JP2008239130A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control device reducing a burden on a driver related to accelerator operation during constant speed driving. <P>SOLUTION: A vehicle control system has: a throttle control device 16 adjusting output of an engine 11; a continuously variable transmission 26 transmitting the output to a driving wheel side; and an ECU 50 controlling each part of the system. The ECU 50 is provided with a dead zone of acceleration F/B control in a neighborhood area of an accelerator operation amount on the basis of the accelerator operation amount when the vehicle travels at a constant speed. When the ECU 50 decides that the accelerator operation amount is out of the dead zone, the ECU 50 calculates a target acceleration based on the accelerator operation amount in each time, and executes the acceleration F/B control so that an actual acceleration of the vehicle reaches the target acceleration. When deciding that the accelerator operation amount is within the dead zone, the ECU 50 executes vehicle speed F/B control so that an actual vehicle speed reaches a target value instead of the acceleration F/B control. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle control device that performs acceleration feedback control so that the actual acceleration of a vehicle matches a target acceleration.

Conventionally, a vehicle including an electronic throttle device that adjusts an opening degree of a throttle valve of an on-vehicle internal combustion engine, and a transmission that adjusts a transmission ratio of a transmission mechanism that transmits an output of the internal combustion engine to a drive wheel side. A control device for controlling the acceleration of the motor is known (for example, see Patent Document 1). In other words, a target value of vehicle acceleration (hereinafter referred to as “target acceleration”) is set based on the amount of accelerator operation performed by the driver, and an electronic throttle device and a transmission are used to match the actual acceleration of the vehicle with the target acceleration. Acceleration feedback control is performed by controlling. According to such acceleration feedback control of the vehicle, it is possible to improve the acceleration response to the accelerator operation.
JP 2006-274823 A

  However, if the acceleration response to the accelerator operation becomes high, the following problems may occur. That is, when the vehicle is traveling at a constant speed (for example, when traveling at a constant speed on a highway), if an inadvertent accelerator operation is performed such as unintentionally depressing the accelerator pedal during the travel. Even if the operation amount is small, the vehicle is accelerated or decelerated, and as a result, the vehicle speed is shifted against the driver's intention. In this case, the driver is forced to perform an accelerator operation for correcting the vehicle speed deviation, and a minute accelerator operation is repeated.

  The present invention has been made to solve the above-described problems, and has as its main object to provide a vehicle control device that reduces the burden on the driver related to accelerator operation during constant speed traveling.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  The invention described in claim 1 is applied to a vehicle including an output adjusting device that adjusts the output of the internal combustion engine, and a transmission that adjusts the speed ratio of the speed change mechanism that transmits the output to the drive wheels. Then, the target acceleration of the vehicle is set based on the driver's accelerator operation amount, and the feedback adjustment control is performed by controlling the output adjusting device and the transmission so that the actual acceleration of the vehicle matches the target acceleration. To do. According to such a configuration, acceleration responsiveness to accelerator operation can be improved.

  Further, the dead zone of the acceleration feedback control is set in a region near the accelerator operation amount based on the accelerator operation amount when the vehicle is traveling at a constant speed. Therefore, even if an inadvertent accelerator operation is performed by the driver while the vehicle is traveling at a constant speed, as long as the accelerator operation amount after the operation is within the dead zone region, acceleration feedback control based on the accelerator operation is performed. Not implemented. Thereby, the shift | offset | difference of the vehicle speed resulting from careless accelerator operation when the vehicle is drive | working at fixed speed can be suppressed.

  In the invention according to claim 2, when the target acceleration set based on the accelerator operation amount at each time is 0 or a value close to 0, the dead zone of acceleration feedback control is set based on the accelerator operation amount at that time. Set. Here, the target acceleration being 0 or a value close to 0 means that the vehicle speed is maintained by the acceleration feedback process. Therefore, according to the above-described configuration, the dead zone can be set in the vicinity of the accelerator operation amount at that time while the vehicle is traveling at a constant speed, that is, the accelerator operation amount is substantially constant.

  Here, if the width of the dead zone is increased, the amount of operation after inadvertent accelerator operation when the vehicle is traveling at a constant speed will surely be included in the dead zone. The burden on the accelerator operation can be effectively reduced. However, when the width of the dead zone is increased, the operation amount after the accelerator operation intended by the driver is included in the dead zone, so that the acceleration response to the accelerator operation is reduced. Therefore, in order to improve the drivability of the vehicle comprehensively, it is necessary to set the width of the dead zone in consideration of the balance between the driver's burden reduction effect and the influence of the acceleration responsiveness reduction.

  Therefore, in the invention described in claim 3, the width of the dead zone of the acceleration feedback control is set differently on the increase side and the decrease side of the accelerator operation amount. In the invention according to claim 4, the width of the dead zone of the acceleration feedback control is variably set based on the speed of the vehicle every time. According to the fifth aspect of the present invention, the acceleration characteristic preliminarily defining the relationship between the accelerator operation amount and the target acceleration is provided for each of the plurality of operation modes, and the target acceleration is set using the acceleration characteristics of the set operation mode. Control the vehicle to set as follows. That is, the dead zone width of the acceleration feedback control is variably set based on each operation mode.

  In this way, by setting the width of the dead zone in consideration of the balance described above based on the accelerator operation amount (increase / decrease side), the speed of each vehicle, and the acceleration characteristics of each operation mode, the drivability of the vehicle is improved. It can be improved comprehensively.

  According to the sixth aspect of the present invention, when the accelerator operation amount is in the dead zone region, the acceleration feedback control is performed with the target acceleration set to 0 regardless of the accelerator operation amount at that time. Therefore, even if an inadvertent accelerator operation is performed while the vehicle is traveling at a constant speed, the actual acceleration of the vehicle is reduced to 0 by the acceleration feedback control as long as the accelerator operation amount after the operation is in the dead zone region. Maintained. Thereby, even if the acceleration feedback control is continued in the dead zone of the acceleration feedback control, it is possible to suppress the occurrence of a vehicle speed deviation due to an inadvertent accelerator operation when the vehicle is traveling at a constant speed.

  According to the seventh aspect of the invention, when the accelerator operation amount is in the dead zone region, the vehicle speed feedback control is performed to make the actual vehicle speed of the vehicle coincide with the target vehicle speed instead of the acceleration feedback control. Therefore, even if an inadvertent accelerator operation is performed while the vehicle is traveling at a constant speed, the vehicle travels at a constant speed by vehicle speed feedback control as long as the amount of accelerator operation after the operation is within the dead zone region. . As a result, even when the vehicle is traveling at a constant speed, even if the vehicle speed is shifted due to disturbances caused by factors other than changes in the accelerator operation amount, that is, changes in the gradient of the travel path, according to acceleration feedback, The occurrence of the vehicle speed deviation due to the prepared accelerator operation can be suppressed.

  In this vehicle speed feedback control, the vehicle speed at the time when the accelerator operation amount enters the dead zone region is set as the target vehicle speed, and the actual vehicle speed is preferably matched with the target vehicle speed. Then, the vehicle speed does not become discontinuous when switching from the acceleration feedback control to the vehicle speed feedback control, and the driver does not feel uncomfortable due to a change in the vehicle speed.

  The invention according to claim 8 is applied to a vehicle including a transmission (continuously variable transmission) capable of continuously adjusting a transmission gear ratio of the transmission mechanism. As such a vehicle control device, one that performs fuel efficiency optimum line control in acceleration feedback control is known. Here, the fuel efficiency optimal line control is a calculation of a target output (power) of the internal combustion engine required to make the actual acceleration coincide with the target acceleration, and an operating condition (torque defined by the fuel efficiency optimal line based on the target output. And the rotation speed). The electronic throttle device and the continuously variable transmission are controlled to operate the internal combustion engine under the above operating conditions. According to such fuel efficiency optimal line control, the fuel efficiency of the vehicle can be increased.

  However, in the fuel efficiency optimal line control, since the rotational speed of the internal combustion engine is defined by the fuel efficiency optimal line, when the vehicle speed increases to some extent, the rotational speed of the internal combustion engine hardly changes with respect to the change in the vehicle speed (FIG. 8 ( a) (See the graph shown by the solid line). Therefore, it is impossible to correct the vehicle speed by relying on the change in the operation sound (engine sound) accompanying the change in the rotational speed of the internal combustion engine. In this case, the driver needs to correct the vehicle speed, for example, by operating the accelerator while viewing the vehicle speedometer.

  In this regard, in the present invention, as described above, it is possible to suppress the deviation of the vehicle speed caused by an inadvertent accelerator operation when the vehicle is traveling at a constant speed. That is, even when the vehicle speed cannot be easily corrected by performing the fuel efficiency optimal line control, the burden on the driver regarding the accelerator operation can be reduced by suppressing the occurrence of the vehicle speed deviation itself.

  Note that a vehicle having a multi-stage automatic transmission may have the same problem as a vehicle having the continuously variable transmission. That is, in a vehicle equipped with a multi-stage automatic transmission, the vehicle speed and the engine speed at the same gear ratio show a proportional relationship, but the change in the engine speed with respect to the vehicle speed decreases as the gear ratio increases (FIG. 8B). ) Refer to the graph indicated by the solid line). Therefore, when the vehicle speed increases, it is not easy to correct the vehicle speed by relying on changes in engine sound.

  Here, in general, the driver expects that the acceleration response to the accelerator operation decreases on the acceleration side and increases on the deceleration side during traveling on the uphill road. On the other hand, during traveling on a downhill road, it is expected that the acceleration response to the accelerator operation will be higher on the acceleration side and lower on the deceleration side.

Therefore, in the invention according to claim 9, when the gradient of the traveling road is detected and the accelerator operation amount is outside the dead zone region, the target acceleration is reduced when the uphill is detected, and the target acceleration is detected when the downhill is detected. Increase the correction. As a result, on the uphill road, the acceleration response to the accelerator operation decreases on the acceleration side and increases on the deceleration side. On the downhill road, on the other hand, the acceleration response to the accelerator operation increases on the acceleration side and decreases on the deceleration side. Thus, by making the acceleration response expected by the driver correspond to the actual acceleration response of the vehicle, the driver's uncomfortable feeling related to the acceleration response can be reduced.

The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

  The present invention can be specified not only as an apparatus invention but also as a program invention, a recording medium recording the program, and a method invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the vehicle control system of the present embodiment, vehicle travel control is performed on a vehicle on which a multi-cylinder engine and a continuously variable transmission are mounted.

  First, a schematic configuration of the entire system will be described with reference to FIG. An intake pipe 12 of an engine 11 serving as an internal combustion engine is equipped with a throttle valve 14 whose opening is adjusted by a motor 13 and a throttle opening sensor 15 for detecting the opening (hereinafter referred to as “throttle opening”). A throttle device 16 is provided. The electronic throttle device 16 corresponds to an “output adjustment device”.

  Further, on the downstream side of the throttle valve 14, an intake pipe pressure sensor 17 for detecting the intake pipe pressure and an intake air temperature sensor 18 for detecting the intake air temperature are provided, respectively, in the vicinity of the intake port of the intake manifold 19 of each cylinder. A fuel injection valve 20 for injecting fuel is attached. A spark plug 21 is attached to the cylinder head of the engine 11 for each cylinder. The air-fuel mixture in the cylinder is ignited by the spark discharge of the spark plug 21.

  An input shaft 27 of a belt-type continuously variable transmission 26 is connected to the crankshaft 22 of the engine 11 via a forward / reverse switching mechanism 23 and a torque converter 25. The torque converter 25 includes a lockup clutch 24 that mechanically connects or releases the crankshaft 22 and the input shaft 27. And the wheel is connected with the output shaft 28 of the continuously variable transmission 26 via the differential gear apparatus, the drive shaft, etc. which are not shown in figure.

  The speed change mechanism of the continuously variable transmission 26 includes a primary pulley 29 provided to be rotatable integrally with the input shaft 27, a secondary pulley 30 provided to be rotatable integrally with the output shaft 28, and the like. The belt 31 is stretched between pulleys 29 and 30. The primary pulley 29 has a fixed flange portion 29a and a movable flange portion 29b. The secondary pulley 30 has a fixed flange portion 30a and a movable flange portion 30b. The movable flange portions 29b and 30b are movable in the axial direction with respect to the fixed flange portions 29a and 30a, respectively, by hydraulic pressure. The movement of the movable flange portions 29b and 30b changes the width of the V-groove that sandwiches the belt 31.

  When the movable flange portion 29b of the primary pulley 29 is moved so that the width of the V-groove becomes narrow, the winding radius of the belt 31 of the primary pulley 29 increases. On the other hand, since the length of the belt 31 is constant, the movable flange portion 30b of the secondary pulley 30 moves in the direction in which the width of the V-groove becomes wider. As a result, the winding radius of the belt 31 of the secondary pulley 30 is reduced.

  On the other hand, when the movable flange portion 29b of the primary pulley 29 is moved so that the width of the V-groove becomes wider, the winding radius of the belt 31 of the primary pulley 29 becomes smaller. Therefore, the movable flange portion 30b of the secondary pulley 30 moves in the direction in which the width of the V-groove becomes narrow, and the winding radius of the belt 31 of the secondary pulley 30 increases. In this way, the continuously variable transmission 26 continuously changes the wrapping radius of the belt 31 of each pulley 29, 30 by adjusting the V groove width of the primary pulley 29, thereby continuously changing the gear ratio of the transmission mechanism. Can be changed.

  A rotation speed sensor 37 for detecting the rotation speed of the input shaft 27 (hereinafter referred to as “primary rotation speed”) is provided on the input shaft 27 side of the continuously variable transmission 26, and on the output shaft 28 side of the continuously variable transmission 26. Is provided with a rotational speed sensor 38 for detecting the rotational speed of the output shaft 28 (hereinafter referred to as “secondary rotational speed”). The gear ratio of the continuously variable transmission 26 is calculated based on the output signals of the rotation speed sensors 37 and 38. Further, the actual vehicle speed is calculated based on the detection signal of the rotational speed sensor 37 on the input shaft 27 side or the rotational speed sensor 38 on the output shaft 28 side.

  A crank angle sensor 39 is attached to the engine 11. The crank angle sensor 39 outputs a pulse signal every time the crankshaft 22 rotates by a predetermined crank angle. Based on the output signal of the crank angle sensor 39, the crank angle position and the engine speed are calculated.

  On the other hand, an accelerator sensor 41 for detecting an accelerator operation amount is provided in the vicinity of the accelerator pedal 40, a brake switch 43 for detecting a brake operation is provided in the vicinity of the brake pedal 42, and in the vicinity of the shift lever 44. A shift sensor 45 for detecting the operation position of the shift lever 44 is provided. The vehicle is also provided with a gradient sensor 46 that detects the gradient of the travel path. The gradient sensor 46 corresponds to “gradient detection means”. These sensors are connected to the ECU 50.

  The ECU 50 is an electronic control unit mainly composed of a well-known microprocessor having a CPU, a memory, and the like. The memory stores various programs and parameters. The CPU controls the vehicle control system by executing various vehicle control programs stored in the memory. For example, the ECU 50 performs feedback control of vehicle acceleration (hereinafter referred to as “acceleration F / B control”) in order to make the actual acceleration of the vehicle coincide with the target acceleration.

  Next, the acceleration F / B control will be described with reference to FIG. FIG. 2 is a flowchart showing the flow of the acceleration F / B control program. The ECU 50 executes the acceleration F / B control by executing this program at a predetermined cycle (every predetermined crank angle or at a predetermined time cycle). In the following description, it is assumed that the lockup clutch 24 is in the lockup state, and the engine rotation speed and the primary rotation speed are equal.

  The ECU 50 first calculates a target value (hereinafter referred to as “target output”) of the output of the engine 11 by feedback calculation based on the deviation between the actual acceleration of the vehicle and the target acceleration (see step S10). The process for calculating the actual acceleration and the target acceleration will be described later.

  Next, the ECU 50 calculates a target value of torque generated by the combustion of the engine 11 (hereinafter referred to as “target torque”) and a target value of engine speed (hereinafter referred to as “target primary rotational speed”) from the target output (step). (See S11). Specifically, an operation condition for setting the output of the engine 11 as a target output is selected from the operation conditions (engine torque and engine speed) defined by the fuel efficiency optimum line shown in FIG. Specifically, the engine torque at the intersection of the iso-output line corresponding to the target output and the fuel efficiency optimum line is set as the target torque, and the engine rotation speed at the intersection is set as the target primary rotation speed.

  Next, the ECU 50 calculates the target value of the throttle opening based on the target torque (see step S12), and calculates the target value of the speed ratio of the transmission mechanism based on the target primary rotation speed (see step S13). According to such vehicle traveling control by acceleration F / B control, acceleration response to accelerator operation can be improved while improving fuel efficiency.

Here, in the vehicle travel control based on the acceleration F / B control, the following inconvenience may occur.
(1) Since the acceleration response to the accelerator operation is high, if the inadvertent accelerator operation is performed while the vehicle is traveling at a constant speed, the vehicle is accelerated or decelerated even if the operation is slight. As a result, the vehicle speed deviates against the driver's intention.
(2) When the target acceleration is set regardless of the gradient of the traveling road, the acceleration responsiveness to the accelerator operation regardless of whether it is an uphill road or a downhill road as a result of acceleration F / B control based on the target acceleration. Are substantially the same. On the other hand, the driver expects the acceleration response to the accelerator operation to decrease on the acceleration side and increase on the deceleration side when traveling on the uphill road. Further, during traveling on a downhill road, it is expected that the acceleration response to the accelerator operation will be higher on the acceleration side and lower on the deceleration side. Thus, since the actual acceleration response of the vehicle is different from the expected acceleration response, the driver feels uncomfortable.

  Therefore, in the vehicle travel control of the present embodiment, as a countermeasure of the above (1), a dead zone of acceleration F / B control is provided in a region near the accelerator operation amount on the basis of the accelerator operation amount when the vehicle is traveling at a constant speed. Set. When the accelerator operation amount is within the dead zone, vehicle speed feedback control (hereinafter referred to as “vehicle speed F / B control”) is performed. Here, in the vehicle speed F / B control, the target output of the engine 11 is calculated by feedback calculation based on the deviation between the actual vehicle speed and its target value (hereinafter referred to as “target vehicle speed”), and the target torque and target primary are calculated from the target output. This is done by calculating the rotation speed.

  Further, in the vehicle travel control of the present embodiment, as a countermeasure of the above (2), a gradient correction process is performed on the target acceleration of the acceleration F / B control described above. Here, the gradient correction process is a process of correcting the target acceleration to be decreased when the traveling road is an uphill road and increasing the target acceleration when the traveling road is a downhill road.

  Hereinafter, the vehicle travel control of the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of the vehicle travel control program. The ECU 50 performs the vehicle travel control by executing this program at a predetermined cycle (every predetermined crank angle or at a predetermined time cycle). First, the ECU 50 determines whether or not a vehicle speed F / B control execution flag is set (see step S20).

  If it is determined in step S20 that the vehicle speed F / B control execution flag is not set (the vehicle speed F / B control execution flag is reset), the ECU 50 executes the process of step S21. In step S21, the target acceleration ACtrg is calculated based on the accelerator operation amount and the actual vehicle speed.

  The calculation process of the target acceleration ACtrg will be described in detail. First, the accelerator operation amount is detected based on the detection signal of the accelerator sensor 41. Next, the primary rotational speed is calculated from the detection signal of the rotational speed sensor 37 on the input shaft 27 side, the secondary rotational speed is calculated based on the primary rotational speed and the transmission gear ratio, and the secondary rotational speed per unit time is calculated. The actual acceleration is calculated from the amount of change. The secondary rotational speed may be calculated from the detection signal of the rotational speed sensor 38 on the output shaft 28 side, and the actual acceleration may be calculated from the amount of change per unit time of the rotational speed.

  Then, with reference to an acceleration characteristic map (see FIG. 5) using the accelerator operation amount and the vehicle speed as parameters, the target acceleration is obtained from the accelerator operation amount and the actual vehicle speed at that time. In this acceleration characteristic map, the target acceleration is set to a larger value as the accelerator operation amount is larger or the vehicle speed is lower.

  In step S22, the ECU 50 determines whether or not the absolute value of the target acceleration ACtrg is equal to or less than a predetermined value A1 (whether or not the vehicle is traveling at a constant speed).

  If it is determined in step S22 that the absolute value of the target acceleration ACtrg is greater than the predetermined value A1 (that the vehicle is traveling at a constant speed), the ECU 50 executes the process of step S23. In step S23, an estimated gradient value indicating the gradient of the traveling road is calculated. Specifically, the estimated gradient value is calculated from the detection signal of the gradient sensor. In the subsequent step S24, the target acceleration ACtrg is corrected based on the estimated gradient value. Specifically, when the estimated slope value indicates an upward slope, the target acceleration ACtrg is decremented according to the slope, and when the estimated slope value indicates a downward slope, the target acceleration ACtrg is determined as the slope. Increase correction according to.

  Specifically, the target acceleration ACtrg is corrected by multiplying the correction coefficient and the target acceleration ACtrg as follows. That is, when the estimated slope value is a positive value indicating an upward slope and the target acceleration ACtrg is a positive value indicating acceleration, the target acceleration ACtrg is multiplied by a correction coefficient smaller than 1 to the target acceleration ACtrg. When it is a negative value indicating deceleration, a correction coefficient larger than 1 is multiplied by the target acceleration ACtrg. As a result, when the target acceleration ACtrg is a positive value, the absolute value is reduced to reduce correction, and when the target acceleration ACtrg is a negative value, the absolute value is increased to decrease. The

  At this time, it is desirable to set the correction coefficient as follows. That is, when the target acceleration ACtrg is a positive value indicating acceleration, it is desirable to decrease the correction coefficient as the absolute value of the gradient estimated value increases, and when the target acceleration ACtrg is a negative value indicating deceleration. It is desirable to increase the correction coefficient as the absolute value of the estimated gradient value increases.

  On the other hand, when the estimated slope value is a negative value indicating a downward slope and the target acceleration ACtrg is a positive value indicating acceleration, the target acceleration ACtrg is multiplied by a correction coefficient larger than 1 to the target acceleration ACtrg. When it is a negative value indicating deceleration, a correction coefficient smaller than 1 is multiplied by the target acceleration ACtrg. As a result, when the target acceleration ACtrg is a positive value, the absolute value is increased to be increased, and when the target acceleration ACtrg is a negative value, the absolute value is increased to be increased. The

  The correction coefficient is preferably set as follows. That is, when the target acceleration ACtrg is a positive value indicating acceleration, it is desirable to increase the correction coefficient as the absolute value of the gradient estimation value increases, and when the target acceleration ACtrg is a negative value indicating deceleration. It is desirable to make the correction coefficient smaller as the absolute value of the estimated gradient value becomes smaller.

  In the following step S25, the ECU 50 executes an acceleration F / B control process so that the actual acceleration matches the target acceleration (see step S25), and returns to the main program process.

  On the other hand, when it is determined in step S22 that the absolute value of the target acceleration ACtrg is equal to or less than the predetermined value A1 (that the vehicle is traveling at a constant speed), the ECU 50 executes the process of step S26. . In step S26, the vehicle speed F / B control execution flag is set. In subsequent steps S27 and S28, the ECU 50 stores the accelerator operation amount ACPstr and the vehicle speed SPstr at that time. In the following step S29, the ECU 50 executes a vehicle speed F / B control process so that the actual vehicle speed matches the vehicle speed SPstr (see step S29), and returns to the main program process.

  On the other hand, when it is determined in step S20 that the vehicle speed F / B control execution flag is set, the ECU 50 executes the process of step S30. In step S30, it is determined whether or not the absolute value of the difference between the accelerator operation amount ACPstr stored in step S27 and the accelerator operation amount ACPreal is equal to or less than a predetermined value A2.

  When it is determined in step S30 that the absolute value of the difference between the accelerator operation amount ACPstr and the accelerator operation amount ACPreal is equal to or less than the predetermined value A2, the ECU 50 performs a vehicle speed F / B control process to match the actual vehicle speed with the vehicle speed SPstr. Is executed (see step S29), and the process returns to the main program.

  On the other hand, when it is determined in step S30 that the absolute value of the difference between the accelerator operation amount ACPstr and the accelerator operation amount ACPreal is larger than the predetermined value A2, the ECU 50 executes the process of step S31. In step S31, the vehicle speed F / B control execution flag is reset. In subsequent step S32, the ECU 50 calculates the target acceleration ACtrg based on the accelerator operation amount and the actual vehicle speed at that time. Next, the ECU 50 executes the above-described gradient correction process (see steps S23 and S24), and executes an acceleration F / B control process (see step S25) so that the actual acceleration matches the target acceleration after the gradient correction. Then, the process returns to the main program.

  According to the processing of steps S20 to S25 and S30 to S32 in FIG. 4 described above, when the vehicle is not traveling at a constant speed, acceleration is performed so that the actual acceleration matches the target acceleration calculated in step S21 or step S32. F / B control is performed. On the other hand, according to the processing of steps S20 to S22 and S26 to S30 in FIG. 4 described above, when the vehicle travels at a constant speed during the execution of the acceleration F / B control (| ACtrg | ≦ A1), the acceleration F / B control. Instead, vehicle speed F / B control is performed so that the actual vehicle speed matches the vehicle speed stored in step S28. In the vehicle speed F / B control, the absolute value of the difference between the accelerator operation amount (accelerator operation amount at the start of the vehicle speed F / B control) ACPstr stored in step S27 and the current accelerator operation amount is greater than the predetermined value A2. Will continue until. On the other hand, if the absolute value of the difference in the accelerator operation amount becomes larger than the predetermined value A2 during the execution of the vehicle speed F / B control, the acceleration F / B control is executed instead of the vehicle speed F / B control. .

  That is, in the present embodiment, as shown in the acceleration characteristic map of FIG. 6, when the vehicle travels at a constant speed, a dead zone for acceleration F / B control is provided in a region near the accelerator operation amount based on the accelerator operation amount ACPstr at that time. (ACPstr−A2 to ACPstr + A2) is set. And vehicle speed F / B control is implemented until the accelerator operation amount for every time comes out of the area of the dead zone.

  According to the embodiment described in detail above, the following excellent effects can be obtained.

  When the vehicle is not traveling at a constant speed, acceleration F / B control is performed. Thereby, the acceleration characteristic with respect to accelerator operation can be improved.

  A dead zone for acceleration F / B control is set in the vicinity of the accelerator operation amount based on the accelerator operation amount (accelerator operation amount ACPstr at the start of vehicle speed F / B control) when the vehicle is traveling at a constant speed. The vehicle speed F / B control is performed when the accelerator operation is in the dead zone region. Thereby, it can suppress that a vehicle speed shift | deviates as a result of the acceleration F / B control based on careless accelerator operation when the vehicle is drive | working at fixed speed.

  Further, the vehicle speed F / B control is performed so that the actual vehicle speed matches the vehicle speed SPstr at the start of the vehicle speed F / B control. As a result, the vehicle speed continues during the transition from the acceleration F / B control to the vehicle speed F / B control. Therefore, it is possible to reduce the driver's uncomfortable feeling related to the change in vehicle speed.

  Further, the target acceleration used for the acceleration F / B control process is corrected based on the gradient of the traveling road. Specifically, the target acceleration is decrementally corrected when the estimated gradient value indicates an ascending gradient, and the target acceleration is increased and corrected when the estimated gradient value indicates a descending gradient. As a result, on the uphill road, the acceleration response to the accelerator operation decreases on the acceleration side and increases on the deceleration side. On the downhill road, on the other hand, the acceleration response to the accelerator operation increases on the acceleration side and decreases on the deceleration side. In this way, the driver's uncomfortable feeling related to the acceleration response can be reduced by matching the acceleration response expected by the driver on the uphill or downhill with the actual acceleration response.

  Further, when the estimated gradient value indicates an upward gradient and the target acceleration indicates acceleration, the correction coefficient smaller than 1 is reduced as the absolute value of the estimated gradient value increases. As a result, the acceleration response on the acceleration side decreases as the slope of the uphill road increases. Further, when the estimated gradient value indicates an upward gradient and the target acceleration indicates deceleration, a correction coefficient larger than 1 is increased as the absolute value of the estimated gradient value increases. Thereby, the acceleration response on the deceleration side increases as the slope of the uphill road increases.

  Further, when the estimated slope value indicates a downward slope and the target acceleration indicates acceleration, the correction coefficient larger than 1 is increased as the absolute value of the estimated slope value increases. As a result, the acceleration response on the acceleration side increases as the slope of the downhill road increases. Further, when the estimated gradient value indicates a downward gradient and the target acceleration indicates deceleration, the correction coefficient smaller than 1 is made smaller as the absolute value of the estimated gradient value becomes smaller. As a result, the acceleration response on the deceleration side decreases as the slope of the downhill road increases.

  Thus, by making the acceleration response that the driver expects according to the magnitude of the gradient of the traveling road correspond to the actual acceleration response, the driver's uncomfortable feeling related to the acceleration response can be further reduced.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, the amount of increase (ACPstr-A2 to ACPstr) and the amount of decrease based on the accelerator operation amount (accelerator operation amount ACPstr at the start of vehicle speed F / B control) when the vehicle is traveling at a constant speed. A dead zone was set in the side area (ACPstr to ACPstr + A2) (see FIG. 6). However, a dead zone may be set on either the increase side or the decrease side based on the accelerator operation amount when the vehicle is traveling at a constant speed.

  In the above embodiment, the width of the dead zone of the acceleration F / B control is set to be the same (A2) on the increase side and the decrease side of the accelerator operation amount. However, these widths may be set differently. For example, by increasing the dead zone width on the accelerator operation amount increase side relatively, the acceleration response to the acceleration side accelerator operation is lowered, and the accelerator operation amount decrease side dead zone width is relatively reduced. Thus, it is conceivable to suppress a decrease in acceleration responsiveness to the accelerator operation on the deceleration side. In this case, since the vehicle is difficult to accelerate and decelerate easily with respect to the accelerator operation, the safety of the vehicle travel can be improved while reducing the driver's burden on the accelerator operation during constant speed travel.

Moreover, in the said embodiment, although the dead zone was made into the fixed width | variety (A2x2), you may set the width of a dead zone based on each vehicle speed. Here, in general, the lower the vehicle speed, the lower the gear ratio of the transmission mechanism of the continuously variable transmission 26 and the higher the axle torque. Therefore, the lower the vehicle speed, the higher the acceleration response to the accelerator operation. Therefore, for example, it is conceivable to relatively increase the width of the dead zone for acceleration F / B control as the vehicle speed decreases. As a result, it is possible to suppress the occurrence of a shift in vehicle speed due to an inadvertent accelerator operation when the vehicle is traveling at a constant speed while suppressing a decrease in the acceleration response of the vehicle. When the present invention is applied to a vehicle that has an acceleration characteristic that preliminarily defines a relationship between the target acceleration and a plurality of operation modes and sets the target acceleration using the acceleration characteristics of the set operation mode, You may set the width | variety of the dead zone of acceleration F / B control based on each driving | operation mode. For example, in the case of having a sports driving mode in which acceleration response performance is prioritized and a normal driving mode in which fuel efficiency is prioritized, the dead zone in the sports driving mode is reduced to increase acceleration response, and the dead zone in the normal driving mode. By increasing, the driver's burden on the accelerator operation can be reduced during constant speed travel.

  In the above embodiment, the vehicle speed F / B control is performed when the accelerator operation amount is in the dead zone region. However, when the accelerator operation amount is in the dead zone, the acceleration F / B control may be performed with the target acceleration set to 0 regardless of the accelerator operation amount. As a result, even if the acceleration F / B control is continued, the acceleration F / B control is performed so that the actual acceleration is zero, which is caused by an inadvertent accelerator operation when the vehicle is traveling at a constant speed. The occurrence of a shift in vehicle speed can be suppressed.

  In the above embodiment, it is determined whether or not the accelerator operation amount is within the dead zone region based on the accelerator operation amount (see step S30 shown in FIG. 4). However, this determination process may be executed based on the target acceleration. For example, in step S30, as shown in FIG. 7, when the absolute value of the target acceleration at that time is larger than a predetermined value A3, it is determined that the accelerator operation amount at that time is outside the dead zone region, If the absolute value of the target acceleration at that time is equal to or less than the predetermined value A3, it may be determined that the accelerator operation amount at that time is within the dead zone region.

  In the above embodiment, when it is determined in step S22 that the absolute value of the target acceleration ACtrg is equal to or less than the predetermined value A1, the vehicle speed F / B control is shifted to. However, when it is determined a plurality of times that the absolute value of the target acceleration ACtrg is equal to or less than the predetermined value A1, the vehicle speed F / B control may be shifted to.

  Further, in the above embodiment, when it is determined in step S30 that the absolute value of the difference between the accelerator operation amount ACPstr and the accelerator operation amount ACPreal is larger than the predetermined value A2, the process proceeds to acceleration F / B control. I made it. However, when it is determined that the absolute value of the difference between the accelerator operation amount ACPstr and the accelerator operation amount ACPreal is greater than the predetermined value A2 a plurality of times in succession, the process may proceed to acceleration F / B control. .

  Moreover, in the said embodiment, although the vehicle provided with the continuously variable transmission 26 as a transmission was made into the control object, it is good also considering the vehicle provided with a multistage automatic transmission as a control object.

  Moreover, in the said embodiment, the gradient correction process (refer step S24, 25 shown in FIG. 4) was performed in vehicle travel control. However, this process may be omitted.

  In the above embodiment, a vehicle including the electronic throttle device 16 as an output adjusting device is a control target, and the output of the engine 11 is controlled by the throttle opening of the electronic throttle device 16. However, a vehicle including a mechanism for freely controlling the opening / closing timing of the intake valve and its lift amount may be controlled, and the output of the engine may be controlled based on the timing and lift amount.

The figure which shows the structure of an engine control system. The flowchart which shows the flow of an acceleration feedback control program. The figure which shows the relationship between an engine output, an engine torque, and an engine speed. The flowchart which shows the flow of a vehicle travel control program. The figure which shows the relationship between accelerator operation and vehicle speed, and target acceleration. The figure for demonstrating the dead zone of acceleration F / B control. The figure for demonstrating the dead zone of acceleration F / B control. The figure which shows the relationship between a vehicle speed and an engine speed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 16 ... Electronic throttle device (output adjustment device), 23 ... Forward / reverse switching mechanism, 24 ... Lock-up clutch, 25 ... Torque converter, 26 ... Continuously variable transmission (transmission), 29 ... Primary pulley (transmission mechanism), 30 ... secondary pulley (transmission mechanism), 31 ... belt (transmission mechanism), 37 (transmission mechanism), 38 ... rotational speed sensor, 40 ... accelerator pedal, 41 ... accelerator sensor, 46 ... gradient sensor (Gradient detecting means), 50... ECU (dead zone setting means, means for performing acceleration feedback control, means for performing vehicle speed feedback control, gradient detecting means, gradient correcting means).

Claims (9)

Applied to a vehicle having an output adjusting device that adjusts the output of the internal combustion engine and a transmission that adjusts the speed ratio of the speed change mechanism that transmits the output of the internal combustion engine to the drive wheel side, and the amount of accelerator operation for each driver In the vehicle control device for setting the target acceleration of the vehicle on the basis of the control value and controlling the output adjusting device and the transmission to perform the acceleration feedback control so that the actual acceleration of the vehicle matches the target acceleration. ,
A vehicle control apparatus comprising: dead zone setting means for setting a dead zone for the acceleration feedback control in a region near the accelerator operation amount with reference to an accelerator operation amount when the vehicle is traveling at a constant speed. .   The dead zone setting means sets the dead zone based on the accelerator operation amount at that time when the target acceleration set based on the accelerator operation amount for each time is 0 or a value close to 0. The vehicle control device described.   3. The vehicle control device according to claim 1, wherein the dead zone setting means sets the width of the dead zone differently on an increase side and a decrease side of an accelerator operation amount. 4.   4. The vehicle control device according to claim 1, wherein the dead zone setting unit sets the width of the dead zone variably based on the speed of the vehicle each time. 5. The vehicle control device that has an acceleration characteristic that predetermines a relationship between an accelerator operation amount and the target acceleration for each of a plurality of driving modes, and sets the target acceleration using the acceleration characteristics of the set driving mode. In
5. The vehicle control device according to claim 1, wherein the dead zone setting unit variably sets the width of the dead zone based on each driving mode.   6. The apparatus according to claim 1, further comprising: means for performing the acceleration feedback control with the target acceleration set to 0 regardless of the accelerator operation amount at that time when the accelerator operation amount is in the dead zone region. The vehicle control device described in 1.   6. The apparatus according to claim 1, further comprising means for performing vehicle speed feedback control so that an actual vehicle speed of the vehicle coincides with a target vehicle speed instead of the acceleration feedback control when an accelerator operation amount is in the dead zone region. The vehicle control device according to any one of the above.   The vehicle control device according to claim 1, wherein the vehicle control device is applied to the vehicle including the transmission capable of continuously adjusting a gear ratio of the transmission mechanism. A gradient detecting means for detecting the gradient of the traveling path;
When the accelerator operation amount is outside the dead zone region, the target acceleration is de-corrected when the gradient detecting means detects an upward gradient, and when the gradient detecting means detects the downward gradient, the target acceleration is reduced. The vehicle control device according to any one of claims 1 to 8, further comprising gradient correction means for increasing correction.

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