JP2011214453A - Vehicle control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control system capable of adjusting deceleration in accordance with the demand of a driver.SOLUTION: The vehicle control system includes an engine, a deceleration adjusting means capable of varying the deceleration of a vehicle during fuel cut control, and a control device, and the control device controls the engine based on the target torque of the engine determined based on correspondence relationship between an accelerator opening and a target value of acceleration during operation of the engine. The control device allows execution of fuel cut control when the fuel cut execution condition including the condition that the accelerator opening is equal to or lower than a prescribed opening (S11-Y) is satisfied, and during execution of fuel cut control (S12-Y), controls the deceleration adjusting means in accordance with the accelerator opening in a region equal to or lower than the prescribed opening, and adjusts the deceleration acting on the vehicle (S14, S17). The prescribed opening is varied in accordance with a vehicle speed, and the prescribed opening in at least a part of a region of the vehicle speed is larger than the opening corresponding to the full close.

Description

  The present invention relates to a vehicle control system.

  Conventionally, a target acceleration, which is an acceleration requested by the driver, is determined based on the vehicle speed of the vehicle and the accelerator operation amount (accelerator opening, pedal effort, etc.) when the driver operates the accelerator pedal. 2. Description of the Related Art An acceleration generator that generates acceleration in a vehicle based on acceleration, for example, so-called torque demand control that controls engine output torque is known. For example, Patent Document 1 discloses an engine that prevents engine torque demand control from continuing to occur even when idling and prevents target torque from being reduced when the rotational speed is reduced due to disturbance during idling. The technology of the idle speed control device is disclosed.

JP 10-325349 A

  It is desired that the acceleration (deceleration) can be controlled according to the driver's request not only when the vehicle is accelerating but also when the vehicle is decelerating. For example, it is preferable that the deceleration of the vehicle can be controlled according to a driver's request during execution of fuel cut control for stopping the supply of fuel to the engine.

  An object of the present invention is to provide a vehicle control system capable of controlling deceleration according to a driver's request during deceleration.

  A vehicle control system according to the present invention includes an engine mounted on a vehicle, and deceleration adjusting means capable of changing a deceleration acting on the vehicle during execution of fuel cut control for stopping supply of fuel to the engine. And a control device for controlling the engine and the deceleration adjusting means. The control device adjusts the accelerator opening and the acceleration during the operation of the engine in which fuel is supplied to the engine and the engine outputs torque. When the engine is controlled based on the target torque of the engine determined based on a correspondence relationship with a target value related to speed, and a fuel cut execution condition including a condition that the accelerator opening is equal to or less than a predetermined opening is satisfied The execution of the fuel cut control is permitted, and during the execution of the fuel cut control, the region is below the predetermined opening. And adjusting the deceleration acting on the vehicle by controlling the deceleration adjusting means according to the accelerator opening, and the predetermined opening changes according to the vehicle speed of the vehicle, and the vehicle speed The predetermined opening degree in at least a partial region of the accelerator is larger than an opening degree corresponding to full closing in the accelerator opening degree.

  In the vehicle control system, it is preferable that the predetermined opening on the high vehicle speed side of the vehicle speed is larger than the predetermined opening on the low vehicle speed side of the vehicle speed.

  In the vehicle control system, in the correspondence relationship, it is preferable that the target value when the accelerator opening is the predetermined opening corresponds to a minimum torque that the engine can output during operation of the engine. .

  The vehicle control system includes an alternator that is driven by torque transmitted from the engine to generate electric power and adjusts the electric power generation amount as the deceleration adjusting means, and the control device is executing the fuel cut control. In addition, it is preferable to adjust the deceleration acting on the vehicle by adjusting the power generation amount of the alternator.

  In the vehicle control system according to the present invention, the control device controls the engine based on the target torque of the engine determined based on the correspondence relationship between the accelerator opening and the target value related to acceleration / deceleration during engine operation. Further, the control device permits execution of the fuel cut control when a fuel cut execution condition including a condition that the accelerator opening is equal to or less than the predetermined opening is satisfied, and the predetermined opening degree during execution of the fuel cut control. In the following area, the deceleration adjusting means is controlled according to the accelerator opening to adjust the deceleration acting on the vehicle. The predetermined opening changes according to the vehicle speed of the vehicle, and the predetermined opening in at least a part of the vehicle speed is larger than the opening corresponding to the fully closed accelerator opening. Thus, according to the vehicle control system of the present invention, it is possible to control the deceleration according to the driver's request during deceleration.

FIG. 1 is a flowchart showing the operation of the vehicle control system according to the embodiment. FIG. 2 is another flowchart showing the operation of the vehicle control system according to the embodiment. FIG. 3 is a schematic configuration diagram of a vehicle according to the embodiment. FIG. 4 is a diagram illustrating a relationship among the vehicle speed, the accelerator opening, and the target driving force. FIG. 5 is a diagram showing the relationship between the accelerator opening and the target driving force.

  Hereinafter, an embodiment of a vehicle control system according to 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 5. The present embodiment relates to a vehicle control system including a deceleration adjusting means that can change a deceleration acting on a vehicle during execution of fuel cut control. FIG. 1 is a flowchart showing the operation of the embodiment of the vehicle control system according to the present invention, and FIG. 2 is another flowchart showing the operation of the vehicle control system of this embodiment.

  FIG. 3 is a schematic configuration diagram of a vehicle to which the vehicle control system according to the present embodiment is applied. In FIG. 3, the code | symbol 1 shows a vehicle. The power train of the vehicle 1 includes an engine 10, a torque converter 20, and a continuously variable transmission 30. A continuously variable transmission (CVT) 30 as an automatic transmission is connected to the engine 10 as an internal combustion engine via a torque converter 20. The engine output torque (driving force) of the engine 10 is input to the continuously variable transmission 30 via the torque converter 20 and transmitted to the drive wheels 90 via the differential gear 18 and the drive shaft 19.

  The continuously variable transmission 30 is a known belt-type continuously variable transmission, and is provided on the engine 10 side. The primary pulley 31 connected to the output shaft 70 of the torque converter 20 and the output shaft connected to the differential gear 18. A secondary pulley 32 connected to the belt 80 and a belt 33 stretched between them are provided. The hydraulic control device 40 changes the gear ratio of the continuously variable transmission 30 in accordance with a gear ratio change command input from the ECU 50. The hydraulic control device 40 can change the pulley ratio steplessly by adjusting the transmission pressure to the primary pulley side actuator and the line pressure to the secondary pulley side actuator to change the pulley ratio.

  The continuously variable transmission 30 includes a primary pulley rotation sensor 34 that detects the rotation speed (primary rotation speed) of the primary pulley 31 and a secondary pulley rotation sensor 35 that detects the rotation speed (secondary rotation speed) of the secondary pulley 32. And the detected primary rotational speed and secondary rotational speed are output to the ECU 50.

  The torque converter 20 connects the continuously variable transmission 30 and the engine 10. The torque converter 20 has a known lock-up mechanism, and is a torque converter with a lock-up clutch that is a power interrupting means that can be coupled and released. The lockup clutch performs mechanical coupling (lockup state) or release (converter state) between the engine 10 and the continuously variable transmission 30. The input shaft 60 of the torque converter 20 is provided with a rotation sensor 21 that detects the rotational speed of the input shaft 60. The input shaft rotation speed detected by the rotation sensor 21 is output to the ECU 50.

  The vehicle 1 is provided with an ECU (electronic control unit) 50 that controls the engine 10, the continuously variable transmission 30, and the like. The ECU 50 includes the engine 10, the torque converter 20, and the continuously variable transmission 30 (hydraulic control device). 40) Comprehensive control is performed. The ECU 50 includes an input / output device, a storage device (ROM, RAM, etc.) that stores a control map and a control program, an arithmetic device, an A / D converter, a D / A converter, a communication driver circuit, and the like. . The ECU 50 of this embodiment functions as a control device that controls the engine 10 and the alternator 25 as a deceleration adjusting means. The vehicle control system of the present embodiment includes an engine 10, an alternator 25, and an ECU 50.

  Further, the vehicle 1 is provided with an accelerator position sensor 11 that detects the amount of operation of the accelerator pedal (accelerator opening), and the detected accelerator opening is output to the ECU 50. An electronic throttle valve 13 is provided in the intake pipe 12 of the engine 10, and the electronic throttle valve 13 can be opened and closed by a throttle actuator 14. The ECU 50 drives the electronic throttle valve 13 by the throttle actuator 14 and can control the throttle opening to an arbitrary opening regardless of the accelerator opening. A throttle position sensor 15 for detecting the fully closed state of the electronic throttle valve 13 and the throttle opening is provided, and the detected throttle opening is output to the ECU 50.

  The engine 10 is provided with an engine speed sensor 17 that detects an engine speed (engine speed), and the detected engine speed is output to the ECU 50. Further, the vehicle 1 is provided with a vehicle speed sensor 51 that detects the traveling speed of the vehicle 1 and a shift position sensor 52 that detects the position of a shift lever operated by the driver, and the detected vehicle speed. The shift position is output to the ECU 50.

  The engine 10 includes an alternator 25. The alternator 25 is an auxiliary machine that rotates in conjunction with the rotation of the engine 10. The alternator 25 is connected to the engine 10 via a belt or the like so that power can be transmitted. Thereby, the alternator 25 rotates in conjunction with the rotation of the engine 10 and is driven by the torque transmitted from the engine 10 to convert mechanical power into electrical energy and generate electric power. The alternator 25 can adjust the amount of power generation, and can apply an alternator load torque, which is a torque corresponding to the power generation load (drive load), to the drive wheels 90 via the engine 10. The alternator 25 is connected to the ECU 50, and the power generation amount, in other words, the power generation load is controlled by the ECU 50, and the alternator load torque corresponding to the power generation load is applied to the drive wheels 90. In the present embodiment, the alternator 25 functions as a deceleration adjusting means that changes the deceleration acting on the vehicle 1 during execution of the fuel cut control.

  The ECU 50 determines the fuel injection amount, the injection timing, the ignition timing, and the like based on the operating state of the engine 10 such as the engine speed, the intake air amount, and the throttle opening, and controls the injector, the ignition plug, and the like. Further, the ECU 50 has a shift map, determines the gear ratio of the continuously variable transmission 30 based on the throttle opening, the vehicle speed, and the like, and the hydraulic control device 40 so as to establish the determined gear ratio. To control.

  Further, the ECU 50 determines the target driving force based on the driver's request based on the accelerator opening as the input value and the vehicle speed (corresponding to the output rotation speed of the continuously variable transmission 30), and the determined target driving force. Based on the above, so-called driving force demand control is performed for controlling the output torque of the engine 10 or the like. The ECU 50 stores a correspondence relationship between a predetermined accelerator opening and a target value related to acceleration / deceleration, and realizes a correspondence relationship between the accelerator opening and a target value related to acceleration / deceleration according to the accelerator operation by the driver. So that the output torque of the power train is controlled.

  The ECU 50 determines the operating conditions (target output torque, target engine speed) of the engine 10 and the continuously variable transmission based on a target driving force determined from a correspondence relationship between a predetermined accelerator opening, vehicle speed, and target driving force. A target value for the input rotational speed of 30 is determined. The ECU 50 performs intake control, fuel injection control, ignition control, and the like of the engine 10 so as to realize the determined operating conditions of the engine 10. That is, the ECU 50 determines the target torque of the engine 10 determined based on the correspondence between the accelerator opening and the target value related to acceleration / deceleration during operation of the engine 10 in which fuel is supplied to the engine 10 and the engine 10 outputs torque. The engine 10 is controlled based on the above. Further, the ECU 50 determines a gear ratio from the target value of the input rotation speed and the output rotation speed (vehicle speed) of the continuously variable transmission 30, and controls the continuously variable transmission 30 so as to realize the gear ratio. The target value related to acceleration / deceleration may be a target value of acceleration / deceleration itself, or may be a target value of driving force or torque.

  In the present embodiment, when a predetermined fuel cut execution condition is satisfied, execution of fuel cut control is permitted by the ECU 50, and fuel cut control for stopping the supply of fuel to the engine 10 is executed. The fuel cut execution condition includes a condition in which an idle ON determination is made. In addition, the fuel cut execution condition may include a condition in which the engine speed Ne is equal to or higher than a predetermined speed, a condition in which the engine water temperature is equal to or higher than a predetermined water temperature, and the like.

  Conventionally, in the driving force demand control, the idling determination is sometimes made based on a comparison result between an engine minimum torque that can be realized at the time of fuel injection and an engine required torque based on a target driving force. For example, when the engine required torque is equal to or less than the engine minimum torque, it is determined that the engine is idle ON. However, since the engine minimum torque is affected by the load on the auxiliary machine, the engine friction, and the reduction ratio, the idle determination may become unstable or the idle determination may not match the driver's experience.

  In the vehicle control system of the present embodiment, it is determined that the idle is ON when the accelerator opening is equal to or less than a predetermined opening. The predetermined opening is determined according to the vehicle speed, and is not affected by auxiliary machine load, engine friction, reduction ratio, or the like. Thereby, it is possible to reliably determine whether the idle is on or idle off. Further, as described below, at the idle determination reference value (predetermined opening), the engine required torque corresponding to the target driving force is the minimum torque that the engine 10 can output during operation of the engine 10 (at the time of fuel injection). (Hereinafter, simply described as “engine minimum realizable torque”), the correspondence relationship between the accelerator opening and the target driving force is determined. Thereby, the conventional fluctuation factor can be avoided and the continuity of the driving force from the acceleration to the deceleration fuel cut state can be ensured. Further, the idle determination reference value is set such that the accelerator opening is 0% on the low vehicle speed side, and the accelerator opening is 5% on the medium vehicle speed or higher. At medium vehicle speeds or higher, negative torque control is performed to moderately control deceleration in the accelerator opening range below the idle judgment reference value. At low vehicle speeds, target torque is set to improve acceleration / deceleration response by eliminating negative torque control. It is said that.

  FIG. 4 is a diagram illustrating a relationship among the vehicle speed, the accelerator opening, and the target driving force in the vehicle control system of the present embodiment. In FIG. 4, the horizontal axis represents the vehicle speed SPD, and the vertical axis represents the target driving force F. In the present embodiment, the predetermined opening degree Acc_idl, which is an idle determination reference value, changes according to the vehicle speed, as shown in FIG. The predetermined opening Acc_idl is close to the accelerator opening 0% (Acc 0%) in the low vehicle speed region, and close to the accelerator opening 5% (Acc 5%) at the medium vehicle speed or higher. Further, the predetermined opening degree Acc_idl in at least a part of the vehicle speed SPD is larger than the opening degree (0%) corresponding to the fully closed state of the accelerator opening degree. In the present embodiment, the predetermined opening degree Acc_idl is set to be larger than 0% at least in the region of the medium vehicle speed or higher.

  Note that the low vehicle speed can be a vehicle speed region in which fuel cut control cannot be executed, and the medium vehicle speed or more can be a vehicle speed region in which fuel cut control can be executed. For example, in a power train in which the reduction ratio of the continuously variable transmission 30 is uniquely determined according to the combination of the accelerator opening Acc and the vehicle speed SPD, the low vehicle speed region is determined based on the lower limit vehicle speed at which fuel cut control can be performed. The middle vehicle speed region may be separated.

  In a low vehicle speed range, for example, a range of 15 km / h or less, there is no opportunity for fuel cut. Therefore, the predetermined opening degree Acc_idl is set to 0%, and the responsiveness of the engine torque to the accelerator depression is emphasized. At other medium vehicle speeds or higher, the predetermined opening Acc_idl is set to a value larger than the low vehicle speed region, for example, 5%, so that negative torque control can be performed when idling and fuel cut is performed. As shown in FIG. 4, the predetermined opening degree Acc_idl is preferably gradually increased as the vehicle speed increases, but is not limited thereto. The predetermined opening degree Acc_idl may be increased stepwise as the vehicle speed SPD increases. In addition, the predetermined opening degree Acc_idl is made larger than the other vehicle speed regions at the medium vehicle speed or higher, but the correspondence relationship between the vehicle speed and the magnitude of the predetermined opening degree Acc_idl is not limited to this.

  When the accelerator opening Acc is less than the predetermined opening Acc_idl, it is determined that the engine is idle ON, and the fuel cut control is executed when all the conditions including the idle ON are satisfied and the fuel cut execution condition is satisfied.

  During execution of the fuel cut control, in the accelerator opening region R1 equal to or less than the predetermined opening Acc_idl, negative torque control for controlling the deceleration acting on the vehicle 1 is executed according to the accelerator opening. FIG. 5 is a diagram showing the relationship between the accelerator opening Acc and the target driving force F in the driving force control of the present embodiment. In FIG. 5, reference numeral 101 indicates a target driving force-accelerator opening characteristic (hereinafter referred to as “negative torque control characteristic”) in negative torque control, and reference numeral 102 indicates that fuel is supplied to the engine 10. This is a target driving force-accelerator opening characteristic (hereinafter referred to as “engine operating characteristic”), and shows a correspondence relationship between the accelerator opening and a target value related to acceleration / deceleration. Reference numeral 103 is a diagram illustrating an example of a target driving force-accelerator opening characteristic when the idle determination reference value is not changed according to the accelerator opening Acc. When the idle determination reference value is not changed according to the accelerator opening Acc (103), the idle determination reference value is, for example, the accelerator opening Acc 0% (fully closed).

  In the present embodiment, the target driving force F changes according to the magnitude of the accelerator opening Acc in the region R1 where the accelerator opening Acc is 0% to the predetermined opening Acc_idl. The target driving force F increases as the accelerator opening Acc increases. This region R1 is a region where fuel cut control can be executed, and the target driving force F is a negative value. That is, in this region R1, negative torque control for controlling (adjusting) the deceleration generated in the vehicle 1 according to the accelerator opening is executed. The deceleration is adjusted by adjusting the alternator load torque generated by the alternator 25.

  By performing negative torque control in this way, the driver can control the deceleration of the vehicle 1 by accelerator control. When the accelerator opening Acc is close to 0%, a large deceleration can be generated. On the other hand, when a very large deceleration is not required, the vehicle 1 can be coasted by slightly depressing the accelerator. Thereby, the controllability of the deceleration is improved, and the drivability can be improved. In particular, in the vehicle speed range above the medium vehicle speed, the controllability of the deceleration is improved because the width of the region R1 is large. Even if the fuel cut control is not being executed, it is possible to execute the negative torque control by adjusting the alternator load torque.

  Further, when the accelerator opening Acc is equal to or greater than the predetermined opening Acc_idl during the fuel cut control, the engine is idled off and the fuel cut control is terminated. At this time, the driving force difference ΔF between the negative torque control characteristic 101 and the engine operating characteristic 102 at the predetermined opening Acc_idl is compared with the driving force difference ΔF0 generated when the idling determination is performed at the accelerator opening Acc 0%. And small. That is, according to the vehicle control system of the present embodiment, torque fluctuation is suppressed when shifting to the fuel cut control or when the engine 10 is restarted after returning from the fuel cut control.

  In particular, in this embodiment, the engine operating characteristic 102 is set so that the engine minimum realizable torque Temin_isc is determined at the predetermined opening degree Acc_idl. As shown in FIG. 5, the engine operating characteristic 102 is set in advance so that the target driving force F at the predetermined opening Acc_idl becomes the driving force F (Temin_isc) corresponding to the engine minimum feasible torque Temin_isc. The engine minimum feasible torque Temin_isc varies depending on the vehicle speed SPD. At each vehicle speed SPD, the engine operating characteristic 102 is set so that the target driving force F at the predetermined opening Acc_idl becomes a driving force corresponding to the engine minimum feasible torque Temin_isc. Is set. That is, as shown in FIG. 4, the engine minimum feasible torque Temin_isc line is defined as a line that coincides with the predetermined opening degree Acc_idl line.

  Accordingly, the target driving force F immediately before shifting to the fuel cut control or immediately after returning from the fuel cut control becomes a value corresponding to the engine minimum feasible torque Temin_isc, and therefore the driving force from the acceleration to the deceleration fuel cut state. Is ensured. The reduction ratio of the continuously variable transmission 30 is uniquely determined by the accelerator opening degree Acc and the vehicle speed SPD, but the engine operating characteristic 102 is set in consideration of the coast reduction ratio (fixed value). . In the engine operating characteristic 102, the value at the predetermined opening Acc_idl is preferably an acceleration corresponding to the engine minimum realizable torque Temin_isc, but is not limited to this, and other values may be adopted. .

  In the present embodiment, the target value determined based on the vehicle speed SPD and the accelerator opening Acc is the target driving force F. However, the target value is not limited to this, and the determined target value may be the target torque or the target It may be acceleration. In any case, it is preferable that the characteristic is set so that the torque required of the engine 10 based on the target value becomes the engine minimum realizable torque Temin_isc at the predetermined opening degree Acc_idl.

  Since the engine operating characteristic 102 is set in this manner, the target acceleration G (target driving force F) is not affected by auxiliary machine load (auxiliary machine loss), engine friction, reduction ratio, and the like. In the final determination of the engine output torque, the shaft torque request value of the engine 10 based on the target acceleration G is calculated, and torque such as auxiliary machine loss and engine friction is corrected on the engine 10 side. Good.

  The change of the negative torque control characteristic 101 and the engine operating characteristic 102 depending on the vehicle speed will be described. In the low vehicle speed region, the predetermined opening Acc_idl approaches the accelerator opening Acc 0%, and thus the negative torque control characteristic 101 and the engine operating characteristic The characteristics 102 are close to the characteristics in which the idle determination reference value indicated by reference numeral 103 is the accelerator opening Acc 0%. In other words, in the low vehicle speed region, as shown in FIG. 4, the width of the accelerator opening Acc area in which negative torque control is performed (width in the direction of increase / decrease of the accelerator opening) W2 is the width W1 in the region above the medium vehicle speed. Narrower than that. As a result, in the low vehicle speed region, the acceleration response is improved by starting the operation of the engine 10 with a slight depression of the accelerator.

  The operation of the present embodiment will be described with reference to the flowcharts of FIGS.

  FIG. 1 shows a flow of control for performing the idle determination process, and FIG. 2 shows a flow of control for performing the torque distribution process. The determination process of FIG. 1 and the determination process of FIG. 2 are each executed at predetermined intervals, and can be executed alternately, for example.

  First, referring to FIG. 1, in step S1, it is determined by the ECU 50 whether or not the accelerator opening Acc is less than a predetermined opening Acc_idl (spd). The predetermined opening degree Acc_idl (spd) is a function of the vehicle speed SPD as described above. The ECU 50 determines a predetermined opening Acc_idl (spd) based on the vehicle speed SPD detected by the vehicle speed sensor 51. The ECU 50 stores a relationship between the vehicle speed SPD and the predetermined opening Acc_idl (spd) in advance as a map, for example, and calculates the predetermined opening Acc_idl (spd) with reference to the map. The ECU 50 compares the current accelerator opening Acc detected by the accelerator position sensor 11 with the predetermined opening Acc_idl and performs the determination in step S1. As a result of the determination, if it is determined that the accelerator opening Acc is less than the predetermined opening Acc_idl (spd) (step S1-Y), the process proceeds to step S2, and if not (step S1-N), the process proceeds to step S2. Proceed to S3.

  In step S2, the ECU 50 sets the idle flag Xidl_ptm to ON. When the idle flag Xidl_ptm is ON, it indicates an idle ON state, and when the idle flag Xidl_ptm is OFF, it indicates an idle OFF state. When step S2 is executed, this control flow ends.

  On the other hand, in step S3, the ECU 50 sets the idle flag Xidl_ptm to OFF. When step S3 is executed, the control flow ends.

  Next, referring to FIG. 2, in step S11, the ECU 50 determines whether or not the idle flag Xidl_ptm is ON. As a result of the determination, if it is determined that the idle flag Xidl_ptm is ON (step S11-Y), the process proceeds to step S12. If not (step S11-N), the process proceeds to step S15.

  In step S12, the ECU 50 determines whether or not the fuel cut flag Xfcut is ON. If the fuel cut control execution condition regarding the engine speed Ne or the like is satisfied, the fuel cut control is executed and the fuel cut in progress flag Xfcut is turned ON. The ECU 50 determines whether or not the fuel cut flag Xfcut is currently ON. As a result of the determination, if it is determined that the fuel cut flag Xfcut is ON (step S12-Y), the process proceeds to step S13. If not (step S12-N), the process proceeds to step S16.

  In step S13, the ECU 50 determines whether or not a lockup flag (L / U flag) Xloop is ON. When the lock-up flag Xloop is ON, it indicates that the torque converter 20 is in a lock-up state in which the lock-up clutch is engaged. The ECU 50 may perform the determination in step S13 based on the detection results of the respective rotational speeds of the input shaft 60 and the output shaft 70 of the torque converter 20. As a result of the determination in step S13, if it is determined that the lockup flag Xloop is ON (step S13-Y), the process proceeds to step S14. If not (step S13-N), the process proceeds to step S16.

  In step S14, the ECU 50 determines a control amount for negative torque control during deceleration FC. The ECU 50 determines a control amount for negative torque control (negative torque control during deceleration FC) in a state in which fuel cut (FC) is executed and deceleration is occurring in the vehicle 1.

The ECU 50 first calculates the target acceleration G. The target acceleration G is determined according to the accelerator opening Acc and the vehicle speed SPD, similarly to the target driving force F shown in FIG. For example, the ECU 50 determines the target acceleration G based on the target acceleration G-accelerator opening degree Acc characteristic similar to the negative torque control characteristic 101 shown in FIG. The target driving force F can be calculated as the product of the target acceleration G and the vehicle mass M. The ECU 50 calculates the following equation (1) based on the target acceleration G, the vehicle mass M, the vehicle running resistance R, the tire radius Rtire, the differential ratio diff of the differential gear 18 and the current gear ratio gamma of the continuously variable transmission 30. The total engine required torque tereq_sys is determined.
tereq_sys = (M × G + R) × Rtire / diff / gamma (1)
The total engine required torque tereq_sys is a torque required for the entire engine 10 including not only a torque (negative torque) generated by the engine 10 but also an alternator required torque (alternate load torque) Talt required for the alternator 25. This is a required value of torque to be generated on the input shaft 60 of the torque converter 20.

The engine required torque required for the engine 10 (negative torque generated by the engine 10) Temin_fc is determined according to the engine speed Ne. The ECU 50 determines the alternator required torque Talt by the following equation (2) based on the total engine required torque tereq_sys and the engine required torque Temin_fc.
Talt = tereq_sys-Temin_fc (2)
When step S14 is executed, the process proceeds to step S17.

  When a negative determination is made in step S11 and the process proceeds to step S15, the control target for acceleration is determined by the ECU 50 in step S15. The ECU 50 determines the target acceleration G based on the current accelerator opening Acc and the vehicle speed SPD. For example, the ECU 50 determines the target acceleration G based on the target acceleration G-accelerator opening degree Acc characteristic similar to the engine operating characteristic 102 shown in FIG. Based on the determined target acceleration G, the ECU 50 determines the total engine required torque tereq_sys by the above equation (1). The alternator required torque Talt during acceleration is a standard torque. Here, the standard torque is, for example, torque generated according to the power generation load determined based on the required power generation amount, and is determined based on the current power consumption state in the vehicle 1. In other words, the standard torque is a load torque generated by satisfying the power generation request. The ECU 50 can determine the alternator request torque Talt as the standard torque based on the power demand of each auxiliary machine such as an air conditioner.

The ECU 50 determines an engine required output torque tereq that is an output torque required for the engine 10 by the following equation (3) based on the total engine required torque tereq_sys and the alternator required torque Talt determined as the standard torque.
tereq = tereq_sys-Talt (3)
When step S15 is executed, the process proceeds to step S17.

  When a negative determination is made in step S12 or step S13 and the process proceeds to step S16, in step S16, the ECU 50 determines a control amount during deceleration at which fuel cut control is not performed. The ECU 50 determines the engine minimum realizable torque Temin_isc as the output torque required for the engine 10. The minimum engine feasible torque Temin_isc varies depending on the engine speed Ne. The ECU 50 determines the engine minimum feasible torque Temin_isc based on the engine speed Ne detected by the engine speed sensor 17. Further, the ECU 50 sets a standard torque as the alternator request torque Talt. When step S16 is executed, the process proceeds to step S17.

  In step S <b> 17, the ECU 50 outputs the determined control amounts for the engine 10 and the alternator 25. In the case of negative torque control at the time of deceleration FC, the ECU 50 uses the engine required torque Temin_fc determined in step S14 as the required torque Te for the engine 10 and the alternator required torque determined in step S14 as the alternator required torque Talt for the alternator 25. Each Talt is output. The ECU 50 sets the power generation load of the alternator 25 based on the alternator request torque Talt for the alternator 25. Thereby, the alternator 25 generates an alternator load torque corresponding to the alternator request torque, and a negative torque control at the time of fuel cut is realized.

  Further, when the engine is idle-decelerated and the fuel cut is not being performed, the minimum engine feasible torque Temin_isc determined in step S16 as the required torque Te for the engine 10 is set as the required alternator torque Talt for the alternator 25 in step S16. The determined alternator request torque Talt is output. The ECU 50 controls the throttle opening, fuel injection amount, ignition timing and the like of the engine 10 so as to realize the engine minimum realizable torque Temin_isc, and sets the power generation load of the alternator 25 based on the alternator required torque Talt.

  Further, at the time of acceleration (when idling is OFF), the engine request output torque tereq determined in step S15 as the request torque Te for the engine 10 is the alternator request determined in step S15 as the alternator request torque Talt for the alternator 25. Torque Talt is output. The ECU 50 controls the throttle opening, fuel injection amount, ignition timing, and the like of the engine 10 so as to realize the engine required output torque tereq, and sets the power generation load of the alternator 25 based on the alternator required torque Talt.

  As described above, according to the vehicle control system of the present embodiment, the idle determination is reliably performed, and it can be freely performed without being affected by the auxiliary machine load, the engine friction, the reduction ratio of the continuously variable transmission 30, and the like. A negative torque control region can be determined. Further, the continuity of the driving force from the acceleration to the deceleration fuel cut state is ensured, and the torque fluctuation at the start of the fuel cut control or the return from the fuel cut control is suppressed. In addition, it emphasizes negative torque control that enables moderate negative torque control at medium vehicle speeds and higher, and does not have negative torque control at low vehicle speeds (acceleration is accelerated quickly when the accelerator is depressed). The important characteristics are realized.

  In the present embodiment, the automatic transmission is a continuously variable type, but is not limited to this. In the present embodiment, torque control is performed by changing the alternator load torque in the negative torque control. However, the present invention is not limited to this, and the opening control of the electronic throttle valve 13 and the speed change of the continuously variable transmission 30 are not limited thereto. The torque transmitted to the drive wheel 90 may be controlled by control or the like. Further, in the present embodiment, the predetermined opening degree Acc_idl is a function of the vehicle speed, but is not limited to this, and the predetermined opening degree Acc_idl is not limited to the rotation speed of the output shaft 80 of the continuously variable transmission 30 or the rotation speed of the output shaft 80. It may be a function of a value that varies correspondingly.

  Also, a predetermined opening Acc_idl (idle ON determination opening) for determining idle ON in the idle OFF state, and a predetermined opening Acc_idl (idle OFF determination opening) for determining idle OFF in the idle ON state. And may be different values. For example, the idle ON determination opening may be smaller than the idle OFF determination opening (for example, fully closed), or the idle ON determination opening may be larger than the idle OFF determination opening. .

  Further, the predetermined opening degree Acc_idl may be variable based on the driving history of the driver, the estimated driving direction, the setting contents of the driving mode, and the like. For example, it is estimated that the driver has a high frequency of controlling the negative torque in the negative torque control region, is estimated to be a driver who is directed to fuel-efficient driving that gives priority to suppression of fuel consumption, or an eco mode that instructs low fuel consumption driving. The predetermined opening degree Acc_idl may be set to a larger opening degree when it is selected or when it is not. On the other hand, the frequency with which the driver controls the negative torque in the negative torque control region is low, or the driver is presumed to be a driver who is aiming for sharp sports driving, or the sports driving mode instructing sports driving is selected. In some cases, the predetermined opening Acc_idl may be set to a smaller opening than in the case where it is not.

(Modification of the embodiment)
A modification of the embodiment will be described. The present modification is different from the above embodiment in that the target driving force-accelerator opening characteristic is different between before the fuel cut transition and after the fuel cut transition with respect to the same accelerator opening Acc.

  Specifically, even when the engine is idle ON, until the fuel cut execution conditions are all satisfied and the fuel cut control is started, a characteristic different from the negative torque control characteristic 101, for example, the reference numeral 103 in FIG. The target driving force F is determined based on the target driving force-accelerator opening characteristic when the idle determination reference value is not changed according to the accelerator opening Acc (see arrow Y1). When the fuel cut execution condition is satisfied, fuel cut control is started, and the process proceeds to determination of the target driving force F based on the negative torque control characteristic 101 (see arrow Y2). In FIG. 4, the fuel cut control is started when the accelerator opening Acc is fully closed, and the target point moves on the negative torque control characteristic 101. Even in the negative torque control region (region R1), whether or not to cut the fuel is determined by the convenience of the engine 10, so negative torque control is always performed regardless of whether or not fuel cut control is being executed. If torque control is performed along the characteristic 101, the driver may feel uncomfortable. In this modification, the negative torque control based on the negative torque control characteristic 101 is not performed until the fuel cut control is actually started, so that the driver is prevented from feeling uncomfortable.

  As described above, the vehicle control system according to the present invention is useful for driving force demand control, and is particularly suitable for performing torque control including deceleration control according to demand.

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Engine 11 Accelerator position sensor 20 Torque converter 25 Alternator 30 Continuously variable transmission 40 Hydraulic control device 50 ECU
51 Vehicle speed sensor 90 Drive wheel 101 Negative torque control characteristic 102 Engine operating characteristic Acc_idl Predetermined opening Temin_isc Minimum engine realizable torque

Claims (4)

An engine mounted on the vehicle,
Deceleration adjusting means capable of changing the deceleration acting on the vehicle during execution of fuel cut control for stopping the supply of fuel to the engine;
A control device for controlling the engine and the deceleration adjusting means,
The control device is configured to determine a target torque of the engine determined based on a correspondence relationship between an accelerator opening and a target value related to acceleration / deceleration during operation of the engine in which fuel is supplied to the engine and the engine outputs torque. The fuel cut control is permitted to be executed when a fuel cut execution condition including a condition that the accelerator opening is equal to or less than a predetermined opening is satisfied, and the fuel cut control is being executed. In addition, in the region below the predetermined opening, the deceleration adjusting means is controlled according to the accelerator opening to adjust the deceleration acting on the vehicle,
The predetermined opening changes according to the vehicle speed of the vehicle, and the predetermined opening in at least a part of the vehicle speed is larger than an opening corresponding to full closure in the accelerator opening. A vehicle control system. The vehicle control system according to claim 1, wherein the predetermined opening on the high vehicle speed side of the vehicle speed is an opening larger than the predetermined opening on the low vehicle speed side of the vehicle speed. 3. The vehicle according to claim 1, wherein, in the correspondence relationship, the target value when the accelerator opening is the predetermined opening corresponds to a minimum torque that the engine can output during operation of the engine. Control system. As the deceleration adjusting means, an alternator that is driven by torque transmitted from the engine to generate electric power and that can adjust the electric power generation amount is provided.
The vehicle control system according to any one of claims 1 to 3, wherein the control device adjusts a deceleration acting on the vehicle by adjusting a power generation amount of the alternator during execution of the fuel cut control. .

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