JP4702563B2 - Powertrain control device - Google Patents

Description

  The present invention relates to a powertrain control device that transmits engine output to a wheel side via a torque converter with a lock-up clutch and a speed change mechanism having a plurality of speed stages.

  In a vehicle equipped with an engine, when the throttle opening is on a fully closed coast (in coastal running) and the engine speed is within a predetermined fuel cut region (region above the predetermined fuel cut return rotational speed), There is a fuel cut control that stops fuel injection to improve fuel efficiency.

Further, in order to lengthen the duration of the fuel cut control and enhance the fuel efficiency improvement effect, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2005-98522), the slip amount of the lockup clutch ( By controlling the rotational speed difference between the output shaft side and the input shaft side) and maintaining the lockup clutch in the engaged state or the predetermined slip state, the engine rotational speed is prevented from abruptly decreasing and the engine rotational speed is fuel cut. In some cases, the speed change mechanism is downshifted to a shift stage on the side of increasing the speed ratio so as to maintain the range.
JP-A-2005-98522 (second page, etc.)

  However, as in the technique of Patent Document 1 described above, if the speed change mechanism is downshifted to a gear position on the gear ratio increase side so as to maintain the engine speed in the fuel cut region during coasting, the engine brake increases, so There is concern that the deceleration of the engine rotation after the shift increases and unintended sudden deceleration occurs. In particular, when the slip amount of the lock-up clutch is controlled to prevent engine stall (so-called engine stall), it is possible to maintain the engine speed in the fuel cut region up to a lower vehicle speed region, but by that amount, the speed is changed more. Downshifting to a gear ratio with a large ratio will cause a significant increase in deceleration due to an increase in engine brake, which may deteriorate drivability.

  The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to maintain the engine speed in the fuel cut region while controlling the slip amount of the lockup clutch during the deceleration operation. An object of the present invention is to provide a powertrain control device that can prevent unintentional sudden deceleration when downshifting the speed change mechanism and can achieve both fuel efficiency and drivability.

In order to achieve the above object, an invention according to claim 1 is directed to a powertrain control device that transmits engine output to a wheel side via a torque converter with a lock-up clutch and a transmission mechanism having a plurality of shift stages. , The fuel injection of the engine is stopped when the engine speed is in the range above the predetermined fuel cut return speed (hereinafter referred to as the “fuel cut range”) during the deceleration operation with the accelerator opening fully closed by the fuel cut control means In addition, the lockup clutch control means controls the slip amount of the lockup clutch during the deceleration operation, and the downshift control means controls the speed change mechanism to maintain the engine speed in the fuel cut region during the deceleration operation. Downshifting to the increasing gear and further decelerating by engine brake correction means It is obtained so as to correct the engine braking force to suppress the increase in the engine braking force after downshift as deceleration does not become excessive engine speed after the downshift of the transmission mechanism.

In this configuration, during the deceleration operation, the engine rotation speed is controlled while controlling the slip amount of the lock-up clutch so that the lock-up clutch is in the engaged state or the predetermined slip state to prevent a sudden decrease in the engine rotation speed. By downshifting the speed change mechanism so as to be maintained in the cut region, the duration of fuel cut control can be lengthened and the fuel efficiency improvement effect can be enhanced. Further, by correcting the engine braking force after the downshift so that the deceleration of the engine rotation after the downshifting of the transmission mechanism is not excessive, the increase in the engine braking force due to the downshifting of the transmission mechanism is suppressed, and after the downshifting An increase in the deceleration of the engine rotation can be suppressed. As a result, unintended sudden deceleration can be prevented and drivability can be improved.

  In this case, as in claim 2, an intake air amount adjusting means capable of adjusting the intake air amount of the engine irrespective of the accelerator opening is provided, and the intake air is adjusted so that the deceleration of the engine rotation is within a predetermined range during the deceleration operation. The engine braking force may be corrected by adjusting the intake air amount by the amount adjusting means. When the intake amount of the engine is increased, the in-cylinder negative pressure of the engine is reduced (changes in the atmospheric pressure direction) and the pumping loss is reduced. Therefore, the engine braking force is reduced accordingly. Therefore, if the intake air amount is increased by the intake air amount adjusting means, the increase in the engine brake force due to the downshift of the speed change mechanism is suppressed by the decrease in the engine brake force due to the increase in the intake air amount, and the deceleration of the engine rotation is suddenly increased. It can be controlled within a predetermined range that does not cause deceleration.

  Further, when the intake air amount is adjusted by the intake air amount adjusting means to correct the engine braking force, the intake air amount adjusting means according to the downshift destination gear stage of the speed change mechanism during the deceleration operation as in claim 3. It is better to set the control amount. In this way, the control amount of the intake air amount adjusting means is changed in response to the increase in the engine braking force due to the downshift depending on the shift stage (speed ratio) of the downshift destination of the transmission mechanism. Therefore, the amount of decrease in the engine braking force due to the increase in the intake air amount (that is, the correction amount of the engine braking force) can be set to an appropriate value.

  According to a fourth aspect of the present invention, an electronic throttle device that adjusts an opening degree of a throttle valve provided in an intake passage of an engine with an electric actuator may be used as the intake air amount adjusting means. If the electronic throttle device is used, it is possible to adjust the intake amount of the engine by adjusting the throttle opening (throttle valve opening) regardless of the accelerator opening. In this case, it is preferable that the throttle opening be increased as the gear ratio of the downshift destination is increased. As a result, the increase in the engine brake force due to the downshift increases as the gear ratio of the downshift destination gear increases, and the engine brake force decreases as the intake air amount increases by increasing the throttle opening. The increase in engine braking force due to downshifting can be reliably suppressed, and deceleration control can be executed at a moderate deceleration to a lower speed (a gear with a large gear ratio). .

  The intake air amount adjusting means is not limited to the electronic throttle device. For example, as described in claim 5, the intake air amount adjusting means adjusts the amount of air flowing by bypassing a throttle valve provided in the intake passage of the engine. It is also possible to use an idle rotation adjusting device. If the idle rotation adjusting device is used, the intake air amount of the engine can be adjusted by adjusting the amount of air flowing by bypassing the throttle valve regardless of the accelerator opening.

  Alternatively, an exhaust gas recirculation device that adjusts the exhaust gas recirculation amount to be recirculated to the intake passage of the engine may be used as the intake air amount adjusting means. If the exhaust gas recirculation device is used, it is possible to adjust the intake air amount of the engine by adjusting the exhaust gas recirculation amount that is recirculated to the intake passage of the engine regardless of the accelerator opening.

  Further, when downshifting the speed change mechanism during the deceleration operation, the speed change mechanism is downshifted at a shift timing determined by a normal shift line (for example, a line indicating a shift timing that changes according to the vehicle speed and the throttle opening). Instead, as in claim 7, the speed change mechanism is downshifted in response to a decrease in engine speed so as to maintain the engine speed in the fuel cut region (region above the fuel cut return rotational speed) during the deceleration operation. You may do it. In this way, the response delay time of the speed change mechanism (for example, the delay time from when the downshift command is generated until the speed ratio actually changes and the rotation speed of the input shaft of the speed change mechanism starts to increase) is taken into consideration. Thus, the engine speed can be increased by downshifting the speed change mechanism before the engine speed decreases to the fuel cut return speed (lower limit value of the fuel cut region). As a result, the engine speed can be reliably maintained in the fuel cut region, and the duration of fuel cut control can be reliably lengthened. In this case, it is preferable to generate a downshift command by calculating the shift timing while monitoring the actual engine speed behavior during deceleration operation, but in order to simplify the calculation process, the normal shift line is Different shift lines for extending the fuel cut period may be created in advance, and the shift timing may be determined using the shift line for extending the fuel cut period to generate a downshift command.

  In general, the response delay time of the speed change mechanism is substantially constant without depending on the engine speed, so that the greater the vehicle deceleration (that is, the greater the engine speed deceleration), the less the response delay time of the speed change mechanism. There is a tendency that the amount of decrease in the engine rotation speed increases.

  In consideration of such characteristics, the start timing of the downshift of the speed change mechanism may be set to the higher vehicle speed side as the deceleration of the vehicle is larger during the deceleration operation. In this way, as the vehicle deceleration increases (that is, the engine rotation deceleration increases), the amount of decrease in the engine rotation speed within the response delay time of the speed reduction mechanism increases. Downshift start timing can be set on the high vehicle speed side (that is, on the high rotation side), and the engine speed can be reduced by downshifting the transmission mechanism before the engine rotation speed is reliably reduced to the fuel cut return rotation speed. Can be raised.

  Further, when correcting the engine braking force during the deceleration operation, the timing or the gear ratio at which the rotational speed of the input shaft of the transmission mechanism starts to increase due to the downshift of the transmission mechanism during the deceleration operation, as in claim 9. It is preferable to start correction of the engine braking force at the timing at which the change starts. In this way, it is possible to alleviate the deceleration-side shift shock that occurs with the downshift of the transmission mechanism.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire control system of the engine 11 which is an internal combustion engine will be described with reference to FIG. An air cleaner 13 is mounted on the upstream side of the intake pipe 12 (intake passage) of the engine 11, and an air flow meter 14 for measuring the intake air amount Ga is installed on the downstream side thereof. Further, on the downstream side of the air flow meter 14, a throttle valve 16 whose opening is adjusted by an electric actuator such as a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided. An electronic throttle device 18 (intake air amount adjusting means) is provided.

  An injector 20 is attached to an intake manifold 19 that introduces intake air that has passed through the throttle valve 16 into each cylinder of the engine 11, and a spark plug 21 is attached to a cylinder head of each cylinder of the engine 11. . A crank angle sensor 24 is installed facing the outer periphery of the signal rotor 23 fitted to the crankshaft 22 of the engine 11, and a pulse of the engine rotation speed signal output from the crank angle sensor 24 is transmitted to an engine electronic control circuit (hereinafter referred to as an engine electronic control circuit). The engine rotational speed Ne is detected by the pulse frequency of the engine rotational speed signal.

  On the other hand, the depression amount (accelerator opening) of the accelerator pedal 26 is detected by the accelerator sensor 27, and a voltage signal Ap corresponding to the accelerator opening is taken into the engine ECU 25 via the A / D converter 28. Further, the intake air amount Ga detected by the air flow meter 14 and the voltage signals of the throttle opening TA detected by the throttle opening sensor 17 are also taken into the engine ECU 25 via the A / D converter 28.

  The engine ECU 25 is composed mainly of a microcomputer including a CPU 29, a ROM 30, a RAM 31, and the like, and controls various ignition control routines stored in the ROM 30 by the CPU 29, thereby controlling the ignition timing of the spark plug 21. At the same time, the pulse width of the injection signal applied to the injector 20 via the injector drive circuit 45 is controlled to control the fuel injection amount.

  In addition, the engine ECU 25 executes various throttle control routines stored in the ROM 30 by the CPU 29 so that the throttle opening detected by the throttle opening sensor 17 matches the target throttle opening. The motor 15 of the throttle valve 16 is feedback-controlled by PID control or the like via the circuit 32. When the electronic throttle system is abnormal, the safety circuit 46 provided in the energization path from the motor drive circuit 32 to the motor 15 is operated, and the energization to the motor 15 is kept off. In this state, the throttle opening is held at a predetermined opening in order to enable retreat travel.

  Next, a schematic configuration of the automatic transmission 51 will be described with reference to FIGS. As shown in FIG. 3, an input shaft 53 of a torque converter 52 is connected to the output shaft of the engine 11, and a hydraulically driven transmission gear mechanism 55 (transmission mechanism) is connected to the output shaft 54 of the torque converter 52. Has been. Inside the torque converter 52, a pump impeller 71 and a turbine runner 72 constituting a fluid coupling are provided to face each other, and a stator 73 that rectifies the flow of oil is provided between the pump impeller 71 and the turbine runner 72. It has been. The pump impeller 71 is connected to the input shaft 53 of the torque converter 52, and the turbine runner 72 is connected to the output shaft 54 of the torque converter 52.

  The torque converter 52 is provided with a lockup clutch 56 for engaging or disengaging between the input shaft 53 side and the output shaft 54 side. The output torque of the engine is transmitted to the transmission gear mechanism 55 via the torque converter 52, is shifted by a plurality of gears (such as planetary gears) of the transmission gear mechanism 55, and is transmitted to the drive wheels (front wheels or rear wheels) of the vehicle. Is done.

  The transmission gear mechanism 55 is provided with a plurality of clutches C0, C1, C2 and brakes B0, B1, which are friction engagement elements for switching a plurality of shift stages. As shown in FIG. The gear ratio is switched by switching the engagement / release of C1 and C2 and the brakes B0 and B1 by hydraulic pressure and switching the combination of gears for transmitting power.

  FIG. 4 shows a combination of engagement of the clutches C0, C1, C2 and the brakes B0, B1 of the four-speed automatic transmission, and the mark “O” is held in the engaged state (torque transmission state) at the gear stage. The clutch and brake are shown, and the unmarked state shows the released state. For example, in the throttle depression state of the D range, as the vehicle speed increases, it is upshifted to first speed, second speed, third speed, and fourth speed. In the shift from the first speed to the second speed, B0 is released from the engagement of C0 and B0, and B1 is newly engaged. In the shift from the second speed to the third speed, B1 is released from the engagement of C0 and B1, and C2 is newly engaged. In the shift from the third speed to the fourth speed, C0 is released from the engagement of C0 and C2, and B1 is newly engaged.

  As shown in FIG. 2, the transmission gear mechanism 55 is provided with a hydraulic pump 58 driven by engine power, and a hydraulic control circuit 57 is provided in an oil pan (not shown) that stores hydraulic oil (oil). Is provided. The hydraulic control circuit 57 includes a line pressure control circuit 59, an automatic transmission control circuit 60, a lock-up control circuit 61, a manual switching valve 66, and the like. The hydraulic oil pumped up from the oil pan by the hydraulic pump 58 is controlled by the line pressure. This is supplied to the automatic transmission control circuit 60 and the lockup control circuit 61 via the circuit 59. The line pressure control circuit 59 is provided with a hydraulic pressure control valve (not shown) for controlling the hydraulic pressure from the hydraulic pump 58 to a predetermined line pressure. The automatic transmission control circuit 60 includes a transmission gear mechanism. A plurality of shift hydraulic control valves (not shown) for controlling the hydraulic pressure supplied to the clutches C0, C1, C2 and the brakes B0, B1 are provided. The lockup control circuit 61 is provided with a lockup control hydraulic control valve (not shown) for controlling the hydraulic pressure supplied to the lockup clutch 56.

  Further, a manual switching valve 66 that is switched in conjunction with the operation of the shift lever 65 is provided between the line pressure control circuit 59 and the automatic transmission control circuit 60. When the shift lever 65 is operated to the neutral range (N range) or the parking range (P range), even if the energization of the hydraulic control valve of the automatic transmission control circuit 60 is stopped (OFF), The hydraulic pressure supplied to the transmission gear mechanism 55 is switched by the manual switching valve 66 so that the transmission gear mechanism 55 is in a neutral state.

  On the other hand, the transmission gear mechanism 55 includes a turbine rotation speed sensor 68 that detects a turbine rotation speed Nt that is an input shaft rotation speed of the transmission gear mechanism 55 and an output shaft rotation that detects an output shaft rotation speed No of the transmission gear mechanism 55. A speed sensor 69 is provided.

  Output signals of these various sensors are input to an automatic transmission electronic control circuit (hereinafter referred to as “AT-ECU”) 70. The AT-ECU 70 is mainly composed of a microcomputer, and executes various routines stored in a built-in ROM (storage medium), whereby a transmission gear according to a preset shift pattern shown in the shift diagram of FIG. The shift of the hydraulic control valve of the automatic shift control circuit 60 is controlled according to the operating position of the shift lever 65 and the operating conditions (throttle opening, vehicle speed, etc.) so that the shift of the mechanism 55 is executed. By controlling the hydraulic pressure applied to the clutches C0, C1, C2 and the brakes B0, B1 of the gear mechanism 55, as shown in FIG. 4, the clutches C0, C1, C2 and the brakes B0, B1 are engaged. The gear ratio of the transmission gear mechanism 55 is switched by switching the release / release and switching the combination of gears that transmit power.

  As shown in the functional block diagram of FIG. 6, the engine ECU 25 and the AT-ECU 70 function as a power train control device 74, and during the deceleration operation with the accelerator opening fully closed, the fuel control unit 75 (fuel cut control means). Thus, fuel cut control for stopping fuel injection of the injector 20 is executed when the engine rotational speed Ne is in a region that is equal to or higher than a predetermined fuel cut return rotational speed FCNe (hereinafter referred to as “fuel cut region”) to improve fuel efficiency. .

  Further, the lockup clutch engagement force control unit 76 (lockup clutch control means) is configured to detect the slip amount of the lockup clutch 56 (rotational speed difference between the output shaft 54 side and the input shaft 53 side of the torque converter 52, that is, the turbine rotational speed). Lock-up clutch slip control for maintaining the lock-up clutch 56 in the engaged state or the predetermined slip state by feedback-controlling the engaging force of the lock-up clutch 56 so that the difference between Nt and the engine speed Ne) matches the target value. And the engine speed Ne is maintained in the fuel cut region (region above the fuel cut return rotational speed FCNe) by the shift control unit 77 (downshift control means) while preventing the engine rotational speed Ne from rapidly decreasing. As described above, the gear ratio of the transmission gear mechanism 55 is set to be greater than the current gear speed Run the downshift control to downshift to deal of shift speed, the duration of the fuel cut control by lengthening enhance the fuel efficiency.

  Further, the intake control unit 78 (engine brake correcting means) adjusts the throttle opening by the electronic throttle device 18 so that the deceleration of the engine rotation after the downshift of the transmission gear mechanism 55 does not become excessive. Execute engine brake correction control to correct When the intake air amount of the engine 11 is increased, the in-cylinder negative pressure of the engine 11 decreases (changes in the atmospheric pressure direction) and the pumping loss decreases, and therefore, there is a relationship that the engine braking force decreases accordingly. Therefore, if the throttle opening is adjusted by the electronic throttle device 18 to increase the intake amount, the increase in the engine brake force due to the downshift of the transmission gear mechanism 55 is suppressed by the decrease in the engine brake force due to the increase in the intake amount. Thus, an increase in deceleration of the engine rotation can be suppressed. As a result, the deceleration of the engine rotation is controlled within a predetermined range that does not cause sudden deceleration, so that unintended sudden deceleration can be prevented and drivability can be improved.

The powertrain control (fuel cut control, lockup clutch slip control, downshift control, engine brake correction control) during deceleration operation described above is executed by the engine ECU 25 and the AT-ECU 70 according to the routines shown in FIGS. The Hereinafter, the processing content of each of these routines will be described.
[Powertrain control main routine]
The powertrain control main routine shown in FIG. 7 is executed at a predetermined cycle. When this routine is started, first, in step 101, after reading travel information (accelerator opening, throttle opening, engine speed, turbine speed, vehicle speed, etc.) based on the output of various sensors, Proceeding to 102, it is determined based on the traveling information whether the traveling state of the vehicle is an acceleration state, a steady state, or a deceleration state.

  If it is determined in step 102 that the running state of the vehicle is the acceleration state, the routine proceeds to step 103, where a powertrain control routine during acceleration operation (not shown) is executed to turn off the engine 11 and the automatic transmission 51. Control.

  If it is determined in step 102 that the running state of the vehicle is a steady state, the routine proceeds to step 104, where a powertrain control routine during steady operation (not shown) is executed, and the engine 11 or automatic transmission is executed. 51 is controlled.

If it is determined in step 102 that, for example, the accelerator opening is fully closed and the vehicle is in a decelerating state, the process proceeds to step 105, and a powertrain control routine during deceleration operation in FIG. And the engine 11 and the automatic transmission 51 are controlled.
[Powertrain control routine during deceleration operation]
The power train control routine during the deceleration operation shown in FIG. 8 is a subroutine executed in step 105 of the power train control main routine of FIG. When this routine is started, first, in step 201, fuel cut control for stopping fuel injection of the injector 20 is executed when the engine rotational speed Ne is in the fuel cut region (region where the fuel cut return rotational speed FCN is higher). .

  Thereafter, the routine proceeds to step 202, where it is determined whether or not the vehicle deceleration is suddenly decelerating to a predetermined value or more. If it is determined in step 202 that the vehicle deceleration is smaller than the predetermined value and it is not during sudden deceleration, the routine proceeds to step 203, where the slip amount of the lockup clutch 56 (turbine rotational speed Nt and engine rotational speed). A lock-up clutch slip control for feedback-controlling the engagement force of the lock-up clutch 56 so as to match the difference (Ne) with the target value and maintaining the lock-up clutch 56 in the engaged state or the predetermined slip state, A sudden decrease in the engine speed Ne is prevented.

Thereafter, the routine proceeds to step 204, where it is determined whether or not it is a shift timing (downshift start timing) depending on whether or not the engine rotational speed Ne is equal to or less than the downshift determination value. Here, the downshift determination value is the response delay time T0 of the transmission gear mechanism 55 (for example, the turbine rotation speed that is the input shaft rotation speed of the transmission gear mechanism 55 due to the actual change of the gear ratio after the downshift command is generated. Taking into account the delay time until Nt starts to increase) and the deceleration δNe of the immediately preceding engine rotation (that is, the decreasing speed of the engine rotation speed Ne), the following equation shows the higher rotation speed than the fuel cut return rotation speed FCNe The rotation speed is set.
Downshift judgment value = FCNe + δNe × T0

  Thus, during deceleration operation, the downshift determination value is set to the higher rotation side as the vehicle deceleration is larger (that is, the engine rotation deceleration δNe is larger), and the downshift of the transmission gear mechanism 55 is started. The timing is set to the high vehicle speed side (that is, the high rotation side). If it is determined in step 204 that the engine rotational speed Ne is higher than the downshift determination value, the process proceeds to step 206 without executing the downshift control (step 205).

  Thereafter, when it is determined in step 204 that the engine rotational speed Ne has decreased below the downshift determination value, the routine proceeds to step 205, where a downshift command is output to change the gear position of the transmission gear mechanism 55 to the current shift speed. Downshift control for extending the fuel cut period for downshifting to a gear stage having a larger gear ratio than the gear stage is executed. As a result, before the engine rotation speed decreases to the fuel cut return rotation speed FCNe (lower limit value of the fuel cut region), the transmission gear mechanism 55 is downshifted to increase the engine rotation speed Ne, and the engine rotation speed Ne is fueled. Maintaining in the cut region (region above the fuel cut return rotational speed FCNe), the duration of the fuel cut control is lengthened and the fuel efficiency improvement effect is enhanced.

  After that, the routine proceeds to step 206, where the turbine rotational speed Nt that is the input shaft rotational speed of the transmission gear mechanism 55 starts to increase or the gear ratio starts to change due to the downshift of the transmission gear mechanism 55 (that is, the downshift command So that the deceleration of the engine rotation after the downshift of the transmission gear mechanism 55 does not become excessive when the response delay time T0 of the transmission gear mechanism 55 has elapsed since The engine brake correction control for adjusting the engine brake force by adjusting is started.

  In this engine brake correction control, the throttle opening for engine brake correction is set according to the downshift destination gear stage of the transmission gear mechanism 55. Specifically, the throttle opening for engine brake correction increases as the gear ratio of the downshift destination gear stage increases (that is, the gear stage is downshifted from 4th speed → 3rd speed → 2nd speed → 1st speed). So that the throttle opening for engine brake correction increases). As a result, the increase in the engine brake force due to the downshift increases as the gear ratio of the downshift destination gear increases, and the engine brake force decreases as the intake air amount increases by increasing the throttle opening. The increase in the engine brake force due to the increase in the intake air amount is suppressed, and the increase in the engine brake force due to the downshift of the transmission gear mechanism 55 is suppressed, so that the deceleration of the engine rotation falls within a predetermined range that does not cause a sudden deceleration. Control.

  On the other hand, if it is determined in step 202 that the deceleration of the vehicle is a sudden deceleration of a predetermined value or more, the process proceeds to step 207, where lockup clutch release control for disconnecting the lockup clutch 56 is executed, Prevents engine stall (so-called engine stall) during sudden deceleration.

  Thereafter, the routine proceeds to step 208, and after executing a normal downshift control for outputting a downshift command and downshifting the transmission gear mechanism 55 at a shift timing determined by a normal shift line (see FIG. 5), Proceeding to step 209, normal throttle control is executed in which the electronic throttle device 18 controls the throttle opening based on the accelerator opening and the like.

  An execution example of the powertrain control during the deceleration operation described above will be described with reference to the time chart of FIG.

  First, at a time point t0 when the accelerator opening is changed to a fully decelerated operation from an acceleration operation in a state where the gear position of the transmission gear mechanism 55 is maintained at the fourth speed, the engine speed Ne is reduced to the fuel cut region (fuel cut return). The fuel cut control for stopping the fuel injection of the injector 20 at the time of the rotational speed FCN is executed to improve the fuel efficiency, and the slip amount of the lockup clutch 56 (the turbine rotational speed Nt and the engine rotational speed Ne) The lock-up clutch slip control for feedback-controlling the engaging force of the lock-up clutch 56 is executed so that the difference between the engine speed Ne and the target value coincides with the target value, thereby preventing a sudden decrease in the engine rotational speed Ne.

  The throttle opening may be controlled to the fully closed position at the time t0 when the accelerator opening reaches the fully closed deceleration operation, but the throttle opening is controlled to a slightly larger opening than the fully closed position. The engine braking force may be decreased by increasing the intake air amount.

  Thereafter, at the time t1 when the engine speed Ne drops to the downshift determination value set higher than the fuel cut return speed FCNe, a downshift command is output to change the gear stage of the transmission gear mechanism 55 to the fourth speed. Downshift control to downshift to 3rd gear from As a result, before the engine rotation speed decreases to the fuel cut return rotation speed FCNe, the transmission gear mechanism 55 is downshifted to increase the engine rotation speed Ne so that the engine rotation speed Ne is maintained in the fuel cut region. Increase the fuel efficiency by extending the control duration.

  Thereafter, at the time t2 at which the turbine rotational speed Nt starts to increase due to the downshift of the transmission gear mechanism 55 (at the time when the response delay time T0 of the transmission gear mechanism 55 has elapsed since the generation of the downshift command), The engine brake correction control for correcting the engine brake force by adjusting the throttle opening by the electronic throttle device 18 is started so that the deceleration of the engine rotation after the downshift does not become excessive. When the gear position of the transmission gear mechanism 55 is downshifted from the fourth speed to the third speed, the throttle opening is increased to an opening corresponding to the third speed to increase the intake air amount. Due to the decrease in engine brake force due to the increase in intake air amount, an increase in engine brake force due to a downshift of the transmission gear mechanism 55 is suppressed, and an increase in deceleration of engine rotation is suppressed.

  Thereafter, again, at the time t3 when the engine rotational speed Ne has decreased to the downshift determination value, downshift control is executed to downshift the gear stage of the transmission gear mechanism 55 from the third speed to the second speed, and the turbine is rotated by this downshift. At time t4 when the speed Nt starts to increase, the next engine brake correction control is started. When downshifting the gear stage of the transmission gear mechanism 55 from the 3rd speed to the 2nd speed, the throttle opening is increased to an opening corresponding to the 2nd speed to increase the intake air amount, and the engine brake due to the increase in the intake air amount. The increase in the engine braking force due to the downshift of the transmission gear mechanism 55 is suppressed by the decrease in the force, and the increase in the deceleration of the engine rotation is suppressed.

  In this way, when the transmission gear mechanism 55 is downshifted so as to maintain the engine speed Ne in the fuel cut region while controlling the slip amount of the lockup clutch 56 during the deceleration operation, the electronic throttle device 18 performs the throttle operation. By executing engine brake correction control that adjusts the opening to correct the engine brake force, an increase in engine brake force due to a downshift of the transmission gear mechanism 55 is suppressed, and an increase in deceleration of the engine rotation is suppressed. Can do. As a result, it is possible to prevent unintended sudden deceleration while enhancing the fuel efficiency improvement effect, and to improve drivability.

  In this embodiment, when the throttle opening is adjusted by the electronic throttle device 18 to correct the engine braking force, the throttle opening is increased as the gear ratio of the downshift destination is increased. Corresponding to the increase in engine brake force due to downshift as the gear ratio of the downshift destination gear increases, the throttle opening is increased to reduce the decrease in engine brake force due to the increase in intake air amount. It can be increased and set to an appropriate value, and an increase in engine braking force due to a downshift can be reliably suppressed, and the vehicle can be decelerated at an appropriate deceleration to a lower gear (a gear with a large gear ratio). Control can be executed.

  Furthermore, in this embodiment, the timing at which the turbine rotational speed Nt, which is the input shaft rotational speed of the transmission gear mechanism 55, starts to increase or the speed ratio starts to change due to the downshift of the transmission gear mechanism 55 (that is, the downshift command is Since the engine brake correction control is started at the time when the response delay time T0 of the transmission gear mechanism 55 has elapsed since the occurrence of the transmission gear mechanism 55, the deceleration-side shift shock that occurs as the transmission gear mechanism 55 is downshifted also occurs. Can be relaxed.

  Further, in this embodiment, taking into account the response delay time T0 of the transmission gear mechanism 55 and the deceleration δNe of the immediately preceding engine rotation, the rotational speed higher than the fuel cut return rotational speed FCNe is determined as a downshift determination value. (= FCNe + δNe × T0), and when the engine speed Ne drops below the downshift determination value, the downshift command is output to downshift the transmission gear mechanism 55. Therefore, the engine speed Ne Before the engine speed decreases to the fuel cut return rotational speed FCNe, the transmission gear mechanism 55 can be downshifted to increase the engine rotational speed Ne, and the engine rotational speed Ne can be reliably maintained in the fuel cut region. The duration of the cut control can be reliably increased.

  In general, the response delay time T0 of the transmission gear mechanism 55 is substantially constant without depending on the engine rotational speed Ne. Therefore, the greater the vehicle deceleration (that is, the greater the engine rotation deceleration δNe), the greater the transmission gear. There is a tendency that the amount of decrease in the engine rotation speed Ne within the response delay time T0 of the mechanism 55 becomes large.

  In consideration of such characteristics, in this embodiment, the greater the vehicle deceleration (that is, the greater the engine rotation deceleration δNe), the lower the shift determination value is set to the higher rotation side, and the transmission gear mechanism. Since the start timing of downshift of 55 is set to the high vehicle speed side (that is, the high rotation side), the greater the vehicle deceleration (that is, the greater the engine rotation deceleration δNe), the more the transmission gear mechanism 55 The downshift start timing of the transmission gear mechanism 55 can be set to the high vehicle speed side (that is, the high rotation side) in response to the increase amount of the engine rotation speed Ne within the response delay time T0. Before the engine speed Ne drops to the fuel cut return speed FCNe, the transmission gear mechanism 55 may be downshifted to increase the engine speed Ne. Kill.

  In the above embodiment, the shift timing is calculated and the downshift command is generated while monitoring the actual behavior of the engine rotational speed Ne during the deceleration operation, but in order to simplify the calculation process, A shift line for extending the fuel cut period that is different from this shift line may be created in advance, and the shift timing may be determined using the shift line for extending the fuel cut period to generate a downshift command. .

  Further, in the above embodiment, the throttle opening is adjusted by using the electronic throttle device 18 as the intake air amount adjusting means for executing the engine brake correction control for correcting the engine brake force by adjusting the intake air amount of the engine 11. Regardless, the intake amount of the engine 11 is adjusted by adjusting the throttle opening, but the intake air amount adjusting means is not limited to the electronic throttle device 18 and may be changed as appropriate.

  For example, an idle rotation adjusting device that adjusts the amount of air flowing by bypassing the throttle valve 16 may be used as the intake air amount adjusting means. If the idle rotation adjusting device is used, the intake air amount of the engine 11 can be adjusted by adjusting the amount of air flowing by bypassing the throttle valve 16 regardless of the accelerator opening.

  Alternatively, an exhaust gas recirculation device that adjusts the exhaust gas recirculation amount to be recirculated to the intake pipe 12 of the engine 11 may be used as the intake air amount adjusting means. If the exhaust gas recirculation device is used, the intake air amount of the engine 11 can be adjusted by adjusting the exhaust gas recirculation amount recirculated to the intake pipe 12 of the engine 11 regardless of the accelerator opening.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a schematic block diagram of the whole automatic transmission. It is a figure which shows typically the mechanical structure of an automatic transmission. It is a figure which shows the combination of engagement / release of clutch C0-C2 and brake B0, B1 for every gear stage. It is a shift diagram which shows an example of a shift pattern. It is a functional block diagram explaining the function as a power train control apparatus of engine ECU and AT-ECU. It is a flowchart explaining the flow of a process of a powertrain control main routine. It is a flowchart explaining the flow of a process of the powertrain control routine during a deceleration operation. It is a time chart explaining the example of execution of powertrain control during deceleration operation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 12 ... Intake pipe (intake passage), 15 ... Motor (electric actuator), 16 ... Throttle valve, 17 ... Throttle opening sensor, 18 ... Electronic throttle device (intake air amount adjusting means), 20 ... Injector, 24 ... crank angle sensor, 25 ... engine ECU, 26 ... accelerator pedal, 27 ... accelerator sensor, 51 ... automatic transmission, 52 ... torque converter, 55 ... transmission gear mechanism (transmission mechanism), 56 ... lock-up clutch, 68 ... turbine Rotational speed sensor 69 ... Output shaft rotational speed sensor, 70 ... AT-ECU, 74 ... Powertrain control device, 75 ... Fuel control unit (fuel cut control means), 76 ... Lock-up clutch engagement force control unit (lock-up clutch) Control means), 77... Shift control section (downshift control means), 78... Intake control section ( Down Jin brake correction means)

Claims (9)

In a powertrain control device for transmitting engine output to a wheel side via a torque converter with a lock-up clutch and a speed change mechanism having a plurality of speed stages,
Fuel cut control means for stopping fuel injection of the engine when the accelerator opening is in a fully closed decelerating operation and the engine rotational speed is in a region equal to or higher than a predetermined fuel cut return rotational speed (hereinafter referred to as “fuel cut region”); ,
Lock-up clutch control means for controlling the slip amount of the lock-up clutch during the deceleration operation;
Downshift control means for downshifting the speed change mechanism to a speed-change-side shift stage so as to maintain the engine speed in the fuel cut region during the deceleration operation;
Engine braking correction means for correcting engine braking force to suppress an increase in engine braking force after downshifting so that the deceleration of engine rotation after downshifting of the transmission mechanism during the deceleration operation is not excessive. A control apparatus for a power train. Intake amount adjustment means capable of adjusting the intake amount of the engine regardless of the accelerator opening,
The engine brake correcting means adjusts the intake air amount by the intake air amount adjusting means so as to correct the engine brake force so that the deceleration of the engine rotation is within a predetermined range during the deceleration operation. The powertrain control device according to claim 1.   3. The power train according to claim 2, wherein the engine brake correction unit sets a control amount of the intake air amount adjusting unit in accordance with a downshift destination shift stage of the transmission mechanism during the deceleration operation. Control device.   4. The power train control device according to claim 2, wherein the intake air amount adjusting means is an electronic throttle device that adjusts an opening degree of a throttle valve provided in an intake passage of the engine by an electric actuator. .   The power intake adjustment device according to claim 2 or 3, wherein the intake air amount adjusting means is an idle rotation adjusting device that adjusts an air amount flowing by bypassing a throttle valve provided in an intake passage of the engine. Control device.   The powertrain control device according to claim 2 or 3, wherein the intake air amount adjusting means is an exhaust gas recirculation device that adjusts an exhaust gas recirculation amount to be recirculated to an intake passage of the engine.   The downshift control means downshifts the speed change mechanism according to a decrease in the engine rotation speed so as to maintain the engine rotation speed in the fuel cut region during the deceleration operation. The control apparatus of the power train in any one of thru | or 6.   The downshift control means sets the start timing of the downshift of the speed change mechanism to a higher vehicle speed side as the deceleration of the vehicle is larger during the deceleration operation. Powertrain control device.   The engine brake correction means starts correcting the engine brake force at the timing when the rotational speed of the input shaft of the transmission mechanism starts to increase or the transmission ratio starts to change due to the downshift of the transmission mechanism during the deceleration operation. The power train control device according to claim 1, wherein the power train control device is a power train control device.

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