JP2021152341A - Engine control device - Google Patents

Abstract

To suppress deterioration of flexibility of throttle opening control for torque control of an engine.SOLUTION: In an engine control system 22 that performs torque control of an engine 10 through operations of a throttle opening and ignition timing, a maximum load factor used for setting target torque that is a control target value of the torque control and a maximum opening load factor used for calculating a target opening that is a control target value of the throttle opening are determined as individual values calculated separately.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine control device that performs torque demand type torque control.

As seen in Patent Document 1, an engine control device that performs torque demand type torque control is known. In torque demand type engine torque control, the throttle opening is controlled in order to achieve the target torque, which is the target value of the engine torque set based on the accelerator pedal operation amount, engine speed, and vehicle running conditions. To be told. Specifically, the load factor of the engine required to achieve the target torque is calculated as the value of the required load factor, and the throttle opening is controlled to the opening degree at which the load factor corresponding to the value of the required load factor can be obtained. .. The actual torque of the engine and the target torque deviate from each other during the intake response delay period from when the throttle opening is changed until the load factor changes to a value corresponding to the changed opening. Therefore, in the torque demand type torque control, the deviation of the actual torque from the target torque is suppressed by adjusting the torque according to the ignition timing etc. according to the deviation between the actual load factor obtained from the air flow meter output and the required load factor. There is.

The maximum load factor, which is the load factor when the throttle opening is set to the maximum opening which is the maximum value of the control range, is a value that changes depending on the engine speed. Therefore, in the current operating state, the maximum torque, which is the maximum value in the range of engine torque that can be adjusted by controlling the throttle opening, also becomes a value that changes depending on the engine speed. Even if a value exceeding the maximum torque is set as the target torque, it cannot be realized. Therefore, in the torque demand type torque control, the maximum load factor at the current engine speed is obtained, and the upper limit guard of the target torque is performed so that the value is equal to or less than the maximum torque obtained from the maximum load factor.

Japanese Unexamined Patent Publication No. 2009-185665

By the way, when controlling the throttle opening degree, the following values are set as the target opening degree value which is the control target value of the throttle opening degree. That is, when the required load factor is equal to or greater than the maximum load factor, the maximum opening degree is set as the value of the target opening degree. If the required load factor is less than the maximum load factor, the required load starts from the maximum opening, which is the value when the required load factor is the maximum load factor when the required load factor decreases from the maximum load factor. The target opening is set as a value that decreases as the rate decreases.

On the other hand, when looking only at the control of the throttle opening, it is desirable to set a value different from the actual maximum value of the load factor at the current engine speed as the maximum load factor used for calculating the target opening. In some cases. For example, if the target opening is calculated using a value smaller than the actual value as the value of the maximum load factor, the required load factor for which the maximum opening is set as the target opening is smaller than the actual maximum load factor. Become. In such a case, when the accelerator pedal is depressed to accelerate the vehicle, the throttle opening reaches the maximum opening from an earlier stage, so that the response of the vehicle at the time of acceleration is improved. However, if a value different from the actual value is set as the value of the maximum load factor, the torque control of the engine cannot be properly performed.

An engine control device that solves the above problems uses the throttle opening, which is the opening of the throttle valve installed in the intake passage of the engine mounted on the vehicle, and the operating amount of the engine other than the throttle opening to determine the engine torque. The engine torque is controlled by operating to set the target torque, which is the control target value of the engine torque. Then, the engine control device performs a maximum load factor calculation process for calculating the maximum load factor, which is the maximum value of the load factor of the engine at the current engine speed, and a process for setting a target torque according to the running condition of the vehicle. Therefore, based on the above maximum load factor, a target torque setting process that sets the target torque value so that the load factor becomes a value equal to or less than the maximum load factor, and a load factor request according to the target torque and the engine speed. Based on the required load factor calculation process that calculates the required load factor, which is a value, the maximum opening load factor calculation process that calculates the maximum opening load factor based on the engine speed, and the required load factor and the maximum opening load factor. , It is a process to calculate the target opening which is the control target value of the throttle opening, and when the required load factor is equal to or more than the maximum opening load factor, the maximum opening which is the maximum value of the control range of the throttle opening is set. Calculated as the value of the target opening, and when the required load factor is less than the maximum opening load factor, the required load factor becomes the maximum opening when the required load factor decreases from the maximum opening load factor. Target opening calculation processing that calculates the target opening as a value that decreases as the required load factor decreases from the maximum opening that is the value when the load factor is used, and throttle so that the throttle opening becomes the target opening. The throttle operation process that drives the valve is performed.

The maximum load factor when the engine speed is constant is achieved when the throttle opening is the maximum opening. Further, in the engine control device, when the required load factor is equal to or greater than the maximum opening load factor, the maximum opening is calculated as the value of the target opening. Therefore, the maximum load factor and the maximum opening load factor are essentially the same value.

On the other hand, the control characteristics of the throttle valve can be adjusted by appropriately changing the value of the maximum opening load factor used for calculating the target opening. At this time, in the engine control device, the maximum load factor used for setting the target torque in the torque control and the maximum opening load factor used for calculating the target opening degree in the throttle opening degree control are separately calculated. It is an individual value. Therefore, the control characteristic of the throttle valve can be adjusted by changing the value of the maximum opening load factor without affecting the setting of the target torque in the torque control. Therefore, according to the engine control device, a decrease in the degree of freedom in throttle opening control for engine torque control can be suppressed.

In the maximum load factor calculation process in the engine control device, the maximum load factor is calculated using a maximum load factor calculation map in which information about the relationship between the maximum load factor and the engine speed is stored in advance stored in the control device. It can be a process to be calculated. Similarly, the maximum opening load factor is also maximized using the maximum opening load factor calculation map that stores information about the relationship between the maximum opening load factor and the engine speed, which is stored in advance in the control device. It is possible to perform the process of calculating the load factor. However, in such a case, as described below, there is a risk that the operation of setting the calculation map at the time of designing the engine control device becomes complicated. For example, there may be a range of engine speeds for which a common map value is set for both the maximum load factor calculation map and the maximum opening load factor calculation map. When the map value of the maximum load factor calculation map in such a common range is corrected, it is necessary to correct the same map value for the maximum opening load factor calculation map. On the other hand, when setting the calculation map, the map values may be manually corrected many times, and there is a risk that the map values of both calculation maps will be inconsistent due to forgetting to correct or erroneously correcting the map values.

To this end, the engine control device contains a maximum load factor calculation map that stores information about the relationship between the maximum load factor and the engine speed, and a load factor that is the difference between the maximum load factor and the maximum opening load factor. A correction value calculation map in which information about the relationship between the correction value and the engine speed is stored is stored in advance. Then, the maximum load factor calculation process is the process of calculating the maximum load factor using the maximum load factor calculation map, and the maximum opening load factor calculation process is the maximum load calculated using the maximum load factor calculation map. It is preferable to perform the process of calculating the maximum opening load factor by correcting the rate with the load factor correction value calculated using the correction value calculation map. In such a case, in the part where "0" is set as the map value of the correction value calculation map, the maximum opening load factor is the maximum load factor no matter how many times the map value of the maximum load factor calculation map of that part is corrected. It will be the same value. Therefore, when correcting the map value of the maximum load factor calculation map in the above common portion, it is not necessary to correct the correction value calculation map. As described above, if the maximum opening load factor is calculated in the above embodiment, the operation of setting the calculation map at the time of designing the engine control device becomes easy.

By the way, in the large opening region near the maximum opening, the change in the load factor with respect to the change in the throttle opening becomes small, and the throttle opening is repeatedly changed significantly with respect to the minute change in the required load factor, so-called throttle hunting. May occur. The occurrence of throttle hunting in such a large opening region can be suppressed by performing the target opening calculation processing in the engine control device in the following manner.

Here, the ratio of the intake pressure after passing the throttle valve to the intake pressure before passing the throttle valve is defined as the throttle front-rear pressure ratio RP, and the throttle opening when the throttle front-rear pressure ratio RP becomes the default value RPwot is the switching point. The opening TAwot is set, the load factor KL when the throttle front-rear pressure ratio RP is the default value RPwot is set as the switching point load factor KLwot, and the throttle front-rear pressure ratio RP required to set the load factor as the required load factor is the required pressure. The ratio is RP *. At this time, the target opening degree calculation process in the engine control device is performed to target the throttle opening degree at which the throttle front-rear pressure ratio RP becomes the required pressure ratio RP * when the required pressure ratio RP * becomes a value equal to or less than the default value RPwot. Calculated as the opening value, and if the required pressure ratio RP * exceeds the default value RPwott, the switching point opening TAwot, switching point load factor KLwot, maximum opening TAmax, maximum opening load factor KLmax2, And the value "TA *" that satisfies the relationship of the equation (1) with respect to the required load ratio KL * is calculated as the value of the target opening degree.

上記目標開度演算処理では、要求圧力比ＲＰ＊が既定値ＲＰｗｏｔ以下の場合には、スロットル前後圧力比ＲＰが要求圧力比ＲＰ＊となるスロットル開度ＴＡが目標開度ＴＡ＊の値として演算される。要求圧力比ＲＰ＊が既定値ＲＰｗｏｔを超える場合にも、スロットル前後圧力比ＲＰが要求圧力比ＲＰ＊となるスロットル開度ＴＡが目標開度ＴＡ＊の値として演算すると、目標開度ＴＡ＊が最大開度ＴＡｍａｘに近づくにつれて、負荷率ＫＬに対する目標開度ＴＡ＊の感度が高くなる。そのため、大開度領域では、要求負荷率ＫＬ＊の僅かな変化に対して目標開度ＴＡ＊の値が大きく変化することになり、スロットルハンチングが発生してしまう。

In the above target opening calculation process, when the required pressure ratio RP * is equal to or less than the default value RPwot, the throttle opening TA at which the throttle front-rear pressure ratio RP becomes the required pressure ratio RP * is calculated as the value of the target opening TA *. Will be done. Even when the required pressure ratio RP * exceeds the default value RPwot, if the throttle opening TA at which the throttle front-rear pressure ratio RP becomes the required pressure ratio RP * is calculated as the value of the target opening TA *, the target opening TA * will be calculated. As the maximum opening TAmax approaches, the sensitivity of the target opening TA * to the load factor KL increases. Therefore, in the large opening region, the value of the target opening TA * changes significantly with respect to a slight change in the required load factor KL *, and throttle hunting occurs.

On the other hand, in the above target opening calculation process, when the required pressure ratio RP * exceeds the default value RPwot, the value of the target opening TA * is calculated so as to have a linear relationship with the required load factor KL *. Will be done. In such a case, in the region where the required pressure ratio RP * exceeds the default value RPwot, the rate of change of the target opening TA * with respect to the required load factor KL * is constant, so that throttle hunting is less likely to occur.

Moreover, since the target opening TA * is calculated as a value that changes in conjunction with the required load factor KL * even in the large opening region, gases other than fresh air such as recirculated exhaust, fuel vapor, and blow-by gas are emitted into the combustion chamber. It is possible to control the throttle opening TA so that the load factor KL changes according to the change in the required load factor KL * even in the situation where the gas flows into the gas. If the target opening degree calculation process is performed in this manner, the controllability of the throttle valve in the large opening degree region can be improved.

The figure which shows typically the structure of one Embodiment of an engine control device. A flowchart of the torque control routine executed by the engine control device. Maximum load factor A graph showing the relationship between the maximum load factor stored in the calculation map and the engine speed. A graph showing the relationship between the throttle front-rear pressure ratio and the throttle passing flow rate. A graph showing the relationship between the throttle front-rear pressure ratio and the Φ value. The graph which shows the relationship between the saturation flow rate and the throttle opening. A graph showing the relationship between the throttle opening and the throttle front-rear pressure ratio. The flowchart of the throttle opening control routine executed by the engine control device. A graph showing the relationship between the load factor correction value stored in the correction value calculation map and the engine speed. A graph showing the relationship between the maximum load factor, the maximum opening load factor, and the engine speed. The figure which shows the calculation mode of the target opening degree in a large opening degree region. A graph showing the relationship between the required load factor and the target opening in a large opening range.

Hereinafter, an embodiment of the engine control device will be described in detail with reference to FIGS. 1 to 12. The engine control device of the present embodiment is applied to a naturally aspirated engine mounted on a vehicle. The output of the engine is transmitted to the wheels as a driving force for traveling via a transmission.

As shown in FIG. 1, the engine 10 to which the present embodiment is applied includes an intake passage 12 through which the intake air flowing into the combustion chamber 11 flows and an exhaust passage 13 through which the exhaust gas discharged from the combustion chamber 11 flows. It is provided. Further, the engine 10 has an intake valve 14 that communicates / shuts off the intake passage 12 to the combustion chamber 11 according to valve opening / closing, and an exhaust passage 13 that communicates / shuts off the exhaust passage 13 to the combustion chamber 11 according to valve opening / closing. An exhaust valve 15 for shutting off is provided.

The intake passage 12 is provided with an air cleaner 16 for filtering dust and the like in the intake passage, and an air flow meter 17 for detecting the intake flow rate GA, which is the flow rate of the intake air flowing through the intake passage 12. Further, a throttle valve 18 is installed in a portion of the intake passage 12 on the downstream side of the air flow meter 17. The throttle valve 18 is installed in the intake passage 12 in a state in which the throttle valve 18 is rotatably supported by the shaft. The throttle valve 18 is rotationally driven by the throttle motor 19. Further, an injector 20 that injects fuel during intake is installed in a portion of the intake passage 12 on the downstream side of the throttle valve 18. An ignition device 21 is installed in the combustion chamber 11 to ignite a mixture of the intake air flowing in through the intake passage 12 and the fuel injected by the injector 20.

In such an engine 10, the throttle valve 18 serves as a valve for adjusting the throttle passing flow rate, which is the flow rate of the intake air passing through the throttle valve 18, by changing the opening area according to the rotation position in the intake passage 12. There is. The throttle opening TA in the following description represents the rotation angle of the throttle valve 18 from the fully closed position, which is the rotation position where the opening area becomes “0”.

The engine 10 configured as described above is controlled by an engine control system 22 as an engine control device. The engine control system 22 is configured as an electronic control unit including an arithmetic processing circuit that executes various arithmetic processing related to engine control and a memory in which programs and data are stored. In the engine control system 22, in addition to the above-mentioned detection signal of the intake flow rate GA by the air flow meter 17, detection signals such as the accelerator pedal operation amount ACC, the atmospheric pressure PA, and the throttle opening TA, which are the amount of depression of the accelerator pedal of the driver, are detected. Has been entered. Further, a pulsed crank signal CRNK output according to the rotation of the crankshaft 23 is input to the engine control system 22. The engine control system 22 obtains the engine speed NE from the crank signal CRNK.

In addition to the engine control system 22, various control systems are installed in the vehicle. For example, a shift control system that controls the shift of the transmission, an autocruise control system that controls the autocruise of the vehicle, a trunktion control system that controls the trunking to prevent the wheels from slipping, and the attitude of the vehicle when turning. It is a control system such as a running stability control system that performs running stability control for stabilization. In the following description, a control system other than the engine control system 22 installed in the vehicle will be referred to as another control system 30. The other control system 30 sets the required value of the engine torque in each control and outputs the required value to the engine control system 22. In the following description, the required values of the engine torque set by each of the other control systems 30 are described as the other required torques Ter1, Ter2, ....

The engine control system 22 controls the torque of the engine 10 through the driver required torque calculation process F1, the maximum load factor calculation process F2, the target torque setting process F3, the throttle opening control process F4, and the ignition timing control process F5. ing. The driver required torque calculation process F1 is a process for calculating the driver required torque Ted, which is a required value of the engine torque of the driver, based on the accelerator pedal operation amount ACC and the engine speed NE. The maximum load factor calculation process F2 is a process for calculating the maximum load factor KLmax1 which is the maximum value of the load factor KL of the engine 10 at the current engine speed NE, and the target torque setting process F3 is a control target value of the engine torque. This is a process for setting the target torque TE *. Further, the throttle opening control process F4 is a process of controlling the throttle opening TA of the throttle valve 18 according to the target torque TE *, and the ignition timing control process F5 is the ignition timing of the ignition device 21 according to the target torque TE *. This is a process for controlling SA.

Further, the engine control system 22 performs the throttle opening control process F4 through each of the required load factor calculation process F6, the maximum opening load factor calculation process F7, the target opening calculation process F8, and the throttle operation process F9. .. The required load factor calculation process F6 is a process for calculating the required load factor KL *, which is a required value of the load factor KL, based on the target torque TE * and the engine speed NE, and the maximum opening load factor calculation process F7 is the engine rotation. This is a process for calculating the maximum opening load factor KLmax2 based on the number NE. The target opening degree calculation process F8 is a process of calculating the target opening degree TA *, which is a control target value of the throttle opening degree TA, based on the required load factor KL * and the maximum opening degree load factor KLmax2. Then, the throttle operation process F9 is a process of driving the throttle valve 18 so that the throttle opening TA is set to the target opening TA *.

Next, the details of the torque control of such an engine 10 will be described. FIG. 2 shows a flowchart of a torque control routine executed by the engine control system 22 for torque control. During the operation of the engine 10 of the engine control system 22, the processing of this routine is repeatedly executed at a predetermined control cycle.

When the processing of this routine is started, first, in step S100, the driver required torque TED is calculated based on the accelerator pedal operation amount ACC and the engine speed NE. The driver required torque Ted indicates the engine torque required to meet the driver's demand for the driving force of the vehicle.

In the next step S110, other required torques Ter1, Ter2, ... Set by the other control system 30 are read. Then, in step S120, the required torque that should be given the highest priority in the current running condition of the vehicle from the driver required torque Ted and the other required torques Ter1, Ter2, ... Is set as the value of the final required torque Ter. ..

In the following step S130, the value of the maximum load factor KLmax1, which is the maximum value of the load factor KL of the engine 10 at the current engine speed NE, is calculated. The load factor KL determines the amount of intake air flowing into the cylinder, which is the mass of the intake air flowing into the combustion chamber 11, in the standard atmospheric condition occupying the stroke volume of the cylinder, that is, standard atmospheric pressure: 1013 hPa, standard air temperature: 20 ° C., standard relative humidity: It is expressed as a ratio to the mass of intake air of 60%. That is, the load factor KL represents the filling efficiency ηc of the intake air in the combustion chamber 11. The maximum load factor KLmax1 indicates the value of the load factor KL when the throttle opening TA is set to the maximum opening TAmax, which is the maximum value of the control range, at the current engine speed NE. The calculation of the maximum load factor KLmax1 is performed using the maximum load factor calculation map MAP1 stored in advance in the memory of the engine control system 22. The maximum load factor calculation map MAP1 stores information on the relationship between the engine speed NE and the maximum load factor KLmax1 obtained in advance by a test or the like. FIG. 3 shows the relationship between the engine speed NE and the maximum load factor KLmax1 in the maximum load factor calculation map MAP1 used in the engine control device of the present embodiment.

Subsequently, in step S140, the maximum torque TEmax, which is the engine torque when the load factor KL of the engine 10 is set to the maximum load factor KLmax1 at the current engine speed NE, based on the maximum load factor KLmax1 and the engine speed NE. The value is calculated. Then, in the subsequent step S150, the smaller value of the final required torque Ter and the maximum torque TEmax is set as the value of the target torque TE *.

In the next step S160, the throttle opening control process F4 for operating the throttle opening TA of the throttle valve 18 is performed according to the target torque TE *. Further, in the following step S170, the ignition timing control process F5 for operating the ignition timing SA of the ignition device 21 is performed according to the target torque TE *.

In such a torque control routine, the required torque that should be given the highest priority in the current running condition of the vehicle is set as the value of the final required torque Ter from among the driver required torque Ted and other required torques Ter1, Ter2, .... On the other hand, the values of the other required torques Ter1, Ter2, ... Are set according to the respective circumstances of the other control system 30, and therefore exceed the maximum torque TEmax of the engine 10 at the current engine speed NE, which is an unrealizable value. May be set. Therefore, in the torque control routine, the maximum load factor KLmax1 at the current engine speed NE is obtained, and the value of the target opening TA * is set to be equal to or less than the maximum torque TEmax obtained from the maximum load factor KLmax1. Is set.

Before the change in the throttle opening TA is reflected in the engine torque, there is a delay corresponding to the movement time of the intake air from the throttle valve 18 to the combustion chamber 11. Therefore, it may not be possible to achieve the engine torque equal to the target torque TA * only by controlling the throttle opening TA. Therefore, in the present embodiment, in the throttle opening control, the engine torque is brought closer to the target torque TE * within the range possible by operating the throttle opening TA, and the ignition timing is determined by the excess or deficiency caused by the delay due to the movement time of the intake air. By supplementing the ignition timing SA in control, the engine torque equal to the target torque TE * is achieved.

The processing of step S100 in such a torque control routine is the driver required torque calculation processing F1, the processing of step S130 is the maximum load factor calculation processing F2, and the processing of steps S110, step S120, step S140, and step S150 is the target torque. Each corresponds to the setting process F3.

Subsequently, the details of the throttle opening degree control process F4 in step S160 of the torque control routine will be described. Here, first, the basic logic for calculating the target opening TA *, which is the control target value of the throttle opening TA, will be described.

When calculating the target opening TA *, the engine control system 22 first calculates the required load factor KL *, which is the required value of the load factor KL, based on the target torque TE * and the engine speed NE. Here, the load factor KL that makes the engine torque a value close to the target torque TE * within a feasible range in consideration of the delay due to the movement time of the intake air is calculated as the value of the required load factor KL *.

On the other hand, the cylinder inflow intake amount is determined by the throttle downstream pressure PM, which is the intake pressure of the portion downstream of the throttle valve 18 in the intake passage 12, and the engine speed NE. Therefore, based on the required load factor KL * and the engine speed NE, the value of the throttle downstream pressure PM required to obtain the load factor KL for the required load factor KL * can be obtained. The engine control system 22 calculates the throttle downstream pressure PM at which the load factor KL for the required load factor KL * is obtained as the value of the required throttle downstream pressure PM * based on the required load factor KL * and the engine speed NE. There is.

Here, the mass flow rate of the intake air that passes through the throttle valve 18 and is distributed and supplied to the combustion chamber 11 of each cylinder of the engine 10 is defined as the intake valve passing flow rate. Since the inflow of intake air into the combustion chamber 11 is performed intermittently according to the opening and closing of the intake valve 14, the actual flow rate passing through the intake valve becomes a value that fluctuates according to the rotation of the engine 10. The value obtained by averaging the fluctuations is used as the flow rate through the intake valve. The number of intake strokes performed in the engine 10 during one rotation of the engine 10 is a number determined by the number of cylinders of the engine 10. Therefore, the engine speed NE, which is the number of revolutions of the engine 10 per unit time, is a value proportional to the number of intake strokes performed in the unit time in the engine 10, and the engine speed NE is multiplied by the required load factor KL *. The product (= NE × KL *) is a value proportional to the flow rate through the intake valve from which the load factor KL corresponding to the required load factor KL * is obtained.

In this embodiment, [rpm ·%] is used as a unit of the flow rate of the intake air used for calculating the target opening TA *. When the same unit is used, the intake valve passing flow rate [rpm ·%] is a value that matches the product of the engine speed NE [rpm] multiplied by the required load factor KL * [%].

The flow rate through the intake valve in a steady state in which the throttle opening TA and the engine speed NE are kept constant is equal to the flow rate through the throttle, which is the flow rate of the intake air passing through the throttle valve 18. Therefore, the throttle opening TA * at which the throttle downstream pressure PM becomes the required throttle downstream pressure PM * and the throttle passing flow rate is the product of the engine rotation speed NE and the required load factor KL * is set as the target opening TA * of the throttle valve 18. Then, the load factor KL for the required load factor KL * can be obtained.

The throttle passing flow rate is the product of the speed of intake air passing through the throttle valve 18 and the opening area of the throttle valve 18. The opening area of the throttle valve 18 is a function of the throttle opening TA. Further, the speed of intake air passing through the throttle valve 18 is determined by the throttle front-rear pressure ratio RP, which is the ratio of the throttle downstream pressure PM to the throttle upstream pressure PAC. The throttle upstream pressure PAC represents the intake pressure of the portion of the intake passage 12 on the upstream side of the throttle valve 18. In this embodiment, the atmospheric pressure PA is used as the throttle upstream pressure PAC. The range in which the value of the throttle front-rear pressure ratio RP can be taken is the range from "0" to "1". Therefore, if two of the three values of the throttle opening TA, the throttle front-rear pressure ratio RP, and the throttle passing flow rate are determined, the remaining one value is naturally determined.

FIG. 4 shows the relationship between the throttle opening TA, the throttle front-rear pressure ratio RP, and the throttle passing flow rate. The speed of intake air passing through the throttle valve 18 is "0" when the throttle front-rear pressure ratio RP is "1", and becomes a sound velocity when the throttle front-rear pressure ratio RP is a certain value α or less. The speed of intake air passing through the throttle valve 18 when the throttle front-rear pressure ratio RP is gradually increased from “α” to “1” is the value when the throttle front-rear pressure ratio RP is “α”. The pressure gradually decreases from the speed of sound to "0", which is the value when the throttle front-rear pressure ratio RP is "1". Further, the throttle passing flow rate is the product of the speed of the intake air passing through the throttle valve 18 and the opening area of the throttle valve 18. Therefore, when the throttle front-rear pressure ratio RP is constant, the larger the throttle opening TA, the larger the throttle passing flow rate. Therefore, the tendency of the throttle passing flow rate to change with respect to the throttle opening TA and the throttle front-rear pressure ratio RP is as shown in FIG.

Here, the throttle passing flow rate is defined as a throttle passing flow rate in a region where the throttle front-rear pressure ratio RP is “α” or less, that is, in a sound velocity range where the speed of intake air passing through the throttle valve 18 is sound velocity or higher. The saturated flow rate is the product of the opening area of the throttle valve 18 and the speed of sound, and the value is a function of the throttle opening TA. The ratio of the throttle passing flow rate to the saturated flow rate is defined as the Φ value. Since the speed of intake air passing through the throttle valve 18 is determined by the throttle front-rear pressure ratio RP, the Φ value is a function of the throttle front-rear pressure ratio RP. The Φ value also represents the ratio of the speed of the intake air passing through the throttle valve 18 to the speed of sound.

FIG. 5 shows the relationship between the Φ value and the throttle front-rear pressure ratio RP. As shown in the figure, the Φ value in the sound velocity range where the throttle front-rear pressure ratio RP is “α” or less is “1”. Further, when the throttle front-rear pressure ratio RP is "1", the Φ value is "0". The Φ value when the throttle front-rear pressure ratio RP is gradually increased from “α” to “1” is the value when the throttle front-rear pressure ratio RP is “α” from “1” before and after the throttle. The value gradually decreases to "0", which is the value when the pressure ratio RP is "1". In the memory of the engine control system 22, a Φ value calculation map MAP2 in which information about the relationship between the Φ value and the throttle front-rear pressure ratio RP is stored is stored in advance.

FIG. 6 shows the relationship between the saturated flow rate and the throttle opening TA. As described above, the saturated flow rate is proportional to the opening area of the throttle valve 18. Since the relationship between the throttle opening TA and the opening area is determined by the dimensions and shape of the intake passage 12 and the throttle valve 18, the relationship between the saturated flow rate and the throttle opening TA is obtained from their design specifications. There is. In the memory of the engine control system 22, an opening calculation map MAP3 in which information about the relationship between the saturated flow rate and the throttle opening TA is stored is stored in advance.

The throttle passing flow rate can be obtained as the product of the saturated flow rate at the current throttle opening TA and the Φ value at the current throttle front-rear pressure ratio RP. On the other hand, as described above, the required throttle downstream pressure PM * is obtained as the value of the throttle downstream pressure PM from which the load factor KL corresponding to the required load factor KL * can be obtained. Therefore, if the current throttle upstream pressure PAC is known, it is a throttle front-rear pressure ratio RP that can obtain a load factor KL equal to the required load factor KL * as the ratio of the required throttle downstream pressure PM * to the throttle upstream pressure PAC. The value of the required pressure ratio RP * can be obtained. Incidentally, in the naturally aspirated engine 10, the throttle upstream pressure PAC can be regarded as having the same pressure as the atmospheric pressure PA. Therefore, in the present embodiment, the quotient (= PM * / PA) obtained by dividing the required throttle downstream pressure PM * by the atmospheric pressure PA is obtained as the value of the required pressure ratio RP *.

Further, as described above, the intake valve passing flow rate at which the load factor KL for the required load factor KL * is obtained is the product of the required load factor KL * multiplied by the engine speed NE. Further, in the steady state, the flow rate passing through the intake valve and the flow rate passing through the throttle are equal to each other. Therefore, the value of the target opening degree TA * required to obtain the load factor KL for the required load factor KL * can be calculated by the following procedure.

As described above, the required throttle downstream pressure PM * represents the throttle downstream pressure PM when the flow rate passing through the intake valve becomes the flow rate at which the load factor KL equal to the required load factor KL * can be obtained. Therefore, the value of the required pressure ratio RP *, which is the ratio of the required throttle downstream pressure PM * to the throttle upstream pressure PAC, is when the flow rate passing through the intake valve becomes the flow rate at which the load factor KL equal to the required load factor KL * can be obtained. It represents the throttle front-rear pressure ratio RP. Therefore, based on the relationship of FIG. 5, the value of the Φ value when the throttle front-rear pressure ratio RP is the required pressure ratio RP * is obtained, and the load factor for the required load factor KL * is obtained from the obtained Φ value value. Calculate the quotient obtained by dividing the intake valve passing flow rate required to obtain KL. The value of this quotient represents the saturated flow rate at the throttle opening TA at which the load factor KL equal to the required load factor KL * is obtained, that is, at the target opening TA *. Therefore, based on the relationship of FIG. 6, if the throttle opening TA at which the quotient value is the saturated flow rate is obtained as the value of the target opening TA *, the throttle opening is obtained to obtain the load factor KL for the required load factor KL *. TA can be calculated as the value of the target opening TA *.

However, when the opening degree of the throttle valve 18 is controlled based on the target opening degree TA * calculated in this way, the following problem may occur.
FIG. 7 shows changes in the throttle front-rear pressure ratio RP when the throttle opening TA is changed in a state where the throttle upstream pressure PAC and the engine speed NE are constant. When the throttle opening TA is increased from "0" to the maximum opening TAmax, the throttle front-rear pressure ratio RP starts from "0", which is the value when the throttle opening TA is "0". The TA increases to "1", which is the value when the maximum opening TAmax is reached. However, when the throttle opening TA approaches the maximum opening TAmax, the rate of change of the throttle front-rear pressure ratio RP with respect to the throttle opening TA, that is, the ratio of the change amount of the throttle front-rear pressure ratio RP to the change amount of the throttle opening TA gradually increases. It becomes smaller. Therefore, in the large opening region where the throttle front-rear pressure ratio RP is close to "1", the sensitivity of the throttle front-rear pressure ratio RP to the throttle opening TA becomes low. That is, the value of the target opening degree TA * changes significantly with respect to a slight change in the required load factor KL *. As a result, in the large opening region, the throttle opening TA is frequently changed, that is, so-called throttle hunting occurs, and the load on the throttle motor 19 and the like may increase.

Further, when the accelerator pedal is depressed to accelerate the vehicle, it is required to rapidly increase the amount of intake air taken into the cylinder. On the other hand, in the calculation of the target opening TA * by the above basic logic, the maximum opening TAmax is the target opening TA * unless the accelerator pedal is depressed until the required load factor KL * reaches the maximum load factor KLmax1. Since it is not set as a value, the increase in the cylinder inflow intake amount when the vehicle is accelerating is delayed.

Based on the above, in the present embodiment, the throttle opening TA is controlled in the following modes.
FIG. 8 shows a flowchart of a throttle opening control routine executed by the engine control system 22 of the present embodiment when controlling the throttle opening TA. The engine control system 22 controls the throttle opening TA in step S160 of the torque control routine through the processing of this routine.

When the processing of this routine is started, first, in step S200, the value of the required load factor KL *, which is the required value of the load factor KL, is calculated based on the target torque TE * and the engine speed NE. Subsequently, in step S210, the required throttle downstream pressure PM * is calculated from the required load factor KL * and the engine speed NE. Further, in the next step S220, the quotient obtained by dividing the required throttle downstream pressure PM * by the throttle upstream pressure PAC is calculated as the value of the required pressure ratio RP *. In the present embodiment applied to the naturally aspirated engine 10 as described above, the atmospheric pressure PA is used as the throttle upstream pressure PAC. When applied to a supercharged engine, the detected value or estimated value of the supercharging pressure may be used as the value of the throttle upstream pressure PAC.

Subsequently, in step S230, it is determined whether or not the required pressure ratio RP * is a value larger than the default value RPwot. As the default value RPwot, a value smaller than the lower limit of the throttle front-rear pressure range in which throttle hunting may occur is set (see FIG. 7). If the required pressure ratio RP * at this time is a value equal to or less than the default value RPwot (S230: NO), the process proceeds to step S240. On the other hand, when the required pressure ratio RP * is a value larger than the default value RPwot (S230: YES), the process proceeds to step S300.

When the required pressure ratio RP * is equal to or less than the default value RPwot and the process proceeds to step S240, in that step S240, the throttle front-rear pressure ratio RP is set to the required pressure ratio RP * by using the above-mentioned Φ value calculation map MAP2. The value of the Φ value at a certain time is obtained as the value of the required Φ value PHY *. Further, in step S240, the quotient obtained by dividing the product of the required load factor KL * and the engine speed NE by the required Φ value PHY * is calculated as the value of the required saturated flow rate BPM *. Subsequently, in step S250, the throttle opening TA at which the saturated flow rate is the required saturated flow rate BPM * is calculated as the value of the target opening TA * using the opening calculation map MAP3 described above, and then the process is performed in step S260. It can be advanced. As described above, when the required pressure ratio RP * is equal to or less than the default value RPwot, the target opening degree TA * is calculated according to the above-mentioned basic logic.

Then, when the process proceeds to step S260, the process of this routine ends after the drive control of the throttle valve 18 is performed in order to set the throttle opening TA to the target opening TA * in the step S260. Will be done. The drive control of the throttle valve 18 is performed, for example, by feedback-adjusting the drive current of the throttle motor 19 according to the deviation of the throttle opening TA with respect to the target opening TA *.

On the other hand, when the required pressure ratio RP * is a value larger than the default value RPwot (S230: YES) and the process proceeds to step S300, the following two values are calculated in step S300. First, using the Φ value calculation map MAP2, the value of the Φ value when the throttle front-rear pressure ratio RP is the default value RPwot is calculated as the value of the switching point Φ value PHYwatt. Further, the quotient obtained by dividing the product obtained by multiplying the required load factor KL * by the engine speed NE by the switching point Φ value PHYwatt is calculated as the value of the switching point saturation flow rate BPMwatch.

Subsequently, in step S310, using the opening degree calculation map MAP3, the throttle opening TA at which the saturated flow rate becomes the switching point saturated flow rate BPMwot is calculated as the value of the switching point opening degree TAwot.

Further in step S320, the value of the load factor KL at which the throttle front-rear pressure ratio RP becomes the default value RPwott is calculated as the value of the switching point load factor KLwott. In calculating the switching point load factor KLwott, first, the product of the throttle upstream pressure PAC multiplied by the default value RPwott is obtained as the value of the switching point throttle downstream pressure PMwott. On the other hand, in the memory of the engine control system 22, a load factor calculation map MAP4 in which information about the relationship between the throttle downstream pressure PM, the engine rotation speed NE, and the load factor KL is stored is stored in advance. The value of the switching point load factor KLwot is calculated by using this load factor calculation map MAP4 to obtain the load factor KL at which the throttle downstream pressure PM becomes the switching point throttle downstream pressure PMwott at the current engine speed NE. There is. The value of the switching point load factor KLwot calculated in this way indicates the load factor KL when the throttle opening TA is set to the switching point opening TAwot without changing the control state of the engine 10 other than the throttle opening TA. ing.

By the way, in an engine equipped with a variable valve mechanism that changes the valve timing of the intake valve 14 such as valve timing and valve lift amount, the relationship between the throttle downstream pressure PM and engine rotation speed NE and the load factor KL as described above. Changes even when the valve operating characteristics of the intake valve 14 are changed by the variable valve timing mechanism. If the change in valve characteristics of the intake valve 14 by such a variable valve mechanism has a large effect on the load factor KL, the throttle downstream pressure PM, engine speed NE, and the operating amount and load factor KL of the variable valve mechanism The load factor calculation map MAP4 is configured so as to memorize the relationship with. Then, using the load factor calculation map MAP4, the switching point load factor KLwott may be calculated from the current engine speed NE, the operation amount of the variable valve mechanism, and the switching point throttle downstream pressure PMwott.

Subsequently, in step S330, the value of the maximum load factor KLmax1, which is the maximum value of the load factor KL of the engine 10 at the current engine speed NE, calculated in step S130 of the torque control routine described above is read. Further, in the next step S340, the value of the load factor correction value CKM, which is the difference between the maximum load factor KLmax1 and the maximum opening load factor KLmax2 described later, is obtained based on the engine speed NE. The load factor correction value CKM is calculated using the correction value calculation map MAP5 stored in advance in the memory of the engine control system 22. The correction value calculation map MAP5 stores information about the relationship between the engine speed NE and the load factor correction value CKM.

FIG. 9 shows the relationship between the engine speed NE and the load factor correction value CKM in the correction value calculation map MAP5. As shown in the figure, a positive value exceeds "N2" in the range of engine speed NE less than "N1", and a negative value exceeds "N2" in the range of engine speed NE from "N1" to "N2". In the range of engine speed NE, "0" is set as the value of the load factor correction value CKM. The range of the engine speed NE less than "N1" is the range of the engine speed NE in which the sensitivity of the throttle front-rear pressure ratio RP to the throttle opening TA in the large opening region is particularly low and throttle hunting is likely to occur. ing. Further, the range of the engine speed NE from "N1" to "N2" is the range of the engine speed NE in which a rapid increase in the cylinder inflow intake amount at the time of acceleration is particularly required in order to secure the acceleration performance of the vehicle. It has become.

Subsequently, in step S350, the sum of the maximum load factor KLmax1 plus the load factor correction value CKM is obtained as the value of the maximum opening load factor KLmax2. The maximum opening load factor KLmax2 indicates the minimum value in the range of the required load factor KL * with the target opening TA * as the maximum opening TAmax in the current engine speed NE.

FIG. 10 shows the relationship between the maximum load factor KLmax1 and the maximum opening load factor KLmax2 and the engine speed NE. As described above, the maximum load factor KLmax1 is the maximum value of the load factor KL at the current engine speed NE, and is used for setting the target torque TE * in torque control. On the other hand, as described above, the maximum opening load factor KLmax2 is the minimum value in the range of the required load factor KL * with the target opening TA * as the maximum opening TAmax. When the engine speed NE is constant, the load factor KL becomes maximum when the throttle opening TA is set to the maximum opening TAmax. Therefore, the maximum opening load factor KLmax2 should be originally the same value as the maximum load factor KLmax1. It is a parameter. However, in the present embodiment, different values are set for the maximum load factor KLmax1 and the maximum opening load factor KLmax2 depending on the engine speed NE. The reason for this will be described later.

Then, in step S360, as a value satisfying the relationship shown in the equation (2) based on the switching point opening TAwatt, the maximum opening TAmax, the required load factor KL *, the switching point load factor KLwot, and the maximum opening load factor KLmax2. The value of the target opening TA * is calculated. Then, in step S360, the upper limit guard process of the target opening TA * is performed so that the value is equal to or less than the maximum opening TAmax, and then the process proceeds to step S260. In the upper limit guard process, the value of the target opening TA * is maintained as it is when the target opening TA * is equal to or less than the maximum opening TAmax, and the maximum when the target opening TA * exceeds the maximum opening TAmax. The opening TAmax is reset as the value of the target opening TA *. Then, in step S260, after the drive control of the throttle valve 18 for driving the throttle valve 18 based on the target opening degree TA * set through step S360 is performed, the processing of this routine is completed.

なお、こうしたスロットル開度制御ルーチンにおけるステップＳ２００の処理が要求負荷率演算処理Ｆ６に、ステップＳ３２０〜ステップＳ３４０の処理が最大開度負荷率演算処理Ｆ７に、ステップＳ２６０の処理がスロットル操作処理Ｆ９に、それぞれ対応している。また、スロットル開度制御ルーチンにおける、残りの処理、すなわちステップＳ２１０〜２５０、ステップＳ３００〜Ｓ３２０、及びステップＳ３６０の処理が目標開度演算処理Ｆ８に対応している。

The process of step S200 in the throttle opening control routine is the required load factor calculation process F6, the processes of steps S320 to S340 are the maximum opening load factor calculation process F7, and the process of step S260 is the throttle operation process F9. , Each corresponds. Further, the remaining processes in the throttle opening degree control routine, that is, the processes of steps S210 to 250, steps S300 to S320, and steps S360 correspond to the target opening degree calculation process F8.

FIG. 11 shows a plot of each parameter of the equation (2) in a Cartesian coordinate system with the throttle opening TA and the load factor KL as coordinate axes. The line segment LAB shown in the figure has a coordinate point A in which the throttle opening TA is the switching point opening TAwot and the load factor KL is the switching point load factor KLwot, and the throttle opening TA is the maximum opening TAmax. Moreover, it is a line segment connecting the coordinate point B in which the load factor KL is the maximum opening load factor KLmax2. In step S360, the value of the throttle opening TA at the coordinate point C where the load factor KL is the required load factor KL * on the line segment LAB or on the extension line thereof is calculated as the value of the target opening TA *. That is, the equation (2) is an equation for calculating the target opening degree TA * through linear interpolation between the coordinate points A and B.

The operation and effect of this embodiment will be described.
In the present embodiment, the driver required torque Ted based on the accelerator pedal operation amount ACC and the other required torques Ter1, Ter2, ... Set by the other control system 30 should be given the highest priority in the current driving situation of the vehicle. The required torque is selected and the target torque TE * value is set. Then, the throttle opening TA and the ignition timing SA are controlled in order to realize the engine torque corresponding to the target torque TE *. At that time, the maximum load factor KLmax1 of the engine 10 at the current engine speed NE is calculated, and the upper limit reduction guard of the target torque TE * is performed so that the load factor KL becomes a value equal to or less than the maximum load factor KLmax1. An unrealizable value is not set as the target torque TE * value.

On the other hand, when controlling the throttle opening TA, the throttle opening TA required to realize the load factor KL for the required load factor KL * set according to the target torque TE * is the value of the target opening TA *. Calculate as. When calculating the target opening TA *, the throttle front-rear pressure ratio RP at which the load factor KL corresponding to the required load factor KL * is obtained is calculated as the value of the required pressure ratio RP *. When the required pressure ratio RP * is equal to or less than the default value RPwot, the throttle opening TA where the throttle front-rear pressure ratio RP becomes the required pressure ratio RP * based on the relationship between the throttle front-rear pressure ratio RP and the throttle opening TA. Is calculated as the value of the target opening TA *.

The curve L0 in FIG. 12 shows that even when the required pressure ratio RP * exceeds the default value RPwot, the throttle front-rear pressure ratio RP is the required pressure ratio RP, as in the case where the required pressure ratio RP * is less than or equal to the calculation switching pressure ratio RPwott. The relationship between the required load factor KL * and the target opening TA * when the throttle opening TA that is * is calculated as the value of the target opening TA * is shown. In such a case, as the required load factor KL * approaches the maximum load factor KLmax1, the ratio of the change amount of the target opening TA * to the change amount of the required load factor KL * is that is, the target opening degree with respect to the required load factor KL *. The sensitivity of TA * increases. Therefore, in the vicinity of the maximum opening TAmax, the value of the target opening TA * changes significantly with respect to a slight change in the required load factor KL *, and throttle hunting occurs.

On the other hand, the curve L1 of FIG. 12 shows the required load factor KL * in the large opening region when the same value as the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2 in the engine control device of the present embodiment. The relationship with the target opening TA * is shown. Further, the curve L2 in FIG. 12 shows the above relationship when a value K1 smaller than the maximum load factor KLmax1 is set as a value of the maximum opening load factor KLmax2 in the engine control device of the present embodiment. Further, the curve L3 of FIG. 12 shows the above relationship when a value K2 larger than the maximum load factor KLmax1 is set as a value of the maximum opening load factor KLmax2 in the engine control device of the present embodiment. In any case, the rate of change of the target opening TA * with respect to the required load factor KL * is constant in the large opening region from the switching point opening TAwatt to the maximum opening TAmax. Therefore, if a value such as the default value RPwot is appropriately set, the occurrence of throttle hunting in a large opening region can be suppressed.

When the value K1 smaller than the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2 as in the case of the curve L2 in FIG. 12, the required load factor smaller than the maximum load factor KLmax1 From KL *, the target opening TA * is set to the maximum opening TAmax. Therefore, in order to accelerate the vehicle, when the accelerator pedal is depressed, the throttle opening TA is opened to the maximum more quickly than when the same value as the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2. The degree will reach TAmax. Therefore, in the present embodiment, in the range of the engine speed NE where a rapid increase in the amount of air flowing into the cylinder is required during acceleration, a value smaller than the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2. ..

On the other hand, in the present embodiment, the sensitivity of the throttle front-rear pressure ratio RP to the throttle opening TA in the large opening region is particularly low, and in the range of the engine speed NE where throttle hunting is likely to occur, the case of the curve L3 in FIG. 12 As described above, a value K2 larger than the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2. In such a case, the ratio of the change amount of the target opening TA * to the change amount of the required load factor KL * in the range from the switching point load factor KLwot to the maximum load factor KLmax1 is the same value as the maximum load factor KLmax1. It is smaller than when it is set as the value of the rate KLmax2. Therefore, throttle hunting can be suppressed even in the engine speed NE range where the sensitivity of the throttle front-rear pressure ratio RP to the throttle opening TA is particularly low.

As described above, in the present embodiment, the control characteristics of the throttle valve 18 are adjusted by setting a value different from the actual maximum value of the load factor KL at the current engine speed NE as the value of the maximum opening load factor KLmax2. doing. On the other hand, if a value larger than the actual maximum value of the load factor KL at the current engine speed NE is set as the value of the maximum load factor KLmax1, the torque larger than the feasible engine torque is the target torque TE *. May be set as a value. As described above, it is necessary to set the actual maximum value of the load factor KL at the current engine speed NE as the value of the maximum load factor KLmax1 used for setting the target torque TE * in the torque control of the engine 10. In that respect, in the present embodiment, the maximum load factor KLmax1 is used in the torque control of the engine 10 as the value indicating the maximum value of the load factor KL at the current engine speed NE, while the maximum opening is used in the control of the throttle opening TA. The load factor KLmax2 is used. That is, in the present embodiment, in the torque control and the throttle opening TA control, separately calculated individual values are used as the maximum value of the load factor KL at the current engine speed NE. Therefore, the control characteristics of the throttle valve 18 can be adjusted without affecting the torque control.

In the present embodiment, the value of the maximum opening load factor KLmax2 is calculated by correcting the maximum load factor KLmax1 by the load factor correction value CKM calculated using the correction value calculation map MAP5. However, if a calculation map is prepared in which information about the relationship between the engine speed NE and the value of the maximum opening load factor KLmax2 is prepared, the maximum opening load factor KLmax2 can be obtained from the engine speed NE without following the above procedure. The value of can be calculated directly. However, in such a case, as described below, there is a risk that the operation of setting the calculation map at the time of designing the engine control device becomes complicated.

Here, the calculation map for directly calculating the maximum opening load factor KLmax2 from the engine speed NE as described above is referred to as the maximum opening load factor calculation map. As described above, in the present embodiment, in the range of the engine speed NE of "N2" or more, the same value as the value of the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2. In the following description, the range of the engine speed NE in which the same value as the maximum load factor KLmax1 is set as the value of the maximum opening load factor KLmax2 is described as a common range. Further, in the following description, the values of the maximum load factor KLmax1 and the maximum opening load factor KLmax2 for each engine speed NE in each calculation map are described as map values.

When calculating the maximum opening load factor KLmax2 using the maximum opening load factor calculation map as described above, when the map value of the maximum load factor calculation map MAP1 in the above common range is modified when designing the engine control device. It is necessary to correct the same map value in the maximum opening load factor calculation map. The control system of the engine 10 is a complicated system in which various elements are intertwined, and the modification may be repeated many times when setting the calculation map. Therefore, if the map value of the maximum opening load factor calculation map is also corrected each time the map value of the maximum load factor calculation map MAP1 is corrected, there is a risk that the map values of both calculation maps will be inconsistent due to erroneous correction or forgetting to correct. There is.

On the other hand, in the present embodiment, the maximum is obtained by using the correction value calculation map MAP5 that stores the relationship between the load factor correction value CKM, which is the difference between the maximum opening load factor KLmax2 and the maximum load factor KLmax1, and the engine speed NE. The opening load factor KLmax2 is calculated. In this case, for the part where "0" is set as the map value of the correction value calculation map MAP5, the same value as the maximum load factor KLmax1 is the maximum regardless of how the map value of the maximum load factor calculation map MAP1 is modified. It will be calculated as the value of the opening load factor KLmax2. Therefore, when modifying the map value of the maximum load factor calculation map MAP1 in the above common range, it is not necessary to modify the correction value calculation map MAP5. Further, even in the range of the engine speed NE other than the common range, even if only the map value of the maximum load factor calculation map MAP1 is modified while maintaining the map value of the correction value calculation map MAP5, the maximum load factor is KLmax1 and the maximum. The relative relationship with the opening load factor KLmax2 is maintained. Therefore, even in a range other than the common range, it may not be necessary to modify the correction value calculation map MAP5 according to the modification of the map value of the maximum load factor calculation map MAP1. As described above, if the maximum opening load factor KLmax2 is calculated using the correction value calculation map MAP5, the calculation map setting work at the time of designing the engine control device becomes easy.

According to the engine control device of the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment, the torque control and the throttle opening TA control use separately calculated individual values as the maximum value of the load factor KL at the current engine speed NE, and therefore the throttle valve. The influence of the adjustment of the control characteristics of 18 on the torque control can be suppressed.

(2) In the present embodiment, the maximum opening load factor KLmax2 is calculated using the correction value calculation map MAP5 that stores information about the difference from the maximum load factor KLmax1. Therefore, the operation of setting the calculation map at the time of design becomes easy.

(3) In the large opening region where the load factor KL exceeds the switching point load factor KLwot, the target is opened as a value satisfying the linear relationship with the required load factor KL * between the switching point opening TAwatt and the maximum opening TAmax. The degree TA * is calculated. Therefore, throttle hunting is less likely to occur in a large opening region. Moreover, since the target opening TA * is calculated as a value that changes in conjunction with the required load factor KL * even in the large opening region, gases other than fresh air such as recirculated exhaust, fuel vapor, and blow-by gas are emitted into the combustion chamber. It is possible to control the throttle opening TA so that the load factor KL changes according to the change in the required load factor KL * even in the situation where the gas flows into the gas. Therefore, the controllability of the throttle valve in the large opening region can be improved.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-The calculation of the target opening TA * using the maximum opening load factor KLmax2 may be performed in a mode different from that of the above embodiment. For example, the ratio of the required load factor KL * to the maximum opening load factor KLmax2 may be obtained, and the target opening TA * may be calculated using an calculation map that stores the relationship between the ratio and the target opening TA *. good.

-In the above embodiment, the maximum load factor KLmax1 calculated using the maximum load factor calculation map MAP1 is corrected by the load factor correction value CKM calculated using the correction value calculation map MAP5, whereby the maximum opening load factor KLmax2 Was calculated. The maximum opening load factor calculation map that stores information about the relationship between the maximum opening load factor KLmax2 and the engine speed NE as described above is stored in advance in the engine control system 22, and the maximum opening load factor is stored in advance. The maximum opening load factor KLmax2 may be calculated directly from the engine speed NE using the calculation map.

-In the above embodiment, the torque of the engine 10 is controlled through the operation of the throttle opening TA and the ignition timing SA. There are some engine operating amounts other than these that can adjust the engine torque by the operation. For example, in an engine provided with a variable valve mechanism that changes the valve characteristics of the intake valve 14 and the exhaust valve 15, the engine torque can be adjusted by manipulating the valve characteristics by the variable valve mechanism. Further, in an engine equipped with a variable capacity turbocharger, the engine torque can be adjusted by manipulating the capacity of the turbocharger. Even if the torque is controlled through the operation of the throttle opening TA and one or more engine operating amounts different from the throttle opening TA from the engine operating amount in which the engine torque can be adjusted. good.

-In each of the above embodiments, the case where the throttle control device is applied to the naturally aspirated engine 10 has been described, but if the supercharging pressure is used as the throttle upstream pressure PAC instead of the atmospheric pressure PA, the supercharging type It can also be applied to the engine of.

10 ... Engine 11 ... Combustion chamber 12 ... Intake passage 13 ... Exhaust passage 14 ... Intake valve 15 ... Exhaust valve 16 ... Air cleaner 17 ... Air flow meter 18 ... Throttle valve 19 ... Throttle motor 20 ... Injector 21 ... Ignition device 22 ... Engine control system 23 ... Crankshaft 30 ... Other control system

Claims (3)

The throttle opening, which is the opening of the throttle valve installed in the intake passage of the engine mounted on the vehicle, and the engine operating amount different from the same throttle opening, and the engine torque is the control target value of the same engine torque. In an engine control device that controls the torque of the engine by operating it to achieve the target torque.
Maximum load factor calculation processing that calculates the maximum load factor, which is the maximum value of the load factor of the engine at the current engine speed, and
It is a process of setting the target torque according to the traveling condition of the vehicle, and is a target of setting the target torque value so that the load factor becomes a value equal to or less than the maximum load factor based on the maximum load factor. Torque setting process and
A required load factor calculation process for calculating a required load factor, which is a required value of the load factor, according to the target torque and the engine speed.
Maximum opening load factor calculation processing that calculates the maximum opening load factor based on the engine speed, and
In the process of calculating the target opening degree, which is the control target value of the throttle opening degree, based on the required load factor and the maximum opening degree load factor, and the required load factor is equal to or greater than the maximum opening degree load factor. The maximum opening, which is the maximum value of the control range of the throttle opening, is calculated as the value of the target opening, and when the required load factor is less than the maximum opening load factor, the required load factor is used. Decreases from the maximum opening load factor, and decreases from the maximum opening, which is the value when the required load factor is the maximum opening load factor, as the required load factor decreases. Target opening calculation processing that calculates the target opening as a value, and
Throttle operation processing that drives the throttle valve so that the throttle opening becomes the target opening.
Engine control device to do. The engine control device includes a maximum load factor calculation map that stores information about the relationship between the maximum load factor and the engine speed, and a load factor correction that is the difference between the maximum load factor and the maximum opening load factor. A correction value calculation map in which information about the relationship between the value and the engine speed is stored is stored in advance.
The maximum load factor calculation process is a process for calculating the maximum load factor using the maximum load factor calculation map.
The maximum opening load factor calculation process is performed by correcting the maximum load factor calculated using the maximum load factor calculation map with the load factor correction value calculated using the correction value calculation map. The engine control device according to claim 1, which is a process for calculating the maximum opening load factor. The ratio of the intake pressure after the passage of the throttle valve to the intake pressure before the passage of the throttle valve is defined as the throttle front-rear pressure ratio RP, and the throttle opening when the throttle front-rear pressure ratio RP becomes the default value RPwot is the switching point. The throttle front-rear pressure required to set the opening TAwot, the load factor KL when the throttle front-rear pressure ratio RP becomes the default value RPwot, the switching point load factor KLwot, and the load factor the required load factor. When the ratio RP is the required pressure ratio RP *
The target opening degree calculation process sets the throttle opening degree at which the throttle front-rear pressure ratio RP becomes the required pressure ratio RP * when the required pressure ratio RP * becomes a value equal to or less than the predetermined value RPwot. When the required pressure ratio RP * exceeds the default value RPwott, the switching point opening TAwot, the switching point load factor KLwot, the maximum opening TAmax, and the maximum opening are calculated as the values of degrees. The engine control device according to claim 1 or 2, which is a process of calculating the load ratio KLmax2 and the value "TA *" satisfying the relationship of the following equation with respect to the required load ratio KL * as the value of the target opening degree.

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