JPH11268558A - Driving force regulation controlling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving force regulation controlling device for improving the ride feeling of a vehicle, and realizing driving force regulation control excellent in responsiveness in all vehicle speed ranges. SOLUTION: An engine torque command value in accordance with a driving force regulation command value is operated in an engine torque command value operation part 21, and the throttle opening command value of a throttle actuator is operated in a throttle opening operation part 23 from the engine torque command value and an engine speed. Then the lower limit value of the throttle opening command value is made variable in accordance with a vehicle traveling condition, to be operated in a throttle opening lower limit value operation part 25; and a throttle opening is limited in a throttle opening limiter 27 in accordance with the lower limit value. After that, engine torque is operated in an engine torque operation part 29 from the lower limit value of the throttle opening command value and the engine speed, to operate a driving force regulating compensation value in accordance with an engine torque lower limit value is operated in a driving force regulating compenstion value operation part 211. Finally the driving force regulation command value and the driving force regulating compensation value are inputted to operate brake actuator operation quantity in a braking force operating part 213.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance, a vehicle speed,
Alternatively, the present invention relates to a braking / driving force control device for controlling a driving wheel shaft torque of a traveling control device for controlling the braking / driving force.

[0002]

2. Description of the Related Art Conventionally, an inter-vehicle distance to a preceding vehicle is detected,
A braking / driving force control device that controls the vehicle speed or the braking / driving force so that the inter-vehicle distance becomes an appropriate value is known.

[0003] Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 6-234333, "Vehicle running control apparatus", a throttle actuator and a brake actuator are selectively used in order to match a vehicle speed with a target value in order to control an inter-vehicle distance. Have been reported to work. In this example, in order to make the vehicle speed follow the target value, the operation switching from the throttle actuator to the brake actuator is performed when the vehicle speed exceeds the vehicle speed target value, and the switching from the brake actuator to the throttle actuator is performed using the control constant A.
Is performed when the calculated value of the throttle operation amount by the PID vehicle speed control using the control parameter exceeds the calculated value of the brake actuator operation amount by the PID vehicle speed control using the control constant B.

[0004]

However, the conventional braking / driving force control device is configured to switch the operation amounts of two independent controllers for controlling the vehicle speed, that is, a throttle control controller and a brake control controller. At the switching point between the throttle actuator and the brake actuator, a difference occurs in the response characteristics between the two depending on the vehicle speed, so that the braking / driving force becomes discontinuous.
There was a problem that the ride quality deteriorated.

When the vehicle speed is controlled to a low speed range, the engine usually has a large waste time and a delay in the intake system in a low speed range, and a large delay in the engine torque with respect to the throttle opening. It has been difficult to design a vehicle speed control system that can guarantee the same robust control performance over the vehicle speed range.

[0006] The present invention has been made in view of the above,
It is an object of the present invention to provide a braking / driving force control device capable of improving the riding comfort of a vehicle and realizing braking / driving force control with excellent responsiveness in all vehicle speed ranges.

[0007]

According to the first aspect of the present invention,
In order to solve the above-mentioned problem, a braking / driving force control device includes a throttle actuator and a brake actuator, and controls a braking / driving force or a vehicle speed of a vehicle according to a given braking / driving force command value. Engine torque command value calculating means for calculating an engine torque command value according to the following; throttle opening command value calculating means for calculating a throttle opening command value of the throttle actuator from the engine torque command value and the engine speed; Throttle opening lower limit value calculating means for varying the lower limit value of the throttle opening command value according to the running condition of the vehicle, and a throttle for limiting the throttle opening degree according to the lower limit value from the throttle opening lower limit calculating means Opening limit means for calculating an engine torque from a lower limit value of the throttle opening command value and an engine speed; Braking / driving force correction value calculating means for calculating a braking / driving force correction value corresponding to the engine torque lower limit value, and inputting the braking / driving force command value and the braking / driving force correction value, The gist of the present invention is to include a braking force calculating means for calculating an actuator operation amount.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, the throttle opening lower limit calculating means includes a vehicle speed,
The gist is that at least one of the road surface gradient, the inter-vehicle distance, the inter-vehicle relative speed, the fuel cut operation condition, and the throttle opening is used as the traveling condition.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, the throttle opening lower limit calculating means has a gradient estimating means for estimating a gradient of a traveling road surface. The purpose is to output the calculation result of the throttle opening lower limit value so as to guarantee the driving force according to.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, the throttle opening lower limit value calculating means preferentially sets the throttle opening lower limit value to zero when the vehicle speed is equal to or higher than a predetermined value. The point is to output.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, the throttle opening lower limit value calculating means is configured to set the throttle opening lower limit when the fuel cut operation condition is satisfied under conditions other than the throttle opening. The gist is to output the lower limit value as a predetermined non-zero constant.

According to a sixth aspect of the present invention, in order to solve the above-mentioned problem, the throttle opening lower limit value calculating means sets the engine torque command value according to the braking / driving force command value to a negative value equal to or less than a predetermined value. In such a case, the gist is that the throttle opening lower limit is preferentially output as zero.

According to a seventh aspect of the present invention, in order to solve the above-mentioned problem, the throttle opening lower limit calculating means preferentially sets the throttle opening lower limit to a value other than zero when the vehicle speed is equal to or lower than a predetermined value. The point is to output as the value of.

[0014]

According to the present invention, an engine torque command value is calculated in accordance with a braking / driving force command value, and a throttle opening command value of a throttle actuator is calculated from the engine torque command value and the engine speed. Is calculated. Next, the lower limit value of the throttle opening command value is calculated as variable according to the running condition of the vehicle, and the throttle opening is restricted according to the lower limit value. Next, an engine torque is calculated from the lower limit value of the throttle opening command value and the engine speed,
A braking / driving force correction value corresponding to the engine torque lower limit value is calculated. Next, since the braking / driving force command value and the braking / driving force correction value are input and the brake actuator operation amount is calculated, the lower limit value of the throttle opening can be set according to the driving situation. Further, the drive shaft torque can be set to a value corresponding to the command value regardless of a change in the lower limit value of the given throttle opening. As a result, it is possible to improve the riding comfort of the vehicle and realize braking / driving force control with excellent responsiveness in all vehicle speed ranges.

According to the present invention, at least one of the vehicle speed, the road surface gradient, the inter-vehicle distance, the inter-vehicle relative speed, the fuel cut operation condition, and the throttle opening is used as the driving condition. Can be optimally set in accordance with various environmental conditions in which the vehicle is placed.

According to the third aspect of the present invention, the gradient of the traveling road surface is estimated, and the calculation result of the throttle opening lower limit value is output so as to guarantee the driving force according to the gradient estimation result. Therefore, when starting on a slope, the drive shaft torque responsiveness is improved, and the brake is actuated, so that automatic inching can be performed such that it is difficult to retreat on an uphill.

According to the present invention, when the vehicle speed is equal to or higher than the predetermined value, the throttle opening lower limit value is preferentially output as zero, so that the fuel cut operation condition can be reliably set. This can improve fuel economy.

According to the fifth aspect of the present invention, when the fuel cut operation condition is satisfied under conditions other than the throttle opening, the throttle opening lower limit is output as a predetermined non-zero constant. Therefore, the fuel cut operation can be avoided, and the hunting action by the throttle and the brake can be prevented.

According to the present invention, when the engine torque command value corresponding to the braking / driving force command value is a negative value equal to or less than a predetermined value, the throttle opening lower limit is preferentially set to zero. As a result, the fuel cut is activated as before, which can contribute to an improvement in fuel efficiency.

According to the present invention, when the vehicle speed is equal to or lower than the predetermined value, the throttle opening lower limit value is preferentially output as a value other than zero, so that the response of the engine deteriorates. During low-speed running, the drive shaft torque can be controlled only by the brake operation amount, and deterioration of the vehicle speed control performance due to a delay in the response of the drive shaft torque can be prevented.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram for explaining a configuration of a braking / driving force control device according to a first embodiment of the present invention.

In FIG. 1, a vehicle speed control calculation unit 1 calculates a braking / driving force or a braking / driving torque command value for setting the vehicle speed to a value corresponding to the command value. The drive shaft torque control calculator 3, which is a feature of the braking / driving force control device of the present invention, calculates a throttle opening command value and a brake fluid pressure command value for setting the braking / driving torque to a value corresponding to the command value. The throttle opening servo system 5 sets the throttle opening to a value corresponding to the command value. The engine 7 generates a driving force according to the command. The automatic transmission 9 transmits the driving force to a subsequent stage. The differential gear 11 changes the rotation speed by the driving force. The brake 17 generates a braking force. The vehicle body 13 receives the braking / driving force and accelerates / decelerates the moving speed. The brake fluid pressure servo system 15 sets the brake fluid pressure to a value according to the command value.

FIG. 2 is a detailed diagram of the drive shaft torque control system of the braking / driving force control device according to the first and second embodiments of the present invention, that is, the drive shaft torque control calculation unit 3. 2, an engine torque command value calculation unit 21 calculates an engine torque command value from a drive shaft torque command value in consideration of the state of the automatic transmission 9, a gear ratio, and the like. The throttle opening command value calculation unit 23 calculates a first throttle opening command value according to the engine torque command value. The throttle opening lower limit calculator 25 calculates a lower limit of the throttle opening from a running state signal (ie, vehicle speed, gradient, fuel cut, etc.) input from the outside. The throttle opening limiter 27 limits the throttle opening command value according to the throttle opening lower limit value, and calculates a throttle opening command value to be given to the throttle servo system.

The engine torque lower limit calculator 29 calculates the engine torque from the throttle lower limit signal from the throttle opening lower limit calculator and the engine speed. The braking / driving shaft torque correction calculating unit 211 calculates a driving shaft torque generated by the engine torque when the throttle opening is at the lower limit. The braking force calculation unit 213 receives the drive shaft torque command value and the braking / driving shaft torque correction value, and calculates a brake operation amount to be input to the brake hydraulic servo system.

Next, the operation of the braking / driving force control device according to this embodiment will be described. FIG. 3 is a block diagram for explaining a configuration of functional elements of a vehicle speed control system in the braking / driving force control device according to the first embodiment of the present invention. The vehicle speed control system is a system for describing the braking / driving force control device according to the first embodiment of the present invention from the viewpoint of vehicle speed control, and includes, as functional elements, a vehicle speed control unit 1 and a drive shaft torque described later. And a control system.

In FIG. 3, a vehicle speed control unit 1 shows details of a vehicle speed control calculation unit 1, and makes the actual vehicle speed coincide with a vehicle speed command value from an inter-vehicle distance control unit described later. However, the transmission delay of the drive shaft torque control system described later can be ignored. The running resistance estimating unit 31 calculates the drive shaft torque command value T
_{From the wr} and the vehicle speed V _sp , the drive shaft torque conversion value T _dh of the running resistance is estimated using the following equation (1), and the effects such as the gradient, the air resistance, and the rolling resistance are eliminated by feedback.

[0027]

(Equation 1) However, in (1), M _v is the vehicle weight, R _w is the tire radius, H (s) steady-state gain = 1 of the low-pass filter). Assuming that disturbance to the control system is eliminated by the running resistance estimation, the transfer characteristic from the vehicle speed command value to the actual vehicle speed is represented by the following equation (2).

[0028]

(Equation 2) From equation (2), by setting the constant K _SP to an appropriate value,
The response characteristics of the vehicle speed control system can be made to match desired response characteristics.

Next, the operation of the drive shaft torque control system, which is a feature of the braking / driving force control device of the present invention, will be described. The drive shaft torque control system includes a drive shaft torque control calculation unit 3 as a component, and calculates a throttle opening command value and a brake fluid pressure command value for realizing the drive shaft torque calculated by the vehicle speed control unit 1. I do.

Next, the braking / driving force control device of the present invention will be described with all its functions as a braking / driving system, and the operation of the braking / driving system will be disassembled into functional elements. FIG. 4 is a block diagram for explaining functional elements of the braking / driving system in the braking / driving force control device according to the first embodiment of the present invention.

The torque gain of the torque converter is represented by R _t ,
The transmission gear ratio is R _at , the differential gear ratio is R _def , the engine inertia is J _e , and the engine speed is N.
_{Assuming e} , the relationship between the drive shaft torque _Tw and the engine torque _Te is expressed by the following equation (3).

[0032]

(Equation 3) Thus, the drive shaft torque command value T _wr, to calculate the engine torque command value T _er (4) below, the throttle opening to generate the engine torque command value T _er theta
_l is calculated using the engine map, and the throttle opening θ _l
Is equal to or greater than the lower limit value θ _L.

[0033]

(Equation 4) Throttle opening theta _l is equal to or lower limit theta _L or more, can be realized torque of the drive shaft torque command value as only the engine torque without braking. Throttle opening theta _l is, if less than the lower limit value theta _L, the throttle opening and the lower limit value theta _L, this time to match the command value driving shaft torque in consideration of the drive shaft torque output by the engine The brake operation amount of is calculated.

As described above, the engine torque command value T
_er and the distribution control law of the brake torque command value _Tbr are given in the description including the following equations (5) to (9). First, when the throttle opening command value θ _l ≧ θ _L , the following (5),
Equation (6) holds.

[0035]

(Equation 5)

(Equation 6) Therefore, with respect to the wheel torque command value _Twr , the following (7)
What is necessary is just to generate the engine torque shown in a formula.

[0036]

(Equation 7) Also, from equation (5), the brake operation amount is zero. Then, when the throttle opening command value θ _l <θ _L, the throttle opening degree of the engine torque when the theta _L and T _elim,
The expression (3) is replaced by the following expression (8).

[0037]

(Equation 8) Therefore, with respect to the wheel torque command value _Twr , the following (9)
What is necessary is just to generate the type of brake torque.

(Equation 9) The brake cylinder area is A _b , the rotor effective radius is R _b ,
When the pad friction coefficient is mu _b, to the brake torque command value T _br, liquid pressure command value is a brake operation amount is below (10).

[0038]

(Equation 10) Here, the above operation will be described with reference to FIG. First,
The engine torque command value calculation unit 21 receives the drive shaft torque command value _Tr , the transmission gear ratio, and the torque ratio Rt of the torque converter, and calculates the engine torque command value _Ter using Expression (4). In the throttle opening computing unit 23, the engine torque command value T _er and the engine speed N _e, the engine torque command value T by using the engine map such as shown in FIG. 5
It calculates a throttle opening command value theta _l for outputting the _er. The throttle opening limiter 27 calculates the throttle opening lower limit θ calculated by the throttle opening lower limit calculating unit 25.
Comparing the _L and theta _l, a theta _l larger than the throttle opening command value theta _l is theta _L and the throttle opening command value theta _r, when throttle opening command value theta _l is less than theta _L is a theta _L the throttle opening command value theta _r.

Next, the engine torque lower limit calculator 29
Inputs the engine speed and the throttle opening lower limit θ _L , and calculates the engine torque T _elim using a table map of the engine torque as shown in FIG. 6. The braking / driving force correction value calculation unit 211 calculates the second term on the right side of the equation (9). In the braking force computing unit 213, (9) performs addition of the right side of the equation the first term and the second term calculates the brake fluid pressure command value P _br based on equation (10).

FIGS. 7 and 8 show computer simulation results for comparing and showing the effect of the drive shaft torque control of the braking / driving force control device according to the present embodiment under two different conditions. FIG. 7 shows a computer simulation result when the lower limit of the throttle opening is zero, and FIG. 8 shows a computer simulation result when the lower limit of the throttle opening is not zero. In FIG. 8, the operation amount of the brake increases because the throttle opening does not become zero. From these results, in both cases, a drive shaft torque almost matching the command value was obtained, and almost no torque step was observed when switching between the throttle and the brake. Further, even if the lower limit value of the throttle opening is changed, since the brake operation amount is calculated in consideration of the engine torque at that time, it can be seen that the drive shaft torque matches the command value.

However, in general, when the engine speed is low, the responsiveness is worse than when the engine speed is high.
The stability margin of the vehicle speed control system at low speed traveling is reduced as compared with that at high speed traveling. Further, it is difficult to maintain the same vehicle speed control performance over the entire speed range due to the existence of non-linear elements such as a torque converter and a gear transmission efficiency from the engine to the drive wheels. On the other hand, since the brake acts directly on the wheels, the delay is small, and the dynamic characteristics change is small as compared with the drive system including the engine and the transmission. In general, the brake fluid pressure control system can relatively easily respond at high speed as compared with the response of a drive system including an engine and a transmission.

Therefore, in the present invention, the vehicle speed control performance is improved by setting the throttle opening lower limit to a value other than zero at a low speed and increasing the state in which the driving force is controlled only by the brake operation.

For example, in FIG. 2, the vehicle speed V _sp is input to the throttle opening lower limit calculating unit 25, and the lower limit θ is gradually increased from 15 km / h to 10 km / h using the following equation (11).
Increase _L to approach θ _LMT .

[Equation 11] However, (11) the formula, when the V _sp ≧ 15km / h, when the _{V sp L = 15km / h V} sp ≦ 10km / h, V sp L = 10km / h lO <V sp <15km / h In this case, V _sp L = V _sp .

FIGS. 9 and 10 show computer simulation results for comparing the effect of the drive shaft torque control at low speed of the braking / driving force control device according to this embodiment under two different conditions. Show. The simulation results shown in FIGS. 9 and 10 show that the vehicle speed command value is 10 km / h and the time 2
The operation was performed assuming a situation where the vehicle runs on an uphill with a gradient of 6% between 0 and 30 (s). FIG. 9 shows the case where the throttle opening lower limit is set to zero, and FIG. 10 shows the case where the throttle opening lower limit is set to 2 (deg). Both had the same vehicle speed control gain. From this result, it can be seen that, in FIG. 10, the response of the drive shaft torque to the command value is improved as compared with FIG. 9, so that the vehicle speed error is kept small and the vehicle speed control performance is improved.

(Second Embodiment) FIG. 11 is a block diagram for explaining a configuration of a braking / driving force control device according to a second embodiment of the present invention. In the present embodiment, a case will be described in which the braking / driving force control device of the present invention is applied to inter-vehicle distance control (inching) for starting and stopping. When starting up a hill on an uphill slope resistance greater than the creep force, if the time from when the driver releases the brakes to when the accelerator is depressed is slow, the vehicle retreats. A similar phenomenon can occur in automatic inching. In order to avoid this phenomenon, the gradient resistance converted to the drive shaft torque is always estimated, the throttle opening for generating this estimated value is calculated, and this opening is used as the throttle opening lower limit.

In FIG. 11, an inter-vehicle distance command value calculation unit 1
11 generates, for example, an appropriate inter-vehicle distance command value according to the vehicle speed. The inter-vehicle distance measuring unit 112 is an inter-vehicle distance measuring unit, and measures the inter-vehicle distance with a radar or the like. The inter-vehicle distance control calculation unit 113 calculates a vehicle speed command value for setting the measured inter-vehicle distance to a value corresponding to the command value. Slope estimation calculation unit 11
5, a gradient is estimated from a vehicle speed, a drive shaft torque command value, and a vehicle specification value, and the estimated value is used as a throttle opening lower limit calculation unit 25 (FIG. 2) which is a component of the drive shaft torque control calculation unit 3.
). The vehicle stop determining unit 117 determines that the vehicle is stopped based on the vehicle speed command value, the vehicle speed measured value, and the inter-vehicle distance error, and sets the throttle opening to zero when the vehicle is stopped to generate a predetermined brake fluid pressure. Are input to the throttle opening servo system 5 and the brake hydraulic servo system 15. The other components are the same as the components of the first embodiment, and will not be described.

Next, the operation of the braking / driving force control device according to this embodiment will be described. First, the inter-vehicle distance control calculation unit 113 will be described. The inter-vehicle distance control calculation unit 113 calculates the inter-vehicle distance L measured by a radar or the like as an inter-vehicle distance command value L.
Calculate the vehicle speed command value to match _r . The inter-vehicle distance command value is represented by T as the inter-vehicle time to be secured and V _sp
Assuming that the inter-vehicle distance command value at the time of stop is L _off , it can be derived by the following equation (12).

[0048]

(Equation 12) FIG. 12 is a block diagram for explaining a configuration of an inter-vehicle distance control system in the braking / driving force control device according to the second embodiment of the present invention. The inter-vehicle distance control system is a system for describing the braking / driving force control device according to the second embodiment of the present invention in terms of the inter-vehicle distance, and includes an inter-vehicle distance control unit 113 as a component.

In FIG. 12, an inter-vehicle distance control unit 113
Shows the details of the inter-vehicle distance control calculation unit 113. Now, the vehicle speed control system has a primary delay of the response of the actual vehicle speed V _sp to the vehicle speed command value V _spr of the time constant τ _V (= 1 / ω). It can be approximated by a system.

The transfer characteristic of the inter-vehicle distance command value L _r at this time to actual headway distance L _v is a following equation (13).

(Equation 13) (13) from the equation, the inter-vehicle distance control system, by setting the K _V and K _L to a suitable value, it is possible to match the following response to the desired response characteristics.

Next, the gradient estimation calculating section 115 will be described. The gradient can be calculated in the same manner as in equation (1). However, since the equation (1) is estimated in a form including all the air resistance, rolling resistance, and the like, it is necessary to subtract these resistances from the estimated value. Air resistance F _a is (14) below, rolling resistance F _r is calculated by (15) below.

[0052]

[Equation 14]

(Equation 15) However, mu _a coefficient of air resistance, the S _v frontal projected area, the mu _r rolling resistance coefficient, M _v is the vehicle weight, g is the gravitational acceleration.
Thus, the drive shaft torque corresponding value T _i of the gradient resistance becomes below (16).

[0053]

(Equation 16) The running resistance estimation operation, the vehicle is stopped, the vehicle stop determination part 117 to be described next is operation, because not be accurately running resistance, is stopped, the gradient a mean value of T _i immediately before stop resistance is used as a drive shaft torque corresponding value T _i.

Next, the vehicle stop judging section 117 will be described. The vehicle stop determination unit 117 determines that the vehicle has stopped, sets the throttle opening to zero, and provides a command signal for generating a predetermined brake fluid pressure to the throttle opening servo system and the brake fluid pressure servo system. In the present embodiment, it is determined that the vehicle is stopped when all the conditions shown in the following equations (17), (18), and (19) are satisfied.

[0055]

[Equation 17]

(Equation 18)

[Equation 19] Here, V1, V2, and L1 are constants.

Next, the operation of the throttle opening lower limit calculation unit 25 which is a component of the drive shaft torque control calculation unit 3 in the present embodiment will be described. Throttle opening lower limit calculating section 25 inputs the drive shaft torque corresponding value T _i of the gradient resistance from the gradient estimation calculation section 115 calculates the throttle opening theta _L so as to output a drive shaft torque corresponding value T _i .

Now, it is assumed that the vehicle is stopped on the uphill by controlling the throttle. In this case we assume that the engine speed fluctuations are small, ignoring this, engine torque T _ei for outputting a drive shaft torque corresponding value T _i can be calculated by (20) below.

[0058]

(Equation 20) Next, a throttle opening for outputting the engine torque _Tei is obtained with reference to an engine map shown in FIG. 5, and this is set as a lower limit value _θLMT . Further, in the present embodiment,
In order to set the throttle opening lower limit at a predetermined speed or less, similarly to the first embodiment, the lower limit θ _L is gradually increased from 10 km / h to 5 km / h using the following equation (21).
To approach θ _LMT .

[0059]

(Equation 21) However, (21) the formula, when the _{V sp ≧ 10km / h, V} sp L = 10Km / h V when the _{sp ≦ 5km / h, V sp} L = 5km / h 5 <V sp <10km / h , V _sp L = V _sp . The operation of the other components is the same as that of the first embodiment, and therefore will not be described.

FIGS. 13 and 14 show computer simulation results for comparing and showing the effects of the braking / driving force control device according to the present embodiment. FIG. 13 shows a case where the throttle opening lower limit is fixed to zero, and FIG. 14 shows a case where the present embodiment is applied. In FIG. 13, when the vehicle starts from a stop, the vehicle speed is in a negative direction, and the vehicle moves backward for a moment and then advances. At this time, the vehicle speed control error is large. On the other hand, FIG.
Then, as described above, in addition to the improvement of the torque response, the braking torque by the brake becomes a positive torque when the vehicle retreats, and it becomes more difficult to retreat, so that the vehicle speed control error becomes relatively small.

In FIG. 14, the reason why the brake fluid pressure is a predetermined value from the latter half of the time 10 (s) to the first half of the 30 (s) is that the vehicle stop judging unit 117 is operating.

(Third Embodiment) Conventionally, when the throttle opening is fully closed when the engine speed is higher than a certain level, fuel to the engine is cut off to improve fuel efficiency (hereinafter referred to as "fuel"). Devices called "cuts" are known. When the vehicle is equipped with a fuel-cut device and a constant-speed traveling device or an inter-vehicle distance control device, the throttle valve is returned to near full closure when traveling downhill, when decelerating to follow the preceding vehicle, etc. There is. In such a case, the driving torque is rapidly reduced in a step-like manner by the fuel cut, and the vehicle speed falls below the target vehicle speed. Therefore, the vehicle speed control device controls the throttle valve to open. Then, the fuel is supplied again, the driving torque increases stepwise, and the vehicle speed sharply increases, so that the throttle valve is controlled to be closed, and the vehicle speed sharply decreases again by fuel cut. As described above, when the fuel cut is repeatedly turned on and off, the engine torque fluctuates, and the ride quality is deteriorated. In order to avoid this phenomenon, in the present embodiment, when a condition other than the throttle opening becomes a condition for performing fuel cut,
The throttle opening lower limit is set to a small value other than zero to prevent fuel cut. Next, when the drive shaft torque command value is equal to or greater than the braking torque due to the fuel cut, the fuel cut is activated, the brake is controlled, and the torque step due to the fuel cut operation is canceled.

FIG. 15 is a block diagram for explaining the configuration of the functional elements of the braking / driving force control device according to the third embodiment of the present invention. FIG. 16 is a detailed diagram of the drive shaft torque control calculation unit 3. FIG. 17 is a table map for obtaining the engine torque of the braking / driving force control device according to the third embodiment of the present invention when the fuel cut operation is performed and when the fuel cut operation is not performed. FIG. 18 shows a third embodiment of the present invention.
And a switching unit for switching a table map for obtaining an engine torque corresponding to each of a fuel cut operation and a non-operation of the braking / driving force control device according to the embodiment.

In FIGS. 15 and 16, the fuel cut establishment determining section 153 determines whether the conditions other than the throttle opening are the conditions for performing the fuel cut.
A signal is passed to the throttle opening lower limit calculation unit 25. The fuel cut on / off determining unit 151 compares the drive torque command value with the drive shaft torque by fuel cut to determine whether the fuel cut operation is performed or not, and passes a signal to the throttle opening lower limit calculation unit 25. The engine torque lower limit calculation unit 169 includes an engine map at the time of fuel cut.
As shown in FIG. 8, the operation of the switch switching unit 81 causes the engine torque to change in a step-like manner.
According to the calculation rule shown in FIG. 9, the signal from the fuel cut establishment determining section 153 and the throttle opening lower limit signal are input, and when the fuel cut condition is satisfied, the engine map is switched to obtain the engine output torque. The other components are the same as the components of the first embodiment, and will not be described.

Next, the operation of the braking / driving force control device according to this embodiment will be described. When the fuel cut is activated,
As shown in FIG. 17, since the engine torque decreases stepwise, it becomes impossible to output the drive shaft torque between the time of the fuel cut operation and the time of the non-operation. Therefore, until the drive shaft torque command value T _wr exceeding the driving shaft torque T _{wf c} by fuel cut is input, and deactivates the fuel cut by setting the throttle opening degree lower limit value other than zero to a small value α Then, a braking torque is generated by the brake. When a drive shaft torque command value equal to or greater than _Twfc is input, the throttle opening lower limit is set to zero, fuel cut is activated, and at the same time, the brake fluid pressure corresponding to the drive shaft torque due to fuel cut is reduced. The operation of each component will be described below.

The fuel cut establishment determining section 153 determines whether a condition other than the throttle opening is a fuel cut operation condition. FCA = 1 if fuel cut operating condition, otherwise FCA = 0
And Fuel cut-off determination section 151 calculates the drive shaft torque T _wfc when it is fuel cut (22) below, is compared with the drive shaft torque command value T _wr.

[0067]

(Equation 22) In the equation (22), _Tefc is the engine torque during the fuel cut operation, and is calculated using a map as shown in FIG.

Whether to activate the fuel cut is determined by
For example, it is determined by the following logic.

[0069] <When 1.5 T _wfc, fuel cut operation (FCB = 1) becomes, T _wr> T _wr 1.2 when T _wfc, the fuel cut inoperative (FCB = 0).

The throttle lower limit calculating unit 25 receives the signal FCA from the fuel cut establishment determining unit 153 and the signal FCB from the fuel cut on / off determining unit 151, and according to the calculation rule shown in FIG. Determine the value.

Engine torque lower limit calculating section 169 determines whether signal FCA from fuel cut establishment determining section 153 is 1 or not.
When the throttle opening lower limit signal θ _L is zero, it is determined that the fuel cut operation is being performed, and the engine torque is obtained by referring to the engine map at the time of the fuel cut operation.
In other cases, the engine torque is determined with reference to the engine map when the fuel cut is not operated. The operation of the other components is the same as that of the first embodiment, and therefore will not be described.

FIGS. 20 and 21 show computer simulation results for comparing and showing the effects of the braking / driving force control device according to the present embodiment. In the simulation, it is assumed that the gradient changes as shown in both figures while traveling downhill at about 80 km / h. The result shown in FIG. 20 is a case where no countermeasures are taken regarding the fuel cut surge (the lower limit of the throttle opening is set to zero, and the engine torque lower limit calculation unit refers to the engine map when the fuel cut is not operated). The result shown in FIG. 20 is a case where the present embodiment is applied.

From the above results, it can be seen from FIG. 1 that the hunting of the throttle and the brake due to the fuel cut occurs when the throttle opening becomes close to zero for the vehicle speed to match the command value, and the riding comfort deteriorates. You can see that there is. Further, since no reference to the engine map of the fuel cut operation, the command value T _{w r} and the drive shaft torque T _w
Is relatively large.

On the other hand, in FIG. 2, the conditions under which the fuel cut operates are determined, and the lower limit is set for the throttle opening, so that the fuel cut does not operate. Further, when the drive shaft torque command value further increases in the negative direction, the lower limit of the throttle opening is set to zero, the fuel cut is activated, and the brake fluid level is changed in order to cancel the torque step caused by the fuel cut. . As a result, hunting can be prevented, and the drive shaft torque T _w is consistent with the command value T _wr.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a configuration of functional elements of a braking / driving force control device according to a first embodiment of the present invention.

FIG. 2 is a detailed diagram of a drive shaft torque control system of the braking / driving force control device according to the first and second embodiments of the present invention.

FIG. 3 is a block diagram for explaining a configuration of a functional element of a vehicle speed control system in the braking / driving force control device according to the first embodiment of the present invention.

FIG. 4 is a block diagram for explaining functional elements of a braking / driving system in the braking / driving force control device according to the first embodiment of the present invention.

FIG. 5 shows an engine torque command value _Ter and an engine speed N
and a _e, an engine map for determining the throttle opening command value theta _l.

FIG. 6 is a table map for _obtaining an engine torque T _elim from an engine speed and a throttle opening lower limit value θ _L.

FIG. 7 is a computer simulation result showing the effect of drive shaft torque control when the lower limit of the throttle opening of the braking / driving force control device according to the first embodiment of the present invention is zero.

FIG. 8 is a computer simulation result showing the effect of drive shaft torque control when the lower limit of the throttle opening of the braking / driving force control device according to the first embodiment of the present invention is not zero.

FIG. 9 shows a vehicle speed command value of 10 km / h and a time of 20 to 30 (s) in order to show the effect of the drive shaft torque control of the braking / driving force control device according to the first embodiment of the present invention during low-speed running. 7 is a computer simulation result in a case where a scene running uphill with a gradient of 6% is assumed and the throttle opening lower limit is set to zero.

FIG. 10 shows a vehicle speed command value of 10 km / h and a time of 20 to 30 (s) in order to show the effect of the drive shaft torque control of the braking / driving force control device according to the first embodiment of the present invention during low-speed running.
Is a computer simulation result assuming a situation in which the vehicle travels on an uphill with a gradient of 6% during this time and the lower limit of the throttle opening is set to 2 (deg).

FIG. 11 is a block diagram illustrating a configuration of functional elements of a braking / driving force control device according to a second embodiment of the present invention.

FIG. 12 is a block diagram for explaining a configuration of functional elements of an inter-vehicle distance control system in a braking / driving force control device according to a second embodiment of the present invention.

FIG. 13 is a computer simulation result showing an effect when the throttle opening lower limit is fixed to zero as in the related art in the braking / driving force control device according to the second embodiment of the present invention.

FIG. 14 is a computer simulation result showing an effect of the braking / driving force control device according to the second embodiment of the present invention.

FIG. 15 is a block diagram for explaining a configuration of functional elements of a braking / driving force control device according to a third embodiment of the present invention.

FIG. 16 is a detailed view of a drive shaft torque control system of a braking / driving force control device according to a third embodiment of the present invention.

FIG. 17 is a table map for obtaining an engine torque for each of a fuel cut operation and a non-operation of the braking / driving force control device according to the third embodiment of the present invention.

FIG. 18 is a switching unit for switching a table map for obtaining an engine torque corresponding to each of a fuel cut operation and a non-operation of the braking / driving force control device according to the third embodiment of the present invention.

FIG. 19 is a diagram illustrating a signal FCA from a fuel cut establishment determining unit 153 and a fuel cut on / off determining unit 1 in the braking / driving force control device according to the third embodiment of the present invention.
FIG. 6 is a diagram showing an operation rule for determining a throttle opening lower limit value from a signal FCB from the controller 51;

FIG. 20 is a computer simulation result showing an effect when a countermeasure for a fuel cut surge is not taken in the braking / driving force control device according to the third embodiment of the present invention as in the related art.

FIG. 21 is a computer simulation result showing an effect of the braking / driving force control device according to the third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 vehicle speed control calculation unit 3 braking / driving torque control calculation unit 5 throttle opening servo system 7 engine 9 automatic transmission 11 differential gear 13 vehicle body 15 brake hydraulic servo system 17 brake 21 drive shaft torque command value calculation unit 23 throttle opening command value Calculation unit 25 Throttle opening lower limit calculation unit 27 Throttle opening limiter 29 Engine torque lower limit calculation unit 31 Running resistance estimation unit 111 Inter-vehicle distance command value calculation unit 112 Inter-vehicle distance measurement unit 113 Vehicular distance control calculation unit 115 Slope estimation calculation unit 117 Vehicle stop determination unit 151 Fuel cut on / off determination unit 153 Fuel cut establishment determination unit 169 Engine torque calculation unit 211 Strain / drive shaft torque correction calculation unit 213 Braking force calculation unit

Claims (7)

[Claims] 1. A braking / driving force control device including a throttle actuator and a brake actuator for controlling a braking / driving force or a vehicle speed of a vehicle according to a given braking / driving force command value, wherein the braking / driving force control device is responsive to the braking / driving force command value. An engine torque command value calculating means for calculating the engine torque command value, a throttle opening command value calculating means for calculating a throttle opening command value of the throttle actuator from the engine torque command value and the engine speed, Throttle opening lower limit value calculating means for varying the lower limit value of the degree command value according to the running condition of the vehicle, and a throttle opening degree for limiting the throttle opening degree according to the lower limit value from the throttle opening lower limit calculating means. Limiting means; an engine torque lower limit for calculating an engine torque from the lower limit value of the throttle opening command value and the engine speed. Computing means; braking / driving force correction value computing means for computing a braking / driving force correction value according to the engine torque lower limit value; and inputting the braking / driving force command value and the braking / driving force correction value, And braking force calculating means for calculating the braking force. 2. The throttle opening lower limit calculating means uses at least one of a vehicle speed, a road surface gradient, an inter-vehicle distance, an inter-vehicle relative speed, a fuel cut operation condition, and a throttle opening as a driving situation. The braking / driving force control device according to claim 1. 3. The throttle opening lower limit calculating means includes a gradient estimating means for estimating a gradient of a traveling road surface, and the throttle opening degree lowering means calculates a driving force according to a gradient estimation result of the gradient estimating means. The braking / driving force control device according to claim 1 or 2, wherein a calculation result of the degree lower limit value is output. 4. The throttle opening lower limit calculating means according to claim 3, wherein the throttle opening lower limit is preferentially output as zero when the vehicle speed is equal to or higher than a predetermined value. Driving force control device. 5. The throttle opening lower limit calculating means outputs the throttle opening lower limit as a predetermined non-zero constant when a fuel cut operation condition is satisfied under conditions other than the throttle opening. The braking / driving force control device according to claim 4, characterized in that: 6. The throttle opening lower limit value calculating means, when the engine torque command value corresponding to the braking / driving force command value is a negative value equal to or less than a predetermined value, gives priority to the throttle opening lower limit value. 6. The braking / driving force control device according to claim 5, wherein the braking / driving force is output as zero. 7. The throttle opening lower limit value calculating means outputs the throttle opening lower limit value as a value other than zero preferentially when the vehicle speed is equal to or less than a predetermined value. The braking / driving force control device according to the above.