JP2004169673A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of suppressing output variation of the internal combustion engine in regenerative power generation time by a turbocharger with a motor. <P>SOLUTION: The control device of the internal combustion engine comprises the turbocharger 11 disposed incidentally to the internal combustion engine 1, the motor 11b capable of generating power by rotating a turbine/compressor 11a of the turbocharger 11 with exhaust flow, and an output increasing means for increasing the output of the internal combustion engine 1 during power generation by the motor 11b. As the output increasing means, a means for correcting the opening of a throttle valve 13 in the opening direction is used. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for an internal combustion engine having a turbocharger provided with an electric motor capable of generating electric power using the rotation of a turbine.
[0002]
[Prior art]
Attempts to obtain high output (or low fuel consumption) by supercharging the intake air of an engine (internal combustion engine) with a turbocharger have been conventionally used. One of the demands for the improvement of the turbocharger is that the boosting of the supercharging pressure in the low rotation speed range is poor, and the engine output characteristics in the low rotation speed range are not good. This is a phenomenon that occurs in a low rotation speed region where the exhaust energy is small due to the principle of the turbocharger in which the intake air is supercharged using the exhaust energy. In order to improve this, twin-turbo conversion and the like are generally performed, but an electric motor (motor) is incorporated in the turbine / compressor to forcibly drive the turbine / compressor to obtain a desired supercharging pressure. Attempts have been made. In such a case, it is also possible to make the electric motor perform regenerative power generation using the exhaust energy. As an internal combustion engine having such a turbocharger with a motor, there is one described in [Patent Document 1].
[0003]
[Patent Document 1]
JP-A-5-240058
[Problems to be solved by the invention]
In the internal combustion engine described in [Patent Document 1], when power is generated using a motor of a turbocharger with a motor, part of exhaust energy is consumed for power generation, and the supercharging effect is reduced accordingly. As a result, the output of the internal combustion engine decreases. [Patent Document 1] discloses that when power is generated by an electric motor attached to a turbocharger, power generation by an alternator is stopped to reduce the load on an internal combustion engine, but this is not a fundamental measure. Further improvement was desired.
[0005]
Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can suppress output fluctuation of the internal combustion engine during regenerative power generation for a turbocharger with a motor.
[0006]
[Means for Solving the Problems]
The control device for an internal combustion engine according to claim 1 includes a turbocharger disposed in association with the internal combustion engine, an electric motor capable of generating electricity by rotating a turbine / compressor of the turbocharger by an exhaust flow, and an electric motor. Output power increasing means for increasing the output of the internal combustion engine during power generation.
[0007]
According to a second aspect of the present invention, in the control device for an internal combustion engine according to the first aspect, when increasing the output of the internal combustion engine, priority is given to increasing the output by adjusting the opening of the throttle valve when increasing the output of the internal combustion engine. It is characterized by performing.
[0008]
According to a third aspect of the present invention, in the control device for an internal combustion engine according to the second aspect, when the opening of the throttle valve is fully opened, the output is increased by adjusting the fuel injection amount. Features.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the control device of the present invention will be described below. FIG. 1 shows an engine 1 having a control device according to the present embodiment.
[0010]
The engine 1 described in the present embodiment is a multi-cylinder engine, but here only one cylinder is shown in FIG. 1 as a cross-sectional view. The engine 1 is of a type in which fuel is injected into the upper surface of a piston 4 in a cylinder 3 by an injector 2. This engine 1 is capable of performing stratified combustion, and is a so-called lean burn engine. By supercharging a larger amount of intake air by a turbocharger described later and performing lean burn, not only high output but also low fuel consumption can be realized.
[0011]
The engine 1 compresses air sucked into the cylinder 3 through the intake passage 5 by the piston 4, injects fuel into a hollow formed on the upper surface of the piston 4, and moves a rich mixture to the vicinity of the ignition plug 7. It can be collected and ignited by the spark plug 7 to burn (stratified combustion). If fuel is injected during the intake stroke, normal homogeneous combustion can also be performed. The interior of the cylinder 3 and the intake passage 5 are opened and closed by an intake valve 8. The exhaust gas after combustion is exhausted to the exhaust passage 6. The interior of the cylinder 3 and the exhaust passage 6 are opened and closed by an exhaust valve 9. An air cleaner 10, an air flow meter 27, a turbo unit 11, an intercooler 12, a throttle valve 13, and the like are arranged on the intake passage 5 from the upstream side.
[0012]
The air cleaner 10 is a filter that removes dust and dirt from the intake air. The air flow meter 27 of the present embodiment is of a hot wire type, and detects an intake air amount as a mass flow rate. The turbo unit 11 is disposed between the intake passage 5 and the exhaust passage 6 and performs supercharging. In the turbo unit 11 of the present embodiment, the turbine-side impeller and the compressor-side impeller are connected by a rotating shaft (hereinafter, this portion is simply referred to as a turbine / compressor 11a).
[0013]
Further, the turbocharger of the present embodiment is a turbocharger with an electric motor in which the electric motor 11b is incorporated so that the rotation shaft of the turbine / compressor 11a becomes the output shaft. The motor 11b can also function as a generator that generates power using exhaust energy. The turbo unit 11 can function as a normal supercharger that performs supercharging only by exhaust energy, but can further perform supercharging by forcibly driving the turbine / compressor 11a by the electric motor 11b. .
[0014]
In addition, by using the exhaust energy, the electric motor 11b is rotated via the turbine / compressor 11a to generate regenerative electric power, and the generated electric power can be collected. The electric motor 11b has, as main components, a rotor fixed to the rotating shaft of the turbine / compressor 11a and a stator arranged around the rotor. On the downstream side of the turbo unit 11 on the intake passage 5, an air-cooled intercooler 12 that lowers the temperature of the intake air whose temperature has increased due to a pressure increase due to supercharging by the turbo unit 11 is arranged. The intercooler 12 lowers the temperature of the intake air to improve the charging efficiency.
[0015]
Downstream of the intercooler 12, a throttle valve 13 for adjusting the amount of intake air is arranged. The throttle valve 13 of the present embodiment is a so-called electronically-controlled throttle valve. The operation amount of an accelerator pedal 14 is detected by an accelerator positioning sensor 15, and the ECU 16 controls the throttle valve 13 based on the detection result and other information amounts. Is determined. The throttle valve 13 is opened and closed by a throttle motor 17 provided in association therewith. In addition to the throttle valve 13, a throttle positioning sensor 18 for detecting the opening degree is also provided.
[0016]
Downstream of the throttle valve 13, a pressure sensor 19 for detecting the pressure (supercharging pressure / intake pressure) in the intake passage 5 is provided. These sensors 15, 18, 19, 27 are connected to the ECU 16 and send the detection results to the ECU 16. The ECU 16 is an electronic control unit including a CPU, a ROM, a RAM, and the like. The above-described injector 2, the ignition plug 7, the electric motor 11b, and the like are connected to the ECU 16, and these are controlled by signals from the ECU 16. In addition, the ECU 16 is also connected to a hydraulic pressure of a variable valve timing mechanism 20 for controlling the opening / closing timing of the intake valve 8, a controller 21 connected to the electric motor 11b, a battery 22, and the like.
[0017]
The controller 21 not only controls the driving of the electric motor 11b, but also has a function as an inverter that performs voltage conversion of the electric power regenerated by the electric motor 11b. The power generated by the regenerative power generation is converted into a voltage by the controller 21 and then charged in the battery 22. On the other hand, on the exhaust passage 6, an air-fuel ratio sensor 28 that detects an exhaust air-fuel ratio is disposed upstream of the turbo unit 11. The air-fuel ratio sensor 28 is connected to the above-described ECU 16, and sends the detection result to the ECU 16.
[0018]
An exhaust purification catalyst 23 for purifying exhaust gas is attached downstream of the turbo unit 11. An EGR (Exhaust Gas Recirculation) passage 24 for recirculating exhaust gas from the exhaust passage 6 (upstream of the air-fuel ratio sensor 28) to the intake passage 5 (surge tank formed downstream of the pressure sensor 19). It is arranged. An EGR valve 25 for adjusting the amount of exhaust gas recirculation is mounted on the EGR passage 24. The opening control of the EGR valve 25 is also performed by the ECU 16 described above. A crank positioning sensor 26 that detects the rotational position of the crankshaft is attached near the crankshaft of the engine 1. The crank positioning sensor 26 can also detect the engine speed from the position of the crank position.
[0019]
The control in the above-described internal combustion engine will be described. FIG. 2 shows a flowchart of control in the present embodiment.
[0020]
First, it is determined whether there is a power generation request (step 200). The overall control of the engine 1 is performed by the ECU 16, and the control of the electric motor 11 b is cooperatively controlled by the ECU 16 and the controller 21. The ECU 16 determines the state of the engine 1 from information amounts such as an engine speed, an intake air amount, and a throttle opening detected by the various sensors described above, and determines whether to recover energy by performing regenerative power generation by the electric motor 11b. They also decide whether or not. When the ECU 16 determines that the electric motor 11b performs regenerative power generation, a power generation amount request command is generated, and the controller 21 or the like performs regenerative power generation by the motor 11b by the controller 21 or the like. In step 200, it is determined whether or not the power generation request command has been generated.
[0021]
When there is no power generation request, that is, when step 200 is denied, correction coefficients α and β described later are cleared (step 270), and regenerative power generation by the electric motor 11b is not performed (step 280). In step 280, when the regenerative power generation by the electric motor 11b has already been performed, the operation is stopped.
[0022]
On the other hand, if there is a power generation request, that is, if step 200 is affirmative, then, the engine speed is detected by the crank positioning sensor 26, and the engine load is changed to the intake air amount or the throttle opening (throttle positioning sensor 18). Is calculated (estimated). Note that the intake air amount is measured by the air flow meter 27 or estimated from the detection result of the pressure sensor 19. The throttle opening is detected by a throttle positioning sensor 18.
[0023]
After step 210, it is determined whether or not the detected throttle opening is fully open (step 220). If the determination in step 220 is negative, and the throttle valve 13 still has room to open its opening, the supercharging effect reduced by the power generation by the electric motor 11b is increased to increase the intake air amount (accordingly, the fuel may also increase. Is obtained, a throttle opening correction coefficient α is calculated (step 230). The throttle opening correction coefficient α is a coefficient for instructing the basic throttle opening to be increased by what percentage with respect to the basic throttle opening. It should be noted that other methods, such as correction with a correction value that simply indicates the increment of the opening degree, instead of the coefficient, may be adopted.
[0024]
The throttle opening correction coefficient α is stored in the ECU 16 as a two-dimensional map based on the engine speed and the engine load, and is calculated (determined) based on the engine speed and the engine load detected and calculated in step 210. ) Is done. The correction coefficient α is a value that increases the opening of the throttle valve 13 as the engine speed increases and the engine load increases. The correction coefficient α is determined in advance through an experiment as a value for compensating for a decrease in torque (output decrease) of the engine 1 when power generation is actually performed.
[0025]
After the correction coefficient α is calculated in step 230, the opening of the throttle valve 13 is corrected to the opening side by reflecting the correction coefficient, and at the same time, the regenerative power generation by the electric motor 11b is started. By correcting the throttle valve 13 to the open side, the output of the engine 1 is corrected to the increase side. As a result, the amount of the supercharging effect reduced by the regenerative power generation is negated, and the regenerative power generation by the electric motor 11b can be started smoothly without generating a step or the like in the output of the engine 1.
[0026]
Particularly, here, priority is given to increasing the opening degree of the throttle valve 13 to increase the intake air amount. By doing so, the fuel injection amount is increased based on the optimum air-fuel ratio corresponding to the increased intake air amount, so that the output of the engine 1 increases. That is, the output can be increased while maintaining the optimum air-fuel ratio, and the supercharging effect reduced by the regenerative power generation can be effectively canceled. Here, the throttle valve 13, the ECU 16, the throttle motor 17, the throttle positioning sensor 18 and the like function as output increasing means.
[0027]
On the other hand, if step 220 is affirmative and the throttle valve 13 is fully opened, the fuel increase correction coefficient β is calculated to compensate for the supercharging effect reduced by the power generation by the electric motor 11b by increasing the fuel injection amount (step). 250). The fuel increase correction coefficient β is a coefficient for instructing the basic fuel injection amount to be increased by what percentage with respect to the basic fuel injection amount. It should be noted that other methods, such as correction using a correction value that simply indicates the increment of the injection amount instead of the coefficient, may be adopted.
[0028]
The fuel increase correction coefficient β is also stored in the ECU 16 as a two-dimensional map based on the engine speed and the engine load, and is calculated (determined) based on the engine speed and the engine load detected and calculated in step 210. Is done. The correction coefficient β also takes a value that increases the injected fuel amount as the engine speed is higher and the engine load is higher. The correction coefficient β is also determined in advance through experiments as a value for compensating for a decrease in torque (output decrease) of the engine 1 when power is actually generated.
[0029]
After the correction coefficient β is calculated in step 250, the correction coefficient is reflected to correct the fuel injection amount to be increased, and at the same time, the regenerative power generation by the electric motor 11b is started. The output of the engine 1 is corrected to the increasing side by correcting the fuel injection amount to the increasing side. As a result, the amount of the supercharging effect reduced by the regenerative power generation is negated, and the regenerative power generation by the electric motor 11b can be started smoothly without generating a step or the like in the output of the engine 1. Here, the ECU 16 and the like that determine the fuel injection amount function as output increasing means.
[0030]
In the above-described embodiment, the output is increased by adjusting the intake air amount via the throttle valve opening, and the output is increased by increasing the fuel injection amount (when the throttle is fully opened). Used together. However, only the adjustment of the intake air amount via the throttle valve opening may be employed alone. In this case, when the throttle valve is fully open, a step may be allowed to occur in the output of the internal combustion engine, and when the throttle valve is fully open, regenerative power generation by the electric motor of the turbocharged motor May be prohibited.
[0031]
In the embodiment described above, the pressure sensor 19 and the air flow meter 27 are used together. However, if a system for estimating the intake air amount from the intake pipe internal pressure can be constructed, the air flow meter 27 does not necessarily have to be provided. Alternatively, if control can be performed only by the air flow meter 27, the pressure sensor 19 may not be provided. In the above-described embodiment, the correction amount of the electric motor 11b during regenerative power generation (the amount of output increase that compensates for the loss due to regenerative power generation) is determined based on the engine speed and the engine load, but other parameters are used. Or by using them together.
[0032]
【The invention's effect】
The control device for an internal combustion engine according to the present invention includes an output increasing unit that increases the output of the internal combustion engine when the electric motor generates electric power. The output of the internal combustion engine is increased to compensate for This makes it possible to smoothly perform regenerative power generation without lowering the output of the internal combustion engine and without causing a step or the like in the output of the internal combustion engine accompanying regenerative power generation. Here, by increasing the output by adjusting the opening of the throttle valve when increasing the output of the internal combustion engine, the output can be increased while maintaining the optimum air-fuel ratio. . Further, when the opening of the throttle valve is fully opened, the output of the internal combustion engine can be further increased if the output increasing means increases the output by adjusting the fuel injection amount.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an internal combustion engine having one embodiment of a control device of the present invention.
FIG. 2 is a flowchart of internal combustion engine control during regenerative power generation according to an embodiment of the control device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Injector, 3 ... Cylinder, 4 ... Piston, 5 ... Intake passage, 6 ... Exhaust passage, 7 ... Spark plug, 8 ... Intake valve, 9 ... Exhaust valve, 10 ... Air cleaner, 11 ... Turbo unit, 11a: Turbine, 11b: Electric motor, 12: Intercooler, 13: Air cleaner, 13: Throttle valve, 14: Accelerator pedal, 15: Accelerator positioning sensor, 16: ECU, 17: Throttle motor, 18: Throttle positioning sensor, 19: Pressure Sensors, 20: variable valve timing mechanism, 21: controller, 22: battery, 23: exhaust purification catalyst, 24: EGR passage, 25: EGR valve, 26: crank positioning sensor, 27: air flow meter, 28: air-fuel ratio sensor.

Claims (3)

A control device for an internal combustion engine, comprising: a turbocharger disposed in association with the internal combustion engine; and an electric motor capable of generating electricity by rotating a turbine / compressor of the turbocharger by an exhaust gas flow.
A control device for an internal combustion engine, further comprising output increasing means for increasing the output of the internal combustion engine when the electric motor generates electric power. 2. The control device for an internal combustion engine according to claim 1, wherein when increasing the output of the internal combustion engine, the output increasing means gives priority to increasing the output by adjusting the opening degree of a throttle valve. 3. 3. The control device for an internal combustion engine according to claim 2, wherein the output increasing means increases the output by adjusting a fuel injection amount when the throttle valve is fully opened.

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