JP2006274962A - Driving force control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force control device for a vehicle improving acceleration feeling of a driver in a step-on process of accelerator pedal. <P>SOLUTION: Vehicle-demand driving force Fd is calculated according to a predetermined function 190 using accelerator opening xa as a parameter reflecting accelerator pedal step-on action of the diver. The predetermined function 190 is established to have an inflection point 195 in relation to a reference straight line 170 connecting a zero point of accelerator opening (xa=0%) and a full open point (xa=100%). Moreover, the predetermined function 190 has a convex form in relation to the reference straight line 170 in a zone where accelerator opening xa is larger than the inflection point 195, and has a concave shape in relation to the reference straight line 170 in a zone where accelerator opening xa is smaller than the inflection point 195. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle driving force control device, and more particularly to a vehicle driving force control device that calculates a required driving force of a vehicle according to an accelerator opening.

  In automobiles, the driver's intention to accelerate is reflected in the amount of accelerator pedal depression. Therefore, in an automobile equipped with an electronic control unit, the accelerator opening corresponding to the amount of depression of the accelerator pedal is detected, and the required driving force of the vehicle is calculated according to the accelerator opening. Furthermore, it is necessary to control a vehicle driving force generation source such as an engine or a motor so that the calculated required driving force is output.

Therefore, in order to drive the vehicle according to the driver's acceleration request, a configuration for accurately calculating the required driving force of the vehicle according to the accelerator opening is required. For example, in Japanese Patent Laid-Open No. 2002-171778 (Patent Document 1), in a hybrid vehicle, a target torque of a motor that generates a vehicle driving force according to a predetermined function having an upward convex shape is set according to an increase in accelerator opening. The structure to perform is disclosed.
JP 2002-171778 A

  However, when the driver tries to accelerate the vehicle, an operation is performed in which the accelerator pedal is depressed in accordance with the response of the vehicle until the expected acceleration is reached. For this reason, if the calculation of the required driving force to the vehicle with respect to the accelerator opening is inappropriate, the driver may not obtain the acceleration feeling expected and may impair driving comfort.

  In particular, according to the accelerator opening-vehicle driving force (target torque) setting characteristic as disclosed in FIG. 3 of Patent Document 1, in a region where the accelerator opening is relatively small, the target torque is increased as the accelerator opening increases. (Vehicle driving force) increases, but in a region where the accelerator opening is large, where the driver's intention to accelerate is clearly expressed, the increase in target torque (vehicle driving force) with respect to the increase in accelerator opening becomes dull. It is expected that the feeling of acceleration that the person expects cannot be obtained.

  The present invention has been made in order to solve such problems, and an object of the present invention is to provide a vehicle driving force control device that improves the vehicle acceleration feeling in the accelerator depression process of the driver. That is.

  A vehicle driving force control device according to the present invention is a vehicle driving force control device that receives an acceleration instruction operation of a driver by an accelerator pedal, and includes an accelerator opening detection means, a driving force calculation means, and a drive control means. Prepare. The accelerator opening detecting means detects the accelerator opening corresponding to the operation amount to the accelerator pedal. The driving force calculation means calculates the required driving force of the vehicle according to the accelerator opening. The drive control means controls the vehicle so as to generate the driving force calculated by the driving force calculation means. In particular, the driving force calculation means calculates the required driving force according to a predetermined function defined on a plane having the accelerator opening as the horizontal axis and the required driving force of the vehicle as the vertical axis. Here, the predetermined function is determined so as to have an inflection point with respect to a reference straight line connecting between the zero point and the fully open point of the accelerator opening on the predetermined function. Furthermore, the predetermined function is convex upward in the region where the accelerator opening is larger than the inflection point, while the predetermined function is the reference in the region where the accelerator opening is smaller than the inflection point. It is determined to be convex downward with respect to the straight line.

  According to the vehicle driving force control device described above, in a region where the accelerator opening is smaller than the inflection point, the predetermined function is convex downward with respect to the reference straight line so that the vehicle driving force according to the increase in the accelerator opening is increased. On the other hand, in a region where the driver's intention to accelerate is larger than the inflection point and the driver's intention to accelerate is clear, the predetermined function is raised upward to increase the amount of vehicle driving force with respect to the increase in accelerator opening. It is getting bigger. As a result, even if the accelerator opening is increased beyond the clear inflection point by the driver, the driving force of the vehicle can be increased in response to the increase in the accelerator opening. The jerk (acceleration time derivative) of the vehicle can be increased in accordance with the increase in. Thereby, a driver | operator can make a driver | operator feel more clearly in the driver | operator's accelerator depression process.

  Preferably, in the vehicle driving force control apparatus according to the present invention, the inflection point is set in a region where the accelerator opening is 20% or more with respect to the fully opened state.

  According to the driving force control apparatus for a vehicle described above, a sufficient acceleration feeling can be given to the driver in the accelerator opening range where the driver's intention to accelerate is clear.

  Preferably, in the vehicle driving force control apparatus according to the present invention, the predetermined function is an inverse function of a cubic function having the accelerator opening as a variable.

  According to the vehicle drive device described above, since the predetermined function can be realized with a lower order as an inverse function of the cubic function, the setting of the predetermined function can be facilitated.

  According to the vehicle driving force control apparatus of the present invention, a sufficient vehicle acceleration feeling can be obtained in the process of the accelerator pedal depression of the driver.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is a block diagram showing a schematic configuration of a hybrid vehicle 100 controlled by a vehicle driving force control apparatus according to the present invention.

  Referring to FIG. 1, hybrid vehicle 100 includes a battery 10, a power conversion unit (PCU: Power Control Unit) 20, an electric motor (motor) 30, an engine 40, a power split mechanism 50, and a generator (generator). ) 60, a transmission 70, drive wheels 80a and 80b, an ECU (Electronic Control Unit) 90 that controls the overall operation of the hybrid vehicle 100, an accelerator pedal device 110, and an accelerator opening sensor 120.

  The battery 10 is composed of a rechargeable secondary battery (for example, a secondary battery such as nickel metal hydride or lithium ion). The power conversion unit 20 includes an inverter (not shown) that converts a DC voltage supplied from the battery 10 into an AC voltage for driving the motor 30. This inverter is configured to be capable of bidirectional power conversion, and the generated power (AC voltage) generated by the regenerative braking operation of the motor 30 and the generated power (AC voltage) generated by the generator 60 are converted into a DC voltage for charging the battery 10. It also has a function to convert.

  Further, power conversion unit 20 may further include a step-up / down converter (not shown) that performs level conversion of a DC voltage. By arranging such a step-up / step-down converter, the motor 30 can be driven by an AC voltage whose amplitude is higher than the supply voltage of the battery 10, so that the motor drive efficiency can be improved.

  The engine 40 is an internal combustion engine that uses gasoline or the like as fuel, and converts thermal energy generated by combustion of the fuel into kinetic energy that serves as a driving force and outputs the kinetic energy. Power split device 50 can divide the output from engine 40 into a path for transmitting to drive wheels 80 a and 80 b via transmission 70 and a path for transmitting to generator 60. The generator 60 is rotated by the output from the engine 40 transmitted through the power split mechanism 50 to generate electric power. The power generated by the generator 60 is used by the power converter 20 as charging power for the battery 10 or driving power for the motor 30.

  The motor 30 is rotationally driven by the AC voltage supplied from the power converter 20, and the output is transmitted to the drive wheels 80 a and 80 b via the transmission 70. Further, during the regenerative braking operation in which the motor 30 is rotated as the drive wheels 80a and 80b are decelerated, the motor 30 acts as a generator.

  The accelerator pedal device 110 sets an accelerator opening corresponding to the depression force of the accelerator pedal 105 that is depressed by the driver. The accelerator opening sensor 120 is connected to the accelerator pedal device 110 and sends an output voltage corresponding to the accelerator opening xa to the ECU 90.

  In the hybrid vehicle 100, at the time of starting and running at a low speed, or at a light load such as when going down a gentle slope, the output of the engine 30 alone is used without using the output of the engine 40 in order to avoid a region where the engine efficiency is low. Run. That is, in a region where the accelerator opening is small, hybrid vehicle 100 travels with the output of motor 30 alone. In this case, the operation of the engine 40 is stopped except when the warm-up operation is necessary. When warm-up operation is required, the engine 40 is idled.

  On the other hand, during normal travel in which the accelerator opening is larger than a predetermined value, the engine 40 is started, and the output from the engine 40 is generated by the power split mechanism 50 by the driving force of the driving wheels 80a and 80b and the driving force for power generation by the generator 60. And divided. The electric power generated by the generator 60 is used to drive the motor 30. Therefore, during normal traveling, the output from the engine 40 is assisted by the output from the motor 30, and the drive wheels 80a and 80b are driven. The ECU 90 controls the power split ratio by the power split mechanism 50 so that the overall efficiency is maximized.

  Further, at the time of high acceleration, the electric power supplied from the battery 10 is further used for driving the motor 30, and the driving force of the driving wheels 80a and 80b is further increased.

  During deceleration and braking, the motor 30 is rotationally driven by the drive wheels 80a and 80b to generate electric power. The electric power recovered by the regenerative power generation of the motor 30 is converted into a DC voltage by the power conversion unit 20 and used for charging the battery 10. Further, when the vehicle is stopped, the engine 40 is automatically stopped.

  In the hybrid vehicle 100, the required vehicle driving force corresponding to the operation of the accelerator pedal by the driver is satisfied by the combination of the output from the engine 40 and the output from the motor 30 using electric energy as a source. That is, the vehicle operation with improved fuel efficiency is performed by controlling the operation of the engine 40 and the motor 30 in accordance with vehicle requirements.

  FIG. 2 is a schematic block diagram illustrating functional parts corresponding to the vehicle driving force control device according to the accelerator opening by the ECU 90.

  Referring to FIG. 2, driving force control device 150 includes a required driving force calculation unit 155 and a driving force control unit 160.

  The required driving force calculation unit calculates the required driving force Fd of the vehicle according to the accelerator opening xa from the accelerator opening sensor 120. The driving force control unit 160 calculates the output power of the entire hybrid vehicle 100 according to the required driving force Fd calculated by the required driving force calculation unit 155 and the current vehicle speed, and performs distribution control of the total output power. Do. That is, the driving force control unit 160 issues a throttle opening command to an engine ECU (not shown) that controls the operation of the engine 40 so as to satisfy the calculated target output power, and controls the operation of the motor 30. A motor torque command is output to the instructing PCU 20, and a gear ratio command and / or a lock-up command is generated for the transmission 70.

  When the hybrid vehicle 100 operates in accordance with a command from the driving force control unit 160, a vehicle driving force that satisfies the driver's required driving force is obtained.

  FIG. 3 is a diagram illustrating a function used to calculate the required driving force in the required driving force calculation unit 155 shown in FIG.

  The horizontal axis in FIG. 3 indicates the accelerator opening xa, and the vertical axis indicates the required driving force Fd. In FIG. 3, the accelerator opening xa is expressed as a percentage (%) with respect to the fully opened state.

  FIG. 3 shows predetermined function 190 according to the present embodiment used in required driving force calculation unit 155, and functions 170 and 180 shown for comparison.

  Each of the functions 170, 180, and 190 calculates the required driving force Fd corresponding to the accelerator opening xa, with the accelerator opening xa = 0 (%) as the starting point and xa = 100 (%) with respect to the accelerator opening fully opened as the end point. To do.

  At the start point of these functions, that is, xa = 0 (%), the vehicle required driving force Fd is set to a negative value corresponding to the engine brake. Thereafter, each function 170, 180, 190 is set such that the required driving force Fd increases as the accelerator opening xa increases.

  The function 170 corresponds to a “reference straight line” that connects the start point (accelerator opening zero point) and the end point (accelerator opening fully open point) with a straight line. Hereinafter, the function 170 is also referred to as a proportional function 170. According to the proportional function 170, the required driving force Fd is calculated in proportion to the accelerator opening xa.

  Similar to FIG. 3 of Patent Document 1, the function 180 is set to be convex upward with respect to the reference straight line 170 in the entire range of the accelerator opening xa. Hereinafter, the function 180 is also referred to as a conventional function 180.

  On the other hand, the predetermined function 190 according to the embodiment of the present invention is set so as to have an inflection point 195 where the convex direction with respect to the reference straight line changes. Specifically, the predetermined function 190 is convex downward with respect to the reference straight line (function 170) in a region where the accelerator opening xa is smaller than the inflection point 195, while the accelerator function is greater than the inflection point 195. In a region where the opening degree xa is large, it is set to be convex upward with respect to the reference straight line. This inflection point 195 is preferably provided in a region larger than xa = 20 (%), corresponding to the accelerator opening degree that is reached when the driver's intention to accelerate is clear.

  As a result, in the predetermined function 190, in the region where the accelerator opening is smaller than the inflection point 195, the amount of increase in the vehicle driving force corresponding to the increase in the accelerator opening is suppressed. In an area where the opening xa is large and the driver's intention to accelerate is clear, the amount of increase in the vehicle driving force with respect to the increase in the accelerator opening is increased.

  Such a predetermined function 190 can be realized with a minimum order as an inverse function of a cubic function, for example. In this case, the required driving force Fd corresponding to the accelerator opening xa is calculated according to the following equations (1) and (2).

Fd = f ⁻¹ (xa) (1)
f (xa) = a · xa ³ + b · xa ² + c · xa + d (2)
In addition, a to d in the expression (2) are constants and can be adjusted to make the predetermined function 190 have desired characteristics.

  4 and 5 show the simulation results of the vehicle acceleration and jerk (time differential value of acceleration) when the required driving force is calculated according to the functions 170 to 190 shown in FIG.

  4 and 5, in this simulation, the accelerator opening is set to a constant initial value in the period of 0 to 1 (seconds), and the accelerator opening is fully opened from the initial value in the period of 1 to 3 (seconds). It is increased at a constant rate until the state (xa = 100 (%)). In the period of 3 to 5 (seconds), the accelerator opening degree xa is maintained at 100 (%).

  In FIG. 4, the transition of the vehicle acceleration Fa when the required driving force Fd is calculated using the predetermined function 190 in response to the accelerator opening operation indicated by the reference numeral 190x is indicated by the reference numeral 190a. Similarly, reference numeral 170a indicates a transition of the vehicle acceleration Fa when the required driving force Fd is calculated using the proportional function 170 in response to the accelerator opening operation indicated by the reference numeral 170x. A transition of the vehicle acceleration Fa when the required driving force Fd is calculated using the conventional function 180 in response to the accelerator opening operation indicated by reference numeral 180x is shown.

  Note that the accelerator opening initial values (openings in the period of 0 to 1 (second)) at the reference numerals 170x, 180x, and 190x have the same vehicle acceleration Fa at the time of 1 (second) when the functions 170 to 190 are used. It is determined to be a value.

  As can be understood from FIG. 4, when the required driving force Fd is calculated using the conventional function 180 (acceleration transition 180a), a characteristic that the vehicle acceleration Fa increases as the accelerator opening xa increases is obtained. . However, in the acceleration transition 180a, the acceleration increase rate is larger than that in the acceleration transition 190a, and the timing at which the acceleration is saturated is relatively early. Therefore, in the acceleration transition 180a, the acceleration can be increased from the region where the accelerator opening is small, while in the region where the accelerator opening is large, there is a possibility that the acceleration in response to the increase in the accelerator opening cannot be obtained.

  Further, when the required driving force Fd is calculated using the proportional function 170 (acceleration transition 170a), the vehicle acceleration Fa increases as the accelerator opening xa increases, but in a region where the accelerator opening is large, the accelerator The increase in acceleration in response to the increase in opening is dull. For this reason, there is a possibility that the driver cannot obtain an acceleration feeling in response to the accelerator depression.

  On the other hand, when the required driving force Fd is calculated using the predetermined function 190 (acceleration transition 190a), the vehicle acceleration Fa increases substantially proportionally with the increase in the accelerator opening xa in the entire area of the accelerator opening. The characteristics to be obtained are obtained. In particular, by providing an inflection point 195 in the predetermined function 190, an increase in acceleration can be secured in response to an increase in the accelerator opening in a region where the accelerator opening is larger than the inflection point 195. As a result, the driver can feel an appropriate acceleration feeling.

  In FIG. 5, the transition of the vehicle jerk acceleration Fj when the required driving force Fd is calculated using the predetermined function 190 in response to the accelerator opening operation 190x is indicated by reference numeral 190j. Similarly, reference numeral 170j indicates a transition of the vehicle jerk Fj when the required driving force Fd is calculated using the proportional function 170 in response to the accelerator opening operation 170x, and reference numeral 180j indicates the accelerator opening. A transition of the vehicle jerk Fj when the required driving force Fd is calculated using the conventional function 180 in response to the operation 180x is shown. In addition, accelerator opening operation 170x-190x is the same as that of FIG.

  As can be understood from FIG. 5, when the required driving force Fd is calculated using the conventional function 180 (jerk transition 180j), the jerk Fj is saturated in a region where the accelerator opening is small, and the driver's acceleration In a region where the accelerator opening is large and the intention is clear, the jerk Fj decreases on the contrary as the accelerator opening increases.

  Similarly, when the required driving force Fd is calculated using the proportional function 170 (jerk transition 170j), in a region where the accelerator opening is large where the driver's intention to accelerate is clear, jerk associated with the increase in the accelerator opening. The increase in Fj becomes dull.

  For this reason, in the calculation of the required driving force Fd according to the functions 170 and 180, the driver cannot obtain a satisfactory acceleration feeling accompanying an increase in the accelerator opening.

  On the other hand, when the required driving force Fd is calculated using the predetermined function 190 (jerk transition 190j), the jerk Fj is approximately proportional to the increase in the accelerator opening xa in the entire area of the accelerator opening. Increased characteristics. In particular, by providing an inflection point 195 in the predetermined function 190, an increase in jerk can be secured in response to an increase in the accelerator opening in a region where the accelerator opening is larger than the inflection point 195. As a result, the driver can feel a sufficient acceleration feeling.

  In the present embodiment, the calculation of the required driving force in the hybrid vehicle using the engine and the electric motor as the driving force source has been described, but the application of the present invention is not limited to such a form. That is, the calculation of the required driving force according to the accelerator opening is performed according to the present invention even for a hybrid vehicle using a combination of other driving force sources or a vehicle having a single driving force source (only the engine, only the electric motor, etc.). Can be.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a block diagram showing a schematic configuration of a hybrid vehicle controlled by a vehicle driving force control apparatus according to the present invention. FIG. It is a schematic block diagram explaining the functional part corresponding to the vehicle driving force control apparatus according to the accelerator opening by ECU. It is a figure which shows the predetermined function used for calculation of a required driving force. It is a figure which shows the simulation result of the vehicle acceleration at the time of the required driving force calculation according to each function shown in FIG. It is a figure which shows the simulation result of the vehicle jerk (time differential value of acceleration) at the time of request | requirement driving force calculation according to each function shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Battery, 20 Power converter, 30 Electric motor (motor), 40 Engine, 50 Power split mechanism, 60 Generator, 70 Transmission, 80a, 80b Drive wheel, 90 ECU, 100 Hybrid vehicle, 105 Accelerator pedal, 120 Accelerator opening Sensor, 150 Driving force control device, 155 Required driving force calculation unit, 160 Driving force control unit, 170 Proportional function (reference line), 180 Conventional function, 190 Predetermined function (present invention), 170a, 180a, 190a Acceleration transition, 170j , 180j, 190j Jerk transition, 170x, 180x, 190x accelerator opening operation, 195 inflection point, Fd vehicle driving force.

Claims (3)

A driving force control device for a vehicle that receives an acceleration instruction operation of a driver by an accelerator pedal,
An accelerator opening detecting means for detecting an accelerator opening according to an operation amount to the accelerator pedal;
Driving force calculating means for calculating the required driving force of the vehicle according to the accelerator opening;
Drive control means for controlling the vehicle so as to generate the drive force calculated by the drive force calculation means,
The driving force calculating means calculates the required driving force according to a predetermined function defined on a plane having the accelerator opening as a horizontal axis and the required driving force of the vehicle as a vertical axis,
The predetermined function has an inflection point with respect to a reference straight line connecting between a zero point and a full open point of the accelerator opening on the predetermined function, and in a region where the accelerator opening is larger than the inflection point. While the predetermined function is convex upward with respect to the reference straight line, the predetermined function is determined to be convex downward with respect to the reference straight line in a region where the accelerator opening is smaller than the inflection point. A vehicle driving force control device.   2. The vehicle driving force control device according to claim 1, wherein the inflection point is set in a region where the accelerator opening is 20% or more with respect to the fully opened state.   The vehicle driving force control apparatus according to claim 1, wherein the predetermined function is an inverse function of a cubic function having the accelerator opening as a variable.

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