JP4968045B2 - Ignition control device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition control device for an internal combustion engine.

  2. Description of the Related Art Conventionally, a technique related to an ignition device for an internal combustion engine that performs ignition of a spark plug a plurality of times during one combustion stroke is known (see Patent Document 1). According to this technology, the ignitability of the air-fuel mixture can be ensured by performing the discharge of the spark plug a plurality of times.

JP-A-7-103122

  Depending on the operating state of the internal combustion engine, smoldering of the spark plug may occur. Spark plug smoldering refers to a phenomenon in which carbon generated by incomplete combustion or the like adheres to the insulator of the spark plug. When smoldering progresses, spark discharge does not occur and there is a risk of misfire. By the way, the fuel supplied to an internal combustion engine may contain many light components with good volatility, and may contain many heavy components with poor volatility. The occurrence frequency and progress of the smoldering of the spark plug also vary depending on the difference in fuel properties.

  Accordingly, an object of the present invention is to provide an ignition control device for an internal combustion engine that can execute the number of discharges suitable for preventing the smoldering of the spark plug by controlling the number of discharges according to the fuel properties.

  According to the above object, the determination means for determining the property of the fuel supplied to the combustion chamber of the internal combustion engine, the spark plug for igniting the mixture of the fuel and the intake air, and the determination result of the determination means once. And an ignition control device for controlling the number of discharges of the spark plug during the combustion stroke of the internal combustion engine. By controlling the number of discharges according to the fuel properties, the number of discharges suitable for preventing smoldering of the spark plug can be executed.

  In the above-described configuration, it is possible to employ a configuration including intake flow control means for controlling the flow rate of intake air in the combustion chamber according to the determination result of the determination means. By changing the flow rate of the intake air, the interval of ignition by the spark plug can be changed. Thereby, the frequency | count of discharge can be changed.

  In the above configuration, a configuration is adopted in which a swirl flow control valve that generates a swirl flow in the combustion chamber is provided, and the intake flow control means changes the strength of the swirl flow by controlling the swirl flow control valve. it can. By changing the strength of the swirling flow, the flow rate of the intake air in the combustion chamber can be controlled.

  The said structure WHEREIN: The said intake flow control means can employ | adopt the structure which controls the flow velocity of the intake air in the said combustion chamber by changing an engine speed. This is because when the engine speed changes, the flow rate of intake air in the combustion chamber also changes.

  In the above configuration, it is possible to employ a configuration in which a transmission for changing the transmission ratio is provided, and the intake flow control means changes the engine speed by controlling the transmission ratio of the transmission. This is because if the gear ratio changes, the engine speed also changes.

  The said structure WHEREIN: The said ignition control means can employ | adopt the structure which performs discharge, when the fuel supply to the said combustion chamber is stopped. By performing the discharge when the fuel supply to the combustion chamber is stopped, the smolder generation factor can be removed before the fuel supply to the combustion chamber is resumed.

  The said structure WHEREIN: The said ignition plug is provided with two or more with respect to a single cylinder, and the said ignition control means can employ | adopt the structure which controls the frequency | count of discharge with respect to these spark plugs.

  In the above configuration, the ignition control means may employ a configuration in which the number of discharges is increased as the degree of fuel heaviness increases.

  ADVANTAGE OF THE INVENTION According to this invention, the ignition control apparatus of the internal combustion engine which can perform the frequency | count of discharge suitable for preventing the smoldering of a spark plug by controlling the frequency | count of discharge according to a fuel property can be provided.

  A plurality of embodiments according to the present invention will be described below with reference to the drawings.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a hybrid system 1 according to the first embodiment. In FIG. 1, a hybrid system 1 includes an ECU 100, an engine system 200, a motor MG1, a motor MG2, a power split mechanism 300, an inverter 400, and a battery 500, and controls the hybrid vehicle 120.

  The ECU 100 is an electronic control unit that controls the overall operation of the hybrid system 1. The ECU 100 includes a ROM (Read Only Memory) and a RAM (Random Access Memory) (not shown), and is configured to execute a smoldering countermeasure process, which will be described later, according to a control program stored in the ROM. Also, the RAM temporarily stores various data acquired in the course of executing the smoldering countermeasure process, which will be described in detail later. The ECU 100 corresponds to ignition control means for controlling the number of discharges of the spark plug 16 during one combustion stroke according to the determination result of the fuel property sensor 50, and the flow rate of the intake air in the combustion chamber 15 is determined. It corresponds to the intake flow control means to be controlled.

  Engine system 200 functions as a main power source of hybrid vehicle 120. The detailed configuration of the engine system 200 will be described later.

  The motor MG1 functions as a generator for charging the battery 500 or as an electric motor that assists the driving force of the engine system 200. The motor MG2 functions as an electric motor that assists the output of the engine system 200 or as a generator for charging the battery 500.

  The power split mechanism 300 is a planetary gear mechanism including a sun gear, a planetary carrier, a pinion gear, and a ring gear (not shown). Among these gears, the rotation shaft of the sun gear on the inner periphery is connected to the motor MG1, and the rotation shaft of the ring gear on the outer periphery is connected to the motor MG2. The rotating shaft of the planetary carrier located between the sun gear and the ring gear is connected to the engine system 200, and the rotation of the engine system 200 is transmitted to the sun gear and the ring gear by the planetary carrier and further the pinion gear, and the engine system The power of 200 is configured to be divided into two systems. In the hybrid vehicle 120, the rotating shaft of the ring gear is connected to the transmission mechanism 121 in the hybrid vehicle 120, and the transmission mechanism 121 is connected to a CVT (continuously variable transmission) 123. The driving force is transmitted to the wheel 122 via the CVT 123.

  The CVT 123 is configured such that the gear ratio can be continuously changed by continuously changing the gear ratio under the control of the ECU 100.

  Inverter 400 converts DC power extracted from battery 500 into AC power and supplies it to motors MG1 and MG2, and also converts AC power generated by motors MG1 and MG2 into DC power and supplies it to battery 500. Is configured to be possible.

  The battery 500 is a rechargeable storage battery that functions as a power source for driving the motors MG1 and MG2. The battery 500 is provided with an SOC sensor 510 that detects the remaining capacity of the battery 500 and is electrically connected to the ECU 100.

  FIG. 2 is a schematic diagram of the engine system 200 according to the first embodiment. An engine system 200 shown in FIG. 1 has an engine 10 composed of a plurality of cylinders 12 (only one is shown in FIG. 1). In the engine 10, air flowing through the intake passage 13 is filled into the combustion chamber 15 via the intake port 13a, and a fuel / air mixture is generated by the fuel injection valve 14 that injects fuel into the intake port 13a. The When the air-fuel mixture is ignited by the spark plug 16, the air-fuel mixture burns, the piston 17 reciprocates, and the crankshaft 18 that is the output shaft of the engine 10 is driven to rotate. Exhaust gas generated by combustion in each combustion chamber 15 is discharged to the outside of the engine 10 through the exhaust passage 19 and the like via the exhaust port 19a.

  Output adjustment of the engine 10 is realized by driving a throttle valve 21 provided in the intake passage 13 by an actuator 22 or the like and adjusting the opening of the throttle valve 21. The throttle opening degree is adjusted by driving the actuator 22 in accordance with the depression amount of the accelerator pedal 23 operated by the driver.

  The engine 10 is provided with an intake valve 24 and an exhaust valve 25 for each cylinder 12 for opening and closing the intake passage 13 and the exhaust passage 19 at predetermined timings.

  An intake pressure sensor 74 for detecting the pressure of intake air (intake pressure) is provided downstream of the throttle valve 21 in the intake passage 13. Further, an accelerator sensor 75 for detecting the amount of depression of the accelerator pedal 23 by the driver, a throttle sensor 76 for detecting the throttle opening degree, and a water temperature sensor 77 for detecting the temperature of the cooling water for cooling the engine 10 are provided. .

  A swirl flow control valve 26 that generates a tumble flow that is a swirl flow in the combustion chamber 15 is disposed in the intake passage 13. The swirl flow control valve 26 is configured to be able to change the degree of opening in the intake passage 13 by the output from the ECU 100. The strength of the tumble flow generated in the combustion chamber 15 can be changed by changing the opening degree of the swirl flow control valve 26 according to the output from the ECU 100.

  The engine system 200 includes a fuel property sensor 50 that determines the property of the fuel supplied to the combustion chamber 15. The fuel property sensor 50 is provided in a fuel tank (not shown) that stores fuel to be supplied to the engine 10. The fuel property sensor 50 can detect the ratio of the high boiling point component contained in the fuel. Specifically, the degree of heavyness is detected by heating a part of the fuel stored in the fuel tank and detecting the change in the weight of the fuel per unit time before and after the heating. Also good. For example, in the case of a light fuel containing a large amount of low-boiling components, the rate of change in the weight of the fuel is large because the amount of vaporization per unit time due to heating is relatively large. In the case of a heavy fuel containing a large amount of high-boiling components, the rate of change in the weight of the fuel is small because the amount of vaporization per unit time is small even when heated. Thus, the degree of heavyness of the fuel supplied to the combustion chamber 15 can be determined by detecting the rate of change in the weight of the fuel due to heating. This information is output to the ECU 100. The fuel property sensor 50 corresponds to determination means for determining the property of the fuel. The fuel property may be determined by other known sensors and methods.

  Next, the smoldering countermeasure process executed by the ECU 100 will be described. FIG. 3 is a flowchart showing an example of smoldering countermeasure processing executed by the ECU 100. The smoldering countermeasure process is repeatedly executed at a predetermined cycle.

  First, the ECU 100 determines whether or not the property of the fuel supplied to the combustion chamber 15 corresponds to the heavy fuel by the fuel property sensor 50 (step S10). If the determination is affirmative, the ECU 100 determines whether or not the engine 10 is being driven (step S11). That is, it is determined whether fuel is injected from the fuel injection valve 14 and supplied into the combustion chamber 15. If the determination is affirmative, the ECU 100 sets the number of discharges of the spark plug 16 (step S12). Here, the number of discharges refers to the number of discharges during one combustion stroke. FIG. 4 is a map for setting the number of discharges of the spark plug 16. In the map of FIG. 4, the vertical axis represents the degree of heavy fuel, and the horizontal axis represents the number of discharges of the spark plug 16. As shown in FIG. 4, when the degree of heavyness of the fuel determined based on the output of the fuel property sensor 50 is large, the number of discharges is set to be large. This is because smoldering is more likely to occur as the degree of heavyness increases. Note that the map shown in FIG. 4 is calculated in advance through experiments or the like, and is stored in the ROM of the ECU 100.

  Next, the ECU 100 determines whether or not the current operation state is an operation region in which smoldering of the spark plug 16 is likely to occur based on outputs from various sensors (step S13). The operating region where smoldering is likely to occur depends on various engine conditions such as whether the fuel is injected into the intake port 13a as in this embodiment, or whether the fuel is directly injected into the combustion chamber 15. Since it fluctuates, it is desirable to make a determination using a map suitable for the engine in which this process is executed. This map is calculated in advance by experiments or the like and stored in the ROM.

  In the case of a negative determination, this series of smoldering countermeasure processing ends. When the anti-smoldering process is completed, the ECU 100 executes ignition with the number of discharges set in advance in the ECU 100 instead of the number of discharges set in step S12. This number of discharges is the same as the number of discharges set when the fuel supplied to the combustion chamber 15 is not heavy fuel (negative determination in step S10).

  If the determination in step S13 is affirmative, the ECU 100 controls the swirl flow control valve 26 to be closed (step S14). Thereby, the intake air passing through the intake passage 13 is throttled, and a strong tumble flow is generated in the combustion chamber 15. Thus, when the spark plug 16 is discharged, the discharge is temporarily blown off by the tumble flow, but is discharged again. Therefore, the discharge interval of the spark plug 16 is shortened, resulting in an increase in the number of discharges.

  Next, ECU 100 changes the gear ratio of CVT 123 to the high rotation side (step S15). Specifically, the ECU 100 controls the gear ratio so that the engine speed is higher than the current operating state on the equal output line P in the map shown in FIG. The equal output line P is a relationship line between the torque and the rotational speed when the output value of the engine 10 is constant. The map shown in FIG. 5 shows the load of the engine 10 on the vertical axis and the rotational speed of the engine 10 on the horizontal axis. Although only three equal output lines P are shown in FIG. 5, a plurality of them can be actually set. Normally, the CVT 123 operates in accordance with the operation line Q, but in the process of step S15, the ECU 100 controls to the side where the rotational speed of the engine 10 increases on the iso-output line P. This also increases the flow rate of the air-fuel mixture in the combustion chamber 15. As a result, the number of discharges of the spark plug 16 can be increased as a result.

  Next, the ECU 100 discharges the spark plug 16 with the number of discharges set in step S12 (step S16). By executing the discharge at the set number of discharges as described above, the smoldering of the spark plug 16 can be prevented and the ignition performance for the air-fuel mixture in the combustion chamber 15 can be improved.

  Next, when a negative determination is made in step S11, the ECU 100 determines whether or not the hybrid vehicle 120 is stopped (step S20). Specifically, the determination is made based on an output from a vehicle speed sensor (not shown). If the determination is affirmative, the ECU 100 determines whether the ignition is on (step S21). In the case of an affirmative determination, ECU 100 determines whether the state of charge of battery 500 is good or whether battery 500 is being charged based on the output from SOC sensor 510 (step S22). In the case of a negative determination, this series of smoldering countermeasure processing ends.

  If the determination is affirmative, the ECU 100 detects smoldering of the spark plug 16 (step S23). For example, the ECU 100 applies an ion current detection voltage to the spark plug 16 and detects combustion ions after ignition by the spark plug 16. At the same time, the smoldering state of the spark plug 16 is detected by detecting a change in the ionic current when the ignition coil (not shown) energization is started. Other known methods may be used.

  Next, the ECU 100 determines whether smoldering has occurred (step S24). In the case of negative determination, the smoldering countermeasure process is terminated. If the determination is affirmative, the ECU 100 sets the number of discharges (step S25). Note that the ECU 100 sets the number of discharges using a map different from the map used to set the number of discharges in step S12. That is, the number of discharges set in step S12 assumes that the engine 10 is in operation, and is the number of discharges required to ignite the air-fuel mixture, whereas it is set in step S25. This is because the number of discharges is based on the assumption that the engine 10 is stopped, the air-fuel mixture itself does not exist, and the purpose is to burn off carbon adhering to the insulator of the spark plug 16 by ignition. Note that the number of discharges set in step S25 is set such that the number of discharges increases as the degree of fuel severity increases, in the same manner as the number of discharges set in step S12. This is because if the fuel is heavy, incomplete combustion tends to occur while the engine 10 is being driven, and the amount of carbon adhering to the spark plug 16 tends to increase.

  Next, the ECU 100 performs discharge at the number of discharges set in step S25 (step S16). As described above, by igniting the spark plug 16 while the engine 10 is stopped, the cause of smoldering can be eliminated before the engine 10 is started, and the occurrence of smoldering at the time of starting can be prevented. Further, the ECU 100 prevents the voltage of the battery 500 from lowering by discharging the spark plug 16 when the state of charge of the battery 500 is good or the battery 500 is being charged.

  If the determination in step S21 is negative, the ECU 100 sets the number of discharges (step S30) and executes the discharge (step S16). The number of discharges in this case is also set so that the number of discharges increases as the degree of fuel heavy increases, as in steps S12 and S25. In this way, even when the ignition is off, by executing the discharge, the cause of the smoldering can be eliminated before the engine 10 is started, and the engine 10 is stopped before the warm-up of the engine 10 is completed. Smoldering can be prevented when the short trip operation is repeatedly executed. When the ignition is off, ignition is performed without detecting smoldering.

  As described above, the ECU 100 executes the smoldering countermeasure process. If the determination is positive in steps S10, S11, and S13, the ECU 100 sets the number of discharges according to the degree of heavy fuel (step S12) and controls the swirl flow control valve 26 to the closed side. However, although the gear ratio of the CVT 123 is changed to the high rotation side (step S15), for example, only the number of discharges may be set and the control of steps S14 and S15 may not be executed. Further, when the number of discharges is not set as in step S12 and the fuel is heavy fuel, the swirl flow control valve 26 is controlled to the closed side, or the gear ratio of the CVT 123 is changed to the high rotation side. May be. In addition, when steps S14 and S15 are not performed and the number of discharges is set according to the degree of heavy fuel, by setting the number of discharges suitable for the degree of heavyness, waste due to an increase in the number of discharges is wasted. Power consumption can be suppressed.

  Next, a hybrid system according to the second embodiment will be described. FIG. 6 is a schematic diagram of an engine system 200a employed in the hybrid system according to the second embodiment. In addition, about the same component as the engine system 200 employ | adopted as the hybrid system which concerns on Example 1, the description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 6, the engine 10 is provided with two spark plugs 16 and 16 a for a single cylinder 12. The spark plug 16a ensures the ignition of the air-fuel mixture by performing discharge together with the spark plug 16 in an operation region where smoldering is likely to occur. Specifically, when the fuel supplied to the combustion chamber 15 is not heavy fuel, the ECU 100 discharges only the spark plug 16 so that the fuel is heavy fuel, and the operating state of the engine 10 is In the region where smoldering is likely to occur, both the spark plugs 16 and 16a are discharged.

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

  In the first embodiment, the smoldering of the spark plug 16 is prevented by increasing the number of discharges of the spark plug 16, but control is performed so as to increase the electric power to the coil of the spark plug 16 according to the degree of heavyness of the fuel. May be. Even in this case, occurrence of smoldering can be prevented.

  In the first embodiment, the swirl flow control valve 26 that generates the tumble flow is employed. However, a swirl flow control valve may be employed.

  In the first embodiment, the ECU 100 changes the engine speed by changing the gear ratio of the CVT 123 to the high speed side. However, the present invention is not limited to the CVT, and employs a transmission of another system. It may be configured to change the engine speed by changing.

1 is a block diagram of a hybrid system 1 according to a first embodiment. 1 is a schematic diagram of an engine system according to Embodiment 1. FIG. It is the flowchart which showed an example of the smoldering countermeasure process which ECU performs. It is a map for setting the number of discharges of the spark plug. It is a map for controlling the gear ratio of CVT to the high rotation side. FIG. 6 is a schematic diagram of an engine system that is employed in a hybrid system according to a second embodiment.

Explanation of symbols

10 Engine (Internal combustion engine)
12 cylinder 13 intake passage 13a intake port 14 fuel injection valve 15 combustion chamber 16, 16a spark plug 26 swirl flow control valve 50 fuel property sensor (determination means)
120 Hybrid vehicle 123 CVT
100 ECU (ignition control means, intake air flow control means)
200, 200a Engine system 500 Battery 510 SOC sensor MG1, MG2 Motor

Claims (7)

Determination means for determining the properties of the fuel supplied to the combustion chamber of the internal combustion engine;
A spark plug for igniting a mixture of the fuel and the intake air;
Ignition control means for controlling the number of discharges of the spark plug during one combustion stroke according to the determination result of the determination means ;
Intake flow control means capable of controlling the flow rate of the intake air in the combustion chamber so that the discharge of the spark plug is temporarily blown off by the intake air according to the determination result of the determination means. An ignition control device for an internal combustion engine. A swirl flow control valve for generating a swirl flow in the combustion chamber;
The ignition control device for an internal combustion engine according to claim 1 , wherein the intake flow control means changes the strength of the swirl flow by controlling the swirl flow control valve. The ignition control device for an internal combustion engine according to claim 2 , wherein the intake flow control means controls the flow velocity of the intake air in the combustion chamber by changing the engine speed. It has a transmission that changes the gear ratio,
The ignition control device for an internal combustion engine according to claim 3 , wherein the intake flow control means changes the engine speed by controlling a gear ratio of the transmission. The ignition control device for an internal combustion engine according to any one of claims 1 to 4 , wherein the ignition control means performs discharge when fuel supply to the combustion chamber is stopped. A plurality of spark plugs are provided for a single cylinder,
The ignition control device for an internal combustion engine according to any one of claims 1 to 5 , wherein the ignition control means controls the number of discharges with respect to the plurality of spark plugs. The ignition control device for an internal combustion engine according to any one of claims 1 to 6 , wherein the ignition control means increases the number of discharges as the degree of fuel heaviness increases.

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