JP4770812B2 - Vehicle motion control device - Google Patents

Description

  The present invention relates to a motion control device that controls a control object related to the motion of a vehicle based on an operation amount of an operation member operated by a driver, and particularly relates to a technique for improving acceleration / deceleration performance.

Patent Document 1 discloses a device that determines a target acceleration of a vehicle based on an accelerator operation amount and controls an opening degree of a throttle valve and the like so that the vehicle travels at the target acceleration.
JP 2006-125213 A

By controlling the vehicle acceleration that the occupant feels as a target value as in Patent Document 1, the driving feeling is improved as compared with control using the engine torque as a target value.
However, as in Patent Document 1, when setting the target acceleration with respect to the accelerator operation amount, the target acceleration (or driving force or torque) is set by map adaptation with the accelerator operation amount and the vehicle speed (or engine speed) as axes. Because people set it empirically, it did not always feel natural for the driver, and sometimes it seemed unnatural.

In addition, the correction required a review of the entire map, which required time and experience.
The present invention has been made paying attention to such a conventional problem, and it is an object of the present invention to provide a natural feeling of operation by appropriately setting a target acceleration for an operation amount of an accelerator or the like. .

  Therefore, the vehicle motion control apparatus according to the present invention includes an operation amount detection means for detecting an operation amount of an operation member operated by a driver to control driving of the vehicle, a target acceleration Atg of the vehicle, and the operation amount x The target acceleration calculation means for calculating with a linear increase function (Atg = S · x + b; S>, b> 0) with the variable as the variable, and the slope S of the primary increase function is larger as the vehicle speed is lower and the vehicle speed is higher. Accelerator sensitivity calculating means for calculating with a function of the vehicle speed V, the rate of decrease of the slope S with respect to the increase in the vehicle speed becomes smaller.

  According to the above configuration, since acceleration is often actively performed in a low speed range such as starting, for example, driving is easier when the slope S of the linear increase function of the target acceleration is relatively high. On the other hand, since the frequency of running at a constant speed increases as the speed increases, driving with a lower slope S is easier. When the speed further increases and the vehicle travels at a high speed, it is not necessary to change the slope S.

  Therefore, the condition in each speed range is satisfied by setting the slope S as a function of the vehicle speed V that increases as the vehicle speed decreases and increases as the vehicle speed increases. Therefore, it is possible to obtain a natural and easy-to-drive characteristic for the driver.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of a vehicle internal combustion engine to which a vehicle motion control apparatus according to the present invention is applied.

  An internal combustion engine 1 shown in FIG. 1 is mounted on an automobile (not shown), and engine generated torque taken out from a crankshaft of the internal combustion engine 1 is transmitted to drive wheels via a transmission.

  The internal combustion engine 1 is a multi-cylinder four-cycle gasoline engine. In each cylinder, air that has passed through an air cleaner 2 is sucked through an intake duct 3, an intake collector 4, an intake manifold 5, and an intake valve 6. The

The intake air amount of the internal combustion engine 1 is adjusted by an electric control throttle 7 interposed in the intake duct 3.
The electric throttle 7 is a mechanism for opening and closing a butterfly throttle valve 7a with a throttle motor (throttle actuator) 7b.

A fuel injection valve 9 is provided in each intake port portion of each cylinder, and fuel (gasoline) is injected into the intake port of each cylinder.
However, the fuel injection valve 9 may be an in-cylinder direct injection internal combustion engine in which fuel is directly injected into the combustion chamber 10.

The fuel injected from the fuel injection valve 9 is ignited and burned by spark ignition by the spark plug 15 in the combustion chamber 10.
Each ignition plug 15 is directly attached with an ignition coil 16 having a built-in power transistor, and the ignition timing and ignition energy of the ignition plug 15 are adjusted by controlling energization to the ignition coil 16. .

The combustion exhaust in the combustion chamber 10 is discharged to the atmosphere via an exhaust valve 11, an exhaust manifold 12, and an exhaust duct 13.
The exhaust duct 13 is provided with a catalytic converter 14 for purifying harmful components in the exhaust.

  The power transistor for controlling energization to the throttle motor 8, the fuel injection valve 9, and the ignition coil 16 is controlled by an engine control unit (ECU) 21 incorporating a microcomputer.

Detection signals from various sensors are input to the engine control unit 21.
The various sensors include an air flow meter 22 that detects the intake air flow rate Qa (mass flow rate) of the internal combustion engine 1 on the upstream side of the electric throttle 7, and an oxygen concentration in the exhaust gas on the upstream side of the catalytic converter 14. An air-fuel ratio sensor 23 for detecting the air-fuel ratio, a rotation speed sensor 24 for detecting the rotation speed Ne of the internal combustion engine 1, and an accelerator operation amount sensor 26 for detecting the depression amount (accelerator operation amount) APS of the accelerator pedal 25 operated by the driver. A throttle sensor 27 for detecting the opening TVO of the throttle valve 7a, a vehicle speed sensor 28 for detecting a traveling speed (vehicle speed) V of the vehicle on which the internal combustion engine 1 is mounted, and the like are provided.

Note that the accelerator operation is not limited to a depression of the accelerator pedal 25, and may be a lever operation, a grip operation, or the like.
The engine control unit 21 controls the fuel injection amount by the fuel injection valve 9 as follows.

  First, from the intake air flow rate Qa detected by the air flow meter 22 and the engine rotational speed Ne detected by the rotational speed sensor 24, a basic for forming a mixture of the target air-fuel ratio at the cylinder intake air amount at that time. A fuel injection amount Tp is calculated.

  Further, various correction coefficients CO are calculated based on the coolant temperature of the internal combustion engine 1 and the air-fuel ratio feedback correction coefficient ALPHA is calculated so that the air-fuel ratio detected by the air-fuel ratio sensor 23 approaches the target air-fuel ratio. The final fuel injection amount Ti is set by correcting the basic fuel injection amount Tp with the correction coefficients CO and ALPHA.

Then, an injection pulse signal having a pulse width corresponding to the final fuel injection amount Ti is output to each fuel injection valve 9 in accordance with the stroke of each cylinder.
The pressure of the fuel supplied to the fuel injection valve 9 is adjusted so that the fuel injection valve 9 injects an amount of fuel proportional to the valve opening time, and the pulse of the injection pulse signal An amount of fuel proportional to the width, that is, the valve opening time of the fuel injection valve 9 is injected.

  The engine control unit 21 calculates an ignition timing (ignition advance value) from the basic fuel injection amount Tp (engine load) and the engine rotational speed Ne, and the ignition control is based on the ignition timing and a predetermined energization time. The on / off control of the power transistor built in the coil 16 is controlled.

Further, the engine control unit 21 controls the intake air amount (output) of the internal combustion engine 1 by controlling the opening degree of the electric control throttle 7.
The flowchart of FIG. 2 shows the main routine of the throttle opening control.

First, in step S1, the target acceleration of the vehicle is calculated from the accelerator operation amount APS.
In step S2, the target tire torque for obtaining the target acceleration calculated in step S1 is calculated from the weight of the vehicle and the running resistance (gradient resistance, air, rolling resistance, etc.).

  In step S3, the target engine torque for obtaining the target tire torque is calculated from the target tire torque, the reduction ratio, the friction of the drive shaft / engine, the moment of inertia of the drive shaft / engine, the auxiliary machine load, and the like.

In step S4, a target average effective pressure (IMEP) for obtaining the target engine torque is calculated.
In step S5, a target intake pressure for obtaining an intake air amount necessary to obtain the target average effective pressure is calculated.

The step S4 can be omitted, and the target intake pressure can be obtained directly from the target engine torque.
In step S6, a target throttle passage intake flow rate for obtaining the target intake pressure is calculated.

In step S7, the target throttle opening area for obtaining the target throttle passage intake flow rate is calculated from the target intake pressure or the detected value of the intake pressure, the atmospheric pressure, and the like.
In step S8, the target throttle opening corresponding to the target throttle opening area is calculated from the correlation between the throttle opening area and the throttle opening stored in advance.

  In step S9, the throttle motor (throttle actuator) 7b is feedback-controlled so that the opening degree of the throttle valve 7a detected by the throttle sensor 27 approaches the target throttle opening degree.

The target acceleration set in step S1 is realized by controlling the throttle valve opening in step S9.
Here, the calculation of the target acceleration in step S1 will be described in detail according to the flowchart of FIG.

In step S11, the accelerator operation amount APS (deg) and the vehicle speed V detected by the accelerator operation amount sensor 26 are input.
Here, the accelerator pedal 25 corresponds to an operation member that the driver operates to control the driving of the vehicle, the accelerator operation amount APS corresponds to the operation amount x of the operation member, and the accelerator operation amount sensor 26 This corresponds to the operation amount detection means.

In step S12, the target acceleration Atg (m / s ² ) is calculated as follows based on the accelerator operation amount APS and the vehicle speed V (target acceleration calculating means).
First, the target acceleration Atg (m / s ² ) is set by the following linear increase function of the accelerator operation amount APS that is the operation amount x.

Atg = S ・ APS + ACCmin ・ ・ ・ (1)
The intercept ACCmin is a lower limit equilibrium acceleration corresponding to when the accelerator operation amount APS is substantially zero.

Here, the slope S in the linear increase function is set as follows using an exponential decrease function with the vehicle speed V as the base.
S = C · V ^R (C> 0, R <0) (2)
Hereinafter, the operation and effect of setting the target acceleration Atg as described above will be described.

  FIG. 4 shows the relationship between the accelerator operation amount APS and the target acceleration Atg. At the same vehicle speed V, the target acceleration increases with a constant slope S with respect to the increase in the accelerator operation amount APS, but as shown in FIG. The slope S changes nonlinearly every moment according to the change in the vehicle speed V. More specifically, the slope S increases as the vehicle speed V decreases, and the slope S increases as the vehicle speed V increases. The characteristic is that the rate of decrease of the decrease is small. The target acceleration Atg has an upper limit value ACCmax.

The effect will be described with a specific example.
For example, since the vehicle frequently accelerates frequently in a low vehicle speed range such as starting, it is easier to drive when the slope S is relatively high. On the other hand, since the frequency of traveling at a constant speed increases as the vehicle speed increases, driving with a lower slope S is easier. When the vehicle speed further increases and the vehicle travels at a high speed, there is no need to change the slope S. Therefore, as described above, by using the slope S as an exponential decreasing function with the vehicle speed V as the bottom, the driver can drive the vehicle naturally and easily.

  In the equation (2), the lower limit value of the vehicle speed V is set to 1, whereby the slope S is fixed to the upper limit value when the vehicle speed V> 1 as shown in FIG. This is because, in the equation (2) that is an exponential function, if the lower limit of the vehicle speed V that is the bottom is not limited, the vehicle speed becomes zero and S becomes infinite. The slope S may be limited by setting an upper limit directly.

  In manual mode of MT (manual transmission), AT (automatic transmission), CVT (continuously variable transmission), etc., the configuration is such that the coefficient C of the slope S and the exponent part R in the equation (2) are switched by the gear position P. In other words, it is possible to achieve a feeling of acceleration in line with the driver's intention in a wide speed range.

  FIG. 6 shows the relationship between the vehicle speed V and the slope S in the second embodiment in which the coefficient C is switched according to the gear position P (target gear position). The coefficient C is set to a function C (P) that is larger as the gear position P is a lower speed position and smaller as the gear position P is higher.

  In this way, when a multi-stage transmission is provided, it is generally used for acceleration at low-speed gear positions such as 1st and 2nd speeds, and is generally performed at a constant speed at gear positions of 3rd and higher speeds. Therefore, the coefficient C (P) is decreased as the shift is increased, and the slope S is further decreased, so that a more natural feeling is obtained and the driving is facilitated.

  Further, the index R is set to a function R (P) that is smaller as the gear position P is a low speed position (because it is a negative number, the absolute value | R | is larger), and larger as the gear position P is higher (| R | is smaller). However, the same effect can be obtained.

  Furthermore, using these together, the coefficient C (P) is increased as the gear position P is at the low speed position and the index R (P) is decreased, and the coefficient C (P) is increased as the gear position P is at the high speed position. The index R (P) may be set to be small and large.

In addition, the coefficient C and the index R may be switched according to the vehicle speed range and switch operation, and similarly, a feeling of acceleration according to the driver's intention can be realized in a wide speed range.
On the other hand, when the driver does not perform a shift operation as in the normal mode (non-manual mode) of AT cars, if the entire speed range is covered with a single slope S, both the low speed range and the high speed range are compatible. Can be difficult.

  FIG. 7 shows the characteristics of the slope S in the third embodiment that copes with such a case, and a configuration in which the largest one is selected from a plurality of slopes S set by exponential decreasing functions having different coefficients C and exponents R. As a result, the slope S is higher in the low speed range and lower in the high speed range.

The merit of this embodiment for selecting the maximum value is that a continuity at the time of switching is maintained, so that a shock or the like due to a switching step is unlikely to occur.
As a setting example, a characteristic equation with a large coefficient C and a small exponent R as a slope S for low speed (a large absolute value because it is a negative number) and a small coefficient C and a large exponent R as a slope S for high speed ( A characteristic equation (close to zero) may be calculated separately, and the higher sensitivity of the two may be selected and used. Of course, you may select from two or more characteristic formulas.

  In addition, the configuration of selecting the maximum one from the plurality of slopes S of the third embodiment may be applied to the second embodiment, while changing the coefficient C, the index R, etc. according to the gear position, What is necessary is just to set it as the structure which selects the largest thing from several inclination S characteristics from which the coefficient C and the index | exponent R differ in each gear position.

  According to the embodiment shown above, the acceleration feeling can be adjusted in a balanced manner simply by changing the coefficient C and the index R. Therefore, the experimental efficiency during development is high, and even during a short development period. There is also an effect that it is easy to obtain good acceleration performance. Of course, the map value may be calculated and rewritten using the equation according to the present invention while the control logic remains as a conventional map.

  The characteristic of the slope S in the present invention, that is, as a function of the vehicle speed V, which is larger as the vehicle speed is lower and the rate of decrease in the slope S with respect to the increase in the vehicle speed is smaller, The function shown in FIG.

S = C ₀ × 1 / (V + Vo); C ₀ > 0, Vo> 0) (3)
FIG. 8 shows the characteristics of the slope S in the fourth embodiment.
In this method, the setting of the acceleration feeling is slightly troublesome, but a result similar to the calculation result for obtaining the slope S using an exponential function can be obtained. If you do not want to perform exponential calculations due to restrictions such as the performance of the microcomputer you are using, you can achieve similar effects with this method.

  The characteristic equation of the slope S according to the present invention is not limited to those shown in these embodiments, and any other equation that has substantially the same characteristic can be applied.

The system figure of the internal combustion engine for vehicles in an embodiment. The flowchart which shows the main routine of throttle opening control similarly. The flowchart which similarly shows the subroutine which calculates target acceleration. Similarly, the diagram which shows the relationship between accelerator operation amount and target acceleration. The diagram which shows the relationship between the vehicle speed V and the inclination S in 1st Embodiment. The diagram which shows the relationship between the vehicle speed V and the inclination S in 2nd Embodiment. The diagram which shows the relationship between the vehicle speed V and the inclination S in 3rd Embodiment. The diagram which shows the relationship between the vehicle speed V and the inclination S in 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Air cleaner, 3 ... Intake duct, 4 ... Intake collector, 5 ... Intake manifold, 6 ... Intake valve, 7 ... Throttle valve, 8 ... Throttle motor, 9 ... Fuel injection valve, 10 ... Combustion chamber, DESCRIPTION OF SYMBOLS 11 ... Exhaust valve, 12 ... Exhaust manifold, 13 ... Exhaust duct, 14 ... Catalytic converter, 21 ... Engine control unit, 22 ... Air flow meter, 23 ... Air-fuel ratio sensor, 24 ... Rotation speed sensor, 25 ... Accelerator pedal, 26 ... Accelerator operation amount sensor, 27 ... throttle sensor, 28 ... vehicle speed sensor

Claims (13)

An operation amount detection means for detecting an operation amount of an operation member operated by a driver to control driving of the vehicle;
Target acceleration calculation means for calculating a target acceleration Atg of the vehicle by a linear increase function (Atg = S · x + b; S>, b> 0) with the manipulated variable x as a variable;
An accelerator sensitivity calculating means for calculating the slope S of the linear increase function by a function of the vehicle speed V that increases as the vehicle speed decreases and decreases as the vehicle speed increases;
A motion control apparatus for a vehicle, comprising: 2. The accelerator sensitivity calculating means calculates the slope S by an exponential decreasing function (S = C · V ^R ; C> 0, R <0) with a vehicle speed V as a base. Vehicle driving control device.   The driving control apparatus for a vehicle according to claim 2, wherein the accelerator sensitivity calculation means limits an upper limit value of the slope S.   The vehicle operation control device according to claim 3, wherein the upper limit value of the slope S is limited by limiting the bottom vehicle speed V value with a lower limit value.   The vehicle driving according to any one of claims 2 to 4, wherein at least one of the index R and the coefficient C in the index decreasing function is variably set based on a vehicle driving state. Control device.   The vehicle driving control apparatus according to claim 5, wherein the vehicle driving state is the operation amount x.   6. The vehicle operation control device according to claim 5, wherein the vehicle operation state is a gear ratio of a transmission connected to a vehicle-mounted engine.   The vehicle driving control device according to claim 5, wherein the driving state of the vehicle is a vehicle speed V. The driving control apparatus for a vehicle according to claim 1, wherein the accelerator sensitivity calculation means calculates the slope S according to the following equation.
S = C ₀ × 1 / (V + Vo); C ₀ > 0, Vo> 0)   The vehicle operation control apparatus according to any one of claims 1 to 9, wherein an upper limit of the target acceleration Atg is limited by a maximum acceleration obtained by a maximum torque of a vehicle-mounted engine.   11. The vehicle according to claim 1, wherein the slope S in the linear increase function calculates a plurality of candidate values and uses a maximum value among the plurality of candidate values. Operation control device.   The vehicle operation control device according to any one of claims 1 to 11, wherein the operation amount x is an accelerator operation amount APS.   The vehicle driving control device according to any one of claims 1 to 12, wherein the vehicle speed V is substituted by an angular speed of a driving wheel or an engine rotational speed.

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