JPH1035322A - Vehicle speed control device for vehicles - Google Patents

Abstract

(57) [Summary] [Problem] To suppress overshoot of vehicle speed at the end of acceleration or at the end of uphill. SOLUTION: An engine non-linear steady-state characteristic map is set so that a target throttle opening degree becomes constant when a target engine torque exceeds a predetermined value. Then, a target engine torque is calculated based on a deviation between the actual vehicle speed and the target vehicle speed, and a target throttle opening is calculated from the target engine torque by using the engine non-linear steady-state characteristic map. The throttle valve is controlled so that As a result, the throttle can be quickly closed at the end of acceleration or at the end of uphill traveling, and overshoot of the vehicle speed can be sufficiently suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed control device for controlling the running speed of a vehicle to a target value.

[0002]

2. Description of the Related Art A target engine torque is calculated based on a deviation between a target vehicle speed and an actual vehicle speed, and a throttle opening command value is tabulated based on the target engine torque and the engine rotation speed from a previously measured engine non-linear steady-state characteristic map. 2. Description of the Related Art There is known a vehicle speed control device for a vehicle that calculates and controls an actual throttle opening to match an opening command value (for example, see Japanese Patent Application Laid-Open No. 63-144797).

[0003]

However, in the above-described conventional vehicle speed control apparatus, the rate of change of the throttle opening with respect to the torque change is large near the maximum torque due to the non-linear characteristics of the engine, so that a large output torque is required. When the vehicle is accelerating or traveling on an uphill road, the throttle is greatly opened in response to a slight increase in the torque command value. Therefore, there is a problem that the return of the throttle is delayed at the end of acceleration or at the end of uphill, and an overshoot of the vehicle speed occurs.

An object of the present invention is to provide a vehicle speed control device for a vehicle that suppresses overshooting of the vehicle speed at the end of acceleration or at the end of uphill.

[0005]

[Means for Solving the Problems]

(1) According to the first aspect of the invention, the engine non-linear steady-state characteristic map is set so that the target throttle opening becomes constant when the target engine torque exceeds a predetermined value. Then, a target engine torque is calculated based on a deviation between the actual vehicle speed and the target vehicle speed, and a target throttle opening is calculated from the target engine torque by using the engine non-linear steady-state characteristic map. The throttle valve is controlled so that (2) The vehicle speed control device for a vehicle according to claim 2 changes the predetermined value according to the state of the vehicle. (3) The vehicle speed control device for a vehicle according to claim 3 estimates the acceleration of the vehicle, and sets the target engine torque at the time when the estimated acceleration value falls below the threshold value 1 during the constant speed traveling control to the predetermined value. It is something to do. (4) The vehicle speed control device for a vehicle according to claim 4 estimates the acceleration of the vehicle, and sets the target engine torque at the time when the estimated acceleration value drops by 2 or more from the target acceleration during the acceleration control to the predetermined value. It is something to set. (5) The vehicle speed control device for a vehicle according to claim 5, wherein the target engine torque at the time when the actual vehicle speed becomes lower than the target vehicle speed by the threshold value 3 or more during the constant speed traveling control is set to the predetermined value. It is. (6) The vehicle speed control device for a vehicle according to claim 6, wherein the target engine torque at the time when the actual vehicle speed falls below the target vehicle speed by the threshold value 4 or more during the acceleration control is set to the predetermined value. .

[0006]

(1) According to the first aspect of the invention, the throttle can be quickly closed at the end of acceleration or at the end of uphill traveling, and the overshoot of the vehicle speed can be sufficiently suppressed. (2) According to the second aspect of the invention, variations in the characteristics of the engine and the vehicle are automatically corrected. (3) According to the third aspect of the invention, for example, when the vehicle approaches a steep uphill while traveling at a constant speed on a flat road, the target engine torque increases and the throttle is opened as the actual vehicle speed falls below the target vehicle speed. Control this way. However, even if the target engine torque exceeds the value at the time when the estimated acceleration value falls below the threshold value 1, the throttle opening is kept constant and the throttle is not opened any more. When a flat road or a downhill is reached, the throttle can be quickly closed, and the overshoot of the vehicle speed can be sufficiently suppressed. (4) According to the invention of claim 4, for example, when the vehicle is accelerated from the constant speed traveling, as the actual vehicle speed becomes lower than the target vehicle speed, the target engine torque is increased to control to open the throttle. However, even if the target engine torque exceeds the value at the time when the estimated acceleration value falls below the target acceleration by the threshold value 2 or more, the throttle opening is kept constant and the throttle is not opened any more. Upon completion, the throttle can be closed quickly, and overshoot of the vehicle speed can be sufficiently suppressed. (5) According to the fifth aspect of the invention, for example, when the vehicle approaches a steep uphill while traveling at a constant speed on a flat road, as the actual vehicle speed falls below the target vehicle speed, the target engine torque increases and the throttle is opened. Control this way. However, even if the target engine torque exceeds the value at the time when the actual vehicle speed has decreased by more than the threshold value 3 from the target vehicle speed, the throttle opening is kept constant and the throttle is not opened any more. Thus, when the vehicle becomes a flat road or a downhill, the throttle can be quickly closed, and the overshoot of the vehicle speed can be sufficiently suppressed. (6) According to the invention of claim 6, for example, when accelerating from a constant speed traveling, as the actual vehicle speed decreases from the target vehicle speed,
The target engine torque is increased to control opening the throttle. However, even if the target engine torque exceeds the value at the time when the actual vehicle speed falls below the target vehicle speed by the threshold value 4 or more,
Since the throttle opening is kept constant and the throttle is not opened any more, the throttle can be quickly closed when the acceleration is completed, and the overshoot of the vehicle speed can be sufficiently suppressed.

[0007]

FIG. 1 is a diagram showing a configuration of an embodiment. In the negative pressure type throttle actuator 1, a diaphragm 3 is installed in a housing 2, and the diaphragm 3 moves according to a negative pressure in a negative pressure chamber 4. The diaphragm 3 is constantly urged to the left in the figure by the spring 5,
It is connected to a throttle valve 7 in a throttle chamber 6 via a throttle wire (not shown). When the negative pressure in the negative pressure chamber 4 decreases, the diaphragm 3 moves rightward in the drawing by the urging force of the spring 5, and the throttle valve 7 is driven in the closing direction. Conversely, when the negative pressure in the negative pressure chamber 4 increases,
The diaphragm 3 moves to the left in the drawing due to the urging force of the spring 5, and the throttle valve 7 is driven in the opening direction.

The negative pressure in the negative pressure chamber 4 of the throttle actuator 1 is controlled by a vacuum valve 8, a vent valve 10, and a safety valve 12. The vacuum valve 8 is connected to an intake manifold (not shown) of the engine, and stores a negative pressure in the negative pressure chamber 4. The vacuum valve 8 is opened and closed by a solenoid 9. The vent valve 10 is opened and closed by a solenoid 11 to release the negative pressure in the negative pressure chamber 4 to atmospheric pressure. The safety valve 12 is a valve used for fail-safe operation, is opened and closed by a solenoid 13, and releases the negative pressure of the negative pressure chamber 4 to atmospheric pressure.

The controller 14 includes a microcomputer 15, a memory 16, and the like. The controller 14 drives and controls the vacuum valve solenoid 9, the vent valve solenoid 11, and the safety valve solenoid 13 to adjust the opening of the throttle valve 7 by the negative pressure type throttle actuator 1. I do.

A throttle sensor 17, a vehicle speed sensor 18, and an engine speed sensor 19 are connected to the controller 14. The throttle sensor 17 is a sensor that detects an opening of the throttle valve 7 (hereinafter, referred to as an actual throttle opening and represented by a symbol Tvo), and outputs a DC voltage corresponding to the actual throttle opening Tvo. Vehicle speed sensor 1
Reference numeral 8 denotes a sensor for detecting a running speed of the vehicle (hereinafter, referred to as an actual vehicle speed or simply as a vehicle speed, which is represented by a symbol Vsp). Output a signal. The controller 14 counts the pulse signal output from the vehicle speed sensor 18 for a predetermined time,
It is converted to the actual vehicle speed Vsp. The engine speed sensor 19 is a sensor for detecting the engine speed Ne, is connected to the crankshaft, and outputs a predetermined number of pulse signals per crankshaft rotation. The controller 14 controls the engine speed sensor 19 for a predetermined time.
Is counted and converted into an engine rotation speed Ne.

The controller 14 also includes a main switch 20, a set switch 21, an accelerate switch 22, a coast switch 23, and a cancel switch 2.
4. The brake switch 25 is connected. The main switch 20 is a switch for operating the vehicle speed control device, and the set switch 21 is a switch for starting the constant speed traveling control and setting the vehicle speed command value (target vehicle speed) Vspr. The accelerator switch 22 is a switch for increasing the vehicle speed command value Vspr in the constant-speed running control, and the coast switch 23 is a switch for reducing the vehicle speed command value Vspr. Further, the cancel switch 24 is a switch for canceling the constant speed traveling control, and the brake switch 25 is a switch that closes when the foot brake is operated.

The controller 14 controls the vacuum valve solenoid 9 based on the actual throttle opening Tvo, the actual vehicle speed Vsp and the engine speed Ne detected by the sensors 17 to 19, and the operation command from the switches 20 to 25.
And the vent valve solenoid 11 is pulsed to adjust the opening of the throttle valve 7.
The WM duty ratio will be described later.

FIG. 2 is a flowchart showing the vehicle speed control of the controller 14. The operation of this embodiment will be described with reference to this flowchart. When the main switch 20 is turned on, the controller 14 executes this control program at predetermined time intervals, for example, every 100 ms. First, in step 1, the actual throttle opening Tvo is calculated by A / D converting the output voltage of the throttle sensor 17. Further, an average vehicle speed is calculated based on the number of input pulses from the vehicle speed sensor 18 for a predetermined time, and is set as an actual vehicle speed Vsp. further,
An average engine speed is calculated based on the number of input pulses for a predetermined time from the engine speed sensor 19, and is set as the engine speed Ne.

In step 2, when the cancel switch 24 is operated or the foot switch operation is detected by the brake switch 25, the cruise control is stopped. That is, in step 17, the constant speed running control flag indicating that the constant speed running control is being performed is cleared, and in the subsequent step 18, the throttle opening command value Tvor stored in the memory 16 is reset to end the vehicle speed control. I do.

On the other hand, when neither the cancel switch 24 nor the foot brake is operated, the process proceeds from step 2 to 3, and the operation of the set switch 21 is confirmed. When the set switch 21 is operated, the cruise control is started. That is, the actual vehicle speed Vsp calculated in the above step is set as the vehicle speed command value Vspr in step 4 and stored in the memory 16. In the following step 5, the constant speed running control flag is set, and the current vehicle speed control process is terminated.

If none of the cancel switch 24, the foot brake, and the set switch 21 are operated, the process proceeds to step 6, where the state of the constant speed running control flag is confirmed. When the constant-speed running control flag is not set, the process proceeds to step 18, where the throttle opening command value Tvor stored in the memory 16 is reset, and the vehicle speed control ends. On the other hand, when the constant speed running control flag is set, the process proceeds to step 7 and thereafter, and the constant speed running control is performed.

In step 7, the accelerator control is performed by executing the subroutine shown in FIG. 3, and in the subsequent step 8, the coast control is executed by executing the subroutine shown in FIG. The acceleration control and the coast control will be described later. Further, in step 9, the subroutine shown in FIG. 5 is executed to calculate a target driving force for matching the two based on the vehicle speed command value Vspr and the actual vehicle speed Vsp. In this embodiment, the target driving force y1 is calculated using a model matching method, which is a known linear control method, and an approximate zeroing method. The calculation of the target driving force will be described later.

In step 10, an opening calculation routine shown in FIG. 6 is executed to calculate a throttle opening command value based on the target driving force y1. The calculation of the throttle opening command value will be described later. In step 11, the PID
The PWM duty ratio of the drive signal of the vacuum valve solenoid 9 and the vent valve solenoid 11 is calculated based on the throttle opening deviation (target opening-actual opening) by a control method. In step 12, the vacuum valve solenoid 9 is operated with the calculated PWM duty ratio.
Alternatively, the drive control of the vent valve solenoid 11 is performed.

Next, the acceleration control will be described with reference to the subroutine of FIG. In step 21, the operation of the accelerate switch 22 is confirmed. If the accelerator switch 22 has not been operated, the process proceeds to step 22, and the state of the accelerator control in progress flag is confirmed. When the accelerated switch 22 is not operated and the accelerated control flag is not set,
It returns to the main routine shown in FIG.

When the accelerator switch 22 is operated, an accelerator control flag is set in step 23, and in a subsequent step 24, the vehicle speed command value Vspr (old) one control cycle before is set to a predetermined value (this embodiment). Then, 0.2k
m / h) to update the vehicle speed command value Vspr. In step 25, the vehicle speed command value Vspr and the actual vehicle speed Vsp
(Vspr-Vsp) exceeds a predetermined value (3 km / h in this embodiment). When the vehicle speed does not exceed the predetermined value, since the actual vehicle speed Vsp sufficiently follows the vehicle speed command value Vspr, the process returns to the main routine. On the other hand, the deviation (Vspr−Vs
If p) exceeds the predetermined value, the actual vehicle speed Vsp is set to a predetermined value (3 km / h in this embodiment) in step 26.
Is set to the vehicle speed command value Vspr.

When the accelerated switch 22 is opened,
When the acceleration control in-progress flag is set, it is determined that the acceleration switch 22 has just been opened, and the process proceeds from step 22 to step 27 to perform processing at the end of the acceleration control. That is, step 2
In step 7, the actual vehicle speed Vsp is set to the vehicle speed command value Vspr. In step 28, the accelerator control flag is cleared.
Then, the process returns to the main routine.

The coast control will be described with reference to the subroutine of FIG. In step 31, the operation of the coast switch 23 is confirmed. If the coast switch 23 has not been operated, the process proceeds to step 32, where the state of the coast control flag is confirmed. When the coast switch 23 is not operated and the coast control in-progress flag is not set, the process returns to the main routine shown in FIG.

When the coast switch 23 is operated, a coast control flag is set in step 33,
In the following step 34, the vehicle speed command value Vspr (ol
The vehicle speed command value Vspr is updated by subtracting a predetermined value (0.2 km / h in this embodiment) from d). In step 35, the deviation (Vs) between the actual vehicle speed Vsp and the vehicle speed command value Vspr
(p-Vspr) exceeds a predetermined value (3 km / h in this embodiment). When the vehicle speed does not exceed the predetermined value, since the actual vehicle speed Vsp sufficiently follows the vehicle speed command value Vspr, the process returns to the main routine. On the other hand, when the deviation (Vsp-Vspr) exceeds the predetermined value, the vehicle speed obtained by subtracting the predetermined value (3 km / h in this embodiment) from the actual vehicle speed Vsp in step 36 is set as the vehicle speed command value Vspr. I do.

If the coast switch 23 is opened and the coast control flag is set, it is determined that the coast switch 23 has just been opened, and the process proceeds from step 32 to 37 to terminate the coast control. Perform That is, in step 37, the actual vehicle speed Vsp is set to the vehicle speed command value Vspr. In step 38, the course control flag is cleared, and the process returns to the main routine.

Next, the calculation of the target driving force will be described with reference to FIG. This calculation is performed using a vehicle speed feedback compensator based on a model matching method and an approximate zeroing method, which are linear control methods, as shown in FIG.

Here, a vehicle model to be controlled incorporated in the vehicle speed feedback compensator will be described. Since the vehicle is modeled with the target driving force as the manipulated variable and the vehicle speed as the control variable, the transient characteristics of relatively responsive engines and torque converters and the non-linear steady-state characteristics of torque converters can be omitted. The behavior of the power train can be represented by a simple nonlinear model shown in FIG. Then, a throttle opening command value such that the actual driving force matches the target driving force is calculated using a previously measured engine steady characteristic map, and the throttle opening is servo-controlled to linearize the engine non-linear steady characteristic. Become Therefore, a vehicle model having the target driving force as input and the vehicle speed as output has an integral characteristic, and the compensator can set the transmission characteristic of this vehicle model to the pulse transmission characteristic P (z ^-1 ).

In FIG. 7, z is a delay operator, and z
Multiplying by ^-1 gives the value one sample cycle earlier. Also, C1
(Z ^-1 ) and C2 (z ^-1 ) are disturbance estimators based on the approximate zeroing method, and suppress the influence of disturbances and modeling errors. Further, C3 (z ^-1 ) is a compensator based on the model matching method, and as shown in FIG. 9, the target vehicle speed Vsp
The response characteristic of the control object when r is input and the actual vehicle speed Vsp is output is made to match the characteristic of the reference model H (z ^-1 ) having a predetermined first-order delay and a dead time element.

It is necessary to consider the dead time, which is the delay of the power train, as the transfer characteristic of the controlled object. This dead time is about 200 msec, which corresponds to a two-sample period in this embodiment. Therefore, the pulse transfer function P
(Z ^-1 ) can be represented by a product of an integral element P1 (z ^-1 ) and a dead time element P2 (z ^-1 ) (= z ^-2 ) shown in the following equation.

(Equation 1) Here, T is a sample period (100 m in this embodiment).
sec), M is the average vehicle weight. At this time, the compensator C1 (z ^-1 ) is represented by the following equation.

(Equation 2) That is, the compensator C1 (z ^-1 ) is a low-pass filter with a time constant Tb. Further, the compensator C2 (z ^-1 ) is C1 /
P1 is represented by the following equation.

(Equation 3) The compensator C2 is obtained by applying a low-pass filter to the inverse system of the vehicle model, and has a driving force affected by disturbance (running resistance) obtained from the actual vehicle speed Vsp, that is, a driving force as shown in FIG. The driving force obtained by subtracting the running resistance from the force can be calculated back. If the reference model H (z ^-1 ) is a first-order low-pass filter with a time constant Ta ignoring the dead time of the control target, the compensator C3 has the following constant.

(Equation 4)

In step 41 of FIG. 5, a portion corresponding to the model matching compensator C3 (z ^-1 ) of FIG. 7 is calculated to obtain a target driving force y4 for accelerating from the actual vehicle speed Vsp to the target vehicle speed Vspr. . Data y (k-
If 1) represents data y (k) one sample cycle earlier,

Y4 (k) = K ・ (Vspr (k) −Vsp (k)) In the following step 42, it corresponds to a part of the robust compensator C2 (z ⁻¹ ) of the disturbance estimator shown in FIG. The calculation of the part is performed, and the driving force y3 affected by disturbance (such as running resistance) is calculated backward based on the actual vehicle speed Vsp.

(Equation 6)

In step 43, the final target driving force y1 is obtained by correcting the target driving force y4 with the estimated running resistance Fr.

Y1 (k) = y4 (k)-(y3 (k) -y2 (k-2)) = y4 (k) + (y2 (k-2) -y3 (k)), Fr = y2 (K-2) -y3 (k) Here, y2 (k-2) is a value of the driving force y2 (k) calculated in step 45 described later two sample cycles before, and the calculation in step 45 is as described above. Integral element P1
(Z ^-1 ), and using the value two sample periods earlier corresponds to the operation of the dead time element P2 (z ^-1 ). Since y3 (k) is a driving force affected by the running resistance obtained from the actual vehicle speed Vsp, and driving force y2 (k-2) is a driving force not affected by the running resistance obtained in the compensator. The difference between the two becomes the estimated running resistance Fr. As described above, the disturbance estimator configured by the approximate zeroing technique can accurately estimate disturbance such as running resistance based on the difference between the output of the controlled object model and the actual output of the controlled object.

In step 44, the final target driving force y1 is limited within the upper and lower limits. First, the maximum engine torque Temax and the minimum engine torque Temin corresponding to the current engine rotation speed Ne are obtained by using a data table in which the engine torque when the throttle is fully opened and when the throttle is fully closed is measured for each engine rotation speed. Next, from the maximum engine torque Temax and the minimum engine torque Temin, the maximum driving force Fmax and the minimum driving force Fmi are calculated by the following equations.
Find n.

Fmax = Temax · Gm · Gf / Rt, Fmin = Temin · Gm · Gf / Rt where Gm is the gear ratio of the transmission, Gf is the final gear ratio, and Rt is the effective radius of the tire. Then, the final target driving force y1 is limited within the maximum driving force Fmax and the minimum driving force Fmin.

If y1 (k) ≧ Fmax, y5 (k) =
If Fmax, y1 (k) ≦ Fmin, y5 (k) = Fmi
If n, Fmin <y1 (k) <Fmax, y5 (k)
= Y1 (k)

As described above, by limiting the final target driving force to within the upper and lower limit values, a steep ascending slope occurs during the constant speed traveling control, and the driving force becomes insufficient even at the maximum driving force of the vehicle, and the actual vehicle speed is reduced. Even if the vehicle speed decreases from the target vehicle speed, the final target driving force input to the disturbance estimator is limited so as not to exceed the actual maximum driving force, and does not become a large target driving force that cannot be actually obtained. No error is accumulated inside the disturbance estimator. Therefore, even after returning to the flat road, the disturbance estimator does not function quickly and the actual vehicle speed does not overshoot. Similarly, even in the case where the vehicle goes down steeply during cruise control and the braking force is insufficient even with the maximum engine braking force, and the actual vehicle speed exceeds the target vehicle speed, the final target input to the disturbance estimator is also used. Since the driving force is limited so as not to be smaller than the actual minimum driving force and does not become a large engine braking force that cannot be actually obtained, no error is accumulated inside the disturbance estimator. Therefore, even after returning to the flat road, the disturbance estimator does not function quickly and the actual vehicle speed does not undershoot.

In step 45, a part corresponding to the compensator C1 (z ^-1 ) as a low-pass filter which is a part of the disturbance estimator is operated.

## EQU10 ## y2 (k) =. Gamma.y2 (k-1) + (1-
γ) · y5 (k−1) With the above, the calculation of the vehicle speed feedback compensator shown in FIG. 7 is completed, and the process returns to step 9 in FIG.

Next, the calculation of the throttle opening will be described with reference to FIG. In step 51, a target engine torque (target engine torque) Ter is calculated from the target driving force y1, as shown in FIG.

Where Gm is the gear ratio of the transmission, Gf is the final gear ratio, and Rt is the effective radius of the tire.

Next, at step 52, a throttle opening command value corresponding to the engine torque command value Ter and the engine speed Ne is looked up from the engine non-linear steady-state characteristic map. As described above, the rate of change of the throttle opening with respect to the torque change is large near the maximum torque due to the non-linear characteristics of the engine. Therefore, during acceleration or traveling on an uphill road, the throttle opens greatly with a small increase in the torque command value. Therefore, the return of the throttle is delayed at the end of acceleration or at the end of uphill, and an overshoot of the vehicle speed occurs. Therefore, in this embodiment, the map shown in FIG. 11 is used as the engine non-linear steady-state characteristic map for performing the lookup operation of the throttle opening command value. That is, when the engine torque command value exceeds a predetermined value, the throttle opening is made constant so that the opening does not increase any more. Initially, for example, 90% of the maximum torque is set as a predetermined value for preventing the throttle from being fully opened,
Thereafter, it is changed according to the following various conditions.

That is, if the constant speed control flag is set in steps 53 → 54 → 55 and the estimated acceleration value falls below the threshold value Th1 on the deceleration side, the calculation is performed in step 51. The target engine torque Ter is set to the predetermined value for preventing the throttle from being fully opened. Here, the estimated acceleration value is shown in FIG.
A part of the robust estimator C2 (z ^-1 ) of the disturbance estimator shown in FIG.
, That is, a value obtained by dividing the driving force y3 affected by disturbance (running resistance or the like) calculated from the actual vehicle speed Vsp by the average vehicle weight M. FIG.
Reference numeral 2 denotes changes in the actual vehicle speed, the estimated acceleration value, and the target engine torque when the vehicle approaches a steep uphill while traveling at a constant speed on a flat road. At this time, the actual vehicle speed gradually decreases from the target vehicle speed, and the target engine torque gradually increases. The target engine torque at the time when the estimated acceleration value falls below the threshold value 1 (Th1) on the deceleration side is set to the predetermined value.

If the constant speed control flag is set in steps 53 → 54 → 56 → 55 and the actual vehicle speed Vsp falls below the target vehicle speed Vspr by a threshold value Th3 or more, the routine proceeds to step 51. The calculated target engine torque Ter is set to the above-mentioned predetermined value for preventing the throttle from being fully opened. FIG. 13 shows changes in the actual vehicle speed and the target engine torque when the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road. At this time, the actual vehicle speed gradually decreases from the target vehicle speed, and the target engine torque gradually increases. Actual vehicle speed is threshold value 3 more than target vehicle speed
(Th3) The target engine torque at the time of the decrease is set to the predetermined value.

In steps 53 → 57 → 58 → 55, the acceleration control flag is set, and if the estimated acceleration value is lower than the target acceleration by more than the threshold value Th2, the calculation is performed in step 51. The target engine torque Ter is set to the predetermined value for preventing the throttle from being fully opened. Here, the target acceleration is an increase / decrease rate of the target vehicle speed Vspr. FIG. 14 shows changes in the estimated acceleration value and the target engine torque when the vehicle is accelerated from the constant speed traveling. At this time, as the actual vehicle speed lags behind the target vehicle speed, the estimated acceleration value gradually decreases from the target acceleration, and the target engine torque gradually increases. The target engine torque at the time when the estimated acceleration value decreases from the target acceleration by the threshold value 2 (Th2) or more is set to the predetermined value.

In steps 53 → 57 → 58 → 59 → 55, the accelerated control flag is set, and
And the actual vehicle speed Vsp is greater than the target vehicle speed Vspr by the threshold Th.
If it has decreased by four or more, the target engine torque Ter calculated in step 51 is set to the predetermined value for preventing the throttle from being fully opened. FIG.
Indicates a change in the target engine torque when the vehicle is accelerated from the constant speed traveling. At this time, as the actual vehicle speed lags behind the target vehicle speed, the target engine torque gradually increases. The target engine torque at the time when the actual vehicle speed falls below the target vehicle speed by a threshold value 4 (Th4) or more is set to the predetermined value.

FIGS. 16 to 19 show the results of vehicle speed control at the end of acceleration and at the end of uphill in this embodiment. FIG. 16 shows changes in the actual vehicle speed, the estimated acceleration value, and the throttle opening when the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road. When the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road, as the actual vehicle speed falls below the target vehicle speed, the target engine torque is increased to control to open the throttle. However, even if the target engine torque exceeds the value at the time when the estimated acceleration value becomes lower than the threshold value 1 on the deceleration side, the throttle opening is kept constant and the throttle is not opened any more, so that climbing the slope is not possible. The throttle can be quickly closed when the vehicle ends on a flat road or a downhill, and the vehicle speed overshoot can be sufficiently suppressed.

FIG. 17 shows changes in the actual vehicle speed and the throttle opening when the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road. When the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road, as the actual vehicle speed falls below the target vehicle speed, the target engine torque is increased to control to open the throttle. However, even if the target engine torque exceeds the value at the time when the actual vehicle speed has decreased by more than the threshold value 3 from the target vehicle speed, the throttle opening is kept constant and the throttle is not opened any more. To close the throttle quickly on a flat road or downhill,
Overshoot of the vehicle speed can be sufficiently suppressed.

FIG. 18 shows changes in the estimated acceleration value and the throttle opening when the vehicle is accelerated from the constant speed running. When the vehicle speed is accelerated from the constant speed traveling, as the actual vehicle speed falls below the target vehicle speed, the target engine torque is increased to control to open the throttle. However, even if the target engine torque exceeds the value at the time when the estimated acceleration value falls below the target acceleration by the threshold value 2 or more, the throttle opening is kept constant and the throttle is not opened any more. Upon completion, the throttle can be closed quickly, and overshoot of the vehicle speed can be sufficiently suppressed.

FIG. 19 shows the change in the throttle opening when the vehicle is accelerated from the constant speed running. When accelerating from constant speed driving,
As the actual vehicle speed falls below the target vehicle speed, the target engine torque increases to control to open the throttle. However, even if the target engine torque exceeds the value at the time when the actual vehicle speed drops below the target vehicle speed by 4 or more, the throttle opening is kept constant and the throttle is not opened any more, so acceleration is completed. When this happens, the throttle can be quickly closed, and the overshoot of the vehicle speed can be sufficiently suppressed.

In the configuration of the above embodiment, the controller 14 controls the torque calculating means, the opening degree calculating means and the changing means by the controller 14, the vacuum valve 8, the vent valve 10 and the negative pressure type throttle actuator 1.
Constitute the opening control means.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a flowchart illustrating vehicle speed control according to one embodiment.

FIG. 3 is a flowchart showing acceleration control.

FIG. 4 is a flowchart showing coast control.

FIG. 5 is a flowchart showing a target driving force calculation.

FIG. 6 is a flowchart showing a throttle opening calculation.

FIG. 7 is a block diagram illustrating vehicle speed feedback control.

FIG. 8 is a block diagram showing a simplified nonlinear model of a vehicle power train.

FIG. 9 is a diagram showing a reference model.

FIG. 10 is a diagram showing calculation of a throttle opening command value.

FIG. 11 is a diagram showing an engine non-linear steady-state characteristic map.

FIG. 12 is a diagram showing changes in the actual vehicle speed, the estimated acceleration value, and the target engine torque when the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road.

FIG. 13 is a diagram showing changes in the actual vehicle speed and the target engine torque when the vehicle is approaching a steep uphill while traveling at a constant speed on a flat road.

FIG. 14 is a diagram showing changes in an estimated acceleration value and a target engine torque when the vehicle is accelerated from a constant speed running.

FIG. 15 is a diagram showing a change in target engine torque when the vehicle is accelerated from a constant speed running.

FIG. 16 is a diagram showing changes in the actual vehicle speed, the estimated acceleration value, and the throttle opening when approaching a steep uphill while traveling at a constant speed on a flat road.

FIG. 17 is a diagram showing changes in the actual vehicle speed and the throttle opening when the vehicle approaches a steep uphill while traveling at a constant speed on a flat road.

FIG. 18 is a diagram illustrating changes in an estimated acceleration value and a throttle opening when the vehicle is accelerated from constant-speed running.

FIG. 19 is a diagram showing a change in the throttle opening when the vehicle is accelerated from a constant speed running.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative pressure type throttle actuator 2 Housing 3 Diaphragm 4 Negative pressure chamber 5 Spring 6 Throttle chamber 7 Throttle valve 8 Vacuum valve 9 Vacuum valve solenoid 10 Vent valve 11 Vent valve solenoid 12 Safety valve 13 Safety valve solenoid 14 Controller 15 Microcomputer (CPU) 16 Memory 17 Throttle sensor 18 Vehicle speed sensor 19 Engine speed sensor 20 Main switch 21 Set switch 22 Accelerate switch 23 Coast switch 24 Cancel switch 25 Brake switch

Claims (6)

[Claims] 1. A torque calculation means for calculating a target engine torque based on a deviation between an actual vehicle speed and a target vehicle speed, and an opening calculation for calculating a target throttle opening from the target engine torque by using an engine non-linear steady-state characteristic map. Means for controlling the throttle valve so that the actual throttle opening becomes the target throttle opening. A vehicle speed control device for a vehicle, comprising: A vehicle speed control device for a vehicle, characterized in that the target throttle opening is set to be constant when the value exceeds a predetermined value. 2. The vehicle speed control device according to claim 1, further comprising a change unit that changes the predetermined value according to a state of the vehicle. 3. The vehicle speed control device according to claim 2, further comprising: acceleration estimation means for estimating an acceleration of the vehicle, wherein the changing means sets a threshold value of the acceleration value during a constant-speed running control. The vehicle speed control device for a vehicle, wherein the target engine torque at a time point when the engine torque falls below 1 is set to the predetermined value. 4. The vehicle speed control device for a vehicle according to claim 2, further comprising: acceleration estimation means for estimating the acceleration of the vehicle, wherein said changing means determines that said acceleration estimated value is larger than a target acceleration during acceleration control. The vehicle speed control device for a vehicle, wherein the target engine torque at the time when the value decreases by 2 or more is set to the predetermined value. 5. The vehicle speed control device for a vehicle according to claim 2, wherein the changing means changes the target engine torque when the actual vehicle speed falls below the target vehicle speed by a threshold value 3 or more during the constant speed traveling control. The vehicle speed control device for a vehicle, wherein the predetermined value is set. 6. The vehicle speed control device for a vehicle according to claim 2, wherein the changing means sets the target engine torque when the actual vehicle speed falls below the target vehicle speed by at least a threshold value 4 during acceleration control. A vehicle speed control device for a vehicle, which is set to a value.