JP2002349332A - Vehicular engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly reduce an acceleration vibration without increasing an NOx content. SOLUTION: A drive system resonant frequency is set correspondingly to a gear position, and the set resonant frequency component is extracted from among the signal of an intake air amount detected by an air flow meter 6. The extracted resonant frequency component is converted into the reduction amount of engine torque after phase adjustment (setting of a required torque reduction amount). When the required torque reduction amount is a first set value or less, the torque reduction is performed by the delay angle of ignition timing and when being a second set value or more, the reduction is conducted by fuel cut. Further, when the reduction amount is in a range between the first and second set values, the torque is increased in the timing of valley thereof generated next the mount of torque to be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a vehicle engine.

[0002]

2. Description of the Related Art In a vehicle, an unpleasant vibration is often generated from a drive system during acceleration when an engine load is increased. This unpleasant vibration is mainly caused by torsional vibration of the drive shaft in the drive system, and occurs when the engine torque increased with an increase in the engine load includes the resonance frequency component of the drive system. The resonance frequency differs for each gear position of the transmission.

[0003] In order to reduce unpleasant vibrations generated from the drive system, Japanese Patent Application Laid-Open No. Hei 8-232696 discloses a predetermined mode which includes a resonance frequency component set according to the gear position of the transmission. It is disclosed that during acceleration, that is, when the mode of increasing the engine load is a predetermined mode, the engine torque is reduced by reducing the supplied fuel amount.
It is also disclosed that the supply fuel amount is reduced by delaying by about one rotation of the engine from the detection timing of the acceleration in a predetermined mode (phase matching).

[0004]

However, as described in the above-mentioned publication, reducing engine torque for reducing vibration during acceleration by reducing the fuel supply amount, that is, by making the air-fuel ratio lean, requires fuel economy. This is preferable from the viewpoint of improvement.

[0005] However, as the air-fuel ratio becomes leaner, a predetermined air-fuel ratio range in which the amount of NOx in the exhaust gas becomes extremely large becomes a problem. That is, as the engine leans from the stoichiometric air-fuel ratio (λ = 1, air-fuel ratio = 14.7), the amount of reduction in engine torque gradually increases (the engine torque itself gradually decreases), but the amount of NOx increases. Becomes maximum near the air-fuel ratio 16, and the NOx amount gradually decreases as the air-fuel ratio becomes rich or lean from the air-fuel ratio 16 around. If the required torque reduction amount is to be realized only by making the air-fuel ratio lean, the air-fuel ratio around 16 where the NOx amount becomes extremely large must be used.
In this regard, some measure is desired.

Further, as a technique for reducing the engine torque with a good response, it is conceivable to retard the ignition timing or cut the fuel. However, the retardation of the ignition timing is suitable when the torque to be reduced is small, but cannot be used when the torque to be reduced is large. Conversely, the fuel cut is preferable when the torque is largely reduced, but cannot be used when the torque to be reduced is small. In any case, it is practically difficult to respond to a wide range of low and medium degrees where the torque to be reduced is neither small nor large by retarding the ignition timing or cutting the fuel. However, in this case, the problem of NOx increase occurs as described above.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle engine control device capable of suitably reducing acceleration vibration without increasing NOx. It is in.

[0008]

In order to achieve the above object, according to the present invention, basically, when the engine torque is reduced in order to reduce the acceleration vibration, that is, when the torque is reduced, the torque to be reduced is reduced. In a small range, the torque is reduced by using the retard of the ignition timing, and in a range in which the torque to be reduced is large, the torque is reduced by using the fuel cut. When the torque to be reduced is moderate, the torque is not reduced but responded by increasing the torque. That is, the torque reduction is for canceling the peak of the torque generated in the initial stage of the acceleration vibration, and the valley of the torque generated next to the peak of the torque is canceled by the increase in the torque. .

[0009] Specifically, the following solution is adopted. That is, as described in claim 1 of the claims, during acceleration, a torque reduction means for obtaining a required torque reduction amount necessary for reducing acceleration vibration and reducing engine torque by the required torque reduction amount is provided. In the control device for a vehicle engine provided, the torque reduction unit reduces the engine torque by retarding the ignition timing when the required torque reduction amount is smaller than or equal to the first set value. When the value is larger than a second set value set to a value larger than the first set value, the engine torque is set to be reduced by fuel cut, and the required torque reduction amount is set to the first set value and the second set value. When the magnitude between the torque valley value and the torque valley that occurs next to the timing of the peak of the torque to be reduced by the torque reduction unit in the acceleration vibration, In that time,
Torque increasing means for increasing the engine torque so as to reduce the torque valley is provided.

Thus, when the torque to be reduced is smaller than the first set value, the torque can be accurately reduced by retarding the ignition timing. When the torque to be reduced is larger than the second set value, it is possible to sufficiently reduce the torque by fuel cut. When the torque to be reduced is intermediate between the first set value and the second set value, the torque is increased so as to fill a portion of the acceleration vibration that becomes a valley of the torque. It will be sufficiently prevented or suppressed. Needless to say, the reduction of the acceleration vibration due to the increase in the torque is caused by the reduction in the torque caused by the lean air-fuel ratio.
The problem of x increase will not occur.

The required torque reduction amount is equal to the first set value and the second set value.
When the magnitude is smaller than the set value, the torque reducing means may retard the ignition timing to the maximum retard amount. As a result, the peak of the torque at the beginning of acceleration can be made as small as possible, and the valley of the torque generated next can also be made small, so that the acceleration vibration can be more effectively reduced as a whole. In this case, the torque increasing means can increase the torque by a torque corresponding to a difference between the torque reduction amount obtained by the maximum retardation of the ignition timing by the torque reducing means and the required torque reduction amount. This facilitates setting of the torque increase amount. The torque increasing means can increase the torque by at least one of the enrichment of the air-fuel ratio and the increase of the intake air amount. In this way, the torque increase can be performed simply and accurately. It is preferable for performing the above.

Filter means for extracting a resonance frequency component of the drive system of the vehicle from a value related to the engine load (for example, an intake air amount) is provided to reduce the required torque reduction amount and the resonance frequency component extracted by the filter means. It can also be obtained as a value to be performed. By doing so, it is possible to detect that the vehicle is in an acceleration state in which acceleration vibration occurs without storing a large number of various acceleration modes in which acceleration vibration occurs. The magnitude of the required torque reduction amount for which vibration should be reduced can be set with high accuracy.

[0013]

According to the present invention, the increase in NOx can be reduced by performing the acceleration vibration reduction using the torque increase in addition to the acceleration vibration reduction using the torque reduction using the ignition timing retard and the fuel cut. Acceleration vibration can be appropriately reduced while preventing the vibration.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an engine body which is a multi-cylinder engine (in the embodiment, a spark ignition type in-line four-cylinder engine). Intake passage 2
Has a surge tank 3 in the middle, and an intake passage on the upstream side thereof is a common intake passage 4 common to each cylinder. In the common intake passage 4, an air cleaner 5, an air flow meter 6 as an engine load detecting means, and a throttle valve 7 are sequentially arranged from the upstream side to the downstream side. The intake passage 2 on the downstream side of the surge tank 3 is an independent intake passage 8 provided independently for each cylinder. The independent intake passage 8 has a fuel injection valve 9 as a fuel supply means.
Are arranged.

U in FIG. 1 is a control unit (controller) configured using a microcomputer.
The control unit U includes an intake air amount signal as a value related to the engine load detected by the air flow meter 6,
An engine speed signal detected by the engine speed sensor 10 and a gear ratio signal from a gear ratio detection sensor 11 that detects a gear position of the transmission, that is, a gear ratio, are input.
Further, the control unit U outputs a fuel injection amount signal to the fuel injector 9 and an ignition timing signal to an igniter 13 that controls the ignition timing of the ignition plug 12 for engine torque reduction control. .

FIG. 2 shows a change in the engine speed (same as a change in torque indicating vehicle vibration or a change in longitudinal acceleration of the vehicle) when the accelerator pedal is depressed all at once, that is, in a step response. When the accelerator pedal is depressed in a step response, substantially all of the frequency components are included, and therefore, the resonance frequency component of the drive system during acceleration is also included, and a large torque change occurs at the beginning of acceleration. (Increase). In particular, the first large torque increase at the beginning of acceleration, which is surrounded by a dashed circle in FIG. 2, is caused by an unpleasant vibration in which the drive system resonates. This prevents or suppresses a large drop in the torque of the motor, which is effective in effectively reducing the unpleasant vibration generated by the drive system.

In the present invention, control is performed so as to cancel the first torque peak of FIG. 2 by reducing the torque.
This torque reduction is performed by retarding the ignition timing when the reduction amount is small, and is performed by fuel cut when the reduction amount is large. In the present invention, when the torque to be reduced is medium, the valley of the torque generated next to the peak of the first torque, which is to be canceled by the torque reduction, is canceled (filled). , And control for increasing the torque. Note that these points will be described later in detail.

FIG. 3 shows the resonance frequency of the drive system for each gear position. In the example of FIG. 3, the resonance frequency is around 2 Hz at the first speed, around 4 Hz at the second speed, and 3 Hz.
At around 6Hz at 4th speed, around 8Hz at 4th speed,
At 5th speed, it is around 10 Hz. The resonance frequencies of 2 Hz to 10 Hz are all included when the accelerator pedal is stepped on.

The control unit U extracts a resonance frequency component corresponding to the gear position from the detected intake air amount signal in order to prevent the drive system from vibrating during acceleration, and extracts the resonance frequency component of the extracted resonance frequency component. After adjusting the phase to adjust the torque to the fuel injection timing, control is performed to reduce the engine torque by the amount of the resonance frequency component torque, and if necessary, use the torque increase to reduce the acceleration vibration. Control. The control content of such a control unit U is
FIG. 4 is a schematic diagram.

FIG. 4 will be described.
The time is set based on the fuel injection timing. First, the intake air amount signal detected by the air flow meter 6 is input to the band-pass filter 21 in a manner indicated by reference numeral 31. The filter coefficient of the band-pass filter 21 is set and changed so as to extract a resonance frequency component corresponding to the gear position, and a resonance frequency component corresponding to the gear position is output. Is shown.

The output from the band-pass filter 21 is advanced in phase by one ignition at the ignition timing by the phase matching means 22, and the phase-advanced resonance frequency component is indicated by reference numeral 33. This phase matching (phase correction) is preferably performed using at least one of the engine speed and the gear ratio as a parameter. The magnitude of the torque of the resonance frequency component after the phase matching is set as a reduction amount of the engine torque by the reduction torque conversion means 23, and the set reduction amount of the engine torque is indicated by reference numeral 34.
Indicated by

FIG. 5 is a flowchart more specifically showing the control contents of the control unit U shown in FIG. 4. This flowchart will be described below. In the following description, Q indicates a step. First, in Q1, various data of the intake air amount, the engine speed, and the gear position are read. In Q2, a resonance frequency according to the current gear position is set. In Q3, the filter coefficient of the band-pass filter 21 is set based on the gear position and the engine speed. The filter coefficient sets the center value of the resonance frequency and the size of the band before and after the center value. The bandpass filter can be, for example, a two-dimensional digital filter, and its transfer function H (z) is expressed by the following equation using the following five filter coefficients a0, a1, a2, b1, and b2. (Where "-2" is "minus square"), Q
Step 3 is a process for setting (changing) these five filter coefficients.

H (z) = (a0.z-2 + a1.z + a
2) / (z−2 + b1 · z + b2)

In Q4, it is determined whether or not the intake air amount as the engine load is under a high load of a predetermined value or more.
When the determination of Q4 is NO, that is, when the load is low, it is determined that the control for reducing the engine torque is unnecessary, and the routine is returned as it is. If the determination in Q4 is YES, the resonance frequency component is extracted in Q5 (corresponding to the processing of the band-pass filter 21 in FIG. 3). Next, in Q6, the phases of the extracted resonance frequency components are adjusted (corresponding to the processing of the phase matching unit 22 in FIG. 3).

In Q7, the reduction rate of the engine torque for reducing the extracted resonance frequency component is calculated (corresponding to the processing of the reduced torque conversion means 23 in FIG. 3). This Q7
Is the intake air amount detected by the air flow meter 6 is Ce, and the resonance frequency component extracted by Q5 is C
If it is esnf, it will be a value indicated by “Cesnf / Ce”.

After Q7, the engine torque is reduced so as to achieve the above-described torque reduction rate (process of Q10). However, in the embodiment, the processes of Q8 and Q9 are separately set to cope with the case where the transmission is a continuously variable transmission. That is, in Q8, it is determined whether or not there is a change in the gear ratio. If the determination is YES, in Q9, the transmission of the continuously variable transmission is assumed to be a continuously variable transmission. Is corrected so that the amount of reduction of the engine torque is reduced by the amount corresponding to the inertia associated with.
The torque corresponding to the inertia in Q9 is calculated by multiplying “(current gear ratio−previous gear ratio) / engine speed” by a predetermined conversion coefficient. When the determination in Q8 is NO or after Q9, the engine torque is reduced in Q10, respectively.

The torque down control at Q10 in FIG. 5 includes a torque down control by retarding the ignition timing and a torque down control by fuel cut.
Torque increase control is also performed so as to fill a valley of torque generated after the first torque peak in FIG. That is, when the required torque reduction amount (the torque reduction rate set by Q7 in FIG. 5) is as small as 30% or less as the first set value, the torque is reduced by retarding the ignition timing. When the required torque reduction amount is as large as, for example, 70% or more as the second set value, the torque is reduced by the fuel cut. When the required torque reduction amount is in the range between the first set value and the second set value, that is, in the range between 30% and 70%, at the timing when the valley of the torque to be filled in FIG. Thus, a torque increase is performed. This increase in torque can be obtained, for example, by performing at least one of an increase in the amount of intake air and an increase in the air-fuel ratio (correction of an increase in the fuel injection amount).

The details of Q10 in FIG. 5 will be described with reference to the flowchart in FIG. First, in Q21, the torque reduction amount to be reduced (the torque reduction rate in the embodiment) is equal to the first set value (for example, 30).
%) Is determined. If the determination in Q21 is NO, in Q22, the torque is reduced by retarding the ignition timing.

If the determination in Q21 is YES, it is determined in Q23 whether or not the amount of torque reduction to be reduced is smaller than a second set value (for example, 70%). This Q2
If the determination in Step 3 is NO, in Q24, the torque is reduced by the fuel cut.

If the determination in Q23 is YES, the torque reduction amount to be reduced is in the range between the first set value and the second set value. In this case, first, in Q25, the ignition timing is set to the maximum retardation amount within a range that does not cause misfire.
Next, in Q26, the amount of torque reduction at the portion indicated as the valley of the torque to be filled in FIG. 2 is calculated. This can be set according to the required torque reduction amount. Percentage (for example, 70
%).

Thereafter, a torque increase amount is calculated as a torque increase amount corresponding to the torque decrease amount calculated in Q26 (for example, calculation of an increase in intake air amount corresponding to a required torque increase amount, Calculation of the correction for increasing the injection amount). Then, in Q28, when the timing at which the valley of the torque that occurs after the first torque peak is confirmed can be confirmed, the torque is increased in Q29.

Here, the torque increase amount in Q27 can be a torque difference obtained by subtracting the torque reduction amount reduced by setting the maximum retard amount from the required torque reduction amount to be reduced. That is, by retarding the ignition timing, the peak of the first torque of the acceleration vibration is considerably reduced, if not sufficient, so that the valley of the torque generated next also retards the ignition timing. It becomes smaller than the case without. Therefore, by setting a torque reduction amount that is insufficient only by retarding the ignition timing as the torque increase amount, it is preferable to prevent a situation where the torque increase amount is erroneously set too large.

Although the embodiment has been described above, the present invention is not limited to this and includes, for example, the following case. The type of the engine is not particularly limited, such as a V-type engine, a diesel engine, and an engine with a supercharger. As the value relating to the engine load, an accelerator opening, a throttle opening, an intake negative pressure, an intake flow velocity and the like can be appropriately selected in addition to the intake air amount. An appropriate method can be adopted as a method for detecting the acceleration state that requires the torque reduction control.

Each step (step group) shown in the flowchart or various members such as a sensor and a switch can be expressed by adding a name of means to a higher-level expression of its function. Also,
The function of each step (step group) shown in the flowchart can also be expressed as a function of a function unit set in a control unit (controller) (existence of a function unit). Of course, the objects of the present invention are not limited to those explicitly stated, but also implicitly include providing what is substantially preferred or expressed as advantages. Further, the present invention can be expressed as a control method.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of an engine to which the present invention is applied.

FIG. 2 is a diagram illustrating an example of vibration caused by resonance of a drive system during acceleration.

FIG. 3 is a diagram illustrating an example of a resonance frequency according to a gear position.

FIG. 4 is a block diagram showing the control contents of the present invention.

FIG. 5 is a flowchart showing a control example of the present invention.

FIG. 6 is a flowchart showing control of reduction and increase of torque.

[Explanation of symbols]

 1: engine body 2: intake passage 6: air flow meter (engine load detecting means) 9: fuel injection valve 10: engine speed sensor 11: gear position sensor 12: spark plug 13: igniter 21: band pass filter (resonant frequency component) Extraction) 22: Phase matching means 23: Reduced torque conversion means U: Control unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 45/00 364 F02D 45/00 364D F02P 5/15 F02P 5/15 F (72) Inventor Shingo Harada Hiroshima 3-1, Shinchi, Fuchu-cho, Aki-gun, Mazda Co., Ltd. (72) Inventor Akitomo Kume 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. F-term (reference) BA13 BA17 CA04 DA39 EA01 EB02 FA06 FA07 FA10 FA33 3G301 HA06 JA04 JA37 KA12 KB01 LB01 MA01 MA12 MA24 NB07 NE01 NE07 NE13 PA01Z PA11Z PE01Z PE06Z

Claims (5)

[Claims] 1. A control apparatus for a vehicle engine, comprising: a torque reduction unit for determining a required torque reduction amount required for reducing acceleration vibration during acceleration and reducing engine torque by the required torque reduction amount. The torque reduction means reduces the engine torque by retarding the ignition timing when the required torque reduction amount is smaller than the first set value, and sets the required torque reduction amount to a value larger than the first set value. When it is larger than the second set value, the engine torque is set to be reduced by the fuel cut. When the required torque reduction amount is between the first set value and the second set value, At the timing of the torque valley that occurs next to the timing of the torque peak to be reduced by the torque reduction means in the acceleration vibration, the torque valley is small. Torque increasing means for increasing the engine torque such that is provided, the control device for a vehicle engine, characterized in that. 2. The method according to claim 1, wherein when the required torque reduction amount is between the first set value and the second set value, the torque reduction means sets the ignition timing to a maximum retard amount. A control device for a vehicle engine, which retards the angle. 3. The torque increase means according to claim 2, wherein the torque increase means increases the torque by a torque corresponding to a difference between the torque reduction amount obtained by the maximum retardation of the ignition timing by the torque reduction means and the required torque reduction amount. A control device for a vehicle engine. 4. The control device for a vehicle engine according to claim 1, wherein said torque increasing means increases the torque by at least one of enrichment of an air-fuel ratio or increase of an intake air amount. 5. The vehicle according to claim 1, wherein an engine load detecting means for detecting a value related to the engine load, and a value of the engine load detected by the engine load detecting means. Filter means for extracting a resonance frequency component of the drive system, wherein the required torque reduction amount is determined to be a value for reducing the resonance frequency component extracted by the filter means. Engine control device.