JP4606482B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device, and more particularly to an engine control device that controls throttle opening and idle rotation during idling.

In recent years, engine output shaft torque, which is a physical quantity that directly affects vehicle control, is used as a required value for driving force from the driver or vehicle side, and this is used as a target value for engine output. Techniques have been proposed for obtaining good running performance by determining the amount and ignition timing.
In addition, it is generally known that the amount of engine control that has the greatest influence on engine output shaft torque is the intake air amount, and a technique for controlling the intake air amount with high accuracy is also proposed. Has been.

  In an engine control device that controls the throttle opening by driving an actuator connected to the engine throttle, the target intake air amount corresponding to the target torque of the engine is based on the pressure before and after the throttle, the air passage area, and the flow coefficient. The target effective opening area of the throttle, which is the product of the opening area of the throttle and the flow coefficient, is obtained, and the target throttle opening is determined using the relationship between the effective opening area and the throttle opening that is adapted in advance. By calculating, we propose a means to calculate the throttle opening to accurately obtain the target intake air amount even when environmental conditions such as atmospheric pressure and intake air temperature change or when exhaust gas is introduced into the intake pipe (For example, refer to Patent Document 1).

However, the above-described configuration has a problem that the actual intake air amount varies with respect to the target intake air amount due to variations in the throttle body and various sensors and various estimation errors.
Therefore, when calculating the throttle opening for obtaining the target intake air amount, the target throttle opening is learned and corrected so that the target intake air amount can be satisfactorily achieved with respect to variations in the throttle body and various sensors and various estimation errors. Throttle opening learning means has been proposed.

In addition, the throttle opening correction amount is calculated so that the intake amount estimated from the throttle opening and the engine rotation is equal to the actually detected intake amount in the idling state, and the target intake amount is obtained by the correction amount. Air amount learning correction means for learning and correcting the target throttle opening so that the engine output can be obtained while adjusting the throttle opening so that the engine rotation becomes the target engine rotation in the idle operation state. Friction learning means for learning and correcting the degree, and learning by the friction learning means is performed after the learning by the air amount learning means has converged (for example, see Patent Document 2).
In this system, the engine output is controlled to the target engine output with high accuracy by performing learning correction on the change in the opening area over time due to dirt or clogging of the throttle body.

JP 2007-239650 A Japanese Patent No. 3445500

However, in the method proposed in Patent Document 1, the throttle opening learning means and the idle rotation control and the idle rotation learning control for converging the engine rotation to the target engine rotation at the time of idling are operated simultaneously. There is a concern that the mutual correction amounts overlap and cause interference, resulting in engine hunting or engine stall.
In addition, since learning by the throttle opening learning means and idle rotation control is performed at the same time, the correction amount that each learning correction should originally learn cannot be distinguished, and the learning accuracy may be deteriorated. .

Further, as in the device described in Patent Document 2, after the learning value by the air amount learning correction means for learning correction of the change in the throttle opening during idling converges, the engine rotation becomes the target engine rotation. Even in the method of correcting and correcting the engine output, feedback control for converging the engine speed to the target engine speed is performed. Therefore, there is a concern that hunting or engine stall of the engine rotation may occur due to interference with the air amount learning correction. There is.
Further, since it is configured to determine whether or not the air amount learning has converged based on the number of learning updates, there is a concern that the learning may end even if the air amount learning is not completed. In addition, if the air amount learning is performed when the engine rotation is not stable, a detection delay of the intake air amount may occur due to a surge tank, intake manifold, etc., which may lead to erroneous learning of the air amount. There is.

  The present invention improves the idle stability by preventing mutual interference between the throttle opening learning correction means and the idle rotation control in the idle operation state, and the learning value that can improve the calculation accuracy of the learning value by each learning correction It aims at providing the control apparatus of an engine provided with an adjustment means.

An engine control apparatus according to the present invention includes an operation state detection unit that detects an operation state of an internal combustion engine, and an idle rotation control that performs feedback control so that the engine rotation speed becomes a target engine rotation speed during idling in an idle operation state. Means, idle rotation learning control means for calculating an idle rotation learning value based on a feedback amount calculated by the idle rotation control means, engine output calculation means for setting a target output of the internal combustion engine, and the target output; From the intake air amount calculating means for calculating the target intake air amount based on the engine speed, the target throttle opening degree calculating means for calculating the target throttle opening amount from the target intake air amount, and the actual intake air amount detected by the operating state detecting means Learning throttle opening calculating means for calculating the learning throttle opening; Calculate the throttle opening learning value based on the difference between the throttle opening and the learning throttle opening, and calculate the corrected throttle opening by correcting the target throttle opening with the throttle opening learning value An engine control device comprising: a learning correction means; a throttle opening learning correction execution permission means for permitting execution of a throttle opening learning correction under a predetermined condition in an idling state; and the throttle opening learning correction means. A throttle opening reverse calculation means for calculating an intake amount equivalent to the throttle opening after learning correction by performing a reverse calculation of the calculation executed by the throttle opening calculation means based on the calculated throttle opening after learning correction; Based on the intake air amount corresponding to the throttle opening after learning correction, the inverse operation of the operation executed by the intake air amount calculating means is performed. And intake air amount inverse calculating means for calculating an engine output of the learning corrected throttle opening angle Te, in a state where the throttle opening learning correction is permitted by the throttle opening learning correction execution permission means, the learning corrected throttle opening And an idling learning value adjusting means for adjusting the idling rotation learning value based on the difference between the engine output corresponding to the degree and the target output .

  The effect of the engine control device according to the present invention is that, even when the throttle opening learning correction and the idle rotation control are simultaneously operated, the correction amounts are adjusted so as not to interfere with each other. It can be suppressed.

FIG. 1 is a schematic configuration diagram of an internal combustion engine according to an embodiment of the present invention.
An internal combustion engine (hereinafter referred to as an engine) 19 according to an embodiment of the present invention is a four-cylinder four-cycle engine. Pistons 20 are fitted into the four cylinders 18 (18a to 18d), and a combustion chamber 21 is formed above the pistons 20. The piston 20 is connected to the crankshaft 23 via a connecting rod 22.

  A spark plug 10 is provided above the combustion chamber 21 of each cylinder 18. An intake port 5 and an exhaust port 11 are opened to the combustion chamber 21 of each cylinder 18, and an intake valve 6 and an exhaust valve 9 are provided in the intake port 5 and the exhaust port 11, respectively. The intake valve 6 and the exhaust valve 9 are driven by a valve operating mechanism including a camshaft (not shown). The opening / closing timing of the intake valve 6 and the exhaust valve 9 of each cylinder is set so that each cylinder 18 performs a combustion cycle with a predetermined phase difference. A fuel injection valve 7 is provided in the intake port 5.

  An intake passage 24 and an exhaust passage 25 are connected to the intake port 5 and the exhaust port 11, respectively. The intake passage 24 has a throttle 2 that adjusts the intake air amount upstream of the surge tank 4, and the throttle actuator 1 adjusts the opening of the throttle 2. The opening degree of the throttle 2 is detected by a throttle position sensor 34. An airflow sensor 3 that detects the amount of air taken into the engine 19 through the intake port 5 when the throttle 2 opens and closes is disposed upstream of the throttle 2. Further, an intake air temperature sensor 33 for measuring the intake air temperature is provided integrally with or separately from the airflow sensor 3. Note that means for estimating the intake air temperature may be used instead of the intake air temperature sensor 33 for measuring the intake air temperature.

The surge tank 4 is provided with an intake manifold pressure sensor 35 that measures the pressure in the surge tank 4. Instead of providing the intake manifold pressure sensor 35 that measures the intake manifold pressure, a means for estimating the intake manifold pressure may be used. Further, an EGR valve 36 is connected to the surge tank 4.
Further, the exhaust passage 25 is provided with an oxygen concentration sensor 12 for detecting the oxygen concentration in the exhaust, and has a three-way catalyst 13 as a harmful gas purification device in the exhaust.

A crank plate 14 is attached to the crank shaft 23, and a plurality of detected teeth 15 are provided around the crank plate 14.
In order to detect the rotation angle of the crankshaft 23, a crank angle sensor 16 is provided and attached so as to output a crank angle signal. Further, a cam angle sensor 27 is provided that can give a cylinder identification signal to the camshaft 28 by detecting its specific rotational position.
Further, auxiliary devices such as a vehicle generator 29, an air conditioner compressor 31, or a steering oil pump 30 are rotationally driven by a crankshaft 23 via a belt 32, and sensor information from each auxiliary device is ECU (engine control). Unit) 17.

In addition, a water temperature sensor 26 for detecting the temperature of the engine cooling water, an accelerator opening sensor 37 (see FIG. 2) for detecting the accelerator opening, an atmospheric pressure sensor not shown, and the like are provided. The signals from the sensors are input to the ECU 17, and the ECU 17 calculates the target engine output from the various input data, the target intake air amount that achieves the calculated target engine output is calculated, and the target intake air amount is achieved. Calculate the target throttle opening.
Then, the opening degree of the throttle 2 is controlled so as to achieve the target throttle opening degree. At the same time, drive signals are output to various actuators including the fuel injection valve 7, the ignition coil 8, and the EGR valve 36.

FIG. 2 is a block diagram showing a configuration of ECU 17 according to the embodiment of the present invention.
In the engine output calculation means 17a, the accelerator opening detected by the accelerator opening sensor 37, the engine rotation Ne detected by the operation state detection means 17e (the target engine rotation Net in the idle operation state), the engine water temperature WT, The target output Pit to be generated by the engine is calculated from the engine output calculated based on sensor information from various auxiliary machines and the engine output necessary for causing the engine rotation to follow the target engine rotation in the idle operation state. .

The intake air amount calculating means 17b calculates a target intake air amount Qat from the engine output Pit calculated by the engine output calculating means 17a.
There are many known methods for setting the relationship between the engine output Pi and the intake air amount Qa with high accuracy. Here, as shown in FIG. 3, the relationship between the engine rotation Ne and the charging efficiency Ec with respect to the engine output Pi is shown in a map in advance. The intake air amount Qa is calculated using the charging efficiency Ec calculated from the map and the engine rotation Ne (target engine rotation Net in the idling state), etc. (instruction unit 39). .

The throttle opening calculation means 17c serving as the target throttle opening calculation means calculates the target throttle opening Tpt so as to achieve the target intake air amount Qat calculated by the intake air amount calculation means 17b.
The details of the throttle opening calculation means 17c will be described with reference to FIG.
A so-called throttling type flow meter volume flow rate calculation formula is expressed by equation (1). Here, the acoustic velocity of the air to a _0, to C a flow coefficient, the opening area of the At throttle, P _e the intake manifold pressure, the P ₀ atmospheric pressure, a κ specific heat ratio. Here, when the dimensionless flow rate σ is defined as Expression (2), Expression (1) is rewritten to Expression (3). Note that the sound velocity a ₀ in the atmosphere is expressed by equation (4), where R is a gas constant and T ₀ is the intake air temperature.

Here, when the intake air amount Qa necessary for achieving the engine output Pi calculated by the engine output calculating means 17a, the sound velocity a _{0 of} the atmosphere, and the dimensionless flow rate σ are given, the flow coefficient C and the throttle opening The effective opening area CAt represented by the product of the area At can be calculated by Expression (5) obtained by modifying Expression (3).

The effective opening area CAt is calculated from the intake air amount Qa, the atmospheric sound velocity a ₀ , and the dimensionless flow rate σ by the instruction unit 40 shown in FIG. Here, the atmospheric sound velocity a ₀ is calculated in advance as a theoretical value of the atmospheric sound velocity a ₀ and stored as a map of the intake air temperature T ₀ (instruction unit 41). Furthermore, for the dimensionless flow rate sigma required in operation S401, it is stored as the map of the pressure ratio between the intake manifold pressure P _e and the atmospheric pressure P ₀ by calculating the theoretical value of the dimensionless flow rate sigma (instruction unit 42, 43).
Using the CAt calculated by the instruction unit 40, the instruction unit 44 calculates the throttle opening degree Tp. At that time, the relationship between the throttle opening Tp and the effective opening area CAtr calculated from the equation (5) is measured using the throttle opening Tp and the actual intake air amount Qar measured by the airflow sensor 3 in advance. CAt is stored as a one-to-one corresponding two-dimensional map, and the throttle opening Tp is calculated from the effective opening area CAt by using this map.

When the throttle 2 is controlled to the target throttle opening Tpt calculated as described above, the target intake air amount Qat and the actual intake air amount detected by the airflow sensor 3 caused by variations in the throttle body and various sensors and various estimation errors are obtained. In order to reduce the error of Qar, the throttle opening degree learning correction means 17d uses the target throttle opening degree Tpt and the actual intake air amount Qar detected by the airflow sensor 3 as a learning throttle opening degree calculating means. Based on the difference in the learning throttle opening Tp _QA calculated by the opening calculation means 17c, the target throttle opening Tpt is corrected to calculate the learning corrected throttle opening Tp _LRN .

Further, as described above, in the idle operation state, the idle rotation control means 17g causes the target based on the deviation (ΔNe) between the engine rotation Ne and the target engine rotation Net so that the engine rotation Ne follows the target engine rotation Net. While the engine output Pit is feedback-corrected, the idle rotation learning control unit 17h performs idle rotation learning in order to eliminate ΔNe generated in an offset manner based on the feedback value Pi _FB calculated by the idle rotation control unit 17g. The value Pi _ISC is calculated.

Here, when the throttle opening degree learning correction execution permission unit 17f permits the execution of the throttle opening degree learning correction unit 17d in the idling state, the throttle opening degree learning correction unit 17d and the idle rotation control unit 17g are simultaneously performed. Each correction value interferes because it is executed. For this reason, under such circumstances, the throttle opening that performs the reverse operation of the calculation executed by the throttle opening calculation means 17c is based on the post-learning throttle opening Tp _LRN calculated by the throttle opening learning correction means 17d. every time the inverse calculation unit 17j calculates the learning corrected throttle opening angle of the intake air amount Qa _TP, based on the intake air amount Qa _TP of learning corrected throttle opening angle computed by the throttle opening inverse operation unit 17j, an intake The engine output Pi _TP corresponding to the throttle opening after learning correction is calculated by the intake air amount reverse calculation means 17k which performs reverse calculation of the calculation executed by the amount calculation means 17b.

A difference between the engine output Pi _TP corresponding to the throttle opening after learning correction calculated by the learning value adjusting means 17i during idling and the target engine output Pit calculated by the engine output calculating means 17a is obtained as an idle rotation learning control means 17h. Thus, the correction of the throttle opening and the correction of the engine rotation are made compatible by performing calculation so as to cancel out from the idle rotation learning value Pi _ISC calculated by the above.

Next, a specific operation of the control device according to the embodiment of the present invention will be described based on the flowchart of FIG.
First, in step S501 of FIG. 5, the actual throttle opening Tpr detected by the throttle position sensor 34 and the learning throttle opening Tp _QA calculated based on the actual intake air amount Qar detected by the airflow sensor 3 are calculated. Based on the difference, a throttle opening learning correction value ΔTp _LRN is calculated. At this time, the actual throttle opening degree Tpr and the target throttle opening degree Tpt substantially coincide with each other in the idle state, so that the target throttle opening degree Tpt may be used instead of the actual throttle opening degree Tpr.

In step S502, a learning corrected throttle opening Tp _LRN is calculated based on the sum of the throttle opening learning correction value ΔTp _LRN calculated in step S501 and the target throttle opening Tpt.

In steps S503 and S504, an intake air amount Qa _TP corresponding to the corrected learning throttle opening Tp _LRN is calculated by calculating the throttle opening reverse calculation means 17j.
First, in step S503, the effective opening area CAt _TP corresponding to the corrected learning throttle opening Tp _LRN is calculated using the above-described two-dimensional map of the throttle opening Tp and the effective opening area CAt.
Next, in step S504, the intake air amount Qa _TP corresponding to the corrected learning throttle opening Tp _LRN is calculated using the above-described equation (3) and the effective opening area CAt _TP calculated in step S502.

In step S505, the engine output Pi _TP corresponding to the corrected learning throttle opening Tp _LRN is calculated by performing the inverse operation of the operation executed by the intake air amount calculating unit 17b with the intake air amount reverse calculating unit 17k. First, the charging efficiency EC _TP is calculated using the intake air amount Qa _TP calculated in step S504 and the target engine rotation Net, and then the engine output Pi _TP is calculated using the aforementioned three-dimensional map of Pi, EC, and Ne. To do. At this time, the target engine rotation Net is used for engine rotation.

In step S506, an engine output ΔPi _TP corresponding to the throttle opening learning correction value ΔTp _LRN is calculated from the difference between the target engine output Pit and the engine output Pi _TP calculated in step S505.

  In step S507, it is determined whether or not the engine is in an idle state. If the engine is not in an idle state, the process proceeds to step S512, and the throttle opening learning correction is performed as usual, and the process is terminated. At this time, instead of determining the idle state, it may be determined whether idle rotation control or idle rotation learning control is being executed.

If it is determined in step S507 that the engine is in the idle state, the process proceeds to step S508, and the execution condition of the throttle opening learning correction at the time of idling is determined. Specifically, the deviation ΔNe of the target engine rotational Net and the actual engine speed becomes less than a predetermined value, and determines whether the state has elapsed the predetermined time above T _1. If the condition is not satisfied, the process proceeds to step S510, the throttle opening learning correction is prohibited, and the process is terminated.

If the execution condition of the throttle opening learning correction is satisfied in step S508, the process proceeds to step S509, and the end condition of the throttle opening learning correction at idling is determined. Specifically, the difference ΔQa the target intake air amount Qat and the actual intake air amount Qar becomes less than a predetermined value, and determines whether the state has elapsed the predetermined time T ₂ or more. If the condition is satisfied, the process proceeds to step S510, the throttle opening learning correction is prohibited, and the process is terminated.

If the completion condition of the throttle opening learning correction is not satisfied in step S509, the engine output ΔPi _TP calculated in step S506 is subtracted from the idle rotation learning value Pi _ISC in step S511, and at the same time, step In S512, the throttle opening learning correction is performed.

  Next, the specific operation of each control value in the present invention will be described based on the time chart of FIG.

In a state where the idle state is determined, first, the idle rotation feedback value Pi _FB is calculated so that the engine rotation Ne converges to the target engine rotation Net by the idle rotation control.

When the engine speed Ne falls within a predetermined value ΔNe with respect to the target engine speed Net by the idle speed control means 17g, the Ne counter starts counting (time t ₁ ). This Ne counter is normally also used as an execution condition for idle rotation learning control, and may be used together as an execution condition for throttle opening degree learning correction during idling.

The idle rotation learning control is executed in a state where the engine rotation Ne has converged within the predetermined value ΔNe, and the idle rotation learning value Pi _ISC is calculated based on the idle rotation feedback value Pi _FB (time t ₄ ).

Further, rotation of the engine Ne is converged within a predetermined value? Ne, after a predetermined time T ₁ is elapsed, the throttle opening degree learning correction is performed, the throttle opening degree learning correction value [Delta] Tp _LRN is calculated (time t ₅ ).

Here, based on the above-described means, the engine output ΔPi _TP corresponding to the throttle opening learning correction value ΔTp _LRN is calculated, and subtracted from the idle rotation learning value Pi _ISC , so that the throttle opening learning correction and the idle rotation control are performed. This prevents interference with the engine and suppresses engine rotation fluctuations.

When the difference ΔQa between the target intake air amount Qat and the actual intake air amount Qar becomes equal to or smaller than a predetermined value (time t ₆ ) and the state has exceeded a predetermined time T ₂ (time t ₇ ), the throttle opening learning correction is performed. It is terminated, and unnecessary interference with idle rotation control is prevented, and unnecessary fluctuations in engine rotation are prevented.

  In this way, by adjusting the correction amount so that the throttle opening learning correction and the idle rotation control do not interfere with each other in the idling state, the idle stability is improved and the learning value calculation accuracy by each learning correction is improved. can do.

1 is a schematic configuration diagram of an engine according to the present invention. It is a block diagram of the engine control apparatus which concerns on this invention. It is a block diagram which shows the intake air amount calculation means of the engine control apparatus which concerns on this invention. It is a block diagram which shows the throttle opening calculation means of the engine control apparatus which concerns on this invention. It is a flowchart which shows the operation | movement of the engine control which concerns on this invention. It is a time chart which shows operation of engine control concerning this invention. It is a figure which shows a behavior when engine rotation fluctuates by interference of idle rotation learning correction | amendment and idle rotation control.

Explanation of symbols

  1 throttle actuator, 2 throttle, 3 airflow sensor, 4 surge tank, 5 intake port, 6 intake valve, 7 fuel injection valve, 8 ignition coil, 9 exhaust valve, 10 ignition plug, 11 exhaust port, 12 oxygen concentration sensor, 13 Three-way catalyst, 14 crank plate, 15 detected teeth, 16 crank angle sensor, 17 ECU, 17a engine output calculating means, 17b intake air amount calculating means, 17c throttle opening calculating means, 17d throttle opening learning correcting means, 17e operation State detection means, 17f throttle opening learning correction execution permission means, 17g idle rotation control means, 17h idle rotation learning control means, 17i idle learning value adjustment means, 17j throttle opening reverse calculation means, 17k intake air amount reverse calculation means, 18 cylinders, 19 engines, 0 piston, 21 combustion chamber, 22 connecting rod, 23 crankshaft, 24 intake passage, 25 exhaust passage, 26 water temperature sensor, 27 cam angle sensor, 28 camshaft, 29 generator for vehicle, 30 oil pump for steering, 31 air conditioner compressor , 32 belt, 33 intake air temperature sensor, 34 throttle position sensor, 35 intake manifold pressure sensor, 36 valve, 37 accelerator opening sensor, 38, 39, 40, 41, 42, 44 indicator.

Claims (5)

An operating state detecting means for detecting an operating state of the internal combustion engine;
Idle rotation control means for performing feedback control so that the engine rotation speed becomes the target engine rotation speed during idling in the idle operation state;
Idle rotation learning control means for calculating an idle rotation learning value based on the feedback amount calculated by the idle rotation control means;
Engine output calculating means for setting a target output of the internal combustion engine;
An intake air amount calculating means for calculating a target intake air amount based on the target output and the engine rotation;
Target throttle opening calculating means for calculating the target throttle opening from the target intake air amount;
Learning throttle opening calculating means for calculating the learning throttle opening from the actual intake air amount detected by the operating state detecting means;
Throttle that calculates a throttle opening learning value based on a difference between the target throttle opening and the learning throttle opening, and calculates a corrected corrected throttle opening by correcting the target throttle opening by the throttle opening learning value Opening learning correction means;
In an engine control device comprising:
Throttle opening learning correction execution permission means for permitting execution of the throttle opening learning correction under predetermined conditions in an idle operation state;
A throttle that calculates the intake amount corresponding to the throttle opening after learning correction by performing the reverse operation of the calculation executed by the throttle opening calculation means based on the throttle opening after learning correction calculated by the throttle opening learning correction means Opening reverse calculation means;
An intake air amount inverse calculation means for calculating an engine output equivalent to the throttle opening after learning correction by performing an inverse operation of the calculation executed by the intake air amount calculation means based on the intake air amount corresponding to the throttle opening after learning correction;
When the throttle opening learning correction is permitted by the throttle opening learning correction execution permission means , the idle rotation learning value is adjusted by the difference between the engine output corresponding to the throttle opening after the learning correction and the target output. An idle learning value adjustment means to be performed;
An engine control device comprising: The idle learning value adjustment means includes:
Calculating an engine output corresponding to the learning corrected throttle opening degree, and at the same time correcting the idle rotation learning value based on a difference between the engine output of the corrected throttle opening angle which is calculated with the target engine output, the 2. The engine control device according to claim 1, wherein the throttle opening is controlled by the throttle opening after learning correction.   The throttle opening learning correction execution permission means is the throttle opening learning correction means when the absolute value of the deviation between the engine rotation and the target engine rotation detected by the operation state detection means in an idle operation state is a predetermined value or less. The engine control device according to claim 1 or 2, wherein the learning correction of the throttle opening by means of the engine and the adjustment of the idle rotation learning value by the idle time learning value adjusting means are executed.   The throttle opening learning correction execution permission means, when the absolute value of the deviation between the engine rotation detected by the operation state detection means and the target engine rotation in the idle operation state is not more than a predetermined value and continues for a predetermined time, The engine according to any one of claims 1 to 3, wherein learning correction of the throttle opening by the throttle opening learning correction means and adjustment of an idle rotation learning value by the idle learning value adjustment means are executed. Control device. The throttle opening learning correction execution permission means is
When the absolute value of the difference between the target intake air amount and the actual intake air amount is equal to or less than the predetermined value for a predetermined time, it is determined that the throttle opening learning during idling has been completed, and the throttle opening by the throttle opening learning correcting means is determined. The engine control device according to any one of claims 1 to 4, wherein the learning correction of the degree and the adjustment of the idle rotation learning value by the idle learning value adjusting means are prohibited.

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