JP2015218706A - Internal combustion engine ignition control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine ignition control device capable of executing plug replacement at more appropriate replacement timing.SOLUTION: An ignition control device of an on-vehicle internal combustion engine 10 mounting therein an ignition plug 40 that includes counter electrodes 41 and 42, stores a load condition of the internal combustion engine 10 during driving of a vehicle, and calculates a required voltage necessary to generate spark discharge of the ignition plug 40 on the basis of a history of the stored load condition. The ignition control device determines the replacement timing of the ignition plug 40 on the basis of the calculated required voltage. That is, the ignition control device calculates a current electrode distance between the counter electrodes 41 and 42 in light of the history of the load condition, and calculates the required voltage on the basis of the calculated current electrode distance and an occasional operating state of the internal combustion engine 10.

Description

  The present invention relates to an ignition control device for an internal combustion engine mounted on a vehicle such as an automobile.

  The electrodes of the spark plug that cause spark discharge in the combustion chamber of the internal combustion engine are gradually consumed due to repeated spark discharge, and the distance between the electrodes gradually increases. If the distance between the electrodes is increased, the required voltage required to cause a spark discharge between the electrodes increases, and if the required voltage exceeds the withstand pressure of the spark plug, there may be a disadvantage associated with the damage of the spark plug. is there.

  Therefore, the required voltage is estimated so that the required voltage for the spark plug does not exceed the withstand voltage of the spark plug. For example, in Patent Document 1, the required voltage (estimated value) is calculated based on the engine rotation speed and the engine load.

JP 2009-174354 A

  By the way, it is considered that the consumption of the electrode of the spark plug is different for each vehicle. For this reason, it is desirable that the replacement time of the spark plug be set short in view of the safety side. However, considering that the operation pattern is different for each user, it can be said that the existing technology does not say that the spark plug is replaced at an appropriate replacement timing. In this case, for example, it is considered that there is a problem that the replacement of the spark plug is promoted despite the fact that the spark plug has not yet reached the end of its life, that is, the electrode has not worn much.

  In view of the above problems, it is a primary object of the present invention to provide an ignition control device for an internal combustion engine that can perform plug replacement at a more appropriate replacement timing.

  The present invention is an ignition control device for an on-vehicle internal combustion engine equipped with a spark plug having a counter electrode, and includes a load condition storage means for storing a load condition of the internal combustion engine and a load condition storage means during vehicle operation. A required voltage calculation means for calculating a required voltage required for generating spark discharge of the spark plug based on the stored load condition history, and a replacement timing determination for determining a replacement timing of the spark plug based on the calculated required voltage And means.

  In the above invention, the required voltage is calculated based on the load condition history of the internal combustion engine, and the execution time of the plug replacement is determined using the required voltage. Therefore, the plug can be replaced at an appropriate replacement time in consideration of the difference in the history of load conditions of the internal combustion engine.

1 is a schematic view of an internal combustion engine. The structure of a spark plug. The block diagram of calculation of the consumption amount of an electrode. Explanatory drawing of the map for electrode consumption amount calculation. The flowchart of plug replacement time determination. The flowchart of an output restriction process.

  Hereinafter, an ignition control device for an internal combustion engine according to the present invention will be described with reference to the drawings. The internal combustion engine is a gasoline engine or the like, and is used as a power source for a vehicle such as an automobile.

  As shown in FIG. 1, each cylinder 11 is formed in an engine block that constitutes a main body. An intake port 13 and an exhaust port 14 are formed in the cylinder head above the engine block so as to communicate with a combustion chamber 11 a formed in the cylinder 11. The cylinder head is mounted with an intake valve 15 and an exhaust valve 16 that are opened and closed as the camshaft rotates.

  An injector 18 and a spark plug 40 are attached to the engine block so as to protrude into the combustion chamber 11a. When the fuel injected from the injector 18 burns by the spark discharge of the spark plug 40, a crankshaft (not shown) rotates and the engine speed NE increases.

  Here, the structure of the spark plug 40 will be described with reference to FIG. 2. The spark plug 40 includes a center electrode 41 and a ground electrode 42 as counter electrodes. These electrodes 41 and 42 are opposed to each other with a discharge gap G having a predetermined inter-electrode distance. In the spark plug 40, a voltage higher than a required voltage, which is a minimum voltage necessary for generating a spark discharge, is applied between the center electrode 41 and the ground electrode 42, so that a spark is generated between the electrodes 41 and 42. Discharge occurs.

  In FIG. 1, the internal combustion engine 10 is provided with various sensors necessary for controlling the vehicle and the internal combustion engine 10. For example, a rotation speed sensor 33 that outputs a signal synchronized with the rotation of the crankshaft, a water temperature sensor 34 that detects a cooling water temperature of the internal combustion engine 10, an intake pressure sensor 36 that detects an intake pressure that is a pressure in the intake pipe, and an intake air amount An air flow sensor 37 that detects the exhaust air-fuel ratio, an air-fuel ratio sensor 38 that detects the exhaust air-fuel ratio, an accelerator opening sensor 39 that detects the accelerator opening from the amount of depression of an accelerator pedal (not shown), and the like. These sensors are connected to the input side of the ECU 30. Various actuators including the injector 18 and the spark plug 40 are connected to the output side of the ECU 30.

  The ECU 30 includes an A / D converter, a CPU, a RAM, a ROM, a flash memory (nonvolatile memory), and the like. The ECU 30 drives each actuator by causing the CPU to execute various programs stored in the ROM on the basis of the respective operating conditions (load conditions) of the internal combustion engine 10 detected by the sensors. Operation control of the engine 10 is performed.

  Specifically, the engine rotational speed NE and the crank angle are detected based on the output of the rotational speed sensor 33. Further, the engine load is calculated based on the engine rotational speed NE and the intake air amount detected by the air flow sensor 37. Further, the fuel injection timing and the ignition timing are determined based on the detected value of the crank angle. Then, the fuel injection amount is calculated based on the intake air amount and the engine load, and the injector 18 is driven and the spark plug 40 is driven so that a voltage is applied to the discharge gap G between the center electrode 41 and the ground electrode 42. Apply.

  By the way, the electrodes of the spark plug are gradually consumed due to repeated spark discharge, and the distance between the electrodes gradually increases. When the distance between the electrodes becomes longer, it becomes difficult for spark discharge to occur between the electrodes, and the required voltage required to generate spark discharge increases. If the required voltage increases and exceeds the pressure resistance of the spark plug, there may be inconveniences such as damage to the spark plug and the inability of proper spark discharge in the combustion chamber to prevent fuel from burning properly. .

  The consumption of the spark plug electrode changes according to the load condition history of the internal combustion engine. That is, as the frequency of operation under a high load condition increases, the electrode is more easily consumed, and if the required voltage exceeds the withstand voltage, there may be a disadvantage associated with damage to the spark plug. Therefore, when the plug replacement time is determined in advance, the required voltage exceeds the withstand voltage by setting the replacement time of the spark plug with reference to the case where the operation frequency is high under high load conditions. The occurrence of defects can be avoided. However, on the other hand, when the frequency of operation under low load conditions is high, plug replacement is performed in a state where the spark plug has not yet reached the end of its life, resulting in inconvenience that the use period of the spark plug is shortened. End up.

  In recent years, a supercharger has been adopted to increase the amount of air sucked into the combustion chamber, or a high compression ratio has been considered, and the combustion chamber is not properly operated at the ignition timing that causes spark discharge in the spark plug. The internal pressure tends to increase. In this case, since the difference in internal pressure increases between the high load condition and the low load condition, the difference in the degree of wear of the spark plug electrode due to the difference in the load condition tends to increase.

  Therefore, the ECU 30 of the present embodiment calculates (estimates) a required voltage necessary for generating spark discharge of the spark plug 40 based on the load condition history of the internal combustion engine 10. When the required voltage is equal to or higher than the withstand pressure of the spark plug 40, the fact that it is time to replace the spark plug 40 is notified. As described above, by determining the plug replacement time based on the history of the load conditions of the internal combustion engine 10, it is possible to perform plug replacement at a more appropriate replacement time.

  Specifically, the consumption amount of the spark plug 40, that is, the distance between the electrodes of the ignition plug 40 is calculated by reflecting the load condition history of the internal combustion engine 10, and the consumption amount is used for determining the plug replacement timing. That is, as the frequency of the high load condition increases, the consumption amount of the spark plug 40 increases and the distance between the electrodes increases, so that a required voltage that is a determination parameter for plug replacement timing is calculated.

  That is, as shown in the block diagram of FIG. 3, the inter-electrode distance calculation processing unit 50 is stored in the ROM of the ECU 30. The arithmetic processing unit 50 uses the engine speed NE and the engine load as indices to calculate a weighting value for the change in the discharge gap G per combustion, and the number of combustions for calculating the number of combustions per unit time. The calculation unit 52, the multiplication unit 53 that multiplies the outputs of the calculation map 51 and the combustion frequency calculation unit 52, and the amount of change in the interelectrode distance per unit time that is the calculation result of the multiplication unit 53 is integrated. An integration unit 54 that calculates the amount, and an interelectrode distance calculation unit 55 that calculates the current interelectrode distance using the electrode consumption amount calculated by the integration unit 54 are provided.

  In the calculation map 51, for each of a plurality of combinations of the engine rotational speed NE and the engine load, each weight value is determined by measuring the amount of change in the interelectrode distance with an actual machine or the like. In the calculation map 51 of FIG. 4, the weighting value is determined based on the fact that the amount of change in the interelectrode distance increases as the engine rotational speed NE and the engine load each increase. Also, in the region A in the figure, which is a high load region, the weighting value is a large value in consideration that the amount of change in the interelectrode distance increases as the ignition timing approaches the compression top dead center (near TDC). ing. In this case, by providing a plurality of regions having similar weight values, the weight value is selected according to which region the combination of the detected value of the engine speed NE and the engine load belongs to. It has become.

  The number-of-combustions calculation unit 52 calculates the number of combustions per unit time according to the number of cylinders of the internal combustion engine 10 (four cylinders in the present embodiment). A predetermined number of times is determined according to the load condition of the internal combustion engine 10. A parameter is selected. Specifically, the engine speed NE (rpm) is converted into a unit time (here, 1 second), and the number of combustion is calculated by multiplying the number of combustion for each rotation. When fuel cut or engine stall occurs, the number of combustions per unit time is set in consideration of the state.

The ECU 30 obtains a current inter-electrode distance (estimated value) based on the engine rotational speed NE detected by the rotational speed sensor 33 and the engine load, using the inter-electrode distance calculation processing unit 50. Then, the ECU 30 calculates a required voltage (estimated value) based on the current interelectrode distance calculated by the arithmetic processing unit 50 and the operating condition of the internal combustion engine 10 at that time. For example, the required voltage is calculated using an arithmetic expression shown in Expression (1).
Required voltage = Base value + K1 x NE (rpm)
+ K2 x Pm (kPa)
-K3 x SA (BTDC)
+ K4 × λ
+ K5 x Trq (Nm)
+ K6 × L (mm) (1)
In Equation (1), NE is the engine speed, Pm is the intake pressure, SA is the ignition timing, λ is the excess air ratio, Trg is the torque, and L is the current interelectrode distance. K1 to K6 are coefficients (parameters) set individually for each internal combustion engine. Here, the required voltage is calculated as a larger value as the engine speed NE, the intake pressure Pm, the torque Trq, and the interelectrode distance L are increased. Moreover, it is calculated as a larger value as the excess air ratio λ becomes leaner. Furthermore, the required voltage is calculated as a smaller value as the ignition timing SA is advanced with respect to TDC.

  Next, a process for determining the replacement timing of the spark plug 40 will be described with reference to FIG. The following processing is repeatedly performed every combustion cycle (for example, 20 ms cycle) in a state where an ignition switch of a vehicle (not shown) is turned on and the internal combustion engine 10 is operable. Note that the initial value of the distance between the electrodes of the spark plug 40 is input to the flash memory of the ECU 30 when the spark plug 40 starts to be used (at the time of replacement). In the initial state, a plug replacement flag, which will be described later, is off.

  In FIG. 5, it is determined in step S10 whether or not the plug replacement flag is off. The plug replacement flag is switched on when it is determined that the estimated value of the required voltage is equal to or higher than the withstand voltage of the spark plug 40 in the process described later. If the plug replacement flag is off and the determination is affirmative, the engine rotational speed NE is acquired from the detection signal of the rotational speed sensor 33 in step S11. In step S12, the engine load is acquired. For example, the accelerator opening is acquired from the detection signal of the accelerator opening sensor 39 as the engine load.

  In step S13, the current interelectrode distance is calculated. Specifically, the amount of change in the inter-electrode distance per unit time is calculated by associating each parameter acquired in steps S11 and S12 with the calculation map 51 (see FIG. 4) of the calculation processing unit 50. Then, the amount of change in the interelectrode distance per unit time is integrated to obtain the amount of change in the interelectrode distance from the start of use. Then, the current inter-electrode distance is calculated by adding the change amount of the inter-electrode distance to the initial value of the inter-electrode distance of the spark plug 40.

  In step S14, a required voltage is calculated. In the present embodiment, the required voltage is calculated by substituting the current inter-electrode distance calculated in step S13 and the operating condition of the internal combustion engine 10 detected by various sensors into the arithmetic expression of Expression (1). Is calculated.

  In step S15, it is determined whether the required voltage is equal to or higher than the withstand voltage of the spark plug 40. Note that the pressure resistance information of the spark plug 40 is recorded in advance in a flash memory or the like. If it is determined in step S15 that the required voltage is less than the withstand voltage, this process is terminated. On the other hand, if it is determined that the required voltage is higher than the withstand voltage, the replacement timing flag of the spark plug 40 is turned on in step S16.

  If a negative determination is made in step S10, that is, if the plug replacement time flag is on, the process proceeds to step S17, and a notification for prompting the plug replacement of the spark plug 40 is output. For example, a display that prompts the user to replace the plug is displayed on an instrument panel of a vehicle (not shown).

  If the plug replacement time flag is on, the output restriction process shown in FIG. 6 is performed. Specifically, in step S21, it is determined whether or not the plug replacement time flag is off. If it is off and an affirmative decision is made, normal processing is performed in step S22. In the normal process, normal engine control is performed based on the operating conditions of the internal combustion engine 10 detected by various sensors. If a negative determination is made in step S21, output restriction is performed in step S23. For example, the output restriction of the internal combustion engine 10 is performed with respect to the depression amount of the accelerator pedal. Specifically, the required voltage is limited by limiting the target torque for accelerator operation, correcting the ignition timing to the retard side, limiting the engine rotational speed NE, or performing shift limitation. Do (lower). Further, the required voltage may be limited by enriching the air-fuel ratio of the air-fuel mixture.

  As described above, when the plug replacement timing flag is on, the output restriction of the internal combustion engine is performed, so that an increase in the required voltage can be suppressed at the replacement timing of the spark plug 40. In this case, damage to the spark plug 40 can be suppressed before the plug replacement is performed.

  According to the present invention, the following excellent effects can be obtained.

  The consumption of the electrodes 41 and 42 of the spark plug 40 is considered to be different for each vehicle. Therefore, considering the safety side, it is desirable to set the replacement timing of the spark plug 40 short. However, considering that the operation pattern is different for each user, it can be said that the existing technology does not say that the spark plug 40 is replaced at an appropriate replacement timing. Therefore, the required voltage is calculated based on the load condition history of the internal combustion engine 10, and the execution time of plug replacement is determined using the required voltage. In this case, the plug replacement can be performed at an appropriate replacement time in consideration of the difference in the history of load conditions of the internal combustion engine.

  -When calculating the required voltage, the distance between the electrodes is calculated in consideration of the load condition history, and the required voltage is calculated by reflecting the engine operating state for each distance between the electrodes. As a result, the required voltage can be calculated with high accuracy, and as a result, the accuracy of the plug replacement determination based on the required voltage can be increased.

  The integrated value of the change amount of the interelectrode distance can be calculated based on the load condition of the internal combustion engine 10, and the current interelectrode distance can be calculated using the integrated value of the change amount of the interelectrode distance.

  The amount of change in the interelectrode distance can be calculated using characteristic data indicating the relationship between the engine rotational speed and the engine load and the amount of change in the interelectrode distance.

  When the required voltage is equal to or higher than the withstand voltage of the spark plug 40 and it is determined that the spark plug 40 is in the replacement timing, the output of the internal combustion engine 10 is limited, and the spark plug 40 until the plug replacement is performed. Damage can be suppressed.

  The present invention is not limited to the description of the above embodiment, and may be implemented as follows.

  The calculation map 51 (characteristic data) may be determined in consideration of the magnitude of airflow generated in the cylinder. That is, when the air flow in the cylinder 11 is strong, the spark discharge is blown out, and a phenomenon in which several spark discharges are intermittently generated, that is, re-discharge due to blow-out easily occurs. Since the re-discharge is repeated until the discharge energy of the spark plug 40 is consumed, the consumption of the electrodes 41 and 42 tends to increase as the number of re-discharges increases. Therefore, the amount of change in the distance between the electrodes in each combustion cycle may be calculated using the strength of the airflow in the cylinder and the number of redischarges as parameters. For example, the change amount of the interelectrode distance is calculated by substituting the change amount of the interelectrode distance calculated by the calculation map 51 of FIG. 4 into the calculation map 51 using the strength of the airflow and the number of re-discharges as parameters. In this case, the consumption amount of the electrode can be estimated with higher accuracy in consideration of the number of re-discharges in the spark plug 40.

  -It is good also as a structure which notifies that the electrode consumption is earlier than the predetermined standard state according to the amount of electrode consumption (distance between electrodes). For example, the standard amount of electrode consumption is determined in accordance with the travel distance of the vehicle, the cumulative number of combustions of the internal combustion engine 10, and the like. If it is determined that the electrode consumption is appropriate with respect to the travel distance or the like, the ECU 30 notifies the user, and if it is determined that the electrode consumption is early with respect to the travel distance or the like, the ECU 30 also indicates that. To the user. In this case, when the user unintentionally performs an overload operation, the user can correct it.

  A plurality of determination values may be defined as determination values for determining the magnitude of the required voltage. Specifically, when the required voltage reaches the first determination value (<withstand voltage), the ECU 30 notifies that the requested voltage will soon reach the withstand voltage, that is, it is time to replace the plug. When the voltage reaches the second determination value (= withstand voltage), it is notified that the plug replacement time has come, and the torque of the internal combustion engine is limited.

  In FIG. 5, when the current inter-electrode distance calculated in step S13 is less than a predetermined value, that is, when the electrode is not consumed, it is determined in step S15 whether the required voltage is equal to or higher than the withstand voltage. Processing may be omitted.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 40 ... Spark plug, 41 ... Center electrode, 42 ... Ground electrode.

Claims (6)

An on-vehicle internal combustion engine ignition control device equipped with a spark plug (40) having counter electrodes (41, 42),
Load condition storage means for storing a load condition of the internal combustion engine during vehicle operation;
Request voltage calculating means for calculating a required voltage required for occurrence of spark discharge of the spark plug based on the history of the load condition stored by the load condition storage means;
Replacement timing determination means for determining the replacement timing of the spark plug based on the calculated required voltage;
An ignition control device for an internal combustion engine, comprising: Inter-electrode distance calculation means (50) for calculating the current inter-electrode distance of the counter electrode in consideration of the history of the load condition,
2. The internal combustion engine according to claim 1, wherein the required voltage calculating unit calculates the required voltage based on the current inter-electrode distance calculated by the inter-electrode distance calculating unit and the operating state of the internal combustion engine at that time. Engine ignition control device.   The interelectrode distance calculation means is a change amount calculation means (51-53) for calculating the change amount of the interelectrode distance per unit time based on the load condition, and a means for integrating the change amount of the interelectrode distance. The ignition control device for an internal combustion engine according to claim 2, further comprising: (54) and means (55) for calculating the current inter-electrode distance using an integrated value of the inter-electrode distance.   The change amount calculation means calculates the change amount of the interelectrode distance by using characteristic data indicating the relationship between the engine rotation speed and the engine load as the load condition and the change amount of the interelectrode distance. An ignition control device for an internal combustion engine according to claim 1.   The ignition control device for an internal combustion engine according to claim 4, wherein the characteristic data is a map that determines a change amount of the inter-electrode distance per unit time based on the engine rotational speed and the engine load.   The ignition control device for an internal combustion engine according to any one of claims 1 to 5, further comprising output limiting means for limiting an output of the internal combustion engine when the calculated required voltage is equal to or higher than a withstand voltage of the ignition plug.

Images