JP5742790B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly, to a control device for an internal combustion engine that reduces the output torque of the drive source when shifting to a fuel cut during deceleration of the internal combustion engine that constitutes the drive source.

  2. Description of the Related Art Conventionally, a fuel cut control device (control device for an internal combustion engine) for an internal combustion engine that reduces the output torque of the drive source at the time of shifting to fuel cut during deceleration of the internal combustion engine that constitutes the drive source is known (for example, Patent Document 1).

  Conventionally, in a vehicle equipped with an internal combustion engine as a driving source, when the output torque of the internal combustion engine is not required at the time of deceleration such as when the accelerator operation is turned off by the driver, The fuel cut (fuel cut) for stopping the fuel supply is controlled.

  In the vehicle as described above, when the fuel cut is executed, the output torque output from the internal combustion engine before the fuel cut is executed (before the start) and the output torque output from the internal combustion engine after the fuel cut is executed. A shock (vibration) was generated in the vehicle.

  In addition, as an example of control for suppressing the occurrence of a shock in the vehicle, a fuel cut unit that cuts off fuel supply to the internal combustion engine when a predetermined deceleration operation condition is satisfied, and a fuel cut by the fuel cut unit is started at a predetermined level. A fuel cut delay means for delaying the time and an ignition timing delay means for retarding the ignition timing during the fuel cut delay time are known.

  With the above configuration, the output torque of the internal combustion engine is attenuated by gradually retarding the ignition timing before the fuel cut is performed, and the output torque output by the internal combustion engine before the fuel cut is performed and the fuel cut This reduces the difference from the output torque output by the internal combustion engine after execution of the control, and suppresses the occurrence of shock in the vehicle.

Japanese Patent Laid-Open No. 10-30477

  By the way, in Patent Document 1, it is possible to suppress the occurrence of a shock in the vehicle before and after the execution of the fuel cut. On the other hand, the shock occurs in the vehicle at the time of shifting to the fuel cut at the time of deceleration. Until now, it is considered that the occurrence of the shock cannot be suppressed accurately.

  That is, at the time of shifting to the fuel cut at the time of deceleration when the accelerator operation is turned off by the driver, at a certain point, from the driving state where the driving wheel is driven by the output torque generated on the output shaft of the internal combustion engine, from the driving wheel Switching to the driven state in which the output shaft of the internal combustion engine is driven by the input rotational torque. When the driving state is switched to the driven state, if there is a step between the output torque generated on the output shaft of the internal combustion engine and the rotational torque from the driving wheel, a shock (vibration) is generated in the vehicle.

  Therefore, as an example of control for suppressing the shock of the vehicle at the time of shifting to the fuel cut at the time of deceleration, from when the fuel cut execution condition is satisfied prior to the fuel cut execution (start) until the fuel cut is executed The period of time (the transition time to fuel cut) is divided into a plurality of periods, and control for gradually decreasing the torque in each period has been proposed.

  In this control, the drive wheels of the vehicle are rotationally driven by the first period from when the fuel cut execution condition is satisfied to when the control for reducing the output torque of the drive source is executed (started), and by the output torque of the internal combustion engine. A second period, and a third period in which the driving state in which the driving wheels of the vehicle are rotationally driven by the output torque of the internal combustion engine is switched to a driven state in which the output shaft of the internal combustion engine is rotationally driven by the rotational torque of the driving wheels; The fuel at the time of deceleration is controlled by performing torque control so that the output shaft of the drive source is rotationally driven by the rotational torque of the drive wheel and the torque is reduced to a predetermined magnitude for each period. It is possible to suppress the occurrence of shock (vibration) in the vehicle at the time of shifting to the cut.

  In the above control, if the torque gradient in the second period is smaller than the torque gradient in the third period (the torque gradient in the second period <the torque gradient in the third period), When switching to the third period, a shock (vibration) may occur in the vehicle due to a steep torque gradient (a large torque change). For this reason, by increasing (longening) the time in the third period, the torque gradient in the third period is moderated, and a shock (vibration) is generated in the vehicle when switching from the second period to the third period. Is suppressed.

  However, by increasing (lengthening) the time of the third period, it is possible to suppress the occurrence of shock (vibration) in the vehicle, while the amount of time for the third period is increased (longer). ), There is a problem that the time (delay time) until the fuel cut is performed (started) becomes long.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress the occurrence of shock (vibration) in the vehicle when shifting to fuel cut during deceleration. An object of the present invention is to provide a control device for an internal combustion engine that can improve fuel consumption.

  As means for solving the above-mentioned problems, a control device for an internal combustion engine according to the present invention is configured as follows.

That is, the control apparatus for an internal combustion engine according to the present invention is premised on a configuration in which the output torque of the drive source is reduced when the internal combustion engine constituting the drive source shifts to fuel cut during deceleration. In the control device for an internal combustion engine according to the present invention, a period from the time when the fuel cut execution condition is satisfied to the time when a specified delay time has elapsed is defined as a first period, and from the end of the first period , An output torque of the internal combustion engine that switches from a driving state in which the driving wheels of the vehicle are rotated by the output torque of the internal combustion engine to a driven state in which the output shaft of the internal combustion engine is rotationally driven by the rotational torque of the driving wheels of the vehicle. A period from when the output torque of the internal combustion engine decreases to a torque higher than a certain “drive / driven switching torque” by a predetermined constant is defined as a second period, and from the end of the second period , the period until the time when the output torque of the internal combustion engine decreases to a predetermined constant fraction lower torque than the driven switching torque "and the third period, the end of the third period From the time, when the output torque of the internal combustion engine until said predetermined output torque at the end of the control to decrease the output torque of the internal combustion engine is the period a fourth period until the time of the reduction, when the second period ends And the second torque based on the torque at the end of the second period and the torque at the end of the third period. When the slope of the first torque is smaller than the slope of the second torque, the third period is omitted and control is performed so as to shift to the fourth period. .

  According to the control apparatus for an internal combustion engine having such a configuration, the slope of the first torque calculated based on the torque at the end of the second period and the torque at the end of the fourth period is the torque at the end of the second period. When the slope of the second torque calculated based on the torque at the end of the third period is smaller than the third period, the third period is omitted. Therefore, the fuel cut execution condition is satisfied by the amount of the third period omitted. Then, the time from when the fuel cut is performed can be shortened. Further, since the output torque of the drive source can be reduced (attenuated) so as to satisfy the gradient condition of the first torque having a smaller gradient than the second torque within the fourth period after the end of the second period. The output torque of the drive source can be gradually reduced (damped) within the fourth period in which the restriction and the inclination of the torque are given. As a result, fuel consumption is improved by reducing the time (delay time) until fuel cut is performed while suppressing the occurrence of shock (vibration) in the vehicle when shifting to fuel cut during deceleration. can do.

  As specific configurations of the present invention, the following plural ones are listed.

In the control apparatus for an internal combustion engine according to the present invention, preferably, when the slope of the first torque is larger than the slope of the second torque, the process shifts to the third period to reduce the output torque of the internal combustion engine. Control is performed so as to shift to the fourth period after the output torque of the internal combustion engine has decreased to a predetermined output torque at the end of the control. According to this configuration, when the slope of the first torque is larger than the slope of the second torque, the output torque of the drive source reaches a predetermined magnitude in the third period without omitting the third period. Since it is decreased (attenuated), it is possible to suppress deterioration in drivability due to a large torque change when switching from the second period to the third period.

  In the control device for an internal combustion engine according to the present invention, it is preferable that a value obtained by subtracting the torque at the end of the fourth period from the torque at the end of the second period is the third torque from the torque at the end of the second period. The third period is omitted when the value obtained by subtracting the torque at the end of the period is smaller than the value obtained by adding a predetermined determination constant and the gradient of the first torque is smaller than the gradient of the second torque. Then, control is performed so as to shift to the fourth period. If comprised in this way, based on the magnitude | size of a predetermined determination constant, it can be judged easily whether a 3rd period is abbreviate | omitted and it transfers to a 4th period.

  In the control device for an internal combustion engine according to the present invention, it is preferable that the slope of the first torque is a value obtained by subtracting the torque at the end of the fourth period from the torque at the end of the second period. The slope of the second torque is calculated by dividing the torque at the end of the second period from the torque at the end of the third period by the elapsed time of the third period. It is calculated by dividing. If comprised in this way, the inclination of 1st torque and the inclination of 2nd torque can be calculated easily. Thus, by comparing the magnitude of the first torque inclination and the magnitude of the second torque inclination, it is possible to easily determine whether or not to shift to the fourth period by omitting the third period.

  The control apparatus for an internal combustion engine according to the present invention can improve fuel efficiency while suppressing the occurrence of shock (vibration) in the vehicle at the time of shifting to fuel cut during deceleration.

1 is a diagram illustrating a schematic configuration of a vehicle according to an embodiment of the present invention. It is the schematic which shows the control block of an engine. It is a flowchart which shows an example of the control which ECU performs at the time of transfer to the fuel cut at the time of deceleration. It is a time chart which shows both the case where a 3rd period is abbreviate | omitted at the time of transfer to the fuel cut at the time of deceleration, and a 3rd period is not abbreviate | omitted. It is a time chart which shows both the case where a 3rd period by the modification of one Embodiment of this invention is abbreviate | omitted and transfers to a 4th period, and the case where a 3rd period is not abbreviate | omitted.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Engine-
In the present embodiment, a case where the present invention is applied to a vehicle (automobile) equipped with a multi-cylinder (for example, four-cylinder) gasoline engine will be described. First, a schematic configuration of a vehicle 100 equipped with an engine (internal combustion engine) 1 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, a vehicle 100 according to this embodiment includes an engine 1 that constitutes a drive source, a torque converter 101 that amplifies output torque output from the engine 1, and a rotational speed of an output shaft of the torque converter 101. The transmission mechanism 103 that rotates the output shaft 102 at the changed rotational speed, the differential gear 105 that transmits the rotational force of the output shaft 102 of the transmission mechanism 103 to the drive shafts 104R and 104L, and the drive shafts 104R and 104L are rotated. Driving wheels 106R and 106L driven by Here, the torque converter 101 and the speed change mechanism 103 constitute an automatic transmission 107.

  The engine 1 includes a cylinder block 11 having cylinder bores 11a for four cylinders (only one cylinder is shown in FIG. 1), and a cylinder head 12. Each cylinder bore 11a is provided with a piston 13 configured to be able to move up and down. The piston 13 is connected to a crankshaft 15 that is an output shaft of the engine 1 via a connecting rod (connecting rod) 14. A combustion chamber 16 is defined by a space surrounded by the piston 13 and the cylinder head 12 inside the cylinder bore 11a.

  A spark plug (a spark plug) 2 is attached to the cylinder head 12 corresponding to each combustion chamber 16. The cylinder head 12 is provided with an intake port 12a and an exhaust port 12b that communicate with each combustion chamber 16, respectively. An intake passage 3 and an exhaust passage 4 are connected to the intake port 12a and the exhaust port 12b, respectively.

  An intake valve 31 and an exhaust valve 41 are provided at each open end leading to the combustion chamber 16 in the intake port 12a and the exhaust port 12b. The intake valve 31 and the exhaust valve 41 are opened and closed by an intake camshaft 32 and an exhaust camshaft 42 that are respectively rotated by the power of the crankshaft 15. The power of the crankshaft 15 is transmitted to the intake camshaft 32 and the exhaust camshaft 42 via the timing belt 15a, the timing pulley 33, and the timing pulley 43.

  Further, in the vicinity of the intake port 12a, a fuel injection valve (injector) 5 is provided corresponding to each cylinder. Each injector 5 is supplied with fuel at a predetermined pressure via a fuel supply system.

  On the other hand, a surge tank 34 is provided in the intake passage 3. On the upstream side of the surge tank 34, a throttle valve 36 whose opening degree is adjusted by driving a throttle motor 36a is provided. The intake air amount introduced into the intake passage 3 is adjusted according to the opening of the throttle valve 36. Furthermore, an air cleaner 37 for purifying the intake air is provided on the upstream side of the throttle valve 36.

  When the operation of the engine 1 is started, the intake air is introduced into the intake passage 3 and fuel is injected from the injector 5, whereby the intake air and the fuel are mixed to form an air-fuel mixture. In the intake stroke of the engine 1, the intake port 12a is opened by the intake valve 31, whereby the air-fuel mixture is taken into the combustion chamber 16 through the intake port 12a.

  The air-fuel mixture taken into the combustion chamber 16 is compressed in the compression stroke, and then ignited by the spark plug 2. The air-fuel mixture explodes and burns, and a driving force is applied to the crankshaft 15 (expansion stroke). The exhaust gas after combustion is discharged to the exhaust passage 4 (exhaust stroke) by opening the exhaust port 12b by the exhaust valve 41, further purified through the catalyst 44, and then released to the outside. The spark plug 2 executes an ignition operation for the air-fuel mixture in accordance with the application timing of the high voltage output from the igniter 21.

-ECU-
The operating state of the engine 1 is controlled by an ECU (Electronic Control Unit) 6. As shown in FIG. 2, the ECU 6 includes a CPU (Central Processing Unit) 61, a ROM (Read Only Memory) 62, a RAM (Random Access Memory) 63, a backup RAM 64, and the like.

  The ROM 62 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 61 executes arithmetic processing based on various control programs and maps stored in the ROM 62.

  The RAM 63 is a memory that temporarily stores calculation results in the CPU 61, data input from each sensor, and the like. The backup RAM 64 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped. The CPU 61, ROM 62, RAM 63, and backup RAM 64 are connected to each other via a bus 67, and are connected to an external input circuit 65 and an external output circuit 66.

The external input circuit 65 includes an accelerator opening sensor 70, a water temperature sensor 71, an air flow meter 72, an intake air temperature sensor 73, an O ₂ sensor 74, a throttle position sensor 75, a crank angle sensor 76, a cam angle sensor 77, a knock sensor 78, and An intake pressure sensor 79 is connected to each other. On the other hand, the external output circuit 66 is connected to the injector 5, the igniter 21, and a throttle motor 36a for driving the throttle valve 36 (see FIG. 1).

  As shown in FIG. 1, the accelerator opening sensor 70 detects the opening (operation amount) of the accelerator pedal 35 operated by the driver, and transmits the opening signal to the ECU 6. The water temperature sensor 71 detects the temperature of the cooling water flowing in the water jacket 11 b formed in the cylinder block 11 and transmits the cooling water temperature signal to the ECU 6. The air flow meter 72 detects the intake air amount and transmits the intake air amount signal to the ECU 6.

The intake air temperature sensor 73 is provided integrally with the air flow meter 72, detects the intake air temperature, and transmits the intake air temperature signal to the ECU 6. The O ₂ sensor 74 detects the oxygen concentration in the exhaust, determines whether or not the air-fuel ratio in the exhaust is at the stoichiometric air-fuel ratio, and transmits a determination signal to the ECU 6. The throttle position sensor 75 detects the opening of the throttle valve 36 and transmits a throttle opening detection signal to the ECU 6.

  The crank angle sensor 76 is disposed in the vicinity of the crankshaft 15 and detects the rotation angle (crank angle CA) and the rotation speed (engine speed Ne) of the crankshaft 15. Specifically, the crank angle sensor 76 outputs a pulse signal at every predetermined crank angle (for example, 30 °). As an example of a crank angle detection method by the crank angle sensor 76, external teeth are formed every 30 ° on the outer peripheral surface of the rotor (NE rotor) integrally rotated with the crankshaft 15, and the external teeth face each other. A crank angle sensor 76 made of an electromagnetic pickup is disposed. The crank angle sensor 76 generates an output pulse when the external teeth pass in the vicinity of the crank angle sensor 76 as the crankshaft 15 rotates. In addition, as this NE rotor, the thing in which the external teeth formed in an outer peripheral surface are formed every 10 degrees may be applied. In this case, frequency division is performed in the ECU 6 to generate output pulses every 30 ° CA.

  The cam angle sensor 77 is disposed in the vicinity of the intake camshaft 32, and is used as a cylinder discrimination sensor by outputting a pulse signal corresponding to the compression top dead center (TDC) of the first cylinder, for example. . That is, the cam angle sensor 77 outputs a pulse signal for each rotation of the intake camshaft 32. As an example of the cam angle detection method by the cam angle sensor 77, external teeth are formed at one place on the outer peripheral surface of the rotor integrally formed with the intake camshaft 32, and the external teeth are opposed to each other by an electromagnetic pickup. The cam angle sensor 77 is configured to generate an output pulse when the external teeth pass in the vicinity of the cam angle sensor 77 as the intake camshaft 32 rotates. Since this rotor rotates at half the rotational speed of the crankshaft 15, an output pulse is generated every time the crankshaft 15 rotates 720 °. In other words, an output pulse is generated each time a specific cylinder reaches the same stroke (for example, when the first cylinder reaches compression top dead center).

  The knock sensor 78 is a vibration sensor that detects the vibration of the engine transmitted to the cylinder block 11 by a piezoelectric element type (piezo element type) or an electromagnetic type (magnet, coil). The intake pressure sensor 79 is provided in the surge tank 34, detects the pressure in the intake passage 3 (intake pipe pressure), and transmits the intake pressure signal to the ECU 6.

  Further, as part of engine control, the ECU 6 performs a fuel cut that stops the fuel supply to the engine 1 when the vehicle 100 is decelerated. In the present embodiment, the ECU 6 controls each part such as the igniter 21, the injector 5, and the throttle motor 36a based on the output signals of the various sensors 70 to 79, so that the fuel cut at the time of deceleration of the engine 1 described later is performed. At the time of transition, control for decreasing (attenuating) the output torque (engine shaft torque) of the engine 1 is executed. Further, when the engine shaft torque is reduced (attenuated), the ECU 6 acquires the magnitude (torque value) of the engine shaft torque and performs control for determining the transition period based on the inclination of the engine shaft torque. The magnitude (torque value) of the engine shaft torque is estimated from the operating state of the engine 1 and is obtained by referring to a map stored in advance in the ROM 62 based on, for example, the rotational speed Ne of the engine 1 or the intake air amount. It is done. Hereinafter, the “control for determining the transition period” will be described in detail.

-Control for determining transition period by ECU6-
FIG. 3 is a flowchart illustrating an example of control for determining a transition period executed by the ECU 6 when shifting to a fuel cut during deceleration according to the present embodiment. 4 and 5 are time charts showing an example of control for determining a transition period executed by the ECU 6 at the time of transition to fuel cut during deceleration. 4 and 5, the vertical axis represents the engine shaft torque (the output torque of the engine 1), and the horizontal axis represents the elapsed time.

  In the present embodiment, as shown in FIG. 4, the control for reducing the output torque (engine shaft torque) of the engine 1 at the time of shifting to the fuel cut at the time of deceleration is usually performed in four periods (first period, second period). , The third period and the fourth period).

  The first period is a period from time t1 to time t2. Time t1 is the time when the driver turns off the accelerator operation and the time when the fuel cut execution condition is satisfied. Time t2 is a point in time when a specified delay time has elapsed from time t1. In the first period, preparations (preparation for performing control for determining the transition period) are performed until the control for reducing the engine shaft torque is started after the fuel cut execution condition is satisfied. The delay time is set so that the above preparation can be completed with certainty.

  The second period is a period from time t2 to time t3. This second period is a period during which the drive wheels 106R and 106L of the vehicle 100 are rotationally driven by the engine shaft torque after the end of the first period. Time t3 indicates a point in time immediately before the power transmission state of the vehicle 100 is switched from the driving state to the driven state. Note that the time t3 immediately before the switching is a torque (torque at the start of the third period) that is higher by a predetermined constant than the driving / driven switching torque that is an estimated value (set value) of the engine shaft torque at the time of switching. ) Until the engine shaft torque decreases. In the second period, control is performed to attenuate the engine shaft torque by an integral multiple of the natural vibration period of the drive system within the time calculated from the map.

  The third period is a period from time t3 to time t31. In the third period, the output shaft of the engine 1 is driven by the rotational torque of the driving wheels 106R and 106L of the vehicle 100 from the driving state in which the driving wheels 106R and 106L of the vehicle 100 are rotationally driven by the output torque of the engine 1 after the end of the second period. This is a period during which the (crankshaft 15) is switched to a driven state in which it is rotationally driven. Time t31 indicates a time immediately after the power transmission state of the vehicle 100 is switched from the driving state to the driven state. It should be noted that the time immediately after the switching is the time when the engine shaft torque has decreased to a torque lower than the driving / driven switching torque by a predetermined constant (torque at the end of the third period). Further, the torque at the start of the third period and at the end of the third period surely falls within the range of “driving / driven switching torque ± (predetermined constant)” regardless of individual differences of the vehicle 100 and changes with time. Thus, the driving / driven switching torque is set. Further, in the third period, the shock (vibration) generated in the vehicle 100 is suppressed by restricting the gradient of the engine shaft torque (the torque gradient condition is satisfied).

  The fourth period is a period from time t31 to time t41. This is a period in which the output shaft of the engine 1 is rotationally driven by the rotational torque of the drive wheels 106R and 106L of the vehicle 100 after the end of the third period. Time t41 indicates the time point when the engine shaft torque is reduced to the engine shaft torque (torque before F / C) at the end of the control for decreasing the engine shaft torque. That is, the engine shaft torque at the time of shifting to the fuel cut at the time of deceleration is controlled so as to decrease to the torque before F / C (torque before fuel cut). In the fourth period, control is performed to attenuate the engine shaft torque by an integral multiple of the natural vibration period of the drive system within the time calculated from the map. Then, after time t41, fuel cut is performed (started).

  In the present embodiment, as shown in FIG. 4, a case where the engine shaft torque when the driver's accelerator is OFF at time t1 is relatively low will be described. In this case, the gradient of the engine shaft torque in the second period is smaller than the gradient of the torque in the third period, and the magnitude of the torque at the end of the third period is relatively close to the magnitude of the pre-F / C torque. ing.

  In this embodiment, as an example of the control for determining the transition period when shifting to the fuel cut at the time of deceleration, at the end of the second period (time t3), first, the torque at the end of the second period (third The slope of the first torque is calculated based on the torque at the start of the period) and the torque at the end of the fourth period (torque before F / C). Next, the slope of the second torque is calculated based on the torque at the end of the second period (torque at the start of the third period) and the torque at the end of the third period. And when it is judged that the inclination of the 1st torque is smaller than the inclination of the 2nd torque, control which omits the 3rd period and shifts to the 4th period is performed. That is, after the end of the second period, the fourth period (the third and fourth integration periods shown in FIG. 4) is started, and in the fourth period (the third and fourth integration periods shown in FIG. 4), the slope of the first torque Control is performed to reduce (attenuate) the engine shaft torque so as to satisfy the condition. This “control for omitting the third period and shifting to the fourth period” will be described in detail below with reference to the flowchart shown in FIG. 3 and the time charts shown in FIGS. 4 and 5.

  First, when the opening degree (operation amount) of the accelerator pedal 35 operated by the driver is detected and it is determined that the opening degree of the accelerator pedal is in the OFF state, control for determining this transition period is started ( Time t1 (accelerator OFF) shown in FIG.

  As shown in FIG. 3, in step ST1, the output torque (engine shaft torque) of the engine 1 is attenuated in the first period. Thereafter, the process proceeds to step ST2, where it is determined whether or not the current timing is the end timing of the first period (time t2), and this process is repeated until it is determined that it is the end timing of the first period (No) Determination: No). If it is determined in step ST2 that it is the end timing (time t2) of the first period (positive determination: Yes), the process proceeds to step ST3.

  In step ST3, in the second period (period from time t2 to time t3), the output torque (engine shaft torque) of the engine 1 is attenuated by the time determined from the map stored in the ROM 62. Thereafter, the process proceeds to step ST4, where it is determined whether or not the current timing is the end timing of the second period (time t3), and this process is repeated until it is determined that it is the end timing of the second period (No) Determination: No). In step ST4, when it is determined that it is the end timing (time t3) of the second period (Yes determination: Yes), the process proceeds to step ST5. Note that the end timing (time t3) of the second period is the time when the engine shaft torque has decreased to the torque at the start of the third period.

  In step ST5, {(torque at the end of the second period) − (torque before F / C)} is {(torque at the start of the third period) − (torque at the end of the third period) + determination constant α}. It is determined whether or not it is smaller. That is, as shown in FIG. 4, it is determined whether the torque T1 is smaller than the torque T2. The determination constant α is whether or not the third period is omitted and the process proceeds to the fourth period in step ST8 described later (whether or not the third period and the fourth period are integrated into the fourth period). The determination constant can be arbitrarily set (adjusted). For example, when the determination constant α is set to a relatively small value (a value smaller than the value obtained by subtracting the pre-F / C torque from the torque at the end of the third period), the torque T1 becomes larger than the torque T2. In step ST5, a negative determination (No) is made. If the determination constant α is set to a relatively large value (a value larger than the value obtained by subtracting the pre-F / C torque from the torque at the end of the third period), the torque T1 becomes smaller than the torque T2, and therefore the step In ST5, an affirmative determination (Yes) is made.

  In step ST5, {(torque at the end of the second period) − (torque before F / C)} is {(torque at the start of the third period) − (torque at the end of the third period) + determination constant α. }, The process proceeds to step ST6. If the determination in step ST5 is negative (No), the process proceeds to step ST12.

  In step ST6, a map or the like is referred to based on the torque at the end of the second period (torque at the start of the third period) and the torque at the end of the fourth period (torque before F / C). The slope (solid line shown in FIG. 4) is calculated. Specifically, as shown in FIG. 4, the slope of the first torque is the torque at the end of the second period (time) when the fourth period starts after the third period is omitted after the end of the second period. The value obtained by subtracting the torque at the end of the fourth period (third and fourth integration period) (the torque “C before F / C at time t4)” from the torque “A” at the start of the third period at t3) This is a value divided by four periods (third and fourth integration periods: time t3 to time t4). The length of the third and fourth integration periods (time t3 to time t4) is substantially the same as the length of the fourth period (time t31 to time t41) before the third period is omitted.

  In step ST7, the slope of the second torque (the broken line shown in FIG. 4) is referred to with reference to a map or the like based on the torque at the end of the second period (torque at the start of the third period) and the torque at the end of the third period. ) Is calculated. Specifically, when the third period starts after the end of the second period, the slope of the second torque is determined from the torque at the end of the second period (torque “A” at the start of the third period at time t3). This is a value obtained by subtracting the value obtained by subtracting the end of the third period (torque “B” at the end of the third period at time t31) by the third period (time t3 to time t31).

  Here, in this embodiment, in step ST8 shown in FIG. 3, it is determined whether or not the slope of the first torque is smaller than the slope of the second torque. That is, the slope of the first torque calculated in step ST6 is compared with the slope of the second torque calculated in step ST7. And when it determines with the inclination of 1st torque being smaller than the inclination of 2nd torque (affirmation determination: Yes), a process is advanced to step ST9. If it is determined in step ST8 that the slope of the first torque is greater than the slope of the second torque (negative determination: No), the process proceeds to step ST12.

  In addition, when it determines with the inclination of 1st torque being larger than the inclination of 2nd torque in step ST8 (negative determination: No), for example like the modification of this embodiment shown in FIG. For example, the torque when the accelerator is OFF is relatively high. In this case, unlike the present embodiment shown in FIG. 4, the torque gradient in the second period is larger than the torque gradient in the third period. Compared with the present embodiment shown in FIG. 4, the torque at the end of the third period is relatively far from the pre-F / C torque. As in the processes of steps ST6 and ST7, as a result of calculating the first torque and the second torque, the slope of the first torque (solid line) becomes larger than the slope of the second torque (broken line).

  If it is determined in step ST8 shown in FIG. 3 that the slope of the first torque is smaller than the slope of the second torque (Yes: Yes), the process proceeds to step ST9. In step ST9, as shown in FIG. 4, the third period is omitted and the process proceeds to the fourth period. In the fourth period (third and fourth integration periods) after the third period is omitted, the control of suppressing the shock (vibration) of the vehicle 100 by restricting the inclination of the engine shaft torque and the natural vibration period of the drive system Both control for attenuating the engine shaft torque by an integral multiple is performed. Thereafter, the process proceeds to step ST10.

  In step ST10, in the fourth period (third / fourth integration period: time t3 to time t4), the output torque of the engine 1 (engine shaft torque) is obtained from the map stored in the ROM 62, and the first torque The torque is attenuated to the pre-F / C torque so as to satisfy the inclination condition. Thereafter, the process proceeds to step ST11, and fuel cut (F / C) is started at time t4 shown in FIG. As described above, by omitting the third period, the time when the fuel cut is started is shortened by the third period (time from time t4 to time t41).

  In step ST5, {(torque at the end of the second period) − (torque before F / C)} is {(torque at the start of the third period) − (torque at the end of the third period) + determination constant. If it is determined that it is greater than α} (negative determination: No), the process proceeds to step ST12 without omitting the third period. In this case, in step ST <b> 12, the output torque (engine shaft torque) of the engine 1 is attenuated in the third period by the time determined from the map stored in the ROM 62. Then, after the engine shaft torque is attenuated to the torque at the end of the third period (time t31), the process proceeds to step ST10.

  In step ST10, in the fourth period (time t31 to time t41), the output torque (engine shaft torque) of the engine 1 is attenuated to the pre-F / C torque (time t41) for a time determined from the map stored in the ROM 62. Then, after the engine shaft torque is attenuated to the pre-F / C torque, the process proceeds to step ST11, and fuel cut (F / C) is started at time t41 shown in FIG.

  If it is determined in step ST8 that the slope of the first torque is greater than the slope of the second torque (negative determination: No), the process proceeds to step ST12. In this case, for example, when the third period is omitted and the process shifts to the fourth period, drivability deteriorates due to the steep inclination of the engine shaft torque (the torque change increases). Since there is a fear, the process proceeds to step ST12 without omitting the third period. Thereafter, the process proceeds in the order of step ST10 and step ST11 described above.

  As described above, according to the ECU 6 of the engine 1 according to the present embodiment, the effects listed below can be obtained.

  In the present embodiment, as described above, the slope of the first torque is based on the torque at the end of the second period (torque at the start of the third period) and the torque at the end of the fourth period (torque before F / C). Is calculated (step ST6), and the slope of the second torque is calculated based on the torque at the end of the second period (torque at the start of the third period) and the torque at the end of the third period (step ST7). When the slope of the first torque is smaller than the slope of the second torque, the third period is omitted and the process proceeds to the fourth period (step ST8, step ST9). Thus, the gradient of the first torque calculated based on the torque at the end of the second period and the torque at the end of the fourth period is based on the torque at the end of the second period and the torque at the end of the third period. Since the third period is omitted when the slope of the calculated second torque is smaller than the calculated second torque, the fuel cut is executed until the fuel cut is executed after the fuel cut execution condition is satisfied. Time can be shortened. Further, in the fourth period (third and fourth integration periods) after the end of the second period, the engine shaft torque is reduced (attenuated) so as to satisfy the gradient condition of the first torque having a smaller gradient than the second torque. (See FIG. 4), the engine shaft torque is gradually decreased (damped) within the fourth period (third and fourth integration periods) in which the time constraint and the torque gradient constraint are applied. be able to. As a result, fuel consumption is improved by reducing the time (delay time) until fuel cut is performed while suppressing the occurrence of shock (vibration) in the vehicle when shifting to fuel cut during deceleration. can do.

  In the present embodiment, as described above, when the slope of the first torque is larger than the slope of the second torque, the process shifts to the third period to decrease (attenuate) the engine shaft torque to a predetermined magnitude. After that, the process proceeds to the fourth period (step ST8, step ST12). Thereby, when the slope of the first torque is larger than the slope of the second torque, the engine shaft torque is reduced (attenuated) to a predetermined magnitude in the third period without omitting the third period. Deterioration of drivability due to an increase in torque change when switching from the second period to the third period can be suppressed.

  In the present embodiment, as described above, the value obtained by subtracting the torque at the end of the fourth period (torque before F / C) from the torque at the end of the second period (torque at the start of the third period) is Smaller than the value obtained by subtracting the torque at the end of the third period from the torque at the end of the second period (torque at the start of the third period) (step ST5), and the first torque Is smaller than the gradient of the second torque, the third period is omitted and the process proceeds to the fourth period (steps ST8 and ST9). Thereby, based on the magnitude | size of the determination constant (alpha), it can be easily judged whether a 3rd period is abbreviate | omitted and it transfers to a 4th period.

In the present embodiment, as described above, the value obtained by subtracting the torque at the end of the fourth period (torque before F / C) from the torque at the end of the second period (torque at the start of the third period) The slope of the first torque is calculated by dividing the elapsed time of four periods (time t3 to time t4) (step ST6), and the third period is calculated from the torque at the end of the second period (torque at the start of the third period). The slope of the second torque is calculated by dividing the value obtained by subtracting the torque at the end by the elapsed time (time t3 to time t31) of the third period (step ST7). Thereby, the inclination of the first torque and the inclination of the second torque can be easily calculated. As a result, by comparing the magnitude of the slope of the first torque and the magnitude of the slope of the second torque, it is possible to easily determine whether or not to shift to the fourth period while omitting the third period.
-Other embodiments-
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above embodiment, the case where the present invention is applied to a vehicle (automobile) equipped with a four-cylinder engine (internal combustion engine) has been described, but the present invention is not limited to this. In the present invention, the present invention can be applied to a vehicle (automobile) equipped with an engine (internal combustion engine) having a number of cylinders other than four cylinders.

  In the above embodiment, the slope of the first torque is obtained by subtracting the torque at the end of the fourth period from the torque at the end of the second period, and the third period is omitted after the end of the second period. Although an example is shown in which the calculation is performed by dividing by the fourth period in the case of starting, the present invention is not limited to this. In the present invention, any method other than the above may be used as long as the slope of the first torque is calculated based on the torque at the end of the second period and the torque at the end of the fourth period.

  Further, in the above embodiment, the second torque slope is obtained by subtracting the torque at the end of the third period from the torque at the end of the second period, and the third period starts after the end of the second period. Although the example calculated by dividing by 3 periods was shown, this invention is not limited to this. In the present invention, any method other than the above may be used as long as it calculates the slope of the second torque based on the torque at the end of the second period and the torque at the end of the third period.

  Moreover, although the example which calculates the inclination of 2nd torque after calculating the inclination of 1st torque was shown in the said embodiment, this invention is not limited to this. For example, the slope of the first torque may be calculated after calculating the slope of the second torque.

  INDUSTRIAL APPLICABILITY The present invention can be used for an internal combustion engine control device, and more specifically, the internal combustion engine control device reduces the output torque of the drive source when the internal combustion engine constituting the drive source shifts to fuel cut during deceleration. Can be used.

1 engine (internal combustion engine)
6 ECU (control device)
100 Vehicle 106R, 106L Driving wheel

Claims (4)

In the control device for an internal combustion engine that reduces the output torque of the drive source when shifting to the fuel cut at the time of deceleration of the internal combustion engine constituting the drive source,
A period from the time when the fuel cut execution condition is satisfied to the time when the specified delay time has elapsed is defined as a first period,
The driven shaft in which the output shaft of the internal combustion engine is rotationally driven by the rotational torque of the driving wheel of the vehicle from the driving state in which the driving wheel of the vehicle is rotationally driven by the output torque of the internal combustion engine from the end of the first period A period from when the output torque of the internal combustion engine decreases to a torque that is higher by a predetermined constant than the “drive / driven switching torque” that is the output torque of the internal combustion engine that switches to a state ,
A period from the end of the second period to a point when the output torque of the internal combustion engine decreases to a torque lower by a predetermined constant than the “drive / driven switching torque” is defined as a third period.
When the period from the end of the third period to the time when the output torque of the internal combustion engine decreases to the predetermined output torque at the end of the control for reducing the output torque of the internal combustion engine is set as the fourth period,
The slope of the first torque is calculated based on the torque at the end of the second period and the torque at the end of the fourth period, and the torque at the end of the second period and the torque at the end of the third period The slope of the second torque is calculated based on
The control apparatus for an internal combustion engine, wherein when the slope of the first torque is smaller than the slope of the second torque, the third period is omitted and control is performed so as to shift to the fourth period. The control apparatus for an internal combustion engine according to claim 1,
When the slope of the first torque is larger than the slope of the second torque , the internal combustion engine shifts to the third period and reaches the predetermined output torque at the end of control for reducing the output torque of the internal combustion engine. A control apparatus for an internal combustion engine, wherein control is performed so as to shift to the fourth period after the output torque of the engine decreases. The control apparatus for an internal combustion engine according to claim 1 or 2,
A value obtained by subtracting the torque at the end of the fourth period from the torque at the end of the second period is set to a value obtained by subtracting the torque at the end of the third period from the torque at the end of the second period. When the slope of the first torque is smaller than the added value and the slope of the second torque is smaller, the third period is omitted and control is performed to shift to the fourth period. A control device for an internal combustion engine characterized by the above. The control device for an internal combustion engine according to any one of claims 1 to 3,
The slope of the first torque is calculated by dividing a value obtained by subtracting the torque at the end of the fourth period from the torque at the end of the second period by the elapsed time of the fourth period,
The slope of the second torque is calculated by dividing a value obtained by subtracting the torque at the end of the third period from the torque at the end of the second period by the elapsed time of the third period. A control device for an internal combustion engine.

Images