JP2009250071A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel economy by increasing an operation range in which fuel cut is executed. <P>SOLUTION: Fuel cut is executed while brake operation is performed in such a state that acceleration operation is not performed. If the brake operation is canceled during the execution of the fuel cut, the fuel cut is continued while it is determined that vehicle vibration may be generated, and when it is determined that there is no possibility of the generation of vehicle vibration, the fuel cut is stopped and fuel injection is restarted. However, when the brake operation is canceled during the execution of the fuel cut, in the case that a demand for acceleration by a driver is great, the fuel cut is immediately stopped and the fuel injection is restarted even if it is determined that vehicle vibration may be generated. Furthermore, it is determined whether or not an engine 11 can be started only by the restart of the fuel injection. When it is determined that it is difficult to start the engine 11 only by the restart of the fuel injection, a starter 22 is driven for starting the engine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device equipped with a function for automatically stopping and starting an internal combustion engine (engine).

  In recent years, vehicles equipped with an automatic engine stop / start system (so-called idle step system) have been put into practical use for the purpose of reducing fuel consumption and exhaust emissions. In general, the idle step system is such that when the driver performs a stop operation (release of accelerator operation, brake operation, etc.) in an idle operation state where the vehicle is almost stopped, the automatic stop condition is satisfied and the fuel is cut. When the engine is automatically stopped and the driver performs a preparation operation (release of brake operation, shift lever operation, etc.) or start operation (accelerator depression, etc.) for vehicle start during this automatic stop, the automatic start condition is Once established, the fuel injection is restarted and automatically started.

Such an idle step system is often mounted on a vehicle with an automatic transmission, but is described in Patent Document 1 (Japanese Patent Laid-Open No. 2000-144718) and Patent Document 2 (Japanese Patent Laid-Open No. 11-257118). As shown in the figure, the idle step system may be mounted on the vehicle of the manual mission.
JP 2000-144718 A JP-A-11-257118

  Each of the above conventional idle stop systems is a technology that stops the engine by executing fuel cut under predetermined conditions while the vehicle is stopped. However, if the fuel cut is executed only when the vehicle is stopped, the fuel efficiency can be improved. There is a limit.

  In general, during vehicle deceleration, the fuel cut during deceleration is performed until the rotation speed of the internal combustion engine decreases to the fuel cut return rotation speed during deceleration, and the rotation speed of the internal combustion engine decreases below the fuel cut return rotation speed during deceleration. At that time, the fuel injection is resumed after returning from the fuel cut during deceleration. Even after the fuel cut during deceleration is restored, the driver may operate the brake without performing the accelerator operation (that is, when the driving force of the internal combustion engine is not required). In order to resume the fuel injection after restarting, the combustion torque of the internal combustion engine is consumed by the brake operation, and the fuel is consumed wastefully.

  The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that can improve the fuel efficiency by expanding the operating range in which the fuel cut is executed.

  In order to achieve the above object, an invention according to claim 1 is directed to a clutch for connecting / releasing a path for transmitting the power of an internal combustion engine to a drive system, a fuel cut under a predetermined automatic stop condition, and from the fuel cut state. In an internal combustion engine control device applied to a vehicle provided with an automatic stop start control means for restarting fuel injection under a predetermined automatic start condition, an accelerator operation detection means for detecting an accelerator operation, and a brake operation for detecting a brake operation The automatic stop / start control means is configured to perform fuel cut during a period in which the brake operation is performed in a state where the accelerator operation is not performed.

  In general, a state in which the driver performs a brake operation (brake depression) without performing an accelerator operation (accelerator depression) means that the driver does not need the driving force of the internal combustion engine. In normal fuel cut control during deceleration, when the rotational speed of the internal combustion engine drops below the fuel cut return rotational speed during deceleration, the fuel cut is resumed and fuel injection resumes. There are cases where the brake operation is performed without performing the accelerator operation (that is, when the driving force of the internal combustion engine is not required). Even in such a case, when the fuel injection is resumed after returning from the fuel cut, the combustion torque of the internal combustion engine is consumed by the brake operation, and the fuel is consumed wastefully.

  Therefore, the present invention performs a fuel cut during a period in which the brake operation is performed in a state where the accelerator operation is not performed, and thereby, the internal combustion engine even in a region below the conventional fuel cut return rotational speed during deceleration. The fuel cut can be executed when the driving force is not required, and fuel efficiency can be improved.

  By the way, when the brake operation is canceled during the fuel cut, the fuel injection is usually resumed after the fuel cut is resumed. Depending on the state of the transmission and the rotation state of the drive system, when fuel injection is resumed, there is a possibility that vehicle vibration may occur.

  As a countermeasure against this, the vehicle vibration determination means for determining whether or not there is a possibility of vehicle vibration as in claim 2 is provided, and the vehicle vibration is detected when the brake operation is released during the fuel cut. The fuel cut is continued during a period in which it is determined that the vehicle vibration may occur by the determination means, and when there is no longer a possibility of the vehicle vibration occurring, the fuel injection is resumed after the fuel cut is resumed. May be. In this way, it is possible to prevent vehicle vibration from occurring when the fuel cut is restored.

  In this case, as in claim 3, it may be determined whether or not there is a possibility of vehicle vibration based on at least one of the state of the clutch, the vehicle speed, and the state of the transmission. For example, when the clutch is disengaged, there is no possibility that vehicle vibration will occur because the internal combustion engine is disconnected from the drive system. Even when the clutch is connected, if the shift position of the transmission is neutral, there is no risk of vehicle vibration. In addition, there is no risk of vehicle vibration even when the vehicle speed is relatively high. Therefore, it is possible to determine whether or not there is a possibility that vehicle vibration may occur regardless of the clutch state, vehicle speed, or transmission state.

  Further, as in claim 4, even when it is determined that the vehicle vibration determination means may cause vehicle vibration when the brake operation is released during the fuel cut, the driving is performed. The fuel injection may be resumed immediately when the acceleration request of the person is large. In this way, when the driver's acceleration request is large, the acceleration request can be started immediately with priority given to the acceleration request, and the acceleration response can be improved.

  In this case, as in claim 5, the driver's acceleration request may be determined based on the accelerator operation amount detected by the accelerator operation detecting means. In addition, the driver's acceleration request may be determined based on the shift position of the shift lever.

  According to a sixth aspect of the present invention, a starter that rotationally drives the crankshaft of the internal combustion engine when the internal combustion engine is manually started is provided, and the fuel is released when the clutch is disengaged when the fuel injection is resumed from the fuel cut state. It is preferable to determine whether or not the internal combustion engine can be started only by restarting the injection, and when it is determined that it is difficult to start the internal combustion engine only by restarting the fuel injection, the starter is driven to start. In this manner, the starter can be secured while minimizing the frequency of use of the starter at the time of automatic starting and improving the fuel efficiency accordingly.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, the configuration of the entire control system will be described with reference to FIG.
Between the crankshaft of the engine 11 which is an internal combustion engine and the input shaft of the transmission 12, a clutch 13 for connecting / releasing both is provided, and the rotational force of the output shaft of the transmission 12 is controlled by the propeller shaft 14 → the differential gear. 15 → is transmitted to the drive wheel 17 through the path of the drive shaft 16. The transmission 12 is a manual transmission, and the driver performs a shift operation for switching the shift position of the shift lever 18 to switch the gear position of the transmission 12. The transmission 12 is provided with a shift switch 19 that detects the shift position of the shift lever 18.

  The vehicle is provided with a clutch pedal (not shown) for switching connection / release of the clutch 13, the clutch 13 is disconnected by depressing the clutch pedal, and the clutch pedal is released by releasing the depressing operation of the clutch pedal. 13 is connected. The switching of the connection / release of the clutch 13 is detected by the clutch switch 21. The engine 11 is provided with a starter 22, and the engine 11 is started by rotationally driving (cranking) the crankshaft of the engine 11 by the starter 22 at the time of manual start.

  In this embodiment, the engine 11 is an in-cylinder injection engine, for example, which injects fuel into a cylinder that is stopped in the expansion stroke at the start of automatic start and burns it, and cranks the engine 11 with the combustion pressure. By starting, it has a function of performing “starterless start” that starts without using the starter 22. However, at the time of automatic start, if it is determined that it is difficult to start the engine 11 only by restarting fuel injection, the starter 22 is driven to start.

  In addition, an accelerator sensor 23 (accelerator operation detecting means) for detecting an accelerator operation amount (depressing amount of the accelerator pedal), a brake switch 24 (brake operation detecting means) for detecting a brake operation (depressing the brake pedal), a vehicle speed ( A vehicle speed sensor 25 or the like for detecting the wheel speed) is provided.

  Output signals from these various sensors and switches are input to the control device 26. This control device 26 is mainly composed of a microcomputer, and by executing each routine shown in FIGS. 2 to 4 to be described later, the fuel cut is performed during a period in which the brake operation is performed while the accelerator operation is not performed. When the fuel operation is performed and the brake operation is released during the fuel cut, it is determined that there is a possibility that vehicle vibration will occur. The fuel cut is stopped and fuel injection is resumed. However, even if it is determined that there is a risk of vehicle vibration when the brake operation is released during fuel cut, fuel injection is resumed immediately if the driver's acceleration request is large. To do.

  Further, the control device 26 executes a starter control routine of FIG. 5 to be described later, and when the clutch 13 is disengaged when the fuel injection is resumed from the fuel cut state, the engine 11 is simply restarted. It is determined whether or not the engine 11 can be started, and when it is determined that it is difficult to start the engine 11 only by restarting fuel injection, the starter 22 is driven to start. The processing contents of the routines shown in FIGS. 2 to 5 will be described below.

[Fuel cut control routine]
The fuel cut control routine of FIG. 2 is executed at a predetermined cycle during the power-on period of the control device 26, and serves as an automatic stop / start control means in the claims. When this routine is started, first, at step 101, it is determined whether or not the brake is ON (braking operation) based on the output signal of the brake switch 24. Based on the output signal of the sensor 23, it is determined whether or not the accelerator is OFF (a state in which the accelerator operation is not performed). If the accelerator is OFF, the process proceeds to step 103 to perform fuel cut. The state in which the driver performs the brake operation without performing the accelerator operation (accelerator ON) means that the driver does not need the driving force of the engine 11, and therefore, the brake is ON and the accelerator is OFF. For example, a fuel cut will be implemented to reduce fuel consumption. In addition, ignition is cut during fuel cut.

  On the other hand, if it is determined in step 101 that the brake is OFF (the state in which the brake operation is released), the process proceeds to step 104, where it is determined whether or not the engine is idling. The fuel cut is stopped and fuel injection is restarted.

  If it is determined in step 104 that the vehicle is idling, the process proceeds to step 105, where it is determined whether or not there is a possibility of generating vehicle vibration based on the processing result of the vehicle vibration determination routine of FIG. If it is determined that there is a possibility that it will occur, the routine proceeds to step 106 and the fuel cut is continued. If it is determined in step 105 that there is no possibility of causing vehicle vibration, the routine proceeds to step 107, where fuel cut is stopped and fuel injection is restarted.

  If it is determined as “Yes” in step 101 and “No” in step 102, that is, if the accelerator is operated in a brake-on state, the process proceeds to step 109, which will be described later. 3 is determined based on the processing result of the vehicle vibration determination routine in step 3, and if it is determined that there is no possibility of causing vehicle vibration, the process proceeds to step 113, and fuel cut is stopped. Resume fuel injection.

  On the other hand, if it is determined in step 109 that there is a risk of vehicle vibration, the process proceeds to step 110, and the driver's acceleration request is large based on the processing result of the acceleration request determination routine of FIG. If the driver's acceleration request is large, the routine proceeds to step 111, where fuel cut is stopped and fuel injection is restarted. In this case, when the driver's acceleration request is large, even if there is a possibility of causing vehicle vibration, the driver's acceleration request is prioritized and acceleration can be started immediately.

  If it is determined that there is a risk of vehicle vibration, if it is determined in step 110 that the driver's acceleration request is not large, the process proceeds to step 112 and fuel cut is continued. This prevents the occurrence of vehicle vibration.

[Vehicle vibration determination routine]
The vehicle vibration determination routine of FIG. 3 is executed at a predetermined cycle during the power-on period of the control device 26, and serves as vehicle vibration determination means in the claims. When this routine is started, first, at step 201, it is determined whether or not the clutch 13 is disengaged based on the output signal of the clutch switch 21, and if the clutch 13 is disengaged, the engine 11 is disconnected from the drive system. Therefore, the process proceeds to step 204 and it is determined that there is no possibility of causing vehicle vibration.

  On the other hand, if it is determined in step 201 that the clutch 13 is not disengaged, the routine proceeds to step 202, where whether or not the shift position of the shift lever 18 is neutral based on the output signal of the shift switch 19 is determined. If it is neutral, the power of the engine 11 is not transmitted to the drive system (substantially the same state as when the clutch 13 is disengaged). It is determined that there is no risk of it occurring.

  If it is determined in step 202 that the vehicle is not neutral, the process proceeds to step 203, where it is determined whether the vehicle speed is equal to or higher than a determination value based on the output signal of the vehicle speed sensor 25. Here, a predetermined value may be used as the determination value, but whether or not the determination value is changed by a map or the like according to the gear position of the transmission 12 may cause vehicle vibration. Can be determined with higher accuracy. For example, since the rotational speed of the engine 11 (the rotational speed on the input shaft side of the transmission 12) becomes higher and the vehicle vibration is less likely to occur in the lower gear even at the same vehicle speed, the determination value may be made smaller in the lower gear. .

  If it is determined in step 203 that the vehicle speed is greater than or equal to the determination value, the process proceeds to step 204, where it is determined that there is no possibility of causing vehicle vibration. If the vehicle speed is determined to be less than the determination value, the process proceeds to step 205, where It is determined that there is a risk of occurrence.

[Acceleration request judgment routine]
The acceleration request determination routine of FIG. 4 is executed at a predetermined cycle during the power-on period of the control device 26. When this routine is started, first, at step 301, it is determined whether or not the accelerator operation amount (depressed amount of the accelerator pedal) detected by the accelerator sensor 23 is greater than or equal to a predetermined value, and the accelerator operation amount is greater than or equal to the predetermined value. If there is, the routine proceeds to step 302, where it is determined that the driver's acceleration request is large. If the accelerator operation amount is less than the predetermined value, the routine proceeds to step 303, where it is determined that the driver's acceleration request is not large.

[Starter control routine]
The starter control routine of FIG. 5 is executed in a predetermined cycle during the power-on period of the control device 26, and serves as an automatic stop / start control means in the claims. When this routine is started, first, at step 401, it is determined whether or not it is "manual start" when the driver operates the ignition switch (not shown) to start the engine 11, and at the time of manual start. If there is, the routine proceeds to step 405, where the starter 22 is driven and the crankshaft of the engine 11 is rotationally driven (cranking) to start the engine 11.

  On the other hand, if it is determined in step 401 that it is not at the time of manual start, the routine proceeds to step 402, where it is “automatic start” at which the fuel injection is resumed from the fuel cut state and the engine 11 is started. If it is not at the time of automatic start, this routine is terminated as it is.

  If it is determined in step 402 that the automatic start is in progress, the process proceeds to step 403, where it is determined whether or not the clutch 13 is disengaged. If the clutch 13 is not disengaged, this routine is terminated as it is. If it is cut off, the routine proceeds to step 404, where it is determined whether or not it is difficult to start the engine 11 in the starterless start only by fuel injection. For example, if the engine stop position (engine start start position) is not within a predetermined crank angle range suitable for starterless start, it is determined that it is difficult to start only with fuel injection. Further, if the coolant temperature is equal to or lower than the predetermined temperature, it is determined that the friction of the engine 11 during cranking is large and it is difficult to start only by fuel injection.

  If it is determined in step 404 that it is difficult to start only with fuel injection, the process proceeds to step 405 where the starter 22 is driven to rotate (crank) the crankshaft of the engine 11 to start the engine 11. If it is determined in step 404 above that the engine can be started only by fuel injection (starterless start is possible), this routine is terminated. In this case, starterless start with only fuel injection is executed.

  In general, a state in which the driver performs the brake operation without performing the accelerator operation means that the driver does not need the driving force of the engine 11. In normal fuel cut control during deceleration, when the engine speed drops below the fuel cut return rotation speed during deceleration, recovery from fuel cut during deceleration resumes and fuel injection resumes. In some cases, the brake operation is performed without performing the accelerator operation (that is, the driving force of the engine 11 is not required). Also in such a case, when the fuel injection is resumed after returning from the fuel cut, the combustion torque of the engine 11 is consumed by the brake operation, and the fuel is consumed wastefully.

  Therefore, in this embodiment, the fuel cut is executed during the brake ON period in which the brake operation is performed in the accelerator OFF state where the accelerator operation is not performed. Even when the driving speed of the engine 11 is not required even in the region of the rotational speed or less, it becomes possible to execute the fuel cut, and to improve the fuel consumption.

  In addition, when the brake operation is released during the fuel cut, the fuel cut is continued during the period when it is determined that there is a possibility that the vehicle vibration may occur. Since the fuel injection is resumed after returning from the fuel cut, it is possible to prevent the vehicle vibration from occurring when the fuel cut is restored.

  Furthermore, even if it is determined that there is a possibility that vehicle vibration may occur when the brake operation is released during fuel cut, fuel injection is resumed immediately if the driver's acceleration request is large Thus, when the driver's acceleration request is large, the acceleration request can be started immediately with priority given to the acceleration request, and the acceleration response can be improved.

  Further, when the clutch 13 is disengaged when the fuel injection is resumed from the fuel cut state, it is determined whether or not the engine 11 can be started only by resuming the fuel injection. When the starter 22 is determined to be difficult to start, the starter 22 is driven to start, so the frequency of use of the starter 22 at the time of automatic start is minimized, and the startability is improved while improving the fuel consumption. It can be secured.

  The present invention is also applicable to a vehicle equipped with an intake port injection engine. When starterless start is performed with an intake port injection engine, fuel is injected into a cylinder that stops in the expansion stroke when the engine is automatically stopped, and an air-fuel mixture is confined in the expansion stroke cylinder. ) To ignite the air-fuel mixture in the expansion stroke cylinder. Of course, in the present invention, the starterless start may not be performed at the time of automatic start, and the starter 22 may always be driven to automatically start.

  In addition, the present invention omits the function of determining whether or not there is a possibility of vehicle vibration, and is there a possibility that vehicle vibration may occur when the brake operation is released during the fuel cut? It is possible to implement various modifications within a range that does not depart from the gist, for example, it is possible to immediately return from the fuel cut and restart the fuel injection without determining whether or not.

It is a figure which shows the structure of the whole control system in one Example of this invention. It is a flowchart which shows the flow of a process of a fuel cut control routine. It is a flowchart which shows the flow of a process of a vehicle vibration determination routine. It is a flowchart which shows the flow of a process of an acceleration request determination routine. It is a flowchart which shows the flow of a process of a starter control routine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Transmission, 13 ... Clutch, 18 ... Shift lever, 19 ... Shift switch, 21 ... Clutch switch, 22 ... Starter, 23 ... Accelerator sensor (accelerator operation detection means), 24 ... Brake Switch (brake operation detection means), 25 ... vehicle speed sensor, 26 ... control device (automatic stop / start control means, vehicle vibration determination means)

Claims (6)

A clutch for connecting / releasing a path for transmitting the power of the internal combustion engine to the drive system, and automatic stop start control means for cutting fuel under a predetermined automatic stop condition and restarting fuel injection from the fuel cut state under a predetermined automatic start condition In a control device for an internal combustion engine applied to a vehicle comprising:
An accelerator operation detecting means for detecting an accelerator operation;
Brake operation detecting means for detecting the brake operation,
The control apparatus for an internal combustion engine, wherein the automatic stop / start control means performs a fuel cut during a period in which a brake operation is performed in a state where an accelerator operation is not performed. Vehicle vibration determination means for determining whether or not vehicle vibration may occur,
The automatic stop / start control means continues the fuel cut during a period when the vehicle vibration determination means determines that vehicle vibration may occur when a brake operation is released during the fuel cut. 2. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel injection is resumed when there is no longer a possibility of occurrence of vehicle vibration.   The vehicle vibration determination means determines whether or not vehicle vibration is likely to occur based on at least one of the state of the clutch, the vehicle speed, and the state of the transmission. Control device for internal combustion engine.   The automatic stop / start control means operates even when it is determined that the vehicle vibration determination means may cause vehicle vibration when a brake operation is released during the fuel cut. 4. The control device for an internal combustion engine according to claim 2, wherein the fuel injection is restarted immediately when the acceleration request of the user is large.   5. The control apparatus for an internal combustion engine according to claim 4, wherein the automatic stop / start control means includes means for determining the acceleration request of the driver based on an accelerator operation amount detected by the accelerator operation detection means. . A starter that rotationally drives the crankshaft of the internal combustion engine when the internal combustion engine is manually started;
If the clutch is disengaged when the fuel injection is restarted from the fuel cut state, the automatic stop start control means determines whether or not the internal combustion engine can be started only by restarting the fuel injection. 6. The control apparatus for an internal combustion engine according to claim 1, wherein when the internal combustion engine is determined to be difficult to start only by restarting the injection, the starter is driven to start.

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