JP5672250B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that performs fuel cut during deceleration.

  2. Description of the Related Art Conventionally, a vehicle equipped with an internal combustion engine as a driving force source has been known that includes a control device that performs fuel cut control for stopping the supply of fuel to the internal combustion engine during deceleration in order to improve fuel efficiency.

  When this fuel cut control is executed, there is a step in the magnitude of the output torque generated by the internal combustion engine before and after the start of the fuel cut execution, causing a shock to the vehicle and causing the driver to feel uncomfortable. . Therefore, in a control device for an internal combustion engine, the output torque is controlled before the start of the fuel cut control so as to suppress the occurrence of a shock in the vehicle due to the change in the output torque generated by the internal combustion engine at the start of the fuel cut. Is known (see, for example, Patent Document 1).

  The conventional control device described in Patent Document 1 includes a fuel cut means for cutting fuel supply to an internal combustion engine when a predetermined deceleration operation condition is satisfied, and a fuel for delaying the start of fuel cut by the fuel cut means for a predetermined time. Cut delay means and ignition timing retarding means for retarding the ignition timing during the fuel cut delay time are provided.

  This not only reduces the output torque by fully closing the throttle valve during deceleration, but also reduces the output torque by retarding, thus reducing the torque step at the start of fuel cut and causing a shock to the vehicle Was supposed to suppress.

Japanese Patent Laid-Open No. 10-030477

  However, in the conventional control device described in Patent Document 1 as described above, the time for attenuating the output torque is not considered. That is, when the vehicle transitions from the driven state to the driven state, the torsional torque between the internal combustion engine and the driving wheels is released and torsional vibration occurs, but the time from when the attenuation of the output torque starts until it ends Depending on the relationship with the period of torsional vibration, the amplitude of torsional vibration increases, so-called squealing that causes the vehicle to vibrate in the front-rear direction occurs, and drivability may be reduced.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a control device for an internal combustion engine that can suppress the occurrence of longitudinal vibrations of the vehicle during deceleration and suppress a decrease in drivability. And

  In order to achieve the above object, an internal combustion engine control apparatus according to the present invention includes: (1) an internal combustion engine control apparatus that controls the output torque of an internal combustion engine during driven driving of the vehicle. Load prediction means for predicting the engine load after a predetermined time based on the amount of change in the engine load at the time of shifting to the engine, and the engine speed of the internal combustion engine when the vehicle shifts from the driving state to the driven state And target torque calculation means for calculating a target torque after the predetermined time based on the engine load predicted by the load prediction means, and the output torque of the internal combustion engine after the predetermined time is the target torque. Control means for controlling the internal combustion engine to attenuate the output torque so as to achieve the target torque calculated by the calculation means.

  With this configuration, since the current output torque can be attenuated to the target torque over a predetermined time, the output torque can be attenuated at a desired attenuation speed. Therefore, it suppresses the occurrence of longitudinal vibrations such as sneezing in the vehicle due to the output torque decay speed not being the desired speed or changing the damping speed during the damping, thereby preventing a decrease in drivability. be able to.

  In the control device for an internal combustion engine according to (1), (2) the predetermined time is an integral multiple of a period of torsional vibration that occurs when the vehicle transitions from a driving state to a driven state. It is characterized by.

  With this configuration, the output torque can be attenuated to the target torque in a time that is an integral multiple of the torsional vibration period. As a result, it is possible to suppress an increase in the amplitude of torsional vibration due to the attenuation of the output torque. Therefore, when the output torque is attenuated, it is possible to suppress the occurrence of longitudinal vibration such as squealing in the vehicle and to prevent the drivability from being lowered.

  Further, in the control device for an internal combustion engine according to the above (1) or (2), (3) the control means attenuates the output torque by shifting the ignition timing in the combustion stroke of the internal combustion engine to the retard side. It is characterized by that.

  With this configuration, the output torque can be attenuated by controlling the ignition timing to the retard side. Thereby, the time responsiveness with respect to control of output torque can be improved. Therefore, the output torque can be adjusted with high accuracy.

  Further, in the control device for an internal combustion engine according to the above (1) to (3), (4) misfire limit torque calculation for calculating a misfire limit torque according to the most retarded ignition timing at which no misfire occurs in the internal combustion engine. And the target torque calculating means replaces the misfire limit torque with the target torque when the calculated target torque is smaller than the misfire limit torque calculated by the misfire limit torque calculating means. To do.

  With this configuration, when the target torque is lower than the misfire limit torque, the misfire limit torque can be set to the target torque. As a result, the output torque is reduced to the misfire limit torque while the output torque is being attenuated, and the attenuation rate of the output torque is prevented from changing before the predetermined time elapses, and the torsional vibration can be prevented from being amplified.

  In the control device for an internal combustion engine according to (1) to (4), (5) the control means sets the start time of the fuel cut as the end time of the predetermined time.

  With this configuration, the fuel cut control can be started in a state in which the generation of torsional vibrations is suppressed, and a decrease in drivability can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can suppress that the longitudinal vibration of a vehicle generate | occur | produces at the time of deceleration, and can suppress the fall of drivability can be provided.

It is a schematic block diagram which shows the vehicle carrying the control apparatus which concerns on embodiment of this invention. 1 is a skeleton diagram showing a configuration of a control device for an internal combustion engine according to an embodiment of the present invention. It is a graph which shows the scooping resulting from torsional vibration. It is a flowchart for demonstrating the torque damping control process which concerns on embodiment of this invention. It is a figure which shows the misfire limit ignition timing map which concerns on embodiment of this invention. It is a figure which shows the MBT illustration torque map which concerns on embodiment of this invention. It is a figure which shows the MBT ignition timing map which concerns on embodiment of this invention. It is a figure which shows the ignition timing efficiency map which concerns on embodiment of this invention. It is a timing chart for demonstrating torque damping control which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a vehicle equipped with a control device according to an embodiment of the present invention. FIG. 2 is a skeleton diagram showing a configuration around the control device for an internal combustion engine according to the embodiment of the present invention. In the present embodiment, a case where the control device for an internal combustion engine according to the present invention is applied to an FR (Front engine Rear drive) vehicle will be described.

  As shown in FIGS. 1 and 2, the vehicle 1 changes the rotational speed of the engine 2 constituting the internal combustion engine, the torque converter 3 that increases the rotational torque output by the engine 2, and the output shaft of the torque converter 3. The rotational torque output from the output shaft 46 of the transmission mechanism 4 is transmitted to the drive wheels via a differential gear (not shown).

  As will be described later, the engine 2 is configured by a known power device that outputs power by burning fuel such as gasoline. The torque converter 3 and the transmission mechanism 4 constitute an automatic transmission 5.

  As shown in FIGS. 1 and 2, the torque converter 3 is disposed between the engine 2 and the transmission mechanism 4, and is connected to the engine 2 via the input shaft 34, and the transmission mechanism 4. The turbine impeller 37 is connected through an output shaft 36 that constitutes a part of the input shaft, and the stator impeller 39 is prevented from rotating in one direction by a one-way clutch 38. The pump impeller 35 and the turbine impeller 37 transmit power through a fluid. Further, the input shaft 34 and the output shaft 36 of the torque converter 3 are connected to the pump impeller 35 and the turbine impeller 37, respectively.

  Further, the torque converter 3 includes a lockup clutch 40 for directly connecting the pump impeller 35 and the turbine impeller 37, and the lockup clutch 40 is illustrated by hydraulic oil when the vehicle 1 travels at a high speed. By grasping the front cover not to be engaged and mechanically directly connecting the pump impeller 35 and the turbine impeller 37, the power transmission efficiency from the engine 2 to the speed change mechanism 4 is increased as compared with the released state. It is like that. As will be described later, the torque converter 3 takes a slip state in which the lock-up clutch 40 slips at a predetermined slip rate when the vehicle speed, the engine speed, or the turbine speed satisfies a predetermined condition. ing.

  Further, the pump impeller 35 is provided with a mechanical oil pump 41 that generates a hydraulic pressure for controlling the transmission of the transmission mechanism 4 and a hydraulic pressure for supplying lubricating oil to each part.

  The transmission mechanism 4 includes a first planetary gear device 42, a second planetary gear device 43, and a third planetary gear device 44. The sun gear S1 of the first planetary gear unit 42 can be connected to the input shaft via the clutch C3 and can be connected to the housing 45 via the one-way clutch F2 and the brake B3.

  The carrier CA1 of the first planetary gear device 42 can be connected to the housing 45 via the brake B1. The ring gear R1 of the first planetary gear device 42 is connected to the ring gear R2 of the second planetary gear device 43, and can be connected to the housing 45 via the brake B2. The sun gear S2 of the second planetary gear device 43 is connected to the sun gear S3 of the third planetary gear device 44, and can be connected to the input shaft via the clutch C4. The sun gear S2 can be connected to the input shaft via the one-way clutch F4 and the clutch C1.

  The carrier CA2 of the second planetary gear unit 43 is connected to the ring gear R3 of the third planetary gear unit 44, and can be connected to the input shaft via the clutch C2 and to the housing 45 via the brake B4. It has become. The carrier CA2 is prevented from rotating in the direction opposite to the rotation direction of the input shaft by a one-way clutch F3 provided in parallel with the brake B4. Further, the carrier CA3 of the third planetary gear device 44 is connected to the output shaft 46.

  The vehicle 1 further includes a hydraulic pressure control circuit 6 for controlling the torque increase ratio by the torque converter 3 and the gear position of the transmission mechanism 4 by hydraulic pressure. The hydraulic control circuit 6 includes transmission solenoids S1 to S4, linear solenoids SLT and SLU, and an AT oil temperature sensor 32 for measuring the oil temperature of the hydraulic oil.

  The engine 2 includes a plurality of cylinders that form combustion chambers, and an air-fuel mixture in which air and fuel are mixed is supplied to each combustion chamber via an intake port. Each combustion chamber is provided with a spark plug having an electrode made of platinum or an iridium alloy. The spark plug is discharged when the electrode is energized at a predetermined timing by the ECU 10 and ignites the air-fuel mixture in the combustion chamber. Further, as will be described later, the ECU 10 adjusts the output torque of the engine 2 by retarding or advancing the ignition timing by the spark plug from a predetermined timing.

  The vehicle 1 further includes an intake pipe 71 for introducing air outside the vehicle into the engine 2. The intake pipe 71 has a throttle valve 31 for adjusting the flow rate of the air and an operating state of the engine 2. It has an ISC (Idle Speed Control) bypass passage 73 for adjusting the flow rate of air supplied to the engine 2 in the idling state. The ISC bypass passage 73 is provided with an ISC valve for adjusting the air flow rate. The ISC valve is driven by an ISC valve actuator controlled by the ECU 10 to change the flow rate in the ISC bypass passage 73.

  When the engine 2 is in an idle operation state, the ECU 10 fully closes the throttle valve 31 and executes ISC control described later to adjust the opening of the ISC valve. Therefore, air necessary for combustion in the idle state is supplied to the engine 2 via the ISC bypass passage 73.

  The vehicle 1 further includes an engine speed sensor 21 for measuring the engine speed ne of the engine 2, an intake air quantity sensor 22 for measuring the intake air quantity of the engine 2, and a torque connected to the turbine impeller 37. The rotational speed of the turbine rotational speed sensor 23 for measuring the rotational speed of the output shaft 36 of the converter 3, the throttle opening degree sensor 24 for measuring the opening degree of the throttle valve 31, and the rotational speed of the output shaft 46 of the transmission mechanism 4. A vehicle speed sensor 25 for measuring the vehicle speed based on the above, a cooling water temperature sensor 26 for measuring the cooling water temperature of the engine 2, and a brake sensor 27 for measuring the depression force on the brake pedal are provided. The vehicle 1 further includes a shift lever 28, an operation position sensor 29 for detecting the position of the shift lever 28, and an accelerator opening sensor 30 for measuring the accelerator opening.

  The engine speed sensor 21 measures the speed of the engine 2 based on the rotation of a crankshaft (not shown).

  The throttle opening sensor 24 is composed of, for example, a Hall element that can obtain an output voltage corresponding to the throttle opening of the throttle valve 31 and outputs a signal representing the throttle opening of the throttle valve 31 to the ECU 10 described later. It has become.

  The vehicle speed sensor 25 outputs a signal representing the vehicle speed to the ECU 10 to be described later based on the output shaft rotation speed of the automatic transmission 5.

  The brake sensor 27 measures a change in the master cylinder pressure or an operation stroke corresponding to the driver's operation pedaling force with respect to the brake pedal, and an electric signal corresponding to the measured pedaling force will be described later as a brake pedaling force signal. It outputs to ECU10.

  The operation position sensor 29 detects the operation position of the shift lever 28 operated by the driver.

  The accelerator opening sensor 30 is constituted by, for example, an electronic position sensor using a hall element, and when the accelerator pedal mounted on the vehicle 1 is operated by the driver, the accelerator opening indicated by the position of the accelerator pedal is indicated. A signal indicating the degree is output to the ECU 10 described later.

  The vehicle 1 further includes an ECU (Electronic Control Unit) 10 as an electronic control device. In the present embodiment, the ECU 10 includes an engine ECU 11 for electrically controlling the engine 2 and a transmission ECU 12 for electrically controlling the automatic transmission 5.

  The ECU 10 has a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output interface (not shown) so that the engine 2 is controlled according to the operation amount of the accelerator pedal. An engine control signal is output to the engine 2.

  The ECU 10 also includes an engine speed sensor 21, an intake air amount sensor 22, a turbine speed sensor 23, a throttle opening sensor 24, a vehicle speed sensor 25, a coolant temperature sensor 26, a brake sensor 27, an operation position sensor 29, and an accelerator opening. These sensors are connected to the sensors 30, and from these sensors, signals representing the engine speed, intake air amount, turbine speed, throttle opening, vehicle speed, cooling water temperature, brake pedaling force, shift lever 28 operating position and accelerator opening are output. Each is to be entered.

  Further, based on these signals, the ECU 10 controls the hydraulic control circuit 6 so that the engagement state of the lockup clutch 40 in the torque converter 3 and the gear position in the transmission mechanism 4 are controlled. Further, the ROM of the ECU 10 stores a map representing a shift diagram based on the vehicle speed and the throttle opening, a program for executing shift control, and the like.

  Further, the ECU 10 may have an automatic shift mode for selecting a shift speed according to the traveling state of the vehicle 1 and a manual shift mode for selecting a shift speed according to a manual operation. Here, the traveling state of the vehicle 1 means states such as the speed of the vehicle 1, the throttle opening, the coolant temperature, and the AT oil temperature.

  As will be described later, the ECU 10 constitutes an internal combustion engine control device, load prediction means, target torque calculation means, misfire limit torque calculation means, and control means according to the present invention.

  Hereinafter, a characteristic configuration of the ECU 10 constituting the control device for an internal combustion engine according to the embodiment of the present invention will be described with reference to the drawings.

  The ECU 10 constituting the control device for an internal combustion engine according to the present invention calculates a target torque after a predetermined time when the vehicle 1 is switched from a driving state to a driven state, so that the current torque becomes the calculated target torque. It is designed to attenuate at a constant speed.

  Specifically, when the ECU 10 acquires a signal indicating that the accelerator opening is "0" from the accelerator opening sensor 30, the ECU 10 determines the current engine load kl and the engine based on the intake air amount detected by the intake air amount sensor 22. The load change amount dlkl is calculated. The relationship between the intake air amount and the engine load kl is stored in advance in the ROM as a map.

  Further, the ECU 10 calculates a predicted value prekl of the engine load after the squeezing suppression time T4 set in advance based on the natural vibration period of the torsional vibration in order to suppress the squealing caused by the torsional vibration of the vehicle 1. It is supposed to be. Therefore, the ECU 10 according to the present embodiment constitutes a load prediction unit according to the present invention, and the squealing suppression time T4 means a predetermined time according to the present invention.

  Torsional vibration is vibration that occurs when the torsion generated in the output shaft 46 of the automatic transmission 5 and the drive shaft that transmits power to the drive wheels during the traveling of the vehicle 1 is released. It has a unique vibration period determined by the specification values. The amplitude of the torsional vibration changes according to the relationship between the engine torque decay time and the vibration period. When the engine torque decay time is an integral multiple of the vibration period of the torsional vibration, the torsional vibration amplitude is minimized. Become. In other words, when the engine torque decay time is set in the vicinity of an integral multiple of the torsional vibration period, the increase in the torsional vibration amplitude can be suppressed as shown by the thin line in FIG. If the vibration period becomes other than an integral multiple of the torsional vibration period or the damping speed changes in the middle, as shown by a thick line in FIG. 3, the torsional vibration becomes larger in amplitude.

  As an example, a description will be given using a spring mass model representing a displacement x of an object when an external force F (t) is applied to an object of mass m connected to a spring having a spring constant k.

It is assumed that the following external force is applied to the object according to time t.
F (t) = 0 (t <0) (1)
F (t) = P / t ₁ · t (0 <t <t ₁ ) (2)
F (t) = P (t ₁ <t) (3)

ここで、ωは、ばね定数および物体の質量から求められる固有振動数に対応した角速度であり、ｘ_ｓｔは、入力Ｐに対する静的変位である。 In this case, the displacement x of the object at t ₁ <t is expressed by the following formula (4).

Here, ω is an angular velocity corresponding to the natural frequency obtained from the spring constant and the mass of the object, and x _st is a static displacement with respect to the input P.

  When the equation (4) is differentiated by t and the time t when the velocity of the object becomes 0, that is, the time t when the displacement becomes maximum is obtained from the equation (5), the equation (6) is obtained.

cos ω (t−t ₁ ) −cos ωt = 0 (5)
_{t = t 1/2 + nπ} / ω (6)

式（７）に表されるように、物体に式（２）により表される外力が加わる場合、ｔ_１を固有振動数の整数倍にすると、物体の最大変位ｘ_ｍａｘが静的変位ｘ_ｓｔと等しくなる。したがって、しゃくり抑制時間Ｔ４を捩れ振動の振動周期の整数倍にし、このしゃくり抑制時間Ｔ４に合わせてエンジントルクを減衰することにより、車両１にしゃくりを発生させることなく正味トルクを減衰することが可能となる。 Therefore, at the time t in the equation (6), the maximum value x _max of the displacement of the object is expressed by the following equation (7).

As expressed in Expression (7), when an external force expressed by Expression (2) is applied to the object, if t ₁ is an integer multiple of the natural frequency, the maximum displacement x _{max of the} object becomes the static displacement x _st Is equal to Therefore, the net torque can be attenuated without causing the vehicle 1 to squeak by making the squealing suppression time T4 an integral multiple of the torsional vibration period and attenuating the engine torque in accordance with this squeezing suppression time T4. It becomes.

  In addition, since there are a plurality of members that generate torsion, the degree to which the amplitude of torsional vibration is actually attenuated varies depending on how many times the vibration suppression period T4 is increased. . Therefore, based on the simulation results and the experimental results, the number of times the squeezing suppression time T4 is set to the vibration period is set.

  Further, the ECU 10 calculates a target net torque after the squeezing suppression time T4 has elapsed based on the current engine speed ne and the predicted engine load value Prekl. Therefore, the ECU 10 according to the present embodiment constitutes a target torque calculation unit according to the present invention. A method for calculating the target net torque will be described later.

  When the target net torque is smaller than the misfire limit torque, the actual net torque decreases to the misfire limit torque before the sneezing suppression time T4 elapses, and then the net torque value is misfired until the end of the sneezing suppression time T4. The limit torque will be maintained. That is, the net torque decay time is shorter than the squeezing suppression time T4, and as a result, the possibility of sneezing occurs. Therefore, the ECU 10 calculates the misfire limit ignition timing, as will be described later, based on the current engine speed ne and the calculated predicted engine load value prekl.

  Then, the ECU 10 calculates the misfire limit torque as described later based on the current engine speed ne, the calculated predicted value of the engine load prekl and the misfire limit ignition timing. Therefore, the ECU 10 according to the present embodiment constitutes a misfire limit torque calculating means according to the present invention. If the ECU 10 determines that the target net torque is smaller than the misfire limit torque, the ECU 10 replaces the misfire limit torque with the target net torque. As a result, the ECU 10 prevents the net torque from falling below the misfire limit torque before the sneezing suppression time T4 elapses.

  Further, the ECU 10 controls the engine 2 so that the current engine torque (net torque) is attenuated to the target net torque by the squeezing suppression time T4. Therefore, the ECU 10 according to the present embodiment constitutes a control means according to the present invention.

  In the present embodiment, the ECU 10 attenuates engine torque by retarding the ignition timing of each combustion stroke.

  The ECU 10 calculates the net torque by subtracting the friction torque and the auxiliary machine torque from the indicated torque. Here, the friction torque represents the torque consumed by the frictional force generated between the members inside the engine 2 and is obtained in advance by experimental measurement. The auxiliary machine torque represents torque consumed by driving auxiliary machines such as an air conditioner and an alternator. The ECU 10 calculates the auxiliary machine torque according to the operating status of the air conditioner and the alternator. For example, a map representing the magnitude of the auxiliary torque according to the operating status of each auxiliary machine is stored in the ROM in advance. In addition, the auxiliary machine torque is calculated by referring to this map.

  Next, torque attenuation control processing according to the present embodiment will be described with reference to FIG.

  The following processing is executed at predetermined time intervals by the CPU constituting the ECU 10 on the condition that the accelerator opening is in a fully closed state, and realizes a program that can be processed by the CPU.

  First, when a signal indicating accelerator OFF is input from the accelerator opening sensor 30, the ECU 10 calculates the current engine load kl and the engine load change amount dlkl (step S11). In the present embodiment, the ECU 10 calculates the engine load based on the intake air amount.

  Next, the ECU 10 determines whether or not the vehicle 1 is in a driven state (step S12). Specifically, the ECU 10 determines that the vehicle 1 is in a driven state when the net torque of the engine 2 becomes equal to or less than a predetermined value. This predetermined value is determined from the differential gear from the engine 2 based on, for example, the running resistance of the vehicle 1 or the gear ratio corresponding to the gear stage formed in the automatic transmission 5, the gear ratio of the differential gear, the output torque of the engine, and the like. Is calculated in advance as a value obtained by subtracting the offset amount TQOFS from a value etq1 that balances the net torque transmitted to the drive wheel and the torque transmitted from the drive wheel to the differential gear.

  If the ECU 10 determines that the vehicle 1 is in the driven state (YES in step S12), the ECU 10 proceeds to step S13. On the other hand, when it is determined that the vehicle 1 is not in the driven state (NO in step S12), the process proceeds to END.

  Next, the ECU 10 calculates a predicted value prekl of the engine load at the end of torque attenuation (step S13). Specifically, the ECU 10 refers to the squeezing suppression time T4 stored in the ROM, and based on the current engine load kl and the engine load change dlkl calculated in step S11, the lapse of the squealing suppression time T4. A predicted value prekl of the engine load later is calculated.

  Next, the ECU 10 calculates a target net torque based on the current engine speed ne and the predicted value prekl of the engine load (step S14). Specifically, the current engine speed ne is calculated based on a signal input from the engine speed sensor 21. Then, the target torque is calculated using the engine speed ne, the predicted engine load value prekl calculated in step S13, and the target torque calculation map stored in the ROM. The target torque calculation map associates the engine speed ne and the predicted engine load value prekl with the target net torque, and is generally defined such that the smaller the predicted engine load value prekl, the smaller the target net torque. Yes.

  Note that the current engine speed ne is used because the squeezing suppression time T4 is as short as several hundred milliseconds and the lockup clutch 40 is in an engaged state. This is because the rotational speed ne becomes substantially the same value.

  Next, the ECU 10 calculates the misfire limit ignition timing based on the current engine speed ne and the predicted value prekl of the engine load. (Step S15). Specifically, the ECU 10 calculates the misfire limit ignition timing using the current engine speed ne, the predicted engine load value prekl, and the misfire limit ignition timing map shown in FIG. The misfire limit ignition timing map associates the engine speed ne and engine load kl with the misfire limit ignition timing. The lower the engine load and the higher the engine speed, the more the misfire limit ignition timing is advanced. On the side. It is preferable to use the value calculated in step S14 as the engine speed ne.

  Next, the ECU 10 calculates a misfire limit torque based on the current engine speed ne, the predicted value of the engine load prekl, and the misfire limit ignition timing calculated in step S15 (step S16). Specifically, the ECU 10 calculates MBT (Minimum Advance for Best Torque) indicated torque at the time point of the sneezing suppression time T4 based on the engine speed ne, the predicted value of engine load prekl and the MBT indicated torque map. As shown in FIG. 6, the MBT indicated torque map is obtained by associating the engine speed ne, the engine load, and the MBT indicated torque, and is defined so that the MBT indicated torque increases as the engine load increases. .

  Further, based on the engine speed ne, the predicted engine load value prekl, and the MBT ignition timing map, the MBT ignition timing at the elapsed time of the sneezing suppression time T4 is calculated. As shown in FIG. 7, the MBT ignition timing map associates the engine speed ne, the engine load, and the MBT ignition timing. The lower the engine load and the higher the engine speed, the more the MBT ignition timing. It is defined on the advance side.

  Next, the efficiency is calculated based on the ignition timing efficiency map corresponding to the calculated MBT ignition timing and the misfire limit ignition timing calculated in step S15. The ignition timing efficiency map is created for each MBT ignition timing, and as shown in FIG. 8, the ignition timing and the efficiency are associated with each other. Further, the efficiency at the MBT ignition timing is defined to be 1.0. Then, the ECU 10 calculates the misfire limit torque from the product of the MBT indicated torque and the efficiency.

  Next, the ECU 10 compares the target net torque calculated in step S14 with the misfire limit torque calculated in step S16 (step S17).

  If the ECU 10 determines that the target net torque is equal to or greater than the misfire limit torque (NO in step S17), the ECU 10 proceeds to step S19. On the other hand, if it is determined that the target net torque is smaller than the misfire limit torque (YES in step S17), the process proceeds to step S18.

  When the process proceeds to step S18, the ECU 10 replaces the misfire limit torque with the target net torque. In other words, the ECU 10 replaces the value of the target net torque so that the target net torque does not become smaller than the misfire limit torque, and the net torque reaches the misfire limit torque during execution of the torque attenuation process, that is, in the middle of the sneezing suppression time T4. Prevents the decay rate from changing.

  Next, the ECU 10 executes the retard angle control for the engine 2 so that the current net torque is attenuated to the target net torque at a constant speed during the squeezing suppression time T4 (step S19). It should be noted that the start time of the squeezing suppression time T4 means the time when the ECU 10 determines that the driven state is in the driven state as described above, that is, the time when the net torque becomes etq1-TQOFS.

  Specifically, the ECU 10 calculates the decay rate of the net torque by dividing the difference between the current net torque and the target net torque by the squeezing suppression time T4, and ignites the combustion stroke of each cylinder according to the number of cylinders. The required net torque at the timing is calculated. The current net torque is calculated by calculating the MBT indicated torque from the current engine speed ne, the engine load kl, and the MBT indicated torque map (see FIG. 6), the MBT ignition timing map (see FIG. 7), and the ignition timing efficiency. The efficiency is calculated from the map (see FIG. 8), the current indicated torque is calculated from the product of the calculated MBT indicated torque and the efficiency, and the friction torque and the auxiliary machine torque are subtracted from the indicated torque.

  Based on the current engine speed ne, the estimated load prekl11 at the next ignition timing, and the calculated required net torque, the ignition timing at the next ignition timing is calculated. The estimated load prekl1 at the next ignition timing is calculated from the calculated engine load change amount dlkl and the time until the next ignition timing. The ignition timing is calculated based on the MBT indicated torque map (see FIG. 6), the MBT ignition timing map (see FIG. 7), and the ignition timing efficiency map (see FIG. 8), similarly to the above-described target ignition timing calculation. Is called. The ECU 10 corrects the ignition timing in the cylinder at which the next ignition timing occurs according to the difference between the current net torque obtained from the current engine speed ne and the engine load kl and the required net torque.

  Then, the ECU 10 continues to calculate the ignition timing in step S19 until the squeezing suppression time T4 elapses, and performs retardation control based on the ignition timing calculated for each ignition timing of the combustion stroke. Then, the ECU 10 starts the fuel cut control after the squeezing suppression time T4 has elapsed.

  A torque attenuation control process executed in the control apparatus configured as described above will be described with reference to a timing chart shown in FIG. In FIG. 10, a solid line represents each characteristic when torque damping control according to the present embodiment is executed, and a broken line represents each characteristic when conventional torque control is executed.

  First, at time t1, the accelerator opening becomes 0 (solid line 87), and the engine speed decreases (solid line 81). Next, at time T3 from time t2 to time t3, the vehicle 1 shifts from the driving state to the driven state. Further, the ECU 10 calculates the predicted value prekl of the engine load after the sneezing suppression time T4 has elapsed based on the change amount of the engine load at the present time (solid line 84).

  Thus, the engine torque can be attenuated at a constant speed during the squeezing suppression time T4 (see the solid line 82). Further, even when the fuel cut (F / C) is started at time t5 after the sneezing suppression time T4 has elapsed, the vehicle 1 is not squeezed, and drivability can be improved.

  On the other hand, in the conventional torque attenuation control process, the prediction value prekl of the engine load is not calculated at the time t3. Therefore, for example, even if the target ignition timing after the squeezing suppression time T4 has been set based on the engine load at time t3 and the current ignition timing is controlled to become the target ignition timing during the squeezing suppression time T4, As indicated by the ignition timing 90, the ignition timing may be retarded from the misfire limit ignition timing (see broken line 86). In this case, the time until the ignition timing reaches the misfire limit ignition timing is shorter than the squeezing suppression time T4 (see the broken line 83), resulting in squealing and resulting in a decrease in drivability (see the broken line 89). ).

  As described above, since the ECU 10 according to the embodiment of the present invention can attenuate the current output torque to the target torque over a predetermined time, the output torque can be attenuated at a desired attenuation rate. . Therefore, it suppresses the occurrence of longitudinal vibrations such as sneezing in the vehicle due to the output torque decay speed not being the desired speed or changing the damping speed during the damping, thereby preventing a decrease in drivability. be able to.

  Further, the ECU 10 can attenuate the output torque to the target torque during a time that is an integral multiple of the torsional vibration period. As a result, it is possible to suppress an increase in the amplitude of torsional vibration due to the attenuation of the output torque. Therefore, when the output torque is attenuated, it is possible to suppress the occurrence of longitudinal vibration such as squealing in the vehicle and to prevent the drivability from being lowered.

  Further, the ECU 10 can attenuate the output torque by controlling the ignition timing to the retard side. Thereby, the time responsiveness with respect to control of output torque can be improved. Therefore, the output torque can be adjusted with high accuracy.

  Further, when the target net torque is lower than the misfire limit torque, the ECU 10 can set the misfire limit torque to the target net torque. As a result, the output torque is reduced to the misfire limit torque while the output torque is being attenuated, and the attenuation rate of the output torque is prevented from changing before the predetermined time elapses, and the torsional vibration can be prevented from being amplified.

  Further, the ECU 10 can start the fuel cut control in a state in which the occurrence of torsional vibration is suppressed, and can suppress a decrease in drivability.

  In the above description, the ECU 10 has been described with respect to the case where the magnitude of the net torque is controlled so that the damping speed of the output torque of the engine 2 is constant during the squeezing suppression time T4. However, the ECU 10 may cause the ignition timing to shift to the retard side at a constant speed during the squeezing suppression time T4.

  In this case, although there is a possibility that the amplitude of the torsional vibration becomes larger than when the damping speed of the output torque is made constant, the ECU 10 can more easily realize the torque damping control process.

  Specifically, in step S14, the ECU 10 calculates the target ignition timing at the elapsed time of the squeezing suppression time T4 instead of calculating the target net torque based on the current engine speed ne and the predicted engine load value prekl. calculate. Then, the ECU 10 retards the ignition timing at a constant speed so that the current ignition timing becomes the target ignition timing when the squeezing suppression time T4 elapses.

  Further, the ECU 10 calculates the misfire limit ignition timing in the same manner as in step S15. When the target ignition timing is retarded from the misfire limit ignition timing, the ECU 10 replaces the misfire limit ignition timing with the target ignition timing. .

  As described above, the control device for an internal combustion engine according to the present invention has the effect of suppressing the occurrence of longitudinal vibration of the vehicle during deceleration and suppressing the decrease in drivability. This is useful for a control device for an internal combustion engine to be executed.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 3 Torque converter 4 Transmission mechanism 5 Automatic transmission 6 Hydraulic control circuit 10 ECU (Control device, load prediction means, target torque calculation means, misfire limit torque calculation means, control means)
DESCRIPTION OF SYMBOLS 21 Engine speed sensor 22 Intake air amount sensor 23 Turbine speed sensor 24 Throttle opening sensor 25 Vehicle speed sensor 29 Operation position sensor 30 Accelerator opening sensor 31 Throttle valve 34 Input shaft 36 Output shaft 46 Output shaft 71 Intake pipe

Claims (5)

In a control device for an internal combustion engine that controls the output torque of the internal combustion engine when the vehicle is driven,
Load prediction means for predicting the engine load after a predetermined time based on the amount of change in the engine load when the vehicle transitions from the driven state to the driven state;
Based on the engine speed of the internal combustion engine when the vehicle transitions from the driving state to the driven state and the engine load after the predetermined time predicted by the load prediction means, the target torque after the predetermined time Target torque calculation means for calculating
Control means for controlling the internal combustion engine so as to attenuate the output torque so that the output torque of the internal combustion engine becomes the target torque calculated by the target torque calculation means after the predetermined time. Control device.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the predetermined time is an integral multiple of a period of torsional vibration that occurs when the vehicle shifts from a driving state to a driven state.   The control device for an internal combustion engine according to claim 1 or 2, wherein the control means attenuates the output torque by shifting the ignition timing in the combustion stroke of the internal combustion engine to the retard side. A misfire limit torque calculating means for calculating a misfire limit torque according to the most retarded ignition timing at which no misfire occurs in the internal combustion engine;
The target torque calculation means replaces the misfire limit torque with the target torque when the calculated target torque is smaller than the misfire limit torque calculated by the misfire limit torque calculation means. The control device for an internal combustion engine according to any one of claims 3 to 3.   The control device for an internal combustion engine according to any one of claims 1 to 4, wherein the control means sets a start time of the fuel cut as an end time of the predetermined time.

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