JP4075596B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine having a turbocharger equipped with a generator 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 intake air of an engine (internal combustion engine) with a turbocharger have been in common use. One of the demands for improvement of the turbocharger is that the boost pressure in the low rotation range is poor and the engine output characteristics in the low rotation range are not good. This is a phenomenon that occurs in a low rotation range where there is little exhaust energy due to the principle of turbocharger that uses exhaust energy to supercharge intake air.
[0003]
In order to improve this, twin turbocharger is generally used. However, a motor (turbo motor) is incorporated in the turbine / compressor to forcibly drive the turbine / compressor to obtain a desired boost pressure. Attempts have also been made. In such a case, it is possible to cause the turbo motor to perform regenerative power generation using the exhaust energy. The turbo motor at this time functions as a generator. As an internal combustion engine having such a turbocharger with a motor, there is one as described in [Patent Document 1].
[0004]
In recent years, an internal combustion engine that attempts to improve fuel efficiency and output with a lean burn engine has been put into practical use. The lean burn engine normally performs lean combustion with an air-fuel ratio of 20 or more, and super lean combustion with an air-fuel ratio of about 40 is possible by stratified combustion. In such a lean burn engine, it is normal that combustion at an air-fuel ratio of about 16 to 18 is not performed even in lean combustion. This is because combustion at an air-fuel ratio of about 16 to 18 not only provides little improvement in fuel efficiency but also increases the amount of nitrogen oxides NOx in the exhaust gas, so there is little merit. Even in lean combustion with an air-fuel ratio of 20 or more, the amount of NOx generated increases, but if it is in this region, there is a merit because a fuel efficiency improvement effect can be obtained, and the generated excess NOx is purified using a NOx adsorbent or the like.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-240058 [0006]
[Problems to be solved by the invention]
When regenerative power generation is performed using a turbocharger with a motor, power generation is performed with a part of the exhaust energy, and the supercharging effect is reduced accordingly. For this reason, when regenerative power generation is performed with a motor turbo during a lean burn in an internal combustion engine that has a turbocharger with a motor and is capable of lean burn, the amount of supercharged air is reduced and the air-fuel ratio during lean burn is slightly reduced. There is a concern of shifting to combustion at an air-fuel ratio (about 16 to 18) that has almost no merit as described above (shifting to the rich side). Accordingly, an object of the present invention is to provide a control device for an internal combustion engine capable of operating in a well-balanced manner the energy efficiency improvement by power generation in a turbocharger with a generator and the fuel efficiency improvement performance by lean burn.
[0007]
[Means for Solving the Problems]
The control apparatus for an internal combustion engine according to claim 1 includes a turbocharger attached to the internal combustion engine, a generator capable of generating power by rotating a turbine / compressor of the turbocharger by an exhaust flow, Generator control means for controlling the power generation of the generator, and the generator control means has an air-fuel ratio close to the theoretical air-fuel ratio as a result of the air-fuel ratio after power generation by the generator becoming rich due to power generation by the generator. An operation in which regenerative power generation is continuously performed while feedback control of the fuel ratio is performed, and a leaner side than a value close to the stoichiometric air-fuel ratio, and the amount of nitrogen oxides generated by engine combustion is below a predetermined air-fuel ratio exceeding a predetermined amount run selectively in accordance with the air-fuel ratio after the power generation by the power generator and operation to reduce the generation amount of the generator when it is predicted that some cases or the predetermined air-fuel ratio or less It is characterized in that. It should be noted that the “reduction” mentioned here naturally includes complete stoppage. Further, in the case based on the prediction, the “reduction” referred to here includes a case where power generation is performed with a reduced power generation amount and a case where power generation is not performed.
[0008]
Also, an invention according to claim 2, in the control apparatus for an internal combustion engine according to claim 1, the nitrogen oxide content is and sets the 18 fuel ratio greater than a predetermined amount.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the control device of the present invention will be described below. An engine 1 having a control device of the present embodiment is shown in FIG.
[0010]
The engine 1 described in the present embodiment is a multi-cylinder engine, but only one cylinder is shown in FIG. 1 as a sectional view. The engine 1 is a type of engine in which fuel is injected onto the upper surface of a piston 4 in a cylinder 3 by an injector 2. The engine 1 is capable of stratified combustion and is a so-called lean burn engine. By supercharging more intake air with a turbocharger, which will be described later, and performing lean burn, it is possible to achieve higher output in addition to lower fuel consumption.
[0011]
The engine 1 compresses the air sucked into the cylinder 3 through the intake passage 5 by the piston 4, and injects fuel into a recess formed in the upper surface of the piston 4 to bring a rich air-fuel mixture near the spark plug 7. These can be collected and ignited by a spark plug 7 and burned (stratified combustion). If fuel is injected during the intake stroke, normal homogeneous combustion can also be performed. An intake valve 8 opens and closes the inside of the cylinder 3 and the intake passage 5. The exhaust gas after combustion is exhausted to the exhaust passage 6. An exhaust valve 9 opens and closes the inside of the cylinder 3 and the exhaust passage 6. On the intake passage 5, 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 from the upstream side.
[0012]
The air cleaner 10 is a filter that removes dust and dirt in the intake air. The air flow meter 27 of this embodiment is of a hot wire type and detects the amount of intake air 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]
Moreover, the turbocharger of this embodiment is a turbocharger with a motor in which a turbomotor 11b is incorporated so that the rotating shaft of the turbine / compressor 11a becomes an output shaft. It is possible to assist supercharging by driving the turbo motor 11b. The turbo motor 11b can also function as a generator that generates power using exhaust energy, and is sometimes called a motor generator because it has the functions of a motor and a generator. The turbo unit 11 can also function as a normal turbocharger that performs supercharging only with exhaust energy without being assisted by the turbo motor 11b. The turbo motor 11b has a rotor fixed to the rotating shaft of the turbine / compressor 11a and a stator disposed around the rotor as main components.
[0014]
On the downstream side of the turbo unit 11 on the intake passage 5, an air-cooled intercooler 12 is disposed that lowers the temperature of the intake air whose temperature has increased as the pressure has increased due to supercharging by the turbo unit 11. The temperature of the intake air is lowered by the intercooler 12 to improve the filling efficiency. A throttle valve 13 that adjusts the amount of intake air is disposed downstream of the intercooler 12.
[0015]
The throttle valve 13 of the present embodiment is a so-called electronically controlled throttle valve, and an operation amount of the accelerator pedal 14 is detected by an accelerator positioning sensor 15, and the ECU 16 detects the throttle valve 13 based on this detection result and other information amounts. Is determined. The throttle valve 13 is opened and closed by a throttle motor 17 that is provided in association therewith. Further, a throttle positioning sensor 18 that detects the opening degree of the throttle valve 13 is also provided.
[0016]
A pressure sensor 19 for detecting the pressure (supercharging pressure / intake pressure) in the intake passage 5 is disposed on the downstream side of the throttle valve 13. These sensors 15, 18, 19, and 27 are connected to the ECU 16, and the detection results are sent to the ECU 16. The ECU 16 is an electronic control unit that includes a CPU, a ROM, a RAM, and the like. The ECU 16 is connected to the injector 2, the spark plug 7, the turbo motor 11b, and the like described above, and these are controlled by signals from the ECU 16.
[0017]
In addition to this, the hydraulic pressure of the variable valve timing mechanism 20 that controls the opening / closing timing of the intake valve 8, the controller 21 connected to the turbo motor 11 b, the battery 22, and the like are also connected to the ECU 16. The controller 21 not only controls the drive of the turbo motor 11b, but also has a function as an inverter that converts the direct current of the battery 22 into an alternating current and applies it to the turbo motor 11b. The turbo motor 11b also has a function as a rectifier that performs AC-DC conversion of the electric power regeneratively generated. The ECU 16 and the controller 21 control the power generation (and drive) of the turbo motor and function as a generator control means.
[0018]
An air-fuel ratio sensor 28 that detects the exhaust air-fuel ratio is disposed on the exhaust passage 6 upstream of the turbo unit 11. The air-fuel ratio sensor 28 of this embodiment is a so-called linear air-fuel ratio sensor that can linearly detect the exhaust air-fuel ratio of the exhaust gas. The air-fuel ratio sensor 28 is connected to the ECU 16 described above, and the detection result is sent to the ECU 16. Further, an exhaust purification catalyst 23 for purifying exhaust gas is attached to the downstream side 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 portion formed downstream of the pressure sensor 19) is provided. It is arranged.
[0019]
On the EGR passage 24, an EGR valve 25 for adjusting the exhaust gas recirculation amount is attached. The opening degree control of the EGR valve 25 is also performed by the ECU 16 described above. A crank positioning sensor 26 for detecting the rotational position of the crankshaft is attached in the vicinity of the crankshaft of the engine 1. The crank positioning sensor 26 can also detect the engine speed from the position of the crank position.
[0020]
Control in the above-described internal combustion engine will be described. FIG. 2 shows a flowchart of control in the first embodiment.
[0021]
First, it is determined whether or not a regenerative power generation condition is satisfied (step 200). If the regenerative power generation condition is satisfied, it can be said that there is a power generation request. The overall control of the engine 1 is performed by the ECU 16, and the control of the turbo 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 the information amount such as the engine speed, the intake air amount, and the throttle opening detected by the various sensors described above, and recovers energy by performing regenerative power generation with the turbo motor 11b. It is also judged whether or not.
[0022]
Specific examples of conditions that constitute the regeneration conditions include the following. ○ The accelerator pedal is not depressed [Because it is not when the output is maintained or increased, it is in a state suitable for generating electricity with exhaust energy and collecting it as electrical energy]. ○ The throttle opening is fully open [even if part of the exhaust energy is not supercharged but generated for power generation, it is in an allowable state for output]. The temperature of the turbo motor 11b is equal to or lower than a predetermined temperature [there is no risk of overheating even if regenerative power generation is performed]. The regenerative power generation conditions are composed of such conditions.
[0023]
When the regenerative power generation condition is not satisfied, that is, when step 200 is denied, the regenerative power generation by the turbo motor 11b is not performed, and the control of the flowchart of FIG. On the other hand, when the ECU 16 determines that the regenerative power generation condition is satisfied, the regenerative power generation by the turbo motor 11b is executed (step 210). By executing the regenerative power generation, a part of the exhaust energy for rotating the turbine / compressor 11a is used for power generation, so that the supercharging effect is reduced and the intake air amount is reduced. As a result, the air-fuel ratio shifts slightly to the rich side.
[0024]
Therefore, after the regenerative power generation is performed, the exhaust air / fuel ratio is detected by the air / fuel ratio sensor 29 (step 220), and it is determined whether or not the detected air / fuel ratio is 18 or less (step 230). The air-fuel ratio 18 in step 230 is set as an air-fuel ratio in which the amount of nitrogen oxides NOx generated by the combustion of the engine 1 exceeds a predetermined amount. If the air-fuel ratio exceeds 18 in step 230, the fuel efficiency improvement effect is obtained, and the control of the flowchart shown in FIG. That is, in this case, the regenerative power generation remains as it is. On the other hand, if the air-fuel ratio is 18 or less in step 230, it is next determined whether or not the air-fuel ratio is 16 or less (step 240).
[0025]
If step 230 is positive and step 240 is negative, 16 <detected air-fuel ratio ≦ 18. In this case, as described above, since there is not so much improvement in fuel efficiency and the amount of exhausted NOx increases, regenerative power generation by the turbo motor 11b is stopped (step 260). When the regenerative power generation causes the air-fuel ratio to become richer and falls within the above-described range (16 <detected air-fuel ratio ≦ 18) (when regenerative power generation is performed during lean burn, etc.), the fuel efficiency improvement effect is achieved. In this case, the regenerative power generation is stopped because the exhausted NOx amount increases.
[0026]
In step 260, the power generation amount may be merely reduced instead of stopping the power generation. When the power generation amount is reduced, the exhaust energy corresponding to that amount is used for supercharging, so the intake air amount increases and the air-fuel ratio shifts to the lean side. In order to reduce the regenerative power generation amount of the turbo motor 11b, for example, the power generation amount can be reduced by repeating the power generation state and the non-power generation state (duty control is performed) as compared with the case where the power generation state continues.
[0027]
On the other hand, when step 230 is affirmed and step 240 is also affirmed, the detected air-fuel ratio is 16 or less. In this case, the air-fuel ratio becomes close to the stoichiometric value as a result of the air-fuel ratio becoming richer due to regenerative power generation. In such a case, air-fuel ratio feedback control is performed so that the air-fuel ratio becomes stoichiometric, and regenerative power generation control is left as it is (step 250). As a result, energy is recovered by regenerative power generation, and the exhaust gas purification rate is achieved by reacting hydrocarbon HC and carbon monoxide CO to be oxidized in exhaust gas with NOx to be reduced in exhaust gas without excess and deficiency by stoichiometric combustion. Can be maintained well.
[0028]
In the first embodiment described above, when the detected air-fuel ratio is equal to or lower than the predetermined air-fuel ratio (18), if the air-fuel ratio is in the vicinity of the stoichiometry, the regenerative power generation is left as it is, and the air-fuel ratio feedback is made with the stoichiometric target air-fuel ratio. It moved to. Here, if the detected air-fuel ratio is equal to or lower than the predetermined air-fuel ratio (18), regenerative power generation may always be stopped (or the power generation amount is reduced). FIG. 3 shows a flowchart of the control (second embodiment) in this case. Since Step 300 to Step 330 are exactly the same as Step 200 to Step 230 in the first embodiment described above, description thereof is omitted.
[0029]
In step 330, if the air-fuel ratio exceeds 18, a fuel efficiency improvement effect is obtained. Therefore, the control of the flowchart shown in FIG. On the other hand, when the air-fuel ratio is 18 or less in step 330, there is not much fuel efficiency improvement effect and the amount of exhausted NOx increases, so regenerative power generation by the turbo motor 11b is stopped (step 340). In this way, it is possible to suppress deterioration in fuel efficiency and increase in NOx emissions by regenerative power generation. Alternatively, it may be determined whether lean burn is being performed before step 330, and step 330 may be executed only during lean burn. In step 340, the power generation amount may be reduced instead of stopping the power generation.
[0030]
In the first and second embodiments described above, the exhaust air-fuel ratio is directly detected by the air-fuel ratio sensor 29 after actually performing regenerative power generation, and control is performed based on the detected air-fuel ratio. However, instead of directly detecting the air-fuel ratio, control may be performed based on the air-fuel ratio estimated by estimating from various information amounts. The third embodiment described below is a case where control based on the estimated air-fuel ratio is used. FIG. 4 shows a flowchart of this control. In the third embodiment, the air-fuel ratio after regenerative power generation is predicted (estimated), and regenerative power generation may not be performed depending on the predicted air-fuel ratio. Hereinafter, the control of the third embodiment will be described.
[0031]
First, it is determined whether or not a regenerative power generation condition is satisfied (step 400). The regenerative power generation condition is as described in the description of the control of the first embodiment. When the regenerative power generation condition is not satisfied, that is, when step 400 is denied, the regenerative power generation by the turbo motor 11b is not performed, and the control of the flowchart of FIG. 4 ends. On the other hand, when the ECU 16 determines that the regenerative power generation condition is satisfied, first, the crank positioning sensor 26 detects the engine speed at that time and calculates the engine load (step 410). The engine load is calculated based on the intake air amount and the throttle opening. 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.
[0032]
Based on the detected and calculated engine speed and engine load, the air-fuel ratio (reproduced air-fuel ratio) when regenerative power generation is executed is predicted from the map (step 420). Examples of this map are shown in FIGS. 5 (a) and 5 (b). These maps are two-dimensional maps that determine the predicted air-fuel ratio from the engine speed and the engine load, and the predicted air-fuel ratio value is mapped based on the experimental value that is actually generated.
[0033]
Here, FIG. 5A shows a case where the turbocharger has a small supercharging capacity, and FIG. 5B shows a case where the supercharging capacity is large. As can be seen from FIG. 5 (a), when the supercharging capacity is small, the air-fuel ratio decreases as the engine speed increases. This is because, when the supercharging capacity is small, when the engine speed increases, the supercharging cannot catch up and the intake air amount tends to be insufficient, and the air-fuel ratio tends to be small (to the rich side). In FIG. 5A, the air-fuel ratio decreases as the engine load increases. This is because the fuel injection amount increases even when the intake air amount of the engine 1 becomes maximum (= constant).
[0034]
On the other hand, as can be seen from FIG. 5 (b), when the supercharging capacity is large, the air-fuel ratio decreases as the engine speed decreases. This is because when the supercharging capacity is large, the inertial mass of the turbine / compressor 11a is large, and when the engine speed is low, sufficient supercharging cannot be performed and the intake air amount becomes insufficient, and the air-fuel ratio is small ( This is because they tend to be richer. In FIG. 5B as well, the air-fuel ratio decreases as the engine load increases. This is also because the fuel injection amount increases even when the intake air amount of the engine 1 becomes maximum (= constant).
[0035]
Alternatively, a graph as shown in FIG. 6 may be used instead of FIG. 5A or FIG. 5B (it may be calculated as a calculation formula). In the graph shown in FIG. 6, the post-power generation air-fuel ratio is predicted only from the engine load. In FIG. 6, the air-fuel ratio decreases as the engine load increases. This is also because the fuel injection amount increases even when the intake air amount of the engine 1 becomes maximum (= constant) as described above.
[0036]
However, the accuracy in predicting the air-fuel ratio after execution of power generation from only the engine load as shown in FIG. 6 is the accuracy when predicting from the engine speed and engine load as shown in FIGS. 5 (a) and 5 (b). Inferior to accuracy. For this reason, here, even if it is predicted that the air-fuel ratio is 18 in the map of FIG. The engine load region corresponding to (range Y in FIG. 6) is provided as a region for reducing the regenerative power generation amount (which is wider than the range X corresponding to the predicted air-fuel ratio 16 to 18).
[0037]
After step 420, it is determined whether the predicted post-power generation air-fuel ratio is 18 or less (step 430). The air-fuel ratio 18 in step 430 is set as an air-fuel ratio in which the amount of nitrogen oxides NOx generated by the combustion of the engine 1 exceeds a predetermined amount. If the predicted air-fuel ratio exceeds 18 in step 430, regenerative power generation is executed as it is because the fuel efficiency improvement effect is obtained (step 440). On the other hand, if step 430 is positive, it is next determined whether or not the predicted air-fuel ratio is 16 or less (step 450).
[0038]
If step 430 is positive and step 450 is negative, 16 <predicted air / fuel ratio ≦ 18 [in the case of FIG. 5 (a) and FIG. 5 (b), the hatched area, in the case of FIG. The corresponding range]. In this case, as described above, even if regenerative power generation is executed, the fuel efficiency improvement effect is not so much and the amount of exhausted NOx increases, so regenerative power generation by the turbo motor 11b is not performed (step 470). When regenerative power generation is performed, the air-fuel ratio is close to rich and is predicted to be within the above-described range (16 <detected air-fuel ratio ≦ 18) (when regenerative power generation is being performed during lean burn or the like) When regenerative power generation is executed, it is predicted that the fuel efficiency improvement effect cannot be obtained and the amount of exhausted NOx increases. In this case, regenerative power generation is not performed.
[0039]
In step 470, the power generation may not be performed at all, but may be performed after the power generation amount is reduced. If the power generation amount is reduced, the exhaust energy corresponding to that amount is used for supercharging, so the intake air amount increases and the air-fuel ratio shifts to the lean side. The specific method for reducing the regenerative power generation amount of the turbo motor 11b is the same as that described in the first embodiment.
[0040]
On the other hand, when step 430 is affirmed and step 450 is also affirmed, the predicted air-fuel ratio is 16 or less. In this case, it is predicted that when regenerative power generation is performed, the air-fuel ratio becomes closer to a rich value and close to the stoichiometric air-fuel ratio (stoichiometry). In such a case, regenerative power generation is executed while performing air-fuel ratio feedback control so that the air-fuel ratio becomes stoichiometric after execution of regenerative power generation (step 460). In this way, energy is recovered by regenerative power generation, and hydrocarbon HC and carbon monoxide CO to be oxidized in exhaust gas and NOx to be reduced in exhaust gas are reacted without excess and deficiency by stoichiometric combustion. The exhaust gas purification rate can be maintained satisfactorily.
[0041]
In the above-described third embodiment, when the predicted air-fuel ratio is equal to or lower than the predetermined air-fuel ratio (18), if the predicted air-fuel ratio is close to the stoichiometry, air-fuel ratio feedback with the stoichiometric target air-fuel ratio is performed, Regenerative power generation was executed. Here, when the predicted air-fuel ratio is equal to or lower than the predetermined air-fuel ratio (18), regenerative power generation may not be performed (or performed after the power generation amount is reduced). FIG. 7 shows a flowchart of the control (fourth embodiment) in this case. Since Step 700 to Step 740 are exactly the same as Step 400 to Step 440 in the third embodiment described above, description thereof is omitted.
[0042]
In step 730, if the predicted air-fuel ratio is 18 or less, even if regenerative power generation is performed, it is predicted that there will be no significant improvement in fuel efficiency and the amount of exhausted NOx will increase. Is not performed (step 750). In this way, there is no occurrence of deterioration in fuel efficiency and increase in NOx emissions due to regenerative power generation. Note that it may be determined whether lean burn is being performed before step 730, and step 730 may be executed only during lean burn. Further, in step 750, the power generation may not be executed, but may be executed after reducing the power generation amount.
[0043]
In each of the embodiments described above, when the air-fuel ratio is detected after performing regenerative power generation, the target power generation amount at the time of performing regenerative power generation is determined using the map of FIG. 5 (a) or FIG. 5 (b). We are using. That is, first, based on the map of FIG. 5 (a) or FIG. 5 (b), a power generation amount with a predicted air-fuel ratio slightly higher than 18 is acquired, and the power generation amount is set as a target power generation amount to execute regenerative power generation. (Steps 210, 310, etc.). Then, the actual air-fuel ratio is detected after regenerative power generation, and the amount of power generation is reduced depending on the detected actual air-fuel ratio (steps 260, 340, etc.).
[0044]
In addition, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the pressure sensor 19 and the air flow meter 27 are used together. However, the airflow meter 27 is not necessarily provided as long as a system that estimates the intake air amount from the intake pipe internal pressure can be constructed. Alternatively, if control is possible only with the air flow meter 27, the pressure sensor 19 need not be provided.
[0045]
【The invention's effect】
The control device for an internal combustion engine according to the present invention reduces the amount of power generated by the generator (including the case of stopping) when the air-fuel ratio after power generation by the generator is equal to or lower than a predetermined air-fuel ratio. Alternatively, when the air-fuel ratio after power generation by the generator is predicted to be equal to or lower than the predetermined air-fuel ratio, power generation is executed by reducing the power generation amount by the generator (including the case where it is not executed). By doing in this way, the energy efficiency improvement by power generation with a turbocharger with a generator and the fuel efficiency improvement performance by lean burn can be operated in a well-balanced manner.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an internal combustion engine (engine) having an 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 the first embodiment of the control device of the present invention.
FIG. 3 is a flowchart of internal combustion engine control during regenerative power generation according to the second embodiment of the control device of the present invention.
FIG. 4 is a flowchart of internal combustion engine control during regenerative power generation according to a third embodiment of the control device of the present invention.
FIGS. 5A and 5B are maps for obtaining an air-fuel ratio from the engine load and the engine speed. FIG. 5A shows a case where the capacity of the turbo unit is small, and FIG.
FIG. 6 is a graph showing the relationship between air-fuel ratio and engine load.
FIG. 7 is a flowchart of internal combustion engine control during regenerative power generation according to a fourth 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 ... turbo 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 sensor, 20 ... Variable valve timing mechanism, 21 ... Controller, 22 ... Battery, 23 ... Exhaust gas purification catalyst, 24 ... EGR passage, 25 ... EGR valve, 26 ... Crank positioning sensor, 27 ... Air flow meter, 28 ... Air-fuel ratio sensor .

Claims (2)

A turbocharger attached to the internal combustion engine, a generator capable of generating power by rotating a turbine / compressor of the turbocharger by an exhaust flow, and a generator control means for controlling power generation of the generator Prepared,
The generator control means feedback-controls the air-fuel ratio at a value close to the stoichiometric air-fuel ratio as a result of the air-fuel ratio after power generation by the generator becoming richer as a result of power generation by the generator and continues to execute regenerative power generation And when the amount of nitrogen oxides generated by the combustion of the internal combustion engine is less than a predetermined air-fuel ratio exceeding a predetermined amount or less than a predetermined air-fuel ratio. When it is predicted that there is an engine, an operation for reducing the amount of power generated by the generator is selectively executed according to an air-fuel ratio after power generation by the generator . 2. The control apparatus for an internal combustion engine according to claim 1 , wherein the air-fuel ratio at which the nitrogen oxide amount exceeds a predetermined amount is set as 18.

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