JP2008303777A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively satisfy two different demands when controlling the engine speed or engine torque to a desired value in an internal combustion engine. <P>SOLUTION: When controlling the engine speed or engine torque to a desired value, in a part of cylinders, a first control amount is fixed so as to satisfy a first demand (Step 101) and a second control amount is feedback controlled (Steps 103, 104). In other cylinders, the second control amount is fixed so as to satisfy a second demand (Step 102), and the first control amount is feedback controlled (Steps 105, 106). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

  In order to stabilize the combustion of an internal combustion engine, it has been proposed to simultaneously control the state of an air-fuel mixture such as an air-fuel ratio and the ignition timing in the same cylinder (see, for example, Patent Document 1). In combustion stabilized by such control, two different requirements of a low fuel consumption air-fuel ratio and an ignition timing at which high torque in the vicinity of MBT (Minimum Spark Advance for Best Torque) is obtained can be satisfied simultaneously. preferable. However, because the two controls interfere with each other and warp, the combustion may become unstable, so the air-fuel ratio correction amount is calculated based on combustion fluctuations in a specific frequency band, and the ignition timing correction amount is calculated. By correcting the ignition timing correction amount by reducing the signal level of the same specific frequency band with respect to the engine state signal to be used, interference between the two controls is prevented.

JP-A-8-135483 JP 2000-310144 A JP 2004-3397 A

  The above-mentioned specific frequency band is, for example, a preset drive system resonance frequency band of the vehicle, but may change with time, and at this time, although combustion can be stabilized, It becomes impossible to realize both of the two different requirements of the air-fuel ratio of fuel consumption and the ignition timing in the vicinity of MBT.

  Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that can reliably satisfy two other different requirements when controlling the engine speed or engine torque to a desired value in the internal combustion engine. It is.

  The control apparatus for an internal combustion engine according to claim 1 of the present invention is a control apparatus for a multi-cylinder internal combustion engine, and when the engine speed or the engine torque is controlled to a desired value, the first requirement is applied to some cylinders. The first control amount is fixed so that the first control amount is satisfied, and the second control amount is feedback-controlled. In the other cylinders, the second control amount is fixed so that the second requirement is satisfied, and the first control amount is The quantity is feedback controlled.

  According to a second aspect of the present invention, there is provided the control apparatus for an internal combustion engine according to the first aspect, wherein the partial cylinder is controlled after the engine speed or the engine torque is controlled to the desired value. A combination of the first control amount fixed in the second cylinder and the second control amount feedback-controlled in the partial cylinder is used in all the cylinders, or the second control fixed in the other cylinders. A combination of the amount and the first control amount feedback controlled in the other cylinder is used in all the cylinders, and the engine speed or the engine torque is controlled to the desired value.

  An internal combustion engine control apparatus according to a third aspect of the present invention is the internal combustion engine control apparatus according to the first aspect, wherein after the engine speed or the engine torque is controlled to the desired value, The engine speed or the engine torque is controlled to the desired value by replacing the other cylinder.

  According to a fourth aspect of the present invention, there is provided the control device for an internal combustion engine according to any one of the first to third aspects, wherein the desired value is an idle speed immediately after the engine is started. The first control amount is a fuel amount, the second control amount is an ignition timing, and the heavier the fuel supplied into the cylinder, the larger the number of the other cylinders. .

  According to the control apparatus for an internal combustion engine according to claim 1 of the present invention, when the engine speed or the engine torque is controlled to a desired value when the engine speed or the engine torque is controlled to a desired value, The first control amount is fixed so that one request is satisfied, and the second control amount is feedback-controlled. In the other cylinders, the second control amount is fixed so that the second request is satisfied. In order to feedback control the amount, the first requirement is reliably satisfied in some cylinders, and the second requirement is reliably satisfied in other cylinders.

  According to the control apparatus for an internal combustion engine according to claim 2 of the present invention, in the control apparatus for the internal combustion engine according to claim 1, the first request is made after the engine speed or the engine torque is controlled to a desired value. Alternatively, in order to satisfy either of the second requirements in all cylinders, a combination of the first control amount fixed in some cylinders and the second control amount feedback-controlled in some cylinders is used in all cylinders. Alternatively, a combination of the second control amount fixed in the other cylinder and the first control amount feedback-controlled in the other cylinder is used in all the cylinders, and the engine speed or the engine torque is controlled to the desired value. Is done.

  According to the control apparatus for an internal combustion engine according to claim 3 of the present invention, in the control apparatus for the internal combustion engine according to claim 1, after the engine speed or the engine torque is controlled to a desired value, By replacing the other cylinders and controlling the engine speed or engine torque to a desired value, feedback control of both the first control amount and the second control amount is performed in some cylinders and other cylinders. In some cylinders and other cylinders, the feedback gains of both the first control amount and the second control amount can be learned and corrected.

  According to the control apparatus for an internal combustion engine according to claim 4 of the present invention, in the control apparatus for the internal combustion engine according to any one of claims 1 to 3, the desired value is an idle speed immediately after the engine is started. The first control amount is the fuel amount, the second control amount is the ignition timing, and the heavier the fuel supplied into the cylinder, the greater the number of other cylinders that feedback control the fuel amount. It has become. When the engine temperature is low when the engine is started, the heavy fuel is difficult to vaporize, and in some cylinders where the fuel amount is fixed, the ignition timing may be excessively advanced. Thereby, the number of other cylinders is increased, and the number of partial cylinders whose ignition timing is excessively advanced is reduced.

  A control device (electronic control device) according to the present invention is for controlling the engine speed or engine torque of a multi-cylinder internal combustion engine to a desired value. At this time, it is preferable to reduce the unburned fuel in the exhaust gas to minimize fuel consumption, and to realize good combustion with the ignition timing in the vicinity of MBT. It is desirable to realize both the first requirement for realizing such low fuel consumption and the second requirement for realizing good combustion.

  FIG. 1 is a flow chart implemented by the control device according to the invention for satisfying two different requirements. This flowchart is for controlling, for example, an idle speed immediately after engine start to a desired value in a four-cylinder internal combustion engine, for example, as a multi-cylinder internal combustion engine. The ignition order of the four-cylinder internal combustion engine is, for example, in the order of # 1 cylinder, # 3 cylinder, # 4 cylinder, and # 2 cylinder.

  First, in step 101, the cylinders # 1 and # 4, which are preferably in non-sequential ignition sequence, are partly cylinders, and for these cylinders, an air-fuel ratio with low fuel consumption is realized with respect to the current intake air amount. The fuel amount F (first control amount) supplied to the cylinder is fixed. Next, in step 102, the # 2 cylinder and the # 3 cylinder are set as the other cylinders, and the ignition timing (second control amount) is fixed to MBT (A) in the current operation state for these cylinders.

  Next, at step 103, the engine speed N1 immediately after the compression top dead center TDC of some cylinders, for example, the # 1 cylinder (for example, after 45 crank angles), that is, the engine speed N1 affected by the combustion of the # 1 cylinder (constant) Since it is not a value, it is determined whether or not (for example, an intermediate value) substantially matches the desired value N. Initially, this determination is denied, and in step 104, the ignition timings (second control amounts) of the # 1 and # 4 cylinders, which are some cylinders, are determined according to the deviation ΔN1 between the engine speed N1 and the desired value N. Feedback control. Specifically, when the deviation ΔN1 is a positive value, the ignition timing is retarded, and when the deviation ΔN1 is a negative value, the ignition timing is advanced. The amount of retardation or advance of one time may be a constant value, but may be increased as the absolute value of the deviation ΔN1 is larger.

  Next, at step 105, the engine speed N2 immediately after the compression top dead center TDC of the other cylinder, for example, the # 2 cylinder (for example, after 45 crank angles), that is, the engine speed N2 (a constant value) that is affected by the combustion of the # 2 cylinder. Therefore, it is determined whether or not the intermediate value is substantially equal to the desired value N, for example. Initially, this determination is denied, and in step 106, the fuel amounts (first control amounts) of the # 2 and # 3 cylinders, which are the other cylinders, are fed back in accordance with the deviation ΔN2 between the engine speed N2 and the desired value N. Control. Specifically, when the deviation ΔN2 is a positive value, the fuel amount is decreased, and when the deviation ΔN2 is a negative value, the fuel amount is increased. Further, the amount of decrease or increase in one time may be a constant value, but may be increased as the absolute value of the deviation ΔN2 increases.

  If such processing is repeated, the engine speed can be made substantially coincident with the desired value N, and the control amount of each cylinder at this time is as shown by control 1 in FIG. That is, in some cylinders # 1 and # 4, the fuel amount that is the first control amount is fixed to the fuel amount F that realizes a low fuel consumption air-fuel ratio, and the ignition timing that is the second control amount. Is feedback controlled to A ′. Further, in the other cylinders # 2 and # 3, the ignition timing that is the second control amount is MBT (A) in which high torque is realized, and the fuel amount that is the first control amount is F ′. Is feedback controlled.

  In this way, low fuel consumption, which is the first requirement, can be reliably realized in some cylinders, and high torque, which is the second requirement, can be realized in other cylinders. When the engine speed is maintained at the desired value N after the engine speed is controlled to the desired value, or when the engine speed is set to the desired value N after a while, either the first request or the second request In order to satisfy all the cylinders, the first control amount (fuel amount F) fixed in some cylinders (# 1 cylinder and # 4 cylinder) and the second control amount (feedback control in some cylinders) ( The combination with the ignition timing A ′) is used in all the cylinders, or the second control amount (ignition timing A) fixed in the other cylinders (# 2 cylinder and # 3 cylinder) and the feedback control in the other cylinders A combination with the first control amount (fuel amount F ′) may be used in all cylinders.

  By the way, in some cylinders (# 1 cylinder and # 4 cylinder), when the ignition timing A ′ subjected to feedback control deviates by a% from the MBT (A), the larger the deviation is, The feedback gain of the ignition timing feedback control can be greatly learned and corrected. Also. In the other cylinders (# 2 cylinder and # 3 cylinder), when the fuel amount F ′ subjected to feedback control deviates by b% from the fuel amount F realizing the desired air-fuel ratio, the degree of this divergence is large. Thus, the feedback gain of the fuel amount feedback control can be greatly learned and corrected.

  However, in this state, the feedback gain of the fuel amount feedback control cannot be learned and corrected in some cylinders, and the feedback gain of the ignition timing feedback control cannot be learned and corrected in other cylinders. Thereby, after the engine speed is controlled to a desired value, some cylinders and other cylinders are exchanged. In some cylinders, the ignition timing as the second control amount is fixed to MBT (A), The amount of fuel that is the first control amount is feedback controlled, and in the other cylinders, the amount of fuel that is the first control amount is fixed to the fuel amount F that realizes a low fuel consumption air-fuel ratio, and is the second control amount. The ignition timing may be feedback controlled.

  Thereby, as shown in control 1 and control 2 in FIG. 2, feedback control of the first control amount (fuel amount) and the second control amount (ignition timing) is performed in some cylinders and other cylinders. In the cylinder and the other cylinders, the feedback gain can be learned and corrected based on the degree of divergence between the first control amount and the second control amount subjected to feedback control. Of course, the degree of deviation used for learning correction is not limited to the plus or minus percentage display, but may be a deviation display including plus or minus.

  Strictly speaking, the generated torque differs between some cylinders and other cylinders because the amount of feedback control is different. Thereby, in the present embodiment, the combustion is alternately performed in some cylinders and other cylinders, and torque fluctuation is suppressed. However, the number of partial cylinders and the number of other cylinders are not necessarily the same.

  For example, as shown not only in the pattern P2 of FIG. 3 described above but also in the pattern P1 of FIG. 3, some cylinders for feedback control of the second control amount (ignition timing) are the # 1 cylinder, the # 2 cylinder, and The # 3 cylinder may be used, and the other cylinder that feedback controls the first control amount (fuel amount) may be the # 4 cylinder. Further, as shown in pattern P3, a part cylinder for feedback control of the second control amount (ignition timing) is set to # 4, and another cylinder for feedback control of the first control amount (fuel amount) is set to # 1 cylinder, # 2 Cylinders and # 3 cylinders may be used.

  When the engine speed is controlled to the desired value N immediately after starting the engine, the heavy fuel is difficult to vaporize because the engine temperature is low, and the ignition timing is excessive in some cylinders where the fuel amount is fixed at this time. May be advanced. Accordingly, it is preferable that the heavier the fuel supplied into the cylinder, the larger the number of other cylinders that feedback control the fuel amount, and the smaller the number of cylinders whose ignition timing is excessively advanced.

  In the present embodiment, the first control amount is the fuel amount and the second control amount is the ignition timing, but this combination does not limit the present invention. For example, the first control amount may be the air-fuel ratio of the air-fuel mixture itself, the intake air amount or EGR amount that affects the air-fuel ratio of the air-fuel mixture, or the fuel injection timing. Further, in the V-type engine, it is preferable that one bank is a partial cylinder and the other bank is another cylinder. In the present embodiment, the case where the idling speed immediately after the engine start is controlled to the desired value N has been described. However, this does not limit the present invention, and the engine speed or the engine torque is not limited to just after the engine start. The present invention can be applied when controlled to a desired value.

2 is a flow chart implemented by a control device according to the present invention to satisfy two different requirements. It is a table | surface which shows the control result of the flowchart of FIG. It is a table | surface which shows the combination pattern of a part cylinder and another cylinder.

Claims (4)

  A control device for a multi-cylinder internal combustion engine, wherein when the engine speed or engine torque is controlled to a desired value, the first control amount is fixed to a second value so that the first requirement is satisfied in some cylinders. A control apparatus for an internal combustion engine, wherein the control amount is feedback-controlled, and in the other cylinders, the second control amount is fixed and the first control amount is feedback-controlled so that the second requirement is satisfied.   After the engine speed or the engine torque is controlled to the desired value, a combination of the first control amount fixed in the partial cylinder and the second control amount feedback-controlled in the partial cylinder is obtained. A combination of the second control amount that is used in all cylinders or fixed in the other cylinders and the first control amount that is feedback controlled in the other cylinders is used in all cylinders, and the engine speed 2. The control device for an internal combustion engine according to claim 1, wherein the engine torque is controlled to the desired value.   2. The engine speed or engine torque is controlled to the desired value by exchanging the partial cylinder and the other cylinder after the engine speed or engine torque is controlled to the desired value. The control apparatus of the internal combustion engine described in 1.   The desired value is an idle speed immediately after the engine is started, the first control amount is a fuel amount, the second control amount is an ignition timing, and the fuel supplied into the cylinder is heavier. 4. The control device for an internal combustion engine according to claim 1, wherein the number of the other cylinders is increased.

Images