JP2007198253A - Device for controlling internal combustion engine provided with electric supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce useless electric power consumption while securing good transient response of torque at a time of acceleration in an internal combustion engine provided with an electric supercharger in relation to a device for controlling the internal combustion engine provided with the electric supercharger. <P>SOLUTION: A turbocharger with a motor is provided as an electric supercharger. A compressor of MAT is electrically driven and assist control of intake air quantity is started (step 104) when quick acceleration request is detected (step 102). When it is judged that actual intake air quantity reaches transient target value reducing predetermined quantity from target intake air quantity (step 106), operation of MAT 26 is immediately stopped (step 108). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including an electric supercharger.

  Conventionally, for example, Patent Document 1 discloses a supercharging device for an internal combustion engine including a turbocharger and an electric supercharger. At the time of acceleration where the engine speed does not increase easily, such as when traveling with a steep climb, the turbocharging effect by the turbocharger does not increase and the electric supercharger is operated for a long time. In this conventional apparatus, the operation of the electric supercharger is restricted so that the drive motor and battery of the electric supercharger are not overloaded under such a specific acceleration situation.

JP 2004-108152 A JP 2004-76687 A

  According to the above-described conventional device, it is possible to avoid that the driving of the electric supercharger adversely affects the battery under the specific acceleration condition described above. However, no particular limitation is imposed on the operation of the electric supercharger under other acceleration conditions. In other words, the above-described conventional apparatus still has room for examination in terms of effectively reducing the power consumption caused by driving the electric supercharger while ensuring a good transient response of the torque of the internal combustion engine during acceleration. It was something to leave.

  The present invention has been made to solve the above-described problems. In an internal combustion engine equipped with an electric supercharger, at the time of acceleration, while ensuring good transient response of torque, it reduces wasteful power consumption. It is an object of the present invention to provide a control device that can be used.

A first invention is a control device for an internal combustion engine comprising a turbocharger and an electric supercharger configured integrally or separately with the turbocharger,
Control means for controlling the electric supercharger based on a target intake air amount acquired according to the acceleration request degree,
The control means operates the electric supercharger under a predetermined acceleration condition, and when the actual intake air amount reaches a transient target value obtained by subtracting a predetermined amount from the target intake air amount, the electric supercharger The operation of is immediately stopped.

The second invention is a control device for an internal combustion engine comprising a turbocharger and an electric supercharger configured integrally or separately from the turbocharger,
Control means for controlling the electric supercharger based on a target intake air amount acquired according to the acceleration request degree,
The control means includes
Power control means for gradually reducing the drive power of the electric supercharger when the actual intake air amount has reached a transient target value obtained by subtracting a predetermined amount from the target intake air amount;
The electric supercharger is operated under a predetermined acceleration condition, and when the driving power of the electric supercharger is reduced to a predetermined power value by the power control means, the operation of the electric supercharger is immediately stopped. It is characterized by doing.

  According to a third aspect, in the second aspect, the predetermined power is determined based on a relationship between driving power of the electric supercharger and motor efficiency of the electric supercharger. To do.

  According to the first invention, it is necessary at the time of acceleration by executing supercharging using the electric supercharger until the actual intake air amount reaches a transient target value obtained by subtracting a predetermined amount from the target intake air amount. A minimum torque transient response can be ensured. In addition, when the above transient target value is reached, the operation of the electric supercharger can be stopped in a situation where the supercharging efficiency is relatively low by immediately stopping the operation of the electric supercharger. This can reduce wasteful power consumption.

  According to the second invention, it is necessary at the time of acceleration by executing supercharging using the electric supercharger until the actual intake air amount reaches a transient target value obtained by subtracting a predetermined amount from the target intake air amount. A minimum torque transient response can be ensured. Further, after reaching the above transient target value, the actual intake air amount gradually increases toward the target intake air amount due to the original supercharging of the turbocharger although there is a phase delay. According to the present invention, the driving power of the electric supercharger is gradually reduced according to such an increase in the actual intake air amount. Then, the operation of the electric supercharger is stopped when the driving power is reduced before the transition to the ineffective supercharging state. For this reason, according to the present invention, at the time of acceleration, it is possible to achieve both transient response of torque of the internal combustion engine and suppression of useless power consumption.

  According to the third invention, the predetermined power value for stopping the operation of the electric supercharger is determined based on the relationship between the drive power and the efficiency of the electric motor. As drive power decreases, motor efficiency also decreases. Under the situation where the motor efficiency is lowered, the electric supercharger is supercharged in a state where the battery power utilization efficiency is poor. According to the present invention, such a situation can be avoided and wasteful power consumption can be further suppressed.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10 having a plurality of cylinders (four cylinders in FIG. 1), an intake system that supplies air to the internal combustion engine 10, an exhaust system that exhausts exhaust gas from the internal combustion engine 10, And a control system for controlling the operation of the internal combustion engine 10. The internal combustion engine 10 is mounted on a vehicle and used as a power source.

  The intake system of the internal combustion engine 10 includes an intake manifold 12 and an intake pipe 14 connected to the intake manifold 12. Air is taken into the intake pipe 14 from the atmosphere and distributed to the combustion chambers of the respective cylinders via the intake manifold 12. An air cleaner 16 is attached to the inlet of the intake pipe 14. An air flow meter 18 that outputs a signal corresponding to the flow rate of air sucked into the intake pipe 14 is provided in the vicinity of the downstream side of the air cleaner 16.

  A throttle valve 20 is provided upstream of the intake manifold 12. An intercooler 22 that cools the compressed air is provided upstream of the throttle valve 20. Further, a supercharging pressure sensor 24 that outputs a signal corresponding to the pressure in the intake pipe 14 is disposed downstream of the throttle valve 20.

  In the middle of the intake pipe 14 from the air flow meter 18 to the throttle valve 20, a turbocharger with a motor (motor-assisted turbocharger, hereinafter referred to as MAT) 26 is provided. The MAT 26 includes a compressor 26a, a turbine 26b, and an electric motor 28 disposed between the compressor 26a and the turbine 26b. The compressor 26a and the turbine 26b are integrally connected by a connecting shaft, and the compressor 26a is rotationally driven by the exhaust energy of the exhaust gas input to the turbine 26b. The connecting shaft is also a rotor of the electric motor 28, and the compressor 26a can be forcibly driven by operating the electric motor 28. Further, a turbo rotational speed sensor 30 that outputs a signal corresponding to the rotational speed (turbo rotational speed) of the compressor 26a is attached to the connecting shaft.

  One end of an intake bypass pipe 32 is connected in the middle of the intake pipe 14 from the compressor 26 a to the intercooler 22. The other end of the intake bypass pipe 32 is connected to the upstream side of the compressor 26a. A bypass valve 34 for controlling the flow rate of the air flowing through the intake bypass pipe 32 is disposed in the intake bypass pipe 32. By operating the bypass valve 34 and opening the inlet of the intake bypass pipe 32, a part of the air compressed by the compressor 26a is returned again to the inlet side of the compressor 26a. When the turbocharger 26 is in an operating state in which a surge is likely to occur, the surge can be prevented by returning a part of the air exiting the compressor 26 a to the inlet side of the compressor 26 a through the intake bypass pipe 32.

  The exhaust system of the internal combustion engine 10 includes an exhaust manifold 36 and an exhaust pipe 38 connected to the exhaust manifold 36. The exhaust gas discharged from each cylinder of the internal combustion engine 10 is collected in the exhaust manifold 36 and is discharged to the exhaust pipe 38 via the exhaust manifold 36.

  The control system of the internal combustion engine 10 includes an ECU (Electronic Control Unit) 40 and a motor controller 42. The motor controller 42 controls the energization state of the electric motor 28 based on a command from the ECU 40. Electric power to the electric motor 28 is supplied from the battery 44. The ECU 40 is a control device that comprehensively controls the entire system shown in FIG.

  In addition to the motor controller 42, various actuators such as the throttle valve 20 and the bypass valve 34 are connected to the output side of the ECU 40. On the input side of the ECU 40, in addition to the air flow meter 18 and the boost pressure sensor 24, the throttle valve Various sensors such as a position sensor 46, an accelerator opening sensor 48, and a crank angle sensor 50 are connected. The turbo controller 30 is connected to the motor controller 42. The accelerator opening sensor 48 is a sensor that outputs a signal corresponding to a depression amount (accelerator opening) of an accelerator pedal (not shown), and the crank angle sensor 50 is a sensor that outputs a signal corresponding to the rotation angle of the crankshaft. is there. According to the output of the crank angle sensor 50, the engine speed NE [rpm] or the like can be detected. In addition to these devices and sensors, a plurality of devices and sensors are connected to the ECU 40, but the description thereof is omitted here. The ECU 40 drives each device according to a predetermined control program based on the output of each sensor.

  FIG. 2 is a time chart for explaining the cause of the time delay when the engine generated torque responds with a change in the accelerator opening when the internal combustion engine 10 is accelerated. More specifically, FIGS. 2A to 2D show temporal changes in the accelerator opening, the throttle opening, the intake air amount, and the engine generated torque in order from the top. As shown in FIG. 2 (A), when it is confirmed that the accelerator opening is depressed at time t0, a predetermined time (until the driving signal is transmitted from the ECU 40 to the throttle motor that drives the throttle valve 20). t1-t0) is required. Therefore, the throttle valve 20 does not react until the no-response time (t1-t0) has elapsed.

  There is also a delay time from when the throttle valve 20 starts to move until the required opening is reached. In FIG. 2, the throttle response time is evaluated based on whether or not the throttle valve 20 has responded to an opening degree of 63% of the required opening degree. According to this standard, a throttle response delay time (t2−t1) as shown in FIG. 2B exists as a delay time caused by the operating speed of the throttle valve 20.

  Further, as shown in FIG. 2C, there is an intake delay time (t3−t2) until intake air of an amount corresponding to the change of the throttle valve 20 is taken into the intake pipe 14. As shown in FIG. 2 (D), the combustion delay time (t4−t3) is also present after the response of the intake air and before the changed intake air amount is converted into the engine generated torque. Exists. These delay times are also based on the 63% response as described above.

  As described above, there is a total delay time (t4−t0) due to various response delay factors from when the accelerator pedal is depressed by the driver of the vehicle to when the engine torque is actually generated. Therefore, in order to improve the response of the internal combustion engine 10 during acceleration, it is necessary to improve these response delays. The system of the present embodiment includes a turbocharger 26 with an electric motor. According to the MAT 26, it is possible to increase the intake air amount with respect to the equal throttle opening. As a result, it is possible to improve the intake delay time among the response delays described above, and to improve the transient response with good torque.

  However, since the MAT 26 is driven by power supplied from the battery 44, it is desirable that consideration is given to the power consumption of the battery 44 when the MAT 26 is driven. Therefore, in the system according to the present embodiment, the ECU 40 performs the following routine processing shown in FIG. 3 in order to reduce excessive power consumption while ensuring a good torque transient response during acceleration using the MAT 26. I decided to let them.

[Specific Processing in Embodiment 1]
FIG. 3 is a flowchart of a routine executed by the ECU 40 in the first embodiment to achieve the above object. In the routine shown in FIG. 3, first, the accelerator opening, the accelerator opening change rate, and the engine speed are obtained (step 100).

  Next, it is determined whether or not a rapid acceleration request has been issued (step 102). Specifically, the currently requested acceleration is performed based on the accelerator opening (that is, the amount of depression of the accelerator pedal) and the rate of change of the accelerator opening (that is, the depression speed of the accelerator pedal) obtained in step 100 above. If it is going to be determined, it will be determined whether the rapid acceleration request | requirement was issued by determining whether an intake-air delay time will become more than the regulation value previously memorize | stored in ECU40.

  If it is determined in step 102 that a rapid acceleration request has not been issued, the processing of this routine is immediately terminated. On the other hand, under the predetermined acceleration condition in which it is determined that the sudden acceleration request is issued in step 102, the compressor 26a of the MAT 26 is driven electrically, and the intake air amount assist control is started (step 104). More specifically, the assist amount of the intake air amount by the MAT 26 is determined so that the target intake air amount calculated based on the degree of acceleration request is obtained, and the driving of the MAT 26 is performed so as to obtain the determined assist amount. Power is controlled. The acceleration request degree can be detected based on, for example, the accelerator opening and the accelerator opening change rate.

  Next, it is determined whether or not the actual intake air amount has reached a predetermined transient target value (step 106). The predetermined value used in the determination in step 106 is a transient target value obtained by subtracting a predetermined amount from the target intake air amount set in step 104. Here, for example, a value that is 63% of the target intake air amount Set to

  If it is determined in step 106 that the actual intake air amount has reached the predetermined value, the electric drive of the compressor 26a of the MAT 26 is stopped (step 108).

  FIG. 4 is a time chart for explaining the torque response at the time of acceleration of the internal combustion engine 10 improved by the processing of the routine shown in FIG. More specifically, FIG. 4 (A) to FIG. 4 (E) show temporal changes in the accelerator opening, the throttle opening, the intake air amount, and the engine generated torque in order from the top. According to the routine process shown in FIG. 3, the intake delay time is shortened from A (t3-t2) to B (t3'-t2) as shown in FIG. Improved. Along with this, the combustion delay time changes from C (t4−t3) to D (t4′−t3 ′). Therefore, according to the processing of the routine shown in FIG. 3, the total delay time during acceleration is shortened from E (t4-t0) to F (t4'-t0).

  As described above, according to the processing of the routine shown in FIG. 3, supercharging using the MAT 26 is executed until the actual intake air amount reaches the transient target value obtained by subtracting the predetermined amount from the target intake air amount. Thus, it is possible to ensure the minimum necessary torque transient response during acceleration. Further, when the transient target value is reached, the operation of the MAT 26 is stopped immediately, so that the operation of the MAT 26 under a situation where the supercharging efficiency is relatively low can be stopped. Power consumption can be suppressed.

  As described above, the method of the present embodiment is not intended to increase the maximum torque value of the internal combustion engine 10 by driving the MAT 26 at the time of acceleration, but by instantaneously generating the torque required by the driver. Only the transient response is improved. For this reason, as compared with the case where driving by the MAT 26 is executed without taking any consideration on power consumption, the surplus power consumption is effectively reduced while sufficiently securing the acceleration required by the driver. be able to.

  In the first embodiment described above, the “control means” according to the first aspect of the present invention is implemented when the ECU 40 executes the routine shown in FIG.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. 5 and FIG.
The system of the present embodiment can be realized by causing the ECU 40 to execute a routine shown in FIG. 5 described later instead of the routine shown in FIG. 3 using the hardware configuration shown in FIG.

  In the system of the present embodiment, unlike the system of the first embodiment described above, the driving of the MAT 26 is not stopped immediately when the actual intake air amount reaches a predetermined transient target value. It is characterized in that the driving power of the MAT 26 is gradually reduced as long as it is within a range that can be maintained at a value close to the target value.

[Specific Processing in Embodiment 1]
FIG. 5 is a flowchart of a routine executed by the ECU 40 in the second embodiment in order to realize the above function. In FIG. 5, the same steps as those shown in FIG. 3 in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 5, when it is determined that there is a sudden acceleration request from the driver and the intake air amount assist control by driving the MAT 26 is started (steps 100 to 104), then the air flow meter 18 or Based on the output of the supercharging pressure sensor 24, the actual intake air amount when the MAT 26 is driven is measured (step 200). Instead of measuring the actual intake air amount based on the sensor output, the intake air amount when the MAT 26 is driven may be estimated based on the calculation result of the air model provided in the ECU 40.

  Next, the actual intake air amount measured in step 200 is compared with the target intake air amount (set in the same manner as the target intake air amount in the routine shown in FIG. 3 described above), and the difference between these values is determined as a determination value. It is determined whether or not the value is greater than (step 202). According to the processing in this step 202, it is possible to determine whether or not the actual intake air amount has reached the transient target value.

  If it is determined in step 202 that the difference between the actual intake air amount and the target intake air amount is larger than the determination value, it is determined that the intake amount assist control by the MAT 26 is still required. Therefore, the driving power supplied to the compressor 26a of the MAT 26 is increased by a predetermined increment (step 204).

  On the other hand, if it is determined in step 202 that the difference between the actual intake air amount and the target intake air amount is equal to or less than the determination value, it is determined that the necessary minimum torque transient response is ensured. Therefore, the drive power supplied to the compressor 26a of the MAT 26 is reduced by a predetermined decrease (step 206).

  Next, it is determined whether or not the current driving power of the MAT 26 is smaller than a specified value (step 208). FIG. 6 is a graph showing the relationship between the driving power of the MAT 26, the turbo rotation speed, and the motor efficiency of the electric motor 28. As shown in FIG. 6, when the drive power amount of the MAT 26 is reduced, the turbo rotation speed is reduced and the motor efficiency of the electric motor 28 is reduced. Therefore, if the driving power of the MAT 26 is reduced by executing the processing of step 206, the supercharging using the battery power efficiently cannot be performed due to the reduction of the motor efficiency. The specified value in this step 208 is a value for determining whether or not such an effective supercharging can be performed. The prescribed value in step 208 may be a minimum driving power value for determining whether supercharging is possible by supplying driving power to the compressor 26a of the MAT 26.

  While it is not determined in step 208 that the current driving power of the MAT 26 is smaller than the specified value, the processing in steps 202 to 208 is continuously performed, while the driving power of the current MAT 26 is set to the specified value. If it is determined that the value is smaller than that, the electric drive of the compressor 26a of the MAT 26 is stopped (step 210).

  According to the routine shown in FIG. 5 described above, by performing supercharging using the MAT 26 until the actual intake air amount reaches a transient target value obtained by subtracting a predetermined amount from the target intake air amount, As a result, the minimum torque transient response can be ensured. Further, after reaching the above transient target value, the actual intake air amount gradually increases toward the target intake air amount due to the original supercharging of the turbocharger although there is a phase delay. According to the present invention, the driving power of the MAT 26 is gradually reduced in accordance with such an increase in the actual intake air amount. Then, the operation of the MAT 26 is stopped when the driving power is reduced before the transition to the ineffective supercharging state. For this reason, according to the present invention, at the time of acceleration, it is possible to achieve both transient response of torque of the internal combustion engine and suppression of useless power consumption.

  Further, according to the processing of the above routine, when the driving power is reduced to a state where effective supercharging cannot be performed based on the relationship between the driving power of the MAT 26 and the motor efficiency of the electric motor 28, the MAT 26 Is stopped. For this reason, useless power consumption can be further suppressed.

  In the second embodiment, the ECU 40 executes the routine shown in FIG. 5 so that the “control means” in the second invention executes the steps 202 and 206. Thus, the “power control means” in the second invention is realized. Further, the specified value used in the processing of step 208 corresponds to the “predetermined power value” in the second invention.

  By the way, in Embodiment 1 and 2 mentioned above, although the compressor 26a of the turbocharger 26 electrically driven by the electric motor 28 is provided as an electric supercharger, the electric supercharger in this invention is limited to this. For example, an electric compressor disposed in the middle of the intake pipe (intake passage) 14 and provided separately from the turbocharger may be used.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a time chart for demonstrating the factor of a time delay at the time of an engine generated torque responding with the change of an accelerator opening at the time of acceleration of an internal combustion engine. It is a flowchart of the routine performed in Embodiment 1 of the present invention. FIG. 4 is a time chart for explaining torque response at the time of acceleration of the internal combustion engine improved by processing of a routine shown in FIG. 3. FIG. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a figure showing the mutual relationship of the drive electric power of MAT, the turbo rotation speed, and the motor efficiency of an electric motor.

Explanation of symbols

10 Internal combustion engine 14 Intake pipe 20 Throttle valve 26 Turbocharger with electric motor (MAT)
26a Compressor 26b Turbine 28 Electric motor 38 Exhaust pipe 40 ECU (Electronic Control Unit)
42 Motor controller 44 Battery

Claims (3)

A control device for an internal combustion engine comprising a turbocharger and an electric supercharger configured integrally or separately from the turbocharger,
Control means for controlling the electric supercharger based on a target intake air amount acquired according to the acceleration request degree,
The control means operates the electric supercharger under a predetermined acceleration condition, and when the actual intake air amount reaches a transient target value obtained by subtracting a predetermined amount from the target intake air amount, the electric supercharger An internal combustion engine control device comprising an electric supercharger, characterized in that the operation of the engine is immediately stopped. A control device for an internal combustion engine comprising a turbocharger and an electric supercharger configured integrally or separately from the turbocharger,
Control means for controlling the electric supercharger based on a target intake air amount acquired according to the acceleration request degree,
The control means includes
Power control means for gradually reducing the drive power of the electric supercharger when the actual intake air amount has reached a transient target value obtained by subtracting a predetermined amount from the target intake air amount;
The electric supercharger is operated under a predetermined acceleration condition, and when the driving power of the electric supercharger is reduced to a predetermined power value by the power control means, the operation of the electric supercharger is immediately stopped. A control device for an internal combustion engine comprising an electric supercharger.   3. The internal combustion engine having an electric supercharger according to claim 2, wherein the predetermined electric power is determined based on a relationship between drive electric power of the electric supercharger and motor efficiency of the electric supercharger. Control device.

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