JP2007224818A - Control device for internal combustion engine equipped with electric supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a favorable acceleration response by using pre-assist while avoiding useless electric power consumption in a control device for an internal combustion engine equipped with an electric supercharger. <P>SOLUTION: A motor 28 forcibly driving a turbocharger is provided. A foot position information detection part 54 detecting a foot position move time Tfoot during which a driver moves its foot from a brake pedal to an accelerator pedal is provided. When the foot position move time Tfoot is shorter than a pre-assist necessity determination value Tmin, namely, when the step change motion of the pedals is relatively quick and it is determined that an acceleration demand in an electric assist use range is issued after that, pre-assist is executed until the rotation speed Nt of the motor 28 reaches a motor rotation speed criterion Ntmin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine including an electric supercharger, and more particularly, to a control device for an internal combustion engine including an electric supercharger suitable as a device for controlling an internal combustion engine that performs pre-assist as necessary. .

  Conventionally, for example, Patent Document 1 discloses a control device for a turbocharger with an electric motor. In a vehicle equipped with a turbocharger with an electric motor, in order to improve the acceleration response of the vehicle to the depression of the accelerator pedal at the time of starting or reacceleration, the electric motor is driven prior to the driver's acceleration request, thereby A control for increasing the supercharging pressure before depressing, that is, pre-assist (flying boost-up control according to Patent Document 1) is known.

  In the above-mentioned Patent Document 1, it is determined whether or not the vehicle is in a state immediately before starting based on information such as vehicle speed, clutch, gear, and brake operation status, and from the time when the brake is released immediately before the start. The above pre-assist is executed. Then, the pre-assist amount is changed in accordance with the required time from the brake release time to the accelerator pedal depression time at the previous start. According to such a method, the pre-assist amount can be made appropriate according to the length of the required time.

Japanese Patent No. 3163846 Japanese Patent No. 3055143 JP-A-2-123242 JP-A-3-202630

  During the execution of the pre-assist, the electric power stored in the battery is consumed by driving the electric motor. For this reason, if pre-assist is executed but acceleration requiring electric assist is not required during the subsequent accelerator operation, pre-assist performed in advance is unnecessary. The required battery power is wasted power consumption.

  The present invention has been made to solve the above-described problems, and is an electric supercharger capable of obtaining a good acceleration response utilizing pre-assist while avoiding unnecessary power consumption. It aims at providing the control apparatus of an internal combustion engine provided with this.

A first aspect of the invention is an internal combustion engine control device that includes an electric supercharger and executes pre-assist driving the electric supercharger as necessary prior to an acceleration request from a driver,
Detection means for detecting the movement time when the driver moves his / her foot to the accelerator pedal;
Pre-assist necessity determination means for determining necessity of execution of the pre-assist based on a comparison result between the travel time detected by the detection means and a predetermined determination value;
It is characterized by providing.

According to a second invention, in the first invention, after the pre-assist is executed based on the determination result by the pre-assist necessity determining means, the electric assist using the electric supercharger is actually executed. Electric assist execution status determination means for determining whether or not
Determination value variable means for varying the determination value according to the execution status of the electric assist determined by the electric assist execution status determination means;
Is further provided.

  According to a third aspect of the present invention, in the first or second aspect, the determination value changing means changes the determination value to a larger value when the electric assist is actually executed. If not executed, the determination value is changed to a smaller value.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the electric supercharger is a turbocharger with an electric motor integrated with the turbocharger. To do.

  According to the first invention, the acceleration request from the driver can be predicted before the accelerator pedal is actually depressed. For this reason, pre-assist can be performed only in an appropriate situation, and good acceleration response using pre-assist can be obtained while avoiding useless power consumption.

  According to the second invention, an effective pre-assist success rate can be obtained by changing a determination value for determining whether or not to perform pre-assist depending on an execution state of the electric assist after the pre-assist is executed. It becomes possible to raise more.

  According to the third aspect, the determination value can be learned to an appropriate value.

  According to the fourth aspect of the invention, in the internal combustion engine including the turbocharger with electric motor, pre-assist can be performed only in an appropriate situation, and wasteful power consumption can be avoided.

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. An electric motor rotation speed sensor 30 that outputs a signal corresponding to the rotation speed (turbo rotation 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. Various actuators such as the throttle valve 20 and the bypass valve 34 are connected to the output side of the ECU 40, and the throttle position sensor 42, the accelerator opening as well as the air flow meter 18 and the supercharging pressure sensor 24 are connected to the input side of the ECU 40. Various sensors such as a degree sensor 44 and a crank angle sensor 46 are connected. The accelerator opening sensor 44 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 46 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 46, 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 diagram for explaining a specific system configuration around the ECU 40 shown in FIG. As shown in FIG. 2, the system of the present embodiment includes a DC power supply (battery) 48. The DC power source 48 is connected to an inverter 50 that converts DC power into AC power having a variable voltage and variable frequency. The inverter 50 is connected to the electric motor 28 and the ECU 40, respectively, and adjusts the drive current of the electric motor 28 according to the energization pattern output from the ECU 40. In addition, a rotation angle calculation circuit 52 is connected to the motor rotation speed sensor 30. The rotation angle calculation circuit 52 is connected to the ECU 40. Based on the output of the motor rotation speed sensor 30, the rotation angle and rotation speed of the motor 28 calculated by the rotation angle calculation circuit 52 are output to the ECU 40.

  The ECU 40 is connected to a foot position information detection unit 54 that detects the foot position information of the driver of the vehicle. FIG. 3 is a diagram illustrating a specific configuration example of the foot position information detection unit 54 illustrated in FIG. 2. More specifically, FIG. 3 shows a view of the brake pedal 56 and the accelerator pedal 58 viewed from the direction perpendicular to the tread surface of those pedals.

  The foot position information detector 54 of the present embodiment uses the optical sensor 60 to detect the driver's foot position information. The optical sensor 60 includes a light emitting element and a light receiving element (not shown). For example, an LED that emits infrared light can be used as the light emitting element, and a phototransistor can be used as the light receiving element, for example.

  As shown in FIG. 3, the optical sensor 60 is attached to a side surface of the brake pedal 56 that faces the accelerator pedal 58 and a side surface of the accelerator pedal 58 that faces the brake pedal 56. Although not shown here, each light sensor 60 is reflected on the instrument panel of the vehicle so that the light emitted from the light emitting element of the light sensor 60 is reflected and the light receiving element can receive the light. It is assumed that a reflecting plate is attached to each of the positions facing each other.

  According to the foot position information detection unit 54 configured as described above, when the driver moves his / her foot from the brake pedal 56 to the accelerator pedal 58 side, the light sensor 60 provided on the brake pedal 56 and the accelerator pedal 58 are provided. The light emitted from each of the photosensors 60 provided in is sequentially blocked. The light receiving element of the optical sensor 60 outputs a current proportional to the amount of light reflected by the reflecting plate.

  For this reason, it is possible to detect that the driver's foot has moved from the brake pedal 56 to the accelerator pedal 58 by detecting a current change in the light receiving element of the optical sensor 60 when the light is blocked. it can. Note that the detection method of the foot position information here is not limited to the above, but for example, from when the depression of the brake pedal 56 is released until the optical sensor 60 provided on the accelerator pedal 58 side detects the foot. It can also be the time.

[About supercharging using an electric supercharger]
According to the system of the present embodiment described above, when the exhaust energy of the internal combustion engine 10 is low, the electric motor 28 is driven using the accelerator opening, the engine speed Ne, and the like as parameters to eliminate the so-called turbo lag. Electric supercharging (herein referred to as “electric assist”) is performed. At this time, in the system of the present embodiment, before the acceleration request from the driver based on the operation of the accelerator pedal 58 is detected, the electric motor 28 is turned on in order to further improve the responsiveness of the electric supercharging using the electric motor 28. Control for increasing the supercharging pressure in advance by driving, that is, pre-assist is performed as necessary.

  More specifically, the pre-assist is executed with the bypass valve 34 in the middle of the intake bypass pipe 32 opened. That is, when the electric motor 28 is driven with the bypass valve 34 opened, the intake air compressed by the compressor 26 a is circulated between the intake pipe 14 and the intake bypass pipe 32. Therefore, before the acceleration request is detected, the rotational speed Nt of the electric motor 28 can be increased to a desired rotational speed in advance without greatly changing the intake air amount into the cylinder, and supercharging is performed in advance. The pressure can be increased.

During the execution of the pre-assist, the electric power stored in the battery 48 is consumed by driving the electric motor 28. For this reason, if pre-assist is executed but acceleration that requires motor assist is not required at the time of subsequent accelerator operation, pre-assist performed in advance is unnecessary. The required battery power is wasted power consumption.

  Therefore, in the system according to the present embodiment, it is determined whether or not the pre-assist needs to be executed according to the travel time when the driver moves his / her foot from the brake pedal 56 to the accelerator pedal 58.

[Specific Processing in Embodiment 1]
FIG. 4 is a flowchart of a routine executed by the ECU 40 in the first embodiment to realize the above function. In addition, this routine shall be started for every predetermined control period. In the routine shown in FIG. 4, first, foot position information is read based on the outputs of the two optical sensors 60 provided in the foot position information detection unit 54 (step 100). Next, based on the read foot position information, it is determined whether or not the pedal has been changed from the brake pedal 56 to the accelerator pedal 58 (step 102).

  If it is determined in step 102 that the pedal has been changed, the foot until the foot moves from the brake pedal 56 to the accelerator pedal is then determined based on the foot position information. The position movement time Tfoot is calculated (step 104).

  Next, it is determined whether or not the current engine speed Ne is greater than a predetermined engine speed limit value Nemax (step 106). The limit value Nemax is a threshold value for determining whether or not the current exhaust energy is sufficient to allow supercharging without requiring electric assist. As a result, when it is determined that Nemax <Ne is satisfied, that is, when it can be determined that the current exhaust energy is sufficient to perform the necessary supercharging without using the electric assist, the motor 28 is Not driven (step 108).

  On the other hand, if it is determined in step 106 that Nemax <Ne is satisfied, that is, if it is determined that it is necessary to use the electric assist when an acceleration request is issued from the driver, the electric motor 28 is then used. It is determined whether or not the rotational speed Nt is greater than a predetermined motor rotational speed determination value Ntmin (step 110). The determination value Ntmin is whether or not the current motor rotation speed Nt has reached a value at which supercharging using electric assist can be executed immediately when an electric assist drive command is issued thereafter, that is, A threshold for determining whether or not pre-assist is necessary. Note that the determination value Ntmin may be varied in accordance with the operating state of the internal combustion engine 10 and road conditions.

  If it is determined in step 110 that Ntmin <Nt is satisfied, that is, if it is determined that pre-assist is not necessary, the motor 28 is not driven (step 108). On the other hand, if it is determined that Ntmin <Nt does not hold, that is, if it is determined that pre-assist is necessary, then the foot position movement time Tfoot calculated in step 104 is the predetermined pre-assist requirement. It is determined whether or not it is smaller than the rejection determination value Tmin (foot position movement time control logic (step 112)).

  Even when it is determined in step 112 that Tmin> Tfoot is not satisfied, that is, when the driver depresses the brake pedal 56 to the accelerator pedal 58, the depressing operation is relatively slow. Therefore, if it can be determined that an acceleration request in the electric assist utilization range will not be issued thereafter, the electric motor 28 is not driven to perform pre-assist (step 108).

  On the other hand, if it is determined in step 112 that Tmin> Tfoot is satisfied, that is, it can be determined that an acceleration request in the electric assist utilization area is subsequently issued because the stepping operation of the pedal is relatively steep. In this case, pre-assist is executed until the rotational speed Nt of the electric motor 28 reaches the electric motor rotational speed determination value Ntmin (step 114).

  According to the routine shown in FIG. 4 described above, is the driver making an acceleration request using the electric assist based on the foot position movement time Tfoot in which the driver moves his foot from the brake pedal 56 to the accelerator pedal 58? It can be predicted before the accelerator pedal 58 is actually depressed. For this reason, pre-assist can be performed only in an appropriate situation. As a result, it is possible to obtain a good acceleration response utilizing pre-assist while avoiding unnecessary power consumption.

  Further, according to the method of the present embodiment, the current (immediately preceding) movement of the foot when the foot is moved to the accelerator pedal 58 side from the state where the foot is placed on the brake pedal 56 and the accelerator pedal 58 is depressed. Since the determination based on the speed is performed, it is possible to accurately predict whether or not the driver will subsequently request the electric assist.

  In the first embodiment described above, the ECU 40 executes the process of step 104, so that the “detecting means” in the first invention executes the process of step 112. The “pre-assist necessity determination means” in the present invention is realized.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to 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. 4 using the hardware configuration shown in FIG.

  When the system of the present embodiment performs control of the system of the first embodiment described above, the necessity of pre-assist is determined based on information on whether or not electric assist is actually executed after the start of pre-assist. This is characterized in that the determination value Tmin to be varied is varied.

[Specific Processing in Second Embodiment]
FIG. 5 is a flowchart of a routine executed by the ECU 40 in the second embodiment to realize the above function. In FIG. 5, the same steps as those shown in FIG. 4 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, after the pre-assist has been executed (step 114), whether or not the electric assist has actually been executed in accordance with the driver's pedal change operation that has motivated this pre-assist execution. Is determined (step 200). Whether or not the electric assist is executed is determined based on the accelerator opening (that is, the depression amount of the accelerator pedal 58) and the accelerator opening change rate (that is, the depression speed of the accelerator pedal). It can be determined by determining whether or not it is large.

  If it is determined in step 200 that the electric assist has been executed, it can be determined that the pre-assist has been executed correctly during the foot position movement time Tfoot at the time of starting the current routine. In this case, even if the foot position movement time Tfoot is larger than the current pre-assist necessity determination value Tmin, the driver can also determine that there is a possibility of requesting electric assist. Therefore, in this case, the pre-assist necessity determination value Tmin is changed to a larger value in order to further increase the pre-assist execution frequency after the next time (step 202).

  On the other hand, when it is determined in step 200 that the electric assist has not been executed, it can be determined that the pre-assist should not have been originally executed in the foot position movement time Tfoot at the time of starting the current routine. In other words, it can be determined that the current pre-assist necessity determination value Tmin is excessive. Therefore, in this case, the pre-assist necessity determination value Tmin is changed to a smaller value in order to reduce the frequency of pre-assist execution after the next time (step 204).

  According to the routine shown in FIG. 5 described above, it is possible to obtain information on whether or not the current pre-assist is actually necessary by determining whether or not the electric assist is performed after the pre-assist is executed. Then, by reflecting the information in the determination of the pre-assist necessity determination value Tmin, it is possible to further increase the effective pre-assist success rate as compared with the first embodiment described above. Further, according to the routine method described above, it is possible to accurately determine whether or not it is necessary to perform pre-assist by reflecting the habit of pedal operation of each driver.

  By the way, in Embodiment 2 mentioned above, in step 112 of the routine shown in FIG. 5, when the foot position movement time Tfoot is equal to or longer than the pre-assist necessity determination value Tmin, it is determined that pre-assist is unnecessary. (Step 108). At this time, it may be further determined whether or not the electric assist is actually executed after the driver's stepping operation of the pedal, which has been a motivation for the pre-assist determination. If it is confirmed that the electric assist is actually executed, it can be determined that the pre-assist should be executed, although the pre-assist is not executed this time. Therefore, in such a case, the pre-assist necessity determination value Tmin may be set longer than the current value.

  In the second embodiment described above, the ECU 40 executes the process of step 200, so that the “electric assist execution status determination means” in the second invention executes the processes of steps 202 and 204. Thus, the “judgment value varying means” in the second invention is realized.

  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 the present invention is a pre-assist. However, the present invention is not limited to this, and 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. FIG. 2 is a diagram for explaining a specific system configuration around an ECU shown in FIG. 1. It is a figure which shows the specific structural example of the foot position information detection part shown in FIG. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a flowchart of the routine performed in Embodiment 2 of this invention.

Explanation of symbols

10 Internal combustion engine 14 Intake pipe 26 Electric turbocharger (MAT)
26a Compressor 26b Turbine 28 Electric motor 30 Motor rotation speed sensor 32 Intake bypass pipe 34 Bypass valve 40 ECU (Electronic Control Unit)
48 DC power supply 54 Foot position information detector 56 Brake pedal 58 Accelerator pedal 60 Optical sensor
Nemax engine speed limit value
Ntmin Motor speed judgment value
Tfoot Foot position movement time
Tmin Pre-assist necessity judgment value

Claims (4)

A control device for an internal combustion engine that includes an electric supercharger, and executes pre-assist driving the electric supercharger as required prior to an acceleration request from a driver,
Detection means for detecting the movement time when the driver moves his / her foot to the accelerator pedal;
Pre-assist necessity determination means for determining necessity of execution of the pre-assist based on a comparison result between the travel time detected by the detection means and a predetermined determination value;
A control device for an internal combustion engine comprising an electric supercharger. Electric assist execution status determining means for determining whether or not electric assist using the electric supercharger is actually executed after the pre-assist is executed based on the determination result by the pre-assist necessity determining means; ,
Determination value variable means for varying the determination value according to the execution status of the electric assist determined by the electric assist execution status determination means;
The control device for an internal combustion engine provided with the electric supercharger according to claim 1.   The determination value variable means changes the determination value to a larger value when the electric assist is actually executed, and changes the determination value to a smaller value when the electric assist is not executed. A control device for an internal combustion engine comprising the electric supercharger according to claim 1 or 2.   The internal combustion engine with an electric supercharger according to any one of claims 1 to 3, wherein the electric supercharger is a turbocharger with an electric motor integrally formed with the turbocharger. Engine control device.

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