JP2015218715A - Vehicle driving force control unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle driving force control unit capable of improving the tracking performance of an actual driving force to a target driving force.SOLUTION: A driving force control unit 1 is used in a vehicle 10 that includes an engine 12 having a variable air-fuel ratio, and an automatic transmission 18. The driving force control unit 1 switches a lean combustion mode to a stoichiometric combustion mode before completion of gearshift by the automatic transmission 18 if a difference between a target engine torque and an actual engine torque is greater than a predetermined value during the gearshift.

Description

  The present invention relates to a driving force control apparatus for a vehicle.

  Conventionally, there is a driving force control device that realizes low fuel consumption. For example, in Patent Document 1, the target torque of the driving wheel is calculated from the accelerator opening and the vehicle speed, and the target value of the engine and the transmission that minimizes the fuel consumption rate while realizing the target torque with respect to the current vehicle speed. And a driving force control device that controls the engine and the transmission so as to achieve the target value is disclosed.

Japanese Patent Laid-Open No. 11-257112

  The above-described driving force control device still has room for improvement. For example, the driving force control device has high followability of the actual engine torque (actual driving force) actually generated by the engine with respect to the engine target engine torque (target driving force) calculated from the accelerator opening and the vehicle speed. It is desired.

  An object of the present invention is to provide a vehicle driving force control device capable of improving the followability of an actual driving force with respect to a target driving force.

  A vehicle driving force control device according to the present invention is a vehicle driving force control device including an engine and a transmission capable of changing an air-fuel ratio, and includes a target driving force and an actual driving force during a shift by the transmission. When the difference is larger than a predetermined value, the air-fuel ratio is changed to the rich side before the shift is completed.

  The vehicle driving force control apparatus according to the present invention has an effect of improving the followability of the actual driving force with respect to the target driving force.

FIG. 1 is a schematic configuration diagram of a vehicle according to an embodiment. FIG. 2 is a flowchart illustrating an example of the driving force control according to the embodiment. FIG. 3 is a time chart according to an example of driving force control.

  Hereinafter, a vehicle driving force control apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[Embodiment]
The embodiment will be described with reference to FIGS. 1 to 3. The present embodiment relates to a driving force control apparatus for a vehicle. FIG. 1 is a schematic configuration diagram of a vehicle according to an embodiment of the present invention, FIG. 2 is a flowchart illustrating an example of driving force control according to the embodiment, and FIG. 3 is a time chart according to an example of driving force control.

  As shown in FIG. 1, the vehicle 10 includes an engine 12, a torque converter 14, an automatic transmission 18 (corresponding to a transmission), driving wheels 26, and a driving force control device 1. The engine 12 is an example of a driving force source, and converts combustion energy of an air-fuel mixture containing air and fuel into a rotational motion and outputs it. The engine 12 can change the ratio of air to fuel, that is, the air-fuel ratio. The engine 12 is connected to the input shaft 16 of the automatic transmission 18 via the torque converter 14. An output shaft 20 of the automatic transmission 18 is connected to left and right drive wheels 26 via a differential gear 22 and left and right drive shafts 24.

  The torque converter 14 transmits torque by fluid transmission between a pump impeller connected to the engine 12 and a turbine runner connected to the input shaft 16 of the automatic transmission 18. The torque converter 14 further has a lockup clutch.

  The automatic transmission 18 includes one or a plurality of planetary gear devices disposed in a transmission case as a non-rotating member attached to the vehicle body, and a plurality of engagement devices. The automatic transmission 18 is a planetary gear type stepped automatic transmission in which a plurality of gear stages are alternatively realized by an engagement device. The automatic transmission 18 performs clutch-to-clutch shift by re-holding a plurality of engagement devices, that is, by releasing the engagement device on the release side and engaging the engagement device on the engagement side. Each of the plurality of engaging devices transmits torque between the input shaft 16 and the output shaft 20. The engagement device is a hydraulic friction engagement device, and for example, a wet multi-plate clutch can be used.

  The driving force control device 1 controls each part of the vehicle 10. The driving force control apparatus 1 of this embodiment is an electronic control unit including a computer.

  The driving force control device 1 includes an engine speed sensor that detects the engine speed, a turbine speed sensor that detects the speed of the turbine runner of the torque converter 14, and an output shaft speed sensor that detects the speed of the output shaft 20. Is connected. The driving force control device 1 calculates the vehicle speed of the vehicle 10 from the rotational speed of the output shaft 20. Connected to the driving force control device 1 is an accelerator opening sensor that detects the accelerator opening, a throttle opening sensor that detects the throttle valve opening of the engine 12, and a shift sensor that detects a shift operation for a shift lever or paddle switch. Has been.

  The driving force control device 1 outputs a command value related to throttle control, fuel injection control, ignition control, and the like of the engine 12 based on the required engine torque. Further, the driving force control device 1 calculates a target driving force for the vehicle 10. The target driving force is calculated based on, for example, the accelerator opening and the vehicle speed. The driving force control device 1 determines a torque value that can generate a target driving force based on the gear ratio of the gear stage after the shift of the automatic transmission 18, the torque ratio of the torque converter 14, etc. as a target engine torque (target driving force Equivalent). The torque ratio is calculated based on, for example, the relationship between the speed ratio (= rotation speed of turbine runner / pump (engine speed)), torque ratio, efficiency, and capacity coefficient.

  The driving force control device 1 executes shift control of the automatic transmission 18. The driving force control device 1 makes a shift determination based on a relationship (shift map or shift diagram) stored in advance with the vehicle speed and the accelerator opening as variables. When the driving force control device 1 determines that the shift of the automatic transmission 18 should be executed, the drive force control device 1 executes the shift of the automatic transmission 18 and switches from the gear stage before the shift to the gear stage after the shift. The driving force control device 1 outputs a hydraulic pressure command signal for switching the gear stage of the automatic transmission 18 to the target gear stage to the hydraulic control circuit 28 of the automatic transmission 18.

  As the shift control, for example, the torque capacity (or hydraulic pressure command of each engagement device at the time of the shift is determined based on a control map determined by the adaptation while evaluating whether the shift shock, the shift time, etc. are appropriate. There is a method of determining the value) and executing the shift of the automatic transmission 18. As the control map, a control map corresponding to any shift pattern of power-on upshift, power-off upshift, power-on downshift, and power-off downshift is used.

  The driving force control device 1 calculates the target clutch torque based on the detection result of each sensor. The driving force control device 1 is an engine torque actually generated by the engine 12 based on the relationship among the fuel injection amount, the air amount, the ignition timing, and the engine speed (hereinafter referred to as an actual engine torque). Is calculated, and the actual engine torque is calculated based on the fuel injection amount, the air amount, the ignition timing, the engine speed, and the torque conversion map.

  The driving force control device 1 stores a map or the like that can calculate the “target value of the rotational speed change amount” and the “target value of the output shaft torque” based on the detection result of each sensor. The driving force control device 1 calculates the target clutch torque and the target engine torque using the gear train motion equation based on the “target value of the rotational speed change amount” and the “target value of the output shaft torque”. The driving force control device 1 performs model-based control for controlling the engine 12, the torque converter 14, the automatic transmission 18, and the like using the target clutch torque and the target engine torque as control target values.

  The driving force control device 1 switches the combustion mode of the engine 12 between a lean combustion mode and a stoichiometric combustion mode. The lean combustion mode refers to a mode in which an air-fuel mixture having a higher air-fuel ratio than the stoichiometric air-fuel ratio is combusted, and the stoichiometric combustion mode refers to a mode in which an air-fuel mixture having a stoichiometric air-fuel ratio is combusted. Further, the driving force control device 1 stores a lean combustion region of engine operating conditions. The lean combustion region is determined by the engine speed, target engine torque, and the like. The driving force control device 1 controls the opening degree of the throttle valve, the ignition timing of the engine spark plug, and the like.

  Next, an example of the driving force control of this embodiment will be described with reference to FIGS. FIG. 3 shows the operation during power-on downshift. In FIG. 3, (a) the target gear stage of the automatic transmission 18, (b) the accelerator opening, (c) the target engine torque (shown by a dotted line) and the actual engine torque (shown by a solid line), (d) the engine The combustion mode, (e) the amount of intake air to the engine, (f) the ignition timing of the engine, (g) the engine speed, and (h) the speed of the output shaft 20 are shown.

  The control flow shown in FIG. 2 is repeatedly executed at predetermined intervals. In step S10, it is determined by the driving force control device 1 whether or not the gear is being changed (power-on downshift) and is in the inertia phase. As a result of the determination in step S10, if it is determined that the gear is being shifted (power-on downshift) and is in the inertia phase (step S10-Y), the process proceeds to step S20, and if not (step S10-N). This control flow ends. In FIG. 3, it is determined that the shift is being performed (power-on downshift) from time t1 to time t5. From time t2 to time t4, it is determined that the inertia phase is in progress. In FIG. 3A, only two gear stages are shown, and other gear stages are omitted.

  In step S20, the driving force control device 1 calculates the target clutch torque and the target engine torque from the gear train motion equation based on the “target value of the rotational speed change amount” and the “target driving force during shifting”. Specifically, the driving force control device 1 calculates the “target value of the rotational speed change amount” and the “target driving force during shifting” based on the detection result of each sensor, a map stored in advance, and the like. The target clutch torque and the target engine torque are calculated using the gear train equation of motion based on the calculated “target value of the amount of change in rotational speed” and “target driving force during shifting”. Furthermore, the actual engine torque is calculated by the driving force control device 1 based on the detection result of each sensor, a torque conversion map, and the like. When step S20 is executed, the process proceeds to step S30.

  In step S30, the driving force control device 1 determines a difference between the target engine torque (shown by a dotted line in FIG. 3C) and the actual engine torque (shown by a solid line in FIG. 3C). It is determined whether or not the value α is larger. As a result of step S30, if it is determined that the value is larger than the predetermined value α (step S30-Y), the process proceeds to step S40, and if not (step S30-N), the control flow ends. In FIG. 3, it is determined that the value is larger than the predetermined value α at time t3 between time t2 and time t4 during the inertia phase.

  In step S40, the driving force control device 1 switches (changes) the combustion mode of the engine 12 from the lean combustion mode to the stoichiometric combustion mode. Then, between time t3 and time t4, the increase amount of the engine speed (shown by a solid line in FIG. 3G) is greater than the increase amount by the lean combustion mode (shown by a dotted line in FIG. 3G). Will also increase. When step S40 is executed, the process proceeds to step S50.

  In step S50, it is determined by the driving force control device 1 whether or not the shift has been completed based on the detection result of each sensor or the like. As a result of step S50, when it is determined that the shift is completed (step S50-Y), the process proceeds to step S60, and otherwise (step S50-N), the control flow ends. In FIG. 3, it is determined that the shift has been completed at time t5.

  In step S60, the driving force control device 1 determines whether or not the operating condition of the engine is a lean combustion region based on the detection result of each sensor or the like. If it is determined that the region is the lean combustion region (step S60-Y), the process proceeds to step S70, and if not (step S60-N), the control flow ends. In FIG. 3, at the time t6, it is determined to be a lean combustion region.

  In step S70, the throttle valve is controlled by the driving force control device 1 to increase the intake amount to the amount necessary for the lean combustion mode, and the spark plug is controlled to cancel (decrease) the surplus torque due to the stoichiometric combustion. Thus, the ignition timing is retarded. When step S70 is executed, the process proceeds to step S80.

  In step S80, it is determined by the driving force control device 1 whether or not the intake air amount has reached the intake air amount necessary for lean combustion based on the detection results of the sensors and the like. If it is determined that the intake amount necessary for lean combustion has been reached (step S80-Y), the process proceeds to step S90, and if not (step S80-N), the control flow ends. In FIG. 3, it is determined that the intake amount necessary for lean combustion has been reached at time t6.

  In step S90, the driving force control device 1 switches the engine combustion mode to the lean combustion mode, and the ignition timing of the spark plug is also restored. In FIG. 3, the intake air amount is kept constant after time t6, and the rotation speed of the output shaft 20 is kept constant during this control flow. When step S90 is executed, the control flow ends.

  As described above, when the difference between the target engine torque and the actual engine torque is larger than the predetermined value α during the shift by the automatic transmission 18, the driving force control apparatus 1 of the present embodiment performs the inertia phase before the shift is completed. Meanwhile, the air-fuel ratio of the engine 12 is changed to a stoichiometric combustion mode that is richer than the lean combustion mode. When the power-on downshift is performed during the lean combustion mode, the driving force control apparatus 1 of the present embodiment switches to the stoichiometric combustion mode if the difference between the target engine torque and the actual engine torque is greater than a predetermined value α. Originally, the lean combustion mode requires a larger amount of intake air in order to output the same engine torque than the stoichiometric combustion mode. For this reason, the lean combustion mode is affected by the responsiveness of the turbocharger, etc., and the responsiveness when increasing the actual engine torque is low. A delay in engine torque occurs. On the other hand, the stoichiometric combustion mode can output a larger engine torque than the lean combustion mode when the intake air amount is the same. For this reason, when the lean combustion mode is switched to the stoichiometric combustion mode, the actual engine torque can be rapidly increased even if the intake air amount remains the same.

  For this reason, since the driving force control device 1 switches to the stoichiometric combustion mode even when the engine 12 is burning in the lean combustion mode, the followability of the actual driving force with respect to the target driving force can be improved.

  Further, the driving force control device 1 switches from the lean combustion mode to the stoichiometric combustion mode when the difference between the target engine torque and the actual engine torque is larger than the predetermined value α during the shift by the automatic transmission 18 and during the inertia phase. . For this reason, the driving force control apparatus 1 can suppress the shift shock caused by the sudden increase in the actual engine torque due to the clutch slip of the automatic transmission 18. Further, since the driving force control device 1 can suppress a shift shock caused by a sudden increase in the actual engine torque due to the clutch slip of the automatic transmission 18, the stoichiometric combustion is performed from the lean combustion mode than when the combustion mode is switched when the gear stage is fixed. Switching shock when switching to the mode can be reduced.

  Further, the driving force control device 1 switches the combustion mode of the engine 12 to the lean combustion mode when the engine operating conditions such as the target engine torque and the engine speed are in the lean combustion region after the shift is completed. For this reason, the driving force control apparatus 1 can suppress an increase in the fuel consumption amount of the vehicle. Further, when switching to the lean combustion mode, the driving force control device 1 increases the intake amount required for the lean combustion mode during the stoichiometric combustion mode, and retards the ignition timing in order to suppress the actual engine torque. Let For this reason, the driving force control apparatus 1 can suppress a change in the actual engine torque when switching from the stoichiometric combustion mode to the lean combustion mode.

  In the above-described embodiment, the driving force control device 1 determines whether or not the power-on downshift and the inertia phase are in progress in step S10. However, in the present invention, the present invention is not limited to this, and the driving force control apparatus 1 may determine whether or not the power-on upshift and the inertia phase are being performed in step S10. In step S30, the driving force control apparatus 1 may determine whether the rate of change of the target engine torque is greater than a predetermined value β. Further, in the present invention, the driving force control apparatus 1 may change the fuel to the rich side (the air-fuel ratio is higher than the stoichiometric) in the lean combustion mode without necessarily switching to the stoichiometric combustion mode in step S40.

  The contents disclosed in the above embodiment can be changed and executed as appropriate.

DESCRIPTION OF SYMBOLS 1 Driving force control apparatus 10 Vehicle 12 Engine 18 Automatic transmission (transmission)

Claims (1)

A vehicle driving force control device including an engine and a transmission capable of changing an air-fuel ratio,
When the difference between the target driving force and the actual driving force is larger than a predetermined value during shifting by the transmission, the air-fuel ratio is changed to the rich side before shifting is completed. apparatus.

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