JP2008101585A - Control device and method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress change in combustion status of an internal combustion engine, when an electrode gap of an ignition plug is enlarged. <P>SOLUTION: A control device for an internal combustion engine controls an internal combustion engine 1, in which an ignition plug 11 including a center electrode and a ground electrode spaced from each other and opposed to each other is disposed on a cylinder. The control device for an internal combustion engine comprises a distance specifying means 30 specifying a distance between the center electrode and ground electrode, and a parameter changing means 30 making a change of a predetermined parameter defining the combustion status of the internal combustion engine, depending on the specified distance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device and method for an internal combustion engine including, for example, a vehicle ignition plug.

  In this type of control device, a high voltage is applied between the center electrode and the ground electrode of the spark plug, and spark discharge is performed between the two electrodes to ignite the air-fuel mixture. For this reason, both electrodes wear with use, and the distance (henceforth an electrode gap) between both electrodes expands.

  For example, Patent Document 1 discloses an internal combustion engine that calculates an energization time of an ignition coil based on the rotation speed of an internal combustion engine and a battery voltage, and corrects the calculated energization time based on an electrode gap of an ignition plug. A control device is described.

  Patent Document 2 describes a technique for ensuring ignitability and reducing electrode wear by appropriately defining the electrode shape of the spark plug.

  In the spark plug, it is known that the discharge voltage between the electrodes and the electrode gap have a certain relationship (see Patent Documents 1 and 3).

JP-A-6-129333 JP-A-10-189213 JP 2002-319469 A

  However, according to the background art described above, the combustion state such as the combustion speed and the combustion temperature of the air-fuel mixture is not considered. For this reason, when the electrode gap is enlarged, only the energization time is changed, or the energization time is changed so as to minimize ignition energy. There is a technical problem that the combustion state changes such as high temperature.

  The present invention has been made in view of the above problems, for example, and provides a control device and method for an internal combustion engine that suppresses changes in the combustion state of the internal combustion engine when the electrode gap of the spark plug is widened. Is an issue.

  In order to solve the above-described problems, the control device for an internal combustion engine of the present invention is a control device that controls an internal combustion engine that includes a spark plug having a center electrode and a ground electrode that are spaced apart from each other and that are opposed to each other. Distance specifying means for specifying the distance between the electrode and the ground electrode, and parameter changing means for changing a predetermined parameter that defines the combustion state of the internal combustion engine according to the specified distance.

  According to the control device of the present invention, the control device controls the combustion state of the internal combustion engine when the internal combustion engine which is an engine in a vehicle such as an automobile is operated. Specifically, for example, the air-fuel ratio of the air-fuel mixture and the ignition timing of the spark plug are controlled to change the combustion temperature, the combustion speed, and the like. At this time, the distance specifying means specifies the distance between the center electrode and the ground electrode of the spark plug, that is, the electrode gap based on the discharge voltage, the number of times of ignition of the spark plug, and the like. In the present invention, “specifying the distance” includes a case where the distance is calculated or calculated, estimated, estimated or predicted, or directly or indirectly measured. Further, “specifying the distance” includes not only specifying the distance directly, but also specifying the amount of wear on the surface of the spark plug that has a one-to-one correspondence with the distance. That is, the “distance specifying means for specifying the distance between the center electrode and the ground electrode” means “the amount of wear or the worn distance in the opposed surface portions of the center electrode and the ground electrode in the spark plug having a predetermined shape”. In the case of “distance specifying means for specifying”.

  According to the inventor's research, in general, in an internal combustion engine, an air-fuel mixture is ignited by a spark discharge between both electrodes of a spark plug, and as a result of the electrode being worn by the impact of the spark discharge, the electrode gap is expanded. . Therefore, if any countermeasure is not taken, the ignitability of the spark plug improves as the electrode gap increases. For this reason, the time until the flame nuclei generated between the two electrodes supply the heat energy necessary for causing the combustion reaction in the air-fuel mixture is shortened. Therefore, if the air-fuel ratio, ignition timing, etc. of the air-fuel mixture are not changed, the combustion state changes, for example, the combustion temperature becomes high, nitrogen in the air is easily oxidized, and NOx emissions increase. End up.

  However, according to the present invention, the combustion state of a predetermined type of internal combustion engine such as the air-fuel ratio of the air-fuel mixture and the ignition timing of the spark plug is determined by the parameter changing means according to the electrode gap specified by the distance specifying means as described above. Changes are made to predetermined parameters that define Here, the “predetermined parameter” according to the present invention is typically such an air-fuel ratio or ignition timing, but more generally means any physical quantity or parameter related to the combustion state of the internal combustion engine. At this time, the parameter to be changed may be one type or a plurality of types. Thereby, the change of combustion temperature can be suppressed and the change amount of NOx emission amount can be suppressed.

  Therefore, even if the electrode is worn due to the impact of spark discharge between both electrodes of the spark plug and the electrode gap is widened, the change of the ignitability in the spark plug can be suppressed by changing the parameter by the parameter changing means. Is possible. Specifically, it is possible to effectively prevent or prevent the flame nuclei generated between the two electrodes from being easily hit by the electrodes, or the heat of the flame nuclei from being taken away by the electrodes, that is, reducing the flame extinguishing effect. For this reason, it is possible to prevent the time until the flame kernel supplies heat energy necessary for causing a combustion reaction to the air-fuel mixture, that is, the time until it grows to a certain size. The amount of wear of both electrodes due to this spark discharge can specifically be, for example, several millimeters of commas, but the change in ignitability due to such amount of wear can be effectively prevented or prevented. Thus, even when a voltage is applied between the electrodes of the spark plug at a predetermined ignition timing, it is possible to prevent the time until the combustion reaction of the air-fuel mixture occurs from being shortened. Therefore, for example, it is possible to prevent a situation in which nitrogen in the air is easily oxidized due to the high combustion temperature, thereby increasing the NOx emission amount. Since the upper limit of the NOx emission amount is determined by law, such prevention of the increase in NOx emission amount is extremely desirable in practice.

  As a result of the above, according to the control apparatus for an internal combustion engine of the present invention, when the electrode gap of the spark plug is expanded by changing the parameter that defines the combustion state according to the specified distance, the combustion state Can be suppressed.

  In one aspect of the control apparatus for an internal combustion engine of the present invention, the parameter changing means changes the air-fuel ratio of the internal combustion engine as the parameter.

  According to this aspect, the parameter changing means changes the air-fuel ratio as a parameter that defines the combustion state of the internal combustion engine. Specifically, the air-fuel ratio is controlled to become lean as the electrode gap increases. The leaner the air-fuel ratio, the less the unburned air-fuel mixture adjacent to the flame kernel, and the more difficult the combustion reaction occurs, or the more difficult the combustion reaction occurs. Thereby, the change of a combustion state can be suppressed. Further, as the air-fuel ratio becomes leaner, the combustion temperature of the air-fuel mixture increases, but the amount of NOx generated can be reduced and the amount of NOx emission can be reduced.

  In another aspect of the control apparatus for an internal combustion engine of the present invention, the parameter changing means controls an ignition timing of the spark plug as the parameter.

  According to this aspect, the parameter changing means controls the ignition timing of the spark plug as a parameter that defines the combustion state of the internal combustion engine. Specifically, the ignition timing is controlled to be retarded as the electrode gap increases. When the ignition timing is retarded, for example, the pressure in the cylinder decreases, so the combustion speed decreases. Thereby, the change of a combustion state can be suppressed. Further, as the ignition timing is retarded, the combustion temperature of the air-fuel mixture in the cylinder of the internal combustion engine decreases, the amount of NOx generated decreases, and the NOx emission amount can be reduced.

  According to another aspect of the control apparatus for an internal combustion engine of the present invention, the distance specifying means includes an ignition frequency detecting means for detecting the ignition frequency of the spark plug, and the distance based on the detected ignition frequency. Calculating means for calculating.

  According to this aspect, the ignition frequency detecting means detects the ignition frequency of the spark plug. Here, “detecting the number of ignitions” according to the present invention refers to indirectly detecting other times based on other parameters that change according to the number of ignitions or regulate the number of ignitions, in addition to directly detecting the number of ignitions. This includes the case of detection. Specifically, for example, the ignition number detection means detects the number of revolutions of the internal combustion engine from the top dead center pulse of the piston, and detects or calculates the number of ignitions based on the detected number of revolutions.

  The computing means calculates the distance between both electrodes of the spark plug based on the detected number of ignitions. Each time a voltage is applied, i.e., ignited, the spark plug electrode is worn by the impact of a spark discharge. For this reason, a certain relationship is established between the number of ignitions of the spark plug and the electrode gap or the amount of wear. Therefore, the calculation means calculates or specifies the electrode gap by using a predetermined calculation formula or a map that defines the relationship between the number of ignitions and the electrode gap, for example. In addition, what is necessary is just to comprise such a map by measuring the frequency | count of ignition and an electrode gap by experiment, and specifying both relationship, for example. Or what is necessary is just to comprise by simulation etc.

  As a result, according to this aspect, the distance between the center electrode and the ground electrode of the spark plug can be calculated or specified relatively easily.

  According to another aspect of the control device for an internal combustion engine of the present invention, the distance specifying means includes an internal pressure detecting means for detecting the pressure in the cylinder, and a voltage for detecting a voltage applied between the center electrode and the ground electrode. And detecting means, and calculating means for calculating the distance of the spark plug based on the detected voltage and the detected pressure.

  According to this aspect, the voltage detection means which is a voltmeter, for example, detects the voltage applied between both electrodes of the spark plug. When the voltage exceeds a predetermined threshold, that is, a discharge start voltage, a spark discharge occurs between both electrodes. The voltage detection means detects a discharge start voltage corresponding to the actual discharge voltage of the spark discharge generated between both electrodes.

  For example, an internal pressure detecting means, which is an internal pressure sensor, detects the pressure in the cylinder when spark discharge occurs, that is, during ignition. The discharge start voltage is mainly determined by the distance between the electrodes, that is, the electrode gap, and the pressure in the cylinder. Therefore, the electrode gap can be specified only by detecting the discharge start voltage and pressure.

  Note that “detecting the pressure in the cylinder” includes not only detecting the pressure directly but also detecting it indirectly based on other parameters that change or regulate the pressure. . Similarly, “detecting a voltage” includes not only detecting the voltage directly but also detecting it indirectly based on other parameters that change according to the voltage or define the voltage.

  The calculation means calculates the distance between both electrodes of the spark plug based on the detected voltage and the detected pressure, for example, by a predetermined calculation formula.

  As a result, according to this aspect, the distance between the center electrode and the ground electrode of the spark plug can be calculated or specified relatively easily. In addition, even if the spark plug is replaced, there is no burden for the operator to perform a special operation, which is very advantageous in practice.

  In another aspect of the control device for an internal combustion engine of the present invention, the parameter changing means changes the predetermined parameter so that the change in the combustion state due to the change in the specified distance becomes small.

  According to this aspect, the parameter changing means, for example, the air-fuel ratio of the air-fuel mixture is reduced so that the change in the distance between both electrodes of the specified spark plug, that is, the change in the combustion state due to the change in the electrode gap becomes small. And changes to predetermined parameters such as spark plug ignition timing. Thereby, when the electrode gap of a spark plug expands, the change of a combustion state can be suppressed.

  In order to solve the above-described problem, a control method for an internal combustion engine of the present invention is a control method for controlling an internal combustion engine that includes a spark plug having a center electrode and a ground electrode that are spaced apart from each other and that are opposed to each other. A distance specifying step of specifying a distance between the electrode and the ground electrode, and a parameter changing step of changing a predetermined parameter defining a combustion state of the internal combustion engine according to the specified distance.

  According to the control method for an internal combustion engine of the present invention, the change in the combustion state can be suppressed when the electrode gap of the spark plug is enlarged, similarly to the control device for the internal combustion engine of the present invention described above.

  The internal combustion engine control method of the present invention can also adopt various aspects similar to the various aspects of the above-described internal combustion engine control apparatus of the present invention.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
A first embodiment of the control device for an internal combustion engine of the present invention will be described with reference to FIGS.

  First, the configuration of the control device for an internal combustion engine according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an internal combustion engine provided with a control device for an internal combustion engine according to the present embodiment and its peripheral devices.

  In FIG. 1, the control device for the internal combustion engine specifies the distance between the center electrode and the ground electrode of the spark plug 11, and sets a predetermined type of parameter that defines the combustion state of the internal combustion engine 1 according to the specified distance. An ECU (Electronic Control Unit) 30 to be changed is provided. Here, the ECU 30 according to the present embodiment is an example of the “distance identifying unit” and the “parameter changing unit” according to the present invention.

  Note that the ECU 30 is configured to perform various electronic controls in the internal combustion engine 1 or in the vehicle on which the internal combustion engine 1 is mounted, in addition to the control related to the ignition. In other words, in this embodiment, a part of the ECU 30 for various electronic controls is used as a part of the control device for the internal combustion engine.

  The ECU 30 includes a CPU (Central Processing Unit) 301, a memory 302 that is a nonvolatile memory such as a backup ROM and a flash memory, and an input / output circuit 303 that inputs and outputs signals.

  The control device for the internal combustion engine further detects an ignition coil 21 for applying a voltage to the spark plug 11, a voltage sensor 22 for detecting a voltage applied between the center electrode and the ground electrode of the spark plug 11, and a pressure in the cylinder 12. And a top dead center pulse sensor 24 for detecting a top dead center pulse generated when the piston 18 reaches the top dead center. Here, the voltage sensor 22 and the internal pressure sensor 23 according to the present embodiment are examples of the “voltage detection unit” and the “internal pressure detection unit” according to the present invention, respectively.

  The cylinder 12 of the internal combustion engine 1 has an intake pipe 13 provided with an air flow meter 15 for detecting the amount of air flowing in, a throttle valve 16 for adjusting the amount of air supplied, a fuel injection valve 17 for supplying fuel, and the like. It is connected. The air-fuel mixture introduced into the cylinder 12 through the intake pipe 13 is applied with a high voltage between the center electrode and the ground electrode of the spark plug 11 by the ignition coil 21, and spark discharge is generated between both electrodes. Is ignited by The exhaust gas after combustion is discharged through the exhaust pipe 14.

  Although the internal combustion engine 1 includes a plurality of cylinders, FIG. 1 shows one cylinder 12 among the plurality of cylinders for convenience of explanation.

  The ECU 30 as an example of the “ignition frequency detection means” according to the present invention accumulates the number of top dead center pulses detected by the top dead center pulse sensor 24, and ignites the ignition plug 11 according to the accumulated number. The number of times is detected or calculated. The ECU 30 as an example of the “calculation unit” according to the present invention calculates the electrode gap of the spark plug 11 based on the detected number of ignitions.

  Next, a method for calculating the electrode gap of the spark plug 11 in the ECU 30 will be described with reference to FIG. FIG. 2 is an example of a map that defines the relationship between the number of ignitions and the amount of gap wear. For example, such a map may be configured by measuring the number of ignitions and the amount of gap wear by experiment. Or what is necessary is just to comprise by simulation etc. Here, the “gap wear amount” refers to the amount of wear of the center electrode and the ground electrode of the spark plug 11 due to the impact of the spark discharge generated between both electrodes. Refers to volume.

  The CPU 301 of the ECU 30 integrates the number of top dead center pulses detected by the top dead center pulse sensor 24. The internal combustion engine 1 has a plurality of cylinders, and a top dead center pulse is detected for each cylinder. Therefore, since the accumulated number of top dead center pulses is a sum value for all the cylinders, the CPU 301 calculates the number of ignitions of the spark plug 11 from the ignition cycle of the cylinders 12, for example.

  The CPU 301 specifies the gap wear amount from a map as shown in FIG. 2 stored in the memory 302 based on the number of ignitions of the spark plug 11. For example, when the gap wear amount is represented by the volume of the worn electrode, the CPU 301 determines the electrode gap based on the specified gap wear amount by, for example, a predetermined arithmetic expression that takes into account the electrode shape and the like. calculate.

  In the map shown in FIG. 2, the vertical axis may be an electrode gap. In this case, since the process of calculating the electrode gap from the gap wear amount can be omitted by a predetermined arithmetic expression or the like, the processing time can be shortened. In FIG. 2, the number of ignitions and the amount of gap wear are shown as being in a simple proportional relationship (that is, a linear function relationship or a relationship approximate thereto) for convenience, but depending on the electrode shape of the spark plug. May not be such a proportional relationship. Even in such a case, as long as there is a certain correspondence between the two (for example, a quadratic function or a high-order function, or a relationship approximate thereto), the map can be used to calculate the gap wear amount using the same method. It is possible to determine the electrode gap.

  Next, a method of controlling a predetermined parameter that defines the combustion state of the internal combustion engine 1 in accordance with the calculated electrode gap in the ECU 30 will be described with reference to FIGS. FIG. 3 is an example of a map that defines the relationship between the gap wear amount and the lean increase amount. Here, the “lean increase amount” is a coefficient representing how much the air-fuel ratio is made lean. FIG. 4 is an example of a map that defines the relationship between the gap wear amount and the ignition timing retardation amount. Here, in this embodiment, the amount of retardation is set to a negative value for convenience.

  Such a map is obtained by measuring the combustion temperature, NOx emission amount, etc. when changing the lean increase amount or the ignition timing retard amount by using spark plugs of various wear amounts by experiments, for example, and gap wear. The optimum lean increase amount or ignition timing retardation amount may be specified for the amount. In the maps shown in FIGS. 3 and 4, the horizontal axis may be an electrode gap. If the physical quantity or parameter on the horizontal axis of the map as shown in FIGS. 3 and 4 is the same as the physical quantity or parameter on the vertical axis of the map as shown in FIG. 2, processing can be performed smoothly.

  First, the CPU 301 of the ECU 30 determines whether or not the operation in which the air-fuel ratio in the internal combustion engine 1 is lean (hereinafter referred to as lean operation). When it is not the lean operation, the ECU 30 does not change the parameter that defines the combustion state of the internal combustion engine 1, and maintains the operation at a predetermined basic air-fuel ratio or basic ignition timing, for example. Here, the basic air-fuel ratio is, for example, the stoichiometric air-fuel ratio, and the basic ignition timing is an appropriate timing according to the internal combustion engine 1, for example, a timing advanced by 5 degrees. The basic air-fuel ratio and the basic ignition timing may be fixed values or may be variable according to the load of the internal combustion engine 1 and the coolant temperature.

  In the case of the lean operation, the CPU 301 specifies the lean increase amount and the ignition timing retard amount according to the gap wear amount from the maps as shown in FIGS. 3 and 4 stored in the memory 302. The CPU 301 changes the air-fuel ratio and controls the ignition timing based on the specified lean increase amount and ignition timing retardation amount.

  The air-fuel ratio is changed by adjusting the throttle valve 16 or the air-fuel ratio by multiplying the air-fuel ratio set corresponding to the lean operation when there is no wear of the electrode of the spark plug 11 by the obtained lean increase amount. The fuel injection valve 17 or both are controlled. Here, the air-fuel ratio that is set corresponding to the lean operation when there is no electrode wear may be obtained by multiplying the basic air-fuel ratio by a lean set value that becomes the target air-fuel ratio, for example. Specifically, for example, when the basic air-fuel ratio is 14.7 and the target air-fuel ratio is 21, the lean set value may be multiplied by 1.43. The ignition timing is controlled by controlling the ignition coil 21 so that ignition is performed at a timing obtained by adding an ignition timing retard amount to the basic ignition timing.

  It should be noted that the control of the parameter that defines the combustion state of the internal combustion engine 1 may be performed only in one of the air-fuel ratio and the ignition timing, and may be performed in accordance with the state and performance of the internal combustion engine 1, such as temperature and load.

  Next, a combustion control process executed by the ECU 30 in the control apparatus for an internal combustion engine configured as described above will be described with reference to a flowchart of FIG. This combustion control process is executed mainly every few seconds to every few seconds, for example, regularly or irregularly while the vehicle is traveling.

  First, for example, the number of ignitions of the spark plug 11 is detected based on the top dead center pulse detected by the top dead center pulse sensor 24 (step S101). Next, the gap wear amount of the spark plug 11 is calculated based on the detected number of ignitions (step S102). Subsequently, it is determined whether or not the lean operation is performed (step S103). If it is not the lean operation (step S103: No), the operation at the predetermined basic air-fuel ratio (step S104) and the basic ignition timing (step S105) is maintained, and the process is temporarily ended.

  If it is a lean operation (step S103: Yes), a lean increase amount corresponding to the gap wear amount is obtained (step S106). Next, the air-fuel ratio is obtained by a predetermined arithmetic expression, and the throttle valve 16 and / or the fuel injection valve 17 are controlled so as to obtain the obtained air-fuel ratio (step S107).

  Next, an ignition timing retardation amount corresponding to the gap wear amount is obtained (step S108). Next, the ignition timing is obtained by a predetermined arithmetic expression, the ignition coil 21 is controlled so as to ignite at the obtained ignition timing (step S109), and the process is temporarily terminated.

  If only air-fuel ratio control is performed, step S105 may be used instead of steps S108 and S109. When only the ignition timing control is performed, “basic air-fuel ratio × lean set value” may be used instead of steps S106 and S107.

Thus, in the present embodiment, the gap wear amount of the spark plug 11 is calculated based on the number of ignitions of the spark plug 11, and the air-fuel ratio and / or the ignition timing are determined according to the calculated gap wear amount. Be controlled. Therefore, according to 1st Embodiment of this invention, when the electrode gap of a spark plug expands, the change of the combustion state of an internal combustion engine can be suppressed.
<Second Embodiment>
A second embodiment of the control device for an internal combustion engine of the present invention will be described with reference to FIGS. The second embodiment is the same as the configuration of the first embodiment except that the combustion control process in the ECU 30 is different. Therefore, the description which overlaps with 1st Embodiment is abbreviate | omitted about 2nd Embodiment.

  In the present embodiment, the internal pressure sensor 23 detects the pressure in the cylinder 12 at the time of ignition (hereinafter also referred to as the in-cylinder internal pressure), and the voltage sensor 22 detects the voltage applied between the center electrode and the ground electrode of the spark plug 11. The electrode gap of the spark plug 11 is calculated based on the detected pressure and the detected voltage.

  A method for calculating the electrode gap of the spark plug 11 in the ECU 30 will be described with reference to FIGS. FIG. 6 is an example of a characteristic diagram showing a change in voltage applied to the center electrode of the spark plug 11. Here, since the potential of the ground electrode of the spark plug 11 is zero, the voltage applied to the center electrode represents the voltage applied between the center electrode and the ground electrode of the spark plug 11. Further, the “maximum voltage” in FIG. 6 represents the discharge start voltage, and corresponds to the discharge voltage actually generated between both electrodes of the spark plug 11.

  FIG. 7 is an example of a map that defines the relationship between the in-cylinder pressure during ignition and the maximum voltage applied to the center electrode of the spark plug 11 according to the electrode gap of the spark plug 11. Such a map may be constructed by measuring the maximum voltage when the in-cylinder pressure at the time of ignition is changed using, for example, an ignition plug having various electrode gaps.

  The CPU 301 of the ECU 30 reads the spark plug 11 from the map shown in FIG. 7 stored in the memory 302 based on the ignition cylinder pressure detected by the internal pressure sensor 23 and the maximum voltage detected by the voltage sensor 22. The electrode gap is specified.

  Next, in the present embodiment, the combustion control process executed by the ECU 30 will be described using the flowchart of FIG. This embodiment is the same as the first embodiment except that the processes of steps S101 and S102 of the combustion control process of FIG. 5 in the first embodiment are modified as shown in FIG. Therefore, the description which overlaps with 1st Embodiment is abbreviate | omitted about 2nd Embodiment. This combustion control process is executed mainly every few seconds to every few seconds, for example, regularly or irregularly while the vehicle is traveling.

  In FIG. 8, the ECU 30 first obtains the in-cylinder pressure during ignition (step S201) detected by the internal pressure sensor 23 and the maximum voltage detected by the voltage sensor 22 (step S202). Next, an electrode gap is specified based on the detected ignition cylinder pressure and the detected maximum voltage (step S203). Next, a gap wear amount is calculated based on the specified electrode gap (step S204).

  The method for calculating the gap wear amount from the identified electrode gap may be obtained from the difference between the obtained electrode gap and the initial electrode gap, for example. Here, the “initial electrode gap” is an electrode gap when the electrode is not worn, and is 1.1 mm, for example. In this case, the gap wear amount is obtained as “height”. When the gap wear amount is obtained as “volume”, the gap wear amount may be obtained by a predetermined calculation formula considering the shape of the electrode or the like, a map that defines the relationship between the electrode gap and the gap wear amount represented by the volume, or the like.

  When the horizontal axis of the map as shown in FIGS. 3 and 4 used in steps S106 and S108 in the flowchart of FIG. 5 is an electrode gap, step S204 in the flowchart of FIG. 8 may be omitted.

  As described above, in the present embodiment, the gap wear amount of the spark plug 11 is obtained based on the in-cylinder pressure and the ignition start voltage, and the combustion state of the internal combustion engine 1 is defined according to the obtained gap wear amount. The air-fuel ratio and / or the ignition timing as parameters to be controlled are controlled. Therefore, according to 2nd Embodiment of this invention, when the electrode gap of a spark plug expands, the change of the combustion state of an internal combustion engine can be suppressed.

  In addition, since the electrode gap of the spark plug can be specified directly from the ignition cylinder internal pressure and the discharge start voltage, compared to the case where the electrode gap is specified indirectly from the number of ignitions as in the first embodiment, Accuracy can be increased. Further, when the spark plug is replaced, there is no need to perform a special operation such as resetting the number of ignitions, which is very advantageous in practice.

  It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. Engine control devices and methods are also within the scope of the present invention.

It is a block diagram showing an internal combustion engine provided with the control apparatus of the internal combustion engine which concerns on 1st Embodiment, and its peripheral device. It is an example of the map which defines the relationship between the frequency | count of ignition and the amount of gap wear. It is an example of the map which defines the relationship between gap wear amount and lean increase amount. It is an example of the map which defines the relationship between gap wear amount and ignition timing retard amount. It is a flowchart of the combustion control process which ECU performs in 1st Embodiment. It is an example of the characteristic view which shows the change of the voltage concerning the center electrode of a spark plug. It is an example of the map which defines the relationship between the cylinder pressure at the time of ignition and the maximum voltage of discharge according to the electrode gap of a spark plug. It is a flowchart of the combustion control process which ECU performs in 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 11 ... Spark plug, 12 ... Cylinder, 13 ... Intake pipe, 14 ... Exhaust pipe, 15 ... Air flow meter, 16 ... Throttle valve, 17 ... Fuel injection valve, 18 ... Piston, 21 ... Ignition coil, 22 ... Voltage sensor, 23 ... Internal pressure sensor, 24 ... Top dead center pulse sensor, 30 ... ECU

Claims (7)

A control device for controlling an internal combustion engine provided in a cylinder with a spark plug having a center electrode and a ground electrode that are spaced apart and opposed to each other,
Distance specifying means for specifying a distance between the center electrode and the ground electrode;
A control device for an internal combustion engine, comprising: parameter changing means for changing a predetermined parameter for defining a combustion state of the internal combustion engine according to the specified distance.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the parameter changing means changes the air-fuel ratio of the internal combustion engine as the parameter.   The control apparatus for an internal combustion engine according to claim 1, wherein the parameter changing unit controls an ignition timing of the spark plug as the parameter. The distance specifying means includes
Ignition number detection means for detecting the number of ignitions of the spark plug;
The control device for an internal combustion engine according to any one of claims 1 to 3, further comprising: a calculation unit that calculates the distance based on the detected number of ignition times. The distance specifying means includes
An internal pressure detecting means for detecting the pressure in the cylinder;
Voltage detecting means for detecting a voltage applied between the center electrode and the ground electrode;
The control of the internal combustion engine according to any one of claims 1 to 3, further comprising: an arithmetic unit that calculates a distance of the spark plug based on the detected voltage and the detected pressure. apparatus.   The said parameter change means changes the said predetermined parameter so that the change of the said combustion state resulting from the change of the specified distance may become small, The Claim 1 thru | or 5 characterized by the above-mentioned. The internal combustion engine control device described. A control method for controlling an internal combustion engine provided with a spark plug having a spark plug having a center electrode and a ground electrode facing each other at a distance,
A distance specifying step of specifying a distance between the center electrode and the ground electrode;
And a parameter changing step of changing a predetermined parameter that defines the combustion state of the internal combustion engine according to the specified distance.

Images