JP2019148181A - Controller of internal combustion engine - Google Patents

Abstract

To obtain acceleration response matched with driver's intention of a vehicle.SOLUTION: A controller of an internal combustion engine is configured to: when an amount of increase in accelerator opening per unit time exceeds a threshold, execute fuel injection amount increase correction for enriching an air-fuel ratio of air-fuel mixture charged in a cylinder as compared with the case where it is not; and set the threshold at the time when the accelerator opening is large lower than the threshold at the time when the accelerator opening is smaller.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device that controls an internal combustion engine mounted on a vehicle.

  When the accelerator opening, more specifically, the accelerator pedal depression amount or the throttle valve opening exceeds a predetermined threshold, the fuel injection amount is increased to enrich the air-fuel ratio of the air-fuel mixture filled in the cylinder. It is known to perform so-called power increase correction (see, for example, the following patent document). This power increase correction is intended to increase the engine torque output from the internal combustion engine, thereby promoting the acceleration of the engine speed and the vehicle speed.

  On the other hand, if the amount of air-fuel mixture charged in the cylinder rapidly increases at a low engine speed, knocking may be induced. Conventionally, even if the driver depresses the accelerator pedal rapidly, the opening of the throttle valve is gradually increased, and the occurrence of knocking is suppressed by gradually retarding the ignition timing. However, both of these measures act to delay the acceleration of the engine speed and the vehicle speed. As a result, the acceleration response as desired by the driver was not necessarily realized.

JP 2012-163067 A

  An object of the present invention is to obtain an acceleration response that matches a vehicle driver's intention.

  In the present invention, when the increase amount of the accelerator opening per unit time exceeds the threshold value, the fuel injection amount increase correction is performed to enrich the air-fuel ratio of the air-fuel mixture filled in the cylinder as compared with the case where the accelerator opening amount exceeds the threshold value. Therefore, the control device for the internal combustion engine is configured to set the threshold value when the accelerator opening is large to be lower than the threshold value when the accelerator opening is smaller.

  That is, if the increase amount per unit time of the accelerator opening is larger than the threshold value, the fuel injection amount is increased even if the accelerator opening is not yet large. As a result, the engine speed and the vehicle speed can be accelerated earlier than before.

  In addition, by increasing the fuel injection amount, the temperature in the combustion chamber of the cylinder can be lowered using the latent heat (vaporization heat) of the fuel, and knocking is less likely to occur. If the risk of occurrence of knocking decreases, it is permitted to quickly increase the opening of the throttle valve and advance the ignition timing.

  If the accelerator opening is already large, the fuel injection amount is increased even if the increase in the accelerator opening per unit time is not large. This is because a large accelerator opening indicates that the driver has an intention to accelerate.

  If noise is mixed in or superimposed on the output signal of the sensor for detecting the accelerator opening, it is known by referring to the output signal even though the driver does not actually step on the accelerator pedal. It is possible that the amount of increase in accelerator opening per unit time exceeds the threshold value. Then, the engine speed and the vehicle speed may be accelerated without following the driver's intention. Accordingly, if the increase amount per unit time of the accelerator opening obtained by referring to the sensor output signal exceeds the upper limit value, the increase correction based on the increase amount exceeding the threshold value is not executed. It is preferable to do so.

  Further, when the driver tries to accelerate the vehicle at a stage where the vehicle speed is relatively low, it is assumed that the accelerator pedal is not necessarily depressed rapidly. In such a case, it is preferable to set the threshold value when the vehicle speed is low to be lower than the threshold value when the vehicle speed is higher so that the engine speed and the vehicle speed can be accelerated quickly.

  According to the present invention, it is possible to obtain an acceleration response that matches the vehicle driver's intention.

The figure which shows schematic structure of the internal combustion engine for vehicles and control apparatus in one Embodiment of this invention. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment performs according to a program. The figure which shows the relationship between the target air fuel ratio of the air-fuel | gaseous mixture which the control apparatus of the embodiment controls, an accelerator opening degree, and its variation | change_quantity per unit time. The figure which shows the relationship between the threshold value and the vehicle speed which the control apparatus of the embodiment sets.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (for example, three cylinders, one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream. The opening of the throttle valve 32, which is an intake throttle valve that increases or decreases the amount of intake air flowing into the cylinder 1, changes according to the amount of depression of the accelerator pedal by the driver of the vehicle. As a general rule, the greater the depression amount of the accelerator pedal, the greater the opening of the throttle valve 32.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  An external EGR (Exhaust Gas Recirculation) device 2 realizes a so-called high-pressure loop EGR. The EGR device 2 includes an external EGR passage 21 that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21. And an EGR valve 23 that controls the flow rate of the EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, specifically to a surge tank 33.

  An ECU (Electronic Control Unit) 0 serving as a control device for an internal combustion engine according to the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface of the ECU 0 is output from a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle sensor (engine rotation sensor) that detects the rotation angle of the crankshaft and the engine speed of the internal combustion engine. Crank angle signal b, accelerator pedal depression amount or throttle valve 32 opening as an accelerator opening (in other words, required engine load factor), an accelerator opening signal c output from a sensor, a brake pedal depression A brake pedal amount signal d output from a sensor for detecting the amount or a sensor for detecting a master cylinder pressure which is a pressure of hydraulic fluid discharged from the master cylinder, an intake air temperature in the intake passage 3 (particularly, the surge tank 33), and Intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake pressure, internal combustion engine Cooling water temperature signal f output from a water temperature sensor for detecting a cooling water temperature indicating temperature, cam angle signal g output from a cam angle sensor at a plurality of cam angles of the intake camshaft, and an atmospheric pressure sensor for detecting atmospheric pressure The atmospheric pressure signal h etc. output from is input.

  From the output interface of the ECU 0, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening operation for the EGR valve 23. The signal l and the like are output.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is sucked into the cylinder 1. Estimate the amount of intake (may be fresh air). Various operations such as required fuel injection amount corresponding to the intake air amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR gas amount), etc. Determine the parameters. The ECU 0 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

  The ECU 0 according to the present embodiment executes a power increase for increasing the fuel injection amount in response to the driver's intention to accelerate the vehicle. Usually, the fuel injection amount is adjusted so that the air-fuel ratio of the air-fuel mixture filled in the cylinder 1 becomes the stoichiometric air-fuel ratio or a target air-fuel ratio in the vicinity thereof. However, during the increase correction, the fuel injection amount is increased so that the air-fuel ratio of the air-fuel mixture becomes richer than usual, that is, richer than the theoretical air-fuel ratio. By this increase correction, the engine torque output from the internal combustion engine can be increased, and acceleration of the engine speed and vehicle speed can be promoted.

  Whether or not the power increase correction is necessary is determined based on the current accelerator opening, the increase per unit time (in other words, the increase speed of the accelerator opening), and the current vehicle speed. As shown in FIG. 2, the ECU 0 performs power increase correction that enriches the air-fuel ratio of the air-fuel mixture as compared with the case where the increase amount per unit time of the accelerator opening exceeds the threshold (step S <b> 2). (Step S4).

  The threshold value to be compared with the amount of increase in accelerator opening per unit time is set according to the current accelerator opening and vehicle speed (step S1). Basically, the threshold is set higher as the accelerator opening is smaller, and the threshold is set lower as the accelerator opening is larger. Even if the current accelerator opening is not yet large, if the driver of the vehicle strongly depresses the accelerator pedal and the increase amount per unit time of the accelerator opening exceeds the threshold value, the power increase correction is performed. As a result, the engine speed and the vehicle speed can be accelerated at an early stage. In addition, the combustion chamber temperature of the cylinder 1 can be lowered using the increased latent heat of the fuel. This is effective in suppressing knocking in a low-rotation and high-load operation region where the risk of occurrence of knocking is high, that is, in a situation where the engine speed is low but the accelerator opening is large. If knocking is less likely to occur, the opening of the throttle valve 32 is quickly increased to increase the intake air amount, and the ignition timing is further advanced to allow MBT (Minimum Advance for Best Torque). This also contributes to improving the acceleration performance of the vehicle.

  Conversely, if the accelerator opening is already large, it is considered that the driver has a clear intention to accelerate, so even if the increase in accelerator opening per unit time is not large, the power increase correction It is desirable to implement. Therefore, the threshold value is set low.

  By adjusting the threshold value according to the accelerator opening, as shown in FIG. 3, both the accelerator opening and the increase amount per unit time have an influence on the necessity of performing the power increase correction. In FIG. 3, the solid line indicates the target value of the air-fuel ratio when the increase amount per unit time of the accelerator opening is large, and the chain line indicates the target value of the air-fuel ratio when the increase amount per unit time of the accelerator opening is small. The broken line represents the target value of the air-fuel ratio in the case between them. The air-fuel ratio 14.65 is a target value of a normal air-fuel ratio, and the air-fuel ratio 12.5 is a target value of the air-fuel ratio during power increase correction. As shown in FIG. 3, when the increase amount per unit time of the accelerator opening is large, the engine load is lower, that is, from a region where the accelerator opening is small, compared to the case where the increase amount per unit time is small. Power increase correction starts.

  Furthermore, under the condition that the current accelerator opening is equal, as shown in FIG. 4, the threshold is set lower as the current vehicle speed is lower, and the threshold is set higher as the vehicle speed is higher. The reason for adjusting the threshold according to the vehicle speed is that the accelerator pedal is not necessarily depressed suddenly and strongly even if the driver intends to accelerate the vehicle when the vehicle speed is relatively low.

  The memory of the ECU 0 stores in advance map data that defines the relationship between the accelerator opening and the vehicle speed and a threshold value to be compared with the amount of increase in the accelerator opening per unit time. In step S1, the ECU 0 searches the map using the current accelerator opening and the vehicle speed as keys, and knows the threshold value to be set.

  However, even if the increase amount per unit time of the accelerator opening exceeds the threshold value, the power increase correction is not always performed. The ECU 0 refers to the accelerator opening signal c output from the sensor for detecting the accelerator opening, and repeatedly calculates the accelerator opening and the amount of increase per unit time in a short cycle. However, when noise is mixed in or superimposed on the signal c, the increase amount per unit time of the accelerator opening calculated by the ECU 0 becomes enormous even though the driver does not actually step on the accelerator pedal strongly. It can happen that the threshold is exceeded. Then, the power increase correction may be performed without accelerating the driver's intention to accelerate the vehicle.

  Therefore, when the increase amount per unit time of the accelerator opening exceeds the upper limit value (step S3), the ECU 0 assumes that it is an abnormal value due to noise, even if the increase amount exceeds the threshold value. No power increase correction is performed (step S5). Specifically, when the increase amount of the accelerator opening per unit time exceeds the upper limit value indicating abnormality, the ECU 0 regards the increase amount of the accelerator opening per unit time as 0 or a local minimum value close to 0. Thus, the condition of step S2 is prevented from being true.

  Therefore, the ECU 0 not only while the increase amount per unit time of the accelerator opening exceeds the upper limit value, but also after the increase amount per unit time is reduced to the upper limit value or less, for a predetermined time (for example, Until the elapse of several tens of milliseconds to several hundred milliseconds), the increase amount per unit time of the accelerator opening is continuously regarded as 0 or a local minimum value close to 0. In other words, once the increase amount per unit time of the accelerator opening exceeds the upper limit value, the power increase correction is performed until the predetermined time elapses after the increase amount per unit time decreases below the upper limit value. Not implemented.

  The ECU 0 of the present embodiment repeatedly executes the above-described steps S1 to S5 in a short cycle.

  In the present embodiment, when the increase amount per unit time of the accelerator opening exceeds a threshold value, the fuel injection amount increase correction for enriching the air-fuel ratio of the air-fuel mixture filled in the cylinder 1 as compared to the case where it is not so. The control device 0 for the internal combustion engine is configured such that the threshold value when the accelerator opening is large is set lower than the threshold value when the accelerator opening is smaller. According to the present embodiment, an acceleration response that matches the intention of the vehicle driver can be obtained.

  In addition, if the increase amount per unit time of the accelerator opening obtained by referring to the output signal c of the sensor for detecting the accelerator opening exceeds the upper limit value, the increase amount exceeds the threshold value. Therefore, even if noise is mixed in or superimposed on the output signal c of the sensor, it is not necessary to execute the increase correction by mistake, and the engine speed is not in line with the driver's intention. Further, acceleration of the vehicle speed can be avoided.

  Further, the threshold value when the vehicle speed of a vehicle equipped with an internal combustion engine as a power source for traveling is low is set to be lower than the threshold value when the vehicle speed is higher, and the vehicle speed is low. The engine speed and vehicle speed can be quickly accelerated in accordance with the driver's intention to accelerate the vehicle.

  The present invention is not limited to the embodiment described in detail above. For example, the air-fuel ratio of the air-fuel mixture filled in the cylinder 1 becomes rich during fuel injection amount increase correction, and the temperature in the combustion chamber of the cylinder 1 decreases due to the latent heat of the fuel, thereby reducing the risk of knocking. Therefore, it is allowed to reduce the degree of retarding the ignition timing in order to prevent knocking or not retard the ignition timing.

  In the memory of the ECU 0, the operating region of the internal combustion engine, that is, the engine speed and the accelerator opening (or the intake pressure in the surge tank 33, the intake amount or the fuel injection amount filled in the cylinder 1), and the ignition to the mixture are previously performed. Stored is map data defining the relationship with the timing (base value). The ECU 0 searches the map using the current engine speed and the accelerator opening as keys to know the ignition timing to be set. In addition, it is preferable to change the ignition timing by switching the map data to be referred to between when the fuel injection amount increase correction is executed and when it is not executed. Under the condition that the engine speed and the accelerator opening are equal, the ignition timing when the fuel injection amount increase correction is executed is equal to or more than the ignition timing when the increase correction is not executed. Advance.

  In addition, the specific configuration of each part, the content of processing, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 3 ... Intake passage 32 ... Throttle valve a ... Vehicle speed signal b ... Crank angle signal c ... Sensor output signal (accelerator opening signal) for detecting accelerator opening
e ... Intake temperature / intake pressure signal i ... Ignition signal j ... Fuel injection signal k ... Opening operation signal

Claims (3)

When the amount of increase in the accelerator opening per unit time exceeds the threshold value, the fuel injection amount increase correction is executed to enrich the air-fuel ratio of the air-fuel mixture filled in the cylinder as compared with the case where it is not. ,
A control apparatus for an internal combustion engine, wherein the threshold value when the accelerator opening is large is set lower than the threshold value when the accelerator opening is smaller. If the increase amount per unit time of the accelerator opening obtained by referring to the output signal of the sensor for detecting the accelerator opening exceeds the upper limit, it is based on the increase exceeding the threshold value. The control device for an internal combustion engine according to claim 1, wherein the increase correction is not executed. The control device for an internal combustion engine according to claim 1 or 2, wherein the threshold value when the vehicle speed of a vehicle on which the internal combustion engine is mounted as a power source for traveling is low is set lower than the threshold value when the vehicle speed is higher. .

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