Engine torque control method and engine torque control device

Abstract

To suppress a shock that a vehicle has if a travel state of the vehicle changes in a non-lock-up state.SOLUTION: An engine torque control method that controls the engine torque of a vehicle comprising an internal combustion engine 1, an automatic transmission 3, and a torque converter 2 with a lock-up function is characterized in that when a travel state of the vehicle changes from a driven state to a driving state with the torque converter 2 in a non-lock-up state, a controller 9 lowers the engine torque down to predetermined torque once difference rotation as a difference between an input rotating speed and an output rotating speed of the torque converter 2 enters a cross region as a range in which a shock generated by a collision between driving system gears accompanying the change in the travel state is large enough to have sensitivity to an engine torque change speed, and then limits the engine torque change speed thereafter until the difference rotation exits from the cross region, thereby suppressing the shock.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, thereby suppressing shocks that occur to the vehicle with changes in the driving state, for example shocks due to collisions between drive system gears. [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, the control described in the above document is based on the premise that the torque converter is in a lock-up state, i.e., that the input rotation speed and output rotation speed of the torque converter are the same. Therefore, even if the control described in the above document is performed when the torque converter is not in a lock-up state, i.e., when the input rotation speed and output rotation speed of the torque converter are different, there is a risk that the shock cannot be suppressed.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to suppress shocks that occur in the vehicle due to changes in the running conditions when the torque converter is not locked up and the running conditions of the vehicle change. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an engine torque control method for controlling engine torque of a vehicle including an internal combustion engine, an automatic transmission, and a torque converter with a lock-up function disposed between the internal combustion engine and the automatic transmission. In this method, when the torque converter is in a non-lock-up state and the vehicle's running state is switched from a driven state to a driving state, a controller reduces the engine torque to a predetermined torque when a differential rotation speed, which is a difference between an input rotation speed and an output rotation speed of the torque converter, enters a cross region, which is a range in which the magnitude of a shock caused by a collision between drive system gears accompanying the switching of the running state is sensitive to the engine torque change speed, and suppresses the shock by limiting the engine torque change speed from there until the differential rotation speed leaves the cross region. Effect of the Invention

[0007] According to the above aspect, when the vehicle running condition changes while the torque converter is not in a lockup state, shocks occurring in the vehicle due to the change in the running condition can be suppressed. [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 when the engine torque control according to the embodiment of the present invention is executed. [Figure 4] FIG. 4 is a flowchart showing a control routine for engine torque control according to the embodiment of the present invention. 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 PAJ control is executed when switching from a driven state to a driving state. In order to explain basic PAJ control, it is assumed that the torque converter 2 is in a lock-up state. Hereinafter, this PAJ control is also referred to as normal PAJ control to distinguish it from the control in the cross region described later. The engine torque in the driven state is defined as coast torque Te0 (negative value), and the target engine torque according to the accelerator pedal operation amount is defined as 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 λ The 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. ζ The 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 torque profile is set as above in order to control the rotation speed when the first phase Ph1 enters the second phase Ph2. In formula (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 02 Immediately 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 02Torque 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 response delay to accelerator operation (also called acceleration response) should all be within an allowable range. The allowable range should be set by experiment, etc.

[0040] In the lockup state, the above-mentioned PAJ control can suppress shocks caused by collisions between drive system gears when switching from a driven state to a driving state (hereinafter simply referred to as "shocks"). However, in the non-lockup state, there is a difference between the input rotation speed and the output rotation speed of the torque converter 2, so the above-mentioned PAJ control may not be able to suppress shocks.

[0041] Therefore, in the non-lockup state, shock is suppressed by the control described below. In the following description, the difference between the input rotation speed and the output rotation speed is called the differential rotation. When the input rotation speed is lower, the differential rotation is negative, and when the input rotation speed is higher, the differential rotation is positive.

[0042] In a non-lockup state, the drivetrain gears collide with each other near the timing when the difference rotation is reversed. Therefore, the shock can be suppressed by suppressing the rate of increase in the input rotation speed (i.e., the rate of increase in the engine torque) near that timing. However, the slower the rate of increase in the engine torque, the lower the vehicle's acceleration responsiveness, so it is necessary to suppress it within a range that ensures an acceleration responsiveness that does not dissatisfy the driver.

[0043] In addition, since the longer the period for suppressing the rate of increase of the engine torque, the more the acceleration response of the vehicle decreases, it is undesirable to make the suppression period longer than necessary. Therefore, in this embodiment, the period for suppressing the rate of increase of the input rotation speed is set as follows.

[0044] According to the inventors' research, the magnitude of the shock is sensitive to the rate of increase of the engine torque (i.e., the rate of change of the engine torque) only in a predetermined region (hereinafter also referred to as the cross region) where the magnitude of the absolute value of the differential rotation is relatively small. In other words, when the differential rotation is negative, the magnitude of the generated shock does not change even if the rate of change of the engine torque is changed until the cross region is entered. When the differential rotation is positive, the magnitude of the generated shock does not change even if the rate of change of the engine torque is changed after the cross region is left. Therefore, the rate of change of the engine torque is suppressed in the cross region.

[0045] Here, a method for setting the start differential rotation and end differential rotation of the cross area will be described.

[0046] [Setting the starting differential rotation] A certain negative differential speed is set, and the engine speed is increased at a number of different engine torque change speeds until the differential speed is reached, and the magnitude of shock at each engine torque change speed is compared. If the magnitude of the shock does not change depending on the engine torque change speed, that is, if sensitivity to the engine torque change speed is not recognized, the absolute value of the differential speed is reduced and a similar comparison is made. This is repeated until sensitivity is recognized, and the differential speed at which sensitivity is recognized is set as the start of the cross region (start differential speed).

[0047] For example, a negative differential speed is set to -200 rpm, five different engine torque change speeds are set, the engine speed is increased until the differential speed reaches -200 rpm, and the magnitude of shock at each engine torque change speed is compared. If the comparison shows no difference in the magnitude of the shock, the absolute value of the negative speed is reduced (for example, -150 rpm) and a similar comparison is made. This is repeated, and if a difference in the magnitude of the shock occurs at, for example, -50 rpm, -50 rpm is set as the starting differential speed of the cross region.

[0048] [Setting End Rotation Difference] A certain positive differential speed is set, and the engine speed is increased from the differential speed at a number of different engine torque change speeds, and the magnitude of shock at each engine torque change speed is compared. If the magnitude of the shock does not change depending on the engine torque change speed, that is, if sensitivity to the engine torque change speed is not recognized, the absolute value of the differential speed is reduced and a similar comparison is made. This is repeated until sensitivity is recognized, and the differential speed at which sensitivity is recognized is set as the end (end differential speed) of the cross region. For example, a certain positive differential speed is set to 200 rpm, five different engine torque change speeds are set, and the engine speed is increased from a state where the differential speed is 200 rpm, and the magnitude of shock at each engine torque change speed is compared. If the comparison shows that there is no difference in the magnitude of the shock, the absolute value of the negative speed is reduced (for example, 150 rpm) and a similar comparison is made. This is repeated, and if a difference in the magnitude of the shock occurs at, for example, 25 rpm, 25 rpm is set as the start differential speed of the cross region.

[0049] The above-mentioned start differential rotation and end differential rotation are obtained in advance by simulation or the like, and are stored in the engine controller 9.

[0050] In addition, since the start differential rotation and the end differential rotation may vary depending on the vehicle speed and the gear ratio of the automatic transmission 3, it is desirable to determine the start differential rotation and the end differential rotation for each vehicle speed and gear ratio when the accelerator is operated and map them.

[0051] The start differential rotation and end differential rotation (i.e., the cross region) can also be estimated based on the specifications of the internal combustion engine 1, the torque converter 2, the automatic transmission 3, etc., but by clarifying the range that affects the shock as described above, it is possible to avoid not being able to completely suppress the shock or avoiding an unnecessary deterioration in acceleration responsiveness.

[0052] 3 is a time chart in which the engine controller 9 executes the control according to this embodiment when switching from a driven state to a driving state in a non-lockup state. In the engine torque chart, solid line A indicates the profile up to the target torque according to the accelerator operation amount, dashed line B indicates the profile by normal PAJ control, dashed line C indicates the profile of the output upper limit torque that takes into account the delay in the change in the intake amount compared to the profile by normal PAJ control, and solid line D indicates the profile by the control according to this embodiment. In the rotation speed chart, solid line E indicates the input rotation speed of the torque converter 2 (hereinafter also simply referred to as "input rotation speed"), and solid line F indicates the output rotation speed of the torque converter 2 (hereinafter also simply referred to as "output rotation speed").

[0053] In addition, in FIG. 3, the differential rotation is in the cross region from time t2 to t3 (PhB).

[0054] When the target torque changes due to a change in the accelerator operation amount at time t1, a torque profile (dashed line B) is set in the same way as with normal PAJ control, and based on this, a profile of the maximum output torque (dashed line C) is set that takes into account the delay in the change in the intake air volume. Then, the engine torque is increased according to the profile of the maximum output torque. This increases the engine speed, that is, the input speed of the torque converter 2. At this stage, the output shaft of the torque converter 2 is rotated by the drive wheels 7, and the output speed is higher than the input speed.

[0055] When the differential rotation speed enters the cross region at time t2, the engine torque is stepped down to a predetermined torque (also called a destination torque). The destination torque is set to a magnitude that allows the engine speed at time t2 to be maintained. Note that, like the start differential rotation speed and the end differential rotation speed, the destination torque may also vary depending on the vehicle speed and the gear ratio of the automatic transmission 3, so it is desirable to set the destination torque depending on the vehicle speed and the gear ratio when the accelerator is operated.

[0056] Then, until time t3, the engine torque is increased while limiting the engine torque change rate. The term "limit" here means limiting the engine torque change rate to the maximum rate that can be achieved by ignition timing control. Specifically, the limit is set to a value that can achieve both shock suppression and acceleration responsiveness.

[0057] The magnitude of shock and acceleration responsiveness that a driver can tolerate varies depending on the vehicle model, and are set according to suitability, etc. For example, minivans and the like tend to prioritize shock suppression over acceleration responsiveness, while sports types and the like tend to prioritize acceleration responsiveness over shock suppression.

[0058] In addition, the magnitude of shock and acceleration responsiveness that the driver can tolerate also differs depending on driving conditions such as the vehicle speed, the gear ratio of the automatic transmission 3, and the accelerator operation amount. For example, the higher the gear ratio, the faster the engine speed increases, and the greater the shock tends to be. Therefore, the higher the gear ratio, the smaller the engine torque change rate may be. Also, for example, the higher the vehicle speed, the shorter the time it takes to exit the cross region. Therefore, the higher the vehicle speed, the smaller the engine torque change rate may be. Also, for example, when the accelerator pedal is depressed to a large extent, it can be assumed that the driver prioritizes acceleration responsiveness over suppression of shock. Therefore, the engine torque change rate in the cross region may be increased as the accelerator opening or the accelerator opening change rate is increased. Therefore, the engine torque change rate may be mapped using the vehicle speed, gear ratio, and accelerator opening or the accelerator opening change rate as parameters, and the engine torque change rate may be set based on the map.

[0059] When the end differential rotation of the cross region is reached at time t3, engine torque control is performed in the same manner as normal PAJ control.

[0060] That is, the engine torque increases according to the output upper limit torque profile from time t1 to t2 (PhA), and then decreases to the destination torque from time t2 to t3 (PhB) before increasing at a predetermined engine torque change rate. Then, from time t3 onwards, the engine torque at time t3 is maintained from time t3 to t4 (PhC) as in normal PAJ control, and the engine torque increases from time t4 onwards.

[0061] 4 is a flowchart showing a control routine for the above-mentioned engine torque control executed by the engine controller 9. This control routine is preprogrammed in the engine controller 9.

[0062] In step S100, the gear ratio of the automatic transmission 3 and the output rotation speed of the torque converter 2 are obtained. The gear ratio is obtained through communication with the AT controller 8, and the output rotation speed is obtained from a sensor (not shown).

[0063] In step S110, the start and end differential rotation speeds of the cross region, the destination torque, and the engine torque change rate in the cross region are set.

[0064] In step S120, the engine torque is increased according to the output upper limit torque profile.

[0065] In step S130, it is determined whether or not the differential rotation has entered the cross region. If it has, the process of step S140 is executed, and if it has not entered, the process returns to step S120.

[0066] In step S140, the engine torque is controlled to the target torque set in step S110.

[0067] In step S150, the engine torque is increased at an accelerating rate to the engine torque set in step S110.

[0068] In step S160, it is determined whether the differential rotation has left the cross region, and if so, the process proceeds to step S170, and if not, the process returns to step S150.

[0069] In step S170, the control is switched to normal PAJ control, and this routine ends.

[0070] As described above, in this embodiment, an engine torque control method is provided for controlling the engine torque of a vehicle including an internal combustion engine 1, an automatic transmission 3, and a torque converter 2 with a lock-up function disposed between the internal combustion engine 1 and the automatic transmission 3. In this method, when the torque converter is in a non-lock-up state and the vehicle's running state is switched from a driven state to a driving state, the engine controller (controller) 9 reduces the engine torque to a drop destination torque (predetermined torque) when the differential rotation, which is the difference between the input rotation speed and the output rotation speed of the torque converter 2, enters a cross region in which the magnitude of the shock caused by the collision between the drive system gears accompanying the switching of the running state is sensitive to the engine torque change speed, and suppresses the shock by limiting the engine torque change speed from there until the differential rotation leaves the cross region. This makes it possible to suppress the shock caused by the collision between the drive system gears accompanying the switching of the running state. In addition, since the engine torque change speed can be increased compared to the cross region before and after entering the cross region, it is possible to achieve both shock suppression and acceleration responsiveness.

[0071] In this embodiment, the engine controller 9 sets the minimum differential rotation where the input rotation speed is lower than the output rotation speed and where the magnitude of the shock is sensitive to the engine torque change speed as the start differential rotation of the cross region, and determines that the cross region has been entered when the differential rotation becomes the start differential rotation. This makes it clear when the cross region is entered, so that it is possible to start limiting the engine torque change speed at an appropriate timing. In other words, it is possible to increase the engine torque as much as possible until the cross region is entered, so that it is possible to suppress a decrease in acceleration responsiveness while suppressing shock.

[0072] In this embodiment, the engine controller 9 sets the minimum differential rotation at which the input rotation speed is higher than the output rotation speed and the magnitude of the shock is no longer sensitive to the engine torque change speed as the end differential rotation of the cross region, and determines that the cross region has been exited when the differential rotation reaches the end differential rotation. This makes it clear when the cross region is exited, so that the restriction on the engine torque change speed can be released at an appropriate timing. In other words, it is possible to suppress the acceleration responsiveness from being unnecessarily deteriorated in order to suppress the shock.

[0073] In this embodiment, the engine controller 9 increases the engine torque change rate in the cross region as the accelerator opening or the accelerator opening change rate increases. This makes it possible to achieve acceleration responsiveness according to the driver's intention in a situation where the driver is deemed to prioritize acceleration responsiveness over shock suppression.

[0074] In this embodiment, the torque to be dropped is set to a value that can at least maintain the input rotation speed when the vehicle enters the cross region, thereby preventing the driver from feeling that the acceleration has dropped when the vehicle enters the cross region.

[0075] In this embodiment, the engine controller 9 reduces the engine torque change rate in the cross region as the gear ratio of the automatic transmission 3 increases or the vehicle speed increases. This makes it possible to appropriately suppress shocks according to the driving conditions.

[0076] 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]

[0077] 1 internal combustion engine, 2 torque converter, 3 automatic transmission, 5 final drive, 8 AT controller, 9 engine controller, 10 controller

Claims

1. An engine torque control method for controlling engine torque of a vehicle including an internal combustion engine, an automatic transmission, and a torque converter with a lock-up function disposed between the internal combustion engine and the automatic transmission, comprising: When the torque converter is in a non-lockup state and the running state of the vehicle is switched from a driven state to a driving state, the controller When the differential rotation, which is the difference between the input rotation speed and the output rotation speed of the torque converter, enters a cross region in which the magnitude of the shock caused by a collision between drive system gears accompanying the change in driving state is sensitive to the engine torque change rate, the engine torque is reduced to a predetermined torque, and the engine torque change rate is limited from there until the differential rotation leaves the cross region, thereby suppressing the shock.

2. 2. The engine torque control method according to claim 1, The controller: A minimum differential rotation at which the input rotation speed is lower than the output rotation speed and at which the magnitude of the shock is sensitive to the engine torque change rate is set as a start differential rotation of the cross region; The engine torque control method determines that the engine has entered the cross region when the differential rotation speed reaches the start differential rotation speed.

3. 2. The engine torque control method according to claim 1, The controller: a minimum differential rotation at which the input rotation speed is higher than the output rotation speed and the magnitude of the shock is insensitive to the engine torque change rate is set as an end differential rotation of the cross region; The engine torque control method determines that the engine has left the cross region when the differential rotation speed reaches the final differential rotation speed.

4. 2. The engine torque control method according to claim 1, The controller: The engine torque control method includes increasing the engine torque change rate in the cross region as the accelerator opening or the accelerator opening change rate increases.

5. 2. The engine torque control method according to claim 1, The engine torque control method, wherein the predetermined torque is at least large enough to maintain the input rotation speed when the input rotation speed enters the cross region.

6. 2. The engine torque control method according to claim 1, The controller: The engine torque control method comprises: making the engine torque change rate in the cross region smaller as the gear ratio of the automatic transmission increases or as the vehicle speed increases.

7. An engine torque control device for controlling engine torque of a vehicle including an internal combustion engine, an automatic transmission, and a torque converter with a lock-up function disposed between the internal combustion engine and the automatic transmission, When the torque converter is in a non-lockup state and the running state of the vehicle is switched from a driven state to a driving state, a differential rotation acquisition unit that acquires a differential rotation between an input rotation speed and an output rotation speed of the torque converter; an in-side determination unit that determines whether or not a magnitude of a shock generated by a collision between drive train gears accompanying a change in the running state has entered a cross region, which is a range having sensitivity to a rate of change in engine torque; a torque control unit that reduces the engine torque to a predetermined torque when the engine torque enters the cross region, and suppresses the shock by limiting the engine torque change rate from that torque until the differential rotation leaves the cross region; An engine torque control device comprising:

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