JP2010116896A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a control device for an internal combustion engine, capable of increasing the negative pressure of intake air in operation to permit the effect of engine brake to be improved even in an internal combustion engine equipped with an electrically-operated supercharger. <P>SOLUTION: The control device includes an electrically-operated supercharger 5 which is provided in a vehicle-mounted internal combustion engine 1 and supercharges the intake air sucked into a cylinder through an intake-air passage 3 by driving and rotating a compressor wheel 8 by means of an electric motor 9 and is capable of decreasing the pressure of the intake air by accelerating the electric motor 9 in the reverse direction to the direction of supercharging the intake air; an operational status detecting means for detecting the operational status of a vehicle; and an electric motor control device 19 for calculating a target supercharging pressure being a target value of the pressure of intake air, based on the operational status to control the electric motor 9 depending on the target supercharging pressure. When the operational status is in an acceleration unneeded status where the vehicle needs not be accelerated, the electric motor control device 19 halts the control of the electric motor 9, determined depending on the target supercharging pressure and then accelerates the electric motor 9 in the reverse direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that controls an electric supercharger in accordance with a driving state of a vehicle.

  Generally, in order to increase the output of an internal combustion engine, it is known to increase the pressure of intake air (intake pressure) sucked into a cylinder using an electric supercharger (supercharge the intake air in the cylinder). It has been. In recent years, in addition to the purpose of increasing the output, it is known to provide an electric supercharger in the internal combustion engine in order to reduce the displacement of the internal combustion engine and reduce fuel consumption.

For example, a conventional control device for an internal combustion engine is equipped with an electric supercharger that supercharges the inside of a cylinder using the exhaust energy of the internal combustion engine and the rotation of the rotating shaft is assisted by the electric motor, and the accelerator opening degree and the internal combustion engine The assist force by the electric motor is controlled based on the target rotational speed of the electric supercharger determined based on the rotational speed of the motor (see, for example, Patent Document 1).
According to the control device of Patent Document 1, it is possible to perform control according to the driving state of the vehicle by taking advantage of the good controllability of the electric motor.

Further, the conventional control device for an internal combustion engine includes an electric supercharger capable of reducing the intake pressure by operating the electric motor in a direction opposite to the direction in which the intake air in the cylinder is supercharged. The ignition of the air-fuel mixture in the cylinder is started after the motor is operated in the reverse direction to reduce the intake pressure (see, for example, Patent Document 2).
According to the control device of Patent Literature 2, it is possible to reduce vibration and sound at the time of starting by reducing the air filling efficiency in the cylinder.

Japanese Laid-Open Patent Publication No. 2007-77909 JP 2007-92679 A

However, the prior art has the following problems.
In the control device for a conventional internal combustion engine described in the cited document 1, the intake negative pressure is reduced by supercharging the intake air in the cylinder. Here, the relationship between the accelerator opening and the intake negative pressure is illustrated in FIG. 5 for an internal combustion engine equipped with an electric supercharger and an internal combustion engine not equipped with an electric supercharger. From FIG. 5, it can be seen that the intake negative pressure is reduced particularly in the region where the accelerator opening is low in the internal combustion engine provided with the electric supercharger. When intake negative pressure is reduced, cylinder pumping loss is reduced, and engine braking is not effective.

  Further, in the control device for a conventional internal combustion engine described in the cited document 2, the intake air pressure is reduced and the intake negative pressure is increased by operating the motor in a direction opposite to the direction in which the intake air in the cylinder is supercharged. However, this is a process only when the internal combustion engine is started. Therefore, during the operation of the internal combustion engine, that is, while the vehicle is running, there is a problem that the intake negative pressure is reduced in the same manner as in the cited reference 1 and the effectiveness of the engine brake is deteriorated.

  The present invention has been made to solve the above-described problems, and its object is to increase intake negative pressure during operation even in an internal combustion engine equipped with an electric supercharger. It is possible to obtain a control device for an internal combustion engine capable of increasing the pumping loss and improving the effectiveness of engine braking.

  A control device for an internal combustion engine according to the present invention is provided in an internal combustion engine mounted on a vehicle, and supercharges intake air sucked into a cylinder through an intake passage when an electric motor rotates a compressor wheel. , By accelerating the motor in the direction opposite to the direction of supercharging the intake air, the electric supercharger capable of reducing the intake pressure, the driving state detecting means for detecting the driving state of the vehicle, and the suction based on the driving state A control unit that calculates a target supercharging pressure that is a target value of the atmospheric pressure and controls the electric motor according to the target supercharging pressure, and the control unit is in an acceleration-unnecessary state that does not require acceleration of the vehicle In addition, the control of the electric motor according to the target supercharging pressure is stopped, and the electric motor is accelerated in the reverse direction.

According to the control device for an internal combustion engine of the present invention, the control means responds to the target boost pressure when the driving state of the vehicle detected by the driving state detection means is an acceleration unnecessary state that does not require acceleration of the vehicle. The control of the electric motor is stopped, and the electric motor of the electric supercharger is accelerated in the direction opposite to the direction of supercharging the intake air to reduce the intake pressure.
Therefore, even in an internal combustion engine equipped with an electric supercharger, the intake negative pressure can be increased during operation, and the pumping loss can be increased to improve the engine braking effectiveness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be described with the same reference numerals.

Embodiment 1 FIG.
1 is a configuration diagram showing an entire system including a control device for an internal combustion engine according to Embodiment 1 of the present invention. The internal combustion engine 1 shown in FIG. 1 is a four-cylinder gasoline engine, and achieves high output and low fuel consumption by supercharging intake air in the cylinder using an electric supercharger 5. .

  Note that there is no limit on the number of cylinders in the applied engine. Further, the combustion method of the engine is not limited, and may be applied to a direct injection engine that directly injects fuel into a cylinder, or a port injection engine that injects fuel into an intake manifold 14 on the downstream side of the throttle valve 11. May be applied.

In FIG. 1, an intake passage 3 and an exhaust passage 4 are connected to a cylinder portion 2 of the internal combustion engine 1. An electric supercharger 5 is provided between the intake passage 3 and the exhaust passage 4.
The electric supercharger 5 is connected coaxially via a turbine wheel 6 that is rotated by exhaust gas generated in each cylinder of the cylinder portion 2, and the turbine wheel 6 and a rotation shaft 7. It has a compressor wheel 8 that compresses and an electric motor 9 that rotationally drives the rotary shaft 7.

  Further, the electric supercharger 5 supercharges the intake gas sucked into the cylinder through the intake passage 3 by the exhaust gas generated in the cylinder portion 2 or the rotational drive of the electric motor 9 and also supercharges the intake air. By accelerating the electric motor 9 in the opposite direction, the intake pressure can be reduced and the intake negative pressure can be increased. The electric supercharger 5 supercharges intake air by rotating the electric motor 9 when the internal combustion engine 1 rotates at low speed, and supercharges intake air by exhaust gas when the internal combustion engine 1 rotates at high speed.

  An intercooler 10 that cools the intake air is provided downstream of the electric supercharger 5 in the intake passage 3. A throttle valve 11 that adjusts the flow rate of intake air flowing through the intake passage 3 is provided on the downstream side of the intercooler 10. A throttle actuator 12 that opens and closes the throttle valve 11 is attached to the throttle valve 11.

An intake pressure sensor 13 (intake pressure detection means) that detects the intake pressure downstream of the electric supercharger 5 is provided on the downstream side of the throttle valve 11.
Further, the downstream side of the intake passage 3 with respect to the throttle valve 11 branches according to each cylinder of the cylinder portion 2 to form an intake manifold 14. Further, the upstream side of the exhaust passage 4 is branched according to each cylinder of the cylinder portion 2 to form an exhaust manifold 15.

Here, the flow until the intake air taken into the intake passage 3 of the internal combustion engine 1 is discharged from the exhaust passage 4 will be described.
First, dust is removed from the intake air taken into the intake passage 3 from the atmosphere by an air cleaner (not shown). Subsequently, the intake air from which the dust has been removed is compressed by the rotation of the compressor wheel 8 of the electric supercharger 5.

  Next, since the temperature of the compressed intake air rises due to an increase in pressure and is about to expand, the compressed intake air is cooled by the intercooler 10 in order to improve the charging efficiency. Subsequently, the flow rate of the cooled intake air is adjusted according to the opening degree of the throttle valve 11 driven by the throttle actuator 12, and in the case of a port injection engine, fuel is mixed so that each cylinder in the cylinder portion 2 is mixed. Inhaled.

  Next, the air-fuel mixture sucked into the cylinder is ignited, and a piston (not shown) in the cylinder is pushed down. Subsequently, the vertical motion of the piston is converted into a rotational motion by a crank (not shown), which is used as motive power as a driving force of the vehicle.

  Further, exhaust gas generated by the combustion in the cylinder is discharged through the exhaust manifold 15. Subsequently, the exhaust gas discharged from the cylinder passes through the turbine wheel 6 of the electric supercharger 5 and rotates the turbine wheel 6. The exhaust gas that has rotated the turbine wheel 6 is purified by a muffler (not shown) integrated with an exhaust gas purification catalyst and the like, and is discharged from the exhaust passage 4 into the atmosphere.

Further, the internal combustion engine 1 is provided with a booster 17 that assists the braking force generated by stepping on the brake pedal 16, and a pipe 18 that introduces intake air to the booster 17 is connected to the intake manifold 14. Has been. The brake pedal 16 outputs the amount of brake depression to the engine control device 20 (described later).
Here, the booster 17 is a known device that assists the braking force by using the intake negative pressure of the intake passage 3, and detailed description thereof is omitted.

  Further, an electric motor control device 19 (control means, accelerator operation detection means) is connected to the electric motor 9 of the electric supercharger 5, and an intake pressure sensor 13 and an engine control device 20 are connected to the electric motor control device 19. ing. The electric motor control device 19 and the engine control device 20 are arithmetic and logic operation capable circuits including a CPU, a RAM, a ROM, and the like.

  The engine control device 20 includes a throttle actuator 12, a brake pedal 16, an acceleration sensor 21 (acceleration detection means), a vehicle speed sensor 22 (vehicle speed detection means), a gradient sensor 23 (gradient angle detection means), and an accelerator pedal 24 (accelerator). Operation detecting means) is connected.

  The acceleration sensor 21 detects the acceleration of the vehicle and outputs it to the engine control device 20. The vehicle speed sensor 22 detects the vehicle speed of the vehicle and outputs it to the engine control device 20. The gradient sensor 23 detects a gradient angle with respect to the traveling direction of the vehicle and outputs it to the engine control device 20. The accelerator pedal 24 outputs the accelerator opening to the engine control device 20.

  The engine control device 20 receives the brake depression amount from the brake pedal 16, the acceleration from the acceleration sensor 21, the vehicle speed from the vehicle speed sensor 22, the gradient angle from the gradient sensor 23, and the accelerator opening from the accelerator pedal 24. Then, the engine control device 20 outputs a command for controlling the opening degree of the throttle valve 11 to the throttle actuator 12 and outputs the acceleration, the vehicle speed, the gradient angle, and the accelerator opening degree to the electric motor control device 19 as operating states.

The electric motor control device 19 calculates a necessary supercharging pressure (target supercharging pressure) based on the operating state from the engine control device 20 and feeds back the electric motor 9 in comparison with the intake pressure detected by the intake pressure sensor 13. Control.
Specifically, when the detected intake pressure is lower than the calculated required supercharging pressure, the motor control device 19 increases the intake pressure by rotating the motor 9 in the supercharging direction. When the calculated intake pressure is higher than the calculated required supercharging pressure, the intake pressure is reduced by accelerating the electric motor 9 in the direction opposite to the supercharging direction. In addition, when the compressor wheel 8 can obtain sufficient rotation speed by exhaust gas, you may regenerate the electric motor 9 as a generator.

In addition, when the operation state from the engine control device 20 is an acceleration unnecessary state that does not require acceleration of the vehicle, the electric motor control device 19 stops the control of the electric motor 9 according to the required supercharging pressure, and the electric motor 9 Is accelerated in the direction opposite to the supercharging direction to reduce the intake pressure. Further, when the operation state from the engine control device 20 is an acceleration unnecessary state, the electric motor control device 19 calculates a required brake negative pressure (target negative pressure) that is a required intake negative pressure based on the operation state, The motor 9 may be feedback controlled as compared with the intake pressure detected by the intake pressure sensor 13.
The electric motor control device 19 may perform feedforward control of the electric motor 9 based on the necessary supercharging pressure or the necessary brake negative pressure.

  Here, the acceleration unnecessary state means that the accelerator pedal 24 is depressed when the vehicle acceleration is a negative value, when the vehicle speed is higher than a predetermined speed, or when the vehicle gradient angle is an angle indicating a downward gradient. This is not the case. In addition, you may determine with an acceleration unnecessary state when one of these conditions is satisfy | filled, and you may determine with an acceleration unnecessary state when several conditions are satisfy | filled simultaneously.

Next, an example of the operation of the electric motor control device 19 according to Embodiment 1 of the present invention will be described with reference to the flowchart of FIG.
First, the electric motor control device 19 receives the accelerator opening from the engine control device 20, and determines whether or not the accelerator pedal 24 is depressed (step S1).

  If it is determined in step S1 that the accelerator pedal 24 is not depressed (that is, No), the electric motor control device 19 determines that there is a possibility of using the brake, and secures the necessary brake negative pressure. Therefore, the process proceeds to step S2.

  Subsequently, the electric motor control device 19 receives the driving state (acceleration, vehicle speed, and gradient angle) from the engine control device 20 (step S2), and calculates the necessary brake negative pressure based on the driving state (step S3). Here, FIG. 3 shows an example of an operating state that is a reference for calculating the required brake negative pressure. As can be seen from FIG. 3, when the acceleration during deceleration is large, when the vehicle speed is large, and when the gradient angle is a downward gradient, the required brake negative pressure increases.

Next, the electric motor control device 19 determines whether or not the intake pressure detected by the intake pressure sensor 13 is smaller than the required brake negative pressure (step S4).
If it is determined in step S4 that the intake pressure is smaller than the brake-required negative pressure (ie, Yes), the processing in FIG.

On the other hand, if it is determined in step S4 that the intake pressure is equal to or higher than the brake-necessary negative pressure (that is, No), the motor control device 19 accelerates the motor 9 in the direction opposite to the supercharging direction to perform suction. The atmospheric pressure is reduced (step S5), and the process of FIG.
At this time, by driving the electric motor 9 in accordance with the differential pressure between the required brake negative pressure and the intake pressure, the optimum required brake negative pressure can be ensured.

  On the other hand, when it is determined in step S1 that the accelerator pedal 24 is depressed (that is, Yes), the electric motor control device 19 determines that the output of the internal combustion engine 1 needs to be improved, and takes the intake air. The process proceeds to step S6 for supercharging.

  Subsequently, the electric motor control device 19 receives the operating state (acceleration, vehicle speed and gradient angle) from the engine control device 20 (step S6), and the supercharging pressure (necessary) required by the electric supercharger 5 based on the operating state. (Supercharging pressure) is calculated (step S7). Here, FIG. 4 shows an example of an operating state that is a reference for calculating the required supercharging pressure. FIG. 4 shows that the required supercharging pressure increases when the acceleration during acceleration is large, when the vehicle speed is high, and when the gradient angle is an upward gradient.

  Next, the electric motor control device 19 rotates the electric motor 9 in the supercharging direction according to the required supercharging pressure to supercharge intake air (step S8), and improves the output of the internal combustion engine 1, thereby improving the output of FIG. The process ends.

According to the control apparatus for an internal combustion engine according to the first embodiment of the present invention, the control means is a vehicle in which the driving state detected by the driving state detecting means is an acceleration unnecessary state that does not require acceleration of the vehicle. If the vehicle acceleration is negative, the vehicle speed is greater than the specified speed, the vehicle gradient angle is a downward gradient, the accelerator pedal is not depressed, etc. The intake air pressure is reduced by accelerating the electric motor of the electric supercharger in the direction opposite to the direction in which it is performed.
Therefore, even in an internal combustion engine equipped with an electric supercharger, the intake negative pressure can be increased during operation, and the pumping loss can be increased to improve the engine braking effectiveness. Further, by increasing the intake negative pressure during operation, it is possible to ensure the effect of the booster device that assists the braking force.
Further, by driving the electric motor in accordance with the differential pressure between the required brake negative pressure calculated by the control means and the intake pressure detected by the intake pressure detection means, the optimum required brake negative pressure can be ensured.

In the first embodiment, the electric supercharger 5 is provided between the intake passage 3 and the exhaust passage 4, and the turbine wheel 6 and the compressor wheel 8 are connected to each other by the rotating shaft 7. . However, the electric supercharger 5 is a so-called electric blower which is composed of a compressor wheel 8 and an electric motor 9 provided in the intake passage 3 and supercharges intake air only by electric energy. Also good.
Further, not only the electric supercharger 5 but also a mechanical supercharger may be further provided in the subsequent stage of the electric supercharger 5 to constitute a so-called twin charger.
In these cases, the same effect as in the first embodiment can be obtained.

In the first embodiment, the motor control device 19 and the engine control device 20 are described as separate units. However, the present invention is not limited to this. For example, when the functions can be integrated into the engine control device 20 or the like, the motor control device 19 may function as a simple driver that drives the motor 9.
Also in this case, the same effect as in the first embodiment can be obtained.

  In the first embodiment, the gasoline engine having the throttle valve 11 is described as an example of the internal combustion engine 1. However, the present invention is not limited to this, and the intake negative pressure can be increased during operation even in the internal combustion engine 1 that does not have the throttle valve 11 including the diesel engine.

1 is a configuration diagram illustrating an entire system including a control device for an internal combustion engine according to Embodiment 1 of the present invention. FIG. It is a flowchart which shows an example of operation | movement of the electric motor control apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows an example of the driving | running state used as the reference | standard of calculation of the brake required negative pressure in Embodiment 1 of this invention. It is explanatory drawing which shows an example of the driving | running state used as the reference | standard of calculation of the required supercharging pressure in Embodiment 1 of this invention. It is explanatory drawing which illustrates the relationship between an accelerator opening and intake negative pressure about the internal combustion engine provided with the electric supercharger, and the internal combustion engine which is not provided with the electric supercharger.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 3 Intake passage, 5 Electric supercharger, 9 Electric motor, 13 Intake pressure sensor (Intake pressure detection means), 17 Booster, 18 Piping, 19 Electric motor control apparatus (Control means, Accelerator operation detection means), 21 acceleration sensor (acceleration detection means), 22 vehicle speed sensor (vehicle speed detection means), 23 gradient sensor (gradient angle detection means), 24 accelerator pedal.

Claims (8)

Provided in the internal combustion engine mounted on the vehicle, the motor rotates the compressor wheel to supercharge the intake air drawn into the cylinder through the intake passage and in the opposite direction to the direction of supercharging the intake air An electric supercharger capable of reducing the intake pressure by accelerating the electric motor;
Driving state detecting means for detecting the driving state of the vehicle;
Control means for calculating a target supercharging pressure that is a target value of the intake pressure based on the operating state, and controlling the electric motor in accordance with the target supercharging pressure,
The control means stops the control of the electric motor according to the target supercharging pressure and accelerates the electric motor in the reverse direction when the driving state is an acceleration unnecessary state that does not require acceleration of the vehicle. A control device for an internal combustion engine.   The control means calculates a target negative pressure that is a target value of an intake negative pressure based on the operation state when the operation state is the acceleration unnecessary state, and controls the electric motor according to the target negative pressure. The control apparatus for an internal combustion engine according to claim 1, wherein: It further includes a booster that assists the braking force,
The control device for an internal combustion engine according to claim 1 or 2, wherein a pipe for introducing intake air to the booster is connected to the intake passage. The driving state detecting means includes acceleration detecting means for detecting acceleration of the vehicle,
4. The control device for an internal combustion engine according to claim 1, wherein the control unit determines that the acceleration is unnecessary when the acceleration is a negative value. 5. The driving state detection means includes vehicle speed detection means for detecting the vehicle speed of the vehicle,
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the control means determines that the acceleration is unnecessary when the vehicle speed is higher than a predetermined speed. The driving state detection unit includes a gradient angle detection unit that detects a gradient angle with respect to a traveling direction of the vehicle,
The internal combustion engine according to any one of claims 1 to 3, wherein the control means determines that the acceleration is unnecessary when the gradient angle is an angle indicating a downward gradient. Control device. The driving state detecting means includes an accelerator operation detecting means for detecting whether or not an accelerator pedal of the vehicle is depressed.
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the control means determines that the acceleration is not required when the accelerator pedal is not depressed. An intake pressure detecting means provided in the intake passage for detecting an intake pressure downstream of the electric supercharger;
The control device for an internal combustion engine according to any one of claims 1 to 7, wherein the control means feedback-controls the electric motor based on an intake pressure detected by the intake air detection means. .

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