JP5812620B2 - Method for controlling idle speed of internal combustion engine - Google Patents

Description

  The present invention relates to an idle speed control method for an internal combustion engine in which feedback control is performed on an intake air amount at least during idle operation.

  Conventionally, for example, in an internal combustion engine mounted in an automobile or the like, idle speed control is generally used in which an intake air amount is feedback-controlled during idle operation so that the engine speed is controlled to become an idle target speed. In this type of idling engine speed control, in order to improve the convergence to the idling target engine speed, the feedback correction amount for correcting the intake air amount is set to an electric power for an internal combustion engine having a predetermined condition, for example, with little disturbance. It is configured to learn when there is no load.

  In the configuration in which learning of the feedback correction amount learning value is executed only when there is no electric load, learning may be difficult depending on the region where the automobile is used. That is, for example, when an air conditioner (hereinafter referred to as an air conditioner) is almost always used while a car is used, the engine is always in an electrical load state, so there is no opportunity to perform learning. . Accordingly, since an appropriate learning value cannot be obtained, idle rotation may become unstable in idle rotation control. In addition, when the opportunity to learn the learning value of the feedback correction amount decreases in this way, deposits adhere to the idle speed control device including the flow control valve that controls the intake air amount during idle operation due to aging. The difference between the required feedback correction amount and the learning value may widen.

  In Patent Document 1, the feedback correction amount during the feedback control is already stored so that the increase in the feedback correction amount due to such a change in flow rate due to the secular change and the disturbance such as the electric load is corrected and the idle rotation is stabilized. When the learning value is different from the learning value, the learning value is corrected with a correction value corresponding to the difference between the idle speed and the target idling speed, and the corrected result is stored as a new learning value. ing. However, in the case of this Patent Document 1, even if there is an electric load, for example, if there is no difference between the feedback correction amount and the learning value, learning is not executed.

  By the way, generally, when learning of the feedback correction amount in the idle rotation control when there is an electric load, a value including the electric load is learned. For this reason, depending on the change of the electric load, when the idle rotation speed control is executed using the learned value learned thereafter, the idle rotation becomes unstable. In consideration of such a problem, when an electric load amount is detected, and a learning value learning is performed by subtracting the intake air amount corresponding to the detected electric load amount from the feedback correction amount, A means for detecting the load amount is required. This complicates the system configuration and increases the manufacturing cost.

JP 58-158343 A

  Accordingly, the present invention focuses on the above points and aims to stabilize the idle rotation by executing learning of the learning value even when there is an electric load without detecting the electric load.

That is, the idle speed control method for an internal combustion engine according to the present invention performs feedback control of the intake air amount during idle with the feedback correction amount so that the engine speed of the internal combustion engine becomes the target idle speed during idling of the internal combustion engine. An idle speed control method for an internal combustion engine that learns a learned value of a feedback correction amount when a predetermined condition is satisfied, and determines whether or not there is an electrical load on the internal combustion engine, and learns if there is an electrical load The feedback control is executed from the feedback correction amount obtained by adding a predetermined value to the value, and the amount of change in the feedback correction amount changes beyond the determination value for the learning determination during the feedback control when it is determined that there is an electric load. If the is intended to carry out learning of the learning value, the learning value for learning, the amount exceeding the determination value of the change amount Characterized in that it is a sum of the times of the learning value. In addition, the idle speed control method for an internal combustion engine according to the present invention feedback-controls the intake air amount during idling with a feedback correction amount so that the engine speed of the internal combustion engine becomes the target idle speed during idling of the internal combustion engine. An idle speed control method for an internal combustion engine that learns a learned value of a feedback correction amount when a predetermined condition is satisfied, and determines whether or not there is an electrical load on the internal combustion engine, and learns if there is an electrical load The feedback control is executed from the feedback correction amount obtained by adding a predetermined value to the value, and the amount of change in the feedback correction amount changes beyond the determination value for the learning determination during the feedback control when it is determined that there is an electric load. The learning value is learned in this case, and the judgment value is the feedback correction amount when there is no electrical load. Set by the difference between the first judgment value set by the difference between the feedback correction amount when the air load is maximum and the feedback correction amount when there is no electric load and the feedback correction amount when the electric load is minimum The learning value is updated when the change amount increases beyond the first determination value and when the change amount decreases beyond the second determination value.

  According to such a configuration, the feedback control is executed with the feedback correction amount corresponding to the electric load without detecting the magnitude of the electric load, and learning is performed when the change amount of the feedback correction amount exceeds the determination value during that time. As a result, the learning value can be learned even when the electric load is constantly applied to the internal combustion engine.

  The present invention is configured as described above, and in a region where the electric load is constantly applied to the internal combustion engine, the learning value is learned in a timely manner without using a means for detecting the electric load. be able to.

The figure which shows the structure of the engine 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 implements.

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

  The engine 100 schematically shown in FIG. 1 is for an automobile, and an automobile equipped with the engine 100 is equipped with an air conditioner that operates using the output of the engine 100 as a driving force. The air conditioner itself may be well known in the art, and includes a compressor that compresses the cooling medium, and the compressor operates by receiving a driving force from the engine when an electromagnetic clutch is connected, for example. Configured as follows.

  The engine 100 is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown) in the intake system 1 and a bypass passage 3 that bypasses the throttle valve 2. The bypass passage 3 is provided with a flow rate control valve 4 for controlling the idle speed. The flow rate control valve 4 is an electromagnetic open / close type abbreviated as a large flow rate VSV that can collectively realize various correction items such as start-up correction and water temperature correction. It constitutes a control device. In addition to this, a fuel injection valve 5 is further provided in the vicinity of the intake port 10 constituting the intake system 1. The fuel injection valve 5 and the flow rate control valve 4 are controlled by an electronic control unit 6.

  The flow rate control valve 4 can change the opening degree per unit time by controlling the calculation duty ratio DISC of the applied drive voltage, and thereby the flow rate of air flowing through the bypass passage 3 can be adjusted. ing. That is, a set of the bypass passage 3 and the flow control valve 4 unifies the bypass system path provided for each correction item in the feedback control at the time of idling. The calculation duty ratio DISC includes these items and corresponds to each correction amount. For example, the correction items such as the start time correction coefficient DSTA, the water temperature correction coefficient DAAV, the air conditioner correction coefficient ACC, and the feedback correction coefficient DFB are added together. The variable range is limited so as not to become extremely large or small. In addition, as will be described later, the feedback correction coefficient DFB corresponding to the feedback correction amount is stored as a learning value DFBRAC when a predetermined condition is satisfied.

  The electronic control device 6 is mainly configured by a microcomputer system including a central processing unit 7, a storage device 8, an input interface 9, and an output interface 11. The input interface 9 detects the engine speed NE including the intake pressure signal a output from the intake pressure sensor 13 for detecting the pressure in the surge tank 12 constituting the intake system 1 and the idle speed. A rotation speed signal b output from the rotation speed sensor 14, a vehicle speed signal c output from the vehicle speed sensor 15 for detecting the vehicle speed, and an opening degree output from the throttle sensor 16 for detecting the open / closed state of the throttle valve 2. The signal d, the water temperature signal e output from the water temperature sensor 17 for detecting the engine coolant temperature as the engine temperature, the on / off signal output from the operation switches of various electric loads including the air conditioner, and the like are input. . Further, a drive signal f corresponding to the calculated fuel injection time is output from the output interface 11 to the fuel injection valve 5, and a control signal having a calculated duty ratio DISC described later is supplied to the flow rate control valve 4. An ignition signal g is output to the spark plug 18 and a control signal is output to the electromagnetic clutch of the air conditioner. Although not shown, the electronic control unit 6 includes an A / D converter for converting an input analog signal into digital data, and the analog temperature signal e.g. The data is converted into data and output to the central processing unit 7.

  The electronic control unit 6 determines the fuel injection valve opening time (fuel injection amount) using the intake pressure signal a and the rotation speed signal b from the intake pressure sensor 13 and the rotation speed sensor 14 as main information, and the fuel is determined by the determination. A program for controlling the injection valve 5 and injecting fuel corresponding to the load from the fuel injection valve 5 to the intake system 1 is incorporated. Further, the opening degree of the flow rate control valve 4 provided in the bypass passage 3 that bypasses the throttle valve 2 corresponds to the calculated duty ratio DISC calculated based on various correction coefficients that are appropriately set according to the operating state. Control is performed by the control signal g, and the air flow rate to the intake system 1 is adjusted so that the engine speed during idling, that is, the idle speed NE is set to the target speed.

  In this idle speed control, that is, idle speed control, it is determined whether or not there is an electrical load on the engine 100. If it is determined that there is an electrical load, feedback control is performed from a feedback correction coefficient DFB obtained by adding a predetermined amount to the learning value DFBRAC. A feedback correction coefficient that performs learning of the learning value DFBRAC when the amount of change in the feedback correction coefficient DFB changes beyond a determination value for learning determination during feedback control when it is determined that there is an electrical load. A DFB learning control program is provided.

  As correction coefficients other than the feedback correction coefficient DFB such as the start-time correction coefficient DSTA and the water temperature correction coefficient DAAV, those known in this field can be applied, and the description thereof will be omitted.

  A schematic configuration of a control program for the feedback correction coefficient DFB of this embodiment is shown in FIG. The feedback correction coefficient DFB is set to an initial value, for example, and after the engine 100 is started, a predetermined operation state, for example, the engine temperature (cooling water temperature) is equal to or higher than the predetermined temperature, and the engine speed is equal to or higher than the predetermined speed. When the operation state where the feedback control condition such as is satisfied is established, control is performed so that the idling engine speed becomes the target idling engine speed starting from the set initial value. In addition, after learning the feedback correction coefficient DFB, when the idling operation state is canceled and then the idling operation state is resumed, the feedback correction coefficient DFB uses the learning value DFBRAC stored at that time as an initial value. Then, idle speed control is executed.

  In this embodiment, when learning the feedback correction coefficient DFB in the idle speed control, the above-described determination value is set as follows. That is, the determination value includes the first determination amount set by the difference between the feedback correction coefficient DFB when there is no electric load and the feedback correction coefficient DFB when the electric load is maximum, and the feedback correction coefficient when there is no electric load. The second determination amount is set based on the difference between the DFB and the feedback correction coefficient DFB when the electric load is minimum.

  The learning procedure of the feedback correction coefficient DFB in this embodiment will be described with reference to FIG. The flowchart shown in FIG. 2 is executed when the engine is in the idle operation state, and when the accelerator pedal is operated during the idle operation, the learning control of the learning value is stopped. Further, the learning of the feedback correction coefficient DFB when there is no electric load can be performed using the same configuration as the conventional one, and the description is omitted.

  In FIG. 2, in step S1, it is determined whether there is an electrical load. Specifically, it determines whether or not the air conditioner, headlight, electric motor, etc. are energized from the state of the operation switch of those electric loads. When it is detected that the operation switch is on, the electric load It is determined that there is.

  If it is determined that there is an electric load, in step S2, a predetermined value is added to the learned value DFBLAC of the feedback correction coefficient DFB stored at this time, and the feedback correction coefficient DFB in the idle rotation control at this time is set. . The predetermined value is set in advance and is not changed during idle rotation control. For example, the predetermined value is set to several percent when the opening degree of the flow control valve 4 is 100%.

In step S3, feedback control is performed using the set feedback correction coefficient DFB as an initial value so that the idle speed converges to the target speed.

  In step S4, it is determined whether or not the amount of change when the feedback correction coefficient DFB is changed by feedback control, that is, the difference between the learning value DFBLAC and the feedback correction coefficient DFB at this time exceeds the first determination value. The first determination value is set by the difference between the feedback correction coefficient DFB when there is no electric load and the feedback correction coefficient DFB when the electric load is maximum. This first determination value is for determining whether or not to perform learning when the feedback correction coefficient DFB increases. When the amount of change increases beyond the first determination value, it is determined that the first determination value has been exceeded.

  In step S5, the total value of the predetermined value and the first determination value is subtracted from the feedback correction coefficient DFB at this time, and the resulting value is stored (updated) as a learning value. In other words, the learning value DFBLAC when feedback control of the feedback correction coefficient DFB is started, that is, the learning value DFBRAC before the current learning, and the change amount of the feedback correction coefficient DFB after the start of feedback control are used as the first determination value. The value obtained as a result of summing the value obtained by subtracting the value is updated as the current learning value DFBLAC.

  In step S6, it is determined whether or not the amount of change in the feedback correction coefficient DFB exceeds the second determination value. The second determination value is set by the difference between the feedback correction coefficient DFB when there is no electric load and the feedback correction coefficient DFB when the electric load is minimum. This second determination value is for determining whether or not learning is performed when there is an electrical load and the feedback correction coefficient DFB decreases. When the feedback correction coefficient DFB decreases and the amount of change decreases to the second determination value or more, it is determined that the second determination value has been exceeded.

  In step S7, the total value of the predetermined value and the second determination value is subtracted from the feedback correction coefficient DFB at this time, and the resulting value is stored (updated) as the learning value DFBRAC.

In such a configuration, for example, when the idling operation is performed while using the air conditioner, there is an electric load during the idling operation, so steps S1 to S3 are executed, and a predetermined value is set to the learning value stored at this time. In addition, idle speed control is performed as an initial value of the feedback correction coefficient DFB when there is an electric load. Then, in the process of performing the idle speed control, the actual electric load is larger than expected with a predetermined value, and the feedback correction coefficient DFB is increased, and the amount of change exceeds the first determination value. Until then, the learning of the feedback correction coefficient DFB learning value DFBLAC is not performed (“No” in step S4) . On the other hand, the learning value DFBLAC is not learned until the actual electrical load is smaller than expected at the predetermined value, the feedback correction coefficient DFB changes to the decreasing side, and the amount of change exceeds the second determination value (step in S 6 "No").

As described above, the first determination value and the second determination value are set so that it can be determined that the feedback correction coefficient DFB has reliably changed to the increase side and the decrease side, and the engine 100 is temporarily loaded. When the feedback correction coefficient DFB changes, it is prohibited to learn the value. That is, while the amount of change in the feedback correction coefficient DFB is less than the first determination value and the second determination value, the feedback correction coefficient DFB is not learned no matter how the feedback correction coefficient DFB changes. Thereby, it is possible to eliminate learning of a transient change of the feedback correction coefficient DFB, and it is possible to suppress an unstable change of the learning value.

When the change amount of the feedback correction coefficient DFB increases beyond the first determination value, and when the change amount of the feedback correction coefficient DFB decreases beyond the second determination value, the feedback correction coefficient DFB at that time is changed. Based on this, the learning value DFBRAC is updated (step S5, step S7).

  Therefore, learning of the feedback correction coefficient DFB is performed in a state where the electric load is present without detecting the electric energy of the electric load even when the automobile is used in an area where the electric load is always applied to the engine. Can do. Therefore, since a means for detecting the electric energy of the electric load is not necessary, the manufacturing cost can be suppressed despite the improvement of the learning function in the idle rotation control.

  Moreover, since the change of the feedback correction coefficient DFB for updating the learning value is determined by the first determination value and the second determination value, when the state of the deposit attached to the bypass passage 3 or the flow control valve 4 changes. The change can be reflected in the learning value.

  The present invention is not limited to the above embodiment.

  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.

  As an application example of the present invention, there is an internal combustion engine that is considered to be in a use state in which an electric load such as an air conditioner is constantly applied to the internal combustion engine.

3 ... Bypass passage 4 ... Flow control valve 6 ... Electronic control unit

Claims (2)

The idle intake air amount is feedback-controlled by the feedback correction amount so that the engine rotational speed of the internal combustion engine becomes the idle target rotational speed during the idling operation of the internal combustion engine, and the learning value of the feedback correction amount is set when a predetermined condition is satisfied. An idle speed control method for an internal combustion engine to be learned,
Determine if there is an electrical load on the internal combustion engine,
When it is determined that there is an electrical load, feedback control is executed from the feedback correction amount obtained by adding a predetermined value to the learning value,
Learning value learning is performed when the amount of change in the feedback correction amount changes beyond the determination value for determination of learning during feedback control when it is determined that there is an electrical load .
The learning value to be learned is an idling speed control method for an internal combustion engine, which is a total value of an amount exceeding a determination value of the change amount and a previous learning value . The idle intake air amount is feedback-controlled by the feedback correction amount so that the engine rotational speed of the internal combustion engine becomes the idle target rotational speed during the idling operation of the internal combustion engine, and the learning value of the feedback correction amount is set when a predetermined condition is satisfied. An idle speed control method for an internal combustion engine to be learned,
Determine if there is an electrical load on the internal combustion engine,
When it is determined that there is an electrical load, feedback control is executed from the feedback correction amount obtained by adding a predetermined value to the learning value,
Learning value learning is performed when the amount of change in the feedback correction amount changes beyond the determination value for determination of learning during feedback control when it is determined that there is an electrical load.
The determination value is a first determination value set by the difference between the feedback correction amount when there is no electric load and the feedback correction amount when the electric load is maximum,
It consists of a second determination value set by the difference between the feedback correction amount when there is no electric load and the feedback correction amount when the electric load is minimum,
An idle speed control method for an internal combustion engine , wherein the learning value is updated when the amount of change increases beyond a first determination value and when the amount of change decreases beyond a second determination value .

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