JP2019203439A - Engine control device - Google Patents

Abstract

To make the control design of an engine control device easy.SOLUTION: An accelerator pedal opening ACC and requirement throttle downstream pressure PM* from an engine rotation number NE are calculated (S110), and a ratio of the requirement throttle downstream pressure PM* with respect to throttle upstream pressure (atmospheric pressure PA) is calculated as a value of a requirement pressure ratio PBYP (S120). Then, an opening being a value which is smaller than the other out of two values of an upper-limit pressure ratio RPMMAX and a requirement pressure ratio (mild change requirement pressure ratio PBYPSM) which are set by purge control 201 and a gear-change time torque-down control 202 as a target opening TA* of a throttle valve (S190 to S210).SELECTED DRAWING: Figure 6

Description

  The present invention relates to an engine control device.

  In a vehicle-mounted engine or the like, the amount of air flowing into the cylinder (in-cylinder air amount) is adjusted for each combustion through control of the throttle valve opening (throttle opening). For example, Patent Document 1 obtains a required throttle downstream pressure, which is a required value of an intake pressure after passing through a throttle valve (hereinafter, referred to as a throttle downstream pressure) from an accelerator pedal opening, and calculates a target from the required throttle downstream pressure. An engine control device that controls the opening of a throttle valve by determining the opening is described.

JP 2006-118373 A

  By the way, as a system mounted on a vehicle, there is a vapor processing system that releases and processes fuel vapor (vapor) in a fuel tank during intake. In the vapor processing system, the vapor is sucked and released into the intake air by the negative pressure generated by the throttle of the intake air at the throttle valve, and it is necessary to ensure the intake negative pressure above a certain level when performing the vapor purge. . Therefore, when the paper purge is executed, the opening at which the intake negative pressure becomes the minimum value necessary for the vapor purge is set as the upper limit of the throttle opening, and the throttle opening is set so that it falls within the upper limit. The control range may be limited. In addition, the occurrence of a shift shock may be suppressed by limiting the engine torque by limiting the control range of the throttle opening during the shift. As described above, there is a case where the control range of the throttle opening is limited in accordance with the operation state of the engine.

  When limiting the control range of the throttle opening, it is necessary to set an appropriate value according to the operating condition as the upper limit value of the control range of the throttle opening. However, since the relationship between the throttle opening and the intake flow state quantity such as intake flow rate and intake pressure differs for each engine model, the upper limit of the appropriate throttle opening according to the driving situation is also different for each engine model. Different values. For this reason, the upper limit value must be set in consideration of the above-mentioned relationship that differs for each model.

  The present invention has been made in view of such circumstances, and a problem to be solved is to facilitate control design of throttle valve opening control.

  An engine control apparatus that solves the above-described problems performs opening degree control of a throttle valve installed in an intake passage of the engine. Then, the engine control device performs a required throttle downstream pressure calculation process for calculating a required throttle downstream pressure that is a required value of the intake pressure after passing through the throttle valve from the accelerator pedal opening and the engine speed, and before passing through the throttle valve. A throttle upstream pressure acquisition process for acquiring a throttle upstream pressure that is an intake pressure of the engine, a required pressure ratio calculation process for calculating a ratio of the required throttle downstream pressure to the throttle upstream pressure as a value of the required pressure ratio, and an operating state of the engine An upper limit pressure ratio setting process that sets an upper limit pressure ratio according to the throttle upstream pressure, and a throttle front-rear pressure ratio that is a ratio of the intake pressure after passing through the throttle valve to the throttle upstream pressure is the required pressure ratio and the upper limit pressure ratio. The opening that is the smaller of the two values is calculated as the target opening of the throttle valve Is doing and ShimegiHirakudo arithmetic processing, the.

  In the engine control device configured as described above, the throttle valve is set so that the throttle front-rear pressure ratio, which is the pressure ratio of the intake air before and after passage through the throttle valve, becomes the smaller value of the required pressure ratio and the upper limit pressure ratio. The target opening degree can be calculated. That is, the control range of the throttle opening can be limited to a range in which the throttle front-rear pressure ratio is not more than the upper limit pressure ratio. The throttle front-rear pressure ratio is a universal physical quantity that does not vary depending on the engine model, and the upper limit is set to an appropriate value according to the operating condition of the engine without considering the difference in throttle valve characteristics for each engine model. A certain upper limit pressure ratio can be set. Therefore, the control design of the throttle valve opening control becomes easy.

  It should be noted that it is necessary to ensure a certain level of intake negative pressure when performing a vapor purge that releases the fuel vapor in the fuel tank into the intake air. The intake negative pressure can be ensured by setting a positive value less than 1 as the value of the upper limit pressure ratio when the vapor purge is performed in the upper limit pressure ratio setting process.

  In addition, in order to suppress a shock (shift shock) that occurs during a shift of a transmission connected to the engine, engine torque during a shift may be limited. The engine torque for suppressing such a shift shock is limited by setting a positive value less than 1 as the value of the upper limit pressure ratio when the transmission is being shifted in the upper limit pressure ratio setting process. It is possible.

  In a large opening range where the throttle opening is large, the sensitivity of the throttle front-rear pressure ratio with respect to the throttle opening, and thus the sensitivity of the flow rate through the throttle, becomes low, and throttle hunting in which significant changes in the throttle opening are frequently made is likely to occur. On the other hand, in the required pressure ratio calculation processing in the engine control device, when the ratio of the required throttle downstream pressure to the throttle upstream pressure is less than a predetermined value, the same ratio is directly calculated as the value of the required pressure ratio. When the ratio is equal to or greater than the predetermined value, a value obtained by performing a gradual change process for relaxing the change of the value with respect to the ratio may be calculated as the value of the required pressure ratio. In such a case, since the change of the target opening degree in the large opening degree region becomes gradual, throttle hunting hardly occurs.

  Further, in the target opening calculation process in the engine control device, when the value of the required pressure ratio exceeds the predetermined value, the throttle valve opening at which the throttle front-rear pressure ratio becomes the predetermined value; It is desirable to calculate the target opening by linearly interpolating the opening according to the throttle front-rear pressure ratio with respect to the maximum opening of the throttle valve. In such a case, the throttle opening degree TA can be increased to the maximum opening degree TAMAX while suppressing throttle hunting.

The schematic diagram of the structure of one Embodiment of an engine control apparatus. The graph which shows the relationship between throttle front-back pressure ratio, throttle opening, and throttle passage flow rate. The graph which shows the relationship between throttle front-back pressure ratio and (PHI) value. The graph which shows the relationship between throttle opening and saturation flow. The graph which shows the relationship between throttle opening and throttle front-back pressure ratio. The flowchart of target opening degree calculation routine. The figure which shows the calculation aspect of the target opening in the large opening area | region in a target opening calculation routine.

  Hereinafter, an embodiment of an engine control device will be described in detail with reference to FIGS. The engine control device of this embodiment is applied to a naturally aspirated engine mounted on a vehicle.

  As shown in FIG. 1, an engine 10 to which the present embodiment is applied includes an intake passage 12 through which intake air flowing into the combustion chamber 11 flows and an exhaust passage 13 through which exhaust exhausted from the combustion chamber 11 flows. Is provided. Further, the engine 10 has an intake valve 14 for communicating / blocking the intake passage 12 to / from the combustion chamber 11 in response to opening / closing of the valve, and an exhaust passage 13 in communication / to the combustion chamber 11 depending on opening / closing of the valve. And an exhaust valve 15 for blocking.

  The intake passage 12 is provided with an air cleaner 16 that filters dust and the like in the intake air, and an air flow meter 17 that detects the flow rate of intake air (intake flow rate GA) flowing through the intake passage 12. In addition, 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 while being rotatably supported by the shaft. The throttle valve 18 is rotationally driven by a throttle motor 19. Further, an injector 20 for injecting fuel during intake is installed in a portion of the intake passage 12 downstream of the throttle valve 18. The combustion chamber 11 is provided with an ignition plug 21 that ignites an air-fuel 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 is a valve that adjusts the flow rate of intake air (throttle passage flow rate) passing through the throttle valve 18 by changing the opening area according to the rotational position in the intake passage 12. Yes. In the following description, the throttle opening degree TA represents the rotation angle of the throttle valve 18 from the rotation position (fully closed position) where the opening area becomes zero.

  A crankshaft 23 that is an output shaft of the engine 10 is connected to wheels 25 via a transmission 24. Further, the engine 10 is provided with a vapor processing system that releases and processes fuel vapor (vapor) generated in the fuel tank 26 into the intake air. The vapor processing system includes a charcoal canister 27 that collects vapor in the fuel tank 26, a purge passage 28, and a purge valve 29. The purge passage 28 is a passage that connects the charcoal canister 27 and a portion of the intake passage 12 downstream of the throttle valve 18, and a purge valve 29 is provided in the middle thereof. The vapor collected in the charcoal canister 27 is discharged into the intake air in response to the opening of the purge valve 29.

  The engine 10 configured as described above is controlled by an engine control unit 22 as an engine control device. The engine control unit 22 includes an arithmetic processing circuit that executes various arithmetic processes related to engine control, and a memory that stores programs and data. In addition to the detection signal of the intake air flow rate GA by the air flow meter 17 described above, the engine control unit 22 includes the driver's accelerator pedal depression amount (accelerator pedal opening ACC), atmospheric pressure PA, and throttle valve 18 opening (throttle throttle). Detection signals such as the opening degree TA) are input. The engine control unit 22 is supplied with a pulsed crank signal CRNK output in accordance with the rotation of the crankshaft 23. The engine control unit 22 obtains the engine speed NE from the crank signal CRNK.

  The engine control unit 22 executes purge control, shift torque reduction control, and the like as part of engine control. The purge control is performed in order to discharge (purge) the vapor generated in the fuel tank 26 and collected in the charcoal canister 27 into the intake air. In the purge control, the purge valve 29 is opened when the vapor purge is executed. Then, the vapor collected into the intake passage 12 is sucked into the intake passage 12 through the purge passage 28 by the intake negative pressure generated by the throttle of the throttle valve 18, thereby performing the vapor purge into the intake air. Further, the torque reduction control during shifting restricts engine torque during shifting in order to suppress torque shock (shifting shock) accompanying the shifting of the transmission 24.

  The engine control unit 22 controls the opening degree of the throttle valve 18. When controlling the opening of the throttle valve 18, the engine control unit 22 first calculates a required load factor KL *, which is a required value of the load factor KL, based on the accelerator pedal opening ACC and the engine speed NE. The load factor KL represents the ratio [%] of the in-cylinder air amount to the maximum air amount. Note that the in-cylinder air amount is the mass of the intake air flowing into the combustion chamber 11 for each intake stroke, and the maximum air amount is the throttle opening TA at the current engine speed NE, which is the maximum value of the control range. The in-cylinder air amount when the degree is TAMAX is shown.

  The in-cylinder air amount is a value determined by the intake pressure in the portion of the intake passage 12 downstream of the throttle valve 18 (hereinafter referred to as the throttle downstream pressure PM) 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 necessary to obtain the load factor KL corresponding to the required load factor KL * can be obtained. Based on the required load factor KL * and the engine speed NE, the engine control unit 22 calculates the throttle downstream pressure PM that provides the load factor KL for the required load factor KL * as the value of the required throttle downstream pressure PM *. Yes.

  Here, the mass flow rate of the intake air that passes through the throttle valve 18 and is distributed and supplied to the combustion chambers 11 of the cylinders of the engine 10 is referred to as a valve passage flow rate. Note that since the intake air flows into the combustion chamber 11 intermittently according to the opening and closing of the intake valve 14, the actual valve passage flow rate varies depending on the rotation of the engine 10, but in the following description. The flow rate through the valve represents an average of these fluctuations. The number of intake strokes performed in the engine 10 during one revolution of the engine 10 is determined by the number of cylinders of the engine 10. Therefore, the engine speed NE, which is the engine speed per unit time, becomes 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 corresponding to the valve passage flow rate at which the load factor KL corresponding to the required load factor KL * is obtained.

  The valve passage flow rate in a steady state in which the throttle opening degree TA and the engine speed NE are kept constant is equal to the flow rate of the intake air passing through the throttle valve 18 (hereinafter referred to as the throttle passage flow rate). Accordingly, the throttle valve opening TA is set so that the throttle valve opening pressure TA becomes the required throttle downstream pressure PM *, and the throttle valve opening TA is obtained so that the throttle passage flow rate corresponding to the product obtained by multiplying the required load factor KL * by the engine speed NE is obtained. If the degree TA * is set, a load factor KL corresponding to the required load factor KL * can be obtained.

  The throttle passage 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. Further, the opening area of the throttle valve 18 is a function of the throttle opening degree TA. Further, the speed of the intake air passing through the throttle valve 18 is determined by the ratio of the throttle downstream pressure to the intake pressure (throttle upstream pressure) in the upstream portion of the throttle valve 18 in the intake passage 12 (hereinafter, the throttle front-rear pressure ratio). . The possible range of the throttle front-rear pressure ratio is a range from 0 to 1. Therefore, if two values are determined among the three values of the throttle opening degree TA, the throttle front / rear pressure ratio, and the throttle passage flow rate, the remaining one value is also determined automatically.

  FIG. 2 shows the relationship between the throttle opening degree TA, the throttle front-rear pressure ratio, and the throttle passage flow rate. Note that the speed of the intake air passing through the throttle valve 18 is 0 when the throttle front-rear pressure ratio is 1, and the speed of sound when the throttle front-rear pressure ratio is a certain value α or less. The speed of the intake air passing through the throttle valve 18 when the throttle front-rear pressure ratio is gradually increased from α to 1 is 1 from the sound speed at which the throttle front-rear pressure ratio is α. It gradually decreases to 0 which is the value at the time of. Further, as the throttle opening TA increases, the opening area of the throttle valve 18 also increases. Therefore, the changing tendency of the throttle passage flow rate with respect to the throttle opening degree TA and the throttle front-rear pressure ratio is as shown in FIG.

  Here, the throttle flow rate in a region where the throttle front-rear pressure ratio is α or less (sound velocity region) is defined as a saturation flow rate. The saturation 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 degree TA. The ratio of the flow rate through the throttle to the saturated flow rate is defined as the Φ value. Since the speed of the intake air passing through the throttle valve 18 is determined by the throttle front-rear pressure ratio, the Φ value is a function of the throttle front-rear pressure ratio. The Φ value also represents the ratio of the speed of intake air passing through the throttle valve 18 to the speed of sound.

  FIG. 3 shows the relationship between the Φ value and the throttle front-rear pressure ratio. As shown in the figure, the Φ value is 1 in the sound speed range where the throttle front-rear pressure ratio is α or less. The Φ value is 0 when the throttle front-rear pressure ratio is 1. The Φ value when the throttle front-rear pressure ratio is gradually increased from α to 1 is a value when the throttle front-rear pressure ratio is 1 from 1 when the throttle front-rear pressure ratio is α. The value gradually decreases to zero. The relationship between the Φ value and the throttle front-rear pressure ratio is stored in the memory of the engine control unit 22 as a Φ value calculation map MAP1.

  FIG. 4 shows the relationship between the saturation flow rate and the throttle opening degree TA. Since the relationship between the saturation flow rate and the throttle opening degree TA is determined by the size and shape of the intake passage 12 and the throttle valve 18, it can be obtained from their design specifications. The relationship between the saturation flow rate and the throttle opening degree TA is stored in the memory of the engine control unit 22 as an opening degree calculation map MAP2.

  The throttle passage flow rate can be obtained as a product obtained by multiplying the saturation flow rate at the current throttle opening TA by the Φ value at the current throttle front-rear pressure ratio. On the other hand, as described above, the required throttle downstream pressure PM * is obtained as a value of the throttle downstream pressure PM that provides a load factor KL corresponding to the required load factor KL *. Therefore, if the current throttle upstream pressure is known, the ratio of the throttle front-rear pressure (hereinafter referred to as the required pressure) that provides the load factor KL corresponding to the required load factor KL * as the ratio of the required throttle downstream pressure PM * to the throttle upstream pressure. The ratio PBYP). Incidentally, in the naturally aspirated engine 10, it can be considered that the throttle upstream pressure is the same pressure as the atmospheric pressure PA. Therefore, in this embodiment, a 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 PBYP.

  Furthermore, as described above, the valve passage flow rate at which the load factor KL corresponding to the required load factor KL * is obtained can be obtained as a product obtained by multiplying the required load factor KL * by the engine speed NE. In a steady state, the valve passage flow rate and the throttle passage flow rate are equal. Therefore, the value of the target opening degree TA * necessary for obtaining the load factor KL corresponding to 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 when the valve passage flow rate is a flow rate at which the load factor KL corresponding to the required load factor KL * is obtained. Therefore, the value of the required pressure ratio PBYP, which is the ratio of the required throttle downstream pressure PM * to the throttle upstream pressure (in this embodiment, the atmospheric pressure PA), is obtained as a load factor KL corresponding to the required load factor KL * for the valve passage flow rate. It represents the throttle front-rear pressure ratio when the flow rate becomes the desired flow rate. Therefore, based on the relationship of FIG. 3, the value of Φ value when the throttle front-rear pressure ratio is the required pressure ratio PBYP is obtained, and the load factor KL corresponding to the required load factor KL * is obtained from the obtained Φ value. The quotient obtained by dividing the flow rate through the valve necessary to obtain is calculated. The value of the quotient represents the throttle opening TA at which the load factor KL corresponding to the required load factor KL * is obtained, that is, the saturation flow rate at the target opening TA *. Therefore, based on the relationship of FIG. 4, if the throttle opening TA at which the value of the quotient becomes the saturation flow rate is obtained as the value of the target opening TA *, the throttle opening that provides the load factor KL corresponding to the required load factor KL *. TA can be calculated as the value of the target opening degree TA *.

However, when the opening degree control of the throttle valve 18 is performed based on the target opening degree TA * thus calculated, the following problem may occur.
FIG. 5 shows changes in the throttle front-rear pressure ratio when the throttle opening degree TA is changed in a state where the throttle upstream pressure (atmospheric pressure PA) 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 is from 0 when the throttle opening TA is 0 to when the throttle opening TA is the maximum opening TAMAX. It increases to 1 which is the value of. However, as the throttle opening degree TA increases, the change rate of the throttle front-rear pressure ratio with respect to the throttle opening degree TA (ratio of the change amount of the throttle front-rear pressure ratio with respect to the change amount of the throttle opening TA) gradually decreases. Therefore, in the large opening range where the throttle front-rear pressure ratio is close to 1, the sensitivity of the throttle front-rear pressure ratio with respect to the throttle opening TA is low. That is, the value of the target opening degree TA * greatly changes with a slight change in the required load factor KL *. As a result, in the large opening range, so-called throttle hunting, in which significant changes in the throttle opening TA are frequently performed, may occur, and a great load may be applied to the throttle motor 19 and the like. In the present embodiment, a predetermined constant (intake pressure saturation pressure ratio RPMWOT) is set as the lower limit value of the throttle front-rear pressure range in which such throttle hunting may occur.

  As described above, in the present embodiment, purge control and shift torque reduction control are performed as part of engine control. In the present embodiment, the control range of the throttle opening degree TA is limited during execution of such purge control and shift torque-down control.

  In the present embodiment, the target opening degree TA of the throttle valve 18 is controlled in the following manner in order to suppress the throttle hunting as described above, and to limit the control range of the throttle opening degree TA in the purge control and the torque down control at the time of shifting. * Is being calculated.

  FIG. 6 shows a flowchart of a target opening calculation routine executed by the engine control unit 22 for calculating the target opening TA *. The engine control unit 22 repeatedly executes the processing of this routine every predetermined control cycle while the engine is operating. The engine control unit 22 controls the opening degree of the throttle valve 18 by driving the throttle motor 19 so that the throttle opening degree TA approaches the target opening degree TA * calculated through execution of this routine.

  When the processing of this routine is started, first, in step S100, values of the accelerator pedal opening degree ACC, the engine speed NE, the atmospheric pressure PA, and the upper limit pressure ratio RPMMAX are acquired. The upper limit pressure ratio RPMMAX is set by the purge control 201 and the torque reduction control 202 during shifting. In the purge control 201, during execution of the vapor purge, the maximum value of the throttle front-rear pressure ratio that can secure the negative intake pressure necessary for the execution of the vapor purge is set as the value of the upper limit pressure ratio RPMMAX. Further, in the shift torque reduction control 202, the throttle front-rear pressure ratio at which the engine torque becomes the upper limit value capable of suppressing the shift shock during the shift of the transmission 24 is set as the value of the upper limit pressure ratio RPMMAX. In the purge control 201 and the shift torque reduction control 202, a value larger than the intake pressure saturation pressure ratio RPMWOT and less than 1 is set as the value of the upper limit pressure ratio RPMMAX. It should be noted that when the control range of the throttle opening degree TA is not limited in any of the purge control 201 and the shift torque reduction control 202, the upper limit value of the range in which the value of the throttle front-rear pressure ratio can be taken, or 1 A larger value is set as the value of the upper limit pressure ratio RPMMAX. Further, when both the purge control 201 and the torque reduction control 202 at the time of shifting simultaneously limit the control range of the throttle opening TA, among the values set by the purge control 201 and the values set by the torque reduction control 202 at the time of shifting The smaller value is set as the value of the upper limit pressure ratio RPMMAX. Thus, in the present embodiment, in the purge control 201 and the shift torque reduction control 202, the upper limit pressure ratio setting process for setting the upper limit pressure ratio RPMMAX according to the operating state of the engine 10 is performed.

  Subsequently, in step S110, the required load factor KL * and the required throttle downstream pressure PM * are calculated based on the accelerator pedal opening degree ACC and the engine speed NE. In the subsequent step S120, the quotient obtained by dividing the required throttle downstream pressure PM * by the throttle upstream pressure is calculated as the value of the required pressure ratio PBYP. In the present embodiment applied to the naturally aspirated engine 10, the required pressure ratio PBYP is calculated using the detected value of the atmospheric pressure PA as the value of the throttle upstream pressure. On the other hand, when applied to a supercharged engine, the required pressure ratio PBYP may be calculated using the detected value or estimated value of the supercharging pressure as the value of the throttle upstream pressure.

  Subsequently, in step S130, it is determined whether or not the required pressure ratio PBYP is larger than the above-described intake pressure saturation pressure ratio RPMWOT. If the required pressure ratio PBYP is equal to or less than the intake pressure saturation pressure ratio RPMWOT (NO), the process proceeds to step S140. On the other hand, when the required pressure ratio PBYP is larger than the intake pressure saturation pressure ratio RPMWOT (YES), the process proceeds to step S160.

  When the process proceeds to step S140, in step S140, using the above-described Φ value calculation map MAP1, the Φ value when the throttle front-rear pressure ratio is the required pressure ratio PBYP is the required Φ value PHYPM *. Calculated as a value. In step S140, the quotient obtained by dividing the product of the required load factor KL * and the engine speed NE by the required Φ value PHYPM * is calculated as the value of the required saturation flow rate BPM *. Subsequently, in step S150, the throttle opening degree TA at which the saturation flow rate becomes the required saturation flow rate BPM * is calculated as the value of the target opening degree TA * using the opening degree calculation map MAP2. Is terminated.

  On the other hand, if the process proceeds to step S160 as a result of the determination in step S130, the following two values are calculated in step S160. First, using the Φ value calculation map MAP1, the Φ value when the throttle front-rear pressure ratio is the intake pressure saturation pressure ratio RPMWOT is calculated as the intake pressure saturation Φ value PHYPMWOT. Then, the product obtained by multiplying the required load factor KL * by the engine speed NE and dividing by the intake pressure saturation Φ value PHYPMWOT is calculated as the value of the intake pressure saturation flow rate BPMWOT. In step S170, the opening degree calculation map MAP2 is used to calculate the throttle opening degree TA when the saturation flow rate is the intake pressure saturation flow rate BPMWOT as the value of the intake pressure saturation opening degree TAPWMOT.

  Subsequently, in step S180, a value obtained by subjecting the required pressure ratio PBYP to a gradual change process that reduces the change in value is calculated as the value of the gradual change required pressure ratio PBYPSM. In the present embodiment, the value of the slowly changing required pressure ratio PBYPSM is calculated by updating the value so as to satisfy the relationship of Expression (1). Note that S is a coefficient that determines the degree of slow change, and is set to a value larger than 1. The greater the value set for the coefficient S, the greater the degree of gradual change in the value of the gradual change required pressure ratio PBYPSM.

Next, in step S190, it is determined whether or not the slowly changing required pressure ratio PBYPSM is larger than the upper limit pressure ratio RPMMAX set by the purge control 201 or the torque reduction control 202 during shifting. Here, when the slowly changing required pressure ratio PBYPSM is larger than the upper limit pressure ratio RPMMAX (S190: YES), in step S200, the value of the upper limit pressure ratio RPMMAX is set as the value of the slowly changing required pressure ratio PBYPSM. After that, the process proceeds to step S210. On the other hand, when the slowly changing required pressure ratio PBYPSM is equal to or less than the upper limit pressure ratio RPMMAX (S190: NO), the process of step S200 is skipped and the process proceeds to step S210 as it is. That is, in step S190 and step S200, the upper limit guard process for the slowly changing required pressure ratio PBYPSM by the upper limit pressure ratio RPMMAX is performed.

  When the process proceeds to step S210, in step S210, the relationship of the expression (2) is satisfied based on the intake pressure saturation pressure ratio RPMWOT, the intake pressure saturation opening degree TAPMWOT, the maximum opening degree TAMAX, and the slowly changing required pressure ratio PBYPSM. After the value is calculated as the value of the target opening degree TA *, the process of this routine is terminated.

FIG. 7 shows the intake pressure saturation pressure ratio RPMWOT, the intake pressure saturation opening TAPMWOT, the maximum opening TAMAX, the slow change required pressure ratio PBYPSM, and the target opening in the orthogonal coordinate system with the throttle opening and the throttle front-rear pressure ratio as coordinate axes. The relationship of degree TA * is shown. Here, the coordinate point where the value of the throttle opening in the orthogonal coordinate system is X and the value of the throttle front-rear pressure ratio is Y is represented as (X, Y). The value of the target opening degree TA * at this time is expressed as follows: the throttle front-rear pressure ratio is a slowly changing required pressure ratio PBYPSM on the line LAB connecting the coordinate point A (TAPWMOT, RPMWOT) and the coordinate point B (TAMAX, 1). This is the value of the throttle opening at the coordinate point C. That is, the value of the target opening TA * at this time is calculated by linear interpolation of the throttle opening TA according to the throttle front-rear pressure ratio between the intake pressure saturation opening TAPMWOT and the maximum opening TAMAX.

The operation and effect of this embodiment will be described.
In step S110 in the target opening calculation routine, a required throttle downstream pressure PM * which is a required value of the intake pressure (throttle downstream pressure PM) after passing through the throttle valve 18 is calculated from the accelerator pedal opening ACC and the engine speed NE. Request throttle downstream pressure calculation processing is performed. In step S100, a throttle upstream pressure acquisition process is performed to acquire a throttle upstream pressure (atmospheric pressure PA) that is an intake pressure before passing through the throttle valve. In step S120, a request for the throttle upstream pressure (atmospheric pressure PA) is performed. A required pressure ratio calculation process for calculating the ratio of the throttle downstream pressure PM * as the value of the required pressure ratio PBYP is performed. Then, in the processing after step S130 in the target opening calculation routine, target opening calculation processing for calculating the target opening TA * of the throttle valve 18 is performed.

  On the other hand, in the present embodiment, in the purge control 201 and the torque reduction control 202 during shifting, an upper limit pressure ratio setting process for setting the upper limit pressure ratio RPMMAX according to the operating state of the engine 10 is performed. In the target opening degree calculation process, the required pressure ratio PBYP (in this embodiment, the required pressure ratio PBYP is a slow change required pressure ratio PBYPSM) and the upper limit pressure ratio RPMMAX, Based on the smaller value, the target opening degree TA * of the throttle valve 18 is calculated. As a result, when the vapor purge is executed, the intake negative pressure necessary for the execution is secured, and when the transmission 24 is changed, the control range of the throttle opening TA is limited so that the engine torque is limited to a range in which the shift shock can be suppressed. Is done.

  As described above, in the conventional engine control apparatus, the control range of the throttle opening TA in such a case is limited by setting the upper limit value of the throttle opening TA. However, the relationship between the opening degree of the throttle valve 18 and the intake flow state quantity such as the intake flow rate and the intake pressure is different for each engine model and has a non-linear relationship. For this reason, it is necessary to perform an adapting operation for individually obtaining an appropriate upper limit value of the throttle opening degree TA satisfying the demands for purge control and shift torque reduction control for each engine model. On the other hand, in the present embodiment, the upper limit pressure ratio RPMMAX is set, and the target opening degree TA * is set so that the throttle front-rear pressure ratio falls within the upper limit value or less. The control range of the throttle opening TA in the down control is limited. The throttle front / rear pressure ratio is a universal physical quantity that does not depend on the engine model. Therefore, the upper limit pressure ratio is set so that it meets the requirements for purge control and torque-down control during gear shifting, without performing the adaptation work for each model. RPMMAX can be set. Therefore, the control design of the opening degree control of the throttle valve 18 becomes easy.

  In the present embodiment, when the required pressure ratio PBYP is equal to or less than a predetermined value (intake pressure saturation pressure ratio RPMWOT) (S130: NO), the target opening degree TA * is calculated based on the required pressure ratio PBYP. On the other hand, when the required pressure ratio PBYP exceeds the intake pressure saturation pressure ratio RPMWOT (S130: YES), a value obtained by subjecting the required pressure ratio PBYP to a gradual change process for relaxing the change in value (slow change required pressure) The target opening degree TA * is calculated based on the ratio PBYPSM). Therefore, compared with the case where the target opening degree TA * is calculated based on the required pressure ratio PBYP even in the large opening region, the change in the target opening TA * with respect to the change in the required load factor KL * etc. in the large opening region becomes slow. Hunting is less likely to occur.

  The sensitivity of the throttle front-rear pressure ratio with respect to the throttle opening degree TA becomes smaller as the maximum opening degree TAMAX is approached. Therefore, even if the target opening degree TA * is calculated using the slowly changing required pressure ratio PBYPSM, throttle hunting may not be fully suppressed in the opening degree region near the maximum opening degree TAMAX. On the other hand, in this embodiment, when the value of the required pressure ratio PBYP exceeds the intake pressure saturation pressure ratio RPMWOT, the target opening degree TA * is calculated in the following manner. That is, in this case, the throttle opening according to the throttle front-rear pressure ratio between the throttle opening (intake pressure saturation opening TAPMWOT) at which the throttle front-rear pressure ratio becomes the intake pressure saturation pressure ratio RPMWOT and the maximum opening TAMAX. The target opening degree TA * is calculated by linear interpolation of degree TA. In such a case, in the region where the value of the required pressure ratio PBYP exceeds the intake pressure saturation pressure ratio RPMWOT, the rate of change of the target opening degree TA * with respect to the slowly changing required pressure ratio PBYPSM is constant. Therefore, the sensitivity of the throttle front-rear pressure ratio with respect to the throttle opening TA does not become so small even in the opening area near the maximum opening TAMAX. Therefore, in the engine control apparatus of the present embodiment, the upper limit of the control range of the throttle opening TA can be expanded to the maximum opening TAMAX while suppressing throttle hunting.

This embodiment can be implemented with the following modifications. The present embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.
In the above embodiment, when the required pressure ratio PBYP exceeds the intake pressure saturation pressure ratio RPMWOT, the throttle opening TA linear depending on the throttle front-rear pressure ratio between the intake pressure saturation opening TAPMWOT and the maximum opening TAMAX The target opening degree TA * was calculated by interpolation. The calculation of the target opening degree TA * in such a case may be performed in the same manner as in the case where the required pressure ratio PBYP is equal to or lower than the intake pressure saturation pressure ratio RPMWOT, instead of linear interpolation. That is, first, using the Φ value calculation map MAP1, the value of the Φ value when the throttle front-rear pressure ratio is the slowly changing required pressure ratio PBYPSM is obtained as the value of the required Φ value PHYPM *. Subsequently, a quotient obtained by dividing the product of the required load factor KL * and the engine speed NE by the value of the required Φ value PHYPM * is calculated as the value of the required saturation flow rate BPM *. Then, using the opening calculation map MAP2, the throttle opening TA at which the saturation flow becomes the required saturation flow BPM * is calculated as the value of the target opening TA *.

  In the above embodiment, the value of the upper limit pressure ratio RPMMAX is always set to a value larger than the intake pressure saturation pressure ratio RPMWOT. When a value smaller than the intake pressure saturation pressure ratio RPMWOT may be set as the value of the upper limit pressure ratio RPMMAX, the processing procedure of the target opening degree calculation routine may be changed as follows. That is, the calculation of the required Φ value PHYPM * in step S140 in the target opening calculation routine is performed based on the smaller value of the two values of the required pressure ratio PBYP and the upper limit pressure ratio RPMMAX.

  In the above embodiment, when the required pressure ratio PBYP is less than or equal to the intake pressure saturation pressure ratio RPMWOT, the target opening degree TA * is calculated based on the required pressure ratio PBYP, and the required pressure ratio PBYP exceeds the intake pressure saturation pressure ratio RPMWOT In this case, the target opening degree TA * is calculated based on the slowly changing required pressure ratio PBYPSM obtained by subjecting the required pressure ratio PBYP to the slowly changing process. If throttle hunting is not a problem, the target opening degree TA * may be calculated based on the required pressure ratio PBYP even when the required pressure ratio PBYP exceeds the intake pressure saturation pressure ratio RPMWOT.

  In the above embodiment, the control range of the throttle opening degree TA is limited based on the upper limit pressure ratio RPMMAX in two cases when the vapor purge is performed and when the transmission 24 is shifted. In other cases, the same restriction may be performed.

  In the above embodiment, by updating the value so as to satisfy the relationship of the expression (1), the value obtained by performing the slow change process for relaxing the change in the value on the required pressure ratio PBYP is the value of the slow change required pressure ratio PBYPSM. Was calculated as. As long as the change in value is calculated with respect to the required pressure ratio PBYP, the value of the slowly changing required pressure ratio PBYPSM may be calculated in other modes.

DESCRIPTION OF SYMBOLS 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 ... spark plug, 22 ... engine control unit, 23 ... crankshaft, 24 ... transmission, 25 ... wheel, 26 ... fuel tank, 27 ... charcoal canister, 28 ... purge passage, 29 ... purge valve.

Claims (5)

A device for controlling the opening of a throttle valve installed in an intake passage of an engine,
A required throttle downstream pressure calculation process for calculating a required throttle downstream pressure which is a required value of the intake pressure after passing through the throttle valve from the accelerator pedal opening and the engine speed;
A throttle upstream pressure acquisition process for acquiring a throttle upstream pressure that is an intake pressure before passing through the throttle valve;
A required pressure ratio calculation process for calculating a ratio of the required throttle downstream pressure to the throttle upstream pressure as a value of the required pressure ratio;
An upper limit pressure ratio setting process for setting an upper limit pressure ratio according to the operating condition of the engine;
The degree of opening at which the throttle front-rear pressure ratio, which is the ratio of the intake pressure after passing through the throttle valve to the throttle upstream pressure, is the smaller of the two values of the required pressure ratio and the upper limit pressure ratio A target opening calculation process for calculating as a target opening of the throttle valve;
An engine control device that performs. 2. The engine control device according to claim 1, wherein, in the upper limit pressure ratio setting process, a positive value less than 1 is set as the value of the upper limit pressure ratio when a vapor purge is performed to release fuel vapor in the fuel tank into the intake air. . 3. The upper limit pressure ratio setting process sets a positive value less than 1 as the value of the upper limit pressure ratio when a transmission connected to the engine is shifting. The engine control device described. While performing a gradual change process that calculates a value obtained by applying a gradual change process to the required pressure ratio to moderate the change in value as a value of the gradual change required pressure ratio,
In the target opening calculation process, when the value of the required pressure ratio is equal to or less than a predetermined value, the target opening is calculated using the required pressure ratio, and the value of the required pressure ratio exceeds the predetermined value. The engine control device according to claim 1, wherein the target opening is calculated using the slow change required pressure ratio. In the target opening calculation process, when the value of the required pressure ratio exceeds the predetermined value,
The target opening is obtained by linearly interpolating the opening according to the throttle front-rear pressure ratio between the throttle valve opening at which the throttle front-rear pressure ratio becomes the predetermined value and the maximum opening of the throttle valve. The engine control apparatus according to claim 4, wherein the degree is calculated.