JP4661633B2 - Internal combustion engine control device - Google Patents

Description

  The present invention relates to an internal combustion engine control device that adjusts the amount of fuel supplied to an internal combustion engine so that the air-fuel ratio of the internal combustion engine becomes a target air-fuel ratio and performs variable valve timing control.

  Conventionally, a three-way catalyst that oxidizes and reduces unnecessary components such as carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) contained in exhaust gas discharged from an internal combustion engine is disposed in the exhaust system. Therefore, it is widely known to reduce unnecessary components contained in the exhaust gas and to provide oxygen concentration sensors on the upstream side and the downstream side of the three-way catalyst and control the air-fuel ratio based on the detection values of these sensors. ing.

  In the above-described three-way catalyst, carbon monoxide or hydrocarbons contained in the exhaust gas react with water (H 2 O) to cause a water gas reaction that generates hydrogen (H 2) and carbon dioxide (CO 2). On the downstream side of the three-way catalyst, the hydrogen concentration tends to increase.

  Furthermore, since hydrogen has a higher diffusion rate than oxygen, the hydrogen concentration becomes high, which prevents oxygen from reaching the oxygen concentration sensor, and the detection value of the oxygen concentration sensor provided downstream of the three-way catalyst. However, since it becomes lower than the actual oxygen concentration, the accuracy of the air-fuel ratio control is lowered.

In order to cope with the influence of this water gas reaction, for example, the most upstream detection means for detecting the oxygen concentration upstream of the catalyst means provided in the exhaust system of the internal combustion engine and the oxygen concentration downstream of the catalyst means are detected. The most downstream detection means, the target air-fuel ratio setting means for setting the target air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine, and the output of the most upstream detection means so that the air-fuel ratio of the air-fuel mixture matches the target air-fuel ratio. The target air-fuel ratio that is set by the target air-fuel ratio setting means is corrected according to the output of the most downstream detection means only when the output of the feedback control means that performs feedback control and the output of the most downstream detection means exceeds a predetermined value. And a fuel ratio correction unit that corrects the target air-fuel ratio in consideration of deterioration in the accuracy of oxygen concentration detection due to the influence of hydrogen generated by the water gas reaction occurring in the catalyst unit ( In example, see Patent Document 1).
JP 2001-182595 A

  However, in such a conventional technique, variable valve timing control (variable valve timing control, hereinafter simply referred to as “VVT control”) for adjusting the opening / closing timing of the intake valve and the exhaust valve in accordance with the rotational speed of the internal combustion engine. When applied to an internal combustion engine, there is a problem that the target air-fuel ratio cannot be optimally corrected because the hydrogen concentration of the exhaust gas changes according to the operating state of the VVT control.

  The present invention has been made to solve the conventional problems, and provides an internal combustion engine control apparatus capable of optimally correcting a target air-fuel ratio even when VVT control is performed on the internal combustion engine. Objective.

An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus that adjusts the amount of fuel supplied to the internal combustion engine so that the air-fuel ratio of the internal combustion engine becomes a target air-fuel ratio. A valve adjusting means for adjusting an opening / closing timing of at least one of the valves in accordance with an operating state of the internal combustion engine; and according to an amount of hydrogen in the exhaust gas based on an opening / closing timing of at least one of the intake valve and the exhaust valve. A correction amount determining unit that determines a correction amount of the target air-fuel ratio; and a target air-fuel ratio correcting unit that corrects the target air-fuel ratio based on the correction amount.

  With this configuration, the internal combustion engine control apparatus according to the present invention corrects the target air-fuel ratio according to the amount of hydrogen in the exhaust gas calculated based on the opening / closing timing of the intake valve and the exhaust valve, so that the VVT control is performed on the internal combustion engine. Even in the case of applying, the target air-fuel ratio can be optimally corrected.

The internal combustion engine controller according to the present invention includes an opening / closing timing detecting means for detecting the opening / closing timing, and the correction amount determining means is configured to detect hydrogen in exhaust gas based on the opening / closing timing detected by the opening / closing timing detecting means. The correction amount of the target air-fuel ratio may be determined in accordance with the amount of .

  With this configuration, the internal combustion engine control apparatus of the present invention corrects the target air-fuel ratio in accordance with the amount of hydrogen in the exhaust gas calculated based on the actual opening / closing timing of the intake valve and the exhaust valve. Even when VVT control is performed, the target air-fuel ratio can be optimally corrected.

The correction amount determination means may determine the correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas based on the target amount of the opening / closing timing adjusted by the valve adjustment means. .

  With this configuration, the internal combustion engine control device of the present invention corrects the target air-fuel ratio in accordance with the amount of hydrogen in the exhaust gas calculated based on the target amount of the opening / closing timing of the intake valve and the exhaust valve. Even when the VVT control is applied to the target air-fuel ratio, the target air-fuel ratio can be optimally corrected.

  Further, the internal combustion engine control device of the present invention represents a correspondence between the opening / closing timing and the correction amount of the target air-fuel ratio determined according to the amount of hydrogen in the exhaust gas calculated based on the opening / closing timing. Correction amount map storage means for storing a correction amount map may be provided, and the correction amount determination means may determine the correction amount of the target air-fuel ratio based on the correction amount map.

  With this configuration, the internal combustion engine controller according to the present invention sets the target air-fuel ratio based on the correction amount map determined according to the amount of hydrogen in the exhaust gas calculated based on the opening / closing timing of the intake valve and the exhaust valve. Therefore, even when VVT control is applied to the internal combustion engine, the target air-fuel ratio can be optimally corrected.

  The valve adjusting means may adjust the opening / closing timing in accordance with the rotational speed and load factor of the internal combustion engine.

  Further, the correction amount determination means includes an intake valve control amount that represents a difference between a phase of the opening / closing timing of the intake valve and a reference angle, and an exhaust valve control that represents a difference between the phase of the opening / closing timing of the exhaust valve and a reference angle. The correction amount of the target air-fuel ratio may be determined using at least one of the amount as the opening / closing timing.

  Here, the correction amount determining means may set the reference angle of the phase of the intake valve as the most retarded angle and the reference angle of the phase of the exhaust valve as the most advanced angle.

The internal combustion engine control method according to the present invention is the internal combustion engine control method for adjusting the amount of fuel supplied to the internal combustion engine so that the air-fuel ratio of the internal combustion engine becomes a target air-fuel ratio. A valve adjustment step for adjusting an opening / closing timing of at least one of the intake valve and the exhaust valve according to an operating state of the internal combustion engine, and a correction amount determination means based on the opening / closing timing of at least one of the intake valve and the exhaust valve. A correction amount determining step for determining a correction amount of the target air-fuel ratio in accordance with the amount of hydrogen in the exhaust gas, and a target air-fuel ratio in which the target air-fuel ratio correction means corrects the target air-fuel ratio based on the correction amount A correction step.

  By this method, the target air-fuel ratio is corrected according to the amount of hydrogen in the exhaust gas calculated based on the opening / closing timing of the intake valve and the exhaust valve. Therefore, even when VVT control is performed on the internal combustion engine, the target air-fuel ratio is corrected. The air-fuel ratio can be optimally corrected.

In the internal combustion engine control method according to the present invention, the opening / closing timing detection includes an opening / closing timing detection step for detecting the opening / closing timing, and in the correction amount determination step, the correction amount determination means includes the opening / closing timing detection step. The target air-fuel ratio correction amount may be determined according to the amount of hydrogen in the exhaust gas based on the detected opening / closing timing.

  Even when VVT control is applied to the internal combustion engine, this method corrects the target air-fuel ratio in accordance with the amount of hydrogen in the exhaust gas calculated based on the actual opening / closing timing of the intake valve or the exhaust valve. The target air-fuel ratio can be optimally corrected.

In the correction amount determination step, the correction amount determination means sets the correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas based on the target amount of the opening / closing timing adjusted in the valve adjustment step. It may be determined .

  In this method, the VVT control is applied to the internal combustion engine in order to correct the target air-fuel ratio according to the amount of hydrogen in the exhaust gas calculated based on the target amount of the opening / closing timing of the intake valve or the exhaust valve. In addition, the target air-fuel ratio can be corrected optimally.

  In addition, a correction amount map representing the correspondence between the opening / closing timing and the correction amount of the target air-fuel ratio determined according to the amount of hydrogen in the exhaust gas calculated based on the opening / closing timing is stored in a storage medium. In the correction amount determination step, the correction amount determination means may determine the correction amount of the target air-fuel ratio based on the correction amount map.

  By this method, the VVT control is performed on the internal combustion engine in order to correct the target air-fuel ratio based on the correction amount map determined in accordance with the amount of hydrogen in the exhaust gas calculated based on the opening / closing timing of the intake valve or the exhaust valve. Even in the case of applying, the target air-fuel ratio can be optimally corrected.

  In the valve adjustment step, the valve adjustment means may adjust the opening / closing timing according to the rotational speed and load factor of the internal combustion engine.

  In the correction amount determination step, the correction amount determination means includes an intake valve control amount that represents a difference between the phase of the opening / closing timing of the intake valve and a reference angle, and the phase and reference angle of the opening / closing timing of the exhaust valve. The correction amount of the target air-fuel ratio may be determined using at least one of the exhaust valve control amount representing the difference between the two as the opening / closing timing.

  Here, in the correction amount determination step, the correction amount determination means may set the reference angle of the phase of the intake valve as the most retarded angle and the reference angle of the phase of the exhaust valve as the most advanced angle.

  The present invention can provide an internal combustion engine control apparatus that can optimally correct a target air-fuel ratio even when VVT control is performed on an internal combustion engine.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, an engine to which the internal combustion engine control device according to the present invention is applied will be described.

  As shown in FIG. 1, the engine 1 is constituted by a multi-cylinder internal combustion engine mounted on a vehicle, and a combustion chamber 4 partitioned by a piston 3 is formed in each cylinder 2. The cylinder 2 has an injector 5 for injecting fuel into the combustion chamber 4, a spark plug 6 provided so that an electrode portion is exposed in the combustion chamber 4, and a stroke of the piston 3, that is, the engine 1. There are provided an intake valve 9 and an exhaust valve 10 respectively linked to cams 7 and 8 that respond to rotation.

  The piston 3 is configured to rotationally drive the crankshaft 11, and an engine speed sensor 12 that detects the speed of the engine 1 is provided in the vicinity of the crankshaft 11. Further, rotation angle sensors 13 and 14 for detecting the rotation angle of the cams 7 and 8 are provided in the vicinity of the cams 7 and 8, respectively.

  The intake valve 9 is configured to open and close so as to communicate or block the intake pipe 15 for guiding air to the combustion chamber 4 and the combustion chamber 4. There is provided a throttle valve 16 for adjusting the amount of the engine according to the operation of an accelerator pedal (not shown). Further, the intake pipe 15 is provided with an intake pressure sensor 17 that detects the atmospheric pressure in the intake pipe 15 and a throttle position sensor 18 that detects the opening of the throttle valve 16.

  The exhaust valve 10 opens and closes so that the exhaust chamber 19 for exhausting the exhaust gas generated in the combustion chamber 4 and the combustion chamber 4 communicate with each other. A three-way catalyst 20 that purifies carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) contained therein, and an upstream O2 sensor that detects an oxygen (O2) concentration upstream of the three-way catalyst 20 21 and a downstream O2 sensor 22 for detecting the oxygen concentration downstream of the three-way catalyst 20 are provided.

  Further, as shown in FIG. 2, the engine 1 is provided with an ECU (Engine Control Unit) 23. The ECU 23 is connected to various sensors such as an engine speed sensor 12, rotation angle sensors 13 and 14, an intake pressure sensor 17, a throttle position sensor 18, an upstream O2 sensor 21, and a downstream O2 sensor 22.

  The ECU 23 includes a CPU (Central Processing Unit) 24, a RAM (Random Access Memory) 25, and a ROM (Read Only Memory) 26. When the CPU 24 reads the program stored in the ROM 26 into the RAM 25 and executes the program read into the RAM 25, the ECU 23 performs the injector 5, spark plug 6, cam 7, 8 controls each part of the engine 1 such as the hydraulic controllers 27 and 28 and the throttle valve 16.

  In particular, the ECU 23 adjusts the engine speed detected by the engine speed sensor 12, the opening of the throttle valve 16 detected by the throttle position sensor 18, or the air pressure in the intake pipe 15 detected by the intake pressure sensor 17. A target amount corresponding to the operating state of the engine 1 such as the load of the engine 1 determined based on the temperature and the temperature of the engine 1 measured by a water thermometer (not shown) is calculated, and the cams 7 and 8 are controlled by controlling the hydraulic controllers 27 and 28. VVT control is performed to adjust the opening / closing timings of the intake valve 9 and the exhaust valve 10 by adjusting so that the phase of the valve becomes the target amount.

  Further, as shown in FIG. 3A, the ROM 26 of the ECU 23 has an air-fuel ratio map representing a target air-fuel ratio according to the engine speed detected by the engine speed sensor 12 and the load of the engine 1. Is remembered. In FIG. 3A, the target air-fuel ratios A to D satisfy A> B> C> D. In particular, when the purpose is stoichiometric combustion, the target air-fuel ratios A to D desirably satisfy 15 ≧ A> B> C> D ≧ 14.

  The ECU 23 corrects the target air-fuel ratio determined by the air-fuel ratio map based on a change over time such as a change amount per unit time of the oxygen concentration detected by the downstream O2 sensor 22 and an operation amount of the VVT control. It is supposed to be. Further, the ECU 23 adjusts the fuel injection time by the injector 5 so that the air-fuel ratio in the combustion chamber 4 calculated based on the oxygen concentration detected by the upstream O2 sensor 21 becomes the corrected target air-fuel ratio. Thus, the amount of fuel supplied to the combustion chamber 4 is adjusted.

  Here, the operation amount of the VVT control refers to the intake valve control amount that represents the phase of the opening / closing timing of the intake valve 9 by the advance angle from the most retarded angle that is the reference angle, and the phase of the opening / closing timing of the exhaust valve 10 as the reference angle. This is the exhaust valve control amount expressed by the retard angle from the most advanced angle. The ECU 23 calculates the intake valve control amount and the exhaust valve control amount from the rotation angles of the cams 7, 8 detected by the rotation angle sensors 13, 14, respectively.

  Further, in the ROM 26 of the ECU 23, as shown in FIG. 3B, the correspondence between the intake valve control amount (IN.VVT) and the exhaust valve control amount (Ex.VVT) and the target air-fuel ratio correction amount is shown. A correction amount map is stored. In FIG. 3B, correction amounts E to I satisfy 1 ≧ E> F> G> H> I ≧ 0.95.

  This correction amount map is determined according to the amount of hydrogen in the exhaust gas calculated based on the intake valve control amount and the exhaust valve control amount. For example, the upstream O2 sensor 21 when the VVT control is not performed and It is determined by experimentally obtaining a correction amount that compensates for changes in the outputs of the upstream O2 sensor 21 and the downstream O2 sensor 22 when the VVT control is performed on the output of the downstream O2 sensor 22.

  The ECU 23 determines a correction amount for the target air-fuel ratio based on this correction amount map, and corrects the target air-fuel ratio with the determined correction amount.

  As described above, the rotation angle sensors 13 and 14 constitute opening / closing timing detection means for detecting the opening / closing timing of the intake valve 9 and the exhaust valve 10, and the ECU 23 includes the valve adjustment means for performing VVT control and the correction amount map. The correction amount map storing means for storing, the correction amount determining means for determining the correction amount of the target air-fuel ratio, and the target air-fuel ratio correcting means for correcting the target air-fuel ratio are configured.

  With respect to the engine 1 configured as described above, the correction operation of the target air-fuel ratio by the ECU 23 will be described with reference to FIG.

  First, the ECU 23 selects a target air-fuel ratio corresponding to the rotational speed of the engine 1 and the load of the engine 1 on the air-fuel ratio map stored in the ROM 26 of the ECU 23, and the selected target air-fuel ratio is selected from the downstream O2 sensor 22. The base target air-fuel ratio a corrected based on the change over time of the oxygen concentration detected by the above is calculated (S1).

  Next, the ECU 23 selects a correction amount b corresponding to the intake valve control amount and the exhaust valve control amount on the correction amount map (S2), and multiplies the selected correction amount b by the base target air-fuel ratio a. The target air-fuel ratio a is corrected, and the fuel injection time by the injector 5 is adjusted using the corrected base target air-fuel ratio a × b as the target air-fuel ratio (S3).

  The engine 1 according to the embodiment of the present invention corrects the target air-fuel ratio according to the amount of hydrogen in the exhaust gas calculated based on the opening / closing timings of the intake valve 9 and the exhaust valve 10. Even when the VVT control is performed on the target 1, the target air-fuel ratio can be optimally corrected.

  In the present embodiment, the ECU 23 is described as adjusting the opening / closing timing of the intake valve 9 and the exhaust valve 10, but in the present invention, the opening / closing timing of either the intake valve 9 or the exhaust valve 10 is set. You may make it adjust.

  Further, in the present embodiment, the ECU 23 has been described as determining the correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas calculated based on the intake valve control amount and the exhaust valve control amount. However, when the amount of hydrogen in the exhaust gas exhausted by the engine 1 varies depending on the intake valve control amount regardless of the exhaust valve control amount, the ECU 23 calculates the exhaust gas in the exhaust gas calculated based on the intake valve control amount. The target air-fuel ratio correction amount may be determined according to the amount of hydrogen.

  On the other hand, when the amount of hydrogen in the exhaust gas exhausted by the engine 1 varies depending on the exhaust valve control amount regardless of the intake valve control amount, the ECU 23 calculates the exhaust gas in the exhaust gas calculated based on the exhaust valve control amount. The target air-fuel ratio correction amount may be determined according to the amount of hydrogen.

  Further, in the present embodiment, the ECU 23 determines the correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas calculated based on the operation amount of the VVT control detected by the rotation angle sensors 13 and 14. In the present invention, the correction amount of the target air-fuel ratio may be determined according to the amount of hydrogen in the exhaust gas calculated based on the target amount of VVT control.

  In the present embodiment, the ECU 23 has been described as determining the correction amount of the target air-fuel ratio using the correction amount map. However, in the present invention, the ECU 23 determines the amount of exhaust gas from the operating amount of VVT control and the target amount. The amount of hydrogen may be calculated, and the target air-fuel ratio correction amount may be determined according to the calculated amount of hydrogen.

  Further, in the present embodiment, the target air-fuel ratio is corrected based on the temporal change such as the amount of change per unit time of the oxygen concentration detected by the downstream O2 sensor 22 and the operating amount of the VVT control, The present invention relates to an engine that adjusts the fuel injection time by the injector 5 so that the air-fuel ratio in the combustion chamber 4 calculated based on the oxygen concentration detected by the upstream O2 sensor 21 becomes the corrected target air-fuel ratio. Although an example in which the internal combustion engine control device is applied has been described, the internal combustion engine control device according to the present invention can be applied to any internal combustion engine that performs air-fuel ratio control using an O2 sensor.

1 is a block diagram of an engine according to an embodiment of the present invention. The block diagram of the control circuit of the engine in one embodiment of the present invention The table which shows the example of the air fuel ratio map and correction amount map which are referred by ECU which comprises the engine in one embodiment of this invention The flowchart for demonstrating the correction | amendment operation | movement of the target air fuel ratio of the engine in one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 3 Piston 4 Combustion chamber 5 Injector 6 Spark plug 7, 8 Cam 9 Intake valve 10 Exhaust valve 11 Crankshaft 12 Engine speed sensor 13, 14 Rotation angle sensor 15 Intake pipe 16 Throttle valve 17 Intake pressure sensor 18 Throttle Position sensor 19 Exhaust pipe 20 Three-way catalyst 21 Upstream O2 sensor 22 Downstream O2 sensor 23 ECU
24 CPU
25 RAM
26 ROM
27, 28 Hydraulic controller

Claims (9)

In the internal combustion engine control device for adjusting the amount of fuel supplied to the internal combustion engine so that the air-fuel ratio of the internal combustion engine becomes a target air-fuel ratio,
A valve adjusting means for adjusting an opening / closing timing of at least one of an intake valve and an exhaust valve of the internal combustion engine according to an operating state of the internal combustion engine;
Correction amount determining means for determining a correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas based on the opening / closing timing of at least one of the intake valve and the exhaust valve;
An internal combustion engine control apparatus comprising: a target air-fuel ratio correcting unit that corrects the target air-fuel ratio based on the correction amount. An opening / closing timing detecting means for detecting the opening / closing timing;
The correction amount determination unit determines the correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas based on the opening / closing timing detected by the opening / closing timing detection unit. The internal combustion engine control apparatus described.   The correction amount determination unit determines the correction amount of the target air-fuel ratio according to the amount of hydrogen in the exhaust gas based on the target amount of the opening / closing timing adjusted by the valve adjustment unit. 2. The internal combustion engine control device according to 1. A correction amount map storage means for storing a correction amount map representing a correspondence between the opening / closing timing and a correction amount of the target air-fuel ratio determined according to the amount of hydrogen in the exhaust gas based on the opening / closing timing;
2. The internal combustion engine control apparatus according to claim 1, wherein the correction amount determination means determines a correction amount of the target air-fuel ratio based on the correction amount map.   2. The internal combustion engine according to claim 1, wherein the correction amount determination unit determines a correction amount of the target air-fuel ratio that is determined in advance according to the amount of hydrogen in the exhaust gas based on the opening / closing timing. Engine control device.   6. The internal combustion engine control device according to claim 1, wherein the valve adjusting means adjusts the opening / closing timing in accordance with a rotational speed and a load factor of the internal combustion engine.   The correction amount determination means includes an intake valve control amount that represents a difference between the phase of the opening / closing timing of the intake valve and a reference angle, and an exhaust valve control amount that represents a difference between the phase of the opening / closing timing of the exhaust valve and a reference angle; The internal combustion engine control apparatus according to any one of claims 1 to 6, wherein a correction amount of the target air-fuel ratio is determined using at least one of the opening / closing timing as the opening / closing timing.   8. The internal combustion engine control device according to claim 7, wherein the correction amount determining means sets the reference angle of the phase of the intake valve as the most retarded angle and sets the reference angle of the phase of the exhaust valve as the most advanced angle. . An oxygen concentration sensor for detecting an oxygen concentration in an exhaust pipe provided in the internal combustion engine;
The correction amount determining means compensates for a change in the output of the oxygen concentration sensor when the opening / closing timing is controlled with respect to an output of the oxygen concentration sensor when the opening / closing timing is not controlled. 9. The internal combustion engine control apparatus according to claim 1, wherein a correction amount of the air-fuel ratio is determined.

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