JP5578113B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly, to a control device for an internal combustion engine that includes a supercharger and that automatically stops when a predetermined idle stop condition is satisfied and then restarts. .

  Conventionally, for the purpose of improving fuel consumption and reducing carbon dioxide emission, a so-called idle stop is known in which an engine is temporarily stopped and then restarted while waiting for a vehicle signal or during a traffic jam stop. Moreover, what applied such an idle stop to the internal combustion engine provided with a supercharger is also known.

  For example, Patent Document 1 discloses that in an internal combustion engine including a supercharger, idle stop is temporarily prohibited when the temperature of the supercharger is equal to or higher than a predetermined value. Further, for example, Patent Document 2 discloses that in an internal combustion engine including a supercharger with a motor, the motor is operated prior to restarting the engine after the idling stop. In an internal combustion engine equipped with a supercharger as in Patent Document 1 described above, a response delay in supercharging pressure (hereinafter referred to as “turbo lag”) occurs when the engine is restarted after an idle stop when the driver depresses the accelerator. In addition, there is a problem such as worsening of the drivability associated therewith. In this regard, according to the control device of Patent Document 2, since the electric motor is operated prior to engine restart, the turbo rotation speed can be increased in advance. Therefore, generation | occurrence | production of a turbo lag and deterioration of drivability can be prevented.

Japanese Patent Laid-Open No. 09-042003 JP 2008-095669 A JP 2002-276411 A JP 2010-084516 A JP 2006-046250 A JP 2010-084660 A JP 2004-225561 A

  However, in Patent Document 2, since a battery is used for the operation of the electric motor, the amount of power used by the battery increases, which may lead to deterioration in fuel consumption. If the battery is used before the engine is restarted, sufficient power cannot be supplied to the starter motor used at the time of starting the engine, and the engine startability may be reduced. Therefore, it has been necessary to make an improvement capable of preventing the occurrence of turbo lag without causing such a problem.

  The present invention has been made to solve the above-described problems. That is, an object of the present invention is to provide a control device for an internal combustion engine that can prevent the occurrence of a turbo lag even in an internal combustion engine equipped with a supercharger without a motor.

In order to achieve the above object, a first invention is a control device for an internal combustion engine having a plurality of cylinders,
A supercharger that operates by exhaust energy and supercharges intake air to the plurality of cylinders;
Whether the predetermined condition regarding the amount of fresh air sucked into the plurality of cylinders when the turbocharger is restarted is assumed when the turbocharger is temporarily stopped and then restarted Predetermined condition determining means for determining whether or not ,
Idle stop means for stopping all of the plurality of cylinders when the predetermined condition is satisfied, and stopping a part of the plurality of cylinders when the predetermined condition is not satisfied;
It is characterized by providing.

According to a second invention, in the first invention,
An outside temperature acquisition means for acquiring outside temperature is provided,
The predetermined condition determining means determines whether or not the predetermined condition is satisfied based on whether or not the outside air temperature is lower than a set temperature.

According to a third invention, in the first invention,
An external air pressure acquisition means for acquiring the external air pressure is provided,
The predetermined condition determining means determines whether or not the predetermined condition is satisfied based on whether or not the external air pressure is higher than a set pressure.

According to a fourth invention, in the first invention,
Outside temperature acquisition means for acquiring outside temperature;
An external air pressure acquisition means for acquiring the external air pressure,
The predetermined condition determining means determines whether or not the predetermined condition is satisfied based on whether or not the outside air temperature is lower than a set temperature and the outside air pressure is higher than a set pressure.

  According to the first aspect, the predetermined condition determination means can determine whether or not the predetermined condition regarding the amount of fresh air taken into the plurality of cylinders when the turbocharger is reactivated. When the turbocharger is restarted, if the amount of fresh air sucked into the plurality of cylinders is small, the rotation becomes insufficient, and therefore, the turbo lag is likely to be generated. Therefore, if the success or failure of the predetermined condition can be determined, it is possible to stop all cylinders when the fresh air amount is sufficient, and to stop only some cylinders when the fresh air amount is small. . Therefore, according to the present invention, it is possible to improve fuel efficiency by stopping the cylinder while preventing the occurrence of turbo lag without using an electric motor.

  According to the second to fourth inventions, the predetermined condition can be set by the outside air temperature, the outside air pressure, or a combination thereof. According to the outside air temperature, the outside air pressure, or a combination thereof, when it is assumed that the turbocharger is temporarily stopped and then restarted, it is sucked into a plurality of cylinders when the turbocharger is restarted. The amount of fresh air that can be estimated. Also, the outside air temperature and the outside air pressure can be easily obtained with a simple configuration. Therefore, according to these inventions, generation of turbo lag can be prevented with a simple configuration.

It is a figure for demonstrating the system configuration | structure of embodiment. 4 is a flowchart showing turbo rotation speed control executed by an ECU 50 in the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram for explaining a system configuration according to an embodiment of the present invention. The system according to the present embodiment includes an engine 10 as an internal combustion engine mounted on a vehicle. Note that the number of cylinders and the cylinder arrangement of the engine 10 are not particularly limited.

  Each cylinder of the engine 10 is provided with an injector 12 that injects fuel directly into the cylinder. The injector 12 is connected to a common rail 14 common to them. In the common rail 14, fuel pressurized by the supply pump 16 is stored. Then, pressurized fuel is supplied from the common rail 14 to each injector 12.

  As shown in FIG. 1, an exhaust passage 18 is connected to the engine 10 via an exhaust manifold 20. In the middle of the exhaust passage 18, a turbine 22a of the turbocharger 22 is disposed. Similarly, an intake passage 24 is connected to the engine 10 via an intake manifold 26. In the middle of the intake passage 24, a compressor 22b of the turbocharger 22 and an intercooler 28 are arranged. An air cleaner 30 is provided near the inlet of the intake passage 24. The air sucked through the air cleaner 30 is compressed by the compressor 22 b of the turbocharger 22, cooled by the intercooler 28, and sucked into each cylinder through the intake manifold 26.

  An electronically controlled throttle valve 32 is installed in the intake passage 24 between the intercooler 28 and the intake manifold 26. A throttle position sensor (not shown) for detecting the opening degree of the throttle valve 32 is provided in the vicinity of the throttle valve 32.

  Further, the system of the present embodiment includes an ECU (Electronic Control Unit) 50 as a control device. An injector 12 and the like are connected to the output side of the ECU 50. On the other hand, a temperature sensor 34 for detecting the outside air temperature, a pressure sensor 36 for detecting the outside air pressure, and the like are connected to the input side of the ECU 50. The installation location of the temperature sensor 34 and the pressure sensor 36 is not particularly limited, and a sensor capable of detecting the outside air temperature and the outside air pressure, such as an existing cooling water temperature sensor and an intake pipe pressure sensor, instead of the temperature sensor 34 and the pressure sensor 36. It is also possible to use. The ECU 50 can control various actuators such as the injector 12 based on these sensor signals.

[Features of the embodiment]
One of the controls of the engine 10 by the ECU 50 is start and stop control (hereinafter referred to as “S & S control”). The S & S control is a control in which the engine 10 is temporarily stopped at the time of idling for the purpose of improving fuel consumption and then restarted. However, in the S & S control, if the engine 10 is temporarily stopped, the rotation of the turbine 22a is also stopped. Therefore, at the time of restart, the rotation of the turbine 22a starts from the state where the rotational speed is zero. Therefore, even if the throttle valve 32 is opened when the engine 10 is restarted, the amount of fresh air sucked into the cylinder does not differ from the amount of fresh air when the NA engine is started. Therefore, turbo lag is generated from the NA torque until the boost pressure rises.

  In particular, due to the increasing demand for fuel efficiency in recent years, a small supercharged engine has been developed that aims to improve fuel efficiency by reducing the engine displacement while ensuring the same output as a large displacement engine. Such a small supercharged engine has a small displacement and therefore has a small NA torque. Therefore, when such a small supercharged engine is applied to the engine 10 of the present embodiment, the rise of the supercharging pressure tends to be delayed, and the probability of occurrence of turbo lag becomes extremely high. Therefore, in the present embodiment, the S & S control described above and the cylinder stop control for stopping a part of the cylinders of the engine 10 according to the conditions (temperature and pressure) of the outside air in order to maintain a constant turbo speed. (Turbo rotational speed control).

  Specifically, the turbo rotation speed control in the present embodiment executes the S & S control when the outside air temperature is lower than the normal temperature (25 ° C.) or when the outside air pressure is high, and executes the cylinder stop control otherwise. Is. When the outside air temperature is lower than the normal temperature, the volume of fresh air is reduced, so that the amount of fresh air sucked into the cylinder when the throttle valve 32 is opened increases. Further, when the outside air pressure is high, the differential pressure between the intake pipe pressure and the in-cylinder pressure increases, so that the amount of fresh air sucked into the cylinder by the negative pressure increases.

  On the other hand, when the outside air temperature is equal to or higher than room temperature or when the outside air pressure is low, the amount of fresh air sucked into the cylinder is relatively reduced. Therefore, according to the turbo rotational speed control, it is possible to compensate for fluctuations in the amount of fresh air sucked into the cylinder, and therefore it is possible to prevent the occurrence of turbo lag by speeding up the rise of the supercharging pressure when the vehicle restarts. In particular, if cylinder stop control is executed, fuel supply to some cylinders is cut off, so that fuel efficiency can be improved compared to idling. Therefore, it is possible to achieve both prevention of turbo lag and improvement of fuel consumption.

[Specific processing in this embodiment]
Next, with reference to FIG. 2, a specific process for realizing the above-described turbo rotation speed control will be described. FIG. 2 is a flowchart showing turbo rotational speed control executed by the ECU 50 in the present embodiment.

  In the routine shown in FIG. 2, first, the ECU 50 determines whether or not an idle stop condition is satisfied (step 100). In this step, the idle stop condition is, for example, a state in which the accelerator pedal is not depressed, the battery storage amount is more than a necessary amount, and the vehicle speed zero state continues for a set time or more, and Set when the brake pedal is depressed. If it is determined that all of the idle stop conditions are not satisfied, the ECU 50 ends this routine and returns to normal engine control.

  On the other hand, when it is determined that the idle stop condition is satisfied, the ECU 50 determines whether or not the outside air temperature is low (step 110). In this step, specifically, the ECU 50 determines whether or not the detection value of the temperature sensor 34 is lower than the determination value of the outside air temperature. In the present embodiment, the determination value of the outside air temperature is room temperature, and a value stored in advance in the ECU 50 is used. The ECU 50 proceeds to step 120 when it is determined that the detection value of the temperature sensor 34 is lower than the normal temperature, and proceeds to step 130 when it is determined that it is not.

  In step 120, the ECU 50 determines whether or not the external atmospheric pressure is not low. In this step, specifically, the ECU 50 determines whether or not the detection value of the pressure sensor 36 is higher than the determination value of the external atmospheric pressure. In the present embodiment, the determination value of the external air pressure is set in advance through experiments, simulations, or the like, and a value stored in advance in the ECU 50 is used. The ECU 50 proceeds to step 140 when it is determined that the detection value of the pressure sensor 36 is higher than the determination value, and proceeds to step 130 when it is determined that it is not.

  In step 130, the ECU 50 performs cylinder stop control for stopping some cylinders of the engine 10. Specifically, the ECU 50 controls the injector 12 to shut off fuel supply to one cylinder of the engine 10. On the other hand, in step 140, the ECU 50 stops all the cylinders of the engine 10 and executes S & S control for restarting these cylinders when at least one of the idle stop conditions is not satisfied.

  As described above, according to the routine shown in FIG. 2, when the detected value of the temperature sensor 34 is determined to be equal to or higher than the normal temperature, or when the detected value of the pressure sensor 36 is determined to be equal to or lower than the determined value of the external air pressure, The cylinder stop control for stopping a part of the cylinders can be executed. Accordingly, it is possible to prevent the turbo lag from occurring by increasing the rise of the supercharging pressure when the vehicle restarts, and to prevent the deterioration of the drivability associated with the turbo lag.

  In the above-described embodiment, the S & S control and the cylinder stop control are switched using the determination conditions of steps 110 and 120 in the routine shown in FIG. These controls may be switched using conditions. Further, if it is assumed that all cylinders of the engine 10 are stopped by S & S control and then restarted, these conditions can be used as long as the amount of fresh air sucked into the cylinder after the restart can be determined. It can be applied as another condition for switching the control.

In the present embodiment described above, the ECU 50 executes the processing of steps 110 and 120 in FIG. 2 so that the “predetermined condition determining means” in the first invention performs the processing of steps 130 and 140 in FIG. By executing, the “idle stop means” in the first aspect of the present invention is realized.
In the present embodiment described above, the temperature sensor 34 corresponds to the “outside air temperature acquisition means” in the second and fourth inventions.
In the present embodiment described above, the pressure sensor 36 corresponds to the “outside air pressure acquisition means” in the third and fourth inventions.

DESCRIPTION OF SYMBOLS 10 Engine 12 Injector 14 Common rail 16 Supply pump 18 Exhaust passage 20 Exhaust manifold 20 Turbocharger 22a Turbine 22b Compressor 24 Intake passage 26 Intake manifold 28 Intercooler 30 Air cleaner 32 Throttle valve 34 Temperature sensor 36 Pressure sensor 50 ECU

Claims (4)

A control device for an internal combustion engine having a plurality of cylinders,
A supercharger that operates by exhaust energy and supercharges intake air to the plurality of cylinders;
Whether the predetermined condition regarding the amount of fresh air sucked into the plurality of cylinders when the turbocharger is restarted is assumed when the turbocharger is temporarily stopped and then restarted Predetermined condition determining means for determining whether or not ,
Idle stop means for stopping all of the plurality of cylinders when the predetermined condition is satisfied, and stopping a part of the plurality of cylinders when the predetermined condition is not satisfied;
A control device for an internal combustion engine, comprising: An outside temperature acquisition means for acquiring outside temperature is provided,
2. The control device for an internal combustion engine according to claim 1, wherein the predetermined condition determination unit determines whether or not the predetermined condition is satisfied based on whether or not the outside air temperature is lower than a set temperature. An external air pressure acquisition means for acquiring the external air pressure is provided,
2. The control device for an internal combustion engine according to claim 1, wherein the predetermined condition determination unit determines whether or not the predetermined condition is satisfied based on whether or not the external air pressure is higher than a set pressure. Outside temperature acquisition means for acquiring outside temperature;
An external air pressure acquisition means for acquiring the external air pressure,
The said predetermined condition determination means determines the success or failure of the said predetermined condition by whether the said external temperature is lower than preset temperature and the said external pressure is higher than preset pressure. Control device for internal combustion engine.

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