JP3960198B2 - 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, and more specifically, predicts a future throttle valve opening after a predetermined time has elapsed by delaying the start of driving of the engine throttle valve to a target opening, and based on this predicted value The present invention relates to a control device for an internal combustion engine that accurately predicts a future engine intake air amount.
[0002]
[Prior art]
There is a so-called electronically controlled throttle valve that can control the opening degree independently of the driver's accelerator pedal operation amount, and delays when controlling the throttle valve opening to the target throttle valve opening amount determined from the accelerator pedal operation amount 2. Description of the Related Art A control device for an internal combustion engine that accurately predicts an engine intake air amount by providing time is known.
[0003]
In general, an internal combustion engine measures the engine intake air amount, calculates the fuel injection amount based on the actually measured value, and controls so that the engine air-fuel ratio becomes an optimum value. It has been adopted. In these engines, it is important to accurately detect the engine intake air amount. However, when the engine intake air amount changes with changes in the throttle valve opening and rotation speed during transient operation, etc. It may be difficult to accurately measure the amount of air.
[0004]
In addition, since the amount of air actually taken into the cylinders of the engine is determined when the intake valve of each cylinder is closed, in order to accurately set the fuel injection amount, the amount of engine intake air when the cylinder intake valve is closed is used. It is necessary to set the fuel injection amount based on this. However, the timing for calculating the fuel injection amount of each cylinder is generally earlier than when the intake valve is closed. Therefore, in order to set an accurate fuel injection amount based on the air amount actually sucked into the cylinder, it is necessary to accurately predict the engine intake air amount at the time when the intake valve is closed in the future when the fuel injection amount is calculated. There is.
[0005]
The engine intake air amount changes according to the throttle valve opening and the engine speed. In addition, since the change speed of the throttle valve opening is relatively faster than the change speed of the engine speed in transient operation, if the throttle valve opening when the intake valve is closed can be accurately predicted, the engine when the intake valve is closed The amount of intake air can be predicted.
In an engine equipped with an electronically controlled throttle valve that can operate independently of the driver's accelerator pedal operation, the throttle valve opening and closing drive is delayed for a predetermined time, so that the future throttle valve opening can be accurately determined. A so-called phase advance inverse calculation method has been proposed that predicts and accurately estimates the future engine intake air amount (engine intake air amount when the cylinder intake valve is closed) based on the predicted throttle valve opening.
[0006]
An example of a control device for an internal combustion engine that performs this kind of intake air amount prediction is disclosed in Patent Document 1, for example.
The apparatus of Patent Document 1 sets a target opening of an electronically controlled throttle valve based on the current accelerator pedal operation amount (depression amount), and then immediately drives the throttle valve to control the target opening without a constant amount. The drive of the throttle valve is started after the delay time has elapsed. In general, since electronically controlled throttle valves are delayed in control or mechanism, even when the target opening changes suddenly (for example, stepwise), the throttle valve opening until the target opening is actually reached. In this case, a delay time determined from the operating characteristics of the throttle valve is generated.
[0007]
Therefore, if the operating characteristics of the throttle valve are accurately grasped, for example, even when the target opening of the throttle valve changes stepwise, each time until the throttle valve actually reaches the target opening after that. It is possible to calculate the throttle valve opening at the time. That is, theoretically, when the target opening degree changes stepwise, it becomes possible to predict the throttle valve opening degree at each future time point based on the operating characteristics of the throttle valve.
[0008]
However, in actual driving, when the driver's accelerator pedal operation amount is large and the target opening continuously changes, the throttle valve opening at each future time based on the throttle valve operating characteristics at a certain time. However, the predicted value does not reflect the change in the target opening after the prediction time, and there is a problem that the accuracy of the predicted throttle valve opening is lowered.
[0009]
After the target opening is set, the device of Patent Document 1 starts the operation of actually driving the throttle valve in accordance with the target opening by delaying by a certain delay time (a short time that the driver does not experience the delay). By doing so, it is possible to reflect the change in the target opening completely in the predicted throttle valve opening.
[0010]
That is, in the device of Patent Document 1, the actual throttle valve operation is delayed by the delay time with respect to the change in the target opening, but conversely, the throttle valve actually starts to operate. At that time, it is possible to know completely how the target throttle valve opening changes thereafter. For this reason, the change in the target opening can be completely reflected in the predicted value of the throttle valve opening, and the actual change in the throttle valve opening can be accurately predicted. With the above-described method, the device of Patent Document 1 accurately predicts the throttle valve opening when the intake valve is closed at the time of calculating the fuel injection amount, and calculates the engine intake air amount when the intake valve is closed based on this prediction. is doing.
[0011]
[Patent Document 1]
JP-A-10-169469
[Patent Document 2]
JP 2002-201998 A
[0012]
[Problems to be solved by the invention]
In the apparatus of Patent Document 1, it is possible to accurately predict the future engine intake air amount by delaying the actual throttle valve opening change by a slight time with respect to the operation of the accelerator pedal. This delay time is a time that the driver can hardly experience and does not cause a problem in driving feeling.
[0013]
However, in a vehicle engine or the like, it may be necessary to reduce the engine output torque for emergency evacuation separately from the operation of the driver. For example, in a vehicle equipped with a TRC (traction control) device, a VSC (vehicle running stability) device, or the like, when the slip of the drive wheel exceeds a predetermined value, the engine output torque is reduced to suppress the slip. Is required. In this case, regardless of the depression amount of the accelerator pedal of the driver, a valve closing request signal is sent to the electronic throttle valve, and the throttle valve target opening is reduced to a value corresponding to the valve closing request signal.
[0014]
However, TRC control and VSC control require extremely high control responsiveness in terms of vehicle running stability, and even when there is an emergency valve closing request due to these controls, the drive of the throttle valve has not been delayed. Even with a slight delay time, there is a possibility that the vehicle running stability will be adversely affected due to a decrease in control responsiveness.
[0015]
Therefore, normally, when calculating the engine intake air amount by the phase advance inverse calculation method by the throttle valve drive delay, when the emergency valve closing request is made, the drive of the throttle valve is started immediately without providing a delay time. So that it is close to the required throttle valve opening.
However, once the delayed drive of the throttle valve is stopped, the phase advance inverse calculation method can no longer accurately predict the intake air amount when the intake valve is closed in the future. In addition, even if the emergency valve closing request by traction control etc. is completed and the throttle valve delay drive is started again, it takes some time for the prediction result by the phase advance inverse calculation method to converge to an accurate value. Become. For this reason, since the intake air amount cannot be predicted during that time and accurate fuel injection control cannot be performed, there is a problem that engine performance and exhaust properties are deteriorated.
[0016]
Moreover, when there is an emergency valve closing request that is truly necessary for control as described above, it can be said that the throttle valve delay drive may be stopped or unavoidable in order to maintain running stability. In addition, a false valve closing request that cannot be distinguished from the emergency valve closing request may occur.
For example, in an electronic throttle valve or the like, a rotary shaft of a throttle valve is driven by a stepper motor or the like to rotate a plate-like valve body attached to the rotary shaft. However, since the valve body of the throttle valve does not need to rotate beyond the fully open position (position where the plate-like valve body is parallel to the intake flow direction), the electronic throttle valve does not always rotate beyond the fully open position. Thus, a limit signal (close signal) is supplied.
[0017]
The fully opened position of the throttle valve is about 85 degrees as the rotation angle of the rotation shaft. In this case, the rotation angle is always within 85 degrees for the stepper motor that drives the electronic throttle valve. As described above, the opening restriction signal is supplied.
This closing signal is AD converted and supplied to the stepper motor. When it is determined that the number of steps of the motor is larger than a value corresponding to 85 degrees, the throttle valve is controlled so that the rotation angle is 85 degrees or less. The valve is closed. In this case as well, since the throttle valve is not closed by the driver's accelerator pedal operation, it cannot be distinguished from the emergency valve closing request, and the delay drive of the throttle valve is stopped.
[0018]
However, when the throttle valve is actually in the vicinity of the fully open position, the throttle valve opening actually does not exceed the fully open position due to, for example, an error due to the resolution of the control circuit. There are many cases in which a minute false valve closing request of about several degrees is generated. For this reason, when the throttle valve is in the fully open position, the delayed drive of the throttle valve is interrupted due to the generation of a false valve closing request, and the intake air amount cannot be predicted by the phase advance inverse calculation method. .
[0019]
An object of the present invention is to solve the above problems and to provide a control device for an internal combustion engine that can reduce the frequency at which the prediction of the intake air amount is interrupted due to a false emergency valve closing request near the throttle valve opening fully open. Yes.
[0020]
[Means for Solving the Problems]
According to the first aspect of the present invention, the target throttle valve opening of the internal combustion engine is set based on the current accelerator pedal operation amount, and the actual throttle valve opening is set to the target opening in advance. By starting the throttle valve after a predetermined delay time has elapsed, an actual throttle valve opening in the future after a predetermined time has elapsed from the present time is predicted, and after the predetermined time has elapsed based on the predicted throttle valve opening The engine intake air amount in the future is calculated. When the throttle valve target opening is set to a value smaller than the current value by a predetermined emergency valve closing request signal, the throttle valve opening is immediately set without providing the delay time. In the control device for an internal combustion engine that starts driving the throttle valve so that the target opening becomes the target opening, the target opening of the throttle valve corresponds to the change in the opening of the throttle valve. When the throttle valve target opening is set by the emergency valve closing request signal when the actual throttle valve opening area is in the throttle valve opening range where the change in the actual throttle valve opening is zero, Provided is a control device for an internal combustion engine, which starts driving a throttle valve so that an actual throttle valve opening becomes a target opening after the delay time has elapsed.
[0021]
That is, according to the first aspect of the present invention, the throttle valve target opening set by the emergency valve closing request signal is the throttle valve opening region where the change in the actual throttle valve opening area with respect to the change in the throttle valve opening is zero, that is, the throttle If the opening area of the throttle valve does not change even if the opening of the valve is slightly changed, the throttle valve is delayed and driven as usual even in the case of the valve closing operation due to the emergency valve closing request.
[0022]
In such a region, even if there is a change in the throttle valve opening, the throttle valve opening area does not change. Therefore, the engine output does not change regardless of whether or not the throttle valve is delayed. For this reason, even if an emergency valve closing request is truly required, problems such as response delay due to delay drive do not occur.
[0023]
According to the second aspect of the present invention, the throttle valve is a butterfly valve having a plate-like valve body that is rotated by a rotation shaft, and an actual throttle valve opening area with respect to a change in the opening of the throttle valve. 2. The control device for an internal combustion engine according to claim 1, wherein the throttle valve opening region in which the change of the valve is zero is a region where the plate-like valve body overlaps the rotating shaft when viewed from the intake flow direction. .
[0024]
That is, in the invention of claim 2, the region where the throttle valve continues to be delayed even when there is an emergency valve closing request signal is a region where the valve body of the throttle valve overlaps the throttle valve floor coaxially when viewed from the intake flow direction, The throttle valve is set to a region near the fully open throttle valve opening where the valve body is substantially parallel to the intake air flow.
[0025]
This throttle valve opening region is a relatively narrow region near the full opening of the throttle valve, and as described above, a false emergency valve closing request signal is likely to be output in this vicinity, and for all generated valve closing request signals, If the delay operation of the throttle valve is interrupted, accurate fuel injection control cannot be performed.
In addition, since the emergency valve closing request signal is output to reduce the engine output torque, the target throttle valve opening normally set by the emergency valve closing request signal is thus close to the throttle valve fully open. It is unlikely to be set in the area. For this reason, by continuing the delay drive of the throttle valve in the above region, it is possible to reduce the frequency at which the intake air amount prediction by the phase advance reverse calculation is interrupted due to a false valve closing request signal.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of an embodiment in which the present invention is applied to an automobile internal combustion engine.
[0027]
In FIG. 1, reference numeral 1 denotes an internal combustion engine body, 3 denotes an intake passage of the engine 1, and 5 denotes a throttle valve provided in the intake passage 3.
In this embodiment, the throttle valve 5 is a so-called electronic throttle valve that is driven by an actuator 5a such as a stepper motor and can set the opening degree independently of the driver's accelerator pedal operation.
[0028]
An electronic control unit (ECU) of the engine 1 is indicated by 30 in FIG. The ECU 30 is a microcomputer having a known configuration in which a ROM, a RAM, a CPU, an AD converter, and the like are connected by a bidirectional bus. The ECU 30 performs basic control such as fuel injection control and ignition timing control of the engine 1, and in this embodiment, when the throttle valve 5 is driven in accordance with the operation of the accelerator pedal (not shown) by the driver, Is delayed for a certain period of time to perform “prefetching” of the throttle valve opening, and based on this prefetched throttle valve opening, control is performed to predict the intake amount of the engine by a phase advance inverse calculation method.
[0029]
For these controls, the ECU 30 receives the rotational speed NE of the engine 1, the accelerator opening (a driver's accelerator pedal operation amount) AC, and the like from respective sensors (not shown). The ECU 30 is connected to a fuel injection valve and an ignition plug (not shown) of the engine 1 to control the fuel injection and ignition timing of the engine, and is connected to an actuator (stepper motor) 5a of the throttle valve 5. The throttle valve opening is controlled.
[0030]
Next, calculation of the fuel injection amount of the engine of this embodiment will be described.
In the present embodiment, the fuel injection amount (injection time of each fuel injection valve) TAU is calculated from the following equation based on the intake air amount and engine speed of each cylinder.
TAU = (KL / NE) × KINJ × α × FAF (1)
Here, KL represents the engine intake air amount (flow rate), and NE represents the engine speed. As will be described later, since the intake air amount of each cylinder is determined when the cylinder intake valve is closed, in this embodiment, KL uses the engine intake air amount when the cylinder intake valve is closed. Normally, the fuel injection amount calculation timing of each cylinder is earlier than the cylinder intake valve closing timing, and therefore the measured value of KL cannot be used when calculating TAU. For this reason, in the present embodiment, a pre-reading of the intake air amount, which will be described later, that is, a predicted intake amount when the cylinder intake valve is closed, which is obtained by a phase advance inverse calculation method, is used.
[0031]
KINJ is a conversion constant for calculating the amount of fuel for setting the engine air-fuel ratio to the target air-fuel ratio (for example, the theoretical air-fuel ratio), and α is a correction coefficient determined from the engine warm-up state and other operating states. , FAF is a correction coefficient for feedback control of the fuel injection amount so that the exhaust air-fuel ratio (that is, the combustion air-fuel ratio of the engine) detected by the air-fuel ratio sensor disposed in the engine exhaust passage becomes the target air-fuel ratio.
[0032]
Next, a method for calculating the cylinder intake air amount KL according to the present embodiment will be described.
The intake air amount of the cylinder is determined by the intake pipe pressure PM when the cylinder intake valve is closed and the cylinder charging efficiency KTP. Further, when the engine is operating in a steady state (that is, when the engine speed NE and the throttle valve opening TA are maintained constant), the intake pipe pressure PM and the charging efficiency KTP are determined by the throttle valve opening. It becomes a function of the degree TA and the engine speed NE, and is uniquely determined if the throttle valve opening degree TA and the engine speed NE are determined. Therefore, the cylinder intake air amount KL is also a function of the engine speed NE and the throttle valve opening TA, and the intake air amount KL when the intake valve is closed is equal to the engine speed NE when the intake valve is closed and the throttle valve opening. It can be calculated from the degree TA.
[0033]
In the present embodiment, the engine intake air amount KL is measured in each combination condition of the engine speed NE and the throttle valve opening TA during the steady engine operation using an actual engine in advance, and the value of this intake air amount KL is measured. Are stored in the ROM of the ECU 30 in the form of a map using TA and NE. During the engine operation, the ECU 30 calculates the engine intake air amount in the engine steady operation from this map using the throttle valve opening degree TA and the engine speed NE.
[0034]
As described above, the amount of air actually sucked into the cylinder is determined when the intake valve of the cylinder is closed. For this reason, in the present embodiment, the intake air amount when the intake valve is closed is predicted using the engine speed NE and the throttle valve opening TA at the fuel injection timing (while the intake valve is open), and based on this predicted value. Calculation operation of the fuel injection amount TAU is performed. In the following description, the predicted intake air amount when the intake valve is closed is referred to as KLFWD.
[0035]
Hereinafter, calculation of KLFWD will be described.
If the intake air amount in steady operation read from the map using TA and NE is KLTA, KLTA changes immediately if the throttle valve opening TA or the engine speed NE changes, but the actual intake air amount KL Even if TA and NE change, it does not immediately become the value KLTA after the change, but changes with a certain delay time.
[0036]
FIG. 2 is a diagram for explaining the actual change of the intake air amount KL when the map value KLTA of the intake air amount changes stepwise due to changes in TA, NE, and the like. As shown in FIG. 2, when KLTA changes stepwise, KL changes relatively slowly, and reaches the changed KLTA after a certain period of time. The behavior of KL can be approximated by a first-order lag response system with respect to changes in KLTA. Therefore, if the current intake air amount (calculated value) is KLCRT, the KLCRT can be calculated from the values of the past intake air amount and the current KLTA using a temporary delay response model.
[0037]
That is, KLCRT can be expressed using the following temporary delay response equation.
KLCRT = KLCRT _i-1 + (KLTA-KLCRT _i-1 ) / N (2)
Here, KLCRT is the current intake air amount (calculated value), KLCRTi-1 is the intake air amount before the time Δt, and KLTA is the intake air in a steady state determined from the current throttle valve opening TA and the engine speed NE. It is a quantity (map value).
[0038]
N is a weighting coefficient, and is expressed as N = T / Δt using the time constant T of the first-order lag response and the above Δt. The time constant T is a value determined by the throttle valve opening TA and the engine speed NE, and can be obtained as a function of TA and NE in advance by experiments using an actual engine.
In the present embodiment, the calculation of the above equation (2) is started using the initial value of KLCRT = KLTA at the time of starting the engine, and thereafter the calculation of the above equation (2) is repeated at every engine operating time Δt. The current intake air amount KLCRT is calculated as a result of the sequential calculation from the start. As apparent from the equation (2), when the engine steady operation (that is, operation with a constant KLTA) continues to some extent, the value of KLCRT coincides with KLTA.
[0039]
By the way, the KLCRT calculated by the above is the value of the current intake air amount. As described above, the intake air valve closing of each cylinder best reflects the air amount actually sucked into the cylinder. Therefore, in order to accurately calculate the intake air amount KL, it is preferable to calculate using the intake air amount when the intake valve is closed. On the other hand, since the current intake air amount KLCRT is calculated by approximating the response of the intake air amount with a first-order lag response system as shown in FIG. 2, it is the same if the KLTA is kept constant after the change. It is possible to predict the intake air amount at a time earlier than the present time (the time of KLCRT calculation) by further repeating the sequential calculation of equation (2) using the first-order lag response model. That is, after calculating KLCRT, if the calculation of equation (2) is performed once using the same KLTA value, the intake air amount after the lapse of Δt from the present is calculated, and the calculation of equation (2) can be repeated twice. For example, the intake air amount after the lapse of 2 × Δt is calculated. That is, if the time from the present (the time when KLCRT is calculated) until the intake valve of any cylinder is closed next is L, the calculated value of KLCRT is used as an initial value and the current KLTA is used to formula (2) By repeating this calculation L / Δt times, the intake air amount when one of the cylinders is closed next can be calculated.
[0040]
That is, the intake air amount KLFWD at the time of closing the intake valve of any cylinder does not change from the current value of the rotational speed NE and the throttle valve opening TA (that is, if the calculated air amount KLTA is constant). ) And can be predicted by performing the sequential calculation of equation (2) using the current NE and TA.
[0041]
By the way, the value of KLTA used in the above sequential calculation is a map value based on the current TA and NE. However, since the value of NE does not change greatly in a short time, the calculation is performed using the current rotational speed. However, the prediction accuracy does not decrease so much. However, the value of TA may change greatly in a short time during transient operation (during rapid acceleration or deceleration).
[0042]
For this reason, in order to improve the prediction accuracy of KLFWD, when calculating KLFWD from the current intake air amount KLCRT by the above-described sequential calculation, the intake valve is not determined based on the current value TA, but the calculated air amount KLTA. It is necessary to obtain KLTA based on the value of the throttle valve opening TA when the valve is closed (future throttle valve opening).
Therefore, in the present embodiment, the throttle valve opening degree TA when the intake valve is closed is accurately predicted by the phase advance inverse calculation method proposed in Japanese Patent Laid-Open No. 10-169469.
[0043]
In this embodiment, an electronically controlled throttle valve 5 that includes an independent actuator 5a and is not mechanically connected to an accelerator pedal is used. The ECU 30 reads the depression amount of the accelerator pedal from an accelerator opening sensor (not shown) arranged in the vicinity of the accelerator pedal at a fixed timing, determines the throttle valve target opening according to the accelerator pedal depression amount, An operation of controlling the throttle valve 5 opening to the target opening by driving the actuator 5a is performed. Further, in the present embodiment, the ECU 30 delays the output of the target opening calculated for a certain delay time D after setting the target opening TAG of the throttle valve based on the current accelerator opening, The throttle valve that outputs the target opening degree TAG is delayed and driven at 5a, and the actual movement of the throttle valve relative to the operation of the accelerator pedal is delayed by time D. .
[0044]
Hereinafter, the reason why the operation of the throttle valve is delayed by the time D will be described.
FIG. 3A shows the relationship between the throttle valve target opening TAG and the actual change in the throttle valve opening. The throttle valve target opening degree TAG is set so as to change substantially simultaneously with the accelerator opening change even when the accelerator pedal depression amount (accelerator opening degree) AC of the driver changes suddenly. However, the actual throttle valve opening varies with a certain characteristic delay with respect to the target opening TAG due to the operation delay or control delay of the actuator 5a.
[0045]
That is, even when the target opening degree TAG (or the accelerator opening degree AC) changes abruptly as shown by the solid line in FIG. 3A, the actual throttle valve opening degree TA does not change with respect to the change of the TAG as shown by the dotted line. The change can be approximated with a first order delay. Since the operating characteristic of the throttle valve is known, for example, as shown in FIG. ₀ Thus, when the target opening changes stepwise, the actual throttle valve opening after the lapse of time L from the present time can be accurately predicted by the first-order lag approximation similar to that shown in Expression (2). However, the change in the target opening degree TAG is not actually stepped, but at the time t ₀ After that, the target opening degree TAG continues to change. For this reason, time t ₀ If the throttle valve opening after the lapse of the time L is predicted based on the target opening TAG at, the change in the target opening TAG until the lapse of the time L is not reflected in the prediction at all, and the target opening TAG is particularly abrupt. In such a case, there is a problem that the accuracy of predicting the throttle valve opening is greatly reduced.
[0046]
Therefore, in the present embodiment, the throttle valve opening prediction accuracy is improved by intentionally delaying the operation of the throttle valve by the time D. FIG. 3B is a diagram showing a case where the operation of the throttle valve is delayed by time D with respect to FIG. The accelerator opening AC is now at time t _i When the change is started at the time t, the target opening degree TAG corresponding to the change in the accelerator opening degree AC is inputted to the actuator of the throttle valve, and the throttle valve starts operating at the time t. _i When time D has elapsed from time t (FIG. 3 (B) t ₀ )become. At this time t ₀ Now, at time t _i Thereafter time t ₀ The target opening degree TAG is already set and known. This means that time t ₀ , The time t ₀ To the future by time D (FIG. 3B, time t ₁ Until the change in the target opening TAG ₀ Will be known. For this reason, time t ₀ To time t ₁ The throttle valve opening until this time can be accurately predicted based on the operating characteristics of the throttle valve and the change in the target opening TAG.
[0047]
Therefore, the closing timing of a certain cylinder is ₀ In time D (ie, at time t in FIG. 3B) ₁ In the earlier case), the throttle valve opening at the cylinder closing timing can be predicted with almost perfect accuracy. Also, the cylinder closing timing is t ₁ If later, at time t ₁ As a starting point, it is possible to predict the throttle valve opening degree when the intake valve is closed with extremely high accuracy by performing the same sequential calculation as that used in the above-mentioned KLCRT.
[0048]
Since the delay time is set to a short time (for example, about 20 to 100 milliseconds) so that the driver does not experience the delay in operation of the throttle valve, a delay in the operation of the throttle valve causes a problem in driving. Absent.
In the present embodiment, the change in the throttle valve opening TA until the intake valve close of the next cylinder is accurately predicted as described above, and the intake air amount is calculated from the predicted value and the current rotational speed NE using a map. Find the value KLTA. Further, the intake air amount KLFWD at the time of closing of the intake valve is predicted by performing the sequential calculation of the above-described equation (2) until the cylinder is closed using the KLTA and KCRT.
[0049]
As described above, in the present embodiment, the throttle valve drive is delayed by the predetermined delay time D, so that the throttle valve target opening degree TAG at each time point until the previous time by D is always prefetched, and the sequential use of the TAG is performed. An intake air amount KLFWD when the intake valve is closed is obtained by calculation.
In this way, the engine intake air amount can be accurately calculated by delaying the drive of the throttle valve, and highly accurate fuel injection control can be performed. Further, as described above, the delay of the throttle valve opening change with respect to the operation of the accelerator pedal is such that it cannot be experienced by a normal driver, and does not deteriorate the driving feeling of the vehicle.
[0050]
However, since the delay drive of the throttle valve delays the actual change of the output torque in response to the output torque change request, there may be a problem if the throttle valve is always delayed.
For example, a torque change request (torque reduction request) that is not caused by a driver's accelerator pedal operation may occur while the vehicle is traveling. A typical torque reduction request generated regardless of the driver's accelerator pedal operation is a torque reduction request (deceleration request) due to the operation of the traction control device (TRC) and the travel stability control device (VSC). )
[0051]
TRC prevents the drive wheels from slipping due to excessive engine output torque when starting or accelerating the vehicle, and the throttle valve is closed by a predetermined amount to suppress drive wheel slip. An operation to suppress the engine output torque is performed.
The VSC is for ensuring running stability during turning of the vehicle. For example, when a side slip occurs on the front wheel or the rear wheel during turning of the vehicle, the vehicle travels by reducing the driving torque of the wheels. An operation that makes it possible to perform a turn as intended by the driver by correcting the direction is performed.
[0052]
Since these output torque reduction requests (throttle valve closing requests) due to the operation of the VSC and TRC correspond to emergency situations and require high responsiveness, such emergency valve closing operations are required. It is not permissible to delay the start of driving the throttle valve in response to the request.
Therefore, in this embodiment, when there is a request for closing the throttle valve by TRC or VSC that is not caused by the driver's accelerator pedal operation, the delay drive of the throttle valve is interrupted and the delay time is not provided immediately. The throttle valve is driven (closed).
[0053]
However, in the calculation operation of the fuel injection amount, if the delay driving of the throttle valve, that is, the prefetching of the throttle valve target opening TAG is interrupted even a little, the calculation using only the current throttle valve target opening TAG must be performed. As a result, the prediction accuracy of the intake air amount KLFWD decreases. For this reason, when prefetching (throttle valve delay drive) is interrupted, an error may occur in the calculation of the fuel injection amount, which may cause deterioration in engine performance and exhaust properties.
[0054]
Of course, even if the throttle valve delay drive is temporarily interrupted, if the delay drive is restarted, the calculation accuracy of KLFWD improves and converges to an accurate value while repeating the calculation. When the interruption occurs, the engine performance as a whole and deterioration of exhaust properties cannot be ignored.
In addition, as described above, when the throttle valve opening is in the vicinity of the fully open position, a slight false closing of the throttle rotation angle of several degrees is caused by an error caused by the resolution of the control circuit for the opening limit signal. There are relatively many cases where a request is made, and if the delayed drive of the throttle valve is interrupted each time, the engine performance is deteriorated or the exhaust properties are deteriorated.
[0055]
In order to prevent this, if there is a minute valve closing request in the vicinity of the throttle valve opening fully open, it can be considered that it is a false valve closing request and ignored. However, in actuality, a slight valve closing request may be generated by the operation of the VSC or TRC. If all valve closing requests are uniformly ignored, there is a possibility that the output torque control by the VSC or TRC may be hindered. There is.
[0056]
Therefore, in the present embodiment, while the influence on the output torque control of the VSC and TRC is minimized by the method described below, the engine performance is deteriorated and the exhaust property is deteriorated due to frequent interruption of the delay drive of the throttle valve. It is prevented from occurring.
FIG. 4 is an enlarged cross-sectional view of the throttle valve 5 of the present embodiment. In FIG. 4, reference numeral 55 denotes a throttle valve housing (throttle body), 51 denotes a rotary shaft (valve shaft) 51 and 53 driven by a stepper motor 5a, and 53 denotes a plate-like valve body attached to the rotary shaft 51. Is shown.
[0057]
In FIG. 4, when the valve body 53 is at the position indicated by the symbol I, the throttle valve is fully closed. Further, when the valve body 53 rotates in the clockwise direction in FIG. 4 from the fully closed position and the valve body 53 is at a position (position indicated by reference numeral II in FIG. 4) substantially parallel to the intake flow direction. It becomes. In this embodiment, the throttle valve angle is represented by a rotation angle from the fully closed position (I), and the throttle valve angle θ is about 85 degrees at the fully open position (II).
[0058]
As described above, the throttle valve opening is limited so as not to exceed the fully open position (about 85 degrees). For this reason, when the throttle valve is in the vicinity of the fully open position, a false small angle (for example, several degrees). There is a case where an emergency valve closing request is generated, and a problem arises if the delay drive of the throttle valve is interrupted every time this false valve closing request is generated.
On the other hand, when the valve body 53 of the throttle valve 5 is in the vicinity of the fully open position, there is a throttle valve opening region where the opening area of the throttle valve does not change even when the valve body rotates.
[0059]
For example, in the angle region indicated by α in FIG. 4 from the fully open position of the valve body 53, the valve body of the throttle valve overlaps the valve shaft 51 when viewed from the intake flow direction (the arrow A direction in FIG. 4). The throttle valve opening area does not change and the engine output torque does not change even if the valve body 53 moves in the valve closing direction.
Therefore, in the present embodiment, when an emergency valve closing request is made during the delay drive of the throttle valve, the valve closing request angle (target opening degree) falls within the angle region α (opening area insensitive region) in FIG. In this case, the valve closing operation is performed in response to the valve closing request, but the delay driving of the throttle valve is continued and the driving of the throttle valve is started after the delay time D has elapsed.
[0060]
That is, in this embodiment, when an emergency valve closing request occurs, the ECU 30 determines that the valve closing request angle is smaller than the full opening angle −α (FIG. 4) (α is a small angle of about 5 degrees, for example) Immediately after the delay drive of the throttle valve is interrupted, the drive of the throttle valve is started toward the valve closing request angle. However, if the valve closing request angle is larger than the full opening angle −α, that is, if the valve closing request angle enters the opening area insensitive region in FIG. 4, the delay drive of the throttle valve is continued as it is.
[0061]
In general, when a valve closing request by VSC control or TRC control is generated, the valve closing request angle is usually a very small angle (an angle at which the throttle valve opening becomes small), and valve closing by VSC control or TRC control is performed. Although the required angle hardly enters the above-mentioned opening area insensitive region, it is not impossible at all. If the throttle valve is not driven by ignoring the minute valve closing request uniformly, if the valve closing request is valid, the valve closing request is continuously generated by VSC control or TRC control. In this case, the rotation angle of the throttle valve may be increased by the valve closing request angle neglected last time, and the response of the output torque change may be deteriorated.
[0062]
On the other hand, in this embodiment, even when there is a minute valve closing request that falls within the opening area insensitive area, the delay valve continues to operate, but the throttle valve body has a valve closing required angle. Therefore, the valve closing request is justified, and even when a valve closing request is subsequently generated by VSC control or TRC control, the valve closing operation is performed from this position, and the control responsiveness is improved. There is no deterioration.
[0063]
Further, according to the present embodiment, the pre-reading of the throttle valve opening by the delay drive of the throttle valve is not interrupted with respect to the false valve closing request that occupies most of the valve closing requests at a minute angle. It is possible to suppress the deterioration of the engine performance and the deterioration of the exhaust properties due to.
[0064]
【The invention's effect】
According to the invention described in each claim, it is possible to suppress the frequency with which the prediction of the intake air amount is interrupted by a false emergency valve closing signal, and to suppress deterioration in engine performance and deterioration in exhaust properties. The effect of.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an embodiment when the present invention is applied to an automobile internal combustion engine.
FIG. 2 is a diagram illustrating an intake air amount prediction method according to the present embodiment.
FIG. 3 is a diagram illustrating an intake air amount prediction method according to the present embodiment.
FIG. 4 is a cross-sectional view showing an opening area insensitive region of the throttle valve of the present embodiment.
[Explanation of symbols]
1 ... Internal combustion engine body
3 ... Intake passage
5 ... Throttle valve
5a ... Actuator
30 ... Electronic control unit (ECU)
51 ... Valve shaft
53 ... Valve

Claims (2)

Based on the current accelerator pedal operation amount, the throttle valve target opening of the internal combustion engine is set, and the throttle valve is driven after a predetermined delay time so that the actual throttle valve opening becomes the target opening. By starting, the actual throttle valve opening in the future after a predetermined time has elapsed from the present time, and the engine intake air amount in the future after the predetermined time has been calculated based on the predicted throttle valve opening. When the throttle valve target opening is set to a value smaller than the current value by a predetermined emergency valve closing request signal, the throttle valve opening is immediately adjusted to the target opening without providing the delay time. In the control device for an internal combustion engine that starts driving,
When the throttle valve target opening is in the throttle valve opening region where the actual change in the throttle valve opening area with respect to the change in the throttle valve opening is zero, the target valve opening is determined by the emergency valve closing request signal. A control apparatus for an internal combustion engine, which starts driving a throttle valve so that an actual throttle valve opening reaches a target opening even after the predetermined delay time has elapsed even if set. The throttle valve is a butterfly valve having a plate-like valve body that is rotated by a rotation shaft. 2. The control device for an internal combustion engine according to claim 1, wherein the plate-like valve body is an area overlapping the rotation shaft as viewed from the intake flow direction.

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