JP2000248973A - Drive force control device for vehicle equipped with continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a negative drive force command value or a negative drive torque command value, while satisfying limit of an engine speed with the condition of a vehicle. SOLUTION: When a drive force command value or a drive torque command value is negative, an engine speed limited by the condition of a vehicle is considered, the condition of an engine is set to any of the condition of fully closing a throttle valve and with a fuel cut inhibited (condition 1), the condition of fully closing the throttle valve and with the fuel cut (condition 2), and the condition of fully opening the throttle valve and with the fuel cut (condition 3). In this way, a negative drive force command value or a negative drive torque command value determined by an accelerator operating amount by a driver, car speed control, inter-vehicle distance control, etc., can be realized, while satisfying the limit of the engine speed by the condition of the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force control device for a vehicle equipped with a continuously variable transmission.

[0002]

2. Description of the Related Art In a vehicle equipped with a continuously variable transmission, if the vehicle speed deviation is smaller than a predetermined value, only the throttle valve opening is controlled, and if the vehicle speed deviation is larger than a predetermined value, only the speed ratio is controlled. Such a vehicle speed control device is known (for example, refer to Japanese Patent Application Laid-Open No. 61-232927). In this device, two inputs of the throttle valve opening and the gear ratio are not simultaneously controlled.

Further, in a vehicle equipped with a continuously variable transmission, a combination capable of realizing optimum fuel efficiency is calculated from a combination of engine torque and gear ratio for realizing a driving force necessary for maintaining a vehicle speed command value. There is disclosed a control algorithm for controlling the throttle valve opening and the gear ratio (for example, VOL. 48, No. 10, 199 of the Society of Automotive Engineers of Japan).
4). In this control, a vehicle speed command value is achieved by simultaneously controlling two inputs of a throttle valve opening and a gear ratio. However, this device is not effective for a negative driving force command value.

Further, when the engine cooling water temperature is low,
2. Description of the Related Art When the charge amount of a battery is low, a technology for increasing the rotation speed of the engine to promote warming-up of the engine and charging of the battery is known. There is also known a technique in which the resonance point is shifted by changing the rotation speed of an engine in order to prevent a noise generated at a low vehicle speed.

[0005]

However, in a conventional driving force control device for a vehicle equipped with a continuously variable transmission, when a negative driving force command value is required, the throttle valve is fully closed and the fuel cut-off is performed. Can only respond by raising the gear ratio (shifting down) in the specific state of
Therefore, the operating point of the engine is limited to one point, and the engine speed is increased to warm up the engine or charge the battery, or the engine speed is shifted from the resonance point to prevent muffled noise. There is a problem that can not be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle with a negative driving force command value or a negative driving force determined by an accelerator operation amount, a vehicle speed control, an inter-vehicle distance control, etc., while satisfying a restriction on an engine rotation speed depending on a vehicle state. It is to realize a torque command value.

[0007]

The present invention will be described with reference to FIG. 1 showing the configuration of an embodiment. (1) The invention of claim 1 provides a driving force command value or a driving torque command value of a vehicle. Command value determining means 12 for determining a driving force command value or a driving torque command value, a command value calculating means 12 for calculating an engine torque command value and a gear ratio command value, and an engine torque command value Continuously variable transmission comprising an engine control means 13 for controlling the engine 9 so as to match the speed ratio and a continuously variable transmission control means 14 for controlling the continuously variable transmission 10 so that the speed ratio matches the speed ratio command value. Applied to the driving force control device of a vehicle equipped with a motor. When the driving force command value or the driving torque command value is negative, the state of the engine 9 is changed to the throttle valve fully closed and fuel cut prohibited state (state 1) an engine state setting means 12 for setting any one of a throttle valve fully closed and fuel cut state (state 2) and a throttle valve open and fuel cut state (state 3)
To achieve the object of the present invention. (2) In the driving force control device for a vehicle equipped with the continuously variable transmission according to the second aspect, the temperature of the engine cooling water, the charged state of the battery, the operation of the air conditioner, the lighting of the lamps, and the vehicle speed are included in the vehicle state. included. (3) In the driving force control device for a vehicle equipped with the continuously variable transmission according to the third aspect, the command
In the setting state, the operating point of the engine 9 is determined based on the driving force command value or the driving torque command value, and the gear ratio command value is calculated based on the engine operating point. (4) In the driving force control device for a vehicle equipped with the continuously variable transmission according to claim 4, the command value determining means 12 determines a driving force command value or a driving torque command value for matching the vehicle speed with the vehicle speed command value. It is something to do. (5) In the driving force control device for a vehicle equipped with the continuously variable transmission according to claim 5, the command value determining means 12 determines the driving force command value or the driving torque command value based on the accelerator pedal depression amount of the occupant. It is like that. (6) In the driving force control device for a vehicle equipped with the continuously variable transmission according to claim 6, the command value determining means 12 sets a driving force command value for matching the inter-vehicle distance with the preceding vehicle to the inter-vehicle distance command value. The drive torque command value is determined.

In the section of the means for solving the above-mentioned problems, a diagram of an embodiment is used for easy understanding of the description, but the present invention is not limited to the embodiment. .

[0009]

(1) According to the first aspect of the present invention, the engine state is set in consideration of the engine speed restricted by the vehicle state. A negative driving force command value or a negative driving torque command value can be realized while satisfying the constraint. (2) According to the second aspect of the present invention, the engine rotation speed is restricted by the temperature of the engine cooling water, the state of charge of the battery, the operation of the air conditioner, the lighting of the lamps, and the vehicle speed, and based on the restricted rotation speed. Since the state of the engine is set, an effect similar to the above effect of the first aspect is obtained. (3) According to the invention of claim 4, since the driving force command value or the driving torque command value for matching the vehicle speed with the vehicle speed command value is determined, the negative driving force command value or the negative driving torque is determined. The accuracy and responsiveness of the vehicle speed control with respect to the command value can be improved. (4) According to the invention of claim 5, since the driving force command value or the driving torque command value is determined based on the accelerator pedal depression amount of the occupant, even when the vehicle speed is controlled by the occupant operating the accelerator pedal. , Negative driving force and negative driving torque can be finely and stably realized over a wide range. (5) According to the invention of claim 6, since the driving force command value or the driving torque command value for matching the inter-vehicle distance with the preceding vehicle to the inter-vehicle distance command value is determined, the negative driving force command value is determined. The accuracy and responsiveness of the inter-vehicle distance control with respect to the value or the negative driving torque command value can be improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a vehicle equipped with a continuously variable transmission for controlling vehicle speed will be described. In this embodiment, a driving force command value and a driving torque command value are determined in vehicle speed control for making the actual vehicle speed coincide with the vehicle speed command value.

FIG. 1 shows a configuration of an embodiment. The set switch 1 is a switch for setting the current vehicle speed to a vehicle speed command value and starting vehicle speed control. Accelerate switch 2 is a switch for increasing the set vehicle speed,
Coast switch 3 is a switch for reducing the set vehicle speed. The cancel switch 4 is a switch for releasing the vehicle speed control, and the brake switch 5 is a switch that operates when a foot brake is operated. When the brake switch 5 operates, the cancel switch 4
The vehicle speed control is released in the same manner as when the is operated.

The crank angle sensor 6 outputs a pulse train signal having a cycle corresponding to the engine speed (hereinafter sometimes simply referred to as the engine speed, in which case the engine speed per unit time (for example, every minute)). The vehicle speed sensor 7 outputs a pulse train signal having a cycle corresponding to the vehicle speed.
The engine rotation speed Ne and the vehicle speed Vsp can be detected by measuring the pulse interval of these pulse train signals or the number of pulses per predetermined time. The accelerator sensor 8 detects the depression amount of the accelerator pedal as the occupant's intention to accelerate. This accelerator pedal depression amount is used for normal control when the vehicle speed control is released. The water temperature sensor 15 detects the cooling water temperature of the engine, and the SOC sensor 16 detects the state of charge S of the battery.
Detect OC.

The lean-burn engine 9 includes a throttle valve actuator 9a for controlling an intake air amount, an injector 9b for controlling a fuel injection amount, and a spark plug 9c.
Is controlled so that the engine torque matches the command value. In this lean-burn engine 9, the ideal air-fuel ratio (stoichiometric) state and the lean-burn air-fuel ratio state are discontinuously switched as shown in FIG. 2, and the low-rotation cam and the high-speed cam as shown in FIG. The rotation cam is switched discontinuously, and the opening / closing timing of the intake / exhaust valve changes discontinuously.

The belt-type continuously variable transmission 10 is controlled so that the gear ratio matches the command value by changing the radius of the primary pulley and the secondary pulley by hydraulic control. Further, the belt-type continuously variable transmission 10 includes a torque converter 11 with a lock-up clutch for starting. In this embodiment, the belt type continuously variable transmission 10 will be described as an example. However, the continuously variable transmission is not limited to the belt type, and may be a toroidal type. Further, a metal belt, a dry composite belt, or the like can be used for the belt-type continuously variable transmission.

Vehicle speed controller 12, engine torque controller 13, and gear ratio controller 1
Reference numerals 4 each include a microcomputer, peripheral components thereof, drive circuits for various actuators, and the like, and communicate with each other via a communication circuit. Vehicle speed controller 1
2 sets and changes a vehicle speed command value, calculates a torque command value and a gear ratio command value, and the like. Torque controller 13
Performs throttle valve opening control based on an engine torque command value of the engine 9 and switching control of an engine operating state such as air-fuel ratio, intake / exhaust valve opening / closing timing, and fuel cut / recovery. Further, the gear ratio controller 14 controls the continuously variable transmission 10 based on the gear ratio command value.
Control the transmission gear ratio.

FIG. 4 is a flowchart showing a vehicle speed control program, and FIG. 5 is a flowchart showing an engine rotation speed command value calculation routine when the driving force command value (or driving torque command value) is negative. The operation of the embodiment will be described with reference to these flowcharts. The vehicle speed controller 12 executes the vehicle speed control program, for example, every 10 msec. In step 1, a pulse signal from the vehicle speed sensor 7 is measured to detect the vehicle speed Vsp. In the following step 2, it is confirmed whether the cancel switch 4 or the brake switch 5 is in the ON state, that is, whether the vehicle speed control is canceled. When the vehicle speed control is released, the process proceeds to step 6, where various control flags and parameter variables are initialized, and the vehicle speed control is terminated.

If the vehicle speed control has not been released, the routine proceeds to step 3, where it is confirmed whether the set switch 1 has been operated. When the set switch 1 is ON, the process proceeds to step 4, where the current actual vehicle speed Vsp is set to the vehicle speed command value Vspr and stored in order to start the vehicle speed control. Next, at step 5, a flag indicating that the vehicle speed is being controlled (ASCD operation flag) is set, and the process is terminated once.

When the set switch 1 is off, the routine proceeds to step 7, where it is confirmed from the ASCD operation flag whether or not the vehicle speed control is being performed. If the ASCD flag has not been set, the process proceeds to step 6, where various control flags and parameter variables are initialized, and the vehicle speed control ends. When the ASCD flag is set, the routine proceeds to step 8, where a driving force command value y1 and a driving torque command value Tor for making the actual vehicle speed Vsp coincide with the vehicle speed command value Vspr are calculated.

FIG. 6 is a control block diagram showing vehicle speed feedback control according to one embodiment. The method of calculating the driving force command value y1 and the driving torque command value Tor 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.
The vehicle model (formulaized model) to be controlled incorporated in the vehicle speed feedback compensator is modeled with the driving force command value y1 as an operation amount and the vehicle speed Vsp as a control amount, so that an engine with a relatively quick response is obtained. And the transient characteristics of the torque converter and the nonlinear steady-state characteristics of the torque converter. Then, a throttle valve opening command value TVOr such that the driving force of the vehicle matches the driving force command value y1 is calculated using a previously measured engine non-linear steady-state characteristic map as shown in FIG. The servo non-linear characteristic of the engine can be linearized by servo-controlling the valve opening TVO. Therefore, the vehicle model that receives the driving force command value y1 and outputs the vehicle speed Vsp has an integral characteristic, and the compensator can set the transfer characteristic of this vehicle model to the pulse transfer function P (z ⁻¹ ).

In FIG. 6, z is a delay operator, and z
^When multiplied by ^-n (n = 1, 2,...), the value becomes the value of n sampling cycles before. 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 a model matching method. As shown in FIG. 8, a response characteristic of a control target when a vehicle speed command value Vspr is input and an actual vehicle speed Vsp is output is represented by a predetermined first-order lag and dead time element. The characteristic is matched with the characteristic of the reference model H (z ^-1 ).

It is necessary to consider the dead time, which is the delay of the power train, as the transfer characteristic of the control object. The pulse transfer function P (z ^-1 ) of the control object that receives the driving force command value y1 and outputs the actual vehicle speed Vsp is represented by an integral element P1
(Z ^-1 ) and the dead time element P2 (z ^-1 ) (= z ^-n ).

P1 (z ⁻¹ ) = T · z ⁻¹ / {M · (1-z ⁻¹ )}, P (z ⁻¹ ) = T · z ⁻¹ · z ⁻ⁿ / ｛M · ( 1−z ⁻¹ ) where T is the sampling period (10 in this embodiment).
msec), M is the average vehicle weight.

At this time, the compensator C1 (z ^-1 ) is represented by the following equation.

## EQU2 ## C1 (z- ¹ ) = (1-.gamma.) Z- ¹ / (1-.gamma.z- ¹ ), .gamma. = Exp (-T / Tb) That is, 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.

C2 (z ^-1 ) = M-1 (1-γ) ・ (1-z ^-1 )
/ {T · (1−γ · z ⁻¹ )} The compensator C2 is obtained by applying a low-pass filter to the inverse system of the vehicle model.
driving force according to the actual vehicle speed Vsp by inputting sp,
That is, it is possible to obtain a driving force corresponding to only the actual vehicle speed Vsp that does not include disturbance such as running resistance.

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 controlled object, the compensator C3 has the following constants.

[Mathematical formula-see original document] C3 = K = {1-exp (-T / Ta)} * M / T

Next, the model matching compensator C3
A calculation corresponding to (z ^-1 ) is performed to obtain a driving force y4 for accelerating from the actual vehicle speed Vsp to the vehicle speed command value Vspr. Assuming that data y (k) represents the driving force at the time of the current sampling, and data y (k-1) represents the driving force one sampling cycle before,

Y4 (k) = K ｛{Vspr (k) -Vsp (k)}

Further, a part corresponding to a part of the robust compensator C2 (z ^-1 ) of the disturbance estimator shown in FIG. 6 is calculated, and a disturbance such as a driving force according to the actual vehicle speed Vsp, that is, a running resistance, is generated. Driving force y3 only according to actual vehicle speed Vsp not included
Is calculated.

Y3 (k) = γ · y3 (k−1) + (1−γ) · M
{Vsp (k) -Vsp (k-1)} / T

The driving force y4 is estimated by a disturbance estimation value F such as running resistance.
The driving force command value y1 (k) is obtained by correcting with r. As described above, the driving force y3 (k) is a driving force corresponding to the actual vehicle speed Vsp,
That is, the driving force is based only on the actual vehicle speed Vsp that does not include disturbance such as running resistance. On the other hand, since the compensator C1 is a low-pass filter, the driving force y2 (k) is a driving force obtained by subjecting the driving force y5 after the limiter processing to low-pass filtering. A driving force y obtained by multiplying this driving force y2 (k) by z ^-2
2 (k−2) is the value of the driving force y2 (k) two sampling periods before, and can be regarded as the current actual driving force of the power train in consideration of the power train delay (dead time).
Therefore, the driving power y2 (k-2) of the current power train
Thus, if the driving force y3 (k) for the actual vehicle speed Vsp that does not include the disturbance such as the running resistance is reduced, the disturbance such as the running resistance can be estimated. Then, the driving force y4 (k) is corrected with the disturbance estimation value Fr such as running resistance, and the driving force command value y1 (k) for compensating for the driving force shortage due to the disturbance is obtained.

Y1 (k) = y4 (k)-{y3 (k) -y2 (k-2)} = y4 (k) + {y2 (k-2) -y3 (k)}, Fr = y2 (k-2) -y3 (k)

As described above, the disturbance estimator constituted by the approximate zeroing method 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. .

Next, the driving force command value y1 is restricted 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 calculated using a map data obtained by measuring the engine torque when the throttle valve is fully opened and fully closed for each engine rotation speed. . Further, from the maximum engine torque Temax and the minimum engine torque Temin, a maximum driving force Fmax and a minimum driving force Fmin are obtained by the following equation.

Fmax = Temax · Gmax · Gf / Rt, Fmin = Temin · Gmax · Gf / Rt where Gmax is the maximum speed ratio of the continuously variable transmission 10, Gf is the final gear ratio, and Rt is the effective radius of the wheel. It is.

The driving force command value y1 (k) is limited to within the maximum driving force Fmax and the minimum driving force Fmin to determine the driving force y5 (k).

If y1 (k) ≧ Fmax, y5 (k) = Fmax, if y1 (k) ≦ Fmin, y5 (k) = Fmin, and if Fmin <y1 (k) <Fmax, y5 (k) = y1 (k)

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

Y2 (k) = γ · y2 (k−1) + (1−γ) · y5 (k−1)

Finally, a driving torque command value Tor is calculated from the effective radius Rt of the wheel based on the driving force command value y1 (k).

## EQU11 ## Tor = y1.Rt

Returning to FIG. 4, the description of the vehicle speed control will be continued. In step 9, the sign of the driving force command value y1 or the driving torque command value Tor is checked. If it is 0 or positive, the process proceeds to step 10, and if it is negative, the process proceeds to step 11. In step 10, the operating point of the engine that realizes the positive driving force command value y1 or the driving torque command value Tor with the minimum fuel consumption is determined. First, the engine output command value L is calculated by the following equation.

L = Tor · Vspr / Rt or L = y1 · Vspr

FIG. 9 shows an engine characteristic diagram (equal output line, equal fuel consumption line, and optimum fuel consumption operation line) when the engine output and the engine torque are positive. Using such an engine characteristic diagram, the operating point at which the fuel consumption is minimized while achieving the output command value L (positive value), that is, on the optimal fuel consumption operation line connecting the contact points between the equal output line and the constant fuel consumption line Search for the operating point at. Actually, the target engine operating point corresponding to the output value (positive value), that is, the engine rotation speed command value determined by the intersection of the equal output line and the optimum fuel consumption operation line is stored in advance as map data, An engine speed command value Ner corresponding to the command value L (positive value) is obtained by a look-up calculation.

In step 11, a negative driving force command value y1
Alternatively, an engine operating point for realizing the drive torque command value Tor by permitting and prohibiting the fuel cut and opening the throttle valve is obtained. First, the engine output command value L is calculated by the following equation.

L = Tor · Vspr / Rt or L = y1 · Vspr

As described above, when the temperature of the engine cooling water is low or the charge amount of the battery is small, the engine speed is increased to promote the warm-up of the engine and the charging of the battery, or when the engine speed is low. In order to prevent the muffled sound, it is necessary to shift the resonance point by changing the rotation speed of the engine. That is, the negative driving force command value y1 and the negative driving torque command value T determined by the vehicle speed control are satisfied while satisfying the engine rotation speed restriction depending on the vehicle state.
realize or

FIG. 10 shows an engine characteristic diagram (engine torque line and equal output line) when the engine output and the engine torque are negative. In the figure, a state 1 represents an engine torque line in a state where the throttle valve is fully closed and a fuel cut is prohibited. State 2 represents the engine torque line when the throttle valve is fully closed and the fuel is cut off. Further, state 3 represents the engine torque line when the throttle valve is open and the fuel is cut off. State 3
Then, the engine torque line changes according to the throttle valve opening. Nerlmt indicates an example of the engine speed restricted by the state of the vehicle.

If there is no restriction on the engine rotation speed due to the state of the vehicle, state 1 (throttle valve fully closed and fuel cut prohibited state) or state 2 (throttle valve fully closed and fuel cut state) shown in FIG. From the intersection of the engine torque line and the equal output line, the operating point of the engine that achieves the output command value L is determined. Actually, the target engine operating point corresponding to the output value (negative value), that is, the engine rotation speed command value determined by the intersection of the equal output line and the engine torque line in state 1 or state 2 is stored in advance as map data. In advance, the engine rotational speed command value Ner corresponding to the output command value L (negative value) is calculated in a table.

On the other hand, when there is a restriction on the engine rotational speed due to the state of the vehicle, states 1, 2 and 3 (throttle valve open and fuel cut state) shown in FIG.
The engine operating point that achieves the output command value L (negative value) is determined from the intersection of the engine torque line and the equal output line. Actually, taking into account the target engine operating point corresponding to the output value (negative value), that is, the engine rotation speed Nerlmt restricted by the state of the vehicle, the equal output line and the state 1 or state 2 or state 3 are considered. The engine rotation speed command value determined by the intersection with the engine torque line is stored in advance as map data, and the engine rotation speed command value Ner corresponding to the output command value L (negative value) is tabulated and calculated.

The engine rotational speed command value Ner in the case of the negative driving force command value or the driving torque command value shown in FIG.
Will be described later.

In step 12, an engine speed limit determined by the speed ratio range, the engine, and the like that can be taken by the continuously variable transmission 10 is applied to the engine speed command value Ner. In the following step 13, a gear ratio command value Gcvt and an engine torque command value Ter are determined. Assuming that the final reduction ratio is Gf and the effective radius of the tire is Rt,

Gcvt = Ner.Rt / Vsp / Gf, Ter = Tor / Gcvt / Gf At step 14, the engine torque controller 13
The engine torque command value Ter, the fuel cut prohibition or permission flag, and the throttle valve opening command value TVOr
Is transmitted to the transmission controller 14 and the gear ratio command value G
Send cvt and end the process.

Next, a method of calculating the engine speed command value Ner when the driving force command value y1 or the driving torque command value Tor is negative will be described with reference to FIG. In step 31, it is confirmed whether or not there is a restriction on the engine rotation speed due to the state of the vehicle. That is, when the engine cooling water temperature detected by the water temperature sensor 15 is lower than the reference temperature, the SOC
When the SOC of the battery detected by the sensor 16 is lower than the reference SOC, or when the vehicle speed detected by the vehicle speed sensor 7 is lower than the speed at which the muffled sound is generated, the engine speed is restricted depending on the state of the vehicle. It is determined whether or not it is necessary. If it is necessary to restrict the engine rotation speed, the process proceeds to step 32; otherwise, the process proceeds to step 33.

If it is necessary to restrict the engine rotation speed, at step 32, the throttle valve opening command value TV
Initialize Or and proceed to step 34. In step 34, it is determined whether or not the current throttle valve opening command value TVOr is equal to or less than the upper limit value TVOlmt of the throttle valve opening in the state 3 (throttle valve is open and the fuel is cut off). Current throttle valve opening command value T
If VOr is equal to or smaller than the upper limit value TVOlmt, the process proceeds to step 35; otherwise, the process proceeds to step 39.

The current throttle valve opening command value TVO
If r is equal to or smaller than the upper limit value TVOlmt, a fuel cut flag is set in step 35 to perform a fuel cut. In the following step 36, the operating point of the engine is determined from the intersection of the engine torque line and the equal output line in state 2 (throttle valve fully closed and fuel cut state) and state 3 (throttle valve open and fuel cut state). An engine speed command value Ner corresponding to the output command value L is determined by a lookup operation using the map data for this purpose. In this lookup calculation 1, an output engine rotation speed command value Ner is obtained from two inputs of a throttle valve opening command value TVOr and an output command value L.

In step 37, it is confirmed whether or not the previously determined engine speed command value Ner satisfies the restriction of the engine speed from the state of the vehicle. For example, the engine rotation speed is set to Nerlmt depending on the vehicle cooling water temperature, the state of charge of the battery, and the muffled sound.
If the engine rotation speed command value Ner is higher than the engine rotation speed Nerlmt restricted from the state of the vehicle, the constraint is satisfied, as shown in FIG. In this case, it is assumed that the constraint is not satisfied. If the restriction on the engine rotation speed due to the state of the vehicle is satisfied, the program returns to the program shown in FIG. In step 38, a predetermined value ΔTVO is added to the current throttle valve opening command value TVOr, the process returns to step 34, and the above processing is repeated.

The current throttle valve opening command value TVO
When r exceeds the upper limit TVOlmt in state 3,
In step 39, the fuel cut flag is reset to prohibit the fuel cut. In the following step 40, state 1
An engine speed command value corresponding to the output command value L using map data for determining the engine operating point from the intersection of the engine torque line and the equal output line when the throttle valve is fully closed and the fuel cut is prohibited. Ner is determined by a lookup operation. In this lookup operation 2, the output command value L
An output engine speed command value Ner is obtained from only one input.

On the other hand, if there is no restriction on the engine rotation speed due to the state of the vehicle, the routine proceeds to step 41 after initializing the throttle valve opening command value TVOr in step 33. In step 41, the output L1 (see FIG. 10) that satisfies the lower limit Nemin of the engine rotational speed is compared with the output command value L in state 2 (the throttle valve is fully closed and the fuel is cut off). When the output command value L is equal to or less than L1, the process proceeds to step 42, and otherwise, the process proceeds to step 44.

If the output command value L is equal to or less than the output L1 satisfying the lower limit value Nemin of the engine speed in the state 2, a fuel cut flag is set in step 42 to perform a fuel cut, and the routine proceeds to step 43. In step 43,
State 2 (throttle valve fully closed and fuel cut off)
Using the map data for determining the engine operating point from the intersection of the engine torque line and the equal output line, the engine rotation speed command value Ner corresponding to the output command value L is determined by look-up calculation. In this lookup operation 3, the engine speed command value Ner of the output from one input of only the output command value L is output.
Ask for. Thereafter, the process returns to the program shown in FIG.

On the other hand, when the output command value L is larger than the output L1 which satisfies the lower limit value Nemin of the engine rotation speed in the state 2, the fuel cut flag is reset at step 44 to inhibit the fuel cut, and the routine proceeds to step 45. move on.
In step 45, the output command value L is corresponded using the map data for determining the engine operating point from the intersection of the engine torque line and the equal output line in state 1 (throttle valve is fully closed and fuel cut is prohibited). The engine rotation speed command value Ner to be executed is determined by a lookup operation. In this lookup operation 4, an output engine speed command value Ner is obtained from one input of only the output command value L. Thereafter, the process returns to the program shown in FIG.

The method for determining the operating point of the engine will be briefly described with reference to FIGS. As described above, according to the known linear control theory, the actual vehicle speed Vsp is changed to the vehicle speed command value Vspr.
The driving force command value y1 and the driving torque command value Tor are calculated so as to be equal to. Then, an engine torque command value Ter and a gear ratio command value Gcvt of the continuously variable transmission are calculated based on the drive torque command value Tor.

When the driving force command value y1 or the driving torque command value Tor is positive, the engine speed command value Ne is determined from the intersection of the equal output line of the output command value L and the engine optimum fuel economy operation line. As shown in FIG. 9, the engine can be operated along the optimal fuel efficiency driving line. Further, when the gear ratio cannot be further increased, the engine speed is limited by the engine speed at that time, so that the engine cannot be operated along the optimal fuel efficiency driving line, and only the driving torque command value Tor is achieved. .

When the driving force command value y1 or the driving torque command value Tor is negative, an equal output line of the output command value L and the state 1
The operating point of the engine is determined from the intersection with the engine torque lines of ~ 3, and the negative driving force command value y1 and the negative driving torque command value Tor are achieved.

First, when there is no restriction on the engine rotation speed from the state of the vehicle, and the output command value L
If the output L1 is equal to or less than the output L1 that satisfies the lower limit Nemin of the engine rotation speed when the throttle valve is fully closed and the fuel is cut off, as shown in step 43 of FIG. 5 and FIG. And an engine torque command value Ner is determined from the intersection of
Negative driving force command value y1 and negative driving torque command value Tor
To achieve.

If there is no restriction on the engine speed from the state of the vehicle and the output command value L is larger than the output L1 which satisfies the engine speed lower limit Nemin of the state 2, As shown in FIG. 10 and 45, the engine speed command value Ner is determined from the intersection of the equal output line of the output command value L and the engine torque line in state 1 (throttle valve fully closed and fuel cut is prohibited). A negative driving force command value y1 and a negative driving torque command value Tor are realized.

As described above, when the driving force command value y1 or the driving torque command value Tor is negative and there is no restriction on the engine speed from the state of the vehicle, as shown in FIG. By using the engine torque characteristics of 1 (throttle valve fully closed and fuel cut prohibited state) and state 2 (throttle valve fully closed and fuel cut state), negative drive torque command value Tor and negative drive force command value y1 can be realized continuously. This state 1
The method of determining the operating point of the engine using the engine torque characteristics of the state 2 and the state 2 is also effective as a method of preventing vehicle speed hunting during vehicle speed control due to a discontinuous point of negative engine torque (fuel cut / recovery). It is.

On the other hand, when there is a restriction on the engine speed from the state of the vehicle, as shown in steps 36 and 40 of FIG. 5 and FIG.
The engine rotational speed command value Ner is determined from the intersection with the engine torque lines of (1) to (3) to realize the negative driving force command value y1 and the driving torque command value Tor.

However, the throttle valve opening upper limit value TV in state 3 (throttle valve is open and fuel is cut off)
If the engine torque line in the case of Olmt cannot satisfy the restriction of the engine rotation speed from the state of the vehicle, the engine torque line in state 1 (throttle valve is fully closed and fuel cut is prohibited) is used. An engine speed command value Ner is determined, and a negative driving force command value y1 and a negative driving torque command value Tor are realized.

An example of a method for determining the operating point of the engine when there is a restriction on the engine rotation speed from the state of the vehicle will be described. Now, as shown in FIG. 10, at the intersection A between the engine torque line in state 2 (the throttle valve is fully closed and the fuel cut state) and the equal output line of the output command value L, the driving force command value y1 and the driving torque command value When implementing Tor,
From the state of the vehicle, the engine speed is restricted (Ner ≧ Nerlm
t), if it is desired to increase the engine rotation speed command value Ner while maintaining the output command value L, the output command value L is equal to the output line and the engine in state 3 (throttle valve is open and fuel is cut). By changing the operating point of the engine to the intersection B with the torque line, the constraint (Ner ≧ Nerlmt)
, The negative driving force command value y1 and the negative driving torque command value Tor can be realized. Since the negative engine torque is determined by the friction and the pumping loss of the engine, the pumping loss is changed by adjusting the throttle valve opening in the fuel cut state to continuously adjust the negative engine torque.

Further, during operation at the point B, the output command value L becomes L
When it decreases to 2, the operating point of the engine is changed to a point C that satisfies the constraint (Ner ≧ Nerlmt) and the output command value L2 simultaneously. That is, the equal output line of the output command value L2 and the state 3
The operating point is changed to the intersection C with the engine torque line when the throttle valve is open and the fuel is cut off.

FIG. 12 shows the engine output P and the throttle valve opening TV in the above-described example of determining the engine operating point.
6 is a time chart showing changes in O, engine rotation speed Ne, and fuel cut flag. When the operating point of the engine is changed from the point A to the point B due to a restriction from the state of the vehicle, the throttle valve opening command value TVOr is increased (opened).
, The actual throttle valve opening TVO changes from the fully closed state to the open state, and the negative engine torque decreases.
At the same time, the actual engine speed Ne increases in accordance with the increase in the engine speed command value Ne. As a result, the actual engine output P maintains a value corresponding to the output command value L. Further, when the operating point of the engine is changed from the point B to the point C, while maintaining the current engine rotation speed Ne,
As the throttle valve opening command value TVOr decreases, the actual throttle valve opening TVO also decreases, and the negative engine torque increases. As a result, the actual engine output P
Decreases to a value corresponding to the output command value L2 (negative engine output increases).

As described above, the negative engine torque between the state 1 (the throttle valve is fully closed and the fuel cut is prohibited) and the state 2 (the throttle valve is fully closed and the fuel cut state) is changed to the state 3 ( (The throttle valve is open and the fuel is cut off), and the engine speed is constrained by the state of the vehicle when the driving force command value y1 or the driving torque command value Tor is negative. Since any one of the states 1 to 3 is set, the negative driving force command is satisfied while satisfying the engine rotation speed constraints from the vehicle state such as engine warm-up, battery charging, and muffled sound. The value y1 and the negative drive torque command value Tor can be achieved.

In the above-described embodiment, an example is shown in which the present invention is applied to a vehicle equipped with a continuously variable transmission for controlling the vehicle speed. However, the present invention is not limited to a vehicle for controlling the vehicle speed. A vehicle equipped with a continuously variable transmission that determines a driving force command value or a driving torque command value by various controls such as distance control, or a driving force command value or a driving torque command value is determined according to the amount of depression of an accelerator pedal by a passenger. The present invention can also be applied to a vehicle or a vehicle in which a driving force command value or a driving torque command value is determined by an accelerator pedal depression amount of a passenger and various controls.

In the case where the driving force command value y1 is determined based on the accelerator pedal depression amount acc of the occupant regardless of the vehicle speed control or the following distance control, the vehicle speed using the accelerator pedal depression amount as shown in FIG. , A driving force corresponding to the accelerator pedal depression amount acc and the vehicle speed Vsp is obtained from the map data by a look-up calculation, and the driving force is set as a driving force command value y1. Then, a drive torque command value Tor is calculated from the drive force command value y1. In a vehicle having a plurality of driving modes such as a sports driving mode, optimal map data is set for each driving mode, and the map data is selected according to the driving mode, and a driving force command value is tabulated. do it.

Further, in the above-described embodiment, examples of the vehicle state in which the engine rotational speed is required to be restricted include a case where the engine cooling water temperature is low, a case where the charge amount of the battery is low, and a low vehicle speed at which a muffled sound is generated. I explained it up,
The state of the vehicle is not limited to the above embodiment. For example, when a vehicle air conditioner is operated, the engine speed is increased to cover an air conditioning load for driving a compressor and the like and an electric load for driving a blower fan and the like. The operation stop state of the device is also a state of the vehicle that restricts the engine rotation speed. When the lamps are turned on, the engine speed is increased,
Electric loads for lighting the lamps are covered, and turning on and off the lamps is also a state of the vehicle that limits the engine rotation speed.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing switching between an ideal air-fuel ratio (stoichiometric) state and a lean-burn air-fuel ratio state.

FIG. 3 is a diagram showing switching between a low rotation cam and a high rotation cam.

FIG. 4 is a flowchart showing a vehicle speed control program.

FIG. 5 is a flowchart illustrating an engine rotation speed command value calculation routine when a driving force command value or a driving torque command value is negative.

FIG. 6 is a control block diagram illustrating vehicle speed feedback control.

FIG. 7 is a diagram showing characteristics of a throttle valve opening degree with respect to an engine torque with an engine rotation speed as a parameter.

FIG. 8 is a diagram illustrating a configuration of a model matching compensator.

FIG. 9 is a diagram showing a characteristic diagram of the engine (an equal output line, an equal fuel consumption line, and an optimum fuel economy driving line) when the engine output and the engine torque are positive.

FIG. 10 is a diagram showing a characteristic diagram (engine torque line and equal output line) of the engine when the engine output and the engine torque are negative.

FIG. 11 is a diagram showing a characteristic diagram (engine torque line and equal output line) of the engine when the engine output and the engine torque are negative.

FIG. 12 is a time chart showing changes in an engine output P, a throttle valve opening TVO, an engine rotation speed Ne, and a fuel cut flag in an example of determining an engine operating point.

FIG. 13 is a diagram showing a map of a driving force with respect to a vehicle speed using an accelerator pedal depression amount as a parameter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Set switch 2 Accelerate switch 3 Coast switch 4 Cancel switch 5 Brake switch 6 Crank angle sensor 7 Vehicle speed sensor 8 Accelerator sensor 9 Lean combustion type engine 9a Throttle valve actuator 9b Injector 9c Spark plug 10 Belt type continuously variable transmission 11 Torque converter 12 Vehicle speed controller 13 Engine torque controller 14 Gear ratio controller 15 Engine cooling water temperature sensor 16 SOC sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 9/02 F02D 9/02 N 3G301 R 3J067 315 315B 11/10 11/10 11/10 U 41/12 330 41 / 12 330J 43/00 301 43/00 301H 301K F16H 9/00 F16H 9/00 F 63/06 63/06 // F16H 59:18 59:74 (72) Inventor Hiroyuki Ashizawa 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Address F-term in Nissan Motor Co., Ltd. (reference) 3D041 AA18 AA26 AA41 AA69 AB01 AC01 AC20 AD02 AD04 AD10 AD14 AD51 AE04 AE08 AE36 AF00 AF01 3D044 AA01 AA19 AA25 AB01 AC03 AC05 AC07 AC15 AC26 AC41 AC59 AD04 AE04AE07AE04 AA00 CA14 CA19 CA20 DA04 FA00 FA03 FA06 FA07 FA11 GA09 GA10 GA11 GA33 GA37 GA41 GA46 GA50 3G084 AA00 AA04 BA05 BA13 BA32 DA04 DA05 DA39 EA11 EB00 EB08 EB11 FA00 FA05 FA10 FA20 FA33 FA38 3G093 AA06 AB00 BA14 BA15 BA23 BA32. NE17 NE19 PA11Z PE01Z PE03Z PE08Z PF03Z PF11Z PF13Z 3J067 AC23 AC34 BB04 CA02 CA07 CA09 CA21 CA22 CA40

Claims (6)

[Claims] 1. A command value determining means for determining a driving force command value or a driving torque command value of a vehicle, and calculating an engine torque command value and a gear ratio command value for achieving the driving force command value or the driving torque command value. Command value calculating means, an engine control means for controlling the engine such that the engine torque matches the engine torque command value, and a continuously variable transmission for controlling the continuously variable transmission such that the speed ratio matches the speed ratio command value. A driving force control device for a vehicle equipped with a continuously variable transmission having a motor control means, wherein the driving force command value or the driving torque command value is negative, and the engine rotation speed restricted from the vehicle state is controlled. In consideration of,
The state of the engine is a throttle valve fully closed and fuel cut prohibited state (hereinafter referred to as state 1), a throttle valve fully closed and fuel cut state (hereinafter referred to as state 2),
Driving force control for a vehicle equipped with a continuously variable transmission, comprising: an engine state setting means for setting the throttle valve to open and to a fuel cut state (hereinafter referred to as state 3). apparatus. 2. A driving force control apparatus for a vehicle equipped with a continuously variable transmission according to claim 1, wherein the state of the vehicle includes a temperature of engine cooling water, a state of charge of a battery, an operation of an air conditioner, and lamps. A driving force control device for a vehicle equipped with a continuously variable transmission, which includes lighting of the vehicle and vehicle speed. 3. A driving force control device for a vehicle equipped with a continuously variable transmission according to claim 1 or 2, wherein the command value calculating means is configured to output a driving force command value or a driving force in the setting state of the engine. A driving force control device for a vehicle equipped with a continuously variable transmission, wherein an operating point of an engine is determined based on a torque command value, and a gear ratio command value is calculated based on the engine operating point. 4. A driving force control apparatus for a vehicle equipped with a continuously variable transmission according to claim 1, wherein said command value determining means is adapted to match a vehicle speed with a vehicle speed command value. A driving force control device for a vehicle equipped with a continuously variable transmission, which determines a driving force command value or a driving torque command value. 5. A driving force control device for a vehicle equipped with a continuously variable transmission according to claim 1, wherein said command value determining means drives based on an accelerator pedal depression amount of an occupant. A driving force control device for a vehicle equipped with a continuously variable transmission, which determines a force command value or a driving torque command value. 6. A driving force control device for a vehicle equipped with a continuously variable transmission according to claim 1, wherein said command value determining means determines a distance between the vehicle and a preceding vehicle by a vehicle distance command. A driving force control device for a vehicle equipped with a continuously variable transmission, wherein a driving force command value or a driving torque command value for matching the driving force command value is determined.