JP2846754B2 - Vehicle travel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control device for a vehicle having a continuously variable transmission and a method for controlling a constant speed traveling.

[0002]

2. Description of the Related Art In recent years, a continuously variable transmission (CVT: Continuously Variable Variable Transmission) having a greater degree of freedom in control has been used as a vehicle transmission in place of a conventional stepped automatic transmission.
Transmission) is being actively developed. As this type of device, a V-belt type continuously variable transmission described in Japanese Patent Publication No. 2-45062 is generally used. The control method of this continuously variable transmission is such that the throttle opening (or the intake pipe negative pressure or the mass air flow rate) is stored in the control device of the transmission.
A curve connecting the optimal fuel efficiency points of the engine performance characteristics with respect to the two variables of the engine speed and the engine speed is mapped and stored, and this is always referred to to determine only the gear ratio. It is something to drive.

[0003] In Japanese Patent Publication No. Hei 2-11450,
A constant-speed traveling control device that automatically controls a throttle actuator of an engine to keep a vehicle speed constant when a driver presses a constant-speed traveling mode button or the like to indicate the intention of constant-speed traveling is disclosed. In this publication, a method is disclosed in which an engine control device is cooperatively controlled together with a constant speed traveling control device.

[0004]

However, if the above-described stepless transmission and the constant speed traveling control device are simply used together, the following problems occur in the constant speed traveling mode. In other words, the continuously variable transmission basically controls the engine speed to converge on the low speed side during steady running other than kickdown, so that the speed ratio is relatively high. For this reason, in the constant speed mode, when disturbance such as a steep ascending slope and an increase in load occurs, even if only the throttle opening is increased, the rise of the drive torque is slow, and the disturbance settling ability is reduced. There is a problem that it is low. This manifests itself as a remarkable problem particularly in the case of performing optimal fuel economy control with a continuously variable transmission. That is, in such a state, in the traveling state of the constant-speed traveling mode, the gear is normally in a high gear, so even in this state, even if only the throttle opening is increased to respond to disturbance, the rise of the drive wheel torque does not increase. It becomes extremely dull.

[0005] In addition, the slow rise of the drive wheel torque is limited to the maximum allowable input torque allowed for the input of the belt of the current V-belt type continuously variable transmission. It is also due to the fact that it cannot be done.
That is, the speed responsiveness at the time of high gear cannot be improved even if only the throttle opening degree is increased with respect to the engine whose maximum torque is not so large.

The present invention has been made in view of such a problem, and even if a disturbance enters the vehicle in the constant speed traveling mode and the vehicle speed changes, the vehicle speed can be immediately set to the vehicle speed set by the driver, and the disturbance setting ability is improved. It is an object of the present invention to provide a travel control device for a high vehicle and a constant-speed travel control method.

With respect to the above-described problems, in the case of a stepped transmission, first, the throttle opening is increased so as to minimize the occurrence of a shock due to a change in the speed during traveling at a constant speed. Only when it cannot be maintained, a method of shifting down the number of gears by one step, such as releasing overdrive, has already been established.

[0008]

In order to solve the above-mentioned problems, according to the present invention, the constant speed traveling control device and the speed ratio control device cooperate to provide an engine load correlation amount (for example, , Throttle opening) together with the gear ratio. More specifically, a traveling control device for a vehicle for solving the above-mentioned problem is provided with a constant speed that directly or indirectly represents an engine load so as to maintain a vehicle speed set by a driver. Travel control means, stepless speed change control means for controlling the speed ratio of the continuously variable transmission, and when changing the marginal driving force and speed ratio when the engine load correlation amount is changed during constant speed running control A spare driving force estimating means for estimating the spare driving force of the vehicle, and comparing the two estimated spare driving forces, the engine load correlation amount or the gear ratio, which is the control amount of the larger spare driving force, is given priority. Vehicle speed response priority instructing means for instructing the constant speed traveling control means and the stepless speed change control means so as to be controlled.

Another vehicle travel control device for solving the above-mentioned problem changes an engine load correlation amount that directly or indirectly represents an engine load so that a vehicle speed set by a driver can be maintained. Constant speed traveling control means, stepless speed change control means for controlling a speed ratio of the stepless transmission, and changing an engine load correlation amount during constant speed traveling control.
When the drive power and gear ratio are changed
A reserve drive force estimating means for estimating the excess driving force is estimated
Compare the two extra driving powers and compare the larger
The engine load correlation amount or the gear ratio, which is a control amount.
The constant-speed traveling control means and the
And a vehicle speed response instructing the stepless shift control means.
Instructing means, fuel efficiency characteristic storage means for storing minimum fuel efficiency characteristics representing various engine conditions that result in minimum fuel efficiency, and maintaining the set vehicle speed and engine condition for achieving minimum fuel efficiency during constant speed traveling control Control amount calculating means for calculating the change amount of the engine load correlation amount and the change amount of the gear ratio based on the minimum fuel efficiency characteristic, and the calculated change amount of the engine load correlation amount to the constant speed traveling control means. And a fuel efficiency priority instructing means for instructing the gear ratio control means of the calculated change amount of the gear ratio.

[0010] Still another vehicle traveling control device for solving the above-mentioned problems includes various means constituting the vehicle traveling control device described above and a driving operation in accordance with a driver's instruction or in advance. According to a state, there is provided a mode switching means for executing one of the surplus driving force estimation means and the control amount calculation means.

[0011]

According to the present invention, the engine load is controlled by the constant-speed cruise control means when the disturbance occurs during the constant-speed cruise control by coordinating the constant-speed cruise control means with the stepless speed-change control means. Since the speed change control means controls the speed ratio to control both the engine load and the speed ratio, the disturbance setting ability can be enhanced.

Specifically, in the vehicle having the vehicle speed response priority instructing means, the surplus driving force estimating means firstly outputs the surplus driving force when the engine load correlation amount is changed during the constant speed traveling control. And the extra driving force when the gear ratio is changed. Next, the instructing means compares the two estimated spare driving forces, and controls the constant-speed running control so that the engine load correlation amount or the gear ratio, which is the control amount of the larger spare driving force, is preferentially controlled. To the means and the stepless speed change control means. The constant speed traveling control means and the stepless speed change control means respectively control the engine load correlation amount and the gear ratio in accordance with the instruction.

In the vehicle having the fuel efficiency priority instructing means, the fuel consumption is first set by the control amount calculating means so that the set vehicle speed and the engine state which minimizes the fuel efficiency can be substantially maintained during the constant speed running control. The change amount of the engine load correlation amount and the change amount of the gear ratio are calculated based on the minimum fuel consumption characteristics stored in the characteristic storage means. Next, the instructing means instructs the constant speed traveling control means of the calculated change amount of the engine load correlation amount, and instructs the calculated change ratio of the gear ratio to the gear ratio control means. The constant speed traveling control means and the stepless speed change control means respectively control the engine load correlation amount and the gear ratio in accordance with the instruction. As described above, since the engine load correlation amount and the gear ratio are controlled based on the minimum fuel consumption characteristics, it is possible to enhance the disturbance setting capability and the fuel consumption. In this control, unlike the one having the vehicle speed response priority instructing means, the engine load correlation amount and the gear ratio are not preferentially controlled to the one that is effective for increasing the vehicle speed response. However, the vehicle speed response is inferior to that having the vehicle speed response priority instructing means.

Further, in the apparatus having the mode switching means, when the mode switching means instructs the mode switching from the surplus driving force estimating means and the control amount calculating means from the driver, or Execution of one calculation is instructed according to the set driving state (vehicle speed or the like). Therefore, the vehicle speed responsiveness priority control and the fuel efficiency priority control can be made compatible.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of one embodiment of a travel control device according to the present invention. The vehicle provided with the travel control device of the present embodiment includes an engine, an engine air amount actuator 4, a continuously variable transmission 6 directly connected to an engine output shaft, and a final gear 7 connected to the continuously variable transmission 6. And the driving wheels 3 connected via the driving wheels. Further, the vehicle includes a throttle opening sensor 13 for detecting a throttle opening of the engine air amount actuator 4, an engine speed sensor 16 for detecting an engine speed, and a rotation of a driven pulley in the continuously variable transmission 6. Pulley rotational speed sensor 18 for detecting the number of wheels, and driving wheel 3 for detecting the vehicle speed.
And a vehicle speed detection sensor 17 for detecting the rotation speed of the vehicle.

The traveling control device includes a continuously variable transmission control unit 5 for controlling a speed ratio of a continuously variable transmission 6, a constant speed traveling control unit 1 for traveling at a constant speed, and controls an ignition timing and a fuel-air ratio of an engine. An engine control unit 11 performs a running resistance estimating unit 12 for estimating a running resistance of the driving wheels 3 and a fuel efficiency evaluation unit 15 for performing various calculations related to fuel efficiency. The units 1, 5,... Of the travel control device are mutually connected by a bus 9. In this way, the units 1, 5,...
By making it possible to exchange signals with each other, it is possible to make each unit 1, 5,... Mutually cooperate. Also, as shown in FIG. 2, each of the units 1, 5,... Includes a CPU 21 for performing various calculations and the like, a ROM 22 storing programs and data for the calculations performed by the CPU 21, a RAM 23, It has a port 24 and an input port 25. In this embodiment, the CPU 21 and the like are provided for each of the units 1, 5,..., But if the functions are not basically impaired, the units 1, 5,. The travel control device may be configured by a CPU or the like.

The constant speed traveling control unit 1 controls the engine air amount actuator 4 in accordance with an instruction from the traveling mode setting device 2 so that the vehicle speed always converges to the speed set by the driver. As the air amount actuator, an electronic control throttle may be used as shown in the figure, or a pressure bellows type may be used. The stepless speed change control unit 5 sequentially controls the ratio between the engine output shaft speed, which is the input speed of the stepless transmission 6, and the output speed of the final gear 7, that is, the speed change ratio. Running resistance estimation unit 1
The ROM 22 stores a map for calculating the engine output torque from the throttle opening and the engine speed, which indirectly represents the engine load, as shown in FIG. 4 to 7 are stored in the ROM 22.
A program for executing the flow shown in FIG. As the throttle opening used as a parameter of the map, as long as it has a certain correlation with the engine load, for example, a mass flow rate of intake air or a negative pressure amount of an intake manifold is used. You may. In the ROM 22 of the fuel efficiency evaluation unit 15, information relating to the optimum annual fuel efficiency as shown in FIG. 8 is registered.
The ROM 22 stores a program for executing the flow shown in FIG.

Next, the vehicle speed response priority control in the constant speed running mode will be described with reference to FIGS.
FIG. 3 is a graph showing the relationship between the engine output torque Te and the engine speed Ne. The first quadrant in the figure shows the relationship between the engine output torque Te and the engine speed Ne, and the engine output performance is shown by an equi-throttle opening degree line as shown in the figure (where θ _WOT is the throttle fully open). It is a curve.). The second quadrant in the figure shows the conversion relationship between the engine output torque Te and the net torque Te 'actually transmitted to the drive wheels. Usually, this conversion coefficient is the transmission efficiency η, and η is represented by the product of the transmission efficiency η _{CVT of the continuously} variable transmission 6 and the transmission efficiency η _f of the final gear 7. However, for the convenience of the description of the present embodiment, this η is considered to be included in the engine drag torque T _{D. In} this quadrant, the inclination of η is almost 1, and Te ′ is the engine immediately below the engine output shaft. It is assumed to be equal to the output torque Te (that is, the input torque of the continuously variable transmission 6).

The fourth quadrant in the figure shows the relationship between the engine speed Ne and the vehicle speed VSP. The inclination of a straight line connecting the operating point (point representing the current driving state of the vehicle) in the quadrant and the origin is the speed ratio i. Note that the speed ratio i also includes the speed ratio of the final gear 7. That is, the transmission ratio i _CVT of the continuously variable transmission 6, when the gear ratio of the final gear 7 and i _f, the transmission ratio i becomes i _CVT · i _f. The third quadrant of the figure shows the engine drag torque <br/> click T _D with respect to the vehicle speed VSP of the vehicle. The drag torque T _D is obtained by calculating the running resistance D of the driving wheel 3 by the total transmission ratio i _CVT · _if and the total transmission efficiency η _CVT.
A value obtained by dividing by a product of η _f , that is, a drag torque with respect to the engine output when the engine is viewed from the input shaft side of the continuously variable transmission 6. Accordingly, the speed ratio of the continuously variable transmission 6 is Kaware also changes the magnitude of the drag torque T _D. By the way, the driving state in which the magnitudes of Te ′ and T _D are balanced is the stable point, and the vehicle can maintain the vehicle speed at that time.
If Te ′> T _D , the vehicle generates a marginal driving force for acceleration, and the vehicle speeds up. Te 'if <T _D, the vehicle decelerates receives the drag by the running resistance.

The vehicle speed responsiveness priority control in the constant speed running mode will be described with reference to the flowcharts shown in FIGS. Now, it is assumed that the operating state is such that various parameters Te, Ne,... In FIG. However, in the following description, it should be noted that the condition is established even when the current state of the extra driving force estimation is not the balanced state. The flow shown in FIGS. 4 to 7 is periodically executed by the CPU 21 of the running resistance estimation unit 12 according to the program stored in the ROM 22 therein.

First, a running resistance D estimation program shown in FIG. 4 is executed. In step 30, the map Te = f (θ, N) stored in the ROM 22 of the running resistance estimation unit 12
e), the throttle valve opening θ, and the engine speed sensor 1
The current engine output torque Te is obtained from the engine speed Ne obtained from Step 6. Note that the map Te = f (θ, Ne)
Is data corresponding to the iso-throttle opening line in the first quadrant in FIG. This map, as described above,
And Ne may be stored based on the values of the mass air flow rate Qa or the intake manifold negative pressure PB instead of θ. Instead, in the latter case, the control amounts for moving the engine air amount actuator 4 are Qa and PB, respectively. Next, in step 31, the drive wheel output torque To is obtained using (Equation 1). That is, the engine output torque
Convert Te to a value based on the driving wheel side.

[0022]

(Equation 1)

Here, i ₁ is the current gear ratio of the continuously variable transmission 6, η ₁ is the transmission efficiency of the continuously variable transmission 6 at that time, and _if is the gear ratio of the final gear 7. i ₁ is obtained based on signals from the engine speed sensor 16 and the driven pulley speed sensor 18, and η ₁ is stored in the ROM 22 in the form of a table for the speed ratio i ₁ .

In step 32, based on the signal from the vehicle speed sensor 17, the vehicle acceleration dV / dt is obtained by the least square method. That is, the inclination of the vehicle speed with respect to time is calculated by linear regression. As a result, it is possible to calculate acceleration that is not affected by road surface noise. In step 33, the running resistance D in the driving wheel 3 is obtained by solving the equation of motion of (Equation 2) from the driving wheel output torque To and the acceleration dV / dt obtained above.

[0025]

(Equation 2)

Here, r is the effective dynamic radius of the drive wheel 3, W is the weight of the vehicle body, ΔW is the inertia of the rotating part equivalently replaced by the increase in weight, and g is the gravitational constant. The running resistance D is obtained by the above steps.

Next, a program for estimating the marginal driving force _TiM when the gear ratio i is changed, as shown in FIG. 5, is executed. In step 34, obtained from the running resistance D obtained in step 33, the engine drag torque T _D when viewed engine from the input shaft side of the continuously variable transmission 6 using equation (3).

[0028]

(Equation 3)

[0029] At step 35, as shown in the fourth quadrant in FIG. 3, obtained by using a new engine speed Ne_new in the case of a transmission ratio i ₁ of the by only changing .DELTA.i i ₂ (number 4).

[0030]

(Equation 4)

In this case, the operating state of the engine moves on the equal throttle opening line from point a to point b in the first quadrant of FIG.

In step 36, the map Te = f (θ, Ne) stored in the ROM 22 and the throttle valve opening θ
Then, a new engine output torque Te_new is obtained from Ne_new obtained in step 35. In step 37, using the equation (5), finding a new shelf engine drag torque T _D _new.

[0033]

(Equation 5)

Here, η ₂ is the transmission efficiency of the continuously variable transmission 6 with respect to the speed ratio i ₂ . By the speed ratio i is changed, drag torque T _D is changed. This will be explained with reference to FIG. 3, the state which maintains the vehicle speed constant, the operating point A on the drag torque curve of i ₁ of the third quadrant, drag i ₂ bets <br/> torque curve on It means that the vehicle state has changed to the operating point B. In step 38, the Te_new obtained in step 36, pull the T _D _new obtained in step 37 to determine the reserve drive force T _iM of varying the transmission ratio i.

Next, as shown in FIG.
It executes the estimation program reserve drive force T.theta _M when was only changed. In step 39, assuming that the engine speed Ne is unchanged from the current value, the engine speed Ne, the new throttle valve opening (θ + Δθ), and the map Te = f (θ, N
e), a new engine output torque Te_new is obtained.
This corresponds to changing the operating point of the engine from point a to point c in the first quadrant of FIG.

[0036] In step 40, by subtracting the T _D obtained in step 34 from Te_new obtained in step 39 to determine the reserve drive force T.theta _M in the case of changing the amount of air. Here, in order to determine the reserve drive force T.theta _M, as in step 38, but it should draw the T _D _new from Te_new, a case of changing the air quantity Te_new ≒ T _D _new, and the operation for simplicity, we use a T _D instead of Te_new.

_Assuming that T _iM and Tθ _M are obtained graphically,
It can be determined as follows. To find T _iM ,
First, the fourth quadrant, the vehicle speed operating point of the i ₁ speed ratio line in FIG. 3
And Δi only varied without changing the VSP well as plotted on i ₂ gear ratio line plots the point B in the same vehicle speed V and the previous operating point in the third quadrant of i ₂ drag torque on the curve. Next, a point corresponding to the point plotted on the i ₂ speed ratio line in the fourth quadrant is referred to as a first point.
Plots in quadrant, second quadrant and third quadrant respectively. When the interval between the point plotted in the third quadrant and the point B on the i ₂ drag torque curve changes the gear ratio i, the marginal driving force T
_iM . On the other hand, to obtain Tθ _M , first,
A point a corresponding to the operating point on the i ₁ speed ratio line in the quadrant is plotted in the first quadrant, and a point A of the same vehicle speed VSP as the previous operating point is plotted on the i ₁ drag torque curve in the third quadrant. Next, a point c obtained by changing the point a in the first quadrant by Δθ without changing the engine speed Ne is plotted, and a point corresponding to the point c is plotted in the second quadrant and the third quadrant.
Distance between the point A on the third points plotted in quadrants and i ₁ drag torque curve becomes reserve drive force T.theta _M when changing the amount of air.

With the above processing, two marginal driving forces T _iM , Tθ
_{Since M} has been determined, it is easy to determine whether to change the gear ratio or to move the throttle valve when a disturbance in the constant speed traveling mode is detected. This is shown in the flowchart of FIG. Step 4
At 0a, the magnitudes of the two marginal driving forces T _iM and Tθ _M are compared. When the T _iM> T.theta _M, step 41 is executed to preferentially control the gear ratio. When T _iM <Tθ _M ,
Step 42 is executed, and the air amount (throttle valve opening)
Is preferentially controlled. Here, the priority control means:
One of the prioritized control amounts is operated first, and the other control amount is operated after this is saturated. In addition, as described above, not only one of the two control amounts may be operated uniformly, but also the distribution ratio of the operations may be changed to increase one of the prioritized control amounts.

The control amount determined in this way is output from the running resistance estimating unit 12 to the constant speed running control unit 1 and the stepless speed change control unit 5, and the throttle valve opening and / or the speed ratio is controlled. For this reason, the control amount having the larger margin driving force is preferentially operated, so that even if disturbance occurs during the constant speed traveling mode, the rise of the driving wheel torque is much sharper than that in which only the throttle valve opening is changed. Become. As described above, the estimation of the marginal driving force by the present method requires only setting of at most a few drive system parameters as long as the engine torque map Te = f (θ, Ne) can be accurately set. Therefore, if the engine is the same, it can be deployed with a small amount of effort even for a plurality of vehicle models having different drive systems. It is preferable to use the minimum control amount or a value close to each of the minimum control amounts as the values of Δi and Δθ.

Next, the fuel efficiency priority control in the constant speed mode will be described with reference to FIGS. FIG.
Is obtained by further loading an equiaxed fuel consumption rate line and an optimum fuel consumption rate curve on the graph of FIG. In the first quadrant of the figure,
An equiaxed fuel consumption rate line is also shown superimposed on the iso-throttle opening degree line shown in FIG. Further, FIG. 8 also shows an optimal fuel consumption rate curve (shown by a broken line in FIG. 8) in which points at which the minimum fuel consumption is obtained on the iso-throttle opening degree line. As described above, this is stored in the ROM 22 of the fuel efficiency evaluation unit 15 in the form of a table Ne = g (θ) for converting the throttle valve opening θ into the engine speed Ne on the minimum fuel efficiency curve. I have.

When the engine state is converged on the optimum fuel efficiency curve in the constant speed running state, the desired optimum fuel efficiency control can be realized. In FIG. 8, this corresponds to moving from the operating point a in the first quadrant to a point b on the optimal fuel consumption curve side while maintaining the vehicle speed V ₀ constant (in the third quadrant in FIG. In this case, the drag torque balance point moves from point A to point B.) That is, it is equivalent to changing the gear ratio i and the throttle opening θ to perform the bivariate feedback control so that the engine state is on the optimum fuel efficiency curve.

The fuel efficiency priority control will be described with reference to the flowchart shown in FIG. The flow shown in FIG. 9 shows that the CPU 21 of the fuel efficiency evaluation unit 15
In accordance with the program stored in the. In step 50, the current vehicle speed V is, to check whether the entered into the settling speed width e _SV around the set vehicle speed V ₀ set by the driver. The set vehicle speed V ₀ is determined by the vehicle speed set by the driver at the start of the constant-speed running mode.
Is registered in the RAM 23. Also, settling vehicle speed width e _SV
Is set by the CPU 21 when the set vehicle speed V ₀ is set.
It is also registered in the RAM 23. FIG. 10 shows the relationship between the set vehicle speed width e _SV and the set vehicle speed V ₀ . In step 50, the current vehicle speed obtained from the speed sensor 17
If V is within the settling vehicle speed range e _SV, the process jumps to step 52; otherwise, the next step 51 is executed. In step 51, PID control so as to converge the vehicle speed V to the set vehicle speed V ₀ is performed, is determined a new throttle valve opening Shitanew, which via a cruise control unit 1 from the fuel consumption evaluation unit 15 Engine The air amount is transmitted to the actuator 4.

In step 52, the optimum fuel efficiency curve table Ne = g (θ) is searched, and the current throttle valve opening θnew is retrieved.
(If PID control is not performed in step 51, θnew
= Determining engine target speed Ne ₀ on the optimum fuel consumption curve corresponding to) and theta.

Next, as in the case of the vehicle speed at step 53, the current engine speed Ne is, to check whether the entered into the settling rpm width e _SV around the target rotational speed Ne _0. If it is within the set rotation speed range e _SV, the flow ends, otherwise, the next step 54 is executed. In step 54, the target speed ratio i ₀ for realizing the set vehicle speed V ₀ and the target engine speed Ne ₀ is expressed by (Equation 6).
Is calculated.

[0045]

(Equation 6)

Subsequently, at step 55, PID control is performed so that the current gear ratio i converges to the target gear ratio i ₀ , a new gear ratio inew is determined, and the fuel efficiency rate evaluation unit 15 performs stepless control. The transmission is transmitted to the continuously variable transmission 6 via the transmission control unit 5.

As described above, when disturbance occurs in the constant-speed running mode, the throttle opening and the gear ratio are controlled, so that low fuel consumption can be realized and disturbance setting ability can be enhanced. Can be. Note that the feedback gains K _P , T _I ,
T _D , K _P ′, T _I ′, and T _D ′ may be set independently of each other, or may be set so that the magnitude or deviation of one control amount affects the gain of the other. . FIG.
Considering a control plane of Te and Ne as in the first quadrant, a specific gain may be set for each corresponding operating state by dividing this plane. Further, in this embodiment, all the steps 50,..., 55 are calculated in the fuel efficiency evaluation unit 15, and only the control amount is output to the constant speed traveling control unit 1 and the continuously variable transmission control unit 5. However, the feedback control portions executed in steps 51 and 55 may be autonomously executed by the constant-speed traveling control device 1 and the continuously variable transmission control device 5, respectively.

Next, an example of selectively executing the vehicle speed response priority control and the fuel efficiency priority control described above with reference to FIG.
Explanation will be made using 0. Previously stored in the ROM22 of the settling speed width e _sv wider set the speed range than the control law switching speed width e _cm running resistance unit 12 or the fuel consumption ratio evaluating unit 15. Then, when the constant speed traveling mode is designated by the traveling mode setting device 2, until the vehicle speed within the control law switching vehicle speed width e _cm from the current vehicle speed is reached (the section from point a to point b in FIG. 10). The vehicle speed responsiveness priority control is performed, and when the vehicle speed becomes the vehicle speed within the control law switching vehicle speed width e _cm (the section from point b to point c in the figure), the fuel efficiency priority control is performed.
If the vehicle speed deviates again from the control law switching vehicle speed width e _cm due to a disturbance (in the section from the point c to the point d in the figure), the vehicle speed responsiveness priority control is performed. The CPU 21 of the running resistance unit 12 or the fuel efficiency evaluation unit 15 determines whether to execute the vehicle speed responsiveness priority control or the fuel efficiency priority control, and issues an instruction to switch these controls.

In the fuel efficiency priority control, as described above, since the throttle opening and the gear ratio are controlled, the disturbance setting ability is higher than that of simply controlling the throttle opening. The disturbance setting ability is inferior to that in which one of the throttle opening and the gear ratio is preferentially controlled based on the extra driving force. Therefore, when the vehicle speed is significantly different from the set vehicle speed V ₀ , the vehicle speed responsiveness is enhanced by performing a vehicle speed responsiveness priority control having a higher disturbance setting ability, and the vehicle speed is significantly different from the set vehicle speed V ₀ . If not, the fuel economy priority control is performed to improve the fuel economy.

The control law switching vehicle speed width e _cm may be given as a fixed constant value, or may be variable depending on the vehicle speed or the driving mode. In the above description, the control mode is switched according to the vehicle speed that represents one mode of the driving state. However, some drivers prefer only one of the control modes. Therefore, the traveling mode setting device 2 is provided with a selection means capable of selecting the above-described automatic switching control mode, the vehicle speed responsiveness control mode, and the fuel efficiency priority control mode, and according to the driver's instruction, according to the driver's preference. A corresponding control mode may be executed. As described above, when the vehicle has the vehicle speed responsiveness control mode and the fuel efficiency priority control mode, a display means for displaying a mode state may be provided in order to inform the driver which mode is being controlled. preferable. As described above, even in the case where only the fuel efficiency priority control is basically performed, as described above, after the designation of the constant speed traveling mode, immediately before the vehicle speed falls within the control law switching vehicle speed width e _cm from the current vehicle speed (FIG. 10). In the middle, the section from point a to point b), the vehicle speed responsiveness control may be always performed.

[0051]

According to the present invention, coordination is provided between the constant speed traveling control and the stepless speed ratio control, and when a disturbance occurs in the constant speed traveling mode, the engine load and the speed ratio are controlled. Is controlled, the disturbance settling ability can be increased.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a travel control device according to one embodiment of the present invention.

FIG. 2 is a circuit block diagram in each unit in FIG. 1;

FIG. 3 is an explanatory diagram illustrating a process of calculating a marginal driving force according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a running resistance estimation procedure in the vehicle speed responsiveness priority control according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a procedure for estimating a marginal driving force when the gear ratio is changed in the vehicle speed responsiveness priority control according to the embodiment of the present invention.

FIG. 6 is a flowchart showing a procedure for estimating a marginal driving force when the throttle opening is changed in the vehicle speed responsiveness priority control according to one embodiment of the present invention.

FIG. 7 is a flowchart illustrating a priority control amount determination procedure in the vehicle speed responsiveness priority control according to one embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining fuel efficiency priority control according to one embodiment of the present invention.

FIG. 9 is a flowchart showing a fuel efficiency priority control procedure according to one embodiment of the present invention.

FIG. 10 is an explanatory diagram for explaining control mode switching according to one embodiment of the present invention.

[Explanation of symbols]

1: Constant speed traveling control unit, 2: Travel mode setting device, 3
... drive wheels, 4 ... engine air amount actuator, 5 ... stepless speed change control unit, 6 ... stepless transmission, 7 ... final gear, 9 ... bus, 11 ... engine control unit, 1
2: running resistance estimation unit, 13: throttle opening sensor, 15: fuel efficiency evaluation unit.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI F02D 45/00 326 F02D 45/00 326 F16H 9/00 F16H 9/00 E (58) Fields investigated (Int.Cl. ⁶ , (DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48 B60K 41/00-41/28 B60K 31/00-31/18 F02D 29/00-29 / 06 F02D 45/00

Claims (8)

(57) [Claims] 1. A traveling control device for a vehicle having a continuously variable transmission, wherein a constant speed for directly or indirectly representing an engine load is changed so as to maintain a vehicle speed set by a driver. Traveling control means, stepless speed change control means for controlling the speed ratio of the stepless transmission, and changing the marginal driving force and speed ratio when the engine load correlation amount is changed during constant speed running control. A spare drive force estimating means for estimating a spare drive force in the case, and comparing the estimated two spare drive forces, the engine load correlation amount or the gear ratio, which is a control amount of the larger spare drive force, has priority. A vehicle speed response priority instructing means for instructing the constant speed traveling control means and the stepless speed change control means. 2. A traveling control device for a vehicle having a continuously variable transmission, wherein a constant speed for directly or indirectly representing an engine load is changed so as to maintain a vehicle speed set by a driver. Traveling control means, stepless speed change control means for controlling the speed ratio of the stepless transmission, and changing the marginal driving force and speed ratio when the engine load correlation amount is changed during constant speed running control. A spare drive force estimating means for estimating a spare drive force in the case, and comparing the estimated two spare drive forces, the engine load correlation amount or the gear ratio, which is a control amount of the larger spare drive force, has priority. Vehicle speed response priority instructing means for instructing the constant speed traveling control means and the stepless speed change control means, and a minimum fuel consumption characteristic representing various engine states which minimize the fuel consumption. A fuel efficiency characteristic storage means for storing the set vehicle speed and the change amount of the engine load correlation amount and the gear ratio based on the minimum fuel efficiency characteristic so that the engine state with the minimum fuel efficiency can be substantially maintained during the constant speed traveling control. Control amount calculating means for calculating a change amount; and instructing the constant speed traveling control means with the calculated change amount of the engine load correlation amount, and instructing the gear ratio control means with the calculated change amount of the gear ratio. Fuel economy priority instructing means; mode switching means for executing one of the marginal driving force estimating means and the control amount calculating means in accordance with a driver's instruction or in accordance with a preset driving state; A travel control device for a vehicle, comprising: 3. The vehicle speed response priority instructing means instructs that a priority control amount is operated first, and that the other control amount is operated after the priority control amount is saturated. 3. The travel control device for a vehicle according to claim 1 or 2 . 4. The vehicle speed response priority instructing means instructs an operation ratio between a priority control amount and the other control amount so that an operation ratio of the priority control amount increases. 3. The travel control device for a vehicle according to claim 2 . 5. A correlation storage means for storing a correlation between an engine output torque, an engine load correlation amount, and an engine speed, which is obtained in advance, the speed change ratio and a vehicle speed. An engine speed calculating means for calculating the engine speed from the following, an engine speed and a current engine load correlation amount when the gear ratio is changed, and an engine when the current engine speed and the engine load correlation amount are changed An engine output torque estimating means for calculating the corresponding engine output torque from the load correlation amount using the correlation, a running resistance of the driving wheel and a changed gear ratio, and a running resistance of the driving wheel and a current speed. and a gear ratio, the engine drag <br/> torque estimating means for calculating an engine drag torque corresponding to the respective output the engine is calculated From torque, the calculated by subtracting the engine drag torque, any means for calculating the excess driving force from claim 1, characterized in that it comprises a fourth
The travel control device for a vehicle according to claim 1 . 6. The engine according to claim 1, wherein the engine load correlation amount is a throttle valve opening .
A travel control device for a vehicle according to claim 1 . 7. said engine, said continuously variable transmission connected to the engine, any one of claims 1 to control the status of these 6
Vehicle, characterized in that it comprises a and a traveling device for a vehicle according to. 8. A constant speed traveling control method for a vehicle having a continuously variable transmission, wherein a margin when an engine load correlation amount directly or indirectly representing an engine load is changed during constant speed traveling control. Estimate the marginal driving force when the driving force and the gear ratio are changed, compare the two estimated marginal driving forces, and calculate the engine load correlation amount or the gear ratio, which is the control amount of the larger marginal driving force. A driving control method for a vehicle, wherein the driving control is performed with priority.