JP6292135B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that controls the opening of a throttle valve and the amount of fuel.

  2. Description of the Related Art Conventionally, there is known a control device that changes the throttle valve opening of an internal combustion engine in accordance with, for example, a required value determined based on an accelerator pedal operation amount and a required value output from another electric control device. . Further, there is also known a control device that increases the output of the engine by increasing the amount of fuel supplied to the internal combustion engine when the throttle valve opening is larger than a predetermined threshold opening (for example, see Patent Document 1). reference.). Hereinafter, the internal combustion engine is simply referred to as “engine”, and the fuel increase performed when the throttle valve opening is larger than a predetermined threshold opening may be simply referred to as “output increase”.

JP 2014-152722 A

  However, when the engine temperature is low (that is, when the warm-up state of the engine has not reached the complete warm-up state), when the above-described output increase is performed, liquid fuel is generated in the spark plug (spark generating part of the spark plug). It is easy to occur that a large amount of is attached and does not evaporate sufficiently. As a result, there is a problem that so-called “spark plug smoldering” occurs.

  Especially when no-load racing operation (operation that frequently increases or decreases the amount of accelerator pedal operation when the transmission is in the neutral range) is performed when the engine temperature is low, when the transmission is in the driving range The amount of intake air (and hence the amount of fuel used for combustion) is smaller than when acceleration / deceleration operations are performed. For this reason, the combustion temperature (and hence the temperature of the spark plug) when the output increase is performed does not become sufficiently high, so that the smoldering of the spark plug is more likely to occur. However, the possibility of smoldering of the spark plug is increased when the output is increased frequently when the engine temperature is low even at the time of load.

  The present invention has been made in order to address the above-described problems, and one of its purposes is a control device for an internal combustion engine (hereinafter referred to as “the present invention”) that can reduce the possibility of smoldering of a spark plug. It is called "invention device").

The device of the present invention
A target value (that is, a target throttle valve opening) of an opening of a throttle valve (hereinafter sometimes referred to as “throttle valve opening”) disposed in an intake passage of the internal combustion engine is based on a required value. A throttle valve control unit for determining and changing the opening of the throttle valve so that the opening of the throttle valve matches the target value;
A fuel increasing portion that increases the amount of fuel supplied to the engine when the opening of the throttle valve is larger than a predetermined threshold opening (that is, performs output increasing);
Is provided.

  Accordingly, the device of the present invention changes the throttle valve opening so as to coincide with the target value, and increases the amount of fuel supplied to the engine when the throttle valve opening is larger than the threshold opening. The engine output is increased by reducing (enriching) the air-fuel ratio of the engine.

Furthermore, the throttle valve control unit
Wherein when the shift position of the transmission of a vehicle in which the engine is mounted is in a neutral range and before Symbol temperature of the engine is lower than the "threshold temperature set at a temperature below during warming up of the engine" When the target value exceeds “the upper limit opening set below the threshold opening”, the throttle valve opening is set to the upper limit opening.

  The determination as to whether or not the engine temperature is lower than the threshold temperature may be made by determining whether or not the cooling water temperature of the engine is lower than the threshold water temperature. It may be determined by determining whether or not the temperature is lower than the temperature, or may be determined by determining whether or not the engine body temperature detected by the temperature sensor installed in the engine body is lower than the threshold body temperature.

  According to the throttle valve control unit configured as described above, the throttle valve opening does not become larger than the “threshold opening that is a threshold for determining whether or not to increase the output as described above” when the engine temperature is low (cold). Therefore, the output increase is not performed. As a result, it is difficult to repeatedly cause a situation where a large amount of liquid fuel adheres to the spark plug and the evaporation of the fuel becomes insufficient. Therefore, the device of the present invention can reduce the possibility of smoldering spark plugs.

  Other objects, other features, and attendant advantages of the present invention will be readily understood from the description of each embodiment of the present invention described with reference to the following drawings.

FIG. 1 is a schematic diagram of an internal combustion engine control apparatus according to an embodiment of the present invention and an internal combustion engine to which the apparatus is applied. FIG. 2 is a flowchart showing a routine executed by the CPU shown in FIG. FIG. 3 is a flowchart showing a routine executed by the CPU shown in FIG. FIG. 4 is a time chart showing the operation of the conventional control device and the control device according to the embodiment of the present invention.

  Hereinafter, a control device for an internal combustion engine according to an embodiment of the present invention (hereinafter, also simply referred to as “the present embodiment”) will be described with reference to the drawings.

(Constitution)
The present embodiment is applied to the internal combustion engine 10 shown in FIG. The engine 10 is a known “spark ignition type, multi-cylinder, gasoline fuel port injection type, internal combustion engine”. The engine 10 supplies a gasoline mixture to the cylinder block portion 20 including a cylinder block, a cylinder block lower case, an oil pan, etc., a cylinder head portion 30 fixed on the cylinder block portion 20, and the cylinder block portion 20. And an exhaust system 50 for discharging exhaust gas to the outside.

  The cylinder block portion 20 includes a combustion chamber 25 formed by a cylinder wall surface, a piston crown surface, a cylinder head lower surface, and the like.

  The cylinder head portion 30 includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake cam shaft that drives the intake valve 32, and a variable intake timing that changes the phase angle of the intake cam shaft. Device 33, actuator 33a of variable intake timing device 33, exhaust port 34 communicating with combustion chamber 25, exhaust valve 35 for opening and closing exhaust port 34, exhaust camshaft 36 for driving exhaust valve 35, spark plug 37, spark plug 37 An igniter 38 including an ignition coil for generating a high voltage to be applied to the fuel cell and an injector (fuel injection means) 39 are provided.

The spark plug 37 is disposed so as to expose the spark generation part 37a at the upper part and substantially the center part of the combustion chamber 25. When a high voltage is applied based on the ignition signal, the spark plug 37 generates a spark for ignition from the spark generator 37a.
The injector 39 injects fuel into the intake port 31 in response to the injection instruction signal.

  The intake system 40 includes an intake manifold 41 including an intake manifold that communicates with the intake port 31 and forms an intake passage together with the intake port 31, an air filter 42 provided at an end of the intake pipe 41, and an intake pipe 41. A throttle valve 43 and a throttle valve actuator 43a that can change the opening cross-sectional area of the passage are provided. The throttle valve actuator 43a includes a DC motor and constitutes a throttle valve driving means. The throttle valve actuator 43a rotates the throttle valve 43 in response to the drive signal, thereby changing the opening cross-sectional area of the intake passage.

  The exhaust system 50 includes an exhaust manifold 51 communicating with the exhaust port 34, an exhaust pipe 52 connected to the exhaust manifold 51, a three-way catalyst 53, and the like. The exhaust port 34, the exhaust manifold 51, and the exhaust pipe 52 constitute an exhaust passage.

This implementation apparatus contains the sensor described below.
A hot-wire air flow meter 61 for measuring the intake air amount Ga per unit time;
A throttle position sensor 62 for detecting the opening degree TA of the throttle valve;
A cam position sensor 63 that generates a pulse signal each time the intake camshaft rotates by a predetermined angle;
A crank position sensor 64 that generates a pulse signal each time the crankshaft rotates a predetermined angle;
A water temperature sensor 65 for detecting the cooling water temperature THW of the engine 10;
An air-fuel ratio sensor 66 for detecting the air-fuel ratio of the exhaust gas flowing through the exhaust passage upstream of the catalyst 53;
An accelerator opening sensor 68 that detects an operation amount of the accelerator pedal 81 (that is, an accelerator pedal operation amount PA); and a shift position sensor 69 that detects a position (shift position position) of a shift lever of the transmission. The transmission of the vehicle on which the engine 10 is mounted is a well-known stepped automatic transmission, but the type of transmission is not particularly limited.

  The implementation apparatus includes an electric control device 70. The electric control device 70 is a microcomputer including an interface including a CPU, a ROM, a RAM, a backup RAM, and an AD converter. The interface is connected to the sensors 61 to 69, supplies signals from the sensors 61 to 69 to the CPU, and in response to instructions from the CPU, the actuator 33a, the igniter 38, the injector 39, and the throttle valve actuator of the variable intake timing device 33 Various signals are sent to 43a and the like to operate them.

(Operation)
Next, the operation of this embodiment apparatus will be described.
<Fuel injection control>
The CPU (hereinafter simply referred to as “CPU”) of the electric control device 70 is configured so that the crank angle of any cylinder matches a predetermined crank angle (for example, 90 ° before the intake top dead center of any cylinder). In addition, the “fuel injection control routine shown by the flowchart in FIG. 2” is executed for the arbitrary cylinder (hereinafter referred to as “fuel injection cylinder”).

  Therefore, at the timing described above, the CPU starts processing from step 200 in FIG. 2, sequentially performs the processing from step 210 to step 250 described below, proceeds to step 295, and once ends this routine.

  Step 210: The CPU determines an output increase value (output increase coefficient) Kpower based on the throttle valve opening TA. More specifically, the CPU sets the output increase value Kpower to “1” when the throttle valve opening TA is smaller than the predetermined threshold opening TAth, and the throttle valve opening TA is smaller than the threshold opening TAth. When it is larger, the output increase value Kpower is set to “1 + α”. Here, the value α is a positive value, for example, 0.2. Note that the threshold opening degree TAth is set to a throttle valve opening degree at which the increase in the intake air amount Ga is extremely small even when the throttle valve opening degree TA is increased in a region larger than the threshold opening degree TAth.

  Step 220: The CPU determines a warm-up increase value (warm-up increase coefficient) Kthw based on the coolant temperature THW representing the engine temperature. More specifically, when the cooling water temperature THW is lower than the “water temperature when the engine 10 is completely warmed up (warm-up increase threshold water temperature) THWath”, the CPU increases the warm-up increase value Kthw as “the cooling water temperature THW increases. It is set to “a value that decreases toward 1”. That is, the warm-up increase value Kthw increases in a range larger than “1” as the cooling water temperature THW is lower in the range lower than the water temperature THWath. Further, the CPU sets the warm-up increase value Kthw to “1” when the coolant temperature THW is equal to or higher than the water temperature THWath at the time of complete warm-up. The warm-up increase value Kthw is a value “1 + α” when the cooling water temperature THW is “the water temperature THWbth lower than the water temperature THWath”. Furthermore, “threshold temperature for setting the throttle valve opening upper limit value (threshold water temperature for setting the throttle valve opening upper limit value) THWcth”, which will be described later, is equal to or lower than the water temperature THWath and higher than the water temperature THWbth.

  Step 230: The CPU adopts the larger value Max (Kpower, Kthw) of the output increase value Kpower and the warm-up increase value Kthw as the final increase value (final increase coefficient) Kz.

  Step 240: The CPU determines a value obtained by multiplying the basic injection amount (Mc / stoich) by the final increase value Kz as the final fuel injection amount Finj. The basic injection amount is a value obtained by dividing the value Mc by the value stoich. Here, the value Mc is the amount of air (in-cylinder intake air amount) that the fuel injection cylinder sucks in the current intake stroke. The in-cylinder intake air amount Mc is determined by the intake air amount Ga measured by the air flow meter 61, the engine rotational speed NE obtained based on the output of the crank position sensor 64, and the table MapMc stored in the ROM. Is required. Further, the value stoich is the stoichiometric air fuel ratio (14.6 in this example). Therefore, when the final increase value Kz is “1”, the fuel of the basic injection amount (Mc / stoich) is injected into the fuel injection cylinder. As a result, the air-fuel ratio of the air-fuel mixture supplied to the fuel injection cylinder is It corresponds to the theoretical air fuel ratio. In other words, when the final increase value Kz is larger than “1”, the air-fuel ratio of the air-fuel mixture supplied to the fuel injection cylinder becomes an air-fuel ratio (rich air-fuel ratio) smaller than the stoichiometric air-fuel ratio.

  Step 250: The CPU injects fuel of the fuel injection amount Finj from the injector 39 disposed in the intake port 31 corresponding to the fuel injection cylinder. Thus, fuel injection is performed. Step 210, step 230, and step 240 execute a fuel increase unit (output increase) that increases the amount of fuel supplied to the engine 10 when the throttle valve opening TA is larger than a predetermined threshold opening TAth. (Increased part).

<Throttle valve opening control>
The CPU executes a “throttle valve opening control routine” shown by a flowchart in FIG. 3 every time a predetermined time elapses. Therefore, when the predetermined timing comes, the CPU starts the process from step 300 in FIG. 3 and proceeds to step 310 based on the signal from the shift position sensor 69 as to whether or not the shift position of the transmission is in the neutral range. judge.

  Assuming that the shift position of the transmission is in the neutral range, the CPU makes a “Yes” determination at step 310 to proceed to step 320 to determine whether or not the cooling water temperature THW is lower than the threshold water temperature THWcth. . The threshold water temperature (threshold temperature) THWcth is set to a value equal to or lower than the water temperature THWath indicating the complete warm-up of the engine 10.

  Assuming that the cooling water temperature THW is lower than the threshold water temperature THWcth, the CPU makes a “Yes” determination at step 320 to proceed to step 330 to set the value of the restriction flag XL to “1”. When the value of the limit flag XL is “1”, as will be described later, the throttle valve opening is limited to the upper limit opening TALimit or less. Thereafter, the CPU proceeds to step 350.

  On the other hand, if the shift position of the transmission is not in the neutral range, the CPU makes a “No” determination at step 310 to proceed to step 340. Further, if the cooling water temperature THW is equal to or higher than the threshold water temperature THWcth, the CPU makes a “No” determination at step 320 to proceed to step 340. In step 340, the CPU sets the value of the restriction flag XL to “0”. Thereafter, the CPU proceeds to step 350.

  In step 350, the CPU determines a target throttle valve opening (target value of the throttle valve opening) TAtgt based on the accelerator pedal operation amount PA. The target throttle valve opening degree TAtgt is determined to be “0” when the accelerator pedal operation amount PA is “0”, and to be a value that increases as the accelerator pedal operation amount PA increases. The maximum value of the target throttle valve opening degree TAtgt is larger than an upper limit opening degree TALimit described later. Further, the CPU may change the target throttle valve opening degree TAtgt according to the speed of the vehicle on which the engine 10 is mounted. In addition, the target throttle valve opening degree TAtgt determined in step 350 is also referred to as “basic target throttle valve opening degree” for convenience.

  Next, the CPU proceeds to step 360 to determine whether or not the value of the restriction flag XL is “1”. If the value of the limit flag XL is “1”, the CPU makes a “Yes” determination at step 360 to proceed to step 370 to determine whether the target throttle valve opening degree TAtgt is equal to or greater than the upper limit opening degree TALimit. To do. The upper limit opening TALimit is set to a value smaller by a predetermined opening γ than the above-described threshold opening TAth (an opening at which the output increase value Kpower starts to be set to a value “1 + α” larger than “1”). (See step 210 in FIG. 2).

  When the target throttle valve opening degree TAtgt is equal to or larger than the upper limit opening degree TALimit, the CPU makes a “Yes” determination at step 370 to proceed to step 380 to set the target throttle valve opening degree TAtgt to the upper limit opening degree TALimit. The process proceeds to step 390. In other words, the final target throttle valve opening degree TAtgt is a value obtained by limiting the basic target throttle valve opening degree TAtgt determined in step 350 by the upper limit opening degree TALimit. On the other hand, if the target throttle valve opening degree TAtgt is less than the upper limit opening degree TALimit, the CPU makes a “No” determination at step 370 to proceed directly to step 390. Accordingly, the final target throttle valve opening degree TAtgt is the same value as the basic target throttle valve opening degree TAtgt determined in step 350.

  In step 390, the CPU sends a drive signal to the throttle valve actuator 43a so that the actual throttle valve opening degree TA coincides with the target throttle valve opening degree TAtgt. As a result, when the value of the limit flag XL is “1”, the actual throttle valve opening degree TA is made to coincide with the “target throttle valve opening degree TAtgt which is not more than the upper limit opening degree TALimit”. In other words, when the value of the restriction flag XL is “1” by the processing of Step 360 to Step 390 (when the temperature of the engine 10 is lower than the threshold temperature set to be equal to or lower than the temperature at the completion of warming up of the engine 10) ) When the target value (basic target throttle valve opening TAtgt determined in step 350) exceeds the “upper limit opening TALimit set below the threshold opening TAth”, the throttle opening TA is set to the upper limit opening TALimit. Is done.

  On the other hand, if the value of the restriction flag XL is not “1” (when it is “0”) at the time when the CPU performs the process of step 360, the CPU makes a “No” determination at step 360 and proceeds to step 390. Proceed directly. Therefore, the actual throttle valve opening degree TA is made to coincide with the basic target throttle valve opening degree TAtgt determined in step 350. As described above, the opening degree of the throttle valve 43 is controlled.

  Step 350 realizes a function of determining the target value TAtgt of the throttle valve opening degree TA based on the required value (accelerator pedal operation amount PA). Further, Step 390 realizes a function of changing the throttle valve opening so that the throttle valve opening TA coincides with the target value TAtgt. In addition, Step 320, Step 330, Step 360-Step 390 are performed when the engine temperature is lower than the threshold temperature set below the engine warm-up temperature (“Yes” in Step 320). Refer to the determination.) When the target value (TAtgt) of the throttle valve opening TA exceeds the “upper limit opening (TALimit) set to be equal to or less than the threshold opening (TAth)”, the throttle valve opening is set to the upper limit opening (TA The function set to TALimit) is realized.

  FIG. 4A is a time chart showing respective values at the time of engine low temperature and no-load racing operation in a conventional apparatus to which the present invention is not applied. FIG. 4B is a time chart showing each value at the time of engine low temperature and no-load racing operation in the present embodiment. Here, it is assumed that the warm-up increase value Kthw is smaller than the value “1 + α”.

  According to the conventional apparatus, when the accelerator pedal operation amount PA is suddenly increased at time t1, and the throttle valve opening TA exceeds the threshold opening TAth at time t2, the value of the output increase value Kpower is “1”. Is set to “1 + α” to increase the output. Thereafter, when the accelerator pedal operation amount PA is suddenly reduced immediately before time t3, and the throttle valve opening TA falls below the threshold opening TAth at time t3, the output increase value Kpower is changed from “1 + α” to “1”. The output increase is stopped by returning to “1”. Since the engine temperature is low, a large amount of liquid fuel adheres to the spark plug due to the increase in output at times t2 to t3, and further, the fuel does not evaporate sufficiently after time t3. Therefore, if the no-load racing operation is repeated as at times t1 to t4, times t5 to t6, and times t7 to t8, the smoldering of the spark plug occurs.

  On the other hand, according to the present embodiment, when the accelerator pedal operation amount PA is suddenly increased at time T1, and the throttle valve opening TA exceeds the upper limit opening TALimit immediately before time T2, the throttle valve opens. The degree TA is maintained at the upper limit opening degree TALimit. As a result, the output increase value Kpower is maintained at “1”, so the output increase is not performed. Thereafter, when the accelerator pedal operation amount PA is suddenly reduced immediately before time T3 and the throttle valve opening TA falls below the upper limit opening TALimit immediately after time T3, the throttle valve opening TA is thereafter reduced to accelerator. Decreases as the pedal operation amount PA decreases. As a result, since the output increase is not performed at times T2 to T3 (further, at times T5 to T6 and times T7 to T8 in the illustrated example), a large amount of liquid fuel does not adhere to the spark plug. Therefore, the possibility of occurrence of smoldering spark plugs is reduced. Note that the fuel increase itself by the warm-up increase value Kthw is an increase that compensates for the amount of fuel adhering to the intake pipe wall, the intake valve, and the like when the engine is cold, and therefore has little effect on the smoldering of the spark plug.

  According to the present embodiment, the throttle valve opening TA is controlled so as not to exceed the upper limit opening TALimit when the engine is cold, and the output increase value Kpower is maintained at “1”. When the pedal operation amount PA is greatly depressed, the torque generated by the engine 10 is slightly lower than that of the conventional device. However, the increase in the engine rotational speed NE in no-load racing is completed within several hundred milliseconds, and the generated torque of the engine 10 is sufficiently large to increase the engine rotational speed NE when there is no load. A decrease in the torque generated by the engine 10 by the implementation device is hardly felt by the driver.

  Furthermore, a method (alternative method) is also conceivable in which the throttle valve opening TA is increased without any restriction at the engine low temperature and the output increase value Kpower is maintained at “1”. However, in the alternative method, the intake air amount increases when the throttle valve opening degree TA is equal to or higher than the upper limit opening degree TALimit. As a result, although the output increase is not performed, the basic injection amount (Mc / stoich) is Further increase in the amount of warm-up at low engine temperature increases the possibility of spark plug smoldering. On the other hand, in the present embodiment, since such a situation does not occur, it is possible to reduce the possibility of smoldering of the spark plug.

The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, this exemplary device, by providing the determination in step 310, that the throttle valve opening TA are controlled so as not to exceed the upper limit opening degree TALimit When the shift position of the transmission is in a neutral range. Further, although was determined based on the target value TAtg the throttle valve opening to the "accelerator pedal operation amount PA of the required value" (see step 350.), The request value is, for example, other electrical control It may be a value generated from a device (for example, a power management ECU in a hybrid vehicle) and transmitted to the electric control device 70 by communication.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 25 ... Combustion chamber, 31 ... Intake port, 37 ... Spark plug, 37a ... Spark generating part, 39 ... Injector, 43 ... Throttle valve, 43a ... Throttle valve actuator, 62 ... Throttle position sensor, 65 ... Water temperature Sensor 69 ... Shift position sensor 70 ... Electric control device.

Claims (1)

The target value of the throttle valve opening disposed in the intake passage of the internal combustion engine is determined based on the required value, and the throttle valve opening is changed so that the throttle valve opening matches the target value. A throttle valve control unit,
A fuel increasing unit that increases the amount of fuel supplied to the engine when the opening of the throttle valve is larger than a predetermined threshold opening;
An internal combustion engine control apparatus comprising:
The throttle valve control unit
The target value when the shift position of the transmission of a vehicle in which the engine is mounted temperature is and before Symbol Institution neutral range is lower than the threshold temperature set in the temperature below during warming up of the engine Is configured to set the throttle valve opening to the upper limit opening when the upper limit opening set below the threshold opening is exceeded,
Control device.

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