JP5333167B2 - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine in which, if fuel cut is executed in the internal combustion engine, information on the execution of fuel cut is displayed to the outside to prevent problems from being brought about in other vehicle control devices that are controlled in coordination with the internal combustion engine. <P>SOLUTION: If a precondition for executing fuel cut is satisfied, a remaining time before the fuel cut is executed is displayed. The displayed remaining time is calculated, during a time period in which a requested torque is larger than an idle torque, based on a torque difference between the idle torque and a FC execution torque. In the meantime, the displayed remaining time is calculated, during a time period in which the requested torque is decreased down to the idle torque, based on a torque difference between the FC execution torque and a target torque that gradually decreases at a prescribed rate from the idle torque. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly, to a control device that causes an internal combustion engine to perform a fuel cut when torque is reduced to a certain value.

  Conventionally, when the vehicle is driven by repulsion, the internal combustion engine performs a fuel cut. By cutting the fuel, wasteful fuel consumption can be suppressed. However, if the fuel cut is performed, the torque output from the internal combustion engine becomes zero in a stepwise manner, and a shock may occur depending on the magnitude of the torque output immediately before the fuel cut. In this regard, in the technique disclosed in Japanese Patent Application Laid-Open No. 2009-162185, the fuel cut is performed after the internal combustion engine reduces the torque to the minimum torque that can be output.

  The internal combustion engine is cooperatively controlled together with other vehicle control devices including a transmission. Since such cooperative control is necessary for optimizing the driving of the vehicle, cooperative control with other vehicle control devices is performed even when the fuel cut is performed. For example, Japanese Unexamined Patent Application Publication No. 2007-064477 and Japanese Unexamined Patent Application Publication No. 2005-163759 describe cooperative control with a transmission when a fuel cut is performed.

JP 2009-162185 A JP 2007-064477 A JP 2005-163759 A

  In the coordinated control with the transmission, the lockup is released according to the timing of the fuel cut in order to prevent the occurrence of torque shock. However, since it is necessary to operate the solenoid valve in advance to release the lockup, the lockup cannot be released suddenly. For this reason, even if the conditions for carrying out the fuel cut are satisfied, it cannot be carried out immediately, and it has been necessary to wait for the fuel cut to be carried out for the time required to release the lockup. Such a situation can also occur in cooperative control with a vehicle control device other than the transmission. In order to avoid the inconvenience caused by the fuel cut in the vehicle control device that is controlled in cooperation with the internal combustion engine, it is necessary to wait for the vehicle control device to be ready before performing the fuel cut. I don't get it.

  However, delaying the fuel cut causes unnecessary fuel consumption. Although it is desired to eliminate wasteful fuel consumption as much as possible, for this purpose, preparation on the vehicle control device side is required in advance so that it is not necessary to delay execution of fuel cut. However, in order to enable such an advance preparation, it is necessary to present information on the timing of the fuel cut to the vehicle control device side. In the conventional technology related to fuel cut, no examination has been made on how to generate and display such information.

  The present invention has been made in view of the above-described problems. When a fuel cut is performed in an internal combustion engine, the information related to the execution of the fuel cut is displayed outside and coordinated with the internal combustion engine. It is an object of the present invention to be able to avoid inconvenience in advance in the vehicle control device.

In order to achieve the above object, a control device for an internal combustion engine according to a first invention comprises:
Request torque acquisition means for acquiring torque required for the internal combustion engine (hereinafter referred to as request torque);
Means for determining whether a precondition for carrying out the fuel cut is satisfied;
While the required torque is larger than the predetermined fuel cut preparation reference torque, a target torque to be output to the internal combustion engine is set based on the required torque, and after the required torque is reduced to the fuel cut preparation reference torque, , Target torque setting means for gradually decreasing the target torque from the fuel cut preparation reference torque;
Fuel cut means for causing the internal combustion engine to perform fuel cut when the target torque is reduced to a predetermined fuel cut execution torque;
A remaining time display means for calculating and displaying the remaining time until the fuel cut is performed when the precondition is satisfied,
The remaining time display means calculates the remaining time from a torque difference between the fuel cut preparation reference torque and the fuel cut execution torque while the required torque is larger than the fuel cut preparation reference torque, Is reduced to the fuel cut preparation reference torque, the remaining time is calculated from the torque difference between the target torque and the fuel cut execution torque.

A control device for an internal combustion engine according to a second invention is the control device for an internal combustion engine according to the first invention,
Target torque gradual reduction rate changing means for changing the gradual decrease rate of the target torque by the target torque setting means according to an external request;
Is further provided.

A control device for an internal combustion engine according to a third invention is the control device for an internal combustion engine according to the first invention,
Prohibiting means for prohibiting the execution of the target torque by the target torque setting means and the execution of the fuel cut by the fuel cut means in response to an external request;
Is further provided.

  According to the control apparatus for an internal combustion engine of the first invention, when the precondition for performing the fuel cut is satisfied, the remaining until the fuel cut is performed until the fuel cut is performed thereafter. The time is displayed. The remaining time to be displayed is calculated from the torque difference between the fuel cut preparation reference torque and the fuel cut execution torque while the required torque is larger than the fuel cut preparation reference torque. The remaining time calculated during this time means a time that can be surely secured even if the target torque starts to gradually decrease. Then, after the required torque is reduced to the fuel cut preparation reference torque, it is calculated from the torque difference between the target torque that gradually decreases from the fuel cut preparation reference torque at a predetermined speed and the fuel cut execution torque. The remaining time calculated during this time means the exact remaining time until the fuel cut is performed. By displaying such remaining time toward the outside, other vehicle control devices that are coordinated with the internal combustion engine can start measures for fuel cuts in accordance with the displayed remaining time. It becomes.

  According to the control apparatus for an internal combustion engine of the second aspect of the invention, if the measure for fuel cut by another vehicle control device is not in time as judged from the displayed remaining time, the gradual decrease rate of the target torque is delayed. By this, the remaining time can be extended urgently. As a result, it is possible to reliably prevent the measures for fuel cut from being in time for other vehicle control devices.

  According to the control apparatus for an internal combustion engine of the third aspect of the present invention, if the countermeasure for the fuel cut by another vehicle control device is not in time as judged from the displayed remaining time, the target torque is gradually reduced. Subsequent fuel cuts can be urgently canceled. Thus, it is possible to reliably prevent the fuel cut from being performed on the internal combustion engine side even though the preparation on the other vehicle control device side is not complete.

It is a block diagram which shows the control system of the vehicle of embodiment of this invention. It is a time chart for demonstrating the content of the control before FC concerning the embodiment of this invention, and the calculation method of the remaining time to FC. It is a flowchart which shows the calculation procedure of the remaining time concerning embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

  FIG. 1 is a block diagram showing a vehicle control system of the present embodiment. The vehicle control system of the present embodiment is positioned above the engine controller that directly controls the internal combustion engine (hereinafter referred to as the engine), the transmission controller that directly controls the transmission, and the engine controller and the transmission controller. The vehicle controller is configured to comprehensively control the entire vehicle. Although other vehicle control devices are also connected to the vehicle controller, only the transmission and the transmission controller will be described here for explanation.

  The arrow lines shown in FIG. 1 indicate the flow of information in the control system. The required torque for the engine is supplied from the vehicle controller to the engine controller. This required torque includes a required torque from a vehicle control device such as a transmission, VSC, TRC, etc., in addition to a driver required torque calculated from the opening of the accelerator pedal. The engine controller sets a target torque to be output to the engine based on the acquired required torque. Then, the operation amount of each actuator of the engine is determined from the target torque, and a command signal for operating each actuator is supplied to the engine. Typical examples of the actuator include an ignition device and a throttle when the engine is of a spark ignition type.

  On the other hand, information indicating the operating state of the engine is supplied from the engine to the engine controller. Such information is acquired by various sensors attached to the engine body and its surroundings. In addition to information indicating the engine operating state, information indicating the engine control status is also supplied from the engine controller to the vehicle controller.

  The same information exchange as in the engine control system is also performed between the vehicle controller and the transmission controller, and between the transmission controller and the transmission. That is, a control signal and an operation signal are supplied from the vehicle controller to the transmission, and information indicating a driving state and a control state is supplied from the transmission to the vehicle controller.

  In FIG. 1, in addition to the arrow lines indicating the flow of information, the contents relating to a part of the information are displayed. The content shown in FIG. 1 is exchanged in the control system when a fuel cut (more specifically, a fuel cut performed when the idle switch is turned on) is performed in the engine. Information. As can be inferred from the flow of information, in the vehicle control system of the present embodiment, when fuel is cut in the engine, the fuel is not only supplied to the engine control system but also to the transmission control system. Information about the implementation of cuts is provided. Hereinafter, the contents of information exchanged in the control system will be described with reference to a time chart together with the description of the engine control performed before and after the fuel cut.

  In the time chart of FIG. 2, a target torque set by the engine controller is shown in the upper part. In addition, a curve indicating idle torque and a curve indicating FC execution torque are listed together. The idle torque is a torque required for idling the engine, and its value varies depending on the engine operating conditions. The engine controller performs idle torque calculation at a constant control cycle based on the current engine operating conditions. The FC execution torque is a torque when it is determined that the fuel cut is to be executed. In this embodiment, the FC execution torque is set to the minimum torque that the engine can output. Since the minimum torque value varies depending on the engine operating conditions, the engine controller calculates the FC execution torque at a constant control cycle based on the current engine operating conditions.

  The engine controller compares the required torque supplied from the vehicle controller with the idle torque. While the required torque is greater than the idle torque, the target torque is set based on the required torque. Accordingly, when the required torque includes a fluctuation component, the target torque also fluctuates due to the influence of the fluctuation component as shown in the figure. After the required torque decreases to the idle torque, the engine controller gradually decreases the target torque from the idle torque at a constant speed. In the figure, it is shown that the amount of torque reduction in the unit time TQTIME is TQDWN. Although illustration is omitted, on the engine side, the throttle is closed so as to gradually reduce the target torque, and further, the ignition timing is retarded. Eventually, when the target torque decreases to the FC execution torque, the engine controller causes the engine to perform fuel cut. In that case, the target torque of the engine is zero.

  In the middle part of the time chart of FIG. 2, the setting of two types of flags is shown. The FC precondition flag is a flag indicating whether or not a precondition for performing the fuel cut is satisfied. The precondition is a condition for performing fuel cut without causing inconvenience in driving the vehicle. For example, the idle switch is on, the brake is off, and the vehicle speed is below a predetermined value. Etc. are included in the preconditions. The engine controller determines whether the precondition is satisfied, and sets the FC precondition flag to ON when the precondition is satisfied.

  The pre-FC control execution flag is a flag that is turned on when the required torque decreases to the idle torque. When the pre-FC control execution flag is turned on, the target torque is gradually reduced at a constant speed as described above. The engine controller displays the FC precondition flag ON / OFF and the pre-FC control execution flag ON / OFF for the vehicle controller. Hereinafter, the control region from when the FC precondition flag is turned on to when the pre-FC control execution flag is turned on is referred to as the pre-FC control standby region. After the pre-FC control execution flag is turned on, the fuel cut is actually performed. The control area until execution is called a pre-FC control execution area.

  The lower part of the time chart in FIG. 2 shows the remaining time calculated by the engine controller. The remaining time here is the remaining time until the fuel cut is performed. As shown in the figure, the remaining time is normally set to an invalid maximum value (MAX), and calculation of a valid value is started when the FC precondition flag is turned ON. When the fuel cut is performed, the remaining time is returned to the maximum value (MAX) again.

  The calculation of the remaining time is performed by a method corresponding to the control region. In the pre-FC control execution area, the target torque is gradually reduced at a constant speed toward the FC execution torque. Therefore, the remaining time can be accurately calculated by calculating the torque difference (indicated by B in the figure) between the target torque and the FC execution torque and dividing the torque difference B by the target torque reduction rate.

  On the other hand, in the pre-FC control standby region, the target torque is set based on the required torque. Since the required torque is a sum of required torques from various vehicle control devices, the trajectory is not necessarily constant. Therefore, the change in the target torque in the pre-FC control standby region is not constant, and the remaining time cannot be simply calculated from the torque difference between the target torque and the FC execution torque. Accordingly, the estimated remaining time is calculated by calculating the torque difference (indicated by A in the figure) between the idle torque and the FC execution torque, and dividing the torque difference A by the target torque reduction rate in the pre-FC control execution area. Calculate

  FIG. 3 is a flowchart showing the remaining time calculation procedure described above. In the first step S2, it is determined whether or not the FC precondition flag is on and whether or not the fuel cut is being performed. Only when the FC precondition flag is ON and the fuel cut is not being performed, the routine proceeds to step S4 and the next determination is made. If the FC precondition flag is still off, the remaining time is maintained at the maximum value (MAX) in step S12.

In step S4, it is determined whether the pre-FC control execution flag is on. When the pre-FC control execution flag is off, that is, when the current control area is in the pre-FC control standby area, the process of step S10 is performed through step S6. On the other hand, when the pre-FC control execution flag is on, that is, when the current control area is in the pre-FC control execution area, the process of step S10 is performed through step S8. In step S10, the remaining time is calculated by the following equation.
Remaining time = (X / TQDWN) × TQTIME

  In the above formula, TQTIME is a unit time, and TQDWN is a torque reduction amount per unit time. These are fixed values, and the values correspond to the gradual decrease speed of the target torque in the pre-FC control. X is a torque difference with respect to the FC execution torque, and its value is determined in step S6 or S8.

  In step S6, the torque difference A between the idle torque and the FC execution torque is selected as the torque difference X. If the current control area is in the pre-FC control standby area, the remaining time is calculated from the torque difference A in step S10. The remaining time calculated in this way means the time until the fuel cut that can be surely secured even if the pre-FC control is started immediately and the target torque starts to gradually decrease.

  In step S8, the torque difference B between the target torque and the FC execution torque is selected as the torque difference X. If the current control region is in the pre-FC control execution region, the remaining time is calculated from the torque difference B in step S10. The remaining time calculated in this way means an accurate remaining time until the fuel cut is performed.

  The engine controller displays the remaining time calculated by the above method for the vehicle controller. The vehicle controller supplies the remaining time received from the engine controller to the transmission controller together with a fuel cut notice. As a result, the transmission controller side can start measures against fuel cut, specifically, release of lockup of the transmission in accordance with the displayed remaining time.

  If the time required for unlocking the transmission is shorter than the displayed remaining time, it may not be possible to release the lockup in time for the fuel cut. Accordingly, the transmission controller requests the vehicle controller to change the torque control when the lockup release of the transmission is not in time as judged from the displayed remaining time. Upon receiving the request, the vehicle controller instructs the engine controller to delay the gradual decrease rate of the target torque in the pre-FC control. The remaining time until the fuel cut can be urgently extended by delaying the gradual decrease rate of the target torque, specifically, by reducing the value of TQDWN. As a result, it is possible to reliably prevent the release of the lockup of the transmission from being in time for the fuel cut.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, as a countermeasure when the unlocking of the transmission is not in time for the fuel cut, the fuel cut may be canceled. In this case, the vehicle controller that receives the request from the transmission controller prohibits the engine controller from performing pre-FC control and fuel cut. As a result, it is possible to reliably prevent the fuel cut from being performed on the engine side even though the transmission side is not ready.

Claims (3)

Request torque acquisition means for acquiring torque required for the internal combustion engine (hereinafter referred to as request torque);
Means for determining whether a precondition for carrying out the fuel cut is satisfied;
While the required torque is larger than the predetermined fuel cut preparation reference torque, a target torque to be output to the internal combustion engine is set based on the required torque, and after the required torque is reduced to the fuel cut preparation reference torque, , Target torque setting means for gradually decreasing the target torque from the fuel cut preparation reference torque;
Fuel cut means for causing the internal combustion engine to perform fuel cut when the target torque is reduced to a predetermined fuel cut execution torque;
A remaining time display means for calculating and displaying the remaining time until the fuel cut is performed when the precondition is satisfied,
The remaining time display means calculates the remaining time from a torque difference between the fuel cut preparation reference torque and the fuel cut execution torque while the required torque is larger than the fuel cut preparation reference torque, Is reduced to the fuel cut preparation reference torque, the remaining time is calculated from a torque difference between the target torque and the fuel cut execution torque. Target torque gradual reduction rate changing means for changing the gradual decrease rate of the target torque by the target torque setting means according to an external request;
The control device for an internal combustion engine according to claim 1, further comprising: Prohibiting means for prohibiting the execution of the target torque by the target torque setting means and the execution of the fuel cut by the fuel cut means in response to an external request;
The control device for an internal combustion engine according to claim 1, further comprising:

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