JP2011047326A - Control device for exhaust passage switching type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform correction according to a change in an exhaust state by gradually changing ignition timing when switching an exhaust passage, and to improve torque fluctuations by improving ignition timing control performance according to an in-cylinder air-fuel mixture. <P>SOLUTION: The ignition timing from the starting of the switching of an exhaust passage selector valve to the completion of the switching thereof is calculated based on the following results: a reference ignition timing calculation result in closing the exhaust passage selector valve, calculating the ignition timing when the exhaust passage selector valve is opened by an exhaust passage selector valve driving means; a reference ignition timing calculation result in closing the exhaust passage selector valve, calculating the ignition timing when the exhaust passage selector valve is closed by the exhaust passage selector valve driving means; a determination result for a condition for switching the exhaust passage selector valve, switching the exhaust passage selector valve based on the operating condition of an internal combustion engine; a calculation result with the actual operating state of the exhaust passage selector valve detected or estimated; and a calculation result for an ignition timing damper correction coefficient, calculating a variation in the ignition timing when switching the exhaust passage selector valve and calculating the amount of ignition timing damper correction from the starting of the switching of the exhaust passage selector valve to the completion of the switching thereof. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ignition timing control apparatus for an internal combustion engine, and more particularly to an internal combustion engine control apparatus that optimally corrects an ignition timing in a control system that switches a plurality of exhaust passages.

  In order to improve the exhaust performance of an internal combustion engine, the catalyst provided in the exhaust pipe is activated early. As a method for this, a plurality of exhaust passages of the exhaust pipe are switched to selectively use a plurality of catalysts provided for each exhaust passage. The purpose of switching the exhaust passage and selectively using a plurality of catalysts is to use an early activation catalyst having a small capacity and good thermal conductivity in addition to the conventionally used catalyst to shorten the time for which the catalyst is activated. For example, in the technique described in Patent Document 1, the exhaust passage is switched to use the early activation catalyst until the catalyst is activated. At this time, in order to raise the catalyst temperature early, the ignition timing is changed to the retard side to raise the exhaust gas temperature.

JP-A-5-321643

  However, when the ignition timing of the internal combustion engine cannot cope with the change in the exhaust pressure due to the switching of the exhaust passage, the operability may be deteriorated due to an increase in torque fluctuation.

  The present invention has been made in order to solve the above-described problem. In order to cope with the in-cylinder mixture when the exhaust passage is switched, the ignition timing change is made smooth according to the change in the exhaust passage state, so that the torque is increased. An object of the present invention is to provide a control device for an internal combustion engine that improves fluctuations.

An internal combustion engine control apparatus according to the present invention includes an exhaust pipe of an internal combustion engine having a plurality of exhaust passages, an exhaust passage switching valve that switches the plurality of exhaust passages of the exhaust pipe, and a rotation that detects the rotational speed of the internal combustion engine. Number detection means, intake state detection means for detecting the intake state of the internal combustion engine, cooling water temperature detection means for detecting the temperature state of the internal combustion engine, and accelerator opening degree detection means for detecting the requested drive state of the internal combustion engine Load calculating means for calculating the load of the internal combustion engine from the detection value of the intake state detection means, and torque detection means for calculating the torque that becomes the driving amount of the internal combustion engine from the detection value of the accelerator opening detection means And an exhaust passage switching valve driving means for providing an electric drive signal for driving the exhaust passage switching valve,
Correcting the ignition timing from the start of switching of the exhaust passage switching valve to the completion of switching The ignition timing at the start of switching and at the completion of switching is based on the optimum value of the ignition timing at the opening / closing of the exhaust passage switching valve. Calculating the optimum value of the ignition timing when the exhaust passage switching valve is opened / closed based on at least one of the torque, the rotational speed, the load, and the coolant temperature From the start of switching of the exhaust passage switching valve The ignition timing damper correction coefficient calculating means for correcting the ignition timing until the completion of switching is calculated based on the detection or estimation of the actual operating state of the exhaust passage switching valve. The amount of change in the exhaust efficiency when the exhaust passage switching valve is switched is A control device for an internal combustion engine, characterized in that it is calculated based on a detected value or an estimated value of an exhaust passage area.

  The control apparatus for an internal combustion engine of the present invention configured as described above can correct the ignition timing in accordance with the exhaust state, which can contribute to the improvement of the stabilization of combustion and the stability of operability. it can.

  The control device for an internal combustion engine according to the present invention corrects the ignition timing from the start of switching to the completion of switching at the time of exhaust passage switching in a stepwise manner, and performs correction according to the change in the exhaust state to perform in-cylinder mixing. Since it is possible to improve the ignition timing control performance according to the ki, it is possible to stabilize combustion and contribute to improvement of drivability.

1 is an overall configuration diagram of an engine serving as an internal combustion engine of the present embodiment. The figure which shows the exhaust pressure at the time of the exhaust passage switching by the internal combustion engine control apparatus of FIG. The figure which shows the torque at the time of the ignition timing change by the internal combustion engine control apparatus of FIG. 1, fuel consumption, and surge torque. FIG. 3 is a control time chart of the present invention showing an exhaust passage switching valve drive command and an opening degree by the internal combustion engine control device of FIG. The figure which shows the relationship between the exhaust passage area by the internal combustion engine control apparatus of FIG. 1, an exhaust passage switching valve opening degree, an exhaust passage area, and exhaust efficiency. The figure which shows the correction method by the opening degree of the exhaust passage switching valve and ignition timing damper coefficient by the internal combustion engine control device of FIG. The control flowchart of this invention by the internal combustion engine control apparatus of FIG.

Hereinafter, an embodiment of an exhaust passage switching control device for an internal combustion engine according to the present invention will be described with reference to the drawings. FIG. 1 shows an outline of the entire system configuration for carrying out the present invention.
The engine 1 is a multi-cylinder engine including a plurality of cylinders 2 and pistons 3. The air sucked into each cylinder 2 is taken from the inlet of the air cleaner 30, passes through an air flow meter (air flow sensor 31), and enters a throttle body 33 containing an electrically controlled throttle valve (throttle 34) that controls the intake flow rate. And enters the collector 35. Here, the throttle 34 is operated by driving the throttle drive motor 37 based on the output signal of the accelerator opening sensor 39 in order to correspond to the depression amount of the accelerator pedal 38. The intake air amount can be controlled by drive control of the throttle drive motor 37. The intake air reaching the collector 35 is distributed to each intake pipe 36 connected to each cylinder 2 of the engine 1, and after the intake valve 11 is opened, it is guided to each cylinder 2. Here, a signal representing the intake flow rate is output from the air flow meter 31 to the engine control device (control unit 100). A throttle opening sensor 32 that detects the opening of the throttle 34 is attached to the throttle body 33, and the signal is also output to the control unit 100.

  On the other hand, fuel such as gasoline is injected into each intake pipe 36 from a fuel injection valve (injector 27). The intake air and the injected fuel mixed in each intake pipe 36 are ignited by the ignition plug 10 and burned by the ignition signal that has been increased in voltage by the ignition coil 9. Exhaust gas after combustion passes through the exhaust pipe 40 and is discharged from the engine 1. The exhaust pipe 40 is branched into two paths, and an exhaust passage switching valve 41 is provided on one of them. At this time, the control unit 100 outputs a drive signal to the exhaust passage switching valve drive motor 42 and drives the exhaust passage switching valve 41 to switch the exhaust passage. The opening degree of the exhaust passage switching valve 41 driven by the exhaust passage switching valve drive motor 42 is output to the control unit 100 by the exhaust passage switching valve opening degree sensor 43.

  When the exhaust passage switching valve 41 is in an open state, the amount of exhaust gas that passes through varies depending on the exhaust pressure of each of the branched exhaust pipes 40. On the other hand, when the exhaust passage switching valve 41 is in the closed state, the exhaust bypasses the exhaust passage provided with the exhaust passage switching valve 41, and an exhaust amount corresponding to the exhaust pressure of the other exhaust pipe passes. At this time, the A / F sensor 44 attached to the exhaust pipe 40 detects the air-fuel ratio from the exhaust and outputs a signal representing the air-fuel ratio to the control unit 100.

  A crank angle sensor 5 attached to the crankshaft 4 of the engine 1 detects the rotational position of the crankshaft 4 and outputs the angle signal to the control unit 100. The cam angle sensor 8 attached to the cam shaft 7 that drives the exhaust valve 12 detects the rotational position of the cam shaft 7 and outputs the angle signal to the control unit 100. The water temperature sensor 13 attached to the engine 1 detects the cooling water temperature of the engine 1 and outputs a detection signal to the control unit 100.

  FIG. 2 shows the exhaust pressure, the internal EGR amount, and the torque when the exhaust passage switching valve 41 is opened / closed. The upper stage shows the respective exhaust pressures when the exhaust passage switching valve 41 is opened / closed, and the opening area of the exhaust passage is reduced when the exhaust passage switching valve 41 is closed compared to when the exhaust passage switching valve 41 is opened. Exhaust efficiency decreases and exhaust pressure increases. The middle row shows the amount of internal EGR when the exhaust passage switching valve 41 is opened / closed. The internal EGR is that the exhaust gas is returned into the cylinder during the valve overlap of the intake valve 11 and the exhaust valve 12 of the internal combustion engine. When the exhaust passage switching valve 41 is closed, the exhaust pressure is compared with the open state. As the value increases, the amount of internal EGR increases. The lower row shows the respective torques when the exhaust passage switching valve 41 is opened / closed. When the exhaust passage switching valve 41 is closed, the amount of fresh air flowing into each cylinder 2 is reduced as the internal EGR amount is increased as compared to when the exhaust passage switching valve 41 is opened. The torque fluctuation is a factor that deteriorates drivability, so it needs to be reduced.

  FIG. 3 shows the relationship among torque, fuel efficiency, and drivability (surge torque in the figure) for each ignition timing when the exhaust passage switching valve 41 is opened / closed. Line A in the figure indicates when the exhaust passage switching valve 41 is opened, and line B indicates when the exhaust passage switching valve 41 is closed. The upper part shows the relationship between ignition timing and torque. When the exhaust passage switching valve 41 is opened / closed, MBT (here, MBT is the best point of output or fuel consumption at the ignition timing at which the maximum torque can be obtained, but is a known matter and will not be described in detail) ) Exists. Since the MBT also changes depending on the combustion speed in the cylinder, there is an MBT when the exhaust passage switching valve 41 is opened / closed, and the maximum torque amount is also different. This is done by decreasing the oxygen concentration of the in-cylinder mixture and decreasing the flame propagation speed as the internal EGR amount increases. When the ignition timing is advanced from MBT, useless compression work before compression top dead center increases, and torque decreases due to increase in mechanical loss and cooling loss. On the other hand, when the ignition timing is retarded, the expansion work to the piston is reduced, so the torque is reduced. The middle row shows the relationship between ignition timing and fuel consumption. The fuel consumption is also deteriorated by advancing or retarding the MBT, which is the best point, like the torque. The lower row shows the relationship between the ignition timing and surge torque (where the surge torque represents a variation in the combustion state and becomes smaller as the combustion stability is higher). The surge torque can be improved by optimizing the combustion speed. When the ignition timing is retarded, the combustion torque decreases and the surge torque deteriorates. In addition, advancement of the ignition timing increases the combustion speed, but induces knocking and deteriorates the surge torque. Accordingly, since the MBT changes due to the opening and closing of the exhaust passage switching valve 41, the present invention calculates the respective MBT when the exhaust passage switching valve 41 is opened / closed and switches the ignition timing.

  FIG. 4 shows a drive signal from the control unit 100 to the exhaust passage switching valve 41, an opening degree when the exhaust passage switching valve 41 is opened / closed, and an ignition timing damper correction coefficient (here, an ignition timing damper correction coefficient). Is a time chart showing the torque and the torque for changing the ignition timing in stages. The exhaust passage switching valve 41 calculates the ignition timing after switching when the drive permission is determined. However, when the exhaust passage switching valve 41 is opened / closed, the operation delay time (here, the operation delay time is the time from when the drive signal of the exhaust passage switching valve 41 is transmitted from the control unit 100 to when the operation is actually started). In addition, there is a first-order lag time from the start of operation to the end of operation. For this reason, torque fluctuation occurs when an ignition timing is set that does not accompany changes in exhaust pressure due to actual operation of the exhaust passage switching valve. Therefore, the ignition timing is also corrected using the ignition timing change rate according to the time from the start to the end of the operation when the exhaust passage switching valve 41 is opened / closed. Line A in the figure shows the case without ignition timing damper correction, and the ignition timing deviates from the required value immediately after the drive command of the exhaust passage switching valve 41, so that torque fluctuation occurs and the drivability deteriorates. . On the other hand, a line B in the figure shows a case where there is an ignition timing damper correction. Since the ignition timing can follow the actual operation of the exhaust passage switching valve 41, torque fluctuation can be suppressed.

  FIG. 5 shows the relationship between the exhaust passage area, the exhaust passage switching valve opening, the exhaust passage area, and the exhaust efficiency. Since the flow rate of the fluid can be expressed as exhaust passage area × density × flow velocity, the exhaust passage area and the exhaust efficiency can be expressed in a proportional relationship. Since the exhaust passage switching valve opening is detected here, the exhaust efficiency is calculated from the relationship between the exhaust passage switching valve opening and the exhaust passage area.

  FIG. 6 shows a correction method based on the opening degree of the exhaust passage switching valve 41 and the ignition timing damper coefficient. The line A in the figure is obtained by correcting the ignition timing according to the primary delay time of the exhaust passage switching valve 41 with the ignition timing change rate shown in FIG. Line B is obtained by dividing and correcting the difference in ignition timing into a predetermined number (in the figure, 5 divisions). Line C detects the exhaust passage switching valve opening and corrects it according to the nonlinear relationship between the exhaust passage switching valve opening and the exhaust efficiency shown in FIG. As described above, the ignition timing correction can be calculated based on the division based on the time and the difference and the exhaust passage switching valve opening.

  FIG. 7 is a flowchart for driving the exhaust passage switching valve 41. In the basic ignition timing calculation block 200 when the exhaust passage switching valve is opened, the operating state of the engine 1 is output to the control unit 100 by the crank angle sensor 5, the air flow meter 31, the water temperature sensor 13, and the accelerator opening sensor 39 when the engine 1 is driven. To do. As a result, the ignition timing is calculated with reference to the trimming map at the time of opening the exhaust passage switching valve in which the ignition timing is matched in advance with MBT. Then, an exhaust passage switching valve switching condition determination block 201 determines a request for opening / closing the exhaust passage switching valve 41. Here, since the present determination condition is not directly related to the present invention, the details are omitted. If it is determined by the exhaust passage switching valve switching condition determination block 201 that there is a request for closing the exhaust passage switching valve, the crank angle sensor 5, the air flow meter 31, and the water temperature sensor are calculated by the exhaust passage switching valve closing basic ignition timing calculation block 202. 13. As a result of outputting the operating state of the engine 1 to the control unit 100 by the accelerator opening sensor 39, the ignition timing is calculated with reference to MBT and a trimming map at the time of closing the exhaust passage switching valve adapted to the ignition timing in advance. Next, the operation delay time of the exhaust passage switching valve is calculated in advance by the valve operation delay time calculation block 203 when the exhaust passage switching valve is closed, and the ignition timing is changed after the operation delay time. Here, the means for detecting the state of the exhaust passage switching valve 41 is not limited to the operation delay time, but the operation delay can be determined from the actual operation state of the exhaust passage switching valve 41 using the exhaust passage switching valve opening sensor 43. . Next, an ignition timing damper correction coefficient is calculated by an exhaust passage switching valve closing time fire timing damper correction coefficient calculation block 204. The exhaust passage changeover valve closing point fire timing damper correction coefficient is a value that can take a range of 0 to 1, and adds a weight that refers to the basic ignition timing when the exhaust passage changeover valve is closed or the basic ignition timing when it is opened. is there. Here, the degree of change in the ignition timing damper coefficient can be determined by the method shown in FIG. Then, the exhaust passage switching valve closing determination block 205 determines the operating state of the exhaust passage switching valve 41. As a result, after it is determined that the valve is not closed, the ignition timing correction block 206 corrects the ignition timing until the exhaust passage switching valve closing timing fire timing damper correction coefficient = 1. On the other hand, when the exhaust passage switching valve switching condition determination block 201 determines that there is a request for opening the exhaust passage switching valve, the exhaust passage switching valve operation delay time calculation block 207 calculates the operation delay time of the exhaust passage switching valve. Calculate in advance and change the ignition timing after the operation delay time. Next, an ignition timing damper correction coefficient is calculated by an exhaust passage switching valve opening time fire timing damper correction coefficient calculation block 208. Then, the exhaust passage switching valve opening determination block 209 determines the operating state of the exhaust passage switching valve 41. As a result, after it is determined that the valve is not opened, the ignition timing is corrected by the ignition timing correction block 206 until the exhaust passage switching valve opening timing fire timing damper correction coefficient = 0. By repeating both of these, it is possible to correct the ignition timing associated with the exhaust passage switching valve drive state.

1 Engine 2 Cylinder 3 Piston 4 Crankshaft 5 Crank Angle Sensor 7 Cam Shaft 8 Cam Angle Sensor 9 Ignition Coil 10 Spark Plug 11 Intake Valve 12 Exhaust Valve 13 Water Temperature Sensor 27 Injector 30 Air Cleaner 31 Airflow Sensor 32 Throttle Opening Sensor 33 Throttle Body 34 throttle 35 collector 36 intake pipe 37 throttle drive motor 38 accelerator pedal 39 accelerator opening sensor 40 exhaust pipe 41 exhaust passage switching valve 42 exhaust passage switching valve drive motor 43 exhaust passage switching valve opening sensor 44 A / F sensor 100 control unit

Claims (5)

An exhaust pipe having a plurality of exhaust passages;
An exhaust passage switching valve for switching a plurality of exhaust passages of the exhaust pipe;
In a control device for an internal combustion engine having
A rotational speed detection means for detecting the rotational speed of the internal combustion engine;
Intake state detection means for detecting the intake state of the internal combustion engine;
A coolant temperature detecting means for detecting a temperature state of the internal combustion engine;
An accelerator opening detecting means for detecting a required drive state of the internal combustion engine;
Load calculating means for calculating the load of the internal combustion engine from the detection value of the intake air condition detecting means;
Torque detecting means for calculating a torque to be a driving amount of the internal combustion engine from a detection value of the accelerator opening detecting means;
An exhaust passage switching valve driving means for providing an electric drive signal for driving the exhaust passage switching valve;
A control apparatus for an internal combustion engine, wherein an ignition timing from the start of switching of the exhaust passage switching valve to the completion of switching is corrected.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the ignition timing at the start of switching and at the completion of switching is calculated based on optimum values of the respective ignition timings when the exhaust passage switching valve is opened / closed. A control device for an internal combustion engine.   3. The control device for an internal combustion engine according to claim 1, wherein the optimum value of the ignition timing when the exhaust passage switching valve is opened / closed is based on at least one of the torque, the rotational speed, the load, and the coolant temperature. A control device for an internal combustion engine, characterized in that it calculates.   4. The control apparatus for an internal combustion engine according to claim 1, wherein an ignition timing damper correction coefficient calculating means for correcting an ignition timing from the start of switching of the exhaust passage switching valve to the completion of switching is an actual operating state of the exhaust passage switching valve. A control apparatus for an internal combustion engine, characterized in that calculation is performed based on detection or estimation of the engine.   5. The control apparatus for an internal combustion engine according to claim 1, wherein the amount of change in exhaust efficiency when the exhaust passage switching valve is switched is calculated based on a detected value or an estimated value of the exhaust passage area. Control device.

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