JP2012211534A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of causing inconvenience such as a variation in an engine rotating speed of an internal combustion engine when an exhaust gas recirculating ratio temporarily rises by an operational delay in an exhaust gas recirculating device when reducing a speed.SOLUTION: The internal combustion engine includes the exhaust gas recirculating device having a recirculating passage for recirculating exhaust gas to an intake system and a recirculation control valve for controlling a quantity of the exhaust gas flowing in the recirculating passage, and an air volume control means for controlling the suction air volume. The control device of the internal combustion engine corrects a fuel injection quantity according to a response delay in the recirculation control valve when reducing the speed, and includes a target opening calculating means for calculating target opening of the recirculation control valve, an actual opening detecting means for detecting an actual opening of the recirculation control valve, an opening detecting means for detecting an actual opening of the air volume control means, and a fuel control means for increasing the fuel injection quantity when the detected actual opening is larger than the target opening of the recirculation control valve when reducing the speed when the suction air volume becomes minimum.

Description

  The present invention relates to an internal combustion engine that includes an exhaust gas recirculation device that recirculates a part of exhaust gas to an intake system in accordance with an operating state, and that controls the fuel injection amount when stopping the recirculation of exhaust gas during deceleration. The present invention relates to an engine control device.

  2. Description of the Related Art Conventionally, for example, an internal combustion engine mounted on an automobile is known to include an exhaust gas recirculation device for mixing a part of exhaust gas with intake air in order to improve fuel efficiency. For example, an exhaust gas recirculation device disclosed in Patent Document 1 includes an EGR passage that takes in a part of exhaust gas from an exhaust passage as exhaust recirculation gas (hereinafter referred to as EGR gas) and recirculates EGR gas to an intake passage. And an EGR valve that is disposed in the EGR passage and adjusts the amount of EGR gas flowing through the EGR passage.

  In such an exhaust gas recirculation device, at the time of deceleration, when the difference between the target opening of the EGR valve and the actual opening is larger than a predetermined value, fuel cut control for temporarily stopping fuel injection to the intake air It is controlled to speed up the execution time. During such operation, EGR gas is excessively increased due to a delay in response of the EGR valve, and the internal combustion engine may be misfired. However, there is no problem that misfire occurs by cutting the fuel before the internal combustion engine misfires. The speed is quickly reduced.

  However, in a state where the torque generated by the internal combustion engine is large, that is, in a state where the engine speed is high during deceleration, if the fuel cut timing is advanced, the torque (engine speed) rapidly decreases when the fuel cut is performed. Will do. As a result, a shock that lacks smoothness in the operating state of the internal combustion engine occurs due to such a decrease in torque, resulting in a decrease in drivability.

  Further, in order to prevent an excessive increase in EGR gas as described above, if the exhaust gas recirculation device is operated so that the amount of EGR gas decreases in an operating state other than during deceleration, the mixture gas The amount of EGR gas that occupies is reduced. As a result, the EGR rate, which is the ratio of the amount of EGR gas to the amount of intake air, decreases, resulting in a decrease in fuel consumption.

JP 2010-77898 A

  Therefore, the present invention pays attention to the above points, and eliminates problems such as fluctuations in the engine speed of the internal combustion engine when the exhaust gas recirculation rate temporarily increases due to the operation delay of the exhaust gas recirculation device during deceleration. The purpose is to plan.

  That is, the control device for an internal combustion engine of the present invention is an exhaust gas recirculation device in which the internal combustion engine includes a recirculation path for recirculating exhaust gas to the intake system and a recirculation control valve for controlling the amount of exhaust gas flowing through the recirculation path. And an air amount control means for controlling the intake air amount, and a control device for an internal combustion engine that corrects the fuel injection amount according to a response delay of the recirculation control valve at the time of deceleration, wherein the target opening of the recirculation control valve Target opening degree calculating means for calculating the actual opening degree of the reflux control valve, actual opening degree detecting means for detecting the actual opening degree of the air amount control means, and the intake air amount Fuel control means for increasing the fuel injection amount when the actual opening detected from the target opening of the reflux control valve is large at the time of the minimum deceleration is provided.

  According to such a configuration, even when the exhaust gas recirculation rate is increased when the recirculation control valve is operated with a delayed response to the input of the close signal at the time of deceleration at which the amount of intake air is minimized, Since the fuel control means increases the fuel injection amount, it is possible to increase the misfire limit, which is the limit for stopping the operation without igniting the air-fuel mixture. As described above, it is possible to prevent the occurrence of misfire by increasing the misfire limit, and it is possible to prevent the occurrence of a shock accompanying the above-described torque fluctuation and improve drivability. In addition, when the intake air amount is not the minimum, the exhaust gas recirculation rate can be increased, so that the fuel consumption can be improved.

  The present invention is configured as described above, and can increase the misfire limit. As a result, the exhaust gas recirculation rate can be increased in operating conditions other than during deceleration, so that fuel efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic structure explanatory drawing of the engine of embodiment of this invention. The flowchart which shows the control procedure of the embodiment. Action | operation explanatory drawing of the same embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  A multi-cylinder engine 100 schematically showing the configuration of one cylinder in FIG. 1 is mounted on an automobile, for example. The engine 100 includes an intake system 1 and an exhaust system 2. The intake system 1 is provided with a throttle valve 3 that opens and closes according to the amount of depression of an accelerator pedal (not shown), and an intake manifold 5 that integrally has a surge tank 4 is attached downstream of the throttle valve 3. The throttle valve 3 constitutes a so-called electronic throttle that operates a valve body by an electromagnetic actuator. The surge tank 4 is provided with an intake pressure sensor 22 for detecting the pressure in the surge tank 4 and hence the intake pipe pressure. In this embodiment, the throttle valve 3 constitutes an air amount control means.

A spark plug 8 is attached to the ceiling portion of the combustion chamber 7 formed in the upper part of the cylinder 6. A fuel injection valve 10 is attached to the intake port side end 9 of the intake manifold 5. The fuel injection valve 10 is controlled by an electronic control device 11 described later. Further, an exhaust gas recirculation device (hereinafter referred to as an EGR device) 15 is connected between the surge tank 4 and the exhaust system 2 including the O ₂ sensor 12, the three-way catalyst 13 and the exhaust manifold 14.

  The EGR device 15 is connected to an exhaust gas recirculation pipe (hereinafter referred to as EGR) having one end connected so as to communicate with the surge tank 4 and the other end connected to the exhaust passage 30 downstream of the three-way catalyst 13. And an exhaust gas recirculation control valve (hereinafter referred to as an EGR valve) 17 that is provided in the EGR pipe 16 and controls the flow rate of the exhaust gas that passes through the EGR pipe 16. Is done. The flow rate of the exhaust gas to be recirculated (hereinafter referred to as EGR gas) depends on the opening degree of the EGR valve 17, and the opening degree of the EGR valve 17 is controlled by the electronic control unit 11. The EGR valve 17 has a structure in which the valve body is moved by a stepping motor to control the amount of EGR gas.

  The electronic control device 11 includes a microcomputer 18, a memory 19, an input interface 20, and an output interface 21. The microcomputer 18 executes various programs described below stored in the memory 19 to control the operation of the engine 100. Information necessary for operation control of the engine 100 is input to the microcomputer 18 via the input interface 20, and the microcomputer 18 controls the fuel control valve 10, the EGR valve 17, the spark plug 8, and the like. Are output via the output interface 21.

Specifically, the input interface 20 detects the intake pressure signal a output from the intake pressure sensor 22, the rotation speed signal b output from the rotation speed sensor 23 for detecting the engine speed, and the vehicle speed. The vehicle speed signal c output from the vehicle speed sensor 24, the LL signal e output from the idle switch 25 for detecting the opening / closing state of the throttle valve 3, and the water temperature sensor 26 for detecting the cooling water temperature of the engine 100. The water temperature signal f and the voltage signal h output from the O ₂ sensor 12 are input. On the other hand, the output interface 21 outputs an ignition signal m to the spark plug 8, a fuel injection signal n to the fuel control valve 10, an open / close signal o to the EGR valve 17, and the like.

  In such a configuration, the electronic control unit 11 sets the intake pressure signal a output from the intake pressure sensor 22 and the rotation speed signal b output from the rotation speed sensor 23 as main information according to the driving state. The fuel injection amount is calculated using the coefficient to determine the fuel injection time corresponding to the fuel injection amount, that is, the energization time for the fuel injection valve 10, and the fuel injection valve 10 is controlled by the determined energization time, Fuel is injected into the intake system 1. Such fuel injection control itself may apply what is known in this field.

  Further, an EGR control program for controlling the opening degree of the EGR valve 17 and performing EGR control according to the operating state of the engine 100 is stored in the electronic control unit 11. This EGR control program may be widely known in this field.

  Further, the electronic control unit 11 stores a deceleration time control program for controlling the fuel injection amount at the time of deceleration when the EGR control is performed. This deceleration control program corrects the fuel injection amount based on the opening degree of the EGR valve 17 when the engine 100 is decelerated, and determines whether or not the throttle valve 3 is almost fully closed. When the opening degree is calculated, the actual opening degree of the EGR valve 17 is detected, and the deceleration time when the throttle valve 3 is almost fully closed is determined, the actual opening degree detected from the target opening degree of the EGR valve 17 is predetermined. The fuel injection amount is increased when it is determined whether the detected actual opening is greater than a target opening of the EGR valve 17 by a predetermined value or more. This deceleration control program is executed when the engine 100 is decelerating, and will be described below with reference to FIG.

  First, in step S1, it is determined whether or not the throttle valve 3 is almost fully closed. That is, it is determined whether or not the engine 100 is decelerating and the throttle valve 3 is almost fully closed, in other words, at the time of deceleration at which the amount of intake air is minimized. The minimum amount of intake air refers to the amount of intake air that can maintain the idle speed, and in the electronic throttle of this embodiment, the throttle valve 3 obtains the amount of intake air that can maintain the idle speed. From the fully closed state, the open state is maintained accordingly. By this step S1, an opening degree detection means is realized. In addition, in a thing provided with the idle rotation control apparatus provided with the detour which bypasses a throttle valve, and the flow control valve provided in the detour, a throttle valve is almost fully closed. This determination may determine that the operation amount (accelerator opening) of the accelerator pedal (accelerator grip) is 0, that is, the accelerator pedal is not operated. Thus, when determining the depression amount of an accelerator pedal, an accelerator pedal comprises an air quantity control means.

  In step S2, the target opening degree of the EGR valve 17 is calculated. The target opening is calculated based on the opening of the throttle valve 3 and the engine speed. When the throttle valve 3 is almost fully closed, the target opening is zero. By this step S2, the target opening calculation means is realized.

  In step S3, the actual opening of the EGR valve 17 is detected. The actual opening of the EGR valve 17 is detected based on the number of steps of the opening / closing signal of the EGR valve 17 when the throttle valve 3 is almost fully closed. That is, the throttle valve 3 is detected based on the number of steps of the opening / closing signal for the EGR valve 17 because the valve element is driven to open and close by the stepping motor. By this step S3, actual opening degree detection means is realized.

  In step S4, it is determined whether or not the difference between the detected actual opening and the target opening is equal to or greater than a predetermined value k. That is, this determination is to determine how much the response delay until the opening indicated by the opening / closing signal is actually reached after the EGR valve 17 receives the opening / closing signal is large. The predetermined value k increases the EGR rate, which is the ratio of the amount of EGR gas to the amount of intake air passing through the throttle valve 3 when the actual opening of the EGR valve 17 has not reached the target opening. Thus, the air-fuel ratio is set to be lean and set based on the difference between the target opening and the actual opening when the engine rotation becomes unstable.

  If it is determined in step S4 that the actual opening exceeds the target opening by a predetermined value k or more, the fuel injection amount is increased in step S5. That is, by increasing the fuel injection amount, the EGR rate increases and the air-fuel ratio becomes lean. This increase in the fuel injection amount ends when the opening of the EGR valve 17 is almost fully closed, and the air-fuel ratio is returned to the theoretical or target air-fuel ratio. That is, the fuel injection amount is increased only during a period corresponding to the time corresponding to the response delay of the EGR valve 17. If the accelerator pedal is depressed during the period when the fuel injection amount is being increased and acceleration operation is performed, the fuel injection amount is increased when the acceleration operation is started without waiting for the end of the period. Ends. By this step S5, the fuel control means is realized.

  In such a configuration, when the throttle valve 3 is almost fully closed when the engine 100 is decelerated, the intake air amount decreases. On the other hand, if the actual opening of the EGR valve 17 is larger than the target opening by a predetermined value k or more, the EGR gas continues to enter the surge tank 4 and the EGR rate increases. For this reason, the air-fuel ratio changes to the lean side, but the fuel injection amount is increased when the difference between the actual opening degree of the EGR valve 17 and the target opening degree is a predetermined value k or more. Therefore, as shown in FIG. 3, when the throttle valve 3 is almost fully closed, the opening of the EGR valve 17 is not the target opening, that is, the fully closed opening, and is more than the target opening. When the actual opening is larger than the predetermined value k, the air-fuel ratio is changed to the rich side while the EGR rate is increasing.

  As a result, even if the possibility of misfire increases due to an increase in the EGR rate, the misfire limit (indicated by a one-dot chain line in FIG. 3) can be increased by changing the air-fuel ratio to the rich side. it can. Therefore, misfire can be suppressed and a shock caused by a sharp decrease in torque can be prevented. For this reason, it is possible to suppress a decrease in drivability.

  Moreover, when the throttle valve 3 is open such as during deceleration, acceleration, and steady operation other than the above, it is not necessary to set the EGR rate low, and the fuel consumption in those operating states can be reduced. Can be suppressed. For this reason, a good fuel economy state can be maintained throughout the operation of engine 100.

  The present invention is not limited to the above embodiment.

  The actual opening of the EGR valve 17 may be, for example, a value obtained by directly measuring and converting the amount of movement of the valve body, or a value obtained by measuring the amount of EGR gas and converting it.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  Examples of utilization of the present invention include an internal combustion engine equipped with an exhaust gas recirculation device, such as an automobile, a motorcycle, and a marine motor, which may be in an idling state.

DESCRIPTION OF SYMBOLS 1 ... Intake system 3 ... Throttle valve 10 ... Fuel injection valve 11 ... Electronic control unit 15 ... Exhaust gas recirculation device 17 ... Exhaust gas recirculation control valve 16 ... Exhaust gas recirculation line 18 ... Microcomputer 19 ... Memory 20 ... Input interface 21 ... Output interface

Claims (1)

An exhaust gas recirculation device in which the internal combustion engine includes a recirculation path for recirculating the exhaust gas to the intake system and a recirculation control valve for controlling the amount of the exhaust gas flowing through the recirculation path, and an air amount control means for controlling the intake air amount And a control device for an internal combustion engine that corrects the fuel injection amount in response to a response delay of the reflux control valve during deceleration,
Target opening calculation means for calculating the target opening of the reflux control valve;
An actual opening detecting means for detecting the actual opening of the reflux control valve;
An opening degree detecting means for detecting an actual opening degree of the air amount control means;
A control device for an internal combustion engine, comprising: fuel control means for increasing a fuel injection amount when an actual opening detected from a target opening of the recirculation control valve is large during deceleration at which the intake air amount is minimized.

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