.

  In step S16, fuel cut is performed. Thereafter, the process proceeds to step S17.

  In step S17, control is performed to stop microwave irradiation for generating plasma. That is, the output of the high voltage AC generation signal n to the high voltage AC generator 11 is stopped. And this program is complete | finished.

  That is, when the fuel cut condition is satisfied, the control of steps S11 to S12 is sequentially performed in order to determine the predetermined time T based on the engine speed.

  Next, when the elapsed time t after the fuel cut condition is satisfied is less than the predetermined time T, the control of steps S13 → S14 → S15 is sequentially performed. That is, plasma is continuously generated while the fuel supply amount is gradually decreased. Thereafter, the process returns to step S13.

  On the other hand, when the elapsed time t after the fuel cut condition is satisfied reaches the predetermined time T, the control of steps S13 → S16 → S17 is sequentially performed. That is, fuel supply and plasma generation are stopped.

  As described above, if the method for controlling the engine 100 according to the present embodiment is employed, the generation of plasma is stopped while the fuel supply is interrupted, as in the method for controlling the engine 100 according to the first embodiment. Thus, dissociation of oxygen molecules due to collision between electrons and oxygen molecules in the plasma atmosphere can be suppressed. That is, generation of ozone in the combustion chamber can be suppressed. Therefore, the effect which can suppress generation | occurrence | production of the malfunction which the surface of the ignition plug 8 or the combustion chamber 7 oxidizes by the generated ozone and the radical produced | generated by reaction with ozone is acquired similarly.

  In addition, according to the control method of the engine 100 according to the present embodiment, plasma is generated while reducing the fuel injection amount until the elapsed time t after the fuel cut condition is satisfied reaches the predetermined time T. By igniting and stabilizing the combustion, the misfire limit can be lowered to a region where no shock is generated due to a decrease in the output torque, and therefore it is possible to simultaneously prevent the engine misfire and the occurrence of the shock. An effect is also obtained.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described second embodiment of the present invention, after the fuel cut condition is satisfied, the predetermined time until the fuel supply is stopped is a parameter other than the engine speed, such as an ISC amount, a gear reduction ratio, It may be determined based on the opening degree of the throttle valve immediately before the throttle valve is fully closed.

  In addition to the magnetron as described above, the high frequency generation source may be a traveling wave tube or the like, and may further include a semiconductor microwave oscillation circuit.

  In addition, although the beam type antenna has been described in the above-described embodiments, a monopole antenna may be used.

  Furthermore, the center electrode of the spark plug 8 may function as an antenna to form a high frequency power feeding unit. In this case, if the high frequency is continuously applied to the center electrode at a constant voltage, the temperature of the center electrode rises excessively, so the high frequency voltage is set to be lower than the upper limit temperature set based on the heat resistance temperature of the center electrode. It is something to control.

  In addition, various changes may be made without departing from the spirit of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows schematic structure of 1st embodiment of this invention. The flowchart which shows the outline of the control procedure of the embodiment. The flowchart which shows the outline of the control procedure of 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Engine 5 ... Fuel injection valve 6 ... Control apparatus 8 ... Spark plug 9 ... Antenna 15 ... Magnetron

Claims (2)

While the fuel is being supplied while the vehicle is running, the spark discharge by the spark plug and the plasma generated in the combustion chamber react to ignite the mixture,
A control method for a spark ignition type internal combustion engine in which plasma generation is stopped while fuel supply is interrupted while a vehicle is running. While the fuel is being supplied while the vehicle is running, the spark discharge by the spark plug and the plasma generated in the combustion chamber react to ignite the mixture,
After deciding to interrupt the fuel supply, the spark mixture by the spark plug reacts with the plasma while reducing the fuel supply amount until a predetermined time elapses, and the mixture is ignited.
A control method for a spark ignition internal combustion engine that interrupts the supply of fuel and stops the generation of plasma when a predetermined time has elapsed.

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