Engine torque control method and engine torque control device

Abstract

To secure an intake amount with which a set torque profile can be actualized.SOLUTION: An engine torque control method that controls engine torque according to a first torque profile for suppressing a shock of a vehicle comprises: executing a first step of setting the first torque profile, a second step of setting a temporary slow torque profile, a third step of calculating a slow upper-limit torque profile for a case in which an air intake is controlled according to the temporary slow torque profile, and a fourth step of determining whether the slow upper-limit torque profile is equal to or larger than the first torque profile over the entire range; and then executing a fifth step of setting the temporary slow torque profile as a slow torque profile when the determination result of the fourth step is affirmative, or correcting the temporary slow torque profile until an affirmative determination result is obtained if the result is not affirmative and then repeating the second step to the fourth step.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an engine torque control method and an engine torque control device. [Background technology]

[0002] Patent Document 1 discloses a method of controlling engine torque when the vehicle's driving state changes with a change in accelerator operation amount, for example, when the accelerator pedal is depressed to switch from a coasting state (driven state) to an accelerating state (driving state). Specifically, when the accelerator pedal operation amount changes, a torque profile is set according to the driving state and the backlash state of the drive system gears, and the engine torque is controlled according to this torque profile, thereby suppressing shocks that occur in the vehicle with changes in driving state. The change in engine torque according to the torque profile is achieved by adjusting the ignition timing, which has excellent responsiveness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 038807 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because there are advance and retard limits for ignition timing, there is a limit to the region of engine torque that can be achieved by adjusting the ignition timing (torque realization region). For example, even if the ignition timing is advanced to the optimal ignition timing, the desired engine torque cannot be obtained if the intake air volume is insufficient. On the other hand, even if the ignition timing is retarded to the misfire limit, the engine torque cannot be suppressed to the desired value if the intake air volume is large. In other words, in order to control the engine torque according to the torque profile, it is necessary to match the torque realization region to the torque profile, and to do so, it is necessary to appropriately control the intake air volume.

[0005] Therefore, an object of the present invention is to control an intake device that controls the intake amount so that the torque realization region and the torque profile match. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an engine torque control method in which, when the driving state of a vehicle driven by an internal combustion engine changes according to an accelerator operation amount, a controller sets a first torque profile, which is a torque profile up to a target engine torque according to the accelerator operation amount, and controls the engine torque according to the first torque profile. In this method, the controller executes the following steps: a first step of setting the first torque profile, which is a torque profile that suppresses shocks that occur with changes in the driving state, a second step of setting a provisional slow torque profile, which is a provisional value of a slow torque profile, which is a profile of an engine torque used to control an intake device that adjusts the intake amount of the internal combustion engine, based on the accelerator operation amount, a third step of calculating a slow upper limit torque profile, which is a profile of an upper limit value of the engine torque that can be realized by ignition timing control when the intake amount is controlled according to the provisional slow torque profile, and a fourth step of comparing the slow upper limit torque profile with the first torque profile. Then, if the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range, a fifth step is executed in which the provisional slow torque profile is set as the slow torque profile, and if there is a region in which the slow upper limit torque profile is smaller than the first torque profile, the process returns to the second step in which a new provisional slow torque profile is set by correcting the provisional slow torque profile, and then the third and fourth steps are executed, and this process is repeated until the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range. Effect of the Invention

[0007] According to the above aspect, it is possible to control the intake device that controls the intake amount so that the torque realization region and the torque profile match. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a drive system of a vehicle. [Diagram 2] FIG. 2 is a time chart of engine torque when switching from a driven state to a driving state. [Diagram 3] FIG. 3 is a time chart for explaining a method of setting the slow torque profile in the first embodiment. [Figure 4] FIG. 4 is a flow chart showing a control routine for setting the slow torque profile. [Diagram 5] FIG. 5 is a time chart for explaining a method of setting the slow torque profile in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] [First embodiment] FIG. 1 is a schematic configuration diagram of a drive system of a vehicle 100 to which an embodiment of the present invention is applied.

[0011] The drive system of the vehicle 100 transmits drive torque generated in the internal combustion engine 1 to drive wheels 7 via an engine output shaft 1A, a torque converter 2, an automatic transmission 3, a transmission output shaft 4, a final drive 5, and a drive shaft 6. The final drive 5 includes a final gear in addition to a so-called differential gear.

[0012] The controller 10 controls the operation / stop and torque of the internal combustion engine 1, and the shifting and forward / reverse switching of the automatic transmission 3 based on the detection values ​​of sensors and an inhibitor switch (not shown). The sensors include, for example, a turbine rotating shaft rotation speed sensor that detects the turbine rotation speed of the torque converter 2, an output shaft rotation speed sensor that detects the rotation speed of the transmission output shaft (=vehicle speed), an ATF oil temperature sensor that detects the oil temperature of the automatic transmission 3, an accelerator pedal position sensor that detects the position of the accelerator pedal, etc. The inhibitor switch detects the range position selected by the select operation by the driver.

[0013] The controller 10 is composed of a microcomputer equipped with a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 10 may be composed of a plurality of microcomputers. The controller 10 of this embodiment includes an engine controller 9 that controls the internal combustion engine 1, and an AT controller 8 that controls the automatic transmission 3, and these are connected via a CAN communication line to exchange predetermined signals.

[0014] The automatic transmission 3 is a stepped automatic transmission that includes multiple planetary gear mechanisms and multiple friction elements, some of which function as engagement elements and others as release elements, and achieves multiple gear stages by combining engagement of the friction elements. Note that the specific configuration of the automatic transmission 3 and the engagement combinations for each gear stage can be known (for example, JP 2019-158086 A).

[0015] The AT controller 8 monitors changes in the driving point determined by the vehicle speed and the accelerator opening, and performs gear shift control based on this and a pre-stored gear shift map.

[0016] The engine controller 9 performs various controls of the internal combustion engine 1 alone, as well as torque control through cooperative control with the shift control. When the target torque of the internal combustion engine 1 changes, for example, when returning from a fuel cut state, the engine controller 9 executes preventive anti-jerk control (hereinafter also referred to as PAJ control) that limits the engine torque to a value lower than the target torque determined by the accelerator opening and the vehicle speed. This PAJ control is intended to suppress torsional vibrations (hereinafter also referred to as torsional vibrations) of a rotating shaft of the power transmission system (for example, a rotating shaft of a differential gear, a final gear, etc.). Torsional vibrations are generated when the engine torque and the reaction force of the drive system against the engine torque act alternately on the rotating shaft, and cause longitudinal vibrations of the vehicle. Specifically, the PAJ control changes the engine torque to a torque profile that limits the engine torque to a value lower than the target torque by retarding the ignition timing in accordance with the vibration period of the torsional vibrations.

[0017] FIG. 2 is a time chart of the torque transmitted to the automatic transmission 3 when the PAJ control is executed when switching from the driven state to the driving state. The engine torque in the driven state is the coast torque Te0 (negative value), and the target engine torque according to the accelerator pedal depression amount is Te λ Let us assume that.

[0018] In this embodiment, the driven state is assumed to be a so-called coasting state, which includes both cases where fuel cut is performed and cases where it is not performed.

[0019] The solid line in the figure is the engine torque profile under PAJ control (hereinafter referred to as the first torque profile), the dashed line in the figure is the required torque according to the accelerator pedal depression amount, and the dashed line in the figure shows the torsional vibration of the rotating shaft of the drive train gear.

[0020] In this embodiment, the engine torque is increased from the timing t1 when the engine torque starts to increase in response to the accelerator being depressed, so that the engine torque is increased to the target engine torque Te λThe period from the first phase Ph1 to the fourth phase Ph4 is divided into four phases, until timing t5 when the torque reaches the first phase Ph1, and the engine torque is controlled.

[0021] The first phase Ph1 is from time t1 to time t2 when the torsion of the drive gear rotating shaft caused by the engine torque (hereinafter also referred to as coasting torque) Te0 during coasting disappears. In other words, during the first phase Ph1, backlash is eliminated in the direction in which the coasting torque Te0 acts (hereinafter also referred to as the deceleration direction). The direction opposite to the deceleration direction is referred to as the acceleration direction.

[0022] The second phase Ph2 is from time t2 to time t3 when the backlash in the acceleration direction is eliminated. In other words, during the second phase, the drive gears rotate without contacting each other (hereinafter, this state is also referred to as a free running state).

[0023] The third phase Ph3 is from the timing t3 to the timing t4 after a predetermined time has elapsed. The predetermined time will be described later. The fourth phase Ph4 is from the timing t4 until the engine torque reaches the target engine torque Te λ That is, during the periods of the third phase Ph3 and the fourth phase Ph4, torsional vibration occurs in the rotating shaft of the drive system gear.

[0024] As described above, the clearance elimination period is divided into two phases, the first phase Ph1 and the second phase Ph2, and after the clearance elimination period ends, the engine torque reaches the target engine torque Te λ The process of reaching this milestone is divided into two phases: the third phase (Ph3) and the fourth phase (Ph4).

[0025] Next, the profile of each phase will be described.

[0026] (Phase 1) The torque profile of the first phase Ph1, that is, the coast torque Te0 at the timing t1 to the torque Te at the timing t2, 01 The torque profile up to (the engine torque at which the torsion of the rotating shaft of the drive gear disappears) is assumed to have undergone first-order lag filtering. Specifically, it is expressed by equation (1).

[0027] Te = ζ{1-e (-ωa·t)}+Te0···(1)

[0028] In formula (1), ωa is a value determined according to factors such as the gear ratio of the transmission, the vehicle weight, and the drive torque. t is the time elapsed from timing t1, and the coast torque Te0 is determined from the friction torque of the internal combustion engine 1, the auxiliary load torque, and the like. In this way, the engine torque increased in the first phase Ph1 is set based on the coast torque Te0, which is the engine torque in the driven state. In addition, in the first phase Ph1, the larger the coast torque Te0 is, the larger the engine torque increased in the first phase Ph1 is.

[0029] In equation (1), ζ is the torque Te ζ is obtained by subtracting the coast torque Te0 from the torque Te ζ is the torque Te 01 Torque Te ζ is a value determined according to factors such as the gear ratio of the transmission, the vehicle weight, and the driving torque.

[0030] In other words, in equation (1), the initial value is the coast torque Te0, and the target value is the torque Te ζ The torque profile is as follows: 01 Not torque Te ζ The reason for using the torque Te 01 If the target value is set to Te, the torque Te 01 This is because, although it approaches, it never reaches Te ζ is determined according to the time from timing t1 to timing t2, the angular velocity at that time, and other requirements. ζThe larger the torque profile, the closer it becomes to a straight line, and the smaller the torque profile, the more curved the profile becomes.

[0031] The reason for setting the torque profile as above is to control the rotation speed when the first phase Ph1 enters the second phase Ph2. In equation (1), Te is the torque Te 01 The timing at which this occurs is timing t2 at which the first phase Ph1 ends.

[0032] (Phase 2) The torque profile in the second phase Ph2, i.e., the torque Te at the timing t2 01 Torque Te at timing t3 02 The torque profile up to (the torque at the moment the backlash in the acceleration direction is eliminated) is expressed by equation (2). In equation (2), b is the gradient of the engine torque, that is, the amount of change per unit time, and is a value determined according to factors such as the gear ratio of the transmission, the vehicle weight, and the drive torque. t is the time elapsed from timing t2.

[0033] Te = b t + Te 01 (2)

[0034] The reason for setting such a torque profile is to suppress the change in rotation speed in the idle state. In equation (2), the time t when Te becomes the torque Te02 is the end timing t3 of the second phase Ph2. In addition, the increase in engine torque per unit time in the second phase Ph2 is set smaller than that in the first phase Ph1. In addition, the engine torque increased in the second phase Ph2 is set independently of the coast torque Te0, which is the engine torque in the driven state. In other words, there is no correlation between the engine torque increased in the second phase Ph2 and the coast torque Te0.

[0035] (Phase 3) In the third phase, the engine torque is Te 02Immediately after the backlash is eliminated, the vehicle will initially tilt forward due to its longitudinal vibration, so during this time the engine torque is maintained to suppress the longitudinal vibration of the vehicle. The time from timing t3 to timing t4 in the third phase Ph3 is half the period of the longitudinal vibration of the vehicle, and the period of the longitudinal vibration of the vehicle is determined according to the gear ratio of the transmission, etc.

[0036] (Phase 4) The torque profile in the fourth phase Ph4, i.e., the torque Te at timing t4 02 Torque Te at timing t5 λ The torque profile up to the target engine torque is processed by a first-order lag filter. Specifically, it is expressed by the formula (3).

[0037] Te = λ{1-e (-ωc·t)}+Te 02 (3)

[0038] In equation (3), λ is the torque Te λ Torque Te 02 The value ωc is determined according to factors such as the gear ratio of the transmission, the vehicle weight, and the drive torque. The frequency of the longitudinal vibration of the vehicle that occurs after the backlash is eliminated is determined by the gear ratio of the transmission, etc. Therefore, by setting ωc to a time constant that avoids that frequency, the longitudinal vibration of the vehicle can be suppressed. t is the elapsed time from timing t4. In equation (3), Te is the torque Te λ The time t at which this occurs is the end timing t5 of the fourth phase Ph4.

[0039] The parameters Teζ, ωa, b, and ωc in each formula can be determined based on the gear ratio, vehicle weight, engine torque, etc., as described above, but when determining them, the vehicle's front-rear vibration and the response delay to the accelerator operation should all be within the allowable range. The allowable range should be set by experiments, etc.

[0040] In the PAJ control, the ignition timing is controlled so that the engine torque changes according to the first torque profile. However, since the ignition timing has an advance limit and a retard limit, the region of the engine torque that can be realized by the ignition timing control (torque realization region) is limited. Therefore, in order to change the engine torque according to the first torque profile, it is necessary to control the intake amount so that the first torque profile falls within the torque realization region. However, since there is a delay between the operation of an intake device (not shown) that adjusts the intake amount and the change in the amount of intake air flowing into the internal combustion engine 1, it is not possible to handle a complex profile such as the first profile that is controlled by the ignition timing. Therefore, an engine torque profile (slow torque profile) for controlling the intake device is set, and the intake device is controlled according to this.

[0041] In the present embodiment, the intake device for adjusting the intake amount is assumed to be a throttle valve, but is not limited to this. For example, a variable valve mechanism capable of changing the opening / closing timing and the valve lift amount may be used.

[0042] Fig. 3 is a time chart for explaining a method for setting the slow torque profile. Fig. 3 shows a state in which the engine is switched from a driven state with the accelerator off to a driven state with the accelerator on. In the engine torque chart, solid line A shows the profile of the required torque up to the target engine torque according to the accelerator pedal depression amount (also called the required torque profile), solid line B shows the first torque profile, solid line C shows the slow torque profile, solid line D shows the slow upper limit torque profile, which will be described later, and solid line E shows the slow lower limit torque profile, which will be described later.

[0043] 4 is a flowchart showing a control routine for setting the slow torque profile. The control routine is stored in advance in the engine controller 9.

[0044] A specific description will be given below with reference to FIG. 3 and FIG.

[0045] When the accelerator opening increases at time T1 while driving with the accelerator off, the target engine torque is determined, and the required torque profile up to the target engine torque is also determined. The engine controller 9 then sets a first torque profile according to the required torque profile by the above-mentioned method, as shown by the solid line B in Fig. 3. The engine controller 9 also sets a slow torque profile for supplying the internal combustion engine 1 with just the right amount of intake air in order to realize the first torque profile.

[0046] Even if a slow torque profile is set and the intake device is controlled according to this, as described above, there is a delay between the operation of the intake device and the change in torque of the internal combustion engine 1. Taking this delay into account, the profile of the maximum engine torque that can be output by ignition timing control is set as the slow upper limit torque profile, and the minimum engine torque forward feel is set as the slow lower limit torque forward feel.

[0047] The slow upper limit torque profile is, for example, the profile of engine torque when the optimum ignition timing (MTB: Minimum Advance for Best Torque) is set, but since the intake amount is small due to the delay, it is lower than the slow torque profile. The slow lower limit torque profile is, for example, the profile of engine torque when the intake amount is small due to the delay and the timing is retarded to the misfire limit, and is even lower than the slow upper limit torque profile.

[0048] In other words, the above-mentioned torque realization region is a region sandwiched between the slow upper limit torque profile and the slow lower limit torque profile. The first torque profile must be within this region. For example, depending on the setting of the slow torque profile, there may be a time period in which the slow upper limit torque profile is lower than the first torque profile, and during this time, only a lower engine torque can be generated compared to the first torque profile. In this case, the driver may feel a sluggish acceleration, in other words, the acceleration responsiveness may be reduced.

[0049] Also, for example, if there is a time period when the slow lower limit torque profile is higher than the first torque profile, during this time, even if the ignition timing is retarded to the misfire limit, a higher engine torque than the first torque profile is generated. In this case, the shock of the vehicle caused by acceleration (G in FIG. 3) S ) may not be suppressed.

[0050] Therefore, when the accelerator operation amount changes, the engine controller 9 executes a control routine shown in FIG. 4 to set the slow torque profile.

[0051] In step S100, the engine controller 9 sets a first torque profile (solid line B).

[0052] In step S110, the engine controller 9 sets a provisional slow torque profile (solid line C). The final slow torque profile is determined by repeating a correction process described later, so the provisional slow torque profile may be set arbitrarily. However, in order to reduce the computational load required for the correction process, it is preferable that the provisional slow torque profile is close to the final slow torque profile. For example, a plurality of combination patterns of engine torque at the start of this control routine, target engine torque, gear ratio of the automatic transmission 3, etc. are prepared. Then, a slow torque profile that is considered to be suitable for each pattern is created by performing a simulation that takes into account the delay in the change in the intake amount. These are then stored in the engine controller 9, and the one that matches the conditions at time T1 is selected.

[0053] The provisional slow torque profile is, by its very nature, close to the first torque profile, but since it is realized by intake air amount control, which has a lower responsiveness than ignition timing control, it cannot be made into a complex profile like the first torque profile. Therefore, for example, the section until the target engine torque is reached may be divided into two stages, a first half section and a second half section, and the engine torque may increase at different gradients in the first half section and the second half section.

[0054] In the event that a collision between driveline gears occurs, such as during acceleration from an off-accelerator state, the period up until the collision is defined as the first half of the period, and the period after the collision is defined as the second half of the period, with the gradient of the first half of the period being made smaller than that of the second half of the period. This is because the rate of increase in engine torque is suppressed in the first half of the period to suppress shock caused by a collision between driveline gears, and the rate of increase in engine torque is increased in the second half of the period to improve acceleration responsiveness. In this case, the smaller the engine torque at the start of this control routine (the larger the absolute value of the negative torque), the smaller the gradient of the first half of the period is made. This is because the smaller the engine torque is, the greater the shock when the engine torque turns positive.

[0055] On the other hand, when there is no collision between the drivetrain gears, such as when accelerating from a cruising state with the accelerator on, there is no need to consider suppressing shock, so the gradient at which the engine torque increases can be made different from that in the case where a collision occurs. For example, the gradient in the first half section can be made larger than the gradient in the second half section.

[0056] In addition, the larger the target engine torque, the larger the gradient of the first and second half sections is set. This is because a large target engine torque means that the driver is more concerned with acceleration response (G in FIG. 3) than with suppressing shocks. L ) can be considered to have priority.

[0057] In addition, the larger the gear ratio of the automatic transmission 3, the larger the gradient of the first and second half sections is made. This is because the larger the gear ratio, the larger the driving force for the same engine torque becomes, making it easier for shock to occur, so by making the gradient of the increase in engine torque smaller, shock can be suppressed.

[0058] When setting the gradients of the first and second half sections, it may be possible to take into consideration whether the torque converter 2 is locked up. When the torque converter 2 is locked up, the change in driving force when the engine torque changes is greater than when the torque converter 2 is not locked up. Therefore, in order to suppress shocks caused by changes in engine torque, the gradient of the increase in engine torque is made smaller when the torque converter 2 is locked up than when the torque converter 2 is not locked up.

[0059] Returning to the explanation of the flowchart.

[0060] In step S120, the engine controller 9 sets a slow upper limit torque profile (solid line D). The slow upper limit torque profile is a profile of the upper limit value of the engine torque that can be realized by ignition timing control at an intake air amount that takes into account a response delay to a change in the intake air amount when the intake air amount is controlled according to the provisional slow torque profile.

[0061] In step S130, the engine controller 9 sets a slow lower limit torque profile (solid line E). The slow lower limit torque profile is a profile of the lower limit value of the engine torque that can be realized by ignition timing control at an intake air amount that takes into account a response delay to a change in the intake air amount when the intake air amount is controlled according to the provisional slow torque profile.

[0062] In step S140, the engine controller 9 compares the slow upper limit torque profile with the first torque profile. Then, it is determined whether or not the engine torque on the slow upper limit torque profile (slow upper limit torque) is equal to or greater than the engine torque on the first torque profile (first torque) at the same time in the entire section until the target engine torque is reached. If the slow upper limit torque is equal to or greater than the first torque in the entire section, the process of step S150 is executed, and if not, the process returns to step S110.

[0063] It is desirable that the slow upper limit torque is not only equal to or greater than the first torque in all sections, but also that the slow upper limit torque and the first torque are as close as possible. This is because the closer the slow upper limit torque is to the first torque, the more it is possible to set an ignition timing closer to the optimal ignition timing, and the decrease in thermal efficiency due to ignition timing retardation can be suppressed. Therefore, in addition to the slow upper limit torque being equal to or greater than the first torque in all sections, if the slow upper limit torque profile and the first torque profile overlap in about 80% of the entire section, the process may proceed to step S150. In this case, even if the slow upper limit torque is equal to or greater than the first torque in all sections, if the overlapping section is less than 80%, the process returns to step S110.

[0064] In step S110, which is performed again, engine controller 9 corrects the slow upper limit torque profile so as to approach the first torque profile based on the result of the comparison in step S140, and sets the corrected slow upper limit torque profile as a provisional slow torque profile.

[0065] In step S150, the engine controller 9 compares the slow lower limit torque profile with the first torque profile. Then, it is determined whether the engine torque (slow lower limit torque) on the slow lower limit torque profile at the same time is equal to or less than the first torque in the entire section until the target engine torque is reached. If the slow lower limit torque is equal to or less than the first torque in the entire section, the process of step S160 is executed, and if not, the process returns to step S110.

[0066] It is desirable that not only the slow lower limit torque is equal to or less than the first torque in all sections, but also that the slow lower limit torque and the first torque are as far apart as possible. The greater the difference between the first torque and the slow lower limit torque, the more likely it is that the ignition timing can be set farther away from the misfire limit. However, if the slow upper limit torque profile approaches the first torque profile by repeating the processes of steps S110 to S140, the slow lower limit torque profile will naturally deviate from the first torque profile.

[0067] In step S160, the engine controller 9 sets the tentative slow torque profile as the slow torque profile.

[0068] By controlling the intake device in accordance with the slow torque profile set by the above control routine, it is possible to ensure an intake amount that enables the first torque profile to be realized by ignition timing control.

[0069] The method of setting the provisional slow torque profile is not limited to the above. For example, the provisional slow torque profile may be a profile that changes with a predetermined gradient from the engine torque at the time when the accelerator operation amount changes to the target engine torque according to the accelerator operation amount. This is because the provisional slow torque profile will eventually converge to the same slow torque profile as in this embodiment by repeating the control routine of FIG. 4.

[0070] Furthermore, the processes of steps S130 and S150 are not essential because, as long as the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range, the driver will at least not feel a sluggish acceleration.

[0071] As described above, in this embodiment, when the running state of a vehicle using the internal combustion engine 1 as a drive source changes according to the accelerator operation amount, an engine torque control method is provided in which the engine controller (controller) 9 sets a first torque profile, which is a torque profile up to a target engine torque according to the accelerator operation amount, and controls the engine torque according to the first torque profile. In this method, the engine controller 9 executes step S100 (first step) of setting a first torque profile, which is a torque profile that suppresses shocks that occur with changes in the running state, step S110 (second step) of setting a provisional slow torque profile, which is a provisional value of a slow torque profile, which is a profile of an engine torque used to control an intake device that adjusts the intake amount of the internal combustion engine 1, based on the accelerator operation amount, step S120 (third step) of calculating a slow upper limit torque profile, which is a profile of an upper limit value of the engine torque that can be realized by ignition timing control when the intake amount is controlled according to the provisional slow torque profile, and step S140 (fourth step) of comparing the slow upper limit torque profile with the first torque profile. If the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range, step S160 (fifth step) is executed to set the provisional slow torque profile as the slow torque profile, and if there is an area where the slow upper limit torque profile is smaller than the first torque profile, the process returns to step S110 to set a new provisional slow torque profile by correcting the provisional slow torque profile, and then steps S120 and S140 are executed, and the process is repeated until the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range. This makes it possible to secure an intake amount that can realize the first torque profile.

[0072] In this embodiment, the engine controller 9 executes step S130 (step 3-2) of calculating a slow lower limit torque profile, which is a profile of the lower limit value of the engine torque that can be realized by ignition timing control when the intake amount is controlled according to the provisional slow torque profile, between step S120 and step S140, and step S150 (step 4-2) of comparing the slow lower limit torque profile with the first torque profile between step S140 and step S160. If the slow lower limit torque profile is lower than the first torque profile over the entire range, step S160 is executed, and if there is a region where the slow lower limit torque profile is larger than the first torque profile, the process returns to step S110 to set a new provisional slow torque profile by correcting the provisional slow torque profile, and then repeats the process of steps S120 to S150 until the slow lower limit torque profile is lower than the first torque profile over the entire range. This makes it possible to control the engine torque according to the first torque profile, and it is possible to achieve both suppression of vehicle shock and acceleration responsiveness.

[0073] In this embodiment, when the vehicle accelerates due to an increase in the accelerator operation amount, the engine controller 9 divides the section until the target engine torque is reached into a first half section and a second half section, and sets a provisional slow torque profile in which the engine torque increases at different slopes in the first half section and the second half section. For example, when switching from an accelerator-off state to an accelerator-on state, the tendency of the slope of the engine torque changes between before and after the collision of the drive system gears. Therefore, if the period until the collision is set as the first half section and the period after the collision is set as the second half section, a provisional slow torque profile that matches this tendency can be set.

[0074] In this embodiment, in the case of acceleration switching from a driven state to a driving state, the engine controller 9 makes the second torque gradient, which is the gradient of the engine torque change in the latter half section, larger than the first torque gradient, which is the gradient of the engine torque change in the first half section. This makes it possible to suppress the impact of collision between the drive gears and to suppress a sluggish feeling during acceleration.

[0075] In this embodiment, the engine controller 9 sets the second torque gradient to a different magnitude for acceleration when switching from a driven state to a driving state and acceleration from a driving state. When accelerating from a driving state, no collision occurs between the drive system gears, so a profile for suppressing collision between the drive system gears is not necessary. Therefore, by making the magnitude of the second torque gradient different between the two, a slow torque profile can be set according to each situation.

[0076] In this embodiment, the engine controller 9 sets the second torque gradient to a different magnitude depending on whether the torque converter 2 is locked up or not. The way in which the driving force changes when the engine torque changes differs depending on whether the torque converter 2 is locked up or not, but this embodiment makes it possible to set the second torque gradient to suppress shock caused by the change in driving force (i.e., shock caused by collision between drive system gears) according to each situation.

[0077] In this embodiment, the engine controller 9 sets the second torque gradient based on the engine torque at the start of step S100, the target engine torque, or the target gear ratio of the automatic transmission (transmission) 3. The allowable range of shock caused by changes in engine torque varies according to the target engine torque. In addition, the magnitude and manner of change of the driving force differ according to the engine torque and gear ratio when the accelerator operation amount changes. Therefore, according to this embodiment, a slow torque profile can be set that achieves both suppression of shock caused by collision between drive system gears and acceleration responsiveness according to the driving situation.

[0078] In this embodiment, the engine controller 9 sets a larger second torque gradient as the target engine torque increases. As the target engine torque increases, the driver places a higher priority on acceleration response and is therefore able to tolerate larger shocks. Therefore, according to this embodiment, a slow torque profile with better acceleration response can be set.

[0079] In this embodiment, the engine controller 9 sets a smaller second torque gradient as the target gear ratio increases. As the gear ratio increases, the driving force at the same engine torque increases and shocks tend to occur. Therefore, according to this embodiment, shocks caused by changes in engine torque can be suppressed.

[0080] In this embodiment, in the case of acceleration switching from a driven state to a driving state, the engine controller 9 sets a smaller first torque gradient as the engine torque at the start of step S100 becomes smaller. Since the shock when the engine torque turns positive becomes larger as the engine torque at the start of step S100 becomes smaller (the absolute value of the negative torque becomes larger), this embodiment can suppress the shock caused by the change in engine torque.

[0081] [Second embodiment] Next, a second embodiment of the present invention will be described. While the first embodiment is a situation in which the accelerator is switched from an off state to an on state and the vehicle accelerates, this embodiment is a situation in which the accelerator is switched from an on state to an off state and the vehicle decelerates. The engine torque control routine is basically the same as that of the first embodiment, but the method of setting the provisional slow torque profile in step S110 is different. The following description will focus on this difference.

[0082] Fig. 5 is a time chart for explaining the method of setting the slow torque profile in this embodiment. As in Fig. 3, the solid line A in the engine torque chart indicates the profile of the required torque up to the target engine torque according to the accelerator pedal depression amount (also called the required torque profile), the solid line B indicates the first torque profile, the solid line C indicates the slow torque profile, the solid line D indicates the slow upper limit torque profile, and the solid line E indicates the slow lower limit torque profile.

[0083] When the accelerator is released and the target engine torque changes, the controller 10 accordingly sets a first torque profile that achieves both suppression of shock due to collision between driveline gears and good deceleration responsiveness, as in the case of acceleration (step S100).

[0084] Next, the controller 10 sets a tentative slow torque profile to be used for controlling the intake device (step S110). The tentative slow torque profile is a profile obtained by subjecting the required torque profile to a first-order lag filter process with a predetermined time constant throughout the entire process until the target engine torque is reached, or a profile close to this.

[0085] The time constant is set in advance by performing a simulation that takes into account the delay in the amount of intake air, as in the first embodiment. The larger the gear ratio, the larger the time constant. This is because, even if the engine torque is the same, the driving force increases as the gear ratio increases, so by making the time constant larger (i.e., by making the change in engine torque more gradual), shocks can be suppressed.

[0086] The magnitude of the time constant may be changed depending on whether the torque converter 2 is locked up or not. When the torque converter 2 is locked up, the change in driving force when the engine torque changes is greater than when the torque converter 2 is not locked up. Therefore, in order to suppress shock caused by changes in engine torque, the time constant is made larger when the torque converter 2 is locked up than when the torque converter 2 is not locked up.

[0087] Once the provisional slow torque profile has been set as described above, the processes of steps S120 to S160 are executed in the same manner as in the first embodiment to set the slow torque profile.

[0088] As a result, even when decelerating by switching from an accelerator-on state to an accelerator-off state, it is possible to ensure an intake amount that enables the first torque profile to be realized by ignition timing control, as in the first embodiment.

[0089] In this embodiment, the so-called foot release, which switches from the accelerator on state to the accelerator off state, has been described, but the same can be applied to the so-called foot return, which maintains the accelerator on state with a smaller accelerator operation amount. However, in the case of foot return, since no collision occurs between the drive system gears, the engine torque can be reduced more quickly than in the case of foot release. Therefore, in the case of foot return, the time constant can be made smaller than in the case of foot release.

[0090] As described above, in this embodiment, when the accelerator operation amount is decreased and the vehicle is decelerated, the engine controller 9 sets a profile obtained by subjecting the change in the target engine torque to first-order lag filtering with a predetermined time constant as the provisional slow torque profile. It is known that the first torque profile during deceleration tends to be close to a curve obtained by subjecting the change in the target engine torque to first-order lag filtering. Therefore, according to this embodiment, it is possible to set a provisional slow torque profile close to the first torque profile to be realized.

[0091] In this embodiment, the engine controller 9 sets different time constants for switching from a driving state to a driven state and for decelerating while maintaining the driving state. When switching from a driving state to a driven state (i.e., when the foot is released), collision between the drive gears occurs, and it is necessary to suppress the shock caused by this, whereas when decelerating while maintaining the driving state (i.e., when the foot is returned), such collision does not occur. Therefore, according to this embodiment, it is possible to set a time constant according to the situation.

[0092] In this embodiment, the engine controller 9 sets different time constants depending on whether the torque converter 2 is locked up or not. The way in which the driving force changes when the engine torque changes differs depending on whether the torque converter 2 is locked up or not, but this embodiment makes it possible to set a time constant for suppressing shocks caused by changes in the driving force (i.e., shocks caused by collisions between drive system gears) according to each situation.

[0093] In this embodiment, the engine controller 9 sets the time constant based on the engine torque at the start of step S100, the target engine torque, or the target gear ratio of the automatic transmission 3. The allowable range of shock caused by changes in engine torque varies according to the target engine torque. In addition, the magnitude and manner of change of the driving force differ according to the engine torque and gear ratio when the accelerator operation amount changes. Therefore, according to this embodiment, a time constant can be set that achieves both suppression of shock caused by collision between drive system gears and acceleration responsiveness according to the driving conditions.

[0094] In this embodiment, the engine controller 9 sets a smaller time constant as the target gear ratio increases. Even if the engine torque is the same, the driving force increases as the gear ratio increases, so that, for example, by setting a larger time constant as the gear ratio increases, shocks caused by changes in driving force can be suppressed.

[0095] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0096] 1 internal combustion engine, 2 torque converter, 3 automatic transmission, 5 final drive, 8 AT controller, 9 engine controller, 10 controller

Claims

1. 1. An engine torque control method, comprising: a controller setting a first torque profile which is a torque profile up to a target engine torque according to an accelerator operation amount when a running state of a vehicle driven by an internal combustion engine changes according to the accelerator operation amount, and controlling the engine torque according to the first torque profile, The controller: A first step of setting the first torque profile, which is a torque profile that suppresses shocks that occur due to changes in running conditions; a second step of setting a provisional slow torque profile, which is a provisional value of a slow torque profile, which is a profile of the engine torque used for controlling an intake device that adjusts an intake amount of the internal combustion engine, based on the accelerator operation amount; a third step of calculating a slow upper limit torque profile, which is a profile of an upper limit value of the engine torque that can be realized by ignition timing control when the intake amount is controlled according to the provisional slow torque profile; a fourth step of comparing the slow upper limit torque profile with the first torque profile; When the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range, a fifth step is executed in which the provisional slow torque profile is set as the slow torque profile; An engine torque control method characterized in that, when there is a region where the slow upper limit torque profile is smaller than the first torque profile, the process returns to the second step to set a new provisional slow torque profile by correcting the provisional slow torque profile, and then the process of executing the third step and the fourth step is repeated until the slow upper limit torque profile becomes equal to or greater than the first torque profile over the entire region.

2. 2. The engine torque control method according to claim 1, The controller: a 3-2 step of calculating a slow lower limit torque profile, which is a profile of a lower limit value of the engine torque that can be realized by ignition timing control when the intake amount is controlled according to the provisional slow torque profile between the 3rd step and the 4th step; between the fourth step and the fifth step, a fourth-2 step of comparing the slow lower limit torque profile with the first torque profile; When the slow lower limit torque profile is lower than the first torque profile over the entire range, the fifth step is executed; When there is a region where the slow lower limit torque profile is larger than the first torque profile, the engine torque control method returns to the second step, corrects the provisional slow torque profile to set a new provisional slow torque profile, and then repeats the process of executing the third step, the third-2 step, the fourth step, and the fourth-2 step until the slow lower limit torque profile falls below the first torque profile over the entire region.

3. 2. The engine torque control method according to claim 1, The controller: When the vehicle accelerates due to an increase in the accelerator operation amount, The engine torque control method includes setting the provisional slow torque profile such that a period until the target engine torque is reached is divided into a first half period and a second half period, and the engine torque increases at different slopes in the first half period and the second half period.

4. 4. The engine torque control method according to claim 3, The controller: In the case of acceleration switching from a driven state to a driving state, The engine torque control method includes making a second torque gradient, which is a gradient of the engine torque change in the latter half section, larger than a first torque gradient, which is a gradient of the engine torque change in the former half section.

5. 4. The engine torque control method according to claim 3, The controller: The engine torque control method includes setting a second torque gradient, which is the gradient of the engine torque change in the latter half section, to different magnitudes in the case of acceleration when switching from a driven state to a driving state and in the case of acceleration from a driving state.

6. 4. The engine torque control method according to claim 3, The controller: The engine torque control method includes setting a second torque gradient, which is a gradient of the engine torque change in the latter half section, to different magnitudes depending on whether the torque converter is locked up or not.

7. 4. The engine torque control method according to claim 3, The engine torque control method, wherein the controller sets a second torque slope, which is the slope of the engine torque change in the latter half section, based on the engine torque at the start of the first step, the target engine torque, or a target gear ratio of a transmission.

8. 8. The engine torque control method according to claim 7, The engine torque control method, wherein the controller sets the second torque gradient to be larger as the target engine torque is larger.

9. 8. The engine torque control method according to claim 7, The engine torque control method, wherein the controller sets the second torque gradient smaller as the target gear ratio increases.

10. 8. The engine torque control method according to claim 7, The engine torque control method further comprises: in the case of acceleration switching from a driven state to a driving state, the controller sets a smaller value as the first torque slope, which is the slope of the engine torque change in the first half section, the smaller the engine torque at the start of the first step.

11. 2. The engine torque control method according to claim 1, The controller: An engine torque control method in which, when the accelerator operation amount is decreased and the vehicle decelerates, a profile obtained by subjecting the change in the target engine torque to first-order lag filtering with a predetermined time constant is set as the provisional slow torque profile.

12. 12. The engine torque control method according to claim 11, The controller: The engine torque control method includes setting the time constant to a different value when switching from a driving state to a driven state and when decelerating while maintaining the driving state.

13. 12. The engine torque control method according to claim 11, The engine torque control method, wherein the controller sets the time constant to a different value depending on whether the torque converter is locked up or not.

14. 12. The engine torque control method according to claim 11, The engine torque control method, wherein the controller sets the time constant based on the engine torque at the start of the first step, the target engine torque, or a target gear ratio of a transmission.

15. 15. The engine torque control method according to claim 14, The engine torque control method, wherein the controller sets the time constant to be smaller as the target gear ratio is larger.

16. 1. An engine torque control device which, when a running state of a vehicle driven by an internal combustion engine changes in response to an accelerator operation amount, sets a first torque profile which is a torque profile up to a target engine torque in response to the accelerator operation amount, and controls engine torque in accordance with the first torque profile, a first torque profile setting unit that sets the first torque profile, which is a torque profile that suppresses shocks that occur due to changes in running conditions; a provisional slow torque profile setting unit that sets a provisional slow torque profile, which is a provisional value of a slow torque profile that is a profile of the engine torque used for controlling an intake device that adjusts an intake amount of the internal combustion engine, based on the accelerator operation amount; a slow upper limit torque profile calculation unit that calculates a slow upper limit torque profile, which is a profile of an upper limit value of the engine torque that can be realized by ignition timing control when an intake amount is controlled according to the provisional slow torque profile; a comparison unit that compares the slow upper limit torque profile with the first torque profile; a slow torque profile setting unit that sets the provisional slow torque profile as a slow torque profile when the slow upper limit torque profile is equal to or greater than the first torque profile over the entire range; Equipped with an upper limit torque profile calculation unit calculating a new slow upper limit torque profile based on the new provisional slow torque profile; and a comparison unit comparing the new provisional slow torque profile with the new slow upper limit torque profile, the slow upper limit torque profile being calculated based on the new provisional slow torque profile, and the comparison unit repeating this process until the slow upper limit torque profile becomes equal to or greater than the first torque profile over the entire range.

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