JP2004138078A - Engine idle rotation learning control device - Google Patents

Abstract

An object of the present invention is to reduce a variation in learning by preventing a variation in rotation caused by switching to homogeneous stoichiometric combustion from being included in a learning value.
SOLUTION: Before checking whether a learning permission condition is satisfied, it is first determined whether or not the vehicle is in a steady state (S1). It is determined whether the learning permission condition is satisfied in the determined state (S3).
[Selection diagram] FIG.

Description

The present invention relates to an idle rotation learning control device for an engine, and more particularly, to a device for learning and correcting the change of the intake opening area of the engine with time due to dirt or the like.

In the throttle portion, dirt due to the blowback due to EGR and the like accumulates in the throttle portion, and even if the throttle is opened by the same amount, the throttle opening area decreases gradually but gradually. The idle air amount learning value corresponding to is introduced, and the idle air amount is reduced when a predetermined learning condition is satisfied while the intake air amount of the engine is feedback-controlled so that the actual rotation speed approaches the target idle rotation speed during idling. There is one that updates the idle air amount learning value based on the feedback correction amount (see Patent Document 1).
JP-A-61-210428

By the way, in the latter half of the compression stroke, the fuel is directly injected into the cylinder, and a flammable mixture is formed near the ignition plug at the time of ignition. In order to perform stable combustion and greatly improve fuel efficiency and exhaust composition, and to generate high output at high load, etc., shift the fuel injection timing to the intake stroke, mix the fuel and air in advance, 2. Description of the Related Art There is known an engine which performs homogeneous combustion (hereinafter, referred to as "homogeneous stoichiometric combustion") using an air-fuel mixture near a stoichiometric air-fuel ratio.

In such an engine, stratified combustion is performed in a low-speed and low-load region including idling. However, when the above-described conventional idle speed learning control is applied to such an engine as it is, the idling air amount in the stratified combustion state is reduced. The learning value will be updated.

However, during stratified charge combustion, the required air amount of the engine is larger than during homogeneous stoichiometric combustion, and therefore the proportion of the decrease in idle air amount due to dirt to the total intake air amount is small. When the air amount learning value is updated, the accuracy of the learning value decreases.

(4) For this reason, it has been previously proposed that the learning is performed in a state in which the stratified combustion is forcibly switched to the homogeneous stoichiometric combustion when the learning permission condition is satisfied (see Japanese Patent Application No. 9-179681).

According to this device (hereinafter, referred to as the prior application device), when the homogeneous stoichiometric combustion is switched, the proportion of the decrease in the intake air amount due to dirt to the total intake air amount is the same as in the past. This prevents the accuracy of the learning value from being reduced.

By the way, subsequent experiments showed that there was an improvement in the prior application. This is because if the learning condition is satisfied and the learning is started immediately after forcibly switching to the homogeneous stoichiometric combustion, even the amount of rotation fluctuation accompanying the switching of the combustion mode is included in the feedback correction amount of the idle air amount. Therefore, there is a possibility that an error corresponding to the rotation fluctuation may occur in the learning value. The learning value is originally used to compensate for the decrease in the intake air amount due to the dirt accumulated on the throttle portion when the throttle opening and the rotation speed are kept constant. Therefore, it is not appropriate to update the learning value in a state where the rotation fluctuation occurs.

Therefore, the present invention first determines whether the vehicle is in a steady state before checking whether the learning permission condition is satisfied, and issues a homogeneous stoichiometric combustion request when the vehicle is in the steady state, and determines that the vehicle is in the steady state. An object of the present invention is to reduce the learning variation by checking whether or not the learning permission condition is satisfied in a state in which the learning is performed, so that the rotation variation accompanying the switching of the combustion mode is not included in the learning value.

In the first invention, as shown in FIG. 7, a throttle valve 21 driven by an actuator 22 and a means for calculating a throttle opening basic value from which a steady engine torque value corresponding to an accelerator opening and an engine speed can be obtained. 23, a means 24 for storing a learning value corresponding to a temporal change in the opening area of the throttle valve portion, a means 25 for calculating a feedback correction amount so that the idle speed matches the target idle speed, An engine idling system comprising: means for correcting the throttle opening basic value based on the feedback correction amount and the learning value to obtain a throttle opening command value; and means 27 for providing the throttle opening command value to the actuator 22. The rotation learning control device switches the combustion mode between stratified combustion and homogeneous stoichiometric combustion according to the operating conditions. Means for performing combustion control so as to achieve stratified combustion when idling, means 29 for determining whether or not the engine is in a steady state, and forcing the combustion mode to the homogeneous stoichiometric combustion when it is determined that the engine is in a steady state. Means 30 for switching over time, and means 31 for updating the learning value based on the feedback correction amount when a learning permission condition is satisfied in a state where it is determined that the vehicle is in a steady state.

According to the first aspect, when the rotation is changed due to the switching to the homogeneous stoichiometric combustion, the learning value is not updated while the learning permission condition is satisfied while the engine is not in the steady state. In addition, the learning value does not include the amount of rotation fluctuation associated with switching to homogeneous stoichiometric combustion, thereby reducing learning variations.

In FIG. 1, 1 is an engine body, 2 is an intake pipe, and 3 is an electronically controlled throttle device (mainly composed of a throttle valve 3A and a step motor 3B for driving the throttle valve 3A) driven by a signal from the control unit 11.

The control unit 11 converts a signal from an accelerator opening sensor (not shown) into a value corresponding to the accelerator opening, and a steady engine torque value corresponding to this value and the number of revolutions (detected by the engine revolution sensor 12) at that time. Is calculated by searching a predetermined map or the like, a basic value of the throttle opening at which the steady torque is obtained is calculated, and the basic value of the throttle opening is given to a step motor 3B which is an actuator of the throttle device 3.

通路 Since no path bypassing the throttle valve 3A is provided, feedback control of the idle speed, which will be described later, is executed using the throttle valve 3A.

In addition to such a throttle device 3, a fuel injection valve 4 provided directly to a cylinder of each cylinder, a piston 6 having a cavity formed on the top surface in consideration of a position of a spark plug 5, a swirl control valve (not shown), etc. In the cylinder direct fuel injection type spark ignition engine, the fuel is injected in the latter half of the compression stroke in a low rotation speed and a low load region including an idling state. A combustible air-fuel mixture is formed in a nearby cavity, and stratified combustion of the fuel is caused by ignition by the ignition plug 5, and ultra-lean combustion with an air-fuel ratio exceeding 40 as a whole is performed.

In the high engine load range, fuel is injected during the intake stroke to speed up the mixing of fuel and air, fill the entire combustion chamber with a homogeneous mixture, and perform homogeneous combustion (homogeneous stoichiometry) with a mixture near the stoichiometric air-fuel ratio. Combustion). Further, in the intermediate load region between the stratified combustion region and the homogeneous stoichiometric combustion region, lean combustion (homogeneous lean combustion) is performed, which is richer in air-fuel ratio than stratified combustion but thinner than the stoichiometric air-fuel ratio. In some cases, fuel is injected in two stages, an intake stroke and a compression stroke.

In addition, 12 is a crank angle sensor, 13 is an air flow meter, 14 is a water temperature sensor, 15 is an O ₂ sensor, and 16 is a throttle sensor.

Dirt accumulates in the throttle part due to blowback by EGR and the like, and even if the throttle is opened by the same amount, the throttle opening area decreases over time. The idle air amount learning value is introduced, and a value obtained by adding the idle air amount learning value to the above throttle opening basic value is used as a throttle opening command value. In some systems, the feedback control of the intake air amount of the engine is performed so as to approach, and the idle air amount learning value is updated based on the feedback correction amount of the idle air amount when a predetermined learning permission condition is satisfied.

When such conventional idle air amount learning control is directly applied to the above-described in-cylinder direct fuel injection type spark ignition engine, the idle air amount learning value is updated in the state of stratified combustion.

However, during stratified charge combustion, the required air amount of the engine is larger than during homogeneous stoichiometric combustion, and therefore the proportion of the decrease in idle air amount due to dirt to the total intake air amount is small. When the air amount learning value is updated, the accuracy of the learning value decreases.

Therefore, in the prior application, the learning is performed in a state where the stratified combustion is forcibly switched to the homogeneous stoichiometric combustion when the learning permission condition is satisfied. According to the prior application, in the state switched to the homogeneous stoichiometric combustion, the decrease in the intake air amount due to dirt accounts for a larger proportion of the total intake air amount as in the past, thereby lowering the accuracy of the learning value. That can be avoided.

By the way, subsequent experiments showed that there was an improvement in the prior application. This is because if the learning conditions are satisfied and the learning value is started immediately after forcibly switching to the homogeneous stoichiometric combustion, the amount of rotation fluctuation accompanying the switching of the combustion mode is included in the feedback correction amount of the idle air amount. Therefore, an error corresponding to the rotation variation occurs in the learning value.

Therefore, in the first embodiment of the present invention, it is first determined whether or not the engine is in a steady state before checking whether the learning permission condition is satisfied. By checking whether the learning permission condition is satisfied in the state where it is determined that the state is the state, it is possible to reduce the learning variation by not including the rotation variation due to the switching of the combustion mode in the learning value. .

The details of the control executed by the control unit 11 will be described with reference to FIG.

FIG. 2 is for calculating the idle rotation learning opening TDTVO, and is executed at regular intervals (for example, every 10 ms).

In step 1, it is determined whether or not the vehicle is in a steady state. The following conditions,
<1> The rotational speed NE is within a predetermined range,
<2> No load fluctuation such as auxiliary equipment load,
<3> When all of the vehicle speeds satisfy zero, it is determined that the vehicle is in the steady state, and the process proceeds to step 2, where the homogeneous stoichiometric combustion request flag is set to "1" (that is, homogeneous stoichiometric combustion is requested).

を 受 け When this request flag has not been switched to homogeneous stoichiometric combustion in the previous job, stratified combustion is switched to homogeneous stoichiometric combustion.

In step 3, it is determined whether the learning permission condition is satisfied. Here, the learning permission conditions include
<4> being idle;
<5> The vehicle speed is zero,
<6> The heater fan switch, the air conditioner switch, and the electric load switch may all be OFF, and when all of these conditions are satisfied, the learning permission condition is satisfied.

(4) When the learning permission condition is satisfied, the routine proceeds to step 4, where an idle air amount learning value QTASEEP1 is calculated. In detail, the feedback correction amount of the idle air amount is obtained according to the difference between the actual rotation speed NE and the target idle rotation speed NSET by the feedback control of the idle rotation speed. At the timing when a predetermined number of samplings are performed, the average value of the predetermined number of feedback correction amounts is calculated, and the weighted average value of the average value and the idle air amount learning value at the timing at which the average value is calculated is calculated as a new idle value. Update as the air amount learning value. This idle air amount learning value QTASEEP1 is stored in a memory (for example, a flash memory) when the engine is stopped.

{Circle over (5)} In step 5, the integrated value ADDNE of the engine speed NE from the time when the vehicle is completely assembled on the assembly line in the factory is compared with a predetermined value GRNE. If the rotational speed integrated value ADDNE is less than the predetermined value GRNE, the routine proceeds to step 6, in which a value obtained by subtracting the offset amount TASOFS (constant value) from the idle air amount learning value QTASEEP1 is newly set as the idle air amount learning value QTASEEP. Correct the idle air amount learning value. When the rotational speed integrated value ADDNE is equal to or greater than the predetermined value GRNE, the process proceeds from step 5 to step 7, where the idle air amount learning value is not corrected (QTASEEP1 = QTASEEP1).

Here, the reason why the learning value is reduced by the offset amount when the rotational speed integrated value ADDNE is less than the predetermined value GRNE is that the required idle air amount at the beginning of the completion of the assembly due to the initial friction is large. is there.

詳述 More specifically, when the vehicle leaves the assembly line in the factory, the engine is operated for the first time. In the inspection line, a predetermined inspection is performed while the engine is operating, and after passing this inspection, an idle air amount learning value is calculated and stored for the first time according to a command from an external tool. Then, it is shipped from the factory in the state of the first learning value.

In this case, the sliding portion of the engine may not be smooth at the beginning of the assembly, and the amount of air required to maintain the same idling speed is large, and as the operation is continued (the rotation speed integrated value ADDNE increases). The required idle air amount drops rapidly, and eventually converges to a constant value. FIG. 3 shows this process. As shown in FIG. 3, the learning value calculated in this state is increased as the learning proceeds in the factory, because the required idle air amount is not converged before learning. It changes to the smaller side.

However, while the required idle air amount sharply decreases, the learning value update speed is not so fast, so it is delayed to catch up with the actual engine state, during which the learning value becomes excessively large, and the idle speed is increased. Is shifted by the error of the learning value.

Therefore, when the rotational speed integrated value ADDNE is less than the predetermined value GRNE, it is determined that the required idle air amount is before convergence, and it is predicted that the required idle air amount will eventually settle to a smaller value. The idle air amount learning value obtained before the convergence of the amount is corrected to a smaller value.

In this way, considering that the required idle air amount at the beginning of the assembly completion is larger than after shipment, the learning value is reduced and corrected until the required idle air amount converges. It is possible to eliminate the deviation of the idle air amount correction based on the learning value between the learning time of the learning and the learning time after the shipment.

After correcting the idle air amount learning value in this way, the corrected idle air amount learning value QTASEEP is multiplied by a flow area conversion coefficient CCONVA # in step 8 to obtain a throttle opening area learning value ATASLN. And convert.

{Circle around (9)} In step 9, the throttle opening area learning value ATASLN is converted into a throttle opening using a predetermined table. The conversion to the throttle opening will be described with reference to FIG.

に お い て In FIG. 4, the curve shown is the flow rate characteristic in the initial state.

(1) Assuming that the throttle opening at the time of updating the learning value is TVOM, the throttle opening area (that is, the throttle opening area at the time of updating the learning value) AAM at the intersection of a straight line and a curve that rises vertically from the TVOM is obtained.

(2) A value obtained by subtracting ATASLN from the throttle opening area AAM at the time of updating the learning value is obtained as an initial equivalent opening area AAI.

(3) The throttle opening at the intersection of the straight line and the curve drawn horizontally from the initial equivalent opening area AAI is determined as the initial equivalent throttle opening TVOI.

(4) The value obtained by subtracting TVOI from TVOM is the throttle opening corresponding to the throttle opening area learning value ATASLN, which is obtained as the idle rotation learning opening TASDTVO.

(4) The final throttle opening command value is obtained by adding the idle rotation learning opening TDTVO obtained in this way to the above throttle opening basic value determined according to the accelerator opening and the number of revolutions.

Whereas the correction method using the learning value in the conventional apparatus moves the broken line characteristic upward in parallel as shown in the middle part of FIG. 5, the correction method using the learning value in the present embodiment is shown in the lower part of FIG. As described above, the dashed line characteristic is translated in the left direction. In other words, whereas the conventional device corrects the amount of air (that is, the opening area), the present embodiment corrects the throttle opening. Comparing the conventional apparatus with the present embodiment, it can be seen that in the present embodiment, the deviation from the flow rate in the initial state is suppressed even at a distance from the point A (learning point).

As described above, in the present embodiment, since the correction method based on the learning value is the throttle opening correction method, even if the throttle flow for the same throttle opening may become small due to accumulation of dirt on the throttle portion, the conventional method may be used. The deviation from the initial flow rate characteristic can be suppressed to a smaller value than the opening area correction method.

Here, the operation of the present embodiment will be described.

The difference from the prior application device is that there is a series of steps 1, 2, and 3 (in the prior application device, the determination of the steady state of step 1 is not performed, the determination of the learning permission condition of step 3 comes first, and then the step 2 is performed). Followed by a stoichiometric request). For this reason, according to the present invention, when the rotation fluctuation occurs in accordance with the switching to the homogeneous stoichiometric combustion, the above <1> does not hold (that is, it is not in a steady state), and the steps after step 2 are skipped (that is, step 2). Even if the learning permission condition is satisfied, the learning value is not updated.) Then, when the rotation fluctuation accompanying the switching has disappeared, the process proceeds to step 2 again, and if the learning permission condition is satisfied, the learning value is updated.

As described above, in the present invention, it is first determined whether the vehicle is in a steady state before checking whether the learning permission condition is satisfied, and a homogeneous stoichiometric request is issued when the vehicle is in the steady state, and thereafter, the learning permission condition is satisfied. Since it is determined whether or not the engine speed is in the range, the fluctuation value of the rotation accompanying the switching to the homogeneous stoichiometric combustion is not included in the learning value, whereby the learning variation can be reduced.

FIG. 6 shows a second embodiment, which corresponds to FIG. The same steps as those in FIG. 2 are denoted by the same step numbers.

部分 Mainly the differences from FIG. 2 will be described. In step 11, the idle opening learning value TVO2 is calculated. More specifically, the feedback control of the idle speed is obtained by feedback control of the idle speed in accordance with the difference between the actual speed NE and the target idle speed NSET. At the sampling timing, the average value of the predetermined number of feedback correction amounts is calculated, and a weighted average value of the average value and the idle opening learning value at the timing when the average value is calculated is calculated as a new idle opening learning value. Update as a value. This idle opening learning value TVO2 is also stored in a memory (for example, a flash memory) when the engine is stopped.

When ADDNE <GRNE, the process proceeds from step 5 to step 12, and the idle opening learning value TVO1 is obtained by renewing a value obtained by subtracting the offset amount TASOFS2 (constant value) from the idle opening learning value TVO2. Modify the value. When ADDNE ≧ GRNE, the process proceeds from step 5 to step 13, where the idle opening learning value is not corrected (TVO1 = TVO2).

In step 14, a value obtained by subtracting the set value TVOIDL from the idle opening learned value TVO1 is calculated as an idle rotation learning opening TDTVO2.

Since the required idle air amount with respect to the target idle speed NSET is known in advance, a value obtained by converting the required idle air amount into a throttle opening using a throttle opening-flow characteristic table is the above-mentioned set value TVOIDL. It is.

で も In the second embodiment, the same operation and effect as those in the first embodiment are produced. Further, the configuration of the second embodiment is simpler.

By the way, even in an engine in which the required idle air amount has converged, the judgment result as to whether the engine has not converged or has converged is lost when the engine is stopped, the battery is replaced, the control unit (engine control ECM) is replaced, and the like. After the occurrence of the situation, the idle air amount becomes insufficient due to the correction of the decrease in the learning value while it is determined again before the convergence. Therefore, the determination result is stored in, for example, a non-volatile memory (for example, a flash memory) so that the determination result such as before or after convergence is not lost. It is possible to prevent erroneous learning due to being performed.

It is a control system figure of a 1st embodiment. It is a flowchart for demonstrating calculation of idle rotation learning opening degree TDTVO. FIG. 9 is a characteristic diagram of a required idle air amount with respect to a rotation speed integrated value ADDNE. FIG. 9 is a characteristic diagram for explaining a procedure for converting a throttle opening area learning value ATASLN into a throttle opening. FIG. 9 is a characteristic diagram showing a change in a flow characteristic with respect to a throttle opening. It is a flowchart for demonstrating the calculation of the idle rotation learning opening degree TDTVO2 of 2nd Embodiment. It is a claim correspondence figure of the 1st invention.

Explanation of reference numerals

3 Throttle device 4 Fuel injection valve 11 Control unit

Claims (1)

A throttle valve driven by an actuator;
Means for calculating a throttle opening basic value that provides an engine torque steady value according to the accelerator opening and the engine speed;
Means for storing a learning value corresponding to a temporal change in the opening area of the throttle valve portion,
Means for calculating a feedback correction amount such that the idle speed matches the target idle speed,
Means for correcting the throttle opening basic value with the feedback correction amount and the learning value to obtain a throttle opening command value;
Means for giving the throttle opening command value to the actuator.
Means for switching the combustion mode between stratified combustion and homogeneous stoichiometric combustion in accordance with the operating conditions, and performing combustion control so as to be stratified combustion when idling;
Means for determining whether the vehicle is in a steady state;
Means for forcibly switching the combustion mode to the homogeneous stoichiometric combustion when it is determined that the combustion is in a steady state;
Means for updating the learning value based on the feedback correction amount when a learning permission condition is satisfied in a state where it is determined that the engine is in a steady state.

Images